Structural basis for drug-induced allosteric changes to human β-cardiac myosin motor activity

PubMed Central

Winkelmann, Donald A.; Forgacs, Eva; Miller, Matthew T.; Stock, Ann M.

2015-01-01

Omecamtiv Mecarbil (OM) is a small molecule allosteric effector of cardiac myosin that is in clinical trials for treatment of systolic heart failure. A detailed kinetic analysis of cardiac myosin has shown that the drug accelerates phosphate release by shifting the equilibrium of the hydrolysis step towards products, leading to a faster transition from weak to strong actin-bound states. The structure of the human β-cardiac motor domain (cMD) with OM bound reveals a single OM-binding site nestled in a narrow cleft separating two domains of the human cMD where it interacts with the key residues that couple lever arm movement to the nucleotide state. In addition, OM induces allosteric changes in three strands of the β-sheet that provides the communication link between the actin-binding interface and the nucleotide pocket. The OM-binding interactions and allosteric changes form the structural basis for the kinetic and mechanical tuning of cardiac myosin. PMID:26246073

COUP-TF1 antagonizes Nkx2.5-mediated activation of the calreticulin gene during cardiac development.

PubMed

Guo, L; Lynch, J; Nakamura, K; Fliegel, L; Kasahara, H; Izumo, S; Komuro, I; Agellon, L B; Michalak, M

2001-01-26

Calreticulin, a Ca(2+) binding chaperone of the endoplasmic reticulum, is also highly expressed in the embryonic heart, and knockout of the calreticulin gene is lethal during embryogenesis because of impaired cardiac development. The protein is down-regulated after birth, and elevated expression of calreticulin in newborn hearts is associated with severe cardiac pathology and death. Here we show that the transcription factor Nkx2.5 activates expression of the calreticulin gene in the heart. Binding of chicken ovalbumin upstream promoter-transcription factor 1 to the Nkx2.5 binding site suppresses transcription from the calreticulin promoter. Nkx2.5 and chicken ovalbumin upstream promoter-transcription factor 1 play antagonistic roles in regulating the expression of calreticulin during cardiac development. These studies indicate that cardiac-specific transcription factor Nkx2.5 plays a central role in activating calreticulin expression and that there is a cooperation between chicken ovalbumin upstream promoter-transcription factor 1 and Nkx2.5 at the calreticulin promoter.

[High non-specific binding of the beta(1) -selective radioligand 2-(125)I-ICI-H].

PubMed

Riemann, B; Law, M P; Kopka, K; Wagner, St; Luthra, S; Pike, V W; Neumann, J; Kirchhefer, U; Schmitz, W; Schober, O; Schäfers, M

2003-08-01

As results of cardiac biopsies suggest, myocardial beta(1) -adrenoceptor density is reduced in patients with chronic heart failure. However, changes in cardiac beta(2)-adrenoceptors vary. With suitable radiopharmaceuticals single photon emission computed tomography (SPECT) and positron emission tomography (PET) offer the opportunity to assess beta-adrenoceptors non-invasively. Among the novel racemic analogues of the established beta(1)-selective adrenoceptor antagonist ICI 89.406 the iodinated 2-I-ICI-H showed high affinity and selectivity to beta(1)-adrenoceptors in murine ventricular membranes. The aim of this study was its evaluation as a putative sub-type selective beta(1)-adrenergic radioligand in cardiac imaging. Competition studies in vitro and in vivo were used to investigate the kinetics of 2-I-ICI-H binding to cardiac beta-adrenoceptors in mice and rats. In addition, the radiosynthesis of 2-(125)I-ICI-H from the silylated precursor 2-SiMe(3)-ICI-H was established. The specific activity was 80 GBq/ micro mol, the radiochemical yield ranged from 70 to 80%. The unlabelled compound 2-I-ICI-H showed high beta(1)-selectivity and -affinity in the in vitro competition studies. In vivo biodistribution studies apparently showed low affinity to cardiac beta-adrenoceptors. The radiolabelled counterpart 2-(125)I-ICI-H showed a high degree of non-specific binding in vitro and no specific binding to cardiac beta(1)-adrenoceptors in vivo. Because of its high non-specific binding 2-(125)I-ICI-H is no suitable radiotracer for imaging in vivo.

AFFINE-CORRECTED PARADISE: FREE-BREATHING PATIENT-ADAPTIVE CARDIAC MRI WITH SENSITIVITY ENCODING

PubMed Central

Sharif, Behzad; Bresler, Yoram

2013-01-01

We propose a real-time cardiac imaging method with parallel MRI that allows for free breathing during imaging and does not require cardiac or respiratory gating. The method is based on the recently proposed PARADISE (Patient-Adaptive Reconstruction and Acquisition Dynamic Imaging with Sensitivity Encoding) scheme. The new acquisition method adapts the PARADISE k-t space sampling pattern according to an affine model of the respiratory motion. The reconstruction scheme involves multi-channel time-sequential imaging with time-varying channels. All model parameters are adapted to the imaged patient as part of the experiment and drive both data acquisition and cine reconstruction. Simulated cardiac MRI experiments using the realistic NCAT phantom show high quality cine reconstructions and robustness to modeling inaccuracies. PMID:24390159

Biomechanics of Early Cardiac Development

PubMed Central

Goenezen, Sevan; Rennie, Monique Y.

2012-01-01

Biomechanics affect early cardiac development, from looping to the development of chambers and valves. Hemodynamic forces are essential for proper cardiac development, and their disruption leads to congenital heart defects. A wealth of information already exists on early cardiac adaptations to hemodynamic loading, and new technologies, including high resolution imaging modalities and computational modeling, are enabling a more thorough understanding of relationships between hemodynamics and cardiac development. Imaging and modeling approaches, used in combination with biological data on cell behavior and adaptation, are paving the road for new discoveries on links between biomechanics and biology and their effect on cardiac development and fetal programming. PMID:22760547

Kruppel-like factor 15 is required for the cardiac adaptive response to fasting.

PubMed

Sugi, Keiki; Hsieh, Paishiun N; Ilkayeva, Olga; Shelkay, Shamanthika; Moroney, Bridget; Baadh, Palvir; Haynes, Browning; Pophal, Megan; Fan, Liyan; Newgard, Christopher B; Prosdocimo, Domenick A; Jain, Mukesh K

2018-01-01

Cardiac metabolism is highly adaptive in response to changes in substrate availability, as occur during fasting. This metabolic flexibility is essential to the maintenance of contractile function and is under the control of a group of select transcriptional regulators, notably the nuclear receptor family of factors member PPARα. However, the diversity of physiologic and pathologic states through which the heart must sustain function suggests the possible existence of additional transcriptional regulators that play a role in matching cardiac metabolism to energetic demand. Here we show that cardiac KLF15 is required for the normal cardiac response to fasting. Specifically, we find that cardiac function is impaired upon fasting in systemic and cardiac specific Klf15-null mice. Further, cardiac specific Klf15-null mice display a fasting-dependent accumulation of long chain acylcarnitine species along with a decrease in expression of the carnitine translocase Slc25a20. Treatment with a diet high in short chain fatty acids relieves the KLF15-dependent long chain acylcarnitine accumulation and impaired cardiac function in response to fasting. Our observations establish KLF15 as a critical mediator of the cardiac adaptive response to fasting through its regulation of myocardial lipid utilization.

Intermittent cardiac overload results in adaptive hypertrophy and provides protection against left ventricular acute pressure overload insult.

PubMed

Moreira-Gonçalves, Daniel; Henriques-Coelho, Tiago; Fonseca, Hélder; Ferreira, Rita; Padrão, Ana Isabel; Santa, Cátia; Vieira, Sara; Silva, Ana Filipa; Amado, Francisco; Leite-Moreira, Adelino; Duarte, José Alberto

2015-09-01

The present study aimed to test whether a chronic intermittent workload could induce an adaptive cardiac phenotype Chronic intermittent workload induced features of adaptive hypertrophy This was paralleled by protection against acute pressure overload insult The heart may adapt favourably to balanced demands, regardless of the nature of the stimuli. The present study aimed to test whether submitting the healthy heart to intermittent and tolerable amounts of workload, independently of its nature, could result in an adaptive cardiac phenotype. Male Wistar rats were subjected to treadmill running (Ex) (n = 20), intermittent cardiac overload with dobutamine (ITO) (2 mg kg(-1) , s.c.; n = 20) or placebo administration (Cont) (n = 20) for 5 days week(-1) for 8 weeks. Animals were then killed for histological and biochemical analysis or subjected to left ventricular haemodynamic evaluation under baseline conditions, in response to isovolumetric contractions and to sustained LV acute pressure overload (35% increase in peak systolic pressure maintained for 2 h). Baseline cardiac function was enhanced only in Ex, whereas the response to isovolumetric heartbeats was improved in both ITO and Ex. By contrast to the Cont group, in which rats developed diastolic dysfunction with sustained acute pressure overload, ITO and Ex showed increased tolerance to this stress test. Both ITO and Ex developed cardiomyocyte hypertrophy without fibrosis, no overexpression of osteopontin-1 or β-myosin heavy chain, and increased expression of sarcoplasmic reticulum Ca(2+) protein. Regarding hypertrophic pathways, ITO and Ex showed activation of the protein kinase B/mammalian target of rapamycin pathway but not calcineurin. Mitochondrial complex IV and V activities were also increased in ITO and Ex. Chronic submission to controlled intermittent cardiac overload, independently of its nature, results in an adaptive cardiac phenotype. Features of the cardiac overload, such as the duration and magnitude of the stimuli, may play a role in the development of an adaptive or maladaptive phenotype. © 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.

Denervation does not alter the number of neuronal bungarotoxin binding sites on autonomic neurons in the frog cardiac ganglion.

PubMed

Sargent, P B; Bryan, G K; Streichert, L C; Garrett, E N

1991-11-01

The binding of neuronal bungarotoxin (n-BuTX; also known as bungarotoxin 3.1, kappa-bungarotoxin, and toxin F) was analyzed in normal and denervated parasympathetic cardiac ganglia of the frog Rana pipiens, n-BuTX blocks both EPSPs and ACh potentials at 5-20 nM, as determined by intracellular recording techniques. Scatchard analysis on homogenates indicates that cardiac ganglia have two classes of binding sites for 125I-n-BuTX: a high-affinity site with an apparent dissociation constant (Kd,app) of 1.7 nM and a Bmax (number of binding sites) of 3.8 fmol/ganglion and a low-affinity site with a Kd,app of 12 microM and a Bmax of 14 pmol/ganglion. alpha-Bungarotoxin does not appear to interfere with the binding of 125I-n-BuTX to either site. The high-affinity binding site is likely to be the functional nicotinic ACh receptor (AChR), given the similarity between its affinity for 125I-n-BuTX and the concentration of n-BuTX required to block AChR function. Light microscopic autoradiographic analysis of 125I-n-BuTX binding to the ganglion cell surface reveals that toxin binding is concentrated at synaptic sites, which were identified using a synaptic vesicle-specific antibody. Scatchard analysis of autoradiographic data reveals that 125I-n-BuTX binding to the neuronal surface is saturable and has a Kd,app similar to that of the high-affinity binding site characterized in homogenates. Surface binding of 125I-n-BuTX is blocked by nicotine, carbachol, and d-tubocurarine (IC50 less than 20 microM), but not by atropine (IC50 greater than 10 mM). Denervation of the heart increases the ACh sensitivity of cardiac ganglion cells but has no effect upon the number of high-affinity binding sites for 125I-n-BuTX in tissue homogenates. Moreover, autoradiographic analysis indicates that denervation does not alter the number of 125I-n-BuTX binding sites on the ganglion cell surface. n-BuTX is as effective in reducing ganglion cell responses to ACh in denervated ganglia as it is in normally innervated ganglia. These results suggest that denervation alters neither the total number of nicotinic AChRs in the cardiac ganglion nor the number found on the surface of ganglion cells. These autonomic neurons thus respond differently to denervation than do skeletal myofibers. The increase in ACh sensitivity displayed by cardiac ganglion cells upon denervation cannot be explained by changes in AChR number.

Candida glabrata binds to glycosylated and lectinic receptors on the coronary endothelial luminal membrane and inhibits flow sense and cardiac responses to agonists.

PubMed

Torres-Tirado, David; Knabb, Maureen; Castaño, Irene; Patrón-Soberano, Araceli; De Las Peñas, Alejandro; Rubio, Rafael

2016-01-01

Candida glabrata (CG) is an opportunistic fungal pathogen that initiates infection by binding to host cells via specific lectin-like adhesin proteins. We have previously shown the importance of lectin-oligosaccharide binding in cardiac responses to flow and agonists. Because of the lectinic-oligosaccharide nature of CG binding, we tested the ability of CG to alter the agonist- and flow-induced changes in cardiac function in isolated perfused guinea pig hearts. Both transmission and scanning electron microscopy showed strong attachment of CG to the coronary endothelium, even after extensive washing. CG shifted the coronary flow vs. auricular-ventricular (AV) delay relationship upward, indicating that greater flow was required to achieve the same AV delay. This effect was completely reversed with mannose, partially reversed with galactose and N-acetylgalactosamine, but hyaluronan had no effect. Western blot analysis was used to determine binding of CG to isolated coronary endothelial luminal membrane (CELM) receptors, and the results indicate that flow-sensitive CELM receptors, ANG II type I, α-adrenergic 1A receptor, endothelin-2, and VCAM-1 bind to CG. In addition, CG inhibited agonist-induced effects of bradykinin, angiotensin, and phenylephrine on AV delay, coronary perfusion pressure, and left ventricular pressure. Mannose reversed the inhibitory effects of CG on the agonist responses. These results suggest that CG directly binds to flow-sensitive CELM receptors via lectinic-oligosaccharide interactions with mannose and disrupts the lectin-oligosaccharide binding necessary for flow-induced cardiac responses. Copyright © 2016 the American Physiological Society.

[Analogies between heart and respiratory muscle failure. Importance to clinical practice].

PubMed

Köhler, D

2009-01-01

Heart failure is an established diagnosis. Respiratory muscle or ventilatory pump failure, however, is less well known. The latter becomes obvious through hypercapnia, caused by hypoventilation. The respiratory centre tunes into hypercapnea in order to prevent the danger of respiratory muscle overload (hypercapnic ventilatory failure). Hypoventilation will consecutively cause hypoxemia but this will not be responsible for performance limitation. One therefore has to distinguish primary hypoxemia evolving from diseases in the lung parenchyma. Here hypoxemia is the key feature and compensatory hyperventilation usually decreases PaCO2 levels. The cardiac as well as the respiratory pump adapt to an inevitable burden caused by chronic disease. In either case organ muscle mass will increase. If the burden exceeds the range of possible physiological adaptation, compensatory mechanisms will set in that are similar in both instances. During periods of overload either muscle system is mainly fueled by muscular glycogen. In the recovery phase (e. g. during sleep) stores are replenished, which can be recognized by down-regulation of the blood pressure in case of the cardiac pumb or by augmentation of hypercapnia through hypoventilation in case of the respiratory pump. The main function of cardiac and respiratory pump is maintenance of oxygen transport. The human body has developed certain compensatory mechanisms to adapt to insufficient oxygen supply especially during periods of overload. These mechanisms include shift of the oxygen binding curve, expression of respiratory chain isoenzymes capable of producing ATP at lower partial pressures of oxygen and the development of polyglobulia. Medically or pharmacologically the cardiac pump can be unloaded with beta blockers, the respiratory pump by application of inspired oxygen. Newer forms of therapy augment the process of recovery. The heart can be supported through bypass surgery or intravascular pump systems, while respiratory muscles may be supported through elective ventilatory support (mainly non-invasive) in the patient's home. The latter treatment in particular will increase patient endurance and quality of life and decrease mortality. Heart and respiratory pump failure share many common features. Since both take care of oxygen supply to the body, their function and compensatory mechanisms are closely related and linked.

Cardiovascular adaptations to marathon running : the marathoner's heart.

PubMed

Thompson, Paul D

2007-01-01

Endurance exercise training produces a series of cardiac adaptations including resting bradycardia, first and second degree atrioventricular block, increased intolerance to orthostatic stress, and enlargement of the left ventricular walls and of all cardiac chambers. Cardiac dimensions may be increased beyond the upper limits of normal and some endurance athletes demonstrate mild reductions in estimated left ventricular ejection fraction. Among athletes, such adaptations occur primarily in well trained endurance athletes. Clinicians should be aware of the cardiac changes accompanying endurance training to avoid unnecessary evaluation of physiological changes. On the other hand, the presence of conduction abnormalities or cardiac enlargement in low level or recreational athletes should prompt a search for pathological causes. Many of these findings were presented in the 1977 report on the marathon and have simply been better defined with subsequent studies.

The Popeye Domain Containing Genes and Their Function as cAMP Effector Proteins in Striated Muscle.

PubMed

Brand, Thomas

2018-03-13

The Popeye domain containing (POPDC) genes encode transmembrane proteins, which are abundantly expressed in striated muscle cells. Hallmarks of the POPDC proteins are the presence of three transmembrane domains and the Popeye domain, which makes up a large part of the cytoplasmic portion of the protein and functions as a cAMP-binding domain. Interestingly, despite the prediction of structural similarity between the Popeye domain and other cAMP binding domains, at the protein sequence level they strongly differ from each other suggesting an independent evolutionary origin of POPDC proteins. Loss-of-function experiments in zebrafish and mouse established an important role of POPDC proteins for cardiac conduction and heart rate adaptation after stress. Loss-of function mutations in patients have been associated with limb-girdle muscular dystrophy and AV-block. These data suggest an important role of these proteins in the maintenance of structure and function of striated muscle cells.

Exploration of the psychological impact and adaptation to cardiac events in South Asians in the UK: a qualitative study

PubMed Central

Bhattacharyya, Mimi; Stevenson, Fiona; Walters, Kate

2016-01-01

Objective There is little research on how different ethnic groups adapt after an acute cardiac event. This qualitative study explores between-ethnicity and within-ethnicity variation in adaptation, and the psychological impact of an acute cardiac event among UK South Asian and white British people. Setting We purposively sampled people by ethnic group from general practices in London who had a new myocardial infarction, angina or acute arrhythmia in the preceding 18 months. Participants We conducted 28 semistructured interviews for exploring the psychological symptoms, experiences and adaptations following a cardiac event among South Asians (Indian and Bangladeshi) in comparison to white British people. Data were analysed using a thematic ‘framework’ approach. Results Findings showed heterogeneity in experiences of the cardiac event and its subsequent psychological and physical impact. Adaptation to the event related predominantly to life circumstances, personal attitudes and employment status. Anxiety and low mood symptoms were common sequelae, especially in the Bangladeshi group. Indian men tended to normalise symptoms and the cardiac event, and reported less negative mood symptoms than other groups. Fear of physical exertion, particularly heavy lifting, persisted across the groups. Some people across all ethnic groups indicated the need for more psychological therapy postcardiac event. Socioeconomic circumstances, age and prior work status appeared to be more important in relation to adaptation after a cardiac event than ethnic status. Conclusions Heterogeneity in views and experiences related to the socioeconomic background, age and work status of the participants along with some cultural influences. Rehabilitation programmes should be flexibly tailored for individuals in particular and where relevant, specific support should be provided for returning to work. PMID:27401355

Ubiquitin-proteasome system impairment caused by a missense cardiac myosin-binding protein C mutation and associated with cardiac dysfunction in hypertrophic cardiomyopathy.

PubMed

Bahrudin, Udin; Morisaki, Hiroko; Morisaki, Takayuki; Ninomiya, Haruaki; Higaki, Katsumi; Nanba, Eiji; Igawa, Osamu; Takashima, Seiji; Mizuta, Einosuke; Miake, Junichiro; Yamamoto, Yasutaka; Shirayoshi, Yasuaki; Kitakaze, Masafumi; Carrier, Lucie; Hisatome, Ichiro

2008-12-26

The ubiquitin-proteasome system is responsible for the disappearance of truncated cardiac myosin-binding protein C, and the suppression of its activity contributes to cardiac dysfunction. This study investigated whether missense cardiac myosin-binding protein C gene (MYBPC3) mutation in hypertrophic cardiomyopathy (HCM) leads to destabilization of its protein, causes UPS impairment, and is associated with cardiac dysfunction. Mutations were identified in Japanese HCM patients using denaturing HPLC and sequencing. Heterologous expression was investigated in COS-7 cells as well as neonatal rat cardiac myocytes to examine protein stability and proteasome activity. The cardiac function was measured using echocardiography. Five novel MYBPC3 mutations -- E344K, DeltaK814, Delta2864-2865GC, Q998E, and T1046M -- were identified in this study. Compared with the wild type and other mutations, the E334K protein level was significantly lower, it was degraded faster, it had a higher level of polyubiquination, and increased in cells pretreated with the proteasome inhibitor MG132 (50 microM, 6 h). The electrical charge of its amino acid at position 334 influenced its stability, but E334K did not affect its phosphorylation. The E334K protein reduced cellular 20 S proteasome activity, increased the proapoptotic/antiapoptotic protein ratio, and enhanced apoptosis in transfected Cos-7 cells and neonatal rat cardiac myocytes. Patients carrying the E334K mutation presented significant left ventricular dysfunction and dilation. The conclusion is the missense MYBPC3 mutation E334K destabilizes its protein through UPS and may contribute to cardiac dysfunction in HCM through impairment of the ubiquitin-proteasome system.

Cloning of a newly identified heart-specific troponin I isoform, which lacks the troponin T binding portion, using the yeast hybrid system.

PubMed

Suzuki, Hideaki; Arakawa, Yasuhiro; Ito, Masaki; Yamada, Hisashi; Horiguchi-Yamada, Junko

2006-01-01

To elucidate the molecular pathogenesis behind increased levels of laminin in cardiac muscle cells in cardiomyopathy by using a yeast hybrid screen. The present study reports the cloning of a newly identified heart-specific troponin I isoform, which is putatively linked to laminin. Future studies will explore the functional significance of this connection. Yeast two-hybrid screen analysis was performed using MLF1-interacting protein (amino acids 1 to 318) as bait. The human heart complementary DNA library was screened by using the yeast-mating method for overnight culture. Two final positive clones from the heart library were isolated. These two clones encoded the same protein, a short isoform of human cardiac troponin I (TnI) that lacked TnI exons 5 and 6. The TnI isoform has a heart-specific expression pattern and it shares several sequence features with human cardiac TnI; however, it lacks the troponin T binding portion. The heart-specific segment of the human cardiac TnI isoform shares several sequence features with human cardiac TnI, but it lacks the troponin T binding portion. These results suggest that the heart-specific TnI isoform may be involved in cardiac development and disease.

Cloning of a newly identified heart-specific troponin I isoform, which lacks the troponin T binding portion, using the yeast hybrid system

PubMed Central

Suzuki, Hideaki; Arakawa, Yasuhiro; Ito, Masaki; Yamada, Hisashi; Horiguchi-Yamada, Junko

2006-01-01

OBJECTIVE To elucidate the molecular pathogenesis behind increased levels of laminin in cardiac muscle cells in cardiomyopathy by using a yeast hybrid screen. The present study reports the cloning of a newly identified heart-specific troponin I isoform, which is putatively linked to laminin. Future studies will explore the functional significance of this connection. METHODS Yeast two-hybrid screen analysis was performed using MLF1-interacting protein (amino acids 1 to 318) as bait. The human heart complementary DNA library was screened by using the yeast-mating method for overnight culture. RESULTS Two final positive clones from the heart library were isolated. These two clones encoded the same protein, a short isoform of human cardiac troponin I (TnI) that lacked TnI exons 5 and 6. The TnI isoform has a heart-specific expression pattern and it shares several sequence features with human cardiac TnI; however, it lacks the troponin T binding portion. CONCLUSION The heart-specific segment of the human cardiac TnI isoform shares several sequence features with human cardiac TnI, but it lacks the troponin T binding portion. These results suggest that the heart-specific TnI isoform may be involved in cardiac development and disease. PMID:18651010

A post-MI power struggle: adaptations in cardiac power occur at the sarcomere level alongside MyBP-C and RLC phosphorylation.

PubMed

Toepfer, Christopher N; Sikkel, Markus B; Caorsi, Valentina; Vydyanath, Anupama; Torre, Iratxe; Copeland, O'Neal; Lyon, Alexander R; Marston, Steven B; Luther, Pradeep K; Macleod, Kenneth T; West, Timothy G; Ferenczi, Michael A

2016-08-01

Myocardial remodeling in response to chronic myocardial infarction (CMI) progresses through two phases, hypertrophic "compensation" and congestive "decompensation." Nothing is known about the ability of uninfarcted myocardium to produce force, velocity, and power during these clinical phases, even though adaptation in these regions likely drives progression of compensation. We hypothesized that enhanced cross-bridge-level contractility underlies mechanical compensation and is controlled in part by changes in the phosphorylation states of myosin regulatory proteins. We induced CMI in rats by left anterior descending coronary artery ligation. We then measured mechanical performance in permeabilized ventricular trabecula taken distant from the infarct zone and assayed myosin regulatory protein phosphorylation in each individual trabecula. During full activation, the compensated myocardium produced twice as much power and 31% greater isometric force compared with noninfarcted controls. Isometric force during submaximal activations was raised >2.4-fold, while power was 2-fold greater. Electron and confocal microscopy demonstrated that these mechanical changes were not a result of increased density of contractile protein and therefore not an effect of tissue hypertrophy. Hence, sarcomere-level contractile adaptations are key determinants of enhanced trabecular mechanics and of the overall cardiac compensatory response. Phosphorylation of myosin regulatory light chain (RLC) increased and remained elevated post-MI, while phosphorylation of myosin binding protein-C (MyBP-C) was initially depressed but then increased as the hearts became decompensated. These sensitivities to CMI are in accordance with phosphorylation-dependent regulatory roles for RLC and MyBP-C in crossbridge function and with compensatory adaptation in force and power that we observed in post-CMI trabeculae. Copyright © 2016 the American Physiological Society.

Point mutations in the tri-helix bundle of the M-domain of cardiac myosin binding protein-C influence systolic duration and delay cardiac relaxation.

PubMed

van Dijk, Sabine J; Kooiker, Kristina B; Napierski, Nathaniel C; Touma, Katia D; Mazzalupo, Stacy; Harris, Samantha P

2018-06-01

Cardiac myosin binding protein-C (cMyBP-C) is an essential regulatory protein required for proper systolic contraction and diastolic relaxation. We previously showed that N'-terminal domains of cMyBP-C stimulate contraction by binding to actin and activating the thin filament in vitro. In principle, thin filament activating effects of cMyBP-C could influence contraction and relaxation rates, or augment force amplitude in vivo. cMyBP-C binding to actin could also contribute to an internal load that slows muscle shortening velocity as previously hypothesized. However, the functional significance of cMyBP-C binding to actin has not yet been established in vivo. We previously identified an actin binding site in the regulatory M-domain of cMyBP-C and described two missense mutations that either increased (L348P) or decreased (E330K) binding affinity of recombinant cMyBP-C N'-terminal domains for actin in vitro. Here we created transgenic mice with either the L348P or E330K mutations to determine the functional significance of cMyBP-C binding to actin in vivo. Results showed that enhanced binding of cMyBP-C to actin in L348P-Tg mice prolonged the time to end-systole and slowed relaxation rates. Reduced interactions between cMyBP-C and actin in E330K-Tg mice had the opposite effect and significantly shortened the duration of ejection. Neither mouse model displayed overt systolic dysfunction, but L348P-Tg mice showed diastolic dysfunction presumably resulting from delayed relaxation. We conclude that cMyBP-C binding to actin contributes to sustained thin filament activation at the end of systole and during isovolumetric relaxation. These results provide the first functional evidence that cMyBP-C interactions with actin influence cardiac function in vivo. Copyright © 2018 Elsevier Ltd. All rights reserved.

Transgenic Analysis of the Role of FKBP12.6 in Cardiac Function and Intracellular Calcium Release

PubMed Central

Liu, Ying; Chen, Hanying; Ji, Guangju; Li, Baiyan; Mohler, Peter J.; Zhu, Zhiming; Yong, Weidong; Chen, Zhuang; Xu, Xuehong

2011-01-01

Abstract FK506 binding protein12.6 (FKBP12.6) binds to the Ca2+ release channel ryanodine receptor (RyR2) in cardiomyocytes and stabilizes RyR2 to prevent premature sarcoplasmic reticulum Ca2+ release. Previously, two different mouse strains deficient in FKBP12.6 were reported to have different abnormal cardiac phenotypes. The first mutant strain displayed sex-dependent cardiac hypertrophy, while the second displayed exercise-induced cardiac arrhythmia and sudden death. In this study, we tested whether FKBP12.6-deficient mice that display hypertrophic hearts can develop exercise-induced cardiac sudden death and whether the hypertrophic heart is a direct consequence of abnormal calcium handling in mutant cardiomyocytes. Our data show that FKBP12.6-deficient mice with cardiac hypertrophy do not display exercise-induced arrhythmia and/or sudden cardiac death. To investigate the role of FKBP12.6 overexpression for cardiac function and cardiomyocyte calcium release, we generated a transgenic mouse line with cardiac specific overexpression of FKBP12.6 using α-myosin heavy chain (αMHC) promoter. MHC-FKBP12.6 mice displayed normal cardiac development and function. We demonstrated that MHC-FKBP12.6 mice are able to rescue abnormal cardiac hypertrophy and abnormal calcium release in FKBP12.6-deficient mice. PMID:22087651

(/sup 3/H)forskolin- and (/sup 3/H)dihydroalprenolol-binding sites and adenylate cyclase activity in heart of rats fed diets containing different oils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alam, S.Q.; Ren, Y.F.; Alam, B.S.

1988-03-01

The characteristics of the cardiac adenylate cyclase system were studied in rats fed diets containing fish oil (menhaden oil) and other oils. Adenylate cyclase activity generally was higher in cardiac homogenates and membranes of rats fed diet containing 10% menhaden oil than in the other oils. The increase in enzyme activity, especially in forskolin-stimulated activity, was associated with an increase in the concentration of the (/sup 3/H) forskolin-binding sites in cardiac membranes of rats fed menhaden oil. The beta-adrenergic receptor concentration was not significantly altered although the affinity for (/sup 3/H)dihydroalprenolol-binding was lower in membranes of rats fed menhaden oilmore » than those fed the other oils. omega-3 fatty acids from menhaden oil were incorporated into the cardiac membrane phospholipids. The results suggest that the observed increase in myocardial adenylate cyclase activity of rats fed menhaden oil may be due to an increase in the number of the catalytic subunits of the enzyme or due to a greater availability of the forskolin-binding sites.« less

Genome-Wide Screens for In Vivo Tinman Binding Sites Identify Cardiac Enhancers with Diverse Functional Architectures

PubMed Central

Jin, Hong; Stojnic, Robert; Adryan, Boris; Ozdemir, Anil; Stathopoulos, Angelike; Frasch, Manfred

2013-01-01

The NK homeodomain factor Tinman is a crucial regulator of early mesoderm patterning and, together with the GATA factor Pannier and the Dorsocross T-box factors, serves as one of the key cardiogenic factors during specification and differentiation of heart cells. Although the basic framework of regulatory interactions driving heart development has been worked out, only about a dozen genes involved in heart development have been designated as direct Tinman target genes to date, and detailed information about the functional architectures of their cardiac enhancers is lacking. We have used immunoprecipitation of chromatin (ChIP) from embryos at two different stages of early cardiogenesis to obtain a global overview of the sequences bound by Tinman in vivo and their linked genes. Our data from the analysis of ∼50 sequences with high Tinman occupancy show that the majority of such sequences act as enhancers in various mesodermal tissues in which Tinman is active. All of the dorsal mesodermal and cardiac enhancers, but not some of the others, require tinman function. The cardiac enhancers feature diverse arrangements of binding motifs for Tinman, Pannier, and Dorsocross. By employing these cardiac and non-cardiac enhancers in machine learning approaches, we identify a novel motif, termed CEE, as a classifier for cardiac enhancers. In vivo assays for the requirement of the binding motifs of Tinman, Pannier, and Dorsocross, as well as the CEE motifs in a set of cardiac enhancers, show that the Tinman sites are essential in all but one of the tested enhancers; although on occasion they can be functionally redundant with Dorsocross sites. The enhancers differ widely with respect to their requirement for Pannier, Dorsocross, and CEE sites, which we ascribe to their different position in the regulatory circuitry, their distinct temporal and spatial activities during cardiogenesis, and functional redundancies among different factor binding sites. PMID:23326246

Short-term adaptation and chronic cardiac remodelling to high altitude in lowlander natives and Himalayan Sherpa.

PubMed

Stembridge, Mike; Ainslie, Philip N; Shave, Rob

2015-11-01

What is the topic of this review? At high altitude, the cardiovascular system must adapt in order to meet the metabolic demand for oxygen. This review summarizes recent findings relating to short-term and life-long cardiac adaptation to high altitude in the context of exercise capacity. What advances does it highlight? Both Sherpa and lowlanders exhibit smaller left ventricular volumes at high altitude; however, myocardial relaxation, as evidenced by diastolic untwist, is reduced only in Sherpa, indicating that short-term hypoxia does not impair diastolic relaxation. Potential remodelling of systolic function, as evidenced by lower left ventricular systolic twist in Sherpa, may facilitate the requisite sea-level mechanical reserve required during exercise, although this remains to be confirmed. Both short-term and life-long high-altitude exposure challenge the cardiovascular system to meet the metabolic demand for O2 in a hypoxic environment. As the demand for O2 delivery increases during exercise, the circulatory component of oxygen transport is placed under additional stress. Acute adaptation and chronic remodelling of cardiac structure and function may occur to facilitate O2 delivery in lowlanders during sojourn to high altitude and in permanent highland residents. However, our understanding of cardiac structural and functional adaption in Sherpa remains confined to a higher maximal heart rate, lower pulmonary vascular resistance and no differences in resting cardiac output. Ventricular form and function are intrinsically linked through the left ventricular (LV) mechanics that facilitate efficient ejection, minimize myofibre stress during contraction and aid diastolic recoil. Recent examination of LV mechanics has allowed detailed insight into fundamental cardiac adaptation in high-altitude Sherpa. In this symposium report, we review recent advances in our understanding of LV function in both lowlanders and Sherpa at rest and discuss the potential consequences for exercise capacity. Collectively, data indicate chronic structural ventricular adaptation, with adult Sherpa having smaller absolute and relative LV size. Consistent with structural remodelling, cardiac mechanics also differ in Sherpa when compared with lowlanders at high altitude. These differences are characterized by a reduction in resting systolic deformation and slower diastolic untwisting, a surrogate of relaxation. These changes may reflect a functional cardiac adaptation that affords Sherpa the same mechanical reserve seen in lowlanders at sea level, which is absent when they ascend to high altitude. © 2014 The Authors. Experimental Physiology © 2014 The Physiological Society.

An endogenously produced fragment of cardiac myosin-binding protein C is pathogenic and can lead to heart failure.

PubMed

Razzaque, Md Abdur; Gupta, Manish; Osinska, Hanna; Gulick, James; Blaxall, Burns C; Robbins, Jeffrey

2013-08-16

A stable 40-kDa fragment is produced from cardiac myosin-binding protein C when the heart is stressed using a stimulus, such as ischemia-reperfusion injury. Elevated levels of the fragment can be detected in the diseased mouse and human heart, but its ability to interfere with normal cardiac function in the intact animal is unexplored. To understand the potential pathogenicity of the 40-kDa fragment in vivo and to investigate the molecular pathways that could be targeted for potential therapeutic intervention. We generated cardiac myocyte-specific transgenic mice using a Tet-Off inducible system to permit controlled expression of the 40-kDa fragment in cardiomyocytes. When expression of the 40-kDa protein is induced by crossing the responder animals with tetracycline transactivator mice under conditions in which substantial quantities approximating those observed in diseased hearts are reached, the double-transgenic mice subsequently experience development of sarcomere dysgenesis and altered cardiac geometry, and the heart fails between 12 and 17 weeks of age. The induced double-transgenic mice had development of cardiac hypertrophy with myofibrillar disarray and fibrosis, in addition to activation of pathogenic MEK-ERK pathways. Inhibition of MEK-ERK signaling was achieved by injection of the mitogen-activated protein kinase (MAPK)/ERK inhibitor U0126. The drug effectively improved cardiac function, normalized heart size, and increased probability of survival. These results suggest that the 40-kDa cardiac myosin-binding protein C fragment, which is produced at elevated levels during human cardiac disease, is a pathogenic fragment that is sufficient to cause hypertrophic cardiomyopathy and heart failure.

Integrin activation and focal complex formation in cardiac hypertrophy.

PubMed

Laser, M; Willey, C D; Jiang, W; Cooper, G; Menick, D R; Zile, M R; Kuppuswamy, D

2000-11-10

Cardiac hypertrophy is characterized by both remodeling of the extracellular matrix (ECM) and hypertrophic growth of the cardiocytes. Here we show increased expression and cytoskeletal association of the ECM proteins fibronectin and vitronectin in pressure-overloaded feline myocardium. These changes are accompanied by cytoskeletal binding and phosphorylation of focal adhesion kinase (FAK) at Tyr-397 and Tyr-925, c-Src at Tyr-416, recruitment of the adapter proteins p130(Cas), Shc, and Nck, and activation of the extracellular-regulated kinases ERK1/2. A synthetic peptide containing the Arg-Gly-Asp (RGD) motif of fibronectin and vitronectin was used to stimulate adult feline cardiomyocytes cultured on laminin or within a type-I collagen matrix. Whereas cardiocytes under both conditions showed RGD-stimulated ERK1/2 activation, only collagen-embedded cells exhibited cytoskeletal assembly of FAK, c-Src, Nck, and Shc. In RGD-stimulated collagen-embedded cells, FAK was phosphorylated only at Tyr-397 and c-Src association occurred without Tyr-416 phosphorylation and p130(Cas) association. Therefore, c-Src activation is not required for its cytoskeletal binding but may be important for additional phosphorylation of FAK. Overall, our study suggests that multiple signaling pathways originate in pressure-overloaded heart following integrin engagement with ECM proteins, including focal complex formation and ERK1/2 activation, and many of these pathways can be activated in cardiomyocytes via RGD-stimulated integrin activation.

Integrin activation and focal complex formation in cardiac hypertrophy

NASA Technical Reports Server (NTRS)

Laser, M.; Willey, C. D.; Jiang, W.; Cooper, G. 4th; Menick, D. R.; Zile, M. R.; Kuppuswamy, D.

2000-01-01

Cardiac hypertrophy is characterized by both remodeling of the extracellular matrix (ECM) and hypertrophic growth of the cardiocytes. Here we show increased expression and cytoskeletal association of the ECM proteins fibronectin and vitronectin in pressure-overloaded feline myocardium. These changes are accompanied by cytoskeletal binding and phosphorylation of focal adhesion kinase (FAK) at Tyr-397 and Tyr-925, c-Src at Tyr-416, recruitment of the adapter proteins p130(Cas), Shc, and Nck, and activation of the extracellular-regulated kinases ERK1/2. A synthetic peptide containing the Arg-Gly-Asp (RGD) motif of fibronectin and vitronectin was used to stimulate adult feline cardiomyocytes cultured on laminin or within a type-I collagen matrix. Whereas cardiocytes under both conditions showed RGD-stimulated ERK1/2 activation, only collagen-embedded cells exhibited cytoskeletal assembly of FAK, c-Src, Nck, and Shc. In RGD-stimulated collagen-embedded cells, FAK was phosphorylated only at Tyr-397 and c-Src association occurred without Tyr-416 phosphorylation and p130(Cas) association. Therefore, c-Src activation is not required for its cytoskeletal binding but may be important for additional phosphorylation of FAK. Overall, our study suggests that multiple signaling pathways originate in pressure-overloaded heart following integrin engagement with ECM proteins, including focal complex formation and ERK1/2 activation, and many of these pathways can be activated in cardiomyocytes via RGD-stimulated integrin activation.

Cardiovascular Adaptations Induced by Resistance Training in Animal Models.

PubMed

Melo, S F S; da Silva Júnior, N D; Barauna, V G; Oliveira, E M

2018-01-01

In the last 10 years the number of studies showing the benefits of resistance training (RT) to the cardiovascular system, have grown. In comparison to aerobic training, RT-induced favorable adaptations to the cardiovascular system have been ignored for many years, thus the mechanisms of the RT-induced cardiovascular adaptations are still uncovered. The lack of animal models with comparable protocols to the RT performed by humans hampers the knowledge. We have used squat-exercise model, which is widely used by many others laboratories. However, to a lesser extent, other models are also employed to investigate the cardiovascular adaptations. In the subsequent sections we will review the information regarding cardiac morphological adaptations, signaling pathway of the cardiac cell, cardiac function and the vascular adaptation induced by RT using this animal model developed by Tamaki et al. in 1992. Furthermore, we also describe cardiovascular findings observed using other animal models of RT.

Peri-operative heart-type fatty acid binding protein is associated with acute kidney injury after cardiac surgery

PubMed Central

Schaub, Jennifer A.; Garg, Amit X.; Coca, Steven G.; Testani, Jeffrey M.; Shlipak, Michael G.; Eikelboom, John; Kavsak, Peter; McArthur, Eric; Shortt, Colleen; Whitlock, Richard; Parikh, Chirag R.

2015-01-01

Acute Kidney Injury (AKI) is a common complication after cardiac surgery and is associated with worse outcomes. Since heart fatty acid binding protein (H-FABP) is a myocardial protein that detects cardiac injury, we sought to determine if plasma H-FABP was associated with AKI in the TRIBE-AKI cohort; a multi-center cohort of 1219 patients at high risk for AKI who underwent cardiac surgery. The primary outcomes of interest were any AKI (Acute Kidney Injury Network (AKIN) stage 1 or higher) and severe AKI (AKIN stage 2 or higher). The secondary outcome was long-term mortality after discharge. Patients who developed AKI had higher levels of H-FABP pre- and post-operatively than patients who did not have AKI. In analyses adjusted for known AKI risk factors, first post-operative log(H-FABP) was associated with severe AKI (adjusted OR 5.39 [95% CI, 2.87-10.11] per unit increase), while pre-operative log(H-FABP) was associated with any AKI (2.07 [1.48-2.89]) and mortality (1.67 [1.17-2.37]). These relationships persisted after adjustment for change in serum creatinine (for first postoperative log(H-FABP)) and biomarkers of cardiac and kidney injury, including brain natriuretic peptide, cardiac troponin-I, interleukin-18, liver fatty acid binding protein, kidney injury molecule-1, and neutrophil gelatinase associated lipocalin. Thus, peri-operative plasma H-FABP levels may be used for risk-stratification of AKI and mortality following cardiac surgery. PMID:25830762

Flecainide attenuates rate adaptation of ventricular repolarization in guinea-pig heart.

PubMed

Osadchii, Oleg E

2016-01-01

Flecainide is class Ic antiarrhythmic agent that was found to increase the risk of sudden cardiac death. Arrhythmic responses to flecainide could be precipitated by exercise, suggesting a role played by inappropriate rate adaptation of ventricular repolarization. This study therefore examined flecainide effect on adaptation of the QT interval and ventricular action potential duration (APD) to abrupt reductions of the cardiac cycle length. ECG and ventricular epicardial and endocardial monophasic APD were recorded in isolated, perfused guinea-pig heart preparations upon a sustained cardiac acceleration (rapid pacing for 30 s), and following a single perturbation of the cycle length evoked by extrasystolic stimulation. Sustained increase in heart rate was associated with progressive bi-exponential shortening of the QT interval and APD. Flecainide prolonged ventricular repolarization, delayed its rate adaptation, and decreased the amplitude of QT interval and APD shortening upon rapid cardiac pacing. During extrasystolic stimulation, flecainide attenuated APD shortening in premature ventricular beats, with effect being greater upon using a longer basic drive cycle length (S1-S1=550 ms versus S1-S1=300 ms). Flecainide-induced arrhythmia may be partly accounted for by attenuated adaptation of ventricular repolarization to sudden changes in cardiac cycle length provoked by transient tachycardia or ectopic beats.

Impact of ethnicity on cardiac adaptation to exercise.

PubMed

Sheikh, Nabeel; Sharma, Sanjay

2014-04-01

The increasing globalization of sport has resulted in athletes from a wide range of ethnicities emerging onto the world stage. Fuelled by the untimely death of a number of young professional athletes, data generated from the parallel increase in preparticipation cardiovascular evaluation has indicated that ethnicity has a substantial influence on cardiac adaptation to exercise. From this perspective, the group most intensively studied comprises athletes of African or Afro-Caribbean ethnicity (black athletes), an ever-increasing number of whom are competing at the highest levels of sport and who often exhibit profound electrical and structural cardiac changes in response to exercise. Data on other ethnic cohorts are emerging, but remain incomplete. This Review describes our current knowledge on the impact of ethnicity on cardiac adaptation to exercise, starting with white athletes in whom the physiological electrical and structural changes--collectively termed the 'athlete's heart'--were first described. Discussion of the differences in the cardiac changes between ethnicities, with a focus on black athletes, and of the challenges that these variations can produce for the evaluating physician is also provided. The impact of ethnically mediated changes on preparticipation cardiovascular evaluation is highlighted, particularly with respect to false positive results, and potential genetic mechanisms underlying racial differences in cardiac adaptation to exercise are described.

Cardiac size of high-volume resistance trained female athletes: shaping the body but not the heart.

PubMed

Venckunas, T; Simonavicius, J; Marcinkeviciene, J E

2016-03-01

Introduction Exercise training, besides many health benefits, may result in cardiac remodelling which is dependent on the type and amount of exercise performed. It is not clear, however, whether significant adaptation in cardiac structure is possible in females undergoing resistance type of exercise training. Rigorous high volume training of most muscle groups emphasising resistance exercises are being undertaken by athletes of some aesthetic sports such as female fitness (light bodybuilding). The impact of this type of training on cardiac adaptation has not been investigated until now. The aim of the current study was to disclose the effect of high volume resistance training on cardiac structure and function. Methods 11 top-level female fitness athletes and 20 sedentary age-matched controls were recruited to undergo two-dimensional echocardiography. Results Cardiac structure did not differ between elite female fitness athletes and controls (p > 0.05), and fitness athletes had a tendency for a smaller (p = 0.07) left ventricular (LV) mass indexed to lean body mass. Doppler diastolic function index (E/A ratio) and LV ejection fraction were similar between the groups (p > 0.05). Conclusions Elite female fitness athletes have normal cardiac size and function that do not differ from matched sedentary controls. Consequently, as high volume resistance training has no easily observable effect on adaptation of cardiac structure, when cardiac hypertrophy is present in young resistance-trained lean female, other reasons such as inherited cardiac disease are to be considered carefully.

Differential and Conditional Activation of PKC-Isoforms Dictates Cardiac Adaptation during Physiological to Pathological Hypertrophy

PubMed Central

Naskar, Shaon; Datta, Kaberi; Mitra, Arkadeep; Pathak, Kanchan; Datta, Ritwik; Bansal, Trisha; Sarkar, Sagartirtha

2014-01-01

A cardiac hypertrophy is defined as an increase in heart mass which may either be beneficial (physiological hypertrophy) or detrimental (pathological hypertrophy). This study was undertaken to establish the role of different protein kinase-C (PKC) isoforms in the regulation of cardiac adaptation during two types of cardiac hypertrophy. Phosphorylation of specific PKC-isoforms and expression of their downstream proteins were studied during physiological and pathological hypertrophy in 24 week male Balb/c mice (Mus musculus) models, by reverse transcriptase-PCR, western blot analysis and M-mode echocardiography for cardiac function analysis. PKC-δ was significantly induced during pathological hypertrophy while PKC-α was exclusively activated during physiological hypertrophy in our study. PKC-δ activation during pathological hypertrophy resulted in cardiomyocyte apoptosis leading to compromised cardiac function and on the other hand, activation of PKC-α during physiological hypertrophy promoted cardiomyocyte growth but down regulated cellular apoptotic load resulting in improved cardiac function. Reversal in PKC-isoform with induced activation of PKC-δ and simultaneous inhibition of phospho-PKC-α resulted in an efficient myocardium to deteriorate considerably resulting in compromised cardiac function during physiological hypertrophy via augmentation of apoptotic and fibrotic load. This is the first report where PKC-α and -δ have been shown to play crucial role in cardiac adaptation during physiological and pathological hypertrophy respectively thereby rendering compromised cardiac function to an otherwise efficient heart by conditional reversal of their activation. PMID:25116170

Exploration of the psychological impact and adaptation to cardiac events in South Asians in the UK: a qualitative study.

PubMed

Bhattacharyya, Mimi; Stevenson, Fiona; Walters, Kate

2016-07-08

There is little research on how different ethnic groups adapt after an acute cardiac event. This qualitative study explores between-ethnicity and within-ethnicity variation in adaptation, and the psychological impact of an acute cardiac event among UK South Asian and white British people. We purposively sampled people by ethnic group from general practices in London who had a new myocardial infarction, angina or acute arrhythmia in the preceding 18 months. We conducted 28 semistructured interviews for exploring the psychological symptoms, experiences and adaptations following a cardiac event among South Asians (Indian and Bangladeshi) in comparison to white British people. Data were analysed using a thematic 'framework' approach. Findings showed heterogeneity in experiences of the cardiac event and its subsequent psychological and physical impact. Adaptation to the event related predominantly to life circumstances, personal attitudes and employment status. Anxiety and low mood symptoms were common sequelae, especially in the Bangladeshi group. Indian men tended to normalise symptoms and the cardiac event, and reported less negative mood symptoms than other groups. Fear of physical exertion, particularly heavy lifting, persisted across the groups. Some people across all ethnic groups indicated the need for more psychological therapy postcardiac event. Socioeconomic circumstances, age and prior work status appeared to be more important in relation to adaptation after a cardiac event than ethnic status. Heterogeneity in views and experiences related to the socioeconomic background, age and work status of the participants along with some cultural influences. Rehabilitation programmes should be flexibly tailored for individuals in particular and where relevant, specific support should be provided for returning to work. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

MOF Acetyl Transferase Regulates Transcription and Respiration in Mitochondria.

PubMed

Chatterjee, Aindrila; Seyfferth, Janine; Lucci, Jacopo; Gilsbach, Ralf; Preissl, Sebastian; Böttinger, Lena; Mårtensson, Christoph U; Panhale, Amol; Stehle, Thomas; Kretz, Oliver; Sahyoun, Abdullah H; Avilov, Sergiy; Eimer, Stefan; Hein, Lutz; Pfanner, Nikolaus; Becker, Thomas; Akhtar, Asifa

2016-10-20

A functional crosstalk between epigenetic regulators and metabolic control could provide a mechanism to adapt cellular responses to environmental cues. We report that the well-known nuclear MYST family acetyl transferase MOF and a subset of its non-specific lethal complex partners reside in mitochondria. MOF regulates oxidative phosphorylation by controlling expression of respiratory genes from both nuclear and mtDNA in aerobically respiring cells. MOF binds mtDNA, and this binding is dependent on KANSL3. The mitochondrial pool of MOF, but not a catalytically deficient mutant, rescues respiratory and mtDNA transcriptional defects triggered by the absence of MOF. Mof conditional knockout has catastrophic consequences for tissues with high-energy consumption, triggering hypertrophic cardiomyopathy and cardiac failure in murine hearts; cardiomyocytes show severe mitochondrial degeneration and deregulation of mitochondrial nutrient metabolism and oxidative phosphorylation pathways. Thus, MOF is a dual-transcriptional regulator of nuclear and mitochondrial genomes connecting epigenetics and metabolism. Copyright © 2016 Elsevier Inc. All rights reserved.

Recurrent myocardial infarction: Mechanisms of free-floating adaptation and autonomic derangement in networked cardiac neural control.

PubMed

Kember, Guy; Ardell, Jeffrey L; Shivkumar, Kalyanam; Armour, J Andrew

2017-01-01

The cardiac nervous system continuously controls cardiac function whether or not pathology is present. While myocardial infarction typically has a major and catastrophic impact, population studies have shown that longer-term risk for recurrent myocardial infarction and the related potential for sudden cardiac death depends mainly upon standard atherosclerotic variables and autonomic nervous system maladaptations. Investigative neurocardiology has demonstrated that autonomic control of cardiac function includes local circuit neurons for networked control within the peripheral nervous system. The structural and adaptive characteristics of such networked interactions define the dynamics and a new normal for cardiac control that results in the aftermath of recurrent myocardial infarction and/or unstable angina that may or may not precipitate autonomic derangement. These features are explored here via a mathematical model of cardiac regulation. A main observation is that the control environment during pathology is an extrapolation to a setting outside prior experience. Although global bounds guarantee stability, the resulting closed-loop dynamics exhibited while the network adapts during pathology are aptly described as 'free-floating' in order to emphasize their dependence upon details of the network structure. The totality of the results provide a mechanistic reasoning that validates the clinical practice of reducing sympathetic efferent neuronal tone while aggressively targeting autonomic derangement in the treatment of ischemic heart disease.

[The influence of cardiosurgical intervention type and conditions of artificial blood circulation of perioperative dynamics of cardiac biomarkers].

PubMed

Dement'eva, I I; Morozov, Iu A; Charnaia, M A

2013-01-01

125 patients after cardiac surgery operated on with the use of artificial blood circulation (ABC) were followed-up. Blood levels of cardiac protein, binding aliphatic acids and troponin 1 and 3 days after the operation were registered. The study showed that aorta clamping more then 90 minutes and hypothermic perfusion regimen influence cardiomyocites negatively. The state of "surgical trauma" and reperfusional myocardium damage was approximately the same during aortic surgery, myocardium revascularization with the use of aortic clamping and cardioplegia, and correction of the acquired heart disease, according to the dynamics of the studied proteins in blood. The minimal blood level of cardiac protein, binding aliphatic acids after coronary by-pass surgery on the working heart witnesses about negative influence of crystalloid hypothermic cardioplegia on coronary microcirculation.

Analysis of IR spectra of mineralized deposits on human cardiac valves

NASA Astrophysics Data System (ADS)

Ivanov-Omskii, V. I.; Yastrebov, S. G.; Gulyaev, N. I.

2017-05-01

IR spectroscopy in the range of vibration of hydroxy groups has been used to analyze the binding energy of mineralized deposits to cardiac valves of patients of varied gender and age. A tendency was revealed toward a gender-independent rise in the binding energy of mineralized deposits to valve tissues with increasing age of patients. The analysis enables making recommendations concerning the early diagnostics of valve calcination, monitoring of its development, and therapy of calcinoses.

Phosphorylation of cardiac myosin binding protein C releases myosin heads from the surface of cardiac thick filaments

PubMed Central

Kensler, Robert W.; Craig, Roger; Moss, Richard L.

2017-01-01

Cardiac myosin binding protein C (cMyBP-C) has a key regulatory role in cardiac contraction, but the mechanism by which changes in phosphorylation of cMyBP-C accelerate cross-bridge kinetics remains unknown. In this study, we isolated thick filaments from the hearts of mice in which the three serine residues (Ser273, Ser282, and Ser302) that are phosphorylated by protein kinase A in the m-domain of cMyBP-C were replaced by either alanine or aspartic acid, mimicking the fully nonphosphorylated and the fully phosphorylated state of cMyBP-C, respectively. We found that thick filaments from the cMyBP-C phospho-deficient hearts had highly ordered cross-bridge arrays, whereas the filaments from the cMyBP-C phospho-mimetic hearts showed a strong tendency toward disorder. Our results support the hypothesis that dephosphorylation of cMyBP-C promotes or stabilizes the relaxed/superrelaxed quasi-helical ordering of the myosin heads on the filament surface, whereas phosphorylation weakens this stabilization and binding of the heads to the backbone. Such structural changes would modulate the probability of myosin binding to actin and could help explain the acceleration of cross-bridge interactions with actin when cMyBP-C is phosphorylated because of, for example, activation of β1-adrenergic receptors in myocardium. PMID:28167762

Phosphorylation of cardiac myosin binding protein C releases myosin heads from the surface of cardiac thick filaments.

PubMed

Kensler, Robert W; Craig, Roger; Moss, Richard L

2017-02-21

Cardiac myosin binding protein C (cMyBP-C) has a key regulatory role in cardiac contraction, but the mechanism by which changes in phosphorylation of cMyBP-C accelerate cross-bridge kinetics remains unknown. In this study, we isolated thick filaments from the hearts of mice in which the three serine residues (Ser273, Ser282, and Ser302) that are phosphorylated by protein kinase A in the m-domain of cMyBP-C were replaced by either alanine or aspartic acid, mimicking the fully nonphosphorylated and the fully phosphorylated state of cMyBP-C, respectively. We found that thick filaments from the cMyBP-C phospho-deficient hearts had highly ordered cross-bridge arrays, whereas the filaments from the cMyBP-C phospho-mimetic hearts showed a strong tendency toward disorder. Our results support the hypothesis that dephosphorylation of cMyBP-C promotes or stabilizes the relaxed/superrelaxed quasi-helical ordering of the myosin heads on the filament surface, whereas phosphorylation weakens this stabilization and binding of the heads to the backbone. Such structural changes would modulate the probability of myosin binding to actin and could help explain the acceleration of cross-bridge interactions with actin when cMyBP-C is phosphorylated because of, for example, activation of β 1 -adrenergic receptors in myocardium.

All human Na(+)-K(+)-ATPase alpha-subunit isoforms have a similar affinity for cardiac glycosides.

PubMed

Wang, J; Velotta, J B; McDonough, A A; Farley, R A

2001-10-01

Three alpha-subunit isoforms of the sodium pump, which is the receptor for cardiac glycosides, are expressed in human heart. The aim of this study was to determine whether these isoforms have distinct affinities for the cardiac glycoside ouabain. Equilibrium ouabain binding to membranes from a panel of different human tissues and cell lines derived from human tissues was compared by an F statistic to determine whether a single population of binding sites or two populations of sites with different affinities would better fit the data. For all tissues, the single-site model fit the data as well as the two-site model. The mean equilibrium dissociation constant (K(d)) for all samples calculated using the single-site model was 18 +/- 6 nM (mean +/- SD). No difference in K(d) was found between nonfailing and failing human heart samples, although the maximum number of binding sites in failing heart was only approximately 50% of the number of sites in nonfailing heart. Measurement of association rate constants and dissociation rate constants confirmed that the binding affinities of the different human alpha-isoforms are similar to each other, although calculated K(d) values were lower than those determined by equilibrium binding. These results indicate both that the affinity of all human alpha-subunit isoforms for ouabain is similar and that the increased sensitivity of failing human heart to cardiac glycosides is probably due to a reduction in the number of pumps in the heart rather than to a selective inhibition of a subset of pumps with different affinities for the drugs.

Cardiac distribution of the binding sites for natriuretic peptides in vertebrates.

PubMed

Cerra, M C

1994-12-01

Natriuretic peptides are hormones that play an important role in the cardiovascular control of mammalian and non-mammalian vertebrates. They have been classified into four groups. Of these, ANP (atrial natriuretic peptide), BNP (brain atriuretic peptides), CNP (C-type natriuretic peptide) are detected in cardiac and non cardiac tissues of all vertebrates; while VNP (ventricular natriuretic peptide) has been isolated only from the fish ventricle. All peptides have shown a high degree of sequence homology. The expression of the three principal types of natriuretic peptide (ANP, BNP and CNP) in cardiac tissues is developmentally and functionally regulated in a highly tissue-specific manner. Three types of natriuretic peptide receptors have been identified in numerous target tissues. Two receptors are transmembrane guanylyl cyclases (ANPR-A and ANPR-B) that mediate biological effects of natriuretic peptides; the third one (ANPR-C) has no guanylyl cyclase and is called "clearance receptor." The presence of natriuretic peptide binding sites in the heart suggests new aspects of paracrine control of cardiac function. A relevant localization of natriuretic peptide receptors was found in those cardiac regions particularly suitable for monitoring blood volume and pressure oscillations such as the inflow tract and the outflow tract. For example, in birds (quail) the highest levels of natriuretic peptide receptors were detected in the inflow tract represented by the vena cava. In both fish and birds, the outflow chamber, the bulbus cordis, had a high number of natriuretic peptide binding sites. In mammals, a remarkable concentration of natriuretic peptide receptors was also observed in the coronary vessels. This zoning of cardiac natriuretic peptide receptors indicates an intracardiac action of the hormones and adds a humoral dimension to the morphofunctional design of the vertebrate heart.

Thermal adaptation of the crucian carp (Carassius carassius) cardiac delayed rectifier current, IKs, by homomeric assembly of Kv7.1 subunits without MinK.

PubMed

Hassinen, Minna; Laulaja, Salla; Paajanen, Vesa; Haverinen, Jaakko; Vornanen, Matti

2011-07-01

Ectothermic vertebrates experience acute and chronic temperature changes which affect cardiac excitability and may threaten electrical stability of the heart. Nevertheless, ectothermic hearts function over wide range of temperatures without cardiac arrhythmias, probably due to special molecular adaptations. We examine function and molecular basis of the slow delayed rectifier K(+) current (I(Ks)) in cardiac myocytes of a eurythermic fish (Carassius carassius L.). I(Ks) is an important repolarizing current that prevents excessive prolongation of cardiac action potential, but it is extremely slowly activating when expressed in typical molecular composition of the endothermic animals. Comparison of the I(Ks) of the crucian carp atrial myocytes with the currents produced by homomeric K(v)7.1 and heteromeric K(v)7.1/MinK channels in Chinese hamster ovary cells indicates that activation kinetics and pharmacological properties of the I(Ks) are similar to those of the homomeric K(v)7.1 channels. Consistently with electrophysiological properties and homomeric K(v)7.1 channel composition, atrial transcript expression of the MinK subunit is only 1.6-1.9% of the expression level of the K(v)7.1 subunit. Since activation kinetics of the homomeric K(v)7.1 channels is much faster than activation of the heteromeric K(v)7.1/MinK channels, the homomeric K(v)7.1 composition of the crucian carp cardiac I(Ks) is thermally adaptive: the slow delayed rectifier channels can open despite low body temperatures and curtail the duration of cardiac action potential in ectothermic crucian carp. We suggest that the homomeric K(v)7.1 channel assembly is an evolutionary thermal adaptation of ectothermic hearts and the heteromeric K(v)7.1/MinK channels evolved later to adapt I(Ks) to high body temperature of endotherms.

Dexamethasone effects on creatine kinase activity and insulin-like growth factor receptors in cultured muscle cells

NASA Technical Reports Server (NTRS)

Whitson, Peggy A.; Stuart, Charles A.; Huls, M. H.; Sams, Clarence F.; Cintron, Nitza M.

1989-01-01

The effect of dexamethasone on the activity of creatine kinase (CK) and the insulin-like growth factor I (IGF-I) binding were investigated using skeletal- and cardiac-muscle-derived cultured cell lines (mouse, C2C12; rat, L6 and H9c2). It was found that, in skeletal muscle cells, dexamethasone treatment during differentiation of skeletal-muscle cells caused dose-dependent increases in CK activity and increases in the degree of myotube formation, whereas cardiac cells (H9c2) exhibited very low CK activity during culture or dexamethasone treatment. Results for IGF-I binding were similar in all three cell lines. The IGF-I binding to dexamethasone-treated cells (50 nM for 24 hr on the day prior to confluence) resulted in an increased number of available binding sites, with no effect on the binding affinities.

NADPH oxidase-4 mediates protection against chronic load-induced stress in mouse hearts by enhancing angiogenesis

PubMed Central

Zhang, Min; Brewer, Alison C.; Schröder, Katrin; Santos, Celio X. C.; Grieve, David J.; Wang, Minshu; Anilkumar, Narayana; Yu, Bin; Dong, Xuebin; Walker, Simon J.; Brandes, Ralf P.; Shah, Ajay M.

2010-01-01

Cardiac failure occurs when the heart fails to adapt to chronic stresses. Reactive oxygen species (ROS)-dependent signaling is implicated in cardiac stress responses, but the role of different ROS sources remains unclear. Here we report that NADPH oxidase-4 (Nox4) facilitates cardiac adaptation to chronic stress. Unlike other Nox proteins, Nox4 activity is regulated mainly by its expression level, which increases in cardiomyocytes under stresses such as pressure overload or hypoxia. To investigate the functional role of Nox4 during the cardiac response to stress, we generated mice with a genetic deletion of Nox4 or a cardiomyocyte-targeted overexpression of Nox4. Basal cardiac function was normal in both models, but Nox4-null animals developed exaggerated contractile dysfunction, hypertrophy, and cardiac dilatation during exposure to chronic overload whereas Nox4-transgenic mice were protected. Investigation of mechanisms underlying this protective effect revealed a significant Nox4-dependent preservation of myocardial capillary density after pressure overload. Nox4 enhanced stress-induced activation of cardiomyocyte hypoxia inducible factor 1 and the release of vascular endothelial growth factor, resulting in increased paracrine angiogenic activity. These data indicate that cardiomyocyte Nox4 is a unique inducible regulator of myocardial angiogenesis, a key determinant of cardiac adaptation to overload stress. Our results also have wider relevance to the use of nonspecific antioxidant approaches in cardiac disease and may provide an explanation for the failure of such strategies in many settings. PMID:20921387

Diabetic db/db mice do not develop heart failure upon pressure overload: a longitudinal in vivo PET, MRI, and MRS study on cardiac metabolic, structural, and functional adaptations.

PubMed

Abdurrachim, Desiree; Nabben, Miranda; Hoerr, Verena; Kuhlmann, Michael T; Bovenkamp, Philipp; Ciapaite, Jolita; Geraets, Ilvy M E; Coumans, Will; Luiken, Joost J F P; Glatz, Jan F C; Schäfers, Michael; Nicolay, Klaas; Faber, Cornelius; Hermann, Sven; Prompers, Jeanine J

2017-08-01

Heart failure is associated with altered myocardial substrate metabolism and impaired cardiac energetics. Comorbidities like diabetes may influence the metabolic adaptations during heart failure development. We quantified to what extent changes in substrate preference, lipid accumulation, and energy status predict the longitudinal development of hypertrophy and failure in the non-diabetic and the diabetic heart. Transverse aortic constriction (TAC) was performed in non-diabetic (db/+) and diabetic (db/db) mice to induce pressure overload. Magnetic resonance imaging, 31P magnetic resonance spectroscopy (MRS), 1H MRS, and 18F-fluorodeoxyglucose-positron emission tomography (PET) were applied to measure cardiac function, energy status, lipid content, and glucose uptake, respectively. In vivo measurements were complemented with ex vivo techniques of high-resolution respirometry, proteomics, and western blotting to elucidate the underlying molecular pathways. In non-diabetic mice, TAC induced progressive cardiac hypertrophy and dysfunction, which correlated with increased protein kinase D-1 (PKD1) phosphorylation and increased glucose uptake. These changes in glucose utilization preceded a reduction in cardiac energy status. At baseline, compared with non-diabetic mice, diabetic mice showed normal cardiac function, higher lipid content and mitochondrial capacity for fatty acid oxidation, and lower PKD1 phosphorylation, glucose uptake, and energetics. Interestingly, TAC affected cardiac function only mildly in diabetic mice, which was accompanied by normalization of phosphorylated PKD1, glucose uptake, and cardiac energy status. The cardiac metabolic adaptations in diabetic mice seem to prevent the heart from failing upon pressure overload, suggesting that restoring the balance between glucose and fatty acid utilization is beneficial for cardiac function. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions please email: journals.permissions@oup.com.

Ovine cardiac Na,K-ATPase: isolation by means of selective solubilization in Lubrol and the effect of 1 alpha,2 alpha-epoxyscillirosidin on this enzyme.

PubMed

Venter, P A; Naudé, R J; Oelofsen, W; Swan, G E

1997-01-01

The inhibition of cardiac Na,K-ATPase by 1 alpha,2 alpha-epoxyscillirosidin is the principal cause of poisoning of cattle by the tulip, Homeria pallida. The ultimate goals of this study were to study the interaction between 1 alpha,2 alpha-epoxyscillirosidin and ovine Na,K-ATPase by means of inhibition and displacement binding studies. Ovine cardiac Na,K-ATPase was isolated in membrane-bound form by means of deoxycholate treatment, high-speed ultracentrifugation, NaI treatment and selective solubilization in Lubrol. The inhibition of ovine cardiac and commercial porcine cerebral cortex Na,K-ATPase by 1 alpha,2 alpha-epoxyscilirosidin and ouabain was studied using a discontinuous Na,K-ATPase assay. The binding of 1 alpha,2 alpha-epoxyscillirosidin, ouabain and digoxin to the above enzymes was compared using a displacement binding assay with [3H] oubain. The Lubrol-solubilized ovine cardiac Na,K-ATPase showed a specific activity of 0.3 U/mg with no ouabain insensitive activity. I50 values of 2.1 x 10(-8) and 2.7 x 10(-8) were obtained for the inhibition of this enzyme by 1 alpha,2 alpha-epoxyscillirosidin and ouabain, respectively. 1 alpha,2 alpha-Epoxyscillirosidin has a much higher KD value (1.5 x 10(-7) M), however, than ouabain (9.5 x 10(-9) M) and digoxin (1.7 x 10(-8) M) in displacement binding studies with [3H]ouabain. 1 alpha,2 alpha-Epoxyscillirosidin is a potent inhibitor of ovine cardiac Na,K-ATPase and is a slightly stronger inhibitor of the enzyme than ouabain. The anomalous result for the displacement of 1 alpha,2 alpha-epoxyscillirosidin from its receptor is either a result of different affinities that K+ has for the enzyme ouabain and enzyme-1 alpha,2 alpha-epoxyscillirosidin complexes or because of different complex stabilities of these complexes.

Recurrent myocardial infarction: Mechanisms of free-floating adaptation and autonomic derangement in networked cardiac neural control

PubMed Central

Ardell, Jeffrey L.; Shivkumar, Kalyanam; Armour, J. Andrew

2017-01-01

The cardiac nervous system continuously controls cardiac function whether or not pathology is present. While myocardial infarction typically has a major and catastrophic impact, population studies have shown that longer-term risk for recurrent myocardial infarction and the related potential for sudden cardiac death depends mainly upon standard atherosclerotic variables and autonomic nervous system maladaptations. Investigative neurocardiology has demonstrated that autonomic control of cardiac function includes local circuit neurons for networked control within the peripheral nervous system. The structural and adaptive characteristics of such networked interactions define the dynamics and a new normal for cardiac control that results in the aftermath of recurrent myocardial infarction and/or unstable angina that may or may not precipitate autonomic derangement. These features are explored here via a mathematical model of cardiac regulation. A main observation is that the control environment during pathology is an extrapolation to a setting outside prior experience. Although global bounds guarantee stability, the resulting closed-loop dynamics exhibited while the network adapts during pathology are aptly described as ‘free-floating’ in order to emphasize their dependence upon details of the network structure. The totality of the results provide a mechanistic reasoning that validates the clinical practice of reducing sympathetic efferent neuronal tone while aggressively targeting autonomic derangement in the treatment of ischemic heart disease. PMID:28692680

Galectin-1 Prevents Infection and Damage Induced by Trypanosoma cruzi on Cardiac Cells

PubMed Central

Benatar, Alejandro F.; García, Gabriela A.; Bua, Jacqeline; Cerliani, Juan P.; Postan, Miriam; Tasso, Laura M.; Scaglione, Jorge; Stupirski, Juan C.; Toscano, Marta A.

2015-01-01

Background Chronic Chagas cardiomyopathy caused by Trypanosoma cruzi is the result of a pathologic process starting during the acute phase of parasite infection. Among different factors, the specific recognition of glycan structures by glycan-binding proteins from the parasite or from the mammalian host cells may play a critical role in the evolution of the infection. Methodology and Principal Findings Here we investigated the contribution of galectin–1 (Gal–1), an endogenous glycan-binding protein abundantly expressed in human and mouse heart, to the pathophysiology of T. cruzi infection, particularly in the context of cardiac pathology. We found that exposure of HL–1 cardiac cells to Gal–1 reduced the percentage of infection by two different T. cruzi strains, Tulahuén (TcVI) and Brazil (TcI). In addition, Gal–1 prevented exposure of phosphatidylserine and early events in the apoptotic program by parasite infection on HL–1 cells. These effects were not mediated by direct interaction with the parasite surface, suggesting that Gal–1 may act through binding to host cells. Moreover, we also observed that T. cruzi infection altered the glycophenotype of cardiac cells, reducing binding of exogenous Gal–1 to the cell surface. Consistent with these data, Gal–1 deficient (Lgals1 -/-) mice showed increased parasitemia, reduced signs of inflammation in heart and skeletal muscle tissues, and lower survival rates as compared to wild-type (WT) mice in response to intraperitoneal infection with T. cruzi Tulahuén strain. Conclusion/Significance Our results indicate that Gal–1 modulates T. cruzi infection of cardiac cells, highlighting the relevance of galectins and their ligands as regulators of host-parasite interactions. PMID:26451839

Rapidly rule out acute myocardial infarction by combining copeptin and heart-type fatty acid-binding protein with cardiac troponin.

PubMed

Jacobs, Leo H J; van Borren, Marcel; Gemen, Eugenie; van Eck, Martijn; van Son, Bas; Glatz, Jan F C; Daniels, Marcel; Kusters, Ron

2015-09-01

The rapid exclusion of acute myocardial infarction in patients with chest pain can reduce the length of hospital admission, prevent unnecessary diagnostic work-up and reduce the burden on our health-care systems. The combined use of biomarkers that are associated with different pathophysiological aspects of acute myocardial infarction could improve the early diagnostic assessment of patients presenting with chest pain. We measured cardiac troponin I, copeptin and heart-type fatty acid-binding protein concentrations in 584 patients who presented to the emergency department with acute chest pain. The diagnostic performances for the diagnosis of acute myocardial infarction and NSTEMI were calculated for the individual markers and their combinations. Separate calculations were made for patients presenting to the emergency department <3 h, 3-6 h and 6-12 h after chest pain onset. For ruling out acute myocardial infarction, the net predictive values (95% CI) of cardiac troponin I, copeptin and heart-type fatty acid-binding protein were 90.4% (87.3-92.9), 84% (79.8-87.6) and 87% (83.5-90), respectively. Combining the three biomarkers resulted in a net predictive value of 95.8% (92.8-97.8). The improvement was most pronounced in the early presenters (<3 h) where the combined net predictive value was 92.9% (87.3-96.5) compared to 84.6% (79.4-88.9) for cardiac troponin I alone. The area under the receiver operating characteristic for the triple biomarker combination increased significantly (P < 0.05) compared to that of cardiac troponin I alone (0.880 [0.833-0.928] vs. 0.840 [0.781-0.898], respectively). Combining copeptin, heart-type fatty acid-binding protein and cardiac troponin I measurements improves the diagnostic performance in patients presenting with chest pain. Importantly, in patients who present early (<3 h) after chest pain onset, the combination improves the diagnostic performance compared to the standard cardiac troponin I measurement alone. © The Author(s) 2015.

Obscurin Targets Ankyrin-B and Protein Phosphatase 2A to the Cardiac M-line*

PubMed Central

Cunha, Shane R.; Mohler, Peter J.

2008-01-01

Ankyrin-B targets ion channels and transporters in excitable cells. Dysfunction in ankyrin-B-based pathways results in defects in cardiac physiology. Despite a wealth of knowledge regarding the role of ankyrin-B for cardiac function, little is known regarding the mechanisms underlying ankyrin-B regulation. Moreover, the pathways underlying ankyrin-B targeting in heart are unclear. We report that alternative splicing regulates ankyrin-B localization and function in cardiomyocytes. Specifically, we identify a novel exon (exon 43′) in the ankyrin-B regulatory domain that mediates interaction with the Rho-GEF obscurin. Ankyrin-B transcripts harboring exon 43′ represent the primary cardiac isoform in human and mouse. We demonstrate that ankyrin-B and obscurin are co-localized at the M-line of myocytes and co-immunoprecipitate from heart. We define the structural requirements for ankyrin-B/obscurin interaction to two motifs in the ankyrin-B regulatory domain and demonstrate that both are critical for obscurin/ankyrin-B interaction. In addition, we demonstrate that interaction with obscurin is required for ankyrin-B M-line targeting. Specifically, both obscurin-binding motifs are required for the M-line targeting of a GFP-ankyrin-B regulatory domain. Moreover, this construct acts as a dominant-negative by competing with endogenous ankyrin-B for obscurin-binding at the M-line, thus providing a powerful new tool to evaluate the function of obscurin/ankyrin-B interactions. With this new tool, we demonstrate that the obscurin/ankyrin-B interaction is critical for recruitment of PP2A to the cardiac M-line. Together, these data provide the first evidence for the molecular basis of ankyrin-B and PP2A targeting and function at the cardiac M-line. Finally, we report that ankyrin-B R1788W is localized adjacent to the ankyrin-B obscurin-binding motif and increases binding activity for obscurin. In summary, our new findings demonstrate that ANK2 is subject to alternative splicing that gives rise to unique polypeptides with diverse roles in cardiac function. PMID:18782775

Reducing RBM20 activity improves diastolic dysfunction and cardiac atrophy.

PubMed

Hinze, Florian; Dieterich, Christoph; Radke, Michael H; Granzier, Henk; Gotthardt, Michael

2016-12-01

Impaired diastolic filling is a main contributor to heart failure with preserved ejection fraction (HFpEF), a syndrome with increasing prevalence and no treatment. Both collagen and the giant sarcomeric protein titin determine diastolic function. Since titin's elastic properties can be adjusted physiologically, we evaluated titin-based stiffness as a therapeutic target. We adjusted RBM20-dependent cardiac isoform expression in the titin N2B knockout mouse with increased ventricular stiffness. A ~50 % reduction of RBM20 activity does not only maintain cardiac filling in diastole but also ameliorates cardiac atrophy and thus improves cardiac function in the N2B-deficient heart. Reduced RBM20 activity partially normalized gene expression related to muscle development and fatty acid metabolism. The adaptation of cardiac growth was related to hypertrophy signaling via four-and-a-half lim-domain proteins (FHLs) that translate mechanical input into hypertrophy signals. We provide a novel link between cardiac isoform expression and trophic signaling via FHLs and suggest cardiac splicing as a therapeutic target in diastolic dysfunction. Increasing the length of titin isoforms improves ventricular filling in heart disease. FHL proteins are regulated via RBM20 and adapt cardiac growth. RBM20 is a therapeutic target in diastolic dysfunction.

BET Acetyl-Lysine Binding Proteins Control Pathological Cardiac Hypertrophy

PubMed Central

Spiltoir, Jessica I.; Stratton, Matthew S.; Cavasin, Maria A.; Demos-Davies, Kim; Reid, Brian G.; Qi, Jun; Bradner, James E.; McKinsey, Timothy A.

2014-01-01

Cardiac hypertrophy is an independent predictor of adverse outcomes in patients with heart failure, and thus represents an attractive target for novel therapeutic intervention. JQ1, a small molecule inhibitor of bromodomain and extraterminal (BET) acetyl-lysine reader proteins, was identified in a high throughput screen designed to discover novel small molecule regulators of cardiomyocyte hypertrophy. JQ1 dose-dependently blocked agonist-dependent hypertrophy of cultured neonatal rat ventricular myocytes (NRVMs) and reversed the prototypical gene program associated with pathological cardiac hypertrophy. JQ1 also blocked left ventricular hypertrophy (LVH) and improved cardiac function in adult mice subjected to transverse aortic constriction (TAC). The BET family consists of BRD2, BRD3, BRD4 and BRDT. BRD4 protein expression was increased during cardiac hypertrophy, and hypertrophic stimuli promoted recruitment of BRD4 to the transcriptional start site (TSS) of the gene encoding atrial natriuretic factor (ANF). Binding of BRD4 to the ANF TSS was associated with increased phosphorylation of local RNA polymerase II. These findings define a novel function for BET proteins as signal-responsive regulators of cardiac hypertrophy, and suggest that small molecule inhibitors of these epigenetic reader proteins have potential as therapeutics for heart failure. PMID:23939492

Adaptive servo ventilation improves cardiac dysfunction and prognosis in chronic heart failure patients with Cheyne-Stokes respiration.

PubMed

Yoshihisa, Akiomi; Shimizu, Takeshi; Owada, Takashi; Nakamura, Yuichi; Iwaya, Shoji; Yamauchi, Hiroyuki; Miyata, Makiko; Hoshino, Yasuto; Sato, Takamasa; Suzuki, Satoshi; Sugimoto, Koichi; Yamaki, Takayoshi; Kunii, Hiroyuki; Nakazato, Kazuhiko; Suzuki, Hitoshi; Saitoh, Shu-ichi; Takeishi, Yasuchika

2011-01-01

Cheyne-Stokes respiration (CSR) is often observed in patients with chronic heart failure (CHF). Although adaptive servo ventilation (ASV) is effective for CSR, it remains unclear whether ASV improves the cardiac function and prognosis of patients with CHF and CSR.Sixty patients with CHF and CSR (mean left ventricular ejection fraction 38.7%, mean apnea hypopnea index 36.8 times/hour, mean central apnea index 19.1 times/hour) were enrolled in this study. Patients were divided into two groups: 23 patients treated with ASV (ASV group) and 37 patients treated without ASV (Non-ASV group). Measurement of plasma B-type natriuretic peptide (BNP) levels and echocardiography were performed before, 3 and 6 months after treatments in each group. Patients were followed-up for cardiac events (cardiac death and re-hospitalization) after discharge. In the ASV group, NYHA functional class, BNP levels, cardiac systolic and diastolic function were significantly improved with ASV treatment for 6 months. In contrast, none of these parameters changed in the Non-ASV group. Importantly, Kaplan-Meier analysis clearly demonstrated that the event-free rate was significantly higher in the ASV group than in the Non-ASV group.Adaptive servo ventilation improves cardiac function and prognosis in patients with chronic heart failure and Cheyne-Stokes respiration.

Loss of Notch3 Signaling in Vascular Smooth Muscle Cells Promotes Severe Heart Failure Upon Hypertension.

PubMed

Ragot, Hélène; Monfort, Astrid; Baudet, Mathilde; Azibani, Fériel; Fazal, Loubina; Merval, Régine; Polidano, Evelyne; Cohen-Solal, Alain; Delcayre, Claude; Vodovar, Nicolas; Chatziantoniou, Christos; Samuel, Jane-Lise

2016-08-01

Hypertension, which is a risk factor of heart failure, provokes adaptive changes at the vasculature and cardiac levels. Notch3 signaling plays an important role in resistance arteries by controlling the maturation of vascular smooth muscle cells. Notch3 deletion is protective in pulmonary hypertension while deleterious in arterial hypertension. Although this latter phenotype was attributed to renal and cardiac alterations, the underlying mechanisms remained unknown. To investigate the role of Notch3 signaling in the cardiac adaptation to hypertension, we used mice with either constitutive Notch3 or smooth muscle cell-specific conditional RBPJκ knockout. At baseline, both genotypes exhibited a cardiac arteriolar rarefaction associated with oxidative stress. In response to angiotensin II-induced hypertension, the heart of Notch3 knockout and SM-RBPJκ knockout mice did not adapt to pressure overload and developed heart failure, which could lead to an early and fatal acute decompensation of heart failure. This cardiac maladaptation was characterized by an absence of media hypertrophy of the media arteries, the transition of smooth muscle cells toward a synthetic phenotype, and an alteration of angiogenic pathways. A subset of mice exhibited an early fatal acute decompensated heart failure, in which the same alterations were observed, although in a more rapid timeframe. Altogether, these observations indicate that Notch3 plays a major role in coronary adaptation to pressure overload. These data also show that the hypertrophy of coronary arterial media on pressure overload is mandatory to initially maintain a normal cardiac function and is regulated by the Notch3/RBPJκ pathway. © 2016 American Heart Association, Inc.

Molecular Mechanisms Underlying Cardiac Adaptation to Exercise

PubMed Central

Vega, Rick B.; Konhilas, John P.; Kelly, Daniel P.; Leinwand, Leslie A.

2017-01-01

Exercise elicits coordinated multi-organ responses including skeletal muscle, vasculature, heart and lung. In the short term, the output of the heart increases to meet the demand of strenuous exercise. Long term exercise instigates remodeling of the heart including growth and adaptive molecular and cellular re-programming. Signaling pathways such as the insulin-like growth factor 1/PI3K/Akt pathway mediate many of these responses. Exercise-induced, or physiologic, cardiac growth contrasts with growth elicited by pathological stimuli such as hypertension. Comparing the molecular and cellular underpinnings of physiologic and pathologic cardiac growth has unveiled phenotype-specific signaling pathways and transcriptional regulatory programs. Studies suggest that exercise pathways likely antagonize pathological pathways, and exercise training is often recommended for patients with chronic stable heart failure or following myocardial infarction. Herein, we summarize the current understanding of the structural and functional cardiac responses to exercise as well as signaling pathways and downstream effector molecules responsible for these adaptations. PMID:28467921

Evaluation of an adaptive detector collimation for prospectively ECG-triggered coronary CT angiography with third-generation dual-source CT.

PubMed

Messerli, Michael; Dewes, Patricia; Scholtz, Jan-Erik; Arendt, Christophe; Wildermuth, Simon; Vogl, Thomas J; Bauer, Ralf W

2018-05-01

To investigate the impact of an adaptive detector collimation on the dose parameters and accurateness of scan length adaption at prospectively ECG-triggered sequential cardiac CT with a wide-detector third-generation dual-source CT. Ideal scan lengths for human hearts were retrospectively derived from 103 triple-rule-out examinations. These measures were entered into the new scanner operated in prospectively ECG-triggered sequential cardiac scan mode with three different detector settings: (1) adaptive collimation, (2) fixed 64 × 0.6-mm collimation, and (3) fixed 96 × 0.6-mm collimation. Differences in effective scan length and deviation from the ideal scan length and dose parameters (CTDIvol, DLP) were documented. The ideal cardiac scan length could be matched by the adaptive collimation in every case while the mean scanned length was longer by 15.4% with the 64 × 0.6 mm and by 27.2% with the fixed 96 × 0.6-mm collimation. While the DLP was almost identical between the adaptive and the 64 × 0.6-mm collimation (83 vs. 89 mGycm at 120 kV), it was 62.7% higher with the 96 × 0.6-mm collimation (135 mGycm), p < 0.001. The adaptive detector collimation for prospectively ECG-triggered sequential acquisition allows for adjusting the scan length as accurate as this can only be achieved with a spiral acquisition. This technique allows keeping patient exposure low where patient dose would significantly increase with the traditional step-and-shoot mode. • Adaptive detector collimation allows keeping patient exposure low in cardiac CT. • With novel detectors the desired scan length can be accurately matched. • Differences in detector settings may cause 62.7% of excessive dose.

Diet and sex modify exercise and cardiac adaptation in the mouse

PubMed Central

Chen, Hao; Luczak, Elizabeth; McKee, Laurel A.; Regan, Jessica; Watson, Peter A.; Stauffer, Brian L.; Khalpey, Zain I; Mckinsey, Timothy A.; Horn, Todd; LaFleur, Bonnie; Leinwand, Leslie A.

2014-01-01

The heart adapts to exercise stimuli in a sex-dimorphic manner when mice are fed the traditional soy-based chow. Females undergo more voluntary exercise (4 wk) than males and exhibit more cardiac hypertrophy per kilometer run (18, 32). We have found that diet plays a critical role in cage wheel exercise and cardiac adaptation to the exercise stimulus in this sex dimorphism. Specifically, feeding male mice a casein-based, soy-free diet increases daily running distance over soy-fed counterparts to equal that of females. Moreover, casein-fed males have a greater capacity to increase their cardiac mass in response to exercise compared with soy-fed males. To further explore the biochemical mechanisms for these differences, we performed a candidate-based RT-PCR screen on genes previously implicated in diet- or exercise-based cardiac hypertrophy. Of the genes screened, many exhibit significant exercise, diet, or sex effects but only transforming growth factor-β1 shows a significant three-way interaction with no genes showing a two-way interaction. Finally, we show that the expression and activity of adenosine monophosphate-activated kinase-α2 and acetyl-CoA carboxylase is dependent on exercise, diet, and sex. PMID:25398983

Diet and sex modify exercise and cardiac adaptation in the mouse.

PubMed

Konhilas, John P; Chen, Hao; Luczak, Elizabeth; McKee, Laurel A; Regan, Jessica; Watson, Peter A; Stauffer, Brian L; Khalpey, Zain I; Mckinsey, Timothy A; Horn, Todd; LaFleur, Bonnie; Leinwand, Leslie A

2015-01-15

The heart adapts to exercise stimuli in a sex-dimorphic manner when mice are fed the traditional soy-based chow. Females undergo more voluntary exercise (4 wk) than males and exhibit more cardiac hypertrophy per kilometer run (18, 32). We have found that diet plays a critical role in cage wheel exercise and cardiac adaptation to the exercise stimulus in this sex dimorphism. Specifically, feeding male mice a casein-based, soy-free diet increases daily running distance over soy-fed counterparts to equal that of females. Moreover, casein-fed males have a greater capacity to increase their cardiac mass in response to exercise compared with soy-fed males. To further explore the biochemical mechanisms for these differences, we performed a candidate-based RT-PCR screen on genes previously implicated in diet- or exercise-based cardiac hypertrophy. Of the genes screened, many exhibit significant exercise, diet, or sex effects but only transforming growth factor-β1 shows a significant three-way interaction with no genes showing a two-way interaction. Finally, we show that the expression and activity of adenosine monophosphate-activated kinase-α2 and acetyl-CoA carboxylase is dependent on exercise, diet, and sex.

Cardiac-specific overexpression of aldehyde dehydrogenase 2 exacerbates cardiac remodeling in response to pressure overload.

PubMed

Dassanayaka, Sujith; Zheng, Yuting; Gibb, Andrew A; Cummins, Timothy D; McNally, Lindsey A; Brittian, Kenneth R; Jagatheesan, Ganapathy; Audam, Timothy N; Long, Bethany W; Brainard, Robert E; Jones, Steven P; Hill, Bradford G

2018-06-01

Pathological cardiac remodeling during heart failure is associated with higher levels of lipid peroxidation products and lower abundance of several aldehyde detoxification enzymes, including aldehyde dehydrogenase 2 (ALDH2). An emerging idea that could explain these findings concerns the role of electrophilic species in redox signaling, which may be important for adaptive responses to stress or injury. The purpose of this study was to determine whether genetically increasing ALDH2 activity affects pressure overload-induced cardiac dysfunction. Mice subjected to transverse aortic constriction (TAC) for 12 weeks developed myocardial hypertrophy and cardiac dysfunction, which were associated with diminished ALDH2 expression and activity. Cardiac-specific expression of the human ALDH2 gene in mice augmented myocardial ALDH2 activity but did not improve cardiac function in response to pressure overload. After 12 weeks of TAC, ALDH2 transgenic mice had larger hearts than their wild-type littermates and lower capillary density. These findings show that overexpression of ALDH2 augments the hypertrophic response to pressure overload and imply that downregulation of ALDH2 may be an adaptive response to certain forms of cardiac pathology. Copyright © 2018. Published by Elsevier B.V.

Forskolin- and dihydroalprenolol (DHA) binding sites and adenylate cyclase activity in heart of rats fed diets containing different oils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alam, S.Q.; Ren, Y.F.; Alam, B.S.

1987-05-01

The purpose of the present investigation was to determine if dietary lipids can induce changes in the adenylate cyclase system in rat heart. Three groups of male young Sprague-Dawley rats were fed for 6 weeks diets containing 10% corn oil (I), 8% coconut oil + 2% corn oil (II) or 10% menhaden oil (III). Adenylate cyclase activity (basal, fluoride-, isoproterenol-, and forskolin-stimulated) was higher in heart homogenates of rats in group III than in the other two groups. Concentration of the (/sup 3/H)-forskolin binding sites in the cardiac membranes were significantly higher in rats fed menhaden oil. The values (pmol/mgmore » protein) were 4.8 +/- 0.2 (I), 4.5 +/- 0.7 (II) and 8.4 +/- 0.5 (III). There was no significant difference in the affinity of the forskolin binding sites among the 3 dietary groups. When measured at different concentrations of forskolin, the adenylate cyclase activity in cardiac membranes of rats fed menhaden oil was higher than in the other 2 groups. Concentrations of the (/sup 3/H)DHA binding sites were slightly higher but their affinity was lower in cardiac membranes of rats fed menhaden oil. The results suggest that diets containing fish oil increase the concentration of the forskolin binding sites and may also affect the characteristics of the ..beta..-adrenergic receptor in rat heart.« less

Small heterodimer partner blocks cardiac hypertrophy by interfering with GATA6 signaling.

PubMed

Nam, Yoon Seok; Kim, Yoojung; Joung, Hosouk; Kwon, Duk-Hwa; Choe, Nakwon; Min, Hyun-Ki; Kim, Yong Sook; Kim, Hyung-Seok; Kim, Don-Kyu; Cho, Young Kuk; Kim, Yong-Hoon; Nam, Kwang-Il; Choi, Hyoung Chul; Park, Dong Ho; Suk, Kyoungho; Lee, In-Kyu; Ahn, Youngkeun; Lee, Chul-Ho; Choi, Hueng-Sik; Eom, Gwang Hyeon; Kook, Hyun

2014-08-15

Small heterodimer partner (SHP; NR0B2) is an atypical orphan nuclear receptor that lacks a conventional DNA-binding domain. Through interactions with other transcription factors, SHP regulates diverse biological events, including glucose metabolism in liver. However, the role of SHP in adult heart diseases has not yet been demonstrated. We aimed to investigate the role of SHP in adult heart in association with cardiac hypertrophy. The roles of SHP in cardiac hypertrophy were tested in primary cultured cardiomyocytes and in animal models. SHP-null mice showed a hypertrophic phenotype. Hypertrophic stresses repressed the expression of SHP, whereas forced expression of SHP blocked the development of hypertrophy in cardiomyocytes. SHP reduced the protein amount of Gata6 and, by direct physical interaction with Gata6, interfered with the binding of Gata6 to GATA-binding elements in the promoter regions of natriuretic peptide precursor type A. Metformin, an antidiabetic agent, induced SHP and suppressed cardiac hypertrophy. The metformin-induced antihypertrophic effect was attenuated either by SHP small interfering RNA in cardiomyocytes or in SHP-null mice. These results establish SHP as a novel antihypertrophic regulator that acts by interfering with GATA6 signaling. SHP may participate in the metformin-induced antihypertrophic response. © 2014 American Heart Association, Inc.

Selection of DNA aptamers against Human Cardiac Troponin I for colorimetric sensor based dot blot application.

PubMed

Dorraj, Ghamar Soltan; Rassaee, Mohammad Javad; Latifi, Ali Mohammad; Pishgoo, Bahram; Tavallaei, Mahmood

2015-08-20

Troponin T and I are ideal markers which are highly sensitive and specific for myocardial injury and have shown better efficacy than earlier markers. Since aptamers are ssDNA or RNA that bind to a wide variety of target molecules, the purpose of this research was to select an aptamer from a 79bp single-stranded DNA (ssDNA) random library that was used to bind the Human Cardiac Troponin I from a synthetic nucleic acids library by systematic evolution of ligands exponential enrichment (Selex) based on several selection and amplification steps. Human Cardiac Troponin I protein was coated onto the surface of streptavidin magnetic beads to extract specific aptamer from a large and diverse random ssDNA initial oligonucleotide library. As a result, several aptamers were selected and further examined for binding affinity and specificity. Finally TnIApt 23 showed beast affinity in nanomolar range (2.69nM) toward the target protein. A simple and rapid colorimetric detection assay for Human Cardiac Troponin I using the novel and specific aptamer-AuNPs conjugates based on dot blot assay was developed. The detection limit for this protein using aptamer-AuNPs-based assay was found to be 5ng/ml. Copyright © 2015 Elsevier B.V. All rights reserved.

The ESCRT-III pathway facilitates cardiomyocyte release of cBIN1-containing microparticles

PubMed Central

Xu, Bing; Fu, Ying; Liu, Yan; Agvanian, Sosse; Wirka, Robert C.; Baum, Rachel; Zhou, Kang; Shaw, Robin M.

2017-01-01

Microparticles (MPs) are cell–cell communication vesicles derived from the cell surface plasma membrane, although they are not known to originate from cardiac ventricular muscle. In ventricular cardiomyocytes, the membrane deformation protein cardiac bridging integrator 1 (cBIN1 or BIN1+13+17) creates transverse-tubule (t-tubule) membrane microfolds, which facilitate ion channel trafficking and modulate local ionic concentrations. The microfold-generated microdomains continuously reorganize, adapting in response to stress to modulate the calcium signaling apparatus. We explored the possibility that cBIN1-microfolds are externally released from cardiomyocytes. Using electron microscopy imaging with immunogold labeling, we found in mouse plasma that cBIN1 exists in membrane vesicles about 200 nm in size, which is consistent with the size of MPs. In mice with cardiac-specific heterozygous Bin1 deletion, flow cytometry identified 47% less cBIN1-MPs in plasma, supporting cardiac origin. Cardiac release was also evidenced by the detection of cBIN1-MPs in medium bathing a pure population of isolated adult mouse cardiomyocytes. In human plasma, osmotic shock increased cBIN1 detection by enzyme-linked immunosorbent assay (ELISA), and cBIN1 level decreased in humans with heart failure, a condition with reduced cardiac muscle cBIN1, both of which support cBIN1 release in MPs from human hearts. Exploring putative mechanisms of MP release, we found that the membrane fission complex endosomal sorting complexes required for transport (ESCRT)-III subunit charged multivesicular body protein 4B (CHMP4B) colocalizes and coimmunoprecipitates with cBIN1, an interaction enhanced by actin stabilization. In HeLa cells with cBIN1 overexpression, knockdown of CHMP4B reduced the release of cBIN1-MPs. Using truncation mutants, we identified that the N-terminal BAR (N-BAR) domain in cBIN1 is required for CHMP4B binding and MP release. This study links the BAR protein superfamily to the ESCRT pathway for MP biogenesis in mammalian cardiac ventricular cells, identifying elements of a pathway by which cytoplasmic cBIN1 is released into blood. PMID:28806752

The ESCRT-III pathway facilitates cardiomyocyte release of cBIN1-containing microparticles.

PubMed

Xu, Bing; Fu, Ying; Liu, Yan; Agvanian, Sosse; Wirka, Robert C; Baum, Rachel; Zhou, Kang; Shaw, Robin M; Hong, TingTing

2017-08-01

Microparticles (MPs) are cell-cell communication vesicles derived from the cell surface plasma membrane, although they are not known to originate from cardiac ventricular muscle. In ventricular cardiomyocytes, the membrane deformation protein cardiac bridging integrator 1 (cBIN1 or BIN1+13+17) creates transverse-tubule (t-tubule) membrane microfolds, which facilitate ion channel trafficking and modulate local ionic concentrations. The microfold-generated microdomains continuously reorganize, adapting in response to stress to modulate the calcium signaling apparatus. We explored the possibility that cBIN1-microfolds are externally released from cardiomyocytes. Using electron microscopy imaging with immunogold labeling, we found in mouse plasma that cBIN1 exists in membrane vesicles about 200 nm in size, which is consistent with the size of MPs. In mice with cardiac-specific heterozygous Bin1 deletion, flow cytometry identified 47% less cBIN1-MPs in plasma, supporting cardiac origin. Cardiac release was also evidenced by the detection of cBIN1-MPs in medium bathing a pure population of isolated adult mouse cardiomyocytes. In human plasma, osmotic shock increased cBIN1 detection by enzyme-linked immunosorbent assay (ELISA), and cBIN1 level decreased in humans with heart failure, a condition with reduced cardiac muscle cBIN1, both of which support cBIN1 release in MPs from human hearts. Exploring putative mechanisms of MP release, we found that the membrane fission complex endosomal sorting complexes required for transport (ESCRT)-III subunit charged multivesicular body protein 4B (CHMP4B) colocalizes and coimmunoprecipitates with cBIN1, an interaction enhanced by actin stabilization. In HeLa cells with cBIN1 overexpression, knockdown of CHMP4B reduced the release of cBIN1-MPs. Using truncation mutants, we identified that the N-terminal BAR (N-BAR) domain in cBIN1 is required for CHMP4B binding and MP release. This study links the BAR protein superfamily to the ESCRT pathway for MP biogenesis in mammalian cardiac ventricular cells, identifying elements of a pathway by which cytoplasmic cBIN1 is released into blood.

Sarcospan Regulates Cardiac Isoproterenol Response and Prevents Duchenne Muscular Dystrophy-Associated Cardiomyopathy.

PubMed

Parvatiyar, Michelle S; Marshall, Jamie L; Nguyen, Reginald T; Jordan, Maria C; Richardson, Vanitra A; Roos, Kenneth P; Crosbie-Watson, Rachelle H

2015-12-23

Duchenne muscular dystrophy is a fatal cardiac and skeletal muscle disease resulting from mutations in the dystrophin gene. We have previously demonstrated that a dystrophin-associated protein, sarcospan (SSPN), ameliorated Duchenne muscular dystrophy skeletal muscle degeneration by activating compensatory pathways that regulate muscle cell adhesion (laminin-binding) to the extracellular matrix. Conversely, loss of SSPN destabilized skeletal muscle adhesion, hampered muscle regeneration, and reduced force properties. Given the importance of SSPN to skeletal muscle, we investigated the consequences of SSPN ablation in cardiac muscle and determined whether overexpression of SSPN into mdx mice ameliorates cardiac disease symptoms associated with Duchenne muscular dystrophy cardiomyopathy. SSPN-null mice exhibited cardiac enlargement, exacerbated cardiomyocyte hypertrophy, and increased fibrosis in response to β-adrenergic challenge (isoproterenol; 0.8 mg/day per 2 weeks). Biochemical analysis of SSPN-null cardiac muscle revealed reduced sarcolemma localization of many proteins with a known role in cardiomyopathy pathogenesis: dystrophin, the sarcoglycans (α-, δ-, and γ-subunits), and β1D integrin. Transgenic overexpression of SSPN in Duchenne muscular dystrophy mice (mdx(TG)) improved cardiomyofiber cell adhesion, sarcolemma integrity, cardiac functional parameters, as well as increased expression of compensatory transmembrane proteins that mediate attachment to the extracellular matrix. SSPN regulates sarcolemmal expression of laminin-binding complexes that are critical to cardiac muscle function and protects against transient and chronic injury, including inherited cardiomyopathy. © 2015 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

Pediatric Out-of-Hospital Cardiac Arrest Characteristics and Their Association With Survival and Neurobehavioral Outcome.

PubMed

Meert, Kathleen L; Telford, Russell; Holubkov, Richard; Slomine, Beth S; Christensen, James R; Dean, J Michael; Moler, Frank W

2016-12-01

To investigate relationships between cardiac arrest characteristics and survival and neurobehavioral outcome among children recruited to the Therapeutic Hypothermia after Pediatric Cardiac Arrest Out-of-Hospital trial. Secondary analysis of Therapeutic Hypothermia after Pediatric Cardiac Arrest Out-of-Hospital trial data. Thirty-six PICUs in the United States and Canada. All children (n = 295) had chest compressions for greater than or equal to 2 minutes, were comatose, and required mechanical ventilation after return of circulation. Neurobehavioral function was assessed using the Vineland Adaptive Behavior Scales, Second Edition at baseline (reflecting prearrest status) and 12 months postarrest. U.S. norms for Vineland Adaptive Behavior Scales, Second Edition scores are 100 (mean) ± 15 (SD). Higher scores indicate better functioning. Outcomes included 12-month survival and 12-month survival with Vineland Adaptive Behavior Scales, Second Edition greater than or equal to 70. Cardiac etiology of arrest, initial arrest rhythm of ventricular fibrillation/tachycardia, shorter duration of chest compressions, compressions not required at hospital arrival, fewer epinephrine doses, and witnessed arrest were associated with greater 12-month survival and 12-month survival with Vineland Adaptive Behavior Scales, Second Edition greater than or equal to 70. Weekend arrest was associated with lower 12-month survival. Body habitus was associated with 12-month survival with Vineland Adaptive Behavior Scales, Second Edition greater than or equal to 70; underweight children had better outcomes, and obese children had worse outcomes. On multivariate analysis, acute life threatening event/sudden unexpected infant death, chest compressions more than 30 minutes, and weekend arrest were associated with lower 12-month survival; witnessed arrest was associated with greater 12-month survival. Acute life threatening event/sudden unexpected infant death, other respiratory causes of arrest except drowning, other/unknown causes of arrest, and compressions more than 30 minutes were associated with lower 12-month survival with Vineland Adaptive Behavior Scales, Second Edition greater than or equal to 70. Many factors are associated with survival and neurobehavioral outcome among children who are comatose and require mechanical ventilation after out-of-hospital cardiac arrest. These factors may be useful for identifying children at risk for poor outcomes, and for improving prevention and resuscitation strategies.

Analysis of steps adapted protocol in cardiac rehabilitation in the hospital phase

PubMed Central

Winkelmann, Eliane Roseli; Dallazen, Fernanda; Bronzatti, Angela Beerbaum Steinke; Lorenzoni, Juliara Cristina Werner; Windmöller, Pollyana

2015-01-01

Objective To analyze a cardiac rehabilitation adapted protocol in physical therapy during the postoperative hospital phase of cardiac surgery in a service of high complexity, in aspects regarded to complications and mortality prevalence and hospitalization days. Methods This is an observational cross-sectional, retrospective and analytical study performed by investigating 99 patients who underwent cardiac surgery for coronary artery bypass graft, heart valve replacement or a combination of both. Step program adapted for rehabilitation after cardiac surgery was analyzed under the command of the physiotherapy professional team. Results In average, a patient stays for two days in the Intensive Care Unit and three to four days in the hospital room, totalizing six days of hospitalization. Fatalities occurred in a higher percentage during hospitalization (5.1%) and up to two years period (8.6%) when compared to 30 days after hospital discharge (1.1%). Among the postoperative complications, the hemodynamic (63.4%) and respiratory (42.6%) were the most prevalent. 36-42% of complications occurred between the immediate postoperative period and the second postoperative day. The hospital discharge started from the fifth postoperative day. We can observe that in each following day, the patients are evolving in achieving the Steps, where Step 3 was the most used during the rehabilitation phase I. Conclusion This evolution program by steps can to guide the physical rehabilitation at the hospital in patients after cardiac surgery. PMID:25859866

Analysis of steps adapted protocol in cardiac rehabilitation in the hospital phase.

PubMed

Winkelmann, Eliane Roseli; Dallazen, Fernanda; Bronzatti, Angela Beerbaum Steinke; Lorenzoni, Juliara Cristina Werner; Windmöller, Pollyana

2015-01-01

To analyze a cardiac rehabilitation adapted protocol in physical therapy during the postoperative hospital phase of cardiac surgery in a service of high complexity, in aspects regarded to complications and mortality prevalence and hospitalization days. This is an observational cross-sectional, retrospective and analytical study performed by investigating 99 patients who underwent cardiac surgery for coronary artery bypass graft, heart valve replacement or a combination of both. Step program adapted for rehabilitation after cardiac surgery was analyzed under the command of the physiotherapy professional team. In average, a patient stays for two days in the Intensive Care Unit and three to four days in the hospital room, totalizing six days of hospitalization. Fatalities occurred in a higher percentage during hospitalization (5.1%) and up to two years period (8.6%) when compared to 30 days after hospital discharge (1.1%). Among the postoperative complications, the hemodynamic (63.4%) and respiratory (42.6%) were the most prevalent. 36-42% of complications occurred between the immediate postoperative period and the second postoperative day. The hospital discharge started from the fifth postoperative day. We can observe that in each following day, the patients are evolving in achieving the Steps, where Step 3 was the most used during the rehabilitation phase I. This evolution program by steps can to guide the physical rehabilitation at the hospital in patients after cardiac surgery.

Cardiac considerations in the triathlete.

PubMed

Douglas, P S

1989-10-01

The cardiac adaptation to exercise training produces a variety of adaptations in cardiac size, shape, and function. To further define these changes and to investigate the effects of maximal conditioning, we studied ultraendurance triathletes training for the Hawaii Ironman Triathlon using echocardiography, Doppler ultrasound, and electrocardiography. In this population, the left ventricle (LV) was of normal size but had increased wall thickness and mass. Systolic function was normal and diastolic function was normal or supernormal (increased ratio of rapid to atrial LV filling velocities). The finding of a pattern of concentric hypertrophy was reinforced by a close relationship between submaximal exercise systolic blood pressure and LV mass (r = 0.88). Examination of valvular function by Doppler ultrasound revealed significantly increased prevalences of mitral and tricuspid regurgitation in athletes, with 91% of athletes (vs 38% of controls) having regurgitation detected in at least one cardiac valve. Analysis of athletes using standard electrocardiographic criteria for the detection of left ventricular hypertrophy showed that these criteria did not reliably detect increased mass. However, changes such as marked QRS prolongation and nonvoltage criteria for LV hypertrophy and RV hypertrophy may be useful in separating physiologic from pathologic hypertrophy. Our studies provide additional descriptions of cardiac changes produced by ultraendurance exercise training and suggest that the hemodynamic load imposed by exercise may be a contributing cause to physiologic hypertrophy. Much yet remains to be learned about the cardiac adaptation to exercise training.

Myofibril growth during cardiac hypertrophy is regulated through dual phosphorylation and acetylation of the actin capping protein CapZ

PubMed Central

Lin, Ying-Hsi; Warren, Chad M.; Li, Jieli; McKinsey, Timothy A.; Russell, Brenda

2016-01-01

The mechanotransduction signaling pathways initiated in heart muscle by increased mechanical loading are known to lead to long-term transcriptional changes and hypertrophy, but the rapid events for adaptation at the sarcomeric level are not fully understood. The goal of this study was to test the hypothesis that actin filament assembly during cardiomyocyte growth is regulated by post-translational modifications (PTMs) of CapZβ1. In rapidly hypertrophying neonatal rat ventricular myocytes (NRVMs) stimulated by phenylephrine (PE), two-dimensional gel electrophoresis (2DGE) of CapZβ1 revealed a shift toward more negative charge. Consistent with this, mass spectrometry identified CapZβ1 phosphorylation on serine-204 and acetylation on lysine-199, two residues which are near the actin binding surface of CapZβ1. Ectopic expression of dominant negative PKCε (dnPKCε) in NRVMs blunted the PE-induced increase in CapZ dynamics, as evidenced by the kinetic constant (Kfrap) of fluorescence recovery after photobleaching (FRAP), and concomitantly reduced phosphorylation and acetylation of CapZβ1. Furthermore, inhibition of class I histone deacetylases (HDACs) increased lysine-199 acetylation on CapZβ1, which increased Kfrap of CapZ and stimulated actin dynamics. Finally, we show that PE treatment of NRVMs results in decreased binding of HDAC3 to myofibrils, suggesting a signal-dependent mechanism for the regulation of sarcomere-associated CapZβ1 acetylation. Taken together, this dual regulation through phosphorylation and acetylation of CapZβ1 provides a novel model for the regulation of myofibril growth during cardiac hypertrophy. PMID:27185186

Selectivity verification of cardiac troponin monoclonal antibodies for cardiac troponin detection by using conventional ELISA

NASA Astrophysics Data System (ADS)

Fathil, M. F. M.; Arshad, M. K. Md; Gopinath, Subash C. B.; Adzhri, R.; Ruslinda, A. R.; Hashim, U.

2017-03-01

This paper presents preparation and characterization of conventional enzyme-linked immunosorbent assay (ELISA) for cardiac troponin detection to determine the selectivity of the cardiac troponin monoclonal antibodies. Monoclonal antibodies, used to capture and bind the targets in this experiment, are cTnI monoclonal antibody (MAb-cTnI) and cTnT monoclonal antibody (MAb-cTnT), while both cardiac troponin I (cTnI) and T (cTnT) are used as targets. ELISA is performed inside two microtiter plates for MAb-cTnI and MAb-cTnT. For each plate, monoclonal antibodies are tested by various concentrations of cTnI and cTnT ranging from 0-6400 µg/l. The binding selectivity and level of detection between monoclonal antibodies and antigen are determined through visual observation based on the color change inside each well on the plate. ELISA reader is further used to quantitatively measured the optical density of the color changes, thus produced more accurate reading. The results from this experiment are utilized to justify the use of these monoclonal antibodies as bio-receptors for cardiac troponin detection by using field-effect transistor (FET)-based biosensors coupled with substrate-gate in the future.

Crude oil exposures reveal roles for intracellular calcium cycling in haddock craniofacial and cardiac development

PubMed Central

Sørhus, Elin; Incardona, John P.; Karlsen, Ørjan; Linbo, Tiffany; Sørensen, Lisbet; Nordtug, Trond; van der Meeren, Terje; Thorsen, Anders; Thorbjørnsen, Maja; Jentoft, Sissel; Edvardsen, Rolf B.; Meier, Sonnich

2016-01-01

Recent studies have shown that crude oil exposure affects cardiac development in fish by disrupting excitation-contraction (EC) coupling. We previously found that eggs of Atlantic haddock (Melanogrammus aeglefinus) bind dispersed oil droplets, potentially leading to more profound toxic effects from uptake of polycyclic aromatic hydrocarbons (PAHs). Using lower concentrations of dispersed crude oil (0.7–7 μg/L ∑PAH), here we exposed a broader range of developmental stages over both short and prolonged durations. We quantified effects on cardiac function and morphogenesis, characterized novel craniofacial defects, and examined the expression of genes encoding potential targets underlying cardiac and craniofacial defects. Because of oil droplet binding, a 24-hr exposure was sufficient to create severe cardiac and craniofacial abnormalities. The specific nature of the craniofacial abnormalities suggests that crude oil may target common craniofacial and cardiac precursor cells either directly or indirectly by affecting ion channels and intracellular calcium in particular. Furthermore, down-regulation of genes encoding specific components of the EC coupling machinery suggests that crude oil disrupts excitation-transcription coupling or normal feedback regulation of ion channels blocked by PAHs. These data support a unifying hypothesis whereby depletion of intracellular calcium pools by crude oil-derived PAHs disrupts several pathways critical for organogenesis in fish. PMID:27506155

Endothelin receptor B, a candidate gene from human studies at high altitude, improves cardiac tolerance to hypoxia in genetically engineered heterozygote mice

PubMed Central

Stobdan, Tsering; Zhou, Dan; Ao-Ieong, Eilleen; Ortiz, Daniel; Ronen, Roy; Hartley, Iain; Gan, Zhuohui; McCulloch, Andrew D.; Bafna, Vineet; Cabrales, Pedro; Haddad, Gabriel G.

2015-01-01

To better understand human adaptation to stress, and in particular to hypoxia, we took advantage of one of nature’s experiments at high altitude (HA) and studied Ethiopians, a population that is well-adapted to HA hypoxic stress. Using whole-genome sequencing, we discovered that EDNRB (Endothelin receptor type B) is a candidate gene involved in HA adaptation. To test whether EDNRB plays a critical role in hypoxia tolerance and adaptation, we generated EdnrB knockout mice and found that when EdnrB−/+ heterozygote mice are treated with lower levels of oxygen (O2), they tolerate various levels of hypoxia (even extreme hypoxia, e.g., 5% O2) very well. For example, they maintain ejection fraction, cardiac contractility, and cardiac output in severe hypoxia. Furthermore, O2 delivery to vital organs was significantly higher and blood lactate was lower in EdnrB−/+ compared with wild type in hypoxia. Tissue hypoxia in brain, heart, and kidney was lower in EdnrB−/+ mice as well. These data demonstrate that a lower level of EDNRB significantly improves cardiac performance and tissue perfusion under various levels of hypoxia. Transcriptomic profiling of left ventricles revealed three specific genes [natriuretic peptide type A (Nppa), sarcolipin (Sln), and myosin light polypeptide 4 (Myl4)] that were oppositely expressed (q < 0.05) between EdnrB−/+ and wild type. Functions related to these gene networks were consistent with a better cardiac contractility and performance. We conclude that EDNRB plays a key role in hypoxia tolerance and that a lower level of EDNRB contributes, at least in part, to HA adaptation in humans. PMID:26240367

Cardiovascular adaptation to extrauterine life after intrauterine growth restriction.

PubMed

Rodriguez-Guerineau, Luciana; Perez-Cruz, Miriam; Gomez Roig, María D; Cambra, Francisco J; Carretero, Juan; Prada, Fredy; Gómez, Olga; Crispi, Fátima; Bartrons, Joaquim

2018-02-01

Introduction The adaptive changes of the foetal heart in intrauterine growth restriction can persist postnatally. Data regarding its consequences for early circulatory adaptation to extrauterine life are scarce. The aim of this study was to assess cardiac morphometry and function in newborns with late-onset intrauterine growth restriction to test the hypothesis that intrauterine growth restriction causes cardiac shape and functional changes at birth. A comprehensive echocardiographic study was performed in 25 neonates with intrauterine growth restriction and 25 adequate-for-gestational-age neonates. Compared with controls, neonates with intrauterine growth restriction had more globular ventricles, lower longitudinal tricuspid annular motion, and higher left stroke volume without differences in the heart rate. Neonates with intrauterine growth restriction also showed subclinical signs of diastolic dysfunction in the tissue Doppler imaging with lower values of early (e') diastolic annular peak velocities in the septal annulus. Finally, the Tei index in the tricuspid annulus was higher in the intrauterine growth restriction group. Neonates with history of intrauterine growth restriction showed cardiac remodelling and signs of systolic and diastolic dysfunction. Overall, there was a significant tendency to worse cardiac function results in the right heart. The adaptation to extrauterine life occurred with more globular hearts, higher stroke volumes but a similar heart rate compared to adequate-for-gestational-age neonates.

Ageing and cardiorespiratory response to hypoxia.

PubMed

Lhuissier, François J; Canouï-Poitrine, Florence; Richalet, Jean-Paul

2012-11-01

The risk of severe altitude-induced diseases is related to ventilatory and cardiac responses to hypoxia and is dependent on sex, age and exercise training status. However, it remains unclear how ageing modifies these physiological adaptations to hypoxia. We assessed the physiological responses to hypoxia with ageing through a cross-sectional 20 year study including 4675 subjects (2789 men, 1886 women; 14-85 years old) and a longitudinal study including 30 subjects explored at a mean 10.4 year interval. The influence of sex, training status and menopause was evaluated. The hypoxia-induced desaturation and the ventilatory and cardiac responses to hypoxia at rest and exercise were measured. In men, ventilatory response to hypoxia increased (P < 0.002), while desaturation was less pronounced (P < 0.001) with ageing. Cardiac response to hypoxia was blunted with ageing in both sexes (P < 0.001). Similar results were found in the longitudinal study, with a decrease in cardiac and an increase in ventilatory response to hypoxia with ageing. These adaptive responses were less pronounced or absent in post-menopausal women (P < 0.01). At exercise, desaturation was greater in trained subjects but cardiac and ventilatory responses to hypoxia were preserved by training, especially in elderly people. In conclusion, respiratory response to hypoxia and blood oxygenation improve with ageing in men while cardiac response is blunted with ageing in both sexes. Training aggravates desaturation at exercise in hypoxia, improves the ventilatory response and limits the ageing-induced blunting of cardiac response to hypoxia. Training limits the negative effects of menopause in cardiorespiratory adaptations to hypoxia.

Tissue-Engineering for the Study of Cardiac Biomechanics

PubMed Central

Ma, Stephen P.; Vunjak-Novakovic, Gordana

2016-01-01

The notion that both adaptive and maladaptive cardiac remodeling occurs in response to mechanical loading has informed recent progress in cardiac tissue engineering. Today, human cardiac tissues engineered in vitro offer complementary knowledge to that currently provided by animal models, with profound implications to personalized medicine. We review here recent advances in the understanding of the roles of mechanical signals in normal and pathological cardiac function, and their application in clinical translation of tissue engineering strategies to regenerative medicine and in vitro study of disease. PMID:26720588

Mitochondrial adaptations to physiological vs. pathological cardiac hypertrophy

PubMed Central

Abel, E. Dale; Doenst, Torsten

2011-01-01

Cardiac hypertrophy is a stereotypic response of the heart to increased workload. The nature of the workload increase may vary depending on the stimulus (repetitive, chronic, pressure, or volume overload). If the heart fully adapts to the new loading condition, the hypertrophic response is considered physiological. If the hypertrophic response is associated with the ultimate development of contractile dysfunction and heart failure, the response is considered pathological. Although divergent signalling mechanisms may lead to these distinct patterns of hypertrophy, there is some overlap. Given the close relationship between workload and energy demand, any form of cardiac hypertrophy will impact the energy generation by mitochondria, which are the key organelles for cellular ATP production. Significant changes in the expression of nuclear and mitochondrially encoded transcripts that impact mitochondrial function as well as altered mitochondrial proteome composition and mitochondrial energetics have been described in various forms of cardiac hypertrophy. Here, we review mitochondrial alterations in pathological and physiological hypertrophy. We suggest that mitochondrial adaptations to pathological and physiological hypertrophy are distinct, and we shall review potential mechanisms that might account for these differences. PMID:21257612

ERBB2 Deficiency Alters an E2F-1-Dependent Adaptive Stress Response and Leads to Cardiac Dysfunction

PubMed Central

Perry, Marie-Claude; Dufour, Catherine R.; Eichner, Lillian J.; Tsang, David W. K.; Deblois, Geneviève; Muller, William J.

2014-01-01

The tyrosine kinase receptor ERBB2 is required for normal development of the heart and is a potent oncogene in breast epithelium. Trastuzumab, a monoclonal antibody targeting ERBB2, improves the survival of breast cancer patients, but cardiac dysfunction is a major side effect of the drug. The molecular mechanisms underlying how ERBB2 regulates cardiac function and why trastuzumab is cardiotoxic remain poorly understood. We show here that ERBB2 hypomorphic mice develop cardiac dysfunction that mimics the side effects observed in patients treated with trastuzumab. We demonstrate that this phenotype is related to the critical role played by ERBB2 in cardiac homeostasis and physiological hypertrophy. Importantly, genetic and therapeutic reduction of ERBB2 activity in mice, as well as ablation of ERBB2 signaling by trastuzumab or siRNAs in human cardiomyocytes, led to the identification of an impaired E2F-1-dependent genetic program critical for the cardiac adaptive stress response. These findings demonstrate the existence of a previously unknown mechanistic link between ERBB2 and E2F-1 transcriptional activity in heart physiology and trastuzumab-induced cardiac dysfunction. PMID:25246633

Syndecan-4 Signaling Is Required for Exercise-Induced Cardiac Hypertrophy

PubMed Central

Xie, Jun; He, Guixin; Chen, Qinhua; Sun, Jiayin; Dai, Qin; Lu, Jianrong; Li, Guannan; Wu, Han; Li, Ran; Chen, Jianzhou; Xu, Wei; Xu, Biao

2016-01-01

Cardiac hypertrophy can be broadly classified as either physiological or pathological. Physiological stimuli such as exercise cause adaptive cardiac hypertrophy and normal heart function. Pathological stimuli including hypertension and aortic valvular stenosis cause maladaptive cardiac remodeling and ultimately heart failure. Syndecan-4 (synd4) is a transmembrane proteoglycan identified as being involved in cardiac adaptation after injury, but whether it takes part in physiological cardiac hypertrophy is unclear. We observed upregulation of synd4 in exercise-induced hypertrophic myocardium. To evaluate the role of synd4 in the physiological form of cardiac hypertrophy, mice lacking synd4 (synd4–/–) were exercised by swimming for 4 wks. Ultrasonic cardiogram (UCG) and histological analysis revealed that swimming induced the hypertrophic phenotype but was blunted in synd4–/– compared with wild-type (WT) mice. The swimming-induced activation of Akt, a key molecule in physiological hypertrophy was also more decreased than in WT controls. In cultured cardiomyocytes, synd4 overexpression could induce cell enlargement, protein synthesis and distinct physiological molecular alternation. Akt activation also was observed in synd4-overexpressed cardiomyocytes. Furthermore, inhibition of protein kinase C (PKC) prevented the synd4-induced hypertrophic phenotype and Akt phosphorylation. This study identified an essential role of synd4 in mediation of physiological cardiac hypertrophy. PMID:26835698

Association of cardiac myosin binding protein-C with the ryanodine receptor channel: putative retrograde regulation?

PubMed

Stanczyk, Paulina J; Seidel, Monika; White, Judith; Viero, Cedric; George, Christopher H; Zissimopoulos, Spyros; Lai, F Anthony

2018-06-21

The cardiac muscle ryanodine receptor-Ca 2+ release channel (RyR2) constitutes the sarcoplasmic reticulum (SR) Ca 2+ efflux mechanism that initiates myocyte contraction, while cardiac myosin binding protein-C (cMyBP-C) mediates regulation of acto-myosin cross-bridge cycling. In this report, we provide the first evidence for the presence of direct interaction between these two proteins, forming a RyR2:cMyBP-C complex. The C-terminus of cMyBP-C binds with the RyR2 N-terminus in mammalian cells and is not mediated by a fibronectin-like domain. Notably, we detected complex formation between both recombinant cMyBP-C and RyR2, as well as with the native proteins in cardiac tissue. Cellular Ca 2+ dynamics in HEK293 cells is altered upon co-expression of cMyBP-C and RyR2, with lowered frequency of RyR2-mediated spontaneous Ca 2+ oscillations, suggesting cMyBP-C exerts a potential inhibitory effect on RyR2-dependent Ca 2+ release. Discovery of a functional RyR2 association with cMyBP-C provides direct evidence for a putative mechanistic link between cytosolic soluble cMyBP-C and SR-mediated Ca 2+ release, via RyR2. Importantly, this interaction may have clinical relevance to the observed cMyBP-C and RyR2 dysfunction in cardiac pathologies, such as hypertrophic cardiomyopathy. © 2018. Published by The Company of Biologists Ltd.

Interstrain variation in cardiac and respiratory adaptation to repeated ozone and particulate matter exposures.

PubMed

Hamade, Ali K; Tankersley, Clarke G

2009-04-01

Increased ambient particulate matter (PM) is associated with adverse cardiovascular and respiratory outcomes, as demonstrated by epidemiology studies. Several studies have investigated the role of copollutants, such as ozone (O(3)), in this association. It is accepted that physiological adaptation involving the respiratory system occurs with repeated exposures to O(3). We hypothesize that adaptation to PM and O(3) varies among different inbred mouse strains, and cardiopulmonary adaptation to O(3) is a synchronized response between the cardiac and respiratory systems. Heart rate (HR), HR variability (HRV), and the magnitude and pattern of breathing were simultaneously measured by implanted telemeters and by plethysmography in three inbred mouse strains: C57Bl/6J (B6), C3H/HeJ (HeJ), and C3H/HeOuJ (OuJ). Physiological responses were assessed during dual exposures to filtered air (FA), O(3) (576 +/- 32 parts/billion), and/or carbon black (CB; 556 +/- 34 mug/m(3)). Exposures were repeated for 3 consecutive days. While each strain showed significant reductions in HR during CB with O(3) preexposure (O(3)CB) on day 1, prominent HRV responses were observed in only HeJ and OuJ mice. Each strain also differed in their adaptation profile in response to repeated O(3)CB exposures. Whereas B6 mice showed rapid adaptation in HR after day 1, HeJ mice generally showed more moderate HR and HRV adaptation after day 2 of exposure. Unlike either B6 or HeJ strains, OuJ mice showed little evidence of HR or HRV adaptation to repeated O(3)CB exposure. Adaptation profiles between HR regulation and breathing characteristics were strongly correlated, but these associations also varied significantly among strains. These findings suggest that genetic factors determine the responsivity and adaptation of the cardiac and respiratory systems to repeated copollutant exposures. During O(3)CB exposure, adaptation of cardiac and respiratory systems is markedly synchronized, which may explain a potential mechanism for adverse effects of PM on heart function.

Interstrain variation in cardiac and respiratory adaptation to repeated ozone and particulate matter exposures

PubMed Central

Hamade, Ali K.; Tankersley, Clarke G.

2009-01-01

Increased ambient particulate matter (PM) is associated with adverse cardiovascular and respiratory outcomes, as demonstrated by epidemiology studies. Several studies have investigated the role of copollutants, such as ozone (O3), in this association. It is accepted that physiological adaptation involving the respiratory system occurs with repeated exposures to O3. We hypothesize that adaptation to PM and O3 varies among different inbred mouse strains, and cardiopulmonary adaptation to O3 is a synchronized response between the cardiac and respiratory systems. Heart rate (HR), HR variability (HRV), and the magnitude and pattern of breathing were simultaneously measured by implanted telemeters and by plethysmography in three inbred mouse strains: C57Bl/6J (B6), C3H/HeJ (HeJ), and C3H/HeOuJ (OuJ). Physiological responses were assessed during dual exposures to filtered air (FA), O3 (576 ± 32 parts/billion), and/or carbon black (CB; 556 ± 34 μg/m3). Exposures were repeated for 3 consecutive days. While each strain showed significant reductions in HR during CB with O3 preexposure (O3CB) on day 1, prominent HRV responses were observed in only HeJ and OuJ mice. Each strain also differed in their adaptation profile in response to repeated O3CB exposures. Whereas B6 mice showed rapid adaptation in HR after day 1, HeJ mice generally showed more moderate HR and HRV adaptation after day 2 of exposure. Unlike either B6 or HeJ strains, OuJ mice showed little evidence of HR or HRV adaptation to repeated O3CB exposure. Adaptation profiles between HR regulation and breathing characteristics were strongly correlated, but these associations also varied significantly among strains. These findings suggest that genetic factors determine the responsivity and adaptation of the cardiac and respiratory systems to repeated copollutant exposures. During O3CB exposure, adaptation of cardiac and respiratory systems is markedly synchronized, which may explain a potential mechanism for adverse effects of PM on heart function. PMID:19158411

Polymorphisms in Fibronectin Binding Protein A of Staphylococcus Aureus are Associated with Infection of Cardiovascular Devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lower, Steven; Lamlertthon, Supaporn; Casillas-Ituarte, Nadia

Medical implants, like cardiovascular devices, improve the quality of life for countless individuals but may become infected with bacteria like Staphylococcus aureus. Such infections take the form of a bio-film, a structured community of bacterial cells adherent to the surface of a solid substrate. Every bio-film begins with an attractive force or bond between bacterium and substratum. We used atomic force microscopy to probe experimentally forces between a fibronectin-coated surface (i.e., proxy for an implanted cardiac device) and fibronectin-binding receptors on the surface of individual living bacteria from each of 80 clinical isolates of S. aureus. These isolates originated frommore » humans with infected cardiac devices (CDI; n = 26), uninfected cardiac devices (n = 20), and the anterior nares of asymptomatic subjects (n = 34). CDI isolates exhibited a distinct bindingforce signature and had speci!c single amino acid polymorphisms in fibronectin-binding protein A corresponding to E652D, H782Q, and K786N. In silico molecular dynamics simulations demonstrate that residues D652, Q782, and N786 in fibronectin-binding protein A form extra hydrogen bonds with fibronectin, complementing the higher binding force and energy measured by atomic force microscopy for the CDI isolates. This study is significant, because it links pathogenic bacteria biofilms from the length scale of bonds acting across a nanometer-scale space to the clinical presentation of disease at the human dimension.« less

Increased Efferent Cardiac Sympathetic Nerve Activity and Defective Intrinsic Heart Rate Regulation in Type 2 Diabetes.

PubMed

Thaung, H P Aye; Baldi, J Chris; Wang, Heng-Yu; Hughes, Gillian; Cook, Rosalind F; Bussey, Carol T; Sheard, Phil W; Bahn, Andrew; Jones, Peter P; Schwenke, Daryl O; Lamberts, Regis R

2015-08-01

Elevated sympathetic nerve activity (SNA) coupled with dysregulated β-adrenoceptor (β-AR) signaling is postulated as a major driving force for cardiac dysfunction in patients with type 2 diabetes; however, cardiac SNA has never been assessed directly in diabetes. Our aim was to measure the sympathetic input to and the β-AR responsiveness of the heart in the type 2 diabetic heart. In vivo recording of SNA of the left efferent cardiac sympathetic branch of the stellate ganglion in Zucker diabetic fatty rats revealed an elevated resting cardiac SNA and doubled firing rate compared with nondiabetic rats. Ex vivo, in isolated denervated hearts, the intrinsic heart rate was markedly reduced. Contractile and relaxation responses to β-AR stimulation with dobutamine were compromised in externally paced diabetic hearts, but not in diabetic hearts allowed to regulate their own heart rate. Protein levels of left ventricular β1-AR and Gs (guanine nucleotide binding protein stimulatory) were reduced, whereas left ventricular and right atrial β2-AR and Gi (guanine nucleotide binding protein inhibitory regulatory) levels were increased. The elevated resting cardiac SNA in type 2 diabetes, combined with the reduced cardiac β-AR responsiveness, suggests that the maintenance of normal cardiovascular function requires elevated cardiac sympathetic input to compensate for changes in the intrinsic properties of the diabetic heart. © 2015 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.

Transforming growth factor-β inhibits myocardial PPARγ expression in pressure overload-induced cardiac fibrosis and remodeling in mice

PubMed Central

Gong, Kaizheng; Chen, Yiu-Fai; Li, Peng; Lucas, Jason A.; Hage, Fadi G.; Yang, Qinglin; Nozell, Susan E.; Oparil, Suzanne; Xing, Dongqi

2012-01-01

Objectives Pharmacological activation of peroxisome proliferator-activated receptor gamma (PPARγ) has been shown to attenuate pressure overload-induced cardiac fibrosis, suggesting that PPARγ has an antifibrotic effect. This study tested the hypothesis that there is a functional interaction between transforming growth factor-β (TGF-β) signaling and endogenous PPARγ expression in cardiac fibroblasts and pressure overloaded heart. Methods and results We observed that, in response to pressure overload induced by transverse aortic constriction, left-ventricular PPARγ protein levels were decreased in wild-type mice, but increased in mice with an inducible overexpression of dominant negative mutation of the human TGF-β type II receptor (DnTGFβRII), in which TGF-β signaling is blocked. In isolated mouse cardiac fibroblasts, we demonstrated that TGF-β1 treatment decreased steady state PPARγ mRNA (−34%) and protein (−52%) levels, as well as PPARγ transcriptional activity (−53%). Chromatin immunoprecipitation analysis showed that TGF-β1 treatment increased binding of Smad2/3, Smad4 and histone deacetylase 1, and decreased binding of acetylated histone 3 to the PPARγ promoter in cardiac fibroblasts. Both pharmacological activation and overexpression of PPARγ significantly inhibited TGF-β1-induced extracellular matrix molecule expression in isolated cardiac fibroblasts, whereas treatment with the PPARγ agonist rosiglitazone inhibited, and treatment with the PPARγ antagonist T0070907 exacerbated chronic pressure overload-induced cardiac fibrosis and remodeling in wild-type mice in vivo. Conclusion These data provide strong evidence that TGF-β1 directly suppresses PPARγ expression in cardiac fibroblasts via a transcriptional mechanism and suggest that the down-regulation of endogenous PPARγ expression by TGF-β may be involved in pressure overload-induced cardiac fibrosis. PMID:21836474

Hypoxia signaling controls postnatal changes in cardiac mitochondrial morphology and function

PubMed Central

Neary, Marianne T.; Ng, Keat-Eng; Ludtmann, Marthe H.R.; Hall, Andrew R.; Piotrowska, Izabela; Ong, Sang-Bing; Hausenloy, Derek J.; Mohun, Timothy J.; Abramov, Andrey Y.; Breckenridge, Ross A.

2014-01-01

Fetal cardiomyocyte adaptation to low levels of oxygen in utero is incompletely understood, and is of interest as hypoxia tolerance is lost after birth, leading to vulnerability of adult cardiomyocytes. It is known that cardiac mitochondrial morphology, number and function change significantly following birth, although the underlying molecular mechanisms and physiological stimuli are undefined. Here we show that the decrease in cardiomyocyte HIF-signaling in cardiomyocytes immediately after birth acts as a physiological switch driving mitochondrial fusion and increased postnatal mitochondrial biogenesis. We also investigated mechanisms of ATP generation in embryonic cardiac mitochondria. We found that embryonic cardiac cardiomyocytes rely on both glycolysis and the tricarboxylic acid cycle to generate ATP, and that the balance between these two metabolic pathways in the heart is controlled around birth by the reduction in HIF signaling. We therefore propose that the increase in ambient oxygen encountered by the neonate at birth acts as a key physiological stimulus to cardiac mitochondrial adaptation. PMID:24984146

Cardiac Alpha1-Adrenergic Receptors: Novel Aspects of Expression, Signaling Mechanisms, Physiologic Function, and Clinical Importance

PubMed Central

O’Connell, Timothy D.; Jensen, Brian C.; Baker, Anthony J.

2014-01-01

Adrenergic receptors (AR) are G-protein-coupled receptors (GPCRs) that have a crucial role in cardiac physiology in health and disease. Alpha1-ARs signal through Gαq, and signaling through Gq, for example, by endothelin and angiotensin receptors, is thought to be detrimental to the heart. In contrast, cardiac alpha1-ARs mediate important protective and adaptive functions in the heart, although alpha1-ARs are only a minor fraction of total cardiac ARs. Cardiac alpha1-ARs activate pleiotropic downstream signaling to prevent pathologic remodeling in heart failure. Mechanisms defined in animal and cell models include activation of adaptive hypertrophy, prevention of cardiac myocyte death, augmentation of contractility, and induction of ischemic preconditioning. Surprisingly, at the molecular level, alpha1-ARs localize to and signal at the nucleus in cardiac myocytes, and, unlike most GPCRs, activate “inside-out” signaling to cause cardioprotection. Contrary to past opinion, human cardiac alpha1-AR expression is similar to that in the mouse, where alpha1-AR effects are seen most convincingly in knockout models. Human clinical studies show that alpha1-blockade worsens heart failure in hypertension and does not improve outcomes in heart failure, implying a cardioprotective role for human alpha1-ARs. In summary, these findings identify novel functional and mechanistic aspects of cardiac alpha1-AR function and suggest that activation of cardiac alpha1-AR might be a viable therapeutic strategy in heart failure. PMID:24368739

Interleukin 1 and Tumor Necrosis Factor Inhibit Cardiac Myocyte β -adrenergic Responsiveness

NASA Astrophysics Data System (ADS)

Gulick, Tod; Chung, Mina K.; Pieper, Stephen J.; Lange, Louis G.; Schreiner, George F.

1989-09-01

Reversible congestive heart failure can accompany cardiac allograft rejection and inflammatory myocarditis, conditions associated with an immune cell infiltrate of the myocardium. To determine whether immune cell secretory products alter cardiac muscle metabolism without cytotoxicity, we cultured cardiac myocytes in the presence of culture supernatants from activated immune cells. We observed that these culture supernatants inhibit β -adrenergic agonist-mediated increases in cultured cardiac myocyte contractility and intracellular cAMP accumulation. The myocyte contractile response to increased extracellular Ca2+ concentration is unaltered by prior exposure to these culture supernatants, as is the increase in myocyte intracellular cAMP concentration in response to stimulation with forskolin, a direct adenyl cyclase activator. Inhibition occurs in the absence of alteration in β -adrenergic receptor density or ligand binding affinity. Suppressive activity is attributable to the macrophage-derived cytokines interleukin 1 and tumor necrosis factor. Thus, these observations describe a role for defined cytokines in regulating the hormonal responsiveness and function of contractile cells. The effects of interleukin 1 and tumor necrosis factor on intracellular cAMP accumulation may be a model for immune modulation of other cellular functions dependent upon cyclic nucleotide metabolism. The uncoupling of agonist-occupied receptors from adenyl cyclase suggests that β -receptor or guanine nucleotide binding protein function is altered by the direct or indirect action of cytokines on cardiac muscle cells.

Clinical evaluation of point-of-care-testing of heart-type fatty acid-binding protein (H-FABP) for the diagnosis of acute myocardial infarction.

PubMed

Tanaka, Takao; Sohmiya, Ko-ichi; Kitaura, Yasushi; Takeshita, Hitoshi; Morita, Hiroshi; Ohkaru, Yasuhiko; Asayama, Kumiko; Kimura, Hiroshi

2006-01-01

The present study was carried out for clinical evaluation of point-of-care-testing (POCT) of heart-type fatty acid-binding protein (H-FABP), Rapicheck H-FABP, for the diagnosis of acute myocardial infarction (AMI), in comparison with conventional cardiac biochemical markers such as myoglobin, creatine kinase isoenzyme MB (CK-MB), and cardiac troponin T. Whole blood samples from patients with confirmed AMI (n = 53), patients with non-AMI cardiac diseases (n = 24), and patients with non-cardiac diseases with chest pain (n = 6) were used. When a test line appeared within 15 min after the addition of 150 microL of whole blood, it was designated to be positive for H-FABP. A control line indicates a proper use of the test. On the other hand, when no test line appeared, it was negative. In the superacute phase of AMI within 3 hours, the diagnostic sensitivity of H-FABP was 93.1%, which was the highest of the four markers compared here. The diagnostic specificity in the phase for H-FABP was 64.3%, while it was 100% with cardiac troponin T. The POCT of H-FABP is thought to be practical for the detection of cardiac damage and effective for the diagnosis of AMI in superacute phase within 3 hours and/or 6 hours.

Adaptive control of bivalirudin in the cardiac intensive care unit.

PubMed

Zhao, Qi; Edrich, Thomas; Paschalidis, Ioannis Ch

2015-02-01

Bivalirudin is a direct thrombin inhibitor used in the cardiac intensive care unit when heparin is contraindicated due to heparin-induced thrombocytopenia. Since it is not a commonly used drug, clinical experience with its dosing is sparse. In earlier work [1], we developed a dynamic system model that accurately predicts the effect of bivalirudin given dosage over time and patient physiological characteristics. This paper develops adaptive dosage controllers that regulate its effect to desired levels. To that end, and in the case that bivalirudin model parameters are available, we develop a Model Reference Control law. In the case that model parameters are unknown, an indirect Model Reference Adaptive Control scheme is applied to estimate model parameters first and then adapt the controller. Alternatively, direct Model Reference Adaptive Control is applied to adapt the controller directly without estimating model parameters first. Our algorithms are validated using actual patient data from a large hospital in the Boston area.

CRYO-EM STRUCTURES OF THE ACTIN:TROPOMYOSIN FILAMENT REVEAL THE MECHANISM FOR THE TRANSITION FROM C- TO M-STATE

PubMed Central

Sousa, Duncan R.; Stagg, Scott M.; Stroupe, M. Elizabeth

2013-01-01

Tropomyosin is a key factor in the molecular mechanisms that regulate the binding of myosin motors to actin filaments in most eukaryotic cells. This regulation is achieved by the azimuthal repositioning of tropomyosin along the actin:tropomyosin:troponin thin filament to block or expose myosin binding sites on actin. In striated muscle, including involuntary cardiac muscle, tropomyosin regulates muscle contraction by coupling Ca2+ binding to troponin with myosin binding to the thin filament. In smooth muscle, the switch is the post-translational modification of the myosin. Depending on the activation state of troponin and the binding state of myosin, tropomyosin can occupy the blocked, closed, or open position on actin. Using native cryogenic 3DEM, we have directly resolved and visualized cardiac and gizzard muscle tropomyosin on filamentous actin in the position that corresponds to the closed state. From the 8-Å resolution structure of the reconstituted Ac:Tm filament formed with gizzard-derived Tm we discuss two possible mechanisms for the transition from closed to open state and describe the role Tm plays in blocking myosin tight binding in the closed state position. PMID:24021812

AKAP-scaffolding proteins and regulation of cardiac physiology

PubMed Central

Mauban, JRH; O'Donnell, M; Warrier, S; Manni, S; Bond, M

2009-01-01

A kinase anchoring proteins (AKAPs) compose a growing list of diverse but functionally related proteins defined by their ability to bind to the regulatory subunit of protein kinase A. AKAPs perform an integral role in the spatiotemporal modulation of a multitude of cellular signaling pathways. This review highlights the extensive role of AKAPs in cardiac excitation/contraction coupling and cardiac physiology. The literature shows that particular AKAPs are involved in cardiac Ca2+ influx, release, re-uptake, and myocyte repolarization. Studies have also suggested roles for AKAPs in cardiac remodeling. Transgenic studies show functional effects of AKAPs, not only in the cardiovascular system, but in other organ systems as well. PMID:19364910

Pathophysiology of cardiac hypertrophy and heart failure: signaling pathways and novel therapeutic targets.

PubMed

Tham, Yow Keat; Bernardo, Bianca C; Ooi, Jenny Y Y; Weeks, Kate L; McMullen, Julie R

2015-09-01

The onset of heart failure is typically preceded by cardiac hypertrophy, a response of the heart to increased workload, a cardiac insult such as a heart attack or genetic mutation. Cardiac hypertrophy is usually characterized by an increase in cardiomyocyte size and thickening of ventricular walls. Initially, such growth is an adaptive response to maintain cardiac function; however, in settings of sustained stress and as time progresses, these changes become maladaptive and the heart ultimately fails. In this review, we discuss the key features of pathological cardiac hypertrophy and the numerous mediators that have been found to be involved in the pathogenesis of cardiac hypertrophy affecting gene transcription, calcium handling, protein synthesis, metabolism, autophagy, oxidative stress and inflammation. We also discuss new mediators including signaling proteins, microRNAs, long noncoding RNAs and new findings related to the role of calcineurin and calcium-/calmodulin-dependent protein kinases. We also highlight mediators and processes which contribute to the transition from adaptive cardiac remodeling to maladaptive remodeling and heart failure. Treatment strategies for heart failure commonly include diuretics, angiotensin converting enzyme inhibitors, angiotensin II receptor blockers and β-blockers; however, mortality rates remain high. Here, we discuss new therapeutic approaches (e.g., RNA-based therapies, dietary supplementation, small molecules) either entering clinical trials or in preclinical development. Finally, we address the challenges that remain in translating these discoveries to new and approved therapies for heart failure.

Adaptive servo ventilation improves Cheyne-Stokes respiration, cardiac function, and prognosis in chronic heart failure patients with cardiac resynchronization therapy.

PubMed

Miyata, Makiko; Yoshihisa, Akiomi; Suzuki, Satoshi; Yamada, Shinya; Kamioka, Masashi; Kamiyama, Yoshiyuki; Yamaki, Takayoshi; Sugimoto, Koichi; Kunii, Hiroyuki; Nakazato, Kazuhiko; Suzuki, Hitoshi; Saitoh, Shu-ichi; Takeishi, Yasuchika

2012-09-01

Cheyne-Stokes respiration (CSR-CSA) is often observed in patients with chronic heart failure (CHF). Although cardiac resynchronization therapy (CRT) is effective for CHF patients with left ventricular dyssynchrony, it is still unclear whether adaptive servo ventilation (ASV) improves cardiac function and prognosis of CHF patients with CSR-CSA after CRT. Twenty two patients with CHF and CSR-CSA after CRT defibrillator (CRTD) implantation were enrolled in the present study and randomly assigned into two groups: 11 patients treated with ASV (ASV group) and 11 patients treated without ASV (non-ASV group). Measurement of plasma B-type natriuretic peptide (BNP) levels (before 3, and 6 months later) and echocardiography (before and 6 months) were performed in each group. Patients were followed up to register cardiac events (cardiac death and re-hospitalization) after discharge. In the ASV group, indices for apnea-hypopnea, central apnea, and oxyhemoglobin saturation were improved on ASV. BNP levels, cardiac systolic and diastolic function were improved with ASV treatment for 6 months. Importantly, the event-free rate was significantly higher in the ASV group than in the non-ASV group. ASV improves CSR-CSA, cardiac function, and prognosis in CHF patients with CRTD. Patients with CSR-CSA and post CRTD implantation would get benefits by treatment with ASV. Copyright © 2012 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.

Dioxygen and Metabolism; Dangerous Liaisons in Cardiac Function and Disease

PubMed Central

Angelini, Aude; Pi, Xinchun; Xie, Liang

2017-01-01

The heart must consume a significant amount of energy to sustain its contractile activity. Although the fuel demands are huge, the stock remains very low. Thus, in order to supply its daily needs, the heart must have amazing adaptive abilities, which are dependent on dioxygen availability. However, in myriad cardiovascular diseases, “fuel” depletion and hypoxia are common features, leading cardiomyocytes to favor low-dioxygen-consuming glycolysis rather than oxidation of fatty acids. This metabolic switch makes it challenging to distinguish causes from consequences in cardiac pathologies. Finally, despite the progress achieved in the past few decades, medical treatments have not improved substantially, either. In such a situation, it seems clear that much remains to be learned about cardiac diseases. Therefore, in this review, we will discuss how reconciling dioxygen availability and cardiac metabolic adaptations may contribute to develop full and innovative strategies from bench to bedside. PMID:29311974

Arjunolic acid, a peroxisome proliferator-activated receptor α agonist, regresses cardiac fibrosis by inhibiting non-canonical TGF-β signaling.

PubMed

Bansal, Trisha; Chatterjee, Emeli; Singh, Jasdeep; Ray, Arjun; Kundu, Bishwajit; Thankamani, V; Sengupta, Shantanu; Sarkar, Sagartirtha

2017-10-06

Cardiac hypertrophy and associated heart fibrosis remain a major cause of death worldwide. Phytochemicals have gained attention as alternative therapeutics for managing cardiovascular diseases. These include the extract from the plant Terminalia arjuna, which is a popular cardioprotectant and may prevent or slow progression of pathological hypertrophy to heart failure. Here, we investigated the mode of action of a principal bioactive T. arjuna compound, arjunolic acid (AA), in ameliorating hemodynamic load-induced cardiac fibrosis and identified its intracellular target. Our data revealed that AA significantly represses collagen expression and improves cardiac function during hypertrophy. We found that AA binds to and stabilizes the ligand-binding domain of peroxisome proliferator-activated receptor α (PPARα) and increases its expression during cardiac hypertrophy. PPARα knockdown during AA treatment in hypertrophy samples, including angiotensin II-treated adult cardiac fibroblasts and renal artery-ligated rat heart, suggests that AA-driven cardioprotection primarily arises from PPARα agonism. Moreover, AA-induced PPARα up-regulation leads to repression of TGF-β signaling, specifically by inhibiting TGF-β-activated kinase1 (TAK1) phosphorylation. We observed that PPARα directly interacts with TAK1, predominantly via PPARα N-terminal transactivation domain (AF-1) thereby masking the TAK1 kinase domain. The AA-induced PPARα-bound TAK1 level thereby shows inverse correlation with the phosphorylation level of TAK1 and subsequent reduction in p38 MAPK and NF-κBp65 activation, ultimately culminating in amelioration of excess collagen synthesis in cardiac hypertrophy. In conclusion, our findings unravel the mechanism of AA action in regressing hypertrophy-associated cardiac fibrosis by assigning a role of AA as a PPARα agonist that inactivates non-canonical TGF-β signaling. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Medico-legal perspectives on sudden cardiac death in young athletes.

PubMed

Oliva, Antonio; Grassi, Vincenzo M; Campuzano, Oscar; Brion, Maria; Arena, Vincenzo; Partemi, Sara; Coll, Monica; Pascali, Vincenzo L; Brugada, Josep; Carracedo, Angel; Brugada, Ramon

2017-03-01

Sudden cardiac death (SCD) in a young athlete represents a dramatic event, and an increasing number of medico-legal cases have addressed this topic. In addition to representing an ethical and medico-legal responsibility, prevention of SCD is directly correlated with accurate eligibility/disqualification decisions, with an inappropriate pronouncement in either direction potentially leading to legal controversy. This review summarizes the common causes of SCD in young athletes, divided into structural (hypertrophic cardiomyopathy, arrhythmogenic cardiomyopathy, congenital coronary artery anomalies, etc.), electrical (Brugada, congenital LQT, Wolf-Parkinson-White syndrome, etc.), and acquired cardiac abnormalities (myocarditis, etc.). In addition, the roles of hereditary cardiac anomalies in SCD in athletes and the effects of a positive result on them and their families are discussed. The medico-legal relevance of pre-participation screening is analyzed, and recommendations from the American Heart Association and European Society of Cardiology are compared. Finally, the main issues concerning the differentiation between physiologic cardiac adaptation in athletes and pathologic findings and, thereby, definition of the so-called gray zone, which is based on exact knowledge of the mechanism of cardiac remodeling including structural or functional adaptions, will be addressed.

The BMP pathway acts to directly regulate Tbx20 in the developing heart

PubMed Central

Mandel, Elizabeth M.; Kaltenbrun, Erin; Callis, Thomas E.; Zeng, Xin-Xin I.; Marques, Sara R.; Yelon, Deborah; Wang, Da-Zhi; Conlon, Frank L.

2010-01-01

TBX20 has been shown to be essential for vertebrate heart development. Mutations within the TBX20 coding region are associated with human congenital heart disease, and the loss of Tbx20 in a wide variety of model systems leads to cardiac defects and eventually heart failure. Despite the crucial role of TBX20 in a range of cardiac cellular processes, the signal transduction pathways that act upstream of Tbx20 remain unknown. Here, we have identified and characterized a conserved 334 bp Tbx20 cardiac regulatory element that is directly activated by the BMP/SMAD1 signaling pathway. We demonstrate that this element is both necessary and sufficient to drive cardiac-specific expression of Tbx20 in Xenopus, and that blocking SMAD1 signaling in vivo specifically abolishes transcription of Tbx20, but not that of other cardiac factors, such as Tbx5 and MHC, in the developing heart. We further demonstrate that activation of Tbx20 by SMAD1 is mediated by a set of novel, non-canonical, high-affinity SMAD-binding sites located within this regulatory element and that phospho-SMAD1 directly binds a non-canonical SMAD1 site in vivo. Finally, we show that these non-canonical sites are necessary and sufficient for Tbx20 expression in Xenopus, and that reporter constructs containing these sites are expressed in a cardiac-specific manner in zebrafish and mouse. Collectively, our findings define Tbx20 as a direct transcriptional target of the BMP/SMAD1 signaling pathway during cardiac maturation. PMID:20460370

Nitric Oxide Induces Cardiac Protection by Preventing Extracellular Matrix Degradation through the Complex Caveolin-3/EMMPRIN in Cardiac Myocytes

PubMed Central

Cuadrado, Irene; Castejon, Borja; Martin, Ana M.; Saura, Marta; Reventun-Torralba, Paula; Zamorano, Jose Luis

2016-01-01

Inhibition of Extracellular Matrix degradation by nitric oxide (NO) induces cardiac protection against coronary ischemia/reperfusion (IR). Glycosylation of Extracellular Matrix Metalloproteinase Inducer (EMMPRIN) stimulates enzymatic activation of matrix metalloproteinases (MMPs) in the heart, although the mechanisms leading to EMMPRIN glycosylation are poorly understood. We sought to determine if NO may induce cardiac protection by preventing glycosylation of EMMPRIN in a mouse model of IR. Here we found that Caveolin-3 binds to low glycosylated EMMPRIN (LG-EMMPRIN) in cardiac cells and in the hearts of healthy mice, whereas IR disrupted the complex in nitric oxide synthase 2 (NOS2) knockout (KO) mice. By contrast, the binding was partially restored when mice were fed with an NO donor (DEA-NO) in the drinking water, showing a significant reduction on infarct size (NOS2KO: 34.6±5 vs NOS2KO+DEA-NO: 20.7±9), in expression of matrix metalloproteinases, and cardiac performance was improved (left ventricular ejection fraction (LVEF). NOS2KO: 31±4 vs NOS2KO+DEA-NO: 46±6). The role of Caveolin-3/EMMPRIN in NO-mediated cardiac protection was further assayed in Caveolin-3 KO mice, showing no significant improvement on infarct size (Caveolin-3 KO: 34.8±3 vs Caveolin-3 KO+DEA-NO:33.7±5), or in the expression of MMPs, suggesting that stabilization of the complex Caveolin-3/LG-EMMPRIN may play a significant role in the cardioprotective effect of NO against IR. PMID:27649573

Nitric Oxide Induces Cardiac Protection by Preventing Extracellular Matrix Degradation through the Complex Caveolin-3/EMMPRIN in Cardiac Myocytes.

PubMed

Cuadrado, Irene; Castejon, Borja; Martin, Ana M; Saura, Marta; Reventun-Torralba, Paula; Zamorano, Jose Luis; Zaragoza, Carlos

2016-01-01

Inhibition of Extracellular Matrix degradation by nitric oxide (NO) induces cardiac protection against coronary ischemia/reperfusion (IR). Glycosylation of Extracellular Matrix Metalloproteinase Inducer (EMMPRIN) stimulates enzymatic activation of matrix metalloproteinases (MMPs) in the heart, although the mechanisms leading to EMMPRIN glycosylation are poorly understood. We sought to determine if NO may induce cardiac protection by preventing glycosylation of EMMPRIN in a mouse model of IR. Here we found that Caveolin-3 binds to low glycosylated EMMPRIN (LG-EMMPRIN) in cardiac cells and in the hearts of healthy mice, whereas IR disrupted the complex in nitric oxide synthase 2 (NOS2) knockout (KO) mice. By contrast, the binding was partially restored when mice were fed with an NO donor (DEA-NO) in the drinking water, showing a significant reduction on infarct size (NOS2KO: 34.6±5 vs NOS2KO+DEA-NO: 20.7±9), in expression of matrix metalloproteinases, and cardiac performance was improved (left ventricular ejection fraction (LVEF). NOS2KO: 31±4 vs NOS2KO+DEA-NO: 46±6). The role of Caveolin-3/EMMPRIN in NO-mediated cardiac protection was further assayed in Caveolin-3 KO mice, showing no significant improvement on infarct size (Caveolin-3 KO: 34.8±3 vs Caveolin-3 KO+DEA-NO:33.7±5), or in the expression of MMPs, suggesting that stabilization of the complex Caveolin-3/LG-EMMPRIN may play a significant role in the cardioprotective effect of NO against IR.

Efficacy outcome selection in the therapeutic hypothermia after pediatric cardiac arrest trials.

PubMed

Holubkov, Richard; Clark, Amy E; Moler, Frank W; Slomine, Beth S; Christensen, James R; Silverstein, Faye S; Meert, Kathleen L; Pollack, Murray M; Dean, J Michael

2015-01-01

The Therapeutic Hypothermia After Pediatric Cardiac Arrest trials will determine whether therapeutic hypothermia improves survival with good neurobehavioral outcome, as assessed by the Vineland Adaptive Behavior Scales Second Edition, in children resuscitated after cardiac arrest in the in-hospital and out-of-hospital settings. We describe the innovative efficacy outcome selection process during Therapeutic Hypothermia After Pediatric Cardiac Arrest protocol development. Consensus assessment of potential outcomes and evaluation timepoints. None. We evaluated practical and technical advantages of several follow-up timepoints and continuous/categorical outcome variants. Simulations estimated power assuming varying hypothermia benefit on mortality and on neurobehavioral function among survivors. Twelve months after arrest was selected as the optimal assessment timepoint for pragmatic and clinical reasons. Change in Vineland Adaptive Behavior Scales Second Edition from prearrest level, measured as quasicontinuous with death and vegetative status being worst-possible levels, yielded optimal statistical power. However, clinicians preferred simpler multicategorical or binary outcomes because of easier interpretability and favored outcomes based solely on postarrest status because of concerns about accurate parental assessment of prearrest status and differing clinical impact of a given Vineland Adaptive Behavior Scales Second Edition change depending on prearrest status. Simulations found only modest power loss from categorizing or dichotomizing quasicontinuous outcomes because of high expected mortality. The primary outcome selected was survival with 12-month Vineland Adaptive Behavior Scales Second Edition no less than two SD below a reference population mean (70 points), necessarily evaluated only among children with prearrest Vineland Adaptive Behavior Scales Second Edition greater than or equal to 70. Two secondary efficacy outcomes, 12-month survival and quasicontinuous Vineland Adaptive Behavior Scales Second Edition change from prearrest level, will be evaluated among all randomized children, including those with compromised function prearrest. Extensive discussion of optimal efficacy assessment timing, and of the advantages versus drawbacks of incorporating prearrest status and using quasicontinuous versus simpler outcomes, was highly beneficial to the final Therapeutic Hypothermia After Pediatric Cardiac Arrest design. A relatively simple, binary primary outcome evaluated at 12 months was selected, with two secondary outcomes that address the potential disadvantages of primary outcome.

Microtubule Actin Cross-Linking Factor 1 Regulates Cardiomyocyte Microtubule Distribution and Adaptation to Hemodynamic Overload

PubMed Central

Kwak, Dongmin; Wang, Huan; Liu, Xiaoyu; Hu, Xinli; Bache, Robert J.; Chen, Yingjie

2013-01-01

Aberrant cardiomyocyte microtubule growth is a feature of pressure overload induced cardiac hypertrophy believed to contribute to left ventricular (LV) dysfunction. Microtubule Actin Cross-linking Factor 1 (MACF1/Acf7) is a 600 kd spectraplakin that stabilizes and guides microtubule growth along actin filaments. MACF1 is expressed in the heart, but its impact on cardiac microtubules, and how this influences cardiac structure, function, and adaptation to hemodynamic overload is unknown. Here we used inducible cardiac-specific MACF1 knockout mice (MACF1 KO) to determine the impact of MACF1 on cardiac microtubules and adaptation to pressure overload (transverse aortic constriction (TAC).In adult mouse hearts, MACF1 expression was low under basal conditions, but increased significantly in response to TAC. While MACF1 KO had no observable effect on heart size or function under basal conditions, MACF1 KO exacerbated TAC induced LV hypertrophy, LV dilation and contractile dysfunction. Interestingly, subcellular fractionation of ventricular lysates revealed that MACF1 KO altered microtubule distribution in response to TAC, so that more tubulin was associated with the cell membrane fraction. Moreover, TAC induced microtubule redistribution into this cell membrane fraction in both WT and MACF1 KO mice correlated strikingly with the level of contractile dysfunction (r2 = 0.786, p<.001). MACF1 disruption also resulted in reduction of membrane caveolin 3 levels, and increased levels of membrane PKCα and β1 integrin after TAC, suggesting MACF1 function is important for spatial regulation of several physiologically relevant signaling proteins during hypertrophy. Together, these data identify for the first time, a role for MACF1 in cardiomyocyte microtubule distribution and in adaptation to hemodynamic overload. PMID:24086300

Microtubule Actin Cross-linking Factor 1 regulates cardiomyocyte microtubule distribution and adaptation to hemodynamic overload.

PubMed

Fassett, John T; Xu, Xin; Kwak, Dongmin; Wang, Huan; Liu, Xiaoyu; Hu, Xinli; Bache, Robert J; Chen, Yingjie

2013-01-01

Aberrant cardiomyocyte microtubule growth is a feature of pressure overload induced cardiac hypertrophy believed to contribute to left ventricular (LV) dysfunction. Microtubule Actin Cross-linking Factor 1 (MACF1/Acf7) is a 600 kd spectraplakin that stabilizes and guides microtubule growth along actin filaments. MACF1 is expressed in the heart, but its impact on cardiac microtubules, and how this influences cardiac structure, function, and adaptation to hemodynamic overload is unknown. Here we used inducible cardiac-specific MACF1 knockout mice (MACF1 KO) to determine the impact of MACF1 on cardiac microtubules and adaptation to pressure overload (transverse aortic constriction (TAC).In adult mouse hearts, MACF1 expression was low under basal conditions, but increased significantly in response to TAC. While MACF1 KO had no observable effect on heart size or function under basal conditions, MACF1 KO exacerbated TAC induced LV hypertrophy, LV dilation and contractile dysfunction. Interestingly, subcellular fractionation of ventricular lysates revealed that MACF1 KO altered microtubule distribution in response to TAC, so that more tubulin was associated with the cell membrane fraction. Moreover, TAC induced microtubule redistribution into this cell membrane fraction in both WT and MACF1 KO mice correlated strikingly with the level of contractile dysfunction (r(2) = 0.786, p<.001). MACF1 disruption also resulted in reduction of membrane caveolin 3 levels, and increased levels of membrane PKCα and β1 integrin after TAC, suggesting MACF1 function is important for spatial regulation of several physiologically relevant signaling proteins during hypertrophy. Together, these data identify for the first time, a role for MACF1 in cardiomyocyte microtubule distribution and in adaptation to hemodynamic overload.

Combinatorial therapy of exercise-preconditioning and nanocurcumin formulation supplementation improves cardiac adaptation under hypobaric hypoxia.

PubMed

Nehra, Sarita; Bhardwaj, Varun; Bansal, Anju; Saraswat, Deepika

2017-09-26

Chronic hypobaric hypoxia (cHH) mediated cardiac insufficiencies are associated with pathological damage. Sustained redox stress and work load are major causative agents of cardiac insufficiencies under cHH. Despite the advancements made in pharmacological (anti-oxidants, vasodilators) and non-pharmacological therapeutics (acclimatization strategies and schedules), only partial success has been achieved in improving cardiac acclimatization to cHH. This necessitates the need for potent combinatorial therapies to improve cardiac acclimatization at high altitudes. We hypothesize that a combinatorial therapy comprising preconditioning to mild aerobic treadmill exercise and supplementation with nanocurcumin formulation (NCF) consisting of nanocurcumin (NC) and pyrroloquinoline quinone (PQQ) might improve cardiac adaptation at high altitudes. Adult Sprague-Dawley rats pre-conditioned to treadmill exercise and supplemented with NCF were exposed to cHH (7620 m altitude corresponding to pO2~8% at 28±2°C, relative humidity 55%±1%) for 3 weeks. The rat hearts were analyzed for changes in markers of oxidative stress (free radical leakage, lipid peroxidation, manganese-superoxide dismutase [MnSOD] activity), cardiac injury (circulating cardiac troponin I [TnI] and T [cTnT], myocardial creatine kinase [CK-MB]), metabolic damage (lactate dehydrogenase [LDH] and acetyl-coenzyme A levels, lactate and pyruvate levels) and bio-energetic insufficiency (ATP, p-AMPKα). Significant modulations (p≤0.05) in cardiac redox status, metabolic damage, cardiac injury and bio-energetics were observed in rats receiving both NCF supplementation and treadmill exercise-preconditioning compared with rats receiving only one of the treatments. The combinatorial therapeutic strategy showed a tremendous improvement in cardiac acclimatization to cHH compared to either exercise-preconditioning or NCF supplementation alone which was evident from the effective modulation in redox, metabolic, contractile and bio-energetic homeostasis.

Patient-Adaptive Reconstruction and Acquisition in Dynamic Imaging with Sensitivity Encoding (PARADISE)

PubMed Central

Sharif, Behzad; Derbyshire, J. Andrew; Faranesh, Anthony Z.; Bresler, Yoram

2010-01-01

MR imaging of the human heart without explicit cardiac synchronization promises to extend the applicability of cardiac MR to a larger patient population and potentially expand its diagnostic capabilities. However, conventional non-gated imaging techniques typically suffer from low image quality or inadequate spatio-temporal resolution and fidelity. Patient-Adaptive Reconstruction and Acquisition in Dynamic Imaging with Sensitivity Encoding (PARADISE) is a highly-accelerated non-gated dynamic imaging method that enables artifact-free imaging with high spatio-temporal resolutions by utilizing novel computational techniques to optimize the imaging process. In addition to using parallel imaging, the method gains acceleration from a physiologically-driven spatio-temporal support model; hence, it is doubly accelerated. The support model is patient-adaptive, i.e., its geometry depends on dynamics of the imaged slice, e.g., subject’s heart-rate and heart location within the slice. The proposed method is also doubly adaptive as it adapts both the acquisition and reconstruction schemes. Based on the theory of time-sequential sampling, the proposed framework explicitly accounts for speed limitations of gradient encoding and provides performance guarantees on achievable image quality. The presented in-vivo results demonstrate the effectiveness and feasibility of the PARADISE method for high resolution non-gated cardiac MRI during a short breath-hold. PMID:20665794

IN VITRO EFFECTS OF CHLORPYRIFOS, PARATHION, METHYL PARATHION AND THEIR OXONS ON CARDIAC MUSCARINIC RECEPTOR BINDING IN NEONATAL AND ADULT RATS. (R825811)

EPA Science Inventory

Organophosphorus insecticides elicit toxicity by inhibiting acetylcholinesterase. Young animals are generally more sensitive than adults to these toxicants. A number of studies reported that some organophosphorus agents also bind directly to muscarinic receptors, in particular...

Cardiac myosin binding protein C regulates postnatal myocyte cytokinesis

PubMed Central

Jiang, Jianming; Burgon, Patrick G.; Wakimoto, Hiroko; Onoue, Kenji; Gorham, Joshua M.; O’Meara, Caitlin C.; Fomovsky, Gregory; McConnell, Bradley K.; Lee, Richard T.; Seidman, J. G.; Seidman, Christine E.

2015-01-01

Homozygous cardiac myosin binding protein C-deficient (Mybpct/t) mice develop dramatic cardiac dilation shortly after birth; heart size increases almost twofold. We have investigated the mechanism of cardiac enlargement in these hearts. Throughout embryogenesis myocytes undergo cell division while maintaining the capacity to pump blood by rapidly disassembling and reforming myofibrillar components of the sarcomere throughout cell cycle progression. Shortly after birth, myocyte cell division ceases. Cardiac MYBPC is a thick filament protein that regulates sarcomere organization and rigidity. We demonstrate that many Mybpct/t myocytes undergo an additional round of cell division within 10 d postbirth compared with their wild-type counterparts, leading to increased numbers of mononuclear myocytes. Short-hairpin RNA knockdown of Mybpc3 mRNA in wild-type mice similarly extended the postnatal window of myocyte proliferation. However, adult Mybpct/t myocytes are unable to fully regenerate the myocardium after injury. MYBPC has unexpected inhibitory functions during postnatal myocyte cytokinesis and cell cycle progression. We suggest that human patients with homozygous MYBPC3-null mutations develop dilated cardiomyopathy, coupled with myocyte hyperplasia (increased cell number), as observed in Mybpct/t mice. Human patients, with heterozygous truncating MYBPC3 mutations, like mice with similar mutations, have hypertrophic cardiomyopathy. However, the mechanism leading to hypertrophic cardiomyopathy in heterozygous MYBPC3+/− individuals is myocyte hypertrophy (increased cell size), whereas the mechanism leading to cardiac dilation in homozygous Mybpc3−/− mice is primarily myocyte hyperplasia. PMID:26153423

Cardiology needs good planning for the future.

PubMed

Goodroe, J H; Hicks, K J

1990-08-01

In today's health care environment, hospitals have to develop strategies to maintain their market share, especially in cardiac services. The authors share generic strategies in cost leadership, product differentiation and technological leadership that can be adapted and implemented in cardiac centers.

The flexibility of two tropomyosin mutants, D175N and E180G, that cause hypertrophic cardiomyopathy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Xiaochuan; Suphamungmee, Worawit; Janco, Miro

2012-08-03

Highlights: Black-Right-Pointing-Pointer Well-known tropomyosin mutants, D175N and E180G are linked to cardiomyopathies. Black-Right-Pointing-Pointer The structural mechanics of D175N and E180G tropomyosins have been investigated. Black-Right-Pointing-Pointer D175N and E180G mutations increase both local and global tropomyosin flexibility. Black-Right-Pointing-Pointer In muscle, this increased flexibility will enhance myosin interactions on actin. Black-Right-Pointing-Pointer Extra myosin interaction can alter cardiac Ca{sup 2+}-switching, leading to dysfunction. -- Abstract: Point mutations targeting muscle thin filament proteins are the cause of a number of cardiomyopathies. In many cases, biological effects of the mutations are well-documented, whereas their structural and mechanical impact on filament assembly and regulatory function ismore » lacking. In order to elucidate molecular defects leading to cardiac dysfunction, we have examined the structural mechanics of two tropomyosin mutants, E180G and D175N, which are associated with hypertrophic cardiomyopathy (HCM). Tropomyosin is an {alpha}-helical coiled-coil dimer which polymerizes end-to-end to create an elongated superhelix that wraps around F-actin filaments of muscle and non-muscle cells, thus modulating the binding of other actin-binding proteins. Here, we study how flexibility changes in the E180G and D175N mutants might affect tropomyosin binding and regulatory motion on F-actin. Electron microscopy and Molecular Dynamics simulations show that E180G and D175N mutations cause an increase in bending flexibility of tropomyosin both locally and globally. This excess flexibility is likely to increase accessibility of the myosin-binding sites on F-actin, thus destabilizing the low-Ca{sup 2+} relaxed-state of cardiac muscle. The resulting imbalance in the on-off switching mechanism of the mutants will shift the regulatory equilibrium towards Ca{sup 2+}-activation of cardiac muscle, as is observed in affected muscle, accompanied by enhanced systolic activity, diastolic dysfunction, and cardiac compensations associated with HCM and heart failure.« less

Cardiac hypertrophy induced by active Raf depends on Yorkie-mediated transcription

PubMed Central

Yu, Lin; Daniels, Joseph P.; Wu, Huihui; Wolf, Matthew J.

2015-01-01

Organ hypertrophy can result from enlargement of individual cells or from cell proliferation or both. Activating mutations in the serine-threonine kinase Raf cause cardiac hypertrophy and contribute to Noonan syndrome in humans. Cardiac-specific expression of activated Raf also causes hypertrophy in Drosophila melanogaster. We found that Yorkie (Yki), a transcriptional coactivator in the Hippo pathway that regulates organ size, is required for Raf-induced cardiac hypertrophy in flies. Although aberrant activation of Yki orthologs stimulates cardiac hyperplasia in mice, cardiac-specific expression of an activated mutant form of Yki in fruit flies caused cardiac hypertrophy without hyperplasia. Knockdown of Yki caused cardiac dilation without loss of cardiomyocytes and prevented Raf-induced cardiac hypertrophy. In flies, Yki-induced cardiac hypertrophy required the TEA domain–containing transcription factor Scalloped, and, in mammalian cells, expression of mouse RafL613V, an activated form of Raf with a Noonan syndrome mutation, increased Yki-induced Scalloped activity. Furthermore, overexpression of Tgi (a Tondu domain–containing Scalloped-binding corepressor) in the fly heart abrogated Yki- or Raf-induced cardiac hypertrophy. Thus, crosstalk between Raf and Yki occurs in the heart and can influence Raf-mediated cardiac hypertrophy. PMID:25650441

Molecular mechanisms underlying deoxy‐ADP.Pi activation of pre‐powerstroke myosin

PubMed Central

Nowakowski, Sarah G.

2017-01-01

Abstract Myosin activation is a viable approach to treat systolic heart failure. We previously demonstrated that striated muscle myosin is a promiscuous ATPase that can use most nucleoside triphosphates as energy substrates for contraction. When 2‐deoxy ATP (dATP) is used, it acts as a myosin activator, enhancing cross‐bridge binding and cycling. In vivo, we have demonstrated that elevated dATP levels increase basal cardiac function and rescues function of infarcted rodent and pig hearts. Here we investigate the molecular mechanism underlying this physiological effect. We show with molecular dynamics simulations that the binding of dADP.Pi (dATP hydrolysis products) to myosin alters the structure and dynamics of the nucleotide binding pocket, myosin cleft conformation, and actin binding sites, which collectively yield a myosin conformation that we predict favors weak, electrostatic binding to actin. In vitro motility assays at high ionic strength were conducted to test this prediction and we found that dATP increased motility. These results highlight alterations to myosin that enhance cross‐bridge formation and reveal a potential mechanism that may underlie dATP‐induced improvements in cardiac function. PMID:28097776

Development of a positive psychology intervention for patients with acute cardiovascular disease

PubMed Central

Huffman, Jeff C.; Mastromauro, Carol A.; Boehm, Julia K.; Seabrook, Rita; Fricchione, Gregory L.; Denninger, John W.; Lyubomirsky, Sonja

2011-01-01

The management of depression and other negative psychological states in cardiac patients has been a focus of multiple treatment trials, though such trials have not led to substantial improvements in cardiac outcomes. In contrast, there has been minimal focus on interventions to increase positive psychological states in cardiac patients, despite the fact that optimism and other positive states have been associated with superior cardiovascular outcomes. Our objective was to develop an 8-week, phone-based positive psychology intervention for patients hospitalized with acute cardiac disease (acute coronary syndrome or decompensated heart failure). Such an intervention would consist of positive psychology exercises adapted for this specific population, and it would need to be feasible for practitioners and patients in real-world settings. By adapting exercises that were previously validated in healthy individuals, we were able to generate a positive psychology telemedicine intervention for cardiac patients that focused on optimism, kindness, and gratitude. In addition, we successfully created a companion treatment manual for subjects to enhance the educational aspects of the intervention and facilitate completion of exercises. Finally, we successfully performed a small pilot trial of this intervention, and found that the positive psychology intervention appeared to be feasible and well-accepted in a cohort of patients with acute cardiac illness. Future studies should further develop this promising intervention and examine its impact on psychological and medical outcomes in this vulnerable population of cardiac patients. PMID:23825741

Development of a positive psychology intervention for patients with acute cardiovascular disease.

PubMed

Huffman, Jeff C; Mastromauro, Carol A; Boehm, Julia K; Seabrook, Rita; Fricchione, Gregory L; Denninger, John W; Lyubomirsky, Sonja

2011-09-29

The management of depression and other negative psychological states in cardiac patients has been a focus of multiple treatment trials, though such trials have not led to substantial improvements in cardiac outcomes. In contrast, there has been minimal focus on interventions to increase positive psychological states in cardiac patients, despite the fact that optimism and other positive states have been associated with superior cardiovascular outcomes. Our objective was to develop an 8-week, phone-based positive psychology intervention for patients hospitalized with acute cardiac disease (acute coronary syndrome or decompensated heart failure). Such an intervention would consist of positive psychology exercises adapted for this specific population, and it would need to be feasible for practitioners and patients in real-world settings. By adapting exercises that were previously validated in healthy individuals, we were able to generate a positive psychology telemedicine intervention for cardiac patients that focused on optimism, kindness, and gratitude. In addition, we successfully created a companion treatment manual for subjects to enhance the educational aspects of the intervention and facilitate completion of exercises. Finally, we successfully performed a small pilot trial of this intervention, and found that the positive psychology intervention appeared to be feasible and well-accepted in a cohort of patients with acute cardiac illness. Future studies should further develop this promising intervention and examine its impact on psychological and medical outcomes in this vulnerable population of cardiac patients.

Predicting Length of Stay in Intensive Care Units after Cardiac Surgery: Comparison of Artificial Neural Networks and Adaptive Neuro-fuzzy System.

PubMed

Maharlou, Hamidreza; Niakan Kalhori, Sharareh R; Shahbazi, Shahrbanoo; Ravangard, Ramin

2018-04-01

Accurate prediction of patients' length of stay is highly important. This study compared the performance of artificial neural network and adaptive neuro-fuzzy system algorithms to predict patients' length of stay in intensive care units (ICU) after cardiac surgery. A cross-sectional, analytical, and applied study was conducted. The required data were collected from 311 cardiac patients admitted to intensive care units after surgery at three hospitals of Shiraz, Iran, through a non-random convenience sampling method during the second quarter of 2016. Following the initial processing of influential factors, models were created and evaluated. The results showed that the adaptive neuro-fuzzy algorithm (with mean squared error [MSE] = 7 and R = 0.88) resulted in the creation of a more precise model than the artificial neural network (with MSE = 21 and R = 0.60). The adaptive neuro-fuzzy algorithm produces a more accurate model as it applies both the capabilities of a neural network architecture and experts' knowledge as a hybrid algorithm. It identifies nonlinear components, yielding remarkable results for prediction the length of stay, which is a useful calculation output to support ICU management, enabling higher quality of administration and cost reduction.

Heat shock transcription factor 1 protects against pressure overload-induced cardiac fibrosis via Smad3.

PubMed

Zhou, Ning; Ye, Yong; Wang, Xingxu; Ma, Ben; Wu, Jian; Li, Lei; Wang, Lin; Wang, Dao Wen; Zou, Yunzeng

2017-04-01

Fibrotic cardiac muscle exhibits high stiffness and low compliance which are major risk factors of heart failure. Although heat shock transcription factor 1 (HSF1) was identified as an intrinsic cardioprotective factor, the role that HSF1 plays in cardiac fibrosis remains unclear. Our study aims to investigate the role of HSF1 in pressure overload-induced cardiac fibrosis and the underlying mechanism. HSF1 phosphorylation was significantly downregulated in transverse aortic constriction (TAC)-treated mouse hearts and mechanically stretched cardiac fibroblasts (cFBs). HSF1 transgenic (TG) mice, HSF1 deficient heterozygote (KO) mice, and their wild-type littermates were subjected to sham or TAC surgery for 4 weeks. HSF1 overexpression significantly attenuated pressure overload-induced cardiac fibrosis and dysfunction. Conversely, HSF1 KO mice showed deteriorated fibrotic response and cardiac dysfunction upon TAC. Moreover, we uncovered that overexpression of HSF1 protected against fibrotic response of cFBs to pressure overload. Mechanistically, we observed that the phosphorylation and the nuclear distribution of the Smad family member 3 (Smad3) were significantly decreased in HSF1-overexpressing mouse hearts, while being greatly increased in HSF1 KO mouse hearts upon TAC, compared to the control hearts, respectively. Similar alteration of Smad3 phosphorylation and nuclear distribution were found in isolated mouse cardiac fibroblasts and mechanically stretched cFBs. Constitutively active Smad3 blocked the anti-fibrotic effect of HSF1 in cFBs. Furthermore, we found a direct binding of phosphorylated HSF1 and Smad3, which can be suppressed by mechanical stress. In conclusion, the present study demonstrated for the first time that HSF1 acts as a novel negative regulator of cardiac fibrosis by blocking Smad3 activation. HSF1 activity is decreased in fibrotic hearts. HSF1 overexpression attenuates pressure overload-induced cardiac fibrosis and dysfunction. Deficiency of HSF1 deteriorates fibrotic response and cardiac dysfunction upon TAC. HSF1 inhibits phosphorylation and nuclear distribution of Smad3 via direct binding to Smad3. Active Smad3 blocks the anti-fibrotic effect of HSF1.

Circuit weight training and cardiac morphology: a trial with magnetic resonance imaging.

PubMed

Camargo, M D; Stein, R; Ribeiro, J P; Schvartzman, P R; Rizzatti, M O; Schaan, B D

2008-02-01

Aerobic training (AT) and circuit weight training (CWT) improve peak oxygen uptake (VO(2)peak). During CWT the circulatory system is exposed to higher pressure, which could induce left ventricle morphological adaptations, possibly distinct from those derived from aerobic training. To compare the effects of aerobic training and CWT upon morphological and functional cardiac adaptations detected by magnetic resonance imaging. Twenty healthy sedentary individuals were randomly assigned to participate in a 12-week programme of aerobic training (n = 6), CWR (n = 7) or no intervention (n = 7, controls). Training programmes consisted of 36 sessions, 35 min each, 3 times per week, at 70% of maximal heart rate, and CWT included series of resistance exercises performed at 60% of 1 maximal repetition. Cardiopulmonary exercise testing and cardiac magnetic resonance imaging were performed before and after the intervention. There was a similar improvement in VO(2)peak following aerobic training (mean (SD) increment: 12 (4)%) and CWT (12 (4)%), while there was no change in the control group. Aerobic training (12 (6)%) and CWT (16 (5)%) improved strength in the lower limbs, and only CWT resulted in improvement of 13 (4)% in the strength of the upper limbs. However, there were no detectable changes in left ventricular mass, end-diastolic volume, stroke volume or ejection fraction. In previously sedentary individuals, short-term CWT and aerobic training induce similar improvement in functional capacity without any adaptation in cardiac morphology detectable by cardiac magnetic resonance imaging.

Molecular Basis of Cardiac Delayed Rectifier Potassium Channel Function and Pharmacology.

PubMed

Wu, Wei; Sanguinetti, Michael C

2016-06-01

Human cardiomyocytes express 3 distinct types of delayed rectifier potassium channels. Human ether-a-go-go-related gene (hERG) channels conduct the rapidly activating current IKr; KCNQ1/KCNE1 channels conduct the slowly activating current IKs; and Kv1.5 channels conduct an ultrarapid activating current IKur. Here the authors provide a general overview of the mechanistic and structural basis of ion selectivity, gating, and pharmacology of the 3 types of cardiac delayed rectifier potassium ion channels. Most blockers bind to S6 residues that line the central cavity of the channel, whereas activators interact with the channel at 4 symmetric binding sites outside the cavity. Copyright © 2016 Elsevier Inc. All rights reserved.

Cardiac tissue enriched factors serum response factor and GATA-4 are mutual coregulators

NASA Technical Reports Server (NTRS)

Belaguli, N. S.; Sepulveda, J. L.; Nigam, V.; Charron, F.; Nemer, M.; Schwartz, R. J.

2000-01-01

Combinatorial interaction among cardiac tissue-restricted enriched transcription factors may facilitate the expression of cardiac tissue-restricted genes. Here we show that the MADS box factor serum response factor (SRF) cooperates with the zinc finger protein GATA-4 to synergistically activate numerous myogenic and nonmyogenic serum response element (SRE)-dependent promoters in CV1 fibroblasts. In the absence of GATA binding sites, synergistic activation depends on binding of SRF to the proximal CArG box sequence in the cardiac and skeletal alpha-actin promoter. GATA-4's C-terminal activation domain is obligatory for synergistic coactivation with SRF, and its N-terminal domain and first zinc finger are inhibitory. SRF and GATA-4 physically associate both in vivo and in vitro through their MADS box and the second zinc finger domains as determined by protein A pullout assays and by in vivo one-hybrid transfection assays using Gal4 fusion proteins. Other cardiovascular tissue-restricted GATA factors, such as GATA-5 and GATA-6, were equivalent to GATA-4 in coactivating SRE-dependent targets. Thus, interaction between the MADS box and C4 zinc finger proteins, a novel regulatory paradigm, mediates activation of SRF-dependent gene expression.

Heart-type fatty acid binding protein (H-FABP) as a biomarker for acute myocardial injury and long-term post-ischemic prognosis.

PubMed

Ye, Xiao-Dong; He, Yi; Wang, Sheng; Wong, Gordon T; Irwin, Michael G; Xia, Zhengyuan

2018-05-17

Acute myocardial infarction (AMI) is a life-threatening event. Even with timely treatment, acute ischemic myocardial injury and ensuing ischemia reperfusion injury (IRI) can still be difficult issues to tackle. Apart from radiological and other auxiliary examinations, laboratory tests of applicable cardiac biomarkers are also necessary for early diagnosis and close monitoring of this disorder. Heart-type fatty acid binding protein (H-FABP), which mainly exists inside cardiomyocytes, has recently emerged as a potentially promising biomarker for myocardial injury. In this review we discuss the sensitivity and specificity of H-FABP in the assessment of myocardial injury and IRI, especially in the early stage, and its long-term prognostic value in comparison with other commonly used cardiac biomarkers, including myoglobin (Mb), cardiac troponin I (cTnI), creatine kinase MB (CK-MB), C-reactive protein (CRP), glycogen phosphorylase isoenzyme BB (GPBB), and high-sensitivity cardiac troponin T (hs-cTnT). The potential and value of combined application of H-FABP with other biomarkers are also discussed. Finally, the prospect of H-FABP is summarized; several technical issues are discussed to facilitate wider application of H-FABP in clinical practice.

Fluorescent Protein-Based Ca2+ Sensor Reveals Global, Divalent Cation-Dependent Conformational Changes in Cardiac Troponin C.

PubMed

Badr, Myriam A; Pinto, Jose R; Davidson, Michael W; Chase, P Bryant

2016-01-01

Cardiac troponin C (cTnC) is a key effector in cardiac muscle excitation-contraction coupling as the Ca2+ sensing subunit responsible for controlling contraction. In this study, we generated several FRET sensors for divalent cations based on cTnC flanked by a donor fluorescent protein (CFP) and an acceptor fluorescent protein (YFP). The sensors report Ca2+ and Mg2+ binding, and relay global structural information about the structural relationship between cTnC's N- and C-domains. The sensors were first characterized using end point titrations to decipher the response to Ca2+ binding in the presence or absence of Mg2+. The sensor that exhibited the largest responses in end point titrations, CTV-TnC, (Cerulean, TnC, and Venus) was characterized more extensively. Most of the divalent cation-dependent FRET signal originates from the high affinity C-terminal EF hands. CTV-TnC reconstitutes into skinned fiber preparations indicating proper assembly of troponin complex, with only ~0.2 pCa unit rightward shift of Ca2+-sensitive force development compared to WT-cTnC. Affinity of CTV-TnC for divalent cations is in agreement with known values for WT-cTnC. Analytical ultracentrifugation indicates that CTV-TnC undergoes compaction as divalent cations bind. C-terminal sites induce ion-specific (Ca2+ versus Mg2+) conformational changes in cTnC. Our data also provide support for the presence of additional, non-EF-hand sites on cTnC for Mg2+ binding. In conclusion, we successfully generated a novel FRET-Ca2+ sensor based on full length cTnC with a variety of cellular applications. Our sensor reveals global structural information about cTnC upon divalent cation binding.

Myofilament Calcium Sensitivity: Mechanistic Insight into TnI Ser-23/24 and Ser-150 Phosphorylation Integration

PubMed Central

Salhi, Hussam E.; Hassel, Nathan C.; Siddiqui, Jalal K.; Brundage, Elizabeth A.; Ziolo, Mark T.; Janssen, Paul M. L.; Davis, Jonathan P.; Biesiadecki, Brandon J.

2016-01-01

Troponin I (TnI) is a major regulator of cardiac muscle contraction and relaxation. During physiological and pathological stress, TnI is differentially phosphorylated at multiple residues through different signaling pathways to match cardiac function to demand. The combination of these TnI phosphorylations can exhibit an expected or unexpected functional integration, whereby the function of two phosphorylations are different than that predicted from the combined function of each individual phosphorylation alone. We have shown that TnI Ser-23/24 and Ser-150 phosphorylation exhibit functional integration and are simultaneously increased in response to cardiac stress. In the current study, we investigated the functional integration of TnI Ser-23/24 and Ser-150 to alter cardiac contraction. We hypothesized that Ser-23/24 and Ser-150 phosphorylation each utilize distinct molecular mechanisms to alter the TnI binding affinity within the thin filament. Mathematical modeling predicts that Ser-23/24 and Ser-150 phosphorylation affect different TnI affinities within the thin filament to distinctly alter the Ca2+-binding properties of troponin. Protein binding experiments validate this assertion by demonstrating pseudo-phosphorylated Ser-150 decreases the affinity of isolated TnI for actin, whereas Ser-23/24 pseudo-phosphorylation is not different from unphosphorylated. Thus, our data supports that TnI Ser-23/24 affects TnI-TnC binding, while Ser-150 phosphorylation alters TnI-actin binding. By measuring force development in troponin-exchanged skinned myocytes, we demonstrate that the Ca2+ sensitivity of force is directly related to the amount of phosphate present on TnI. Furthermore, we demonstrate that Ser-150 pseudo-phosphorylation blunts Ser-23/24-mediated decreased Ca2+-sensitive force development whether on the same or different TnI molecule. Therefore, TnI phosphorylations can integrate across troponins along the myofilament. These data demonstrate that TnI Ser-23/24 and Ser-150 phosphorylation regulates muscle contraction in part by modulating different TnI interactions in the thin filament and it is the combination of these differential mechanisms that provides understanding of their functional integration. PMID:28018230

Computational Models for Understanding of Structure, Function and Pharmacology of the Cardiac Potassium Channel Kv11.1 (hERG).

PubMed

Wacker, Soren; Noskov, Sergei Yu; Perissinotti, Laura L

2017-01-01

The rapid delayed rectifier current IKr is one of the major K+ currents involved in repolarization of the human cardiac action potential. Various inherited or drug-induced forms of the long QT syndrome (LQTS) in humans are linked to functional and structural modifications in the IKr conducting channels. IKr is carried by the potassium channel Kv11.1 encoded by the gene KCNH2 (commonly referred to as human ether-a-go-go-related gene or hERG) [1, 2]. The first necessary step for predicting emergent drug effects on the heart is determining and modeling the binding thermodynamics and kinetics of primary and major off-target drug interactions with subcellular targets. The bulk of drugs that target hERG channels are known to have complex interactions at the atomic scale. Accordingly, one of the goals for this review is to provide comprehensive guide in the universe of computational models aiming to refine our understanding of structure-function relations in Kv11.1 and its isoforms. The special emphasis is placed on the mapping of drug binding sites and tentative mechanisms of channel inhibition and activation by drugs. An overview over recent structural models and mapping of binding sites for blockers and activators of IKr current along with the discussion on agreements and discrepancies among different models is presented. There is an apparent reciprocity or feedback loop between drug binding and action potential of the cardiac myocytes. Thus one has to connect drug binding to a particular receptor so that its functional consequences impact on the action potential duration. The natural pathway is to develop multi-scale models that connect between receptor and cellular scales. The potential for such multi-scale model development is discussed through the lens of common gating models. Accordingly, the second part of this review covers an ongoing development of the kinetic models of gating transitions and cardiac ion currents carried by hERG channels with and without drug bound. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Localization and functional consequences of a direct interaction between TRIOBP-1 and hERG proteins in the heart.

PubMed

Jones, David K; Johnson, Ashley C; Roti Roti, Elon C; Liu, Fang; Uelmen, Rebecca; Ayers, Rebecca A; Baczko, Istvan; Tester, David J; Ackerman, Michael J; Trudeau, Matthew C; Robertson, Gail A

2018-03-22

Reduced levels of the cardiac human (h)ERG ion channel protein and the corresponding repolarizing current I Kr can cause arrhythmia and sudden cardiac death, but the underlying cellular mechanisms controlling hERG surface expression are not well understood. Here, we identified TRIOBP-1, an F-actin-binding protein previously associated with actin polymerization, as a putative hERG-interacting protein in a yeast-two hybrid screen of a cardiac library. We corroborated this interaction by performing Förster resonance energy transfer (FRET) in HEK293 cells and co-immunoprecipitation in HEK293 cells and native cardiac tissue. TRIOBP-1 overexpression reduced hERG surface expression and current density, whereas reducing TRIOBP-1 expression via shRNA knockdown resulted in increased hERG protein levels. Immunolabeling in rat cardiomyocytes showed that native TRIOBP-1 colocalized predominantly with myosin-binding protein C and secondarily with rat ERG. In human stem cell-derived cardiomyocytes, TRIOBP-1 overexpression caused intracellular co-sequestration of hERG signal, reduced native I Kr and disrupted action potential repolarization. Ca 2+ currents were also somewhat reduced and cell capacitance was increased. These findings establish that TRIOBP-1 interacts directly with hERG and can affect protein levels, I Kr magnitude and cardiac membrane excitability. © 2018. Published by The Company of Biologists Ltd.

Erbin is a negative modulator of cardiac hypertrophy

PubMed Central

Rachmin, Inbal; Tshori, Sagi; Smith, Yoav; Oppenheim, Amit; Marchetto, Sylvie; Kay, Gillian; Foo, Roger S.-Y.; Dagan, Noa; Golomb, Eliahu; Gilon, Dan; Borg, Jean-Paul; Razin, Ehud

2014-01-01

ErbB2 interacting protein (Erbin) is a widely expressed protein and participates in inhibition of several intracellular signaling pathways. Its mRNA has been found to be present in relatively high levels in the heart. However, its physiological role in the heart has not been explored. In the present work, we elucidated the role of Erbin in cardiac hypertrophy. Cardiac hypertrophy was induced in mice either by isoproterenol administration or by aortic constriction. The level of Erbin was significantly decreased in both models. Erbin−/− mice rapidly develop decompensated cardiac hypertrophy, and following severe pressure overload all Erbin−/− mice died from heart failure. Down-regulation of Erbin expression was also observed in biopsies derived from human failing hearts. It is known that Erbin inhibits Ras-mediated activation of the extracellular signal-regulated kinase (ERK) by binding to Soc-2 suppressor of clear homolog (Shoc2). Our data clearly show that ERK phosphorylation is enhanced in the heart tissues of Erbin−/− mice. Furthermore, we clearly demonstrate here that Erbin associates with Shoc2 in both whole hearts and in cardiomyocytes, and that in the absence of Erbin, Raf is phosphorylated and binds Shoc2, resulting in ERK phosphorylation. In conclusion, Erbin is an inhibitor of pathological cardiac hypertrophy, and this inhibition is mediated, at least in part, by modulating ERK signaling. PMID:24711380

Understanding the in vivo uptake kinetics of a phosphatidylethanolamine-binding agent 99mTc-Duramycin

PubMed Central

Audi, Said; Li, Zhixin; Capacete, Joseph; Liu, Yu; Fang, Wei; Shu, Laura G.; Zhao, Ming

2013-01-01

Introduction 99mTc-Duramycin is a peptide-based molecular probe that binds specifically to phosphatidylethanolamine (PE). The goal was to characterize the kinetics of molecular interactions between 99mTc-Duramycin and the target tissue. Methods High level of accessible PE is induced in cardiac tissues by myocardial ischemia (30 min) and reperfusion (120 min) in Sprague Dawley rats. Target binding and biodistribution of 99mTc-duramycin was captured using SPECT/CT. To quantify the binding kinetics, the presence of radioactivity in ischemic versus normal cardiac tissues was measured by gamma counting at 3, 10, 20, 60 and 180 min after injection. A partially inactivated form of 99mTc-Duramycin was analyzed in the same fashion. A compartment model was developed to quantify the uptake kinetics of 99mTc-Duramycin in normal and ischemic myocardial tissue. Results 99mTc-duramycin binds avidly to the damaged tissue with a high target-to-background radio. Compartment modeling shows that accessibility of binding sites in myocardial tissue to 99mTc-Duramycin is not a limiting factor and the rate constant of target binding in the target tissue is at 2.2 ml/nmol/min/g. The number of available binding sites for 99mTc-Duramycin in ischemic myocardium was estimated at 0.14 nmol/g. Covalent modification of D15 resulted in a 9 fold reduction in binding affinity. Conclusion 99mTc-Duramycin accumulates avidly in target tissues in a PE-dependent fashion. Model results reflect an efficient uptake mechanism, consistent with the low molecular weight of the radiopharmaceutical and the relatively high density of available binding sites. These data help better define the imaging utilities of 99mTc-Duramycin as a novel PE-binding agent. PMID:22534031

Trigger learning and ECG parameter customization for remote cardiac clinical care information system.

PubMed

Bashir, Mohamed Ezzeldin A; Lee, Dong Gyu; Li, Meijing; Bae, Jang-Whan; Shon, Ho Sun; Cho, Myung Chan; Ryu, Keun Ho

2012-07-01

Coronary heart disease is being identified as the largest single cause of death along the world. The aim of a cardiac clinical information system is to achieve the best possible diagnosis of cardiac arrhythmias by electronic data processing. Cardiac information system that is designed to offer remote monitoring of patient who needed continues follow up is demanding. However, intra- and interpatient electrocardiogram (ECG) morphological descriptors are varying through the time as well as the computational limits pose significant challenges for practical implementations. The former requires that the classification model be adjusted continuously, and the latter requires a reduction in the number and types of ECG features, and thus, the computational burden, necessary to classify different arrhythmias. We propose the use of adaptive learning to automatically train the classifier on up-to-date ECG data, and employ adaptive feature selection to define unique feature subsets pertinent to different types of arrhythmia. Experimental results show that this hybrid technique outperforms conventional approaches and is, therefore, a promising new intelligent diagnostic tool.

Modulation of Hypercholesterolemia-Induced Oxidative/Nitrative Stress in the Heart

PubMed Central

Sárközy, Márta; Pipicz, Márton; Dux, László; Csont, Tamás

2016-01-01

Hypercholesterolemia is a frequent metabolic disorder associated with increased risk for cardiovascular morbidity and mortality. In addition to its well-known proatherogenic effect, hypercholesterolemia may exert direct effects on the myocardium resulting in contractile dysfunction, aggravated ischemia/reperfusion injury, and diminished stress adaptation. Both preclinical and clinical studies suggested that elevated oxidative and/or nitrative stress plays a key role in cardiac complications induced by hypercholesterolemia. Therefore, modulation of hypercholesterolemia-induced myocardial oxidative/nitrative stress is a feasible approach to prevent or treat deleterious cardiac consequences. In this review, we discuss the effects of various pharmaceuticals, nutraceuticals, some novel potential pharmacological approaches, and physical exercise on hypercholesterolemia-induced oxidative/nitrative stress and subsequent cardiac dysfunction as well as impaired ischemic stress adaptation of the heart in hypercholesterolemia. PMID:26788247

Postural Regulation of Muscle Sympathetic Nerve Activity Before and After Simulated and Actual Microgravity Deconditioning

NASA Technical Reports Server (NTRS)

Pawelczyk, J. A.; Levine, B. D.

1999-01-01

The etiology of orthostatic intolerance after spaceflight is multifaceted. Morphological adaptations, in particular cardiac atrophy, are likely to magnify the decrease in stroke volume that occurs with reductions in cardiac filling pressure when standing. Neural adaptations may be inferred as well, as reductions in carotid-cardiac baroreflex responsiveness have been reported following bedrest deconditioning and spaceflight. Neural control of vascular resistance has not been studied directly when orthostatic intolerance is florid in the hours following spaceflight. However, the increases in systemic vascular resistance and plasma catecholamines during orthostatic stress are inappropriately low in orthostatically intolerant subjects following spaceflight, suggesting that deficits in the regulation of vascular resistance may be associated with hypoadrenergic function. The studies described in this abstract were designed to test this hypothesis.

Label-Free Detection of Cardiac Troponin-I Using Carbon Nanofiber Based Nanoelectrode Arrays

NASA Technical Reports Server (NTRS)

Periyakaruppan, Adaikkappan; Koehne, Jessica Erin; Gandhiraman, Ram P.; Meyyappan, M.

2013-01-01

A sensor platform based on vertically aligned carbon nanofibers (CNFs) has been developed. Their inherent nanometer scale, high conductivity, wide potential window, good biocompatibility and well-defined surface chemistry make them ideal candidates as biosensor electrodes. A carbon nanofiber (CNF) multiplexed array has been fabricated with 9 sensing pads, each containing 40,000 carbon nanofibers as nanoelectrodes. Here, we report the use of vertically aligned CNF nanoelectrodes for the detection of cardiac Troponin-I for the early diagnosis of myocardial infarction. Antibody, antitroponin, probe immobilization and subsequent binding to human cardiac troponin-I were characterized using electrochemical impedance spectroscopy and cyclic voltammetry techniques. Each step of the modification process resulted in changes in electrical capacitance or resistance to charge transfer due to the changes at the electrode surface upon antibody immobilization and binding to the specific antigen. This sensor demonstrates high sensitivity, down to 0.2 ng/mL, and good selectivity making this platform a good candidate for early stage diagnosis of myocardial infarction.

Calmodulin Mutations Associated with Recurrent Cardiac Arrest in Infants

PubMed Central

Crotti, Lia; Johnson, Christopher N.; Graf, Elisabeth; De Ferrari, Gaetano M.; Cuneo, Bettina F.; Ovadia, Marc; Papagiannis, John; Feldkamp, Michael D.; Rathi, Subodh G.; Kunic, Jennifer D.; Pedrazzini, Matteo; Wieland, Thomas; Lichtner, Peter; Beckmann, Britt-Maria; Clark, Travis; Shaffer, Christian; Benson, D. Woodrow; Kääb, Stefan; Meitinger, Thomas; Strom, Tim M.; Chazin, Walter J.; Schwartz, Peter J.; George, Alfred L.

2013-01-01

Background Life-threatening disorders of heart rhythm may arise during infancy and can result in the sudden and tragic death of a child. We performed exome sequencing on two unrelated infants presenting with recurrent cardiac arrest to discover a genetic cause. Methods and Results We ascertained two unrelated infants (probands) with recurrent cardiac arrest and dramatically prolonged QTc interval who were both born to healthy parents. The two parent-child trios were investigated using exome sequencing to search for de novo genetic variants. We then performed follow-up candidate gene screening on an independent cohort of 82 subjects with congenital long-QT syndrome without an identified genetic cause. Biochemical studies were performed to determine the functional consequences of mutations discovered in two genes encoding calmodulin. We discovered three heterozygous de novo mutations in either CALM1 or CALM2, two of the three human genes encoding calmodulin, in the two probands and in two additional subjects with recurrent cardiac arrest. All mutation carriers were infants who exhibited life-threatening ventricular arrhythmias combined variably with epilepsy and delayed neurodevelopment. Mutations altered residues in or adjacent to critical calcium binding loops in the calmodulin carboxyl-terminal domain. Recombinant mutant calmodulins exhibited several fold reductions in calcium binding affinity. Conclusions Human calmodulin mutations disrupt calcium ion binding to the protein and are associated with a life-threatening condition in early infancy. Defects in calmodulin function will disrupt important calcium signaling events in heart affecting membrane ion channels, a plausible molecular mechanism for potentially deadly disturbances in heart rhythm during infancy. PMID:23388215

Downregulation of cardiac guanosine 5'-triphosphate-binding proteins in right atrium and left ventricle in pacing-induced congestive heart failure.

PubMed Central

Roth, D A; Urasawa, K; Helmer, G A; Hammond, H K

1993-01-01

The extent to which congestive heart failure (CHF) is dependent upon increased levels of the cardiac inhibitory GTP-binding protein (Gi), and the impact of CHF on the cardiac stimulatory GTP-binding protein (Gs) and mechanisms by which Gs may change remain unexplored. We have addressed these unsettled issues using pacing-induced CHF in pigs to examine physiological, biochemical, and molecular features of the right atrium (RA) and left ventricle (LV). CHF was associated with an 85 +/- 20% decrease in LV segment shortening (P < 0.001) and a 3.5-fold increase (P = 0.006) in the ED50 for isoproterenol-stimulated heart rate responsiveness. Myocardial beta-adrenergic receptor number was decreased 54% in RA (P = 0.004) and 57% in LV (P < 0.001), and multiple measures of adenylyl cyclase activity were depressed 49 +/- 8% in RA (P < 0.005), and 44 +/- 9% in LV (P < 0.001). Quantitative immunoblotting established that Gi and Gs were decreased in RA (Gi: 59% reduction; P < 0.0001; Gs: 28% reduction; P < 0.007) and LV (Gi: 35% reduction; P < 0.008; Gs: 28% reduction; P < 0.01) after onset of CHF. Reduced levels of Gi and Gs were confirmed by ADP ribosylation studies, and diminished function of Gs was established in reconstitution studies. Steady state levels for Gs alpha mRNA were increased in RA and unchanged in LV, and significantly more GS alpha was found in the supernatant (presumably cytosolic) fraction in RA and LV membrane homogenates after CHF, suggesting that increased Gs degradation, rather than decreased Gs synthesis, is the mechanism by which Gs is downregulated. We conclude that cardiac Gi content poorly predicts adrenergic responsiveness or contractile function, that decreased Gs is caused by increased degradation rather than decreased synthesis, and that alterations in beta-adrenergic receptors, adenylyl cyclase, and GTP-binding proteins are uniform in RA and LV in this model of congestive heart failure. Images PMID:8383705

Binding of FUN14 Domain Containing 1 With Inositol 1,4,5-Trisphosphate Receptor in Mitochondria-Associated Endoplasmic Reticulum Membranes Maintains Mitochondrial Dynamics and Function in Hearts in Vivo.

PubMed

Wu, Shengnan; Lu, Qiulun; Wang, Qilong; Ding, Ye; Ma, Zejun; Mao, Xiaoxiang; Huang, Kai; Xie, Zhonglin; Zou, Ming-Hui

2017-12-05

FUN14 domain containing 1 (FUNDC1) is a highly conserved outer mitochondrial membrane protein. The aim of this study is to examine whether FUNDC1 modulates the mitochondria-associated endoplasmic reticulum (ER) membranes (MAMs), mitochondrial morphology, and function in cardiomyocytes and intact hearts. The impacts of FUNDC1 on MAMs formation and cardiac functions were studied in mouse neonatal cardiomyocytes, in mice with cardiomyocyte-specific Fundc1 gene knockout ( Fundc1 f/Y /Cre αMyHC+/- ), and in the cardiac tissues of the patients with heart failure. In mouse neonatal cardiomyocytes and intact hearts, FUNDC1 was localized in MAMs by binding to ER-resided inositol 1,4,5-trisphosphate type 2 receptor (IP 3 R2). Fundc1 ablation disrupted MAMs and reduced the levels of IP 3 R2 and Ca 2+ in both mitochondria and cytosol, whereas overexpression of Fundc1 increased the levels of IP 3 R2 and Ca 2+ in both mitochondria and cytosol. Consistently, Fundc1 ablation increased Ca 2+ levels in ER, whereas Fundc1 overexpression lowered ER Ca 2+ levels. Further, Fundc1 ablation in cardiomyocytes elongated mitochondria and compromised mitochondrial functions. Mechanistically, we found that Fundc1 ablation-induced reduction of intracellular Ca 2+ levels suppressed mitochondrial fission 1 protein ( Fis1 ) expression and mitochondrial fission by reducing the binding of the cAMP response element binding protein (CREB) in the Fis1 promoter. Fundc1 f/Y /Cre αMyHC+/- mice but not their littermate control mice ( Fundc1 wt/Y /Cre αMyHC+/- ) exhibited cardiac dysfunction. The ligation of the left ventricle artery of Fundc1 f/Y /Cre αMyHC+/- mice caused more severe cardiac dysfunction than those in sham-treated Fundc1 f/Y /Cre αMyHC+/- mice. Finally, we found that the FUNDC1/MAMs/CREB/Fis1 signaling axis was significantly suppressed in patients with heart failure. We conclude that FUNDC1 binds to IP 3 R2 to modulate ER Ca 2+ release into mitochondria and cytosol. Further, a disruption of the FUNDC1 and IP 3 R2 interaction lowers the levels of Ca 2+ in mitochondria and cytosol, both of which instigate aberrant mitochondrial fission, mitochondrial dysfunction, cardiac dysfunction, and heart failure. © 2017 American Heart Association, Inc.

A cardiac pathway of cyclic GMP-independent signaling of guanylyl cyclase A, the receptor for atrial natriuretic peptide

PubMed Central

Klaiber, Michael; Dankworth, Beatrice; Kruse, Martin; Hartmann, Michael; Nikolaev, Viacheslav O.; Yang, Ruey-Bing; Völker, Katharina; Gaßner, Birgit; Oberwinkler, Heike; Feil, Robert; Freichel, Marc; Groschner, Klaus; Skryabin, Boris V.; Frantz, Stefan; Birnbaumer, Lutz; Pongs, Olaf; Kuhn, Michaela

2011-01-01

Cardiac atrial natriuretic peptide (ANP) regulates arterial blood pressure, moderates cardiomyocyte growth, and stimulates angiogenesis and metabolism. ANP binds to the transmembrane guanylyl cyclase (GC) receptor, GC-A, to exert its diverse functions. This process involves a cGMP-dependent signaling pathway preventing pathological [Ca2+]i increases in myocytes. In chronic cardiac hypertrophy, however, ANP levels are markedly increased and GC-A/cGMP responses to ANP are blunted due to receptor desensitization. Here we show that, in this situation, ANP binding to GC-A stimulates a unique cGMP-independent signaling pathway in cardiac myocytes, resulting in pathologically elevated intracellular Ca2+ levels. This pathway involves the activation of Ca2+‐permeable transient receptor potential canonical 3/6 (TRPC3/C6) cation channels by GC-A, which forms a stable complex with TRPC3/C6 channels. Our results indicate that the resulting cation influx activates voltage-dependent L-type Ca2+ channels and ultimately increases myocyte Ca2+i levels. These observations reveal a dual role of the ANP/GC-A–signaling pathway in the regulation of cardiac myocyte Ca2+i homeostasis. Under physiological conditions, activation of a cGMP-dependent pathway moderates the Ca2+i-enhancing action of hypertrophic factors such as angiotensin II. By contrast, a cGMP-independent pathway predominates under pathophysiological conditions when GC-A is desensitized by high ANP levels. The concomitant rise in [Ca2+]i might increase the propensity to cardiac hypertrophy and arrhythmias. PMID:22027011

Role of the immune system in cardiac tissue damage and repair following myocardial infarction.

PubMed

Saparov, Arman; Ogay, Vyacheslav; Nurgozhin, Talgat; Chen, William C W; Mansurov, Nurlan; Issabekova, Assel; Zhakupova, Jamilya

2017-09-01

The immune system plays a crucial role in the initiation, development, and resolution of inflammation following myocardial infarction (MI). The lack of oxygen and nutrients causes the death of cardiomyocytes and leads to the exposure of danger-associated molecular patterns that are recognized by the immune system to initiate inflammation. At the initial stage of post-MI inflammation, the immune system further damages cardiac tissue to clear cell debris. The excessive production of reactive oxygen species (ROS) by immune cells and the inability of the anti-oxidant system to neutralize ROS cause oxidative stress that further aggravates inflammation. On the other hand, the cells of both innate and adaptive immune system and their secreted factors are critically instrumental in the very dynamic and complex processes of regulating inflammation and mediating cardiac repair. It is important to decipher the balance between detrimental and beneficial effects of the immune system in MI. This enables us to identify better therapeutic targets for reducing the infarct size, sustaining the cardiac function, and minimizing the likelihood of heart failure. This review discusses the role of both innate and adaptive immune systems in cardiac tissue damage and repair in experimental models of MI.

Exercise for the heart: signaling pathways

PubMed Central

Zhang, Haifeng; Xiao, Junjie; Li, Xinli

2015-01-01

Physical exercise, a potent functional intervention in protecting against cardiovascular diseases, is a hot topic in recent years. Exercise has been shown to reduce cardiac risk factors, protect against myocardial damage, and increase cardiac function. This improves quality of life and decreases mortality and morbidity in a variety of cardiovascular diseases, including myocardial infarction, cardiac ischemia/reperfusion injury, diabetic cardiomyopathy, cardiac aging, and pulmonary hypertension. The cellular adaptation to exercise can be associated with both endogenous and exogenous factors: 1) exercise induces cardiac growth via hypertrophy and renewal of cardiomyocytes, and 2) exercise induces endothelial progenitor cells to proliferate, migrate and differentiate into mature endothelial cells, giving rise to endothelial regeneration and angiogenesis. The cellular adaptations associated with exercise are due to the activation of several signaling pathways, in particular, the growth factor neuregulin1 (NRG1)-ErbB4-C/EBPβ and insulin-like growth factor (IGF)-1-PI3k-Akt signaling pathways. Of interest, microRNAs (miRNAs, miRs) such as miR-222 also play a major role in the beneficial effects of exercise. Thus, exploring the mechanisms mediating exercise-induced benefits will be instrumental for devising new effective therapies against cardiovascular diseases. PMID:26318584

A simplified method for identification of human cardiac myosin heavy-chain isoforms.

PubMed

Piao, Shengfu; Yu, Fushun; Mihm, Michael J; Reiser, Peter J; McCarthy, Patrick M; Van Wagoner, David R; Bauer, John Anthony

2003-02-01

Cardiac myosin is a central participant in the cross-bridge cycling that mediates myocyte contraction and consists of multiple subunits that mediate both hydrolysis of ATP and mechanical production of contractile force Two isoforms of myosin heavy chain (MHC- alpha and MHC- beta ) are known to exist in mammalian cardiac tissue, and it is within this myosin subunit that ATPase activity resides. These isoforms differ by less than 0.2% in total molecular mass and amino acid sequence, but, strikingly, influence the rate and efficiency of energy utilization for generation of contractile force. Changes in the MHC- alpha /MHC- beta ratio has been classically viewed as an adaptation of a failing myocyte in both animal models and humans; however, their measurement has traditionally required specialized preparations and materials for sufficient resolution. Here we describe a greatly simplified method for routine assessments of myosin isoform composition in human cardiac tissues. The primary advantages of our approach include higher throughput and reduced supply costs with no apparent loss of statistical power, reproducibility or achieved results. Use of this more convenient method may provide enhanced access to an otherwise specialized technique and could provide additional opportunity for investigation of cardiac myocyte adaptive changes.

Turning crocodilian hearts into bird hearts: growth rates are similar for alligators with and without right-to-left cardiac shunt

PubMed Central

Eme, John; Gwalthney, June; Owerkowicz, Tomasz; Blank, Jason M.; Hicks, James W.

2010-01-01

The functional and possible adaptive significance of non-avian reptiles' dual aortic arch system and the ability of all non-avian reptiles to perform central vascular cardiac shunts have been of great interest to comparative physiologists. The unique cardiac anatomy of crocodilians – a four-chambered heart with the dual aortic arch system – allows for only right-to-left (R–L; pulmonary bypass) cardiac shunt and for surgical elimination of this shunt. Surgical removal of the R–L shunt, by occluding the left aorta (LAo) upstream and downstream of the foramen of Panizza, results in a crocodilian with an obligatory, avian/mammalian central circulation. In this study, R–L cardiac shunt was eliminated in age-matched, female American alligators (Alligator mississippiensis; 5–7 months of age). We tested the hypothesis that surgical elimination of R–L cardiac shunt would impair growth (a readily measured proxy for fitness) compared with sham-operated, age-matched controls, especially in animals subjected to exhaustive exercise. While regular exercise caused a decrease in size (snout-to-vent length, head length and body mass), elimination of the capacity for R–L cardiac shunt did not greatly reduce animal growth, despite a chronic ventricular enlargement in surgically altered juvenile alligators. We speculate that, despite being slightly smaller, alligators with an occluded LAo would have reached sexual maturity in the same breeding season as control alligators. This study suggests that crocodilian R–L cardiac shunt does not provide an adaptive advantage for juvenile alligator growth and supports the logic that cardiac shunts persist in crocodilians because they have not been selected against. PMID:20639429

Ubiquitous health monitoring and real-time cardiac arrhythmias detection: a case study.

PubMed

Li, Jian; Zhou, Haiying; Zuo, Decheng; Hou, Kun-Mean; De Vaulx, Christophe

2014-01-01

As the symptoms and signs of heart diseases that cause sudden cardiac death, cardiac arrhythmia has attracted great attention. Due to limitations in time and space, traditional approaches to cardiac arrhythmias detection fail to provide a real-time continuous monitoring and testing service applicable in different environmental conditions. Integrated with the latest technologies in ECG (electrocardiograph) analysis and medical care, the pervasive computing technology makes possible the ubiquitous cardiac care services, and thus brings about new technical challenges, especially in the formation of cardiac care architecture and realization of the real-time automatic ECG detection algorithm dedicated to care devices. In this paper, a ubiquitous cardiac care prototype system is presented with its architecture framework well elaborated. This prototype system has been tested and evaluated in all the clinical-/home-/outdoor-care modes with a satisfactory performance in providing real-time continuous cardiac arrhythmias monitoring service unlimitedly adaptable in time and space.

An Optimized and Simplified System of Mouse Embryonic Stem Cell Cardiac Differentiation for the Assessment of Differentiation Modifiers

PubMed Central

Hartman, Matthew E.; Librande, Jason R.; Medvedev, Ivan O.; Ahmad, Rabiah N.; Moussavi-Harami, Farid; Gupta, Pritha P.; Chien, Wei-Ming; Chin, Michael T.

2014-01-01

Generating cardiomyocytes from embryonic stem cells is an important technique for understanding cardiovascular development, the origins of cardiovascular diseases and also for providing potential reagents for cardiac repair. Numerous methods have been published but often are technically challenging, complex, and are not easily adapted to assessment of specific gene contributions to cardiac myocyte differentiation. Here we report the development of an optimized protocol to induce the differentiation of mouse embryonic stem cells to cardiac myocytes that is simplified and easily adapted for genetic studies. Specifically, we made four critical findings that distinguish our protocol: 1) mouse embryonic stem cells cultured in media containing CHIR99021 and PD0325901 to maintain pluripotency will efficiently form embryoid bodies containing precardiac mesoderm when cultured in these factors at a reduced dosage, 2) low serum conditions promote cardiomyocyte differentiation and can be used in place of commercially prepared StemPro nutrient supplement, 3) the Wnt inhibitor Dkk-1 is dispensable for efficient cardiac differentiation and 4) tracking differentiation efficiency may be done with surface expression of PDGFRα alone. In addition, cardiac mesodermal precursors generated by this system can undergo lentiviral infection to manipulate the expression of specific target molecules to assess effects on cardiac myocyte differentiation and maturation. Using this approach, we assessed the effects of CHF1/Hey2 on cardiac myocyte differentiation, using both gain and loss of function. Overexpression of CHF1/Hey2 at the cardiac mesoderm stage had no apparent effect on cardiac differentiation, while knockdown of CHF1/Hey2 resulted in increased expression of atrial natriuretic factor and connexin 43, suggesting an alteration in the phenotype of the cardiomyocytes. In summary we have generated a detailed and simplified protocol for generating cardiomyocytes from mES cells that is optimized for investigating factors that affect cardiac differentiation. PMID:24667642

Functional adaptations of the coronary microcirculation to anaemia in fetal sheep.

PubMed

Jonker, Sonnet S; Davis, Lowell; Soman, Divya; Belcik, J Todd; Davidson, Brian P; Atkinson, Tamara M; Wilburn, Adrienne; Louey, Samantha; Giraud, George D; Lindner, Jonathan R

2016-11-01

In fetuses, chronic anaemia stimulates cardiac growth; simultaneously, blood flow to the heart muscle itself is increased, and reserve blood flow capacity of the coronary vascular bed is preserved. Here we examined functional adaptations of the capillaries and small blood vessels responsible for delivering oxygen to the anaemic fetal heart muscle using contrast-enhanced echocardiography. We demonstrate that coronary microvascular flux rate doubled in anaemic fetuses compared to control fetuses, both at rest and during maximal flow, suggesting reduced microvascular resistance consistent with capillary widening. Cardiac fractional microvascular blood volume was not greater in anaemic fetuses, suggesting that growth of new microvascular vessels does not contribute to the increased flow per volume of myocardium. These unusual changes in microvascular function during anaemia may indicate novel adaptive strategies in the fetal heart. Fetal anaemia causes cardiac adaptations that have immediate and life-long repercussions on heart function and health. It is known that resting and maximal coronary conductance both increase during chronic fetal anaemia, but the coronary microvascular changes responsible for the adaptive response are unknown. Until recently, technical limitations have prevented quantifying functional capillary-level adaptations in the in vivo fetal heart. Our objective was to characterise functional microvascular adaptations in chronically anaemic fetal sheep. Chronically instrumented fetuses were randomized to a control group (n = 11) or were made anaemic by isovolumetric haemorrhage (n = 12) for 1 week prior to myocardial contrast echocardiography at 85% of gestation. Anaemia augmented cardiac mass by 23% without changing body weight. In anaemic fetuses, microvascular blood flow per volume of myocardium was twice that of control fetuses at rest, during vasodilatory hyperaemia, and during hyperaemia plus increased aortic pressure. The elevated blood flow was attributable almost entirely to an increase in microvascular blood flux rate whereas microvascular blood volumes were not different between groups at baseline, during hyperaemia, or with hyperaemia plus increased aortic pressure. Increased coronary microvascular flux rate in response to chronic fetal anaemia is consistent with expected reductions in capillary resistance from capillary diameter widening detected in earlier histological studies. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

Desipramine prevents cardiac gap junction uncoupling.

PubMed

Jozwiak, Joanna; Dietze, Anna; Grover, Rajiv; Savtschenko, Alex; Etz, Christian; Mohr, Friedrich W; Dhein, Stefan

2012-11-01

Uncoupling of cardiac gap junction channels is an important arrhythmogenic mechanism in ischemia/reperfusion. Antiarrhythmic peptide AAP10 (H-Gly-Ala-Gly-Hyp-Pro-Tyr-CONH(2)) has been shown to prevent acidosis-induced uncoupling and ischemia-related increase in dispersion. Previous structure-effect investigations and subsequent computer modeling studies indicated that the tricyclic antidepressant desipramine may exert similar effects as AAP10. We assessed the binding of (14)C-AAP10 to membranes of rabbit cardiac ventricles and its displacement with desipramine in a classical radioligand binding and competition study. Gap junction currents were measured between isolated pairs of human atrial cardiomyocytes under normal and acidotic (pH 6.3) conditions with or without 1 μmol/l desipramine using dual whole-cell voltage clamp. The effect of 1 μmol/l desipramine was assessed in isolated rabbit hearts (Langendorff technique) undergoing local ischemia by coronary occlusion with 256-channel electrophysiological mapping and subsequent analysis of connexin43 (Cx43) expression, phosphorylation (Western blot), and subcellular localization (immunohistology). We found saturable (14)C-AAP10 binding to cardiac membranes (K (D), 0.29 ± 0.11 nmol/l; B (max), 42.5 ± 7.2 pmol/mg) which could be displaced by desipramine with a K (D.High) = 0.14 μmol/l and a K (D.Low) = 22 μmol/l. Acidosis reduced the gap junction conductance in human cardiomyocyte pairs from 24.1 ± 4.7 to 11.5 ± 2.5 nS, which could be significantly reversed by desipramine (26.6 ± 4.8 nS). In isolated hearts, ischemia resulted in significantly increased dispersion of activation-recovery intervals, loss of membrane Cx43, and dephosphorylation of Cx43, which all could be prevented by desipramine. Desipramine seems to prevent the uncoupling of cardiac gap junctions and ischemia-related increase in dispersion.

Molecular and Functional Effects of a Splice Site Mutation in the MYL2 Gene Associated with Cardioskeletal Myopathy and Early Cardiac Death in Infants

PubMed Central

Zhou, Zhiqun; Huang, Wenrui; Liang, Jingsheng; Szczesna-Cordary, Danuta

2016-01-01

The homozygous appearance of the intronic mutation (IVS6-1) in the MYL2 gene encoding for myosin ventricular/slow-twitch skeletal regulatory light chain (RLC) was recently linked to the development of slow skeletal muscle fiber type I hypotrophy and early cardiac death. The IVS6-1 (c403-1G>C) mutation resulted from a cryptic splice site in MYL2 causing a frameshift and replacement of the last 32 codons by 19 different amino acids in the RLC mutant protein. Infants who were IVS6-1+∕+-positive died between 4 and 6 months of age due to cardiomyopathy and heart failure. In this report we have investigated the molecular mechanism and functional consequences associated with the IVS6-1 mutation using recombinant human cardiac IVS6-1 and wild-type (WT) RLC proteins. Recombinant proteins were reconstituted into RLC-depleted porcine cardiac muscle preparations and subjected to enzymatic and functional assays. IVS6-1-RLC showed decreased binding to the myosin heavy chain (MHC) compared with WT, and IVS6-1-reconstituted myosin displayed reduced binding to actin in rigor. The IVS6-1 myosin demonstrated a significantly lower Vmax of the actin-activated myosin ATPase activity compared with WT. In stopped-flow experiments, IVS6-1 myosin showed slower kinetics of the ATP induced dissociation of the acto-myosin complex and a significantly reduced slope of the kobs-[MgATP] relationship compared to WT. In skinned porcine cardiac muscles, RLC-depleted and IVS6-1 reconstituted muscle strips displayed a significant decrease in maximal contractile force and a significantly increased Ca2+ sensitivity, both hallmarks of hypertrophic cardiomyopathy-associated mutations in MYL2. Our results showed that the amino-acid changes in IVS6-1 were sufficient to impose significant conformational alterations in the RLC protein and trigger a series of abnormal protein-protein interactions in the cardiac muscle sarcomere. Notably, the mutation disrupted the RLC-MHC interaction and the steady-state and kinetics of the acto-myosin interaction. Specifically, slower myosin cross-bridge turnover rates and slower second-order MgATP binding rates of acto-myosin interactions were observed in IVS6-1 vs. WT reconstituted cardiac preparations. Our in vitro results suggest that when placed in vivo, IVS6-1 may lead to cardiomyopathy and early death of homozygous infants by severely compromising the ability of myosin to develop contractile force and maintain normal systolic and diastolic cardiac function. PMID:27378946

Characterization of the slow calcium channel binding sites for ( sup 3 H)SR 33557 in rat heart sarcolemmal membranes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chatelain, P.; Beaufort, P.; Meysmans, L.

1991-01-01

SR 33557 represents a new class of compounds (indolizine sulfone) that inhibit L-type Ca2+ channels. ({sup 3}H)SR 33557 has been shown to bind with high affinity (Kd congruent to 0.36 nM, calculated from saturation isotherms and association/dissociation kinetics) to a single class of sites in a purified preparation of rat cardiac sarcolemmal membranes. The binding was found to be saturable and reversible. The maximal binding capacity was in approximately 1:1 stoichiometry with that of other Ca2+ channel antagonists. Various divalent cations (Mg2+, Mn2+, Ca2+, Ba2+, and Cd2+) were shown to inhibit specific ({sup 3}H)SR 33557 binding, with Cd2+ being themore » most potent. Among several receptor or channel ligands (including omega-conotoxin and Na+ and K+ channel modulators), only the L-type Ca2+ channel antagonists were found to displace ({sup 3}H)SR 33557. However, dihydropyridines, phenylalkylamines, benzothiazepines, and diphenylbutylpiperidines were found to inhibit ({sup 3}H)SR 33557 in a noncompetitive manner as demonstrated by displacement and saturation experiments in addition to dissociation kinetics. From these results, we suggest that SR 33557 binds with high affinity to a unique site on the L-type Ca2+ channel found in rat cardiac sarcolemmal membranes.« less

Central adaptations in aerobic circuit versus walking/jogging trained cardiac patients.

PubMed

Goodman, L S; McKenzie, D C; Nath, C R; Schamberger, W; Taunton, J E; Ammann, W C

1995-06-01

This study was done to determine (a) whether in coronary artery disease (CAD) left ventricular (LV) adaptations differed after 6 months of walking/jogging (legs-only, LO) versus aerobic circuit training (arms and legs, AL) versus a control group, and (b) whether a transfer of fitness to the untrained arms in the LO group was related to superior LV adaptations. Peak oxygen uptake for arm and leg ergometry and for cycle ergometry using radionuclide cardiac angiography were performed before and after training. Leg and arm VO2peak increased significantly by 13% in the AL group, and by 13% and 7%, respectively, for the LO group. LV function was greater after training for the LO versus the AL group. Improvements in systolic and diastolic function and a speculated hypervolemia explain these LV adaptations. In CAD patients, walking/jogging produces greater LV function improvements versus circuit training, possibly due to differences in the exercised muscle mass.

Investigating the transcriptional control of cardiovascular development

PubMed Central

Kathiriya, Irfan S.; Nora, Elphege P.; Bruneau, Benoit G.

2015-01-01

Transcriptional regulation of thousands of genes instructs complex morphogenetic and molecular events for heart development. Cardiac transcription factors (TFs) choreograph gene expression at each stage of differentiation by interacting with co-factors, including chromatin-modifying enzymes, and by binding to a constellation of regulatory DNA elements. Here, we present salient examples relevant to cardiovascular development and heart disease and review techniques that can sharpen our understanding of cardiovascular biology. We discuss the interplay between cardiac TFs, cis-regulatory elements and chromatin as dynamic regulatory networks, to orchestrate sequential deployment of the cardiac gene expression program. PMID:25677518

Cardiac Concomitants of Feedback and Prediction Error Processing in Reinforcement Learning.

PubMed

Kastner, Lucas; Kube, Jana; Villringer, Arno; Neumann, Jane

2017-01-01

Successful learning hinges on the evaluation of positive and negative feedback. We assessed differential learning from reward and punishment in a monetary reinforcement learning paradigm, together with cardiac concomitants of positive and negative feedback processing. On the behavioral level, learning from reward resulted in more advantageous behavior than learning from punishment, suggesting a differential impact of reward and punishment on successful feedback-based learning. On the autonomic level, learning and feedback processing were closely mirrored by phasic cardiac responses on a trial-by-trial basis: (1) Negative feedback was accompanied by faster and prolonged heart rate deceleration compared to positive feedback. (2) Cardiac responses shifted from feedback presentation at the beginning of learning to stimulus presentation later on. (3) Most importantly, the strength of phasic cardiac responses to the presentation of feedback correlated with the strength of prediction error signals that alert the learner to the necessity for behavioral adaptation. Considering participants' weight status and gender revealed obesity-related deficits in learning to avoid negative consequences and less consistent behavioral adaptation in women compared to men. In sum, our results provide strong new evidence for the notion that during learning phasic cardiac responses reflect an internal value and feedback monitoring system that is sensitive to the violation of performance-based expectations. Moreover, inter-individual differences in weight status and gender may affect both behavioral and autonomic responses in reinforcement-based learning.

Cardiac Concomitants of Feedback and Prediction Error Processing in Reinforcement Learning

PubMed Central

Kastner, Lucas; Kube, Jana; Villringer, Arno; Neumann, Jane

2017-01-01

Successful learning hinges on the evaluation of positive and negative feedback. We assessed differential learning from reward and punishment in a monetary reinforcement learning paradigm, together with cardiac concomitants of positive and negative feedback processing. On the behavioral level, learning from reward resulted in more advantageous behavior than learning from punishment, suggesting a differential impact of reward and punishment on successful feedback-based learning. On the autonomic level, learning and feedback processing were closely mirrored by phasic cardiac responses on a trial-by-trial basis: (1) Negative feedback was accompanied by faster and prolonged heart rate deceleration compared to positive feedback. (2) Cardiac responses shifted from feedback presentation at the beginning of learning to stimulus presentation later on. (3) Most importantly, the strength of phasic cardiac responses to the presentation of feedback correlated with the strength of prediction error signals that alert the learner to the necessity for behavioral adaptation. Considering participants' weight status and gender revealed obesity-related deficits in learning to avoid negative consequences and less consistent behavioral adaptation in women compared to men. In sum, our results provide strong new evidence for the notion that during learning phasic cardiac responses reflect an internal value and feedback monitoring system that is sensitive to the violation of performance-based expectations. Moreover, inter-individual differences in weight status and gender may affect both behavioral and autonomic responses in reinforcement-based learning. PMID:29163004

Translational neurocardiology: preclinical models and cardioneural integrative aspects

PubMed Central

Andresen, M. C.; Armour, J. A.; Billman, G. E.; Chen, P.‐S.; Foreman, R. D.; Herring, N.; O'Leary, D. S.; Sabbah, H. N.; Schultz, H. D.; Sunagawa, K.; Zucker, I. H.

2016-01-01

Abstract Neuronal elements distributed throughout the cardiac nervous system, from the level of the insular cortex to the intrinsic cardiac nervous system, are in constant communication with one another to ensure that cardiac output matches the dynamic process of regional blood flow demand. Neural elements in their various ‘levels’ become differentially recruited in the transduction of sensory inputs arising from the heart, major vessels, other visceral organs and somatic structures to optimize neuronal coordination of regional cardiac function. This White Paper will review the relevant aspects of the structural and functional organization for autonomic control of the heart in normal conditions, how these systems remodel/adapt during cardiac disease, and finally how such knowledge can be leveraged in the evolving realm of autonomic regulation therapy for cardiac therapeutics. PMID:27098459

Increased Cardiac Arrhythmogenesis Associated With Gap Junction Remodeling With Upregulation of RNA-Binding Protein FXR1.

PubMed

Chu, Miensheng; Novak, Stefanie Mares; Cover, Cathleen; Wang, Anne A; Chinyere, Ikeotunye Royal; Juneman, Elizabeth B; Zarnescu, Daniela C; Wong, Pak Kin; Gregorio, Carol C

2018-02-06

Gap junction remodeling is well established as a consistent feature of human heart disease involving spontaneous ventricular arrhythmia. The mechanisms responsible for gap junction remodeling that include alterations in the distribution of, and protein expression within, gap junctions are still debated. Studies reveal that multiple transcriptional and posttranscriptional regulatory pathways are triggered in response to cardiac disease, such as those involving RNA-binding proteins. The expression levels of FXR1 (fragile X mental retardation autosomal homolog 1), an RNA-binding protein, are critical to maintain proper cardiac muscle function; however, the connection between FXR1 and disease is not clear. To identify the mechanisms regulating gap junction remodeling in cardiac disease, we sought to identify the functional properties of FXR1 expression, direct targets of FXR1 in human left ventricle dilated cardiomyopathy (DCM) biopsy samples and mouse models of DCM through BioID proximity assay and RNA immunoprecipitation, how FXR1 regulates its targets through RNA stability and luciferase assays, and functional consequences of altering the levels of this important RNA-binding protein through the analysis of cardiac-specific FXR1 knockout mice and mice injected with 3xMyc-FXR1 adeno-associated virus. FXR1 expression is significantly increased in tissue samples from human and mouse models of DCM via Western blot analysis. FXR1 associates with intercalated discs, and integral gap junction proteins Cx43 (connexin 43), Cx45 (connexin 45), and ZO-1 (zonula occludens-1) were identified as novel mRNA targets of FXR1 by using a BioID proximity assay and RNA immunoprecipitation. Our findings show that FXR1 is a multifunctional protein involved in translational regulation and stabilization of its mRNA targets in heart muscle. In addition, introduction of 3xMyc-FXR1 via adeno-associated virus into mice leads to the redistribution of gap junctions and promotes ventricular tachycardia, showing the functional significance of FXR1 upregulation observed in DCM. In DCM, increased FXR1 expression appears to play an important role in disease progression by regulating gap junction remodeling. Together this study provides a novel function of FXR1, namely, that it directly regulates major gap junction components, contributing to proper cell-cell communication in the heart. © 2017 American Heart Association, Inc.

Quantification of ventricular β2 -adrenoceptor density and ligand binding affinity in wild sockeye salmon Oncorhynchus nerka smolts using a novel modification to the tritiated ligand technique.

PubMed

Goulding, A T; Farrell, A P

2016-05-01

A new, image-based, tritiated ligand technique for measuring cardiac β2 -adrenoceptor (β2 -AR) binding characteristics was developed and validated with adult rainbow trout Oncorhynchus mykiss hearts so that the tissue limitation of traditional receptor binding techniques could be overcome and measurements could be made in hearts nearly 14-times smaller than previously used. The myocardial cell-surface (functional) β2 -AR density of O. nerka smolts sampled at the headwaters of the Chilko River was 54·2 fmol mg protein(-1) and about half of that previously found in return migrating adults of the same population, but still more than twice that of adult hatchery O. mykiss (21·1 fmol mg protein(-1) ). This technique now opens the possibility of investigating cardiac receptor density in a much wider range of fish species and life stages. © 2016 The Fisheries Society of the British Isles.

Popeye domain containing proteins are essential for stress-mediated modulation of cardiac pacemaking in mice

PubMed Central

Froese, Alexander; Breher, Stephanie S.; Waldeyer, Christoph; Schindler, Roland F.R.; Nikolaev, Viacheslav O.; Rinné, Susanne; Wischmeyer, Erhard; Schlueter, Jan; Becher, Jan; Simrick, Subreena; Vauti, Franz; Kuhtz, Juliane; Meister, Patrick; Kreissl, Sonja; Torlopp, Angela; Liebig, Sonja K.; Laakmann, Sandra; Müller, Thomas D.; Neumann, Joachim; Stieber, Juliane; Ludwig, Andreas; Maier, Sebastian K.; Decher, Niels; Arnold, Hans-Henning; Kirchhof, Paulus; Fabritz, Larissa; Brand, Thomas

2012-01-01

Cardiac pacemaker cells create rhythmic pulses that control heart rate; pacemaker dysfunction is a prevalent disorder in the elderly, but little is known about the underlying molecular causes. Popeye domain containing (Popdc) genes encode membrane proteins with high expression levels in cardiac myocytes and specifically in the cardiac pacemaking and conduction system. Here, we report the phenotypic analysis of mice deficient in Popdc1 or Popdc2. ECG analysis revealed severe sinus node dysfunction when freely roaming mutant animals were subjected to physical or mental stress. In both mutants, bradyarrhythmia developed in an age-dependent manner. Furthermore, we found that the conserved Popeye domain functioned as a high-affinity cAMP-binding site. Popdc proteins interacted with the potassium channel TREK-1, which led to increased cell surface expression and enhanced current density, both of which were negatively modulated by cAMP. These data indicate that Popdc proteins have an important regulatory function in heart rate dynamics that is mediated, at least in part, through cAMP binding. Mice with mutant Popdc1 and Popdc2 alleles are therefore useful models for the dissection of the mechanisms causing pacemaker dysfunction and could aid in the development of strategies for therapeutic intervention. PMID:22354168

Mef2c Regulates Transcription of the Extracellular Matrix Protein Cartilage Link Protein 1 in the Developing Murine Heart

PubMed Central

Phelps, Aimee L.; Ghatnekar, Angela V.; Barth, Jeremy L.; Norris, Russell A.; Wessels, Andy

2013-01-01

Cartilage Link Protein 1 (Crtl1) is an extracellular matrix (ECM) protein that stabilizes the interaction between hyaluronan and versican and is expressed in endocardial and endocardially-derived cells in the developing heart, including cells in the atrioventricular (AV) and outflow tract (OFT) cushions. Previous investigations into the transcriptional regulation of the Crtl1 gene have shown that Sox9 regulates Crtl1 expression in both cartilage and the AV valves. The cardiac transcription factor Mef2c is involved in the regulation of gene expression in cardiac and skeletal muscle cell lineages. In this study we have investigated the potential role of Mef2c in the regulation of ECM production in the endocardial and mesenchymal cell lineages of the developing heart. We demonstrate that the Crtl1 5′ flanking region contains two highly conserved Mef2 binding sites and that Mef2c is able to bind to these sites in vivo during cardiovascular development. Additionally, we show that Crtl1 transcription is dependent on Mef2c expression in fetal mitral valve interstitial cells (VICs). Combined, these findings highlight a new role for Mef2c in cardiac development and the regulation of cardiac extracellular matrix protein expression. PMID:23468913

Cardiomyocyte Overexpression of FABP4 Aggravates Pressure Overload-Induced Heart Hypertrophy.

PubMed

Zhang, Ji; Qiao, Congzhen; Chang, Lin; Guo, Yanhong; Fan, Yanbo; Villacorta, Luis; Chen, Y Eugene; Zhang, Jifeng

2016-01-01

Fatty acid binding protein 4 (FABP4) is a member of the intracellular lipid-binding protein family, responsible for the transportation of fatty acids. It is considered to express mainly in adipose tissues, and be strongly associated with inflammation, obesity, diabetes and cardiovasculardiseases. Here we report that FABP4 is also expressed in cardiomyocytes and plays an important role in regulating heart function under pressure overload. We generated heart-specific transgenic FABP4 (FABP4-TG) mice using α myosin-heavy chain (α-MHC) promoter and human FABP4 sequence, resulting in over-expression of FABP4 in cardiomyocytes. The FABP4-TG mice displayed normal cardiac morphology and contractile function. When they were subjected to the transverse aorta constriction (TAC) procedure, the FABP4-TG mice developed more cardiac hypertrophy correlated with significantly increased ERK phosphorylation, compared with wild type controls. FABP4 over-expression in cardiomyocytes activated phosphor-ERK signal and up-regulate the expression of cardiac hypertrophic marker genes. Conversely, FABP4 induced phosphor-ERK signal and hypertrophic gene expressions can be markedly inhibited by an ERK inhibitor PD098059 as well as the FABP4 inhibitor BMS309403. These results suggest that FABP4 over-expression in cardiomyocytes can aggravate the development of cardiac hypertrophy through the activation of ERK signal pathway.

Cardiomyocyte Overexpression of FABP4 Aggravates Pressure Overload-Induced Heart Hypertrophy

PubMed Central

Zhang, Ji; Qiao, Congzhen; Chang, Lin; Guo, Yanhong; Fan, Yanbo; Villacorta, Luis; Chen, Y. Eugene; Zhang, Jifeng

2016-01-01

Fatty acid binding protein 4 (FABP4) is a member of the intracellular lipid-binding protein family, responsible for the transportation of fatty acids. It is considered to express mainly in adipose tissues, and be strongly associated with inflammation, obesity, diabetes and cardiovasculardiseases. Here we report that FABP4 is also expressed in cardiomyocytes and plays an important role in regulating heart function under pressure overload. We generated heart-specific transgenic FABP4 (FABP4-TG) mice using α myosin-heavy chain (α-MHC) promoter and human FABP4 sequence, resulting in over-expression of FABP4 in cardiomyocytes. The FABP4-TG mice displayed normal cardiac morphology and contractile function. When they were subjected to the transverse aorta constriction (TAC) procedure, the FABP4-TG mice developed more cardiac hypertrophy correlated with significantly increased ERK phosphorylation, compared with wild type controls. FABP4 over-expression in cardiomyocytes activated phosphor-ERK signal and up-regulate the expression of cardiac hypertrophic marker genes. Conversely, FABP4 induced phosphor-ERK signal and hypertrophic gene expressions can be markedly inhibited by an ERK inhibitor PD098059 as well as the FABP4 inhibitor BMS309403. These results suggest that FABP4 over-expression in cardiomyocytes can aggravate the development of cardiac hypertrophy through the activation of ERK signal pathway. PMID:27294862

Remodeling of repolarization and arrhythmia susceptibility in a myosin-binding protein C knockout mouse model.

PubMed

Toib, Amir; Zhang, Chen; Borghetti, Giulia; Zhang, Xiaoxiao; Wallner, Markus; Yang, Yijun; Troupes, Constantine D; Kubo, Hajime; Sharp, Thomas E; Feldsott, Eric; Berretta, Remus M; Zalavadia, Neil; Trappanese, Danielle M; Harper, Shavonn; Gross, Polina; Chen, Xiongwen; Mohsin, Sadia; Houser, Steven R

2017-09-01

Hypertrophic cardiomyopathy (HCM) is one of the most common genetic cardiac diseases and among the leading causes of sudden cardiac death (SCD) in the young. The cellular mechanisms leading to SCD in HCM are not well known. Prolongation of the action potential (AP) duration (APD) is a common feature predisposing hypertrophied hearts to SCD. Previous studies have explored the roles of inward Na + and Ca 2+ in the development of HCM, but the role of repolarizing K + currents has not been defined. The objective of this study was to characterize the arrhythmogenic phenotype and cellular electrophysiological properties of mice with HCM, induced by myosin-binding protein C (MyBPC) knockout (KO), and to test the hypothesis that remodeling of repolarizing K + currents causes APD prolongation in MyBPC KO myocytes. We demonstrated that MyBPC KO mice developed severe hypertrophy and cardiac dysfunction compared with wild-type (WT) control mice. Telemetric electrocardiographic recordings of awake mice revealed prolongation of the corrected QT interval in the KO compared with WT control mice, with overt ventricular arrhythmias. Whole cell current- and voltage-clamp experiments comparing KO with WT mice demonstrated ventricular myocyte hypertrophy, AP prolongation, and decreased repolarizing K + currents. Quantitative RT-PCR analysis revealed decreased mRNA levels of several key K + channel subunits. In conclusion, decrease in repolarizing K + currents in MyBPC KO ventricular myocytes contributes to AP and corrected QT interval prolongation and could account for the arrhythmia susceptibility. NEW & NOTEWORTHY Ventricular myocytes isolated from the myosin-binding protein C knockout hypertrophic cardiomyopathy mouse model demonstrate decreased repolarizing K + currents and action potential and QT interval prolongation, linking cellular repolarization abnormalities with arrhythmia susceptibility and the risk for sudden cardiac death in hypertrophic cardiomyopathy. Copyright © 2017 the American Physiological Society.

Force properties of skinned cardiac muscle following increasing volumes of aerobic exercise in rats.

PubMed

Boldt, Kevin Rudi; Rios, Jaqueline Lourdes; Joumaa, Venus; Herzog, Walter

2018-05-03

The positive effects of chronic endurance exercise training on health and performance have been well documented. These positive effects have been evaluated primarily at the structural level, and work has begun to evaluate mechanical adaptations of the myocardium. However, it remains poorly understood how the volume of exercise training affects cardiac adaptation. In order to gain some understanding, we subjected three-month-old Sprague-Dawley rats (N=23) to treadmill running for eleven weeks at one of three exercise volumes (moderate, high, and extra high). Following training, hearts were excised and mechanical testing was completed on skinned trabecular fiber bundles. Performance on a maximal fitness test was dose-dependent upon training volume, where greater levels of training led to greater performance. No differences were observed between animals from any group for active stress production. Heart mass and passive stress increases in a dose-dependent manner for animals in the control, moderate, and high duration groups. However, hearts from animals in the extra high duration group presented with inhibited responses for heart mass and passive stress, despite performing greatest on a graded treadmill fitness test. These results suggest that heart mass and passive stress adapt in a dose-dependent manner, until exercise becomes excessive and adaptation is inhibited. Our findings are in agreement with the beneficial role exercise has in cardiac adaptation. However, excessive exercise comes with risks of maladaptation which must be weighed against the desire to increase performance.

The Andean Adaptive Toolkit to Counteract High Altitude Maladaptation: Genome-Wide and Phenotypic Analysis of the Collas

PubMed Central

Eichstaedt, Christina A.; Antão, Tiago; Pagani, Luca; Cardona, Alexia; Kivisild, Toomas; Mormina, Maru

2014-01-01

During their migrations out of Africa, humans successfully colonised and adapted to a wide range of habitats, including extreme high altitude environments, where reduced atmospheric oxygen (hypoxia) imposes a number of physiological challenges. This study evaluates genetic and phenotypic variation in the Colla population living in the Argentinean Andes above 3500 m and compares it to the nearby lowland Wichí group in an attempt to pinpoint evolutionary mechanisms underlying adaptation to high altitude hypoxia. We genotyped 730,525 SNPs in 25 individuals from each population. In genome-wide scans of extended haplotype homozygosity Collas showed the strongest signal around VEGFB, which plays an essential role in the ischemic heart, and ELTD1, another gene crucial for heart development and prevention of cardiac hypertrophy. Moreover, pathway enrichment analysis showed an overrepresentation of pathways associated with cardiac morphology. Taken together, these findings suggest that Colla highlanders may have evolved a toolkit of adaptative mechanisms resulting in cardiac reinforcement, most likely to counteract the adverse effects of the permanently increased haematocrit and associated shear forces that characterise the Andean response to hypoxia. Regulation of cerebral vascular flow also appears to be part of the adaptive response in Collas. These findings are not only relevant to understand the evolution of hypoxia protection in high altitude populations but may also suggest new avenues for medical research into conditions where hypoxia constitutes a detrimental factor. PMID:24686296

Nox4 reprograms cardiac substrate metabolism via protein O-GlcNAcylation to enhance stress adaptation

PubMed Central

Nabeebaccus, Adam A.; Zoccarato, Anna; Hafstad, Anne D.; Santos, Celio X.C.; Brewer, Alison C.; Zhang, Min; Beretta, Matteo; West, James A.; Eykyn, Thomas R.; Shah, Ajay M.

2017-01-01

Cardiac hypertrophic remodeling during chronic hemodynamic stress is associated with a switch in preferred energy substrate from fatty acids to glucose, usually considered to be energetically favorable. The mechanistic interrelationship between altered energy metabolism, remodeling, and function remains unclear. The ROS-generating NADPH oxidase-4 (Nox4) is upregulated in the overloaded heart, where it ameliorates adverse remodeling. Here, we show that Nox4 redirects glucose metabolism away from oxidation but increases fatty acid oxidation, thereby maintaining cardiac energetics during acute or chronic stresses. The changes in glucose and fatty acid metabolism are interlinked via a Nox4-ATF4–dependent increase in the hexosamine biosynthetic pathway, which mediates the attachment of O-linked N-acetylglucosamine (O-GlcNAcylation) to the fatty acid transporter CD36 and enhances fatty acid utilization. These data uncover a potentially novel redox pathway that regulates protein O-GlcNAcylation and reprograms cardiac substrate metabolism to favorably modify adaptation to chronic stress. Our results also suggest that increased fatty acid oxidation in the chronically stressed heart may be beneficial. PMID:29263294

Cardiac function and exercise adaptation in 8 children with LPIN1 mutations.

PubMed

Legendre, Antoine; Khraiche, Diala; Ou, Phalla; Mauvais, François-Xavier; Madrange, Marine; Guemann, Anne-Sophie; Jais, Jean-Philippe; Bonnet, Damien; Hamel, Yamina; de Lonlay, Pascale

2018-03-01

Lipin-1 deficiency is a major cause of rhabdomyolysis that are precipitated by febrile illness. The prognosis is poor, with one-third of patients dying from cardiac arrest during a crisis episode. Apart from acute rhabdomyolysis, most patients are healthy, showing normal clinical and cardiac ultrasound parameters. We report cardiac and exercise examinations of 8 children carrying two LPIN1 mutations. The examinations were performed outside of a myolysis episode, but one patient presented with fever during one examination. All but one patient displayed normal resting cardiac function, as determined by echocardiography. One patient exhibited slight left ventricular dysfunction at rest and a lack of increased stroke volume during cycle ramp exercise. During exercise, peripheral muscle adaptation was impaired in 2 patients compared to healthy controls: they presented an abnormal increase in cardiac output relative to oxygen uptake: dQ/dVO 2 =8.2 and 9.5 (>2DS of controls population). One patient underwent 2 exercise tests; during one test, the patient was febrile, leading to acute rhabdomyolysis in the following hours. He exhibited changes in recovery muscle reoxygenation parameters and an increased dQ/dVO 2 during exercise compared with that under normothermia (7.9 vs 6), which did not lead to acute rhabdomyolysis. The four patients assessed by cardiac 1 H-magnetic resonance spectroscopy exhibited signs of intracardiac steatosis. We observed abnormal haemodynamic profiles during exercise in 3/8 patients with lipin-1 deficiency, suggesting impaired muscle oxidative phosphorylation during exercise. Fever appeared to be an aggravating factor. One patient exhibited moderate cardiac dysfunction, which was possibly related to intracardiac stored lipid toxicity. Copyright © 2018 Elsevier Inc. All rights reserved.

Cardiac-specific overexpression of sarcolipin inhibits sarco(endo)plasmic reticulum Ca2+ ATPase (SERCA2a) activity and impairs cardiac function in mice

PubMed Central

Asahi, Michio; Otsu, Kinya; Nakayama, Hiroyuki; Hikoso, Shungo; Takeda, Toshihiro; Gramolini, Anthony O.; Trivieri, Maria G.; Oudit, Gavin Y.; Morita, Takashi; Kusakari, Yoichiro; Hirano, Shuta; Hongo, Kenichi; Hirotani, Shinichi; Yamaguchi, Osamu; Peterson, Alan; Backx, Peter H.; Kurihara, Satoshi; Hori, Masatsugu; MacLennan, David H.

2004-01-01

Sarcolipin (SLN) inhibits the cardiac sarco(endo)plasmic reticulum Ca2+ ATPase (SERCA2a) by direct binding and is superinhibitory if it binds through phospholamban (PLN). To determine whether overexpression of SLN in the heart might impair cardiac function, transgenic (TG) mice were generated with cardiac-specific overexpression of NF-SLN (SLN tagged at its N terminus with the FLAG epitope). The level of NF-SLN expression (the NF-SLN/PLN expression ratio) was equivalent to that which induces profound superinhibition when coexpressed with PLN and SERCA2a in HEK-293 cells. In TG hearts, the apparent affinity of SERCA2a for Ca2+ was decreased compared with non-TG littermate control hearts. Invasive hemodynamic and echocardiographic analyses revealed impaired cardiac contractility and ventricular hypertrophy in TG mice. Basal PLN phosphorylation was reduced. In isolated papillary muscle subjected to isometric tension, peak amplitudes of Ca2+ transients and peak tensions were reduced, whereas decay times of Ca2+ transients and relaxation times of tension were increased in TG mice. Isoproterenol largely restored contractility in papillary muscle and stimulated PLN phosphorylation to wild-type levels in intact hearts. No compensatory changes in expression of SERCA2a, PLN, ryanodine receptor, and calsequestrin were observed in TG hearts. Coimmunoprecipitation indicated that overexpressed NF-SLN was bound to both SERCA2a and PLN, forming a ternary complex. These data suggest that NF-SLN overexpression inhibits SERCA2a through stabilization of SERCA2a–PLN interaction in the absence of PLN phosphorylation and through the inhibition of PLN phosphorylation. Inhibition of SERCA2a impairs contractility and calcium cycling, but responsiveness to β-adrenergic agonists may prevent progression to heart failure. PMID:15201433

Active compounds in Chinese herbs and medicinal animal products which promote blood circulation via inhibition of Na+, K+-ATPase.

PubMed

Tzen, Jason Tc; Chen, Ronald Jy; Chung, Tse-Yu; Chen, Yi-Ching; Lin, Nan-Hei

2010-01-01

The therapeutic effect of cardiac glycosides for congestive heart failure lies in their reversible inhibition on Na+, K+-ATPase located in human myocardium. Several steroid-like compounds containing a core structure similar to cardiac glycosides have been found in many Chinese herbs and medicinal animal products conventionally used to promote blood circulation. They are putatively responsible for the therapeutic effect of those medicinal products via the same mechanism of inhibiting Na+, K+-ATPase. Inhibitory potency on Na+, K+-ATPase by ginsenosides, one of the identified steroid-like compounds, is significantly affected by sugar attachment that might cause steric hindrance of their binding to Na+, K+-ATPase. Ginsenosides with sugar moieties attached only to the C-3 position of the steroid-like structure, equivalent to the sugar position in cardiac glycosides, substantially inhibit Na+, K+-ATPase. However, their inhibitory potency is abolished when sugar moieties are linked to the C-6 or C-20 position of the steroid-like structure. In contrast, no appreciable contents of steroid-like compounds are found in danshen, a well-known Chinese herb traditionally regarded as an effective medicine promoting blood circulation. Instead, magnesium lithospermate B (MLB), the major soluble ingredient in danshen, is assumed to be responsible for the therapeutic effect by inhibiting Na+, K+-ATPase in a manner comparable to cardiac glycosides. Neuroprotective effects of cardiac glycosides, ginsenosides and MLB against ischemic stroke were accordingly observed in a cortical brain slice-based assay model. Whether the neuroprotection is also triggered by inhibition of Na+, K+-ATPase remains to be investigated. Molecular modeling suggests that cardiac glycosides, ginsenosides and MLB presumably bind to the same extracellular pocket of the Na+, K+-ATPase alpha subunit.

Design and characterization of the first peptidomimetic molecule that prevents acidification-induced closure of cardiac gap junctions

PubMed Central

Verma, Vandana; Larsen, Bjarne Due; Coombs, Wanda; Lin, Xianming; Sarrou, Eliana; Taffet, Steven M.; Delmar, Mario

2010-01-01

Background Gap junctions are potential targets for pharmacological intervention. We have previously developed a series of peptide sequences that prevent closure of Cx43 channels, bind to cardiac Cx43 and prevent acidification-induced uncoupling of cardiac gap junctions. Objective We aimed to identify and validate the minimum core active structure in peptides containing an RR-N/Q-Y motif. Based on that information, we sought to generate a peptidomimetic molecule that acts on the chemical regulation of Cx43 channels. Methods Experiments were based on a combination of biochemical, spectroscopic and electrophysiological techniques, as well as molecular modeling of active pharmacophores with Cx43 activity. Results Molecular modeling analysis indicated that the functional elements of the side chains in the motif RRXY form a triangular structure. Experimental data revealed that compounds containing such a structure bind to Cx43 and prevent Cx43 chemical gating. These results provided us with the first platform for drug design targeted to the carboxyl terminal of Cx43. Using that platform, we designed and validated a peptidomimetic compound (ZP2519; molecular weight 619 Da) that prevented octanol-induced uncoupling of Cx43 channels, and pH gating of cardiac gap junctions. Conclusion Structure-based drug design can be applied to the development of pharmacophores that act directly on Cx43. Small molecules containing these pharmacophores can serve as tools to determine the role of gap junction regulation in the control of cardiac rhythm. Future studies will determine whether these compounds can function as pharmacological agents for the treatment of a selected subset of cardiac arrhythmias. PMID:20601149

Orientation of Myosin Binding Protein C in the Cardiac Muscle Sarcomere Determined by Domain-Specific Immuno-EM

PubMed Central

Lee, Kyounghwan; Harris, Samantha P.; Sadayappan, Sakthivel; Craig, Roger

2014-01-01

Myosin binding protein-C is a thick filament protein of vertebrate striated muscle. The cardiac isoform (cMyBP-C) is essential for normal cardiac function, and mutations in cMyBP-C cause cardiac muscle disease. The rod-shaped molecule is composed primarily of 11 immunoglobulin- or fibronectin-like domains, and is located at 9 sites, 43 nm apart, in each half of the A-band. To understand how cMyBP-C functions, it is important to know its structural organization in the sarcomere, as this will affect its ability to interact with other sarcomeric proteins. Several models have been proposed, in which cMyBP-C wraps around, extends radially from, or runs axially along the thick filament. Our goal was to define cMyBP-C orientation by determining the relative axial positions of different cMyBP-C domains. Immuno-electron microscopy was performed using mouse cardiac myofibrils labeled with antibodies specific to the N- and C-terminal domains and to the middle of cMyBP-C. Antibodies to all regions of the molecule, except the C-terminus, labeled at the same nine axial positions in each half A-band, consistent with a circumferential and/or radial rather than an axial orientation of the bulk of the molecule. The C-terminal antibody stripes were slightly displaced axially, demonstrating an axial orientation of the C-terminal 3 domains, with the C-terminus closer to the M-line. These results, combined with previous studies, suggest that the C-terminal domains of cMyBP-C run along the thick filament surface, while the N-terminus extends towards neighboring thin filaments. This organization provides a structural framework for understanding cMyBP-C’s modulation of cardiac muscle contraction. PMID:25451032

Cardiac Endothelial Cell Transcriptome.

PubMed

Lother, Achim; Bergemann, Stella; Deng, Lisa; Moser, Martin; Bode, Christoph; Hein, Lutz

2018-03-01

Endothelial cells (ECs) are a highly specialized cell type with marked diversity between different organs or vascular beds. Cardiac ECs are an important player in cardiac physiology and pathophysiology but are not sufficiently characterized yet. Thus, the aim of the present study was to analyze the cardiac EC transcriptome. We applied fluorescence-assisted cell sorting to isolate pure ECs from adult mouse hearts. RNAseq revealed 1288 genes predominantly expressed in cardiac ECs versus heart tissue including several transcription factors. We found an overrepresentation of corresponding transcription factor binding motifs within the promotor region of EC-enriched genes, suggesting that they control the EC transcriptome. Cardiac ECs exhibit a distinct gene expression profile when compared with renal, cerebral, or pulmonary ECs. For example, we found the Meox2 / Tcf15, Fabp4 , and Cd36 signaling cascade higher expressed in cardiac ECs which is a key regulator of fatty acid uptake and involved in the development of atherosclerosis. The results from this study provide a comprehensive resource of gene expression and transcriptional control in cardiac ECs. The cardiac EC transcriptome exhibits distinct differences in gene expression compared with other cardiac cell types and ECs from other organs. We identified new candidate genes that have not been investigated in ECs yet as promising targets for future evaluation. © 2018 American Heart Association, Inc.

Translational neurocardiology: preclinical models and cardioneural integrative aspects.

PubMed

Ardell, J L; Andresen, M C; Armour, J A; Billman, G E; Chen, P-S; Foreman, R D; Herring, N; O'Leary, D S; Sabbah, H N; Schultz, H D; Sunagawa, K; Zucker, I H

2016-07-15

Neuronal elements distributed throughout the cardiac nervous system, from the level of the insular cortex to the intrinsic cardiac nervous system, are in constant communication with one another to ensure that cardiac output matches the dynamic process of regional blood flow demand. Neural elements in their various 'levels' become differentially recruited in the transduction of sensory inputs arising from the heart, major vessels, other visceral organs and somatic structures to optimize neuronal coordination of regional cardiac function. This White Paper will review the relevant aspects of the structural and functional organization for autonomic control of the heart in normal conditions, how these systems remodel/adapt during cardiac disease, and finally how such knowledge can be leveraged in the evolving realm of autonomic regulation therapy for cardiac therapeutics. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

Real-time myocardium segmentation for the assessment of cardiac function variation

NASA Astrophysics Data System (ADS)

Zoehrer, Fabian; Huellebrand, Markus; Chitiboi, Teodora; Oechtering, Thekla; Sieren, Malte; Frahm, Jens; Hahn, Horst K.; Hennemuth, Anja

2017-03-01

Recent developments in MRI enable the acquisition of image sequences with high spatio-temporal resolution. Cardiac motion can be captured without gating and triggering. Image size and contrast relations differ from conventional cardiac MRI cine sequences requiring new adapted analysis methods. We suggest a novel segmentation approach utilizing contrast invariant polar scanning techniques. It has been tested with 20 datasets of arrhythmia patients. The results do not differ significantly more between automatic and manual segmentations than between observers. This indicates that the presented solution could enable clinical applications of real-time MRI for the examination of arrhythmic cardiac motion in the future.

Understanding the in vivo uptake kinetics of a phosphatidylethanolamine-binding agent (99m)Tc-Duramycin.

PubMed

Audi, Said; Li, Zhixin; Capacete, Joseph; Liu, Yu; Fang, Wei; Shu, Laura G; Zhao, Ming

2012-08-01

(99m)Tc-Duramycin is a peptide-based molecular probe that binds specifically to phosphatidylethanolamine (PE). The goal was to characterize the kinetics of molecular interactions between (99m)Tc-Duramycin and the target tissue. High level of accessible PE is induced in cardiac tissues by myocardial ischemia (30 min) and reperfusion (120 min) in Sprague-Dawley rats. Target binding and biodistribution of (99m)Tc-duramycin were captured using SPECT/CT. To quantify the binding kinetics, the presence of radioactivity in ischemic versus normal cardiac tissues was measured by gamma counting at 3, 10, 20, 60 and 180 min after injection. A partially inactivated form of (99m)Tc-Duramycin was analyzed in the same fashion. A compartment model was developed to quantify the uptake kinetics of (99m)Tc-Duramycin in normal and ischemic myocardial tissue. (99m)Tc-duramycin binds avidly to the damaged tissue with a high target-to-background radio. Compartment modeling shows that accessibility of binding sites in myocardial tissue to (99m)Tc-Duramycin is not a limiting factor and the rate constant of target binding in the target tissue is at 2.2 ml/nmol/min/g. The number of available binding sites for (99m)Tc-Duramycin in ischemic myocardium was estimated at 0.14 nmol/g. Covalent modification of D15 resulted in a 9-fold reduction in binding affinity. (99m)Tc-Duramycin accumulates avidly in target tissues in a PE-dependent fashion. Model results reflect an efficient uptake mechanism, consistent with the low molecular weight of the radiopharmaceutical and the relatively high density of available binding sites. These data help better define the imaging utilities of (99m)Tc-Duramycin as a novel PE-binding agent. Copyright © 2012 Elsevier Inc. All rights reserved.

Development of cardiac parasympathetic neurons, glial cells, and regional cholinergic innervation of the mouse heart.

PubMed

Fregoso, S P; Hoover, D B

2012-09-27

Very little is known about the development of cardiac parasympathetic ganglia and cholinergic innervation of the mouse heart. Accordingly, we evaluated the growth of cholinergic neurons and nerve fibers in mouse hearts from embryonic day 18.5 (E18.5) through postnatal day 21(P21). Cholinergic perikarya and varicose nerve fibers were identified in paraffin sections immunostained for the vesicular acetylcholine transporter (VAChT). Satellite cells and Schwann cells in adjacent sections were identified by immunostaining for S100β calcium binding protein (S100) and brain-fatty acid binding protein (B-FABP). We found that cardiac ganglia had formed in close association to the atria and cholinergic innervation of the atrioventricular junction had already begun by E18.5. However, most cholinergic innervation of the heart, including the sinoatrial node, developed postnatally (P0.5-P21) along with a doubling of the cross-sectional area of cholinergic perikarya. Satellite cells were present throughout neonatal cardiac ganglia and expressed primarily B-FABP. As they became more mature at P21, satellite cells stained strongly for both B-FABP and S100. Satellite cells appeared to surround most cardiac parasympathetic neurons, even in neonatal hearts. Mature Schwann cells, identified by morphology and strong staining for S100, were already present at E18.5 in atrial regions that receive cholinergic innervation at later developmental times. The abundance and distribution of S100-positive Schwann cells increased postnatally along with nerve density. While S100 staining of cardiac Schwann cells was maintained in P21 and older mice, Schwann cells did not show B-FABP staining at these times. Parallel development of satellite cells and cholinergic perikarya in the cardiac ganglia and the increase in abundance of Schwann cells and varicose cholinergic nerve fibers in the atria suggest that neuronal-glial interactions could be important for development of the parasympathetic nervous system in the heart. Copyright © 2012 IBRO. Published by Elsevier Ltd. All rights reserved.

Surviving the infarct: A profile of cardiac myosin binding protein-C pathogenicity, diagnostic utility, and proteomics in the ischemic myocardium.

PubMed

Lynch, Thomas L; Sadayappan, Sakthivel

2014-08-01

Cardiac myosin binding protein-C (cMyBP-C) is a regulatory protein of the contractile apparatus within the cardiac sarcomere. Ischemic injury to the heart during myocardial infarction (MI) results in the cleavage of cMyBP-C in a phosphorylation-dependent manner and release of an N-terminal fragment (C0C1f) into the circulation. C0C1f has been shown to be pathogenic within cardiac tissue, leading to the development of heart failure. Based on its high levels and early release into the circulation post-MI, C0C1f may serve as a novel biomarker for diagnosing MI more effectively than current clinically used biomarkers. Over time, circulating C0C1f could trigger an autoimmune response leading to myocarditis and progressive cardiac dysfunction. Given the importance of cMyBP-C phosphorylation state in the context of proteolytic cleavage and release into the circulation post-MI, understanding the posttranslational modifications (PTMs) of cMyBP-C would help in further elucidating the role of this protein in health and disease. Accordingly, recent studies have implemented the latest proteomics approaches to define the PTMs of cMyBP-C. The use of such proteomics assays may provide accurate quantitation of the levels of cMyBP-C in the circulation following MI, which could, in turn, demonstrate the efficacy of using plasma cMyBP-C as a cardiac-specific early biomarker of MI. In this review, we define the pathogenic and potential immunogenic effects of C0C1f on cardiac function in the post-MI heart. We also discuss the most advanced proteomics approaches now used to determine cMyBP-C PTMs with the aim of validating C0C1f as an early biomarker of MI. © The Authors PROTEOMICS - Clinical Applications Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Genotype-phenotype correlation between the cardiac myosin binding protein C mutation A31P and hypertrophic cardiomyopathy in a cohort of Maine Coon cats: a longitudinal study.

PubMed

Granström, S; Godiksen, M T N; Christiansen, M; Pipper, C B; Martinussen, T; Møgelvang, R; Søgaard, P; Willesen, J L; Koch, J

2015-12-01

A missense mutation (A31P) in the cardiac myosin binding protein C gene has been associated with hypertrophic cardiomyopathy (HCM) in Maine Coon cats. The aim of this study was to investigate the effect of A31P on development of HCM, myocardial diastolic dysfunction detected by color tissue Doppler imaging and occurrence of cardiac death during longitudinal follow-up in a cohort of Maine Coon cats. The original cohort comprised 282 cats (158 of wild-type genotype, 99 heterozygous for A31P and 25 homozygous for A31P). Prospective longitudinal study including echocardiography and registration of survival. The median age at the initial examination was 1.7 years (range, 0.8-9.2 years) and 6.4% (18/282) of the cats were diagnosed with HCM. One hundred sixty-five cats were eligible for echocardiographic re-examination, and during an average follow-up period of 2.7 years an additional 6.7% (11/165) of the cats developed HCM. Survival data could be obtained for 262 of the cats originally included, and among these 9.2% (24/262) died of causes that met the study criteria for cardiac death. In the homozygous group 80% (20/25) of cats included were diagnosed with HCM and 48% (12/25) suffered cardiac death during follow-up. These results corresponded to a significantly higher risk for cats homozygous for A31P to develop HCM (p<0.001) and die from cardiac-related causes compared with both other genotypes (p<0.001). Homozygosity for A31P was associated with a high penetrance of HCM and a substantial risk for cardiac death in the study population. Copyright © 2015 Elsevier B.V. All rights reserved.

C-Terminal β9-Strand of the Cyclic Nucleotide-Binding Homology Domain Stabilizes Activated States of Kv11.1 Channels

PubMed Central

Ng, Chai Ann; Ke, Ying; Perry, Matthew D.; Tan, Peter S.; Hill, Adam P.; Vandenberg, Jamie I.

2013-01-01

Kv11.1 potassium channels are important for regulation of the normal rhythm of the heartbeat. Reduced activity of Kv11.1 channels causes long QT syndrome type 2, a disorder that increases the risk of cardiac arrhythmias and sudden cardiac arrest. Kv11.1 channels are members of the KCNH subfamily of voltage-gated K+ channels. However, they also share many similarities with the cyclic nucleotide gated ion channel family, including having a cyclic nucleotide-binding homology (cNBH) domain. Kv11.1 channels, however, are not directly regulated by cyclic nucleotides. Recently, crystal structures of the cNBH domain from mEAG and zELK channels, both members of the KCNH family of voltage-gated potassium channels, revealed that a C-terminal β9-strand in the cNBH domain occupied the putative cyclic nucleotide-binding site thereby precluding binding of cyclic nucleotides. Here we show that mutations to residues in the β9-strand affect the stability of the open state relative to the closed state of Kv11.1 channels. We also show that disrupting the structure of the β9-strand reduces the stability of the inactivated state relative to the open state. Clinical mutations located in this β9-strand result in reduced trafficking efficiency, which suggests that binding of the C-terminal β9-strand to the putative cyclic nucleotide-binding pocket is also important for assembly and trafficking of Kv11.1 channels. PMID:24204727

Effects of egg-adaptation on receptor-binding and antigenic properties of recent influenza A (H3N2) vaccine viruses.

PubMed

Parker, Lauren; Wharton, Stephen A; Martin, Stephen R; Cross, Karen; Lin, Yipu; Liu, Yan; Feizi, Ten; Daniels, Rodney S; McCauley, John W

2016-06-01

Influenza A virus (subtype H3N2) causes seasonal human influenza and is included as a component of influenza vaccines. The majority of vaccine viruses are isolated and propagated in eggs, which commonly results in amino acid substitutions in the haemagglutinin (HA) glycoprotein. These substitutions can affect virus receptor-binding and alter virus antigenicity, thereby, obfuscating the choice of egg-propagated viruses for development into candidate vaccine viruses. To evaluate the effects of egg-adaptive substitutions seen in H3N2 vaccine viruses on sialic acid receptor-binding, we carried out quantitative measurement of virus receptor-binding using surface biolayer interferometry with haemagglutination inhibition (HI) assays to correlate changes in receptor avidity with antigenic properties. Included in these studies was a panel of H3N2 viruses generated by reverse genetics containing substitutions seen in recent egg-propagated vaccine viruses and corresponding cell culture-propagated wild-type viruses. These assays provide a quantitative approach to investigating the importance of individual amino acid substitutions in influenza receptor-binding. Results show that viruses with egg-adaptive HA substitutions R156Q, S219Y, and I226N, have increased binding avidity to α2,3-linked receptor-analogues and decreased binding avidity to α2,6-linked receptor-analogues. No measurable binding was detected for the viruses with amino acid substitution combination 156Q+219Y and receptor-binding increased in viruses where egg-adaptation mutations were introduced into cell culture-propagated virus. Substitutions at positions 156 and 190 appeared to be primarily responsible for low reactivity in HI assays with post-infection ferret antisera raised against 2012-2013 season H3N2 viruses. Egg-adaptive substitutions at position 186 caused substantial differences in binding avidity with an insignificant effect on antigenicity.

Myocardin-related transcription factors are required for cardiac development and function

PubMed Central

Mokalled, Mayssa H.; Carroll, Kelli J.; Cenik, Bercin K.; Chen, Beibei; Liu, Ning; Olson, Eric N.; Bassel-Duby, Rhonda

2016-01-01

Myocardin-Related Transcription Factors A and B (MRTF-A and MRTF-B) are highly homologous proteins that function as powerful coactivators of serum response factor (SRF), a ubiquitously expressed transcription factor essential for cardiac development. The SRF/MRTF complex binds to CArG boxes found in the control regions of genes that regulate cytoskeletal dynamics and muscle contraction, among other processes. While SRF is required for heart development and function, the role of MRTFs in the developing or adult heart has not been explored. Through cardiac-specific deletion of MRTF alleles in mice, we show that either MRTF-A or MRTF-B is dispensable for cardiac development and function, whereas deletion of both MRTF-A and MRTF-B causes a spectrum of structural and functional cardiac abnormalities. Defects observed in MRTF-A/B null mice ranged from reduced cardiac contractility and adult onset heart failure to neonatal lethality accompanied by sarcomere disarray. RNA-seq analysis on neonatal hearts identified the most altered pathways in MRTF double knockout hearts as being involved in cytoskeletal organization. Together, these findings demonstrate redundant but essential roles of the MRTFs in maintenance of cardiac structure and function and as indispensible links in cardiac cytoskeletal gene regulatory networks. PMID:26386146

Cardiovascular and haematological responses of Atlantic cod (Gadus morhua) to acute temperature increase.

PubMed

Gollock, M J; Currie, S; Petersen, L H; Gamperl, A K

2006-08-01

For fish to survive large acute temperature increases (i.e. >10.0 degrees C) that may bring them close to their critical thermal maximum (CTM), oxygen uptake at the gills and distribution by the cardiovascular system must increase to match tissue oxygen demand. To examine the effects of an acute temperature increase ( approximately 1.7 degrees C h(-1) to CTM) on the cardiorespiratory physiology of Atlantic cod, we (1) carried out respirometry on 10.0 degrees C acclimated fish, while simultaneously measuring in vivo cardiac parameters using Transonic probes, and (2) constructed in vitro oxygen binding curves on whole blood from 7.0 degrees C acclimated cod at a range of temperatures. Both cardiac output (Q) and heart rate (fh) increased until near the fish's CTM (22.2+/-0.2 degrees C), and then declined rapidly. Q(10) values for Q and fh were 2.48 and 2.12, respectively, and increases in both parameters were tightly correlated with O(2) consumption. The haemoglobin (Hb)-oxygen binding curve at 24.0 degrees C showed pronounced downward and rightward shifts compared to 20.0 degrees C and 7.0 degrees C, indicating that both binding capacity and affinity decreased. Further, Hb levels were lower at 24.0 degrees C than at 20.0 degrees C and 7.0 degrees C. This was likely to be due to cell swelling, as electrophoresis of Hb samples did not suggest protein denaturation, and at 24.0 degrees C Hb samples showed peak absorbance at the expected wavelength (540 nm). Our results show that cardiac function is unlikely to limit metabolic rate in Atlantic cod from Newfoundland until close to their CTM, and we suggest that decreased blood oxygen binding capacity may contribute to the plateau in oxygen consumption.

Msx1 and Msx2 are functional interacting partners of T-box factors in the regulation of Connexin43.

PubMed

Boogerd, Kees-Jan; Wong, L Y Elaine; Christoffels, Vincent M; Klarenbeek, Meinke; Ruijter, Jan M; Moorman, Antoon F M; Barnett, Phil

2008-06-01

T-box factors Tbx2 and Tbx3 play key roles in the development of the cardiac conduction system, atrioventricular canal, and outflow tract of the heart. They regulate the gap-junction-encoding gene Connexin43 (Cx43) and other genes critical for heart development and function. Discovering protein partners of Tbx2 and Tbx3 will shed light on the mechanisms by which these factors regulate these gene programs. Employing an yeast 2-hybrid screen and subsequent in vitro pull-down experiments we demonstrate that muscle segment homeobox genes Msx1 and Msx2 are able to bind the cardiac T-box proteins Tbx2, Tbx3, and Tbx5. This interaction, as that of the related Nkx2.5 protein, is supported by the T-box and homeodomain alone. Overlapping spatiotemporal expression patterns of Msx1 and Msx2 together with the T-box genes during cardiac development in mouse and chicken underscore the biological significance of this interaction. We demonstrate that Msx proteins together with Tbx2 and Tbx3 suppress Cx43 promoter activity and down regulate Cx43 gene activity in a rat heart-derived cell line. Using chromatin immunoprecipitation analysis we demonstrate that Msx1 can bind the Cx43 promoter at a conserved binding site located in close proximity to a previously defined T-box binding site, and that the activity of Msx proteins on this promoter appears dependent in the presence of Tbx3. Msx1 and Msx2 can function in concert with the T-box proteins to suppress Cx43 and other working myocardial genes.

Performance evaluation of GPU parallelization, space-time adaptive algorithms, and their combination for simulating cardiac electrophysiology.

PubMed

Sachetto Oliveira, Rafael; Martins Rocha, Bernardo; Burgarelli, Denise; Meira, Wagner; Constantinides, Christakis; Weber Dos Santos, Rodrigo

2018-02-01

The use of computer models as a tool for the study and understanding of the complex phenomena of cardiac electrophysiology has attained increased importance nowadays. At the same time, the increased complexity of the biophysical processes translates into complex computational and mathematical models. To speed up cardiac simulations and to allow more precise and realistic uses, 2 different techniques have been traditionally exploited: parallel computing and sophisticated numerical methods. In this work, we combine a modern parallel computing technique based on multicore and graphics processing units (GPUs) and a sophisticated numerical method based on a new space-time adaptive algorithm. We evaluate each technique alone and in different combinations: multicore and GPU, multicore and GPU and space adaptivity, multicore and GPU and space adaptivity and time adaptivity. All the techniques and combinations were evaluated under different scenarios: 3D simulations on slabs, 3D simulations on a ventricular mouse mesh, ie, complex geometry, sinus-rhythm, and arrhythmic conditions. Our results suggest that multicore and GPU accelerate the simulations by an approximate factor of 33×, whereas the speedups attained by the space-time adaptive algorithms were approximately 48. Nevertheless, by combining all the techniques, we obtained speedups that ranged between 165 and 498. The tested methods were able to reduce the execution time of a simulation by more than 498× for a complex cellular model in a slab geometry and by 165× in a realistic heart geometry simulating spiral waves. The proposed methods will allow faster and more realistic simulations in a feasible time with no significant loss of accuracy. Copyright © 2017 John Wiley & Sons, Ltd.

Metabolic adaptation to chronic hypoxia in cardiac mitochondria.

PubMed

Heather, Lisa C; Cole, Mark A; Tan, Jun-Jie; Ambrose, Lucy J A; Pope, Simon; Abd-Jamil, Amira H; Carter, Emma E; Dodd, Michael S; Yeoh, Kar Kheng; Schofield, Christopher J; Clarke, Kieran

2012-05-01

Chronic hypoxia decreases cardiomyocyte respiration, yet the mitochondrial mechanisms remain largely unknown. We investigated the mitochondrial metabolic pathways and enzymes that were decreased following in vivo hypoxia, and questioned whether hypoxic adaptation was protective for the mitochondria. Wistar rats were housed in hypoxia (7 days acclimatisation and 14 days at 11% oxygen), while control rats were housed in normoxia. Chronic exposure to physiological hypoxia increased haematocrit and cardiac vascular endothelial growth factor, in the absence of weight loss and changes in cardiac mass. In both subsarcolemmal (SSM) and interfibrillar (IFM) mitochondria isolated from hypoxic hearts, state 3 respiration rates with fatty acid were decreased by 17-18%, and with pyruvate were decreased by 29-15%, respectively. State 3 respiration rates with electron transport chain (ETC) substrates were decreased only in hypoxic SSM, not in hypoxic IFM. SSM from hypoxic hearts had decreased activities of ETC complexes I, II and IV, which were associated with decreased reactive oxygen species generation and protection against mitochondrial permeability transition pore (MPTP) opening. In contrast, IFM from hypoxic hearts had decreased activity of the Krebs cycle enzyme, aconitase, which did not modify ROS production or MPTP opening. In conclusion, cardiac mitochondrial respiration was decreased following chronic hypoxia, associated with downregulation of different pathways in the two mitochondrial populations, determined by their subcellular location. Hypoxic adaptation was not deleterious for the mitochondria, in fact, SSM acquired increased protection against oxidative damage under the oxygen-limited conditions.

Interaction between two adapter proteins, PAG and EBP50: a possible link between membrane rafts and actin cytoskeleton.

PubMed

Brdicková, N; Brdicka, T; Andera, L; Spicka, J; Angelisová, P; Milgram, S L; Horejsí, V

2001-10-26

Phosphoprotein associated with GEMs (PAG), also known as Csk-binding protein (Cbp), is a broadly expressed palmitoylated transmembrane adapter protein found in membrane rafts, also called GEMs (glycosphingolipid-enriched membrane microdomains). PAG is known to bind and activate the essential regulator of Src-family kinases, cytoplasmic protein tyrosine kinase Csk. In the present study we used the yeast 2-hybrid system to search for additional proteins which might bind to PAG. We have identified the abundant cytoplasmic adapter protein EBP50 (ezrin/radixin/moesin (ERM)-binding phosphoprotein of 50 kDa), also known as NHERF (Na(+)/H(+) exchanger regulatory factor), as a specific PAG-binding partner. The interaction involves the C-terminal sequence (TRL) of PAG and N-terminal PDZ domain(s) of EBP50. As EBP50 is known to interact via its C-terminal domain with the ERM-family proteins, which in turn bind to actin cytoskeleton, the PAG-EBP50 interaction may be important for connecting membrane rafts to the actin cytoskeleton.

Intrinsic disorder mediates the diverse regulatory functions of the Cdk inhibitor p21

PubMed Central

Wang, Yuefeng; Fisher, John C.; Mathew, Rose; Ou, Li; Otieno, Steve; Sublett, Jack; Xiao, Limin; Chen, Jianhan; Roussel, Martine F.; Kriwacki, Richard W.

2011-01-01

Traditionally, well-defined three-dimensional structure was thought to be essential for protein function. However, myriad biological functions are performed by highly dynamic, intrinsically disordered proteins (IDPs). IDPs often fold upon binding their biological targets and frequently exhibit “binding diversity” by targeting multiple ligands. We sought to understand the physical basis of IDP binding diversity and herein report that the cyclin-dependent kinase (Cdk) inhibitor, p21Cip1, adaptively binds to and inhibits the various Cdk/cyclin complexes that regulate eukaryotic cell division. Based on results from NMR spectroscopy, and biochemical and cellular assays, we show that structural adaptability of a helical sub-domain within p21 termed LH enables two other sub-domains termed D1 and D2 to specifically bind conserved surface features of the cyclin and Cdk subunits, respectively, within otherwise structurally distinct Cdk/cyclin complexes. Adaptive folding upon binding is likely to mediate the diverse biological functions of the thousands of IDPs present in eukaryotes. PMID:21358637

MURC, a Muscle-Restricted Coiled-Coil Protein That Modulates the Rho/ROCK Pathway, Induces Cardiac Dysfunction and Conduction Disturbance▿

PubMed Central

Ogata, Takehiro; Ueyama, Tomomi; Isodono, Koji; Tagawa, Masashi; Takehara, Naofumi; Kawashima, Tsuneaki; Harada, Koichiro; Takahashi, Tomosaburo; Shioi, Tetsuo; Matsubara, Hiroaki; Oh, Hidemasa

2008-01-01

We identified a novel muscle-restricted putative coiled-coil protein, MURC, which is evolutionarily conserved from frog to human. MURC was localized to the cytoplasm with accumulation in the Z-line of the sarcomere in the murine adult heart. MURC mRNA expression in the heart increased during the developmental process from the embryonic stage to adulthood. In response to pressure overload, MURC mRNA expression increased in the hypertrophied heart. Using the yeast two-hybrid system, we identified the serum deprivation response (SDPR) protein, a phosphatidylserine-binding protein, as a MURC-binding protein. MURC induced activation of the RhoA/ROCK pathway, which modulated serum response factor-mediated atrial natriuretic peptide (ANP) expression and myofibrillar organization. SDPR augmented MURC-induced transactivation of the ANP promoter in cardiomyocytes, and RNA interference of SDPR attenuated the action of MURC on the ANP promoter. Transgenic mice expressing cardiac-specific MURC (Tg-MURC) exhibited cardiac contractile dysfunction and atrioventricular (AV) conduction disturbances with atrial chamber enlargement, reduced thickness of the ventricular wall, and interstitial fibrosis. Spontaneous episodes of atrial fibrillation and AV block were observed in Tg-MURC mice. These findings indicate that MURC modulates RhoA signaling and that MURC plays an important role in the development of cardiac dysfunction and conduction disturbance with increased vulnerability to atrial arrhythmias. PMID:18332105

MURC, a muscle-restricted coiled-coil protein that modulates the Rho/ROCK pathway, induces cardiac dysfunction and conduction disturbance.

PubMed

Ogata, Takehiro; Ueyama, Tomomi; Isodono, Koji; Tagawa, Masashi; Takehara, Naofumi; Kawashima, Tsuneaki; Harada, Koichiro; Takahashi, Tomosaburo; Shioi, Tetsuo; Matsubara, Hiroaki; Oh, Hidemasa

2008-05-01

We identified a novel muscle-restricted putative coiled-coil protein, MURC, which is evolutionarily conserved from frog to human. MURC was localized to the cytoplasm with accumulation in the Z-line of the sarcomere in the murine adult heart. MURC mRNA expression in the heart increased during the developmental process from the embryonic stage to adulthood. In response to pressure overload, MURC mRNA expression increased in the hypertrophied heart. Using the yeast two-hybrid system, we identified the serum deprivation response (SDPR) protein, a phosphatidylserine-binding protein, as a MURC-binding protein. MURC induced activation of the RhoA/ROCK pathway, which modulated serum response factor-mediated atrial natriuretic peptide (ANP) expression and myofibrillar organization. SDPR augmented MURC-induced transactivation of the ANP promoter in cardiomyocytes, and RNA interference of SDPR attenuated the action of MURC on the ANP promoter. Transgenic mice expressing cardiac-specific MURC (Tg-MURC) exhibited cardiac contractile dysfunction and atrioventricular (AV) conduction disturbances with atrial chamber enlargement, reduced thickness of the ventricular wall, and interstitial fibrosis. Spontaneous episodes of atrial fibrillation and AV block were observed in Tg-MURC mice. These findings indicate that MURC modulates RhoA signaling and that MURC plays an important role in the development of cardiac dysfunction and conduction disturbance with increased vulnerability to atrial arrhythmias.

Measurements of nonlinear Hall-driven reconnection in the reversed field pinch

NASA Astrophysics Data System (ADS)

Tharp, Timothy D.

Complex organisms are able to develop because of the complex regulatory systems that control their gene expression. The first step in this regulation, transcription initiation, is controlled by transcription factors. Transcription factors are modular proteins composed of two distinct domains, the DNA binding domain and the regulatory domain. These molecules are involved in a plethora of important biological processes including embryogenesis, development, cell health, and cancer. Tissue enriched transcription factors Nkx-2.5 and Gata4 are involved in cardiac development and cardiac health. In this thesis the DNA binding specificity of Nkx-2.5 will be analyzed using a high throughput double stranded DNA platform called Cognate Site Identifier (CSI) arrays (Chapter 2). The full DNA binding specificity of Nkx-2.5 and Nkx-2.5 mutants will be visualized using Sequence Specificity Landscapes (SSLs). In Chapter 3, the definition of binding specificity will be investigated by evaluating a number of different DNA binding folds by CSI and SSLs. CSI and SSLs will also be used to evaluate different pyrrole/imidazole hairpin polyamides in order to better characterize these small molecule DNA binding domains. CSI and SSL data will be applied to the genome in order to explain the biological function an artificial transcription factor. Chapter 4 will discuss the mechanism of nonspecific DNA binding. The historical means of predicting DNA binding will be challenged by utilizing high throughput experiments. The effect of salt concentration on both specific and nonspecific binding will also be investigated. Finally, in Chapter 5, a generation of Protein DNA Dimerizer will be discussed. A PDD that regulates transcription on genomic DNA by binding cooperatively with the heart IF Gata4 will be characterized. These studies provide understanding of, and a means to control, how transcription factors sample the endless sea of DNA in the genome in order to regulate gene expression with such wonderful specificity.

Identification of genes regulated during mechanical load-induced cardiac hypertrophy

NASA Technical Reports Server (NTRS)

Johnatty, S. E.; Dyck, J. R.; Michael, L. H.; Olson, E. N.; Abdellatif, M.; Schneider, M. (Principal Investigator)

2000-01-01

Cardiac hypertrophy is associated with both adaptive and adverse changes in gene expression. To identify genes regulated by pressure overload, we performed suppressive subtractive hybridization between cDNA from the hearts of aortic-banded (7-day) and sham-operated mice. In parallel, we performed a subtraction between an adult and a neonatal heart, for the purpose of comparing different forms of cardiac hypertrophy. Sequencing more than 100 clones led to the identification of an array of functionally known (70%) and unknown genes (30%) that are upregulated during cardiac growth. At least nine of those genes were preferentially expressed in both the neonatal and pressure over-load hearts alike. Using Northern blot analysis to investigate whether some of the identified genes were upregulated in the load-independent calcineurin-induced cardiac hypertrophy mouse model, revealed its incomplete similarity with the former models of cardiac growth. Copyright 2000 Academic Press.

Cardiac Expression of ms1/STARS, a Novel Gene Involved in Cardiac Development and Disease, Is Regulated by GATA4

PubMed Central

Kobayashi, Satoru; Peterson, Richard E.; He, Aibin; Motterle, Anna; Samani, Nilesh J.; Menick, Donald R.; Pu, William T.; Liang, Qiangrong

2012-01-01

Ms1/STARS is a novel muscle-specific actin-binding protein that specifically modulates the myocardin-related transcription factor (MRTF)-serum response factor (SRF) regulatory axis within striated muscle. This ms1/STARS-dependent regulatory axis is of central importance within the cardiac gene regulatory network and has been implicated in cardiac development and postnatal cardiac function/homeostasis. The dysregulation of ms1/STARS is associated with and causative of pathological cardiac phenotypes, including cardiac hypertrophy and cardiomyopathy. In order to gain an understanding of the mechanisms governing ms1/STARS expression in the heart, we have coupled a comparative genomic in silico analysis with reporter, gain-of-function, and loss-of-function approaches. Through this integrated analysis, we have identified three evolutionarily conserved regions (ECRs), α, SINA, and DINA, that act as cis-regulatory modules and confer differential cardiac cell-specific activity. Two of these ECRs, α and DINA, displayed distinct regulatory sensitivity to the core cardiac transcription factor GATA4. Overall, our results demonstrate that within embryonic, neonatal, and adult hearts, GATA4 represses ms1/STARS expression with the pathologically associated depletion of GATA4 (type 1/type 2 diabetic models), resulting in ms1/STARS upregulation. This GATA4-dependent repression of ms1/STARS expression has major implications for MRTF-SRF signaling in the context of cardiac development and disease. PMID:22431517

Genome analysis and signature discovery for diving and sensory properties of the endangered Chinese alligator

PubMed Central

Wan, Qiu-Hong; Pan, Sheng-Kai; Hu, Li; Zhu, Ying; Xu, Peng-Wei; Xia, Jin-Quan; Chen, Hui; He, Gen-Yun; He, Jing; Ni, Xiao-Wei; Hou, Hao-Long; Liao, Sheng-Guang; Yang, Hai-Qiong; Chen, Ying; Gao, Shu-Kun; Ge, Yun-Fa; Cao, Chang-Chang; Li, Peng-Fei; Fang, Li-Ming; Liao, Li; Zhang, Shu; Wang, Meng-Zhen; Dong, Wei; Fang, Sheng-Guo

2013-01-01

Crocodilians are diving reptiles that can hold their breath under water for long periods of time and are crepuscular animals with excellent sensory abilities. They comprise a sister lineage of birds and have no sex chromosome. Here we report the genome sequence of the endangered Chinese alligator (Alligator sinensis) and describe its unique features. The next-generation sequencing generated 314 Gb of raw sequence, yielding a genome size of 2.3 Gb. A total of 22 200 genes were predicted in Alligator sinensis using a de novo, homology- and RNA-based combined model. The genetic basis of long-diving behavior includes duplication of the bicarbonate-binding hemoglobin gene, co-functioning of routine phosphate-binding and special bicarbonate-binding oxygen transport, and positively selected energy metabolism, ammonium bicarbonate excretion and cardiac muscle contraction. Further, we elucidated the robust Alligator sinensis sensory system, including a significantly expanded olfactory receptor repertoire, rapidly evolving nerve-related cellular components and visual perception, and positive selection of the night vision-related opsin and sound detection-associated otopetrin. We also discovered a well-developed immune system with a considerable number of lineage-specific antigen-presentation genes for adaptive immunity as well as expansion of the tripartite motif-containing C-type lectin and butyrophilin genes for innate immunity and expression of antibacterial peptides. Multifluorescence in situ hybridization showed that alligator chromosome 3, which encodes DMRT1, exhibits significant synteny with chicken chromosome Z. Finally, population history analysis indicated population admixture 0.60-1.05 million years ago, when the Qinghai-Tibetan Plateau was uplifted. PMID:23917531

Genome analysis and signature discovery for diving and sensory properties of the endangered Chinese alligator.

PubMed

Wan, Qiu-Hong; Pan, Sheng-Kai; Hu, Li; Zhu, Ying; Xu, Peng-Wei; Xia, Jin-Quan; Chen, Hui; He, Gen-Yun; He, Jing; Ni, Xiao-Wei; Hou, Hao-Long; Liao, Sheng-Guang; Yang, Hai-Qiong; Chen, Ying; Gao, Shu-Kun; Ge, Yun-Fa; Cao, Chang-Chang; Li, Peng-Fei; Fang, Li-Ming; Liao, Li; Zhang, Shu; Wang, Meng-Zhen; Dong, Wei; Fang, Sheng-Guo

2013-09-01

Crocodilians are diving reptiles that can hold their breath under water for long periods of time and are crepuscular animals with excellent sensory abilities. They comprise a sister lineage of birds and have no sex chromosome. Here we report the genome sequence of the endangered Chinese alligator (Alligator sinensis) and describe its unique features. The next-generation sequencing generated 314 Gb of raw sequence, yielding a genome size of 2.3 Gb. A total of 22 200 genes were predicted in Alligator sinensis using a de novo, homology- and RNA-based combined model. The genetic basis of long-diving behavior includes duplication of the bicarbonate-binding hemoglobin gene, co-functioning of routine phosphate-binding and special bicarbonate-binding oxygen transport, and positively selected energy metabolism, ammonium bicarbonate excretion and cardiac muscle contraction. Further, we elucidated the robust Alligator sinensis sensory system, including a significantly expanded olfactory receptor repertoire, rapidly evolving nerve-related cellular components and visual perception, and positive selection of the night vision-related opsin and sound detection-associated otopetrin. We also discovered a well-developed immune system with a considerable number of lineage-specific antigen-presentation genes for adaptive immunity as well as expansion of the tripartite motif-containing C-type lectin and butyrophilin genes for innate immunity and expression of antibacterial peptides. Multifluorescence in situ hybridization showed that alligator chromosome 3, which encodes DMRT1, exhibits significant synteny with chicken chromosome Z. Finally, population history analysis indicated population admixture 0.60-1.05 million years ago, when the Qinghai-Tibetan Plateau was uplifted.

Cardiac damage in athlete's heart: When the "supernormal" heart fails!

PubMed

Carbone, Andreina; D'Andrea, Antonello; Riegler, Lucia; Scarafile, Raffaella; Pezzullo, Enrica; Martone, Francesca; America, Raffaella; Liccardo, Biagio; Galderisi, Maurizio; Bossone, Eduardo; Calabrò, Raffaele

2017-06-26

Intense exercise may cause heart remodeling to compensate increases in blood pressure or volume by increasing muscle mass. Cardiac changes do not involve only the left ventricle, but all heart chambers. Physiological cardiac modeling in athletes is associated with normal or enhanced cardiac function, but recent studies have documented decrements in left ventricular function during intense exercise and the release of cardiac markers of necrosis in athlete's blood of uncertain significance. Furthermore, cardiac remodeling may predispose athletes to heart disease and result in electrical remodeling, responsible for arrhythmias. Athlete's heart is a physiological condition and does not require a specific treatment. In some conditions, it is important to differentiate the physiological adaptations from pathological conditions, such as hypertrophic cardiomyopathy, arrhythmogenic dysplasia of the right ventricle, and non-compaction myocardium, for the greater risk of sudden cardiac death of these conditions. Moreover, some drugs and performance-enhancing drugs can cause structural alterations and arrhythmias, therefore, their use should be excluded.

Cardiac damage in athlete’s heart: When the “supernormal” heart fails!

PubMed Central

Carbone, Andreina; D’Andrea, Antonello; Riegler, Lucia; Scarafile, Raffaella; Pezzullo, Enrica; Martone, Francesca; America, Raffaella; Liccardo, Biagio; Galderisi, Maurizio; Bossone, Eduardo; Calabrò, Raffaele

2017-01-01

Intense exercise may cause heart remodeling to compensate increases in blood pressure or volume by increasing muscle mass. Cardiac changes do not involve only the left ventricle, but all heart chambers. Physiological cardiac modeling in athletes is associated with normal or enhanced cardiac function, but recent studies have documented decrements in left ventricular function during intense exercise and the release of cardiac markers of necrosis in athlete’s blood of uncertain significance. Furthermore, cardiac remodeling may predispose athletes to heart disease and result in electrical remodeling, responsible for arrhythmias. Athlete’s heart is a physiological condition and does not require a specific treatment. In some conditions, it is important to differentiate the physiological adaptations from pathological conditions, such as hypertrophic cardiomyopathy, arrhythmogenic dysplasia of the right ventricle, and non-compaction myocardium, for the greater risk of sudden cardiac death of these conditions. Moreover, some drugs and performance-enhancing drugs can cause structural alterations and arrhythmias, therefore, their use should be excluded. PMID:28706583

[New aspects of the molecular effect of anti-arrhythmia agents].

PubMed

Honerjäger, P

1990-04-01

Excitation propagation is mediated by the brief opening of voltage-dependent Na-channels in the plasma membranes of cells of the conduction system and working myocardium. The refractory period is a function of the re-availability of the Na-channel for renewed opening. Most antiarrhythmic agents block cardiac Na-channels and, consequently, affect the desired refractory period prolongation. At the same time, however, dependent on the concentration and the substance, they slow conduction; an effect which can facilitate reentry excitation in the injured heart. The Na-channel blocking drugs, class I antiarrhythmic agents, are distinguished from the beta-receptor blockers, class II, repolarizing prolonging drugs, class III, and the cardiac Ca-channel blocking drugs (class IV) (Table 1). MOLECULAR STRUCTURE OF THE CARDIAC NA-CHANNEL: Voltage-dependent Na-channels which have been structurally elucidated to date are glycoprotein macromolecules of about 2000 amino acids with a molecular weight of about 260,000. Beginning at the amino terminal, four consecutive homologous domains can be differentiated which are composed of six transmembranous segments each. The terminal portion of the chain as well as the connecting segments between the domains appear intracellular. There are important relationships between the molecular structure and the function of the Na-channel (Figure 1). On comparison of the primary structures of neuronal and cardiac Na-channels, domains I to IV as well as the connecting segment between domains III and IV, are nearly identical. Homology in all of the remaining molecular regions, in contrast, is less than 70%. These segments as well as the differing structure of the four S5-S6 connecting chains may be responsible for the varying functional response of the cardiac Na-channels. MOLECULAR SITE OF ACTION OF ANTIARRHYTHMIC AGENTS AT THE CARDIAC NA-CHANNEL: Since most antiarrhythmic agents are weak bases with pK values between 7.5 and 9.5, in the physiologic range of pH, they are present in part in the protonated, positively-charged form, in part as uncharged free base. It is assumed that the Na-channel of nerve and skeletal muscle has one receptor for local anesthetics at which both the protonated and the uncharged molecular forms bind. The receptor is thought to be located on the inner wall of the ion pore about half of the distance between the intracellular and the extracellular channel opening. The uncharged form of the Na-channel blocker penetrates directly from the lipid phase of the surrounding cell membrane, the protonated form only from the intracellular space during the short opening of the channel at the beginning of the action potential. Through binding on the receptor, the Na-channel is blocked. Dissociation of the molecular forms takes place in the same manner. The peptide region on which antiarrhythmic drugs bind, however, has not been identified. By means of the patch-clamp technique, it has been shown that on extracellular application of the quaternary lidocaine derivative QX-314 there is a rapid and marked reduction of Na-flux in cardiac Purkinje fibers in contrast to the effects at neuronal and skeletal muscle Na-channels. Intracellular application similarly leads to blockade but only in the course of repetitive depolarizations indicating that the cardiac Na-channel may have a second binding site for local anesthetics at the extracellular side.(ABSTRACT TRUNCATED AT 400 WORDS)

Post-operative ventricular flow dynamics following atrioventricular valve surgical and device therapies: A review.

PubMed

Nguyen, Yen Ngoc; Ismail, Munirah; Kabinejadian, Foad; Tay, Edgar Lik Wui; Leo, Hwa Liang

2018-04-01

Intra-ventricular flow dynamics has recently emerged as an important evaluation and diagnosis tool in different cardiovascular conditions. The formation of vortex pattern during the cardiac cycle has been suggested to play important epigenetic and energy-modulation roles in cardiac remodelling, adaptations and mal-adaptations. In this new perspective, flow alterations due to different cardiovascular procedures can affect the long-term outcome of those procedures. Especially, repairs and replacements performed on atrioventricular valves are likely to exert direct impact on intra-ventricular flow pattern. In this review, current consensus around the roles of vortex dynamics in cardiac function is discussed. An overview of physiological vortex patterns found in healthy left and right ventricles as well as post-operative ventricular flow phenomenon owing to different atrioventricular valvular procedures are reviewed, followed by the summary of different vortex identification schemes used to characterise intraventricular flow. This paper also emphasises on future research directions towards a comprehensive understanding of intra-cardiac flow and its clinical relevance. The knowledge could encourage more effective pre-operative planning and better outcomes for current clinical practices. Copyright © 2018. Published by Elsevier Ltd.

Binding of KATP channel modulators in rat cardiac membranes

PubMed Central

Löffler-Walz, Cornelia; Quast, Ulrich

1998-01-01

The binding of [3H]-P1075, a potent opener of adenosine-5′-triphosphate-(ATP)-sensitive K+ channels, was studied in a crude heart membrane preparation of the rat, at 37°C.Binding required MgATP. In the presence of an ATP-regenerating system, MgATP supported [3H]-P1075 binding with an EC50 value of 100 μM and a Hill coefficient of 1.4.In saturation experiments [3H]-P1075 binding was homogeneous with a KD value of 6±1 nM and a binding capacity (Bmax) of 33±3 fmol mg−1 protein.Upon addition of an excess of unlabelled P1075, the [3H]-P1075-receptor complex dissociated in a mono-exponential manner with a dissociation rate constant of 0.13±0.01 min−1. If a bi-molecular association mechanism was assumed, the dependence of the association kinetics on label concentration gave an association rate constant of 0.030±0.003 nM−1 min−1. From the kinetic experiments the KD value was calculated as 4.7±0.6 nM.Openers of the ATP-sensitive K+ channel belonging to different structural classes inhibited specific [3H]-P1075 binding in a monophasic manner to completion; an exception was minoxidil sulphate where maximum inhibition was 68%. The potencies of the openers in this assay agree with published values obtained in rat cardiocytes and are on average 3.5 times lower than those determined in rat aorta.Sulphonylureas, such as glibenclamide and glibornuride and the sulphonylurea-related carboxylate, AZ-DF 265, inhibited [3H]-P1075 binding with biphasic inhibition curves. The high affinity component comprised about 60% of the curves with the IC50 value of glibenclamide being ≈amp;90 nM; affinities for the low affinity component were in the μM concentration range. The fluorescein derivative, phloxine B, showed a monophasic inhibition curve with an IC50 value of 6 μM, a maximum inhibition of 94% and a Hill coefficient of 1.5.It is concluded that binding studies with [3H]-P1075 are feasible in rat heart membranes in the presence of MgATP and of an ATP-regenerating system. The pharmacological profile of the [3H]-P1075 binding sites in the cardiac preparation, which probably contains sulphonylurea receptors (SURs) from cardiac myocytes (SUR2A) and vascular smooth muscle cells (SUR2B), differs from that expected for SUR2A and SUR2B. PMID:9579735

Long-Term Adaptive Servo-Ventilator Treatment Prevents Cardiac Death and Improves Clinical Outcome.

PubMed

Imamura, Teruhiko; Kinugawa, Koichiro; Nitta, Daisuke; Komuro, Issei

2016-01-01

Adaptive servo-ventilation (ASV) is a recently developed, noninvasive therapeutic tool for the treatment of heart failure (HF). However, the efficacy of ASV therapy in patients with advanced HF remains uncertain, especially as regards its contribution to freedom from cardiac replacement therapy. A total of 85 patients with advanced HF (New York Heart Association [NYHA] class IV 71%, inotrope infusion-dependent 34%) refractory to guideline-directed medical therapy, received ASV therapy, irrespective of sleep-disordered breathing, at our institute between 2008 and 2014. Among these 85 patients, 46 continued ASV therapy for > 1 month (continued group), whereas 39 discontinued the therapy after < 1 month because of intolerance (discontinued group). There were no significant differences in baseline variables between the two groups. Heart rate indicating sympathetic activity, left ventricular (LV) reverse remodeling assessed by LV diastolic diameter, LV ejection fraction, and the grades of mitral and tricuspid regurgitations, HF severity assessed by NYHA class and plasma level of B-type natriuretic peptide, and end-organ dysfunction, improved significantly at 6 months following the initiation of ASV therapy (P < 0.05 for all). All-cause mortality and cardiac death rate were significantly lower during 2-year follow up in the continued group (P < 0.05 for both). In conclusion, ASV is a novel therapeutic tool prior to cardiac replacement therapy in patients with advanced HF and may prolong the period until cardiac replacement therapy becomes necessary.

Differential Lectin Binding Patterns Identify Distinct Heart Regions in Giant Danio (Devario aequipinnatus) and Zebrafish (Danio rerio) Hearts

PubMed Central

Manalo, Trina; May, Adam; Quinn, Joshua; Lafontant, Dominique S.; Shifatu, Olubusola; He, Wei; Gonzalez-Rosa, Juan M.; Burns, Geoffrey C.; Burns, Caroline E.; Burns, Alan R.; Lafontant, Pascal J.

2016-01-01

Lectins are carbohydrate-binding proteins commonly used as biochemical and histochemical tools to study glycoconjugate (glycoproteins, glycolipids) expression patterns in cells, tissues, including mammalian hearts. However, lectins have received little attention in zebrafish (Danio rerio) and giant danio (Devario aequipinnatus) heart studies. Here, we sought to determine the binding patterns of six commonly used lectins—wheat germ agglutinin (WGA), Ulex europaeus agglutinin, Bandeiraea simplicifolia lectin (BS lectin), concanavalin A (Con A), Ricinus communis agglutinin I (RCA I), and Lycopersicon esculentum agglutinin (tomato lectin)—in these hearts. Con A showed broad staining in the myocardium. WGA stained cardiac myocyte borders, with binding markedly stronger in the compact heart and bulbus. BS lectin, which stained giant danio coronaries, was used to measure vascular reconstruction during regeneration. However, BS lectin reacted poorly in zebrafish. RCA I stained the compact heart of both fish. Tomato lectin stained the giant danio, and while low reactivity was seen in the zebrafish ventricle, staining was observed in their transitional cardiac myocytes. In addition, we observed unique staining patterns in the developing zebrafish heart. Lectins’ ability to reveal differential glycoconjugate expression in giant danio and zebrafish hearts suggests they can serve as simple but important tools in studies of developing, adult, and regenerating fish hearts. PMID:27680670

Effects of hypertrophic and dilated cardiomyopathy mutations on power output by human β-cardiac myosin.

PubMed

Spudich, James A; Aksel, Tural; Bartholomew, Sadie R; Nag, Suman; Kawana, Masataka; Yu, Elizabeth Choe; Sarkar, Saswata S; Sung, Jongmin; Sommese, Ruth F; Sutton, Shirley; Cho, Carol; Adhikari, Arjun S; Taylor, Rebecca; Liu, Chao; Trivedi, Darshan; Ruppel, Kathleen M

2016-01-01

Hypertrophic cardiomyopathy is the most frequently occurring inherited cardiovascular disease, with a prevalence of more than one in 500 individuals worldwide. Genetically acquired dilated cardiomyopathy is a related disease that is less prevalent. Both are caused by mutations in the genes encoding the fundamental force-generating protein machinery of the cardiac muscle sarcomere, including human β-cardiac myosin, the motor protein that powers ventricular contraction. Despite numerous studies, most performed with non-human or non-cardiac myosin, there is no clear consensus about the mechanism of action of these mutations on the function of human β-cardiac myosin. We are using a recombinantly expressed human β-cardiac myosin motor domain along with conventional and new methodologies to characterize the forces and velocities of the mutant myosins compared with wild type. Our studies are extending beyond myosin interactions with pure actin filaments to include the interaction of myosin with regulated actin filaments containing tropomyosin and troponin, the roles of regulatory light chain phosphorylation on the functions of the system, and the possible roles of myosin binding protein-C and titin, important regulatory components of both cardiac and skeletal muscles. © 2016. Published by The Company of Biologists Ltd.

ATP interacts with the CPVT mutation-associated central domain of the cardiac ryanodine receptor.

PubMed

Blayney, Lynda; Beck, Konrad; MacDonald, Ewan; D'Cruz, Leon; Nomikos, Michail; Griffiths, Julia; Thanassoulas, Angelos; Nounesis, George; Lai, F Anthony

2013-10-01

This study was designed to determine whether the cardiac ryanodine receptor (RyR2) central domain, a region associated with catecholamine polymorphic ventricular tachycardia (CPVT) mutations, interacts with the RyR2 regulators, ATP and the FK506-binding protein 12.6 (FKBP12.6). Wild-type (WT) RyR2 central domain constructs (G(2236)to G(2491)) and those containing the CPVT mutations P2328S and N2386I, were expressed as recombinant proteins. Folding and stability of the proteins were examined by circular dichroism (CD) spectroscopy and guanidine hydrochloride chemical denaturation. The far-UV CD spectra showed a soluble stably-folded protein with WT and mutant proteins exhibiting a similar secondary structure. Chemical denaturation analysis also confirmed a stable protein for both WT and mutant constructs with similar two-state unfolding. ATP and caffeine binding was measured by fluorescence spectroscopy. Both ATP and caffeine bound with an EC50 of ~200-400μM, and the affinity was the same for WT and mutant constructs. Sequence alignment with other ATP binding proteins indicated the RyR2 central domain contains the signature of an ATP binding pocket. Interaction of the central domain with FKBP12.6 was tested by glutaraldehyde cross-linking and no association was found. The RyR2 central domain, expressed as a 'correctly' folded recombinant protein, bound ATP in accord with bioinformatics evidence of conserved ATP binding sequence motifs. An interaction with FKBP12.6 was not evident. CPVT mutations did not disrupt the secondary structure nor binding to ATP. Part of the RyR2 central domain CPVT mutation cluster, can be expressed independently with retention of ATP binding. Copyright © 2013 Elsevier B.V. All rights reserved.

A double tyrosine motif in the cardiac sodium channel domain III-IV linker couples calcium-dependent calmodulin binding to inactivation gating.

PubMed

Sarhan, Maen F; Van Petegem, Filip; Ahern, Christopher A

2009-11-27

Voltage-gated sodium channels maintain the electrical cadence and stability of neurons and muscle cells by selectively controlling the transmembrane passage of their namesake ion. The degree to which these channels contribute to cellular excitability can be managed therapeutically or fine-tuned by endogenous ligands. Intracellular calcium, for instance, modulates sodium channel inactivation, the process by which sodium conductance is negatively regulated. We explored the molecular basis for this effect by investigating the interaction between the ubiquitous calcium binding protein calmodulin (CaM) and the putative sodium channel inactivation gate composed of the cytosolic linker between homologous channel domains III and IV (DIII-IV). Experiments using isothermal titration calorimetry show that CaM binds to a novel double tyrosine motif in the center of the DIII-IV linker in a calcium-dependent manner, N-terminal to a region previously reported to be a CaM binding site. An alanine scan of aromatic residues in recombinant DIII-DIV linker peptides shows that whereas multiple side chains contribute to CaM binding, two tyrosines (Tyr(1494) and Tyr(1495)) play a crucial role in binding the CaM C-lobe. The functional relevance of these observations was then ascertained through electrophysiological measurement of sodium channel inactivation gating in the presence and absence of calcium. Experiments on patch-clamped transfected tsA201 cells show that only the Y1494A mutation of the five sites tested renders sodium channel steady-state inactivation insensitive to cytosolic calcium. The results demonstrate that calcium-dependent calmodulin binding to the sodium channel inactivation gate double tyrosine motif is required for calcium regulation of the cardiac sodium channel.

[Application of IMA and H-FABP in Forensic Diagnosis of Sudden Cardiac Death].

PubMed

Zhu, Z L; Wang, P; You, J B; Yue, Q; Wang, P F; Wang, X L; Zhang, C N; Zhang, G H

2017-08-01

Acute myocardial ischemia is the most common cause of sudden cardiac death. The diagnosis of early myocardial ischemia is a hot point in forensic medicine, which is also an early and important part for a prevention against myocardial infarction. This paper conducts a comprehensive discussion of the structure, function, clinical value and forensic medicine application prospect of ischemia modified albumin （IMA） and heart-type fatty acid binding protein （H-FABP), aiming to determine whether the two proteins can be used as biochemical detection indicators of early myocardial ischemia for the diagnosis of sudden cardiac death in forensic medicine. Copyright© by the Editorial Department of Journal of Forensic Medicine.

Transient Receptor Potential Vanilloid 2 Regulates Myocardial Response to Exercise

PubMed Central

Naticchioni, Mindi; Karani, Rajiv; Smith, Margaret A.; Onusko, Evan; Robbins, Nathan; Jiang, Min; Radzyukevich, Tatiana; Fulford, Logan; Gao, Xu; Apel, Ryan; Heiny, Judith; Rubinstein, Jack; Koch, Sheryl E.

2015-01-01

The myocardial response to exercise is an adaptive mechanism that permits the heart to maintain cardiac output via improved cardiac function and development of hypertrophy. There are many overlapping mechanisms via which this occurs with calcium handling being a crucial component of this process. Our laboratory has previously found that the stretch sensitive TRPV2 channels are active regulators of calcium handling and cardiac function under baseline conditions based on our observations that TRPV2-KO mice have impaired cardiac function at baseline. The focus of this study was to determine the cardiac function of TRPV2-KO mice under exercise conditions. We measured skeletal muscle at baseline in WT and TRPV2-KO mice and subjected them to various exercise protocols and measured the cardiac response using echocardiography and molecular markers. Our results demonstrate that the TRPV2-KO mouse did not tolerate forced exercise although they became increasingly exercise tolerant with voluntary exercise. This occurs as the cardiac function deteriorates further with exercise. Thus, our conclusion is that TRPV2-KO mice have impaired cardiac functional response to exercise. PMID:26356305

Snf1-related kinase improves cardiac mitochondrial efficiency and decreases mitochondrial uncoupling

PubMed Central

Rines, Amy K.; Chang, Hsiang-Chun; Wu, Rongxue; Sato, Tatsuya; Khechaduri, Arineh; Kouzu, Hidemichi; Shapiro, Jason; Shang, Meng; Burke, Michael A.; Abdelwahid, Eltyeb; Jiang, Xinghang; Chen, Chunlei; Rawlings, Tenley A.; Lopaschuk, Gary D.; Schumacker, Paul T.; Abel, E. Dale; Ardehali, Hossein

2017-01-01

Ischaemic heart disease limits oxygen and metabolic substrate availability to the heart, resulting in tissue death. Here, we demonstrate that the AMP-activated protein kinase (AMPK)-related protein Snf1-related kinase (SNRK) decreases cardiac metabolic substrate usage and mitochondrial uncoupling, and protects against ischaemia/reperfusion. Hearts from transgenic mice overexpressing SNRK have decreased glucose and palmitate metabolism and oxygen consumption, but maintained power and function. They also exhibit decreased uncoupling protein 3 (UCP3) and mitochondrial uncoupling. Conversely, Snrk knockout mouse hearts have increased glucose and palmitate oxidation and UCP3. SNRK knockdown in cardiac cells decreases mitochondrial efficiency, which is abolished with UCP3 knockdown. We show that Tribbles homologue 3 (Trib3) binds to SNRK, and downregulates UCP3 through PPARα. Finally, SNRK is increased in cardiomyopathy patients, and SNRK reduces infarct size after ischaemia/reperfusion. SNRK also decreases cardiac cell death in a UCP3-dependent manner. Our results suggest that SNRK improves cardiac mitochondrial efficiency and ischaemic protection. PMID:28117339

How to Practice Sports Cardiology: A Cardiology Perspective.

PubMed

Lawless, Christine E

2015-07-01

The rigorous cardiovascular (CV) demands of sport, combined with training-related cardiac adaptations, render the athlete a truly unique CV patient and sports cardiology a truly unique discipline. Cardiologists are advised to adopt a systematic approach to the CV evaluation of athletes, taking into consideration the individual sports culture, sports-specific CV demands, CV adaptations and their appearance on cardiac testing, any existing or potential interaction of the heart with the internal and external sports environment, short- and long-term CV risks, and potential effect of performance-enhancing agents and antidoping regulations. This article outlines the systematic approach, provides a detailed example, and outlines contemporary sports cardiology core competencies. Copyright © 2015 Elsevier Inc. All rights reserved.

Risk of Cardiac Rhythm Problems During Spaceflight

NASA Technical Reports Server (NTRS)

Lee, Stuart M. C.; Stenger, Michael B.; Laurie, Steven S.; Macias, Brandon R.

2017-01-01

NASA has concerns regarding the incidence and clinical significance of cardiac arrhythmias that could occur during long-term exposure to the spaceflight environment, such as on the International Space Station (ISS) or during a prolonged (e.g., up to 3 years) sojourn to Mars or on the Moon. There have been some anecdotal reports and a few documented cases of cardiac arrhythmias in space, including one documented episode of non-sustained ventricular tachycardia. The potential catastrophic nature of a sudden cardiac death in the remote space environment has led to concerns from the early days of the space program that spaceflight might be arrhythmogenic. Indeed, there are known and well-defined changes in the cardiovascular system with spaceflight: a) plasma volume is reduced, b) left ventricular mass is decreased, and c) the autonomic nervous system adapts to the weightless environment. Combined, these physiologic adaptations suggest that changes in cardiac structure and neuro-humoral environment during spaceflight could alter electrical conduction, although the evidence supporting this contention consists mostly of minor changes in QT interval (the time between the start of the Q wave and the end of the T wave on an electrocardiogram tracing) in a small number of astronauts after long-duration spaceflight. Concurrent with efforts by NASA Medical Operations to refine and improve screening techniques relevant to arrhythmias and cardiovascular disease, as NASA enters the era of exploration-class missions it will be critical to determine with the highest degree of certainty whether spaceflight by itself alters cardiac structure and function sufficiently to increase the risk of arrhythmias.

Modeling hypertrophic IP3 transients in the cardiac myocyte.

PubMed

Cooling, Michael; Hunter, Peter; Crampin, Edmund J

2007-11-15

Cardiac hypertrophy is a known risk factor for heart disease, and at the cellular level is caused by a complex interaction of signal transduction pathways. The IP3-calcineurin pathway plays an important role in stimulating the transcription factor NFAT which binds to DNA cooperatively with other hypertrophic transcription factors. Using available kinetic data, we construct a mathematical model of the IP3 signal production system after stimulation by a hypertrophic alpha-adrenergic agonist (endothelin-1) in the mouse atrial cardiac myocyte. We use a global sensitivity analysis to identify key controlling parameters with respect to the resultant IP3 transient, including the phosphorylation of cell-membrane receptors, the ligand strength and binding kinetics to precoupled (with G(alpha)GDP) receptor, and the kinetics associated with precoupling the receptors. We show that the kinetics associated with the receptor system contribute to the behavior of the system to a great extent, with precoupled receptors driving the response to extracellular ligand. Finally, by reparameterizing for a second hypertrophic alpha-adrenergic agonist, angiotensin-II, we show that differences in key receptor kinetic and membrane density parameters are sufficient to explain different observed IP3 transients in essentially the same pathway.

skNAC, a Smyd1-interacting transcription factor, is involved in cardiac development and skeletal muscle growth and regeneration.

PubMed

Park, Chong Yon; Pierce, Stephanie A; von Drehle, Morgan; Ivey, Kathryn N; Morgan, Jayson A; Blau, Helen M; Srivastava, Deepak

2010-11-30

Cardiac and skeletal muscle development and maintenance require complex interactions between DNA-binding proteins and chromatin remodeling factors. We previously reported that Smyd1, a muscle-restricted histone methyltransferase, is essential for cardiogenesis and functions with a network of cardiac regulatory proteins. Here we show that the muscle-specific transcription factor skNAC is the major binding partner for Smyd1 in the developing heart. Targeted deletion of skNAC in mice resulted in partial embryonic lethality by embryonic day 12.5, with ventricular hypoplasia and decreased cardiomyocyte proliferation that were similar but less severe than in Smyd1 mutants. Expression of Irx4, a ventricle-specific transcription factor down-regulated in hearts lacking Smyd1, also depended on the presence of skNAC. Viable skNAC(-/-) adult mice had reduced postnatal skeletal muscle growth and impaired regenerative capacity after cardiotoxin-induced injury. Satellite cells isolated from skNAC(-/-) mice had impaired survival compared with wild-type littermate satellite cells. Our results indicate that skNAC plays a critical role in ventricular cardiomyocyte expansion and regulates postnatal skeletal muscle growth and regeneration in mice.

Cardiac vagal control and children’s adaptive functioning: A meta-analysis

PubMed Central

Graziano, Paulo; Derefinko, Karen

2014-01-01

Polyvagal theory has influenced research on the role of cardiac vagal control, indexed by respiratory sinus arrhythmia withdrawal (RSA-W) during challenging states, in children’s self-regulation. However, it remains unclear how well RSA-W predicts adaptive functioning (AF) outcomes and whether certain caveats of measuring RSA (e.g., respiration) significantly impact these associations. A meta-analysis of 44 studies (n = 4,996 children) revealed small effect sizes such that greater levels of RSA-W were related to fewer externalizing, internalizing, and cognitive/academic problems. In contrast, RSA-W was differentially related to children’s social problems according to sample type (community vs. clinical/at-risk). The relations between RSA-W and children’s AF outcomes were stronger among studies that co-varied baseline RSA and in Caucasian children (no effect was found for respiration). Children from clinical/at-risk samples displayed lower levels of baseline RSA and RSA-W compared to children from community samples. Theoretical/practical implications for the study of cardiac vagal control are discussed. PMID:23648264

Syndecans in heart fibrosis.

PubMed

Lunde, Ida G; Herum, Kate M; Carlson, Cathrine C; Christensen, Geir

2016-09-01

Heart disease is a deadly syndrome affecting millions worldwide. It reflects an unmet clinical need, and the disease mechanisms are poorly understood. Cardiac fibrosis is central to heart disease. The four-membered family of transmembrane proteoglycans, syndecan-1 to -4, is believed to regulate fibrosis. We review the current literature concerning syndecans in cardiac fibrosis. Syndecan expression is up-regulated in response to pro-inflammatory stimuli in various forms of heart disease with fibrosis. Mice lacking syndecan-1 and -4 show reduced activation of pro-fibrotic signaling and increased cardiac rupture upon infarction indicating an important role for these molecules. Whereas the short cytoplasmic tail of syndecans regulates signaling, their extracellular part, substituted with heparan sulfate glycosaminoglycan chains, binds a plethora of extracellular matrix (ECM) molecules involved in fibrosis, e.g., collagens, growth factors, cytokines, and immune cell adhesion proteins. Full-length syndecans induce pro-fibrotic signaling, increasing the expression of collagens, myofibroblast differentiation factors, ECM enzymes, growth factors, and immune cell adhesion molecules, thereby also increasing cardiac stiffness and preventing cardiac rupture. Upon pro-inflammatory stimuli, syndecan ectodomains are enzymatically released from heart cells (syndecan shedding). Shed ectodomains affect the expression of ECM molecules, promoting ECM degradation and cardiac rupture upon myocardial infarction. Blood levels of shed syndecan-1 and -4 ectodomains are associated with hospitalization, mortality, and heart remodeling in patients with heart failure. Improved understanding of syndecans and their modifying enzymes in cardiac fibrosis might contribute to the development of compounds with therapeutic potential, and enzymatically shed syndecan ectodomains might constitute a future prognostic tool for heart diseases with fibrosis. Graphical Abstract Graphical abstract summarizing the contents of the current review on syndecans in cardiac fibrosis. The heart is subjected to various forms of pathological stimuli, e.g., myocardial infarction, hypertension, valvular stenosis, infection, or an inherited genetic mutation, triggering responses in cells resident in the heart. Here, we focus on the responses of cardiac fibroblasts directing changes in the extracellular matrix resulting in cardiac fibrosis. A family of four transmembrane proteoglycans, syndecan-1 to -4, is expressed in the cell membrane of cardiac fibroblasts and is generally up-regulated in response to the above-mentioned pathological stimuli. Syndecans carry glycosaminoglycan chains on their extracellular domain, binding a plethora of molecules involved in fibrosis, e.g., growth factors, cytokines, immune cell adhesion proteins, and pathogens. Syndecans have a short cytoplasmic tail involved in pro-fibrotic signaling. The signaling and cellular processes governed by syndecans in the heart in response to pathological stimuli regulate important aspects of extracellular matrix remodeling and fibrosis and have mainly been studied in cardiac remodeling in response to cardiac infarction and pressure overload. In general, adequate timing and the quantity and quality of fibrosis are absolutely crucial for heart function and survival, determining cardiac stiffness, contractility, compliance, probability of rupture, dilation, and diastolic and systolic function. Syndecan-1 and -4 have mainly been studied in the heart and are discussed in this review (LV left ventricle).

Evolution of RNA-Protein Interactions: Non-Specific Binding Led to RNA Splicing Activity of Fungal Mitochondrial Tyrosyl-tRNA Synthetases

PubMed Central

Lamech, Lilian T.; Mallam, Anna L.; Lambowitz, Alan M.

2014-01-01

The Neurospora crassa mitochondrial tyrosyl-tRNA synthetase (mtTyrRS; CYT-18 protein) evolved a new function as a group I intron splicing factor by acquiring the ability to bind group I intron RNAs and stabilize their catalytically active RNA structure. Previous studies showed: (i) CYT-18 binds group I introns by using both its N-terminal catalytic domain and flexibly attached C-terminal anticodon-binding domain (CTD); and (ii) the catalytic domain binds group I introns specifically via multiple structural adaptations that occurred during or after the divergence of Peziomycotina and Saccharomycotina. However, the function of the CTD and how it contributed to the evolution of splicing activity have been unclear. Here, small angle X-ray scattering analysis of CYT-18 shows that both CTDs of the homodimeric protein extend outward from the catalytic domain, but move inward to bind opposite ends of a group I intron RNA. Biochemical assays show that the isolated CTD of CYT-18 binds RNAs non-specifically, possibly contributing to its interaction with the structurally different ends of the intron RNA. Finally, we find that the yeast mtTyrRS, which diverged from Pezizomycotina fungal mtTyrRSs prior to the evolution of splicing activity, binds group I intron and other RNAs non-specifically via its CTD, but lacks further adaptations needed for group I intron splicing. Our results suggest a scenario of constructive neutral (i.e., pre-adaptive) evolution in which an initial non-specific interaction between the CTD of an ancestral fungal mtTyrRS and a self-splicing group I intron was “fixed” by an intron RNA mutation that resulted in protein-dependent splicing. Once fixed, this interaction could be elaborated by further adaptive mutations in both the catalytic domain and CTD that enabled specific binding of group I introns. Our results highlight a role for non-specific RNA binding in the evolution of RNA-binding proteins. PMID:25536042

Evolution of RNA-protein interactions: non-specific binding led to RNA splicing activity of fungal mitochondrial tyrosyl-tRNA synthetases.

PubMed

Lamech, Lilian T; Mallam, Anna L; Lambowitz, Alan M

2014-12-01

The Neurospora crassa mitochondrial tyrosyl-tRNA synthetase (mtTyrRS; CYT-18 protein) evolved a new function as a group I intron splicing factor by acquiring the ability to bind group I intron RNAs and stabilize their catalytically active RNA structure. Previous studies showed: (i) CYT-18 binds group I introns by using both its N-terminal catalytic domain and flexibly attached C-terminal anticodon-binding domain (CTD); and (ii) the catalytic domain binds group I introns specifically via multiple structural adaptations that occurred during or after the divergence of Peziomycotina and Saccharomycotina. However, the function of the CTD and how it contributed to the evolution of splicing activity have been unclear. Here, small angle X-ray scattering analysis of CYT-18 shows that both CTDs of the homodimeric protein extend outward from the catalytic domain, but move inward to bind opposite ends of a group I intron RNA. Biochemical assays show that the isolated CTD of CYT-18 binds RNAs non-specifically, possibly contributing to its interaction with the structurally different ends of the intron RNA. Finally, we find that the yeast mtTyrRS, which diverged from Pezizomycotina fungal mtTyrRSs prior to the evolution of splicing activity, binds group I intron and other RNAs non-specifically via its CTD, but lacks further adaptations needed for group I intron splicing. Our results suggest a scenario of constructive neutral (i.e., pre-adaptive) evolution in which an initial non-specific interaction between the CTD of an ancestral fungal mtTyrRS and a self-splicing group I intron was "fixed" by an intron RNA mutation that resulted in protein-dependent splicing. Once fixed, this interaction could be elaborated by further adaptive mutations in both the catalytic domain and CTD that enabled specific binding of group I introns. Our results highlight a role for non-specific RNA binding in the evolution of RNA-binding proteins.

Transcriptional activation of the Escherichia coli adaptive response gene aidB is mediated by binding of methylated Ada protein. Evidence for a new consensus sequence for Ada-binding sites.

PubMed

Landini, P; Volkert, M R

1995-04-07

The Escherichia coli aidB gene is part of the adaptive response to DNA methylation damage. Genes belonging to the adaptive response are positively regulated by the ada gene; the Ada protein acts as a transcriptional activator when methylated in one of its cysteine residues at position 69. Through DNaseI protection assays, we show that methylated Ada (meAda) is able to bind a DNA sequence between 40 and 60 base pairs upstream of the aidB transcriptional startpoint. Binding of meAda is necessary to activate transcription of the adaptive response genes; accordingly, in vitro transcription of aidB is dependent on the presence of meAda. Unmethylated Ada protein shows no protection against DNaseI digestion in the aidB promoter region nor does it promote aidB in vitro transcription. The aidB Ada-binding site shows only weak homology to the proposed consensus sequences for Ada-binding sites in E. coli (AAANNAA and AAAGCGCA) but shares a higher degree of similarity with the Ada-binding regions from other bacterial species, such as Salmonella typhimurium and Bacillus subtilis. Based on the comparison of five different Ada-dependent promoter regions, we suggest that a possible recognition sequence for meAda might be AATnnnnnnG-CAA. Higher concentrations of Ada are required for the binding of aidB than for the ada promoter, suggesting lower affinity of the protein for the aidB Ada-binding site. Common features in the Ada-binding regions of ada and aidB are a high A/T content, the presence of an inverted repeat structure, and their position relative to the transcriptional start site. We propose that these elements, in addition to the proposed recognition sequence, are important for binding of the Ada protein.

A landscape of circular RNA expression in the human heart.

PubMed

Tan, Wilson L W; Lim, Benson T S; Anene-Nzelu, Chukwuemeka G O; Ackers-Johnson, Matthew; Dashi, Albert; See, Kelvin; Tiang, Zenia; Lee, Dominic Paul; Chua, Wee Woon; Luu, Tuan D A; Li, Peter Y Q; Richards, Arthur Mark; Foo, Roger S Y

2017-03-01

Circular RNA (circRNA) is a newly validated class of single-stranded RNA, ubiquitously expressed in mammalian tissues and possessing key functions including acting as microRNA sponges and as transcriptional regulators by binding to RNA-binding proteins. While independent studies confirm the expression of circRNA in various tissue types, genome-wide circRNA expression in the heart has yet to be described in detail. We performed deep RNA-sequencing on ribosomal-depleted RNA isolated from 12 human hearts, 25 mouse hearts and across a 28-day differentiation time-course of human embryonic stem cell-derived cardiomyocytes. Using purpose-designed bioinformatics tools, we uncovered a total of 15 318 and 3017 cardiac circRNA within human and mouse, respectively. Their abundance generally correlates with the abundance of their cognate linear RNA, but selected circRNAs exist at disproportionately higher abundance. Top highly expressed circRNA corresponded to key cardiac genes including Titin (TTN), RYR2, and DMD. The most abundant cardiac-expressed circRNA is a cytoplasmic localized single-exon circSLC8A1-1. The longest human transcript TTN alone generates up to 415 different exonic circRNA isoforms, the majority (83%) of which originates from the I-band domain. Finally, we confirmed the expression of selected cardiac circRNA by RT-PCR, Sanger sequencing and single molecule RNA-fluorescence in situ hybridization. Our data provide a detailed circRNA expression landscape in hearts. There is a high-abundance of specific cardiac-expressed circRNA. These findings open up a new avenue for future investigation into this emerging class of RNA. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For Permissions, please email: journals.permissions@oup.com.

Novel Calmodulin (CALM2) Mutations Associated with Congenital Arrhythmia Susceptibility

PubMed Central

Makita, Naomasa; Yagihara, Nobue; Crotti, Lia; Johnson, Christopher N.; Beckmann, Britt-Maria; Roh, Michelle S.; Shigemizu, Daichi; Lichtner, Peter; Ishikawa, Taisuke; Aiba, Takeshi; Homfray, Tessa; Behr, Elijah R.; Klug, Didier; Denjoy, Isabelle; Mastantuono, Elisa; Theisen, Daniel; Tsunoda, Tatsuhiko; Satake, Wataru; Toda, Tatsushi; Nakagawa, Hidewaki; Tsuji, Yukiomi; Tsuchiya, Takeshi; Yamamoto, Hirokazu; Miyamoto, Yoshihiro; Endo, Naoto; Kimura, Akinori; Ozaki, Kouichi; Motomura, Hideki; Suda, Kenji; Tanaka, Toshihiro; Schwartz, Peter J.; Meitinger, Thomas; Kääb, Stefan; Guicheney, Pascale; Shimizu, Wataru; Bhuiyan, Zahurul A.; Watanabe, Hiroshi; Chazin, Walter J.; George, Alfred L.

2014-01-01

Background Genetic predisposition to life-threatening cardiac arrhythmias such as in congenital long-QT syndrome (LQTS) and catecholaminergic polymorphic ventricular tachycardia (CPVT) represent treatable causes of sudden cardiac death in young adults and children. Recently, mutations in calmodulin (CALM1, CALM2) have been associated with severe forms of LQTS and CPVT, with life-threatening arrhythmias occurring very early in life. Additional mutation-positive cases are needed to discern genotype-phenotype correlations associated with calmodulin mutations. Methods and Results We employed conventional and next-generation sequencing approaches including exome analysis in genotype-negative LQTS probands. We identified five novel de novo missense mutations in CALM2 in three subjects with LQTS (p.N98S, p.N98I, p.D134H) and two subjects with clinical features of both LQTS and CPVT (p.D132E, p.Q136P). Age of onset of major symptoms (syncope or cardiac arrest) ranged from 1–9 years. Three of five probands had cardiac arrest and one of these subjects did not survive. Although all probands had LQTS, two subjects also exhibited electrocardiographic features consistent with CPVT. The clinical severity among subjects in this series was generally less than that originally reported for CALM1 and CALM2 associated with recurrent cardiac arrest during infancy. Four of five probands responded to β-blocker therapy whereas one subject with mutation p.Q136P died suddenly during exertion despite this treatment. Mutations affect conserved residues located within calcium binding loops III (p.N98S, p.N98I) or IV (p.D132E, p.D134H, p.Q136P) and caused reduced calcium binding affinity. Conclusions CALM2 mutations can be associated with LQTS and with overlapping features of LQTS and CPVT. PMID:24917665

KLF5/BTEB2, a Krüppel-like zinc-finger type transcription factor, mediates both smooth muscle cell activation and cardiac hypertrophy.

PubMed

Nagai, Ryozo; Shindo, Takayuki; Manabe, Ichiro; Suzuki, Toru; Kurabayashi, Masahiko

2003-01-01

Cardiac and vascular biology need to be approached interactively because they share many common biological features as seen in activation of the local renin-angiotensin system, angiogenesis, and extracellular matrix production. We previously reported KLF5/BTEB2, a Krüppel-like zinc-finger type transcription factor, to activate various gene promoters that are activated in phenotypically modulated smooth muscle cells, such as a nonmuscle type myosin heavy chain gene SMemb, plasminogen activator inhibitor-1 (PAI-1), iNOS, PDGF-A, Egr-1 and VEGF receptors at least in vitro. KLF5/BTEB2 mRNA levels are downregulated with vascular development but upregulated in neointima that is produced in response to vascular injury. Mitogenic stimulation activates KLF5/BTEB2 gene expression through MEK1 and Egr-1. Chromatin immunoprecipitation assay showed KLF5/BTEB2 to be induced and to bind the promoter of the PDGF-A gene in response to angiotensin II stimulation. In order to define the role of KLF5/BTEB2 in cardiovascular remodeling, we targeted the KLF5/BTEB2 gene in mice. Homozygous mice resulted in early embryonic lethality whereas heterozygous mice were apparently normal. However, in response to external stress, arteries of heterozygotes exhibited diminished levels of smooth muscle and adventitial cell activation. Furthermore, cardiac fibrosis and hypertrophy induced by continuous angiotensin II infusion. We also found that RARa binds KLF5/BTEB2, and that Am80, a potent synthetic RAR agonist, inhibits angiotensin II-induced cardiac hypertrophy. These results indicate that KLF5/BTEB2 is an essential transcription factor that causes not only smooth muscle phenotypic modulation but also cardiac hypertrophy and fibrosis.

Release kinetics of circulating cardiac myosin binding protein-C following cardiac injury

PubMed Central

Kuster, Diederik W. D.; Cardenas-Ospina, Adriana; Miller, Lawson; Liebetrau, Christoph; Troidl, Christian; Nef, Holger M.; Möllmann, Helge; Hamm, Christian W.; Pieper, Karen S.; Mahaffey, Kenneth W.; Kleiman, Neal S.; Stuyvers, Bruno D.; Marian, Ali J.

2013-01-01

Diagnosis of myocardial infarction (MI) is based on ST-segment elevation on electrocardiographic evaluation and/or elevated plasma cardiac troponin (cTn) levels. However, troponins lack the sensitivity required to detect the onset of MI at its earliest stages. Therefore, to confirm its viability as an ultra-early biomarker of MI, this study investigates the release kinetics of cardiac myosin binding protein-C (cMyBP-C) in a porcine model of MI and in two human cohorts. Release kinetics of cMyBP-C were determined in a porcine model of MI (n = 6, pigs, either sex) by measuring plasma cMyBP-C level serially from 30 min to 14 days after coronary occlusion, with use of a custom-made immunoassay. cMyBP-C plasma levels were increased from baseline (76 ± 68 ng/l) at 3 h (767 ± 211 ng/l) and peaked at 6 h (2,418 ± 780 ng/l) after coronary ligation. Plasma cTnI, cTnT, and myosin light chain-3 levels were all increased 6 h after ligation. In a cohort of patients (n = 12) with hypertrophic obstructive cardiomyopathy undergoing transcoronary ablation of septal hypertrophy, cMyBP-C was significantly increased from baseline (49 ± 23 ng/l) in a time-dependent manner, peaking at 4 h (560 ± 273 ng/l). In a cohort of patients with non-ST segment elevation MI (n = 176) from the SYNERGY trial, cMyBP-C serum levels were significantly higher (7,615 ± 4,514 ng/l) than those in a control cohort (416 ± 104 ng/l; n = 153). cMyBP-C is released in the blood rapidly after cardiac damage and therefore has the potential to positively mark the onset of MI. PMID:24337456

Ad-HGF improves the cardiac remodeling of rat following myocardial infarction by upregulating autophagy and necroptosis and inhibiting apoptosis.

PubMed

Liu, Jiabao; Wu, Peng; Wang, Yunle; Du, Yingqiang; A, Nan; Liu, Shuiyuan; Zhang, Yiming; Zhou, Ningtian; Xu, Zhihui; Yang, Zhijian

2016-01-01

Cell death in MI is the most critical determinant of subsequent left ventricular remodeling and heart failure. Besides apoptosis, autophagy and necroptosis have been recently found to be another two regulated cell death styles. HGF has been reported to have a protective role in MI, but its impact on the three death styles remains unclear. Thus, our study was performed to investigate the distribution of autophagy, apoptosis and necroptosis in cardiac tissues after MI and explore the role and mechanism of Ad-HGF on cardiac remodeling by regulating the three death styles. We firstly showed the distribution of autophagy, apoptosis and necroptosis differs in temporal and spatial context after MI using immunofluorescence. Notably, Ad-HGF treatment improves the cardiac remodeling of SD rats following MI by preserving the heart function, reducing the scar size and aggresomes. Further mechanism study reveals Ad-HGF promotes autophagy and necroptosis and inhibits apoptosis in vivo and in vitro . Co-immunoprecipitation assays showed Ad-HGF treatment significantly decreased the binding of Bcl-2 to Beclin1 but enhanced Bcl-2 binding to Bax in H9c2 cells under hypoxia. Moreover, HGF-induced sequestration of Bax by Bcl-2 allows Bax to become inactive, thereby inhibiting apoptosis. In addition, Ad-HGF markedly increased the formation of Beclin1-Vps34-Atg14L complex, which accounted for promoting autophagy. Both the western blot and activity assay showed Ad-HGF significantly decreased the caspase 8 protein and activity levels, which obligated the cell to undergo necroptosis under hypoxia and block apoptosis. Thus, our findings offer new evidence and strategies for the treatment of MI and post-MI cardiac remodeling.

Ad-HGF improves the cardiac remodeling of rat following myocardial infarction by upregulating autophagy and necroptosis and inhibiting apoptosis

PubMed Central

Liu, Jiabao; Wu, Peng; Wang, Yunle; Du, Yingqiang; A, Nan; Liu, Shuiyuan; Zhang, Yiming; Zhou, Ningtian; Xu, Zhihui; Yang, Zhijian

2016-01-01

Cell death in MI is the most critical determinant of subsequent left ventricular remodeling and heart failure. Besides apoptosis, autophagy and necroptosis have been recently found to be another two regulated cell death styles. HGF has been reported to have a protective role in MI, but its impact on the three death styles remains unclear. Thus, our study was performed to investigate the distribution of autophagy, apoptosis and necroptosis in cardiac tissues after MI and explore the role and mechanism of Ad-HGF on cardiac remodeling by regulating the three death styles. We firstly showed the distribution of autophagy, apoptosis and necroptosis differs in temporal and spatial context after MI using immunofluorescence. Notably, Ad-HGF treatment improves the cardiac remodeling of SD rats following MI by preserving the heart function, reducing the scar size and aggresomes. Further mechanism study reveals Ad-HGF promotes autophagy and necroptosis and inhibits apoptosis in vivo and in vitro. Co-immunoprecipitation assays showed Ad-HGF treatment significantly decreased the binding of Bcl-2 to Beclin1 but enhanced Bcl-2 binding to Bax in H9c2 cells under hypoxia. Moreover, HGF-induced sequestration of Bax by Bcl-2 allows Bax to become inactive, thereby inhibiting apoptosis. In addition, Ad-HGF markedly increased the formation of Beclin1-Vps34-Atg14L complex, which accounted for promoting autophagy. Both the western blot and activity assay showed Ad-HGF significantly decreased the caspase 8 protein and activity levels, which obligated the cell to undergo necroptosis under hypoxia and block apoptosis. Thus, our findings offer new evidence and strategies for the treatment of MI and post-MI cardiac remodeling. PMID:27904666

Dopamine D2 receptor status assessed by IBZM SPECT - A sensitive indicator for cerebral hypoxia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tatsch, K.; Schwarz, J.; Welz, A.

1995-05-01

The striatum is highly sensitive to tissue hypoxia. Thus, it may be suggested that cerebral hypoxia could affect the integrity of the striatal receptor system. Purpose of the current SPECT investigations with IBZM was to evaluate whether hypoxic conditions cause detectable changes in the D2 receptor status. 25 controls and 30 pts with history of cerebral hypoxia (resuscitation after cardiac arrest: n=19, CABG surgery under cardiopulmonary bypass: n=11) were investigated with SPECT 2h p.i. of 185 MBq I-123 IBZM. For semiquant, evaluation transverse slices corrected for attenuation were used to calculate striatal to frontal cortex (S/FC) ratios. In 13/19 ptsmore » with cerebral hypoxia due to cardiac arrest IBZM binding was severely reduced after successful resuscitation. 7 died, 5 were in a vegetative state, 1 remained severely disabled. In 6/19 S/FC ratios were normal/mildly reduced, 2 of them had a good outcome, 4 were moderatley disabled. In pts with CABG IBZM binding was preoperatively normal. After hypoxia due to cardiac surgery striatal S/FC ratios decreased slightly, persisting on this level even 6 months after surgery. Neuropsychological/psychiatric testing showed only minor or transient changes in this group of patients. The striatal D2 receptor status seems to be a sensitive indicator for cerebral hypoxia. After hypoxia due to cardiac arrest IBZM results well correlate (in contrast to morphological or SEP findings) with the clinical outcome and thus may serve as early predictor of the individual prognosis. The moderate decline in IBZM binding following CABG surgery suggests mild cerebral hypoxia despite of protective hypothermia. Sensitively indicating cerebral hypoxia changes in the D2 receptor status assessed by IBZM SPECT may serve as a valuable diagnostic tool for testing neuroprotective drugs or modified surgical techniques.« less

Evaluation of the relationship between heart type fatty acid binding protein levels and the risk of cardiac damage in patients with obstructive sleep apnea syndrome.

PubMed

Oktay, Burcu; Akbal, Erdem; Firat, Hikmet; Ardic, Sadik; Akdemir, Ramazan; Kizilgun, Murat

2008-08-01

The aim of this study was to establish cardiac damage related to nocturnal ischemia using heart type fatty acid binding protein (h-fabp), which reaches detectable levels in plasma after being released from myocytes in case of ischemia in obstructive sleep apnea syndrome (OSAS) patients without coronary artery disease (CAD). Fifty patients diagnosed with OSAS in our sleep laboratory with polysomnographic analysis (PSG), who did not have any previous history of cardiac disease and in whom CAD was ruled out with myocardium perfusion scintigraphy, were included in the study. Control group comprised 19 volunteers without history of cardiac disease and risk factors in whom OSAS was excluded with PSG analysis. Blood samples were drawn from the patients to examine h-fabp, creatine kinase (CK), creatine kinase-MB (CK-MB), aspartate aminotransferase (AST), troponin I levels before and after sleep. No significant difference was found in CK, CK-MB, AST, Troponin I, and h-fabp levels before and after sleep in patient and control groups (p > 0.05). No significant difference was found between groups in terms of CK, CK-MB, AST, and Troponin I levels before and after sleep, while a significant difference was found between them with regard to h-fabp levels before (p = 0.006) and after sleep (p = 0.022). When arithmetical mean of the fabp levels before and after sleep was taken in the patient group, it was found that mean value of h-fabp was associated with the desaturated period in sleep which was under 80% (p = 0.04). H-fabp seems to be a marker that will enable the detection of cardiac injury in the early asymptomatic period in OSAS patients before development of disease that can be detected by imaging methods. Further studies are required to investigate the relation between the value of h-fabp and the development of cardiac dysfunction in the long term.

GSK3β phosphorylates newly identified site in the proline-alanine-rich region of cardiac myosin-binding protein C and alters cross-bridge cycling kinetics in human: short communication.

PubMed

Kuster, Diederik W D; Sequeira, Vasco; Najafi, Aref; Boontje, Nicky M; Wijnker, Paul J M; Witjas-Paalberends, E Rosalie; Marston, Steven B; Dos Remedios, Cristobal G; Carrier, Lucie; Demmers, Jeroen A A; Redwood, Charles; Sadayappan, Sakthivel; van der Velden, Jolanda

2013-02-15

Cardiac myosin-binding protein C (cMyBP-C) regulates cross-bridge cycling kinetics and, thereby, fine-tunes the rate of cardiac muscle contraction and relaxation. Its effects on cardiac kinetics are modified by phosphorylation. Three phosphorylation sites (Ser275, Ser284, and Ser304) have been identified in vivo, all located in the cardiac-specific M-domain of cMyBP-C. However, recent work has shown that up to 4 phosphate groups are present in human cMyBP-C. To identify and characterize additional phosphorylation sites in human cMyBP-C. Cardiac MyBP-C was semipurified from human heart tissue. Tandem mass spectrometry analysis identified a novel phosphorylation site on serine 133 in the proline-alanine-rich linker sequence between the C0 and C1 domains of cMyBP-C. Unlike the known sites, Ser133 was not a target of protein kinase A. In silico kinase prediction revealed glycogen synthase kinase 3β (GSK3β) as the most likely kinase to phosphorylate Ser133. In vitro incubation of the C0C2 fragment of cMyBP-C with GSK3β showed phosphorylation on Ser133. In addition, GSK3β phosphorylated Ser304, although the degree of phosphorylation was less compared with protein kinase A-induced phosphorylation at Ser304. GSK3β treatment of single membrane-permeabilized human cardiomyocytes significantly enhanced the maximal rate of tension redevelopment. GSK3β phosphorylates cMyBP-C on a novel site, which is positioned in the proline-alanine-rich region and increases kinetics of force development, suggesting a noncanonical role for GSK3β at the sarcomere level. Phosphorylation of Ser133 in the linker domain of cMyBP-C may be a novel mechanism to regulate sarcomere kinetics.

A Novel, In-solution Separation of Endogenous Cardiac Sarcomeric Proteins and Identification of Distinct Charged Variants of Regulatory Light Chain*

PubMed Central

Scruggs, Sarah B.; Reisdorph, Rick; Armstrong, Mike L.; Warren, Chad M.; Reisdorph, Nichole; Solaro, R. John; Buttrick, Peter M.

2010-01-01

The molecular conformation of the cardiac myosin motor is modulated by intermolecular interactions among the heavy chain, the light chains, myosin binding protein-C, and titin and is governed by post-translational modifications (PTMs). In-gel digestion followed by LC/MS/MS has classically been applied to identify cardiac sarcomeric PTMs; however, this approach is limited by protein size, pI, and difficulties in peptide extraction. We report a solution-based work flow for global separation of endogenous cardiac sarcomeric proteins with a focus on the regulatory light chain (RLC) in which specific sites of phosphorylation have been unclear. Subcellular fractionation followed by OFFGEL electrophoresis resulted in isolation of endogenous charge variants of sarcomeric proteins, including regulatory and essential light chains, myosin heavy chain, and myosin-binding protein-C of the thick filament. Further purification of RLC using reverse-phase HPLC separation and UV detection enriched for RLC PTMs at the intact protein level and provided a stoichiometric and quantitative assessment of endogenous RLC charge variants. Digestion and subsequent LC/MS/MS unequivocally identified that the endogenous charge variants of cardiac RLC focused in unique OFFGEL electrophoresis fractions were unphosphorylated (78.8%), singly phosphorylated (18.1%), and doubly phosphorylated (3.1%) RLC. The novel aspects of this study are that 1) milligram amounts of endogenous cardiac sarcomeric subproteome were focused with resolution comparable with two-dimensional electrophoresis, 2) separation and quantification of post-translationally modified variants were achieved at the intact protein level, 3) separation of intact high molecular weight thick filament proteins was achieved in solution, and 4) endogenous charge variants of RLC were separated; a novel doubly phosphorylated form was identified in mouse, and singly phosphorylated, singly deamidated, and deamidated/phosphorylated forms were identified and quantified in human non-failing and failing heart samples, thus demonstrating the clinical utility of the method. PMID:20445002

The Popeye domain containing genes: essential elements in heart rate control

PubMed Central

Schindler, Roland F.; Poon, Kar Lai; Simrick, Subreena

2012-01-01

The Popeye domain containing (Popdc) gene family displays preferential expression in skeletal muscle and heart. Only recently a significant gain in the understanding of the function of Popdc genes in the heart has been obtained. The Popdc genes encode membrane proteins harboring an evolutionary conserved Popeye domain, which functions as a binding domain for cyclic adenosine monophosphate (cAMP). Popdc proteins interact with the two-pore channel TREK-1 and enhance its current. This protein interaction is modulated by cAMP. Null mutations of members of the Popdc gene family in zebrafish and mouse are associated with severe cardiac arrhythmia phenotypes. While in zebrafish an atrioventricular block was prevalent, in mouse a stress-induced sinus bradycardia was observed, which was due to the presence of sinus pauses. Moreover, the phenotype develops in an age-dependent manner, being absent in the young animal and becoming increasingly severe, as the animals grow older. This phenotype is reminiscent of the sick sinus syndrome (SSS), which affects mostly the elderly and is characterized by the poor ability of the cardiac pacemaker to adapt the heart rate to the physiological demand. While being a prevalent disease, which is responsible for a large fraction of pacemaker implantations in Western countries, SSS is poorly understood at the molecular level. It is therefore expected that the study of the molecular basis of the stress-induced bradycardia in Popdc mice will shed new light on the etiology of pacemaker disease. PMID:24282731

The Popeye domain containing genes: essential elements in heart rate control.

PubMed

Schindler, Roland F; Poon, Kar Lai; Simrick, Subreena; Brand, Thomas

2012-12-01

The Popeye domain containing (Popdc) gene family displays preferential expression in skeletal muscle and heart. Only recently a significant gain in the understanding of the function of Popdc genes in the heart has been obtained. The Popdc genes encode membrane proteins harboring an evolutionary conserved Popeye domain, which functions as a binding domain for cyclic adenosine monophosphate (cAMP). Popdc proteins interact with the two-pore channel TREK-1 and enhance its current. This protein interaction is modulated by cAMP. Null mutations of members of the Popdc gene family in zebrafish and mouse are associated with severe cardiac arrhythmia phenotypes. While in zebrafish an atrioventricular block was prevalent, in mouse a stress-induced sinus bradycardia was observed, which was due to the presence of sinus pauses. Moreover, the phenotype develops in an age-dependent manner, being absent in the young animal and becoming increasingly severe, as the animals grow older. This phenotype is reminiscent of the sick sinus syndrome (SSS), which affects mostly the elderly and is characterized by the poor ability of the cardiac pacemaker to adapt the heart rate to the physiological demand. While being a prevalent disease, which is responsible for a large fraction of pacemaker implantations in Western countries, SSS is poorly understood at the molecular level. It is therefore expected that the study of the molecular basis of the stress-induced bradycardia in Popdc mice will shed new light on the etiology of pacemaker disease.

The contributions of cardiac myosin binding protein C and troponin I phosphorylation to β‐adrenergic enhancement of in vivo cardiac function

PubMed Central

Gresham, Kenneth S.

2016-01-01

Key points β‐adrenergic stimulation increases cardiac myosin binding protein C (MyBP‐C) and troponin I phosphorylation to accelerate pressure development and relaxation in vivo, although their relative contributions remain unknown.Using a novel mouse model lacking protein kinase A‐phosphorylatable troponin I (TnI) and MyBP‐C, we examined in vivo haemodynamic function before and after infusion of the β‐agonist dobutamine.Mice expressing phospho‐ablated MyBP‐C displayed cardiac hypertrophy and prevented full acceleration of pressure development and relaxation in response to dobutamine, whereas expression of phosphor‐ablated TnI alone had little effect on the acceleration of contractile function in response to dobutamine.Our data demonstrate that MyBP‐C phosphorylation is the principal mediator of the contractile response to increased β‐agonist stimulation in vivo.These results help us understand why MyBP‐C dephosphorylation in the failing heart contributes to contractile dysfunction and decreased adrenergic reserve in response to acute stress. Abstract β‐adrenergic stimulation plays a critical role in accelerating ventricular contraction and speeding relaxation to match cardiac output to changing circulatory demands. Two key myofilaments proteins, troponin I (TnI) and myosin binding protein‐C (MyBP‐C), are phosphorylated following β‐adrenergic stimulation; however, their relative contributions to the enhancement of in vivo cardiac contractility are unknown. To examine the roles of TnI and MyBP‐C phosphorylation in β‐adrenergic‐mediated enhancement of cardiac function, transgenic (TG) mice expressing non‐phosphorylatable TnI protein kinase A (PKA) residues (i.e. serine to alanine substitution at Ser23/24; TnIPKA−) were bred with mice expressing non‐phosphorylatable MyBP‐C PKA residues (i.e. serine to alanine substitution at Ser273, Ser282 and Ser302; MyBPCPKA−) to generate a novel mouse model expressing non‐phosphorylatable PKA residues in TnI and MyBP‐C (DBLPKA−). MyBP‐C dephosphorylation produced cardiac hypertrophy and increased wall thickness in MyBPCPKA− and DBLPKA− mice, and in vivo echocardiography and pressure–volume catheterization studies revealed impaired systolic function and prolonged diastolic relaxation compared to wild‐type and TnIPKA– mice. Infusion of the β‐agonist dobutamine resulted in accelerated rates of pressure development and relaxation in all mice; however, MyBPCPKA− and DBLPKA− mice displayed a blunted contractile response compared to wild‐type and TnIPKA– mice. Furthermore, unanaesthesized MyBPCPKA− and DBLPKA− mice displayed depressed maximum systolic pressure in response to dobutamine as measured using implantable telemetry devices. Taken together, our data show that MyBP‐C phosphorylation is a critical modulator of the in vivo acceleration of pressure development and relaxation as a result of enhanced β‐adrenergic stimulation, and reduced MyBP‐C phosphorylation may underlie depressed adrenergic reserve in heart failure. PMID:26635197

Cardiac integrins the ties that bind.

PubMed

Simpson, D G; Reaves, T A; Shih, D T; Burgess, W; Borg, T K; Terracio, L

1998-01-01

An elaborate series of morphogenetic events must be precisely coordinated during development to promote the formation of the elaborate three-dimensional structure of the normal heart. In this study we focus on discussing how interconnections between the cardiac myocyte and its surrounding environment regulate cardiac form and function. In vitro experiments from our laboratories provide direct evidence that cardiac cell shape is regulated by a dynamic interaction between constituents of the extracellular matrix (ECM) and by specific members of the integrin family of matrix receptors. Our data indicates that phenotypic information is stored in the tertiary structure and chemical identity of the ECM. This information appears to be actively communicated and transduced by the α1β1 integrin molecule into an intracellular signal that regulates cardiac cell shape and myofibrillar organization. In this study we have assessed the phenotypic consequences of suppressing the expression and accumulation of the α1 integrin molecule in aligned cultures of cardiac myocytes. In related experiments we have examined how the overexpression of α2 and α5 integrin, integrins normally not present or present at very low copy number on the cell surface of neonatal cardiac myocytes, affect cardiac protein metabolism. We also consider how biochemical signals and the mechanical signals mediated by the integrins may converge on common intracellular signaling pathways in the heart. Experiments with the whole embryo culture system indicate that angiotensin II, a peptide that carries information concerning cardiac load, plays a role in controling cardiac looping and the proliferation of myofibrils during development.

An incoherent feedforward loop facilitates adaptive tuning of gene expression.

PubMed

Hong, Jungeui; Brandt, Nathan; Abdul-Rahman, Farah; Yang, Ally; Hughes, Tim; Gresham, David

2018-04-05

We studied adaptive evolution of gene expression using long-term experimental evolution of Saccharomyces cerevisiae in ammonium-limited chemostats. We found repeated selection for non-synonymous variation in the DNA binding domain of the transcriptional activator, GAT1, which functions with the repressor, DAL80 in an incoherent type-1 feedforward loop (I1-FFL) to control expression of the high affinity ammonium transporter gene, MEP2. Missense mutations in the DNA binding domain of GAT1 reduce its binding to the GATAA consensus sequence. However, we show experimentally, and using mathematical modeling, that decreases in GAT1 binding result in increased expression of MEP2 as a consequence of properties of I1-FFLs. Our results show that I1-FFLs, one of the most commonly occurring network motifs in transcriptional networks, can facilitate adaptive tuning of gene expression through modulation of transcription factor binding affinities. Our findings highlight the importance of gene regulatory architectures in the evolution of gene expression. © 2018, Hong et al.

Effect of hypokinesia on cardiac contractile function and nervous regulation of the heart

NASA Technical Reports Server (NTRS)

Meyerson, F. Z.; Kapelko, V. I.; Gorina, M. S.; Shchegolkov, A. N.; Larinov, N. P.

1980-01-01

Longterm hypokinesia caused cardiac deadaptation in rabbits, which resulted in the diminishing of the left ventricular rate of contraction and relaxation, joined later by decreased vascular resistance. As a results, the ejection rate as well as stroke volume and cardiac output were normal. The decrease of the relaxation speed was more obvious at a high heart rate and results in shortening of the diastolic pause and diminishing of cardiac output. Hearts of the hypokinetic animals were characterized by normal maximal pressure developed by a unit of muccardial mass aorta clamping, decreased adrenoreactivity, and increased cholinoreactivity. This complex of changes is contrary to changes observed in adaptation to exercise, but is similar to changes observed in compensatory hypertrophy of the heart.

Both endothelin-A and endothelin-B receptors are present on adult rat cardiac ventricular myocytes.

PubMed

Allen, Bruce G; Phuong, Luu Lien; Farhat, Hala; Chevalier, Dominique

2003-02-01

Endothelin-A (ET(A)) and endothelin-B (ET(B)) receptors have been demonstrated in intact heart and cardiac membranes. ET(A) receptors have been demonstrated on adult ventricular myocytes. The aim of the present study was to determine the presence of ET(B) and the relative contribution of this receptor subtype to total endothelin-1 (ET-1) binding on adult ventricular myocytes. Saturation binding experiments indicated that ET-1 bound to a single population of receptors (Kd = 0.52 +/- 0.13 nM, n = 4) with an apparent maximum binding (Bmax) of 2.10 +/- 0.25 sites (x 10(5))/cell (n = 4). Competition experiments using 40 pM [125I]ET-1 and nonradioactive ET-1 revealed a Ki of 660 +/- 71 pM (n = 10) and a Hill coefficient (nH) of 0.99 +/- 0.10 (n = 10). A selective ET(A) antagonist, BQ610, displaced 80% of the bound [125I]ET-1. No displacement was observed by concentrations of an ET(B)-selective antagonist, BQ788, up to 1.0 microM. However, in the presence of 1.0 microM BQ610, BQ788 inhibited the remaining [125I]ET-1 binding. Similarly, in the presence of 1.0 microM BQ788, BQ610 inhibited the remaining specific [125I]ET-1 binding. Binding of an ET(B1)-selective agonist, [125I]IRL-1620, confirmed the presence of ET(B). ET(B) bound to ET-1 irreversibly, whereas binding to ET(A) demonstrated both reversible and irreversible components, and BQ610 and BQ788 bound reversibly. Reducing the incubation temperature to 0 degrees C did not alter the irreversible component of ET-1 binding. Hence, both ET(A) and ET(B) receptors are present on intact adult rat ventricular myocytes, and the ratio of ET(A):ET(B) binding sites is 4:1. Both receptor subtypes bind to ET-1 by a two-step association involving the formation of a tight receptor-ligand complex; however, the kinetics of ET-1 binding to ET(A) versus ET(B) differ.

Comparative Effects of Oral Chlorpyrifos Exposure on Cholinesterase Activity and Muscarinic Receptor Binding in Neonatal and Adult Rat Heart

PubMed Central

Howard, Marcia D.; Mirajkar, Nikita; Karanth, Subramanya; Pope, Carey N.

2010-01-01

Organophosphorus (OP) pesticides elicit acute toxicity by inhibiting acetylcholinesterase (AChE), the enzyme responsible for inactivating acetylcholine (ACh) at cholinergic synapses. A number of OP toxicants have also been reported to interact directly with muscarinic receptors, in particular the M2 muscarinic subtype. Parasympathetic innervation to the heart primarily regulates cardiac function by activating M2 receptors in the sinus node, atrial-ventricular node and conducting tissues. Thus, OP insecticides can potentially influence cardiac function in a receptor–mediated manner indirectly by inhibiting acetylcholinesterase and directly by binding to muscarinic M2 receptors. Young animals are generally more sensitive than adults to the acute toxicity of OP insecticides and age related differences in potency of direct binding to muscarinic receptors by some OP toxicants have been reported. We thus compared the effects of the common OP insecticide chlorpyrifos (CPF) on functional signs of toxicity and cardiac ChE activity and muscarinic receptor binding in neonatal and adult rats. Dosages were based on acute lethality (i.e., 0.5 and 1 × LD10: neonates, 7.5 and 15 mg/kg; adults, 68 and 136 mg/kg). Dose- and time-related changes in body weight and cholinergic signs of toxicity (involuntary movements) were noted in both age groups. With 1 × LD10, relatively similar maximal reductions in ChE activity (95%) and muscarinic receptor binding (≈ 30%) were noted, but receptor binding reductions appeared earlier in adults and were more prolonged in neonates. In vitro inhibition studies indicated that ChE in neonatal tissues was markedly more sensitive to inhibition by the active metabolite of chlorpyrifos (i.e., chlorpyrifos oxon, CPO) than enzyme in adult tissues (IC50 values: neonates, 17 nM; adults, 200 nM). Chelation of free calcium with EDTA had relatively little effect on in vitro cholinesterase inhibition, suggesting that differential A-esterase activity was not responsible for the age-related difference in cholinesterase sensitivity between age groups. Pre-incubation of neonatal and adult tissues with selective inhibitors of AChE and butyrylcholinesterase (BChE) indicated that a majority (82–90%) of ChE activity in the heart of both neonates and adults was BChE. The rapid onset (by 4 hours after dosing) of changes in muscarinic receptor binding in adult heart may be a reflection of the more potent direct binding to muscarinic receptors by chlorpyrifos oxon previously reported in adult tissues. The results suggest that ChE activity (primarily BChE) in neonatal heart may be inherently more sensitive to inhibition by some anticholinesterases and that toxicologically significant binding to muscarinic receptors may be possible with acute chlorpyrifos intoxication, potentially contributing to age-related differences in sensitivity. PMID:17644233

Heart failure drug changes the mechanoenzymology of the cardiac myosin powerstroke.

PubMed

Rohde, John A; Thomas, David D; Muretta, Joseph M

2017-03-07

Omecamtiv mecarbil (OM), a putative heart failure therapeutic, increases cardiac contractility. We hypothesize that it does this by changing the structural kinetics of the myosin powerstroke. We tested this directly by performing transient time-resolved FRET on a ventricular cardiac myosin biosensor. Our results demonstrate that OM stabilizes myosin's prepowerstroke structural state, supporting previous measurements showing that the drug shifts the equilibrium constant for myosin-catalyzed ATP hydrolysis toward the posthydrolysis biochemical state. OM slowed the actin-induced powerstroke, despite a twofold increase in the rate constant for actin-activated phosphate release, the biochemical step in myosin's ATPase cycle associated with force generation and the conversion of chemical energy into mechanical work. We conclude that OM alters the energetics of cardiac myosin's mechanical cycle, causing the powerstroke to occur after myosin weakly binds to actin and releases phosphate. We discuss the physiological implications for these changes.

The ATP-sensitive potassium (KATP) channel-encoded dSUR gene is required for Drosophila heart function and is regulated by tinman

PubMed Central

Akasaka, Takeshi; Klinedinst, Susan; Ocorr, Karen; Bustamante, Erika L.; Kim, Seung K.; Bodmer, Rolf

2006-01-01

The homeobox transcription factor Tinman plays an important role in the initiation of heart development. Later functions of Tinman, including the target genes involved in cardiac physiology, are less well studied. We focused on the dSUR gene, which encodes an ATP-binding cassette transmembrane protein that is expressed in the heart. Mammalian SUR genes are associated with KATP (ATP-sensitive potassium) channels, which are involved in metabolic homeostasis. We provide experimental evidence that Tinman directly regulates dSUR expression in the developing heart. We identified a cis-regulatory element in the first intron of dSUR, which contains Tinman consensus binding sites and is sufficient for faithful dSUR expression in the fly’s myocardium. Site-directed mutagenesis of this element shows that these Tinman sites are critical to dSUR expression, and further genetic manipulations suggest that the GATA transcription factor Pannier is synergistically involved in cardiac-restricted dSUR expression in vivo. Physiological analysis of dSUR knock-down flies supports the idea that dSUR plays a protective role against hypoxic stress and pacing-induced heart failure. Because dSUR expression dramatically decreases with age, it is likely to be a factor involved in the cardiac aging phenotype of Drosophila. dSUR provides a model for addressing how embryonic regulators of myocardial cell commitment can contribute to the establishment and maintenance of cardiac performance. PMID:16882722

Alpha 1-acid glycoprotein reverses cocaine-induced sodium channel blockade in cardiac myocytes.

PubMed

Ma, Yu-Ling; Peters, Nicholas S; Henry, John A

2006-03-01

Alpha 1-acid glycoprotein (AAG) is an acute phase protein capable of binding basic drugs. This action explains its reversal of sodium channel blockade by drugs such as amitriptyline and quinidine. We report here the reversal of cocaine-induced sodium channel blockade by AAG. The sodium channel blocking property of cocaine is a major mechanism behind cocaine-induced sudden cardiac death, since sodium channels play a key role in the initiation and regulation of the heart beat. Voltage-gated sodium current (I(Na)) was recorded using whole-cell patch-clamp techniques. Guinea-pig cardiac ventricular myocytes were isolated and continuously perfused at room temperature with physiological solutions. At concentrations ranging from 5 to 320 microM cocaine showed a dose-dependent and reversible blockade of I(Na) with an IC50 of 45.9 microM. The addition of equimolar amounts of AAG to cocaine produced almost complete reversal of cocaine's effects, suggesting a single binding site for cocaine on the AAG molecule. With changes of peak I(Na) normalized against control as 1, cocaine at 20 and 40 microM reduced I(Na) to 0.62+/-0.042 (n = 6) and 0.57+/-0.052 (n = 9), respectively, and the addition of an equimolar concentration of AAG reversed I(Na) to 0.86+/-0.022 and 0.91+/-0.060, respectively. AAG reverses cocaine-induced sodium channel blockade in a dose-dependent manner, indicating a therapeutic potential to reverse acute cocaine cardiac toxicity.

Titin isoform switching is a major cardiac adaptive response in hibernating grizzly bears.

PubMed

Nelson, O Lynne; Robbins, Charles T; Wu, Yiming; Granzier, Henk

2008-07-01

The hibernation phenomenon captures biological as well as clinical interests to understand how organs adapt. Here we studied how hibernating grizzly bears (Ursus arctos horribilis) tolerate extremely low heart rates without developing cardiac chamber dilation. We evaluated cardiac filling function in unanesthetized grizzly bears by echocardiography during the active and hibernating period. Because both collagen and titin are involved in altering diastolic function, we investigated both in the myocardium of active and hibernating grizzly bears. Heart rates were reduced from 84 beats/min in active bears to 19 beats/min in hibernating bears. Diastolic volume, stroke volume, and left ventricular ejection fraction were not different. However, left ventricular muscle mass was significantly lower (300 +/- 12 compared with 402 +/- 14 g; P = 0.003) in the hibernating bears, and as a result the diastolic volume-to-left ventricular muscle mass ratio was significantly greater. Early ventricular filling deceleration times (106.4 +/- 14 compared with 143.2 +/- 20 ms; P = 0.002) were shorter during hibernation, suggesting increased ventricular stiffness. Restrictive pulmonary venous flow patterns supported this conclusion. Collagen type I and III comparisons did not reveal differences between the two groups of bears. In contrast, the expression of titin was altered by a significant upregulation of the stiffer N2B isoform at the expense of the more compliant N2BA isoform. The mean ratio of N2BA to N2B titin was 0.73 +/- 0.07 in the active bears and decreased to 0.42 +/- 0.03 (P = 0.006) in the hibernating bears. The upregulation of stiff N2B cardiac titin is a likely explanation for the increased ventricular stiffness that was revealed by echocardiography, and we propose that it plays a role in preventing chamber dilation in hibernating grizzly bears. Thus our work identified changes in the alternative splicing of cardiac titin as a major adaptive response in hibernating grizzly bears.

Characterization of the Cardiac Overexpression of HSPB2 Reveals Mitochondrial and Myogenic Roles Supported by a Cardiac HspB2 Interactome.

PubMed

Grose, Julianne H; Langston, Kelsey; Wang, Xiaohui; Squires, Shayne; Mustafi, Soumyajit Banerjee; Hayes, Whitney; Neubert, Jonathan; Fischer, Susan K; Fasano, Matthew; Saunders, Gina Moore; Dai, Qiang; Christians, Elisabeth; Lewandowski, E Douglas; Ping, Peipei; Benjamin, Ivor J

2015-01-01

Small Heat Shock Proteins (sHSPs) are molecular chaperones that transiently interact with other proteins, thereby assisting with quality control of proper protein folding and/or degradation. They are also recruited to protect cells from a variety of stresses in response to extreme heat, heavy metals, and oxidative-reductive stress. Although ten human sHSPs have been identified, their likely diverse biological functions remain an enigma in health and disease, and much less is known about non-redundant roles in selective cells and tissues. Herein, we set out to comprehensively characterize the cardiac-restricted Heat Shock Protein B-2 (HspB2), which exhibited ischemic cardioprotection in transgenic overexpressing mice including reduced infarct size and maintenance of ATP levels. Global yeast two-hybrid analysis using HspB2 (bait) and a human cardiac library (prey) coupled with co-immunoprecipitation studies for mitochondrial target validation revealed the first HspB2 "cardiac interactome" to contain many myofibril and mitochondrial-binding partners consistent with the overexpression phenotype. This interactome has been submitted to the Biological General Repository for Interaction Datasets (BioGRID). A related sHSP chaperone HspB5 had only partially overlapping binding partners, supporting specificity of the interactome as well as non-redundant roles reported for these sHSPs. Evidence that the cardiac yeast two-hybrid HspB2 interactome targets resident mitochondrial client proteins is consistent with the role of HspB2 in maintaining ATP levels and suggests new chaperone-dependent functions for metabolic homeostasis. One of the HspB2 targets, glyceraldehyde 3-phosphate dehydrogenase (GAPDH), has reported roles in HspB2 associated phenotypes including cardiac ATP production, mitochondrial function, and apoptosis, and was validated as a potential client protein of HspB2 through chaperone assays. From the clientele and phenotypes identified herein, it is tempting to speculate that small molecule activators of HspB2 might be deployed to mitigate mitochondrial related diseases such as cardiomyopathy and neurodegenerative disease.

Cardiac elastography: detecting pathological changes in myocardium tissues

NASA Astrophysics Data System (ADS)

Konofagou, Elisa E.; Harrigan, Timothy; Solomon, Scott

2003-05-01

Estimation of the mechanical properties of the cardiac muscle has been shown to play a crucial role in the detection of cardiovascular disease. Elastography was recently shown feasible on RF cardiac data in vivo. In this paper, the role of elastography in the detection of ischemia/infarct is explored with simulations and in vivo experiments. In finite-element simulations of a portion of the cardiac muscle containing an infarcted region, the cardiac cycle was simulated with successive compressive and tensile strains ranging between -30% and 20%. The incremental elastic modulus was also mapped uisng adaptive methods. We then demonstrated this technique utilizing envelope-detected sonographic data (Hewlett-Packard Sonos 5500) in a patient with a known myocardial infarction. In cine-loop and M-Mode elastograms from both normal and infarcted regions in simulations and experiments, the infarcted region was identifed by the up to one order of magnitude lower incremental axial displacements and strains, and higher modulus. Information on motion, deformation and mechanical property should constitute a unique tool for noninvasive cardiac diagnosis.

Characterization of Zebrafish Cardiac and Slow Skeletal Troponin C Paralogs by MD Simulation and ITC.

PubMed

Stevens, Charles M; Rayani, Kaveh; Genge, Christine E; Singh, Gurpreet; Liang, Bo; Roller, Janine M; Li, Cindy; Li, Alison Yueh; Tieleman, D Peter; van Petegem, Filip; Tibbits, Glen F

2016-07-12

Zebrafish, as a model for teleost fish, have two paralogous troponin C (TnC) genes that are expressed in the heart differentially in response to temperature acclimation. Upon Ca(2+) binding, TnC changes conformation and exposes a hydrophobic patch that interacts with troponin I and initiates cardiac muscle contraction. Teleost-specific TnC paralogs have not yet been functionally characterized. In this study we have modeled the structures of the paralogs using molecular dynamics simulations at 18°C and 28°C and calculated the different Ca(2+)-binding properties between the teleost cardiac (cTnC or TnC1a) and slow-skeletal (ssTnC or TnC1b) paralogs through potential-of-mean-force calculations. These values are compared with thermodynamic binding properties obtained through isothermal titration calorimetry (ITC). The modeled structures of each of the paralogs are similar at each temperature, with the exception of helix C, which flanks the Ca(2+) binding site; this region is also home to paralog-specific sequence substitutions that we predict have an influence on protein function. The short timescale of the potential-of-mean-force calculation precludes the inclusion of the conformational change on the ΔG of Ca(2+) interaction, whereas the ITC analysis includes the Ca(2+) binding and conformational change of the TnC molecule. ITC analysis has revealed that ssTnC has higher Ca(2+) affinity than cTnC for Ca(2+) overall, whereas each of the paralogs has increased affinity at 28°C compared to 18°C. Microsecond-timescale simulations have calculated that the cTnC paralog transitions from the closed to the open state more readily than the ssTnC paralog, an unfavorable transition that would decrease the ITC-derived Ca(2+) affinity while simultaneously increasing the Ca(2+) sensitivity of the myofilament. We propose that the preferential expression of cTnC at lower temperatures increases myofilament Ca(2+) sensitivity by this mechanism, despite the lower Ca(2+) affinity that we have measured by ITC. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Modulation of gene expression in heart and liver of hibernating black bears (Ursus americanus)

PubMed Central

2011-01-01

Background Hibernation is an adaptive strategy to survive in highly seasonal or unpredictable environments. The molecular and genetic basis of hibernation physiology in mammals has only recently been studied using large scale genomic approaches. We analyzed gene expression in the American black bear, Ursus americanus, using a custom 12,800 cDNA probe microarray to detect differences in expression that occur in heart and liver during winter hibernation in comparison to summer active animals. Results We identified 245 genes in heart and 319 genes in liver that were differentially expressed between winter and summer. The expression of 24 genes was significantly elevated during hibernation in both heart and liver. These genes are mostly involved in lipid catabolism and protein biosynthesis and include RNA binding protein motif 3 (Rbm3), which enhances protein synthesis at mildly hypothermic temperatures. Elevated expression of protein biosynthesis genes suggests induction of translation that may be related to adaptive mechanisms reducing cardiac and muscle atrophies over extended periods of low metabolism and immobility during hibernation in bears. Coordinated reduction of transcription of genes involved in amino acid catabolism suggests redirection of amino acids from catabolic pathways to protein biosynthesis. We identify common for black bears and small mammalian hibernators transcriptional changes in the liver that include induction of genes responsible for fatty acid β oxidation and carbohydrate synthesis and depression of genes involved in lipid biosynthesis, carbohydrate catabolism, cellular respiration and detoxification pathways. Conclusions Our findings show that modulation of gene expression during winter hibernation represents molecular mechanism of adaptation to extreme environments. PMID:21453527

Pharmacological targeting of CDK9 in cardiac hypertrophy.

PubMed

Krystof, Vladimír; Chamrád, Ivo; Jorda, Radek; Kohoutek, Jirí

2010-07-01

Cardiac hypertrophy allows the heart to adapt to workload, but persistent or unphysiological stimulus can result in pump failure. Cardiac hypertrophy is characterized by an increase in the size of differentiated cardiac myocytes. At the molecular level, growth of cells is linked to intensive transcription and translation. Several cyclin-dependent kinases (CDKs) have been identified as principal regulators of transcription, and among these CDK9 is directly associated with cardiac hypertrophy. CDK9 phosphorylates the C-terminal domain of RNA polymerase II and thus stimulates the elongation phase of transcription. Chronic activation of CDK9 causes not only cardiac myocyte enlargement but also confers predisposition to heart failure. Due to the long interest of molecular oncologists and medicinal chemists in CDKs as potential targets of anticancer drugs, a portfolio of small-molecule inhibitors of CDK9 is available. Recent determination of CDK9's crystal structure now allows the development of selective inhibitors and their further optimization in terms of biochemical potency and selectivity. CDK9 may therefore constitute a novel target for drugs against cardiac hypertrophy.

A novel comparative pattern count analysis reveals a chronic ethanol-induced dynamic shift in immediate early NF-κB genome-wide promoter binding during liver regeneration.

PubMed

Kuttippurathu, Lakshmi; Patra, Biswanath; Hoek, Jan B; Vadigepalli, Rajanikanth

2016-03-01

Liver regeneration after partial hepatectomy is a clinically important process that is impaired by adaptation to chronic alcohol intake. We focused on the initial time points following partial hepatectomy (PHx) to analyze the genome-wide binding activity of NF-κB, a key immediate early regulator. We investigated the effect of chronic alcohol intake on immediate early NF-κB genome-wide localization, in the adapted state as well as in response to partial hepatectomy, using chromatin immunoprecipitation followed by promoter microarray analysis. We found many ethanol-specific NF-κB binding target promoters in the ethanol-adapted state, corresponding to the regulation of biosynthetic processes, oxidation-reduction and apoptosis. Partial hepatectomy induced a diet-independent shift in NF-κB binding loci relative to the transcription start sites. We employed a novel pattern count analysis to exhaustively enumerate and compare the number of promoters corresponding to the temporal binding patterns in ethanol and pair-fed control groups. The highest pattern count corresponded to promoters with NF-κB binding exclusively in the ethanol group at 1 h post PHx. This set was associated with the regulation of cell death, response to oxidative stress, histone modification, mitochondrial function, and metabolic processes. Integration with the global gene expression profiles to identify putative transcriptional consequences of NF-κB binding patterns revealed that several of ethanol-specific 1 h binding targets showed ethanol-specific differential expression through 6 h post PHx. Motif analysis yielded co-incident binding loci for STAT3, AP-1, CREB, C/EBP-β, PPAR-γ and C/EBP-α, likely participating in co-regulatory modules with NF-κB in shaping the immediate early response to PHx. We conclude that adaptation to chronic ethanol intake disrupts the NF-κB promoter binding landscape with consequences for the immediate early gene regulatory response to the acute challenge of PHx.

/sup 3/H)pirenzepine and (-)-(/sup 3/H)quinuclidinyl benzilate binding to rat cerebral cortical and cardiac muscarinic cholinergic sites. I. Characterization and regulation of agonist binding to putative muscarinic subtypes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watson, M.; Yamamura, H.I.; Roeske, W.R.

The binding and regulation of selected muscarinic agonists to putative subtypes in rat cerebral cortex and heart were studied. Parallel inhibition studies of (/sup 3/H)pirenzepine ((/sup 3/H)PZ) and (-)-(/sup 3/H)quinuclidinylbenzilate ((-)-(/sup 3/H)QNB)-labeled membranes were done with and without 30 microM guanyl-5'-yl imidodiphosphate (Gpp(NH)p) at 25 degrees C in 10 mM Na-K-phosphate buffer which enhances PZ binding affinity and in modified Krebs-phosphate buffer, which mimics physiological conditions. Classical agonists such as carbachol, oxotremorine and acetylcholine inhibited (-)-(/sup 3/H)QNB binding to membranes with shallow Hill values (nH less than 1), were better fit to a 2-state model, were Gpp(NH)p-regulated and showed lowermore » affinity in modified Krebs-phosphate buffer than in 10 mM Na-K-phosphate buffer. Some agonists were not significantly better fit to a 2-state model in (/sup 3/H)PZ-labeled cortical membranes, especially in 10 mM Na-K-phosphate buffer. Whereas putative M1 and M2 binding sites distinguished by PZ possessed multiple agonist affinity states, as judged by carbachol, and agonist binding to (/sup 3/H)PZ-labeled sites were Gpp(NH)p modulated, the partial agonist pilocarpine and nonclassical agonist McN-A-343 (3-(m-chlorophenylcarbamoyloxy)-2-butynyl trimethylammonium chloride) showed little Gpp(NH)p-induced shift in (/sup 3/H)PZ-labeled cortical membranes in physiological conditions. Agonist binding to (-)-(/sup 3/H)QNB-labeled putative M2 cardiac sites was more sensitive to Gpp(NH)p than (-)-(/sup 3/H)QNB-labeled cortical sites. Carbachol and acetylcholine showed significant selectivity for putative M2 sites.« less

Biomarkers and mortality after transient ischemic attack and minor ischemic stroke: population-based study.

PubMed

Greisenegger, Stefan; Segal, Helen C; Burgess, Annette I; Poole, Debbie L; Mehta, Ziyah; Rothwell, Peter M

2015-03-01

Premature death after transient ischemic attack or stroke is more often because of heart disease or cancer than stroke. Previous studies found blood biomarkers not usefully predictive of nonfatal stroke but possibly of all-cause death. This association might be explained by potentially treatable occult cardiac disease or cancer. We therefore aimed to validate the association of a panel of biomarkers with all-cause death, particularly cardiac death and cancer death, despite the absence of associations with risk of nonfatal vascular events. Fifteen biomarkers were measured in 929 consecutive patients in a population-based study (Oxford Vascular Study), recruited from 2002 and followed up to 2013. Associations were determined by Cox regression. Model discrimination was assessed by c-statistic and the integrated discrimination improvement. During 5560 patient-years of follow-up, none of the biomarkers predicted risk of nonfatal vascular events. However, soluble tumor necrosis factor α receptor-1, von Willebrand factor, heart-type fatty-acid-binding protein, and N-terminal pro-B-type natriuretic peptide were independently predictive of all-cause death (n=361; adjusted hazard ratio per SD, 95% confidence interval: heart-type fatty-acid-binding protein: 1.31, 1.12-1.56, P=0.002; N-terminal pro-B-type natriuretic peptide: 1.34, 1.11-1.62, P=0.002; soluble tumor necrosis factor α receptor-1: 1.45, 1.26-1.66, P=0.02; von Willebrand factor: 1.19, 1.04-1.36, P=0.01). The independent contribution of the four biomarkers taken together added prognostic information and improved model discrimination (integrated discrimination improvement=0.028, P=0.0001). N-terminal pro-B-type natriuretic peptide was most predictive of vascular death (adjusted hazard ratio=1.80, 95% confidence interval, 1.34-2.41, P<0.0001), whereas heart-type fatty-acid-binding protein predicted cancer deaths (1.64, 1.26-2.12, P=0.0002). Associations were strongest in patients without known prior cardiac disease or cancer. Several biomarkers predicted death of any cause after transient ischemic attack and minor stroke. N-terminal pro-B-type natriuretic peptide and heart-type fatty-acid-binding protein might improve patient selection for additional screening for occult cardiac disease or cancer, respectively. However, our results require validation in future studies. © 2015 American Heart Association, Inc.

3D cardiac μ tissues within a microfluidic device with real-time contractile stress readout

PubMed Central

Aung, Aereas; Bhullar, Ivneet Singh; Theprungsirikul, Jomkuan; Davey, Shruti Krishna; Lim, Han Liang; Chiu, Yu-Jui; Ma, Xuanyi; Dewan, Sukriti; Lo, Yu-Hwa; McCulloch, Andrew; Varghese, Shyni

2015-01-01

We present the development of three-dimensional (3D) cardiac microtissues within a microfluidic device with the ability to quantify real-time contractile stress measurements in situ. Using a 3D patterning technology that allows for the precise spatial distribution of cells within the device, we created an array of 3D cardiac microtissues from neonatal mouse cardiomyocytes. We integrated the 3D micropatterning technology with microfluidics to achieve perfused cell-laden structures. The cells were encapsulated within a degradable gelatin methacrylate hydrogel, which was sandwiched between two polyacrylamide hydrogels. The polyacrylamide hydrogels were used as “stress sensors” to acquire the contractile stresses generated by the beating cardiac cells. The cardiac-specific response of the engineered 3D system was examined by exposing it to epinephrine, an adrenergic neurotransmitter known to increase the magnitude and frequency of cardiac contractions. In response to exogenous epinephrine the engineered cardiac tissues exhibited an increased beating frequency and stress magnitude. Such cost-effective and easy-to-adapt 3D cardiac systems with real-time functional readout could be an attractive technological platform for drug discovery and development. PMID:26588203

Team-focused Cardiopulmonary Resuscitation: Prehospital Principles Adapted for Emergency Department Cardiac Arrest Resuscitation.

PubMed

Johnson, Blake; Runyon, Michael; Weekes, Anthony; Pearson, David

2018-01-01

Out-of-hospital cardiac arrest has high rates of morbidity and mortality, and a growing body of evidence is redefining our approach to the resuscitation of these high-risk patients. Team-focused cardiopulmonary resuscitation (TFCPR), most commonly deployed and described by prehospital care providers, is a focused approach to cardiac arrest care that emphasizes early defibrillation and high-quality, minimally interrupted chest compressions while de-emphasizing endotracheal intubation and intravenous drug administration. TFCPR is associated with statistically significant increases in survival to hospital admission, survival to hospital discharge, and survival with good neurologic outcome; however, the adoption of similar streamlined resuscitation approaches by emergency physicians has not been widely reported. In the absence of a deliberately streamlined approach, such as TFCPR, other advanced therapies and procedures that have not shown similar survival benefit may be prioritized at the expense of simpler evidence-based interventions. This review examines the current literature on cardiac arrest resuscitation. The recent prehospital success of TFCPR is highlighted, including the associated improvements in multiple patient-centered outcomes. The adaptability of TFCPR to the emergency department (ED) setting is also discussed in detail. Finally, we discuss advanced interventions frequently performed during ED cardiac arrest resuscitation that may interfere with early defibrillation and effective high-quality chest compressions. TFCPR has been associated with improved patient outcomes in the prehospital setting. The data are less compelling for other commonly used advanced resuscitation tools and procedures. Emergency physicians should consider incorporating the TFCPR approach into ED cardiac arrest resuscitation to optimize delivery of those interventions most associated with improved outcomes. Copyright © 2017 Elsevier Inc. All rights reserved.

Single cardiac ventricular myosins are autonomous motors

PubMed Central

Wang, Yihua; Yuan, Chen-Ching; Kazmierczak, Katarzyna; Szczesna-Cordary, Danuta

2018-01-01

Myosin transduces ATP free energy into mechanical work in muscle. Cardiac muscle has dynamically wide-ranging power demands on the motor as the muscle changes modes in a heartbeat from relaxation, via auxotonic shortening, to isometric contraction. The cardiac power output modulation mechanism is explored in vitro by assessing single cardiac myosin step-size selection versus load. Transgenic mice express human ventricular essential light chain (ELC) in wild- type (WT), or hypertrophic cardiomyopathy-linked mutant forms, A57G or E143K, in a background of mouse α-cardiac myosin heavy chain. Ensemble motility and single myosin mechanical characteristics are consistent with an A57G that impairs ELC N-terminus actin binding and an E143K that impairs lever-arm stability, while both species down-shift average step-size with increasing load. Cardiac myosin in vivo down-shifts velocity/force ratio with increasing load by changed unitary step-size selections. Here, the loaded in vitro single myosin assay indicates quantitative complementarity with the in vivo mechanism. Both have two embedded regulatory transitions, one inhibiting ADP release and a second novel mechanism inhibiting actin detachment via strain on the actin-bound ELC N-terminus. Competing regulators filter unitary step-size selection to control force-velocity modulation without myosin integration into muscle. Cardiac myosin is muscle in a molecule. PMID:29669825

Mechanisms of epigenetic and cell-type specific regulation of Hey target genes in ES cells and cardiomyocytes.

PubMed

Weber, David; Heisig, Julia; Kneitz, Susanne; Wolf, Elmar; Eilers, Martin; Gessler, Manfred

2015-02-01

Hey bHLH transcription factors are critical effectors of Notch signaling. During mammalian heart development they are expressed in atrial and ventricular cardiomyocytes and in the developing endocardium. Hey knockout mice suffer from lethal cardiac defects, such as ventricular septum defects, valve defects and cardiomyopathy. Despite this functional relevance, little is known about the regulation of downstream targets in relevant cell types. The objective of this study was to elucidate the regulatory mechanisms by which Hey proteins affect gene expression in a cell type specific manner. We used an in vitro cardiomyocyte differentiation system with inducible Hey1 or Hey2 expression to study target gene regulation in cardiomyocytes (CM) generated from murine embryonic stem cells (ESC). The effects of Hey1 and Hey2 are largely redundant, but cell type specific. The number of regulated genes is comparable between ESC and CM, but the total number of binding sites is much higher, especially in ESC, targeting mainly genes involved in transcriptional regulation and developmental processes. Repression by Hey proteins generally correlates with the extent of Hey-binding to target promoters, Hdac recruitment and lower histone acetylation. Functionally, treatment with the Hdac inhibitor TSA abolished Hey target gene regulation. However, in CM the repressive effect of Hey-binding is lost for a subset of genes. These also lack Hey-dependent histone deacetylation in CM and are enriched for binding sites of cardiac specific activators like Srf, Nkx2-5, and Gata4. Ectopic Nkx2-5 overexpression in ESC blocks Hey-mediated repression of these genes. Thus, Hey proteins mechanistically repress target genes via Hdac recruitment and histone deacetylation. In CM Hey-repression is counteracted by cardiac activators, which recruit histone acetylases and prevent Hey mediated deacetylation and subsequent repression for a subset of genes. Copyright © 2014 Elsevier Ltd. All rights reserved.

Structure and Function of Cardiac Troponin C (TNNC1): Implications for Heart Failure, Cardiomyopathies, and Troponin Modulating Drugs

PubMed Central

Li, Monica X.; Hwang, Peter M.

2015-01-01

In striated muscle, the protein troponin complex turns contraction on and off in a calcium-dependent manner. The calcium-sensing component of the complex is troponin C, which is expressed from the TNNC1 gene in both cardiac muscle and slow-twitch skeletal muscle (identical transcript in both tissues) and the TNNC2 gene in fast-twitch skeletal muscle. Cardiac troponin C (cTnC) is made up of two globular EF-hand domains connected by a flexible linker. The structural C-domain (cCTnC) contains two high affinity calcium-binding sites that are always occupied by Ca2+ or Mg2+ under physiologic conditions, stabilizing an open conformation that remains anchored to the rest of the troponin complex. In contrast, the regulatory N-domain (cNTnC) contains a single low affinity site that is largely unoccupied at resting calcium concentrations. During muscle activation, calcium binding to cNTnC favors an open conformation that binds to the switch region of troponin I, removing adjacent inhibitory regions of troponin I from actin and allowing muscle contraction to proceed. Regulation of the calcium binding affinity of cNTnC is physiologically important, because it directly impacts the calcium sensitivity of muscle contraction. Calcium sensitivity can be modified by drugs that stabilize the open form of cNTnC, post-translational modifications like phosphorylation of troponin I, or downstream thin filament protein interactions that impact the availability of the troponin I switch region. Recently, mutations in cTnC have been associated with hypertrophic or dilated cardiomyopathy. A detailed understanding of how calcium sensitivity is regulated through the troponin complex is necessary for explaining how mutations perturb its function to promote cardiomyopathy and how post-translational modifications in the thin filament affect heart function and heart failure. Troponin modulating drugs are being developed for the treatment of cardiomyopathies and heart failure. PMID:26232335

Genome-wide computational analysis reveals cardiomyocyte-specific transcriptional Cis-regulatory motifs that enable efficient cardiac gene therapy.

PubMed

Rincon, Melvin Y; Sarcar, Shilpita; Danso-Abeam, Dina; Keyaerts, Marleen; Matrai, Janka; Samara-Kuko, Ermira; Acosta-Sanchez, Abel; Athanasopoulos, Takis; Dickson, George; Lahoutte, Tony; De Bleser, Pieter; VandenDriessche, Thierry; Chuah, Marinee K

2015-01-01

Gene therapy is a promising emerging therapeutic modality for the treatment of cardiovascular diseases and hereditary diseases that afflict the heart. Hence, there is a need to develop robust cardiac-specific expression modules that allow for stable expression of the gene of interest in cardiomyocytes. We therefore explored a new approach based on a genome-wide bioinformatics strategy that revealed novel cardiac-specific cis-acting regulatory modules (CS-CRMs). These transcriptional modules contained evolutionary-conserved clusters of putative transcription factor binding sites that correspond to a "molecular signature" associated with robust gene expression in the heart. We then validated these CS-CRMs in vivo using an adeno-associated viral vector serotype 9 that drives a reporter gene from a quintessential cardiac-specific α-myosin heavy chain promoter. Most de novo designed CS-CRMs resulted in a >10-fold increase in cardiac gene expression. The most robust CRMs enhanced cardiac-specific transcription 70- to 100-fold. Expression was sustained and restricted to cardiomyocytes. We then combined the most potent CS-CRM4 with a synthetic heart and muscle-specific promoter (SPc5-12) and obtained a significant 20-fold increase in cardiac gene expression compared to the cytomegalovirus promoter. This study underscores the potential of rational vector design to improve the robustness of cardiac gene therapy.

An explicitly solvated full atomistic model of the cardiac thin filament and application on the calcium binding affinity effects from familial hypertrophic cardiomyopathy linked mutations

NASA Astrophysics Data System (ADS)

Williams, Michael; Schwartz, Steven

2015-03-01

The previous version of our cardiac thin filament (CTF) model consisted of the troponin complex (cTn), two coiled-coil dimers of tropomyosin (Tm), and 29 actin units. We now present the newest revision of the model to include explicit solvation. The model was developed to continue our study of genetic mutations in the CTF proteins which are linked to familial hypertrophic cardiomyopathies. Binding of calcium to the cTnC subunit causes subtle conformational changes to propagate through the cTnC to the cTnI subunit which then detaches from actin. Conformational changes propagate through to the cTnT subunit, which allows Tm to move into the open position along actin, leading to muscle contraction. Calcium disassociation allows for the reverse to occur, which results in muscle relaxation. The inclusion of explicit TIP3 water solvation allows for the model to get better individual local solvent to protein interactions; which are important when observing the N-lobe calcium binding pocket of the cTnC. We are able to compare in silica and in vitro experimental results to better understand the physiological effects from mutants, such as the R92L/W and F110V/I of the cTnT, on the calcium binding affinity compared to the wild type.

Clinical role of protein binding of quinolones.

PubMed

Bergogne-Bérézin, Eugénie

2002-01-01

Protein binding of antibacterials in plasma and tissues has long been considered a component of their pharmacokinetic parameters, playing a potential role in distribution, excretion and therapeutic effectiveness. Since the beginning of the 'antibacterial era', this factor has been extensively analysed for all antibacterial classes, showing that wide variations of the degree of protein binding occur even in the same antibacterial class, as with beta-lactams. As the understanding of protein binding grew, the complexity of the binding system was increasingly perceived and its dynamic character described. Studies of protein binding of the fluoroquinolones have shown that the great majority of these drugs exhibit low protein binding, ranging from approximately 20 to 40% in plasma, and that they are bound predominantly to albumin. The potential role in pharmacokinetics-pharmacodynamics of binding of fluoroquinolones to plasma, tissue and intracellular proteins has been analysed, but it has not been established that protein binding has any significant direct or indirect impact on therapeutic effectiveness. Regarding the factors influencing the tissue distribution of antibacterials, physicochemical characteristics and the small molecular size of fluoroquinolones permit a rapid penetration into extravascular sites and intracellularly, with a rapid equilibrium being established between intravascular and extravascular compartments. The high concentrations of these drugs achieved in tissues, body fluids and intracellularly, in addition to their wide antibacterial spectrum, mean that fluoroquinolones have therapeutic effectiveness in a large variety of infections. The tolerability of quinolones has generally been reported as good, based upon long experience in using pefloxacin, ciprofloxacin and ofloxacin in clinical practice. Among more recently developed molecules, good tolerability has been reported for levofloxacin, moxifloxacin and gatifloxacin, but certain other new compounds have been removed from the market because of renal, hepatic and cardiac toxicity. To what extent the protein binding of fluoroquinolones can play a role in their tolerability is unclear. In terms of drug-drug interactions, the role of protein binding is questionable: several drug combinations can be responsible for toxicity, such as with beta-lactams, metronidazole, theophylline, nonsteroidal anti-inflammatory agents or a series of drugs used for cardiac diseases, but protein binding does not seem to be involved in these interactions. In conclusion, protein binding of fluoroquinolones appears to be a complex phenomenon, but has no clear role in therapeutic effectiveness or toxicity.

The GIRK1 subunit potentiates G protein activation of cardiac GIRK1/4 hetero-tetramers

PubMed Central

Touhara, Kouki K; Wang, Weiwei; MacKinnon, Roderick

2016-01-01

G protein gated inward rectifier potassium (GIRK) channels are gated by direct binding of G protein beta-gamma subunits (Gβγ), signaling lipids, and intracellular Na+. In cardiac pacemaker cells, hetero-tetramer GIRK1/4 channels and homo-tetramer GIRK4 channels play a central role in parasympathetic slowing of heart rate. It is known that the Na+ binding site of the GIRK1 subunit is defective, but the functional difference between GIRK1/4 hetero-tetramers and GIRK4 homo-tetramers remains unclear. Here, using purified proteins and the lipid bilayer system, we characterize Gβγ and Na+ regulation of GIRK1/4 hetero-tetramers and GIRK4 homo-tetramers. We find in GIRK4 homo-tetramers that Na+ binding increases Gβγ affinity and thereby increases the GIRK4 responsiveness to G protein stimulation. GIRK1/4 hetero-tetramers are not activated by Na+, but rather are in a permanent state of high responsiveness to Gβγ, suggesting that the GIRK1 subunit functions like a GIRK4 subunit with Na+ permanently bound. DOI: http://dx.doi.org/10.7554/eLife.15750.001 PMID:27074664

Hellebrin and its aglycone form hellebrigenin display similar in vitro growth inhibitory effects in cancer cells and binding profiles to the alpha subunits of the Na+/K+-ATPase

PubMed Central

2013-01-01

Background Surface-expressed Na+/K+-ATPase (NaK) has been suggested to function as a non-canonical cardiotonic steroid-binding receptor that activates multiple signaling cascades, especially in cancer cells. By contrast, the current study establishes a clear correlation between the IC50in vitro growth inhibitory concentration in human cancer cells and the Ki for the inhibition of activity of purified human α1β1 NaK. Methods The in vitro growth inhibitory effects of seven cardiac glycosides including five cardenolides (ouabain, digoxin, digitoxin, gitoxin, uzarigenin-rhamnoside, and their respective aglycone forms) and two bufadienolides (gamabufotalin-rhamnoside and hellebrin, and their respective aglycone forms) were determined by means of the MTT colorimetric assay and hellebrigenin-induced cytotoxic effects were visualized by means of quantitative videomicroscopy. The binding affinity of ten of the 14 compounds under study was determined with respect to human α1β1, α2β1 and α3β1 NaK complexes. Lactate releases and oxygen consumption rates were also determined in cancer cells treated with these various cardiac glycosides. Results Although cardiotonic steroid aglycones usually display weaker binding affinity and in vitro anticancer activity than the corresponding glycoside, the current study demonstrates that the hellebrin / hellebrigenin pair is at odds with respect to this rule. In addition, while some cardiac steroid glycosides (e.g., digoxin), but not the aglycones, display a higher binding affinity for the α2β1 and α3β1 than for the α1β1 complex, both hellebrin and its aglycone hellebrigenin display ~2-fold higher binding affinity for α1β1 than for the α2β1 and α3β1 complexes. Finally, the current study highlights a common feature for all cardiotonic steroids analyzed here, namely a dramatic reduction in the oxygen consumption rate in cardenolide- and bufadienolide-treated cells, reflecting a direct impact on mitochondrial oxidative phosphorylation. Conclusions Altogether, these data show that the binding affinity of the bufadienolides and cardenolides under study is usually higher for the α2β1 and α3β1 than for the α1β1 NaK complex, excepted for hellebrin and its aglycone form, hellebrigenin, with hellebrigenin being as potent as hellebrin in inhibiting in vitro cancer cell growth. PMID:23621895

Downregulation of S100A4 Alleviates Cardiac Fibrosis via Wnt/β -Catenin Pathway in Mice.

PubMed

Qian, LiJun; Hong, Jian; Zhang, YanMei; Zhu, MengLin; Wang, XinChun; Zhang, YanJuan; Chu, Ming; Yao, Jing; Xu, Di

2018-05-07

Cardiac fibrosis is a pathological change leading to cardiac remodeling during the progression of myocardial ischemic diseases, and its therapeutic strategy remains to be explored. S100A4, a calcium-binding protein, participates in fibrotic diseases with an unclear mechanism. This study aimed to investigate the role of S100A4 in cardiac fibrosis. Cardiac fibroblasts from neonatal C57BL/6 mouse hearts were isolated and cultured. Myocardial infarction was induced by ligating the left anterior descending coronary artery (LAD). The ligation was not performed in the sham group. A volume of 5×105pfu/g adenovirus or 5 µM/g ICG-001 was intramyocardially injected into five parts bordering the infarction zone or normal region. We used Western blotting, quantitative RT-PCR, immunofluorescence, immunohistochemistry and Masson's trichrome staining to explore the function of S100A4. We found significant increases of S100A4 level and cardiac fibrosis markers, and β-catenin signaling activation in vitro and in vivo. In addition, knockdown of S100A4 significantly reduced cardiac fibrosis and β-catenin levels. Moreover, the expression of S100A4 decreased after ICG-001 inhibited β-catenin signal pathway. Downregulation of S100A4 alleviates cardiac fibrosis via Wnt/β -catenin pathway in mice. S100A4 may be a therapeutic target of cardiac fibrosis. © 2018 The Author(s). Published by S. Karger AG, Basel.

Silicon central pattern generators for cardiac diseases

PubMed Central

Nogaret, Alain; O'Callaghan, Erin L; Lataro, Renata M; Salgado, Helio C; Meliza, C Daniel; Duncan, Edward; Abarbanel, Henry D I; Paton, Julian F R

2015-01-01

Cardiac rhythm management devices provide therapies for both arrhythmias and resynchronisation but not heart failure, which affects millions of patients worldwide. This paper reviews recent advances in biophysics and mathematical engineering that provide a novel technological platform for addressing heart disease and enabling beat-to-beat adaptation of cardiac pacing in response to physiological feedback. The technology consists of silicon hardware central pattern generators (hCPGs) that may be trained to emulate accurately the dynamical response of biological central pattern generators (bCPGs). We discuss the limitations of present CPGs and appraise the advantages of analog over digital circuits for application in bioelectronic medicine. To test the system, we have focused on the cardio-respiratory oscillators in the medulla oblongata that modulate heart rate in phase with respiration to induce respiratory sinus arrhythmia (RSA). We describe here a novel, scalable hCPG comprising physiologically realistic (Hodgkin–Huxley type) neurones and synapses. Our hCPG comprises two neurones that antagonise each other to provide rhythmic motor drive to the vagus nerve to slow the heart. We show how recent advances in modelling allow the motor output to adapt to physiological feedback such as respiration. In rats, we report on the restoration of RSA using an hCPG that receives diaphragmatic electromyography input and use it to stimulate the vagus nerve at specific time points of the respiratory cycle to slow the heart rate. We have validated the adaptation of stimulation to alterations in respiratory rate. We demonstrate that the hCPG is tuneable in terms of the depth and timing of the RSA relative to respiratory phase. These pioneering studies will now permit an analysis of the physiological role of RSA as well as its any potential therapeutic use in cardiac disease. PMID:25433077

Magnetic Resonance Characterization of Cardiac Adaptation and Myocardial Fibrosis in Pulmonary Hypertension Secondary to Systemic-To-Pulmonary Shunt.

PubMed

Pereda, Daniel; García-Lunar, Inés; Sierra, Federico; Sánchez-Quintana, Damián; Santiago, Evelyn; Ballesteros, Constanza; Encalada, Juan F; Sánchez-González, Javier; Fuster, Valentín; Ibáñez, Borja; García-Álvarez, Ana

2016-09-01

Pulmonary hypertension (PH) and right ventricular (RV) dysfunction are strong predictors of morbidity and mortality among patients with congenital heart disease. Early detection of RV involvement may be useful in the management of these patients. We aimed to assess progressive cardiac adaptation and quantify myocardial extracellular volume in an experimental porcine model of PH because of aorto-pulmonary shunt using cardiac magnetic resonance (CMR). To characterize serial cardiac adaptation, 12 pigs (aorto-pulmonary shunt [n=6] or sham operation [n=6]) were evaluated monthly with right heart catheterization, CMR, and computed tomography during 4 months, followed by pathology analysis. Extracellular volume by CMR in different myocardial regions was studied in 20 animals (aorto-pulmonary shunt [n=10] or sham operation [n=10]) 3 months after the intervention. All shunted animals developed PH. CMR evidenced progressive RV hypertrophy and dysfunction secondary to increased afterload and left ventricular dilatation secondary to volume overload. Shunt flow by CMR strongly correlated with PH severity, left ventricular end-diastolic pressure, and left ventricular dilatation. T1-mapping sequences demonstrated increased extracellular volume at the RV insertion points, the interventricular septum, and the left ventricular lateral wall, reproducing the pattern of fibrosis found on pathology. Extracellular volume at the RV insertion points strongly correlated with pulmonary hemodynamics and RV dysfunction. Prolonged systemic-to-pulmonary shunting in growing piglets induces PH with biventricular remodeling and myocardial fibrosis that can be detected and monitored using CMR. These results may be useful for the diagnosis and management of congenital heart disease patients with pulmonary overcirculation. © 2016 American Heart Association, Inc.

[Adaptation to effort in patients with chronic cardiac insufficiency; study by post-exercise Doppler echocardiography, comparative results with a control population].

PubMed

Pouillart, F; Perchet, H; Duval-Moulin, A M; Heintz, J F; Hittinger, L; Brun, P; Castaigne, A; Dubois-Randé, J L

1995-04-01

Adaptation to exercise was studied by post-exercise Doppler echocardiography in patients with chronic cardiac failure and an apparently healthy control population matched for age. This post-exercise Doppler echocardiographic method initially introduced for the detection of myocardial ischaemia has already been validated in normal subjects for the analysis of haemodynamic changes caused by exercise providing the data is recorded in the first 5 minutes following recovery in the recumbent position. Eleven patients with chronic cardiac failure in NYHA classes II or III with a mean age of 54 +/- 11 years and 6 controls (mean age: 46 +/- 9 years) were investigated. The patients had been stabilised for at least 3 months with a vasodilator and diuretic therapy: the control subjects had no medication. After bicycle ergometry performed to 70% of maximum capacity, the subjects were positioned in the left lateral recumbent position. Doppler echocardiography was then performed in the immediate recovery phase. When compared to the control population, the patients with cardiac failure had a reduced chronotropic reserve, a smaller increase in the parameters of myocardial contractility (maximal aortic velocity, maximal aortic acceleration and left ventricular fractional shortening) without an increase in left ventricular end diastolic dimensions in subjects with severe dilatation under basal conditions (left ventricular end diastolic dimension 69 +/- 3 mm). This result suggests the absence of a Frank-Starling effect. The lack of adaptation of the peripheral vascular system was demonstrated by the lack of reduction of left ventricular end systolic stress, already greatly increased at rest (176 vs 77 +/- 10 g/cm2 for patients, compared with controls; p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Elabela/Toddler Is an Endogenous Agonist of the Apelin APJ Receptor in the Adult Cardiovascular System, and Exogenous Administration of the Peptide Compensates for the Downregulation of Its Expression in Pulmonary Arterial Hypertension

PubMed Central

Yang, Peiran; Read, Cai; Kuc, Rhoda E.; Buonincontri, Guido; Southwood, Mark; Torella, Rubben; Upton, Paul D.; Crosby, Alexi; Sawiak, Stephen J.; Carpenter, T. Adrian; Glen, Robert C.; Morrell, Nicholas W.; Maguire, Janet J.

2017-01-01

Background: Elabela/toddler (ELA) is a critical cardiac developmental peptide that acts through the G-protein–coupled apelin receptor, despite lack of sequence similarity to the established ligand apelin. Our aim was to investigate the receptor pharmacology, expression pattern, and in vivo function of ELA peptides in the adult cardiovascular system, to seek evidence for alteration in pulmonary arterial hypertension (PAH) in which apelin signaling is downregulated, and to demonstrate attenuation of PAH severity with exogenous administration of ELA in a rat model. Methods: In silico docking analysis, competition binding experiments, and downstream assays were used to characterize ELA receptor binding in human heart and signaling in cells expressing the apelin receptor. ELA expression in human cardiovascular tissues and plasma was determined using real-time quantitative polymerase chain reaction, dual-labeling immunofluorescent staining, and immunoassays. Acute cardiac effects of ELA-32 and [Pyr1]apelin-13 were assessed by MRI and cardiac catheterization in anesthetized rats. Cardiopulmonary human and rat tissues from PAH patients and monocrotaline- and Sugen/hypoxia-exposed rats were used to show changes in ELA expression in PAH. The effect of ELA treatment on cardiopulmonary remodeling in PAH was investigated in the monocrotaline rat model. Results: ELA competed for binding of apelin in human heart with overlap for the 2 peptides indicated by in silico modeling. ELA activated G-protein– and β-arrestin–dependent pathways. We detected ELA expression in human vascular endothelium and plasma. Comparable to apelin, ELA increased cardiac contractility, ejection fraction, and cardiac output and elicited vasodilatation in rat in vivo. ELA expression was reduced in cardiopulmonary tissues from PAH patients and PAH rat models, respectively. ELA treatment significantly attenuated elevation of right ventricular systolic pressure and right ventricular hypertrophy and pulmonary vascular remodeling in monocrotaline-exposed rats. Conclusions: These results show that ELA is an endogenous agonist of the human apelin receptor, exhibits a cardiovascular profile comparable to apelin, and is downregulated in human disease and rodent PAH models, and exogenous peptide can reduce the severity of cardiopulmonary remodeling and function in PAH in rats. This study provides additional proof of principle that an apelin receptor agonist may be of therapeutic use in PAH in humans. PMID:28137936

Elabela/Toddler Is an Endogenous Agonist of the Apelin APJ Receptor in the Adult Cardiovascular System, and Exogenous Administration of the Peptide Compensates for the Downregulation of Its Expression in Pulmonary Arterial Hypertension.

PubMed

Yang, Peiran; Read, Cai; Kuc, Rhoda E; Buonincontri, Guido; Southwood, Mark; Torella, Rubben; Upton, Paul D; Crosby, Alexi; Sawiak, Stephen J; Carpenter, T Adrian; Glen, Robert C; Morrell, Nicholas W; Maguire, Janet J; Davenport, Anthony P

2017-03-21

Elabela/toddler (ELA) is a critical cardiac developmental peptide that acts through the G-protein-coupled apelin receptor, despite lack of sequence similarity to the established ligand apelin. Our aim was to investigate the receptor pharmacology, expression pattern, and in vivo function of ELA peptides in the adult cardiovascular system, to seek evidence for alteration in pulmonary arterial hypertension (PAH) in which apelin signaling is downregulated, and to demonstrate attenuation of PAH severity with exogenous administration of ELA in a rat model. In silico docking analysis, competition binding experiments, and downstream assays were used to characterize ELA receptor binding in human heart and signaling in cells expressing the apelin receptor. ELA expression in human cardiovascular tissues and plasma was determined using real-time quantitative polymerase chain reaction, dual-labeling immunofluorescent staining, and immunoassays. Acute cardiac effects of ELA-32 and [Pyr 1 ]apelin-13 were assessed by MRI and cardiac catheterization in anesthetized rats. Cardiopulmonary human and rat tissues from PAH patients and monocrotaline- and Sugen/hypoxia-exposed rats were used to show changes in ELA expression in PAH. The effect of ELA treatment on cardiopulmonary remodeling in PAH was investigated in the monocrotaline rat model. ELA competed for binding of apelin in human heart with overlap for the 2 peptides indicated by in silico modeling. ELA activated G-protein- and β-arrestin-dependent pathways. We detected ELA expression in human vascular endothelium and plasma. Comparable to apelin, ELA increased cardiac contractility, ejection fraction, and cardiac output and elicited vasodilatation in rat in vivo. ELA expression was reduced in cardiopulmonary tissues from PAH patients and PAH rat models, respectively. ELA treatment significantly attenuated elevation of right ventricular systolic pressure and right ventricular hypertrophy and pulmonary vascular remodeling in monocrotaline-exposed rats. These results show that ELA is an endogenous agonist of the human apelin receptor, exhibits a cardiovascular profile comparable to apelin, and is downregulated in human disease and rodent PAH models, and exogenous peptide can reduce the severity of cardiopulmonary remodeling and function in PAH in rats. This study provides additional proof of principle that an apelin receptor agonist may be of therapeutic use in PAH in humans. © 2017 The Authors.

Proteomic analysis of the protective effects of aqueous bark extract of Terminalia arjuna (Roxb.) on isoproterenol-induced cardiac hypertrophy in rats.

PubMed

Kumar, Santosh; Jahangir Alam, Md; Prabhakar, Pankaj; Ahmad, Sayeed; Maulik, Subir K; Sharma, Manish; Goswami, Shyamal K

2017-02-23

Aqueous bark extract of Terminalia arjuna (TA) has been in use as an ethnomedicine for cardiovascular ailments in the Indian subcontinent for centuries. Studies using hemodynamic, ROS scavenging and anti-inflammatory parameters in animal models have shown its anti-atherogenic, hypotensive, inotropic, anti-inflammatory effects. However, details analysis on its effects on established molecular and cell biological markers are a prerequisite for its wider acceptance to the medical community. To test the efficacy of TA extract in ameliorating cardiac hypertrophy induced by ISO in rats. Cardiac hypertrophy was induced by ISO (5mg/kg/day s.c. for 14 days) in rats and a standardized aqueous extract of TA stem bark was orally administered by gavage. Total RNA and protein were isolated from control, ISO, ISO plus TA and TA treated rat hearts and analyzed for the transcripts for the markers of hypertrophy, signaling kinases, transcription factors and total protein profile. TA extract reversed the induction of fetal genes like β-myosin heavy chain, skeletal α-actin and brain natriuretic peptide in hypertrophic rat hearts. While ISO slightly increased the level of phospho-ERK, TA repressed it to about one third of the base line level. Survival kinase Akt, ER stress marker Grp78 and epigenetic regulator HDAC5 were augmented by ISO and TA restored them by various extents. ISO administration moderately increased the transcription factor NFκB binding activity, while coadministration of TA further increased it. AP-1 binding activity was largely unchanged by ISO treatment but it was upregulated when administered along with TA. MEF2D binding activity was increased by ISO and TA restored it to the baseline level. Global proteomic analysis revealed that TA treatment restored a subset of proteins up- and down-regulated in the hypertrophied hearts. Amongst those restored by TA were purinergic receptor X, myosin light chain 3, tropomyosin, and kininogen; suggesting a nodal role of TA in modulating cardiac function. This study for the first time reveals that TA partially or completely restores the marker mRNAs, signaling kinases, transcription factors and total protein profile in rat heart, thereby demonstrating its efficacy in preventing ISO-induced cardiac hypertrophy. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

Tryptase activates isolated adult cardiac fibroblasts via protease activated receptor-2 (PAR-2).

PubMed

Murray, David B; McLarty-Williams, Jennifer; Nagalla, Krishna T; Janicki, Joseph S

2012-03-01

Protease activated receptor-2 (PAR-2) derived cycloxygenase-2 (COX-2) was recently implicated in a cardiac mast cell and fibroblast cross-talk signaling cascade mediating myocardial remodeling secondary to mechanical stress. We designed this study to investigate in vitro assays of isolated adult cardiac fibroblasts to determine whether binding of tryptase to the PAR-2 receptor on cardiac fibroblasts will lead to increased expression of COX-2 and subsequent formation of the arachodonic acid metabolite 15-d-Prostaglandin J(2) (15-d-PGJ(2)). The effects of tryptase (100 mU) and co-incubation with PAR-2 inhibitor peptide sequence FSLLRY-NH(2) (10(-6)M) on proliferation, hydroxyproline concentration, 15-d-PGJ(2) formation and PAR-2/COX-2 expression were investigated in fibroblasts isolated from 9 week old SD rats. Tryptase induced a significant increase in fibroproliferation, hydroxyproline, 15-d-PGJ(2) formation and PAR-2 expression which were markedly attenuated by FSLLRY. Tryptase-induced changes in cardiac fibroblast function utilize a PAR-2 dependent mechanism.

An ECG signals compression method and its validation using NNs.

PubMed

Fira, Catalina Monica; Goras, Liviu

2008-04-01

This paper presents a new algorithm for electrocardiogram (ECG) signal compression based on local extreme extraction, adaptive hysteretic filtering and Lempel-Ziv-Welch (LZW) coding. The algorithm has been verified using eight of the most frequent normal and pathological types of cardiac beats and an multi-layer perceptron (MLP) neural network trained with original cardiac patterns and tested with reconstructed ones. Aspects regarding the possibility of using the principal component analysis (PCA) to cardiac pattern classification have been investigated as well. A new compression measure called "quality score," which takes into account both the reconstruction errors and the compression ratio, is proposed.

A gain-of-function mutation in the M-domain of cardiac myosin-binding protein-C increases binding to actin.

PubMed

Bezold, Kristina L; Shaffer, Justin F; Khosa, Jaskiran K; Hoye, Elaine R; Harris, Samantha P

2013-07-26

The M-domain is the major regulatory subunit of cardiac myosin-binding protein-C (cMyBP-C) that modulates actin and myosin interactions to influence muscle contraction. However, the precise mechanism(s) and the specific residues involved in mediating the functional effects of the M-domain are not fully understood. Positively charged residues adjacent to phosphorylation sites in the M-domain are thought to be critical for effects of cMyBP-C on cross-bridge interactions by mediating electrostatic binding with myosin S2 and/or actin. However, recent structural studies revealed that highly conserved sequences downstream of the phosphorylation sites form a compact tri-helix bundle. Here we used site-directed mutagenesis to probe the functional significance of charged residues adjacent to the phosphorylation sites and conserved residues within the tri-helix bundle. Results confirm that charged residues adjacent to phosphorylation sites and residues within the tri-helix bundle are important for mediating effects of the M-domain on contraction. In addition, four missense variants within the tri-helix bundle that are associated with human hypertrophic cardiomyopathy caused either loss-of-function or gain-of-function effects on force. Importantly, the effects of the gain-of-function variant, L348P, increased the affinity of the M-domain for actin. Together, results demonstrate that functional effects of the M-domain are not due solely to interactions with charged residues near phosphorylatable serines and provide the first demonstration that the tri-helix bundle contributes to the functional effects of the M-domain, most likely by binding to actin.

Microtubule Stabilization in Pressure Overload Cardiac Hypertrophy

PubMed Central

Sato, Hiroshi; Nagai, Toshio; Kuppuswamy, Dhandapani; Narishige, Takahiro; Koide, Masaaki; Menick, Donald R.; IV, George Cooper

1997-01-01

Increased microtubule density, for which microtubule stabilization is one potential mechanism, causes contractile dysfunction in cardiac hypertrophy. After microtubule assembly, α-tubulin undergoes two, likely sequential, time-dependent posttranslational changes: reversible carboxy-terminal detyrosination (Tyr-tubulin ↔ Glu-tubulin) and then irreversible deglutamination (Glu-tubulin → Δ2-tubulin), such that Glu- and Δ2-tubulin are markers for long-lived, stable microtubules. Therefore, we generated antibodies for Tyr-, Glu-, and Δ2-tubulin and used them for staining of right and left ventricular cardiocytes from control cats and cats with right ventricular hypertrophy. Tyr- tubulin microtubule staining was equal in right and left ventricular cardiocytes of control cats, but Glu-tubulin and Δ2-tubulin staining were insignificant, i.e., the microtubules were labile. However, Glu- and Δ2-tubulin were conspicuous in microtubules of right ventricular cardiocytes from pressure overloaded cats, i.e., the microtubules were stable. This finding was confirmed in terms of increased microtubule drug and cold stability in the hypertrophied cells. In further studies, we found an increase in a microtubule binding protein, microtubule-associated protein 4, on both mRNA and protein levels in pressure-hypertrophied myocardium. Thus, microtubule stabilization, likely facilitated by binding of a microtubule-associated protein, may be a mechanism for the increased microtubule density characteristic of pressure overload cardiac hypertrophy. PMID:9362514

Functional Outcome Trajectories After Out-of-Hospital Pediatric Cardiac Arrest.

PubMed

Silverstein, Faye S; Slomine, Beth S; Christensen, James; Holubkov, Richard; Page, Kent; Dean, J Michael; Moler, Frank W

2016-12-01

To analyze functional performance measures collected prospectively during the conduct of a clinical trial that enrolled children (up to age 18 yr old), resuscitated after out-of-hospital cardiac arrest, who were at high risk of poor outcomes. Children with Glasgow Motor Scale score less than 5, within 6 hours of resuscitation, were enrolled in a clinical trial that compared two targeted temperature management interventions (THAPCA-OH, NCT00878644). The primary outcome, 12-month survival with Vineland Adaptive Behavior Scale, second edition, score greater or equal to 70, did not differ between groups. Thirty-eight North American PICUs. Two hundred ninety-five children were enrolled; 270 of 295 had baseline Vineland Adaptive Behavior Scale, second edition, scores greater or equal to 70; 87 of 270 survived 1 year. Targeted temperatures were 33.0°C and 36.8°C for hypothermia and normothermia groups. Baseline measures included Vineland Adaptive Behavior Scale, second edition, Pediatric Cerebral Performance Category, and Pediatric Overall Performance Category. Pediatric Cerebral Performance Category and Pediatric Overall Performance Category were rescored at hospital discharges; all three were scored at 3 and 12 months. In survivors with baseline Vineland Adaptive Behavior Scale, second edition scores greater or equal to 70, we evaluated relationships of hospital discharge Pediatric Cerebral Performance Category with 3- and 12-month scores and between 3- and 12-month Vineland Adaptive Behavior Scale, second edition, scores. Hospital discharge Pediatric Cerebral Performance Category scores strongly predicted 3- and 12-month Pediatric Cerebral Performance Category (r = 0.82 and 0.79; p < 0.0001) and Vineland Adaptive Behavior Scale, second edition, scores (r = -0.81 and -0.77; p < 0.0001). Three-month Vineland Adaptive Behavior Scale, second edition, scores strongly predicted 12-month performance (r = 0.95; p < 0.0001). Hypothermia treatment did not alter these relationships. In comatose children, with Glasgow Motor Scale score less than 5 in the initial hours after out-of-hospital cardiac arrest resuscitation, function scores at hospital discharge and at 3 months predicted 12-month performance well in the majority of survivors.

Nanotized PPARα Overexpression Targeted to Hypertrophied Myocardium Improves Cardiac Function by Attenuating the p53-GSK3β-Mediated Mitochondrial Death Pathway.

PubMed

Rana, Santanu; Datta, Ritwik; Chaudhuri, Ratul Datta; Chatterjee, Emeli; Chawla-Sarkar, Mamta; Sarkar, Sagartirtha

2018-05-09

Metabolic remodeling of cardiac muscles during pathological hypertrophy is characterized by downregulation of fatty acid oxidation (FAO) regulator, peroxisome proliferator-activated receptor alpha (PPARα). Thereby, we hypothesized that a cardiac-specific induction of PPARα might restore the FAO-related protein expression and resultant energy deficit. In the present study, consequences of PPARα augmentation were evaluated for amelioration of chronic oxidative stress, myocyte apoptosis, and cardiac function during pathological cardiac hypertrophy. Nanotized PPARα overexpression targeted to myocardium was done by a stearic acid-modified carboxymethyl-chitosan (CMC) conjugated to a 20-mer myocyte-targeted peptide (CMCP). Overexpression of PPARα ameliorated pathological hypertrophy and improved cardiac function. Augmented PPARα in hypertrophied myocytes revealed downregulated p53 acetylation (lys 382), leading to reduced apoptosis. Such cells showed increased binding of PPARα with p53 that in turn reduced interaction of p53 with glycogen synthase kinase-3β (GSK3β), which upregulated inactive phospho-GSK3β (serine [Ser]9) expression within mitochondrial protein fraction. Altogether, the altered molecular milieu in PPARα-overexpressed hypertrophy groups restored mitochondrial structure and function both in vitro and in vivo. Cardiomyocyte-targeted overexpression of a protein of interest (PPARα) by nanotized plasmid has been described for the first time in this study. Our data provide a novel insight towards regression of pathological hypertrophy by ameliorating mitochondrial oxidative stress in targeted PPARα-overexpressed myocardium. PPARα-overexpression during pathological hypertrophy showed substantial betterment of mitochondrial structure and function, along with downregulated apoptosis. Myocardium-targeted overexpression of PPARα during pathological cardiac hypertrophy led to an overall improvement of cardiac energy deficit and subsequent cardiac function, thereby, opening up a potential avenue for cardiac tissue engineering during hypertrophic cardiac pathophysiology.

Impact of disease-causing mutations on inter-domain interactions in cMyBP-C: a steered molecular dynamics study.

PubMed

Krishnamoorthy, Navaneethakrishnan; Gajendrarao, Poornima; Olivotto, Iacopo; Yacoub, Magdi

2017-07-01

The molecular interactions of the sarcomeric proteins are essential in the regulation of various cardiac functions. Mutations in the gene MYBPC3 coding for cardiac myosin-binding protein-C (cMyBP-C), a multi-domain protein, are the most common cause of hypertrophic cardiomyopathy (HCM). The N-terminal complex, C1-motif-C2 is a central region in cMyBP-C for the regulation of cardiac muscle contraction. However, the mechanism of binding/unbinding of this complex during health and disease is unknown. Here, we study possible mechanisms of unbinding using steered molecular dynamics simulations for the complex in the wild type, in single mutations (E258K in C1, E441K in C2), as well as in a double mutation (E258K in C1 + E441K in C2), which are associated with severe HCM. The observed molecular events and the calculation of force utilized for the unbinding suggest the following: (i) double mutation can encourage the formation of rigid complex that required large amount of force and long-time to unbind, (ii) C1 appears to start to unbind ahead of C2 regardless of the mutation, and (iii) unbinding of C2 requires larger amount of force than C1. This molecular insight suggests that key HCM-causing mutations might significantly modify the native affinity required for the assembly of the domains in cMyBP-C, which is essential for normal cardiac function.

Quantification of Cardiac Biomarkers using Label-free and Multiplexed Gold Nanorod Bioprobes for Myocardial Infarction Diagnosis

PubMed Central

Tang, Liang; Casas, Justin

2014-01-01

Gold nanorod (GNR) is an attractive optical transducer for label-free biosensing owing to the localized surface plasmon resonance (LSPR) which is highly sensitive to the dielectric constant of the surrounding medium modulated by biological bindings. By adjusting the nanorod aspect ratio (length to width ratio), desired absorption wavelength can be continuously tuned from 600 to 1,100 nm. Here we demonstrated a linear relationship between the aspect ratio and the LSPR peak wavelength. Taking advantage of this tunability feature, we developed a multiplexed GNR sensor by combining nanorods with distinct LSPR wavelengths. Specifically, GNRs of AR 2.1 and 4.2 exhibiting longitudinal plasmonic band of 640 and 830 nm respectively were functionalized with specific antibody. Concentrations of multiple analytes were measured by correlating to the spectral shift at the distinct plasmon band maxima upon specific binding. The practical use of this mixed bioprobes for simultaneous quantification of cardiac biomarkers (myoglobin and cardiac troponin I) in the clinically significant sensing range was described. The LSPR red shift magnitude is linearly proportional to the increase in the target analyte concentration (R2 = 0.98). The calibration curve can clearly differentiate varying biomarker amounts with a high specificity. For multiplexed biosensing, the plasmon shift at the dedicated peak wavelength can be specifically correlated with spiked biomarker for simultaneous detection in the sample mixture. This technology can be further transformed onto miniaturized biochips based on the nanosized optical transducer to allow point-of-care blood testing for risk stratifications of cardiac patients in clinical settings. PMID:24858675

Heart fatty acid binding protein (H-FABP) as a diagnostic biomarker in patients with acute coronary syndrome.

PubMed

Gururajan, Priya; Gurumurthy, Prema; Nayar, Pradeep; Srinivasa Nageswara Rao, G; Babu, Sai; Cherian, K M

2010-11-01

Diagnosis of myocardial ischaemia at an early stage in the emergency department is often difficult. A recently proposed biomarker, heart fatty acid binding protein (H-FABP) has been found to appear in the circulation superior to that of cardiac troponins in the early hours of acute coronary syndrome. We proposed to evaluate the levels of H-FABP and ascertain its utility as an early biomarker for acute coronary syndrome (ACS). The present study was carried out in 485 subjects, of whom 297 were diagnosed as patients with ACS, 89 were diagnosed as non-cardiac chest pain (NCCP) and 99 people served as healthy controls. H-FABP levels were measured in comparison with standard markers such as troponin I and CK-MB in all subjects enrolled in the study. The levels of H-FABP were significantly raised in patients when compared to controls and NCCP (P<0.001). Receiver Operator Characteristic Curve (ROC) analysis showed H-FABP to be a good discriminator between patients with ischaemic heart disease and patients without ischaemic heart disease. The area under the curve was found to be 0.965 with 95% CI (0.945-0.979). The cut-off value above which H-FABP can be considered positive was found to be 17.7ng/ml. H-FABP is a promising biomarker for the early detection of patients with acute coronary syndrome. Copyright © 2010 Australasian Society of Cardiac and Thoracic Surgeons and the Cardiac Society of Australia and New Zealand. Published by Elsevier B.V. All rights reserved.

High-throughput identification of off-targets for the mechanistic study of severe adverse drug reactions induced by analgesics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pan, Jian-Bo; Ji, Nan; Pan, Wen

2014-01-01

Drugs may induce adverse drug reactions (ADRs) when they unexpectedly bind to proteins other than their therapeutic targets. Identification of these undesired protein binding partners, called off-targets, can facilitate toxicity assessment in the early stages of drug development. In this study, a computational framework was introduced for the exploration of idiosyncratic mechanisms underlying analgesic-induced severe adverse drug reactions (SADRs). The putative analgesic-target interactions were predicted by performing reverse docking of analgesics or their active metabolites against human/mammal protein structures in a high-throughput manner. Subsequently, bioinformatics analyses were undertaken to identify ADR-associated proteins (ADRAPs) and pathways. Using the pathways and ADRAPsmore » that this analysis identified, the mechanisms of SADRs such as cardiac disorders were explored. For instance, 53 putative ADRAPs and 24 pathways were linked with cardiac disorders, of which 10 ADRAPs were confirmed by previous experiments. Moreover, it was inferred that pathways such as base excision repair, glycolysis/glyconeogenesis, ErbB signaling, calcium signaling, and phosphatidyl inositol signaling likely play pivotal roles in drug-induced cardiac disorders. In conclusion, our framework offers an opportunity to globally understand SADRs at the molecular level, which has been difficult to realize through experiments. It also provides some valuable clues for drug repurposing. - Highlights: • A novel computational framework was developed for mechanistic study of SADRs. • Off-targets of drugs were identified in large scale and in a high-throughput manner. • SADRs like cardiac disorders were systematically explored in molecular networks. • A number of ADR-associated proteins were identified.« less

Role of Natural IgM Autoantibodies (IgM-NAA) and IgM Anti-Leukocyte Antibodies (IgM-ALA) in Regulating Inflammation.

PubMed

Lobo, Peter I

2017-01-01

Natural IgM autoantibodies (IgM-NAA) are rapidly produced to inhibit pathogens and abrogate inflammation mediated by invading microorganisms and host neoantigens. IgM-NAA achieve this difficult task by being polyreactive with low binding affinity but with high avidity, characteristics that allow these antibodies to bind antigenic determinants shared by pathogens and neoantigens. Hence the same clones of natural IgM can bind and mask host neoantigens as well as inhibit microorganisms. In addition, IgM-NAA regulate the inflammatory response via mechanisms involving binding of IgM to apoptotic cells to enhance their removal and binding of IgM to live leukocytes to regulate their function. Secondly, we review how natural IgM prevents autoimmune disorders arising from pathogenic IgG autoantibodies as well as by autoreactive B and T cells that have escaped tolerance mechanisms. Thirdly, using IgM knockout mice, we show that regulatory B and T cells require IgM to effectively regulate inflammation mediated by innate, adaptive and autoimmune mechanisms. It is therefore not surprising why the host positively selects such autoreactive B1 cells that generate protective IgM-NAA, which are also evolutionarily conserved. Fourthly, we show that IgM anti-leukocyte autoantibodies (IgM-ALA) levels and their repertoire can vary in normal humans and disease states and this variation may partly explain the observed differences in the inflammatory response after infection, ischemic injury or after a transplant. Finally we also show how protective IgM-NAA can be rendered pathogenic under non-physiological conditions. IgM-NAA have therapeutic potential. Polyclonal IgM infusions can be used to abrogate ongoing inflammation. Additionally, inflammation arising after ischemic kidney injury, e.g., during high-risk elective cardiac surgery or after allograft transplantation, can be prevented by pre-emptively infusing polyclonal IgM, or DC pretreated ex vivo with IgM, or by increasing in vivo IgM with a vaccine approach. Cell therapy with IgM pretreated cells, is appealing as less IgM will be required.

Beneficial Autophagic Activities, Mitochondrial Function, and Metabolic Phenotype Adaptations Promoted by High-Intensity Interval Training in a Rat Model

PubMed Central

Li, Fang-Hui; Li, Tao; Ai, Jing-Yi; Sun, Lei; Min, Zhu; Duan, Rui; Zhu, Ling; Liu, Yan-ying; Liu, Timon Cheng-Yi

2018-01-01

The effects of high-intensity interval (HIIT) and moderate-intensity continuous training (MICT) on basal autophagy and mitochondrial function in cardiac and skeletal muscle and plasma metabolic phenotypes have not been clearly characterized. Here, we investigated how 10-weeks HIIT and MICT differentially modify basal autophagy and mitochondrial markers in cardiac and skeletal muscle and conducted an untargeted metabolomics study with proton nuclear magnetic resonance (1H NMR) spectroscopy and multivariate statistical analysis of plasma metabolic phenotypes. Male Sprague–Dawley rats were separated into three groups: sedentary control (SED), MICT, and HIIT. Rats underwent evaluation of exercise performance, including exercise tolerance and grip strength, and blood lactate levels were measured immediately after an incremental exercise test. Plasma samples were analyzed by 1H NMR. The expression of autophagy and mitochondrial markers and autophagic flux (LC3II/LC3-I ratio) in cardiac, rectus femoris, and soleus muscle were analyzed by western blotting. Time to exhaustion and grip strength increased significantly following HIIT compared with that in both SED and MICT groups. Compared with those in the SED group, blood lactate level, and the expression of SDH, COX-IV, and SIRT3 significantly increased in rectus femoris and soleus muscle of both HIIT and MICT groups. Meanwhile, SDH and COX-IV content of cardiac muscle and COX-IV and SIRT3 content of rectus femoris and soleus muscle increased significantly following HIIT compared with that following MICT. The expression of LC3-II, ATG-3, and Beclin-1 and LC3II/LC3-I ratio were significantly increased only in soleus and cardiac muscle following HIIT. These data indicate that HIIT was more effective for improving physical performance and facilitating cardiac and skeletal muscle adaptations that increase mitochondrial function and basal autophagic activities. Moreover, 1H NMR spectroscopy and multivariate statistical analysis identified 11 metabolites in plasma, among which fine significantly and similarly changed after both HIIT and MICT, while BCAAs isoleucine, leucine, and valine and glutamine were changed only after HIIT. Together, these data indicate distinct differences in specific metabolites and autophagy and mitochondrial markers following HIIT vs. MICT and highlight the value of metabolomic analysis in providing more detailed insight into the metabolic adaptations to exercise training. PMID:29875683

Beneficial Autophagic Activities, Mitochondrial Function, and Metabolic Phenotype Adaptations Promoted by High-Intensity Interval Training in a Rat Model.

PubMed

Li, Fang-Hui; Li, Tao; Ai, Jing-Yi; Sun, Lei; Min, Zhu; Duan, Rui; Zhu, Ling; Liu, Yan-Ying; Liu, Timon Cheng-Yi

2018-01-01

The effects of high-intensity interval (HIIT) and moderate-intensity continuous training (MICT) on basal autophagy and mitochondrial function in cardiac and skeletal muscle and plasma metabolic phenotypes have not been clearly characterized. Here, we investigated how 10-weeks HIIT and MICT differentially modify basal autophagy and mitochondrial markers in cardiac and skeletal muscle and conducted an untargeted metabolomics study with proton nuclear magnetic resonance ( 1 H NMR) spectroscopy and multivariate statistical analysis of plasma metabolic phenotypes. Male Sprague-Dawley rats were separated into three groups: sedentary control (SED), MICT, and HIIT. Rats underwent evaluation of exercise performance, including exercise tolerance and grip strength, and blood lactate levels were measured immediately after an incremental exercise test. Plasma samples were analyzed by 1 H NMR. The expression of autophagy and mitochondrial markers and autophagic flux (LC3II/LC3-I ratio) in cardiac, rectus femoris, and soleus muscle were analyzed by western blotting. Time to exhaustion and grip strength increased significantly following HIIT compared with that in both SED and MICT groups. Compared with those in the SED group, blood lactate level, and the expression of SDH, COX-IV, and SIRT3 significantly increased in rectus femoris and soleus muscle of both HIIT and MICT groups. Meanwhile, SDH and COX-IV content of cardiac muscle and COX-IV and SIRT3 content of rectus femoris and soleus muscle increased significantly following HIIT compared with that following MICT. The expression of LC3-II, ATG-3, and Beclin-1 and LC3II/LC3-I ratio were significantly increased only in soleus and cardiac muscle following HIIT. These data indicate that HIIT was more effective for improving physical performance and facilitating cardiac and skeletal muscle adaptations that increase mitochondrial function and basal autophagic activities. Moreover, 1 H NMR spectroscopy and multivariate statistical analysis identified 11 metabolites in plasma, among which fine significantly and similarly changed after both HIIT and MICT, while BCAAs isoleucine, leucine, and valine and glutamine were changed only after HIIT. Together, these data indicate distinct differences in specific metabolites and autophagy and mitochondrial markers following HIIT vs. MICT and highlight the value of metabolomic analysis in providing more detailed insight into the metabolic adaptations to exercise training.

Targeted Temperature Management After Pediatric Cardiac Arrest Due To Drowning: Outcomes and Complications.

PubMed

Moler, Frank W; Hutchison, Jamie S; Nadkarni, Vinay M; Silverstein, Faye S; Meert, Kathleen L; Holubkov, Richard; Page, Kent; Slomine, Beth S; Christensen, James R; Dean, J Michael

2016-08-01

To describe outcomes and complications in the drowning subgroup from the Therapeutic Hypothermia After Pediatric Cardiac Arrest Out-of-Hospital trial. Exploratory post hoc cohort analysis. Twenty-four PICUs. Pediatric drowning cases. Therapeutic hypothermia versus therapeutic normothermia. An exploratory study of pediatric drowning from the Therapeutic Hypothermia After Pediatric Cardiac Arrest Out-of-Hospital trial was conducted. Comatose patients aged more than 2 days and less than 18 years were randomized up to 6 hours following return-of-circulation to hypothermia (n = 46) or normothermia (n = 28). Outcomes assessed included 12-month survival with a Vineland Adaptive Behavior Scale score of greater than or equal to 70, 1-year survival rate, change in Vineland Adaptive Behavior Scale-II score from prearrest to 12 months, and select safety measures. Seventy-four drowning cases were randomized. In patients with prearrest Vineland Adaptive Behavior Scale-II greater than or equal to 70 (n = 65), there was no difference in 12-month survival with Vineland Adaptive Behavior Scale-II score of greater than or equal to 70 between hypothermia and normothermia groups (29% vs 17%; relative risk, 1.74; 95% CI, 0.61-4.95; p = 0.27). Among all evaluable patients (n = 68), the Vineland Adaptive Behavior Scale-II score change from baseline to 12 months did not differ (p = 0.46), and 1-year survival was similar (49% hypothermia vs 42%, normothermia; relative risk, 1.16; 95% CI, 0.68-1.99; p = 0.58). Hypothermia was associated with a higher prevalence of positive bacterial culture (any blood, urine, or respiratory sample; 67% vs 43%; p = 0.04); however, the rate per 100 days at risk did not differ (11.1 vs 8.4; p = 0.46). Cumulative incidence of blood product use, serious arrhythmias, and 28-day mortality were not different. Among patients with cardiopulmonary resuscitation durations more than 30 minutes or epinephrine doses greater than 4, none had favorable Pediatric Cerebral Performance Category outcomes (≤ 3). In comatose survivors of out-of-hospital pediatric cardiac arrest due to drowning, hypothermia did not result in a statistically significant benefit in survival with good functional outcome or mortality at 1 year, as compared with normothermia. High risk of culture-proven bacterial infection was observed in both groups.

Mg2+ activates the ryanodine receptor type 2 (RyR2) at intermediate Ca2+ concentrations.

PubMed

Chugun, Akihito; Sato, Osamu; Takeshima, Hiroshi; Ogawa, Yasuo

2007-01-01

To clarify whether activity of the ryanodine receptor type 2 (RyR2) is reduced in the sarcoplasmic reticulum (SR) of cardiac muscle, as is the case with the ryanodine receptor type 1 (RyR1), Ca(2+)-dependent [(3)H]ryanodine binding, a biochemical measure of Ca(2+)-induced Ca(2+) release (CICR), was determined using SR vesicle fractions isolated from rabbit and rat cardiac muscles. In the absence of an adenine nucleotide or caffeine, the rat SR showed a complicated Ca(2+) dependence, instead of the well-documented biphasic dependence of the rabbit SR. In the rat SR, [(3)H]ryanodine binding initially increased as [Ca(2+)] increased, with a plateau in the range of 10-100 microM Ca(2+), and thereafter further increased to an apparent peak around 1 mM Ca(2+), followed by a decrease. In the presence of these modulators, this complicated dependence prevailed, irrespective of the source. Addition of 0.3-1 mM Mg(2+) unexpectedly increased the binding two- to threefold and enhanced the affinity for [(3)H]ryanodine at 10-100 microM Ca(2+), resulting in the well-known biphasic dependence. In other words, the partial suppression of RyR2 is relieved by Mg(2+). Ca(2+) could be a substitute for Mg(2+). Mg(2+) also amplifies the responses of RyR2 to inhibitory and stimulatory modulators. This stimulating effect of Mg(2+) on RyR2 is entirely new, and is referred to as the third effect, in addition to the well-known dual inhibitory effects. This effect is critical to describe the role of RyR2 in excitation-contraction coupling of cardiac muscle, in view of the intracellular Mg(2+) concentration.

Myocardial adaption to HI(R)T in previously untrained men with a randomized, longitudinal cardiac MR imaging study (Physical adaptions in Untrained on Strength and Heart trial, PUSH-trial).

PubMed

Scharf, Michael; Oezdemir, Derya; Schmid, Axel; Kemmler, Wolfgang; von Stengel, Simon; May, Matthias S; Uder, Michael; Lell, Michael M

2017-01-01

Although musculoskeletal effects in resistance training are well described, little is known about structural and functional cardiac adaption in formerly untrained subjects. We prospectively evaluated whether short term high intensity (resistance) training (HI(R)T) induces detectable morphologic cardiac changes in previously untrained men in a randomized controlled magnetic resonance imaging (MRI) study. 80 untrained middle-aged men were randomly assigned to a HI(R)T-group (n = 40; 43.5±5.9 years) or an inactive control group (n = 40; 42.0±6.3 years). HI(R)T comprised 22 weeks of training focusing on a single-set to failure protocol in 2-3 sessions/week, each with 10-13 exercises addressing main muscle groups. Repetitions were decreased from 8-10 to 3-5 during study period. Before and after HI(R)T all subjects underwent physiologic examination and cardiac MRI (cine imaging, tagging). Indexed left (LV) and right ventricular (RV) volume (LV: 76.8±15.6 to 78.7±14.8 ml/m2; RV: 77.0±15.5 to 78.7±15.1 ml/m2) and mass (LV: 55.5±9.7 to 57.0±8.8 g/m2; RV: 14.6±3.0 to 15.0±2.9 g/m2) significantly increased with HI(R)T (all p<0.001). Mean LV and RV remodeling indices of HI(R)T-group did not alter with training (0.73g/mL and 0.19g/mL, respectively [p = 0.96 and p = 0.87]), indicating balanced cardiac adaption. Indexed LV (48.4±11.1 to 50.8±11.0 ml/m2) and RV (48.5±11.0 to 50.6±10.7 ml/m2) stroke volume significantly increased with HI(R)T (p<0.001). Myocardial strain and strain rates did not change following resistance exercise. Left atrial volume at end systole slightly increased after HI(R)T (36.2±7.9 to 37.0±8.4 ml/m2, p = 0.411), the ratio to end-diastolic LV volume at baseline and post-training was unchanged (0.47 vs. 0.47, p = 0.79). 22 weeks of HI(R)T lead to measurable, physiological changes in cardiac atrial and ventricular morphologic characteristics and function in previously untrained men. The PUSH-trial is registered at the US National Institutes of Health (ClinicalTrials.gov), NCT01766791.

Extreme respiratory sinus arrhythmia enables overwintering black bear survival--physiological insights and applications to human medicine.

PubMed

Laske, Timothy G; Harlow, Henry J; Garshelis, David L; Iaizzo, Paul A

2010-10-01

American black bears survive winter months without food and water while in a mildly hypothermic, hypometabolic, and inactive state, yet they appear to be able to return to near-normal systemic function within minutes of arousal. This study's goal was to characterize the cardiovascular performance of overwintering black bears and elicit the underlying mechanisms enabling survival. Mid-winter cardiac electrophysiology was assessed in four wild black bears using implanted data recorders. Paired data from early and late winter were collected from 37 wild bears, which were anesthetized and temporarily removed from their dens to record cardiac electrophysiological parameters (12-lead electrocardiograms) and cardiac dimensional changes (echocardiography). Left ventricular thickness, primary cardiac electrophysiological parameters, and cardiovascular response to threats ("fight or flight" response) were preserved throughout winter. Dramatic respiratory sinus arrhythmias were recorded (cardiac cycle length variations up to 865%) with long sinus pauses between breaths (up to 13 s). The accelerated heart rate during breathing efficiently transports oxygen, with the heart "resting" between breaths to minimize energy usage. This adaptive cardiac physiology may have broad implications for human medicine.

Evaluation of cardiac function in active and hibernating grizzly bears.

PubMed

Nelson, O Lynne; McEwen, Margaret-Mary; Robbins, Charles T; Felicetti, Laura; Christensen, William F

2003-10-15

To evaluate cardiac function parameters in a group of active and hibernating grizzly bears. Prospective study. 6 subadult grizzly bears. Indirect blood pressure, a 12-lead ECG, and a routine echocardiogram were obtained in each bear during the summer active phase and during hibernation. All measurements of myocardial contractility were significantly lower in all bears during hibernation, compared with the active period. Mean rate of circumferential left ventricular shortening, percentage fractional shortening, and percentage left ventricular ejection fraction were significantly lower in bears during hibernation, compared with the active period. Certain indices of diastolic function appeared to indicate enhanced ventricular compliance during the hibernation period. Mean mitral inflow ratio and isovolumic relaxation time were greater during hibernation. Heart rate was significantly lower for hibernating bears, and mean cardiac index was lower but not significantly different from cardiac index during the active phase. Contrary to results obtained in hibernating rodent species, cardiac index was not significantly correlated with heart rate. Cardiac function parameters in hibernating bears are opposite to the chronic bradycardic effects detected in nonhibernating species, likely because of intrinsic cardiac muscle adaptations during hibernation. Understanding mechanisms and responses of the myocardium during hibernation could yield insight into mechanisms of cardiac function regulation in various disease states in nonhibernating species.

Fropofol decreases force development in cardiac muscle.

PubMed

Ren, Xianfeng; Schmidt, William; Huang, Yiyuan; Lu, Haisong; Liu, Wenjie; Bu, Weiming; Eckenhoff, Roderic; Cammarato, Anthony; Gao, Wei Dong

2018-03-09

Supranormal contractile properties are frequently associated with cardiac diseases. Anesthetic agents, including propofol, can depress myocardial contraction. We tested the hypothesis that fropofol, a propofol derivative, reduces force development in cardiac muscles via inhibition of cross-bridge cycling and may therefore have therapeutic potential. Force and intracellular Ca 2+ ([Ca 2+ ] i ) transients of rat trabecular muscles were determined. Myofilament ATPase, actin-activated myosin ATPase, and velocity of actin filaments propelled by myosin were also measured. Fropofol dose dependently decreased force without altering [Ca 2+ ] i in normal and pressure-induced hypertrophied-hypercontractile muscles. Similarly, fropofol depressed maximum Ca 2+ -activated force ( F max ) and increased the [Ca 2+ ] i required for 50% activation at steady-state (Ca 50 ) without affecting the Hill coefficient in both intact and skinned cardiac fibers. The drug also depressed cardiac myofibrillar and actin-activated myosin ATPase activity. In vitro actin sliding velocity was significantly reduced when fropofol was introduced during rigor binding of cross-bridges. The data suggest that the depressing effects of fropofol on cardiac contractility are likely to be related to direct targeting of actomyosin interactions. From a clinical standpoint, these findings are particularly significant, given that fropofol is a nonanesthetic small molecule that decreases myocardial contractility specifically and thus may be useful in the treatment of hypercontractile cardiac disorders.-Ren, X., Schmidt, W., Huang, Y., Lu, H., Liu, W., Bu, W., Eckenhoff, R., Cammarato, A., Gao, W. D. Fropofol decreases force development in cardiac muscle.

Streptococcus pneumoniae Translocates into the Myocardium and Forms Unique Microlesions That Disrupt Cardiac Function

PubMed Central

Brown, Armand O.; Mann, Beth; Gao, Geli; Hankins, Jane S.; Humann, Jessica; Giardina, Jonathan; Faverio, Paola; Restrepo, Marcos I.; Halade, Ganesh V.; Mortensen, Eric M.; Lindsey, Merry L.; Hanes, Martha; Happel, Kyle I.; Nelson, Steve; Bagby, Gregory J.; Lorent, Jose A.; Cardinal, Pablo; Granados, Rosario; Esteban, Andres; LeSaux, Claude J.; Tuomanen, Elaine I.; Orihuela, Carlos J.

2014-01-01

Hospitalization of the elderly for invasive pneumococcal disease is frequently accompanied by the occurrence of an adverse cardiac event; these are primarily new or worsened heart failure and cardiac arrhythmia. Herein, we describe previously unrecognized microscopic lesions (microlesions) formed within the myocardium of mice, rhesus macaques, and humans during bacteremic Streptococcus pneumoniae infection. In mice, invasive pneumococcal disease (IPD) severity correlated with levels of serum troponin, a marker for cardiac damage, the development of aberrant cardiac electrophysiology, and the number and size of cardiac microlesions. Microlesions were prominent in the ventricles, vacuolar in appearance with extracellular pneumococci, and remarkable due to the absence of infiltrating immune cells. The pore-forming toxin pneumolysin was required for microlesion formation but Interleukin-1β was not detected at the microlesion site ruling out pneumolysin-mediated pyroptosis as a cause of cell death. Antibiotic treatment resulted in maturing of the lesions over one week with robust immune cell infiltration and collagen deposition suggestive of long-term cardiac scarring. Bacterial translocation into the heart tissue required the pneumococcal adhesin CbpA and the host ligands Laminin receptor (LR) and Platelet-activating factor receptor. Immunization of mice with a fusion construct of CbpA or the LR binding domain of CbpA with the pneumolysin toxoid L460D protected against microlesion formation. We conclude that microlesion formation may contribute to the acute and long-term adverse cardiac events seen in humans with IPD. PMID:25232870

Role of Myofibril-Inducing RNA in cardiac TnT expression in developing Mexican axolotl

PubMed Central

Sferrazza, Gian-Franco; Zhang, Chi; Jia, Pingping; Lemanski, Sharon L.; Athauda, Gagani; Stassi, Alyssa; Halager, Kristine; Maier, Jennifer A.; Rueda-de-Leon, Elena; Gupta, Amit; Dube, Syamalima; Huang, Xupei; Prentice, Howard M.; Dube, Dipak K.; Lemanski, Larry F.

2007-01-01

The Mexican axolotl, Ambystoma mexicanum, has been a useful animal model to study heart development and cardiac myofibrillogenesis. A naturally-occurring recessive mutant, gene “c”, for cardiac non-function in the Mexican axolotl causes a failure of myofibrillogenesis due to a lack of tropomyosin expression in homozygous mutant (c/c) embryonic hearts.. Myofibril-Inducing RNA (MIR) rescues mutant hearts in vitro by promoting tropomyosin expression and myofibril formation thereafter. We have studied the effect of MIR on the expression of various isoforms of cardiac Troponin-T (cTnT), a component of the thin filament that binds with tropomyosin. Four alternatively spliced cTnT isoforms have been characterized from developing axolotl heart. The expression of various cTnT isoforms in normal, mutant, and mutant hearts corrected with MIR, is evaluated by real-time RT-PCR using isoform specific primer pairs; MIR affects the total transcription as well as the splicing of the cTnT in axolotl heart PMID:17408593

mAKAP – A Master Scaffold for Cardiac Remodeling

PubMed Central

Passariello, Catherine L.; Li, Jinliang; Dodge-Kafka, Kimberly; Kapiloff, Michael S.

2014-01-01

Cardiac remodeling is regulated by an extensive intracellular signal transduction network. Each of the many signaling pathways in this network contributes uniquely to the control of cellular adaptation. In the last few years, it has become apparent that multimolecular signaling complexes or ‘signalosomes’ are important for fidelity in intracellular signaling and for mediating crosstalk between the different signaling pathways. These complexes integrate upstream signals and control downstream effectors. In the cardiac myocyte, the protein mAKAPβ serves as a scaffold for a large signalosome that is responsive to cAMP, calcium, hypoxia, and mitogen-activated protein kinase signaling. The main function of mAKAPβ signalosomes is to modulate stress-related gene expression regulated by the transcription factors NFATc, MEF2 and HIF-1α and type II histone deacetylases that control pathological cardiac hypertrophy. PMID:25551320

Redox regulation of myocardial ERK 1/2 phosphorylation in experimental hyperthyroidism: role of thioredoxin-peroxiredoxin system.

PubMed

Araujo, Alex Sander da Rosa; Fernandes, Tania; Ribeiro, Maria Flavia; Khaper, Neelam; Belló-Klein, Adriane

2010-11-01

The present study was conducted to test whether adaptation in the antioxidant system would differentially modulate prosurvival and proapoptotic proteins in hyperthyroidism-induced cardiac hypertrophy. Male Wistar rats were divided into 4 groups: control, vitamin E (20 mg · kg(-1) · d(-1) subcutaneously, 28 days), thyroxine (T4) (12 mg/L in drinking water for 28 days), and T4 + vitamin E. Cardiac mass, redox ratio, glutathione peroxidase (GPx) and glutathione reductase (GR) activities, NF-E2-related factor 2 (Nrf2) thioredoxin-1 (Trx-1), peroxiredoxin-6 (Prx-6), phospho-extracellular-signal-regulated kinases 1/2 (p-ERK 1/2)/extracellular-signal-regulated kinases 1/2 (ERK1/2), and phospho-c-Jun N-terminal kinase (p-JNK)/c-Jun N-terminal kinase (JNK) myocardial protein expression were quantified. Cardiac hypertrophy was attenuated in the T4 + vitamin E group. The redox ratio; GPx and GR; as well as Nrf2, Trx-1, Prx-6, and p-ERK1/2/ERK1/2 immunocontent were elevated in T4 group. All these effects were attenuated by vitamin E administration. p-JNK/JNK remained unchanged in all the groups. The overall results suggest that redox imbalance due to hyperthyroidism induce adaptation of antioxidant systems, favoring ERK1/2 activation and leading to development of cardiac hypertrophy.

Integration of multiple cell-matrix interactions into alginate scaffolds for promoting cardiac tissue regeneration.

PubMed

Sapir, Yulia; Kryukov, Olga; Cohen, Smadar

2011-03-01

Cardiac tissue engineering aims to repair damaged myocardial tissues by applying heart patches created in vitro. Herein, we explored the possible role of a combination of two matrix-attached peptides, the adhesion peptide G(4)RGDY and heparin-binding peptide G(4)SPPRRARVTY (HBP) in cardiac tissue regeneration. Neonatal rat cardiac cells were seeded into unmodified, single peptide or double peptide-attached alginate scaffolds, all having the same physical features of porosity, hydrogel forming and matrix stiffness. The cardiac tissue developed in the HBP/RGD-attached scaffolds revealed the best features of a functional muscle tissue, as judged by all studied parameters, i.e., immunostaining of cardiac cell markers, histology, western blot of protein expressions and metabolic activity. By day 7, well-developed myocardial fibers were observed in these cell constructs. At 14 days the HBP/RGD-attached constructs presented an isotropic myofiber arrangement, while no such arrangement was seen in the other constructs. The expression levels of α-actinin, N-cadherin and Connexin-43, showing preservation and an increase in Connexin-43 expression (Cx-43) with time, further supported the formation a contractile muscle tissue in the HBP/RGD-attached scaffolds. Collectively, the attachment of combinatorial peptides representing different signaling in ECM-cell interactions proved to play a key role, contributing to the formation of a functional cardiac muscle tissue, in vitro. Copyright © 2010 Elsevier Ltd. All rights reserved.

Inhibition of myeloid differentiation factor-2 attenuates obesity-induced cardiomyopathy and fibrosis.

PubMed

Fang, Qilu; Wang, Jingying; Zhang, Yali; Wang, Lintao; Li, Weixin; Han, Jibo; Huang, Weijian; Liang, Guang; Wang, Yi

2018-01-01

Obesity causes cardiovascular diseases, including cardiac hypertrophy and remodeling, via chronic tissue inflammation. Myeloid differentiation factor-2 (MD2), a binding protein of lipopolysaccharide, is functionally essential for the activation of proinflammatory pathways in endotoxin-induced acute inflammatory diseases. Here we tested the hypothesis that MD2 plays a central role in obesity-induced cardiomyopathy. Wildtype or MD2 knockout mice were fed with a high fat diet (HFD) or normal diet (Control) for total 16weeks, and MD2 inhibitor L6H21 (20mg/kg) or vehicle (1% CMC-Na) were administered from the beginning of the 9th week. HFD induced significant weight gain and cardiac hypertrophy, with increased cardiac fibrosis and inflammation. L6H21 administration or MD2 knockout attenuated HFD-induced obesity, inflammation and cardiac remodeling. In vitro exposure of H9C2 cells to high lipids induced cell hypertrophy with activated JNK/ERK and NF-κB pathways, which was abolished by pretreatment of MD2 inhibitor L6H21. Our results demonstrate that MD2 is essential to obesity-related cardiac hypertrophy through activating JNK/ERK and NF-κB-dependent cardiac inflammatory pathways. Targeting MD2 would be a therapeutic approach to prevent obesity-induced cardiac injury and remodeling. Copyright © 2017. Published by Elsevier B.V.

p38α Mitogen-Activated Protein Kinase Plays a Critical Role in Cardiomyocyte Survival but Not in Cardiac Hypertrophic Growth in Response to Pressure Overload

PubMed Central

Nishida, Kazuhiko; Yamaguchi, Osamu; Hirotani, Shinichi; Hikoso, Shungo; Higuchi, Yoshiharu; Watanabe, Tetsuya; Takeda, Toshihiro; Osuka, Soh; Morita, Takashi; Kondoh, Gen; Uno, Yoshihiro; Kashiwase, Kazunori; Taniike, Masayuki; Nakai, Atsuko; Matsumura, Yasushi; Miyazaki, Jun-ichi; Sudo, Tatsuhiko; Hongo, Kenichi; Kusakari, Yoichiro; Kurihara, Satoshi; Chien, Kenneth R.; Takeda, Junji; Hori, Masatsugu; Otsu, Kinya

2004-01-01

The molecular mechanism for the transition from cardiac hypertrophy, an adaptive response to biomechanical stress, to heart failure is poorly understood. The mitogen-activated protein kinase p38α is a key component of stress response pathways in various types of cells. In this study, we attempted to explore the in vivo physiological functions of p38α in hearts. First, we generated mice with floxed p38α alleles and crossbred them with mice expressing the Cre recombinase under the control of the α-myosin heavy-chain promoter to obtain cardiac-specific p38α knockout mice. These cardiac-specific p38α knockout mice were born normally, developed to adulthood, were fertile, exhibited a normal life span, and displayed normal global cardiac structure and function. In response to pressure overload to the left ventricle, they developed significant levels of cardiac hypertrophy, as seen in controls, but also developed cardiac dysfunction and heart dilatation. This abnormal response to pressure overload was accompanied by massive cardiac fibrosis and the appearance of apoptotic cardiomyocytes. These results demonstrate that p38α plays a critical role in the cardiomyocyte survival pathway in response to pressure overload, while cardiac hypertrophic growth is unaffected despite its dramatic down-regulation. PMID:15572667

Diverse structures, functions and uses of FK506 binding proteins.

PubMed

Bonner, Julia Maeve; Boulianne, Gabrielle L

2017-10-01

FK506 (Tacrolimus), isolated from Streptomyces tsukubaenis is a powerful immunosuppressant shown to inhibit T cell activation. FK506 mediated immunosuppression requires the formation of a complex between FK506, a FK506 binding protein (FKBP) and calcineurin. Numerous FKBPs have been identified in a wide range of species, from single celled organisms to humans. FKBPs show peptidylprolyl cis/trans isomerase (PPIase) activity and have been shown to affect a wide range of cellular processes including protein folding, receptor signaling and apoptosis. FKBPs also affect numerous biological functions in addition to immunosuppression including regulation of cardiac function, neuronal function and development and have been implicated in several diseases including cardiac disease, cancer and neurodegenerative diseases such as Alzheimer's disease. More recently, FKBPs have proven useful as molecular tools for studying protein interactions, localization and functions. This review provides an overview of the current state of knowledge of FKBPs and their numerous biological functions and uses. Copyright © 2017 Elsevier Inc. All rights reserved.

Successful Treatment of Severe Carbon Monoxide Poisoning and Refractory Shock Using Extracorporeal Membrane Oxygenation.

PubMed

Teerapuncharoen, Krittika; Sharma, Nirmal S; Barker, Andrew B; Wille, Keith M; Diaz-Guzman, Enrique

2015-09-01

Carbon monoxide (CO) is the most common cause of poisoning and poisoning-related death in the United States. It is a tasteless and odorless poisonous gas produced from incomplete combustion of hydrocarbons, such as those produced by cars and heating systems. CO rapidly binds to hemoglobin to form carboxyhemoglobin, leading to tissue hypoxia, multiple-organ failure, and cardiovascular collapse. CO also binds to myocardial myoglobin, preventing oxidative phosphorylation in cardiac mitochondria and resulting in cardiac ischemia or stunning and cardiogenic pulmonary edema. Treatment of CO poisoning is mainly supportive, and supplemental oxygen remains the cornerstone of therapy, whereas hyperbaric oxygen therapy is considered for patients with evidence of neurological and myocardial injury. Extracorporeal membrane oxygenation (ECMO) has been utilized effectively in patients with respiratory failure and hemodynamic instability, but its use has rarely been reported in patients with CO poisoning. We report the successful use of venoarterial ECMO in a patient with severe CO poisoning and multiple-organ failure. Copyright © 2015 by Daedalus Enterprises.

Rearrangement of the Protein Phosphatase 1 Interactome During Heart Failure Progression.

PubMed

Chiang, David Y; Alsina, Katherina M; Corradini, Eleonora; Fitzpatrick, Martin; Ni, Li; Lahiri, Satadru K; Reynolds, Julia; Pan, Xiaolu; Scott, Larry; Heck, Albert J R; Wehrens, Xander H

2018-04-18

Background -Heart failure (HF) is a complex disease with a rising prevalence despite advances in treatment. Protein phosphatase 1 (PP1) has long been implicated in HF pathogenesis but its exact role is both unclear and controversial. Most previous studies measured only the PP1 catalytic subunit (PP1c) without investigating its diverse set of interactors, which confer localization and substrate specificity to the holoenzyme. In this study we define the PP1 interactome in cardiac tissue and test the hypothesis that this interactome becomes rearranged during HF progression at the level of specific PP1c interactors. Methods -Mice were subjected to transverse aortic constriction and grouped based on ejection fraction (EF) into sham, hypertrophy, moderate HF (EF 30-40%), and severe HF (EF<30%). Cardiac lysates were subjected to affinity-purification using anti-PP1c antibodies followed by high-resolution mass spectrometry. Ppp1r7 was knocked down in mouse cardiomyocytes and HeLa cells using adeno-associated virus serotype 9 (AAV9) and siRNA, respectively. Calcium imaging was performed on isolated ventricular myocytes. Results -Seventy-one and 98 PP1c interactors were quantified from mouse cardiac and HeLa lysates, respectively, including many novel interactors and protein complexes. This represents the largest reproducible PP1 interactome dataset ever captured from any tissue, including both primary and secondary/tertiary interactors. Nine PP1c interactors with changes in their binding to PP1c were strongly associated with HF progression including two known (Ppp1r7, Ppp1r18) and 7 novel interactors. Within the entire cardiac PP1 interactome, Ppp1r7 had the highest binding to PP1c. Cardiac-specific knockdown in mice led to cardiac dysfunction and disruption of calcium release from the sarcoplasmic reticulum. Conclusions -PP1 is best studied at the level of its interactome, which undergoes significant rearrangement during HF progression. The nine key interactors that are associated with HF progression may represent potential targets in HF therapy. In particular, Ppp1r7 may play a central role in regulating the PP1 interactome by acting as a competitive molecular "sponge" of PP1c.

LncRNA ZFAS1 as a SERCA2a Inhibitor to Cause Intracellular Ca2+ Overload and Contractile Dysfunction in a Mouse Model of Myocardial Infarction.

PubMed

Zhang, Ying; Jiao, Lei; Sun, Lihua; Li, Yanru; Gao, Yuqiu; Xu, Chaoqian; Shao, Yingchun; Li, Mengmeng; Li, Chunyan; Lu, Yanjie; Pan, Zhenwei; Xuan, Lina; Zhang, Yiyuan; Li, Qingqi; Yang, Rui; Zhuang, Yuting; Zhang, Yong; Yang, Baofeng

2018-05-11

Ca 2+ homeostasis-a critical determinant of cardiac contractile function-is critically regulated by SERCA2a (sarcoplasmic reticulum Ca 2+ -ATPase 2a). Our previous study has identified ZFAS1 as a new lncRNA biomarker of acute myocardial infarction (MI). To evaluate the effects of ZFAS1 on SERCA2a and the associated Ca 2+ homeostasis and cardiac contractile function in the setting of MI. ZFAS1 expression was robustly increased in cytoplasm and sarcoplasmic reticulum in a mouse model of MI and a cellular model of hypoxia. Knockdown of endogenous ZFAS1 by virus-mediated silencing shRNA partially abrogated the ischemia-induced contractile dysfunction. Overexpression of ZFAS1 in otherwise normal mice created similar impairment of cardiac function as that observed in MI mice. Moreover, at the cellular level, ZFAS1 overexpression weakened the contractility of cardiac muscles. At the subcellular level, ZFAS1 deleteriously altered the Ca 2+ transient leading to intracellular Ca 2+ overload in cardiomyocytes. At the molecular level, ZFAS1 was found to directly bind SERCA2a protein and to limit its activity, as well as to repress its expression. The effects of ZFAS1 were readily reversible on knockdown of this lncRNA. Notably, a sequence domain of ZFAS1 gene that is conserved across species mimicked the effects of the full-length ZFAS1 . Mutation of this domain or application of an antisense fragment to this conserved region efficiently canceled out the deleterious actions of ZFAS1 . ZFAS1 had no significant effects on other Ca 2+ -handling regulatory proteins. ZFAS1 is an endogenous SERCA2a inhibitor, acting by binding to SERCA2a protein to limit its intracellular level and inhibit its activity, and a contributor to the impairment of cardiac contractile function in MI. Therefore, anti- ZFAS1 might be considered as a new therapeutic strategy for preserving SERCA2a activity and cardiac function under pathological conditions of the heart. © 2018 The Authors.

Minocycline reduces neuronal death and attenuates microglial response after pediatric asphyxial cardiac arrest.

PubMed

Tang, Minke; Alexander, Henry; Clark, Robert S B; Kochanek, Patrick M; Kagan, Valerian E; Bayir, Hülya

2010-01-01

The mechanisms leading to delayed neuronal death after asphyxial cardiac arrest (ACA) in the developing brain are unknown. This study aimed at investigating the possible role of microglial activation in neuronal death in developing brain after ACA. Postnatal day-17 rats were subjected to 9 mins of ACA followed by resuscitation. Rats were randomized to treatment with minocycline, (90 mg/kg, intraperitoneally (i.p.)) or vehicle (saline, i.p.) at 1 h after return of spontaneous circulation. Thereafter, minocycline (22.5 mg/kg, i.p.) was administrated every 12 h until sacrifice. Microglial activation (evaluated by immunohistochemistry using ionized calcium-binding adapter molecule-1 (Iba1) antibody) coincided with DNA fragmentation and neurodegeneration in CA1 hippocampus and cortex (assessed by deoxynucleotidyltransferase-mediated dUTP nick-end labeling (TUNEL), Fluoro-Jade-B and Nissl stain). Minocycline significantly decreased both the microglial response and neuronal degeneration compared with the vehicle. Asphyxial CA significantly enhanced proinflammatory cytokine and chemokine levels in hippocampus versus control (assessed by multiplex bead array assay), specifically tumor necrosis factor-alpha (TNF-alpha), macrophage inflammatory protein-1alpha (MIP-1alpha), regulated upon activation, normal T-cell expressed and secreted (RANTES), and growth-related oncogene (GRO-KC) (P<0.05). Minocycline attenuated ACA-induced increases in MIP-1alpha and RANTES (P<0.05). These data show that microglial activation and cytokine production are increased in immature brain after ACA. The beneficial effect of minocycline suggests an important role for microglia in selective neuronal death after pediatric ACA, and a possible therapeutic target.

Pay attention to cardiac remodeling in cancer cachexia.

PubMed

Zheng, Yawen; Chen, Han; Li, Xiaoqing; Sun, Yuping

2016-07-01

Cancer cachexia is a complex and multifaceted disease state characterized by fatigue, weakness, and loss of skeletal muscle and adipose tissue. Recently, the profound negative effects of cancer cachexia on cardiac tissue draw much attention, which is likely to contribute to mortality in tumor-bearing animals. The mechanism of cardiac remodeling is not so clear and involved with a series of molecular alterations. In cancer cachexia model, progressive loss of left ventricular mass and decrease in myocardial function is observed and cardiac autonomic functions are altered. Levels of several emerging cardiovascular neurohormones are found elevating in patients with cancer, but it is still controversial whether the changes could reflect the heart injury accurately. The remedy for cardiac remodeling has been explored. It is showed that exercise can modulate signaling pathways activated by wasting cytokines and impact on the resulting outcomes on heart adaptation. Some drugs, such as bisoprolol, spironolactone, perindopril, tandospirone, and simvastatin, can mitigate adverse effects of the tumor on the heart and prolong survival.

Temporal partitioning of adaptive responses of the murine heart to fasting.

PubMed

Brewer, Rachel A; Collins, Helen E; Berry, Ryan D; Brahma, Manoja K; Tirado, Brian A; Peliciari-Garcia, Rodrigo A; Stanley, Haley L; Wende, Adam R; Taegtmeyer, Heinrich; Rajasekaran, Namakkal Soorappan; Darley-Usmar, Victor; Zhang, Jianhua; Frank, Stuart J; Chatham, John C; Young, Martin E

2018-03-15

Recent studies suggest that the time of day at which food is consumed dramatically influences clinically-relevant cardiometabolic parameters (e.g., adiposity, insulin sensitivity, and cardiac function). Meal feeding benefits may be the result of daily periods of feeding and/or fasting, highlighting the need for improved understanding of the temporal adaptation of cardiometabolic tissues (e.g., heart) to fasting. Such studies may provide mechanistic insight regarding how time-of-day-dependent feeding/fasting cycles influence cardiac function. We hypothesized that fasting during the sleep period elicits beneficial adaptation of the heart at transcriptional, translational, and metabolic levels. To test this hypothesis, temporal adaptation was investigated in wild-type mice fasted for 24-h, or for either the 12-h light/sleep phase or the 12-h dark/awake phase. Fasting maximally induced fatty acid responsive genes (e.g., Pdk4) during the dark/active phase; transcriptional changes were mirrored at translational (e.g., PDK4) and metabolic flux (e.g., glucose/oleate oxidation) levels. Similarly, maximal repression of myocardial p-mTOR and protein synthesis rates occurred during the dark phase; both parameters remained elevated in the heart of fasted mice during the light phase. In contrast, markers of autophagy (e.g., LC3II) exhibited peak responses to fasting during the light phase. Collectively, these data show that responsiveness of the heart to fasting is temporally partitioned. Autophagy peaks during the light/sleep phase, while repression of glucose utilization and protein synthesis is maximized during the dark/active phase. We speculate that sleep phase fasting may benefit cardiac function through augmentation of protein/cellular constituent turnover. Copyright © 2018 Elsevier Inc. All rights reserved.

Disturbance of cardiac gene expression and cardiomyocyte structure predisposes Mecp2-null mice to arrhythmias

PubMed Central

Hara, Munetsugu; Takahashi, Tomoyuki; Mitsumasu, Chiaki; Igata, Sachiyo; Takano, Makoto; Minami, Tomoko; Yasukawa, Hideo; Okayama, Satoko; Nakamura, Keiichiro; Okabe, Yasunori; Tanaka, Eiichiro; Takemura, Genzou; Kosai, Ken-ichiro; Yamashita, Yushiro; Matsuishi, Toyojiro

2015-01-01

Methyl-CpG-binding protein 2 (MeCP2) is an epigenetic regulator of gene expression that is essential for normal brain development. Mutations in MeCP2 lead to disrupted neuronal function and can cause Rett syndrome (RTT), a neurodevelopmental disorder. Previous studies reported cardiac dysfunction, including arrhythmias in both RTT patients and animal models of RTT. In addition, recent studies indicate that MeCP2 may be involved in cardiac development and dysfunction, but its role in the developing and adult heart remains unknown. In this study, we found that Mecp2-null ESCs could differentiate into cardiomyocytes, but the development and further differentiation of cardiovascular progenitors were significantly affected in MeCP2 deficiency. In addition, we revealed that loss of MeCP2 led to dysregulation of endogenous cardiac genes and myocardial structural alterations, although Mecp2-null mice did not exhibit obvious cardiac functional abnormalities. Furthermore, we detected methylation of the CpG islands in the Tbx5 locus, and showed that MeCP2 could target these sequences. Taken together, these results suggest that MeCP2 is an important regulator of the gene-expression program responsible for maintaining normal cardiac development and cardiomyocyte structure. PMID:26073556

A Numerical Study of Scalable Cardiac Electro-Mechanical Solvers on HPC Architectures

PubMed Central

Colli Franzone, Piero; Pavarino, Luca F.; Scacchi, Simone

2018-01-01

We introduce and study some scalable domain decomposition preconditioners for cardiac electro-mechanical 3D simulations on parallel HPC (High Performance Computing) architectures. The electro-mechanical model of the cardiac tissue is composed of four coupled sub-models: (1) the static finite elasticity equations for the transversely isotropic deformation of the cardiac tissue; (2) the active tension model describing the dynamics of the intracellular calcium, cross-bridge binding and myofilament tension; (3) the anisotropic Bidomain model describing the evolution of the intra- and extra-cellular potentials in the deforming cardiac tissue; and (4) the ionic membrane model describing the dynamics of ionic currents, gating variables, ionic concentrations and stretch-activated channels. This strongly coupled electro-mechanical model is discretized in time with a splitting semi-implicit technique and in space with isoparametric finite elements. The resulting scalable parallel solver is based on Multilevel Additive Schwarz preconditioners for the solution of the Bidomain system and on BDDC preconditioned Newton-Krylov solvers for the non-linear finite elasticity system. The results of several 3D parallel simulations show the scalability of both linear and non-linear solvers and their application to the study of both physiological excitation-contraction cardiac dynamics and re-entrant waves in the presence of different mechano-electrical feedbacks. PMID:29674971

Mast cells regulate myofilament calcium sensitization and heart function after myocardial infarction

PubMed Central

Richart, Adèle; Vilar, Jose; Lemitre, Mathilde; Marck, Pauline; Branchereau, Maxime; Guerin, Coralie; Gautier, Gregory; Blank, Ulrich; Heymes, Christophe; Luche, Elodie; Cousin, Béatrice; Rodewald, Hans-Reimer

2016-01-01

Acute myocardial infarction (MI) is a severe ischemic disease responsible for heart failure and sudden death. Inflammatory cells orchestrate postischemic cardiac remodeling after MI. Studies using mice with defective mast/stem cell growth factor receptor c-Kit have suggested key roles for mast cells (MCs) in postischemic cardiac remodeling. Because c-Kit mutations affect multiple cell types of both immune and nonimmune origin, we addressed the impact of MCs on cardiac function after MI, using the c-Kit–independent MC-deficient (Cpa3Cre/+) mice. In response to MI, MC progenitors originated primarily from white adipose tissue, infiltrated the heart, and differentiated into mature MCs. MC deficiency led to reduced postischemic cardiac function and depressed cardiomyocyte contractility caused by myofilament Ca2+ desensitization. This effect correlated with increased protein kinase A (PKA) activity and hyperphosphorylation of its targets, troponin I and myosin-binding protein C. MC-specific tryptase was identified to regulate PKA activity in cardiomyocytes via protease-activated receptor 2 proteolysis. This work reveals a novel function for cardiac MCs modulating cardiomyocyte contractility via alteration of PKA-regulated force–Ca2+ interactions in response to MI. Identification of this MC-cardiomyocyte cross-talk provides new insights on the cellular and molecular mechanisms regulating the cardiac contractile machinery and a novel platform for therapeutically addressable regulators. PMID:27353089

Zebrafish Cardiac Muscle Thick Filaments: Isolation Technique and Three-Dimensional Structure

PubMed Central

González-Solá, Maryví; AL-Khayat, Hind A.; Behra, Martine; Kensler, Robert W.

2014-01-01

To understand how mutations in thick filament proteins such as cardiac myosin binding protein-C or titin, cause familial hypertrophic cardiomyopathies, it is important to determine the structure of the cardiac thick filament. Techniques for the genetic manipulation of the zebrafish are well established and it has become a major model for the study of the cardiovascular system. Our goal is to develop zebrafish as an alternative system to the mammalian heart model for the study of the structure of the cardiac thick filaments and the proteins that form it. We have successfully isolated thick filaments from zebrafish cardiac muscle, using a procedure similar to those for mammalian heart, and analyzed their structure by negative-staining and electron microscopy. The isolated filaments appear well ordered with the characteristic 42.9 nm quasi-helical repeat of the myosin heads expected from x-ray diffraction. We have performed single particle image analysis on the collected electron microscopy images for the C-zone region of these filaments and obtained a three-dimensional reconstruction at 3.5 nm resolution. This reconstruction reveals structure similar to the mammalian thick filament, and demonstrates that zebrafish may provide a useful model for the study of the changes in the cardiac thick filament associated with disease processes. PMID:24739166

AKAPs: The Architectural Underpinnings of Local cAMP signaling

PubMed Central

Kritzer, Michael D.; Li, Jinliang; Dodge-Kafka, Kimberly; Kapiloff, Michael S.

2011-01-01

The cAMP-dependent protein kinase A (PKA) is targeted to specific compartments in the cardiac myocyte by A-kinase anchoring proteins (AKAPs), a diverse set of scaffold proteins that have been implicated in the regulation of excitation-contraction coupling and cardiac remodeling. AKAPs bind not only PKA, but also a large variety of structural and signaling molecules. In this review, we discuss the basic concepts underlying compartmentation of cAMP and PKA signaling, as well as a few of the individual AKAPs that have been shown to be functionally relevant in the heart. PMID:21600214

An interaction study in mammalian cells demonstrates weak binding of HSPB2 to BAG3, which is regulated by HSPB3 and abrogated by HSPB8.

PubMed

Morelli, Federica F; Mediani, Laura; Heldens, Lonneke; Bertacchini, Jessika; Bigi, Ilaria; Carrà, Arianna Dorotea; Vinet, Jonathan; Carra, Serena

2017-07-01

The ten mammalian small heat shock proteins (sHSPs/HSPBs) show a different expression profile, although the majority of them are abundant in skeletal and cardiac muscles. HSPBs form hetero-oligomers and homo-oligomers by interacting together and complexes containing, e.g., HSPB2/HSPB3 or HSPB1/HSPB5 have been documented in mammalian cells and muscles. Moreover, HSPB8 associates with the Hsc70/Hsp70 co-chaperone BAG3, in mammalian, skeletal, and cardiac muscle cells. Interaction of HSPB8 with BAG3 regulates its stability and function. Weak association of HSPB5 and HSPB6 with BAG3 has been also reported upon overexpression in cells, supporting the idea that BAG3 might indirectly modulate the function of several HSPBs. However, it is yet unknown whether other HSPBs highly expressed in muscles such as HSPB2 and HSPB3 also bind to BAG3. Here, we report that in mammalian cells, upon overexpression, HSPB2 binds to BAG3 with an affinity weaker than HSPB8. HSPB2 competes with HSPB8 for binding to BAG3. In contrast, HSPB3 negatively regulates HSPB2 association with BAG3. In human myoblasts that express HSPB2, HSPB3, HSPB8, and BAG3, the latter interacts selectively with HSPB8. Combining these data, it supports the interpretation that HSPB8-BAG3 is the preferred interaction.

On the pivotal role of PPARα in adaptation of the heart to hypoxia and why fat in the diet increases hypoxic injury

PubMed Central

Cole, Mark A.; Abd Jamil, Amira H.; Heather, Lisa C.; Murray, Andrew J.; Sutton, Elizabeth R.; Slingo, Mary; Sebag-Montefiore, Liam; Tan, Suat Cheng; Aksentijević, Dunja; Gildea, Ottilie S.; Stuckey, Daniel J.; Yeoh, Kar Kheng; Carr, Carolyn A.; Evans, Rhys D.; Aasum, Ellen; Schofield, Christopher J.; Ratcliffe, Peter J.; Neubauer, Stefan; Robbins, Peter A.; Clarke, Kieran

2016-01-01

The role of peroxisome proliferator-activated receptor α (PPARα)-mediated metabolic remodeling in cardiac adaptation to hypoxia has yet to be defined. Here, mice were housed in hypoxia for 3 wk before in vivo contractile function was measured using cine MRI. In isolated, perfused hearts, energetics were measured using 31P magnetic resonance spectroscopy (MRS), and glycolysis and fatty acid oxidation were measured using [3H] labeling. Compared with a normoxic, chow-fed control mouse heart, hypoxia decreased PPARα expression, fatty acid oxidation, and mitochondrial uncoupling protein 3 (UCP3) levels, while increasing glycolysis, all of which served to maintain normal ATP concentrations ([ATP]) and thereby, ejection fractions. A high-fat diet increased cardiac PPARα expression, fatty acid oxidation, and UCP3 levels with decreased glycolysis. Hypoxia was unable to alter the high PPARα expression or reverse the metabolic changes caused by the high-fat diet, with the result that [ATP] and contractile function decreased significantly. The adaptive metabolic changes caused by hypoxia in control mouse hearts were found to have occurred already in PPARα-deficient (PPARα−/−) mouse hearts and sustained function in hypoxia despite an inability for further metabolic remodeling. We conclude that decreased cardiac PPARα expression is essential for adaptive metabolic remodeling in hypoxia, but is prevented by dietary fat.—Cole, M. A., Abd Jamil, A. H., Heather, L. C., Murray, A. J., Sutton, E. R., Slingo, M., Sebag-Montefiore, L., Tan, S. C., Aksentijević, D., Gildea, O. S., Stuckey, D. J., Yeoh, K. K., Carr, C. A., Evans, R. D., Aasum, E., Schofield, C. J., Ratcliffe, P. J., Neubauer, S., Robbins, P. A., Clarke, K. On the pivotal role of PPARα in adaptation of the heart to hypoxia and why fat in the diet increases hypoxic injury. PMID:27103577

Cardiac atrophy after bed rest and spaceflight.

PubMed

Perhonen, M A; Franco, F; Lane, L D; Buckey, J C; Blomqvist, C G; Zerwekh, J E; Peshock, R M; Weatherall, P T; Levine, B D

2001-08-01

Cardiac muscle adapts well to changes in loading conditions. For example, left ventricular (LV) hypertrophy may be induced physiologically (via exercise training) or pathologically (via hypertension or valvular heart disease). If hypertension is treated, LV hypertrophy regresses, suggesting a sensitivity to LV work. However, whether physical inactivity in nonathletic populations causes adaptive changes in LV mass or even frank atrophy is not clear. We exposed previously sedentary men to 6 (n = 5) and 12 (n = 3) wk of horizontal bed rest. LV and right ventricular (RV) mass and end-diastolic volume were measured using cine magnetic resonance imaging (MRI) at 2, 6, and 12 wk of bed rest; five healthy men were also studied before and after at least 6 wk of routine daily activities as controls. In addition, four astronauts were exposed to the complete elimination of hydrostatic gradients during a spaceflight of 10 days. During bed rest, LV mass decreased by 8.0 +/- 2.2% (P = 0.005) after 6 wk with an additional atrophy of 7.6 +/- 2.3% in the subjects who remained in bed for 12 wk; there was no change in LV mass for the control subjects (153.0 +/- 12.2 vs. 153.4 +/- 12.1 g, P = 0.81). Mean wall thickness decreased (4 +/- 2.5%, P = 0.01) after 6 wk of bed rest associated with the decrease in LV mass, suggesting a physiological remodeling with respect to altered load. LV end-diastolic volume decreased by 14 +/- 1.7% (P = 0.002) after 2 wk of bed rest and changed minimally thereafter. After 6 wk of bed rest, RV free wall mass decreased by 10 +/- 2.7% (P = 0.06) and RV end-diastolic volume by 16 +/- 7.9% (P = 0.06). After spaceflight, LV mass decreased by 12 +/- 6.9% (P = 0.07). In conclusion, cardiac atrophy occurs during prolonged (6 wk) horizontal bed rest and may also occur after short-term spaceflight. We suggest that cardiac atrophy is due to a physiological adaptation to reduced myocardial load and work in real or simulated microgravity and demonstrates the plasticity of cardiac muscle under different loading conditions.

Cardiovascular response to prescribed detraining among recreational athletes.

PubMed

Pedlar, Charles R; Brown, Marcel G; Shave, Robert E; Otto, James M; Drane, Aimee; Michaud-Finch, Jennifer; Contursi, Miranda; Wasfy, Meagan M; Hutter, Adolph; Picard, Michael H; Lewis, Gregory D; Baggish, Aaron L

2018-04-01

Exercise-induced cardiac remodeling (EICR) and the attendant myocardial adaptations characteristic of the athlete's heart may regress during periods of exercise reduction or abstinence. The time course and mechanisms underlying this reverse remodeling, specifically the impact of concomitant plasma volume (PV) contraction on cardiac chamber size, remain incompletely understood. We therefore studied recreational runners ( n = 21, age 34 ± 7 yr; 48% male) who completed an 18-wk training program (~7 h/wk) culminating in the 2016 Boston Marathon after which total exercise exposure was confined to <2 h/wk (no single session >1 h) for 8 wk. Cardiac structure and function, exercise capacity, and PV were assessed at peak fitness (10-14 days before) and at 4 wk and 8 wk postmarathon. Mixed linear modeling adjusting for age, sex, V̇o 2peak , and marathon finish time was used to compare data across time points. Physiological detraining was evidenced by serial reductions in treadmill performance. Two distinct phases of myocardial remodeling and hematological adaptation were observed. After 4 wk of detraining, there were significant reductions in PV (Δ -6.0%, P < 0.01), left ventricular (LV) wall thickness (Δ -8.1%, <0.05), LV mass (Δ -10.3%, P < 0.001), and right atrial area (Δ -8.2%, P < 0.001). After 8 wk of detraining, there was a significant reduction in right ventricle chamber size (end-diastolic area Δ = -8.0%, P < 0.05) without further concomitant reductions in PV or LV wall thickness. Abrupt reductions in exercise training stimulus result in a structure-specific time course of reverse cardiac remodeling that occurs largely independently of PV contraction. NEW & NOTEWORTHY Significant reverse cardiac remodeling, previously documented among competitive athletes, extends to recreational runners and occurs with a distinct time course. Initial reductions in plasma volume and left ventricular (LV) mass, driven by reductions in wall thickness, are followed by contraction of the right ventricle. Consistent with data from competitive athletes, LV chamber volumes appear less responsive to detraining and may be a more permanent adaptation to sport.

Cardiac atrophy after bed rest and spaceflight

NASA Technical Reports Server (NTRS)

Perhonen, M. A.; Franco, F.; Lane, L. D.; Buckey, J. C.; Blomqvist, C. G.; Zerwekh, J. E.; Peshock, R. M.; Weatherall, P. T.; Levine, B. D.

2001-01-01

Cardiac muscle adapts well to changes in loading conditions. For example, left ventricular (LV) hypertrophy may be induced physiologically (via exercise training) or pathologically (via hypertension or valvular heart disease). If hypertension is treated, LV hypertrophy regresses, suggesting a sensitivity to LV work. However, whether physical inactivity in nonathletic populations causes adaptive changes in LV mass or even frank atrophy is not clear. We exposed previously sedentary men to 6 (n = 5) and 12 (n = 3) wk of horizontal bed rest. LV and right ventricular (RV) mass and end-diastolic volume were measured using cine magnetic resonance imaging (MRI) at 2, 6, and 12 wk of bed rest; five healthy men were also studied before and after at least 6 wk of routine daily activities as controls. In addition, four astronauts were exposed to the complete elimination of hydrostatic gradients during a spaceflight of 10 days. During bed rest, LV mass decreased by 8.0 +/- 2.2% (P = 0.005) after 6 wk with an additional atrophy of 7.6 +/- 2.3% in the subjects who remained in bed for 12 wk; there was no change in LV mass for the control subjects (153.0 +/- 12.2 vs. 153.4 +/- 12.1 g, P = 0.81). Mean wall thickness decreased (4 +/- 2.5%, P = 0.01) after 6 wk of bed rest associated with the decrease in LV mass, suggesting a physiological remodeling with respect to altered load. LV end-diastolic volume decreased by 14 +/- 1.7% (P = 0.002) after 2 wk of bed rest and changed minimally thereafter. After 6 wk of bed rest, RV free wall mass decreased by 10 +/- 2.7% (P = 0.06) and RV end-diastolic volume by 16 +/- 7.9% (P = 0.06). After spaceflight, LV mass decreased by 12 +/- 6.9% (P = 0.07). In conclusion, cardiac atrophy occurs during prolonged (6 wk) horizontal bed rest and may also occur after short-term spaceflight. We suggest that cardiac atrophy is due to a physiological adaptation to reduced myocardial load and work in real or simulated microgravity and demonstrates the plasticity of cardiac muscle under different loading conditions.

Direct association between the Ret receptor tyrosine kinase and the Src homology 2-containing adapter protein Grb7.

PubMed

Pandey, A; Liu, X; Dixon, J E; Di Fiore, P P; Dixit, V M

1996-05-03

Adapter proteins containing Src homology 2 (SH2) domains link transmembrane receptor protein-tyrosine kinases to downstream signal transducing molecules. A family of SH2 containing adapter proteins including Grb7 and Grb10 has been recently identified. We had previously shown that Grb10 associates with Ret via its SH2 domain in an activation-dependent manner (Pandey, A., Duan, H., Di Fiore, P.P., and Dixit, V.M. (1995) J. Biol, Chem. 270, 21461-21463). We now demonstrate that the related adapter molecule Grb7 also associates with Ret in vitro and in vivo, and that the binding of the SH2 domain of Grb7 to Ret is direct. This binding is dependent upon Ret autophosphorylation since Grb7 is incapable of binding a kinase-defective mutant of Ret. Thus two members of the Grb family, Grb7 and Grb10, likely relay signals emanating from Ret to other, as yet, unidentified targets within the cell.

The Gratton effect remains after controlling for contingencies and stimulus repetitions

PubMed Central

Blais, Chris; Stefanidi, Aikaterini; Brewer, Gene A.

2014-01-01

Highlights: The conflict monitoring hypothesis signals the need for cognitive controlThe Gratton effect is a key result attributed to the conflict monitoring hypothesisSome argue that controlling binding confounds eliminates the Gratton effect A Gratton effect remains in a vocal Stroop task after eliminating confounds The Gratton effect, the observation that the size of the Stroop effect is larger following a congruent trial compared to an incongruent trial, is one pivotal observation in support of the conflict-monitoring hypothesis. Previous reports have demonstrated that non-conflict components, such as feature binding, also contribute to this effect. Critically, Schmidt and De Houwer (2011) report a flanker task and a button-press Stroop task suggesting that there is no conflict adaptation in the Gratton effect; it is entirely caused by feature binding. The current investigation attempts to replicate and extend this important finding across two experiments using a canonical four-choice Stroop task with vocal responses. In contrast to Schmidt and De Houwer, we observe reliable conflict adaptation after controlling for feature binding. We argue that the overall strength of conflict is critical for determining whether a conflict adaptation component will remain in the Gratton effect after explaining binding components. PMID:25386151

Oral streptococci utilize a Siglec-like domain of serine-rich repeat adhesins to preferentially target platelet sialoglycans in human blood.

PubMed

Deng, Lingquan; Bensing, Barbara A; Thamadilok, Supaporn; Yu, Hai; Lau, Kam; Chen, Xi; Ruhl, Stefan; Sullam, Paul M; Varki, Ajit

2014-12-01

Damaged cardiac valves attract blood-borne bacteria, and infective endocarditis is often caused by viridans group streptococci. While such bacteria use multiple adhesins to maintain their normal oral commensal state, recognition of platelet sialoglycans provides an intermediary for binding to damaged valvular endocardium. We use a customized sialoglycan microarray to explore the varied binding properties of phylogenetically related serine-rich repeat adhesins, the GspB, Hsa, and SrpA homologs from Streptococcus gordonii and Streptococcus sanguinis species, which belong to a highly conserved family of glycoproteins that contribute to virulence for a broad range of Gram-positive pathogens. Binding profiles of recombinant soluble homologs containing novel sialic acid-recognizing Siglec-like domains correlate well with binding of corresponding whole bacteria to arrays. These bacteria show multiple modes of glycan, protein, or divalent cation-dependent binding to synthetic glycoconjugates and isolated glycoproteins in vitro. However, endogenous asialoglycan-recognizing clearance receptors are known to ensure that only fully sialylated glycans dominate in the endovascular system, wherein we find these particular streptococci become primarily dependent on their Siglec-like adhesins for glycan-mediated recognition events. Remarkably, despite an excess of alternate sialoglycan ligands in cellular and soluble blood components, these adhesins selectively target intact bacteria to sialylated ligands on platelets, within human whole blood. These preferred interactions are inhibited by corresponding recombinant soluble adhesins, which also preferentially recognize platelets. Our data indicate that circulating platelets may act as inadvertent Trojan horse carriers of oral streptococci to the site of damaged endocardium, and provide an explanation why it is that among innumerable microbes that gain occasional access to the bloodstream, certain viridans group streptococci have a selective advantage in colonizing damaged cardiac valves and cause infective endocarditis.

Structure, recognition and adaptive binding in RNA aptamer complexes.

PubMed

Patel, D J; Suri, A K; Jiang, F; Jiang, L; Fan, P; Kumar, R A; Nonin, S

1997-10-10

Novel features of RNA structure, recognition and discrimination have been recently elucidated through the solution structural characterization of RNA aptamers that bind cofactors, aminoglycoside antibiotics, amino acids and peptides with high affinity and specificity. This review presents the solution structures of RNA aptamer complexes with adenosine monophosphate, flavin mononucleotide, arginine/citrulline and tobramycin together with an example of hydrogen exchange measurements of the base-pair kinetics for the AMP-RNA aptamer complex. A comparative analysis of the structures of these RNA aptamer complexes yields the principles, patterns and diversity associated with RNA architecture, molecular recognition and adaptive binding associated with complex formation.

DIOL Triterpenes Block Profibrotic Effects of Angiotensin II and Protect from Cardiac Hypertrophy

PubMed Central

Jurado-López, Raquel; Martínez-Martínez, Ernesto; Gómez-Hurtado, Nieves; Delgado, Carmen; Visitación Bartolomé, Maria; San Román, José Alberto; Cordova, Claudia; Lahera, Vicente; Nieto, Maria Luisa; Cachofeiro, Victoria

2012-01-01

Background The natural triterpenes, erythrodiol and uvaol, exert anti-inflammatory, vasorelaxing and anti-proliferative effects. Angiotensin II is a well-known profibrotic and proliferative agent that participates in the cardiac remodeling associated with different pathological situations through the stimulation and proliferation of cardiac fibroblasts. Therefore, the aim of the study was to investigate the preventive effects of the natural triterpenes erythrodiol and uvaol on the proliferation and collagen production induced by angiotensin II in cardiac myofibroblasts. Their actions on cardiac hypertrophy triggered by angiotensin II were also studied. Methodology/Principal Findings The effect of erythrodiol and uvaol on angiotensin II-induced proliferation was evaluated in cardiac myofibroblasts from adult rats in the presence or the absence of the inhibitors of PPAR-γ, GW9662 or JNK, SP600125. The effect on collagen levels induced by angiotensin II was evaluated in cardiac myofibroblasts and mouse heart. The presence of low doses of both triterpenes reduced the proliferation of cardiac myofibroblasts induced by angiotensin II. Pretreatment with GW9662 reversed the effect elicited by both triterpenes while SP600125 did not modify it. Both triterpenes at high doses produced an increase in annexing-V binding in the presence or absence of angiotensin II, which was reduced by either SP600125 or GW9662. Erythrodiol and uvaol decreased collagen I and galectin 3 levels induced by angiotensin II in cardiac myofribroblasts. Finally, cardiac hypertrophy, ventricular remodeling, fibrosis, and increases in myocyte area and brain natriuretic peptide levels observed in angiotensin II-infused mice were reduced in triterpene-treated animals. Conclusions/Significance Erythrodiol and uvaol reduce cardiac hypertrophy and left ventricle remodeling induced by angiotensin II in mice by diminishing fibrosis and myocyte area. They also modulate growth and survival of cardiac myofibroblasts. They inhibit the angiotensin II-induced proliferation in a PPAR-γ-dependent manner, while at high doses they activate pathways of programmed cell death that are dependent on JNK and PPAR-γ. PMID:22844495

Improving Peripheral and Central Vascular Adjustments during Exercise through a Training Program in Adolescents with Obesity.

PubMed

Julian, Valérie; Thivel, David; Pereira, Bruno; Costes, Frédéric; Richard, Ruddy; Duclos, Martine

2016-01-01

The effects of a training program (TP) on muscle microvascularization during exercise remained to be explored in adolescents with obesity. We hypothesized that a TP would lead to better microvascular adaptations to exercise in skeletal muscle. 15 inactive adolescents followed a 12-week TP where both peripheral (muscular microvascularization) and central (cardiac) adaptations to exercise (40 min exercise set at 70% V̇O2peak) were assessed before and after intervention. Microvascular adaptations were evaluated in the Musculus vastus lateralis with near-infrared spectroscopy, by measurement of muscular blood volume (IR-BV) and tissue oxygen saturation (IR-SO2). Central adaptations were evaluated using thoracic impedance. The TP favored lower BMI (p < 0.001), lower total and abdominal fat (p < 0.001), and a trend for the decrease in insulin resistance index (p = 0.07). V̇O2peak relative to weight (p = 0.008) and maximum power output increased (p = 0.0003). A smaller initial drop in IR-BV and IR-SO2 (p < 0.001), a prompter return of these parameters to their base values, and a higher IR-BV and IR-SO2 all times taken together (p < 0.001) were observed after completing the TP. Concerning central adaptation, cardiac output decreased (p < 0.001). We demonstrate for the first time by noninvasive techniques that a training program induces peripheral and central vascular adaptations to exercise in adolescents with obesity. © 2016 The Author(s) Published by S. Karger GmbH, Freiburg.

Endogenous digitalis-like factors.

PubMed

Schoner, W

1992-01-01

The postulate of a natriuretic factor inhibiting the sodium pump in the kidney led to the detection of increased concentrations of endogenous digitalis-like factors in blood after salt loading, in essential hypertension, in pregnancy-induced hypertension and in chronic hypervolaemia. The recent isolation of ouabain or a close isomer thereof from human plasma and the demonstration of a compound similar if not identical to digoxin in adrenals and human urine shows that mammals like non-vertebrates and toads may synthesize cardiac glycosides in their adrenals and possibly in hypothalamus. The hypothalamus also forms other compounds of unknown structure which bind to the cardiac glycoside receptor site. The differential functions of endogenously formed ouabain and of a digoxin-like substance are unclear. The detailed knowledge of the physiological role of both endogenously formed cardiac glycosides in the regulation of blood pressure has still to be worked out.

Low cardiac and aerobic scope in a coastal population of sockeye salmon Oncorhynchus nerka with a short upriver migration.

PubMed

Eliason, E J; Wilson, S M; Farrell, A P; Cooke, S J; Hinch, S G

2013-06-01

This study showed that a coastal population (Harrison) of Fraser River sockeye salmon Oncorhynchus nerka had a lower aerobic and cardiac scope compared with interior populations with more challenging upriver spawning migrations, providing additional support to the idea that Fraser River O. nerka populations have adapted physiologically to their local migratory environment. © 2013 The Authors. Journal of Fish Biology © 2013 The Fisheries Society of the British Isles.

A coarse-grained model to study calcium activation of the cardiac thin filament

NASA Astrophysics Data System (ADS)

Zhang, Jing; Schwartz, Steven

2015-03-01

Familial hypertrophic cardiomyopathy (FHC) is one of the most common heart disease caused by genetic mutations. Cardiac muscle contraction and relaxation involve regulation of crossbridge binding to the cardiac thin filament, which regulates actomyosin interactions through calcium-dependent alterations in the dynamics of cardiac troponin (cTn) and tropomyosin (Tm). An atomistic model of cTn complex interacting with Tm has been studied by our group. A more realistic model requires the inclusion of the dynamics of actin filament, which is almost 6 times larger than cTn and Tm in terms of atom numbers, and extensive sampling of the model becomes very resource-demanding. By using physics-based protein united-residue force field, we introduce a coarse-grained model to study the calcium activation of the thin filament resulting from cTn's allosteric regulation of Tm dynamics on actin. The time scale is much longer than that of all-atom molecular dynamics simulation because of the reduction of the degrees of freedom. The coarse-grained model is a good template for studying cardiac thin filament mutations that cause FHC, and reduces the cost of computational resources.

Tolerance to LSD and DOB induced shaking behaviour: differential adaptations of frontocortical 5-HT(2A) and glutamate receptor binding sites.

PubMed

Buchborn, Tobias; Schröder, Helmut; Dieterich, Daniela C; Grecksch, Gisela; Höllt, Volker

2015-03-15

Serotonergic hallucinogens, such as lysergic acid diethylamide (LSD) and dimethoxy-bromoamphetamine (DOB), provoke stereotype-like shaking behaviour in rodents, which is hypothesised to engage frontocortical glutamate receptor activation secondary to serotonin2A (5-HT2A) related glutamate release. Challenging this hypothesis, we here investigate whether tolerance to LSD and DOB correlates with frontocortical adaptations of 5-HT2A and/or overall-glutamate binding sites. LSD and DOB (0.025 and 0.25 mg/kg, i.p.) induce a ketanserin-sensitive (0.5 mg/kg, i.p., 30-min pretreatment) increase in shaking behaviour (including head twitches and wet dog shakes), which with repeated application (7× in 4 ds) is undermined by tolerance. Tolerance to DOB, as indexed by DOB-sensitive [(3)H]spiroperidol and DOB induced [(35)S]GTP-gamma-S binding, is accompanied by a frontocortical decrease in 5-HT2A binding sites and 5-HT2 signalling, respectively; glutamate-sensitive [(3)H]glutamate binding sites, in contrast, remain unchanged. As to LSD, 5-HT2 signalling and 5-HT2A binding, respectively, are not or only marginally affected, yet [(3)H]glutamate binding is significantly decreased. Correlation analysis interrelates tolerance to DOB to the reduced 5-HT2A (r=.80) as well as the unchanged [(3)H]glutamate binding sites (r=.84); tolerance to LSD, as opposed, shares variance with the reduction in [(3)H]glutamate binding sites only (r=.86). Given that DOB and LSD both induce tolerance, one correlating with 5-HT2A, the other with glutamate receptor adaptations, it might be inferred that tolerance can arise at either level. That is, if a hallucinogen (like LSD in our study) fails to induce 5-HT2A (down-)regulation, glutamate receptors (activated postsynaptic to 5-HT2A related glutamate release) might instead adapt and thus prevent further overstimulation of the cortex. Copyright © 2014 Elsevier B.V. All rights reserved.

Iron-chelating effect of silymarin in patients with β-thalassemia major: A crossover randomised control trial.

PubMed

Darvishi-Khezri, Hadi; Salehifar, Ebrahim; Kosaryan, Mehrnoush; Karami, Hossein; Mahdavi, Mohammadreza; Alipour, Abbas; Aliasgharian, Aily

2018-03-01

This study aimed to determine the potential iron-chelating effects of silymarin in patients with β-thalassemia major receiving standard iron-chelation therapy. We evaluated whether addition of silymarin to standard iron-chelation therapy could improve iron burden markers and liver and cardiac function in these patients, via a placebo-controlled, crossover clinical study. Silymarin (140 mg) or placebo were administered thrice daily to all patients (n = 82) for 12 weeks, and after a 2-week washout period, patients were crossed over to the other groups. Silymarin efficacy was assessed by measuring serum iron level, ferritin level, total iron-binding capacity and liver and cardiac function on magnetic resonance imaging. Silymarin treatment resulted in a negative change in the serum iron and ferritin levels and a positive change in the total iron-binding capacity levels (treatment effect, p < .001, p = .06, and p = .05, respectively). Silymarin treatment led to positive changes in cardiac and liver function in both treatment sequences of study; however, this was not statistically significant. There was a negative change in liver iron concentration in both treatment sequences (treatment effect, p = .02). In conclusion, combined iron-chelation and silymarin therapy was effective for improving the iron-burden status in patients with β-thalassemia major. Copyright © 2017 John Wiley & Sons, Ltd.

Kinetic Studies of Calcium-Induced Calcium Release in Cardiac Sarcoplasmic Reticulum Vesicles

PubMed Central

Sánchez, Gina; Hidalgo, Cecilia; Donoso, Paulina

2003-01-01

Fast Ca2+ release kinetics were measured in cardiac sarcoplasmic reticulum vesicles actively loaded with Ca2+. Release was induced in solutions containing 1.2 mM free ATP and variable free [Ca2+] and [Mg2+]. Release rate constants (k) were 10-fold higher at pCa 6 than at pCa 5 whereas Ryanodine binding was highest at pCa ≤5. These results suggest that channels respond differently when exposed to sudden [Ca2+] changes than when exposed to Ca2+ for longer periods. Vesicles with severalfold different luminal calcium contents exhibited double exponential release kinetics at pCa 6, suggesting that channels undergo time-dependent activity changes. Addition of Mg2+ produced a marked inhibition of release kinetics at pCa 6 (K0.5 = 63 μM) but not at pCa 5. Coexistence of calcium activation and inhibition sites with equally fast binding kinetics is proposed to explain this behavior. Thimerosal activated release kinetics at pCa 5 at all [Mg2+] tested and increased at pCa 6 the K0.5 for Mg2+ inhibition, from 63 μM to 136 μM. We discuss the possible relevance of these results, which suggest release through RyR2 channels is subject to fast regulation by Ca2+ and Mg2+ followed by time-dependent regulation, to the physiological mechanisms of cardiac channel opening and closing. PMID:12668440

Unexpectedly low mutation rates in beta-myosin heavy chain and cardiac myosin binding protein genes in Italian patients with hypertrophic cardiomyopathy.

PubMed

Roncarati, Roberta; Latronico, Michael V G; Musumeci, Beatrice; Aurino, Stefania; Torella, Annalaura; Bang, Marie-Louise; Jotti, Gloria Saccani; Puca, Annibale A; Volpe, Massimo; Nigro, Vincenzo; Autore, Camillo; Condorelli, Gianluigi

2011-11-01

Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiac disease. Fourteen sarcomeric and sarcomere-related genes have been implicated in HCM etiology, those encoding β-myosin heavy chain (MYH7) and cardiac myosin binding protein C (MYBPC3) reported as the most frequently mutated: in fact, these account for around 50% of all cases related to sarcomeric gene mutations, which are collectively responsible for approximately 70% of all HCM cases. Here, we used denaturing high-performance liquid chromatography followed by bidirectional sequencing to screen the coding regions of MYH7 and MYBPC3 in a cohort (n = 125) of Italian patients presenting with HCM. We found 6 MHY7 mutations in 9/125 patients and 18 MYBPC3 mutations in 19/125 patients. Of the three novel MYH7 mutations found, two were missense, and one was a silent mutation; of the eight novel MYBPC3 mutations, one was a substitution, three were stop codons, and four were missense mutations. Thus, our cohort of Italian HCM patients did not harbor the high frequency of mutations usually found in MYH7 and MYBPC3. This finding, coupled to the clinical diversity of our cohort, emphasizes the complexity of HCM and the need for more inclusive investigative approaches in order to fully understand the pathogenesis of this disease. Copyright © 2011 Wiley-Liss, Inc.

Pattern analysis uncovers a chronic ethanol-induced disruption of the switch-like dynamics of C/EBP-β and C/EBP-α genome-wide binding during liver regeneration

PubMed Central

Kuttippurathu, Lakshmi; Patra, Biswanath; Cook, Daniel; Hoek, Jan B.

2017-01-01

Chronic ethanol intake impairs liver regeneration through a system-wide alteration in the regulatory networks driving the response to injury. Our study focused on the initial phase of response to 2/3rd partial hepatectomy (PHx) to investigate how adaptation to chronic ethanol intake affects the genome-wide binding profiles of the transcription factors C/EBP-β and C/EBP-α. These factors participate in complementary and often opposing functions for maintaining cellular differentiation, regulating metabolism, and governing cell growth during liver regeneration. We analyzed ChIP-seq data with a comparative pattern count (COMPACT) analysis, which exhaustively enumerates temporal patterns of discretized binding profiles to identify dominant as well as subtle patterns that may not be apparent from conventional clustering analyses. We found that adaptation to chronic ethanol intake significantly alters the genome-wide binding profile of C/EBP-β and C/EBP-α before and following PHx. A subset of these ethanol-induced changes include C/EBP-β binding to promoters of genes involved in the profibrogenic transforming growth factor-β pathway, and both C/EBP-β and C/EBP-α binding to promoters of genes involved in the cell cycle, apoptosis, homeostasis, and metabolic processes. The shift in C/EBP binding loci, coupled with an ethanol-induced increase in C/EBP-β binding at 6 h post-resection, indicates that ethanol adaptation may change both the amount and nature of C/EBP binding postresection. Taken together, our results suggest that chronic ethanol consumption leads to a spatially and temporally reorganized activity at many genomic loci, resulting in a shift in the dynamic balance and coordination of cellular processes underlying regenerative response. PMID:27815535

Eccentric and concentric cardiac hypertrophy induced by exercise training: microRNAs and molecular determinants.

PubMed

Fernandes, T; Soci, U P R; Oliveira, E M

2011-09-01

Among the molecular, biochemical and cellular processes that orchestrate the development of the different phenotypes of cardiac hypertrophy in response to physiological stimuli or pathological insults, the specific contribution of exercise training has recently become appreciated. Physiological cardiac hypertrophy involves complex cardiac remodeling that occurs as an adaptive response to static or dynamic chronic exercise, but the stimuli and molecular mechanisms underlying transduction of the hemodynamic overload into myocardial growth are poorly understood. This review summarizes the physiological stimuli that induce concentric and eccentric physiological hypertrophy, and discusses the molecular mechanisms, sarcomeric organization, and signaling pathway involved, also showing that the cardiac markers of pathological hypertrophy (atrial natriuretic factor, β-myosin heavy chain and α-skeletal actin) are not increased. There is no fibrosis and no cardiac dysfunction in eccentric or concentric hypertrophy induced by exercise training. Therefore, the renin-angiotensin system has been implicated as one of the regulatory mechanisms for the control of cardiac function and structure. Here, we show that the angiotensin II type 1 (AT1) receptor is locally activated in pathological and physiological cardiac hypertrophy, although with exercise training it can be stimulated independently of the involvement of angiotensin II. Recently, microRNAs (miRs) have been investigated as a possible therapeutic approach since they regulate the translation of the target mRNAs involved in cardiac hypertrophy; however, miRs in relation to physiological hypertrophy have not been extensively investigated. We summarize here profiling studies that have examined miRs in pathological and physiological cardiac hypertrophy. An understanding of physiological cardiac remodeling may provide a strategy to improve ventricular function in cardiac dysfunction.

A strategy for management of intraoperative Addisonian crisis during coronary artery bypass grafting.

PubMed

D'Silva, Celma; Watson, Dale; Ngaage, Dumbor

2012-04-01

Patients with Addison's disease undergoing cardiac surgery are at risk of developing a crisis. There is no consensus on the preoperative and intraoperative management of this group of patients undergoing cardiac surgery so the recommendations for non-cardiac patients are often used. The consensus statement from the international task force of the American College of Critical Care medicine recommends 100 mg of intravenous hydrocortisone for patients with adrenal insufficiency in septic shock, but in patients undergoing surgery, especially with extracorporeal circulation, the dosage may even be higher. We report our management of a patient with well-controlled adrenal insufficiency for 30 years who developed intraoperative Addisonian crisis despite the recommended preoperative corticosteroid supplementation. The importance of adequate corticosteroid supplementation for cardiac surgery patients, adapting the surgical strategy to allow for optimal management of potential complications and close monitoring with heightened awareness are discussed.

Sequential Ligand-Dependent Notch Signaling Activation Regulates Valve Primordium Formation and Morphogenesis.

PubMed

MacGrogan, Donal; D'Amato, Gaetano; Travisano, Stanislao; Martinez-Poveda, Beatriz; Luxán, Guillermo; Del Monte-Nieto, Gonzalo; Papoutsi, Tania; Sbroggio, Mauro; Bou, Vanesa; Gomez-Del Arco, Pablo; Gómez, Manuel Jose; Zhou, Bin; Redondo, Juan Miguel; Jiménez-Borreguero, Luis J; de la Pompa, José Luis

2016-05-13

The Notch signaling pathway is crucial for primitive cardiac valve formation by epithelial-mesenchymal transition, and NOTCH1 mutations cause bicuspid aortic valve; however, the temporal requirement for the various Notch ligands and receptors during valve ontogeny is poorly understood. The aim of this study is to determine the functional specificity of Notch in valve development. Using cardiac-specific conditional targeted mutant mice, we find that endothelial/endocardial deletion of Mib1-Dll4-Notch1 signaling, possibly favored by Manic-Fringe, is specifically required for cardiac epithelial-mesenchymal transition. Mice lacking endocardial Jag1, Notch1, or RBPJ displayed enlarged valve cusps, bicuspid aortic valve, and septal defects, indicating that endocardial Jag1 to Notch1 signaling is required for post-epithelial-mesenchymal transition valvulogenesis. Valve dysmorphology was associated with increased mesenchyme proliferation, indicating that Jag1-Notch1 signaling restricts mesenchyme cell proliferation non-cell autonomously. Gene profiling revealed upregulated Bmp signaling in Jag1-mutant valves, providing a molecular basis for the hyperproliferative phenotype. Significantly, the negative regulator of mesenchyme proliferation, Hbegf, was markedly reduced in Jag1-mutant valves. Hbegf expression in embryonic endocardial cells could be readily activated through a RBPJ-binding site, identifying Hbegf as an endocardial Notch target. Accordingly, addition of soluble heparin-binding EGF-like growth factor to Jag1-mutant outflow tract explant cultures rescued the hyperproliferative phenotype. During cardiac valve formation, Dll4-Notch1 signaling leads to epithelial-mesenchymal transition and cushion formation. Jag1-Notch1 signaling subsequently restrains Bmp-mediated valve mesenchyme proliferation by sustaining Hbegf-EGF receptor signaling. Our studies identify a mechanism of signaling cross talk during valve morphogenesis involved in the origin of congenital heart defects associated with reduced NOTCH function. © 2016 American Heart Association, Inc.

MEK1 inhibits cardiac PPARα activity by direct interaction and prevents its nuclear localization.

PubMed

el Azzouzi, Hamid; Leptidis, Stefanos; Bourajjaj, Meriem; van Bilsen, Marc; da Costa Martins, Paula A; De Windt, Leon J

2012-01-01

The response of the postnatal heart to growth and stress stimuli includes activation of a network of signal transduction cascades, including the stress activated protein kinases such as p38 mitogen-activated protein kinase (MAPK), c-Jun NH2-terminal kinase (JNK) and the extracellular signal-regulated kinase (ERK1/2) pathways. In response to increased workload, the mitogen-activated protein kinase kinase (MAPKK) MEK1 has been shown to be active. Studies embarking on mitogen-activated protein kinase (MAPK) signaling cascades in the heart have indicated peroxisome-proliferators activated-receptors (PPARs) as downstream effectors that can be regulated by this signaling cascade. Despite the importance of PPARα in controlling cardiac metabolism, little is known about the relationship between MAPK signaling and cardiac PPARα signaling. Using co-immunoprecipitation and immunofluorescence approaches we show a complex formation of PPARα with MEK1 and not with ERK1/2. Binding of PPARα to MEK1 is mediated via a LXXLL motif and results in translocation from the nucleus towards the cytoplasm, hereby disabling the transcriptional activity of PPARα. Mice subjected to voluntary running-wheel exercise showed increased cardiac MEK1 activation and complex formation with PPARα, subsequently resulting in reduced PPARα activity. Inhibition of MEK1, using U0126, blunted this effect. Here we show that activation of the MEK1-ERK1/2 pathway leads to specific inhibition of PPARα transcriptional activity. Furthermore we show that this inhibitory effect is mediated by MEK1, and not by its downstream effector kinase ERK1/2, through a mechanism involving direct binding to PPARα and subsequent stimulation of PPARα export from the nucleus.

Determining the Specificity of Cascade Binding, Interference, and Primed Adaptation In Vivo in the Escherichia coli Type I-E CRISPR-Cas System.

PubMed

Cooper, Lauren A; Stringer, Anne M; Wade, Joseph T

2018-04-17

In clustered regularly interspaced short palindromic repeat (CRISPR)-Cas (CRISPR-associated) immunity systems, short CRISPR RNAs (crRNAs) are bound by Cas proteins, and these complexes target invading nucleic acid molecules for degradation in a process known as interference. In type I CRISPR-Cas systems, the Cas protein complex that binds DNA is known as Cascade. Association of Cascade with target DNA can also lead to acquisition of new immunity elements in a process known as primed adaptation. Here, we assess the specificity determinants for Cascade-DNA interaction, interference, and primed adaptation in vivo , for the type I-E system of Escherichia coli Remarkably, as few as 5 bp of crRNA-DNA are sufficient for association of Cascade with a DNA target. Consequently, a single crRNA promotes Cascade association with numerous off-target sites, and the endogenous E. coli crRNAs direct Cascade binding to >100 chromosomal sites. In contrast to the low specificity of Cascade-DNA interactions, >18 bp are required for both interference and primed adaptation. Hence, Cascade binding to suboptimal, off-target sites is inert. Our data support a model in which the initial Cascade association with DNA targets requires only limited sequence complementarity at the crRNA 5' end whereas recruitment and/or activation of the Cas3 nuclease, a prerequisite for interference and primed adaptation, requires extensive base pairing. IMPORTANCE Many bacterial and archaeal species encode CRISPR-Cas immunity systems that protect against invasion by foreign DNA. In the Escherichia coli CRISPR-Cas system, a protein complex, Cascade, binds 61-nucleotide (nt) CRISPR RNAs (crRNAs). The Cascade complex is directed to invading DNA molecules through base pairing between the crRNA and target DNA. This leads to recruitment of the Cas3 nuclease, which destroys the invading DNA molecule and promotes acquisition of new immunity elements. We made the first in vivo measurements of Cascade binding to DNA targets. Thus, we show that Cascade binding to DNA is highly promiscuous; endogenous E. coli crRNAs can direct Cascade binding to >100 chromosomal locations. In contrast, we show that targeted degradation and acquisition of new immunity elements require highly specific association of Cascade with DNA, limiting CRISPR-Cas function to the appropriate targets. Copyright © 2018 Cooper et al.

Adaptive servo-ventilation for central sleep apnoea in systolic heart failure: results of the major substudy of SERVE-HF.

PubMed

Cowie, Martin R; Woehrle, Holger; Wegscheider, Karl; Vettorazzi, Eik; Lezius, Susanne; Koenig, Wolfgang; Weidemann, Frank; Smith, Gillian; Angermann, Christiane; d'Ortho, Marie-Pia; Erdmann, Erland; Levy, Patrick; Simonds, Anita K; Somers, Virend K; Zannad, Faiez; Teschler, Helmut

2018-03-01

The SERVE-HF trial investigated the impact of treating central sleep apnoea (CSA) with adaptive servo-ventilation (ASV) in patients with systolic heart failure. A preplanned substudy was conducted to provide insight into mechanistic changes underlying the observed effects of ASV, including assessment of changes in left ventricular function, ventricular remodelling, and cardiac, renal and inflammatory biomarkers. In a subset of the 1325 randomised patients, echocardiography, cardiac magnetic resonance imaging (cMRI) and biomarker analysis were performed at baseline, and 3 and 12 months. In secondary analyses, data for patients with baseline and 12-month values were evaluated; 312 patients participated in the substudy. The primary endpoint, change in echocardiographically determined left ventricular ejection fraction from baseline to 12 months, did not differ significantly between the ASV and the control groups. There were also no significant between-group differences for changes in left ventricular dimensions, wall thickness, diastolic function or right ventricular dimensions and ejection fraction (echocardiography), and on cMRI (in small patient numbers). Plasma N-terminal pro B-type natriuretic peptide concentration decreased in both groups, and values were similar at 12 months. There were no significant between-group differences in changes in cardiac, renal and systemic inflammation biomarkers. In patients with systolic heart failure and CSA, addition of ASV to guideline-based medical management had no statistically significant effect on cardiac structure and function, or on cardiac biomarkers, renal function and systemic inflammation over 12 months. The increased cardiovascular mortality reported in SERVE-HF may not be related to adverse remodelling or worsening heart failure. © 2017 The Authors. European Journal of Heart Failure © 2017 European Society of Cardiology.

Myosin light chain phosphorylation is critical for adaptation to cardiac stress.

PubMed

Warren, Sonisha A; Briggs, Laura E; Zeng, Huadong; Chuang, Joyce; Chang, Eileen I; Terada, Ryota; Li, Moyi; Swanson, Maurice S; Lecker, Stewart H; Willis, Monte S; Spinale, Francis G; Maupin-Furlowe, Julie; McMullen, Julie R; Moss, Richard L; Kasahara, Hideko

2012-11-27

Cardiac hypertrophy is a common response to circulatory or neurohumoral stressors as a mechanism to augment contractility. When the heart is under sustained stress, the hypertrophic response can evolve into decompensated heart failure, although the mechanism(s) underlying this transition remain largely unknown. Because phosphorylation of cardiac myosin light chain 2 (MLC2v), bound to myosin at the head-rod junction, facilitates actin-myosin interactions and enhances contractility, we hypothesized that phosphorylation of MLC2v plays a role in the adaptation of the heart to stress. We previously identified an enzyme that predominantly phosphorylates MLC2v in cardiomyocytes, cardiac myosin light-chain kinase (cMLCK), yet the role(s) played by cMLCK in regulating cardiac function in health and disease remain to be determined. We found that pressure overload induced by transaortic constriction in wild-type mice reduced phosphorylated MLC2v levels by ≈40% and cMLCK levels by ≈85%. To examine how a reduction in cMLCK and the corresponding reduction in phosphorylated MLC2v affect function, we generated Mylk3 gene-targeted mice and transgenic mice overexpressing cMLCK specifically in cardiomyocytes. Pressure overload led to severe heart failure in cMLCK knockout mice but not in mice with cMLCK overexpression in which cMLCK protein synthesis exceeded degradation. The reduction in cMLCK protein during pressure overload was attenuated by inhibition of ubiquitin-proteasome protein degradation systems. Our results suggest the novel idea that accelerated cMLCK protein turnover by the ubiquitin-proteasome system underlies the transition from compensated hypertrophy to decompensated heart failure as a result of reduced phosphorylation of MLC2v.

[Heart fatty-acid binding protein (h-FABP): a new cardiac marker].

PubMed

Servonnet, A; Delacour, H; Dehan, C; Gardet, V

2006-01-01

Heart Fatty-Acid Binding Protein (h-FABP) is a small cytosolic protein that is abundant in the heart and found at lower concentrations in muscle or in the brain. h-FABP is released into the circulation shortly after the onset of ischemia. Several studies indicate its usefulness in cardiology: exclusion of acute myocardial infarction, detection of reperfusion, prognostic value... A rapid immuno-chromatographic assay (Cardiodetect) was recently commercialized in France with a result obtainable within 15 minutes. We review the strengths and weakness of h-FABP for detecting myocardial injury.

Propagation of classical swine fever virus in vitro circumventing heparan sulfate-adaptation.

PubMed

Eymann-Häni, Rita; Leifer, Immanuel; McCullough, Kenneth C; Summerfield, Artur; Ruggli, Nicolas

2011-09-01

Amplification of natural virus isolates in permanent cell lines can result in adaptation, in particular enhanced binding to heparan sulfate (HS)-containing glycosaminoglycans present on most vertebrate cells. This has been reported for several viruses, including the pestivirus classical swine fever virus (CSFV), the causative agent of a highly contagious hemorrhagic disease in pigs. Propagation of CSFV in cell culture is essential in virus diagnostics and research. Adaptation of CSFV to HS-binding has been related to amino acid changes in the viral E(rns) glycoprotein, resulting in viruses with altered replication characteristics in vitro and in vivo. Consequently, a compound blocking the HS-containing structures on cell surfaces was employed to monitor conversion from HS-independency to HS-dependency. It was shown that the porcine PEDSV.15 cell line permitted propagation of CSFV within a limited number of passages without adaptation to HS-binding. The selection of HS-dependent CSFV mutants was also prevented by propagation of the virus in the presence of DSTP 27. The importance of these findings can be seen from the altered ratio of cell-associated to secreted virus upon acquisition of enhanced HS-binding affinity, a phenotype proposed previously to be related to virulence in the natural host. Copyright © 2011 Elsevier B.V. All rights reserved.

Reduced intrinsic heart rate is associated with reduced arrhythmic susceptibility in guinea-pig heart.

PubMed

Osadchii, Oleg E

2014-12-01

In the clinical setting, patients with slower resting heart rate are less prone to cardiovascular death compared with those with elevated heart rate. However, electrophysiological adaptations associated with reduced cardiac rhythm have not been thoroughly explored. In this study, relationships between intrinsic heart rate and arrhythmic susceptibility were examined by assessments of action potential duration (APD) rate adaptation and inducibility of repolarization alternans in sinoatrial node (SAN)-driven and atrioventricular (AV)-blocked guinea-pig hearts perfused with Langendorff apparatus. Electrocardiograms, epicardial monophasic action potentials, and effective refractory periods (ERP) were assessed in normokalemic and hypokalemic conditions. Slower basal heart rate in AV-blocked hearts was associated with prolonged ventricular repolarization during spontaneous beating, and with attenuated APD shortening at increased cardiac activation rates during dynamic pacing, when compared with SAN-driven hearts. During hypokalemic perfusion, the inducibility of repolarization alternans and tachyarrhythmia by rapid pacing was found to be lower in AV-blocked hearts. This difference was ascribed to prolonged ERP in the setting of reduced basal heart rate, which prevented ventricular capture at critically short pacing intervals required to induce arrhythmia. Reduced basal heart rate is associated with electrophysiological changes that prevent electrical instability upon an abrupt cardiac acceleration.

Alpha-1-Adrenergic Receptors in Heart Failure: The Adaptive Arm of the Cardiac Response to Chronic Catecholamine Stimulation

PubMed Central

Jensen, Brian C.; O'Connell, Timothy D.; Simpson, Paul C.

2013-01-01

Alpha-1-adrenergic receptors are G-protein coupled receptors (GPCRs) activated by catecholamines. The alpha-1A and alpha-1B subtypes are expressed in mouse and human myocardium, whereas the alpha-1D protein is found only in coronary arteries. There are far fewer alpha-1-ARs than beta-ARs in the non-failing heart, but their abundance is maintained or increased in the setting of heart failure, which is characterized by pronounced chronic elevation of catecholamines and b□eta-AR dysfunction. Decades of evidence from gain- and loss-of-function studies in isolated cardiac myocytes and numerous animal models demonstrate important adaptive functions for cardiac alpha-1-ARs, to include physiological hypertrophy, positive inotropy, ischemic preconditioning, and protection from cell death. Clinical trial data indicate that blocking alpha-1-ARs is associated with incident heart failure in patients with hypertension. Collectively, these findings suggest that alpha-1-AR activation might mitigate the well-recognized toxic effects of beta-ARs in the hyperadrenergic setting of chronic heart failure. Thus, exogenous cardioselective activation of alpha-1-ARs might represent a novel and viable approach to the treatment of heart failure. PMID:24145181

The Binding of Learning to Action in Motor Adaptation

PubMed Central

Gonzalez Castro, Luis Nicolas; Monsen, Craig Bryant; Smith, Maurice A.

2011-01-01

In motor tasks, errors between planned and actual movements generally result in adaptive changes which reduce the occurrence of similar errors in the future. It has commonly been assumed that the motor adaptation arising from an error occurring on a particular movement is specifically associated with the motion that was planned. Here we show that this is not the case. Instead, we demonstrate the binding of the adaptation arising from an error on a particular trial to the motion experienced on that same trial. The formation of this association means that future movements planned to resemble the motion experienced on a given trial benefit maximally from the adaptation arising from it. This reflects the idea that actual rather than planned motions are assigned ‘credit’ for motor errors because, in a computational sense, the maximal adaptive response would be associated with the condition credited with the error. We studied this process by examining the patterns of generalization associated with motor adaptation to novel dynamic environments during reaching arm movements in humans. We found that these patterns consistently matched those predicted by adaptation associated with the actual rather than the planned motion, with maximal generalization observed where actual motions were clustered. We followed up these findings by showing that a novel training procedure designed to leverage this newfound understanding of the binding of learning to action, can improve adaptation rates by greater than 50%. Our results provide a mechanistic framework for understanding the effects of partial assistance and error augmentation during neurologic rehabilitation, and they suggest ways to optimize their use. PMID:21731476

Clinical determinants and consequences of left ventricular hypertrophy.

PubMed

Messerli, F H

1983-09-26

The left ventricle adapts to an increased afterload such as that produced by arterial hypertension with concentric left ventricular hypertrophy. However, this adaptive process can be modified by a variety of physiologic and pathophysiologic states. Progressive aging, black race, and perhaps disorders with an increased sympathetic outflow seem to accelerate left ventricular hypertrophy. Obesity and other high cardiac output states predominantly produce dilatation of the left ventricle, and their combination with arterial hypertension results in eccentric left ventricular hypertrophy. Similarly, endurance exercise increases left ventricular volume more than wall thickness, whereas isometric exercise produces an increase in wall thickness only. The presence or absence of some physiologic and pathogenetic factors has direct implication on the assessment of what constitutes a "normal" left ventricular structure and function. Left ventricular hypertrophy has been shown to increase ventricular ectopic impulse generation and to put patients at a high risk of sudden death. Moreover, the increase in myocardial mass lowers coronary reserve and enhances cardiac oxygen requirements. Thus, the presence of left ventricular hypertrophy has to be considered as an ominous sign rather than as a benign adaptive process.

Successive contractile periods activate mitochondria at the onset of contractions in intact rat cardiac trabeculae.

PubMed

Wüst, Rob C I; Stienen, Ger J M

2018-04-01

The rate of oxidative phosphorylation depends on the contractile activity of the heart. Cardiac mitochondrial oxidative phosphorylation is determined by free ADP concentration, mitochondrial Ca 2+ accumulation, mitochondrial enzyme activities, and Krebs cycle intermediates. The purpose of the present study was to examine the factors that limit oxidative phosphorylation upon rapid changes in contractile activity in cardiac muscle. We tested the hypotheses that prior contractile performance enhances the changes in NAD(P)H and FAD concentration upon an increase in contractile activity and that this mitochondrial "priming" depends on pyruvate dehydrogenase activity. Intact rat cardiac trabeculae were electrically stimulated at 0.5 Hz for at least 30 min. Thereafter, two equal bouts at elevated stimulation frequency of 1, 2, or 3 Hz were applied for 3 min with 3 min of 0.5-Hz stimulation in between. No discernible time delay was observed in the changes in NAD(P)H and FAD fluorescence upon rapid changes in contractile activity. The amplitudes of the rapid changes in fluorescence upon an increase in stimulation frequency (the on-transients) were smaller than upon a decrease in stimulation frequency (the off-transients). A first bout in glucose-containing superfusion solution resulted, during the second bout, in an increase in the amplitudes of the on-transients, but the off-transients remained the same. No such priming effect was observed after addition of 10 mM pyruvate. These results indicate that mitochondrial priming can be observed in cardiac muscle in situ and that pyruvate dehydrogenase activity is critically involved in the mitochondrial adaptation to increases in contractile performance. NEW & NOTEWORTHY Mitochondrial respiration increases with increased cardiac contractile activity. Similar to mitochondrial "priming" in skeletal muscle, we hypothesized that cardiac mitochondrial activity is altered upon successive bouts of contractions and depends on pyruvate dehydrogenase activity. We found altered bioenergetics upon repeated contractile periods, indicative of mitochondrial priming in rat myocardium. No effect was seen when pyruvate was added to the perfusate. As such, pyruvate dehydrogenase activity is involved in the mitochondrial adaptation to increased contractile performance.

[Cardiac efficiency in patients with Cheyne-Stokes respiration as a result of heart insufficiency during long-term nasal respiratory treatment with adaptive servo ventilation (AutoSet CS)].

PubMed

Schädlich, S; Königs, I; Kalbitz, F; Blankenburg, T; Busse, H-J; Schütte, W

2004-06-01

Cheyne-Stokes respiration (CSR) is known to be an important negative predictor of outcome in patients with congestive heart failure. The goal of this study was to investigate whether the use of adaptive servo ventilation (AutoSet CS) would permit sufficient suppression of this pathological breathing pattern and improve cardiac function in longterm use over 1 year. Inclusion criteria for the study were congestive heart failure (left ventricular ejection fraction 20-50%), proven CSR with a central apnea-hypopnea index (AHI) > 15/h and stable clinical status with standard medical therapy. Patients with obstructive sleep apnea and COPD were excluded. Twenty consecutive patients (16 male) age 65.5 years (range 48-77) were followed with full blood counts, blood gas analysis, lung function tests and questionnaires for cardiopulmonary capacities (Minnesota, MRC Scale) and sleepiness (Epworth Sleepiness Scale). In addition, we performed 6-min walk distance (6MWD), echocardiography and polysomnography just before and after adjusting to adaptive servo ventilation and 3 and 12 months later. Mean usage of adaptive servo ventilation was sufficient (4.3 +/- 2.1 h/day at 12 months). No significant changes in blood gas analysis, blood counts and pulmonary function were detectable. CSR disappeared almost completely in all patients (AHI pre-study 44.3 +/- 13.4/h vs 3.4 +/- 8.0/h at 12 months; p < 0.0001). Saturation normalized steadily over the course of the study. The desaturation index decreased from 45.3 +/- 17.8/h to 5.2 +/- 11.5/h at 12 months (p < 0.0001). Mean saturation increased with the first night of sleep with adaptive servo ventilation from 92.0 +/- 2.5% to 93.0 +/- 1.6% (p < 0.05) and then to 94.1 +/- 1.9% at 3, and 94.2 +/- 1.9% at 12 months (p < 0.001). Quality of sleep was significantly improved with an increase of slow-wave sleep from 4.5 +/- 4.6% to 13.7 +/- 6.9% at 12 months (p < 0.0001). The arousal index concomitantly decreased from 29.8 +/- 17.9/h pre-study to 12.0 +/- 10.3/h at 12 months (p < 0.01). REM-sleep and sleep efficiency remained unchanged. The Epworth Sleepiness Scale showed only a trend to improvement. Cardiac function improved significantly during the course of the study. The ejection fraction increased from mean 37.1 +/- 12.5% pre-study to 41.7 +/- 8.8% at 12 months (p < 0.05). The 6-min walk distance increased from 192 +/- 110 m to 277 +/- 130 m at 12 months (p < 0.01). The MRC and Minnesota score were not significantly different pre- and post-study. We conclude that long-term respirator therapy with adaptive servo ventilation has sufficiently suppressed CSR and improved cardiac function in patients with congestive heart failure. Thus, safety and feasibility of this respirator therapy could be demonstrated. However, due to methodological reasons (no control group, no randomization) a direct effect on cardiac function could not be confirmed.

Digoxin Induces Cardiac Hypertrophy Without Negative Effects on Cardiac Function and Physical Performance in Trained Normotensive Rats.

PubMed

Neves, Claodete Hasselstrom; Tibana, Ramires Alsamir; Prestes, Jonato; Voltarelli, Fabricio Azevedo; Aguiar, Andreo Fernando; Ferreira Mota, Gustavo Augusto; de Sousa, Sergio Luiz Borges; Leopoldo, Andre Soares; Leopoldo, Ana Paula Lima; Mueller, Andre; Aguiar, Danilo Henrique; Navalta, James Wilfred; Sugizaki, Mario Mateus

2017-04-01

Cardiotonic drugs and exercise training promote cardiac inotropic effects, which may affect training-induced cardiac adaptations. This study investigated the effects of long-term administration of digoxin on heart structure and function, and physical performance of rats submitted to high-intensity interval training (HIIT). Male Wistar rats, 60 days old, were divided into control (C), digoxin (DIGO), trained (T), and trained with digoxin (TDIGO). Digoxin was administered by gavage (30 µg/kg/day) for 75 days. The HIIT program consisted of treadmill running 60 min/day (8 min at 80% of the maximum speed (MS) and 2 min at 20% of the MS), 5 days per week during 60 days. The main cardiac parameters were evaluated by echocardiograph and cardiomyocyte area was determined by histology. There were no group x time effects of digoxin, HIIT or interactions (digoxin and HIIT) on functional echocardiographic parameters (heart rate; ejection fraction) or in the maximum exercise test. There was a group x time interaction, as evidenced by observed cardiac hypertrophy in the TDIGO group evaluated by ratio of left ventricle weight to body weight (p<0.002) and cardiomyocyte area (p<0.000002). Long-term administration of digoxin promoted cardiac hypertrophy without affecting cardiac function and physical performance in rats submitted to HIIT. © Georg Thieme Verlag KG Stuttgart · New York.

Serum cortisol as a useful predictor of cardiac events in patients with chronic heart failure: the impact of oxidative stress.

PubMed

Yamaji, Masayuki; Tsutamoto, Takayoshi; Kawahara, Chiho; Nishiyama, Keizo; Yamamoto, Takashi; Fujii, Masanori; Horie, Minoru

2009-11-01

The pathophysiological role of cortisol, which binds to the mineralocorticoid receptor with an affinity equal to that of aldosterone (ALD), may be influenced by oxidative stress in patients with chronic heart failure. We evaluated cardiac event prediction using cortisol levels in chronic heart failure, in comparison with ALD, adrenocorticotropic hormone, and brain natriuretic peptide (BNP), and the impact of oxidative stress. We measured the plasma levels of biomarkers such as BNP, ALD, adrenocorticotropic hormone, serum cortisol, and oxidized low-density lipoprotein (oxLDL), a biomarker of oxidative stress, in 319 consecutive symptomatic patients with chronic heart failure, and we followed these patients for a mean period of 33 months. During the follow-up period, 29 patients had cardiac events (death or hospitalization). Plasma levels of BNP, ALD, adrenocorticotropic hormone, oxLDL, and serum cortisol (16.8+/-1.8 microg/dL versus 12.4+/-0.3 microg/dL, P=0.01) were significantly higher in patients with cardiac events than in those without cardiac events. On stepwise multivariate analyses, high levels of BNP (P=0.0003), renin (P=0.002), cortisol (P=0.02), and oxLDL (P=0.002) were independent predictors of cardiac events, but ALD and adrenocorticotropic hormone levels were not. In patients with serum cortisol > or =12.5 microg/dL, the hazard ratio of cardiac events in patients with oxLDL > or =12 U/mL was 3.5 compared with that in patients with oxLDL <12 U/mL (P=0.008). These findings indicate that serum cortisol levels were a complementary and incremental cardiac event risk predictor in combination with BNP in patients with chronic heart failure and that cardiac event prediction based on cortisol levels was influenced by oxidative stress.

Interferon Regulatory Factor 7 Functions as a Novel Negative Regulator of Pathological Cardiac Hypertrophy

PubMed Central

Jiang, Ding-Sheng; Liu, Yu; Zhou, Heng; Zhang, Yan; Zhang, Xiao-Dong; Zhang, Xiao-Fei; Chen, Ke; Gao, Lu; Peng, Juan; Gong, Hui; Chen, Yingjie; Yang, Qinglin; Liu, Peter P.; Fan, Guo-Chang; Zou, Yunzeng; Li, Hongliang

2017-01-01

Cardiac hypertrophy is a complex pathological process that involves multiple factors including inflammation and apoptosis. Interferon regulatory factor 7 (IRF7) is a multifunctional regulator that participates in immune regulation, cell differentiation, apoptosis, and oncogenesis. However, the role of IRF7 in cardiac hypertrophy remains unclear. We performed aortic banding in cardiac-specific IRF7 transgenic mice, IRF7 knockout mice, and the wild-type littermates of these mice. Our results demonstrated that IRF7 was downregulated in aortic banding–induced animal hearts and cardiomyocytes that had been treated with angiotensin II or phenylephrine for 48 hours. Accordingly, heart-specific overexpression of IRF7 significantly attenuated pressure overload–induced cardiac hypertrophy, fibrosis, and dysfunction, whereas loss of IRF7 led to opposite effects. Moreover, IRF7 protected against angiotensin II–induced cardiomyocyte hypertrophy in vitro. Mechanistically, we identified that IRF7-dependent cardioprotection was mediated through IRF7 binding to inhibitor of κB kinase-β, and subsequent nuclear factor-κB inactivation. In fact, blocking nuclear factor-κB signaling with cardiac-specific inhibitors of κBαS32A/S36A super-repressor transgene counteracted the adverse effect of IRF7 deficiency. Conversely, activation of nuclear factor-κB signaling via a cardiac-specific conditional inhibitor of κB kinase-βS177E/S181E (constitutively active) transgene negated the antihypertrophic effect of IRF7 overexpression. Our data demonstrate that IRF7 acts as a novel negative regulator of pathological cardiac hypertrophy by inhibiting nuclear factor-κB signaling and may constitute a potential therapeutic target for pathological cardiac hypertrophy. PMID:24396025

Early embryonic sensitivity to cyclophosphamide in cardiac differentiation from human embryonic stem cells.

PubMed

Zhu, Ming-Xia; Zhao, Jin-Yuan; Chen, Gui-An; Guan, Li

2011-09-01

hESCs (human embryonic stem cells) can differentiate into tissue derivatives of all three germ layers in vitro and mimic the development of the embryo in vivo. In this study, we have investigated the potential of an hESC-based assay for the detection of toxicity to cardiac differentiation in embryonic development. First of all, we developed the protocol of cardiac induction from hESCs according to our previous work and distinguished cardiac precursor cells and late mature cardiomyocytes from differentiated cells, demonstrated by the Q-PCR (quantitative real-time PCR), immunocytochemistry and flow cytometry analysis. In order to test whether CPA (cyclophosphamide) induces developmental and cellular toxicity in the human embryo, we exposed the differentiating cells from hESCs to CPA (a well-known proteratogen) at different stages. We have found that a high concentration of CPA could inhibit cardiac differentiation of hESCs. Two separate exposure intervals were used to determine the effects of CPA on cardiac precursor cells and late mature cardiomyocytes respectively. The cardiac precursor cells were sensitive to CPA in non-cytotoxic concentrations for the expression of the cardiac-specific mRNA markers Nkx2.5 (NK2 transcription factor related, locus 5), GATA-4 (GATA binding protein 4 transcription factor) and TNNT2 (troponin T type 2). Non-cytotoxic CPA concentrations did not affect the mRNA markers' expression in late mature cardiomyocytes, indicating that cardiac precursors were more sensitive to CPA than late cardiomyocytes in cardiogenesis. We set up the in vitro developmental toxicity test model so as to reduce the number of test animals and expenses without compromising the safety of consumers and patients. Furthermore, such in vitro methods may be possibly suited to test a large number of chemicals than the classical employed in vivo tests.

Control of early cardiac-specific transcription of Nkx2-5 by a GATA-dependent enhancer.

PubMed

Lien, C L; Wu, C; Mercer, B; Webb, R; Richardson, J A; Olson, E N

1999-01-01

The homeobox gene Nkx2-5 is the earliest known marker of the cardiac lineage in vertebrate embryos. Nkx2-5 expression is first detected in mesodermal cells specified to form heart at embryonic day 7.5 in the mouse and expression is maintained throughout the developing and adult heart. In addition to the heart, Nkx2-5 is transiently expressed in the developing pharynx, thyroid and stomach. To investigate the mechanisms that initiate cardiac transcription during embryogenesis, we analyzed the Nkx2-5 upstream region for regulatory elements sufficient to direct expression of a lacZ transgene in the developing heart of transgenic mice. We describe a cardiac enhancer, located about 9 kilobases upstream of the Nkx2-5 gene, that fully recapitulates the expression pattern of the endogenous gene in cardiogenic precursor cells from the onset of cardiac lineage specification and throughout the linear and looping heart tube. Thereafter, as the atrial and ventricular chambers become demarcated, enhancer activity becomes restricted to the developing right ventricle. Transcription of Nkx2-5 in pharynx, thyroid and stomach is controlled by regulatory elements separable from the cardiac enhancer. This distal cardiac enhancer contains a high-affinity binding site for the cardiac-restricted zinc finger transcription factor GATA4 that is essential for transcriptional activity. These results reveal a novel GATA-dependent mechanism for activation of Nkx2-5 transcription in the developing heart and indicate that regulation of Nkx2-5 is controlled in a modular manner, with multiple regulatory regions responding to distinct transcriptional networks in different compartments of the developing heart.

Determining the Specificity of Cascade Binding, Interference, and Primed Adaptation In Vivo in the Escherichia coli Type I-E CRISPR-Cas System

PubMed Central

Cooper, Lauren A.; Stringer, Anne M.

2018-01-01

ABSTRACT In clustered regularly interspaced short palindromic repeat (CRISPR)-Cas (CRISPR-associated) immunity systems, short CRISPR RNAs (crRNAs) are bound by Cas proteins, and these complexes target invading nucleic acid molecules for degradation in a process known as interference. In type I CRISPR-Cas systems, the Cas protein complex that binds DNA is known as Cascade. Association of Cascade with target DNA can also lead to acquisition of new immunity elements in a process known as primed adaptation. Here, we assess the specificity determinants for Cascade-DNA interaction, interference, and primed adaptation in vivo, for the type I-E system of Escherichia coli. Remarkably, as few as 5 bp of crRNA-DNA are sufficient for association of Cascade with a DNA target. Consequently, a single crRNA promotes Cascade association with numerous off-target sites, and the endogenous E. coli crRNAs direct Cascade binding to >100 chromosomal sites. In contrast to the low specificity of Cascade-DNA interactions, >18 bp are required for both interference and primed adaptation. Hence, Cascade binding to suboptimal, off-target sites is inert. Our data support a model in which the initial Cascade association with DNA targets requires only limited sequence complementarity at the crRNA 5′ end whereas recruitment and/or activation of the Cas3 nuclease, a prerequisite for interference and primed adaptation, requires extensive base pairing. PMID:29666291

Defective calmodulin binding to the cardiac ryanodine receptor plays a key role in CPVT-associated channel dysfunction

PubMed Central

Xu, Xiaojuan; Yano, Masafumi; Uchinoumi, Hitoshi; Hino, Akihiro; Suetomi, Takeshi; Ono, Makoto; Tateishi, Hiroki; Oda, Tetsuro; Okuda, Shinichi; Doi, Masahiro; Kobayashi, Shigeki; Yamamoto, Takeshi; Ikeda, Yasuhiro; Ikemoto, Noriaki; Matsuzaki, Masunori

2010-01-01

Calmodulin (CaM), one of the accessory proteins of the cardiac ryanodine receptor (RyR2), is known to play a significant role in the channel regulation of the RyR2. However, the possible involvement of calmodulin in the pathogenic process of catecholaminergic polymorphic ventricular tachycardia (CPVT) has not been investigated. In this study, we investigated the state of RyR2-bound CaM and channel dysfunctions using a knock-in (KI) mouse model with CPVT-linked RyR2 mutation (R2474S). Without added effectors, the affinity of CaM binding to the RyR2 was indistinguishable between KI and WT hearts. In response to cAMP (1 μmol/L), the RyR2 phosphorylation at Ser2808 increased in both WT and KI hearts to the same extent. However, cAMP caused a significant decrease of the CaM binding affinity in KI hearts, but the affinity was unchanged in WT. Dantrolene restored a normal level of CaM-binding affinity in the cAMP-treated KI hearts, suggesting that defective inter-domain interaction between the N-terminal domain and the central domain of the RyR2 (the target of therapeutic effect of dantrolene) is involved in the cAMP-induced reduction of the CaM binding affinity. In saponin-permeabilized cardiomyocytes, the addition of cAMP increased the frequency of spontaneous Ca2+ sparks to a significantly larger extent in KI cardiomyocytes than in WT cardiomyocytes, whereas the addition of a high concentration of CaM attenuated the aberrant increase of Ca2+ sparks. In conclusion, CPVT mutation causes defective inter-domain interaction, significant reduction in the ability of CaM binding to the RyR2, spontaneous Ca2+ leak, and then lethal arrhythmia. PMID:20226167

Sulfonylureas suppress the stimulatory action of Mg-nucleotides on Kir6.2/SUR1 but not Kir6.2/SUR2A KATP channels: a mechanistic study.

PubMed

Proks, Peter; de Wet, Heidi; Ashcroft, Frances M

2014-11-01

Sulfonylureas, which stimulate insulin secretion from pancreatic β-cells, are widely used to treat both type 2 diabetes and neonatal diabetes. These drugs mediate their effects by binding to the sulfonylurea receptor subunit (SUR) of the ATP-sensitive K(+) (KATP) channel and inducing channel closure. The mechanism of channel inhibition is unusually complex. First, sulfonylureas act as partial antagonists of channel activity, and second, their effect is modulated by MgADP. We analyzed the molecular basis of the interactions between the sulfonylurea gliclazide and Mg-nucleotides on β-cell and cardiac types of KATP channel (Kir6.2/SUR1 and Kir6.2/SUR2A, respectively) heterologously expressed in Xenopus laevis oocytes. The SUR2A-Y1206S mutation was used to confer gliclazide sensitivity on SUR2A. We found that both MgATP and MgADP increased gliclazide inhibition of Kir6.2/SUR1 channels and reduced inhibition of Kir6.2/SUR2A-Y1206S. The latter effect can be attributed to stabilization of the cardiac channel open state by Mg-nucleotides. Using a Kir6.2 mutation that renders the KATP channel insensitive to nucleotide inhibition (Kir6.2-G334D), we showed that gliclazide abolishes the stimulatory effects of MgADP and MgATP on β-cell KATP channels. Detailed analysis suggests that the drug both reduces nucleotide binding to SUR1 and impairs the efficacy with which nucleotide binding is translated into pore opening. Mutation of one (or both) of the Walker A lysines in the catalytic site of the nucleotide-binding domains of SUR1 may have a similar effect to gliclazide on MgADP binding and transduction, but it does not appear to impair MgATP binding. Our results have implications for the therapeutic use of sulfonylureas. © 2014 Proks et al.

Association of Circulating Adipokines With Echocardiographic Measures of Cardiac Structure and Function in a Community-Based Cohort.

PubMed

von Jeinsen, Beatrice; Short, Meghan I; Xanthakis, Vanessa; Carneiro, Herman; Cheng, Susan; Mitchell, Gary F; Vasan, Ramachandran S

2018-06-21

Adipokines mediate cardiometabolic risk associated with obesity but their role in the pathogenesis of obesity-associated heart failure remains uncertain. We investigated the associations between circulating adipokine concentrations and echocardiographic measures in a community-based sample. We evaluated 3514 Framingham Heart Study participants (mean age 40 years, 53.8% women) who underwent routine echocardiography and had select circulating adipokines measured, ie, leptin, soluble leptin receptor, fatty acid-binding protein 4, retinol-binding protein 4, fetuin-A, and adiponectin. We used multivariable linear regression, adjusting for known correlates (including weight), to relate adipokine concentrations (independent variables) to the following echocardiographic measures (dependent variables): left ventricular mass index, left atrial diameter in end systole, fractional shortening, and E/e'. In multivariable-adjusted analysis, left ventricular mass index was inversely related to circulating leptin and fatty acid-binding protein 4 concentrations but positively related to retinol-binding protein 4 and leptin receptor levels ( P ≤0.002 for all). Left atrial end-systolic dimension was inversely related to leptin but positively related to retinol-binding protein 4 concentrations ( P ≤0.0001). E/e' was inversely related to leptin receptor levels ( P =0.0002). We observed effect modification by body weight for select associations (leptin receptor and fatty acid-binding protein 4 with left ventricular mass index, and leptin with left atrial diameter in end systole; P <0.05 for interactions). Fractional shortening was not associated with any of the adipokines. No echocardiographic trait was associated with fetuin-A or adiponectin concentrations. In our cross-sectional study of a large, young to middle-aged, relatively healthy community-based sample, key indices of subclinical cardiac remodeling were associated with higher or lower circulating concentrations of prohypertrophic and antihypertrophic adipokines in a context-specific manner. These observations may offer insights into the pathogenesis of the cardiomyopathy of obesity. © 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

Lung Structure and the Intrinsic Challenges of Gas Exchange

PubMed Central

Hsia, Connie C.W.; Hyde, Dallas M.; Weibel, Ewald R.

2016-01-01

Structural and functional complexities of the mammalian lung evolved to meet a unique set of challenges, namely, the provision of efficient delivery of inspired air to all lung units within a confined thoracic space, to build a large gas exchange surface associated with minimal barrier thickness and a microvascular network to accommodate the entire right ventricular cardiac output while withstanding cyclic mechanical stresses that increase several folds from rest to exercise. Intricate regulatory mechanisms at every level ensure that the dynamic capacities of ventilation, perfusion, diffusion, and chemical binding to hemoglobin are commensurate with usual metabolic demands and periodic extreme needs for activity and survival. This article reviews the structural design of mammalian and human lung, its functional challenges, limitations, and potential for adaptation. We discuss (i) the evolutionary origin of alveolar lungs and its advantages and compromises, (ii) structural determinants of alveolar gas exchange, including architecture of conducting bronchovascular trees that converge in gas exchange units, (iii) the challenges of matching ventilation, perfusion, and diffusion and tissue-erythrocyte and thoracopulmonary interactions. The notion of erythrocytes as an integral component of the gas exchanger is emphasized. We further discuss the signals, sources, and limits of structural plasticity of the lung in alveolar hypoxia and following a loss of lung units, and the promise and caveats of interventions aimed at augmenting endogenous adaptive responses. Our objective is to understand how individual components are matched at multiple levels to optimize organ function in the face of physiological demands or pathological constraints. PMID:27065169

Forward Programming of Cardiac Stem Cells by Homogeneous Transduction with MYOCD plus TBX5

PubMed Central

Belian, Elisa; Noseda, Michela; Abreu Paiva, Marta S.; Leja, Thomas; Sampson, Robert; Schneider, Michael D.

2015-01-01

Adult cardiac stem cells (CSCs) express many endogenous cardiogenic transcription factors including members of the Gata, Hand, Mef2, and T-box family. Unlike its DNA-binding targets, Myocardin (Myocd)—a co-activator not only for serum response factor, but also for Gata4 and Tbx5—is not expressed in CSCs. We hypothesised that its absence was a limiting factor for reprogramming. Here, we sought to investigate the susceptibility of adult mouse Sca1+ side population CSCs to reprogramming by supplementing the triad of GATA4, MEF2C, and TBX5 (GMT), and more specifically by testing the effect of the missing co-activator, Myocd. Exogenous factors were expressed via doxycycline-inducible lentiviral vectors in various combinations. High throughput quantitative RT-PCR was used to test expression of 29 cardiac lineage markers two weeks post-induction. GMT induced more than half the analysed cardiac transcripts. However, no protein was detected for the induced sarcomeric genes Actc1, Myh6, and Myl2. Adding MYOCD to GMT affected only slightly the breadth and level of gene induction, but, importantly, triggered expression of all three proteins examined (α-cardiac actin, atrial natriuretic peptide, sarcomeric myosin heavy chains). MYOCD + TBX was the most effective pairwise combination in this system. In clonal derivatives homogenously expressing MYOCD + TBX at high levels, 93% of cardiac transcripts were up-regulated and all five proteins tested were visualized. In summary: (1) GMT induced cardiac genes in CSCs, but not cardiac proteins under the conditions used. (2) Complementing GMT with MYOCD induced cardiac protein expression, indicating a more complete cardiac differentiation program. (3) Homogeneous transduction with MYOCD + TBX5 facilitated the identification of differentiating cells and the validation of this combinatorial reprogramming strategy. Together, these results highlight the pivotal importance of MYOCD in driving CSCs toward a cardiac muscle fate. PMID:26047103

Forward Programming of Cardiac Stem Cells by Homogeneous Transduction with MYOCD plus TBX5.

PubMed

Belian, Elisa; Noseda, Michela; Abreu Paiva, Marta S; Leja, Thomas; Sampson, Robert; Schneider, Michael D

2015-01-01

Adult cardiac stem cells (CSCs) express many endogenous cardiogenic transcription factors including members of the Gata, Hand, Mef2, and T-box family. Unlike its DNA-binding targets, Myocardin (Myocd)-a co-activator not only for serum response factor, but also for Gata4 and Tbx5-is not expressed in CSCs. We hypothesised that its absence was a limiting factor for reprogramming. Here, we sought to investigate the susceptibility of adult mouse Sca1+ side population CSCs to reprogramming by supplementing the triad of GATA4, MEF2C, and TBX5 (GMT), and more specifically by testing the effect of the missing co-activator, Myocd. Exogenous factors were expressed via doxycycline-inducible lentiviral vectors in various combinations. High throughput quantitative RT-PCR was used to test expression of 29 cardiac lineage markers two weeks post-induction. GMT induced more than half the analysed cardiac transcripts. However, no protein was detected for the induced sarcomeric genes Actc1, Myh6, and Myl2. Adding MYOCD to GMT affected only slightly the breadth and level of gene induction, but, importantly, triggered expression of all three proteins examined (α-cardiac actin, atrial natriuretic peptide, sarcomeric myosin heavy chains). MYOCD + TBX was the most effective pairwise combination in this system. In clonal derivatives homogenously expressing MYOCD + TBX at high levels, 93% of cardiac transcripts were up-regulated and all five proteins tested were visualized. (1) GMT induced cardiac genes in CSCs, but not cardiac proteins under the conditions used. (2) Complementing GMT with MYOCD induced cardiac protein expression, indicating a more complete cardiac differentiation program. (3) Homogeneous transduction with MYOCD + TBX5 facilitated the identification of differentiating cells and the validation of this combinatorial reprogramming strategy. Together, these results highlight the pivotal importance of MYOCD in driving CSCs toward a cardiac muscle fate.

Nitric oxide and CaMKII: Critical steps in the cardiac contractile response To IGF-1 and swim training.

PubMed

Burgos, Juan I; Yeves, Alejandra M; Barrena, Jorge P; Portiansky, Enrique L; Vila-Petroff, Martín G; Ennis, Irene L

2017-11-01

Cardiac adaptation to endurance training includes improved contractility by a non-yet clarified mechanism. Since IGF-1 is the main mediator of the physiological response to exercise, we explored its effect on cardiac contractility and the putative involvement of nitric oxide (NO) and CaMKII in control and swim-trained mice. IGF-1 increased cardiomyocyte shortening (128.1±4.6% vs. basal; p˂0.05) and accelerated relaxation (time to 50% relengthening: 49.2±2.0% vs. basal; p˂0.05), effects abrogated by inhibition of: AKT with MK-2206, NO production with the NO synthase (NOS) inhibitor L-NAME and the specific NOS1 inhibitor nitroguanidine (NG), and CaMKII with KN-93. In agreement, an increase in NO in response to IGF-1 (133.8±2.2%) was detected and prevented by both L-NAME and NG but not KN-93, suggesting that CaMKII activation was downstream NO. In addition, we determined CaMKII activity (P-CaMKII) and phosphorylation of its target, Thr17-PLN. IGF-1, by a NO-dependent mechanism, significantly increased both (227.2±29.4% and 145.3±5.4%, respectively) while no changes in the CaMKII phosphorylation site of ryanodine receptor were evident. The improvement in contractility induced by IGF-1 was associated with increased Ca 2+ transient amplitude, rate of decay and SR content. Interestingly, this response was absent in cardiomyocytes from transgenic mice that express a CaMKII inhibitory peptide (AC3-I strain). Moreover, AC3-I mice subjected to swim training did develop physiological cardiac hypertrophy but not the contractile adaptation. Therefore, we conclude that NO-dependent CaMKII activation plays a critical role in the improvement in contractility induced by IGF-1 and exercise training. Interestingly, this pathway would not contribute to the adaptive hypertrophy. Copyright © 2017 Elsevier Ltd. All rights reserved.

Basic science behind the cardiovascular benefits of exercise.

PubMed

Wilson, Mathew G; Ellison, Georgina M; Cable, N Tim

2015-12-01

Cardiorespiratory fitness is a strong predictor of cardiovascular (CV) disease and all-cause mortality, with increases in cardiorespiratory fitness associated with corresponding decreases in CV disease risk. The effects of exercise upon the myocardium and vascular system are dependent upon the frequency, intensity and duration of the exercise itself. Following a prolonged period (≥ 6 months) of regular intensive exercise in previously untrained individuals, resting and submaximal exercising heart rates are typically 5-20 beats lower, with an increase in stroke volume of ∼ 20% and enhanced myocardial contractility. Structurally, all four heart chambers increase in volume with mild increases in wall thickness, resulting in greater cardiac mass due to increased myocardial cell size. With this in mind, the present paper aims to review the basic science behind the CV benefits of exercise. Attention will be paid to understanding (1) the relationship between exercise and cardiac remodelling; (2) the cardiac cellular and molecular adaptations in response to exercise, including the examination of molecular mechanisms of physiological cardiac growth and applying these mechanisms to identify new therapeutic targets to prevent or reverse pathological remodelling and heart failure; and (3) vascular adaptations in response to exercise. Finally, this review will briefly examine how to optimise the CV benefits of exercise by considering how much and how intense exercise should be. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Basic science behind the cardiovascular benefits of exercise.

PubMed

Wilson, Mathew G; Ellison, Georgina M; Cable, N Tim

2015-05-15

Cardiorespiratory fitness is a strong predictor of cardiovascular (CV) disease and all-cause mortality, with increases in cardiorespiratory fitness associated with corresponding decreases in CV disease risk. The effects of exercise upon the myocardium and vascular system are dependent upon the frequency, intensity and duration of the exercise itself. Following a prolonged period (≥6 months) of regular intensive exercise in previously untrained individuals, resting and submaximal exercising heart rates are typically 5-20 beats lower, with an increase in stroke volume of ∼20% and enhanced myocardial contractility. Structurally, all four heart chambers increase in volume with mild increases in wall thickness, resulting in greater cardiac mass due to increased myocardial cell size. With this in mind, the present paper aims to review the basic science behind the CV benefits of exercise. Attention will be paid to understanding (1) the relationship between exercise and cardiac remodelling; (2) the cardiac cellular and molecular adaptations in response to exercise, including the examination of molecular mechanisms of physiological cardiac growth and applying these mechanisms to identify new therapeutic targets to prevent or reverse pathological remodelling and heart failure; and (3) vascular adaptations in response to exercise. Finally, this review will briefly examine how to optimise the CV benefits of exercise by considering how much and how intense exercise should be. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Basic science behind the cardiovascular benefits of exercise.

PubMed

Wilson, Mathew G; Ellison, Georgina M; Cable, N Tim

2016-01-01

Cardiorespiratory fitness is a strong predictor of cardiovascular (CV) disease and all-cause mortality, with increases in cardiorespiratory fitness associated with corresponding decreases in CV disease risk. The effects of exercise upon the myocardium and vascular system are dependent upon the frequency, intensity and duration of the exercise itself. Following a prolonged period (≥6 months) of regular intensive exercise in previously untrained individuals, resting and submaximal exercising heart rates are typically 5-20 beats lower, with an increase in stroke volume of ∼20% and enhanced myocardial contractility. Structurally, all four heart chambers increase in volume with mild increases in wall thickness, resulting in greater cardiac mass due to increased myocardial cell size. With this in mind, the present paper aims to review the basic science behind the CV benefits of exercise. Attention will be paid to understanding (1) the relationship between exercise and cardiac remodelling; (2) the cardiac cellular and molecular adaptations in response to exercise, including the examination of molecular mechanisms of physiological cardiac growth and applying these mechanisms to identify new therapeutic targets to prevent or reverse pathological remodelling and heart failure; and (3) vascular adaptations in response to exercise. Finally, this review will briefly examine how to optimise the CV benefits of exercise by considering how much and how intense exercise should be. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

High-altitude physiology: lessons from Tibet

NASA Astrophysics Data System (ADS)

Wagner, Peter D.; Simonson, Tatum S.; Wei, Guan; Wagner, Harrieth; Wuren, Tanna; Yan, Ma; Qin, Ga; Ge, Rili

2013-05-01

Polycythemia is a universal lowlander response to altitude; healthy Andean high-altitude natives also have elevated [Hb]. While this may enhance O2 transport to tissues, studies have shown that acute isovolumic changes in [Hb] do not affect exercise capacity. Many high-altitude Tibetans have evolved sea-level values of [Hb], providing a natural opportunity to study this issue. In 21 young healthy male Tibetans with [Hb] between 15 and 23 g/dl, we measured VO2MAX and O2 transport capacity at 4200m. VO2MAX was higher when [Hb] was lower (P<0.05), enabled by both higher cardiac output and muscle O2 diffusional conductance, but neither ventilation nor the alveolar-arterial PO2 difference (AaPO2) varied with [Hb]. In contrast, Andean high altitude natives remain polycythemic with larger lungs and higher lung diffusing capacity, a smaller exercising AaPO2, and lower ventilation. The challenges now are (1) to understand the different adaptive pathways used by Andeans and Tibetans, and (2) to determine in Tibetans whether, during evolution, reduced [Hb] appeared first, causing compensatory cardiac and muscle adaptations, or if enhanced cardiac function and muscle O2 transport capacity appeared first, permitting secondary reduction in [Hb]. For (2), further research is necessary to determine the basis of enhanced cardiac function and muscle O2 transport, and identify molecular targets of evolution in heart and muscle. Putative mutations can then be timed and compared to appearance of those affecting [Hb].

Dynamics of change in rat arterial pressure under conditions of immobilization

NASA Technical Reports Server (NTRS)

Yumatov, Y. A.; Skotselyas, Y. G.; Ivanona, L. I.

1980-01-01

Emotional stress developed in immobilized rats was shown to be accompanied by changes in the regulation of arterial pressure and the frequency of cardiac contractions. A group of adapting rats displayed definite resistance to emotional stress, while a group of rats incapable of adapting to acute emotional stress died with characteristics of cardiovascular insufficiency. The mechanisms providing resistance to emotional stress in numerous conflict situations were analyzed.

Fractal mechanisms and heart rate dynamics. Long-range correlations and their breakdown with disease

NASA Technical Reports Server (NTRS)

Peng, C. K.; Havlin, S.; Hausdorff, J. M.; Mietus, J. E.; Stanley, H. E.; Goldberger, A. L.

1995-01-01

Under healthy conditions, the normal cardiac (sinus) interbeat interval fluctuates in a complex manner. Quantitative analysis using techniques adapted from statistical physics reveals the presence of long-range power-law correlations extending over thousands of heartbeats. This scale-invariant (fractal) behavior suggests that the regulatory system generating these fluctuations is operating far from equilibrium. In contrast, it is found that for subjects at high risk of sudden death (e.g., congestive heart failure patients), these long-range correlations break down. Application of fractal scaling analysis and related techniques provides new approaches to assessing cardiac risk and forecasting sudden cardiac death, as well as motivating development of novel physiologic models of systems that appear to be heterodynamic rather than homeostatic.

Mast cells regulate myofilament calcium sensitization and heart function after myocardial infarction.

PubMed

Ngkelo, Anta; Richart, Adèle; Kirk, Jonathan A; Bonnin, Philippe; Vilar, Jose; Lemitre, Mathilde; Marck, Pauline; Branchereau, Maxime; Le Gall, Sylvain; Renault, Nisa; Guerin, Coralie; Ranek, Mark J; Kervadec, Anaïs; Danelli, Luca; Gautier, Gregory; Blank, Ulrich; Launay, Pierre; Camerer, Eric; Bruneval, Patrick; Menasche, Philippe; Heymes, Christophe; Luche, Elodie; Casteilla, Louis; Cousin, Béatrice; Rodewald, Hans-Reimer; Kass, David A; Silvestre, Jean-Sébastien

2016-06-27

Acute myocardial infarction (MI) is a severe ischemic disease responsible for heart failure and sudden death. Inflammatory cells orchestrate postischemic cardiac remodeling after MI. Studies using mice with defective mast/stem cell growth factor receptor c-Kit have suggested key roles for mast cells (MCs) in postischemic cardiac remodeling. Because c-Kit mutations affect multiple cell types of both immune and nonimmune origin, we addressed the impact of MCs on cardiac function after MI, using the c-Kit-independent MC-deficient (Cpa3(Cre/+)) mice. In response to MI, MC progenitors originated primarily from white adipose tissue, infiltrated the heart, and differentiated into mature MCs. MC deficiency led to reduced postischemic cardiac function and depressed cardiomyocyte contractility caused by myofilament Ca(2+) desensitization. This effect correlated with increased protein kinase A (PKA) activity and hyperphosphorylation of its targets, troponin I and myosin-binding protein C. MC-specific tryptase was identified to regulate PKA activity in cardiomyocytes via protease-activated receptor 2 proteolysis. This work reveals a novel function for cardiac MCs modulating cardiomyocyte contractility via alteration of PKA-regulated force-Ca(2+) interactions in response to MI. Identification of this MC-cardiomyocyte cross-talk provides new insights on the cellular and molecular mechanisms regulating the cardiac contractile machinery and a novel platform for therapeutically addressable regulators. ©2016 Ngkelo et al.

Evaluation of Cardiac Toxicity Biomarkers in Rats from Different Laboratories

PubMed Central

Kim, Kyuri; Chini, Naseem; Fairchild, David G.; Engle, Steven K.; Reagan, William J.; Summers, Sandra D.; Mirsalis, Jon C.

2016-01-01

There is a great need for improved diagnostic and prognostic accuracy of potential cardiac toxicity in drug development. This study reports the evaluation of several commercially available biomarker kits by three institutions (SRI, Eli Lilly and Pfizer) for the discrimination between myocardial degeneration/necrosis and cardiac hypertrophy as well as the assessment of the inter-laboratory and inter-platform variation in results. Serum concentrations of natriuretic peptides (NT-proANP, NT-proBNP), cardiac and skeletal troponins (cTnI, cTnT, sTnI), myosin light chain 3 (Myl3) and fatty acid binding protein 3 (FABP3) were assessed in rats treated with minoxidil and isoproterenol. Minoxidil caused increased heart-to-body weight ratios and prominent elevations in NT-proANP and NT-proBNP concentrations detected at 24 hr postdose without elevation in troponins, Myl3 or FABP3 and with no abnormal histopathological findings. Isoproterenol caused ventricular leukocyte infiltration, myocyte fibrosis and necrosis with increased concentrations of the natriuretic peptides, cardiac troponins and Myl3. These results reinforce the advantages of a multi-marker strategy in elucidating the underlying cause of cardiac insult and detecting myocardial tissue damage at 24 hr post-treatment. The inter-laboratory and inter-platform comparison analyses also showed that the data obtained from different laboratories and platforms are highly correlated and reproducible, making these biomarkers widely applicable in preclinical studies. PMID:27638646

Zebrafish cardiac muscle thick filaments: isolation technique and three-dimensional structure.

PubMed

González-Solá, Maryví; Al-Khayat, Hind A; Behra, Martine; Kensler, Robert W

2014-04-15

To understand how mutations in thick filament proteins such as cardiac myosin binding protein-C or titin, cause familial hypertrophic cardiomyopathies, it is important to determine the structure of the cardiac thick filament. Techniques for the genetic manipulation of the zebrafish are well established and it has become a major model for the study of the cardiovascular system. Our goal is to develop zebrafish as an alternative system to the mammalian heart model for the study of the structure of the cardiac thick filaments and the proteins that form it. We have successfully isolated thick filaments from zebrafish cardiac muscle, using a procedure similar to those for mammalian heart, and analyzed their structure by negative-staining and electron microscopy. The isolated filaments appear well ordered with the characteristic 42.9 nm quasi-helical repeat of the myosin heads expected from x-ray diffraction. We have performed single particle image analysis on the collected electron microscopy images for the C-zone region of these filaments and obtained a three-dimensional reconstruction at 3.5 nm resolution. This reconstruction reveals structure similar to the mammalian thick filament, and demonstrates that zebrafish may provide a useful model for the study of the changes in the cardiac thick filament associated with disease processes. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Integrative Systems Models of Cardiac Excitation Contraction Coupling

PubMed Central

Greenstein, Joseph L.; Winslow, Raimond L.

2010-01-01

Excitation-contraction coupling in the cardiac myocyte is mediated by a number of highly integrated mechanisms of intracellular Ca2+ transport. The complexity and integrative nature of heart cell electrophysiology and Ca2+-cycling has led to an evolution of computational models that have played a crucial role in shaping our understanding of heart function. An important emerging theme in systems biology is that the detailed nature of local signaling events, such as those that occur in the cardiac dyad, have important consequences at higher biological scales. Multi-scale modeling techniques have revealed many mechanistic links between micro-scale events, such as Ca2+ binding to a channel protein, and macro-scale phenomena, such as excitation-contraction coupling gain. Here we review experimentally based multi-scale computational models of excitation-contraction coupling and the insights that have been gained through their application. PMID:21212390

Thymosin β4: multiple functions in protection, repair and regeneration of the mammalian heart.

PubMed

Bollini, Sveva; Riley, Paul R; Smart, Nicola

2015-01-01

Despite recent improvements in interventional medicine, cardiovascular disease still represents the major cause of morbidity worldwide, with myocardial infarction being the most common cardiac injury. This has sustained the development of several regenerative strategies based on the use of stem cells and tissue engineering approaches in order to achieve cardiac repair and regeneration by enhancing coronary neovascularization, modulating acute inflammation and supporting myocardial regeneration to provide new functional muscle. The actin monomer binding peptide, Thymosin β4 (Tβ4), has recently been described as a powerful regenerative agent with angiogenic, anti-inflammatory and cardioprotective effects on the heart and which specifically acts on its resident cardiac progenitor cells. In this review we will discuss the state of the art regarding the many roles of Tβ4 in preserving and regenerating the mammalian heart, with specific attention to its ability to activate the quiescent adult epicardium and specific subsets of epicardial progenitor cells for repair. The therapeutic potential of Tβ4 for the treatment of cardiac failure is herein evaluated alongside existing, emerging and prospective novel treatments.

HB-EGF function in cardiac valve development requires interaction with heparan sulfate proteoglycans.

PubMed

Iwamoto, Ryo; Mine, Naoki; Kawaguchi, Taichiro; Minami, Seigo; Saeki, Kazuko; Mekada, Eisuke

2010-07-01

HB-EGF, a member of the EGF family of growth factors, plays an important role in cardiac valve development by suppressing mesenchymal cell proliferation. Here, we show that HB-EGF must interact with heparan sulfate proteoglycans (HSPGs) to properly function in this process. In developing valves, HB-EGF is synthesized in endocardial cells but accumulates in the mesenchyme by interacting with HSPGs. Disrupting the interaction between HB-EGF and HSPGs in an ex vivo model of endocardial cushion explants resulted in increased mesenchymal cell proliferation. Moreover, homozygous knock-in mice (HB(Delta)(hb/)(Delta)(hb)) expressing a mutant HB-EGF that cannot bind to HSPGs developed enlarged cardiac valves with hyperproliferation of mesenchymal cells; this resulted in a phenotype that resembled that of Hbegf-null mice. Interestingly, although Hbegf-null mice had abnormal heart chambers and lung alveoli, HB(Delta)(hb/)(Delta)(hb) mice did not exhibit these defects. These results indicate that interactions with HSPGs are essential for the function of HB-EGF, especially in cardiac valve development, in which HB-EGF suppresses mesenchymal cell proliferation.

Bedside biomarkers in pediatric cardio renal injuries in emergency

PubMed Central

Singhal, Noopur; Saha, Abhijeet

2014-01-01

Point of care testing (POCT) using biomarkers in the emergency department reduces turnaround time for clinical decision making. An ideal biomarker should be accurate, reliable and easy to measure with a standard assay, non-invasive, sensitive and specific with defined cutoff values. Conventional biomarkers for renal injuries include rise in serum creatinine and fluid overload. Recently, neutrophil gelatinase associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), cystatin C, interleukin-18 (IL-18) and liver fatty acid binding protein (L-FABP) have been studied extensively for their role in acute kidney injury associated with various clinical entities. Biochemical markers of ischaemic cardiac damage commonly used are plasma creatine kinase and cardiac troponins (cTn). Clinically valuable cardiac markers for myocardial injury in research at present comprise BNP/NT-proBNP and to a lesser extent, CRP, which are independent predictors of adverse events including death and heart failure. Current status of point of care biomarkers for diagnosis and prognostication of renal and cardiac injuries in pediatric emergency care is appraised in this review. PMID:25337487

The myosin mesa and a possible unifying hypothesis for the molecular basis of human hypertrophic cardiomyopathy

PubMed Central

Spudich, James A.

2015-01-01

No matter how many times one explores the structure of the myosin molecule, there is always something new to discover. Here, I describe the myosin mesa, a structural feature of the motor domain that has the characteristics of a binding domain for another protein, possibly myosin-binding protein C (MyBP-C). Interestingly, many well-known hypertrophic cardiomyopathy (HCM) mutations lie along this surface and may affect the putative interactions proposed here. A potential unifying hypothesis for the molecular basis of human hypertrophic cardiomyopathy is discussed here. It involves increased power output of the cardiac muscle as a result of HCM mutations causing the release of inhibition by myosin binding protein C. PMID:25619247

Cardiotrophin 1 stimulates beneficial myogenic and vascular remodeling of the heart.

PubMed

Abdul-Ghani, Mohammad; Suen, Colin; Jiang, Baohua; Deng, Yupu; Weldrick, Jonathan J; Putinski, Charis; Brunette, Steve; Fernando, Pasan; Lee, Tom T; Flynn, Peter; Leenen, Frans H H; Burgon, Patrick G; Stewart, Duncan J; Megeney, Lynn A

2017-10-01

The post-natal heart adapts to stress and overload through hypertrophic growth, a process that may be pathologic or beneficial (physiologic hypertrophy). Physiologic hypertrophy improves cardiac performance in both healthy and diseased individuals, yet the mechanisms that propagate this favorable adaptation remain poorly defined. We identify the cytokine cardiotrophin 1 (CT1) as a factor capable of recapitulating the key features of physiologic growth of the heart including transient and reversible hypertrophy of the myocardium, and stimulation of cardiomyocyte-derived angiogenic signals leading to increased vascularity. The capacity of CT1 to induce physiologic hypertrophy originates from a CK2-mediated restraining of caspase activation, preventing the transition to unrestrained pathologic growth. Exogenous CT1 protein delivery attenuated pathology and restored contractile function in a severe model of right heart failure, suggesting a novel treatment option for this intractable cardiac disease.

Universal structures of normal and pathological heart rate variability.

PubMed

Gañán-Calvo, Alfonso M; Fajardo-López, Juan

2016-02-25

The circulatory system of living organisms is an autonomous mechanical system softly tuned with the respiratory system, and both developed by evolution as a response to the complex oxygen demand patterns associated with motion. Circulatory health is rooted in adaptability, which entails an inherent variability. Here, we show that a generalized N-dimensional normalized graph representing heart rate variability reveals two universal arrhythmic patterns as specific signatures of health one reflects cardiac adaptability, and the other the cardiac-respiratory rate tuning. In addition, we identify at least three universal arrhythmic profiles whose presences raise in proportional detriment of the two healthy ones in pathological conditions (myocardial infarction; heart failure; and recovery from sudden death). The presence of the identified universal arrhythmic structures together with the position of the centre of mass of the heart rate variability graph provide a unique quantitative assessment of the health-pathology gradient.

The crystal structures of the psychrophilic subtilisin S41 and the mesophilic subtilisin Sph reveal the same calcium-loaded state.

PubMed

Almog, Orna; González, Ana; Godin, Noa; de Leeuw, Marina; Mekel, Marlene J; Klein, Daniela; Braun, Sergei; Shoham, Gil; Walter, Richard L

2009-02-01

We determine and compare the crystal structure of two proteases belonging to the subtilisin superfamily: S41, a cold-adapted serine protease produced by Antarctic bacilli, at 1.4 A resolution and Sph, a mesophilic serine protease produced by Bacillus sphaericus, at 0.8 A resolution. The purpose of this comparison was to find out whether multiple calcium ion binding is a molecular factor responsible for the adaptation of S41 to extreme low temperatures. We find that these two subtilisins have the same subtilisin fold with a root mean square between the two structures of 0.54 A. The final models for S41 and Sph include a calcium-loaded state of five ions bound to each of these two subtilisin molecules. None of these calcium-binding sites correlate with the high affinity known binding site (site A) found for other subtilisins. Structural analysis of the five calcium-binding sites found in these two crystal structures indicate that three of the binding sites have two side chains of an acidic residue coordinating the calcium ion, whereas the other two binding sites have either a main-chain carbonyl, or only one acidic residue side chain coordinating the calcium ion. Thus, we conclude that three of the sites are of high affinity toward calcium ions, whereas the other two are of low affinity. Because Sph is a mesophilic subtilisin and S41 is a psychrophilic subtilisin, but both crystal structures were found to bind five calcium ions, we suggest that multiple calcium ion binding is not responsible for the adaptation of S41 to low temperatures. Copyright 2008 Wiley-Liss, Inc.

Cardiac Myosin Binding Protein C Phosphorylation Affects Cross-Bridge Cycle's Elementary Steps in a Site-Specific Manner

PubMed Central

Wang, Li; Sadayappan, Sakthivel; Kawai, Masakata

2014-01-01

Based on our recent finding that cardiac myosin binding protein C (cMyBP-C) phosphorylation affects muscle contractility in a site-specific manner, we further studied the force per cross-bridge and the kinetic constants of the elementary steps in the six-state cross-bridge model in cMyBP-C mutated transgenic mice for better understanding of the influence of cMyBP-C phosphorylation on contractile functions. Papillary muscle fibres were dissected from cMyBP-C mutated mice of ADA (Ala273-Asp282-Ala302), DAD (Asp273-Ala282-Asp302), SAS (Ser273-Ala282-Ser302), and t/t (cMyBP-C null) genotypes, and the results were compared to transgenic mice expressing wide-type (WT) cMyBP-C. Sinusoidal analyses were performed with serial concentrations of ATP, phosphate (Pi), and ADP. Both t/t and DAD mutants significantly reduced active tension, force per cross-bridge, apparent rate constant (2πc), and the rate constant of cross-bridge detachment. In contrast to the weakened ATP binding and enhanced Pi and ADP release steps in t/t mice, DAD mice showed a decreased ADP release without affecting the ATP binding and the Pi release. ADA showed decreased ADP release, and slightly increased ATP binding and cross-bridge detachment steps, whereas SAS diminished the ATP binding step and accelerated the ADP release step. t/t has the broadest effects with changes in most elementary steps of the cross-bridge cycle, DAD mimics t/t to a large extent, and ADA and SAS predominantly affect the nucleotide binding steps. We conclude that the reduced tension production in DAD and t/t is the result of reduced force per cross-bridge, instead of the less number of strongly attached cross-bridges. We further conclude that cMyBP-C is an allosteric activator of myosin to increase cross-bridge force, and its phosphorylation status modulates the force, which is regulated by variety of protein kinases. PMID:25420047

Cardiac myosin binding protein C phosphorylation affects cross-bridge cycle's elementary steps in a site-specific manner.

PubMed

Wang, Li; Sadayappan, Sakthivel; Kawai, Masakata

2014-01-01

Based on our recent finding that cardiac myosin binding protein C (cMyBP-C) phosphorylation affects muscle contractility in a site-specific manner, we further studied the force per cross-bridge and the kinetic constants of the elementary steps in the six-state cross-bridge model in cMyBP-C mutated transgenic mice for better understanding of the influence of cMyBP-C phosphorylation on contractile functions. Papillary muscle fibres were dissected from cMyBP-C mutated mice of ADA (Ala273-Asp282-Ala302), DAD (Asp273-Ala282-Asp302), SAS (Ser273-Ala282-Ser302), and t/t (cMyBP-C null) genotypes, and the results were compared to transgenic mice expressing wide-type (WT) cMyBP-C. Sinusoidal analyses were performed with serial concentrations of ATP, phosphate (Pi), and ADP. Both t/t and DAD mutants significantly reduced active tension, force per cross-bridge, apparent rate constant (2πc), and the rate constant of cross-bridge detachment. In contrast to the weakened ATP binding and enhanced Pi and ADP release steps in t/t mice, DAD mice showed a decreased ADP release without affecting the ATP binding and the Pi release. ADA showed decreased ADP release, and slightly increased ATP binding and cross-bridge detachment steps, whereas SAS diminished the ATP binding step and accelerated the ADP release step. t/t has the broadest effects with changes in most elementary steps of the cross-bridge cycle, DAD mimics t/t to a large extent, and ADA and SAS predominantly affect the nucleotide binding steps. We conclude that the reduced tension production in DAD and t/t is the result of reduced force per cross-bridge, instead of the less number of strongly attached cross-bridges. We further conclude that cMyBP-C is an allosteric activator of myosin to increase cross-bridge force, and its phosphorylation status modulates the force, which is regulated by variety of protein kinases.

Acute Modifications of Circulating Volume and Respiratory Maneuvers in the Cardiovascular Assessment of Long-Duration Crewmembers

NASA Technical Reports Server (NTRS)

Bogomolov, V. V.; Alferova, I. V.; Dulchavsky, S. A.; Garcia, K. M.; Martin, D. S.; Melton, S. L.; Sargsyan, A. E.; Hamilton, D. R.; Duncan, J. M.

2010-01-01

This U.S. - Russian project is aimed at improved assessment of cardiac and vascular parameters associated with circulating volume and its distribution in long-duration space flight. Objective responses to modified Valsalva and Mueller maneuvers were measured by cardiac and vascular ultrasound before, during, and after temporary volume redistribution by means of Braslet-M thigh occlusion cuffs (Russia). Braslet-M cuffs are custom fitted to each crewmember prior to launch on the Soyuz as a Russian countermeasure for space adaptation fluid shifts

Expression of androgen-binding protein (ABP) in human cardiac myocytes.

PubMed

Schock, H W; Herbert, Z; Sigusch, H; Figulla, H R; Jirikowski, G F; Lotze, U

2006-04-01

Cardiomyocytes are known to be androgen targets. Changing systemic steroid levels are thought to be linked to various cardiac ailments, including dilated cardiomyopathy (DCM). The mode of action of gonadal steroid hormones on the human heart is unknown to date. In the present study, we used high-resolution immunocytochemistry on semithin sections (1 microm thick), IN SITU hybridization, and mass spectrometry to investigate the expression of androgen-binding protein (ABP) in human myocardial biopsies taken from male patients with DCM. We observed distinct cytoplasmic ABP immunoreactivity in a fraction of the myocytes. IN SITU hybridization with synthetic oligonucleotide probes revealed specific hybridization signals in these cells. A portion of the ABP-positive cells contained immunostaining for androgen receptor. With SELDI TOF mass spectrometry of affinity purified tissue extracts of human myocardium, we confirmed the presence of a 50 kDa protein similar to ABP. Our observations provide evidence of an intrinsic expression of ABP in human heart. ABP may be secreted from myocytes in a paracrine manner perhaps to influence the bioavailabity of gonadal steroids in myocardium.

Translation, Cross-cultural Adaptation and Psychometric Validation of the Korean-Language Cardiac Rehabilitation Barriers Scale (CRBS-K).

PubMed

Baek, Sora; Park, Hee-Won; Lee, Yookyung; Grace, Sherry L; Kim, Won-Seok

2017-10-01

To perform a translation and cross-cultural adaptation of the Cardiac Rehabilitation Barriers Scale (CRBS) for use in Korea, followed by psychometric validation. The CRBS was developed to assess patients' perception of the degree to which patient, provider and health system-level barriers affect their cardiac rehabilitation (CR) participation. The CRBS consists of 21 items (barriers to adherence) rated on a 5-point Likert scale. The first phase was to translate and cross-culturally adapt the CRBS to the Korean language. After back-translation, both versions were reviewed by a committee. The face validity was assessed in a sample of Korean patients (n=53) with history of acute myocardial infarction that did not participate in CR through semi-structured interviews. The second phase was to assess the construct and criterion validity of the Korean translation as well as internal reliability, through administration of the translated version in 104 patients, principle component analysis with varimax rotation and cross-referencing against CR use, respectively. The length, readability, and clarity of the questionnaire were rated well, demonstrating face validity. Analysis revealed a six-factor solution, demonstrating construct validity. Cronbach's alpha was greater than 0.65. Barriers rated highest included not knowing about CR and not being contacted by a program. The mean CRBS score was significantly higher among non-attendees (2.71±0.26) than CR attendees (2.51±0.18) (p<0.01). The Korean version of CRBS has demonstrated face, content and criterion validity, suggesting it may be useful for assessing barriers to CR utilization in Korea.

Selection and Neutral Mutations Drive Pervasive Mutability Losses in Long-Lived Anti-HIV B-Cell Lineages

PubMed Central

Vieira, Marcos C; Zinder, Daniel; Cobey, Sarah

2018-01-01

Abstract High-affinity antibodies arise within weeks of infection from the evolution of B-cell receptors under selection to improve antigen recognition. This rapid adaptation is enabled by the distribution of highly mutable “hotspot” motifs in B-cell receptor genes. High mutability in antigen-binding regions (complementarity determining regions [CDRs]) creates variation in binding affinity, whereas low mutability in structurally important regions (framework regions [FRs]) may reduce the frequency of destabilizing mutations. During the response, loss of mutational hotspots and changes in their distribution across CDRs and FRs are predicted to compromise the adaptability of B-cell receptors, yet the contributions of different mechanisms to gains and losses of hotspots remain unclear. We reconstructed changes in anti-HIV B-cell receptor sequences and show that mutability losses were ∼56% more frequent than gains in both CDRs and FRs, with the higher relative mutability of CDRs maintained throughout the response. At least 21% of the total mutability loss was caused by synonymous mutations. However, nonsynonymous substitutions caused most (79%) of the mutability loss in CDRs. Because CDRs also show strong positive selection, this result suggests that selection for mutations that increase binding affinity contributed to loss of mutability in antigen-binding regions. Although recurrent adaptation to evolving viruses could indirectly select for high mutation rates, we found no evidence of indirect selection to increase or retain hotspots. Our results suggest mutability losses are intrinsic to both the neutral and adaptive evolution of B-cell populations and might constrain their adaptation to rapidly evolving pathogens such as HIV and influenza. PMID:29688540

Protection of adult rat cardiac myocytes from ischemic cell death: role of caveolar microdomains and delta-opioid receptors.

PubMed

Patel, Hemal H; Head, Brian P; Petersen, Heidi N; Niesman, Ingrid R; Huang, Diane; Gross, Garrett J; Insel, Paul A; Roth, David M

2006-07-01

The role of caveolae, membrane microenvironments enriched in signaling molecules, in myocardial ischemia is poorly defined. In the current study, we used cardiac myocytes prepared from adult rats to test the hypothesis that opioid receptors (OR), which are capable of producing cardiac protection in vivo, promote cardiac protection in cardiac myocytes in a caveolae-dependent manner. We determined protein expression and localization of delta-OR (DOR) using coimmunohistochemistry, caveolar fractionation, and immunoprecipitations. DOR colocalized in fractions with caveolin-3 (Cav-3), a structural component of caveolae in muscle cells, and could be immunoprecipitated by a Cav-3 antibody. Immunohistochemistry confirmed plasma membrane colocalization of DOR with Cav-3. Cardiac myocytes were subjected to simulated ischemia (2 h) or an ischemic preconditioning (IPC) protocol (10 min ischemia, 30 min recovery, 2 h ischemia) in the presence and absence of methyl-beta-cyclodextrin (MbetaCD, 2 mM), which binds cholesterol and disrupts caveolae. We also assessed the cardiac protective effects of SNC-121 (SNC), a selective DOR agonist, on cardiac myocytes with or without MbetaCD and MbetaCD preloaded with cholesterol. Ischemia, simulated by mineral oil layering to inhibit gas exchange, promoted cardiac myocyte cell death (trypan blue staining), a response blunted by SNC (37 +/- 3 vs. 59 +/- 3% dead cells in the presence and absence of 1 muM SNC, respectively, P < 0.01) or by use of the IPC protocol (35 +/- 4 vs. 62 +/- 3% dead cells, P < 0.01). MbetaCD treatment, which disrupted caveolae (as detected by electron microscopy), fully attenuated the protective effects of IPC or SNC, resulting in cell death comparable to that of the ischemic group. By contrast, SNC-induced protection was not abrogated in cells incubated with cholesterol-saturated MbetaCD, which maintained caveolae structure and function. These findings suggest a key role for caveolae, perhaps through enrichment of signaling molecules, in contributing to protection of cardiac myocytes from ischemic damage.

Influence of volatile anesthetics on muscarinic receptor adenylate cyclase coupling in brain and heart

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anthony, B.L.

In the present study, the influence of four volatile anesthetics (enflurane, isoflurane, diethyl ether, and chloroform) on (1) muscarinic receptor binding parameters and (2) muscarnic regulation of adenylate cyclase activity was examined using membranes isolated from rat brain and heart. Membranes were equilibrated with each of the four anesthetics for 30 minutes and then during the binding assay. The data obtained can be summarized as follows: (1) volatile anesthetics increased receptor affinity for a radiolabeled antagonists, ({sup 3}H)N-methylscopolamine (({sup 3}H)MS), by decreasing its rate of dissociation in brain stem, but not in cardiac, membranes, (2) volatile anesthetics decreased high affinitymore » ({sup 3}H)Oxotremorine-M binding, (3) volatile anesthetics depressed or eliminated the guanine nucleotide sensitivity of agonist binding. The influence of volatile anesthetics on muscarinic regulation of adenylate cyclase enzyme activity was studied using {alpha}({sup 32}P)ATP as the substrate.« less

Neuroaxial anaesthesia in obstetrical patients with cardiac disease.

PubMed

Gomar, Carmen; Errando, Carlos L

2005-10-01

Pregnancy and the peripartum period represent a physiological burden for the cardiac patient that can worsen even moderate degrees of cardiac disease. Valvular stenotic diseases, congenital cardiac disease, and coronary insufficiency are relatively frequent in pregnant patients. Since considerable variability exists in the cardiovascular changes and responses to labour among different cardiac diseases and their functional status, recommendations for anaesthetic management are based on reported clinical experience and pathophysiological concepts. Neuroaxial blockade reduces or even abolishes the cardiovascular stress response to pain, mitigates Valsalva effects by decreasing the pushing reflex, and allows the adaptation of analgesia or anaesthesia to labour stage and delivery. Sympathetic blockade caused by standard neuroaxial techniques, however, reduces systemic vascular resistance and cardiac preload followed by reflex tachycardia. Recent development of neuroaxial techniques with spinal opiates for the first stage of labour, carefully titrated segmental epidural analgesia with opiates combined with low concentrations of local anaesthetic for the second stage, and even low spinal anaesthesia for vaginal instrumental delivery, have all been used with good results in patients with severe cardiac disease. Only Tetralogy of Fallot, primary pulmonary hypertension, idiopathic hypertrophic subaortic stenosis, and anticoagulation are considered relative or absolute contraindications for neuroaxial techniques, though slow segmental blockade of dermatomes may offer an alternative. For Caesarean section, single shot spinal anaesthesia is not recommended in moderate or severe heart disease. Adequate cardiovascular invasive monitoring is essential and should be administered and maintained in the postpartum period with the same criteria that reduce morbidity and mortality in cardiac patients undergoing general surgery.

The impact of galectin-3 inhibition on aldosterone-induced cardiac and renal injuries.

PubMed

Calvier, Laurent; Martinez-Martinez, Ernesto; Miana, Maria; Cachofeiro, Victoria; Rousseau, Elodie; Sádaba, J Rafael; Zannad, Faiez; Rossignol, Patrick; López-Andrés, Natalia

2015-01-01

This study investigated whether galectin (Gal)-3 inhibition could block aldosterone-induced cardiac and renal fibrosis and improve cardiorenal dysfunction. Aldosterone is involved in cardiac and renal fibrosis that is associated with the development of cardiorenal injury. However, the mechanisms of these interactions remain unclear. Gal-3, a β-galactoside-binding lectin, is increased in heart failure and kidney injury. Rats were treated with aldosterone-salt combined with spironolactone (a mineralocorticoid receptor antagonist) or modified citrus pectin (a Gal-3 inhibitor), for 3 weeks. Wild-type and Gal-3 knockout mice were treated with aldosterone for 3 weeks. Hemodynamic, cardiac, and renal parameters were analyzed. Hypertensive aldosterone-salt-treated rats presented cardiac and renal hypertrophy (at morphometric, cellular, and molecular levels) and dysfunction. Cardiac and renal expressions of Gal-3 as well as levels of molecular markers attesting fibrosis were also augmented by aldosterone-salt treatment. Spironolactone or modified citrus pectin treatment reversed all of these effects. In wild-type mice, aldosterone did not alter blood pressure levels but increased cardiac and renal Gal-3 expression, fibrosis, and renal epithelial-mesenchymal transition. Gal-3 knockout mice were resistant to aldosterone effects. In experimental hyperaldosteronism, the increase in Gal-3 expression was associated with cardiac and renal fibrosis and dysfunction but was prevented by pharmacological inhibition (modified citrus pectin) or genetic disruption of Gal-3. These data suggest a key role for Gal-3 in cardiorenal remodeling and dysfunction induced by aldosterone. Gal-3 could be used as a new biotarget for specific pharmacological interventions. Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Valsartan attenuates cardiac and renal hypertrophy in rats with experimental cardiorenal syndrome possibly through down-regulating galectin-3 signaling.

PubMed

Zhang, M-J; Gu, Y; Wang, H; Zhu, P-F; Liu, X-Y; Wu, J

2016-01-01

Aortocaval fistula (AV) induced chronic volume overload in rats with preexisting mild renal dysfunction (right kidney remove: UNX) could mimic the type 4 cardiorenal syndrome (CRS): chronic renocardiac syndrome. Galectin-3, a β-galactoside binding lectin, is an emerging biomarker in cardiovascular as well as renal diseases. We observed the impact of valsartan on cardiac and renal hypertrophy and galectin-3 changes in this model. Adult male Sprague-Dawley (SD) rats (200-250 g) were divided into S (Sham, n = 7), M (UNX+AV, n = 7) and M+V (UNX+AV+valsartan, n = 7) groups. Eight weeks later, cardiac function was measured by echocardiography. Renal outcome was measured by glomerular filtration rate, effective renal plasma flow, renal blood flow and 24 hours albuminuria. Immunohistochemistry and real-time PCR were used to evaluate the expressions of galectin-3 in heart and renal. Cardiac hypertrophy and renal hypertrophy as well as cardiac enlargement were evidenced in this AV shunt induced chronic volume overload rat model with preexisting mild renal dysfunction. Cardiac and renal hypertrophy were significantly attenuated but cardiac enlargement was unaffected by valsartan independent of its blood pressure lowering effect. 24 hours urine albumin was significantly increased, which was significantly reduced by valsartan in this model. Immunohistochemistry and real-time PCR evidenced significantly up-regulated galectin-3 expression in heart and kidney and borderline increased myocardial collagen I expression, which tended to be lower post valsartan treatment. Up-regulated galectin-3 signaling might also be involved in the pathogenesis in this CRS model. The beneficial effects of valsartan in terms of attenuating cardiac and renal hypertrophy and reducing 24 hours albumin in this model might partly be mediated through down-regulating galectin-3 signal pathway.

Inhibition of cardiac sodium currents by toluene exposure

PubMed Central

Cruz, Silvia L; Orta-Salazar, Gerardo; Gauthereau, Marcia Y; Millan-Perez Peña, Lourdes; Salinas-Stefanón, Eduardo M

2003-01-01

Toluene is an industrial solvent widely used as a drug of abuse, which can produce sudden sniffing death due to cardiac arrhythmias. In this paper, we tested the hypothesis that toluene inhibits cardiac sodium channels in Xenopus laevis oocytes transfected with Nav1.5 cDNA and in isolated rat ventricular myocytes. In oocytes, toluene inhibited sodium currents (INa+) in a concentration-dependent manner, with an IC50 of 274 μM (confidence limits: 141–407μM). The inhibition was complete, voltage-independent, and slowly reversible. Toluene had no effect on: (i) the shape of the I–V curves; (ii) the reversal potential of Na+; and (iii) the steady-state inactivation. The slow recovery time constant from inactivation of INa+ decreased with toluene exposure, while the fast recovery time constant remained unchanged. Block of INa+ by toluene was use- and frequency-dependent. In rat cardiac myocytes, 300 μM toluene inhibited the sodium current (INa+) by 62%; this inhibition was voltage independent. These results suggest that toluene binds to cardiac Na+ channels in the open state and unbinds either when channels move between inactivated states or from an inactivated to a closed state. The use- and frequency-dependent block of INa+ by toluene might be responsible, at least in part, for its arrhythmogenic effect. PMID:14534149

Risk stratification of chronic heart failure patients by multiple biomarkers: implications of BNP, H-FABP, and PTX3.

PubMed

Ishino, Mitsunori; Takeishi, Yasuchika; Niizeki, Takeshi; Watanabe, Tetsu; Nitobe, Joji; Miyamoto, Takuya; Miyashita, Takehiko; Kitahara, Tatsuro; Suzuki, Satoshi; Sasaki, Toshiki; Bilim, Olga; Kubota, Isao

2008-11-01

B-type natriuretic peptide (BNP), heart-type fatty acid-binding protein (H-FABP), and pentraxin 3 (PTX3) each predict adverse cardiac events in chronic heart failure (CHF) patients. For prognostic evaluation from different aspects, the utility of combined measurement of the 3 biomarkers in patients with CHF was examined in the present study. Levels of BNP (associated with left ventricular dysfunction, positive if >200 pg/ml), H-FABP (marker of myocardial damage, positive if >4.1 ng/ml), and PTX3 (marker of inflammation, positive if >4.0 ng/ml) were measured in 164 consecutive CHF patients, and patients were prospectively followed with endpoints of cardiac death or rehospitalization. When patients were categorized on the basis of the number of elevated biomarkers, patients with 1, 2, and 3 elevated biomarkers had a 5.4-fold (not significant), 11.2-old (p<0.05), and 34.6-fold increase (p<0.01), respectively, in the risk of adverse cardiac events compared with those without elevated biomarkers. Kaplan-Meier analysis revealed that patients with 3 elevated biomarkers had a significantly higher cardiac event rate than patients with a lower number of elevated biomarkers. The combination of these 3 biomarkers could reliably risk-stratify CHF patients for prediction of cardiac events.

Adaptive Focused Acoustics (AFA) Improves the Performance of Microtiter Plate ELISAs.

PubMed

Green, David J; Rudd, Edwin A; Laugharn, James A

2014-08-01

We investigated the use of Adaptive Focused Acoustics (AFA) technology to improve the performance of microtiter plate enzyme-linked immunosorbent assays (ELISAs). Experiments were performed with commercially available AFA instrumentation and off-the-shelf 96-well microtiter plate sandwich ELISAs. AFA was applied over a range of acoustic energies, temperatures, and durations to the antigen/antibody binding step of an ELISA for measuring HIV-1 p24 in tissue culture samples. AFA-mediated antigen/antibody binding was enhanced up to 2-fold over passive binding at comparable temperatures and was superior or comparable at low temperature (8-10 °C) to passive binding at 37 °C. Lower nonspecific binding (NSB), lower inter- and intra-assay coefficients of variation (CVs), higher Z' factors, and lower limits of detection (LODs) were measured in AFA-mediated assays compared with conventional passive binding. In a more limited study, AFA enhancement of antigen/antibody binding and lower NSB was measured in an ELISA for measuring IGFBP-3 in human plasma. We conclude from this study that application of AFA to antigen/antibody binding steps in microtiter plate ELISAs can enhance key assay performance parameters, particularly Z' factors and LODs. These features render AFA-mediated binding assays potentially more useful in applications such as high-throughput screening and in vitro diagnostics than assays processed with conventional passive antigen/antibody binding steps. © 2014 Society for Laboratory Automation and Screening.

Engineered Escherichia coli Silver-Binding Periplasmic Protein That Promotes Silver Tolerance

PubMed Central

Hall Sedlak, Ruth; Hnilova, Marketa; Grosh, Carolynn; Fong, Hanson; Baneyx, Francois; Schwartz, Dan; Sarikaya, Mehmet; Tamerler, Candan

2012-01-01

Silver toxicity is a problem that microorganisms face in medical and environmental settings. Through exposure to silver compounds, some bacteria have adapted to growth in high concentrations of silver ions. Such adapted microbes may be dangerous as pathogens but, alternatively, could be potentially useful in nanomaterial-manufacturing applications. While naturally adapted isolates typically utilize efflux pumps to achieve metal resistance, we have engineered a silver-tolerant Escherichia coli strain by the use of a simple silver-binding peptide motif. A silver-binding peptide, AgBP2, was identified from a combinatorial display library and fused to the C terminus of the E. coli maltose-binding protein (MBP) to yield a silver-binding protein exhibiting nanomolar affinity for the metal. Growth experiments performed in the presence of silver nitrate showed that cells secreting MBP-AgBP2 into the periplasm exhibited silver tolerance in a batch culture, while those expressing a cytoplasmic version of the fusion protein or MBP alone did not. Transmission electron microscopy analysis of silver-tolerant cells revealed the presence of electron-dense silver nanoparticles. This is the first report of a specifically engineered metal-binding peptide exhibiting a strong in vivo phenotype, pointing toward a novel ability to manipulate bacterial interactions with heavy metals by the use of short and simple peptide motifs. Engineered metal-ion-tolerant microorganisms such as this E. coli strain could potentially be used in applications ranging from remediation to interrogation of biomolecule-metal interactions in vivo. PMID:22286990

Immune Modulation of Cardiac Repair and Regeneration: The Art of Mending Broken Hearts

PubMed Central

Zlatanova, Ivana; Pinto, Cristina; Silvestre, Jean-Sébastien

2016-01-01

The accumulation of immune cells is among the earliest responses that manifest in the cardiac tissue after injury. Both innate and adaptive immunity coordinate distinct and mutually non-exclusive events governing cardiac repair, including elimination of the cellular debris, compensatory growth of the remaining cardiac tissue, activation of resident or circulating precursor cells, quantitative and qualitative modifications of the vascular network, and formation of a fibrotic scar. The present review summarizes the mounting evidence suggesting that the inflammatory response also guides the regenerative process following cardiac damage. In particular, recent literature has reinforced the central role of monocytes/macrophages in poising the refreshment of cardiomyocytes in myocardial infarction- or apical resection-induced cardiac insult. Macrophages dictate cardiac myocyte renewal through stimulation of preexisting cardiomyocyte proliferation and/or neovascularization. Nevertheless, substantial efforts are required to identify the nature of these macrophage-derived factors as well as the molecular mechanisms engendered by the distinct subsets of macrophages pertaining in the cardiac tissue. Among the growing inflammatory intermediaries that have been recognized as essential player in heart regeneration, we will focus on the role of interleukin (IL)-6 and IL-13. Finally, it is likely that within the mayhem of the injured cardiac tissue, additional types of inflammatory cells, such as neutrophils, will enter the dance to ignite and refresh the broken heart. However, the protective and detrimental inflammatory pathways have been mainly deciphered in animal models. Future research should be focused on understanding the cellular effectors and molecular signals regulating inflammation in human heart to pave the way for the development of factual therapies targeting the inflammatory compartment in cardiac diseases. PMID:27790620

Immune Modulation of Cardiac Repair and Regeneration: The Art of Mending Broken Hearts.

PubMed

Zlatanova, Ivana; Pinto, Cristina; Silvestre, Jean-Sébastien

2016-01-01

The accumulation of immune cells is among the earliest responses that manifest in the cardiac tissue after injury. Both innate and adaptive immunity coordinate distinct and mutually non-exclusive events governing cardiac repair, including elimination of the cellular debris, compensatory growth of the remaining cardiac tissue, activation of resident or circulating precursor cells, quantitative and qualitative modifications of the vascular network, and formation of a fibrotic scar. The present review summarizes the mounting evidence suggesting that the inflammatory response also guides the regenerative process following cardiac damage. In particular, recent literature has reinforced the central role of monocytes/macrophages in poising the refreshment of cardiomyocytes in myocardial infarction- or apical resection-induced cardiac insult. Macrophages dictate cardiac myocyte renewal through stimulation of preexisting cardiomyocyte proliferation and/or neovascularization. Nevertheless, substantial efforts are required to identify the nature of these macrophage-derived factors as well as the molecular mechanisms engendered by the distinct subsets of macrophages pertaining in the cardiac tissue. Among the growing inflammatory intermediaries that have been recognized as essential player in heart regeneration, we will focus on the role of interleukin (IL)-6 and IL-13. Finally, it is likely that within the mayhem of the injured cardiac tissue, additional types of inflammatory cells, such as neutrophils, will enter the dance to ignite and refresh the broken heart. However, the protective and detrimental inflammatory pathways have been mainly deciphered in animal models. Future research should be focused on understanding the cellular effectors and molecular signals regulating inflammation in human heart to pave the way for the development of factual therapies targeting the inflammatory compartment in cardiac diseases.

Characterizing the role of endothelin-1 in the progression of cardiac hypertrophy in aryl hydrocarbon receptor (AhR) null mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lund, Amie K.; Goens, M. Beth; Nunez, Bethany A.

2006-04-15

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor characterized to play a role in detection and adaptation to environmental stimuli. Genetic deletion of AhR results in hypertension, and cardiac hypertrophy and fibrosis, associated with elevated plasma angiotensin II (Ang II) and endothelin-1 (ET-1), thus AhR appears to contribute to cardiovascular homeostasis. In these studies, we tested the hypothesis that ET-1 mediates cardiovascular pathology in AhR null mice via ET{sub A} receptor activation. First, we determine the time courses of cardiac hypertrophy, and of plasma and tissue ET-1 expression in AhR wildtype and null mice. AhR null mice exhibitedmore » increases in heart-to-body weight ratio and age-related expression of cardiac hypertrophy markers, {beta}-myosin heavy chain ({beta}-MHC), and atrial natriuretic factor (ANF), which were significant at 2 months. Similarly, plasma and tissue ET-1 expression was significantly elevated at 2 months and increased further with age. Second, AhR null mice were treated with ET{sub A} receptor antagonist, BQ-123 (100 nmol/kg/day), for 7, 28, or 58 days and blood pressure, cardiac fibrosis, and cardiac hypertrophy assessed, respectively. BQ-123 for 7 days significantly reduced mean arterial pressure in conscious, catheterized mice. BQ-123 for 28 days significantly reduced the histological appearance of cardiac fibrosis. Treatment for 58 days significantly reduced cardiac mass, assessed by heart weight, echocardiography, and {beta}-MHC and ANF expression; and reduced cardiac fibrosis as determined by osteopontin and collagen I mRNA expression. These findings establish ET-1 and the ET{sub A} receptor as primary determinants of hypertension and cardiac pathology in AhR null mice.« less

Membrane estrogen receptor alpha is an important modulator of bone marrow C-Kit+ cells mediated cardiac repair after myocardial infarction

PubMed Central

Su, Feng; Zhang, Wentian; Liu, Jianfang

2015-01-01

It has been validated that c-kit positive (c-kit+) cells in infarcted myocardium are from bone marrow (BM). Given the recent study that in the heart, estrogen receptor alpha (ERα) is involved in adaptive mechanisms by supporting cardiomyocytes survival via post-infarct cardiac c-kit+ cells, we tested a novel hypothesis that membrane ERα (mERа) supports survival of BM c-kit+ cells and enhance protective paracrine function for cardiac repair. Our data showed that myocardial infarction (MI) leads to an increase in c-kit+ first in bone marrow and then specifically within the infarcted myocardium. Also up-regulated mERа in post-infarct BM c-kit+ cells was found in day 3 post MI. In vitro co-culture system, mERа+ enhances the beneficial effects of BM c-kit+ cells by increasing their viability and reducing apoptosis. Post-infarct c-kit+ mERа+ cells population expresses predominant ERα and holds self-renewal as well as cardiac differentiation potentials after MI. In vivo, BM c-kit+ cells reduced infarct size, fibrosis and improved cardiac function. In conclusion, BM c-kit+ mERа+ exerted significantly cardiac protection after MI. A potential important implication of this study is that the manipulation of BM c-kit+ stem cells with ERа-dependent fashion may be helpful in recovering functional performance after cardiac tissue injury. PMID:26191121

Growth and differentiation factor 11 (GDF11): Functions in the regulation of erythropoiesis and cardiac regeneration.

PubMed

Rochette, Luc; Zeller, Marianne; Cottin, Yves; Vergely, Catherine

2015-12-01

Members of the TGF-β superfamily transduce their signals through type I and II receptor serine/threonine kinases. The regulation of members of the TGF-β family is known to be complex, because many proteins able to bind the ligands and inhibit their activities have been identified. Growth and differentiation factor 11 (Gdf11) as activins belong to the TGF-β family. GDF11, like other members of the TGF-β superfamily, is produced from precursor proteins by proteolytic processing. The binding of activins to activin type IIA (ActRIIA) or type IIB (ActRIIB) receptors induces the recruitment and phosphorylation of an activin type I receptor which then phosphorylates the Smad2 and Smad3 intracellular signaling proteins. GDF11 signal through the ActRIIB pathway. Recent studies have reported that GDF11-ActRIIB-Smad2/3-dependent signaling is a key regulatory mechanism in proliferating erythroid precursors as it controls their late-stage maturation. The administration of GDF11 is effective in experimental cardiac hypertrophy, and the identification of GDF11 as a "rejuvenating factor" opens up perspectives for the treatment of age-related cardiac dysfunction. Recent studies of the heart indicate that exposure to young blood reverses age-related impairments. GDF11 could be one of the circulating molecules that influence the aging of different tissues. Is GDF11 an "elixir of youth"? Copyright © 2015 Elsevier Inc. All rights reserved.

Allosteric modulation of cardiac myosin dynamics by omecamtiv mecarbil

PubMed Central

Tiberti, Matteo

2017-01-01

New promising avenues for the pharmacological treatment of skeletal and heart muscle diseases rely on direct sarcomeric modulators, which are molecules that can directly bind to sarcomeric proteins and either inhibit or enhance their activity. A recent breakthrough has been the discovery of the myosin activator omecamtiv mecarbil (OM), which has been shown to increase the power output of the cardiac muscle and is currently in clinical trials for the treatment of heart failure. While the overall effect of OM on the mechano-chemical cycle of myosin is to increase the fraction of myosin molecules in the sarcomere that are strongly bound to actin, the molecular basis of its action is still not completely clear. We present here a Molecular Dynamics study of the motor domain of human cardiac myosin bound to OM, where the effects of the drug on the dynamical properties of the protein are investigated for the first time with atomistic resolution. We found that OM has a double effect on myosin dynamics, inducing a) an increased coupling of the motions of the converter and lever arm subdomains to the rest of the protein and b) a rewiring of the network of dynamic correlations, which produces preferential communication pathways between the OM binding site and distant functional regions. The location of the residues responsible for these effects suggests possible strategies for the future development of improved drugs and the targeting of specific cardiomyopathy-related mutations. PMID:29108014

The influence of hormonal and neuronal factors on rat heart adrenoceptors

PubMed Central

Kunos, George; Mucci, Lucia; O'Regan, Seana

1980-01-01

1 The influence of hormonal and neuronal factors on adrenoceptors mediating increased cardiac force and rate of contraction were studied in rat isolated atria. The pharmacological properties of these receptors were deduced from the relative potencies of agonists and from the effects of selective α- and β-adrenoceptor antagonists. The numbers and affinities of α- and β-adrenoceptors were also determined by radioligand binding to ventricular membrane fragments. 2 Hypophysectomy reduced the inotropic potency of isoprenaline and increased the potency of phenylephrine and methoxamine in left atria. The effect of phenylephrine was inhibited by propranolol less effectively and by phentolamine or phenoxybenzamine more effectively in hypophysectomized than in control rats. The difference in block was smaller at low than at high antagonist concentrations. Similar but smaller changes were observed for chronotropic responses of right atria. 3 The decreased β- and increased α-receptor response after hypophysectomy was similar to that observed earlier in thyroidectomized rats (Kunos, 1977). These changes developed slowly after hypophysectomy (>2 weeks), they were both reversed within 2 days of thyroxine treatment (0.2 mg/kg daily), but were not affected by cortisone treatment (50 mg/kg every 12 h for 4 days). 4 Treatment of hypophysectomized rats for 2 days with thyroxine increased the density of [3H]-dihydroalprenolol ([3H]-DHA) binding sites from 27.5 ± 2.7 to 45.5 ± 5.7 fmol/mg protein and decreased the density of [3H]-WB-4101 binding sites from 38.7 ± 3.1 to 18.7 ± 2.5 fmol/mg protein. The affinity of either type of binding site for agonists or antagonist was not significantly altered by thyroxine treatment and the sum total of α1- and β-receptors remained the same. 5 Sympathetic denervation of thyroidectomized rats by 6-hydroxydopamine increased the inotropic potency of isoprenaline and noradrenaline and the blocking effect of propranolol, and decreased the potency of phenylephrine and the blocking effect of phenoxybenzamine to or beyond values observed in euthyroid controls. The density of [3H]-DHA binding sites was higher and that of [3H]-WB-4101 binding sites was lower in the denervated than in the innervated hypothyroid myocardium. Depletion of endogenous noradrenaline stores by reserpine did not significantly alter the adrenoceptor response pattern of the hypothyroid preparations and did not influence the density or affinity of [3H]-DHA and [3H]-WB-4101 binding sites. 6 These results indicate that thyrotropin or steroids do not contribute to the reciprocal changes in the sensitivity of cardiac α1- and β-adrenoceptors in altered thyroid states. These thyroid hormone-dependent changes are probably due to a parallel, reciprocal change in the numbers but not the affinities of α1- and β-adrenoceptors. Reciprocal regulation of cardiac α1- and β-adrenoceptors by thyroid hormones requires intact sympathetic innervation but not the presence of normal stores of the neurotransmitter. PMID:7470752

Inferring dynamic gene regulatory networks in cardiac differentiation through the integration of multi-dimensional data.

PubMed

Gong, Wuming; Koyano-Nakagawa, Naoko; Li, Tongbin; Garry, Daniel J

2015-03-07

Decoding the temporal control of gene expression patterns is key to the understanding of the complex mechanisms that govern developmental decisions during heart development. High-throughput methods have been employed to systematically study the dynamic and coordinated nature of cardiac differentiation at the global level with multiple dimensions. Therefore, there is a pressing need to develop a systems approach to integrate these data from individual studies and infer the dynamic regulatory networks in an unbiased fashion. We developed a two-step strategy to integrate data from (1) temporal RNA-seq, (2) temporal histone modification ChIP-seq, (3) transcription factor (TF) ChIP-seq and (4) gene perturbation experiments to reconstruct the dynamic network during heart development. First, we trained a logistic regression model to predict the probability (LR score) of any base being bound by 543 TFs with known positional weight matrices. Second, four dimensions of data were combined using a time-varying dynamic Bayesian network model to infer the dynamic networks at four developmental stages in the mouse [mouse embryonic stem cells (ESCs), mesoderm (MES), cardiac progenitors (CP) and cardiomyocytes (CM)]. Our method not only infers the time-varying networks between different stages of heart development, but it also identifies the TF binding sites associated with promoter or enhancers of downstream genes. The LR scores of experimentally verified ESCs and heart enhancers were significantly higher than random regions (p <10(-100)), suggesting that a high LR score is a reliable indicator for functional TF binding sites. Our network inference model identified a region with an elevated LR score approximately -9400 bp upstream of the transcriptional start site of Nkx2-5, which overlapped with a previously reported enhancer region (-9435 to -8922 bp). TFs such as Tead1, Gata4, Msx2, and Tgif1 were predicted to bind to this region and participate in the regulation of Nkx2-5 gene expression. Our model also predicted the key regulatory networks for the ESC-MES, MES-CP and CP-CM transitions. We report a novel method to systematically integrate multi-dimensional -omics data and reconstruct the gene regulatory networks. This method will allow one to rapidly determine the cis-modules that regulate key genes during cardiac differentiation.

The HCM-linked W792R mutation in cardiac myosin-binding protein C reduces C6 FnIII domain stability.

PubMed

Smelter, Dan F; de Lange, Willem J; Cai, Wenxuan; Ge, Ying; Ralphe, J Carter

2018-06-01

Cardiac myosin-binding protein C (cMyBP-C) is a functional sarcomeric protein that regulates contractility in response to contractile demand, and many mutations in cMyBP-C lead to hypertrophic cardiomyopathy (HCM). To gain insight into the effects of disease-causing cMyBP-C missense mutations on contractile function, we expressed the pathogenic W792R mutation (substitution of a highly conserved tryptophan residue by an arginine residue at position 792) in mouse cardiomyocytes lacking endogenous cMyBP-C and studied the functional effects using three-dimensional engineered cardiac tissue constructs (mECTs). Based on complete conservation of tryptophan at this location in fibronectin type II (FnIII) domains, we hypothesized that the W792R mutation affects folding of the C6 FnIII domain, destabilizing the mutant protein. Adenoviral transduction of wild-type (WT) and W792R cDNA achieved equivalent mRNA transcript abundance, but not equivalent protein levels, with W792R compared with WT controls. mECTs expressing W792R demonstrated abnormal contractile kinetics compared with WT mECTs that were nearly identical to cMyBP-C-deficient mECTs. We studied whether common pathways of protein degradation were responsible for the rapid degradation of W792R cMyBP-C. Inhibition of both ubiquitin-proteasome and lysosomal degradation pathways failed to increase full-length mutant protein abundance to WT equivalence, suggesting rapid cytosolic degradation. Bacterial expression of WT and W792R protein fragments demonstrated decreased mutant stability with altered thermal denaturation and increased susceptibility to trypsin digestion. These data suggest that the W792R mutation destabilizes the C6 FnIII domain of cMyBP-C, resulting in decreased full-length protein expression. This study highlights the vulnerability of FnIII-like domains to mutations that alter domain stability and further indicates that missense mutations in cMyBP-C can cause disease through a mechanism of haploinsufficiency. NEW & NOTEWORTHY This study is one of the first to describe a disease mechanism for a missense mutation in cardiac myosin-binding protein C linked to hypertrophic cardiomyopathy. The mutation decreases stability of the fibronectin type III domain and results in substantially reduced mutant protein expression dissonant to transcript abundance.

Thin filament length in the cardiac sarcomere varies with sarcomere length but is independent of titin and nebulin.

PubMed

Kolb, Justin; Li, Frank; Methawasin, Mei; Adler, Maya; Escobar, Yael-Natalie; Nedrud, Joshua; Pappas, Christopher T; Harris, Samantha P; Granzier, Henk

2016-08-01

Thin filament length (TFL) is an important determinant of the force-sarcomere length (SL) relation of cardiac muscle. However, the various mechanisms that control TFL are not well understood. Here we tested the previously proposed hypothesis that the actin-binding protein nebulin contributes to TFL regulation in the heart by using a cardiac-specific nebulin cKO mouse model (αMHC Cre Neb cKO). Atrial myocytes were studied because nebulin expression has been reported to be most prominent in this cell type. TFL was measured in right and left atrial myocytes using deconvolution optical microscopy and staining for filamentous actin with phalloidin and for the thin filament pointed-end with an antibody to the capping protein Tropomodulin-1 (Tmod1). Results showed that TFLs in Neb cKO and littermate control mice were not different. Thus, deletion of nebulin in the heart does not alter TFL. However, TFL was found to be ~0.05μm longer in the right than in the left atrium and Tmod1 expression was increased in the right atrium. We also tested the hypothesis that the length of titin's spring region is a factor controlling TFL by studying the Rbm20(ΔRRM) mouse which expresses titins that are ~500kDa (heterozygous mice) and ~1000kDa (homozygous mice) longer than in control mice. Results revealed that TFL was not different in Rbm20(ΔRRM) mice. An unexpected finding in all genotypes studied was that TFL increased as sarcomeres were stretched (~0.1μm per 0.35μm of SL increase). This apparent increase in TFL reached a maximum at a SL of ~3.0μm where TFL was ~1.05μm. The SL dependence of TFL was independent of chemical fixation or the presence of cardiac myosin-binding protein C (cMyBP-C). In summary, we found that in cardiac myocytes TFL varies with SL in a manner that is independent of the size of titin or the presence of nebulin. Copyright © 2016. Published by Elsevier Ltd.

Synergistic effects of low-intensity exercise conditioning and β-blockade on cardiovascular and autonomic adaptation in pre- and postmenopausal women with hypertension.

PubMed

Goldie, Catherine L; Brown, C Ann; Hains, Sylvia M J; Parlow, Joel L; Birtwhistle, Richard

2013-10-01

The effects of a 12-week low-intensity exercise conditioning program (walking) on blood pressure (BP), heart rate (HR), rate-pressure product (RPP), and cardiac autonomic function were measured in 40 sedentary women with hypertension. Women were assigned to either an exercise group (n = 20) or a control group (n = 20), matched for β-blockade treatment. They underwent testing at the beginning and at the end of the 12-week study period in three conditions: supine rest, standing, and low-intensity steady state exercise. The exercise group participated in a 12-week, low-intensity walking program, while the control group continued with usual sedentary activity. Compared with the control group, women in the exercise group showed reductions in systolic and diastolic BP and RPP (i.e., the estimated cardiac workload). β-Blockers increased baroreflex sensitivity and lowered BP and HR in all participants; however, those in the exercise group showed the effects of both treatments: a greater reduction in HR and RPP. The combination of exercise training and β-blockade produces cardiac and autonomic adaptations that are not observed with either treatment alone, suggesting that β-blockade enhances the conditioning effects of low-intensity exercise in women with hypertension.

Proteasome Inhibition Contributed to the Cytotoxicity of Arenobufagin after Its Binding with Na, K-ATPase in Human Cervical Carcinoma HeLa Cells

PubMed Central

Zhen, Hong; Huang, Ming; Zheng, Xi; Feng, Lixing; Jiang, Baohong; Yang, Min; Wu, Wanying; Liu, Xuan; Guo, Dean

2016-01-01

Although the possibility of developing cardiac steroids/cardiac glycosides as novel cancer therapeutic agents has been recognized, the mechanism of their anticancer activity is still not clear enough. Toad venom extract containing bufadienolides, which belong to cardiac steroids, has actually long been used as traditional Chinese medicine in clinic for cancer therapy in China. The cytotoxicity of arenobufagin, a bufadienolide isolated from toad venom, on human cervical carcinoma HeLa cells was checked. And, the protein expression profile of control HeLa cells and HeLa cells treated with arenobufagin for 48 h was analyzed using two-dimensional electrophoresis, respectively. Differently expressed proteins in HeLa cells treated with arenobufagin were identified and the pathways related to these proteins were mapped from KEGG database. Computational molecular docking was performed to verify the binding of arenobufagin and Na, K-ATPase. The effects of arenobufagin on Na, K-ATPase activity and proteasome activity of HeLa cells were checked. The protein-protein interaction network between Na, K-ATPase and proteasome was constructed and the expression of possible intermediate proteins ataxin-1 and translationally-controlled tumor protein in HeLa cells treated with arenobufagin was then checked. Arenobufagin induced apoptosis and G2/M cell cycle arrest in HeLa cells. The cytotoxic effect of arenobufagin was associated with 25 differently expressed proteins including proteasome-related proteins, calcium ion binding-related proteins, oxidative stress-related proteins, metabolism-related enzymes and others. The results of computational molecular docking revealed that arenobufagin was bound in the cavity formed by the transmembrane alpha subunits of Na, K-ATPase, which blocked the pathway of extracellular Na+/K+ cation exchange and inhibited the function of ion exchange. Arenobufagin inhibited the activity of Na, K-ATPase and proteasome, decreased the expression of Na, K-ATPase α1 and α3 subunits and increased the expression of WEE1 in HeLa cells. Antibodies against Na, K-ATPase α1 and α3 subunits alone or combinated with arenobufagin also inhibited the activity of proteasome. Furthermore, the expression of the possible intermediate proteins ataxin-1 and translationally-controlled tumor protein was increased in HeLa cells treated with arenobufagin by flow cytometry analysis, respectively. These results indicated that arenobufagin might directly bind with Na, K-ATPase α1 and α3 subunits and the inhibitive effect of arenobufagin on proteasomal activity of HeLa cells might be related to its binding with Na, K-ATPase. PMID:27428326

Proteasome Inhibition Contributed to the Cytotoxicity of Arenobufagin after Its Binding with Na, K-ATPase in Human Cervical Carcinoma HeLa Cells.

PubMed

Yue, Qingxi; Zhen, Hong; Huang, Ming; Zheng, Xi; Feng, Lixing; Jiang, Baohong; Yang, Min; Wu, Wanying; Liu, Xuan; Guo, Dean

2016-01-01

Although the possibility of developing cardiac steroids/cardiac glycosides as novel cancer therapeutic agents has been recognized, the mechanism of their anticancer activity is still not clear enough. Toad venom extract containing bufadienolides, which belong to cardiac steroids, has actually long been used as traditional Chinese medicine in clinic for cancer therapy in China. The cytotoxicity of arenobufagin, a bufadienolide isolated from toad venom, on human cervical carcinoma HeLa cells was checked. And, the protein expression profile of control HeLa cells and HeLa cells treated with arenobufagin for 48 h was analyzed using two-dimensional electrophoresis, respectively. Differently expressed proteins in HeLa cells treated with arenobufagin were identified and the pathways related to these proteins were mapped from KEGG database. Computational molecular docking was performed to verify the binding of arenobufagin and Na, K-ATPase. The effects of arenobufagin on Na, K-ATPase activity and proteasome activity of HeLa cells were checked. The protein-protein interaction network between Na, K-ATPase and proteasome was constructed and the expression of possible intermediate proteins ataxin-1 and translationally-controlled tumor protein in HeLa cells treated with arenobufagin was then checked. Arenobufagin induced apoptosis and G2/M cell cycle arrest in HeLa cells. The cytotoxic effect of arenobufagin was associated with 25 differently expressed proteins including proteasome-related proteins, calcium ion binding-related proteins, oxidative stress-related proteins, metabolism-related enzymes and others. The results of computational molecular docking revealed that arenobufagin was bound in the cavity formed by the transmembrane alpha subunits of Na, K-ATPase, which blocked the pathway of extracellular Na+/K+ cation exchange and inhibited the function of ion exchange. Arenobufagin inhibited the activity of Na, K-ATPase and proteasome, decreased the expression of Na, K-ATPase α1 and α3 subunits and increased the expression of WEE1 in HeLa cells. Antibodies against Na, K-ATPase α1 and α3 subunits alone or combinated with arenobufagin also inhibited the activity of proteasome. Furthermore, the expression of the possible intermediate proteins ataxin-1 and translationally-controlled tumor protein was increased in HeLa cells treated with arenobufagin by flow cytometry analysis, respectively. These results indicated that arenobufagin might directly bind with Na, K-ATPase α1 and α3 subunits and the inhibitive effect of arenobufagin on proteasomal activity of HeLa cells might be related to its binding with Na, K-ATPase.

The Impact of Juvenile Coxsackievirus Infection on Cardiac Progenitor Cells and Postnatal Heart Development

PubMed Central

Sin, Jon; Puccini, Jenna M.; Huang, Chengqun; Konstandin, Mathias H.; Gilbert, Paul E.; Sussman, Mark A.; Gottlieb, Roberta A.; Feuer, Ralph

2014-01-01

Coxsackievirus B (CVB) is an enterovirus that most commonly causes a self-limited febrile illness in infants, but cases of severe infection can manifest in acute myocarditis. Chronic consequences of mild CVB infection are unknown, though there is an epidemiologic association between early subclinical infections and late heart failure, raising the possibility of subtle damage leading to late-onset dysfunction, or chronic ongoing injury due to inflammatory reactions during latent infection. Here we describe a mouse model of juvenile infection with a subclinical dose of coxsackievirus B3 (CVB3) which showed no evident symptoms, either immediately following infection or in adult mice. However following physiological or pharmacologically-induced cardiac stress, juvenile-infected adult mice underwent cardiac hypertrophy and dilation indicative of progression to heart failure. Evaluation of the vasculature in the hearts of adult mice subjected to cardiac stress showed a compensatory increase in CD31+ blood vessel formation, although this effect was suppressed in juvenile-infected mice. Moreover, CVB3 efficiently infected juvenile c-kit+ cells, and cardiac progenitor cell numbers were reduced in the hearts of juvenile-infected adult mice. These results suggest that the exhausted cardiac progenitor cell pool following juvenile CVB3 infection may impair the heart's ability to increase capillary density to adapt to increased load. PMID:25079373

Understanding Key Mechanisms of Exercise-Induced Cardiac Protection to Mitigate Disease: Current Knowledge and Emerging Concepts.

PubMed

Bernardo, Bianca C; Ooi, Jenny Y Y; Weeks, Kate L; Patterson, Natalie L; McMullen, Julie R

2018-01-01

The benefits of exercise on the heart are well recognized, and clinical studies have demonstrated that exercise is an intervention that can improve cardiac function in heart failure patients. This has led to significant research into understanding the key mechanisms responsible for exercise-induced cardiac protection. Here, we summarize molecular mechanisms that regulate exercise-induced cardiac myocyte growth and proliferation. We discuss in detail the effects of exercise on other cardiac cells, organelles, and systems that have received less or little attention and require further investigation. This includes cardiac excitation and contraction, mitochondrial adaptations, cellular stress responses to promote survival (heat shock response, ubiquitin-proteasome system, autophagy-lysosomal system, endoplasmic reticulum unfolded protein response, DNA damage response), extracellular matrix, inflammatory response, and organ-to-organ crosstalk. We summarize therapeutic strategies targeting known regulators of exercise-induced protection and the challenges translating findings from bench to bedside. We conclude that technological advancements that allow for in-depth profiling of the genome, transcriptome, proteome and metabolome, combined with animal and human studies, provide new opportunities for comprehensively defining the signaling and regulatory aspects of cell/organelle functions that underpin the protective properties of exercise. This is likely to lead to the identification of novel biomarkers and therapeutic targets for heart disease.

Cardiopulmonary reflex, cardiac cytokines, and nandrolone decanoate: response to resistance training in rats.

PubMed

Lima, Ewelyne Miranda; Nascimento, Andrews Marques; Brasil, Girlandia Alexandre; Kalil, Ieda Carneiro; Lenz, Dominik; Endringer, Denise Coutinho; Andrade, Tadeu Uggere; Bissoli, Nazaré Souza

2015-11-01

This study evaluated the effects of nandrolone associated with resistance training (RT) on cardiac cytokines, angiotensin-converting enzyme activity (ACEA), and the sensitivity of the Bezold-Jarisch reflex (BJR). Male Wistar rats were divided into 3 groups: CONT (received vehicle, no training); EXERC (RT: after one week of water adaptation, rats were exercised by jumping into water twice a week for 4 weeks), and ND+EXERC (received nandrolone decanoate 10 mg/kg, twice/week, i.m, associated with RT). The BJR was analysed by measuring bradycardic and hypotensive responses elicited by serotonin administration. Myocyte hypertrophy and matrix collagen deposition were determined by morphometric analysis of H&E and picrosirius red-stained samples, respectively. TNF-α and ACEA were also studied. RT promoted physiological myocyte hyrpertrophy but did not cause changes in the other parameters. The association of ND with RT increased myocyte hypertrophy, deposition of matrix type I collagen, TNF-α and ACEA; decreased IL-10, and impairment in the BJR were observed in ND+EXERC compared with CONT and EXERC. ND is associated with alterations in cardiac structure and function as a result of the development of pathological cardiac hypertrophy (cardiac cytokine imbalance, elevation of ACEA) and cardiac injury, even when combined with resistance training.

Fetal Cardiac Impairment in Nitrofen-Induced Congenital Diaphragmatic Hernia: Postmortem Microcomputed Tomography Imaging Study.

PubMed

Pelizzo, Gloria; Calcaterra, Valeria; Lombardi, Claudio; Bussani, Rossana; Zambelli, Vanessa; De Silvestri, Annalisa; Custrin, Ana; Belgrano, Manuel; Zennaro, Floriana

2017-08-01

We assessed the post-mortem micro-CT utility to evaluate fetal cardiac impairment in nitrofen-induced congenital diaphragmatic hernia (CDH). At 9.5d postconception (dpc), pregnant rats were exposed to nitrofen. At +18 and +21dpc, fetuses were harvested by cesarean section. Postmortem micro-CT and autopsy were performed. Fetuses were assigned to three experimental groups: Control group (C), Nitrofen group (N, exposition to nitrofen without CDH), CDH group. Cardio-pulmonary indices were evaluated. An accurate morphological evaluation of the lung and heart was obtained. Early cardiac impairment was present in the N and CDH groups. At term pregnancy, an increased maximum diameter and decreased minimum diameter of the ventricles and increased interventricular septal thickness were noted in CDH. Histology showed a myocardial "disarray" and an high density of mitotic myocytes in CDH at midgestation. The potential utility of post-mortem fetal micro-CT examination in CDH was introduced. The results highlighted the presence of cardiac adaptation in affected fetuses.

Influence of gravity on cardiac performance.

PubMed

Pantalos, G M; Sharp, M K; Woodruff, S J; O'Leary, D S; Lorange, R; Everett, S D; Bennett, T E; Shurfranz, T

1998-01-01

Results obtained by the investigators in ground-based experiments and in two parabolic flight series of tests aboard the NASA KC-135 aircraft with a hydraulic simulator of the human systemic circulation have confirmed that a simple lack of hydrostatic pressure within an artificial ventricle causes a decrease in stroke volume of 20%-50%. A corresponding drop in stroke volume (SV) and cardiac output (CO) was observed over a range of atrial pressures (AP), representing a rightward shift of the classic CO versus AP cardiac function curve. These results are in agreement with echocardiographic experiments performed on space shuttle flights, where an average decrease in SV of 15% was measured following a three-day period of adaptation to weightlessness. The similarity of behavior of the hydraulic model to the human system suggests that the simple physical effects of the lack of hydrostatic pressure may be an important mechanism for the observed changes in cardiac performance in astronauts during the weightlessness of space flight.

Elevated Glucose Oxidation, Reduced Insulin Secretion, and a Fatty Heart May Be Protective Adaptions in Ischemic CAD.

PubMed

Hannukainen, J C; Lautamäki, R; Mari, A; Pärkkä, J P; Bucci, M; Guzzardi, M A; Kajander, S; Tuokkola, T; Knuuti, J; Iozzo, P

2016-07-01

Insulin resistance, β-cell dysfunction, and ectopic fat deposition have been implicated in the pathogenesis of coronary artery disease (CAD) and type 2 diabetes, which is common in CAD patients. We investigated whether CAD is an independent predictor of these metabolic abnormalities and whether this interaction is influenced by superimposed myocardial ischemia. We studied CAD patients with (n = 8) and without (n = 14) myocardial ischemia and eight non-CAD controls. Insulin sensitivity and secretion and substrate oxidation were measured during fasting and oral glucose tolerance testing. We used magnetic resonance imaging/spectroscopy, positron emission and computerized tomography to characterize CAD, cardiac function, pericardial and abdominal adipose tissue, and myocardial, liver, and pancreatic triglyceride contents. Ischemic CAD was characterized by elevated oxidative glucose metabolism and a proportional decline in β-cell insulin secretion and reduction in lipid oxidation. Cardiac function was preserved in CAD groups, whereas cardiac fat depots were elevated in ischemic CAD compared to non-CAD subjects. Liver and pancreatic fat contents were similar in all groups and related with surrounding adipose masses or systemic insulin sensitivity. In ischemic CAD patients, glucose oxidation is enhanced and correlates inversely with insulin secretion. This can be seen as a mechanism to prevent glucose lowering because glucose is required in oxygen-deprived tissues. On the other hand, the accumulation of cardiac triglycerides may be a physiological adaptation to the limited fatty acid oxidative capacity. Our results underscore the urgent need of clinical trials that define the optimal/safest glycemic range in situations of myocardial ischemia.

Elevated Glucose Oxidation, Reduced Insulin Secretion, and a Fatty Heart May Be Protective Adaptions in Ischemic CAD

PubMed Central

Hannukainen, J. C.; Lautamäki, R.; Mari, A.; Pärkkä, J. P.; Bucci, M.; Guzzardi, M. A.; Kajander, S.; Tuokkola, T.; Knuuti, J.

2016-01-01

Background: Insulin resistance, β-cell dysfunction, and ectopic fat deposition have been implicated in the pathogenesis of coronary artery disease (CAD) and type 2 diabetes, which is common in CAD patients. We investigated whether CAD is an independent predictor of these metabolic abnormalities and whether this interaction is influenced by superimposed myocardial ischemia. Methods and Results: We studied CAD patients with (n = 8) and without (n = 14) myocardial ischemia and eight non-CAD controls. Insulin sensitivity and secretion and substrate oxidation were measured during fasting and oral glucose tolerance testing. We used magnetic resonance imaging/spectroscopy, positron emission and computerized tomography to characterize CAD, cardiac function, pericardial and abdominal adipose tissue, and myocardial, liver, and pancreatic triglyceride contents. Ischemic CAD was characterized by elevated oxidative glucose metabolism and a proportional decline in β-cell insulin secretion and reduction in lipid oxidation. Cardiac function was preserved in CAD groups, whereas cardiac fat depots were elevated in ischemic CAD compared to non-CAD subjects. Liver and pancreatic fat contents were similar in all groups and related with surrounding adipose masses or systemic insulin sensitivity. Conclusions: In ischemic CAD patients, glucose oxidation is enhanced and correlates inversely with insulin secretion. This can be seen as a mechanism to prevent glucose lowering because glucose is required in oxygen-deprived tissues. On the other hand, the accumulation of cardiac triglycerides may be a physiological adaptation to the limited fatty acid oxidative capacity. Our results underscore the urgent need of clinical trials that define the optimal/safest glycemic range in situations of myocardial ischemia. PMID:27045985

Novel Photochrome Aptamer Switch Assay (PHASA) for adaptive binding to aptamers.

PubMed

Papper, Vladislav; Pokholenko, Oleksandr; Wu, Yuanyuan; Zhou, Yubin; Jianfeng, Ping; Steele, Terry W J; Marks, Robert S

2014-11-01

A novel Photochrome-Aptamer Switch Assay (PHASA) for the detection and quantification of small environmentally important molecules such as toxins, explosives, drugs and pollutants, which are difficult to detect using antibodies-based assays with high sensitivity and specificity, has been developed. The assay is based on the conjugation of a particular stilbene-analyte derivative to any aptamer of interest. A unique feature of the stilbene molecule is its reporting power via trans-cis photoisomerisation (from fluorescent trans-isomer to non-fluorescent cis-isomer) upon irradiation with the excitation light. The resulting fluorescence decay rate for the trans-isomer of the stilbene-analyte depends on viscosity and spatial freedom to rotate in the surrounding medium and can be used to indicate the presence of the analyte. Quantification of the assay is achieved by calibration of the fluorescence decay rate for the amount of the tested analyte. Two different formats of PHASA have been recently developed: direct conjugation and adaptive binding. New stilbene-maleimide derivatives used in the adaptive binding format have been prepared and characterised. They demonstrate effective binding to the model thiol compound and to the thiolated Malachite Green aptamer.

Applicability of a bioelectronic cardiac monitoring system for the detection of biological effects of pollution in bioindicator species in the Gulf of Finland

NASA Astrophysics Data System (ADS)

Kholodkevich, Sergey V.; Kuznetsova, Tatiana V.; Sharov, Andrey N.; Kurakin, Anton S.; Lips, Urmas; Kolesova, Natalia; Lehtonen, Kari K.

2017-07-01

Field testing of an innovative technology based on a bioelectronic cardiac monitoring system was carried out in the Gulf of Finland (Baltic Sea). The study shows that the bioelectronic system is suitable for the selected bivalve mollusks Mytilus trossulus, Macoma balthica and Anodonta anatina. Specimens taken from reference sites demonstrated a heart rate recovery time of < 60 min after testing with changed salinity load, while those collected from sites characterized by high anthropogenic pressure demonstrated a prolonged recovery time of up to 110-360 min. These results make possible a discrimination of the study sites based on the assessment of physiological adaptive capacities of inhabiting species. In addition, the approach of measuring heart rate characteristics in M. balthica transplanted in cages to specific target areas was successfully used to evaluate the decline in the adaptive potential of mollusks exposed at polluted sites. Application of the novel system is a useful tool for the biomonitoring of freshwater and brackish water areas. Development of methodological basis for the testing of adaptive capacities (health) of key aquatic organisms provides new knowledge of biological effects of anthropogenic chemical stress in aquatic organisms.

COULD INTERFERON-GAMMA BE A THERAPEUTIC TARGET FOR TREATING HEART FAILURE?

PubMed Central

Levick, Scott P.; Goldspink, Paul H.

2013-01-01

The cytokine interferon-gamma (IFN-γ), is the only known member of the type II family of interferons, and as such, binds to its own distinct receptor. It is important in host defense against infection, as well as adaptive immune responses. Whilst a wide array of cytokines are known to be involved in adverse remodeling of the heart and the progression to heart failure, the role of IFN-γ is unclear. Recent evidence from clinical studies, animal models of myocarditis and hypertension, as well as isolated cell studies, provide conflicting data as to whether IFN-γ is pathological or protective in the heart. Thus, it is important to highlight these discrepant findings so that areas of future investigation can be identified to more clearly determine the precise role of IFN-γ in the heart. Accordingly, this review will: 1) discuss the source of IFN-γ in the diseased heart; 2) summarize the data from animal studies; 3) discuss the effects of IFN-γ on isolated cardiac fibroblasts and cardiomyocytes; 4) identify signaling mechanisms that may be invoked by IFN-γ in the heart; and 5) present the clinical evidence supporting a role for IFN-γ in heart failure. PMID:23589353

Phosphorylation of the chromatin remodeling factor DPF3a induces cardiac hypertrophy through releasing HEY repressors from DNA.

PubMed

Cui, Huanhuan; Schlesinger, Jenny; Schoenhals, Sophia; Tönjes, Martje; Dunkel, Ilona; Meierhofer, David; Cano, Elena; Schulz, Kerstin; Berger, Michael F; Haack, Timm; Abdelilah-Seyfried, Salim; Bulyk, Martha L; Sauer, Sascha; Sperling, Silke R

2016-04-07

DPF3 (BAF45c) is a member of the BAF chromatin remodeling complex. Two isoforms have been described, namely DPF3a and DPF3b. The latter binds to acetylated and methylated lysine residues of histones. Here, we elaborate on the role of DPF3a and describe a novel pathway of cardiac gene transcription leading to pathological cardiac hypertrophy. Upon hypertrophic stimuli, casein kinase 2 phosphorylates DPF3a at serine 348. This initiates the interaction of DPF3a with the transcriptional repressors HEY, followed by the release of HEY from the DNA. Moreover, BRG1 is bound by DPF3a, and is thus recruited to HEY genomic targets upon interaction of the two components. Consequently, the transcription of downstream targets such as NPPA and GATA4 is initiated and pathological cardiac hypertrophy is established. In human, DPF3a is significantly up-regulated in hypertrophic hearts of patients with hypertrophic cardiomyopathy or aortic stenosis. Taken together, we show that activation of DPF3a upon hypertrophic stimuli switches cardiac fetal gene expression from being silenced by HEY to being activated by BRG1. Thus, we present a novel pathway for pathological cardiac hypertrophy, whose inhibition is a long-term therapeutic goal for the treatment of the course of heart failure. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

Targeted ablation of cardiac sympathetic neurons reduces resting, reflex and exercise-induced sympathetic activation in conscious rats.

PubMed

Lujan, Heidi L; Palani, Gurunanthan; Chen, Ying; Peduzzi, Jean D; Dicarlo, Stephen E

2009-05-01

Cholera toxin B subunit conjugated to saporin (SAP, a ribosomal inactivating protein that binds to and inactivates ribosomes) was injected in both stellate ganglia to evaluate the physiological response to targeted ablation of cardiac sympathetic neurons. Resting cardiac sympathetic activity (cardiac sympathetic tonus), exercise-induced sympathetic activity (heart rate responses to graded exercise), and reflex sympathetic activity (heart rate responses to graded doses of sodium nitroprusside, SNP) were determined in 18 adult conscious Sprague-Dawley male rats. Rats were randomly divided into the following three groups (n = 6/group): 1) control (no injection), 2) bilateral stellate ganglia injection of unconjugated cholera toxin B (CTB), and 3) bilateral stellate ganglia injection of cholera toxin B conjugated to SAP (CTB-SAP). CTB-SAP rats, compared with control and CTB rats, had reduced cardiac sympathetic tonus and reduced heart rate responses to graded exercise and graded doses of SNP. Furthermore, the number of stained neurons in the stellate ganglia and spinal cord (segments T(1)-T(4)) was reduced in CTB-SAP rats. Thus CTB-SAP retrogradely transported from the stellate ganglia is effective at ablating cardiac sympathetic neurons and reducing resting, exercise, and reflex sympathetic activity. Additional studies are required to further characterize the physiological responses to this procedure as well as determine if this new approach is safe and efficacious for the treatment of conditions associated with excess sympathetic activity (e.g., autonomic dysreflexia, hypertension, heart failure, and ventricular arrhythmias).

Evaluation of Cardiac Toxicity Biomarkers in Rats from Different Laboratories.

PubMed

Kim, Kyuri; Chini, Naseem; Fairchild, David G; Engle, Steven K; Reagan, William J; Summers, Sandra D; Mirsalis, Jon C

2016-12-01

There is a great need for improved diagnostic and prognostic accuracy of potential cardiac toxicity in drug development. This study reports the evaluation of several commercially available biomarker kits by 3 institutions (SRI, Eli Lilly, and Pfizer) for the discrimination between myocardial degeneration/necrosis and cardiac hypertrophy as well as the assessment of the interlaboratory and interplatform variation in results. Serum concentrations of natriuretic peptides (N-terminal pro-atrial natriuretic peptide [NT-proANP] and N-terminal pro-brain natriuretic peptide [NT-proBNP]), cardiac and skeletal troponins (cTnI, cTnT, and sTnI), myosin light chain 3 (Myl3), and fatty acid binding protein 3 (FABP3) were assessed in rats treated with minoxidil (MNX) and isoproterenol (ISO). MNX caused increased heart-to-body weight ratios and prominent elevations in NT-proANP and NT-proBNP concentrations detected at 24-hr postdose without elevation in troponins, Myl3, or FABP3 and with no abnormal histopathological findings. ISO caused ventricular leukocyte infiltration, myocyte fibrosis, and necrosis with increased concentrations of the natriuretic peptides, cardiac troponins, and Myl3. These results reinforce the advantages of a multimarker strategy in elucidating the underlying cause of cardiac insult and detecting myocardial tissue damage at 24-hr posttreatment. The interlaboratory and interplatform comparison analyses also showed that the data obtained from different laboratories and platforms are highly correlated and reproducible, making these biomarkers widely applicable in preclinical studies.

An adaptive spatio-temporal Gaussian filter for processing cardiac optical mapping data.

PubMed

Pollnow, S; Pilia, N; Schwaderlapp, G; Loewe, A; Dössel, O; Lenis, G

2018-06-04

Optical mapping is widely used as a tool to investigate cardiac electrophysiology in ex vivo preparations. Digital filtering of fluorescence-optical data is an important requirement for robust subsequent data analysis and still a challenge when processing data acquired from thin mammalian myocardium. Therefore, we propose and investigate the use of an adaptive spatio-temporal Gaussian filter for processing optical mapping signals from these kinds of tissue usually having low signal-to-noise ratio (SNR). We demonstrate how filtering parameters can be chosen automatically without additional user input. For systematic comparison of this filter with standard filtering methods from the literature, we generated synthetic signals representing optical recordings from atrial myocardium of a rat heart with varying SNR. Furthermore, all filter methods were applied to experimental data from an ex vivo setup. Our developed filter outperformed the other filter methods regarding local activation time detection at SNRs smaller than 3 dB which are typical noise ratios expected in these signals. At higher SNRs, the proposed filter performed slightly worse than the methods from literature. In conclusion, the proposed adaptive spatio-temporal Gaussian filter is an appropriate tool for investigating fluorescence-optical data with low SNR. The spatio-temporal filter parameters were automatically adapted in contrast to the other investigated filters. Copyright © 2018 Elsevier Ltd. All rights reserved.

Evolution of Salmonella enterica Virulence via Point Mutations in the Fimbrial Adhesin

PubMed Central

Kisiela, Dagmara I.; Chattopadhyay, Sujay; Libby, Stephen J.; Karlinsey, Joyce E.; Fang, Ferric C.; Tchesnokova, Veronika; Kramer, Jeremy J.; Beskhlebnaya, Viktoriya; Samadpour, Mansour; Grzymajlo, Krzysztof; Ugorski, Maciej; Lankau, Emily W.; Mackie, Roderick I.; Clegg, Steven; Sokurenko, Evgeni V.

2012-01-01

Whereas the majority of pathogenic Salmonella serovars are capable of infecting many different animal species, typically producing a self-limited gastroenteritis, serovars with narrow host-specificity exhibit increased virulence and their infections frequently result in fatal systemic diseases. In our study, a genetic and functional analysis of the mannose-specific type 1 fimbrial adhesin FimH from a variety of serovars of Salmonella enterica revealed that specific mutant variants of FimH are common in host-adapted (systemically invasive) serovars. We have found that while the low-binding shear-dependent phenotype of the adhesin is preserved in broad host-range (usually systemically non-invasive) Salmonella, the majority of host-adapted serovars express FimH variants with one of two alternative phenotypes: a significantly increased binding to mannose (as in S. Typhi, S. Paratyphi C, S. Dublin and some isolates of S. Choleraesuis), or complete loss of the mannose-binding activity (as in S. Paratyphi B, S. Choleraesuis and S. Gallinarum). The functional diversification of FimH in host-adapted Salmonella results from recently acquired structural mutations. Many of the mutations are of a convergent nature indicative of strong positive selection. The high-binding phenotype of FimH that leads to increased bacterial adhesiveness to and invasiveness of epithelial cells and macrophages usually precedes acquisition of the non-binding phenotype. Collectively these observations suggest that activation or inactivation of mannose-specific adhesive properties in different systemically invasive serovars of Salmonella reflects their dynamic trajectories of adaptation to a life style in specific hosts. In conclusion, our study demonstrates that point mutations are the target of positive selection and, in addition to horizontal gene transfer and genome degradation events, can contribute to the differential pathoadaptive evolution of Salmonella. PMID:22685400

Cross-cultural adaptation and psychometric properties of an Arabic language version of the Brief Illness Perception Questionnaire in Lebanon.

PubMed

Saarti, Stéphanie; Jabbour, Hicham; El Osta, Nada; Hajj, Aline; Khabbaz, Lydia Rabbaa

2016-01-01

Patients' positive illness perceptions (IPs) significantly contribute to treatment success. The Brief Illness Perception Questionnaire (Brief IPQ) is widely used in various diseases for assessing IPs. It was developed in English-speaking countries and studies on it in Arab countries are scarce. This observational cross-sectional study aimed to cross-culturally adapt the Brief IPQ English version into a modern Arabic language version and determine its psychometric properties in a sample of Lebanese cardiac disease patients. This study was approved by the Institutional Review Board of Saint Joseph University of Beirut, Lebanon. A convenience sample of 30 patients with cardiac disease were recruited during routine visits to cardiologists' offices in Beirut, Lebanon. Inclusion criteria were at least one cardiac disease for at least 6 months with no acute episode or exacerbation of the disease during the 6 preceding months, age ≥ 18 years, and the ability to read and comprehend Arabic. The pre-final version of the Brief IPQ Arabic version was tested for face and content validity. The meaning, comprehensibility, and acceptability were studied by individual interviews. For discriminant validity and internal consistency of the Brief IPQ Arabic version (Brief IPQ-Ar), 100 patients were recruited in a similar manner using the same inclusion criteria. To assess reproducibility, 30 patients, selected randomly from the 100 patients, filled the questionnaire a second time, 3-4 weeks after its first administration and under the same conditions. Psychometric properties of the Brief IPQ-Ar among Lebanese patients suffering from cardiac diseases. Semantic equivalence between the Brief IPQ-Ar questions and patients' descriptions was 100%. Cronbach's alpha was 0.717, which shows good internal consistency. Reproducibility was satisfactory (ICC values>0.776). Moreover, the Brief IPQ-Ar discriminated participants according to the type of cardiac disease and treatment-related characteristics. We confirm that the Brief IPQ-Ar is appropriate for exploring IPs in cardiac disease patients whose first language is Arabic. Further research should be conducted to test this Arabic version in other types of diseases.

Cross-cultural adaptation and psychometric properties of an Arabic language version of the Brief Illness Perception Questionnaire in Lebanon

PubMed Central

Saarti, Stéphanie; Jabbour, Hicham; El Osta, Nada; Hajj, Aline; Khabbaz, Lydia Rabbaa

2016-01-01

Background Patients’ positive illness perceptions (IPs) significantly contribute to treatment success. The Brief Illness Perception Questionnaire (Brief IPQ) is widely used in various diseases for assessing IPs. It was developed in English-speaking countries and studies on it in Arab countries are scarce. Objectives, Setting and design This observational cross-sectional study aimed to cross-culturally adapt the Brief IPQ English version into a modern Arabic language version and determine its psychometric properties in a sample of Lebanese cardiac disease patients. This study was approved by the Institutional Review Board of Saint Joseph University of Beirut, Lebanon. Participants A convenience sample of 30 patients with cardiac disease were recruited during routine visits to cardiologists’ offices in Beirut, Lebanon. Inclusion criteria were at least one cardiac disease for at least 6 months with no acute episode or exacerbation of the disease during the 6 preceding months, age≥18 years, and the ability to read and comprehend Arabic. The pre-final version of the Brief IPQ Arabic version was tested for face and content validity. The meaning, comprehensibility, and acceptability were studied by individual interviews. For discriminant validity and internal consistency of the Brief IPQ Arabic version (Brief IPQ-Ar), 100 patients were recruited in a similar manner using the same inclusion criteria. To assess reproducibility, 30 patients, selected randomly from the 100 patients, filled the questionnaire a second time, 3–4 weeks after its first administration and under the same conditions. Main outcome measures Psychometric properties of the Brief IPQ-Ar among Lebanese patients suffering from cardiac diseases. Results Semantic equivalence between the Brief IPQ-Ar questions and patients’ descriptions was 100%. Cronbach's alpha was 0.717, which shows good internal consistency. Reproducibility was satisfactory (ICC values>0.776). Moreover, the Brief IPQ-Ar discriminated participants according to the type of cardiac disease and treatment-related characteristics. Conclusions We confirm that the Brief IPQ-Ar is appropriate for exploring IPs in cardiac disease patients whose first language is Arabic. Further research should be conducted to test this Arabic version in other types of diseases. PMID:27282197

Cross-cultural adaptation and psychometric properties of an Arabic language version of the Brief Illness Perception Questionnaire in Lebanon.

PubMed

Saarti, Stéphanie; Jabbour, Hicham; Osta, Nada El; Hajj, Aline; Khabbaz, Lydia Rabbaa

2016-01-01

Background Patients' positive illness perceptions (IPs) significantly contribute to treatment success. The Brief Illness Perception Questionnaire (Brief IPQ) is widely used in various diseases for assessing IPs. It was developed in English-speaking countries and studies on it in Arab countries are scarce. Objectives, Setting and design This observational cross-sectional study aimed to cross-culturally adapt the Brief IPQ English version into a modern Arabic language version and determine its psychometric properties in a sample of Lebanese cardiac disease patients. This study was approved by the Institutional Review Board of Saint Joseph University of Beirut, Lebanon. Participants A convenience sample of 30 patients with cardiac disease were recruited during routine visits to cardiologists' offices in Beirut, Lebanon. Inclusion criteria were at least one cardiac disease for at least 6 months with no acute episode or exacerbation of the disease during the 6 preceding months, age≥18 years, and the ability to read and comprehend Arabic. The pre-final version of the Brief IPQ Arabic version was tested for face and content validity. The meaning, comprehensibility, and acceptability were studied by individual interviews. For discriminant validity and internal consistency of the Brief IPQ Arabic version (Brief IPQ-Ar), 100 patients were recruited in a similar manner using the same inclusion criteria. To assess reproducibility, 30 patients, selected randomly from the 100 patients, filled the questionnaire a second time, 3-4 weeks after its first administration and under the same conditions. Main outcome measures Psychometric properties of the Brief IPQ-Ar among Lebanese patients suffering from cardiac diseases. Results Semantic equivalence between the Brief IPQ-Ar questions and patients' descriptions was 100%. Cronbach's alpha was 0.717, which shows good internal consistency. Reproducibility was satisfactory (ICC values>0.776). Moreover, the Brief IPQ-Ar discriminated participants according to the type of cardiac disease and treatment-related characteristics. Conclusions We confirm that the Brief IPQ-Ar is appropriate for exploring IPs in cardiac disease patients whose first language is Arabic. Further research should be conducted to test this Arabic version in other types of diseases.

A modern approach for epitope prediction: identification of foot-and-mouth disease virus peptides binding bovine leukocyte antigen (BoLA) class I molecules

USDA-ARS?s Scientific Manuscript database

Major histocompatibility complex (MHC) class I molecules regulate adaptive immune responses through the presentation of antigenic peptides to CD8positive T-cells. Polymorphisms in the peptide binding region of class I molecules determine peptide binding affinity and stability during antigen presenta...

The spatial architecture of protein function and adaptation

PubMed Central

McLaughlin, Richard N.; Poelwijk, Frank J.; Raman, Arjun; Gosal, Walraj S.; Ranganathan, Rama

2014-01-01

Statistical analysis of protein evolution suggests a design for natural proteins in which sparse networks of coevolving amino acids (termed sectors) comprise the essence of three-dimensional structure and function1, 2, 3, 4, 5. However, proteins are also subject to pressures deriving from the dynamics of the evolutionary process itself—the ability to tolerate mutation and to be adaptive to changing selection pressures6, 7, 8, 9, 10. To understand the relationship of the sector architecture to these properties, we developed a high-throughput quantitative method for a comprehensive single-mutation study in which every position is substituted individually to every other amino acid. Using a PDZ domain (PSD95pdz3) model system, we show that sector positions are functionally sensitive to mutation, whereas non-sector positions are more tolerant to substitution. In addition, we find that adaptation to a new binding specificity initiates exclusively through variation within sector residues. A combination of just two sector mutations located near and away from the ligand-binding site suffices to switch the binding specificity of PSD95pdz3 quantitatively towards a class-switching ligand. The localization of functional constraint and adaptive variation within the sector has important implications for understanding and engineering proteins. PMID:23041932

Cardiovascular actions of the ghrelin gene-derived peptides and growth hormone-releasing hormone.

PubMed

Granata, Riccarda; Isgaard, Jörgen; Alloatti, Giuseppe; Ghigo, Ezio

2011-05-01

In 1976, small peptide growth hormone secretagogues (GHSs) were discovered and found to promote growth hormone (GH) release from the pituitary. The GHS receptor (GHS-R) was subsequently cloned, and its endogenous ligand ghrelin was later isolated from the stomach. Ghrelin is a 28-amino acid peptide, whose acylation is essential for binding to GHS-R type 1a and for the endocrine functions, including stimulation of GH secretion and subsequent food intake. Unacylated ghrelin, the other ghrelin form, although devoid of GHS-R binding is an active peptide, sharing many peripheral effects with acylated ghrelin (AG). The ghrelin system is broadly expressed in myocardial tissues, where it exerts different functions. Indeed, ghrelin inhibits cardiomyocyte and endothelial cell apoptosis, and improves left ventricular (LV) function during ischemia-reperfusion (I/R) injury. In rats with heart failure (HF), ghrelin improves LV dysfunction and attenuates the development of cardiac cachexia. Similarly, ghrelin exerts vasodilatory effects in humans, improves cardiac function and decreases systemic vascular resistance in patients with chronic HF. Obestatin is a recently identified ghrelin gene peptide. The physiological role of obestatin and its binding to the putative GPR39 receptor are still unclear, although protective effects have been demonstrated in the pancreas and heart. Similarly to AG, the hypothalamic peptide growth hormone-releasing hormone (GHRH) stimulates GH release from the pituitary, through binding to the GHRH-receptor. Besides its proliferative effects in different cell types, at the cardiovascular level GHRH inhibits cardiomyocyte apoptosis, and reduces infarct size in both isolated rat heart after I/R and in vivo after myocardial infarction. Therefore, both ghrelin and GHRH exert cardioprotective effects, which make them candidate targets for therapeutic intervention in cardiovascular dysfunctions.

Ginseng gintonin activates the human cardiac delayed rectifier K+ channel: involvement of Ca2+/calmodulin binding sites.

PubMed

Choi, Sun-Hye; Lee, Byung-Hwan; Kim, Hyeon-Joong; Jung, Seok-Won; Kim, Hyun-Sook; Shin, Ho-Chul; Lee, Jun-Hee; Kim, Hyoung-Chun; Rhim, Hyewhon; Hwang, Sung-Hee; Ha, Tal Soo; Kim, Hyun-Ji; Cho, Hana; Nah, Seung-Yeol

2014-09-01

Gintonin, a novel, ginseng-derived G protein-coupled lysophosphatidic acid (LPA) receptor ligand, elicits [Ca(2+)]i transients in neuronal and non-neuronal cells via pertussis toxin-sensitive and pertussis toxin-insensitive G proteins. The slowly activating delayed rectifier K(+) (I(Ks)) channel is a cardiac K(+) channel composed of KCNQ1 and KCNE1 subunits. The C terminus of the KCNQ1 channel protein has two calmodulin-binding sites that are involved in regulating I(Ks) channels. In this study, we investigated the molecular mechanisms of gintonin-mediated activation of human I(Ks) channel activity by expressing human I(Ks) channels in Xenopus oocytes. We found that gintonin enhances IKs channel currents in concentration- and voltage-dependent manners. The EC50 for the I(Ks) channel was 0.05 ± 0.01 μg/ml. Gintonin-mediated activation of the I(Ks) channels was blocked by an LPA1/3 receptor antagonist, an active phospholipase C inhibitor, an IP3 receptor antagonist, and the calcium chelator BAPTA. Gintonin-mediated activation of both the I(Ks) channel was also blocked by the calmodulin (CaM) blocker calmidazolium. Mutations in the KCNQ1 [Ca(2+)]i/CaM-binding IQ motif sites (S373P, W392R, or R539W)blocked the action of gintonin on I(Ks) channel. However, gintonin had no effect on hERG K(+) channel activity. These results show that gintonin-mediated enhancement of I(Ks) channel currents is achieved through binding of the [Ca(2+)]i/CaM complex to the C terminus of KCNQ1 subunit.

Qiliqiangxin inhibits the development of cardiac hypertrophy, remodeling, and dysfunction during 4 weeks of pressure overload in mice.

PubMed

Zou, Yunzeng; Lin, Li; Ye, Yong; Wei, Jianming; Zhou, Ning; Liang, Yanyan; Gong, Hui; Li, Lei; Wu, Jian; Li, Yunbo; Jia, Zhenhua; Wu, Yiling; Zhou, Jingmin; Ge, Junbo

2012-03-01

Qiliqiangxin (QL), a traditional Chinese medicine, has been used in the treatment of chronic heart failure. However, whether QL can benefit cardiac remodeling in the hypertensive state is unknown. We here examined the effects of QL on the development of cardiac hypertrophy through comparing those of losartan in C57BL/6 mice underlying transverse aorta constriction for 4 weeks. QL and losartan were administrated at 0.6 mg and 13.4 mg·kg·d, respectively. Cardiac hypertrophy, function, and remodeling were evaluated by echocardiography, catheterization, histology, and examination of specific gene expression and ERK phosphorylation. Cardiac apoptosis, autophagy, tumor necrosis factor α/insulin-like growth factor-1, and angiotensin II type 1 receptor expression and especially the proliferation of cardiomyocytes and phosphorylation of ErbB receptors were examined in vivo to elucidate the mechanisms. Transverse aorta constriction for 2 weeks resulted in a significant cardiac hypertrophy, which was significantly suppressed by either QL or losartan treatment. At 4 weeks after transverse aorta constriction, although the development of cardiac dysfunction and remodeling and the increases in apoptosis, autophagy, tumor necrosis factor α/insulin-like growth factor-1, and angiotensin II type 1 receptor expression were abrogated comparably between QL and losartan treatments, QL, but not losartan, enhanced proliferation of cardiomyocytes, which was paralleled with dowregulation of CCAAT/enhancer-binding protein β, upregulation of CBP/p300-interacting transactivator with ED-rich carboxy-terminal domain 4, and increases in ErbB2 and ErbB4 phosphorylation. Furthermore, inhibition of either ErbB2 or CBP/p300-interacting transactivator with ED-rich carboxy-terminal domain 4 abolished the cardiac protective effects of QL. Thus, QL inhibits myocardial inflammation and cardiomyocyte death and promotes cardiomyocyte proliferation, leading to an ameliorated cardiac remodeling and function in a mouse model of pressure overload. The possible mechanisms may involve inhibition of angiotensin II type 1 receptor and activation of ErbB receptors.

Analysis of the microRNA signature in left atrium from patients with valvular heart disease reveals their implications in atrial fibrillation.

PubMed

Doñate Puertas, Rosa; Jalabert, Audrey; Meugnier, Emmanuelle; Euthine, Vanessa; Chevalier, Philippe; Rome, Sophie

2018-01-01

Among the potential factors which may contribute to the development and perpetuation of atrial fibrillation, dysregulation of miRNAs has been suggested. Thus in this study, we have quantified the basal expressions of 662 mature human miRNAs in left atrium (LA) from patients undergoing cardiac surgery for valve repair, suffering or not from atrial fibrillation (AF) by using TaqMan® Low Density arrays (v2.0). Among the 299 miRNAs expressed in all patients, 42 miRNAs had altered basal expressions in patients with AF. Binding-site predictions with Targetscan (conserved sites among species) indicated that the up- and down-regulated miRNAs controlled respectively 3,310 and 5,868 genes. To identify the most relevant cellular functions under the control of the altered miRNAs, we focused on the 100 most targeted genes of each list and identified 5 functional protein-protein networks among these genes. Up-regulated networks were involved in synchronisation of circadian rythmicity and in the control of the AKT/PKC signaling pathway (i.e., proliferation/adhesion). Down-regulated networks were the IGF-1 pathway and TGF-beta signaling pathway and a network involved in RNA-mediated gene silencing, suggesting for the first time that alteration of miRNAs in AF would also perturbate the whole miRNA machinery. Then we crossed the list of miRNA predicted genes, and the list of mRNAs altered in similar patients suffering from AF and we found that respectively 44.5% and 55% of the up- and down-regulated mRNA are predicted to be conserved targets of the altered miRNAs (at least one binding site in 3'-UTR). As they were involved in the same biological processes mentioned above, these data demonstrated that a great part of the transcriptional defects previously published in LA from AF patients are likely due to defects at the post-transcriptional level and involved the miRNAs. Our stringent analysis permitted us to identify highly targeted protein-protein networks under the control of miRNAs in LA and, among them, to highlight those specifically affected in AF patients with altered miRNA signature. Further studies are now required to determine whether alterations of miRNA levels in AF pathology are causal or represent an adaptation to prevent cardiac electrical and structural remodeling.

Bioimpedance cardiography in pregnancy: A longitudinal cohort study on hemodynamic pattern and outcome.

PubMed

Andreas, Martin; Kuessel, Lorenz; Kastl, Stefan P; Wirth, Stefan; Gruber, Kathrin; Rhomberg, Franziska; Gomari-Grisar, Fatemeh A; Franz, Maximilian; Zeisler, Harald; Gottsauner-Wolf, Michael

2016-06-01

Pregnancy associated cardiovascular pathologies have a significant impact on outcome for mother and child. Bioimpedance cardiography may provide additional outcome-relevant information early in pregnancy and may also be used as a predictive instrument for pregnancy-associated diseases. We performed a prospective longitudinal cohort trial in an outpatient setting and included 242 pregnant women. Cardiac output and concomitant hemodynamic data were recorded from 11(th)-13(th) week of gestation every 5(th) week as well as at two occasions post partum employing bioimpedance cardiography. Cardiac output increased during pregnancy and peaked early in the third trimester. A higher heart rate and a decreased systemic vascular resistance were accountable for the observed changes. Women who had a pregnancy-associated disease during a previous pregnancy or developed hypertension or preeclampsia had a significantly increased cardiac output early in pregnancy. Furthermore, an effect of cardiac output on birthweight was found in healthy pregnancies and could be confirmed with multiple linear regression analysis. Cardiovascular adaptation during pregnancy is characterized by distinct pattern described herein. These may be altered in women at risk for preeclampsia or reduced birthweigth. The assessment of cardiac parameters by bioimpedance cardiography could be performed at low costs without additional risks.

Implementation study of an analog spiking neural network for assisting cardiac delay prediction in a cardiac resynchronization therapy device.

PubMed

Sun, Qing; Schwartz, François; Michel, Jacques; Herve, Yannick; Dalmolin, Renzo

2011-06-01

In this paper, we aim at developing an analog spiking neural network (SNN) for reinforcing the performance of conventional cardiac resynchronization therapy (CRT) devices (also called biventricular pacemakers). Targeting an alternative analog solution in 0.13- μm CMOS technology, this paper proposes an approach to improve cardiac delay predictions in every cardiac period in order to assist the CRT device to provide real-time optimal heartbeats. The primary analog SNN architecture is proposed and its implementation is studied to fulfill the requirement of very low energy consumption. By using the Hebbian learning and reinforcement learning algorithms, the intended adaptive CRT device works with different functional modes. The simulations of both learning algorithms have been carried out, and they were shown to demonstrate the global functionalities. To improve the realism of the system, we introduce various heart behavior models (with constant/variable heart rates) that allow pathologic simulations with/without noise on the signals of the input sensors. The simulations of the global system (pacemaker models coupled with heart models) have been investigated and used to validate the analog spiking neural network implementation.

Transition from metabolic adaptation to maladaptation of the heart in obesity: role of apelin.

PubMed

Alfarano, C; Foussal, C; Lairez, O; Calise, D; Attané, C; Anesia, R; Daviaud, D; Wanecq, E; Parini, A; Valet, P; Kunduzova, O

2015-02-01

Impaired energy metabolism is the defining characteristic of obesity-related heart failure. The adipocyte-derived peptide apelin has a role in the regulation of cardiovascular and metabolic homeostasis and may contribute to the link between obesity, energy metabolism and cardiac function. Here we investigate the role of apelin in the transition from metabolic adaptation to maladaptation of the heart in obese state. Adult male C57BL/6J, apelin knock-out (KO) or wild-type mice were fed a high-fat diet (HFD) for 18 weeks. To induce heart failure, mice were subjected to pressure overload after 18 weeks of HFD. Long-term effects of apelin on fatty acid (FA) oxidation, glucose metabolism, cardiac function and mitochondrial changes were evaluated in HFD-fed mice after 4 weeks of pressure overload. Cardiomyocytes from HFD-fed mice were isolated for analysis of metabolic responses. In HFD-fed mice, pressure overload-induced transition from hypertrophy to heart failure is associated with reduced FA utilization (P<0.05), accelerated glucose oxidation (P<0.05) and mitochondrial damage. Treatment of HFD-fed mice with apelin for 4 weeks prevented pressure overload-induced decline in FA metabolism (P<0.05) and mitochondrial defects. Furthermore, apelin treatment lowered fasting plasma glucose (P<0.01), improved glucose tolerance (P<0.05) and preserved cardiac function (P<0.05) in HFD-fed mice subjected to pressure overload. In apelin KO HFD-fed mice, spontaneous cardiac dysfunction is associated with reduced FA oxidation (P<0.001) and increased glucose oxidation (P<0.05). In isolated cardiomyocytes, apelin stimulated FA oxidation in a dose-dependent manner and this effect was prevented by small interfering RNA sirtuin 3 knockdown. These data suggest that obesity-related decline in cardiac function is associated with defective myocardial energy metabolism and mitochondrial abnormalities. Furthermore, our work points for therapeutic potential of apelin to prevent myocardial metabolic abnormalities in heart failure paired with obesity.

Determinants of glycan receptor specificity of H2N2 influenza A virus hemagglutinin.

PubMed

Viswanathan, Karthik; Koh, Xiaoying; Chandrasekaran, Aarthi; Pappas, Claudia; Raman, Rahul; Srinivasan, Aravind; Shriver, Zachary; Tumpey, Terrence M; Sasisekharan, Ram

2010-10-29

The H2N2 subtype of influenza A virus was responsible for the Asian pandemic of 1957-58. However, unlike other subtypes that have caused pandemics such as H1N1 and H3N2, which continue to circulate among humans, H2N2 stopped circulating in the human population in 1968. Strains of H2 subtype still continue to circulate in birds and occasionally pigs and could be reintroduced into the human population through antigenic drift or shift. Such an event is a potential global health concern because of the waning population immunity to H2 hemagglutinin (HA). The first step in such a cross-species transmission and human adaptation of influenza A virus is the ability for its surface glycoprotein HA to bind to glycan receptors expressed in the human upper respiratory epithelia. Recent structural and biochemical studies have focused on understanding the glycan receptor binding specificity of the 1957-58 pandemic H2N2 HA. However, there has been considerable HA sequence divergence in the recent avian-adapted H2 strains from the pandemic H2N2 strain. Using a combination of structural modeling, quantitative glycan binding and human respiratory tissue binding methods, we systematically identify mutations in the HA from a recent avian-adapted H2N2 strain (A/Chicken/PA/2004) that make its quantitative glycan receptor binding affinity (defined using an apparent binding constant) comparable to that of a prototypic pandemic H2N2 (A/Albany/6/58) HA.

Determinants of Glycan Receptor Specificity of H2N2 Influenza A Virus Hemagglutinin

PubMed Central

Chandrasekaran, Aarthi; Pappas, Claudia; Raman, Rahul; Srinivasan, Aravind; Shriver, Zachary; Tumpey, Terrence M.; Sasisekharan, Ram

2010-01-01

The H2N2 subtype of influenza A virus was responsible for the Asian pandemic of 1957-58. However, unlike other subtypes that have caused pandemics such as H1N1 and H3N2, which continue to circulate among humans, H2N2 stopped circulating in the human population in 1968. Strains of H2 subtype still continue to circulate in birds and occasionally pigs and could be reintroduced into the human population through antigenic drift or shift. Such an event is a potential global health concern because of the waning population immunity to H2 hemagglutinin (HA). The first step in such a cross-species transmission and human adaptation of influenza A virus is the ability for its surface glycoprotein HA to bind to glycan receptors expressed in the human upper respiratory epithelia. Recent structural and biochemical studies have focused on understanding the glycan receptor binding specificity of the 1957-58 pandemic H2N2 HA. However, there has been considerable HA sequence divergence in the recent avian-adapted H2 strains from the pandemic H2N2 strain. Using a combination of structural modeling, quantitative glycan binding and human respiratory tissue binding methods, we systematically identify mutations in the HA from a recent avian-adapted H2N2 strain (A/Chicken/PA/2004) that make its quantitative glycan receptor binding affinity (defined using an apparent binding constant) comparable to that of a prototypic pandemic H2N2 (A/Albany/6/58) HA. PMID:21060797

MicroRNA-155 attenuates late sepsis-induced cardiac dysfunction through JNK and β-arrestin 2.

PubMed

Zhou, Yu; Song, Yan; Shaikh, Zahir; Li, Hui; Zhang, Haiju; Caudle, Yi; Zheng, Shouhua; Yan, Hui; Hu, Dan; Stuart, Charles; Yin, Deling

2017-07-18

Cardiac dysfunction is correlated with detrimental prognosis of sepsis and contributes to a high risk of mortality. After an initial hyperinflammatory reaction, most patients enter a protracted state of immunosuppression (late sepsis) that alters both innate and adaptive immunity. The changes of cardiac function in late sepsis are not yet known. MicroRNA-155 (miR-155) is previously found to play important roles in both regulations of immune activation and cardiac function. In this study, C57BL/6 mice were operated to develop into early and late sepsis phases, and miR-155 mimic was injected through the tail vein 48 h after cecal ligation and puncture (CLP). The effect of miR-155 on CLP-induced cardiac dysfunction was explored in late sepsis. We found that increased expression of miR-155 in the myocardium protected against cardiac dysfunction in late sepsis evidenced by attenuating sepsis-reduced cardiac output and enhancing left ventricular systolic function. We also observed that miR-155 markedly reduced the infiltration of macrophages and neutrophils into the myocardium and attenuated the inflammatory response via suppression of JNK signaling pathway. Moreover, overexpression of β-arrestin 2 (Arrb2) exacerbated the mice mortality and immunosuppression in late sepsis. Furthermore, transfection of miR-155 mimic reduced Arrb2 expression, and then restored immunocompetence and improved survival in late septic mice. We conclude that increased miR-155 expression through systemic administration of miR-155 mimic attenuates cardiac dysfunction and improves late sepsis survival by targeting JNK associated inflammatory signaling and Arrb2 mediated immunosuppression.

Excessive training induces molecular signs of pathologic cardiac hypertrophy.

PubMed

da Rocha, Alisson L; Teixeira, Giovana R; Pinto, Ana P; de Morais, Gustavo P; Oliveira, Luciana da C; de Vicente, Larissa Gaioto; da Silva, Lilian E C M; Pauli, José R; Cintra, Dennys E; Ropelle, Eduardo R; de Moura, Leandro P; Mekary, Rania A; de Freitas, Ellen C; da Silva, Adelino S R

2018-05-24

Chronic exercise induces cardiac remodeling that promotes left ventricular hypertrophy and cardiac functional improvement, which are mediated by the mammalian or the mechanistic target of rapamycin (mTOR) as well as by the androgen and glucocorticoid receptors (GRs). However, pathological conditions (i.e., chronic heart failure, hypertension, and aortic stenosis, etc.) also induce cardiac hypertrophy, but with detrimental function, high levels of proinflammatory cytokines and myostatin, elevated fibrosis, reduced adenosine monophosphate-activated protein kinase (AMPK) activation, and fetal gene reactivation. Furthermore, recent studies have evidenced that excessive training induced an inflammatory status in the serum, muscle, hypothalamus, and liver, suggesting a pathological condition that could also be detrimental to cardiac tissue. Here, we verified the effects of three running overtraining (OT) models on the molecular parameters related to physiological and pathological cardiac hypertrophy. C57BL/6 mice performed three different OT protocols and were evaluated for molecular parameters related to physiological and pathological cardiac hypertrophy, including immunoblotting, reverse transcription polymerase chain reaction, histology, and immunohistochemistry analyses. In summary, the three OT protocols induced left ventricle (LV) hypertrophy with signs of cardiac fibrosis and negative morphological adaptations. These maladaptations were accompanied by reductions in AMPKalpha (Thr172) phosphorylation, androgen receptor, and GR expressions, as well as by an increase in interleukin-6 expression. Specifically, the downhill running-based OT model reduced the content of some proteins related to the mTOR signaling pathway and upregulated the β-isoform of myosin heavy-chain gene expression, presenting signs of LV pathological hypertrophy development. © 2018 Wiley Periodicals, Inc.

β-Arrestin2 Improves Post-Myocardial Infarction Heart Failure via Sarco(endo)plasmic Reticulum Ca2+-ATPase-Dependent Positive Inotropy in Cardiomyocytes.

PubMed

McCrink, Katie A; Maning, Jennifer; Vu, Angela; Jafferjee, Malika; Marrero, Christine; Brill, Ava; Bathgate-Siryk, Ashley; Dabul, Samalia; Koch, Walter J; Lymperopoulos, Anastasios

2017-11-01

Heart failure is the leading cause of death in the Western world, and new and innovative treatments are needed. The GPCR (G protein-coupled receptor) adapter proteins βarr (β-arrestin)-1 and βarr-2 are functionally distinct in the heart. βarr1 is cardiotoxic, decreasing contractility by opposing β 1 AR (adrenergic receptor) signaling and promoting apoptosis/inflammation post-myocardial infarction (MI). Conversely, βarr2 inhibits apoptosis/inflammation post-MI but its effects on cardiac function are not well understood. Herein, we sought to investigate whether βarr2 actually increases cardiac contractility. Via proteomic investigations in transgenic mouse hearts and in H9c2 rat cardiomyocytes, we have uncovered that βarr2 directly interacts with SERCA2a (sarco[endo]plasmic reticulum Ca 2+ -ATPase) in vivo and in vitro in a β 1 AR-dependent manner. This interaction causes acute SERCA2a SUMO (small ubiquitin-like modifier)-ylation, increasing SERCA2a activity and thus, cardiac contractility. βarr1 lacks this effect. Moreover, βarr2 does not desensitize β 1 AR cAMP-dependent procontractile signaling in cardiomyocytes, again contrary to βarr1. In vivo, post-MI heart failure mice overexpressing cardiac βarr2 have markedly improved cardiac function, apoptosis, inflammation, and adverse remodeling markers, as well as increased SERCA2a SUMOylation, levels, and activity, compared with control animals. Notably, βarr2 is capable of ameliorating cardiac function and remodeling post-MI despite not increasing cardiac βAR number or cAMP levels in vivo. In conclusion, enhancement of cardiac βarr2 levels/signaling via cardiac-specific gene transfer augments cardiac function safely, that is, while attenuating post-MI remodeling. Thus, cardiac βarr2 gene transfer might be a novel, safe positive inotropic therapy for both acute and chronic post-MI heart failure. © 2017 American Heart Association, Inc.

Grundvoraussetzungen herzchirurgischer Einheiten zur Behandlung von Patienten mit angeborenen Herzfehlern.

PubMed

2016-01-01

This document defines fundamental structures of congenital cardiac surgery departments in Germany. It has been developed by the executive boards of the German Society for Thoracic and Cardiovascular Surgery (GSTCVS) and the German Society of Pediatric Cardiology (GSPC) in collaboration with the working group for Congenital and Pediatric Heart Surgery of the GSTCVS.This updated consensus paper is based on a previous publication of the European Association for Cardiothoracic Surgery (EACTS) and is a refinement and adaptation of its initial version published by the GSTCVS in 2005. In Germany, pediatric cardiology and cardiac surgery facilities caring for patients with congenital cardiac defects are subject to certain regulations. For example, in 2010 the Federal Joint Committee implemented the resolution on Quality Assurance Measures in the Provision of Cardiac Surgical Care for Children and Adolescents (directive congenital cardiac surgery) which regulates structural and process quality compulsorily. To date, fundamental and considerable differences of the respective departments persist.Congenital cardiac surgery departments have to provide the whole spectrum of the cardiac surgical therapy from the neonate to the adult with congenital cardiac defects (with the exception of heart transplantation) continuously and with the appropriate experience. Furthermore, the departments have to prove their constant scientific activity and ensure that they facilitate education and training for the specialty certification in cardiac surgery. The responsible surgeons of all congenital cardiac surgery departments commit to participate in the currently voluntary national quality assurance for congenital cardiac defects of the GSTCVS and the GSPC and perform an individual surgical outcome assessment and risk stratification. This is supplemented by the willingness for external certification specific to the individual and the facilitation of peer review procedures for quality assurance purposes. Additional measures, such as collaboration in clinical research and ongoing interdisciplinary education and training, are preferable. Georg Thieme Verlag KG Stuttgart · New York.

Lung Structure and the Intrinsic Challenges of Gas Exchange.

PubMed

Hsia, Connie C W; Hyde, Dallas M; Weibel, Ewald R

2016-03-15

Structural and functional complexities of the mammalian lung evolved to meet a unique set of challenges, namely, the provision of efficient delivery of inspired air to all lung units within a confined thoracic space, to build a large gas exchange surface associated with minimal barrier thickness and a microvascular network to accommodate the entire right ventricular cardiac output while withstanding cyclic mechanical stresses that increase several folds from rest to exercise. Intricate regulatory mechanisms at every level ensure that the dynamic capacities of ventilation, perfusion, diffusion, and chemical binding to hemoglobin are commensurate with usual metabolic demands and periodic extreme needs for activity and survival. This article reviews the structural design of mammalian and human lung, its functional challenges, limitations, and potential for adaptation. We discuss (i) the evolutionary origin of alveolar lungs and its advantages and compromises, (ii) structural determinants of alveolar gas exchange, including architecture of conducting bronchovascular trees that converge in gas exchange units, (iii) the challenges of matching ventilation, perfusion, and diffusion and tissue-erythrocyte and thoracopulmonary interactions. The notion of erythrocytes as an integral component of the gas exchanger is emphasized. We further discuss the signals, sources, and limits of structural plasticity of the lung in alveolar hypoxia and following a loss of lung units, and the promise and caveats of interventions aimed at augmenting endogenous adaptive responses. Our objective is to understand how individual components are matched at multiple levels to optimize organ function in the face of physiological demands or pathological constraints. Copyright © 2016 John Wiley & Sons, Inc.

SIGNALLING THROUGH RETINOIC ACID RECEPTORS IN CARDIAC DEVELOPMENT: DOING THE RIGHT THINGS AT THE RIGHT TIMES

PubMed Central

Xavier-Neto, José; Costa, Ângela M. Sousa; Figueira, Ana Carolina M.; Caiaffa, Carlo Donato; do Amaral, Fabio Neves; Peres, Lara Maldanis Cerqueira; da Silva, Bárbara Santos Pires; Santos, Luana Nunes; Moise, Alexander R.; Castillo, Hozana Andrade

2015-01-01

Retinoic acid (RA) is a terpenoid that is synthesized from Vitamin A/retinol (ROL) and binds to the nuclear receptors retinoic acid receptor (RAR)/retinoid X receptor (RXR) to control multiple developmental processes in vertebrates. The available clinic and experimental data provide uncontested evidence for the pleiotropic roles of RA signalling in development of multiple embryonic structures and organs such eyes, central nervous system, gonads, lungs and heart. The development of any of these above-mentioned embryonic organ systems can be effectively utilized to showcase the many strategies utilized by RA signalling. However, it is very likely that the strategies employed to transfer RA signals during cardiac development comprise the majority of the relevant and sophisticated ways through which retinoid signals can be conveyed in a complex biological system. Here, we provide the reader with arguments indicating that RA signalling is exquisitely regulated according to specific phases of cardiac development and that RA signalling itself is one of the major regulators of the timing of cardiac morphogenesis and differentiation. We will focus on the role of signalling by RA receptors (RARs) in early phases of heart development. PMID:25134739

An anti-PDGFRβ aptamer for selective delivery of small therapeutic peptide to cardiac cells.

PubMed

Romanelli, Alessandra; Affinito, Alessandra; Avitabile, Concetta; Catuogno, Silvia; Ceriotti, Paola; Iaboni, Margherita; Modica, Jessica; Condorelli, Geroloma; Catalucci, Daniele

2018-01-01

Small therapeutic peptides represent a promising field for the treatment of pathologies such as cardiac diseases. However, the lack of proper target-selective carriers hampers their translation towards a potential clinical application. Aptamers are cell-specific carriers that bind with high affinity to their specific target. However, some limitations on their conjugation to small peptides and the functionality of the resulting aptamer-peptide chimera exist. Here, we generated a novel aptamer-peptide chimera through conjugation of the PDGFRβ-targeting Gint4.T aptamer to MP, a small mimetic peptide that via targeting of the Cavβ2 subunit of the L-type calcium channel (LTCC) can recover myocardial function in pathological heart conditions associated with defective LTCC function. The conjugation reaction was performed by click chemistry in the presence of N,N,N',N',N"-pentamethyldiethylenetriamine as a Cu (I) stabilizing agent in a DMSO-free aqueous buffer. When administered to cardiac cells, the Gint4.T-MP aptamer-peptide chimera was successfully internalized in cells, allowing the functional targeting of MP to LTCC. This approach represents the first example of the use of an internalizing aptamer for selective delivery of a small therapeutic peptide to cardiac cells.

Cardiac function adaptations in hibernating grizzly bears (Ursus arctos horribilis).

PubMed

Nelson, O Lynne; Robbins, Charles T

2010-03-01

Research on the cardiovascular physiology of hibernating mammals may provide insight into evolutionary adaptations; however, anesthesia used to handle wild animals may affect the cardiovascular parameters of interest. To overcome these potential biases, we investigated the functional cardiac phenotype of the hibernating grizzly bear (Ursus arctos horribilis) during the active, transitional and hibernating phases over a 4 year period in conscious rather than anesthetized bears. The bears were captive born and serially studied from the age of 5 months to 4 years. Heart rate was significantly different from active (82.6 +/- 7.7 beats/min) to hibernating states (17.8 +/- 2.8 beats/min). There was no difference from the active to the hibernating state in diastolic and stroke volume parameters or in left atrial area. Left ventricular volume:mass was significantly increased during hibernation indicating decreased ventricular mass. Ejection fraction of the left ventricle was not different between active and hibernating states. In contrast, total left atrial emptying fraction was significantly reduced during hibernation (17.8 +/- 2.8%) as compared to the active state (40.8 +/- 1.9%). Reduced atrial chamber function was also supported by reduced atrial contraction blood flow velocities and atrial contraction ejection fraction during hibernation; 7.1 +/- 2.8% as compared to 20.7 +/- 3% during the active state. Changes in the diastolic cardiac filling cycle, especially atrial chamber contribution to ventricular filling, appear to be the most prominent macroscopic functional change during hibernation. Thus, we propose that these changes in atrial chamber function constitute a major adaptation during hibernation which allows the myocardium to conserve energy, avoid chamber dilation and remain healthy during a period of extremely low heart rates. These findings will aid in rational approaches to identifying underlying molecular mechanisms.

Translation, Cross-cultural Adaptation and Psychometric Validation of the Korean-Language Cardiac Rehabilitation Barriers Scale (CRBS-K)

PubMed Central

2017-01-01

Objective To perform a translation and cross-cultural adaptation of the Cardiac Rehabilitation Barriers Scale (CRBS) for use in Korea, followed by psychometric validation. The CRBS was developed to assess patients' perception of the degree to which patient, provider and health system-level barriers affect their cardiac rehabilitation (CR) participation. Methods The CRBS consists of 21 items (barriers to adherence) rated on a 5-point Likert scale. The first phase was to translate and cross-culturally adapt the CRBS to the Korean language. After back-translation, both versions were reviewed by a committee. The face validity was assessed in a sample of Korean patients (n=53) with history of acute myocardial infarction that did not participate in CR through semi-structured interviews. The second phase was to assess the construct and criterion validity of the Korean translation as well as internal reliability, through administration of the translated version in 104 patients, principle component analysis with varimax rotation and cross-referencing against CR use, respectively. Results The length, readability, and clarity of the questionnaire were rated well, demonstrating face validity. Analysis revealed a six-factor solution, demonstrating construct validity. Cronbach's alpha was greater than 0.65. Barriers rated highest included not knowing about CR and not being contacted by a program. The mean CRBS score was significantly higher among non-attendees (2.71±0.26) than CR attendees (2.51±0.18) (p<0.01). Conclusion The Korean version of CRBS has demonstrated face, content and criterion validity, suggesting it may be useful for assessing barriers to CR utilization in Korea. PMID:29201826

Potential adverse cardiac remodelling in highly trained athletes: still unknown clinical significance.

PubMed

Gabrielli, Luigi; Sitges, Marta; Chiong, Mario; Jalil, Jorge; Ocaranza, María; Llevaneras, Silvana; Herrera, Sebastian; Fernandez, Rodrigo; Saavedra, Rodrigo; Yañez, Fernando; Vergara, Luis; Diaz, Alexis; Lavandero, Sergio; Castro, Pablo

2018-06-12

Moderate endurance exercise has long been considered an essential element to maintain cardiovascular health, and sedentary behaviour in the general population has been related to a significant increase in all-causes of mortality, cardiovascular disease mortality and cardiovascular disease incidence. However, a growing group of people performs an intense exercise that leads to multiple heart adaptive changes that are collectively called "athlete's heart". In this review, we discussed the evidence of cardiac remodelling process secondary to repetitive and strenuous exercise in some predisposed athletes that produces intense and probably deleterious changes in cardiac morphology and function with no clear clinical significance in long-term follow-up. Moreover, we also discussed the individual biological response to exercise assessed by myocardial damage, inflammation, oxidative stress, fibrosis and ventricular hypertrophy biomarkers showing different intensities with equivalent exertion.

Efficient solution of ordinary differential equations modeling electrical activity in cardiac cells.

PubMed

Sundnes, J; Lines, G T; Tveito, A

2001-08-01

The contraction of the heart is preceded and caused by a cellular electro-chemical reaction, causing an electrical field to be generated. Performing realistic computer simulations of this process involves solving a set of partial differential equations, as well as a large number of ordinary differential equations (ODEs) characterizing the reactive behavior of the cardiac tissue. Experiments have shown that the solution of the ODEs contribute significantly to the total work of a simulation, and there is thus a strong need to utilize efficient solution methods for this part of the problem. This paper presents how an efficient implicit Runge-Kutta method may be adapted to solve a complicated cardiac cell model consisting of 31 ODEs, and how this solver may be coupled to a set of PDE solvers to provide complete simulations of the electrical activity.

New pyrimido-indole compound CD-160130 preferentially inhibits the KV11.1B isoform and produces antileukemic effects without cardiotoxicity.

PubMed

Gasparoli, Luca; D'Amico, Massimo; Masselli, Marika; Pillozzi, Serena; Caves, Rachel; Khuwaileh, Rawan; Tiedke, Wolfgang; Mugridge, Kenneth; Pratesi, Alessandro; Mitcheson, John S; Basso, Giuseppe; Becchetti, Andrea; Arcangeli, Annarosa

2015-02-01

KV11.1 (hERG1) channels are often overexpressed in human cancers. In leukemias, KV11.1 regulates pro-survival signals that promote resistance to chemotherapy, raising the possibility that inhibitors of KV11.1 could be therapeutically beneficial. However, because of the role of KV11.1 in cardiac repolarization, blocking these channels may cause cardiac arrhythmias. We show that CD-160130, a novel pyrimido-indole compound, blocks KV11.1 channels with a higher efficacy for the KV11.1 isoform B, in which the IC50 (1.8 μM) was approximately 10-fold lower than observed in KV11.1 isoform A. At this concentration, CD-160130 also had minor effects on Kir2.1, KV 1.3, Kv1.5, and KCa3.1. In vitro, CD-160130 induced leukemia cell apoptosis, and could overcome bone marrow mesenchymal stromal cell (MSC)-induced chemoresistance. This effect was caused by interference with the survival signaling pathways triggered by MSCs. In vivo, CD-160130 produced an antileukemic activity, stronger than that caused by cytarabine. Consistent with its atypical target specificity, CD-160130 did not bind to the main binding site of the arrhythmogenic KV11.1 blockers (the Phe656 pore residue). Importantly, in guinea pigs CD-160130 produced neither alteration of the cardiac action potential shape in dissociated cardiomyocytes nor any lengthening of the QT interval in vivo. Moreover, CD-160130 had no myelotoxicity on human bone marrow-derived cells. Therefore, CD-160130 is a promising first-in-class compound to attempt oncologic therapy without cardiotoxicity, based on targeting KV11.1. Because leukemia and cardiac cells tend to express different ratios of the A and B KV11.1 isoforms, the pharmacological properties of CD-160130 may depend, at least in part, on isoform specificity. Copyright © 2014 by The American Society for Pharmacology and Experimental Therapeutics.

Long-Term Simulated Microgravity Causes Cardiac RyR2 Phosphorylation and Arrhythmias in Mice

PubMed Central

Respress, Jonathan L.; Gershovich, Pavel M.; Wang, Tiannan; Reynolds, Julia O.; Skapura, Darlene G.; Sutton, Jeffrey P.; Miyake, Christina Y.; Wehrens, Xander H.T.

2014-01-01

Background Long-term exposure to microgravity during space flight may lead to cardiac remodeling and rhythm disturbances. In mice, hindlimb unloading (HU) mimics the effects of microgravity and stimulates physiological adaptations, including cardiovascular deconditioning. Recent studies have demonstrated an important role played by changes in intracellular Ca handling in the pathogenesis of heart failure and arrhythmia. In this study, we tested the hypothesis that cardiac remodeling following HU in mice involves abnormal intracellular Ca regulation through the cardiac ryanodine receptor (RyR2). Methods and Results Mice were subjected to HU by tail suspension for 28 to 56 days in order to induce cardiac remodeling (n=15). Control mice (n=19) were treated equally, with the exception of tail suspension. Echocardiography revealed cardiac enlargement and depressed contractility starting at 28 days post-HU versus control. Moreover, mice were more susceptible to pacing-induced ventricular arrhythmias after HU. Ventricular myocytes isolated from HU mice exhibited an increased frequency of spontaneous sarcoplasmic reticulum (SR) Ca release events and enhanced SR Ca leak via RyR2. Western blotting revealed increased RyR2 phosphorylation at S2814, and increased CaMKII auto-phosphorylation at T287, suggesting that CaMKII activation of RyR2 might underlie enhanced SR Ca release in HU mice. Conclusion These data suggest that abnormal intracellular Ca handling, likely due to increased CaMKII phosphorylation of RyR2, plays a role in cardiac remodeling following simulated microgravity in mice. PMID:25227892

Statistical coding and decoding of heartbeat intervals.

PubMed

Lucena, Fausto; Barros, Allan Kardec; Príncipe, José C; Ohnishi, Noboru

2011-01-01

The heart integrates neuroregulatory messages into specific bands of frequency, such that the overall amplitude spectrum of the cardiac output reflects the variations of the autonomic nervous system. This modulatory mechanism seems to be well adjusted to the unpredictability of the cardiac demand, maintaining a proper cardiac regulation. A longstanding theory holds that biological organisms facing an ever-changing environment are likely to evolve adaptive mechanisms to extract essential features in order to adjust their behavior. The key question, however, has been to understand how the neural circuitry self-organizes these feature detectors to select behaviorally relevant information. Previous studies in computational perception suggest that a neural population enhances information that is important for survival by minimizing the statistical redundancy of the stimuli. Herein we investigate whether the cardiac system makes use of a redundancy reduction strategy to regulate the cardiac rhythm. Based on a network of neural filters optimized to code heartbeat intervals, we learn a population code that maximizes the information across the neural ensemble. The emerging population code displays filter tuning proprieties whose characteristics explain diverse aspects of the autonomic cardiac regulation, such as the compromise between fast and slow cardiac responses. We show that the filters yield responses that are quantitatively similar to observed heart rate responses during direct sympathetic or parasympathetic nerve stimulation. Our findings suggest that the heart decodes autonomic stimuli according to information theory principles analogous to how perceptual cues are encoded by sensory systems.

Mechanism of HSV infection through soluble adapter-mediated virus bridging to the EGF receptor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakano, Kenji, E-mail: kenakano@med.kyushu-u.ac.j; Kobayashi, Masatoshi; Nakamura, Kei-ichiro

2011-04-25

Herpes simplex virus entry into cells requires the binding of envelope glycoprotein D (gD) to an entry receptor. Depending on the cell, entry occurs by different mechanisms, including fusion at the cell surface or endocytosis. Here we examined the entry mechanism through a non-HSV receptor mediated by a soluble bi-specific adapter protein composed of recognition elements for gD and the EGF receptor (EGFR). Virus entered into endosomes using either EGF or an EGFR-specific single chain antibody (scFv) for receptor recognition. Infection was less efficient with the EGF adapter which could be attributed to its weaker binding to a viral gD.more » Infection mediated by the scFv adapter was pH sensitive, indicating that gD-EGFR bridging alone was insufficient for capsid release from endosomes. We also show that the scFv adapter enhanced infection of EGFR-expressing tumor tissue in vivo. Our results indicate that adapters may retarget HSV infection without drastically changing the entry mechanism.« less

Exercise-Induced Changes in Glucose Metabolism Promote Physiological Cardiac Growth

PubMed Central

Gibb, Andrew A.; Epstein, Paul N.; Uchida, Shizuka; Zheng, Yuting; McNally, Lindsey A.; Obal, Detlef; Katragadda, Kartik; Trainor, Patrick; Conklin, Daniel J.; Brittian, Kenneth R.; Tseng, Michael T.; Wang, Jianxun; Jones, Steven P.; Bhatnagar, Aruni

2017-01-01

Background: Exercise promotes metabolic remodeling in the heart, which is associated with physiological cardiac growth; however, it is not known whether or how physical activity–induced changes in cardiac metabolism cause myocardial remodeling. In this study, we tested whether exercise-mediated changes in cardiomyocyte glucose metabolism are important for physiological cardiac growth. Methods: We used radiometric, immunologic, metabolomic, and biochemical assays to measure changes in myocardial glucose metabolism in mice subjected to acute and chronic treadmill exercise. To assess the relevance of changes in glycolytic activity, we determined how cardiac-specific expression of mutant forms of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase affect cardiac structure, function, metabolism, and gene programs relevant to cardiac remodeling. Metabolomic and transcriptomic screenings were used to identify metabolic pathways and gene sets regulated by glycolytic activity in the heart. Results: Exercise acutely decreased glucose utilization via glycolysis by modulating circulating substrates and reducing phosphofructokinase activity; however, in the recovered state following exercise adaptation, there was an increase in myocardial phosphofructokinase activity and glycolysis. In mice, cardiac-specific expression of a kinase-deficient 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase transgene (GlycoLo mice) lowered glycolytic rate and regulated the expression of genes known to promote cardiac growth. Hearts of GlycoLo mice had larger myocytes, enhanced cardiac function, and higher capillary-to-myocyte ratios. Expression of phosphatase-deficient 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase in the heart (GlycoHi mice) increased glucose utilization and promoted a more pathological form of hypertrophy devoid of transcriptional activation of the physiological cardiac growth program. Modulation of phosphofructokinase activity was sufficient to regulate the glucose–fatty acid cycle in the heart; however, metabolic inflexibility caused by invariantly low or high phosphofructokinase activity caused modest mitochondrial damage. Transcriptomic analyses showed that glycolysis regulates the expression of key genes involved in cardiac metabolism and remodeling. Conclusions: Exercise-induced decreases in glycolytic activity stimulate physiological cardiac remodeling, and metabolic flexibility is important for maintaining mitochondrial health in the heart. PMID:28860122

Long Noncoding RNA (lncRNA) n379519 Promotes Cardiac Fibrosis in Post-Infarct Myocardium by Targeting miR-30.

PubMed

Wang, Xiaxia; Yong, Chunming; Yu, Kai; Yu, Renchao; Zhang, Rui; Yu, Lingfan; Li, Shan; Cai, Shanglang

2018-06-11

BACKGROUND Abnormally expressed long noncoding RNAs (lncRNAs) are recognized as one of the key causes of cardiac diseases. However, the role of lncRNA in cardiac fibrosis remains largely unknown. MATERIAL AND METHODS The experiment was divided into 4 groups: a sham operation group, a myocardial infarction (MI) group, a lentivirus group (LV-si-n379519), and a lentivirus control (LV-NC) group. The adenovirus expression vectors LV-si-n379519 and LV-NC were constructed and transfected into mice. Echocardiography, HE staining, and Masson staining were performed to detect the heart function and collagen volume fraction in each group. RT-PCR was used to detect the expression level of n379519, miR-30, collagen I, and collagen III. In vitro, cardiac fibroblasts (CFs) were cultured and the relationship between n379519 and miR-30 was verified using luciferase reporter vector, n379519 siRNA, and miR-30 inhibitor. RESULTS The expression of n379519 was markedly upregulated in the hearts of mice with MI and in the fibrotic CFs. Knockdown of endogenous n379519 by its siRNA improved the heart function and reduced collagen deposition and the process of cardiac fibrosis. Further experiments showed the opposite trend of expression between n379519 and miR-30. Bioinformatics analysis and luciferase reporter assay indicated that n379519 directly binds to miR-30. Moreover, miR-30 inhibitor abrogated the collagen synthesis inhibition induced by n379519. CONCLUSIONS These findings reveal a novel function of n379519-miR-30 axis as a negative regulator for the treatment of MI-induced cardiac fibrosis and the associated cardiac dysfunction.

Protein Kinase A (PKA) Phosphorylation of Shp2 Protein Inhibits Its Phosphatase Activity and Modulates Ligand Specificity

PubMed Central

Burmeister, Brian T.; Wang, Li; Gold, Matthew G.; Skidgel, Randal A.; O'Bryan, John P.; Carnegie, Graeme K.

2015-01-01

Pathological cardiac hypertrophy (an increase in cardiac mass resulting from stress-induced cardiac myocyte growth) is a major factor underlying heart failure. Src homology 2 domain-containing phosphatase (Shp2) is critical for cardiac function because mutations resulting in loss of Shp2 catalytic activity are associated with congenital cardiac defects and hypertrophy. We identified a novel mechanism of Shp2 inhibition that may promote cardiac hypertrophy. We demonstrate that Shp2 is a component of the protein kinase A anchoring protein (AKAP)-Lbc complex. AKAP-Lbc facilitates PKA phosphorylation of Shp2, which inhibits Shp2 phosphatase activity. We identified two key amino acids in Shp2 that are phosphorylated by PKA. Thr-73 contributes a helix cap to helix αB within the N-terminal SH2 domain of Shp2, whereas Ser-189 occupies an equivalent position within the C-terminal SH2 domain. Utilizing double mutant PKA phosphodeficient (T73A/S189A) and phosphomimetic (T73D/S189D) constructs, in vitro binding assays, and phosphatase activity assays, we demonstrate that phosphorylation of these residues disrupts Shp2 interaction with tyrosine-phosphorylated ligands and inhibits its protein-tyrosine phosphatase activity. Overall, our data indicate that AKAP-Lbc integrates PKA and Shp2 signaling in the heart and that AKAP-Lbc-associated Shp2 activity is reduced in hypertrophic hearts in response to chronic β-adrenergic stimulation and PKA activation. Therefore, although induction of cardiac hypertrophy is a multifaceted process, inhibition of Shp2 activity through AKAP-Lbc-anchored PKA is a previously unrecognized mechanism that may promote this compensatory response. PMID:25802336

Protein Kinase A (PKA) Phosphorylation of Shp2 Protein Inhibits Its Phosphatase Activity and Modulates Ligand Specificity.

PubMed

Burmeister, Brian T; Wang, Li; Gold, Matthew G; Skidgel, Randal A; O'Bryan, John P; Carnegie, Graeme K

2015-05-08

Pathological cardiac hypertrophy (an increase in cardiac mass resulting from stress-induced cardiac myocyte growth) is a major factor underlying heart failure. Src homology 2 domain-containing phosphatase (Shp2) is critical for cardiac function because mutations resulting in loss of Shp2 catalytic activity are associated with congenital cardiac defects and hypertrophy. We identified a novel mechanism of Shp2 inhibition that may promote cardiac hypertrophy. We demonstrate that Shp2 is a component of the protein kinase A anchoring protein (AKAP)-Lbc complex. AKAP-Lbc facilitates PKA phosphorylation of Shp2, which inhibits Shp2 phosphatase activity. We identified two key amino acids in Shp2 that are phosphorylated by PKA. Thr-73 contributes a helix cap to helix αB within the N-terminal SH2 domain of Shp2, whereas Ser-189 occupies an equivalent position within the C-terminal SH2 domain. Utilizing double mutant PKA phosphodeficient (T73A/S189A) and phosphomimetic (T73D/S189D) constructs, in vitro binding assays, and phosphatase activity assays, we demonstrate that phosphorylation of these residues disrupts Shp2 interaction with tyrosine-phosphorylated ligands and inhibits its protein-tyrosine phosphatase activity. Overall, our data indicate that AKAP-Lbc integrates PKA and Shp2 signaling in the heart and that AKAP-Lbc-associated Shp2 activity is reduced in hypertrophic hearts in response to chronic β-adrenergic stimulation and PKA activation. Therefore, although induction of cardiac hypertrophy is a multifaceted process, inhibition of Shp2 activity through AKAP-Lbc-anchored PKA is a previously unrecognized mechanism that may promote this compensatory response. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

mTOR Hyperactivation by Ablation of Tuberous Sclerosis Complex 2 in the Mouse Heart Induces Cardiac Dysfunction with the Increased Number of Small Mitochondria Mediated through the Down-Regulation of Autophagy

PubMed Central

Taneike, Manabu; Nishida, Kazuhiko; Omiya, Shigemiki; Zarrinpashneh, Elham; Misaka, Tomofumi; Kitazume-Taneike, Rika; Austin, Ruth; Takaoka, Minoru; Yamaguchi, Osamu; Gambello, Michael J.; Shah, Ajay M.; Otsu, Kinya

2016-01-01

Mammalian target of rapamycin complex 1 (mTORC1) is a key regulator of cell growth, proliferation and metabolism. mTORC1 regulates protein synthesis positively and autophagy negatively. Autophagy is a major system to manage bulk degradation and recycling of cytoplasmic components and organelles. Tuberous sclerosis complex (TSC) 1 and 2 form a heterodimeric complex and inactivate Ras homolog enriched in brain, resulting in inhibition of mTORC1. Here, we investigated the effects of hyperactivation of mTORC1 on cardiac function and structure using cardiac-specific TSC2-deficient (TSC2-/-) mice. TSC2-/- mice were born normally at the expected Mendelian ratio. However, the median life span of TSC2-/- mice was approximately 10 months and significantly shorter than that of control mice. TSC2-/- mice showed cardiac dysfunction and cardiomyocyte hypertrophy without considerable fibrosis, cell infiltration or apoptotic cardiomyocyte death. Ultrastructural analysis of TSC2-/- hearts revealed misalignment, aggregation and a decrease in the size and an increase in the number of mitochondria, but the mitochondrial function was maintained. Autophagic flux was inhibited, while the phosphorylation level of S6 or eukaryotic initiation factor 4E -binding protein 1, downstream of mTORC1, was increased. The upregulation of autophagic flux by trehalose treatment attenuated the cardiac phenotypes such as cardiac dysfunction and structural abnormalities of mitochondria in TSC2-/- hearts. The results suggest that autophagy via the TSC2-mTORC1 signaling pathway plays an important role in maintenance of cardiac function and mitochondrial quantity and size in the heart and could be a therapeutic target to maintain mitochondrial homeostasis in failing hearts. PMID:27023784

Structural characterization of metal binding to a cold-adapted frataxin.

PubMed

Noguera, Martín E; Roman, Ernesto A; Rigal, Juan B; Cousido-Siah, Alexandra; Mitschler, André; Podjarny, Alberto; Santos, Javier

2015-06-01

Frataxin is an evolutionary conserved protein that participates in iron metabolism. Deficiency of this small protein in humans causes a severe neurodegenerative disease known as Friedreich's ataxia. A number of studies indicate that frataxin binds iron and regulates Fe-S cluster biosynthesis. Previous structural studies showed that metal binding occurs mainly in a region of high density of negative charge. However, a comprehensive characterization of the binding sites is required to gain further insights into the mechanistic details of frataxin function. In this work, we have solved the X-ray crystal structures of a cold-adapted frataxin from a psychrophilic bacterium in the presence of cobalt or europium ions. We have identified a number of metal-binding sites, mainly solvent exposed, several of which had not been observed in previous studies on mesophilic homologues. No major structural changes were detected upon metal binding, although the structures exhibit significant changes in crystallographic B-factors. The analysis of these B-factors, in combination with crystal packing and RMSD among structures, suggests the existence of localized changes in the internal motions. Based on these results, we propose that bacterial frataxins possess binding sites of moderate affinity for a quick capture and transfer of iron to other proteins and for the regulation of Fe-S cluster biosynthesis, modulating interactions with partner proteins.

North American ginseng (Panax quinquefolius) suppresses β-adrenergic-dependent signalling, hypertrophy, and cardiac dysfunction.

PubMed

Tang, Xilan; Gan, Xiaohong Tracey; Rajapurohitam, Venkatesh; Huang, Cathy Xiaoling; Xue, Jenny; Lui, Edmund M K; Karmazyn, Morris

2016-12-01

There is increasing evidence for a beneficial effect of ginseng on cardiac pathology. Here, we determined whether North American ginseng can modulate the deleterious effects of the β-adrenoceptor agonist isoproterenol on cardiac hypertrophy and function using in vitro and in vivo approaches. Isoproterenol was administered for 2 weeks at either 25 mg/kg per day or 50 mg/kg per day (ISO25 or ISO50) via a subcutaneously implanted osmotic mini-pump to either control rats or those receiving ginseng (0.9 g/L in the drinking water ad libitum). Isoproterenol produced time- and dose-dependent left ventricular dysfunction, although these effects were attenuated by ginseng. Improved cardiac functions were associated with reduced heart masses, as well as prevention in the upregulation of the hypertrophy-related fetal gene expression. Lung masses were similarly attenuated, suggesting reduced pulmonary congestion. In in vitro studies, ginseng (10 μg/mL) completely suppressed the hypertrophic response to 1 μmol/L isoproterenol in terms of myocyte surface area, as well as reduction in the upregulation of fetal gene expression. These effects were associated with attenuation in both protein kinase A and cAMP response element-binding protein phosphorylation. Ginseng attenuates adverse cardiac adrenergic responses and, therefore, may be an effective therapy to reduce hypertrophy and heart failure associated with excessive catecholamine production.

Lamina-associated polypeptide 2alpha loss impairs heart function and stress response in mice.

PubMed

Gotic, Ivana; Leschnik, Michael; Kolm, Ursula; Markovic, Mato; Haubner, Bernhard J; Biadasiewicz, Katarzyna; Metzler, Bernhard; Stewart, Colin L; Foisner, Roland

2010-02-05

Lamina-associated polypeptide (LAP)2alpha is a mammalian chromatin-binding protein that interacts with a fraction of A-type lamins in the nuclear interior. Because mutations in lamins and LAP2alpha lead to cardiac disorders in humans, we hypothesized that these factors may play important roles in heart development and adult tissue homeostasis. We asked whether the presence of LAP2alpha was required for normal cardiac function. To study the molecular mechanisms of the disease, we analyzed heart structure and function in complete and conditional Lap2alpha(-/-) mice as well as Lap2alpha(-/-)/Mdx mutants. Unlike conditional deletion of LAP2alpha in late embryonic striated muscle, its complete knockout caused systolic dysfunction in young mice, accompanied by sporadic fibrosis in old animals, as well as deregulation of major cardiac transcription factors GATA4 and myocyte enhancer factor 2c. Activation of compensatory pathways, including downregulation of beta-adrenergic receptor signaling, resulted in reduced responsiveness of the myocardium to chronic beta-adrenergic stimulation and stalled the progression of LAP2alpha-deficient hearts from hypertrophy toward cardiac failure. Dystrophin deficiency in an Mdx background resulted in a transient rescue of the Lap2alpha(-/-) phenotype. Our data suggest a novel role of LAP2alpha in the maintenance of cardiac function under normal and stress conditions.

RhoA Regulation of Cardiomyocyte Differentiation

PubMed Central

Kaarbø, Mari; Crane, Denis I.; Murrell, Wayne G.

2013-01-01

Earlier findings from our laboratory implicated RhoA in heart developmental processes. To investigate factors that potentially regulate RhoA expression, RhoA gene organisation and promoter activity were analysed. Comparative analysis indicated strict conservation of both gene organisation and coding sequence of the chick, mouse, and human RhoA genes. Bioinformatics analysis of the derived promoter region of mouse RhoA identified putative consensus sequence binding sites for several transcription factors involved in heart formation and organogenesis generally. Using luciferase reporter assays, RhoA promoter activity was shown to increase in mouse-derived P19CL6 cells that were induced to differentiate into cardiomyocytes. Overexpression of a dominant negative mutant of mouse RhoA (mRhoAN19) blocked this cardiomyocyte differentiation of P19CL6 cells and led to the accumulation of the cardiac transcription factors SRF and GATA4 and the early cardiac marker cardiac α-actin. Taken together, these findings indicate a fundamental role for RhoA in the differentiation of cardiomyocytes. PMID:23935420

Development of a Culturally-Adapted Graphic Novella about Emergency Communication: Collaborations with a Limited English Speaking Chinese Immigrant Community.

PubMed

Eisenberg, Devora; Seino, Lena; Meischke, Hendrika; Tu, Shin-Ping; Turner, Anne M; Ike, Brooke; Painter, Ian; Yip, Mei-Po

2016-01-01

Bystander CPR doubles survival from cardiac arrest but limited English proficient (LEP) individuals face barriers calling 911 and performing CPR. Previous training increases the chance that an individual will perform CPR, yet access to classes in non-English speaking populations is limited. We used a cultural adaptation approach to develop a graphic novella for Chinese LEP immigrants about how to call 911 and perform bystander CPR. Collaboration with members of this community occurred through all stages of novella development. One hundred and thirty-two LEP Chinese adults read the novella and answered a survey measuring behavioral intentions. All respondents stated they would call 911 after witnessing a person's collapse, but those previously trained in CPR were more likely to say that they would perform CPR. All participants indicated that they would recommend this novella to others. Developing culturally-responsive evidence-based interventions is necessary to reduce disproportionate death and disability from cardiac arrest in LEP communities.

Molecular Bases of cyclodextrin Adapter Interactions with Engineered Protein Nanopores

DOE Office of Scientific and Technical Information (OSTI.GOV)

Banerjee, A.; Mikhailova, E; Cheley, S

2010-01-01

Engineered protein pores have several potential applications in biotechnology: as sensor elements in stochastic detection and ultrarapid DNA sequencing, as nanoreactors to observe single-molecule chemistry, and in the construction of nano- and micro-devices. One important class of pores contains molecular adapters, which provide internal binding sites for small molecules. Mutants of the {alpha}-hemolysin ({alpha}HL) pore that bind the adapter {beta}-cyclodextrin ({beta}CD) {approx}10{sup 4} times more tightly than the wild type have been obtained. We now use single-channel electrical recording, protein engineering including unnatural amino acid mutagenesis, and high-resolution x-ray crystallography to provide definitive structural information on these engineered protein nanoporesmore » in unparalleled detail.« less

Investigation of light-induced conformation changes in spiropyran-modified succinylated poly(L-lysine).

PubMed

Cooper, T M; Stone, M O; Natarajan, L V; Crane, R L

1995-08-01

To determine the maximum range of coupling between side-chain photochromism and polypeptide conformation change, we modified the carboxylate side chains of succinylated poly(L-lysine) with a spiropyran to form polypeptide I. The extent of modification was determined to be 35.5%. The spacer group length between the polypeptide alpha-carbon and the dye was 12 atoms, providing minimum polypeptide-dye interaction. Conformation changes were monitored by circular dichroism as a function of light adaptation and solvent composition (hexafluoroisopropanol [HFIP] vs trifluoroethanol [TFE]). Under all solvent compositions, the dark-adapted dye was in the merocyanine form. Light adaptation by visible light converted the dye to the spiropyran form. When dissolved in TFE, I adopted a helical conformation insensitive to light adaptation. With increasing percentage HFIP, a solvent-induced helix-to-coil transition was observed around 80% (vol/vol) HFIP. At 100% HFIP, both light- and dark-adapted forms of I were in the coil state. Near the midpoint of the solvent-induced helix-to-coil transition, light adaptation caused conformation changes. Applying helix-to-coil transition theory, we measured a statistically significant difference in coil segment-HFIP binding constant for light- vs dark-adapted solutions (6.38 +/- 0.03 M-1 vs 6.56 +/- 0.03 M-1), but not for the nucleation parameter sigma (1.2 +/- 0.4 10(-3) vs 1.3 +/- 0.3 x 10(-3). The small binding constant difference translated to a light-induced binding energy difference of 17 cal/mol/monomer. Near the midpoint of the helix-to-coil transition, collective interactions between monomer units made possible the translation of a small energy difference (less than RT) into large macromolecular conformation changes.(ABSTRACT TRUNCATED AT 250 WORDS)

FK506-Binding Protein 22 from a Psychrophilic Bacterium, a Cold Shock-Inducible Peptidyl Prolyl Isomerase with the Ability to Assist in Protein Folding

PubMed Central

Budiman, Cahyo; Koga, Yuichi; Takano, Kazufumi; Kanaya, Shigenori

2011-01-01

Adaptation of microorganisms to low temperatures remains to be fully elucidated. It has been previously reported that peptidyl prolyl cis-trans isomerases (PPIases) are involved in cold adaptation of various microorganisms whether they are hyperthermophiles, mesophiles or phsycrophiles. The rate of cis-trans isomerization at low temperatures is much slower than that at higher temperatures and may cause problems in protein folding. However, the mechanisms by which PPIases are involved in cold adaptation remain unclear. Here we used FK506-binding protein 22, a cold shock protein from the psychrophilic bacterium Shewanella sp. SIB1 (SIB1 FKBP22) as a model protein to decipher the involvement of PPIases in cold adaptation. SIB1 FKBP22 is homodimer that assumes a V-shaped structure based on a tertiary model. Each monomer consists of an N-domain responsible for dimerization and a C-catalytic domain. SIB1 FKBP22 is a typical cold-adapted enzyme as indicated by the increase of catalytic efficiency at low temperatures, the downward shift in optimal temperature of activity and the reduction in the conformational stability. SIB1 FKBP22 is considered as foldase and chaperone based on its ability to catalyze refolding of a cis-proline containing protein and bind to a folding intermediate protein, respectively. The foldase and chaperone activites of SIB1 FKBP22 are thought to be important for cold adaptation of Shewanella sp. SIB1. These activities are also employed by other PPIases for being involved in cold adaptation of various microorganisms. Despite other biological roles of PPIases, we proposed that foldase and chaperone activities of PPIases are the main requirement for overcoming the cold-stress problem in microorganisms due to folding of proteins. PMID:21954357

G protein, phosphorylated-GATA4 and VEGF expression in the hearts of transgenic mice overexpressing β1- and β2-adrenergic receptors

PubMed Central

Tae, Hyun-Jin; Petrashevskaya, Natalia; Kim, In Hye; Park, Joon Ha; Lee, Jae-Chul; Won, Moo-Ho; Kim, Yang Hee; Ahn, Ji Hyeon; Park, Jinseu; Choi, Soo Young; Jeon, Yong Hwan

2017-01-01

β1- and β2-adrenergic receptors (ARs) regulate cardiac contractility, calcium handling and protein phosphorylation. The present study aimed to examine the expression levels of vascular endothelial growth factor A (VEGF-A) and several G proteins, and the phosphorylation of transcription factor GATA binding protein 4 (GATA4), by western blot analysis, using isolated hearts from 6 month-old transgenic (TG) mice that overexpress β1AR or β2AR. Cardiac contractility/relaxation and heart rate was increased in both β1AR TG and β2AR TG mouse hearts compared with wild type; however, no significant differences were observed between the β1- and β2AR TG mouse hearts. Protein expression levels of inhibitory guanine nucleotide-binding protein (Gi) 2, Gi3 and G-protein-coupled receptor kinase 2 were upregulated in both TG mice, although the upregulation of Gi2 was more prominent in the β2AR TG mice. VEGF-A expression levels were also increased in both TG mice, and were highest in the β1AR TG mice. In addition, the levels of phosphorylated-GATA4 expression were increased in β1- and β2AR TG mice. In conclusion, the present study demonstrated that cardiac contractility/relaxation and heart rate is increased in β1AR TG and β2AR TG mice, and indicated that this increase may be related to the overexpression of G proteins and G-protein-associated proteins. PMID:28487987

The A31P missense mutation in cardiac myosin binding protein C alters protein structure but does not cause haploinsufficiency.

PubMed

van Dijk, Sabine J; Bezold Kooiker, Kristina; Mazzalupo, Stacy; Yang, Yuanzhang; Kostyukova, Alla S; Mustacich, Debbie J; Hoye, Elaine R; Stern, Joshua A; Kittleson, Mark D; Harris, Samantha P

2016-07-01

Mutations in MYBPC3, the gene encoding cardiac myosin binding protein C (cMyBP-C), are a major cause of hypertrophic cardiomyopathy (HCM). While most mutations encode premature stop codons, missense mutations causing single amino acid substitutions are also common. Here we investigated effects of a single proline for alanine substitution at amino acid 31 (A31P) in the C0 domain of cMyBP-C, which was identified as a natural cause of HCM in cats. Results using recombinant proteins showed that the mutation disrupted C0 structure, altered sensitivity to trypsin digestion, and reduced recognition by an antibody that preferentially recognizes N-terminal domains of cMyBP-C. Western blots detecting A31P cMyBP-C in myocardium of cats heterozygous for the mutation showed a reduced amount of A31P mutant protein relative to wild-type cMyBP-C, but the total amount of cMyBP-C was not different in myocardium from cats with or without the A31P mutation indicating altered rates of synthesis/degradation of A31P cMyBP-C. Also, the mutant A31P cMyBP-C was properly localized in cardiac sarcomeres. These results indicate that reduced protein expression (haploinsufficiency) cannot account for effects of the A31P cMyBP-C mutation and instead suggest that the A31P mutation causes HCM through a poison polypeptide mechanism that disrupts cMyBP-C or myocyte function. Copyright © 2016 Elsevier Inc. All rights reserved.

Mapping the ER Interactome: The P Domains of Calnexin and Calreticulin as Plurivalent Adapters for Foldases and Chaperones.

PubMed

Kozlov, Guennadi; Muñoz-Escobar, Juliana; Castro, Karla; Gehring, Kalle

2017-09-05

The lectin chaperones calreticulin (CRT) and calnexin (CNX) contribute to the folding of glycoproteins in the ER by recruiting foldases such as the protein disulfide isomerase ERp57 and the peptidyl prolyl cis-trans isomerase CypB. Recently, CRT was shown to interact with the chaperone ERp29. Here, we show that ERp29 directly binds to the P domain of CNX. Crystal structures of the D domain of ERp29 in complex with the P domains from CRT and calmegin, a tissue-specific CNX homolog, reveal a commonality in the mechanism of binding whereby the tip of the P domain functions as a plurivalent adapter to bind a variety of folding factors. We show that mutation of a single residue, D348 in CNX, abrogates binding to ERp29 as well as ERp57 and CypB. The structural diversity of the accessory factors suggests that these chaperones became specialized for glycoprotein folding through convergent evolution of their P-domain binding sites. Copyright © 2017 Elsevier Ltd. All rights reserved.

Molecular beacons for DNA binding proteins: an emerging technology for detection of DNA binding proteins and their ligands.

PubMed

Dummitt, Benjamin; Chang, Yie-Hwa

2006-06-01

Quantitation of the level or activity of specific proteins is one of the most commonly performed experiments in biomedical research. Protein detection has historically been difficult to adapt to high throughput platforms because of heavy reliance upon antibodies for protein detection. Molecular beacons for DNA binding proteins is a recently developed technology that attempts to overcome such limitations. Protein detection is accomplished using inexpensive, easy-to-synthesize oligonucleotides, accompanied by a fluorescence readout. Importantly, detection of the protein and reporting of the signal occur simultaneously, allowing for one-step protocols and increased potential for use in high throughput analysis. While the initial iteration of the technology allowed only for the detection of sequence-specific DNA binding proteins, more recent adaptations allow for the possibility of development of beacons for any protein, independent of native DNA binding activity. Here, we discuss the development of the technology, the mechanism of the reaction, and recent improvements and modifications made to improve the assay in terms of sensitivity, potential for multiplexing, and broad applicability.

Measure of synchrony in the activity of intrinsic cardiac neurons

PubMed Central

Longpré, Jean-Philippe; Salavatian, Siamak; Beaumont, Eric; Armour, J. Andrew; Ardell, Jeffrey L.; Jacquemet, Vincent

2014-01-01

Recent multielectrode array recordings in ganglionated plexi of canine atria have opened the way to the study of population dynamics of intrinsic cardiac neurons. These data provide critical insights into the role of local processing that these ganglia play in the regulation of cardiac function. Low firing rates, marked non-stationarity, interplay with the cardiovascular and pulmonary systems and artifacts generated by myocardial activity create new constraints not present in brain recordings for which almost all neuronal analysis techniques have been developed. We adapted and extended the jitter-based synchrony index (SI) to (1) provide a robust and computationally-efficient tool for assessing the level and statistical significance of SI between cardiac neurons, (2) estimate the bias on SI resulting from neuronal activity possibly hidden in myocardial artifacts, (3) quantify the synchrony or anti-synchrony between neuronal activity and the phase in the cardiac and respiratory cycles. The method was validated on firing time series from a total of 98 individual neurons identified in 8 dog experiments. SI ranged from −0.14 to 0.66, with 23 pairs of neurons with SI>0.1. The estimated bias due to artifacts was typically < 1%. Strongly cardiovascular- and pulmonary-related neurons (SI>0.5) were found. Results support the use of jitter-based synchrony index in the context of intrinsic cardiac neurons. PMID:24621585

Ca2+-Calmodulin and PIP2 interactions at the proximal C-terminus of Kv7 channels.

PubMed

Tobelaim, William S; Dvir, Meidan; Lebel, Guy; Cui, Meng; Buki, Tal; Peretz, Asher; Marom, Milit; Haitin, Yoni; Logothetis, Diomedes E; Hirsch, Joel A; Attali, Bernard

2017-11-02

In the heart, co-assembly of Kv7.1 with KCNE1 produces the slow I KS potassium current, which repolarizes the cardiac action potential and mutations in human Kv7.1 and KCNE1 genes cause cardiac arrhythmias. The proximal Kv7.1 C-terminus binds calmodulin (CaM) and phosphatidylinositol-4,5-bisphosphate (PIP 2 ) and recently we revealed the competition of PIP 2 with the calcified CaM N-lobe to a previously unidentified site in Kv7.1 helix B, also known to harbor a LQT mutation. Data indicated that PIP 2 and Ca 2+ -CaM perform the same function on I KS channel gating to stabilize the channel open state. Here we show that similar features were observed for Kv7.1 currents expressed alone. We also find that conservation of homologous residues in helix B of other Kv7 subtypes confer similar competition of Ca 2+ -CaM with PIP2 binding to their proximal C-termini and suggest that PIP2-CaM interactions converge to Kv7 helix B to modulates channel activity in a Kv7 subtype-dependent manner.

FKBP12.6 protects heart from AngII-induced hypertrophy through inhibiting Ca2+ /calmodulin-mediated signalling pathways in vivo and in vitro.

PubMed

Xiao, Yun-Fei; Zeng, Zhi-Xiong; Guan, Xiao-Hui; Wang, Ling-Fang; Wang, Chan-Juan; Shi, Huidong; Shou, Weinian; Deng, Ke-Yu; Xin, Hong-Bo

2018-04-22

We previously observed that disruption of FK506-binding protein 12.6 (FKBP12.6) gene resulted in cardiac hypertrophy in male mice. Studies showed that overexpression of FKBP12.6 attenuated thoracic aortic constriction (TAC)-induced cardiac hypertrophy in mice, whereas the adenovirus-mediated overexpression of FKBP12.6 induced hypertrophy and apoptosis in cultured neonatal cardiomyocytes, indicating that the role of FKBP12.6 in cardiac hypertrophy is still controversial. In this study, we aimed to investigate the roles and mechanisms of FKBP12.6 in angiotensin II (AngII)-induced cardiac hypertrophy using various transgenic mouse models in vivo and in vitro. FKBP12.6 knockout (FKBP12.6 -/- ) mice and cardiac-specific FKBP12.6 overexpressing (FKBP12.6 TG) mice were infused with AngII (1500 ng/kg/min) for 14 days subcutaneously by implantation of an osmotic mini-pump. The results showed that FKBP12.6 deficiency aggravated AngII-induced cardiac hypertrophy, while cardiac-specific overexpression of FKBP12.6 prevented hearts from the hypertrophic response to AngII stimulation in mice. Consistent with the results in vivo, overexpression of FKBP12.6 in H9c2 cells significantly repressed the AngII-induced cardiomyocyte hypertrophy, seen as reductions in the cell sizes and the expressions of hypertrophic genes. Furthermore, we demonstrated that the protection of FKBP12.6 on AngII-induced cardiac hypertrophy was involved in reducing the concentration of intracellular Ca 2+ ([Ca 2+ ]i), in which the protein significantly inhibited the key Ca 2+ /calmodulin-dependent signalling pathways such as calcineurin/cardiac form of nuclear factor of activated T cells 4 (NFATc4), calmodulin kinaseII (CaMKII)/MEF-2, AKT/Glycogen synthase kinase 3β (GSK3β)/NFATc4 and AKT/mTOR signalling pathways. Our study demonstrated that FKBP12.6 protects heart from AngII-induced cardiac hypertrophy through inhibiting Ca 2+ /calmodulin-mediated signalling pathways. © 2018 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

Antihelminthic benzimidazoles are novel HIF activators that prevent oxidative neuronal death via binding to tubulin.

PubMed

Aleyasin, Hossein; Karuppagounder, Saravanan S; Kumar, Amit; Sleiman, Sama; Basso, Manuela; Ma, Thong; Siddiq, Ambreena; Chinta, Shankar J; Brochier, Camille; Langley, Brett; Haskew-Layton, Renee; Bane, Susan L; Riggins, Gregory J; Gazaryan, Irina; Starkov, Anatoly A; Andersen, Julie K; Ratan, Rajiv R

2015-01-10

Pharmacological activation of the adaptive response to hypoxia is a therapeutic strategy of growing interest for neurological conditions, including stroke, Huntington's disease, and Parkinson's disease. We screened a drug library with known safety in humans using a hippocampal neuroblast line expressing a reporter of hypoxia-inducible factor (HIF)-dependent transcription. Our screen identified more than 40 compounds with the ability to induce hypoxia response element-driven luciferase activity as well or better than deferoxamine, a canonical activator of hypoxic adaptation. Among the chemical entities identified, the antihelminthic benzimidazoles represented one pharmacophore that appeared multiple times in our screen. Secondary assays confirmed that antihelminthics stabilized the transcriptional activator HIF-1α and induced expression of a known HIF target gene, p21(cip1/waf1), in post-mitotic cortical neurons. The on-target effect of these agents in stimulating hypoxic signaling was binding to free tubulin. Moreover, antihelminthic benzimidazoles also abrogated oxidative stress-induced death in vitro, and this on-target effect also involves binding to free tubulin. These studies demonstrate that tubulin-binding drugs can activate a component of the hypoxic adaptive response, specifically the stabilization of HIF-1α and its downstream targets. Tubulin-binding drugs, including antihelminthic benzimidazoles, also abrogate oxidative neuronal death in primary neurons. Given their safety in humans and known ability to penetrate into the central nervous system, antihelminthic benzimidazoles may be considered viable candidates for treating diseases associated with oxidative neuronal death, including stroke.

Cardiomyocyte architectural plasticity in fetal, neonatal, and adult pig hearts delineated with diffusion tensor MRI.

PubMed

Zhang, Lei; Allen, John; Hu, Lingzhi; Caruthers, Shelton D; Wickline, Samuel A; Chen, Junjie

2013-01-15

Cardiomyocyte organization is a critical determinant of coordinated cardiac contractile function. Because of the acute opening of the pulmonary circulation, the relative workload of the left ventricle (LV) and right ventricle (RV) changes substantially immediately after birth. We hypothesized that three-dimensional cardiomyocyte architecture might be required to adapt rapidly to accommodate programmed perinatal changes of cardiac function. Isolated fixed hearts from pig fetuses or pigs at midgestation, preborn, postnatal day 1 (P1), postnatal day 5, postnatal day 14 (P14), and adulthood (n = 5 for each group) were acquired for diffusion-weighted magnetic resonance imaging. Cardiomyocyte architecture was visualized by three-dimensional fiber tracking and was quantitatively evaluated by the measured helix angle (α(h)). Upon the completion of MRI, hearts were sectioned and stained with hematoxylin/eosin (H&E) to evaluate cardiomyocyte alignment, with picrosirius red to evaluate collagen content, and with anti-Ki67 to evaluate postnatal cell proliferation. The helical architecture of cardiomyocyte was observed as early as the midgestational period. Postnatal changes of cardiomyocyte architecture were observed from P1 to P14, which primary occurred in the septum and RV free wall (RVFW). In the septum, the volume ratio of LV- vs. RV-associated cardiomyocytes rapidly changed from RV-LV balanced pattern at birth to LV dominant pattern by P14. In the RVFW, subendocardial α(h) decreased by ~30° from P1 to P14. These findings indicate that the helical architecture of cardiomyocyte is developed as early as the midgestation period. Substantial and rapid adaptive changes in cardiac microarchitecture suggested considerable developmental plasticity of cardiomyocyte form and function in the postnatal period in response to altered cardiac mechanical function.

Correlation-based discrimination between cardiac tissue and blood for segmentation of 3D echocardiographic images

NASA Astrophysics Data System (ADS)

Saris, Anne E. C. M.; Nillesen, Maartje M.; Lopata, Richard G. P.; de Korte, Chris L.

2013-03-01

Automated segmentation of 3D echocardiographic images in patients with congenital heart disease is challenging, because the boundary between blood and cardiac tissue is poorly defined in some regions. Cardiologists mentally incorporate movement of the heart, using temporal coherence of structures to resolve ambiguities. Therefore, we investigated the merit of temporal cross-correlation for automated segmentation over the entire cardiac cycle. Optimal settings for maximum cross-correlation (MCC) calculation, based on a 3D cross-correlation based displacement estimation algorithm, were determined to obtain the best contrast between blood and myocardial tissue over the entire cardiac cycle. Resulting envelope-based as well as RF-based MCC values were used as additional external force in a deformable model approach, to segment the left-ventricular cavity in entire systolic phase. MCC values were tested against, and combined with, adaptive filtered, demodulated RF-data. Segmentation results were compared with manually segmented volumes using a 3D Dice Similarity Index (3DSI). Results in 3D pediatric echocardiographic images sequences (n = 4) demonstrate that incorporation of temporal information improves segmentation. The use of MCC values, either alone or in combination with adaptive filtered, demodulated RF-data, resulted in an increase of the 3DSI in 75% of the cases (average 3DSI increase: 0.71 to 0.82). Results might be further improved by optimizing MCC-contrast locally, in regions with low blood-tissue contrast. Reducing underestimation of the endocardial volume due to MCC processing scheme (choice of window size) and consequential border-misalignment, could also lead to more accurate segmentations. Furthermore, increasing the frame rate will also increase MCC-contrast and thus improve segmentation.

Cardiomyocyte architectural plasticity in fetal, neonatal, and adult pig hearts delineated with diffusion tensor MRI

PubMed Central

Zhang, Lei; Allen, John; Hu, Lingzhi; Caruthers, Shelton D.; Wickline, Samuel A.

2013-01-01

Cardiomyocyte organization is a critical determinant of coordinated cardiac contractile function. Because of the acute opening of the pulmonary circulation, the relative workload of the left ventricle (LV) and right ventricle (RV) changes substantially immediately after birth. We hypothesized that three-dimensional cardiomyocyte architecture might be required to adapt rapidly to accommodate programmed perinatal changes of cardiac function. Isolated fixed hearts from pig fetuses or pigs at midgestation, preborn, postnatal day 1 (P1), postnatal day 5, postnatal day 14 (P14), and adulthood (n = 5 for each group) were acquired for diffusion-weighted magnetic resonance imaging. Cardiomyocyte architecture was visualized by three-dimensional fiber tracking and was quantitatively evaluated by the measured helix angle (αh). Upon the completion of MRI, hearts were sectioned and stained with hematoxylin/eosin (H&E) to evaluate cardiomyocyte alignment, with picrosirius red to evaluate collagen content, and with anti-Ki67 to evaluate postnatal cell proliferation. The helical architecture of cardiomyocyte was observed as early as the midgestational period. Postnatal changes of cardiomyocyte architecture were observed from P1 to P14, which primary occurred in the septum and RV free wall (RVFW). In the septum, the volume ratio of LV- vs. RV-associated cardiomyocytes rapidly changed from RV-LV balanced pattern at birth to LV dominant pattern by P14. In the RVFW, subendocardial αh decreased by ∼30° from P1 to P14. These findings indicate that the helical architecture of cardiomyocyte is developed as early as the midgestation period. Substantial and rapid adaptive changes in cardiac microarchitecture suggested considerable developmental plasticity of cardiomyocyte form and function in the postnatal period in response to altered cardiac mechanical function. PMID:23161881

Potential benefit of the CT adaptive statistical iterative reconstruction method for pediatric cardiac diagnosis

NASA Astrophysics Data System (ADS)

Miéville, Frédéric A.; Ayestaran, Paul; Argaud, Christophe; Rizzo, Elena; Ou, Phalla; Brunelle, Francis; Gudinchet, François; Bochud, François; Verdun, Francis R.

2010-04-01

Adaptive Statistical Iterative Reconstruction (ASIR) is a new imaging reconstruction technique recently introduced by General Electric (GE). This technique, when combined with a conventional filtered back-projection (FBP) approach, is able to improve the image noise reduction. To quantify the benefits provided on the image quality and the dose reduction by the ASIR method with respect to the pure FBP one, the standard deviation (SD), the modulation transfer function (MTF), the noise power spectrum (NPS), the image uniformity and the noise homogeneity were examined. Measurements were performed on a control quality phantom when varying the CT dose index (CTDIvol) and the reconstruction kernels. A 64-MDCT was employed and raw data were reconstructed with different percentages of ASIR on a CT console dedicated for ASIR reconstruction. Three radiologists also assessed a cardiac pediatric exam reconstructed with different ASIR percentages using the visual grading analysis (VGA) method. For the standard, soft and bone reconstruction kernels, the SD is reduced when the ASIR percentage increases up to 100% with a higher benefit for low CTDIvol. MTF medium frequencies were slightly enhanced and modifications of the NPS shape curve were observed. However for the pediatric cardiac CT exam, VGA scores indicate an upper limit of the ASIR benefit. 40% of ASIR was observed as the best trade-off between noise reduction and clinical realism of organ images. Using phantom results, 40% of ASIR corresponded to an estimated dose reduction of 30% under pediatric cardiac protocol conditions. In spite of this discrepancy between phantom and clinical results, the ASIR method is as an important option when considering the reduction of radiation dose, especially for pediatric patients.

Histone Deacetylase 3 (HDAC3)-dependent Reversible Lysine Acetylation of Cardiac Myosin Heavy Chain Isoforms Modulates Their Enzymatic and Motor Activity*

PubMed Central

Samant, Sadhana A.; Pillai, Vinodkumar B.; Sundaresan, Nagalingam R.; Shroff, Sanjeev G.; Gupta, Mahesh P.

2015-01-01

Reversible lysine acetylation is a widespread post-translational modification controlling the activity of proteins in different subcellular compartments. We previously demonstrated that a class II histone deacetylase (HDAC), HDAC4, and a histone acetyltransferase, p300/CREB-binding protein-associated factor, associate with cardiac sarcomeres and that a class I and II HDAC inhibitor, trichostatin A, enhances contractile activity of myofilaments. In this study we show that a class I HDAC, HDAC3, is also present at cardiac sarcomeres. By immunohistochemical and electron microscopic analyses, we found that HDAC3 was localized to A-band of sarcomeres and capable of deacetylating myosin heavy chain (MHC) isoforms. The motor domains of both cardiac α- and β-MHC isoforms were found to be reversibly acetylated. Biomechanical studies revealed that lysine acetylation significantly decreased the Km for the actin-activated ATPase activity of MHC isoforms. By in vitro motility assay, we found that lysine acetylation increased the actin-sliding velocity of α-myosin by 20% and β-myosin by 36% compared with their respective non-acetylated isoforms. Moreover, myosin acetylation was found to be sensitive to cardiac stress. During induction of hypertrophy, myosin isoform acetylation increased progressively with duration of stress stimuli independently of isoform shift, suggesting that lysine acetylation of myosin could be an early response of myofilaments to increase contractile performance of the heart. These studies provide the first evidence for localization of HDAC3 at myofilaments and uncover a novel mechanism modulating the motor activity of cardiac MHC isoforms. PMID:25911107

Performance of the 2-hour Accelerated Diagnostic Protocol Within the American College of Radiology Imaging Network PA 4005 Cohort

PubMed Central

Mahler, Simon A.; Miller, Chadwick D.; Litt, Harold I.; Gatsonis, Constantine A.; Snyder, Bradley S.; Hollander, Judd E.

2015-01-01

Objectives The 2-hour accelerated diagnostic protocol (ADAPT) is a decision rule designed to identify emergency department (ED) patients with chest pain for early discharge. Previous studies in the Asia-Pacific region demonstrated high sensitivity (97.9% to 99.7%) for major adverse cardiac events (MACE) at 30 days. The objective of this study was to determine the validity of ADAPT for risk stratification in a cohort of U.S. ED patients with suspected acute coronary syndrome (ACS). Methods A secondary analysis of participants enrolled in the American College of Radiology Imaging Network (ACRIN) PA 4005 trial was conducted. This trial enrolled 1,369 patients at least 30 years old with symptoms suggestive of ACS. All data elements were collected prospectively at the time of enrollment. Each patient was classified as low risk or at risk by ADAPT. Early discharge rate and sensitivity for MACE, defined as cardiac death, myocardial infarction (MI), or coronary revascularization at 30 days, were calculated. Results Of 1,140 patients with complete biomarker data, MACE occurred in 31 patients (2.7%). Among 551 of the 1,140 (48.3%, 95% confidence interval [CI] = 45.4% to 51.3%), ADAPT identified for early discharge; five of the 551 (0.9%, 95% CI = 0.3% to 2.1%) had MACE at 30 days. ADAPT was 83.9% (95% CI = 66.3% to 94.5%) sensitive, identifying 26 of 31 patients with MACE. Of the five patients identified for early discharge by ADAPT with MACE, there were no deaths, one patient with MI, and five with revascularizations. Conclusions In this first North American application of the ADAPT strategy, sensitivity for MACE within 30 days was 83.9%. One missed adverse event was a MI, with the remainder representing coronary revascularizations. The effect of missing revascularization events needs further investigation. PMID:25810343

Staying young at heart: autophagy and adaptation to cardiac aging.

PubMed

Leon, Leonardo J; Gustafsson, Åsa B

2016-06-01

Aging is a predominant risk factor for developing cardiovascular disease. Therefore, the cellular processes that contribute to aging are attractive targets for therapeutic interventions that can delay or prevent the development of age-related diseases. Our understanding of the underlying mechanisms that contribute to the decline in cell and tissue functions with age has greatly advanced over the past decade. Classical hallmarks of aging cells include increased levels of reactive oxygen species, DNA damage, accumulation of dysfunctional organelles, oxidized proteins and lipids. These all contribute to a progressive decline in the normal physiological function of the cell and to the onset of age-related conditions. A major cause of the aging process is progressive loss of cellular quality control. Autophagy is an important quality control pathway and is necessary to maintain cardiac homeostasis and to adapt to stress. A reduction in autophagy has been observed in a number of aging models and there is compelling evidence that enhanced autophagy delays aging and extends life span. Enhancing autophagy counteracts age-associated accumulation of protein aggregates and damaged organelles in cells. In this review, we discuss the functional role of autophagy in maintaining homeostasis in the heart, and how a decline is associated with accelerated cardiac aging. We also evaluate therapeutic approaches being researched in an effort to maintain a healthy young heart. Copyright © 2015 Elsevier Ltd. All rights reserved.

Code Blue on Orbit: Treating Cardiac Arrest on the ISS

NASA Technical Reports Server (NTRS)

Bacal, Kira; Redmond, Melissa

2004-01-01

As a result of the Columbia tragedy on February 1,2003, the International Space Station (ISS) crew size has been temporarily reduced from three to two. This change forces adaptations in many operational procedures used by the crew, including medical protocols which were designed for scenarios involving one casualty and two caregivers. The Office of Space Medicine directed that the procedure for the resuscitation of a crewmember in cardiac arrest be rewritten for use by a single care provider. Methods: Adaptation of this procedure made use of current American Heart Association Advanced Cardiac Life Support (ACLS) procedures and reflects necessary compromises between the realities of the operational environment and prompt provision of medical care. Results: Numerous changes were incorporated due to the diminution in available personnel, including substitution of endotracheal rather than intravenous delivery of drugs, more rapid defibrillation, addition of a precordial thump, removal of transcutaneous pacing, streamlining of procedural steps, and clarification of termination criteria. Discussion: The on-orbit care available to the ISS crewmembers is constrained by numerous factors, including crew medical training, minimal medical assets, limited air/ground communication , and a single caregiver for the foreseeable future. All of these combine to make a successful resuscitation unlikely, however, this procedure must ultimately deal with not only the patient's welfare, but also that of the caregiver, the mission, and the program.

[Characteristics of anesthesia in patients with MELAS syndrome: Case report of anesthesia in video-assisted thoracoscopy].

PubMed

Haas, A; Wappler, F

2015-10-01

The mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) syndrome is a disease triggered by a disorder in energy production within mitochondria. The cause of this syndrome is a mutation in the mitochondrial DNA where in 80% of cases an A-to-G mutation is present at nucleotide 3243 and with a prevalence of 18.4/100,000 in the population. Predominantly affected are organ systems with a high energy metabolism, such as the heart, brain and musculature. During the premedication visit a thorough patient history and examination with respect to neurological impairments must be carried out. Epilepsy and the appropriate permanent medication lead to possible alterations in effectiveness of anesthetics and muscle relaxants which are difficult to predict. An extensive patient cardiac history and a preoperative electrocardiogram (ECG) for an appraisal of possible disorders in the cardiac conduction system and when necessary extended cardiac diagnostics, are recommended. The monitoring must be adapted depending on the functional limitations and the forthcoming intervention and when necessary a postoperative surveillance in an intensive care unit should be initiated. Knowledge of the special features of MELAS syndrome in association with a consideration of the characteristics of anesthesia in MELAS patients and an individually adapted intensified perioperative surveillance, can contribute to a reduction in perioperative morbidity in patients suffering from MELAS syndrome.

Emergent Fields through Adaptation and Identity: Overcoming Social Distance

ERIC Educational Resources Information Center

DeGennaro, Donna; Brown, Tiffany

2009-01-01

We examine the inseparability of one's environment with the elements of adaptation and identity. Specifically, we revisit the Project H.O.M.E. learning environment as we suggest that the entities of adaption and environment are not only binding, but also naturally in constant flux as they interact with each other. Contrary to nature, however, the…

Enantiomeric and Diastereomeric Self-Assembled Multivalent (SAMul) Nanostructures - Understanding the Effects of Chirality on Binding to Polyanionic Heparin and DNA.

PubMed

Thornalley, Kiri; Laurini, Erik; Pricl, Sabrina; Smith, David K

2018-05-15

A family of four self-assembling lipopeptides containing Ala-Lys peptides attached to a C16 aliphatic chain was synthesised. These compounds form two enantiomeric pairs that bear a diastereomeric relationship to one another (C16-L-Ala-L-Lys/C16-D-Ala-D-Lys) and (C16-D-Ala-L-Lys/C16-L-Ala-D-Lys). These diastereomeric pairs have very different critical micelle concentrations (CMCs), with LL/DD < DL/LD suggesting more effective assembly of the former. The self-assembled multivalent (SAMul) systems bind biological polyanions as result of the cationic lysine groups on their surfaces. Polyanion binding was investigated using dye displacement assays and isothermal calorimetry (ITC). On heparin binding, there was no significant enantioselectivity, but there was a binding preference for the diastereomeric assemblies with lower CMCs. Conversely, on binding DNA, there was a significant enantioselective preference for systems displaying D-lysine ligands, with a further slight preference for attachment to L-alanine, with the CMC being irrelevant. Binding to adaptive, ill-defined heparin has a large favourable entropic term, suggesting it depends primarily on the cationic SAMul nanostructure maximising surface contact with heparin, which can adapt, displacing solvent and other ions. Conversely, binding to well-defined, shape-persistent DNA has a larger favourable enthalpic term, and combined with the enantioselectivity, this allows us to suggest that its SAMul binding is based on optimised individual electrostatic interactions at the molecular level, with a preference for binding to D-lysine. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Later Competence and Adaptation in Infants Who Survive Severe Heart Defects.

ERIC Educational Resources Information Center

O'Dougherty, Margaret; And Others

1983-01-01

Describes a model of risk potential for developmental outcome that was based on cardiac, medical, surgical, and family stress factors in 31 children with transposition of the great arteries. All children had undergone reparative open heart surgery utilizing cardiopulmonary bypass during infancy. (Author/RH)

Does Resistance Training Stimulate Cardiac Muscle Hypertrophy?

ERIC Educational Resources Information Center

Bloomer, Richard J.

2003-01-01

Reviews the literature on the left ventricular structural adaptations induced by resistance/strength exercise, focusing on human work, particularly well-trained strength athletes engaged in regular, moderate- to high-intensity resistance training (RT). The article discusses both genders and examines the use of anabolic-androgenic steroids in…

Lifestyle Improvement Program for Seniors.

ERIC Educational Resources Information Center

Barclay, Ralph

The Wayne State College Lifestyle Improvement Program for Seniors, based on the wellness concept, is designed to facilitate social interaction and health through physical activities. It is adaptable to a variety of individual needs and preferences, including exercises for cardiac rehabilitation patients. Any person over 50 can participate at no…

Mechanisms of physiological and pathological cardiac hypertrophy.

PubMed

Nakamura, Michinari; Sadoshima, Junichi

2018-04-19

Cardiomyocytes exit the cell cycle and become terminally differentiated soon after birth. Therefore, in the adult heart, instead of an increase in cardiomyocyte number, individual cardiomyocytes increase in size, and the heart develops hypertrophy to reduce ventricular wall stress and maintain function and efficiency in response to an increased workload. There are two types of hypertrophy: physiological and pathological. Hypertrophy initially develops as an adaptive response to physiological and pathological stimuli, but pathological hypertrophy generally progresses to heart failure. Each form of hypertrophy is regulated by distinct cellular signalling pathways. In the past decade, a growing number of studies have suggested that previously unrecognized mechanisms, including cellular metabolism, proliferation, non-coding RNAs, immune responses, translational regulation, and epigenetic modifications, positively or negatively regulate cardiac hypertrophy. In this Review, we summarize the underlying molecular mechanisms of physiological and pathological hypertrophy, with a particular emphasis on the role of metabolic remodelling in both forms of cardiac hypertrophy, and we discuss how the current knowledge on cardiac hypertrophy can be applied to develop novel therapeutic strategies to prevent or reverse pathological hypertrophy.

Mechanisms of right heart disease in pulmonary hypertension (2017 Grover Conference Series).

PubMed

Asosingh, Kewal; Erzurum, Serpil

2018-01-01

Current dogma is that pathological hypertrophy of the right ventricle is a direct consequence of pulmonary vascular remodeling. However, progression of right ventricle dysfunction is not always lung-dependent. Increased afterload caused by pulmonary vascular remodeling initiates the right ventricle hypertrophy, but determinants leading to adaptive or maladaptive hypertrophy and failure remain unknown. Ischemia in a hypertrophic right ventricle may directly contribute to right heart failure. Rapidly enlarging cardiomyocytes switch from aerobic to anaerobic energy generation resulting in cell growth under relatively hypoxic conditions. Cardiac muscle reacts to an increased afterload by over-activation of the sympathetic system and uncoupling and downregulation of β-adrenergic receptors. Recent studies suggest that β blocker therapy in PH is safe, well tolerated, and preserves right ventricle function and cardiac output by reducing right ventricular glycolysis. Fibrosis, an evolutionary conserved process in host defense and wound healing, is dysregulated in maladaptive cardiac tissue contributing directly to right ventricle failure. Despite several mechanisms having been suggested in right heart disease, the causes of maladaptive cardiac remodeling remain unknown and require further research.

Maternal hyperthyroidism increases the susceptibility of rat adult offspring to cardiovascular disorders.

PubMed

Lino, Caroline A; da Silva, Ivson Bezerra; Shibata, Caroline E R; Monteiro, Priscilla de S; Barreto-Chaves, Maria Luiza M

2015-11-15

Suboptimal intrauterine conditions as changed hormone levels during critical periods of the development are considered an insult and implicate in physiological adaptations which may result in pathological outcomes in later life. This study evaluated the effect of maternal hyperthyroidism (hyper) on cardiac function in adult offspring and the possible involvement of cardiac Renin-Angiotensin System (RAS) in this process. Wistar dams received orally thyroxin (12 mg/L) from gestational day 9 (GD9) until GD18. Adult offspring at postnatal day 90 (PND90) from hyper dams presented increased SBP evaluated by plethysmography and worse recovery after ischemia-reperfusion (I/R), as evidenced by decreased LVDP, +dP/dT and -dP/dT at 25 min of reperfusion and by increased infarct size. Increased cardiac Angiotensin I/II levels and AT1R in hyper offspring were verified. Herein, we provide evidences that maternal hyperthyroidism leads to altered expression of RAS components in adult offspring, which may be correlated with worse recovery of the cardiac performance after ischemic insults and hypertension. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

OC19 - Measuring feasibility, reliability and validity of the Greek version of PedsQL cardiac module.

PubMed

Drakouli, Maria; Petsios, Konstantinos; Matziou, Vasiliki

2016-05-09

Theme: Cardiology Introduction: Measuring quality of life (QoL) in children and adolescents with congenital heart disease (CHD) is of great clinical importance. The aim of the study was: (a) to adapt the PedsQL Cardiac Module for children aged two to 18 years with CHD in a sample of the Greek population; (b) to determine its reliability and validity. Forward and backward translation methodology was used. Parents and children completed the instrument during: (a) hospitalization and (b) visits in the paediatric cardiology outpatient department. Cross-informant variance between children and parents was thoroughly assessed. Missing item responses did not exceed 5%. All internal consistency reliability coefficients for the inventory exceeded the minimum standards for group comparisons, over 0.75. Hypothesized correlations between cardiac module and core scales were statistically significant, (p<0.05). Agreement between children and parents was relatively high. Pilot study results will be additionally presented. The findings support the feasibility, reliability and validity of the Greek translation of the PedsQL Cardiac Module in children with congenital heart defect (CHD).

Evaluation of cerebral-cardiac syndrome using echocardiography in a canine model of acute traumatic brain injury.

PubMed

Qian, Rong; Yang, Weizhong; Wang, Xiumei; Xu, Zhen; Liu, Xiaodong; Sun, Bing

2015-01-01

Previous studies have confirmed that traumatic brain injury (TBI) can induce general adaptation syndrome (GAS), which subsequently results in myocardial dysfunction and damage in some patients with acute TBI; this condition is also termed as cerebral-cardiac syndrome. However, most clinicians ignore the detection and treatment of myocardial dysfunction, and instead concentrate only on the serious neural damage that is observed in acute TBI, which is one of the most important fatal factors. Therefore, clarification is urgently needed regarding the relationship between TBI and myocardial dysfunction. In the present study, we evaluated 18 canine models of acute TBI, by using real-time myocardial contrast echocardiography and strain rate imaging to accurately evaluate myocardial function and regional microcirculation, including the strain rate of the different myocardial segments, time-amplitude curves, mean ascending slope of the curve, and local myocardial blood flow. Our results suggest that acute TBI often results in cerebral-cardiac syndrome, which rapidly progresses to the serious stage within 3 days. This study is the first to provide comprehensive ultrasonic characteristics of cerebral-cardiac syndrome in an animal model of TBI.

Cardiac Fibroblast-Specific Activating Transcription Factor 3 Protects Against Heart Failure by Suppressing MAP2K3-p38 Signaling.

PubMed

Li, Yulin; Li, Zhenya; Zhang, Congcong; Li, Ping; Wu, Yina; Wang, Chunxiao; Bond Lau, Wayne; Ma, Xin-Liang; Du, Jie

2017-05-23

Hypertensive ventricular remodeling is a common cause of heart failure. However, the molecular mechanisms regulating ventricular remodeling remain poorly understood. We used a discovery-driven/nonbiased approach to identify increased activating transcription factor 3 (ATF3) expression in hypertensive heart. We used loss/gain of function approaches to understand the role of ATF3 in heart failure. We also examined the mechanisms through transcriptome, chromatin immunoprecipitation sequencing analysis, and in vivo and in vitro experiments. ATF3 expression increased in murine hypertensive heart and human hypertrophic heart. Cardiac fibroblast cells are the primary cell type expressing high ATF3 levels in response to hypertensive stimuli. ATF3 knockout (ATF3KO) markedly exaggerated hypertensive ventricular remodeling, a state rescued by lentivirus-mediated/miRNA-aided cardiac fibroblast-selective ATF3 overexpression. Conversely, conditional cardiac fibroblast cell-specific ATF3 transgenic overexpression significantly ameliorated ventricular remodeling and heart failure. We identified Map2K3 as a novel ATF3 target. ATF3 binds with the Map2K3 promoter, recruiting HDAC1, resulting in Map2K3 gene-associated histone deacetylation, thereby inhibiting Map2K3 expression. Genetic Map2K3 knockdown rescued the profibrotic/hypertrophic phenotype in ATF3KO cells. Last, we demonstrated that p38 is the downstream molecule of Map2K3 mediating the profibrotic/hypertrophic effects in ATF3KO animals. Inhibition of p38 signaling reduced transforming growth factor-β signaling-related profibrotic and hypertrophic gene expression, and blocked exaggerated cardiac remodeling in ATF3KO cells. Our study provides the first evidence that ATF3 upregulation in cardiac fibroblasts in response to hypertensive stimuli protects the heart by suppressing Map2K3 expression and subsequent p38-transforming growth factor-β signaling. These results suggest that positive modulation of cardiac fibroblast ATF3 may represent a novel therapeutic approach against hypertensive cardiac remodeling. © 2017 American Heart Association, Inc.

H- ras deletion protects against angiotensin II-induced arterial hypertension and cardiac remodeling through protein kinase G-Iβ pathway activation.

PubMed

Martín-Sánchez, Paloma; Luengo, Alicia; Griera, Mercedes; Orea, María Jesús; López-Olañeta, Marina; Chiloeches, Antonio; Lara-Pezzi, Enrique; de Frutos, Sergio; Rodríguez-Puyol, Manuel; Calleros, Laura; Rodríguez-Puyol, Diego

2018-02-01

Ras proteins regulate cell survival, growth, differentiation, blood pressure, and fibrosis in some organs. We have demonstrated that H- ras gene deletion produces mice hypotension via a soluble guanylate cyclase-protein kinase G (PKG)-dependent mechanism. In this study, we analyzed the consequences of H- ras deletion on cardiac remodeling induced by continuous angiotensin II (AngII) infusion and the molecular mechanisms implied. Left ventricular posterior wall thickness and mass and cardiomyocyte cross-sectional area were similar between AngII-treated H-Ras knockout (H -ras -/- ) and control wild-type (H -ras +/+ ) mice, as were extracellular matrix protein expression. Increased cardiac PKG-Iβ protein expression in H -ras -/- mice suggests the involvement of this protein in heart protection. Ex vivo experiments on cardiac explants could support this mechanism, as PKG blockade blunted protection against AngII-induced cardiac hypertrophy and fibrosis markers in H -ras -/- mice. Genetic modulation studies in cardiomyocytes and cardiac and embryonic fibroblasts revealed that the lack of H-Ras down-regulates the B-RAF/MEK/ERK pathway, which induces the glycogen synthase kinase-3β-dependent activation of the transcription factor, cAMP response element-binding protein, which is responsible for PKG-Iβ overexpression in H -ras -/- mouse embryonic fibroblasts. This study demonstrates that H- ras deletion protects against AngII-induced cardiac remodeling, possibly via a mechanism in which PKG-Iβ overexpression could play a partial role, and points to H-Ras and/or downstream proteins as potential therapeutic targets in cardiovascular disease.-Martín-Sánchez, P., Luengo, A., Griera, M., Orea, M. J., López-Olañeta, M., Chiloeches, A., Lara-Pezzi, E., de Frutos, S., Rodríguez-Puyol, M., Calleros, L., Rodríguez-Puyol, D. H- ras deletion protects against angiotensin II-induced arterial hypertension and cardiac remodeling through protein kinase G-Iβ pathway activation.

Application of Adaptive Starling-Like Controller to Total Artificial Heart Using Dual Rotary Blood Pumps.

PubMed

Ng, Boon C; Smith, Peter A; Nestler, Frank; Timms, Daniel; Cohn, William E; Lim, Einly

2017-03-01

The successful clinical applicability of rotary left ventricular assist devices (LVADs) has led to research interest in devising a total artificial heart (TAH) using two rotary blood pumps (RBPs). The major challenge when using two separately controlled LVADs for TAH support is the difficulty in maintaining the balance between pulmonary and systemic blood flows. In this study, a starling-like controller (SLC) hybridized with an adaptive mechanism was developed for a dual rotary LVAD TAH. The incorporation of the adaptive mechanism was intended not only to minimize the risk of pulmonary congestion and atrial suction but also to match cardiac demand. A comparative assessment was performed between the proposed adaptive starling-like controller (A-SLC) and a conventional SLC as well as a constant speed controller. The performance of all controllers was evaluated by subjecting them to three simulated scenarios [rest, exercise, head up tilt (HUT)] using a mock circulation loop. The overall results showed that A-SLC was superior in matching pump flow to cardiac demand without causing hemodynamic instabilities. In contrast, improper flow regulation by the SLC resulted in pulmonary congestion during exercise. From resting supine to HUT, overpumping of the RBPs at fixed speed (FS) caused atrial suction, whereas implementation of SLC resulted in insufficient flow. The comparative study signified the potential of the proposed A-SLC for future TAH implementation particularly among outpatients, who are susceptible to variety of clinical scenarios.

On lifting the fog of war in the battle on heart disease: Star Wars technology in pursuit of a seamless integration strategy.

PubMed

Espinosa, J A; Kosnik, L K; Kraitsik, M; Dillow, J C

1997-01-01

In our efforts to reduce cardiac morbidity and mortality we often use terms such as the "battle" or "war" on heart disease. If we believe efforts to reduce cardiac disease are the moral equivalent of war, then perhaps we should explore ways that military strategic and tactical metaphors can be applied through technology to the cardiac battle. In this article we explore three major areas for technological advancement: adaptation of the strategies of outcomes management and evidence-based medicine, computer simulation and animation efforts to create horizontal and vertical integration of strategic efforts, and use of interactive multimedia in "recruiting an army" through community empowerment. The overall goal is to find ways to lift "the fog of war" in the battle on heart disease, in order to further the integration of our various efforts.

Cysteine-containing peptide tag for site-specific conjugation of proteins

DOEpatents

Backer, Marina V.; Backer, Joseph M.

2008-04-08

The present invention is directed to a biological conjugate, comprising: (a) a targeting moiety comprising a polypeptide having an amino acid sequence comprising the polypeptide sequence of SEQ ID NO:2 and the polypeptide sequence of a selected targeting protein; and (b) a binding moiety bound to the targeting moiety; the biological conjugate having a covalent bond between the thiol group of SEQ ID NO:2 and a functional group in the binding moiety. The present invention is directed to a biological conjugate, comprising: (a) a targeting moiety comprising a polypeptide having an amino acid sequence comprising the polypeptide sequence of SEQ ID NO:2 and the polypeptide sequence of a selected targeting protein; and (b) a binding moiety that comprises an adapter protein, the adapter protein having a thiol group; the biological conjugate having a disulfide bond between the thiol group of SEQ ID NO:2 and the thiol group of the adapter protein. The present invention is also directed to biological sequences employed in the above biological conjugates, as well as pharmaceutical preparations and methods using the above biological conjugates.

Cysteine-containing peptide tag for site-specific conjugation of proteins

DOEpatents

Backer, Marina V.; Backer, Joseph M.

2010-10-05

The present invention is directed to a biological conjugate, comprising: (a) a targeting moiety comprising a polypeptide having an amino acid sequence comprising the polypeptide sequence of SEQ ID NO:2 and the polypeptide sequence of a selected targeting protein; and (b) a binding moiety bound to the targeting moiety; the biological conjugate having a covalent bond between the thiol group of SEQ ID NO:2 and a functional group in the binding moiety. The present invention is directed to a biological conjugate, comprising: (a) a targeting moiety comprising a polypeptide having an amino acid sequence comprising the polypeptide sequence of SEQ ID NO:2 and the polypeptide sequence of a selected targeting protein; and (b) a binding moiety that comprises an adapter protein, the adapter protein having a thiol group; the biological conjugate having a disulfide bond between the thiol group of SEQ ID NO:2 and the thiol group of the adapter protein. The present invention is also directed to biological sequences employed in the above biological conjugates, as well as pharmaceutical preparations and methods using the above biological conjugates.

A human-infecting H10N8 influenza virus retains a strong preference for avian-type receptors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Heng; de Vries, Robert  P.; Tzarum, Netanel

Recent avian-origin H10N8 influenza A viruses that have infected humans pose a potential pandemic threat. Alterations in the viral surface glycoprotein, hemagglutinin (HA), typically are required for influenza A viruses to cross the species barrier for adaptation to a new host, but whether H10N8 contains adaptations supporting human infection remains incompletely understood. In this paper, we investigated whether H10N8 HA can bind human receptors. Sialoside glycan microarray analysis showed that the H10 HA retains a strong preference for avian receptor analogs and negligible binding to human receptor analogs. Crystal structures of H10 HA with avian and human receptor analogs revealedmore » the basis for preferential recognition of avian-like receptors. Furthermore, introduction of mutations into the H10 receptor-binding site (RBS) known to convert other HA subtypes from avian to human receptor specificity failed to switch preference to human receptors. In conclusion, collectively these findings suggest that the current H10N8 human isolates are poorly adapted for efficient human-to-human transmission.« less

A human-infecting H10N8 influenza virus retains a strong preference for avian-type receptors

DOE PAGES

Zhang, Heng; de Vries, Robert  P.; Tzarum, Netanel; ...

2015-03-11

Recent avian-origin H10N8 influenza A viruses that have infected humans pose a potential pandemic threat. Alterations in the viral surface glycoprotein, hemagglutinin (HA), typically are required for influenza A viruses to cross the species barrier for adaptation to a new host, but whether H10N8 contains adaptations supporting human infection remains incompletely understood. In this paper, we investigated whether H10N8 HA can bind human receptors. Sialoside glycan microarray analysis showed that the H10 HA retains a strong preference for avian receptor analogs and negligible binding to human receptor analogs. Crystal structures of H10 HA with avian and human receptor analogs revealedmore » the basis for preferential recognition of avian-like receptors. Furthermore, introduction of mutations into the H10 receptor-binding site (RBS) known to convert other HA subtypes from avian to human receptor specificity failed to switch preference to human receptors. In conclusion, collectively these findings suggest that the current H10N8 human isolates are poorly adapted for efficient human-to-human transmission.« less

Paradoxical enhancement of chemoreceptor detection sensitivity by a sensory adaptation enzyme

PubMed Central

Han, Xue-Sheng; Dahlquist, Frederick W.; Parkinson, John S.

2017-01-01

A sensory adaptation system that tunes chemoreceptor sensitivity enables motile Escherichia coli cells to track chemical gradients with high sensitivity over a wide dynamic range. Sensory adaptation involves feedback control of covalent receptor modifications by two enzymes: CheR, a methyltransferase, and CheB, a methylesterase. This study describes a CheR function that opposes the signaling consequences of its catalytic activity. In the presence of CheR, a variety of mutant serine chemoreceptors displayed up to 40-fold enhanced detection sensitivity to chemoeffector stimuli. This response enhancement effect did not require the known catalytic activity of CheR, but did involve a binding interaction between CheR and receptor molecules. Response enhancement was maximal at low CheR:receptor stoichiometry and quantitative analyses argued against a reversible binding interaction that simply shifts the ON–OFF equilibrium of receptor signaling complexes. Rather, a short-lived CheR binding interaction appears to promote a long-lasting change in receptor molecules, either a covalent modification or conformation that enhances their response to attractant ligands. PMID:28827352

The Delicate Balance of Preorganisation and Adaptability in Multiply Bonded Host-Guest Complexes.

PubMed

von Krbek, Larissa K S; Achazi, Andreas J; Schoder, Stefan; Gaedke, Marius; Biberger, Tobias; Paulus, Beate; Schalley, Christoph A

2017-02-24

Rigidity and preorganisation are believed to be required for high affinity in multiply bonded supramolecular complexes as they help reduce the entropic penalty of the binding event. This comes at the price that such rigid complexes are sensitive to small geometric mismatches. In marked contrast, nature uses more flexible building blocks. Thus, one might consider putting the rigidity/high-affinity notion to the test. Multivalent crown/ammonium complexes are ideal for this purpose as the monovalent interaction is well understood. A series of divalent complexes with different spacer lengths and rigidities has thus been analysed to correlate chelate cooperativities and spacer properties. Too long spacers reduce chelate cooperativity compared to exactly matching ones. However, in contrast to expectation, flexible guests bind with chelate cooperativities clearly exceeding those of rigid structures. Flexible spacers adapt to small geometric host-guest mismatches. Spacer-spacer interactions help overcome the entropic penalty of conformational fixation during binding and a delicate balance of preorganisation and adaptability is at play in multivalent complexes. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

An accelerated diagnostic protocol for the early, safe discharge of low-risk chest pain patients.

PubMed

Altherwi, Tawfeeq; Grad, Willis B

2015-07-01

Can an accelerated 2-hour diagnostic protocol using the cardiac troponin I (cTnI) measurement as the only biomarker be implemented to allow an earlier and safe discharge of low-risk chest pain patients? Than M, Cullen L, Aldous S, et al. 2-Hour accelerated diagnostic protocol to assess patients with chest pain symptoms using contemporary troponins as the only biomarker: the ADAPT trial. J Am Coll Cardiol 2012;59(23):2091-8. To determine whether an accelerated diagnostic protocol (ADP) for possible cardiac chest pain could identify low-risk patients suitable for early discharge using cTnI as the sole biomarker.

Cardiac Gab1 deletion leads to dilated cardiomyopathy associated with mitochondrial damage and cardiomyocyte apoptosis

PubMed Central

Zhao, J; Yin, M; Deng, H; Jin, F Q; Xu, S; Lu, Y; Mastrangelo, M A; Luo, H; Jin, Z G

2016-01-01

A vital step in the development of heart failure is the transition from compensatory cardiac hypertrophy to decompensated dilated cardiomyopathy (DCM) during cardiac remodeling under mechanical or pathological stress. However, the molecular mechanisms underlying the development of DCM and heart failure remain incompletely understood. In the present study, we investigate whether Gab1, a scaffolding adaptor protein, protects against hemodynamic stress-induced DCM and heat failure. We first observed that the protein levels of Gab1 were markedly reduced in hearts from human patients with DCM and from mice with experimental viral myocarditis in which DCM developed. Next, we generated cardiac-specific Gab1 knockout mice (Gab1-cKO) and found that Gab-cKO mice developed DCM in hemodynamic stress-dependent and age-dependent manners. Under transverse aorta constriction (TAC), Gab1-cKO mice rapidly developed decompensated DCM and heart failure, whereas Gab1 wild-type littermates exhibited adaptive left ventricular hypertrophy without changes in cardiac function. Mechanistically, we showed that Gab1-cKO mouse hearts displayed severe mitochondrial damages and increased cardiomyocyte apoptosis. Loss of cardiac Gab1 in mice impaired Gab1 downstream MAPK signaling pathways in the heart under TAC. Gene profiles further revealed that ablation of Gab1 in heart disrupts the balance of anti- and pro-apoptotic genes in cardiomyocytes. These results demonstrate that cardiomyocyte Gab1 is a critical regulator of the compensatory cardiac response to aging and hemodynamic stress. These findings may provide new mechanistic insights and potential therapeutic target for DCM and heart failure. PMID:26517531