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Sample records for improves contractile function

  1. Depressed contractile function due to canine mitral regurgitation improves after correction of the volume overload.

    PubMed Central

    Nakano, K; Swindle, M M; Spinale, F; Ishihara, K; Kanazawa, S; Smith, A; Biederman, R W; Clamp, L; Hamada, Y; Zile, M R

    1991-01-01

    It is known that long-standing volume overload on the left ventricle due to mitral regurgitation eventually leads to contractile dysfunction. However, it is unknown whether or not correction of the volume overload can lead to recovery of contractility. In this study we tested the hypothesis that depressed contractile function due to volume overload in mitral regurgitation could return toward normal after mitral valve replacement. Using a canine model of mitral regurgitation which is known to produce contractile dysfunction, we examined contractile function longitudinally in seven dogs at baseline, after 3 mo of mitral regurgitation, 1 mo after mitral valve replacement, and 3 mo after mitral valve replacement. After 3 mo of mitral regurgitation (regurgitant fraction 0.62 +/- 0.04), end-diastolic volume had nearly doubled from 68 +/- 6.8 to 123 +/- 12.1 ml (P less than 0.05). All five indices of contractile function which we examined were depressed. For instance, maximum fiber elastance (EmaxF) obtained by assessment of time-varying elastance decreased from 5.95 +/- 0.71 to 2.25 +/- 0.18 (P less than 0.05). The end-systolic stiffness constant (k) was also depressed from 4.2 +/- 0.4 to 2.1 +/- 0.3. 3 mo after mitral valve replacement all indexes of contractile function had returned to or toward normal (e.g., EmaxF 3.65 +/- 0.21 and k 4.2 +/- 0.3). We conclude that previously depressed contractile function due to volume overload can improve after correction of the overload. PMID:1828252

  2. Creatine kinase overexpression improves ATP kinetics and contractile function in postischemic myocardium

    PubMed Central

    Akki, Ashwin; Su, Jason; Yano, Toshiyuki; Gupta, Ashish; Wang, Yibin; Leppo, Michelle K.; Chacko, Vadappuram P.; Steenbergen, Charles

    2012-01-01

    Reduced myofibrillar ATP availability during prolonged myocardial ischemia may limit post-ischemic mechanical function. Because creatine kinase (CK) is the prime energy reserve reaction of the heart and because it has been difficult to augment ATP synthesis during and after ischemia, we used mice that overexpress the myofibrillar isoform of creatine kinase (CKM) in cardiac-specific, conditional fashion to test the hypothesis that CKM overexpression increases ATP delivery in ischemic-reperfused hearts and improves functional recovery. Isolated, retrograde-perfused hearts from control and CKM mice were subjected to 25 min of global, no-flow ischemia and 40 min of reperfusion while cardiac function [rate pressure product (RPP)] was monitored. A combination of 31P-nuclear magnetic resonance experiments at 11.7T and biochemical assays was used to measure the myocardial rate of ATP synthesis via CK (CK flux) and intracellular pH (pHi). Baseline CK flux was severalfold higher in CKM hearts (8.1 ± 1.0 vs. 32.9 ± 3.8, mM/s, control vs. CKM; P < 0.001) with no differences in phosphocreatine concentration [PCr] and RPP. End-ischemic pHi was higher in CKM hearts than in control hearts (6.04 ± 0.12 vs. 6.37 ± 0.04, control vs. CKM; P < 0.05) with no differences in [PCr] and [ATP] between the two groups. Post-ischemic PCr (66.2 ± 1.3 vs. 99.1 ± 8.0, %preischemic levels; P < 0.01), CK flux (3.2 ± 0.4 vs. 14.0 ± 1.2 mM/s; P < 0.001) and functional recovery (13.7 ± 3.4 vs. 64.9 ± 13.2%preischemic RPP; P < 0.01) were significantly higher and lactate dehydrogenase release was lower in CKM than in control hearts. Thus augmenting cardiac CKM expression attenuates ischemic acidosis, reduces injury, and improves not only high-energy phosphate content and the rate of CK ATP synthesis in postischemic myocardium but also recovery of contractile function. PMID:22886411

  3. Disruption of ROCK1 gene attenuates cardiac dilation and improves contractile function in pathological cardiac hypertrophy

    PubMed Central

    Shi, Jianjian; Zhang, Yi-Wei; Summers, Lelia J.; Dorn, Gerald W.; Wei, Lei

    2009-01-01

    Summary The development of left ventricular cardiomyocyte hypertrophy in response to increased hemodynamic load and neurohormonal stress is initially a compensatory response. However, persistent stress eventually leads to dilated heart failure, which is a common cause of heart failure in human hypertensive and valvular heart disease. We have recently reported that Rho-associated coiled-coil containing protein kinase 1 (ROCK1) homozygous knockout mice exhibited reduced cardiac fibrosis and cardiomyocyte apoptosis, while displaying a preserved compensatory hypertrophic response to pressure overload. In this study, we have tested the effects of ROCK1 deficiency on cardiac hypertrophy, dilation, and dysfunction. We have shown that ROCK1 deletion attenuated left ventricular dilation and contractile dysfunction, but not hypertrophy, in a transgenic model of Gαq overexpression-induced hypertrophy which represents a well-characterized and highly relevant genetic mouse model of pathological hypertrophy. Although the development of cardiomyocyte hypertrophy was not affected, ROCK1 deletion in Gαq mice resulted in a concentric hypertrophic phenotype associated with reduced induction of hypertrophic markers indicating that ROCK1 deletion could favorably modify hypertrophy without inhibiting it. Furthermore, ROCK1 deletion also improved contractile response to β-adrenergic stimulation in Gαq transgenic mice. Consistent with this observation, ROCK1 deletion prevented down-regulation of type V/VI adenylyl cyclase expression, which is associated with the impaired β-adrenergic signaling in Gαq mice. The present study establishes for the first time a role for ROCK1 in cardiac dilation and contractile dysfunction. PMID:18178218

  4. Adeno-associated virus vector-mediated minidystrophin gene therapy improves dystrophic muscle contractile function in mdx mice.

    PubMed

    Watchko, Jon; O'Day, Terry; Wang, Bing; Zhou, Liqiao; Tang, Ying; Li, Juan; Xiao, Xiao

    2002-08-10

    Duchenne muscular dystrophy (DMD) is the most common disabling and lethal genetic muscle disorder, afflicting 1 of every 3500 males. Patients with DMD experience progressive muscle degeneration and weakness and succumb to respiratory or cardiac failure by their early twenties. No treatment is currently available for DMD. Mutations in the dystrophin gene result in lack of a functional dystrophin protein in striated muscle, which induces instability in the muscle cell membrane leading to persistent muscle injury after contraction. We have previously created novel minidystrophin genes and demonstrated that adeno-associated virus (AAV)-mediated intramuscular delivery of the minigenes effectively ameliorated mdx dystrophic histopathology and led to normal cell membrane integrity for more than 1 year. In this paper, we investigated whether AAV-minidystrophin could also improve mdx muscle contractile function. Two-month-old adult male mdx mice, with established muscular dystrophy, were given a single-dose injection of an AAV-minidystrophin vector in the tibialis anterior (TA) muscle of one leg, with the untreated contralateral leg used as a control. The treated TA muscle showed both (1) a significant increase in isometric force generation and (2) a significant increase in resistance to lengthening activation-induced muscle force decrements. We conclude that AAV-minidystrophin gene treatment is effective in improving mdx muscle contractile function. PMID:12215266

  5. Neuromuscular Junction Formation in Tissue-Engineered Skeletal Muscle Augments Contractile Function and Improves Cytoskeletal Organization

    PubMed Central

    Martin, Neil R.W.; Passey, Samantha L.; Player, Darren J.; Mudera, Vivek; Baar, Keith; Greensmith, Linda

    2015-01-01

    Neuromuscular and neurodegenerative diseases are conditions that affect both motor neurons and the underlying skeletal muscle tissue. At present, the majority of neuromuscular research utilizes animal models and there is a growing need to develop novel methodologies that can be used to help understand and develop treatments for these diseases. Skeletal muscle tissue-engineered constructs exhibit many of the characteristics of the native tissue such as accurate fascicular structure and generation of active contractions. However, to date, there has been little consideration toward the integration of engineered skeletal muscle with motor neurons with the aim of neuromuscular junction (NMJ) formation, which would provide a model to investigate neuromuscular diseases and basic biology. In the present work we isolated primary embryonic motor neurons and neonatal myoblasts from Sprague-Dawley rats, and cocultured the two cell types in three-dimensional tissue-engineered fibrin hydrogels with the aim of NMJ formation. Immunohistochemistry revealed myotube formation in a fascicular arrangement and neurite outgrowth from motor neuron cell bodies toward the aligned myotubes. Furthermore, colocalization of pre- and postsynaptic proteins and chemical inhibition of spontaneous myotube twitch indicated the presence of NMJs in the innervated constructs. When electrical field stimulation was employed to evoke isometric contractions, maximal twitch and tetanic force were higher in the constructs cocultured with motor neurons, which may, in part, be explained by improved myotube cytoskeletal organization in these constructs. The fabrication of such constructs may be useful tools for investigating neuromuscular pharmaceuticals and improving the understanding of neuromuscular pathologies. PMID:26166548

  6. Contractile Function During Angiotensin-II Activation

    PubMed Central

    Zhang, Min; Prosser, Benjamin L.; Bamboye, Moradeke A.; Gondim, Antonio N.S.; Santos, Celio X.; Martin, Daniel; Ghigo, Alessandra; Perino, Alessia; Brewer, Alison C.; Ward, Christopher W.; Hirsch, Emilio; Lederer, W. Jonathan; Shah, Ajay M.

    2015-01-01

    Background Renin-angiotensin system activation is a feature of many cardiovascular conditions. Activity of myocardial reduced nicotinamide adenine dinucleotide phosphate oxidase 2 (NADPH oxidase 2 or Nox2) is enhanced by angiotensin II (Ang II) and contributes to increased hypertrophy, fibrosis, and adverse remodeling. Recent studies found that Nox2-mediated reactive oxygen species production modulates physiological cardiomyocyte function. Objectives This study sought to investigate the effects of cardiomyocyte Nox2 on contractile function during increased Ang II activation. Methods We generated a cardiomyocyte-targeted Nox2-transgenic mouse model and studied the effects of in vivo and ex vivo Ang II stimulation, as well as chronic aortic banding. Results Chronic subpressor Ang II infusion induced greater cardiac hypertrophy in transgenic than wild-type mice but unexpectedly enhanced contractile function. Acute Ang II treatment also enhanced contractile function in transgenic hearts in vivo and transgenic cardiomyocytes ex vivo. Ang II–stimulated Nox2 activity increased sarcoplasmic reticulum (SR) Ca2+ uptake in transgenic mice, increased the Ca2+ transient and contractile amplitude, and accelerated cardiomyocyte contraction and relaxation. Elevated Nox2 activity increased phospholamban phosphorylation in both hearts and cardiomyocytes, related to inhibition of protein phosphatase 1 activity. In a model of aortic banding–induced chronic pressure overload, heart function was similarly depressed in transgenic and wild-type mice. Conclusions We identified a novel mechanism in which Nox2 modulates cardiomyocyte SR Ca2+ uptake and contractile function through redox-regulated changes in phospholamban phosphorylation. This mechanism can drive increased contractility in the short term in disease states characterized by enhanced renin-angiotensin system activation. PMID:26184620

  7. Transplantation of adipose tissue-derived stem cells improves cardiac contractile function and electrical stability in a rat myocardial infarction model.

    PubMed

    Gautam, Milan; Fujita, Daiki; Kimura, Kazuhiro; Ichikawa, Hinako; Izawa, Atsushi; Hirose, Masamichi; Kashihara, Toshihide; Yamada, Mitsuhiko; Takahashi, Masafumi; Ikeda, Uichi; Shiba, Yuji

    2015-04-01

    The transplantation of adipose tissue-derived stem cells (ADSCs) improves cardiac contractility after myocardial infarction (MI); however, little is known about the electrophysiological consequences of transplantation. The purpose of this study was to clarify whether the transplantation of ADSCs increases or decreases the incidence of ventricular tachyarrhythmias (VT) in a rat model of MI. MI was induced experimentally by permanent occlusion of the left anterior descending artery of Lewis rats. ADSCs were harvested from GFP-transgenic rats, and were cultured until passage four. ADSCs (10×10(6)) resuspended in 100μL saline or pro-survival cocktail (PSC), which enhances cardiac graft survival, were injected directly into syngeneic rat hearts 1week after MI. The recipients of ADSCs suspended in PSC had a larger graft area compared with those receiving ASDCs suspended in saline at 1week post-transplantation (number of graft cells/section: 148.7±10.6 vs. 22.4±3.4, p<0.05, n=5/group). Thereafter, all ADSC recipients were transplanted with ASDCs in PSC. ADSCs were transplanted into infarcted hearts, and the mechanical and electrophysiological functions were assessed. Echocardiography revealed that ADSC recipients had improved contractile function compared with those receiving PSC vehicle (fractional shortening: 21.1±0.9 vs. 14.1±1.2, p<0.05, n≥12/group). Four weeks post-transplantation, VT was induced via in vivo programmed electrical stimulation. The recipients of ADSCs showed a significantly lower incidence of induced VT compared with the control (31.3% vs. 83.3%, p<0.05, n≥12/group). To understand the electrical activity following transplantation, we performed ex vivo optical mapping using a voltage sensitive dye, and found that ADSC transplantation decreased conduction velocity and its dispersion in the peri-infarct area. These results suggest that ADSC transplantation improved cardiac mechanical and electrophysiological functions in subacute MI. PMID

  8. Adipose stem cell sheets improved cardiac function in the rat myocardial infarction, but did not alter cardiac contractile responses to β-adrenergic stimulation.

    PubMed

    Otsuki, Yuki; Nakamura, Yoshinobu; Harada, Shingo; Yamamoto, Yasutaka; Ogino, Kazuhide; Morikawa, Kumi; Ninomiya, Haruaki; Miyagawa, Shigeru; Sawa, Yoshiki; Hisatome, Ichiro; Nishimura, Motonobu

    2015-01-01

    Adipose stem cells (ASCs) are a source of regenerative cells available for autologous transplantation to hearts. We compared protective actions of ASC sheets on rat myocardial infarction (MI) in comparison with those of skeletal myoblast cell sheets. Their effects on infarcted hearts were evaluated by biological, histochemical as well as physiological analyses. ASC sheets secreted higher concentrations of angiogenic factors (HGF, VEGF, and bFGF; P < 0.05) under normoxic and hypoxic conditions than those of myoblast cell sheets, associated with reduction of cell apoptosis (P < 0.05). Like myoblast cell sheets, ASC sheets improved cardiac function (P < 0.05) and decreased the plasma level of ANP (P < 0.05) in MI hearts. ASC sheets restored cardiac remodeling characterized by fibrosis, cardiac hypertrophy and impaired angiogenesis (P < 0.05), which was associated with increases in angiogenic factors (P < 0.05). In isolated perfused rat hearts, ASC sheets improved both systolic and diastolic functions, which was comparable to cardiac functions of myoblast cell sheets, while both cell sheets failed to restore cardiac contractile response to either isoproterenol, pimobendan or dibutyryl cAMP. These results indicated that ASC sheets improved cardiac function and remodeling of MI hearts mediated by their paracrine action and this improvement was comparable to those by myoblast cell sheets. PMID:25749147

  9. Emerging trends in the pathophysiology of lymphatic contractile function

    PubMed Central

    Chakraborty, Sanjukta; Davis, Michael J.; Muthuchamy, Mariappan

    2015-01-01

    Lymphatic contractile dysfunction is central to a number of pathologies that affect millions of people worldwide. Due to its critical role in the process of inflammation, a dysfunctional lymphatic system also compromises the immune response, further exacerbating a number of inflammation related diseases. Despite the critical physiological functions accomplished by the transport of lymph, a complete understanding of the contractile machinery of the lymphatic system lags far behind that of the blood vasculature. However, there has been a surge of recent research focusing on different mechanisms that underlie both physiological and pathophysiological aspects of lymphatic contractile function. This review summarizes those emerging paradigms that shed some novel insights into the contractile physiology of the lymphatics in normal as well as different disease states. In addition, this review emphasizes the recent progress made in our understanding of various contractile parameters and regulatory elements that contribute to the normal functioning of the lymphatics. PMID:25617600

  10. Effects of regular exercise training on skeletal muscle contractile function

    NASA Technical Reports Server (NTRS)

    Fitts, Robert H.

    2003-01-01

    Skeletal muscle function is critical to movement and one's ability to perform daily tasks, such as eating and walking. One objective of this article is to review the contractile properties of fast and slow skeletal muscle and single fibers, with particular emphasis on the cellular events that control or rate limit the important mechanical properties. Another important goal of this article is to present the current understanding of how the contractile properties of limb skeletal muscle adapt to programs of regular exercise.

  11. Dietary Nitrate and Skeletal Muscle Contractile Function in Heart Failure.

    PubMed

    Coggan, Andrew R; Peterson, Linda R

    2016-08-01

    Heart failure (HF) patients suffer from exercise intolerance that diminishes their ability to perform normal activities of daily living and hence compromises their quality of life. This is due largely to detrimental changes in skeletal muscle mass, structure, metabolism, and function. This includes an impairment of muscle contractile performance, i.e., a decline in the maximal force, speed, and power of muscle shortening. Although numerous mechanisms underlie this reduction in contractility, one contributing factor may be a decrease in nitric oxide (NO) bioavailability. Consistent with this, recent data demonstrate that acute ingestion of NO3 (-)-rich beetroot juice, a source of NO via the NO synthase-independent enterosalivary pathway, markedly increases maximal muscle speed and power in HF patients. This review discusses the role of muscle contractile dysfunction in the exercise intolerance characteristic of HF, and the evidence that dietary NO3 (-) supplementation may represent a novel and simple therapy for this currently underappreciated problem. PMID:27271563

  12. Stable, Covalent Attachment of Laminin to Microposts Improves the Contractility of Mouse Neonatal Cardiomyocytes

    PubMed Central

    2015-01-01

    The mechanical output of contracting cardiomyocytes, the muscle cells of the heart, relates to healthy and disease states of the heart. Culturing cardiomyocytes on arrays of elastomeric microposts can enable inexpensive and high-throughput studies of heart disease at the single-cell level. However, cardiomyocytes weakly adhere to these microposts, which limits the possibility of using biomechanical assays of single cardiomyocytes to study heart disease. We hypothesized that a stable covalent attachment of laminin to the surface of microposts improves cardiomyocyte contractility. We cultured cells on polydimethylsiloxane microposts with laminin covalently bonded with the organosilanes 3-glycidoxypropyltrimethoxysilane and 3-aminopropyltriethoxysilane with glutaraldehyde. We measured displacement of microposts induced by the contractility of mouse neonatal cardiomyocytes, which attach better than mature cardiomyocytes to substrates. We observed time-dependent changes in contractile parameters such as micropost deformation, contractility rates, contraction and relaxation speeds, and the times of contractions. These parameters were affected by the density of laminin on microposts and by the stability of laminin binding to micropost surfaces. Organosilane-mediated binding resulted in higher laminin surface density and laminin binding stability. 3-glycidoxypropyltrimethoxysilane provided the highest laminin density but did not provide stable protein binding with time. Higher surface protein binding stability and strength were observed with 3-aminopropyltriethoxysilane with glutaraldehyde. In cultured cardiomyocytes, contractility rate, contraction speeds, and contraction time increased with higher laminin stability. Given these variations in contractile function, we conclude that binding of laminin to microposts via 3-aminopropyltriethoxysilane with glutaraldehyde improves contractility observed by an increase in beating rate and contraction speed as it occurs during the

  13. Effect of hypokinesia on contractile function of cardiac muscle

    NASA Technical Reports Server (NTRS)

    Meyerson, F. Z.; Kapelko, V. I.; Trikhpoyeva, A. M.; Gorina, M. S.

    1980-01-01

    Rats were subjected to hypokinesia for two months and the contractile function of isolated papillary muscle was studied. Hypokinesia reduced significantly the isotonic contraction rate which depended on the ATPase activity of the myofibrils; it also reduced the rate and index of relaxation which depended on the functional capacity of the Ca(++) pump of the sarcoplasmic reticulum. The maximum force of isometric contraction determined by the quantity of actomyosin bridges in the myofibrils did not change after hypokinesia. This complex of changes is contrary to that observed in adaptation to exercise when the rate of isotonic contraction and relaxation increases while the force of isometric contraction does not change. The possible mechanism of this stability of the contractile force during adaptation and readaptation of the heart is discussed.

  14. Skeletal Muscle Phospholipid Metabolism Regulates Insulin Sensitivity and Contractile Function.

    PubMed

    Funai, Katsuhiko; Lodhi, Irfan J; Spears, Larry D; Yin, Li; Song, Haowei; Klein, Samuel; Semenkovich, Clay F

    2016-02-01

    Skeletal muscle insulin resistance is an early defect in the development of type 2 diabetes. Lipid overload induces insulin resistance in muscle and alters the composition of the sarcoplasmic reticulum (SR). To test the hypothesis that skeletal muscle phospholipid metabolism regulates systemic glucose metabolism, we perturbed choline/ethanolamine phosphotransferase 1 (CEPT1), the terminal enzyme in the Kennedy pathway of phospholipid synthesis. In C2C12 cells, CEPT1 knockdown altered SR phospholipid composition and calcium flux. In mice, diet-induced obesity, which decreases insulin sensitivity, increased muscle CEPT1 expression. In high-fat diet-fed mice with skeletal muscle-specific knockout of CEPT1, systemic and muscle-based approaches demonstrated increased muscle insulin sensitivity. In CEPT1-deficient muscles, an altered SR phospholipid milieu decreased sarco/endoplasmic reticulum Ca(2+) ATPase-dependent calcium uptake, activating calcium-signaling pathways known to improve insulin sensitivity. Altered muscle SR calcium handling also rendered these mice exercise intolerant. In obese humans, surgery-induced weight loss increased insulin sensitivity and decreased skeletal muscle CEPT1 protein. In obese humans spanning a spectrum of metabolic health, muscle CEPT1 mRNA was inversely correlated with insulin sensitivity. These results suggest that high-fat feeding and obesity induce CEPT1, which remodels the SR to preserve contractile function at the expense of insulin sensitivity. PMID:26512026

  15. Recovery in skeletal muscle contractile function after prolonged hindlimb immobilization

    NASA Technical Reports Server (NTRS)

    Fitts, R. H.; Brimmer, C. J.

    1985-01-01

    The effect of three-month hindlimb immobilization (IM) in rats on contractile properties of slow-twitch soleus (SOL), fast-twitch extensor digitorum longus, and fast-twitch superficial region of the vastus lateralis were measured after 0, 14, 28, 60, and 90 days of recovery on excized, horizontally suspended muscles stimulated electrically to maximal twitch tension. IM caused decreases in muscle-to-body weight ratios for all muscles, with no complete recovery even after 90 days. The contractile properties of the fast-twitch muscles were less affected by IM than those of the slow-twitch SOL. The SOL isometric twitch duration was shortened, due to reduced contraction and half-relaxation time, both of which returned to control levels after 14 days of recovery. The peak tetanic tension, P(O), g/sq cm,, decreased with IM by 46 percent in the SOL, but recovered by the 28th day. The maximum shortening velocity was not altered by IM in any of the muscles. Thus, normal contractile function could recover after prolonged limb IM.

  16. Mitochondria-targeted antioxidant preserves contractile properties and mitochondrial function of skeletal muscle in aged rats

    PubMed Central

    Javadov, Sabzali; Jang, Sehwan; Rodriguez-Reyes, Natividad; Rodriguez-Zayas, Ana E.; Hernandez, Jessica Soto; Krainz, Tanja; Wipf, Peter; Frontera, Walter

    2015-01-01

    Mitochondrial dysfunction plays a central role in the pathogenesis of sarcopenia associated with a loss of mass and activity of skeletal muscle. In addition to energy deprivation, increased mitochondrial ROS damage proteins and lipids in aged skeletal muscle. Therefore, prevention of mitochondrial ROS is important for potential therapeutic strategies to delay sarcopenia. This study elucidates the pharmacological efficiency of the new developed mitochondria-targeted ROS and electron scavenger, XJB-5-131 (XJB) to restore muscle contractility and mitochondrial function in aged skeletal muscle. Male adult (5-month old) and aged (29-month old) Fischer Brown Norway (F344/BN) rats were treated with XJB for four weeks and contractile properties of single skeletal muscle fibres and activity of mitochondrial ETC complexes were determined at the end of the treatment period. XJB-treated old rats showed higher muscle contractility associated with prevention of protein oxidation in both muscle homogenate and mitochondria compared with untreated counterparts. XJB-treated animals demonstrated a high activity of the respiratory complexes I, III, and IV with no changes in citrate synthase activity. These data demonstrate that mitochondrial ROS play a causal role in muscle weakness, and that a ROS scavenger specifically targeted to mitochondria can reverse age-related alterations of mitochondrial function and improve contractile properties in skeletal muscle. PMID:26415224

  17. Mitochondria-targeted antioxidant preserves contractile properties and mitochondrial function of skeletal muscle in aged rats.

    PubMed

    Javadov, Sabzali; Jang, Sehwan; Rodriguez-Reyes, Natividad; Rodriguez-Zayas, Ana E; Soto Hernandez, Jessica; Krainz, Tanja; Wipf, Peter; Frontera, Walter

    2015-11-24

    Mitochondrial dysfunction plays a central role in the pathogenesis of sarcopenia associated with a loss of mass and activity of skeletal muscle. In addition to energy deprivation, increased mitochondrial ROS damage proteins and lipids in aged skeletal muscle. Therefore, prevention of mitochondrial ROS is important for potential therapeutic strategies to delay sarcopenia. This study elucidates the pharmacological efficiency of the new developed mitochondria-targeted ROS and electron scavenger, XJB-5-131 (XJB) to restore muscle contractility and mitochondrial function in aged skeletal muscle. Male adult (5-month old) and aged (29-month old) Fischer Brown Norway (F344/BN) rats were treated with XJB for four weeks and contractile properties of single skeletal muscle fibres and activity of mitochondrial ETC complexes were determined at the end of the treatment period. XJB-treated old rats showed higher muscle contractility associated with prevention of protein oxidation in both muscle homogenate and mitochondria compared with untreated counterparts. XJB-treated animals demonstrated a high activity of the respiratory complexes I, III, and IV with no changes in citrate synthase activity. These data demonstrate that mitochondrial ROS play a causal role in muscle weakness, and that a ROS scavenger specifically targeted to mitochondria can reverse age-related alterations of mitochondrial function and improve contractile properties in skeletal muscle. PMID:26415224

  18. Stretch-induced increase in cardiac contractility is independent of myocyte Ca2+ while block of stretch channels by streptomycin improves contractility after ischemic stunning

    PubMed Central

    Rhodes, Samhita S; Camara, Amadou K S; Aldakkak, Mohammed; Heisner, James S; Stowe, David F

    2015-01-01

    Stretching the cardiac left ventricle (LV) enhances contractility but its effect on myoplasmic [Ca2+] is controversial. We measured LV pressure (LVP) and [Ca2+] as a function of intra-LV stretch in guinea pig intact hearts before and after 15 min global stunning ± perfusion with streptomycin (STM), a stretch-activated channel blocker. LV wall [Ca2+] was measured by indo-1 fluorescence and LVP by a saline-filled latex balloon inflated in 50 μL steps to stretch the LV. We implemented a mathematical model to interpret cross-bridge dynamics and myofilament Ca2+ responsiveness from the instantaneous relationship between [Ca2+] and LVP ± stretching. We found that: (1) stretch enhanced LVP but not [Ca2+] before and after stunning in either control (CON) and STM groups, (2) after stunning [Ca2+] increased in both groups although higher in STM versus CON (56% vs. 39%), (3) STM-enhanced LVP after stunning compared to CON (98% vs. 76% of prestunning values), and (4) stretch-induced effects on LVP were independent of [Ca2+] before or after stunning in both groups. Mathematical modeling suggested: (1) cooperativity in cross-bridge kinetics and myofilament Ca2+ handling is reduced after stunning in the unstretched heart, (2) stunning results in depressed myofilament Ca2+ sensitivity in the presence of attached cross-bridges regardless of stretch, and (3) the initial mechanism responsible for increased contractility during stretch may be enhanced formation of cross-bridges. Thus stretch-induced enhancement of contractility is not due to increased [Ca2+], whereas enhanced contractility after stunning in STM versus CON hearts results from improved Ca2+ handling and/or enhanced actinomyosin cross-bridge cycling. PMID:26290532

  19. Dietary nitrate improves cardiac contractility via enhanced cellular Ca²⁺ signaling.

    PubMed

    Pironti, Gianluigi; Ivarsson, Niklas; Yang, Jiangning; Farinotti, Alex Bersellini; Jonsson, William; Zhang, Shi-Jin; Bas, Duygu; Svensson, Camilla I; Westerblad, Håkan; Weitzberg, Eddie; Lundberg, Jon O; Pernow, John; Lanner, Johanna; Andersson, Daniel C

    2016-05-01

    The inorganic anion nitrate (NO3 (-)), which is naturally enriched in certain vegetables (e.g., spinach and beetroot), has emerged as a dietary component that can regulate diverse bodily functions, including blood pressure, mitochondrial efficiency, and skeletal muscle force. It is not known if dietary nitrate improves cardiac contractility. To test this, mice were supplemented for 1-2 weeks with sodium nitrate in the drinking water at a dose similar to a green diet. The hearts from nitrate-treated mice showed increased left ventricular pressure and peak rate of pressure development as measured with the Langendorff heart technique. Cardiomyocytes from hearts of nitrate-treated and control animals were incubated with the fluorescent indicator Fluo-3 to measure cytoplasmic free [Ca(2+)] and fractional shortening. Cardiomyocytes from nitrate-treated mice displayed increased fractional shortening, which was linked to larger Ca(2+) transients. Moreover, nitrate hearts displayed increased protein expression of the L-type Ca(2+) channel/dihydropyridine receptor and peak L-type Ca(2+) channel currents. The nitrate-treated hearts displayed increased concentration of cAMP but unchanged levels of cGMP compared with controls. These findings provide the first evidence that dietary nitrate can affect the expression of important Ca(2+) handling proteins in the heart, resulting in increased cardiomyocyte Ca(2+) signaling and improved left ventricular contractile function. Our observation shows that dietary nitrate impacts cardiac function and adds understanding to inorganic nitrate as a physiological modulator. PMID:27071401

  20. Catecholamines and myocardial contractile function during hypodynamia and with an altered thyroid hormone balance

    NASA Technical Reports Server (NTRS)

    Pruss, G. M.; Kuznetsov, V. I.; Zhilinskaya, A. A.

    1980-01-01

    The dynamics of catecholamine content and myocardial contractile function during hypodynamia were studied in 109 white rats whose motor activity was severely restricted for up to 30 days. During the first five days myocardial catecholamine content, contractile function, and physical load tolerance decreased. Small doses of thyroidin counteracted this tendency. After 15 days, noradrenalin content and other indices approached normal levels and, after 30 days, were the same as control levels, although cardiac functional reserve was decreased. Thyroidin administration after 15 days had no noticeable effect. A detailed table shows changes in 17 indices of myocardial contractile function during hypodynamia.

  1. Effect of a Periodized Power Training Program on the Functional Performances and Contractile Properties of the Quadriceps in Sprinters

    ERIC Educational Resources Information Center

    Kamandulis, Sigitas; Skurvydas, Albertas; Brazaitis, Marius; Stanislovaitis, Aleksas; Duchateau, Jacques; Stanislovaitiene, Jurate

    2012-01-01

    Our purpose was to compare the effect of a periodized preparation consisting of power endurance training and high-intensity power training on the contractile properties of the quadriceps muscle and functional performances in well trained male sprinters (n = 7). After 4 weeks of high-intensity power training, 60-m sprint running time improved by an…

  2. Feeding the fibrillating heart: Dichloroacetate improves cardiac contractile dysfunction following VF.

    PubMed

    Azam, Mohammed Ali; Wagg, Cory S; Massé, Stéphane; Farid, Talha; Lai, Patrick F H; Kusha, Marjan; Asta, John; Jaimes, Rafael; Kuzmiak-Glancy, Sarah; Kay, Matthew W; Lopaschuk, Gary D; Nanthakumar, Kumaraswamy

    2015-11-01

    Ventricular fibrillation (VF) is an important cause of sudden cardiac arrest following myocardial infarction. Following resuscitation from VF, decreased cardiac contractile function is a common problem. During and following myocardial ischemia, decreased glucose oxidation, increased anaerobic glycolysis for cardiac energy production are harmful and energetically expensive. The objective of the present study is to determine the effects of dichloroacetate (DCA), a glucose oxidation stimulator, on cardiac contractile dysfunction following ischemia-induced VF. Male Sprague-Dawley rat hearts were Langendorff perfused in Tyrode's buffer. Once stabilized, hearts were subjected to 15 min of global ischemia and 5 min of aerobic reperfusion in the presence or absence of DCA. At the 6th min of reperfusion, VF was induced electrically, and terminated. Left ventricular (LV) pressure was measured using a balloon. Pretreatment with DCA significantly improved post-VF left ventricular developed pressure (LVDP) and dp/dtmax. In DCA-pretreated hearts, post-VF lactate production and pyruvate dehydrogenase (PDH) phosphorylation were significantly reduced, indicative of stimulated glucose oxidation, and inhibited anaerobic glycolysis by activation of PDH. Epicardial NADH fluorescence was increased during global ischemia above preischemic levels, but decreased below preischemia levels following VF, with no differences between nontreated controls and DCA-pretreated hearts, whereas DCA pretreatment increased NADH production in nonischemic hearts. With exogenous fatty acids (FA) added to the perfusion solution, DCA pretreatment also resulted in improvements in post-VF LVDP and dp/dtmax, indicating that the presence of exogenous FA did not affect the beneficial actions of DCA. In conclusion, enhancement of PDH activation by DCA mitigates cardiac contractile dysfunction following ischemia-induced VF. PMID:26342067

  3. Muscle fatigue in frog semitendinosus: alterations in contractile function.

    PubMed

    Thompson, L V; Balog, E M; Riley, D A; Fitts, R H

    1992-06-01

    The purpose of this study was to characterize the contractile properties of the frog semitendinosus (ST) muscle before and during recovery from fatigue, to relate the observed functional changes to alterations in specific steps in the crossbridge model of muscle contraction, and to determine how fatigue affects the force-frequency relationship. The frog ST (22 degrees C) was fatigued by direct electrical stimulation with 100-ms 150-Hz trains at 1/s for 5 min. The fatigue protocol reduced peak twitch (Pt) and tetanic (Po) force to 32 and 8.5% of initial force, respectively. The decline in Pt was less than Po, in part due to a prolongation in the isometric contraction time (CT), which increased to 300% of the initial value. The isometric twitch duration was greatly prolonged as reflected by the lengthened CT and the 800% increase in the one-half relaxation time (1/2RT). Both Pt and Po showed a biphasic recovery, a rapid initial phase (2 min) followed by a slower (40 min) return to the prefatigue force. CT and 1/2RT also recovered in two phases, returning to 160 and 265% of control in the first 5 min. CT returned to the prefatigue value between 35 and 40 min, whereas even at 60 min 1/2RT was 133% of control. The maximal velocity of shortening, determined by the slack test, was significantly reduced [from 6.7 +/- 0.5 to 2.5 +/- 0.4 optimal muscle length/s] at fatigue. The force-frequency relationship was shifted to the left, so that optimal frequency for generating Po was reduced.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1535482

  4. Muscle fatigue in frog semitendinosus: alterations in contractile function

    NASA Technical Reports Server (NTRS)

    Thompson, L. V.; Balog, E. M.; Riley, D. A.; Fitts, R. H.

    1992-01-01

    The purpose of this study was to characterize the contractile properties of the frog semitendinosus (ST) muscle before and during recovery from fatigue, to relate the observed functional changes to alterations in specific steps in the crossbridge model of muscle contraction, and to determine how fatigue affects the force-frequency relationship. The frog ST (22 degrees C) was fatigued by direct electrical stimulation with 100-ms 150-Hz trains at 1/s for 5 min. The fatigue protocol reduced peak twitch (Pt) and tetanic (Po) force to 32 and 8.5% of initial force, respectively. The decline in Pt was less than Po, in part due to a prolongation in the isometric contraction time (CT), which increased to 300% of the initial value. The isometric twitch duration was greatly prolonged as reflected by the lengthened CT and the 800% increase in the one-half relaxation time (1/2RT). Both Pt and Po showed a biphasic recovery, a rapid initial phase (2 min) followed by a slower (40 min) return to the prefatigue force. CT and 1/2RT also recovered in two phases, returning to 160 and 265% of control in the first 5 min. CT returned to the prefatigue value between 35 and 40 min, whereas even at 60 min 1/2RT was 133% of control. The maximal velocity of shortening, determined by the slack test, was significantly reduced [from 6.7 +/- 0.5 to 2.5 +/- 0.4 optimal muscle length/s] at fatigue. The force-frequency relationship was shifted to the left, so that optimal frequency for generating Po was reduced.(ABSTRACT TRUNCATED AT 250 WORDS).

  5. Vascular Endothelial Growth Factor Prevents Apoptosis and Preserves Contractile Function in Hypertrophied Infant Heart

    PubMed Central

    Friehs, Ingeborg; Barillas, Rodrigo; Vasilyev, Nikolay V.; Roy, Nathalie; McGowan, Francis X.; del Nido, Pedro J.

    2012-01-01

    Background Cardiac hypertrophy is an adaptive response to increased workload that, if unrelieved, leads to heart failure. It has been reported that cardiomyocyte apoptosis contributes to failure, and that vascular endothelial growth factor (VEGF) treatment of hypertrophied myocardium increases capillary density and improves myocardial perfusion. In this study we hypothesized that VEGF treatment reduces cardiomyocyte apoptosis and thereby preserves myocardial contractile function. Methods and Results Newborn rabbits underwent aortic banding. At 4 and 6 weeks of age, hypertrophied animals were treated with intrapericardial administration of recombinant VEGF protein. Three groups of animals were investigated: age-matched controls (C), untreated hypertrophied (H), and VEGF-treated hypertrophied hearts (T). Cardiomyocyte apoptosis was determined by TUNEL staining and PARP cleavage (immunoblotting of nuclear extracts) and cardiac function by transthoracic echocardiography. Death attributable to severe heart failure occurred in 14 of 43 untreated and 2 of 29 VEGF-treated animals (P<0.01). TUNEL-positive cardiomyocyte nuclei (n/1000 nuclei) were significantly increased in untreated hearts at 5 weeks (H: 10±1.8 versus T: 3±0.7) and at 7 weeks (H: 13±3.6 versus T: 5±1.5; P<0.05). Increased apoptosis in untreated hypertrophy was also confirmed by the presence of PARP cleavage (H: 74±7 versus T: 41±4 arbitrary densitometry units; P<0.05). VEGF treatment preserved left ventricular mass, prevented dilation (T: 1.01±0.06 versus H: 0.77±0.07; P<0.05), and preserved contractility indices compared with untreated hearts. Conclusions Lack of adaptive capillary growth impairs myocardial perfusion and substrate delivery in hypertrophying myocardium. VEGF treatment reduces myocardial apoptosis and prolongs survival in a model of severe progressive left ventricular hypertrophy. Promoting capillary growth with VEGF reduces apoptosis, preserves myocardial contractile function, and

  6. The role of microtubules in contractile ring function

    NASA Technical Reports Server (NTRS)

    Conrad, A. H.; Paulsen, A. Q.; Conrad, G. W.; Spooner, B. S. (Principal Investigator)

    1992-01-01

    During cytokinesis, a cortical contractile ring forms around a cell, constricts to a stable tight neck and terminates in separation of the daughter cells. At first cleavage, Ilyanassa obsoleta embryos form two contractile rings simultaneously. The cleavage furrow (CF), in the animal hemisphere between the spindle poles, constricts to a stable tight neck and separates the daughter cells. The third polar lobe constriction (PLC-3), in the vegetal hemisphere below the spindle, constricts to a transient tight neck, but then relaxes, allowing the polar lobe cytoplasm to merge with one daughter cell. Eggs exposed to taxol, a drug that stabilizes microtubules, before the CF or the PLC-3 develop, fail to form CFs, but form stabilized tight PLCs. Eggs exposed to taxol at the time of PLC-3 formation develop varied numbers of constriction rings in their animal hemispheres and one PLC in their vegetal hemisphere, none of which relax. Eggs exposed to taxol after PLC-3 initiation form stabilized tight CFs and PLCs. At maximum constriction, control embryos display immunolocalization of nonextractable alpha-tubulin in their CFs, but not in their PLCs, and reveal, via electron microscopy, many microtubules extending through their CFs, but not through their PLCs. Embryos which form stabilized tightly constricted CFs and PLCs in the presence of taxol display immunolocalization of nonextractable alpha-tubulin in both constrictions and show many polymerized microtubules extending through both CFs and PLCs. These results suggest that the extension of microtubules through a tight contractile ring may be important for stabilizing that constriction and facilitating subsequent cytokinesis.

  7. Effects of Modified Parvalbumin EF-Hand Motifs on Cardiac Myocyte Contractile Function.

    PubMed

    Asp, Michelle L; Sjaastad, Frances V; Siddiqui, Jalal K; Davis, Jonathan P; Metzger, Joseph M

    2016-05-10

    Cardiac gene delivery of parvalbumin (Parv), an EF-hand Ca(2+) buffer, has been studied as a therapeutic strategy for diastolic heart failure, in which slow Ca(2+) reuptake is an important contributor. A limitation of wild-type (WT) Parv is the significant trade-off between faster relaxation and blunted contraction amplitude, occurring because WT-Parv sequesters Ca(2+) too early in the cardiac cycle and prematurely truncates sarcomere shortening in the facilitation of rapid relaxation. We recently demonstrated that an E → Q substitution (ParvE101Q) at amino acid 12 of the EF-hand Ca(2+)/Mg(2+) binding loop disrupts bidentate Ca(2+) binding, reducing Ca(2+) affinity by 99-fold and increasing Mg(2+) affinity twofold. ParvE101Q caused faster relaxation and not only preserved contractility, but unexpectedly increased it above untreated myocytes. To gain mechanistic insight into the increased contractility, we focused here on amino acid 12 of the EF-hand motif. We introduced an E → D substitution (ParvE101D) at this site, which converts bidentate Ca(2+) coordination to monodentate coordination. ParvE101D decreased Ca(2+) affinity by 114-fold and increased Mg(2+) affinity 28-fold compared to WT-Parv. ParvE101D increased contraction amplitude compared to both untreated myocytes and myocytes with ParvE101Q, with limited improvement in relaxation. Additionally, ParvE101D increased spontaneous contractions after pacing stress. ParvE101D also increased Ca(2+) transient peak height and was diffusely localized around the Z-line of the sarcomere, suggesting a Ca(2+)-dependent mechanism of enhanced contractility. Sarcoplasmic reticulum Ca(2+) load was not changed with ParvE101D, but postpacing Ca(2+) waves were increased. Together, these data show that inverted Ca(2+)/Mg(2+) binding affinities of ParvE101D increase myocyte contractility through a Ca(2+)-dependent mechanism without altering sarcoplasmic reticulum Ca(2+) load and by increasing unstimulated contractions and Ca(2

  8. Dietary interaction of high fat and marginal copper deficiency on cardiac contractile function

    Technology Transfer Automated Retrieval System (TEKTRAN)

    High fat and copper deficient diets impair heart function leading to cardio hypertrophy, increased lipid droplet volume and compromised contractile function, resembling liptoxic cardiac dysfunction. However, the combined effect of the two on cardiac function is unknown. The purpose or objective of t...

  9. Recovery time course in contractile function of fast and slow skeletal muscle after hindlimb immobilization

    NASA Technical Reports Server (NTRS)

    Witzmann, F. A.; Kim, D. H.; Fitts, R. H.

    1982-01-01

    The present study was undertaken to characterize the time course and extent of recovery in the isometric and isotonic contractile properties of fast and slow skeletal muscle following 6 wk of hindlimb immobilization. Female Sprague-Dawley rats were randomly assigned to an immobilized group or a control group. The results of the study show that fast and slow skeletal muscles possess the ability to completely recover normal contractile function following 6 wk of hindlimb immobilization. The rate of recovery is dependent on the fiber type composition of the affected muscle.

  10. Circadian rhythms in myocardial metabolism and contractile function; influence of workload and oleate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Multiple extra-cardiac stimuli, such as workload and circulating nutrients (e.g., fatty acids), known to influence myocardial metabolism and contractile function exhibit marked circadian rhythms. The aim of the present study was to investigate whether the rat heart exhibits circadian rhythms in its ...

  11. Skeletal muscle morphology and contractile function in relation to muscle denervation in diabetic neuropathy

    PubMed Central

    Major, Brendan; Kimpinski, Kurt; Doherty, Timothy J.; Rice, Charles L.

    2013-01-01

    The objective of the study was to assess the effects of diabetic polyneuropathy (DPN) on muscle contractile properties in humans, and how these changes are related to alterations in muscle morphology and denervation. Patients with DPN (n = 12) were compared with age- and sex-matched controls (n = 12). Evoked and voluntary contractile properties, including stimulated twitch responses and maximal voluntary contractions, of the dorsiflexor muscles were assessed using an isometric ankle dynamometer. Motor unit number estimates (MUNE) of the tibialis anterior (TA) were performed via quantitative electromyography and decomposition-enhanced spike-triggered averaging. Peak tibialis anterior (TA) cross-sectional area (CSA; cm2), and relative proportion of contractile to noncontractile tissue (%) was determined from magnetic resonance images. Patients with DPN demonstrated decreased strength (−35%) and slower (−45%) dorsiflexion contractile properties for both evoked and voluntary contractions (P < 0.05). These findings were not accounted for by differences in voluntary activation (P > 0.05) or antagonist coactivation (P > 0.05). Additionally, patients with DPN were weaker when strength was normalized to TA total CSA (−30%; P < 0.05) or contractile tissue CSA (−26%; P < 0.05). In the DPN patient group, TA MUNEs were negatively related to both % noncontractile tissue (P < 0.05; r = 0.72) and twitch half-relaxation time (P < 0.05; r = 0.60), whereas no relationships were found between these variables in controls (P > 0.05). We conclude that patients with DPN demonstrated reduced strength and muscle quality as well as contractile slowing. This process may contribute to muscle power loss and functional impairments reported in patients with DPN, beyond the loss of strength commonly observed. PMID:24356519

  12. Lidocaine Enhances Contractile Function of Ischemic Myocardial Regions in Mouse Model of Sustained Myocardial Ischemia

    PubMed Central

    Kania, Gabriela; Osto, Elena; Jakob, Philipp; Krasniqi, Nazmi; Beck-Schimmer, Beatrice; Blyszczuk, Przemyslaw; Eriksson, Urs

    2016-01-01

    Rationale Perioperative myocardial ischemia is common in high-risk patients. The use of interventional revascularisation or even thrombolysis is limited in this patient subset due to exceedingly high bleeding risks. Blockade of voltage-gated sodium channels (VGSC) with lidocaine had been suggested to reduce infarct size and cardiomyocyte cell death in ischemia/reperfusion models. However, the impact of lidocaine on cardiac function during sustained ischemia still remains unclear. Methods Sustained myocardial ischemia was induced by ligation of the left anterior descending artery in 12–16 weeks old male BALB/c mice. Subcutaneous lidocaine (30 mg/kg) was used to block VGSC. Cardiac function was quantified at baseline and at 72h by conventional and speckle-tracking based echocardiography to allow high-sensitivity in vivo phenotyping. Infarct size and cardiomyocyte cell death were assessed post mortem histologically and indirectly using troponin measurements. Results Ischemia strongly impaired both, global systolic and diastolic function, which were partially rescued in lidocaine treated in mice. No differences regarding infarct size and cardiomyocyte cell death were observed. Mechanistically, and as shown with speckle-tracking analysis, lidocaine specifically improves residual contractility in the ischemic but not in the remote, non-ischemic myocardium. Conclusion VGSC blockade with lidocaine rescues function of ischemic myocardium as a potential bridging to revascularisation in the setting of perioperative myocardial ischemia. PMID:27140425

  13. Vinculin network–mediated cytoskeletal remodeling regulates contractile function in the aging heart

    PubMed Central

    Kaushik, Gaurav; Spenlehauer, Alice; Sessions, Ayla O.; Trujillo, Adriana S.; Fuhrmann, Alexander; Fu, Zongming; Venkatraman, Vidya; Pohl, Danielle; Tuler, Jeremy; Wang, Mingyi; Lakatta, Edward G.; Ocorr, Karen; Bodmer, Rolf; Bernstein, Sanford I.; Van Eyk, Jennifer E.; Cammarato, Anthony; Engler, Adam J.

    2015-01-01

    The human heart is capable of functioning for decades despite minimal cell turnover or regeneration, suggesting that molecular alterations help sustain heart function with age. However, identification of compensatory remodeling events in the aging heart remains elusive. We present the cardiac proteomes of young and old rhesus monkeys and rats, from which we show that certain age-associated remodeling events within the cardiomyocyte cytoskeleton are highly conserved and beneficial rather than deleterious. Targeted transcriptomic analysis in Drosophila confirmed conservation and implicated vinculin as a unique molecular regulator of cardiac function during aging. Cardiac-restricted vinculin overexpression reinforced the cortical cytoskeleton and enhanced myofilament organization, leading to improved contractility and hemodynamic stress tolerance in healthy and myosin-deficient fly hearts. Moreover, cardiac-specific vinculin overexpression increased median life span by more than 150% in flies. A broad array of potential therapeutic targets and regulators of age-associated modifications, specifically for vinculin, are presented. These findings suggest that the heart has molecular mechanisms to sustain performance and promote longevity, which may be assisted by therapeutic intervention to ameliorate the decline of function in aging patient hearts. PMID:26084806

  14. The role of mechanotransduction on vascular smooth muscle myocytes' [corrected] cytoskeleton and contractile function.

    PubMed

    Ye, George J C; Nesmith, Alexander P; Parker, Kevin Kit

    2014-09-01

    Smooth muscle (SM) exhibits a highly organized structural hierarchy that extends over multiple spatial scales to perform a wide range of functions at the cellular, tissue, and organ levels. Early efforts primarily focused on understanding vascular SM (VSM) function through biochemical signaling. However, accumulating evidence suggests that mechanotransduction, the process through which cells convert mechanical stimuli into biochemical cues, is requisite for regulating contractility. Cytoskeletal proteins that comprise the extracellular, intercellular, and intracellular domains are mechanosensitive and can remodel their structure and function in response to external mechanical cues. Pathological stimuli such as malignant hypertension can act through the same mechanotransductive pathways to induce maladaptive remodeling, leading to changes in cellular shape and loss of contractile function. In both health and disease, the cytoskeletal architecture integrates the mechanical stimuli and mediates structural and functional remodeling in the VSM. PMID:25125187

  15. The role of mechanotransduction on vascular smooth muscle myocytes cytoskeleton and contractile function

    PubMed Central

    Ye, George J.C.; Nesmith, Alexander P.; Parker, Kevin Kit

    2016-01-01

    Smooth muscle exhibits a highly organized structural hierarchy that extends over multiple spatial scales to perform a wide range of functions at the cellular, tissue, and organ levels. Early efforts primarily focused on understanding vascular smooth muscle function through biochemical signaling. However, accumulating evidence suggests that mechanotransduction, the process through which cells convert mechanical stimuli into biochemical cues, is requisite for regulating contractility. Cytoskeletal proteins that comprise the extracellular, intercellular, and intracellular domains are mechanosensitive and can remodel their structure and function in response to external mechanical cues. Pathological stimuli such as malignant hypertension can act through the same mechanotransductive pathways to induce maladaptive remodeling, leading to changes in cellular shape and loss of contractile function. In both health and disease, the cytoskeletal architecture integrates the mechanical stimuli and mediates structural and functional remodeling in the vascular smooth muscle. PMID:25125187

  16. Utilization of microscale silicon cantilevers to assess cellular contractile function in vitro

    PubMed Central

    Smith, Alec S.T.; Long, Christopher J.; McAleer, Christopher; Bobbitt, Nathaniel; Srinivasan, Balaji; Hickman, James J.

    2016-01-01

    The development of more predictive and biologically relevant in vitro assays is predicated on the advancement of versatile cell culture systems which facilitate the functional assessment of the seeded cells. To that end, microscale cantilever technology offers a platform with which to measure the contractile functionality of a range of cell types, including skeletal, cardiac and smooth muscle cells, through assessment of contraction induced substrate bending. Application of multiplexed cantilever arrays provides the means to develop moderate to high-throughput protocols for assessing drug efficacy and toxicity, disease phenotype and progression, as well as neuromuscular and other cell-cell interactions. This manuscript provides the details for fabricating reliable cantilever arrays for this purpose, and the methods required to successfully culture cells on these surfaces. Further description is provided on the steps necessary to perform functional analysis of contractile cell types maintained on such arrays using a novel laser and photo-detector system. The representative data provided highlights the precision and reproducible nature of the analysis of contractile function possible using this system, as well as the wide range of studies to which such technology can be applied. Successful widespread adoption of this system could provide investigators with the means to perform rapid, low cost functional studies in vitro, leading to more accurate predictions of tissue performance, disease development and response to novel therapeutic treatment. PMID:25350792

  17. An Acanthamoeba castellanii metacaspase associates with the contractile vacuole and functions in osmoregulation.

    PubMed

    Saheb, Entsar; Trzyna, Wendy; Bush, John

    2013-03-01

    Acanthamoeba castellanii is a free-living protozoan. Some strains are opportunistic pathogens. A type-I metacaspase was identified in A. castellanii (Acmcp) and was shown to be expressed through the encystation process. The model organism, Dictyostelium discoideum, has been used here as a model for studying these caspase-like proteins. Separate cell lines expressing a GFP-tagged version of the full length Acmcp protein, as well as a deletion proline region mutant of Acmcp protein (GFP-Acmcp-dpr), have been introduced into D. discoideum. Both mutants affect the cellular metabolism, characterized by an increase in the growth rate. Microscopic imaging revealed an association between Acmcp and the contractile vacuole system in D. discoideum. The treatment of cells with selected inhibitors in different environments added additional support to these findings. This evidence shows that Acmcp plays an important role in contractile vacuole regulation and mediated membrane trafficking in D. discoideum. Additionally, the severe defect in contractile vacuole function in GFP-Acmcp-dpr mutant cells suggests that the proline-rich region in Acmcp has an essential role in binding this protein with other partners to maintain this process. Furthermore, Yeast two-hybrid system identified there are weak interactions of the Dictyostelium contractile vacuolar proteins, including Calmodulin, RabD, Rab11 and vacuolar proton ATPase, with Acmcp protein. Taken together, our findings suggest that A. castellanii metacaspase associate with the contractile vacuole and have an essential role in cell osmoregulation, which contributes to its attractiveness as a possible target for treatment therapies against A. castellanii infection. PMID:23274641

  18. In vivo assessment of contractile strength distinguishes differential gene function in skeletal muscle of zebrafish larvae.

    PubMed

    Martin, Brit L; Gallagher, Thomas L; Rastogi, Neha; Davis, Jonathan P; Beattie, Christine E; Amacher, Sharon L; Janssen, Paul M L

    2015-10-01

    The accessible genetics and extensive skeletal musculature of the zebrafish make it a versatile and increasingly used model for studying muscle contraction. We here describe the development of an in vivo assay for measuring the contractile force of intact zebrafish at the larval stage. In addition, as proof of applicability, we have used this assay to quantify contractile strength of zebrafish larvae in a morphant model of deranged rbfox function. Average maximum tetanic (180 Hz) whole body forces produced by wild-type larvae at 2, 3, 4, and 5 days postfertilization amounted to 3.0, 7.2, 9.1, and 10.8 mN, respectively. To compare at potentially different stages of muscle development, we developed an immunohistological assay for empirically determining the cross-sectional area of larval trunk skeletal muscle to quantify muscle-specific force per cross-sectional area. At 4-5 days postfertilization, specific force amounts to ∼ 300 mN/mm(2), which is similar to fully developed adult mammalian skeletal muscle. We used these assays to measure contractile strength in zebrafish singly or doubly deficient for two rbfox paralogs, rbfox1l and rbfox2, which encode RNA-binding factors shown previously to modulate muscle function and muscle-specific splicing. We found rbfox2 morphants produce maximal tetanic forces similar to wild-type larvae, whereas rbfox1l morphants demonstrate significantly impaired function. rbfox1l/rbfox2 morphants are paralyzed, and their lack of contractile force production in our assay suggests that paralysis is a muscle-autonomous defect. These quantitative functional results allow measurement of muscle-specific phenotypes independent of neural input. PMID:26251513

  19. Contractile function of the myocardium with prolonged hypokinesia in patients with surgical tuberculosis

    NASA Technical Reports Server (NTRS)

    Zakutayeva, V. P.; Matiks, N. I.

    1978-01-01

    The changes in the myocardial contractile function with hypokinesia in surgical tuberculosis patients are discussed. The phase nature of the changes is noted, specifically the changes in the various systoles, diastole, and other parts of the cardiac cycle. The data compare these changes during confinement in bed with no motor activity to and with a return to motor activity after leaving the in-bed regimen.

  20. Contractile function of single muscle fibers after hindlimb suspension

    NASA Technical Reports Server (NTRS)

    Gardetto, P. R.; Schluter, J. M.; Fitts, R. H.

    1989-01-01

    The effects of two weeks of hind-limb suspension (HS) on the functional properties of slow-twitch and fast-twitch single fibers isolated from the predominantly slow-twitch soleus and fast-twitch gastrocnemius of the suspended leg of rats were investigated. Single fibers were suspended between a motor arm and force transducer, and, after their functional properties were studied, the fiber type was established by the myosin heavy chain analysis. It was found that, after HS, the greatest decrease in diameter and a reduction in peak tension occurred in slow-twitch fibers from soleus, followed by slow-twitch fibers from gastrocnemius. Fast-twitch fibers from the red gastrocnemius showed a significant reduction in diameter but no change in peak tension. No effect of HS was observed on the diameter of the fast-twitch fibers from the white gastsrocnemius (which is known to contain 87 percent fast glycolytic fibers).

  1. Contractile function is unaltered in diaphragm from mice lacking calcium release channel isoform 3

    NASA Technical Reports Server (NTRS)

    Clancy, J. S.; Takeshima, H.; Hamilton, S. L.; Reid, M. B.

    1999-01-01

    Skeletal muscle expresses at least two isoforms of the calcium release channel in the sarcoplasmic reticulum (RyR1 and RyR3). Whereas the function of RyR1 is well defined, the physiological significance of RyR3 is unclear. Some authors have suggested that RyR3 participates in excitation-contraction coupling and that RyR3 may specifically confer resistance to fatigue. To test this hypothesis, we measured contractile function of diaphragm strips from adult RyR3-deficient mice (exon 2-targeted mutation) and their heterozygous and wild-type littermates. In unfatigued diaphragm, there were no differences in isometric contractile properties (twitch characteristics, force-frequency relationships, maximal force) among the three groups. Our fatigue protocol (30 Hz, 0.25 duty cycle, 37 degrees C) depressed force to 25% of the initial force; however, lack of RyR3 did not accelerate the decline in force production. The force-frequency relationship was shifted to higher frequencies and was depressed in fatigued diaphragm; lack of RyR3 did not exaggerate these changes. We therefore provide evidence that RyR3 deficiency does not alter contractile function of adult muscle before, during, or after fatigue.

  2. Increased acetyl group availability enhances contractile function of canine skeletal muscle during ischemia.

    PubMed

    Timmons, J A; Poucher, S M; Constantin-Teodosiu, D; Worrall, V; Macdonald, I A; Greenhaff, P L

    1996-02-01

    Skeletal muscle contractile function is impaired during acute ischemia such as that experienced by peripheral vascular disease patients. We therefore, examined the effects of dichloroacetate, which can alter resting metabolism, on canine gracilis muscle contractile function during constant flow ischemia. Pretreatment with dichloroacetate increased resting pyruvate dehydrogenase complex activity and resting acetylcarnitine concentration by approximately 4- and approximately 10-fold, respectively. After 20-min contraction the control group had demonstrated an approximately 40% reduction in isomeric tension whereas the dichloroacetate group had fatigued by approximately 25% (P < 0.05). Dichloroacetate resulted in less lactate accumulation (10.3 +/- 3.0 vs 58.9 +/- 10.5 mmol.kg-1 dry muscle [dm], P < 0.05) and phosphocreatine hydrolysis (15.6 +/- 6.3 vs 33.8 +/- 9.0 mmol.kg-1 dm, P < 0.05) during contraction. Acetylcarnitine concentration fell during contraction by 5.4 +/- 1.8 mmol.kg-1 dm in the dichloroacetate group but increased by 10.0 +/- 1.9 mmol.kg-1 dm in the control group. In conclusion, dichloroacetate enhanced contractile function during ischemia, independently of blood flow, such that it appears oxidative ATP regeneration is limited by pyruvate dehydrogenase complex activity and acetyl group availability. PMID:8609248

  3. Electrophysiological and contractile function of cardiomyocytes derived from human embryonic stem cells

    PubMed Central

    Blazeski, Adriana; Zhu, Renjun; Hunter, David W.; Weinberg, Seth H.; Boheler, Kenneth R.; Zambidis, Elias T.; Tung, Leslie

    2013-01-01

    Human embryonic stem cells have emerged as the prototypical source from which cardiomyocytes can be derived for use in drug discovery and cell therapy. However, such applications require that these cardiomyocytes (hESC-CMs) faithfully recapitulate the physiology of adult cells, especially in relation to their electrophysiological and contractile function. We review what is known about the electrophysiology of hESC-CMs in terms of beating rate, action potential characteristics, ionic currents, and cellular coupling as well as their contractility in terms of calcium cycling and contraction. We also discuss the heterogeneity in cellular phenotypes that arises from variability in cardiac differentiation, maturation, and culture conditions, and summarize present strategies that have been implemented to reduce this heterogeneity. Finally, we present original electrophysiological data from optical maps of hESC-CM clusters. PMID:22958937

  4. Canonical transient receptor potential 1 channel is involved in contractile function of glomerular mesangial cells.

    PubMed

    Du, Juan; Sours-Brothers, Sherry; Coleman, Rashadd; Ding, Min; Graham, Sarabeth; Kong, De-Hu; Ma, Rong

    2007-05-01

    Contractility of mesangial cells (MC) is tightly controlled by [Ca(2+)](i). Ca(2+) influx across the plasma membrane constitutes a major component of mesangial responses to vasoconstrictors. Canonical transient receptor potential 1 (TRPC1) is a Ca(2+)-permeable cation channel in a variety of cell types. This study was performed to investigate whether TRPC1 takes part in vasoconstrictor-induced mesangial contraction by mediating Ca(2+) entry. It was found that angiotensin II (AngII) evoked remarkable contraction of the cultured MC. Downregulation of TRPC1 using RNA interference significantly attenuated the contractile response. Infusion of AngII or endothelin-1 in rats caused a decrease in GFR. The GFR decline was significantly reduced by infusion of TRPC1 antibody that targets an extracellular domain in the pore region of TRPC1 channel. However, the treatment of TRPC1 antibody did not affect the AngII-induced vasopressing effect. Electrophysiologic experiments revealed that functional or biologic inhibition of TRPC1 significantly depressed AngII-induced channel activation. Fura-2 fluorescence-indicated that Ca(2+) entry in response to AngII stimulation was also dramatically inhibited by TRPC1 antibody and TRPC1-specific RNA interference. These results suggest that TRPC1 plays an important role in controlling contractile function of MC. Mediation of Ca(2+) entry might be the underlying mechanism for the TRPC1-associated MC contraction. PMID:17389736

  5. Functional Overloading of Dystrophic Mice Enhances Muscle-Derived Stem Cell Contribution to Muscle Contractile Capacity

    PubMed Central

    Ambrosio, Fabrisia; Ferrari, Ricardo J.; Fitzgerald, G. Kelley; Carvell, George; Boninger, Michael L.; Huard, Johnny

    2016-01-01

    Objectives To evaluate the effect of functional overloading on the transplantation of muscle derived stem cells (MDSCs) into dystrophic muscle and the ability of transplanted cells to increase dystrophic muscle’s ability to resist overloading-induced weakness. Design Cross-sectional. Setting Laboratory. Animals Male mice (N=10) with a dystrophin gene mutation. Interventions MDSCs were intramuscularly transplanted into the extensor digitorum longus muscle (EDL). Functional overloading of the EDL was performed by surgical ablation of the EDL’s synergist. Main Outcome Measures The total number of dystrophin-positive fibers/cross-section (as a measure of stem cell engraftment), the average number of CD31+ cells (as a measure of capillarity), and in vitro EDL contractile strength. Independent t tests were used to investigate the effect of overloading on engraftment, capillarity, and strength. Paired t tests were used to investigate the effect of MDSC engraftment on strength and capillarity. Results MDSC transplantation protects dystrophic muscles against overloading-induced weakness (specific twitch force: control 4.5N/cm2±2.3; MDSC treated 7.9N/cm2±1.4) (P=.02). This improved force production following overloading is concomitant with an increased regeneration by transplanted MDSCs (MDSC: 26.6±20.2 dystrophin-positive fibers/cross-section; overloading + MDSC: 170.6±130.9 dystrophin-positive fibers/cross-section [P=.03]). Overloading-induced increases in skeletal muscle capillarity is significantly correlated with increased MDSC engraftment (R2=.80, P=.01). Conclusions These findings suggest that the functional contribution of transplanted MDSCs may rely on activity-dependent mechanisms, possibly mediated by skeletal muscle vascularity. Rehabilitation modalities may play an important role in the development of stem cell transplantation strategies for the treatment of muscular dystrophy. PMID:19154831

  6. A single resistance exercise session improves myocardial contractility in spontaneously hypertensive rats.

    PubMed

    Fernandes, A A; Faria, T de O; Ribeiro Júnior, R F; Costa, G P; Marchezini, B; Silveira, E A; Angeli, J K; Stefanon, I; Vassallo, D V; Lizardo, J H

    2015-09-01

    Resistance training evokes myocardial adaptation; however, the effects of a single resistance exercise session on cardiac performance are poorly understood or investigated. This study aimed to investigate the effects of a single resistance exercise session on the myocardial contractility of spontaneously hypertensive rats (SHRs). Male 3-month-old SHRs were divided into two groups: control (Ct) and exercise (Ex). Control animals were submitted to sham exercise. Blood pressure was measured in conscious rats before the exercise session to confirm the presence of arterial hypertension. Ten minutes after the exercise session, the animals were anesthetized and killed, and the hearts were removed. Cardiac contractility was evaluated in the whole heart by the Langendorff technique and by isometric contractions of isolated left ventricular papillary muscles. SERCA2a, phospholamban (PLB), and phosphorylated PLB expression were investigated by Western blot. Exercise increased force development of isolated papillary muscles (Ex=1.0±0.1 g/mg vs Ct=0.63±0.2 g/mg, P<0.05). Post-rest contraction was greater in the exercised animals (Ex=4.1±0.4% vs Ct=1.7±0.2%, P<0.05). Papillary muscles of exercised animals developed greater force under increasing isoproterenol concentrations (P<0.05). In the isolated heart, exercise increased left ventricular isovolumetric systolic pressure (LVISP; Δ +39 mmHg; P<0.05) from baseline conditions. Hearts from the exercised rats presented a greater response to increasing diastolic pressure. Positive inotropic intervention to calcium and isoproterenol resulted in greater LVISP in exercised animals (P<0.05). The results demonstrated that a single resistance exercise session improved myocardial contractility in SHRs. PMID:26176315

  7. A single resistance exercise session improves myocardial contractility in spontaneously hypertensive rats

    PubMed Central

    Fernandes, A.A.; Faria, T. de O.; Ribeiro, R.F.; Costa, G.P.; Marchezini, B.; Silveira, E.A.; Angeli, J.K.; Stefanon, I.; Vassallo, D.V.; Lizardo, J.H.

    2015-01-01

    Resistance training evokes myocardial adaptation; however, the effects of a single resistance exercise session on cardiac performance are poorly understood or investigated. This study aimed to investigate the effects of a single resistance exercise session on the myocardial contractility of spontaneously hypertensive rats (SHRs). Male 3-month-old SHRs were divided into two groups: control (Ct) and exercise (Ex). Control animals were submitted to sham exercise. Blood pressure was measured in conscious rats before the exercise session to confirm the presence of arterial hypertension. Ten minutes after the exercise session, the animals were anesthetized and killed, and the hearts were removed. Cardiac contractility was evaluated in the whole heart by the Langendorff technique and by isometric contractions of isolated left ventricular papillary muscles. SERCA2a, phospholamban (PLB), and phosphorylated PLB expression were investigated by Western blot. Exercise increased force development of isolated papillary muscles (Ex=1.0±0.1 g/mg vs Ct=0.63±0.2 g/mg, P<0.05). Post-rest contraction was greater in the exercised animals (Ex=4.1±0.4% vs Ct=1.7±0.2%, P<0.05). Papillary muscles of exercised animals developed greater force under increasing isoproterenol concentrations (P<0.05). In the isolated heart, exercise increased left ventricular isovolumetric systolic pressure (LVISP; Δ +39 mmHg; P<0.05) from baseline conditions. Hearts from the exercised rats presented a greater response to increasing diastolic pressure. Positive inotropic intervention to calcium and isoproterenol resulted in greater LVISP in exercised animals (P<0.05). The results demonstrated that a single resistance exercise session improved myocardial contractility in SHRs. PMID:26176315

  8. Chronic disuse and skeletal muscle structure in older adults: sex-specific differences and relationships to contractile function

    PubMed Central

    Callahan, Damien M.; Tourville, Timothy W.; Miller, Mark S.; Hackett, Sarah B.; Sharma, Himani; Cruickshank, Nicholas C.; Slauterbeck, James R.; Savage, Patrick D.; Ades, Philip A.; Maughan, David W.; Beynnon, Bruce D.

    2015-01-01

    In older adults, we examined the effect of chronic muscle disuse on skeletal muscle structure at the tissue, cellular, organellar, and molecular levels and its relationship to muscle function. Volunteers with advanced-stage knee osteoarthritis (OA, n = 16) were recruited to reflect the effects of chronic lower extremity muscle disuse and compared with recreationally active controls (n = 15) without knee OA but similar in age, sex, and health status. In the OA group, quadriceps muscle and single-fiber cross-sectional area were reduced, with the largest reduction in myosin heavy chain IIA fibers. Myosin heavy chain IIAX fibers were more prevalent in the OA group, and their atrophy was sex-specific: men showed a reduction in cross-sectional area, and women showed no differences. Myofibrillar ultrastructure, myonuclear content, and mitochondrial content and morphology generally did not differ between groups, with the exception of sex-specific adaptations in subsarcolemmal (SS) mitochondria, which were driven by lower values in OA women. SS mitochondrial content was also differently related to cellular and molecular functional parameters by sex: greater SS mitochondrial content was associated with improved contractility in women but reduced function in men. Collectively, these results demonstrate sex-specific structural phenotypes at the cellular and organellar levels with chronic disuse in older adults, with novel associations between energetic and contractile systems. PMID:25810256

  9. Myocardial Mitochondrial and Contractile Function Are Preserved in Mice Lacking Adiponectin

    PubMed Central

    Braun, Martin; Hettinger, Niko; Koentges, Christoph; Pfeil, Katharina; Cimolai, Maria C.; Hoffmann, Michael M.; Osterholt, Moritz; Doenst, Torsten; Bode, Christoph; Bugger, Heiko

    2015-01-01

    Adiponectin deficiency leads to increased myocardial infarct size following ischemia reperfusion and to exaggerated cardiac hypertrophy following pressure overload, entities that are causally linked to mitochondrial dysfunction. In skeletal muscle, lack of adiponectin results in impaired mitochondrial function. Thus, it was our objective to investigate whether adiponectin deficiency impairs mitochondrial energetics in the heart. At 8 weeks of age, heart weight-to-body weight ratios were not different between adiponectin knockout (ADQ-/-) mice and wildtypes (WT). In isolated working hearts, cardiac output, aortic developed pressure and cardiac power were preserved in ADQ-/- mice. Rates of fatty acid oxidation, glucose oxidation and glycolysis were unchanged between groups. While myocardial oxygen consumption was slightly reduced (-24%) in ADQ-/- mice in isolated working hearts, rates of maximal ADP-stimulated mitochondrial oxygen consumption and ATP synthesis in saponin-permeabilized cardiac fibers were preserved in ADQ-/- mice with glutamate, pyruvate or palmitoyl-carnitine as a substrate. In addition, enzymatic activity of respiratory complexes I and II was unchanged between groups. Phosphorylation of AMP-activated protein kinase and SIRT1 activity were not decreased, expression and acetylation of PGC-1α were unchanged, and mitochondrial content of OXPHOS subunits was not decreased in ADQ-/- mice. Finally, increasing energy demands due to prolonged subcutaneous infusion of isoproterenol did not differentially affect cardiac contractility or mitochondrial function in ADQ-/- mice compared to WT. Thus, mitochondrial and contractile function are preserved in hearts of mice lacking adiponectin, suggesting that adiponectin may be expendable in the regulation of mitochondrial energetics and contractile function in the heart under non-pathological conditions. PMID:25785965

  10. Intracoronary infusion of autologous mononuclear cells from bone marrow or G-CSF mobilised apheresis product may not improve remodelling, contractile function, perfusion or infarct size in a swine model of large myocardial infarction

    PubMed Central

    de Silva, Ranil; Raval, Amish N.; Hadi, Mohiuddin; Gildea, Karena M.; Bonifacino, Aylin C.; Yu, Zu-Xi; Yau, Yu Ying; Leitman, Susan F.; Bacharach, Stephen L.; Donahue, Robert E.; Read, Elizabeth J.; Lederman, Robert J.

    2008-01-01

    Background In a blinded, placebo controlled study, we investigated whether intracoronary infusion of autologous mononuclear cells from G-CSF mobilised apheresis product or bone marrow (BM) improved sensitive outcome measures in a swine model of large MI. Methods and Results Four days after LAD occlusion and reperfusion, cells from BM or apheresis product of saline (Placebo) or G-CSF injected animals were infused into the LAD. Large infarcts were created: baseline ejection fraction (EF) by MRI of 35.3 ± 8.5%, no difference between the Placebo, G-CSF and BM groups (p=0.16 by ANOVA). At 6 weeks EF fell to a similar degree in the Placebo, G-CSF and BM groups (−7.9±6.0%, −8.5±8.8% and −10.9±7.6%, p=0.78 by ANOVA). Left ventricular volumes and infarct size by MRI deteriorated similarly in all 3 groups. Quantitative PET demonstrated significant decline in FDG uptake rate in the LAD territory at follow-up, with no histological, angiographic or PET perfusion evidence of functional neovascularisation. Immunofluorescence failed to demonstrate transdifferentiation of infused cells. Conclusion Intracoronary infusion of mononuclear cells from either bone marrow or G-CSF mobilised apheresis product may not improve or limit deterioration in systolic function, adverse ventricular remodelling, infarct size or perfusion in a swine model of large MI. PMID:18502738

  11. Different Anti-Contractile Function and Nitric Oxide Production of Thoracic and Abdominal Perivascular Adipose Tissues

    PubMed Central

    Victorio, Jamaira A.; Fontes, Milene T.; Rossoni, Luciana V.; Davel, Ana P.

    2016-01-01

    Divergent phenotypes between the perivascular adipose tissue (PVAT) surrounding the abdominal and the thoracic aorta might be implicated in regional aortic differences, such as susceptibility to atherosclerosis. Although PVAT of the thoracic aorta exhibits anti-contractile function, the role of PVAT in the regulation of the vascular tone of the abdominal aorta is not well defined. In the present study, we compared the anti-contractile function, nitric oxide (NO) availability, and reactive oxygen species (ROS) formation in PVAT and vessel walls of abdominal and thoracic aorta. Abdominal and thoracic aortic tissue from male Wistar rats were used to perform functional and molecular experiments. PVAT reduced the contraction evoked by phenylephrine in the absence and presence of endothelium in the thoracic aorta, whereas this anti-contractile effect was not observed in the abdominal aorta. Abdominal PVAT exhibited a reduction in endothelial NO synthase (eNOS) expression compared with thoracic PVAT, without differences in eNOS expression in the vessel walls. In agreement with this result, NO production evaluated in situ using 4,5-diaminofluorescein was less pronounced in abdominal compared with thoracic aortic PVAT, whereas no significant difference was observed for endothelial NO production. Moreover, NOS inhibition with L-NAME enhanced the phenylephrine-induced contraction in endothelial-denuded rings with PVAT from thoracic but not abdominal aorta. ROS formation and lipid peroxidation products evaluated through the quantification of hydroethidine fluorescence and 4-hydroxynonenal adducts, respectively, were similar between PVAT and vessel walls from the abdominal and thoracic aorta. Extracellular superoxide dismutase (SOD) expression was similar between the vessel walls and PVAT of the abdominal and thoracic aorta. However, Mn-SOD levels were reduced, while CuZn-SOD levels were increased in abdominal PVAT compared with thoracic aortic PVAT. In conclusion, our results

  12. Assessment of lymphatic contractile function following manual lymphatic drainage using near-infrared fluorescence imaging

    PubMed Central

    Tan, I-Chih; Maus, Erik A.; Rasmussen, John C.; Marshall, Milton V.; Adams, Kristen E.; Fife, Caroline E.; Smith, Latisha A.; Chan, Wenyaw; Sevick-Muraca, Eva M.

    2011-01-01

    Objective To investigate the feasibility of assessing the efficacy of manual lymphatic drainage (MLD), a method for lymphedema (LE) management, using near-infrared (NIR) fluorescence imaging. Design Exploratory pilot study. Setting Primary care unit. Intervention Indocyanine green of 25 μg in 0.1 cc each was injected intradermally in bilateral arms or legs of subjects. Diffused excitation light illuminated the limbs and NIR fluorescence images were collected using custom-built imaging systems. The subjects received MLD therapy, and imaging was performed pre- and post- therapy. Participants Ten subjects (age 18 – 68) diagnosed with Grade I or II LE and 12 normal control subjects (age 22 – 59). Main outcome measures Apparent lymph velocities and the periods between lymphatic propulsion events were computed from fluorescence images. The data collected pre- and post- MLD were compared and evaluated for differences. Results By comparing the pre- MLD lymphatic contractile function against post- MLD lymphatic function, our results show that the average apparent lymph velocity increased in both the symptomatic (+23%) and asymptomatic (+25%) limbs of LE subjects and in the control limbs (+28%) of normal subjects. The average lymphatic propulsion period decreased in the symptomatic (−9%) and asymptomatic (−20%) limbs of LE subjects, as well as in the control limbs (−23%). Conclusions We demonstrated that NIR fluorescence imaging could be used to quantify immediate benefits of lymphatic contractile function following MLD. PMID:21530723

  13. A functional connection of Dictyostelium paracaspase with the contractile vacuole and a possible partner of the vacuolar proton ATPase.

    PubMed

    Saheb, Entsar; Biton, Ithay; Maringer, Katherine; Bush, John

    2013-09-01

    Dictyostelium discoideum possesses only one caspase family member, paracaspase (pcp). Two separate mutant cell lines were first analysed: one cell line was an over-expressed GFP-tagged Pcp (GFP-Pcp), while the other cell line was a pcp-null (pcp-). Microscopic analysis of cells expressing GFP-Pcp revealed that Pcp was associated with the contractile vacuole membrane consisting of bladder-like vacuoles. This association was disrupted when cells were exposed to osmotic stress conditions. Compared with wild-type cells, the GFP-Pcp-over-expressing cells were susceptible to osmotic stress and were seen to be very rounded in hypo-osmotic conditions and contained more abnormally swollen contractile vacuole. Cells with pcp- were also rounded but had few, if any, contractile vacuoles. These observations suggest that Pcp is essential for Dictyostelium osmotic regulation via its functioning in the contractile vacuole system. Subjecting these cells to selected contractile vacuole inhibitor provided additional support for these findings. Furthermore, yeast two-hybrid system identified vacuolar proton ATPase (VatM) as the protein interacting with Pcp. Taken together, this work gives evidence for an eukaryotic paracaspase to be associated with both localization in and regulation of the contractile vacuolar system, an organelle critical for maintaining the normal morphology of the cell. PMID:23938384

  14. Evolutionarily conserved sites in yeast tropomyosin function in cell polarity, transport and contractile ring formation

    PubMed Central

    Cranz-Mileva, Susanne; MacTaggart, Brittany; Russell, Jacquelyn; Hitchcock-DeGregori, Sarah E.

    2015-01-01

    ABSTRACT Tropomyosin is a coiled-coil protein that binds and regulates actin filaments. The tropomyosin gene in Schizosaccharomyces pombe, cdc8, is required for formation of actin cables, contractile rings, and polar localization of actin patches. The roles of conserved residues were investigated in gene replacement mutants. The work validates an evolution-based approach to identify tropomyosin functions in living cells and sites of potential interactions with other proteins. A cdc8 mutant with near-normal actin affinity affects patch polarization and vacuole fusion, possibly by affecting Myo52p, a class V myosin, function. The presence of labile residual cell attachments suggests a delay in completion of cell division and redistribution of cell patches following cytokinesis. Another mutant with a mild phenotype is synthetic negative with GFP-fimbrin, inferring involvement of the mutated tropomyosin sites in interaction between the two proteins. Proteins that assemble in the contractile ring region before actin do so in a mutant cdc8 strain that cannot assemble condensed actin rings, yet some cells can divide. Of general significance, LifeAct-GFP negatively affects the actin cytoskeleton, indicating caution in its use as a biomarker for actin filaments. PMID:26187949

  15. Functional insights into modulation of BKCa channel activity to alter myometrial contractility

    PubMed Central

    Lorca, Ramón A.; Prabagaran, Monali; England, Sarah K.

    2014-01-01

    The large-conductance voltage- and Ca2+-activated K+ channel (BKCa) is an important regulator of membrane excitability in a wide variety of cells and tissues. In myometrial smooth muscle, activation of BKCa plays essential roles in buffering contractility to maintain uterine quiescence during pregnancy and in the transition to a more contractile state at the onset of labor. Multiple mechanisms of modulation have been described to alter BKCa channel activity, expression, and cellular localization. In the myometrium, BKCa is regulated by alternative splicing, protein targeting to the plasma membrane, compartmentation in membrane microdomains, and posttranslational modifications. In addition, interaction with auxiliary proteins (i.e., β1- and β2-subunits), association with G-protein coupled receptor signaling pathways, such as those activated by adrenergic and oxytocin receptors, and hormonal regulation provide further mechanisms of variable modulation of BKCa channel function in myometrial smooth muscle. Here, we provide an overview of these mechanisms of BKCa channel modulation and provide a context for them in relation to myometrial function. PMID:25132821

  16. Cardiac Non-myocyte Cells Show Enhanced Pharmacological Function Suggestive of Contractile Maturity in Stem Cell Derived Cardiomyocyte Microtissues.

    PubMed

    Ravenscroft, Stephanie M; Pointon, Amy; Williams, Awel W; Cross, Michael J; Sidaway, James E

    2016-07-01

    The immature phenotype of stem cell derived cardiomyocytes is a significant barrier to their use in translational medicine and pre-clinical in vitro drug toxicity and pharmacological analysis. Here we have assessed the contribution of non-myocyte cells on the contractile function of co-cultured human embryonic stem cell derived cardiomyocytes (hESC-CMs) in spheroid microtissue format. Microtissues were formed using a scaffold free 96-well cell suspension method from hESC-CM cultured alone (CM microtissues) or in combination with human primary cardiac microvascular endothelial cells and cardiac fibroblasts (CMEF microtissues). Contractility was characterized with fluorescence and video-based edge detection. CMEF microtissues displayed greater Ca(2+ )transient amplitudes, enhanced spontaneous contraction rate and remarkably enhanced contractile function in response to both positive and negative inotropic drugs, suggesting a more mature contractile phenotype than CM microtissues. In addition, for several drugs the enhanced contractile response was not apparent when endothelial cell or fibroblasts from a non-cardiac tissue were used as the ancillary cells. Further evidence of maturity for CMEF microtissues was shown with increased expression of genes that encode proteins critical in cardiac Ca(2+ )handling (S100A1), sarcomere assembly (telethonin/TCAP) and β-adrenergic receptor signalling. Our data shows that compared with single cell-type cardiomyocyte in vitro models, CMEF microtissues are superior at predicting the inotropic effects of drugs, demonstrating the critical contribution of cardiac non-myocyte cells in mediating functional cardiotoxicity. PMID:27125969

  17. Cardiac Non-myocyte Cells Show Enhanced Pharmacological Function Suggestive of Contractile Maturity in Stem Cell Derived Cardiomyocyte Microtissues

    PubMed Central

    Ravenscroft, Stephanie M.; Pointon, Amy; Williams, Awel W.; Cross, Michael J.; Sidaway, James E.

    2016-01-01

    The immature phenotype of stem cell derived cardiomyocytes is a significant barrier to their use in translational medicine and pre-clinical in vitro drug toxicity and pharmacological analysis. Here we have assessed the contribution of non-myocyte cells on the contractile function of co-cultured human embryonic stem cell derived cardiomyocytes (hESC-CMs) in spheroid microtissue format. Microtissues were formed using a scaffold free 96-well cell suspension method from hESC-CM cultured alone (CM microtissues) or in combination with human primary cardiac microvascular endothelial cells and cardiac fibroblasts (CMEF microtissues). Contractility was characterized with fluorescence and video-based edge detection. CMEF microtissues displayed greater Ca2+ transient amplitudes, enhanced spontaneous contraction rate and remarkably enhanced contractile function in response to both positive and negative inotropic drugs, suggesting a more mature contractile phenotype than CM microtissues. In addition, for several drugs the enhanced contractile response was not apparent when endothelial cell or fibroblasts from a non-cardiac tissue were used as the ancillary cells. Further evidence of maturity for CMEF microtissues was shown with increased expression of genes that encode proteins critical in cardiac Ca2+ handling (S100A1), sarcomere assembly (telethonin/TCAP) and β-adrenergic receptor signalling. Our data shows that compared with single cell-type cardiomyocyte in vitro models, CMEF microtissues are superior at predicting the inotropic effects of drugs, demonstrating the critical contribution of cardiac non-myocyte cells in mediating functional cardiotoxicity. PMID:27125969

  18. [Peculiarities of cardiac contractile function in patients with arterial hypertension depending on temperament and anxiety state].

    PubMed

    2011-01-01

    The aim of the work was to elucidate the relationship between temperament and personal anxiety and between left ventricular myocardium hypertrophy, contractility and diastolic function in 671 men (mean age 54 +/- 1.8 yr) with newly diagnosed grade II arterial hypertension who took no antihypertensive drugs before the study. The tone of vegetative nervous system, serum levels of cortisol, aldosterone, thyroxin, and insulin were measured. EchoCG was used to determine left ventricular myocardium mass (LVMM), LVMM index, the ratio of transmitral blood flow at the beginning and end of diastole, left ventricular ejection and shortening fractions, end-systolic and diastolic size and volume. Phlegmatic and melancholic patients differed from cholerics and sanguinics in the predominance of parasympathetic influences, elevated blood aldosterone and insulin levels in combination with higher LVMM and LVMM index but lower left ventricular systolic and diastolic function. These characteristics were especially well apparent in anxious subjects comprising a risk group for cardiac insufficiency. PMID:22420192

  19. Exposure to low mercury concentration in vivo impairs myocardial contractile function

    SciTech Connect

    Furieri, Lorena Barros; Fioresi, Mirian; Junior, Rogerio Faustino Ribeiro; Bartolome, Maria Visitacion; Fernandes, Aurelia Araujo; Cachofeiro, Victoria; Lahera, Vicente; Salaices, Mercedes; Stefanon, Ivanita; Vassallo, Dalton Valentim

    2011-09-01

    Increased cardiovascular risk after mercury exposure has been described but cardiac effects resulting from controlled chronic treatment are not yet well explored. We analyzed the effects of chronic exposure to low mercury concentrations on hemodynamic and ventricular function of isolated hearts. Wistar rats were treated with HgCl{sub 2} (1st dose 4.6 {mu}g/kg, subsequent dose 0.07 {mu}g/kg/day, im, 30 days) or vehicle. Mercury treatment did not affect blood pressure (BP) nor produced cardiac hypertrophy or changes of myocyte morphometry and collagen content. This treatment: 1) in vivo increased left ventricle end diastolic pressure (LVEDP) without changing left ventricular systolic pressure (LVSP) and heart rate; 2) in isolated hearts reduced LV isovolumic systolic pressure and time derivatives, and {beta}-adrenergic response; 3) increased myosin ATPase activity; 4) reduced Na{sup +}-K{sup +} ATPase (NKA) activity; 5) reduced protein expression of SERCA and phosphorylated phospholamban on serine 16 while phospholamban expression increased; as a consequence SERCA/phospholamban ratio reduced; 6) reduced sodium/calcium exchanger (NCX) protein expression and {alpha}-1 isoform of NKA, whereas {alpha}-2 isoform of NKA did not change. Chronic exposure for 30 days to low concentrations of mercury does not change BP, heart rate or LVSP but produces small but significant increase of LVEDP. However, in isolated hearts mercury treatment promoted contractility dysfunction as a result of the decreased NKA activity, reduction of NCX and SERCA and increased PLB protein expression. These findings offer further evidence that mercury chronic exposure, even at small concentrations, is an environmental risk factor affecting heart function. - Highlights: > Unchanges blood pressure, heart rate, systolic pressure. > Increases end diastolic pressure. > Promotes cardiac contractility dysfunction. > Decreases NKA activity, NCX and SERCA, increases PLB protein expression. > Small

  20. Genomic modulation of mitochondrial respiratory genes in the hypertrophied heart reflects adaptive changes in mitochondrial and contractile function

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We hypothesized the coordinate induction of mitochondrial regulatory genes in the hypertrophied right ventricle to sustain mitochondrial respiratory capacity and contractile function in response to increased load. Wistar rats were exposed to hypobaric hypoxia (11% O(2)) or normoxia for 2 wk. Cardiac...

  1. Microtubule depolymerization normalizes in vivo myocardial contractile function in dogs with pressure-overload left ventricular hypertrophy

    NASA Technical Reports Server (NTRS)

    Koide, M.; Hamawaki, M.; Narishige, T.; Sato, H.; Nemoto, S.; DeFreyte, G.; Zile, M. R.; Cooper G, I. V.; Carabello, B. A.

    2000-01-01

    BACKGROUND: Because initially compensatory myocardial hypertrophy in response to pressure overloading may eventually decompensate to myocardial failure, mechanisms responsible for this transition have long been sought. One such mechanism established in vitro is densification of the cellular microtubule network, which imposes a viscous load that inhibits cardiocyte contraction. METHODS AND RESULTS: In the present study, we extended this in vitro finding to the in vivo level and tested the hypothesis that this cytoskeletal abnormality is important in the in vivo contractile dysfunction that occurs in experimental aortic stenosis in the adult dog. In 8 dogs in which gradual stenosis of the ascending aorta had caused severe left ventricular (LV) pressure overloading (gradient, 152+/-16 mm Hg) with contractile dysfunction, LV function was measured at baseline and 1 hour after the intravenous administration of colchicine. Cardiocytes obtained by biopsy before and after in vivo colchicine administration were examined in tandem. Microtubule depolymerization restored LV contractile function both in vivo and in vitro. CONCLUSIONS: These and additional corroborative data show that increased cardiocyte microtubule network density is an important mechanism for the ventricular contractile dysfunction that develops in large mammals with adult-onset pressure-overload-induced cardiac hypertrophy.

  2. Nebulin-deficient mice exhibit shorter thin filament lengths and reduced contractile function in skeletal muscle

    PubMed Central

    Bang, Marie-Louise; Li, Xiaodong; Littlefield, Ryan; Bremner, Shannon; Thor, Andrea; Knowlton, Kirk U.; Lieber, Richard L.; Chen, Ju

    2006-01-01

    Nebulin is a giant modular sarcomeric protein that has been proposed to play critical roles in myofibrillogenesis, thin filament length regulation, and muscle contraction. To investigate the functional role of nebulin in vivo, we generated nebulin-deficient mice by using a Cre knock-in strategy. Lineage studies utilizing this mouse model demonstrated that nebulin is expressed uniformly in all skeletal muscles. Nebulin-deficient mice die within 8–11 d after birth, with symptoms including decreased milk intake and muscle weakness. Although myofibrillogenesis had occurred, skeletal muscle thin filament lengths were up to 25% shorter compared with wild type, and thin filaments were uniform in length both within and between muscle types. Ultrastructural studies also demonstrated a critical role for nebulin in the maintenance of sarcomeric structure in skeletal muscle. The functional importance of nebulin in skeletal muscle function was revealed by isometric contractility assays, which demonstrated a dramatic reduction in force production in nebulin-deficient skeletal muscle. PMID:16769824

  3. Constitutively active phosphatase inhibitor-1 improves cardiac contractility in young mice but is deleterious after catecholaminergic stress and with aging

    PubMed Central

    Wittköpper, Katrin; Fabritz, Larissa; Neef, Stefan; Ort, Katharina R.; Grefe, Clemens; Unsöld, Bernhard; Kirchhof, Paulus; Maier, Lars S.; Hasenfuss, Gerd; Dobrev, Dobromir; Eschenhagen, Thomas; El-Armouche, Ali

    2010-01-01

    Phosphatase inhibitor-1 (I-1) is a distal amplifier element of β-adrenergic signaling that functions by preventing dephosphorylation of downstream targets. I-1 is downregulated in human failing hearts, while overexpression of a constitutively active mutant form (I-1c) reverses contractile dysfunction in mouse failing hearts, suggesting that I-1c may be a candidate for gene therapy. We generated mice with conditional cardiomyocyte-restricted expression of I-1c (referred to herein as dTGI-1c mice) on an I-1–deficient background. Young adult dTGI-1c mice exhibited enhanced cardiac contractility but exaggerated contractile dysfunction and ventricular dilation upon catecholamine infusion. Telemetric ECG recordings revealed typical catecholamine-induced ventricular tachycardia and sudden death. Doxycycline feeding switched off expression of cardiomyocyte-restricted I-1c and reversed all abnormalities. Hearts from dTGI-1c mice showed hyperphosphorylation of phospholamban and the ryanodine receptor, and this was associated with an increased number of catecholamine-induced Ca2+ sparks in isolated myocytes. Aged dTGI-1c mice spontaneously developed a cardiomyopathic phenotype. These data were confirmed in a second independent transgenic mouse line, expressing a full-length I-1 mutant that could not be phosphorylated and thereby inactivated by PKC-α (I-1S67A). In conclusion, conditional expression of I-1c or I-1S67A enhanced steady-state phosphorylation of 2 key Ca2+-regulating sarcoplasmic reticulum enzymes. This was associated with increased contractile function in young animals but also with arrhythmias and cardiomyopathy after adrenergic stress and with aging. These data should be considered in the development of novel therapies for heart failure. PMID:20071777

  4. Molecular and functional analyses of the contractile apparatus in lymphatic muscle

    NASA Technical Reports Server (NTRS)

    Muthuchamy, Mariappan; Gashev, Anatoliy; Boswell, Niven; Dawson, Nancy; Zawieja, David; Delp, Z. (Principal Investigator)

    2003-01-01

    Lymphatics are necessary for the generation and regulation of lymph flow. Lymphatics use phasic contractions and extrinsic compressions to generate flow; tonic contractions alter resistance. Lymphatic muscle exhibits important differences from typical vascular smooth muscle. In this study, the thoracic duct exhibited significant functional differences from mesenteric lymphatics. To understand the molecular basis for these differences, we examined the profiles of contractile proteins and their messages in mesenteric lymphatics, thoracic duct, and arterioles. Results demonstrated that mesenteric lymphatics express only SMB smooth muscle myosin heavy chain (SM-MHC), whereas thoracic duct and arterioles expressed both SMA and SMB isoforms. Both SM1 and SM2 isoforms of SM-MHC were detected in arterioles and mesenteric and thoracic lymphatics. In addition, the fetal cardiac/skeletal slow-twitch muscle-specific beta-MHC message was detected only in mesenteric lymphatics. All four actin messages, cardiac alpha-actin, vascular alpha-actin, enteric gamma-actin, and skeletal alpha-actin, were present in both mesenteric lymphatics and arterioles. However, in thoracic duct, predominantly cardiac alpha-actin and vascular alpha-actin were found. Western blot and immunohistochemical analyses corroborated the mRNA studies. However, in arterioles only vascular alpha-actin protein was detected. These data indicate that lymphatics display genotypic and phenotypic characteristics of vascular, cardiac, and visceral myocytes, which are needed to fulfill the unique roles of the lymphatic system.

  5. Metabolic responses from rest to steady state determine contractile function in ischemic skeletal muscle.

    PubMed

    Timmons, J A; Poucher, S M; Constantin-Teodosiu, D; Macdonald, I A; Greenhaff, P L

    1997-08-01

    Skeletal muscle contraction during ischemia, such as that experienced by peripheral vascular disease patients, is characterized by rapid fatigue. Using a canine gracilis model, we tested the hypothesis that a critical factor determining force production during ischemia is the metabolic response during the transition from rest to steady state. Dichloroacetate (DCA) administration before gracilis muscle contraction increased pyruvate dehydrogenase complex activation and resulted in acetylation of 80% of the free carnitine pool to acetylcarnitine. After 1 min of contraction, phosphocreatine (PCr) degradation in the DCA group was approximately 50% lower than in the control group (P < 0.05) during conditions of identical force production. After 6 min of contraction, steady-state force production was approximately 30% higher in the DCA group (P < 0.05), and muscle ATP, PCr, and glycogen degradation and lactate accumulation were lower (P < 0.05 in all cases). It appears, therefore, that an important determinant of contractile function during ischemia is the mechanisms by which ATP regeneration occurs during the period of rest to steady-state transition. PMID:9277374

  6. The contractile vacuole complex of protists--new cues to function and biogenesis.

    PubMed

    Plattner, Helmut

    2015-06-01

    The contractile vacuole complex (CVC) of freshwater protists sequesters the excess of water and ions (Ca(2+)) for exocytosis cycles at the pore. Sequestration is based on a chemiosmotic proton gradient produced by a V-type H(+)-ATPase. So far, many pieces of information available have not been combined to a comprehensive view on CVC biogenesis and function. One main function now appears as follows. Ca(2+)-release channels, type inositol 1,4,5-trisphosphate receptors (InsP3R), may serve for fine-tuning of local cytosolic Ca(2+) concentration and mediate numerous membrane-to-membrane interactions within the tubular spongiome meshwork. Such activity is suggested by the occurrence of organelle-specific soluble N-ethylmaleimide sensitive factor attachment protein receptor (SNARE) and Ras-related in brain (Rab) proteins, which may regulate functional requirements. For tubulation, F-Bin-amphiphysin-Rvs (F-BAR) proteins are available. In addition, there is indirect evidence for the occurrence of H(+)/Ca(2+) exchangers (to sequester Ca(2+)) and mechanosensitive Ca(2+)-channels (for signaling the filling sate). The periodic activity of the CVC may be regulated by the mechanosensitive Ca(2+)-channels. Such channels are known to colocalize with and to be functionally supported by stomatins, which were recently detected in the CVC. A Kif18-related kinesin motor protein might control the length of radial arms. Two additional InsP3-related channels and several SNAREs are associated with the pore. De novo organelle biogenesis occurs under epigenetic control during mitotic activity and may involve the assembly of γ-tubulin, centrin, calmodulin and a never in mitosis A-type (NIMA) kinase - components also engaged in mitotic processes. PMID:23919298

  7. SIRT3 deficiency impairs mitochondrial and contractile function in the heart.

    PubMed

    Koentges, Christoph; Pfeil, Katharina; Schnick, Tilman; Wiese, Sebastian; Dahlbock, Rabea; Cimolai, Maria C; Meyer-Steenbuck, Maximilian; Cenkerova, Katarina; Hoffmann, Michael M; Jaeger, Carsten; Odening, Katja E; Kammerer, Bernd; Hein, Lutz; Bode, Christoph; Bugger, Heiko

    2015-01-01

    Sirtuin 3 (SIRT3) is a mitochondrial NAD(+)-dependent deacetylase that regulates energy metabolic enzymes by reversible protein lysine acetylation in various extracardiac tissues. The role of SIRT3 in myocardial energetics and in the development of mitochondrial dysfunction in cardiac pathologies, such as the failing heart, remains to be elucidated. To investigate the role of SIRT3 in the regulation of myocardial energetics and function SIRT3(-/-) mice developed progressive age-related deterioration of cardiac function, as evidenced by a decrease in ejection fraction and an increase in enddiastolic volume at 24 but not 8 weeks of age using echocardiography. Four weeks following transverse aortic constriction, ejection fraction was further decreased in SIRT3(-/-) mice compared to WT mice, accompanied by a greater degree of cardiac hypertrophy and fibrosis. In isolated working hearts, a decrease in cardiac function in SIRT3(-/-) mice was accompanied by a decrease in palmitate oxidation, glucose oxidation, and oxygen consumption, whereas rates of glycolysis were increased. Respiratory capacity and ATP synthesis were decreased in cardiac mitochondria of SIRT3(-/-) mice. HPLC measurements revealed a decrease of the myocardial ATP/AMP ratio and of myocardial energy charge. Using LC-MS/MS, we identified increased acetylation of 84 mitochondrial proteins, including 6 enzymes of fatty acid import and oxidation, 50 subunits of the electron transport chain, and 3 enzymes of the tricarboxylic acid cycle. Lack of SIRT3 impairs mitochondrial and contractile function in the heart, likely due to increased acetylation of various energy metabolic proteins and subsequent myocardial energy depletion. PMID:25962702

  8. The SEC6 protein is required for contractile vacuole function in Chlamydomonas reinhardtii.

    PubMed

    Komsic-Buchmann, Karin; Stephan, Lisa Marie; Becker, Burkhard

    2012-06-15

    Contractile vacuoles (CVs) are essential for osmoregulation in many protists. To investigate the mechanism of CV function in Chlamydomonas, we isolated novel osmoregulatory mutants. Four of the isolated mutant cell lines carried the same 33,641 base deletion, rendering the cell lines unable to grow under strong hypotonic conditions. One mutant cell line (Osmo75) was analyzed in detail. The CV morphology was variable in mutant cells, and most cells had multiple small CVs. In addition, one or two enlarged CVs or no visible CVs at all, were observed by light microscopy. These findings suggest that the mutant is impaired in homotypic vacuolar and exocytotic membrane fusion. Furthermore the mutants had long flagella. One of the affected genes is the only SEC6 homologue in Chlamydomonas (CreSEC6). The SEC6 protein is a component of the exocyst complex that is required for efficient exocytosis. Transformation of the Osmo75 mutant with a CreSEC6-GFP construct rescued the mutant completely (osmoregulation and flagellar length). Rescued strains overexpressed CreSEC6 (as a GFP-tagged protein) and displayed a modified CV activity. CVs were larger, whereas the CV contraction interval remained unchanged, leading to increased water efflux rates. Electron microscopy analysis of Osmo75 cells showed that the mutant is able to form the close contact zones between the plasma membrane and the CV membrane observed during late diastole and systole. These results indicate that CreSEC6 is essential for CV function and required for homotypic vesicle fusion during diastole and water expulsion during systole. In addition, CreSEC6 is not only necessary for CV function, but possibly influences the CV cycle in an indirect manner and flagellar length in Chlamydomonas. PMID:22427688

  9. Maintaining PGC-1α expression following pressure overload-induced cardiac hypertrophy preserves angiogenesis but not contractile or mitochondrial function

    PubMed Central

    Pereira, Renata O.; Wende, Adam R.; Crum, Ashley; Hunter, Douglas; Olsen, Curtis D.; Rawlings, Tenley; Riehle, Christian; Ward, Walter F.; Abel, E. Dale

    2014-01-01

    During pathological hypertrophy, peroxisome proliferator-activated receptor coactivator 1α (PGC-1α) is repressed in concert with reduced mitochondrial oxidative capacity and fatty acid oxidation (FAO). We therefore sought to determine if maintaining or increasing PGC-1α levels in the context of pressure overload hypertrophy (POH) would preserve mitochondrial function and prevent contractile dysfunction. Pathological cardiac hypertrophy was induced using 4 wk of transverse aortic constriction (TAC) in mice overexpressing the human PGC-1α genomic locus via a bacterial artificial chromosome (TG) and nontransgenic controls (Cont). PGC-1α levels were increased by 40% in TG mice and were sustained following TAC. Although TAC-induced repression of FAO genes and oxidative phosphorylation (oxphos) genes was prevented in TG mice, mitochondrial function and ATP synthesis were equivalently impaired in Cont and TG mice after TAC. Contractile function was also equally impaired in Cont and TG mice following TAC, as demonstrated by decreased +dP/dt and ejection fraction and increased left ventricular developed pressure and end diastolic pressure. Conversely, capillary density was preserved, in concert with increased VEGF expression, while apoptosis and fibrosis were reduced in TG relative to Cont mice after TAC. Hence, sustaining physiological levels of PGC-1α expression following POH, while preserving myocardial vascularity, does not prevent mitochondrial and contractile dysfunction.—Pereira, R. O., Wende, A. R., Crum, A., Hunter, D., Olsen, C. D., Rawlings, T., Riehle, C., Ward, W. F., Abel, E. D. Maintaining PGC-1α expression following pressure overload-induced cardiac hypertrophy preserves angiogenesis but not contractile or mitochondrial function. PMID:24776744

  10. Skeletal myofiber VEGF is necessary for myogenic and contractile adaptations to functional overload of the plantaris in adult mice.

    PubMed

    Huey, Kimberly A; Smith, Sophia A; Sulaeman, Alexis; Breen, Ellen C

    2016-01-15

    The ability to enhance muscle size and function is important for overall health. In this study, skeletal myofiber vascular endothelial growth factor (VEGF) was hypothesized to regulate hypertrophy, capillarity, and contractile function in response to functional overload (FO). Adult myofiber-specific VEGF gene-ablated mice (skmVEGF(-/-)) and wild-type (WT) littermates underwent plantaris FO or sham surgery (SHAM). Mass, morphology, in vivo function, IGF-1, basic fibroblast growth factor (bFGF), hepatocyte growth factor (HGF), and Akt were measured at 7, 14, and 30 days. FO resulted in hypertrophy in both genotypes, but fiber sizes were 13% and 23% smaller after 14 and 30 days, respectively, and mass 15% less after 30 days in skmVEGF(-/-) than WT. FO increased isometric force after 30 days in WT and decreased in skmVEGF(-/-) after 7 and 14 days. FO also resulted in a reduction in specific force and this differed between genotypes at 14 days. Fatigue resistance improved only in 14-day WT mice. Capillary density was decreased by FO in both genotypes. However, capillary-to-fiber ratios were 19% and 15% lower in skmVEGF(-/-) than WT at the 14- and 30-day time points, respectively. IGF-1 was increased by FO at all time points and was 45% and 40% greater in skmVEGF(-/-) than WT after 7 and 14 days, respectively. bFGF, HGF, total Akt, and phospho-Akt, independent of VEGF expression, and VEGF levels in WT were increased after 7 days of FO. These findings suggest VEGF-dependent capillary maintenance supports muscle growth and function in overloaded muscle and is not rescued by compensatory IGF-1 expression. PMID:26542520

  11. Contractile Defect Caused by Mutation in MYBPC3 Revealed under Conditions Optimized for Human PSC-Cardiomyocyte Function

    PubMed Central

    Birket, Matthew J.; Ribeiro, Marcelo C.; Kosmidis, Georgios; Ward, Dorien; Leitoguinho, Ana Rita; van de Pol, Vera; Dambrot, Cheryl; Devalla, Harsha D.; Davis, Richard P.; Mastroberardino, Pier G.; Atsma, Douwe E.; Passier, Robert; Mummery, Christine L.

    2015-01-01

    Summary Maximizing baseline function of human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) is essential for their effective application in models of cardiac toxicity and disease. Here, we aimed to identify factors that would promote an adequate level of function to permit robust single-cell contractility measurements in a human induced pluripotent stem cell (hiPSC) model of hypertrophic cardiomyopathy (HCM). A simple screen revealed the collaborative effects of thyroid hormone, IGF-1 and the glucocorticoid analog dexamethasone on the electrophysiology, bioenergetics, and contractile force generation of hPSC-CMs. In this optimized condition, hiPSC-CMs with mutations in MYBPC3, a gene encoding myosin-binding protein C, which, when mutated, causes HCM, showed significantly lower contractile force generation than controls. This was recapitulated by direct knockdown of MYBPC3 in control hPSC-CMs, supporting a mechanism of haploinsufficiency. Modeling this disease in vitro using human cells is an important step toward identifying therapeutic interventions for HCM. PMID:26489474

  12. Contractile Defect Caused by Mutation in MYBPC3 Revealed under Conditions Optimized for Human PSC-Cardiomyocyte Function.

    PubMed

    Birket, Matthew J; Ribeiro, Marcelo C; Kosmidis, Georgios; Ward, Dorien; Leitoguinho, Ana Rita; van de Pol, Vera; Dambrot, Cheryl; Devalla, Harsha D; Davis, Richard P; Mastroberardino, Pier G; Atsma, Douwe E; Passier, Robert; Mummery, Christine L

    2015-10-27

    Maximizing baseline function of human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) is essential for their effective application in models of cardiac toxicity and disease. Here, we aimed to identify factors that would promote an adequate level of function to permit robust single-cell contractility measurements in a human induced pluripotent stem cell (hiPSC) model of hypertrophic cardiomyopathy (HCM). A simple screen revealed the collaborative effects of thyroid hormone, IGF-1 and the glucocorticoid analog dexamethasone on the electrophysiology, bioenergetics, and contractile force generation of hPSC-CMs. In this optimized condition, hiPSC-CMs with mutations in MYBPC3, a gene encoding myosin-binding protein C, which, when mutated, causes HCM, showed significantly lower contractile force generation than controls. This was recapitulated by direct knockdown of MYBPC3 in control hPSC-CMs, supporting a mechanism of haploinsufficiency. Modeling this disease in vitro using human cells is an important step toward identifying therapeutic interventions for HCM. PMID:26489474

  13. Mesenteric lymph from rats with trauma-hemorrhagic shock causes abnormal cardiac myocyte function and induces myocardial contractile dysfunction

    PubMed Central

    Sambol, Justin T.; Lee, Marlon A.; Jiang, Mingshan; Dosi, Garima; Dong, Wei; Deitch, Edwin A.

    2011-01-01

    Myocardial contractile dysfunction develops following trauma-hemorrhagic shock (T/HS). We have previously shown that, in a rat fixed pressure model of T/HS (mean arterial pressure of 30–35 mmHg for 90 min), mesenteric lymph duct ligation before T/HS prevented T/HS-induced myocardial contractile depression. To determine whether T/HS lymph directly alters myocardial contractility, we examined the functional effects of physiologically relevant concentrations of mesenteric lymph collected from rats undergoing trauma-sham shock (T/SS) or T/HS on both isolated cardiac myocytes and Langendorff-perfused whole hearts. Acute application of T/HS lymph (0.1–2%), but not T/SS lymph, induced dual inotropic effects on myocytes with an immediate increase in the amplitude of cell shortening (1.4 ± 0.1-fold) followed by a complete block of contraction. Similarly, T/HS lymph caused dual, positive and negative effects on cellular Ca2+ transients. These effects were associated with changes in the electrophysiological properties of cardiac myocytes; T/HS lymph initially prolonged the action potential duration (action potential duration at 90% repolarization, 3.3 ± 0.4-fold), and this was followed by a decrease in the plateau potential and membrane depolarization. Furthermore, intravenous infusion of T/HS lymph, but not T/SS lymph, caused myocardial contractile dysfunction at 24 h after injection, which mimicked actual T/HS-induced changes; left ventricular developed pressure (LVDP) and the maximal rate of LVDP rise and fall (±dP/dtmax) were decreased and inotropic response to Ca2+ was blunted. However, the contractile responsiveness to β-adrenergic receptor stimulation in the T/HS lymph-infused hearts remained unchanged. These results suggest that T/HS lymph directly causes negative inotropic effects on the myocardium and that T/HS lymph-induced changes in myocyte function are likely to contribute to the development of T/HS-induced myocardial dysfunction. PMID:21700891

  14. Receptor for Advanced Glycation End-Products Signaling Interferes with the Vascular Smooth Muscle Cell Contractile Phenotype and Function.

    PubMed

    Simard, Elie; Söllradl, Thomas; Maltais, Jean-Sébastien; Boucher, Julie; D'Orléans-Juste, Pédro; Grandbois, Michel

    2015-01-01

    Increased blood glucose concentrations promote reactions between glucose and proteins to form advanced glycation end-products (AGE). Circulating AGE in the blood plasma can activate the receptor for advanced end-products (RAGE), which is present on both endothelial and vascular smooth muscle cells (VSMC). RAGE exhibits a complex signaling that involves small G-proteins and mitogen activated protein kinases (MAPK), which lead to increased nuclear factor kappa B (NF-κB) activity. While RAGE signaling has been previously addressed in endothelial cells, little is known regarding its impact on the function of VSMC. Therefore, we hypothesized that RAGE signaling leads to alterations in the mechanical and functional properties of VSMC, which could contribute to complications associated with diabetes. We demonstrated that RAGE is expressed and functional in the A7r5 VSMC model, and its activation by AGE significantly increased NF-κB activity, which is known to interfere with the contractile phenotype of VSMC. The protein levels of the contraction-related transcription factor myocardin were also decreased by RAGE activation with a concomitant decrease in the mRNA and protein levels of transgelin (SM-22α), a regulator of VSMC contraction. Interestingly, we demonstrated that RAGE activation increased the overall cell rigidity, an effect that can be related to an increase in myosin activity. Finally, although RAGE stimulation amplified calcium signaling and slightly myosin activity in VSMC challenged with vasopressin, their contractile capacity was negatively affected. Overall, RAGE activation in VSMC could represent a keystone in the development of vascular diseases associated with diabetes by interfering with the contractile phenotype of VSMC through the modification of their mechanical and functional properties. PMID:26248341

  15. Receptor for Advanced Glycation End-Products Signaling Interferes with the Vascular Smooth Muscle Cell Contractile Phenotype and Function

    PubMed Central

    Simard, Elie; Söllradl, Thomas; Maltais, Jean-Sébastien; Boucher, Julie; D’Orléans-Juste, Pédro; Grandbois, Michel

    2015-01-01

    Increased blood glucose concentrations promote reactions between glucose and proteins to form advanced glycation end-products (AGE). Circulating AGE in the blood plasma can activate the receptor for advanced end-products (RAGE), which is present on both endothelial and vascular smooth muscle cells (VSMC). RAGE exhibits a complex signaling that involves small G-proteins and mitogen activated protein kinases (MAPK), which lead to increased nuclear factor kappa B (NF-κB) activity. While RAGE signaling has been previously addressed in endothelial cells, little is known regarding its impact on the function of VSMC. Therefore, we hypothesized that RAGE signaling leads to alterations in the mechanical and functional properties of VSMC, which could contribute to complications associated with diabetes. We demonstrated that RAGE is expressed and functional in the A7r5 VSMC model, and its activation by AGE significantly increased NF-κB activity, which is known to interfere with the contractile phenotype of VSMC. The protein levels of the contraction-related transcription factor myocardin were also decreased by RAGE activation with a concomitant decrease in the mRNA and protein levels of transgelin (SM-22α), a regulator of VSMC contraction. Interestingly, we demonstrated that RAGE activation increased the overall cell rigidity, an effect that can be related to an increase in myosin activity. Finally, although RAGE stimulation amplified calcium signaling and slightly myosin activity in VSMC challenged with vasopressin, their contractile capacity was negatively affected. Overall, RAGE activation in VSMC could represent a keystone in the development of vascular diseases associated with diabetes by interfering with the contractile phenotype of VSMC through the modification of their mechanical and functional properties. PMID:26248341

  16. Insoluble elastin reduces collagen scaffold stiffness, improves viscoelastic properties, and induces a contractile phenotype in smooth muscle cells.

    PubMed

    Ryan, Alan J; O'Brien, Fergal J

    2015-12-01

    Biomaterials with the capacity to innately guide cell behaviour while also displaying suitable mechanical properties remain a challenge in tissue engineering. Our approach to this has been to utilise insoluble elastin in combination with collagen as the basis of a biomimetic scaffold for cardiovascular tissue engineering. Elastin was found to markedly alter the mechanical and biological response of these collagen-based scaffolds. Specifically, during extensive mechanical assessment elastin was found to reduce the specific tensile and compressive moduli of the scaffolds in a concentration dependant manner while having minimal effect on scaffold microarchitecture with both scaffold porosity and pore size still within the ideal ranges for tissue engineering applications. However, the viscoelastic properties were significantly improved with elastin addition with a 3.5-fold decrease in induced creep strain, a 6-fold increase in cyclical strain recovery, and with a four-parameter viscoelastic model confirming the ability of elastin to confer resistance to long term deformation/creep. Furthermore, elastin was found to result in the modulation of SMC phenotype towards a contractile state which was determined via reduced proliferation and significantly enhanced expression of early (α-SMA), mid (calponin), and late stage (SM-MHC) contractile proteins. This allows the ability to utilise extracellular matrix proteins alone to modulate SMC phenotype without any exogenous factors added. Taken together, the ability of elastin to alter the mechanical and biological response of collagen scaffolds has led to the development of a biomimetic biomaterial highly suitable for cardiovascular tissue engineering. PMID:26431909

  17. Inhibition of AMPK accentuates prolonged caloric restriction-induced change in cardiac contractile function through disruption of compensatory autophagy.

    PubMed

    Zheng, Qijun; Zhao, Kun; Han, Xuefeng; Huff, Anna F; Cui, Qin; Babcock, Sara A; Yu, Shiqiang; Zhang, Yingmei

    2015-02-01

    Prolonged caloric restriction often results in alteration in heart geometry and function although the underlying mechanism remains poorly defined. Autophagy, a conserved pathway for bulk degradation of intracellular proteins and organelles, preserves energy and nutrient in the face of caloric insufficiency. This study was designed to examine the role of AMPK in prolonged caloric restriction-induced change in cardiac homeostasis and the underlying mechanism(s) involved with a focus on autophagy. Wild-type (WT) and AMPK kinase dead (KD) mice were caloric restricted (by 40%) for 30 weeks. Echocardiographic, cardiomyocyte contractile and intracellular Ca²⁺ properties, autophagy and autophagy regulatory proteins were evaluated. Caloric restriction compromised echocardiographic indices (decreased ventricular mass, left ventricular diameters, and cardiac output), cardiomyocyte contractile and intracellular Ca²⁺ properties associated with upregulated autophagy (Beclin-1, Atg5 and LC3BII-to-LC3BI ratio), increased autophagy adaptor protein p62, elevated phosphorylation of AMPK and TSC1/2, depressed phosphorylation of mTOR and ULK1. Although AMPK inhibition did not affect cardiac mechanical function, autophagy and autophagy signaling proteins, it significantly accentuated caloric restriction-induced changes in myocardial contractile function and intracellular Ca²⁺ handling. Interestingly, AMPK inhibition reversed caloric restriction-induced changes in autophagy and autophagy signaling. AMPK inhibition led to dampened levels of Beclin-1, Atg 5 and LC3B ratio along with suppressed phosphorylation of AMPK and TSC1/2 as well as elevated phosphorylation of mTOR and ULK1. Taken together, these data suggest an indispensible role for AMPK in the maintenance of cardiac homeostasis under prolonged caloric restriction-induced pathological changes possibly through autophagy regulation. This article is part of a Special Issue entitled: Autophagy and protein quality control in

  18. Mechanisms of exercise-induced improvements in the contractile apparatus of the mammalian myocardium.

    PubMed

    Kemi, O J; Wisløff, U

    2010-08-01

    One of the main outcomes of aerobic endurance exercise training is the improved maximal oxygen uptake, and this is pivotal to the improved work capacity that follows the exercise training. Improved maximal oxygen uptake in turn is at least partly achieved because exercise training increases the ability of the myocardium to produce a greater cardiac output. In healthy subjects, this has been demonstrated repeatedly over many decades. It has recently emerged that this scenario may also be true under conditions of an initial myocardial dysfunction. For instance, myocardial improvements may still be observed after exercise training in post-myocardial infarction heart failure. In both health and disease, it is the changes that occur in the individual cardiomyocytes with respect to their ability to contract that by and large drive the exercise training-induced adaptation to the heart. Here, we review the evidence and the mechanisms by which exercise training induces beneficial changes in the mammalian myocardium, as obtained by means of experimental and clinical studies, and argue that these changes ultimately alter the function of the whole heart and contribute to the changes in whole-body function. PMID:20353489

  19. Role of histidyl dipeptides in contractile function of fast and slow motor units in rat skeletal muscle.

    PubMed

    Kaczmarek, Dominik; Łochyński, Dawid; Everaert, Inge; Pawlak, Maciej; Derave, Wim; Celichowski, Jan

    2016-07-01

    The physiological role of the muscle histidyl dipeptides carnosine and anserine in contractile function of various types of muscle fibers in vivo is poorly understood. Ten adult male Wistar rats were randomly assigned to two groups: control and supplemented for 10 wk with beta-alanine, the precursor of carnosine (∼640 mg·kg body wt(-1)·day(-1)). Thereafter, contractile properties and fatigability of isolated fast fatigable (FF), fast resistant to fatigue (FR), and slow motor units (MUs) from the medial gastrocnemius were determined in deeply anaesthetized animals. The fatigue resistance was tested with a 40-Hz fatigue protocol followed by a second protocol at 40 Hz in fast and 20 Hz in slow units. In the supplemented rats, histidyl dipeptide concentrations significantly increased (P < 0.05) by 25% in the red portion of the gastrocnemius, and carnosine increased by 94% in the white portion. The twitch force of FF units and maximum tetanic force of FR units were significantly increased (P < 0.05), and the half-relaxation time was prolonged in slow units (P < 0.05). FF units showed less fatigue during the first 10 s, and FR units showed higher forces between 10 and 60 s during the 40-Hz fatigue test. In slow units, forces declined less during the first 60 s of the 20-Hz test. In conclusion, this in vivo experiment demonstrates that an elevation in muscle histidyl dipeptide content elicits beneficial changes in MU contractile characteristics and fatigue resistance. Carnosine and anserine seem to play an important yet divergent role in various MUs. PMID:27197862

  20. Regular exercise improves cardiac contractile activation by modulating MHC isoforms and SERCA activity in orchidectomized rats.

    PubMed

    Vutthasathien, Pavarana; Wattanapermpool, Jonggonnee

    2015-10-01

    Data from the trial known as Testosterone in Older Men with Mobility Limitations (TOM) has indicated an association between testosterone administration and a greater risk for adverse cardiovascular events. We therefore propose that regular exercise is a cardioprotective alternative that prevents detrimental changes in contractile activation when a deficiency in male sex hormones exists. Ten-week-old orchidectomized (ORX) rats were subjected to a 9-wk treadmill running program at moderate intensity starting 1 wk after surgery. Although exercise-induced cardiac hypertrophy was observed both in rats that underwent ORX and sham surgery, regular exercise enhanced cardiac myofilament Ca(2+) sensitivity and myosin light-chain 2 phosphorylation only in rats that underwent a sham operation. Although the rats that had sham surgery and and given exercise exhibited no change in maximum developed tension, regular running prevented the suppression of maximum active tension in the hearts of ORX rats. Regular exercise also prevented a shift in myosin heavy chain (MHC) isoforms toward β-MHC, a reduction in sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) activity, and an increase in SERCA sensitivity in the hearts of ORX rats. Neither SERCA content nor its modulating component, phospholamban (PLB), was altered by exercise in either sham-operated or ORX rats. However, decreases in the phosphorylated Thr(17) form of PLB and the phosphorylated Thr(287) form of Ca(2+)/calmodulin-dependent kinase II in the hearts of ORX rats were abolished after regular exercise. These results thus support the use of regular running as a cardioprotective alternative to testosterone replacement in hypogonadal conditions. PMID:26272317

  1. Green tea extract given before regional myocardial ischemia-reperfusion in rats improves myocardial contractility by attenuating calcium overload.

    PubMed

    Liou, Ying-Ming; Hsieh, Shih-Rong; Wu, Tsu-Juey; Chen, Jan-Yow

    2010-11-01

    There is evidence for a negative correlation between green tea consumption and cardiovascular diseases. The aim of the present study was to examine whether green tea extract (GTE) given before regional myocardial ischemia could improve depression of myocardial contractility by preventing cytosolic Ca(2+) overload. Regional ischemia-reperfusion (IR) was induced in rats by ligating the left anterior descending branch for 20 min, then releasing the ligature. Ligation induced ventricular arrhythmias in rats without GTE pretreatment, but decreased arrhythmogenesis was seen in rats pretreated 30 min earlier with GTE (400 mg/kg). During reperfusion, arrhythmias only occurred during the initial 5 min, and GTE pretreatment had no effect. After overnight recovery, serum cTnI levels were greatly increased in control post-IR rats but only slightly elevated in GTE-pretreated post-IR rats. Myocardial contractility measured by echocardiography was still depressed after 3 days in control post-IR rats, but not in GTE-pretreated post-IR rats. No myocardial ischemic injury was seen in post-IR rats with or without GTE pretreatment. Using freshly isolated single heart myocytes, GTE was found to attenuate the post-IR injury-associated cytosolic Ca(2+) overload and modulate changes in the levels and distribution of myofibril, adherens junction, and gap junction proteins. In summary, GTE pretreatment protects cardiomyocytes from IR injury by preventing cytosolic Ca(2+) overload, myofibril disruption, and alterations in adherens and gap junction protein expression and distribution. PMID:20922441

  2. Inhibition of Contractile Function in Human Joint Capsule Myofibroblasts by Targeting the TGF-β1 and PDGF Pathways

    PubMed Central

    Martin, Anne; Ritz, Ulrike; Baranowski, Andreas; Ossendorf, Christian; Rommens, Pol M.; Hofmann, Alexander

    2016-01-01

    Background Contractile myofibroblasts (MFs) accumulate in the joint capsules of patients suffering from posttraumatic joint stiffness. MF activation is controlled by a complex local network of growth factors and cytokines, ending in the increased production of extracellular matrix components followed by soft tissue contracture. Despite the tremendous growth of knowledge in this field, inconsistencies remain in practice and prevention. Methods and Findings In this in vitro study, we isolated and cultured alpha-smooth muscle actin (α-SMA) positive human joint capsule MFs from biopsy specimens and investigated the effect of profibrotic and antifibrotic agents on MF function. Both TGF-β1 and PDGF significantly induced proliferation and increased extracellular matrix contraction in an established 3D collagen gel contraction model. Furthermore, both growth factors induced α-SMA and collagen type I gene expression in MFs. TGF-β1 down-regulated TGF-β1 and TGF-β receptor (R) 1 and receptor (R) 2 gene expression, while PDGF selectively down-regulated TGF-β receptor 2 gene expression. These effects were blocked by suramin. Interestingly, the anti-oxidant agent superoxide dismutase (SOD) blocked TGF-β1 induced proliferation and collagen gel contraction without modulating the gene expression of α-SMA, collagen type I, TGF-β1, TGF-β R1 and TGF-β R2. Conclusions Our results provide evidence that targeting the TGF-β1 and PDGF pathways in human joint capsule MFs affects their contractile function. TGF-β1 may modulate MF function in the joint capsule not only via the receptor signalling pathway but also by regulating the production of profibrotic reactive oxygen species (ROS). In particular, anti-oxidant agents could offer promising options in developing strategies for the prevention and treatment of posttraumatic joint stiffness in humans. PMID:26730954

  3. Functional Loss of Bmsei Causes Thermosensitive Epilepsy in Contractile Mutant Silkworm, Bombyx mori

    NASA Astrophysics Data System (ADS)

    Nie, Hongyi; Cheng, Tingcai; Huang, Xiaofeng; Zhou, Mengting; Zhang, Yinxia; Dai, Fangyin; Mita, Kazuei; Xia, Qingyou; Liu, Chun

    2015-07-01

    The thermoprotective mechanisms of insects remain largely unknown. We reported the Bombyx mori contractile (cot) behavioral mutant with thermo-sensitive seizures phenotype. At elevated temperatures, the cot mutant exhibit seizures associated with strong contractions, rolling, vomiting, and a temporary lack of movement. We narrowed a region containing cot to ~268 kb by positional cloning and identified the mutant gene as Bmsei which encoded a potassium channel protein. Bmsei was present in both the cell membrane and cytoplasm in wild-type ganglia but faint in cot. Furthermore, Bmsei was markedly decreased upon high temperature treatment in cot mutant. With the RNAi method and injecting potassium channel blockers, the wild type silkworm was induced the cot phenotype. These results demonstrated that Bmsei was responsible for the cot mutant phenotype and played an important role in thermoprotection in silkworm. Meanwhile, comparative proteomic approach was used to investigate the proteomic differences. The results showed that the protein of Hsp-1 and Tn1 were significantly decreased and increased on protein level in cot mutant after thermo-stimulus, respectively. Our data provide insights into the mechanism of thermoprotection in insect. As cot phenotype closely resembles human epilepsy, cot might be a potential model for the mechanism of epilepsy in future.

  4. Synergist muscle ablation and recovery from nerve-repair grafting: contractile and metabolic function

    PubMed Central

    Larkin, Lisa M.; Kuzon, William M.; Halter, Jeffrey B.

    2009-01-01

    After nerve-repair grafting of medial gastrocnemius muscle, there is incomplete recovery of specific force and sustainable power, perhaps due to overcompensation by synergistic muscles. We hypothesized that increased workload due to synergist ablation would enhance graft recovery. Contractile and metabolic properties of control and nerve-repair grafted muscles, with and without synergist ablation, were determined after 120 days recovery. Specific force (N/cm2) and normalized power (W/kg) were less in the experimental groups compared with controls. Sustained power (W/kg) in the synergist-ablated nerve-repair grafted muscle was higher than nerve-repair grafted muscle, returning to control values. GLUT-4 protein was higher and glycogen content was diminished in both synergist-ablated groups. In summary, synergist ablation did not enhance the recovery of specific force or normalized power, but sustained power did recover, suggesting that metabolic and not mechanical parameters were responsible for this recovery. The enhanced endurance after synergist ablation was accompanied by increased GLUT-4 protein, suggesting a role for increased uptake of circulating glucose during contraction. PMID:11007584

  5. Sarcoplasmic reticulum function and muscle contractile character following fatiguing exercise in humans

    PubMed Central

    Hill, Christopher A; Thompson, Martin W; Ruell, Patricia A; Thom, Jeanette M; White, Michael J

    2001-01-01

    This study examined the alterations in calcium release, calcium uptake and calcium ATPase activity of skeletal muscle sarcoplasmic reticulum in response to a bout of intense dynamic knee extensor exercise, and the relationship between these changes and alterations in muscle contractile characteristics in the human quadriceps. In biopsy samples taken from the vastus lateralis, sarcoplasmic reticulum calcium release and calcium uptake were significantly depressed (P < 0.01 and 0.05, respectively) immediately following the exercise with no alteration in the sarcoplasmic reticulum Ca2+-ATPase activity. A 33 % reduction in the maximum voluntary isometric torque was found following the exercise, with reduced torques from electrically evoked isometric contractions at low frequencies of stimulation (10 and 20 Hz) but not at higher frequencies (50 and 100 Hz). The depressed calcium release was correlated (P < 0.05) with a decreased ratio of torques generated at 20:50 Hz, indicating an involvement in low frequency fatigue; however, no correlations between the muscle relaxation times or rates of change of torque and calcium uptake were observed. PMID:11251066

  6. Functional Loss of Bmsei Causes Thermosensitive Epilepsy in Contractile Mutant Silkworm, Bombyx mori

    PubMed Central

    Nie, Hongyi; Cheng, Tingcai; Huang, Xiaofeng; Zhou, Mengting; Zhang, Yinxia; Dai, Fangyin; Mita, Kazuei; Xia, Qingyou; Liu, Chun

    2015-01-01

    The thermoprotective mechanisms of insects remain largely unknown. We reported the Bombyx mori contractile (cot) behavioral mutant with thermo-sensitive seizures phenotype. At elevated temperatures, the cot mutant exhibit seizures associated with strong contractions, rolling, vomiting, and a temporary lack of movement. We narrowed a region containing cot to ~268 kb by positional cloning and identified the mutant gene as Bmsei which encoded a potassium channel protein. Bmsei was present in both the cell membrane and cytoplasm in wild-type ganglia but faint in cot. Furthermore, Bmsei was markedly decreased upon high temperature treatment in cot mutant. With the RNAi method and injecting potassium channel blockers, the wild type silkworm was induced the cot phenotype. These results demonstrated that Bmsei was responsible for the cot mutant phenotype and played an important role in thermoprotection in silkworm. Meanwhile, comparative proteomic approach was used to investigate the proteomic differences. The results showed that the protein of Hsp-1 and Tn1 were significantly decreased and increased on protein level in cot mutant after thermo-stimulus, respectively. Our data provide insights into the mechanism of thermoprotection in insect. As cot phenotype closely resembles human epilepsy, cot might be a potential model for the mechanism of epilepsy in future. PMID:26198671

  7. Abnormalities in intracellular calcium regulation and contractile function in myocardium from dogs with pacing-induced heart failure.

    PubMed Central

    Perreault, C L; Shannon, R P; Komamura, K; Vatner, S F; Morgan, J P

    1992-01-01

    24 d of rapid ventricular pacing induced dilated cardiomyopathy with both systolic and diastolic dysfunction in conscious, chronically instrumented dogs. We studied mechanical properties and intracellular calcium (Ca2+i) transients of trabeculae carneae isolated from 15 control dogs (n = 32) and 11 dogs with pacing-induced cardiac failure (n = 26). Muscles were stretched to maximum length at 30 degrees C and stimulated at 0.33 Hz; a subset (n = 17 control, n = 17 myopathic) was loaded with the [Ca2+]i indicator aequorin. Peak tension was depressed in the myopathic muscles, even in the presence of maximally effective (i.e., 16 mM) [Ca2+] in the perfusate. However, peak [Ca2+]i was similar (0.80 +/- 0.13 vs. 0.71 +/- 0.05 microM; [Ca2+]o = 2.5 mM), suggesting that a decrease in Cai2+ availability was not responsible for the decreased contractility. The time for decline from the peak of the Cai2+ transient was prolonged in the myopathic group, which correlated with prolongation of isometric contraction and relaxation. However, similar end-diastolic [Ca2+]i was achieved in both groups (0.29 +/- 0.05 vs. 0.31 +/- 0.02 microM), indicating that Cai2+ homeostasis can be maintained in myopathic hearts. The inotropic response of the myopathic muscles to milrinone was depressed compared with the controls. However, when cAMP production was stimulated by pretreatment with forskolin, the response of the myopathic muscles to milrinone was improved. Our findings provide direct evidence that abnormal [Ca2+]i handling is an important cause of contractile dysfunction in dogs with pacing-induced heart failure and suggest that deficient production of cAMP may be an important cause of these changes in excitation-contraction coupling. PMID:1311723

  8. Abnormalities in intracellular calcium regulation and contractile function in myocardium from dogs with pacing-induced heart failure

    NASA Technical Reports Server (NTRS)

    Perreault, C. L.; Shannon, R. P.; Komamura, K.; Vatner, S. F.; Morgan, J. P.

    1992-01-01

    24 d of rapid ventricular pacing induced dilated cardiomyopathy with both systolic and diastolic dysfunction in conscious, chronically instrumented dogs. We studied mechanical properties and intracellular calcium (Ca2+i) transients of trabeculae carneae isolated from 15 control dogs (n = 32) and 11 dogs with pacing-induced cardiac failure (n = 26). Muscles were stretched to maximum length at 30 degrees C and stimulated at 0.33 Hz; a subset (n = 17 control, n = 17 myopathic) was loaded with the [Ca2+]i indicator aequorin. Peak tension was depressed in the myopathic muscles, even in the presence of maximally effective (i.e., 16 mM) [Ca2+] in the perfusate. However, peak [Ca2+]i was similar (0.80 +/- 0.13 vs. 0.71 +/- 0.05 microM; [Ca2+]o = 2.5 mM), suggesting that a decrease in Cai2+ availability was not responsible for the decreased contractility. The time for decline from the peak of the Cai2+ transient was prolonged in the myopathic group, which correlated with prolongation of isometric contraction and relaxation. However, similar end-diastolic [Ca2+]i was achieved in both groups (0.29 +/- 0.05 vs. 0.31 +/- 0.02 microM), indicating that Cai2+ homeostasis can be maintained in myopathic hearts. The inotropic response of the myopathic muscles to milrinone was depressed compared with the controls. However, when cAMP production was stimulated by pretreatment with forskolin, the response of the myopathic muscles to milrinone was improved. Our findings provide direct evidence that abnormal [Ca2+]i handling is an important cause of contractile dysfunction in dogs with pacing-induced heart failure and suggest that deficient production of cAMP may be an important cause of these changes in excitation-contraction coupling.

  9. Integrative Effect of Carvedilol and Aerobic Exercise Training Therapies on Improving Cardiac Contractility and Remodeling in Heart Failure Mice

    PubMed Central

    Vanzelli, Andréa S.; Medeiros, Alessandra; Rolim, Natale; Bartholomeu, Jan B.; Cunha, Telma F.; Bechara, Luiz G.; Gomes, Enéas R. M.; Mattos, Katt C.; Sirvente, Raquel; Salemi, Vera; Mady, Charles; Negrao, Carlos E.; Guatimosim, Silvia; Brum, Patricia C.

    2013-01-01

    The use of β-blockers is mandatory for counteracting heart failure (HF)-induced chronic sympathetic hyperactivity, cardiac dysfunction and remodeling. Importantly, aerobic exercise training, an efficient nonpharmacological therapy to HF, also counteracts sympathetic hyperactivity in HF and improves exercise tolerance and cardiac contractility; the latter associated with changes in cardiac Ca2+ handling. This study was undertaken to test whether combined β–blocker and aerobic exercise training would integrate the beneficial effects of isolated therapies on cardiac structure, contractility and cardiomyocyte Ca2+ handling in a genetic model of sympathetic hyperactivity-induced HF (α2A/α2C- adrenergic receptor knockout mice, KO). We used a cohort of 5–7 mo male wild-type (WT) and congenic mice (KO) with C57Bl6/J genetic background randomly assigned into 5 groups: control (WT), saline-treated KO (KOS), exercise trained KO (KOT), carvedilol-treated KO (KOC) and, combined carvedilol-treated and exercise-trained KO (KOCT). Isolated and combined therapies reduced mortality compared with KOS mice. Both KOT and KOCT groups had increased exercise tolerance, while groups receiving carvedilol had increased left ventricular fractional shortening and reduced cardiac collagen volume fraction compared with KOS group. Cellular data confirmed that cardiomyocytes from KOS mice displayed abnormal Ca2+ handling. KOT group had increased intracellular peak of Ca2+ transient and reduced diastolic Ca2+ decay compared with KOS group, while KOC had increased Ca2+ decay compared with KOS group. Notably, combined therapies re-established cardiomyocyte Ca2+ transient paralleled by increased SERCA2 expression and SERCA2:PLN ratio toward WT levels. Aerobic exercise trained increased the phosphorylation of PLN at Ser16 and Thr17 residues in both KOT and KOCT groups, but carvedilol treatment reduced lipid peroxidation in KOC and KOCT groups compared with KOS group. The present findings

  10. Expression of mitochondrial regulatory genes parallels respiratory capacity and contractile function in a rat model of hypoxia-induced right ventricular hypertrophy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chronic hypobaric hypoxia (CHH) increases load on the right ventricle (RV) resulting in RV hypertrophy. We hypothesized that CHH elicits distinct responses, i.e., the hypertrophied RV, unlike the left ventricle (LV), displaying enhanced mitochondrial respiratory and contractile function. Wistar rats...

  11. Single acute stress-induced progesterone and ovariectomy alter cardiomyocyte contractile function in female rats

    PubMed Central

    Kalász, Judit; Tóth, Enikő Pásztor; Bódi, Beáta; Fagyas, Miklós; Tóth, Attila; Pal, Bhattoa Harjit; Vári, Sándor G.; Balog, Marta; Blažetić, Senka; Heffer, Marija; Papp, Zoltán; Borbély, Attila

    2014-01-01

    Aim To assess how ovarian-derived sex hormones (in particular progesterone) modify the effects of single acute stress on the mechanical and biochemical properties of left ventricular cardiomyocytes in the rat. Methods Non-ovariectomized (control, n = 8) and ovariectomized (OVX, n = 8) female rats were kept under normal conditions or were exposed to stress (control-S, n = 8 and OVX-S, n = 8). Serum progesterone levels were measured using a chemiluminescent immunoassay. Left ventricular myocardial samples were used for isometric force measurements and protein analysis. Ca2+-dependent active force (Factive), Ca2+-independent passive force (Fpassive), and Ca2+-sensitivity of force production were determined in single, mechanically isolated, permeabilized cardiomyocytes. Stress- and ovariectomy-induced alterations in myofilament proteins (myosin-binding protein C [MyBP-C], troponin I [TnI], and titin) were analyzed by sodium dodecyl sulfate gel electrophoresis using protein and phosphoprotein stainings. Results Serum progesterone levels were significantly increased in stressed rats (control-S, 35.6 ± 4.8 ng/mL and OVX-S, 21.9 ± 4.0 ng/mL) compared to control (10 ± 2.9 ng/mL) and OVX (2.8 ± 0.5 ng/mL) groups. Factive was higher in the OVX groups (OVX, 25.9 ± 3.4 kN/m2 and OVX-S, 26.3 ± 3.0 kN/m2) than in control groups (control, 16.4 ± 1.2 kN/m2 and control-S, 14.4 ± 0.9 kN/m2). Regarding the potential molecular mechanisms, Factive correlated with MyBP-C phosphorylation, while myofilament Ca2+-sensitivity inversely correlated with serum progesterone levels when the mean values were plotted for all animal groups. Fpassive was unaffected by any treatment. Conclusion Stress increases ovary-independent synthesis and release of progesterone, which may regulate Ca2+-sensitivity of force production in left ventricular cardiomyocytes. Stress and female hormones differently alter Ca2+-dependent cardiomyocyte contractile

  12. Work Capacity of the Bladder During Voiding: A Novel Method to Evaluate Bladder Contractile Function and Bladder Outlet Obstruction

    PubMed Central

    Liu, Ning; Man, Li-Bo; He, Feng; Huang, Guang-Lin; Zhou, Ning; Zhu, Xiao-Fei

    2015-01-01

    Background: Work in voiding (WIV) of the bladder may be used to evaluate bladder status throughout urination rather than at a single time point. Few studies, however, have assessed WIV owing to the complexity of its calculations. We have developed a method of calculating work capacity of the bladder while voiding and analyzed the associations of bladder work parameters with bladder contractile function and bladder outlet obstruction (BOO). Methods: The study retrospectively evaluated 160 men and 23 women, aged >40 years and with a detrusor pressure at maximal flow rate (Pdet Qmax) of ≥40 cmH2O in men, who underwent urodynamic testing. The bladder power integration method was used to calculate WIV; WIV per second (WIV/t) and WIV per liter of urine voided (WIV/v) were also calculated. In men, the relationships between these work capacity parameters and Pdet Qmax and Abrams-Griffiths (AG) number were determined using linear-by-linear association tests, and relationships between work capacity parameters and BOO grade were investigated using Spearman's association test. Results: The mean WIV was 1.15 ± 0.78 J and 1.30 ± 0.88 J, mean WIV/t was 22.95 ± 14.45 mW and 23.78 ± 17.02 mW, and mean WIV/v was 5.59 ± 2.32 J/L and 2.83 ± 1.87 J/L in men and women, respectively. In men, WIV/v showed significant positive associations with Pdet Qmax (r = 0.845, P = 0.000), AG number (r = 0.814, P = 0.000), and Schafer class (r = 0.726, P = 0.000). Conversely, WIV and WIV/t showed no associations with Pdet Qmax or AG number. In patients with BOO (Schafer class > II), WIV/v correlated positively with increasing BOO grade. Conclusions: WIV can be calculated from simple urodynamic parameters using the bladder power integration method. WIV/v may be a marker of BOO grade, and the bladder contractile function can be evaluated by WIV and WIV/t. PMID:26668148

  13. Cardiac troponin structure-function and the influence of hypertrophic cardiomyopathy associated mutations on modulation of contractility.

    PubMed

    Cheng, Yuanhua; Regnier, Michael

    2016-07-01

    Cardiac troponin (cTn) acts as a pivotal regulator of muscle contraction and relaxation and is composed of three distinct subunits (cTnC: a highly conserved Ca(2+) binding subunit, cTnI: an actomyosin ATPase inhibitory subunit, and cTnT: a tropomyosin binding subunit). In this mini-review, we briefly summarize the structure-function relationship of cTn and its subunits, its modulation by PKA-mediated phosphorylation of cTnI, and what is known about how these properties are altered by hypertrophic cardiomyopathy (HCM) associated mutations of cTnI. This includes recent work using computational modeling approaches to understand the atomic-based structural level basis of disease-associated mutations. We propose a viewpoint that it is alteration of cTnC-cTnI interaction (rather than the Ca(2+) binding properties of cTn) per se that disrupt the ability of PKA-mediated phosphorylation at cTnI Ser-23/24 to alter contraction and relaxation in at least some HCM-associated mutations. The combination of state of the art biophysical approaches can provide new insight on the structure-function mechanisms of contractile dysfunction resulting cTnI mutations and exciting new avenues for the diagnosis, prevention, and even treatment of heart diseases. PMID:26851561

  14. STIM1 signaling controls store operated calcium entry required for development and contractile function in skeletal muscle

    PubMed Central

    Stiber, Jonathan; Hawkins, April; Zhang, Zhu-Shan; Wang, Sunny; Burch, Jarrett; Graham, Victoria; Ward, Cary C.; Seth, Malini; Finch, Elizabeth; Malouf, Nadia; Williams, R. Sanders; Eu, Jerry P.; Rosenberg, Paul

    2009-01-01

    It is now well established that stromal interaction molecule 1 (STIM1) is the calcium sensor of endoplasmic reticulum (ER) stores required to activate store-operated calcium entry (SOC) channels at the surface of non-excitable cells. Yet little is known about STIM1 in excitable cells such as striated muscle where the complement of calcium regulatory molecules is rather disparate from that of non-excitable cells. Here, we show that STIM1 is expressed in both myotubes and adult skeletal muscle. Myotubes lacking functional STIM1 fail to exhibit SOC and fatigue rapidly. Moreover, mice lacking functional STIM1 die perinatally from a skeletal myopathy. In addition, STIM1 haploinsufficiency confers a contractile defect only under conditions where rapid refilling of stores would be needed. These findings provide novel insight to the role of STIM1 in skeletal muscle and suggest that STIM1 has a universal role as an ER/SR calcium sensor in both excitable and non-excitable cells. PMID:18488020

  15. Micropost arrays for measuring stem cell-derived cardiomyocyte contractility.

    PubMed

    Beussman, Kevin M; Rodriguez, Marita L; Leonard, Andrea; Taparia, Nikita; Thompson, Curtis R; Sniadecki, Nathan J

    2016-02-01

    Stem cell-derived cardiomyocytes have the potential to be used to study heart disease and maturation, screen drug treatments, and restore heart function. Here, we discuss the procedures involved in using micropost arrays to measure the contractile forces generated by stem cell-derived cardiomyocytes. Cardiomyocyte contractility is needed for the heart to pump blood, so measuring the contractile forces of cardiomyocytes is a straightforward way to assess their function. Microfabrication and soft lithography techniques are utilized to create identical arrays of flexible, silicone microposts from a common master. Micropost arrays are functionalized with extracellular matrix protein to allow cardiomyocytes to adhere to the tips of the microposts. Live imaging is used to capture videos of the deflection of microposts caused by the contraction of the cardiomyocytes. Image analysis code provides an accurate means to quantify these deflections. The contractile forces produced by a beating cardiomyocyte are calculated by modeling the microposts as cantilever beams. We have used this assay to assess techniques for improving the maturation and contractile function of stem cell-derived cardiomyocytes. PMID:26344757

  16. Contractility parameters of human β-cardiac myosin with the hypertrophic cardiomyopathy mutation R403Q show loss of motor function

    PubMed Central

    Nag, Suman; Sommese, Ruth F.; Ujfalusi, Zoltan; Combs, Ariana; Langer, Stephen; Sutton, Shirley; Leinwand, Leslie A.; Geeves, Michael A.; Ruppel, Kathleen M.; Spudich, James A.

    2015-01-01

    Hypertrophic cardiomyopathy (HCM) is the most frequently occurring inherited cardiovascular disease. It is caused by mutations in genes encoding the force-generating machinery of the cardiac sarcomere, including human β-cardiac myosin. We present a detailed characterization of the most debated HCM-causing mutation in human β-cardiac myosin, R403Q. Despite numerous studies, most performed with nonhuman or noncardiac myosin, there is no consensus about the mechanism of action of this mutation on the function of the enzyme. We use recombinant human β-cardiac myosin and new methodologies to characterize in vitro contractility parameters of the R403Q myosin compared to wild type. We extend our studies beyond pure actin filaments to include the interaction of myosin with regulated actin filaments containing tropomyosin and troponin. We find that, with pure actin, the intrinsic force generated by R403Q is ~15% lower than that generated by wild type. The unloaded velocity is, however, ~10% higher for R403Q myosin, resulting in a load-dependent velocity curve that has the characteristics of lower contractility at higher external loads compared to wild type. With regulated actin filaments, there is no increase in the unloaded velocity and the contractility of the R403Q myosin is lower than that of wild type at all loads. Unlike that with pure actin, the actin-activated adenosine triphosphatase activity for R403Q myosin with Ca2+-regulated actin filaments is ~30% lower than that for wild type, predicting a lower unloaded duty ratio of the motor. Overall, the contractility parameters studied fit with a loss of human β-cardiac myosin contractility as a result of the R403Q mutation. PMID:26601291

  17. Physiological Reduction in Left Ventricular Contractile Function in Healthy Postpartum Women: Potential Overlap with Peripartum Cardiomyopathy

    PubMed Central

    Khan, Sitara G.; Melikian, Narbeh; Mushemi-Blake, Sitali; Dennes, William; Jouhra, Fadi; Monaghan, Mark; Shah, Ajay M.

    2016-01-01

    Aims Peripartum cardiomyopathy is a potentially life-threatening cause of heart failure, commoner in Afro-Caribbean than Caucasian women. Its diagnosis can be challenging due to physiological changes in cardiac function that also occur in healthy women during the early postpartum period. This study aimed to (i) establish the overlap between normal cardiac physiology in the immediate postpartum period and pathological changes in peripartum cardiomyopathy ii) identify any ethnicity-specific changes in cardiac function and cardiac biomarkers in healthy postpartum women. Methods and Results We conducted a cross-sectional study of 58 healthy postpartum women within 48 hours of delivery and 18 matched non-pregnant controls. Participants underwent cardiac assessment by echocardiography and strain analysis, including 3D echocardiography in 40 postpartum women. Results were compared with 12 retrospectively studied peripartum cardiomyopathy patients. Healthy postpartum women had significantly higher left ventricular volumes and mass, and lower ejection fraction and global longitudinal strain than non-pregnant controls. These parameters were significantly more impaired in peripartum cardiomyopathy patients but with overlapping ranges of values. Healthy postpartum women had higher levels of adrenomedullin, placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt1) compared to controls. The postpartum state, adrenomedullin, sFlt1 and the sFlt1:PlGF ratio were independent predictors of LV remodelling and function in healthy postpartum women. Conclusion Healthy postpartum women demonstrate several echocardiographic indicators of left ventricular remodelling and reduced function, which are associated with altered levels of angiogenic and cardiac biomarkers. PMID:26859567

  18. Myosin Phosphatase Isoforms as Determinants of Smooth Muscle Contractile Function and Calcium Sensitivity of Force Production

    PubMed Central

    DIPPOLD, RACHAEL P.; FISHER, STEVEN A.

    2014-01-01

    The dephosphorylation of myosin by the MP causes smooth muscle relaxation. MP is also a key target of signals that regulate vascular tone and thus blood flow and pressure. Here, we review studies from the past two decades that support the hypothesis that the regulated expression of MP subunits is a critical determinant of smooth muscle responses to constrictor and dilator signals. In particular, the highly regulated splicing of the regulatory subunit Mypt1 Exon 24 is proposed to tune sensitivity to NO/cGMP-mediated relaxation. The regulated transcription of the MP inhibitory subunit CPI-17 is proposed to determine sensitivity to agonist-mediated constriction. The expression of these subunits is specific in the microcirculation and varies in developmental and disease contexts. To date, the relationship between MP subunit expression and vascular function in these different contexts is correlative; confirmation of the hypothesis will require the generation of genetically engineered mice to test the role of MP subunits and their isoforms in the specificity of vascular smooth muscle responses to constrictor and dilator signals. PMID:24112301

  19. Frequency dependence of power and its implications for contractile function of muscle fibers from the digital flexors of horses.

    PubMed

    Butcher, Michael T; Bertram, John E A; Syme, Douglas A; Hermanson, John W; Chase, P Bryant

    2014-10-01

    The digital flexors of horses must produce high force to support the body weight during running, and a need for these muscles to generate power is likely limited during locomotion over level ground. Measurements of power output from horse muscle fibers close to physiological temperatures, and when cyclic strain is imposed, will help to better understand the in vivo performance of the muscles as power absorbers and generators. Skinned fibers from the deep (DDF) and superficial (SDF) digital flexors, and the soleus (SOL) underwent sinusoidal oscillations in length over a range of frequencies (0.5-16 Hz) and strain amplitudes (0.01-0.06) under maximum activation (pCa 5) at 30°C. Results were analyzed using both workloop and Nyquist plot analyses to determine the ability of the fibers to absorb or generate power and the frequency dependence of those abilities. Power absorption was dominant at most cycling frequencies and strain amplitudes in fibers from all three muscles. However, small amounts of power were generated (0.002-0.05 Wkg(-1)) at 0.01 strain by all three muscles at relatively slow cycling frequencies: DDF (4-7 Hz), SDF (4-5 Hz) and SOL (0.5-1 Hz). Nyquist analysis, reflecting the influence of cross-bridge kinetics on power generation, corroborated these results. The similar capacity for power generation by DDF and SDF versus lower for SOL, and the faster frequency at which this power was realized in DDF and SDF fibers, are largely explained by the fast myosin heavy chain isoform content in each muscle. Contractile function of DDF and SDF as power absorbers and generators, respectively, during locomotion may therefore be more dependent on their fiber architectural arrangement than on the physiological properties of their muscle fibers. PMID:25293602

  20. Effects of Gestational and Postnatal Exposure to Chronic Intermittent Hypoxia on Diaphragm Muscle Contractile Function in the Rat

    PubMed Central

    McDonald, Fiona B.; Dempsey, Eugene M.; O'Halloran, Ken D.

    2016-01-01

    Alterations to the supply of oxygen during early life presents a profound stressor to physiological systems with aberrant remodeling that is often long-lasting. Chronic intermittent hypoxia (CIH) is a feature of apnea of prematurity, chronic lung disease, and sleep apnea. CIH affects respiratory control but there is a dearth of information concerning the effects of CIH on respiratory muscles, including the diaphragm—the major pump muscle of breathing. We investigated the effects of exposure to gestational CIH (gCIH) and postnatal CIH (pCIH) on diaphragm muscle function in male and female rats. CIH consisted of exposure in environmental chambers to 90 s of hypoxia reaching 5% O2 at nadir, once every 5 min, 8 h a day. Exposure to gCIH started within 24 h of identification of a copulation plug and continued until day 20 of gestation; animals were studied on postnatal day 22 or 42. For pCIH, pups were born in normoxia and within 24 h of delivery were exposed with dams to CIH for 3 weeks; animals were studied on postnatal day 22 or 42. Sham groups were exposed to normoxia in parallel. Following gas exposures, diaphragm muscle contractile, and endurance properties were examined ex vivo. Neither gCIH nor pCIH exposure had effects on diaphragm muscle force-generating capacity or endurance in either sex. Similarly, early life exposure to CIH did not affect muscle tolerance of severe hypoxic stress determined ex vivo. The findings contrast with our recent observation of upper airway dilator muscle weakness following exposure to pCIH. Thus, the present study suggests a relative resilience to hypoxic stress in diaphragm muscle. Co-ordinated activity of thoracic pump and upper airway dilator muscles is required for optimal control of upper airway caliber. A mismatch in the force-generating capacity of the complementary muscle groups could have adverse consequences for the control of airway patency and respiratory homeostasis. PMID:27462274

  1. Effects of Gestational and Postnatal Exposure to Chronic Intermittent Hypoxia on Diaphragm Muscle Contractile Function in the Rat.

    PubMed

    McDonald, Fiona B; Dempsey, Eugene M; O'Halloran, Ken D

    2016-01-01

    Alterations to the supply of oxygen during early life presents a profound stressor to physiological systems with aberrant remodeling that is often long-lasting. Chronic intermittent hypoxia (CIH) is a feature of apnea of prematurity, chronic lung disease, and sleep apnea. CIH affects respiratory control but there is a dearth of information concerning the effects of CIH on respiratory muscles, including the diaphragm-the major pump muscle of breathing. We investigated the effects of exposure to gestational CIH (gCIH) and postnatal CIH (pCIH) on diaphragm muscle function in male and female rats. CIH consisted of exposure in environmental chambers to 90 s of hypoxia reaching 5% O2 at nadir, once every 5 min, 8 h a day. Exposure to gCIH started within 24 h of identification of a copulation plug and continued until day 20 of gestation; animals were studied on postnatal day 22 or 42. For pCIH, pups were born in normoxia and within 24 h of delivery were exposed with dams to CIH for 3 weeks; animals were studied on postnatal day 22 or 42. Sham groups were exposed to normoxia in parallel. Following gas exposures, diaphragm muscle contractile, and endurance properties were examined ex vivo. Neither gCIH nor pCIH exposure had effects on diaphragm muscle force-generating capacity or endurance in either sex. Similarly, early life exposure to CIH did not affect muscle tolerance of severe hypoxic stress determined ex vivo. The findings contrast with our recent observation of upper airway dilator muscle weakness following exposure to pCIH. Thus, the present study suggests a relative resilience to hypoxic stress in diaphragm muscle. Co-ordinated activity of thoracic pump and upper airway dilator muscles is required for optimal control of upper airway caliber. A mismatch in the force-generating capacity of the complementary muscle groups could have adverse consequences for the control of airway patency and respiratory homeostasis. PMID:27462274

  2. Frequency dependence of power and its implications for contractile function of muscle fibers from the digital flexors of horses

    PubMed Central

    Butcher, Michael T.; Bertram, John E.A.; Syme, Douglas A.; Hermanson, John W.; Chase, P. Bryant

    2014-01-01

    Abstract The digital flexors of horses must produce high force to support the body weight during running, and a need for these muscles to generate power is likely limited during locomotion over level ground. Measurements of power output from horse muscle fibers close to physiological temperatures, and when cyclic strain is imposed, will help to better understand the in vivo performance of the muscles as power absorbers and generators. Skinned fibers from the deep (DDF) and superficial (SDF) digital flexors, and the soleus (SOL) underwent sinusoidal oscillations in length over a range of frequencies (0.5–16 Hz) and strain amplitudes (0.01–0.06) under maximum activation (pCa 5) at 30°C. Results were analyzed using both workloop and Nyquist plot analyses to determine the ability of the fibers to absorb or generate power and the frequency dependence of those abilities. Power absorption was dominant at most cycling frequencies and strain amplitudes in fibers from all three muscles. However, small amounts of power were generated (0.002–0.05 Wkg−1) at 0.01 strain by all three muscles at relatively slow cycling frequencies: DDF (4–7 Hz), SDF (4–5 Hz) and SOL (0.5–1 Hz). Nyquist analysis, reflecting the influence of cross‐bridge kinetics on power generation, corroborated these results. The similar capacity for power generation by DDF and SDF versus lower for SOL, and the faster frequency at which this power was realized in DDF and SDF fibers, are largely explained by the fast myosin heavy chain isoform content in each muscle. Contractile function of DDF and SDF as power absorbers and generators, respectively, during locomotion may therefore be more dependent on their fiber architectural arrangement than on the physiological properties of their muscle fibers. PMID:25293602

  3. Effects of silver ions (Ag+) on contractile ring function and microtubule dynamics during first cleavage in Ilyanassa obsoleta

    NASA Technical Reports Server (NTRS)

    Conrad, A. H.; Stephens, A. P.; Paulsen, A. Q.; Schwarting, S. S.; Conrad, G. W.; Spooner, B. S. (Principal Investigator)

    1994-01-01

    The terminal phase of cell division involves tight constriction of the cleavage furrow contractile ring, stabilization/elongation of the intercellular bridge, and final separation of the daughter cells. At first cleavage, the fertilized eggs of the mollusk, Ilyanassa obsoleta, form two contractile rings at right angles to each other in the same cytoplasm that constrict to tight necks and partition the egg into a trefoil shape. The cleavage furrow contractile ring (CF) normally constricts around many midbody microtubules (MTs) and results in cleavage; the polar lobe constriction contractile ring (PLC) normally constricts around very few MTs and subsequently relaxes without cleavage. In the presence of Ag+ ions, the PLC 1) begins MT-dependent rapid constriction sooner than controls, 2) encircles more MTs than control egg PLCs, 3) elongates much more than control PLCs, and 4) remains tightly constricted and effectively cleaves the polar lobe from the egg. If Ag(+)-incubated eggs are returned to normal seawater at trefoil, tubulin fluorescence disappears from the PLC neck and the neck relaxes. If nocodazole, a drug that depolymerizes MTs, is added to Ag(+)-incubated eggs during early PLC constriction, the PLC is not stabilized and eventually relaxes. However, if nocodazole is added to Ag(+)-incubated eggs at trefoil, tubulin fluorescence disappears from the PLC neck but the neck remains constricted. These results suggest that Ag+ accelerates and gradually stabilizes the PLC constriction by a mechanism that is initially MT-dependent, but that progressively becomes MT-independent.

  4. Asymmetric Expression of Connexins between luminal epithelial- and myoepithelial- cells is Essential for Contractile Function of the Mammary Gland

    PubMed Central

    Mroue, Rana; Inman, Jamie; Mott, Joni; Budunova, Irina; Bissell, Mina J.

    2016-01-01

    myoepithelial cells, highlighting the importance of cell type-specific expression of Cxs for optimal contractile function of the mammary myoepithelium. PMID:25500615

  5. Hibernating myocardium retains metabolic and contractile reserve despite regional reductions in flow, function, and oxygen consumption at rest.

    PubMed

    Fallavollita, James A; Malm, Brian J; Canty, John M

    2003-01-10

    Hibernating myocardium, characterized by reductions in flow and function at rest, has limited contractile reserve in response to increases in external workload. We hypothesized that this attenuation of function reflects an adaptive downregulation that prevents the development of metabolic evidence of ischemia during stress. To test this hypothesis, pigs were chronically instrumented with a proximal left anterior descending artery stenosis for 3 months, resulting in severe anteroapical hypokinesis with reduced resting perfusion (0.78+/-0.05 versus 0.94+/-0.07 mL x min(-1)x g(-1) in remote, P<0.01; and 0.99+/-0.08 in controls, P<0.05). Open-chest studies confirmed resting dysfunction compared with normal controls (segment shortening 9.2+/-2.2% versus 23.5+/-1.1%, P<0.05). Resting myocardial oxygen consumption was reduced (63+/-3 versus 77+/-6 microL x g(-1) x min(-1) in controls, P<0.05), yet lactate consumption was normal. Although subendocardial perfusion failed to increase during graded, intravenous epinephrine infusion (n=8), peak segment shortening (to 17.3+/-3.1%, P<0.05) and oxygen consumption (to 90+/-6 microL x g(-1) x min(-1), P<0.01) increased from the depressed resting levels. There was no lactate production in hibernating myocardium, and lactate uptake increased during stress (0.7+/-0.1 to 1.2+/-0.1 micromol x g(-1) x min(-1), P<0.05). The absence of metabolic evidence of ischemia was also confirmed during atrial pacing to a rate of 120 bpm (n=8). Thus, despite reductions in function and oxygen consumption at rest, hibernating myocardium retains the ability to increase metabolism without the development of acute ischemia. This supports the hypothesis that the downregulation of oxygen consumption and function in hibernating myocardium is an adaptive response that prevents a supply-demand imbalance during submaximal increases in cardiac workload when coronary flow reserve is limited. PMID:12522120

  6. Selective TNF-α targeting with infliximab attenuates impaired oxygen metabolism and contractile function induced by an acute exposure to air particulate matter.

    PubMed

    Marchini, Timoteo; D'Annunzio, Verónica; Paz, Mariela L; Cáceres, Lourdes; Garcés, Mariana; Perez, Virginia; Tasat, Deborah; Vanasco, Virginia; Magnani, Natalia; Gonzalez Maglio, Daniel; Gelpi, Ricardo J; Alvarez, Silvia; Evelson, Pablo

    2015-11-15

    Inflammation plays a central role in the onset and progression of cardiovascular diseases associated with the exposure to air pollution particulate matter (PM). The aim of this work was to analyze the cardioprotective effect of selective TNF-α targeting with a blocking anti-TNF-α antibody (infliximab) in an in vivo mice model of acute exposure to residual oil fly ash (ROFA). Female Swiss mice received an intraperitoneal injection of infliximab (10 mg/kg body wt) or saline solution, and were intranasally instilled with a ROFA suspension (1 mg/kg body wt). Control animals were instilled with saline solution and handled in parallel. After 3 h, heart O2 consumption was assessed by high-resolution respirometry in left ventricle tissue cubes and isolated mitochondria, and ventricular contractile reserve and lusitropic reserve were evaluated according to the Langendorff technique. ROFA instillation induced a significant decrease in tissue O2 consumption and active mitochondrial respiration by 32 and 31%, respectively, compared with the control group. While ventricular contractile state and isovolumic relaxation were not altered in ROFA-exposed mice, impaired contractile reserve and lusitropic reserve were observed in this group. Infliximab pretreatment significantly attenuated the decrease in heart O2 consumption and prevented the decrease in ventricular contractile and lusitropic reserve in ROFA-exposed mice. Moreover, infliximab-pretreated ROFA-exposed mice showed conserved left ventricular developed pressure and cardiac O2 consumption in response to a β-adrenergic stimulus with isoproterenol. These results provides direct evidence linking systemic inflammation and altered cardiac function following an acute exposure to PM and contribute to the understanding of PM-associated cardiovascular morbidity and mortality. PMID:26386109

  7. Muscle disuse alters skeletal muscle contractile function at the molecular and cellular levels in older adult humans in a sex-specific manner

    PubMed Central

    Callahan, Damien M; Miller, Mark S; Sweeny, Andrew P; Tourville, Timothy W; Slauterbeck, James R; Savage, Patrick D; Maugan, David W; Ades, Philip A; Beynnon, Bruce D; Toth, Michael J

    2014-01-01

    Physical inactivity that accompanies ageing and disease may hasten disability by reducing skeletal muscle contractility. To characterize skeletal muscle functional adaptations to muscle disuse, we compared contractile performance at the molecular, cellular and whole-muscle levels in healthy active older men and women (n = 15) and inactive older men and women with advanced-stage, symptomatic knee osteoarthritis (OA) (n = 16). OA patients showed reduced (P < 0.01) knee extensor function. At the cellular level, single muscle fibre force production was reduced in OA patients in myosin heavy chain (MHC) I and IIA fibres (both P < 0.05) and differences in IIA fibres persisted after adjustments for fibre cross-sectional area (P < 0.05). Although no group differences in contractile velocity or power output were found for any fibre type, sex was found to modify the effect of OA, with a reduction in MHC IIA power output and a trend towards reduced shortening velocity in women, but increases in both variables in men (P < 0.05 and P = 0.07, respectively). At the molecular level, these adaptations in MHC IIA fibre function were explained by sex-specific differences (P ≤ 0.05) in myosin–actin cross-bridge kinetics. Additionally, cross-bridge kinetics were slowed in MHC I fibres in OA patients (P < 0.01), attributable entirely to reductions in women with knee OA (P < 0.05), a phenotype that could be reproduced in vitro by chemical modification of protein thiol residues. Our results identify molecular and cellular functional adaptations in skeletal muscle that may contribute to reduced physical function with knee OA-associated muscle disuse, with sex-specific differences that may explain a greater disposition towards disability in women. PMID:25038243

  8. Intravenous Followed by X-ray Fused with MRI-Guided Transendocardial Mesenchymal Stem Cell Injection Improves Contractility Reserve in a Swine Model of Myocardial Infarction

    PubMed Central

    Schmuck, Eric G.; Koch, Jill M.; Hacker, Timothy A.; Hatt, Charles R.; Tomkowiak, Michael T.; Vigen, Karl K.; Hendren, Nicholas; Leitzke, Cathlyn; Zhao, Ying-qi; Li, Zhanhai; Centanni, John M.; Hei, Derek J.; Schwahn, Denise; Kim, Jaehyup; Hematti, Peiman

    2016-01-01

    The aim of this study is to determine the effects of early intravenous (IV) infusion later followed by transendocardial (TE) injection of allogeneic mesenchymal stem cells (MSCs) following myocardial infarction (MI). Twenty-four swine underwent balloon occlusion reperfusion MI and were randomized into 4 groups: IV MSC (or placebo) infusion (post-MI day 2) and TE MSC (or placebo) injection targeting the infarct border with 2D X-ray fluoroscopy fused to 3D magnetic resonance (XFM) co-registration (post-MI day 14). Continuous ECG recording, MRI, and invasive pressure-volume analyses were performed. IV MSC plus TE MSC treated group was superior to other groups for contractility reserve (p=0.02) and freedom from VT (p=0.03) but had more lymphocytic foci localized to the peri-infarct region (p= 0.002). No differences were observed in post-MI remodeling parameters. IV followed by XFM targeted TE MSC therapy improves contractility reserve and suppresses VT but does not affect post-MI remodeling and may cause an immune response. PMID:26374144

  9. Intravenous Followed by X-ray Fused with MRI-Guided Transendocardial Mesenchymal Stem Cell Injection Improves Contractility Reserve in a Swine Model of Myocardial Infarction.

    PubMed

    Schmuck, Eric G; Koch, Jill M; Hacker, Timothy A; Hatt, Charles R; Tomkowiak, Michael T; Vigen, Karl K; Hendren, Nicholas; Leitzke, Cathlyn; Zhao, Ying-Qi; Li, Zhanhai; Centanni, John M; Hei, Derek J; Schwahn, Denise; Kim, Jaehyup; Hematti, Peiman; Raval, Amish N

    2015-10-01

    The aim of this study is to determine the effects of early intravenous (IV) infusion later followed by transendocardial (TE) injection of allogeneic mesenchymal stem cells (MSCs) following myocardial infarction (MI). Twenty-four swine underwent balloon occlusion reperfusion MI and were randomized into 4 groups: IV MSC (or placebo) infusion (post-MI day 2) and TE MSC (or placebo) injection targeting the infarct border with 2D X-ray fluoroscopy fused to 3D magnetic resonance (XFM) co-registration (post-MI day 14). Continuous ECG recording, MRI, and invasive pressure-volume analyses were performed. IV MSC plus TE MSC treated group was superior to other groups for contractility reserve (p = 0.02) and freedom from VT (p = 0.03) but had more lymphocytic foci localized to the peri-infarct region (p = 0.002). No differences were observed in post-MI remodeling parameters. IV followed by XFM targeted TE MSC therapy improves contractility reserve and suppresses VT but does not affect post-MI remodeling and may cause an immune response. PMID:26374144

  10. Functional alterations in gut contractility after connexin36 ablation and evidence for gap junctions forming electrical synapses between nitrergic enteric neurons

    PubMed Central

    Nagy, James Imre; Urena-Ramirez, Viridiana; Ghia, Jean-Eric

    2014-01-01

    Neurons in the enteric nervous system utilize numerous neurotransmitters to orchestrate rhythmic gut smooth muscle contractions. We examined whether electrical synapses formed by gap junctions containing connexin36 also contribute to communication between enteric neurons in mouse colon. Spontaneous contractility properties and responses to electrical field stimulation and cholinergic agonist were altered in gut from connexin36 knockout vs. wild-type mice. Immunofluorescence revealed punctate labelling of connexin36 that was localized at appositions between somata of enteric neurons immunopositive for the enzyme nitric oxide synthase. There is indication for a possible functional role of gap junctions between inhibitory nitrergic enteric neurons. PMID:24548563

  11. [The cardioprotective action of the anticonvulsant preparation sodium valproate in disorders of cardiac contractile function caused by acute myocardial infarct in rats].

    PubMed

    Belkina, L M; Korchazhkina, N B; Kamskova, Iu G; Fomin, N A

    1997-01-01

    The preventive and therapeutical effects of sodium valproate (SV), 200 mg/kg, on cardiac contractile disorders (developed pressure, rate-pressure products, dp/dt) were studied in rats having 2-day myocardial infarction (MI). The postinfarction rather than preinfarction use of SV substantially restricted the depressed resting left ventricular function. Given by two regimens, SV increased cardiac resistance to the maximum isometric load induced by 60-sec ligation of the ascending aorta. The cardioprotective effect of the drug was shown due to its positive chronotropic action rather than its inotropic one. Thus, SV may be used as an effective drug for the prevention and treatment of postinfarct cardiac dysfunctions. PMID:9235532

  12. Effect of lead on cholinergic contractile function in the forestomach, ileum and colon of the male Wistar rat

    SciTech Connect

    Ryden, E.B.

    1986-01-01

    Gastrointestinal symptoms, including colic, are signs of lead poisoning in man, but the mechanism of these effects has not been elucidated. In order to understand the effects of lead on acetylcholine (ACh)-mediated responses, studies were undertaken to determine the isometric contractile response to methacholine, KCl and electric field stimulation in rat forestomach, ileum and colon under conditions of in vitro and in vivo treatment with lead acetate. Rats were dosed with 4% lead acetate in their diet, NIH-07, for 7 weeks, which resulted in renal and hematologic toxicity and blood lead levels of 180-389 ug/dl (1.2 x 10/sup -5/ M). Tissues from in vivo treated rats were exposed to 1.2 x 10/sup -5/ M lead acetate during in vitro contractile studies. E/sub max/ or ED/sub 50/ methacholine was not affected by 1.2 x 10/sup -5/ M lead acetate, administered in vitro to control tissue. In the forestomach, a 10-fold higher concentration of lead (16 x 10/sup -5/ M), administered in vitro, increased baseline tension and inhibition response to methacholine. However, in vivo lead treatment potentiated response to methacholine in the forestomach and increased baseline tension in the presence of physostigmine. The EFS response, attributable to ACh release, was not affected in the forestomach or ileum by 1.2 x 10/sup -5/ M in vitro lead treatment. These data indicate that lead, administered in vivo in concentrations which cause renal and hematologic toxicity, does not impair cholinergic contractile response in gastrointestinal smooth muscle. Instead, the response to methacholine may be potentiated in the forestomach. Possible mechanisms of lead-induced potentiation of baseline or evoked tension include increased levels of non-elicited ACh release, inhibition of acetylcholinesterase or sensitization of muscarinic receptors.

  13. Action of ouabain and an amino-cardenolide on Na/sup +/-pump function and contractility of isolated canine heart cells

    SciTech Connect

    Porterfield, L.M.; Songu-Mize, E.; Chryssanthis, T.; Caldwell, R.W.

    1986-03-05

    Viable, rod-shaped, Ca/sup + +/-tolerant cells were isolated from the cardiac ventricle of adult mongrel dogs, a digitalis-sensitive species. These cells do not contract spontaneously but contractions were driven by electrical field stimulation. Changes in contractile amplitude were assessed by computer-assisted analysis of recorded phase contrast images. Addition of a polar aminocardenolide (AC), ASI-222, produced a dose-related increase in contractility with a concentration producing a 50% maximal response (RC/sub 50/) of 4 x 10/sup -8/M. For ouabain (OB) the RC/sub 50/ was 7 x 10/sup -7/M. Cellular Na/sup +/-pump (NaP) function was determined as digitalis-sensitive /sup 86/Rb/sup +/-uptake. Addition of AC and OB to these cells produced a dose-related decrease in /sup 86/Rb/sup +/-uptake; concentrations which produced a 50% inhibition (IC/sub 50/) of NaP function were of 6 x 10/sup -8/M and 1.2 x 10/sup -6/M for AC and OB, respectively. Their data indicates that in isolated dog heart cells AC is both a more potent inotropic agent and an inhibitor of NaP function by 15-20 fold than OB. The RC/sub 50/ and IC/sub 50/ for these processes correlate for each glycoside.

  14. Restoring redox balance enhances contractility in heart trabeculae from type 2 diabetic rats exposed to high glucose

    PubMed Central

    Bhatt, Niraj M.; Aon, Miguel A.; Tocchetti, Carlo G.; Shen, Xiaoxu; Dey, Swati; Ramirez-Correa, Genaro; O′Rourke, Brian; Gao, Wei Dong

    2014-01-01

    Hearts from type 2 diabetic (T2DM) subjects are chronically subjected to hyperglycemia and hyperlipidemia, both thought to contribute to oxidizing conditions and contractile dysfunction. How redox alterations and contractility interrelate, ultimately diminishing T2DM heart function, remains poorly understood. Herein we tested whether the fatty acid palmitate (Palm), in addition to its energetic contribution, rescues function by improving redox [glutathione (GSH), NAD(P)H, less oxidative stress] in T2DM rat heart trabeculae subjected to high glucose. Using cardiac trabeculae from Zucker Diabetic Fatty (ZDF) rats, we assessed the impact of low glucose (EG) and high glucose (HG), in absence or presence of Palm or insulin, on force development, energetics, and redox responses. We found that in EG ZDF and lean trabeculae displayed similar contractile work, yield of contractile work (Ycw), representing the ratio of force time integral over rate of O2 consumption. Conversely, HG had a negative impact on Ycw, whereas Palm, but not insulin, completely prevented contractile loss. This effect was associated with higher GSH, less oxidative stress, and augmented matrix GSH/thioredoxin (Trx) in ZDF mitochondria. Restoration of myocardial redox with GSH ethyl ester also rescued ZDF contractile function in HG, independently from Palm. These results support the idea that maintained redox balance, via increased GSH and Trx antioxidant activities to resist oxidative stress, is an essential protective response of the diabetic heart to keep contractile function. PMID:25485897

  15. Passive heating following the prematch warm-up in soccer: examining the time-course of changes in muscle temperature and contractile function.

    PubMed

    Marshall, Paul W M; Cross, Rebecca; Lovell, Ric

    2015-12-01

    This study examined changes in muscle temperature, electrically evoked muscle contractile properties, and voluntary power before and after a soccer specific active warm-up and subsequent rest period. Ten amateur soccer players performed two experimental sessions that involved performance of a modified FIFA 11+ soccer specific warm-up, followed by a 12.5-min rest period where participants were required to wear either normal clothing or a passive electrical heating garment was applied to the upper thigh muscles. Assessments around the warm-up and cool-down included measures of maximal torque, rate of torque development, muscle temperature (Tm), and electrically evoked measures of quadriceps contractile function. Tm was increased after the warm-up by 3.2 ± 0.7°C (P < 0.001). Voluntary and evoked rates of torque development increased after the warm-up between 20% and 30% (P < 0.05), despite declines in both maximal voluntary torque and voluntary activation (P < 0.05). Application of a passive heating garment in the cool-down period after the warm-up did not effect variables measured. While Tm was reduced by 1.4 ± 0.4°C after the rest period (P < 0.001), this value was still higher than pre warm-up levels. Voluntary and evoked rate of torque development remained elevated from pre warm-up levels at the end of the cool-down (P < 0.05). The soccer specific warm-up elevated muscle temperature by 3.2°C and was associated with concomitant increases of between 20% and 30% in voluntary rate of torque development, which seems explained by elevations in rate-dependent measures of intrinsic muscle contractile function. Application of a passive heating garment did not attenuate declines in muscle temperature during a 12.5-min rest period. PMID:26634901

  16. Mechanochemical actuators of embryonic epithelial contractility.

    PubMed

    Kim, YongTae; Hazar, Melis; Vijayraghavan, Deepthi S; Song, Jiho; Jackson, Timothy R; Joshi, Sagar D; Messner, William C; Davidson, Lance A; LeDuc, Philip R

    2014-10-01

    Spatiotemporal regulation of cell contractility coordinates cell shape change to construct tissue architecture and ultimately directs the morphology and function of the organism. Here we show that contractility responses to spatially and temporally controlled chemical stimuli depend much more strongly on intercellular mechanical connections than on biochemical cues in both stimulated tissues and adjacent cells. We investigate how the cell contractility is triggered within an embryonic epithelial sheet by local ligand stimulation and coordinates a long-range contraction response. Our custom microfluidic control system allows spatiotemporally controlled stimulation with extracellular ATP, which results in locally distinct contractility followed by mechanical strain pattern formation. The stimulation-response circuit exposed here provides a better understanding of how morphogenetic processes integrate responses to stimulation and how intercellular responses are transmitted across multiple cells. These findings may enable one to create a biological actuator that actively drives morphogenesis. PMID:25246549

  17. Maternal Nutrient Restriction Alters Ca2+ Handling Properties and Contractile Function of Isolated Left Ventricle Bundles in Male But Not Female Juvenile Rats

    PubMed Central

    Murphy, Robyn M.; Morrison, Janna L.

    2015-01-01

    Intrauterine growth restriction (IUGR), defined as a birth weight below the 10th centile, may be caused by maternal undernutrition, with evidence that IUGR offspring have an increased risk of cardiovascular disease (CVD) in adulthood. Calcium ions (Ca2+) are an integral messenger for several steps associated with excitation-contraction coupling (ECC); the cascade of events from the initiation of an action potential at the surface membrane, to contraction of the cardiomyocyte. Any changes in Ca2+ storage and release from the sarcoplasmic reticulum (SR), or sensitivity of the contractile apparatus to Ca2+ may underlie the mechanism linking IUGR to an increased risk of CVD. This study aimed to explore the effects of maternal nutrient restriction on cardiac function, including Ca2+ handling by the SR and force development by the contractile apparatus. Juvenile Long Evans hooded rats born to Control (C) and nutrient restricted (NR) dams were anaesthetized for collection of the heart at 10–12 weeks of age. Left ventricular bundles from male NR offspring displayed increased maximum Ca2+-activated force, and decreased protein content of troponin I (cTnI) compared to C males. Furthermore, male NR offspring showed a reduction in rate of rise of the caffeine-induced Ca2+ force response and a decrease in the protein content of ryanodine receptor (RYR2). These physiological and biochemical findings observed in males were not evident in female offspring. These findings illustrate a sex-specific effect of maternal NR on cardiac development, and also highlight a possible mechanism for the development of hypertension and hypertrophy in male NR offspring. PMID:26406887

  18. Cardiac Contractility Modulation in a Model of Repaired Tetralogy of Fallot: A Sheep Model.

    PubMed

    Roubertie, Francois; Eschalier, Romain; Zemmoura, Adlane; Thambo, Jean-Benoit; Rooryck, Caroline; Labrousse, Louis; Ploux, Sylvain; Ritter, Philippe; Haïssaguerre, Michel; Dos Santos, Pierre; Bordachar, Pierre

    2016-06-01

    The onset of right ventricular dysfunction in patients presenting with congenital heart disease is associated with a dismal long-term outcome and often represents a therapeutic dead end. Our study had several objectives: (1) to analyse the anatomical, functional, histological and cellular characteristics of an animal model of repaired tetralogy of Fallot with right ventricular dysfunction (2) to test the new electrical treatment known as cardiac contractility modulation in this animal model. Seven sheep underwent a first surgery at the age of three weeks aiming to mimic the characteristics of a repaired tetralogy of Fallot. Five controls were sham-operated. Experimental studies were performed 12 months after the initial operation. The hemodynamic, echocardiographic, and mitochondrial function studies were carried out before and after cardiac contractility modulation in closed- and open-chest conditions. In this animal model of right ventricular dysfunction, short-term cardiac contractility modulation was associated with a significant improvement in (a) right ventricular function, as evidenced by a significant increase in right ventricular dP/dt (p < 0.05) (b) left ventricular function evidenced by the increase in left ventricular dP/dt max (p < 0.05) (c) in mitochondrial function (p < 0.05). In this animal model of chronic right ventricular dysfunction, cardiac contractility modulation significantly improved acute cardiac hemodynamic and mitochondrial functions of both ventricles and may represent a promising option in patients with right heart failure. PMID:27126593

  19. Human ES- and iPS-Derived Myogenic Progenitors Restore Dystrophin and Improve Contractility upon Transplantation in Dystrophic Mice

    PubMed Central

    Darabi, Radbod; Arpke, Robert W.; Irion, Stefan; Dimos, John T.; Grskovic, Marica; Kyba, Michael; Perlingeiro, Rita C. R.

    2012-01-01

    SUMMARY A major obstacle in the application of cell-based therapies for the treatment of neuromuscular disorders is obtaining the appropriate number of stem/progenitor cells to produce effective engraftment. The use of embryonic stem (ES) or induced pluripotent stem (iPS) cells could overcome this hurdle. However to date, derivation of engraftable skeletal muscle precursors that can restore muscle function from human pluripotent cells has not been achieved. Here we applied conditional expression of Pax7 in human ES/iPS cells to successfully derive large quantities of myogenic precursors, which upon transplantation into dystrophic muscle, are able to engraft efficiently, producing abundant human-derived dystrophin-positive myofibers that exhibit superior strength. Importantly, transplanted cells also seed the muscle satellite cell compartment and engraftment is present over 11 months post-transplant. This study provides the proof-of-principle for the derivation of functional skeletal myogenic progenitors from human ES/iPS cells, and highlights their potential for future therapeutic application in muscular dystrophies. PMID:22560081

  20. [NO-DEPENDENT MECHANISM OF THE CARDIOPROTECTIVE ACTION OF PHENIBUT ON STRESS-INDUCED VIOLATION OF CONTRACTILE FUNCTION OF THE HEART].

    PubMed

    Tyurenkov, I N; Perfilova, V N; Sadikova, N V; Prokofiev, I I

    2015-01-01

    A stressor action for 24 h reduces both ino- and chronotropic reserves of animal heart as evidenced by a decrease in rate growth increments of contraction and relaxation of the myocardium, left ventricular pressure (LVP), heart rate, and the maximum intensity of functioning (MIF) as compared to intact animals during testing for adrenoreactivity and maximum isometric load caused by clamping of the ascending part of the aortic arch. Blockade of NO-synthase leads to a high percentage of animal death during the stressor action, anesthesia, opening of the chest, and functional tests and causes marked reduction in the growth rates of contraction (+dP/dt max) and relaxation (-dP/dt max) speed, LVP, heart rate, and MIF--on the average about 2 times (p < 0.05) under load testing conditions as compared to a control group of stressed animals. Phenibut limits stress-induced violations of the myocardium contractility, as indicated by a higher growth of performance in stress tests--on the average about 1.8 times (p < 0.05) in comparison to the control group of animals. The cardioprotective effect of phenibut is less pronounced when it is introduced on the background of the blockade of NO-ergic system. Under these conditions, there are cases of animal death, predominantly during the stressor action. The results obtained suggest that, for ensuring cardioprotective action of phenibut under conditions of stress-induced myocardial damage, it is necessary to provide for participation of nitric oxide system. PMID:27017698

  1. Functional engineered human cardiac patches prepared from nature's platform improve heart function after acute myocardial infarction.

    PubMed

    Wang, Qingjie; Yang, Hui; Bai, Aobing; Jiang, Wei; Li, Xiuya; Wang, Xinhong; Mao, Yishen; Lu, Chao; Qian, Ruizhe; Guo, Feng; Ding, Tianling; Chen, Haiyan; Chen, Sifeng; Zhang, Jianyi; Liu, Chen; Sun, Ning

    2016-10-01

    With the advent of induced pluripotent stem cells and directed differentiation techniques, it is now feasible to derive individual-specific cardiac cells for human heart tissue engineering. Here we report the generation of functional engineered human cardiac patches using human induced pluripotent stem cells-derived cardiac cells and decellularized natural heart ECM as scaffolds. The engineered human cardiac patches can be tailored to any desired size and shape and exhibited normal contractile and electrical physiology in vitro. Further, when patching on the infarct area, these patches improved heart function of rats with acute myocardial infarction in vivo. These engineered human cardiac patches can be of great value for normal and disease-specific heart tissue engineering, drug screening, and meet the demands for individual-specific heart tissues for personalized regenerative therapy of myocardial damages in the future. PMID:27509303

  2. Investigation into the cardiotoxic effects of doxorubicin on contractile function and the protection afforded by cyclosporin A using the work-loop assay.

    PubMed

    Gharanei, Mayel; Hussain, Afthab; James, Rob S; Janneh, Omar; Maddock, Helen

    2014-08-01

    Doxorubicin is known to cause cardiotoxicity through multiple routes including the build-up of reactive oxygen species and disruption of the calcium homeostasis in cardiac myocytes, but the effect of drug treatment on the associated biomechanics of cardiac injury remains unclear. Detecting and understanding the adverse effects of drugs on cardiac contractility is becoming a priority in non-clinical safety pharmacology assessment. The work-loop technique enables the assessment of force-length work-loop contractions, which mimic those of the pressure-volume work-loops experienced by the heart in vivo. During this study we evaluated whether the work-loop technique could potentially provide improved insight into the biomechanics associated with drug-induced cardiac dysfunction. In order to do this we investigated the cardiotoxic effects of doxorubicin and characterised the protection afforded by the co-administration of cyclosporin A (CsA). This study provides detailed biomechanical in vitro insight into the cardiac dysfunction associated with Doxorubicin treatment, including reduction in peak force, force during shortening and power output. These effects were significantly abrogated in doxorubicin-CsA co-treatment studies. Closely mimicking the in vivo pressure-volume muscle mechanics, this assay provides a quick and easy technique to gain a better understanding of the detailed biomechanics of drug-induced cardiac dysfunction. PMID:24509045

  3. Abnormal calcium homeostasis in heart failure with preserved ejection fraction is related to both reduced contractile function and incomplete relaxation: an electromechanically detailed biophysical modeling study

    PubMed Central

    Adeniran, Ismail; MacIver, David H.; Hancox, Jules C.; Zhang, Henggui

    2015-01-01

    Heart failure with preserved ejection fraction (HFpEF) accounts for about 50% of heart failure cases. It has features of incomplete relaxation and increased stiffness of the left ventricle. Studies from clinical electrophysiology and animal experiments have found that HFpEF is associated with impaired calcium homeostasis, ion channel remodeling and concentric left ventricle hypertrophy (LVH). However, it is still unclear how the abnormal calcium homeostasis, ion channel and structural remodeling affect the electro-mechanical dynamics of the ventricles. In this study we have developed multiscale models of the human left ventricle from single cells to the 3D organ, which take into consideration HFpEF-induced changes in calcium handling, ion channel remodeling and concentric LVH. Our simulation results suggest that at the cellular level, HFpEF reduces the systolic calcium level resulting in a reduced systolic contractile force, but elevates the diastolic calcium level resulting in an abnormal residual diastolic force. In our simulations, these abnormal electro-mechanical features of the ventricular cells became more pronounced with the increase of the heart rate. However, at the 3D organ level, the ejection fraction of the left ventricle was maintained due to the concentric LVH. The simulation results of this study mirror clinically observed features of HFpEF and provide new insights toward the understanding of the cellular bases of impaired cardiac electromechanical functions in heart failure. PMID:25852567

  4. Surgical Treatment of Concomitant Atrial Fibrillation: Focus onto Atrial Contractility

    PubMed Central

    Loardi, Claudia; Alamanni, Francesco; Galli, Claudia; Naliato, Moreno; Veglia, Fabrizio; Zanobini, Marco; Pepi, Mauro

    2015-01-01

    Background. Maze procedure aims at restoring sinus rhythm (SR) and atrial contractility (AC). This study evaluated multiple aspects of AC recovery and their relationship with SR regain after ablation. Methods. 122 mitral and fibrillating patients underwent radiofrequency Maze. Rhythm check and echocardiographic control of biatrial contractility were performed at 3, 6, 12, and 24 months postoperatively. A multivariate Cox analysis of risk factors for absence of AC recuperation was applied. Results. At 2-years follow-up, SR was achieved in 79% of patients. SR-AC coexistence increased from 76% until 98%, while biatrial contraction detection augmented from 84 to 98% at late stage. Shorter preoperative arrhythmia duration was the only common predictor of SR-AC restoring, while pulmonary artery pressure (PAP) negatively influenced AC recuperation. Early AC restoration favored future freedom from arrhythmia recurrence. Minor LA dimensions correlated with improved future A/E value and vice versa. Right atrial (RA) contractility restoring favored better left ventricular (LV) performance and volumes. Conclusions. SR and left AC are two interrelated Maze objectives. Factors associated with arrhythmia “chronic state” (PAP and arrhythmia duration) are negative predictors of procedural success. Our results suggest an association between postoperative LA dimensions and “kick” restoring and an influence of RA contraction onto LV function. PMID:26229956

  5. Effects of nicotine on rat sternohyoid muscle contractile properties.

    PubMed

    O'Halloran, Ken D

    2006-02-28

    Obstructive sleep apnoea (OSA) is a major clinical disorder characterised by recurring episodes of pharyngeal collapse during sleep. At present, there remains no satisfactory treatment for OSA. Pharmacological therapies as a potential treatment for the disorder are an attractive option and include agents that increase the contractility of the pharyngeal muscles. The aim of the present study was to examine the effects of nicotine on upper airway muscle contractile properties. In vitro isometric contractile properties were determined using strips of rat sternohyoid muscle in physiological salt solution containing nicotine (0-100 microg/ml) at 25 degrees C. Isometric twitch and tetanic tension, contraction time, half-relaxation time and tension-frequency relationship were determined by electrical field stimulation with platinum electrodes. Fatigue was induced by stimulation at 40 Hz with 300 ms trains at a frequency of 0.5 Hz for 5 min. Nicotine at a concentration of 1 microg/ml was associated with a significant increase in sternohyoid muscle specific tension compared to control data. Dose-dependent increases in contractile tension were not observed. Nicotine had effects on tension-frequency relationship and endurance properties of the sternohyoid muscle at some but not all doses. A leftward shift in the tension-frequency relationship was observed at low stimulus frequencies (20-30 Hz) for nicotine at a concentration of 1 and 5 microg/ml and a significant increase in fatigue resistance was observed with nicotine at a concentration of 10 microg/ml. As fatigue of the upper airway muscles has been implicated in obstructive airway conditions, a pharmacological agent that improves muscle endurance may prove useful as a potential treatment for such disorders. Therefore, further studies of the effects of nicotinic agonists on upper airway function are warranted. PMID:15994135

  6. Effects of neuronal nitric oxide synthase inhibition on microvascular and contractile function in skeletal muscle of aged rats

    PubMed Central

    Hirai, Daniel M.; Copp, Steven W.; Holdsworth, Clark T.; Ferguson, Scott K.; Musch, Timothy I.

    2012-01-01

    Advanced age is associated with derangements in skeletal muscle microvascular function during the transition from rest to contractions. We tested the hypothesis that, contrary to what was reported previously in young rats, selective neuronal nitric oxide (NO) synthase (nNOS) inhibition would result in attenuated or absent alterations in skeletal muscle microvascular oxygenation (Po2mv), which reflects the matching between muscle O2 delivery and utilization, following the onset of contractions in old rats. Spinotrapezius muscle blood flow (radiolabeled microspheres), Po2mv (phosphorescence quenching), O2 utilization (V̇o2; Fick calculation), and submaximal force production were measured at rest and following the onset of contractions in anesthetized old male Fischer 344 × Brown Norway rats (27 to 28 mo) pre- and postselective nNOS inhibition (2.1 μmol/kg S-methyl-l-thiocitrulline; SMTC). At rest, SMTC had no effects on muscle blood flow (P > 0.05) but reduced V̇o2 by ∼23% (P < 0.05), which elevated basal Po2mv by ∼18% (P < 0.05). During contractions, steady-state muscle blood flow, V̇o2, Po2mv, and force production were not altered after SMTC (P > 0.05 for all). The overall Po2mv dynamics following onset of contractions was also unaffected by SMTC (mean response time: pre, 19.7 ± 1.5; and post, 20.0 ± 2.0 s; P > 0.05). These results indicate that the locus of nNOS-derived NO control in skeletal muscle depends on age and metabolic rate (i.e., rest vs. contractions). Alterations in nNOS-mediated regulation of contracting skeletal muscle microvascular function with aging may contribute to poor exercise capacity in this population. PMID:22923618

  7. Implication of advanced glycation end products (Ages) and their receptor (Rage) on myocardial contractile and mitochondrial functions.

    PubMed

    Neviere, Remi; Yu, Yichi; Wang, Lei; Tessier, Frederic; Boulanger, Eric

    2016-08-01

    Advanced glycation end products (AGEs) play an important role for the development and/or progression of cardiovascular diseases, mainly through induction of oxidative stress and inflammation. AGEs are a heterogeneous group of molecules formed by non-enzymatic reaction of reducing sugars with amino acids of proteins, lipids and nucleic acids. AGEs are mainly formed endogenously, while recent studies suggest that diet constitutes an important exogenous source of AGEs. The presence and accumulation of AGEs in various cardiac cell types affect extracellular and intracellular structure and function. AGEs contribute to a variety of microvascular and macrovascular complications through the formation of cross-links between molecules in the basement membrane of the extracellular matrix and by engaging the receptor for advanced glycation end products (RAGE). Activation of RAGE by AGEs causes up regulation of the transcription factor nuclear factor-κB and its target genes. of the RAGE engagement stimulates oxidative stress, evokes inflammatory and fibrotic reactions, which all contribute to the development and progression of devastating cardiovascular disorders. This review discusses potential targets of glycation in cardiac cells, and underlying mechanisms that lead to heart failure with special interest on AGE-induced mitochondrial dysfunction in the myocardium. PMID:27277623

  8. Altered energy state reversibly controls smooth muscle contractile function in human saphenous vein during acute hypoxia-reoxygenation: Role of glycogen, AMP-activated protein kinase, and insulin-independent glucose uptake.

    PubMed

    Pyla, Rajkumar; Pichavaram, Prahalathan; Fairaq, Arwa; Park, Mary Anne; Kozak, Mark; Kamath, Vinayak; Patel, Vijay S; Segar, Lakshman

    2015-09-01

    Hypoxia is known to promote vasodilation of coronary vessels through several mediators including cardiac-derived adenosine and endothelium-derived prostanoids and nitric oxide. To date, the impact of endogenous glycogen depletion in vascular smooth muscle and the resultant alterations in cellular energy state (e.g., AMP-activated protein kinase, AMPK) on the contractile response to G protein-coupled receptor agonists (e.g., serotonin, 5-HT) has not yet been studied. In the present study, ex vivo exposure of endothelium-denuded human saphenous vein rings to hypoxic and glucose-deprived conditions during KCl-induced contractions for 30 min resulted in a marked depletion of endogenous glycogen by ∼80% (from ∼1.78 μmol/g under normoxia to ∼0.36 μmol/g under hypoxia). Importantly, glycogen-depleted HSV rings, which were maintained under hypoxia/reoxygenation and glucose-deprived conditions, exhibited significant increases in basal AMPK phosphorylation (∼6-fold ↑) and 5-HT-induced AMPK phosphorylation (∼19-fold ↑) with an accompanying suppression of 5-HT-induced maximal contractile response (∼68% ↓), compared with respective controls. Exposure of glycogen-depleted HSV rings to exogenous D-glucose, but not the inactive glucose analogs, prevented the exaggerated increase in 5-HT-induced AMPK phosphorylation and restored 5-HT-induced maximal contractile response. In addition, the ability of exogenous D-glucose to rescue cellular stress and impaired contractile function occurred through GLUT1-mediated but insulin/GLUT4-independent mechanisms. Together, the present findings from clinically-relevant human saphenous vein suggest that the loss of endogenous glycogen in vascular smooth muscle and the resultant accentuation of AMPK phosphorylation by GPCR agonists may constitute a yet another mechanism of metabolic vasodilation of coronary vessels in ischemic heart disease. PMID:26212549

  9. Cell Density and Joint microRNA-133a and microRNA-696 Inhibition Enhance Differentiation and Contractile Function of Engineered Human Skeletal Muscle Tissues.

    PubMed

    Cheng, Cindy S; Ran, Lydia; Bursac, Nenad; Kraus, William E; Truskey, George A

    2016-04-01

    To utilize three-dimensional (3D) engineered human skeletal muscle tissue for translational studies and in vitro studies of drug toxicity, there is a need to promote differentiation and functional behavior. In this study, we identified conditions to promote contraction of engineered human skeletal muscle bundles and examined the effects of transient inhibition of microRNAs (miRs) on myogenic differentiation and function of two-dimensional (2D) and 3D cultures of human myotubes. In 2D cultures, simultaneously inhibiting both miR-133a, which promotes myoblast proliferation, and miR-696, which represses oxidative metabolism, resulted in an increase in sarcomeric α-actinin protein and the metabolic coactivator PGC-1α protein compared to transfection with a scrambled miR sequence (negative control). Although PGC-1α was elevated following joint inhibition of miRs 133a and 696, there was no difference in myosin heavy chain (MHC) protein isoforms. 3D engineered human skeletal muscle myobundles seeded with 5 × 10(6) human skeletal myoblasts (HSkM)/mL and cultured for 2 weeks after onset of differentiation consistently did not contract when stimulated electrically, whereas those seeded with myoblasts at 10 × 10(6) HSkM/mL or higher did contract. When HSkM were transfected with both anti-miRs and seeded into fibrin hydrogels and cultured for 2 weeks under static conditions, twitch and tetanic specific forces after electrical stimulation were greater than for myobundles prepared with HSkM transfected with scrambled sequences. Immunofluorescence and Western blots of 3D myobundles indicate that anti-miR-133a or anti-miR-696 treatment led to modest increases in slow MHC, but no consistent increase in fast MHC. Similar to results in 2D, only myobundles prepared with myoblasts treated with anti-miR-133a and anti-miR-696 produced an increase in PGC-1α mRNA. PGC-1α targets were differentially affected by the treatment. HIF-2α mRNA showed an expression pattern similar

  10. Cardiac Function Is Regulated by B56α-mediated Targeting of Protein Phosphatase 2A (PP2A) to Contractile Relevant Substrates*

    PubMed Central

    Kirchhefer, Uwe; Brekle, Christiane; Eskandar, John; Isensee, Gunnar; Kučerová, Dana; Müller, Frank U.; Pinet, Florence; Schulte, Jan S.; Seidl, Matthias D.; Boknik, Peter

    2014-01-01

    Dephosphorylation of important myocardial proteins is regulated by protein phosphatase 2A (PP2A), representing a heterotrimer that is comprised of catalytic, scaffolding, and regulatory (B) subunits. There is a multitude of B subunit family members directing the PP2A holoenzyme to different myocellular compartments. To gain a better understanding of how these B subunits contribute to the regulation of cardiac performance, we generated transgenic (TG) mice with cardiomyocyte-directed overexpression of B56α, a phosphoprotein of the PP2A-B56 family. The 2-fold overexpression of B56α was associated with an enhanced PP2A activity that was localized mainly in the cytoplasm and myofilament fraction. Contractility was enhanced both at the whole heart level and in isolated cardiomyocytes of TG compared with WT mice. However, peak amplitude of [Ca]i did not differ between TG and WT cardiomyocytes. The basal phosphorylation of cardiac troponin inhibitor (cTnI) and the myosin-binding protein C was reduced by 26 and 35%, respectively, in TG compared with WT hearts. The stimulation of β-adrenergic receptors by isoproterenol (ISO) resulted in an impaired contractile response of TG hearts. At a depolarizing potential of −5 mV, the ICa,L current density was decreased by 28% after administration of ISO in TG cardiomyocytes. In addition, the ISO-stimulated phosphorylation of phospholamban at Ser16 was reduced by 27% in TG hearts. Thus, the increased PP2A-B56α activity in TG hearts is localized to specific subcellular sites leading to the dephosphorylation of important contractile proteins. This may result in higher myofilament Ca2+ sensitivity and increased basal contractility in TG hearts. These effects were reversed by β-adrenergic stimulation. PMID:25320082

  11. Muscarinic Receptor Activation Affects Pulmonary Artery Contractility in Sheep: The Impact of Maturation and Chronic Hypoxia on Endothelium-Dependent and Endothelium-Independent Function.

    PubMed

    Giang, Michael; Papamatheakis, Demosthenes G; Nguyen, Dan; Paez, Ricardo; Blum Johnston, Carla; Kim, Joon; Brunnell, Alexander; Blood, Quintin; Goyal, Ravi; Longo, Lawrence D; Wilson, Sean M

    2016-06-01

    Giang, Michael, Demosthenes G. Papamatheakis, Dan Nguyen, Ricardo Paez, Carla Blum Johnston, Joon Kim, Alexander Brunnell, Quintin Blood, Ravi Goyal, Lawrence D. Longo, and Sean M. Wilson. Muscarinic receptor activation affects pulmonary artery contractility in sheep: the impact of maturation and chronic hypoxia on endothelium-dependent and endothelium-independent function. High Alt Med Biol. 17:122-132, 2015.-Muscarinic receptor activation in the pulmonary vasculature can cause endothelium-dependent vasodilation and smooth muscle-dependent vasoconstriction. Chronic hypoxia (CH) can modify both of these responses. This study aimed to assess the combined influence of CH and maturation on endothelium-dependent and endothelium-independent muscarinic-induced vasoreactivity. This was accomplished by performing wire myography on endothelium-intact or endothelium-disrupted pulmonary arterial rings isolated from normoxic or CH fetal and adult sheep. In endothelium-intact arteries, vasodilation was evaluated using cumulative bradykinin doses in phenylephrine and carbachol precontracted pulmonary arterial segments; and vasoconstriction was examined using cumulative doses of carbachol following bradykinin predilation. Effects of nonselective (atropine) and selective M1 (pirenzepine), M2 (AFDX116), and M3 (4-DAMP and Dau5884) muscarinic receptor antagonists were assessed in disrupted arteries. In normoxic arteries, bradykinin relaxation was twofold greater in the adult compared to fetus, while carbachol contraction was fourfold greater. In adult arteries, CH increased bradykinin relaxation and carbachol contraction. In vessels with intact endothelium, maturation and CH augmented maximal response and efficacy for carbachol constriction and bradykinin relaxation. Approximately 50%-80% of adult normoxic and CH endothelium-disrupted arteries contracted to acetylcholine, while ∼50% of fetal normoxic and ∼10% of CH arteries responded. Atropine reduced carbachol

  12. Optimum periodicity of repeated contractile actions applied in mass transport

    NASA Astrophysics Data System (ADS)

    Ahn, Sungsook; Lee, Sang Joon

    2015-01-01

    Dynamically repeated periodic patterns are abundant in natural and artificial systems, such as tides, heart beats, stock prices, and the like. The characteristic repeatability and periodicity are expected to be optimized in effective system-specific functions. In this study, such optimum periodicity is experimentally evaluated in terms of effective mass transport using one-valve and multi-valve systems working in contractile fluid flows. A set of nanoscale gating functions is utilized, operating in nanocomposite networks through which permeates selectively pass under characteristic contractile actions. Optimized contractile periodicity exists for effective energy impartment to flow in a one-valve system. In the sequential contractile actions for a multi-valve system, synchronization with the fluid flow is critical for effective mass transport. This study provides fundamental understanding on the various repeated periodic patterns and dynamic repeatability occurring in nature and mechanical systems, which are useful for broad applications.

  13. Optimum periodicity of repeated contractile actions applied in mass transport

    PubMed Central

    Ahn, Sungsook; Lee, Sang Joon

    2015-01-01

    Dynamically repeated periodic patterns are abundant in natural and artificial systems, such as tides, heart beats, stock prices, and the like. The characteristic repeatability and periodicity are expected to be optimized in effective system-specific functions. In this study, such optimum periodicity is experimentally evaluated in terms of effective mass transport using one-valve and multi-valve systems working in contractile fluid flows. A set of nanoscale gating functions is utilized, operating in nanocomposite networks through which permeates selectively pass under characteristic contractile actions. Optimized contractile periodicity exists for effective energy impartment to flow in a one-valve system. In the sequential contractile actions for a multi-valve system, synchronization with the fluid flow is critical for effective mass transport. This study provides fundamental understanding on the various repeated periodic patterns and dynamic repeatability occurring in nature and mechanical systems, which are useful for broad applications. PMID:25622949

  14. Spontaneous actin dynamics in contractile rings

    NASA Astrophysics Data System (ADS)

    Kruse, Karsten; Wollrab, Viktoria; Thiagarajan, Raghavan; Wald, Anne; Riveline, Daniel

    Networks of polymerizing actin filaments are known to be capable to self-organize into a variety of structures. For example, spontaneous actin polymerization waves have been observed in living cells in a number of circumstances, notably, in crawling neutrophils and slime molds. During later stages of cell division, they can also spontaneously form a contractile ring that will eventually cleave the cell into two daughter cells. We present a framework for describing networks of polymerizing actin filaments, where assembly is regulated by various proteins. It can also include the effects of molecular motors. We show that the molecular processes driven by these proteins can generate various structures that have been observed in contractile rings of fission yeast and mammalian cells. We discuss a possible functional role of each of these patterns. The work was supported by Agence Nationale de la Recherche, France, (ANR-10-LABX-0030-INRT) and by Deutsche Forschungsgemeinschaft through SFB1027.

  15. Actomyosin contractility rotates the cell nucleus

    PubMed Central

    Kumar, Abhishek; Maitra, Ananyo; Sumit, Madhuresh; Ramaswamy, Sriram; Shivashankar, G. V.

    2014-01-01

    The cell nucleus functions amidst active cytoskeletal filaments, but its response to their contractile stresses is largely unexplored. We study the dynamics of the nuclei of single fibroblasts, with cell migration suppressed by plating onto micro-fabricated patterns. We find the nucleus undergoes noisy but coherent rotational motion. We account for this observation through a hydrodynamic approach, treating the nucleus as a highly viscous inclusion residing in a less viscous fluid of orientable filaments endowed with active stresses. Lowering actin contractility selectively by introducing blebbistatin at low concentrations drastically reduced the speed and coherence of the angular motion of the nucleus. Time-lapse imaging of actin revealed a correlated hydrodynamic flow around the nucleus, with profile and magnitude consistent with the results of our theoretical approach. Coherent intracellular flows and consequent nuclear rotation thus appear to be an intrinsic property of cells. PMID:24445418

  16. ATP-independent contractile proteins from plants

    NASA Astrophysics Data System (ADS)

    Knoblauch, Michael; Noll, Gundula A.; Müller, Torsten; Prüfer, Dirk; Schneider-Hüther, Ingrid; Scharner, Dörte; van Bel, Aart J. E.; Peters, Winfried S.

    2003-09-01

    Emerging technologies are creating increasing interest in smart materials that may serve as actuators in micro- and nanodevices. Mechanically active polymers currently studied include a variety of materials. ATP-driven motor proteins, the actuators of living cells, possess promising characteristics, but their dependence on strictly defined chemical environments can be disadvantagous. Natural proteins that deform reversibly by entropic mechanisms might serve as models for artificial contractile polypeptides with useful functionality, but they are rare. Protein bodies from sieve elements of higher plants provide a novel example. sieve elements form microfluidics systems for pressure-driven transport of photo-assimilates throughout the plant. Unique protein bodies in the sieve elements of legumes act as cellular stopcocks, by undergoing a Ca2+-dependent conformational switch in which they plug the sieve element. In living cells, this reaction is probably controlled by Ca2+-transporters in the cell membrane. Here we report the rapid, reversible, anisotropic and ATP-independent contractility in these protein bodies in vitro. Considering the unique biological function of the legume 'crystalloid' protein bodies and their contractile properties, we suggest to give them the distinctive name forisome ('gate-body'; from the Latin foris, the wing of a gate).

  17. Maternal Age and Contractility of Human Myometrium in Pregnancy.

    PubMed

    Crankshaw, Denis J; O'Brien, Yvonne M; Crosby, David A; Morrison, John J

    2015-10-01

    There is controversy as to whether maternal age exerts an influence on the contractility of human myometrium in pregnancy. The aim of this study was to examine a series of functional contractile parameters of human myometrium in vitro, over a broad range of maternal ages. Myometrial tissue specimens were obtained at cesarean delivery from 32 women with maternal ages ranging from 28 to 52 years. Using in vitro recordings, a number of contractile parameters including maximal amplitude, mean contractile force, time to maximal amplitude, maximum rate of rise, and occurrence of simple and complex (biphasic and multiphasic) contractions were examined for spontaneous and induced contractile activity. The relationship between maternal age and individual parameters was evaluated using linear regression analysis. For all contractile parameters examined, for both spontaneous and induced contractions, no significant correlation was observed with maternal age between 28 and 52 years. The mean maximum amplitude values for spontaneous and oxytocin-induced contractions were 23 ± 3 and 43 ± 5 mN, respectively. The mean contractile forces for spontaneous and oxytocin-induced contractions were 1.5 ± 0.2 and 6.5 ± 0.9 mN, respectively. There was no variation in the proportion of biphasic or multiphasic contractions with maternal age. These results indicate there is no significant functional impairment of uterine contractility and no lack in responsiveness of myometrium in vitro, in the older mother. These findings do not support the concept that there may be a biological basis for dysfunctional labor or increased cesarean delivery rates in older parturients. PMID:25759369

  18. Chinese Herbal Medicine Treatment Improves the Overall Survival Rate of Individuals with Hypertension among Type 2 Diabetes Patients and Modulates In Vitro Smooth Muscle Cell Contractility.

    PubMed

    Lin, Ying-Ju; Ho, Tsung-Jung; Yeh, Yi-Chun; Cheng, Chi-Fung; Shiao, Yi-Tzone; Wang, Chang-Bi; Chien, Wen-Kuei; Chen, Jin-Hua; Liu, Xiang; Tsang, Hsinyi; Lin, Ting-Hsu; Liao, Chiu-Chu; Huang, Shao-Mei; Li, Ju-Pi; Lin, Cheng-Wen; Pang, Hao-Yu; Lin, Jaung-Geng; Lan, Yu-Ching; Liu, Yu-Huei; Chen, Shih-Yin; Tsai, Fuu-Jen; Liang, Wen-Miin

    2015-01-01

    Type 2 diabetes (T2D) is a chronic, multifactorial, and metabolic disorder accounting for 90% diabetes cases worldwide. Among them, almost half of T2D have hypertension, which is responsible for cardiovascular disease, morbidity, and mortality in these patients. The Chinese herbal medicine (CHM) prescription patterns of hypertension individuals among T2D patients have yet to be characterized. This study, therefore, aimed to determine their prescription patterns and evaluate the CHM effect. A cohort of one million randomly sampled cases from the National Health Insurance Research Database (NHIRD) was used to investigate the overall survival rate of CHM users, and prescription patterns. After matching CHM and non-CHM users for age, gender and date of diagnosis of hypertension, 980 subjects for each group were selected. The CHM users were characterized with slightly longer duration time from diabetes to hypertension, and more cases for hyperlipidaemia. The cumulative survival probabilities were higher in CHM users than in non-CHM users. Among these top 12 herbs, Liu-Wei-Di-Huang-Wan, Jia-Wei-Xiao-Yao-San, Dan-Shen, and Ge-Gen were the most common herbs and inhibited in vitro smooth muscle cell contractility. Our study also provides a CHM comprehensive list that may be useful in future investigation of the safety and efficacy for individuals with hypertension among type 2 diabetes patients. PMID:26699542

  19. Chinese Herbal Medicine Treatment Improves the Overall Survival Rate of Individuals with Hypertension among Type 2 Diabetes Patients and Modulates In Vitro Smooth Muscle Cell Contractility

    PubMed Central

    Yeh, Yi-Chun; Cheng, Chi-Fung; Shiao, Yi-Tzone; Wang, Chang-Bi; Chien, Wen-Kuei; Chen, Jin-Hua; Liu, Xiang; Tsang, Hsinyi; Lin, Ting-Hsu; Liao, Chiu-Chu; Huang, Shao-Mei; Li, Ju-Pi; Lin, Cheng-Wen; Pang, Hao-Yu; Lin, Jaung-Geng; Lan, Yu-Ching; Liu, Yu-Huei; Chen, Shih-Yin; Tsai, Fuu-Jen; Liang, Wen-Miin

    2015-01-01

    Type 2 diabetes (T2D) is a chronic, multifactorial, and metabolic disorder accounting for 90% diabetes cases worldwide. Among them, almost half of T2D have hypertension, which is responsible for cardiovascular disease, morbidity, and mortality in these patients. The Chinese herbal medicine (CHM) prescription patterns of hypertension individuals among T2D patients have yet to be characterized. This study, therefore, aimed to determine their prescription patterns and evaluate the CHM effect. A cohort of one million randomly sampled cases from the National Health Insurance Research Database (NHIRD) was used to investigate the overall survival rate of CHM users, and prescription patterns. After matching CHM and non-CHM users for age, gender and date of diagnosis of hypertension, 980 subjects for each group were selected. The CHM users were characterized with slightly longer duration time from diabetes to hypertension, and more cases for hyperlipidaemia. The cumulative survival probabilities were higher in CHM users than in non-CHM users. Among these top 12 herbs, Liu-Wei-Di-Huang-Wan, Jia-Wei-Xiao-Yao-San, Dan-Shen, and Ge-Gen were the most common herbs and inhibited in vitro smooth muscle cell contractility. Our study also provides a CHM comprehensive list that may be useful in future investigation of the safety and efficacy for individuals with hypertension among type 2 diabetes patients. PMID:26699542

  20. Role of microtubules in the contractile dysfunction of hypertrophied myocardium

    NASA Technical Reports Server (NTRS)

    Zile, M. R.; Koide, M.; Sato, H.; Ishiguro, Y.; Conrad, C. H.; Buckley, J. M.; Morgan, J. P.; Cooper, G. 4th

    1999-01-01

    OBJECTIVES: We sought to determine whether the ameliorative effects of microtubule depolymerization on cellular contractile dysfunction in pressure overload cardiac hypertrophy apply at the tissue level. BACKGROUND: A selective and persistent increase in microtubule density causes decreased contractile function of cardiocytes from cats with hypertrophy produced by chronic right ventricular (RV) pressure overloading. Microtubule depolymerization by colchicine normalizes contractility in these isolated cardiocytes. However, whether these changes in cellular function might contribute to changes in function at the more highly integrated and complex cardiac tissue level was unknown. METHODS: Accordingly, RV papillary muscles were isolated from 25 cats with RV pressure overload hypertrophy induced by pulmonary artery banding (PAB) for 4 weeks and 25 control cats. Contractile state was measured using physiologically sequenced contractions before and 90 min after treatment with 10(-5) mol/liter colchicine. RESULTS: The PAB significantly increased RV systolic pressure and the RV weight/body weight ratio in PAB; it significantly decreased developed tension from 59+/-3 mN/mm2 in control to 25+/-4 mN/mm2 in PAB, shortening extent from 0.21+/-0.01 muscle lengths (ML) in control to 0.12+/-0.01 ML in PAB, and shortening rate from 1.12+/-0.07 ML/s in control to 0.55+/-0.03 ML/s in PAB. Indirect immunofluorescence confocal microscopy showed that PAB muscles had a selective increase in microtubule density and that colchicine caused complete microtubule depolymerization in both control and PAB papillary muscles. Microtubule depolymerization normalized myocardial contractility in papillary muscles of PAB cats but did not alter contractility in control muscles. CONCLUSIONS: Excess microtubule density, therefore, is equally important to both cellular and to myocardial contractile dysfunction caused by chronic, severe pressure-overload cardiac hypertrophy.

  1. Effect of exercise training and myocardial infarction on force development and contractile kinetics in isolated canine myocardium.

    PubMed

    Canan, Benjamin D; Haizlip, Kaylan M; Xu, Ying; Monasky, Michelle M; Hiranandani, Nitisha; Milani-Nejad, Nima; Varian, Kenneth D; Slabaugh, Jessica L; Schultz, Eric J; Fedorov, Vadim V; Billman, George E; Janssen, Paul M L

    2016-04-15

    It is well known that moderate exercise training elicits a small increase in ventricular mass (i.e., a physiological hypertrophy) that has many beneficial effects on overall cardiac health. It is also well known that, when a myocardial infarction damages part of the heart, the remaining myocardium remodels to compensate for the loss of viable functioning myocardium. The effects of exercise training, myocardial infarction (MI), and their interaction on the contractile performance of the myocardium itself remain largely to be determined. The present study investigated the contractile properties and kinetics of right ventricular myocardium isolated from sedentary and exercise trained (10-12 wk progressively increasing treadmill running, begun 4 wk after MI induction) dogs with and without a left ventricular myocardial infarction. Exercise training increased force development, whereas MI decreased force development that was not improved by exercise training. Contractile kinetics were significantly slower in the trained dogs, whereas this impact of training was less or no longer present after MI. Length-dependent activation, both evaluated on contractile force and kinetics, was similar in all four groups. The control exercise-trained group exhibited a more positive force-frequency relationship compared with the sedentary control group while both sedentary and trained post-MI dogs had a more negative relationship. Last, the impact of the β-adrenergic receptor agonist isoproterenol resulted in a similar increase in force and acceleration of contractile kinetics in all groups. Thus, exercise training increased developed force but slowed contractile kinetics in control (noninfarcted animals), actions that were attenuated or completely absent in post-MI dogs. PMID:26823341

  2. The contractile ring coordinates curvature-dependent septum assembly during fission yeast cytokinesis

    PubMed Central

    Zhou, Zhou; Munteanu, Emilia Laura; He, Jun; Ursell, Tristan; Bathe, Mark; Huang, Kerwyn Casey; Chang, Fred

    2015-01-01

    The functions of the actin-myosin–based contractile ring in cytokinesis remain to be elucidated. Recent findings show that in the fission yeast Schizosaccharomyces pombe, cleavage furrow ingression is driven by polymerization of cell wall fibers outside the plasma membrane, not by the contractile ring. Here we show that one function of the ring is to spatially coordinate septum cell wall assembly. We develop an improved method for live-cell imaging of the division apparatus by orienting the rod-shaped cells vertically using microfabricated wells. We observe that the septum hole and ring are circular and centered in wild-type cells and that in the absence of a functional ring, the septum continues to ingress but in a disorganized and asymmetric manner. By manipulating the cleavage furrow into different shapes, we show that the ring promotes local septum growth in a curvature-dependent manner, allowing even a misshapen septum to grow into a more regular shape. This curvature-dependent growth suggests a model in which contractile forces of the ring shape the septum cell wall by stimulating the cell wall machinery in a mechanosensitive manner. Mechanical regulation of the cell wall assembly may have general relevance to the morphogenesis of walled cells. PMID:25355954

  3. Enhanced acyl-CoA dehydrogenase activity is associated with improved mitochondrial and contractile function in heart failure

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Heart failure is associated with decreased myocardial fatty acid oxidation capacity and has been likened to energy starvation. Increased fatty acid availability results in an induction of genes promoting fatty acid oxidation. The aim of the present study was to investigate possible mechanisms by whi...

  4. Hormone replacement therapy improves contractile function and myonuclear organization of single muscle fibres from postmenopausal monozygotic female twin pairs

    PubMed Central

    Qaisar, Rizwan; Renaud, Guillaume; Hedstrom, Yvette; Pöllänen, Eija; Ronkainen, Paula; Kaprio, Jaakko; Alen, Markku; Sipilä, Sarianna; Artemenko, Konstantin; Bergquist, Jonas; Kovanen, Vuokko; Larsson, Lars

    2013-01-01

    Ageing is associated with a decline in muscle mass and strength leading to increased physical dependency in old age. Postmenopausal women experience a greater decline than men of similar age in parallel with the decrease in female sex steroid hormone production. We recruited six monozygous female twin pairs (55–59 years old) where only one twin pair was on hormone replacement therapy (HRT use = 7.8 ± 4.3 years) to investigate the association of HRT with the cytoplasmic volume supported by individual myonuclei (myonuclear domain (MND) size,) together with specific force at the single fibre level. HRT use was associated with a significantly smaller (∼27%; P < 0.05) mean MND size in muscle fibres expressing the type I but not the IIa myosin heavy chain (MyHC) isoform. In comparison to non-users, higher specific force was recorded in HRT users both in muscle fibres expressing type I (∼27%; P < 0.05) and type IIa (∼23%; P < 0.05) MyHC isoforms. These differences were fibre-type dependent, i.e. the higher specific force in fast-twitch muscle fibres was primarily caused by higher force per cross-bridge while slow-twitch fibres relied on both a higher number and force per cross-bridge. HRT use had no effect on fibre cross-sectional area (CSA), velocity of unloaded shortening (V0) and relative proportion of MyHC isoforms. In conclusion, HRT appears to have significant positive effects on both regulation of muscle contraction and myonuclei organization in postmenopausal women. PMID:23459759

  5. THE CONTRACTILE PROCESS IN THE CILIATE, STENTOR COERULEUS

    PubMed Central

    Huang, B.; Pitelka, D. R.

    1973-01-01

    The structural basis for the function of microtubules and filaments in cell body contractility in the ciliate Stentor coeruleus was investigated. Cells in the extended state were obtained for ultrastructural analysis by treatment before fixation with a solution containing 10 mM EGTA, 50–80 mM Tris, 3 mM MgSO4, 7.5 mM NH4Cl, 10 mM phosphate buffer (pH 7.1). The response of Stentor to changes in the divalent cation concentrations in this solution suggests that Ca+2 and Mg+2 are physiologically important in the regulation of ciliate contractility. The generation of motive force for changes in cell length in Stentor resides in two distinct longitudinal cortical fiber systems, the km fibers and myonemes. Cyclic changes in cell length are associated with (a) the relative sliding of parallel, overlapping microtubule ribbons in the km fibers, and (b) a distinct alteration in the structure of the contractile filaments constituting the myonemes. The microtubule and filament systems are distinguished functionally as antagonistic contractile elements. The development of motive force for cell extension is accomplished by active microtubule-to-microtubule sliding generated by specific intertubule bridges. Evidence is presented which suggests that active shortening of contractile filaments, reflected in a reversible structural transformation of dense 4-nm filaments to tubular 10–12-nm filaments, provides the basis for rapid cell contraction. PMID:4633444

  6. Contractile cell forces deform macroscopic cantilevers and quantify biomaterial performance.

    PubMed

    Allenstein, U; Mayr, S G; Zink, M

    2015-07-01

    Cells require adhesion to survive, proliferate and migrate, as well as for wound healing and many other functions. The strength of contractile cell forces on an underlying surface is a highly relevant quantity to measure the affinity of cells to a rigid surface with and without coating. Here we show with experimental and theoretical studies that these forces create surface stresses that are sufficient to induce measurable bending of macroscopic cantilevers. Since contractile forces are linked to the formation of focal contacts, results give information on adhesion promoting qualities and allow a comparison of very diverse materials. In exemplary studies, in vitro fibroblast adhesion on the magnetic shape memory alloy Fe-Pd and on the l-lysine derived plasma-functionalized polymer PPLL was determined. We show that cells on Fe-Pd are able to induce surface stresses three times as high as on pure titanium cantilevers. A further increase was observed for PPLL, where the contractile forces are four times higher than on the titanium reference. In addition, we performed finite element simulations on the beam bending to back up the calculation of contractile forces from cantilever bending under non-homogenous surface stress. Our findings consolidate the role of contractile forces as a meaningful measure of biomaterial performance. PMID:26027952

  7. Myocardial Function Improved by Electromagnetic Field Induction of Stress Protein hsp70

    PubMed Central

    George, Isaac; Geddis, Matthew S.; Lill, Zachary; Lin, Hana; Gomez, Teodoro; Blank, Martin; Oz, Mehmet C.; Goodman, Reba

    2011-01-01

    Studies on myocardial function have shown that hsp70, stimulated by an increase in temperature, leads to improved survival following ischemia reperfusion (I-R). Low frequency electromagnetic fields (EMF) also induce the stress protein hsp70, but without elevating temperature. We have examined the hemodynamic changes in concert with EMF preconditioning and the induction of hsp70 to determine whether improved myocardial function occurs following I-R injury in Sprague-Dawley rats. Animals were exposed to EMF (60Hz, 8µT) for 30 minutes prior to I-R. Ischemia was then induced by ligation of left anterior descending coronary artery (LAD) for 30 minutes, followed by 30 minutes of reperfusion. Blood and heart tissue levels for hsp70 taken at 10 minute intervals were determined by Western blot and RNA transcription by rtPCR. Significant upregulation of the HSP70 gene and increased hsp70 levels were measured in response to EMF pre-exposures. Invasive hemodynamics, as measured using a volume conductance catheter, demonstrated significant recovery of systolic contractile function after 30 minutes of reperfusion following EMF exposure. Additionally, isovolemic relaxation, a measure of ventricular diastolic function, was markedly improved in EMF-treated animals. In conclusion, noninvasive EMF induction of hsp70 preserved myocardial function and has the potential to improve tolerance to ischemic injury. PMID:18446816

  8. Ways to improve your correlation functions

    NASA Technical Reports Server (NTRS)

    Hamilton, A. J. S.

    1993-01-01

    This paper describes a number of ways to improve on the standard method for measuring the two-point correlation function of large scale structure in the Universe. Issues addressed are: (1) the problem of the mean density, and how to solve it; (2) how to estimate the uncertainty in a measured correlation function; (3) minimum variance pair weighting; (4) unbiased estimation of the selection function when magnitudes are discrete; and (5) analytic computation of angular integrals in background pair counts.

  9. Evaluating the potential role of nitric oxide as a mediator of hydrostatic edema mediated intestinal contractile dysfunction

    PubMed Central

    Shah, Shinil K.; Xue, Hasen; Jimenez, Fernando; Kots, Alexander Y.; Choi, Byung-Kwon; Uray, Karen S.; Walker, Peter A.; Moore-Olufemi, Stacey D.; Velez, Natalia; Stewart, Randolph H.; Laine, Glen A.; Cox, Charles S.

    2010-01-01

    Background Administration of L-nil, a selective inhibitor of inducible nitric oxide synthase (iNOS), improves ileus in an animal model of resuscitation induced intestinal edema. The purpose of this study was to elucidate the iNOS/nitric oxide (NO) signal transduction pathway in intestinal edema. Materials and Methods Male Sprague Dawley rats were divided into two groups; CONTROL and RESUS + VH (edema, 80cc/kg normal saline (resuscitation) with mesenteric venous hypertension). iNOS mRNA and protein, iNOS activity, NO tissue levels, soluble guanylyl cyclase (sGC) expression, and cyclic guanosine monophosphate (cGMP) levels were measured. As a functional endpoint, we evaluated intestinal contractile strength and frequency in L-nil treated animals. Results Edema was associated with increased iNOS mRNA and protein expression without subsequent increases in iNOS activity or tissue NO levels. There was no significant change in sGC expression or increase in cGMP induced by edema. Administration of L-nil did not decrease edema development or preserve contractile strength, but increased contractile frequency. Conclusion Hydrostatic intestinal edema is not associated with increased iNOS activity or tissue NO levels. Administration of L-nil in edema increases intestinal contractile frequency. This may represent a potential mechanism for the amelioration of ileus seen with the administration of L-nil. PMID:20605598

  10. Role of Mitochondrial fission and fusion in cardiomyocyte contractility

    PubMed Central

    Givvimani, S; Pushpakumar, SB; Metreveli, N; Veeranki, S; Kundu, S; Tyagi, SC

    2015-01-01

    Background Mitochondria constitute 30% of cell volume and are engaged in two dynamic processes called fusion and fission, regulated by Drp-1(Dynamin related protein) and mitofusin 2 (Mfn2). Previously, we showed that Drp-1 inhibition ameliorates cardiovascular dysfunction following pressure overload in aortic banding model and myocardial infarction. As dynamic organelles, mitochondria are capable of changing their morphology in response to stress. However, whether such changes can alter their function and in turn cellular function is unknown. Further, a direct role of fission and fusion in cardiomyocyte contractility has not yet been studied. In this study, we hypothesize that disrupted fission and fusion balance by increased Drp-1 and decreased Mfn2 expression in cardiomyocytes affect their contractility through alterations in the calcium and potassium concentrations. Methods To verify this, we used freshly isolated ventricular myocytes from wild type mouse and transfected them with either siRNA to Drp-1 or Mfn2. Myocyte contractility studies were performed by IonOptix using a myopacer. Intracellular calcium and potassium measurements were done using flow cytometry. Immunocytochemistry (ICC) was done to evaluate live cell mitochondria and its membrane potential. Protein expression was done by Western blot and Immunocytochemistry. Results We found that silencing mitochondrial fission increased the myocyte contractility, while fusion inhibition decreased contractility with simultaneous changes in calcium and potassium. Also, we observed that increase in fission prompted decrease in Serca-2a and increase in cytochrome c leading to mitophagy. Conclusion Our results suggested that regulating mitochondrial fission and fusion have direct effects on overall cardiomyocyte contractility and thus function. PMID:25841124

  11. Acute pergolide exposure stiffens engineered valve interstitial cell tissues and reduces contractility in vitro.

    PubMed

    Capulli, Andrew K; MacQueen, Luke A; O'Connor, Blakely B; Dauth, Stephanie; Parker, Kevin Kit

    2016-01-01

    Medications based on ergoline-derived dopamine and serotonin agonists are associated with off-target toxicities that include valvular heart disease (VHD). Reports of drug-induced VHD resulted in the withdrawal of appetite suppressants containing fenfluramine and phentermine from the US market in 1997 and pergolide, a Parkinson's disease medication, in 2007. Recent evidence suggests that serotonin receptor activity affected by these medications modulates cardiac valve interstitial cell activation and subsequent valvular remodeling, which can lead to cardiac valve fibrosis and dysfunction similar to that seen in carcinoid heart disease. Failure to identify these risks prior to market and continued use of similar drugs reaffirm the need to improve preclinical evaluation of drug-induced VHD. Here, we present two complimentary assays to measure stiffness and contractile stresses generated by engineered valvular tissues in vitro. As a case study, we measured the effects of acute (24 h) pergolide exposure to engineered porcine aortic valve interstitial cell (AVIC) tissues. Pergolide exposure led to increased tissue stiffness, but it decreased both basal and active contractile tone stresses generated by AVIC tissues. Pergolide exposure also disrupted AVIC tissue organization (i.e., tissue anisotropy), suggesting that the mechanical properties and contractile functionality of these tissues are governed by their ability to maintain their structure. We expect further use of these assays to identify off-target drug effects that alter the phenotypic balance of AVICs, disrupt their ability to maintain mechanical homeostasis, and lead to VHD. PMID:27174867

  12. Functional molecular markers for crop improvement.

    PubMed

    Kage, Udaykumar; Kumar, Arun; Dhokane, Dhananjay; Karre, Shailesh; Kushalappa, Ajjamada C

    2016-10-01

    A tremendous decline in cultivable land and resources and a huge increase in food demand calls for immediate attention to crop improvement. Though molecular plant breeding serves as a viable solution and is considered as "foundation for twenty-first century crop improvement", a major stumbling block for crop improvement is the availability of a limited functional gene pool for cereal crops. Advancement in the next generation sequencing (NGS) technologies integrated with tools like metabolomics, proteomics and association mapping studies have facilitated the identification of candidate genes, their allelic variants and opened new avenues to accelerate crop improvement through development and use of functional molecular markers (FMMs). The FMMs are developed from the sequence polymorphisms present within functional gene(s) which are associated with phenotypic trait variations. Since FMMs obviate the problems associated with random DNA markers, these are considered as "the holy grail" of plant breeders who employ targeted marker assisted selections (MAS) for crop improvement. This review article attempts to consider the current resources and novel methods such as metabolomics, proteomics and association studies for the identification of candidate genes and their validation through virus-induced gene silencing (VIGS) for the development of FMMs. A number of examples where the FMMs have been developed and used for the improvement of cereal crops for agronomic, food quality, disease resistance and abiotic stress tolerance traits have been considered. PMID:26171816

  13. Protective effects of anisodamine on cigarette smoke extract-induced airway smooth muscle cell proliferation and tracheal contractility

    SciTech Connect

    Xu, Guang-Ni; Yang, Kai; Xu, Zu-Peng; Zhu, Liang; Hou, Li-Na; Qi, Hong; Chen, Hong-Zhuan Cui, Yong-Yao

    2012-07-01

    Anisodamine, an antagonist of muscarinic acetylcholine receptors (mAChRs), has been used therapeutically to improve smooth muscle function, including microvascular, intestinal and airway spasms. Our previous studies have revealed that airway hyper-reactivity could be prevented by anisodamine. However, whether anisodamine prevents smoking-induced airway smooth muscle (ASM) cell proliferation remained unclear. In this study, a primary culture of rat ASM cells was used to evaluate an ASM phenotype through the ability of the cells to proliferate and express contractile proteins in response to cigarette smoke extract (CSE) and intervention of anisodamine. Our results showed that CSE resulted in an increase in cyclin D1 expression concomitant with the G0/G1-to-S phase transition, and high expression of M2 and M3. Functional studies showed that tracheal hyper-contractility accompanied contractile marker α-SMA high-expression. These changes, which occur only after CSE stimulation, were prevented and reversed by anisodamine, and CSE-induced cyclin D1 expression was significantly inhibited by anisodamine and the specific inhibitor U0126, BAY11-7082 and LY294002. Thus, we concluded that the protective and reversal effects and mechanism of anisodamine on CSE-induced events might involve, at least partially, the ERK, Akt and NF-κB signaling pathways associated with cyclin D1 via mAChRs. Our study validated that anisodamine intervention on ASM cells may contribute to anti-remodeling properties other than bronchodilation. -- Highlights: ► CSE induces tracheal cell proliferation, hyper-contractility and α-SMA expression. ► Anisodamine reverses CSE-induced tracheal hyper-contractility and cell proliferation. ► ERK, PI3K, and NF-κB pathways and cyclin D1 contribute to the reversal effect.

  14. Considerations for Contractile Electroactive Materials and Actuators

    SciTech Connect

    Lenore Rasmussen, David Schramm, Paul Rasmussen, Kevin Mullaly, Ras Labs, LLC, Intelligent Materials for Prosthetics & Automation, Lewis D. Meixler, Daniel Pearlman and Alice Kirk

    2011-05-23

    Ras Labs produces contractile electroactive polymer (EAP) based materials and actuators that bend, swell, ripple, and contract (new development) with low electric input. In addition, Ras Labs produces EAP materials that quickly contract and expand, repeatedly, by reversing the polarity of the electric input, which can be cycled. This phenomenon was explored using molecular modeling, followed by experimentation. Applied voltage step functions were also investigated. High voltage steps followed by low voltage steps produced a larger contraction followed by a smaller contraction. Actuator control by simply adjusting the electric input is extremely useful for biomimetic applications. Muscles are able to partially contract. If muscles could only completely contract, nobody could hold an egg, for example, without breaking it. A combination of high and low voltage step functions could produce gross motor function and fine manipulation within the same actuator unit. Plasma treated electrodes with various geometries were investigated as a means of providing for more durable actuation.

  15. Considerations for contractile electroactive materials and actuators

    NASA Astrophysics Data System (ADS)

    Rasmussen, Lenore; Schramm, David; Rasmussen, Paul; Mullally, Kevin; Meixler, Lewis D.; Pearlman, Daniel; Kirk, Alice

    2011-04-01

    Ras Labs produces contractile electroactive polymer (EAP) based materials and actuators that bend, swell, ripple, and contract (new development) with low electric input. In addition, Ras Labs produces EAP materials that quickly contract and expand, repeatedly, by reversing the polarity of the electric input, which can be cycled. This phenomenon was explored using molecular modeling, followed by experimentation. Applied voltage step functions were also investigated. High voltage steps followed by low voltage steps produced a larger contraction followed by a smaller contraction. Actuator control by simply adjusting the electric input is extremely useful for biomimetic applications. Muscles are able to partially contract. If muscles could only completely contract, nobody could hold an egg, for example, without breaking it. A combination of high and low voltage step functions could produce gross motor function and fine manipulation within the same actuator unit. Plasma treated electrodes with various geometries were investigated as a means of providing for more durable actuation.

  16. Tricuspid annular plane systolic excursion and pulmonary arterial systolic pressure relationship in heart failure: an index of right ventricular contractile function and prognosis.

    PubMed

    Guazzi, M; Bandera, F; Pelissero, G; Castelvecchio, S; Menicanti, L; Ghio, S; Temporelli, P L; Arena, R

    2013-11-01

    Echo-derived pulmonary arterial systolic pressure (PASP) and right ventricular (RV) tricuspid annular plane systolic excursion (TAPSE; from the end of diastole to end-systole) are of basic relevance in the clinical follow-up of heart failure (HF) patients, carrying two- to threefold increase in cardiac risk when increased and reduced, respectively. We hypothesized that the relationship between TAPSE (longitudinal RV fiber shortening) and PASP (force generated by the RV) provides an index of in vivo RV length-force relationship, with their ratio better disclosing prognosis. Two hundred ninety-three HF patients with reduced (HFrEF, n = 247) or with preserved left ventricular (LV) ejection fraction (HFpEF, n = 46) underwent echo-Doppler studies and N-terminal pro-brain-type natriuretic peptide assessment and were tracked for adverse events. The median follow-up duration was 20.8 mo. TAPSE vs. PASP relationship showed a downward regression line shift in nonsurvivors who were more frequently presenting with higher PASP and lower TAPSE. HFrEF and HFpEF patients exhibited a similar distribution along the regression line. Given the TAPSE, PASP, and TAPSE-to-PASP ratio (TAPSE/PASP) collinearity, separate Cox regression and Kaplan-Meier analyses were performed: one with TAPSE and PASP as individual measures, and the other combining them in ratio form. Hazard ratios for variables retained in the multivariate regression were as follows: TAPSE/PASP functional class improves prognostic resolution. The TAPSE vs. PASP relationship as a possible index of the length-force relationship may be a step forward for a more efficient RV function evaluation and

  17. Does bariatric surgery improve adipose tissue function?

    PubMed

    Frikke-Schmidt, H; O'Rourke, R W; Lumeng, C N; Sandoval, D A; Seeley, R J

    2016-09-01

    Bariatric surgery is currently the most effective treatment for obesity. Not only do these types of surgeries produce significant weight loss but also they improve insulin sensitivity and whole body metabolic function. The aim of this review is to explore how altered physiology of adipose tissue may contribute to the potent metabolic effects of some of these procedures. This includes specific effects on various fat depots, the function of individual adipocytes and the interaction between adipose tissue and other key metabolic tissues. Besides a dramatic loss of fat mass, bariatric surgery shifts the distribution of fat from visceral to the subcutaneous compartment favoring metabolic improvement. The sensitivity towards lipolysis controlled by insulin and catecholamines is improved, adipokine secretion is altered and local adipose inflammation as well as systemic inflammatory markers decreases. Some of these changes have been shown to be weight loss independent, and novel hypothesis for these effects includes include changes in bile acid metabolism, gut microbiota and central regulation of metabolism. In conclusion bariatric surgery is capable of improving aspects of adipose tissue function and do so in some cases in ways that are not entirely explained by the potent effect of surgery. © 2016 World Obesity. PMID:27272117

  18. Effects of traumatic brain injury on intestinal contractility

    PubMed Central

    OLSEN, A. B.; HETZ, R. A.; XUE, H.; AROOM, K. R.; BHATTARAI, D.; JOHNSON, E.; BEDI, S.; COX, C. S.; URAY, K.

    2014-01-01

    Background Patients with traumatic brain injury (TBI) often suffer from gastrointestinal dysfunction including intolerance to enteral feedings. However, it is unclear how TBI affects small intestinal contractile activity. The purpose of this study was to determine if TBI affects intestinal smooth muscle function. Methods Sprague–Dawley rats were subjected to controlled cortical impact injury (TBI). Sham animals underwent a similar surgery but no injury (SHAM). Animals were sacrificed 1, 3, and 7 days after TBI and intestinal smooth muscle tissue was collected for measurement of contractile activity and transit, NF-kB activity, and cytokine levels. Brains were collected after sacrifice to determine volume loss due to injury. Key Results Contractile activity decreased significantly in ileum, but not jejunum, in the TBI group 7 days after injury compared with SHAM. Brain volume loss increased significantly 7 days after injury compared with 3 days and correlated significantly with the contractile activity 1 day after injury. In the intestinal smooth muscle, NF-kB activity increased significantly in the TBI group 3 and 7 days after injury vs SHAM. Wet to dry weight ratio, indicating edema, also increased significantly in the TBI group. Interleukin- 1α, -1β, and -17 increased significantly in the TBI group compared with SHAM. Conclusions & Inferences Traumatic brain injury causes a delayed but significant decrease in intestinal contractile activity in the ileum leading to delayed transit. The decreased intestinal contractile activity is attributed to secondary inflammatory injury as evidenced by increased NF-kB activity, increased edema, and increased inflammatory cytokines in the intestinal smooth muscle. PMID:23551971

  19. Nanowires and Electrical Stimulation Synergistically Improve Functions of hiPSC Cardiac Spheroids.

    PubMed

    Richards, Dylan J; Tan, Yu; Coyle, Robert; Li, Yang; Xu, Ruoyu; Yeung, Nelson; Parker, Arran; Menick, Donald R; Tian, Bozhi; Mei, Ying

    2016-07-13

    The advancement of human induced pluripotent stem-cell-derived cardiomyocyte (hiPSC-CM) technology has shown promising potential to provide a patient-specific, regenerative cell therapy strategy to treat cardiovascular disease. Despite the progress, the unspecific, underdeveloped phenotype of hiPSC-CMs has shown arrhythmogenic risk and limited functional improvements after transplantation. To address this, tissue engineering strategies have utilized both exogenous and endogenous stimuli to accelerate the development of hiPSC-CMs. Exogenous electrical stimulation provides a biomimetic pacemaker-like stimuli that has been shown to advance the electrical properties of tissue engineered cardiac constructs. Recently, we demonstrated that the incorporation of electrically conductive silicon nanowires to hiPSC cardiac spheroids led to advanced structural and functional development of hiPSC-CMs by improving the endogenous electrical microenvironment. Here, we reasoned that the enhanced endogenous electrical microenvironment of nanowired hiPSC cardiac spheroids would synergize with exogenous electrical stimulation to further advance the functional development of nanowired hiPSC cardiac spheroids. For the first time, we report that the combination of nanowires and electrical stimulation enhanced cell-cell junction formation, improved development of contractile machinery, and led to a significant decrease in the spontaneous beat rate of hiPSC cardiac spheroids. The advancements made here address critical challenges for the use of hiPSC-CMs in cardiac developmental and translational research and provide an advanced cell delivery vehicle for the next generation of cardiac repair. PMID:27328393

  20. Detecting cardiac contractile activity in the early mouse embryo using multiple modalities

    PubMed Central

    Chen, Chiann-Mun; Miranda, António M. A.; Bub, Gil; Srinivas, Shankar

    2015-01-01

    The heart is one of the first organs to develop during mammalian embryogenesis. In the mouse, it starts to form shortly after gastrulation, and is derived primarily from embryonic mesoderm. The embryonic heart is unique in having to perform a mechanical contractile function while undergoing complex morphogenetic remodeling. Approaches to imaging the morphogenesis and contractile activity of the developing heart are important in understanding not only how this remodeling is controlled but also the origin of congenital heart defects (CHDs). Here, we describe approaches for visualizing contractile activity in the developing mouse embryo, using brightfield time lapse microscopy and confocal microscopy of calcium transients. We describe an algorithm for enhancing this image data and quantifying contractile activity from it. Finally we describe how atomic force microscopy can be used to record contractile activity prior to it being microscopically visible. PMID:25610399

  1. Genetically modified proteins: functional improvement and chimeragenesis

    PubMed Central

    Balabanova, Larissa; Golotin, Vasily; Podvolotskaya, Anna; Rasskazov, Valery

    2015-01-01

    This review focuses on the emerging role of site-specific mutagenesis and chimeragenesis for the functional improvement of proteins in areas where traditional protein engineering methods have been extensively used and practically exhausted. The novel path for the creation of the novel proteins has been created on the farther development of the new structure and sequence optimization algorithms for generating and designing the accurate structure models in result of x-ray crystallography studies of a lot of proteins and their mutant forms. Artificial genetic modifications aim to expand nature's repertoire of biomolecules. One of the most exciting potential results of mutagenesis or chimeragenesis finding could be design of effective diagnostics, bio-therapeutics and biocatalysts. A sampling of recent examples is listed below for the in vivo and in vitro genetically improvement of various binding protein and enzyme functions, with references for more in-depth study provided for the reader's benefit. PMID:26211369

  2. Maternal age effects on myometrial expression of contractile proteins, uterine gene expression, and contractile activity during labor in the rat

    PubMed Central

    Elmes, Matthew; Szyszka, Alexandra; Pauliat, Caroline; Clifford, Bethan; Daniel, Zoe; Cheng, Zhangrui; Wathes, Claire; McMullen, Sarah

    2015-01-01

    Advanced maternal age of first time pregnant mothers is associated with prolonged and dysfunctional labor and significant risk of emergency cesarean section. We investigated the influence of maternal age on myometrial contractility, expression of contractile associated proteins (CAPs), and global gene expression in the parturient uterus. Female Wistar rats either 8 (YOUNG n = 10) or 24 (OLDER n = 10) weeks old were fed laboratory chow, mated, and killed during parturition. Myometrial strips were dissected to determine contractile activity, cholesterol (CHOL) and triglycerides (TAG) content, protein expression of connexin-43 (GJA1), prostaglandin-endoperoxide synthase 2 (PTGS2), and caveolin 1 (CAV-1). Maternal plasma concentrations of prostaglandins PGE2, PGF2α, and progesterone were determined by RIA. Global gene expression in uterine samples was compared using Affymetrix Genechip Gene 2.0 ST arrays and Ingenuity Pathway analysis (IPA). Spontaneous contractility in myometrium exhibited by YOUNG rats was threefold greater than OLDER animals (P < 0.027) but maternal age had no significant effect on myometrial CAP expression, lipid profiles, or pregnancy-related hormones. OLDER myometrium increased contractile activity in response to PGF2α, phenylephrine, and carbachol, a response absent in YOUNG rats (all P < 0.002). Microarray analysis identified that maternal age affected expression of genes related to immune and inflammatory responses, lipid transport and metabolism, steroid metabolism, tissue remodeling, and smooth muscle contraction. In conclusion YOUNG laboring rat myometrium seems primed to contract maximally, whereas activity is blunted in OLDER animals and requires stimulation to meet contractile potential. Further work investigating maternal age effects on myometrial function is required with focus on lipid metabolism and inflammatory pathways. PMID:25876907

  3. SIRT1 improves VSMC functions in atherosclerosis.

    PubMed

    Zhang, Ming-Jie; Zhou, Yi; Chen, Lei; Wang, Xu; Long, Chun-Yan; Pi, Yan; Gao, Chang-Yue; Li, Jing-Cheng; Zhang, Li-Li

    2016-05-01

    Despite advancements in diagnosis and treatment of cardiovascular diseases (CVDs), the morbidity and mortality of CVDs are still rising. Atherosclerosis is a chronic inflammatory disease contributing to multiple CVDs. Considering the complexity and severity of atherosclerosis, it is apparent that exploring the mechanisms of atherosclerotic formation and seeking new therapies for patients with atherosclerosis are required to overcome the heavy burden of CVDs on the quality and length of life of the global population. Vascular smooth muscle cells (VSMCs) play a dominant role in functional and structural changes of the arterial walls in response to atherogenic factors. Therefore, improvement of VSMC functions will slow down the development of atherosclerosis to a large extent. Given its protective performances on regulation of cholesterol metabolism and inflammatory responses, SIRT1 has long been known as an anti-atherosclerosis factor. In this review, we focus on the effects of SIRT1 on VSMC functions and thereby the development of atherosclerosis. PMID:27080738

  4. Cross-Functional Team Processes and Patient Functional Improvement

    PubMed Central

    Alexander, Jeffrey A; Lichtenstein, Richard; Jinnett, Kimberly; Wells, Rebecca; Zazzali, James; Liu, Dawei

    2005-01-01

    Objective To test the hypothesis that higher levels of participation and functioning in cross-functional psychiatric treatment teams will be related to improved patient outcomes. Data Sources/Study Setting Primary data were collected during the period 1992–1999. The study was conducted in 40 teams within units treating seriously mentally ill patients in 16 Veterans Affairs hospitals across the U.S. Study Design A longitudinal, multilevel analysis assessed the relationship between individual- and team-level variables and patients' ability to perform activities of daily living (ADL) over time. Team data were collected in 1992, 1994, and 1995. The number of times patient data were collected was dependent on the length of time the patient was treated and varied from 1 to 14 between 1992 and 1999. Key variables included: patients' ADL scores (the dependent variable); measures of team participation and team functioning; the number of days from baseline on which a patient's ADLs were assessed; and several control variables. Data Collection Methods Team data were obtained via self-administered questionnaires distributed to staff on the study teams. Additional team data were obtained via questionnaires completed by unit directors contemporaneously with the staff survey. Patient data were collected by trained clinicians at regular intervals using a standard assessment instrument. Principal Findings Results indicated that patients treated in teams with higher levels of staff participation experienced greater improvement in ADL over time. No differences in ADL change were noted for patients treated in teams with higher levels of team functioning. Conclusions Findings support our premise that team process has important implications for patient outcomes. The results suggest that the level of participation by the team as a whole may be a more important process attribute, in terms of patient improvements in ADLs, than the team's smooth functioning. These findings indicate the

  5. Considerations For Contractile Electroactive Materials and Actuators

    SciTech Connect

    Lenore Rasmussen, Lewis D. Meixler and Charles A. Gentile

    2012-02-29

    Electroactive polymers (EAPs) that bend, swell, ripple (first generation materials), and now contract with low electric input (new development) have been produced. The mechanism of contraction is not well understood. Radionuclide-labeled experiments, molecular modeling, electrolyte experiments, pH experiments, and an ionic concentration experiment were used to determine the chain of events that occur during contraction and, reciprocally, expansion when the polarity is reversed, in these ionic EAPs. Plasma treatment of the electrodes, along with other strategies, allows for the embedded electrodes and the EAP material of the actuator to work and move as a unit, with no detachment, by significantly improving the metal-polymer interface, analogous to nerves and tendons moving with muscles during movement. Challenges involved with prototyping actuation using contractile EAPs are also discussed.

  6. Exercise training improves vascular mitochondrial function.

    PubMed

    Park, Song-Young; Rossman, Matthew J; Gifford, Jayson R; Bharath, Leena P; Bauersachs, Johann; Richardson, Russell S; Abel, E Dale; Symons, J David; Riehle, Christian

    2016-04-01

    Exercise training is recognized to improve cardiac and skeletal muscle mitochondrial respiratory capacity; however, the impact of chronic exercise on vascular mitochondrial respiratory function is unknown. We hypothesized that exercise training concomitantly increases both vascular mitochondrial respiratory capacity and vascular function. Arteries from both sedentary (SED) and swim-trained (EX, 5 wk) mice were compared in terms of mitochondrial respiratory function, mitochondrial content, markers of mitochondrial biogenesis, redox balance, nitric oxide (NO) signaling, and vessel function. Mitochondrial complex I and complex I + II state 3 respiration and the respiratory control ratio (complex I + II state 3 respiration/complex I state 2 respiration) were greater in vessels from EX relative to SED mice, despite similar levels of arterial citrate synthase activity and mitochondrial DNA content. Furthermore, compared with the SED mice, arteries from EX mice displayed elevated transcript levels of peroxisome proliferative activated receptor-γ coactivator-1α and the downstream targets cytochrome c oxidase subunit IV isoform 1,isocitrate dehydrogenase(Idh)2, and Idh3a, increased manganese superoxide dismutase protein expression, increased endothelial NO synthase phosphorylation (Ser(1177)), and suppressed reactive oxygen species generation (all P< 0.05). Although there were no differences in EX and SED mice concerning endothelium-dependent and endothelium-independent vasorelaxation, phenylephrine-induced vasocontraction was blunted in vessels from EX compared with SED mice, and this effect was normalized by NOS inhibition. These training-induced increases in vascular mitochondrial respiratory capacity and evidence of improved redox balance, which may, at least in part, be attributable to elevated NO bioavailability, have the potential to protect against age- and disease-related challenges to arterial function. PMID:26825520

  7. Virtual reality training improves balance function

    PubMed Central

    Mao, Yurong; Chen, Peiming; Li, Le; Huang, Dongfeng

    2014-01-01

    Virtual reality is a new technology that simulates a three-dimensional virtual world on a computer and enables the generation of visual, audio, and haptic feedback for the full immersion of users. Users can interact with and observe objects in three-dimensional visual space without limitation. At present, virtual reality training has been widely used in rehabilitation therapy for balance dysfunction. This paper summarizes related articles and other articles suggesting that virtual reality training can improve balance dysfunction in patients after neurological diseases. When patients perform virtual reality training, the prefrontal, parietal cortical areas and other motor cortical networks are activated. These activations may be involved in the reconstruction of neurons in the cerebral cortex. Growing evidence from clinical studies reveals that virtual reality training improves the neurological function of patients with spinal cord injury, cerebral palsy and other neurological impairments. These findings suggest that virtual reality training can activate the cerebral cortex and improve the spatial orientation capacity of patients, thus facilitating the cortex to control balance and increase motion function. PMID:25368651

  8. Low dose dobutamine stress echocardiography predicts the improvement of left ventricular systolic function in dilated cardiomyopathy

    PubMed Central

    Kitaoka, H; Takata, J; Yabe, T; Hitomi, N; Furuno, T; Doi, Y

    1999-01-01

    OBJECTIVE—To determine whether dobutamine stress echocardiography can predict the improvement of left ventricular systolic function in patients with dilated cardiomyopathy (DCM).
METHODS—Myocardial contractile reserve, as assessed by dobutamine stress echocardiography, was determined in 18 patients with DCM (mean (SD) age 53 (13) years, left ventricular ejection fraction (LVEF) 28 (10)%) and compared with changes in LVEF during a follow up period of 15 (8) months. The LVEF and regional left ventricular wall motion score (0, normal to 4, dyskinesis) of 12 segments in short axis and four chamber views were analysed before and after dobutamine infusion (5-20 µg/kg/min).
RESULTS—During a follow up period of 15 (8) months, a significant improvement in LVEF (> 20%) was found in seven patients but not in the remaining 11. Baseline haemodynamic findings were similar in both groups. Patients with an improvement in follow up LVEF showed a greater change in wall motion score from baseline during dobutamine infusion than patients with no improvement (at rest, 1.7 (0.4) v 1.9 (0.2), NS; dobutamine 10 µg/kg/min, 0.6 (0.4) v 1.2 (0.4), p < 0.05). The percentage change in LVEF during dobutamine infusion was also significantly greater in patients who showed improvement than in those who did not. The change in LVEF during the follow up period (follow up LVEF/baseline LVEF) correlated well with the change in LVEF during dobutamine stress (LVEF at rest/LVEF at dobutamine 10 µg/kg/min; r = 0.74, p < 0.001).
CONCLUSIONS—Changes in left ventricular systolic performance during low dose dobutamine stress echocardiography are a useful marker to predict the outcome of left ventricular systolic function in patients with DCM.


Keywords: dilated cardiomyopathy; dobutamine stress echocardiography; contractile reserve PMID:10212172

  9. Lanczos steps to improve variational wave functions

    NASA Astrophysics Data System (ADS)

    Becca, Federico; Hu, Wen-Jun; Iqbal, Yasir; Parola, Alberto; Poilblanc, Didier; Sorella, Sandro

    2015-09-01

    Gutzwiller-projected fermionic states can be efficiently implemented within quantum Monte Carlo calculations to define extremely accurate variational wave functions for Heisenberg models on frustrated two-dimensional lattices, not only for the ground state but also for low-energy excitations. The application of few Lanczos steps on top of these states further improves their accuracy, allowing calculations on large clusters. In addition, by computing both the energy and its variance, it is possible to obtain reliable estimations of exact results. Here, we report the cases of the frustrated Heisenberg models on square and Kagome lattices.

  10. Identification of contractile vacuole proteins in Trypanosoma cruzi.

    PubMed

    Ulrich, Paul N; Jimenez, Veronica; Park, Miyoung; Martins, Vicente P; Atwood, James; Moles, Kristen; Collins, Dalis; Rohloff, Peter; Tarleton, Rick; Moreno, Silvia N J; Orlando, Ron; Docampo, Roberto

    2011-01-01

    Contractile vacuole complexes are critical components of cell volume regulation and have been shown to have other functional roles in several free-living protists. However, very little is known about the functions of the contractile vacuole complex of the parasite Trypanosoma cruzi, the etiologic agent of Chagas disease, other than a role in osmoregulation. Identification of the protein composition of these organelles is important for understanding their physiological roles. We applied a combined proteomic and bioinfomatic approach to identify proteins localized to the contractile vacuole. Proteomic analysis of a T. cruzi fraction enriched for contractile vacuoles and analyzed by one-dimensional gel electrophoresis and LC-MS/MS resulted in the addition of 109 newly detected proteins to the group of expressed proteins of epimastigotes. We also identified different peptides that map to at least 39 members of the dispersed gene family 1 (DGF-1) providing evidence that many members of this family are simultaneously expressed in epimastigotes. Of the proteins present in the fraction we selected several homologues with known localizations in contractile vacuoles of other organisms and others that we expected to be present in these vacuoles on the basis of their potential roles. We determined the localization of each by expression as GFP-fusion proteins or with specific antibodies. Six of these putative proteins (Rab11, Rab32, AP180, ATPase subunit B, VAMP1, and phosphate transporter) predominantly localized to the vacuole bladder. TcSNARE2.1, TcSNARE2.2, and calmodulin localized to the spongiome. Calmodulin was also cytosolic. Our results demonstrate the utility of combining subcellular fractionation, proteomic analysis, and bioinformatic approaches for localization of organellar proteins that are difficult to detect with whole cell methodologies. The CV localization of the proteins investigated revealed potential novel roles of these organelles in phosphate metabolism

  11. Compensatory Hypertrophy of Skeletal Muscle: Contractile Characteristics

    ERIC Educational Resources Information Center

    Ianuzzo, C. D.; Chen, V.

    1977-01-01

    Describes an experiment using rats that demonstrates contractile characteristics of normal and hypertrophied muscle. Compensatory hypertrophy of the plantaris muscle is induced by surgical removal of the synergistic gastrocnemium muscle. Includes methods for determination of contractile properties of normal and hypertrophied muscle and…

  12. Cardiac Rehabilitation: Improving Function and Reducing Risk.

    PubMed

    Servey, Jessica T; Stephens, Mark

    2016-07-01

    Cardiac rehabilitation is a comprehensive multidisciplinary program individually tailored to the needs of patients with cardiovascular disease. The overall goals focus on improving daily function and reducing cardiovascular risk factors. Cardiac rehabilitation includes interventions aimed at lowering blood pressure and improving lipid and diabetes mellitus control, with tobacco cessation, behavioral counseling, and graded physical activity. The physical activity component typically involves 36 sessions over 12 weeks, during which patients participate in supervised exercise under cardiac monitoring. There are also intensive programs that include up to 72 sessions lasting up to 18 weeks, although these programs are not widely available. Additional components of cardiac rehabilitation include counseling on nutrition, screening for and managing depression, and assuring up-to-date immunizations. Cardiac rehabilitation is covered by Medicare and recommended for patients following myocardial infarction, bypass surgery, and stent placement, and for patients with heart failure, stable angina, and several other conditions. Despite proven benefits in mortality rates, depression, functional capacity, and medication adherence, rates of referral for cardiac rehabilitation are suboptimal. Groups less likely to be referred are older adults, women, patients who do not speak English, and persons living in areas where cardiac rehabilitation is not locally available. Additionally, primary care physicians refer patients less often than cardiologists and cardiothoracic surgeons. PMID:27386722

  13. In Vivo Assessment of Muscle Contractility in Animal Studies.

    PubMed

    Iyer, Shama R; Valencia, Ana P; Hernández-Ochoa, Erick O; Lovering, Richard M

    2016-01-01

    In patients with muscle injury or muscle disease, assessment of muscle damage is typically limited to clinical signs, such as tenderness, strength, range of motion, and more recently, imaging studies. Animal models provide unmitigated access to histological samples, which provide a "direct measure" of damage. However, even with unconstrained access to tissue morphology and biochemistry assays, the findings typically do not account for loss of muscle function. Thus, the most comprehensive measure of the overall health of the muscle is assessment of its primary function, which is to produce contractile force. The majority of animal models testing contractile force have been limited to the muscle groups moving the ankle, with advantages and disadvantages depending on the equipment. Here, we describe in vivo methods to measure torque, to produce a reliable muscle injury, and to follow muscle function within the same animal over time. We also describe in vivo methods to measure tension in the leg and thigh muscles. PMID:27492180

  14. Actomyosin contractility spatiotemporally regulates actin network dynamics in migrating cells.

    PubMed

    Okeyo, Kennedy Omondi; Adachi, Taiji; Sunaga, Junko; Hojo, Masaki

    2009-11-13

    Coupling interactions among mechanical and biochemical factors are important for the realization of various cellular processes that determine cell migration. Although F-actin network dynamics has been the focus of many studies, it is not yet clear how mechanical forces generated by actomyosin contractility spatiotemporally regulate this fundamental aspect of cell migration. In this study, using a combination of fluorescent speckle microscopy and particle imaging velocimetry techniques, we perturbed the actomyosin system and examined quantitatively the consequence of actomyosin contractility on F-actin network flow and deformation in the lamellipodia of actively migrating fish keratocytes. F-actin flow fields were characterized by retrograde flow at the front and anterograde flow at the back of the lamellipodia, and the two flows merged to form a convergence zone of reduced flow intensity. Interestingly, activating or inhibiting actomyosin contractility altered network flow intensity and convergence, suggesting that network dynamics is directly regulated by actomyosin contractility. Moreover, quantitative analysis of F-actin network deformation revealed that the deformation was significantly negative and predominant in the direction of cell migration. Furthermore, perturbation experiments revealed that the deformation was a function of actomyosin contractility. Based on these results, we suggest that the actin cytoskeletal structure is a mechanically self-regulating system, and we propose an elaborate pathway for the spatiotemporal self-regulation of the actin cytoskeletal structure during cell migration. In the proposed pathway, mechanical forces generated by actomyosin interactions are considered central to the realization of the various mechanochemical processes that determine cell motility. PMID:19665125

  15. Autologous Fat Grafting Improves Facial Nerve Function

    PubMed Central

    Klinger, Marco; Lisa, Andrea; Caviggioli, Fabio; Maione, Luca; Murolo, Matteo; Vinci, Valeriano; Klinger, Francesco Maria

    2015-01-01

    We describe the case of a 45-year-old male patient who presented a retractile and painful scar in the nasolabial fold due to trauma which determined partial motor impairment of the mouth movements. We subsequently treated him with autologous fat grafting according to Coleman's technique. Clinical assessments were performed at 5 and 14 days and 1, 3, and 6 months after surgical procedure and we observed a progressive release of scar retraction together with an important improvement of pain symptoms. A second procedure was performed 6 months after the previous one. We observed total restoration of mimic movements within one-year follow-up. The case described confirms autologous fat grafting regenerative effect on scar tissue enlightening a possible therapeutic effect on peripheral nerve activity, hypothesizing that its entrapment into scar tissue can determine a partial loss of function. PMID:26167327

  16. Chronic Contractile Dysfunction without Hypertrophy Does Not Provoke a Compensatory Transcriptional Response in Mouse Hearts.

    PubMed

    Matkovich, Scot J; Grubb, David R; McMullen, Julie R; Woodcock, Elizabeth A

    2016-01-01

    Diseased myocardium from humans and experimental animal models shows heightened expression and activity of a specific subtype of phospholipase C (PLC), the splice variant PLCβ1b. Previous studies from our group showed that increasing PLCβ1b expression in adult mouse hearts by viral transduction was sufficient to cause sustained contractile dysfunction of rapid onset, which was maintained indefinitely in the absence of other pathological changes in the myocardium. We hypothesized that impaired contractility alone would be sufficient to induce a compensatory transcriptional response. Unbiased, comprehensive mRNA-sequencing was performed on 6 biological replicates of rAAV6-treated blank, PLCβ1b and PLCβ1a (closely related but inactive splice variant) hearts 8 weeks after injection, when reduced contractility was manifest in PLCβ1b hearts without evidence of induced hypertrophy. Expression of PLCβ1b resulted in expression changes in only 9 genes at FDR<0.1 when compared with control and these genes appeared unrelated to contractility. Importantly, PLCβ1a caused similar mild expression changes to PLCβ1b, despite a complete lack of effect of this isoform on cardiac contractility. We conclude that contractile depression caused by PLCβ1b activation is largely independent of changes in the transcriptome, and thus that lowered contractility is not sufficient in itself to provoke measurable transcriptomic alterations. In addition, our data stress the importance of a stringent control group to filter out transcriptional changes unrelated to cardiac function. PMID:27359099

  17. Chronic Contractile Dysfunction without Hypertrophy Does Not Provoke a Compensatory Transcriptional Response in Mouse Hearts

    PubMed Central

    Grubb, David R.; McMullen, Julie R.; Woodcock, Elizabeth A.

    2016-01-01

    Diseased myocardium from humans and experimental animal models shows heightened expression and activity of a specific subtype of phospholipase C (PLC), the splice variant PLCβ1b. Previous studies from our group showed that increasing PLCβ1b expression in adult mouse hearts by viral transduction was sufficient to cause sustained contractile dysfunction of rapid onset, which was maintained indefinitely in the absence of other pathological changes in the myocardium. We hypothesized that impaired contractility alone would be sufficient to induce a compensatory transcriptional response. Unbiased, comprehensive mRNA-sequencing was performed on 6 biological replicates of rAAV6-treated blank, PLCβ1b and PLCβ1a (closely related but inactive splice variant) hearts 8 weeks after injection, when reduced contractility was manifest in PLCβ1b hearts without evidence of induced hypertrophy. Expression of PLCβ1b resulted in expression changes in only 9 genes at FDR<0.1 when compared with control and these genes appeared unrelated to contractility. Importantly, PLCβ1a caused similar mild expression changes to PLCβ1b, despite a complete lack of effect of this isoform on cardiac contractility. We conclude that contractile depression caused by PLCβ1b activation is largely independent of changes in the transcriptome, and thus that lowered contractility is not sufficient in itself to provoke measurable transcriptomic alterations. In addition, our data stress the importance of a stringent control group to filter out transcriptional changes unrelated to cardiac function. PMID:27359099

  18. Regulation of Endothelial Barrier Function by TGF-β type I Receptor ALK5: Potential Role of Contractile Mechanisms and Heat Shock Protein 90

    PubMed Central

    Antonov, Alexander S.; Antonova, Galina N.; Fujii, Makiko; Dijke, Peter ten; Handa, Vaishali; Catravas, John D.; Verin, Alexander D.

    2013-01-01

    Multifunctional cytokine transforming growth factor-beta (TGF-β1) plays a critical role in the pathogenesis of acute lung inflammation by controlling endothelial monolayer permeability. TGF-β1 regulates endothelial cell (EC) functions via two distinct receptors, activin receptor-like kinase 1 (ALK1) and activin receptor-like kinase 5 (ALK5). The precise roles of ALK1 and ALK5 in the regulation of TGF-β1-induced lung endothelium dysfunction remain mostly unknown. We now report that adenoviral infection with constitutively active ALK5 (caALK5), but not caALK1, induces EC retraction and that this receptor predominantly controls EC permeability. We demonstrate that ubiquitinated ALK5 and phosphorylated heat shock protein 27 (phospho-Hsp27) specifically accumulate in the cytoskeleton fraction, which parallels with microtubule collapse, cortical actin disassembly and increased EC permeability. We have found that ALK1 and ALK5 interact with heat shock protein 90 (Hsp90). Moreover, the Hsp90 inhibitor radicicol (RA) prevents accumulation of ubiquitinated caALK5 and phospho-Hsp27 in the cytoskeletal fraction and restore the decreased EC permeability induced by caALK5. We hypothesize that specific translocation of ubiquitinated ALK5 receptor into the cytoskeleton compartment due to its lack of degradation is the mechanism that causes the divergence of caALK1 and caALK5 signaling. PMID:21465483

  19. Structural and Functional Studies of gpX of Escherichia coli Phage P2 Reveal a Widespread Role for LysM Domains in the Baseplates of Contractile-Tailed Phages

    PubMed Central

    Fatehi Hassanabad, Mostafa; Chang, Tom; Pirani, Nawaz; Bona, Diane; Edwards, Aled M.

    2013-01-01

    A variety of bacterial pathogenicity determinants, including the type VI secretion system and the virulence cassettes from Photorhabdus and Serratia, share an evolutionary origin with contractile-tailed myophages. The well-characterized Escherichia coli phage P2 provides an excellent system for studies related to these systems, as its protein composition appears to represent the “minimal” myophage tail. In this study, we used nuclear magnetic resonance (NMR) spectroscopy to determine the solution structure of gpX, a 68-residue tail baseplate protein. Although the sequence and structure of gpX are similar to those of LysM domains, which are a large family associated with peptidoglycan binding, we did not detect a peptidoglycan-binding activity for gpX. However, bioinformatic analysis revealed that half of all myophages, including all that possess phage T4-like baseplates, encode a tail protein with a LysM-like domain, emphasizing a widespread role for this domain in baseplate function. While phage P2 gpX comprises only a single LysM domain, many myophages display LysM domain fusions with other tail proteins, such as the DNA circulation protein found in Mu-like phages and gp53 of T4-like phages. Electron microscopy of P2 phage particles with an incorporated gpX-maltose binding protein fusion revealed that gpX is located at the top of the baseplate, near the junction of the baseplate and tail tube. gpW, the orthologue of phage T4 gp25, was also found to localize to this region. A general colocalization of LysM-like domains and gpW homologues in diverse phages is supported by our bioinformatic analysis. PMID:24097944

  20. Functional dysphonia: strategies to improve patient outcomes.

    PubMed

    Behlau, Mara; Madazio, Glaucya; Oliveira, Gisele

    2015-01-01

    Functional dysphonia (FD) refers to a voice problem in the absence of a physical condition. It is a multifaceted voice disorder. There is no consensus with regard to its definition and inclusion criteria for diagnosis. FD has many predisposing and precipitating factors, which may include genetic susceptibility, psychological traits, and the vocal behavior itself. The assessment of voice disorders should be multidimensional. In addition to the clinical examination, auditory-perceptual, acoustic, and self-assessment analyses are very important. Self-assessment was introduced in the field of voice 25 years ago and has produced a major impact in the clinical and scientific scenario. The choice of treatment for FD is vocal rehabilitation by means of direct therapy; however, compliance has been an issue, except for cases of functional aphonia or when an intensive training is administered. Nevertheless, there are currently no controlled studies that have explored the different options of treatment regimens for these patients. Strategies to improve patient outcome involve proper multidisciplinary diagnosis in order to exclude neurological and psychiatric disorders, careful voice documentation with quantitative measurement and qualitative description of the vocal deviation for comparison after treatment, acoustic evaluation to gather data on the mechanism involved in voice production, self-assessment questionnaires to map the impact of the voice problem on the basis of the patient's perspective, referral to psychological evaluation in cases of suspected clinical anxiety and/or depression, identification of dysfunctional coping strategies, self-regulation data to assist patients with their vocal load, and direct and intensive vocal rehabilitation to reduce psychological resistance and to reassure patient's recovery. An international multicentric effort, involving a large population of voice-disordered patients with no physical pathology, could produce enough data for

  1. Functional dysphonia: strategies to improve patient outcomes

    PubMed Central

    Behlau, Mara; Madazio, Glaucya; Oliveira, Gisele

    2015-01-01

    Functional dysphonia (FD) refers to a voice problem in the absence of a physical condition. It is a multifaceted voice disorder. There is no consensus with regard to its definition and inclusion criteria for diagnosis. FD has many predisposing and precipitating factors, which may include genetic susceptibility, psychological traits, and the vocal behavior itself. The assessment of voice disorders should be multidimensional. In addition to the clinical examination, auditory-perceptual, acoustic, and self-assessment analyses are very important. Self-assessment was introduced in the field of voice 25 years ago and has produced a major impact in the clinical and scientific scenario. The choice of treatment for FD is vocal rehabilitation by means of direct therapy; however, compliance has been an issue, except for cases of functional aphonia or when an intensive training is administered. Nevertheless, there are currently no controlled studies that have explored the different options of treatment regimens for these patients. Strategies to improve patient outcome involve proper multidisciplinary diagnosis in order to exclude neurological and psychiatric disorders, careful voice documentation with quantitative measurement and qualitative description of the vocal deviation for comparison after treatment, acoustic evaluation to gather data on the mechanism involved in voice production, self-assessment questionnaires to map the impact of the voice problem on the basis of the patient’s perspective, referral to psychological evaluation in cases of suspected clinical anxiety and/or depression, identification of dysfunctional coping strategies, self-regulation data to assist patients with their vocal load, and direct and intensive vocal rehabilitation to reduce psychological resistance and to reassure patient’s recovery. An international multicentric effort, involving a large population of voice-disordered patients with no physical pathology, could produce enough data for

  2. Vitamin d and rehabilitation: improving functional outcomes.

    PubMed

    Shinchuk, Leonid M; Shinchuk, Leonid; Holick, Michael F

    2007-06-01

    Vitamin D inadequacy is pandemic among rehabilitation patients in both inpatient and outpatient settings. Male and female patients of all ages and ethnic backgrounds are affected. Vitamin D deficiency causes osteopenia, precipitates and exacerbates osteoporosis, causes the painful bone disease osteomalacia, and worsens proximal muscle strength and postural sway. Vitamin D inadequacy can be prevented by sensible sun exposure and adequate dietary intake with supplementation. Vitamin D status is determined by measurement of serum 25-hydroxyvitamin D. The recommended healthful serum level is between 30 and 60 ng/mL. 25-Hydroxyvitamin D levels of >30 ng/mL are sufficient to suppress parathyroid hormone production and to maximize the efficiency of dietary calcium absorption from the small intestine. This can be accomplished by ingesting 1000 IU of vitamin D(3) per day, or by taking 50,000 IU of vitamin D(2) every 2 weeks. Vitamin D toxicity is observed when 25-hydroxyvitamin D levels exceed 150 ng/mL. Identification and treatment of vitamin D deficiency reduces the risk of vertebral and nonvertebral fractures by improving bone health and musculoskeletal function. Vitamin D deficiency and osteomalacia should be considered in the differential diagnosis of patients with musculoskeletal pain, fibromyalgia, chronic fatigue syndrome, or myositis. There is a need for better education of health professionals and the general public regarding the optimization of vitamin D status in the care of rehabilitation patients. PMID:17507730

  3. Considerations for Contractile Electroactive Materials and Actuators

    SciTech Connect

    Rasmussen, Lenore; Erickson, Carl J.; Meixler, Lewis D.; Ascione, George; Gentile, Charles A.; Tilson, Carl; Bernasek, Stephen L.; Abelev, Esta

    2010-02-19

    Ras Labs produces electroactive polymer (EAP) based materials and actuators that bend, swell, ripple and now contract (new development) with low electric input. This is an important attribute because of the ability of contraction to produce life-like motion. The mechanism of contraction is not well understood. Radionuclide-labeled experiments were conducted to follow the movement of electrolytes and water in these EAPs when activated. Extreme temperature experiments were performed on the contractile EAPs with very favorable results. One of the biggest challenges in developing these actuators, however, is the electrode-EAP interface because of the pronounced movement of the EAP. Plasma treatments of metallic electrodes were investigated in order to improve the attachment of the embedded electrodes to the EAP material. Surface analysis, adhesive testing, and mechanical testing were conducted to test metal surfaces and metal-polymer interfaces. The nitrogen plasma treatment of titanium produced a strong metal-polymer interface; however, oxygen plasma treatment of both stainless steel and titanium produced even stronger metal-polymer interfaces. Plasma treatment of the electrodes allows for the embedded electrodes and the EAP material of the actuator to work and move as a unit, with no detachment, by significantly improving the metal-polymer interface.

  4. Adult progenitor cell transplantation influences contractile performance and calcium handling of recipient cardiomyocytes.

    PubMed

    Lee, Joon; Stagg, Mark A; Fukushima, Satsuki; Soppa, Gopal K R; Siedlecka, Urszula; Youssef, Samuel J; Suzuki, Ken; Yacoub, Magdi H; Terracciano, Cesare M N

    2009-04-01

    Adult progenitor cell transplantation has been proposed for the treatment of heart failure, but the mechanisms effecting functional improvements remain unknown. The aim of this study was to test the hypothesis that, in failing hearts treated with cell transplantation, the mechanical properties and excitation-contraction coupling of recipient cardiomyocytes are altered. Adult rats underwent coronary artery ligation, leading to myocardial infarction and chronic heart failure. After 3 wk, they received intramyocardial injections of either 10(7) green fluorescence protein (GFP)-positive bone marrow mononuclear cells or 5 x 10(6) GFP-positive skeletal myoblasts. Four weeks after injection, both cell types increased ejection fraction and reduced cardiomyocyte size. The contractility of isolated GFP-negative cardiomyocytes was monitored by sarcomere shortening assessment, Ca(2+) handling by indo-1 and fluo-4 fluorescence, and electrophysiology by patch-clamping techniques. Injection of either bone marrow cells or skeletal myoblasts normalized the impaired contractile performance and the prolonged time to peak of the Ca(2+) transient observed in failing cardiomyocytes. The smaller and slower L-type Ca(2+) current observed in heart failure normalized after skeletal myoblast, but not bone marrow cell, transplantation. Measurement of Ca(2+) sparks suggested a normalization of sarcoplasmic reticulum Ca(2+) leak after skeletal myoblast transplantation. The increased Ca(2+) wave frequency observed in failing myocytes was reduced by either bone marrow cells or skeletal myoblasts. In conclusion, the morphology, contractile performance, and excitation-contraction coupling of individual recipient cardiomyocytes are altered in failing hearts treated with adult progenitor cell transplantation. PMID:19181964

  5. MDMA induces cardiac contractile dysfunction through autophagy upregulation and lysosome destabilization in rats.

    PubMed

    Shintani-ishida, Kaori; Saka, Kanju; Yamaguchi, Koji; Hayashida, Makiko; Nagai, Hisashi; Takemura, Genzou; Yoshida, Ken-ichi

    2014-05-01

    The underlying mechanisms of cardiotoxicity of 3,4-methylenedioxymethylamphetamine (MDMA, "ecstasy") abuse are unclear. Autophagy exerts either adaptive or maladaptive effects on cardiac function in various pathological settings, but nothing is known on the role of autophagy in the MDMA cardiotoxicity. Here, we investigated the mechanism through which autophagy may be involved in MDMA-induced cardiac contractile dysfunction. Rats were injected intraperitoneally with MDMA (20mg/kg) or saline. Left ventricular (LV) echocardiography and LV pressure measurement demonstrated reduction of LV systolic contractility 24h after MDMA administration. Western blot analysis showed a time-dependent increase in the levels of microtubule-associated protein light chain 3-II (LC3-II) and cathepsin-D after MDMA administration. Electron microscopy showed the presence of autophagic vacuoles in cardiomyocytes. MDMA upregulated phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) at Thr172, mammalian target of rapamycin (mTOR) at Thr2446, Raptor at Ser792, and Unc51-like kinase (ULK1) at Ser555, suggesting activation of autophagy through the AMPK-mTOR pathway. The effects of autophagic inhibitors 3-methyladenine (3-MA) and chloroquine (CQ) on LC3-II levels indicated that MDMA enhanced autophagosome formation, but attenuated autophagosome clearance. MDMA also induced release of cathepsins into cytosol, and western blotting and electron microscopy showed cardiac troponin I (cTnI) degradation and myofibril damage, respectively. 3-MA, CQ, and a lysosomal inhibitor, E64c, inhibited cTnI proteolysis and improved contractile dysfunction after MDMA administration. In conclusion, MDMA causes lysosome destabilization following activation of the autophagy-lysosomal pathway, through which released lysosomal proteases damage myofibrils and induce LV systolic dysfunction in rat heart. PMID:24491919

  6. Improved algorithm for calculating the Chandrasekhar function

    NASA Astrophysics Data System (ADS)

    Jablonski, A.

    2013-02-01

    algorithms by selecting ranges of the argument omega in which the performance is the fastest. Reasons for the new version: Some of the theoretical models describing electron transport in condensed matter need a source of the Chandrasekhar H function values with an accuracy of at least 10 decimal places. Additionally, calculations of this function should be as fast as possible since frequent calls to a subroutine providing this function are made (e.g., numerical evaluation of a double integral with a complicated integrand containing the H function). Both conditions were satisfied in the algorithm previously published [1]. However, it has been found that a proper selection of the quadrature in an integral representation of the Chandrasekhar function may considerably decrease the running time. By suitable selection of the number of abscissas in Gauss-Legendre quadrature, the execution time was decreased by a factor of more than 20. Simultaneously, the accuracy of results has not been affected. Summary of revisions: (1) As in previous work [1], two integral representations of the Chandrasekhar function, H(x,omega), were considered: the expression published by Dudarev and Whelan [2] and the expression published by Davidović et al. [3]. The algorithms implementing these representations were designated A and B, respectively. All integrals in these implementations were previously calculated using Romberg quadrature. It has been found, however, that the use of Gauss-Legendre quadrature considerably improved the performance of both algorithms. Two conditions have to be satisfied. (i) The number of abscissas, N, has to be rather large, and (ii) the abscissas and corresponding weights should be determined with accuracy as high as possible. The abscissas and weights are available for N=16, 20, 24, 32, 40, 48, 64, 80, and 96 with accuracy of 20 decimal places [4], and all these values were introduced into a new procedure GAUSS replacing procedure ROMBERG. Due to the fact that the

  7. Lidocaine decreases the xylazine-evoked contractility in pregnant cows.

    PubMed

    Piccinno, M; Rizzo, A; Mutinati, M; D'Onghia, G; Sciorsci, R L

    2016-08-01

    The objective of this in vitro study was to evaluate and compare the effects of xylazine on basal uterine contractility of bovine pregnant uterine strips and that of lidocaine on xylazine-sensitized bovine pregnant uterine strips, at different stages of pregnancy. Basal contractility was evaluated in an isolated organ bath and the functionality of the strips throughout the experiment was evaluated using a dose of carbachol (10(-5)M). Uterine motility, expressed with amplitude, frequency of contractions as well as the area under the curve, was recorded in different stages of pregnancy and data were collected at 15-min intervals (5-min before and 5-min after xylazine administration and 5-min after lidocaine addition on the plateau contraction induced by xylazine). Uterine motility increased in all the stages of pregnancy after xylazine addition and gradually decreased after treatment with lidocaine. These data suggest that lidocaine might decrease the tonic effect induced by xylazine on bovine pregnant uteri. PMID:27474006

  8. Contractility of single cardiomyocytes differentiated from pluripotent stem cells depends on physiological shape and substrate stiffness

    PubMed Central

    Ribeiro, Alexandre J. S.; Ang, Yen-Sin; Fu, Ji-Dong; Rivas, Renee N.; Mohamed, Tamer M. A.; Higgs, Gadryn C.; Srivastava, Deepak; Pruitt, Beth L.

    2015-01-01

    Single cardiomyocytes contain myofibrils that harbor the sarcomere-based contractile machinery of the myocardium. Cardiomyocytes differentiated from human pluripotent stem cells (hPSC-CMs) have potential as an in vitro model of heart activity. However, their fetal-like misalignment of myofibrils limits their usefulness for modeling contractile activity. We analyzed the effects of cell shape and substrate stiffness on the shortening and movement of labeled sarcomeres and the translation of sarcomere activity to mechanical output (contractility) in live engineered hPSC-CMs. Single hPSC-CMs were cultured on polyacrylamide substrates of physiological stiffness (10 kPa), and Matrigel micropatterns were used to generate physiological shapes (2,000-µm2 rectangles with length:width aspect ratios of 5:1–7:1) and a mature alignment of myofibrils. Translation of sarcomere shortening to mechanical output was highest in 7:1 hPSC-CMs. Increased substrate stiffness and applied overstretch induced myofibril defects in 7:1 hPSC-CMs and decreased mechanical output. Inhibitors of nonmuscle myosin activity repressed the assembly of myofibrils, showing that subcellular tension drives the improved contractile activity in these engineered hPSC-CMs. Other factors associated with improved contractility were axially directed calcium flow, systematic mitochondrial distribution, more mature electrophysiology, and evidence of transverse-tubule formation. These findings support the potential of these engineered hPSC-CMs as powerful models for studying myocardial contractility at the cellular level. PMID:26417073

  9. [Ventricular contractility: Physiology and clinical projection].

    PubMed

    Domenech, Raúl J; Parra, Víctor M

    2016-06-01

    The contractile state of the heart is the result of myocardial contractility, the intrinsic mechanism that regulates the force and the shortening of the ventricle and determines the ventricular ejection volume. However, the ejection volume is also modulated by ventricular preload (diastolic ventricular volume) and afterload (resistance to ejection). Accordingly, a decrease in contractility may be masked by changes in preload or afterload, maintaining a normal ejection volume and delaying the diagnosis of myocardial damage. Thus, it is necessary to develop a non-invasive method to measure contractility in the clinical practice. We review in this article the basic principles of cardiac contraction, the concept of contractility and its measurement with the ventricular pressure-volume loop, an experimental method that also measures most of the hemodynamic variables of the cardiac cycle including preload, afterload, ventricular work, ventricular lusitropy and arterial elastance. This method has been recently validated in cardiac patients and allows to evaluate the evolution of contractility in heart failure in a non invasive way. Although some modifications are still necessary, it will probably have an extensive use in practical cardiology in the near future. PMID:27598497

  10. Redox regulation of muscle adaptations to contractile activity and aging

    PubMed Central

    2015-01-01

    Superoxide and nitric oxide are generated by skeletal muscle, and these species are increased by contractile activity. Mitochondria have long been assumed to play the primary role in generation of superoxide in muscle, but recent studies indicate that, during contractile activity, membrane-localized NADPH oxidase(s) rapidly generate(s) superoxide that plays a role in redox signaling. This process is important in upregulation of rapid and specific cytoprotective responses that aid maintenance of cell viability following contractile activity, but the overall extent to which redox signaling contributes to regulation of muscle metabolism and homeostasis following contractile activity is currently unclear, as is identification of key redox-sensitive protein targets involved in these processes. Reactive oxygen and nitrogen species have also been implicated in the loss of muscle mass and function that occurs with aging, although recent work has questioned whether oxidative damage plays a key role in these processes. A failure of redox signaling occurs in muscle during aging and may contribute to the age-related loss of muscle fibers. Whether such changes in redox signaling reflect primary age-related changes or are secondary to the fundamental mechanisms is unclear. For instance, denervated muscle fibers within muscles from aged rodents or humans appear to generate large amounts of mitochondrial hydrogen peroxide that could influence adjacent innervated fibers. Thus, in this instance, a “secondary” source of reactive oxygen species may be potentially generated as a result of a primary age-related pathology (loss of neurons), but, nevertheless, may contribute to loss of muscle mass and function during aging. PMID:25792715

  11. Protrusive and Contractile Forces of Spreading Human Neutrophils.

    PubMed

    Henry, Steven J; Chen, Christopher S; Crocker, John C; Hammer, Daniel A

    2015-08-18

    Human neutrophils are mediators of innate immunity and undergo dramatic shape changes at all stages of their functional life cycle. In this work, we quantified the forces associated with a neutrophil's morphological transition from a nonadherent, quiescent sphere to its adherent and spread state. We did this by tracking, with high spatial and temporal resolution, the cell's mechanical behavior during spreading on microfabricated post-array detectors printed with the extracellular matrix protein fibronectin. Two dominant mechanical regimes were observed: transient protrusion and steady-state contraction. During spreading, a wave of protrusive force (75 ± 8 pN/post) propagates radially outward from the cell center at a speed of 206 ± 28 nm/s. Once completed, the cells enter a sustained contractile state. Although post engagement during contraction was continuously varying, posts within the core of the contact zone were less contractile (-20 ± 10 pN/post) than those residing at the geometric perimeter (-106 ± 10 pN/post). The magnitude of the protrusive force was found to be unchanged in response to cytoskeletal inhibitors of lamellipodium formation and myosin II-mediated contractility. However, cytochalasin B, known to reduce cortical tension in neutrophils, slowed spreading velocity (61 ± 37 nm/s) without significantly reducing protrusive force. Relaxation of the actin cortical shell was a prerequisite for spreading on post arrays as demonstrated by stiffening in response to jasplakinolide and the abrogation of spreading. ROCK and myosin II inhibition reduced long-term contractility. Function blocking antibody studies revealed haptokinetic spreading was induced by β2 integrin ligation. Neutrophils were found to moderately invaginate the post arrays to a depth of ∼1 μm as measured from spinning disk confocal microscopy. Our work suggests a competition of adhesion energy, cortical tension, and the relaxation of cortical tension is at play at the onset of

  12. Protrusive and Contractile Forces of Spreading Human Neutrophils

    PubMed Central

    Henry, Steven J.; Chen, Christopher S.; Crocker, John C.; Hammer, Daniel A.

    2015-01-01

    Human neutrophils are mediators of innate immunity and undergo dramatic shape changes at all stages of their functional life cycle. In this work, we quantified the forces associated with a neutrophil’s morphological transition from a nonadherent, quiescent sphere to its adherent and spread state. We did this by tracking, with high spatial and temporal resolution, the cell’s mechanical behavior during spreading on microfabricated post-array detectors printed with the extracellular matrix protein fibronectin. Two dominant mechanical regimes were observed: transient protrusion and steady-state contraction. During spreading, a wave of protrusive force (75 ± 8 pN/post) propagates radially outward from the cell center at a speed of 206 ± 28 nm/s. Once completed, the cells enter a sustained contractile state. Although post engagement during contraction was continuously varying, posts within the core of the contact zone were less contractile (−20 ± 10 pN/post) than those residing at the geometric perimeter (−106 ± 10 pN/post). The magnitude of the protrusive force was found to be unchanged in response to cytoskeletal inhibitors of lamellipodium formation and myosin II-mediated contractility. However, cytochalasin B, known to reduce cortical tension in neutrophils, slowed spreading velocity (61 ± 37 nm/s) without significantly reducing protrusive force. Relaxation of the actin cortical shell was a prerequisite for spreading on post arrays as demonstrated by stiffening in response to jasplakinolide and the abrogation of spreading. ROCK and myosin II inhibition reduced long-term contractility. Function blocking antibody studies revealed haptokinetic spreading was induced by β2 integrin ligation. Neutrophils were found to moderately invaginate the post arrays to a depth of ∼1 μm as measured from spinning disk confocal microscopy. Our work suggests a competition of adhesion energy, cortical tension, and the relaxation of cortical tension is at play at the

  13. A method to test contractility of the supraspinatus muscle in mouse, rat, and rabbit.

    PubMed

    Valencia, Ana P; Iyer, Shama R; Pratt, Stephen J P; Gilotra, Mohit N; Lovering, Richard M

    2016-02-01

    The rotator cuff (RTC) muscles not only generate movement but also provide important shoulder joint stability. RTC tears, particularly in the supraspinatus muscle, are a common clinical problem. Despite some biological healing after RTC repair, persistent problems include poor functional outcomes with high retear rates after surgical repair. Animal models allow further exploration of the sequela of RTC injury such as fibrosis, inflammation, and fatty infiltration, but there are few options regarding contractility for mouse, rat, and rabbit. Histological findings can provide a "direct measure" of damage, but the most comprehensive measure of the overall health of the muscle is contractile force. However, information regarding normal supraspinatus size and contractile function is scarce. Animal models provide the means to compare muscle histology, imaging, and contractility within individual muscles in various models of injury and disease, but to date, most testing of animal contractile force has been limited primarily to hindlimb muscles. Here, we describe an in vivo method to assess contractility of the supraspinatus muscle and describe differences in methods and representative outcomes for mouse, rat, and rabbit. PMID:26586911

  14. Improving Sensorimotor Function Using Stochastic Vestibular Stimulation

    NASA Technical Reports Server (NTRS)

    Galvan, R. C.; Clark, T. K.; Merfeld, D. M.; Bloomberg, J. J.; Mulavara, A. P.; Oman, C. M.

    2014-01-01

    Astronauts experience sensorimotor changes during spaceflight, particularly during G-transition phases. Post flight sensorimotor changes may include postural and gait instability, spatial disorientation, and visual performance decrements, all of which can degrade operational capabilities of the astronauts and endanger the crew. Crewmember safety would be improved if these detrimental effects of spaceflight could be mitigated by a sensorimotor countermeasure and even further if adaptation to baseline could be facilitated. The goal of this research is to investigate the potential use of stochastic vestibular stimulation (SVS) as a technology to improve sensorimotor function. We hypothesize that low levels of SVS will improve sensorimotor performance through stochastic resonance (SR). The SR phenomenon occurs when the response of a nonlinear system to a weak input signal is optimized by the application of a particular nonzero level of noise. Two studies have been initiated to investigate the beneficial effects and potential practical usage of SVS. In both studies, electrical vestibular stimulation is applied via electrodes on the mastoid processes using a constant current stimulator. The first study aims to determine the repeatability of the effect of vestibular stimulation on sensorimotor performance and perception in order to better understand the practical use of SVS. The beneficial effect of low levels of SVS on balance performance has been shown in the past. This research uses the same balance task repeated multiple times within a day and across days to study the repeatability of the stimulation effects. The balance test consists of 50 sec trials in which the subject stands with his or her feet together, arms crossed, and eyes closed on compliant foam. Varying levels of SVS, ranging from 0-700 micro A, are applied across different trials. The subject-specific optimal SVS level is that which results in the best balance performance as measured by inertial

  15. Aerobic exercise training improves whole muscle and single myofiber size and function in older women

    PubMed Central

    Konopka, Adam R.; Douglass, Matthew D.; Minchev, Kiril; Kaminsky, Leonard A.; Trappe, Todd A.; Trappe, Scott

    2009-01-01

    To comprehensively assess the influence of aerobic training on muscle size and function, we examined seven older women (71 ± 2 yr) before and after 12 wk of cycle ergometer training. The training program increased (P < 0.05) aerobic capacity by 30 ± 6%. Quadriceps muscle volume, determined by magnetic resonance imaging (MRI), was 12 ± 2% greater (P < 0.05) after training and knee extensor power increased 55 ± 7% (P < 0.05). Muscle biopsies were obtained from the vastus lateralis to determine size and contractile properties of individual slow (MHC I) and fast (MHC IIa) myofibers, myosin light chain (MLC) composition, and muscle protein concentration. Aerobic training increased (P < 0.05) MHC I fiber size 16 ± 5%, while MHC IIa fiber size was unchanged. MHC I peak power was elevated 21 ± 8% (P < 0.05) after training, while MHC IIa peak power was unaltered. Peak force (Po) was unchanged in both fiber types, while normalized force (Po/cross-sectional area) was 10% lower (P < 0.05) for both MHC I and MHC IIa fibers after training. The decrease in normalized force was likely related to a reduction (P < 0.05) in myofibrillar protein concentration after training. In the absence of an increase in Po, the increase in MHC I peak power was mediated through an increased (P < 0.05) maximum contraction velocity (Vo) of MHC I fibers only. The relative proportion of MLC1s (Pre: 0.62 ± 0.01; Post: 0.58 ± 0.01) was lower (P < 0.05) in MHC I myofibers after training, while no differences were present for MLC2s and MLC3f isoforms. These data indicate that aerobic exercise training improves muscle function through remodeling the contractile properties at the myofiber level, in addition to pronounced muscle hypertrophy. Progressive aerobic exercise training should be considered a viable exercise modality to combat sarcopenia in the elderly population. PMID:19692660

  16. Second window of preconditioning normalizes palmitate use for oxidation and improves function during low-flow ischaemia

    PubMed Central

    Kudej, Raymond K.; Fasano, Mathew; Zhao, Xin; Lopaschuk, Gary D.; Fischer, Susan K.; Vatner, Dorothy E.; Vatner, Stephen F.; Lewandowski, E. Douglas

    2011-01-01

    Aims Although a major mechanism for cardioprotection is altered metabolism, little is known regarding metabolic changes in ischaemic preconditioning and subsequent ischaemia. Our objective was to examine the effects of the second window of preconditioning (SWOP), the delayed phase of preconditioning against infarction and stunning, on long-chain free fatty acid (LCFA) oxidation during ischaemia in chronically instrumented, conscious pigs. Methods and results We studied three groups: (i) normal baseline perfusion (n = 5); (ii) coronary artery stenosis (CAS; n = 5); (iii) CAS 24 h following 2 × 10 min coronary occlusions and 10 min reperfusion (n = 7). Ischaemia was induced by a left anterior descending (LAD) stenosis (40% flow reduction) for 90 min, dropping systolic wall thickening by 72%. LCFA oxidation was assessed following LAD infusion of 13C palmitate, i.e. during control or stenosis, by in vitro nuclear magnetic resonance of the sampled myocardium. Stenosis reduced subendocardial blood flow subendocardially, but not subepicardial, yet induced transmural reductions in LCFA oxidation and increased non-oxidative glycolysis. During stenosis, preconditioned hearts showed normalized contributions of LCFA to oxidative ATP synthesis, despite increased lactate accumulation. SWOP induced a shift towards LCFA oxidation during stenosis, despite increased malonyl-CoA, and marked protection of contractile function with a significant improvement in systolic wall thickening. Conclusion Thus, the second window of preconditioning normalized oxidative metabolism of LCFA during subsequent ischaemia despite elevated non-oxidative glycolysis and malonyl-CoA and was linked to protection of regional contractile function resulting in improved mechanical performance. Interestingly, the metabolic responses occurred transmurally while ischaemia was restricted solely to the subendocardium. PMID:21835931

  17. Depressed phosphatidic acid-induced contractile activity of failing cardiomyocytes.

    PubMed

    Tappia, Paramjit S; Maddaford, Thane G; Hurtado, Cecilia; Panagia, Vincenzo; Pierce, Grant N

    2003-01-10

    The effects of phosphatidic acid (PA), a known inotropic agent, on Ca(2+) transients and contractile activity of cardiomyocytes in congestive heart failure (CHF) due to myocardial infarction were examined. In control cells, PA induced a significant increase (25%) in active cell shortening and Ca(2+) transients. The phospholipase C (PLC) inhibitor, 2-nitro-4-carboxyphenyl N,N-diphenylcarbonate, blocked the positive inotropic action induced by PA, indicating that PA induces an increase in contractile activity and Ca(2+) transients through stimulation of PLC. Conversely, in failing cardiomyocytes there was a loss of PA-induced increase in active cell shortening and Ca(2+) transients. PA did not alter resting cell length. Both diastolic and systolic [Ca(2+)] were significantly elevated in the failing cardiomyocytes. In vitro assessment of the cardiac sarcolemmal (SL) PLC activity revealed that the impaired failing cardiomyocyte response to PA was associated with a diminished stimulation of SL PLC activity by PA. Our results identify an important defect in the PA-PLC signaling pathway in failing cardiomyocytes, which may have significant implications for the depressed contractile function during CHF. PMID:12504106

  18. Comparative cardiac contractile actions of six narcotic analgesics: morphine, meperidine, pentazocine, fentanyl, methadone and l-alpha-acetylmethadol (LAAM).

    PubMed

    Rendig, S V; Amsterdam, E A; Henderson, G L; Mason, D T

    1980-10-01

    Cardiac muscle contractile responses to six narcotic analgesics (morphine, meperidine, pentazocine, fentanyl, methadone and l-alpha-acetylmethadol), at concentrations from 10(-8) to 10(-4) M, both in the presence and absence of the narcotic antagonist, naloxone, were studied in the isolated, isometric cat right ventricular papillary muscle preparation. Measurements of maximum developed tension (T), maximum rate of tension development (dT/dt) and time to peak tension indicated that no major changes in contractile function occurred with any narcotic at concentrations of 10(-8) to 10(-6) M except for small but significant (P < .05) increases in all three parameters at 10(-6) M fentanyl, and small but significant increases in dT/dt at 10(-8) to 10(-6) M meperidine. At 10(-5) M narcotic, dT/dt was significantly elevated in meperidine-treated muscles (+7%), but significantly reduced in muscles exposed to pentazocine (-8%) or l-alpha-acetylmethadol (-11%). For all six narcotics, the 10(-4) M drug concentration resulted in depression of contractile function that was often associated with nonresponsiveness to electrical stimulation. Pretreatment of muscles with naloxone (10(-4) M) did not prevent this reduction of contractile performance except at the highest concentration (10(-4) M) of meperidine. Following removal of drug, contractile performance improved to varying degrees (recovery to 72-97% of control T), except in l-alpha-acetylmethadol-treated muscles, in which there was no recovery of T. Isoproterenol (0.8 X 10(-7) M) elicited a positive inotropic response whether administered in the presence of 10(-4) M narcotic or following narcotic removal. We conclude that narcotic analgesics in high concentrations exert a direct myocardial depressant effect which is not prevented by naloxone and therefore is not mediated by interaction with opiate receptors. Rather, several effects, including myocardial depression, its reversibility by both drug removal and isoproterenol and

  19. Time course analysis of mechanical ventilation-induced diaphragm contractile muscle dysfunction in the rat

    PubMed Central

    Corpeno, R; Dworkin, B; Cacciani, N; Salah, H; Bergman, H-M; Ravara, B; Vitadello, M; Gorza, L; Gustafson, A-M; Hedström, Y; Petersson, J; Feng, H-Z; Jin, J-P; Iwamoto, H; Yagi, N; Artemenko, K; Bergquist, J; Larsson, L

    2014-01-01

    Controlled mechanical ventilation (CMV) plays a key role in triggering the impaired diaphragm muscle function and the concomitant delayed weaning from the respirator in critically ill intensive care unit (ICU) patients. To date, experimental and clinical studies have primarily focused on early effects on the diaphragm by CMV, or at specific time points. To improve our understanding of the mechanisms underlying the impaired diaphragm muscle function in response to mechanical ventilation, we have performed time-resolved analyses between 6 h and 14 days using an experimental rat ICU model allowing detailed studies of the diaphragm in response to long-term CMV. A rapid and early decline in maximum muscle fibre force and preceding muscle fibre atrophy was observed in the diaphragm in response to CMV, resulting in an 85% reduction in residual diaphragm fibre function after 9–14 days of CMV. A modest loss of contractile proteins was observed and linked to an early activation of the ubiquitin proteasome pathway, myosin:actin ratios were not affected and the transcriptional regulation of myosin isoforms did not show any dramatic changes during the observation period. Furthermore, small angle X-ray diffraction analyses demonstrate that myosin can bind to actin in an ATP-dependent manner even after 9–14 days of exposure to CMV. Thus, quantitative changes in muscle fibre size and contractile proteins are not the dominating factors underlying the dramatic decline in diaphragm muscle function in response to CMV, in contrast to earlier observations in limb muscles. The observed early loss of subsarcolemmal neuronal nitric oxide synthase activity, onset of oxidative stress, intracellular lipid accumulation and post-translational protein modifications strongly argue for significant qualitative changes in contractile proteins causing the severely impaired residual function in diaphragm fibres after long-term mechanical ventilation. For the first time, the present study

  20. Autologous Mesenchymal Stem Cells Produce Concordant Improvements in Regional Function, Tissue Perfusion and Fibrotic Burden when Administered to Patients Undergoing Coronary Artery Bypass Grafting – The PROMETHEUS Trial

    PubMed Central

    Karantalis, Vasileios; DiFede, Darcy L.; Gerstenblith, Gary; Pham, Si; Symes, James; Zambrano, Juan Pablo; Fishman, Joel; Pattany, Pradip; McNiece, Ian; Conte, John; Schulman, Steven; Wu, Katherine; Shah, Ashish; Breton, Elayne; Davis-Sproul, Janice; Schwarz, Richard; Feigenbaum, Gary; Mushtaq, Muzammil; Suncion, Viky Y.; Lardo, Albert C.; Borrello, Ivan; Mendizabal, Adam; Karas, Tomer Z.; Byrnes, John; Lowery, Maureen; Heldman, Alan W.; Hare, Joshua M.

    2014-01-01

    Rationale While accumulating data support the efficacy of intramyocardial cell-based therapy to improve LV function in patients with chronic ischemic cardiomyopathy undergoing CABG, the underlying mechanism and impact of cell injection site remain controversial.Mesenchymal stem cells (MSCs) improve LV structure and function through several effects including: reducing fibrosis, neoangiogenesis and neomyogenesis. Objective To test the hypothesis that the impact on cardiac structure and function following intramyocardial injections of autologous MSCs results from a concordance of pro-recovery phenotypic effects. Methods and Results Six patients were injected with autologous MSCs into akinetic/hypokinetic myocardial territories not receiving bypass graft for clinical reasons. MRI was used to measure scar, perfusion, wall thickness and contractility at baseline, 3, 6 and 18 months and to compare structural and functional recovery in regions that received MSC injections alone, revascularization alone, or neither. A composite score of MRI variables was used to assess concordance of antifibrotic effects, perfusion, and contraction at different regions. After 18 months, subjects receiving MSCs exhibited increased LVEF (+9.4±1.7%, p=0.0002) and decreased scar mass (-47.5±8.1%; p<0.0001) compared to baseline. MSC-injected segments had concordant reduction in scar size, perfusion and contractile improvement (concordant score: 2.93±0.07), whereas revascularized (0.5±0.21) and non-treated segments (-0.07±0.34) demonstrated non-concordant changes (p<0.0001 vs. injected segments). Conclusions Intramyocardial injection of autologous MSCs into akinetic yet non-revascularized segments produces comprehensive regional functional restitution, which in turn drives improvement in global LV function. These findings, although inconclusive due to lack of placebo group, have important therapeutic and mechanistic hypothesis-generating implications. PMID:24565698

  1. Testosterone improves motor function in Parkinson's disease.

    PubMed

    Mitchell, E; Thomas, D; Burnet, R

    2006-01-01

    In Parkinson's disease (PD) there is increasing evidence that sex steroids such as estradiol and testosterone modulate, either as a positive or negative effect, the clinical expression of a variety of movement disorders involving the nigrostriatum. Testosterone deficiency is common in the older male population and has an increased prevalence in parkinsonian patients. Testosterone therapy has been shown to improve the non-motor symptoms of PD but evidence for a direct effect of testosterone on motor symptoms is lacking. This case report demonstrates a significant improvement in the resting tremor and fine motor control after testosterone administration in a parkinsonian patient with testosterone deficiency (1 nmol/L). Motor symptom change was shown by serial assessment of the patient's handwriting, self-reporting using the Unified Parkinson's Disease Rating Scale and measurement of resting tremor amplitude by an accelerometer. The improvement in motor symptoms correlated with serum testosterone levels. The use of testosterone replacement in those men with decreased levels may improve the motor symptoms as well as increase general wellbeing. PMID:16410216

  2. Neutron monitor yield function: New improved computations

    NASA Astrophysics Data System (ADS)

    Mishev, A. L.; Usoskin, I. G.; Kovaltsov, G. A.

    2013-06-01

    A ground-based neutron monitor (NM) is a standard tool to measure cosmic ray (CR) variability near Earth, and it is crucially important to know its yield function for primary CRs. Although there are several earlier theoretically calculated yield functions, none of them agrees with experimental data of latitude surveys of sea-level NMs, thus suggesting for an inconsistency. A newly computed yield function of the standard sea-level 6NM64 NM is presented here separately for primary CR protons and α-particles, the latter representing also heavier species of CRs. The computations have been done using the GEANT-4 PLANETOCOSMICS Monte-Carlo tool and a realistic curved atmospheric model. For the first time, an effect of the geometrical correction of the NM effective area, related to the finite lateral expansion of the CR induced atmospheric cascade, is considered, which was neglected in the previous studies. This correction slightly enhances the relative impact of higher-energy CRs (energy above 5-10 GeV/nucleon) in NM count rate. The new computation finally resolves the long-standing problem of disagreement between the theoretically calculated spatial variability of CRs over the globe and experimental latitude surveys. The newly calculated yield function, corrected for this geometrical factor, appears fully consistent with the experimental latitude surveys of NMs performed during three consecutive solar minima in 1976-1977, 1986-1987, and 1996-1997. Thus, we provide a new yield function of the standard sea-level NM 6NM64 that is validated against experimental data.

  3. Requirements for contractility in disordered cytoskeletal bundles

    NASA Astrophysics Data System (ADS)

    Lenz, Martin; Gardel, Margaret L.; Dinner, Aaron R.

    2012-03-01

    Actomyosin contractility is essential for biological force generation, and is well understood in highly organized structures such as striated muscle. Additionally, actomyosin bundles devoid of this organization are known to contract both in vivo and in vitro, which cannot be described by standard muscle models. To narrow down the search for possible contraction mechanisms in these systems, we investigate their microscopic symmetries. We show that contractile behavior requires non-identical motors that generate large-enough forces to probe the nonlinear elastic behavior of F-actin. This suggests a role for filament buckling in the contraction of these bundles, consistent with recent experimental results on reconstituted actomyosin bundles.

  4. Non-invasive technology that improves cardiac function after experimental myocardial infarction: Whole Body Periodic Acceleration (pGz).

    PubMed

    Uryash, Arkady; Bassuk, Jorge; Kurlansky, Paul; Altamirano, Francisco; Lopez, Jose R; Adams, Jose A

    2015-01-01

    Myocardial infarction (MI) may produce significant inflammatory changes and adverse ventricular remodeling leading to heart failure and premature death. Pharmacologic, stem cell transplantation, and exercise have not halted the inexorable rise in the prevalence and great economic costs of heart failure despite extensive investigations of such treatments. New therapeutic modalities are needed. Whole Body Periodic Acceleration (pGz) is a non-invasive technology that increases pulsatile shear stress to the endothelium thereby producing several beneficial cardiovascular effects as demonstrated in animal models, normal humans and patients with heart disease. pGz upregulates endothelial derived nitric oxide synthase (eNOS) and its phosphorylation (p-eNOS) to improve myocardial function in models of myocardial stunning and preconditioning. Here we test whether pGz applied chronically after focal myocardial infarction in rats improves functional outcomes from MI. Focal MI was produced by left coronary artery ligation. One day after ligation animals were randomized to receive daily treatments of pGz for four weeks (MI-pGz) or serve as controls (MI-CONT), with an additional group as non-infarction controls (Sham). Echocardiograms and invasive pressure volume loop analysis were carried out. Infarct transmurality, myocardial fibrosis, and markers of inflammatory and anti-inflammatory cytokines were determined along with protein analysis of eNOS, p-eNOS and inducible nitric oxide synthase (iNOS).At four weeks, survival was 80% in MI-pGz vs 50% in MI-CONT (p< 0.01). Ejection fraction and fractional shortening and invasive pressure volume relation indices of afterload and contractility were significantly better in MI-pGz. The latter where associated with decreased infarct transmurality and decreased fibrosis along with increased eNOS, p-eNOS. Additionally, MI-pGz had significantly lower levels of iNOS, inflammatory cytokines (IL-6, TNF-α), and higher level of anti

  5. Non-Invasive Technology That Improves Cardiac Function after Experimental Myocardial Infarction: Whole Body Periodic Acceleration (pGz)

    PubMed Central

    Kurlansky, Paul; Altamirano, Francisco; Lopez, Jose R.

    2015-01-01

    Myocardial infarction (MI) may produce significant inflammatory changes and adverse ventricular remodeling leading to heart failure and premature death. Pharmacologic, stem cell transplantation, and exercise have not halted the inexorable rise in the prevalence and great economic costs of heart failure despite extensive investigations of such treatments. New therapeutic modalities are needed. Whole Body Periodic Acceleration (pGz) is a non-invasive technology that increases pulsatile shear stress to the endothelium thereby producing several beneficial cardiovascular effects as demonstrated in animal models, normal humans and patients with heart disease. pGz upregulates endothelial derived nitric oxide synthase (eNOS) and its phosphorylation (p-eNOS) to improve myocardial function in models of myocardial stunning and preconditioning. Here we test whether pGz applied chronically after focal myocardial infarction in rats improves functional outcomes from MI. Focal MI was produced by left coronary artery ligation. One day after ligation animals were randomized to receive daily treatments of pGz for four weeks (MI-pGz) or serve as controls (MI-CONT), with an additional group as non-infarction controls (Sham). Echocardiograms and invasive pressure volume loop analysis were carried out. Infarct transmurality, myocardial fibrosis, and markers of inflammatory and anti-inflammatory cytokines were determined along with protein analysis of eNOS, p-eNOS and inducible nitric oxide synthase (iNOS).At four weeks, survival was 80% in MI-pGz vs 50% in MI-CONT (p< 0.01). Ejection fraction and fractional shortening and invasive pressure volume relation indices of afterload and contractility were significantly better in MI-pGz. The latter where associated with decreased infarct transmurality and decreased fibrosis along with increased eNOS, p-eNOS. Additionally, MI-pGz had significantly lower levels of iNOS, inflammatory cytokines (IL-6, TNF-α), and higher level of anti

  6. Improved association in a classical density functional theory for water.

    PubMed

    Krebs, Eric J; Schulte, Jeff B; Roundy, David

    2014-03-28

    We present a modification to our recently published statistical associating fluid theory-based classical density functional theory for water. We have recently developed and tested a functional for the averaged radial distribution function at contact of the hard-sphere fluid that is dramatically more accurate at interfaces than earlier approximations. We now incorporate this improved functional into the association term of our free energy functional for water, improving its description of hydrogen bonding. We examine the effect of this improvement by studying two hard solutes (a hard hydrophobic rod and a hard sphere) and a Lennard-Jones approximation of a krypton atom solute. The improved functional leads to a moderate change in the density profile and a large decrease in the number of hydrogen bonds broken in the vicinity of the hard solutes. We find an improvement of the partial radial distribution for a krypton atom in water when compared with experiment. PMID:24697459

  7. Improved association in a classical density functional theory for water

    SciTech Connect

    Krebs, Eric J.; Schulte, Jeff B.; Roundy, David

    2014-03-28

    We present a modification to our recently published statistical associating fluid theory-based classical density functional theory for water. We have recently developed and tested a functional for the averaged radial distribution function at contact of the hard-sphere fluid that is dramatically more accurate at interfaces than earlier approximations. We now incorporate this improved functional into the association term of our free energy functional for water, improving its description of hydrogen bonding. We examine the effect of this improvement by studying two hard solutes (a hard hydrophobic rod and a hard sphere) and a Lennard-Jones approximation of a krypton atom solute. The improved functional leads to a moderate change in the density profile and a large decrease in the number of hydrogen bonds broken in the vicinity of the hard solutes. We find an improvement of the partial radial distribution for a krypton atom in water when compared with experiment.

  8. Caveolin-3 Promotes a Vascular Smooth Muscle Contractile Phenotype

    PubMed Central

    Gutierrez-Pajares, Jorge L.; Iturrieta, Jeannette; Dulam, Vipin; Wang, Yu; Pavlides, Stephanos; Malacari, Gabriella; Lisanti, Michael P.; Frank, Philippe G.

    2015-01-01

    Epidemiological studies have demonstrated the importance of cardiovascular diseases in Western countries. Among the cell types associated with a dysfunctional vasculature, smooth muscle (SM) cells are believed to play an essential role in the development of these illnesses. Vascular SM cells are key regulators of the vascular tone and also have an important function in the development of atherosclerosis and restenosis. While in the normal vasculature, contractile SM cells are predominant, in atherosclerotic vascular lesions, synthetic cells migrate toward the neointima, proliferate, and synthetize extracellular matrix proteins. In the present study, we have examined the role of caveolin-3 in the regulation of SM cell phenotype. Caveolin-3 is expressed in vivo in normal arterial SM cells, but its expression appears to be lost in cultured SM cells. Our data show that caveolin-3 expression in the A7r5 SM cell line is associated with increased expression of contractility markers such as SM α-actin, SM myosin heavy chain but decreased expression of the synthetic phenotype markers such as p-Elk and Klf4. Moreover, we also show that caveolin-3 expression can reduce proliferation upon treatment with LDL or PDGF. Finally, we show that caveolin-3-expressing SM cells are less sensitive to apoptosis than control cells upon treatment with oxidized LDL. Taken together, our data suggest that caveolin-3 can regulate the phenotypic switch between contractile and synthetic SM cells. A better understanding of the factors regulating caveolin-3 expression and function in this cell type will permit the development of a better comprehension of the factors regulating SM function in atherosclerosis and restenosis. PMID:26664898

  9. Improving Density Functionals with Quantum Harmonic Oscillators

    NASA Astrophysics Data System (ADS)

    Tkatchenko, Alexandre

    2013-03-01

    Density functional theory (DFT) is the most widely used and successful approach for electronic structure calculations. However, one of the pressing challenges for DFT is developing efficient functionals that can accurately capture the omnipresent long-range electron correlations, which determine the structure and stability of many molecules and materials. Here we show that, under certain conditions, the problem of computing the long-range correlation energy of interacting electrons can be mapped to a system of coupled quantum harmonic oscillators (QHOs). The proposed model allows us to synergistically combine concepts from DFT, quantum chemistry, and the widely discussed random-phase approximation for the correlation energy. In the dipole limit, the interaction energy for a system of coupled QHOs can be calculated exactly, thereby leading to an efficient and accurate model for the many-body dispersion energy of complex molecules and materials. The studied examples include intermolecular binding energies, the conformational hierarchy of DNA structures, the geometry and stability of molecular crystals, and supramolecular host-guest complexes (A. Tkatchenko, R. A. DiStasio Jr., R. Car, M. Scheffler, Phys. Rev. Lett. 108, 236402 (2012); R. A. DiStasio Jr., A. von Lilienfeld, A. Tkatchenko, PNAS 109, 14791 (2012); A. Tkatchenko, D. Alfe, K. S. Kim, J. Chem. Theory and Comp. (2012), doi: 10.1021/ct300711r; A. Tkatchenko, A. Ambrosetti, R. A. DiStasio Jr., arXiv:1210.8343v1).

  10. The role of voltage-gated potassium channels in the regulation of mouse uterine contractility

    PubMed Central

    Smith, Ryan C; McClure, Marisa C; Smith, Margaret A; Abel, Peter W; Bradley, Michael E

    2007-01-01

    Background Uterine smooth muscle cells exhibit ionic currents that appear to be important in the control of uterine contractility, but how these currents might produce the changes in contractile activity seen in pregnant myometrium has not been established. There are conflicting reports concerning the role of voltage-gated potassium (Kv) channels and large-conductance, calcium-activated potassium (BK) channels in the regulation of uterine contractility. In this study we provide molecular and functional evidence for a role for Kv channels in the regulation of spontaneous contractile activity in mouse myometrium, and also demonstrate a change in Kv channel regulation of contractility in pregnant mouse myometrium. Methods Functional assays which evaluated the effects of channel blockers and various contractile agonists were accomplished by quantifying contractility of isolated uterine smooth muscle obtained from nonpregnant mice as well as mice at various stages of pregnancy. Expression of Kv channel proteins in isolated uterine smooth muscle was evaluated by Western blots. Results The Kv channel blocker 4-aminopyridine (4-AP) caused contractions in nonpregnant mouse myometrium (EC50 = 54 micromolar, maximal effect at 300 micromolar) but this effect disappeared in pregnant mice; similarly, the Kv4.2/Kv4.3 blocker phrixotoxin-2 caused contractions in nonpregnant, but not pregnant, myometrium. Contractile responses to 4-AP were not dependent upon nerves, as neither tetrodotoxin nor storage of tissues at room temperature significantly altered these responses, nor were responses dependent upon the presence of the endometrium. Spontaneous contractions and contractions in response to 4-AP did not appear to be mediated by BK, as the BK channel-selective blockers iberiotoxin, verruculogen, or tetraethylammonium failed to affect either spontaneous contractions or 4-AP-elicited responses. A number of different Kv channel alpha subunit proteins were found in isolated myometrium

  11. Sphincter Contractility After Muscle-Derived Stem Cells Autograft into the Cryoinjured Anal Sphincters of Rats

    PubMed Central

    Kang, Sung-Bum; Lee, Haet Nim; Lee, Ji Young; Park, Jun-Seok; Lee, Hye Seung

    2008-01-01

    Purpose This study was designed to determine whether the injection of muscle-derived stem cells into the anal sphincter can improve functional properties in a fecal incontinence rat model. Methods Cryoinjured rats were utilized as a fecal incontinence model. The gastrocnemius muscles of normal three-week-old female Sprague-Dawley rats were used for the purification of the muscle-derived stem cells. The experimental group was divided into three subgroups: normal control; cryoinjured; and muscle-derived stem cells (3 × 106 cells) injection group of cryoinjured rats. All groups were subsequently employed in contractility experiments using muscle strips from the anal sphincter, one week after preparation. Results Contractility in the cryoinjured group was significantly lower than in the control after treatment with acetylcholine and KCl. In the muscle-derived stem cells injection group, contraction amplitude was higher than in the cryoinjured group but not significantly (20.5 ± 21.3 vs. 17.3 ± 3.4 g per gram tissue, with acetylcholine (10−4 mol/l); 31 ± 14.2 vs. 18.4 ± 7.9 g per gram tissue, with KCl (10−4 mol/l)). PKH-26-labeled transplanted cells were detected in all of the grafted sphincters. Differentiated muscle masses stained positively for alpha smooth muscle actin and myosin heavy chain at the muscle-derived stem cells injection sites. Conclusions This is the first study reporting that autologous muscle-derived stem cell grafts may be a tool for improving anal sphincter function. PMID:18536965

  12. Sulforaphane is anticonvulsant and improves mitochondrial function.

    PubMed

    Carrasco-Pozo, Catalina; Tan, Kah Ni; Borges, Karin

    2015-12-01

    The nuclear factor erythroid 2-related factor 2 pathway (Nrf2) has been previously identified to protect the brain against various impacts. Here, we investigated the effect of the Nrf2 activator sulforaphane in various seizure models and hippocampal mitochondrial bioenergetics. We found that daily injections of sulforaphane for 5 days elevated the seizure thresholds to 6 Hz stimulation and fluorothyl-, but not pentylenetetrazole-induced tonic seizures and protected mice against pilocarpine-induced status epilepticus (SE). Also, sulforaphane increased the antioxidant defences within hippocampal formations and blood plasma. In addition, sulforaphane treatment reduced the extent of hippocampal lipid peroxidation 24 h post-SE and protected hippocampal mitochondria against SE-induced reduction in state 2 and uncoupler-stimulated state 3 respiration. SE-mediated partial loss of rotenone-sensitive and complex II-driven respiration was reduced, consistent with the enhanced activities of complexes I and II in sulforaphane-treated SE mice. In mitochondria isolated from both no SE and SE mice, sulforaphane increased state 3 respiration and respiration linked to ATP synthesis, which may contribute to its anticonvulsant and antioxidant effects by providing more ATP for cellular vital and protective functions. However, sulforaphane did not prevent SE-induced hippocampal cell death. In conclusion, sulforaphane and/or Nrf2 activation are viable anticonvulsant strategies, which are antioxidant and enhance mitochondrial function, especially the ability to produce ATP. Sulforaphane was anticonvulsant in two acute mouse models of epilepsy and protected mice against pilocarpine-induced status epilepticus (SE). We also found antioxidant effects of sulforaphane in mouse plasma and hippocampal formations, exhibited by increased catalase and superoxide dismutase (SOD) activity, as well as increased abilities of hippocampal mitochondria to produce ATP. These effects likely underlie

  13. Regulation of the uterine contractile apparatus and cytoskeleton

    PubMed Central

    Morgan, Kathleen G

    2007-01-01

    Parturition at term, the end stage of a successful pregnancy occurs as a result of powerful, co-ordinated and periodic contractions of uterine smooth muscle (myometrium). To occur in a propitious manner, a high degree of control over the activation of a myometrial cell is required. We review the molecular mechanisms and structural composition of myometrial cells that may contribute to their increased contractile capacity at term. We focus attention on pathways that lead to the activation of filamentous networks traditionally labeled ‘contractile’ or ‘cytoskeletal’ yet draw attention to the fact that functional discrimination between these systems is not absolute. PMID:17582796

  14. Quantifying esophagogastric junction contractility with a novel HRM topographic metric, the EGJ-Contractile Integral: normative values and preliminary evaluation in PPI non-responders

    PubMed Central

    Nicodème, Frédéric; Pipa-Muniz, Maria; Khanna, Kern; Kahrilas, Peter J.; Pandolfino, John E.

    2015-01-01

    Background Despite its obvious pathophysiological relevance, the clinical utility of measures of esophagogastric junction (EGJ) contractility is unsubstantiated. High-resolution manometry (HRM) may improve upon this with its inherent ability to integrate the magnitude of contractility over time and length of the EGJ. This study aimed to develop a novel HRM metric summarizing EGJ contractility and test its ability distinguish among subgroups of proton pump inhibitor non-responders (PPI-NRs). Methods 75 normal controls and 88 PPI-NRs were studied. All underwent HRM. PPI-NRs underwent pH-impedance monitoring on PPI therapy scored in terms of acid exposure, number of reflux events, and reflux-symptom correlation and grouped as meeting All Criteria, Some Criteria, or No Criteria of abnormality. Control HRM studies were used to establish normal values for candidate EGJ contractility metrics, which were then compared in their ability to differentiate among PPI-NR subgroups. Results The EGJ contractile integral (EGJ-CI), a metric integrating contractility across the EGJ for three respiratory cycles, best distinguished the All Criteria PPI-NR subgroup from controls and other PPI-NR subgroups. Normal values (median, [IQR]) for this measure were 39 mmHg-cm [25–55 mmHg-cm]. The correlation between the EGJ-CI and a previously proposed metric, the lower esophageal sphincter-pressure integral, that used a fixed 10s time frame and an atmospheric as opposed to gastric pressure reference was weak. Conclusion Among HRM metrics tested, the EGJ-CI was best in distinguishing PPI-NRs meeting All Criteria of abnormality on pH-impedance testing. Future prospective studies are required to explore its utility in management of broader groups of GERD patients. PMID:24460814

  15. [Subcellular basis of disorders of the contractile capacity of the heart in L-thyroxine-induced thyrotoxicosis].

    PubMed

    Karsanov, N V; Melashvili, N O; Khugashvili, Z G; Mamulashvili, L D; Azrumelashvili, M I; Khaindrava, G K; Kapanadze, R V

    1990-02-01

    In experiments on dogs, the authors examined the functional activity of three cardiomyocyte systems responsible for contraction-relaxation (the systems of contractile proteins, calcium transport and energy supply) in the dynamics of L-thyroxine-induced toxicosis. A fall in the capacity of the contractile protein system to generate energy and to perform was shown to play the leading role in decrease of myocardial reserve forces and reduction in cardiac contractility. There was a drop in the intensity of calcium transport through the membranes of the sarcoplasmic reticulum and mitochondria and a deficiency of the direct energy source for contraction only in the late period of the disease. PMID:2348627

  16. Nanosecond pulsed platelet-rich plasma (nsPRP) improves mechanical and electrical cardiac function following myocardial reperfusion injury.

    PubMed

    Hargrave, Barbara; Varghese, Frency; Barabutis, Nektarios; Catravas, John; Zemlin, Christian

    2016-02-01

    Ischemia and reperfusion (I/R) of the heart is associated with biochemical and ionic changes that result in cardiac contractile and electrical dysfunction. In rabbits, platelet-rich plasma activated using nanosecond pulsed electric fields (nsPRP) has been shown to improve left ventricular pumping. Here, we demonstrate that nsPRP causes a similar improvement in mouse left ventricular function. We also show that nsPRP injection recovers electrical activity even before reperfusion begins. To uncover the mechanism of nsPRP action, we studied whether the enhanced left ventricular function in nsPRP rabbit and mouse hearts was associated with increased expression of heat-shock proteins and altered mitochondrial function under conditions of oxidative stress. Mouse hearts underwent 30 min of global ischemia and 1 h of reperfusion in situ. Rabbit hearts underwent 30 min of ischemia in vivo and were reperfused for 14 days. Hearts treated with nsPRP expressed significantly higher levels of Hsp27 and Hsp70 compared to hearts treated with vehicle. Also, pretreatment of cultured H9c2 cells with nsPRP significantly enhanced the "spare respiratory capacity (SRC)" also referred to as "respiratory reserve capacity" and ATP production in response to the uncoupler FCCP. These results suggest a cardioprotective effect of nsPRP on the ischemic heart during reperfusion. PMID:26908713

  17. Architecture and Connectivity Govern Actin Network Contractility.

    PubMed

    Ennomani, Hajer; Letort, Gaëlle; Guérin, Christophe; Martiel, Jean-Louis; Cao, Wenxiang; Nédélec, François; De La Cruz, Enrique M; Théry, Manuel; Blanchoin, Laurent

    2016-03-01

    Actomyosin contractility plays a central role in a wide range of cellular processes, including the establishment of cell polarity, cell migration, tissue integrity, and morphogenesis during development. The contractile response is variable and depends on actomyosin network architecture and biochemical composition. To determine how this coupling regulates actomyosin-driven contraction, we used a micropatterning method that enables the spatial control of actin assembly. We generated a variety of actin templates and measured how defined actin structures respond to myosin-induced forces. We found that the same actin filament crosslinkers either enhance or inhibit the contractility of a network, depending on the organization of actin within the network. Numerical simulations unified the roles of actin filament branching and crosslinking during actomyosin contraction. Specifically, we introduce the concept of "network connectivity" and show that the contractions of distinct actin architectures are described by the same master curve when considering their degree of connectivity. This makes it possible to predict the dynamic response of defined actin structures to transient changes in connectivity. We propose that, depending on the connectivity and the architecture, network contraction is dominated by either sarcomeric-like or buckling mechanisms. More generally, this study reveals how actin network contractility depends on its architecture under a defined set of biochemical conditions. PMID:26898468

  18. Intestinal permeability and contractility in murine colitis.

    PubMed Central

    van Meeteren, M E; van Bergeijk, J D; van Dijk, A P; Tak, C J; Meijssen, M A; Zijlstra, F J

    1998-01-01

    We developed an in vitro organ bath method to measure permeability and contractility simultaneously in murine intestinal segments. To investigate whether permeability and contractility are correlated and influenced by mucosal damage owing to inflammation, BALB/c mice were exposed to a 10% dextran sulphate sodium (DSS) solution for 8 days to induce colitis. The effect of pharmacologically induced smooth muscle relaxation and contraction on permeability was tested in vitro. Regional permeability differences were observed in both control and 10% DSS-treated mice. Distal colon segments were less permeable to 3H-mannitol and 14C-PEG 400 molecules compared with proximal colon and ileum. Intestinal permeability in control vs. 10% DSS mice was not altered, although histologic inflammation score and IFN-gamma pro-inflammatory cytokine levels were significantly increased in proximal and distal colon. IL-1beta levels were enhanced in these proximal and distal segments, but not significantly different from controls. Any effect of pharmacologically induced contractility on intestinal permeability could not be observed. In conclusion, intestinal permeability and contractility are not correlated in this model of experimentally induced colitis in mice. Although simultaneous measurement in a physiological set-up is possible, this method has to be further validated. PMID:9705603

  19. Spontaneous Formation of a Globally Connected Contractile Network in a Microtubule-Motor System.

    PubMed

    Torisawa, Takayuki; Taniguchi, Daisuke; Ishihara, Shuji; Oiwa, Kazuhiro

    2016-07-26

    Microtubule (MT) networks play key roles in cell division, intracellular transport, and cell motility. These functions of MT networks occur through interactions between MTs and various associated proteins, notably motor proteins that bundle and slide MTs. Our objective in this study was to address the question of how motors determine the nature of MT networks. We conducted in vitro assays using homotetrameric kinesin Eg5, a motor protein involved in the formation and maintenance of the mitotic spindle. The mixing of Eg5 and MTs produced a range of spatiotemporal dynamics depending on the motor/filament ratio. Low motor/filament ratios produced globally connected static MT networks with sparsely distributed contractile active nodes (motor-accumulating points with radially extending MTs). Increasing the motor/filament ratio facilitated the linking of contractile active nodes and led to a global contraction of the network. When the motor/filament ratio was further increased, densely distributed active nodes formed local clusters and segmented the network into pieces with their strong contractile forces. Altering the properties of the motor through the use of chimeric Eg5, which has kinesin-1 heads, resulted in the generation of many isolated asters. These results suggest that the spatial distribution of contractile active nodes determines the dynamics of MT-motor networks. We then developed a coarse-grained model of MT-motor networks and identified two essential features for reproducing the experimentally observed patterns: an accumulation of motors that form the active nodes necessary to generate contractile forces, and a nonlinear dependency of contractile force on motor densities. Our model also enabled us to characterize the mechanical properties of the contractile network. Our study provides insight into how local motor-MT interactions generate the spatiotemporal dynamics of macroscopic network structures. PMID:27463139

  20. The contractile wall of the caput epididymidis in men affected by congenital or postinflammatory obstructive azoospermia.

    PubMed

    Pelliccione, Fiore; Cordeschi, Giuliana; Giuliani, Valeria; D'Abrizio, Piera; Necozione, Stefano; Negri, Luciano; Mancini, Mario; Sagone, Patrizia; Francavilla, Felice; Colpi, Giovanni Maria; Francavilla, Sandro

    2004-01-01

    The transport and storage of spermatozoa in the epididymis depend on the contractile activity of its tubular wall. It is not known what differences exist in the contractile wall of the human epididymis in cases of obstructive azoospermia. The contractile wall in the tubules of the caput epididymidis was analyzed by light microscopy and transmission electron microscopy in 10 azoospermic men, 5 with a bilateral congenital absence of vas deferens (CBAVD) and 5 with a bilateral postinflammatory congestive obstruction of the epididymis. Five specimens from the same region of the caput epididymidis, obtained from fertile men who had undergone an orchidectomy because of testicular cancer, served as controls. No differences were observed between congenital and congestive obstructions. The contractile wall in caput tubules proximal to the obstructed level was strongly thickened when compared with controls (62.98 +/- 5.84 micro; 80.82 +/- 7.72 micro vs 19.59 +/- 2.23 micro, respectively, for congestive and congenital obstructions vs controls; P <.0001 vs controls), and the spindle-shaped myoid cells, which formed the contractile wall in normal cases, were replaced by large smooth muscle cells (SMCs) that showed features of coexisting contractile and secretory functions. The former included crowded cytoplasmic bundles of thin myofilaments (5-6 nm in diameter) converging to a large number of dense bodies, numerous micropinocytotic vesicles of the plasma membrane, and a continuous cell basement membrane. The presence of a developed rough endoplasmic reticulum and a Golgi complex, associated with the accumulation of thick layers of pericellular basement membrane-like material and ground substance, was indicative of a secretory phenotype of SMCs. The increased mechanical forces on the epididymal wall upstream from the obstruction might eventually activate the differentiation of myoid cells into SMCs, leading to an altered physiology of the contractile wall that could have

  1. The contractome--a systems view of actomyosin contractility in non-muscle cells.

    PubMed

    Zaidel-Bar, Ronen; Zhenhuan, Guo; Luxenburg, Chen

    2015-06-15

    Actomyosin contractility is a highly regulated process that affects many fundamental biological processes in each and every cell in our body. In this Cell Science at a Glance article and the accompanying poster, we mined the literature and databases to map the contractome of non-muscle cells. Actomyosin contractility is involved in at least 49 distinct cellular functions that range from providing cell architecture to signal transduction and nuclear activity. Containing over 100 scaffolding and regulatory proteins, the contractome forms a highly complex network with more than 230 direct interactions between its components, 86 of them involving phosphorylation. Mapping these interactions, we identify the key regulatory pathways involved in the assembly of actomyosin structures and in activating myosin to produce contractile forces within non-muscle cells at the exact time and place necessary for cellular function. PMID:26021351

  2. Acoustic tweezing cytometry for live-cell subcellular modulation of intracellular cytoskeleton contractility

    PubMed Central

    Fan, Zhenzhen; Sun, Yubing; Di Chen; Tay, Donald; Chen, Weiqiang; Deng, Cheri X.; Fu, Jianping

    2013-01-01

    Mechanical forces are critical to modulate cell spreading, contractility, gene expression, and even stem cell differentiation. Yet, existing tools that can apply controllable subcellular forces to a large number of single cells simultaneously are still limited. Here we report a novel ultrasound tweezing cytometry utilizing ultrasound pulses to actuate functionalized lipid microbubbles covalently attached to single live cells to exert mechanical forces in the pN - nN range. Ultrasonic excitation of microbubbles could elicit a rapid and sustained reactive intracellular cytoskeleton contractile force increase in different adherent mechanosensitive cells. Further, ultrasound-mediated intracellular cytoskeleton contractility enhancement was dose-dependent and required an intact actin cytoskeleton as well as RhoA/ROCK signaling. Our results demonstrated the great potential of ultrasound tweezing cytometry technique using functionalized microbubbles as an actuatable, biocompatible, and multifunctional agent for biomechanical stimulations of cells. PMID:23846290

  3. Coordinated Regulation of Murine Cardiomyocyte Contractility by Nanomolar (−)-Epigallocatechin-3-Gallate, the Major Green Tea Catechin

    PubMed Central

    Feng, Wei; Hwang, Hyun Seok; Kryshtal, Dmytro O.; Yang, Tao; Padilla, Isela T.; Tiwary, Asheesh K.; Puschner, Birgit; Pessah, Isaac N.

    2012-01-01

    Green tea polyphenolic catechins exhibit biological activity in a wide variety of cell types. Although reports in the lay and scientific literature suggest therapeutic potential for improving cardiovascular health, the underlying molecular mechanisms of action remain unclear. Previous studies have implicated a wide range of molecular targets in cardiac muscle for the major green tea catechin, (−)-epigallocatechin-3-gallate (EGCG), but effects were observed only at micromolar concentrations of unclear clinical relevance. Here, we report that nanomolar concentrations of EGCG significantly enhance contractility of intact murine myocytes by increasing electrically evoked Ca2+ transients, sarcoplasmic reticulum (SR) Ca2+ content, and ryanodine receptor type 2 (RyR2) channel open probability. Voltage-clamp experiments demonstrate that 10 nM EGCG significantly inhibits the Na+-Ca2+ exchanger. Of importance, other Na+ and Ca2+ handling proteins such as Ca2+-ATPase, Na+-H+ exchanger, and Na+-K+-ATPase were not affected by EGCG ≤1 μM. Thus, nanomolar EGCG increases contractility in intact myocytes by coordinately modulating SR Ca2+ loading, RyR2-mediated Ca2+ release, and Na+-Ca2+ exchange. Inhibition of Na+-K+-ATPase activity probably contributes to the positive inotropic effects observed at EGCG concentrations >1 μM. These newly recognized actions of nanomolar and micromolar EGCG should be considered when the therapeutic and toxicological potential of green tea supplementation is evaluated and may provide a novel therapeutic strategy for improving contractile function in heart failure. PMID:22918967

  4. Cholesterol Depletion Alters Cardiomyocyte Subcellular Signaling and Increases Contractility

    PubMed Central

    McIntosh, Victoria J.; Abou Samra, Abdul B.; Mohammad, Ramzi M.; Lasley, Robert D.

    2016-01-01

    Membrane cholesterol levels play an important factor in regulating cell function. Sarcolemmal cholesterol is concentrated in lipid rafts and caveolae, which are flask-shaped invaginations of the plasma membrane. The scaffolding protein caveolin permits the enrichment of cholesterol in caveolae, and caveolin interactions with numerous proteins regulate their function. The purpose of this study was to determine whether acute reductions in cardiomyocyte cholesterol levels alter subcellular protein kinase activation, intracellular Ca2+ and contractility. Methods: Ventricular myocytes, isolated from adult Sprague Dawley rats, were treated with the cholesterol reducing agent methyl-β-cyclodextrin (MβCD, 5 mM, 1 hr, room temperature). Total cellular cholesterol levels, caveolin-3 localization, subcellular, ERK and p38 mitogen activated protein kinase (MAPK) signaling, contractility, and [Ca2+]i were assessed. Results: Treatment with MβCD reduced cholesterol levels by ~45 and shifted caveolin-3 from cytoskeleton and triton-insoluble fractions to the triton-soluble fraction, and increased ERK isoform phosphorylation in cytoskeletal, cytosolic, triton-soluble and triton-insoluble membrane fractions without altering their subcellular distributions. In contrast the primary effect of MβCD was on p38 subcellular distribution of p38α with little effect on p38 phosphorylation. Cholesterol depletion increased cardiomyocyte twitch amplitude and the rates of shortening and relaxation in conjunction with increased diastolic and systolic [Ca2+]i. Conclusions: These results indicate that acute reductions in membrane cholesterol levels differentially modulate basal cardiomyocyte subcellular MAPK signaling, as well as increasing [Ca2+]i and contractility. PMID:27441649

  5. Global Intracoronary Infusion of Allogeneic Cardiosphere-Derived Cells Improves Ventricular Function and Stimulates Endogenous Myocyte Regeneration throughout the Heart in Swine with Hibernating Myocardium

    PubMed Central

    Suzuki, Gen; Weil, Brian R.; Leiker, Merced M.; Ribbeck, Amanda E.; Young, Rebeccah F.; Cimato, Thomas R.; Canty, John M.

    2014-01-01

    Background Cardiosphere-derived cells (CDCs) improve ventricular function and reduce fibrotic volume when administered via an infarct-related artery using the “stop-flow” technique. Unfortunately, myocyte loss and dysfunction occur globally in many patients with ischemic and non-ischemic cardiomyopathy, necessitating an approach to distribute CDCs throughout the entire heart. We therefore determined whether global intracoronary infusion of CDCs under continuous flow improves contractile function and stimulates new myocyte formation. Methods and Results Swine with hibernating myocardium from a chronic LAD occlusion were studied 3-months after instrumentation (n = 25). CDCs isolated from myocardial biopsies were infused into each major coronary artery (∼33×106 icCDCs). Global icCDC infusion was safe and while ∼3% of injected CDCs were retained, they did not affect ventricular function or myocyte proliferation in normal animals. In contrast, four-weeks after icCDCs were administered to animals with hibernating myocardium, %LADWT increased from 23±6 to 51±5% (p<0.01). In diseased hearts, myocyte proliferation (phospho-histone-H3) increased in hibernating and remote regions with a concomitant increase in myocyte nuclear density. These effects were accompanied by reductions in myocyte diameter consistent with new myocyte formation. Only rare myocytes arose from sex-mismatched donor CDCs. Conclusions Global icCDC infusion under continuous flow is feasible and improves contractile function, regresses myocyte cellular hypertrophy and increases myocyte proliferation in diseased but not normal hearts. New myocytes arising via differentiation of injected cells are rare, implicating stimulation of endogenous myocyte regeneration as the primary mechanism of repair. PMID:25402428

  6. Sodium hydrogen exchanger as a mediator of hydrostatic edema induced intestinal contractile dysfunction

    PubMed Central

    Uray, Karen S.; Shah, Shinil K.; Radhakrishnan, Ravi S.; Jimenez, Fernando; Walker, Peter A.; Stewart, Randolph H.; Laine, Glen A.; Cox, Charles S.

    2010-01-01

    Background Resuscitation-induced intestinal edema is associated with early and profound mechanical changes in intestinal tissue. We hypothesize that the sodium hydrogen exchanger (NHE), a mechano-responsive ion channel, is a mediator of edema-induced intestinal contractile dysfunction. Methods An animal model of hydrostatic intestinal edema was utilized for all experiments. NHE isoforms 1-3 mRNA and protein were evaluated. Subsequently, the effects of NHE inhibition (with 5-(N-ethyl-N-isopropyl) amiloride (EIPA)) on wet to dry ratios, signal transduction and activator of transcription (STAT)-3, intestinal smooth muscle myosin light chain (MLC) phosphorylation, intestinal contractile activity, and intestinal transit were measured. Results NHE1-3 mRNA and protein levels were significantly increased in the small intestinal mucosa with the induction of intestinal edema. Administration of EIPA, an NHE inhibitor, attenuated validated markers of intestinal contractile dysfunction induced by edema as measured by decreased STAT-3 activation, increased MLC phosphorylation, improved intestinal contractile activity, and enhanced intestinal transit. Conclusion The mechano-responsive ion channel NHE may mediate edema-induced intestinal contractile dysfunction, possibly via a STAT-3 related mechanism. PMID:20553904

  7. Pentamidine rescues contractility and rhythmicity in a Drosophila model of myotonic dystrophy heart dysfunction

    PubMed Central

    Chakraborty, Mouli; Selma-Soriano, Estela; Magny, Emile; Couso, Juan Pablo; Pérez-Alonso, Manuel; Charlet-Berguerand, Nicolas; Artero, Ruben; Llamusi, Beatriz

    2015-01-01

    ABSTRACT Up to 80% of individuals with myotonic dystrophy type 1 (DM1) will develop cardiac abnormalities at some point during the progression of their disease, the most common of which is heart blockage of varying degrees. Such blockage is characterized by conduction defects and supraventricular and ventricular tachycardia, and carries a high risk of sudden cardiac death. Despite its importance, very few animal model studies have focused on the heart dysfunction in DM1. Here, we describe the characterization of the heart phenotype in a Drosophila model expressing pure expanded CUG repeats under the control of the cardiomyocyte-specific driver GMH5-Gal4. Morphologically, expression of 250 CUG repeats caused abnormalities in the parallel alignment of the spiral myofibrils in dissected fly hearts, as revealed by phalloidin staining. Moreover, combined immunofluorescence and in situ hybridization of Muscleblind and CUG repeats, respectively, confirmed detectable ribonuclear foci and Muscleblind sequestration, characteristic features of DM1, exclusively in flies expressing the expanded CTG repeats. Similarly to what has been reported in humans with DM1, heart-specific expression of toxic RNA resulted in reduced survival, increased arrhythmia, altered diastolic and systolic function, reduced heart tube diameters and reduced contractility in the model flies. As a proof of concept that the fly heart model can be used for in vivo testing of promising therapeutic compounds, we fed flies with pentamidine, a compound previously described to improve DM1 phenotypes. Pentamidine not only released Muscleblind from the CUG RNA repeats and reduced ribonuclear formation in the Drosophila heart, but also rescued heart arrhythmicity and contractility, and improved fly survival in animals expressing 250 CUG repeats. PMID:26515653

  8. In vivo visualization and quantification of collecting lymphatic vessel contractility using near-infrared imaging.

    PubMed

    Chong, Chloé; Scholkmann, Felix; Bachmann, Samia B; Luciani, Paola; Leroux, Jean-Christophe; Detmar, Michael; Proulx, Steven T

    2016-01-01

    Techniques to image lymphatic vessel function in either animal models or in the clinic are limited. In particular, imaging methods that can provide robust outcome measures for collecting lymphatic vessel function are sorely needed. In this study, we aimed to develop a method to visualize and quantify collecting lymphatic vessel function in mice, and to establish an in vivo system for evaluation of contractile agonists and antagonists using near-infrared fluorescence imaging. The flank collecting lymphatic vessel in mice was exposed using a surgical technique and a near-infrared tracer was infused into the inguinal lymph node. Collecting lymphatic vessel contractility and valve function could be easily visualized after the infusion. A diameter tracking method was established and the diameter of the vessel was found to closely correlate to near-infrared fluorescence signal. Phasic contractility measures of frequency and amplitude were established using an automated algorithm. The methods were validated by tracking the vessel response to topical application of a contractile agonist, prostaglandin F2α, and by demonstrating the potential of the technique for non-invasive evaluation of modifiers of lymphatic function. These new methods will enable high-resolution imaging and quantification of collecting lymphatic vessel function in animal models and may have future clinical applications. PMID:26960708

  9. In vivo visualization and quantification of collecting lymphatic vessel contractility using near-infrared imaging

    PubMed Central

    Chong, Chloé; Scholkmann, Felix; Bachmann, Samia B.; Luciani, Paola; Leroux, Jean-Christophe; Detmar, Michael; Proulx, Steven T.

    2016-01-01

    Techniques to image lymphatic vessel function in either animal models or in the clinic are limited. In particular, imaging methods that can provide robust outcome measures for collecting lymphatic vessel function are sorely needed. In this study, we aimed to develop a method to visualize and quantify collecting lymphatic vessel function in mice, and to establish an in vivo system for evaluation of contractile agonists and antagonists using near-infrared fluorescence imaging. The flank collecting lymphatic vessel in mice was exposed using a surgical technique and a near-infrared tracer was infused into the inguinal lymph node. Collecting lymphatic vessel contractility and valve function could be easily visualized after the infusion. A diameter tracking method was established and the diameter of the vessel was found to closely correlate to near-infrared fluorescence signal. Phasic contractility measures of frequency and amplitude were established using an automated algorithm. The methods were validated by tracking the vessel response to topical application of a contractile agonist, prostaglandin F2α, and by demonstrating the potential of the technique for non-invasive evaluation of modifiers of lymphatic function. These new methods will enable high-resolution imaging and quantification of collecting lymphatic vessel function in animal models and may have future clinical applications. PMID:26960708

  10. Scientific Benchmarks for Guiding Macromolecular Energy Function Improvement

    PubMed Central

    Leaver-Fay, Andrew; O’Meara, Matthew J.; Tyka, Mike; Jacak, Ron; Song, Yifan; Kellogg, Elizabeth H.; Thompson, James; Davis, Ian W.; Pache, Roland A.; Lyskov, Sergey; Gray, Jeffrey J.; Kortemme, Tanja; Richardson, Jane S.; Havranek, James J.; Snoeyink, Jack; Baker, David; Kuhlman, Brian

    2013-01-01

    Accurate energy functions are critical to macromolecular modeling and design. We describe new tools for identifying inaccuracies in energy functions and guiding their improvement, and illustrate the application of these tools to improvement of the Rosetta energy function. The feature analysis tool identifies discrepancies between structures deposited in the PDB and low energy structures generated by Rosetta; these likely arise from inaccuracies in the energy function. The optE tool optimizes the weights on the different components of the energy function by maximizing the recapitulation of a wide range of experimental observations. We use the tools to examine three proposed modifications to the Rosetta energy function: improving the unfolded state energy model (reference energies), using bicubic spline interpolation to generate knowledge based torisonal potentials, and incorporating the recently developed Dunbrack 2010 rotamer library (Shapovalov and Dunbrack, 2011). PMID:23422428

  11. Increased smooth muscle contractility in mice deficient for neuropilin 2.

    PubMed

    Bielenberg, Diane R; Seth, Abhishek; Shimizu, Akio; Pelton, Kristine; Cristofaro, Vivian; Ramachandran, Aruna; Zwaans, Bernadette M M; Chen, Cheng; Krishnan, Ramaswamy; Seth, Meetu; Huang, Lin; Takashima, Seiji; Klagsbrun, Michael; Sullivan, Maryrose P; Adam, Rosalyn M

    2012-08-01

    Neuropilins (NRPs) are transmembrane receptors that bind class 3 semaphorins and VEGF family members to regulate axon guidance and angiogenesis. Although expression of NRP1 by vascular smooth muscle cells (SMCs) has been reported, NRP function in smooth muscle (SM) in vivo is unexplored. Using Nrp2(+/LacZ) and Nrp2(+/gfp) transgenic mice, we observed robust and sustained expression of Nrp2 in the SM compartments of the bladder and gut, but no expression in vascular SM, skeletal muscle, or cardiac muscle. This expression pattern was recapitulated in vitro using primary human SM cell lines. Alterations in cell morphology after treatment of primary visceral SMCs with the NRP2 ligand semaphorin-3F (SEMA3F) were accompanied by inhibition of RhoA activity and myosin light chain phosphorylation, as well as decreased cytoskeletal stiffness. Ex vivo contractility testing of bladder muscle strips exposed to electrical stimulation or soluble agonists revealed enhanced tension generation of tissues from mice with constitutive or SM-specific knockout of Nrp2, compared with controls. Mice lacking Nrp2 also displayed increased bladder filling pressures, as assessed by cystometry in conscious mice. Together, these findings identify Nrp2 as a mediator of prorelaxant stimuli in SMCs and suggest a novel function for Nrp2 as a regulator of visceral SM contractility. PMID:22688055

  12. Human Engineered Heart Tissue: Analysis of Contractile Force.

    PubMed

    Mannhardt, Ingra; Breckwoldt, Kaja; Letuffe-Brenière, David; Schaaf, Sebastian; Schulz, Herbert; Neuber, Christiane; Benzin, Anika; Werner, Tessa; Eder, Alexandra; Schulze, Thomas; Klampe, Birgit; Christ, Torsten; Hirt, Marc N; Huebner, Norbert; Moretti, Alessandra; Eschenhagen, Thomas; Hansen, Arne

    2016-07-12

    Analyzing contractile force, the most important and best understood function of cardiomyocytes in vivo is not established in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM). This study describes the generation of 3D, strip-format, force-generating engineered heart tissues (EHT) from hiPSC-CM and their physiological and pharmacological properties. CM were differentiated from hiPSC by a growth factor-based three-stage protocol. EHTs were generated and analyzed histologically and functionally. HiPSC-CM in EHTs showed well-developed sarcomeric organization and alignment, and frequent mitochondria. Systematic contractility analysis (26 concentration-response curves) reveals that EHTs replicated canonical response to physiological and pharmacological regulators of inotropy, membrane- and calcium-clock mediators of pacemaking, modulators of ion-channel currents, and proarrhythmic compounds with unprecedented precision. The analysis demonstrates a high degree of similarity between hiPSC-CM in EHT format and native human heart tissue, indicating that human EHTs are useful for preclinical drug testing and disease modeling. PMID:27211213

  13. Implementing cell contractility in filament-based cytoskeletal models.

    PubMed

    Fallqvist, B

    2016-02-01

    Cells are known to respond over time to mechanical stimuli, even actively generating force at longer times. In this paper, a microstructural filament-based cytoskeletal network model is extended to incorporate this active response, and a computational study to assess the influence on relaxation behaviour was performed. The incorporation of an active response was achieved by including a strain energy function of contractile activity from the cross-linked actin filaments. A four-state chemical model and strain energy function was adopted, and generalisation to three dimensions and the macroscopic deformation field was performed by integration over the unit sphere. Computational results in MATLAB and ABAQUS/Explicit indicated an active cellular response over various time-scales, dependent on contractile parameters. Important features such as force generation and increasing cell stiffness due to prestress are qualitatively predicted. The work in this paper can easily be extended to encompass other filament-based cytoskeletal models as well. © 2016 Wiley Periodicals, Inc. PMID:26899417

  14. Ablation of SM22alpha decreases contractility and actin contents of mouse vascular smooth muscle.

    PubMed

    Zeidan, Asad; Swärd, Karl; Nordström, Ina; Ekblad, Eva; Zhang, Janet C L; Parmacek, Michael S; Hellstrand, Per

    2004-03-26

    The actin-binding protein SM22alpha marks contractile differentiation in smooth muscle, but its function is unknown. We tested its role in arterial contractility and stretch-sensitive vascular protein synthesis. Active stress in depolarised mesenteric resistance arteries and portal veins was reduced by 40% in SM22alpha(-/-) mice. Passive and active arterial circumference-force relationships were shifted leftwards, whereas alpha(1)-adrenergic responses were increased. Actin contents were 10-25% lower in vessels from SM22alpha(-/-) mice, but protein composition was otherwise similar. Synthesis of SM22alpha, calponin and alpha-actin, but not beta-actin, was sensitive to stretch. Ablation of SM22alpha did not affect stretch sensitivity of any of these proteins. Thus, SM22alpha plays a role in contractility, possibly by affecting actin filament organisation. PMID:15044015

  15. Dual gene therapy with SERCA1 and Kir2.1 abbreviates excitation without suppressing contractility

    PubMed Central

    Ennis, Irene L.; Li, Ronald A.; Murphy, Anne M.; Marbán, Eduardo; Nuss, H. Bradley

    2002-01-01

    Heart failure is characterized by depressed contractility and delayed repolarization. The latter feature predisposes the failing heart to ventricular arrhythmias and represents a logical target for gene therapy. Unfortunately, unopposed correction of the delay in repolarization will decrease the time available for calcium cycling during each heartbeat, potentially aggravating the depression of contractility. Here we describe the development and application of a novel gene therapy strategy designed to abbreviate excitation without depressing contraction. The calcium ATPase SERCA1 was coexpressed with the potassium channel Kir2.1 in guinea pig hearts. Myocytes from the hearts had bigger calcium transients and shorter action potentials. In vivo, repolarization was abbreviated, but contractile function remained unimpaired. Dual gene therapy of the sort described here can be generalized to exploit opposing or synergistic therapeutic principles to achieve a tailored phenotype. PMID:11827999

  16. Contractile and electrical properties of sternohyoid muscle in streptozotocin diabetic rats.

    PubMed

    McGuire, M; Dumbleton, M; MacDermott, M; Bradford, A

    2001-03-01

    1. The effects of diabetes on the electrical and contractile function of skeletal muscle are variable, depending on muscle fibre type distribution. The muscles of the upper airway have a characteristic fibre distribution that differs from previously studied muscles, but the effects of diabetes on upper airway muscle function are unknown. Normally, contraction of upper airway muscles, such as the sternohyoids, dilates and/or stabilizes the upper airway, thereby preventing its collapse. Diabetes is associated with obstructive sleep apnoea in which there is collapse of the upper airway due to failure of the upper airway musculature to maintain airway patency. Therefore, the purpose of the present study was to determine the effects of diabetes on the electrical and contractile characteristics of upper airway muscle. 2. Rats were treated with vehicle (sodium citrate buffer; pH 4.5) or with streptozotocin to induce diabetes, confirmed by the presence of hyperglycaemia, and the contractile and electrical properties of the sternohyoid were compared in these two groups. Isometric contractile properties and membrane potentials were determined in isolated sternohyoid muscles in physiological saline solution at 25 degrees C. 3. Streptozotocin had no effect on sternohyoid muscle fatigue, the tension-frequency relationship or membrane potentials, but did increase contraction time, half-relaxation time, twitch tension and tetanic tension. 4. Streptozotocin-induced diabetes has no effect on sternohyoid muscle fatigue or the tension-frequency relationship, but does reduce contractile kinetics and increases force generation. These effects are not due to changes in resting membrane potential. These data are evidence that the association of sleep apnoea and diabetes is not due to effects on upper airway muscle contractile properties. PMID:11207673

  17. Elastomeric contractile actuators for hand rehabilitation splints

    NASA Astrophysics Data System (ADS)

    Carpi, Federico; Mannini, Andrea; De Rossi, Danilo

    2008-03-01

    The significant electromechanical performances typically shown by dielectric elastomer actuators make this polymer technology particularly attractive for possible active orthoses for rehabilitation. Folded contractile actuators made of dielectric elastomers were recently described as a simple configuration, suitable to easily implement linear contractile devices. This paper describes an application of folded actuators for so-called hand splints: they consist of orthotic systems for hand rehabilitation. The dynamic versions of the state-of-the-art splints typically include elastic bands, which exert a passive elastic resistance to voluntary elongations of one or more fingers. In order to provide such splints with the possibility of electrically modulating the compliance of the resistive elements, the substitution of the passive elastic bands with the contractile actuators is here described. The electrical activation of the actuators is used to vary the compliance of the system; this enables modulations of the force that acts as an antagonist to voluntary finger movements, according to programmable rehabilitation exercises. The paper reports results obtained from the first prototype implementations of such a type of system.

  18. Contractile network models for adherent cells.

    PubMed

    Guthardt Torres, P; Bischofs, I B; Schwarz, U S

    2012-01-01

    Cells sense the geometry and stiffness of their adhesive environment by active contractility. For strong adhesion to flat substrates, two-dimensional contractile network models can be used to understand how force is distributed throughout the cell. Here we compare the shape and force distribution for different variants of such network models. In contrast to Hookean networks, cable networks reflect the asymmetric response of biopolymers to tension versus compression. For passive networks, contractility is modeled by a reduced resting length of the mechanical links. In actively contracting networks, a constant force couple is introduced into each link in order to model contraction by molecular motors. If combined with fixed adhesion sites, all network models lead to invaginated cell shapes, but only actively contracting cable networks lead to the circular arc morphology typical for strongly adhering cells. In this case, shape and force distribution are determined by local rather than global determinants and thus are suited to endow the cell with a robust sense of its environment. We also discuss nonlinear and adaptive linker mechanics as well as the relation to tissue shape. PMID:22400597

  19. Contractile network models for adherent cells

    NASA Astrophysics Data System (ADS)

    Guthardt Torres, P.; Bischofs, I. B.; Schwarz, U. S.

    2012-01-01

    Cells sense the geometry and stiffness of their adhesive environment by active contractility. For strong adhesion to flat substrates, two-dimensional contractile network models can be used to understand how force is distributed throughout the cell. Here we compare the shape and force distribution for different variants of such network models. In contrast to Hookean networks, cable networks reflect the asymmetric response of biopolymers to tension versus compression. For passive networks, contractility is modeled by a reduced resting length of the mechanical links. In actively contracting networks, a constant force couple is introduced into each link in order to model contraction by molecular motors. If combined with fixed adhesion sites, all network models lead to invaginated cell shapes, but only actively contracting cable networks lead to the circular arc morphology typical for strongly adhering cells. In this case, shape and force distribution are determined by local rather than global determinants and thus are suited to endow the cell with a robust sense of its environment. We also discuss nonlinear and adaptive linker mechanics as well as the relation to tissue shape.

  20. Walnuts improve neuronal and behavioral function in aging

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction Walnuts are rich in polyunsaturated fatty acids (PUFAs) and polyphenols which have been shown to improve neurochemical and behavioral function. Objectives This study investigated the mechanisms associated with age-related behavioral improvements in rats fed diets supplemented with walnu...

  1. A Novel Method for Quantifying Smooth Regional Variations in Myocardial Contractility Within an Infarcted Human Left Ventricle Based on Delay-Enhanced Magnetic Resonance Imaging.

    PubMed

    Genet, Martin; Chuan Lee, Lik; Ge, Liang; Acevedo-Bolton, Gabriel; Jeung, Nick; Martin, Alastair; Cambronero, Neil; Boyle, Andrew; Yeghiazarians, Yerem; Kozerke, Sebastian; Guccione, Julius M

    2015-08-01

    Heart failure is increasing at an alarming rate, making it a worldwide epidemic. As the population ages and life expectancy increases, this trend is not likely to change. Myocardial infarction (MI)-induced adverse left ventricular (LV) remodeling is responsible for nearly 70% of heart failure cases. The adverse remodeling process involves an extension of the border zone (BZ) adjacent to an MI, which is normally perfused but shows myofiber contractile dysfunction. To improve patient-specific modeling of cardiac mechanics, we sought to create a finite element model of the human LV with BZ and MI morphologies integrated directly from delayed-enhancement magnetic resonance (DE-MR) images. Instead of separating the LV into discrete regions (e.g., the MI, BZ, and remote regions) with each having a homogeneous myocardial material property, we assumed a functional relation between the DE-MR image pixel intensity and myocardial stiffness and contractility--we considered a linear variation of material properties as a function of DE-MR image pixel intensity, which is known to improve the accuracy of the model's response. The finite element model was then calibrated using measurements obtained from the same patient--namely, 3D strain measurements-using complementary spatial modulation of magnetization magnetic resonance (CSPAMM-MR) images. This led to an average circumferential strain error of 8.9% across all American Heart Association (AHA) segments. We demonstrate the utility of our method for quantifying smooth regional variations in myocardial contractility using cardiac DE-MR and CSPAMM-MR images acquired from a 78-yr-old woman who experienced an MI approximately 1 yr prior. We found a remote myocardial diastolic stiffness of C(0) = 0.102 kPa, and a remote myocardial contractility of T(max) = 146.9 kPa, which are both in the range of previously published normal human values. Moreover, we found a normalized pixel intensity range of 30% for the BZ, which is consistent with

  2. Improved variational wave functions for few-body nuclei

    SciTech Connect

    Wiringa, R.B.; Arriaga, A.; Pandharipande, V.R.

    1995-08-01

    We continued to work on improvements to our variational wave functions for use in Monte Carlo calculations of few-body nuclei. These trial functions include central, spin, isospin, tensor, and spin-orbit two-body correlations and three-body correlations for the three-nucleon potential. In the last two years we studied a variety of extra three-body correlations. Our search for possible forms was guided by comparisons made with 34-channel Faddeev wave functions provided by the Los Alamos-Iowa group. The new trial functions reduce the discrepancy with exact Faddeev calculations in {sup 3}H and Green`s Function Monte Carlo (GFMC) calculations in {sup 4}He by about 40%. This work is now being written up for publication. We hope to use similar comparisons with GFMC calculations in the six-body nuclei to find further improvements for the light p-shell nuclei, where the variational wave functions are not as good.

  3. Physiological response of cardiac tissue to bisphenol a: alterations in ventricular pressure and contractility

    PubMed Central

    Brooks, Daina; Chandra, Akhil; Jaimes, Rafael; Sarvazyan, Narine; Kay, Matthew

    2015-01-01

    Biomonitoring studies have indicated that humans are routinely exposed to bisphenol A (BPA), a chemical that is commonly used in the production of polycarbonate plastics and epoxy resins. Epidemiological studies have shown that BPA exposure in humans is associated with cardiovascular disease; however, the direct effects of BPA on cardiac physiology are largely unknown. Previously, we have shown that BPA exposure slows atrioventricular electrical conduction, decreases epicardial conduction velocity, and prolongs action potential duration in excised rat hearts. In the present study, we tested if BPA exposure also adversely affects cardiac contractile performance. We examined the impact of BPA exposure level, sex, and pacing rate on cardiac contractile function in excised rat hearts. Hearts were retrogradely perfused at constant pressure and exposed to 10−9-10−4 M BPA. Left ventricular developed pressure and contractility were measured during sinus rhythm and during pacing (5, 6.5, and 9 Hz). Ca2+ transients were imaged from whole hearts and from neonatal rat cardiomyocyte layers. During sinus rhythm in female hearts, BPA exposure decreased left ventricular developed pressure and inotropy in a dose-dependent manner. The reduced contractile performance was exacerbated at higher pacing rates. BPA-induced effects on contractile performance were also observed in male hearts, albeit to a lesser extent. Exposure to BPA altered Ca2+ handling within whole hearts (reduced diastolic and systolic Ca2+ transient potentiation) and neonatal cardiomyocytes (reduced Ca2+ transient amplitude and prolonged Ca2+ transient release time). In conclusion, BPA exposure significantly impaired cardiac performance in a dose-dependent manner, having a major negative impact upon electrical conduction, intracellular Ca2+ handing, and ventricular contractility. PMID:25980024

  4. Superoxide scavengers augment contractile but not energetic responses to hypoxia in rat diaphragm.

    PubMed

    Wright, V P; Klawitter, P F; Iscru, D F; Merola, A J; Clanton, T L

    2005-05-01

    Acute exposure to severe hypoxia depresses contractile function and induces adaptations in skeletal muscle that are only partially understood. Previous studies have demonstrated that antioxidants (AOXs) given during hypoxia partially protect contractile function, but this has not been a universal finding. This study confirms that specific AOXs, known to act primarily as superoxide scavengers, protect contractile function in severe hypoxia. Furthermore, the hypothesis is tested that the mechanism of protection involves preservation of high-energy phosphates (ATP, creatine phosphate) and reductions of P(i). Rat diaphragm muscle strips were treated with AOXs and subjected to 30 min of hypoxia. Contractile function was examined by using twitch and tetanic stimulations and the degree of elevation in passive force occurring during hypoxia (contracture). High-energy phosphates were measured at the end of 30-min hypoxia exposure. Treatment with the superoxide scavengers 4,5-dihydroxy-1,3-benzenedisulfonic acid (Tiron, 10 mM) or Mn(III)tetrakis(1-methyl-4-pyridyl) porphyrin pentachloride (50 microM) suppressed contracture during hypoxia and protected maximum tetanic force. N-acetylcysteine (10 or 18 mM) had no influence on tetanic force production. Contracture during hypoxia without AOXs was also shown to be dependent on the extracellular Ca(2+) concentration. Although hypoxia resulted in only small reductions in ATP concentration, creatine phosphate concentration was decreased to approximately 10% of control. There were no consistent influences of the AOX treatments on high-energy phosphates during hypoxia. The results demonstrate that superoxide scavengers can protect contractile function and reduce contracture in hypoxia through a mechanism that does not involve preservation of high-energy phosphates. PMID:15640388

  5. Passive hind-limb cycling improves cardiac function and reduces cardiovascular disease risk in experimental spinal cord injury

    PubMed Central

    West, Christopher R; Crawford, Mark A; Poormasjedi-Meibod, Malihe-Sadat; Currie, Katharine D; Fallavollita, Andre; Yuen, Violet; McNeill, John H; Krassioukov, Andrei V

    2014-01-01

    Spinal cord injury (SCI) causes altered autonomic control and severe physical deconditioning that converge to drive maladaptive cardiac remodelling. We used a clinically relevant experimental model to investigate the cardio-metabolic responses to SCI and to establish whether passive hind-limb cycling elicits a cardio-protective effect. Initially, 21 male Wistar rats were evenly assigned to three groups: uninjured control (CON), T3 complete SCI (SCI) or T3 complete SCI plus passive hind-limb cycling (SCI-EX; 2 × 30 min day−1, 5 days week−1 for 4 weeks beginning 6 days post-SCI). On day 32, cardio-metabolic function was assessed using in vivo echocardiography, ex vivo working heart assessments, cardiac histology/molecular biology and blood lipid profiles. Twelve additional rats (n = 6 SCI and n = 6 SCI-EX) underwent in vivo echocardiography and basal haemodynamic assessments pre-SCI and at days 7, 14 and 32 post-SCI to track temporal cardiovascular changes. Compared with CON, SCI exhibited a rapid and sustained reduction in left ventricular dimensions and function that ultimately manifested as reduced contractility, increased myocardial collagen deposition and an up-regulation of transforming growth factor beta-1 (TGFβ1) and mothers against decapentaplegic homolog 3 (Smad3) mRNA. For SCI-EX, the initial reduction in left ventricular dimensions and function at day 7 post-SCI was completely reversed by day 32 post-SCI, and there were no differences in myocardial contractility between SCI-EX and CON. Collagen deposition was similar between SCI-EX and CON. TGFβ1 and Smad3 were down-regulated in SCI-EX. Blood lipid profiles were improved in SCI-EX versus SCI. We provide compelling novel evidence that passive hind-limb cycling prevents cardiac dysfunction and reduces cardiovascular disease risk in experimental SCI. PMID:24535438

  6. Text Mining Improves Prediction of Protein Functional Sites

    PubMed Central

    Cohn, Judith D.; Ravikumar, Komandur E.

    2012-01-01

    We present an approach that integrates protein structure analysis and text mining for protein functional site prediction, called LEAP-FS (Literature Enhanced Automated Prediction of Functional Sites). The structure analysis was carried out using Dynamics Perturbation Analysis (DPA), which predicts functional sites at control points where interactions greatly perturb protein vibrations. The text mining extracts mentions of residues in the literature, and predicts that residues mentioned are functionally important. We assessed the significance of each of these methods by analyzing their performance in finding known functional sites (specifically, small-molecule binding sites and catalytic sites) in about 100,000 publicly available protein structures. The DPA predictions recapitulated many of the functional site annotations and preferentially recovered binding sites annotated as biologically relevant vs. those annotated as potentially spurious. The text-based predictions were also substantially supported by the functional site annotations: compared to other residues, residues mentioned in text were roughly six times more likely to be found in a functional site. The overlap of predictions with annotations improved when the text-based and structure-based methods agreed. Our analysis also yielded new high-quality predictions of many functional site residues that were not catalogued in the curated data sources we inspected. We conclude that both DPA and text mining independently provide valuable high-throughput protein functional site predictions, and that integrating the two methods using LEAP-FS further improves the quality of these predictions. PMID:22393388

  7. Lipid emulsion rapidly restores contractility in stunned mouse cardiomyocytes: A comparison with therapeutic hypothermia

    PubMed Central

    Li, Jing; Fettiplace, Michael; Sy-Jou, Chen; Steinhorn, Benjamin; Shao, Zuohui; Zhu, Xiangdong; Li, Changqing; Harty, Shaun; Weinberg, Guy; Vanden Hoek, Terry L.

    2014-01-01

    Objective Cooling following cardiac arrest can improve survival significantly. However, delays in achieving target temperature may decrease the overall benefits of cooling. Here we test whether lipid emulsion, a clinically approved drug reported to exert cardioprotection, can rescue heart contractility in the setting of delayed cooling in stunned mouse cardiomyocytes. Design Cell culture study Setting Academic research laboratory Subjects Cardiomyocytes isolated from 1–2-day old C57BL6 mice Interventions Cardiomyocytes were exposed to 30 minutes of ischemia followed by 90 minutes reperfusion and 10 minutes isoproterenol with nine interventions: 1) no additional treatment; 2) intra-ischemic cooling at 32°C initiated 10 min prior to reperfusion; 3) delayed cooling started 20 minutes after reperfusion; 4) lipid emulsion + delayed cooling; 5) lipid emulsion (0.25%) administered at reperfusion; 6) lipid emulsion + intra-ischemic cooling; 7) delayed lipid emulsion; 8) lipid emulsion + delayed cooling + Akt inhibitor (API-2, 10 μM) and 9) lipid emulsion + delayed cooling + Erk inhibitor (U0126, 10 μM). Inhibitors were given to cells 1 h prior to ischemia. Measurements and Main Results Contractility was recorded by real-time phase-contrast imaging and analyzed with pulse image velocimetry in MATLAB. Ischemia diminished cell contraction. The cardioprotective effect of cooling was diminished when delayed but was rescued by lipid emulsion. Further, lipid emulsion on its own improved recovery of the contractility to an equal extent as intra-ischemic cooling. However, co-treatment of lipid emulsion and intra-ischemic cooling did not further improve the recovery compared to either treatment alone. Moreover, Akt and Erk inhibitors blocked lipid emulsion-induced protection. Conclusion Lipid emulsion improved contractility and rescued contractility in the context of delayed cooling. This protective effect required Akt and Erk signaling. Lipid emulsion might serve as a

  8. Cell stiffness, contractile stress and the role of extracellular matrix

    SciTech Connect

    An, Steven S.; Kim, Jina; Ahn, Kwangmi; Trepat, Xavier; Drake, Kenneth J.; Kumar, Sarvesh; Ling, Guoyu; Purington, Carolyn; Rangasamy, Tirumalai; Kensler, Thomas W.; Mitzner, Wayne; Fredberg, Jeffrey J.; Biswal, Shyam

    2009-05-15

    Here we have assessed the effects of extracellular matrix (ECM) composition and rigidity on mechanical properties of the human airway smooth muscle (ASM) cell. Cell stiffness and contractile stress showed appreciable changes from the most relaxed state to the most contracted state: we refer to the maximal range of these changes as the cell contractile scope. The contractile scope was least when the cell was adherent upon collagen V, followed by collagen IV, laminin, and collagen I, and greatest for fibronectin. Regardless of ECM composition, upon adherence to increasingly rigid substrates, the ASM cell positively regulated expression of antioxidant genes in the glutathione pathway and heme oxygenase, and disruption of a redox-sensitive transcription factor, nuclear erythroid 2 p45-related factor (Nrf2), culminated in greater contractile scope. These findings provide biophysical evidence that ECM differentially modulates muscle contractility and, for the first time, demonstrate a link between muscle contractility and Nrf2-directed responses.

  9. Cytoskeletal Role in the Contractile Dysfunction of Hypertrophied Myocardium

    NASA Astrophysics Data System (ADS)

    Tsutsui, Hiroyuki; Ishihara, Kazuaki; Cooper, George

    1993-04-01

    Cardiac hypertrophy in response to systolic pressure loading frequently results in contractile dysfunction of unknown cause. In the present study, pressure loading increased the microtubule component of the cardiac muscle cell cytoskeleton, which was responsible for the cellular contractile dysfunction observed. The linked microtubule and contractile abnormalities were persistent and thus may have significance for the deterioration of initially compensatory cardiac hypertrophy into congestive heart failure.

  10. Regulation of tissue morphodynamics: an important role for actomyosin contractility

    PubMed Central

    Siedlik, Michael J.; Nelson, Celeste M.

    2015-01-01

    Forces arising from contractile actomyosin filaments help shape tissue form during morphogenesis. Developmental events that result from actomyosin contractility include tissue elongation, bending, budding, and collective migration. Here, we highlight recent insights into these morphogenetic processes from the perspective of actomyosin contractility as a key regulator. Emphasis is placed on a range of results obtained through live imaging, culture, and computational methods. Combining these approaches in the future has the potential to generate a robust, quantitative understanding of tissue morphodynamics. PMID:25748251

  11. Validation of an in vitro contractility assay using canine ventricular myocytes

    SciTech Connect

    Harmer, A.R. Abi-Gerges, N.; Morton, M.J.; Pullen, G.F.; Valentin, J.P.; Pollard, C.E.

    2012-04-15

    Measurement of cardiac contractility is a logical part of pre-clinical safety assessment in a drug discovery project, particularly if a risk has been identified or is suspected based on the primary- or non-target pharmacology. However, there are limited validated assays available that can be used to screen several compounds in order to identify and eliminate inotropic liability from a chemical series. We have therefore sought to develop an in vitro model with sufficient throughput for this purpose. Dog ventricular myocytes were isolated using a collagenase perfusion technique and placed in a perfused recording chamber on the stage of a microscope at ∼ 36 °C. Myocytes were stimulated to contract at a pacing frequency of 1 Hz and a digital, cell geometry measurement system (IonOptix™) was used to measure sarcomere shortening in single myocytes. After perfusion with vehicle (0.1% DMSO), concentration–effect curves were constructed for each compound in 4–30 myocytes taken from 1 or 2 dog hearts. The validation test-set was 22 negative and 8 positive inotropes, and 21 inactive compounds, as defined by their effect in dog, cynolomolgous monkey or humans. By comparing the outcome of the assay to the known in vivo contractility effects, the assay sensitivity was 81%, specificity was 75%, and accuracy was 78%. With a throughput of 6–8 compounds/week from 1 cell isolation, this assay may be of value to drug discovery projects to screen for direct contractility effects and, if a hazard is identified, help identify inactive compounds. -- Highlights: ► Cardiac contractility is an important physiological function of the heart. ► Assessment of contractility is a logical part of pre-clinical drug safety testing. ► There are limited validated assays that predict effects of compounds on contractility. ► Using dog myocytes, we have developed an in vitro cardiac contractility assay. ► The assay predicted the in vivo contractility with a good level of accuracy.

  12. The contractile vacuole as a key regulator of cellular water flow in Chlamydomonas reinhardtii.

    PubMed

    Komsic-Buchmann, Karin; Wöstehoff, Luisa; Becker, Burkhard

    2014-11-01

    Most freshwater flagellates use contractile vacuoles (CVs) to expel excess water. We have used Chlamydomonas reinhardtii as a green model system to investigate CV function during adaptation to osmotic changes in culture medium. We show that the contractile vacuole in Chlamydomonas is regulated in two different ways. The size of the contractile vacuoles increases during cell growth, with the contraction interval strongly depending on the osmotic strength of the medium. In contrast, there are only small fluctuations in cytosolic osmolarity and plasma membrane permeability. Modeling of the CV membrane permeability indicates that only a small osmotic gradient is necessary for water flux into the CV, which most likely is facilitated by the aquaporin major intrinsic protein 1 (MIP1). We show that MIP1 is localized to the contractile vacuole, and that the expression rate and protein level of MIP1 exhibit only minor fluctuations under different osmotic conditions. In contrast, SEC6, a protein of the exocyst complex that is required for the water expulsion step, and a dynamin-like protein are upregulated under strong hypotonic conditions. The overexpression of a CreMIP1-GFP construct did not change the physiology of the CV. The functional implications of these results are discussed. PMID:25217463

  13. The Contractile Vacuole as a Key Regulator of Cellular Water Flow in Chlamydomonas reinhardtii

    PubMed Central

    Komsic-Buchmann, Karin; Wöstehoff, Luisa

    2014-01-01

    Most freshwater flagellates use contractile vacuoles (CVs) to expel excess water. We have used Chlamydomonas reinhardtii as a green model system to investigate CV function during adaptation to osmotic changes in culture medium. We show that the contractile vacuole in Chlamydomonas is regulated in two different ways. The size of the contractile vacuoles increases during cell growth, with the contraction interval strongly depending on the osmotic strength of the medium. In contrast, there are only small fluctuations in cytosolic osmolarity and plasma membrane permeability. Modeling of the CV membrane permeability indicates that only a small osmotic gradient is necessary for water flux into the CV, which most likely is facilitated by the aquaporin major intrinsic protein 1 (MIP1). We show that MIP1 is localized to the contractile vacuole, and that the expression rate and protein level of MIP1 exhibit only minor fluctuations under different osmotic conditions. In contrast, SEC6, a protein of the exocyst complex that is required for the water expulsion step, and a dynamin-like protein are upregulated under strong hypotonic conditions. The overexpression of a CreMIP1-GFP construct did not change the physiology of the CV. The functional implications of these results are discussed. PMID:25217463

  14. Improvements of Functional Validation by Analysis of Operational Problems

    NASA Astrophysics Data System (ADS)

    Di Nisio, Nicola; Reggestad, Vemund; Fuchs, Joachim

    2015-09-01

    As part of the TRP study “Improvements of Functional Validation by Analysis of Operational Problems”, we will explore the possibility of feeding the experience gained in the operational phase of a space mission into the design, development and verification phase of future missions. This paper will present the background of the problem and provide possible solutions that will be taken into account for the study. Also, a few examples of operational problems that could be used to improve the functional validation of future missions will be provided.

  15. Dynamic regulation of β1 subunit trafficking controls vascular contractility

    PubMed Central

    Leo, M. Dennis; Bannister, John P.; Narayanan, Damodaran; Nair, Anitha; Grubbs, Jordan E.; Gabrick, Kyle S.; Boop, Frederick A.; Jaggar, Jonathan H.

    2014-01-01

    Ion channels composed of pore-forming and auxiliary subunits control physiological functions in virtually all cell types. A conventional view is that channels assemble with their auxiliary subunits before anterograde plasma membrane trafficking of the protein complex. Whether the multisubunit composition of surface channels is fixed following protein synthesis or flexible and open to acute and, potentially, rapid modulation to control activity and cellular excitability is unclear. Arterial smooth muscle cells (myocytes) express large-conductance Ca2+-activated potassium (BK) channel α and auxiliary β1 subunits that are functionally significant modulators of arterial contractility. Here, we show that native BKα subunits are primarily (∼95%) plasma membrane-localized in human and rat arterial myocytes. In contrast, only a small fraction (∼10%) of total β1 subunits are located at the cell surface. Immunofluorescence resonance energy transfer microscopy demonstrated that intracellular β1 subunits are stored within Rab11A-postive recycling endosomes. Nitric oxide (NO), acting via cGMP-dependent protein kinase, and cAMP-dependent pathways stimulated rapid (≤1 min) anterograde trafficking of β1 subunit-containing recycling endosomes, which increased surface β1 almost threefold. These β1 subunits associated with surface-resident BKα proteins, elevating channel Ca2+ sensitivity and activity. Our data also show that rapid β1 subunit anterograde trafficking is the primary mechanism by which NO activates myocyte BK channels and induces vasodilation. In summary, we show that rapid β1 subunit surface trafficking controls functional BK channel activity in arterial myocytes and vascular contractility. Conceivably, regulated auxiliary subunit trafficking may control ion channel activity in a wide variety of cell types. PMID:24464482

  16. ILNCSIM: improved lncRNA functional similarity calculation model.

    PubMed

    Huang, Yu-An; Chen, Xing; You, Zhu-Hong; Huang, De-Shuang; Chan, Keith C C

    2016-05-01

    Increasing observations have indicated that lncRNAs play a significant role in various critical biological processes and the development and progression of various human diseases. Constructing lncRNA functional similarity networks could benefit the development of computational models for inferring lncRNA functions and identifying lncRNA-disease associations. However, little effort has been devoted to quantifying lncRNA functional similarity. In this study, we developed an Improved LNCRNA functional SIMilarity calculation model (ILNCSIM) based on the assumption that lncRNAs with similar biological functions tend to be involved in similar diseases. The main improvement comes from the combination of the concept of information content and the hierarchical structure of disease directed acyclic graphs for disease similarity calculation. ILNCSIM was combined with the previously proposed model of Laplacian Regularized Least Squares for lncRNA-Disease Association to further evaluate its performance. As a result, new model obtained reliable performance in the leave-one-out cross validation (AUCs of 0.9316 and 0.9074 based on MNDR and Lnc2cancer databases, respectively), and 5-fold cross validation (AUCs of 0.9221 and 0.9033 for MNDR and Lnc2cancer databases), which significantly improved the prediction performance of previous models. It is anticipated that ILNCSIM could serve as an effective lncRNA function prediction model for future biomedical researches. PMID:27028993

  17. Contractile reserve and calcium regulation are depressed in myocytes from chronically unloaded hearts

    NASA Technical Reports Server (NTRS)

    Ito, Kenta; Nakayama, Masaharu; Hasan, Faisal; Yan, Xinhua; Schneider, Michael D.; Lorell, Beverly H.

    2003-01-01

    BACKGROUND: Chronic cardiac unloading of the normal heart results in the reduction of left ventricular (LV) mass, but effects on myocyte contractile function are not known. METHODS AND RESULTS: Cardiac unloading and reduction in LV mass were induced by heterotopic heart transplantation to the abdominal aorta in isogenic rats. Contractility and [Ca(2+)](i) regulation in LV myocytes were studied at both 2 and 5 weeks after transplantation. Native in situ hearts from recipient animals were used as the controls for all experiments. Contractile function indices in myocytes from 2-week unloaded and native (control) hearts were similar under baseline conditions (0.5 Hz, 1.2 mmol/L [Ca(2+)](o), and 36 degrees C) and in response to stimulation with high [Ca(2+)](o) (range 2.5 to 4.0 mmol/L). In myocytes from 5-week unloaded hearts, there were no differences in fractional cell shortening and peak-systolic [Ca(2+)](i) at baseline; however, time to 50% relengthening and time to 50% decline in [Ca(2+)](i) were prolonged compared with controls. Severe defects in fractional cell shortening and peak-systolic [Ca(2+)](i) were elicited in myocytes from 5-week unloaded hearts in response to high [Ca(2+)](o). However, there were no differences in the contractile response to isoproterenol between myocytes from unloaded and native hearts. In 5-week unloaded hearts, but not in 2-week unloaded hearts, LV protein levels of phospholamban were increased (345% of native heart values). Protein levels of sarcoplasmic reticulum Ca(2+) ATPase and the Na(+)/Ca(2+) exchanger were not changed. CONCLUSIONS: Chronic unloading of the normal heart caused a time-dependent depression of myocyte contractile function, suggesting the potential for impaired performance in states associated with prolonged cardiac atrophy.

  18. How to make rapid eye movements "rapid": the role of growth factors for muscle contractile properties.

    PubMed

    Li, Tian; Feng, Cheng-Yuan; von Bartheld, Christopher S

    2011-03-01

    Different muscle functions require different muscle contraction properties. Saccade-generating extraocular muscles (EOMs) are the fastest muscles in the human body, significantly faster than limb skeletal muscles. Muscle contraction speed is subjected to plasticity, i.e., contraction speed can be adjusted to serve different demands, but little is known about the molecular mechanisms that control contraction speed. Therefore, we examined whether myogenic growth factors modulate contractile properties, including twitch contraction time (onset of force to peak force) and half relaxation time (peak force to half relaxation). We examined effects of three muscle-derived growth factors: insulin-like growth factor 1 (IGF1), cardiotrophin-1 (CT1), and glial cell line-derived neurotrophic factor (GDNF). In gain-of-function experiments, CT1 or GDNF injected into the orbit shortened contraction time, and IGF1 or CT1 shortened half relaxation time. In loss-of-function experiments with binding proteins or neutralizing antibodies, elimination of endogenous IGFs prolonged both contraction time and half relaxation time, while eliminating endogenous GDNF prolonged contraction time, with no effect on half relaxation time. Elimination of endogenous IGFs or CT1, but not GDNF, significantly reduced contractile force. Thus, IGF1, CT1, and GDNF have partially overlapping but not identical effects on muscle contractile properties. Expression of these three growth factors was measured in chicken and/or rat EOMs by real-time PCR. The "fast" EOMs express significantly more message encoding these growth factors and their receptors than skeletal muscles with slower contractile properties. Taken together, these findings indicate that EOM contractile kinetics is regulated by the amount of myogenic growth factors available to the muscle. PMID:21279379

  19. FAB (Functionally Alert Behavior Strategies) to Improve Self-Control

    ERIC Educational Resources Information Center

    Pagano, John

    2015-01-01

    This paper describes the FAB (Functionally Alert Behavior) Strategies approach to improve behavior in children and adolescents with complex behavioral challenges. FAB Strategies include evidence-based environmental adaptations, sensory modulation, positive behavioral support, and physical self-regulation strategies. FAB Strategies can be used by…

  20. Are Clinicians' Assessments of Improvements in Children's Functioning "Global"?

    ERIC Educational Resources Information Center

    De Los Reyes, Andres; Alfano, Candice A.; Beidel, Deborah C.

    2011-01-01

    In this study, the authors examined the relations among clinician ratings of treatment improvement and discrepancies between parent and blinded laboratory rater reports of child social functioning administered before and after treatment for social anxiety disorder. Participants included a clinic sample of 101 children (7-16 years old; M = 11.67,…

  1. Using Quality Function Deployment To Improve Academic Advising Processes.

    ERIC Educational Resources Information Center

    Barrows, Richard; Murray, Bruce

    1997-01-01

    Quality Function Deployment, a set of concepts and tools used in manufacturing engineering to link consumer needs with product design, can also improve academic advising systems and processes. The technique promotes structured, logical examination of students' advising needs and their relationship to advising system design, processes, methods,…

  2. Phosphotyrosine-dependent targeting of mitogen-activated protein kinase in differentiated contractile vascular cells.

    PubMed

    Khalil, R A; Menice, C B; Wang, C L; Morgan, K G

    1995-06-01

    Tyrosine phosphorylation has been linked to plasmalemmal targeting of src homology-2-containing proteins, activation of mitogen-activated protein (MAP) kinase, nuclear signaling, and proliferation of cultured cells. Significant tyrosine phosphorylation and MAP kinase activities have also been reported in differentiated cells, but the signaling role of tyrosine-phosphorylated MAP kinase in these cells is unclear. The spatial and temporal relation between phosphotyrosine and MAP kinase immunoreactivity was quantified in differentiated contractile vascular smooth muscle cells by using digital imaging microscopy. An initial association of MAP kinase with the plasmalemma required upstream protein kinase C activity but occurred in a tyrosine phosphorylation-independent manner. Subsequent to membrane association, a delayed redistribution of MAP kinase, colocalizing with the actin-binding protein caldesmon, occurred in a tyrosine phosphorylation-dependent manner. The apparent association of MAP kinase with the contractile proteins coincided with contractile activation. Thus, tyrosine phosphorylation appears to target MAP kinase to cytoskeletal proteins in contractile vascular cells. This targeting mechanism may determine the specific destination and thereby the specialized function of MAP kinase in other phenotypes. PMID:7538916

  3. Impaired pulmonary artery contractile responses in a rat model of microgravity: role of nitric oxide

    NASA Technical Reports Server (NTRS)

    Nyhan, Daniel; Kim, Soonyul; Dunbar, Stacey; Li, Dechun; Shoukas, Artin; Berkowitz, Dan E.

    2002-01-01

    Vascular contractile hyporesponsiveness is an important mechanism underlying orthostatic intolerance after microgravity. Baroreceptor reflexes can modulate both pulmonary resistance and capacitance function and thus cardiac output. We hypothesized, therefore, that pulmonary vasoreactivity is impaired in the hindlimb-unweighted (HLU) rat model of microgravity. Pulmonary artery (PA) contractile responses to phenylephrine (PE) and U-46619 (U4) were significantly decreased in the PAs from HLU vs. control (C) animals. N(G)-nitro-L-arginine methyl ester (10(-5) M) enhanced the contractile responses in the PA rings from both C and HLU animals and completely abolished the differential responses to PE and U4 in HLU vs. C animals. Vasorelaxant responses to ACh were significantly enhanced in PA rings from HLU rats compared with C. Moreover, vasorelaxant responses to sodium nitroprusside were also significantly enhanced. Endothelial nitric oxide synthase (eNOS) and soluble guanlyl cyclase expression were significantly enhanced in PA and lung tissue from HLU rats. In marked contrast, the expression of inducible nitric oxide synthase was unchanged in lung tissue. These data support the hypothesis that vascular contractile responsiveness is attenuated in PAs from HLU rats and that this hyporesponsiveness is due at least in part to increased nitric oxide synthase activity resulting from enhanced eNOS expression. These findings may have important implications for blood volume distribution and attenuated stroke volume responses to orthostatic stress after microgravity exposure.

  4. Vascular smooth muscle cell-derived adiponectin: a paracrine regulator of contractile phenotype.

    PubMed

    Ding, Min; Carrão, Ana Catarina; Wagner, Robert J; Xie, Yi; Jin, Yu; Rzucidlo, Eva M; Yu, Jun; Li, Wei; Tellides, George; Hwa, John; Aprahamian, Tamar R; Martin, Kathleen A

    2012-02-01

    Adiponectin is a cardioprotective adipokine derived predominantly from visceral fat. We recently demonstrated that exogenous adiponectin induces vascular smooth muscle cell (VSMC) differentiation via repression of mTORC1 and FoxO4. Here we report for the first time that VSMC express and secrete adiponectin, which acts in an autocrine and paracrine manner to regulate VSMC contractile phenotype. Adiponectin was found to be expressed in human coronary artery and mouse aortic VSMC. Importantly, siRNA knock-down of endogenous adiponectin in VSMC significantly reduced the expression of VSMC contractile proteins. Contractile protein deficiency was also observed in primary VSMC isolated from Adiponectin(-/-) mice. This deficiency could be rescued by culturing Adiponectin(-/-) VSMC in conditioned media from wild type (WT) VSMC. Moreover, the paracrine effect of VSMC-derived adiponectin was confirmed as adiponectin neutralizing antibody blocked the rescue. Overexpressed adiponectin also exerted paracrine effects on neighboring untransfected VSMC, which was also blocked by adiponectin neutralizing antibody. Interestingly, adiponectin expression was inducible by the PPARγ agonist rosiglitazone. Our data support an important role for VSMC-derived adiponectin in maintaining VSMC contractile phenotype, contributing to critical cardioprotective functions in the vascular wall. This article is part of a Special Issue entitled "Local Signaling in Myocytes". PMID:21952104

  5. Isotonic contractile impairment due to genetic CLC-1 chloride channel deficiency in myotonic mouse diaphragm muscle.

    PubMed

    van Lunteren, Erik; Pollarine, Jennifer; Moyer, Michelle

    2007-07-01

    The hallmark of genetic CLC-1 chloride channel deficiency in myotonic humans, goats and mice is delayed muscle relaxation resulting from persistent electrical discharges. In addition to the ion channel defect, muscles from myotonic humans and mice also have major changes in fibre type and myosin isoform composition, but the extent to which this affects isometric contractions remains controversial. Many muscles, including the diaphragm, shorten considerably during normal activities, but shortening contractions have never been assessed in myotonic muscle. The present study tested the hypothesis that CLC-1 deficiency leads to an impairment of muscle isotonic contractile performance. This was tested in vitro on diaphragm muscle from SWR/J-Clcn1(adr-mto)/J myotonic mice. The CLC-1-deficient muscle demonstrated delayed relaxation, as expected. During the contractile phase, there were significant reductions in power and work across a number of stimulation frequencies and loads in CLC-1-deficient compared with normal muscle, the magnitude of which in many instances exceeded 50%. Reductions in shortening and velocity of shortening occurred, and were more pronounced when calculated as a function of absolute than relative load. However, the maximal unloaded shortening velocity calculated from Hill's equation was not altered significantly. The impaired isotonic contractile performance of CLC-1-deficient muscle persisted during fatigue-inducing stimulation. These data indicate that genetic CLC-1 chloride channel deficiency in mice not only produces myotonia but also substantially worsens the isotonic contractile performance of diaphragm muscle. PMID:17483199

  6. Impaired cardiac contractility response to hemodynamic stress in S100A1-deficient mice.

    PubMed

    Du, Xiao-Jun; Cole, Timothy J; Tenis, Nora; Gao, Xiao-Ming; Köntgen, Frank; Kemp, Bruce E; Heierhorst, Jörg

    2002-04-01

    Ca(2+) signaling plays a central role in cardiac contractility and adaptation to increased hemodynamic demand. We have generated mice with a targeted deletion of the S100A1 gene coding for the major cardiac isoform of the large multigenic S100 family of EF hand Ca(2+)-binding proteins. S100A1(-/-) mice have normal cardiac function under baseline conditions but have significantly reduced contraction rate and relaxation rate responses to beta-adrenergic stimulation that are associated with a reduced Ca(2+) sensitivity. In S100A1(-/-) mice, basal left-ventricular contractility deteriorated following 3-week pressure overload by thoracic aorta constriction despite a normal adaptive hypertrophy. Surprisingly, heterozygotes also had an impaired response to acute beta-adrenergic stimulation but maintained normal contractility in response to chronic pressure overload that coincided with S100A1 upregulation to wild-type levels. In contrast to other genetic models with impaired cardiac contractility, loss of S100A1 did not lead to cardiac hypertrophy or dilation in aged mice. The data demonstrate that high S100A1 protein levels are essential for the cardiac reserve and adaptation to acute and chronic hemodynamic stress in vivo. PMID:11909974

  7. Impaired Cardiac Contractility Response to Hemodynamic Stress in S100A1-Deficient Mice

    PubMed Central

    Du, Xiao-Jun; Cole, Timothy J.; Tenis, Nora; Gao, Xiao-Ming; Köntgen, Frank; Kemp, Bruce E.; Heierhorst, Jörg

    2002-01-01

    Ca2+ signaling plays a central role in cardiac contractility and adaptation to increased hemodynamic demand. We have generated mice with a targeted deletion of the S100A1 gene coding for the major cardiac isoform of the large multigenic S100 family of EF hand Ca2+-binding proteins. S100A1−/− mice have normal cardiac function under baseline conditions but have significantly reduced contraction rate and relaxation rate responses to β-adrenergic stimulation that are associated with a reduced Ca2+ sensitivity. In S100A1−/− mice, basal left-ventricular contractility deteriorated following 3-week pressure overload by thoracic aorta constriction despite a normal adaptive hypertrophy. Surprisingly, heterozygotes also had an impaired response to acute β-adrenergic stimulation but maintained normal contractility in response to chronic pressure overload that coincided with S100A1 upregulation to wild-type levels. In contrast to other genetic models with impaired cardiac contractility, loss of S100A1 did not lead to cardiac hypertrophy or dilation in aged mice. The data demonstrate that high S100A1 protein levels are essential for the cardiac reserve and adaptation to acute and chronic hemodynamic stress in vivo. PMID:11909974

  8. A device for rapid and quantitative measurement of cardiac myocyte contractility

    NASA Astrophysics Data System (ADS)

    Gaitas, Angelo; Malhotra, Ricky; Li, Tao; Herron, Todd; Jalife, José

    2015-03-01

    Cardiac contractility is the hallmark of cardiac function and is a predictor of healthy or diseased cardiac muscle. Despite advancements over the last two decades, the techniques and tools available to cardiovascular scientists are limited in their utility to accurately and reliably measure the amplitude and frequency of cardiomyocyte contractions. Isometric force measurements in the past have entailed cumbersome attachment of isolated and permeabilized cardiomyocytes to a force transducer followed by measurements of sarcomere lengths under conditions of submaximal and maximal Ca2+ activation. These techniques have the inherent disadvantages of being labor intensive and costly. We have engineered a micro-machined cantilever sensor with an embedded deflection-sensing element that, in preliminary experiments, has demonstrated to reliably measure cardiac cell contractions in real-time. Here, we describe this new bioengineering tool with applicability in the cardiovascular research field to effectively and reliably measure cardiac cell contractility in a quantitative manner. We measured contractility in both primary neonatal rat heart cardiomyocyte monolayers that demonstrated a beat frequency of 3 Hz as well as human embryonic stem cell-derived cardiomyocytes with a contractile frequency of about 1 Hz. We also employed the β-adrenergic agonist isoproterenol (100 nmol l-1) and observed that our cantilever demonstrated high sensitivity in detecting subtle changes in both chronotropic and inotropic responses of monolayers. This report describes the utility of our micro-device in both basic cardiovascular research as well as in small molecule drug discovery to monitor cardiac cell contractions.

  9. Contractile properties of synthetic cationic polypeptides in guinea-pig isolated trachea.

    PubMed Central

    Spina, D.; Goldie, R. G.

    1994-01-01

    1. The synthetic polypeptides, poly-L-arginine, poly-L-lysine and poly-D-lysine contract guinea-pig isolated trachea in a concentration-dependent, epithelium-independent manner. Indomethacin augmented the contractile response to poly-L-arginine. 2. The contractile response to poly-L-arginine was not significantly inhibited by nicardipine, a selective L-type calcium channel blocker or by the histamine H1-receptor antagonist, mepyramine nor significantly augmented by the neutral endopeptidase inhibitor, phosphoramidon. 3. The contractile response to poly-L-arginine was inhibited in a concentration-dependent manner by prior incubation of guinea-pig tracheal rings with a number of anionic polypeptides including, low molecular weight heparin, poly-L-aspartic acid and bovine serum albumin. 4. In vitro capsaicin-induced desensitization failed to attenuate the contractile response to poly-L-arginine, suggesting little, if any role for sensory neuropeptides in the functional response in the guinea-pig. 5. Synthetic polypeptides induce an epithelium-independent, charge-dependent contraction of guinea-pig isolated trachea. PMID:8012709

  10. Analysis of Tyrosine Kinase Inhibitor-Mediated Decline in Contractile Force in Rat Engineered Heart Tissue

    PubMed Central

    Cuello, Friederike; Luther, Pradeep; Schulze, Thomas; Eder, Alexandra; Streichert, Thomas; Mannhardt, Ingra; Hirt, Marc N.; Schaaf, Sebastian; Stenzig, Justus; Force, Thomas

    2016-01-01

    Introduction Left ventricular dysfunction is a frequent and potentially severe side effect of many tyrosine kinase inhibitors (TKI). The mode of toxicity is not identified, but may include impairment of mitochondrial or sarcomeric function, autophagy or angiogenesis, either as an on-target or off-target mechanism. Methods and Results We studied concentration-response curves and time courses for nine TKIs in three-dimensional, force generating engineered heart tissue (EHT) from neonatal rat heart cells. We detected a concentration- and time-dependent decline in contractile force for gefitinib, lapatinib, sunitinib, imatinib, sorafenib, vandetanib and lestaurtinib and no decline in contractile force for erlotinib and dasatinib after 96 hours of incubation. The decline in contractile force was associated with an impairment of autophagy (LC3 Western blot) and appearance of autophagolysosomes (transmission electron microscopy). Conclusion This study demonstrates the feasibility to study TKI-mediated force effects in EHTs and identifies an association between a decline in contractility and inhibition of autophagic flux. PMID:26840448

  11. Cardiac-Specific Knockout of ETA Receptor Mitigates Paraquat-Induced Cardiac Contractile Dysfunction.

    PubMed

    Wang, Jiaxing; Lu, Songhe; Zheng, Qijun; Hu, Nan; Yu, Wenjun; Li, Na; Liu, Min; Gao, Beilei; Zhang, Guoyong; Zhang, Yingmei; Wang, Haichang

    2016-07-01

    Paraquat (1,1'-dim ethyl-4-4'-bipyridinium dichloride), a highly toxic quaternary ammonium herbicide widely used in agriculture, exerts potent toxic prooxidant effects resulting in multi-organ failure including the lung and heart although the underlying mechanism remains elusive. Recent evidence suggests possible involvement of endothelin system in paraquat-induced acute lung injury. This study was designed to examine the role of endothelin receptor A (ETA) in paraquat-induced cardiac contractile and mitochondrial injury. Wild-type (WT) and cardiac-specific ETA receptor knockout mice were challenged to paraquat (45 mg/kg, i.p.) for 48 h prior to the assessment of echocardiographic, cardiomyocyte contractile and intracellular Ca(2+) properties, as well as apoptosis and mitochondrial damage. Levels of the mitochondrial proteins for biogenesis and oxidative phosphorylation including UCP2, HSP90 and PGC1α were evaluated. Our results revealed that paraquat elicited cardiac enlargement, mechanical anomalies including compromised echocardiographic parameters (elevated left ventricular end-systolic and end-diastolic diameters as well as reduced factional shortening), suppressed cardiomyocyte contractile function, intracellular Ca(2+) handling, overt apoptosis and mitochondrial damage. ETA receptor knockout itself failed to affect myocardial function, apoptosis, mitochondrial integrity and mitochondrial protein expression. However, ETA receptor knockout ablated or significantly attenuated paraquat-induced cardiac contractile and intracellular Ca(2+) defect, apoptosis and mitochondrial damage. Taken together, these findings revealed that endothelin system in particular the ETA receptor may be involved in paraquat-induced toxic myocardial contractile anomalies possibly related to apoptosis and mitochondrial damage. PMID:26089164

  12. Peptide-based inhibition of NF-κB rescues diaphragm muscle contractile dysfunction in a murine model of Duchenne muscular dystrophy.

    PubMed

    Peterson, Jennifer M; Kline, William; Canan, Benjamin D; Ricca, Daniel J; Kaspar, Brian; Delfín, Dawn A; DiRienzo, Kelly; Clemens, Paula R; Robbins, Paul D; Baldwin, Albert S; Flood, Pat; Kaumaya, Pravin; Freitas, Michael; Kornegay, Joe N; Mendell, Jerry R; Rafael-Fortney, Jill A; Guttridge, Denis C; Janssen, Paul M L

    2011-01-01

    Deterioration of diaphragm function is one of the prominent factors that contributes to the susceptibility of serious respiratory infections and development of respiratory failure in patients with Duchenne Muscular Dystrophy (DMD). The NF-κB signaling pathway has been implicated as a contributing factor of dystrophic pathology, making it a potential therapeutic target. Previously, we demonstrated that pharmacological inhibition of NF-κB via a small NEMO Binding Domain (NBD) peptide was beneficial for reducing pathological features of mdx mice. Now, we stringently test the effectiveness and clinical potential of NBD by treating mdx mice with various formulations of NBD and use diaphragm function as our primary outcome criteria. We found that administering DMSO-soluble NBD rescued 78% of the contractile deficit between mdx and wild-type (WT) diaphragm. Interestingly, synthesis of a GLP NBD peptide as an acetate salt permitted its solubility in water, but as a negative consequence, also greatly attenuated functional efficacy. However, replacing the acetic acid counterion of the NBD peptide with trifluoroacetic acid retained the peptide's water solubility and significantly restored mdx diaphragm contractile function and improved histopathological indices of disease in both diaphragm and limb muscle. Together, these results support the feasibility of using a mass-produced, water-soluble NBD peptide for clinical use. PMID:21267511

  13. A quantitative analysis of contractility in active cytoskeletal protein networks.

    PubMed

    Bendix, Poul M; Koenderink, Gijsje H; Cuvelier, Damien; Dogic, Zvonimir; Koeleman, Bernard N; Brieher, William M; Field, Christine M; Mahadevan, L; Weitz, David A

    2008-04-15

    Cells actively produce contractile forces for a variety of processes including cytokinesis and motility. Contractility is known to rely on myosin II motors which convert chemical energy from ATP hydrolysis into forces on actin filaments. However, the basic physical principles of cell contractility remain poorly understood. We reconstitute contractility in a simplified model system of purified F-actin, muscle myosin II motors, and alpha-actinin cross-linkers. We show that contractility occurs above a threshold motor concentration and within a window of cross-linker concentrations. We also quantify the pore size of the bundled networks and find contractility to occur at a critical distance between the bundles. We propose a simple mechanism of contraction based on myosin filaments pulling neighboring bundles together into an aggregated structure. Observations of this reconstituted system in both bulk and low-dimensional geometries show that the contracting gels pull on and deform their surface with a contractile force of approximately 1 microN, or approximately 100 pN per F-actin bundle. Cytoplasmic extracts contracting in identical environments show a similar behavior and dependence on myosin as the reconstituted system. Our results suggest that cellular contractility can be sensitively regulated by tuning the (local) activity of molecular motors and the cross-linker density and binding affinity. PMID:18192374

  14. Aerobic Exercise Improves Cognition and Motor Function Poststroke

    PubMed Central

    Quaney, Barbara M.; Boyd, Lara A.; McDowd, Joan M.; Zahner, Laura H.; He, Jianghua; Mayo, Matthew S.; Macko, Richard F.

    2010-01-01

    Background Cognitive deficits impede stroke recovery. Aerobic exercise (AEX) improves cognitive executive function (EF) processes in healthy individuals, although the learning benefits after stroke are unknown. Objective To understand AEX-induced improvements in EF, motor learning, and mobility poststroke. Methods Following cardiorespiratory testing, 38 chronic stroke survivors were randomized to 2 different groups that exercised 3 times a week (45-minute sessions) for 8 weeks. The AEX group (n = 19; 9 women; 10 men; 64.10 ± 12.30 years) performed progressive resistive stationary bicycle training at 70% maximal heart rate, whereas the Stretching Exercise (SE) group (n = 19; 12 women; 7 men; 58.96 ± 14.68 years) performed stretches at home. Between-group comparisons were performed on the change in performance at “Post” and “Retention” (8 weeks later) for neuropsychological and motor function measures. Results Vo2max significantly improved at Post with AEX (P = .04). AEX also improved motor learning in the less-affected hand, with large effect sizes (Cohen’s d calculation). Specifically, AEX significantly improved information processing speed on the serial reaction time task (SRTT; ie, “procedural motor learning”) compared with the SE group at Post (P = .024), but not at Retention. Also, at Post (P = .038), AEX significantly improved predictive force accuracy for a precision grip task requiring attention and conditional motor learning of visual cues. Ambulation and sit-to-stand transfers were significantly faster in the AEX group at Post (P = .038), with balance control significantly improved at Retention (P = .041). EF measurements were not significantly different for the AEX group. Conclusion AEX improved mobility and selected cognitive domains related to motor learning, which enhances sensorimotor control after stroke. PMID:19541916

  15. Using Operational Analysis to Improve Access to Pulmonary Function Testing.

    PubMed

    Ip, Ada; Asamoah-Barnieh, Raymond; Bischak, Diane P; Davidson, Warren J; Flemons, W Ward; Pendharkar, Sachin R

    2016-01-01

    Background. Timely pulmonary function testing is crucial to improving diagnosis and treatment of pulmonary diseases. Perceptions of poor access at an academic pulmonary function laboratory prompted analysis of system demand and capacity to identify factors contributing to poor access. Methods. Surveys and interviews identified stakeholder perspectives on operational processes and access challenges. Retrospective data on testing demand and resource capacity was analyzed to understand utilization of testing resources. Results. Qualitative analysis demonstrated that stakeholder groups had discrepant views on access and capacity in the laboratory. Mean daily resource utilization was 0.64 (SD 0.15), with monthly average utilization consistently less than 0.75. Reserved testing slots for subspecialty clinics were poorly utilized, leaving many testing slots unfilled. When subspecialty demand exceeded number of reserved slots, there was sufficient capacity in the pulmonary function schedule to accommodate added demand. Findings were shared with stakeholders and influenced scheduling process improvements. Conclusion. This study highlights the importance of operational data to identify causes of poor access, guide system decision-making, and determine effects of improvement initiatives in a variety of healthcare settings. Importantly, simple operational analysis can help to improve efficiency of health systems with little or no added financial investment. PMID:27445545

  16. Using Operational Analysis to Improve Access to Pulmonary Function Testing

    PubMed Central

    Ip, Ada; Asamoah-Barnieh, Raymond; Bischak, Diane P.; Davidson, Warren J.; Flemons, W. Ward; Pendharkar, Sachin R.

    2016-01-01

    Background. Timely pulmonary function testing is crucial to improving diagnosis and treatment of pulmonary diseases. Perceptions of poor access at an academic pulmonary function laboratory prompted analysis of system demand and capacity to identify factors contributing to poor access. Methods. Surveys and interviews identified stakeholder perspectives on operational processes and access challenges. Retrospective data on testing demand and resource capacity was analyzed to understand utilization of testing resources. Results. Qualitative analysis demonstrated that stakeholder groups had discrepant views on access and capacity in the laboratory. Mean daily resource utilization was 0.64 (SD 0.15), with monthly average utilization consistently less than 0.75. Reserved testing slots for subspecialty clinics were poorly utilized, leaving many testing slots unfilled. When subspecialty demand exceeded number of reserved slots, there was sufficient capacity in the pulmonary function schedule to accommodate added demand. Findings were shared with stakeholders and influenced scheduling process improvements. Conclusion. This study highlights the importance of operational data to identify causes of poor access, guide system decision-making, and determine effects of improvement initiatives in a variety of healthcare settings. Importantly, simple operational analysis can help to improve efficiency of health systems with little or no added financial investment. PMID:27445545

  17. Improved Functional Characteristics of Whey Protein Hydrolysates in Food Industry

    PubMed Central

    Jeewanthi, Renda Kankanamge Chaturika; Lee, Na-Kyoung; Paik, Hyun-Dong

    2015-01-01

    This review focuses on the enhanced functional characteristics of enzymatic hydrolysates of whey proteins (WPHs) in food applications compared to intact whey proteins (WPs). WPs are applied in foods as whey protein concentrates (WPCs), whey protein isolates (WPIs), and WPHs. WPs are byproducts of cheese production, used in a wide range of food applications due to their nutritional validity, functional activities, and cost effectiveness. Enzymatic hydrolysis yields improved functional and nutritional benefits in contrast to heat denaturation or native applications. WPHs improve solubility over a wide range of pH, create viscosity through water binding, and promote cohesion, adhesion, and elasticity. WPHs form stronger but more flexible edible films than WPC or WPI. WPHs enhance emulsification, bind fat, and facilitate whipping, compared to intact WPs. Extensive hydrolyzed WPHs with proper heat applications are the best emulsifiers and addition of polysaccharides improves the emulsification ability of WPHs. Also, WPHs improve the sensorial properties like color, flavor, and texture but impart a bitter taste in case where extensive hydrolysis (degree of hydrolysis greater than 8%). It is important to consider the type of enzyme, hydrolysis conditions, and WPHs production method based on the nature of food application. PMID:26761849

  18. Inosine improves functional recovery after experimental traumatic brain injury.

    PubMed

    Dachir, Shlomit; Shabashov, Dalia; Trembovler, Victoria; Alexandrovich, Alexander G; Benowitz, Larry I; Shohami, Esther

    2014-03-25

    Despite years of research, no effective therapy is yet available for the treatment of traumatic brain injury (TBI). The most prevalent and debilitating features in survivors of TBI are cognitive deficits and motor dysfunction. A potential therapeutic method for improving the function of patients following TBI would be to restore, at least in part, plasticity to the CNS in a controlled way that would allow for the formation of compensatory circuits. Inosine, a naturally occurring purine nucleoside, has been shown to promote axon collateral growth in the corticospinal tract (CST) following stroke and focal TBI. In the present study, we investigated the effects of inosine on motor and cognitive deficits, CST sprouting, and expression of synaptic proteins in an experimental model of closed head injury (CHI). Treatment with inosine (100 mg/kg i.p. at 1, 24 and 48 h following CHI) improved outcome after TBI, significantly decreasing the neurological severity score (NSS, p<0.04 vs. saline), an aggregate measure of performance on several tasks. It improved non-spatial cognitive performance (object recognition, p<0.016 vs. saline) but had little effect on sensorimotor coordination (rotarod) and spatial cognitive functions (Y-maze). Inosine did not affect CST sprouting in the lumbar spinal cord but did restore levels of the growth-associated protein GAP-43 in the hippocampus, though not in the cerebral cortex. Our results suggest that inosine may improve functional outcome after TBI. PMID:24502983

  19. Improved Functional Characteristics of Whey Protein Hydrolysates in Food Industry.

    PubMed

    Jeewanthi, Renda Kankanamge Chaturika; Lee, Na-Kyoung; Paik, Hyun-Dong

    2015-01-01

    This review focuses on the enhanced functional characteristics of enzymatic hydrolysates of whey proteins (WPHs) in food applications compared to intact whey proteins (WPs). WPs are applied in foods as whey protein concentrates (WPCs), whey protein isolates (WPIs), and WPHs. WPs are byproducts of cheese production, used in a wide range of food applications due to their nutritional validity, functional activities, and cost effectiveness. Enzymatic hydrolysis yields improved functional and nutritional benefits in contrast to heat denaturation or native applications. WPHs improve solubility over a wide range of pH, create viscosity through water binding, and promote cohesion, adhesion, and elasticity. WPHs form stronger but more flexible edible films than WPC or WPI. WPHs enhance emulsification, bind fat, and facilitate whipping, compared to intact WPs. Extensive hydrolyzed WPHs with proper heat applications are the best emulsifiers and addition of polysaccharides improves the emulsification ability of WPHs. Also, WPHs improve the sensorial properties like color, flavor, and texture but impart a bitter taste in case where extensive hydrolysis (degree of hydrolysis greater than 8%). It is important to consider the type of enzyme, hydrolysis conditions, and WPHs production method based on the nature of food application. PMID:26761849

  20. Cryoprecipitate infusion fails to improve organ function in septic shock.

    PubMed

    Hesselvik, F; Brodin, B; Carlsson, C; Cedergren, B; Jorfeldt, L; Liedén, G

    1987-05-01

    Plasma fibronectin may be of critical importance for the septic patient through its proposed function as the major opsonin for macrophage clearance of circulating, noncellular debris. As a rule, critically ill, septic patients are depleted of fibronectin. In earlier uncontrolled studies, infusion of fibronectin-rich cryoprecipitate had resulted in improved renal and pulmonary functions and changes in peripheral hemodynamics. In this controlled study, 32 septic ICU patients (mean initial fibronectin level = 60% of normal) received cryoprecipitate or control infusions. Although the fibronectin level was significantly elevated to the normal range in the cryoprecipitate group, no effects were seen in hemodynamics, oxygen metabolism, or lung and kidney functions. Our results indicate that this form of fibronectin therapy does not influence the impaired organ function in septic shock. PMID:3552444

  1. Effects of Acetaminophen on Left Atrial Contractility

    PubMed Central

    Chang, Jun-Hei; Cheng, Pao-Yun; Hsu, Chih-Hsueng; Chen, Yao-Chang; Hong, Po-Da

    2016-01-01

    Background It has been observed that acetaminophen shows cardioprotective efficacy in mammals. In this study, we investigated the electromechanical effects of acetaminophen on the left atrium (LA). Methods Conventional microelectrodes were used to record the action potentials (AP) in rabbit LA preparations. The action potential duration (APD) at repolarization levels of 90%, 50% and 20% of the AP amplitude (APD90, APD50, and APD20, respectively), resting membrane potential, and contractile force were measured during 2 Hz electrical stimulation before and after sequential acetaminophen administration to the LA. Results Acetaminophen (0.1, 0.3, 1, and 3 mM) reduced APD20 from 9.4 ± 1.2 to 8.0 ± 1.1 (p < 0.05), 7.1 ± 0.8 (p < 0.05), 7.8 ± 1.1, and 6.8 ± 1.2 ms (p < 0.05), respectively, and APD50 from 20.2 ± 1.9 to 17.4 ± 2.0, 15.6 ± 1.8 (p < 0.05), 15.8 ± 2.2 (p < 0.05), and 14.1 ± 2.4 ms (p < 0.05), respectively, in a concentration-dependent manner. APD90 was reduced from 72.0 ± 3.6 to 64.7 ± 4.2, 61.9 ± 4.3, 60.5 ± 3.7, and 53.4 ± 4.4 ms (p < 0.05), respectively. Acetaminophen increased LA contractility from 45 ± 9 to 52 ± 10 (p < 0.05), 55 ± 9 (p < 0.01), 58 ± 9 (p < 0.01), and 60 ± 9 mg (p < 0.01), respectively, in a concentration-dependent manner. In the presence of the NOS inhibitor L-NAME or PKG-I inhibitor DT-2, additional acetaminophen treatment did not significantly increase LA contractility. Conclusions Acetaminophen modulated the electromechanical characteristics of LA by inhibiting the NOS and PKG I pathway, and then contributed to the positive inotropic effect. PMID:27471362

  2. The Structural Basis of Functional Improvement in Response to Human Umbilical Cord Blood Stem Cell Transplantation in Hearts with Post-Infarct LV Remodeling

    PubMed Central

    Chen, Yong; Ye, Lei; Zhong, Jia; Li, Xin; Yan, Chen; Chandler, Margaret P.; Calvin, Steve; Xiao, Feng; Negia, Mesfin; Low, Walter C.; Zhang, Jianyi; Yu, Xin

    2015-01-01

    Cellular therapy for myocardial repair has been one of the most intensely investigated interventional strategies for acute myocardium infarction. Although the therapeutic potential of stem cells has been demonstrated in various studies, the underlying mechanisms for such improvement are poorly understood. In the present study, we investigated the long-term effects of stem cell therapy on both myocardial fiber organization and regional contractile function using a rat model of post-infarct remodeling. Human non-hematopoietic umbilical cord blood stem cells (nh-UCBSCs) were administered via tail vein to rats 2 days after infarct surgery. Animals were maintained without immunosuppressive therapy. In vivo and ex vivo MR imaging was performed on infarct hearts ten months after cell transplantation. Compared to the age-matched rats exposed to the identical surgery, both global and regional cardiac function of the nh-UCBSC-treated hearts, such as ejection fraction, ventricular strain and torsion, were significantly improved. More importantly, the treated hearts exhibited preserved fiber orientation and water diffusivities that were similar to those in sham-operated control hearts. These data provide the first evidence that nh-UCBSC treatment may prevent/delay untoward structural remodeling in post-infarct hearts, which supports the improved LV function observed in vivo in the absence of immunosuppression, suggesting a beneficial paracrine effect that occurred with the cellular therapy. PMID:24332083

  3. Inhibition of tissue transglutaminase 2 attenuates contractility of pregnant human myometrium.

    PubMed

    Alcock, Joelle; Warren, Averil Y; Goodson, Yvonne J; Hill, Stephen J; Khan, Raheela N; Lymn, Joanne S

    2011-04-01

    Premature delivery remains a serious risk factor in pregnancy, with currently licensed tocolytics unable to offer significant improvement in neonatal outcome. Further understanding of the regulators of uterine contractility is required to enable the development of novel and more effective tocolytic therapies. The transglutaminase family is a class of calcium-dependent, transamidating enzymes, of which tissue transglutaminase 2 is a multifunctional enzyme with roles in cell survival, migration, adhesion, and contractility. The aim of the present study was to investigate the role of this enzyme in regulating the contractility of pregnant human myometrium. Tissue strips from biopsy samples obtained at elective cesarean section were either allowed to contract spontaneously or induced to contract with oxytocin, phenylephrine, or bradykinin. Activity integrals, used to measure contractile activity, were taken following cumulative additions of the reversible, polyamine transglutaminase inhibitors cystamine and mono-dansylcadaverine and the irreversible, site-specific transglutaminase inhibitors N-benzyloxycarbonyl-l-phenylalanyl-6-dimethylsulfonium-5-oxo-L-norleucine and 1,3-dimethyl-2[(oxopropyl)thio]imidazolium. The ability of cystamine and mono-dansylcadaverine to affect oxytocin-mediated calcium mobilization within primary cultured myometrial cells was also measured utilizing a calcium indicator. All inhibitors attenuated myometrial contractions in a concentration-dependent manner independent of the method of contraction stimulus. Similarly cultured myometrial cells preincubated with cystamine and mono-dansylcadaverine displayed an altered calcium response to oxytocin stimulation. Our findings demonstrate a potential role for tissue transglutaminase 2 in regulating uterine contractility in pregnant human myometrium that may be associated with the calcium signaling cascade required for contraction. PMID:21123816

  4. Considerations to improve functional annotations in biological databases.

    PubMed

    Benítez-Páez, Alfonso

    2009-12-01

    Despite the great effort to design efficient systems allowing the electronic indexation of information concerning genes, proteins, structures, and interactions published daily in scientific journals, some problems are still observed in specific tasks such as functional annotation. The annotation of function is a critical issue for bioinformatic routines, such as for instance, in functional genomics and the further prediction of unknown protein function, which are highly dependent of the quality of existing annotations. Some information management systems evolve to efficiently incorporate information from large-scale projects, but often, annotation of single records from the literature is difficult and slow. In this short report, functional characterizations of a representative sample of the entire set of uncharacterized proteins from Escherichia coli K12 was compiled from Swiss-Prot, PubMed, and EcoCyc and demonstrate a functional annotation deficit in biological databases. Some issues are postulated as causes of the lack of annotation, and different solutions are evaluated and proposed to avoid them. The hope is that as a consequence of these observations, there will be new impetus to improve the speed and quality of functional annotation and ultimately provide updated, reliable information to the scientific community. PMID:20050264

  5. C-Type Natriuretic Peptide Improves Left Ventricular Functional Performance at Rest and Restores Normal Exercise Responses after Heart Failure.

    PubMed

    Li, Tiankai; Cheng, Heng-Jie; Ohte, Nobuyuki; Hasegawa, Hiroshi; Morimoto, Atsushi; Herrington, David M; Little, William C; Li, Weimin; Cheng, Che Ping

    2016-06-01

    In heart failure (HF), the impaired left ventricular (LV) arterial coupling and diastolic dysfunction present at rest are exacerbated during exercise. C-type natriuretic peptide (CNP) is elevated in HF; however, its functional effects are unclear. We tested the hypotheses that CNP with vasodilating, natriuretic, and positive inotropic and lusitropic actions may prevent this abnormal exercise response after HF. We determined the effects of CNP (2 μg/kg plus 0.4 μg/kg per minute, i.v., 20 minutes) on plasma levels of cGMP before and after HF and assessed LV dynamics during exercise in 10 chronically instrumented dogs with pacing-induced HF. Compared with the levels before HF, CNP infusion caused significantly greater increases in cGMP levels after HF. After HF, at rest, CNP administration significantly reduced LV end-systolic pressure (PES), arterial elastance (EA), and end-diastolic pressure. The peak mitral flow (dV/dtmax) was also increased owing to decreased minimum LVP (LVPmin) and the time constant of LV relaxation (τ) (P < 0.05). In addition, LV contractility (EES) was increased. The LV-arterial coupling (EES/EA) was improved. The beneficial effects persisted during exercise. Compared with exercise in HF preparation, treatment with CNP caused significantly less important increases in PES but significantly decreased τ (34.2 vs. 42.6 ms) and minimum left ventricular pressure with further augmented dV/dtmax Both EES, EES/EA (0.87 vs. 0.32) were increased. LV mechanical efficiency improved from 0.38 to 0.57 (P < 0.05). After HF, exogenous CNP produces arterial vasodilatation and augments LV contraction, relaxation, diastolic filling, and LV arterial coupling, thus improving LV performance at rest and restoring normal exercise responses after HF. PMID:27026682

  6. Predicting changes in cardiac myocyte contractility during early drug discovery with in vitro assays

    SciTech Connect

    Morton, M.J.; Armstrong, D.; Abi Gerges, N.; Bridgland-Taylor, M.; Pollard, C.E.; Bowes, J.; Valentin, J.-P.

    2014-09-01

    Cardiovascular-related adverse drug effects are a major concern for the pharmaceutical industry. Activity of an investigational drug at the L-type calcium channel could manifest in a number of ways, including changes in cardiac contractility. The aim of this study was to define which of the two assay technologies – radioligand-binding or automated electrophysiology – was most predictive of contractility effects in an in vitro myocyte contractility assay. The activity of reference and proprietary compounds at the L-type calcium channel was measured by radioligand-binding assays, conventional patch-clamp, automated electrophysiology, and by measurement of contractility in canine isolated cardiac myocytes. Activity in the radioligand-binding assay at the L-type Ca channel phenylalkylamine binding site was most predictive of an inotropic effect in the canine cardiac myocyte assay. The sensitivity was 73%, specificity 83% and predictivity 78%. The radioligand-binding assay may be run at a single test concentration and potency estimated. The least predictive assay was automated electrophysiology which showed a significant bias when compared with other assay formats. Given the importance of the L-type calcium channel, not just in cardiac function, but also in other organ systems, a screening strategy emerges whereby single concentration ligand-binding can be performed early in the discovery process with sufficient predictivity, throughput and turnaround time to influence chemical design and address a significant safety-related liability, at relatively low cost. - Highlights: • The L-type calcium channel is a significant safety liability during drug discovery. • Radioligand-binding to the L-type calcium channel can be measured in vitro. • The assay can be run at a single test concentration as part of a screening cascade. • This measurement is highly predictive of changes in cardiac myocyte contractility.

  7. Neuropilin 1 Is Essential for Gastrointestinal Smooth Muscle Contractility and Motility in Aged Mice

    PubMed Central

    Yamaji, Maiko; Mahmoud, Marwa; Evans, Ian M.; Zachary, Ian C.

    2015-01-01

    Background and Aims Neuropilin 1 (NRP1) is a non-tyrosine kinase receptor for vascular endothelial growth factor (VEGF) and class 3 semaphorins, playing a role in angiogenesis and neuronal axon guidance, respectively. NRP1 is expressed in smooth muscle cells (SMC) but the functional role of NRP1 in SMC has not been elucidated. We therefore investigated the biological relevance of NRP1 in SMC in vivo by generating mice with SMC-specific Nrp1 deficiency. Methods Conditional gene targeting generated SMC-specific Nrp1 knockout mice (Nrp1SMKO) in which Cre recombinase is driven by the smooth muscle-specific myosin heavy chain (smMHC) promoter. Results SMC-specific Nrp1 deficiency resulted in a significant reduction in intestinal length by 6 months, and, by 18 months, in severe constipation, and enlargement of the intestine consistent with chronic intestinal pseudo-obstruction. These effects were associated with significant thinning of the intestinal smooth muscle, and decreased intestinal contractility. Expression of contractile proteins was reduced in Nrp1SMKO mice, including the smMHC isoform, SMB, whereas we observed a significant increase in the expression of the small-conductance calcium-activated potassium channel 3 (SK3/KCa2.3), implicated in negative regulation of smooth muscle contraction. Conclusions Nrp1 deficiency in visceral SMC results in adult-onset defects in gastrointestinal contractility and motility and causes a shift to a less contractile SMC phenotype. These findings indicate a new role for Nrp1 in the maintenance of the visceral SMC contractile phenotype required for normal GI motility in aged mice. PMID:25659123

  8. Reconstructive Osteotomy for Ankle Malunion Improves Patient Satisfaction and Function

    PubMed Central

    Tohyama, Masahiko; Yasuda, Hiroyuki; Konishi, Sadahiko; Waseda, Akeo

    2015-01-01

    Treatment of chronic symptoms caused by a malunion is a difficult problem in orthopedic surgery. We encountered a case of ankle malunion at our hospital about 1 year after the first operation. The patient had been unable to walk with weight-bearing but regained the ability to walk after reconstructive osteotomy of the fibula. Functional scores for the foot and ankle were significantly improved after intervention. Reconstructive osteotomy appears to represent a good option for ankle malunion. PMID:26064743

  9. Improved regional ventricular function after successful surgical revascularization

    SciTech Connect

    Brundage, B.H.; Massie, B.M.; Botvinick, E.H.

    1984-04-01

    Left ventricular segments with reversible asynergy at rest demonstrate reversible myocardial perfusion defects on exercise thallium-201 scintigrams. To determine if improved perfusion eliminates asynergy at rest, 23 patients with angina (stable in 21, unstable in 2) were studied before and after coronary artery bypass surgery. All patients underwent exercise myocardial perfusion scintigraphy, contrast ventriculography and coronary arteriography before and after surgery. Selective graft angiography was performed during the postoperative catheterization to determine graft patency. Segmental ventricular function was quantitated by a regional fraction method. The scintigrams were divided into five regions and compared with the corresponding regions of the ventriculogram. Seventy-one of a possible 142 ventricular segments exhibited exercise-induced perfusion deficits. Preoperative regional ejection fraction was normal in 42 of these segments and abnormal in 29. Postoperatively, in 19 of the abnormal segments, function improved or normalized. All these segments had improved perfusion during exercise after surgery and were supplied by a patent bypass graft. Nine of the 10 segments in which abnormal wall motion persisted postoperatively continued to have exercise-induced perfusion deficits, and 9 of the 10 segments were supplied by an occluded or stenotic graft or one with poor run off. Of the 42 segments with normal wall motion preoperatively, 30 had improved perfusion after surgery and 35 maintained normal function. This study indicates that asynergy at rest is permanently reversed after coronary bypass surgery if improved myocardial perfusion can be documented. These findings are consistent with but do not prove the concept that reversible rest asynergy may reflect chronic ischemia or a prolonged effect from previous ischemic episodes.

  10. Spiral waves on a contractile tissue

    NASA Astrophysics Data System (ADS)

    Mesin, L.; Ambrosi, D.

    2011-02-01

    In a healthy cardiac tissue, electric waves propagate in the form of a travelling pulse, from the apex to the base, and activate the contraction of the heart. Defects in the propagation can destabilize travelling fronts and originate possible new periodic solutions, as spiral waves. Spiral waves are quite stable, but the interplay between currents and strain can distort the periodic pattern, provided the coupling is strong enough. In this paper we investigate the stability of spiral waves on a contractile medium in a non-standard framework, in which the electrical potential dictates the active strain (not stress) of the muscle. The role of conducting and contracting fibers is included in the model and periodic boundary conditions are adopted. A correlation analysis allows to evaluate numerically the range of stability of the parameters for the spiral waves, depending on the strain of the contracted fibers and on the magnitude of the stretch activated current.

  11. Targeted therapies to improve CFTR function in cystic fibrosis.

    PubMed

    Brodlie, Malcolm; Haq, Iram J; Roberts, Katie; Elborn, J Stuart

    2015-01-01

    Cystic fibrosis is the most common genetically determined, life-limiting disorder in populations of European ancestry. The genetic basis of cystic fibrosis is well established to be mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene that codes for an apical membrane chloride channel principally expressed by epithelial cells. Conventional approaches to cystic fibrosis care involve a heavy daily burden of supportive treatments to combat lung infection, help clear airway secretions and maintain nutritional status. In 2012, a new era of precision medicine in cystic fibrosis therapeutics began with the licensing of a small molecule, ivacaftor, which successfully targets the underlying defect and improves CFTR function in a subgroup of patients in a genotype-specific manner. Here, we review the three main targeted approaches that have been adopted to improve CFTR function: potentiators, which recover the function of CFTR at the apical surface of epithelial cells that is disrupted in class III and IV genetic mutations; correctors, which improve intracellular processing of CFTR, increasing surface expression, in class II mutations; and production correctors or read-through agents, which promote transcription of CFTR in class I mutations. The further development of such approaches offers great promise for future therapeutic strategies in cystic fibrosis. PMID:26403534

  12. Modification of biochar for functionality improvement in soils

    NASA Astrophysics Data System (ADS)

    Zwart, Kor; Kuikman, Peter; Ross, Anrew; Takaya, Chibi; Singh, Surjit; Kocaturk, Pelin; Visser, Rian

    2014-05-01

    Application of biochar to soils is generally considered and practiced in order to improve specific soil functions such as CEC, moisture and nutrient retention and providing additional habitat for micro-organisms. Improvement of these soil functions should lead to a higher crop yield. This would be added value to the long term sequestration of carbon in soils and contribution to renewable energy from producing and using biochar. The concept of using biochar for soil amendment is predicated on biochar behaving in a similar manner as soil organic matter (SOM) does. However, if one critically compares the properties of biochar with the properties of SOM, it is evident that biochar is rather different from SOM [Zwart, 2013 ;Zwart & Kuikman, 2013]. We have has produced a range of biochar from different feedstock using pyrolysis, gasification and hydrothermal carbonisation resulting in chars with significantly different properties. The project also investigates and tested several possibilities for improving the functionality of biochar in soils by either(i) selection of feedstock, (ii), selection of processing conditions and (iii) chemical and physical modification of biochar during and after the production process. Post modification includes the chemical treatment of biochars with either H2O2, KOH, H2SO4 and transitional metals such as Fe and investigates their effect on surface functionality, porosity, surface area, CEC and phosphate sorption. The influence of the addition of chemical modifiers and oxidants during pyrolysis and gasification has also been investigated and their effect on surface functionality determined using similar techniques. The influence of the original biomass structure on the morphology of the resultant biochars has been investigated using scanning electron microscopy.

  13. Mechanisms of uterine contractility in laying hens.

    PubMed

    Kupittayanant, S; Kupittayanant, P; Suwannachat, C

    2009-10-01

    The physiological basis of uterine contractility in laying hens is not well understood, but a better understanding is important for understanding the mechanisms governing egg laying. The characteristics of uterine contractility arising spontaneously or by prostaglandin F(2alpha) (PGF(2alpha)) stimulation were therefore examined and the underlying mechanisms investigated. Uterine strips were isolated from laying hens 4h before oviposition and force measured. These strips remained healthy in vitro and produced regular spontaneous contractions. The contractions were phasic and could be recorded for several hours. Exposure to nifedipine, the specific L-type Ca channel blocker, led to the abolition of force. The contraction amplitude and frequency were significantly increased when Bay K8644, an agonist of L-type Ca channels, was applied or when the concentration of extracellular Ca was elevated. Spontaneous contractions were also significantly inhibited by wortmannin, the specific inhibitor of myosin light chain kinase (MLCK). When 1 microM PGF(2alpha) was applied to spontaneously contracting uterus, it significantly increased their amplitude and frequency of the contractions. As with spontaneous contractions, PGF(2alpha)-induced force production was abolished by nifedipine and wortmannin. In the absence of extracellular Ca, a small but tonic force was generated upon application of PGF(2alpha) which was not affected by wortmannin. Thus, extracellular Ca entry and MLCK phosphorylation are essential for uterine force production occurring spontaneously or by PGF(2alpha) stimulation. Our data supports the conclusion that the pathway dependent on extracellular Ca entry and MLCK phosphorylation predominates during PGF(2alpha) stimulation but suggests some involvement of an alternative force-producing pathway, presumably Ca-sensitization. PMID:19081211

  14. [Role of nitric oxide in the development of the myocardial contractile reactions in trained animals].

    PubMed

    Shymans'ka, T V; Hoshovs'ka, Iu V; Sahach, V F

    2010-01-01

    Intensive constitutive production of nitric oxide (NO) during physical training improves vasodilatation and heart function. However, it remains unclear how NO takes part in myocardial adaptation to workload, which is accompanied by an increased heart inflow and intracellular calcium content. Using isolated rat heart by Langendorf preparation, we studied myocardial response to gradually increased left ventricular volume (Frank-Starling low) and increasing concentration of Ca2+ in the perfusion solution (from 1.7 mM to 12.5 mM) in trained and untrained rats. It was shown that 4 weeks swimming course improved heart function: heart rate was decreased; contractile activity (dP/dt max) and coronary flow were increased by 20% and 33%, respectively. Equal volume stretching of balloon in left ventricle provoked greater contraction in trained comparing to untrained hearts, demonstrating extended functional reserves after swimming course. Mitochondrial membrane potential was significantly increased in hearts of trained rats. Furthermore, training prevented fast increase of the end diastolic pressure during calcium upload. Mitochondrial factor release due to opening of mitochondrial permeability transition pore (MPTP) in trained hearts was detected at higher concentrations of calcium that reveals extended calcium capacity of mitochondria and lesser sensitivity of MPTP to its inductor-calcium. Blockade of NO synthesis with L-NAME application of (10(-4) M for 15 min) abolished reaction of trained heart during Frank-Starling and calcium upload. Thus, heart adaptation to physical training and extension of functional reserves in heart are provided by endogenous NO production. Key words: nitric oxide, Frank-Starling low, physical training, calcium upload, mitochondrial permeability transition, membrane potential. PMID:21265074

  15. Local Tissue Geometry Determines Contractile Force Generation of Engineered Muscle Networks

    PubMed Central

    Bian, Weining; Juhas, Mark; Pfeiler, Terry W.

    2012-01-01

    The field of skeletal muscle tissue engineering is currently hampered by the lack of methods to form large muscle constructs composed of dense, aligned, and mature myofibers and limited understanding of structure-function relationships in developing muscle tissues. In our previous studies, engineered muscle sheets with elliptical pores (“muscle networks”) were fabricated by casting cells and fibrin gel inside elastomeric tissue molds with staggered hexagonal posts. In these networks, alignment of cells around the elliptical pores followed the local distribution of tissue strains that were generated by cell-mediated compaction of fibrin gel against the hexagonal posts. The goal of this study was to assess how systematic variations in pore elongation affect the morphology and contractile function of muscle networks. We found that in muscle networks with more elongated pores the force production of individual myofibers was not altered, but the myofiber alignment and efficiency of myofiber formation were significantly increased yielding an increase in the total contractile force despite a decrease in the total tissue volume. Beyond a certain pore length, increase in generated contractile force was mainly contributed by more efficient myofiber formation rather than enhanced myofiber alignment. Collectively, these studies show that changes in local tissue geometry can exert both direct structural and indirect myogenic effects on the functional output of engineered muscle. Different hydrogel formulations and pore geometries will be explored in the future to further augment contractile function of engineered muscle networks and promote their use for basic structure-function studies in vitro and, eventually, for efficient muscle repair in vivo. PMID:22115339

  16. Activities and Programs That Improve Children’s Executive Functions

    PubMed Central

    Diamond, Adele

    2014-01-01

    Executive functions (EFs; e.g., reasoning, working memory, and self-control) can be improved. Good news indeed, since EFs are critical for school and job success and for mental and physical health. Various activities appear to improve children’s EFs. The best evidence exists for computer-based training, traditional martial arts, and two school curricula. Weaker evidence, though strong enough to pass peer review, exists for aerobics, yoga, mindfulness, and other school curricula. Here I address what can be learned from the research thus far, including that EFs need to be progressively challenged as children improve and that repeated practice is key. Children devote time and effort to activities they love; therefore, EF interventions might use children’s motivation to advantage. Focusing narrowly on EFs or aerobic activity alone appears not to be as efficacious in improving EFs as also addressing children’s emotional, social, and character development (as do martial arts, yoga, and curricula shown to improve EFs). Children with poorer EFs benefit more from training; hence, training might provide them an opportunity to “catch up” with their peers and not be left behind. Remaining questions include how long benefits of EF training last and who benefits most from which activities. PMID:25328287

  17. Hyperinsulinemia improves ischemic LV function in insulin resistant subjects

    PubMed Central

    2010-01-01

    Background Glucose is a more efficient substrate for ATP production than free fatty acid (FFA). Insulin resistance (IR) results in higher FFA concentrations and impaired myocardial glucose use, potentially worsening ischemia. We hypothesized that metabolic manipulation with a hyperinsulinemic euglycemic clamp (HEC) would affect a greater improvement in left ventricular (LV) performance during dobutamine stress echo (DSE) in subjects with IR. Methods 24 subjects with normal LV function and coronary disease (CAD) awaiting revascularization underwent 2 DSEs. Prior to one DSEs they underwent an HEC, where a primed infusion of insulin (rate 43 mU/m 2/min) was co-administered with 20% dextrose at variable rates to maintain euglycemia. At steady-state the DSE was performed and images of the LV were acquired with tissue Doppler at each stage for offline analysis. Segmental peak systolic velocities (Vs) were recorded, as well as LV ejection fraction (EF). Subjects were then divided into two groups based on their insulin sensitivity during the HEC. Results HEC changed the metabolic environment, suppressing FFAs and thereby increasing glucose use. This resulted in improved LV performance at peak stress, measured by EF (IS group mean difference 5.3 (95% CI 2.5-8) %, p = 0.002; IR group mean difference 8.7 (95% CI 5.8-11.6) %, p < 0.0001) and peak V s in ischemic segments (IS group mean improvement 0.7(95% CI 0.07-1.58) cm/s, p = 0.07; IR group mean improvement 1.0 (95% CI 0.54-1.5) cm/s, p < 0.0001) , that was greater in the subjects with IR. Conclusions Increased myocardial glucose use induced by HEC improves LV function under stress in subjects with CAD and IR. Cardiac metabolic manipulation in subjects with IR is a promising target for future therapy. PMID:20576156

  18. Glucosamine administration during resuscitation improves organ function after trauma hemorrhage.

    PubMed

    Yang, Shaolong; Zou, Lu-Yun; Bounelis, Pam; Chaudry, Irshad; Chatham, John C; Marchase, Richard B

    2006-06-01

    Stress-induced hyperglycemia is necessary for maximal rates of survival after severe hemorrhage; however, the responsible mechanisms are not clear. One consequence of hyperglycemia is an increase in hexosamine biosynthesis, which leads to increases in levels of O-linked attachment of N-acetyl-glucosamine (O-GlcNAc) on nuclear and cytoplasmic proteins. This modification has been shown to lead to improved survival of isolated cells after stress. In view of this, we hypothesized that glucosamine (GlcNH2), which more selectively increases the levels of O-GlcNAc administration after shock, will have salutary effects on organ function after trauma hemorrhage (TH). Fasted male rats that underwent midline laparotomy were bled to a mean arterial blood pressure of 40 mmHg for 90 min and then resuscitated with Ringer lactate (four times the shed blood volume). Administration of 2.5 mL of 150 mmol L GlcNH2 midway during resuscitation improved cardiac output 2-fold compared with controls that received 2.5 mL of 150 mmol L NaCl. GlcNH2 also improved perfusion of various organs systems, including kidney and brain, and attenuated the TH-induced increase in serum levels of IL-6 (902+/-224 vs. 585+/-103 pg mL) and TNF-alpha (540+/-81 vs. 345+/-110 pg mL) (values are mean+/-SD). GlcNH2 administration resulted in significant increase in protein-associated O-GlcNAc in the heart and brain after TH. Thus, GlcNH2 administered during resuscitation improves recovery from TH, as assessed by cardiac function, organ perfusion, and levels of circulating inflammatory cytokines. This protection correlates with enhanced levels of nucleocytoplasmic protein O-GlcNAcylation and suggests that increased O-GlcNAc could be the mechanism that links stress-induced hyperglycemia to improved outcomes. PMID:16721268

  19. Improved Memory Function Two Years After Bariatric Surgery

    PubMed Central

    Alosco, Michael L.; Spitznagel, Mary Beth; Strain, Gladys; Devlin, Michael; Cohen, Ronald; Paul, Robert; Crosby, Ross D.; Mitchell, James E.; Gunstad, John

    2014-01-01

    Objective Obesity is as an independent risk factor for poor neurocognitive outcomes, including Alzheimer’s disease. Bariatric surgery has recently been shown to result in improved memory at 12-weeks post-operatively. However, the long-term effects of bariatric surgery on cognitive function remain unclear. Design and Methods 86 individuals (63 bariatric surgery patients, 23 obese controls) were recruited from a prospective study examining the neurocognitive effects of bariatric surgery. All participants completed self-report measurements and a computerized cognitive test battery prior to surgery and at 12-week and 24-month follow-up; obese controls completed measures at equivalent time points. Results Bariatric surgery patients exhibited high rates of pre-operative cognitive impairments in attention, executive function, memory, and language. Relative to obese controls, repeated measures ANOVA showed improvements in memory from baseline to 12-weeks and 24-months post-operatively (p < .05). Regression analyses controlling for baseline factors revealed that a lower BMI at 24-months demonstrated a trend toward significance for improved memory (β = -.30, p = .075). Conclusion These findings suggest that cognitive benefits of bariatric surgery may extend to 24-months post-operatively. Larger prospective studies with extended follow-up periods are needed to elucidate whether bariatric surgery decreases risk for cognitive decline and possibly the development of dementia. PMID:23625587

  20. Diazoxide accelerates wound healing by improving EPC function.

    PubMed

    Li, Zhang-Peng; Xin, Ru-Juan; Yang, Hong; Jiang, Guo-Jun; Deng, Ya-Ping; Li, Dong-Jie; Shen, Fu-Ming

    2016-01-01

    Endothelial cell dysfunction is the primary cause of microvascular complications in diabetes. Diazoxide enables beta cells to rest by reversibly suppressing glucose-induced insulin secretion by opening ATP-sensitive K+ channels in the beta cells. This study investigated the role of diazoxide in wound healing in mice with streptozotocin (STZ)-induced diabetes and explored the possible mechanisms of its effect. Compared to the controls, mice with STZ-induced diabetes exhibited significantly impaired wound healing. Diazoxide treatment (30 mg/kg/d, intragastrically) for 28 days accelerated wound closure and stimulated angiogenesis in the diabetic mice. Circulating endothelial progenitor cells (EPCs) increased significantly in the diazoxide-treated diabetic mice. The adhesion, migration, and tube formation abilities of bone marrow (BM)-EPCs were impaired by diabetes, and these impairments were improved by diazoxide treatment. The expression of both p53 and TSP-1 increased in diabetic mice compared to that in the controls, and these increases were inhibited significantly by diazoxide treatment. In vitro, diazoxide treatment improved the impaired BM-EPC function and diminished the increased expression of p53 and TSP-1 in cultured BM-EPCs caused by high glucose levels. We conclude that diazoxide improved BM-EPC function in mice with STZ-induced diabetes, possibly via a p53- and TSP-1-dependent pathway. PMID:27100489

  1. Oral zinc supplementation may improve cognitive function in schoolchildren.

    PubMed

    de Moura, José Edson; de Moura, Edna Nubia Oliveira; Alves, Camila Xavier; Vale, Sancha Helena de Lima; Dantas, Márcia Marília Gomes; Silva, Alfredo de Araújo; Almeida, Maria das Graças; Leite, Lúcia Dantas; Brandão-Neto, José

    2013-10-01

    Zinc is an important micronutrient for humans, and zinc deficiency among schoolchildren is deleterious to growth and development, immune competence, and cognitive function. However, the effect of zinc supplementation on cognitive function remains poorly understood. The purpose of our study was to evaluate the effect of oral zinc supplementation (5 mg Zn/day for 3 months) on the Full Scale Intelligence Quotient (FSIQ), Verbal Intelligence Quotient (VIQ), and Performance Intelligence Quotient (PIQ) using a Wechsler Intelligence Scale for Children (WISC-III). We studied 36 schoolchildren aged 6 to 9 years (7.8 ± 1.1) using a nonprobability sampling method. The baseline serum zinc concentrations increased significantly after zinc supplementation (p < 0.0001), with no difference between sexes. Tests were administered under basal conditions before and after zinc supplementation, and there was no difference in FSIQ according to gender or age. The results demonstrated that zinc improved the VIQ only in the Information Subtest (p = 0.009), although the supplementation effects were more significant in relation to the PIQ, as these scores improved for the Picture Completion, Picture Arrangement, Block Design, and Object Assembly Subtests (p = 0.0001, for all subtests). In conclusion, zinc supplementation improved specific cognitive abilities, thereby positively influencing the academic performance of schoolchildren, even those without marginal zinc deficiency. PMID:23892699

  2. Tests of gastric neuromuscular function.

    PubMed

    Parkman, Henry P; Jones, Michael P

    2009-05-01

    Tests of gastric neuromuscular function are used to evaluate patients with symptoms referable to the upper digestive tract. These symptoms can be associated with alterations in the rates of gastric emptying, impaired accommodation, heightened gastric sensation, or alterations in gastric myoelectrical function and contractility. Management of gastric neuromuscular disorders requires an understanding of pathophysiology and treatment options as well as the appropriate use and interpretation of diagnostic tests. These tests include measures of gastric emptying; contractility; electrical activity; regional gastric motility of the fundus, antrum, and pylorus; and tests of sensation and compliance. Tests are also being developed to improve our understanding of the afferent sensory pathways from the stomach to the central nervous system that mediate gastric sensation in health and gastric disorders. This article reviews tests of gastric function and provides a basic description of the tests, the methodologies behind them, descriptions of the physiology that they assess, and their clinical utility. PMID:19293005

  3. Phosphonic Acid-Functionalized Polyurethane Dispersions with Improved Adhesion Properties.

    PubMed

    Breucker, Laura; Landfester, Katharina; Taden, Andreas

    2015-11-11

    A facile route to phosphorus-functionalized polyurethane dispersions (P-PUDs) with improved adhesion properties is presented. (Bis)phosphonic acid moieties serve as adhesion promoting sites that are covalently attached via an end-capping reaction to isocyanate-reactive polyurethane particles under aqueous conditions. The synthetic approach circumvents solubility issues, offers great flexibility in terms of polyurethane composition, and allows for the synthesis of semicrystalline systems with thermomechanical response due to reversible physical cross-linking. Differential scanning calorimetry (DSC) is used to investigate the effect of functionalization on the semicrystallinity. The end-capping conversion was determined via inductively-coupled plasma optical emission spectroscopy (ICP-OES) and was surprisingly found to be almost independent of the stoichiometry of reaction, suggesting an adsorption-dominated process. Particle charge detection (PCD) experiments reveal that a dense surface coverage of phosphonic acid groups can be attained and that, at high functionalization degrees, the phosphonic adhesion moieties are partially dragged inside the colloidal P-PUD particle. Quartz crystal microbalance with dissipation (QCMD) investigations conducted with hydroxyapatite (HAP) and stainless steel sensors as model surfaces show a greatly enhanced affinity of the aqueous P-PUDs and furthermore indicate polymer chain rearrangements and autonomous film formation under wet conditions. Due to their facile synthesis, significantly improved adhesion, and variable film properties, P-PUD systems such as the one described here are believed to be of great interest for multiple applications, e.g., adhesives, paints, anticorrosion, or dentistry. PMID:26491881

  4. Hyperbaric oxygen therapy improves cognitive functioning after brain injury

    PubMed Central

    Liu, Su; Shen, Guangyu; Deng, Shukun; Wang, Xiubin; Wu, Qinfeng; Guo, Aisong

    2013-01-01

    Hyperbaric oxygen therapy has been widely applied and recognized in the treatment of brain injury; however, the correlation between the protective effect of hyperbaric oxygen therapy and changes of metabolites in the brain remains unclear. To investigate the effect and potential mechanism of hyperbaric oxygen therapy on cognitive functioning in rats, we established traumatic brain injury models using Feeney's free falling method. We treated rat models with hyperbaric oxygen therapy at 0.2 MPa for 60 minutes per day. The Morris water maze test for spatial navigation showed that the average escape latency was significantly prolonged and cognitive function decreased in rats with brain injury. After treatment with hyperbaric oxygen therapy for 1 and 2 weeks, the rats’ spatial learning and memory abilities were improved. Hydrogen proton magnetic resonance spectroscopy analysis showed that the N-acetylaspartate/creatine ratio in the hippocampal CA3 region was significantly increased at 1 week, and the N-acetylaspartate/choline ratio was significantly increased at 2 weeks after hyperbaric oxygen therapy. Nissl staining and immunohistochemical staining showed that the number of nerve cells and Nissl bodies in the hippocampal CA3 region was significantly increased, and glial fibrillary acidic protein positive cells were decreased after a 2-week hyperbaric oxygen therapy treatment. Our findings indicate that hyperbaric oxygen therapy significantly improves cognitive functioning in rats with traumatic brain injury, and the potential mechanism is mediated by metabolic changes and nerve cell restoration in the hippocampal CA3 region. PMID:25206655

  5. Contractile dysfunction of the shoulder (rotator cuff tendinopathy): an overview

    PubMed Central

    Littlewood, Chris

    2012-01-01

    It is now over a decade since the features defining a contractile dysfunction of the shoulder were first reported. Since this time, some progress has been made to better understand this mechanical syndrome. In response to these developments, this narrative review will explore current understanding in relation to pathology, diagnosis, treatment, and prognosis of this syndrome with reference to literature specifically relating to contractile dysfunction but also literature relating to rotator cuff tendinopathy where necessary. The review not only identifies the strengths of the mechanical diagnosis and therapy approach with reference to a contractile dysfunction of the shoulder but also identifies where further progress needs to be made. PMID:24179329

  6. Acquisition of the contractile phenotype by murine arterial smooth muscle cells depends on the Mir143/145 gene cluster

    PubMed Central

    Boettger, Thomas; Beetz, Nadine; Kostin, Sawa; Schneider, Johanna; Krüger, Marcus; Hein, Lutz; Braun, Thomas

    2009-01-01

    VSMCs respond to changes in the local environment by adjusting their phenotype from contractile to synthetic, a phenomenon known as phenotypic modulation or switching. Failure of VSMCs to acquire and maintain the contractile phenotype plays a key role in a number of major human diseases, including arteriosclerosis. Although several regulatory circuits that control differentiation of SMCs have been identified, the decisive mechanisms that govern phenotypic modulation remain unknown. Here, we demonstrate that the mouse miR-143/145 cluster, expression of which is confined to SMCs during development, is required for VSMC acquisition of the contractile phenotype. VSMCs from miR-143/145–deficient mice were locked in the synthetic state, which incapacitated their contractile abilities and favored neointimal lesion development. Unbiased high-throughput, quantitative, mass spectrometry–based proteomics using reference mice labeled with stable isotopes allowed identification of miR-143/145 targets; these included angiotensin-converting enzyme (ACE), which might affect both the synthetic phenotype and contractile functions of VSMCs. Pharmacological inhibition of either ACE or the AT1 receptor partially reversed vascular dysfunction and normalized gene expression in miR-143/145–deficient mice. We conclude that manipulation of miR-143/145 expression may offer a new approach for influencing vascular repair and attenuating arteriosclerotic pathogenesis. PMID:19690389

  7. [The action of strophanthin K and beta-acetyldigoxin in vitro on the energy transformation by the contractile protein system of the normal cardiomyocyte].

    PubMed

    Karsanov, N V; Macharashvili, T N; Magaldadze, V A

    1989-12-01

    It was shown in experiments on myocardial fiber bundles (MGFB) from normal heart that strophantin K and beta-acetildigoxin in vitro in concentration of 10(-6) M sharply increased the value of force generated by contractile protein system and its ability to perform work. In this case strophantin K significantly increased energy transformation efficiency. It was concluded that in myocardial contractile protein system a regulator of qualitative and quantitative energy transformation is functioning (a kind of economizer). PMID:2634440

  8. Regulation of contractile vacuole formation and activity in Dictyostelium.

    PubMed

    Du, Fei; Edwards, Kimberly; Shen, Zhouxin; Sun, Binggang; De Lozanne, Arturo; Briggs, Steven; Firtel, Richard A

    2008-08-01

    The contractile vacuole (CV) system is the osmoregulatory organelle required for survival for many free-living cells under hypotonic conditions. We identified a new CV regulator, Disgorgin, a TBC-domain-containing protein, which translocates to the CV membrane at the late stage of CV charging and regulates CV-plasma membrane fusion and discharging. disgorgin(-) cells produce large CVs due to impaired CV-plasma membrane fusion. Disgorgin is a specific GAP for Rab8A-GTP, which also localizes to the CV and whose hydrolysis is required for discharging. We demonstrate that Drainin, a previously identified TBC-domain-containing protein, lies upstream from Disgorgin in this pathway. Unlike Disgorgin, Drainin lacks GAP activity but functions as a Rab11A effector. The BEACH family proteins LvsA and LvsD were identified in a suppressor/enhancer screen of the disgorgin(-) large CV phenotype and demonstrated to have distinct functions in regulating CV formation. Our studies help define the pathways controlling CV function. PMID:18636095

  9. Improvement in cerebral function with treatment of posttraumatic stress disorder.

    PubMed

    Roy, Michael J; Francis, Jennifer; Friedlander, Joshua; Banks-Williams, Lisa; Lande, Raymond G; Taylor, Patricia; Blair, James; McLellan, Jennifer; Law, Wendy; Tarpley, Vanita; Patt, Ivy; Yu, Henry; Mallinger, Alan; Difede, Joann; Rizzo, Albert; Rothbaum, Barbara

    2010-10-01

    Posttraumatic stress disorder (PTSD) and mild traumatic brain injury (mTBI) are signature illnesses of the Iraq and Afghanistan wars, but current diagnostic and therapeutic measures for these conditions are suboptimal. In our study, functional magnetic resonance imaging (fMRI) is used to try to differentiate military service members with: PTSD and mTBI, PTSD alone, mTBI alone, and neither PTSD nor mTBI. Those with PTSD are then randomized to virtual reality exposure therapy or imaginal exposure. fMRI is repeated after treatment and along with the Clinician-Administered PTSD Scale (CAPS) and Clinical Global Impression (CGI) scores to compare with baseline. Twenty subjects have completed baseline fMRI scans, including four controls and one mTBI only; of 15 treated for PTSD, eight completed posttreatment scans. Most subjects have been male (93%) and Caucasian (83%), with a mean age of 34. Significant improvements are evident on fMRI scans, and corroborated by CGI scores, but CAPS scores improvements are modest. In conclusion, CGI scores and fMRI scans indicate significant improvement in PTSD in both treatment arms, though CAPS score improvements are less robust. PMID:20955336

  10. Improvement of digital photoelasticity based on camera response function.

    PubMed

    Chang, Shih-Hsin; Wu, Hsien-Huang P

    2011-09-20

    Studies on photoelasticity have been conducted by many researchers in recent years, and many equations for photoelastic analysis based on digital images were proposed. While these equations were all presented by the light intensity emitted from the analyzer, pixel values of the digital image were actually used in the real calculations. In this paper, a proposal of using relative light intensity obtained by the camera response function to replace the pixel value for photoelastic analysis was investigated. Generation of isochromatic images based on relative light intensity and pixel value were compared to evaluate the effectiveness of the new approach. The results showed that when relative light intensity was used, the quality of an isochromatic image can be greatly improved both visually and quantitatively. We believe that the technique proposed in this paper can also be used to improve the performance for the other types of photoelastic analysis using digital images. PMID:21947044

  11. Improved gene transfer with histidine-functionalized mesoporous silica nanoparticles.

    PubMed

    Brevet, David; Hocine, Ouahiba; Delalande, Anthony; Raehm, Laurence; Charnay, Clarence; Midoux, Patrick; Durand, Jean-Olivier; Pichon, Chantal

    2014-08-25

    Mesoporous silica nanoparticles (MSN) were functionalized with aminopropyltriethoxysilane (MSN-NH2) then L-histidine (MSN-His) for pDNA delivery in cells and in vivo. The complexation of pDNA with MSN-NH2 and MSN-His was first studied with gel shift assay. pDNA complexed with MSN-His was better protected from DNase degradation than with MSN-NH2. An improvement of the transfection efficiency in cells was observed with MSN-His/pDNA compared to MSN-NH2/pDNA, which could be explained by a better internalization of MSN-His. The improvement of the transfection efficiency with MSN-His was also observed for gene transfer in Achilles tendons in vivo. PMID:24853464

  12. Improving nonlinear modeling capabilities of functional link adaptive filters.

    PubMed

    Comminiello, Danilo; Scarpiniti, Michele; Scardapane, Simone; Parisi, Raffaele; Uncini, Aurelio

    2015-09-01

    The functional link adaptive filter (FLAF) represents an effective solution for online nonlinear modeling problems. In this paper, we take into account a FLAF-based architecture, which separates the adaptation of linear and nonlinear elements, and we focus on the nonlinear branch to improve the modeling performance. In particular, we propose a new model that involves an adaptive combination of filters downstream of the nonlinear expansion. Such combination leads to a cooperative behavior of the whole architecture, thus yielding a performance improvement, particularly in the presence of strong nonlinearities. An advanced architecture is also proposed involving the adaptive combination of multiple filters on the nonlinear branch. The proposed models are assessed in different nonlinear modeling problems, in which their effectiveness and capabilities are shown. PMID:26057613

  13. Improving Network Structure can lead to Functional Failures.

    PubMed

    Pade, Jan Philipp; Pereira, Tiago

    2015-01-01

    In many real-world networks the ability to synchronize is a key property for their performance. Recent work on undirected networks with diffusive interaction revealed that improvements in the network connectivity such as making the network more connected and homogeneous enhances synchronization. However, real-world networks have directed and weighted connections. In such directed networks, understanding the impact of structural changes on the network performance remains a major challenge. Here, we show that improving the structure of a directed network can lead to a failure in the network function. For instance, introducing new links to reduce the minimum distance between nodes can lead to instabilities in the synchronized motion. This effect only occurs in directed networks. Our results allow to identify the dynamical importance of a link and thereby have a major impact on the design and control of directed networks. PMID:25989294

  14. A Short Executive Function Training Program Improves Preschoolers’ Working Memory

    PubMed Central

    Blakey, Emma; Carroll, Daniel J.

    2015-01-01

    Cognitive training has been shown to improve executive functions (EFs) in middle childhood and adulthood. However, fewer studies have targeted the preschool years—a time when EFs undergo rapid development. The present study tested the effects of a short four session EF training program in 54 four-year-olds. The training group significantly improved their working memory from pre-training relative to an active control group. Notably, this effect extended to a task sharing few surface features with the trained tasks, and continued to be apparent 3 months later. In addition, the benefits of training extended to a measure of mathematical reasoning 3 months later, indicating that training EFs during the preschool years has the potential to convey benefits that are both long-lasting and wide-ranging. PMID:26635710

  15. Mesenchymal Stromal Cells Improve Renovascular Function in Polycystic Kidney Disease.

    PubMed

    Franchi, Federico; Peterson, Karen M; Xu, Rende; Miller, Brent; Psaltis, Peter J; Harris, Peter C; Lerman, Lilach O; Rodriguez-Porcel, Martin

    2015-01-01

    Polycystic kidney disease (PKD) is a common cause of end-stage renal failure, for which there is no accepted treatment. Progenitor and stem cells have been shown to restore renal function in a model of renovascular disease, a disease that shares many features with PKD. The objective of this study was to examine the potential of adult stem cells to restore renal structure and function in PKD. Bone marrow-derived mesenchymal stromal cells (MSCs, 2.5 × 10(5)) were intrarenally infused in 6-week-old PCK rats. At 10 weeks of age, PCK rats had an increase in systolic blood pressure (SBP) versus controls (126.22 ± 2.74 vs. 116.45 ± 3.53 mmHg, p < 0.05) and decreased creatinine clearance (3.76 ± 0.31 vs. 6.10 ± 0.48 µl/min/g, p < 0.01), which were improved in PKD animals that received MSCs (SBP: 114.67 ± 1.34 mmHg, and creatinine clearance: 4.82 ± 0.24 µl/min/g, p = 0.001 and p = 0.003 vs. PKD, respectively). MSCs preserved vascular density and glomeruli diameter, measured using microcomputed tomography. PCK animals had increased urine osmolality (843.9 ± 54.95 vs. 605.6 ± 45.34 mOsm, p < 0.01 vs. control), which was improved after MSC infusion and not different from control (723.75 ± 56.6 mOsm, p = 0.13 vs. control). Furthermore, MSCs reduced fibrosis and preserved the expression of proangiogenic molecules, while cyst size and number were unaltered by MSCs. Delivery of exogenous MSCs improved vascular density and renal function in PCK animals, and the benefit was observed up to 4 weeks after a single infusion. Cell-based therapy constitutes a novel approach in PKD. PMID:25290249

  16. Megacystis microcolon intestinal hypoperistalsis syndrome: evidence of a primary myocellular defect of contractile fiber synthesis.

    PubMed

    Ciftci, A O; Cook, R C; van Velzen, D

    1996-12-01

    Two infant boys with megacystis microcolon intestinal hypoperistalsis syndrome (MMIHS) are reported. Presenting with neonatal intestinal obstruction, they underwent laparotomies that showed megacystis, microcolon, and aperistaltic shortened small bowel without any mechanical obstruction. Patient 1 gradually improved and is developing normally at home, on a normal diet without genitourinary or gastrointestinal complaints (now 11 years old). Patient 2, who underwent vesicoamniotic drainage antenatally, never developed adequate gastrointestinal or genitourinary function in spite of appropriate diversion and pharmacologic support. He showed progressive deterioration and died at the age of 7 months. Detailed histo-immuno- and ultrastructural pathology assessment, although confirming results in the existing literature in some aspects, showed previously unreported neuronal dysplastic changes associated with increased laminin and fibronectin. Although patient 1 showed ultrastructural features of vacuolar degeneration of smooth muscle as reported in the literature, patient 2 showed ultrastructural and histochemical evidence of excessive smooth muscle cell glycogen storage with severely reduced contractile fibres displaced to the extreme periphery of the cells, suggesting a fundamental defect of glycogen-energy utilization. A deficiency of fiber synthesis as the alternative primary defect is discussed. In both cases, a two-step genetic defect may explain the variability in clinical outcome and pathological findings. PMID:8986997

  17. Velocity-based cardiac contractility personalization from images using derivative-free optimization.

    PubMed

    Wong, Ken C L; Sermesant, Maxime; Rhode, Kawal; Ginks, Matthew; Rinaldi, C Aldo; Razavi, Reza; Delingette, Hervé; Ayache, Nicholas

    2015-03-01

    Model personalization is a key aspect for biophysical models to impact clinical practice, and cardiac contractility personalization from medical images is a major step in this direction. Existing gradient-based optimization approaches show promising results of identifying the maximum contractility from images, but the contraction and relaxation rates are not accounted for. A main reason is the limited choices of objective functions when their gradients are required. For complicated cardiac models, analytical evaluations of gradients are very difficult if not impossible, and finite difference approximations are computationally expensive and may introduce numerical difficulties. By removing such limitations with derivative-free optimization, we found that a velocity-based objective function can properly identify regional maximum contraction stresses, contraction rates, and relaxation rates simultaneously with intact model complexity. Experiments on synthetic data show that the parameters are better identified using the velocity-based objective function than its position-based counterpart, and the proposed framework is insensitive to initial parameters with the adopted derivative-free optimization algorithm. Experiments on clinical data show that the framework can provide personalized contractility parameters which are consistent with the underlying physiologies of the patients and healthy volunteers. PMID:25553554

  18. Active robotic training improves locomotor function in a stroke survivor

    PubMed Central

    2012-01-01

    Background Clinical outcomes after robotic training are often not superior to conventional therapy. One key factor responsible for this is the use of control strategies that provide substantial guidance. This strategy not only leads to a reduction in volitional physical effort, but also interferes with motor relearning. Methods We tested the feasibility of a novel training approach (active robotic training) using a powered gait orthosis (Lokomat) in mitigating post-stroke gait impairments of a 52-year-old male stroke survivor. This gait training paradigm combined patient-cooperative robot-aided walking with a target-tracking task. The training lasted for 4-weeks (12 visits, 3 × per week). The subject’s neuromotor performance and recovery were evaluated using biomechanical, neuromuscular and clinical measures recorded at various time-points (pre-training, post-training, and 6-weeks after training). Results Active robotic training resulted in considerable increase in target-tracking accuracy and reduction in the kinematic variability of ankle trajectory during robot-aided treadmill walking. These improvements also transferred to overground walking as characterized by larger propulsive forces and more symmetric ground reaction forces (GRFs). Training also resulted in improvements in muscle coordination, which resembled patterns observed in healthy controls. These changes were accompanied by a reduction in motor cortical excitability (MCE) of the vastus medialis, medial hamstrings, and gluteus medius muscles during treadmill walking. Importantly, active robotic training resulted in substantial improvements in several standard clinical and functional parameters. These improvements persisted during the follow-up evaluation at 6 weeks. Conclusions The results indicate that active robotic training appears to be a promising way of facilitating gait and physical function in moderately impaired stroke survivors. PMID:22906099

  19. Note: Work function change measurement via improved Anderson method

    SciTech Connect

    Sabik, A. Gołek, F.; Antczak, G.

    2015-05-15

    We propose the modification to the Anderson method of work function change (Δϕ) measurements. In this technique, the kinetic energy of the probing electrons is already low enough for non-destructive investigation of delicate molecular systems. However, in our implementation, all electrodes including filament of the electron gun are polarized positively. As a consequence, electron bombardment of any elements of experimental system is eliminated. Our modification improves cleanliness of the ultra-high vacuum system. As an illustration of the solution capabilities, we present Δϕ of the Ag(100) surface induced by cobalt phthalocyanine layers.

  20. Note: Work function change measurement via improved Anderson method.

    PubMed

    Sabik, A; Gołek, F; Antczak, G

    2015-05-01

    We propose the modification to the Anderson method of work function change (Δϕ) measurements. In this technique, the kinetic energy of the probing electrons is already low enough for non-destructive investigation of delicate molecular systems. However, in our implementation, all electrodes including filament of the electron gun are polarized positively. As a consequence, electron bombardment of any elements of experimental system is eliminated. Our modification improves cleanliness of the ultra-high vacuum system. As an illustration of the solution capabilities, we present Δϕ of the Ag(100) surface induced by cobalt phthalocyanine layers. PMID:26026572

  1. Improving Convergence of Backpropagation Learning using Exponential Cost Function

    NASA Astrophysics Data System (ADS)

    Kamruzzaman, Joarder

    Backpropagation, one of the most popular learning algorithms in multi-layered feedforward neural networks, suffers from the drawback of slow convergence. Several modifications have been proposed to accelerate the learning process using different techniques. In this paper, a new cost function expressed as exponential of sum-squared or Log-likelihood is proposed. Weight update using this modification varies the learning rate parameter dynamically during training as opposed to constant learning rate parameter used in standard Backpropagation. Simulation results with different problems demonstrate significant improvement in the learning speed of Backpropagation algorithm.

  2. Short-term improvement of masticatory function after implant restoration

    PubMed Central

    2015-01-01

    Purpose Dental implants present several advantages over other tooth replacement options. However, there has been little research on masticatory function in relation to implant treatment. Therefore, the aim of the present study was to evaluate the improvement of masticatory function two weeks after implant restoration. Methods Masticatory ability was evaluated with the subjective food intake ability (FIA) and objective mixing ability index (MAI) methods. Fifty-four subjects with first and second missing molars completed the study. The subjects were asked to complete a self-reported questionnaire about 30 different food items, and to chew wax samples 10 times both before and two weeks after implant restoration. A total of 108 waxes were analyzed with an image analysis program. Results Dental implant restoration for lost molar teeth on one side increased the FIA score by 9.0% (P<0.0001). The MAI score also increased, by 14.3% after implant restoration (P<0.0001). Comparison between the good and poor mastication groups, which were subdivided based on the median MAI score before implant restoration, showed that the FIA score of the poor group was enhanced 1.1-fold while its MAI score was enhanced 2.0-fold two weeks after an implant surgery. Conclusions Using the FIA and MAI assessment methods, this study showed that masticatory function was improved two weeks after implant restoration. In particular, the enhancement of masticatory function by implant restoration was greater in patients with relatively poor initial mastication than in those with good initial mastication. PMID:26734490

  3. Astym therapy improves function and range of motion following mastectomy

    PubMed Central

    Davies, Claire C; Brockopp, Dorothy; Moe, Krista

    2016-01-01

    Hypersensitive scar tissue formation along the incision line and drain site is a common side effect following mastectomy. If this scar tissue is not addressed, it can lead to decreased flexibility and function in the involved upper quadrant. Astym® treatment is a new approach to soft tissue injuries, and is evidenced in animal studies to promote the healing and regeneration of soft tissues. It has also been found to reduce pain and increase function in people with soft tissue dysfunction. The aim of Astym treatment is to engage the regenerative mechanisms of the body in order to resorb scar tissue, stimulate tissue turnover, and regenerate soft tissues. Handheld instrumentation is applied topically to locate and treat the underlying dysfunctional soft tissue through specific protocols for the application of particular pressures and shear forces. The purpose of this study was to examine the effects of Astym treatment on activities of daily living in women who had undergone a mastectomy following a diagnosis of breast cancer. A quasi-experiment involving 40 women, following a mastectomy, evaluated five outcome measures pre- and post-Astym treatment. All five measurement scores: Disabilities of the Arm, Shoulder, and Hand Outcome Measure; a clothing questionnaire on their ability to wear a bra; Patient-Specific Functional Scale; active range of motion of shoulder flexion; and active range of motion of abduction were also measured and all demonstrated significant changes. In this study, Astym treatment improved active range of motion in the involved quadrant and also improved function in patients following a mastectomy. PMID:27022302

  4. Astym therapy improves function and range of motion following mastectomy.

    PubMed

    Davies, Claire C; Brockopp, Dorothy; Moe, Krista

    2016-01-01

    Hypersensitive scar tissue formation along the incision line and drain site is a common side effect following mastectomy. If this scar tissue is not addressed, it can lead to decreased flexibility and function in the involved upper quadrant. Astym(®) treatment is a new approach to soft tissue injuries, and is evidenced in animal studies to promote the healing and regeneration of soft tissues. It has also been found to reduce pain and increase function in people with soft tissue dysfunction. The aim of Astym treatment is to engage the regenerative mechanisms of the body in order to resorb scar tissue, stimulate tissue turnover, and regenerate soft tissues. Handheld instrumentation is applied topically to locate and treat the underlying dysfunctional soft tissue through specific protocols for the application of particular pressures and shear forces. The purpose of this study was to examine the effects of Astym treatment on activities of daily living in women who had undergone a mastectomy following a diagnosis of breast cancer. A quasi-experiment involving 40 women, following a mastectomy, evaluated five outcome measures pre- and post-Astym treatment. All five measurement scores: Disabilities of the Arm, Shoulder, and Hand Outcome Measure; a clothing questionnaire on their ability to wear a bra; Patient-Specific Functional Scale; active range of motion of shoulder flexion; and active range of motion of abduction were also measured and all demonstrated significant changes. In this study, Astym treatment improved active range of motion in the involved quadrant and also improved function in patients following a mastectomy. PMID:27022302

  5. Remote sensing of vegetation ecophysiological function for improved hydrologic prediction

    NASA Astrophysics Data System (ADS)

    Drewry, D.; Ruddell, B. L.

    2014-12-01

    Land surface hydrology in vegetated landscapes is strongly controlled by ecophysiological function. The coupling between photosynthesis, stomatal dynamics and leaf energy balance fundamentally links the hydrologic and carbon cycles, and provides a basis for examining the utility of observations of functional plant traits for hydrologic prediction. Here we explore the potential of solar induced fluorescence (SIF) and thermal infrared (TIR) remote sensing observations to improve the accuracy and reduce the uncertainty in hydrologic prediction. While SIF represents an emission of radiation associated with photosynthesis, TIR provides information on foliage temperature and is related to stomatal function and water stress. A set of remote observing system simulation experiments are conducted to quantify the value of remotely sensed observations of SIF and TIR when assimilated into a detailed vegetation biophysical model. The MLCan model discretizes a dense plant canopy to resolve vertical variation in photosynthesis, water vapor and energy exchange. Here we present extensions to MLCan that allow for direct computation of the canopy emission of both SIF and TIR. The detailed representation of the physical environment and biological functioning of structurally complex canopies makes MLCan an ideal simulation tool for exploring the impact of these two unique, and potentially synergistic observables. This work specifically addresses remote sensing capabilities on both recently launched (OCO-2) and near-term (ECOSTRESS) satellite platforms. We contrast the information gained through the assimilation of SIF and TIR observations to that of the assimilation of data related to physical states such as soil moisture and leaf area index.

  6. Considerations for Contractile Electroactive Polymeric Materials and Actuators

    SciTech Connect

    Rasmussen, Lenore; Erickson, Carl J.; Meixler, Lewis D.; Ascione, George; Gentile, Charles A.; Tilson, Charles; Bernasek, Stephen L.; Abelev, Esta

    2009-06-16

    Ras Labs produces electroactive polymer (EAP) based materials and actuators that bend, swell, ripple and now contract (new development) with low electric input. This is an important attribute because of the ability of contraction to produce life-like motion. The mechanism of contraction is not well understood. Radionuclide-labeled experiments were conducted to follow the movement of electrolytes and water in these EAPs when activated. Extreme temperature experiments were performed on the contractile EAPs with very favorable results. One of the biggest challenges in developing these actuators, however, is the electrode-EAP interface because of the pronounced movement of the EAP. Plasma treatments of metallic electrodes were investigated in order to improve the attachment of the embedded electrodes to the EAP material. Surface analysis, adhesive testing, and mechanical testing were conducted to test metal surfaces and metal-polymer interfaces. The nitrogen plasma treatment of titanium produced a strong metal-polymer interface; however, oxygen plasma treatment of both stainless steel and titanium produced even stronger metal-polymer interfaces. Plasma treatment of the electrodes allows for the embedded electrodes and the EAP material of the actuator to work and move as a unit, with no detachment, by significantly improving the metal-polymer interface.

  7. Geometrical Origins of Contractility in Disordered Actomyosin Networks

    NASA Astrophysics Data System (ADS)

    Lenz, Martin

    2014-10-01

    Movement within eukaryotic cells largely originates from localized forces exerted by myosin motors on scaffolds of actin filaments. Although individual motors locally exert both contractile and extensile forces, large actomyosin structures at the cellular scale are overwhelmingly contractile, suggesting that the scaffold serves to favor contraction over extension. While this mechanism is well understood in highly organized striated muscle, its origin in disordered networks such as the cell cortex is unknown. Here, we develop a mathematical model of the actin scaffold's local two- or three-dimensional mechanics and identify four competing contraction mechanisms. We predict that one mechanism dominates, whereby local deformations of the actin break the balance between contraction and extension. In this mechanism, contractile forces result mostly from motors plucking the filaments transversely rather than buckling them longitudinally. These findings shed light on recent in vitro experiments and provide a new geometrical understanding of contractility in the myriad of disordered actomyosin systems found in vivo.

  8. Maca (L. meyenii) for improving sexual function: a systematic review

    PubMed Central

    2010-01-01

    Background Maca (Lepidium meyenii) is an Andean plant of the brassica (mustard) family. Preparations from maca root have been reported to improve sexual function. The aim of this review was to assess the clinical evidence for or against the effectiveness of the maca plant as a treatment for sexual dysfunction. Methods We searched 17 databases from their inception to April 2010 and included all randomised clinical trials (RCTs) of any type of maca compared to a placebo for the treatment of healthy people or human patients with sexual dysfunction. The risk of bias for each study was assessed using Cochrane criteria, and statistical pooling of data was performed where possible. The selection of studies, data extraction, and validations were performed independently by two authors. Discrepancies were resolved through discussion by the two authors. Results Four RCTs met all the inclusion criteria. Two RCTs suggested a significant positive effect of maca on sexual dysfunction or sexual desire in healthy menopausal women or healthy adult men, respectively, while the other RCT failed to show any effects in healthy cyclists. The further RCT assessed the effects of maca in patients with erectile dysfunction using the International Index of Erectile Dysfunction-5 and showed significant effects. Conclusion The results of our systematic review provide limited evidence for the effectiveness of maca in improving sexual function. However, the total number of trials, the total sample size, and the average methodological quality of the primary studies were too limited to draw firm conclusions. More rigorous studies are warranted. PMID:20691074

  9. Does L-carnitine improve endothelial function in hemodialysis patients?

    PubMed Central

    Sabri, Mohammad Reza; Fahimi, Farnaz; Hajialiasgar, Soheila; Etminan, Abbas; Nazemi, Sarir; Salehi, Farzaneh

    2012-01-01

    Background: Atherosclerosis is the leading cause of death in hemodialysis patients. These patients are also very prone to L-carnitine deficiency due to kidney disease. In this clinical trial, we investigated the effect of oral L-carnitine on endothelial function of these patients. Materials ans Methods: We studied 31 adult chronic hemodialysis patients in our center and divided them into two groups. The first group (n = 20) received 1500 mg/dialysis interval (every other day) oral L-carnitine. The control group (n = 11) received placebo for one month. Ultrasonographic measurements of flow mediated dilation and carotid intima-media thickness were performed before and after one month of L-carnitine and placebo therapy. Results: This study showed that after one month of L-carnitine or placebo therapy there was no significant improvement in flow mediated dilation (p = 0.80 and p = 0.59, respectively) or decrease in carotid intima-media thickness (p = 0.12 and p = 0.50, respectively). Conclusions: Our study revealed that one month of oral L-carnitine therapy did not improve endothelial function in hemodialysis patients. Long-term studies with large sample size using intravenous form and higher doses of the drug are required to clarify the questionable role of L-carnitine in hemodialysis patients. PMID:23626603

  10. Traditional Japanese Medicine Daikenchuto Improves Functional Constipation in Poststroke Patients

    PubMed Central

    Numata, Takehiro; Takayama, Shin; Tobita, Muneshige; Ishida, Shuichi; Katayose, Dai; Shinkawa, Mitsutoshi; Oikawa, Takashi; Aonuma, Takanori; Kaneko, Soichiro; Tanaka, Junichi; Kanemura, Seiki; Iwasaki, Koh; Ishii, Tadashi; Yaegashi, Nobuo

    2014-01-01

    Poststroke patients with functional constipation, assessed by the Rome III criteria, from 6 hospitals were recruited in a study on the effects of the traditional Japanese medicine Daikenchuto (DKT) on constipation. Thirty-four patients (17 men and 17 women; mean age: 78.1 ± 11.6 years) were randomly assigned to 2 groups; all patients received conventional therapy for constipation, and patients in the DKT group received 15 g/day of DKT for 4 weeks. Constipation scoring system (CSS) points and the gas volume score (GVS) (the measure of the intestinal gas volume calculated from plain abdominal radiographs) were recorded before and after a 4-week observation period. The total score on the CSS improved significantly in the DKT group compared to the control (P < 0.01). In addition, scores for some CSS subcategories (frequency of bowel movements, feeling of incomplete evacuation, and need for enema/disimpaction) significantly improved in the DKT group (P < 0.01, P = 0.049, and P = 0.03, resp.). The GVS was also significantly reduced in the DKT group compared to the control (P = 0.03). DKT in addition to conventional therapy is effective in treating functional constipation in poststroke patients. This study was a randomized controlled trial and was registered in the UMIN Clinical Trial Registry (no. UMIN000007393). PMID:25089144

  11. Improved CLARAty Functional-Layer/Decision-Layer Interface

    NASA Technical Reports Server (NTRS)

    Estlin, Tara; Rabideau, Gregg; Gaines, Daniel; Johnston, Mark; Chouinard, Caroline; Nessnas, Issa; Shu, I-Hsiang

    2008-01-01

    Improved interface software for communication between the CLARAty Decision and Functional layers has been developed. [The Coupled Layer Architecture for Robotics Autonomy (CLARAty) was described in Coupled-Layer Robotics Architecture for Autonomy (NPO-21218), NASA Tech Briefs, Vol. 26, No. 12 (December 2002), page 48. To recapitulate: the CLARAty architecture was developed to improve the modularity of robotic software while tightening coupling between planning/execution and basic control subsystems. Whereas prior robotic software architectures typically contained three layers, the CLARAty contains two layers: a decision layer (DL) and a functional layer (FL).] Types of communication supported by the present software include sending commands from DL modules to FL modules and sending data updates from FL modules to DL modules. The present software supplants prior interface software that had little error-checking capability, supported data parameters in string form only, supported commanding at only one level of the FL, and supported only limited updates of the state of the robot. The present software offers strong error checking, and supports complex data structures and commanding at multiple levels of the FL, and relative to the prior software, offers a much wider spectrum of state-update capabilities.

  12. Improvement of renal function after opening occluded atherosclerotic renal arteries.

    PubMed

    Kanamori, Hiroshi; Toma, Masanao; Fukatsu, Atsushi

    2009-09-01

    Percutaneous transluminal renal angioplasty (PTRA) with stenting has been effective in the control of hypertension, renal function and pulmonary edema caused by atherosclerotic renal artery stenosis (ARAS). However, concerning the viability of renal function, this procedure has not been fully established, especially in the presence of renal atrophy or severe renal parenchymal disease. We report a dramatically improved case of acute renal failure caused by acute worsening ARAS treated by stenting. A 72-year-old female was admitted for accelerated renal dysfunction (serum ceatinine; 1.2-2.3 mg/dl) and hypertension (190/100 mmHg). At 10 days after admission, the patient's serum ceatinine increased to 6.7 mg/dl, her pulmonary edema was exaggerated and hemodialysis was required. Ultrasonography showed bilateral high-echoic kidneys, but no apparent finding of renal artery stenosis (RAS). At day 15, computed tomographic angiography indicated bilateral ostial RAS. Renal angiography demonstrated total occlusion of the right and severe (90%) disease in the left. ARAS was diagnosed by intravascular ultrasonography. The guidewire was inserted in both renal arteries, PTRA with stenting was performed in the right and a stent was directly implanted in the left. Immediately, each kidney enlarged to almost normal size, leading to satisfactory urination. She was released from hemodialysis the next day since her serum creatinine was normal and the pulmonary edema was improved. Although there is still no reliable prognostic factor including resistive index or kidney size, it is important that PTRA with stenting in ARAS should be considered in a case of accelerated renal dysfunction because of the possible improvement. PMID:19726830

  13. Valuing preferences over stormwater management outcomes including improved hydrologic function

    NASA Astrophysics Data System (ADS)

    LondoñO Cadavid, Catalina; Ando, Amy W.

    2013-07-01

    Stormwater runoff causes environmental problems such as flooding, soil erosion, and water pollution. Conventional stormwater management has focused primarily on flood reduction, while a new generation of decentralized stormwater solutions yields ancillary benefits such as healthier aquatic habitat, improved surface water quality, and increased water table recharge. Previous research has estimated values for flood reduction from stormwater management, but no estimates exist for the willingness to pay (WTP) for some of the other environmental benefits of alternative approaches to stormwater control. This paper uses a choice experiment survey of households in Champaign-Urbana, Illinois, to estimate the values of several attributes of stormwater management outcomes. We analyzed data from 131 surveyed households in randomly selected neighborhoods. We find that people value reduced basement flooding more than reductions in yard or street flooding, but WTP for basement flood reduction in the area only exists if individuals are currently experiencing significant flooding themselves. Citizens value both improved water quality and improved hydrologic function and aquatic habitat from runoff reduction. Thus, widespread investment in low impact development stormwater solutions could have very large total benefits, and stormwater managers should be wary of policies and infrastructure plans that reduce flooding at the expense of water quality and aquatic habitat.

  14. Cellular Architecture Regulates Collective Calcium Signaling and Cell Contractility

    PubMed Central

    Hoying, James B.; Deymier, Pierre A.; Zhang, Donna D.; Wong, Pak Kin

    2016-01-01

    A key feature of multicellular systems is the ability of cells to function collectively in response to external stimuli. However, the mechanisms of intercellular cell signaling and their functional implications in diverse vascular structures are poorly understood. Using a combination of computational modeling and plasma lithography micropatterning, we investigate the roles of structural arrangement of endothelial cells in collective calcium signaling and cell contractility. Under histamine stimulation, endothelial cells in self-assembled and microengineered networks, but not individual cells and monolayers, exhibit calcium oscillations. Micropatterning, pharmacological inhibition, and computational modeling reveal that the calcium oscillation depends on the number of neighboring cells coupled via gap junctional intercellular communication, providing a mechanistic basis of the architecture-dependent calcium signaling. Furthermore, the calcium oscillation attenuates the histamine-induced cytoskeletal reorganization and cell contraction, resulting in differential cell responses in an architecture-dependent manner. Taken together, our results suggest that endothelial cells can sense and respond to chemical stimuli according to the vascular architecture via collective calcium signaling. PMID:27196735

  15. Contractile vacuole complex--its expanding protein inventory.

    PubMed

    Plattner, Helmut

    2013-01-01

    The contractile vacuole complex (CVC) of some protists serves for the osmotic equilibration of water and ions, notably Ca(2+), by chemiosmotic exploitation of a H(+) gradient generated by the organelle-resident V-type H(+)-ATPase. Ca(2+) is mostly extruded, but there is also some reflux into the cytosol via Ca(2+)-release channels. Most data available are from Dictyostelium and Paramecium. In Paramecium, the major parts of CVC contain several v-/R-SNARE (synaptobrevins) and t-/Q-SNARE (syntaxins) proteins. This is complemented by Rab-type GTPases (shown in Tetrahymena) and exocyst components (Chlamydomonas). All this reflects a multitude of membrane interactions and fusion processes. Ca(2+)/H(+) and other exchangers are to be postulated, as are aquaporins and mechanosensitive Ca(2+) channels. From the complexity of the organelle, many more proteins may be expected. For instance, the pore is endowed with its own set of proteins. We may now envisage the regulation of membrane dynamics (reversible tubulation) and the epigenetic control of organelle shape, size and positioning. New aspects about organelle function and biogenesis are sketched in Section 7. The manifold regulators currently known from CVC suggest the cooperation of widely different mechanisms to maintain its dynamic function and to drive its biogenesis. PMID:24016530

  16. Modeling the dispersion effects of contractile fibers in smooth muscles

    NASA Astrophysics Data System (ADS)

    Murtada, Sae-Il; Kroon, Martin; Holzapfel, Gerhard A.

    2010-12-01

    Micro-structurally based models for smooth muscle contraction are crucial for a better understanding of pathological conditions such as atherosclerosis, incontinence and asthma. It is meaningful that models consider the underlying mechanical structure and the biochemical activation. Hence, a simple mechanochemical model is proposed that includes the dispersion of the orientation of smooth muscle myofilaments and that is capable to capture available experimental data on smooth muscle contraction. This allows a refined study of the effects of myofilament dispersion on the smooth muscle contraction. A classical biochemical model is used to describe the cross-bridge interactions with the thin filament in smooth muscles in which calcium-dependent myosin phosphorylation is the only regulatory mechanism. A novel mechanical model considers the dispersion of the contractile fiber orientations in smooth muscle cells by means of a strain-energy function in terms of one dispersion parameter. All model parameters have a biophysical meaning and may be estimated through comparisons with experimental data. The contraction of the middle layer of a carotid artery is studied numerically. Using a tube the relationships between the internal pressure and the stretches are investigated as functions of the dispersion parameter, which implies a strong influence of the orientation of smooth muscle myofilaments on the contraction response. It is straightforward to implement this model in a finite element code to better analyze more complex boundary-value problems.

  17. Modification of aortic contractility in the cardiomyopathic hamster.

    PubMed Central

    Dumont, E. C.; Lambert, C.; Lamontagne, D.

    1996-01-01

    1. The functional arterial response in the cardiomyopathic hamster compared with inbred control, was investigated in thoracic aortae. For this purpose, vessels were cut into 6-mm rings and mounted in 20-ml organ baths. 2. In a first experimental series, the function of the endothelium was evaluated. Dose-response curves to acetylcholine (0.1 nM-10 microM) on phenylephrine (0.3 microM)-preconstricted rings of cardiomyopathic hamsters and inbred age-matched controls were comparable (log[EC50] of -7.08 +/- 0.12 and -7.18 +/- 0.12, respectively; n = 4). 3. Changes in contractility of cardiomyopathic hamster endothelium-denuded aortae were investigated. Dose-response curves to phenylephrine (1 nM-0.1 mM), angiotensin II (10 pM-0.3 microM), 5-hydroxytryptamine (5-HT) (1 nM-0.1 mM) and KCl (1 mM-0.1 M) were performed. Increased sensitivity in cardiomyopathic hamster aortae, compared to controls, was observed with phenylephrine (log[EC50] of -7.25 +/- 0.05 and -6.83 +/- 0.05, respectively, n = 6, P < 0.001) and angiotensin II (log[EC50] of -8.67 +/- 0.07 and -8.26 +/- 0.06, respectively, n = 6, P = 0.001) but not with 5-HT or KCl. A decreased maximum response in cardiomyopathic, compared to control, was observed with 5-HT (1.28 +/- 0.06 g vs 1.56 +/- 0.07 g, respectively, n = 6, P = 0.03). Comparable results were found in aortae with an intact endothelium. 4. No difference in the maximum contractile response to the G-protein activator, NaF (3, 10 and 30 mM) was observed in either group of animals. 5. Phorbol 12-myristate 13-acetate (PMA, 1-10 microM) was used to assess changes in the activity of protein kinase C (PKC). Contractility to PMA was increased in cardiomyopathic hamster aortae compared to controls (0.22 +/- 0.02 g vs 0.07 +/- 0.03 g at 3 microM, respectively, n = 6, P = 0.003). 6. Finally, cardiomyopathic hamsters aortae were found to be less sensitive when exposed to increasing concentrations of Ca2+ (10 microM-1 mM) in KCl-depolarized rings (0.58 +/- 0.04 g in

  18. Intestinal barrier function in neonatal foals: options for improvement.

    PubMed

    Vendrig, Johannes C; Fink-Gremmels, Johanna

    2012-07-01

    Gastrointestinal defence in the new-born is limited in comparison to adults, due to an immature epithelial barrier function and deficits in both innate and adaptive immune responses. Consequently, neonates (including foals) are at increased risk of disturbance to mucosal homeostasis during initial intestinal colonisation that may lead to excessive inflammation and bacterial translocation into the bloodstream, resulting in septicaemia. Bacterial recognition by Pattern Recognition Receptors (PRRs) and their downstream regulation of cytokine release have been shown to be pivotal for gastrointestinal mucosal homeostasis and the development of a functional intestinal barrier. Evidence suggests that selective PRR agonists limit the inflammatory responses and improve epithelial barrier function. Milk, and in particular colostrum, contain a broad array of oligosaccharides which seem to act as PRR agonists. This class of compounds forms a source for new dietary formulas that may orchestrate gut colonisation by the commensal flora in the early phase of life and so reduce the risks of inflammation and pathogen invasion. PMID:22377327

  19. Improving outcome of sensorimotor functions after traumatic spinal cord injury

    PubMed Central

    Dietz, Volker

    2016-01-01

    In the rehabilitation of a patient suffering a spinal cord injury (SCI), the exploitation of neuroplasticity is well established. It can be facilitated through the training of functional movements with technical assistance as needed and can improve outcome after an SCI. The success of such training in individuals with incomplete SCI critically depends on the presence of physiological proprioceptive input to the spinal cord leading to meaningful muscle activations during movement performances. Some actual preclinical approaches to restore function by compensating for the loss of descending input to spinal networks following complete/incomplete SCI are critically discussed in this report. Electrical and pharmacological stimulation of spinal neural networks is still in the experimental stage, and despite promising repair studies in animal models, translations to humans up to now have not been convincing. It is possible that a combination of techniques targeting the promotion of axonal regeneration is necessary to advance the restoration of function. In the future, refinement of animal models according to clinical conditions and requirements may contribute to greater translational success. PMID:27303641

  20. Tensile Properties of Contractile and Synthetic Vascular Smooth Muscle Cells

    NASA Astrophysics Data System (ADS)

    Miyazaki, Hiroshi; Hasegawa, Yoshitaka; Hayashi, Kozaburo

    Tensile properties of vascular smooth muscle cells (VSMCs) of synthetic and contractile phenotypes were determined using a newly developed tensile test system. Synthetic and contractile VSMCs were isolated from the rabbit thoracic aorta with an explant and an enzymatic digestion method, respectively. Each cell floated in Hanks' balanced salt solution of 37°C was attached to the fine tips of a pair of micropipettes with a cell adhesive and, then, stretched at the rate of 6µm/sec by moving one of the micropipettes with a linear actuator. Load applied to the cell was measured with a cantilever-type load cell; its elongation was determined from the distance between the micropipette tips using a video dimension analyzer. The synthetic and contractile VSMCs were not broken even at the tensile force of 2.4µN and 3.4µN, respectively. Their stiffness was significantly higher in contractile phenotype (0.17N/m) than in synthetic one (0.09N/m). The different tensile properties between synthetic and contractile cells are attributable to the differences in cytoskeletal structures and contractile apparatus.

  1. Diaphragm contractile dysfunction causes by off-target low-dose irradiation

    PubMed Central

    Hsieh, Chen-Hsi; Lin, Yun-Cheng; Chen, Yu-Jen; Wu, Huey-Dong; Wang, Li-Ying

    2016-01-01

    Background: Diaphragm is a primary inspiratory muscle and often receives off-target dose in patients with thoracic radiotherapy, and whether acute effect of low dose irradiation would cause contractile dysfunction of the diaphragm remains unclear. We use a rat model to investigate the effect of low-dose irradiation on diaphragm contractile function in the current study. Methods: The radiation dose distributions in patients with esophageal cancer receiving radiotherapy were calculated to determine the dose received by the off-target diaphragm area. Rats were randomly assigned to an irradiated or a non-irradiated control group (n = 10 per group). A single-fraction of 5 Gy radiation was then delivered to the diaphragms of Sprague-Dawley rats in the irradiated group. The control group received sham irradiation (0 Gy). Rats were sacrificed 24 hours after the irradiation procedures and diaphragms were removed en bloc for contractile function assessment, oxidative injury and DNA damage analysis. Oxidative injury was determined by analyzing concentration of protein carbonyls and DNA damage was determined by analyzing retention of γH2AX foci in nuclei of diaphragmatic tissue. Results: At 24 hours after delivery of a single dose of 5 Gy radiation, specific twitch (p = 0.03) and tetanus tension (p = 0.02) were significantly lower in the irradiated group than in the control group. The relative force-frequency curves showed a significant downward shift in the irradiated group. Protein carbonyl level (p < 0.01) and percentage of γH2AX-positive diaphragm muscle cells were significantly higher in the irradiated group than in the control group 24 hours after irradiation (58% vs. 30%, p = 0.01). Conclusions: Off-target low dose irradiation could induce acute contractile dysfunction of the diaphragm which was related to radiation-induced direct DNA and indirect oxidative damage. PMID:27186277

  2. Improving balance function using vestibular stochastic resonance: optimizing stimulus characteristics.

    PubMed

    Mulavara, Ajitkumar P; Fiedler, Matthew J; Kofman, Igor S; Wood, Scott J; Serrador, Jorge M; Peters, Brian; Cohen, Helen S; Reschke, Millard F; Bloomberg, Jacob J

    2011-04-01

    modality to enhance adaptability or skill acquisition, or as a miniature patch-type stimulator that may be worn by people with disabilities due to aging or disease to improve posture and locomotion function. PMID:21442221

  3. Structure of the Elastin-Contractile Units in the Thoracic Aorta and How Genes That Cause Thoracic Aortic Aneurysms and Dissections Disrupt This Structure.

    PubMed

    Karimi, Ashkan; Milewicz, Dianna M

    2016-01-01

    The medial layer of the aorta confers elasticity and strength to the aortic wall and is composed of alternating layers of smooth muscle cells (SMCs) and elastic fibres. The SMC elastin-contractile unit is a structural unit that links the elastin fibres to the SMCs and is characterized by the following: (1) layers of elastin fibres that are surrounded by microfibrils; (2) microfibrils that bind to the integrin receptors in focal adhesions on the cell surface of the SMCs; and (3) SMC contractile filaments that are linked to the focal adhesions on the inner side of the membrane. The genes that are altered to cause thoracic aortic aneurysms and aortic dissections encode proteins involved in the structure or function of the SMC elastin-contractile unit. Included in this gene list are the genes encoding protein that are structural components of elastin fibres and microfibrils, FBN1, MFAP5, ELN, and FBLN4. Also included are genes that encode structural proteins in the SMC contractile unit, including ACTA2, which encodes SMC-specific α-actin and MYH11, which encodes SMC-specific myosin heavy chain, along with MYLK and PRKG1, which encode kinases that control SMC contraction. Finally, mutations in the gene encoding the protein linking integrin receptors to the contractile filaments, FLNA, also predispose to thoracic aortic disease. Thus, these data suggest that functional SMC elastin-contractile units are important for maintaining the structural integrity of the aorta. PMID:26724508

  4. Splenectomy Improves Hemostatic and Liver Functions in Hepatosplenic Schistosomiasis Mansoni

    PubMed Central

    Leite, Luiz Arthur Calheiros; Pimenta Filho, Adenor Almeida; Ferreira, Rita de Cássia dos Santos; da Fonseca, Caíque Silveira Martins; dos Santos, Bianka Santana; Montenegro, Silvia Maria Lucena; Lopes, Edmundo Pessoa de Almeida; Domingues, Ana Lúcia Coutinho; Owen, James Stuart; Lima, Vera Lucia de Menezes

    2015-01-01

    Background Schistosomiasis mansoni is a chronic liver disease, in which some patients (5–10%) progress to the most severe form, hepatosplenic schistosomiasis. This form is associated with portal hypertension and splenomegaly, and often episodes of gastrointestinal bleeding, even with liver function preserved. Splenectomy is a validated procedure to reduce portal hypertension following digestive bleeding. Here, we evaluate beneficial effects of splenectomy on blood coagulation factors and liver function tests in hepatosplenic schistosomiasis mansoni compared to non-operated patients. Methodology/Principal Findings Forty-five patients who had undergone splenectomy surgery were assessed by laboratory analyses and ultrasound examination and compared to a non-operated group (n = 55). Blood samples were obtained for liver function tests, platelet count and prothrombin time. Coagulation factors (II, VII, VIII, IX and X), protein C and antithrombin IIa, plasminogen activator inhibitor-1 were measured by routine photometric, chromogenic or enzyme-linked immunosorbent assays, while hyperfibrinolysis was defined by plasminogen activator inhibitor-1 levels. Both groups had similar age, gender and pattern of periportal fibrosis. Splenectomized patients showed significant reductions in portal vein diameter, alkaline phosphatase and bilirubin levels compared to non-operated patients, while for coagulation factors there were significant improvement in prothrombin, partial thromboplastin times and higher levels of factor VII, VIII, IX, X, protein C and plasminogen activator inhibitor-1. Conclusion/Significance This study shows that the decrease of flow pressure in portal circulation after splenectomy restores the capacity of hepatocyte synthesis, especially on the factor VII and protein C levels, and these findings suggest that portal hypertension in patients with hepatosplenic schistosomiasis influences liver functioning and the blood coagulation status. PMID:26267788

  5. Relationship between systolic and diastolic function with improvements in forward stroke volume following reduction in mitral regurgitation

    NASA Technical Reports Server (NTRS)

    Firstenberg, M. S.; Greenberg, N. L.; Smedira, N. G.; McCarthy, P. M.; Garcia, M. J.; Thomas, J. D.

    2001-01-01

    Efforts to improve mitral regurgitation (MR) are often performed in conjunction with coronary revascularization. However, the independent effects of a reduced MR area (MRa) are difficult to quantify. Using a previously developed cardiovascular model, ventricular contractility (elastance 1-8 mmHg/ml) and relaxation (tau: 40-150 msec) were independently adjusted for four grades of MR orifice areas (0.0 to 0.8 cm2). Improvements in forward stroke volume (fSV) were determined for the permutations of reduced MRa. For all conditions, LV end-diastolic pressure and volumes ranged from 7.3-24.2 mmHg and 64.8-174.3 ml, respectively. Overall, fSV ranged from 36.0-89.4 (mean: 64.2 +/- 12.8) ml, improved between 6.4 and 35.3% (mean: 15.6 +/- 8.1%), and was best predicted by (r=0.97, p<0.01) %delta(fSV)[correction of fVS]=34[MRa initial] - 46[MRa final] -0.5[elastance]. Reduced MRa, independent of relaxation and minimally influence by contractility, yield improved fSVs.

  6. Improving Project Management with Simulation and Completion Distribution Functions

    NASA Technical Reports Server (NTRS)

    Cates, Grant R.

    2004-01-01

    million per month is being spent on this project, which is scheduled to complete by 2010. NASA project stakeholders participated in determining and managing completion distribution functions produced from PAST. The first result was that project stakeholders improved project completion risk awareness. Secondly, using PAST, mitigation options were analyzed to improve project completion performance and reduce total project cost.

  7. Does Transendocardial Injection of Mesenchymal Stem Cells Improve Myocardial Function Locally or Globally? An Analysis From the POSEIDON Randomized Trial

    PubMed Central

    Suncion, Viky Y.; Ghersin, Eduard; Fishman, Joel E.; Zambrano, Juan Pablo; Karantalis, Vasileios; Mandel, Nicole; Nelson, Katarina H; Gerstenblith, Gary; Velazquez, Darcy L. DiFede; Breton, Elayne; Sitammagari, Kranthi; Schulman, Ivonne H.; N.Taldone, Sabrina; Williams, Adam R.; Sanina, Cristina; Johnston, Peter V.; Brinker, Jeffrey; Altman, Peter; Mushtaq, Muzammil; Trachtenberg, Barry; Mendizabal, Adam M.; Tracy, Melissa; Da Silva, Jose; McNiece, Ian K.; Lardo, Alberto C.; George, Richard T.; Hare, Joshua M.; Heldman, Alan W.

    2014-01-01

    Rationale Transendocardial Stem Cell Injection (TESI) with mesenchymal stem cells improves remodeling in chronic ischemic cardiomyopathy, but the impact of the injection site remains unknown. Objective To address whether TESI exerts its effects at the site of injection only or also in remote areas, we hypothesized that segmental myocardial scar and segmental ejection fraction improve to a greater extent in injected than in non-injected segments. Methods and Results Biplane ventriculographic and endocardial tracings were recorded. TESI was guided to 10 sites in infarct-border zones. Sites were mapped according to the 17-myocardial segment model. As a result, 510 segments were analyzed in 30 patients before and 13-months after TESI. Segmental early enhancement defect (SEED, a measure of scar size) was reduced by TESI in both injected (−43.7±4.4%, n=95, p<0.01) and non-injected segments (−25.1±7.8%, n=148, p<0.001; between group comparison p<0.05). Conversely, segmental ejection fraction (SEF, a measure of contractility) improved in injected scar segments (19.9±3.3 to 26.3±3.5%, p=0.003) but not in non-injected scar segments (21.3±2.6 to 23.5±3.2%, p=0.20, between group comparison p<0.05). In the subgroup of scar segments with baseline SEF<20%, the SEF improvement was even greater in injected segments (12.1±1.2% to 19.9±2.7%, n=18, p=0.003) vs. non-injected segments (13.3±1.3% to 16.1±2.1%, n=15, p=0.05; between group comparison p<0.05). Conclusions These findings illustrate a dichotomy in regional responses to TESI. Although scar reduction was evident at the site of TESI and remotely, ventricular functional responses occurred preferentially at the sites of TESI. Furthermore, improvement was greatest when segmental left ventricular dysfunction was severe. PMID:24449819

  8. Natural Product Discovery through Improved Functional Metagenomics in Streptomyces.

    PubMed

    Iqbal, Hala A; Low-Beinart, Lila; Obiajulu, Joseph U; Brady, Sean F

    2016-08-01

    Because the majority of environmental bacteria are not easily culturable, access to many bacterially encoded secondary metabolites will be dependent on the development of improved functional metagenomic screening methods. In this study, we examined a collection of diverse Streptomyces species for the best innate ability to heterologously express biosynthetic gene clusters. We then optimized methods for constructing high quality metagenomic cosmid libraries in the best Streptomyces host. An initial screen of a 1.5 million-membered metagenomic library constructed in Streptomyces albus, the species that exhibited the highest propensity for heterologous expression of gene clusters, led to the identification of the novel natural product metatricycloene (1). Metatricycloene is a tricyclic polyene encoded by a reductive, iterative polyketide-like gene cluster. Related gene clusters found in sequenced genomes appear to encode a largely unexplored collection of structurally diverse, polyene-based metabolites. PMID:27447056

  9. ATP citrate lyase improves mitochondrial function in skeletal muscle.

    PubMed

    Das, Suman; Morvan, Frederic; Jourde, Benjamin; Meier, Viktor; Kahle, Peter; Brebbia, Pascale; Toussaint, Gauthier; Glass, David J; Fornaro, Mara

    2015-06-01

    Mitochondrial dysfunction is associated with skeletal muscle pathology, including cachexia, sarcopenia, and the muscular dystrophies. ATP citrate lyase (ACL) is a cytosolic enzyme that catalyzes mitochondria-derived citrate into oxaloacetate and acetyl-CoA. Here we report that activation of ACL in skeletal muscle results in improved mitochondrial function. IGF1 induces activation of ACL in an AKT-dependent fashion. This results in an increase in cardiolipin, thus increasing critical mitochondrial complexes and supercomplex activity, and a resultant increase in oxygen consumption and cellular ATP levels. Conversely, knockdown of ACL in myotubes not only reduces mitochondrial complex I, IV, and V activity but also blocks IGF1-induced increases in oxygen consumption. In vivo, ACL activity is associated with increased ATP. Activation of this IGF1/ACL/cardiolipin pathway combines anabolic signaling with induction of mechanisms needed to provide required ATP. PMID:26039450

  10. Hydrogen sulfide improves neural function in rats following cardiopulmonary resuscitation

    PubMed Central

    LIN, JI-YAN; ZHANG, MIN-WEI; WANG, JIN-GAO; LI, HUI; WEI, HONG-YAN; LIU, RONG; DAI, GANG; LIAO, XIAO-XING

    2016-01-01

    The alleviation of brain injury is a key issue following cardiopulmonary resuscitation (CPR). Hydrogen sulfide (H2S) is hypothesized to be involved in the pathophysiological process of ischemia-reperfusion injury, and exerts a protective effect on neurons. The aim of the present study was to investigate the effects of H2S on neural functions following cardiac arrest (CA) in rats. A total of 60 rats were allocated at random into three groups. CA was induced to establish the model and CPR was performed after 6 min. Subsequently, sodium hydrosulfide (NaHS), hydroxylamine or saline was administered to the rats. Serum levels of H2S, neuron-specific enolase (NSE) and S100β were determined following CPR. In addition, neurological deficit scoring (NDS), the beam walking test (BWT), prehensile traction test and Morris water maze experiment were conducted. Neuronal apoptosis rates were detected in the hippocampal region following sacrifice. After CPR, as the H2S levels increased or decreased, the serum NSE and S100β concentrations decreased or increased, respectively (P<0.0w. The NDS results of the NaHS group were improved compared with those of the hydroxylamine group at 24 h after CPR (P<0.05). In the Morris water maze experiment, BWT and prehensile traction test the animals in the NaHS group performed best and rats in the hydroxylamine group performed worst. At day 7, the apoptotic index and the expression of caspase-3 were reduced in the hippocampal CA1 region, while the expression of Bcl-2 increased in the NaHS group; and results of the hydroxylamine group were in contrast. Therefore, the results of the present study indicate that H2S is able to improve neural function in rats following CPR. PMID:26893650

  11. Contractile Force of Human Extraocular Muscle: A Theoretical Analysis.

    PubMed

    Guo, Hongmei; Gao, Zhipeng; Chen, Weiyi

    2016-01-01

    Aim. The length-contractile force relationships of six human extraocular muscles (EOMs) in primary innervations should be determined during eye movement modeling and surgery of clinical EOMs. This study aims to investigate these relationships. Method. The proposal is based on the assumption that six EOMs have similar constitutive relationships, with the eye suspended in the primary position. The constitutive relationships of EOMs are obtained by optimizing from previous experimental data and the theory of mechanical equilibrium using traditional model. Further, simulate the existing experiment of resistance force, and then compare the simulated results with the existing experimental results. Finally, the mechanical constitutive relationships of EOMs are obtained. Results. The results show that the simulated resistance forces from the other four EOMs except for the horizontal recti well agree with previous experimental results. Conclusion. The mechanical constitutive relationships of six EOMs in primary innervations are obtained, and the rationality of the constitutive relationships is verified. Whereafter, the active stress-strain relationships of the six EOMs in the primary innervations are obtained. The research results can improve the eye movement model to predict the surgical amounts of EOMs before EOM surgery more precisely. PMID:27087774

  12. Contractile Force of Human Extraocular Muscle: A Theoretical Analysis

    PubMed Central

    Guo, Hongmei; Gao, Zhipeng; Chen, Weiyi

    2016-01-01

    Aim. The length-contractile force relationships of six human extraocular muscles (EOMs) in primary innervations should be determined during eye movement modeling and surgery of clinical EOMs. This study aims to investigate these relationships. Method. The proposal is based on the assumption that six EOMs have similar constitutive relationships, with the eye suspended in the primary position. The constitutive relationships of EOMs are obtained by optimizing from previous experimental data and the theory of mechanical equilibrium using traditional model. Further, simulate the existing experiment of resistance force, and then compare the simulated results with the existing experimental results. Finally, the mechanical constitutive relationships of EOMs are obtained. Results. The results show that the simulated resistance forces from the other four EOMs except for the horizontal recti well agree with previous experimental results. Conclusion. The mechanical constitutive relationships of six EOMs in primary innervations are obtained, and the rationality of the constitutive relationships is verified. Whereafter, the active stress-strain relationships of the six EOMs in the primary innervations are obtained. The research results can improve the eye movement model to predict the surgical amounts of EOMs before EOM surgery more precisely. PMID:27087774

  13. Exercise improves cardiac autonomic function in obesity and diabetes.

    PubMed

    Voulgari, Christina; Pagoni, Stamatina; Vinik, Aaron; Poirier, Paul

    2013-05-01

    Physical activity is a key element in the prevention and management of obesity and diabetes. Regular physical activity efficiently supports diet-induced weight loss, improves glycemic control, and can prevent or delay type 2 diabetes diagnosis. Furthermore, physical activity positively affects lipid profile, blood pressure, reduces the rate of cardiovascular events and associated mortality, and restores the quality of life in type 2 diabetes. However, recent studies have documented that a high percentage of the cardiovascular benefits of exercise cannot be attributed solely to enhanced cardiovascular risk factor modulation. Obesity in concert with diabetes is characterized by sympathetic overactivity and the progressive loss of cardiac parasympathetic influx. These are manifested via different pathogenetic mechanisms, including hyperinsulinemia, visceral obesity, subclinical inflammation and increased thrombosis. Cardiac autonomic neuropathy is an underestimated risk factor for the increased cardiovascular morbidity and mortality associated with obesity and diabetes. The same is true for the role of physical exercise in the restoration of the heart cardioprotective autonomic modulation in these individuals. This review addresses the interplay of cardiac autonomic function in obesity and diabetes, and focuses on the importance of exercise in improving cardiac autonomic dysfunction. PMID:23084034

  14. Improving 3D Genome Reconstructions Using Orthologous and Functional Constraints

    PubMed Central

    Diament, Alon; Tuller, Tamir

    2015-01-01

    The study of the 3D architecture of chromosomes has been advancing rapidly in recent years. While a number of methods for 3D reconstruction of genomic models based on Hi-C data were proposed, most of the analyses in the field have been performed on different 3D representation forms (such as graphs). Here, we reproduce most of the previous results on the 3D genomic organization of the eukaryote Saccharomyces cerevisiae using analysis of 3D reconstructions. We show that many of these results can be reproduced in sparse reconstructions, generated from a small fraction of the experimental data (5% of the data), and study the properties of such models. Finally, we propose for the first time a novel approach for improving the accuracy of 3D reconstructions by introducing additional predicted physical interactions to the model, based on orthologous interactions in an evolutionary-related organism and based on predicted functional interactions between genes. We demonstrate that this approach indeed leads to the reconstruction of improved models. PMID:26000633

  15. Improving harmonic vibrational frequencies calculations in density functional theory

    NASA Astrophysics Data System (ADS)

    Stratmann, R. Eric; Burant, John C.; Scuseria, Gustavo E.; Frisch, Michael J.

    1997-06-01

    Using a previously introduced weight scheme, microbatching, and grid compression [R. E. Stratmann, G. E. Scuseria and M. J. Frisch, Chem. Phys. Lett. 257, 213 (1996)], we significantly speed up the numerical integration of the exchange-correlation contribution to the Coupled-Perturbed Kohn-Sham equations. In addition, we find that the nature of the integrand is such that it is possible to employ substantially fewer grid points in the quadrature and to use the Gaussian very Fast Multipole Method (GvFMM) with very short multipole expansions for the Coulomb contribution, with negligible loss in accuracy. As a representative example, the computational demand for the exchange-correlation portion of a coronene (C24H12) frequency calculation with a 3-21G basis is reduced by more than one order of magnitude. The overall speed up achieved in this calculation is between a factor of 4 to 6, depending on the specific functional. We also present sample calculations using polarized bases, gradient-corrected functionals, and on even larger systems (C54H18 and C96H24), to illustrate the various effects and improvements that we have accomplished.

  16. Improved Functionality and Curation Support in the ADS

    NASA Astrophysics Data System (ADS)

    Accomazzi, Alberto; Kurtz, Michael J.; Henneken, Edwin A.; Grant, Carolyn S.; Thompson, Donna; Chyla, Roman; Holachek, Alexandra; Sudilovsky, Vladimir; Murray, Stephen S.

    2015-01-01

    In this poster we describe the developments of the new ADS platform over the past year, focusing on the functionality which improves its discovery and curation capabilities.The ADS Application Programming Interface (API) is being updated to support authenticated access to the entire suite of ADS services, in addition to the search functionality itself. This allows programmatic access to resources which are specific to a user or class of users.A new interface, built directly on top of the API, now provides a more intuitive search experience and takes into account the best practices in web usability and responsive design. The interface now incorporates in-line views of graphics from the AAS Astroexplorer and the ADS All-Sky Survey image collections.The ADS Private Libraries, first introduced over 10 years ago, are now being enhanced to allow the bookmarking, tagging and annotation of records of interest. In addition, libraries can be shared with one or more ADS users, providing an easy way to collaborate in the curation of lists of papers. A library can also be explicitly made public and shared at large via the publishing of its URL.In collaboration with the AAS, the ADS plans to support the adoption of ORCID identifiers by implementing a plugin which will simplify the import of papers in ORCID via a query to the ADS API. Deeper integration between the two systems will depend on available resources and feedback from the community.

  17. NADPH oxidase-2 inhibition restores contractility and intracellular calcium handling and reduces arrhythmogenicity in dystrophic cardiomyopathy

    PubMed Central

    Gonzalez, Daniel R.; Treuer, Adriana V.; Lamirault, Guillaume; Mayo, Vera; Cao, Yenong; Dulce, Raul A.

    2014-01-01

    Duchenne muscular dystrophy may affect cardiac muscle, producing a dystrophic cardiomyopathy in humans and the mdx mouse. We tested the hypothesis that oxidative stress participates in disrupting calcium handling and contractility in the mdx mouse with established cardiomyopathy. We found increased expression (fivefold) of the NADPH oxidase (NOX) 2 in the mdx hearts compared with wild type, along with increased superoxide production. Next, we tested the impact of NOX2 inhibition on contractility and calcium handling in isolated cardiomyocytes. Contractility was decreased in mdx myocytes compared with wild type, and this was restored toward normal by pretreating with apocynin. In addition, the amplitude of evoked intracellular Ca2+ concentration transients that was diminished in mdx myocytes was also restored with NOX2 inhibition. Total sarcoplasmic reticulum (SR) Ca2+ content was reduced in mdx hearts and normalized by apocynin treatment. Additionally, NOX2 inhibition decreased the production of spontaneous diastolic calcium release events and decreased the SR calcium leak in mdx myocytes. In addition, nitric oxide (NO) synthase 1 (NOS-1) expression was increased eightfold in mdx hearts compared with wild type. Nevertheless, cardiac NO production was reduced. To test whether this paradox implied NOS-1 uncoupling, we treated cardiac myocytes with exogenous tetrahydrobioterin, along with the NOX inhibitor VAS2870. These agents restored NO production and phospholamban phosphorylation in mdx toward normal. Together, these results demonstrate that, in mdx hearts, NOX2 inhibition improves the SR calcium handling and contractility, partially by recoupling NOS-1. These findings reveal a new layer of nitroso-redox imbalance in dystrophic cardiomyopathy. PMID:25015966

  18. Activation of volume-sensitive outwardly rectifying chloride channel by ROS contributes to ER stress and cardiac contractile dysfunction: involvement of CHOP through Wnt.

    PubMed

    Shen, M; Wang, L; Wang, B; Wang, T; Yang, G; Shen, L; Wang, T; Guo, X; Liu, Y; Xia, Y; Jia, L; Wang, X

    2014-01-01

    Endoplasmic reticulum (ER) stress occurring in stringent conditions is critically involved in cardiomyocytes apoptosis and cardiac contractile dysfunction (CCD). However, the molecular machinery that mediates cardiac ER stress and subsequent cell death remains to be fully deciphered, which will hopefully provide novel therapeutic targets for these disorders. Here, we establish tunicamycin-induced model of cardiomyocyte ER stress, which effectively mimicks pathological stimuli to trigger CCD. Tunicamycin activates volume-sensitive outward rectifying Cl(-) currents. Blockade of the volume-sensitive outwardly rectifying (VSOR) Cl(-) channel by 4,4'-diisothiocya-natostilbene-2,2'-disulfonic acid (DIDS), a non-selective Cl(-) channel blocker, and 4-(2-butyl-6,7-dichlor-2-cyclopentyl-indan-1-on-5-yl) oxybutyric acid (DCPIB), a selective VSOR Cl(-) channel blocker, improves cardiac contractility, which correlates with suppressed ER stress through inhibiting the canonical GRP78/eIF2α/ATF4 and XBP1 pathways, and promotes survival of cardiomyocytes by inverting tunicamycin-induced decrease of Wnt through the CHOP pathway. VSOR activation of tunicamycin-treated cardiomyocytes is attributed to increased intracellular levels of reactive oxygen species (ROS). Our study demonstrates a pivotal role of ROS/VSOR in mediating ER stress and functional impairment of cardiomyocytes via the CHOP-Wnt pathway, and suggests the therapeutic values of VSOR Cl(-) channel blockers against ER stress-associated cardiac anomalies. PMID:25412307

  19. Activation of volume-sensitive outwardly rectifying chloride channel by ROS contributes to ER stress and cardiac contractile dysfunction: involvement of CHOP through Wnt

    PubMed Central

    Shen, M; Wang, L; Wang, B; Wang, T; Yang, G; Shen, L; Wang, T; Guo, X; Liu, Y; Xia, Y; Jia, L; Wang, X

    2014-01-01

    Endoplasmic reticulum (ER) stress occurring in stringent conditions is critically involved in cardiomyocytes apoptosis and cardiac contractile dysfunction (CCD). However, the molecular machinery that mediates cardiac ER stress and subsequent cell death remains to be fully deciphered, which will hopefully provide novel therapeutic targets for these disorders. Here, we establish tunicamycin-induced model of cardiomyocyte ER stress, which effectively mimicks pathological stimuli to trigger CCD. Tunicamycin activates volume-sensitive outward rectifying Cl− currents. Blockade of the volume-sensitive outwardly rectifying (VSOR) Cl− channel by 4,4'-diisothiocya-natostilbene-2,2'-disulfonic acid (DIDS), a non-selective Cl− channel blocker, and 4-(2-butyl-6,7-dichlor-2-cyclopentyl-indan-1-on-5-yl) oxybutyric acid (DCPIB), a selective VSOR Cl− channel blocker, improves cardiac contractility, which correlates with suppressed ER stress through inhibiting the canonical GRP78/eIF2α/ATF4 and XBP1 pathways, and promotes survival of cardiomyocytes by inverting tunicamycin-induced decrease of Wnt through the CHOP pathway. VSOR activation of tunicamycin-treated cardiomyocytes is attributed to increased intracellular levels of reactive oxygen species (ROS). Our study demonstrates a pivotal role of ROS/VSOR in mediating ER stress and functional impairment of cardiomyocytes via the CHOP-Wnt pathway, and suggests the therapeutic values of VSOR Cl− channel blockers against ER stress-associated cardiac anomalies. PMID:25412307

  20. Ascribing Functions to Genes: Journey Towards Genetic Improvement of Rice Via Functional Genomics.

    PubMed

    Mustafiz, Ananda; Kumari, Sumita; Karan, Ratna

    2016-06-01

    Rice, one of the most important cereal crops for mankind, feeds more than half the world population. Rice has been heralded as a model cereal owing to its small genome size, amenability to easy transformation, high synteny to other cereal crops and availability of complete genome sequence. Moreover, sequence wealth in rice is getting more refined and precise due to resequencing efforts. This humungous resource of sequence data has confronted research fraternity with a herculean challenge as well as an excellent opportunity to functionally validate expressed as well as regulatory portions of the genome. This will not only help us in understanding the genetic basis of plant architecture and physiology but would also steer us towards developing improved cultivars. No single technique can achieve such a mammoth task. Functional genomics through its diverse tools viz. loss and gain of function mutants, multifarious omics strategies like transcriptomics, proteomics, metabolomics and phenomics provide us with the necessary handle. A paradigm shift in technological advances in functional genomics strategies has been instrumental in generating considerable amount of information w.r.t functionality of rice genome. We now have several databases and online resources for functionally validated genes but despite that we are far from reaching the desired milestone of functionally characterizing each and every rice gene. There is an urgent need for a common platform, for information already available in rice, and collaborative efforts between researchers in a concerted manner as well as healthy public-private partnership, for genetic improvement of rice crop better able to handle the pressures of climate change and exponentially increasing population. PMID:27252584

  1. Thin filament incorporation of an engineered cardiac troponin C variant (L48Q) enhances contractility in intact cardiomyocytes from healthy and infarcted hearts

    PubMed Central

    Feest, Erik R.; Korte, F. Steven; Tu, An-yue; Dai, Jin; Razumova, Maria V.; Murry, Charles E.; Regnier, Michael

    2014-01-01

    Many current pharmaceutical therapies for systolic heart failure target intracellular [Ca2+] ([Ca2+]i) metabolism, or cardiac troponin C (cTnC) on thin filaments, and can have significant side-effects, including arrhythmias or adverse effects on diastolic function. In this study, we tested the feasibility of directly increasing the Ca2+ binding properties of cTnC to enhance contraction independent of [Ca2+]i in intact cardiomyocytes from healthy and myocardial infarcted (MI) hearts. Specifically, cardiac thin filament activation was enhanced through adenovirus-mediated over-expression of a cardiac troponin C (cTnC) variant designed to have increased Ca2+ binding affinity conferred by single amino acid substitution (L48Q). In skinned cardiac trabeculae and myofibrils we and others have shown that substitution of L48Q cTnC for native cTnC increases Ca2+ sensitivity of force and the maximal rate of force development. Here we introduced L48Q cTnC into myofilaments of intact cardiomyocytes via adeno-viral transduction to deliver cDNA for the mutant or wild type (WT) cTnC protein. Using video-microscopy to monitor cell contraction, relaxation, and intracellular Ca2+ transients (Fura-2), we report that incorporation of L48Q cTnC significantly increased contractility of cardiomyocytes from healthy and MI hearts without adversely affecting Ca2+ transient properties or relaxation. The improvements in contractility from L48Q cTnC expression are likely the result of enhanced contractile efficiency, as intracellular Ca2+ transient amplitudes were not affected. Expression and incorporation of L48Q cTnC into myofilaments was confirmed by Western blot analysis of myofibrils from transduced cardiomyocytes, which indicated replacement of 18±2% of native cTnC with L48Q cTnC. These experiments demonstrate the feasibility of directly targeting cardiac thin filament proteins to enhance cardiomyocyte contractility that is impaired following MI. PMID:24690333

  2. Aging changes agonist induced contractile responses in permeabilized rat bladder.

    PubMed

    Durlu-Kandilci, N Tugba; Denizalti, Merve; Sahin-Erdemli, Inci

    2015-08-01

    Aging alters bladder functions where a decrease in filling, storage and emptying is observed. These changes cause urinary incontinence, especially in women. The aim of this study is to examine how aging affects the intracellular calcium movements due to agonist-induced contractions in permeabilized female rat bladder. Urinary bladder isolated from young and old female Sprague-Dawley rats were used. Small detrusor strips were permeabilized with β-escin. The contractile responses induced with agonists were compared between young and old groups. Carbachol-induced contractions were decreased in permeabilized detrusor from old rats compared to young group. Heparin and ryanodine decreased carbachol-induced contractions in young rats where only heparin inhibited these contractions in olds. Caffeine-induced contractions but not inositol triphosphate (IP3)-induced contractions were decreased in old group compared to youngs. The cumulative calcium response curves (pCa 8-4) were also decreased in old rats. Carbachol-induced calcium sensitization responses did not alter by age where GTP-β-S and GF-109203X but not Y-27632 inhibited these responses. Carbachol-induced contractions decrease with aging in rat bladder detrusor. It can be postulated as IP3-induced calcium release (IICR) is primarily responsible for the contractions in older rats where the decrease in carbachol contractions in aging may be as a result of a decrease in calcium-induced calcium release (CICR), rather than carbachol-induced calcium sensitization. PMID:26153091

  3. The actions of neurotensin in rat bladder detrusor contractility

    PubMed Central

    Dong, Xingyou; Bai, Xinyu; Zhao, Jiang; Wang, Liang; Wang, Qingqing; Li, Longkun

    2015-01-01

    This study assessed the expression, distribution and function of neurotensin (NTs) and two main neurotensin receptors (NTSR), NTSR1 and NTSR2 in normal rat urinary bladders. NTs is primarily located in the suburothelium and the interstitium of smooth muscle bundles. The NTSR1 and NTSR2 receptor subtypes are found to co-localize with smooth muscle cells (SMCs). NTs not only can directly act on bladder SMCs to induce intracellular calcium mobilization by activating the phospholipase C/inositol triphosphate (PLC/IP3) pathway, promoting extracellular calcium influx through a non-selective cation channels, but may be also involved in the modulation of the cholinergic system. Nowadays, the selective antimuscarinic drugs (solifenacin) and the selective beta 3-adrenergic agonist (mirabegron) are used as the first-line pharmacotherapy for overactive bladder (OAB), but without satisfactory treatment benefits in some patients. This study provided evidence suggesting that bladder NTs may play an important role in the regulation of micturition. Further research is needed to investigate the effects of NTs on bladder contractility and the underlying mechanism, which might reveal that the administration of NTSR antagonists can potentially relieve the symptoms of OAB by coordination with antimuscarinic pharmacotherapy. PMID:26053252

  4. Effect of trimebutine on contractile responses in skinned ileal smooth muscle.

    PubMed

    Nagasaki, M; Itagaki, M; Komori, S; Ohashi, H

    1994-07-01

    The effects of trimebutine on Ca2+ release and modulation of Ca2+ sensitivity of contractile elements induced by carbachol (CCh) were investigated using a tension measuring method in beta-escin-treated skinned smooth muscle of the longitudinal muscle layer of guinea pig ileum. Trimebutine (10-100 microM) concentration-dependently inhibited tension development brought about by Ca2+ release from intracellular stores induced by CCh (10 microM), but did not affect those induced by inositol 1,4,5-trisphosphate (IP3, 25 microM) or caffeine (5 mM). The inhibitory effect was reversible. Trimebutine (100 microM) neither altered the Ca2+ sensitivity of the contractile elements nor affected the effects of GTP gamma S (50 microM) and CCh (100 microM) in potentiating Ca2+ sensitivity of the contractile elements after the Ca2+ storage function had been eliminated by A23187. These results suggest that trimebutine inhibits CCh-induced Ca2+ release by acting at some point during the coupling of muscarinic receptors through a G-protein to phospholipase C and thus reducing the accumulation of IP3. PMID:7799525

  5. Paxillin and Focal Adhesion Kinase (FAK) Regulate Cardiac Contractility in the Zebrafish Heart

    PubMed Central

    Hirth, Sofia; Bühler, Anja; Bührdel, John B.; Rudeck, Steven; Dahme, Tillman; Rottbauer, Wolfgang; Just, Steffen

    2016-01-01

    An orchestrated interplay of adaptor and signaling proteins at mechano-sensitive sites is essential to maintain cardiac contractility and when defective leads to heart failure. We recently showed that Integrin-linked Kinase (ILK), ß-Parvin and PINCH form the IPP-complex to grant tuned Protein Kinase B (PKB) signaling in the heart. Loss of one of the IPP-complex components results in destabilization of the whole complex, defective PKB signaling and finally heart failure. Two components of IPP, ILK and ß-Parvin directly bind to Paxillin; however, the impact of this direct interaction on the maintenance of heart function is not known yet. Here, we show that targeted gene inactivation of Paxillin results in progressive decrease of cardiac contractility and heart failure in zebrafish without affecting IPP-complex stability and PKB phosphorylation. However, we found that Paxillin deficiency leads to the destabilization of its known binding partner Focal Adhesion Kinase (FAK) and vice versa resulting in degradation of Vinculin and thereby heart failure. Our findings highlight an essential role of Paxillin and FAK in controlling cardiac contractility via the recruitment of Vinculin to mechano-sensitive sites in cardiomyocytes. PMID:26954676

  6. PTP1B triggers integrin-mediated repression of myosin activity and modulates cell contractility

    PubMed Central

    González Wusener, Ana E.; González, Ángela; Nakamura, Fumihiko; Arregui, Carlos O.

    2016-01-01

    ABSTRACT Cell contractility and migration by integrins depends on precise regulation of protein tyrosine kinase and Rho-family GTPase activities in specific spatiotemporal patterns. Here we show that protein tyrosine phosphatase PTP1B cooperates with β3 integrin to activate the Src/FAK signalling pathway which represses RhoA-myosin-dependent contractility. Using PTP1B null (KO) cells and PTP1B reconstituted (WT) cells, we determined that some early steps following cell adhesion to fibronectin and vitronectin occurred robustly in WT cells, including aggregation of β3 integrins and adaptor proteins, and activation of Src/FAK-dependent signalling at small puncta in a lamellipodium. However, these events were significantly impaired in KO cells. We established that cytoskeletal strain and cell contractility was highly enhanced at the periphery of KO cells compared to WT cells. Inhibition of the Src/FAK signalling pathway or expression of constitutive active RhoA in WT cells induced a KO cell phenotype. Conversely, expression of constitutive active Src or myosin inhibition in KO cells restored the WT phenotype. We propose that this novel function of PTP1B stimulates permissive conditions for adhesion and lamellipodium assembly at the protruding edge during cell spreading and migration. PMID:26700725

  7. Oxytocin plus antibiotics: A synergism of potentiation to enhance bovine uterine contractility.

    PubMed

    Piccinno, M; Rizzo, A; Cariello, G; Staffieri, F; Sciorsci, R L

    2016-09-15

    This in vitro study investigates the modulatory effect of three antibiotics (amoxicillin, enrofloxacin, and rifaximin) on contractility of the bovine uterine tissue, in follicular and luteal phases. The evaluation of the effects of these antibiotics (10(-4) M) was performed on oxytocin-induced contractility. The decision to test these antibiotics with the oxytocin (10(-6) M) comes from the reported ability of these combinations of hinder the antibiotic resistance and the formation of bacterial biofilms. The procedures were carried out in isolated organ bath, and the contractile functionality of the strip throughout the experiment was evaluated after a dose of carbachol (10(-5) M). The results demonstrate the different modulatory activity of these antibiotics, on the plateau of contraction induced by oxytocin, in both phases of the estrus cycle. The differing individual antibiotic effects of our testing made it possible to identify, only in some cases. Rifaximin in the follicular phase and enrofloxacin in both phases of the estrous cycle, induced a synergistic enhancement (potentiation) of uterine strip contraction induced by oxytocin. This result is thought important because these associations might enable, in vivo, a simultaneous increase of uterine cleaning and the antimicrobial action on bacteria in planktonic form and of those organized in biofilms. PMID:27173953

  8. The effects of Ginseng Java root extract on uterine contractility in nonpregnant rats

    PubMed Central

    Sukwan, Catthareeya; Wray, Susan; Kupittayanant, Sajeera

    2014-01-01

    Abstract Ginseng Java or Talinum paniculatum (Jacq.) Geartn has long been used in herbal recipes because of its various therapeutic properties. Ginseng Java is believed to be beneficial to the female reproductive system by inducing lactation and restoring uterine functions after the postpartum period. There are, however, no scientific data on verifying the effects on the uterus to support its therapeutic relevance. Therefore, the purpose of this study was to investigate the effects of Ginseng Java root extract and its possible mechanism(s) of action on uterine contractility. Female virgin rats were humanely killed by CO2 asphyxia and uteri removed. Isometric force was measured in strips of longitudinal myometrium. The effects of Ginseng Java root extract at its IC50 concentration (0.23 mg/mL) on spontaneous, oxytocin‐induced (10 nmol/L), and depolarized (KCl 40 mmol/L) contraction were investigated. After establishing regular phasic contractions, the application of Java root extract significantly inhibited spontaneous uterine contractility (n =5). The extract also significantly inhibited the contraction induced by high KCl solution (n =5) and oxytocin (n =5). The extract also inhibited oxytocin‐induced contraction in the absence of external Ca entry (n =7) and the tonic force induced by oxytocin in the presence of high KCl solution. Taken together, the data demonstrate a potent and consistent ability of extract from Ginseng Java root to reduce myometrial contractility. The tocolytic effects were demonstrated on both spontaneous and agonist‐induced contractions. The fact that force was inhibited in depolarized conditions suggests that the possible mechanisms may be blockade of Ca influx via L‐type Ca channels. The data in Ca‐free solutions suggest that the extract also reduces IP3‐induced Ca release from the internal store. These tocolytic effects do not support the use of ginseng to help with postpartum contractility, but instead suggest it may be

  9. Human cerebrovascular contractile receptors are upregulated via a B-Raf/MEK/ERK-sensitive signaling pathway

    PubMed Central

    2011-01-01

    Background Cerebral ischemia results in a rapid increase in contractile cerebrovascular receptors, such as the 5-hydroxytryptamine type 1B (5-HT1B), angiotensin II type 1 (AT1), and endothelin type B (ETB) receptors, in the vessel walls within the ischemic region, which further impairs local blood flow and aggravates tissue damage. This receptor upregulation occurs via activation of the mitogen-activated protein kinase pathway. We therefore hypothesized an important role for B-Raf, the first signaling molecule in the pathway. To test our hypothesis, human cerebral arteries were incubated at 37°C for 48 h in the absence or presence of a B-Raf inhibitor: SB-386023 or SB-590885. Contractile properties were evaluated in a myograph and protein expression of the individual receptors and activated phosphorylated B-Raf (p-B-Raf) was evaluated immunohistochemically. Results 5-HT1B, AT1, and ETB receptor-mediated contractions were significantly reduced by application of SB-590885, and to a smaller extent by SB-386023. A marked reduction in AT1 receptor immunoreactivity was observed after treatment with SB-590885. Treatment with SB-590885 and SB-386023 diminished the culture-induced increase of p-B-Raf immunoreactivity. Conclusions B-Raf signaling has a key function in the altered expression of vascular contractile receptors observed after organ culture. Therefore, specific targeting of B-Raf might be a novel approach to reduce tissue damage after cerebral ischemia by preventing the previously observed upregulation of contractile receptors in smooth muscle cells. PMID:21223556

  10. Does Functional Outcome Improve with Time Postsurgery for Hirschsprung Disease?

    PubMed

    Aworanti, Olugbenga Michael; McDowell, Dermot Thomas; Martin, Ian Michael; Quinn, Feargal

    2016-04-01

    Purpose Constipation and incontinence are significant problems following pull-through surgery for Hirschsprung disease (HD). There is evidence that these problems improve with time. However, there is also evidence showing no improvements and furthermore, significant long-term data are lacking for the newer endorectal pull-through. We aim to determine if there is clinical evidence that show improvements in functional outcomes with time after an endorectal pull-through surgery for HD. Methods We utilized the validated pediatric incontinence and constipation scoring system (PICSS) to score 51 consecutive children 3 months to 15 years posttransabdominal or transanal endorectal pull-through for HD. Cases of total colonic aganglionosis and Down syndrome were excluded. PICSS scores below the age-specific lower limit 95% confidence interval scores represent incomplete continence or constipation, respectively. We performed linear regression to analyze the relationship between PICSS scores and the follow-up duration and then compared the demographics of children with and without incomplete continence and constipation, respectively. Significance was set at p < 0.05. Results The median age at PICSS interview was 71 months (range, 6-191 months). Incontinence scores obtained from 42 children older than 35 months showed a positive relationship with the follow-up duration (p = 0.03). Constipation scores obtained from 51 children were unrelated to follow-up duration (p = 0.486). When demographics were compared, the continent children had longer follow-up than those with incomplete continence (mean, 111.64 vs. 69.19 months; p = 0.051), however follow-up duration did not differ in the group of constipated children compared with the nonconstipated group (mean, 61.88 vs. 71.80 months; p = 0.321). Conclusion These findings suggest that after an endorectal pull-through, improved continence should be expected with time but constipation often continues to be an

  11. Impact of septal flash and left ventricle contractile reserve on positive remodeling during 1 year cardiac resynchronization therapy: the multicenter ViaCRT study

    PubMed Central

    Gąsior, Zbigniew; Płońska-Gościniak, Edyta; Wita, Krystian; Mizia-Stec, Katarzyna; Szwed, Hanna; Kasprzak, Jarosław; Tomaszewski, Andrzej; Sinkiewicz, Władysław; Wojciechowska, Celina

    2016-01-01

    Introduction Cardiac resynchronization therapy (CRT) has been shown to improve outcomes in patients with systolic heart failure (HFREF). However, the relatively high non-responder rate results in a need for more precise qualification for CRT. The ViaCRT study was designed to determine the role of contractile reserve and dyssynchrony parameters in predicting CRT response. The purpose of this analysis was to determine the effect of baseline septal flash and contractile reserve (CR) on clinical and echocardiographic parameters of response to CRT in 12-month follow-up. Material and methods One hundred thirty-three guideline-selected CRT candidates (both ischemic and non-ischemic heart failure with reduced ejection fraction) were enrolled in the study. Baseline study population characteristics were: left ventricle ejection fraction (LVEF) 25 ±6%, QRS 165 ±25 ms, NYHA class III (90%) and IV (10%). Results In subjects with septal flash (SF) registered before CRT implantation improvement in LVEF (14 ±2% vs. 8 ±1%, p < 0.05) and left ventricle (LV) systolic (63 ±10 ml vs. 36 ±6 ml, p < 0.05) and diastolic (46 ±10 ml vs. 32 ±7, p < 0.05) volumes was more pronounced than in patients without SF. In patients with CR (defined as LVEF increase by 20% or 4 viable segments) improvement in echo parameters was not significantly different then in the CR– group. Neither SF nor CR was associated with improvement in NYHA class. Subgroup analysis revealed that only in non-ischemic HF patients is presence of septal flash associated with LV function improvement after CRT. Conclusions In non-ischemic HF patients septal flash is a helpful parameter in prediction of LV remodeling after 12 months of resynchronization therapy. PMID:27186179

  12. Purinergic and cholinergic components of bladder contractility and flow.

    PubMed

    Theobald, R J

    1995-01-01

    The role of ATP as a neurotransmitter/neuromodulator in the urinary tract has been the subject of much study, particularly whether ATP has a functional role in producing urine flow. Recent studies suggested significant species variation, specifically a variation between cat and other species. This study was performed to determine the in vivo response of cat urinary bladder to pelvic nerve stimulation (PNS) and to the exogenous administration of cholinergic and purinergic agents. In anesthetized cats, bladder contractions and fluid expulsion was measured in response to PNS and to the exogenous administration of cholinergic and purinergic agents. Fluid was instilled into the bladder and any fluid expelled by bladder contractions induced by PNS or exogenous agents was collected in a beaker. The volume was measured in a graduated cylinder and recorded. PNS, carbachol and APPCP produced sustained contractions with significant expulsion of fluid. ATP, ACh and hypogastric nerve stimulation did not produce any significant expulsion of fluid. Atropine, a cholinergic antagonist, inhibited PNS contractions and fluid expulsion with no effect on purinergic actions. There was a significant relationship between the magnitude of the contraction, duration of the contractions and volume of fluid expelled. The data and information from other studies, strongly suggests a functional role for ATP as a cotransmitter in the lower urinary tract different from ACh's role. ATP stimulation of a specific purinergic receptor plays a role in initiation of bladder contractions and perhaps in the initiation of urine flow from the bladder. ACh's role is functionally different and appears to be more involved in maintenance of contractile activity and flow. PMID:7830505

  13. Aldehyde dehydrogenase 2 activation in heart failure restores mitochondrial function and improves ventricular function and remodelling

    PubMed Central

    Gomes, Katia M.S.; Campos, Juliane C.; Bechara, Luiz R.G.; Queliconi, Bruno; Lima, Vanessa M.; Disatnik, Marie-Helene; Magno, Paulo; Chen, Che-Hong; Brum, Patricia C.; Kowaltowski, Alicia J.; Mochly-Rosen, Daria; Ferreira, Julio C.B.

    2014-01-01

    Aims We previously demonstrated that pharmacological activation of mitochondrial aldehyde dehydrogenase 2 (ALDH2) protects the heart against acute ischaemia/reperfusion injury. Here, we determined the benefits of chronic activation of ALDH2 on the progression of heart failure (HF) using a post-myocardial infarction model. Methods and results We showed that a 6-week treatment of myocardial infarction-induced HF rats with a selective ALDH2 activator (Alda-1), starting 4 weeks after myocardial infarction at a time when ventricular remodelling and cardiac dysfunction were present, improved cardiomyocyte shortening, cardiac function, left ventricular compliance and diastolic function under basal conditions, and after isoproterenol stimulation. Importantly, sustained Alda-1 treatment showed no toxicity and promoted a cardiac anti-remodelling effect by suppressing myocardial hypertrophy and fibrosis. Moreover, accumulation of 4-hydroxynonenal (4-HNE)-protein adducts and protein carbonyls seen in HF was not observed in Alda-1-treated rats, suggesting that increasing the activity of ALDH2 contributes to the reduction of aldehydic load in failing hearts. ALDH2 activation was associated with improved mitochondrial function, including elevated mitochondrial respiratory control ratios and reduced H2O2 release. Importantly, selective ALDH2 activation decreased mitochondrial Ca2+-induced permeability transition and cytochrome c release in failing hearts. Further supporting a mitochondrial mechanism for ALDH2, Alda-1 treatment preserved mitochondrial function upon in vitro aldehydic load. Conclusions Selective activation of mitochondrial ALDH2 is sufficient to improve the HF outcome by reducing the toxic effects of aldehydic overload on mitochondrial bioenergetics and reactive oxygen species generation, suggesting that ALDH2 activators, such as Alda-1, have a potential therapeutic value for treating HF patients. PMID:24817685

  14. Developing crash modification functions for pedestrian signal improvement.

    PubMed

    Sacchi, Emanuele; Sayed, Tarek; Osama, Ahmed

    2015-10-01

    Pedestrian signals are viable traffic control devices that help pedestrians to cross safely at intersections. Although the literature is extensive when dealing with pedestrian signals design and operations, few studies have focused on the potential safety benefits of installing pedestrian signals at intersections. Most of these studies employed simple before-after (BA) safety evaluation techniques which suffer from methodological and statistical issues. Recent advances in safety evaluation research advocate the use of crash modification functions (CMFunctions) to represent the safety effectiveness of treatments. Unlike crash modification factors (CMFs) that are represented as single values, CMFunctions account for variable treatment location characteristics (heterogeneity). Therefore, the main objective of this study was to quantify the safety impact of installing pedestrian signals at signalized intersections by developing CMFunctions within an observational BA study. The use of observational BA framework to develop the CMFunctions avoids the cross-sectional approach where the functions are derived based on a single time period and no actual treatment intervention. Treatment sites heterogeneity was incorporated into CMFunctions using fixed-effects and random-effects regression models. In addition to heterogeneity, the paper also advocates the use of CMFunctions with a time variable to acknowledge that the safety treatment (intervention) effects do not occur instantaneously but are spread over future time. This is achieved using non-linear intervention (Koyck) models, developed within a hierarchical full Bayes context. The results demonstrated the importance of considering treatment sites heterogeneity (i.e., different circulating volumes and area type among treated locations) and time trends when developing CMFunctions for pedestrian signal improvement. PMID:26196466

  15. Voluntary exercise improves hypothalamic and metabolic function in obese mice.

    PubMed

    Laing, Brenton T; Do, Khoa; Matsubara, Tomoko; Wert, David W; Avery, Michael J; Langdon, Erin M; Zheng, Donghai; Huang, Hu

    2016-05-01

    Exercise plays a critical role in regulating glucose homeostasis and body weight. However, the mechanism of exercise on metabolic functions associated with the CNS has not been fully understood. C57BL6 male mice (n=45) were divided into three groups: normal chow diet, high-fat diet (HFD) treatment, and HFD along with voluntary running wheel exercise training for 12 weeks. Metabolic function was examined by the Comprehensive Lab Animal Monitoring System and magnetic resonance imaging; phenotypic analysis included measurements of body weight, food intake, glucose and insulin tolerance tests, as well as insulin and leptin sensitivity studies. By immunohistochemistry, the amount changes in the phosphorylation of signal transducer and activator of transcription 3, neuronal proliferative maker Ki67, apoptosis positive cells as well as pro-opiomelanocortin (POMC)-expressing neurons in the arcuate area of the hypothalamus was identified. We found that 12 weeks of voluntary exercise training partially reduced body weight gain and adiposity induced by an HFD. Insulin and leptin sensitivity were enhanced in the exercise training group verses the HFD group. Furthermore, the HFD-impaired POMC-expressing neuron is remarkably restored in the exercise training group. The restoration of POMC neuron number may be due to neuroprotective effects of exercise on POMC neurons, as evidenced by altered proliferation and apoptosis. In conclusion, our data suggest that voluntary exercise training improves metabolic symptoms induced by HFD, in part through protected POMC-expressing neuron from HFD and enhanced leptin signaling in the hypothalamus that regulates whole-body energy homeostasis. PMID:26931136

  16. Effects of Hindlimb Unweighting on Arterial Contractile Responses in Mice

    NASA Technical Reports Server (NTRS)

    Ma, Jia; Ren, Xin-Ling; Purdy, Ralph E.

    2003-01-01

    The aim of this work was to determine if hindlimb unweighting in mice alters arterial contractile responses. Sixteen male C57B/6 mice and 16 male Chinese Kunming mice were divided into control and 3 weeks hindlimb unweighting groups, respectively. Using isolated arterial rings from different arteries of mouse, effects of 3 weeks hindlimb unweighting on arterial contractile responsiveness were examined in vitro. The results showed that, in arterial rings from both C57B/6 and Chinese Kunming mice, maximum isometric contractile tensions evoked by either KCl or phenylephrine were significantly lower in abdominal aortic, mesenteric arterial and femoral arterial rings from hindlimb unweighting, compared to control mice. However, the maximal contractile responses of common carotid rings to KCl and PE were not significantly different between control and hindlimb unweighting groups. The sensitivity (EC(sub 50)) of all arteries to KCl or PE showed no significant differences between control and hindlimb unweighting mice. These data indicated that 3 weeks hindlimb unweighting results in a reduced capacity of the arterial smooth muscle of the hindquarter to develop tension. In addition, the alterations in arterial contractile responses caused by hindlimb unweighting in mice are similar as those in rats. Our work suggested that hindlimb unweighting mouse model may be used as a model for the study of postflight cardiovascular deconditioning.

  17. Effect of gender on rat upper airway muscle contractile properties.

    PubMed

    Cantillon, D; Bradford, A

    1998-08-01

    Obstructive sleep apnoea arises due to upper airway (UA) collapse which is normally counteracted by contraction of UA muscles such as the sternohyoids and geniohyoids. The disorder has a marked male predominance but the effect of gender on UA muscle contractile properties is unknown and these properties have not been compared for the sternohyoid and geniohyoid muscles in the same species. Isometric contractile characteristics were determined using strips of sternohyoid and geniohyoid muscle from male and female rats in Krebs solution at 30 degrees C. For both muscles, there were no differences between male and female contractile kinetics, twitch or tetanic tension, tension-length or tension-frequency relationship or endurance. In both males and females, sternohyoid twitch and tetanic tension was greater than geniohyoid. Sternohyoid endurance was less than geniohyoid but contractile kinetics, tension-length and tension-frequency relationships were similar. Therefore, gender does not affect UA muscle contractile properties and sternohyoid tension is greater and endurance less than that of the geniohyoid. PMID:9832233

  18. Changes of smooth muscle contractile filaments in small bowel atresia

    PubMed Central

    Gfroerer, Stefan; Fiegel, Henning; Ramachandran, Priya; Rolle, Udo; Metzger, Roman

    2012-01-01

    AIM: To investigate morphological changes of intestinal smooth muscle contractile fibres in small bowel atresia patients. METHODS: Resected small bowel specimens from small bowel atresia patients (n = 12) were divided into three sections (proximal, atretic and distal). Standard histology hematoxylin-eosin staining and enzyme immunohistochemistry was performed to visualize smooth muscle contractile markers α-smooth muscle actin (SMA) and desmin using conventional paraffin sections of the proximal and distal bowel. Small bowel from age-matched patients (n = 2) undergoing Meckel’s diverticulum resection served as controls. RESULTS: The smooth muscle coat in the proximal bowel of small bowel atresia patients was thickened compared with control tissue, but the distal bowel was unchanged. Expression of smooth muscle contractile fibres SMA and desmin within the proximal bowel was slightly reduced compared with the distal bowel and control tissue. There were no major differences in the architecture of the smooth muscle within the proximal bowel and the distal bowel. The proximal and distal bowel in small bowel atresia patients revealed only minimal differences regarding smooth muscle morphology and the presence of smooth muscle contractile filament markers. CONCLUSION: Changes in smooth muscle contractile filaments do not appear to play a major role in postoperative motility disorders in small bowel atresia. PMID:22791945

  19. Qishen Yiqi Drop Pill improves cardiac function after myocardial ischemia

    PubMed Central

    JianXin, Chen; Xue, Xu; ZhongFeng, Li; Kuo, Gao; FeiLong, Zhang; ZhiHong, Li; Xian, Wang; HongCai, Shang

    2016-01-01

    Myocardial ischemia (MI) is one of the leading causes of death, while Qishen Yiqi Drop Pill (QYDP) is a representative traditional Chinese medicine to treat this disease. Unveiling the pharmacological mechanism of QYDP will provide a great opportunity to promote the development of novel drugs to treat MI. 64 male Sprague-Dawley (SD) rats were divided into four groups: MI model group, sham operation group, QYDP treatment group and Fosinopril treatment group. Echocardiography results showed that QYDP exhibited significantly larger LV end-diastolic dimension (LVEDd) and LV end-systolic dimension (LVEDs), compared with the MI model group, indicating the improved cardiac function by QYDP. 1H-NMR based metabonomics further identify 9 significantly changed metabolites in the QYDP treatment group, and the QYDP-related proteins based on the protein-metabolite interaction networks and the corresponding pathways were explored, involving the pyruvate metabolism pathway, the retinol metabolism pathway, the tyrosine metabolism pathway and the purine metabolism pathway, suggesting that QYDP was closely associated with blood circulation. ELISA tests were further employed to identify NO synthase (iNOS) and cathepsin K (CTSK) in the networks. For the first time, our work combined experimental and computational methods to study the mechanism of the formula of traditional Chinese medicine. PMID:27075394

  20. Bioactive rosette nanotube-hydroxyapatite nanocomposites improve osteoblast functions.

    PubMed

    Sun, Linlin; Zhang, Lijie; Hemraz, Usha D; Fenniri, Hicham; Webster, Thomas J

    2012-09-01

    Inspired from biological systems, small synthetic organic molecules expressing the hydrogen bonding arrays of the DNA bases guanine and cytosine were prepared, and their self-assembly into rosette nanotubes (RNTs) was investigated. Due to their unique biological, physicochemical, and mechanical properties, RNTs could serve as the next generation of injectable orthopedic materials. In this study, a self-assembling module (termed twin base linkers or TBL) was synthesized, and the corresponding RNTs were used as bioactive components in composites of poly (2-hydroxyethyl methacrylate) (pHEMA) and hydroxyapatite (HA) nanoparticles (termed TBL/HA/pHEMA). The properties of these composites were characterized for solidification time, surface morphology, mechanical properties, and cytocompatibility. The experimental conditions were optimized to achieve solidification within 2-40 min, offering a range of properties for orthopedic applications. Composites with 20 wt% HA nanoparticles had a compressive strength (37.1 MPa) and an ultimate tensile stress (14.7 MPa) similar to that of a natural vertebral disc (5-30 MPa). Specifically, the TBL (0.01 mg/mL)/HA(20 wt%)/pHEMA composites improved long-term functions of osteoblasts (or bone-forming cells) in terms of collagen synthesis, alkaline phosphatase activity, and calcium deposition. Moreover, this composite inhibited fibroblast adhesion, thus decreasing the potential for undesirable fibrous tissue formation. In summary, this in vitro study provided evidence that TBL/HA/pHEMA composites are promising injectable orthopedic implant materials that warrant further mechanistic and in vivo studies. PMID:22530958

  1. Emulsion design to improve the delivery of functional lipophilic components.

    PubMed

    McClements, David Julian

    2010-01-01

    The food industry has used emulsion science and technology for many years to create a diverse range of food products, such as milk, cream, soft drinks, nutritional beverages, dressings, mayonnaise, sauces, dips, deserts, ice cream, margarine, and butter. The majority of these food products are conventional oil-in-water (O/W) or water-in-oil (W/O) type emulsions. Recently, there has been increasing interest within the food industry in either improving or extending the functional performance of foods using novel structured emulsions. This article reviews recent developments in the creation of structured emulsions that could be used by the food and other industries, including nanoemulsions, multiple emulsions, multilayer emulsions, solid lipid particles, and filled hydrogel particles. These structured emulsions can be produced from food-grade [generally recognized as safe (GRAS)] ingredients (e.g., lipids, proteins, polysaccharides, surfactants, and minerals), using simple processing operations (e.g., mixing, homogenizing, and thermal processing). The structure, production, performance, and potential applications of each type of structured emulsion system are discussed. PMID:22129337

  2. Applying Quality Function Deployment Model in Burn Unit Service Improvement.

    PubMed

    Keshtkaran, Ali; Hashemi, Neda; Kharazmi, Erfan; Abbasi, Mehdi

    2014-10-13

    Quality function deployment (QFD) is one of the most effective quality design tools. This study applies QFD technique to improve the quality of the burn unit services in Ghotbedin Hospital in Shiraz, Iran. First, the patients' expectations of burn unit services and their priorities were determined through Delphi method. Thereafter, burn unit service specifications were determined through Delphi method. Further, the relationships between the patients' expectations and service specifications and also the relationships between service specifications were determined through an expert group's opinion. Last, the final importance scores of service specifications were calculated through simple additive weighting method. The findings show that burn unit patients have 40 expectations in six different areas. These expectations are in 16 priority levels. Burn units also have 45 service specifications in six different areas. There are four-level relationships between the patients' expectations and service specifications and four-level relationships between service specifications. The most important burn unit service specifications have been identified in this study. The QFD model developed in the study can be a general guideline for QFD planners and executives. PMID:23884047

  3. Using SVD for improved interferometric Green's function retrieval

    NASA Astrophysics Data System (ADS)

    Melo, Gabriela; Malcolm, Alison; Mikesell, Dylan; van Wijk, Kasper

    2013-09-01

    Seismic interferometry (SI) is a technique used to estimate the Green's function (GF) between two receiver locations, as if there were a source at one of the receiver locations. However, in many applications, the requirements to recover the exact GF are not satisfied and SI yields a poor estimate of the GF. For these non-ideal cases, we improve the interferometric GFs, by applying singular value decomposition (SVD) to the cross-correlations before stacking. The SVD approach preserves energy that is stationary in the cross-correlations, which is the energy that contributes most to the GF recovery, and attenuates non-stationary energy, which leads to artefacts in the interferometric GF. We apply this method to construct virtual shot gathers (for both synthetic and field data) and demonstrate how using SVD enhances physical arrivals in these gathers. We also find that SVD is robust with respect to weakly correlated random noise, allowing a better recovery of events from noisy data, in some cases recovering energy that would otherwise be completely lost in the noise and that the standard SI technique fails to recover.

  4. Magnetic Alignment and Charge Transport Improvement in Functional Soft Materials

    NASA Astrophysics Data System (ADS)

    Majewski, Pawel W.

    The realization of nanostructured functional materials by self-assembly in polymers and polymer nanocomposites is adversely affected by persisting structural defects which greatly diminish the performance of the material. The use of magnetic fields to impose long-range order is investigated in three distinct systems - ion-conducting block copolymers, semiconducting nanowire-polymer composites and lyotropic surfactant mesophases. The alignment process is quantitatively studied with X-ray scattering and microscopic methods. Time and temperature resolved data collected in situ during the magnetic experiments provide an insight into the thermodynamic and kinetic aspects of the process. These data together with simultaneous electrical conductivity measurements allow relating fundamental structural properties (e.g., morphology and long-range order) to transport properties (i.e., conductivity). In particular, it is demonstrated that magnetic fields offer a viable route for improvement of electric conductivity in these systems. More than an order of magnitude increase in conductivity is recorded in magnetically-annealed materials. The resulting aligned nanostructured systems are attractive for ordered solid polymer electrolyte membranes, heterojunction photovoltaic devices and generally help to understand charge transport mechanisms in anisotropic heterogeneous systems.

  5. Stimulus Characteristics for Vestibular Stochastic Resonance to Improve Balance Function

    NASA Technical Reports Server (NTRS)

    Mulavara, Ajitkumar; Fiedler, Matthew; Kofman, Igor; Peters, Brian; Wood, Scott; Serrado, Jorge; Cohen, Helen; Reschke, Millard; Bloomberg, Jacob

    2010-01-01

    Stochastic resonance (SR) is a mechanism by which noise can enhance the response of neural systems to relevant sensory signals. Studies have shown that imperceptible stochastic vestibular electrical stimulation, when applied to normal young and elderly subjects, significantly improved their ocular stabilization reflexes in response to whole-body tilt as well as balance performance during postural disturbances. The goal of this study was to optimize the amplitude characteristics of the stochastic vestibular signals for balance performance during standing on an unstable surface. Subjects performed a standard balance task of standing on a block of foam with their eyes closed. Bipolar stochastic electrical stimulation was applied to the vestibular system using constant current stimulation through electrodes placed over the mastoid process behind the ears. Amplitude of the signals varied in the range of 0-700 microamperes. Balance performance was measured using a force plate under the foam block, and inertial motion sensors were placed on the torso and head. Balance performance with stimulation was significantly greater (10%-25%) than with no stimulation. The signal amplitude at which performance was maximized was in the range of 100-300 microamperes. Optimization of the amplitude of the stochastic signals for maximizing balance performance will have a significant impact on development of vestibular SR as a unique system to aid recovery of function in astronauts after long-duration space flight or in patients with balance disorders.

  6. An improved version of the Green's function molecular dynamics method

    NASA Astrophysics Data System (ADS)

    Kong, Ling Ti; Denniston, Colin; Müser, Martin H.

    2011-02-01

    This work presents an improved version of the Green's function molecular dynamics method (Kong et al., 2009; Campañá and Müser, 2004 [1,2]), which enables one to study the elastic response of a three-dimensional solid to an external stress field by taking into consideration only atoms near the surface. In the previous implementation, the effective elastic coefficients measured at the Γ-point were altered to reduce finite size effects: their eigenvalues corresponding to the acoustic modes were set to zero. This scheme was found to work well for simple Bravais lattices as long as only atoms within the last layer were treated as Green's function atoms. However, it failed to function as expected in all other cases. It turns out that a violation of the acoustic sum rule for the effective elastic coefficients at Γ (Kong, 2010 [3]) was responsible for this behavior. In the new version, the acoustic sum rule is enforced by adopting an iterative procedure, which is found to be physically more meaningful than the previous one. In addition, the new algorithm allows one to treat lattices with bases and the Green's function slab is no longer confined to one layer. New version program summaryProgram title: FixGFC/FixGFMD v1.12 Catalogue identifier: AECW_v1_1 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AECW_v1_1.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 206 436 No. of bytes in distributed program, including test data, etc.: 4 314 850 Distribution format: tar.gz Programming language: C++ Computer: All Operating system: Linux Has the code been vectorized or parallelized?: Yes. Code has been parallelized using MPI directives. RAM: Depends on the problem Classification: 7.7 External routines: LAMMPS ( http://lammps.sandia.gov/), MPI ( http

  7. Lateral hypothalamic lesions cause gastric injury by stimulating gastric contractility.

    PubMed

    Garrick, T; Grijalva, C V; Trauner, M

    1993-07-01

    Changes in gastric contractility following lateral hypothalamic (LH) lesions with and without bilateral cervical vagotomy were measured in urethan-anesthetized rats. LH lesions were induced with direct current passed through stereotaxically placed electrodes. Gastric contractility was recorded continuously for 4 h with acutely implanted strain gauge force transducers and analyzed by computer. LH lesions consistently stimulated gastric contractility and caused more gastric mucosal injury than control conditions. Vagotomy blocked both gastric mucosal injury and high-amplitude gastric contractions. In rats with LH lesions and exogenously infused intragastric hydrochloric acid, atropine methyl nitrate inhibited high-amplitude gastric contractions and gastric erosions. These findings indicate that LH lesions stimulate vagally mediated high-amplitude gastric contractions, which, in the presence of hydrochloric acid, cause gastric mucosal erosions. PMID:8338162

  8. Teneligliptin improves left ventricular diastolic function and endothelial function in patients with diabetes.

    PubMed

    Hashikata, Takehiro; Yamaoka-Tojo, Minako; Kakizaki, Ryota; Nemoto, Teruyoshi; Fujiyoshi, Kazuhiro; Namba, Sayaka; Kitasato, Lisa; Hashimoto, Takuya; Kameda, Ryo; Maekawa, Emi; Shimohama, Takao; Tojo, Taiki; Ako, Junya

    2016-08-01

    Incretin hormones have been reported to have cytoprotective actions in addition to their glucose-lowering effects. We evaluated whether teneligliptin, a novel dipeptidyl peptidase-4 (DPP-4) inhibitor, affects left ventricular (LV) function in patients with type 2 diabetes mellitus (T2DM). Twenty-nine T2DM patients not receiving any incretin-based drugs were enrolled and prescribed with teneligliptin for 3 months. Compared to baseline levels, hemoglobin A1c levels decreased (7.6 ± 1.0 % to 6.9 ± 0.7 %, p < 0.01) and 1,5-anhydro-D-glucitol levels increased (9.6 ± 7.2 μg/mL to 13.5 ± 8.7 μg/mL, p < 0.01) after treatment. Clinical parameters, including body mass index and blood pressure, did not show any difference before and after treatment. Three months after treatment, there were improvements in LV systolic and diastolic function [LV ejection fraction, 62.0 ± 6.5 % to 64.5 ± 5.0 %, p = 0.01; peak early diastolic velocity/basal septal diastolic velocity (E/e') ratio, 13.3 ± 4.1 to 11.9 ± 3.3, p = 0.01]. Moreover, there was an improvement in endothelial function (reactive hyperemia peripheral arterial tonometry [RH-PAT] index; 1.58 ± 0.47 to 2.01 ± 0.72, p < 0.01). There was a significant negative correlation between changes in the E/e' ratio and RH-PAT values. Furthermore, circulating adiponectin levels increased (27.0 ± 38.5 pg/mL to 42.7 ± 33.2 pg/mL, p < 0.01) without changes in patient body weight. Teneligliptin treatment was associated with improvements in LV function and endothelial functions, and an increase in serum adiponectin levels. These results support the cardio-protective effects of teneligliptin in T2DM patients and increase in serum adiponectin levels. PMID:26266630

  9. Exercise training improves endothelial function in young prehypertensives

    PubMed Central

    Beck, Darren T; Casey, Darren P; Martin, Jeffrey S; Emerson, Blaze D; Braith, Randy W

    2015-01-01

    Prehypertensives exhibit marked endothelial dysfunction, a risk factor for future cardiovascular morbidity and mortality. However, the ability of exercise to ameliorate endothelial dysfunction in prehypertensives is grossly underinvestigated. This prospective randomized and controlled study examined the separate effects of resistance and endurance training on conduit artery endothelial function in young prehypertensives. Forty-three unmedicated prehypertensive (systolic blood pressure [SBP]=120–139 mmHg; diastolic blood pressure [DBP]=80–89 mmHg) but otherwise healthy men and women and 15 normotensive matched time-controls (NMTC); n = 15) between 18 and 35 y of age met screening requirements and participated in the study. Prehypertensive subjects were randomly assigned to either a resistance exercise training (PHRT; n = 15), endurance exercise training (PHET; n = 13) or time-control group (PHTC; n = 15). The treatment groups performed exercise training three days per week for eight weeks. The control groups did not initiate exercise programs throughout the study. Flow mediated dilation (FMD) of the brachial artery, biomarkers of enodothelial function and peripheral blood pressure were evaluated before and after exercise intervention or time-matched control. PHRT and PHET reduced resting SBP (9.6 ± 3.6 and 11.9 ± 3.4 mmHg, respectively; P < 0.05) and DBP (8.0 ± 5.1 and 7.2 ± 3.4 mmHg, respectively; P < 0.05). Exercise training improved brachial artery FMD absolute diameter, percent dilation and normalized percent dilation by 30%, 34% and 19% for PHRT, P < 0.05; and by 54%, 63% and 75% for PHET, P < 0.05; respectively. PHRT and PHET increased plasma concentrations of 6-keto prostaglandin F1α (19% and 22%, respectively; P < 0.05), NOx (19% and 23%, respectively; P < 0.05), and reduced endothelin-1 by (16% and 24%, respectively; P < 0.01). This study provides novel evidence that resistance and endurance exercise separately have beneficial effects on resting

  10. Exercise training improves endothelial function in young prehypertensives.

    PubMed

    Beck, Darren T; Casey, Darren P; Martin, Jeffrey S; Emerson, Blaze D; Braith, Randy W

    2013-04-01

    Prehypertensives exhibit marked endothelial dysfunction, a risk factor for future cardiovascular morbidity and mortality. However, the ability of exercise to ameliorate endothelial dysfunction in prehypertensives is grossly underinvestigated. This prospective randomized and controlled study examined the separate effects of resistance and endurance training on conduit artery endothelial function in young prehypertensives. Forty-three unmedicated prehypertensive (systolic blood pressure [SBP]=120-139 mmHg; diastolic blood pressure [DBP]=80-89 mmHg) but otherwise healthy men and women and 15 normotensive matched time-controls (NMTC); n = 15) between 18 and 35 y of age met screening requirements and participated in the study. Prehypertensive subjects were randomly assigned to either a resistance exercise training (PHRT; n = 15), endurance exercise training (PHET; n = 13) or time-control group (PHTC; n = 15). The treatment groups performed exercise training three days per week for eight weeks. The control groups did not initiate exercise programs throughout the study. Flow mediated dilation (FMD) of the brachial artery, biomarkers of enodothelial function and peripheral blood pressure were evaluated before and after exercise intervention or time-matched control. PHRT and PHET reduced resting SBP (9.6 ± 3.6 and 11.9 ± 3.4 mmHg, respectively; P < 0.05) and DBP (8.0 ± 5.1 and 7.2 ± 3.4 mmHg, respectively; P < 0.05). Exercise training improved brachial artery FMD absolute diameter, percent dilation and normalized percent dilation by 30%, 34% and 19% for PHRT, P < 0.05; and by 54%, 63% and 75% for PHET, P < 0.05; respectively. PHRT and PHET increased plasma concentrations of 6-keto prostaglandin F1α (19% and 22%, respectively; P < 0.05), NO x (19% and 23%, respectively; P < 0.05), and reduced endothelin-1 by (16% and 24%, respectively; P < 0.01). This study provides novel evidence that resistance and endurance exercise separately have beneficial effects on resting

  11. 42 CFR 493.2001 - Establishment and function of the Clinical Laboratory Improvement Advisory Committee.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... LABORATORY REQUIREMENTS Consultations § 493.2001 Establishment and function of the Clinical Laboratory Improvement Advisory Committee. (a) HHS will establish a Clinical Laboratory Improvement Advisory Committee to.... (b) The Clinical Laboratory Improvement Advisory Committee will be comprised of individuals...

  12. Strategies for improving the functionality of an affinity bioreactor.

    PubMed

    Wang, Tanya; Yang, Zhiqiang; Emregul, Emel; David, Allan; Balthasar, Joseph P; Liang, Junfeng; Yang, Victor C

    2005-12-01

    gram of fibers was relatively comparable between the OAPA and the previous CNBr activation methods (7.45 mg/g versus 7.69 mg/g fibers), there was virtually no detectable leaching of immobilized protamine from the bioreactor by the OAPA method, comparing to 35% leaching of protamine by the previous CNBr method following 72 h of storage of the bioreactor in PBS buffer at 37 degrees C. To improve the capacity and functionality of the protamine bioreactor, two novel approaches were adopted. Long chain and high molecular weight poly-lysine was linked to the hollow fibers, prior to protamine coupling, to create multiple layers of immobilized protamine for subsequent heparin adsorption. In addition, a poly(ethylene glycol) (PEG) chain was inserted between protamine and the hollow fibers to yield a three-dimensional, free dynamic motion for immobilized protamine. Preliminary observations indicated that a four- to five-fold enhancement in heparin adsorption was attained by utilizing each of these new approaches. Aside from their current use, these new strategies can also be employed generically to improve the functionality of any affinity-type bioreactor. Indeed, efforts have been made recently in utilizing these approaches to develop a clinically usable GPIIb/IIIa bioreactor for the treatment of immune thrombocytopenic purpura (ITP)-an autoimmune disease. PMID:16246511

  13. TRPM4 Is a Novel Component of the Adhesome Required for Focal Adhesion Disassembly, Migration and Contractility

    PubMed Central

    Cáceres, Mónica; Ortiz, Liliana; Recabarren, Tatiana; Romero, Anibal; Colombo, Alicia; Leiva-Salcedo, Elías; Varela, Diego; Rivas, José; Silva, Ian; Morales, Diego; Campusano, Camilo; Almarza, Oscar; Simon, Felipe; Toledo, Hector; Park, Kang-Sik; Trimmer, James S.; Cerda, Oscar

    2015-01-01

    Cellular migration and contractility are fundamental processes that are regulated by a variety of concerted mechanisms such as cytoskeleton rearrangements, focal adhesion turnover, and Ca2+ oscillations. TRPM4 is a Ca2+-activated non-selective cationic channel (Ca2+-NSCC) that conducts monovalent but not divalent cations. Here, we used a mass spectrometry-based proteomics approach to identify putative TRPM4-associated proteins. Interestingly, the largest group of these proteins has actin cytoskeleton-related functions, and among these nine are specifically annotated as focal adhesion-related proteins. Consistent with these results, we found that TRPM4 localizes to focal adhesions in cells from different cellular lineages. We show that suppression of TRPM4 in MEFs impacts turnover of focal adhesions, serum-induced Ca2+ influx, focal adhesion kinase (FAK) and Rac activities, and results in reduced cellular spreading, migration and contractile behavior. Finally, we demonstrate that the inhibition of TRPM4 activity alters cellular contractility in vivo, affecting cutaneous wound healing. Together, these findings provide the first evidence, to our knowledge, for a TRP channel specifically localized to focal adhesions, where it performs a central role in modulating cellular migration and contractility. PMID:26110647

  14. Assessment of the Contractile Properties of Permeabilized Skeletal Muscle Fibers.

    PubMed

    Claflin, Dennis R; Roche, Stuart M; Gumucio, Jonathan P; Mendias, Christopher L; Brooks, Susan V

    2016-01-01

    Permeabilized individual skeletal muscle fibers offer the opportunity to evaluate contractile behavior in a system that is greatly simplified, yet physiologically relevant. Here we describe the steps required to prepare, permeabilize and preserve small samples of skeletal muscle. We then detail the procedures used to isolate individual fiber segments and attach them to an experimental apparatus for the purpose of controlling activation and measuring force generation. We also describe our technique for estimating the cross-sectional area of fiber segments. The area measurement is necessary for normalizing the absolute force to obtain specific force, a measure of the intrinsic force-generating capability of the contractile system. PMID:27492182

  15. Functional motor recovery is improved due to local placement of GDNF microspheres after delayed nerve repair.

    PubMed

    Wood, Matthew D; Gordon, Tessa; Kemp, Stephen W P; Liu, Edward H; Kim, Howard; Shoichet, Molly S; Borschel, Gregory H

    2013-05-01

    The majority of bioengineering strategies to promote peripheral nerve regeneration after injury have focused on therapies to bridge large nerve defects while fewer therapies are being developed to treat other nerve injuries, such as nerve transection. We constructed delivery systems using fibrin gels containing either free GDNF or polylactide-glycolic acid (PLGA) microspheres with GDNF to treat delayed nerve repair, where ELISA verified GDNF release. We determined the formulation of microspheres containing GDNF that optimized nerve regeneration and functional recovery in a rat model of delayed nerve repair. Experimental groups underwent delayed nerve repair and treatment with GDNF microspheres in fibrin glue at the repair site or control treatments (empty microspheres or free GDNF without microspheres). Contractile muscle force, muscle mass, and MUNE were measured 12 weeks following treatment, where GDNF microspheres (2 weeks formulation) were superior compared to either no GDNF or short-term release of free GDNF to nerve. Nerve histology distal to the repair site demonstrated increased axon counts and fiber diameters due to GDNF microspheres (2 weeks formulation). GDNF microspheres partially reversed the deleterious effects of chronic nerve injury, and recovery was slightly favored with the 2 weeks formulation compared to the 4 weeks formulation. PMID:23239194

  16. Automated analysis of contractile force and Ca2+ transients in engineered heart tissue.

    PubMed

    Stoehr, Andrea; Neuber, Christiane; Baldauf, Christina; Vollert, Ingra; Friedrich, Felix W; Flenner, Frederik; Carrier, Lucie; Eder, Alexandra; Schaaf, Sebastian; Hirt, Marc N; Aksehirlioglu, Bülent; Tong, Carl W; Moretti, Alessandra; Eschenhagen, Thomas; Hansen, Arne

    2014-05-01

    Contraction and relaxation are fundamental aspects of cardiomyocyte functional biology. They reflect the response of the contractile machinery to the systolic increase and diastolic decrease of the cytoplasmic Ca(2+) concentration. The analysis of contractile function and Ca(2+) transients is therefore important to discriminate between myofilament responsiveness and changes in Ca(2+) homeostasis. This article describes an automated technology to perform sequential analysis of contractile force and Ca(2+) transients in up to 11 strip-format, fibrin-based rat, mouse, and human fura-2-loaded engineered heart tissues (EHTs) under perfusion and electrical stimulation. Measurements in EHTs under increasing concentrations of extracellular Ca(2+) and responses to isoprenaline and carbachol demonstrate that EHTs recapitulate basic principles of heart tissue functional biology. Ca(2+) concentration-response curves in rat, mouse, and human EHTs indicated different maximal twitch forces (0.22, 0.05, and 0.08 mN in rat, mouse, and human, respectively; P < 0.001) and different sensitivity to external Ca(2+) (EC50: 0.15, 0.39, and 1.05 mM Ca(2+) in rat, mouse, and human, respectively; P < 0.001) in the three groups. In contrast, no difference in myofilament Ca(2+) sensitivity was detected between skinned rat and human EHTs, suggesting that the difference in sensitivity to external Ca(2+) concentration is due to changes in Ca(2+) handling proteins. Finally, this study confirms that fura-2 has Ca(2+) buffering effects and is thereby changing the force response to extracellular Ca(2+). PMID:24585781

  17. Contribution of increased VEGF receptors to hypoxic changes in fetal ovine carotid artery contractile proteins.

    PubMed

    Adeoye, Olayemi O; Butler, Stacy M; Hubbell, Margaret C; Semotiuk, Andrew; Williams, James M; Pearce, William J

    2013-04-01

    Recent studies suggest that vascular endothelial growth factor (VEGF) can modulate smooth muscle phenotype and, consequently, the composition and function of arteries upstream from the microcirculation, where angiogenesis occurs. Given that hypoxia potently induces VEGF, the present study explores the hypothesis that, in fetal arteries, VEGF contributes to hypoxic vascular remodeling through changes in abundance, organization, and function of contractile proteins. Pregnant ewes were acclimatized at sea level or at altitude (3,820 m) for the final 110 days of gestation. Endothelium-denuded carotid arteries from full-term fetuses were used fresh or after 24 h of organ culture in a physiological concentration (3 ng/ml) of VEGF. After 110 days, hypoxia had no effect on VEGF abundance but markedly increased abundance of the Flk-1 (171%) and Flt-1 (786%) VEGF receptors. Hypoxia had no effect on smooth muscle α-actin (SMαA), decreased myosin light chain (MLC) kinase (MLCK), and increased 20-kDa regulatory MLC (MLC(20)) abundances. Hypoxia also increased MLCK-SMαA, MLC(20)-SMαA, and MLCK-MLC(20) colocalization. Compared with hypoxia, organ culture with VEGF produced the same pattern of changes in contractile protein abundance and colocalization. Effects of VEGF on colocalization were blocked by the VEGF receptor antagonists vatalanib (240 nM) and dasatinib (6.3 nM). Thus, through increases in VEGF receptor density, hypoxia can recruit VEGF to help mediate remodeling of fetal arteries upstream from the microcirculation. The results support the hypothesis that VEGF contributes to hypoxic vascular remodeling through changes in abundance, organization, and function of contractile proteins. PMID:23325408

  18. Contractile properties of muscle fibers from the deep and superficial digital flexors of horses

    PubMed Central

    Chase, P. B.; Hermanson, J. W.; Clark, A. N.; Brunet, N. M.; Bertram, J. E. A.

    2010-01-01

    Equine digital flexor muscles have independent tendons but a nearly identical mechanical relationship to the main joint they act upon. Yet these muscles have remarkable diversity in architecture, ranging from long, unipennate fibers (“short” compartment of DDF) to very short, multipennate fibers (SDF). To investigate the functional relevance of the form of the digital flexor muscles, fiber contractile properties were analyzed in the context of architecture differences and in vivo function during locomotion. Myosin heavy chain (MHC) isoform fiber type was studied, and in vitro motility assays were used to measure actin filament sliding velocity (Vf). Skinned fiber contractile properties [isometric tension (P0/CSA), velocity of unloaded shortening (VUS), and force-Ca2+ relationships] at both 10 and 30°C were characterized. Contractile properties were correlated with MHC isoform and their respective Vf. The DDF contained a higher percentage of MHC-2A fibers with myosin (heavy meromyosin) and Vf that was twofold faster than SDF. At 30°C, P0/CSA was higher for DDF (103.5 ± 8.75 mN/mm2) than SDF fibers (81.8 ± 7.71 mN/mm2). Similarly, VUS (pCa 5, 30°C) was faster for DDF (2.43 ± 0.53 FL/s) than SDF fibers (1.20 ± 0.22 FL/s). Active isometric tension increased with increasing Ca2+ concentration, with maximal Ca2+ activation at pCa 5 at each temperature in fibers from each muscle. In general, the collective properties of DDF and SDF were consistent with fiber MHC isoform composition, muscle architecture, and the respective functional roles of the two muscles in locomotion. PMID:20702801

  19. Automated analysis of contractile force and Ca2+ transients in engineered heart tissue

    PubMed Central

    Stoehr, Andrea; Neuber, Christiane; Baldauf, Christina; Vollert, Ingra; Friedrich, Felix W.; Flenner, Frederik; Carrier, Lucie; Eder, Alexandra; Schaaf, Sebastian; Hirt, Marc N.; Aksehirlioglu, Bülent; Tong, Carl W.; Moretti, Alessandra; Eschenhagen, Thomas

    2014-01-01

    Contraction and relaxation are fundamental aspects of cardiomyocyte functional biology. They reflect the response of the contractile machinery to the systolic increase and diastolic decrease of the cytoplasmic Ca2+ concentration. The analysis of contractile function and Ca2+ transients is therefore important to discriminate between myofilament responsiveness and changes in Ca2+ homeostasis. This article describes an automated technology to perform sequential analysis of contractile force and Ca2+ transients in up to 11 strip-format, fibrin-based rat, mouse, and human fura-2-loaded engineered heart tissues (EHTs) under perfusion and electrical stimulation. Measurements in EHTs under increasing concentrations of extracellular Ca2+ and responses to isoprenaline and carbachol demonstrate that EHTs recapitulate basic principles of heart tissue functional biology. Ca2+ concentration-response curves in rat, mouse, and human EHTs indicated different maximal twitch forces (0.22, 0.05, and 0.08 mN in rat, mouse, and human, respectively; P < 0.001) and different sensitivity to external Ca2+ (EC50: 0.15, 0.39, and 1.05 mM Ca2+ in rat, mouse, and human, respectively; P < 0.001) in the three groups. In contrast, no difference in myofilament Ca2+ sensitivity was detected between skinned rat and human EHTs, suggesting that the difference in sensitivity to external Ca2+ concentration is due to changes in Ca2+ handling proteins. Finally, this study confirms that fura-2 has Ca2+ buffering effects and is thereby changing the force response to extracellular Ca2+. PMID:24585781

  20. Electrical properties and fusion dynamics of in vitro membrane vesicles derived from separate parts of the contractile vacuole complex of Paramecium multimicronucleatum.

    PubMed

    Sugino, Kazuyuki; Tominaga, Takashi; Allen, Richard D; Naitoh, Yutaka

    2005-10-01

    The contractile vacuole complex of Paramecium multimicronucleatum transforms into membrane-bound vesicles on excision from the cell. The I-V relationship was linear in a voltage range of -80 to +80 mV in all vesicles, despite being derived from different parts of the contractile vacuole complex. No voltage-gated unit currents were observed in membrane patches from the vesicles. Vesicles derived from the radial arm showed a membrane potential of >10 mV, positive with reference to the cytosol, while those derived from the contractile vacuole showed a residual (<5 mV) membrane potential. The electrogenic V-ATPases in the decorated spongiome are responsible for the positive potential, and Cl- leakage channels are responsible for the residual potential. The specific resistance of the vesicle membrane (approximately 6 kOmega cm2) increased, while the membrane potential shifted in a negative direction when the vesicle rounded. An increase in the membrane tension (to approximately 5 x 10(-3) N m(-1)) is assumed to reduce the Cl- leakage conductance. It is concluded that neither voltage- nor mechano-sensitive ion channels are involved in the control of the fluid segregation and membrane dynamics that govern fluid discharge cycles in the contractile vacuole complex. The membrane vesicles shrank when the external osmolarity was increased, and swelled when the osmolarity was decreased, implying that the contractile vacuole complex membrane is water permeable. The water permeability of the membrane was 4-20 x 10(-7) microm s(-1) Pa(-1). The vesicles containing radial arm membrane swelled after initially shrinking when exposed to higher external osmolarity, implying that the V-ATPases energize osmolyte transport mechanisms that remain functional in the vesicle membrane. The vesicles showed an abrupt (<30 ms), slight, slackening after rounding to the maximum extent. Similar slackening was also observed in the contractile vacuoles in situ before the opening of the contractile

  1. Improving Sensorimotor Function and Adaptation using Stochastic Vestibular Stimulation

    NASA Technical Reports Server (NTRS)

    Galvan, R. C.; Bloomberg, J. J.; Mulavara, A. P.; Clark, T. K.; Merfeld, D. M.; Oman, C. M.

    2014-01-01

    Astronauts experience sensorimotor changes during adaption to G-transitions that occur when entering and exiting microgravity. Post space flight, these sensorimotor disturbances can include postural and gait instability, visual performance changes, manual control disruptions, spatial disorientation, and motion sickness, all of which can hinder the operational capabilities of the astronauts. Crewmember safety would be significantly increased if sensorimotor changes brought on by gravitational changes could be mitigated and adaptation could be facilitated. The goal of this research is to investigate and develop the use of electrical stochastic vestibular stimulation (SVS) as a countermeasure to augment sensorimotor function and facilitate adaptation. For this project, SVS will be applied via electrodes on the mastoid processes at imperceptible amplitude levels. We hypothesize that SVS will improve sensorimotor performance through the phenomena of stochastic resonance, which occurs when the response of a nonlinear system to a weak input signal is optimized by the application of a particular nonzero level of noise. In line with the theory of stochastic resonance, a specific optimal level of SVS will be found and tested for each subject [1]. Three experiments are planned to investigate the use of SVS in sensory-dependent tasks and performance. The first experiment will aim to demonstrate stochastic resonance in the vestibular system through perception based motion recognition thresholds obtained using a 6-degree of freedom Stewart platform in the Jenks Vestibular Laboratory at Massachusetts Eye and Ear Infirmary. A range of SVS amplitudes will be applied to each subject and the subjectspecific optimal SVS level will be identified as that which results in the lowest motion recognition threshold, through previously established, well developed methods [2,3,4]. The second experiment will investigate the use of optimal SVS in facilitating sensorimotor adaptation to system

  2. Human colonic smooth muscle: electrical and contractile activity in vitro.

    PubMed Central

    Gill, R C; Cote, K R; Bowes, K L; Kingma, Y J

    1986-01-01

    Extracellular electrical and contractile activities were recorded in vitro from strips of human colonic smooth muscle obtained at the time of surgery. Serosal electrical activity of longitudinally oriented strips from the taenia and intertaenial region was characterised by continuous oscillation at a frequency of 28 +/- 1/min. Contractions were marked electrically by a series of oscillations upon which spikes were superimposed. The electrical activity recorded from the submucosal surface of circularly oriented strips exhibited oscillations at 24 +/- 4/min, a frequency significantly lower (p less than 0.001) than that recorded from the serosal surface of similar preparations. The contractile force and frequency was dependent upon the part of the colon from which the strip originated; the most powerful contractions were recorded from strips of sigmoid colon. The contractile frequency of circularly oriented strips from the right colon was 6.3 +/- 0.6/min, significantly higher (p less than 0.001) than that of strips from the left colon (3.4 +/- 0.3/min). Stretching these strips caused an increase in contractile frequency to that of the electrical oscillation. PMID:3699550

  3. Oleanolic acid: a novel cardioprotective agent that blunts hyperglycemia-induced contractile dysfunction.

    PubMed

    Mapanga, Rudo F; Rajamani, Uthra; Dlamini, Nonkululeko; Zungu-Edmondson, Makhosazane; Kelly-Laubscher, Roisin; Shafiullah, Mohammed; Wahab, Athiq; Hasan, Mohamed Y; Fahim, Mohamed A; Rondeau, Philippe; Bourdon, Emmanuel; Essop, M Faadiel

    2012-01-01

    Diabetes constitutes a major health challenge. Since cardiovascular complications are common in diabetic patients this will further increase the overall burden of disease. Furthermore, stress-induced hyperglycemia in non-diabetic patients with acute myocardial infarction is associated with higher in-hospital mortality. Previous studies implicate oxidative stress, excessive flux through the hexosamine biosynthetic pathway (HBP) and a dysfunctional ubiquitin-proteasome system (UPS) as potential mediators of this process. Since oleanolic acid (OA; a clove extract) possesses antioxidant properties, we hypothesized that it attenuates acute and chronic hyperglycemia-mediated pathophysiologic molecular events (oxidative stress, apoptosis, HBP, UPS) and thereby improves contractile function in response to ischemia-reperfusion. We employed several experimental systems: 1) H9c2 cardiac myoblasts were exposed to 33 mM glucose for 48 hr vs. controls (5 mM glucose); and subsequently treated with two OA doses (20 and 50 µM) for 6 and 24 hr, respectively; 2) Isolated rat hearts were perfused ex vivo with Krebs-Henseleit buffer containing 33 mM glucose vs. controls (11 mM glucose) for 60 min, followed by 20 min global ischemia and 60 min reperfusion ± OA treatment; 3) In vivo coronary ligations were performed on streptozotocin treated rats ± OA administration during reperfusion; and 4) Effects of long-term OA treatment (2 weeks) on heart function was assessed in streptozotocin-treated rats. Our data demonstrate that OA treatment blunted high glucose-induced oxidative stress and apoptosis in heart cells. OA therapy also resulted in cardioprotection, i.e. for ex vivo and in vivo rat hearts exposed to ischemia-reperfusion under hyperglycemic conditions. In parallel, we found decreased oxidative stress, apoptosis, HBP flux and proteasomal activity following ischemia-reperfusion. Long-term OA treatment also improved heart function in streptozotocin-diabetic rats. These findings are

  4. NAD(P)H oxidase subunit p47phox is elevated, and p47phox knockout prevents diaphragm contractile dysfunction in heart failure.

    PubMed

    Ahn, Bumsoo; Beharry, Adam W; Frye, Gregory S; Judge, Andrew R; Ferreira, Leonardo F

    2015-09-01

    Patients with chronic heart failure (CHF) have dyspnea and exercise intolerance, which are caused in part by diaphragm abnormalities. Oxidants impair diaphragm contractile function, and CHF increases diaphragm oxidants. However, the specific source of oxidants and its relevance to diaphragm abnormalities in CHF is unclear. The p47(phox)-dependent Nox2 isoform of NAD(P)H oxidase is a putative source of diaphragm oxidants. Thus, we conducted our study with the goal of determining the effects of CHF on the diaphragm levels of Nox2 complex subunits and test the hypothesis that p47(phox) knockout prevents diaphragm contractile dysfunction elicited by CHF. CHF caused a two- to sixfold increase (P < 0.05) in diaphragm mRNA and protein levels of several Nox2 subunits, with p47(phox) being upregulated and hyperphosphorylated. CHF increased diaphragm extracellular oxidant emission in wild-type but not p47(phox) knockout mice. Diaphragm isometric force, shortening velocity, and peak power were decreased by 20-50% in CHF wild-type mice (P < 0.05), whereas p47(phox) knockout mice were protected from impairments in diaphragm contractile function elicited by CHF. Our experiments show that p47(phox) is upregulated and involved in the increased oxidants and contractile dysfunction in CHF diaphragm. These findings suggest that a p47(phox)-dependent NAD(P)H oxidase mediates the increase in diaphragm oxidants and contractile dysfunction in CHF. PMID:26209274

  5. Improving Treatment Integrity through a Functional Approach to Intervention Support

    ERIC Educational Resources Information Center

    Liaupsin, Carl J.

    2015-01-01

    A functional approach to intervention planning has been shown to be effective in reducing problem behaviors and promoting appropriate behaviors in children and youth with behavior disorders. When function-based intervention plans are not successful, it is often due to issues of treatment integrity in which teachers omit or do not sufficiently…

  6. Bladder Smooth Muscle Strip Contractility as a Method to Evaluate Lower Urinary Tract Pharmacology

    PubMed Central

    Kullmann, F. Aura; Daugherty, Stephanie L.; de Groat, William C.; Birder, Lori A.

    2015-01-01

    We describe an in vitro method to measure bladder smooth muscle contractility, and its use for investigating physiological and pharmacological properties of the smooth muscle as well as changes induced by pathology. This method provides critical information for understanding bladder function while overcoming major methodological difficulties encountered in in vivo experiments, such as surgical and pharmacological manipulations that affect stability and survival of the preparations, the use of human tissue, and/or the use of expensive chemicals. It also provides a way to investigate the properties of each bladder component (i.e. smooth muscle, mucosa, nerves) in healthy and pathological conditions. The urinary bladder is removed from an anesthetized animal, placed in Krebs solution and cut into strips. Strips are placed into a chamber filled with warm Krebs solution. One end is attached to an isometric tension transducer to measure contraction force, the other end is attached to a fixed rod. Tissue is stimulated by directly adding compounds to the bath or by electric field stimulation electrodes that activate nerves, similar to triggering bladder contractions in vivo. We demonstrate the use of this method to evaluate spontaneous smooth muscle contractility during development and after an experimental spinal cord injury, the nature of neurotransmission (transmitters and receptors involved), factors involved in modulation of smooth muscle activity, the role of individual bladder components, and species and organ differences in response to pharmacological agents. Additionally, it could be used for investigating intracellular pathways involved in contraction and/or relaxation of the smooth muscle, drug structure-activity relationships and evaluation of transmitter release. The in vitro smooth muscle contractility method has been used extensively for over 50 years, and has provided data that significantly contributed to our understanding of bladder function as well as to

  7. Testosterone regulates smooth muscle contractile pathways in the rat prostate: emphasis on PDE5 signaling

    PubMed Central

    Zhang, Xinhua; Zang, Ning; Wei, Yu; Yin, Jin; Teng, Ruobing; Seftel, Allen

    2012-01-01

    Testosterone (T) plays a permissive role in the development of benign prostatic hyperplasia (BPH), and phosphodiesterase 5 inhibitors (PDE5is) have been found to be effective for BPH and lower urinary tract symptoms (LUTS) in clinical trials. This study investigated the effect of T on smooth muscle (SM) contractile and regulatory signaling pathways, including PDE5 expression and functional activity in prostate in male rats (sham-operated, surgically castrated, and castrated with T supplementation). In vitro organ bath studies, real-time RT-PCR, Western blot analysis, and immunohistochemistry were performed. Castration heavily attenuated contractility, including sensitivity to phenylephrine with SM myosin immunostaining revealing a disrupted SM cell arrangement in the stroma. PDE5 was immunolocalized exclusively in the prostate stroma, and orchiectomy signficantly reduced PDE5 immunopositivity, mRNA, and protein expression, along with nNOS and ROKβ mRNA, whereas it increased eNOS plus α1a and α1b adrenoreceptor expression in castrated animals. The PDE5i zaprinast significantly increased prostate strip relaxation to the nitric oxide donor sodium nitroprusside (SNP) in control but not castrated rats. But SNP alone was more effective on castrated rats, comparable with sham treated with SNP plus zaprinast. T supplementation prevented or restored all above changes, including SNP and zaprinast in vitro responsiveness. In conclusion, our data show that T positively regulates PDE5 expression and functional activities in prostate, and T ablation not only suppresses prostate size but also reduces prostatic SM contractility, with several potential SM contraction/relaxation pathways implicated. Zaprinast findings strongly suggest a major role for PDE5/cGMP in this signaling cascade. PDE5 inhibition may represent a novel mechanism for treatment of BPH. PMID:22028410

  8. Relation of coronary microvascular dysfunction in hypertrophic cardiomyopathy to contractile dysfunction independent from myocardial injury.

    PubMed

    Timmer, Stefan A J; Germans, Tjeerd; Götte, Marco J W; Rüssel, Iris K; Lubberink, Mark; Ten Berg, Jurrien M; Ten Cate, Folkert J; Lammertsma, Adriaan A; Knaapen, Paul; van Rossum, Albert C

    2011-05-15

    We studied the spatial relations among hyperemic myocardial blood flow (hMBF), contractile function, and morphologic tissue alterations in 19 patients with hypertrophic cardiomyopathy (HC). All patients were studied with oxygen-15 water positron emission tomography during rest and adenosine administration to assess myocardial perfusion. Cardiovascular magnetic resonance was performed to derive delayed contrast-enhanced images and to calculate contractile function (E(cc)) with tissue tagging. Eleven healthy subjects underwent similar positron emission tomographic and cardiovascular magnetic resonance scanning protocols and served as a control group. In the HC group, hMBF averaged 2.46 ± 0.91 ml/min/g and mean E(cc) was -14.7 ± 3.4%, which were decreased compared to the control group (3.97 ± 1.48 ml/min/g and -17.7 ± 3.2%, respectively, p <0.001 for the 2 comparisons). Delayed contrast enhancement (DCE) was present only in patients with HC, averaging 6.2 ± 10.3% of left ventricular mass. In the HC group, E(cc) and DCE in the septum (-13.7 ± 3.6% and 10.2 ± 13.6%) significantly differed from the lateral wall (-16.0 ± 2.8% and 2.4 ± 5.9%, p <0.001 for the 2 comparisons). In general, hMBF and E(cc) were decreased in segments displaying DCE compared to nonenhanced segments (p <0.001 for the comparisons). In the HC group, univariate analysis revealed relations of hMBF to E(cc) (r = -0.45, p <0.001) and DCE (r = -0.31, p <0.001). Multivariate analysis revealed that E(cc) was independently related to hMBF (beta -0.37, p <0.001) and DCE (beta 0.28, p <0.001). In conclusion, in HC hMBF is impaired and related to contractile function independent from presence of DCE. When present, DCE reflected a progressed disease state as characterized by an increased perfusion deficit and contractile dysfunction. PMID:21377644

  9. Enzyme replacement therapy rescues weakness and improves muscle pathology in mice with X-linked myotubular myopathy

    PubMed Central

    Lawlor, Michael W.; Armstrong, Dustin; Viola, Marissa G.; Widrick, Jeffrey J.; Meng, Hui; Grange, Robert W.; Childers, Martin K.; Hsu, Cynthia P.; O'Callaghan, Michael; Pierson, Christopher R.; Buj-Bello, Anna; Beggs, Alan H.

    2013-01-01

    No effective treatment exists for patients with X-linked myotubular myopathy (XLMTM), a fatal congenital muscle disease caused by deficiency of the lipid phosphatase, myotubularin. The Mtm1δ4 and Mtm1 p.R69C mice model severely and moderately symptomatic XLMTM, respectively, due to differences in the degree of myotubularin deficiency. Contractile function of intact extensor digitorum longus (EDL) and soleus muscles from Mtm1δ4 mice, which produce no myotubularin, is markedly impaired. Contractile forces generated by chemically skinned single fiber preparations from Mtm1δ4 muscle were largely preserved, indicating that weakness was largely due to impaired excitation contraction coupling. Mtm1 p.R69C mice, which produce small amounts of myotubularin, showed impaired contractile function only in EDL muscles. Short-term replacement of myotubularin with a prototypical targeted protein replacement agent (3E10Fv-MTM1) in Mtm1δ4 mice improved contractile function and muscle pathology. These promising findings suggest that even low levels of myotubularin protein replacement can improve the muscle weakness and reverse the pathology that characterizes XLMTM. PMID:23307925

  10. Integrated Analysis of Contractile Kinetics, Force Generation, and Electrical Activity in Single Human Stem Cell-Derived Cardiomyocytes.

    PubMed

    Kijlstra, Jan David; Hu, Dongjian; Mittal, Nikhil; Kausel, Eduardo; van der Meer, Peter; Garakani, Arman; Domian, Ibrahim J

    2015-12-01

    The quantitative analysis of cardiomyocyte function is essential for stem cell-based approaches for the in vitro study of human cardiac physiology and pathophysiology. We present a method to comprehensively assess the function of single human pluripotent stem cell-derived cardiomyocyte (hPSC-CMs) through simultaneous quantitative analysis of contraction kinetics, force generation, and electrical activity. We demonstrate that statistical analysis of movies of contracting hPSC-CMs can be used to quantify changes in cellular morphology over time and compute contractile kinetics. Using a biomechanical model that incorporates substrate stiffness, we calculate cardiomyocyte force generation at single-cell resolution and validate this approach with conventional traction force microscopy. The addition of fluorescent calcium indicators or membrane potential dyes allows the simultaneous analysis of contractility and calcium handling or action potential morphology. Accordingly, our approach has the potential for broad application in the study of cardiac disease, drug discovery, and cardiotoxicity screening. PMID:26626178

  11. Integrated Analysis of Contractile Kinetics, Force Generation, and Electrical Activity in Single Human Stem Cell-Derived Cardiomyocytes

    PubMed Central

    Kijlstra, Jan David; Hu, Dongjian; Mittal, Nikhil; Kausel, Eduardo; van der Meer, Peter; Garakani, Arman; Domian, Ibrahim J.

    2015-01-01

    Summary The quantitative analysis of cardiomyocyte function is essential for stem cell-based approaches for the in vitro study of human cardiac physiology and pathophysiology. We present a method to comprehensively assess the function of single human pluripotent stem cell-derived cardiomyocyte (hPSC-CMs) through simultaneous quantitative analysis of contraction kinetics, force generation, and electrical activity. We demonstrate that statistical analysis of movies of contracting hPSC-CMs can be used to quantify changes in cellular morphology over time and compute contractile kinetics. Using a biomechanical model that incorporates substrate stiffness, we calculate cardiomyocyte force generation at single-cell resolution and validate this approach with conventional traction force microscopy. The addition of fluorescent calcium indicators or membrane potential dyes allows the simultaneous analysis of contractility and calcium handling or action potential morphology. Accordingly, our approach has the potential for broad application in the study of cardiac disease, drug discovery, and cardiotoxicity screening. PMID:26626178

  12. The process of performance improvement: preserving myocardial function.

    PubMed

    Washington, G T

    2001-01-01

    In today's healthcare environment, the continual assessment of processes is necessary to provide the best patient care. Ongoing process improvement also is helpful in organizations' remaining both competitive and fiscally viable. Because of the increasing concern about mortality rates from acute myocardial infarction (AMI), the Johnson City Medical Center chose to evaluate the care of patients with AMI. This article describes the first of three phases of the hospital's efforts to examine and improve the process of caring for patients with AMI to achieve positive patient outcomes. PMID:11565169

  13. Hypnotic Relaxation and Yoga to Improve Sleep and School Functioning

    ERIC Educational Resources Information Center

    Perfect, Michelle M.; Smith, Bradley

    2016-01-01

    Sleep insufficiency, defined as inadequate sleep duration, poor sleep quality, and daytime sleepiness, has been linked with students' learning and behavioral outcomes at school. However, there is limited research on interventions designed to improve the sleep of school-age children. In order to promote more interest on this critical topic, we…

  14. Neurofeedback Improves Executive Functioning in Children with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Kouijzer, Mirjam E. J.; de Moor, Jan M. H.; Gerrits, Berrie J. L.; Congedo, Marco; van Schie, Hein T.

    2009-01-01

    Seven autistic children diagnosed with autism spectrum disorders (ASD) received a neurofeedback treatment that aimed to improve their level of executive control. Neurofeedback successfully reduced children's heightened theta/beta ratio by inhibiting theta activation and enhancing beta activation over sessions. Following treatment, children's…

  15. Bi-content micro-collagen chip provides contractility-based biomechanical readout for phenotypic drug screening with expanded and profiled targets.

    PubMed

    Zhao, Hui; Zhou, Lyu; Zhang, Qiang; Zhou, Xiaoying; Zhang, Yonghui; Chen, Huijun; Du, Yanan

    2015-09-01

    Phenotypic screening has regained momentum in the pharmaceutical industry owing to its success over target-based screening. Most phenotypic screening relies on nonspecific biochemical readouts regarding cellular viability, which hampers the discovery of novel drug mechanisms of action (MOAs). Here we present a Contractility-based bi-Content micro-Collagen Chip (3CChip), which establishes cellular contractility as a biomechanics-related phenotype for drug screening. Bi-content analysis of cell contractility (imaged by iPhone) and viability suggests that the label-free contractility-based analysis exhibits superior sensitivity to compounds targeting contractile elements (e.g. focal adhesion, cytoskeleton), resulting in a enlarged target pool for drug assessment. Six typical readout patterns of drug response are summarized according to the relative positions of the contraction/viability curves, and drug targets are profiled into three categories (biomechanical, biochemical and housekeeping) by 3CChip, which will benefit subsequent target identification. The simple-to-use and effective 3CChip offers a robust platform for micro-tissue-based functional screening and may lead to a new era of mechanism-informed phenotypic drug discovery. PMID:26219255

  16. Myoblasts transplanted into rat infarcted myocardium are functionally isolated from their host

    PubMed Central

    Léobon, Bertrand; Garcin, Isabelle; Menasché, Philippe; Vilquin, Jean-Thomas; Audinat, Etienne; Charpak, Serge

    2003-01-01

    Survival and differentiation of myogenic cells grafted into infarcted myocardium have raised the hope that cell transplantation becomes a new therapy for cardiovascular diseases. The approach was further supported by transplantation of skeletal myoblasts, which was shown to improve cardiac performance in several animal species. Despite the success of myoblast transplantation and its recent trial in human, the mechanism responsible for the functional improvement remains unclear. Here, we used intracellular recordings coupled to video and fluorescence microscopy to establish whether myoblasts, genetically labeled with enhanced GFP and transplanted into rat infarcted myocardium, retain excitable and contractile properties, and participate actively to cardiac function. Our results indicate that grafted myoblasts differentiate into peculiar hyperexcitable myotubes with a contractile activity fully independent of neighboring cardiomyocytes. We conclude that mechanisms other than electromechanical coupling between grafted and host cells are involved in the improvement of cardiac function. PMID:12805561

  17. Red raspberries can improve motor function in aged rats

    Technology Transfer Automated Retrieval System (TEKTRAN)

    BACKGROUND: Many foods rich in antioxidant and anti-inflammatory compounds have been shown to increase health and reduce markers of aging. A number of berry fruits high in polyphenols are known to ameliorate age-related declines in cellular, cognitive and behavioral function in rats. OBJECTIVES: Thi...

  18. High-Throughput Screening of Myometrial Calcium-Mobilization to Identify Modulators of Uterine Contractility

    PubMed Central

    Herington, Jennifer L.; Swale, Daniel R.; Brown, Naoko; Shelton, Elaine L.; Choi, Hyehun; Williams, Charles H.; Hong, Charles C.; Paria, Bibhash C.; Denton, Jerod S.; Reese, Jeff

    2015-01-01

    The uterine myometrium (UT-myo) is a therapeutic target for preterm labor, labor induction, and postpartum hemorrhage. Stimulation of intracellular Ca2+-release in UT-myo cells by oxytocin is a final pathway controlling myometrial contractions. The goal of this study was to develop a dual-addition assay for high-throughput screening of small molecular compounds, which could regulate Ca2+-mobilization in UT-myo cells, and hence, myometrial contractions. Primary murine UT-myo cells in 384-well plates were loaded with a Ca2+-sensitive fluorescent probe, and then screened for inducers of Ca2+-mobilization and inhibitors of oxytocin-induced Ca2+-mobilization. The assay exhibited robust screening statistics (Z´ = 0.73), DMSO-tolerance, and was validated for high-throughput screening against 2,727 small molecules from the Spectrum, NIH Clinical I and II collections of well-annotated compounds. The screen revealed a hit-rate of 1.80% for agonist and 1.39% for antagonist compounds. Concentration-dependent responses of hit-compounds demonstrated an EC50 less than 10μM for 21 hit-antagonist compounds, compared to only 7 hit-agonist compounds. Subsequent studies focused on hit-antagonist compounds. Based on the percent inhibition and functional annotation analyses, we selected 4 confirmed hit-antagonist compounds (benzbromarone, dipyridamole, fenoterol hydrobromide and nisoldipine) for further analysis. Using an ex vivo isometric contractility assay, each compound significantly inhibited uterine contractility, at different potencies (IC50). Overall, these results demonstrate for the first time that high-throughput small-molecules screening of myometrial Ca2+-mobilization is an ideal primary approach for discovering modulators of uterine contractility. PMID:26600013

  19. Active self-polarization of contractile cells in asymmetrically shaped domains.

    PubMed

    Zemel, A; Safran, S A

    2007-08-01

    Mechanical forces generated by contractile cells allow the cells to sense their environment and to interact with other cells. By locally pulling on their environment, cells can sense and respond to mechanical features such as the local stress (or strain), the shape of a cellular domain, and the surrounding rigidity; at the same time, they also modify the mechanical state of the system. This creates a mechanical feedback loop that can result in self-polarization of cells. In this paper, we present a quantitative mechanical model that predicts the self-polarization of cells in spheroidally shaped domains, comprising contractile cells and an elastic matrix, that are embedded in a three-dimensional, cell-free gel. The theory is based on a generalization of the known results for passive inclusions in solids to include the effects of cell activity. We use the active cellular susceptibility tensor presented by Zemel [Phys. Rev. Lett. 97, 128103 (2006)] to calculate the polarization response and hence the elastic stress field developed by the cells in the cellular domain. The cell polarization is analyzed as a function of the shape and the elastic moduli of the cellular domain compared with the cell-free surrounding material. Consistent with experiment, our theory predicts the development of a stronger contractile force for cells in a gel that is surrounded by a large, cell-free material whose elastic modulus is stiffer than that of the gel that contains the cells. This provides a quantitative explanation of the differences in the development of cellular forces as observed in free and fixed gels. In the case of an asymmetrically shaped (spheroidal) domain of cells, we show that the anisotropic elastic field within the domain leads to a spontaneous self-polarization of the cells along the long axis of the domain. PMID:17930063

  20. Cardiac-specific overexpression of metallothionein rescues nicotine-induced cardiac contractile dysfunction and interstitial fibrosis.

    PubMed

    Hu, Nan; Guo, Rui; Han, Xuefeng; Zhu, Baocheng; Ren, Jun

    2011-04-10

    Cigarette smoking is a devastating risk factor for cardiovascular diseases and nicotine is believed the main toxin component responsible for the toxic myocardial effects of smoking. Nonetheless, neither the precise mechanism of nicotine-induced cardiac dysfunction nor effective treatment is elucidated. The aim of this study was to evaluate the impact of cardiac-specific overexpression of heavy metal scavenger metallothionein on myocardial geometry and mechanical function following nicotine exposure. Adult male friend virus B (FVB) wild-type and metallothionein mice were injected with nicotine (2 mg/kg/d) intraperitoneally for 10 days. Mechanical and intracellular Ca²+ properties were examined. Myocardial histology (cross-sectional area and fibrosis) was evaluated by hematoxylin and eosin (H&E) and Masson trichrome staining, respectively. Oxidative stress and apoptosis were measured by fluoroprobe 5-(6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate (CM-H₂DCFDA) fluorescence and caspase-3 activity, respectively. Nicotine exposure failed to affect the protein abundance of metallothionein. Our data revealed reduced echocardiographic contractile capacity (fractional shortening), altered cardiomyocyte contractile and intracellular Ca²+ properties including depressed peak shortening amplitude, maximal velocity of shortening/relengthening, resting and electrically-stimulated rise in intracellular Ca²+, as well as prolonged duration of relengthening and intracellular Ca²+ clearance in hearts from nicotine-treated FVB mice, the effect of which was ameliorated by metallothionein. Biochemical and histological findings depicted overt accumulation of reactive oxygen species (ROS), apoptosis and myocardial fibrosis without any change in myocardial cross-sectional area following nicotine treatment, which was mitigated by metallothionein. Taken together, our findings suggest the antioxidant metallothionein may reconcile short-term nicotine exposure

  1. Intrinsic increase in lymphangion muscle contractility in response to elevated afterload

    PubMed Central

    Scallan, Joshua P.; Wolpers, John H.; Muthuchamy, Mariappan; Gashev, Anatoliy A.; Zawieja, David C.

    2012-01-01

    Collecting lymphatic vessels share functional and biochemical characteristics with cardiac muscle; thus, we hypothesized that the lymphatic vessel pump would exhibit behavior analogous to homeometric regulation of the cardiac pump in its adaptation to elevated afterload, i.e., an increase in contractility. Single lymphangions containing two valves were isolated from the rat mesenteric microcirculation, cannulated, and pressurized for in vitro study. Pressures at either end of the lymphangion [input pressure (Pin), preload; output pressure (Pout), afterload] were set by a servo controller. Intralymphangion pressure (PL) was measured using a servo-null micropipette while internal diameter and valve positions were monitored using video methods. The responses to step- and ramp-wise increases in Pout (at low, constant Pin) were determined. PL and diameter data recorded during single contraction cycles were used to generate pressure-volume (P-V) relationships for the subsequent analysis of lymphangion pump behavior. Ramp-wise Pout elevation led to progressive vessel constriction, a rise in end-systolic diameter, and an increase in contraction frequency. Step-wise Pout elevation produced initial vessel distention followed by time-dependent declines in end-systolic and end-diastolic diameters. Significantly, a 30% leftward shift in the end-systolic P-V relationship accompanied an 84% increase in dP/dt after a step increase in Pout, consistent with an increase in contractility. Calculations of stroke work from the P-V loop area revealed that robust pumps produced net positive work to expel fluid throughout the entire afterload range, whereas weaker pumps exhibited progressively more negative work as gradual afterload elevation led to pump failure. We conclude that lymphatic muscle adapts to output pressure elevation with an intrinsic increase in contractility and that this compensatory mechanism facilitates the maintenance of lymph pump output in the face of edemagenic and

  2. Improvement of tactile roughness discrimination acuity correlates with perception of improved hand function in patients after hand surgery

    PubMed Central

    Fujimoto, Shuhei; Kon, Noriko

    2016-01-01

    [Purpose] The purpose of this study was to elucidate how well patients’ perceptions related to the improvements in their hand function during hospitalization. [Subjects] Sixteen patients who were hospitalized after hand surgery. [Methods] Using the Japanese Society for Surgery of the Hand edition of the Quick-Disabilities of the Arm, Shoulder, and Hand questionnaire; tactile roughness discrimination acuity, motor imagery, motor function, sensory function, and pain of the upper limb were assessed at admission and discharge. Spearman’s rank-order correlation coefficients were calculated using the differences in all assessment items at admission and discharge. A multiple regression analysis (stepwise method) was performed to investigate factors that correlated with improvements in Quick-Disabilities of the Arm, Shoulder, and Hand scores. [Results] The improvement of tactile roughness discrimination acuity was significantly associated with patient perception of improved hand function. [Conclusion] The results suggest that an improvement in tactile roughness discrimination acuity was most strongly correlated with patient perception of improved hand function. PMID:27190473

  3. Improvement of tactile roughness discrimination acuity correlates with perception of improved hand function in patients after hand surgery.

    PubMed

    Fujimoto, Shuhei; Kon, Noriko

    2016-04-01

    [Purpose] The purpose of this study was to elucidate how well patients' perceptions related to the improvements in their hand function during hospitalization. [Subjects] Sixteen patients who were hospitalized after hand surgery. [Methods] Using the Japanese Society for Surgery of the Hand edition of the Quick-Disabilities of the Arm, Shoulder, and Hand questionnaire; tactile roughness discrimination acuity, motor imagery, motor function, sensory function, and pain of the upper limb were assessed at admission and discharge. Spearman's rank-order correlation coefficients were calculated using the differences in all assessment items at admission and discharge. A multiple regression analysis (stepwise method) was performed to investigate factors that correlated with improvements in Quick-Disabilities of the Arm, Shoulder, and Hand scores. [Results] The improvement of tactile roughness discrimination acuity was significantly associated with patient perception of improved hand function. [Conclusion] The results suggest that an improvement in tactile roughness discrimination acuity was most strongly correlated with patient perception of improved hand function. PMID:27190473

  4. Improved effect of Pycnogenol on impaired spatial memory function in partial androgen deficiency rat model.

    PubMed

    Hasegawa, Noboru; Mochizuki, Miyako

    2009-06-01

    The improved effect of Pycnogenol on impaired spatial memory function was studied in orchidectomized rats. Endogenous testosterone levels were decreased by approximately one-half for 3 months after castration. In the radial arm maze, castration significantly impaired working and reference memory function without lowering motor function. Pycnogenol increased the NGF content in the hippocampus and cortex, and improved the spatial memory impairment. These observations confirmed that diagnostic accuracy can be improved by Pycnogenol in androgen-deficient rats. PMID:19142987

  5. Physiological contractility of cardiomyocytes in the wall of mouse and rat azygos vein

    PubMed Central

    Liu, Rong; Feng, Han-Zhong

    2014-01-01

    We recently demonstrated the abundant presence of cardiomyocytes in the wall of thoracic veins of adult mouse and rat. The highly differentiated morphology and myofilament protein contents of the venous cardiomyocytes suggested contractile functions. Here we further investigated the contractility of mouse and rat azygos venous rings compared with that of atrial strips and ventricular papillary muscle. 5-Bromo-4-chloro-indolyl-galactopyranoside (X-gal) staining of transgenic mouse vessels expressing lacZ under a cloned cardiac troponin T promoter demonstrated that the venous cardiomyocytes are discontinuous from atrial myocardium and aligned in the wall of thoracic veins perpendicular to the vessel axis. Histological sections displayed sarcomeric striations in the venous cardiomyocytes, which indicate an encirclement orientation of myofibrils in the vessel wall. Mechanical studies found that the rings of mouse and rat azygos vein produce strong cardiac type twitch contractions when stimulated with electrical pacing in contrast to the weak and slow smooth muscle contractions induced using 90 mM KCl. The twitch contraction and relaxation of mouse azygos veins further exhibited a cardiac type of β-adrenergic responses. Quantitative comparison showed that the contractions of venous cardiomyocytes are slightly slower than those of atrium muscle but significantly faster than those of ventricular papillary muscle. These novel findings indicate that the cardiomyocytes abundant in the wall of rodent thoracic veins possess fully differentiated cardiac muscle phenotype despite their anatomical and functional segregations from the heart. PMID:24477237

  6. Effects of Substrate Mechanics on Contractility of Cardiomyocytes Generated from Human Pluripotent Stem Cells

    PubMed Central

    Hazeltine, Laurie B.; Simmons, Chelsey S.; Salick, Max R.; Lian, Xiaojun; Badur, Mehmet G.; Han, Wenqing; Delgado, Stephanie M.; Wakatsuki, Tetsuro; Crone, Wendy C.; Pruitt, Beth L.; Palecek, Sean P.

    2012-01-01

    Human pluripotent stem cell (hPSC-) derived cardiomyocytes have potential applications in drug discovery, toxicity testing, developmental studies, and regenerative medicine. Before these cells can be reliably utilized, characterization of their functionality is required to establish their similarity to native cardiomyocytes. We tracked fluorescent beads embedded in 4.4–99.7 kPa polyacrylamide hydrogels beneath contracting neonatal rat cardiomyocytes and cardiomyocytes generated from hPSCs via growth-factor-induced directed differentiation to measure contractile output in response to changes in substrate mechanics. Contraction stress was determined using traction force microscopy, and morphology was characterized by immunocytochemistry for α-actinin and subsequent image analysis. We found that contraction stress of all types of cardiomyocytes increased with substrate stiffness. This effect was not linked to beating rate or morphology. We demonstrated that hPSC-derived cardiomyocyte contractility responded appropriately to isoprenaline and remained stable in culture over a period of 2 months. This study demonstrates that hPSC-derived cardiomyocytes have appropriate functional responses to substrate stiffness and to a pharmaceutical agent, which motivates their use in further applications such as drug evaluation and cardiac therapies. PMID:22649451

  7. A stepwise procedure to test contractility and susceptibility to injury for the rodent quadriceps muscle

    PubMed Central

    Pratt, Stephen J.P.; Lovering, Richard M.

    2014-01-01

    In patients with muscle injury or muscle disease, assessment of muscle damage is typically limited to clinical signs, such as tenderness, strength, range of motion, and more recently, imaging studies. Biological markers can also be used in measuring muscle injury, such as increased creatine kinase levels in the blood, but these are not always correlated with loss in muscle function (i.e. loss of force production). This is even true of histological findings from animals, which provide a “direct measure” of damage, but do not account for loss of function. The most comprehensive measure of the overall health of the muscle is contractile force. To date, animal models testing contractile force have been limited to the muscle groups moving the ankle. Here we describe an in vivo animal model for the quadriceps, with abilities to measure torque, produce a reliable muscle injury, and follow muscle recovery within the same animal over time. We also describe a second model used for direct measurement of force from an isolated quadriceps muscle in situ. PMID:25530979

  8. Algisyl-LVR™ with coronary artery bypass grafting reduces left ventricular wall stress and improves function in the failing human heart☆,☆☆

    PubMed Central

    Lee, Lik Chuan; Wall, Samuel T.; Klepach, Doron; Ge, Liang; Zhang, Zhihong; Lee, Randall J.; Hinson, Andy; Gorman, Joseph H.; Gorman, Robert C.; Guccione, Julius M.

    2013-01-01

    Background Left ventricular (LV) wall stress reduction is a cornerstone in treating heart failure. Large animal models and computer simulations indicate that adding non-contractile material to the damaged LV wall can potentially reduce myofiber stress. We sought to quantify the effects of a novel implantable hydrogel (Algisyl-LVR™) treatment in combination with coronary artery bypass grafting (i.e. Algisyl-LVR™+CABG) on both LV function and wall stress in heart failure patients. Methods and results Magnetic resonance images obtained before treatment (n=3), and at 3 months (n=3) and 6 months (n=2) afterwards were used to reconstruct the LV geometry. Cardiac function was quantified using end-diastolic volume (EDV), end-systolic volume (ESV), regional wall thickness, sphericity index and regional myofiber stress computed using validated mathematical modeling. The LV became more ellipsoidal after treatment, and both EDV and ESV decreased substantially 3 months after treatment in all patients; EDV decreased from 264±91 ml to 146±86 ml and ESV decreased from 184±85 ml to 86±76 ml. Ejection fraction increased from 32±8% to 47±18% during that period. Volumetric-averaged wall thickness increased in all patients, from 1.06±0.21 cm (baseline) to 1.3±0.26 cm (3 months). These changes were accompanied by about a 35% decrease in myofiber stress at end-of-diastole and at end-of-systole. Post-treatment myofiber stress became more uniform in the LV. Conclusions These results support the novel concept that Algisyl-LVR™+CABG treatment leads to decreased myofiber stress, restored LV geometry and improved function. PMID:23394895

  9. Application of retinoic acid improves form and function of tissue engineered corneal construct

    PubMed Central

    Abidin, Fadhilah Z; Gouveia, Ricardo M; Connon, Che J

    2015-01-01

    ABSTRACT Retinoic acid has recently been shown to control the phenotype and extracellular matrix composition of corneal stromal cells cultured in vitro as monolayers. This study set out to investigate the effects of retinoic acid on human corneal keratocytes within a 3D environment. Human corneal keratocytes were encapsulated in collagen gels, which were subsequently compressed under load, and cultured in serum-free media supplemented with 10 µM retinoic acid or DMSO vehicle for 30 days. Cell proliferation was quantified on selected days, while the expression of several important keratocytes markers was evaluated at day 30 using RT-PCR and immunoblotting. The weight and size of the collagen constructs were measured before and after hydration and contraction analyses. Retinoic acid enhanced keratocyte proliferation until day 30, whereas cells in control culture conditions showed reduced numbers after day 21. Both gene and protein expressions of keratocyte-characteristic proteoglycans (keratocan, lumican and decorin), corneal crystallins and collagen type I and V were significantly increased following retinoic acid supplementation. Retinoic acid also significantly reduced the expression of matrix metalloproteases 1, 3 and 9 while not increasing α-smooth muscle actin and fibronectin expression. Furthermore, these effects were also correlated with the ability of retinoic acid to significantly inhibit the contractility of keratocytes while allowing the build-up of corneal stromal extracellular matrix within the 3D constructs. Thus, retinoic acid supplementation represents a promising strategy to improve the phenotype of 3D-cultured keratocytes, and their usefulness as a model of corneal stroma for corneal biology and regenerative medicine applications. PMID:26496651

  10. Application of retinoic acid improves form and function of tissue engineered corneal construct.

    PubMed

    Abidin, Fadhilah Z; Gouveia, Ricardo M; Connon, Che J

    2015-01-01

    Retinoic acid has recently been shown to control the phenotype and extracellular matrix composition of corneal stromal cells cultured in vitro as monolayers. This study set out to investigate the effects of retinoic acid on human corneal keratocytes within a 3D environment. Human corneal keratocytes were encapsulated in collagen gels, which were subsequently compressed under load, and cultured in serum-free media supplemented with 10 µM retinoic acid or DMSO vehicle for 30 days. Cell proliferation was quantified on selected days, while the expression of several important keratocytes markers was evaluated at day 30 using RT-PCR and immunoblotting. The weight and size of the collagen constructs were measured before and after hydration and contraction analyses. Retinoic acid enhanced keratocyte proliferation until day 30, whereas cells in control culture conditions showed reduced numbers after day 21. Both gene and protein expressions of keratocyte-characteristic proteoglycans (keratocan, lumican and decorin), corneal crystallins and collagen type I and V were significantly increased following retinoic acid supplementation. Retinoic acid also significantly reduced the expression of matrix metalloproteases 1, 3 and 9 while not increasing α-smooth muscle actin and fibronectin expression. Furthermore, these effects were also correlated with the ability of retinoic acid to significantly inhibit the contractility of keratocytes while allowing the build-up of corneal stromal extracellular matrix within the 3D constructs. Thus, retinoic acid supplementation represents a promising strategy to improve the phenotype of 3D-cultured keratocytes, and their usefulness as a model of corneal stroma for corneal biology and regenerative medicine applications. PMID:26496651

  11. Prohibitin overexpression improves myocardial function in diabetic cardiomyopathy.

    PubMed

    Dong, Wen-Qian; Chao, Min; Lu, Qing-Hua; Chai, Wei-Li; Zhang, Wei; Chen, Xue-Ying; Liang, Er-Shun; Wang, Ling-Bo; Tian, Hong-Liang; Chen, Yu-Guo; Zhang, Ming-Xiang

    2016-01-01

    Prohibitin (PHB) is a highly conserved protein implicated in various cellular functions including proliferation, apoptosis, tumor suppression, transcription, and mitochondrial protein folding. However, its function in diabetic cardiomyopathy (DCM) is still unclear. In vivo, type 2 diabetic rat model was induced by using a high-fat diet and low-dose streptozotocin. Overexpression of the PHB protein in the model rats was achieved by injecting lentivirus carrying PHB cDNA via the jugular vein. Characteristics of type 2 DCM were evaluated by metabolic tests, echocardiography and histopathology. Rats with DCM showed severe insulin resistance, left ventricular dysfunction, fibrosis and apoptosis. PHB overexpression ameliorated the disease. Cardiofibroblasts (CFs) and H9c2 cardiomyoblasts were used in vitro to investigate the mechanism of PHB in altered function. In CFs treated with HG, PHB overexpression decreased expression of collagen, matrix metalloproteinase activity, and proliferation. In H9c2 cardiomyoblasts, PHB overexpression inhibited apoptosis induced by HG. Furthermore, the increased phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 was significantly decreased and the inhibited phosphorylation of Akt was restored in DCM. Therefore, PHB may be a new therapeutic target for human DCM. PMID:26623724

  12. Prohibitin overexpression improves myocardial function in diabetic cardiomyopathy

    PubMed Central

    Dong, Wen-qian; Chao, Min; Lu, Qing-hua; Chai, Wei-li; Zhang, Wei; Chen, Xue-ying; Liang, Er-shun; Wang, Ling-bo; Tian, Hong-liang; Chen, Yu-guo; Zhang, Ming-xiang

    2016-01-01

    Prohibitin (PHB) is a highly conserved protein implicated in various cellular functions including proliferation, apoptosis, tumor suppression, transcription, and mitochondrial protein folding. However, its function in diabetic cardiomyopathy (DCM) is still unclear. In vivo, type 2 diabetic rat model was induced by using a high-fat diet and low-dose streptozotocin. Overexpression of the PHB protein in the model rats was achieved by injecting lentivirus carrying PHB cDNA via the jugular vein. Characteristics of type 2 DCM were evaluated by metabolic tests, echocardiography and histopathology. Rats with DCM showed severe insulin resistance, left ventricular dysfunction, fibrosis and apoptosis. PHB overexpression ameliorated the disease. Cardiofibroblasts (CFs) and H9c2 cardiomyoblasts were used in vitro to investigate the mechanism of PHB in altered function. In CFs treated with HG, PHB overexpression decreased expression of collagen, matrix metalloproteinase activity, and proliferation. In H9c2 cardiomyoblasts, PHB overexpression inhibited apoptosis induced by HG. Furthermore, the increased phosphorylation of extracellular signal–regulated kinase (ERK) 1/2 was significantly decreased and the inhibited phosphorylation of Akt was restored in DCM. Therefore, PHB may be a new therapeutic target for human DCM. PMID:26623724

  13. Drainin required for membrane fusion of the contractile vacuole in Dictyostelium is the prototype of a protein family also represented in man.

    PubMed Central

    Becker, M; Matzner, M; Gerisch, G

    1999-01-01

    The contractile vacuole expels water by forming a channel with the plasma membrane and thus enables cells to survive in a hypo-osmotic environment. Here we characterize drainin, a Dictyostelium protein involved in this process, as the first member of a protein family represented in fission yeast, Caenorhabditis elegans and man. Gene replacement in Dictyostelium shows that drainin acts at a checkpoint of channel formation between the contractile vacuole and the plasma membrane. A green fluorescent protein fusion of drainin localizes specifically to the contractile vacuole and rescues its periodic discharge in drainin-null cells. Drainin is a peripheral membrane protein, requiring a short hydrophobic stretch in its C-terminal region for localization and function. We suggest that drainin acts in a signaling cascade that couples a volume-sensing device in the vacuolar membrane to the membrane fusion machinery. PMID:10369671

  14. PDE3A Regulates Basal Myocardial Contractility through Interacting with SERCA2a-Signaling Complexes in Mouse Heart

    PubMed Central

    Beca, Sanja; Ahmad, Faiyaz; Shen, Weixing; Liu, Jie; Makary, Samy; Polidovitch, Nazari; Sun, Junhui; Hockman, Steven; Chung, Youn Wook; Movesian, Matthew; Murphy, Elizabeth; Manganiello, Vincent; Backx, Peter H.

    2013-01-01

    Rationale cAMP is an important regulator of myocardial function, and regulation of cAMP hydrolysis by cyclic nucleotide phosphodiesterases (PDEs) is a critical determinant of the amplitude, duration, and compartmentation of cAMP–mediated signaling. The role of different PDE isozymes, particularly PDE3A versus PDE3B, in the regulation of heart function remains unclear. Objective To determine the relative contribution of PDE3A versus PDE3B isozymes in the regulation of heart function and to dissect the molecular basis for this regulation. Methods and Results Compared to wild-type (WT) littermates, cardiac contractility and relaxation were enhanced in isolated hearts from PDE3A−/−, but not PDE3B−/−, mice. Furthermore, PDE3 inhibition had no effect on PDE3A−/− hearts but increased contractility in WT (as expected) and PDE3B−/− hearts to levels indistinguishable from PDE3A−/−. The enhanced contractility in PDE3A−/− hearts was associated with cAMP-dependent elevations in Ca2+ transient amplitudes and increased SR Ca2+ content, without changes in L-type Ca2+ currents (ICa,L) of cardiomyocytes, as well as with increased SR Ca2+-ATPase (SERCA2a) activity, SR Ca2+ uptake rates, and phospholamban (PLN) phosphorylation in SR fractions. Consistent with these observations, PDE3 activity was reduced ~8-fold in SR fractions from PDE3A−/− hearts. Co-immunoprecipitation experiments further revealed that PDE3A associates with both SERCA2a and PLN in a complex which also contains AKAP-18, PKA-RII and PP2A. Conclusion Our data support the conclusion that PDE3A is the primary PDE3 isozyme modulating basal contractility and SR Ca2+ content by regulating cAMP in microdomains containing macromolecular complexes of SERCA2a-PLN-PDE3A. PMID:23168336

  15. Myocardial contractility in the stress echo lab: from pathophysiological toy to clinical tool.

    PubMed

    Bombardini, Tonino; Zoppè, Monica; Ciampi, Quirino; Cortigiani, Lauro; Agricola, Eustachio; Salvadori, Stefano; Loni, Tiziana; Pratali, Lorenza; Picano, Eugenio

    2013-01-01

    Up-regulation of Ca2+ entry through Ca2+ channels by high rates of beating is involved in the frequency-dependent regulation of contractility: this process is crucial in adaptation to exercise and stress and is universally known as force-frequency relation (FFR). Disturbances in calcium handling play a central role in the disturbed contractile function in myocardial failure. Measurements of twitch tension in isolated left-ventricular strips from explanted cardiomyopathic hearts compared with non-failing hearts show flat or biphasic FFR, while it is up-sloping in normal hearts. Starting in 2003 we introduced the FFR measurement in the stress echo lab using the end-systolic pressure (ESP)/End-systolic volume index (ESVi) ratio (the Suga index) at increasing heart rates. We studied a total of 2,031 patients reported in peer-reviewed journals: 483 during exercise, 34 with pacing, 850 with dobutamine and 664 during dipyridamole stress echo. We demonstrated the feasibility of FFR in the stress echo lab, the clinical usefulness of FFR for diagnosing latent contractile dysfunction in apparently normal hearts, and residual contractile reserve in dilated idiopathic and ischemic cardiomyopathy. In 400 patients with left ventricular dysfunction (ejection fraction 30 ± 9%) with negative stress echocardiography results, event-free survival was higher (p < 0.001) in patients with ΔESPVR (the difference between peak and rest end-systolic pressure-volume ratio, ESPVR) ≥ 0.4 mmHg/mL/m2. The prognostic stratification of patients was better with FFR, beyond the standard LV ejection fraction evaluation, also in the particular settings of severe mitral regurgitation or diabetics without stress-induced ischemia. In the particular setting of selection of heart transplant donors, the stress echo FFR was able to correctly select 34 marginal donor hearts efficiently transplanted in emergency recipients. Starting in 2007, we introduced an operator-independent cutaneous sensor

  16. R4496C RyR2 mutation impairs atrial and ventricular contractility

    PubMed Central

    Coppini, Raffaele; Scellini, Beatrice; Ferrara, Claudia; Pioner, Josè Manuel; Mazzoni, Luca; Priori, Silvia; Cerbai, Elisabetta; Tesi, Chiara; Poggesi, Corrado

    2016-01-01

    Ryanodine receptor (RyR2) is the major Ca2+ channel of the cardiac sarcoplasmic reticulum (SR) and plays a crucial role in the generation of myocardial force. Changes in RyR2 gating properties and resulting increases in its open probability (Po) are associated with Ca2+ leakage from the SR and arrhythmias; however, the effects of RyR2 dysfunction on myocardial contractility are unknown. Here, we investigated the possibility that a RyR2 mutation associated with catecholaminergic polymorphic ventricular tachycardia, R4496C, affects the contractile function of atrial and ventricular myocardium. We measured isometric twitch tension in left ventricular and atrial trabeculae from wild-type mice and heterozygous transgenic mice carrying the R4496C RyR2 mutation and found that twitch force was comparable under baseline conditions (30°C, 2 mM [Ca2+]o, 1 Hz). However, the positive inotropic responses to high stimulation frequency, 0.1 µM isoproterenol, and 5 mM [Ca2+]o were decreased in R4496C trabeculae, as was post-rest potentiation. We investigated the mechanisms underlying inotropic insufficiency in R4496C muscles in single ventricular myocytes. Under baseline conditions, the amplitude of the Ca2+ transient was normal, despite the reduced SR Ca2+ content. Under inotropic challenge, however, R4496C myocytes were unable to boost the amplitude of Ca2+ transients because they are incapable of properly increasing the amount of Ca2+ stored in the SR because of a larger SR Ca2+ leakage. Recovery of force in response to premature stimuli was faster in R4496C myocardium, despite the unchanged rates of recovery of L-type Ca2+ channel current (ICa-L) and SR Ca2+ content in single myocytes. A faster recovery from inactivation of the mutant R4496C channels could explain this behavior. In conclusion, changes in RyR2 channel gating associated with the R4496C mutation could be directly responsible for the alterations in both ventricular and atrial contractility. The increased RyR2 Po

  17. The characteristics of intrinsic complex micro-contractile activity in isolated strips of the rat bladder.

    PubMed

    Gillespie, J I; Rouget, C; Palea, S; Granato, C; Birder, L; Korstanje, C

    2015-07-01

    In the resting and un-stimulated state, the bladder wall is not quiescent and discrete contractile events, microcontractions, can be recorded in almost all species. This activity contributes to the active element of compliance and to the basal resting tension. This intrinsic activity underpins the more complex phasic activity, non-voiding activity (NVA) that can be seen to increase progressively as the bladder is filled. The NVA represents the motor component of a motor sensory system that relays information to the CNS on bladder volume. Despite the importance of this intrinsic motor activity, little is known about the mechanisms involved in its generation and modulation. The present experiments were done on isolated hemi-bladders from normal rats and measurements made of the intrinsic motor activity. Detailed analysis of the resting state reveals the presence of discrete phasic contractile events, micro-contractions that range in amplitude from 0.1-0.6 mN. These events seem to occur randomly and the basal activity has the appearance of ‘noise’. An analysis of the frequency amplitude distribution of the contractile events, reveals that the total activity appears to be the sum of a number of discrete contractile units, each generating a phasic contraction about a specific mean value and with characteristic frequency. In a hemi-bladder, there are between 20-30 units generating the activity at rest. Using the timed integral of the activity (product of amplitude and frequency), it was noted that the activity was increased by the muscarinic agonist carbachol, but it was decreased by the β-adrenergic agonist isoprenaline. Stretching the preparations also increased the activity. Using these observations, a simple model of the structural and functional organisation of the isolated rat bladder is proposed: the wall appears to be arranged into a number of discrete motor units acting independently. However, the activity can be stimulated or inhibited by pharmacological

  18. Tetrahydrobiopterin Improves Endothelial Function in Cardiovascular Disease: A Systematic Review

    PubMed Central

    Wang, Qiongying; Yang, Mina; Xu, Han; Yu, Jing

    2014-01-01

    Background. Tetrahydrobiopterin (BH4) is a cofactor of nitric oxide synthase (NOS). Nitric oxide (NO) bioavailability is reduced during the early stage of vascular diseases, such as coronary artery disease, hypercholesterolemia, hypertension, and diabetic vasculopathy, and even throughout the entire progression of atherosclerosis. Methods. A literature search was performed using electronic databases (up to January 31, 2014), including MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL), using an established strategy. Results. Fourteen articles were selected with a total of 370 patients. Ten of the fourteen studies showed a significant improvement in the endothelial dysfunction of various cardiovascular disease groups with BH4 supplementation compared with the control groups or placebos. Three studies showed no positive outcome, and one study showed that low-dose BH4 had no effect but that high-dose BH4 did have a significantly different result. Conclusions. This review concludes that supplementation with BH4 and/or augmentation of the endogenous levels of BH4 will be a novel approach to improve the endothelial dysfunction observed in various cardiovascular diseases. BH4 might be considered to be a new therapeutic agent to prevent the initiation and progression of cardiovascular disease. PMID:25548592

  19. Spontaneous Oscillations of Elastic Contractile Materials with Turnover

    NASA Astrophysics Data System (ADS)

    Dierkes, Kai; Sumi, Angughali; Solon, Jérôme; Salbreux, Guillaume

    2014-10-01

    Single and collective cellular oscillations driven by the actomyosin cytoskeleton have been observed in numerous biological systems. Here, we propose that these oscillations can be accounted for by a generic oscillator model of a material turning over and contracting against an elastic element. As an example, we show that during dorsal closure of the Drosophila embryo, experimentally observed changes in actomyosin concentration and oscillatory cell shape changes can, indeed, be captured by the dynamic equations studied here. We also investigate the collective dynamics of an ensemble of such contractile elements and show that the relative contribution of viscous and friction losses yields different regimes of collective oscillations. Taking into account the diffusion of force-producing molecules between contractile elements, our theoretical framework predicts the appearance of traveling waves, resembling the propagation of actomyosin waves observed during morphogenesis.

  20. An Optogenetic Method to Modulate Cell Contractility during Tissue Morphogenesis.

    PubMed

    Guglielmi, Giorgia; Barry, Joseph D; Huber, Wolfgang; De Renzis, Stefano

    2015-12-01

    Morphogenesis of multicellular organisms is driven by localized cell shape changes. How, and to what extent, changes in behavior in single cells or groups of cells influence neighboring cells and large-scale tissue remodeling remains an open question. Indeed, our understanding of multicellular dynamics is limited by the lack of methods allowing the modulation of cell behavior with high spatiotemporal precision. Here, we developed an optogenetic approach to achieve local modulation of cell contractility and used it to control morphogenetic movements during Drosophila embryogenesis. We show that local inhibition of apical constriction is sufficient to cause a global arrest of mesoderm invagination. By varying the spatial pattern of inhibition during invagination, we further demonstrate that coordinated contractile behavior responds to local tissue geometrical constraints. Together, these results show the efficacy of this optogenetic approach to dissect the interplay between cell-cell interaction, force transmission, and tissue geometry during complex morphogenetic processes. PMID:26777292

  1. Emergent Global Contractile Force in Cardiac Tissues.

    PubMed

    Knight, Meghan B; Drew, Nancy K; McCarthy, Linda A; Grosberg, Anna

    2016-04-12

    The heart is a complex organ whose structure and function are intricately linked at multiple length scales. Although several advancements have been achieved in the field of cardiac tissue engineering, current in vitro cardiac tissues do not fully replicate the structure or function necessary for effective cardiac therapy and cardiotoxicity studies. This is partially due to a deficiency in current understandings of cardiac tissue organization's potential downstream effects, such as changes in gene expression levels. We developed a novel (to our knowledge) in vitro tool that can be used to decouple and quantify the contribution of organization and associated downstream effects to tissue function. To do so, cardiac tissue monolayers were designed into a parquet pattern to be organized anisotropically on a local scale, within a parquet tile, and with any desired organization on a global scale. We hypothesized that if the downstream effects were muted, the relationship between developed force and tissue organization could be modeled as a sum of force vectors. With the in vitro experimental platforms of parquet tissues and heart-on-a-chip devices, we were able to prove this hypothesis for both systolic and diastolic stresses. Thus, insight was gained into the relationship between the generated stress and global myofibril organization. Furthermore, it was demonstrated that the developed quantitative tool could be used to estimate the changes in stress production due to downstream effects decoupled from tissue architecture. This has the potential to elucidate properties coupled to tissue architecture, which change force production and pumping function in the diseased heart or stem cell-derived tissues. PMID:27074686

  2. Hibiscus sabdariffa extract lowers blood pressure and improves endothelial function.

    PubMed

    Joven, Jorge; March, Isabel; Espinel, Eugenia; Fernández-Arroyo, Salvador; Rodríguez-Gallego, Esther; Aragonès, Gerard; Beltrán-Debón, Raúl; Alonso-Villaverde, Carlos; Rios, Lidia; Martin-Paredero, Vicente; Menendez, Javier A; Micol, Vicente; Segura-Carretero, Antonio; Camps, Jordi

    2014-06-01

    Polyphenols from Hibiscus sabdariffa calices were administered to patients with metabolic syndrome (125 mg/kg/day for 4 wk, n = 31) and spontaneously hypertensive rats (125 or 60 mg/kg in a single dose or daily for 1 wk, n = 8 for each experimental group). The H. sabdariffa extract improved metabolism, displayed potent anti-inflammatory and antioxidant activities, and significantly reduced blood pressure in both humans and rats. Diuresis and inhibition of the angiotensin I-converting enzyme were found to be less important mechanisms than those related to the antioxidant, anti-inflammatory, and endothelium-dependent effects to explain the beneficial actions. Notably, polyphenols induced a favorable endothelial response that should be considered in the management of metabolic cardiovascular risks. PMID:24668839

  3. Regular Football Practice Improves Autonomic Cardiac Function in Male Children

    PubMed Central

    Fernandes, Luis; Oliveira, Jose; Soares-Miranda, Luisa; Rebelo, Antonio; Brito, Joao

    2015-01-01

    Background: The role of the autonomic nervous system (ANS) in the cardiovascular regulation is of primal importance. Since it has been associated with adverse conditions such as cardiac arrhythmias, sudden death, sleep disorders, hypertension and obesity. Objectives: The present study aimed to investigate the impact of recreational football practice on the autonomic cardiac function of male children, as measured by heart rate variability. Patients and Methods: Forty-seven male children aged 9 - 12 years were selected according to their engagement with football oriented practice outside school context. The children were divided into a football group (FG; n = 22) and a control group (CG; n = 25). The FG had regular football practices, with 2 weekly training sessions and occasional weekend matches. The CG was not engaged with any physical activity other than complementary school-based physical education classes. Data from physical activity, physical fitness, and heart rate variability measured in time and frequency domains were obtained. Results: The anthropometric and body composition characteristics were similar in both groups (P > 0.05). The groups were also similar in time spent daily on moderate-to-vigorous physical activities (FG vs. CG: 114 ± 64 vs. 87 ± 55 minutes; P > 0.05). However, the FG performed better (P < 0.05) in Yo-Yo intermittent endurance test (1394 ± 558 vs. 778 ± 408 m) and 15-m sprint test (3.06 ± 0.17 vs. 3.20 ± 0.23 s). Also, the FG presented enhanced autonomic function. Significant differences were detected (P < 0.05) between groups for low frequency normalized units (38.0 ± 15.2 vs. 47.3 ± 14.2 n.u (normalized units)), high frequency normalized units (62.1 ± 15.2 vs. 52.8 ± 14.2 n.u.), and LF:HF ratio (0.7 ± 0.4 vs. 1.1 ± 0.6 ms2). Conclusions: Children engaged with regular football practice presented enhanced physical fitness and autonomic function, by increasing vagal tone at rest. PMID:26448848

  4. Improving Kepler Pipeline Sensitivity with Pixel Response Function Photometry.

    NASA Astrophysics Data System (ADS)

    Morris, Robert L.; Bryson, Steve; Jenkins, Jon Michael; Smith, Jeffrey C

    2014-06-01

    We present the results of our investigation into the feasibility and expected benefits of implementing PRF-fitting photometry in the Kepler Science Processing Pipeline. The Kepler Pixel Response Function (PRF) describes the expected system response to a point source at infinity and includes the effects of the optical point spread function, the CCD detector responsivity function, and spacecraft pointing jitter. Planet detection in the Kepler pipeline is currently based on simple aperture photometry (SAP), which is most effective when applied to uncrowded bright stars. Its effectiveness diminishes rapidly as target brightness decreases relative to the effects of noise sources such as detector electronics, background stars, and image motion. In contrast, PRF photometry is based on fitting an explicit model of image formation to the data and naturally accounts for image motion and contributions of background stars. The key to obtaining high-quality photometry from PRF fitting is a high-quality model of the system's PRF, while the key to efficiently processing the large number of Kepler targets is an accurate catalog and accurate mapping of celestial coordinates onto the focal plane. If the CCD coordinates of stellar centroids are known a priori then the problem of PRF fitting becomes linear. A model of the Kepler PRF was constructed at the time of spacecraft commissioning by fitting piecewise polynomial surfaces to data from dithered full frame images. While this model accurately captured the initial state of the system, the PRF has evolved dynamically since then and has been seen to deviate significantly from the initial (static) model. We construct a dynamic PRF model which is then used to recover photometry for all targets of interest. Both simulation tests and results from Kepler flight data demonstrate the effectiveness of our approach. Kepler was selected as the 10th mission of the Discovery Program. Funding for this mission is provided by NASA’s Science

  5. Multicellular contractility contributes to the emergence of mesothelioma nodules

    NASA Astrophysics Data System (ADS)

    Czirok, Andras

    Malignant pleural mesothelioma (MPM) nodules arise from the mesothelial lining of the pleural cavity by a poorly understood mechanism. We demonstrate that macroscopic multicellular aggregates, reminiscent of the MPM nodules found in patients, develop when MPM cell lines are cultured at high cell densities for several weeks. Surprisingly, the nodule-like aggregates do not arise by excessive local cell proliferation, but by myosin II-driven cell contractility. Contractile nodules contain prominent actin cables that can span several cells. Several features of the in vitro MPM nodule development can be explained by a computational model that assumes uniform and steady intercellular contractile forces within a monolayer of cells, and a mechanical load-dependent lifetime of cell-cell contacts. The model behaves as a self-tensioned Maxwell fluid and exhibits an instability that leads to pattern formation. Altogether, our findings suggest that inhibition of the actomyosin system may provide a hitherto not utilized therapeutic approach to affect MPM growth. NIH R01-GM102801.

  6. Collective cancer cell invasion induced by coordinated contractile stresses.

    PubMed

    Jimenez Valencia, Angela M; Wu, Pei-Hsun; Yogurtcu, Osman N; Rao, Pranay; DiGiacomo, Josh; Godet, Inês; He, Lijuan; Lee, Meng-Horng; Gilkes, Daniele; Sun, Sean X; Wirtz, Denis

    2015-12-22

    The physical underpinnings of fibrosarcoma cell dissemination from a tumor in a surrounding collagen-rich matrix are poorly understood. Here we show that a tumor spheroid embedded in a 3D collagen matrix exerts large contractile forces on the matrix before invasion. Cell invasion is accompanied by complex spatially and temporally dependent patterns of cell migration within and at the surface of the spheroids that are fundamentally different from migratory patterns of individual fibrosarcoma cells homogeneously distributed in the same type of matrix. Cells display a continuous transition from a round morphology at the spheroid core, to highly aligned elongated morphology at the spheroid periphery, which depends on both β1-integrin-based cell-matrix adhesion and myosin II/ROCK-based cell contractility. This isotropic-to-anisotropic transition corresponds to a shift in migration, from a slow and unpolarized movement at the core, to a fast, polarized and persistent one at the periphery. Our results also show that the ensuing collective invasion of fibrosarcoma cells is induced by anisotropic contractile stresses exerted on the surrounding matrix. PMID:26528856

  7. Alpha-Smooth Muscle Actin Expression Upregulates Fibroblast Contractile Activity

    PubMed Central

    Hinz, Boris; Celetta, Giuseppe; Tomasek, James J.; Gabbiani, Giulio; Chaponnier, Christine

    2001-01-01

    To evaluate whether α-smooth muscle actin (α-SMA) plays a role in fibroblast contractility, we first compared the contractile activity of rat subcutaneous fibroblasts (SCFs), expressing low levels of α-SMA, with that of lung fibroblasts (LFs), expressing high levels of α-SMA, with the use of silicone substrates of different stiffness degrees. On medium stiffness substrates the percentage of cells producing wrinkles was similar to that of α-SMA–positive cells in each fibroblast population. On high stiffness substrates, wrinkle production was limited to a subpopulation of LFs very positive for α-SMA. In a second approach, we measured the isotonic contraction of SCF- and LF-populated attached collagen lattices. SCFs exhibited 41% diameter reduction compared with 63% by LFs. TGFβ1 increased α-SMA expression and lattice contraction by SCFs to the levels of LFs; TGFβ-antagonizing agents reduced α-SMA expression and lattice contraction by LFs to the level of SCFs. Finally, 3T3 fibroblasts transiently or permanently transfected with α-SMA cDNA exhibited a significantly higher lattice contraction compared with wild-type 3T3 fibroblasts or to fibroblasts transfected with α-cardiac and β- or γ-cytoplasmic actin. This took place in the absence of any change in smooth muscle or nonmuscle myosin heavy-chain expression. Our results indicate that an increased α-SMA expression is sufficient to enhance fibroblast contractile activity. PMID:11553712

  8. Contractile dynamics change before morphological cues during florescence illumination

    PubMed Central

    Knoll, S. G.; Ahmed, W. W.; Saif, T. A.

    2015-01-01

    Illumination can have adverse effects on live cells. However, many experiments, e.g. traction force microscopy, rely on fluorescence microscopy. Current methods to assess undesired photo-induced cell changes rely on qualitative observation of changes in cell morphology. Here we utilize a quantitative technique to identify the effect of light on cell contractility prior to morphological changes. Fibroblasts were cultured on soft elastic hydrogels embedded with fluorescent beads. The adherent cells generated contractile forces that deform the substrate. Beads were used as fiducial markers to quantify the substrate deformation over time, which serves as a measure of cell force dynamics. We find that cells exposed to moderate fluorescence illumination (λ = 540–585 nm, I = 12.5 W/m2, duration = 60 s) exhibit rapid force relaxation. Strikingly, cells exhibit force relaxation after only 2 s of exposure, suggesting that photo-induced relaxation occurs nearly immediately. Evidence of photo-induced morphological changes were not observed for 15–30 min after illumination. Force relaxation and morphological changes were found to depend on wavelength and intensity of excitation light. This study demonstrates that changes in cell contractility reveal evidence of a photo-induced cell response long before any morphological cues. PMID:26691776

  9. Actomyosin contractility controls cell surface area of oligodendrocytes

    PubMed Central

    Kippert, Angelika; Fitzner, Dirk; Helenius, Jonne; Simons, Mikael

    2009-01-01

    Background To form myelin oligodendrocytes expa