Activation of p38 MAPK participates in brain ischemic tolerance induced by limb ischemic preconditioning by up-regulating HSP 70.

PubMed

Sun, Xiao-Cai; Xian, Xiao-Hui; Li, Wen-Bin; Li, Li; Yan, Cai-Zhen; Li, Qing-Jun; Zhang, Min

2010-08-01

This study investigates whether activation of p38 MAPK by the up-regulation of HSP 70 participates in the induction of brain ischemic tolerance by limb ischemic preconditioning (LIP). Western blot and immunohistochemical assays indicated that p38 MAPK activation occurred earlier than HSP 70 induction in the CA1 region of the hippocampus after LIP. P-p38 MAPK expression was up-regulated at 6h and reached its peak 12h after LIP, while HSP 70 expression was not significantly increased until 1 day and peaked 2 days after LIP. Neuropathological evaluation by thionin staining showed that quercetin (4 ml/kg, 50mg/kg, intraperitoneal injection), an inhibitor of HSP 70, blocked the protective effect of LIP against delayed neuronal death that is normally induced by lethal brain ischemic insult, indicating that HSP 70 participates in the induction of brain ischemic tolerance by LIP. Furthermore, SB 203580, an inhibitor of HSP 70, inhibited HSP 70 activation in the CA1 region of the hippocampus induced by LIP either with or without the presence of subsequent brain ischemic insult. Based on the above results, it can be concluded that activation of p38 MAPK participates in the brain ischemic tolerance induced by LIP at least partly by the up-regulation of HSP 70 expression. (c) 2010 Elsevier Inc. All rights reserved.

TIGAR contributes to ischemic tolerance induced by cerebral preconditioning through scavenging of reactive oxygen species and inhibition of apoptosis

PubMed Central

Zhou, Jun-Hao; Zhang, Tong-Tong; Song, Dan-Dan; Xia, Yun-Fei; Qin, Zheng-Hong; Sheng, Rui

2016-01-01

Previous study showed that TIGAR (TP53-induced glycolysis and apoptosis regulator) protected ischemic brain injury via enhancing pentose phosphate pathway (PPP) flux and preserving mitochondria function. This study was aimed to study the role of TIGAR in cerebral preconditioning. The ischemic preconditioning (IPC) and isoflurane preconditioning (ISO) models were established in primary cultured cortical neurons and in mice. Both IPC and ISO increased TIGAR expression in cortical neurons. Preconditioning might upregulate TIGAR through SP1 transcription factor. Lentivirus mediated knockdown of TIGAR significantly abolished the ischemic tolerance induced by IPC and ISO. ISO also increased TIGAR in mouse cortex and hippocampus and alleviated subsequent brain ischemia-reperfusion injury, while the ischemic tolerance induced by ISO was eliminated with TIGAR knockdown in mouse brain. ISO increased the production of NADPH and glutathione (GSH), and scavenged reactive oxygen species (ROS), while TIGAR knockdown decreased GSH and NADPH production and increased the level of ROS. Supplementation of ROS scavenger NAC and PPP product NADPH effectively rescue the neuronal injury caused by TIGAR deficiency. Notably, TIGAR knockdown inhibited ISO-induced anti-apoptotic effects in cortical neurons. These results suggest that TIGAR participates in the cerebral preconditioning through reduction of ROS and subsequent cell apoptosis. PMID:27256465

[Effect of limb ischemic preconditioning on the expression of p38 MAPK and HSP 70 in CA3 and DG regions of the hippocampus of rats].

PubMed

Sun, Xiao-Cai; Li, Wen-Bin; Zhao, Li; Jia, Hui-Xian; Wang, Fang; Zhang, Min; Li, Shu-Qin

2013-01-01

To observe the expression of p38 MAPK and HSP 70 in CA3 and dentate gyrus (DG) regions of the hippocampus of rats induced by limb ischemic preconditioning (LIP). Ninety-six rats were randomly divided into sham and LIP groups. And the animals in the LIP group were further divided into LIP 6 h, LIP 12 h, LIP 1 d, LIP 2 d, LIP 3 d, LIP 4 d and LIP 5 d subgroups according to the time of reperfusion after LIP. Immunohistochemical staining and Western blot were used to observe the expression of p38 MAPK and HSP 70 in CA3 and DG regions of the hippocampus. The results of the immunohistochemical staining and Western blot were consistent, which indicated that there were fluctuation in the p-p38 MAPK and HSP 70 expression in CA3 and DG regions after LIP compared with those of the sham group. The expression of p-p38 MAPK began to be up-regulated 1d after LIP and reached its peak at 3 d and lasted for 4 d after LIP. However, the expression of HSP 70 was significantly up-regulated 2 d after LIP compared to the sham group, reached its peak at 3 d and lasted until the 4 d after LIP. LIP up-regulates the expression of p38 MAPK and HSP 70 in the CA3 and DG regions of the hippocampus of rats.

Oxytocin Signaling in Basolateral and Central Amygdala Nuclei Differentially Regulates the Acquisition, Expression, and Extinction of Context-Conditioned Fear in Rats

ERIC Educational Resources Information Center

Campbell-Smith, Emma J.; Holmes, Nathan M.; Lingawi, Nura W.; Panayi, Marios C.; Westbrook, R. Frederick

2015-01-01

The present study investigated how oxytocin (OT) signaling in the central (CeA) and basolateral (BLA) amygdala affects acquisition, expression, and extinction of context-conditioned fear (freezing) in rats. In the first set of experiments, acquisition of fear to a shocked context was impaired by a preconditioning infusion of synthetic OT into the…

40 CFR 80.52 - Vehicle preconditioning.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 17 2013-07-01 2013-07-01 false Vehicle preconditioning. 80.52 Section...) REGULATION OF FUELS AND FUEL ADDITIVES Reformulated Gasoline § 80.52 Vehicle preconditioning. (a) Initial vehicle preconditioning and preconditioning between tests with different fuels shall be performed in...

40 CFR 80.52 - Vehicle preconditioning.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 16 2010-07-01 2010-07-01 false Vehicle preconditioning. 80.52 Section...) REGULATION OF FUELS AND FUEL ADDITIVES Reformulated Gasoline § 80.52 Vehicle preconditioning. (a) Initial vehicle preconditioning and preconditioning between tests with different fuels shall be performed in...

40 CFR 80.52 - Vehicle preconditioning.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 17 2014-07-01 2014-07-01 false Vehicle preconditioning. 80.52 Section...) REGULATION OF FUELS AND FUEL ADDITIVES Reformulated Gasoline § 80.52 Vehicle preconditioning. (a) Initial vehicle preconditioning and preconditioning between tests with different fuels shall be performed in...

40 CFR 80.52 - Vehicle preconditioning.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 17 2012-07-01 2012-07-01 false Vehicle preconditioning. 80.52 Section...) REGULATION OF FUELS AND FUEL ADDITIVES Reformulated Gasoline § 80.52 Vehicle preconditioning. (a) Initial vehicle preconditioning and preconditioning between tests with different fuels shall be performed in...

40 CFR 80.52 - Vehicle preconditioning.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 16 2011-07-01 2011-07-01 false Vehicle preconditioning. 80.52 Section...) REGULATION OF FUELS AND FUEL ADDITIVES Reformulated Gasoline § 80.52 Vehicle preconditioning. (a) Initial vehicle preconditioning and preconditioning between tests with different fuels shall be performed in...

Morphine Preconditioning Downregulates MicroRNA-134 Expression Against Oxygen-Glucose Deprivation Injuries in Cultured Neurons of Mice.

PubMed

Meng, Fanjun; Li, Yan; Chi, Wenying; Li, Junfa

2016-07-01

Brain protection by narcotics such as morphine is clinically relevant due to the extensive use of narcotics in the perioperative period. Morphine preconditioning induces neuroprotection in neurons, but it remains uncertain whether microRNA-134 (miR-134) is involved in morphine preconditioning against oxygen-glucose deprivation-induced injuries in primary cortical neurons of mice. The present study examined this issue. After cortical neurons of mice were cultured in vitro for 6 days, the neurons were transfected by respective virus vector, such as lentiviral vector (LV)-miR-control-GFP, LV-pre-miR-134-GFP, LV-pre-miR-134-inhibitor-GFP for 24 hours; after being normally cultured for 3 days again, morphine preconditioning was performed by incubating the transfected primary neurons with morphine (3 μM) for 1 hour, and then neuronal cells were exposed to oxygen-glucose deprivation (OGD) for 1 hour and oxygen-glucose recovery for 12 hours. The neuronal cells survival rate and the amount of apoptotic neurons were determined by MTT assay or TUNEL staining at designated time; and the expression levels of miR-134 were detected using real-time reverse transcription polymerase chain reaction at the same time. The neuronal cell survival rate was significantly higher, and the amount of apoptotic neurons was significantly decreased in neurons preconditioned with morphine before OGD than that of OGD alone. The neuroprotection induced by morphine preconditioning was partially blocked by upregulating miR-134 expression, and was enhanced by downregulating miR-134 expression. The expression of miR-134 was significantly decreased in morphine-preconditioned neurons alone without transfection. By downregulating miR-134 expression, morphine preconditioning protects primary cortical neurons of mice against injuries induced by OGD.

Chronic methamphetamine administration causes differential regulation of transcription factors in the rat midbrain.

PubMed

Krasnova, Irina N; Ladenheim, Bruce; Hodges, Amber B; Volkow, Nora D; Cadet, Jean Lud

2011-04-25

Methamphetamine (METH) is an addictive and neurotoxic psychostimulant widely abused in the USA and throughout the world. When administered in large doses, METH can cause depletion of striatal dopamine terminals, with preservation of midbrain dopaminergic neurons. Because alterations in the expression of transcription factors that regulate the development of dopaminergic neurons might be involved in protecting these neurons after toxic insults, we tested the possibility that their expression might be affected by toxic doses of METH in the adult brain. Male Sprague-Dawley rats pretreated with saline or increasing doses of METH were challenged with toxic doses of the drug and euthanized two weeks later. Animals that received toxic METH challenges showed decreases in dopamine levels and reductions in tyrosine hydroxylase protein concentration in the striatum. METH pretreatment protected against loss of striatal dopamine and tyrosine hydroxylase. In contrast, METH challenges caused decreases in dopamine transporters in both saline- and METH-pretreated animals. Interestingly, METH challenges elicited increases in dopamine transporter mRNA levels in the midbrain in the presence but not in the absence of METH pretreatment. Moreover, toxic METH doses caused decreases in the expression of the dopamine developmental factors, Shh, Lmx1b, and Nurr1, but not in the levels of Otx2 and Pitx3, in saline-pretreated rats. METH pretreatment followed by METH challenges also decreased Nurr1 but increased Otx2 and Pitx3 expression in the midbrain. These findings suggest that, in adult animals, toxic doses of METH can differentially influence the expression of transcription factors involved in the developmental regulation of dopamine neurons. The combined increases in Otx2 and Pitx3 expression after METH preconditioning might represent, in part, some of the mechanisms that served to protect against METH-induced striatal dopamine depletion observed after METH preconditioning.

Effects of hypoxic preconditioning on expression of transcription factor NGFI-A in the rat brain after unavoidable stress in the "learned helplessness" model.

PubMed

Baranova, K A; Rybnikova, E A; Mironova, V I; Samoilov, M O

2010-07-01

We report here our immunocytochemical studies establishing that the development of a depression-like state in rats following unavoidable stress in a "learned helplessness" model is accompanied by stable activation of the expression of transcription factor NGFI-A in the dorsal hippocampus (field CA1) and the magnocellular paraventricular nucleus of the hypothalamus, along with an early wave of post-stress expression, which died down rapidly, in the ventral hippocampus (the dentate gyrus) and a long period of up to five days of high-level expression in the neocortex. In rats subjected to three sessions of preconditioning consisting of moderate hypobaric hypoxia (360 mmHg, 2 h, with intervals of 24 h), which did not form depression in these circumstances, there were significant changes in the dynamics of immunoreactive protein content in the hippocampus, with a stable increase in expression in the ventral hippocampus and only transient and delayed (by five days) expression in field CA1. In the neocortex (layer II), preconditioning eliminated the effects of stress, preventing prolongation of the first wave of NGFI-A expression to five days, while in the magnocellular hypothalamus, conversely, preconditioning stimulated a second (delayed) wave of the expression of this transcription factor. The pattern of NGFI-A expression in the hippocampus, neocortex, and hypothalamus seen in non-preconditioned rats appears to reflect the pathological reaction to aversive stress, which, rather than adaptation, produced depressive disorders. Post-stress modification of the expression of the product of the early gene NGFI-A in the brain induced by hypoxic preconditioning probably plays an important role in increased tolerance to severe psychoemotional stresses and is an important component of antidepressant mechanisms.

Acetylation of histones in neocortex and hippocampus of rats exposed to different modes of hypobaric hypoxia: Implications for brain hypoxic injury and tolerance.

PubMed

Samoilov, Mikhail; Churilova, Anna; Gluschenko, Tatjana; Vetrovoy, Oleg; Dyuzhikova, Natalia; Rybnikova, Elena

2016-03-01

Acetylation of nucleosome histones results in relaxation of DNA and its availability for the transcriptional regulators, and is generally associated with the enhancement of gene expression. Although it is well known that activation of a variety of pro-adaptive genes represents a key event in the development of brain hypoxic/ischemic tolerance, the role of epigenetic mechanisms, in particular histone acetylation, in this process is still unexplored. The aim of the present study was to investigate changes in acetylation of histones in vulnerable brain neurons using original well-standardized model of hypobaric hypoxia and preconditioning-induced tolerance of the brain. Using quantitative immunohistochemistry and Western blot, effects of severe injurious hypobaric hypoxia (SH, 180mm Hg, 3h) and neuroprotective preconditioning mode (three episodes of 360mm Hg for 2h spaced at 24h) on the levels of the acetylated proteins and acetylated H3 Lys24 (H3K24ac) in the neocortex and hippocampus of rats were studied. SH caused global repression of the acetylation processes in the neocortex (layers II-III, V) and hippocampus (CA1, CA3) by 3-24h, and this effect was prevented by the preconditioning. Moreover, hypoxic preconditioning remarkably increased the acetylation of H3K24 in response to SH in the brain areas examined. The preconditioning hypoxia without subsequent SH also stimulated acetylation processes in the neocortex and hippocampus. The moderately enhanced expression of the acetylated proteins in the preconditioned rats was maintained for 24h, whereas acetylation of H3K24 was intense but transient, peaked at 3h. The novel data obtained in the present study indicate that large activation of the acetylation processes, in particular acetylation of histones might be essential for the development of brain hypoxic tolerance. Copyright © 2015 Elsevier GmbH. All rights reserved.

Preconditioning of bone marrow-derived mesenchymal stromal cells by tetramethylpyrazine enhances cell migration and improves functional recovery after focal cerebral ischemia in rats.

PubMed

Li, Lin; Chu, Lisheng; Fang, Yan; Yang, Yan; Qu, Tiebing; Zhang, Jianping; Yin, Yuanjun; Gu, Jingjing

2017-05-12

Transplantation of bone marrow-derived mesenchymal stem cells (BMSCs) is one of the new therapeutic strategies for treating ischemic stroke. However, the relatively poor migratory capacity of BMSCs toward infarcted regions limited the therapeutic potential of this approach. Pharmacological preconditioning can increase the expression of CXC chemokine receptor 4 (CXCR4) in BMSCs and enhance cell migration toward the injury site. In the present study, we investigated whether tetramethylpyrazine (TMP) preconditioning could enhance BMSCs migration to the ischemic brain and improve functional recovery through upregulating CXCR4 expression. BMSCs were identified by flow cytometry analysis. BMSCs migration was evaluated in vitro by transwell migration assay, and CXCR4 expression was measured by quantitative reverse transcription-polymerase chain reaction and western blot analysis. In rats with focal cerebral ischemia, the neurological function was evaluated by the modified neurological severity score, the adhesive removal test and the corner test. The homing BMSCs and angiogenesis were detected by immunofluorescence, and expression of stromal cell-derived factor-1 (SDF-1) and CXCR4 was measured by western blot analysis. Flow cytometry analysis demonstrated that BMSCs expressed CD29 and CD90, but not CD34 and CD45. TMP pretreatment dose-dependently induced BMSCs migration and CXCR4 expression in vitro, which was significantly inhibited by AMD3100, a CXCR4 antagonist. In rat stroke models, we found more TMP-preconditioned BMSCs homing toward the infarcted regions than nonpreconditioned cells, leading to improved neurological performance and enhanced angiogenesis. Moreover, TMP-preconditioned BMSCs significantly upregulated the protein expression of SDF-1 and CXCR4 in the ischemic boundary regions. These beneficial effects of TMP preconditioning were blocked by AMD3100. TMP preconditioning enhances the migration and homing ability of BMSCs, increases CXCR4 expression, promotes angiogenesis, and improves neurological performance. Therefore, TMP preconditioning may be an effective strategy to improve the therapeutic potency of BMSCs for ischemic stroke due to enhanced BMSCs migration to ischemic regions.

[Lessening effect of hypoxia-preconditioned rat cerebrospinal fluid on oxygen-glucose deprivation-induced injury of cultured hippocampal neurons in neonate rats and possible mechanism].

PubMed

Niu, Jing-Zhong; Zhang, Yan-Bo; Li, Mei-Yi; Liu, Li-Li

2011-12-25

The present study was to investigate the effect of cerebrospinal fluid (CSF) from the rats with hypoxic preconditioning (HPC) on apoptosis of cultured hippocampal neurons in neonate rats under oxygen glucose deprivation (OGD). Adult Wistar rats were exposed to 3 h of hypoxia for HPC, and then their CSF was taken out. Cultured hippocampal neurons from the neonate rats were randomly divided into four groups (n = 6): normal control group, OGD group, normal CSF group and HPC CSF group. OGD group received 1.5 h of incubation in glucose-free Earle's solution containing 1 mmol/L Na2S2O4, and normal and HPC CSF groups were subjected to 1 d of corresponding CSF treatments followed by 1.5 h OGD. The apoptosis of neurons was analyzed by confocal laser scanning microscope and flow cytometry using Annexin V/PI double staining. Moreover, protein expressions of Bcl-2 and Bax were detected by immunofluorescence. The results showed that few apoptotic cells were observed in normal control group, whereas the number of apoptotic cells was greatly increased in OGD group. Both normal and HPC CSF could decrease the apoptosis of cultured hippocampal neurons injured by OGD (P < 0.01). Notably, the protective effect of HPC CSF was stronger than that of normal one (P < 0.01). Compared to OGD group, normal and HPC CSF groups both showed significantly higher levels of Bcl-2 (P < 0.01), and Bcl-2 expression level in HPC CSF group was even higher than that in normal CSF group (P < 0.01). Whereas the expressions of Bax in normal and HPC CSF groups were significantly lower than that in OGD group (P < 0.01), and the Bax expression in HPC CSF group was even lower than that in normal CSF group (P < 0.01). These results suggest that CSF from hypoxic-preconditioned rats could degrade apoptotic rate of OGD-injured hippocampal neurons by up-regulating expression of Bcl-2 and down-regulating expression of Bax.

Coordinated Post-transcriptional Regulation of Hsp70.3 Gene Expression by MicroRNA and Alternative Polyadenylation*

PubMed Central

Tranter, Michael; Helsley, Robert N.; Paulding, Waltke R.; McGuinness, Michael; Brokamp, Cole; Haar, Lauren; Liu, Yong; Ren, Xiaoping; Jones, W. Keith

2011-01-01

Heat shock protein 70 (Hsp70) is well documented to possess general cytoprotective properties in protecting the cell against stressful and noxious stimuli. We have recently shown that expression of the stress-inducible Hsp70.3 gene in the myocardium in response to ischemic preconditioning is NF-κB-dependent and necessary for the resulting late phase cardioprotection against a subsequent ischemia/reperfusion injury. Here we show that the Hsp70.3 gene product is subject to post-transcriptional regulation through parallel regulatory processes involving microRNAs and alternative polyadenylation of the mRNA transcript. First, we show that cardiac ischemic preconditioning of the in vivo mouse heart results in decreased levels of two Hsp70.3-targeting microRNAs: miR-378* and miR-711. Furthermore, an ischemic or heat shock stimulus induces alternative polyadenylation of the expressed Hsp70.3 transcript that results in the accumulation of transcripts with a shortened 3′-UTR. This shortening of the 3′-UTR results in the loss of the binding site for the suppressive miR-378* and thus renders the alternatively polyadenylated transcript insusceptible to miR-378*-mediated suppression. Results also suggest that the alternative polyadenylation-mediated shortening of the Hsp70.3 3′-UTR relieves translational suppression observed in the long 3′-UTR variant, allowing for a more robust increase in protein expression. These results demonstrate alternative polyadenylation of Hsp70.3 in parallel with ischemic or heat shock-induced up-regulation of mRNA levels and implicate the importance of this process in post-transcriptional control of Hsp70.3 expression. PMID:21757701

Identification of Sleep-Modulated Pathways Involved in Neuroprotection from Stroke.

PubMed

Pace, Marta; Baracchi, Francesca; Gao, Bo; Bassetti, Claudio

2015-11-01

Sleep deprivation (SDp) performed before stroke induces an ischemic tolerance state as observed in other forms of preconditioning. As the mechanisms underlying this effect are not well understood, we used DNA oligonucleotide microarray analysis to identify the genes and the gene-pathways underlying SDp preconditioning effects. Gene expression was analyzed 3 days after stroke in 4 experimental groups: (i) SDp performed before focal cerebral ischemia (IS) induction; (ii) SDp performed before sham surgery; (iii) IS without SDp; and (iv) sham surgery without SDp. SDp was performed by gentle handling during the last 6 h of the light period, and ischemia was induced immediately after. Basic sleep research laboratory. Stroke induced a massive alteration in gene expression both in sleep deprived and non-sleep deprived animals. However, compared to animals that underwent ischemia alone, SDp induced a general reduction in transcriptional changes with a reduction in the upregulation of genes involved in cell cycle regulation and immune response. Moreover, an upregulation of a new neuroendocrine pathway which included melanin concentrating hormone, glycoprotein hormones-α-polypeptide and hypocretin was observed exclusively in rats sleep deprived before stroke. Our data indicate that sleep deprivation before stroke reprogrammed the signaling response to injury. The inhibition of cell cycle regulation and inflammation are neuroprotective mechanisms reported also for other forms of preconditioning treatment, whereas the implication of the neuroendocrine function is novel and has never been described before. These results therefore provide new insights into neuroprotective mechanisms involved in ischemic tolerance mechanisms. © 2015 Associated Professional Sleep Societies, LLC.

Remote Ischemic Preconditioning Enhances the Expression of Genes Encoding Antioxidant Enzymes and Endoplasmic Reticulum Stress-Related Proteins in Rat Skeletal Muscle.

PubMed

Park, Ui Jun; Kim, Hyoung Tae; Cho, Won Hyun; Park, Jae Hyoung; Jung, Hye Ra; Kim, Min Young

2016-12-01

Ischemic preconditioning (IPC), including remote IPC (rIPC) and direct IPC (dIPC), is a promising method to decrease ischemia-reperfusion (IR) injury. This study tested the effect of both rIPC and dIPC on the genes for antioxidant enzymes and endoplasmic reticulum (ER) stress-related proteins. Twenty rats were randomly divided into the control and study groups. In the control group (n=10), the right hind limb was sham-operated. The left hind limb (IscR) of the control group underwent IR injury without IPC. In the study group (n=10), the right hind limb received IR injury after 3 cycles of rIPC. The IscR received IR injury after 3 cycles of dIPC. Gene expression was analyzed by Quantitative real-time polymerase chain reaction from the anterior tibialis muscle. The expression of the antioxidant enzyme genes including glutathione peroxidase (GPx), superoxide dismutase (SOD) 1 and catalase (CAT) were significantly reduced in IscR compared with sham treatment. In comparison with IscR, rIPC enhanced the expression of GPx, SOD2, and CAT genes. dIPC enhanced the expression of SOD2 and CAT genes. The expression of SOD2 genes was consistently higher in rIPC than in dIPC, but the difference was only significant for SOD2. The expression of genes for ER stress-related proteins tended to be reduced in IscR in comparison with sham treatment. However, the difference was only significant for C/EBP homologous protein (CHOP). In comparison with IscR, rIPC significantly up-regulated activating transcription factor 4 and CHOP, whereas dIPC up-regulated CHOP. Both rIPC and dIPC enhanced expression of genes for antioxidant enzymes and ER stress-related proteins.

AMP-activated protein kinase (AMPK)-induced preconditioning in primary cortical neurons involves activation of MCL-1.

PubMed

Anilkumar, Ujval; Weisová, Petronela; Düssmann, Heiko; Concannon, Caoimhín G; König, Hans-Georg; Prehn, Jochen H M

2013-03-01

Neuronal preconditioning is a phenomenon where a previous exposure to a sub-lethal stress stimulus increases the resistance of neurons towards a second, normally lethal stress stimulus. Activation of the energy stress sensor, AMP-activated protein kinase (AMPK) has been shown to contribute to the protective effects of ischaemic and mitochondrial uncoupling-induced preconditioning in neurons, however, the molecular basis of AMPK-mediated preconditioning has been less well characterized. We investigated the effect of AMPK preconditioning using 5-aminoimidazole-4-carboxamide riboside (AICAR) in a model of NMDA-mediated excitotoxic injury in primary mouse cortical neurons. Activation of AMPK with low concentrations of AICAR (0.1 mM for 2 h) induced a transient increase in AMPK phosphorylation, protecting neurons against NMDA-induced excitotoxicity. Analysing potential targets of AMPK activation, demonstrated a marked increase in mRNA expression and protein levels of the anti-apoptotic BCL-2 family protein myeloid cell leukaemia sequence 1 (MCL-1) in AICAR-preconditioned neurons. Interestingly, over-expression of MCL-1 protected neurons against NMDA-induced excitotoxicity while MCL-1 gene silencing abolished the effect of AICAR preconditioning. Monitored intracellular Ca²⁺ levels during NMDA excitation revealed that MCL-1 over-expressing neurons exhibited improved bioenergetics and markedly reduced Ca²⁺ elevations, suggesting a potential mechanism through which MCL-1 confers neuroprotection. This study identifies MCL-1 as a key effector of AMPK-induced preconditioning in neurons. © 2012 International Society for Neurochemistry.

Preconditioned mesenchymal stem cells treat myasthenia gravis in a humanized preclinical model

PubMed Central

Sudres, Muriel; Maurer, Marie; Robinet, Marieke; Bismuth, Jacky; Truffault, Frédérique; Girard, Diane; Dragin, Nadine; Attia, Mohamed; Fadel, Elie; Santelmo, Nicola; Sicsic, Camille; Brenner, Talma

2017-01-01

Myasthenia gravis (MG) with anti–acetylcholine receptor (AChR) Abs is an autoimmune disease characterized by severe defects in immune regulation and thymic inflammation. Because mesenchymal stem cells (MSCs) display immunomodulatory features, we investigated whether and how in vitro–preconditioned human MSCs (cMSCs) could treat MG disease. We developed a new humanized preclinical model by subcutaneously grafting thymic MG fragments into immunodeficient NSG mice (NSG-MG model). Ninety percent of the animals displayed human anti-AChR Abs in the serum, and 50% of the animals displayed MG-like symptoms that correlated with the loss of AChR at the muscle endplates. Interestingly, each mouse experiment recapitulated the MG features of each patient. We next demonstrated that cMSCs markedly improved MG, reducing the level of anti-AChR Abs in the serum and restoring AChR expression at the muscle endplate. Resting MSCs had a smaller effect. Finally, we showed that the underlying mechanisms involved (a) the inhibition of cell proliferation, (b) the inhibition of B cell–related and costimulatory molecules, and (c) the activation of the complement regulator DAF/CD55. In conclusion, this study shows that a preconditioning step promotes the therapeutic effects of MSCs via combined mechanisms, making cMSCs a promising strategy for treating MG and potentially other autoimmune diseases. PMID:28405609

Mitochondria in the middle: exercise preconditioning protection of striated muscle

PubMed Central

Rodriguez, Dinah A.; Hord, Jeffrey M.

2016-01-01

Abstract Cellular and physiological adaptations to an atmosphere which became enriched in molecular oxygen spurred the development of a layered system of stress protection, including antioxidant and stress response proteins. At physiological levels reactive oxygen and nitrogen species regulate cell signalling as well as intracellular and intercellular communication. Exercise and physical activity confer a variety of stressors on skeletal muscle and the cardiovascular system: mechanical, metabolic, oxidative. Transient increases of stressors during acute bouts of exercise or exercise training stimulate enhancement of cellular stress protection against future insults of oxidative, metabolic and mechanical stressors that could induce injury or disease. This phenomenon has been termed both hormesis and exercise preconditioning (EPC). EPC stimulates transcription factors such as Nrf‐1 and heat shock factor‐1 and up‐regulates gene expression of a cadre of cytosolic (e.g. glutathione peroxidase and heat shock proteins) and mitochondrial adaptive or stress proteins (e.g. manganese superoxide dismutase, mitochondrial KATP channels and peroxisome proliferator activated receptor γ coactivator‐1 (PGC‐1)). Stress response and antioxidant enzyme inducibility with exercise lead to protection against striated muscle damage, oxidative stress and injury. EPC may indeed provide significant clinical protection against ischaemia–reperfusion injury, Type II diabetes and ageing. New molecular mechanisms of protection, such as δ‐opioid receptor regulation and mitophagy, reinforce the notion that mitochondrial adaptations (e.g. heat shock proteins, antioxidant enzymes and sirtuin‐1/PGC‐1 signalling) are central to the protective effects of exercise preconditioning. PMID:27060608

One- and three-time mild hypobaric hypoxia modifies expression of mitochondrial thioredoxin-2 in hippocampus of rat.

PubMed

Stroev, Sergey Alexandrovich; Tjulkova, Ekaterina Iosifovna; Samoilov, Michail Olegovich; Pelto-Huikko, Markku Tapio

2011-01-01

Our previous study demonstrated that preconditioning by 3-times repetitive mild hypoxia significantly augmented expression of mitochondrial thioredoxin-2 (Trx-2) at 3 h after subsequent acute severe hypoxia in rat hippocampus. However, it was unclear whether this augmentation was due to build up of Trx-2 by mild hypoxia before severe hypoxia or by modification of reaction to severe hypoxia itself. To answer on this question we study the expression level during and after preconditioning without subsequent severe hypoxia. Trx-2 expression was studied by immunocytochemistry 3 h and 24 h after first session and 3 h and 24 h after last session of 3-times (spaced at 24 h) mild hypobaric hypoxia (360 Torr, 2h). At 3 h after 1-time hypoxia (first session of 3-time hypoxia) the total number of Trx-2-immunoreactive cells (Nt) was significantly decreased in contrast with control in CA2, CA3 and DG. The number of cells with intensive expression of Trx-2 (Ni) was reduced in CA1 and CA3. At 24 h after the same 1-time hypoxia Nt was lower than in control and at 3 h time-point in all hippocampal areas studied (CA1, CA2, CA3 and DG); Ni was decreased only compared to control in CA1 and CA3. At 3 h after last session of 3-times hypoxia Nt and Ni were significantly down regulated in comparison with control only in CA1. At 24 h after it Nt was significantly decreased compared to control in CA1, CA2 and CA3 (in DG the decrease was not statistically significant) but in all areas was higher than at 24 h after 1-time hypoxia. Dynamics of Nt changes from 3-hours after single to 24-hours after triple moderate hypoxia had the wave phase character. These findings indicate that Trx-2 expression in most areas of hippocampus was decreased to 24 h after 3-time mild hypoxia. Thus the augmentation of Trx-2 expression in hippocampal neurons of preconditioned animals in response to subsequent severe hypoxia is caused obviously not by Trx-2 accumulation during preconditioning sessions but by modification of reaction to severe impact.

Ischemic preconditioning negatively regulates plenty of SH3s-mixed lineage kinase 3-Rac1 complex and c-Jun N-terminal kinase 3 signaling via activation of Akt.

PubMed

Zhang, Q-G; Han, D; Xu, J; Lv, Q; Wang, R; Yin, X-H; Xu, T-L; Zhang, G-Y

2006-12-01

Activation of Akt/protein kinase B has been recently reported to play an important role in ischemic tolerance. We here demonstrate that the decreased protein expression and phosphorylation of phosphatase and tensin homolog deleted from chromosome 10 (PTEN) underlie the increased Akt-Ser-473 phosphorylation in the hippocampal CA1 subfield in ischemic preconditioning (IPC). Co-immunoprecipitation analysis reveals that Akt physically interacts with Rac1, a small Rho family GTPase required for mixed lineage kinase 3 (MLK3) autophosphorylation, and both this interaction and Rac1-Ser-71 phosphorylation induced by Akt are promoted in preconditioned rats. In addition, we show that Akt activation results in the disassembly of the plenty of SH3s (POSH)-MLK3-Rac1 signaling complex and down-regulation of the activation of MLK3/c-Jun N-terminal kinase (JNK) pathway. Akt activation results in decreased serine phosphorylation of 14-3-3, a cytoplasmic anchor of Bax, and prevents ischemia-induced mitochondrial translocation of Bax, release of cytochrome c, and activation of caspase-3. The expression of Fas ligand is also decreased in the CA1 region. Akt activation protects against apoptotic neuronal death as shown in TUNEL staining following IPC. Intracerebral infusion of LY294002 before IPC reverses the increase in Akt phosphorylation and the decrease in JNK signaling activation, as well as the neuroprotective action of IPC. Our results suggest that activation of pro-apoptotic MLK3/JNK3 cascade can be suppressed through activating anti-apoptotic phosphoinositide 3-kinase/Akt pathway induced by a sublethal ischemic insult, which provides a functional link between Akt and the JNK family of stress-activated kinases in ischemic tolerance.

Endoplasmic reticulum stress preconditioning attenuates methylmercury-induced cellular damage by inducing favorable stress responses

PubMed Central

Usuki, Fusako; Fujimura, Masatake; Yamashita, Akio

2013-01-01

We demonstrate that methylmercury (MeHg)-susceptible cells preconditioned with an inhibitor of endoplasmic reticulum (ER) Ca2+-ATPase, thapsigargin, showed resistance to MeHg cytotoxicity through favorable stress responses, which included phosphorylation of eukaryotic initiation factor 2 alpha (Eif2α), accumulation of activating transcription factor 4 (Atf4), upregulation of stress-related proteins, and activation of extracellular signal regulated kinase pathway. In addition, ER stress preconditioning induced suppression of nonsense-mediated mRNA decay (NMD) mainly through the phospho-Eif2α-mediated general suppression of translation initiation and possible combined effects of decreased several NMD components expression. Atf4 accumulation was not mediated by NMD inhibition but translation inhibition of its upstream open reading frame (uORF) and translation facilitation of its protein-coding ORF by the phospho-Eif2α. These results suggested that ER stress plays an important role in MeHg cytotoxicity and that the modulation of ER stress has therapeutic potential to attenuate MeHg cytotoxicity, the underlying mechanism being the induction of integrated stress responses. PMID:23907635

Prospects for Creation of Cardioprotective Drugs Based on Cannabinoid Receptor Agonists.

PubMed

Maslov, Leonid N; Khaliulin, Igor; Zhang, Yi; Krylatov, Andrey V; Naryzhnaya, Natalia V; Mechoulam, Raphael; De Petrocellis, Luciano; Downey, James M

2016-05-01

Cannabinoids can mimic the infarct-reducing effect of early ischemic preconditioning, delayed ischemic preconditioning, and ischemic postconditioning against myocardial ischemia/reperfusion. They do this primarily through both CB1 and CB2 receptors. Cannabinoids are also involved in remote preconditioning of the heart. The cannabinoid receptor ligands also exhibit an antiapoptotic effect during ischemia/reperfusion of the heart. The acute cardioprotective effect of cannabinoids is mediated by activation of protein kinase C, extracellular signal-regulated kinase, and p38 kinase. The delayed cardioprotective effect of cannabinoid anandamide is mediated via stimulation of phosphatidylinositol-3-kinase-Akt signaling pathway and enhancement of heat shock protein 72 expression. The delayed cardioprotective effect of another cannabinoid, Δ9-tetrahydrocannabinol, is associated with augmentation of nitric oxide (NO) synthase expression, but data on the involvement of NO synthase in the acute cardioprotective effect of cannabinoids are contradictory. The adenosine triphosphate-sensitive K(+)channel is involved in the synthetic cannabinoid HU-210-induced cardiac resistance to ischemia/reperfusion injury. Cannabinoids inhibit Na(+)/Ca(2+)exchange via peripheral cannabinoid receptor (CB2) activation that may also be related to the antiapoptotic and cardioprotective effects of cannabinoids. The cannabinoid receptor agonists should be considered as prospective group of compounds for creation of drugs that are able to protect the heart against ischemia-reperfusion injury in the clinical setting. © The Author(s) 2015.

41 CFR 102-72.68 - What preconditions must be satisfied before an Executive agency may exercise the delegated...

Code of Federal Regulations, 2011 CFR

2011-01-01

... 41 Public Contracts and Property Management 3 2011-01-01 2011-01-01 false What preconditions must... ancillary repair and alteration project? 102-72.68 Section 102-72.68 Public Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION REAL...

41 CFR 102-72.68 - What preconditions must be satisfied before an Executive agency may exercise the delegated...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false What preconditions must... ancillary repair and alteration project? 102-72.68 Section 102-72.68 Public Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION REAL...

Regulated production of free radicals by the mitochondrial electron transport chain: Cardiac ischemic preconditioning.

PubMed

Matsuzaki, Satoshi; Szweda, Pamela A; Szweda, Luke I; Humphries, Kenneth M

2009-11-30

Excessive production of free radicals by mitochondria is associated with, and likely contributes to, the progression of numerous pathological conditions. Nevertheless, the production of free radicals by the mitochondria may have important biological functions under normal or stressed conditions by activating or modulating redox-sensitive cellular signaling pathways. This raises the intriguing possibility that regulated mitochondrial free radical production occurs via mechanisms that are distinct from pathologies associated with oxidative damage. Indeed, the capacity of mitochondria to produce free radicals in a limited manner may play a role in ischemic preconditioning, the phenomenon whereby short bouts of ischemia protect from subsequent prolonged ischemia and reperfusion. Ischemic preconditioning can thus serve as an important model system for defining regulatory mechanisms that allow for transient, signal-inducing, production of free radicals by mitochondria. Defining how these mechanism(s) occur will provide insight into therapeutic approaches that minimize oxidative damage without altering normal cellular redox biology. The aim of this review is to present and discuss evidence for the regulated production of superoxide by the electron transport chain within the ischemic preconditioning paradigm of redox regulation.

Preconditioning mesenchymal stem cells with the mood stabilizers lithium and valproic acid enhances therapeutic efficacy in a mouse model of Huntington's disease.

PubMed

Linares, Gabriel R; Chiu, Chi-Tso; Scheuing, Lisa; Leng, Yan; Liao, Hsiao-Mei; Maric, Dragan; Chuang, De-Maw

2016-07-01

Huntington's disease (HD) is a fatal neurodegenerative disorder caused by CAG repeat expansions in the huntingtin gene. Although, stem cell-based therapy has emerged as a potential treatment for neurodegenerative diseases, limitations remain, including optimizing delivery to the brain and donor cell loss after transplantation. One strategy to boost cell survival and efficacy is to precondition cells before transplantation. Because the neuroprotective actions of the mood stabilizers lithium and valproic acid (VPA) induce multiple pro-survival signaling pathways, we hypothesized that preconditioning bone marrow-derived mesenchymal stem cells (MSCs) with lithium and VPA prior to intranasal delivery to the brain would enhance their therapeutic efficacy, and thereby facilitate functional recovery in N171-82Q HD transgenic mice. MSCs were treated in the presence or absence of combined lithium and VPA, and were then delivered by brain-targeted single intranasal administration to eight-week old HD mice. Histological analysis confirmed the presence of MSCs in the brain. Open-field test revealed that ambulatory distance and mean velocity were significantly improved in HD mice that received preconditioned MSCs, compared to HD vehicle-control and HD mice transplanted with non-preconditioned MSCs. Greater benefits on motor function were observed in HD mice given preconditioned MSCs, while HD mice treated with non-preconditioned MSCs showed no functional benefits. Moreover, preconditioned MSCs reduced striatal neuronal loss and huntingtin aggregates in HD mice. Gene expression profiling of preconditioned MSCs revealed a robust increase in expression of genes involved in trophic effects, antioxidant, anti-apoptosis, cytokine/chemokine receptor, migration, mitochondrial energy metabolism, and stress response signaling pathways. Consistent with this finding, preconditioned MSCs demonstrated increased survival after transplantation into the brain compared to non-preconditioned cells. Our results suggest that preconditioning stem cells with the mood stabilizers lithium and VPA before transplantation may serve as an effective strategy for enhancing the therapeutic efficacy of stem cell-based therapies. Copyright © 2016. Published by Elsevier Inc.

Preconditioning of adipose tissue-derived mesenchymal stem cells with deferoxamine increases the production of pro-angiogenic, neuroprotective and anti-inflammatory factors: Potential application in the treatment of diabetic neuropathy.

PubMed

Oses, Carolina; Olivares, Belén; Ezquer, Marcelo; Acosta, Cristian; Bosch, Paul; Donoso, Macarena; Léniz, Patricio; Ezquer, Fernando

2017-01-01

Diabetic neuropathy (DN) is one of the most frequent and troublesome complications of diabetes mellitus. Evidence from diabetic animal models and diabetic patients suggests that reduced availability of neuroprotective and pro-angiogenic factors in the nerves in combination with a chronic pro-inflammatory microenvironment and high level of oxidative stress, contribute to the pathogenesis of DN. Mesenchymal stem cells (MSCs) are of great interest as therapeutic agents for regenerative purposes, since they can secrete a broad range of cytoprotective and anti-inflammatory factors. Therefore, the use of the MSC secretome may represent a promising approach for DN treatment. Recent data indicate that the paracrine potential of MSCs could be boosted by preconditioning these cells with an environmental or pharmacological stimulus, enhancing their therapeutic efficacy. In the present study, we observed that the preconditioning of human adipose tissue-derived MSCs (AD-MSCs) with 150μM or 400μM of the iron chelator deferoxamine (DFX) for 48 hours, increased the abundance of the hypoxia inducible factor 1 alpha (HIF-1α) in a concentration dependent manner, without affecting MSC morphology and survival. Activation of HIF-1α led to the up-regulation of the mRNA levels of pro-angiogenic factors like vascular endothelial growth factor alpha and angiopoietin 1. Furthermore this preconditioning increased the expression of potent neuroprotective factors, including nerve growth factor, glial cell-derived neurotrophic factor and neurotrophin-3, and cytokines with anti-inflammatory activity like IL4 and IL5. Additionally, we observed that these molecules, which could also be used as therapeutics, were also increased in the secretome of MSCs preconditioned with DFX compared to the secretome obtained from non-preconditioned cells. Moreover, DFX preconditioning significantly increased the total antioxidant capacity of the MSC secretome and they showed neuroprotective effects when evaluated in an in vitro model of DN. Altogether, our findings suggest that DFX preconditioning of AD-MSCs improves their therapeutic potential and should be considered as a potential strategy for the generation of new alternatives for DN treatment.

Preconditioning of adipose tissue-derived mesenchymal stem cells with deferoxamine increases the production of pro-angiogenic, neuroprotective and anti-inflammatory factors: Potential application in the treatment of diabetic neuropathy

PubMed Central

Oses, Carolina; Olivares, Belén; Ezquer, Marcelo; Acosta, Cristian; Bosch, Paul; Donoso, Macarena; Léniz, Patricio

2017-01-01

Diabetic neuropathy (DN) is one of the most frequent and troublesome complications of diabetes mellitus. Evidence from diabetic animal models and diabetic patients suggests that reduced availability of neuroprotective and pro-angiogenic factors in the nerves in combination with a chronic pro-inflammatory microenvironment and high level of oxidative stress, contribute to the pathogenesis of DN. Mesenchymal stem cells (MSCs) are of great interest as therapeutic agents for regenerative purposes, since they can secrete a broad range of cytoprotective and anti-inflammatory factors. Therefore, the use of the MSC secretome may represent a promising approach for DN treatment. Recent data indicate that the paracrine potential of MSCs could be boosted by preconditioning these cells with an environmental or pharmacological stimulus, enhancing their therapeutic efficacy. In the present study, we observed that the preconditioning of human adipose tissue-derived MSCs (AD-MSCs) with 150μM or 400μM of the iron chelator deferoxamine (DFX) for 48 hours, increased the abundance of the hypoxia inducible factor 1 alpha (HIF-1α) in a concentration dependent manner, without affecting MSC morphology and survival. Activation of HIF-1α led to the up-regulation of the mRNA levels of pro-angiogenic factors like vascular endothelial growth factor alpha and angiopoietin 1. Furthermore this preconditioning increased the expression of potent neuroprotective factors, including nerve growth factor, glial cell-derived neurotrophic factor and neurotrophin-3, and cytokines with anti-inflammatory activity like IL4 and IL5. Additionally, we observed that these molecules, which could also be used as therapeutics, were also increased in the secretome of MSCs preconditioned with DFX compared to the secretome obtained from non-preconditioned cells. Moreover, DFX preconditioning significantly increased the total antioxidant capacity of the MSC secretome and they showed neuroprotective effects when evaluated in an in vitro model of DN. Altogether, our findings suggest that DFX preconditioning of AD-MSCs improves their therapeutic potential and should be considered as a potential strategy for the generation of new alternatives for DN treatment. PMID:28542352

Voluntary Exercise Preconditioning Activates Multiple Antiapoptotic Mechanisms and Improves Neurological Recovery after Experimental Traumatic Brain Injury

PubMed Central

Zhao, Zaorui; Sabirzhanov, Boris; Wu, Junfang; Faden, Alan I.

2015-01-01

Abstract Physical activity can attenuate neuronal loss, reduce neuroinflammation, and facilitate recovery after brain injury. However, little is known about the mechanisms of exercise-induced neuroprotection after traumatic brain injury (TBI) or its modulation of post-traumatic neuronal cell death. Voluntary exercise, using a running wheel, was conducted for 4 weeks immediately preceding (preconditioning) moderate-level controlled cortical impact (CCI), a well-established experimental TBI model in mice. Compared to nonexercised controls, exercise preconditioning (pre-exercise) improved recovery of sensorimotor performance in the beam walk task, as well as cognitive/affective functions in the Morris water maze, novel object recognition, and tail-suspension tests. Further, pre-exercise reduced lesion size, attenuated neuronal loss in the hippocampus, cortex, and thalamus, and decreased microglial activation in the cortex. In addition, exercise preconditioning activated the brain-derived neurotrophic factor pathway before trauma and amplified the injury-dependent increase in heat shock protein 70 expression, thus attenuating key apoptotic pathways. The latter include reduction in CCI-induced up-regulation of proapoptotic B-cell lymphoma 2 (Bcl-2)-homology 3–only Bcl-2 family molecules (Bid, Puma), decreased mitochondria permeabilization with attenuated release of cytochrome c and apoptosis-inducing factor (AIF), reduced AIF translocation to the nucleus, and attenuated caspase activation. Given these neuroprotective actions, voluntary physical exercise may serve to limit the consequences of TBI. PMID:25419789

An HCG-rich microenvironment contributes to ovarian cancer cell differentiation into endothelioid cells in a three-dimensional culture system.

PubMed

Su, Min; Fan, Chao; Gao, Sainan; Shen, Aiguo; Wang, Xiaoying; Zhang, Yuquan

2015-11-01

We investigated the expression of human chorionic gonadotropin (HCG) and its effects on vasculogenic mimicry (VM) formation in ovarian cancer cells under normoxic and hypoxic conditions in three-dimensional matrices preconditioned by an endothelial-trophoblast cell co-culture system. The co-culture model was established using human umbilical vein endothelial cells (HUVECs) and HTR-8 trophoblast cells in a three-dimensional culture system. The co-cultured cells were removed with NH4OH, and ovarian cancer cells were implanted into the preconditioned matrix. VM was identified morphologically and by detecting vascular markers expressed by cancer cells. The specificity of the effects of exogenous HCG in the microenvironment was assessed by inhibition with a neutralizing anti-HCG antibody. HCG siRNA was used to knock down endogenous HCG expression in OVCAR-3 ovarian cancer cells. HTR-8 cells 'fingerprinted' HUVECs to form capillary-like tube structures in co-cultures. In the preconditioned HCG-rich microenvironment, the number of vessel-like network structures formed by HCG receptor-positive OVCAR-3 cells and the expression levels of CD31, VEGF and factor VIII were significantly increased. The preconditioned HCG-rich microenvironment significantly increased the expression of hypoxia inducible factor-1α (HIF‑1α) and VM formation in OVCAR-3 cells under hypoxic conditions. Treatment with a neutralizing anti-HCG antibody but not HCG siRNA significantly inhibited the formation of vessel-like network structures. HCG in the microenvironment contributes to OVCAR-3 differentiation into endothelioid cells in three-dimensional matrices preconditioned with an endothelial-trophoblast cell co-culture system. HCG may synergistically enhance hypoxia-induced vascular markers and HIF-1α expression. These findings would provide perspectives on new therapeutic targets for ovarian cancer.

Oxygen-glucose deprivation preconditioning protects neurons against oxygen-glucose deprivation/reperfusion induced injury via bone morphogenetic protein-7 mediated ERK, p38 and Smad signalling pathways.

PubMed

Guan, Junhong; Du, Shaonan; Lv, Tao; Qu, Shengtao; Fu, Qiang; Yuan, Ye

2016-01-01

Bone morphogenetic protein (BMP)-7 mediated neuroprotective effect of cerebral ischemic preconditioning (IPC) has been studied in an ischemic animal model, but the underlying cellular mechanisms have not been clearly clarified. In this study, primary cortical neurons and the SH-SY5Y cell line were used to investigate the role of BMP-7 and its downstream signals in the neuroprotective effects of oxygen-glucose deprivation preconditioning (OGDPC). Immunocytochemistry was used to detect the expression of neurofilament in neurons. MTT and lactate dehydrogenase activity assays were used to measure the cytotoxicity. Western blot was used to detect the protein expression of BMP-7 and downstream signals. BMP inhibitor, mitogen-activated protein kinase inhibitors, Smad inhibitor and siRNA of Smad 1 were used to investigate the role of corresponding signalling pathways in the OGDPC. Results showed that OGDPC-induced overexpression of BMP-7 in primary cortical neurons and SH-SY5Y cells. Both of endogenous and exogenous BMP-7 could replicate the neuroprotective effects seen in OGDPC pretreatment. In addition, extracellular regulated protein kinases, p38 and Smad signalling pathway were found to be involved in the neuroprotective effects mediated by OGDPC via BMP-7. This study primarily reveals the cellular mechanisms of the neuroprotection mediated by OGDPC, and provides evidence for better understanding of this intrinsic factor against ischemia. © 2015 Wiley Publishing Asia Pty Ltd.

Sulforaphane Preconditioning Sensitizes Human Colon Cancer Cells towards the Bioreductive Anticancer Prodrug PR-104A.

PubMed

Erzinger, Melanie M; Bovet, Cédric; Hecht, Katrin M; Senger, Sabine; Winiker, Pascale; Sobotzki, Nadine; Cristea, Simona; Beerenwinkel, Niko; Shay, Jerry W; Marra, Giancarlo; Wollscheid, Bernd; Sturla, Shana J

2016-01-01

The chemoprotective properties of sulforaphane (SF), derived from cruciferous vegetables, are widely acknowledged to arise from its potent induction of xenobiotic-metabolizing and antioxidant enzymes. However, much less is known about the impact of SF on the efficacy of cancer therapy through the modulation of drug-metabolizing enzymes. To identify proteins modulated by a low concentration of SF, we treated HT29 colon cancer cells with 2.5 μM SF. Protein abundance changes were detected by stable isotope labeling of amino acids in cell culture. Among 18 proteins found to be significantly up-regulated, aldo-keto reductase 1C3 (AKR1C3), bioactivating the DNA cross-linking prodrug PR-104A, was further characterized. Preconditioning HT29 cells with SF reduced the EC50 of PR-104A 3.6-fold. The increase in PR-104A cytotoxicity was linked to AKR1C3 abundance and activity, both induced by SF in a dose-dependent manner. This effect was reproducible in a second colon cancer cell line, SW620, but not in other colon cancer cell lines where AKR1C3 abundance and activity were absent or barely detectable and could not be induced by SF. Interestingly, SF had no significant influence on PR-104A cytotoxicity in non-cancerous, immortalized human colonic epithelial cell lines expressing either low or high levels of AKR1C3. In conclusion, the enhanced response of PR-104A after preconditioning with SF was apparent only in cancer cells provided that AKR1C3 is expressed, while its expression in non-cancerous cells did not elicit such a response. Therefore, a subset of cancers may be susceptible to combined food-derived component and prodrug treatments with no harm to normal tissues.

Remote ischemic preconditioning protects liver ischemia-reperfusion injury by regulating eNOS-NO pathway and liver microRNA expressions in fatty liver rats.

PubMed

Duan, Yun-Fei; An, Yong; Zhu, Feng; Jiang, Yong

2017-08-15

Ischemic preconditioning (IPC) is a strategy to reduce ischemia-reperfusion (I/R) injury. The protective effect of remote ischemic preconditioning (RIPC) on liver I/R injury is not clear. This study aimed to investigate the roles of RIPC in liver I/R in fatty liver rats and the involvement of endothelial nitric oxide synthase-nitric oxide (eNOS-NO) pathway and microRNA expressions in this process. A total of 32 fatty rats were randomly divided into the sham group, I/R group, RIPC group and RIPC+I/R group. Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and nitric oxide (NO) were measured. Hematoxylin-eosin staining was used to observe histological changes of liver tissues, TUNEL to detect hepatocyte apoptosis, and immunohistochemistry assay to detect heat shock protein 70 (HSP70) expression. Western blotting was used to detect liver inducible NOS (iNOS) and eNOS protein levels and real-time quantitative polymerase chain reaction to detect miR-34a, miR-122 and miR-27b expressions. Compared with the sham and RIPC groups, serum ALT, AST and iNOS in liver tissue were significantly higher in other two groups, while serum NO and eNOS in liver tissue were lower, and varying degrees of edema, degeneration and inflammatory cell infiltration were found. Cell apoptosis number was slightly lower in the RIPC+I/R group than that in I/R group. Compared with the sham group, HSP70 expressions were significantly increased in other three groups (all P<0.05). Compared with the sham and RIPC groups, elevated miR-34a expressions were found in I/R and RIPC+I/R groups (P<0.05). MiR-122 and miR-27b were found significantly decreased in I/R and RIPC+I/R groups compared with the sham and RIPC groups (all P<0.05). RIPC can reduce fatty liver I/R injury by affecting the eNOS-NO pathway and liver microRNA expressions. Copyright © 2017 The Editorial Board of Hepatobiliary & Pancreatic Diseases International. Published by Elsevier B.V. All rights reserved.

Redox signaling in remote ischemic preconditioning-induced cardioprotection: Evidences and mechanisms.

PubMed

Singh, Lovedeep; Randhawa, Puneet Kaur; Singh, Nirmal; Jaggi, Amteshwar Singh

2017-08-15

Reactive oxygen species are the reactive molecules that are derived from molecular oxygen and play an important role as redox signaling molecules to confer cardioprotection. Various scientists have demonstrated the key role of redox signaling in cardioprotection by showing a transient increase in their levels during remote ischemic preconditioning (RIPC) phase. The transient increase in reactive oxygen species levels during remote preconditioning phase may take place either through activation of K ATP channels or through increased nitric oxide (NO) production. A transient increase in reactive oxygen species during preconditioning may also increase the expression of heat shock proteins (HSP), the level of antioxidant enzymes and decrease the expression of inflammatory genes (Egr-1) during ischemia-reperfusion phase to confer cardioprotection. The present review describes the role of redox signaling in RIPC-induced cardioprotective effect with possible mechanisms. Copyright © 2017 Elsevier B.V. All rights reserved.

Platelet rich plasma clot releasate preconditioning induced PI3K/AKT/NFκB signaling enhances survival and regenerative function of rat bone marrow mesenchymal stem cells in hostile microenvironments.

PubMed

Peng, Yan; Huang, Sha; Wu, Yan; Cheng, Biao; Nie, Xiaohu; Liu, Hongwei; Ma, Kui; Zhou, Jiping; Gao, Dongyun; Feng, Changjiang; Yang, Siming; Fu, Xiaobing

2013-12-15

Mesenchymal stem cells (MSCs) have been optimal targets in the development of cell based therapies, but their limited availability and high death rate after transplantation remains a concern in clinical applications. This study describes novel effects of platelet rich clot releasate (PRCR) on rat bone marrow-derived MSCs (BM-MSCs), with the former driving a gene program, which can reduce apoptosis and promote the regenerative function of the latter in hostile microenvironments through enhancement of paracrine/autocrine factors. By using reverse transcription-polymerase chain reaction, immunofluorescence and western blot analyses, we showed that PRCR preconditioning could alleviate the apoptosis of BM-MSCs under stress conditions induced by hydrogen peroxide (H2O2) and serum deprivation by enhancing expression of vascular endothelial growth factor and platelet-derived growth factor (PDGF) via stimulation of the platelet-derived growth factor receptor (PDGFR)/PI3K/AKT/NF-κB signaling pathways. Furthermore, the effects of PRCR preconditioned GFP-BM-MSCs subcutaneously transplanted into rats 6 h after wound surgery were examined by histological and other tests from days 0-22 after transplantation. Engraftment of the PRCR preconditioned BM-MSCs not only significantly attenuated apoptosis and wound size but also improved epithelization and blood vessel regeneration of skin via regulation of the wound microenvironment. Thus, preconditioning with PRCR, which reprograms BM-MSCs to tolerate hostile microenvironments and enhance regenerative function by increasing levels of paracrine factors through PDGFR-α/PI3K/AKT/NF-κB signaling pathways would be a safe method for boosting the effectiveness of transplantation therapy in the clinic.

Exosomes derived from hypoxia-preconditioned mesenchymal stromal cells ameliorate cognitive decline by rescuing synaptic dysfunction and regulating inflammatory responses in APP/PS1 mice.

PubMed

Cui, Guo-Hong; Wu, Jing; Mou, Fang-Fang; Xie, Wei-Hua; Wang, Fu-Bo; Wang, Qiang-Li; Fang, Jie; Xu, Yan-Wu; Dong, You-Rong; Liu, Jian-Ren; Guo, Hai-Dong

2018-02-01

Administration of exosomes derived from mesenchymal stromal cells (MSCs) could improve some neurologic conditions by transferring functional biomolecules to recipient cells. Furthermore, exosomes from hypoxic progenitor cells exerted better therapeutic effects in organ injury through specific cargoes. However, there are no related reports about whether exosomes derived from MSCs or hypoxia-preconditioned MSCs (PC-MSCs) could prevent memory deficits in Alzheimer disease (AD). In this study, the exosomes derived from MSCs or PC-MSCs were systemically administered to transgenic APP/PS1 mice. The expression of miR-21 in MSCs was significantly increased after hypoxic treatment. Injection of exosomes from normoxic MSCs could rescue cognition and memory impairment according to results of the Morris water maze test, reduced plaque deposition, and Aβ levels in the brain; could decrease the activation of astrocytes and microglia; could down-regulate proinflammatory cytokines (TNF-α and IL-1β); and could up-regulate anti-inflammatory cytokines (IL-4 and -10) in AD mice, as well as reduce the activation of signal transducer and activator of transcription 3 (STAT3) and NF-κB. Compared to the group administered exosomes from normoxic MSCs, in the group administered exosomes from PC-MSCs, learning and memory capabilities were significantly improved; the plaque deposition and Aβ levels were lower, and expression of growth-associated protein 43, synapsin 1, and IL-10 was increased; and the levels of glial fibrillary acidic protein, ionized calcium-binding adaptor molecule 1, TNF-α, IL-1β, and activation of STAT3 and NF-κB were sharply decreased. More importantly, exosomes from PC-MSCs effectively increased the level of miR-21 in the brain of AD mice. Additionally, replenishment of miR-21 restored the cognitive deficits in APP/PS1 mice and prevented pathologic features. Taken together, these findings suggest that exosomes from PC-MSCs could improve the learning and memory capabilities of APP/PS1 mice, and that the underlying mechanism may lie in the restoration of synaptic dysfunction and regulation of inflammatory responses through regulation of miR-21.-Cui, G.-H., Wu, J., Mou, F.-F., Xie, W.-H., Wang, F.-B., Wang, Q.-L., Fang, J., Xu, Y.-W., Dong, Y.-R., Liu, J.-R., Guo, H.-D. Exosomes derived from hypoxia-preconditioned mesenchymal stromal cells ameliorate cognitive decline by rescuing synaptic dysfunction and regulating inflammatory responses in APP/PS1 mice.

Morphine preconditioning confers cardioprotection in doxorubicin-induced failing rat hearts via ERK/GSK-3β pathway independent of PI3K/Akt

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

He, Shu-Fang; Jin, Shi-Yun; Wu, Hao

Preconditioning against myocardial ischemia–reperfusion (I/R) injury can be suppressed in some pathological conditions. This study was designed to investigate whether morphine preconditioning (MPC) exerts cardioprotection in doxorubicin (DOX)-induced heart failure in rats and the mechanisms involved. Phosphatidylinositol-3 kinase/protein kinase B (PI3K/Akt), extracellular signal-regulated kinase (ERK) and glycogen synthase kinase (GSK)-3β pathways were examined. Normal and DOX-induced failing rat hearts were subjected to I/R injury using a Langendorff perfusion system with or without MPC or ischemic preconditioning (IPC). The PI3K inhibitor (wortmannin) or ERK inhibitor (PD98059) was infused before MPC. In normal hearts, both MPC and IPC significantly reduced infarct sizemore » and the rise in lactate dehydrogenase (LDH) level caused by I/R injury. Pretreatment with wortmannin or PD98059 abrogated the protective effects of MPC and suppressed the phosphorylation of Akt, ERK and GSK-3β. In failing rat hearts, however, MPC retained its cardioprotection while IPC did not. This protective effect was abolished by PD98059 but not wortmannin. MPC increased the level of p-ERK rather than p-Akt. The phosphorylation of GSK-3β induced by MPC was reversed by PD98059 only. IPC did not elevate the expression of p-ERK, p-Akt and p-GSK-3β in failing rat hearts. We conclude that MPC is cardioprotective in rats with DOX-induced heart failure while IPC is not. The effect of MPC appears to be mediated via the ERK/GSK-3β pathway independent of PI3K/Akt. - Highlights: • Morphine and ischemic preconditioning are cardioprotective in normal rat hearts. • Ischemic preconditioning fails to confer cardioprotection in rats with heart failure. • Morphine retains cardioprotection in doxorubicin-induced heart failure. • Morphine exerts cardioprotection via the ERK/GSK-β pathway independent of PI3K/Akt.« less

Hypoxia preconditioning increases survival and decreases expression of Toll-like receptor 4 in pulmonary artery endothelial cells exposed to lipopolysaccharide.

PubMed

Ali, Irshad; Nanchal, Rahul; Husnain, Fouad; Audi, Said; Konduri, G Ganesh; Densmore, John C; Medhora, Meetha; Jacobs, Elizabeth R

2013-09-01

Abstract Pulmonary or systemic infections and hypoxemic respiratory failure are among the leading causes of admission to intensive care units, and these conditions frequently exist in sequence or in tandem. Inflammatory responses to infections are reproduced by lipopolysaccharide (LPS) engaging Toll-like receptor 4 (TLR4). Apoptosis is a hallmark of lung injury in sepsis. This study was conducted to determine whether preexposure to LPS or hypoxia modulated the survival of pulmonary artery endothelial cells (PAECs). We also investigated the role TLR4 receptor expression plays in apoptosis due to these conditions. Bovine PAECs were cultured in hypoxic or normoxic environments and treated with LPS. TLR4 antagonist TAK-242 was used to probe the role played by TLR4 receptors in cell survival. Cell apoptosis and survival were measured by caspase 3 activity and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) incorporation. TLR4 expression and tumor necrosis factor α (TNF-α) production were also determined. LPS increased caspase 3 activity in a TAK-242-sensitive manner and decreased MTT incorporation. Apoptosis was decreased in PAECs preconditioned with hypoxia prior to LPS exposure. LPS increased TNF-α production, and hypoxic preconditioning blunted it. Hypoxic preconditioning reduced LPS-induced TLR4 messenger RNA and TLR4 protein. TAK-242 decreased to baseline the LPS-stimulated expression of TLR4 messenger RNA regardless of environmental conditions. In contrast, LPS followed by hypoxia substantially increased apoptosis and cell death. In conclusion, protection from LPS-stimulated PAEC apoptosis by hypoxic preconditioning is attributable in part to reduction in TLR4 expression. If these signaling pathways apply to septic patients, they may account for differing sensitivities of individuals to acute lung injury depending on oxygen tensions in PAECs in vivo.

Interleukin-3 enhances the migration of human mesenchymal stem cells by regulating expression of CXCR4.

PubMed

Barhanpurkar-Naik, Amruta; Mhaske, Suhas T; Pote, Satish T; Singh, Kanupriya; Wani, Mohan R

2017-07-14

Mesenchymal stem cells (MSCs) represent an important source for cell therapy in regenerative medicine. MSCs have shown promising results for repair of damaged tissues in various degenerative diseases in animal models and also in human clinical trials. However, little is known about the factors that could enhance the migration and tissue-specific engraftment of exogenously infused MSCs for successful regenerative cell therapy. Previously, we have reported that interleukin-3 (IL-3) prevents bone and cartilage damage in animal models of rheumatoid arthritis and osteoarthritis. Also, IL-3 promotes the differentiation of human MSCs into functional osteoblasts and increases their in-vivo bone regenerative potential in immunocompromised mice. However, the role of IL-3 in migration of MSCs is not yet known. In the present study, we investigated the role of IL-3 in migration of human MSCs under both in-vitro and in-vivo conditions. MSCs isolated from human bone marrow, adipose and gingival tissues were used for in-vitro cell migration, motility and wound healing assays in the presence or absence of IL-3. The effect of IL-3 preconditioning on expression of chemokine receptors and integrins was examined by flow cytometry and real-time PCR. The in-vivo migration of IL-3-preconditioned MSCs was investigated using a subcutaneous matrigel-releasing stromal cell-derived factor-1 alpha (SDF-1α) model in immunocompromised mice. We observed that human MSCs isolated from all three sources express IL-3 receptor-α (IL-3Rα) both at gene and protein levels. IL-3 significantly enhances in-vitro migration, motility and wound healing abilities of MSCs. Moreover, IL-3 preconditioning upregulates expression of chemokine (C-X-C motif) receptor 4 (CXCR4) on MSCs, which leads to increased migration of cells towards SDF-1α. Furthermore, CXCR4 antagonist AMD3100 decreases the migration of IL-3-treated MSCs towards SDF-1α. Importantly, IL-3 also induces in-vivo migration of MSCs towards subcutaneously implanted matrigel-releasing-SDF-1α in immunocompromised mice. The present study demonstrates for the first time that IL-3 has an important role in enhancing the migration of human MSCs through regulation of the CXCR4/SDF-1α axis. These findings suggest a potential role of IL-3 in improving the efficacy of MSCs in regenerative cell therapy.

Effect of limb ischemic preconditioning on myocardial apoptosis-related proteins in ischemia-reperfusion injury

PubMed Central

GAO, JIANZHI; ZHAO, LINJING; WANG, YONGLING; TENG, QINGLEI; LIANG, LIDONG; ZHANG, JINYING

2013-01-01

The aim of this study was to investigate the effect of limb ischemic preconditioning (LIPC) on myocardial apoptosis in myocardial ischemia-reperfusion injury (MIRI), as well as the regulation of caspase-3 and the B cell lymphoma 2 (Bcl-2) gene in LIPC. A total of 50 rats were divided randomly into 5 groups (n=10). Four rats in each group were drawn out for detection of apoptosis. The sham, MIRI and LIPC groups underwent surgery without additional treatment. In the LY294002 group, LY294002 preconditioning was administered 15 min before reperfusion. In the LY294002+LIPC group, following LIPC, LY294002 was administered 15 min before reperfusion. The relative expression of myocardial Bcl-2 and caspase-3 mRNA and the apoptotic index for each group were determined by reverse transcription-polymerase chain reaction (RT-PCR) and terminal deoxynucleotidyl transferase deoxyuridine triphosphate (dUTP) nick end labeling (TUNEL), respectively. The ultrastructure of the cardiac muscle tissues was observed by election microscopy. Compared with the sham group, the expression of caspase-3 mRNA in the MIRI group significantly increased (P<0.05) and the expression of Bcl-2 mRNA clearly decreased. Compared with the MIRI group, LIPC reduced the expression of caspase-3 and increased the expression of Bcl-2 mRNA (P<0.05). There were no significant differences between the LY294002+LIPC group and the MIRI group. Compared with the sham group, the apoptotic index of myocardial cells in the MIRI group significantly increased (P<0.05). Compared with the MIRI group, LIPC significantly decreased the apoptotic index of myocardial cells (P<0.05) and LY294002 increased the apoptotic index of myocardial cells. Compared with the LIPC group, LY294002+LIPC significantly increased the apoptotic index of myocardial cells (P<0.05). There were no significant differences between the LY294002+LIPC and MIRI groups. In conclusion, LIPC increased the expression of Bcl-2 and decreased caspase-3 mRNA and apoptosis in myocardial tissue following MIRI. Therefore, LIPC plays a protective role in myocardial tissue. PMID:23737869

Ischemic preconditioning inhibits over-expression of arginyl-tRNA synthetase gene Rars in ischemia-injured neurons.

PubMed

Shen, Yin; Zhao, Hong-Yang; Wang, Hai-Jun; Wang, Wen-Liang; Zhang, Li-Zhi; Fu, Rong

2016-08-01

The expression changes of Rars gene in ischemia-injured neurons were investigated by detecting its translational product arginyl-tRNA synthetase (ArgRS), and the inhibitory effects of ischemic preconditioning (IPC) on Rars gene were explored. Both IPC model and prolonged ischemia (PI) model were established by using the classic oxygen glucose deprivation (OGD) method. The primary cultured neurons were assigned into the following groups: the experimental group (IPC+PI group), undergoing PI after a short period of IPC; the conditional control group (PI control group), subjected to PI without IPC; blank control group, the normally cultured neurons. The Rars transcriptional activities and ArgRS expression levels were measured at different time points after re-oxygenation (3 h/6 h/12 h/24 h). Data were collected and statistically analyzed. Compared to the blank control group, the Rars activities and ArgRS levels were significantly increased in PI control group, peaking at the time point of 6 h after re-oxygenation. Rars activities and ArgRS levels were significantly lower in the experimental group than in the PI control group at different time points after re-oxygenation. PI insult can induce an escalating activity of Rars and lead to ArgRS over-expression in primary cultured neurons. IPC can inhibit the increased Rars activity and down-regulate ArgRS expression of ischemia-insulted neurons. This mechanism may confer ischemic tolerance on neurons.

Fetal asphyctic preconditioning alters the transcriptional response to perinatal asphyxia.

PubMed

Cox-Limpens, Kimberly E M; Vles, Johan S H; LA van den Hove, Daniel; Zimmermann, Luc J I; Gavilanes, Antonio W D

2014-05-29

Genomic reprogramming is thought to be, at least in part, responsible for the protective effect of brain preconditioning. Unraveling mechanisms of this endogenous neuroprotection, activated by preconditioning, is an important step towards new clinical strategies for treating asphyctic neonates.Therefore, we investigated whole-genome transcriptional changes in the brain of rats which underwent perinatal asphyxia (PA), and rats where PA was preceded by fetal asphyctic preconditioning (FAPA). Offspring were sacrificed 6 h and 96 h after birth, and whole-genome transcription was investigated using the Affymetrix Gene1.0ST chip. Microarray data were analyzed with the Bioconductor Limma package. In addition to univariate analysis, we performed Gene Set Enrichment Analysis (GSEA) in order to derive results with maximum biological relevance. We observed minimal, 25% or less, overlap of differentially regulated transcripts across different experimental groups which leads us to conclude that the transcriptional phenotype of these groups is largely unique. In both the PA and FAPA group we observe an upregulation of transcripts involved in cellular stress. Contrastingly, transcripts with a function in the cell nucleus were mostly downregulated in PA animals, while we see considerable upregulation in the FAPA group. Furthermore, we observed that histone deacetylases (HDACs) are exclusively regulated in FAPA animals. This study is the first to investigate whole-genome transcription in the neonatal brain after PA alone, and after perinatal asphyxia preceded by preconditioning (FAPA). We describe several genes/pathways, such as ubiquitination and proteolysis, which were not previously linked to preconditioning-induced neuroprotection. Furthermore, we observed that the majority of upregulated genes in preconditioned animals have a function in the cell nucleus, including several epigenetic players such as HDACs, which suggests that epigenetic mechanisms are likely to play a role in preconditioning-induced neuroprotection.

Fetal asphyctic preconditioning alters the transcriptional response to perinatal asphyxia

PubMed Central

2014-01-01

Background Genomic reprogramming is thought to be, at least in part, responsible for the protective effect of brain preconditioning. Unraveling mechanisms of this endogenous neuroprotection, activated by preconditioning, is an important step towards new clinical strategies for treating asphyctic neonates. Therefore, we investigated whole-genome transcriptional changes in the brain of rats which underwent perinatal asphyxia (PA), and rats where PA was preceded by fetal asphyctic preconditioning (FAPA). Offspring were sacrificed 6 h and 96 h after birth, and whole-genome transcription was investigated using the Affymetrix Gene1.0ST chip. Microarray data were analyzed with the Bioconductor Limma package. In addition to univariate analysis, we performed Gene Set Enrichment Analysis (GSEA) in order to derive results with maximum biological relevance. Results We observed minimal, 25% or less, overlap of differentially regulated transcripts across different experimental groups which leads us to conclude that the transcriptional phenotype of these groups is largely unique. In both the PA and FAPA group we observe an upregulation of transcripts involved in cellular stress. Contrastingly, transcripts with a function in the cell nucleus were mostly downregulated in PA animals, while we see considerable upregulation in the FAPA group. Furthermore, we observed that histone deacetylases (HDACs) are exclusively regulated in FAPA animals. Conclusions This study is the first to investigate whole-genome transcription in the neonatal brain after PA alone, and after perinatal asphyxia preceded by preconditioning (FAPA). We describe several genes/pathways, such as ubiquitination and proteolysis, which were not previously linked to preconditioning-induced neuroprotection. Furthermore, we observed that the majority of upregulated genes in preconditioned animals have a function in the cell nucleus, including several epigenetic players such as HDACs, which suggests that epigenetic mechanisms are likely to play a role in preconditioning-induced neuroprotection. PMID:24885038

The role of hypoxia-inducible factor-1α and vascular endothelial growth factor in late-phase preconditioning with xenon, isoflurane and levosimendan in rat cardiomyocytes

PubMed Central

Goetzenich, Andreas; Hatam, Nima; Preuss, Stephanie; Moza, Ajay; Bleilevens, Christian; Roehl, Anna B.; Autschbach, Rüdiger; Bernhagen, Jürgen; Stoppe, Christian

2014-01-01

OBJECTIVES The protective effects of late-phase preconditioning can be triggered by several stimuli. Unfortunately, the transfer from bench to bedside still represents a challenge, as concomitant medication or diseases influence the complex signalling pathways involved. In an established model of primary neonatal rat cardiomyocytes, we analysed the cardioprotective effects of three different stimulating pharmaceuticals of clinical relevance. The effect of additional β-blocker treatment was studied as these were previously shown to negatively influence preconditioning. METHODS Twenty-four hours prior to hypoxia, cells pre-treated with or without metoprolol (0.55 µg/ml) were preconditioned with isoflurane, levosimendan or xenon. The influences of these stimuli on hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF) as well as inducible and endothelial nitric synthase (iNOS/eNOS) and cyclooxygenase-2 (COX-2) were analysed by polymerase chain reaction and western blotting. The preconditioning was proved by trypan blue cell counts following 5 h of hypoxia and confirmed by fluorescence staining. RESULTS Five hours of hypoxia reduced cell survival in unpreconditioned control cells to 44 ± 4%. Surviving cell count was significantly higher in cells preconditioned either by 2 × 15 min isoflurane (70 ± 16%; P = 0.005) or by xenon (59 ± 8%; P = 0.049). Xenon-preconditioned cells showed a significantly elevated content of VEGF (0.025 ± 0.010 IDV [integrated density values when compared with GAPDH] vs 0.003 ± 0.006 IDV in controls; P = 0.0003). The protein expression of HIF-1α was increased both by levosimendan (0.563 ± 0.175 IDV vs 0.142 ± 0.042 IDV in controls; P = 0.0289) and by xenon (0.868 ± 0.222 IDV; P < 0.0001) pretreatment. A significant elevation of mRNA expression of iNOS was measureable following preconditioning by xenon but not by the other chosen stimuli. eNOS mRNA expression was found to be suppressed by β-blocker treatment for all stimuli. In our model, independently of the chosen stimulus, β-blocker treatment had no significant effect on cell survival. CONCLUSIONS We found that the stimulation of late-phase preconditioning involves several distinct pathways that are variably addressed by the different stimuli. In contrast to isoflurane treatment, xenon-induced preconditioning does not lead to an increase in COX-2 gene transcription but to a significant increase in HIF-1α and subsequently VEGF. PMID:24351506

The role of hypoxia-inducible factor-1α and vascular endothelial growth factor in late-phase preconditioning with xenon, isoflurane and levosimendan in rat cardiomyocytes.

PubMed

Goetzenich, Andreas; Hatam, Nima; Preuss, Stephanie; Moza, Ajay; Bleilevens, Christian; Roehl, Anna B; Autschbach, Rüdiger; Bernhagen, Jürgen; Stoppe, Christian

2014-03-01

The protective effects of late-phase preconditioning can be triggered by several stimuli. Unfortunately, the transfer from bench to bedside still represents a challenge, as concomitant medication or diseases influence the complex signalling pathways involved. In an established model of primary neonatal rat cardiomyocytes, we analysed the cardioprotective effects of three different stimulating pharmaceuticals of clinical relevance. The effect of additional β-blocker treatment was studied as these were previously shown to negatively influence preconditioning. Twenty-four hours prior to hypoxia, cells pre-treated with or without metoprolol (0.55 µg/ml) were preconditioned with isoflurane, levosimendan or xenon. The influences of these stimuli on hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF) as well as inducible and endothelial nitric synthase (iNOS/eNOS) and cyclooxygenase-2 (COX-2) were analysed by polymerase chain reaction and western blotting. The preconditioning was proved by trypan blue cell counts following 5 h of hypoxia and confirmed by fluorescence staining. Five hours of hypoxia reduced cell survival in unpreconditioned control cells to 44 ± 4%. Surviving cell count was significantly higher in cells preconditioned either by 2 × 15 min isoflurane (70 ± 16%; P = 0.005) or by xenon (59 ± 8%; P = 0.049). Xenon-preconditioned cells showed a significantly elevated content of VEGF (0.025 ± 0.010 IDV [integrated density values when compared with GAPDH] vs 0.003 ± 0.006 IDV in controls; P = 0.0003). The protein expression of HIF-1α was increased both by levosimendan (0.563 ± 0.175 IDV vs 0.142 ± 0.042 IDV in controls; P = 0.0289) and by xenon (0.868 ± 0.222 IDV; P < 0.0001) pretreatment. A significant elevation of mRNA expression of iNOS was measureable following preconditioning by xenon but not by the other chosen stimuli. eNOS mRNA expression was found to be suppressed by β-blocker treatment for all stimuli. In our model, independently of the chosen stimulus, β-blocker treatment had no significant effect on cell survival. We found that the stimulation of late-phase preconditioning involves several distinct pathways that are variably addressed by the different stimuli. In contrast to isoflurane treatment, xenon-induced preconditioning does not lead to an increase in COX-2 gene transcription but to a significant increase in HIF-1α and subsequently VEGF.

[Effects of circulating microvesicles derived from myocardial ischemic preconditioning on myocardial ischemia/reperfusion injury in rats].

PubMed

Wang, Yi-Lu; Liu, Miao; Shang, Man; Wang, Yao; Zhang, Qi; Wang, Shao-Xun; Wei, Su; Zhang, Kun-Wei; Liu, Chao; Wu, Yan-Na; Song, Jun-Qiu; Liu, Yan-Xia

2016-02-08

To investigate the effects of circulating microvesicles (MVs) derived from ischemic preconditioning (IPC) on myocardial ischemia/reperfusion (I/R) injury in rats and explore the underlying mechanism. To establish the IPC model, the rats were subjected to brief cycles of left anterior descending (LAD) coronary occlusion and reperfusion. The blood was drawn from abdominal aorta once the operation was finished. IPC-MVs were isolated by ultracentrifugation from the peripheral blood and characterized by flow cytometry. The myocardial I/R model of rats was established in vivo. Rats were injected via the femoral vein with IPC-MVs at 7 mg/kg. Morphological changes of myocardium were observed microscopically after HE staining. Apoptosis of myocardial cells was detected with TUNEL assay. Myocardial infarct size was detected by TTC staining. Moreover, activity of plasma lactate dehydrogenase (LDH) was tested by colorimetry. The activity of caspase 3 in myocardium was assayed with spectrophotometry. Expression levels of Bcl-2 and Bax protein were examined with Western blot. The concentration of IPC-MVs, which was detected by flow cytometry, was 4380±745 cells/ μ l. Compared with I/R group, IPC-MVs alleviated the damage of tissues in I/R injured rats significantly. The myocardial infarct size and the cardiomyocyte apoptotic index were obviously decreased after IPC-MVs treatment ( P <0.01, respectively). The activity of plasma LDH was significantly decreased in IPC-MVs treated rats ( P <0.01). Moreover, the activity of caspase 3 was markedly decreased after IPC-MVs treatment ( P <0.01). In addition, the expression of Bcl-2 was increased ( P <0.01), the expression of Bax was decreased ( P <0.01), the ratio of Bcl-2/Bax was significantly increased after IPC-MVs treatment ( P <0.01). IPC-MVs protected myocardial against I/R injury by up-regulating the expression of Bcl-2 protein, down-regulating the expression of Bax protein, increasing the ratio of Bcl-2/Bax and decreasing cleavage of caspase 3.

Increased leptin by hypoxic-preconditioning promotes autophagy of mesenchymal stem cells and protects them from apoptosis.

PubMed

Wang, LiHan; Hu, XinYang; Zhu, Wei; Jiang, Zhi; Zhou, Yu; Chen, PanPan; Wang, JianAn

2014-02-01

Autophagy is the basic catabolic progress involved in cell degradation of unnecessary or dysfunctional cellular components. It has been proven that autophagy could be utilized for cell survival under stresses. Hypoxic-preconditioning (HPC) could reduce apoptosis induced by ischemia and hypoxia/serum deprivation (H/SD) in bone marrow-derived mesenchymal stem cells (BMSCs). Previous studies have shown that both leptin signaling and autophagy activation were involved in the protection against apoptosis induced by various stress, including ischemia-reperfusion. However, it has never been fully understood how leptin was involved in the protective effects conferred by autophagy. In the present study, we demonstrated that HPC can induce autophagy in BMSCs by increased LC3-II/LC3-I ratio and autophagosome formation. Interestingly, similar effects were also observed when BMSCs were pretreated with rapamycin. The beneficial effects offered by HPC were absent when BMSCs were incubated with autophagy inhibitor, 3-methyladenine (3-MA). In addition, down-regulated leptin expression by leptin-shRNA also attenuated HPC-induced autophagy in BMSCs, which in turn was associated with increased apoptosis after exposed to sustained H/SD. Furthermore, increased AMP-activated protein kinase phosphorylation and decreased mammalian target of rapamycin phosphorylation that were observed in HPC-treated BMSCs can also be attenuated by down-regulation of leptin expression. Our data suggests that leptin has impact on HPC-induced autophagy in BMSCs which confers protection against apoptosis under H/SD, possibly through modulating both AMPK and mTOR pathway.

Ischemic preconditioning increases GSK-3β/β-catenin levels and ameliorates liver ischemia/reperfusion injury in rats.

PubMed

Yan, Yichao; Li, Guangying; Tian, Xiaofeng; Ye, Yingjiang; Gao, Zhidong; Yao, Jihong; Zhang, Feng; Wang, Shan

2015-06-01

Ischemic preconditioning (IPC) ameliorates ischemia/reperfusion (I/R) injury in a number of organs, and the glycogen synthase kinase-3β (GSK-3β)/β-catenin signaling pathway regulates I/R-induced proliferation and apoptosis in the central nervous system and heart. However, the function of this signaling pathway in IPC during liver I/R remains unclear. Thus, in this study, we aimed to investigte the role of the GSK-3β/β-catenin pathway during I/R and following ischemic preconditioning. For this purpose, 30 Sprague-Dawley rats were randomly divided into the sham-operated, the I/R and the IPC groups (n=10). Following reperfusion, liver pathology, as well as alanine aminotransferase (ALT), aspartate aminotransferase (AST), maleic dialdehyde (MDA) and superoxide dismutase (SOD) levels were assessed. Western blot analysis was performed to quantify the GSK-3β, Ser9-phospho-GSK-3β (p-GSK-3β), cytosolic and nuclear β-catenin, vascular endothelial growth factor (VEGF), Bcl-2 and survivin levels. In addition, the Bcl-2 and survivin mRNA levels were assessed by RT-qPCR. Compared with the sham-operated group, I/R increased serum ALT, AST and MDA activity and decreased SOD levels, while IPC significantly decreased serum ALT, AST and MDA activity and increased SOD levels, compared with the I/R group. Simultaneously, I/R increased p-GSK-3β protein expression, and decreased Bcl-2 and survivin protein and mRNA levels. IPC further increased the protein expression of p-GSK-3β, and also increased cytosolic and nuclear β-catenin and VEGF expression compared with the I/R group; the expression of Bcl-2 and survivin was also increased by IPC, both at the mRNA and protein level. The total GSK-3β expression remained unaltered in all the groups. In conclusion, our data demonstrate that IPC exerts protective effects against liver injury induced by I/R and activates the GSK-3β/β-catenin signaling pathway.

Preconditioning with Endoplasmic Reticulum Stress Ameliorates Endothelial Cell Inflammation

PubMed Central

Leonard, Antony; Paton, Adrienne W.; El-Quadi, Monaliza; Paton, James C.; Fazal, Fabeha

2014-01-01

Endoplasmic Reticulum (ER) stress, caused by disturbance in ER homeostasis, has been implicated in several pathological conditions such as ischemic injury, neurodegenerative disorders, metabolic diseases and more recently in inflammatory conditions. Our present study aims at understanding the role of ER stress in endothelial cell (EC) inflammation, a critical event in the pathogenesis of acute lung injury (ALI). We found that preconditioning human pulmonary artery endothelial cells (HPAEC) to ER stress either by depleting ER chaperone and signaling regulator BiP using siRNA, or specifically cleaving (inactivating) BiP using subtilase cytotoxin (SubAB), alleviates EC inflammation. The two approaches adopted to abrogate BiP function induced ATF4 protein expression and the phosphorylation of eIF2α, both markers of ER stress, which in turn resulted in blunting the activation of NF-κB, and restoring endothelial barrier integrity. Pretreatment of HPAEC with BiP siRNA inhibited thrombin-induced IκBα degradation and its resulting downstream signaling pathway involving NF-κB nuclear translocation, DNA binding, phosphorylation at serine536, transcriptional activation and subsequent expression of adhesion molecules. However, TNFα-mediated NF-κB signaling was unaffected upon BiP knockdown. In an alternative approach, SubAB-mediated inactivation of NF-κB was independent of IκBα degradation. Mechanistic analysis revealed that pretreatment of EC with SubAB interfered with the binding of the liberated NF-κB to the DNA, thereby resulting in reduced expression of adhesion molecules, cytokines and chemokines. In addition, both knockdown and inactivation of BiP stimulated actin cytoskeletal reorganization resulting in restoration of endothelial permeability. Together our studies indicate that BiP plays a central role in EC inflammation and injury via its action on NF-κB activation and regulation of vascular permeability. PMID:25356743

Preconditioning with endoplasmic reticulum stress ameliorates endothelial cell inflammation.

PubMed

Leonard, Antony; Paton, Adrienne W; El-Quadi, Monaliza; Paton, James C; Fazal, Fabeha

2014-01-01

Endoplasmic Reticulum (ER) stress, caused by disturbance in ER homeostasis, has been implicated in several pathological conditions such as ischemic injury, neurodegenerative disorders, metabolic diseases and more recently in inflammatory conditions. Our present study aims at understanding the role of ER stress in endothelial cell (EC) inflammation, a critical event in the pathogenesis of acute lung injury (ALI). We found that preconditioning human pulmonary artery endothelial cells (HPAEC) to ER stress either by depleting ER chaperone and signaling regulator BiP using siRNA, or specifically cleaving (inactivating) BiP using subtilase cytotoxin (SubAB), alleviates EC inflammation. The two approaches adopted to abrogate BiP function induced ATF4 protein expression and the phosphorylation of eIF2α, both markers of ER stress, which in turn resulted in blunting the activation of NF-κB, and restoring endothelial barrier integrity. Pretreatment of HPAEC with BiP siRNA inhibited thrombin-induced IκBα degradation and its resulting downstream signaling pathway involving NF-κB nuclear translocation, DNA binding, phosphorylation at serine536, transcriptional activation and subsequent expression of adhesion molecules. However, TNFα-mediated NF-κB signaling was unaffected upon BiP knockdown. In an alternative approach, SubAB-mediated inactivation of NF-κB was independent of IκBα degradation. Mechanistic analysis revealed that pretreatment of EC with SubAB interfered with the binding of the liberated NF-κB to the DNA, thereby resulting in reduced expression of adhesion molecules, cytokines and chemokines. In addition, both knockdown and inactivation of BiP stimulated actin cytoskeletal reorganization resulting in restoration of endothelial permeability. Together our studies indicate that BiP plays a central role in EC inflammation and injury via its action on NF-κB activation and regulation of vascular permeability.

Innate Immune Regulation by Toll-Like Receptors in the Brain

PubMed Central

Mallard, Carina

2012-01-01

The innate immune system plays an important role in cerebral health and disease. In recent years the role of innate immune regulation by toll-like receptors in the brain has been highlighted. In this paper the expression of toll-like receptors and endogenous toll-like receptor ligands in the brain and their role in cerebral ischemia will be discussed. Further, the ability of systemic toll-like receptor ligands to induce cerebral inflammation will be reviewed. Finally, the capacity of toll-like receptors to both increase (sensitization) and decrease (preconditioning/tolerance) the vulnerability of the brain to damage will be disclosed. Studies investigating the role of toll-like receptors in the developing brain will be emphasized. PMID:23097717

Hypoxia preconditioning increases survival and decreases expression of Toll-like receptor 4 in pulmonary artery endothelial cells exposed to lipopolysaccharide

PubMed Central

Nanchal, Rahul; Audi, Said; Konduri, G. Ganesh; Medhora, Meetha

2013-01-01

Abstract Pulmonary or systemic infections and hypoxemic respiratory failure are among the leading causes of admission to intensive care units, and these conditions frequently exist in sequence or in tandem. Inflammatory responses to infections are reproduced by lipopolysaccharide (LPS) engaging Toll-like receptor 4 (TLR4). Apoptosis is a hallmark of lung injury in sepsis. This study was conducted to determine whether preexposure to LPS or hypoxia modulated the survival of pulmonary artery endothelial cells (PAECs). We also investigated the role TLR4 receptor expression plays in apoptosis due to these conditions. Bovine PAECs were cultured in hypoxic or normoxic environments and treated with LPS. TLR4 antagonist TAK-242 was used to probe the role played by TLR4 receptors in cell survival. Cell apoptosis and survival were measured by caspase 3 activity and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) incorporation. TLR4 expression and tumor necrosis factor α (TNF-α) production were also determined. LPS increased caspase 3 activity in a TAK-242-sensitive manner and decreased MTT incorporation. Apoptosis was decreased in PAECs preconditioned with hypoxia prior to LPS exposure. LPS increased TNF-α production, and hypoxic preconditioning blunted it. Hypoxic preconditioning reduced LPS-induced TLR4 messenger RNA and TLR4 protein. TAK-242 decreased to baseline the LPS-stimulated expression of TLR4 messenger RNA regardless of environmental conditions. In contrast, LPS followed by hypoxia substantially increased apoptosis and cell death. In conclusion, protection from LPS-stimulated PAEC apoptosis by hypoxic preconditioning is attributable in part to reduction in TLR4 expression. If these signaling pathways apply to septic patients, they may account for differing sensitivities of individuals to acute lung injury depending on oxygen tensions in PAECs in vivo. PMID:24618542

Xenon Protects Against Septic Acute Kidney Injury via miR-21 Target Signaling Pathway.

PubMed

Jia, Ping; Teng, Jie; Zou, Jianzhou; Fang, Yi; Wu, Xie; Liang, Mingyu; Ding, Xiaoqiang

2015-07-01

Septic acute kidney injury is one of the most common and life-threatening complications in critically ill patients, and there is no approved effective treatment. We have shown xenon provides renoprotection against ischemia-reperfusion injury and nephrotoxicity in rodents via inhibiting apoptosis. Here, we studied the effects of xenon preconditioning on septic acute kidney injury and its mechanism. Experimental animal investigation. University research laboratory. Experiments were performed with male C57BL/6 mice, 10 weeks of age, weighing 20-25 g. We induced septic acute kidney injury by a single intraperitoneal injection of Escherichia coli lipopolysaccharide at a dose of 20 mg/kg. Mice were exposed for 2 hours to either 70% xenon or 70% nitrogen, 24 hours before the onset of septic acute kidney injury. In vivo knockdown of miR-21 was performed using locked nucleic acid-modified anti-miR, the role of miR-21 in renal protection conferred by the xenon preconditioning was examined, and miR-21 signaling pathways were analyzed. Xenon preconditioning provided morphologic and functional renoprotection, characterized by attenuation of renal tubular damage, apoptosis, and a reduction in inflammation. Furthermore, xenon treatment significantly upregulated the expression of miR-21 in kidney, suppressed proinflammatory factor programmed cell death protein 4 expression and nuclear factor-κB activity, and increased interleukin-10 production. Meanwhile, xenon preconditioning also suppressed the expression of proapoptotic protein phosphatase and tensin homolog deleted on chromosome 10, activating protein kinase B signaling pathway, subsequently increasing the expression of antiapoptotic B-cell lymphoma-2, and inhibiting caspase-3 activity. Knockdown of miR-21 upregulated its target effectors programmed cell death protein 4 and phosphatase and tensin homolog deleted on chromosome 10 expression, resulted in an increase in apoptosis, and exacerbated lipopolysaccharide-induced acute kidney injury. Our findings demonstrated that xenon preconditioning protected against lipopolysaccharide-induced acute kidney injury via activation of miR-21 target signaling pathways.

40 CFR 86.132-00 - Vehicle preconditioning.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 18 2011-07-01 2011-07-01 false Vehicle preconditioning. 86.132-00... (CONTINUED) CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND ENGINES Emission Regulations for 1977 and Later Model Year New Light-Duty Vehicles and New Light-Duty Trucks and New Otto-Cycle Complete...

40 CFR 86.132-96 - Vehicle preconditioning.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 19 2012-07-01 2012-07-01 false Vehicle preconditioning. 86.132-96... (CONTINUED) CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND ENGINES Emission Regulations for 1977 and Later Model Year New Light-Duty Vehicles and New Light-Duty Trucks and New Otto-Cycle Complete...

40 CFR 86.132-96 - Vehicle preconditioning.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 19 2014-07-01 2014-07-01 false Vehicle preconditioning. 86.132-96... (CONTINUED) CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND ENGINES Emission Regulations for 1977 and Later Model Year New Light-Duty Vehicles and New Light-Duty Trucks and New Otto-Cycle Complete...

40 CFR 86.132-00 - Vehicle preconditioning.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 19 2013-07-01 2013-07-01 false Vehicle preconditioning. 86.132-00... (CONTINUED) CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND ENGINES Emission Regulations for 1977 and Later Model Year New Light-Duty Vehicles and New Light-Duty Trucks and New Otto-Cycle Complete...

40 CFR 86.132-00 - Vehicle preconditioning.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 19 2014-07-01 2014-07-01 false Vehicle preconditioning. 86.132-00... (CONTINUED) CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND ENGINES Emission Regulations for 1977 and Later Model Year New Light-Duty Vehicles and New Light-Duty Trucks and New Otto-Cycle Complete...

40 CFR 86.132-00 - Vehicle preconditioning.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 19 2012-07-01 2012-07-01 false Vehicle preconditioning. 86.132-00... (CONTINUED) CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND ENGINES Emission Regulations for 1977 and Later Model Year New Light-Duty Vehicles and New Light-Duty Trucks and New Otto-Cycle Complete...

Low-Dose Ethanol Preconditioning Protects Against Oxygen-Glucose Deprivation/Reoxygenation-Induced Neuronal Injury By Activating Large Conductance, Ca2+-Activated K+ Channels In Vitro.

PubMed

Su, Fang; Guo, An-Chen; Li, Wei-Wei; Zhao, Yi-Long; Qu, Zheng-Yi; Wang, Yong-Jun; Wang, Qun; Zhu, Yu-Lan

2017-02-01

Increasing evidence suggests that low to moderate ethanol ingestion protects against the deleterious effects of subsequent ischemia/reperfusion; however, the underlying mechanism has not been elucidated. In the present study, we showed that expression of the neuronal large-conductance, Ca 2+ -activated K + channel (BK Ca ) α-subunit was upregulated in cultured neurons exposed to oxygen-glucose deprivation/reoxygenation (OGD/R) compared with controls. Preconditioning with low-dose ethanol (10 mmol/L) increased cell survival rate in neurons subjected to OGD/R, attenuated the OGD/R-induced elevation of cytosolic Ca 2+ levels, and reduced the number of apoptotic neurons. Western blots revealed that ethanol preconditioning upregulated expression of the anti-apoptotic protein Bcl-2 and downregulated the pro-apoptotic protein Bax. The protective effect of ethanol preconditioning was antagonized by a BK Ca channel inhibitor, paxilline. Inside-out patches in primary neurons also demonstrated the direct activation of the BK Ca channel by 10 mmol/L ethanol. The above results indicated that low-dose ethanol preconditioning exerts its neuroprotective effects by attenuating the elevation of cytosolic Ca 2+ and preventing neuronal apoptosis, and this is mediated by BK Ca channel activation.

Exercise Preconditioning Protects against Spinal Cord Injury in Rats by Upregulating Neuronal and Astroglial Heat Shock Protein 72

PubMed Central

Chang, Cheng-Kuei; Chou, Willy; Lin, Hung-Jung; Huang, Yi-Ching; Tang, Ling-Yu; Lin, Mao-Tsun; Chang, Ching-Ping

2014-01-01

The heat shock protein 72 (HSP 72) is a universal marker of stress protein whose expression can be induced by physical exercise. Here we report that, in a localized model of spinal cord injury (SCI), exercised rats (given pre-SCI exercise) had significantly higher levels of neuronal and astroglial HSP 72, a lower functional deficit, fewer spinal cord contusions, and fewer apoptotic cells than did non-exercised rats. pSUPER plasmid expressing HSP 72 small interfering RNA (SiRNA-HSP 72) was injected into the injured spinal cords. In addition to reducing neuronal and astroglial HSP 72, the (SiRNA-HSP 72) significantly attenuated the beneficial effects of exercise preconditioning in reducing functional deficits as well as spinal cord contusion and apoptosis. Because exercise preconditioning induces increased neuronal and astroglial levels of HSP 72 in the gray matter of normal spinal cord tissue, exercise preconditioning promoted functional recovery in rats after SCI by upregulating neuronal and astroglial HSP 72 in the gray matter of the injured spinal cord. We reveal an important function of neuronal and astroglial HSP 72 in protecting neuronal and astroglial apoptosis in the injured spinal cord. We conclude that HSP 72-mediated exercise preconditioning is a promising strategy for facilitating functional recovery from SCI. PMID:25334068

Quercetin nanoparticle complex attenuated diabetic nephropathy via regulating the expression level of ICAM-1 on endothelium

PubMed Central

Tong, Fei; Liu, Suhuan; Yan, Bing; Li, Xuejun; Ruan, Shiwei; Yang, Shuyu

2017-01-01

The purpose of the study was to reveal the therapeutic effect of quercetin (QUE) nanoparticle complex on diabetic nephropathy (DN) by regulating the expression of intercellular adhesion molecular-1 (ICAM-1) on endothelium as compared to free QUE. QUE 10 mg/kg as a single abdominal subcutaneous injection daily for 8 weeks continuously in diabetic rats and 10 mg/kg QUE nanoparticle complex as a single abdominal subcutaneous injection every 5 days, continuously administered for 8 weeks to diabetic rats. Blood and left kidneys were collected; pathological change of kidney, renal function, oxidative stress level, blood glucose level, serum lipid, urine protein, and albumin/creatinine ratio were measured; and neutrophil adhesion, ICAM-1 expression, and CD11b+ cells infiltration were observed. Both QUE and QUE nanoparticle complex preconditioning ameliorated the pathological damage of kidney and improved renal function, alleviated renal oxidative stress injury, restricted inflammatory cells infiltration, and downregulated the ICAM-1 expression as compared to DN group, while QUE nanoparticle complex significantly alleviated this effect. PMID:29123394

Studies on cerebral protection of digoxin against hypoxic-ischemic brain damage in neonatal rats.

PubMed

Peng, Kaiwei; Tan, Danfeng; He, Miao; Guo, Dandan; Huang, Juan; Wang, Xia; Liu, Chentao; Zheng, Xiangrong

2016-08-17

Hypoxic-ischemic brain damage (HIBD) is a major cause of neonatal acute deaths and chronic nervous system damage. Our present study was designed to investigate the possible neuroprotective effect of digoxin-induced pharmacological preconditioning after hypoxia-ischemia and underlying mechanisms. Neonatal rats were assigned randomly to control, HIBD, or HIBD+digoxin groups. Pharmacological preconditioning was induced by administration of digoxin 72 h before inducing HIBD by carotid occlusion+hypoxia. Behavioral assays, and neuropathological and apoptotic assessments were performed to examine the effects; the expression of Na/K ATPase was also assessed. Rats in the HIBD group showed deficiencies on the T-maze, radial water maze, and postural reflex tests, whereas the HIBD+digoxin group showed significant improvements on all behavioral tests. The rats treated with digoxin showed recovery of pathological conditions, increased number of neural cells and proliferative cells, and decreased number of apoptotic cells. Meanwhile, an increased expression level of Na/K ATPase was observed after digoxin preconditioning treatment. The preconditioning treatment of digoxin contributed toward an improved functional recovery and exerted a marked neuroprotective effect including promotion of cell proliferation and reduction of apoptosis after HIBD, and the neuroprotective action was likely associated with increased expression of Na/K ATPase.

Exercise training improves relaxation response and SOD-1 expression in aortic and mesenteric rings from high caloric diet-fed rats.

PubMed

de Moraes, Camila; Davel, Ana Paula Couto; Rossoni, Luciana Venturini; Antunes, Edson; Zanesco, Angelina

2008-05-29

Obesity has been associated with a variety of disease such as type II diabetes mellitus, arterial hypertension and atherosclerosis. Evidences have shown that exercise training promotes beneficial effects on these disorders, but the underlying mechanisms are not fully understood. The aim of this study was to investigate whether physical preconditioning prevents the deleterious effect of high caloric diet in vascular reactivity of rat aortic and mesenteric rings. Male Wistar rats were divided into sedentary (SD); trained (TR); sedentary diet (SDD) and trained diet (TRD) groups. Run training (RT) was performed in sessions of 60 min, 5 days/week for 12 weeks (70-80% VO2max). Triglycerides, glucose, insulin and nitrite/nitrate concentrations (NOx-) were measured. Concentration-response curves to acetylcholine (ACh) and sodium nitroprusside (SNP) were obtained. Expression of Cu/Zn superoxide dismutase (SOD-1) was assessed by Western blotting. High caloric diet increased triglycerides concentration (SDD: 216 +/- 25 mg/dl) and exercise training restored to the baseline value (TRD: 89 +/- 9 mg/dl). Physical preconditioning significantly reduced insulin levels in both groups (TR: 0.54 +/- 0.1 and TRD: 1.24 +/- 0.3 ng/ml) as compared to sedentary animals (SD: 0.87 +/- 0.1 and SDD: 2.57 +/- 0.3 ng/ml). On the other hand, glucose concentration was slightly increased by high caloric diet, and RT did not modify this parameter (SD: 126 +/- 6; TR: 140 +/- 8; SDD: 156 +/- 8 and TRD 153 +/- 9 mg/dl). Neither high caloric diet nor RT modified NOx- levels (SD: 27 +/- 4; TR: 28 +/- 6; SDD: 27 +/- 3 and TRD: 30 +/- 2 microM). Functional assays showed that high caloric diet impaired the relaxing response to ACh in mesenteric (about 13%), but not in aortic rings. RT improved the relaxing responses to ACh either in aortic (28%, for TR and 16%, to TRD groups) or mesenteric rings (10%, for TR and 17%, to TRD groups) that was accompanied by up-regulation of SOD-1 expression and reduction in triglycerides levels. The improvement in endothelial function by physical preconditioning in mesenteric and aortic arteries from high caloric fed-rats was directly related to an increase in NO bioavailability to the smooth muscle mostly due to SOD-1 up regulation.

In vivo inhibition of the mitochondrial H+-ATP synthase in neurons promotes metabolic preconditioning.

PubMed

Formentini, Laura; Pereira, Marta P; Sánchez-Cenizo, Laura; Santacatterina, Fulvio; Lucas, José J; Navarro, Carmen; Martínez-Serrano, Alberto; Cuezva, José M

2014-04-01

A key transducer in energy conservation and signaling cell death is the mitochondrial H(+)-ATP synthase. The expression of the ATPase inhibitory factor 1 (IF1) is a strategy used by cancer cells to inhibit the activity of the H(+)-ATP synthase to generate a ROS signal that switches on cellular programs of survival. We have generated a mouse model expressing a mutant of human IF1 in brain neurons to assess the role of the H(+)-ATP synthase in cell death in vivo. The expression of hIF1 inhibits the activity of oxidative phosphorylation and mediates the shift of neurons to an enhanced aerobic glycolysis. Metabolic reprogramming induces brain preconditioning affording protection against quinolinic acid-induced excitotoxicity. Mechanistically, preconditioning involves the activation of the Akt/p70S6K and PARP repair pathways and Bcl-xL protection from cell death. Overall, our findings provide the first in vivo evidence highlighting the H(+)-ATP synthase as a target to prevent neuronal cell death.

Fourier analysis of finite element preconditioned collocation schemes

NASA Technical Reports Server (NTRS)

Deville, Michel O.; Mund, Ernest H.

1990-01-01

The spectrum of the iteration operator of some finite element preconditioned Fourier collocation schemes is investigated. The first part of the paper analyses one-dimensional elliptic and hyperbolic model problems and the advection-diffusion equation. Analytical expressions of the eigenvalues are obtained with use of symbolic computation. The second part of the paper considers the set of one-dimensional differential equations resulting from Fourier analysis (in the tranverse direction) of the 2-D Stokes problem. All results agree with previous conclusions on the numerical efficiency of finite element preconditioning schemes.

Enhanced cell volume regulation: a key protective mechanism of ischemic preconditioning in rabbit ventricular myocytes.

PubMed

Diaz, Roberto J; Armstrong, Stephen C; Batthish, Michelle; Backx, Peter H; Ganote, Charles E; Wilson, Gregory J

2003-01-01

Accumulation of osmotically active metabolites, which create an osmotic gradient estimated at ~60 mOsM, and cell swelling are prominent features of ischemic myocardial cell death. This study tests the hypothesis that reduction of ischemic swelling by enhanced cell volume regulation is a key mechanism in the delay of ischemic myocardial cell death by ischemic preconditioning (IPC). Experimental protocols address whether: (i) IPC triggers a cell volume regulation mechanism that reduces cardiomyocyte swelling during subsequent index ischemia; (ii) this reduction in ischemic cell swelling is sufficient in magnitude to account for the IPC protection; (iii) the molecular mechanism that mediates IPC also mediates cell volume regulation. Two experimental models with rabbit ventricular myocytes were studied: freshly isolated pelleted myocytes and 48-h cultured myocytes. Myocytes were preconditioned either by distinct short simulated ischemia (SI)/simulated reperfusion protocols (IPC), or by subjecting myocytes to a pharmacological preconditioning (PPC) protocol (1 microM calyculin A, or 1 microM N(6)-2-(4-aminophenyl)ethyladenosine (APNEA), prior to subjecting them to either different durations of long SI or 30 min hypo-osmotic stress. Cell death (percent blue square myocytes) was monitored by trypan blue staining. Cell swelling was determined by either the bromododecane cell flotation assay (qualitative) or video/confocal microscopy (quantitative). Simulated ischemia induced myocyte swelling in both the models. In pelleted myocytes, IPC or PPC with either calyculin A or APNEA produced a marked reduction of ischemic cell swelling as determined by the cell floatation assay. In cultured myocytes, IPC substantially reduced ischemic cell swelling (P < 0.001). This IPC effect on ischemic cell swelling was related to an IPC and PPC (with APNEA) mediated triggering of cell volume regulatory decrease (RVD). IPC and APNEA also significantly (P < 0.001) reduced hypo-osmotic cell swelling. This IPC and APNEA effect was blocked by either adenosine receptor, PKC or Cl(-) channel inhibition. The osmolar equivalent for IPC protection approximated 50-60 mOsM, an osmotic gradient similar to the estimated ischemic osmotic load for preconditioned and non-preconditioned myocytes. The results suggest that cell volume regulation is a key mechanism that accounts for most of the IPC protection in cardiomyocytes.

Ischemic preconditioning modulates the expression of several genes, leading to the overproduction of IL-1Ra, iNOS, and Bcl-2 in a human model of liver ischemia-reperfusion.

PubMed

Barrier, Alain; Olaya, Natalia; Chiappini, Franck; Roser, François; Scatton, Olivier; Artus, Cédric; Franc, Brigitte; Dudoit, Sandrine; Flahault, Antoine; Debuire, Brigitte; Azoulay, Daniel; Lemoine, Antoinette

2005-10-01

Ischemia triggers an inflammatory response that precipitates cell death during reperfusion. Several studies have shown that tissues are protected by ischemic preconditioning (IP) consisting of 10 min of ischemia followed by 10 min of reperfusion just before ischemia. The molecular basis of this protective effect is poorly understood. We used cDNA arrays (20K) to compare global gene expression in liver biopsies from living human liver donors who underwent IP (n=7) or not (n=7) just before liver devascularization. Microarray data were analyzed using pairedt test with a type I error rate fixed at alpha = 2.5 10(6) (Bonferroni correction). We found that 60 genes were differentially expressed (36 over- and 24 underexpressed in preconditioning group). After IP, the most significantly overexpressed gene was IL-1Ra. This was confirmed by immunoblotting. Differentially expressed were genes involved in apoptosis (NOD2, ephrin-A1, and calpain) and in the carbohydrate metabolism. A significant increase in the amount of the anti-apoptotic protein Bcl-2 in preconditioned livers but no change in the cleavage of procaspase-3, -8, and -9 was observed. We also observed an increase in the amount in the inducible nitric oxide synthase. Therefore, the benefits of IP may be associated with the overproduction of IL-1Ra, Bcl-2, and NO countering the proinflammatory and proapoptotic effects generated during ischemia-reperfusion.

Role of decoy molecules in neuronal ischemic preconditioning

PubMed Central

Panneerselvam, Mathivadhani; Patel, Piyush M.; Roth, David M.; Kidd, Michael W.; Chin-Lee, Blake; Head, Brian P.; Niesman, Ingrid R.; Inoue, Satoki; Patel, Hemal H.; Davis, Daniel P.

2011-01-01

Decoy receptors bind with TNF related apoptosis inducing ligands (TRAIL) but do not contain the cytoplasmic domains necessary to transduce apoptotic signals. We hypothesized that decoy receptors may confer neuronal protection against lethal ischemia after ischemic preconditioning (IPC). Mixed cortical neurons were exposed to IPC one day prior to TRAIL treatment or lethal ischemia. IPC increased decoy receptor but reduced death receptor expression compared to lethal ischemia. IPC-induced increase in decoy receptor expression was reduced by prior treatment with CAPE, a nuclear factor-kappa B inhibitor (NFκB). Expression of decoy molecules, dependent on NFκB, may mediate neuronal survival induced by IPC. PMID:21315738

Ischemic Preconditioning Confers Epigenetic Repression of Mtor and Induction of Autophagy Through G9a-Dependent H3K9 Dimethylation.

PubMed

Gidlöf, Olof; Johnstone, Andrea L; Bader, Kerstin; Khomtchouk, Bohdan B; O'Reilly, Jiaqi J; Celik, Selvi; Van Booven, Derek J; Wahlestedt, Claes; Metzler, Bernhard; Erlinge, David

2016-12-22

Ischemic preconditioning (IPC) protects the heart from prolonged ischemic insult and reperfusion injury through a poorly understood mechanism. Post-translational modifications of histone residues can confer rapid and drastic switches in gene expression in response to various stimuli, including ischemia. The aim of this study was to investigate the effect of histone methylation in the response to cardiac ischemic preconditioning. We used cardiac biopsies from mice subjected to IPC to quantify global levels of 3 of the most well-studied histone methylation marks (H3K9me2, H3K27me3, and H3K4me3) with Western blot and found that H3K9me2 levels were significantly increased in the area at risk compared to remote myocardium. In order to assess which genes were affected by the increase in H3K9me2 levels, we performed ChIP-Seq and transcriptome profiling using microarray. Two hundred thirty-seven genes were both transcriptionally repressed and enriched in H3K9me2 in the area at risk of IPC mice. Of these, Mtor (Mechanistic target of rapamycin) was chosen for mechanistic studies. Knockdown of the major H3K9 methyltransferase G9a resulted in a significant decrease in H3K9me2 levels across Mtor, increased Mtor expression, as well as decreased autophagic activity in response to rapamycin and serum starvation. IPC confers an increase of H3K9me2 levels throughout the Mtor gene-a master regulator of cellular metabolism and a key player in the cardioprotective effect of IPC-leading to transcriptional repression via the methyltransferase G9a. The results of this study indicate that G9a has an important role in regulating cardiac autophagy and the cardioprotective effect of IPC. © 2016 The Authors and University of Miami Miller School of Medicine. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

Morphine preconditioning confers cardioprotection in doxorubicin-induced failing rat hearts via ERK/GSK-3β pathway independent of PI3K/Akt.

PubMed

He, Shu-Fang; Jin, Shi-Yun; Wu, Hao; Wang, Bin; Wu, Yun-Xiang; Zhang, Shu-Jie; Irwin, Michael G; Wong, Tak-Ming; Zhang, Ye

2015-11-01

Preconditioning against myocardial ischemia-reperfusion (I/R) injury can be suppressed in some pathological conditions. This study was designed to investigate whether morphine preconditioning (MPC) exerts cardioprotection in doxorubicin (DOX)-induced heart failure in rats and the mechanisms involved. Phosphatidylinositol-3 kinase/protein kinase B (PI3K/Akt), extracellular signal-regulated kinase (ERK) and glycogen synthase kinase (GSK)-3β pathways were examined. Normal and DOX-induced failing rat hearts were subjected to I/R injury using a Langendorff perfusion system with or without MPC or ischemic preconditioning (IPC). The PI3K inhibitor (wortmannin) or ERK inhibitor (PD98059) was infused before MPC. In normal hearts, both MPC and IPC significantly reduced infarct size and the rise in lactate dehydrogenase (LDH) level caused by I/R injury. Pretreatment with wortmannin or PD98059 abrogated the protective effects of MPC and suppressed the phosphorylation of Akt, ERK and GSK-3β. In failing rat hearts, however, MPC retained its cardioprotection while IPC did not. This protective effect was abolished by PD98059 but not wortmannin. MPC increased the level of p-ERK rather than p-Akt. The phosphorylation of GSK-3β induced by MPC was reversed by PD98059 only. IPC did not elevate the expression of p-ERK, p-Akt and p-GSK-3β in failing rat hearts. We conclude that MPC is cardioprotective in rats with DOX-induced heart failure while IPC is not. The effect of MPC appears to be mediated via the ERK/GSK-3β pathway independent of PI3K/Akt. Copyright © 2015 Elsevier Inc. All rights reserved.

Hypoxic preconditioning protects photoreceptors against light damage independently of hypoxia inducible transcription factors in rods.

PubMed

Kast, Brigitte; Schori, Christian; Grimm, Christian

2016-05-01

Hypoxic preconditioning protects photoreceptors against light-induced degeneration preserving retinal morphology and function. Although hypoxia inducible transcription factors 1 and 2 (HIF1, HIF2) are the main regulators of the hypoxic response, photoreceptor protection does not depend on HIF1 in rods. Here we used rod-specific Hif2a single and Hif1a;Hif2a double knockout mice to investigate the potential involvement of HIF2 in rods for protection after hypoxic preconditioning. To identify potential HIF2 target genes in rods we determined the retinal transcriptome of hypoxic control and rod-specific Hif2a knockouts by RNA sequencing. We show that rods do not need HIF2 for hypoxia-induced increased survival after light exposure. The transcriptomic analysis revealed a number of genes that are potentially regulated by HIF2 in rods; among those were Htra1, Timp3 and Hmox1, candidates that are interesting due to their connection to human degenerative diseases of the retina. We conclude that neither HIF1 nor HIF2 are required in photoreceptors for protection by hypoxic preconditioning. We hypothesize that HIF transcription factors may be needed in other cells to produce protective factors acting in a paracrine fashion on photoreceptor cells. Alternatively, hypoxic preconditioning induces a rod-intrinsic response that is independent of HIF transcription factors. Copyright © 2015 Elsevier Ltd. All rights reserved.

Acidic pre-conditioning suppresses apoptosis and increases expression of Bcl-xL in coronary endothelial cells under simulated ischaemia.

PubMed

Kumar, S; Reusch, H P; Ladilov, Y

2008-01-01

Ischaemic pre-conditioning has a powerful protective potential against ischaemia-induced cell death, and acidosis is an important feature of ischaemia and can lead to apoptosis. Here we tested whether pre-conditioning with acidosis, that is, acidic pre-conditioning (APC), may protect coronary endothelial cells (EC) against apoptosis induced by simulated ischaemia. For pre-conditioning, EC were exposed fo 40 min. to acidosis (pH 6.4) followed by a 14-hrs recovery period (pH 7.4) and finally treated for 2 hrs with simulated ischaemia (glucose-free anoxia at pH 6.4). Cells undergoing apoptosis were visualized by chromatin staining or by determination of caspase-3 activity Simulated ischaemia in untreated EC increased caspase-3 activity and the number of apoptotic cell (31.3 +/- 1.3%versus 3.9 +/- 0.6% in control). APC significantly reduced the rate of apoptosis (14.2 +/- 1.3%) and caspase-3 activity. Western blot analysis exploring the under lying mechanism leading to this protection revealed suppression of the endoplasmic reticulum- (reduced cleavage of caspase-12) and mitochondria-mediated (reduced cytochrome C release) pathways of apoptosis. These effects were associated with an over-expression of the anti-apoptotic protein Bcl-xL 14 hrs after APC, whereas no effect on the expression of Bcl-2, Bax, Bak, procaspase-12, reticulum-localized chaperones (GRP78, calreticulin), HSP70, HSP32 and HSP27 could be detected. Knock-down of Bcl-xL by siRNA-treatment prevented the protective effect of APC. In conclusion, short acidic pre-treatment can protect EC against ischaemic apoptosis. The mechanism of this protection consists of suppression of the endoplasmic reticulum- and mitochondria-mediated pathways. Over-expression of the anti apoptotic protein Bcl-xL is responsible for the increased resistance to apoptosis during ischaemic insult.

Endogenous Agmatine Induced by Ischemic Preconditioning Regulates Ischemic Tolerance Following Cerebral Ischemia

PubMed Central

Kim, Jae Hwan; Kim, Jae Young; Jung, Jin Young; Lee, Yong Woo; Lee, Won Taek; Huh, Seung Kon

2017-01-01

Ischemic preconditioning (IP) is one of the most important endogenous mechanisms that protect the cells against ischemia-reperfusion (I/R) injury. However, the exact molecular mechanisms remain unclear. In this study, we showed that changes in the level of agmatine were correlated with ischemic tolerance. Changes in brain edema, infarct volume, level of agmatine, and expression of arginine decarboxylase (ADC) and nitric oxide synthases (NOS; inducible NOS [iNOS] and neural NOS [nNOS]) were analyzed during I/R injury with or without IP in the rat brain. After cerebral ischemia, brain edema and infarct volume were significantly reduced in the IP group. The level of agmatine was increased before and during ischemic injury and remained elevated in the early reperfusion phase in the IP group compared to the experimental control (EC) group. During IP, the level of plasma agmatine was increased in the early phase of IP, but that of liver agmatine was abruptly decreased. However, the level of agmatine was definitely increased in the ipsilateral and contralateral hemisphere of brain during the IP. IP also increased the expression of ADC—the enzyme responsible for the synthesis of endogenous agmatine—before, during, and after ischemic injury. In addition, ischemic injury increased endogenous ADC expression in the EC group. The expression of nNOS was reduced in the I/R injured brain in the IP group. These results suggest that endogenous increased agmatine may be a component of the ischemic tolerance response that is induced by IP. Agmatine may have a pivotal role in endogenous ischemic tolerance. PMID:29302205

The peptide NDP-MSH induces phenotype changes in the heart that resemble ischemic preconditioning.

PubMed

Catania, Anna; Lonati, Caterina; Sordi, Andrea; Leonardi, Patrizia; Carlin, Andrea; Gatti, Stefano

2010-01-01

alpha-Melanocyte-stimulating hormone (alpha-MSH) is a pro-opiomelanocortin (POMC)-derived peptide that exerts multiple protective effects on host cells. Previous investigations showed that treatment with alpha-MSH or synthetic melanocortin agonists reduces heart damage in reperfusion injury and transplantation. The aim of this preclinical research was to determine whether melanocortin treatment induces preconditioning-like cardioprotection. In particular, the plan was to assess whether melanocortin administration causes phenotype changes similar to those induced by repetitive ischemic events. The idea was conceived because both ischemic preconditioning and melanocortin signaling largely depend on cAMP response element binding protein (CREB) phosphorylation. Rats received single i.v. injections of 750microg/kg of the alpha-MSH analogue Nle(4),DPhe(7)-alpha-MSH (NDP-MSH) or saline and were sacrificed at 0.5, 1, 3, or 5h. Western blot analysis showed that rat hearts expressed melanocortin 1 receptor (MC1R) protein. Treatment with NDP-MSH was associated with early and marked increase in interleukin 6 (IL-6) mRNA. This was followed by signal transducer and activator of transcription 3 (STAT3) phosphorylation and induction of suppressor of cytokine signaling 3 (SOCS3). There were no changes in expression of other cytokines of the IL-6 family. Expression of IL-10, IL-1beta, and TNF-alpha was likewise unaltered. In hearts of rats treated with NDP-MSH there was increased expression of the orphan nuclear receptor Nur77. The data indicate that NDP-MSH induces phenotype changes that closely resemble ischemic preconditioning and likely contribute to its established protection against reperfusion injury. In addition, the increased expression of Nur77 and SOCS3 could be part of a broader anti-inflammatory effect.

Ethanol preconditioning of rat cerebellar cultures targets NMDA receptors to the synapse and enhances peroxiredoxin 2 expression.

PubMed

Mitchell, Robert M; Tajuddin, Nuzhath; Campbell, Edward M; Neafsey, Edward J; Collins, Michael A

2016-07-01

Epidemiological studies indicate that light-moderate alcohol (ethanol) consumers tend to have reduced risks of cognitive impairment and progression to dementia during aging. Exploring possible mechanisms, we previously found that moderate ethanol preconditioning (MEP, 20-30mM) of rat brain cultures for several days instigated neuroprotection against β-amyloid peptides. Our biochemical evidence implicated the NMDA receptor (NMDAR) as a potential neuroprotective "sensor", specifically via synaptic NMDAR signaling. It remains unclear how ethanol modulates the receptor and its downstream targets to engender neuroprotection. Here we confirm with deconvolution microscopy that MEP of rat mixed cerebellar cultures robustly increases synaptic NMDAR localization. Phospho-activation of the non-receptor tyrosine kinases Src and Pyk2, known to be linked to synaptic NMDAR, is also demonstrated. Additionally, the preconditioning enhances levels of an antioxidant protein, peroxiredoxin 2 (Prx2), reported to be downstream of synaptic NMDAR signaling, and NMDAR antagonism with memantine (earlier found to abrogate MEP neuroprotection) blocks the Prx2 elevations. To further link Prx2 with antioxidant-based neuroprotection, we circumvented the ethanol preconditioning-NMDAR pathway by pharmacologically increasing Prx2 with the naturally-occurring cruciferous compound, 3H-1,2-dithiole-3-thione (D3T). Thus, D3T pretreatment elevated Prx2 expression to a similar extent as MEP, while concomitantly preventing β-amyloid neurotoxicity; D3T also protected the cultures from hydrogen peroxide toxicity. The findings support a mechanism that couples synaptic NMDAR signaling, Prx2 expression and augmented antioxidant defenses in ethanol preconditioning-induced neuroprotection. That this mechanism can be emulated by a cruciferous vegetable constituent suggests that such naturally-occurring "neutraceuticals" may be useful in therapy for oxidative stress-related dementias. Copyright © 2016 Elsevier B.V. All rights reserved.

Xenon Protects Against Septic Acute Kidney Injury via miR-21 Target Signaling Pathway*

PubMed Central

Jia, Ping; Teng, Jie; Zou, Jianzhou; Fang, Yi; Wu, Xie; Liang, Mingyu

2015-01-01

Objectives: Septic acute kidney injury is one of the most common and life-threatening complications in critically ill patients, and there is no approved effective treatment. We have shown xenon provides renoprotection against ischemia-reperfusion injury and nephrotoxicity in rodents via inhibiting apoptosis. Here, we studied the effects of xenon preconditioning on septic acute kidney injury and its mechanism. Design: Experimental animal investigation. Setting: University research laboratory. Subjects: Experiments were performed with male C57BL/6 mice, 10 weeks of age, weighing 20–25 g. Interventions: We induced septic acute kidney injury by a single intraperitoneal injection of Escherichia coli lipopolysaccharide at a dose of 20 mg/kg. Mice were exposed for 2 hours to either 70% xenon or 70% nitrogen, 24 hours before the onset of septic acute kidney injury. In vivo knockdown of miR-21 was performed using locked nucleic acid-modified anti-miR, the role of miR-21 in renal protection conferred by the xenon preconditioning was examined, and miR-21 signaling pathways were analyzed. Measurements and Main Results: Xenon preconditioning provided morphologic and functional renoprotection, characterized by attenuation of renal tubular damage, apoptosis, and a reduction in inflammation. Furthermore, xenon treatment significantly upregulated the expression of miR-21 in kidney, suppressed proinflammatory factor programmed cell death protein 4 expression and nuclear factor-κB activity, and increased interleukin-10 production. Meanwhile, xenon preconditioning also suppressed the expression of proapoptotic protein phosphatase and tensin homolog deleted on chromosome 10, activating protein kinase B signaling pathway, subsequently increasing the expression of antiapoptotic B-cell lymphoma-2, and inhibiting caspase-3 activity. Knockdown of miR-21 upregulated its target effectors programmed cell death protein 4 and phosphatase and tensin homolog deleted on chromosome 10 expression, resulted in an increase in apoptosis, and exacerbated lipopolysaccharide-induced acute kidney injury. Conclusion: Our findings demonstrated that xenon preconditioning protected against lipopolysaccharide-induced acute kidney injury via activation of miR-21 target signaling pathways. PMID:25844699

Flagellin preconditioning enhances the efficacy of mesenchymal stem cells in an irradiation-induced proctitis model.

PubMed

Linard, Christine; Strup-Perrot, Carine; Lacave-Lapalun, Jean-Victor; Benderitter, Marc

2016-09-01

The success of mesenchymal stem cell transplantation for proctitis depends not only on cell donors but also on host microenvironmental factors, which play a major role in conditioning mesenchymal stem cell immunosuppressive action and repair. This study sought to determine if flagellin, a TLR5 ligand, can enhance the mesenchymal stem cell treatment efficacy in radiation-induced proctitis. With the use of a colorectal model of 27 Gy irradiation in rats, we investigated and compared the effects on immune capacity and remodeling at 28 d after irradiation of the following: 1) systemic mesenchymal stem cell (5 × 10(6)) administration at d 7 after irradiation, 2) administration of flagellin at d 3 and systemic mesenchymal stem cell administration at d 7, and 3) in vitro preconditioning of mesenchymal stem cells with flagellin, 24 h before their administration on d 7. The mucosal CD8(+) T cell population was normalized after treatment with flagellin-preconditioned mesenchymal stem cells or flagellin plus mesenchymal stem cells, whereas mesenchymal stem cells alone did not alter the radiation-induced elevation of CD8(+) T cell frequency. Mesenchymal stem cell treatment returned the irradiation-elevated frequency of CD25(+) cells in the mucosa-to-control levels, whereas both flagellin-preconditioned mesenchymal stem cell and flagellin-plus-mesenchymal stem cell treatment each significantly increased not only CD25(+) cell frequency but also forkhead box p3 and IL-2Rα expression. Specifically, IL-10 was overexpressed after flagellin-preconditioned mesenchymal stem cell treatment. Analysis of collagen expression showed that the collagen type 1/collagen type 3 ratio, an indicator of wound-healing maturation, was low in the irradiated and mesenchymal stem cell-treated groups and returned to the normal level only after the flagellin-preconditioned mesenchymal stem cell treatment. This was associated with a reduction in myofibroblast accumulation. In a proctitis model, flagellin-preconditioned mesenchymal stem cells improved colonic immune capacity and enhanced tissue remodeling. © Society for Leukocyte Biology.

No influence of ischemic preconditioning on running economy.

PubMed

Kaur, Gungeet; Binger, Megan; Evans, Claire; Trachte, Tiffany; Van Guilder, Gary P

2017-02-01

Many of the potential performance-enhancing properties of ischemic preconditioning suggest that the oxygen cost for a given endurance exercise workload will be reduced, thereby improving the economy of locomotion. The aim of this study was to identify whether ischemic preconditioning improves exercise economy in recreational runners. A randomized sham-controlled crossover study was employed in which 18 adults (age 27 ± 7 years; BMI 24.6 ± 3 kg/m 2 ) completed two, incremental submaximal (65-85% VO 2max ) treadmill running protocols (3 × 5 min stages from 7.2-14.5 km/h) coupled with indirect calorimetry to assess running economy following ischemic preconditioning (3 × 5 min bilateral upper thigh ischemia) and sham control. Running economy was expressed as mlO 2 /kg/km and as the energy in kilocalories required to cover 1 km of horizontal distance (kcal/kg/km). Ischemic preconditioning did not influence steady-state heart rate, oxygen consumption, minute ventilation, respiratory exchange ratio, energy expenditure, and blood lactate. Likewise, running economy was similar (P = 0.647) between the sham (from 201.6 ± 17.7 to 204.0 ± 16.1 mlO 2 /kg/km) and ischemic preconditioning trials (from 202.8 ± 16.2 to 203.1 ± 15.6 mlO 2 /kg/km). There was no influence (P = 0.21) of ischemic preconditioning on running economy expressed as the caloric unit cost (from 0.96 ± 0.12 to 1.01 ± 0.11 kcal/kg/km) compared with sham (from 1.00 ± 0.10 to 1.00 ± 0.08 kcal/kg/km). The properties of ischemic preconditioning thought to affect exercise performance at vigorous to severe exercise intensities, which generate more extensive physiological challenge, are ineffective at submaximal workloads and, therefore, do not change running economy.

Eff ect of a single asenapine treatment on Fos expression in the brain catecholamine-synthesizing neurons: impact of a chronic mild stress preconditioning.

PubMed

Osacka, J; Horvathova, L; Majercikova, Z; Kiss, Alexander

2017-04-25

Fos protein expression in catecholamine-synthesizing neurons of the substantia nigra (SN) pars compacta (SNC, A8), pars reticulata (SNR, A9), and pars lateralis (SNL), the ventral tegmental area (VTA, A10), the locus coeruleus (LC, A6) and subcoeruleus (sLC), the ventrolateral pons (PON-A5), the nucleus of the solitary tract (NTS-A2), the area postrema (AP), and the ventrolateral medulla (VLM-A1) was quantitatively evaluated aft er a single administration of asenapine (ASE) (designated for schizophrenia treatment) in male Wistar rats preconditioned with a chronic unpredictable variable mild stress (CMS) for 21 days. Th e aim of the present study was to reveal whether a single ASE treatment may 1) activate Fos expression in the brain areas selected; 2) activate tyrosine hydroxylase (TH)-synthesizing cells displaying Fos presence; and 3) be modulated by CMS preconditioning. Control (CON), ASE, CMS, and CMS+ASE groups were used. CMS included restraint, social isolation, crowding, swimming, and cold. Th e ASE and CMS+ASE groups received a single dose of ASE (0.3 mg/kg, s.c.) and CON and CMS saline (300 μl/rat, s.c.). The animals were sacrificed 90 min aft er the treatments. Fos protein and TH-labeled immunoreactive perikarya were analyzed on double labeled histological sections and enumerated on captured pictures using combined light and fluorescence microscope illumination. Saline or CMS alone did not promote Fos expression in any of the structures investigated. ASE alone or in combination with CMS elicited Fos expression in two parts of the SN (SNC, SNR) and the VTA. Aside from some cells in the central gray tegmental nuclei adjacent to LC, where a small number of Fos profiles occurred, none or negligible Fos occurrence was detected in the other structures investigated including the LC and sLC, PON-A5, NTS-A2, AP, and VLM-A1. CMS preconditioning did not infl uence the level of Fos induction in the SN and VTA elicited by ASE administration. Similarly, the ratio between the amount of free Fos and Fos colocalized with TH was not aff ected by stress preconditioning in the SNC, SNR, and the VTA. Th e present study provides an anatomical/functional knowledge about the nature of the acute ASE treatment on the catecholamine-synthesizing neurons activity in certain brain structures and their missing interplay with the CMS preconditioning.

Ischemic preconditioning provides both acute and delayed protection against renal ischemia and reperfusion injury in mice.

PubMed

Joo, Jin Deok; Kim, Mihwa; D'Agati, Vivette D; Lee, H Thomas

2006-11-01

Acute as well as delayed ischemic preconditioning (IPC) provides protection against cardiac and neuronal ischemia reperfusion (IR) injury. This study determined whether delayed preconditioning occurs in the kidney and further elucidated the mechanisms of renal IPC in mice. Mice were subjected to IPC (four cycles of 5 min of ischemia and reperfusion) and then to 30 min of renal ischemia either 15 min (acute IPC) or 24 h (delayed IPC) later. Both acute and delayed renal IPC provided powerful protection against renal IR injury. Inhibition of Akt but not extracellular signal-regulated kinase phosphorylation prevented the protection that was afforded by acute IPC. Neither extracellular signal-regulated kinase nor Akt inhibition prevented protection that was afforded by delayed renal IPC. Pretreatment with an antioxidant, N-(2-mercaptopropionyl)-glycine, to scavenge free radicals prevented the protection that was provided by acute but not delayed renal IPC. Inhibition of protein kinase C or pertussis toxin-sensitive G-proteins attenuated protection from both acute and delayed renal IPC. Delayed renal IPC increased inducible nitric oxide synthase (iNOS) as well as heat-shock protein 27 synthesis, and the renal protective effects of delayed preconditioning were attenuated by a selective inhibitor of iNOS (l-N(6)[1-iminoethyl]lysine). Moreover, delayed IPC was not observed in iNOS knockout mice. Both acute and delayed IPC were independent of A(1) adenosine receptors (AR) as a selective A(1)AR antagonist failed to block preconditioning and acute and delayed preconditioning occurred in mice that lacked A(1)AR. Therefore, this study demonstrated that acute or delayed IPC provides renal protection against IR injury in mice but involves distinct signaling pathways.

Eye-Specific Gene Expression following Embryonic Ethanol Exposure in Zebrafish: Roles for Heat Shock Factor 1

PubMed Central

Kashyap, Bhavani; Pegorsch, Laurel; Frey, Ruth A.; Sun, Chi; Shelden, Eric A.; Stenkamp, Deborah L.

2014-01-01

The mechanisms through which ethanol exposure results in developmental defects remain unclear. We used the zebrafish model to elucidate eye-specific mechanisms that underlie ethanol-mediated microphthalmia (reduced eye size), through time-series microarray analysis of gene expression within eyes of embryos exposed to 1.5% ethanol. 62 genes were differentially expressed (DE) in ethanol-treated as compared to control eyes sampled during retinal neurogenesis (24-48 hours post-fertilization). The EDGE (extraction of differential gene expression) algorithm identified >3000 genes DE over developmental time in ethanol-exposed eyes as compared to controls. The DE lists included several genes indicating a mis-regulated cellular stress response due to ethanol exposure. Combined treatment with sub-threshold levels of ethanol and a morpholino targeting heat shock factor 1 mRNA resulted in microphthalmia, suggesting convergent molecular pathways. Thermal preconditioning partially prevented ethanol-mediated microphthalmia while maintaining Hsf-1 expression. These data suggest roles for reduced Hsf-1 in mediating microphthalmic effects of embryonic ethanol exposure. PMID:24355176

Role of Phosphatidylinositol-3 Kinase Pathway in NMDA Preconditioning: Different Mechanisms for Seizures and Hippocampal Neuronal Degeneration Induced by Quinolinic Acid.

PubMed

Constantino, Leandra C; Binder, Luisa B; Vandresen-Filho, Samuel; Viola, Giordano G; Ludka, Fabiana K; Lopes, Mark W; Leal, Rodrigo B; Tasca, Carla I

2018-04-20

N-methyl D-aspartate (NMDA) preconditioning is evoked by the administration of a subtoxic dose of NMDA and is protective against neuronal excitotoxicity. This effect may involve a diversity of targets and cell signaling cascades associated to neuroprotection. Phosphatidylinositol-3 kinase/protein kinase B (PI3K/Akt) and mitogen-activated protein kinases (MAPKs) such as extracellular regulated protein kinase 1/2 (ERK1/2) and p38 MAPK pathways play a major role in neuroprotective mechanisms. However, their involvement in NMDA preconditioning was not yet fully investigated. The present study aimed to evaluate the effect of NMDA preconditioning on PI3K/Akt, ERK1/2, and p38 MAPK pathways in the hippocampus of mice and characterize the involvement of PI3K on NMDA preconditioning-evoked prevention of seizures and hippocampal cell damage induced by quinolinic acid (QA). Thus, mice received wortmannin (a PI3K inhibitor) and 15 min later a subconvulsant dose of NMDA (preconditioning) or saline. After 24 h of this treatment, an intracerebroventricular QA infusion was administered. Phosphorylation levels and total content of Akt, glycogen synthase protein kinase-3β (GSK-3β), ERK1/2, and p38 MAPK were not altered after 24 h of NMDA preconditioning with or without wortmmanin pretreatment. Moreover, after QA administration, behavioral seizures, hippocampal neuronal degeneration, and Akt activation were evaluated. Inhibition of PI3K pathway was effective in abolishing the protective effect of NMDA preconditioning against QA-induced seizures, but did not modify neuronal protection promoted by preconditioning as evaluated by Fluoro-Jade B staining. The study confirms that PI3K participates in the mechanism of protection induced by NMDA preconditioning against QA-induced seizures. Conversely, NMDA preconditioning-evoked protection against neuronal degeneration is not altered by PI3K signaling pathway inhibition. These results point to differential mechanisms regarding protection against a behavioral and cellular manifestation of neural damage.

Controlled hydrostatic pressure stress downregulates the expression of ribosomal genes in preimplantation embryos: a possible protection mechanism?

PubMed

Bock, I; Raveh-Amit, H; Losonczi, E; Carstea, A C; Feher, A; Mashayekhi, K; Matyas, S; Dinnyes, A; Pribenszky, C

2016-04-01

The efficiency of various assisted reproductive techniques can be improved by preconditioning the gametes and embryos with sublethal hydrostatic pressure treatment. However, the underlying molecular mechanism responsible for this protective effect remains unknown and requires further investigation. Here, we studied the effect of optimised hydrostatic pressure treatment on the global gene expression of mouse oocytes after embryonic genome activation. Based on a gene expression microarray analysis, a significant effect of treatment was observed in 4-cell embryos derived from treated oocytes, revealing a transcriptional footprint of hydrostatic pressure-affected genes. Functional analysis identified numerous genes involved in protein synthesis that were downregulated in 4-cell embryos in response to hydrostatic pressure treatment, suggesting that regulation of translation has a major role in optimised hydrostatic pressure-induced stress tolerance. We present a comprehensive microarray analysis and further delineate a potential mechanism responsible for the protective effect of hydrostatic pressure treatment.

The effect of brain death in rat steatotic and non-steatotic liver transplantation with previous ischemic preconditioning.

PubMed

Jiménez-Castro, Mónica B; Meroño, Noelia; Mendes-Braz, Mariana; Gracia-Sancho, Jordi; Martínez-Carreres, Laia; Cornide-Petronio, Maria Eugenia; Casillas-Ramirez, Araní; Rodés, Juan; Peralta, Carmen

2015-01-01

Most liver grafts undergoing transplantation derive from brain dead donors, which may also show hepatic steatosis, being both characteristic risk factors in liver transplantation. Ischemic preconditioning shows benefits when applied in non-brain dead clinical situations like hepatectomies, whereas it has been less promising in the transplantation from brain dead patients. This study examined how brain death affects preconditioned steatotic and non-steatotic liver grafts undergoing transplantation. Steatotic and non-steatotic grafts from non-brain dead and brain dead-donors were cold stored for 6h and then transplanted. After 2, 4, and 16 h of reperfusion, hepatic damage was analysed. In addition, two therapeutic strategies, ischemic preconditioning and/or acetylcholine pre-treatment, and their underlying mechanisms were characterized. Preconditioning benefits in non-brain dead donors were associated with nitric oxide and acetylcholine generation. In brain dead donors, preconditioning generated nitric oxide but did not promote acetylcholine upregulation, and this resulted in inflammation and damage. Acetylcholine treatment in brain dead donors, through PKC, increased antioxidants and reduced lipid peroxidation, nitrotyrosines and neutrophil accumulation, altogether protecting against damage. The combination of acetylcholine and preconditioning conferred stronger protection against damage, oxidative stress and neutrophil accumulation than acetylcholine treatment alone. These superior beneficial effects were due to a selective preconditioning-mediated generation of nitric oxide and regulation of PPAR and TLR4 pathways, which were not observed when acetylcholine was administered alone. Our findings propose the combination of acetylcholine+preconditioning as a feasible and highly protective strategy to reduce the adverse effects of brain death and to ultimately improve liver graft quality. Copyright © 2014 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.

Sevoflurane postconditioning improves myocardial mitochondrial respiratory function and reduces myocardial ischemia-reperfusion injury by up-regulating HIF-1

PubMed Central

Yang, Long; Xie, Peng; Wu, Jianjiang; Yu, Jin; Yu, Tian; Wang, Haiying; Wang, Jiang; Xia, Zhengyuan; Zheng, Hong

2016-01-01

Background: Sevoflurane postconditioning (SPostC) can exert myocardial protective effects similar to ischemic preconditioning. However, the exact myocardial protection mechanism by SPostC is unclear. Studies indicate that hypoxia-inducible factor-1 (HIF-1) maintains cellular respiration homeostasis by regulating mitochondrial respiratory chain enzyme activity under hypoxic conditions. This study investigated whether SPostC could regulate the expression of myocardial HIF-1α and to improve mitochondrial respiratory function, thereby relieving myocardial ischemia-reperfusion injury in rats. Methods: The myocardial ischemia-reperfusion rat model was established using the Langendorff isolated heart perfusion apparatus. Additionally, postconditioning was performed using sevoflurane alone or in combination with the HIF-1α inhibitor 2-methoxyestradiol (2ME2). The changes in hemodynamic parameters, HIF-1α protein expression levels, mitochondrial respiratory function and enzyme activity, mitochondrial reactive oxygen species (ROS) production rates, and mitochondrial ultrastructure were measured or observed. Results: Compared to the ischemia-reperfusion (I/R) group, HIF-1α expression in the SPostC group was significantly up-regulated. Additionally, cardiac function indicators, mitochondrial state 3 respiratory rate, respiratory control ratio (RCR), cytochrome C oxidase (CcO), NADH oxidase (NADHO), and succinate oxidase (SUCO) activities, mitochondrial ROS production rate, and mitochondrial ultrastructure were significantly better than those in the I/R group. However, these advantages were completely reversed by the HIF-1α specific inhibitor 2ME2 (P<0.05). Conclusion: The myocardial protective function of SPostC might be associated with the improvement of mitochondrial respiratory function after up-regulation of HIF-1α expression. PMID:27830025

Sevoflurane postconditioning improves myocardial mitochondrial respiratory function and reduces myocardial ischemia-reperfusion injury by up-regulating HIF-1.

PubMed

Yang, Long; Xie, Peng; Wu, Jianjiang; Yu, Jin; Yu, Tian; Wang, Haiying; Wang, Jiang; Xia, Zhengyuan; Zheng, Hong

2016-01-01

Sevoflurane postconditioning (SPostC) can exert myocardial protective effects similar to ischemic preconditioning. However, the exact myocardial protection mechanism by SPostC is unclear. Studies indicate that hypoxia-inducible factor-1 (HIF-1) maintains cellular respiration homeostasis by regulating mitochondrial respiratory chain enzyme activity under hypoxic conditions. This study investigated whether SPostC could regulate the expression of myocardial HIF-1α and to improve mitochondrial respiratory function, thereby relieving myocardial ischemia-reperfusion injury in rats. The myocardial ischemia-reperfusion rat model was established using the Langendorff isolated heart perfusion apparatus. Additionally, postconditioning was performed using sevoflurane alone or in combination with the HIF-1α inhibitor 2-methoxyestradiol (2ME2). The changes in hemodynamic parameters, HIF-1α protein expression levels, mitochondrial respiratory function and enzyme activity, mitochondrial reactive oxygen species (ROS) production rates, and mitochondrial ultrastructure were measured or observed. Compared to the ischemia-reperfusion (I/R) group, HIF-1α expression in the SPostC group was significantly up-regulated. Additionally, cardiac function indicators, mitochondrial state 3 respiratory rate, respiratory control ratio (RCR), cytochrome C oxidase (C c O), NADH oxidase (NADHO), and succinate oxidase (SUCO) activities, mitochondrial ROS production rate, and mitochondrial ultrastructure were significantly better than those in the I/R group. However, these advantages were completely reversed by the HIF-1α specific inhibitor 2ME2 ( P <0.05). The myocardial protective function of SPostC might be associated with the improvement of mitochondrial respiratory function after up-regulation of HIF-1α expression.

Effects of High Hydrostatic Pressure on Expression Profiles of In Vitro Produced Vitrified Bovine Blastocysts

PubMed Central

Jiang, Zongliang; Harrington, Patrick; Zhang, Ming; Marjani, Sadie L.; Park, Joonghoon; Kuo, Lynn; Pribenszky, Csaba; Tian, Xiuchun (Cindy)

2016-01-01

High hydrostatic pressure (HHP) has been used to pre-condition embryos before essential, yet potentially detrimental procedures such as cryopreservation. However, the mechanisms for HHP are poorly understood. We treated bovine blastocysts with three different HHP (40, 60 and 80 MPa) in combination with three recovery periods (0, 1 h, 2 h post HHP). Re-expansion rates were significantly higher at 40 and 60 but lower at 80 MPa after vitrification-warming in the treated groups than controls. Microarray analysis revealed 399 differentially expressed transcripts, representing 254 unique genes, among different groups. Gene ontology analysis indicated that HHP at 40 and 60 MPa promoted embryo competence through down-regulation of genes in cell death and apoptosis, and up-regulation of genes in RNA processing, cellular growth and proliferation. In contrast, 80 MPa up-regulated genes in apoptosis, and down-regulated protein folding and cell cycle-related genes. Moreover, gene expression was also influenced by the length of the recovery time after HHP. The significantly over-represented categories were apoptosis and cell death in the 1 h group, and protein folding, response to unfolded protein and cell cycle in the 2 h group compared to 0 h. Taken together, HHP promotes competence of vitrified bovine blastocysts through modest transcriptional changes. PMID:26883277

Ischemic preconditioning enhances autophagy but suppresses autophagic cell death in rat spinal neurons following ischemia-reperfusion.

PubMed

Fan, Jin; Zhang, Zitao; Chao, Xie; Gu, Jun; Cai, Weihua; Zhou, Wei; Yin, Guoyong; Li, Qingqing

2014-05-08

Autophagy serves to eliminate damaged proteins and organelles under normal physiological conditions and can be accelerated by pathological stress, possibly as a cytoprotective mechanism. Brief periods of ischemia (ischemic preconditioning or IPC) can reduce neuronal death in response to subsequent severe ischemic insults. Ischemic preconditioning also induces autophagy, but the contribution of autophagy to IPC-associated neuroprotection remains unclear. We investigated the contribution of autophagy to IPC-mediated neuroprotection in rats subjected to ischemic spinal cord injury. Fifty adult rats were randomly assigned to either (1) a sham group receiving anesthesia and surgical preparation (n=5), (2) an ischemia/reperfusion (I/R) group (n=20) subjected to 0.5 h ischemia followed by 3, 6, 12, or 24 h reperfusion, (3) an IPC group receiving three cycles of 5 min ischemia followed by 5 min of reperfusion (n=5), or (4) an IPC+I/R group (n=20). Hematoxylin-eosin (HE) and immunohistochemical staining were performed to evaluate spinal neuron survival in the four treatment groups. Autophagic activity was investigated by electron microscopy and by immunohistochemical and Western blot analyses of the autophagosome marker LC3-II and the autophagy-associated BH3 protein Beclin-1. Changes in Bcl-2/Beclin-1 complex association and Bcl-2 phosphorylation (p-Bcl-2) were examined by co-immunoprecipitation and Western blot analyses. In the I/R group, LC3-II was significantly elevated after 3h of reperfusion, but declined significantly by 24 h. At 24 h, I/R rats exhibited extensive spinal damage and decreased neuronal survival. In the IPC+IR group, neuronal death was reduced and expression of LC3-II sustained throughout the 24 h reperfusion period. In the I/R group, expression of (inactive) p-Bcl-2(Ser70) was increased significantly during reperfusion and was accompanied by dissociation of the Bcl-2/Beclin-1 complex and increased Beclin-1 expression. Preconditioning inhibited these changes in p-Bcl-2, Beclin-1, and Bcl-2/Beclin-1 complex expression. Ischemic preconditioning appears to sustain the beneficial effects of autophagic lysosomal degradation during I/R while inhibiting autophagic cell death. Copyright © 2014 Elsevier B.V. All rights reserved.

Protection of Hippocampal CA1 Neurons Against Ischemia/Reperfusion Injury by Exercise Preconditioning via Modulation of Bax/Bcl-2 Ratio and Prevention of Caspase-3 Activation.

PubMed

Aboutaleb, Nahid; Shamsaei, Nabi; Rajabi, Hamid; Khaksari, Mehdi; Erfani, Sohaila; Nikbakht, Farnaz; Motamedi, Pezhman; Shahbazi, Ali

2016-01-01

Ischemia leads to loss of neurons by apoptosis in specific brain regions, especially in the hippocampus. The purpose of this study was investigating the effects of exercise preconditioning on expression of Bax, Bcl-2, and caspase-3 proteins in hippocampal CA1 neurons after induction of cerebral ischemia. Male rats weighing 260-300 g were randomly allocated into three groups (sham, exercise, and ischemia). The rats in exercise group were trained to run on a treadmill 5 days a week for 4 weeks. Ischemia was induced by the occlusion of both common carotid arteries (CCAs) for 20 min. Levels of expression of Bax, Bcl-2, and caspase-3 proteins in CA1 area of hippocampus were determined by immunohistochemical staining . The number of active caspase-3-positive neurons in CA1 area were significantly increased in ischemia group, compared to sham-operated group (P<0.001), and exercise preconditioning significantly reduced the ischemia/reperfusion-induced caspase-3 activation, compared to the ischemia group (P<0.05). Also, results indicated a significant increase in Bax/Bcl-2 ratio in ischemia group, compared to sham-operated group (P<0.001). This study indicated that exercise has a neuroprotective effects against cerebral ischemia when used as preconditioning stimuli.

Preconditioning crush increases the survival rate of motor neurons after spinal root avulsion

PubMed Central

Li, Lin; Zuo, Yizhi; He, Jianwen

2014-01-01

In a previous study, heat shock protein 27 was persistently upregulated in ventral motor neurons following nerve root avulsion or crush. Here, we examined whether the upregulation of heat shock protein 27 would increase the survival rate of motor neurons. Rats were divided into two groups: an avulsion-only group (avulsion of the L4 lumbar nerve root only) and a crush-avulsion group (the L4 lumbar nerve root was crushed 1 week prior to the avulsion). Immunofluorescent staining revealed that the survival rate of motor neurons was significantly greater in the crush-avulsion group than in the avulsion-only group, and this difference remained for at least 5 weeks after avulsion. The higher neuronal survival rate may be explained by the upregulation of heat shock protein 27 expression in motor neurons in the crush-avulsion group. Furthermore, preconditioning crush greatly attenuated the expression of nitric oxide synthase in the motor neurons. Our findings indicate that the neuroprotective action of preconditioning crush is mediated through the upregulation of heat shock protein 27 expression and the attenuation of neuronal nitric oxide synthase upregulation following avulsion. PMID:25206852

Silencing heat shock factor 1 by small interfering RNA abrogates heat shock-induced cardioprotection against ischemia-reperfusion injury in mice.

PubMed

Yin, Chang; Xi, Lei; Wang, Xiaoyin; Eapen, Mareen; Kukreja, Rakesh C

2005-10-01

Induction of heat shock factor 1 (HSF1) is known to associate with cellular response to divergent pathophysiological stresses including whole body hyperthermia (WBH) and ischemia-reperfusion. However, a direct cause-effect relationship between HSF1 activation and cytoprotection induced by myocardial preconditioning has not been conclusively established, mainly due to the limitations of available experiment tools. In the present studies, we used a novel approach to block HSF1 with small interfering RNA (siRNA) technique in vivo. Male adult ICR mice were treated intraperitoneally with amine (vehicle) or siRNA specific to HSF1 (siRNA-HSF1). Three days later, WBH preconditioning protocol (rectal temperature 42 degrees C for 15 min) was applied to these mice under light anesthesia. WBH preconditioning resulted in 2.7-fold and 3.4-fold increase in cardiac HSF1 mRNA and protein expression respectively 2 hours after WBH, which was inhibited in the siRNA-treated mice. The silencing effect of siRNA on HSF1 was associated with complete loss of the infarct- limiting protection by WBH preconditioning after 48 hours. Pretreatment with siRNA-HSF1 had no effect on infarct size in the sham control animals as compared with the amine-treated group. DNA micro-array analysis revealed that siRNA-HSF1 caused a general inhibition on multiple members of HSP family, except Hsp32, Hsp47 and Hsp60. In addition, the silencing effect of siRNA on HSF1 and HSPs gene expression was transient and its inhibitory effect disappeared by 10 days after treatment. siRNA-HSF1 also impaired the thermotolerance of the heat shocked mice as indicated by higher mortality following WBH. For the first time, we have applied siRNA technique in the field of myocardial preconditioning to demonstrate HSF1 activation as an essential step in WBH preconditioning against cardiac ischemia-reperfusion injury.

Ischemic preconditioning fails to confer additional protection against ischemia-reperfusion injury in the hypothyroid rat heart.

PubMed

Mourouzis, I; Dimopoulos, A; Saranteas, T; Tsinarakis, N; Livadarou, E; Spanou, D; Kokkinos, A D; Xinaris, C; Pantos, C; Cokkinos, D V

2009-01-01

There is accumulating evidence showing that ischemic preconditioning (PC) may lose its cardioprotective effect in the diseased states. The present study investigated whether PC can be effective in hypothyroidism, a clinical condition which is common and often accompanies cardiac diseases such as heart failure and myocardial infarction. Hypothyroidism was induced in rats by 3-week administration of 6n-propyl-2-thiouracil in water (0.05 %). Normal and hypothyroid hearts (HYPO) were perfused in Langendorff mode and subjected to 20 min of zero-flow global ischemia and 45 min of reperfusion. A preconditioning protocol (PC) was also applied prior to ischemia. HYPO hearts had significantly improved post-ischemic recovery of left ventricular developed pressure, end-diastolic pressure and reduced lactate dehydrogenase release. Furthermore, phospho-JNK and p38 MAPK levels after ischemia and reperfusion were 4.0 and 3.0 fold lower in HYPO as compared to normal hearts (P<0.05). A different response to PC was observed in normal than in HYPO hearts. PC improved the post-ischemic recovery of function and reduced the extent of injury in normal hearts but had no additional effect on the hypothyroid hearts. This response, in the preconditioned normal hearts, resulted in 2.5 and 1.8 fold smaller expression of the phospho-JNK and phospho-p38 MAPK levels at the end of reperfusion, as compared to non-PC hearts (P<0.05), while in HYPO hearts, no additional reduction in the phosphorylation of these kinases was observed after PC. Hypothyroid hearts appear to be tolerant to ischemia-reperfusion injury. This response may be, at least in part, due to the down-regulation of ischemia-reperfusion induced activation of JNKs and p38 MAPK kinases. PC is not associated with further reduction in the activation of these kinases in the hypothyroid hearts and fails to confer added protection in those hearts.

Modeling Dynamic Regulatory Processes in Stroke.

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

McDermott, Jason E.; Jarman, Kenneth D.; Taylor, Ronald C.

2012-10-11

The ability to examine in silico the behavior of biological systems can greatly accelerate the pace of discovery in disease pathologies, such as stroke, where in vivo experimentation is lengthy and costly. In this paper we describe an approach to in silico examination of blood genomic responses to neuroprotective agents and subsequent stroke through the development of dynamic models of the regulatory processes observed in the experimental gene expression data. First, we identified functional gene clusters from these data. Next, we derived ordinary differential equations (ODEs) relating regulators and functional clusters from the data. These ODEs were used to developmore » dynamic models that simulate the expression of regulated functional clusters using system dynamics as the modeling paradigm. The dynamic model has the considerable advantage of only requiring an initial starting state, and does not require measurement of regulatory influences at each time point in order to make accurate predictions. The manipulation of input model parameters, such as changing the magnitude of gene expression, made it possible to assess the behavior of the networks through time under varying conditions. We report that an optimized dynamic model can provide accurate predictions of overall system behavior under several different preconditioning paradigms.« less

EXPOSURE METHOD CONSIDERATIONS FOR MEASURING VITELLOGENIN EXPRESSION IN LARVAL AND MALE FATHEAD MINNOWS (PIMEPHALES PROMELAS)

EPA Science Inventory

Our laboratory has developed methods for measuring the expression of the vitellogenin (Vg) gene in larval and adult male fathead minnows. During this development we found several conditions that affect background Vg levels and we observed preconditions for the expression of this...

Involvement of adenosine and standardization of aqueous extract of garlic (Allium sativum Linn.) on cardioprotective and cardiodepressant properties in ischemic preconditioning and myocardial ischemia-reperfusion induced cardiac injury

PubMed Central

Sharma, Ashish Kumar; Munajjam, Arshee; Vaishnav, Bhawna; Sharma, Richa; Sharma, Ashok; Kishore, Kunal; Sharma, Akash; Sharma, Divya; Kumari, Rita; Tiwari, Ashish; Singh, Santosh Kumar; Gaur, Samir; Jatav, Vijay Singh; Srinivasan, Barthu Parthi; Agarwal, Shyam Sunder

2012-01-01

The present study investigated the effect of garlic (Allium sativum Linn.) aqueous extracts on ischemic preconditioning and ischemia-reperfusion induced cardiac injury, as well as adenosine involvement in ischemic preconditioning and garlic extract induced cardioprotection. A model of ischemia-reperfusion injury was established using Langendorff apparatus. Aqueous extract of garlic dose was standardized (0.5%, 0.4%, 0.3%, 0.2%, 0.1%, 0.07%, 0.05%, 0.03%, 0.01%), and the 0.05% dose was found to be the most effective. Higher doses (more than 0.05%) were highly toxic, causing arrhythmia and cardiodepression, whereas the lower doses were ineffective. Garlic exaggerated the cardioprotective effect of ischemic preconditioning. The cardioprotective effect of ischemic preconditioning and garlic cardioprotection was significantly attenuated by theophylline (1,000 µmol/L) and 8-SPT (10 mg/kg, i.p.) and expressed by increased myocardial infarct size, increased LDH level, and reduced nitrite and adenosine levels. These findings suggest that adenosine is involved in the pharmacological and molecular mechanism of garlic induced cardioprotection and mediated by the modulation of nitric oxide. PMID:23554727

Ginkgolide B preconditioning protects neurons against ischaemia-induced apoptosis.

PubMed

Wu, Xiaomei; Qian, Zhongming; Ke, Ya; Du, Fang; Zhu, Li

2009-01-01

Ischaemic preconditioning (IP) has been reported to protect the brain against subsequent lethal ischaemia, but it has not been used clinically to prevent ischaemic injury because of safety concerns. The aim of the present study was to see whether Ginkgolide B (GB) is capable of preconditioning as IP to protect neurons against ischaemic injury; if so, which mechanism is involved. Cultured mouse cortical neurons at day 8 were pre-treated with GB (120 micromol/l) for 24 hrs or exposed to short-term ischaemia (1 hr) followed by 24-hr normal culture to induce IP before being treated with severe ischaemia (5 hrs). GB and IP significantly increased cell viability, expression of hypoxia-inducible factor-1 alpha (HIF-1alpha), erythropoietin (EPO), phosphorylated Bad at serine 136 (136p-Bad) and phosphorylated glycogen synthase kinase- 3beta at serine 9 (p-GSK-3beta), and decreased the percentage of apoptotic cells and the level of active caspase-3 in severely ischaemic neurons. Moreover, LY294002 that is a specific inhibitor of phosphatidylinositol 3-kinase (PI3K) significantly reduced the enhanced expression of HIF-1alpha, EPO and 136p-Bad induced by GB and IP. These results suggest that GB, like IP in neurons, is capable of preconditioning against ischaemia-induced apoptosis, the mechanism of which may involve the PI3K signalling pathway.

Ginkgolide B preconditioning protects neurons against ischaemia-induced apoptosis

PubMed Central

Wu, Xiaomei; Qian, Zhongming; Ke, Ya; Du, Fang; Zhu, Li

2009-01-01

Ischaemic preconditioning (IP) has been reported to protect the brain against subsequent lethal ischaemia, but it has not been used clinically to prevent ischaemic injury because of safety concerns. The aim of the present study was to see whether Ginkgolide B (GB) is capable of preconditioning as IP to protect neurons against ischaemic injury; if so, which mechanism is involved. Cultured mouse cortical neurons at day 8 were pre-treated with GB (120 μmol/l) for 24 hrs or exposed to short-term ischaemia (1 hr) followed by 24-hr normal culture to induce IP before being treated with severe ischaemia (5 hrs). GB and IP significantly increased cell viability, expression of hypoxia-inducible factor-1 alpha (HIF-1α), erythropoietin (EPO), phosphorylated Bad at serine 136 (136p-Bad) and phosphorylated glycogen synthase kinase- 3β at serine 9 (p-GSK-3β), and decreased the percentage of apoptotic cells and the level of active caspase-3 in severely ischaemic neurons. Moreover, LY294002 that is a specific inhibitor of phosphatidylinositol 3-kinase (PI3K) significantly reduced the enhanced expression of HIF-1α, EPO and 136p-Bad induced by GB and IP. These results suggest that GB, like IP in neurons, is capable of preconditioning against ischaemia-induced apoptosis, the mechanism of which may involve the PI3K signalling pathway. PMID:19602048

α-Tocopherol Is Essential for Acquired Chill-Light Tolerance in the Cyanobacterium Synechocystis sp. Strain PCC 6803▿ †

PubMed Central

Yang, Yang; Yin, Chuntao; Li, Weizhi; Xu, Xudong

2008-01-01

Unlike Escherichia coli, the cyanobacterium Synechocystis sp. strain PCC 6803 is insensitive to chill (5°C) in the dark but rapidly losses viability when exposed to chill in the light (100 μmol photons m−2 s−1). Preconditioning at a low temperature (15°C) greatly enhances the chill-light tolerance of Synechocystis sp. strain PCC 6803. This phenomenon is called acquired chill-light tolerance (ACLT). Preconditioned wild-type cells maintained a substantially higher level of α-tocopherol after exposure to chill-light stress. Mutants unable to synthesize α-tocopherol, such as slr1736, slr1737, slr0089, and slr0090 mutants, almost completely lost ACLT. When exposed to chill without light, these mutants showed no or a slight difference from the wild type. When complemented, the slr0089 mutant regained its ACLT. Copper-regulated expression of slr0090 from PpetE controlled the level of α-tocopherol and ACLT. We conclude that α-tocopherol is essential for ACLT of Synechocystis sp. strain PCC 6803. The role of α-tocopherol in ACLT may be based largely on a nonantioxidant activity that is not possessed by other tocopherols or pathway intermediates. PMID:18165303

Ultraviolet B preconditioning enhances the hair growth-promoting effects of adipose-derived stem cells via generation of reactive oxygen species.

PubMed

Jeong, Yun-Mi; Sung, Young Kwan; Kim, Wang-Kyun; Kim, Ji Hye; Kwack, Mi Hee; Yoon, Insoo; Kim, Dae-Duk; Sung, Jong-Hyuk

2013-01-01

Hypoxia induces the survival and regenerative potential of adipose-derived stem cells (ASCs), but there are tremendous needs to find alternative methods for ASC preconditioning. Therefore, this work investigated: (1) the ability of low-dose ultraviolet B (UVB) radiation to stimulate the survival, migration, and tube-forming activity of ASCs in vitro; (2) the ability of UVB preconditioning to enhance the hair growth-promoting capacity of ASCs in vivo; and (3) the mechanism of action for ASC stimulation by UVB. Although high-dose UVB decreased the proliferation of ASCs, low-dose (10 or 20 mJ/cm(2)) treatment increased their survival, migration, and tube-forming activity. In addition, low-dose UVB upregulated the expression of ASC-derived growth factors, and a culture medium conditioned by UVB-irradiated ASCs increased the proliferation of dermal papilla and outer root sheet cells. Notably, injection of UVB-preconditioned ASCs into C(3)H/HeN mice significantly induced the telogen-to-anagen transition and increased new hair weight in vivo. UVB treatment significantly increased the generation of reactive oxygen species (ROS) in cultured ASCs, and inhibition of ROS generation by diphenyleneiodonium chloride (DPI) significantly attenuated UVB-induced ASC stimulation. Furthermore, NADPH oxidase 4 (Nox4) expression was induced in ASCs by UVB irradiation, and Nox4 silencing by small interfering RNA, like DPI, significantly reduced UVB-induced ROS generation. These results suggest that the primary involvement of ROS generation in UVB-mediated ASC stimulation occurs via the Nox4 enzyme. This is the first indication that a low dose of UVB radiation and/or the control of ROS generation could potentially be incorporated into a novel ASC preconditioning method for hair regeneration.

Voltage Preconditioning Allows Modulated Gene Expression in Neurons Using PEI-complexed siRNA

PubMed Central

Sridharan, Arati; Patel, Chetan; Muthuswamy, Jit

2013-01-01

We present here a high efficiency, high viability siRNA-delivery method using a voltage-controlled chemical transfection strategy to achieve modulated delivery of polyethylenimine (PEI) complexed with siRNA in an in vitro culture of neuro2A cells and neurons. Low voltage pulses were applied to adherent cells before the administration of PEI-siRNA complexes. Live assays of neuro2a cells transfected with fluorescently tagged siRNA showed an increase in transfection efficiency from 62 ± 14% to 98 ± 3.8% (after −1 V). In primary hippocampal neurons, transfection efficiencies were increased from 30 ± 18% to 76 ± 18% (after −1 V). Negligible or low-level transfection was observed after preconditioning at higher voltages, suggesting an inverse relationship with applied voltage. Experiments with propidium iodide ruled out the role of electroporation in the transfection of siRNAs suggesting an alternate electro-endocytotic mechanism. In addition, image analysis of preconditioned and transfected cells demonstrates siRNA uptake and loading that is tuned to preconditioning voltage levels. There is approximately a fourfold increase in siRNA loading after preconditioning at −1 V compared with the same at ±2–3 V. Modulated gene expression is demonstrated in a functional knockdown of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) in neuro2A cells using siRNA. Cell density and dendritic morphological changes are also demonstrated in modulated knockdown of brain derived neurotrophic factor (BDNF) in primary hippocampal neurons. The method reported here has potential applications in the development of high-throughput screening systems for large libraries of siRNA molecules involving difficult-to-transfect cells like neurons. PMID:23531602

Voltage Preconditioning Allows Modulated Gene Expression in Neurons Using PEI-complexed siRNA.

PubMed

Sridharan, Arati; Patel, Chetan; Muthuswamy, Jit

2013-03-26

We present here a high efficiency, high viability siRNA-delivery method using a voltage-controlled chemical transfection strategy to achieve modulated delivery of polyethylenimine (PEI) complexed with siRNA in an in vitro culture of neuro2A cells and neurons. Low voltage pulses were applied to adherent cells before the administration of PEI-siRNA complexes. Live assays of neuro2a cells transfected with fluorescently tagged siRNA showed an increase in transfection efficiency from 62 ± 14% to 98 ± 3.8% (after -1 V). In primary hippocampal neurons, transfection efficiencies were increased from 30 ± 18% to 76 ± 18% (after -1 V). Negligible or low-level transfection was observed after preconditioning at higher voltages, suggesting an inverse relationship with applied voltage. Experiments with propidium iodide ruled out the role of electroporation in the transfection of siRNAs suggesting an alternate electro-endocytotic mechanism. In addition, image analysis of preconditioned and transfected cells demonstrates siRNA uptake and loading that is tuned to preconditioning voltage levels. There is approximately a fourfold increase in siRNA loading after preconditioning at -1 V compared with the same at ±2-3 V. Modulated gene expression is demonstrated in a functional knockdown of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) in neuro2A cells using siRNA. Cell density and dendritic morphological changes are also demonstrated in modulated knockdown of brain derived neurotrophic factor (BDNF) in primary hippocampal neurons. The method reported here has potential applications in the development of high-throughput screening systems for large libraries of siRNA molecules involving difficult-to-transfect cells like neurons.Molecular Therapy-Nucleic Acids (2013) 2, e82; doi:10.1038/mtna.2013.10; published online 26 March 2013.

Histone Deacetylases Exert Class-Specific Roles in Conditioning the Brain and Heart Against Acute Ischemic Injury

PubMed Central

Aune, Sverre E.; Herr, Daniel J.; Kutz, Craig J.; Menick, Donald R.

2015-01-01

Ischemia-reperfusion (IR) injury comprises a significant portion of morbidity and mortality from heart and brain diseases worldwide. This enduring clinical problem has inspired myriad reports in the scientific literature of experimental interventions seeking to elucidate the pathology of IR injury. Elective cardiac surgery presents perhaps the most viable scenario for protecting the heart and brain from IR injury due to the opportunity to condition the organs prior to insult. The physiological parameters for the preconditioning of vital organs prior to insult through mechanical and pharmacological maneuvers have been heavily examined. These investigations have revealed new insights into how preconditioning alters cellular responses to IR injury. However, the promise of preconditioning remains unfulfilled at the clinical level, and research seeking to implicate cell signals essential to this protection continues. Recent discoveries in molecular biology have revealed that gene expression can be controlled through posttranslational modifications, without altering the chemical structure of the genetic code. In this scenario, gene expression is repressed by enzymes that cause chromatin compaction through catalytic removal of acetyl moieties from lysine residues on histones. These enzymes, called histone deacetylases (HDACs), can be inhibited pharmacologically, leading to the de-repression of protective genes. The discovery that HDACs can also alter the function of non-histone proteins through posttranslational deacetylation has expanded the potential impact of HDAC inhibitors for the treatment of human disease. HDAC inhibitors have been applied in a very small number of experimental models of IR. However, the scientific literature contains an increasing number of reports demonstrating that HDACs converge on preconditioning signals in the cell. This review will describe the influence of HDACs on major preconditioning signaling pathways in the heart and brain. PMID:26175715

Oxytocin signaling in basolateral and central amygdala nuclei differentially regulates the acquisition, expression, and extinction of context-conditioned fear in rats

PubMed Central

Campbell-Smith, Emma J.; Holmes, Nathan M.; Lingawi, Nura W.; Panayi, Marios C.

2015-01-01

The present study investigated how oxytocin (OT) signaling in the central (CeA) and basolateral (BLA) amygdala affects acquisition, expression, and extinction of context-conditioned fear (freezing) in rats. In the first set of experiments, acquisition of fear to a shocked context was impaired by a preconditioning infusion of synthetic OT into the CeA (Experiment 1) or BLA (Experiment 2). In the second set of experiments, expression of context fear was enhanced by a pre- or post-extinction CeA infusion of synthetic OT (Experiments 3–6) or a selective OT receptor agonist, TGOT (Experiment 4). This enhancement of fear was blocked by coadministration of an OT receptor antagonist, OTA (Experiment 5) and context fear was suppressed by administration of the antagonist alone (Experiment 6). In the third set of experiments, expression of context fear was suppressed, not enhanced, by a preextinction BLA infusion of synthetic OT or a selective OT receptor agonist, TGOT (Experiments 7 and 8). This suppression of fear was blocked by coadministration of the OT receptor antagonist, OTA (Experiment 8). Taken together, these findings show that the involvement of the CeA and BLA in expression and extinction of context-conditioned fear is dissociable, and imply a critical role for oxytocin signaling in amygdala-based regulation of aversive learning. PMID:25878137

Stress alters asenapine-induced Fos expression in the Meynert's nucleus: response of adjacent hypocretin and melanin-concentrating hormone neurons in rat.

PubMed

Majercikova, Z; Kiss, A

2016-01-01

Asenapine (ASE), an atypical antipsychotic drug used in the treatment of schizophrenia, induces Fos expression in forebrain. Effect of ASE on activity of basal nucleus of Meynert (NBM) cells, a part of the striatal-cortical circuits, was studied. We were also interested to reveal whether a chronic unpredictable variable mild stress (CMS) preconditioning might affect the ASE impact. Rats were divided into as follows: controls-vehicle, controls-ASE, stressed-vehicle and stressed-ASE groups. CMS included restrain, social isolation, crowding, swimming and cold applied for 21 days. On the 22nd day, rats were subcutaneously injected with ASE (0.3 mg/kg) or vehicle (saline 300 μl/rat), 90 min prior euthanizing. After transcardial fixation, brains were cut into 30 μm thick coronal sections. Fos protein presence, as indicator of cell activity, was detected by ABC immunohistochemistry. Hypocretin (Hcrt) and melanin-concentrating hormone (MCH) containing cells were visualized with fluorescent dyes. ASE induced significant increase in Fos expression in NBM in both controls and CMS preconditioned rats in comparison with the related vehicle-treated controls. CMS preconditioning, however, significantly lowered the Fos response to ASE in NBM. From Hrct and MCH cells, only Hcrt ones displayed Fos presence in response to ASE. This study demonstrates for the first time that ASE may target a special group of cells occupying NBM, which effect can be modulated by CMS preconditioning. This finding extends a view that ASE impact may extend beyond the classical forebrain target areas common for the action of all antipsychotics and might be helpful in the identification of sites and side effects of its therapeutic actions.

Proteomics-based network analysis characterizes biological processes and pathways activated by preconditioned mesenchymal stem cells in cardiac repair mechanisms.

PubMed

Di Silvestre, Dario; Brambilla, Francesca; Scardoni, Giovanni; Brunetti, Pietro; Motta, Sara; Matteucci, Marco; Laudanna, Carlo; Recchia, Fabio A; Lionetti, Vincenzo; Mauri, Pierluigi

2017-05-01

We have demonstrated that intramyocardial delivery of human mesenchymal stem cells preconditioned with a hyaluronan mixed ester of butyric and retinoic acid (MSCp + ) is more effective in preventing the decay of regional myocardial contractility in a swine model of myocardial infarction (MI). However, the understanding of the role of MSCp + in proteomic remodeling of cardiac infarcted tissue is not complete. We therefore sought to perform a comprehensive analysis of the proteome of infarct remote (RZ) and border zone (BZ) of pigs treated with MSCp + or unconditioned stem cells. Heart tissues were analyzed by MudPIT and differentially expressed proteins were selected by a label-free approach based on spectral counting. Protein profiles were evaluated by using PPI networks and their topological analysis. The proteomic remodeling was largely prevented in MSCp + group. Extracellular proteins involved in fibrosis were down-regulated, while energetic pathways were globally up-regulated. Cardioprotectant pathways involved in the production of keto acid metabolites were also activated. Additionally, we found that new hub proteins support the cardioprotective phenotype characterizing the left ventricular BZ treated with MSCp + . In fact, the up-regulation of angiogenic proteins NCL and RAC1 can be explained by the increase of capillary density induced by MSCp + . Our results show that angiogenic pathways appear to be uniquely positioned to integrate signaling with energetic pathways involving cardiac repair. Our findings prompt the use of proteomics-based network analysis to optimize new approaches preventing the post-ischemic proteomic remodeling that may underlie the limited self-repair ability of adult heart. Copyright © 2017 Elsevier B.V. All rights reserved.

Performance-enhanced mesenchymal stem cells via intracellular delivery of steroids

NASA Astrophysics Data System (ADS)

Ankrum, James A.; Dastidar, Riddhi G.; Ong, Joon Faii; Levy, Oren; Karp, Jeffrey M.

2014-04-01

Inadequate immunomodulatory potency of mesenchymal stem cells (MSC) may limit their therapeutic efficacy. We report glucocorticoid steroids augment MSC expression and activity of indoleamine-2,3-dioxygenase (IDO), a primary mediator of MSC immunomodulatory function. This effect depends on signaling through the glucocorticoid receptor and is mediated through up-regulation of FOXO3. Treatment of MSCs with glucocorticoids, budesonide or dexamethasone, enhanced IDO expression following IFN-γ stimulation in multiple donors and was able to restore IDO expression in over-passaged MSCs. As IDO enhancement was most notable when cells were continuously exposed to budesonide, we engineered MSC with budesonide loaded PLGA microparticles. MSC efficiently internalized budesonide microparticles and exhibited 4-fold enhanced IDO activity compared to budesonide preconditioned and naïve MSC, resulting in a 2-fold improvement in suppression of stimulated peripheral blood mononuclear cells in an IDO-dependent manner. Thus, the augmentation of MSC immune modulation may abrogate challenges associated with inadequate potency and enhance their therapeutic efficacy.

Performance-enhanced mesenchymal stem cells via intracellular delivery of steroids

PubMed Central

Ankrum, James A.; Dastidar, Riddhi G.; Ong, Joon Faii; Levy, Oren; Karp, Jeffrey M.

2014-01-01

Inadequate immunomodulatory potency of mesenchymal stem cells (MSC) may limit their therapeutic efficacy. We report glucocorticoid steroids augment MSC expression and activity of indoleamine-2,3-dioxygenase (IDO), a primary mediator of MSC immunomodulatory function. This effect depends on signaling through the glucocorticoid receptor and is mediated through up-regulation of FOXO3. Treatment of MSCs with glucocorticoids, budesonide or dexamethasone, enhanced IDO expression following IFN-γ stimulation in multiple donors and was able to restore IDO expression in over-passaged MSCs. As IDO enhancement was most notable when cells were continuously exposed to budesonide, we engineered MSC with budesonide loaded PLGA microparticles. MSC efficiently internalized budesonide microparticles and exhibited 4-fold enhanced IDO activity compared to budesonide preconditioned and naïve MSC, resulting in a 2-fold improvement in suppression of stimulated peripheral blood mononuclear cells in an IDO-dependent manner. Thus, the augmentation of MSC immune modulation may abrogate challenges associated with inadequate potency and enhance their therapeutic efficacy. PMID:24717973

Major role of the PI3K/Akt pathway in ischemic tolerance induced by sublethal oxygen-glucose deprivation in cortical neurons in vitro.

PubMed

Bhuiyan, Mohammad Iqbal Hossain; Jung, Seo Yun; Kim, Hyoung Ja; Lee, Yong Sup; Jin, Changbae

2011-06-01

Ischemic preconditioning can provide protection to neurons from subsequent lethal ischemia. The molecular mechanisms of neuronal ischemic tolerance, however, are still not well-known. The present study, therefore, examined the role of MAPK and PI3K/Akt pathways in ischemic tolerance induced by preconditioning with sublethal oxygen-glucose deprivation (OGD) in cultured rat cortical neurons. Ischemic tolerance was simulated by preconditioning of the neurons with sublethal 1-h OGD imposed 12 h before lethal 3-h OGD. The time-course studies of relative phosphorylation and expression levels of ERK1/2, JNK and p38 MAPK showed lack of their involvement in ischemic tolerance. However, there were significant increases in Akt phosphorylation levels during the reperfusion period following preconditioned lethal OGD. In addition, Bcl-2 associated death promoter (Bad) and GSK-3β were also found to be inactivated during that reperfusion period. Finally, treatment with an inhibitor of PI3K, wortmannin, applied from 15 min before and during lethal OGD abolished not only the preconditioning-induced neuroprotection but also the Akt activation. Concomitant with blockade of the Akt activation, PI3K inhibition also resulted in activation of Bad and GSK-3β. The results suggest that ischemic tolerance induced by sublethal OGD preconditioning is primarily mediated through activation of the PI3K/Akt pathway, but not the MAPK pathway, in rat cortical neurons.

Preconditioning in neuroprotection: From hypoxia to ischemia

PubMed Central

Li, Sijie; Hafeez, Adam; Noorulla, Fatima; Geng, Xiaokun; Shao, Guo; Ren, Changhong; Lu, Guowei; Zhao, Heng; Ding, Yuchuan; Ji, Xunming

2017-01-01

Sublethal hypoxic or ischemic events can improve the tolerance of tissues, organs, and even organisms from subsequent lethal injury caused by hypoxia or ischemia. This phenomenon has been termed hypoxic or ischemic preconditioning (HPC or IPC) and is well established in the heart and the brain. This review aims to discuss HPC and IPC with respect to their historical development and advancements in our understanding of the neurochemical basis for their neuroprotective role. Through decades of collaborative research and studies of HPC and IPC in other organ systems, our understanding of HPC and IPC-induced neuroprotection has expanded to include: early- (phosphorylation targets, transporter regulation, interfering RNA) and late- (regulation of genes like EPO, VEGF, and iNOS) phase changes, regulators of programmed cell death, members of metabolic pathways, receptor modulators, and many other novel targets. The rapid acceleration in our understanding of HPC and IPC will help facilitate transition into the clinical setting. PMID:28110083

Effects and interaction, of cariporide and preconditioning on cardiac arrhythmias and infarction in rat in vivo

PubMed Central

Aye, Nu Nu; Komori, Sadayoshi; Hashimoto, Keitaro

1999-01-01

Although Na+-H+ exchange (NHE) inhibitors are reported to protect the myocardium against ischaemic injury, NHE activation has also been proposed as a potential mechanism of ischaemic preconditioning-induced protection. This study was performed to test any modifiable effect of cariporide, an NHE inhibitor, on cardioprotective effects of preconditioning.Anaesthetized rats were subjected to 30 min of coronary artery occlusion and 150 min of reperfusion. The preconditioning (PC) was induced by 3 min of ischaemia and 10 min of reperfusion (1PC) or three episodes of 3 min ischaemia and 5 min reperfusion (3PC). Cariporide (0.3 mg kg−1) an NHE inhibitor, was administered 30 min (cari(30)) or 45 min (cari(45)) before coronary ligation (n=8–11 for each group).Ventricular arrhythmias during 30 min ischaemia and infarct size (measured by triphenyltetrazolium (TTC) and expressed as a per cent area at risk (%AAR)) were determined. Cari(30) reduced ventricular fibrillation (VF) incidence and infarct size (from 45 to 0% and 34±4 to 9±2%; each P<0.05), whereas cari(45) did not. Likewise, 3PC reduced these variables (to 0% and 10±2%; P<0.05 in each case) whereas 1PC did not. Moreover, subthreshold preconditioning (1PC) and cariporide (cari(45)), when combined, reduced VF incidence and infarct size (to 0% and 15+3%; each P<0.05).In conclusion, changes in NHE activity do not seem to be responsible for the cardioprotective action of ischaemic preconditioning. Protective effects of NHE inhibition and subthreshold preconditioning appear to act additively. PMID:10433514

Exogenous Gene Transmission of Isocitrate Dehydrogenase 2 Mimics Ischemic Preconditioning Protection.

PubMed

Kolb, Alexander L; Corridon, Peter R; Zhang, Shijun; Xu, Weimin; Witzmann, Frank A; Collett, Jason A; Rhodes, George J; Winfree, Seth; Bready, Devin; Pfeffenberger, Zechariah J; Pomerantz, Jeremy M; Hato, Takashi; Nagami, Glenn T; Molitoris, Bruce A; Basile, David P; Atkinson, Simon J; Bacallao, Robert L

2018-04-01

Ischemic preconditioning confers organ-wide protection against subsequent ischemic stress. A substantial body of evidence underscores the importance of mitochondria adaptation as a critical component of cell protection from ischemia. To identify changes in mitochondria protein expression in response to ischemic preconditioning, we isolated mitochondria from ischemic preconditioned kidneys and sham-treated kidneys as a basis for comparison. The proteomic screen identified highly upregulated proteins, including NADP+-dependent isocitrate dehydrogenase 2 (IDH2), and we confirmed the ability of this protein to confer cellular protection from injury in murine S3 proximal tubule cells subjected to hypoxia. To further evaluate the role of IDH2 in cell protection, we performed detailed analysis of the effects of Idh2 gene delivery on kidney susceptibility to ischemia-reperfusion injury. Gene delivery of IDH2 before injury attenuated the injury-induced rise in serum creatinine ( P <0.05) observed in controls and increased the mitochondria membrane potential ( P <0.05), maximal respiratory capacity ( P <0.05), and intracellular ATP levels ( P <0.05) above those in controls. This communication shows that gene delivery of Idh2 can confer organ-wide protection against subsequent ischemia-reperfusion injury and mimics ischemic preconditioning. Copyright © 2018 by the American Society of Nephrology.

"Preconditioning" with latrepirdine, an adenosine 5'-monophosphate-activated protein kinase activator, delays amyotrophic lateral sclerosis progression in SOD1(G93A) mice.

PubMed

Coughlan, Karen S; Mitchem, Mollie R; Hogg, Marion C; Prehn, Jochen H M

2015-02-01

Adenosine 5'-monophosphate-activated protein kinase (AMPK) is a master regulator of energy balance. As energy imbalance is documented as a key pathologic feature of amyotrophic lateral sclerosis (ALS), we investigated AMPK as a pharmacologic target in SOD1(G93A) mice. We noted a strong activation of AMPK in lumbar spinal cords of SOD1(G93A) mice. Pharmacologic activation of AMPK has shown protective effects in neuronal "preconditioning" models. We tested the hypothesis that "preconditioning" with a small molecule activator of AMPK, latrepirdine, exerts beneficial effects on disease progression. SOD1(G93A) mice (n = 24 animals per group; sex and litter matched) were treated with latrepirdine (1 μg/kg, intraperitoneal) or vehicle from postnatal day 70 to 120. Treatment with latrepirdine increased AMPK activity in primary mouse motor neuron cultures and in SOD1(G93A) lumbar spinal cords. Mice "preconditioned" with latrepirdine showed a delayed symptom onset and a significant increase in life span (p < 0.01). Our study suggests that "preconditioning" with latrepirdine may represent a possible therapeutic strategy for individuals harboring ALS-associated gene mutations who are at risk for developing ALS. Copyright © 2015 Elsevier Inc. All rights reserved.

Hyperbaric oxygen preconditioning protects against traumatic brain injury at high altitude.

PubMed

Hu, S L; Hu, R; Li, F; Liu, Z; Xia, Y Z; Cui, G Y; Feng, H

2008-01-01

Recent studies have shown that preconditioning with hyperbaric oxygen (HBO) can reduce ischemic and hemorrhagic brain injury. We investigated effects of HBO preconditioning on traumatic brain injury (TBI) at high altitude and examined the role of matrix metalloproteinase-9 (MMP-9) in such protection. Rats were randomly divided into 3 groups: HBO preconditioning group (HBOP; n = 13), high-altitude group (HA; n = 13), and high-altitude sham operation group (HASO; n = 13). All groups were subjected to head trauma by weight-drop device, except for HASO group. HBOP rats received 5 sessions of HBO preconditioning (2.5 ATA, 100% oxygen, 1 h daily) and then were kept in hypobaric chamber at 0.6 ATA (to simulate pressure at 4000m altitude) for 3 days before operation. HA rats received control pretreatment (1 ATA, room air, 1 h daily), then followed the same procedures as HBOP group. HASO rats were subjected to skull opening only without brain injury. Twenty-four hours after TBI, 7 rats from each group were examined for neurological function and brain water content; 6 rats from each group were killed for analysis by H&E staining and immunohistochemistry. Neurological outcome in HBOP group (0.71 +/- 0.49) was better than HA group (1.57 +/- 0.53; p < 0.05). Preconditioning with HBO significantly reduced percentage of brain water content (86.24 +/- 0.52 vs. 84.60 +/- 0.37; p < 0.01). Brain morphology and structure seen by light microscopy was diminished in HA group, while fewer pathological injuries occurred in HBOP group. Compared to HA group, pretreatment with HBO significantly reduced the number of MMP-9-positive cells (92.25 +/- 8.85 vs. 74.42 +/- 6.27; p < 0.01). HBO preconditioning attenuates TBI in rats at high altitude. Decline in MMP-9 expression may contribute to HBO preconditioning-induced protection of brain tissue against TBI.

The Neuronal Ischemic Tolerance Is Conditioned by the Tp53 Arg72Pro Polymorphism.

PubMed

Ramos-Araque, Maria E; Rodriguez, Cristina; Vecino, Rebeca; Cortijo Garcia, Elisa; de Lera Alfonso, Mercedes; Sanchez Barba, Mercedes; Colàs-Campàs, Laura; Purroy, Francisco; Arenillas, Juan F; Almeida, Angeles; Delgado-Esteban, Maria

2018-04-23

Cerebral preconditioning (PC) confers endogenous brain protection after stroke. Ischemic stroke patients with a prior transient ischemic attack (TIA) may potentially be in a preconditioned state. Although PC has been associated with the activation of pro-survival signals, the mechanism by which preconditioning confers neuroprotection is not yet fully clarified. Recently, we have described that PC-mediated neuroprotection against ischemic insult is promoted by p53 destabilization, which is mediated by its main regulator MDM2. Moreover, we have previously described that the human Tp53 Arg72Pro single nucleotide polymorphism (SNP) controls susceptibility to ischemia-induced neuronal apoptosis and governs the functional outcome of patients after stroke. Here, we studied the contribution of the human Tp53 Arg72Pro SNP on PC-induced neuroprotection after ischemia. Our results showed that cortical neurons expressing the Pro72-p53 variant exhibited higher PC-mediated neuroprotection as compared with Arg72-p53 neurons. PC prevented ischemia-induced nuclear and cytosolic p53 stabilization in Pro72-p53 neurons. However, PC failed to prevent mitochondrial p53 stabilization, which occurs in Arg72-p53 neurons after ischemia. Furthermore, PC promoted neuroprotection against ischemia by controlling the p53/active caspase-3 pathway in Pro72-p53, but not in Arg72-p53 neurons. Finally, we found that good prognosis associated to TIA within 1 month prior to ischemic stroke was restricted to patients harboring the Pro72 allele. Our findings demonstrate that the Tp53 Arg72Pro SNP controls PC-promoted neuroprotection against a subsequent ischemic insult by modulating mitochondrial p53 stabilization and then modulates TIA-induced ischemic tolerance.

Repetitive acute intermittent hypoxia increases expression of proteins associated with plasticity in the phrenic motor nucleus

PubMed Central

Satriotomo, Irawan; Dale, Erica A.; Dahlberg, Jenny M.; Mitchell, Gordon S.

2015-01-01

Acute intermittent hypoxia (AIH) initiates plasticity in respiratory motor control, including phrenic long term facilitation (pLTF). Since pLTF is enhanced by preconditioning with repetitive exposure to AIH (rAIH), we hypothesized that a rAIH protocol consisting of 3 AIH exposures per week for 10 weeks (3×wAIH; AIH: 10, 5-min episodes of 10.5% O2; 5-min normoxic intervals) would enhance expression of molecules that play key roles in pLTF within the phrenic motor nucleus. Immunohistochemical analyses revealed that 3×wAIH for 10 weeks increased serotonin terminal density in the C4 phrenic motor nucleus and serotonin 2A (5-HT2A) receptor expression in presumptive phrenic motor neurons. Immunoreactive brain derived neurotrophic factor (BDNF) and its high affinity receptor (TrkB) also increased following 3×wAIH. 3×wAIH also increased expression of another hypoxia-sensitive growth factor known to elicit phrenic motor facilitation, vascular endothelial growth factor (VEGF), and its receptor (VEGFR-2). Kinases “downstream” from TrkB and VEGFR-2 were up-regulated in or near presumptive phrenic motor neurons, including phosphorylated extracellular-signal regulated kinase (p-ERK) and protein kinase B (p-AKT). Thus, 3×wAIH up-regulates neurochemicals known to be associated with phrenic motor plasticity. Since 3×wAIH upregulates pro-plasticity molecules without evidence for CNS pathology, it may be a useful therapeutic tool in treating disorders that cause respiratory insufficiency, such as spinal injury or motor neuron disease. PMID:22704858

Reduced expression of mitochondrial electron transport chain proteins from hibernating hearts relative to ischemic preconditioned hearts in the second window of protection.

PubMed

Cabrera, Jesús A; Butterick, Tammy A; Long, Eric K; Ziemba, Elizabeth A; Anderson, Lorraine B; Duffy, Cayla M; Sluiter, Willem; Duncker, Dirk J; Zhang, Jianyi; Chen, Yingjie; Ward, Herbert B; Kelly, Rosemary F; McFalls, Edward O

2013-07-01

Although protection against necrosis has been observed in both hibernating (HIB) and ischemic preconditioned hearts in the second window of protection (SWOP), a comparison of the mitochondrial proteome between the two entities has not been previously performed. Anesthetized swine underwent instrumentation with a fixed constrictor around the LAD artery and were followed for 12 weeks (HIB; N=7). A second group of anesthetized swine underwent ischemic preconditioning by inflating a balloon within the LAD artery 10 times for 2 min, each separated by 2 min reperfusion and were sacrificed 24h later (SWOP; N=7). Myocardial blood flow and high-energy nucleotides were obtained in the LAD region and normalized to remote regions. Post-sacrifice, protein content as measured with iTRAQ was compared in isolated mitochondria from the LAD area of a Sham heart. Basal regional blood flow in the LAD region when normalized to the remote region was 0.86±0.04 in HIB and 1.02±0.02 in SWOP tissue (P<0.05). Despite reduced regional blood flows in HIB hearts, ATP content in the LAD region, when normalized to the remote region was similar in HIB versus SWOP (1.06±0.06 and 1.02±0.05 respectively; NS) as was the transmural phosphocreatine (PCr) to ATP ratio (2.1±0.2 and 2.2±0.2 respectively; NS). Using iTRAQ, 64 common proteins were identified in HIB and SWOP hearts. Compared with SWOP, the relative abundance of mitochondrial proteins involved with electron transport chain (ETC) were reduced in HIB including NADH dehydrogenase, Cytochrome c reductase and oxidase, ATP synthase, and nicotinamide nucleotide transhydrogenase. Within chronically HIB heart tissue with reduced blood flow, the relative abundance of mitochondrial ETC proteins is decreased when compared with SWOP tissue. These data support the concept that HIB heart tissue subjected to chronically reduced blood flow is associated with a down-regulation in the expression of key mitochondrial proteins involved in electron transport. Published by Elsevier Ltd.

miR-218 is involved in the negative regulation of osteoclastogenesis and bone resorption by partial suppression of p38MAPK-c-Fos-NFATc1 signaling: Potential role for osteopenic diseases.

PubMed

Qu, Bo; Xia, Xun; Yan, Ming; Gong, Kai; Deng, Shaolin; Huang, Gang; Ma, Zehui; Pan, Xianming

2015-10-15

The increased osteoclastic activity accounts for pathological bone loss in diseases including osteoporosis. MicroRNAs are widely accepted to be involved in the regulation of osteopenic diseases. Recently, the low expression of miR-218 was demonstrated in CD14(+) peripheral blood mononuclear cells (PBMCs) from patients with postmenopausal osteoporosis. However, its role and the underlying mechanism in osteoporosis are still undefined. Here, an obvious decrease in miR-218 expression was observed during osteoclastogenesis under receptor activator of nuclear factor κB ligand (RANKL) stimulation, in both osteoclast precursors of bone marrow macrophages (BMMs) and RAW 264.7. Further analysis confirmed that overexpression of miR-218 obviously attenuated the formation of multinuclear mature osteoclasts, concomitant with the decrease in Trap and Cathepsin K levels, both the master regulators of osteoclastogenesis. Moreover, miR-218 up-regulation dramatically inhibited osteoclast precursor migration, actin ring formation and bone resorption. Mechanism assay demonstrated that miR-218 overexpression attenuated the expression of p38MAPK, c-Fos and NFATc1 signaling molecules. Following preconditioning with P79350, an agonist of p38MAPK, the inhibitor effect of miR-218 on osteoclastogenesis and bone-resorbing activity was strikingly ameliorated. Together, this study revealed a crucial role of miR-218 as a negative regulator for osteoclastogenesis and bone resorption by suppressing the p38MAPK-c-Fos-NFATc1 pathway. Accordingly, this research will provide a promising therapeutic agent against osteopenic diseases including osteoporosis. Copyright © 2015 Elsevier Inc. All rights reserved.

[Effects of BNP preconditioning on myocardial cell apoptosis and expressions of bcl-2 and Bax during myocardial ischemia-reperfusion injury in rats].

PubMed

Deng, Yu-Jun; Tan, Ning; Zeng, Hong-Ke; Fu, Yong-Heng; Dong, Xiao-Li

2010-12-28

To study the effects of B-type natriuretic peptide (BNP) preconditioning on the apoptosis and expressions of Bcl-2 and Bax in rat cardiomyocytes during myocardial ischemia-reperfusion. Twenty-one male Sprague-Dawley rats weighing (250 ± 50) g were randomly divided into 3 groups of sham operation (SHAM), ischemia-reperfusion (I/R) and B-type natriuretic peptide (BNP). A rat model of in vivo myocardial ischemia-reperfusion injury was established by ligating the left anterior descending coronary artery for 35 minutes and then reperfusing for 240 minutes. The apoptosis of myocardial cell was determined by terminal deoxynucleotidyl transferase mediated dUTP-biotin nick end-labeling (TUNEL) method. Real-time polymerase chain reaction and Western blot were used to detect the expression changes of Bcl-2 and Bax in rat ischemia myocardium. The apoptotic indices of SHAM, BNP and I/R groups were 5.4% ± 4.2%, 22.5% ± 9.5% and 45.2% ± 13.0% respectively (P < 0.05). The Bcl-2 protein expression of SHAM, BNP and I/R groups were 0.87 ± 0.09, 0.70 ± 0.07 and 0.38 ± 0.09 respectively (P < 0.05). The Bax protein expression of SHAM, BNP and I/R groups were 0.08 ± 0.04, 0.39 ± 0.09 and 0.71 ± 0.18 respectively (P < 0.01). The Bcl-2/Bax mRNA ratio of SHAN, BNP and I/R groups were 0.763 ± 0.154, 0.099 ± 0.025 and 0.022 ± 0.024 respectively (P < 0.05). The BNP preconditioning can decrease the myocardial apoptosis induced by ischemia-reperfusion injury. The mechanisms may be associated with an elevated expression of Bcl-2, an increased ratio of Bcl-2/Bax and a lowered expression of Bax.

Ischemic preconditioning enhances integrity of coronary endothelial tight junctions

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

Li, Zhao; Jin, Zhu-Qiu, E-mail: zhu-qiu.jin@sdstate.edu

2012-08-31

Highlights: Black-Right-Pointing-Pointer Cardiac tight junctions are present between coronary endothelial cells. Black-Right-Pointing-Pointer Ischemic preconditioning preserves the structural and functional integrity of tight junctions. Black-Right-Pointing-Pointer Myocardial edema is prevented in hearts subjected to ischemic preconditioning. Black-Right-Pointing-Pointer Ischemic preconditioning enhances translocation of ZO-2 from cytosol to cytoskeleton. -- Abstract: Ischemic preconditioning (IPC) is one of the most effective procedures known to protect hearts against ischemia/reperfusion (IR) injury. Tight junction (TJ) barriers occur between coronary endothelial cells. TJs provide barrier function to maintain the homeostasis of the inner environment of tissues. However, the effect of IPC on the structure and function of cardiacmore » TJs remains unknown. We tested the hypothesis that myocardial IR injury ruptures the structure of TJs and impairs endothelial permeability whereas IPC preserves the structural and functional integrity of TJs in the blood-heart barrier. Langendorff hearts from C57BL/6J mice were prepared and perfused with Krebs-Henseleit buffer. Cardiac function, creatine kinase release, and myocardial edema were measured. Cardiac TJ function was evaluated by measuring Evans blue-conjugated albumin (EBA) content in the extravascular compartment of hearts. Expression and translocation of zonula occludens (ZO)-2 in IR and IPC hearts were detected with Western blot. A subset of hearts was processed for the observation of ultra-structure of cardiac TJs with transmission electron microscopy. There were clear TJs between coronary endothelial cells of mouse hearts. IR caused the collapse of TJs whereas IPC sustained the structure of TJs. IR increased extravascular EBA content in the heart and myocardial edema but decreased the expression of ZO-2 in the cytoskeleton. IPC maintained the structure of TJs. Cardiac EBA content and edema were reduced in IPC hearts. IPC enhanced the translocation of ZO-2 from cytosol to cytoskeleton. In conclusion, TJs occur in normal mouse heart. IPC preserves the integrity of TJ structure and function that are vulnerable to IR injury.« less

Fetal asphyctic preconditioning modulates the acute cytokine response thereby protecting against perinatal asphyxia in neonatal rats.

PubMed

Vlassaks, Evi; Strackx, Eveline; Vles, Johan Sh; Nikiforou, Maria; Martinez-Martinez, Pilar; Kramer, Boris W; Gavilanes, Antonio Wd

2013-01-26

Perinatal asphyxia (PA) is a major cause of brain damage and neurodevelopmental impairment in infants. Recent investigations have shown that experimental sublethal fetal asphyxia (FA preconditioning) protects against a subsequent more severe asphyctic insult at birth. The molecular mechanisms of this protection have, however, not been elucidated. Evidence implicates that inflammatory cytokines play a protective role in the induction of ischemic tolerance in the adult brain. Accordingly, we hypothesize that FA preconditioning leads to changes in the fetal cytokine response, thereby protecting the newborn against a subsequent asphyctic insult. In rats, FA preconditioning was induced at embryonic day 17 by clamping the uterine vasculature for 30 min. At term birth, global PA was induced by placing the uterine horns, containing the pups, in a saline bath for 19 min. We assessed, at different time points after FA and PA, mRNA and protein expression of several cytokines and related receptor mRNA levels in total hemispheres of fetal and neonatal brains. Additionally, we measured pSTAT3/STAT3 levels to investigate cellular responses to these cytokines. Prenatally, FA induced acute downregulation in IL-1β, TNF-α and IL-10 mRNA levels. At 96 h post FA, IL-6 mRNA and IL-10 protein expression were increased in FA brains compared with controls. Two hours after birth, all proinflammatory cytokines and pSTAT3/STAT3 levels decreased in pups that experienced FA and/or PA. Interestingly, IL-10 and IL-6 mRNA levels increased after PA. When pups were FA preconditioned, however, IL-10 and IL-6 mRNA levels were comparable to those in controls. FA leads to prenatal changes in the neuroinflammatory response. This modulation of the cytokine response probably results in the protective inflammatory phenotype seen when combining FA and PA and may have significant implications for preventing post-asphyctic perinatal encephalopathy.

Fetal asphyctic preconditioning modulates the acute cytokine response thereby protecting against perinatal asphyxia in neonatal rats

PubMed Central

2013-01-01

Background Perinatal asphyxia (PA) is a major cause of brain damage and neurodevelopmental impairment in infants. Recent investigations have shown that experimental sublethal fetal asphyxia (FA preconditioning) protects against a subsequent more severe asphyctic insult at birth. The molecular mechanisms of this protection have, however, not been elucidated. Evidence implicates that inflammatory cytokines play a protective role in the induction of ischemic tolerance in the adult brain. Accordingly, we hypothesize that FA preconditioning leads to changes in the fetal cytokine response, thereby protecting the newborn against a subsequent asphyctic insult. Methods In rats, FA preconditioning was induced at embryonic day 17 by clamping the uterine vasculature for 30 min. At term birth, global PA was induced by placing the uterine horns, containing the pups, in a saline bath for 19 min. We assessed, at different time points after FA and PA, mRNA and protein expression of several cytokines and related receptor mRNA levels in total hemispheres of fetal and neonatal brains. Additionally, we measured pSTAT3/STAT3 levels to investigate cellular responses to these cytokines. Results Prenatally, FA induced acute downregulation in IL-1β, TNF-α and IL-10 mRNA levels. At 96 h post FA, IL-6 mRNA and IL-10 protein expression were increased in FA brains compared with controls. Two hours after birth, all proinflammatory cytokines and pSTAT3/STAT3 levels decreased in pups that experienced FA and/or PA. Interestingly, IL-10 and IL-6 mRNA levels increased after PA. When pups were FA preconditioned, however, IL-10 and IL-6 mRNA levels were comparable to those in controls. Conclusions FA leads to prenatal changes in the neuroinflammatory response. This modulation of the cytokine response probably results in the protective inflammatory phenotype seen when combining FA and PA and may have significant implications for preventing post-asphyctic perinatal encephalopathy. PMID:23351591

N-Acetyl cysteine protects diabetic mouse derived mesenchymal stem cells from hydrogen-peroxide-induced injury: A novel hypothesis for autologous stem cell transplantation.

PubMed

Ali, Fatima; Khan, Mohsin; Khan, Shaheen N; Riazuddin, Sheikh

2016-03-01

Stem cell transplantation is one of the therapeutic options available to repair damaged organs. However, transplanted cells entail several challenges including their survival in diabetes-affected injured tissue. This study was designed to determine the effects of preconditioning of mesenchymal stem cells (MSCs) with N-acetyl cysteine (NAC), a widely used antioxidant drug. Diabetic-mouse-derived MSCs (blood glucose ≥ 300 mg/dL) were preconditioned with 30 mM NAC for 1 hour followed by oxidative injury with 100 μM hydrogen peroxide (H2O2) for 1 hour. Gene expression analysis showed marked upregulation of prosurvival genes (Akt and Bcl-2) and significantly downregulated expression of proapoptotic and stress genes (Capase-3, Bax, Bak, p53, p38, and NF-κB) in the 30 mM-NAC-treated group when compared with those cells treated with H2O2 alone. NAC preconditioning improved cell viability, decreased lactate dehydrogenase release, β-galactosidase activity, and Annexin-V-positive cells. Also, amelioration of oxidative stress, as shown by a decrease in malondialdehyde level and an increase in superoxide dismutase and catalase activities and glutathione level, was observed in the 30 mM-NAC-treated group in comparison to cells treated with H2O2 alone. This study demonstrates the potential benefits of pharmacological preconditioning of diabetic-mouse-derived MSCs with NAC for amelioration of apoptosis and oxidative stress in H2O2 induced injury. Copyright © 2016. Published by Elsevier Taiwan LLC.

Proper Heat Shock Pretreatment Reduces Acute Liver Injury Induced by Carbon Tetrachloride and Accelerates Liver Repair in Mice

PubMed Central

Li, San-Qiang; Wang, Dong-Mei; Shu, You-Ju; Wan, Xue-Dong; Xu, Zheng-Shun; Li, En-Zhong

2013-01-01

Whether proper heat shock preconditioning can reduce liver injury and accelerate liver repair after acute liver injury is worth study. So mice received heat shock preconditioning at 40°C for 10 minutes (min), 20 min or 30 min and recovered at room temperature for 8 hours (h) under normal feeding conditions. Then acute liver injury was induced in the heat shock-pretreated mice and unheated control mice by intraperitoneal (i.p.) injection of carbon tetrachloride (CCl4). Hematoxylin and eosin (H&E) staining, serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels and the expression levels of heat shock protein 70 (HSP70), cytochrome P450 1A2 (CYP1A2) and proliferating cell nuclear antigen (PCNA) were detected in the unheated control mice and heat shock-pretreated mice after CCl4 administration. Our results showed that heat shock preconditioning at 40°C for 20 min remarkably improved the mice’s survival rate (P<0.05), lowered the levels of serum AST and ALT (P<0.05), induced HSP70 (P<0.01), CYP1A2 (P<0.01) and PCNA (P<0.05) expression, effectively reduced liver injury (P<0.05) and accelerated the liver repair (P<0.05) compared with heat shock preconditioning at 40°C for 10 min or 30 min in the mice after acute liver injury induced by CCl4 when compared with the control mice. Our results may be helpful in further investigation of heat shock pretreatment as a potential clinical approach to target liver injury PMID:24526809

Parallel pathways for cross-modal memory retrieval in Drosophila.

PubMed

Zhang, Xiaonan; Ren, Qingzhong; Guo, Aike

2013-05-15

Memory-retrieval processing of cross-modal sensory preconditioning is vital for understanding the plasticity underlying the interactions between modalities. As part of the sensory preconditioning paradigm, it has been hypothesized that the conditioned response to an unreinforced cue depends on the memory of the reinforced cue via a sensory link between the two cues. To test this hypothesis, we studied cross-modal memory-retrieval processing in a genetically tractable model organism, Drosophila melanogaster. By expressing the dominant temperature-sensitive shibire(ts1) (shi(ts1)) transgene, which blocks synaptic vesicle recycling of specific neural subsets with the Gal4/UAS system at the restrictive temperature, we specifically blocked visual and olfactory memory retrieval, either alone or in combination; memory acquisition remained intact for these modalities. Blocking the memory retrieval of the reinforced olfactory cues did not impair the conditioned response to the unreinforced visual cues or vice versa, in contrast to the canonical memory-retrieval processing of sensory preconditioning. In addition, these conditioned responses can be abolished by blocking the memory retrieval of the two modalities simultaneously. In sum, our results indicated that a conditioned response to an unreinforced cue in cross-modal sensory preconditioning can be recalled through parallel pathways.

Preconditioning potential of purmorphamine: a hedgehog activator against ischaemic reperfusion injury in ovariectomised rat heart.

PubMed

Sharma, Shweta; Kaur, Avileen; Sharma, Saurabh

2018-04-01

The present study was been designed to investigate the role and pharmacological potential of hedgehog in oestrogen-deficient rat heart. Oestrogen deficiency was produced in female Wistar rats by the surgical removal of both ovaries and these animals were used four weeks later. Isolated rat heart was subjected to 30 min ischaemia followed by 120 min of reperfusion (I/R). The heart was subjected to pharmacological preconditioning with the hedgehog agonist purmorphamine (1μM) and GDC-0449, a hedgehog antagonist, in the last episode of reperfusion before I/R. Myocardial infarction was assessed in terms of the increase in lactate dehydrogenase (LDH), creatinine kinase-MB (CK-MB), myeloperoxidase (MPO) level and infarct size (triphenyltetrazolium chloride staining). Immunohistochemistry analysis was done for the assessment of tumour necrosis factor (TNF)-α level in cardiac tissue. eNOS expression was estimated by rt-PCR. Pharmacological preconditioning with purmorphamine significantly attenuated I/R-induced myocardial infarction, TNF-α, MPO level and release of LDH and CK-MB compared to the I/R control group. However, GDC-0449 prevented the ameliorative preconditioning effect of estradiol. It may be concluded that the hedgehog agonist purmorphamine prevents the ovariectomised heart from ischaemic reperfusion injury.

Hydrogen Sulfide Preconditioning Protects Rat Liver against Ischemia/Reperfusion Injury by Activating Akt-GSK-3β Signaling and Inhibiting Mitochondrial Permeability Transition

PubMed Central

Zhang, Hao; Xu, Fengying; Zou, Zui; Liu, Meng; Wang, Quanxing; Miao, Mingyong; Shi, Xueyin

2013-01-01

Hydrogen sulfide (H2S) is the third most common endogenously produced gaseous signaling molecule, but its impact on hepatic ischemia/reperfusion (I/R) injury, especially on mitochondrial function, remains unclear. In this study, rats were randomized into Sham, I/R, ischemia preconditioning (IPC) or sodium hydrosulfide (NaHS, an H2S donor) preconditioning groups. To establish a model of segmental (70%) warm hepatic ischemia, the hepatic artery, left portal vein and median liver lobes were occluded for 60 min and then unclamped to allow reperfusion. Preconditioning with 12.5, 25 or 50 μmol/kg NaHS prior to the I/R insult significantly increased serum H2S levels, and, similar to IPC, NaHS preconditioning decreased alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels in the plasma and prevented hepatocytes from undergoing I/R-induced necrosis. Moreover, a sub-toxic dose of NaHS (25 μmol/kg) did not disrupt the systemic hemodynamics but dramatically inhibited mitochondrial permeability transition pore (MPTP) opening and thus prevented mitochondrial-related cell death and apoptosis. Mechanistic studies revealed that NaHS preconditioning markedly increased the expression of phosphorylated protein kinase B (p-Akt), phosphorylated glycogen synthase kinase-3 beta (p-GSK-3β) and B-cell lymphoma-2 (Bcl-2) and decreased the release of mitochondrial cytochrome c and cleaved caspase-3/9 levels. Therefore, NaHS administration prior to hepatic I/R ameliorates mitochondrial and hepatocellular damage through the inhibition of MPTP opening and the activation of Akt-GSK-3β signaling. Furthermore, this study provides experimental evidence for the clinical use of H2S to reduce liver damage after perioperative I/R injury. PMID:24058562

The role of adenosine in preconditioning by brief pressure overload in rats.

PubMed

Huang, Cheng-Hsiung; Tsai, Shen-Kou; Chiang, Shu-Chiung; Lai, Chang-Chi; Weng, Zen-Chung

2015-08-01

Brief pressure overload of the left ventricle reduced myocardial infarct (MI) size in rabbits has been previously reported. Its effects in other species are not known. This study investigates effects of pressure overload and the role of adenosine in rats in this study. MI was induced by 40-minute occlusion of the left anterior descending coronary artery followed by 3-hour reperfusion. MI size was determined by triphenyl tetrazolium chloride staining. Brief pressure overload was induced by two 10-minute episodes of partial snaring of the ascending aorta. Systolic left ventricular pressure was raised 50% above the baseline value. Ischemic preconditioning was elicited by two 10-minute coronary artery occlusions. The MI size (mean ± standard deviation), expressed as percentage of area at risk, was significantly reduced in the pressure overload group as well as in the ischemic preconditioning group (17.4 ± 3.0% and 18.2 ± 1.5% vs. 26.6 ± 2.4% in the control group, p < 0.001). Pretreatment with 8-(p-sulfophenyl)-theophylline (SPT), an inhibitor of adenosine receptors, did not significantly limit the protection by pressure overload and ischemic preconditioning (18.3 ± 1.5% and 18.2 ± 2.0%, respectively, p < 0.001). SPT itself did not affect the extent of infarct (25.4 ± 2.0%). The hemodynamics, area at risk and mortality were not significantly different among all groups of animals. Brief pressure overload of the left ventricle preconditioned rat myocardium against infarction. Because SPT did not significantly alter MI size reduction, our results did not support a role of adenosine in preconditioning by pressure overload in rats. Copyright © 2013. Published by Elsevier B.V.

[Octanol preconditioning alleviates mouse cardiomyocyte swelling induced by simulated ischemia/reperfusion challenge in vitro].

PubMed

Luo, Yukun; Fang, Jun; Fan, Lin; Lin, Chaogui; Chen, Zhaoyang; Chen, Lianglong

2012-10-01

To investigate the role of connexin 43-formed hemichannels in cell volume regulation induced by simulated ischemia/reperfusion (SI/R). Mouse cardiomyocytes isolated on a Langendorff apparatus with enzyme solution were aliquoted into control, SI/R and SI/R +octanol groups. Calcein-AM was used to stain the cells and the cell volume was measured with confocal microscope by stack scanning. Trypan blue was used to measure the cell viability after the treatments. Calcein-AM staining and cofocal microscopy yielded stable and reproducible results for cell volume measurement. Mouse cardiomyocytes subjected to simulated SI/R showed obvious cell swelling as compared with the control cells [(126∓6)% vs 100%, P<0.05], and octanol preconditioning significantly attenuated the cell swelling [(113∓6)%, P<0.05]. SI/R caused a significant reduction of the cell viability compared to the control cells [(19∓2)% vs (45∓3)%, P<0.01], and octanol preconditioning obviously reduced the viability of the cells with SI/R challenge [(31∓2)%, P<0.01]. Connexin 43-formed hemichannels are involved in the regulation of cardiomyocyte volumes induced by SI/R challenge, and octanol can alleviate the cell swelling to enhance the viability of the cardiomyocytes following SI/R.

The differential effects of 2% oxygen preconditioning on the subsequent differentiation of mouse and human pluripotent stem cells.

PubMed

Fynes, Kate; Tostoes, Rui; Ruban, Ludmila; Weil, Ben; Mason, Christopher; Veraitch, Farlan S

2014-08-15

A major challenge facing the development of effective cell therapies is the efficient differentiation of pluripotent stem cells (PSCs) into pure populations. Lowering oxygen tension to physiological levels can affect both the expansion and differentiation stages. However, to date, there are no studies investigating the knock-on effect of culturing PSCs under low oxygen conditions on subsequent lineage commitment at ambient oxygen levels. PSCs were passaged three times at 2% O2 before allowing cells to spontaneously differentiate as embryoid bodies (EBs) in high oxygen (20% O2) conditions. Maintenance of mouse PSCs in low oxygen was associated with a significant increase in the expression of early differentiation markers FGF5 and Eomes, while conversely we observed decreased expression of these genes in human PSCs. Low oxygen preconditioning primed mouse PSCs for their subsequent differentiation into mesodermal and endodermal lineages, as confirmed by increased gene expression of Eomes, Goosecoid, Brachyury, AFP, Sox17, FoxA2, and protein expression of Brachyury, Eomes, Sox17, FoxA2, relative to high oxygen cultures. The effects extended to the subsequent formation of more mature mesodermal lineages. We observed significant upregulation of cardiomyocyte marker Nkx2.5, and critically a decrease in the number of contaminant pluripotent cells after 12 days using a directed cardiomyocyte protocol. However, the impact of low oxygen preconditioning was to prime human cells for ectodermal lineage commitment during subsequent EB differentiation, with significant upregulation of Nestin and β3-tubulin. Our research demonstrates the importance of oxygen tension control during cell maintenance on the subsequent differentiation of both mouse and human PSCs, and highlights the differential effects.

Murine remote preconditioning increases glucose uptake and suppresses gluconeogenesis in hepatocytes via a brain-liver neurocircuit, leading to counteracting glucose intolerance.

PubMed

Kurabayashi, Atsushi; Tanaka, Chiharu; Matsumoto, Waka; Naganuma, Seiji; Furihata, Mutsuo; Inoue, Keiji; Kakinuma, Yoshihiko

2018-05-01

Our previous study revealed that cyclic hindlimb ischaemia-reperfusion (IR) activates cardiac acetylcholine (ACh) synthesis through the cholinergic nervous system and cell-derived ACh accelerates glucose uptake. However, the mechanisms regulating glucose metabolism in vivo remain unknown. We investigated the effects and mechanisms of IR in mice under pathophysiological conditions. Using IR-subjected male C57BL/6J mice, the effects of IR on blood sugar (BS), glucose uptake, central parasympathetic nervous system (PNS) activity, hepatic gluconeogenic enzyme expression and those of ACh on hepatocellular glucose uptake were assessed. IR decreased BS levels by 20% and increased c-fos immunoreactivity in the center of the PNS (the solitary tract and the dorsal motor vagal nucleus). IR specifically downregulated hepatic gluconeogenic enzyme expression and activities (glucose-6-phosphatase and phosphoenolpyruvate carboxykinase) and accelerated hepatic glucose uptake. Transection of a hepatic vagus nerve branch decreased this uptake and reversed BS decrease. Suppressed gluconeogenic enzyme expression was reversed by intra-cerebroventricular administration of a choline acetyltransferase inhibitor. Moreover, IR significantly attenuated hyperglycaemia in murine model of type I and II diabetes mellitus. IR provides another insight into a therapeutic modality for diabetes mellitus due to regulating gluconeogenesis and glucose-uptake and advocates an adjunctive mode rectifying disturbed glucose metabolism. Copyright © 2018 Elsevier B.V. All rights reserved.

Role of erythropoietin in the brain

PubMed Central

Noguchi, Constance Tom; Asavaritikrai, Pundit; Teng, Ruifeng; Jia, Yi

2007-01-01

Multi-tissue erythropoietin receptor (EPO-R) expression provides for erythropoietin (EPO) activity beyond its known regulation of red blood cell production. This review highlights the role of EPO and EPO-R in brain development and neuroprotection. EPO-R brain expression includes neural progenitor cells (NPC), neurons, glial cells and endothelial cells. EPO is produced in brain in a hypoxia sensitive manner, stimulates NPC proliferation and differentiation, and neuron survival, and contributes to ischemic preconditioning. Mice lacking EPO or EPO-R exhibit increased neural cell apoptosis during development before embryonic death due to severe anemia. EPO administration provides neural protection in animal models of brain ischemia and trauma, reducing the extent of injury and damage. EPO stimulation of endothelial cells contributes to neuroprotection and is of particular importance since only low levels of EPO appear to cross the blood-brain barrier when administered at high dose intravenously. The therapeutic potential of EPO for brain ischemia/trauma and neurodegenerative diseases has shown promise in early clinical trial and awaits further validation. PMID:17482474

Relationships among alcoholic liver disease, antioxidants, and antioxidant enzymes

PubMed Central

Han, Kyu-Ho; Hashimoto, Naoto; Fukushima, Michihiro

2016-01-01

Excessive consumption of alcoholic beverages is a serious cause of liver disease worldwide. The metabolism of ethanol generates reactive oxygen species, which play a significant role in the deterioration of alcoholic liver disease (ALD). Antioxidant phytochemicals, such as polyphenols, regulate the expression of ALD-associated proteins and peptides, namely, catalase, superoxide dismutase, glutathione, glutathione peroxidase, and glutathione reductase. These plant antioxidants have electrophilic activity and may induce antioxidant enzymes via the Kelch-like ECH-associated protein 1-NF-E2-related factor-2 pathway and antioxidant responsive elements. Furthermore, these antioxidants are reported to alleviate cell injury caused by oxidants or inflammatory cytokines. These phenomena are likely induced via the regulation of mitogen-activating protein kinase (MAPK) pathways by plant antioxidants, similar to preconditioning in ischemia-reperfusion models. Although the relationship between plant antioxidants and ALD has not been adequately investigated, plant antioxidants may be preventive for ALD because of their electrophilic and regulatory activities in the MAPK pathway. PMID:26755859

Relationships among alcoholic liver disease, antioxidants, and antioxidant enzymes.

PubMed

Han, Kyu-Ho; Hashimoto, Naoto; Fukushima, Michihiro

2016-01-07

Excessive consumption of alcoholic beverages is a serious cause of liver disease worldwide. The metabolism of ethanol generates reactive oxygen species, which play a significant role in the deterioration of alcoholic liver disease (ALD). Antioxidant phytochemicals, such as polyphenols, regulate the expression of ALD-associated proteins and peptides, namely, catalase, superoxide dismutase, glutathione, glutathione peroxidase, and glutathione reductase. These plant antioxidants have electrophilic activity and may induce antioxidant enzymes via the Kelch-like ECH-associated protein 1-NF-E2-related factor-2 pathway and antioxidant responsive elements. Furthermore, these antioxidants are reported to alleviate cell injury caused by oxidants or inflammatory cytokines. These phenomena are likely induced via the regulation of mitogen-activating protein kinase (MAPK) pathways by plant antioxidants, similar to preconditioning in ischemia-reperfusion models. Although the relationship between plant antioxidants and ALD has not been adequately investigated, plant antioxidants may be preventive for ALD because of their electrophilic and regulatory activities in the MAPK pathway.

Inaccurate Metacognitive Monitoring and Its Effects on Metacognitive Control and Task Outcomes in Self-Regulated L2 Learning

ERIC Educational Resources Information Center

Ranalli, Jim

2018-01-01

Accurate metacognitive monitoring of one's own knowledge or performance is a precondition for self-regulated learning; monitoring informs metacognitive control, which in turn affects task outcomes. Studies of monitoring accuracy and its connection to knowledge and performance are common in psychology and educational research but rare in instructed…

Tetanus toxoid and CCL3 improve dendritic cell vaccines in mice and glioblastoma patients.

PubMed

Mitchell, Duane A; Batich, Kristen A; Gunn, Michael D; Huang, Min-Nung; Sanchez-Perez, Luis; Nair, Smita K; Congdon, Kendra L; Reap, Elizabeth A; Archer, Gary E; Desjardins, Annick; Friedman, Allan H; Friedman, Henry S; Herndon, James E; Coan, April; McLendon, Roger E; Reardon, David A; Vredenburgh, James J; Bigner, Darell D; Sampson, John H

2015-03-19

After stimulation, dendritic cells (DCs) mature and migrate to draining lymph nodes to induce immune responses. As such, autologous DCs generated ex vivo have been pulsed with tumour antigens and injected back into patients as immunotherapy. While DC vaccines have shown limited promise in the treatment of patients with advanced cancers including glioblastoma, the factors dictating DC vaccine efficacy remain poorly understood. Here we show that pre-conditioning the vaccine site with a potent recall antigen such as tetanus/diphtheria (Td) toxoid can significantly improve the lymph node homing and efficacy of tumour-antigen-specific DCs. To assess the effect of vaccine site pre-conditioning in humans, we randomized patients with glioblastoma to pre-conditioning with either mature DCs or Td unilaterally before bilateral vaccination with DCs pulsed with Cytomegalovirus phosphoprotein 65 (pp65) RNA. We and other laboratories have shown that pp65 is expressed in more than 90% of glioblastoma specimens but not in surrounding normal brain, providing an unparalleled opportunity to subvert this viral protein as a tumour-specific target. Patients given Td had enhanced DC migration bilaterally and significantly improved survival. In mice, Td pre-conditioning also enhanced bilateral DC migration and suppressed tumour growth in a manner dependent on the chemokine CCL3. Our clinical studies and corroborating investigations in mice suggest that pre-conditioning with a potent recall antigen may represent a viable strategy to improve anti-tumour immunotherapy.

Tetanus toxoid and CCL3 improve DC vaccines in mice and glioblastoma patients

PubMed Central

Mitchell, Duane A.; Batich, Kristen A.; Gunn, Michael D.; Huang, Min-Nung; Sanchez-Perez, Luis; Nair, Smita K.; Congdon, Kendra L.; Reap, Elizabeth A.; Archer, Gary E.; Desjardins, Annick; Friedman, Allan H.; Friedman, Henry S.; Herndon, James E.; Coan, April; McLendon, Roger E.; Reardon, David A.; Vredenburgh, James J.; Bigner, Darell D.; Sampson, John H.

2015-01-01

Upon stimulation, dendritic cells (DCs) mature and migrate to draining lymph nodes to induce immune responses1. As such, autologous DCs generated ex vivo have been pulsed with tumor antigens and injected back into patients as immunotherapy. While DC vaccines have shown limited promise in the treatment of patients with advanced cancers2–4 including glioblastoma (GBM),5–7 the factors dictating DC vaccine efficacy remain poorly understood. Here we demonstrate that pre-conditioning the vaccine site with a potent recall antigen such as tetanus/diphtheria (Td) toxoid can significantly improve the lymph node homing and efficacy of tumor antigen-specific DCs. To assess the impact of vaccine site pre-conditioning in humans, we randomized patients with GBM to pre-conditioning with mature DCs8 or Td unilaterally before bilateral vaccination with Cytomegalovirus pp65 RNA-pulsed DCs. We and other laboratories have shown that pp65 is expressed in > 90% of GBM specimens but not surrounding normal brain9–12, providing an unparalleled opportunity to subvert this viral protein as a tumor-specific target. Patients given Td had enhanced DC migration bilaterally and significantly improved survival. In mice, Td pre-conditioning also enhanced bilateral DC migration and suppressed tumor growth in a manner dependent on the chemokine CCL3. Our clinical studies and corroborating investigations in mice suggest that pre-conditioning with a potent recall antigen may represent a viable strategy to improve antitumor immunotherapy. PMID:25762141

Metformin preconditioned adipose derived mesenchymal stem cells is a better option for the reversal of diabetes upon transplantation.

PubMed

Shree, Nitya; Bhonde, Ramesh R

2016-12-01

Metformin is used worldwide as an insulin sensitizer. Adipose derived mesenchymal stem cells have shown promising results in the reducing hyperglycemia. We examined whether preconditioning of adipose derived mesenchymal stem cells (ASCs) with metformin could have a better therapeutic value for the reversal of type 2 diabetes. We compared the effect of metformin, ASCs and metformin preconditioned ASCs (MetASCs) in high fat diet induced C57BL/6 mice by injecting the cells intramuscularly only once where as metformin was given at a concentration of 300mg per kg body weight orally daily. Fasting glucose was measured every week for 4 weeks. At the end of the study insulin, triglycerides, IL6 and oxidised LDL were evaluated from the serum. Gene expression studies were performed for muscle (GLUT4) and liver tissues (IL6 and PAI1).There was a remarkable decrease in hyperglycemia within two weeks of injection by MetASCs as compared to metformin and ASCs alone. A significant decrement of hyperinsulinemia, triglyceridemia, serum IL6 and oxidised LDL were observed at the end of the study. Gene expression studies for muscle tissue revealed the drastic upregulation of GLUT4 gene levels in the MetASCs group indicating enhanced glucose uptake in muscle. Liver tissue analysed for the genes involved in inflammation viz. IL6 and PAI1 showed significant downregulation in the MetASCs group as compared to the other groups. This is a first report demonstrating the synergistic effect of metformin preconditioning of ASCs leading to reversal of hyperglycemia, hyperinsulinemia and triglyceridemia. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Heme oxygenase-1 mediates the protective effects of ischemic preconditioning on mitigating lung injury induced by lower limb ischemia-reperfusion in rats.

PubMed

Peng, Tsui-Chin; Jan, Woan-Ching; Tsai, Pei-Shan; Huang, Chun-Jen

2011-05-15

Lower limb ischemia-reperfusion (I/R) imposes oxidative stress, elicits inflammatory response, and subsequently induces acute lung injury. Ischemic preconditioning (IP), a process of transient I/R, mitigates the acute lung injury induced by I/R. We sought to elucidate whether the protective effects of IP involve heme oxygenase-1 (HO-1). Adult male rats were randomized to receive I/R, I/R plus IP, I/R plus IP plus the HO-1 inhibitor tin protoporphyrin (SnPP) (n = 12 in each group). Control groups were run simultaneously. I/R was induced by applying rubber band tourniquet high around each thigh for 3 h followed by reperfusion for 3 h. To achieve IP, three cycles of bilateral lower limb I/R (i.e., ischemia for 10 min followed by reperfusion for 10 min) were performed. IP was performed immediately before I/R. After sacrifice, degree of lung injury was determined. Histologic findings, together with assays of leukocyte infiltration (polymorphonuclear leukocytes/alveoli ratio and myeloperoxidase activity) and lung water content (wet/dry weight ratio), confirmed that I/R induced acute lung injury. I/R also caused significant inflammatory response (increases in chemokine, cytokine, and prostaglandin E(2) concentrations), imposed significant oxidative stress (increases in nitric oxide and malondialdehyde concentrations), and up-regulated HO-1 expression in lung tissues. IP significantly enhanced HO-1 up-regulation and, in turn, mitigated oxidative stress, inflammatory response, and acute lung injury induced by I/R. In addition, the protective effects of IP were counteracted by SnPP. The protective effects of IP on mitigating acute lung injury induced by lower limb I/R are mediated by HO-1. Copyright © 2011 Elsevier Inc. All rights reserved.

The Role of Ethylene and Cold Temperature in the Regulation of the Apple POLYGALACTURONASE1 Gene and Fruit Softening1[W][OA

PubMed Central

Tacken, Emma; Ireland, Hilary; Gunaseelan, Kularajathevan; Karunairetnam, Sakuntala; Wang, Daisy; Schultz, Keith; Bowen, Judith; Atkinson, Ross G.; Johnston, Jason W.; Putterill, Jo; Hellens, Roger P.; Schaffer, Robert J.

2010-01-01

Fruit softening in apple (Malus × domestica) is associated with an increase in the ripening hormone ethylene. Here, we show that in cv Royal Gala apples that have the ethylene biosynthetic gene ACC OXIDASE1 suppressed, a cold treatment preconditions the apples to soften independently of added ethylene. When a cold treatment is followed by an ethylene treatment, a more rapid softening occurs than in apples that have not had a cold treatment. Apple fruit softening has been associated with the increase in the expression of cell wall hydrolase genes. One such gene, POLYGALACTURONASE1 (PG1), increases in expression both with ethylene and following a cold treatment. Transcriptional regulation of PG1 through the ethylene pathway is likely to be through an ETHYLENE-INSENSITIVE3-like transcription factor, which increases in expression during apple fruit development and transactivates the PG1 promoter in transient assays in the presence of ethylene. A cold-related gene that resembles a COLD BINDING FACTOR (CBF) class of gene also transactivates the PG1 promoter. The transactivation by the CBF-like gene is greatly enhanced by the addition of exogenous ethylene. These observations give a possible molecular mechanism for the cold- and ethylene-regulated control of fruit softening and suggest that either these two pathways act independently and synergistically with each other or cold enhances the ethylene response such that background levels of ethylene in the ethylene-suppressed apples is sufficient to induce fruit softening in apples. PMID:20237022

Transcriptome comparisons shed light on the pre-condition and potential barrier for C4 photosynthesis evolution in eudicots.

PubMed

Tao, Yimin; Lyu, Ming-Ju Amy; Zhu, Xin-Guang

2016-05-01

C4 photosynthesis evolved independently from C3 photosynthesis in more than 60 lineages. Most of the C4 lineages are clustered together in the order Poales and the order Caryophyllales while many other angiosperm orders do not have C4 species, suggesting the existence of biological pre-conditions in the ancestral C3 species that facilitate the evolution of C4 photosynthesis in these lineages. To explore pre-adaptations for C4 photosynthesis evolution, we classified C4 lineages into the C4-poor and the C4-rich groups based on the percentage of C4 species in different genera and conducted a comprehensive comparison on the transcriptomic changes between the non-C4 species from the C4-poor and the C4-rich groups. Results show that species in the C4-rich group showed higher expression of genes related to oxidoreductase activity, light reaction components, terpene synthesis, secondary cell synthesis, C4 cycle related genes and genes related to nucleotide metabolism and senescence. In contrast, C4-poor group showed up-regulation of a PEP/Pi translocator, genes related to signaling pathway, stress response, defense response and plant hormone metabolism (ethylene and brassinosteroid). The implications of these transcriptomic differences between the C4-rich and C4-poor groups to C4 evolution are discussed.

Intestinal ischemic preconditioning reduces liver ischemia reperfusion injury in rats

PubMed Central

XUE, TONG-MIN; TAO, LI-DE; ZHANG, JIE; ZHANG, PEI-JIAN; LIU, XIA; CHEN, GUO-FENG; ZHU, YI-JIA

2016-01-01

The aim of the current study was to investigate whether intestinal ischemic preconditioning (IP) reduces damage to the liver during hepatic ischemia reperfusion (IR). Sprague Dawley rats were used to model liver IR injury, and were divided into the sham operation group (SO), IR group and IP group. The results indicated that IR significantly increased Bax, caspase 3 and NF-κBp65 expression levels, with reduced expression of Bcl-2 compared with the IP group. Compared with the IR group, the levels of AST, ALT, MPO, MDA, TNF-α and IL-1 were significantly reduced in the IP group. Immunohistochemistry for Bcl-2 and Bax indicated that Bcl-2 expression in the IP group was significantly increased compared with the IR group. In addition, IP reduced Bax expression compared with the IR group. The average liver injury was worsened in the IR group and improved in the IP group, as indicated by the morphological evaluation of liver tissues. The present study suggested that IP may alleviates apoptosis, reduce the release of pro-inflammatory cytokines, ameloriate reductions in liver function and reduce liver tissue injury. To conclude, IP provided protection against hepatic IR injury. PMID:26821057

Research report: the effects of hyperbaric oxygen preconditioning on myocardial biomarkers of cardioprotection in patients having coronary artery bypass graft surgery.

PubMed

Jeysen, Zivan Yogaratnam; Gerard, Laden; Levant, Guvendik; Cowen, Mike; Cale, Alex; Griffin, Steve

2011-01-01

We have previously conducted and reported on the primary endpoint of a clinical study which demonstrated that hyperbaric oxygen (HBO2) preconditioning consisting of two 30-minute intervals of 100% oxygen at 2.4 atmospheres absolute (ATA) prior to coronary artery bypass graft (CABG) surgery leads to an improvement in left ventricular stroke work (LVSW) 24 hours following CABG. In that study, 81 patients were randomized to treatment with HBO2 (HBO2; n = 41) or routine treatment (Control Group; n = 40) prior to surgery. The objective of this manuscript is to further report on the result of the exploratory secondary endpoints from that study, specifically the effects of HBO2 preconditioning on biomarkers of myocardial protection. Intraoperative right atrial biopsies were assessed, via an Enzyme Linked ImmunoSorbent Assay (ELISA), for the expression of eNOS and HSP72. In this study, no significant differences were observed between the groups with respect to the quantity of myocardial eNOS and HSP72. However, in the HBO2 Group, following ischemia and reperfusion, the quantities of myocardial eNOS and HSP72 were increased. This suggests that HBO2 preconditioning in this group of patients may be capable of inducing endogenous cardioprotection following ischemic reperfusion injury (IRI).

Pre-Conditioning with Low-Level Laser (Light) Therapy: Light Before the Storm

PubMed Central

Agrawal, Tanupriya; Gupta, Gaurav K.; Rai, Vikrant; Carroll, James D.; Hamblin, Michael R.

2014-01-01

Pre-conditioning by ischemia, hyperthermia, hypothermia, hyperbaric oxygen (and numerous other modalities) is a rapidly growing area of investigation that is used in pathological conditions where tissue damage may be expected. The damage caused by surgery, heart attack, or stroke can be mitigated by pre-treating the local or distant tissue with low levels of a stress-inducing stimulus, that can induce a protective response against subsequent major damage. Low-level laser (light) therapy (LLLT) has been used for nearly 50 years to enhance tissue healing and to relieve pain, inflammation and swelling. The photons are absorbed in cytochrome(c) oxidase (unit four in the mitochondrial respiratory chain), and this enzyme activation increases electron transport, respiration, oxygen consumption and ATP production. A complex signaling cascade is initiated leading to activation of transcription factors and up- and down-regulation of numerous genes. Recently it has become apparent that LLLT can also be effective if delivered to normal cells or tissue before the actual insult or trauma, in a pre-conditioning mode. Muscles are protected, nerves feel less pain, and LLLT can protect against a subsequent heart attack. These examples point the way to wider use of LLLT as a pre-conditioning modality to prevent pain and increase healing after surgical/medical procedures and possibly to increase athletic performance. PMID:25552961

Effects of intermittent hypobaric hypoxia preconditioning on the expression of neuroglobin and Bcl-2 in the rat hippocampal CA1 area following ischemia-reperfusion.

PubMed

Wu, Q; Yu, K X; Ma, Q S; Liu, Y N

2015-09-09

This study was aimed at understanding the effect of intermittent hypobaric hypoxia preconditioning (IHHP) on neuroglobin (NGB) and Bcl-2 expression in the hippocampal CA1 region of rats following global cerebral ischemia-reperfusion. Wistar rats were randomly divided into sham, IHHP control, global cerebral ischemia-reperfusion (IR group), and IHHP+IR groups. The four-vessel occlusion rat model of Pulsinelli was used for the IR groups, in which the common carotid artery was occluded for 8 min before reperfusion. Thionin and immunohistochemical staining were used to observe NGB and Bcl-2 expression in the hippocampal CA1 region. Data was analyzed using the SPSS software. There was a significant increase in the number of surviving cells in the hippocampal CA1 region of the IHHP+IR group (119.5 ± 14) compared to the IR group (41.7 ± 3.8) (P < 0.05). There was a significant increase in the expression of NGB and Bcl-2 in the hippocampal CA1 region of the IHHP+IR group compared to the IR group. By upregulating hippocampal NGB and Bcl-2 expression, IHHP may play a role in neural protection by reducing hippocampal neuronal apoptosis following IR.

Endothelial expression of selectins during endotoxin preconditioning.

PubMed

Bauer, P; Welbourne, T; Shigematsu, T; Russell, J; Granger, D N

2000-12-01

Although bacterial endotoxins [lipopolysaccharide (LPS)] can confer tissue resistance to subsequent inflammatory insults, the mechanisms that underlie this LPS-preconditioning (LPS-PC) response remain poorly defined. The dual-radiolabeled monoclonal antibody technique was used to examine whether LPS-PC alters the upregulation (protein) of E- and P-selectins after subsequent LPS challenge. In the gut of wild-type (C57BL/6J) mice, LPS-PC was associated with a reduction in E- (66%) and P-selectin (33%) expression. A similar reduction in E-selectin expression was observed in mutant mice that were genetically deficient in either the endothelial or inducible isoform of nitric oxide synthase or that overexpressed the human gene for Cu/Zn superoxide dismutase. Severe combined immunodeficient mice, genetically devoid of lymphocytes, did exhibit partial inhibition of the LPS-PC response. We conclude that 1) LPS-PC can be demonstrated for E- and P-selectins in some vascular beds (e.g., gut), 2) the mechanism(s) underlying this blunted selectin response does not include a major role for either nitric oxide and superoxide, and 3) circulating lymphocytes may contribute to the LPS-PC response.

Cobalt chloride attenuates hypobaric hypoxia induced vascular leakage in rat brain: Molecular mechanisms of action of cobalt chloride

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

Kalpana, S.; Dhananjay, S.; Anju, B.

2008-09-15

This study reports the efficacy of cobalt preconditioning in preventing hypobaric hypoxia induced vascular leakage (an indicator of cerebral edema) using male Sprague-Dawley rats as model system. Exposure of animals to hypobaric hypoxia led to a significant increase in vascular leakage, reactive oxygen species (ROS), nitric oxide (NO), and vascular endothelial growth factor (VEGF) levels. There was a marked increase in Nuclear Factor {kappa}B (NF{kappa}B) DNA binding activity and levels of pro-inflammatory cytokines such as Monocyte chemoattractant protein (MCP-1), Interferon-{gamma} (IFN-{gamma}), Interleukin-1 (IL-1), and Tumor Necrosis Factor-{alpha} (TNF-{alpha}) and cell adhesion molecules such as Vascular Cell Adhesion Molecule-1 (VCAM-1), andmore » P-selectin. Chemical preconditioning by cobalt for 7 days (12.5 mg Co/kg b.w., oral) significantly attenuated cerebral vascular leakage and the expression of inflammatory mediators induced by hypoxia. Administration of NF{kappa}B inhibitor, curcumin (50 mg/kg b.w.; i.p.) appreciably inhibited hypoxia induced vascular leakage indicating the involvement of NF{kappa}B in causing vascular leakage. Interestingly, cobalt when administered at 12.5 mg Co/kg b.w. (i.p.), 1 h before hypoxia could not prevent the vascular leakage indicating that cobalt per se did not have an effect on NF{kappa}B. The lower levels of NF{kappa}B observed in the brains of cobalt administered animals might be due to higher levels of antioxidant and anti-inflammatory proteins (hemeoxygenase-1 and metallothionein). To conclude cobalt preconditioning inhibited hypobaric hypoxia induced cerebral vascular leakage by lowering NF{kappa}B DNA binding activity and its regulated pro-inflammatory mediators. This is contemplated to be mediated by cobalt induced reduction in ROS/NO and increase in HO-1 and MT.« less

Sulforaphane preconditioning of the Nrf2/HO-1 defense pathway protects the cerebral vasculature against blood-brain barrier disruption and neurological deficits in stroke.

PubMed

Alfieri, Alessio; Srivastava, Salil; Siow, Richard C M; Cash, Diana; Modo, Michel; Duchen, Michael R; Fraser, Paul A; Williams, Steven C R; Mann, Giovanni E

2013-12-01

Disruption of the blood-brain barrier (BBB) and cerebral edema are the major pathogenic mechanisms leading to neurological dysfunction and death after ischemic stroke. The brain protects itself against infarction via activation of endogenous antioxidant defense mechanisms, and we here report the first evidence that sulforaphane-mediated preactivation of nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream target heme oxygenase-1 (HO-1) in the cerebral vasculature protects the brain against stroke. To induce ischemic stroke, Sprague-Dawley rats were subjected to 70 min middle cerebral artery occlusion (MCAo) followed by 4, 24, or 72 h reperfusion. Nrf2 and HO-1 protein expression was upregulated in cerebral microvessels of peri-infarct regions after 4-72 h, with HO-1 preferentially associated with perivascular astrocytes rather than the cerebrovascular endothelium. In naïve rats, treatment with sulforaphane increased Nrf2 expression in cerebral microvessels after 24h. Upregulation of Nrf2 by sulforaphane treatment prior to transient MCAo (1h) was associated with increased HO-1 expression in perivascular astrocytes in peri-infarct regions and cerebral endothelium in the infarct core. BBB disruption, lesion progression, as analyzed by MRI, and neurological deficits were reduced by sulforaphane pretreatment. As sulforaphane pretreatment led to a moderate increase in peroxynitrite generation, we suggest that hormetic preconditioning underlies sulforaphane-mediated protection against stroke. In conclusion, we propose that pharmacological or dietary interventions aimed to precondition the brain via activation of the Nrf2 defense pathway in the cerebral microvasculature provide a novel therapeutic approach for preventing BBB breakdown and neurological dysfunction in stroke. Crown Copyright © 2013. Published by Elsevier Inc. All rights reserved.

Progressive exercise preconditioning protects against circulatory shock during experimental heatstroke.

PubMed

Hung, Ching-Hsia; Chang, Nen-Chung; Cheng, Bor-Chih; Lin, Mao-Tsun

2005-05-01

Heat shock protein (HSP) 72 expression protects against arterial hypotension in rat heatstroke. HSP72 can also be induced in multiple organs, including hearts from rats with endurance exercise. We validated the hypothesis that progressive exercise preconditioning may confer cardiovascular protection during heatstroke by inducing the overexpression of HSP72 in multiple organs. To deal with the matter, we assessed the effects of heatstroke on mean arterial pressure, heart rate, cardiac output, stroke volume, total peripheral vascular resistance, colonic temperature, blood gases, and serum or tissue levels of tumor necrosis factor-alpha (TNF-alpha) in urethane-anesthetized rats pretreated without or with progressive exercise training for 1, 2, or 3 weeks. In addition, HSP72 expression in multiple organs was determined in different groups of animals. Heatstroke was induced by exposing the rats to a high blanket temperature (43 degrees C); the moment at which mean arterial pressure decreased from the peak value was taken as the time of heatstroke onset. Previous exercise training for 3 weeks, but not 1 or 2 weeks, conferred significant protection against hyperthermia, arterial hypotension, decreased cardiac output, decreased stroke volume, decreased peripheral vascular resistance, and increased levels of serum or tissue TNF-alpha during heatstroke and correlated with overexpression of HSP72 in multiple organs, including heart, liver, and adrenal gland. However, 10 days after 3 weeks of progressive exercise training, when HSP72 expression in multiple organs returned to basal values, the beneficial effects exerted by 3 weeks of exercise training were no longer observed. These results strongly suggest that HSP72 preconditioning with progressive exercise training protects against hyperthermia, circulatory shock, and TNF-alpha overproduction during heatstroke.

Allogeneic Stem Cells Alter Gene Expression and Improve Healing of Distal Limb Wounds in Horses

PubMed Central

Textor, Jamie A.; Clark, Kaitlin C.; Walker, Naomi J.; Aristizobal, Fabio A.; Kol, Amir; LeJeune, Sarah S.; Bledsoe, Andrea; Davidyan, Arik; Gray, Sarah N.; Bohannon‐Worsley, Laurie K.; Woolard, Kevin D.

2017-01-01

Abstract Distal extremity wounds are a significant clinical problem in horses and humans and may benefit from mesenchymal stem cell (MSC) therapy. This study evaluated the effects of direct wound treatment with allogeneic stem cells, in terms of gross, histologic, and transcriptional features of healing. Three full‐thickness cutaneous wounds were created on each distal forelimb in six healthy horses, for a total of six wounds per horse. Umbilical cord‐blood derived equine MSCs were applied to each wound 1 day after wound creation, in one of four forms: (a) normoxic‐ or (b) hypoxic‐preconditioned cells injected into wound margins, or (c) normoxic‐ or (d) hypoxic‐preconditioned cells embedded in an autologous fibrin gel and applied topically to the wound bed. Controls were one blank (saline) injected wound and one blank fibrin gel‐treated wound per horse. Data were collected weekly for 6 weeks and included wound surface area, thermography, gene expression, and histologic scoring. Results indicated that MSC treatment by either delivery method was safe and improved histologic outcomes and wound area. Hypoxic‐preconditioning did not offer an advantage. MSC treatment by injection resulted in statistically significant increases in transforming growth factor beta and cyclooxygenase‐2 expression at week 1. Histologically, significantly more MSC‐treated wounds were categorized as pro‐healing than pro‐inflammatory. Wound area was significantly affected by treatment: MSC‐injected wounds were consistently smaller than gel‐treated or control wounds. In conclusion, MSC therapy shows promise for distal extremity wounds in horses, particularly when applied by direct injection into the wound margin. stem cells translational medicine 2018;7:98–108 PMID:29063737

Role of Rbp1 in the acquired chill-light tolerance of cyanobacteria.

PubMed

Tan, Xiaoming; Zhu, Tao; Shen, Si; Yin, Chuntao; Gao, Hong; Xu, Xudong

2011-06-01

Synechocystis sp. strain PCC 6803 cultured at 30°C losses viability quickly under chill (5°C)-light stress but becomes highly tolerant to the stress after conditioning at 15°C (Y. Yang, C. Yin, W. Li, and X. Xu, J. Bacteriol. 190:1554-1560, 2008). Hypothetically, certain factors induced during preconditioning are involved in acquisition of chill-light tolerance. In this study, Rbp1 (RNA-binding protein 1) rather than Rbp2 was found to be accumulated during preconditioning, and the accumulation of Rbp1 was correlated with the increase of chill-light tolerance. Inactivation of its encoding gene rbp1 led to a great reduction in the acquired chill-light tolerance, while ectopic expression of rbp1 enabled the cyanobacterium to survive the chill-light stress without preconditioning. Microarray analyses suggested that the Rbp1-dependent chill-light tolerance may not be based on its influence on mRNA abundance of certain genes. Similarly to that in Synechocystis, the Rbp1 homologue(s) can be accumulated in Microcystis cells collected from a subtropic lake in low-temperature seasons. Rbp1 is the first factor shown to be both accumulated early during preconditioning and directly involved in development of chill-light tolerance in Synechocystis. Its accumulation may greatly enhance the overwintering capability in certain groups of cyanobacteria.

Hypoxic-preconditioning enhances the regenerative capacity of neural stem/progenitors in subventricular zone of newborn piglet brain.

PubMed

Ara, Jahan; De Montpellier, Sybille

2013-09-01

Perinatal hypoxia-ischemia (HI) results in brain injury, whereas mild hypoxic episodes result in preconditioning, which can significantly reduce the vulnerability of the brain to subsequent severe hypoxia-ischemia. Hypoxic-preconditioning (PC) has been shown to enhance cell survival and differentiation of progenitor cells in the central nervous system (CNS). The purpose of this study was to determine whether pretreatment with PC prior to HI stimulates subventricular zone (SVZ) proliferation and neurogenesis in newborn piglets. One-day-old piglets were subjected to PC (8% O2/92% N2) for 3h and 24h later were exposed to HI produced by combination of hypoxia (5% FiO2) for a pre-defined period of 30min and ischemia induced by a period of 10min of hypotension. Here we demonstrate that SVZ derived neural stem/progenitor cells (NSPs) from PC, HI and PC+HI piglets proliferated as neurospheres, expressed neural progenitor and neurodevelopmental markers, and that greater proportion of the spheres generated are multipotential. Neurosphere assay revealed that preconditioning pretreatment increased the number of NSP-derived neurospheres in SVZ following HI compared to normoxic and HI controls. NSPs from preconditioned SVZ generated twice as many neurons and astrocytes in vitro. Injections with 5-Bromo-2-deoxyuridine (BrdU) after PC revealed a robust proliferative response within the SVZ that continued for one week. PC also increased neurogenesis in vivo, doublecortin positive cells with migratory profiles were observed streaming from the SVZ to striatum and neocortex. These findings show that the induction of proliferation and neurogenesis by PC might be a positive adaptation for an efficient repair and plasticity in the event of a hypoxic-ischemic insult. Copyright © 2013 Elsevier B.V. All rights reserved.

Preconditioning Triggered by Carbon Monoxide (CO) Provides Neuronal Protection Following Perinatal Hypoxia-Ischemia

PubMed Central

Widerøe, Marius; Alves, Paula M.; Vercelli, Alessandro; Vieira, Helena L. A.

2012-01-01

Perinatal hypoxia-ischemia is a major cause of acute mortality in newborns and cognitive and motor impairments in children. Cerebral hypoxia-ischemia leads to excitotoxicity and necrotic and apoptotic cell death, in which mitochondria play a major role. Increased resistance against major damage can be achieved by preconditioning triggered by subtle insults. CO, a toxic molecule that is also generated endogenously, may have a role in preconditioning as low doses can protect against inflammation and apoptosis. In this study, the role of CO-induced preconditioning on neurons was addressed in vitro and in vivo. The effect of 1 h of CO treatment on neuronal death (plasmatic membrane permeabilization and chromatin condensation) and bcl-2 expression was studied in cerebellar granule cells undergoing to glutamate-induced apoptosis. CO's role was studied in vivo in the Rice-Vannucci model of neonatal hypoxia-ischemia (common carotid artery ligature +75 min at 8% oxygen). Apoptotic cells, assessed by Nissl staining were counted with a stereological approach and cleaved caspase 3-positive profiles in the hippocampus were assessed. Apoptotic hallmarks were analyzed in hippocampal extracts by Western Blot. CO inhibited excitotoxicity-induced cell death and increased Bcl-2 mRNA in primary cultures of neurons. In vivo, CO prevented hypoxia-ischemia induced apoptosis in the hippocampus, limited cytochrome c released from mitochondria and reduced activation of caspase-3. Still, Bcl-2 protein levels were higher in hippocampus of CO pre-treated rat pups. Our results show that CO preconditioning elicits a molecular cascade that limits neuronal apoptosis. This could represent an innovative therapeutic strategy for high-risk cerebral hypoxia-ischemia patients, in particular neonates. PMID:22952602

Effects of in vitro low oxygen tension preconditioning of adipose stromal cells on their in vivo chondrogenic potential: application in cartilage tissue repair.

PubMed

Portron, Sophie; Merceron, Christophe; Gauthier, Olivier; Lesoeur, Julie; Sourice, Sophie; Masson, Martial; Fellah, Borhane Hakim; Geffroy, Olivier; Lallemand, Elodie; Weiss, Pierre; Guicheux, Jérôme; Vinatier, Claire

2013-01-01

Multipotent stromal cell (MSC)-based regenerative strategy has shown promise for the repair of cartilage, an avascular tissue in which cells experience hypoxia. Hypoxia is known to promote the early chondrogenic differentiation of MSC. The aim of our study was therefore to determine whether low oxygen tension could be used to enhance the regenerative potential of MSC for cartilage repair. MSC from rabbit or human adipose stromal cells (ASC) were preconditioned in vitro in control or chondrogenic (ITS and TGF-β) medium and in 21 or 5% O2. Chondrogenic commitment was monitored by measuring COL2A1 and ACAN expression (real-time PCR). Preconditioned rabbit and human ASC were then incorporated into an Si-HPMC hydrogel and injected (i) into rabbit articular cartilage defects for 18 weeks or (ii) subcutaneously into nude mice for five weeks. The newly formed tissue was qualitatively and quantitatively evaluated by cartilage-specific immunohistological staining and scoring. The phenotype of ASC cultured in a monolayer or within Si-HPMC in control or chondrogenic medium and in 21 or 5% O2 was finally evaluated using real-time PCR. 5% O2 increased the in vitro expression of chondrogenic markers in ASC cultured in induction medium. Cells implanted within Si-HPMC hydrogel and preconditioned in chondrogenic medium formed a cartilaginous tissue, regardless of the level of oxygen. In addition, the 3D in vitro culture of ASC within Si-HPMC hydrogel was found to reinforce the pro-chondrogenic effects of the induction medium and 5% O2. These data together indicate that although 5% O2 enhances the in vitro chondrogenic differentiation of ASC, it does not enhance their in vivo chondrogenesis. These results also highlight the in vivo chondrogenic potential of ASC and their potential value in cartilage repair.

In vitro/vivo drug release and anti-diabetic cardiomyopathy properties of curcumin/PBLG-PEG-PBLG nanoparticles.

PubMed

Tong, Fei; Chai, Rongkui; Jiang, Haiying; Dong, Bo

2018-01-01

The objective of this study was to survey the therapeutic function of curcumin-encapsulated poly(gamma-benzyl l-glutamate)-poly(ethylene glycol)-poly(gammabenzyl l-glutamate) (PBLG-PEG-PBLG) (P) on diabetic cardiomyopathy (DCM) via cross regulation effect of calcium-sensing receptor (CaSR) and endogenous cystathionine-γ-lyase (CSE)/hydrogen sulfide (H 2 S). Diabetic rats were preconditioned with 20 mg/kg curcumin or curcumin/P complex continuously for 8 weeks. The blood and myocardiums were collected, the level of serum H 2 S was observed, and the [Ca 2+ ] i content was measured in myocardial cells, and hematoxylin-eosin, CaSR, CSE, and calmodulin (CaM) expression were detected. Both curcumin and curcumin/P pretreatment alleviated pathological morphological damage of myocardium, increased H 2 S and [Ca 2+ ] i levels, and upregulated the expression of CaSR, CSE, and CaM as compared to DCM group, while curcumin/P remarkably augmented this effect. PBLG-PEG-PBLG could improve water-solubility and bioactivity of curcumin and curcumin/PBLG-PEG-PBLG significantly alleviated diabetic cardiomyopathy.

TRPV4 channels: physiological and pathological role in cardiovascular system.

PubMed

Randhawa, Puneet Kaur; Jaggi, Amteshwar Singh

2015-11-01

TRPV4 channels are non-selective cation channels permeable to Ca(2+), Na(+), and Mg(2+) ions. Recently, TRPV4 channels have received considerable attention as these channels are widely expressed in the cardiovascular system including endothelial cells, cardiac fibroblasts, vascular smooth muscles, and peri-vascular nerves. Therefore, these channels possibly play a pivotal role in the maintenance of cardiovascular homeostasis. TRPV4 channels critically regulate flow-induced arteriogenesis, TGF-β1-induced differentiation of cardiac fibroblasts into myofibroblasts, and heart failure-induced pulmonary edema. These channels also mediate hypoxia-induced increase in proliferation and migration of pulmonary artery smooth muscle cells and progression of pulmonary hypertension. These channels also maintain flow-induced vasodilation and preserve vascular function by directly activating Ca(2+)-dependent KCa channels. Furthermore, these may also induce vasodilation and maintain blood pressure indirectly by evoking the release of NO, CGRP, and substance P. The present review discusses the evidences and the potential mechanisms implicated in diverse responses including arteriogenesis, cardiac remodeling, congestive heart failure-induced pulmonary edema, pulmonary hypertension, flow-induced dilation, regulation of blood pressure, and hypoxic preconditioning.

Remote ischemic preconditioning with a specialized protocol activates the non-neuronal cardiac cholinergic system and increases ATP content in the heart.

PubMed

Oikawa, Shino; Mano, Asuka; Takahashi, Rina; Kakinuma, Yoshihiko

2015-11-01

Ischemic preconditioning (IPC) renders the targeted organ resistant to prolonged ischemic insults, leading to organoprotection. Among several means to achieve IPC, we reported that remote ischemic preconditioning (RIPC) activates the non-neuronal cardiac cholinergic system (NNCCS) to accelerate de novo ACh synthesis in cardiomyocytes. In the current study, we aimed to optimize a specific protocol to most efficiently activate NNCCS using RIPC. In this study, we elucidated that the protocol with 3 min of ischemia repeated three times increased cardiac ChAT expression (139.2 ± 0.4%; P < 0.05) as well as ACh (14.2 ± 2.0× 10(-8) M; P< 0.05) and ATP content (2.13 ± 0.19 μmol/g tissue; P < 0.05) in the heart. Moreover, in the specific protocol, several characteristic responses against energy starvation and for obtaining adequate energy were observed; therefore, it is suggested that RIPC evokes a robust response by the heart to activate NNCCS through the modification of energy metabolism. Copyright © 2015 Elsevier B.V. All rights reserved.

The protective effects of ischemic preconditioning on rats with renal ischemia-reperfusion injury and the effects on the expression of Bcl-2 and Bax.

PubMed

Shen, Sheng; Zhou, Jiexue; Meng, Shandong; Wu, Jiaqing; Ma, Juan; Zhu, Chunli; Deng, Gengguo; Liu, Dong

2017-11-01

The aim of the present study was to investigate the protective effects of ischemic preconditioning on rats with renal ischemia-reperfusion injury and the effects on the expression of Bcl-2 and Bax. Thirty-six SD rats were randomly divided into three groups (n=12) including sham operation (S) group, ischemia-reperfusion group (I/R) group and ischemic preconditioning (IP) group. After anesthesia with intraperitoneal injection of chloral hydrate, bilateral renal pedicles were clipped for 45 min, followed by perfusion for 6 h to establish the I/R model. Both kidneys in rats of S group were separated and exposed for 45 min, but renal pedicles were not clipped. In IP group, bilateral renal pedicles were clipped for 5 min, followed by perfusion for 5 min, this procedure was repeated 3 times. Then bilateral renal pedicles were clipped for 45 min, followed by perfusion for 6 h. Blood samples were collected and rats were sacrificed to collect renal tissue. Levels of serum creatinine (Cr) and blood urea nitrogen (BUN) were measured. Activity of superoxide dismutase (SOD) was measured by xanthine oxidase assay. Degree of renal injury was evaluated by H&E staining. TUNEL kit was used to detect the number of apoptotic cells in renal tissue. Expression levels of Bcl-2 and Bax were detected by semi-quantitative PCR and western blot analysis at mRNA and protein levels, respectively. Results showed that levels of Cr and BUN in I/R and IP groups were significantly higher than those in S group, and levels of Cr and BUN in I/R group were significantly higher than that in IP group (P<0.05). Activity of SOD in I/R group and IP group were significantly lower than those in S group, and activity of SOD in I/R group were significantly lower than those in IP group (P<0.05). H&E staining showed that, compared with S group, renal injury in the I/R and IP groups was more serious than that in the S group, and I/R group was more serious than the IP group (P<0.05). TUNEL apoptosis assay showed that number of apoptotic cells in IP and I/R groups were significantly higher than that in the S group (P<0.01). Semi-quantitative PCR and western blot analysis showed that, compared with the S group, expression levels of Bcl-2 mRNA and protein were significantly decreased, expression levels of Bax mRNA and protein were significantly increased, and the ratio of Bcl-2/Bax was significantly decreased in the IP and I/R groups (P<0.01). Compared with the I/R group, expression level of Bcl-2 was significantly increased, the level of Bax was significantly deceased, and the ratio of Bcl-2/Bax was significantly increased in the IP group (P<0.01). As a result, ischemic preconditioning can protect rats with renal ischemia-reperfusion injury possibly by increasing the expression level of Bcl-2 and decreasing the expression level of Bax.

Impact of repeated asenapine treatment on FosB/ΔFosB expression in neurons of the rat central nucleus of the amygdala: colocalization with corticoliberine (CRH) and effect of an unpredictable mild stress preconditioning.

PubMed

Majercikova, Z; Kiss, A

2015-04-01

FosB/ΔFosB expression in the central amygdalar nucleus (CeA) in response to repeated asenapine (ASE) treatment (an atypical antipsychotic used for the treatment of schizophrenia) was studied in normal rats and rats preconditioned with chronic unpredictable variable mild stress (CMS). The goal of this study was to reveal whether repeated ASE treatment for 14 days may: 1) induce FosB/ΔFosB expression in the amygdala, 2) activate CRH-synthesizing neurons in the CeA, and 3) interfere with 21 days lasting concomitant CMS preconditioning. Four groups of animals were studied: controls and ASE-, CMS-, and CMS+ASE-treated ones. CMS consisted of the restrain, social isolation, crowding, swimming, and cold and lasted 21 days. The ASE and CMS+ASE groups were from the 7th day of the experiment treated with ASE (0.3 mg/kg, subcutaneously - s.c.) twice a day, i.e. together for 14 days. Controls and CMS groups were treated with saline (300 µl/rat, s.c.) twice a day for 14 days. All the animals were sacrificed on the 22nd day, i.e. 16-18 hours after the last treatments. Single FosB/ΔFosB, FosB/ΔFosB colocalizations with CRH, and CRH immunolabeled perikarya were investigated in the CeA using a combined light and fluorescent immunohistochemistry. The distribution aspect of the black FosB/ΔFosB profiles was homogeneous over the whole CeA and no significant differences in the number of FosB/ΔFosB profiles between the individual groups of the rats really occurred. The level of colocalization pattern of FosB/ΔFosB in CRH perikarya was also very similar between the individual groups and in each case it reached approximately 10% of double-labeling. No differences were also seen in the number of CRH immunolabeled perikarya. The density of CRH nerve projections within the CeA was very alike in the individual groups of animals investigated. The study provides a new anatomical/functional finding about the lack of the stimulatory effect of the repeated ASE treatment on the expression of FosB/ΔFosB, FosB/ΔFosB/CRH colocalizations, and CRH immunolabeled perikarya number in the CeA. In addition, CMS preconditioning itself neither stimulated nor inhibited FosB/ΔFosB expression, nor altered the impact of ASE on the activity of CRH neurons in the CeA.

14 CFR 272.10 - Conditions applicable to carriers serving a subsidized market.

Code of Federal Regulations, 2010 CFR

2010-01-01

... TRANSPORTATION (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS ESSENTIAL AIR SERVICE TO THE FREELY ASSOCIATED STATES... precondition to the payment of compensation necessary to maintain essential air service, whether or not the affected carrier is itself receiving subsidy compensation in the market, if it finds that: (1) Essential...

Induction of tolerance and prolongation of islet allograft survival by syngeneic hematopoietic stem cell transplantation in mice.

PubMed

Yang, Shi-feng; Xue, Wu-jun; Lu, Wan-hong; Xie, Li-yi; Yin, Ai-ping; Zheng, Jin; Sun, Ji-ping; Li, Yang

2015-10-01

Syngeneic or autologous hematopoietic stem cells transplantation (HSCT) has been proposed to treat autoimmune diseases because of its immunosuppressive and immunomodulatory effects, which can also contribute to posttransplant antirejection therapy. In this study, we explored the tolerogenic effect of syngeneic HSCT on prolonging islet allograft survival. C57BL/6 mice received syngeneic HSCT plus preconditioning with sublethal irradiation. Then islets of BALB/c mice were transplanted into the renal subcapsular of C57BL/6 mice after chemically induced into diabetes. HSCT mice exhibited improved islet allograft survival and increased serum insulin compared to control mice. Islet allografts of HSCT mice displayed lower level lymphocyte infiltration and stronger insulin staining than control mice. T cells of HSCT mice proliferated poorly in response to allogeneic splenocytes compared to control mice. Mice appeared reversed interferon-γ (IFN-γ)/interleukin-4 (IL-4) ratio to a Th2 immune deviation after syngeneic HSCT. The percentage of CD8(+) T cells was lower, while percentage of CD4(+)CD25(+)Foxp3(+) T regulatory cells (Tregs) was higher in HSCT mice than control mice. HSCT mice showed higher percentage of CTLA-4(+) T cells and expression of CTLA-4 mRNA than control mice. Targeting of CTLA-4 by intraperitoneal injection of anti-CTLA-4 mAb abrogated the effect of syngeneic HSCT on prolonging islet allograft survival, inhibiting activity of T cells in response to alloantigen, promoting Th1 to Th2 immune deviation and up regulating CD4(+)CD25(+)Foxp3(+) Tregs. Syngeneic HSCT plus preconditioning of sublethal irradiation induces tolerance and improves islet allograft survival in fully mismatched mice model. Th1 to Th2 immune deviation, increased CD4(+)CD25(+)Foxp3(+) Tregs and up-regulation of CTLA-4 maybe contribute to the tolerogenic effect induced by syngeneic HSCT. Copyright © 2015 Elsevier B.V. All rights reserved.

[Reduction of the immunological rejection in composite tissue allotransplantation by heat stress preconditioning].

PubMed

Schorr, N; Sauerbier, M; Germann, G; Gebhard, M M; Ofer, N

2011-12-01

In spite of great advances in the field of composite tissue allotransplantations (CTA), there is still a major need for optimisation in terms of immunosuppression. Heat shock proteins are produced as a reaction of the body during a stress situation. Once elevated, they protect against a second stress and reduce ischaemia-reperfusion injury within transplantations. In the literature the effect of heat shock and HSP70 on rejection after CTA has not been described. The purpose of this experimental study was to examine the effect of heat shock proteins on rejection in a rat model of CTA. Evaluated was the effect of preconditioning by prior heat stress. Brown Norway rats were systemically heated to a core temperature of 42 °C in order to up-regulate HSP70. The expression of HSP70 in muscle was measured by Western blot analysis and showed a peak 24 h after heat shock. Allogeneic hindlimb transplantations were performed between Brown Norway rats (donor) and Lewis rats (recipients). Group 1 (n=12) was preheated 24 h prior to transplantation. In group 2 (n=12) the transplantation was performed without prior heat shock. Group 3 (n=6) was used as a control group with syngeneic hindlimb transplantations between Lewis rats. Postoperatively the appearance of the transplanted hindlimb was evaluated every 12 h. The beginning of rejection was defined when plantar erythema and foot oedema could be observed at the same time. To verify these discrete signs of rejection, the observation was continued for a further 24 h. In this time erythema and oedema spread over the whole transplanted hindlimb. The rat was sacrificed after specimens of skin and muscle had been taken for histological assessment. The rejection in group 1 (with preconditioning heat shock) began after 4.83±0.44 days, in group 2 (without heat shock) already after 3.88±0.53 days. The difference between these groups was significant because of the small standard deviation (Whitney-Mann U test: p<0.01). In our model of allogeneic composite tissue transplantation, a heat shock and subsequent up-regulation of HSP70 led to a significant delay of the immunological rejection. As the graft rejection is an important item influencing the outcome of allogeneic transplantations, these results represent an option to improve the final functional outcome of composite tissue allotransplantations. © Georg Thieme Verlag KG Stuttgart · New York.

Global gene expression analysis of transgenic, mannitol-producing, and salt-tolerant Arabidopsis thaliana indicates widespread changes in abiotic and biotic stress-related genes

PubMed Central

Chan, Zhulong; Grumet, Rebecca; Loescher, Wayne

2011-01-01

Mannitol is a putative osmoprotectant contributing to salt tolerance in several species. Arabidopsis plants transformed with the mannose-6-phosphate reductase (M6PR) gene from celery were dramatically more salt tolerant (at 100 mM NaCl) as exhibited by reduced salt injury, less inhibition of vegetative growth, and increased seed production relative to the wild type (WT). When treated with 200 mM NaCl, transformants produced no seeds, but did bolt, and exhibited less chlorosis/necrosis and greater survival and dry weights than the WT. Without salt there were no M6PR effects on growth or phenotype, but expression levels of 2272 genes were altered. Many fewer differences (1039) were observed between M6PR and WT plants in the presence of salt, suggesting that M6PR pre-conditioned the plants to stress. Previous work suggested that mannitol is an osmoprotectant, but mannitol levels are invariably quite low, perhaps inadequate for osmoprotectant effects. In this study, transcriptome analysis reveals that the M6PR transgene activated the downstream abscisic acid (ABA) pathway by up-regulation of ABA receptor genes (PYL4, PYL5, and PYL6) and down-regulation of protein phosphatase 2C genes (ABI1 and ABI2). In the M6PR transgenic lines there were also increases in transcripts related to redox and cell wall-strengthening pathways. These data indicate that mannitol-enhanced stress tolerance is due at least in part to increased expression of a variety of stress-inducible genes. PMID:21821598

Hypoxic Conditioned Medium From Human Adipose-Derived Stem Cells Promotes Mouse Liver Regeneration Through JAK/STAT3 Signaling

PubMed Central

Lee, Sang Chul; Jeong, Hye Jin; Lee, Sang Kuon

2016-01-01

Adipose-derived stem cells (ASCs) mainly exert their function by secreting materials that are collectively termed the secretome. Despite recent attention to the secretome as an alternative to stem cell therapy, the culture conditions for generating optimal secretome contents have not been determined. Therefore, we investigated the role of hypoxic-conditioned media (HCM) from ASCs. Normoxic-conditioned media (NCM) and HCM were obtained after culturing ASCs in 20% O2 or 1% O2 for 24 hours, respectively. Subsequently, partially hepatectomized mice were infused with saline, control medium, NCM, or HCM, and then sera and liver specimens were obtained for analyses. Hypoxia (1% O2) significantly increased mRNA expression of mediators from ASCs, including interleukin-6 (IL-6), tumor necrosis factor α (TNF-α), hepatocyte growth factor (HGF), and vascular endothelial growth factor (VEGF). HCM infusion significantly increased the number of Ki67-positive cells in the liver (p < .05). HCM infusion significantly increased phospho-signal transducer and activator of transcription 3 (STAT3) and decreased suppressor of cytokine signaling 3 (SOCS3) expression in the liver (p < .05). To determine the role of IL-6 in liver regeneration, we then performed IL-6 RNA interference study. Conditioned media (CM) obtained from ASCs, which were transfected with either siIL-6 or siControl, were administered to partially hepatectomized mice. The siIL-6 CM groups exhibited lower liver proliferation (Ki67-positive cells) and markers of regeneration (protein expression of proliferating cell nuclear antigen, p-STAT3, HGF, and VEGF and liver weights) than the siControl CM groups (p < .05). Taken together, hypoxic preconditioning of ASCs increased expression of mediators promoting anti-inflammatory and regenerative responses. The liver regenerative effects of HCM appear to be mediated by persistent and uninhibited expression of STAT3 in the liver, which results from decreased expression of SOCS3. Significance In this study, it was found that treatment with the medium from hypoxic-preconditioned adipose-derived stem cells (ASCs) increased the viability of hepatotoxic hepatocytes and enhance liver regeneration in partially hepatectomized mice. In addition, the researchers first revealed that the hepatoprotective effects of hypoxic-conditioned media are mediated by persistent and uninhibited expression of signal transducer and activator of transcription 3 in the liver, which result from a decreased expression of suppressor of cytokine signaling 3. Therefore, the hypoxic preconditioning of ASCs is expected to play a crucial role in regenerative medicine by optimizing the production of a highly effective secretome from ASCs. PMID:27102647

Achaete-Scute Homolog 1 Expression Controls Cellular Differentiation of Neuroblastoma

PubMed Central

Kasim, Mumtaz; Heß, Vicky; Scholz, Holger; Persson, Pontus B.; Fähling, Michael

2016-01-01

Neuroblastoma, the major cause of infant cancer deaths, results from fast proliferation of undifferentiated neuroblasts. Treatment of high-risk neuroblastoma includes differentiation with retinoic acid (RA); however, the resistance of many of these tumors to RA-induced differentiation poses a considerable challenge. Human achaete-scute homolog 1 (hASH1) is a proneural basic helix-loop-helix transcription factor essential for neurogenesis and is often upregulated in neuroblastoma. Here, we identified a novel function for hASH1 in regulating the differentiation phenotype of neuroblastoma cells. Global analysis of 986 human neuroblastoma datasets revealed a negative correlation between hASH1 and neuron differentiation that was independent of the N-myc (MYCN) oncogene. Using RA to induce neuron differentiation in two neuroblastoma cell lines displaying high and low levels of hASH1 expression, we confirmed the link between hASH1 expression and the differentiation defective phenotype, which was reversed by silencing hASH1 or by hypoxic preconditioning. We further show that hASH1 suppresses neuronal differentiation by inhibiting transcription at the RA receptor element. Collectively, our data indicate hASH1 to be key for understanding neuroblastoma resistance to differentiation therapy and pave the way for hASH1-targeted therapies for augmenting the response of neuroblastoma to differentiation therapy. PMID:28066180

The influence of rapamycin on the early cardioprotective effect of hypoxic preconditioning on cardiomyocytes

PubMed Central

Wang, Jiang; Maimaitili, YiLiyaer; Yu, Jin; Guo, Hai; Ma, Hai-Ping; Chen, Chun-ling

2016-01-01

Introduction The purpose of this study was to examine the effects of rapamycin on the cardioprotective effect of hypoxic preconditioning (HPC) and on the mammalian target of rapamycin (mTOR)-mediated hypoxia-inducible factor 1 (HIF-1) signaling pathway. Material and methods Primary cardiomyocytes were isolated from rat pups and underwent rapamycin and/or HPC, followed by hypoxia/re-oxygenation (H/R) injury. Cell viability and cell injury were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays, and qRT-PCR was used to measure HIF-1α and mTOR mRNA expression. A Langendorff heart perfusion model was conducted to observe the effect of rapamycin. Results Rapamycin treatment nearly abolished the cardioprotective effect of HPC in cardiomyocytes, reduced cell viability (p = 0.007) and increased cell damage (p = 0.032). HIF-1α and mTOR mRNA expression increased in cardiomyocytes undergoing I/R injury within 2 h after HPC. After rapamycin treatment, mTOR mRNA expression and HPC-induced HIF-1α mRNA expression were both reduced (p < 0.001). A Langendorff heart perfusion model in rat hearts showed that rapamycin greatly attenuated the cardioprotective effect of HPC in terms of heart rate, LVDP, and dp/dtmax (all, p < 0.029). Conclusions Rapamycin, through inhibition of mTOR, reduces the elevated HIF-1α expression at an early stage of HPC, and attenuates the early cardioprotective effect of HPC. PMID:28721162

Protein kinase C epsilon regulates mitochondrial pools of Nampt and NAD following resveratrol and ischemic preconditioning in the rat cortex

PubMed Central

Morris-Blanco, Kahlilia C; Cohan, Charles H; Neumann, Jake T; Sick, Thomas J; Perez-Pinzon, Miguel A

2014-01-01

Preserving mitochondrial pools of nicotinamide adenine dinucleotide (NAD) or nicotinamide phosphoribosyltransferase (Nampt), an enzyme involved in NAD production, maintains mitochondrial function and confers neuroprotection after ischemic stress. However, the mechanisms involved in regulating mitochondrial-localized Nampt or NAD have not been defined. In this study, we investigated the roles of protein kinase C epsilon (PKCɛ) and AMP-activated protein kinase (AMPK) in regulating mitochondrial pools of Nampt and NAD after resveratrol or ischemic preconditioning (IPC) in the cortex and in primary neuronal-glial cortical cultures. Using the specific PKCɛ agonist ψɛRACK, we found that PKCɛ induced robust activation of AMPK in vitro and in vivo and that AMPK was required for PKCɛ-mediated ischemic neuroprotection. In purified mitochondrial fractions, PKCɛ enhanced Nampt levels in an AMPK-dependent manner and was required for increased mitochondrial Nampt after IPC or resveratrol treatment. Analysis of intrinsic NAD autofluorescence using two-photon microscopy revealed that PKCɛ modulated NAD in the mitochondrial fraction. Further assessments of mitochondrial NAD concentrations showed that PKCɛ has a key role in regulating the mitochondrial NAD+/nicotinamide adenine dinucleotide reduced (NADH) ratio after IPC and resveratrol treatment in an AMPK- and Nampt-dependent manner. These findings indicate that PKCɛ is critical to increase or maintain mitochondrial Nampt and NAD after pathways of ischemic neuroprotection in the brain. PMID:24667915

Anti-Apoptotic Effects of 3,3',5-Triiodo-L-Thyronine in the Liver of Brain-Dead Rats.

PubMed

Rebolledo, Rolando A; Van Erp, Anne C; Ottens, Petra J; Wiersema-Buist, Janneke; Leuvenink, Henri G D; Romanque, Pamela

2015-01-01

Thyroid hormone treatment in brain-dead organ donors has been extensively studied and applied in the clinical setting. However, its clinical applicability remains controversial due to a varying degree of success and a lack of mechanistic understanding about the therapeutic effects of 3,3',5-Triiodo-L-thyronine (T3). T3 pre-conditioning leads to anti-apoptotic and pro-mitotic effects in liver tissue following ischemia/reperfusion injury. Therefore, we aimed to study the effects of T3 pre-conditioning in the liver of brain-dead rats. Brain death (BD) was induced in mechanically ventilated rats by inflation of a Fogarty catheter in the epidural space. T3 (0.1 mg/kg) or vehicle was administered intraperitoneally 2 h prior to BD induction. After 4 h of BD, serum and liver tissue were collected. RT-qPCR, routine biochemistry, and immunohistochemistry were performed. Brain-dead animals treated with T3 had lower plasma levels of AST and ALT, reduced Bax gene expression, and less hepatic cleaved Caspase-3 activation compared to brain-dead animals treated with vehicle. Interestingly, no differences in the expression of inflammatory genes (IL-6, MCP-1, IL-1β) or the presence of pro-mitotic markers (Cyclin-D and Ki-67) were found in brain-dead animals treated with T3 compared to vehicle-treated animals. T3 pre-conditioning leads to beneficial effects in the liver of brain-dead rats as seen by lower cellular injury and reduced apoptosis, and supports the suggested role of T3 hormone therapy in the management of brain-dead donors.

Preconditioning of skeletal myoblast-based engineered tissue constructs enables functional coupling to myocardium in vivo

PubMed Central

Treskes, Philipp; Neef, Klaus; Srinivasan, Sureshkumar Perumal; Halbach, Marcel; Stamm, Christof; Cowan, Douglas; Scherner, Maximilian; Madershahian, Navid; Wittwer, Thorsten; Hescheler, Jürgen; Wahlers, Thorsten; Choi, Yeong-Hoon

2015-01-01

Objective Skeletal myoblasts fuse to form functional syncytial myotubes as an integral part of the skeletal muscle. During this differentiation process, expression of proteins for mechanical and electrical integration is seized, which is a major drawback for the application of skeletal myoblasts in cardiac regenerative cell therapy, because global heart function depends on intercellular communication. Methods Mechanically preconditioned engineered tissue constructs containing neonatal mouse skeletal myoblasts were transplanted epicardially. A Y-chromosomal specific polymerase chain reaction (PCR) was undertaken up to 10 weeks after transplantation to confirm the presence of grafted cells. Histologic and electrophysiologic analyses were carried out 1 week after transplantation. Results Cells within the grafted construct expressed connexin 43 at the interface to the host myocardium, indicating electrical coupling, confirmed by sharp electrode recordings. Analyses of the maximum stimulation frequency (5.65 ± 0.37 Hz), conduction velocity (0.087 ± 0.011 m/s) and sensitivity for pharmacologic conduction block (0.736 ± 0.080 mM 1-heptanol) revealed effective electrophysiologic coupling between graft and host cells, although significantly less robust than in native myocardial tissue (maximum stimulation frequency, 11.616 ± 0.238 Hz, P<.001; conduction velocity, 0.300 ± 0.057 m/s, P<.01; conduction block, 1.983 ± 0.077 mM 1-heptanol, P<.001). Conclusions Although untreated skeletal myoblasts cannot couple to cardiomyocytes, we confirm that mechanical preconditioning enables transplanted skeletal myoblasts to functionally interact with cardio-myocytes in vivo and, thus, reinvigorate the concept of skeletal myoblast-based cardiac cell therapy. PMID:25439779

ZFP580, a Novel Zinc-Finger Transcription Factor, Is Involved in Cardioprotection of Intermittent High-Altitude Hypoxia against Myocardial Ischemia-Reperfusion Injury

PubMed Central

Zhang, Wen-cheng; Wang, Tian-hui; Mai, Xia; Liu, Hong-tao; Xu, Rui-cheng

2014-01-01

Background ZFP580 is a novel C2H2 type zinc-finger transcription factor recently identified by our laboratory. We previously showed that ZFP580 may be involved in cell survival and growth. The aim of this study was to elucidate whether ZFP580 is involved in the cardioprotective effects of intermittent high-altitude (IHA) hypoxia against myocardial ischemia-reperfusion (I/R) injury. Methods and Results After rats were subjected to myocardial ischemia for 30 min followed by reperfusion, ZFP580 expression in the left ventricle was measured. ZFP580 protein expression was found to be up-regulated within 1 h and decreased at 2 h after reperfusion. Comparing normoxic and IHA hypoxia-adapted rats (5000 m, 6 h day−1, 6 weeks) following I/R injury (30 min ischemia and 2 h reperfusion), we found that adaptation to IHA hypoxia attenuated infarct size and plasma leakage of lactate dehydrogenase and creatine kinase-MB. In addition, ZFP580 expression in the myocardium was up-regulated by IHA hypoxia. Consistent with this result, ZFP580 expression was found to be significantly increased in cultured H9c2 myocardial cells in the hypoxic preconditioning group compared with those in the control group following simulated I/R injury (3 h simulated ischemic hypoxia and 2 h reoxygenation). To determine the role of ZFP580 in apoptosis, lentivirus-mediated gene transfection was performed in H9c2 cells 72 h prior to simulated I/R exposure. The results showed that ZFP580 overexpression significantly inhibited I/R-induced apoptosis and caspase-3 activation. H9c2 cells were pretreated with or without PD98059, an inhibitor of ERK1/2 phosphorylation, and Western blot results showed that PD98059 (10 µM) markedly suppressed I/R-induced up-regulation of ZFP580 expression. Conclusions Our findings demonstrate that the cardioprotective effect of IHA hypoxia against I/R injury is mediated via ZFP580, a downstream target of ERK1/2 signaling with anti-apoptotic roles in myocardial cells. PMID:24722354

Limb remote-preconditioning protects against focal ischemia in rats and contradicts the dogma of therapeutic time windows for preconditioning

PubMed Central

Ren, Chuancheng; Gao, Xuwen; Steinberg, Gary K.; Zhao, Heng

2009-01-01

Remote ischemic preconditioning is an emerging concept for stroke treatment, but its protection against focal stroke has not been established. We tested whether remote preconditioning, performed in the ipsilateral hind limb, protects against focal stroke and explored its protective parameters. Stroke was generated by a permanent occlusion of the left distal middle cerebral artery (MCA) combined with a 30 minute occlusion of the bilateral common carotid arteries (CCA) in male rats. Limb preconditioning was generated by 5 or 15 minute occlusion followed with the same period of reperfusion of the left hind femoral artery, and repeated for 2 or 3 cycles. Infarct was measured 2 days later. The results showed that rapid preconditioning with 3 cycles of 15 minutes performed immediately before stroke reduced infarct size from 47.7±7.6% of control ischemia to 9.8±8.6%; at 2 cycles of 15 minutes, infarct was reduced to 24.7±7.3%; at 2 cycles of 5 minutes, infarct was not reduced. Delayed preconditioning with 3 cycles of 15 minutes conducted 2 days before stroke also reduced infarct to 23.0 ±10.9%, but with 2 cycles of 15 minutes it offered no protection. The protective effects at these two therapeutic time windows of remote preconditioning are consistent with those of conventional preconditioning, in which the preconditioning ischemia is induced in the brain itself. Unexpectedly, intermediate preconditioning with 3 cycles of 15 minutes performed 12 hours before stroke also reduced infarct to 24.7±4.7%, which contradicts the current dogma for therapeutic time windows for the conventional preconditioning that has no protection at this time point. In conclusion, remote preconditioning performed in one limb protected against ischemic damage after focal cerebral ischemia. PMID:18201834

Effects of Remote Ischemic Preconditioning on Heme Oxygenase-1 Expression and Cutaneous Wound Repair

PubMed Central

Cremers, Niels A. J.; Wever, Kimberley E.; Wong, Ronald J.; van Rheden, René E. M.; Vermeij, Eline A.; van Dam, Gooitzen M.; Carels, Carine E.; Lundvig, Ditte M. S.; Wagener, Frank A. D. T. G.

2017-01-01

Skin wounds may lead to scar formation and impaired functionality. Remote ischemic preconditioning (RIPC) can induce the anti-inflammatory enzyme heme oxygenase-1 (HO-1) and protect against tissue injury. We aim to improve cutaneous wound repair by RIPC treatment via induction of HO-1. RIPC was applied to HO-1-luc transgenic mice and HO-1 promoter activity and mRNA expression in skin and several other organs were determined in real-time. In parallel, RIPC was applied directly or 24h prior to excisional wounding in mice to investigate the early and late protective effects of RIPC on cutaneous wound repair, respectively. HO-1 promoter activity was significantly induced on the dorsal side and locally in the kidneys following RIPC treatment. Next, we investigated the origin of this RIPC-induced HO-1 promoter activity and demonstrated increased mRNA in the ligated muscle, heart and kidneys, but not in the skin. RIPC did not change HO-1 mRNA and protein levels in the wound 7 days after cutaneous injury. Both early and late RIPC did not accelerate wound closure nor affect collagen deposition. RIPC induces HO-1 expression in several organs, but not the skin, and did not improve excisional wound repair, suggesting that the skin is insensitive to RIPC-mediated protection. PMID:28218659

Lipopolysaccharide hyporesponsiveness: protective or damaging response to the brain?

PubMed

Pardon, Marie Christine

2015-01-01

Lipopolysaccharide (LPS) endotoxins are widely used as experimental models of systemic bacterial infection and trigger robust inflammation by potently activating toll-like receptors 4 (TLR4) expressed on innate immune cells. Their ability to trigger robust neuroinflammation despite poor brain penetration can prove useful for the understanding of how inflammation induced by viral infections contributes to the pathogenesis of neurodegenerative diseases. A single LPS challenge often result in a blunted inflammatory response to subsequent stimulation by LPS and other TLR ligands, but the extent to which endotoxin tolerance occur in the brain requires further clarification. LPS is also thought to render the brain transiently resistant to subsequent brain injuries by attenuating the concomitant pro-inflammatory response. While LPS hyporesponsiveness and preconditioning are classically seen as protective mechanisms limiting the toxic effects of sustained inflammation, recent research casts doubt as to whether they have beneficial or detrimental roles on the brain and in neurodegenerative disease. These observations suggest that spatio-temporal aspects of the immune responses to LPS and the disease status are determinant factors. Endotoxin tolerance may lead to a late pro-inflammatory response with potential harmful consequences. And while reduced TLR4 signaling reduces the risk of neurodegenerative diseases, up-regulation of anti-inflammatory cytokines associated with LPS hyporesponsiveness can have deleterious consequences to the brain by inhibiting the protective phenotype of microglia, aggravating the progression of some neurodegenerative conditions such as Alzheimer's disease. Beneficial effects of LPS preconditioning, however appear to require a stimulation of anti-inflammatory mediators rather than an attenuation of the pro-inflammatory response.

Activation of Nrf2/HO-1 Pathway by Glycogen Synthase Kinase-3β Inhibition Attenuates Renal Ischemia/Reperfusion Injury in Diabetic Rats.

PubMed

Shen, Xiaohua; Hu, Bo; Xu, Guangtao; Chen, Fengjuan; Ma, Ruifen; Zhang, Nenghua; Liu, Jie; Ma, Xiaoqin; Zhu, Jia; Wu, Yuhong; Shen, Ruilin

2017-01-01

Diabetes mellitus can exacerbate renal ischemia-reperfusion (I/R) injury (RI/RI). The aim of the present study was to evaluate the protective effect of GSK-3β inhibition (TDZD-8) on I/R-induced renal injury through the Nrf2/HO-1 pathway in a streptozocin (STZ)-induced diabetic rat model. STZ-induced diabetic rats preconditioned with TDZD-8 and ZnPP were subjected to renal I/R. The extent of renal morphologic lesions. Renal function was assessed from blood urea nitrogen (BUN) and serum creatinine (Scr), as determined utlizing commercial kits. Oxidative stress and inflammatory activity in the kidney tissue was estimated from levels of malondialdehyde (MDA), interleukin-10 (IL-10), tumor necrosis factor-α (TNF-α), and nitric oxide (NO), as well as the activities of superoxide dismutase (SOD) and glutathione (GSH) using qRT-PCR and ELISA. The expressions of Nrf2, HO-1, Bcl-2 and NF-κB in the renal tissue were measured by qRT-PCR and western blotting. I/R-induced renal inflammation was reduced significantly by TDZD-8 pretreatment. Preconditioning with TDZD-8 suppressed NF-κB expression and enhanced Bcl-2 expression in the renal tissue. The upregulated level of malondialdehyde (MDA), and reduced activities of superoxide dismutase (SOD) and glutathione (GSH) in I/R-shocked rats were markedly restored by TDZD-8 pretreatment. Furthermore, pretreatment with TDZD-8 enhanced activation of the Nrf2/HO-1 pathway in the renal tissue of diabetic RI/RI rats. These findings suggest that preconditioning with TDZD-8 may protect the kidney from I/R-induced damage via the activation of the Nrf2/HO-1 pathway in STZ-induced diabetic rats. Further detailed studies are needed to further clarify the underlying mechanisms. © 2017 The Author(s). Published by S. Karger AG, Basel.

BMP-non-responsive Sca1+ CD73+ CD44+ mouse bone marrow derived osteoprogenitor cells respond to combination of VEGF and BMP-6 to display enhanced osteoblastic differentiation and ectopic bone formation.

PubMed

Madhu, Vedavathi; Li, Ching-Ju; Dighe, Abhijit S; Balian, Gary; Cui, Quanjun

2014-01-01

Clinical trials on fracture repair have challenged the effectiveness of bone morphogenetic proteins (BMPs) but suggest that delivery of mesenchymal stem cells (MSCs) might be beneficial. It has also been reported that BMPs could not increase mineralization in several MSCs populations, which adds ambiguity to the use of BMPs. However, an exogenous supply of MSCs combined with vascular endothelial growth factor (VEGF) and BMPs is reported to synergistically enhance fracture repair in animal models. To elucidate the mechanism of this synergy, we investigated the osteoblastic differentiation of cloned mouse bone marrow derived MSCs (D1 cells) in vitro in response to human recombinant proteins of VEGF, BMPs (-2, -4, -6, -9) and the combination of VEGF with BMP-6 (most potent BMP). We further investigated ectopic bone formation induced by MSCs pre-conditioned with VEGF, BMP-6 or both. No significant increase in mineralization, phosphorylation of Smads 1/5/8 and expression of the ALP, COL1A1 and osterix genes was observed upon addition of VEGF or BMPs alone to the cells in culture. The lack of CD105, Alk1 and Alk6 expression in D1 cells correlated with poor response to BMPs indicating that a greater care in the selection of MSCs is necessary. Interestingly, the combination of VEGF and BMP-6 significantly increased the expression of ALP, COL1A1 and osterix genes and D1 cells pre-conditioned with VEGF and BMP-6 induced greater bone formation in vivo than the non-conditioned control cells or the cells pre-conditioned with either VEGF or BMP-6 alone. This enhanced bone formation by MSCs correlated with higher CADM1 expression and OPG/RANKL ratio in the implants. Thus, combined action of VEGF and BMP on MSCs enhances osteoblastic differentiation of MSCs and increases their bone forming ability, which cannot be achieved through use of BMPs alone. This strategy can be effectively used for bone repair.

Loss of glycogen during preconditioning is not a prerequisite for protection of the rabbit heart.

PubMed

Weinbrenner, C; Wang, P; Downey, J M

1996-01-01

Depletion of glycogen has been proposed as the mechanism of protection from ischemic preconditioning. The hypothesis was tested by seeing whether pharmacological manipulation of preconditioning causes parallel changes in cardiac glycogen content. Five groups of isolated rabbit hearts were studied. Group 1 experienced 30 min of ischemia only. Group 2 (PC) was preconditioned with 5 min of global ischemia followed by 10 min of reperfusion. Group 3 was preconditioned with 5 min exposure to 400 nM bradykinin followed by a 10 min washout period. Group 4 experienced exposure to 10 microM adenosine followed by a 10 min washout period, and the fifth group was also preconditioned with 5 min ischemia and 10 min reperfusion but 100 microM 8-(p-sulfophenyl)theophylline (SPT), which blocks adenosine receptors, was included in the buffer to block preconditioning's protection. Transmural biopsies were taken before treatment, just prior to the 30 min period of global ischemia, and after 30 min of global ischemia. Glycogen in the samples was digested with amyloglucosidase and the resulting glucose was assayed. Baseline glycogen averaged 17.3 +/- 0.6 mumol glucose/g wet weight. After preconditioning glycogen decreased to 13.3 +/- 1.3 mumol glucose/g wet weight (p < 0.005 vs. baseline). Glycogen was similarly depleted after pharmacological preconditioning with adenosine (14.0 +/- 1.0 mumol glucose/g wet weight, p < 0.05 vs. baseline) suggesting a correlation. However, when preconditioning was performed in the presence of SPT, which blocks protection, glycogen was also depleted by the same amount (13.3 +/- 0.7 mumol glucose/g wet weight, p = ns vs. PC). Bradykinin, which also mimics preconditioning, caused no depletion of glycogen (16.3 +/- 0.8 mumol glucose/g wet weight, p = ns vs. baseline). Because preconditioning with bradykinin did not deplete glycogen and because glycogen continued to be low when protection from preconditioning was blocked with SPT, we conclude that loss of glycogen per se does not cause the protection of preconditioning.

Laparoscopic ischemic conditioning of the stomach increases neovascularization of the gastric conduit in patients undergoing esophagectomy for cancer.

PubMed

Pham, Thai H; Melton, Shelby D; McLaren, Patrick J; Mokdad, Ali A; Huerta, Sergio; Wang, David H; Perry, Kyle A; Hardaker, Hope L; Dolan, James P

2017-09-01

Gastric ischemic preconditioning has been proposed to improve blood flow and reduce the incidence of anastomotic complications following esophagectomy with gastric pull-up. This study aimed to evaluate the effect of prolonged ischemic preconditioning on the degree of neovascularization in the distal gastric conduit at the time of esophagectomy. A retrospective review of a prospectively maintained database identified 30 patients who underwent esophagectomy. The patients were divided into three groups: control (no preconditioning, n = 9), partial (short gastric vessel ligation only, n = 8), and complete ischemic preconditioning (left and short gastric vessel ligation, n = 13). Microvessel counts were assessed, using immunohistologic analysis to determine the degree of neovascularization at the distal gastric margin. The groups did not differ in age, gender, BMI, pathologic stage, or cancer subtype. Ischemic preconditioning durations were 163 ± 156 days for partial ischemic preconditioning, compared to 95 ± 50 days for complete ischemic preconditioning (P = 0.2). Immunohistologic analysis demonstrated an increase in microvessel counts of 29% following partial ischemic preconditioning (P = 0.3) and 67% after complete ischemic preconditioning (P < 0.0001), compared to controls. Our study indicates that prolonged ischemic preconditioning is safe and does not interfere with subsequent esophagectomy. Complete ischemic preconditioning increased neovascularization in the distal gastric conduit. © 2017 Wiley Periodicals, Inc.

The Hsp72 and Hsp90α mRNA Responses to Hot Downhill Running Are Reduced Following a Prior Bout of Hot Downhill Running, and Occur Concurrently within Leukocytes and the Vastus Lateralis.

PubMed

Tuttle, James A; Chrismas, Bryna C R; Gibson, Oliver R; Barrington, James H; Hughes, David C; Castle, Paul C; Metcalfe, Alan J; Midgley, Adrian W; Pearce, Oliver; Kabir, Chindu; Rayanmarakar, Faizal; Al-Ali, Sami; Lewis, Mark P; Taylor, Lee

2017-01-01

The leukocyte heat shock response (HSR) is used to determine individual's thermotolerance. The HSR and thermotolerance are enhanced following interventions such as preconditioning and/or acclimation/acclimatization. However, it is unclear whether the leukocyte HSR is an appropriate surrogate for the HSR in other tissues implicated within the pathophysiology of exertional heat illnesses (e.g., skeletal muscle), and whether an acute preconditioning strategy (e.g., downhill running) can improve subsequent thermotolerance. Physically active, non-heat acclimated participants were split into two groups to investigate the benefits of hot downhill running as preconditioning strategy. A hot preconditioning group (HPC; n = 6) completed two trials (HPC1 HOTDOWN and HPC2 HOTDOWN ) of 30 min running at lactate threshold (LT) on -10% gradient in 30°C and 50% relative humidity (RH) separated by 7 d. A temperate preconditioning group (TPC; n = 5) completed 30 min running at LT on a -1% gradient in 20°C and 50% (TPC1 TEMPFLAT ) and 7 d later completed 30 min running at LT on -10% gradient in 30°C and 50% RH (TPC2 HOTDOWN ). Venous blood samples and muscle biopsies (vastus lateralis; VL) were obtained before, immediately after, 3, 24, and 48 h after each trial. Leukocyte and VL Hsp72, Hsp90α, and Grp78 mRNA relative expression was determined via RT-QPCR. Attenuated leukocyte and VL Hsp72 (2.8 to 1.8 fold and 5.9 to 2.4 fold; p < 0.05) and Hsp90α mRNA (2.9 to 2.4 fold and 5.2 to 2.4 fold; p < 0.05) responses accompanied reductions ( p < 0.05) in physiological strain [exercising rectal temperature (-0.3°C) and perceived muscle soreness (~ -14%)] during HPC2 HOTDOWN compared to HPC1 HOTDOWN (i.e., a preconditioning effect). Both VL and leukocyte Hsp72 and Hsp90α mRNA increased ( p < 0.05) simultaneously following downhill runs and demonstrated a strong relationship ( p < 0.01) of similar magnitudes with one another. Hot downhill running is an effective preconditioning strategy which ameliorates physiological strain, soreness and Hsp72 and Hsp90α mRNA responses to a subsequent bout. Leukocyte and VL analyses are appropriate tissues to infer the extent to which the HSR has been augmented.

Isoflurane preconditioning protects neurons from male and female mice against oxygen and glucose deprivation and is modulated by estradiol only in neurons from female mice.

PubMed

Johnsen, D; Murphy, S J

2011-12-29

The volatile anesthetic, isoflurane, can protect the brain if administered before an insult such as an ischemic stroke. However, this protective "preconditioning" response to isoflurane is specific to males, with females showing an increase in brain damage following isoflurane preconditioning and subsequent focal cerebral ischemia. Innate cell sex is emerging as an important player in neuronal cell death, but its role in the sexually dimorphic response to isoflurane preconditioning has not been investigated. We used an in vitro model of isoflurane preconditioning and ischemia (oxygen and glucose deprivation, OGD) to test the hypotheses that innate cell sex dictates the response to isoflurane preconditioning and that 17β-estradiol attenuates any protective effect from isoflurane preconditioning in neurons via nuclear estrogen receptors. Sex-segregated neuron cultures derived from postnatal day 0-1 mice were exposed to either 0% or 3% isoflurane preconditioning for 1 h. In separate experiments, 17β-estradiol and the non-selective estrogen receptor antagonist ICI 182,780 were added 24 h before preconditioning and then removed at the end of the preconditioning period. Twenty-three hours after preconditioning, all cultures underwent 2 h of OGD. Twenty-four hours following OGD, cell viability was quantified using calcein-AM fluorescence. We observed that isoflurane preconditioning increased cell survival following subsequent OGD regardless of innate cell sex, but that the presence of 17β-estradiol before and during isoflurane preconditioning attenuated this protection only in female neurons independent of nuclear estrogen receptors. We also found that independent of preconditioning treatment, female neurons were less sensitive to OGD compared with male neurons and that transient treatment with 17β-estradiol protected both male and female neurons from subsequent OGD. More studies are needed to determine how cell type, cell sex, and sex steroids like 17β-estradiol may impact on anesthetic preconditioning and subsequent ischemic outcomes in the brain. Copyright © 2011 IBRO. Published by Elsevier Ltd. All rights reserved.

Preconditioning, postconditioning and their application to clinical cardiology.

PubMed

Kloner, Robert A; Rezkalla, Shereif H

2006-05-01

Ischemic preconditioning is a well-established phenomenon first described in experimental preparations in which brief episodes of ischemia/reperfusion applied prior to a longer coronary artery occlusion reduce myocardial infarct size. There are ample correlates of ischemic preconditioning in the clinical realm. Preconditioning mimetic agents that stimulate the biochemical pathways of ischemic preconditioning and protect the heart without inducing ischemia have been examined in numerous experimental studies. However, despite the effectiveness of ischemic preconditioning and preconditioning mimetics for protecting ischemic myocardium, there are no preconditioning-based therapies that are routinely used in clinical medicine at the current time. Part of the problem is the need to administer therapy prior to the known ischemic event. Other issues are that percutaneous coronary intervention technology has advanced so far (with the development of stents and drug-eluting stents) that ischemic preconditioning or preconditioning mimetics have not been needed in most interventional cases. Recent clinical trials such as AMISTAD I and II (Acute Myocardial Infarction STudy of ADenosine) suggest that some preconditioning mimetics may reduce myocardial infarct size when given along with reperfusion or, as in the IONA trial, have benefit on clinical events when administered chronically in patients with known coronary artery disease. It is possible that some of the benefit described for adenosine in the AMISTAD 1 and 2 trials represents a manifestation of the recently described postconditioning phenomenon. It is probable that postconditioning--in which reperfusion is interrupted with brief coronary occlusions and reperfusion sequences--is more likely than preconditioning to be feasible as a clinical application to patients undergoing percutaneous coronary intervention for acute myocardial infarction.

Augmentation of aerobic respiration and mitochondrial biogenesis in skeletal muscle by hypoxia preconditioning with cobalt chloride

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

Saxena, Saurabh; Shukla, Dhananjay; Bansal, Anju, E-mail: anjubansaldipas@gmail.com

High altitude/hypoxia training is known to improve physical performance in athletes. Hypoxia induces hypoxia inducible factor-1 (HIF-1) and its downstream genes that facilitate hypoxia adaptation in muscle to increase physical performance. Cobalt chloride (CoCl{sub 2}), a hypoxia mimetic, stabilizes HIF-1, which otherwise is degraded in normoxic conditions. We studied the effects of hypoxia preconditioning by CoCl{sub 2} supplementation on physical performance, glucose metabolism, and mitochondrial biogenesis using rodent model. The results showed significant increase in physical performance in cobalt supplemented rats without (two times) or with training (3.3 times) as compared to control animals. CoCl{sub 2} supplementation in rats augmentedmore » the biological activities of enzymes of TCA cycle, glycolysis and cytochrome c oxidase (COX); and increased the expression of glucose transporter-1 (Glut-1) in muscle showing increased glucose metabolism by aerobic respiration. There was also an increase in mitochondrial biogenesis in skeletal muscle observed by increased mRNA expressions of mitochondrial biogenesis markers which was further confirmed by electron microscopy. Moreover, nitric oxide production increased in skeletal muscle in cobalt supplemented rats, which seems to be the major reason for peroxisome proliferator activated receptor-gamma coactivator-1α (PGC-1α) induction and mitochondrial biogenesis. Thus, in conclusion, we state that hypoxia preconditioning by CoCl{sub 2} supplementation in rats increases mitochondrial biogenesis, glucose uptake and metabolism by aerobic respiration in skeletal muscle, which leads to increased physical performance. The significance of this study lies in understanding the molecular mechanism of hypoxia adaptation and improvement of work performance in normal as well as extreme conditions like hypoxia via hypoxia preconditioning. -- Highlights: ► We supplemented rats with CoCl{sub 2} for 15 days along with training. ► CoCl{sub 2} supplementation augmented endurance performance and aerobic respiration. ► It increased glucose uptake and metabolism in muscle. ► It enhanced mitochondrial biogenesis in red gastrocnemius muscle.« less

Implicit preconditioned WENO scheme for steady viscous flow computation

NASA Astrophysics Data System (ADS)

Huang, Juan-Chen; Lin, Herng; Yang, Jaw-Yen

2009-02-01

A class of lower-upper symmetric Gauss-Seidel implicit weighted essentially nonoscillatory (WENO) schemes is developed for solving the preconditioned Navier-Stokes equations of primitive variables with Spalart-Allmaras one-equation turbulence model. The numerical flux of the present preconditioned WENO schemes consists of a first-order part and high-order part. For first-order part, we adopt the preconditioned Roe scheme and for the high-order part, we employ preconditioned WENO methods. For comparison purpose, a preconditioned TVD scheme is also given and tested. A time-derivative preconditioning algorithm is devised and a discriminant is devised for adjusting the preconditioning parameters at low Mach numbers and turning off the preconditioning at intermediate or high Mach numbers. The computations are performed for the two-dimensional lid driven cavity flow, low subsonic viscous flow over S809 airfoil, three-dimensional low speed viscous flow over 6:1 prolate spheroid, transonic flow over ONERA-M6 wing and hypersonic flow over HB-2 model. The solutions of the present algorithms are in good agreement with the experimental data. The application of the preconditioned WENO schemes to viscous flows at all speeds not only enhances the accuracy and robustness of resolving shock and discontinuities for supersonic flows, but also improves the accuracy of low Mach number flow with complicated smooth solution structures.

Sulforaphane Inhibits Mitochondrial Permeability Transition and Oxidative Stress

PubMed Central

Greco, Tiffany; Shafer, Jonathan; Fiskum, Gary

2012-01-01

Exposure of mitochondria to oxidative stress and elevated Ca2+ promotes opening of the mitochondrial permeability transition pore (PTP), resulting in membrane depolarization, uncoupling of oxidative phosphorylation, and potentially cell death. This study tested the hypothesis that treatment of rats with sulforaphane (SFP), an activator of the Nrf2 pathway of antioxidant gene expression, increases the resistance of liver mitochondria to redox-regulated PTP opening and elevates mitochondrial levels of antioxidants. Rats were injected with SFP or drug vehicle and liver mitochondria were isolated 40 hr later. Respiring mitochondria actively accumulated added Ca2+, which was then released through PTP opening induced by agents that either cause an oxidized shift in the mitochondrial redox state or that directly oxidize protein thiol groups. SFP treatment of rats inhibited the rate of pro-oxidant-induced mitochondrial Ca2+ release and increased expression of the glutathione peroxidase/reductase system, thioredoxin, and malic enzyme. These results are the first to demonstrate that SFP treatment of animals increases liver mitochondrial antioxidant defenses and inhibits redox-sensitive PTP opening. This novel form of preconditioning could protect against a variety of pathologies that include oxidative stress and mitochondrial dysfunction in their etiologies. PMID:21986339

Placental Expression of Glucose Transporter Proteins in Pregnancies Complicated by Gestational and Pregestational Diabetes Mellitus.

PubMed

Stanirowski, Paweł Jan; Szukiewicz, Dariusz; Pazura-Turowska, Monika; Sawicki, Włodzimierz; Cendrowski, Krzysztof

2018-04-01

Gestational diabetes mellitus and pregestational diabetes mellitus constitute carbohydrate metabolism disorders, which, if not diagnosed and adequately treated, lead to serious and often life-threatening pregnancy complications. According to a recently formulated hypothesis, some diabetes-related complications, such as fetal macrosomia, may be the result of disturbances in the transplacental transport of nutrients-in particular, excessive maternal-fetal glucose transfer. Throughout pregnancy, glucose flux across the placenta is mediated by the group of facilitative glucose transporters (GLUT), the expression of which in different placental compartments is the precondition for effective glucose uptake from maternal blood and its subsequent transfer to the fetal circulation. In diabetes-complicated pregnancies, the location, expression and activity of glucose transporters are modified to an extent that results in alterations in the maternal-fetal glucose exchange, potentially leading to an excessive supply of energy substrates to the fetus. This paper reviews the literature on the expression and activity of glucose transporter proteins-GLUT-1, GLUT-3, GLUT-4, GLUT-8, GLUT-9 and GLUT-12-in the human placenta, with a special focus on diabetes-complicated pregnancy. The characteristics of transporters in conditions of maternal normoglycemia and modifications occurring in the diabetic placenta are summarized, and the factors responsible for the regulation of the expression of selected isoforms are described. Finally, the impact of alterations in the placental expression of the aforementioned members of the GLUT family on intrauterine fetal development in pregnancies complicated by diabetes mellitus is discussed. Copyright © 2017 Diabetes Canada. Published by Elsevier Inc. All rights reserved.

Cytoskeleton-associated protein 5 and clathrin heavy chain binding regulates spindle assembly in mouse oocytes

PubMed Central

Wang, Dong-Hui; Han, Zhe; Kong, Xiang-Wei; Ma, Yu-Zhen; Yun, Zhi-Zhong; Liang, Cheng-Guang

2017-01-01

Mammalian oocyte meiotic maturation is the precondition of early embryo development. Lots of microtubules (MT)-associated proteins participate in oocyte maturation process. Cytoskeleton-associated protein 5 (CKAP5) is a member of the XMAP215 family that regulates microtubule dynamics during mitosis. However, its role in meiosis has not been fully studied. Here, we investigated the function of CKAP5 in mouse oocyte meiotic maturation and early embryo development. Western blot showed that CKAP5 expression increased from GVBD, maintaining at high level at metaphase, and decreased after late 1-cell stage. Confocal microscopy showed there is no specific accumulation of CKAP5 at interphase (GV, PN or 2-cell stage). However, once cells enter into meiotic or mitotic division, CKAP5 was localized at the whole spindle apparatus. Treatment of oocytes with the tubulin-disturbing reagents nocodazole (induces MTs depolymerization) or taxol (prevents MTs depolymerization) did not affect CKAP5 expression but led to a rearrangement of CKAP5. Further, knock-down of CKAP5 resulted in a failure of first polar body extrusion, serious defects in spindle assembly, and failure of chromosome alignment. Loss of CKAP5 also decreased early embryo development potential. Furthermore, co-immunoprecipitation showed that CKAP5 bound to clathrin heavy chain 1 (CLTC). Taken together, our results demonstrate that CKAP5 is important in oocyte maturation and early embryo development, and CKAP5 might work together with CLTC in mouse oocyte maturation. PMID:28177917

Some methodological aspects of ethics committees' expertise: the Ukrainian example.

PubMed

Pustovit, Svitlana V

2006-01-01

Today local, national and international ethics committees have become an effective means of social regulation in many European countries. Science itself is an important precondition for the development of bioethical knowledge and ethics expertise. Cultural, social, historical and religious preconditions can facilitate different forms and methods of ethics expertise in each country. Ukrainian ethics expertise has some methodological problems connected with its socio-cultural, historical, science and philosophy development particularities. In this context, clarification of some common legitimacies or methodological approaches to ethics committee (EC) phenomena such as globalization, scientization and the prioritization of an ethics paradigm are very important. On the other hand, elaborate study and critical analysis of international experience by Ukraine and other Eastern European countries will provide the integration of their local and national ethics expertises into a world bioethics ethos.

Selenium recovery from kiln powder of cement manufacturing by chemical leaching and bioreduction.

PubMed

Soda, S; Hasegawa, A; Kuroda, M; Hanada, A; Yamashita, M; Ike, M

2015-01-01

A novel process by using chemical leaching followed by bacterial reductive precipitation was proposed for selenium recovery from kiln powder as a byproduct of cement manufacturing. The kiln powder at a slurry concentration of 10 w/v% with 0.25 M Na2CO3 at 28°C produced wastewater containing about 30 mg-Se/L selenium. The wastewater was diluted four-fold and adjusted to pH 8.0 as preconditioning for bioreduction. A bacterial strain Pseudomonas stutzeri NT-I, capable of reducing selenate and selenite into insoluble elemental selenium, could recover about 90% selenium from the preconditioned wastewater containing selenium of 5 mg-Se/L when supplemented with lactate or glycerol. The selenium concentrations in the treated wastewater were low around the regulated effluent concentration of 0.1 mg-Se/L in Japan.

[The relationship between ischemic preconditioning-induced infarction size limitation and duration of test myocardial ischemia].

PubMed

Blokhin, I O; Galagudza, M M; Vlasov, T D; Nifontov, E M; Petrishchev, N N

2008-07-01

Traditionally infarction size reduction by ischemic preconditioning is estimated in duration of test ischemia. This approach limits the understanding of real antiischemic efficacy of ischemic preconditioning. Present study was performed in the in vivo rat model of regional myocardial ischemia-reperfusion and showed that protective effect afforded by ischemic preconditioning progressively decreased with prolongation of test ischemia. There were no statistically significant differences in infarction size between control and preconditioned animals when the duration of test ischemia was increased up to 1 hour. Preconditioning ensured maximal infarction-limiting effect in duration of test ischemia varying from 20 to 40 minutes.

Permanently Hypoxic Cell Culture Yields Rat Bone Marrow Mesenchymal Cells with Higher Therapeutic Potential in the Treatment of Chronic Myocardial Infarction.

PubMed

Liu, Yihua; Yang, Xiaoxi; Maureira, Pablo; Falanga, Aude; Marie, Vanessa; Gauchotte, Guillaume; Poussier, Sylvain; Groubatch, Frederique; Marie, Pierre-Yves; Tran, Nguyen

2017-01-01

The mismatch between traditional in vitro cell culture conditions and targeted chronic hypoxic myocardial tissue could potentially hamper the therapeutic effects of implanted bone marrow mesenchymal stem cells (BMSCs). This study sought to address (i) the extent of change to BMSC biological characteristics in different in vitro culture conditions and (ii) the effectiveness of permanent hypoxic culture for cell therapy in treating chronic myocardial infarction (MI) in rats. rat BMSCs were harvested and cultured in normoxic (21% O2, n=27) or hypoxic conditions (5% O2, n=27) until Passage 4 (P4). Cell growth tests, flow cytometry, and Bio-Plex assays were conducted to explore variations in the cell proliferation, phenotype, and cytokine expression, respectively. In the in vivo set-up, P3-BMSCs cultured in normoxia (n=6) or hypoxia (n=6) were intramyocardially injected into rat hearts that had previously experienced 1-month-old MI. The impact of cell therapy on cardiac segmental viability and hemodynamic performance was assessed 1 month later by 2-Deoxy-2[18F]fluoro-D-glucose (18F-FDG) positron emission tomography (PET) imaging and pressure-volume catheter, respectively. Additional histomorphological examinations were conducted to evaluate inflammation, fibrosis, and neovascularization. Hypoxic preconditioning significantly enhanced rat BMSC clonogenic potential and proliferation without altering the multipotency. Different profiles of inflammatory, fibrotic, and angiogenic cytokine secretion were also documented, with a marked correlation observed between in vitro and in vivo proangiogenic cytokine expression and tissue neovessels. Hypoxic-preconditioned cells presented a beneficial effect on the myocardial viability of infarct segments and intrinsic contractility. Hypoxic-preconditioned BMSCs were able to benefit myocardial perfusion and contractility, probably by modulating the inflammation and promoting angiogenesis. © 2017 The Author(s). Published by S. Karger AG, Basel.

Preconditioning of mesenchymal stromal cells toward nucleus pulposus-like cells by microcryogels-based 3D cell culture and syringe-based pressure loading system.

PubMed

Zeng, Yang; Feng, Siyu; Liu, Wei; Fu, Qinyouen; Li, Yaqian; Li, Xiaokang; Chen, Chun; Huang, Chenyu; Ge, Zigang; Du, Yanan

2017-04-01

To precondition mesenchymal stromal/stem cells (MSCs) with mechanical stimulation may enhance cell survival and functions following implantation in load bearing environment such as nucleus pulposus (NP) in intervertebral disc (IVD). In this study, preconditioning of MSCs toward NP-like cells was achieved in previously developed poly (ethylene glycol) diacrylate (PEGDA) microcryogels (PMs) within a syringe-based three-dimensional (3D) culture system which provided a facile and cost-effective pressure loading approach. PMs loaded with alginate and MSCs could be incubated in a sealable syringe which could be air-compressed to apply pressure loading through a programmable syringe pump. Expression levels of chondrogenic marker genes SOX9, COL II, and ACAN were significantly upregulated in MSCs when pressure loading of 0.2 MPa or 0.8 MPa was implemented. Expression levels of COL I and COL X were downregulated when pressure loading was applied. In a nude mouse model, MSCs loaded in PMs mechanically stimulated for three days were subcutaneously injected using the same culture syringe. Three weeks postinjection, more proteoglycans (PGs) were deposited and more SOX9 and COL II but less COL I and COL X were stained in 0.2 MPa group. Furthermore, injectable MSCs-loaded PMs were utilized in an ex vivo rabbit IVD organ culture model that demonstrated the leak-proof function and enhanced cell retention of PMs assisted cell delivery to a load bearing environment for potential NP regeneration. This microcryogels-based 3D cell culture and syringe-based pressure loading system represents a novel method for 3D cell culture with mechanical stimulation for better function. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 507-520, 2017. © 2015 Wiley Periodicals, Inc.

Effect of heat shock preconditioning on ROS scavenging activity in rat skeletal muscle after downhill running.

PubMed

Shima, Yosuke; Kitaoka, Katsuhiko; Yoshiki, Yumiko; Maruhashi, Yoshinobu; Tsuyama, Takeshi; Tomita, Katsuro

2008-10-01

The mechanisms of the protective effect conferred by heat shock preconditioning (HS) are currently unknown. The purpose of this study was to determine the effect of HS on muscle injury after downhill running and to address the mechanism of the effect. Female Wistar rats were assigned to three groups: HS, downhill running (E), and downhill running after heat shock preconditioning (HS + E). The HS and HS + E rats were placed in a heat chamber for 60 min (ambient temperature 42 +/- 1.0 degrees C) 48 h before downhill running. Reactive oxygen species (ROS) scavenging activity was determined by electron spin resonance (ESR), and heat shock protein 72 (HSP72) mRNA expression was measured in rat quadriceps femoris. Leukocyte infiltration and degenerated muscle fibers were determined histopathologically. ROS scavenging activity significantly increased at 3 days after HS (151 +/- 18%) and HSP72 mRNA expression increased immediately after HS (1750 +/- 1914%). No decrease in ROS scavenging activity was observed in the HS + E rats at 2 days after exercise compared with the E rats (102 +/- 9% vs. 79 +/- 5%). Degenerated muscle fibers in HS + E rats were significantly less than in E rats at 2, 3, and 7 days after exercise (0.8 +/- 1.0 vs. 2.8 +/- 1.6, 0.8 +/- 1.0 vs. 1.8 +/- 1.6, 0 vs. 0.3 +/- 0.6, respectively). These data demonstrated that HS can reduce muscle injury after downhill running, and this effect may be mediated by increased ROS scavenging activity. Furthermore, HS may protect the antioxidant defense system in skeletal muscle by enhancing the adaptive HSP72 mRNA response.

Research on the Changes to the Lipid/Polymer Membrane Used in the Acidic Bitterness Sensor Caused by Preconditioning

PubMed Central

Harada, Yuhei; Noda, Junpei; Yatabe, Rui; Ikezaki, Hidekazu; Toko, Kiyoshi

2016-01-01

A taste sensor that uses lipid/polymer membranes can evaluate aftertastes felt by humans using Change in membrane Potential caused by Adsorption (CPA) measurements. The sensor membrane for evaluating bitterness, which is caused by acidic bitter substances such as iso-alpha acid contained in beer, needs an immersion process in monosodium glutamate (MSG) solution, called “MSG preconditioning”. However, what happens to the lipid/polymer membrane during MSG preconditioning is not clear. Therefore, we carried out three experiments to investigate the changes in the lipid/polymer membrane caused by the MSG preconditioning, i.e., measurements of the taste sensor, measurements of the amount of the bitterness substance adsorbed onto the membrane and measurements of the contact angle of the membrane surface. The CPA values increased as the preconditioning process progressed, and became stable after 3 d of preconditioning. The response potentials to the reference solution showed the same tendency of the CPA value change during the preconditioning period. The contact angle of the lipid/polymer membrane surface decreased after 7 d of MSG preconditioning; in short, the surface of the lipid/polymer membrane became hydrophilic during MSG preconditioning. The amount of adsorbed iso-alpha acid was increased until 5 d preconditioning, and then it decreased. In this study, we revealed that the CPA values increased with the progress of MSG preconditioning in spite of the decrease of the amount of iso-alpha acid adsorbed onto the lipid/polymer membrane, and it was indicated that the CPA values increase because the sensor sensitivity was improved by the MSG preconditioning. PMID:26891299

Cortical spreading depression preconditioning mediates neuroprotection against ischemic stroke by inducing AMP-activated protein kinase-dependent autophagy in a rat cerebral ischemic/reperfusion injury model.

PubMed

Shen, Pingping; Hou, Shuai; Zhu, Mingqin; Zhao, Mingming; Ouyang, Yibing; Feng, Jiachun

2017-03-01

Cortical spreading depression (CSD), based on its similarities with peri-infarct depolarization, is an ideal model for investigating transformation from the ischemic penumbra to infarct core. However, the underlying mechanisms remain unclear. To our knowledge, this is the first study to use a middle cerebral artery occlusion ischemic-reperfusion (I/R) injury model to determine whether AMP-activated protein kinase (AMPK)-dependent autophagy contributes to the neuroprotection of CSD preconditioning in rat cortex. In this study, we topically applied a pledget soaked in 1 mol/L KCl solution on rat cortex for 2 h to elicite CSD or 1 mol/L NaCl solution as a control. The results demonstrated that CSD preconditioning significantly decreased the infarct volume, neurological deficits and neuronal apoptosis in the cortical penumbra of middle cerebral artery occlusion rats, which was inhibited by the autophagy inhibitor 3-methyladenine (3-MA, 200 nmol). Furthermore, CSD increased the protein levels of the autophagy markers LC3-II, Beclin-1 and the p-AMPK (Thr 172 )/AMPK ratio at 12 h and decreased P62 and p-P70S6K (Thr 389 ). Moreover, the AMPK inhibitor Compound C (20 mg/kg) down-regulated the LC3-II, p-AMPK (Thr 172 )/AMPK and ULK1 levels, up-regulated the P62 and p-P70S6K (Thr 389 ) levels induced by CSD. The neuroprotection of CSD is likely a result of AMPK-mediated autophagy activity and autophagy-induced neuronal cells apoptosis inhibition. These novel findings support a central role for AMPK and autophagy in CSD-induced ischemic tolerance. AMPK-mediated autophagy may represent a new target for stroke. © 2016 International Society for Neurochemistry.

Electroacupuncture preconditioning-induced neuroprotection may be mediated by glutamate transporter type 2

PubMed Central

Zhu, Xiaoling; Yin, Jinbo; Li, Liaoliao; Ma, Lei; Tan, Hongying; Deng, Jiao; Chen, Shaoyang; Zuo, Zhiyi

2013-01-01

Electroacupuncture has been shown to induce a preconditioning effect in the brain. The mechanisms for this protection are not fully elucidated. We hypothesize that this protection is mediated by excitatory amino acid transporters (EAATs) that have been shown to be neuroprotective. To test this hypothesis, two-month old male Sprague-Dawley rats and EAAT type 3 (EAAT3) knockout mice received or did not receive 30-min electroacupuncture once a day for 5 consecutive days. They were subjected to a 120-min middle cerebral arterial occlusion (MCAO) at 24 h after the last electroacupuncture. Neurological outcome was assessed 2 days after the MCAO. Brain tissues were harvested at 24 h after the last electroacupuncture for Western blotting. Rats subjected to electroacupuncture at the Baihui acupoint had smaller brain infarct volumes and better neurological deficit scores than control rats. Electroacupuncture increased EAAT type 2 (EAAT2) in the cerebral cortex, tended to increase EAAT3 in the hippocampus, and had no effect on EAAT type 1 expression. Dihydrokainate, an EAAT2 inhibitor, worsened the neurological outcome of rats with electroacupuncture pretreatment. Electroacupuncture pretreatment at the Baihui acupoint increased EAAT2 in the cerebral cortex and improved the neurological outcome of EAAT3 knockout mice. Together, our results suggest that EAAT2 may mediate the electroacupuncture preconditioning-induced neuroprotection. PMID:23831620

Bioengineering Silicon Quantum Dot Theranostics using a Network Analysis of Metabolomic and Proteomic Data in Cardiac Ischemia

PubMed Central

Erogbogbo, Folarin; May, Jasmine; Swihart, Mark; Prasad, Paras N.; Smart, Katie; Jack, Seif El; Korcyk, Dariusz; Webster, Mark; Stewart, Ralph; Zeng, Irene; Jullig, Mia; Bakeev, Katherine; Jamieson, Michelle; Kasabov, Nikolas; Gopalan, Banu; Liang, Linda; Hu, Raphael; Schliebs, Stefan; Villas-Boas, Silas; Gladding, Patrick

2013-01-01

Metabolomic profiling is ideally suited for the analysis of cardiac metabolism in healthy and diseased states. Here, we show that systematic discovery of biomarkers of ischemic preconditioning using metabolomics can be translated to potential nanotheranostics. Thirty-three patients underwent percutaneous coronary intervention (PCI) after myocardial infarction. Blood was sampled from catheters in the coronary sinus, aorta and femoral vein before coronary occlusion and 20 minutes after one minute of coronary occlusion. Plasma was analysed using GC-MS metabolomics and iTRAQ LC-MS/MS proteomics. Proteins and metabolites were mapped into the Metacore network database (GeneGo, MI, USA) to establish functional relevance. Expression of 13 proteins was significantly different (p<0.05) as a result of PCI. Included amongst these was CD44, a cell surface marker of reperfusion injury. Thirty-eight metabolites were identified using a targeted approach. Using PCA, 42% of their variance was accounted for by 21 metabolites. Multiple metabolic pathways and potential biomarkers of cardiac ischemia, reperfusion and preconditioning were identified. CD44, a marker of reperfusion injury, and myristic acid, a potential preconditioning agent, were incorporated into a nanotheranostic that may be useful for cardiovascular applications. Integrating biomarker discovery techniques into rationally designed nanoconstructs may lead to improvements in disease-specific diagnosis and treatment. PMID:24019856

[Quality assurance in interventional cardiology].

PubMed

Gülker, H

2009-10-01

Quality assurance in clinical studies aiming at approval of pharmaceutical products is submitted to strict rules, controls and auditing regulations. Comparative instruments to ensure quality in diagnostic and therapeutic procedures are not available in interventional cardiology, likewise in other fields of cardiovascular medicine. Quality assurance simply consists of "quality registers" with basic data not externally controlled. Based on the experiences of clinical studies and their long history of standardization it is assumed that these data may be severely flawed thus being inappropriate to set standards for diagnostic and therapeutic strategies. The precondition for quality assurance are quality data. In invasive coronary angiography and intervention medical indications, the decision making process interventional versus surgical revascularization, technical performance and after - care are essential aspects affecting quality of diagnostics and therapy. Quality data are externally controlled data. To collect quality data an appropriate infrastructure is a necessary precondition which is not existent. For an appropriate infrastructure investments have to be done both to build up as well as to sustain the necessary preconditions. As long as there are no infrastructure and no investments there will be no "quality data". There exist simply registers of data which are not proved to be a basis for significant assurance and enhancement in quality in interventional coronary cardiology. Georg Thieme Verlag KG Stuttgart, New York.

Parallel Preconditioning for CFD Problems on the CM-5

NASA Technical Reports Server (NTRS)

Simon, Horst D.; Kremenetsky, Mark D.; Richardson, John; Lasinski, T. A. (Technical Monitor)

1994-01-01

Up to today, preconditioning methods on massively parallel systems have faced a major difficulty. The most successful preconditioning methods in terms of accelerating the convergence of the iterative solver such as incomplete LU factorizations are notoriously difficult to implement on parallel machines for two reasons: (1) the actual computation of the preconditioner is not very floating-point intensive, but requires a large amount of unstructured communication, and (2) the application of the preconditioning matrix in the iteration phase (i.e. triangular solves) are difficult to parallelize because of the recursive nature of the computation. Here we present a new approach to preconditioning for very large, sparse, unsymmetric, linear systems, which avoids both difficulties. We explicitly compute an approximate inverse to our original matrix. This new preconditioning matrix can be applied most efficiently for iterative methods on massively parallel machines, since the preconditioning phase involves only a matrix-vector multiplication, with possibly a dense matrix. Furthermore the actual computation of the preconditioning matrix has natural parallelism. For a problem of size n, the preconditioning matrix can be computed by solving n independent small least squares problems. The algorithm and its implementation on the Connection Machine CM-5 are discussed in detail and supported by extensive timings obtained from real problem data.

[Effect of Moxibustion Preconditioning with Seed-sized Moxa Cones on Myocardial Infarction Size and Beclin 1 Expression in Myocardial Ischemia-reperfusion Injury Rats].

PubMed

Bai, Hua; Lu, Sheng-Feng; Chen, Wan-Ying; Zhong, Ze-Hao; Gu, Yi-Huang

2017-12-25

To observe the effect of moxibustion (Moxi) preconditioning with seed-sized moxa cones on myocardial ischemia-reperfusion injury (MI/RI) at different stages, and to analyze the correlation between this effect and the expression of autophagy related protein Beclin 1. This study contains two parts: 1) changes of myocardial pathological injury and percentages of myocardial infarcted area at different time-points after modeling and Moxi intervention, and 2) effect of Moxi on contents of serum cardiac troponin T(cTnT) and expression of myocardial Bcl-2, Bax and Beclin 1 proteins. In the first part, 42 SD rats were randomly divided into model group, 1 day (d) Moxi group, 2 d Moxi group, 3 d Moxi group，4 d Moxi group, 5 d Moxi group and 7 d Moxi group. The model of MI/RI was established by ligating the left anterior descending coronary artery (LAD) for 30 min and reperfusion for 240 min. The electrocardiogram (ECG) of standard limb lead Ⅱ was monitored and the heart was taken 4 h after reperfusion for examining myocardial infarcted size with triphenyl tetrazolium chloride (TTC) staining. In the second part, 48 SD rats were randomized into sham-operation, model, moxibustion and autophagy inhibitor (3-MA) groups, with 12 rats in each group. The serum cTnT level was assayed and histopathological changes of the myocardial tissue below the ligation site were examined with HE staining, and the expression levels of Bcl-2, Bax and Beclin 1 proteins in the myocardial tissue below the LAD-ligated site were detected using Western blot. Compared with the model group, the percentages of myocardial infarcted area were significantly decreased in the 4 d, 5 d and 7 d Moxi groups ( P <0.05), but without significant differences among the 3 Moxi groups ( P >0.05). The state of MI-induced breakage and disordered arrangement of myocardial fibers with interstitial edema and inflammatory cell infiltration at the MI stage in the Moxi group and at the reperfusion stage in the autophagy inhibitor group was relatively lighter. The levels of serum cTnT content and Bax/Bcl-2 and Beclin 1 protein expression at the MI and reperfusion stages were significantly higher in the model group than in the sham-operation group ( P <0.01), and considerably lower in the Moxi and autophagy groups than in the model group ( P <0.01). The serum cTnT content, ratio of Bax/Bcl-2 expression and Beclin 1 expression levels at the MI and reperfusion stages were significantly lower in the autophagy inhibitor group than in the Moxi group ( P <0.05). Moxibustion with seed-sized moxa cones at "Neiguan" (PC 6) can effectively alleviate myocardial ischemia in MI/RI rats, which is probably related to its effect in down-regulating Bax/Bcl-2 and Beclin 1 expression and in inhibiting autophagy.

The chloroplast division mutant caa33 of Arabidopsis thaliana reveals a crucial impact of chloroplast homeostasis on stress acclimation and retrograde plastid-to-nucleus signaling

PubMed Central

Šimková, Klára; Kim, Chanhong; Gacek, Katarzyna; Baruah, Aiswarya; Laloi, Christophe; Apel, Klaus

2011-01-01

SUMMARY Retrograde plastid-to-nucleus signaling tightly controls and coordinates nuclear and plastid gene expression that is required for plastid biogenesis and chloroplast activities. As chloroplasts act as sensors of environmental changes, plastid-derived signaling also modulates stress responses of plants by transferring stress-related signals and altering nuclear gene expression. Various mutant screens have been undertaken to identify constituents of plastid signaling pathways. Almost all mutations identified in these screens have in common that they target plastid-specific but not extra-plastidic functions. They have been suggested to define either genuine constituents of retrograde signaling pathways or components required for the synthesis of plastid signals. Here we report the characterization of the caa33 (constitutive activator of AAA-ATPase) mutant, which reveals another way of how mutations that affect plastid functions may modulate retrograde plastid signaling. caa33 disturbs a plastid-specific function by impeding plastid division thereby perturbing plastid homeostasis. This results in pre-conditioning plants by activating the expression of stress genes, enhancing pathogen resistance and attenuating the plant’s capacity to respond to plastid signals. Our study reveals an intimate link between chloroplast activity and the plant’s susceptibility to stress and emphasizes the need to consider the possible impact of pre-conditioning on retrograde plastid-to-nucleus signaling. PMID:22014227

Role of calcitonin gene-related peptide in cardioprotection of short-term and long-term exercise preconditioning.

PubMed

Sun, Xiao-Juan; Pan, Shan-Shan

2014-07-01

To examine the role of calcitonin gene-related peptide (CGRP) in cardioprotection of short-term and long-term exercise preconditioning (EP). Male Sprague-Dawley rats were, respectively, subjected to continuous intermittent treadmill training 3 days or 3 weeks as short-term or long-term EP protocols. The myocardial injury induced by isoproterenol (ISO) was performed 24 hours after short-term and long-term EP. The myocardial injury was evaluated in terms of the serum cardiac troponin levels and the hematoxylin-basic fuchsin-picric acid staining. Additionally, serum CGRP levels, CGRP expression in the dorsal root ganglion (DRG), and heart were analyzed as possible mechanisms to explain short-term and long-term EP-induced cardioprotection. Both short-term and long-term EP markedly attenuated the isoproterenol-induced myocardial ischemia with lower serum cardiac troponin levels. Short-term EP does not alter serum CGRP levels and CGRP expression in the DRG and heart. Long-term EP significantly increases serum CGRP levels and CGRP expression in the DRG and heart. The results indicate that short-term EP does not increase the synthesis and release of CGRP. Therefore, the cardioprotective effect of short-term EP does not involve CGRP adaptation. Furthermore, long-term EP increases CGRP synthesis in the DRG and promotes CGRP release in the blood and heart. Hence, CGRP may play an important role in the cardioprotective effect of long-term EP.

MicroRNA-218 promotes high glucose-induced apoptosis in podocytes by targeting heme oxygenase-1.

PubMed

Yang, Haibo; Wang, Qingjun; Li, Sutong

2016-03-18

Emerging evidence has demonstrated that microRNAs (miRNAs) play a mediatory role in the pathogenesis of diabetic nephropathy. In this study, we found that miR-218 was upregulated in high glucose (HG) treated podocytes, which are essential components of the glomerular filtration barrier and a major prognostic determinant in diabetic nephropathy. Additionally, up-regulation of miR-218 was accompanied by an increased rate of podocyte death and down-regulation in the level of nephrin, a key marker of podocytes. However, inhibition of miR-218 exerted the opposite effect. In addition, the dual-luciferase reporter assay showed that miR-218 directly targeted the 3'-untranslated region of heme oxygenase-1 (HO-1), and further study confirmed an increase of HO-1 in HG-treated podocytes transfected with anti-miR-218. Knockdown of HO-1 blocked the anti-apoptotic effect of anti-miR-218. Furthermore, inhibition of miR-218 was associated with decreased expression of the known pro-apoptotic molecule p38-mitogen-activated protein kinase (p38-MAPK) activation. Following preconditioning with SB203580, an inhibitor of p38-MAPK, the stimulatory effect of HG on podocyte apoptosis was strikingly ameliorated. These findings suggested that miR-218 accelerated HG-induced podocyte apoptosis through directly down-regulating HO-1 and facilitating p38-MAPK activation. Copyright © 2016 Elsevier Inc. All rights reserved.

AdVEGF-All6A+ Preconditioning of Murine Ischemic Skin Flaps Is Comparable to Surgical Delay.

PubMed

Gersch, Robert P; Fourman, Mitchell S; Phillips, Brett T; Nasser, Ahmed; McClain, Steve A; Khan, Sami U; Dagum, Alexander B; Bui, Duc T

2015-08-01

Surgical flap delay is commonly used in preconditioning reconstructive flaps to prevent necrosis. However, staged procedures are not ideal. Pharmacologic up-regulation of angiogenic and arteriogenic factors before flap elevation poses a nonsurgical approach to improve flap survival. Male Sprague Dawley rats were divided into control (n = 16), surgical delay (Delay), AdNull, AdEgr-1, and AdVEGF (n ≥ 9/group) groups. Delay rats had a 9 cm × 3 cm cranial based pedicle skin flap incised 10 days prior to elevation. Adenoviral groups received 28 intradermal injections (10(9) pu/animal total) throughout the distal two thirds of the flap 1 week prior to elevation. At postoperative day (POD) 0 flaps were elevated and silicone sheeting was placed between flap and wound bed. Perfusion analysis in arbitrary perfusion units of the ischemic middle third of the flap using laser Doppler imaging was conducted preoperatively and on POD 0, 3, and 7. Clinical and histopathologic assessments of the skin flaps were performed on POD 7. AdVEGF (50.8 ± 10.9 APU) and AdEgr-1 (39.3 ± 10.6 APU) perfusion levels were significantly higher than controls (16.5 ± 4.2 APU) on POD 7. Delay models were equivalent to controls (25.9 ± 6.8 APU). AdVEGF and Delay animals showed significantly more viable surface area on POD 7 (14.4 ± 1.3 cm(2), P < 0.01 and 12.4 ± 1.2 cm(2), P < 0.05, respectively) compared with Controls (8.7 ± 0.7 cm(2)). AdVEGF preconditioning resulted in flap survival comparable to surgical delay. Adenoviral preconditioning maintained perfusion levels postoperatively while surgical delay did not.

AdVEGF-All6A+ Preconditioning of Murine Ischemic Skin Flaps Is Comparable to Surgical Delay

PubMed Central

Gersch, Robert P.; Fourman, Mitchell S.; Phillips, Brett T.; Nasser, Ahmed; McClain, Steve A.; Khan, Sami U.; Dagum, Alexander B.

2015-01-01

Background: Surgical flap delay is commonly used in preconditioning reconstructive flaps to prevent necrosis. However, staged procedures are not ideal. Pharmacologic up-regulation of angiogenic and arteriogenic factors before flap elevation poses a nonsurgical approach to improve flap survival. Methods: Male Sprague Dawley rats were divided into control (n = 16), surgical delay (Delay), AdNull, AdEgr-1, and AdVEGF (n ≥ 9/group) groups. Delay rats had a 9 cm × 3 cm cranial based pedicle skin flap incised 10 days prior to elevation. Adenoviral groups received 28 intradermal injections (109 pu/animal total) throughout the distal two thirds of the flap 1 week prior to elevation. At postoperative day (POD) 0 flaps were elevated and silicone sheeting was placed between flap and wound bed. Perfusion analysis in arbitrary perfusion units of the ischemic middle third of the flap using laser Doppler imaging was conducted preoperatively and on POD 0, 3, and 7. Clinical and histopathologic assessments of the skin flaps were performed on POD 7. Results: AdVEGF (50.8 ± 10.9 APU) and AdEgr-1 (39.3 ± 10.6 APU) perfusion levels were significantly higher than controls (16.5 ± 4.2 APU) on POD 7. Delay models were equivalent to controls (25.9 ± 6.8 APU). AdVEGF and Delay animals showed significantly more viable surface area on POD 7 (14.4 ± 1.3 cm2, P < 0.01 and 12.4 ± 1.2 cm2, P < 0.05, respectively) compared with Controls (8.7 ± 0.7 cm2). Conclusions: AdVEGF preconditioning resulted in flap survival comparable to surgical delay. Adenoviral preconditioning maintained perfusion levels postoperatively while surgical delay did not. PMID:26495207

Effect of hyperbaric oxygen preconditioning on peri-hemorrhagic focal edema and aquaporin-4 expression.

PubMed

Fang, Jinyong; Li, Hongling; Li, Guanglei; Wang, Lichun

2015-08-01

The aim of the present study was to investigate the effect of hyperbaric oxygen preconditioning (HBO-PC) on peri-hemorrhagic focal edema and aquaporin-4 (AQP-4) expression in an experimental intracerebral hemorrhage (ICH) rat model. Sixty-six Sprague Dawley® rats were divided into three groups: The sham-surgery group (SHG; n=6); the control group (A-ICH; n=30), in which the rats were injected with autologous blood; and the experimental HBO-PC group (P-HBO; n=30). The rats underwent brain edema and AQP-4 detection at 5 postoperative time-points (24, 48 and 72 h and 5 and 7 days). The water content in the brain tissues of the A-ICH animals was higher than that in the brain tissues of the SHG rats at each time-point (P<0.05), and the edema in the P-HBO was significantly more severe 24 and 48 h postoperatively than that at 7 days postoperatively (P<0.05). The difference between the P-HBO and A-ICH was significant at 48 and 72 h postoperatively (P<0.05). AQP-4 was expressed in the post-hemorrhagic rat brains of all groups; the SHG animals exhibited low expression, while the A-ICH animals exhibited an increased expression 24 h postoperatively. In the A-ICH, expression peaked at 48 h postoperatively and began to decrease gradually after 72 h. At the 7-day time-point, the expression level in the A-ICH was closer to but still higher than that of the SHG animals (P<0.05). The differences between the P-HBO and A-ICH animals at the postoperative 24-h, 48-h and 7-day time-points were statistically significant (P<0.05). In conclusion, HBO-PC may downregulate AQP-4 expression to reduce the intracerebral edema, thus strengthening tolerance to ICH and protecting the nerves.

Morphine-Induced Preconditioning: Involvement of Protein Kinase A and Mitochondrial Permeability Transition Pore

PubMed Central

Dorsch, Marianne; Behmenburg, Friederike; Raible, Miriam; Blase, Dominic; Grievink, Hilbert; Hollmann, Markus W.; Heinen, André; Huhn, Ragnar

2016-01-01

Background Morphine induces myocardial preconditioning (M-PC) via activation of mitochondrial large conductance Ca2+-sensitive potassium (mKCa) channels. An upstream regulator of mKCa channels is protein kinase A (PKA). Furthermore, mKCa channel activation regulates mitochondrial bioenergetics and thereby prevents opening of the mitochondrial permeability transition pore (mPTP). Here, we investigated in the rat heart in vivo whether 1) M-PC is mediated by activation of PKA, and 2) pharmacological opening of the mPTP abolishes the cardioprotective effect of M-PC and 3) M-PC is critically dependent on STAT3 activation, which is located upstream of mPTP within the signalling pathway. Methods Male Wistar rats were randomised to six groups (each n = 6). All animals underwent 25 minutes of regional myocardial ischemia and 120 minutes of reperfusion. Control animals (Con) were not further treated. Morphine preconditioning was initiated by intravenous administration of 0.3 mg/kg morphine (M-PC). The PKA blocker H-89 (10 μg/kg) was investigated with and without morphine (H-89+M-PC, H-89). We determined the effect of mPTP opening with atractyloside (5 mg/kg) with and without morphine (Atr+M-PC, Atr). Furthermore, the effect of morphine on PKA activity was tested in isolated adult rat cardiomyocytes. In further experiments in isolated hearts we tested the protective properties of morphine in the presence of STAT3 inhibition, and whether pharmacological prevention of the mPTP-opening by cyclosporine A (CsA) is cardioprotective in the presence of STAT3 inhibition. Results Morphine reduced infarct size from 64±5% to 39±9% (P<0.05 vs. Con). H-89 completely blocked preconditioning by morphine (64±9%; P<0.05 vs. M-PC), but H-89 itself had not effect on infarct size (61±10%; P>0.05 vs. Con). Also, atractyloside abolished infarct size reduction of morphine completely (65±9%; P<0.05 vs. M-PC) but had no influence on infarct size itself (64±5%; P>0.05 vs. Con). In isolated hearts STAT3 inhibitor Stattic completely abolished morphine-induced preconditioning. Administration of Stattic and mPTP inhibitor cyclosporine A reduced infarct size to 31±6% (Stat+CsA, P<0.05 vs. Con). Cyclosporine A alone reduced infarct size to 26±7% (CsA P<0.05 vs. Con). In cardiomyocytes, PKA activity was increased by morphine. Conclusion Our data suggest that morphine-induced cardioprotection is mediated by STAT3-activation and inhibition of mPTP, with STA3 located upstream of mPTP. There is some evidence that protein kinase A is involved within the signalling pathway. PMID:26968004

The in vitro preconditioning of myoblasts to enhance subsequent survival in an in vivo tissue engineering chamber model.

PubMed

Tilkorn, Daniel J; Davies, E Michele; Keramidaris, Effie; Dingle, Aaron M; Gerrand, Yi-Wen; Taylor, Caroline J; Han, Xiao Lian; Palmer, Jason A; Penington, Anthony J; Mitchell, Christina A; Morrison, Wayne A; Dusting, Gregory J; Mitchell, Geraldine M

2012-05-01

The effects of in vitro preconditioning protocols on the ultimate survival of myoblasts implanted in an in vivo tissue engineering chamber were examined. In vitro testing: L6 myoblasts were preconditioned by heat (42 °C; 1.5 h); hypoxia (<8% O(2); 1.5 h); or nitric oxide donors: S-nitroso-N-acetylpenicillamine (SNAP, 200 μM, 1.5 h) or 1-[N-(2-aminoethyl)-N-(2-aminoethyl)amino]-diazen-1-ium-1,2-diolate (DETA-NONOate, 500 μM, 7 h). Following a rest phase preconditioned cells were exposed to 24 h hypoxia, and demonstrated minimal overall cell loss, whilst controls (not preconditioned, but exposed to 24 h hypoxia) demonstrated a 44% cell loss. Phosphoimmunoblot analysis of pro-survival signaling pathways revealed significant activation of serine threonine kinase Akt with DETA-NONOate (p < 0.01) and heat preconditioning (p < 0.05). DETA-NONOate also activated ERK 1/2 signaling (p < 0.05). In vivo implantation: 100,000 preconditioned (heat, hypoxia, or DETA-NONOate) myoblasts were implanted in SCID mouse tissue engineering chambers. 100,000 (not preconditioned) myoblasts were implanted in control chambers. At 3 weeks, morphometric assessment of surviving myoblasts indicated myoblast percent volume (p = 0.012) and myoblasts/mm(2) (p = 0.0005) overall significantly increased in preconditioned myoblast chambers compared to control, with DETA-NONOate-preconditioned myoblasts demonstrating the greatest increase in survival (p = 0.007 and p = 0.001 respectively). DETA-NONOate therefore has potential therapeutic benefits to significantly improve survival of transplanted cells. Copyright © 2012 Elsevier Ltd. All rights reserved.

Preconditioning Provides Neuroprotection in Models of CNS Disease: Paradigms and Clinical Significance

PubMed Central

Stetler, R. Anne; Leak, Rehana K.; Gan, Yu; Li, Peiying; Hu, Xiaoming; Jing, Zheng; Chen, Jun; Zigmond, Michael J.; Gao, Yanqin

2014-01-01

Preconditioning is a phenomenon in which brief episodes of a sublethal insult induce robust protection against subsequent lethal injuries. Preconditioning has been observed in multiple organisms and can occur in the brain as well as other tissues. Extensive animal studies suggest that the brain can be preconditioned to resist acute injuries, such as ischemic stroke, neonatal hypoxia/ischemia, trauma, and agents that are used in models of neurodegenerative diseases, such as Parkinson’s disease and Alzheimer’s disease. Effective preconditioning stimuli are numerous and diverse, ranging from transient ischemia, hypoxia, hyperbaric oxygen, hypothermia and hyperthermia, to exposure to neurotoxins and pharmacological agents. The phenomenon of “cross-tolerance,” in which a sublethal stress protects against a different type of injury, suggests that different preconditioning stimuli may confer protection against a wide range of injuries. Research conducted over the past few decades indicates that brain preconditioning is complex, involving multiple effectors such as metabolic inhibition, activation of extra- and intracellular defense mechanisms, a shift in the neuronal excitatory/inhibitory balance, and reduction in inflammatory sequelae. An improved understanding of brain preconditioning should help us identify innovative therapeutic strategies that prevent or at least reduce neuronal damage in susceptible patients. In this review, we focus on the experimental evidence of preconditioning in the brain and systematically survey the models used to develop paradigms for neuroprotection, and then discuss the clinical potential of brain preconditioning. In a subsequent components of this two-part series, we will discuss the cellular and molecular events that are likely to underlie these phenomena. PMID:24389580

Exploring the Role of TRPV and CGRP in Adenosine Preconditioning and Remote Hind Limb Preconditioning-Induced Cardioprotection in Rats.

PubMed

Singh, Amritpal; Randhawa, Puneet Kaur; Bali, Anjana; Singh, Nirmal; Jaggi, Amteshwar Singh

2017-04-01

The cardioprotective effects of remote hind limb preconditioning (RIPC) are well known, but mechanisms by which protection occurs still remain to be explored. Therefore, the present study was designed to investigate the role of TRPV and CGRP in adenosine and remote preconditioning-induced cardioprotection, using sumatriptan, a CGRP release inhibitor and ruthenium red, a TRPV inhibitor, in rats. For remote preconditioning, a pressure cuff was tied around the hind limb of the rat and was inflated with air up to 150 mmHg to produce ischemia in the hind limb and during reperfusion pressure was released. Four cycles of ischemia and reperfusion, each consisting of 5 min of inflation and 5 min of deflation of pressure cuff were used to produce remote limb preconditioning. An ex vivo Langendorff's isolated rat heart model was used to induce ischemia reperfusion injury by 30 min of global ischemia followed by 120 min of reperfusion. RIPC demonstrated a significant decrease in ischemia reperfusion-induced significant myocardial injury in terms of increase in LDH, CK, infarct size and decrease in LVDP, +dp/dt max and -dp/dt min . Moreover, pharmacological preconditioning with adenosine produced cardioprotective effects in a similar manner to RIPC. Pretreatment with sumatriptan, a CGRP release blocker, abolished RIPC and adenosine preconditioning-induced cardioprotective effects. Administration of ruthenium red, a TRPV inhibitor, also abolished adenosine preconditioning-induced cardioprotection. It may be proposed that the cardioprotective effects of adenosine and remote preconditioning are possibly mediated through activation of a TRPV channels and consequent, release of CGRP.

Preconditioning and the limit to the incompressible flow equations

NASA Technical Reports Server (NTRS)

Turkel, E.; Fiterman, A.; Vanleer, B.

1993-01-01

The use of preconditioning methods to accelerate the convergence to a steady state for both the incompressible and compressible fluid dynamic equations are considered. The relation between them for both the continuous problem and the finite difference approximation is also considered. The analysis relies on the inviscid equations. The preconditioning consists of a matrix multiplying the time derivatives. Hence, the steady state of the preconditioned system is the same as the steady state of the original system. For finite difference methods the preconditioning can change and improve the steady state solutions. An application to flow around an airfoil is presented.

Ischemic preconditioning protects against gap junctional uncoupling in cardiac myofibroblasts.

PubMed

Sundset, Rune; Cooper, Marie; Mikalsen, Svein-Ole; Ytrehus, Kirsti

2004-01-01

Ischemic preconditioning increases the heart's tolerance to a subsequent longer ischemic period. The purpose of this study was to investigate the role of gap junction communication in simulated preconditioning in cultured neonatal rat cardiac myofibroblasts. Gap junctional intercellular communication was assessed by Lucifer yellow dye transfer. Preconditioning preserved intercellular coupling after prolonged ischemia. An initial reduction in coupling in response to the preconditioning stimulus was also observed. This may protect neighboring cells from damaging substances produced during subsequent regional ischemia in vivo, and may preserve gap junctional communication required for enhanced functional recovery during subsequent reperfusion.

Key cognitive preconditions for the evolution of language.

PubMed

Donald, Merlin

2017-02-01

Languages are socially constructed systems of expression, generated interactively in social networks, which can be assimilated by the individual brain as it develops. Languages co-evolved with culture, reflecting the changing complexity of human culture as it acquired the properties of a distributed cognitive system. Two key preconditions set the stage for the evolution of such cultures: a very general ability to rehearse and refine skills (evident early in hominin evolution in toolmaking), and the emergence of material culture as an external (to the brain) memory record that could retain and accumulate knowledge across generations. The ability to practice and rehearse skill provided immediate survival-related benefits in that it expanded the physical powers of early hominins, but the same adaptation also provided the imaginative substrate for a system of "mimetic" expression, such as found in ritual and pantomime, and in proto-words, which performed an expressive function somewhat like the home signs of deaf non-signers. The hominid brain continued to adapt to the increasing importance and complexity of culture as human interactions with material culture became more complex; above all, this entailed a gradual expansion in the integrative systems of the brain, especially those involved in the metacognitive supervision of self-performances. This supported a style of embodied mimetic imagination that improved the coordination of shared activities such as fire tending, but also in rituals and reciprocal mimetic games. The time-depth of this mimetic adaptation, and its role in both the construction and acquisition of languages, explains the importance of mimetic expression in the media, religion, and politics. Spoken language evolved out of voco-mimesis, and emerged long after the more basic abilities needed to refine skill and share intentions, probably coinciding with the common ancestor of sapient humans. Self-monitoring and self-supervised practice were necessary preconditions for lexical invention, and as these abilities evolved further, communicative skills extended to more abstract and complex aspects of the communication environments-that is, the "cognitive ecologies"-being generated by human groups. The hominin brain adapted continuously to the need to assimilate language and its many cognitive byproducts by expanding many of its higher integrative systems, a process that seems to have accelerated and peaked in the past half million years.

Reperfusion kinase phosphorylation is essential but not sufficient in the mediation of pharmacological preconditioning: Characterisation in the bi-phasic profile of early and late protection.

PubMed

Bell, Robert M; Clark, James E; Hearse, David J; Shattock, Michael J

2007-01-01

Pharmacological preconditioning (PPC) triggers early (ePPC) and delayed protection (dPPC), occurring within 1 h or after 24 h following the preconditioning stimulus, respectively, through recruitment of protein kinase signalling. Angiotensin II (ATII) is a recognised trigger of PPC, recruiting kinases and transcription factors known to be involved in both phases of protection. Our objectives were to determine whether ATII is capable of triggering dPPC and whether recruitment of pro-survival kinases, Akt and extracellular signal-regulated kinase (ERK), following the injurious ischaemic insult is essential for the mediation of PPC. In a mouse Langendorff model of ischaemia/reperfusion injury, we undertook to determine whether ATII triggers both ePPC and dPPC. Western blot analysis was used to determine kinase phosphorylation at reperfusion, and kinase inhibitors wortmannin and PD98059 were used to ascertain the significance of kinase regulation. We demonstrated that ATII triggered PPC with attenuation of infarction at 1 and 24 h (19+/-4% and 25+/-4% versus control, 35+/-4% of risk zone, p < 0.05), consistent with the ePPC and dPPC time-course. This bi-phasic protection was associated with significant post-ischaemic phosphorylation of both Akt and ERK within the first 5 min of reperfusion. Akt and ERK phosphorylation was increased following ePPC by 4.5+/-0.5 and 1.9+/-0.6 fold, respectively (p < 0.001), and dPPC by 24+/-2.0 and 2.1+/-0.1 fold, respectively (p < 0.001). Both wortmannin and PD98059 administered during reperfusion ameliorated the phosphorylation of Akt and ERK and abrogated the resistance to infarction resulting from both ePPC and dPPC (33+/-3% and 35+/-4%, respectively, versus controls 33+/-4% and 33+/-5%, p = NS). There was no evidence of augmented phosphorylation of either p38 kinase or JNK at either time point. We demonstrate that PPC results in a clearly delineated time-course of bi-phasic protection against injurious ischemic injury that is correlated with reperfusion kinase phosphorylation of both Akt and ERK. These data indicate a novel mechanism of early and particularly delayed preconditioning.

Use of the preconditioned conjugate gradient algorithm as a generic solver for mixed-model equations in animal breeding applications.

PubMed

Tsuruta, S; Misztal, I; Strandén, I

2001-05-01

Utility of the preconditioned conjugate gradient algorithm with a diagonal preconditioner for solving mixed-model equations in animal breeding applications was evaluated with 16 test problems. The problems included single- and multiple-trait analyses, with data on beef, dairy, and swine ranging from small examples to national data sets. Multiple-trait models considered low and high genetic correlations. Convergence was based on relative differences between left- and right-hand sides. The ordering of equations was fixed effects followed by random effects, with no special ordering within random effects. The preconditioned conjugate gradient program implemented with double precision converged for all models. However, when implemented in single precision, the preconditioned conjugate gradient algorithm did not converge for seven large models. The preconditioned conjugate gradient and successive overrelaxation algorithms were subsequently compared for 13 of the test problems. The preconditioned conjugate gradient algorithm was easy to implement with the iteration on data for general models. However, successive overrelaxation requires specific programming for each set of models. On average, the preconditioned conjugate gradient algorithm converged in three times fewer rounds of iteration than successive overrelaxation. With straightforward implementations, programs using the preconditioned conjugate gradient algorithm may be two or more times faster than those using successive overrelaxation. However, programs using the preconditioned conjugate gradient algorithm would use more memory than would comparable implementations using successive overrelaxation. Extensive optimization of either algorithm can influence rankings. The preconditioned conjugate gradient implemented with iteration on data, a diagonal preconditioner, and in double precision may be the algorithm of choice for solving mixed-model equations when sufficient memory is available and ease of implementation is essential.

Unique Transcriptional Profile of Sustained Ligand-Activated Preconditioning in Pre- and Post-Ischemic Myocardium

PubMed Central

Ashton, Kevin J.; Tupicoff, Amanda; Williams-Pritchard, Grant; Kiessling, Can J.; See Hoe, Louise E.; Headrick, John P.; Peart, Jason N.

2013-01-01

Background Opioidergic SLP (sustained ligand-activated preconditioning) induced by 3–5 days of opioid receptor (OR) agonism induces persistent protection against ischemia-reperfusion (I-R) injury in young and aged hearts, and is mechanistically distinct from conventional preconditioning responses. We thus applied unbiased gene-array interrogation to identify molecular effects of SLP in pre- and post-ischemic myocardium. Methodology/Principal Findings Male C57Bl/6 mice were implanted with 75 mg morphine or placebo pellets for 5 days. Resultant SLP did not modify cardiac function, and markedly reduced dysfunction and injury in perfused hearts subjected to 25 min ischemia/45 min reperfusion. Microarray analysis identified 14 up- and 86 down-regulated genes in normoxic hearts from SLP mice (≥1.3-fold change, FDR≤5%). Induced genes encoded sarcomeric/contractile proteins (Myh7, Mybpc3,Myom2,Des), natriuretic peptides (Nppa,Nppb) and stress-signaling elements (Csda,Ptgds). Highly repressed genes primarily encoded chemokines (Ccl2,Ccl4,Ccl7,Ccl9,Ccl13,Ccl3l3,Cxcl3), cytokines (Il1b,Il6,Tnf) and other proteins involved in inflammation/immunity (C3,Cd74,Cd83, Cd86,Hla-dbq1,Hla-drb1,Saa1,Selp,Serpina3), together with endoplasmic stress proteins (known: Dnajb1,Herpud1,Socs3; putative: Il6, Gadd45g,Rcan1) and transcriptional controllers (Egr2,Egr3, Fos,Hmox1,Nfkbid). Biological themes modified thus related to inflammation/immunity, together with cellular/cardiovascular movement and development. SLP also modified the transcriptional response to I-R (46 genes uniquely altered post-ischemia), which may influence later infarction/remodeling. This included up-regulated determinants of cellular resistance to oxidant (Mgst3,Gstm1,Gstm2) and other forms of stress (Xirp1,Ankrd1,Clu), and repression of stress-response genes (Hspa1a,Hspd1,Hsp90aa,Hsph1,Serpinh1) and Txnip. Conclusions Protection via SLP is associated with transcriptional repression of inflammation/immunity, up-regulation of sarcomeric elements and natriuretic peptides, and modulation of cell stress, growth and development, while conventional protective molecules are unaltered. PMID:23991079

Matrix preconditioning: a robust operation for optical linear algebra processors.

PubMed

Ghosh, A; Paparao, P

1987-07-15

Analog electrooptical processors are best suited for applications demanding high computational throughput with tolerance for inaccuracies. Matrix preconditioning is one such application. Matrix preconditioning is a preprocessing step for reducing the condition number of a matrix and is used extensively with gradient algorithms for increasing the rate of convergence and improving the accuracy of the solution. In this paper, we describe a simple parallel algorithm for matrix preconditioning, which can be implemented efficiently on a pipelined optical linear algebra processor. From the results of our numerical experiments we show that the efficacy of the preconditioning algorithm is affected very little by the errors of the optical system.

Electroacupuncture preconditioning-induced neuroprotection may be mediated by glutamate transporter type 2.

PubMed

Zhu, Xiaoling; Yin, Jinbo; Li, Liaoliao; Ma, Lei; Tan, Hongying; Deng, Jiao; Chen, Shaoyang; Zuo, Zhiyi

2013-10-01

Electroacupuncture has been shown to induce a preconditioning effect in the brain. The mechanisms for this protection are not fully elucidated. We hypothesize that this protection is mediated by excitatory amino acid transporters (EAATs) that have been shown to be neuroprotective. To test this hypothesis, two-month old male Sprague-Dawley rats and EAAT type 3 (EAAT3) knockout mice received or did not receive 30-min electroacupuncture once a day for five consecutive days. They were subjected to a 120-min middle cerebral arterial occlusion (MCAO) at 24h after the last electroacupuncture. Neurological outcome was assessed 2days after the MCAO. Brain tissues were harvested at 24h after the last electroacupuncture for Western blotting. Rats subjected to electroacupuncture at the Baihui acupoint had smaller brain infarct volumes and better neurological deficit scores than control rats. Electroacupuncture increased EAAT type 2 (EAAT2) in the cerebral cortex, tended to increase EAAT3 in the hippocampus, and had no effect on EAAT type 1 expression. Dihydrokainate, an EAAT2 inhibitor, worsened the neurological outcome of rats with electroacupuncture pretreatment. Electroacupuncture pretreatment at the Baihui acupoint increased EAAT2 in the cerebral cortex and improved the neurological outcome of EAAT3 knockout mice. Together, our results suggest that EAAT2 may mediate the electroacupuncture preconditioning-induced neuroprotection. Copyright © 2013 Elsevier Ltd. All rights reserved.

Galilean-invariant preconditioned central-moment lattice Boltzmann method without cubic velocity errors for efficient steady flow simulations

NASA Astrophysics Data System (ADS)

Hajabdollahi, Farzaneh; Premnath, Kannan N.

2018-05-01

Lattice Boltzmann (LB) models used for the computation of fluid flows represented by the Navier-Stokes (NS) equations on standard lattices can lead to non-Galilean-invariant (GI) viscous stress involving cubic velocity errors. This arises from the dependence of their third-order diagonal moments on the first-order moments for standard lattices, and strategies have recently been introduced to restore Galilean invariance without such errors using a modified collision operator involving corrections to either the relaxation times or the moment equilibria. Convergence acceleration in the simulation of steady flows can be achieved by solving the preconditioned NS equations, which contain a preconditioning parameter that can be used to tune the effective sound speed, and thereby alleviating the numerical stiffness. In the present paper, we present a GI formulation of the preconditioned cascaded central-moment LB method used to solve the preconditioned NS equations, which is free of cubic velocity errors on a standard lattice, for steady flows. A Chapman-Enskog analysis reveals the structure of the spurious non-GI defect terms and it is demonstrated that the anisotropy of the resulting viscous stress is dependent on the preconditioning parameter, in addition to the fluid velocity. It is shown that partial correction to eliminate the cubic velocity defects is achieved by scaling the cubic velocity terms in the off-diagonal third-order moment equilibria with the square of the preconditioning parameter. Furthermore, we develop additional corrections based on the extended moment equilibria involving gradient terms with coefficients dependent locally on the fluid velocity and the preconditioning parameter. Such parameter dependent corrections eliminate the remaining truncation errors arising from the degeneracy of the diagonal third-order moments and fully restore Galilean invariance without cubic defects for the preconditioned LB scheme on a standard lattice. Several conclusions are drawn from the analysis of the structure of the non-GI errors and the associated corrections, with particular emphasis on their dependence on the preconditioning parameter. The GI preconditioned central-moment LB method is validated for a number of complex flow benchmark problems and its effectiveness to achieve convergence acceleration and improvement in accuracy is demonstrated.

Proteomics/phosphoproteomics of left ventricular biopsies from patients with surgical coronary revascularization and pigs with coronary occlusion/reperfusion: remote ischemic preconditioning.

PubMed

Gedik, Nilgün; Krüger, Marcus; Thielmann, Matthias; Kottenberg, Eva; Skyschally, Andreas; Frey, Ulrich H; Cario, Elke; Peters, Jürgen; Jakob, Heinz; Heusch, Gerd; Kleinbongard, Petra

2017-08-09

Remote ischemic preconditioning (RIPC) by repeated brief cycles of limb ischemia/reperfusion reduces myocardial ischemia/reperfusion injury. In left ventricular (LV) biopsies from patients undergoing coronary artery bypass grafting (CABG), only the activation of signal transducer and activator of transcription 5 was associated with RIPC's cardioprotection. We have now used an unbiased, non-hypothesis-driven proteomics and phosphoproteomics approach to analyze LV biopsies from patients undergoing CABG and from pigs undergoing coronary occlusion/reperfusion without (sham) and with RIPC. False discovery rate-based statistics identified a higher prostaglandin reductase 2 expression at early reperfusion with RIPC than with sham in patients. In pigs, the phosphorylation of 116 proteins was different between baseline and early reperfusion with RIPC and/or with sham. The identified proteins were not identical for patients and pigs, but in-silico pathway analysis of proteins with ≥2-fold higher expression/phosphorylation at early reperfusion with RIPC in comparison to sham revealed a relation to mitochondria and cytoskeleton in both species. Apart from limitations of the proteomics analysis per se, the small cohorts, the sampling/sample processing and the number of uncharacterized/unverifiable porcine proteins may have contributed to this largely unsatisfactory result.

TLR4 preconditioning is associated with low success of OK-432 treatment for lymphatic malformations in children.

PubMed

Reismann, Marc; Ghaffarpour, Nader; Luvall, Ethel; Jirmo, Adan; Radtke, Josephine; Claesson, Gösta; Wester, Tomas

2016-05-01

We have recently shown that the relative TLR4 expression on monocytes of low responding pediatric patients after OK-432 treatment is significantly reduced after stimulation with lipopolysaccharide (LPS) compared with high responding children. The aim of this study was to perform further analysis to explain this observation. Monocytes from children with high (HR, n = 5) and low response (LR, n = 6) after previous OK-432 treatment were stimulated with LPS for 20 h and analyzed with fluorescence-activated cell sorting (mean fluorescence intensity, MFI; level of significance P ≤ 0.05). Mean MFI after LPS stimulation was comparable in both groups (HR 1142 ± 652 units, LR 839 ± 427 units, P = 0.85). Significant changes after LPS stimulation are explained by higher pre-stimulation values in the LR group compared with the HR group (950 ± 718 vs. 477 ± 341, P = 0.25) with considerable differences of the mean expression changes after LPS stimulation (HR 665 ± 683 vs. LR -111 ± 605, P = 0.08). The previously shown reduced TLR4 upregulation on monocytes after LPS stimulation in the LR group compared with the HR group can be primarily explained by TLR preconditioning. This observation implies the use of absolute values with definite thresholds.

Eigenmode Analysis of Boundary Conditions for One-Dimensional Preconditioned Euler Equations

NASA Technical Reports Server (NTRS)

Darmofal, David L.

1998-01-01

An analysis of the effect of local preconditioning on boundary conditions for the subsonic, one-dimensional Euler equations is presented. Decay rates for the eigenmodes of the initial boundary value problem are determined for different boundary conditions. Riemann invariant boundary conditions based on the unpreconditioned Euler equations are shown to be reflective with preconditioning, and, at low Mach numbers, disturbances do not decay. Other boundary conditions are investigated which are non-reflective with preconditioning and numerical results are presented confirming the analysis.

Silymarin preconditioning protected insulin resistant rats from liver ischemia-reperfusion injury: role of endogenous H2S.

PubMed

Younis, Nahla N; Shaheen, Mohamed A; Mahmoud, Mona F

2016-08-01

Hydrogen sulfide (H2S) can protect against hepatic ischemia-reperfusion injury (HIR). However, it is unknown whether it can protect against HIR in insulin resistance. This study investigated the protective effects of silymarin against HIR in a rat model of insulin resistance and the possible involvement of endogenous H2S. Insulin resistance was first established using 10% fructose in drinking water for 10 weeks. HIR was conducted in fructose-fed rats treated with saline or silymarin (100 mg/kg), 15 min before HIR (30 min ischemia, followed by 1 h reperfusion). Insulin resistance and serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), tumor necrosis factor-α (TNF-α), interleukin-10 (IL-10), total nitrites (NO2(-)), and H2S were measured. Hepatic malondialdehyde (MDA), reduced glutathione (GSH), hydroxyproline, H2S synthesizing activity, and mRNA expression of cystathionine β-synthase (CBS) or cystathionine γ-lyase (CSE) were determined. Additionally, histopathological examination involved H&E, Sirius red, and caspase-3 immunostaining. Fructose-induced insulin resistance increased serum ALT, TNF-α, H2S and H2S synthesizing activity, and hepatic MDA, hydroxyproline, and CSE mRNA and decreased NO2(-) and GSH. These changes exacerbated the HIR injury in which endogenous H2S production was auxiliary increased. Silymarin preconditioning decreased ALT, AST, MDA, NO2(-), TNF-α, and TNF-α/IL-10 ratio, increased GSH, IL-10, improved hepatic architecture, and lowered caspase-3 immunostaining. Serum H2S, its hepatic synthesizing activity, and CSE and CBS mRNA expressions were all suppressed by silymarin pretreatment. The increases in endogenous H2S exacerbate HIR injury, whereas silymarin preconditioning protected against HIR in insulin resistant rats via powerful antioxidant, anti-inflammatory, and antiapoptotic effects along with suppressing H2S production. Copyright © 2016 Elsevier Inc. All rights reserved.

Gadolinium and ruthenium red attenuate remote hind limb preconditioning-induced cardioprotection: possible role of TRP and especially TRPV channels.

PubMed

Randhawa, Puneet Kaur; Jaggi, Amteshwar Singh

2016-08-01

Remote ischemic preconditioning is a well reported therapeutic strategy that induces cardioprotective effects but the underlying intracellular mechanisms have not been widely explored. The current study was designed to investigate the involvement of TRP and especially TRPV channels in remote hind limb preconditioning-induced cardioprotection. Remote hind limb preconditioning stimulus (4 alternate cycles of inflation and deflation of 5 min each) was delivered using a blood pressure cuff tied on the hind limb of the anesthetized rat. Using Langendorff's system, the heart was perfused and subjected to 30-min ischemia and 120-min reperfusion. The myocardial injury was assessed by measuring infarct size, lactate dehydrogenase (LDH), creatine kinase (CK), LVDP, +dp/dtmax, -dp/dtmin, heart rate, and coronary flow rate. Gadolinium, TRP blocker, and ruthenium red, TRPV channel blocker, were employed as pharmacological tools. Remote hind limb preconditioning significantly reduced the infarct size, LDH release, CK release and improved coronary flow rate, hemodynamic parameters including LVDP, +dp/dtmax, -dp/dtmin, and heart rate. However, gadolinium (7.5 and 15 mg kg(-1)) and ruthenium red (4 and 8 mg kg(-1)) significantly attenuated the cardioprotective effects suggesting the involvement of TRP especially TRPV channels in mediating remote hind limb preconditioning-induced cardioprotection. Remote hind limb preconditioning stimulus possibly activates TRPV channels on the heart or sensory nerve fibers innervating the heart to induce cardioprotective effects. Alternatively, remote hind limb preconditioning stimulus may also activate the mechanosensitive TRP and especially TRPV channels on the sensory nerve fibers innervating the skeletal muscles to trigger cardioprotective neurogenic signaling cascade. The cardioprotective effects of remote hind limb preconditioning may be mediated via activation of mechanosensitive TRP and especially TRPV channels.

40 CFR 1065.518 - Engine preconditioning.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 33 2014-07-01 2014-07-01 false Engine preconditioning. 1065.518... CONTROLS ENGINE-TESTING PROCEDURES Performing an Emission Test Over Specified Duty Cycles § 1065.518 Engine preconditioning. (a) This section applies for engines where measured emissions are affected by prior operation...

Analysis of physics-based preconditioning for single-phase subchannel equations

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

Hansel, J. E.; Ragusa, J. C.; Allu, S.

2013-07-01

The (single-phase) subchannel approximations are used throughout nuclear engineering to provide an efficient flow simulation because the computational burden is much smaller than for computational fluid dynamics (CFD) simulations, and empirical relations have been developed and validated to provide accurate solutions in appropriate flow regimes. Here, the subchannel equations have been recast in a residual form suitable for a multi-physics framework. The Eigen spectrum of the Jacobian matrix, along with several potential physics-based preconditioning approaches, are evaluated, and the the potential for improved convergence from preconditioning is assessed. The physics-based preconditioner options include several forms of reduced equations that decouplemore » the subchannels by neglecting crossflow, conduction, and/or both turbulent momentum and energy exchange between subchannels. Eigen-scopy analysis shows that preconditioning moves clusters of eigenvalues away from zero and toward one. A test problem is run with and without preconditioning. Without preconditioning, the solution failed to converge using GMRES, but application of any of the preconditioners allowed the solution to converge. (authors)« less

Potassium channels in brain mitochondria.

PubMed

Bednarczyk, Piotr

2009-01-01

Potassium channels are the most widely distributed class of ion channels. These channels are transmembrane proteins known to play important roles in both normal and pathophysiological functions in all cell types. Various potassium channels are recognised as potential therapeutic targets in the treatment of Parkinson's disease, Alzheimer's disease, brain/spinal cord ischaemia and sepsis. In addition to their importance as therapeutic targets, certain potassium channels are known for their beneficial roles in anaesthesia, cardioprotection and neuroprotection. Some types of potassium channels present in the plasma membrane of various cells have been found in the inner mitochondrial membrane as well. Potassium channels have been proposed to regulate mitochondrial membrane potential, respiration, matrix volume and Ca(+) ion homeostasis. It has been proposed that mitochondrial potassium channels mediate ischaemic preconditioning in various tissues. However, the specificity of a pharmacological agents and the mechanisms underlying their effects on ischaemic preconditioning remain controversial. The following potassium channels from various tissues have been identified in the inner mitochondrial membrane: ATP-regulated (mitoK(ATP)) channel, large conductance Ca(2+)-regulated (mitoBK(Ca)) channel, intermediate conductance Ca(2+)-regulated (mitoIK(Ca)) channel, voltage-gated (mitoKv1.3 type) channel, and twin-pore domain (mitoTASK-3) channel. It has been shown that increased potassium flux into brain mitochondria induced by either the mitoK(ATP) channel or mitoBK(Ca) channel affects the beneficial effects on neuronal cell survival under pathological conditions. Recently, differential distribution of mitoBK(Ca) channels has been observed in neuronal mitochondria. These findings may suggest a neuroprotective role for the mitoBK(Ca) channel in specific brain structures. This minireview summarises current data on brain mitochondrial potassium channels and the efforts to identify their molecular correlates.

Optimal preconditioning of lattice Boltzmann methods

NASA Astrophysics Data System (ADS)

Izquierdo, Salvador; Fueyo, Norberto

2009-09-01

A preconditioning technique to accelerate the simulation of steady-state problems using the single-relaxation-time (SRT) lattice Boltzmann (LB) method was first proposed by Guo et al. [Z. Guo, T. Zhao, Y. Shi, Preconditioned lattice-Boltzmann method for steady flows, Phys. Rev. E 70 (2004) 066706-1]. The key idea in this preconditioner is to modify the equilibrium distribution function in such a way that, by means of a Chapman-Enskog expansion, a time-derivative preconditioner of the Navier-Stokes (NS) equations is obtained. In the present contribution, the optimal values for the free parameter γ of this preconditioner are searched both numerically and theoretically; the later with the aid of linear-stability analysis and with the condition number of the system of NS equations. The influence of the collision operator, single- versus multiple-relaxation-times (MRT), is also studied. Three steady-state laminar test cases are used for validation, namely: the two-dimensional lid-driven cavity, a two-dimensional microchannel and the three-dimensional backward-facing step. Finally, guidelines are suggested for an a priori definition of optimal preconditioning parameters as a function of the Reynolds and Mach numbers. The new optimally preconditioned MRT method derived is shown to improve, simultaneously, the rate of convergence, the stability and the accuracy of the lattice Boltzmann simulations, when compared to the non-preconditioned methods and to the optimally preconditioned SRT one. Additionally, direct time-derivative preconditioning of the LB equation is also studied.

Effect of ozone oxidative preconditioning in preventing early radiation-induced lung injury in rats

PubMed Central

Bakkal, B.H.; Gultekin, F.A.; Guven, B.; Turkcu, U.O.; Bektas, S.; Can, M.

2013-01-01

Ionizing radiation causes its biological effects mainly through oxidative damage induced by reactive oxygen species. Previous studies showed that ozone oxidative preconditioning attenuated pathophysiological events mediated by reactive oxygen species. As inhalation of ozone induces lung injury, the aim of this study was to examine whether ozone oxidative preconditioning potentiates or attenuates the effects of irradiation on the lung. Rats were subjected to total body irradiation, with or without treatment with ozone oxidative preconditioning (0.72 mg/kg). Serum proinflammatory cytokine levels, oxidative damage markers, and histopathological analysis were compared at 6 and 72 h after total body irradiation. Irradiation significantly increased lung malondialdehyde levels as an end-product of lipoperoxidation. Irradiation also significantly decreased lung superoxide dismutase activity, which is an indicator of the generation of oxidative stress and an early protective response to oxidative damage. Ozone oxidative preconditioning plus irradiation significantly decreased malondialdehyde levels and increased the activity of superoxide dismutase, which might indicate protection of the lung from radiation-induced lung injury. Serum tumor necrosis factor alpha and interleukin-1 beta levels, which increased significantly following total body irradiation, were decreased with ozone oxidative preconditioning. Moreover, ozone oxidative preconditioning was able to ameliorate radiation-induced lung injury assessed by histopathological evaluation. In conclusion, ozone oxidative preconditioning, repeated low-dose intraperitoneal administration of ozone, did not exacerbate radiation-induced lung injury, and, on the contrary, it provided protection against radiation-induced lung damage. PMID:23969972

Increased Agrobacterium-mediated transformation and rooting efficiencies in canola (Brassica napus L.) from hypocotyl segment explants

NASA Technical Reports Server (NTRS)

Cardoza, V.; Stewart, C. N.

2003-01-01

An efficient protocol for the production of transgenic Brassica napus cv. Westar plants was developed by optimizing two important parameters: preconditioning time and co-cultivation time. Agrobacterium tumefaciens-mediated transformation was performed using hypocotyls as explant tissue. Two variants of a green fluorescent protein (GFP)-encoding gene--mGFP5-ER and eGFP--both under the constitutive expression of the cauliflower mosaic virus 35S promoter, were used for the experiments. Optimizing the preconditioning time to 72 h and co-cultivation time with Agrobacterium to 48 h provided the increase in the transformation efficiency from a baseline of 4% to 25%. With mGFP5-ER, the transformation rate was 17% and with eGFP it was 25%. Transgenic shoots were selected on 200 mg/l kanamycin. Rooting efficiency was 100% on half-strength Murashige and Skoog medium with 10 g/l sucrose and 0.5 mg/l indole butyric acid in the presence of kanamycin.

40 CFR 92.125 - Pre-test procedures and preconditioning.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 20 2014-07-01 2013-07-01 true Pre-test procedures and preconditioning... PROGRAMS (CONTINUED) CONTROL OF AIR POLLUTION FROM LOCOMOTIVES AND LOCOMOTIVE ENGINES Test Procedures § 92.125 Pre-test procedures and preconditioning. (a) Locomotive testing. (1) Determine engine lubricating...

Increased interleukin-1β levels following low dose MDMA induces tolerance against the 5-HT neurotoxicity produced by challenge MDMA

PubMed Central

2011-01-01

Background Preconditioning is a phenomenon by which tolerance develops to injury by previous exposure to a stressor of mild severity. Previous studies have shown that single or repeated low dose MDMA can attenuate 5-HT transporter loss produced by a subsequent neurotoxic dose of the drug. We have explored the mechanism of delayed preconditioning by low dose MDMA. Methods Male Dark Agouti rats were given low dose MDMA (3 mg/kg, i.p.) 96 h before receiving neurotoxic MDMA (12.5 mg/kg, i.p.). IL-1β and IL1ra levels and 5-HT transporter density in frontal cortex were quantified at 1 h, 3 h or 7 days. IL-1β, IL-1ra and IL-1RI were determined between 3 h and 96 h after low dose MDMA. sIL-1RI combined with low dose MDMA or IL-1β were given 96 h before neurotoxic MDMA and toxicity assessed 7 days later. Results Pretreatment with low dose MDMA attenuated both the 5-HT transporter loss and elevated IL-1β levels induced by neurotoxic MDMA while producing an increase in IL-1ra levels. Low dose MDMA produced an increase in IL-1β at 3 h and in IL-1ra at 96 h. sIL-1RI expression was also increased after low dose MDMA. Coadministration of sIL-1RI (3 μg, i.c.v.) prevented the protection against neurotoxic MDMA provided by low dose MDMA. Furthermore, IL-1β (2.5 pg, intracortical) given 96 h before neurotoxic MDMA protected against the 5-HT neurotoxicity produced by the drug, thus mimicking preconditioning. Conclusions These results suggest that IL-1β plays an important role in the development of delayed preconditioning by low dose MDMA. PMID:22114930

Role of endothelial nitric oxide synthase as a trigger and mediator of isoflurane-induced delayed preconditioning in rabbit myocardium.

PubMed

Chiari, Pascal C; Bienengraeber, Martin W; Weihrauch, Dorothee; Krolikowski, John G; Kersten, Judy R; Warltier, David C; Pagel, Paul S

2005-07-01

Isoflurane produces delayed preconditioning in vivo. The authors tested the hypothesis that endothelial, inducible, or neuronal nitric oxide synthase (NOS) is a trigger or mediator of this protective effect. In the absence or presence of exposure to isoflurane (1.0 minimum alveolar concentration) 24 h before experimentation, pentobarbital-anesthetized rabbits (n = 128) instrumented for hemodynamic measurement received 0.9% saline (control), the nonselective NOS inhibitor N-nitro-l-arginine methyl ester (10 mg/kg), one of two of the selective inducible NOS antagonists aminoguanidine (300 mg/kg) or 1400W (0.5 mg/kg), or the selective neuronal NOS inhibitor 7-nitroindazole (50 mg/kg) administered before exposure to isoflurane (trigger; day 1) or left anterior descending coronary artery occlusion (mediator; day 2). All rabbits underwent 30 min of coronary occlusion followed by 3 h of reperfusion. Tissue samples for reverse-transcription polymerase chain reaction and immunohistochemistry were also obtained in the presence or absence of N-nitro-l-arginine methyl ester with or without isoflurane pretreatment. Isoflurane significantly (P < 0.05) reduced infarct size (23 +/- 5% [mean +/- SD] of the left ventricular area at risk; triphenyltetrazolium chloride staining) as compared with control (42 +/- 7%). N-nitro-l-arginine methyl ester administered before isoflurane or coronary occlusion abolished protection (49 +/- 7 and 43 +/- 10%, respectively). Aminoguanidine, 1400W, and 7-nitroindazole did not alter infarct size or affect isoflurane-induced delayed preconditioning. Isoflurane increased endothelial but not inducible NOS messenger RNA transcription and protein translation immediately and 24 h after administration of the volatile agent. Pretreatment with N-nitro-l-arginine methyl ester attenuated isoflurane-induced increases in endothelial NOS expression. The results suggest that endothelial NOS but not inducible or neuronal NOS is a trigger and mediator of delayed preconditioning by isoflurane in vivo.

Terrorist Innovations in Weapons of Mass Effect: Preconditions, Causes, and Predictive Indicators

DTIC Science & Technology

2010-10-01

into the Martin Marietta Rock Quarry to steal explosives and blasting caps. This should have triggered an investigation from the FBI counterterrorism...Kifner, “In Long Fight With Israel, Hezbollah Tactics Evolved,” The New York Times, July 19, 2000. 48 Martin Dillon, The Dirty War: Covert...includes scientific discovery. Also see Martin Heidegger for a more obtuse expression of a similar idea, ( Martin Heidegger [William Lovitt, transl

40 CFR 85.2218 - Preconditioned idle test-EPA 91.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 18 2011-07-01 2011-07-01 false Preconditioned idle test-EPA 91. 85.2218 Section 85.2218 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS... Tests § 85.2218 Preconditioned idle test—EPA 91. (a) General requirements—(1) Exhaust gas sampling...

40 CFR 86.1232-96 - Vehicle preconditioning.

Code of Federal Regulations, 2013 CFR

2013-07-01

... awaiting testing, to prevent unusual loading of the canisters. During this time care must be taken to... vehicles with multiple canisters in a series configuration, the set of canisters must be preconditioned as... designed for vapor load or purge steps, the service port shall be used during testing to precondition the...

40 CFR 86.1232-96 - Vehicle preconditioning.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 20 2012-07-01 2012-07-01 false Vehicle preconditioning. 86.1232-96... (CONTINUED) CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND ENGINES (CONTINUED) Evaporative... Methanol-Fueled Heavy-Duty Vehicles § 86.1232-96 Vehicle preconditioning. (a) Fuel tank cap(s) of gasoline...

40 CFR 85.2218 - Preconditioned idle test-EPA 91.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 19 2012-07-01 2012-07-01 false Preconditioned idle test-EPA 91. 85... Tests § 85.2218 Preconditioned idle test—EPA 91. (a) General requirements—(1) Exhaust gas sampling algorithm. The analysis of exhaust gas concentrations begins ten seconds after the applicable test mode...

Pseudo-compressibility methods for the incompressible flow equations

NASA Technical Reports Server (NTRS)

Turkel, Eli; Arnone, A.

1993-01-01

Preconditioning methods to accelerate convergence to a steady state for the incompressible fluid dynamics equations are considered. The analysis relies on the inviscid equations. The preconditioning consists of a matrix multiplying the time derivatives. Thus the steady state of the preconditioned system is the same as the steady state of the original system. The method is compared to other types of pseudo-compressibility. For finite difference methods preconditioning can change and improve the steady state solutions. An application to viscous flow around a cascade with a non-periodic mesh is presented.

The Galvanotactic Migration of Keratinocytes is Enhanced by Hypoxic Preconditioning

PubMed Central

Guo, Xiaowei; Jiang, Xupin; Ren, Xi; Sun, Huanbo; Zhang, Dongxia; Zhang, Qiong; Zhang, Jiaping; Huang, Yuesheng

2015-01-01

The endogenous electric field (EF)-directed migration of keratinocytes (galvanotaxis) into wounds is an essential step in wound re-epithelialization. Hypoxia, which occurs immediately after injury, acts as an early stimulus to initiate the healing process; however, the mechanisms for this effect, remain elusive. We show here that the galvanotactic migration of keratinocytes was enhanced by hypoxia preconditioning as a result of the increased directionality rather than the increased motility of keratinocytes. This enhancement was both oxygen tension- and preconditioning time-dependent, with the maximum effects achieved using 2% O2 preconditioning for 6 hours. Hypoxic preconditioning (2% O2, 6 hours) decreased the threshold voltage of galvanotaxis to < 25 mV/mm, whereas this value was between 25 and 50 mV/mm in the normal culture control. In a scratch-wound monolayer assay in which the applied EF was in the default healing direction, hypoxic preconditioning accelerated healing by 1.38-fold compared with the control conditions. Scavenging of the induced ROS by N-acetylcysteine (NAC) abolished the enhanced galvanotaxis and the accelerated healing by hypoxic preconditioning. Our data demonstrate a novel and unsuspected role of hypoxia in supporting keratinocyte galvanotaxis. Enhancing the galvanotactic response of cells might therefore be a clinically attractive approach to induce improved wound healing. PMID:25988491

Moving beyond the welfare standard of psychological well-being for nonhuman primates: the case of chimpanzees.

PubMed

Gluck, John P

2014-04-01

Since 1985, the US Animal Welfare Act and Public Health Service policy have required that researchers using nonhuman primates in biomedical and behavioral research develop a plan "for a physical environment adequate to promote the psychological well-being of primates." In pursuing this charge, housing attributes such as social companionship, opportunities to express species-typical behavior, suitable space for expanded locomotor activity, and nonstressful relationships with laboratory personnel are dimensions that have dominated the discussion. Regulators were careful not to direct a specific set of prescriptions (i.e., engineering standards) for the attainment of these goals, but to leave the design of the programs substantially up to "professional judgment" at the local level. Recently, however, the Institute of Medicine, in its path-finding 2011 report on the necessity of chimpanzee use in research, bypassed this flexible and contingent concept, and instead, required as a central precondition that chimpanzees be housed in "ethologically appropriate" environments. In so doing, obligations of ethical treatment of one great ape species were elevated above the needs of some research. The evolution and significance of this change are discussed.

Polyester modification of the mammalian TRPM8 channel protein: Implications for structure and function

PubMed Central

Bikard, Yann; Chen, Wei; Liu, Tong; Li, Hong; Jendrossek, Dieter; Cohen, Alejandro; Pavlov, Evgeny; Rohacs, Tibor; Zakharian, Eleonora

2013-01-01

SUMMARY The TRPM8 ion channel is expressed in sensory neurons and is responsible for sensing environmental cues such as cold temperatures and chemical compounds, including menthol and icilin. The channel functional activity is regulated by various physical and chemical factors, and is likely to be pre-conditioned by its molecular composition. Our studies indicate that TRPM8 channel forms a structural-functional complex with the polyester, poly-(R)-3hydroxybutyrate (PHB). We identified by mass spectrometry a number of PHB-modified peptides in the N-terminus of the TRPM8 protein and in its extracellular S3–S4 linker. Removal of PHB by enzymatic hydrolysis, and site-directed mutagenesis of both the serine residues that serve as covalent anchors for PHB and adjacent hydrophobic residues that interact with the methyl groups of the polymer, resulted in significant inhibition of TRPM8 channel activity. We conclude that the TRPM8 channel undergoes post-translational modification by PHB and that this modification is required for its normal function. PMID:23850286

Hypophosphorylation of Ribosomal Protein S6 is a Molecular Mechanism Underlying Ischemic Tolerance Induced by either Hibernation or Preconditioning

PubMed Central

Miyake, Shin-ichi; Wakita, Hideaki; Bernstock, Joshua D.; Castri, Paola; Ruetzler, Christl; Miyake, Junko; Lee, Yang-ja; Hallenbeck, John M.

2015-01-01

Thirteen-lined ground squirrels (Ictidomys tridecemlineatus) have an extraordinary capacity to withstand prolonged and profound reductions of blood flow and oxygen delivery to brain without incurring any cellular damage. As such, the hibernation torpor of I. tridecemlineatus provides a valuable model of tolerance to ischemic stress. Herein, we report that during hibernation torpor, a marked reduction in the phosphorylation of the ribosomal protein S6 (rpS6) occurs within the brains of I. tridecemlineatus. Of note, rpS6 phosphorylation was shown to increase in the brains of rats that underwent an occlusion of the middle cerebral artery. However, such an increase was attenuated after the implementation of an ischemic preconditioning paradigm. In addition, cultured cortical neurons treated with the rpS6 kinase (S6K) inhibitors, D-glucosamine or PF4708671, displayed a decrease in rpS6 phosphorylation and a subsequent increase in tolerance to oxygen/glucose deprivation, an in vitro model of ischemic stroke. Collectively, such evidence suggests that the down regulation of rpS6 signal transduction may account for a substantial part of the observed increase in cellular tolerance to brain ischemia that occurs during hibernation torpor and after ischemic preconditioning. Further identification and characterization of the mechanisms used by hibernating species to increase ischemic tolerance may eventually clarify how the loss of homeostatic control that occurs during and after cerebral ischemia in the clinic can ultimately be minimized and/or prevented. PMID:26375300

Sulfiredoxin-1 protects against simulated ischaemia/reperfusion injury in cardiomyocyte by inhibiting PI3K/AKT-regulated mitochondrial apoptotic pathways.

PubMed

Zhang, Jiankai; He, Zhangyou; Guo, Jinhua; Li, Zhe; Wang, Xiaohong; Yang, Chun; Cui, Xiaojun

2016-01-01

Reactive oxygen species (ROS)-triggered cardiac cell injury is recognized as the major contributor for the pathogenesis progression of ischaemic cardiovascular diseases. Sulfiredoxin-1 (Srx-1) is an endogenous antioxidant and exerts the crucial neuroprotective effects in cerebral ischaemia. However, its function and the underlying mechanism in ischaemic heart diseases remain poorly defined. Here, a dramatical decrease in Srx-1 was validated in H9c2 cardiomyocytes upon simulated ischaemia-reperfusion (SI/R) injury. Moreover, Srx-1 protected H9c2 cells from SI/R-injured injury as the evidences that Srx-1 up-regulation attenuated the inhibitory effects on cell viability, lactate dehydrogenase (LDH) and cell apoptosis upon SI/R treatment. Knockdown of Srx-1 accelerated cell injury upon SI/R. Mechanism assay corroborated that SI/R treatment noticeably aggravated the loss of mitochondrial membrane potential (Δψm), which was remarkably abated in Ad-Srx-1 groups. Importantly, Srx-1 elevation substantially reduced cytochrome c release, the activity of caspase-9 and caspase-3, accompany with the subsequent decrease in the cleavage of poly (ADP ribose) polymerase (PARP). Concomitantly, overexpression of Srx-1 also decreased the expression of pro-apoptosis protein Bax and increased anti-apoptotic Bcl-2 expression. Further analysis substantiated that Srx-1 treatment remarkably induced the activation of PI3K/AKT signalling. Preconditioning with LY294002 dramatically decreased Srx-1-enhanced cell resistance to SI/R injury. Importantly, LY294002 mitigated the inhibitory effects of Srx-1 on Δψm loss, cytochrome c release, caspase-9/3 activity, and the expression of Bcl-2 family. Together, these results suggested that Srx-1 might protect cardiomyocyte injury upon SI/R by suppressing PI3K/AKT-mediated mitochondria dependent apoptosis, revealing a promising therapeutic agent against ischaemic cardiovascular diseases. © 2016 The Author(s).

Sensory Preconditioning in Newborn Rabbits: From Common to Distinct Odor Memories

ERIC Educational Resources Information Center

Coureaud, Gerard; Tourat, Audrey; Ferreira, Guillaume

2013-01-01

This study evaluated whether olfactory preconditioning is functional in newborn rabbits and based on joined or independent memory of odorants. First, after exposure to odorants A+B, the conditioning of A led to high responsiveness to odorant B. Second, responsiveness to B persisted after amnesia of A. Third, preconditioning was also functional…

40 CFR 85.2220 - Preconditioned two speed idle test-EPA 91.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 18 2010-07-01 2010-07-01 false Preconditioned two speed idle test-EPA... Warranty Short Tests § 85.2220 Preconditioned two speed idle test—EPA 91. (a) General requirements—(1...-speed mode followed immediately by a first-chance idle mode. (ii) The second-chance test as described...

40 CFR 85.2220 - Preconditioned two speed idle test-EPA 91.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 18 2011-07-01 2011-07-01 false Preconditioned two speed idle test-EPA... Warranty Short Tests § 85.2220 Preconditioned two speed idle test—EPA 91. (a) General requirements—(1...-speed mode followed immediately by a first-chance idle mode. (ii) The second-chance test as described...

Neuroprotective effects of ischemic preconditioning on hippocampal CA1 pyramidal neurons through maintaining calbindin D28k immunoreactivity following subsequent transient cerebral ischemia

PubMed Central

Kim, In Hye; Jeon, Yong Hwan; Lee, Tae-Kyeong; Cho, Jeong Hwi; Lee, Jae-Chul; Park, Joon Ha; Ahn, Ji Hyeon; Shin, Bich-Na; Kim, Yang Hee; Hong, Seongkweon; Yan, Bing Chun; Won, Moo-Ho; Lee, Yun Lyul

2017-01-01

Ischemic preconditioning elicited by a non-fatal brief occlusion of blood flow has been applied for an experimental therapeutic strategy against a subsequent fatal ischemic insult. In this study, we investigated the neuroprotective effects of ischemic preconditioning (2-minute transient cerebral ischemia) on calbindin D28k immunoreactivity in the gerbil hippocampal CA1 area following a subsequent fatal transient ischemic insult (5-minute transient cerebral ischemia). A large number of pyramidal neurons in the hippocampal CA1 area died 4 days after 5-minute transient cerebral ischemia. Ischemic preconditioning reduced the death of pyramidal neurons in the hippocampal CA1 area. Calbindin D28k immunoreactivity was greatly attenuated at 2 days after 5-minute transient cerebral ischemia and it was hardly detected at 5 days post-ischemia. Ischemic preconditioning maintained calbindin D28k immunoreactivity after transient cerebral ischemia. These findings suggest that ischemic preconditioning can attenuate transient cerebral ischemia-caused damage to the pyramidal neurons in the hippocampal CA1 area through maintaining calbindin D28k immunoreactivity. PMID:28761424

SirT1 mediates hyperbaric oxygen preconditioning-induced ischemic tolerance in rat brain

PubMed Central

Yan, Wenjun; Fang, Zongping; Yang, Qianzi; Dong, Hailong; Lu, Yan; Lei, Chong; Xiong, Lize

2013-01-01

Our previous studies have shown that hyperbaric oxygen preconditioning (HBO-PC) induces tolerance to cerebral ischemia/reperfusion (I/R). This study aimed to investigate whether SirT1, a class III histone deacetylase, is involved in neuroprotection elicited by HBO-PC in animal and cell culture models of ischemia. Rats were subjected to middle cerebral artery occlusion for 120 minutes after HBO-PC (once a day for 5 days). Primary cultured cortical neurons were exposed to 2 hours of HBO-PC after 2 hours of oxygen–glucose deprivation (OGD). We showed that HBO-PC increased SirT1 protein and mRNA expression, promoted neurobehavioral score, reduced infarct volume, and improved morphology at 24 hours and 7 days after cerebral I/R. Neuroprotection of HBO-PC was attenuated by SirT1 inhibitor EX527 and SirT1 knockdown by short interfering RNA (siRNA), whereas it was mimicked by SirT1 activator resveratrol. Furthermore, HBO-PC enhanced SirT1 expression and cell viability and reduced lactate dehydrogenase release 24 hours after OGD/re-oxygenation. The neuroprotective effect of HBO-PC was emulated through upregulating SirT1 and, reversely, attenuated through downregulating SirT1. The modulation of SirT1 was made by adenovirus infection carrying SirT1 or SirT1 siRNA. Besides, SirT1 increased B-cell lymphoma 2 (Bcl-2) expression and decrease cleaved caspase 3. These results indicate that SirT1 mediates HBO-PC-induced tolerance to cerebral I/R through inhibition of apoptosis. PMID:23299244

S{sub 2}SA preconditioning for the S{sub n} equations with strictly non negative spatial discretization

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

Bruss, D. E.; Morel, J. E.; Ragusa, J. C.

2013-07-01

Preconditioners based upon sweeps and diffusion-synthetic acceleration have been constructed and applied to the zeroth and first spatial moments of the 1-D S{sub n} transport equation using a strictly non negative nonlinear spatial closure. Linear and nonlinear preconditioners have been analyzed. The effectiveness of various combinations of these preconditioners are compared. In one dimension, nonlinear sweep preconditioning is shown to be superior to linear sweep preconditioning, and DSA preconditioning using nonlinear sweeps in conjunction with a linear diffusion equation is found to be essentially equivalent to nonlinear sweeps in conjunction with a nonlinear diffusion equation. The ability to use amore » linear diffusion equation has important implications for preconditioning the S{sub n} equations with a strictly non negative spatial discretization in multiple dimensions. (authors)« less

Hybrid preconditioning for iterative diagonalization of ill-conditioned generalized eigenvalue problems in electronic structure calculations

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

Cai, Yunfeng, E-mail: yfcai@math.pku.edu.cn; Department of Computer Science, University of California, Davis 95616; Bai, Zhaojun, E-mail: bai@cs.ucdavis.edu

2013-12-15

The iterative diagonalization of a sequence of large ill-conditioned generalized eigenvalue problems is a computational bottleneck in quantum mechanical methods employing a nonorthogonal basis for ab initio electronic structure calculations. We propose a hybrid preconditioning scheme to effectively combine global and locally accelerated preconditioners for rapid iterative diagonalization of such eigenvalue problems. In partition-of-unity finite-element (PUFE) pseudopotential density-functional calculations, employing a nonorthogonal basis, we show that the hybrid preconditioned block steepest descent method is a cost-effective eigensolver, outperforming current state-of-the-art global preconditioning schemes, and comparably efficient for the ill-conditioned generalized eigenvalue problems produced by PUFE as the locally optimal blockmore » preconditioned conjugate-gradient method for the well-conditioned standard eigenvalue problems produced by planewave methods.« less

Preconditioning with the traditional Chinese medicine Huang-Lian-Jie-Du-Tang initiates HIF-1α-dependent neuroprotection against cerebral ischemia in rats.

PubMed

Zhang, Qichun; Bian, Huimin; Li, Yu; Guo, Liwei; Tang, Yuping; Zhu, Huaxu

2014-06-11

Huang-Lian-Jie-Du-Tang (HLJDT) is a classical heat-clearing and detoxicating formula of traditional Chinese medicine that is widely used to treat stroke. The present study was designed to investigate the effects of HLJDT preconditioning on neurons under oxygen and glucose deprivation (OGD) and rats subjected to middle cerebral artery occlusion (MCAO). A stroke model of rats was obtained through MCAO. Following HLJDT preconditioning, the cerebral infarction volume, cerebral water content, and neurological deficient score were determined. Cerebral cortical neurons cultured in vitro were preconditioned with HLJDT and then subjected to OGD treatment. The release of lactate dehydrogenase (LDH) from neurons was detected. The levels of hypoxia-inducible factor-1α (HIF-1α) and PI3K/Akt signaling were analyzed by western blotting, and the levels of erythropoietin (EPO) and vascular endothelial growth factor (VEGF) in the supernatant of the neurons and the plasma of MCAO rats were measured through a radioimmunological assay. The apoptosis and proliferation of neurons were analyzed by immunohistochemistry. HLJDT preconditioning significantly reduced the cerebral infarction volume and cerebral water content and ameliorated the neurological deficient score of MCAO rats. In addition, HLJDT preconditioning protected neurons against OGD. Increased HIF-1α, EPO, and VEGF levels and the activation of PI3K/Akt signaling were observed as a result of HLJDT preconditioning. Furthermore, HLJDT preconditioning was found to inhibit ischemia-induced neuron apoptosis and to promote neuron proliferation under conditions of ischemia/reperfusion. Both rats and neurons subjected to HLJDT preconditioning were able to resist ischemia/reperfusion or hypoxia injury through the inhibition of apoptosis and the enhancement of proliferation, and these effects were primarily dependent on the activation of the PI3K/Akt signaling pathway and HIF-1α. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Toll-like receptor 3 pre-conditioning increases the therapeutic efficacy of umbilical cord mesenchymal stromal cells in a dextran sulfate sodium-induced colitis model.

PubMed

Fuenzalida, Patricia; Kurte, Mónica; Fernández-O'ryan, Catalina; Ibañez, Cristina; Gauthier-Abeliuk, Melanie; Vega-Letter, Ana María; Gonzalez, Paz; Irarrázabal, Carlos; Quezada, Nataly; Figueroa, Fernando; Carrión, Flavio

2016-05-01

Immunomodulatory properties of human umbilical cord-derived mesenchymal stromal cells (UCMSCs) can be differentially modulated by toll-like receptors (TLR) agonists. Here, the therapeutic efficacy of short TLR3 and TLR4 pre-conditioning of UCMSCs was evaluated in a dextran sulfate sodium (DSS)-induced colitis in mice. The novelty of this study is that although modulation of human MSCs activity by TLRs is not a new concept, this is the first time that short TLR pre-conditioning has been carried out in a murine inflammatory model of acute colitis. C57BL/6 mice were exposed to 2.5% dextran sulfate sodium (DSS) in drinking water ad libitum for 7 days. At days 1 and 3, mice were injected intraperitoneally with 1 × 10(6) UCMSCs untreated or TLR3 and TLR4 pre-conditioned UCMSCs. UCMSCs were pre-conditioned with poly(I:C) for TLR3 and LPS for TLR4 for 1 h at 37°C and 5% CO2. We evaluated clinical signs of disease and body weights daily. At the end of the experiment, colon length and histological changes were assessed. poly(I:C) pre-conditioned UCMSCs significantly ameliorated the clinical and histopathological severity of DSS-induced colitis compared with UCMSCs or LPS pre-conditioned UCMSCs. In contrast, infusion of LPS pre-conditioned UCMSCs significantly increased clinical signs of disease, colon shortening and histological disease index in DSS-induced colitis. These results show that short in vitro TLR3 pre-conditioning with poly(I:C) enhances the therapeutic efficacy of UCMSCs, which is a major breakthrough for developing improved treatments to patients with inflammatory bowel disease. Copyright © 2016 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

Brain Injury Lesion Imaging Using Preconditioned Quantitative Susceptibility Mapping without Skull Stripping.

PubMed

Soman, S; Liu, Z; Kim, G; Nemec, U; Holdsworth, S J; Main, K; Lee, B; Kolakowsky-Hayner, S; Selim, M; Furst, A J; Massaband, P; Yesavage, J; Adamson, M M; Spincemallie, P; Moseley, M; Wang, Y

2018-04-01

Identifying cerebral microhemorrhage burden can aid in the diagnosis and management of traumatic brain injury, stroke, hypertension, and cerebral amyloid angiopathy. MR imaging susceptibility-based methods are more sensitive than CT for detecting cerebral microhemorrhage, but methods other than quantitative susceptibility mapping provide results that vary with field strength and TE, require additional phase maps to distinguish blood from calcification, and depict cerebral microhemorrhages as bloom artifacts. Quantitative susceptibility mapping provides universal quantification of tissue magnetic property without these constraints but traditionally requires a mask generated by skull-stripping, which can pose challenges at tissue interphases. We evaluated the preconditioned quantitative susceptibility mapping MR imaging method, which does not require skull-stripping, for improved depiction of brain parenchyma and pathology. Fifty-six subjects underwent brain MR imaging with a 3D multiecho gradient recalled echo acquisition. Mask-based quantitative susceptibility mapping images were created using a commonly used mask-based quantitative susceptibility mapping method, and preconditioned quantitative susceptibility images were made using precondition-based total field inversion. All images were reviewed by a neuroradiologist and a radiology resident. Ten subjects (18%), all with traumatic brain injury, demonstrated blood products on 3D gradient recalled echo imaging. All lesions were visible on preconditioned quantitative susceptibility mapping, while 6 were not visible on mask-based quantitative susceptibility mapping. Thirty-one subjects (55%) demonstrated brain parenchyma and/or lesions that were visible on preconditioned quantitative susceptibility mapping but not on mask-based quantitative susceptibility mapping. Six subjects (11%) demonstrated pons artifacts on preconditioned quantitative susceptibility mapping and mask-based quantitative susceptibility mapping; they were worse on preconditioned quantitative susceptibility mapping. Preconditioned quantitative susceptibility mapping MR imaging can bring the benefits of quantitative susceptibility mapping imaging to clinical practice without the limitations of mask-based quantitative susceptibility mapping, especially for evaluating cerebral microhemorrhage-associated pathologies, such as traumatic brain injury. © 2018 by American Journal of Neuroradiology.

Evidence that the adenosine A3 receptor may mediate the protection afforded by preconditioning in the isolated rabbit heart.

PubMed

Liu, G S; Richards, S C; Olsson, R A; Mullane, K; Walsh, R S; Downey, J M

1994-07-01

Agonists selective for the A1 adenosine receptor mimic the protective effect of ischaemic preconditioning against infarction in the rabbit heart. Unselective adenosine antagonists block this protection but, paradoxically, the A1 adenosine receptor selective antagonist 8-cyclopentyl- 1,3-dipropylxanthine (DPCPX) does not. The aim of this study was to test the hypothesis that the newly described A3 adenosine receptor, which has an agonist profile similar to the A1 receptor but is insensitive to DPCPX, might mediate preconditioning. Isolated rabbit hearts perfused with Krebs buffer experienced 30 min of regional ischaemia followed by 120 min of reperfusion. Infarct size was measured by tetrazolium staining. In control hearts infarction was 32.2(SEM 1.5)% of the risk zone. Preconditioning by 5 min ischaemia and 10 min reperfusion reduced infarct size to 8.8(2.3)%. Replacing the regional ischaemia with 5 min perfusion with 10 microM adenosine or 65 nM N6-[2-(4-aminophenyl)ethyl]adenosine (APNEA), an adenosine A3 receptor agonist, was equally protective. The unselective antagonist 8-p-sulphophenyl theophylline at 100 microM abolished protection by preconditioning, adenosine, and APNEA, but 200 nM DPCPX did not block protection by any of the interventions. Likewise the potent but unselective A3 receptor antagonist 8-(4-carboxyethenylphenyl)-1,3-dipropylxanthine (BW A1433) completely blocked protection from ischaemic preconditioning. Because protection against infarction afforded by ischaemic preconditioning, adenosine, or the A3 receptor agonist APNEA could not be blocked by DPCPX and because the potent A3 receptor antagonist BW A1433 blocked protection from ischaemic preconditioning, these data indicate that the protection of preconditioning is not exclusively mediated by the adenosine A1 receptor in rabbit heart and could involve the A3 receptor.

Cardioprotective Effects of Transfusion of Late-Phase Preconditioned Plasma May Be Induced by Activating the Reperfusion Injury Salvage Kinase Pathway but Not the Survivor Activating Factor Enhancement Pathway in Rats.

PubMed

Zhao, Yang; Zheng, Zhi-Nan; Pi, Yan-Na; Liang, Xue; Jin, San-Qing

2017-01-01

A previous study in our laboratory demonstrated that transfusion of plasma collected at the late phase of remote ischemic preconditioning (RIPC) could reduce myocardial infarct size. Here, we tested whether the reperfusion injury salvage kinase (RISK) and survivor activating factor enhancement (SAFE) pathways are involved in transferring protection. In a two-part study, donor rats ( n = 3) donated plasma 48 hours after RIPC (preconditioned plasma) or control (nonpreconditioned plasma). Normal (part 1) or ischemic (part 2) myocardia were collected from recipients ( n = 6) 24 hours after receiving normal saline, nonpreconditioned plasma, and preconditioned plasma or after further suffering ischemia reperfusion. Western blot was performed to analyze STAT3, Akt, and Erk1/2 phosphorylation in normal and ischemic myocardium (central area and border area). In normal myocardia, preconditioned plasma increased Akt and Erk1/2 phosphorylation significantly compared to nonpreconditioned plasma and normal saline; no STAT3 phosphorylation was detected. In ischemic myocardia, preconditioned plasma increased Akt and Erk1/2 phosphorylation significantly in both central and border areas compared to other fluids; no significant difference in STAT3 phosphorylation occurred among groups. Transfusion of preconditioned plasma collected at the late phase of RIPC could activate the RISK but not SAFE pathway, suggesting that RISK pathway may be involved in transferring protection.

HSF1 and NF-κB p65 participate in the process of exercise preconditioning attenuating pressure overload-induced pathological cardiac hypertrophy

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

Xu, Tongyi; Department of Cardiothoracic Surgery, Changhai Hospital, Second Military Medical University, Shanghai; Zhang, Ben

Pathological cardiac hypertrophy, often accompanied by hypertension, aortic stenosis and valvular defects, is typically associated with myocyte remodeling and cardiac dysfunction. Exercise preconditioning (EP) has been proven to enhance the tolerance of the myocardium to cardiac ischemia-reperfusion injury. However, the effects of EP in pathological cardiac hypertrophy are rarely reported. 10-wk-old male Sprague–Dawley rats (n = 80) were randomly divided into four groups: sham, TAC, EP + sham and EP + TAC. Two EP groups were subjected to 4 weeks of treadmill training, and the EP + TAC and TAC groups were followed by TAC operations. The sham and EP + sham groups underwent the same operation without aortic constriction.more » Eight weeks after the surgery, we evaluated the effects of EP by echocardiography, morphology, and histology and observed the expressions of the associated proteins. Compared with the respective control groups, hypertrophy-related indicators were significantly increased in the TAC and EP + TAC groups (p < 0.05). However, between the TAC and EP + TAC groups, all of these changes were effectively inhibited by EP treatment (p < 0.05). Furthermore, EP treatment upregulated the expression of HSF1 and HSP70, increased the HSF1 levels in the nuclear fraction, inhibited the expression of the NF-κB p65 subunit, decreased the NF-κB p65 subunit levels in the nuclear fraction, and reduced the IL2 levels in the myocardia of rats. EP could effectively reduce the cardiac hypertrophic responses induced by TAC and may play a protective role by upregulating the expressions of HSF1 and HSP70, activating HSF1 and then inhibiting the expression of NF-κB p65 and nuclear translocation. - Highlights: • EP could effectively reduce the cardiac hypertrophic responses induced by TAC. • EP may play a protective role by upregulating the expressions of HSF1 and HSP70 and then activating HSF1. • EP may play a protective role by inhibiting the expression of NF-κB p65 and nuclear translocation.« less

40 CFR 86.153-98 - Vehicle and canister preconditioning; refueling test.

Code of Federal Regulations, 2012 CFR

2012-07-01

... controlled to 50±25 grains of water vapor per pound of dry air) maintained at a nominal flow rate of 0.8 cfm... preconditioning; refueling test. (a) Vehicle and canister preconditioning. Vehicles and vapor storage canisters... at least 1200 canister bed volumes of ambient air (with humidity controlled to 50±25 grains of water...

40 CFR 86.153-98 - Vehicle and canister preconditioning; refueling test.

Code of Federal Regulations, 2011 CFR

2011-07-01

... controlled to 50±25 grains of water vapor per pound of dry air) maintained at a nominal flow rate of 0.8 cfm... preconditioning; refueling test. (a) Vehicle and canister preconditioning. Vehicles and vapor storage canisters... at least 1200 canister bed volumes of ambient air (with humidity controlled to 50±25 grains of water...

40 CFR 86.153-98 - Vehicle and canister preconditioning; refueling test.

Code of Federal Regulations, 2014 CFR

2014-07-01

... controlled to 50±25 grains of water vapor per pound of dry air) maintained at a nominal flow rate of 0.8 cfm... preconditioning; refueling test. (a) Vehicle and canister preconditioning. Vehicles and vapor storage canisters... at least 1200 canister bed volumes of ambient air (with humidity controlled to 50±25 grains of water...

40 CFR 86.153-98 - Vehicle and canister preconditioning; refueling test.

Code of Federal Regulations, 2010 CFR

2010-07-01

... controlled to 50±25 grains of water vapor per pound of dry air) maintained at a nominal flow rate of 0.8 cfm... preconditioning; refueling test. (a) Vehicle and canister preconditioning. Vehicles and vapor storage canisters... at least 1200 canister bed volumes of ambient air (with humidity controlled to 50±25 grains of water...

40 CFR 86.153-98 - Vehicle and canister preconditioning; refueling test.

Code of Federal Regulations, 2013 CFR

2013-07-01

... controlled to 50±25 grains of water vapor per pound of dry air) maintained at a nominal flow rate of 0.8 cfm... preconditioning; refueling test. (a) Vehicle and canister preconditioning. Vehicles and vapor storage canisters... at least 1200 canister bed volumes of ambient air (with humidity controlled to 50±25 grains of water...

The In Vitro Differentiation of GDNF Gene-Engineered Amniotic Fluid-Derived Stem Cells into Renal Tubular Epithelial-Like Cells.

PubMed

Lu, Ying; Wang, Zhuojun; Chen, Lu; Wang, Jia; Li, Shulin; Liu, Caixia; Sun, Dong

2018-05-01

Amniotic fluid is an alternative source of stem cells, and human amniotic fluid-derived stem cells (AFSCs) obtained from a small amount of amniotic fluid collected during the second trimester represent a novel source for use in regenerative medicine. These AFSCs are characterized by lower diversity, a higher proliferation rate, and a wider differentiation capability than adult mesenchymal stem cells. AFSCs are selected based on the cell surface marker c-kit receptor (CD117) using immunomagnetic sorting. Glial cell line-derived neurotrophic factor (GDNF) is expressed during early kidney development and regulates the proliferation and differentiation of stem cells in vitro. In this study, c-kit-sorted AFSCs were induced toward osteogenic or adipogenic differentiation. AFSCs engineered via the insertion of GDNF were cocultured with mouse renal tubular epithelial cells (mRTECs), which were preconditioned by hypoxia-reoxygenation in vitro. After coculture for 8 days, AFSCs differentiation into epithelial-like cells was evaluated by performing immunofluorescence, flow cytometry, and quantitative real-time polymerase chain reaction to identify cells expressing the renal epithelial markers, cytokeratin 18 (CK18), E-cadherin, aquaporin-1 (AQP1), and paired box 2 gene (Pax2). The GDNF gene enhanced AFSCs differentiation into RTECs. AFSCs possess self-renewal ability and multiple differentiation potential and thus represent a new source of stem cells.

Erection capability is potentiated by long-term sildenafil treatment: role of blood flow-induced endothelial nitric-oxide synthase phosphorylation.

PubMed

Musicki, Biljana; Champion, Hunter C; Becker, Robyn E; Liu, Tongyun; Kramer, Melissa F; Burnett, Arthur L

2005-07-01

Despite demonstrated clinical efficacy of sildenafil for the temporary treatment of erectile dysfunction, the possibility that sildenafil used long-term durably augments erectile ability remains unclear. We investigated whether continuous long-term administration of sildenafil at clinically relevant levels to aged rats "primes" the penis for improved erectile ability and involves nitric oxide (NO) or RhoA/Rho-kinase signaling pathways. In aged, but not young rats, sildenafil prolonged erection and increased the protein expressions of phosphorylated endothelial NO synthase (eNOS) at serine-1177 and phosphorylated Akt at serine-473 in penes. Only in the young rat penis, protein expressions of phosphodiesterase-5 and phosphomyosin phosphatase target subunit 1, a marker of Rho-kinase activity, were increased by sildenafil. Sildenafil inhibited phosphodiesterase-5 activity in penes of young and aged rats coincident with assayed free plasma levels of the drug equivalent to clinically therapeutic measurements. We conclude that erectile ability can be enhanced under preconditions of erectile impairment by long-term inhibition of phosphodiesterase-5 and that the effect is mediated by Akt-dependent eNOS phosphorylation. The lack of erectile ability enhancement in young rats by long-term phosphodiesterase-5 inhibition may relate to restrained NO signaling by phosphodiesterase-5 up-regulation, lack of incremental Akt and eNOS phosphorylation, and heightened Rho-kinase signaling in the penis.

Space disposal of nuclear wastes. Volume 1: Socio-political aspects

NASA Technical Reports Server (NTRS)

Laporte, T.; Rochlin, G. I.; Metlay, D.; Windham, P.

1976-01-01

The history and interpretation of radioactive waste management in the U.S., criteria for choosing from various options for waste disposal, and the impact of nuclear power growth from 1975 to 2000 are discussed. Preconditions for the existence of high level wastes in a form suitable for space disposal are explored. The role of the NASA space shuttle program in the space disposal of nuclear wastes, and the impact on program management, resources and regulation are examined.

Rapamycin Promotes the Survival and Adipogenesis of Ischemia-Challenged Adipose Derived Stem Cells by Improving Autophagy.

PubMed

Li, Chichi; Ye, Lechi; Yang, Li; Yu, Xiaofang; He, Yucang; Chen, Zhuojie; Li, Liqun; Zhang, Dan

2017-01-01

Ischemia is one of the main causes of the high rate of absorption of transplanted autologous fat. Autophagy allows cells to survive by providing energy under starvation. Rapamycin has been found to play a role in promoting autophagy. In this study, we investigated whether rapamycin participates in the survival and adipogenesis of ischemia-challenged adipose-derived stem cells (ADSCs) by regulating autophagy. Before the cells were exposed to oxygen-glucose deprivation (OGD), a simulated ischemic microenvironment, the level of autophagy was reduced or increased by lentiviral transfection with short hairpin RNA targeting microtubule-associated protein 1-light chain 3 gene (shRNA-LC3) or treatment with rapamycin, respectively. The level of autophagy was assessed by western blotting, transmission electron microscopythen the apoptosis ratio was determined through terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) and flow cytometry. Adipogenesis was further evaluated by oil red O staining and the expressions level of some specific proteins for adipocytes. shRNA-LC3 and rapamycin treatment effectively decreased and improved the level of autophagy in cells with or without OGD challenge, respectively. In addition, autophagy inhibition increased the apoptosis rate and activated caspase-3 expression level in response to OGD, and these were markedly inhibited by rapamycin preconditioning. During adipogenesis, autophagy inhibition decreased not only oil droplet accumulation but also lipoprotein lipase (LPL) and peroxisome proliferator-activated receptor gamma (PPARγ) expression in cells with or without OGD challenge. However, autophagy promotion by rapamycin increased oil droplet accumulation and LPL and PPARγ expression. Rapamycin may promote the survival and adipogenesis of ischemia-challenged ADSCs by upregulating autophagy. © 2017 The Author(s). Published by S. Karger AG, Basel.

The time dependence of the effect of ischemic preconditioning on successive sprint swimming performance.

PubMed

Lisbôa, Felipe D; Turnes, Tiago; Cruz, Rogério S O; Raimundo, João A G; Pereira, Gustavo S; Caputo, Fabrizio

2017-05-01

The present study aimed to determine the effects of ischemic preconditioning on performance in three successive 50-m swimming trials and to measure stroke rate, stroke length and blood lactate accumulation. Counterbalanced, repeated-measures cross-over study. On two separate days, eleven competitive male swimmers (20±3 years, 182±5cm, 77±5kg) performed three successive 50-m trials in a 50-m swimming pool, preceded by intermittent bilateral cuff inflation (4× 5-min of blood flow restriction+5-min of cuff deflation) at either 220 for thighs and 180mmHg for arms (ischemic preconditioning) or 20mmHg for both limbs (control-treatment). The 50-m trials were conducted 1-, 2-, and 8-h after the procedure. While no ergogenic effect of ischemic preconditioning was observed for 1-h (0.4%, 95% confidence limits of ±0.6%, p=0.215), there were clear beneficial effects of ischemic preconditioning on 2- and 8-h (1.0% and 1.2%, respectively; 95% confidence limits of ±0.6% in both cases, p≤0.002). Furthermore, ischemic preconditioning increased blood lactate accumulation in 2-(p<0.001) and 8-h (p=0.010) and stroke rate for 2- and 8-h in specific 10-m segments (p<0.05). These findings suggest a time-dependent effect of ischemic preconditioning on 50-m swimming performance for competitive athletes, with the time window of the beneficial effect starting after about 2-h and lasting for at least 8-h after ischemic preconditioning. This change in performance was accompanied by an increase in blood lactate accumulation and faster strokes in front crawl. Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Remote ischemic preconditioning and endothelial function in patients with acute myocardial infarction and primary PCI.

PubMed

Manchurov, Vladimir; Ryazankina, Nadezda; Khmara, Tatyana; Skrypnik, Dmitry; Reztsov, Roman; Vasilieva, Elena; Shpektor, Alexander

2014-07-01

Remote ischemic preconditioning by transient limb ischemia reduces myocardial ischemia-reperfusion injury in patients undergoing percutaneous coronary intervention. The aim of the study we report here was to assess the effect of remote ischemic preconditioning on endothelial function in patients with acute myocardial infarction who underwent primary percutaneous coronary intervention. Forty-eight patients with acute myocardial infarction were enrolled. All participants were randomly divided into 2 groups. In Group I (n = 23), remote ischemic preconditioning was performed before primary percutaneous coronary intervention (intermittent arm ischemia-reperfusion through 4 cycles of 5-minute inflation and 5-minute deflation of a blood-pressure cuff to 200 mm Hg). In Group II (n = 25), standard percutaneous coronary intervention without preconditioning was performed. We assessed endothelial function using the flow-mediated dilation test on baseline, then within 1-3 hours after percutaneous coronary intervention, and again on days 2 and 7 after percutaneous coronary intervention. The brachial artery flow-mediated dilation results were significantly higher on the first day after primary percutaneous coronary intervention in the preconditioning group (Group I) than in the control group (Group II) (12.1% vs 0.0%, P = .03, and 11.1% vs 6.3%, P = .016, respectively), and this difference remained on the seventh day (12.3% vs 7.4%, P = .0005, respectively). We demonstrated for the first time that remote ischemic preconditioning before primary percutaneous coronary intervention significantly improves endothelial function in patients with acute myocardial infarction, and this effect remains constant for at least a week. We suppose that the improvement of endothelial function may be one of the possible explanations of the effect of remote ischemic preconditioning. Copyright © 2014 Elsevier Inc. All rights reserved.

PRECONDITIONED CONJUGATE-GRADIENT 2 (PCG2), a computer program for solving ground-water flow equations

USGS Publications Warehouse

Hill, Mary C.

1990-01-01

This report documents PCG2 : a numerical code to be used with the U.S. Geological Survey modular three-dimensional, finite-difference, ground-water flow model . PCG2 uses the preconditioned conjugate-gradient method to solve the equations produced by the model for hydraulic head. Linear or nonlinear flow conditions may be simulated. PCG2 includes two reconditioning options : modified incomplete Cholesky preconditioning, which is efficient on scalar computers; and polynomial preconditioning, which requires less computer storage and, with modifications that depend on the computer used, is most efficient on vector computers . Convergence of the solver is determined using both head-change and residual criteria. Nonlinear problems are solved using Picard iterations. This documentation provides a description of the preconditioned conjugate gradient method and the two preconditioners, detailed instructions for linking PCG2 to the modular model, sample data inputs, a brief description of PCG2, and a FORTRAN listing.

Age-related reduction of cerebral ischemic preconditioning: myth or reality?

PubMed Central

Della-Morte, David; Cacciatore, Francesco; Salsano, Elisa; Pirozzi, Gilda; Genio, Maria Teresa Del; D’Antonio, Iole; Gargiulo, Gaetano; Palmirotta, Raffaele; Guadagni, Fiorella; Rundek, Tatjana; Abete, Pasquale

2013-01-01

Stroke is one of the leading causes of death in industrialized countries for people older than 65 years of age. The reasons are still unclear. A reduction of endogenous mechanisms against ischemic insults has been proposed to explain this phenomenon. The “cerebral” ischemic preconditioning mechanism is characterized by a brief episode of ischemia that renders the brain more resistant against subsequent longer ischemic events. This ischemic tolerance has been shown in numerous experimental models of cerebral ischemia. This protective mechanism seems to be reduced with aging both in experimental and clinical studies. Alterations of mediators released and/or intracellular pathways may be responsible for age-related ischemic preconditioning reduction. Agents able to mimic the “cerebral” preconditioning effect may represent a new powerful tool for the treatment of acute ischemic stroke in the elderly. In this article, animal and human cerebral ischemic preconditioning, its age-related difference, and its potential therapeutical applications are discussed. PMID:24204128

Preconditioned alternating direction method of multipliers for inverse problems with constraints

NASA Astrophysics Data System (ADS)

Jiao, Yuling; Jin, Qinian; Lu, Xiliang; Wang, Weijie

2017-02-01

We propose a preconditioned alternating direction method of multipliers (ADMM) to solve linear inverse problems in Hilbert spaces with constraints, where the feature of the sought solution under a linear transformation is captured by a possibly non-smooth convex function. During each iteration step, our method avoids solving large linear systems by choosing a suitable preconditioning operator. In case the data is given exactly, we prove the convergence of our preconditioned ADMM without assuming the existence of a Lagrange multiplier. In case the data is corrupted by noise, we propose a stopping rule using information on noise level and show that our preconditioned ADMM is a regularization method; we also propose a heuristic rule when the information on noise level is unavailable or unreliable and give its detailed analysis. Numerical examples are presented to test the performance of the proposed method.

Preconditioning for Numerical Simulation of Low Mach Number Three-Dimensional Viscous Turbomachinery Flows

NASA Technical Reports Server (NTRS)

Tweedt, Daniel L.; Chima, Rodrick V.; Turkel, Eli

1997-01-01

A preconditioning scheme has been implemented into a three-dimensional viscous computational fluid dynamics code for turbomachine blade rows. The preconditioning allows the code, originally developed for simulating compressible flow fields, to be applied to nearly-incompressible, low Mach number flows. A brief description is given of the compressible Navier-Stokes equations for a rotating coordinate system, along with the preconditioning method employed. Details about the conservative formulation of artificial dissipation are provided, and different artificial dissipation schemes are discussed and compared. The preconditioned code was applied to a well-documented case involving the NASA large low-speed centrifugal compressor for which detailed experimental data are available for comparison. Performance and flow field data are compared for the near-design operating point of the compressor, with generally good agreement between computation and experiment. Further, significant differences between computational results for the different numerical implementations, revealing different levels of solution accuracy, are discussed.

Rapamycin preconditioning attenuates transient focal cerebral ischemia/reperfusion injury in mice.

PubMed

Yin, Lele; Ye, Shasha; Chen, Zhen; Zeng, Yaoying

2012-12-01

Rapamycin, an mTOR inhibitor and immunosuppressive agent in clinic, has protective effects on traumatic brain injury and neurodegenerative diseases. But, its effects on transient focal ischemia/reperfusion disease are not very clear. In this study, we examined the effects of rapamycin preconditioning on mice treated with middle cerebral artery occlusion/reperfusion operation (MCAO/R). We found that the rapamycin preconditioning by intrahippocampal injection 20 hr before MCAO/R significantly improved the survival rate and longevity of mice. It also decreased the neurological deficit score, infracted areas and brain edema. In addition, rapamycin preconditioning decreased the production of NF-κB, TNF-α, and Bax, but not Bcl-2, an antiapoptotic protein in the ischemic area. From these results, we may conclude that rapamycin preconditioning attenuate transient focal cerebral ischemia/reperfusion injury and inhibits apoptosis induced by MCAO/R in mice.

A preconditioned formulation of the Cauchy-Riemann equations

NASA Technical Reports Server (NTRS)

Phillips, T. N.

1983-01-01

A preconditioning of the Cauchy-Riemann equations which results in a second-order system is described. This system is shown to have a unique solution if the boundary conditions are chosen carefully. This choice of boundary condition enables the solution of the first-order system to be retrieved. A numerical solution of the preconditioned equations is obtained by the multigrid method.

Preconditioning principles for preventing sports injuries in adolescents and children.

PubMed

Dollard, Mark D; Pontell, David; Hallivis, Robert

2006-01-01

Preseason preconditioning can be accomplished well over a 4-week period with a mandatory period of rest as we have discussed. Athletic participation must be guided by a gradual increase of skills performance in the child assessed after a responsible preconditioning program applying physiologic parameters as outlined. Clearly, designing a preconditioning program is a dynamic process when accounting for all the variables in training discussed so far. Despite the physiologic demands of sport and training, we still need to acknowledge the psychologic maturity and welfare of the child so as to ensure that the sport environment is a wholesome and emotionally rewarding experience.

Implementation of Preconditioned Dual-Time Procedures in OVERFLOW

NASA Technical Reports Server (NTRS)

Pandya, Shishir A.; Venkateswaran, Sankaran; Pulliam, Thomas H.; Kwak, Dochan (Technical Monitor)

2003-01-01

Preconditioning methods have become the method of choice for the solution of flowfields involving the simultaneous presence of low Mach and transonic regions. It is well known that these methods are important for insuring accurate numerical discretization as well as convergence efficiency over various operating conditions such as low Mach number, low Reynolds number and high Strouhal numbers. For unsteady problems, the preconditioning is introduced within a dual-time framework wherein the physical time-derivatives are used to march the unsteady equations and the preconditioned time-derivatives are used for purposes of numerical discretization and iterative solution. In this paper, we describe the implementation of the preconditioned dual-time methodology in the OVERFLOW code. To demonstrate the performance of the method, we employ both simple and practical unsteady flowfields, including vortex propagation in a low Mach number flow, flowfield of an impulsively started plate (Stokes' first problem) arid a cylindrical jet in a low Mach number crossflow with ground effect. All the results demonstrate that the preconditioning algorithm is responsible for improvements to both numerical accuracy and convergence efficiency and, thereby, enables low Mach number unsteady computations to be performed at a fraction of the cost of traditional time-marching methods.

Effects of exercise preconditioning on intestinal ischemia-reperfusion injury.

PubMed

Gokbel, H; Oz, M; Okudan, N; Belviranli, M; Esen, H

2014-01-01

To investigate the effects of exercise preconditioning on oxidative injury in the intestinal tissue of rats. Sixty male Wistar rats were randomly divided into six groups as sham (n = 10), ischemia-reperfusion (n = 10), exercise (n = 10), exercise plus ischemia-reperfusion (n = 10), ischemic preconditioning (n = 10), and ischemic preconditioning plus ischemia-reperfusion groups (n = 10). Tissue levels of malondialdehyde and activities of myeloperoxidase and superoxide dismutase, and serum levels of tumor necrosis factor-alpha and interleukin-6 were measured. Intestinal tissue histopathology was also evaluated by light microscopy. Tumor necrosis factor-alpha concentrations significantly decreased in the exercise group compared to the sham group (p < 0.05). Myeloperoxidase activity significantly increased and superoxide dismutase activity significantly decreased in ischemia-reperfusion group compared to the sham group (p < 0.05). Superoxide dismutase activity in the ischemic preconditioning and ischemic preconditioning plus ischemia-reperfusion groups were significantly higher compared to the ischemia-reperfusion and exercise groups (p < 0.05). Histopathologically, intestinal injury significantly attenuated in the exercise plus ischemia-reperfusion group compared to the ischemia-reperfusion group. The results of the present study indicate that exercise training seems to have a protective role against intestinal ischemia-reperfusion injury (Tab. 3, Fig. 1, Ref. 35).

Neuron specific metabolic adaptations following multi-day exposures to oxygen glucose deprivation.

PubMed

Zeiger, Stephanie L H; McKenzie, Jennifer R; Stankowski, Jeannette N; Martin, Jacob A; Cliffel, David E; McLaughlin, BethAnn

2010-11-01

Prior exposure to sub toxic insults can induce a powerful endogenous neuroprotective program known as ischemic preconditioning. Current models typically rely on a single stress episode to induce neuroprotection whereas the clinical reality is that patients may experience multiple transient ischemic attacks (TIAs) prior to suffering a stroke. We sought to develop a neuron-enriched preconditioning model using multiple oxygen glucose deprivation (OGD) episodes to assess the endogenous protective mechanisms neurons implement at the metabolic and cellular level. We found that neurons exposed to a five minute period of glucose deprivation recovered oxygen utilization and lactate production using novel microphysiometry techniques. Using the non-toxic and energetically favorable five minute exposure, we developed a preconditioning paradigm where neurons are exposed to this brief OGD for three consecutive days. These cells experienced a 45% greater survival following an otherwise lethal event and exhibited a longer lasting window of protection in comparison to our previous in vitro preconditioning model using a single stress. As in other models, preconditioned cells exhibited mild caspase activation, an increase in oxidized proteins and a requirement for reactive oxygen species for neuroprotection. Heat shock protein 70 was upregulated during preconditioning, yet the majority of this protein was released extracellularly. We believe coupling this neuron-enriched multi-day model with microphysiometry will allow us to assess neuronal specific real-time metabolic adaptations necessary for preconditioning. Copyright © 2010 Elsevier B.V. All rights reserved.

Preconditioning for the Navier-Stokes equations with finite-rate chemistry

NASA Technical Reports Server (NTRS)

Godfrey, Andrew G.

1993-01-01

The extension of Van Leer's preconditioning procedure to generalized finite-rate chemistry is discussed. Application to viscous flow is begun with the proper preconditioning matrix for the one-dimensional Navier-Stokes equations. Eigenvalue stiffness is resolved and convergence-rate acceleration is demonstrated over the entire Mach-number range from nearly stagnant flow to hypersonic. Specific benefits are realized at the low and transonic flow speeds typical of complete propulsion-system simulations. The extended preconditioning matrix necessarily accounts for both thermal and chemical nonequilibrium. Numerical analysis reveals the possible theoretical improvements from using a preconditioner for all Mach number regimes. Numerical results confirm the expectations from the numerical analysis. Representative test cases include flows with previously troublesome embedded high-condition-number areas. Van Leer, Lee, and Roe recently developed an optimal, analytic preconditioning technique to reduce eigenvalue stiffness over the full Mach-number range. By multiplying the flux-balance residual with the preconditioning matrix, the acoustic wave speeds are scaled so that all waves propagate at the same rate, an essential property to eliminate inherent eigenvalue stiffness. This session discusses a synthesis of the thermochemical nonequilibrium flux-splitting developed by Grossman and Cinnella and the characteristic wave preconditioning of Van Leer into a powerful tool for implicitly solving two and three-dimensional flows with generalized finite-rate chemistry. For finite-rate chemistry, the state vector of unknowns is variable in length. Therefore, the preconditioning matrix extended to generalized finite-rate chemistry must accommodate a flexible system of moving waves. Fortunately, no new kind of wave appears in the system. The only existing waves are entropy and vorticity waves, which move with the fluid, and acoustic waves, which propagate in Mach number dependent directions. The nonequilibrium vibrational energies and species densities in the unknown state vector act strictly as convective waves. The essential concept for extending the preconditioning to generalized chemistry models is determining the differential variables which symmetrize the flux Jacobians. The extension is then straight-forward. This algorithm research effort will be released in a future version of the production level computational code coined the General Aerodynamic Simulation Program (GASP), developed by Walters, Slack, and McGrory.

In vitro-microenvironment directs preconditioning of human chorion derived MSC promoting differentiation of OPC-like cells.

PubMed

Periasamy, Ramesh; Surbek, Daniel V; Schoeberlein, Andreina

2018-06-01

The loss of oligodendrocyte progenitor cells (OPC) is a hallmark of perinatal brain injury. Our aim was to develop an in vitro culture condition for human chorion-derived mesenchymal stem cells (MSC) that enhances their stem cell properties and their capability to differentiate towards OPC-like cells. MSC were grown either in serum replacement medium (SRM) or serum-containing medium (SM) and tested for their morphology, proliferation, secretome, migration, protein expression and differentiation into OPC-like cells. MSC cultured in SRM condition have distinct morphology/protein expression profile, increased cell proliferation/migration and capacity to differentiate into OPC-like cells. Copyright © 2018 Elsevier Ltd. All rights reserved.

An Extension of the Krieger-Li-Iafrate Approximation to the Optimized-Effective-Potential Method

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

Wilson, B.G.

1999-11-11

The Krieger-Li-Iafrate approximation can be expressed as the zeroth order result of an unstable iterative method for solving the integral equation form of the optimized-effective-potential method. By pre-conditioning the iterate a first order correction can be obtained which recovers the bulk of quantal oscillations missing in the zeroth order approximation. A comparison of calculated total energies are given with Krieger-Li-Iafrate, Local Density Functional, and Hyper-Hartree-Fock results for non-relativistic atoms and ions.

Preconditions needed for establishing a trusting relationship during health counselling - an interview study.

PubMed

Eriksson, Irene; Nilsson, Kerstin

2008-09-01

To examine the preconditions needed by district nurses to build a trusting relationship during health counselling of patients with hypertension. Trust has been found to be an important aspect of the patient-nurse relationship. Little research has focused on how trust is formed in patient-nurse relationships or the conditions the development process requires when working with health counselling; in particular not in relation to hypertension. Qualitative study. Qualitative data were collected through open-ended interviews with all (10) district nurses from three primary health care districts of western Sweden. All interviewees work with the health counselling of patients with hypertension. A latent content analysis was performed with thematic coding of the content of the interviews. The first theme that emerged from the analysis, the nurses' competence, describes the nurses' consciousness of their method of expression, both oral and non-verbal, as well as their pedagogical competence and their ability to be reliable in their profession. The second theme, the patient meeting, describes the continuity in the patient meeting and creating respectful communication. The results show an awareness of preconditions influencing building a trusting relationship. When creating a trusting relationship the communication and pedagogical competences of district nurses have considerable importance. Despite this awareness they state that it is easy to fall into a routinised way of working. The implications of this study might be used as support and guidance for district nurses when developing their competence in health counselling in relations to patients with hypertension. This knowledge is also important when planning for nurse-led clinics for this patient group.

The anti-apoptotic effect of fluid mechanics preconditioning by cells membrane and mitochondria in rats brain microvascular endothelial cells.

PubMed

Tian, Shan; Zhu, Fengping; Hu, Ruiping; Tian, Song; Chen, Xingxing; Lou, Dan; Cao, Bing; Chen, Qiulei; Li, Bai; Li, Fang; Bai, Yulong; Wu, Yi; Zhu, Yulian

2018-01-01

Exercise preconditioning is a simple and effective way to prevent ischemia. This paper further provided the mechanism in hemodynamic aspects at the cellular level. To study the anti-apoptotic effects of fluid mechanics preconditioning, Cultured rats brain microvascular endothelial cells were given fluid intervention in a parallel plate flow chamber before oxygen glucose deprivation. It showed that fluid mechanics preconditioning could inhibit the apoptosis of endothelial cells, and this process might be mediated by the shear stress activation of Tie-2 on cells membrane surface and Bcl-2 on the mitochondria surface. Copyright © 2017 Elsevier B.V. All rights reserved.

Involvement of Erythropoietin in Retinal Ischemic Preconditioning

PubMed Central

Dreixler, John C.; Hagevik, Sarah; Hemmert, Jonathan W.; Shaikh, Afzhal R.; Rosenbaum, Daniel M.; Roth, Steven

2009-01-01

Background The purpose of this study was to examine the role of erythropoietin in retinal ischemic preconditioning (IPC). Methods Rats were subjected to retinal ischemia after IPC. Electroretinography assessed functional recovery after ischemia; retinal sections were examined to determine loss of retinal ganglion cells, and Terminal Deoxynucleotidyl Transferase Mediated dUTP Nick End Labeling was used to assess apoptosis. Levels of downstream mediators were measured in retinal homogenates by Western blotting. To assess the involvement of erythropoietin in IPC, we measured levels of erythropoietin and its receptor (EPO-R) in retinal homogenates following IPC, using Western blotting. To examine erythropoietin’s role in IPC, we studied the impact of blocking erythropoietin via intravitreal injection of soluble EPO-R (sEPO-R) before IPC. Results Erythropoietin levels did not change following IPC, but EPO-R increased. Intravitreal injection of sEPO-R significantly attenuated both the functional and histological neuroprotection produced by IPC in comparison to control injection of denatured sEPO-R. Apoptotic damage after ischemia was enhanced in the sEPO-R treated retinas as indicated by fluorescent Terminal Deoxynucleotidyl Transferase Mediated dUTP Nick End Labeling. Phosphorylated extracellular-signal-regulated kinase (ERK) and heat shock protein 27 (Hsp27), but not protein kinase B (Akt), upregulated in denatured sEPO-R treated retinae, were attenuated in eyes injected with sEPO-R. Conclusions These results indicate that EPO-R upregulation is a critical component of the functional, histological, and anti-apoptotic protective effect of ischemic preconditioning on ischemia in the retina and that several downstream effectors may be involved in the neuroprotective actions of erythropoietin. PMID:19322943

Hepatic ischemia-reperfusion injury: roles of Ca2+ and other intracellular mediators of impaired bile flow and hepatocyte damage.

PubMed

Nieuwenhuijs, Vincent B; De Bruijn, Menno T; Padbury, Robert T A; Barritt, Gregory J

2006-06-01

Liver resection and liver transplantation have been successful in the treatment of liver tumors and end-stage liver disease. This success has led to an expansion in the pool of patients potentially treatable by liver surgery and, in the case of transplantation, to a shortage of liver donors. At present, there are significant numbers of potential candidates for liver resection and liver donation who have fatty livers, are aged, or have livers damaged by chemotherapy. All of these are at high risk for ischemic reperfusion (IR) injury. The aims of this review are to assess current knowledge of the clinical effectiveness of ischemic preconditioning and intermittent ischemia in reducing IR damage in liver surgery; to evaluate the use of bile flow as a sensitive indicator of IR liver damage; and to analyze the molecular mechanisms, especially intracellular Ca2+, involved in IR injury and ischemic preconditioning. It is concluded that bile flow is a sensitive indicator of IR injury. Together with reactive oxygen species (ROS) and other extracellular and intracellular signaling molecules, intracellular Ca2+ in hepatocytes plays a key role in the normal regulation of bile flow and in IR-induced injury and cell death. Ischemic preconditioning is an effective strategy to reduce IR injury but there is considerable scope for improvement, especially in patients with fatty and aged livers. The development of effective new strategies to reduce IR injury will depend on improved understanding of the molecular mechanisms involved, especially by gaining a better perspective of the relative importance of the various intrahepatocyte signaling pathways involved.

The effects of fetal and perinatal asphyxia on neuronal cytokine levels and ceramide metabolism in adulthood.

PubMed

Vlassaks, Evi; Gavilanes, Antonio W D; Vles, Johan S H; Deville, Sarah; Kramer, Boris W; Strackx, Eveline; Martinez-Martinez, Pilar

2013-02-15

In a rat model of global fetal and perinatal asphyxia, we investigated if asphyxia and long-lasting brain tolerance to asphyxia (preconditioning) are mediated by modifications in inflammatory cytokines and ceramide metabolism genes in prefrontal cortex, hippocampus and caudate-putamen at the age of 8months. Most significant changes were found in prefrontal cortex, with reduced LAG1 homolog ceramide synthase 1 expression after both types of asphyxia. Additionally, sphingosine kinase 1 was upregulated in those animals that experienced the combination of fetal and perinatal asphyxia (preconditioning), suggesting increased cell proliferation. While cytokine levels are normal, levels of ceramide genes were modulated both after fetal and perinatal asphyxia in the adult prefrontal cortex. Moreover, the combination of two subsequent asphyctic insults provides long-lasting neuroprotection in the prefrontal cortex probably by maintaining normal apoptosis and promoting cell proliferation. Better understanding of the effects of asphyxia on ceramide metabolism will help to understand the changes leading to brain tolerance and will open opportunities for the development of new neuroprotective therapies. Copyright © 2012 Elsevier B.V. All rights reserved.

Cardiovascular protection from alcoholic drinks: scientific basis of the French Paradox.

PubMed

Providência, Rui

2006-11-01

This article discusses the cardiovascular protection afforded by low to moderate consumption of ethanol and the role of ethanol-induced preconditioning. Ethanol, a compound that is found in many popular beverages, has a whole range of cardiovascular protective effects when consumed in low to moderate doses. Although they have yet to be totally clarified, recent data suggest that a combination of several actions at the biochemical and molecular levels play a role in this protection. These include favorable changes in lipid metabolism, antioxidant effects, changes in hemostasis and platelet aggregation, arterial vasodilation mediated by NO release, induction of the expression of cardioprotective proteins, insulin sensitization and lower levels of inflammatory markers. Special emphasis will be given to ethanol-induced preconditioning. Some of the compounds present in red and white wine, such as resveratrol and quercetin, are also partly responsible for some of the cardioprotective effects of alcoholic drinks. These are due to antioxidant effects and changes in platelet aggregation, endothelial function and inflammatory response. The last part of the paper will focus on the clinical applications and possibilities raised by these new findings.

Role of ischaemic preconditioning in liver regeneration following major liver resection and transplantation

PubMed Central

Gomez, D; Homer-Vanniasinkam, S; Graham, AM; Prasad, KR

2007-01-01

Liver ischaemic preconditioning (IPC) is known to protect the liver from the detrimental effects of ischaemic-reperfusion injury (IRI), which contributes significantly to the morbidity and mortality following major liver surgery. Recent studies have focused on the role of IPC in liver regeneration, the precise mechanism of which are not completely understood. This review discusses the current understanding of the mechanism of liver regeneration and the role of IPC in this setting. Relevant articles were reviewed from the published literature using the Medline database. The search was performed using the keywords “liver”, “ischaemic reperfusion”, “ischaemic preconditioning”, “regeneration”, “hepatectomy” and “transplantation”. The underlying mechanism of liver regeneration is a complex process involving the interaction of cytokines, growth factors and the metabolic demand of the liver. IPC, through various mediators, promotes liver regeneration by up-regulating growth-promoting factors and suppresses growth-inhibiting factors as well as damaging stresses. The increased understanding of the cellular mechanisms involved in IPC will enable the development of alternative treatment modalities aimed at promoting liver regeneration following major liver resection and transplantation. PMID:17278187

Fetal asphyxia induces acute and persisting changes in the ceramide metabolism in rat brain[S

PubMed Central

Vlassaks, Evi; Mencarelli, Chiara; Nikiforou, Maria; Strackx, Eveline; Ferraz, Maria J.; Aerts, Johannes M.; De Baets, Marc H.; Martinez-Martinez, Pilar; Gavilanes, Antonio W. D.

2013-01-01

Fetal asphyctic preconditioning, induced by a brief episode of experimental hypoxia-ischemia, offers neuroprotection to a subsequent more severe asphyctic insult at birth. Extensive cell stress and apoptosis are important contributing factors of damage in the asphyctic neonatal brain. Because ceramide acts as a second messenger for multiple apoptotic stimuli, including hypoxia/ischemia, we sought to investigate the possible involvement of the ceramide pathway in endogenous neuroprotection induced by fetal asphyctic preconditioning. Global fetal asphyxia was induced in rats by clamping both uterine and ovarian vasculature for 30 min. Fetal asphyxia resulted in acute changes in brain ceramide/sphingomyelin metabolic enzymes, ceramide synthase 1, 2, and 5, acid sphingomyelinase, sphingosine-1-phosphate phosphatase, and the ceramide transporter. This observation correlated with an increase in neuronal apoptosis and in astrocyte number. After birth, ceramide and sphingomyelin levels remained high in fetal asphyxia brains, suggesting that a long-term regulation of the ceramide pathway may be involved in the mechanism of tolerance to a subsequent, otherwise lethal, asphyctic event. PMID:23625371

The molecular mechanism underlying the proliferating and preconditioning effect of vitamin C on adipose-derived stem cells.

PubMed

Kim, Ji Hye; Kim, Wang-Kyun; Sung, Young Kwan; Kwack, Mi Hee; Song, Seung Yong; Choi, Joon-Seok; Park, Sang Gyu; Yi, TacGhee; Lee, Hyun-Joo; Kim, Dae-Duk; Seo, Hyun Min; Song, Sun U; Sung, Jong-Hyuk

2014-06-15

Although adipose-derived stem cells (ASCs) show promise for cell therapy, there is a tremendous need for developing ASC activators. In the present study, we investigated whether or not vitamin C increases the survival, proliferation, and hair-regenerative potential of ASCs. In addition, we tried to find the molecular mechanisms underlying the vitamin C-mediated stimulation of ASCs. Sodium-dependent vitamin C transporter 2 (SVCT2) is expressed in ASCs, and mediates uptake of vitamin C into ASCs. Vitamin C increased the survival and proliferation of ASCs in a dose-dependent manner. Vitamin C increased ERK1/2 phosphorylation, and inhibition of the mitogen-activated protein kinase (MAPK) pathway attenuated the proliferation of ASCs. Microarray and quantitative polymerase chain reaction showed that vitamin C primarily upregulated expression of proliferation-related genes, including Fos, E2F2, Ier2, Mybl1, Cdc45, JunB, FosB, and Cdca5, whereas Fos knock-down using siRNA significantly decreased vitamin C-mediated ASC proliferation. In addition, vitamin C-treated ASCs accelerated the telogen-to-anagen transition in C3H/HeN mice, and conditioned medium from vitamin C-treated ASCs increased the hair length and the Ki67-positive matrix keratinocytes in hair organ culture. Vitamin C increased the mRNA expression of HGF, IGFBP6, VEGF, bFGF, and KGF, which may mediate hair growth promotion. In summary, vitamin C is transported via SVCT2, and increased ASC proliferation is mediated by the MAPK pathway. In addition, vitamin C preconditioning enhanced the hair growth promoting effect of ASCs. Because vitamin C is safe and effective, it could be used to increase the yield and regenerative potential of ASCs.

The U.S. Geological Survey Modular Ground-Water Model - PCGN: A Preconditioned Conjugate Gradient Solver with Improved Nonlinear Control

USGS Publications Warehouse

Naff, Richard L.; Banta, Edward R.

2008-01-01

The preconditioned conjugate gradient with improved nonlinear control (PCGN) package provides addi-tional means by which the solution of nonlinear ground-water flow problems can be controlled as compared to existing solver packages for MODFLOW. Picard iteration is used to solve nonlinear ground-water flow equations by iteratively solving a linear approximation of the nonlinear equations. The linear solution is provided by means of the preconditioned conjugate gradient algorithm where preconditioning is provided by the modi-fied incomplete Cholesky algorithm. The incomplete Cholesky scheme incorporates two levels of fill, 0 and 1, in which the pivots can be modified so that the row sums of the preconditioning matrix and the original matrix are approximately equal. A relaxation factor is used to implement the modified pivots, which determines the degree of modification allowed. The effects of fill level and degree of pivot modification are briefly explored by means of a synthetic, heterogeneous finite-difference matrix; results are reported in the final section of this report. The preconditioned conjugate gradient method is coupled with Picard iteration so as to efficiently solve the nonlinear equations associated with many ground-water flow problems. The description of this coupling of the linear solver with Picard iteration is a primary concern of this document.

Integrity of Cerebellar Fastigial Nucleus Intrinsic Neurons Is Critical for the Global Ischemic Preconditioning

PubMed Central

Regnier-Golanov, Angelique S.; Britz, Gavin W.

2017-01-01

Excitation of intrinsic neurons of cerebellar fastigial nucleus (FN) renders brain tolerant to local and global ischemia. This effect reaches a maximum 72 h after the stimulation and lasts over 10 days. Comparable neuroprotection is observed following sublethal global brain ischemia, a phenomenon known as preconditioning. We hypothesized that FN may participate in the mechanisms of ischemic preconditioning as a part of the intrinsic neuroprotective mechanism. To explore potential significance of FN neurons in brain ischemic tolerance we lesioned intrinsic FN neurons with excitotoxin ibotenic acid five days before exposure to 20 min four-vessel occlusion (4-VO) global ischemia while analyzing neuronal damage in Cornu Ammoni area 1 (CA1) hippocampal area one week later. In FN-lesioned animals, loss of CA1 cells was higher by 22% compared to control (phosphate buffered saline (PBS)-injected) animals. Moreover, lesion of FN neurons increased morbidity following global ischemia by 50%. Ablation of FN neurons also reversed salvaging effects of five-minute ischemic preconditioning on CA1 neurons and morbidity, while ablation of cerebellar dentate nucleus neurons did not change effect of ischemic preconditioning. We conclude that FN is an important part of intrinsic neuroprotective system, which participates in ischemic preconditioning and may participate in naturally occurring neuroprotection, such as “diving response”. PMID:28934119

Super-low dose endotoxin pre-conditioning exacerbates sepsis mortality.

PubMed

Chen, Keqiang; Geng, Shuo; Yuan, Ruoxi; Diao, Na; Upchurch, Zachary; Li, Liwu

2015-04-01

Sepsis mortality varies dramatically in individuals of variable immune conditions, with poorly defined mechanisms. This phenomenon complements the hypothesis that innate immunity may adopt rudimentary memory, as demonstrated in vitro with endotoxin priming and tolerance in cultured monocytes. However, previous in vivo studies only examined the protective effect of endotoxin tolerance in the context of sepsis. In sharp contrast, we report herein that pre-conditionings with super-low or low dose endotoxin lipopolysaccharide (LPS) cause strikingly opposite survival outcomes. Mice pre-conditioned with super-low dose LPS experienced severe tissue damage, inflammation, increased bacterial load in circulation, and elevated mortality when they were subjected to cecal-ligation and puncture (CLP). This is in opposite to the well-reported protective phenomenon with CLP mice pre-conditioned with low dose LPS. Mechanistically, we demonstrated that super-low and low dose LPS differentially modulate the formation of neutrophil extracellular trap (NET) in neutrophils. Instead of increased ERK activation and NET formation in neutrophils pre-conditioned with low dose LPS, we observed significantly reduced ERK activation and compromised NET generation in neutrophils pre-conditioned with super-low dose LPS. Collectively, our findings reveal a novel mechanism potentially responsible for the dynamic programming of innate immunity in vivo as it relates to sepsis risks.

Mitogen Activated Protein Kinase Phosphatase-1 (MKP-1) in Retinal Ischemic Preconditioning

PubMed Central

Dreixler, John C.; Bratton, Anthony; Du, Eugenie; Shaikh, Afzhal R.; Savoie, Brian; Michael, Alexander; Marcet, Marcus; Roth, Steven

2011-01-01

We previously described the phenomenon of retinal ischemic preconditioning (IPC) and we have shown the role of various signaling proteins in the protective pathways, including the mitogen-activated protein kinase p38. In this study we examined the role in IPC of mitogen-activated protein kinase phosphatase-1 (MKP-1), which inactivates p38. Ischemia was produced by elevation of intraocular pressure above systolic arterial blood pressure in adult Wistar rats. Preconditioning was produced by transient retinal ischemia for 5 min, 24 h prior to ischemia. Small interfering RNA (siRNA) to MKP-1 or a control non-silencing siRNA, was injected into the vitreous 6 h prior to IPC. Recovery was assessed by electroretinography (ERG) and histology. The a- and b-waves, and oscillatory potentials (OPs), measured before and 1 week after ischemia, were then normalized relative to pre-ischemic baseline, and corrected for diurnal variation in the normal non-ischemic eye. The P2, or post-photoreceptor component of the ERG (which reflects function of the rod bipolar cells in the inner retina), was derived using the Hood-Birch model. MKP-1 was localized in specific retinal cells using immunohistochemistry; levels of mitogen-activated protein kinases were measured using Western blotting. Injection of siRNA to MKP-1 significantly attenuated the protective effect of IPC as reflected by decreased recovery of the electroretinogram a- and b-waves and the P2 after ischemia. The injection of siRNA to MKP-1 reduced the number of cells in the retinal ganglion cell and outer nuclear layers after IPC and ischemia. Blockade of MKP-1 by siRNA also increased the activation of p38 at 24 h following IPC. MKP-1 siRNA did not alter the levels of phosphorylated jun N-terminal kinase (JNK) or extracellular signal-regulated kinase (ERK) after IPC. The results suggest the involvement of dual-specificity phosphatase MKP-1 in IPC and that MKP-1 is involved in IPC by regulating levels of activated MAPK p38. PMID:21094639

The role of 17-beta estradiol in ischemic preconditioning protection of the heart.

PubMed

Babiker, Fawzi A; Hoteit, Lamia J; Joseph, Shaji; Mustafa, Abu Salim; Juggi, Jasbir S

2012-09-01

The protective effects of 17-beta estradiol (E2) on cardiac tissue during ischemia/reperfusion (I/R) injury have not yet been fully elucidated. To assess the protective effects of short- and long-term E2 treatments on cardiac tissue exposed to I/R, and to assess the effects of these treatments in combination with ischemic preconditioning (IPC) on cardiac protection from I/R injury. SPRAGUE DAWLEY RATS WERE ASSIGNED TO THE FOLLOWING TREATMENT PROTOCOLS: control (no preconditioning); IPC (isolated hearts were subjected to two cycles of 5 min global ischemia followed by 10 min of reperfusion); E2 preconditioning (E2PC; isolated hearts were subjected to E2 pharmacological perfusion for 15 min); short-term in vivo E2 pretreatment for 3 h; long-term in vivo E2 pretreatment or withdrawal (ovariectomy followed by a six-week treatment with E2 or a placebo); combined IPC and E2PC; combined IPC and short- or long-term E2 pretreatments or withdrawal. All hearts were isolated and stabilized for at least 30 min before being subjected to 40 min of global ischemia followed by 30 min of reperfusion; left ventricular function and vascular hemodynamics were then assessed. IPC, E2PC and short-term E2 pretreatment led to the recovery of left ventricle function and vascular hemodynamics. Long-term E2 and placebo treatments did not result in any protection compared with untreated controls. The combination of E2PC or short-term E2 treatments with IPC did not block the IPC protection or result in any additional protection to the heart. Long-term E2 treatment blocked IPC protection; however, placebo treatment did not. Short-term treatment with E2 protected the heart against I/R injury through a pathway involving the regulation of tumour necrosis factor-alpha. The combination of short-term E2 treatment with IPC did not provide additional protection to the heart. Short-term E2 treatment may be a suitable alternative for classical estrogen replacement therapy.

"Managed competition" for Ireland? The single versus multiple payer debate.

PubMed

Mikkers, Misja; Ryan, Padhraig

2014-09-26

A persistent feature of international health policy debate is whether a single-payer or multiple-payer system can offer superior performance. In Ireland, a major reform proposal is the introduction of 'managed competition' based on the recent reforms in the Netherlands, which would replace many functions of Ireland's public payer with a system of competing health insurers from 2016. This article debates whether Ireland meets the preconditions for effective managed competition, and whether the government should implement the reform according to its stated timeline. We support our arguments by discussing the functioning of the Dutch and Irish systems. Although Ireland currently lacks key preconditions for effective implementation, the Dutch experience demonstrates that some of these can be implemented over time, such as a more rigorous risk equalization system. A fundamental problem may be Ireland's sparse hospital distribution. This may increase the market power of hospitals and weaken insurers' ability to exclude inefficient or poor quality hospitals from contracts, leading to unwarranted spending growth. To mitigate this, the government proposes to introduce a system of price caps for hospital services.The Dutch system of competition is still in transition and it is premature to judge its success. The new system may have catalyzed increased transparency regarding clinical performance, but outcome measurement remains crude. A multi-payer environment creates some disincentives for quality improvement, one of which is free-riding by insurers on their rivals' quality investments. If a Dutch insurer invests in improving hospital quality, hospitals will probably offer equivalent quality to consumers enrolled with other insurance companies. This enhances equity, but may weaken incentives for improvement. Consequently the Irish government, rather than insurers, may need to assume responsibility for investing in clinical quality. Plans are in place to assure consumers of free choice of insurer, but a key concern is a potential shortfall of institutional capacity to regulate managed competition. Managed competition requires a long transition period and the requisite preconditions are not yet in place. The Irish government should refrain from introducing managed competition until sufficient preconditions are in place to allow effective performance.

The mitochondria-targeted antioxidants and remote kidney preconditioning ameliorate brain damage through kidney-to-brain cross-talk.

PubMed

Silachev, Denis N; Isaev, Nikolay K; Pevzner, Irina B; Zorova, Ljubava D; Stelmashook, Elena V; Novikova, Svetlana V; Plotnikov, Egor Y; Skulachev, Vladimir P; Zorov, Dmitry B

2012-01-01

Many ischemia-induced neurological pathologies including stroke are associated with high oxidative stress. Mitochondria-targeted antioxidants could rescue the ischemic organ by providing specific delivery of antioxidant molecules to the mitochondrion, which potentially suffers from oxidative stress more than non-mitochondrial cellular compartments. Besides direct antioxidative activity, these compounds are believed to activate numerous protective pathways. Endogenous anti-ischemic defense may involve the very powerful neuroprotective agent erythropoietin, which is mainly produced by the kidney in a redox-dependent manner, indicating an important role of the kidney in regulation of brain ischemic damage. The goal of this study is to track the relations between the kidney and the brain in terms of the amplification of defense mechanisms during SkQR1 treatment and remote renal preconditioning and provide evidence that the kidney can generate signals inducing a tolerance to oxidative stress-associated brain pathologies. We used the cationic plastoquinone derivative, SkQR1, as a mitochondria-targeted antioxidant to alleviate the deleterious consequences of stroke. A single injection of SkQR1 before cerebral ischemia in a dose-dependent manner reduces infarction and improves functional recovery. Concomitantly, an increase in the levels of erythropoietin in urine and phosphorylated glycogen synthase kinase-3β (GSK-3β) in the brain was detected 24 h after SkQR1 injection. However, protective effects of SkQR1 were not observed in rats with bilateral nephrectomy and in those treated with the nephrotoxic antibiotic gentamicin, indicating the protective role of humoral factor(s) which are released from functional kidneys. Renal preconditioning also induced brain protection in rats accompanied by an increased erythropoietin level in urine and kidney tissue and P-GSK-3β in brain. Co-cultivation of SkQR1-treated kidney cells with cortical neurons resulted in enchanced phosphorylation of GSK-3β in neuronal cells. The results indicate that renal preconditioning and SkQR1-induced brain protection may be mediated through the release of EPO from the kidney.

Thyroid hormone activates rat liver adenosine 5,-monophosphate-activated protein kinase: relation to CaMKKb, TAK1 and LKB1 expression and energy status.

PubMed

Vargas, R; Ortega, Y; Bozo, V; Andrade, M; Minuzzi, G; Cornejo, P; Fernandez, V; Videla, L A

2013-01-01

AMP-activated protein kinase (AMPK) is a sensor of energy status supporting cellular energy homeostasis that may represent the metabolic basis for 3,3,,5-triiodo-L-thyronine (T3) liver preconditioning. Functionally transient hyperthyroid state induced by T3 (single dose of 0.1 mg/kg) in fed rats led to upregulation of mRNA expression (RT-PCR) and protein phosphorylation (Western blot) of hepatic AMPK at 8 to 36 h after treatment. AMPK Thr 172 phosphorylation induced by T3 is associated with enhanced mRNA expression of the upstream kinases Ca2+ -calmodulin-dependent protein kinase kinase-beta (CaMKKbeta) and transforming growth-factor-beta-activated kinase-1 (TAK1), with increased protein levels of CaMKKbeta and higher TAK1 phosphorylation, without changes in those of the liver kinase B1 (LKB1) signaling pathway. Liver contents of AMP and ADP were augmented by 291 percent and 44 percent by T3 compared to control values (p less than 0.05), respectively, whereas those of ATP decreased by 64% (p less than 0.05), with no significant changes in the total content of adenine nucleotides (AMP + ADP + ATP) at 24 h after T3 administration. Consequently, hepatic ATP/ADP content ratios exhibited 64 percent diminution (p less than 0.05) and those of AMP/ATP increased by 425 percent (p less than 0.05) in T3-treated rats over controls. It is concluded that in vivoT3 administration triggers liver AMPK upregulation in association with significant enhancements in AMPK mRNA expression, AMPK phosphorylation coupled to CaMKKbeta and TAK1 activation, and in AMP/ATP ratios, which may promote enhanced AMPK activity to support T3-induced energy consuming processes such as those of liver preconditioning.

Incomplete Sparse Approximate Inverses for Parallel Preconditioning

DOE PAGES

Anzt, Hartwig; Huckle, Thomas K.; Bräckle, Jürgen; ...

2017-10-28

In this study, we propose a new preconditioning method that can be seen as a generalization of block-Jacobi methods, or as a simplification of the sparse approximate inverse (SAI) preconditioners. The “Incomplete Sparse Approximate Inverses” (ISAI) is in particular efficient in the solution of sparse triangular linear systems of equations. Those arise, for example, in the context of incomplete factorization preconditioning. ISAI preconditioners can be generated via an algorithm providing fine-grained parallelism, which makes them attractive for hardware with a high concurrency level. Finally, in a study covering a large number of matrices, we identify the ISAI preconditioner as anmore » attractive alternative to exact triangular solves in the context of incomplete factorization preconditioning.« less

Preconditioning for the Navier-Stokes equations with finite-rate chemistry

NASA Technical Reports Server (NTRS)

Godfrey, Andrew G.; Walters, Robert W.; Van Leer, Bram

1993-01-01

The preconditioning procedure for generalized finite-rate chemistry and the proper preconditioning for the one-dimensional Navier-Stokes equations are presented. Eigenvalue stiffness is resolved and convergence-rate acceleration is demonstrated over the entire Mach-number range from the incompressible to the hypersonic. Specific benefits are realized at low and transonic flow speeds. The extended preconditioning matrix accounts for thermal and chemical non-equilibrium and its implementation is explained for both explicit and implicit time marching. The effect of higher-order spatial accuracy and various flux splittings is investigated. Numerical analysis reveals the possible theoretical improvements from using proconditioning at all Mach numbers. Numerical results confirm the expectations from the numerical analysis. Representative test cases include flows with previously troublesome embedded high-condition-number regions.

Prospects for regulated competition in the health care system: what can China learn from Russia's experience?

PubMed

Xu, Weiwei; Sheiman, Igor; van de Ven, Wynand P M M; Zhang, Wei

2011-05-01

As China explores new directions to reform its health care system, regulated competition among both insurers and providers of care might be one potential model. The Russian Federation in 1993 implemented legislation intended to stimulate such regulated competition in the health care sector. The subsequent progress and lessons learned over these 17 years can shed light on and inform the future evolution of the Chinese system. In this paper, we list the necessary pre-conditions for reaping the benefits of regulated competition in the health care sector. We indicate to what extent these conditions are being fulfilled in the post-reform Russian and current Chinese health care systems. We draw lessons from the Russian experience for the Chinese health care system, which shares a similar economic and political background with the pre-reform Russian health care system in terms of the starting point of the reform, and analyse the prospects for regulated competition in China.

Remote limb ischemic preconditioning (rIPC) activates antioxidant and antiapoptotic genes and inhibits proinflammatory cytokine genes in renal ischemia/reperfusion injury.

PubMed

Hussein, Abdelaziz M; Harraz, Ahmed M; Awadalla, Amira; Barakat, Nashwa; Khater, Shery; Shokeir, Ahmed A

2016-01-01

The mechanisms underlying the renoprotective effect for remote limb ischemic preconditioning (rIPC) against renal ischemia/reperfusion injury need further elucidation. In our work, one hundred and twenty male Sprague Dawley rats were randomized into 3 groups; sham, I/R group (left renal 45 min ischemia) and rIPC (as I/R group with 3 cycles of left femoral ischemic PC just before renal ischemia). Rats were sacrificed at 2 h, 24 h, 48 h and 7 days. Serum creatinine and urea were measured at the baseline and endpoints. Also, histopathological examination and assessment of the expression of inflammatory cytokines e.g. TNF-α, IL-1β and ICAM-1 and antioxidant genes: Nrf2, HO-1 and NQO-1 and anti-apoptotic gene Bcl-2 in left kidney were done by the end of experiment. The results of this study demonstrated that, rIPC caused significant improvement in serum creatinine and BUN levels and in the expression of antioxidant genes and Bcl-2 antiapoptotic gene with significant attenuation of pro-inflammatory cytokines and histopathological damage score at all-time points compared to I/R group (p ≤ 0.05). In conclusion, inhibition of inflammatory cytokine (TNF-α, IL-1β and ICAM-1) formation and activation of antioxidant genes: Nrf2, HO-1 and NQO-1 and anti-apoptotic gene Bcl-2 could be possible underlying mechanisms for the renoprotective effect of rIPC.

[Does co-operation research provide approaches to explain the changes in the German hospital market?].

PubMed

Raible, C; Leidl, R

2004-11-01

The German hospital market faces an extensive process of consolidation. In this change hospitals consider cooperation as one possibility to improve competitiveness. To investigate explanations of changes in the German hospital market by theoretical approaches of cooperation research. The aims and mechanism of the theories, their relevance in terms of contents and their potential for empirical tests were used as criteria to assess the approaches, with current and future trends in the German hospital market providing the framework. Based on literature review, six theoretical approaches were investigated: industrial organization, transaction cost theory, game theory, resource dependency, institutional theory, and co-operative investment and finance theory. In addition, the data needed to empirically test the theories were specified. As a general problem, some of the theoretical approaches set a perfect market as a precondition. This precondition is not met by the heavily regulated German hospital market. Given the current regulations and the assessment criteria, industrial organization as well as resource-dependency and institutional theory approaches showed the highest potential to explain various aspects of the changes in the hospital market. So far, none of the approaches investigated provides a comprehensive and empirically tested explanation of the changes in the German hospital market. However, some of the approaches provide a theoretical background for part of the changes. As this dynamic market is economically of high significance, there is a need for further development and empirical testing of relevant theoretical approaches.

Progressive thermopreconditioning attenuates rat cardiac ischemia/reperfusion injury by mitochondria-mediated antioxidant and antiapoptotic mechanisms.

PubMed

Chien, Chen-Yen; Chien, Chiang-Ting; Wang, Shoei-Shen

2014-08-01

Progressive thermal preconditioning (PTP) provides vascular protection with less hemodynamic fluctuations, endoplasmic reticulum (ER), and oxidative stress compared with whole body hyperthermia. We suggest PTP might efficiently diminish cardiac ischemia/reperfusion-induced apoptosis and autophagy injury. A total of 67 male Wistar rats were divided into a non-PTP control group, 24 or 72 hours after a single cycle or 3 consecutive cycles of PTP in a 42°C water bath (1-24, 1-72, 3-24, and 3-72 groups). We measured the cardiac O2(-) amount in vivo in response to left anterior descending coronary artery ligation for 2 hours and reperfusion for 3 hours. Cardiac function and injury were determined by microcirculation, electrocardiography, and infarct size. The PTP-induced protective effects on nicotinamide adenine dinucleotide phosphate oxidase gp91-mediated oxidative stress, ER stress, and apoptosis- and autophagy-related mechanisms were examined using Western blot and immunohistochemistry. Coronary arterial ischemia/reperfusion depressed cardiac microcirculation, induced ST-segment elevation and increased infarct size in non-PTP and PTP rats. Ischemia/reperfusion enhanced the cardiac O2(-) levels by enhanced nicotinamide adenine dinucleotide phosphate oxidase gp91 expression, cytosolic cytochrome C release, and decreased mitochondrial Bcl-2 expression. Cardiac injury activated ER stress-78-kDa glucose-regulated protein expression, increased the Bax/Bcl-2 ratio, cleaved caspase 3 expression and poly-(ADP-ribose)-polymerase fragments, leading to apoptosis formation, and promoted LC3-II expression, resulting in autophagy formation. PTP treatment elevated heat shock protein 70, heat shock protein 32, Bcl-2, Bcl-xL, and manganese superoxide dismutase in the rat heart, especially in the 3-72 group. PTP treatment significantly restored cardiac microcirculation, decreased oxidative stress, ER stress, apoptosis, autophagy, and infarct size. PTP significantly reduced cardiac ischemia/reperfusion injury by upregulating antioxidant, antiapoptotic, and antiautophagic mechanisms. Copyright © 2014 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

The involvement of protein kinase C-ε in isoflurane induced preconditioning of human embryonic stem cell--derived Nkx2.5(+) cardiac progenitor cells.

PubMed

Song, In-Ae; Oh, Ah-Young; Kim, Jin-Hee; Choi, Young-Min; Jeon, Young-Tae; Ryu, Jung-Hee; Hwang, Jung-Won

2016-02-20

Anesthetic preconditioning can improve survival of cardiac progenitor cells exposed to oxidative stress. We investigated the role of protein kinase C and isoform protein kinase C-ε in isoflurane-induced preconditioning of cardiac progenitor cells exposed to oxidative stress. Cardiac progenitor cells were obtained from undifferentiated human embryonic stem cells. Immunostaining with anti-Nkx2.5 was used to confirm the differentiated cardiac progenitor cells. Oxidative stress was induced by H2O2 and FeSO4. For anesthetic preconditioning, cardiac progenitor cells were exposed to 0.25, 0.5, and 1.0 mM of isoflurane. PMA and chelerythrine were used for protein kinase C activation and inhibition, while εψRACK and εV1-2 were used for protein kinase C -ε activation and inhibition, respectively. Isoflurane-preconditioning decreased the death rate of Cardiac progenitor cells exposed to oxidative stress (death rates isoflurane 0.5 mM 12.7 ± 9.3%, 1.0 mM 12.0 ± 7.7% vs. control 31.4 ± 10.2%). Inhibitors of both protein kinase C and protein kinase C -ε abolished the preconditioning effect of isoflurane 0.5 mM (death rates 27.6 ± 13.5% and 25.9 ± 8.7% respectively), and activators of both protein kinase C and protein kinase C - ε had protective effects from oxidative stress (death rates 16.0 ± 3.2% and 10.6 ± 3.8% respectively). Both PKC and PKC-ε are involved in isoflurane-induced preconditioning of human embryonic stem cells -derived Nkx2.5(+) Cardiac progenitor cells under oxidative stress.

Exercise preconditioning improves behavioral functions following transient cerebral ischemia induced by 4-vessel occlusion (4-VO) in rats.

PubMed

Tahamtan, Mahshid; Allahtavakoli, Mohammad; Abbasnejad, Mehdi; Roohbakhsh, Ali; Taghipour, Zahra; Taghavi, Mohsen; Khodadadi, Hassan; Shamsizadeh, Ali

2013-12-01

There is evidence that exercise decreases ischemia/reperfusion injury in rats. Since behavioral deficits are the main outcome in patients after stroke, our study was designed to investigate whether exercise preconditioning improves the acute behavioral functions and also brain inflammatory injury following cerebral ischemia. Male rats weighing 250-300 g were randomly allocated into five experimental groups. Exercise was performed on a treadmill 30min/day for 3 weeks. Ischemia was induced by 4-vessel occlusion method. Recognition memory was assessed by novel object recognition task (NORT) and step-through passive avoidance task. Sensorimotor function and motor movements were evaluated by adhesive removal test and ledged beam-walking test, respectively. Brain inflammatory injury was evaluated by histological assessment. In NORT, the discrimination ratio was decreased after ischemia (P < 0.05) and exercise preconditioning improved it in ischemic animals. In the passive avoidance test, a significant reduction in response latency was observed in the ischemic group. Exercise preconditioning significantly decreased the response latency in the ischemic rats (P < 0.001). In the adhesive removal test, latency to touch and remove the sticky labels from forepaw was increased following induction of ischemia (all P < 0.001) and exercise preconditioning decreased these indices compared to the ischemic group (all P < 0.001). In the ledged beam-walking test, the slip ratio was increased following ischemia (P < 0.05).  In the ischemia group, marked neuronal injury in hippocampus was observed. These neuropathological changes were attenuated by exercise preconditioning (P < 0.001). Our results showed that exercise preconditioning improves behavioral functions and maintains more viable cells in the dorsal hippocampus of the ischemic brain.

Mechanical preconditioning enables electrophysiologic coupling of skeletal myoblast cells to myocardium

PubMed Central

Treskes, Philipp; Cowan, Douglas B.; Stamm, Christof; Rubach, Martin; Adelmann, Roland; Wittwer, Thorsten; Wahlers, Thorsten

2015-01-01

Objective The effect of mechanical preconditioning on skeletal myoblasts in engineered tissue constructs was investigated to resolve issues associated with conduction block between skeletal myoblast cells and cardiomyocytes. Methods Murine skeletal myoblasts were used to generate engineered tissue constructs with or without application of mechanical strain. After in vitro myotube formation, engineered tissue constructs were co-cultured for 6 days with viable embryonic heart slices. With the use of sharp electrodes, electrical coupling between engineered tissue constructs and embryonic heart slices was assessed in the presence or absence of pharmacologic agents. Results The isolation and expansion procedure for skeletal myoblasts resulted in high yields of homogeneously desmin-positive (97.1% ± 0.1%) cells. Mechanical strain was exerted on myotubes within engineered tissue constructs during gelation of the matrix, generating preconditioned engineered tissue constructs. Electrical coupling between preconditioned engineered tissue constructs and embryonic heart slices was observed; however, no coupling was apparent when engineered tissue constructs were not subjected to mechanical strain. Coupling of cells from engineered tissue constructs to cells in embryonic heart slices showed slower conduction velocities than myocardial cells with the embryonic heart slices (preconditioned engineered tissue constructs vs embryonic heart slices: 0.04 ± 0.02 ms vs 0.10 ± 0.05 ms, P = .011), lower stimulation frequencies (preconditioned engineered tissue constructs vs maximum embryonic heart slices: 4.82 ± 1.42 Hz vs 10.58 ± 1.56 Hz; P = .0009), and higher sensitivities to the gap junction inhibitor (preconditioned engineered tissue constructs vs embryonic heart slices: 0.22 ± 0.07 mmol/L vs 0.93 ± 0.15 mmol/L; P = .0004). Conclusions We have generated skeletal myoblast–based transplantable grafts that electrically couple to myocardium. PMID:22980065

Cardioprotection of ischaemic preconditioning is associated with inhibition of translocation of MLKL within the plasma membrane.

PubMed

Szobi, Adrián; Farkašová-Ledvényiová, Veronika; Lichý, Martin; Muráriková, Martina; Čarnická, Slávka; Ravingerová, Tatiana; Adameová, Adriana

2018-06-19

Necroptosis, a form of cell loss involving the RIP1-RIP3-MLKL axis, has been identified in cardiac pathologies while its inhibition is cardioprotective. We investigated whether the improvement of heart function because of ischaemic preconditioning is associated with mitigation of necroptotic signaling, and these effects were compared with a pharmacological antinecroptotic approach targeting RIP1. Langendorff-perfused rat hearts were subjected to ischaemic preconditioning with or without a RIP1 inhibitor (Nec-1s). Necroptotic signaling and the assessment of oxidative damage and a putative involvement of CaMKII in this process were analysed in whole tissue and subcellular fractions. Ischaemic preconditioning, Nec-1s and their combination improved postischaemic heart function recovery and reduced infarct size to a similar degree what was in line with the prevention of MLKL oligomerization and translocation to the membrane. On the other hand, membrane peroxidation and apoptosis were unchanged by either approach. Ischaemic preconditioning failed to ameliorate ischaemia-reperfusion-induced increase in RIP1 and RIP3 while pSer229-RIP3 levels were reduced only by Nec-1s. In spite of the additive phosphorylation of CaMKII and PLN because of ditherapy, the postischaemic contractile force and relaxation was comparably improved in all the intervention groups while antiarrhythmic effects were observed in the ischaemic preconditioning group only. Necroptosis inhibition seems to be involved in cardioprotection of ischaemic preconditioning and is comparable but not intensified by an anti-RIP1 agent. Changes in oxidative stress nor CaMKII signaling are unlikely to explain the beneficial effects. © 2018 Comenius University in Bratislava, Faculty of Pharmacy. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

Effect of non-invasive remote ischemic preconditioning on intra-renal perfusion in volunteers.

PubMed

Robert, René; Vinet, Mathieu; Jamet, Angéline; Coudroy, Rémi

2017-06-01

Remote ischemic preconditioning may attenuate renal injury and protect the kidney during subsequent inflammatory or ischemic stress. However, the mechanism of such a protection is not well understood. The aim of this study was to investigate the impact of remote ischemic preconditioning on renal resistivity index (RRI) in nine healthy volunteers. In six volunteers, four cycles of 4-min inflation of a blood pressure cuff were applied to one upper arm, followed by 4-min reperfusion with the cuff deflated. RRI was determined using Doppler echography during each cuff deflated period. Measures were also performed in three volunteers without preconditioning. The median value of RRI significantly decreased progressively from 0.59 [0.53-0.62] before the remote conditioning (baseline) to 0.49 [0.46-0.53] at the end of the experiment (p < 0.001) whereas there was no change in controls. In this study, for the first time, we have clearly shown in a small group of subjects that remote ischemic preconditioning can induce a significantly decrease in RRI through increased intra-renal perfusion.

Teko: A block preconditioning capability with concrete example applications in Navier--Stokes and MHD

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

Cyr, Eric C.; Shadid, John N.; Tuminaro, Raymond S.

This study describes the design of Teko, an object-oriented C++ library for implementing advanced block preconditioners. Mathematical design criteria that elucidate the needs of block preconditioning libraries and techniques are explained and shown to motivate the structure of Teko. For instance, a principal design choice was for Teko to strongly reflect the mathematical statement of the preconditioners to reduce development burden and permit focus on the numerics. Additional mechanisms are explained that provide a pathway to developing an optimized production capable block preconditioning capability with Teko. Finally, Teko is demonstrated on fluid flow and magnetohydrodynamics applications. In addition to highlightingmore » the features of the Teko library, these new results illustrate the effectiveness of recent preconditioning developments applied to advanced discretization approaches.« less

Teko: A block preconditioning capability with concrete example applications in Navier--Stokes and MHD

DOE PAGES

Cyr, Eric C.; Shadid, John N.; Tuminaro, Raymond S.

2016-10-27

This study describes the design of Teko, an object-oriented C++ library for implementing advanced block preconditioners. Mathematical design criteria that elucidate the needs of block preconditioning libraries and techniques are explained and shown to motivate the structure of Teko. For instance, a principal design choice was for Teko to strongly reflect the mathematical statement of the preconditioners to reduce development burden and permit focus on the numerics. Additional mechanisms are explained that provide a pathway to developing an optimized production capable block preconditioning capability with Teko. Finally, Teko is demonstrated on fluid flow and magnetohydrodynamics applications. In addition to highlightingmore » the features of the Teko library, these new results illustrate the effectiveness of recent preconditioning developments applied to advanced discretization approaches.« less

Elasmobranch qPCR reference genes: a case study of hypoxia preconditioned epaulette sharks

PubMed Central

2010-01-01

Background Elasmobranch fishes are an ancient group of vertebrates which have high potential as model species for research into evolutionary physiology and genomics. However, no comparative studies have established suitable reference genes for quantitative PCR (qPCR) in elasmobranchs for any physiological conditions. Oxygen availability has been a major force shaping the physiological evolution of vertebrates, especially fishes. Here we examined the suitability of 9 reference candidates from various functional categories after a single hypoxic insult or after hypoxia preconditioning in epaulette shark (Hemiscyllium ocellatum). Results Epaulette sharks were caught and exposed to hypoxia. Tissues were collected from 10 controls, 10 individuals with single hypoxic insult and 10 individuals with hypoxia preconditioning (8 hypoxic insults, 12 hours apart). We produced sequence information for reference gene candidates and monitored mRNA expression levels in four tissues: cerebellum, heart, gill and eye. The stability of the genes was examined with analysis of variance, geNorm and NormFinder. The best ranking genes in our study were eukaryotic translation elongation factor 1 beta (eef1b), ubiquitin (ubq) and polymerase (RNA) II (DNA directed) polypeptide F (polr2f). The performance of the ribosomal protein L6 (rpl6) was tissue-dependent. Notably, in one tissue the analysis of variance indicated statistically significant differences between treatments for genes that were ranked as the most stable candidates by reference gene software. Conclusions Our results indicate that eef1b and ubq are generally the most suitable reference genes for the conditions and tissues in the present epaulette shark studies. These genes could also be potential reference gene candidates for other physiological studies examining stress in elasmobranchs. The results emphasise the importance of inter-group variation in reference gene evaluation. PMID:20416043

An overview of protective strategies against ischemia/reperfusion injury: The role of hyperbaric oxygen preconditioning.

PubMed

Hentia, Ciprian; Rizzato, Alex; Camporesi, Enrico; Yang, Zhongjin; Muntean, Danina M; Săndesc, Dorel; Bosco, Gerardo

2018-05-01

Ischemia/reperfusion (I/R) injury, such as myocardial infarction, stroke, and peripheral vascular disease, has been recognized as the most frequent causes of devastating disorders and death currently. Protective effect of various preconditioning stimuli, including hyperbaric oxygen (HBO), has been proposed in the management of I/R. In this study, we searched and reviewed up-to-date published papers to explore the pathophysiology of I/R injury and to understand the mechanisms underlying the protective effect of HBO as conditioning strategy. Animal study and clinic observation support the notion that HBO therapy and conditioning provide beneficial effect against the deleterious effects of postischemic reperfusion. Several explanations have been proposed. The first likely mechanism may be that HBO counteracts hypoxia and reduces I/R injury by improving oxygen delivery to an area with diminished blood flow. Secondly, by reducing hypoxia-ischemia, HBO reduces all the pathological events as a consequence of hypoxia, including tissue edema, increased affective area permeability, postischemia derangement of tissue metabolism, and inflammation. Thirdly, HBO may directly affect cell apoptosis, signal transduction, and gene expression in those that are sensitive to oxygen or hypoxia. HBO provides a reservoir of oxygen at cellular level not only carried by blood, but also by diffusion from the interstitial tissue where it reaches high concentration that may last for several hours, improves endothelial function and rheology, and decreases local inflammation and edema. Evidence suggests the benefits of HBO when used as a preconditioning stimulus in the setting of I/R injury. Translating the beneficial effects of HBO into current practice requires, as for the "conditioning strategies", a thorough consideration of risk factors, comorbidities, and comedications that could interfere with HBO-related protection.

Considerations in detecting CDC select agents under field conditions

NASA Astrophysics Data System (ADS)

Spinelli, Charles; Soelberg, Scott; Swanson, Nathaneal; Furlong, Clement; Baker, Paul

2008-04-01

Surface Plasmon Resonance (SPR) has become a widely accepted technique for real-time detection of interactions between receptor molecules and ligands. Antibody may serve as receptor and can be attached to the gold surface of the SPR device, while candidate analyte fluids contact the detecting antibody. Minute, but detectable, changes in refractive indices (RI) indicate that analyte has bound to the antibody. A decade ago, an inexpensive, robust, miniature and fully integrated SPR chip, called SPREETA, was developed. University of Washington (UW) researchers subsequently developed a portable, temperature-regulated instrument, called SPIRIT, to simultaneously use eight of these three-channel SPREETA chips. A SPIRIT prototype instrument was tested in the field, coupled to a remote reporting system on a surrogate unmanned aerial vehicle (UAV). Two target protein analytes were released sequentially as aerosols with low analyte concentration during each of three flights and were successfully detected and verified. Laboratory experimentation with a more advanced SPIRIT instrument demonstrated detection of very low levels of several select biological agents that might be employed by bioterrorists. Agent detection under field-like conditions is more challenging, especially as analyte concentrations are reduced and complex matricies are introduced. Two different sample preconditioning protocols have been developed for select agents in complex matrices. Use of these preconditioning techniques has allowed laboratory detection in spiked heavy mud of Francisella tularensis at 10 3 CFU/ml, Bacillus anthracis spores at 10 3 CFU/ml, Staphylococcal enterotoxin B (SEB) at 1 ng/ml, and Vaccinia virus (a smallpox simulant) at 10 5 PFU/ml. Ongoing experiments are aimed at simultaneous detection of multiple agents in spiked heavy mud, using a multiplex preconditioning protocol.

Role of Heat Shock Protein 90 and Endothelial Nitric Oxide Synthase during Early Anesthetic and Ischemic Preconditioning

PubMed Central

Amour, Julien; Brzezinska, Anna K.; Weihrauch, Dorothee; Billstrom, Amie R.; Zielonka, Jacek; Krolikowski, John G.; Bienengraeber, Martin W.; Warltier, David C.; Pratt, Philip F.; Kersten, Judy R.

2009-01-01

Background Nitric oxide is known to be essential for early anesthetic (APC) and ischemic (IPC) preconditioning of myocardium. Heat shock protein 90 (Hsp90) regulates endothelial nitric oxide synthase (eNOS) activity. In this study, we tested the hypothesis that Hsp90-eNOS interactions modulate APC and IPC. Methods Myocardial infarct size was measured in rabbits after coronary occlusion and reperfusion in the absence or presence of preconditioning with 30 min of isoflurane (APC) or 5 min of coronary artery occlusion (IPC), and with or without pre-treatment with geldanamycin or radicicol, two chemically distinct Hsp90 inhibitors, or NG-nitro-L-arginine methylester, a non-specific NOS inhibitor. Isoflurane-dependent nitric oxide production was measured (ozone chemiluminescence) in human coronary artery endothelial cells or mouse cardiomyocytes, in the absence or presence of Hsp90 inhibitors or NG-nitro-L-arginine methylester. Interactions between Hsp90 and eNOS, and eNOS activation were assessed with immunoprecipitation, immunoblotting, and confocal microscopy. Results APC and IPC decreased infarct size (50% and 59%, respectively) and this action was abolished by Hsp90 inhibitors. NG-nitro-L-arginine methylester blocked APC but not IPC. Isoflurane increased nitric oxide production in human coronary artery endothelial cells, concomitantly with an increase in Hsp90-eNOS interaction (immunoprecipitation, immunoblotting, and immunohistochemistry). Pretreatment with Hsp90 inhibitors abolished isoflurane-dependent nitric oxide production and decreased Hsp90-eNOS interactions. Isoflurane did not increase nitric oxide production in mouse cardiomyocytes and eNOS was below the level of detection. Conclusion The results indicate that Hsp90 plays a critical role in mediating APC and IPC through protein-protein interactions, and suggest that endothelial cells are important contributors to nitric oxide-mediated signalling during APC. PMID:19194158

The mechanism of protection from 5 (N-ethyl-N-isopropyl)amiloride differs from that of ischemic preconditioning in rabbit heart.

PubMed

Sato, H; Miki, T; Vallabhapurapu, R P; Wang, P; Liu, G S; Cohen, M V; Downey, J M

1997-10-01

We investigated the effects of 5-(N-ethyl-N-isopropyl)amiloride (EIPA) on infarction in isolated rabbit hearts and cardiomyocytes. Thirty min of regional ischemia caused 29.6 +/- 2.8% of the risk zone to infarct in untreated Krebs buffer-perfused hearts. Treatment with EIPA (1 microM) for 20 min starting either 15 min before ischemia or 15 min after the onset of ischemia significantly reduced infarction to 5.4 +/- 2.0% and 7.0 +/- 1.0%, respectively (p < 0.01 versus untreated hearts). In both cases salvage was very similar to that seen with ischemic preconditioning (PC) (7.1 +/- 1.5% infarction). Unlike the case with ischemic preconditioning, however, protection from EIPA was not blocked by 50 microM polymyxin B, a PKC inhibitor, or 1 microM glibenclamide, a KATP channel blocker. Forty-five min of regional ischemia caused 51.0 +/- 2.9% infarction in untreated hearts. Ischemic preconditioning reduced infarction to 23.4 +/- 3.1% (p < 0.001 versus untreated hearts). In these hearts with longer periods of ischemia pretreatment with EIPA reduced infarction similarly to 28.8 +/- 2.1% (p < 0.01 versus untreated hearts). However, when EIPA was combined with ischemic PC, no further reduction in infarction was seen (23.8 +/- 3.5% infarction). To further elucidate the mechanism of EIPA's cardioprotective effect, this agent was also examined in isolated rabbit cardiomyocytes. Preconditioning caused a delay of about 30 min in the progressive increase in osmotic fragility that occurs during simulated ischemia. In contrast, EIPA had no effect on the time course of ischemia-induced osmotic fragility. Furthermore, EIPA treatment did not alter the salutary effect of ischemic preconditioning when the two were combined in this model. We conclude that Na+/H+ exchange inhibition limits myocardial infarction in the isolated rabbit heart by a mechanism which is quite different from that of ischemic preconditioning. Despite the apparently divergent mechanisms, EIPA's cardioprotective effect could not be added to that of ischemic or metabolic preconditioning in these models.

Clonidine preconditioning improved cerebral ischemia-induced learning and memory deficits in rats via ERK1/2-CREB/ NF-κB-NR2B pathway.

PubMed

Li, Yanli; Yu, Min; Zhao, Bo; Wang, Yan; Zha, Yunhong; Li, Zicheng; Yu, Lingling; Yan, Lingling; Chen, Zhangao; Zhang, Wenjuan; Zeng, Xiaoli; He, Zhi

2018-01-05

Clonidine, a classical α-2 adrenergic agonists, has been shown to antagonize brain damage caused by hypoxia, cerebral ischemia and excitotoxicity and reduce cerebral infarction volume in recent studies. We herein investigate the regulatory effect and possible underlying mechanism of clonidine on learning and memory in rats with cerebral ischemia. The cerebral ischemia rat model was established by right middle cerebral artery occlusion for 2h and reperfusion for 28 days. Drugs were administrated to the rats for consecutive 7 days intraperitoneally and once again on the day of surgery. The learning and memory in rats was assayed by Morris water maze. Moreover, protein expression levels of NMDAR2B (NR2B)/ phosphor - NR2B, ERK1/2/phosphor- ERK1/2, CREB/phosphor-CREB and NF-κB/phosphor-NF-κB in the cortex and hippocampus of the rats were assayed by western blotting. Our results demonstrated that clonidine treatment significantly abrogated the negative effect induced by cerebral ischemia on the learning and memory in the rats. In the Western blotting assay, clonidine treatment led to significant up-regulation of the expression level of NR2B and Phospho-NR2B in the hippocampus of the rats when compared with the cerebral ischemia group. Furthermore, clonidine also significantly decreased the protein expression levels of ERK1/2, Phospho-ERK1/2, CREB, Phospho-CREB and Phospho-NF-κB in the hippocampus of the rats when compared with the cerebral ischemia group. In conclusion, clonidine could improve the learning and memory ability of rats with cerebral ischemia, and NR2B, ERK1/2, CREB, NF-κB were involved in this effect. Copyright © 2017 Elsevier B.V. All rights reserved.

Adjustment of Dysregulated Ceramide Metabolism in a Murine Model of Sepsis-Induced Cardiac Dysfunction

PubMed Central

Chung, Ha-Yeun; Kollmey, Anna S.; Schrepper, Andrea; Kohl, Matthias; Bläss, Markus F.; Stehr, Sebastian N.; Lupp, Amelie; Gräler, Markus H.; Claus, Ralf A.

2017-01-01

Cardiac dysfunction, in particular of the left ventricle, is a common and early event in sepsis, and is strongly associated with an increase in patients’ mortality. Acid sphingomyelinase (SMPD1)—the principal regulator for rapid and transient generation of the lipid mediator ceramide—is involved in both the regulation of host response in sepsis as well as in the pathogenesis of chronic heart failure. This study determined the degree and the potential role to which SMPD1 and its modulation affect sepsis-induced cardiomyopathy using both genetically deficient and pharmacologically-treated animals in a polymicrobial sepsis model. As surrogate parameters of sepsis-induced cardiomyopathy, cardiac function, markers of oxidative stress as well as troponin I levels were found to be improved in desipramine-treated animals, desipramine being an inhibitor of ceramide formation. Additionally, ceramide formation in cardiac tissue was dysregulated in SMPD1+/+ as well as SMPD1−/− animals, whereas desipramine pretreatment resulted in stable, but increased ceramide content during host response. This was a result of elevated de novo synthesis. Strikingly, desipramine treatment led to significantly improved levels of surrogate markers. Furthermore, similar results in desipramine-pretreated SMPD1−/− littermates suggest an SMPD1-independent pathway. Finally, a pattern of differentially expressed transcripts important for regulation of apoptosis as well as antioxidative and cytokine response supports the concept that desipramine modulates ceramide formation, resulting in beneficial myocardial effects. We describe a novel, protective role of desipramine during sepsis-induced cardiac dysfunction that controls ceramide content. In addition, it may be possible to modulate cardiac function during host response by pre-conditioning with the Food and Drug Administration (FDA)-approved drug desipramine. PMID:28420138

Adjustment of Dysregulated Ceramide Metabolism in a Murine Model of Sepsis-Induced Cardiac Dysfunction.

PubMed

Chung, Ha-Yeun; Kollmey, Anna S; Schrepper, Andrea; Kohl, Matthias; Bläss, Markus F; Stehr, Sebastian N; Lupp, Amelie; Gräler, Markus H; Claus, Ralf A

2017-04-15

Cardiac dysfunction, in particular of the left ventricle, is a common and early event in sepsis, and is strongly associated with an increase in patients' mortality. Acid sphingomyelinase (SMPD1)-the principal regulator for rapid and transient generation of the lipid mediator ceramide-is involved in both the regulation of host response in sepsis as well as in the pathogenesis of chronic heart failure. This study determined the degree and the potential role to which SMPD1 and its modulation affect sepsis-induced cardiomyopathy using both genetically deficient and pharmacologically-treated animals in a polymicrobial sepsis model. As surrogate parameters of sepsis-induced cardiomyopathy, cardiac function, markers of oxidative stress as well as troponin I levels were found to be improved in desipramine-treated animals, desipramine being an inhibitor of ceramide formation. Additionally, ceramide formation in cardiac tissue was dysregulated in SMPD1 +/+ as well as SMPD1 -/- animals, whereas desipramine pretreatment resulted in stable, but increased ceramide content during host response. This was a result of elevated de novo synthesis. Strikingly, desipramine treatment led to significantly improved levels of surrogate markers. Furthermore, similar results in desipramine-pretreated SMPD1 -/- littermates suggest an SMPD1-independent pathway. Finally, a pattern of differentially expressed transcripts important for regulation of apoptosis as well as antioxidative and cytokine response supports the concept that desipramine modulates ceramide formation, resulting in beneficial myocardial effects. We describe a novel, protective role of desipramine during sepsis-induced cardiac dysfunction that controls ceramide content. In addition, it may be possible to modulate cardiac function during host response by pre-conditioning with the Food and Drug Administration (FDA)-approved drug desipramine.

Nested Conjugate Gradient Algorithm with Nested Preconditioning for Non-linear Image Restoration.

PubMed

Skariah, Deepak G; Arigovindan, Muthuvel

2017-06-19

We develop a novel optimization algorithm, which we call Nested Non-Linear Conjugate Gradient algorithm (NNCG), for image restoration based on quadratic data fitting and smooth non-quadratic regularization. The algorithm is constructed as a nesting of two conjugate gradient (CG) iterations. The outer iteration is constructed as a preconditioned non-linear CG algorithm; the preconditioning is performed by the inner CG iteration that is linear. The inner CG iteration, which performs preconditioning for outer CG iteration, itself is accelerated by an another FFT based non-iterative preconditioner. We prove that the method converges to a stationary point for both convex and non-convex regularization functionals. We demonstrate experimentally that proposed method outperforms the well-known majorization-minimization method used for convex regularization, and a non-convex inertial-proximal method for non-convex regularization functional.

On adaptive weighted polynomial preconditioning for Hermitian positive definite matrices

NASA Technical Reports Server (NTRS)

Fischer, Bernd; Freund, Roland W.

1992-01-01

The conjugate gradient algorithm for solving Hermitian positive definite linear systems is usually combined with preconditioning in order to speed up convergence. In recent years, there has been a revival of polynomial preconditioning, motivated by the attractive features of the method on modern architectures. Standard techniques for choosing the preconditioning polynomial are based only on bounds for the extreme eigenvalues. Here a different approach is proposed, which aims at adapting the preconditioner to the eigenvalue distribution of the coefficient matrix. The technique is based on the observation that good estimates for the eigenvalue distribution can be derived after only a few steps of the Lanczos process. This information is then used to construct a weight function for a suitable Chebyshev approximation problem. The solution of this problem yields the polynomial preconditioner. In particular, we investigate the use of Bernstein-Szego weights.

Antidepressant-like effects of mild hypoxia preconditioning in the learned helplessness model in rats.

PubMed

Rybnikova, Elena; Mironova, Vera; Pivina, Svetlana; Tulkova, Ekaterina; Ordyan, Natalia; Vataeva, Ludmila; Vershinina, Elena; Abritalin, Eugeny; Kolchev, Alexandr; Nalivaeva, Natalia; Turner, Anthony J; Samoilov, Michail

2007-05-07

The effects of preconditioning using mild repetitive hypobaric hypoxia (360 Torr for 2 h each of 3 days) have been studied in the learned helplessness model of depression in rats. Male Wistar rats displayed persistent depressive symptoms (depressive-like behaviour in open field, increased anxiety levels in elevated plus maze, ahedonia, elevated plasma glucocorticoids and impaired dexamethasone test) following the exposure to unpredictable and inescapable footshock in the learned helplessness paradigm. Antidepressant treatment (ludiomil, 5 mg/kg i.p.) augmented the development of the depressive state. The hypoxic preconditioning had a clear antidepressive action returning the behavioural and hormonal parameters to the control values and was equally effective in terms of our study as the antidepressant. The findings suggest hypoxic preconditioning as an effective tool for the prophylaxis of post-stress affective pathologies in humans.

Preconditioned characteristic boundary conditions based on artificial compressibility method for solution of incompressible flows

NASA Astrophysics Data System (ADS)

Hejranfar, Kazem; Parseh, Kaveh

2017-09-01

The preconditioned characteristic boundary conditions based on the artificial compressibility (AC) method are implemented at artificial boundaries for the solution of two- and three-dimensional incompressible viscous flows in the generalized curvilinear coordinates. The compatibility equations and the corresponding characteristic variables (or the Riemann invariants) are mathematically derived and then applied as suitable boundary conditions in a high-order accurate incompressible flow solver. The spatial discretization of the resulting system of equations is carried out by the fourth-order compact finite-difference (FD) scheme. In the preconditioning applied here, the value of AC parameter in the flow field and also at the far-field boundary is automatically calculated based on the local flow conditions to enhance the robustness and performance of the solution algorithm. The code is fully parallelized using the Concurrency Runtime standard and Parallel Patterns Library (PPL) and its performance on a multi-core CPU is analyzed. The incompressible viscous flows around a 2-D circular cylinder, a 2-D NACA0012 airfoil and also a 3-D wavy cylinder are simulated and the accuracy and performance of the preconditioned characteristic boundary conditions applied at the far-field boundaries are evaluated in comparison to the simplified boundary conditions and the non-preconditioned characteristic boundary conditions. It is indicated that the preconditioned characteristic boundary conditions considerably improve the convergence rate of the solution of incompressible flows compared to the other boundary conditions and the computational costs are significantly decreased.

Condition number estimation of preconditioned matrices.

PubMed

Kushida, Noriyuki

2015-01-01

The present paper introduces a condition number estimation method for preconditioned matrices. The newly developed method provides reasonable results, while the conventional method which is based on the Lanczos connection gives meaningless results. The Lanczos connection based method provides the condition numbers of coefficient matrices of systems of linear equations with information obtained through the preconditioned conjugate gradient method. Estimating the condition number of preconditioned matrices is sometimes important when describing the effectiveness of new preconditionerers or selecting adequate preconditioners. Operating a preconditioner on a coefficient matrix is the simplest method of estimation. However, this is not possible for large-scale computing, especially if computation is performed on distributed memory parallel computers. This is because, the preconditioned matrices become dense, even if the original matrices are sparse. Although the Lanczos connection method can be used to calculate the condition number of preconditioned matrices, it is not considered to be applicable to large-scale problems because of its weakness with respect to numerical errors. Therefore, we have developed a robust and parallelizable method based on Hager's method. The feasibility studies are curried out for the diagonal scaling preconditioner and the SSOR preconditioner with a diagonal matrix, a tri-daigonal matrix and Pei's matrix. As a result, the Lanczos connection method contains around 10% error in the results even with a simple problem. On the other hand, the new method contains negligible errors. In addition, the newly developed method returns reasonable solutions when the Lanczos connection method fails with Pei's matrix, and matrices generated with the finite element method.

Acidic preconditioning of endothelial colony-forming cells (ECFC) promote vasculogenesis under proinflammatory and high glucose conditions in vitro and in vivo.

PubMed

Mena, Hebe Agustina; Zubiry, Paula Romina; Dizier, Blandine; Schattner, Mirta; Boisson-Vidal, Catherine; Negrotto, Soledad

2018-05-02

We have previously demonstrated that acidic preconditioning of human endothelial colony-forming cells (ECFC) increased proliferation, migration, and tubulogenesis in vitro, and increased their regenerative potential in a murine model of hind limb ischemia without baseline disease. We now analyze whether this strategy is also effective under adverse conditions for vasculogenesis, such as the presence of ischemia-related toxic molecules or diabetes, one of the main target diseases for cell therapy due to their well-known healing impairments. Cord blood-derived CD34 + cells were seeded in endothelial growth culture medium (EGM2) and ECFC colonies were obtained after 14-21 days. ECFC were exposed at pH 6.6 (preconditioned) or pH 7.4 (nonpreconditioned) for 6 h, and then pH was restored at 7.4. A model of type 2 diabetes induced by a high-fat and high-sucrose diet was developed in nude mice and hind limb ischemia was induced in these animals by femoral artery ligation. A P value < 0.05 was considered statistically significant (by one-way analysis of variance). We found that acidic preconditioning increased ECFC adhesion and the release of pro-angiogenic molecules, and protected ECFC from the cytotoxic effects of monosodium urate crystals, histones, and tumor necrosis factor (TNF)α, which induced necrosis, pyroptosis, and apoptosis, respectively. Noncytotoxic concentrations of high glucose, TNFα, or their combination reduced ECFC proliferation, stromal cell-derived factor (SDF)1-driven migration, and tubule formation on a basement membrane matrix, whereas almost no inhibition was observed in preconditioned ECFC. In type 2 diabetic mice, intravenous administration of preconditioned ECFC significantly induced blood flow recovery at the ischemic limb as measured by Doppler, compared with the phosphate-buffered saline (PBS) and nonpreconditioned ECFC groups. Moreover, the histologic analysis of gastrocnemius muscles showed an increased vascular density and reduced signs of inflammation in the animals receiving preconditioned ECFC. Acidic preconditioning improved ECFC survival and angiogenic activity in the presence of proinflammatory and damage signals present in the ischemic milieu, even under high glucose conditions, and increased their therapeutic potential for postischemia tissue regeneration in a murine model of type 2 diabetes. Collectively, our data suggest that acidic preconditioning of ECFC is a simple and inexpensive strategy to improve the effectiveness of cell transplantation in diabetes, where tissue repair is highly compromised.

TRPV1 Agonist, Capsaicin, Induces Axon Outgrowth after Injury via Ca2+/PKA Signaling.

PubMed

Frey, Erin; Karney-Grobe, Scott; Krolak, Trevor; Milbrandt, Jeff; DiAntonio, Aaron

2018-01-01

Preconditioning nerve injuries activate a pro-regenerative program that enhances axon regeneration for most classes of sensory neurons. However, nociceptive sensory neurons and central nervous system neurons regenerate poorly. In hopes of identifying novel mechanisms that promote regeneration, we screened for drugs that mimicked the preconditioning response and identified a nociceptive ligand that activates a preconditioning-like response to promote axon outgrowth. We show that activating the ion channel TRPV1 with capsaicin induces axon outgrowth of cultured dorsal root ganglion (DRG) sensory neurons, and that this effect is blocked in TRPV1 knockout neurons. Regeneration occurs only in NF200-negative nociceptive neurons, consistent with a cell-autonomous mechanism. Moreover, we identify a signaling pathway in which TRPV1 activation leads to calcium influx and protein kinase A (PKA) activation to induce a preconditioning-like response. Finally, capsaicin administration to the mouse sciatic nerve activates a similar preconditioning-like response and induces enhanced axonal outgrowth, indicating that this pathway can be induced in vivo . These findings highlight the use of local ligands to induce regeneration and suggest that it may be possible to target selective neuronal populations for repair, including cell types that often fail to regenerate.

Ischemic Preconditioning Increases the Tolerance of Fatty Liver to Hepatic Ischemia-Reperfusion Injury in the Rat

PubMed Central

Serafín, Anna; Roselló-Catafau, Joan; Prats, Neus; Xaus, Carme; Gelpí, Emilio; Peralta, Carmen

2002-01-01

Hepatic steatosis is a major risk factor in ischemia-reperfusion. The present study evaluates whether preconditioning, demonstrated to be effective in normal livers, could also confer protection in the presence of steatosis and investigates the potential underlying protective mechanisms. Fatty rats had increased hepatic injury and decreased survival after 60 minutes of ischemia compared with lean rats. Fatty livers showed a degree of neutrophil accumulation and microcirculatory alterations similar to that of normal livers. However, in presence of steatosis, an increased lipid peroxidation that could be reduced with glutathione-ester pretreatment was observed after hepatic reperfusion. Ischemic preconditioning reduced hepatic injury and increased animal survival. Both in normal and fatty livers, this endogenous protective mechanism was found to control lipid peroxidation, hepatic microcirculation failure, and neutrophil accumulation, reducing the subsequent hepatic injury. These beneficial effects could be mediated by nitric oxide, because the inhibition of nitric oxide synthesis and nitric oxide donor pretreatment abolished and simulated, respectively, the benefits of preconditioning. Thus, ischemic preconditioning could be an effective surgical strategy to reduce the hepatic ischemia-reperfusion injury in normal and fatty livers under normothermic conditions, including hepatic resections, and liver transplantation. PMID:12163383

Impact of remote ischemic preconditioning on wound healing in small bowel anastomoses

PubMed Central

Holzner, Philipp Anton; Kulemann, Birte; Kuesters, Simon; Timme, Sylvia; Hoeppner, Jens; Hopt, Ulrich Theodor; Marjanovic, Goran

2011-01-01

AIM: To investigate the influence of remote ischemic preconditioning (RIPC) on anastomotic integrity. METHODS: Sixty male Wistar rats were randomized to six groups. The control group (n = 10) had an end-to-end ileal anastomosis without RIPC. The preconditioned groups (n = 34) varied in time of ischemia and time of reperfusion. One group received the amino acid L-arginine before constructing the anastomosis (n = 9). On postoperative day 4, the rats were re-laparotomized, and bursting pressure, hydroxyproline concentration, intra-abdominal adhesions, and a histological score concerning the mucosal ischemic injury were collected. The data are given as median (range). RESULTS: On postoperative day 4, median bursting pressure was 124 mmHg (60-146 mmHg) in the control group. The experimental groups did not show a statistically significant difference (P > 0.05). Regarding the hydroxyproline concentration, we did not find any significant variation in the experimental groups. We detected significantly less mucosal injury in the RIPC groups. Furthermore, we assessed more extensive intra-abdominal adhesions in the preconditioned groups than in the control group. CONCLUSION: RIPC directly before performing small bowel anastomosis does not affect anastomotic stability in the early period, as seen in ischemic preconditioning. PMID:21455330

Using Chebyshev polynomials and approximate inverse triangular factorizations for preconditioning the conjugate gradient method

NASA Astrophysics Data System (ADS)

Kaporin, I. E.

2012-02-01

In order to precondition a sparse symmetric positive definite matrix, its approximate inverse is examined, which is represented as the product of two sparse mutually adjoint triangular matrices. In this way, the solution of the corresponding system of linear algebraic equations (SLAE) by applying the preconditioned conjugate gradient method (CGM) is reduced to performing only elementary vector operations and calculating sparse matrix-vector products. A method for constructing the above preconditioner is described and analyzed. The triangular factor has a fixed sparsity pattern and is optimal in the sense that the preconditioned matrix has a minimum K-condition number. The use of polynomial preconditioning based on Chebyshev polynomials makes it possible to considerably reduce the amount of scalar product operations (at the cost of an insignificant increase in the total number of arithmetic operations). The possibility of an efficient massively parallel implementation of the resulting method for solving SLAEs is discussed. For a sequential version of this method, the results obtained by solving 56 test problems from the Florida sparse matrix collection (which are large-scale and ill-conditioned) are presented. These results show that the method is highly reliable and has low computational costs.

Beneficial effects of remote organ ischemic preconditioning on micro-rheological parameters during liver ischemia-reperfusion in the rat.

PubMed

Magyar, Zsuzsanna; Mester, Anita; Nadubinszky, Gabor; Varga, Gabor; Ghanem, Souleiman; Somogyi, Viktoria; Tanczos, Bence; Deak, Adam; Bidiga, Laszlo; Oltean, Mihai; Peto, Katalin; Nemeth, Norbert

2018-04-14

Remote ischemic preconditioning (RIPC) can be protective against the damage. However, there is no consensus on the optimal amount of tissue, the number and duration of the ischemic cycles, and the timing of the preconditioning. The hemorheological background of the process is also unknown. To investigate the effects of remote organ ischemic preconditioning on micro-rheological parameters during liver ischemia-reperfusion in rats. In anesthetized rats 60-minute partial liver ischemia was induced with 120-minute reperfusion (Control, n = 7). In the preconditioned groups a tourniquet was applied on the left thigh for 3×10 minutes 1 hour (RIPC-1, n = 7) or 24 hours (RIPC-24, n = 7) prior to the liver ischemia. Blood samples were taken before the operation and during the reperfusion. Acid-base, hematological parameters, erythrocyte aggregation and deformability were tested. Lactate concentration significantly increased by the end of the reperfusion. Erythrocyte deformability was improved in the RIPC-1 group, erythrocyte aggregation increased during the reperfusion, particularly in the RIPC-24 group. RIPC alleviated several hemorheological changes caused by the liver I/R. However, the optimal timing of the RIPC cannot be defined based on these results.

Molecular strategies of the Caenorhabditis elegans dauer larva to survive extreme desiccation.

PubMed

Erkut, Cihan; Vasilj, Andrej; Boland, Sebastian; Habermann, Bianca; Shevchenko, Andrej; Kurzchalia, Teymuras V

2013-01-01

Massive water loss is a serious challenge for terrestrial animals, which usually has fatal consequences. However, some organisms have developed means to survive this stress by entering an ametabolic state called anhydrobiosis. The molecular and cellular mechanisms underlying this phenomenon are poorly understood. We recently showed that Caenorhabditis elegans dauer larva, an arrested stage specialized for survival in adverse conditions, is resistant to severe desiccation. However, this requires a preconditioning step at a mild desiccative environment to prepare the organism for harsher desiccation conditions. A systems approach was used to identify factors that are activated during this preconditioning. Using microarray analysis, proteomics, and bioinformatics, genes, proteins, and biochemical pathways that are upregulated during this process were identified. These pathways were validated via reverse genetics by testing the desiccation tolerances of mutants. These data show that the desiccation response is activated by hygrosensation (sensing the desiccative environment) via head neurons. This leads to elimination of reactive oxygen species and xenobiotics, expression of heat shock and intrinsically disordered proteins, polyamine utilization, and induction of fatty acid desaturation pathway. Remarkably, this response is specific and involves a small number of functional pathways, which represent the generic toolkit for anhydrobiosis in plants and animals.

Ratios and effect size.

PubMed

Robinson, Jasper

2017-10-01

Responding to a related pair of measurements is often expressed as a single discrimination ratio. Authors have used various discrimination ratios; yet, little information exists to guide their choice. A second use of ratios is to correct for the influence of a nuisance variable on the measurement of interest. I examine 4 discrimination ratios using simulated data sets. Three ratios, of the form a/(a + b), b/(a + b), and (a - b)/(a + b), introduced distortions to their raw data. The fourth ratio, (b - a)/b largely avoided such distortions and was the most sensitive at detecting statistical differences. Effect size statistics were also often improved with a correction ratio. Gustatory sensory preconditioning experiments involved measurement of rats' sucrose and saline consumption; these flavors served as either a target flavor or a control flavor and were counterbalanced across rats. However, sensory preconditioning was often masked by a bias for sucrose over saline. Sucrose and saline consumption scores were multiplied by the ratio of the overall consumption to the consumption of that flavor alone, which corrected the bias. The general utility of discrimination and correction ratios for data treatment is discussed. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Mechanical stretch endows mesenchymal stem cells stronger angiogenic and anti-apoptotic capacities via NFκB activation

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

Zhu, Zhuoli; Gan, Xueqi; Fan, Hongyi

Mesenchymal stem cells (MSCs) have been broadly used for tissue regeneration and repair due to their broad differentiation potential and potent paracrine properties such as angiogenic capacity. Strategies to increase their survival rate after transplantation and the angiogenic ability are of priority for the utility of MSCs. In this study, we found that mechanical stretch (10% extension, 30 cycles/min cyclic stretch) preconditioning increase the angiogenic capacity via VEGFA induction. In addition, mechanical stretch also increases the survival rate of mesenchymal stem cells under nutrients deprivation. Consistent with the increase VEGFA expression and resistance to apoptosis, nuclear localization of NFκB activity p65more » increased upon mechanical stretch. Inhibition of NFκB activity by BAY 11-708 blocks the pro-angiogenesis and anti-apoptosis function of mechanical stretch. Taken together, our findings here raise the possibility that mechanical stretch preconditioning might enhance the therapeutic efficacy of mesenchymal stem cells. - Highlights: • Mechanical stretch increases the angiogenic capacity via VEGFA induction in MSCs. • Mechanical stretch increases the survival rate of MSCs under nutrients deprivation. • Mechanical stretch manipulates MSCs via the activation of NFκB.« less

Brain ischemic preconditioning protects against ischemic injury and preserves the blood-brain barrier via oxidative signaling and Nrf2 activation.

PubMed

Yang, Tuo; Sun, Yang; Mao, Leilei; Zhang, Meijuan; Li, Qianqian; Zhang, Lili; Shi, Yejie; Leak, Rehana K; Chen, Jun; Zhang, Feng

2018-05-06

Brain ischemic preconditioning (IPC) with mild ischemic episodes is well known to protect the brain against subsequent ischemic challenges. However, the underlying mechanisms are poorly understood. Here we demonstrate the critical role of the master redox transcription factor, nuclear factor (erythroid-derived 2)-like 2 (Nrf2), in IPC-mediated neuroprotection and blood-brain barrier (BBB) preservation. We report that IPC causes generation of endogenous lipid electrophiles, including 4-hydroxy-2-nonenal (4-HNE), which release Nrf2 from inhibition by Keap1 (via Keap1-C288) and inhibition by glycogen synthase kinase 3β (via GSK3β-C199). Nrf2 then induces expression of its target genes, including a new target, cadherin 5, a key component of adherens junctions of the BBB. These effects culminate in mitigation of BBB leakage and of neurological deficits after stroke. Collectively, these studies are the first to demonstrate that IPC protects the BBB against ischemic injury by generation of endogenous electrophiles and activation of the Nrf2 pathway through inhibition of Keap1- and GSK3β-dependent Nrf2 degradation. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Molecular Strategies of the Caenorhabditis elegans Dauer Larva to Survive Extreme Desiccation

PubMed Central

Erkut, Cihan; Vasilj, Andrej; Boland, Sebastian; Habermann, Bianca; Shevchenko, Andrej; Kurzchalia, Teymuras V.

2013-01-01

Massive water loss is a serious challenge for terrestrial animals, which usually has fatal consequences. However, some organisms have developed means to survive this stress by entering an ametabolic state called anhydrobiosis. The molecular and cellular mechanisms underlying this phenomenon are poorly understood. We recently showed that Caenorhabditis elegans dauer larva, an arrested stage specialized for survival in adverse conditions, is resistant to severe desiccation. However, this requires a preconditioning step at a mild desiccative environment to prepare the organism for harsher desiccation conditions. A systems approach was used to identify factors that are activated during this preconditioning. Using microarray analysis, proteomics, and bioinformatics, genes, proteins, and biochemical pathways that are upregulated during this process were identified. These pathways were validated via reverse genetics by testing the desiccation tolerances of mutants. These data show that the desiccation response is activated by hygrosensation (sensing the desiccative environment) via head neurons. This leads to elimination of reactive oxygen species and xenobiotics, expression of heat shock and intrinsically disordered proteins, polyamine utilization, and induction of fatty acid desaturation pathway. Remarkably, this response is specific and involves a small number of functional pathways, which represent the generic toolkit for anhydrobiosis in plants and animals. PMID:24324795

Preconditioned upwind methods to solve 3-D incompressible Navier-Stokes equations for viscous flows

NASA Technical Reports Server (NTRS)

Hsu, C.-H.; Chen, Y.-M.; Liu, C. H.

1990-01-01

A computational method for calculating low-speed viscous flowfields is developed. The method uses the implicit upwind-relaxation finite-difference algorithm with a nonsingular eigensystem to solve the preconditioned, three-dimensional, incompressible Navier-Stokes equations in curvilinear coordinates. The technique of local time stepping is incorporated to accelerate the rate of convergence to a steady-state solution. An extensive study of optimizing the preconditioned system is carried out for two viscous flow problems. Computed results are compared with analytical solutions and experimental data.

Choice of Variables and Preconditioning for Time Dependent Problems

NASA Technical Reports Server (NTRS)

Turkel, Eli; Vatsa, Verr N.

2003-01-01

We consider the use of low speed preconditioning for time dependent problems. These are solved using a dual time step approach. We consider the effect of this dual time step on the parameter of the low speed preconditioning. In addition, we compare the use of two sets of variables, conservation and primitive variables, to solve the system. We show the effect of these choices on both the convergence to a steady state and the accuracy of the numerical solutions for low Mach number steady state and time dependent flows.

Preconditioning the Helmholtz Equation for Rigid Ducts

NASA Technical Reports Server (NTRS)

Baumeister, Kenneth J.; Kreider, Kevin L.

1998-01-01

An innovative hyperbolic preconditioning technique is developed for the numerical solution of the Helmholtz equation which governs acoustic propagation in ducts. Two pseudo-time parameters are used to produce an explicit iterative finite difference scheme. This scheme eliminates the large matrix storage requirements normally associated with numerical solutions to the Helmholtz equation. The solution procedure is very fast when compared to other transient and steady methods. Optimization and an error analysis of the preconditioning factors are present. For validation, the method is applied to sound propagation in a 2D semi-infinite hard wall duct.

The Role of Ionospheric Outflow Preconditioning in Determining Storm Geoeffectiveness

NASA Astrophysics Data System (ADS)

Welling, D. T.; Liemohn, M. W.; Ridley, A. J.

2012-12-01

It is now well accepted that ionospheric outflow plays an important role in the development of the plasma sheet and ring current during geomagnetic storms. Furthermore, even during quiet times, ionospheric plasma populates the magnetospheric lobes, producing a reservoir of hydrogen and oxygen ions. When the Interplanetary Magnetic Field (IMF) turns southward, this reservoir is connected to the plasma sheet and ring current through magnetospheric convection. Hence, the conditions of the ionosphere and magnetospheric lobes leading up to magnetospheric storm onset have important implications for storm development. Despite this, there has been little research on this preconditioning; most global simulations begin just before storm onset, neglecting preconditioning altogether. This work explores the role of preconditioning in determining the geoeffectiveness of storms using a coupled global model system. A model of ionospheric outflow (the Polar Wind Outflow Model, PWOM) is two-way coupled to a global magnetohydrodynamic model (the Block-Adaptive Tree Solar wind Roe-type Upwind Scheme, BATS-R-US), which in turn drives a ring current model (the Ring current Atmosphere interactions Model, RAM). This unique setup is used to simulate an idealized storm. The model is started at many different times, from 1 hour before storm onset to 12 hours before. The effects of storm preconditioning are examined by investigating the total ionospheric plasma content in the lobes just before onset, the total ionospheric contribution in the ring current just after onset, and the effects on Dst, magnetic elevation angle at geosynchronous, and total ring current energy density. This experiment is repeated for different solar activity levels as set by F10.7 flux. Finally, a synthetic double-dip storm is constructed to see how two closely spaced storms affect each other by changing the preconditioning environment. It is found that preconditioning of the magnetospheric lobes via ionospheric outflow greatly influences the geoeffectiveness of magnetospheric storms.

Flap preconditioning by pressure-controlled cupping in a rat model.

PubMed

Koh, Kyung S; Park, Sung Woo; Oh, Tae Suk; Choi, Jong Woo

2016-08-01

Flap survival is essential for the success of soft-tissue reconstruction. Accordingly, various surgical and medical methods aim to increase flap survival. Because flap survival is affected by the innate vascular supply, traditional preconditioning methods mainly target vasodilatation or vascular reorientation to increase blood flow to the tissue. External stress on the skin, such as an external volume expander or cupping, induces vascular remodeling, and these approaches have been used in the fat grafting field and in traditional Asian medicine. In the present study, we used a rat random-pattern dorsal flap model to study the effectiveness of preconditioning with an externally applied device (cupping) at the flap site that directly applied negative pressure to the skin. The device, the pressure-controlled cupping, is connected to negative pressure vacuum device providing accurate pressure control from 0 mm Hg to -200 mm Hg. Flap surgery was performed after preconditioning under -25 mm Hg suction pressure for 30 min a day for 5 d, followed by 9 d of postoperative observation. Flap survival was assessed as the area of viable tissue and was compared between the preconditioned group and a control group. The preconditioned group showed absolute percentage increase of flap viability relative to the entire flap by 19.0± 7.6% (average 70.1% versus 51.0%). Tissue perfusion of entire flap, evaluated by laser Doppler imaging system, was improved with absolute percentage increase by 24.2± 10.4% (average 77.4% versus 53.1%). Histologic analysis of hematoxylin and eosin, CD31, and Masson-trichrome staining showed increased vascular density in the subdermal plexus and more organized collagen production with hypertrophy of the attached muscle. Our study suggests that flap preconditioning caused by controlled noninvasive suction induces vascular remodeling that increases tissue perfusion and improves flap survival in a rat model. Copyright © 2016 Elsevier Inc. All rights reserved.

Protective effect of naringin against the LPS-induced apoptosis of PC12 cells: Implications for the treatment of neurodegenerative disorders

PubMed Central

Wang, Hui; Xu, You Song; Wang, Miao Lin; Cheng, Chao; Bian, Rui; Yuan, Hao; Wang, Yi; Guo, Ting; Zhu, Lin Lin; Zhou, Hang

2017-01-01

Several studies have demonstrated that increased apoptosis plays an essential role in neurodegenerative disorders. It has been demonstrated that lipopolysaccharide (LPS) induces apoptosis largely through the production of intracellular reactive oxygen species (ROS) and inflammatory mediators. In this study, we investigated the potential protective mechanisms of naringin (Nar), a pummelo peel extract, on LPS-induced PC12 cell apoptosis. Nar pre-conditioning prior to stimulation with LPS for 18 h was a prerequisite for evaluating PC12 cell viability and the protective mechanisms of Nar. Nar significantly improved cell survival in a time- and concentration-dependent manner. On the one hand, Nar downregulated cytochrome P450 2E1 (CYP2E1), inhibited the release of ROS, mitigated the stimulation of oxidative stress, and rectified the antioxidant protein contents of nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), superoxide dismutase (SOD)2 and glutathione synthetase (GSS). On the other hand, Nar down-regulated inflammatory gene and protein expression, including interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, HMGB1, high mobility group box 1 protein (HMGB1), cyclo-oxygenase-2 (COX-2), the Toll-like receptor 4 (TLR4)-myeloid differentiation factor 88 (MyD88)-TNF receptor-associated factor 6 (TRAF6) path way and downstream mitogen activated protein kinase (MAPK) phosphorylation, activator protein transcription factor-1 (AP-1) and nuclear factor (NF)-κB. Moroever, Nar markedly attenuated the cytochrome c shift from the mitochondria to the cytosol and regulated caspase-3-related protein expression. To the best of our knowledge, this is the first study to report the antioxidant, anti-inflammatory and anti-apoptotic effects of Nar in neuronal-like PC12 cells. These results suggest that Nar can be utilized as a potential drug for the treatment of neurodegenerative disorders. PMID:28260042

Preconditioned conjugate gradient technique for the analysis of symmetric anisotropic structures

NASA Technical Reports Server (NTRS)

Noor, Ahmed K.; Peters, Jeanne M.

1987-01-01

An efficient preconditioned conjugate gradient (PCG) technique and a computational procedure are presented for the analysis of symmetric anisotropic structures. The technique is based on selecting the preconditioning matrix as the orthotropic part of the global stiffness matrix of the structure, with all the nonorthotropic terms set equal to zero. This particular choice of the preconditioning matrix results in reducing the size of the analysis model of the anisotropic structure to that of the corresponding orthotropic structure. The similarities between the proposed PCG technique and a reduction technique previously presented by the authors are identified and exploited to generate from the PCG technique direct measures for the sensitivity of the different response quantities to the nonorthotropic (anisotropic) material coefficients of the structure. The effectiveness of the PCG technique is demonstrated by means of a numerical example of an anisotropic cylindrical panel.

[The effect of hypoxia preconditioning no binding activity of HIF-1 on the HRE with EPO in the hippocampus of mice].

PubMed

Shao, Guo; Zhou, Wei-Hua; Gao, Cui-Ying; Zhang, Ran; Lu, Guo-Wei

2007-02-01

To observe change of binding activity of HIF-1 with erythropoietin (EPO) hypoxia response element (HRE) in the hippocampus of mice preconditioned to hypoxia and explore relationship between the changes and the preconditioning. The hippocampus was removed from mice exposed to hypoxia for 0 run (control group), 1 run (H1 group) and 4 runs(H4 group). Electrophoretic mobility shift assays (EMSA), chromatin immunoprecipitation (ChIP)and real time PCR were used to detect the change of activity of HIF-1 on HRE of EPO. Both in vitro and in vivo binding tests showed that the HIF-1 DNA-binding activities were increased in group H1 and markedly increased in group H4. The increase of HIF-1 and HRE of EPO binding activities is thought be involved in hypoxic preconditioning.

A Robust Locally Preconditioned Semi-Coarsening Multigrid Algorithm for the 2-D Navier-Stokes Equations

NASA Technical Reports Server (NTRS)

Cain, Michael D.

1999-01-01

The goal of this thesis is to develop an efficient and robust locally preconditioned semi-coarsening multigrid algorithm for the two-dimensional Navier-Stokes equations. This thesis examines the performance of the multigrid algorithm with local preconditioning for an upwind-discretization of the Navier-Stokes equations. A block Jacobi iterative scheme is used because of its high frequency error mode damping ability. At low Mach numbers, the performance of a flux preconditioner is investigated. The flux preconditioner utilizes a new limiting technique based on local information that was developed by Siu. Full-coarsening and-semi-coarsening are examined as well as the multigrid V-cycle and full multigrid. The numerical tests were performed on a NACA 0012 airfoil at a range of Mach numbers. The tests show that semi-coarsening with flux preconditioning is the most efficient and robust combination of coarsening strategy, and iterative scheme - especially at low Mach numbers.

Efficient Multi-Stage Time Marching for Viscous Flows via Local Preconditioning

NASA Technical Reports Server (NTRS)

Kleb, William L.; Wood, William A.; vanLeer, Bram

1999-01-01

A new method has been developed to accelerate the convergence of explicit time-marching, laminar, Navier-Stokes codes through the combination of local preconditioning and multi-stage time marching optimization. Local preconditioning is a technique to modify the time-dependent equations so that all information moves or decays at nearly the same rate, thus relieving the stiffness for a system of equations. Multi-stage time marching can be optimized by modifying its coefficients to account for the presence of viscous terms, allowing larger time steps. We show it is possible to optimize the time marching scheme for a wide range of cell Reynolds numbers for the scalar advection-diffusion equation, and local preconditioning allows this optimization to be applied to the Navier-Stokes equations. Convergence acceleration of the new method is demonstrated through numerical experiments with circular advection and laminar boundary-layer flow over a flat plate.

Peptide Nanofibers Preconditioned with Stem Cell Secretome Are Renoprotective

PubMed Central

Wang, Yin; Bakota, Erica; Chang, Benny H.J.; Entman, Mark; Hartgerink, Jeffrey D.

2011-01-01

Stem cells may contribute to renal recovery following acute kidney injury, and this may occur through their secretion of cytokines, chemokines, and growth factors. Here, we developed an acellular, nanofiber-based preparation of self-assembled peptides to deliver the secretome of embryonic stem cells (ESCs). Using an integrated in vitro and in vivo approach, we found that nanofibers preconditioned with ESCs could reverse cell hyperpermeability and apoptosis in vitro and protect against lipopolysaccharide-induced acute kidney injury in vivo. The renoprotective effect of preconditioned nanofibers associated with an attenuation of Rho kinase activation. We also observed that the combined presence of follistatin, adiponectin, and secretory leukoprotease during preconditioning was essential to the renoprotective properties of the nanofibers. In summary, we developed a designer-peptide nanofiber that can serve as a delivery platform for the beneficial effects of stem cells without the problems of teratoma formation or limited cell engraftment and viability. PMID:21415151

In vitro differentiated hepatic oval-like cells enhance hepatic regeneration in CCl4 -induced hepatic injury.

PubMed

Awan, Sana Javaid; Baig, Maria Tayyab; Yaqub, Faiza; Tayyeb, Asima; Ali, Gibran

2017-01-01

Hepatic oval cells are likely to be activated during advanced stage of liver fibrosis to reconstruct damaged hepatic tissue. However, their scarcity, difficulties in isolation, and in vitro expansion hampered their transplantation in fibrotic liver. This study was aimed to investigate the repair potential of in vitro differentiated hepatic oval-like cells in CCl 4 -induced liver fibrosis. BMSCs and oval cells were isolated and characterized from C57BL/6 GFP + mice. BMSCs were differentiated into oval cells by preconditioning with HGF, EGF, SCF, and LIF and analyzed for the oval cells-specific genes. Efficiency of oval cells to reduce hepatocyte injury was studied by determining cell viability, release of LDH, and biochemical tests in a co-culture system. Further, in vivo repair potential of differentiated oval cells was determined in CCl 4 -induced fibrotic model by gene expression analysis, biochemical tests, mason trichrome, and Sirius red staining. Differentiated oval cells expressed hepatic oval cells-specific markers AFP, ALB, CK8, CK18, CK19. These differentiated cells when co-cultured with injured hepatocytes showed significant hepato-protection as measured by reduction in apoptosis, LDH release, and improvement in liver functions. Transplantation of differentiated oval cells like cells in fibrotic livers exhibited enhanced homing, reduced liver fibrosis, and improved liver functions by augmenting hepatic microenvironment by improved liver functions. This preconditioning strategy to differentiate BMSCs into oval cell leads to improved survival and homing of transplanted cells. In addition, reduction in fibrosis and functional improvement in mice with CCl 4 -induced liver fibrosis was achieved. © 2016 International Federation for Cell Biology.

Understanding the biology of ex vivo-expanded CD8 T cells for adoptive cell therapy: role of CD62L.

PubMed

Díaz-Montero, C Marcela; Zidan, Abdel-Aziz; Pallin, Maria F; Anagnostopoulos, Vasileios; Salem, Mohamed L; Wieder, Eric; Komanduri, Krishna; Montero, Alberto J; Lichtenheld, Mathias G

2013-12-01

CD62L governs the circulation of CD8(+) T cells between lymph nodes and peripheral tissues, whereby the expression of CD62L by CD8(+) T cells promotes their recirculation through lymph nodes. As such, CD62L participates in the fate of adoptively transferred CD8(+) T cells and may control their effectiveness for cancer immunotherapy, including settings in which host preconditioning results in the acute lymphopenia-induced proliferation of the transferred cells. Indeed, previous studies correlated CD62L expression by donor CD8(+) cells with the success rate of adoptive cell therapy (ACT). Here, we analyzed the functions and fate of ex vivo-activated, tumor-specific CD62L(-/-) CD8(+) T cells in a mouse melanoma model for ACT. Unexpectedly, we observed that CD62L(-/-) CD8(+) T cells were functionally indistinguishable from CD62L(+/+) CD8(+) T cells, i.e., both greatly expanded in cyclophosphamide preconditioned animals, controlled subcutaneously and hematogenously spreading tumors, and generated anti-tumor-specific CD8(+) T cell memory. Moreover, even in hosts with rudimentary secondary lymphoid organs (LT(-/-) animals), CD8(+) T cells with and without CD62L expanded equivalently to those adoptively transferred into wild-type animals. These results put into question the utility of CD62L as a predictive biomarker for the efficacy of ex vivo-expanded T cells after ACT in lymphopenic conditions and also offer new insights into the homing, engraftment, and memory generation of adoptively transferred ex vivo-activated CD8(+) T cells.

Suggested Involvement of PP1/PP2A Activity and De Novo Gene Expression in Anhydrobiotic Survival in a Tardigrade, Hypsibius dujardini, by Chemical Genetic Approach.

PubMed

Kondo, Koyuki; Kubo, Takeo; Kunieda, Takekazu

2015-01-01

Upon desiccation, some tardigrades enter an ametabolic dehydrated state called anhydrobiosis and can survive a desiccated environment in this state. For successful transition to anhydrobiosis, some anhydrobiotic tardigrades require pre-incubation under high humidity conditions, a process called preconditioning, prior to exposure to severe desiccation. Although tardigrades are thought to prepare for transition to anhydrobiosis during preconditioning, the molecular mechanisms governing such processes remain unknown. In this study, we used chemical genetic approaches to elucidate the regulatory mechanisms of anhydrobiosis in the anhydrobiotic tardigrade, Hypsibius dujardini. We first demonstrated that inhibition of transcription or translation drastically impaired anhydrobiotic survival, suggesting that de novo gene expression is required for successful transition to anhydrobiosis in this tardigrade. We then screened 81 chemicals and identified 5 chemicals that significantly impaired anhydrobiotic survival after severe desiccation, in contrast to little or no effect on survival after high humidity exposure only. In particular, cantharidic acid, a selective inhibitor of protein phosphatase (PP) 1 and PP2A, exhibited the most profound inhibitory effects. Another PP1/PP2A inhibitor, okadaic acid, also significantly and specifically impaired anhydrobiotic survival, suggesting that PP1/PP2A activity plays an important role for anhydrobiosis in this species. This is, to our knowledge, the first report of the required activities of signaling molecules for desiccation tolerance in tardigrades. The identified inhibitory chemicals could provide novel clues to elucidate the regulatory mechanisms underlying anhydrobiosis in tardigrades.

Suggested Involvement of PP1/PP2A Activity and De Novo Gene Expression in Anhydrobiotic Survival in a Tardigrade, Hypsibius dujardini, by Chemical Genetic Approach

PubMed Central

Kondo, Koyuki; Kubo, Takeo; Kunieda, Takekazu

2015-01-01

Upon desiccation, some tardigrades enter an ametabolic dehydrated state called anhydrobiosis and can survive a desiccated environment in this state. For successful transition to anhydrobiosis, some anhydrobiotic tardigrades require pre-incubation under high humidity conditions, a process called preconditioning, prior to exposure to severe desiccation. Although tardigrades are thought to prepare for transition to anhydrobiosis during preconditioning, the molecular mechanisms governing such processes remain unknown. In this study, we used chemical genetic approaches to elucidate the regulatory mechanisms of anhydrobiosis in the anhydrobiotic tardigrade, Hypsibius dujardini. We first demonstrated that inhibition of transcription or translation drastically impaired anhydrobiotic survival, suggesting that de novo gene expression is required for successful transition to anhydrobiosis in this tardigrade. We then screened 81 chemicals and identified 5 chemicals that significantly impaired anhydrobiotic survival after severe desiccation, in contrast to little or no effect on survival after high humidity exposure only. In particular, cantharidic acid, a selective inhibitor of protein phosphatase (PP) 1 and PP2A, exhibited the most profound inhibitory effects. Another PP1/PP2A inhibitor, okadaic acid, also significantly and specifically impaired anhydrobiotic survival, suggesting that PP1/PP2A activity plays an important role for anhydrobiosis in this species. This is, to our knowledge, the first report of the required activities of signaling molecules for desiccation tolerance in tardigrades. The identified inhibitory chemicals could provide novel clues to elucidate the regulatory mechanisms underlying anhydrobiosis in tardigrades. PMID:26690982

Priming of the Cells: Hypoxic Preconditioning for Stem Cell Therapy.

PubMed

Wei, Zheng Z; Zhu, Yan-Bing; Zhang, James Y; McCrary, Myles R; Wang, Song; Zhang, Yong-Bo; Yu, Shan-Ping; Wei, Ling

2017-10-05

Stem cell-based therapies are promising in regenerative medicine for protecting and repairing damaged brain tissues after injury or in the context of chronic diseases. Hypoxia can induce physiological and pathological responses. A hypoxic insult might act as a double-edged sword, it induces cell death and brain damage, but on the other hand, sublethal hypoxia can trigger an adaptation response called hypoxic preconditioning or hypoxic tolerance that is of immense importance for the survival of cells and tissues. This review was based on articles published in PubMed databases up to August 16, 2017, with the following keywords: "stem cells," "hypoxic preconditioning," "ischemic preconditioning," and "cell transplantation." Original articles and critical reviews on the topics were selected. Hypoxic preconditioning has been investigated as a primary endogenous protective mechanism and possible treatment against ischemic injuries. Many cellular and molecular mechanisms underlying the protective effects of hypoxic preconditioning have been identified. In cell transplantation therapy, hypoxic pretreatment of stem cells and neural progenitors markedly increases the survival and regenerative capabilities of these cells in the host environment, leading to enhanced therapeutic effects in various disease models. Regenerative treatments can mobilize endogenous stem cells for neurogenesis and angiogenesis in the adult brain. Furthermore, transplantation of stem cells/neural progenitors achieves therapeutic benefits via cell replacement and/or increased trophic support. Combinatorial approaches of cell-based therapy with additional strategies such as neuroprotective protocols, anti-inflammatory treatment, and rehabilitation therapy can significantly improve therapeutic benefits. In this review, we will discuss the recent progress regarding cell types and applications in regenerative medicine as well as future applications.

Condition Number Estimation of Preconditioned Matrices

PubMed Central

Kushida, Noriyuki

2015-01-01

The present paper introduces a condition number estimation method for preconditioned matrices. The newly developed method provides reasonable results, while the conventional method which is based on the Lanczos connection gives meaningless results. The Lanczos connection based method provides the condition numbers of coefficient matrices of systems of linear equations with information obtained through the preconditioned conjugate gradient method. Estimating the condition number of preconditioned matrices is sometimes important when describing the effectiveness of new preconditionerers or selecting adequate preconditioners. Operating a preconditioner on a coefficient matrix is the simplest method of estimation. However, this is not possible for large-scale computing, especially if computation is performed on distributed memory parallel computers. This is because, the preconditioned matrices become dense, even if the original matrices are sparse. Although the Lanczos connection method can be used to calculate the condition number of preconditioned matrices, it is not considered to be applicable to large-scale problems because of its weakness with respect to numerical errors. Therefore, we have developed a robust and parallelizable method based on Hager’s method. The feasibility studies are curried out for the diagonal scaling preconditioner and the SSOR preconditioner with a diagonal matrix, a tri-daigonal matrix and Pei’s matrix. As a result, the Lanczos connection method contains around 10% error in the results even with a simple problem. On the other hand, the new method contains negligible errors. In addition, the newly developed method returns reasonable solutions when the Lanczos connection method fails with Pei’s matrix, and matrices generated with the finite element method. PMID:25816331

Metformin Preconditioning of Human induced Pluripotent Stem Cell-derived Neural Stem Cells Promotes Their Engraftment and Improves Post-Stroke Regeneration and Recovery.

PubMed

Ould-Brahim, Fares; Sarma, Sailendra Nath; Syal, Charvi; Lu, Kevin Jiaqi; Seegobin, Matthew; Carter, Anthony; Jeffers, Matthew S; Doré, Carole; Stanford, William; Corbett, Dale; Wang, Jing

2018-06-12

While transplantation of hiPSC-derived neural stem cells (hiPSC-NSCs) shows therapeutic potential in animal stroke models, major concerns for translating hiPSC therapy to the clinic are efficacy and safety. Therefore, there is a demand to develop an optimal strategy to enhance the engraftment and regenerative capacity of transplanted hiPSC-NSCs in order to produce fully differentiated neural cells to replace lost brain tissues. Metformin, an FDA approved drug, is an optimal neuroregenerative agent that not only promotes NSC proliferation but also drives NSC towards differentiation. In this regard, we hypothesize that preconditioning of hiPSC-NSCs with metformin before transplantation into the stroke-damaged brain will improve engraftment and regenerative capabilities of hiPSC-NSCs, ultimately enhancing functional recovery. Here we show that pretreatment of hiPSC-NSCs with metformin enhances the proliferation and differentiation of hiPSC-NSCs in culture. Furthermore, metformin-preconditioned hiPSC-NSCs show increased engraftment 1-week post-transplant in a rat endothelin-1 focal ischemic stroke model. In addition, metformin preconditioned cell grafts exhibit increased survival compared to naïve cell grafts at 7-week post-transplant. Analysis of the grafts demonstrates that metformin preconditioning enhances the differentiation of hiPSC-NSCs. As an outcome, rats receiving metformin preconditioned cells display accelerated gross motor recovery and reduced infarct volume. These studies represent a vital step forward in the optimization of hiPSC-NSC based transplantation to promote post-stroke recovery.

Shared Book Reading Promotes Not Only Language Development, But Also Grapheme Awareness in German Kindergarten Children

PubMed Central

Wesseling, Patricia B. C.; Christmann, Corinna A.; Lachmann, Thomas

2017-01-01

Effects of shared book reading on expressive vocabulary and grapheme awareness without letter instruction in German kindergarteners (longitudinal; N = 69, 3;0–4;8 years) were investigated. Expressive vocabulary was measured by using a standardized test; grapheme awareness was measured by asking children to identify one grapheme per trial presented amongst non-letter distractors. Two methods of shared book reading were investigated, literacy enrichment (additional books) and teacher training in shared book reading strategies, both without explicit letter instruction. Whereas positive effects of shared book reading on expressive vocabulary were evident in numerous previous studies, the impact of shared book reading on grapheme awareness has not yet been investigated. Both methods resulted in positive effects on children’s expressive vocabulary and grapheme awareness over a period of 6 months. Thus, early shared book reading may not only be considered to be a tool for promoting the development of expressive vocabulary, but also for implicit acquisition of grapheme awareness. The latter is considered an important precondition required for the explicit learning of grapheme–phoneme conversion rules (letter knowledge). PMID:28377732

Shared Book Reading Promotes Not Only Language Development, But Also Grapheme Awareness in German Kindergarten Children.

PubMed

Wesseling, Patricia B C; Christmann, Corinna A; Lachmann, Thomas

2017-01-01

Effects of shared book reading on expressive vocabulary and grapheme awareness without letter instruction in German kindergarteners (longitudinal; N = 69, 3;0-4;8 years) were investigated. Expressive vocabulary was measured by using a standardized test; grapheme awareness was measured by asking children to identify one grapheme per trial presented amongst non-letter distractors. Two methods of shared book reading were investigated, literacy enrichment (additional books) and teacher training in shared book reading strategies, both without explicit letter instruction. Whereas positive effects of shared book reading on expressive vocabulary were evident in numerous previous studies, the impact of shared book reading on grapheme awareness has not yet been investigated. Both methods resulted in positive effects on children's expressive vocabulary and grapheme awareness over a period of 6 months. Thus, early shared book reading may not only be considered to be a tool for promoting the development of expressive vocabulary, but also for implicit acquisition of grapheme awareness. The latter is considered an important precondition required for the explicit learning of grapheme-phoneme conversion rules (letter knowledge).

Similar, but different: structurally related azelaic acid and hexanoic acid trigger differential metabolomic and transcriptomic responses in tobacco cells.

PubMed

Djami-Tchatchou, Arnaud T; Ncube, Efficient N; Steenkamp, Paul A; Dubery, Ian A

2017-11-29

Plants respond to various stress stimuli by activating an enhanced broad-spectrum defensive ability. The development of novel resistance inducers represents an attractive, alternative crop protection strategy. In this regard, hexanoic acid (Hxa, a chemical elicitor) and azelaic acid (Aza, a natural signaling compound) have been proposed as inducers of plant defense, by means of a priming mechanism. Here, we investigated both the mode of action and the complementarity of Aza and Hxa as priming agents in Nicotiana tabacum cells in support of enhanced defense. Metabolomic analyses identified signatory biomarkers involved in the establishment of a pre-conditioned state following Aza and Hxa treatment. Both inducers affected the metabolomes in a similar manner and generated common biomarkers: caffeoylputrescine glycoside, cis-5-caffeoylquinic acid, feruloylglycoside, feruloyl-3-methoxytyramine glycoside and feruloyl-3-methoxytyramine conjugate. Subsequently, quantitative real time-PCR was used to investigate the expression of inducible defense response genes: phenylalanine ammonia lyase, hydroxycinnamoyl CoA quinate transferase and hydroxycinnamoyl transferase to monitor activation of the early phenylpropanoid pathway and chlorogenic acids metabolism, while ethylene response element-binding protein, small sar1 GTPase, heat shock protein 90, RAR1, SGT1, non-expressor of PR genes 1 and thioredoxin were analyzed to report on signal transduction events. Pathogenesis-related protein 1a and defensin were quantified to investigate the activation of defenses regulated by salicylic acid and jasmonic acid respectively. The qPCR results revealed differential expression kinetics and, in general (except for NPR1, Thionin and PR1a), the relative gene expression ratios observed in the Hxa-treated cells were significantly greater than the expression observed in the cells treated with Aza. The results indicate that Aza and Hxa have a similar priming effect through activation of genes involved in the establishment of systemic acquired resistance, associated with enhanced synthesis of hydroxycinnamic acids and related conjugates.

Orderings for conjugate gradient preconditionings

NASA Technical Reports Server (NTRS)

Ortega, James M.

1991-01-01

The effect of orderings on the rate of convergence of the conjugate gradient method with SSOR or incomplete Cholesky preconditioning is examined. Some results also are presented that help to explain why red/black ordering gives an inferior rate of convergence.

Anti-inflammatory effects on ischemia/reperfusion-injured lung transplants by the cluster of differentiation 26/dipeptidylpeptidase 4 (CD26/DPP4) inhibitor vildagliptin.

PubMed

Jang, Jae-Hwi; Yamada, Yoshito; Janker, Florian; De Meester, Ingrid; Baerts, Lesley; Vliegen, Gwendolyn; Inci, Ilhan; Chatterjee, Shampa; Weder, Walter; Jungraithmayr, Wolfgang

2017-03-01

We showed previously that stromal cell-derived factor 1 (SDF-1) is a substrate of cluster of differentiation 26/dipeptidylpeptidase 4 (CD26/DPP4) and exerts regenerative properties on acute lung ischemia-reperfusion injury on CD26/DPP4 inhibition. Here, we extend our studies to test whether an intermediate recovery of lung transplants from ischemia/reperfusion injury by CD26/DPP4 inhibition can be achieved for up to 14 days. Syngeneic mouse lung transplantation (Tx) was performed in C57BL/6 and in CD26-/- mice by applying 18 hours of cold ischemia. Donor lungs were preconditioned with saline or the CD26/DPP4 inhibitor vildagliptin (1 μg/mL [3 μM]). In vitro, the influence of vildagliptin and SDF-1 on the macrophage cell line RAW 264.7 was tested. Transplants were analyzed up to 14 days after Tx for the expression of SDF-1, tumor necrosis factor-α (TNF-α), interleukin-10, intercellular adhesion molecule-1 (ICAM-1), immune cell infiltration, and oxygenation. Cold ischemic time of 18 hours with vildagliptin preconditioning elevated lung SDF-1 levels (P = .0011) and increased interleukin-10-producing macrophages (P = .0165) compared with the control. SDF-1 reduced macrophage-derived TNF-α (P = .0248) in vitro. Five hours after Tx, vildagliptin significantly reduced macrophages and neutrophils (P = .0306), decreased ICAM-1 expression (P = .002), and improved transplant oxygenation (P = .0181). Seven days after Tx, grafts were preserved on CD26/DPP4-inhibition: perivascular macrophages (P = .0046) and TNF-α (P = .0013) were reduced as well as T and B cells. ICAM-1 was absent in CD26/DPP4-inhibited grafts at all time points. This study proves an intermediate improvement of ischemia/reperfusion-injured lung transplants by the CD26/DPP4-inhibitor vildagliptin up to 14 days. Enhanced levels of SDF-1 induced an anti-inflammatory effect on a cellular and protein level, and render CD26/DPP4 inhibition preconditioning effective for the protection from lung ischemia/reperfusion injury. Copyright © 2016 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

Interactions of dietary protein and carbohydrate determine blood sugar level and regulate nutrient selection in the insect Manduca sexta L.

PubMed

Thompson, S N; Redak, R A

2000-09-01

The non-homeostatic regulation of blood sugar concentration in the insect Manduca sexta L. was affected by nutritional status. Larvae maintained on diets lacking sucrose displayed low concentrations of trehalose, the blood sugar of insects, which varied from 5 to 15 mM with increasing dietary casein level between 12.5 and 75 g/l. These insects were glucogenic, as demonstrated by the selective 13C enrichment of trehalose synthesized from [3-13C]alanine, and de novo synthesis was the sole source of blood sugar. The distribution of 13C in glutamine established that following transamination of the 13C substituted substrate, [3-13C]pyruvate carboxylation rather than decarboxylation was the principal pathway of Pyr metabolism. The mean blood trehalose level was higher in insects maintained on diets with sucrose. At the lowest dietary casein level blood trehalose was approximately 50 mM, and declined to 20 mM at the highest casein level. Gluconeogenesis was detected in insects maintained on sucrose-free diets at the higher protein levels examined, but [3-13C]pyruvate decarboxylation and TCA cycle metabolism was the principal fate of [3-13C]alanine following transamination, and dietary carbohydrate was the principal source of glucose for trehalose synthesis. Feeding studies established a relationship between nutritional status, blood sugar level and dietary self-selection. Insects preconditioned by feeding on diets without sucrose had low blood sugar levels regardless of dietary casein level, and when subsequently given a choice between a sucrose diet or a casein diet, selected the former. Larvae preconditioned on a diet containing sucrose and the lowest level of casein had high blood sugar levels and subsequently selected the casein diet. Larvae maintained on the sucrose diet with the highest casein level had low blood sugar and self-selected the sucrose diet. When preconditioned on diets with sucrose and intermediate levels of casein, insects selected more equally between the sucrose and the casein diets. It is concluded that blood sugar level may be intimately involved in dietary self-selection by M. sexta larvae, and that in the absence of dietary carbohydrate, gluconeogenesis provides sufficient blood sugar to ensure that larvae choose a diet or diets that produce an optimal intake of dietary protein and carbohydrate.

Preconditioning by inhaled nitric oxide prevents hyperoxic and ischemia/reperfusion injury in rat lungs.

PubMed

Waldow, Thomas; Witt, Wolfgang; Ulmer, André; Janke, Andreas; Alexiou, Konstantin; Matschke, Klaus

2008-01-01

Since the generation of nitric oxide (NO) is an essential step in the trigger phase of ischemic preconditioning, short-term inhalation of NO before ischemia should ameliorate ischemia/reperfusion (I/R) injury of the lung. We tested this hypothesis in high oxygen (>99%) ventilated rats in order to additionally evaluate compatibility of NO and exposure to hyperoxia. Male adult Sprague-Dawley rats inhaled NO (15 ppm, 10 min) before the left lung hilum was clamped for 1 h, and the reperfusion phase was observed for 4 h (NO group). Animals in the I/R group underwent the same treatment, but without NO inhalation. A third group without I/R served as time-matched controls. Animals in the I/R group showed severe I/R injury in terms of arterial pO2 (apO2), which was reduced to 22% of surgical controls (SCs) at time point 30 min reperfusion, and increased endothelial permeability (Evans blue procedure). The pretreatment with NO attenuated these effects. The pO2 after 4 h reperfusion was still 3.0-fold higher in the NO group compared to I/R. In contrast, the I/R- and hyperoxia-induced invasion of leukocytes, as determined by measuring myeloperoxidase (MPO) activity, was not affected by NO. These data were correlated with the activity of major cellular signaling pathways by measuring the phosphorylation at activating and inhibitory sites of extracellular-signal regulated kinase (ERK), c-Jun N-terminal kinase (JNK), p38, protein kinase B (AKT), and glycogen synthase kinase 3beta (GSK-3beta), and by determination of cGMP in plasma and lung tissue. Inhalation of NO partly prevented the loss of activation by I/R and hyperoxic ventilation of ERK, JNK, and AKT, and it reduced the I/R-induced activation of GSK-3beta. The level of cGMP in plasma and lung tissue was increased in the NO group after 4 h reperfusion. In conclusion, application of inhaled NO in the preconditioning mode prevented I/R injury in the rat lung without interfering effects of hyperoxic ventilation. The effects of NO on cellular signaling pathways resemble mechanisms of ischemic preconditioning, but further studies have to evaluate the physiological relevance of these results.

Neuroprotective Effect of Antioxidants and Moderate Hypoxia as Combined Preconditioning in Cerebral Ischemia.

PubMed

Levchenkova, O S; Novikov, V E; Parfenov, E A; Kulagin, K N

2016-12-01

We studied combined effect of moderate hypoxia and compounds pQ-4, pQ-915, pQ-1032, and pQ-1104 on neurological deficit and survival of rats after bilateral ligation of common carotid arteries. Preconditioning including moderate hypoxia and treatment with compound pQ-4 produced a neuroprotective effect and increased animal survival during the early (by 51%) and late (by 33.5%) periods of modeled ischemia and reduced neurological deficit (by 50% and 41%, respectively). Moreover, this combination of preconditioning factors prevented postischemic excessive activation of free radical oxidation in brain hemispheres and blood serum.

[Effects of xenon preconditioning against ischemia/reperfusion injury and oxidative stress in immature heart].

PubMed

Li, Qian; Lian, Chun-Wei; Fang, Li-Qun; Liu, Bin; Yang, Bo

2014-09-01

To investigate whether xenon preconditioning (PC) could protect immature myocardium against ischemia-reperfusion (I/R) injury in a dose-dependent manner and clarify the role of xenon PC on oxidative stress. Forty-eight isolated perfused immature rabbit hearts were randomly divided into four groups (n = 12): The sham group had the hearts perfused continuously for 300 min. In I/R group, the hearts were subjected to 60 min perfusion followed by 60 min ischemia and 180 min reperfusion. In 1 minimum alveolar concentration (MAC) and 0.5 MAC xenon PC groups, the hearts were preconditioned with 1 MAC or 0.5 MAC xenon respectively, following 60 min ischemia and 180 min reperfusion. The cardiac function, myocardial infarct size, mitochondrial structure, superoxide dismutase (SOD) activity and malondialdehyde (MDA) level in each group were determined after reperfusion. Compared with I/R group, both 1 MAC and 0. 5 MAC xenon preconditioning significantly improved cardiac function (P < 0.01), reduced myocardial infarct size (P < 0.01) and mitochondrial damage, increased SOD activity and decreased MDA level (P < 0.01). There were no differences between 1 MAC group and 0.5 MAC xenon group (P > 0.05). Xenon preconditioning at 0. 5 and 1 MAC produce similar cardioprotective effects against I/R injury in isolated perfused immature heart.

Reducing pulmonary injury by hyperbaric oxygen preconditioning during simulated high altitude exposure in rats.

PubMed

Li, Zhuo; Gao, Chunjin; Wang, Yanxue; Liu, Fujia; Ma, Linlin; Deng, Changlei; Niu, Ko-Chi; Lin, Mao-Tsun; Wang, Chen

2011-09-01

Hyperbaric oxygen preconditioning (HBO₂P + HAE) has been found to be beneficial in preventing the occurrence of ischemic damage to brain, spinal cord, heart, and liver in several disease models. In addition, pulmonary inflammation and edema are associated with a marked reduction in the expression levels of both aquaporin (AQP) 1 and AQP5 in the lung. Here, the aims of this study are first to ascertain whether acute lung injury can be induced by simulated high altitude in rats and second to assess whether HBO2P + HAE is able to prevent the occurrence of the proposed high altitude-induced ALI. Rats were randomly divided into the following three groups: the normobaric air (NBA; 21% O₂ at 1 ATA) group, the HBO₂P + high altitude exposure (HAE) group, and the NBA + HAE group. In HBO₂P + HAE group, animals received 100% O₂ at 2.0 ATA for 1 hour per day, for five consecutive days. In HAE groups, animals were exposed to a simulated HAE of 6,000 m in a hypobaric chamber for 24 hours. Right after being taken out to the ambient, animals were anesthetized generally and killed and thoroughly exsanguinated before their lungs were excised en bloc. The lungs were used for both histologic and molecular evaluation and analysis. In NBA + HAE group, the animals displayed higher scores of alveolar edema, neutrophil infiltration, and hemorrhage compared with those of NBA controls. In contrast, the levels of both AQP1 and AQP5 proteins and mRNA expression in the lung in the NBA + HAE group were significantly lower than those of NBA controls. However, the increased lung injury scores and the decreased levels of both AQP1 and AQP5 proteins and mRNA expression in the lung caused by HAE was significantly reduced by HBO₂P + HAE. Our results suggest that high altitude pulmonary injury may be prevented by HBO2P + HAE in rats.

Remote Ischaemic Preconditioning and Sevoflurane Postconditioning Synergistically Protect Rats from Myocardial Injury Induced by Ischemia and Reperfusion Partly via Inhibition TLR4/MyD88/NF-κB Signaling Pathway.

PubMed

Zhang, Jiru; Zhang, Jing; Yu, Peng; Chen, Min; Peng, Qingfeng; Wang, Zhiqiang; Dong, Nan

2017-01-01

A combination sevoflurane postconditioning (SPC) and remote ischemic preconditioning (RIPC) is proved effective in an ex vivo rat heart perfusion model. However, the combined effect of those two interventions is not tested in rat myocardial ischemia/reperfusion (I/R) model, and the underlying mechanisms remain to be elucidated. This study aimed to investigate the effect in vivo using a rat myocardial I/R model and illuminate the related mechanisms. Forty male Sprague-Dawley rats were randomly divided into the following 5 groups: i) sham-operated control; ii) I/R; iii) I/R + RIPC; iv) I/R + SPC; v) I/R + RIPC + SPC. The hemodynamic parameters were recorded at the end of reperfusion. The histological changes including the infarct size were assessed using Triphenyltetrazolium chloride (TTC) staining and H&E staining. In addition, the circulating levels of cardiac enzymes (CK-MB, hs-cTnT, and cTnT) inflammatory cytokines (IL-6, IL-8, and TNF-α) were detected. The expression levels of apoptosis-related proteins (C-Caspase 3, PARP, Bax, and Bcl-2), proinflammatory factors (TLR4, HMGB-1, MyD88, and p65), and IKB-α were measured by Western blot analysis. Real-time PCR was performed to detect mRNA levels of the proinflammatory factors. Both SPC and RIPC significantly reduced the infarct size, cardiac enzyme release, inflammatory cytokine secretion, and proinflammatory factor expression, and increased IKB-α expression compared to I/R group. Furthermore, the combination of those two strategies had synergic infarct size limiting and anti-inflammatory effects. The finding of this study suggested that the combination of SPC and RIPC had a potentially cardioprotective effect through inhibiting TLR4/MyD88/NF-κB signaling. © 2017 The Author(s) Published by S. Karger AG, Basel.

Exploring the Human Plasma Proteome for Humoral Mediators of Remote Ischemic Preconditioning - A Word of Caution

PubMed Central

Helgeland, Erik; Breivik, Lars Ertesvåg; Vaudel, Marc; Svendsen, Øyvind Sverre; Garberg, Hilde; Nordrehaug, Jan Erik; Berven, Frode Steingrimsen; Jonassen, Anne Kristine

2014-01-01

Despite major advances in early revascularization techniques, cardiovascular diseases are still the leading cause of death worldwide, and myocardial infarctions contribute heavily to this. Over the past decades, it has become apparent that reperfusion of blood to a previously ischemic area of the heart causes damage in and of itself, and that this ischemia reperfusion induced injury can be reduced by up to 50% by mechanical manipulation of the blood flow to the heart. The recent discovery of remote ischemic preconditioning (RIPC) provides a non-invasive approach of inducing this cardioprotection at a distance. Finding its endogenous mediators and their operative mode is an important step toward increasing the ischemic tolerance. The release of humoral factor(s) upon RIPC was recently demonstrated and several candidate proteins were published as possible mediators of the cardioprotection. Before clinical applicability, these potential biomarkers and their efficiency must be validated, a task made challenging by the large heterogeneity in reported data and results. Here, in an attempt to reproduce and provide more experimental data on these mediators, we conducted an unbiased in-depth analysis of the human plasma proteome before and after RIPC. From the 68 protein markers reported in the literature, only 28 could be mapped to manually reviewed (Swiss-Prot) protein sequences. 23 of them were monitored in our untargeted experiment. However, their significant regulation could not be reproducibly estimated. In fact, among the 394 plasma proteins we accurately quantified, no significant regulation could be confidently and reproducibly assessed. This indicates that it is difficult to both monitor and reproduce published data from experiments exploring for RIPC induced plasma proteomic regulations, and suggests that further work should be directed towards small humoral factors. To simplify this task, we made our proteomic dataset available via ProteomeXchange, where scientists can mine for novel potential targets. PMID:25333471

40 CFR 1066.407 - Vehicle preparation and preconditioning.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 34 2012-07-01 2012-07-01 false Vehicle preparation and...) AIR POLLUTION CONTROLS VEHICLE-TESTING PROCEDURES Vehicle Preparation and Running a Test § 1066.407 Vehicle preparation and preconditioning. This section describes steps to take before measuring exhaust...

40 CFR 1066.407 - Vehicle preparation and preconditioning.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 34 2013-07-01 2013-07-01 false Vehicle preparation and...) AIR POLLUTION CONTROLS VEHICLE-TESTING PROCEDURES Vehicle Preparation and Running a Test § 1066.407 Vehicle preparation and preconditioning. This section describes steps to take before measuring exhaust...

Expression profiling and cross-species RNA interference (RNAi) of desiccation-induced transcripts in the anhydrobiotic nematode Aphelenchus avenae

PubMed Central

2010-01-01

Background Some organisms can survive extreme desiccation by entering a state of suspended animation known as anhydrobiosis. The free-living mycophagous nematode Aphelenchus avenae can be induced to enter anhydrobiosis by pre-exposure to moderate reductions in relative humidity (RH) prior to extreme desiccation. This preconditioning phase is thought to allow modification of the transcriptome by activation of genes required for desiccation tolerance. Results To identify such genes, a panel of expressed sequence tags (ESTs) enriched for sequences upregulated in A. avenae during preconditioning was created. A subset of 30 genes with significant matches in databases, together with a number of apparently novel sequences, were chosen for further study. Several of the recognisable genes are associated with water stress, encoding, for example, two new hydrophilic proteins related to the late embryogenesis abundant (LEA) protein family. Expression studies confirmed EST panel members to be upregulated by evaporative water loss, and the majority of genes was also induced by osmotic stress and cold, but rather fewer by heat. We attempted to use RNA interference (RNAi) to demonstrate the importance of this gene set for anhydrobiosis, but found A. avenae to be recalcitrant with the techniques used. Instead, therefore, we developed a cross-species RNAi procedure using A. avenae sequences in another anhydrobiotic nematode, Panagrolaimus superbus, which is amenable to gene silencing. Of 20 A. avenae ESTs screened, a significant reduction in survival of desiccation in treated P. superbus populations was observed with two sequences, one of which was novel, while the other encoded a glutathione peroxidase. To confirm a role for glutathione peroxidases in anhydrobiosis, RNAi with cognate sequences from P. superbus was performed and was also shown to reduce desiccation tolerance in this species. Conclusions This study has identified and characterised the expression profiles of members of the anhydrobiotic gene set in A. avenae. It also demonstrates the potential of RNAi for the analysis of anhydrobiosis and provides the first genetic data to underline the importance of effective antioxidant systems in metazoan desiccation tolerance. PMID:20085654

Lessons from the Clinton plan: incremental market reform, not sweeping government control.

PubMed

Antos, Joseph

2008-01-01

The Clinton health reform attempt in the mid-1990s and the U.S. experience since then suggest some clear lessons for the next U.S. president. Public confidence in a major reform proposal must be won, and congressional support must be garnered, even if the election is a landslide. Insisting on universal coverage as a precondition may undercut the ability to enact other policies needed to improve the health system. Excessive regulation and price controls are likely to exacerbate underlying problems. The next president should take full advantage of market incentives to promote a high-value health system.

[Can tobacco companies be good corporate citizens?].

PubMed

Palazzo, G; Mena, S

2009-07-01

Tobacco companies have jumped on the Corporate social responsibility (CSR) bandwagon as a tentative to be societally accepted as responsible actors and good corporate citizens. This is however not possible for two reasons. First, the product they sell is lethal and thus not compatible with the precondition of doing no harm to be a good corporate citizen. Second, the behavior of tobacco firms is not responsible, being illustrated by four examples: junk science versus sound science strategy, seducing young smokers, political lobbying and getting customers on new markets. To conclude, three implications for regulating the activities of the tobacco industry are given.

Priming of the Cells: Hypoxic Preconditioning for Stem Cell Therapy

PubMed Central

Wei, Zheng Z; Zhu, Yan-Bing; Zhang, James Y; McCrary, Myles R; Wang, Song; Zhang, Yong-Bo; Yu, Shan-Ping; Wei, Ling

2017-01-01

Objective: Stem cell-based therapies are promising in regenerative medicine for protecting and repairing damaged brain tissues after injury or in the context of chronic diseases. Hypoxia can induce physiological and pathological responses. A hypoxic insult might act as a double-edged sword, it induces cell death and brain damage, but on the other hand, sublethal hypoxia can trigger an adaptation response called hypoxic preconditioning or hypoxic tolerance that is of immense importance for the survival of cells and tissues. Data Sources: This review was based on articles published in PubMed databases up to August 16, 2017, with the following keywords: “stem cells,” “hypoxic preconditioning,” “ischemic preconditioning,” and “cell transplantation.” Study Selection: Original articles and critical reviews on the topics were selected. Results: Hypoxic preconditioning has been investigated as a primary endogenous protective mechanism and possible treatment against ischemic injuries. Many cellular and molecular mechanisms underlying the protective effects of hypoxic preconditioning have been identified. Conclusions: In cell transplantation therapy, hypoxic pretreatment of stem cells and neural progenitors markedly increases the survival and regenerative capabilities of these cells in the host environment, leading to enhanced therapeutic effects in various disease models. Regenerative treatments can mobilize endogenous stem cells for neurogenesis and angiogenesis in the adult brain. Furthermore, transplantation of stem cells/neural progenitors achieves therapeutic benefits via cell replacement and/or increased trophic support. Combinatorial approaches of cell-based therapy with additional strategies such as neuroprotective protocols, anti-inflammatory treatment, and rehabilitation therapy can significantly improve therapeutic benefits. In this review, we will discuss the recent progress regarding cell types and applications in regenerative medicine as well as future applications. PMID:28937044

Anti-inflammatory and antioxidant effects of polyphenols extracted from Antirhea borbonica medicinal plant on adipocytes exposed to Porphyromonas gingivalis and Escherichia coli lipopolysaccharides.

PubMed

Le Sage, Fanny; Meilhac, Olivier; Gonthier, Marie-Paule

2017-05-01

In obesity, gut microbiota LPS may translocate into the blood stream and then contribute to adipose tissue inflammation and oxidative stress, leading to insulin resistance. A causal link between periodontal infection, obesity and type 2 diabetes has also been suggested. We evaluated the ability of polyphenols from Antirhea borbonica medicinal plant to improve the inflammatory and redox status of 3T3-L1 adipocytes exposed to LPS of Porphyromonas gingivalis periodontopathogen or Escherichia coli enterobacteria. Our results show that LPS enhanced the production of Toll-like receptor-dependent MyD88 and NFκB signaling factors as well as IL-6, MCP-1, PAI-1 and resistin. Plant polyphenols reduced LPS pro-inflammatory action. Concomitantly, polyphenols increased the production of adiponectin and PPARγ, known as key anti-inflammatory and insulin-sensitizing mediators. Moreover, both LPS increased intracellular ROS levels and the expression of genes encoding ROS-producing enzymes including NOX2, NOX4 and iNOS. Plant polyphenols reversed these effects and up-regulated MnSOD and catalase antioxidant enzyme gene expression. Noticeably, preconditioning of cells with caffeic acid, chlorogenic acid or kaempferol identified among A. borbonica major polyphenols, led to similar protective properties. Altogether, these findings demonstrate the anti-inflammatory and antioxidant effects of A. borbonica polyphenols on adipocytes, in response to P. gingivalis or E. coli LPS. It will be of major interest to assess A. borbonica polyphenol benefits against obesity-related metabolic disorders such as insulin resistance in vivo. Copyright © 2017 Elsevier Ltd. All rights reserved.

Progesterone resistance in endometriosis: origins, consequences and interventions.

PubMed

Patel, Bansari G; Rudnicki, Martin; Yu, Jie; Shu, Yimin; Taylor, Robert N

2017-06-01

Endometriosis is a common cause of pelvic pain and affects up to 10% of women of reproductive age. Aberrant progesterone signaling in the endometrium plays a significant role in impaired decidualization and establishment of ectopic endometrial implants. Eutopic endometrial cells from women with endometriosis fail to downregulate genes needed for decidualization, such as those involved in cell cycle regulation, leading to unbridled proliferation. Several causes of progesterone resistance in the endometrium have been postulated, including congenital "preconditioning", whereby the in utero environment renders infants susceptible to neonatal uterine bleeding and endometriosis. Progesterone action is crucial to decreasing inflammation in the endometrium, and deviant progesterone signaling results in a proinflammatory phenotype. Conversely, chronic inflammation can induce a progesterone-resistant state. Repetitive retrograde endometrial shedding begets chronic peritoneal inflammation, which further exacerbates progesterone resistance. Genetic causes of progesterone resistance include progesterone receptor gene polymorphisms, altered microRNA expression, and epigenetic modifications to progesterone receptors and their targets. Environmental toxins such as dioxin play a possible role in the genesis of endometriosis by permitting an inflammatory milieu. A consequence of impaired progesterone action is that hormonal therapy is rendered ineffective for a subset of women with endometriosis. Synthetic progestins, such as dienogest, may overcome this phenomenon by increasing progesterone receptor expression and decreasing proinflammatory cytokines. Other modalities include high dose depot formulations of progestins, medicated intrauterine devices and the likely advent of oral GnRH antagonists. Unearthing root causes of progesterone inaction in endometriosis will aid in the development of novel therapeutics geared toward prevention and treatment. © 2017 Nordic Federation of Societies of Obstetrics and Gynecology.

Toward Gene Therapy for Cystic Fibrosis Using a Lentivirus Pseudotyped With Sendai Virus Envelopes

PubMed Central

Mitomo, Katsuyuki; Griesenbach, Uta; Inoue, Makoto; Somerton, Lucinda; Meng, Cuixiang; Akiba, Eiji; Tabata, Toshiaki; Ueda, Yasuji; Frankel, Gad M; Farley, Raymond; Singh, Charanjit; Chan, Mario; Munkonge, Felix; Brum, Andrea; Xenariou, Stefania; Escudero-Garcia, Sara; Hasegawa, Mamoru; Alton, Eric WFW

2010-01-01

Gene therapy for cystic fibrosis (CF) is making encouraging progress into clinical trials. However, further improvements in transduction efficiency are desired. To develop a novel gene transfer vector that is improved and truly effective for CF gene therapy, a simian immunodeficiency virus (SIV) was pseudotyped with envelope proteins from Sendai virus (SeV), which is known to efficiently transduce unconditioned airway epithelial cells from the apical side. This novel vector was evaluated in mice in vivo and in vitro directed toward CF gene therapy. Here, we show that (i) we can produce relevant titers of an SIV vector pseudotyped with SeV envelope proteins for in vivo use, (ii) this vector can transduce the respiratory epithelium of the murine nose in vivo at levels that may be relevant for clinical benefit in CF, (iii) this can be achieved in a single formulation, and without the need for preconditioning, (iv) expression can last for 15 months, (v) readministration is feasible, (vi) the vector can transduce human air–liquid interface (ALI) cultures, and (vii) functional CF transmembrane conductance regulator (CFTR) chloride channels can be generated in vitro. Our data suggest that this lentiviral vector may provide a step change in airway transduction efficiency relevant to a clinical programme of gene therapy for CF. PMID:20332767

40 CFR 86.132-00 - Vehicle preconditioning.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 18 2010-07-01 2010-07-01 false Vehicle preconditioning. 86.132-00 Section 86.132-00 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS...] (iii) If a manufacturer has concerns about fuel effects on adaptive memory systems, a manufacturer may...

40 CFR 86.1232-96 - Vehicle preconditioning.

Code of Federal Regulations, 2011 CFR

2011-07-01

... preconditioned separately. If production evaporative canisters are equipped with a functional service port... production evaporative canisters are equipped with a functional service port designed for vapor load or purge... provides at least a 4:1 safety factor against the lean flammability limit. (iii) The FID hydrocarbon...

40 CFR 92.125 - Pre-test procedures and preconditioning.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 21 2012-07-01 2012-07-01 false Pre-test procedures and... PROGRAMS (CONTINUED) CONTROL OF AIR POLLUTION FROM LOCOMOTIVES AND LOCOMOTIVE ENGINES Test Procedures § 92.125 Pre-test procedures and preconditioning. (a) Locomotive testing. (1) Determine engine lubricating...

40 CFR 92.125 - Pre-test procedures and preconditioning.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Pre-test procedures and... PROGRAMS (CONTINUED) CONTROL OF AIR POLLUTION FROM LOCOMOTIVES AND LOCOMOTIVE ENGINES Test Procedures § 92.125 Pre-test procedures and preconditioning. (a) Locomotive testing. (1) Determine engine lubricating...

40 CFR 92.125 - Pre-test procedures and preconditioning.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 20 2011-07-01 2011-07-01 false Pre-test procedures and... PROGRAMS (CONTINUED) CONTROL OF AIR POLLUTION FROM LOCOMOTIVES AND LOCOMOTIVE ENGINES Test Procedures § 92.125 Pre-test procedures and preconditioning. (a) Locomotive testing. (1) Determine engine lubricating...

40 CFR 92.125 - Pre-test procedures and preconditioning.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 21 2013-07-01 2013-07-01 false Pre-test procedures and... PROGRAMS (CONTINUED) CONTROL OF AIR POLLUTION FROM LOCOMOTIVES AND LOCOMOTIVE ENGINES Test Procedures § 92.125 Pre-test procedures and preconditioning. (a) Locomotive testing. (1) Determine engine lubricating...

Ontario's daily physical activity policy for elementary schools: is everything in place for success?

PubMed

Robertson-Wilson, Jennifer E; Lévesque, Lucie

2009-01-01

The development, implementation, and evaluation of policies may play an important role in promoting health behaviours such as physical activity. The Ontario Ministry of Education (OME) recently mandated Memorandum No. 138 requiring daily physical activity (DPA) for Ontario elementary students in grades one through eight. The purpose of this paper is to examine implementation strategies. Hogwood and Gunn's 10 preconditions for "perfect implementation" are used to examine publicly available Ministry DPA policy documents to assess whether these implementation strategies have been considered in the policy documents. Several preconditions (e.g., allocation of resources, task specification) appear to have been considered, however a number of preconditions (e.g., the sustainability of resources, extent to which the policy is valued, and evaluation plans) thought to be important require additional attention to ensure optimal DPA implementation. Additional reflection upon Hogwood and Gunn's implementation preconditions would, in our opinion, assist in facilitating optimal DPA implementation as per Memorandum No. 138.

Silymarin and its constituents in cardiac preconditioning.

PubMed

Zholobenko, A; Modriansky, M

2014-09-01

Silymarin, a standardised extract of Silybum marianum (milk thistle), comprises mainly of silybin, with dehydrosilybin (DHSB), quercetin, taxifolin, silychristin and a number of other compounds which are known to possess a range of salutary effects. Indeed, there is evidence for their role in reducing tumour growth, preventing liver toxicity, and protecting a number of organs against ischemic damage. The hepatoprotective effects of silymarin, especially in preventing Amanita and alcohol intoxication induced damage to the liver, are a well established fact. Likewise, there is weighty evidence that silymarin possesses antimicrobial and anticancer activities. Additionally, it has emerged that in animal models, silymarin can protect the heart, brain, liver and kidneys against ischemia reperfusion injury, probably by preconditioning. The mechanisms of preconditioning are, in general, well studied, especially in the heart. On the other hand, the mechanism by which silymarin protects the heart from ischemia remains largely unexplored. This review, therefore, focuses on evaluating existing studies on silymarin induced cardioprotection in the context of the established mechanisms of preconditioning. Copyright © 2014. Published by Elsevier B.V.

Liquid hydrogen turbopump rapid start program. [thermal preconditioning using coatings

NASA Technical Reports Server (NTRS)

Wong, G. S.

1973-01-01

This program was to analyze, test, and evaluate methods of achieving rapid-start of a liquid hydrogen feed system (inlet duct and turbopump) using a minimum of thermal preconditioning time and propellant. The program was divided into four tasks. Task 1 includes analytical studies of the testing conducted in the other three tasks. Task 2 describes the results from laboratory testing of coating samples and the successful adherence of a KX-635 coating to the internal surfaces of the feed system tested in Task 4. Task 3 presents results of testing an uncoated feed system. Tank pressure was varied to determine the effect of flowrate on preconditioning. The discharge volume and the discharge pressure which initiates opening of the discharge valve were varied to determine the effect on deadhead (no through-flow) start transients. Task 4 describes results of testing a similar, internally coated feed system and illustrates the savings in preconditioning time and propellant resulting from the coatings.

On polynomial preconditioning for indefinite Hermitian matrices

NASA Technical Reports Server (NTRS)

Freund, Roland W.

1989-01-01

The minimal residual method is studied combined with polynomial preconditioning for solving large linear systems (Ax = b) with indefinite Hermitian coefficient matrices (A). The standard approach for choosing the polynomial preconditioners leads to preconditioned systems which are positive definite. Here, a different strategy is studied which leaves the preconditioned coefficient matrix indefinite. More precisely, the polynomial preconditioner is designed to cluster the positive, resp. negative eigenvalues of A around 1, resp. around some negative constant. In particular, it is shown that such indefinite polynomial preconditioners can be obtained as the optimal solutions of a certain two parameter family of Chebyshev approximation problems. Some basic results are established for these approximation problems and a Remez type algorithm is sketched for their numerical solution. The problem of selecting the parameters such that the resulting indefinite polynomial preconditioners speeds up the convergence of minimal residual method optimally is also addressed. An approach is proposed based on the concept of asymptotic convergence factors. Finally, some numerical examples of indefinite polynomial preconditioners are given.

Peri-operative anaesthetic myocardial preconditioning and protection – cellular mechanisms and clinical relevance in cardiac anaesthesia

PubMed Central

Kunst, G; Klein, A A

2015-01-01

Preconditioning has been shown to reduce myocardial damage caused by ischaemia–reperfusion injury peri-operatively. Volatile anaesthetic agents have the potential to provide myocardial protection by anaesthetic preconditioning and, in addition, they also mediate renal and cerebral protection. A number of proof-of-concept trials have confirmed that the experimental evidence can be translated into clinical practice with regard to postoperative markers of myocardial injury; however, this effect has not been ubiquitous. The clinical trials published to date have also been too small to investigate clinical outcome and mortality. Data from recent meta-analyses in cardiac anaesthesia are also not conclusive regarding intra-operative volatile anaesthesia. These inconclusive clinical results have led to great variability currently in the type of anaesthetic agent used during cardiac surgery. This review summarises experimentally proposed mechanisms of anaesthetic preconditioning, and assesses randomised controlled clinical trials in cardiac anaesthesia that have been aimed at translating experimental results into the clinical setting. PMID:25764404

The Kallikrein-Kinin System as a Regulator of Cardiovascular and Renal Function

PubMed Central

Rhaleb, Nour-Eddine; Yang, Xiao-Ping; Carretero, Oscar A.

2015-01-01

Autocrine, paracrine, endocrine, and neuroendocrine hormonal systems help regulate cardiovascular and renal function. Any change in the balance among these systems may result in hypertension and target organ damage, whether the cause is genetic, environmental or a combination of the two. Endocrine and neuroendocrine vasopressor hormones such as the renin-angiotensin system (RAS), aldosterone, and catecholamines are important for regulation of blood pressure and pathogenesis of hypertension and target organ damage. While the role of vasodepressor autacoids such as kinins is not as well defined, there is increasing evidence that they are not only critical to blood pressure and renal function but may also oppose remodeling of the cardiovascular system. Here we will primarily be concerned with kinins, which are oligopeptides containing the aminoacid sequence of bradykinin. They are generated from precursors known as kininogens by enzymes such as tissue (glandular) and plasma kallikrein. Some of the effects of kinins are mediated via autacoids such as eicosanoids, nitric oxide (NO), endothelium-derived hyperpolarizing factor (EDHF), and/or tissue plasminogen activator (†PA). Kinins help protect against cardiac ischemia and play an important part in preconditioning as well as the cardiovascular and renal protective effects of angiotensin-converting enzyme (ACE) and angiotensin type 1 receptor blockers (ARB). But the role of kinins in the pathogenesis of hypertension remains controversial. A study of Utah families revealed that a dominant kallikrein gene expressed as high urinary kallikrein excretion was associated with a decreased risk of essential hypertension. Moreover, researchers have identified a restriction fragment length polymorphism (RFLP) that distinguishes the kallikrein gene family found in one strain of spontaneously hypertensive rats (SHR) from a homologous gene in normotensive Brown Norway rats, and in recombinant inbred substrains derived from these SHR and Brown Norway rats this RFLP cosegregated with an increase in blood pressure. However, humans, rats and mice with a deficiency in one or more components of the kallikrein-kinin-system (KKS) or chronic KKS blockade do not have hypertension. In the kidney, kinins are essential for proper regulation of papillary blood flow and water and sodium excretion. B2-KO mice appear to be more sensitive to the hypertensinogenic effect of salt. Kinins are involved in the acute antihypertensive effects of ACE inhibitors but not their chronic effects (save for mineralocorticoidsalt-induced hypertension). Kinins appear to play a role in the pathogenesis of inflammatory diseases such as arthritis and skin inflammation; they act on innate immunity as mediators of inflammation by promoting maturation of dendritic cells, which activate the body’s adaptive immune system and thereby stimulate mechanisms that promote inflammation. On the other hand, kinins acting via NO contribute to the vascular protective effect of ACE inhibitors during neointima formation. In myocardial infarction produced by ischemia/reperfusion, kinins help reduce infarct size following preconditioning or treatment with ACE inhibitors. In heart failure secondary to infarction, the therapeutic effects of ACE inhibitors are partially mediated by kinins via release of NO, while drugs that activate the angiotensin type 2 receptor act in part via kinins and NO. Thus kinins play an important role in regulation of cardiovascular and renal function as well as many of the beneficial effects of ACE inhibitors and ARBs on target organ damage in hypertension. PMID:23737209

Remote Ischemic Preconditioning and Outcomes of Cardiac Surgery.

PubMed

Hausenloy, Derek J; Candilio, Luciano; Evans, Richard; Ariti, Cono; Jenkins, David P; Kolvekar, Shyam; Knight, Rosemary; Kunst, Gudrun; Laing, Christopher; Nicholas, Jennifer; Pepper, John; Robertson, Steven; Xenou, Maria; Clayton, Tim; Yellon, Derek M

2015-10-08

Whether remote ischemic preconditioning (transient ischemia and reperfusion of the arm) can improve clinical outcomes in patients undergoing coronary-artery bypass graft (CABG) surgery is not known. We investigated this question in a randomized trial. We conducted a multicenter, sham-controlled trial involving adults at increased surgical risk who were undergoing on-pump CABG (with or without valve surgery) with blood cardioplegia. After anesthesia induction and before surgical incision, patients were randomly assigned to remote ischemic preconditioning (four 5-minute inflations and deflations of a standard blood-pressure cuff on the upper arm) or sham conditioning (control group). Anesthetic management and perioperative care were not standardized. The combined primary end point was death from cardiovascular causes, nonfatal myocardial infarction, coronary revascularization, or stroke, assessed 12 months after randomization. We enrolled a total of 1612 patients (811 in the control group and 801 in the ischemic-preconditioning group) at 30 cardiac surgery centers in the United Kingdom. There was no significant difference in the cumulative incidence of the primary end point at 12 months between the patients in the remote ischemic preconditioning group and those in the control group (212 patients [26.5%] and 225 patients [27.7%], respectively; hazard ratio with ischemic preconditioning, 0.95; 95% confidence interval, 0.79 to 1.15; P=0.58). Furthermore, there were no significant between-group differences in either adverse events or the secondary end points of perioperative myocardial injury (assessed on the basis of the area under the curve for the high-sensitivity assay of serum troponin T at 72 hours), inotrope score (calculated from the maximum dose of the individual inotropic agents administered in the first 3 days after surgery), acute kidney injury, duration of stay in the intensive care unit and hospital, distance on the 6-minute walk test, and quality of life. Remote ischemic preconditioning did not improve clinical outcomes in patients undergoing elective on-pump CABG with or without valve surgery. (Funded by the Efficacy and Mechanism Evaluation Program [a Medical Research Council and National Institute of Health Research partnership] and the British Heart Foundation; ERICCA ClinicalTrials.gov number, NCT01247545.).

Preconditioning electromyographic data for an upper extremity model using neural networks

NASA Technical Reports Server (NTRS)

Roberson, D. J.; Fernjallah, M.; Barr, R. E.; Gonzalez, R. V.

1994-01-01

A back propagation neural network has been employed to precondition the electromyographic signal (EMG) that drives a computational model of the human upper extremity. This model is used to determine the complex relationship between EMG and muscle activation, and generates an optimal muscle activation scheme that simulates the actual activation. While the experimental and model predicted results of the ballistic muscle movement are very similar, the activation function between the start and the finish is not. This neural network preconditions the signal in an attempt to more closely model the actual activation function over the entire course of the muscle movement.

Management of Preconditioned Calves and Impacts of Preconditioning.

PubMed

Hilton, W Mark

2015-07-01

When studying the practice of preconditioning (PC) calves, many factors need to be examined to determine if cow-calf producers should make this investment. Factors such as average daily gain, feed efficiency, available labor, length of the PC period, genetics, and marketing options must be analyzed. The health sales price advantage is an additional benefit in producing and selling PC calves but not the sole determinant of PC's financially feasibility. Studies show that a substantial advantage of PC is the selling of additional pounds at a cost of gain well below the marginal return of producing those additional pounds. Copyright © 2015 Elsevier Inc. All rights reserved.

Neuroprotective Effects of Peptides during Ischemic Preconditioning.

PubMed

Zarubina, I V; Shabanov, P D

2016-02-01

Experiments on rats showed that neurospecific protein preparations reduce the severity of neurological deficit, restore the structure of individual behavior of the animals with different hypoxia tolerance, and exert antioxidant action during chronic ischemic damage to the brain unfolding during the early and late phases of ischemic preconditioning.

40 CFR 85.2218 - Preconditioned idle test-EPA 91.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 18 2010-07-01 2010-07-01 false Preconditioned idle test-EPA 91. 85.2218 Section 85.2218 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF AIR POLLUTION FROM MOBILE SOURCES Emission Control System Performance Warranty Short...

A Three Year Comparison of Acute Respiratory Disease, Shrink and Weight Gain in Preconditioned and Non-preconditioned Illinois Beef Calves Sold at the Same Auction and Mixed in a Feedlot

PubMed Central

Woods, G. T.; Mansfield, M. E.; Webb, R. J.

1973-01-01

During 1969 to 1971, 78 preconditioned (PC) and 79 non-preconditioned (NPC) beef calves were purchased at the same auction and mixed in a feedlot. Preconditioned calves were weaned 30 days before the sale, used to drinking from a tank, and vaccinated against blackleg, malignant edema, infectious bovine rhinotracheitis (IBR), parainfluenza-3 (PI3) and bovine virus diarrhea (BVD) in 1970 and 1971, and Pasteurella hemolytica and multocida in 1971. All vaccinations were completed two to three weeks before the sale. PC calves were given thiabenzadole. PC calves had significantly less shrink after shipment and in 1971 significantly more rapid daily gain during the first weeks of the feeding period. In 1969 more PC calves were treated for acute respiratory disease than NPC calves during an outbreak of PI3 and BVD infection. In 1970 and 1971 fewer PC than NPC calves were treated for acute respiratory tract disease during outbreaks of PI3 infection. The differences in clinical respiratory disease were significant in 1971. Inclusion of two doses of P. hemolytica and P. multocida bacterin before the sale in 1971 and use of an intranasal PI3 vaccine was considered to improve the PC program. Fecal egg counts for gastrointestinal nematodes were much lower in PC calves treated with thiabenzadole than untreated NPC calves. PMID:4355470

Stress pre-conditioning with temperature, UV and gamma radiation induces tolerance against phosphine toxicity.

PubMed

Alzahrani, Saad M; Ebert, Paul R

2018-01-01

Phosphine is the only general use fumigant for the protection of stored grain, though its long-term utility is threatened by the emergence of highly phosphine-resistant pests. Given this precarious situation, it is essential to identify factors, such as stress preconditioning, that interfere with the efficacy of phosphine fumigation. We used Caenorhabditis elegans as a model organism to test the effect of pre-exposure to heat and cold shock, UV and gamma irradiation on phosphine potency. Heat shock significantly increased tolerance to phosphine by 3-fold in wild-type nematodes, a process that was dependent on the master regulator of the heat shock response, HSF-1. Heat shock did not, however, increase the resistance of a strain carrying the phosphine resistance mutation, dld-1(wr4), and cold shock did not alter the response to phosphine of either strain. Pretreatment with the LD50 of UV (18 J cm-2) did not alter phosphine tolerance in wild-type nematodes, but the LD50 (33 J cm-2) of the phosphine resistant strain (dld-1(wr4)) doubled the level of resistance. In addition, exposure to a mild dose of gamma radiation (200 Gy) elevated the phosphine tolerance by ~2-fold in both strains.

Botulinum toxin A and B raise blood flow and increase survival of critically ischemic skin flaps.

PubMed

Schweizer, Dennis F; Schweizer, Riccardo; Zhang, Shengye; Kamat, Pranitha; Contaldo, Claudio; Rieben, Robert; Eberli, Daniel; Giovanoli, Pietro; Erni, Dominique; Plock, Jan A

2013-10-01

Botulinum toxin (BTX) A and B are commonly used for aesthetic indications and in neuromuscular disorders. New concepts seek to prove efficacy of BTX for critical tissue perfusion. Our aim was to evaluate BTX A and B in a mouse model of critical flap ischemia for preoperative and intraoperative application. BTX A and B were applied on the vascular pedicle of an axial pattern flap in mice preoperatively or intraoperatively. Blood flow, tissue oxygenation, tissue metabolism, flap necrosis rate, apoptosis assay, and RhoA and eNOS expression were endpoints. Blood-flow measurements 1 d after the flap operation revealed a significant reduction to 53% in the control group, while flow was maintained or increased in all BTX groups (103%-129%). Over 5 d all BTX groups showed significant increase in blood flow to 166-187% (P < 0.01). Microdialysis revealed an increase of glucose and reduced lactate/pyruvate ratio and glycerol levels in the flap tissue of all BTX groups. This resulted in significantly improved tissue survival in all BTX groups compared with the control group (62% ± 10%; all P < 0.01): BTX A preconditioning (84% ± 5%), BTX A application intraoperatively (88% ± 4%), BTX B preconditioning (91% ± 4%), and intraoperative BTX B treatment (92% ± 5%). This was confirmed by TUNEL assay. Immunofluorescence demonstrated RhoA and eNOS expression in BTX groups. All BTX applications were similarly effective, despite pharmacologic dissimilarities and different timing. In conclusion, we were able to show on a vascular, tissue, cell, and molecular level that BTX injection to the feeding arteries supports flap survival through ameliorated blood flow and oxygen delivery. Copyright © 2013 Elsevier Inc. All rights reserved.

Exercise Preconditioning Improves Traumatic Brain Injury Outcomes

PubMed Central

Taylor, Jordan M.; Montgomery, Mitchell H.; Gregory, Eugene J.; Berman, Nancy E.J.

2015-01-01

Purpose To determine whether 6 weeks of exercise performed prior to traumatic brain injury (TBI) could improve post-TBI behavioral outcomes in mice, and if exercise increases neuroprotective molecules (vascular endothelial growth factor-A [VEGF-A], erythropoietin [EPO], and heme oxygenase-1 [HO-1]) in brain regions responsible for movement (sensorimotor cortex) and memory (hippocampus). Methods 120 mice were randomly assigned to one of four groups: 1) no exercise + no TBI (NOEX-NOTBI [n=30]), 2) no exercise + TBI (NOEX-TBI [n=30]), 3) exercise + no TBI (EX-NOTBI [n=30]), and 4) exercise + TBI (EX-TBI [n=30]). The gridwalk task and radial arm water maze were used to evaluate sensorimotor and cognitive function, respectively. Quantitative real time polymerase chain reaction and immunostaining were performed to investigate VEGF-A, EPO, and HO-1 mRNA and protein expression in the right cerebral cortex and ipsilateral hippocampus. Results EX-TBI mice displayed reduced post-TBI sensorimotor and cognitive deficits when compared to NOEX-TBI mice. EX-NOTBI and EX-TBI mice showed elevated VEGF-A and EPO mRNA in the cortex and hippocampus, and increased VEGF-A and EPO staining of sensorimotor cortex neurons 1 day post-TBI and/or post-exercise. EX-TBI mice also exhibited increased VEGF-A staining of hippocampal neurons 1 day post-TBI/post-exercise. NOEX-TBI mice demonstrated increased HO-1 mRNA in the cortex (3 days post-TBI) and hippocampus (3 and 7 days post-TBI), but HO-1 was not increased in mice that exercised. Conclusions Improved TBI outcomes following exercise preconditioning are associated with increased expression of specific neuroprotective genes and proteins (VEGF-A and EPO, but not HO-1) in the brain. PMID:26165153

Hypoxic preconditioning potentiates the trophic effects of mesenchymal stem cells on co-cultured human primary hepatocytes.

PubMed

Qin, Harry H; Filippi, Céline; Sun, Song; Lehec, Sharon; Dhawan, Anil; Hughes, Robin D

2015-12-01

Mesenchymal stem/stromal cells (MSCs) improve the metabolic function of co-cultured hepatocytes. The present study aimed to further enhance the trophic effects of co-culture with hepatocytes using hypoxic preconditioning (HPc) of the MSCs and also to investigate the underlying molecular mechanisms involved. Human adipose tissue-derived MSCs were subjected to hypoxia (2 % O2; HPc) or normoxia (20 % O2) for 24 h and then co-cultured with isolated human hepatocytes. Assays of metabolic function and apoptosis were performed to investigate the hepatotrophic and anti-apoptotic effects of co-culture. Indirect co-cultures and co-culture with MSC-conditioned medium investigated the role of paracrine factors in the hepatotrophic effects of co-culture. Reactive oxygen species (ROS) activity was antagonised with N-acetylcysteine to investigate whether HPc potentiated the effects of MSCs by intracellular ROS-dependent mechanisms. Tumour necrosis factor (TNF)-α, transforming growth factor (TGF)-β1, and extracellular collagen production was determined and CASP9 and BAX/BCL-2 signalling pathways analysed to investigate the role of soluble factors, extracellular matrix deposition, and apoptosis-associated gene signalling in the effects of co-culture. HPc potentiated the hepatotrophic and anti-apoptotic effects of co-culture by ROS-dependent mechanisms. There was increased MSC TGF-β1 production, and enhanced MSC deposition of extracellular collagen, with reduced synthesis of TNF-α, as well as a downregulation of the expression of pro-apoptotic CASP9, BAX, BID and BLK genes and upregulated expression of anti-apoptotic BCL-2 in hepatocytes. HPc potentiated the trophic and anti-apoptotic effects of MSCs on hepatocytes via mechanisms including intracellular ROS, autocrine TGF-β, extracellular collagen and caspase and BAX/BCL-2 signalling pathways.

Exercise preconditioning improves traumatic brain injury outcomes.

PubMed

Taylor, Jordan M; Montgomery, Mitchell H; Gregory, Eugene J; Berman, Nancy E J

2015-10-05

To determine whether 6 weeks of exercise performed prior to traumatic brain injury (TBI) could improve post-TBI behavioral outcomes in mice, and if exercise increases neuroprotective molecules (vascular endothelial growth factor-A [VEGF-A], erythropoietin [EPO], and heme oxygenase-1 [HO-1]) in brain regions responsible for movement (sensorimotor cortex) and memory (hippocampus). 120 mice were randomly assigned to one of four groups: (1) no exercise+no TBI (NOEX-NOTBI [n=30]), (2) no exercise+TBI (NOEX-TBI [n=30]), (3) exercise+no TBI (EX-NOTBI [n=30]), and (4) exercise+TBI (EX-TBI [n=30]). The gridwalk task and radial arm water maze were used to evaluate sensorimotor and cognitive function, respectively. Quantitative real time polymerase chain reaction and immunostaining were performed to investigate VEGF-A, EPO, and HO-1 mRNA and protein expression in the right cerebral cortex and ipsilateral hippocampus. EX-TBI mice displayed reduced post-TBI sensorimotor and cognitive deficits when compared to NOEX-TBI mice. EX-NOTBI and EX-TBI mice showed elevated VEGF-A and EPO mRNA in the cortex and hippocampus, and increased VEGF-A and EPO staining of sensorimotor cortex neurons 1 day post-TBI and/or post-exercise. EX-TBI mice also exhibited increased VEGF-A staining of hippocampal neurons 1 day post-TBI/post-exercise. NOEX-TBI mice demonstrated increased HO-1 mRNA in the cortex (3 days post-TBI) and hippocampus (3 and 7 days post-TBI), but HO-1 was not increased in mice that exercised. Improved TBI outcomes following exercise preconditioning are associated with increased expression of specific neuroprotective genes and proteins (VEGF-A and EPO, but not HO-1) in the brain. Copyright © 2015 Elsevier B.V. All rights reserved.

Protecting the human right to freedom of expression in international law.

PubMed

Howie, Emily

2018-02-01

Since its inclusion in Article 19 of the Universal Declaration of Human Rights, the right to freedom of opinion and expression has been protected in all of the relevant international human rights treaties. In international law, freedom to express opinions and ideas is considered essential at both an individual level, insofar as it contributes to the full development of a person, and being a foundation stone of democratic society. Free speech is a necessary precondition to the enjoyment of other rights, such as the right to vote, free assembly and freedom of association, and is essential to ensure press freedom. However, there is a clear and worrying global trend, including in western democracies, of governments limiting vibrant discussion and debate within civil society and among civil society, political leaders and government. Two examples illustrate this trend. First, anti-protest laws in Australia and the United States threaten the ability of people to stand together and express views on issues they care deeply about. Secondly, metadata retention laws jeopardise press freedom by undermining the confidentiality of journalists' sources and dissuading people from speaking freely on matters of public importance.

Expansion of the gateway multisite recombination cloning toolkit.

PubMed

Shearin, Harold K; Dvarishkis, Alisa R; Kozeluh, Craig D; Stowers, R Steven

2013-01-01

Precise manipulation of transgene expression in genetic model organisms has led to advances in understanding fundamental mechanisms of development, physiology, and genetic disease. Transgene construction is, however, a precondition of transgene expression, and often limits the rate of experimental progress. Here we report an expansion of the modular Gateway MultiSite recombination-cloning platform for high efficiency transgene assembly. The expansion includes two additional destination vectors and entry clones for the LexA binary transcription system, among others. These new tools enhance the expression levels possible with Gateway MultiSite generated transgenes and make possible the generation of LexA drivers and reporters with Gateway MultiSite cloning. In vivo data from transgenic Drosophila functionally validating each novel component are presented and include neuronal LexA drivers, LexAop2 red and green fluorescent synaptic vesicle reporters, TDC2 and TRH LexA, GAL4, and QF drivers, and LexAop2, UAS, and QUAS channelrhodopsin2 T159C reporters.

Expansion of the Gateway MultiSite Recombination Cloning Toolkit

PubMed Central

Shearin, Harold K.; Dvarishkis, Alisa R.; Kozeluh, Craig D.; Stowers, R. Steven

2013-01-01

Precise manipulation of transgene expression in genetic model organisms has led to advances in understanding fundamental mechanisms of development, physiology, and genetic disease. Transgene construction is, however, a precondition of transgene expression, and often limits the rate of experimental progress. Here we report an expansion of the modular Gateway MultiSite recombination-cloning platform for high efficiency transgene assembly. The expansion includes two additional destination vectors and entry clones for the LexA binary transcription system, among others. These new tools enhance the expression levels possible with Gateway MultiSite generated transgenes and make possible the generation of LexA drivers and reporters with Gateway MultiSite cloning. In vivo data from transgenic Drosophila functionally validating each novel component are presented and include neuronal LexA drivers, LexAop2 red and green fluorescent synaptic vesicle reporters, TDC2 and TRH LexA, GAL4, and QF drivers, and LexAop2, UAS, and QUAS channelrhodopsin2 T159C reporters. PMID:24204935

40 CFR 86.132-96 - Vehicle preconditioning.

Code of Federal Regulations, 2013 CFR

2013-07-01

... outdoors awaiting testing, to prevent unusual loading of the canisters. During this time care must be taken... idle again for 1 minute. (H) After the vehicle is turned off the last time, it may be tested for... preconditioned according to the following procedure. For vehicles with multiple canisters in a series...

Revealing Preconditions for Trustful Collaboration in CSCL

ERIC Educational Resources Information Center

Gerdes, Anne

2010-01-01

This paper analyses preconditions for trust in virtual learning environments. The concept of trust is discussed with reference to cases reporting trust in cyberspace and through a philosophical clarification holding that trust in the form of self-surrender is a common characteristic of all human co-existence. In virtual learning environments,…

Comparison results on preconditioned SOR-type iterative method for Z-matrices linear systems

NASA Astrophysics Data System (ADS)

Wang, Xue-Zhong; Huang, Ting-Zhu; Fu, Ying-Ding

2007-09-01

In this paper, we present some comparison theorems on preconditioned iterative method for solving Z-matrices linear systems, Comparison results show that the rate of convergence of the Gauss-Seidel-type method is faster than the rate of convergence of the SOR-type iterative method.

33 CFR 183.220 - Preconditioning for tests.

Code of Federal Regulations, 2011 CFR

2011-07-01

... (CONTINUED) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Flotation Requirements for Outboard Boats Rated for Engines of More Than 2 Horsepower General § 183.220 Preconditioning for tests. A boat must meet the... boat. (b) The boat must be loaded with a quantity of weight that, when submerged, is equal to the sum...

Brief pressure overload of the left ventricle reduces myocardial infarct size via activation of protein kinase C.

PubMed

Tang, Chia-Yu; Lai, Chang-Chi; Chiang, Shu-Chiung; Tseng, Kuo-Wei; Huang, Cheng-Hsiung

2015-09-01

We have previously reported that brief pressure overload of the left ventricle reduced myocardial infarct (MI) size. However, the role of protein kinase C (PKC) remains uncertain. In this study, we investigated whether pressure overload reduces MI size by activating PKC. MI was induced by a 40-minute occlusion of the left anterior descending coronary artery and a 3-hour reperfusion in anesthetized Sprague-Dawley rats. MI size was determined using triphenyl tetrazolium chloride staining. Brief pressure overload was achieved by two 10-minute partial snarings of the ascending aorta, raising the systolic left ventricular pressure 50% above the baseline value. Ischemic preconditioning was elicited by two 10-minute coronary artery occlusions and 10-minute reperfusions. Dimethyl sulfoxide (vehicle) or calphostin C (0.1 mg/kg, a specific inhibitor of PKC) was administered intravenously as pretreatment. The MI size, expressed as the percentage of the area at risk, was significantly reduced in the pressure overload group and the ischemic preconditioning group (19.0 ± 2.9% and 18.7 ± 3.0% vs. 26.1 ± 2.6% in the control group, where p < 0.001). Pretreatment with calphostin C significantly limited the protection by pressure overload and ischemic preconditioning (25.2 ± 2.4% and 25.0 ± 2.3%, where p < 0.001). Calphostin C itself did not significantly affect MI size (25.5 ± 2.4%). Additionally, the hemodynamics, area at risk, and mortality were not significantly different. Brief pressure overload of the left ventricle reduced MI size. Since calphostin C significantly limited the decrease of MI size, our results suggested that brief pressure overload reduces MI size via activation of PKC. Copyright © 2015. Published by Elsevier Taiwan.

Mechanism of sphingosine-1-phosphate induced cardioprotection against I/R injury in diabetic rat heart: Possible involvement of glycogen synthase kinase 3β and mitochondrial permeability transition pore.

PubMed

Rana, Ajay; Sharma, Saurabh

2016-02-01

There is growing evidence that diabetes mellitus causes attenuation of the bioactive metabolite of membrane sphingolipids, sphingosine-1-phosphate, and this may be a key mechanism in the decreased cardioprotective effect of ischaemic preconditioning (IPC) in the diabetic heart. Thus, this study has been designed to investigate the role and pharmacological potential of sphingosine-1-phosphate in diabetic rat heart. Diabetes was produced in Wistar rats by administration of a low dose of streptozotocin (STZ) (35 mg/kg, i.p., once) and feeding a high fat diet (HFD) for 6 weeks. Isolated rat heart was subjected to 30 min ischaemia followed by 120 min of reperfusion (I/R). The heart was subjected to pre-ischaemic treatment (before ischaemia for 20 min) and pharmacological preconditioning with the S1P agonist FTY720 (0.6 μmol/L) with and without atractyloside (an mPTP opener; in the last episode of reperfusion before I/R). Myocardial infarction was assessed in terms of increase in lactate dehydrogenase (LDH), creatinine kinase-MB (CK-MB), myeloperoxidase (MPO) level and infarct size (triphenyltetrazolium chloride staining). Immunohistochemistry analysis was done for assessment of tumour necrosis factor (TNF)-α and glycogen synthase kinase (GSK)-3β level in cardiac tissue. Pre-ischaemic treatment and pharmacological preconditioning with FTY720 significantly decreased I/R-induced myocardial infarction, TNF-alpha, GSK-3β level and release of LDH and CK-MB as compared to control group. The cardioprotective effect of S1P agonist was significantly attenuated by atractyloside. It may be concluded that S1P agonist FTY720 prevents the diabetic heart from ischaemic reperfusion injury, possibly through inhibition of GSK-3β and regulation of opening of mitochondrial permeability transition pore. © 2016 John Wiley & Sons Australia, Ltd.

The paradigm of postconditioning to protect the heart

PubMed Central

Penna, C; Mancardi, D; Raimondo, S; Geuna, S; Pagliaro, P

2008-01-01

Abstract Ischaemic preconditioning limits the damage induced by subsequent ischaemia/reperfusion (I/R). However, preconditioning is of little practical use as the onset of an infarction is usually unpredictable. Recently, it has been shown that the heart can be protected against the extension of I/R injury if brief (10–30 sec.) coronary occlusions are performed just at the beginning of the reperfusion. This procedure has been called postconditioning (PostC). It can also be elicited at a distant organ, termed remote PostC, by intermittent pacing (dyssynchrony-induced PostC) and by pharmacological interventions, that is pharmacological PostC. In particular, brief applications of intermittent bradykinin or diazoxide at the beginning of reperfusion reproduce PostC protection. PostC reduces the reperfusion-induced injury, blunts oxidant-mediated damages and attenuates the local inflammatory response to reperfusion. PostC induces a reduction of infarct size, apoptosis, endothelial dysfunction and activation, neutrophil adherence and arrhythmias. Whether it reduces stunning is not clear yet. Similar to preconditioning, PostC triggers signalling pathways and activates effectors implicated in other cardioprotective manoeuvres. Adenosine and bradykinin are involved in PostC triggering. PostC triggers survival kinases (RISK), including A t and extracellular signal-regulated kinase (ERK). Nitric oxide, via nitric oxide synthase and non-enzymatic production, cyclic guanosine monophosphate (cGMP) and protein kinases G (PKG) participate in PostC. PostC-induced protection also involves an early redox-sensitive mechanism, and mitochondrial adenosine-5′ -triphosphate (ATP)-sensitive K+ and PKC activation. Protective pathways activated by PostC appear to converge on mitochondrial permeability transition pores, which are inhibited by acidosis and glycogen synthase kinase-3β (GSK-3β). In conclusion, the first minutes of reperfusion represent a window of opportunity for triggering the aforementioned mediators which will in concert lead to protection against reperfusion injury. Pharmacological PostC and possibly remote PostC may have a promising future in clinical scenario. PMID:18182064

Transplantation of hypoxia preconditioned bone marrow mesenchymal stem cells enhances angiogenesis and osteogenesis in rabbit femoral head osteonecrosis.

PubMed

Fan, Lihong; Zhang, Chen; Yu, Zefeng; Shi, Zhibin; Dang, Xiaoqian; Wang, Kunzheng

2015-12-01

Osteonecrosis of the femoral head may be a disease resulting from abnormal proliferation or differentiation of mesenchymal stem cells. The present investigation explored the novel strategy of hypoxia-preconditioned BMMSCs to reverse the impairment of osteonecrosis BMMSCs and enhance the therapeutic potential of hypoxia-treated BMMSC transplantation. BMMSCs from the anterior superior iliac spine region of osteonecrosis rabbit were cultured under 20% O2 or 2% O2 conditions. Normal BMMSCs were cultured under 20% O2 condition as control. Growth factors secreted were examined by enzyme-linked immunosorbent assay. 20% O2 or 2% O2 BMMSCs were injected into the femoral head of rabbits after core decompression. Cell viability and apoptosis were assessed in vitro, and TUNEL staining of the femoral head was analyzed after transplantation. Angiogenesis (capillary-like structure formation, CD31 immunohistochemical staining and ink infusion angiography) and osteogenesis (Alizarin red-S staining, micro-CT scanning and OCN immunohistochemical staining) tests were conducted as well. 2% O2 exposure up-regulated growth factor secretion in BMMSCs. Apoptosis in 2% O2 group was lower when compared with that in 20% O2 osteonecrosis group. Cell viability in 2% O2 was significantly higher when compared with that in 20% O2 osteonecrosis group. Growth factor secretion, cell viability, apoptosis, capillary-like structure formation, Alizarin red-S staining, and ALP staining showed no difference between the 2% O2 BMMSC and normal BMMSC groups. Transplantation of 2% O2 versus 20% O2 mesenchymal stem cells after core decompression resulted in an increase in angiogenesis function and a decrease in local tissue apoptosis. Our study also found that osteogenesis function was improved after hypoxic stem cell transplantation. Hypoxic preconditioning of BMMSCs is an effective means of reversing the impairment of osteonecrosis BMMSCs, promoting their regenerative capability and therapeutic potential for the treatment of osteonecrosis. Copyright © 2015 Elsevier Inc. All rights reserved.

PBMC: Pre-conditioned Backward Monte Carlo code for radiative transport in planetary atmospheres

NASA Astrophysics Data System (ADS)

García Muñoz, A.; Mills, F. P.

2017-08-01

PBMC (Pre-Conditioned Backward Monte Carlo) solves the vector Radiative Transport Equation (vRTE) and can be applied to planetary atmospheres irradiated from above. The code builds the solution by simulating the photon trajectories from the detector towards the radiation source, i.e. in the reverse order of the actual photon displacements. In accounting for the polarization in the sampling of photon propagation directions and pre-conditioning the scattering matrix with information from the scattering matrices of prior (in the BMC integration order) photon collisions, PBMC avoids the unstable and biased solutions of classical BMC algorithms for conservative, optically-thick, strongly-polarizing media such as Rayleigh atmospheres.

Preserving Symmetry in Preconditioned Krylov Subspace Methods

NASA Technical Reports Server (NTRS)

Chan, Tony F.; Chow, E.; Saad, Y.; Yeung, M. C.

1996-01-01

We consider the problem of solving a linear system Ax = b when A is nearly symmetric and when the system is preconditioned by a symmetric positive definite matrix M. In the symmetric case, one can recover symmetry by using M-inner products in the conjugate gradient (CG) algorithm. This idea can also be used in the nonsymmetric case, and near symmetry can be preserved similarly. Like CG, the new algorithms are mathematically equivalent to split preconditioning, but do not require M to be factored. Better robustness in a specific sense can also be observed. When combined with truncated versions of iterative methods, tests show that this is more effective than the common practice of forfeiting near-symmetry altogether.

Fractal-like kinetics, a possible link between preconditioning and sepsis immunodepression. On the chemical basis of innate immunity.

PubMed

Vasilescu, C; Olteanu, M; Flondor, P

2012-01-01

In a recent paper the authors hypothesized that the so called fractal-like enzyme kinetics of intracellular reactions may explain the preconditioning effect in biology (Vasilescu C, Olteanu M, Flondor P, Revue Roumaine de Chimie. 2011; 56(7): 751-7). Inside cells the reaction kinetics is very well described by fractal-like kinetics. In the present work some clinical implications of this model are analyzed. Endotoxin tolerance is a particular case of preconditioning and shows similarities with the immunodepression seen in some sepsis patients. This idea offers a theoretical support for modulation of the enzymatic activity of the cell by changing the fractal dimension of the cytoskeleton.

TARGETED DELETION OF INDUCIBLE HEAT SHOCK PROTEIN 70 ABROGATES THE LATE INFARCT-SPARING EFFECT OF MYOCARDIAL ISCHEMIC PRECONDITIONING

EPA Science Inventory

Abstract submitted for 82nd annual meeting of the American Association for Thoracic Surgery, May 4-8, 2002 in Washington D.C.

Targeted Deletion of Inducible Heat Shock Protein 70 Abrogates the Late Infarct-Sparing Effect of Myocardial Ischemic Preconditioning

Craig...

40 CFR 86.532-78 - Vehicle preconditioning.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 1978 and Later New Motorcycles; Test Procedures § 86.532-78 Vehicle preconditioning. (a) The vehicle shall be moved to the test area and the following operations performed: (1) The fuel tank(s) shall be drained through the provided fuel tank(s) drain(s) and charged with the specified test fuel, § 86.513, to...

40 CFR 86.532-78 - Vehicle preconditioning.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 1978 and Later New Motorcycles; Test Procedures § 86.532-78 Vehicle preconditioning. (a) The vehicle shall be moved to the test area and the following operations performed: (1) The fuel tank(s) shall be drained through the provided fuel tank(s) drain(s) and charged with the specified test fuel, § 86.513, to...

40 CFR 86.532-78 - Vehicle preconditioning.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 1978 and Later New Motorcycles; Test Procedures § 86.532-78 Vehicle preconditioning. (a) The vehicle shall be moved to the test area and the following operations performed: (1) The fuel tank(s) shall be drained through the provided fuel tank(s) drain(s) and charged with the specified test fuel, § 86.513, to...

40 CFR 86.532-78 - Vehicle preconditioning.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 1978 and Later New Motorcycles; Test Procedures § 86.532-78 Vehicle preconditioning. (a) The vehicle shall be moved to the test area and the following operations performed: (1) The fuel tank(s) shall be drained through the provided fuel tank(s) drain(s) and charged with the specified test fuel, § 86.513, to...

40 CFR 86.532-78 - Vehicle preconditioning.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 1978 and Later New Motorcycles; Test Procedures § 86.532-78 Vehicle preconditioning. (a) The vehicle shall be moved to the test area and the following operations performed: (1) The fuel tank(s) shall be drained through the provided fuel tank(s) drain(s) and charged with the specified test fuel, § 86.513, to...

The survey of preconditioners used for accelerating the rate of convergence in the Gauss-Seidel method

NASA Astrophysics Data System (ADS)

Niki, Hiroshi; Harada, Kyouji; Morimoto, Munenori; Sakakihara, Michio

2004-03-01

Several preconditioned iterative methods reported in the literature have been used for improving the convergence rate of the Gauss-Seidel method. In this article, on the basis of nonnegative matrix, comparisons between some splittings for such preconditioned matrices are derived. Simple numerical examples are also given.

Attributes and Preconditions of Collaboration between and among Schools, Institutions of Higher Education, and State Education Agencies. Instructional Leadership and School Improvement.

ERIC Educational Resources Information Center

Reed, Patricia; Cejda, Brent

Recognizing that successful collaboration among schools, institutes of higher education, and state education agencies to is an important factor in the professional development of education personnel, this document examines existing knowledge of interorganizational collaboration and identifies organizational preconditions conducive to the…

Xenon Preconditioning Protects against Renal Ischemic-Reperfusion Injury via HIF-1α Activation

PubMed Central

Ma, Daqing; Lim, Ta; Xu, Jing; Tang, Haidy; Wan, Yanjie; Zhao, Hailin; Hossain, Mahmuda; Maxwell, Patrick H.; Maze, Mervyn

2009-01-01

The mortality rate from acute kidney injury after major cardiovascular operations can be as high as 60%, and no therapies have been proved to prevent acute kidney injury in this setting. Here, we show that preconditioning with the anesthetic gas xenon activates hypoxia-inducible factor 1α (HIF-1α) and its downstream effectors erythropoietin and vascular endothelial growth factor in a time-dependent manner in the kidneys of adult mice. Xenon increased the efficiency of HIF-1α translation via modulation of the mammalian target of rapamycin pathway. In a model of renal ischemia-reperfusion injury, xenon provided morphologic and functional renoprotection; hydrodynamic injection of HIF-1α small interfering RNA demonstrated that this protection is HIF-1α dependent. These results suggest that xenon preconditioning is a natural inducer of HIF-1α and that administration of xenon before renal ischemia can prevent acute renal failure. If these data are confirmed in the clinical setting, then preconditioning with xenon may be beneficial before procedures that temporarily interrupt renal perfusion. PMID:19144758

Pharmacological preconditioning by milrinone: memory preserving and neuroprotective effect in ischemia-reperfusion injury in mice.

PubMed

Saklani, Reetu; Jaggi, Amteshwar; Singh, Nirmal

2010-07-01

We tested the neuroprotective effect of milrinone, a phosphodiesterase III inhibitor, in pharmacological preconditioning. Bilateral carotid artery occlusion for 12 min followed by reperfusion for 24 h produced ischemia-reperfusion (I/R) cerebral injury in male Swiss albino mice. Cerebral infarct size was measured using triphenyltetrazolium chloride staining. Memory was assessed using the Morris water maze test, and motor coordination was evaluated using the inclined beam walking test, rota-rod test, and lateral push test. Milrinone (50 microg/kg & 100 microg/kg i.v.) was administered 24 h before surgery in a separate group of animals to induce pharmacological preconditioning. I/R increased cerebral infarct size and impaired memory and motor coordination. Milrinone treatment significantly decreased cerebral infarct size and reversed I/R-induced impairments in memory and motor coordination. This neuroprotective effect was blocked by ruthenium red (3 mg/kg, s.c.), an intracellular ryanodine receptor blocker. These findings indicate that milrinone preconditioning exerts a marked neuroprotective effect on the ischemic brain, putatively due to increased intracellular calcium levels activating calcium-sensitive signal transduction cascades.

Remote ischaemic preconditioning and prevention of cerebral injury.

PubMed

Rehni, Ashish K; Shri, Richa; Singh, Manjeet

2007-03-01

Bilateral carotid artery occlusion of 10 min followed by reperfusion for 24 hr was employed in present study to produce ischaemia and reperfusion induced cerebral injury in mice. Cerebral infarct size was measured using triphenyltetrazolium chloride staining. Short-term memory was evaluated using elevated plus maze. Inclined beam walking test was employed to assess motor incoordination. Bilateral carotid artery occlusion followed by reperfusion produced cerebral infarction and impaired short-term memory, motor co-ordination and lateral push response. A preceding episode of mesenteric artery occlusion for 15 min and reperfusion of 15 min (remote mesenteric ischaemic preconditioning) prevented markedly ischaemia-reperfusion-induced cerebral injury measured in terms of infarct size, loss of short-term memory, motor coordination and lateral push response. Glibenclamide (5 mg/kg, iv) a KATP channel blocker and caffeine (7 mg/kg, iv) an adenosine receptor blocker attenuated the neuroprotective effect of remote mesenteric ischaemic preconditioning. It may be concluded that neuroprotective effect of remote mesenteric ischaemic preconditioning may be due to activation of adenosine receptors and consequent activation of KATP channels in mice.

Preconditioning for traumatic brain injury

PubMed Central

Yokobori, Shoji; Mazzeo, Anna T; Hosein, Khadil; Gajavelli, Shyam; Dietrich, W. Dalton; Bullock, M. Ross

2016-01-01

Traumatic brain injury (TBI) treatment is now focused on the prevention of primary injury and reduction of secondary injury. However, no single effective treatment is available as yet for the mitigation of traumatic brain damage in humans. Both chemical and environmental stresses applied before injury, have been shown to induce consequent protection against post-TBI neuronal death. This concept termed “preconditioning” is achieved by exposure to different pre-injury stressors, to achieve the induction of “tolerance” to the effect of the TBI. However, the precise mechanisms underlying this “tolerance” phenomenon are not fully understood in TBI, and therefore even less information is available about possible indications in clinical TBI patients. In this review we will summarize TBI pathophysiology, and discuss existing animal studies demonstrating the efficacy of preconditioning in diffuse and focal type of TBI. We will also review other non-TBI preconditionng studies, including ischemic, environmental, and chemical preconditioning, which maybe relevant to TBI. To date, no clinical studies exist in this field, and we speculate on possible futureclinical situation, in which pre-TBI preconditioning could be considered. PMID:24323189

Myocardial protection using diadenosine tetraphosphate with pharmacological preconditioning.

PubMed

Ahmet, I; Sawa, Y; Nishimura, M; Yamaguchi, T; Kitakaze, M; Matsuda, H

2000-09-01

We have reported a similar cardioprotective effect and mechanism of diadenosine tetraphosphate (AP4A) and ischemic preconditioning in rat hearts. In this study, the applicability of AP4A administration to cardiac surgery was tested by using a canine cardiopulmonary bypass model. Hearts underwent 60 minutes of cardioplegic arrest (34 degrees C) by a single dose of cardioplegia. Cardioplegia contained either AP4A (40 micromol/L; n = 6) or saline (n = 6). Beagles were weaned from cardiopulmonary bypass 30 minutes after reperfusion, and left ventricular function was evaluated after another 30 minutes by using the cardiac loop analysis system. Administration of AP4A significantly improved the postischemic recovery of cardiac function and reduced the leakage of serum creatine kinase compared with saline. Systemic vascular resistance, mean aortic blood pressure, and the electrocardiographic indices were not significantly altered by AP4A administration. Administration of AP4A was cardioprotective without apparent adverse effects. Because the cardioprotective mechanism may be similar to that of ischemic preconditioning, the addition of AP4A into cardioplegia may be a novel safe method for clinical application of preconditioning cardioprotection.

Preconditioned Alternating Projection Algorithms for Maximum a Posteriori ECT Reconstruction

PubMed Central

Krol, Andrzej; Li, Si; Shen, Lixin; Xu, Yuesheng

2012-01-01

We propose a preconditioned alternating projection algorithm (PAPA) for solving the maximum a posteriori (MAP) emission computed tomography (ECT) reconstruction problem. Specifically, we formulate the reconstruction problem as a constrained convex optimization problem with the total variation (TV) regularization. We then characterize the solution of the constrained convex optimization problem and show that it satisfies a system of fixed-point equations defined in terms of two proximity operators raised from the convex functions that define the TV-norm and the constrain involved in the problem. The characterization (of the solution) via the proximity operators that define two projection operators naturally leads to an alternating projection algorithm for finding the solution. For efficient numerical computation, we introduce to the alternating projection algorithm a preconditioning matrix (the EM-preconditioner) for the dense system matrix involved in the optimization problem. We prove theoretically convergence of the preconditioned alternating projection algorithm. In numerical experiments, performance of our algorithms, with an appropriately selected preconditioning matrix, is compared with performance of the conventional MAP expectation-maximization (MAP-EM) algorithm with TV regularizer (EM-TV) and that of the recently developed nested EM-TV algorithm for ECT reconstruction. Based on the numerical experiments performed in this work, we observe that the alternating projection algorithm with the EM-preconditioner outperforms significantly the EM-TV in all aspects including the convergence speed, the noise in the reconstructed images and the image quality. It also outperforms the nested EM-TV in the convergence speed while providing comparable image quality. PMID:23271835

Amelioration of rCBF and PbtO2 following TBI at high altitude by hyperbaric oxygen pre-conditioning.

PubMed

Hu, Shengli; Li, Fei; Luo, Haishui; Xia, Yongzhi; Zhang, Jiuquan; Hu, Rong; Cui, Gaoyu; Meng, Hui; Feng, Hua

2010-03-01

Hypobaric hypoxia at high altitude can lead to brain damage and pre-conditioning with hyperbaric oxygen (HBO) can reduce ischemic/hypoxic brain injury. This study investigates the effects of high altitude on traumatic brain injury (TBI) and examines the neuroprotection provided by HBO preconditioning against TBI. Rats were randomly divided into four groups: HBO pre-conditioning group (HBOP, n=10), high altitude group (HA, n=10), plain control group (PC, n=10) and plain sham operation group (sham, n=10). All groups were subjected to head trauma by weight drop device except for the sham group. Rats from each group were examined for neurological function, regional cerebral blood flow (rCBF) and brain tissue oxygen pressure (PbtO(2)) and were killed for analysis by transmission electron microscope. The score of neurological deficits in the HA group was highest, followed by the HBOP group and the PC group, respectively. Both rCBF and PbtO(2) were the lowest in the HA group. Brain morphology and structure seen via the transmission electron microscope was diminished in the HA group, while fewer pathological injuries occurred in the HBOP and PC groups. High altitude aggravates TBI significantly and HBO pre-conditioning can attenuate TBI in rats at high altitude by improvement of rCBF and PbtO(2). Pre-treatment with HBO might be beneficial for people traveling to high altitude locations.

Hypoxic-Preconditioned Bone Marrow Stem Cell Medium Significantly Improves Outcome After Retinal Ischemia in Rats

PubMed Central

Roth, Steven; Dreixler, John C.; Mathew, Biji; Balyasnikova, Irina; Mann, Jacob R.; Boddapati, Venkat; Xue, Lai; Lesniak, Maciej S.

2016-01-01

Purpose We have previously demonstrated the protective effect of bone marrow stem cell (BMSC)-conditioned medium in retinal ischemic injury. We hypothesized here that hypoxic preconditioning of stem cells significantly enhances the neuroprotective effect of the conditioned medium and thereby augments the protective effect in ischemic retina. Methods Rats were subjected to retinal ischemia by increasing intraocular pressure to 130 to 135 mm Hg for 55 minutes. Hypoxic-preconditioned, hypoxic unconditioned, or normoxic medium was injected into the vitreous 24 hours after ischemia ended. Recovery was assessed 7 days after injections by comparing electroretinography measurements, histologic examination, and apoptosis (TUNEL, terminal deoxynucleotidyl transferase–mediated dUTP nick end labeling assay). To compare proteins secreted into the medium in the groups and the effect of hypoxic exposure, we used rat cytokine arrays. Results Eyes injected with hypoxic BMSC–conditioned medium 24 hours after ischemia demonstrated significantly enhanced return of retinal function, decreased retinal ganglion cell layer loss, and attenuated apoptosis compared to those administered normoxic or hypoxic unconditioned medium. Hypoxic-preconditioned medium had 21 significantly increased protein levels compared to normoxic medium. Conclusions The medium from hypoxic-preconditioned BMSCs robustly restored retinal function and prevented cell loss after ischemia when injected 24 hours after ischemia. The protective effect was even more pronounced than in our previous studies of normoxic conditioned medium. Prosurvival signals triggered by the secretome may play a role in this neuroprotective effect. PMID:27367588

Solving large test-day models by iteration on data and preconditioned conjugate gradient.

PubMed

Lidauer, M; Strandén, I; Mäntysaari, E A; Pösö, J; Kettunen, A

1999-12-01

A preconditioned conjugate gradient method was implemented into an iteration on a program for data estimation of breeding values, and its convergence characteristics were studied. An algorithm was used as a reference in which one fixed effect was solved by Gauss-Seidel method, and other effects were solved by a second-order Jacobi method. Implementation of the preconditioned conjugate gradient required storing four vectors (size equal to number of unknowns in the mixed model equations) in random access memory and reading the data at each round of iteration. The preconditioner comprised diagonal blocks of the coefficient matrix. Comparison of algorithms was based on solutions of mixed model equations obtained by a single-trait animal model and a single-trait, random regression test-day model. Data sets for both models used milk yield records of primiparous Finnish dairy cows. Animal model data comprised 665,629 lactation milk yields and random regression test-day model data of 6,732,765 test-day milk yields. Both models included pedigree information of 1,099,622 animals. The animal model ¿random regression test-day model¿ required 122 ¿305¿ rounds of iteration to converge with the reference algorithm, but only 88 ¿149¿ were required with the preconditioned conjugate gradient. To solve the random regression test-day model with the preconditioned conjugate gradient required 237 megabytes of random access memory and took 14% of the computation time needed by the reference algorithm.

Active Focal Zone Sharpening for High-Precision Treatment Using Histotripsy

PubMed Central

Wang, Tzu-Yin; Xu, Zhen; Hall, Timothy L.; Fowlkes, J. Brian; Roberts, William W.; Cain, Charles A.

2011-01-01

The goal of this study is to develop a focal zone sharpening strategy that produces more precise lesions for pulsed cavitational ultrasound therapy, or histotripsy. Precise and well-confined lesions were produced by locally suppressing cavitation in the periphery of the treatment focus without affecting cavitation in the center. The local suppression of cavitation was achieved using cavitation nuclei preconditioning pulses to actively control cavitation in the periphery of the focus. A 1-MHz 513-element therapeutic array was used to generate both the therapy and the nuclei preconditioning pulses. For therapy, 10-cycle bursts at 100-Hz pulse repetition frequency with P−/P+ pressure of 21/76 MPa were delivered to the geometric focus of the therapeutic array. For nuclei preconditioning, a different pulse was delivered to an annular region immediately surrounding the focus before each therapy pulse. A parametric study on the effective pressure, pulse duration, and delivery time of the preconditioning pulse was conducted in red blood cell-gel phantoms, where cavitational damage was indicated by the color change resulting from local cell lysis. Results showed that a short-duration (20 µs) preconditioning pulse at a medium pressure (P−/P+ pressure of 7.2/13.6 MPa) delivered shortly before (30 µs) the therapy pulse substantially suppressed the peripheral damage by 77 ± 13% while complete fractionation in the focal center was maintained. High-speed imaging of the bubble cloud showed a substantial decrease in the maximum width of the bubble cloud by 48 ± 24% using focal zone sharpening. Experiments in ex vivo livers confirmed that highly confined lesions were produced in real tissues as well as in the phantoms. This study demonstrated the feasibility of active focal zone sharpening using cavitation nuclei preconditioning, allowing for increased treatment precision compared with the natural focal width of the therapy transducer. PMID:21342816

Active focal zone sharpening for high-precision treatment using histotripsy.

PubMed

Wang, Tzu-Yin; Xu, Zhen; Hall, Timothy; Fowlkes, J; Roberts, William; Cain, Charles

2011-02-01

The goal of this study is to develop a focal zone sharpening strategy that produces more precise lesions for pulsed cavitational ultrasound therapy, or histotripsy. Precise and well-confined lesions were produced by locally suppressing cavitation in the periphery of the treatment focus without affecting cavitation in the center. The local suppression of cavitation was achieved using cavitation nuclei preconditioning pulses to actively control cavitation in the periphery of the focus. A 1-MHz 513-element therapeutic array was used to generate both the therapy and the nuclei preconditioning pulses. For therapy, 10-cycle bursts at 100-Hz pulse repetition frequency with P-/P+ pressure of 21/76 MPa were delivered to the geometric focus of the therapeutic array. For nuclei preconditioning, a different pulse was delivered to an annular region immediately surrounding the focus before each therapy pulse. A parametric study on the effective pressure, pulse duration, and delivery time of the preconditioning pulse was conducted in red blood cell-gel phantoms, where cavitational damage was indicated by the color change resulting from local cell lysis. Results showed that a short-duration (20 μs) preconditioning pulse at a medium pressure (P-/P+ pressure of 7.2/13.6 MPa) delivered shortly before (30 μs) the therapy pulse substantially suppressed the peripheral damage by 77 ± 13% while complete fractionation in the focal center was maintained. High-speed imaging of the bubble cloud showed a substantial decrease in the maximum width of the bubble cloud by 48 ± 24% using focal zone sharpening. Experiments in ex vivo livers confirmed that highly confined lesions were produced in real tissues as well as in the phantoms. This study demonstrated the feasibility of active focal zone sharpening using cavitation nuclei preconditioning, allowing for increased treatment precision compared with the natural focal width of the therapy transducer.

The GRONORUN 2 study: effectiveness of a preconditioning program on preventing running related injuries in novice runners. The design of a randomized controlled trial.

PubMed

Bredeweg, Steef W; Zijlstra, Sjouke; Buist, Ida

2010-09-01

Distance running is a popular recreational exercise. It is a beneficial activity for health and well being. However, running may also cause injuries, especially of the lower extremities. In literature there is no agreement what intrinsic and extrinsic factors cause running related injuries (RRIs). In theory, most RRIs are elicited by training errors, this too much, too soon. In a preconditioning program runners can adapt more gradually to the high mechanical loads of running and will be less susceptible to RRIs. In this study the effectiveness of a 4-week preconditioning program on the incidence of RRIs in novice runners prior to a training program will be studied. The GRONORUN 2 (Groningen Novice Running) study is a two arm randomized controlled trial studying the effect of a 4-week preconditioning (PRECON) program in a group of novice runners. All participants wanted to train for the recreational Groningen 4-Mile running event. The PRECON group started a 4-week preconditioning program with walking and hopping exercises 4 weeks before the start of the training program. The control (CON) and PRECON group started a frequently used 9-week training program in preparation for the Groningen 4-Mile running event.During the follow up period participants registered their running exposure, other sporting activities and running related injuries in an Internet based running log. The primary outcome measure was the number of RRIs. RRI was defined as a musculoskeletal ailment or complaint of the lower extremities or back causing a restriction on running for at least three training sessions. The GRONORUN 2 study will add important information to the existing running science. The concept of preconditioning is easy to implement in existing training programs and will hopefully prevent RRIs especially in novice runners. The Netherlands National Trial Register NTR1906. The NTR is part of the WHO Primary Registries.

An M-step preconditioned conjugate gradient method for parallel computation

NASA Technical Reports Server (NTRS)

Adams, L.

1983-01-01

This paper describes a preconditioned conjugate gradient method that can be effectively implemented on both vector machines and parallel arrays to solve sparse symmetric and positive definite systems of linear equations. The implementation on the CYBER 203/205 and on the Finite Element Machine is discussed and results obtained using the method on these machines are given.

40 CFR 1065.590 - PM sampling media (e.g., filters) preconditioning and tare weighing.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 32 2010-07-01 2010-07-01 false PM sampling media (e.g., filters... Specified Duty Cycles § 1065.590 PM sampling media (e.g., filters) preconditioning and tare weighing. Before an emission test, take the following steps to prepare PM sampling media (e.g., filters) and equipment...

40 CFR 1065.590 - PM sampling media (e.g., filters) preconditioning and tare weighing.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 34 2012-07-01 2012-07-01 false PM sampling media (e.g., filters... Specified Duty Cycles § 1065.590 PM sampling media (e.g., filters) preconditioning and tare weighing. Before an emission test, take the following steps to prepare PM sampling media (e.g., filters) and equipment...

40 CFR 1065.590 - PM sampling media (e.g., filters) preconditioning and tare weighing.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 34 2013-07-01 2013-07-01 false PM sampling media (e.g., filters... Specified Duty Cycles § 1065.590 PM sampling media (e.g., filters) preconditioning and tare weighing. Before an emission test, take the following steps to prepare PM sampling media (e.g., filters) and equipment...

40 CFR 1065.590 - PM sampling media (e.g., filters) preconditioning and tare weighing.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 33 2011-07-01 2011-07-01 false PM sampling media (e.g., filters... Specified Duty Cycles § 1065.590 PM sampling media (e.g., filters) preconditioning and tare weighing. Before an emission test, take the following steps to prepare PM sampling media (e.g., filters) and equipment...

40 CFR 1065.590 - PM sampling media (e.g., filters) preconditioning and tare weighing.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 33 2014-07-01 2014-07-01 false PM sampling media (e.g., filters... Specified Duty Cycles § 1065.590 PM sampling media (e.g., filters) preconditioning and tare weighing. Before an emission test, take the following steps to prepare PM sampling media (e.g., filters) and equipment...

Cognitive Preconditions of Early Reading and Spelling: A Latent-Variable Approach with Longitudinal Data

ERIC Educational Resources Information Center

Preßler, Anna-Lena; Könen, Tanja; Hasselhorn, Marcus; Krajewski, Kristin

2014-01-01

The aim of the present study was to empirically disentangle the interdependencies of the impact of nonverbal intelligence, working memory capacities, and phonological processing skills on early reading decoding and spelling within a latent variable approach. In a sample of 127 children, these cognitive preconditions were assessed before the onset…

Measuring Five Preconditions of Success for African American Male Students in Community Colleges

ERIC Educational Resources Information Center

McManus, Kimberly Ozella

2017-01-01

The purpose of this study was to measure and compare five preconditions for success of African American male community college students at community colleges by determining if there is a relationship between a) GPA and credits earned, utilizing Wood and Harris' (2012; 2016) Community College Survey of Men (CCSM, 2014) and Community College Success…

An iterative method for the Helmholtz equation

NASA Technical Reports Server (NTRS)

Bayliss, A.; Goldstein, C. I.; Turkel, E.

1983-01-01

An iterative algorithm for the solution of the Helmholtz equation is developed. The algorithm is based on a preconditioned conjugate gradient iteration for the normal equations. The preconditioning is based on an SSOR sweep for the discrete Laplacian. Numerical results are presented for a wide variety of problems of physical interest and demonstrate the effectiveness of the algorithm.

Mesenchymal Stem/Stromal Cells in Regenerative Medicine: Can Preconditioning Strategies Improve Therapeutic Efficacy?

PubMed

Schäfer, Richard; Spohn, Gabriele; Baer, Patrick C

2016-07-01

Mesenchymal stem/stromal cells (MSCs) are becoming increasingly important for the development of cell therapeutics in regenerative medicine. Featuring immunomodulatory potential as well as secreting a variety of trophic factors, MSCs showed remarkable therapeutic effects in numerous preclinical disease models. However, sustainable translation of MSC therapies to the clinic is hampered by heterogeneity of MSCs and non-standardized in vitro culture technologies. Moreover, potent MSC therapeutics require MSCs with maximum regenerative capacity. There is growing evidence that in vitro preconditioning strategies of MSCs can optimize their therapeutic potential. In the following we will discuss achievements and challenges of the development of MSC therapies in regenerative medicine highlighting specific in vitro preconditioning strategies prior to cell transplantation to increase their therapeutic efficacy.

HMC algorithm with multiple time scale integration and mass preconditioning

NASA Astrophysics Data System (ADS)

Urbach, C.; Jansen, K.; Shindler, A.; Wenger, U.

2006-01-01

We present a variant of the HMC algorithm with mass preconditioning (Hasenbusch acceleration) and multiple time scale integration. We have tested this variant for standard Wilson fermions at β=5.6 and at pion masses ranging from 380 to 680 MeV. We show that in this situation its performance is comparable to the recently proposed HMC variant with domain decomposition as preconditioner. We give an update of the "Berlin Wall" figure, comparing the performance of our variant of the HMC algorithm to other published performance data. Advantages of the HMC algorithm with mass preconditioning and multiple time scale integration are that it is straightforward to implement and can be used in combination with a wide variety of lattice Dirac operators.

On linearization and preconditioning for radiation diffusion coupled to material thermal conduction equations

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

Feng, Tao, E-mail: fengtao2@mail.ustc.edu.cn; Graduate School of China Academy Engineering Physics, Beijing 100083; An, Hengbin, E-mail: an_hengbin@iapcm.ac.cn

2013-03-01

Jacobian-free Newton–Krylov (JFNK) method is an effective algorithm for solving large scale nonlinear equations. One of the most important advantages of JFNK method is that there is no necessity to form and store the Jacobian matrix of the nonlinear system when JFNK method is employed. However, an approximation of the Jacobian is needed for the purpose of preconditioning. In this paper, JFNK method is employed to solve a class of non-equilibrium radiation diffusion coupled to material thermal conduction equations, and two preconditioners are designed by linearizing the equations in two methods. Numerical results show that the two preconditioning methods canmore » improve the convergence behavior and efficiency of JFNK method.« less

Finding Chemical Reaction Paths with a Multilevel Preconditioning Protocol

PubMed Central

2015-01-01

Finding transition paths for chemical reactions can be computationally costly owing to the level of quantum-chemical theory needed for accuracy. Here, we show that a multilevel preconditioning scheme that was recently introduced (Tempkin et al. J. Chem. Phys.2014, 140, 184114) can be used to accelerate quantum-chemical string calculations. We demonstrate the method by finding minimum-energy paths for two well-characterized reactions: tautomerization of malonaldehyde and Claissen rearrangement of chorismate to prephanate. For these reactions, we show that preconditioning density functional theory (DFT) with a semiempirical method reduces the computational cost for reaching a converged path that is an optimum under DFT by several fold. The approach also shows promise for free energy calculations when thermal noise can be controlled. PMID:25516726

Investigation of Reperfusion Injury and Ischemic Preconditioning in Microsurgry

PubMed Central

Wang, Wei Zhong

2008-01-01

Ischemia/reperfusion (I/R) is inevitable in many vascular and musculoskeletal traumas, diseases, free tissue transfers, and during time-consuming reconstructive surgeries in the extremities. Salvage of a prolonged ischemic extremity or flap still remains a challenge for the microvascular surgeon. One of the common complications after microsurgery is I/R-induced tissue death or I/R injury. Twenty years after the discovery, ischemic preconditioning (IPC) has emerged as a powerful method for attenuating I/R injury in a variety of organs or tissues. However, its therapeutic expectations still need to be fulfilled. In this article, the author reviews some important experimental evidences of I/R injury as well as preconditioning-induced protection in the fields relevant to microsurgery. PMID:18946882

Emotions in Depression: What Do We Really Know?

PubMed

Rottenberg, Jonathan

2017-05-08

Major depressive disorder is among the most common and costly of all mental health conditions, and in the last 20 years, emotional dysfunction has been increasingly seen as central to depression. Accordingly, research on emotions in depression has proceeded with fury. The urgency of the work has tempted investigators to issue premature declarations and to sometimes overlook theoretical and methodological challenges entailed in studying emotion. I report on what we have learned thus far about how depression influences emotional reactivity and emotion regulation, and also carefully demarcate the vast terrain of what we do not yet know. Ironically, an attitude of humility may enable the field to achieve the ambitious but elusive goal of developing a rich, contextually specific account of depression-related changes in emotional reactivity and regulation. Such an account is a precondition for using knowledge about emotion to intervene more effectively to reduce depression's worldwide burden.

Phosphodiesterase-5 inhibitor sildenafil preconditions adult cardiac myocytes against necrosis and apoptosis. Essential role of nitric oxide signaling.

PubMed

Das, Anindita; Xi, Lei; Kukreja, Rakesh C

2005-04-01

We investigated the effect of sildenafil in protection against necrosis or apoptosis in cardiomyocytes. Adult mouse ventricular myocytes were treated with sildenafil (1 or 10 microM) for 1 h before 40 min of simulated ischemia (SI). Necrosis was determined by trypan blue exclusion and lactate dehydrogenase release following SI alone or plus 1 or 18 h of reoxygenation (RO). Apoptosis was assessed by terminal deoxynucleotidyl transferase-mediated nick end labeling assay and mitochondrial membrane potential measured using a fluorescent probe 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolyl-carbocyanine iodide (JC-1). Sildenafil reduced necrosis as indicated by decrease in trypan blue-positive myocytes and leakage of lactate dehydrogenase compared with untreated cells after either SI or SI-RO. The number of terminal deoxynucleotidyl transferase-mediated nick end labeling-positive myocytes or loss of JC-1 fluorescence following SI and 18 h of RO was attenuated in the sildenafil-treated group with concomitant inhibition of caspase 3 activity. An early increase in Bcl-2 to Bax ratio with sildenafil treatment was also observed in myocytes after SI-RO. The increase of Bcl-2 expression by sildenafil was inhibited by nitric-oxide synthase (NOS) inhibitor, L-nitro-amino-methyl-ester. The drug also enhanced mRNA and protein content of inducible NOS (iNOS) and endothelial NOS (eNOS) in the myocytes. Sildenafil-induced protection against necrosis and apoptosis was absent in the myocytes derived from iNOS knock-out mice and was attenuated in eNOS knock-out myocytes. The up-regulation of Bcl-2 expression by sildenafil was also absent in iNOS-deficient myocytes. Reverse transcription-PCR, Western blots, and immunohistochemical assay confirmed the expression of phosphodiesterase-5 in mouse cardiomyocytes. These data provide strong evidence for a direct protective effect of sildenafil against necrosis and apoptosis through NO signaling pathway. The results may have possible therapeutic potential in preventing myocyte cell death following ischemia/reperfusion.

[Coenzyme Q10 enhances the expression of Bcl-2 and inhibits the expressions of Bax and GSK-3β in the hippocampus of rats exposed to ischemia/reperfusion injury].

PubMed

Tian, Shuang; Wang, Di; Li, Xiaodong; Tang, Jianjie; Han, Guang; Dai, Yongyi

2013-07-01

To investigate the effects of coenzyme Q10 pretreatment on the expressions of Bcl-2, Bax and glycogen synthase kinase-3β (GSK-3β) in rats suffering from ischemia/reperfusion injury. Thirty-six adult male SD rats were randomly assigned into 3 groups: sham-operated group (sham), ischemia/reperfusion group (I/R) and coenzyme Q10 preconditioning group (Q10). Focal cerebral ischemia/reperfusion models were established in experimental rats by blocking middle cerebral artery with suture. Histological changes of hippocampal neurons were observed by HE staining. The expressions of Bcl-2, Bax and GSK-3β were detected by immunohistochemistry and Western blotting. Immunohistochemistry showed that the percentage of Bcl-2 positive cells increased in the hippocampus, while the percentages of Bax and GSK-3β positive cells decreased in Q10 group compared with I/R group. Western blotting revealed that the expression level of Bcl-2 was higher and the expression levels of Bax and GSK-3β were lower in Q10 group than in I/R group. There were significant differences between the two groups (P<0.05). Coenzyme Q10 promoted the expression of Bcl-2 and suppressed the expressions of Bax and GSK-3β in the hippocampus of rats exposed to cerebral ischemia/reperfusion.

Accounting for failure: risk-based regulation and the problems of ensuring healthcare quality in the NHS

PubMed Central

Beaussier, Anne-Laure; Demeritt, David; Griffiths, Alex; Rothstein, Henry

2016-01-01

In this paper, we examine why risk-based policy instruments have failed to improve the proportionality, effectiveness, and legitimacy of healthcare quality regulation in the National Health Service (NHS) in England. Rather than trying to prevent all possible harms, risk-based approaches promise to rationalise and manage the inevitable limits of what regulation can hope to achieve by focusing regulatory standard-setting and enforcement activity on the highest priority risks, as determined through formal assessments of their probability and consequences. As such, risk-based approaches have been enthusiastically adopted by healthcare quality regulators over the last decade. However, by drawing on historical policy analysis and in-depth interviews with 15 high-level UK informants in 2013–2015, we identify a series of practical problems in using risk-based policy instruments for defining, assessing, and ensuring compliance with healthcare quality standards. Based on our analysis, we go on to consider why, despite a succession of failures, healthcare regulators remain committed to developing and using risk-based approaches. We conclude by identifying several preconditions for successful risk-based regulation: goals must be clear and trade-offs between them amenable to agreement; regulators must be able to reliably assess the probability and consequences of adverse outcomes; regulators must have a range of enforcement tools that can be deployed in proportion to risk; and there must be political tolerance for adverse outcomes. PMID:27499677

Accounting for failure: risk-based regulation and the problems of ensuring healthcare quality in the NHS.

PubMed

Beaussier, Anne-Laure; Demeritt, David; Griffiths, Alex; Rothstein, Henry

2016-05-18

In this paper, we examine why risk-based policy instruments have failed to improve the proportionality, effectiveness, and legitimacy of healthcare quality regulation in the National Health Service (NHS) in England. Rather than trying to prevent all possible harms, risk-based approaches promise to rationalise and manage the inevitable limits of what regulation can hope to achieve by focusing regulatory standard-setting and enforcement activity on the highest priority risks, as determined through formal assessments of their probability and consequences. As such, risk-based approaches have been enthusiastically adopted by healthcare quality regulators over the last decade. However, by drawing on historical policy analysis and in-depth interviews with 15 high-level UK informants in 2013-2015, we identify a series of practical problems in using risk-based policy instruments for defining, assessing, and ensuring compliance with healthcare quality standards. Based on our analysis, we go on to consider why, despite a succession of failures, healthcare regulators remain committed to developing and using risk-based approaches. We conclude by identifying several preconditions for successful risk-based regulation: goals must be clear and trade-offs between them amenable to agreement; regulators must be able to reliably assess the probability and consequences of adverse outcomes; regulators must have a range of enforcement tools that can be deployed in proportion to risk; and there must be political tolerance for adverse outcomes.

A-type potassium channels differentially tune afferent pathways from rat solitary tract nucleus to caudal ventrolateral medulla or paraventricular hypothalamus

PubMed Central

Bailey, T W; Hermes, S M; Whittier, K L; Aicher, S A; Andresen, M C

2007-01-01

The solitary tract nucleus (NTS) conveys visceral information to diverse central networks involved in homeostatic regulation. Although afferent information content arriving at various CNS sites varies substantially, little is known about the contribution of processing within the NTS to these differences. Using retrograde dyes to identify specific NTS projection neurons, we recently reported that solitary tract (ST) afferents directly contact NTS neurons projecting to caudal ventrolateral medulla (CVLM) but largely only indirectly contact neurons projecting to the hypothalamic paraventricular nucleus (PVN). Since intrinsic properties impact information transmission, here we evaluated potassium channel expression and somatodendritic morphology of projection neurons and their relation to afferent information output directed to PVN or CVLM pathways. In slices, tracer-identified projection neurons were classified as directly or indirectly (polysynaptically) coupled to ST afferents by EPSC latency characteristics (directly coupled, jitter < 200 μs). In each neuron, voltage-dependent potassium currents (IK) were evaluated and, in representative neurons, biocytin-filled structures were quantified. Both CVLM- and PVN-projecting neurons had similar, tetraethylammonium-sensitive IK. However, only PVN-projecting NTS neurons displayed large transient, 4aminopyridine-sensitive, A-type currents (IKA). PVN-projecting neurons had larger cell bodies with more elaborate dendritic morphology than CVLM-projecting neurons. ST shocks faithfully (> 75%) triggered action potentials in CVLM-projecting neurons but spike output was uniformly low (< 20%) in PVN-projecting neurons. Pre-conditioning hyperpolarization removed IKA inactivation and attenuated ST-evoked spike generation along PVN but not CVLM pathways. Thus, multiple differences in structure, organization, synaptic transmission and ion channel expression tune the overall fidelity of afferent signals that reach these destinations. PMID:17510187

Protective effect of Ginkgo biloba leaves extract, EGb761, on myocardium injury in ischemia reperfusion rats via regulation of TLR-4/NF-κB signaling pathway.

PubMed

Tang, Yuping; Zhou, Guisheng; Yao, Lijun; Xue, Ping; Yu, Danhong; Xu, Renjie; Shi, Wen; Yao, Xin; Yan, Zhaowei; Duan, Jin-Ao

2017-10-17

Beneficial actions of EGb 761 against ischemia/reperfusion (I/R) injury in lung, brain and renal ischemia have been described. However, the relationship between EGb 761 and signal molecules in myocardial ischemia reperfusion has not been well elucidated. In this study, we investigated the effects and mechanism of EGb 761 preconditioning on anti-myocardial I/R injuries in vivo . Meanwhile, their potential anti-oxidative stress and anti-inflammation effect were assessed. Hemodynamic parameters were monitored as left ventricular systolic pressure, LV end-diastolic pressure and maximal rate of increase and decrease of left ventricular pressure (dP/dtmax). The oxidative stress indicators and inflammatory factors were also evaluated. Western blot method was used for analysis of toll-like receptor 4 (TLR4), p-TLR4, nuclear factor-κB (NF-κB), p-NF-κB p65, Bax and Bcl-2 protein expressions. EGb 761 significantly improved cardiac function, decreased levels of creatine kinase, aspartate aminotransferase and lactate dehydrogenase. EGb 761 also restrained the oxidative stress related to myocardial ischemia injury as evidenced by decreased malondialdehyde, superoxide dismutase, catalase, glutathione-peroxidase, glutathione reductase activity. Meanwhile, the inflammatory cascade was inhibited as evidenced by decreased cytokines such as tumor necrosis factor-α, interleukin-6 and interleukin-1β. Our results still showed that EGb 761 pretreatment significantly decrease the level of cleaved Bax, and increase the level of Bcl-2 in rats subjected to I/R injury. Simultaneously, the expressions of myocardial TLR4 and NF-κB were significantly decreased. It can be concluded that EGb 761 pretreatment was protected against myocardium I/R injury by decreasing oxidative stress, repressing inflammatory cascade in vivo and inhibiting TLR4/NF-κB pathway.

Effect of preconditioning on silver leaching and bromide removal properties of silver-impregnated activated carbon (SIAC).

PubMed

Rajaeian, Babak; Allard, Sébastien; Joll, Cynthia; Heitz, Anna

2018-07-01

Silver impregnated activated carbon (SIAC) has been found to be effective in mitigating the formation of brominated-disinfection by products during drinking water treatment. However, there are still uncertainties regarding its silver leaching properties, and strategies for the prevention of silver leaching have remained elusive. This study focused on the evaluation of one type of commercially available SIAC for its ability to remove bromide while minimising silver leaching from the material. Both synthetic and real water matrices were tested. Depending on solution pH, it was found that changing the surface charge properties of SIAC, as measured by the point of zero charge pH, can result in additional bromide removal while minimising the extent of silver leaching. To better understand the mechanism of silver leaching from the SIAC, eight preconditioning environments, i.e. variable pH and ionic strength were tested for a fixed amount of SIAC and two preconditioning environments were selected for a more detailed investigation. Experiments carried out in synthetic water showed that preconditioning at pH 10.4 did not deteriorate the capacity of SIAC to remove bromide, but significantly decreased the release of silver in the form of ionic silver (Ag + ), silver bromide (AgBr) and silver chloride (AgCl) from 40% for the pristine to 3% for the treated SIAC. This was confirmed using a groundwater sample. These results suggest that preconditioned SIAC has the potential to be an effective method for bromide removal with minimised silver leaching in a long-term field application for drinking water production. Copyright © 2018 Elsevier Ltd. All rights reserved.

Sleep Is Critical for Remote Preconditioning-Induced Neuroprotection.

PubMed

Brager, Allison J; Yang, Tao; Ehlen, J Christopher; Simon, Roger P; Meller, Robert; Paul, Ketema N

2016-11-01

Episodes of brief limb ischemia (remote preconditioning) in mice induce tolerance to modeled ischemic stroke (focal brain ischemia). Since stroke outcomes are in part dependent on sleep-wake history, we sought to determine if sleep is critical for the neuroprotective effect of limb ischemia. EEG/EMG recording electrodes were implanted in mice. After a 24 h baseline recording, limb ischemia was induced by tightening an elastic band around the left quadriceps for 10 minutes followed by 10 minutes of release for two cycles. Two days following remote preconditioning, a second 24 h EEG/EMG recording was completed and was immediately followed by a 60-minute suture occlusion of the middle cerebral artery (modeled ischemic stroke). This experiment was then repeated in a model of circadian and sleep abnormalities ( Bmal1 knockout [KO] mice sleep 2 h more than wild-type littermates). Brain infarction was determined by vital dye staining, and sleep was assessed by trained identification of EEG/EMG recordings. Two days after limb ischemia, wild-type mice slept an additional 2.4 h. This additional sleep was primarily comprised of non-rapid eye movement (NREM) sleep during the middle of the light-phase (i.e., naps). Repeating the experiment but preventing increases in sleep after limb ischemia abolished tolerance to ischemic stroke. In Bmal1 knockout mice, remote preconditioning did not increase daily sleep nor provide tolerance to subsequent focal ischemia. These results suggest that sleep induced by remote preconditioning is both sufficient and necessary for its neuroprotective effects on stroke outcome. © 2016 Associated Professional Sleep Societies, LLC.

Signal transduction of flumazenil-induced preconditioning in myocytes.

PubMed

Yao, Z; McPherson, B C; Liu, H; Shao, Z; Li, C; Qin, Y; Vanden Hoek, T L; Becker, L B; Schumacker, P T

2001-03-01

The objective of this study was to examine the role of oxygen radicals, protein kinase C (PKC), and ATP-sensitive K(+) (K(ATP)) channels in mediating flumazenil-produced preconditioning. Chick cardiomyocyte death was quantified using propidium iodide, and oxygen radical generation was assessed using 2',7'-dichlorofluorescin oxidation. Preconditioning was initiated with 10 min of ischemia followed by 10 min of reoxygenation. Alternatively, flumazenil was infused for 10 min and removed 10 min before ischemia. Flumazenil (10 microM) and preconditioning increased oxygen radicals [1,693 +/- 101 (n = 3) and 1,567 +/- 98 (n = 3), respectively, vs. 345 +/- 53 (n = 3) in control] and reduced cell death similarly [22 +/- 3% (n = 5) and 18 +/- 2% (n = 6), respectively, vs. controls 49 +/- 5% (n = 8)]. Protection and increased oxygen radicals by flumazenil were abolished by pretreatment with the antioxidant thiol reductant 2-mercaptopropionyl glycine (800 microM; 52 +/- 10%, n = 6). Specific PKC inhibitors Go-6976 (0.1 microM) and chelerythrine (2 microM), given during ischemia and reoxygenation, blocked flumazenil-produced protection (47 +/- 5%, n = 6). The PKC activator phorbol 12-myristate 13-acetate (0.2 microM), given during ischemia and reoxygenation, reduced cell death similarly to that with flumazenil [17 +/- 4% (n = 6) and 22 +/- 3% (n = 5)]. Finally, 5-hydroxydecanoate (1 mM), a selective mitochondrial K(ATP) channel antagonist given during ischemia and reoxygenation, abolished the protection of flumazenil and phorbol 12-myristate 13-acetate. Thus flumazenil mimics preconditioning to reduce cell death in cardiomyocytes. Oxygen radicals activate mitochondrial K(ATP) channels via PKC during the process.

Human Bone Marrow-Derived Mesenchymal Stem Cells Display Enhanced Clonogenicity but Impaired Differentiation With Hypoxic Preconditioning

PubMed Central

Boyette, Lisa B.; Creasey, Olivia A.; Guzik, Lynda; Lozito, Thomas

2014-01-01

Stem cells are promising candidate cells for regenerative applications because they possess high proliferative capacity and the potential to differentiate into other cell types. Mesenchymal stem cells (MSCs) are easily sourced but do not retain their proliferative and multilineage differentiative capabilities after prolonged ex vivo propagation. We investigated the use of hypoxia as a preconditioning agent and in differentiating cultures to enhance MSC function. Culture in 5% ambient O2 consistently enhanced clonogenic potential of primary MSCs from all donors tested. We determined that enhanced clonogenicity was attributable to increased proliferation, increased vascular endothelial growth factor secretion, and increased matrix turnover. Hypoxia did not impact the incidence of cell death. Application of hypoxia to osteogenic cultures resulted in enhanced total mineral deposition, although this effect was detected only in MSCs preconditioned in normoxic conditions. Osteogenesis-associated genes were upregulated in hypoxia, and alkaline phosphatase activity was enhanced. Adipogenic differentiation was inhibited by exposure to hypoxia during differentiation. Chondrogenesis in three-dimensional pellet cultures was inhibited by preconditioning with hypoxia. However, in cultures expanded under normoxia, hypoxia applied during subsequent pellet culture enhanced chondrogenesis. Whereas hypoxic preconditioning appears to be an excellent way to expand a highly clonogenic progenitor pool, our findings suggest that it may blunt the differentiation potential of MSCs, compromising their utility for regenerative tissue engineering. Exposure to hypoxia during differentiation (post-normoxic expansion), however, appears to result in a greater quantity of functional osteoblasts and chondrocytes and ultimately a larger quantity of high-quality differentiated tissue. PMID:24436440

Exercise and Cardiac Preconditioning Against Ischemia Reperfusion Injury

PubMed Central

Quindry, John C; Hamilton, Karyn L

2013-01-01

Cardiovascular disease (CVD), including ischemia reperfusion (IR) injury, remains a major cause of morbidity and mortality in industrialized nations. Ongoing research is aimed at uncovering therapeutic interventions against IR injury. Regular exercise participation is recognized as an important lifestyle intervention in the prevention and treatment of CVD and IR injury. More recent understanding reveals that moderate intensity aerobic exercise is also an important experimental model for understanding the cellular mechanisms of cardioprotection against IR injury. An important discovery in this regard was the observation that one-to-several days of exercise will attenuate IR injury. This phenomenon has been observed in young and old hearts of both sexes. Due to the short time course of exercise induced protection, IR injury prevention must be mediated by acute biochemical alterations within the myocardium. Research over the last decade reveals that redundant mechanisms account for exercise induced cardioprotection against IR. While much is now known about exercise preconditioning against IR injury, many questions remain. Perhaps most pressing, is what mechanisms mediate cardioprotection in aged hearts and what sex-dependent differences exist. Given that that exercise preconditioning is a polygenic effect, it is likely that multiple mediators of exercise induced cardioprotection have yet to be uncovered. Also unknown, is whether post translational modifications due to exercise are responsible for IR injury prevention. This review will provide an overview the major mechanisms of IR injury and exercise preconditioning. The discussion highlights many promising avenues for further research and describes how exercise preconditioning may continue to be an important scientific paradigm in the translation of cardioprotection research to the clinic. PMID:23909636

Low-energy shock wave preconditioning reduces renal ischemic reperfusion injury caused by renal artery occlusion.

PubMed

Xue, Yuquan; Xu, Zhibin; Chen, Haiwen; Gan, Weimin; Chong, Tie

2017-07-01

To evaluate whether low energy shock wave preconditioning could reduce renal ischemic reperfusion injury caused by renal artery occlusion. The right kidneys of 64 male Sprague Dawley rats were removed to establish an isolated kidney model. The rats were then divided into four treatment groups: Group 1 was the sham treatment group; Group 2, received only low-energy (12 kv, 1 Hz, 200 times) shock wave preconditioning; Group 3 received the same low-energy shock wave preconditioning as Group 2, and then the left renal artery was occluded for 45 minutes; and Group 4 had the left renal artery occluded for 45 minutes. At 24 hours and one-week time points after reperfusion, serum inducible nitric oxide synthase (iNOS), neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), creatinine (Cr), and cystatin C (Cys C) levels were measured, malondialdehyde (MDA) in kidney tissue was detected, and changes in nephric morphology were evaluated by light and electron microscopy. Twenty-four hours after reperfusion, serum iNOS, NGAL, Cr, Cys C, and MDA levels in Group 3 were significantly lower than those in Group 4; light and electron microscopy showed that the renal tissue injury in Group 3 was significantly lighter than that in Group 4. One week after reperfusion, serum NGAL, KIM-1, and Cys C levels in Group 3 were significantly lower than those in Group 4. Low-energy shock wave preconditioning can reduce renal ischemic reperfusion injury caused by renal artery occlusion in an isolated kidney rat model.

The New LMK Primary Standard for Dew-Point Sensor Calibration: Evaluation of the High-Range Saturator Efficiency

NASA Astrophysics Data System (ADS)

Hudoklin, Domen; Drnovšek, Janko

2008-10-01

In the field of hygrometry, a primary dew-point standard can be realized according to several proven principles, such as single-pressure (1-P), two-pressure (2-P), or divided flow. Different realizations have been introduced by various national laboratories, each resulting in a stand-alone complex generation system. Recent trends in generator design favor the single-pressure principle without recirculation because it promises theoretically lower uncertainty and because it avoids problems regarding the leak tightness of the recirculation. Instead of recirculation, the efficiency of saturation, the key factor, is increased by preconditioning the inlet gas entering the saturator. For preconditioning, a presaturator or purifier is used to bring the dew point of the inlet stream close to the saturator temperature. The purpose of the paper is to identify the minimum requirements for the preconditioning system and the main saturator to assure efficient saturation for the LMK generator. Moreover, the aim is also to find out if the preconditioning system can be avoided despite the rather simple construction of the main saturator. If this proves to be the case, the generator design can be simplified while maintaining an accurate value of the generated dew point. Experiments were carried out within the scope of improving our existing primary generator in the above-ambient dew-point range up to +70°C. These results show the generated dew point is within the measurement uncertainty for any dew-point value of the inlet gas. Thus, the preconditioning subsystem can be avoided, which leads to a simplified generator design.

Possible role of thromboxane A2 in remote hind limb preconditioning-induced cardioprotection.

PubMed

Sharma, Roohani; Randhawa, Puneet Kaur; Singh, Nirmal; Jaggi, Amteshwar Singh

2016-01-01

Remote hind limb preconditioning (RIPC) is a protective strategy in which short episodes of ischemia and reperfusion in a remote organ (hind limb) protects the target organ (heart) against sustained ischemic reperfusion injury. The present study was designed to investigate the possible role of thromboxane A2 in RIPC-induced cardioprotection in rats. Remote hind limb preconditioning was performed by four episodes of 5 min of inflation and 5 min of deflation of pressure cuff. Occlusion of the hind limb with blood pressure cuff is most feasible, non-invasive, clinically relevant, and safe method for inducing RIPC. Isolated rat hearts were perfused on Langendorff apparatus and were subjected to global ischemia for 30 min followed by 120-min reperfusion. The levels of lactate dehydrogenase (LDH) and creatine kinase (CK) were measured in coronary effluent to assess the degree of myocardial injury. The extent of myocardial infarct size along with the functional parameters including left ventricular developed pressure (LVDP), dp/dtmax, and dp/dtmin were also measured. Ozagrel (thromboxane synthase inhibitor) and seratrodast (thromboxane A2 receptor antagonist) were employed as pharmacological modulators of thromboxane A2. Remote hind limb preconditioning significantly attenuated ischemia/reperfusion-induced myocardial injury and produced cardioprotective effects. However, administration of ozagrel and seratrodast completely abolished the cardioprotective effects of RIPC suggesting the key role of thromboxane A2 in RIPC-induced cardioprotection. It may be concluded that brief episodes of preconditioning ischemia and reperfusion activates the thromboxane synthase enzyme that produces thromboxane A2, which may elicit cardioprotection either involving humoral or neurogenic pathway.

Modeling of frequency-domain scalar wave equation with the average-derivative optimal scheme based on a multigrid-preconditioned iterative solver

NASA Astrophysics Data System (ADS)

Cao, Jian; Chen, Jing-Bo; Dai, Meng-Xue

2018-01-01

An efficient finite-difference frequency-domain modeling of seismic wave propagation relies on the discrete schemes and appropriate solving methods. The average-derivative optimal scheme for the scalar wave modeling is advantageous in terms of the storage saving for the system of linear equations and the flexibility for arbitrary directional sampling intervals. However, using a LU-decomposition-based direct solver to solve its resulting system of linear equations is very costly for both memory and computational requirements. To address this issue, we consider establishing a multigrid-preconditioned BI-CGSTAB iterative solver fit for the average-derivative optimal scheme. The choice of preconditioning matrix and its corresponding multigrid components is made with the help of Fourier spectral analysis and local mode analysis, respectively, which is important for the convergence. Furthermore, we find that for the computation with unequal directional sampling interval, the anisotropic smoothing in the multigrid precondition may affect the convergence rate of this iterative solver. Successful numerical applications of this iterative solver for the homogenous and heterogeneous models in 2D and 3D are presented where the significant reduction of computer memory and the improvement of computational efficiency are demonstrated by comparison with the direct solver. In the numerical experiments, we also show that the unequal directional sampling interval will weaken the advantage of this multigrid-preconditioned iterative solver in the computing speed or, even worse, could reduce its accuracy in some cases, which implies the need for a reasonable control of directional sampling interval in the discretization.

Enhanced shock wave generation via pre-breakdown acceleration using water electrolysis in negative streamer pulsed spark discharges

NASA Astrophysics Data System (ADS)

Lee, Kern; Chung, Kyoung-Jae; Hwang, Y. S.

2018-03-01

This paper presents a method for enhancement of shock waves generated from underwater pulsed spark discharges with negative (anode-directed) subsonic streamers, for which the pre-breakdown process is accelerated by preconditioning a gap with water electrolysis. Hydrogen microbubbles are produced at the cathode by the electrolysis and move towards the anode during the preconditioning phase. The numbers and spatial distributions of the microbubbles vary with the amplitude and duration of each preconditioning pulse. Under our experimental conditions, the optimum pulse duration is determined to be ˜250 ms at a pulse voltage of 400 V, where the buoyancy force overwhelms the electric force and causes the microbubbles to be swept out from the water gap. When a high-voltage pulse is applied to the gap just after the preconditioning pulse, the pre-breakdown process is significantly accelerated in the presence of the microbubbles. At the optimum preconditioning pulse duration, the average breakdown delay is reduced by 87% and, more importantly, the energy consumed during the pre-breakdown period decreases by 83%. This reduced energy consumption during the pre-breakdown period, when combined with the morphological advantages of negative streamers, such as thicker and longer stalks, leads to a significant improvement in the measured peak pressure (˜40%) generated by the underwater pulsed spark discharge. This acceleration of pre-breakdown using electrolysis overcomes the biggest drawback of negative subsonic discharges, which is slow vapor bubble formation due to screening effects, and thus enhances the efficiency of the shock wave generation process using pulsed spark discharges in water.

HSP70.1 AND -70.3 ARE REQUIRED FOR LATE-PHASE PROTECTION INDUCED BY ISCHEMIC PRECONDITIONING OF MOUSE HEARTS

EPA Science Inventory

Heat-Shock Proteins 70.1 and 70.3 Are Required for Late-phase Protection
Induced by Ischemic Preconditioning of the Mouse Heart
Craig R. Hampton 1 , Akira Shimamoto 1 , Christine L. Rothnie 1 , Jeaneatte Griscavage-Ennis 1 ,
Albert Chong 1 , David J. Dix 2 , Edward D. Ve...

Audiovisual preconditioning enhances the efficacy of an anatomical dissection course: A randomised study.

PubMed

Collins, Anne M; Quinlan, Christine S; Dolan, Roisin T; O'Neill, Shane P; Tierney, Paul; Cronin, Kevin J; Ridgway, Paul F

2015-07-01

The benefits of incorporating audiovisual materials into learning are well recognised. The outcome of integrating such a modality in to anatomical education has not been reported previously. The aim of this randomised study was to determine whether audiovisual preconditioning is a useful adjunct to learning at an upper limb dissection course. Prior to instruction participants completed a standardised pre course multiple-choice questionnaire (MCQ). The intervention group was subsequently shown a video with a pre-recorded commentary. Following initial dissection, both groups completed a second MCQ. The final MCQ was completed at the conclusion of the course. Statistical analysis confirmed a significant improvement in the performance in both groups over the duration of the three MCQs. The intervention group significantly outperformed their control group counterparts immediately following audiovisual preconditioning and in the post course MCQ. Audiovisual preconditioning is a practical and effective tool that should be incorporated in to future course curricula to optimise learning. Level of evidence This study appraises an intervention in medical education. Kirkpatrick Level 2b (modification of knowledge). Copyright © 2015 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Substitution of Hospital Care with Primary Care: Defining the Conditions of Primary Care Plus

PubMed Central

Kroese, Mariëlle Elisabeth Aafje Lydia; Spreeuwenberg, Marieke Dingena; Elissen, Arianne Mathilda Josephus; Meerlo, Ronald Johan; Hanraets, Monique Margaretha Henriëtte; Ruwaard, Dirk

2016-01-01

Objective: To analyse barriers and facilitators in substituting hospital care with primary care to define preconditions for successful implementation. Methods: A descriptive feasibility study was performed to collect information on the feasibility of substituting hospital care with primary care. General practitioners were able to refer patients, about whom they had doubts regarding diagnosis, treatment and/or the need to refer to hospital care, to medical specialists who performed low-complex consultations at general practitioner practices. Qualitative data were collected through interviews with general practitioners and medical specialists, focus groups and notes from meetings in the Netherlands between April 2013 and January 2014. Data were analysed using a conventional content analysis which resulted in categorised barriers, facilitators and policy adjustments, after which preconditions were formulated. Results: The most important preconditions were make arrangements on governmental level, arrange a collective integrated IT-system, determine the appropriate profile for medical specialists, design a referral protocol for eligible patients, arrange deliberation possibilities for general practitioners and medical specialists and formulate a diagnostic protocol. Conclusions: The barriers, facilitators and formulated preconditions provided relevant input to change the design of substituting hospital care with primary care. PMID:27616956

Osteogenic potential of human adipose-tissue-derived mesenchymal stromal cells cultured on 3D-printed porous structured titanium.

PubMed

Lewallen, Eric A; Jones, Dakota L; Dudakovic, Amel; Thaler, Roman; Paradise, Christopher R; Kremers, Hilal M; Abdel, Matthew P; Kakar, Sanjeev; Dietz, Allan B; Cohen, Robert C; Lewallen, David G; van Wijnen, Andre J

2016-05-01

Integration of porous metal prosthetics, which restore form and function of irreversibly damaged joints, into remaining healthy bone is critical for implant success. We investigated the biological properties of adipose-tissue-derived mesenchymal stromal/stem cells (AMSCs) and addressed their potential to alter the in vitro microenvironment of implants. We employed human AMSCs as a practical source for musculoskeletal applications because these cells can be obtained in large quantities, are multipotent, and have trophic paracrine functions. AMSCs were cultured on surgical-grade porous titanium disks as a model for orthopedic implants. We monitored cell/substrate attachment, cell proliferation, multipotency, and differentiation phenotypes of AMSCs upon osteogenic induction. High-resolution scanning electron microscopy and histology revealed that AMSCs adhere to the porous metallic surface. Compared to standard tissue culture plastic, AMSCs grown in the porous titanium microenvironment showed differences in temporal expression for genes involved in cell cycle progression (CCNB2, HIST2H4), extracellular matrix production (COL1A1, COL3A1), mesenchymal lineage identity (ACTA2, CD248, CD44), osteoblastic transcription factors (DLX3, DLX5, ID3), and epigenetic regulators (EZH1, EZH2). We conclude that metal orthopedic implants can be effectively seeded with clinical-grade stem/stromal cells to create a pre-conditioned implant. Copyright © 2016 Elsevier B.V. All rights reserved.

A new flavonoid glycoside (APG) isolated from Clematis tangutica attenuates myocardial ischemia/reperfusion injury via activating PKCε signaling.

PubMed

Zhu, Yanrong; Di, Shouyin; Hu, Wei; Feng, Yingda; Zhou, Qing; Gong, Bing; Tang, Xinlong; Liu, Juntian; Zhang, Wei; Xi, Miaomiao; Jiang, Lin; Guo, Chao; Cao, Jingyi; Fan, Chongxi; Ma, Zhiqiang; Yang, Yang; Wen, Aidong

2017-03-01

Clematis tangutica has been shown to be beneficial for the heart; however, the mechanism of this effectremains unknown. Apigenin-7-O-β-D-(-6″-p-coumaroyl)-glucopyranoside (APG) is a new flavonoid glycoside isolated from Clematis tangutica. This study investigates the effects of APG on myocardial ischemia/reperfusion (IR) injury (IRI). An IRI model of primary myocardial cells and mice was used in this study. Compared with the IR group, APG preconditioning is protective against IRI in primary myocardial cells and in mice hearts in a dose-dependent manner. The cardioprotective mechanisms of APG may involve a significant PKCε translocation into the mitochondria and an activation of the Nrf2/HO-1 pathway, which respectively suppressesmitochondrial oxidative stress and inhibits apoptosis. In addition, PKCε-targeted siRNA and a PKCε specialized inhibitor (ε-V1-2) were used to inhibit PKCε expression and activity. The inhibition of PKCε reversed the cardioprotective effect of APG, with an inhibition of Nrf2/HO-1 activation and increased mitochondrial oxidative stress and cardiomyocyte apoptosis. In conclusion, PKCε activation plays an important role in the cardioprotective effects of APG. PKCε activation induced by APG preconditioning reduces mitochondrial oxidative stress and promotes Nrf2/HO-1-mediated anti-apoptosis signaling. Copyright © 2016 Elsevier B.V. All rights reserved.

Short-term preconditioning enhances the therapeutic potential of adipose-derived stromal/stem cell-conditioned medium in cisplatin-induced acute kidney injury.

PubMed

Overath, Jürgen M; Gauer, Stefan; Obermüller, Nicholas; Schubert, Ralf; Schäfer, Richard; Geiger, Helmut; Baer, Patrick C

2016-03-15

The development of new strategies to preserve renal function after acute kidney injury (AKI) is necessary due to limited clinical intervention options. The organ-protective effects of mesenchymal stromal/stem cells (MSCs) and their conditioned medium (CM) have been investigated demonstrating that both separately promoted tubular recovery and ameliorated the outcome of AKI. Nevertheless, strategies to optimise the regenerative potential of both are highly needed. Here we investigated the effects of CM from adipose-derived MSCs (ASCs) preincubated in a hypoxic environment (Hyp). Protective factors were investigated by PCR analysis and a protein array in vitro. The expression of 64 of the 308 proteins assayed was found to be more than two-fold increased after Hyp. CM of Hyp-pretreated ASCs (pCM) was used to enhance regeneration in a mouse model of cisplatin-induced AKI (cisAKI). Renal function was assessed by measurements of markers for AKI and serum cytokine levels. The pCM significantly ameliorated serum creatinine and neutrophil gelatinase-associated lipocalin values, and also the levels of inflammatory cytokines IL-1β and IL-6 in the serum of mice with AKI. Our work clearly showed that a Hyp preconditioning significantly increases the release of protective factors in ASCs and enhances the therapeutic effects of CM in cisAKI in mice. Copyright © 2016 Elsevier Inc. All rights reserved.

Alterations of hypoxia-inducible factor-1 alpha in the hippocampus of mice acutely and repeatedly exposed to hypoxia.

PubMed

Shao, Guo; Gao, Cui-Ying; Lu, Guo-Wei

2005-01-01

This work aims at investigating the effects of hypoxic preconditioning on hypoxia-inducible factor-1 alpha (HIF-1alpha) expression in the hippocampus of mice during acute and repeated hypoxic exposures. The mice were randomly divided into three groups and exposed, respectively, to hypoxia for 4 runs (group H4), 1 run (group H1), and 0 run (group H0). Reverse transcription-polymerase chain reaction (RT-PCR), Western blot, electrophoretic mobility shift assay (EMSA), and chromatin immunoprecipitation were used to examine the HIF-1alpha responses in the mouse hippocampus following exposure to hypoxia. The tolerance of mice to hypoxia increased significantly following acute and repetitive exposure to autoprogressive hypoxia. Total mRNA, total protein, and nuclear protein were extracted from the hippocampus for RT-PCR, Western blot, and EMSA, respectively. The HIF-1alpha mRNA levels were found to be increased in group H1 and decreased in group H4. The HIF-1alpha protein levels and HIF-1 DNA-binding activities were increased in group H1 and markedly increased in group H4. One of the HIF-1 target genes, vascular endothelial growth factor, increased in group H4. HIF-1 activation is thought to be involved in the protection of the brain of hypoxic preconditioned mice. Copyright 2005 S. Karger AG, Basel

Effect of hypercholesterolaemia on myocardial function, ischaemia–reperfusion injury and cardioprotection by preconditioning, postconditioning and remote conditioning

PubMed Central

Iliodromitis, Efstathios K; Lazou, Antigone; Görbe, Anikó; Giricz, Zoltán; Schulz, Rainer

2017-01-01

Hypercholesterolaemia is considered to be a principle risk factor for cardiovascular disease, having direct negative effects on the myocardium itself, in addition to the development of atherosclerosis. Since hypercholesterolaemia affects the global cardiac gene expression profile, among many other factors, it results in increased myocardial oxidative stress, mitochondrial dysfunction and inflammation triggered apoptosis, all of which may account for myocardial dysfunction and increased susceptibility of the myocardium to infarction. In addition, numerous experimental and clinical studies have revealed that hyperlcholesterolaemia may interfere with the cardioprotective potential of conditioning mechanisms. Although not fully elucidated, the underlying mechanisms for the lost cardioprotection in hypercholesterolaemic animals have been reported to involve dysregulation of the endothelial NOS‐cGMP, reperfusion injury salvage kinase, peroxynitrite‐MMP2 signalling pathways, modulation of ATP‐sensitive potassium channels and apoptotic pathways. In this review article, we summarize the current knowledge on the effect of hypercholesterolaemia on the non‐ischaemic and ischaemic heart as well as on the cardioprotection induced by drugs or ischaemic preconditioning, postconditioning and remote conditioning. Future perspectives concerning the mechanisms and the design of preclinical and clinical trials are highlighted. Linked Articles This article is part of a themed section on Redox Biology and Oxidative Stress in Health and Disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.12/issuetoc PMID:28060997

Chronic shear induces caveolae formation and alters ERK and Akt responses in endothelial cells

NASA Technical Reports Server (NTRS)

Boyd, Nolan L.; Park, Heonyong; Yi, Hong; Boo, Yong Chool; Sorescu, George P.; Sykes, Michelle; Jo, Hanjoong

2003-01-01

Caveolae are plasmalemmal domains enriched with cholesterol, caveolins, and signaling molecules. Endothelial cells in vivo are continuously exposed to shear conditions, and their caveolae density and location may be different from that of static cultured cells. Here, we show that chronic shear exposure regulates formation and localization of caveolae and caveolin-1 in bovine aortic endothelial cells (BAEC). Chronic exposure (1 or 3 days) of BAEC to laminar shear increased the total number of caveolae by 45-48% above static control. This increase was due to a rise in the luminal caveolae density without changing abluminal caveolae numbers or increasing caveolin-1 mRNA and protein levels. Whereas some caveolin-1 was found in the plasma membrane in static-cultured cells, it was predominantly localized in the Golgi. In contrast, chronic shear-exposed cells showed intense caveolin-1 staining in the luminal plasma membrane with minimum Golgi association. The preferential luminal localization of caveolae may play an important role in endothelial mechanosensing. Indeed, we found that chronic shear exposure (preconditioning) altered activation patterns of two well-known shear-sensitive signaling molecules (ERK and Akt) in response to a step increase in shear stress. ERK activation was blunted in shear preconditioned cells, whereas the Akt response was accelerated. These results suggest that chronic shear stimulates caveolae formation by translocating caveolin-1 from the Golgi to the luminal plasma membrane and alters cell signaling responses.

Temporal and genetic influences on protection against noise-induced hearing loss by hypoxic preconditioning in mice.

PubMed

Gagnon, Patricia M; Simmons, Dwayne D; Bao, Jianxin; Lei, Debin; Ortmann, Amanda J; Ohlemiller, Kevin K

2007-04-01

The protective benefits of hypoxic preconditioning (HPC) against permanent noise-induced hearing loss (NIHL) were investigated in mice. Hypoxia induced by exposure to 8% O2 for 4 h conferred significant protection against damaging broadband noise delivered 24-48 h later in male and female CBA/J (CBA) and CBA/CaJ mice. No protection was found in C57BL/6 (B6) mice, their B6.CAST-Cdh23(CAST) (B6.CAST) congenics, or in CBAxB6 F1 hybrid mice over the same interval, suggesting that the potential for HPC depends on one or a few autosomal recessive alleles carried by CBA-related strains, and is not influenced by the Cdh23 locus. Protection against NIHL in CBA mice was associated with significant up-regulation of hypoxia-inducible factor-1alpha (HIF-1alpha) within the organ of Corti, not found in B6.CAST. In both CBA and B6.CAST mice, some hypoxia-noise intervals shorter than 24 h were associated with exacerbation of NIHL. Cellular cascades underlying the early exacerbation of NIHL by hypoxia are therefore common to both strains, and not mechanistically linked to later protection. Elucidation of the events that underlie HPC, and how these are impacted by genetics, may lead to pharmacologic approaches to mimic HPC, and may help identify individuals with elevated risk of NIHL.

Fourier domain preconditioned conjugate gradient algorithm for atmospheric tomography.

PubMed

Yang, Qiang; Vogel, Curtis R; Ellerbroek, Brent L

2006-07-20

By 'atmospheric tomography' we mean the estimation of a layered atmospheric turbulence profile from measurements of the pupil-plane phase (or phase gradients) corresponding to several different guide star directions. We introduce what we believe to be a new Fourier domain preconditioned conjugate gradient (FD-PCG) algorithm for atmospheric tomography, and we compare its performance against an existing multigrid preconditioned conjugate gradient (MG-PCG) approach. Numerical results indicate that on conventional serial computers, FD-PCG is as accurate and robust as MG-PCG, but it is from one to two orders of magnitude faster for atmospheric tomography on 30 m class telescopes. Simulations are carried out for both natural guide stars and for a combination of finite-altitude laser guide stars and natural guide stars to resolve tip-tilt uncertainty.

Low-Rank Correction Methods for Algebraic Domain Decomposition Preconditioners

DOE PAGES

Li, Ruipeng; Saad, Yousef

2017-08-01

This study presents a parallel preconditioning method for distributed sparse linear systems, based on an approximate inverse of the original matrix, that adopts a general framework of distributed sparse matrices and exploits domain decomposition (DD) and low-rank corrections. The DD approach decouples the matrix and, once inverted, a low-rank approximation is applied by exploiting the Sherman--Morrison--Woodbury formula, which yields two variants of the preconditioning methods. The low-rank expansion is computed by the Lanczos procedure with reorthogonalizations. Numerical experiments indicate that, when combined with Krylov subspace accelerators, this preconditioner can be efficient and robust for solving symmetric sparse linear systems. Comparisonsmore » with pARMS, a DD-based parallel incomplete LU (ILU) preconditioning method, are presented for solving Poisson's equation and linear elasticity problems.« less

Finding Chemical Reaction Paths with a Multilevel Preconditioning Protocol

DOE PAGES

Kale, Seyit; Sode, Olaseni; Weare, Jonathan; ...

2014-11-07

Finding transition paths for chemical reactions can be computationally costly owing to the level of quantum-chemical theory needed for accuracy. Here, we show that a multilevel preconditioning scheme that was recently introduced (Tempkin et al. J. Chem. Phys. 2014, 140, 184114) can be used to accelerate quantum-chemical string calculations. We demonstrate the method by finding minimum-energy paths for two well-characterized reactions: tautomerization of malonaldehyde and Claissen rearrangement of chorismate to prephanate. For these reactions, we show that preconditioning density functional theory (DFT) with a semiempirical method reduces the computational cost for reaching a converged path that is an optimum undermore » DFT by several fold. In conclusion, the approach also shows promise for free energy calculations when thermal noise can be controlled.« less

Shape reanalysis and sensitivities utilizing preconditioned iterative boundary solvers

NASA Technical Reports Server (NTRS)

Guru Prasad, K.; Kane, J. H.

1992-01-01

The computational advantages associated with the utilization of preconditined iterative equation solvers are quantified for the reanalysis of perturbed shapes using continuum structural boundary element analysis (BEA). Both single- and multi-zone three-dimensional problems are examined. Significant reductions in computer time are obtained by making use of previously computed solution vectors and preconditioners in subsequent analyses. The effectiveness of this technique is demonstrated for the computation of shape response sensitivities required in shape optimization. Computer times and accuracies achieved using the preconditioned iterative solvers are compared with those obtained via direct solvers and implicit differentiation of the boundary integral equations. It is concluded that this approach employing preconditioned iterative equation solvers in reanalysis and sensitivity analysis can be competitive with if not superior to those involving direct solvers.

Preconditioning of the background error covariance matrix in data assimilation for the Caspian Sea

NASA Astrophysics Data System (ADS)

Arcucci, Rossella; D'Amore, Luisa; Toumi, Ralf

2017-06-01

Data Assimilation (DA) is an uncertainty quantification technique used for improving numerical forecasted results by incorporating observed data into prediction models. As a crucial point into DA models is the ill conditioning of the covariance matrices involved, it is mandatory to introduce, in a DA software, preconditioning methods. Here we present first studies concerning the introduction of two different preconditioning methods in a DA software we are developing (we named S3DVAR) which implements a Scalable Three Dimensional Variational Data Assimilation model for assimilating sea surface temperature (SST) values collected into the Caspian Sea by using the Regional Ocean Modeling System (ROMS) with observations provided by the Group of High resolution sea surface temperature (GHRSST). We also present the algorithmic strategies we employ.

Mesenchymal Stem/Stromal Cells in Regenerative Medicine: Can Preconditioning Strategies Improve Therapeutic Efficacy?

PubMed Central

Schäfer, Richard; Spohn, Gabriele; Baer, Patrick C.

2016-01-01

Mesenchymal stem/stromal cells (MSCs) are becoming increasingly important for the development of cell therapeutics in regenerative medicine. Featuring immunomodulatory potential as well as secreting a variety of trophic factors, MSCs showed remarkable therapeutic effects in numerous preclinical disease models. However, sustainable translation of MSC therapies to the clinic is hampered by heterogeneity of MSCs and non-standardized in vitro culture technologies. Moreover, potent MSC therapeutics require MSCs with maximum regenerative capacity. There is growing evidence that in vitro preconditioning strategies of MSCs can optimize their therapeutic potential. In the following we will discuss achievements and challenges of the development of MSC therapies in regenerative medicine highlighting specific in vitro preconditioning strategies prior to cell transplantation to increase their therapeutic efficacy. PMID:27721701

Low-Rank Correction Methods for Algebraic Domain Decomposition Preconditioners

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

Li, Ruipeng; Saad, Yousef

This study presents a parallel preconditioning method for distributed sparse linear systems, based on an approximate inverse of the original matrix, that adopts a general framework of distributed sparse matrices and exploits domain decomposition (DD) and low-rank corrections. The DD approach decouples the matrix and, once inverted, a low-rank approximation is applied by exploiting the Sherman--Morrison--Woodbury formula, which yields two variants of the preconditioning methods. The low-rank expansion is computed by the Lanczos procedure with reorthogonalizations. Numerical experiments indicate that, when combined with Krylov subspace accelerators, this preconditioner can be efficient and robust for solving symmetric sparse linear systems. Comparisonsmore » with pARMS, a DD-based parallel incomplete LU (ILU) preconditioning method, are presented for solving Poisson's equation and linear elasticity problems.« less