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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The heat shock protein 70 (HSP-70) mRNA level was evaluated in Long Evans rat retinas after ischemia and after reperfusion following ischemia. Retinal ischemia was induced by ligation of the optic nerve and vessels. Rats were sacrificed after 90 min of ischemia or 120 min of reperfusion following ischemia. Retinas were dissected. Total mRNA was extracted and inducible HSP-70 (iHSP-70) gene expression was analyzed by quantification of transcripts using an RT-PCR assay. Results were expressed in arbitrary units as a ratio of the optical density of iHSP-70/beta-actin electrophoretic bands. iHSP-70 gene expression was 0.220 +/- 0.027 (n = 5), 0.502 +/- 0.045 (n = 5) and 0.468 +/- 0.032 (n = 5) for the sham-operated, ischemia only and ischemia and reperfusion groups, respectively. There was a statistically significant difference between the control and ischemia groups, and between the control and ischemia and reperfusion groups (p < 0.001), suggesting a rapid HSP-70 mRNA expression of the retina due to an ischemic injury.
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PMID:Changes of the inducible heat shock protein 70 mRNA level in rat retina after ischemia and reperfusion. 970 32

Heat stress pretreatment of the heart is known to protect this organ against an ischemic/reperfusion insult 24 h later. Degradation of membrane phospholipids resulting in tissue accumulation of polyunsaturated fatty acids, such as arachidonic acid, is thought to play an important role in the multifactorial process of ischemia/reperfusion-induced damage. The present study was conducted to test the hypothesis that heat stress mitigates the postischemic accumulation of arachidonic acid in myocardial tissue, as a sign of enhanced membrane phospholipid degradation. The experiments were performed on hearts isolated from rats either 24 h after total body heat treatment (42 degrees C for 15 min) or 24 h after sham treatment (control). Hearts were made ischemic for 45 min and reperfused for another 45 min. Heat pretreatment resulted in a significant improvement of postischemic hemodynamic performance of the isolated rat hearts. The release of creatine kinase was reduced from 30 +/- 14 (control group) to 17 +/- 5 units/g wet wt per 45 min (heat-pretreated group) (p < or = 0.05). Moreover, the tissue content of the inducible heat stress protein HSP70 was found to be increased 3-fold 24 h after heat treatment. Preischemic tissue levels of arachidonic acid did not differ between heat-pretreated and control hearts. The postischemic ventricular content of arachidonic acid was found to be significantly reduced in heat-pretreated hearts compared to sham-treated controls (6.6 +/- 3.3. vs. 17.8 +/- 12.0 nmol/g wet wt). The findings suggest that mitigation of membrane phospholipid degradation is a potential mechanism of heat stress-mediated protection against the deleterious effects of ischemia and reperfusion on cardiac cells.
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PMID:Heat stress pretreatment mitigates postischemic arachidonic acid accumulation in rat heart. 974 28

Gene expression studies with in situ hybridization after focal brain ischemia indicate a variety of distinct anatomical patterns. An important question is to what extent such reactive gene expression correlates with neuronal damage or survival. To study these questions, we focused on two stressed-induced genes, heat shock protein 70 (HSP70) and growth-arrest and DNA damage-inducible gene (GADD) 45 mRNA, and we compared reactive changes in mRNA to loss of the constitutive signal for microtubule-associated protein 2 (MAP2) mRNA. A pixel-based image analysis of mRNA signals was carried out using a highly reproducible model of focal brain ischemia. A poly-l-lysine coated filament was used to occlude the origin of the middle cerebral artery (MCA) for 2 h in ventilated, normothermic rats. Brains were collected after 0, 1, 3 and 6 h, and 1, 3 and 7 days. In situ hybridization analysis was carried out for HSP70 mRNA, GADD45 mRNA and MAP2 mRNA. Autoradiographic data sets were averaged and co-mapped into a common template of the rat brain. These data sets were then compared on a pixel-by-pixel basis with previously acquired image data sets derived from quantitative studies of local cerebral blood flow (LCBF) (obtained at the end of 2-h ischemia) of and infarctive histopathology (obtained at 3 days) in the same focal ischemia model. HSP70 mRNA and GADD45 mRNA were grossly elevated in the hemisphere subjected to ischemia during the first day. Pixel-based analysis showed a strong correlation between HSP70 mRNA signals, the degree of early blood-flow reduction and the probability of histological infarction. GADD45 mRNA was expressed in a more variable fashion. Decreases in MAP2 mRNA signals at 1, 3 and 7 days correlated strongly with histological infarction. These co-mapping procedures allow us to conclude that HSP70 mRNA is a robust indicator of ischemic stress and histological outcome after 2 h of focal brain ischemia. The topographic features of GADD45 expression suggest its possible role in conferring resistance to ischemic injury. Finally, our results indicate that local decreases in constitutive MAP2 expression at 1 day and beyond may be used as a robust marker of tissue regions having a high probability of focal infarction.
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PMID:Pixel-based image analysis of HSP70, GADD45 and MAP2 mRNA expression after focal cerebral ischemia: hemodynamic and histological correlates. 983 56

Heat shock proteins are intracellular proteins associated with a generalized response of cells to stress. The purpose of this study was to assess RNA levels of heat shock protein 70 and 90 in fed or fasted rat livers during ischemia-reperfusion. Northern blot analysis of heat shock proteins was performed. Adenosine triphosphate and glutathione were assessed. In baseline conditions, livers of fasted rats showed a twofold increase in mRNA for both heat shock proteins and 38% and 43% reductions in adenosine triphosphate and glutathione, respectively, when compared with organs from fed rats. After ischemia, livers of fasted rats presented a twofold decrease in heat shock protein mRNA, while no changes were observed in livers of fed rats; reduced glutathione and adenosine triphosphate decreased 55% and 50% in fasted livers and 25% and 20% in fed organs, respectively. After 120 min of reperfusion, heat shock protein mRNA rose threefold in fasted livers, while a slight decrease was observed in the fed group; reduced glutathione and adenosine triphosphate returned to 65% and 70% of baseline values in fasted livers and 85% and 90% in fed organs, respectively. In conclusion, the nutritional status affects heat shock protein expression determined by reperfusion. The reduced antioxidant status leading to increased oxidative stress could be the mechanism underlying the phenomenon.
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PMID:Effect of ischemia--reperfusion on heat shock protein 70 and 90 gene expression in rat liver: relation to nutritional status. 988 88

The neuroprotective role of the expression of heat shock protein (HSP) and immediate early gene remains unclear. Using immunoelectron microscopy, we examined the ultrastructural integrity of the neurons with expression of c-Fos, c-Jun and HSP70 in gerbils after transient cerebral ischemia and reperfusion. Induction of c-Fos and c-Jun was observed in the CA3 region resistant to ischemia, while HSP70 was expressed not only in the CA3 but also in the vulnerable CAI region. With immunoelectron microscopy, the expression of c-Fos/c-Jun and HSP70 was observed in the neurons which retained neuronal integrity except for mitochondrial swelling and polyribosomal disaggregation. In contrast, the CAI neurons without immunoreaction for HSP70 showed cytoplasmic vacuoles and parallel stacking of rough endoplasmic reticulum, the features associated with the process of delayed neuronal death. These findings suggested that c-Fos and c-Jun were induced selectively in reversibly damaged neurons, whereas HSP70 was up-regulated even in neurons with irreversible damage, but was more preferentially and intensely expressed in neurons with reversible damage.
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PMID:Immunoelectron microscopic study of c-Fos, c-Jun and heat shock protein after transient cerebral ischemia in gerbils. 993 Aug 91

To identify genes induced by transient forebrain ischemia, we used the mRNA differential display technique in the four-vessel occlusion model in rats. Some genes were identified as candidates that encode ischemia-responsive protein, and one of them was cloned as ischemia-responsive protein 94 kDa (irp94) from the rat hippocampal cDNA library. Sequence analysis suggested that rat irp94 was a transcriptional variant or a homologue of mouse apg-2 and human heat shock protein (hsp) 70RY and a member of the HSP110 family, because IRP94 was >90% identical to APG-2 and HSP70RY and approximately 60% identical to the other members of the HSP110 family. Although irp94 mRNA was constitutively expressed in the normal hippocampus, it was clearly enhanced 4-24 h after ischemia for 10 (1.9-fold increase) and 15 min (3.4-fold increase). These changes mainly occurred in neuronal cells, as judged by the localization of irp94 mRNA using in situ hybridization histochemistry. On the other hand, hyperthermic stress did not enhance irp94 mRNA expression, suggesting that irp94 expression was enhanced under ischemic stress and not related to the heat shock signaling mechanism. Our study suggested that irp94, a novel member of the HSP110 family, might play an important role in the environment altering neuronal functions, especially after transient forebrain ischemia.
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PMID:Molecular cloning of a novel member of the HSP110 family of genes, ischemia-responsive protein 94 kDa (irp94), expressed in rat brain after transient forebrain ischemia. 1009 60

In the course of adaptation to exercise, enhanced resistance of isolated heart against ischemia and reperfusion correlated with accumulation of cytoprotective proteins of the HSP70 family and increased potency of sarcoplasmic reticulum (SR) Ca2+ pump in the rat myocardium. Blockade of the HSP70 synthesis with guercetin prevented development of protection of the heart against ischemia and reperfusion. In the course of the adaptation, the increased resistance of the Ca2+ pump against detrimental factors preceded its potentiation. The findings suggest that the HSP70 accumulation and increased potency and resistance of the SR Ca2+ transport system in the myocardium are important mechanisms of adaptive protection of the heart.
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PMID:[The role of HSP70 and Ca(2+)-pump from the myocardial sarcoplasmic reticulum in cardioprotective effects during adaptation to physical load in rats]. 1020 65

Heat shock proteins present a complex family of proteins exerting chaperone-like activities that are classified according to their molecular weight. We especially explored protective functions of inducible heat shock protein 70, the mitochondrial heat shock protein 60 and 10, and the small heat shock proteins HSP27 and alphaB-crystallin against ischemic, reoxygenation-mediated injury using transgenic animals and hearts under in vivo conditions and in isolated cardiac myocyte-derived cells using adenoviral vectors. We noted with great interest that differential protective effects are exerted by specific hsps. For example, alpha-B-crystallin and constitutive hsp70 markedly protect microtubular structure in cardiac myocytes from ischemia-induced injury. Inducible hsp70, hsp60 and hsp10 when coexpressed, and hsp27 and alphaB-crystallin have an overall protective effect against ischemic injury as determined by the release of enzymes like creatine kinase and LDH. We did not note inflammatory or immune responses elicited by the expression of hsps in transgenic animals and cardiac myocytes. The specific cell types in which hsps are expressed may contribute to the protective effect of hsps versus their inflammatory and immunogenic effects when expressed in other cell types.
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PMID:Heat shock proteins and protection against ischemic injury. 1023 Oct 10

Hypothermia improves resistance to subsequent ischemia in the cardioplegic-arrested heart (CAH). This adaptive process produces mRNA elevation for heat shock protein (HSP) 70-1 and mitochondrial proteins, adenine nucleotide translocator (ANT(1)), and beta-F(1)-ATPase. Glucose in cardioplegia also enhances myocardial protection. These processes might be linked to reduced ATP depletion. To assess for synergism between these protective processes, isolated rabbit hearts (n = 91) were perfused at 37 degrees C and exposed to ischemic cardioplegic arrest for 2 h. Hearts were in four groups: control (C), hypothermia adapted (H) perfused to 31 degrees C 20 min before ischemia, 22 mM glucose (G) in cardioplegia, and hypothermic adaptation and glucose (HG). Developed pressure (DP), dP/dt(max), and pressure-rate product (PRP) improved (P < 0.05) in G, H, and HG compared with C during reperfusion. DP and PRP were elevated in HG over H and G. ATP was higher in G, H, and HG, although no additional increase in HG over H was found. Lactate and CO(2) production were elevated in G only. The mRNA expression for HSP70-1, ANT(1), and beta-F(1)-ATPase was elevated severalfold in H and HG, but not G over C during reperfusion. In conclusion, glucose provides additional functional improvement in H. Additionally, neither ATP levels nor anaerobic metabolism are linked to mRNA expression for HSP70, ANT(1), or beta-F(1)-ATPase in CAH.
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PMID:Mitochondrial protein and HSP70 signaling after ischemia in hypothermic-adapted hearts augmented with glucose. 1040 52

The small heat shock proteins alpha B crystallin and HSP27 exert a protective effect in response to simulated ischemia. A model is proposed whereby proteins not in their final folding state bind to the outside of the large oligomeric small heat shock protein complexes thus finding a safe haven during ischemia. After the ischemia is resolved, these proteins may be released and, with the help of HSP70, are shuttled to a productive refolding pathway resulting in proteins in their final folding state, which can assume their normal activity in cells recovered from ischemic injury.
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PMID:Small heat shock proteins and protection against injury. 1041 21


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