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Transient global cerebral ischemia-reperfusion injury can occur during acute severe hypotensive states and in cardiac arrest that is followed by resuscitation. This transient reduction in perfusion causes an insult to selective hippocampal neuronal populations via an apoptotic mechanism. Hydrogen gas has a neuroprotective effect and could be used as a pharmacologic agent of beneficial effect. As such we set out in this study to describe the effect of the inhalation of 2.9% hydrogen enriched air following an ischemia-reperfusion injury. A 2-vessel occlusion model was used to induce global cerebral ischemia for 6 minutes while maintaining a hypotensive state with a mean arterial pressure of 30 mm Hg through reversible exsanguinations in male Sprague-Dawley rats (280–330 g). The study included three groups: global ischemia without treatment (GI, n=6), global ischemia with hydrogen (GI + H2, n=6 ) and sham surgery (Sham, n=6). Rats in the treatment group received 2.9% inhalational hydrogen for 1 hour starting 15 minutes following reperfusion. Neurobehavioral testing was performed on day one and T-maze testing prior to being euthanized on days 3 or 7. Treated rats demonstrated an improved outcomes in spontaneous alternations, seizure incidence and survivability. Quantitative Nissl histology and TUNEL of the CA-1 region of the hippocampus showed increased cell survival in the treatment group. We conclude that treatment with inhalational hydrogen following ischemia-reperfusion injury could be low cost method of decreasing the effects of neuronal cell death.
Liver ischaemia and reperfusion (IR) injury is a significant clinical problem. The aim of our study was to investigate the protective effect of tumor necrosis factor-alpha (TNF-) on rat liver ischaemia-reperfusion injury. A TNF- dose of 3 µg/kg body weight was injected into rats that had undergone partial (70%) ischaemia and reperfusion. The activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), total blood antioxidant level (using the FRAP test), and the concentrations of TNF-, myeloperoxidase (MPO) and malondialdehyde (MDA) in liver homogenates after 1, 6, and 72 hours of reperfusion were measured. It was demonstrated that, rats subjected to IR, the administration of small doses of TNF- significantly reduced ALT and AST activities after 60- minute liver ischaemia and 1 or 6 hour of reperfusion. The strongest reductions in ALT and AST activities were seen after 1 hour of reperfusion (30% and 35%, respectively). Exogenous TNF- reduced the release of this cytokine in all observed periods, with the greatest reduction observed after 1 hour of reperfusion. Decreases in MPO concentration (by 40-45% in all periods of observation), as a marker of hepatic neutrophil infiltration, and in MDA concentration, the end-product of lipid peroxidation (by 55-60% at all time points), accompanied the reduction of TNF- release. The administration of TNF- to the rats after IR did not alter total plasma antioxidant potential, as assayed by the FRAP test, after 1 hour of reperfusion; however, at the later times a marked increase (~ 40-50%) occurred. We demonstrated that intraperitoneal injections of small doses of TNF- protect rat livers from IR injury. The mechanism of this protection is related to reductions in the release of TNF- during IR after injection of this cytokine, resulting in reductions in oxidative stress and inflammation during the later phase of reperfusion.
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Emerging roles of proteasomes in ischemia-reperfusion injury of organs

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Proteasomes are the main non-lysosomal, multicatalytic proteinase complexes involved in the degradation of most intracellular proteins and in numerous cell processes. Studies from isolated cell models indicate that agents that induce oxidative stress may also damage proteasomes. Similarly, continuous oxidative stress during cell aging may impair proteasome activity. In ischemia-reperfusion models of organ injury, proteasomes may be involved in several ways. First, proteasomes were found to be targets of ischemia-reperfusion injury of the brain and heart. Second, proteasome activity increased in liver models of ischemia-reperfusion. Third, proteasome inhibition prevented ischemia-reperfusion injury of the brain, heart and kidney. A major mechanism by which proteasome inhibititors may confer tissue protection is inactivation of transcription activator nuclear factor-B resulting in a block of expression of cytokines and cell adhesion molecules during the reperfusion phase. Thus, proteasome inhibition represents a novel strategy for the treatment of pathologies such as stroke, infarction, and kidney failure.
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