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

Transient ischemia-induced perturbations in calcium homeostasis have been proposed to lead to pathological activation of the cysteine protease calpain I and subsequent delayed neuronal death in the CA1 region of hippocampus. We report here on the design and characterization of antibodies selective for calpain-generated fragments of brain spectrin, and their use for immunoblot and immunohistochemical analyses of calpain activation following cerebral ischemia in the gerbil. Although spectrin was susceptible to degradation in vitro by many mammalian proteases, only calpain degraded spectrin to generate fragments immunoreactive with the antibodies. Following 5 min of global ischemia, immunoreactivity for calpain-degraded spectrin was rapidly (within 30 min) and markedly elevated in the perikarya and dendrites of several populations of forebrain neurons. The rapid calpain activation was completely prevented by the NMDA receptor antagonist MK-801. At later times postischemia, but prior to frank neuronal necrosis, calpain-degraded spectrin was restricted to hippocampal area CA1 pyramidal neurons. Silver impregnation histochemistry confirmed that neuronal damage was confined to area CA1. The results indicate that while nonpathological NMDA receptor stimulation can activate calpain, only those neurons showing sustained calpain activation are destined to die.
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PMID:Immunolocalization of calpain I-mediated spectrin degradation to vulnerable neurons in the ischemic gerbil brain. 820 97

Cystatin C, a cysteine protease inhibitor produced by the choroid plexus and found in CSF at high concentrations, may have an important role in brain injury. We used the two-vessel occlusion model with hypotension to induce transient forebrain ischemia (TFI) in rats for 10 min and then examined cystatin C immuno-like reactivity (CC-IR) after 1, 3, 7 and 14 days of recovery. Our results reveal that CC-IR was minimal or absent in the hippocampus of normal and 1 day post-ischemic animals. However, CC-IR was present in CA1 pyramidal cells and a small number of reactive glia of the stratum radiatum (SR) and stratum oriens (SO) at 3, 7 and 14 days post-ischemia. Histological assessment of the hippocampus indicates that CC-IR was localized in morphologically degenerative neurons. This distinct temporal expression of cystatin C in the rat hippocampus is concurrent with delayed neuronal death following TFI. Thus, these results indicate that cystatin C and/or its substrates may be important components of the post-ischemic neurodegenerative and repair process.
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PMID:Cystatin C, a protease inhibitor, in degenerating rat hippocampal neurons following transient forebrain ischemia. 859 41

To understand better the pathophysiology of random skin flaps, randomized skin flaps of human (3 cases) and guinea pig (53 cases) were investigated. Proximal (normal), proximomedial (viable), mediodistal (between viable and necrotic parts), and distal (necrosis) locations of the skin flaps were biopsied. Lipid peroxidase, hydrolytic enzymes of cytosol (Ca(2+)-dependent cysteine protease: calpain), and lysosome (acid phosphatase) of skin were used as markers. Measurements were taken of the flap blood flow; the numbers of capillaries, postcapillary venules, pericapillary arterioles, leukocytes, and mast cells per unit square of dermis. Apoptotic cells were identified by specific staining. Flaps were sampled at postoperative weeks 1 and 3 (human) and hours 1 and 6, and days 1 to 7 (guinea pig). The values for normal skin were regarded as the control. Obstruction (by leukocytes) of venous microvessels, rather than arterial microvessels, was the major cause of temporary hypoxia in the proximomedial location, constant hypoxia (venous stasis) in the mediodistal location, and ischemia in the distal location. Increases in the number of mast cells (mastocytosis) and microvessels (angiogenesis) were significant only in the viable parts of the flaps. This phenomenon and the rate of blood flow increased with time in viable locations (guinea pig). Epidermal necrosis, dermal fibrosis, and apoptosis were evident mostly in the mediodistal location. Elevated levels of leukocytes, lipid peroxidase, acid phosphatase, and calpain, combined with necrotic changes, were seen mostly in the distal skin location. There is a strong possibility that the following factors are involved: lipid piroxidation and hydrolysis in necrosis of the distal flap location after ischemia; constant hypoxia in fibrosis and apoptosis in the mediodistal location; and initial or temporary hypoxia in mastocytosis-induced angiogenesis in the viable location. The results presented here indicate that guidelines for further investigations include combined suppression of leukotaxis, lipid peroxidase, and hydrolysis, or the application of mast cell growth factors in an effort to salvage the flap maximally.
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PMID:Possible contributions of mastocytosis, apoptosis, and hydrolysis in pathophysiology of randomized skin flaps in humans and guinea pigs. 870 Sep 87

The interleukin 1beta converting enzyme (ICE) family plays a pivotal role in programmed cell death and has been implicated in stroke and neurodegenerative diseases. During reperfusion after filamentous middle cerebral artery occlusion, ICE-like cleavage products and tissue immunoreactive interleukin 1beta (IL-1beta) levels increased in ischemic mouse brain. Ischemic injury decreased after intracerebroventricular injections of ICE-like protease inhibitors, N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (z-VAD.FMK), acetyl-Tyr-Val-Ala-Asp-chloromethylketone, or a relatively selective inhibitor of CPP32-like caspases, N-benzyloxycarbonyl-Asp-Glu-Val-Asp-fluoromethylketone, but not a cathepsin B inhibitor, N-benzyloxycarbonyl-Phe-Ala-fluoromethylketone. z-VAD.FMK decreased ICE-like cleavage products and tissue immunoreactive IL-1beta levels in ischemic mouse brain and reduced tissue damage when administered to rats as well. Only z-VAD.FMK and acetyl-Tyr-Val-Ala-Asp-chloromethylketone reduced brain swelling, and N-benzyloxycarbonyl-Asp-Glu-Val-Asp-fluoromethylketone did not attenuate the ischemia-induced increase in tissue IL-1beta levels. The three cysteine protease inhibitors significantly improved behavioral deficits, thereby showing that functional recovery of ischemic neuronal tissue can follow blockade of enzymes associated with apoptotic cell death. Finally, we examined the effect of z-VAD.FMK on excitotoxicity and found that it protected against alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate-induced or to a lesser extent N-methyl-D-aspartate-induced excitotoxic brain damage. Thus, ICE-like and CPP32-like caspases contribute to mechanisms of cell death in ischemic and excitotoxic brain injury and provide therapeutic targets for stroke and neurodegenerative brain damage.
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PMID:Inhibition of interleukin 1beta converting enzyme family proteases reduces ischemic and excitotoxic neuronal damage. 905 Aug 95

The objective of this study was to examine the possible role of the cysteine protease cathepsin B (E.C. 3.4.22.1) in the delayed neuronal death in rats subjected to the two-vessel occlusion model of global ischemia. Immunohistochemistry of the hippocampus showed an alteration in the distribution of cathepsin B in CA1 neurons from a lysosomal pattern to a more intense label redistributed into the cytoplasm. This change was not detected until the neurons had become morphologically altered with obvious shrinkage of the cytoplasmic region. Western blotting and enzyme activity measurements of subcellular fractions, including lysosomes and a cell soluble fraction, demonstrated that there was an overall decrease in cathepsin B activity at this time but an increase in the proenzyme form, particularly in the soluble fraction. This was found to be completely different from the marked loss of all forms of cathepsin B in necrotic neurons following decapitation.
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PMID:A comparison of cathepsin B processing and distribution during neuronal death in rats following global ischemia or decapitation necrosis. 909 7

Lysosomal proteases, although tightly regulated under physiological conditions, are known to contribute to cell injury after various forms of tissue ischemia have occurred. Because cathepsin B is a prominent lysosomal protease found in brain parenchyma, the authors hypothesized that it may contribute to neuronal cell death after focal cerebral ischemia. The authors measured the expression and spatial distribution of cathepsin B within the ischemic brain in 43 animals by means of immunohistochemical analysis in a rat model of transient middle cerebral artery (MCA) occlusion. Cathepsin B activity was also measured within specific ischemic brain regions by using an in vitro assay (22 animals). In addition, the authors tested the therapeutic effect of preischemic intraventricular administration of stefin A, a cysteine protease inhibitor, on the volume of cerebral infarction after transient MCA occlusion (15 animals). Increased cathepsin B immunoreactivity was detected exclusively within the ischemic neurons after 2 hours of reperfusion following a 2-hour MCA occlusion. Cathepsin B immunolocalization in the ischemic region decreased by 24 hours of reperfusion, but then increased by 48 hours of reperfusion because the infarct was infiltrated by inflammatory cells. Increased immunolocalization of cathepsin B in the inflammatory cells located in the necrotic infarct core continued through 7 days of reperfusion. Cathepsin B enzymatic activity was significantly increased in the ischemic tissue at 2, 8, and 48 hours, but not at 24 hours of reperfusion after 2 hours of MCA occlusion. Continuous intraventricular infusion of stefin A, before 2 hours of MCA occlusion (15 animals), significantly reduced infarct volume compared with control animals (12 animals): the percentage of hemispheric infarct volume was 20+/-3.9 compared with 33+/-3.5 (standard error of the mean; p = 0.025). These data indicate that neuronal cathepsin B undergoes increased expression and activation within 2 hours of reperfusion after a 2-hour MCA occlusion and may be a mechanism contributing to neuronal cell death. Intraventricular infusion of stefin A, an inhibitor of cathepsin B, significantly reduces cerebral infarct volume in rats.
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PMID:Cathepsin B and middle cerebral artery occlusion in the rat. 934 80

The authors recently cloned a cDNA for an ICE/CED3-related cysteine protease from rat brain, which is closely related to human CPP32 (now designated caspase-3). In situ hybridization histochemistry revealed a profound developmental regulation of the caspase-3 transcript in rat brain, with relatively high levels of caspase-3 mRNA observed in neurons of the fetal and neonatal brain and low levels of mRNA in neurons of the adult brain. The authors report that transient forebrain ischemia, which results in a delayed apoptotic death of CA1 pyramidal neurons, results in prolonged expression of caspase-3 mRNA in these same pyramidal neurons. Up-regulation of caspase-3 mRNA in CA1 pyramidal neurons is prominent 24 hours after transient global ischemia, and expression is maintained at higher levels for at least 72 hours after ischemia. However, by 96 hours after ischemia, a marked decrease in caspase-3 mRNA expression is observed in CA1 pyramidal neurons, showing severe degenerative changes (e.g., nuclear condensation). By contrast, there is no change in the expression of a closely related member of caspase family, caspase-2, in CA1 pyramidal neurons after global ischemia. Instead, caspase-2 mRNA is induced in lamina layers of cerebral cortex 24 hours after the ischemia. A selective and prolonged induction of the caspase-3 gene in committed CA1 pyramidal neurons suggests that transcriptional activation of this caspase-3 gene may be involved in the apoptotic cell death cascade of CA1 neurons after transient global ischemia.
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PMID:Transient global forebrain ischemia induces a prolonged expression of the caspase-3 mRNA in rat hippocampal CA1 pyramidal neurons. 949 41

Delayed neuronal death after transient cerebral ischemia may be mediated, in part, by the induction of apoptosis-regulatory gene products. Caspase-3 is a newly characterized mammalian cysteine protease that promotes cell death during brain development, in neuronal cultures, and in other cell types under many different conditions. To determine whether caspase-3 serves to regulate neuronal death after cerebral ischemia, we have (1) cloned a cDNA encoding the rat brain caspase-3; (2) examined caspase-3 mRNA and protein expression in the brain using in situ hybridization, Northern and Western blot analyses, and double-labeled immunohistochemistry; (3) determined caspase-3-like activity in brain cell extracts; and (4) studied the effect of caspase-3 inhibition on cell survival and DNA fragmentation in the hippocampus in a rat model of transient global ischemia. At 8-72 hr after ischemia, caspase-3 mRNA and protein were induced in the hippocampus and caudate-putamen (CPu), accompanied by increased caspase-3-like protease activity. In the hippocampus, caspase-3 mRNA and protein were predominantly increased in degenerating CA1 pyramidal neurons. Proteolytic activation of the caspase-3 precursor was detected in hippocampus and CPu but not in cortex at 4-72 hr after ischemia. Double-label experiments detected DNA fragmentation in the majority of CA1 neurons and selective CPu neurons that overexpressed caspase-3. Furthermore, ventricular infusion of Z-DEVD-FMK, a caspase-3 inhibitor, decreased caspase-3 activity in the hippocampus and significantly reduced cell death and DNA fragmentation in the CA1 sector up to 7 d after ischemia. These data strongly suggest that caspase-3 activity contributes to delayed neuronal death after transient ischemia.
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PMID:Induction of caspase-3-like protease may mediate delayed neuronal death in the hippocampus after transient cerebral ischemia. 963 57

The newly-developed calpain inhibitor, MDL 28170 penetrates the blood-brain barrier and inhibits brain cysteine protease activity after systemic administration. This experiment was initiated to determine if the calpain inhibitor, MDL 28170 could, by these actions, reduce neuronal damage in an animal model of global cerebral ischemia in the gerbil. The calpain inhibitor, MDL 28170 (50 mg/kg), was initiated at 0.5 and 3 h of recirculation following 5min of global ischemia. Animals subjected to ischemia but without treatment or with vehicle treatment served as controls. Evaluation by light microscopy was carried out on paraffin-embedded brain sections of gerbils which were sacrificed 7 days post-operatively. The results show that the calpain inhibitor, MDL 28170, protects against cortical neuronal damage even if the treatment is delayed until 3 h after reperfusion. However, the neuroprotective effect of this agent is less pronounced in the hippocampal CA1 sector. The results suggest that calpain-mediated proteolysis plays an important role in neuronal death due to ischemia. However, additional mechanisms by which an increased intracellular calcium concentration leads to neuronal death may exist.
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PMID:Postischemic treatment with calpain inhibitor MDL 28170 ameliorates brain damage in a gerbil model of global ischemia. 963 99

Apoptotic cell suicide initiated by ligation of CD95 (Fas/APO-1) occurs through recruitment, oligomerization and autocatalytic activation of the cysteine protease, caspase-8 (MACH, FLICE, Mch5). An endogenous mammalian regulator of this process, named Usurpin, has been identified (aliases for Usurpin include CASH, Casper, CLARP, FLAME-1, FLIP, I-FLICE and MRIT). This protein is ubiquitously expressed and exists as at least three isoforms arising by alternative mRNA splicing. The Usurpin gene is comprised of 13 exons and is clustered within approximately 200 Kb with the caspase-8 and -10 genes on human chromosome 2q33-34. The Usurpin polypeptide has features in common with pro-caspase-8 and -10, including tandem 'death effector domains' on the N-terminus of a large subunit/small subunit caspase-like domain, but it lacks key residues that are necessary for caspase proteolytic activity, including the His and Cys which form the catalytic substrates diad, and residues that stabilize the P1 aspartic acid in substrates. Retro-mutation of these residues to functional caspase counterparts failed to restore proteolytic activity, indicating that other determinants also ensure the absence of catalytic potential. Usurpin heterodimerized with pro-caspase-8 in vitro and precluded pro-caspase-8 recruitment by the FADD/MORT1 adapter protein. Cell death induced by CD95 (Fas/APO-1) ligation was attenuated in cells transfected with Usurpin. In vivo, a Usurpin deficit was found in cardiac infarcts where TUNEL-positive myocytes and active caspase-3 expression were prominent following ischemia/reperfusion injury. In contrast, abundant Usurpin expression (and a caspase-3 deficit) occurred in surrounding unaffected cardiac tissue, suggesting reciprocal regulation of these pro- and anti-apoptotic molecules in vivo. Usurpin thus appears to be an endogenous modulator of apoptosis sensitivity in mammalian cells, including the susceptibility of cardiac myocytes to apoptotic death following ischemia/ reperfusion injury.
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PMID:Cell death attenuation by 'Usurpin', a mammalian DED-caspase homologue that precludes caspase-8 recruitment and activation by the CD-95 (Fas, APO-1) receptor complex. 1020 Apr 73


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