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

An 11-year-old boy with slowly progressive gangrene caused by vasculopathy similar to that of neurofibromatosis (NF) type 1 (NF I; von Recklinghausen disease [NFvR]) and a newborn girl with idiopathic gangrene with vascular changes resembling those of NFvR prompted the analysis of all 105 propositi with NF (NF I and NF II) evaluated between January 2, 1982, and December 31, 1986, at the genetics clinic of University of South Florida. They were analyzed for renal hypertension, symptomatic ischemia, and known vascular changes. One additional 27-month-old boy with NFvR was found to have extensive vascular changes with renal hypertension. The vasculopathy indicated asymmetric over/undergrowth of cellular and extracellular components of the vascular wall and implied dysregulation of the paracrine growth mechanism. Immunocytochemical studies of affected vessels were done only in the 11-year-old boy and showed positive neuron-specific enolase, S-100 protein, and glial fibrillary acidic protein (GFAP) reactions indicative of Schwann cell involvement. The vascular changes in children with NFvR are mostly asymptomatic; however hypertension secondary to renal artery stenosis and/or Moya-moya disease have been reported infrequently. Our patients with vasculopathies provoked thoughts in regard to the so-called vascular NF, its place in current NF nomenclature and classification, relationship to fibromuscular dysplasia (FMD), and possible role in infantile gangrene.
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PMID:"Vascular neurofibromatosis" and infantile gangrene. 251 May 17

Transient global ischemia was produced in rats by cisternal fluid infusion, producing a negative cerebral perfusion pressure by elevating the intracranial pressure (ICP) 25-50 mm Hg above mean arterial pressure (MAP). Animals were allowed to survive for 2-7 days following a transient ischemic episode of 5-30 min. The brains were examined for signs of ischemic degeneration in Nissl-stained sections and adjacent sections reacted with antisera against glial fibrillary acidic protein (GFAP) or aspartate aminotransferase (AAT). Neurons in the thalamic reticular nucleus (RT), a pure population of gamma-aminobutyric acid (GABA)ergic neurons which project their axons to thalamic relay nuclei, were found to have the lowest threshold for degeneration in this model, consistently undergoing degeneration under conditions which completely spared the hippocampal CA1 from degeneration. Whereas it took up to 30 min of complete ischemia to produce degeneration of CA1 neurons when ICP was raised using room temperature infusion fluids, 15 min of ischemia under these conditions was sufficient to produce extensive degeneration of neurons in the entire ventral 3/4 of the RT. Prolonged (greater than 25 min) episodes of partial ischemia (ICP less than or equal to MAP) were also sufficient to produce massive degeneration of RT neurons. The lesion in the RT was most clearly evident in sections reacted with antisera to GFAP, labeling intensely reactive protoplasmic astrocytes within the regions of the RT where neuronal degeneration had occurred. Neuronal loss and accompanying proliferation of microglial cells were evident in Nissl-stained sections but the extent of the neuronal loss was most clearly obvious in sections reacted with an antisera to AAT, an enzyme present in detectable quantities in GABAergic neurons. Pretreatment with the non-competitive NMDA antagonist MK-801 at doses sufficient to completely prevent massive degeneration of the hippocampal CA1 failed to prevent the degeneration of RT neurons, suggesting that if RT degeneration involves an excitotoxic process it acts through non-NMDA receptors.
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PMID:Degeneration of neurons in the thalamic reticular nucleus following transient ischemia due to raised intracranial pressure: excitotoxic degeneration mediated via non-NMDA receptors? 255 11

The effects of ischemia (removal of oxygen and glucose for 4 h) and anoxia (removal of oxygen alone) on astrocytes were studied in dissociated cultures of E14 spinal cord containing both neurons and astrocytes. In addition, a group of cultures was treated with a low Na+, low Ca2+, and high K+ medium during the 4-h ischemic period (ischemia-protected group), a process that protects neurons from ischemic damage under identical conditions. Astrocytes were examined immunohistochemically using glial fibrillary acidic protein (GFAI) antiserum 24 h after insult. Densitometry and statistical analysis (1-way analysis of variance [ANOVA], a priori; 2-tailed Tukey-t, a posteriori) of the digitized images of the somata and processes of astrocytes in the anti-GFAP reacted cultures showed significant differences between the groups; a significant increase (P less than 0.01) in the GFAP-positive reaction in the somata of ischemic astrocytes and a significant decrease (P less than 0.01) in the GFAP-positive reaction in the processes of ischemic, ischemia-protected, and anoxic astrocytes. There were no significant differences in the GFAP immunoreactivity of somata between control, ischemia-protected, and anoxic astrocytes or of processes from ischemic, ischemia-protected, and anoxic astrocytes. These data show that following ischemia cultured astrocytes increase somatic GFAP immunoreactivity compared to all other groups tested whereas the staining intensity for GFAP was decreased in the processes of all three experimental groups compared to controls. Ischemia protection resulted in the absence of the enhancement of somatic GFAP immunoreactivity. The relationship of the astrocytic response and the type of cellular stress is discussed.
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PMID:Glial fibrillary acidic protein immunohistochemistry of spinal cord astrocytes after induction of ischemia or anoxia in culture. 358 70

This study examined the pattern of protein synthesis in the neocortex, caudate-putamen, and the hippocampus following transient forebrain ischemia in rats. The animal model of temporary ischemia used in this study causes permanent damage to vulnerable neurons with a time course of injury that varies from hours (caudate nucleus) to days (hippocampus). To examine the spectrum of proteins synthesized in these regions at 3 and 18 h after recirculation, cerebral proteins were pulse-labeled in vivo by an intravenous injection of [35S]methionine. Newly synthesized (35S-labeled) and constitutive (unlabeled) proteins were analyzed by two-dimensional gel electrophoresis and fluorography. In all three brain regions, specific proteins underwent preferential synthesis (Mr approximately 27,000, approximately 65,000, approximately 70,000, approximately 110,000), while others showed decreased synthesis (neuron-specific enolase, alpha- and beta-tubulin). There was an early (3 h post ischemia) induction of the Mr approximately 70,000 mammalian "stress" protein; at 18 h post ischemia, its synthesis remained high in the hippocampus but was diminished in the neocortex and had largely subsided in the caudate-putamen. All regions at 18 h showed increased synthesis of an Mr approximately 50,000 protein, tentatively identified as glial fibrillary acidic protein. The results show that temporary forebrain ischemia induces changes in protein synthesis that include features similar to those observed in other eukaryotic cells subjected to injurious stress. These postischemic changes in protein synthesis are qualitatively similar in all brain regions examined despite regional differences in the severity of subsequent neuronal damage. The persistent synthesis of the Mr approximately 70,000 stress protein in the hippocampus, however, may reflect continued metabolic injury long after the ischemic episode has passed.
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PMID:Protein synthesis in postischemic rat brain: a two-dimensional electrophoretic analysis. 379 99

We recently demonstrated that reactive astrocytes express NADPH diaphorase activity, a marker for Nitric Oxide Synthase, following transient global ischemia (Neuroscience Letters 154: 125-128). There has been little evidence that astrocytes express Nitric Oxide Synthase or produce NO (nitric oxide) in vivo; although in vitro experiments have shown that cultured astrocytes can produce NO. To determine whether reactive astrocytes express inducible form of NOS (iNOS) in vivo, we studied the pathological changes of rat hippocampus by immunohistochemistry after 10 minutes of transient global ischemia, which results in the selective delayed death of CA1 pyramidal cells and marked gliosis in the CA1 subfield. In the normal hippocampus, astrocytes express neither NADPH diaphorase activity nor iNOS. After ischemia, the temporal and spatial pattern of iNOS, NADPH diaphorase, and GFAP are very similar, indicating that reactive astrocytes express iNOS. Double staining for NADPH diaphorase and GFAP, or iNOS and GFAP confirmed that reactive astrocytes express both NADPH diaphorase activity and iNOS immunoreactivity. These changes were observed three day after ischemia and increased in prominence from one week to one month. The staining pattern of OX42, an antibody that recognizes both microglia and macrophages, is spatially and temporally distinct from the pattern of NADPH diaphorase and iNOS staining. Thus, we conclude that transient global ischemia induces iNOS primarily in reactive astrocytes. This increase in NOS expression and, presumably, NO production by reactive astrocytes may play a role in the process of delayed neuronal death or in the remodeling responses that occur after ischemic damage.
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PMID:Expression of the inducible form of nitric oxide synthase by reactive astrocytes after transient global ischemia. 752 35

Sequential and regional changes in ischemic edema following various durations of focal cerebral ischemia were studied by magnetic resonance (MR) imaging in a rat unilateral intraluminal middle cerebral artery occlusion model. Occlusion was performed from 5 minutes to 5 hours. T2-weighted images were obtained chronologically 6 hours after onset of ischemia, on day 1 and day 7. An immunohistochemical study using antibodies to calcineurin and glial fibrillary acidic protein was performed to observe histological changes in the ischemic brain. The T2 high-signal-intensity areas representing ischemic edema were observed in the lateral striatum and/or the cerebral cortex by day 1 in all rats with 1- to 5-hour ischemia, and the areas were larger and detected earlier with longer durations of ischemia. In three of six rats with 15-minute ischemia and five of six rats with 30-minute ischemia, the T2 high-signal-intensity areas appeared transiently on day 1 in the dorsolateral striatum where loss of neurons expressing calcineurin immunoreactivity and associated gliosis were found. MR imaging in animal models of reversible focal ischemia can achieve sequential and noninvasive evaluation of dynamic regional changes in ischemic edema.
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PMID:Sequential changes in ischemic edema following transient focal cerebral ischemia in rats: magnetic resonance imaging study. 752 28

The postischemic time course of amyloid protein precursor (APP), beta-amyloid protein (beta-AP), and apolipoprotein E (APO-E) immunoreactivity were examined in comparison to neuronal necrosis in the selectively vulnerable hippocampal CA1 region of gerbils subjected to 10 min of bilateral carotid occlusion-induced forebrain ischemia. Loss of 90% of the CA neurons occurred between 24 and 72 h after ischemia, after which no further neuronal necrosis was observed. At 24 h postischemia, there was a decrease in APP and beta-AP immunostaining in the CA1 region. However, beginning at 2 days, there was a dramatic increase in the staining for both proteins. This coincided with a progressive increase in the expression of APO-E and glial fibrillary acidic protein (GFAP) staining between Days 2 and 6, indicative of an activation of astrocytic protein synthesis. Each of the immunocytochemical markers also increased in the less vulnerable CA3 region. However, the peak increase in that region was much less than that in CA1 and, by 7 days, only the GFAP staining remained significantly above the sham level. It has been shown that the E4 isoform of APO-E, when oxidized, avidly binds to beta-AP and thus increases the likelihood of co-beta-AP/APO-E deposition. Therefore, it is postulated that the increased levels of amyloid proteins coincident with an increased production of APO-E in response to ischemic neuronal necrosis may provide conditions that are favorable for the postischemic formation of amyloid deposits.
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PMID:Increased amyloid protein precursor and apolipoprotein E immunoreactivity in the selectively vulnerable hippocampus following transient forebrain ischemia in gerbils. 755 50

We examined by morphological methodology the effect of (S)-N-ethyl-3-[(1-dimethyl-amino)ethyl]-N-methyl-phenylcarbamate hydrogentartrate (ENA-713), an acetylcholinesterase (AChE) inhibitor, on ischemia-induced neuronal death in the gerbil hippocampus due to a 5-min ligation of bilateral common carotid arteries after light ether anesthesia. Pyramidal cells had been decreased to 27% of sham-operated controls and the number of hypertrophic astrocytes expressing glial fibrillary acidic protein (GFAP) markedly increased in the hippocampal CA1 subfield 14 days after ischemia. However, post-ischemic administration of ENA-713 (three times 0.2 mg/kg, i.p.) significantly ameliorated this ischemia-induced decrease in the number of pyramidal cells by 47% of sham-operated controls, furthermore, it reduced the ischemia-induced accumulation of GFAP-positive astrocyte in the CA1 region. Together with previous results showing that ENA-713 protected against the ischemia-induced cholinergic abnormalities in the gerbil brain and improved cholinergic dysfunctions in the senescent rat brain, our present findings suggest that ENA-713 prove to be useful for treatment with senile dementia such as cerebrovascular dementia.
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PMID:Post-ischemic administration of the acetylcholinesterase inhibitor ENA-713 prevents delayed neuronal death in the gerbil hippocampus. 756 61

Involvement of the IEGs in brain injury and ischemia is under intensive investigation (Gubits et al., 1993). There are several families of the IEGs. They include the fos, jun, and zinc finger genes that encode transcription factors. Products of the fos family (c-fos, fra-1, fra-2, and fos B) bind to members of the jun family (c-jun, jun B, jun D) via leucine zippers, and this dimer then binds to the AP-1 site (consensus sequence -TGACTCA-) in the promoter of target genes, which in turn regulate the expression of late response genes that produce long-term changes in cells. For example, c-fos may regulate the long-term expression of preproenkephalin, nerve growth factor, dynorphin, vasoactive intestinal polypeptide, tyrosine hydroxylase and other genes with AP-1 sites in their promoters (Curran and Morgan, 1987; Sheng and Greenberg, 1990). It is likely that the c-fos gene up-regulation observed in ischemic astrocytes leads to the changes observed in the expressions of hsp and cytoskeleton protein genes in this experimental model. This is supported by the findings of Sarid (1991) and Pennypacker et al. (1994) who have shown that AP-1 DNA binding activity in hippocampus recognized an AP-1 sequence from the promoter region of the GFAP which is a potential target gene. van de Klundert et al. (1992) also suggested the involvement of AP-1 in transcriptional regulation of vimentin. IEGs can be induced within minutes by extracellular stimuli including transmitters, peptides, and growth factors. In this study, we have shown that c-fos induction by ischemia was rapid and transient.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Gene expression in astrocytes during and after ischemia. 756 84

In the hippocampus there is a graded vulnerability of neuronal subpopulations to hypoglycemia-induced degeneration, most likely due to excitotoxic activation of glutamate receptors. The present study was conducted to investigate whether the induction of transcription factors of the immediate early gene (IEG) family after hypoglycemia reflects these different grades of neuronal vulnerability. We studied the expression profile of seven IEG-coded proteins in the rat hippocampus following severe insulin-induced hypoglycemia with 30 min of EEG isoelectricity and various survival periods for up to 42 h after glucose replenishment. Immunocytochemistry was performed on vibratome sections with specific polyclonal antisera directed against c-FOS, FOS B, c-JUN, JUN B, JUN D, KROX-24, and KROX-20. To unequivocally define the type of glial cells showing IEG induction, we investigated coexpression of c-FOS and glial marker proteins (glial fibrillary acid protein [GFAP], OX-42) by confocal laser scanning microscopy. Up to 3 h after glucose replenishment, differential temporospatial induction of IEG-coded transcription factors of the FOS, JUN and KROX families were observed in moderately injured neuronal subpopulations, including the majority of dentate granule cells and CA3 neurons. At later time points, however, a delayed and persistent c-JUN expression was found in severely, but reversibly, injured CA1 neurons and in neurons in the immediate vicinity of irreversibly damaged neurons in the crest of the dentate gyrus. Similar to the results with experimental models of central and peripheral axotomy, selective c-JUN induction in these neurons may represent an initial event in the regeneration process of sublethally injured neurons. In contrast to other models of excitotoxic injury such as ischemia and epilepsy, marked glial c-FOS expression was restricted to astrocytes, as assessed by confocal laser scanning microscopy.
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PMID:Hypoglycemia-elicited immediate early gene expression in neurons and glia of the hippocampus: novel patterns of FOS, JUN, and KROX expression following excitotoxic injury. 759 60


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