Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Chemoattractant cytokines, the chemokines, play an important role in early events of inflammation at the site of tissue damage. We examined the expression of mRNA and the protein products of two such chemokines; i.e. monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1 alpha (MIP-1 alpha) in the ischemic brain tissue following middle cerebral artery occlusion (MCAo). The mRNA transcripts of MCP-1 and MIP-1 alpha were detected by Northern hybridization and reverse transcriptase polymerase chain reaction (RT/PCR), respectively, and the anatomic distribution of specific proteins was analyzed by immunohistochemistry. We found that MCP-1 mRNA was not expressed in the brains of normal rats or rats sacrificed 2 h after MCAo. 6 h after the induction of cerebral ischemia, weak expression of both mRNAs was detected in the ischemic tissue. mRNAs were expressed up to 48 h, and were markedly attenuated at 96 h. In the rats subjected to MCA occlusion, MCP-1 immunoreactivity was diffusely expressed and localized to the ischemic area, and was most intense at 48 h after MCA occlusion. Endothelial cells and macrophage-like cells expressed MCP-1 protein in the ischemic brain. The distribution and morphology of MIP-1 alpha immunoreactive cells were identical with activated astrocytes. We conclude that MCP-1 and MIP-1 alpha mRNAs and proteins are induced after cerebral ischemia in the rat. They may have a role in promoting inflammatory and/or repair processes in the ischemic brain, possibly by attracting or modulating inflammatory cells in the ischemic area.
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PMID:Expression of monocyte chemoattractant protein-1 and macrophage inflammatory protein-1 after focal cerebral ischemia in the rat. 786 Jul 8

To systematically elucidate the gene expression of inflammatory and immune modulators following middle cerebral artery occlusion (MCAO) in the rat, we studied interleukin-10 (IL-10) along with tumor necrosis factor alpha (TNF-alpha), interleukin-1 beta (IL-1beta) and interleukin-2 (IL-2). Gene expression of these cytokines was studied ipsilateral and contralateral to the MCAO, with mRNA expression levels evaluated 2, 4, 6, 8 and 12 h following permanent MCAO by reverse transcriptase polymerase chain reaction (RT-PCR). In the ischemic hemisphere TNF-alpha and IL-1beta mRNA increased at 2 h following MCAO and peaked at 6 h, with IL-10 mRNA detected only at 6 h. Contralaterally, both TNF-alpha and IL-1beta mRNAs were expressed with a similar pattern to that in the ischemic hemisphere, but at lower levels, with no contralateral IL-10 expression. There was no difference in IL-2 gene expression between control and experimental animals in either hemisphere. These results demonstrate that IL-10 and TNF-alpha, IL-1beta gene expression is induced early following MCAO. The temporal profile of these cytokines is similar to that seen in sepsis, where TNF-alpha induces IL-10; subsequently IL-10 inhibits TNF-alpha expression. The similarity of the temporal profile of cytokine expression in sepsis and cerebral ischemia suggests that IL-10 should be studied as a potential inhibitor of TNF-alpha production in ischemic brain tissue. The factors inducing contralateral expression of the inflammatory cytokines, TNF-alpha and IL-1beta, along with the potential clinical significance of this remote cytokine gene expression, merit further study.
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PMID:Gene expression of IL-10 in relationship to TNF-alpha, IL-1beta and IL-2 in the rat brain following middle cerebral artery occlusion. 941 30

There is increasing evidence that the inflammatory response plays an important role in CNS ischemia. The murine model of focal ischemia, however, remains incompletely characterized. In this study we examined expression of several cytokines and the vascular adhesion molecule E-selectin, in order to characterize the molecular events following stroke in the C57BL/6J mouse. Using a multi-probe RNAse protection assay (RPA), mRNA for 19 cytokines was analyzed following permanent and transient occlusion of the middle cerebral artery in mice. In addition, samples from the same mice were analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR) to evaluate E-selectin mRNA expression levels. Several cytokine mRNAs showed a similar expression pattern in both permanent and transient CNS ischemia while others showed a temporal expression pattern that was dependent on the type of stroke. For both models, mRNA levels of TNFalpha rose early (4 h) followed by IL-6 (10-18 h) and a comparatively late increase (96 h) in TGFbeta1. IL-1alpha, IL-1beta and IL-1ra levels showed a model dependent shift in temporal expression. Reperfusion appeared to delay the induction of these cytokines. Temporal changes in cytokine mRNA expression in the mouse CNS occur following ischemic damage. Our findings demonstrate the utility and power of multi-probe RPA for evaluation of changes in cytokine mRNA levels. Moreover, this study is, to our knowledge the first to show temporal changes in cytokine mRNA in mouse cerebral ischemia, forming a basis for further exploration of the roles of these cytokines in modulating ischemic neuronal damage in this model.
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PMID:Temporal modulation of cytokine expression following focal cerebral ischemia in mice. 1002 29

We have used a rat model of focal cerebral ischemia to investigate changes in gene expression that occur during stroke. To monitor these changes, we employed representational difference analysis-polymerase chain reaction (PCR). A total of 128 unique gene fragments were isolated, and we selected 13 of these for quantitative reverse transcriptase-PCR analysis. Of these 13 genes, we found seven that were differentially expressed. Four of these genes have not previously been implicated in stroke, and include neuronal activity regulated pentraxin (Narp), cysteine rich protein 61 (Cyr61), Bcl-2 binding protein BIS (Bcl-2-interacting death suppressor), and lectin-like ox-LDL receptor (LOX-1). We demonstrated differential expression of each gene by quantitative PCR analysis, and in the case of LOX-1, we further confirmed differential expression by in situ hybridization. LOX-1 expression is induced greater than ten fold at the core lesion site, and is essentially localized to the ipsilateral half of the brain. LOX-1 appears to be expressed in a non-neuronal cell type, and it does not appear to be expressed in vascular endothelial cells within the brain. This suggests that LOX-1 may serve a novel function in the brain.
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PMID:Identification of differentially expressed genes induced by transient ischemic stroke. 1200 27

Our laboratory has developed a competitive reverse transcriptase polymerase chain reaction (RT-PCR) procedure to analyse the mRNA expression of the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptor subunits in single cells. By the use of an internal RNA standard competing equally with the four subunit's mRNA, we have analysed 283 whole single hippocampus CA1 cells from adult rat brain. The cells were sampled from three groups of animals: one control group, one group subjected to preconditioning ischemia, and one group subjected to global cerebral ischemia. After reverse-transcription and PCR-amplification of mRNA in the cells, the PCR product was digested using subunit specific endonucleases and quantified by Cy-5 fluorescence. The median mRNA copy numbers achieved from control rats were 290, 247, 207, and 16 GluR1-4, respectively.
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PMID:Competitive quantitative measurement of the AMPA receptor gene expression at the single cell level. 1211 75

Hypoxic preconditioning (8% O2, 3 h) produces tolerance 24 h after hypoxic-ischemic brain injury in neonatal rats. To better understand the ischemic tolerance mechanisms induced by hypoxia, we used oligonucleotide microarrays to examine genomic responses in neonatal rat brain following 3 h of hypoxia (8% O2) and either 0, 6, 18, or 24 h of re-oxygenation. The results showed that hypoxia-inducible factor (HIF)-1- but not HIF-2-mediated gene expression may be involved in brain hypoxia-induced tolerance. Among the genes regulated by hypoxia, 12 genes were confirmed by real time reverse transcriptase-PCR as follows: VEGF, EPO, GLUT-1, adrenomedullin, propyl 4-hydroxylase alpha, MT-1, MKP-1, CELF, 12-lipoxygenase, t-PA, CAR-1, and an expressed sequence tag. Some genes, for example GLUT-1, MT-1, CELF, MKP-1, and t-PA did not show any hypoxic regulation in either astrocytes or neurons, suggesting that other cells are responsible for the up-regulation of these genes in the hypoxic brain. These genes were expressed in normal and hypoxic brain, heart, kidney, liver, and lung, with adrenomedullin, MT-1, and VEGF being prominently induced in brain by hypoxia. These results suggest that a number of endogenous molecular mechanisms may explain how hypoxic preconditioning protects against subsequent ischemia, and may provide novel therapeutic targets for treatment of cerebral ischemia.
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PMID:Brain genomic response following hypoxia and re-oxygenation in the neonatal rat. Identification of genes that might contribute to hypoxia-induced ischemic tolerance. 1214 88

To investigate the expression of the HO-1 gene in PC12 cells in hypoxic environment and gain further insight to the role of HO-1 in cerebral ischemia, PC12 cells were exposed to hypoxia environment (95% N2, 5% CO2) for 0.5 h, 1 h, 4 h, 8 h, 12 h, 24 h respectively. The level of HO-1 mRNA was examined by reverse transcriptase polymerase chain reaction (RT-PCR); the volume of COHb in the media were measured spectrophotometrically and the cGMP concentration of PC12 cell extracts was determined by radioimmunoassay. We found that after exposure to hypoxia for 1 h, 4 h, 8 h, 12 h, 24 h, HO-1 mRNA increased by 3%, 4%, 17%, 31% 36% as compared with that in control group respectively (P < 0.01 or P < 0.05); the COHb increased by 12%, 29%, 59%, 88%, 94% as compared with that in control group respectively (P < 0.01 or P < 0.05), and the cGMP concentration were 2.2, 3.4, 5.2, 8.1, 10.9-fold as that of the control group (P < 0.01). We are led to conclude that hypoxia induced the expression of HO-1 gene, the production of endogenous CO, and the concentration of cGMP was elevated as well.
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PMID:Induction of the expression of heme oxygenase gene in PC12 cells by hypoxia. 1267 63

Rapid progress in the development of highly active antiretroviral therapy has changed the observed patterns in HIV encephalitis and AIDS-related CNS opportunistic infections. Early in the AIDS epidemic, autopsy studies pointed to a high prevalence of these conditions. With the advent of nucleoside reverse transcriptase inhibitors, the prevalence at autopsy of opportunistic infections, such as toxoplasmosis and progressive multifocal leukoencephalopathy, declined while that of HIV encephalitis increased. After the introduction of protease inhibitors, a decline in both HIV encephalitis and CNS opportunistic infections was observed. However, with the increasing resistance of HIV strains to antiretrovirals, there has been a resurgence in the frequency of HIV encephalitis and HIV leukoencephalopathy. HIV leukoencephalopathy in AIDS patients failing highly active antiretroviral therapy is characterized by massive infiltration of HIV infected monocytes/macrophages into the brain and extensive white matter destruction. This condition may be attributable to interactions of anti-retrovirals with cerebrovascular endothelium, astroglial cells and white matter of the brain. These interactions may lead to cerebral ischemia, increased blood-brain barrier permeability and demyelination. Potential mechanisms of such interactions include alterations in host cell signaling that may result in trophic factor dysregulation and mitochondrial injury. We conclude that despite the initial success of combined anti-retroviral therapy, more severe forms of HIV encephalitis appear to be emerging as the epidemic matures. Factors that may contribute to this worsening include the prolonged survival of HIV-infected patients, thereby prolonging the brain's exposure to HIV virions and proteins, the use of increasingly toxic combinations of poorly penetrating drugs in highly antiretroviral-experienced AIDS patients, and selection of more virulent HIV strains with higher replication rates and greater virulence in neural tissues.
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PMID:Changing patterns in the neuropathogenesis of HIV during the HAART era. 1274 73

The objective of this study is to investigate the anti-inflammatory effect of hydroxyethylpuerarin on focal brain ischemia injury in rats and to explore its mechanisms of action. After 24 h of reperfusion following 2 h of cerebral ischemia, the infiltration of neutrophils was observed by myeloperoxidase (MPO) activity determination, the expression of intercellular adhesion molecule-1 (ICAM-1) was observed by western blot and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis, and the nuclear translocation and DNA binding activity of nuclear factor-kappaB (NF-kappaB) were observed by western blot and electrophoretic mobility shift assay (EMSA). The results showed that hydroxyethylpuerarin could obviously inhibit the MPO activity and ICAM-1 expression following 2 hours of ischemia with 24 hours of reperfusion. The nuclear translocation and DNA binding activity were also decreased by hydroxyethylpuerarin treatment. These results suggested that hydroxyethylpuerarin could inhibit neutrophil-mediated inflammatory response after brain ischemia reperfusion in rats. This effect may be mediated by down-regulation of ICAM-1 and NF-kappaB activity.
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PMID:Anti-inflammatory effect of hydroxyethylpuerarin on focal brain ischemia/reperfusion injury in rats. 1580 53

The activation of glutamate receptors, particularly N-methyl-D-aspartate (NMDA) receptors, initiates ischemic cascade in the early stages of cerebral ischemia. Postischemia, cerebral ischemia is also associated with an inflammatory reaction that contributes to tissue damage. The up-regulation of neuronal cyclooxygenase-2 (COX-2) and elevation of prostaglandin E2 (PGE2) have been reported to occur after cerebral ischemic insult. We therefore studied whether the COX-2 reaction product PGE2 affects glutamate receptor-mediated cell death in cultured rat cortical cells. PGE2 was found to augment NMDA-mediated cell death. The transcription of EP1, EP2, EP3 and EP4 PGE2 receptor genes was investigated using reverse transcriptase-polymerase chain reaction (RT-PCR). EP1, EP2 and EP3 receptor genes were found in cortical cells. Butaprost (an EP2 agonist) markedly enhanced NMDA-mediated cell death, whereas 17-phenyl trinor-PGE2 (an EP1 agonist) and sulprostone (an EP3 agonist) had little effect. Both PGE2 and butaprost elevated cAMP intracellular levels in the cortical cells; moreover, forskolin, an activator of adenylate cyclase, enhanced NMDA-mediated cell death. These results suggest that PGE2, acting via EP2 receptors, aggravates excitotoxic neurodegeneration by a cAMP-dependent mechanism.
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PMID:Prostaglandin E2 deteriorates N-methyl-D-aspartate receptor-mediated cytotoxicity possibly by activating EP2 receptors in cultured cortical neurons. 1630 9


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