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

The objective of this article is to illustrate both the potential and the limitations of molecular imaging in stroke research. By molecular imaging we mean the visual representation of biological processes at the cellular and molecular level. The use of molecular imaging for stroke diagnosis is still at a very preliminary stage and many of these procedures have only been tested in animals. In rats, stroke therapy using stem cells can be monitored by magnetic resonance imaging (MRI), green fluorescent protein (GFP) or luciferase (LUC) imaging. The migration of macrophages, which take up intravenously administered iron-based contrast agents and then migrate to the area of infarction, can already be observed in stroke patients. With MRI, the new agent Gd-DTPA-sLexA that binds to E- and P-selectin can specifically visualize selectin-mediated early endothelial activation after transient focal ischemia "in vivo". Decreased glial fibrillary acidic protein (GFAP) gene expression can be imaged in vivo by scintigraphy 24 hours after cerebral ischemia using a peptide nucleic acid antisense conjugate labeled with 111In and that hybridizes to the rat GFAP mRNA. Technetium-99m hydrazine nicotinamide-labeled HYNIC-annexin V SPECT can not only detect sites of neuronal injury in stroke patients but also can monitor the effects of neuroprotective therapy with a monoclonal antibody raised against FasLigand (FasL) in rats. Finally, information about cell metabolism in the infarct region can be gained using certain intracellular tracers [e.g. 18F-fluoromisonidazole (FMISO)]. Imaging benzodiazepine receptors with 11C-flumazenil (FMZ) can distinguish between irreversibly damaged and viable penumbra tissue early after stroke.
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PMID:Future contrast agents for molecular imaging in stroke. 1762 9

Activation of the receptor for advanced glycation endproducts (RAGE) by its multiple ligands can trigger diverse signaling pathways with injurious or pro-survival consequences. In this study, we show that Rage mRNA and protein levels were stimulated in the mouse brain after experimental stroke and systemic hypoxia. In both cases, RAGE expression was primarily associated with neurons. Activation of RAGE-dependent pathway(s) post-ischemia appears to have a neuroprotective role because mice genetically deficient for RAGE exhibited increased infarct size 24 h after injury. Up-regulation of RAGE expression was also observed in primary neurons subjected to hypoxia or oxygen-glucose deprivation, an in vitro model of ischemia. Treatment of neurons with low concentrations of S100B decreased neuronal death after oxygen-glucose deprivation, and this effect was abolished by a neutralizing antibody against RAGE. Conversely, high concentrations of exogenous S100B had a cytotoxic effect that seems to be RAGE-independent. As an important novel finding, we demonstrate that hypoxic stimulation of RAGE expression is mediated by the transcription factor hypoxia-inducible factor-1. This conclusion is supported by the finding that HIF-1alpha down-regulation by Cre-mediated excision drastically decreased RAGE induction by hypoxia or desferrioxamine. In addition, we showed that the mouse RAGE promoter region contains at least one functional HIF-1 binding site, located upstream of the proposed transcription start site. A luciferase reporter construct containing this RAGE promoter fragment was activated by hypoxia, and mutation at the potential HIF-1 binding site decreased hypoxia-dependent promoter activation. Specific binding of HIF-1 to this putative HRE in hypoxic cells was detected by chromatin immunoprecipitation assay.
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PMID:Hypoxia-inducible factor-1 mediates neuronal expression of the receptor for advanced glycation end products following hypoxia/ischemia. 1794 94

Although ischemia is associated with disruption of cadherin-mediated adhesion in renal cell lines, the impact of decreased cadherin function on the transcriptional activity of beta-catenin remains poorly defined. In these studies, we used a simulated ischemia model in normal rat kidney (NRK) cells to disrupt cadherin function. Cell viability; cadherin/catenin expression, function, and localization; and beta-catenin-mediated transcriptional activity were assessed during ischemia/reperfusion. Following 6 hr of ischemia, a decrease in the expression of E- and N-cadherin was seen that correlated with altered cell morphology indicative of decreased intercellular adhesion. While ischemia was associated with activation of glycogen synthase kinase 3 beta (GSK-3beta), this did not correlate with increased phosphorylation of beta-catenin as assessed by Western blots using phosphoryl-specific antibodies. beta-Catenin was not localized to the nucleus by immunofluorescence in ischemic NRK cells, but rather a strong perinuclear signal was seen in reperfused cells. This was consistent with the finding that neither ischemia nor reperfusion activated the transcriptional activity of beta-catenin as assessed by the TCF-optimal promoter (TOPFlash) construct. However, NRK cells possess a competent Wnt pathway, as challenge with lithium chloride elicited a ten-fold increase in luciferase activity. These results suggest that ischemia-induced disruption of cadherin/catenin complexes is not sufficient to stimulate beta-catenin transcriptional activity in NRK cells.
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PMID:Ischemia-induced cleavage of cadherins in NRK cells is not sufficient for beta-catenin transcriptional activity. 1795 28

The purpose of this study was to monitor hypoxia in an orthotopic liver tumor model using a hypoxia-sensitive reporter imaging system and to image enhanced gene expression after clamping the hepatic artery. C6 and RH7777 Morris hepatoma cells were transduced with a triple reporter gene (HSV1-tk/green fluorescent protein/firefly luciferase-triple fusion), placed under the control of a HIF-1-inducible hypoxia responsive element (HRE). The cells showed inducible luciferase activity and green fluorescent protein expression in vitro. Isolated reporter-transduced Morris hepatoma cells were used to produce tumors in livers of nude rats, and the effect of hepatic artery clamping was evaluated. Tumor hypoxia was shown by immunofluorescence microscopy with the hypoxia marker EF5 [2-(2-nitro-1H-imidazol-1-yl)-N-(2,2,3,3,3-pentafluoropropyl acetamide)] and the fluorescent perfusion marker Hoechst 33342, and by pO(2) electrode measurements. For tumor hypoxia imaging with the HRE-responsive reporter, both luciferase bioluminescence and [(18)F]2'-fluoro-2'-deoxyarabinofuranosyl-5-ethyluracil positron emission tomography was done, and the presence of hypoxia in Morris hepatoma tumors were successfully imaged by both techniques. Transient clamping of the hepatic artery caused cessation of tumor perfusion and severe hypoxia in liver tumors, but not in adjacent liver tissue. These results show that the orthotopic reporter-transduced RH7777 Morris hepatomas are natively hypoxic and poorly perfused in this animal model, and that the magnitude of hypoxia can be monitored using a HRE-responsive reporter system for both bioluminescence and positron emission tomography imaging. However, the severity of tumor ischemia after permanent ligation of the hepatic artery limits our ability to image severe hypoxia in this animal model.
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PMID:Imaging of hypoxia-driven gene expression in an orthotopic liver tumor model. 1798 17

Cerebral ischemia triggers inflammation and apoptosis, and the transcription factor NF-kappaB is a key regulator of both events. Here, we report on the induction of the peptidoglycan recognition protein-S (PGRP-S) in a mouse model of cerebral ischemia. Upregulation was reduced if the NF-kappaB subunit RelA was conditionally deleted in the brain. Regulation of PGRP-S transcription by RelA was confirmed in vitro. Cotransfection of a RelA expression plasmid stimulated the expression of a PGRP-S luciferase fusion gene. Mutation of two NF-kappaB response elements in the PGRP-S promoter disrupted stimulation by RelA. To investigate the function of PGRP-S in cerebral ischemia, we subjected PGRP-S(-/-) mice to cerebral ischemia. However, there was no difference in the infarct size in PGRP-S-deficient mice compared to controls. In summary, the data show that PGRP-S is induced in cerebral ischemia by RelA, but its role in ischemia is unclear.
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PMID:Peptidoglycan recognition protein-S (PGRP-S) is upregulated by NF-kappaB. 1803 91

Oxidative stress is important in several pathologies, including cardiovascular diseases such as atherosclerosis and cardiac ischemia-reperfusion injury. An important mechanism for adaptation to oxidative stress is induction of genes through the antioxidant response element (ARE), which regulates the expression of antioxidant and cytoprotective genes via the transcription factor Nrf2 (nuclear factor E2-related factor 2). As Nrf2-regulated genes are induced during oxidant stress occurring, for example, in reperfusion after ischemia, we took a novel approach to exploit ARE for the development of oxidative stress-inducible gene therapy vectors. To this end, one, two or three ARE-containing regions from human NAD(P)H:quinone oxidoreductase-1, glutamate-cysteine ligase modifier subunit and mouse heme oxygenase-1 were cloned into a vector expressing luciferase under a minimal SV40 promoter. The construct, which was the most responsive to ARE-inducing agents, was chosen for further studies in which a lentiviral vector was produced for an efficient transfer to endothelial cells. Heme oxygenase-1 (HO-1), which has well-characterized anti-inflammatory properties, was used as the therapeutic transgene. In human endothelial cells, ARE-driven HO-1 overexpression inhibited nuclear factor-kappaB activation and subsequent vascular cell adhesion molecule-1 expression induced by tumor necrosis factor-alpha. We conclude that the ARE element is a promising alternative for the development of oxidative stress-inducible gene therapy vectors.
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PMID:Oxidative stress-inducible lentiviral vectors for gene therapy. 1844 15

Effective and targeted delivery of cells to injured organs is critical to the development of cell therapies. However, currently available in vivo cell tracking methods still lack sufficient sensitivity and specificity. We examined, therefore, whether a highly sensitive and specific bioluminescence method is suitable to noninvasively image the organ distribution of administered mesenchymal stem cells (MSCs) in vivo. MSCs were transfected with a luciferase/neomycin phosphotransferase construct (luc/neo-MSC). Bioluminescence of these cells was measured (charge-coupled device camera) after treatment with luciferin, showing a linear increase of photon emission with rising cell numbers. To track these cells in vivo, groups of mice were injected with 1 x 10(5) luc/neo-MSCs/animal and imaged with bioluminescence imaging at various time points. Injection of cells in the suprarenal aorta showed diffuse distribution of cells in normal animals, whereas distinct localization to the kidneys was observed in mice with ischemia- and reperfusion-induced acute kidney injury (AKI). Intrajugular infusion of MSCs demonstrated predominant accumulation of cells in both lungs. In animals with AKI, detectable cell numbers declined over time, as assessed by bioluminescence imaging and confirmed by PCR, a process that was associated with low apoptosis levels of intrarenally located MSCs. In conclusion, the described bioluminescence technology provides a sensitive and safe tool for the repeated in vivo tracking of infused luc/neo-MSCs in all major organs. This method will be of substantial utility in the preclinical testing and design of cell therapeutic strategies in kidney and other diseases.
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PMID:Bioluminescence imaging to monitor the in vivo distribution of administered mesenchymal stem cells in acute kidney injury. 1848 Jan 80

In this study, we used ischemia-induced retinal neovascularization (NV) as a model to investigate the possible role of microRNAs in a clinically important disease process. Microarray analysis demonstrated seven microRNAs (miR-106a, -146, -181, -199a, -214, -424, and -451) that were substantially increased and three microRNAs (miR-31, -150, and -184) that were substantially decreased in ischemic retina. Potential targets for the upregulated microRNAs were not identified, but bioinformatic analysis suggested target genes for the downregulated microRNAs, and these were confirmed using a luciferase reporter assay. Real-time reverse transcriptase PCR confirmed that the substantial levels of miR-31, -150, and -184 present in normal retina were significantly reduced in ischemic retina. Interestingly, constitutive levels of miR-31 and -184 are high in the cornea and lens, two avascular tissues. Intraocular injection of pre-miR-31, -150, or -184 significantly reduced ischemia-induced retinal NV, and injection of pre-miR-31 or -150 also significantly reduced choroidal NV. These data suggest that alteration of microRNA levels contributes to two types of ocular NV, and that injection or enhanced expression of microRNAs is a potential therapeutic strategy.
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PMID:MicroRNAs regulate ocular neovascularization. 1850 Feb 51

IL-20, an IL-10 family member, is involved in various inflammatory diseases, such as psoriasis, rheumatoid arthritis, and atherosclerosis. We investigated whether hypoxia in vitro and an in vivo model of ischemic stroke would up-regulate IL-20 expression. In vitro, IL-20 expression increased in hypoxic HaCaT, HEK293 cells, chondrocytes, monocytes, and glioblastoma cells. Inhibition of hypoxia-inducible factor 1alpha inhibited CoCl(2)-induced IL-20 expression. We identified two putative hypoxia response elements in the human il20 gene promoter. Promoter activity assays showed that CoCl(2) mimicked hypoxia-activated luciferase reporter gene expression. In vivo, experimental ischemic stroke up-regulated IL-20 in the sera and brain tissue of rats. IL-20 stained positively in glia-like cells in peri-infarcted lesions, but not in contralateral tissue. Administration of IL-20 mAb ameliorated ischemia-induced brain infarction of rats after experimental ischemic stroke. In vitro, RT-PCR analysis showed that glioblastoma cells, GBM8901, expressed IL-20 and its receptor subunits IL-20R1, IL-20R2, and IL-22R1. IL-20 induced cell proliferation in GBM8901 cells by activating the JAK2/STAT3 and ERK1/2 pathways. IL-20 also induced production of IL-1beta, IL-8, and MCP-1 in GBM8901 cells. We conclude that IL-20 was responsive to hypoxia in vitro and in the ischemic stroke model and that up-regulation of IL-20 in the ischemic brain may contribute to brain injury.
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PMID:IL-20 is regulated by hypoxia-inducible factor and up-regulated after experimental ischemic stroke. 1934 80

The aim of the present study was to evaluate the protective effect of cryptotanshinone (CTS), one of active ingredients of Salvia miltiorrhiza root, on myocardial ischemia-reperfusion injury in rat due to inhibition of some inflammatory events that occur by NF-kappaB-activation during ischemia and reperfusion. Myocardial ischemia and reperfusion injury was induced by occluding the left anterior descending coronary artery for 30 min followed by either 2 h (biochemical analysis) or 24 h (myocardial function and infarct size measurement) reperfusion. CTS injected (i.v.) 10 min before ischemia and reperfusion insult. CTS significantly reduced the infarct size and improved ischemia and reperfusion-induced myocardial contractile dysfunction. Furthermore, CTS inhibited NF-kappaB translocation, expression of pro-inflammatory cytokines (TNF-alpha, IL-1beta, IL-6), neutrophil infiltration and MPO activity in ischemic myocardial tissues. CTS also significantly reduced plasma levels of TNF-alpha, IL-1beta due to ischemia and reperfusion. Interestingly, H(2)O(2)-stimulated NF-kappaB-luciferase activity and TNF-alpha-induced expression of vascular cell adhesion molecule-1 (VCAM-1) and intracellular adhesion molecule-1 (ICAM-1) expressions in human umbilical vein endothelial cells (HUVEC) were significantly inhibited by CTS. Taken together, it is concluded that CTS may attenuate ischemia and reperfusion-induced microcirculatory disturbances by inhibition of proinflammatory cytokine production, reduction of neutrophil infiltration and possibly inhibition of adhesion molecules through inhibition of NF-kappaB-activation during ischemia and reperfusion.
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PMID:Cryptotanshinone, a lipophilic compound of Salvia miltiorrriza root, inhibits TNF-alpha-induced expression of adhesion molecules in HUVEC and attenuates rat myocardial ischemia/reperfusion injury in vivo. 1940 Nov 98


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