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

Anesthesized male rabbits having a resting mean arterial pressure of 81 +/- 4 mm Hg and superior mesenteric artery blood flow of 91 +/- 7 mL min-1 were subjected to 60 min of splanchnic ischemia followed by 60 min of reperfusion. Upon reperfusion, mean arterial pressure fell. Splanchnic blood flow also decreased but not in parallel with blood pressure; consequently, vascular resistance was increased over the reperfusion period. This increase in splanchnic vascular resistance was not affected by intravenous t-PA (0.5 mg kg-1 + 5 mg kg-1 hr-1) for 30 min prior to and throughout the reperfusion period or by intravenous L-NAME (1 mg kg-1 x 2). However, intravenous infusions of TGF-beta (18 or 54 micrograms kg-1) at the time of reperfusion dose dependently attenuated the increases in vascular resistance (p < 0.05). This effect of TGF-beta was enhanced by coadministration of t-PA and inhibited by the coadministration of L-NAME. We propose that the effects of TGF-beta are ultimately mediated via nitric oxide release, and conclude that this may be useful therapy for the prevention of reperfusion-associated injury following surgery or as an adjunct to thrombolytic therapy.
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PMID:Transforming growth factor-beta 1 inhibits postischemic increases in splanchnic vascular resistance. 130 30

To understand the complex mechanism(s) involved in molecular responses to ischemia, we developed two experimental models in pigs. In a "stunning" model of repetitive ischemia and reperfusion, we studied the mRNA expression of immediate early genes like c-fos, c-myc and heat shock protein-70 (HSP-70). Myocardial stunning was achieved by two cycles of 10-min left anterior descending coronary artery (LAD) occlusion and 30 min reperfusion. We observed several-fold enhanced expression of c-fos and HSP-70 mRNA in the stunned myocardium as compared with the control, whereas c-myc mRNA levels remained almost unchanged. In the second model, we examined the expression of the peptide mitogens heparin-binding growth factor 1 (HBGF-1) and transforming growth factor beta 1 (TGF-beta 1) after a chronic coronary artery occlusion leading to myocardial collateralization. Progredient stenosis of the circumflex coronary artery was induced by implanting a hygroscopic ameroid constrictor ring around it and occlusion was verified by in vivo angiography. Using polymerase chain reaction (PCR) and Northern hybridization techniques, we observed significantly enhanced expression of HBGF-1 and TGF-beta 1 in collateralized myocardium as compared with normal. In situ techniques revealed the localization of HBGF-1 transcripts in the blood vessel wall, and TGF-beta 1 in cardiac myocytes and Purkinje cells. Our results clearly indicate that myocardial stunning stimulates the expression of transcription factors which might be involved in regulation of certain growth factors like HBGF-1 and TGF-beta 1 which may play a significant role in the development of a collateral circulation.
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PMID:Molecular biology of the coronary vascular and myocardial responses to ischemia. 138 Jun 15

We have studied the development of the collateral circulation in the heart in response to gradual and progressive coronary artery occlusion. When the coronary stenosis becomes critical, tissue ischemia occurs, which we believe leads to the production (and probably to release from storage sites) of tissue hormones (mitogens) that lead to mitosis of endothelial and smooth muscle cells. We have identified from hearts several known mitogens (aFGF, bFGF), non-mitogenic angiogenic factors (TGF-beta), a new anti-mitogen, and a new myocyte-derived growth factor (structures of the last two not yet elucidated). An important principle in the development of collaterals is the remodeling of pre-existing small vessels into the much larger vascular structure. To accommodate new cells old structures have to be removed by controlled proteolysis (tPA, uPA, elastase).
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PMID:Angiogenesis in the adult heart. 171 53

TGF-beta appears to be an important regulatory peptide in cellular physiology. Although all of its actions are not presently known, TGF-beta functions as a cell-switching molecule. In the case of ischemia-reperfusion states, TGF-beta has been shown to exert remarkably effective protective effects. These effects appear to pertain to preservation of endothelial function, particularly to maintenance of EDRF formation by the endothelium. The endothelial protection may be related to actions of TGF-beta opposing the endothelial-destabilizing actions of both TNF and superoxide radicals. However, other important mechanisms will undoubtedly be brought to light with further study of TGF-beta in these situations.
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PMID:Mechanisms of the protective effects of transforming growth factor-beta in reperfusion injury. 193 Feb 56

The influence of the somatostatin analogue angiopeptin on transplant arteriosclerosis was investigated using two aortic transplantation rat models. One was characterized by ischemia/reperfusion-induced changes in syngeneic transplants while immunologically induced changes dominated in the other allogeneic model. Angiopeptin, 100 micrograms/kg per day, was administered continuously until the sacrifice of the rats after 8 weeks. No additional immunosuppression was used in either model. An image analysis system was used to quantify the intimal and medial thicknesses of the grafts. In the syngeneic grafts, the intimal thickness was less than 50% of that of control grafts (P < 0.05), but no difference was seen in the allogeneic model. The expression of selected cells, TGF-beta s, and PDGF and PDGF alpha-receptors was detected immunohistochemically and displayed a similar picture in control and angiopeptin-treated grafts in both models. We conclude that angiopeptin has no clear immunosuppressive properties but may counteract ischemia-induced transplant arteriosclerosis.
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PMID:Effects of angiopeptin on transplant arteriosclerosis in the rat. 776 91

Although transforming growth factor-beta s (TGF-beta s) are expressed widely in both adult and embryonic rat heart, both mRNA and protein expression increase following ischemic injury. Furthermore, exogenous administration of TGF-beta decreases cardiac damage following ischemia-reperfusion in rats. We have found that treatment of primary cultures of neonatal rat cardiomyocytes or cardiac fibroblasts with TGF-beta 1, 2, or 3 results in increased expression of TGF-beta 1, 2, and 3 mRNA. TGF-beta 2 was generally the least effective isoform in inducing TGF-beta expression. In cardiac fibroblasts mRNA expression of all TGF-beta s increased 2-3-fold following 1 h of treatment and decreased to control levels by 8 h which was accompanied by a 2.5- and 2.3-fold increase in TGF-beta 1 and 2 protein secretion, respectively. By 48 h of treatment mRNA levels for TGF-beta s 2 and 3 were less than 10% of control levels. In cardiomyocytes two-five-fold increases in mRNA levels were observed following 1-24 h of TGF-beta 1 treatment, but TGF-beta 1 and 3 mRNA levels returned to control values by 48 h while TGF-beta 2 mRNA expression remained elevated. TGF-beta 1 and 2 protein secreted by the cardiac myocytes was increased 2.9- and 1.7-fold, respectively. Autoinduction of TGF-beta s may play a beneficial role in cardiac wound healing by sustaining transient increases in TGF-beta levels from either endogenous synthesis or exogenous application.
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PMID:Autoinduction of mRNA and protein expression for transforming growth factor-beta S in cultured cardiac cells. 777 87

While the role of cytokines in mediating injury during hind limb skeletal muscle ischemia followed by reperfusion has recently been described, the role of cytokines in myocardial infarction and ischemia/reperfusion have remained relatively unexplored. We hypothesize that cytokines play an important role in the regulation of postischemic myocardial inflammation. This study reports the temporal sequence of proinflammatory cytokine gene expression in postischemic/reperfused myocardium and localizes interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha)-protein by immunostaining. Rats were subjected to either permanent left anterior descending (LAD) occlusion or to 35 minutes of LAD occlusion followed by reperfusion and sacrificed up to 7 days later. Rat-specific oligonucleotide probes were used to semiquantitatively assess the relative expression of mRNA for TNF-alpha, IL-1 beta, IL-2, IL-6, interferon-gamma (IFN-gamma), and transforming growth factor-beta 1 (TGF-beta 1) utilizing the reverse transcriptase-polymerase chain reaction amplification technique. Increased cardiac mRNA levels for all cytokines except IL-6 and IFN-gamma were measurable within 15 to 30 minutes of LAD occlusion and increased levels were generally sustained for 3 hours. During early reperfusion, mRNA levels for IL-6 and TGF-beta 1 were significantly reduced compared with permanent LAD occlusion. In both groups, cytokine mRNA levels all returned to baseline levels at 24 hours, while IL-1 beta, TNF-alpha, and TGF-beta 1 mRNA levels again rose significantly at 7 days only in animals with permanent LAD occlusion. Immunostaining for IL-1 beta and TNF-alpha protein revealed two patterns of reactivity: 1) microvascular staining for both IL-1 beta and TNF-alpha protein only in postischemic reperfused myocardium in early post-reperfusion time points; and 2) staining of infiltrating macrophages in healing infarct zones which was most prominent at 7 days after permanent LAD occlusion. These results provide evidence for local expression of cytokine mRNA in postischemic myocardium and suggest that regulation of local cytokine release is altered during the postischemic period.
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PMID:Cytokine mRNA expression in postischemic/reperfused myocardium. 785 52

Transient global cerebral ischemia induces selective neuronal degeneration in the adult rat hippocampus, which is both preceded and accompanied by activation of microglia and astrocytes. Altered expression patterns of cytokines and growth factors might influence the postischemic neuron-glial interactions as well as the degenerative neuronal processes. Northern blotting of hippocampal tissue from ischemic animals revealed elevated levels of transforming growth factor beta-1 (TGF-beta 1) mRNA, and in the present in situ hybridization study we examine the endogenous expression and cellular localization of TGF-beta 1 mRNA in the adult rat hippocampus at various intervals following 10 min of global cerebral ischemia. Six hours after ischemia, a diffuse expression of TGF-beta 1 mRNA was found throughout the brain, which further intensified until Day 2 and thereafter subsided. In parallel, a massive increase of signal was observed in the hilus fascia dentata from Day 1 and in area CA1 from Day 2 to 4, both areas displaying selective neuronal degeneration. Peak levels of TGF-beta 1 mRNA were found in the hilus around Day 4, whereas expression in the CA1 area persisted through Day 21, the latest time point examined. A similar biphasic response, consisting of a transient, generalized reaction and a persistent lesion-associated activation in areas undergoing selective neuronal degeneration, was previously described for microglia and is reconfirmed in the present study. Cells of the microglial/macrophage lineage thus include the potent modulatory cytokine TGF-beta 1 in their potential repertoire of responses to both CNS activation and lesioning.
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PMID:Cytokines in cerebral ischemia: expression of transforming growth factor beta-1 (TGF-beta 1) mRNA in the postischemic adult rat hippocampus. 789 6

Transforming growth factor-beta 1 (TGF-beta 1) has been shown to be an injury-related peptide growth factor within the mammalian central nervous system. We tested whether TGF-beta 1 has the capacity to protect rat neocortical neurons against excitotoxic damage in vitro and mouse neocortex against ischemic injury in vivo. After 14 days in vitro, cultured neurons from rat cerebral cortex were exposed to 1 mM L-glutamate in serum-free culture medium. The cultures received TGF-beta 1 immediately after the addition of glutamate. Eighteen hours later, the cell viability of the cultures was determined using trypan blue exclusion. TGF-beta 1 (1-10 ng/ml) significantly reduced the excitotoxic neuronal damage in a concentration-dependent manner. In vivo, male NMRI mice were subjected to a permanent occlusion of the left middle cerebral artery by microbipolar electrocoagulation. After 48 h, the animals received a transcardiac injection of carbon black. The area of ischemia (devoid of carbon) was restricted to the neocortex and its size was determined planimetrically by means of an image-analyzing system. The treatment with TGF-beta 1 (1 microgram/kg i.c.v.) at 6, 4, or 2 h prior to vessel occlusion reduced the area of ischemia by 5.3, 10.0, and 9.6%, respectively. The effect of the treatment with TGF-beta 1 was statistically significant (p < 0.05 by two-way ANOVA). The present in vitro and in vivo data suggest that TGF-beta 1 has the capacity to diminish the deleterious consequences of an excitotoxic or ischemic insult.
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PMID:Transforming growth factor-beta 1 prevents glutamate neurotoxicity in rat neocortical cultures and protects mouse neocortex from ischemic injury in vivo. 809 19

The objective of this investigation was to determine the effect of transforming growth factor beta 1 (TGF-beta 1) on endothelium-dependent relaxation in isolated epicardial coronary artery rings obtained from anesthetized dogs after multiple brief episodes of coronary artery occlusion and reperfusion in vivo. Dogs were subjected to four 5-minute periods of left anterior descending coronary artery occlusion interspersed with 5 minutes of reperfusion and followed by a final 1-hour period of reperfusion. Normal left circumflex coronary arteries were used as control samples. Repetitive ischemia and reperfusion significantly (p < 0.01) inhibited the relaxation response to acetylcholine in rings preconstricted with potassium. In an additional group of dogs subjected to the same protocol, 10 micrograms of human recombinant TGF-beta 1 was infused into the left anterior descending coronary artery distal to the site of occlusion via a diagonal branch at 0.3 ml/min immediately before and during the repetitive occlusions and reperfusions. TGF-beta 1 prevented impaired endothelium-dependent relaxation after multiple brief occlusions and reperfusions. These results demonstrate a protective role for TGF-beta 1 in the endothelial injury that occurs during repeated episodes of coronary artery occlusion and reperfusion.
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PMID:Transforming growth factor beta 1 preserves endothelial function after multiple brief coronary artery occlusions and reperfusion. 819 68


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