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 study was to determine whether ischemia-reperfusion (I/R) of the small bowel activated mast cells and, if so, to determine whether this event contributed to granulocyte infiltration and mucosal barrier dysfunction. Autoperfused segments of the jejunum were exposed to 30 min of ischemia followed by 60 min of reperfusion. Epithelial permeability was assessed by the clearance of 51Cr-labeled EDTA from plasma to lumen. Plasma rat mast cell protease II (RMCP II) was measured and used as an index of mucosal mast cell degranulation, whereas myeloperoxidase (MPO) activity was used as an index of granulocyte infiltration. I/R caused a significant increase in plasma RMCP II levels, MPO activity, and epithelial permeability. The mucosal mast cell stabilizer doxantrazole prevented the I/R-induced increase in all three parameters. The connective tissue mast cell stabilizer ketotifen had no effect. To determine whether oxidants were involved in mast cell degranulation, some animals were pretreated with superoxide dismutase and catalase. This regimen completely abolished the I/R-induced rise in plasma RMCP II levels and attenuated mucosal MPO activity and epithelial permeability. Selective inhibitors of two mast cell-derived mediators, platelet-activating factor and histamine, did not attenuate the rise in epithelial permeability. These data suggest that oxidant-induced mucosal mast cell degranulation is a key event in the granulocyte infiltration and tissue dysfunction associated with reperfusion of the ischemic intestine.
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PMID:Mast cells contribute to ischemia-reperfusion-induced granulocyte infiltration and intestinal dysfunction. 807 30

Recent studies suggest that granulocytes (PMNs) play a role in the pathogenesis of acute and chronic myocardial ischemia and extension of myocardial injury. Granulocytes can release a variety of mediators tissue injury and synergize with these different mediators, cytokines and other cells resulting in amplification of neutrophil stimulation and rising to additional products with enhanced endothelial injury. Free radicals released by PMNs during ischemia or reperfusion produce deleterious effects on cell membranes, endothelial cells and myocardium. Experience in humans shows the modification of PMNs function in angina and during myocardial ischemia: upon reperfusion PMNs accumulate and produce an inflammatory response leading to endothelial injury. Rabbit derived antiserum dependent-reduction of circulating PMNs in the dog or using monoclonal antibody anti-CD11b/CD18 of PMNs resulted in smaller myocardial infarction. Another aspect of PMNs function is related to leukotriene C4 release; the vasoconstrictor effect of this leukotriene on coronary arteries is synergistic with that induced by platelet-released thromboxane A2, and the decrease in coronary flow produced by the combination of both substances is greater than the sum of changes caused by the two eicosanoids separately administered. The potential role of leukocytes, oxygen radicals, leukotrienes and granulocyte enzymes in the pathophysiology of myocardial injury due to regional ischemia and reperfusion is an area of intense investigation. This overview will not attempt to be exhaustive. Experimental and clinical studies to elucidate these events should not only provide insight into acute and chronic pathologic tissue damage, but may also lead to the identification of important new targets of pharmacologic intervention.
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PMID:[The role of the granulocytes in ischemic cardiopathy]. 807 42

The objective of this study was to investigate the effect of hypoxia on the adhesiveness of endothelial cells for granulocytes. Human umbilical vein endothelial cells (HUVEC) were exposed to a PO2 of 7.5 mmHg (1.0 kPa), and the adherence of granulocytes was assessed under continuous hypoxia by means of a hypoxic incubator room. After 2 h of hypoxia the adherence of granulocytes decreased to 50% of the normoxic control, which was not due to a decreased viability of the endothelial cells nor to an increased generation of the antiadhesive factors nitric oxide, prostacyclin, and adenosine. Hypoxia also had no effect on the expression of intercellular adhesion molecule (ICAM)-1 or ICAM-2 on the endothelium. Although the mechanism of the action of hypoxia on the adhesiveness of endothelial cells remains unclear as yet, our data suggest that HUVEC possess a protective mechanism that prevents granulocyte adherence to endothelial cells under extreme hypoxic conditions. The decreased adherence seems paradoxical to the in vivo situation for which the increased margination of granulocytes within the vascular compartment of the ischemic tissue has been observed. However, hypoxia did not impair the potential adhesiveness of HUVEC, since stimulation of endothelial cells under hypoxic conditions with calcium ionophore or lipopolysaccharide increased the adherence of granulocytes in a similar fashion as under normoxic conditions. We therefore conclude that the increased margination of granulocytes during ischemia may be accomplished by the additional stimulation of hypoxic endothelial cells.
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PMID:Effect of hypoxia on adherence of granulocytes to endothelial cells in vitro. 809 91

Although the microvascular compartment contributes significantly to intravascular volume, its importance to disease is often underestimated. Events surrounding cerebral ischemia and recent interest in strategies which may lead to cerebral artery reperfusion in thrombotic or embolic stroke have raised enquiries about the role(s) the microvasculature may play during ischemia and reperfusion. Except in a few instances, little is known about the organization of the microvasculature in cerebral tissue. However, it is apparent that ischemia, inflammatory insults, and infectious processes affect the cerebral microvascular endothelia, cellular elements of the circulating blood compartment, and hemostasis. The precise mechanisms are under study. Observations in isolated microvascular systems from brain tissue, direct visualization of the pial cortical vasculature, and in situ preparations which allow study of the subcortical microvasculature have added to our understanding of these processes. During focal cerebral ischemia and reperfusion alterations of endothelial cell reactivity, coagulation system activation, and granulocyte-endothelial cell interactions are a few of the events affecting microvascular integrity which have been documented. Oxygen free radical generation, selectin and integrin expression and intercellular adhesion, vasomotor responses, endothelial permeability changes, and coagulation system and platelet activation are some of the microvascular processes currently under study which appear to be triggered during ischemia and reperfusion. In view of these events the responses of the cerebral microvasculature to ischemic injury remain relatively unexplored.
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PMID:Microvascular changes during cerebral ischemia and reperfusion. 818 69

Leukocyte depletion improves early postischemic ventricular performance in neonatal models of global myocardial ischemia. However, the rate of leukocyte reaccumulation after cardiopulmonary bypass and its subsequent impact on myocardial function is not known. This laboratory study examined the effect of leukocyte depletion on myocardial performance during the initial 6-hour period after bypass in an in situ, in vivo porcine model of neonatal cardiac surgery. Fifteen 3- to 5-day-old piglets (eight control and seven leukocyte depleted animals) were instrumented by placement of left ventricular short-axis sonomicrometry crystals and an intraventricular micromanometer catheter. Mechanical leukocyte depletion was achieved with Pall RC100 filters (Pall Biomedical, Inc., Fajardo, Puerto Rico) in the cardiopulmonary bypass circuit. Neonatal hearts were subjected to 90 minutes of hypothermic ischemia after a single dose of cold crystalloid cardioplegia. Two control animals died after the operation and were excluded from data analysis. Leukocyte filtration reduced the granulocyte count during initial myocardial reperfusion to 0.8% of control values. However, circulating granulocyte counts increased in leukocyte depleted animals throughout the postoperative period, reaching 68% of control values by 6 hours. Despite this rapid return of circulating granulocytes, animals subjected to leukocyte depletion had significantly better preservation of left ventricular performance (measured by preload recruitable stroke work, p < or = 0.02), left ventricular systolic function (measured by end-systolic pressure-volume relationship, p < or = 0.05), and ventricular compliance (p < or = 0.04) during the experiment. These changes in ventricular function were associated with a significant increase in left ventricular water content (p < or = 0.02) and tissue myeloperoxidase activity (p < or = 0.005) in control animals compared with leukocyte depleted animals. This study demonstrates that leukocyte depletion during initial reperfusion results in sustained improvement in postischemic left ventricular function despite the rapid return of granulocytes to the circulation.
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PMID:Temporary leukocyte depletion reduces ventricular dysfunction during prolonged postischemic reperfusion. 823 Dec 1

Neonatal cardiac surgical procedures continue to be associated with a considerable incidence of severe post-operative ventricular dysfunction. The role of neutrophils in mediating such injury has recently been proposed but remains controversial. The present study was undertaken to examine the potential benefits of leukocyte depletion for myocardial preservation using an in situ, in vivo porcine model of neonatal cardiac surgery. Sixteen 3- to 5-day-old piglets, 8 controls and 8 leukocyte-depleted animals (LD group), underwent 90 minutes of hypothermic ischemia. Mechanical leukocyte filtration during cardiopulmonary bypass reduced the granulocyte count in the initial reperfusate to 0.7% of controls. This was associated with a reduction in leukocyte sequestration in the coronary vascular bed (p < 0.005), a decrease in myocardial creatine kinase release (p < 0.02), and a reduction in coronary vascular resistance (p < 0.03). These changes in physiological response to ischemia were associated with improved postischemic recovery of left ventricular systolic function in LD animals (p < 0.05), although there was no significant improvement in diastolic function. Application of this technique in neonatal cardiac operations may improve myocardial protection and reduce the associated morbidity and mortality.
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PMID:Leukocyte depletion in a neonatal model of cardiac surgery. 838 Feb 45

Recently, we demonstrated that O2- generated in in situ tissues could be detected with cypridina luciferin analog (CLA) as a chemiluminescence probe and a sensitive photon counting system as the detector of chemiluminescence. With these, we examined whether or not O2- generates in in situ gastric mucosa of rats under the conditions to induce experimental acute gastric mucosal lesions (AGMLs) and ischemia-reperfusion of gastric mucosa. The results obtained were as follows: (1) O2- generated by activated granulocytes was detected at a time at which the gastric mucosal blood flow had already decreased in experimental AGMLs and the ischemia-reperfusion system. (2) The edema and erosion formation occurred in the fundic gastric mucosa due to granulocyte mediation. (3) The edema formation was inhibited by a continuous infusion of superoxide dismutase at a time at which the O2- was being generated, but the erosion formation was not inhibited in the same experiment. These results indicate that granulocyte activation, which induces the tissue injury, occurs in the gastric mucosa in an early developmental phase in AGMLs due to the injury to the circulation, and that O2 is related to the edema formation.
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PMID:[Effects of superoxide anion and granulocytes on in situ gastric mucosa of rat in the development of experimental acute gastric mucosal lesions]. 839 14

The 21-aminosteroid tirilazad mesylate (U74006F) is a lipophilic antioxidant and free radical scavenger that has been reported to attenuate brain or spinal cord injury caused by trauma, stroke, ischemia and reperfusion injury. In this study, we have examined the effect of U74006F in reducing the inflammatory parameters of trinitrobenzene sulfonic acid (TNBS)-induced inflammatory bowel disease (IBD) in rats. To induce IBD, rats were given ethanolic TNBS intracolonically. Rats received either 1) TNBS and U74006F 2) TNBS and vehicle or 3) saline and vehicle. Rats were sacrificed 1, 2 and 3 weeks after IBD induction. Colon to body weight ratio (an index of tissue edema) was markedly increased in the vehicle-treated IBD rats after 1 week of administration of TNBS. The ratio was significantly lower after U74006F treatment and the trend remained even after 3 weeks of chronic inflammation. Myeloperoxidase (MPO) activity in vehicle-treated IBD rats was substantially increased compared with controls during the entire 3 weeks of the experiment. U74006F-treated animals had significantly reduced MPO activity (60% lower) when compared with vehicle-treated animals at the end of the second and third weeks. These observations were confirmed by histopathology studies showing reduced granulocyte infiltration after drug treatment. U74006F treatment decreased basal (by 70%) and fMLP stimulated (by 75%) superoxide generation from colonic tissue from IBD rats compared with vehicle treatment after 2 weeks, but there was no apparent difference in superoxide generation among all three groups after 3 weeks. The results of this study suggested that administration of U74006F effectively reduces the inflammatory parameters in this chronic rat model of IBD. As such, U74006F may be therapeutically beneficial for the treatment of IBD in humans.
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PMID:The 21-aminosteroid tirilazad mesylate can ameliorate inflammatory bowel disease in rats. 855 41

Although treatment with agents that block leukocyte function, including anti-ICAM-1 and doxycycline, reduces experimental central nervous system (CNS) ischemic injury, it is not known how leukocyte subset accumulation is affected by these agents. Using the rat two-vessel occlusion model and immunohistochemistry, we investigated granulocyte (PMN) and monocyte/macrophage (M phi) accumulation at 1 and 4 d postischemia. A total of 24 animals were randomized to sham surgery, or to ischemia with saline, anti-ICAM-1, or doxycycline treatments. No leukocytes were observed in sham animals. At 24 h postischemia, there was a moderate infiltration of PMN and M phi in untreated animals that was significantly decreased with either treatment. At 4 d after ischemia no PMN were identified, with extensive M phi accumulation occurring in untreated animals that was only partially reduced with doxycycline treatment. These results confirm that both anti-ICAM-1 and doxycycline treatments reduce PMN and M phi infiltration at 24 h. Delayed M phi accumulation occurs despite treatment, suggesting that some of these cells represent transformed resident microglia.
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PMID:The influence of antiadhesion therapies on leukocyte subset accumulation in central nervous system ischemia in rats. 856 19

The contribution of granulocytes and their byproducts to acute gastric mucosal lesion (AGML) is unclear. Our previous study showed that granulocytes produced O2- in the gastric mucosa of rats treated with 300 mg/kg of cinchophen (cinchophen ulcer, CU) and in rats subjected to 30 min-ischemia-reperfusion (IR). The present study investigated the effects of granulocytes and O2- on microcirculatory injury (MCI) in the gastric mucosa in both models. To evaluate MCI, we measured the amount of extravasated Evans blue, and monitored changes in blood flow and the formation of vascular casts in the gastric mucosa of rats with and without leukopenia. Mucosal levels of interleukin-8 (IL-8) were also measured, to determine granulocyte migration into the stomach. Our findings were: (1) IL-8 was decreased 30-45 min after CU injection (C-I) or after the start of occlusion (S-O), and levels had increased 90 min after either treatment. (2) Evans blue increased 120-150 min after C-I or S-O. These increases were lower in leukopenic than in non-leukopenic rats. (3) The blood flow decreased after C-I or reperfusion and continued at the same level during the 180-min measurement period. In CU leukopenic rats, the blood flow decreased slowly and was restored gradually. In IR leukopenic rats, the blood flow did not decrease. (4) There was a partial lack of capillary network, narrowing of capillaries, and extravasation of resin 90-120 min after C-I and S-O, and the disturbances were reduced in leukopenic rats in both models. (5) The extravasation of resin was reduced by the administration of superoxide dismutase (SOD) at the time O2- from granulocytes was being produced. (6) These reductions in the extravasation of resin due to leukopenia or SOD were smaller in CU than in IR rats. These findings indicate that granulocytes and O2- contribute to some extent to the MCI in CU rats.
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PMID:Effects of activated granulocytes and O2- on microcirculatory injury in acute gastric mucosal lesion in rats induced by sodium cinchophen. 868 May 32


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