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

Recent studies implicate a role for granulocytes in the genesis of the microvascular and parenchymal cell dysfunction, which occurs upon reperfusion of ischemic tissues. Although the molecular mechanisms underlying this neutrophil-mediated injury are not completely understood, it is clear that an essential first step in granulocyte migration from the vascular lumen to the interstitial space is adherence to vascular endothelium. The purpose of this study was to determine whether prevention of neutrophil adherence with monoclonal antibody IB4 directed against the neutrophil CD11/CD18 glycoprotein adherence complex or neutrophil depletion with a specific polyclonal antineutrophil serum would attenuate the microvascular dysfunction seen in postischemic skeletal muscle. Changes in vascular permeability were assessed by measurement of the solvent drag reflection coefficient for total plasma proteins (sigma) in isolated canine gracilis muscle subjected to ischemia/reperfusion, ischemia/reperfusion plus antineutrophil serum, or ischemia/reperfusion plus IB4. Estimates of sigma averaged 0.83 +/- 0.04 in nonischemic, control gracilis muscles, while ischemia/reperfusion was associated with a marked increase in vascular permeability (decrease in sigma to 0.54 +/- 0.04) and vascular resistance (increased by 135 +/- 41% over the control value). Prevention of neutrophil adherence or neutrophil depletion prevented this increase in vascular permeability (sigma = 0.80 +/- 0.03 and 1.01 +/- 0.06, respectively) and resistance (decrease of 16.51 +/- 8.0% and increase of 2.4 +/- 4.6% over control values, respectively). The results of this study suggest that neutrophils play a critical role in the genesis of microvascular dysfunction in postischemic skeletal muscle. Furthermore, neutrophil adherence to vascular endothelium appears to be a prerequisite for the production of this injury.
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PMID:Neutrophil-mediated microvascular dysfunction in postischemic canine skeletal muscle. Role of granulocyte adherence. 215 91

Thrombolytic therapy has gained widespread acceptance as a means of treating coronary artery thrombosis in patients with acute myocardial infarction. Although experimental data have demonstrated that timely reperfusion limits the extent of infarction caused by regional ischemia, there is growing evidence that reperfusion is associated with an inflammatory response to ischemia that exacerbates the tissue injury. Ischemic myocardium releases archidonate and complement-derived chemotactic factors, e.g., leukotriene B4 and C5a, which attract and activate neutrophils. Reperfusion of ischemic myocardium accelerates the influx of neutrophils, which release reactive oxygen products, such as superoxide anion and hydrogen peroxide, resulting in the formation of a hydroxyl radical and hypochlorous acid. The latter two species may damage viable endothelial cells and myocytes via the peroxidation of lipids and oxidation of protein sulfhydryl groups, leading to perturbations of membrane permeability and enzyme function. Neutrophil depletion by antiserum and inhibition of neutrophil function by drugs, e.g., ibuprofen, prostaglandins (prostacyclin and PGE1), or a monoclonal antibody, to the adherence-promoting glycoprotein Mo-1 receptor, have been shown to limit the extent of canine myocardial injury due to coronary artery occlusion/reperfusion. Recent studies have challenged the hypothesis that xanthine-oxidase-derived oxygen radicals are a cause of reperfusion injury. Treatment with allopurinol or oxypurinol may exert beneficial effects on ischemic myocardium that are unrelated to the inhibition of xanthine oxidase. Furthermore, the human heart may lack xanthine oxidase activity. Further basic research is needed, therefore, to clarify the importance of xanthine oxidase in the pathophysiology of reperfusion injury.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Myocardial ischemia and reperfusion: the role of oxygen radicals in tissue injury. 248 90

To determine if inhibition of leukocyte adhesion and aggregation could improve postischemic ventricular dysfunction ("stunning"), a monoclonal antibody (904) that binds to the adhesion-promoting Mo1 glycoprotein on the cell surface of leukocytes was administered intravenously (0.5 mg/kg) to open-chest dogs before a 15-minute coronary occlusion. Ultrasonic crystals placed in ischemic and control myocardium were used to measure systolic wall thickening during a 15-minute occlusion of the left anterior descending artery and for 3 hours after reperfusion. Myocardial blood flow was measured with tracer-labeled microspheres before occlusion, after 10 minutes of occlusion, 3 minutes of reperfusion, and at 1 and 3 hours after reperfusion. Six animals receiving anti-Mo1 antibody had antibody excess demonstrated with immunofluorescence techniques at 5 minutes and 3 hours of reperfusion; this finding indicated saturation of binding sites. Five animals served as controls and received an antibody (murine immunoglobulin G) that does not influence neutrophils. The two groups did not differ hemodynamically during ischemia and reperfusion. Risk areas and myocardial blood flow were also not significantly different between the two groups. The main parameter used to define regional myocardial stunning, percentage systolic wall thickening in the ischemic/reperfused area, did not differ significantly between the two groups. Specimens from nonischemic myocardium were compared with ischemic specimens for myeloperoxidase content. There were no significant differences within or between groups. These data indicate that the anti-Mo1 monoclonal antibody (904) is not effective in improving the profound myocardial dysfunction that persists for 3 hours of reperfusion after 15 minutes of ischemia.
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PMID:F(ab')2 fragments of anti-Mo1 (904) monoclonal antibodies do not prevent myocardial stunning. 255 27

Recent studies suggest that neutrophils are an important factor in the organ injury associated with ischemia and shock. Increased neutrophil-endothelial adhesiveness is essential for neutrophil-mediated vascular injury. To examine the role of neutrophils and neutrophil adhesiveness in the development of injury after hypovolemic shock, and to determine whether this injury is a consequence of reperfusion, we used the monoclonal antibody (MAb) 60.3 (directed to the primary human neutrophil adherence glycoprotein, CD18) to block neutrophil adherence functions at the time of resuscitation in a rabbit model of hemorrhagic shock. None of the unanesthetized control animals subjected to 2 hours of shock (cardiac output, 30% of baseline) followed by resuscitation survived 5 days. All had gross and histologic evidence of injury to lungs, liver, and gastrointestinal mucosa. In contrast, 71% of the animals that received MAb 60.3 immediately before resuscitation survived 5 days (p less than 0.005), and visceral organ injury was absent or markedly attenuated. We conclude that a significant proportion of injury resulting from shock and resuscitation occurs after the ischemic insult and that increased neutrophil adhesiveness plays an important role in the development of multiple organ injury and death following shock and resuscitation (in this model). This injury may be significantly reduced by blocking neutrophil adherence functions with the MAb 60.3--even if administration is delayed until resuscitation.
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PMID:Role of neutrophils in generalized reperfusion injury associated with resuscitation from shock. 277 26

The use of various types of cultured mammalian renal tubular epithelial cells in the study of cell injury has been reviewed. Permanent cell lines, primary explant cultures, monolayers from individually microdissected tubules, isolated cells and organ cultures have been used. In the majority of studies, cultured cells of normal tissue origin have been treated with a noxious agent and alterations in growth, morphology, biochemical and immunological properties studied. Earliest studies examined infection by parasites and bacteria and the effects of plant and bacterial toxins, carcinogens, metabolic and transport inhibitors, cytoskeletal perturbants, general inhibitors of protein, glycoprotein, DNA and RNA synthesis. More recent studies have concentrated on the effects of specific nephrotoxins, such as heavy metals and aminoglycoside antibiotics and of ischemia which have bearing on the pathogenesis of acute renal failure. An additional approach has been to culture diseased renal epithelia of cystic, diabetic or tumor origin and compare their properties with those of normal cultured tubular epithelia. Future studies using cultured renal tubular cells will be valuable in elucidating the cellular and subcellular mechanisms of renal epithelial cell injury in disease.
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PMID:Use of cultured renal tubular cells in the study of cell injury. 300 63

Leukocytes have been shown to play an important role in the development of isolated organ injury after experimental ischemia and reperfusion. To examine the role of leukocytes in generalized ischemia-reperfusion injury we used the MAb 60.3 (directed to the human leukocyte adherence glycoprotein, CD18) to block leukocyte adherence functions in a rabbit model of hemorrhagic shock and resuscitation. In control animals subjected to 1 h of shock (mean blood pressure 45 torr and mean cardiac output 30% of baseline) followed by resuscitation, only 29% survived 5 d. All had gross and histologic evidence of injury to lungs, liver, and gastrointestinal mucosa. In contrast, 100% of the MAb 60.3-treated animals survived 5 d (P less than 0.01) and organ injury was absent or markedly attenuated. The control animals also had a persistent acidosis, lost more weight, and had evidence of continued gastrointestinal bleeding in contrast to MAb 60.3-treated animals. We conclude that increased leukocyte adhesiveness plays an important role in the development of multiple organ injury and death after generalized ischemia-reperfusion and that this injury may be significantly reduced by blocking leukocyte adherence functions with the MAb 60.3.
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PMID:A monoclonal antibody to the adherence-promoting leukocyte glycoprotein, CD18, reduces organ injury and improves survival from hemorrhagic shock and resuscitation in rabbits. 327 7

A monoclonal antibody (904) that binds to a leukocyte cell adhesion-promoting glycoprotein, (Mo1; CD11b/CD18) was administered (1 mg/kg, iv.) to open chest anesthetized dogs 45 min after the induction of regional myocardial ischemia. Ischemia was produced by occluding the left circumflex coronary artery (LCX) for 90 min and then reperfusing for 6 h. There was no difference between control and antibody treated groups with respect to arterial blood pressure, heart rate, or LCX blood flow. Administration of antibody produced no observable effect on circulating neutrophil counts, suggesting that antibody-bound neutrophils were not cleared from the circulation. The mean size of myocardial infarct expressed as percentage of the area at risk of infarction that resulted was reduced by 46% with anti-Mo1 treatment (25.8 +/- 4.7%, n = 8) compared to control (47.6 +/- 5.7%, n = 8; P less than 0.01). The area at risk of infarction was similar between groups. Circulating (serum) antibody excess was confirmed in all 8 anti-Mo1 treated dogs by immunofluorescence analysis. Analysis of ST segment elevation on the electrocardiogram as an indicator of the severity of ischemia suggests that the anti-Mo1 reduces infarct size independent of the severity of ischemia. An additional group of dogs (n = 5) was tested with a control monoclonal antibody of the same subtype (murine IgG1) and was found to produce no significant reduction in myocardial infarct size. Accumulation of neutrophils within the myocardium was significantly attenuated with 904 treatment when analyzed by histological methods. These data demonstrate that administration of anti-Mo1 monoclonal antibody after the induction of regional myocardial ischemia results in reduced myocardial reperfusion injury as measured by ultimate infarct size.
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PMID:Reduction of experimental canine myocardial reperfusion injury by a monoclonal antibody (anti-Mo1, anti-CD11b) that inhibits leukocyte adhesion. 333 35

Renal ischemia causes a reversible loss of microvillar membrane (MVM) of the proximal tubule cell and of MVM enzyme specific activities (S.A.). We sought to determine if recovery of the MVM glycoprotein was accomplished through de novo synthesis or recycling. Renal ischemia (25 min) was induced in rats by occlusion of the left renal artery, followed by 15 min or 4 hrs of reflow of blood. Radiolabelled fucose was injected into rats before or after ischemia and was used as a marker for new glycoprotein synthesis or recycling of prelabelled glycoprotein. Ischemia, followed by 15 min of reflow, caused a 49% reduction in protein associated with the isolated MVM fraction of the ischemic kidney. There was also a decrease in newly fucosylated glycoprotein in both homogenate and MVM fraction measured as S.A. or total amount of labeled glycoprotein. Pre-labelled glycoproteins had no change in S.A. in homogenates or MVM fractions of ischemic or contralateral kidneys. However, the total amount of labeled glycoprotein in the ischemic MVM fraction was reduced. At 4 hrs of reflow, protein content of the MVM fraction was back to normal. Pre-labelled glycoproteins of the ischemic homogenate and MVM fraction were also back to normal with no significant dilution of glycoprotein S.A. by newly synthesized protein, indicating that glycoprotein recycling occurs to a large extent in the ischemic kidney.
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PMID:Glycoprotein reutilization in regenerating microvilli after renal ischemia in rats. 406 83

It is well known that rapid myocardial reperfusion, obtained using thrombolysis and/or PTCA, continues to be the best treatment for evolving myocardial infarction. However, a number of experimental studies have drawn attention to the fact that myocardial recovery following reperfusion may be limited by the onset of numerous deleterious biochemical events which occur during reperfusion. Studies carried out after thrombolysis have shown that the perviousness of the vessel and the existence of flow at the level of the epicardial vessels do not necessarily correspond to the recovery of tissue perfusion since a perfusion defect may persist in the presence of angiographically documented anterograde flow. This discrepancy, which occurs during reperfusion, has been attributed to marked cellular enlargement caused by ischaemia both in irreversibly damaged areas and in those which may potentially recover. In basal conditions, endothelial-neutrophil interaction is inhibited by negatively charged molecules present on endothelial cell membranes and by the production of numerous anti-inflammatory substances. During ischemia, on the other hand, anti-inflammatory and endogenous vasodilating substances are depleted in association with the appearance, on the surface of endothelial cells, of molecules favouring leukocyte adhesion. Of these the glycoprotein which has been characterized in greatest detail is the endothelial leukocyte adhesion molecule (ELAM 1) whose production and appearance on the endothelial surface is linked to cytokine-dependent endothelium activation. Ischemia may also stimulate the activation of neutrophils secreting chemiotactical and vasoconstricting factors, and cytotoxic compounds (reactive oxygen metabolites and proteolyte enzymes).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Damage from reperfusion: no-reflow phenomenon]. 750 96

The objective of this study was to determine whether pulmonary endothelial expression of the adhesive glycoprotein P-selectin contributes to the lung injury and leukostasis observed after intestinal ischemia-reperfusion (I/R). The pulmonary capillary filtration coefficient and lung myeloperoxidase activity were determined in rat lungs isolated after 120 min of superior mesenteric artery occlusion and 90 min of reperfusion. Intestinal I/R resulted in a marked increase in the pulmonary capillary filtration coefficient compared with control and sham-operated rats. The increase in pulmonary microvascular permeability elicited by intestinal I/R was effectively prevented by pretreatment with a P-selectin monoclonal antibody (MAb; MAb PB1.3) but was unaffected by a control MAb. The intestinal I/R-induced increase in pulmonary microvascular permeability was accompanied by a dramatic sequestration of granulocytes in the lung compared with control and sham-operated rats; however, neither the P-selectin nor the control MAbs affected this event. These results indicate that P-selectin contributes to the pulmonary microvascular dysfunction observed after intestinal I/R. The inhibition of intestinal I/R-induced lung injury by immunoneutralization of P-selectin appears to be unrelated to the accompanying lung leukosequestration.
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PMID:Pulmonary microvascular injury after intestinal ischemia-reperfusion: role of P-selectin. 751 Feb 79


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