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

Intestinal ischemia-reperfusion (I/R) provokes polymorphonuclear neutrophil (PMN)-mediated lung injury via a process characterized by circulating PMN priming, pulmonary PMN sequestration, and increased microvascular leak in the lung. We found in rats subjected to intestinal I/R (ischemia 45 min and reperfusion 6 h) that 1) intestinal phospholipase A2 (PLA2) was activated during ischemia, 2) circulating PMN priming (assessed by superoxide production with N-formyl-Met-Leu-Phe) occurred after 1 h reperfusion, and 3) exaggerated 125I-labeled albumin lung leak occurred after 2 h reperfusion, compared with sham-treated animals (P < 0.05). Treatment with a PLA2 inhibitor, quinacrine, within 15 min of reperfusion reversed the exaggerated gut PLA2 activity and abrogated subsequent PMN priming and lung leak (P < 0.05). However, when quinacrine was administered after 2 h of reperfusion, circulating PMN priming and lung leak continued to evolve despite suppression of intestinal PLA2 activity. We conclude that intestinal PLA2 activation may be a prerequisite for the sequelae of circulating PMN priming and pulmonary microvascular leak observed after intestinal I/R.
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PMID:Gut phospholipase A2 mediates neutrophil priming and lung injury after mesenteric ischemia-reperfusion. 790 Aug

Intravital videomicroscopy was used to monitor the migration of leukocytes in rat mesenteric interstitium following exposure of the mesentery to either N-formylmethionyl-leucyl-phenylalanine (FMLP), leukotriene B4 (LTB4), platelet-activating factor (PAF), or ischemia-reperfusion (I-R). All inflammatory stimuli resulted in interstitial migration rates that were higher than those measured in unstimulated extravasated leukocytes. The median migration rate of cells stimulated with FMLP was significantly higher than those observed during superfusion with either LTB4 or PAF or following exposure to I-R. The enhanced leukocyte migration rates elicited by I-R were not attenuated by treatment with PAF- and LTB4-receptor antagonists, suggesting that these lipid mediators are not the inflammatory mediators responsible for I-R-induced leukocyte migration. Additional experiments revealed that the rate of leukocyte migration associated with FMLP stimulation was not significantly altered by either inhibitors of neutrophilic elastase and cathepsin G, a monoclonal antibody directed against the leukocyte adhesion glycoprotein CD11/CD18, or by altering interstitial hydration. This in vivo model provides a useful new approach for defining the factors that modulate leukocyte migration within the extravascular compartment.
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PMID:Modulation of leukocyte migration in mesenteric interstitium. 794 4

Gut ischemia/reperfusion (I/R) induces lung injury by a mechanism that involves neutrophils (PMNs). We have previously shown that endotoxin (LPS), when administered after gut I/R, amplifies this lung injury, while treatment with LPS prior to gut I/R prevents lung injury. The purpose of this study was to determine whether LPS pretreatment (Pre Rx) alters the PMN inflammatory component of the gut I/R injury. Specifically, we focused on whether LPS Pre Rx effected (i) PMN stem cell proliferation, (ii) gut I/R-induced PMN priming, and (iii) gut I/R-induced PMN lung sequestration. Bone marrow was harvested from normal and LPS-pretreated (0.5 mg/kg, ip, 3 days prior) rats, and colony forming units--granulocyte/macrophage (CFU-GM) were quantitated using a soft agar culture technique. In another experiment, normal and LPS-pretreated rats were subjected to gut I/R (45 min superior mesenteric artery occlusion/6 hr reperfusion), and blood and lungs were then harvested. The in vivo priming of PMN was assessed by measuring the difference in superoxide production (O2-) with and without the activating stimulus, N-formylmethionyl-leveyl-phenylalanine (fMLP). The quantity of myeloperoxidase (MPO) was used as an index of the number of PMN sequestered in lung tissue.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Endotoxin pretreatment inhibits neutrophil proliferation and function. 804 Nov 48

The effect of an inhibitor of protein kinase, HA1077 [1-(5-isoquinolinesulfonyl)-homopiperazine HCl], and its hydroxylated metabolite, HA1100, on the activation of NADPH oxidase in human neutrophils were studied. Cells were preincubated with each drug for 10 min and then activated by treatment with phorbol myristate acetate (PMA) or formylmethionyl leucyl phenylalanine (FMLP). After activation, the rate of superoxide dismutase-inhibitable reduction of cytochrome c was estimated. HA1077 and HA1100 inhibited the PMA-induced production of O2- by neutrophil NADPH oxidase in a concentration-dependent manner (IC50 = 15 and 24 microM, respectively). The sensitivity of the FMLP-induced production of O2- to these drugs was similar. The production of O2- in 1,25-dihydroxyvitamin D3-treated HL-60 cells, which differentiated to macrophage-like cells, was also inhibited by the drugs. The extent of inhibition by HA1077 was almost the same as that by a calmodulin inhibitor (W-7) and by inhibitors of protein kinase (H-7 and H-8). In a cell-free lysate of neutrophils, the NADPH-dependent production of O2- can be induced by sodium dodecyl sulfate (SDS). HA1077 at 100 microM had only a weak inhibitory effect on the cell-free, SDS-induced production of O2-, an indication that HA1077 inhibits the activation of NADPH oxidase, not the actual activity. The effects of H-7 and H-8 were similar to that of HA1077, whereas W-7 inhibited the production of O2- by the cell-free extract of HL-60 cells. This action of HA1077 could explain, in part, its ability to protect neuronal cells from death after ischemia.
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PMID:Inhibition by the protein kinase inhibitor HA1077 of the activation of NADPH oxidase in human neutrophils. 824 Apr

In a global model of brain ischemia, accumulation of amino acids was studied in the extracellular space of the auditory cortex and the internal capsule using microdialysis, and in CSF of halothane anesthetized cats. In both brain regions, blood flow determined by hydrogen clearance decreased below 10 ml/100 g/min after extracranial multiple-vessel occlusion, and extracellular potassium activity (Ke) measured in the dialysate increased significantly. A delayed rise in Ke was observed in CSF. In contrast, ischemic amino acid accumulation differed markedly between the two brain regions investigated. In cortex, transmitter amino acids glutamate, aspartate, and gamma-aminobutyric acid (GABA) rose almost immediately after onset of ischemia, and increased 30-, 25-, and 250-fold, respectively, after 2 h of ischemia. The nontransmitter amino acids taurine, alanine, and serine increased 10-, seven-, and fourfold, respectively, whereas glutamine and essential amino acids (valine, phenylalanine, isoleucine, and leucine) increased only 1.5-fold. In the internal capsule, increases in amino acids, if any, were delayed and much smaller than in cortex. The largest alteration was a fivefold elevation of GABA. In CSF, changes in amino acids were small and comparable to those in the internal capsule. Our results demonstrate that ischemia-induced extracellular amino acid accumulation is a well localized phenomenon restricted to gray matter structures that possess release and reuptake systems for these substances. We assume that amino acids diffuse slowly into adjacent while matter structures, and into CSF.
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PMID:Ischemia-induced accumulation of extracellular amino acids in cerebral cortex, white matter, and cerebrospinal fluid. 841 67

By studying early postmortem changes in cerebrospinal fluid (CSF) it is possible to draw conclusions as to premortem focal brain cell injury and terminal brain ischemia. Cisternal fluid (CF) from 40 different adult cadavers with no known neurological disorder was analyzed and compared with known in vivo values. They were divided into four groups (n = 10 in each group), CF samples taken 2, 4, 10, and 24 h after death. The enzyme activity of CK and CK-BB (EC 2.7.3.2) increased linearly and statistically significantly 4-24 h postmortem (P < 0.001) the 2 h values being already 10 to 20 times higher than in vivo, LD and its isoenzymes 1 to 3 (EC 1.1.1.27) distinctly 10 to 24 h after death. Glucose and pyruvate concentrations in the CF declined, as did Na+ and Cl-. Lactate and K+ increased over time. The earliest statistically significant changes between different timepoints were seen in lactate, pyruvate and K+ concentrations. The GABA concentration was already more than 170 times at 2 h postmortem, and glutamate more than 20 times higher than in vivo. The concentrations of alanine, glycine, lysine, histidine, isoleucine, phenylalanine, and tyrosine were 2 to 3 times higher at 2 h postmortem than during life. The concentrations of all amino acids and ammonia increased linearly and statistically significantly (P < 0.001) in the CF 4 to 24 h postmortem.
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PMID:Critical evaluation of postmortem changes in human autopsy cisternal fluid. Enzymes, electrolytes, acid-base balance, glucose and glycolysis, free amino acids and ammonia. Correlation to total brain ischemia. 851 12

We previously showed that generation of reactive oxygen species during myocardial ischemia and reperfusion stimulates cardiac sympathetic afferent nerve endings. We hypothesized that, in this feline model of brief ischemia and reperfusion, HO. is produced during ischemia and the rate and concentration of production of HO.during reperfusion is dependent on the duration of myocardial ischemia. Therefore, we evaluated the time dependency of production of HO. during reperfusion after 2, 5, and 10 min of reversible occlusion of the left anterior descending (LAD) coronary artery to induce ischemia in cats (n = 10). Blood samples collected from the coronary vein at 0.25, 1, 2, and 4 min after 2 min of ischemia revealed net cumulative rate of production of p-, m-, and o-tyrosine of 99 +/- 31, 10 +/- 5.1, and 0.8 +/- 0.2 nmol.min-1.g-1, respectively. After 5 min of ischemia, net cumulative rates of production of p-, m-, and o-tyrosine during reperfusion were 177 +/- 63, 74 +/- 26, and 1.6 +/- 0.8 nmol.min-1.g-1, respectively, whereas after 10 min of ischemia production rates were 153 +/- 42, 78 +/- 29, and 2.1 +/- 0.5 nmol.min-1.g-1, respectively. The highest rate of production of tyrosines was observed immediately after ischemia, perhaps indicating a washout of HO.-derived products that had accumulated in the myocardium during ischemia. To evaluate production of HO. during ischemia, deoxygenated saline (PO2 10 +/- 0.9 mmHg) containing phenylalanine was perfused into the ischemic coronary vascular bed through a cannula placed in the LAD (n = 16). Perfusate was collected from the coronary vein during the 10 min of ischemia. Net production of HO. during ischemia, measured by the production of p-, m-, and o-tyrosine, was 82 +/- 11, 6.6 +/- 0.4, and 1.7 +/- 0.3 nmol.min-1.g-1, respectively. Pretreatment with deferoxamine (10 mg/kg, n = 7) or dimethylthiourea (10 mg/kg, n = 6) decreased net production of HO. during ischemia and reperfusion. These results demonstrate that HO. is produced during brief ischemia and reperfusion, with the greatest amount being produced immediately after ischemia. Additionally, we show that the duration of brief ischemia determines the rate of production of HO. during reperfusion.
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PMID:Hydroxyl radical production during myocardial ischemia and reperfusion in cats. 877 Jan 9

Periods of ischemia followed by reperfusion of the ischemic tissue are associated with myocardial damage and ventricular arrhythmia. Angiotensin converting enzyme inhibitors limit the occurrence of these arrhythmias. The protective effects of angiotensin converting enzyme inhibitors may be due to inhibition of bradykinin (BK) degradation, rather than inhibition of angiotensin II formation. Other enzymes which catabolize BK include the endopeptidases EP24.11 and EP24.15. The purpose of this study was to determine if inhibitors of EP24.11 and EP24.15 decrease ischemia/reperfusion injury and if this protection is mediated by BK receptors. Rabbits were anesthetized and prepared for recording of cardiovascular parameters. The chest was opened and a left ventricular artery occluded for 30 min, followed by a 2-hr reperfusion period. Infarct size was determined using triphenyl tetrazolium chloride staining immediately after reperfusion. The enzyme inhibitors, ramiprilat, N-[1-(R,S)-carboxy-3-phenylpropyl]-Phe-pAB, and N[1-(R,S)-carboxy-3-phenylpropyl]-Ala-Ala-Phe-pAb, singly and in combinations were administered 3 min before reperfusion. Compared to saline (32.1 +/- 2.1), ramiprilat (18.3 +/- 2.8) and the EP inhibitors (14.4 +/- 1.4 for the combination) significantly decreased infarct size, with the greatest decrease occurring when all three inhibitors were combined (10.6 +/- 1.5). The protective effect of the EP inhibitors was blocked by the BK2 receptor antagonist, HOE 140 (30.1 +/- 2.6). Enzyme assays demonstrated EP24.11 and EP24.15 in the rabbit heart. We conclude that the EP inhibitors decreased ischemia/reperfusion injury by protecting BK from metabolism and that a combination of inhibitors provides superior protection to that given by a single agent.
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PMID:Endopeptidase inhibitors decrease myocardial ischemia/reperfusion injury in an in vivo rabbit model. 881 83

Neutrophil-derived oxygen radicals have been implicated in the pathogenesis of gastrointestinal disorders such as acute gastric mucosal injury induced by ischemia-reperfusion or by nonsteroidal antiinflammatory drugs (NSAIDs). The objectives of the present in vitro and clinical study were to determine whether omeprazole inhibits the production of toxic oxidants from neutrophils and to evaluate whether this drug affects intralysosomal pH. The respiratory burst of human neutrophils were was measured by luminol-dependent chemiluminescence (ChL) assay. The lysosomal pH of neutrophil was assessed by the fluorescence intensity ratio of phagocytized FITC-dextran using a digital-fluorescence video microscope. In vitro studies revealed that omeprazole (1-100 microM) dose dependently inhibited the ChL value of purified neutrophils that were elicited by FMLP (f-methionyl-leucyl-phenylalanine) or opsonized zymosan. Lysosomal pH was also increased in a dose-dependent manner by pretreatment with omeprazole. Healthy volunteers administered omeprazole, 40 mg/d for 7 d, showed a significant reduction in ChL values in peripheral neutrophils. These results suggest that omeprazole can inhibit the production of toxic oxidants by activated neutrophils. The action of omeprazole may be associated with a malfunction of lysosomal oxidant-producing enzymes due to an elevated intralysosomal pH.
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PMID:Omeprazole attenuates oxygen-derived free radical production from human neutrophils. 889 77

The normal vascular wall contains resident leukocytes, notably tissue macrophages (histiocytes) and mast cells, that confer a rapid, eicosanoid-dependent vasoconstrictor response to agonists typical of leukocytes, such as the complement-derived anaphylatoxin C5a or the formylated peptide f-Met-Leu-Phe (isolated organ methodology). The eicosanoid-dependent vasomotor response is even more intense in pathologies that involve leukocyte infiltration of the blood vessel wall, such as atherosclerosis and serum sickness in the rabbit. The leukocyte compartment of the blood vessel is the likely source of vasoactive mediators (eicosanoids, radicals, cytokines) of physiopathological importance, with possible application in cardiac ischemia, lupus nephritis, vasculitides, and graft rejection. This line of investigation may be compared to the discovery and characterization of endothelium-dependent vasomotor responses. However, the problem is experimentally more demanding: histological correlations, experiments based on leukocyte depletion, reconstitution, and enrichment are useful approaches to document this form of circulatory control.
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PMID:Evidence for vascular tone regulation by resident or infiltrating leukocytes. 893 61


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