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

Derivatives of arachidonic acid have been found to play a role in the reperfusion injury of various tissues. These compounds have a broad spectrum of activity, including modulation of white blood cell response to injured tissue. This study was designed to determine the effect of thromboxane and lipoxygenase derivatives on the local and systemic response to ischemia and reperfusion of skeletal muscle. Fifteen dogs were separated into three groups and subjected to gracilis muscle ischemia followed by 2 hours of reperfusion. One group served as controls, one group was treated with OKY-046 (a thromboxane synthetase inhibitor), and one group was treated with diethylcarbamazine (a lipoxygenase inhibitor). White blood cell activation as measured by superoxide anion production, and eicosanoid levels were measured both in the gracilis venous effluent and central venous circulation. These results were compared to infarct size in the gracilis muscle. OKY-046 significantly reduced thromboxane production in both the central venous (102 +/- 30 to 31 +/- 9 pg/ml, p less than 0.05) and gracilis samples (107 +/- 22 to 25 +/- 6 pg/ml, p less than 0.005). This was accompanied by a reduced white cell activation in the central venous blood (15 +/- 1 to 10 +/- 1 nmol O2-, p less than 0.05), but did not affect infarct size or white cell activation in the gracilis. Conversely, diethylcarbamazine significantly reduced both white cell activation (16 +/- 1 to 10 +/- 1 nmol O2-, p less than 0.005) and infarct size in the gracilis muscles (61.6% +/- 4.5% to 28.5% +/- 8.6%, p less than 0.01), as well as reduced systemic white blood cell activation.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The influence of arachidonic acid metabolites on leukocyte activation and skeletal muscle injury after ischemia and reperfusion. 165 4

The objective of this study was to explain why the normally observed reactive hyperemia in frog sartorius muscle following ischemia is absent when this muscle atrophies. Two possibilities were addressed: (1) absence is due to lowered O2 consumption, making the muscle more tolerant to ischemia, and (2) absence is linked to impaired vascular function in atrophy. We used 10 frogs after 2-3 months and 8 frogs after 7-14 months of laboratory captivity. Animals in the latter group had a significantly lower sartorius muscle weight, i.e., 85 +/- 33 vs 24 +/- 11 SD mg. Using intravital video microscopy, we measured red cell velocity in capillaries at the muscle surface, and densities of capillaries with moving (NCPER) and stationary red cells (NCSTAT) before and after 30 min ischemia. Ischemia induced a significant temporary increase in overall velocity (from 0.10 to 0.27 mm/sec) in normal muscles, but no increase in atrophied muscles. It resulted in no difference in NCPER between the two groups (preischemic levels in both groups: 15.0 cap/mm of test line), but in a significant difference in NCSTAT (3.8 vs 11.5 cap/mm in atrophy). Using light and electron microscopy, we also measured structural and ultrastructural parameters in both groups. In atrophied muscles the mean fiber cross-sectional area was lower (568 vs 1935 microns 2) and anatomical capillary density higher (892 vs 282 cap/mm2) than in normal muscles. Mitochondrial volume density was not statistically different from the 1.5% level in the normal muscle, while the lipid droplet volume density was larger (2.33 vs 0.58%). The percentage of capillaries with damaged endothelium was larger (33.5 vs 12.6%). Using histology, the white cell volume density per capillary volume was also found to be larger in atrophy (1.96 vs 0.83%). From the discrepancy between the lack of intergroup difference in preischemic NCPER and the 3.2-fold difference in anatomical capillary density we estimate that about 60% of capillaries were perfused with red cells in atrophied muscles. Although the preischemic rate of perfusion in these capillaries was comparable between the two groups, the postischemic response was not: reactive hyperemia was absent in atrophy. Our mitochondrial and lipid volume density data do not support the possibility that this absence was due to lowered O2 consumption, as these densities did not decrease with atrophy.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Microvascular response to ischemia, and tissue structure, in normal and atrophied skeletal muscle. 235 92

Neutrophilic leukocytes have been implicated as important mediators of ischemic myocardial injury. We investigated the role of neutrophils in skeletal muscle ischemia/reperfusion injury by using the rat hindlimb ischemia model. We rendered Wistar rats neutropenic by administering 750 rad of whole-body radiation (mean white blood cell count, 300 +/- 50/mm3; 3 days after radiation). In anesthetized rats (10 neutropenic and 10 control), 3 hours of ischemia were induced in one hindlimb by application of a tourniquet to the proximal thigh; the contralateral limb served as an internal, nonischemic control. After 1 hour of reperfusion the gastrocnemius and soleus muscles were excised bilaterally and evaluated for ischemic injury by means of a quantitative spectrophotometric assay of triphenyltetrazolium chloride (TTC) reduction. In control rats the reduction of TTC by ischemic muscle averaged 27.0% +/- 7.3% of that by nonischemic muscle; whereas in neutropenic rats the value for ischemic muscle was 65.4 +/- 11.6% (p less than 0.05). To determine if the contribution of the neutrophils to ischemic injury is due to oxygen-derived free radical formation, an additional 10 animals were infused with 5000 units of super-oxide dismutase and 10,000 units of catalase at the time reperfusion was restored. After treatment with free radical scavengers, TTC reduction by ischemic limbs was 25.5% +/- 7.0% of that by nonischemic limbs and did not differ from that in control animals (p greater than 0.05). The results show a protective effect of neutropenia and suggest a significant role of the white cell in the pathophysiology of ischemic skeletal muscle injury.
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PMID:The role of leukocytes in the pathophysiology of skeletal muscle ischemic injury. 247 24

Pulmonary artery obstruction results in minimal parenchymal abnormalities in normal lung and diminishes edema formation in dog lungs injured by oleic acid. We tested the hypothesis that reperfusion of ischemic regions would result in significant injury in normal lung and would ablate the protective effect of ischemia in oleic acid injury. The pulmonary artery of the left diaphragmatic lobe was occluded for 48 h in 12 oleic-acid-injured and 10 normal animals. Observations made immediately before reperfusion and for 4 h after reperfusion in the awake dogs indicated that reperfusion resulted in systemic abnormalities in both groups of animals, including a rise in temperature, a fall in cardiac output, and a marked drop in circulating leukocytes. In uninjured animals, the reperfused lobe demonstrated an elevated wet-to-dry weight ratio of 5.70 +/- 0.13 compared with 4.42 +/- 0.06 for the right diaphragmatic lobe (p less than 0.05). Histologic examination revealed edema and white cell infiltrates in the alveoli of the reperfused lobe in uninjured animals. In injured animals, there was no difference in either wet-to-dry ratios or morphologic aspects between the lobes. The results demonstrate both a local and systemic toxic effect of reperfusion in normal animals and ablation of the partial protective effect of pulmonary artery occlusion in oleic-acid-injured animals.
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PMID:Reperfusion of ischemic dog lung results in fever, leukopenia, and lung edema. 376 30

Eighteen patients with recent ischemic stroke were compared with an equal number of matched controls. Standardized suspensions of red cells as well as of red and white cells were filtered in a new filtration apparatus capable of discriminating between cell deformability and filter occlusion. Results show that red cell deformability, although slightly lower than in controls, is not significantly altered in stroke patients. Filter occlusion, however, was significantly higher in patients when red and white cell suspensions were filtered, but not when red cell suspensions were used, suggesting that white cell filterability is impaired after stroke, which could be due to decreased deformability and/or increased adhesiveness of leukocytes. Slowed white cell passage may also occur in the living microcirculation and may present an obstacle to nutritive flow in exchange vessels, possibly contributing to local ischemia and tissue necrosis after stroke.
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PMID:Leukocyte rheology in recent stroke. 381 Jul 70

We evaluated the effect of antibodies directed against a leukocyte adhesion molecule (ICAM-1) in an embolic model of stroke followed by thrombolysis with tissue plasminogen activator (tPA). To test whether reperfusion injury after ischemia was related to white cell adhesion, microclots were injected into carotid circulation. The conditions examined were control, alpha-ICAM 5 min following ischemia, tPA 30 min after ischemia, and the combination of alpha-ICAM and tPA. alpha-ICAM and tPA both increased the amount of clot necessary to produce permanent neurological damage. Combined therapy was no more effective than either substance alone. A similar outcome was obtained when tPA was delayed until 90 min postischemia. When thrombolysis was delayed 3 h following embolism, neither tPA nor the tPA/alpha-ICAM combination reduced neurological damage. Thus, the alpha-ICAM antibody and tPA each effectively reduced neurological damage but the interaction was not significant.
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PMID:Monoclonal antibody to the ICAM-1 adhesion site reduces neurological damage in a rabbit cerebral embolism stroke model. 809 42

Neutrophil accumulation and activation within the myocardium during ischemia and reperfusion has been shown to play a prominent role in the development of myocardial stunning and infarction. To determine if a simple inhibitor of neutrophil adhesion could reduce myocardial infarct size, we administered NPC 15669 (a new antiinflammatory agent that inhibits neutrophil adhesion) to 12 pigs (6 controls, 6 NPC-treated) in a porcine model of ischemia and reperfusion injury. Each animal received a continuous infusion of either NPC (10 mg/kg intravenous bolus followed by 6 mg.kg-1 x h-1 intravenous infusion) or an equal volume of normal saline solution during 1 hour of left anterior descending artery occlusion and 2 hours of reperfusion. There were no significant differences in the pre-ischemia, mid-ischemia, or postischemia rate-pressure product between control and experimental groups. The regions at risk were similar in both groups. However, the mean myocardial infarct size was reduced by 51% with administration of NPC 15669 (30.7% +/- 6.8%) compared with controls (62.3% +/- 5.4%; p < 0.01). These data indicate that NPC 15669, an inhibitor of neutrophil adhesion, substantially reduces myocardial infarct size after transient left anterior descending artery occlusion and that adhesion of the white cell to vascular endothelium may be an important element of the pathogenesis of myocardial infarction.
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PMID:Inhibition of neutrophil adhesion reduces myocardial infarct size. 823 1

In order to further elucidate the possible contribution of leukocytes to microvascular injury during reperfusion following total hepatic ischemia, we studied the spatial relationship between areas of white cell accumulation and areas of microvascular damage in the rat liver in vivo. No-flow hepatic ischemia was produced for 90 min in vivo and during the ensuing reperfusion phase (I/R) leukocyte accumulation, absolute number of perfused sinusoids per unit area, and red blood cell velocity were quantitated using in vivo epi-fluorescence video microscopy. The total number of stationary leukocytes in the liver during reperfusion was found to be significantly elevated following ischemia compared to time-matched sham-operated controls. In addition, by 2 hr of reperfusion, approximately 80% of the leukocytes in the I/R group were extravascular compared to only about 50% in the controls. When leukocyte accumulation and microhemodynamics were expressed on the basis of whole liver, the increased accumulation of leukocytes was associated with decreased microvascular perfusion as indicated by decreased number of sinusoids perfused and decreased red blood cell velocity. However, when the data were analyzed on the basis of .05mm2 microscopic fields on the surface of the liver, there was no difference in leukocyte accumulation in areas with sinusoidal blood flow compared to areas that were devoid of perfused sinusoids. Moreover, in a correlation analysis of number of adherent leukocytes/microscopic field vs red blood cell velocity in perfused sinusoids in that field, only a very small negative correlation between leukocytes/field and red blood cell velocity was found (r = -.23, p < .05). These results demonstrate that at the whole organ level leukocyte accumulation appears to correlate well with microvascular damage; however, this increase in whole liver accumulation of leukocytes does not necessarily reflect accumulation at sites of overt microvascular damage. Thus, leukocyte-independent factors are likely to be of considerable quantitative importance in microvascular injury during reperfusion following hepatic ischemia.
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PMID:Spatial relationship between leukocyte accumulation and microvascular injury during reperfusion following hepatic ischemia. 847 69

We briefly summarize our findings on alterations in capillary structure in skeletal muscle and heart in response to up to 30 min of ischemia. In frog sartorius muscle, reactive hyperemia was absent in atrophy. Increased spatial heterogeneity of red cell velocity in individual capillaries was observed, as were increases in the percentage of capillaries with damaged endothelium and white cell volume density in capillaries. Examination of the effect of aging on the response of the vascular bed to 30 min ischemia in extensor digitorum longus muscle of Fisher 344 rats suggested that the lack of postischemic hyperemia and structural alterations in frog muscle were related to disuse rather than aging per se. However, the specific study of disuse in rat extensor digitorum longus muscle after chronic application of tetrodotoxin revealed both capillary damage and a postischemic hyperemic response. It suggested an effect of the degree of tissue deterioration on the hyperemic response after short-term disuse in rat muscle, compared to longer-term atrophy in frog. Morphometric data in isolated rabbit heart suggested a link between microvascular compression as a result of tissue edema and decreased perfusion after 30 min total ischemia.
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PMID:Capillary ultrastructure and functional capillary density. 885 20

We investigated the long-term efficacy and the contraindications of single-session percutaneous ethanol injection (PEI) under general anesthesia in hepatocellular carcinoma (HCC). One hundred patients were treated from October, 1991, to April, 1996: 24 patients had a single capsulated HCC, 4.5 to 10 cm phi (group A); 62 had a single infiltrating tumor or multiple lesions (3 to 6), with 10 cm maximum phi (group B); 14 patients were in an advanced stage because of Child class C or of infiltrating tumors with portal thrombosis, with 14 cm lesion maximum phi (group C). Group A patients were treated because they were not operable or refused surgery. Three to 22 injections were performed (mean: 13) depending on tumor size and ethanol spread. The maximum injected volume of ethanol was 190 ml (mean: 57 ml). The procedure took 20 to 50 minutes (mean: 30 minutes). The mean hospital stay was 3.5 days. Tumor necrosis was complete in 58% of encapsulated tumors and > 70% in infiltrating lesions. The greatest lesion with complete post-PEI necrosis was 8.2 cm phi. A transient and variable increase in transaminase, bilirubin, white cell and D-dimer levels and a decrease in red cell, platelet, hemoglobin, fibrinogen and haptoglobin levels were observed. These changes were due to hepatic cell necrosis, hemolysis and focal thrombosis. One death (bleeding esophageal varices in the Child C patient)(1%) and four major complications (one peritoneal bleeding, one liver decompensation, two chemical segmentectomies with pain)(4%) were observed. 1, 2, 3 year survival rates for groups A, B and C were: 80, 63, 63%; 70, 50, 30% and 58, 14 and 0% respectively. In our experience, PEI was an efficacious procedure. The risk conditions are: superficial lesion site with severe coagulation defects, severe portal and/or pulmonary hypertension, esophageal varices at risk of bleeding, cardiac ischemia, advanced cirrhosis.
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PMID:[Single-session alcohol administration for hepatocarcinoma]. 942 44


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