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)

As part of a major clinical trial, sequential biopsies were taken from the margins of venous leg ulcers during their healing. The changing patterns of tissue architecture and extracellular matrix synthesis during healing were documented histologically and immunocytochemically. Initial biopsies were similar in appearance: prominent fibrin cuffs, variable inflammation, hemosiderin, and red blood cell extravasation. So called "fibrin cuffs" were highly organized structures composed of laminin, fibronectin, tenascin, and collagen as well as trapped leukocytes and fibrin. Fibronectin was absent from the ulcer tissue although collagen was abundant. Major histologic changes were observed after 2 weeks' pressure bandage therapy; hemosiderin, acute inflammation, and granulation tissue with the deposition of fibronectin had all increased and epithelial migration had commenced. Complete epithelialization was frequent by the fourth week of treatment, but the basement membrane was incomplete. At this time, hemosiderin and red blood cell extravasation had decreased and "fibrin cuffs" were virtually absent although chronic inflammation remained. The complex organization of the so-called "fibrin cuffs" may inhibit angiogenesis (but offer protection against increased venous pressure) in addition to their previously ascribed role in causing tissue ischemia.
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PMID:Sequential changes in histologic pattern and extracellular matrix deposition during the healing of chronic venous ulcers. 127 79

Granulocytes play an important role in increasing the infarct size after ischemia and reperfusion by the release of oxygen-derived free radicals (ODFR) and lysosomal enzymes. It has been shown that the number of granulocytes adhering to the vascular endothelium increases after occlusion of the coronary artery, and that the area of myocardial damage can be reduced by preventing granulocyte adherence with monoclonal antibodies directed against adhesion receptors. The underlying mechanism of granulocyte activation under these conditions is not yet known. We have investigated whether granulocytes can be activated directly by reduced oxygen tensions. Granulocytes were suspended in a hypoxic buffer and incubated on fibronectin and gelatin coated microtitre plates at 1-3% ambient oxygen to study their ability to adhere to these matrices. The results showed that the adherence of granulocytes to fibronectin was dependent on the duration of hypoxia. After 30 min of incubation under hypoxia granulocyte adherence increased 1.3 to 1.8 fold compared to the normoxic control. The adherence to fibronectin could be inhibited partially by anti-CD18 antibody, a monoclonal antibody to the common beta chain of a class of extracellular matrix receptors. This direct activation of granulocytes due to hypoxic conditions may have implications for the interaction of these cells with the vascular endothelium in vivo.
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PMID:Studies on the interaction of leucocytes and the myocardial vasculature. I. Effect of hypoxia on the adherence of blood granulocytes. 136 46

Plasma fibronectin (pFn) stimulates macrophage phagocytosis of tissue debris; pFn deposition in tissues may influence vascular integrity. Although the acute depletion of pFn after surgery and/or injury has been described, less attention has been given to the rebound hyperfibronectinemia presumably "triggered" by the early pFn depletion. Using a model that compartmentalized the site of tissue injury and thus attenuated the initial pFn depletion, we studied this rebound elevation of pFn in anesthetized rats (250-350 g) after the surgical trauma of groin dissection alone (sham group) or surgery coupled with 4 h of hindlimb ischemia (experimental group). Nonoperated control rats were also anesthetized. Shams had baseline (preoperative) 6-, 8-, and 22-h postoperative pFn levels of 573 +/- 61, 598 +/- 62, 695 +/- 57, and 929 +/- 87 micrograms/ml, respectively. In the surgery-ischemia group, pFn also elevated to 1,117 +/- 40 micrograms/ml at 22 h postsurgery. Nonoperated control rats (only anesthetized) had no elevation of pFn. Intravenous infusion of gelatin-coated lipid particles (50 mg/100 g) depleted pFn by 89.3% but was unable to prevent the rebound elevation of pFn. The blood clearance of 125I-labeled pFn was very similar in control, sham, and experimental rats. In contrast, pFn synthesis over the 22-h period was dramatically altered and equal to 2.12 +/- 0.16, 3.40 +/- 0.56, and 4.49 +/- 0.17 mg pFn synthesized/100 g body wt, in control, sham, and experimental rats respectively. Thus a rapid increase in pFn synthesis contributes to the rebound hyperfibronectinemia after sublethal surgical injury.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Rebound elevation of fibronectin after tissue injury and ischemia: role of fibronectin synthesis. 141 4

Liver and spleen phagocytic clearance of blood-borne microparticulate tissue debris and products of intravascular coagulation after trauma and surgical injury is an important mechanism to limit the deposition of debris in the pulmonary vascular bed. Plasma fibronectin (pFn) modulates this clearance process. We evaluated the effect of a localized peripheral ischemia and reperfusion injury on liver and spleen phagocytic function. Male rats (250 to 350 g) underwent 4 hours of tourniquet-induced bilateral hindlimb ischemia, followed by 18 hours of reperfusion after release of the tourniquet. Rats subjected to ether anesthesia alone or anesthesia followed by groin incision without ischemia were the control and sham groups, respectively. Reticuloendothelial (RE) phagocytic function was assessed at 15 minutes and 18 hours after the start of reperfusion by the in vivo liver and spleen removal of blood-borne iodine 125 (125I)-test microparticles, which were coated with gelatin (denatured collagen) to enhance their interaction with pFn. Liver and spleen particle uptake in control and sham rats was similar. In contrast, after 4 hours of ischemic injury with 15 minutes of reperfusion, we observed a 30% to 40% decrease (p less than 0.05) in liver and spleen particle uptake as compared with sham controls with partial restoration of this removal mechanism by 18 hours. This depression in liver and spleen phagocytic function was associated with a significant (p less than 0.05) increase in the deposition of the 125I-test particles in the lung. RE depression was not due to a deficiency of pFn; indeed, a marked elevation (588 +/- 12 micrograms/mL versus 1,083 +/- 40 micrograms/mL) of pFn was observed by immunoassay over the 18-hour reperfusion interval. Comparative bioassay of humoral (opsonic) versus cellular (Kupffer's cell) activity revealed that Kupffer's cells in livers from controls or ischemia-reperfusion rats exhibited normal phagocytic function when incubated in plasma harvested from either control or 4-hour ischemic rats. The opsonic activity of plasma harvested after ischemia and reperfusion was also more than adequate, consistent with the immunoassay analysis. Thus, the impaired liver and spleen clearance mechanism after peripheral ischemia and reperfusion injury did not appear to be due to either a macrophage cellular deficit or a lack of pFn. This clearance depression may be mediated by splanchnic malperfusion, which is known to develop after peripheral ischemia and reperfusion and associated soft tissue injury.
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PMID:Liver and spleen phagocytic depression after peripheral ischemia and reperfusion. 141 24

Lyophilized type I collagen (L.C.) can stimulate wound healing by recruiting a number of different cell types (i.e. platelets and macrophages) and proteins (i.e. fibronectin). Platelets and macrophages produce locally-acting growth factors that in turn induce fibroblast and epidermal migration, angiogenesis and increase matrix synthesis. Chronic leg ulcers (C.L.U.) are the end result of microvascular failure owing to ischemia and stasis. When L.C. has been used in the treatment of C.L.U. we have observed that: a) it is significantly more effective in stimulating the healing of chronic venous ulcers when compared to hydrocolloids (p less than .05), the two products being applied upon half of the same ulcer; b) in the treatment of C.L.U. due to arterial obstruction L.C. is more effective than hydrocolloids without achieving statistical significance; c) it is very effective in the treatment of C.L.U. in thalassaemic patients; d) telethermographic studies have demonstrated an increase of blood perfusion and histological studies have shown the stimulation of angiogenesis, fibropoiesis and epidermal growth; e) the application of L.C. determines the maximum obtainable increase also under conditions of proven cicatrization difficulty; and f) enzymatic degradation of L.C. has not promoted any bacterial infection and no local or generalized sensibilization phenomena have been observed. We can conclude that L.C. is a pharmacological approach to wound healing, directly interfering with cellular and non-cellular components, and significantly improves the reparative process when delayed.
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PMID:Lyophilized type-I collagen and chronic leg ulcers. 172 86

Exposure of the vessel wall to hypoxemia is a central feature of ischemic cardiovascular disease. This led us to examine the perturbation of endothelial cell properties under hypoxia. An atmosphere of pO2 of 12 mmHg is not lethal to the endothelial cells for up to five days, but barrier function was impaired. Increased passage of macromolecule tracers were observed in time- and dose-dependent manner and electron microscopy demonstrated small gaps (0.5-1.0 micron) between cells. Expression of the anticoagulant cofactor thrombomodulin was also perturbed: thrombomodulin activity and antigen decreased in parallel. Northern blots showed almost complete suppression of thrombomodulin in hypoxic culture. Furthermore, synthesis of other proteins, such as fibronectin, was slightly enhanced under hypoxia. In addition to the suppression of these anticoagulant cofactor, hypoxic endothelial cell displayed a noval procoagulant activity distinct from tissue factor. Further study revealed that hypoxic endothelial cultures directly activated Factor X, as assessed by functional assays and SDS-PAGE. In addition to this no activation of Factor IX or prothrombin was observed. The hypoxia-induced Factor X activator was membrane-associated, required calcium to form Factor Xa, was inhibited by HgCl2 but not by PMSF, and had Km approximately 25 micrograms/ml. Co-incubation of hypoxic cultures with cycloheximide prevented the expression of this activity, suggesting that protein synthesis is required for its expression. These functional perturbations of endothelial cells were reversible following reoxygenation. These data indicate that hypoxia imposes a selective perturbation on endothelial cell function, suggesting the possible contribution of hypoxemia to vascular dysfunction in ischemia.
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PMID:Modulation of endothelial function by hypoxia: perturbation of barrier and anticoagulant function, and induction of a novel factor X activator. 196 56

Various substances (saline solution, dextran, heparin, proteinase inhibitors, etc.) have been investigated to determine their influence on adhesion prevention, but until recently the results were controversial and lacked any implication for clinical use. The analysis of intraperitoneal plasminogen activating factor (PAA) and the fibronectin production rate of peritoneal macrophages promises new aspects of adhesion formation and prevention. The results of studies show a close correlation between ischemia/infection and the decrease of PAA as well as increased adhesion formation in patients (endometriosis) with increased fibronectin production by peritoneal macrophages.
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PMID:[Prevention of adhesions by intraperitoneal administration of substances in abdominal interventions]. 198 79

Only 50% of rabbits survive 90 min hepatic ischemia in spite of decompression of the gut. The remainder die within 36 h after operation. A single application of fibronectin before hepatic ischemia delays death for only a few hours. However, three postischemic applications of fibronectin--immediately after operation and 5 h and 24 h later--are associated with a statistically significant rise in the survival rate. Analysis of the transaminases indicates that fibronectin obviously limits the extent of ischemic liver cell necrosis. Of major significance is the fact that fibronectin supplement enables the RES of the liver to improve its phagocytic capacity, as shown by the RES clearance test. The presented experimental model shows that the liver with its RES, located between the splanchnic and the systemic circulation, is of particular significance for the entire organism. Hepatic ischemia or shock, independent of the initial cause, leads to significant reduction of hepatic phagocytosis. The results indicate that substitution of opsonins supports the phagocytic capacity.
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PMID:Protective effect of fibronectin in temporary liver ischemia: an experimental study. 356 Jul 82

Patients with coronary heart disease and angina pectoris were examined. The blood outflowing from the myocardium at the height of ischemia induced by atrial stimulation was found to have lower levels of fibronectin. Ten minutes after the stimulation discontinuation the concentration of fibronectin returned to baseline. A reduction in the fibronectin content during myocardial ischemia seems to be related to its consumption as a result of maintaining antithrombotic function.
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PMID:[Fibronectin level in coronary sinus blood in myocardial ischemia caused by atrial stimulation]. 652 Nov 78

The extracellular matrix plays an important role in biological processes, for example cellular adhesion, proliferation, migration and differentiation. Many of the cell-cell and cell-matrix interactions are mediated by extracellular matrix components and by their respective membrane receptors. Important pathophysiological processes occur through these interactions of which ontogenesis tissue differentiation and reconstruction, many inflammatory and immunological events and metastatic processes and invasion. The myocardium is made of muscular, vascular and connective components that exist in a state of equilibrium based on their relative proportions, integral structures, and on their physical and chemical characteristics. The Authors have described molecular events that lead to the organization of the cardiac tissue in physiological conditions and to its reorganization in pathological situation. Furthermore they have evaluated the role of fibronectin, a glycoprotein of the extracellular matrix in the initial phase of cardiac ischemia.
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PMID:[Anatomical and functional characteristics of the myocardial interstitial space]. 763 98


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