Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P00750 (PLA)
 16,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The role of fibrinolytic system components in thrombus formation and removal in vivo was investigated in groups of six mice deficient in urokinase-type plasminogen activator (u-PA), tissue-type plasminogen activator (t-PA), or plasminogen activator inhibitor-1 (PAI-1) (u-PA-/-, t-PA-/- or PAI-1-/-, respectively) or of their wild type controls (u-PA+/+, t-PA+/+ or PAI-1+/+). Thrombus was induced in the murine carotid artery by endothelial injury using the photochemical reaction between rose bengal and green light (540 nm). Blood flow was continuously monitored for 90 min on day 0 and for 20 min on days 1, 2 and 3. The times to occlusion after the initiation of endothelial injury in u-PA+/+, t-PA+/+ or PAI-1+/+ mice were 9.4+/-1.3, 9.8+/-1.1 or 9.7+/-1.6 min, respectively. u-PA-/- and t-PA-/- mice were indistinguishable from controls, whereas that of PAI-1-/- mice were significantly prolonged (1 8.4+/-3.7 min). Occlusion persisted for the initial 90 min observation period in 10 of 18 wild type mice and was followed by cyclic reflow and reocclusion in the remaining 8 mice. At day 1, persistent occlusion was observed in 1 wild type mouse, 8 mice had cyclic reflow and reocclusion and 9 mice had persistent reflow. At day 2, all injured arteries had persistent reflow. Persistent occlusion for 90 min on day 0 was observed in 3 u-PA-/-, in all t-PA-/- mice at day 1 and in 2 of the t-PA-/-mice at day 2 (p <0.01 versus wild type mice). Persistent patency was observed in all PAI-1-/- mice at day 1 and in 5 of the 6 u-PA-/- mice at day 2 (both p <0.05 versus wild type mice). In conclusion, t-PA increases the rate of clot lysis after endothelial injury, PAI-1 reduces the time to occlusion and delays clot lysis, whereas u-PA has little effect on thrombus formation and spontaneous lysis.
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PMID:Differential role of components of the fibrinolytic system in the formation and removal of thrombus induced by endothelial injury. 1023 47

Thrombus formation at the site of atherosclerotic lesions, especially on a ruptured plaque, plays a central role in the "atherothrombosis" hypothesis. An activation of the hemostasis and a disturbed fibrinolysis are known. These alterations are especially marked in patients with acute coronary syndromes. In stable coronary artery disease, fibrinogen is elevated. Furthermore, minor alterations of the contact phase factor VII and consecutively of the thrombin system are detectable depending on the study population. Thrombin generation and activation become marked in patients with unstable angina pectoris or acute myocardial infarction. Possible reasons for this activation are an activation of the contact phase factor XII system and the release of tissue factor both from the ruptured plaque and from stimulated monocytes. The fibrinolytic system is markedly altered already in patients with stable coronary heart disease. Increased levels of tissue-type plasminogen activator and of urokinase-type plasminogen activator/receptor are measurable in atheromas. Tissue-type plasminogen activator mass concentration is systemically elevated already at early stages of atherosclerosis. Especially in patients with increased risk for acute coronary syndromes, the plasminogen activator inhibitor activity is significantly increased. Furthermore, a hypercoagulative state with increased d-dimer levels and plasmin-antiplasmin complexes can be measured. The alterations of hemostasis and especially of fibrinolysis are detectable for prolonged time period and persist much longer than the clinical symptoms of the patients. The increased plasminogen activator inhibitor activity is associated with the metabolic syndrome and constitutes an (in part genetically determined) disturbance in patients with stable or unstable coronary heart disease. However, the large intra- und interobserver as well as diurnal variability of this marker limits its use as a routine measure for risk stratification in patients. Alterations of the hemostasis and disturbances of fibrinolysis are detectable during the chronic as well as the acute phase of atherosclerosis. These changes are best documented for coronary heart disease, whereas less data are available for other manifestations of atherosclerosis. The use of newly developed molecular markers for single reaction steps of pathways instead of global functional tests and of new molecular biological methods did considerably improve the detailed knowledge on the pathomechanisms of the development of atherosclerosis, making the development of targeted therapies, e.g., against receptors possible. Future studies will investigate the quantitative impact of the various activated pathways (cause or reaction) and the effects of interventions on these pathomechanisms in patients with acute coronary syndromes. Studies will have to focus especially on the meaning of polymorphisms, early changes in the development of atherosclerosis and interactions with inflammatory processes.
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PMID:[Blood coagulation and fibrinolysis in arteriosclerosis]. 1041 53

Increased fibrinolytic activity and consumption coagulopathy are common consequences of liver transplantation and are a major cause of morbidity and death. In the present investigation the effects of hepatic ischemia on the coagulation mechanism were studied in the stump-tail monkey. The results suggest that, although fibrinolytic activity is induced by both major intraabdominal operations as well as one hour of hepatic ischemia, consumption coagulopathy, presumably due to intravascular clotting, is enhanced by the revascularization of the ischemic liver, possibly because of clotting within the liver itself. Release of a plasminogen activator from the liver due to hepatic ischemia alone is not demonstrated by these studies. It is believed that the first phase of intravascular coagulation after liver transplantation is due to release of tissue activators from vascular endothelium, which may be minimized by the action of ganglionic blocking agents. The severity of fibrinolysis in this stage is aggravated by the "liverless state," in which no clearance of plasminogen activators occurs. The degree of liver injury directly affects the ability of the liver to control hypercoagulability in the second phase. Thrombus formation which we believe occurs during this phase may be minimized by use of continuous controlled heparinization.
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PMID:Effects of hepatic ischemia on coagulation in primates. Application to liver transplantation. 1048 79

Using tracings of (125)I-labeled fibrin(ogen) in rodents, we examined the hypothesis that platelets impede the lysis of pulmonary emboli. (125)I-Microemboli (ME, 3-10 micron diameter) lodged homogeneously throughout the lungs after intravenous injection in both rats and mice (60% of injected dose), caused no lethality, and underwent spontaneous dissolution (50 and 100% within 1 and 5 h, respectively). Although lung homogenates displayed the most intense fibrinolytic activity of all the major organs, dissolution of ME was much slower in isolated perfused lungs (IPL) than was observed in vivo. Addition of rat plasma to the perfusate facilitated ME dissolution in IPL to a greater extent than did addition of tissue-type plasminogen activator alone, suggesting that permeation of the clot by plasminogen is the rate-limited step in lysis. Platelet-containing ME injected in rats lysed much more slowly than did ME formed from fibrin alone. (125)I-Thrombi, formed in the pulmonary vasculature of mice in response to intravascular activation of platelets by injection of collagen and epinephrine, were essentially resistant to spontaneous dissolution. Moreover, injection of the antiplatelet glycoprotein IIb/IIIa antibody 7E3 F(ab')(2) facilitated spontaneous dissolution of pulmonary ME and augmented fibrinolysis by a marginally effective dose of Retavase (10 microg/kg) in rats. These studies show that platelets suppress pulmonary fibrinolysis. The mechanism(s) by which platelets stabilize ME and utility of platelet inhibitors to facilitate their dissolution deserves further study.
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PMID:Platelets inhibit the lysis of pulmonary microemboli. 1183 49

The etiologic role of thrombotic and fibrinolytic disorders in Perthes' disease has not been determined. A case control study was conducted to determine whether thrombotic and fibrinolytic disorders are associated with Perthes' disease. Twenty-six patients with Perthes' disease were matched with 26 control patients for gender, age (2-year range), and time of presentation (1-year range). Thrombotic disorders were investigated for protein C activity, protein S activity, antithrombin III, anticardiolipin antibody immunoglobulins G and M, and lupus anticoagulant. Fibrinolytic disorders were investigated for tissue-plasminogen activator, plasminogen activator inhibitor-1, plasminogen activator inhibitor-1 to tissue plasminogen activator ratio, lipoprotein (a), and plasminogen. The activity of protein C, which suppresses factor Va and leads to an increase of coagulant activity when decreased, was increased in patients. There were no significant differences in the levels of other factors between the patients and controls. No evidence was found to prove a relationship between Perthes' disease and thrombotic or fibrinolytic disorders in the patients in the current study.
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PMID:Role of thrombotic and fibrinolytic disorders in the etiology of Perthes' disease. 1201 5

Thrombus formation and degradation is partly due to a complex interplay between tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor 1 (PAI-1). There is accumulating evidence that plasma levels of t-PA and PAI-1 may be influenced by an interaction between the fibrinolytic and renin-angiotensin systems. The goal of this study was to conduct an exploratory data analysis to determine whether there is evidence that the relationship (i.e. correlation) between plasma t-PA and PAI-1 is influenced by interactive effects of the angiotensin converting enzyme (ACE) insertion/deletion (I/D) and plasminogen activator inhibitor 1 (PAI-1) 4G/5G polymorphisms in a sample of 50 unrelated African Americans and 117 unrelated Caucasians. In a single-locus analysis, no evidence for heterogeneity of plasma t-PA and PAI-1 correlations among either ACE I/D or PAI-1 4G/5G genotypes was detected. However, using the combinatorial partitioning method for exploratory data analysis, we identified evidence that is suggestive of heterogeneity of plasma t-PA and PAI-1 correlations among multilocus ACE I/D and PAI-1 4G/5G genotypes in African American females, Caucasian females, Caucasian males, but not African American males. From these results, we propose as a working hypothesis that the correlation between plasma t-PA and PAI-1 may be dependent on epistatic effects of the ACE I/D and PAI-1 4G/5G polymorphisms. This study supports the idea that interactions between the fibrinolytic and renin-angiotensin systems play an important role in the genetic architecture of plasma t-PA and PAI-1.
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PMID:The relationship between plasma t-PA and PAI-1 levels is dependent on epistatic effects of the ACE I/D and PAI-1 4G/5G polymorphisms. 1212 88

The authors evaluated the therapeutic efficacy of tacrolimus (FK506), administered alone or in combination with recombinant tissue plasminogen activator (t-PA), on brain infarction following thrombotic middle cerebral artery (MCA) occlusion. Thrombotic occlusion of the MCA was induced by a photochemical reaction between rose bengal and green light in Sprague-Dawley rats, and the volume of ischemic brain damage was determined 24 hours later. Intravenous administration of tacrolimus or t-PA dose-dependently reduced the volume of ischemic brain infarction, whether administered immediately or 1 hour after MCA occlusion. When tacrolimus or t-PA was administered 2 hours after MCA occlusion, each drug showed a tendency to reduce ischemic brain damage. However, combined treatment with both drugs resulted in a significant reduction in ischemic brain damage. On administration 3 hours after MCA occlusion, tacrolimus alone showed no effect, and t-PA tended to worsen ischemic brain damage. However, the combined treatment with both drugs not only ameliorated the worsening trend seen with t-PA alone, but also tended to reduce ischemic brain damage. In conclusion, tacrolimus, used in combination with t-PA, augmented therapeutic efficacy on brain damage associated with focal ischemia and extended the therapeutic time window compared to single-drug treatments.
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PMID:A combined treatment with tacrolimus (FK506) and recombinant tissue plasminogen activator for thrombotic focal cerebral ischemia in rats: increased neuroprotective efficacy and extended therapeutic time window. 1236 59

Thrombus formation after rupture of an atherosclerotic plaque plays a crucial role in coronary artery disease (CAD). A decreased endogenous fibrinolytic system and prothrombotic factors are supposed to influence coronary thrombosis. It was our aim to investigate the predictive value of tissue plasminogen activator (t-PA) antigen, von Willebrand Factor, Lipoprotein (a) and anti-cardiolipin antibodies for major adverse coronary events in patients with stable CAD in a prospective cohort study of more than 10 years. We observed 141 patients with angiographically proven CAD for a median follow-up period of 13 years. t-PA antigen was the only marker predicting coronary events (logistic regression, p = 0.044) with a poor prognosis for patients in the 5th quintile with an odds ratio of 7.3 (compared to the 1st quintile). The odds ratio even increased to 10.0 for coronary events associated with the "natural course" of CAD excluding events due to restenosis. t-PA antigen had a slightly higher prognostic power (ROC curve; AUC = 0.69) than fasting glucose (AUC = 0.68) and cholesterol (AUC = 0.67). Triglycerides influenced plasma levels of t-PA antigen (regression, p < 0.001). The predictive value of t-PA antigen remained significant after adjustment for inflammation (logistic regression, p = 0.013) and extent of CAD (p = 0.045) but disappeared adjusting for insulin resistance (p = 0.12). In conclusion t-PA antigen predicted coronary events during a very long-term follow-up with a comparable prognostic power to established cardiovascular risk factors. Markers of insulin resistance influenced t-PA antigen and its predictive value.
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PMID:Circulating t-PA antigen predicts major adverse coronary events in patients with stable coronary artery disease--a 13-year follow-up. 1288 83

Some studies have suggested that thrombotic and fibrinolytic disorders may be etiologic causes of osteonecrosis of the femoral head. A case-control study was done to determine whether these disorders are associated with osteonecrosis of the femoral head in East Asian patients with nontraumatic osteonecrosis of the femoral head. Twenty-four consecutive patients who had been diagnosed as having nontraumatic osteonecrosis of the femoral head were matched with 24 control subjects for gender, age (1-year range), and the time of presentation (1-year range). Thrombotic factors including protein C activity, protein S activity, antithrombin III, anticardiolipin antibody immunoglobulins G and M, and lupus antibody were investigated. Fibrinolytic factors including tissue-plasminogen activator, plasminogen activator inhibitor-1, tissue-plasminogen activator and plasminogen activator inhibitor-1 ratio, lipoprotein (a), and plasminogen also were investigated. There were no significant differences in the levels of thrombotic and fibrinolytic factors. In eight patients with idiopathic osteonecrosis, anticardiolipin antibody immunoglobulin G, an antiphospholipid antibody which is associated with thrombotic phenomena, was lower than that in respective control subjects. These data do not confirm an etiologic role for thrombotic and fibrinolytic disorders in East Asian patients with nontraumatic osteonecrosis of the femoral head.
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PMID:Role of thrombotic and fibrinolytic disorders in osteonecrosis of the femoral head. 1464 26

Thrombus formation within hemodialysis catheters contributes to inadequate dialysis and adverse patient outcomes. A thrombolytic agent may be required to restore patency and improve blood flow. This study evaluates the efficacy of instilling low dose (1 mg/ml) t-PA in catheter lumens to restore patency in malfunctioning catheters. t-PA was utilized to treat suspected catheter thrombus over a four-month period. Seventeen patients with 21 catheters (12 temporary, 9 permanent) received 40 doses of t-PA. Catheter function was restored in 39 of 40 cases (97.5%). Significant improvement in blood flow was confirmed by paired t-test (p < 0.001). Sustained improvement in blood flow was confirmed by ANOVA (p < 0.001). The mean primary patency of all catheters was 29.7 days (SD = 27.0 days). No adverse patient effects were noted. These results demonstrate that t-PA can safely and effectively restore blood flow and extend patency in hemodialysis catheters.
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PMID:Tissue plasminogen activator (t-PA) efficacy in the restoration of hemodialysis catheter function. 1571 85


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