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 defibrinating agent ancrod has had limited clinical trial, but appears to give no advantages over heparin. Intravenous infusion of dextran, a glucose polymer, has been shown to have an antithrombotic effect in many experimental models of thrombosis. However, the evidence that dextran is a clinically valuable antithrombotic drug is conflicting. A number of controlled randomized studies have shown that dextran can prevent postoperative venous thromboembolism when a large volume of dextran 40 or 70 was infused rapidly during and after surgery. However, blood volume expansion during dextran treatment prohibits its use in patients with reduced cardiac reserve, and infrequent though sometimes severe, allergic reactions have been reported. Evidence that dextran is of value for the treatment of venous or arterial thromboembolism comes from uncontrolled studies and is not convincing. Many compounds have been shown to inhibit platelet function in vitro but only five of these drugs have been extensively evaluated as prophylactic or therapeutic antithrombotic agents in man. These are aspirin, sulphinpyrazone, dipyridamole, hydroxychloroquine and clofibrate. They have been evaluated mainly in patients with cerebral vascular disorders, coronary artery disease, peripheral artery ischaemia, venous thromboembolism, prosthetic heart valves, and in patients with arteriovenous shunts. The evaluation of the clinical effect of the platelet function suppressing drugs is in its early stages, but they appear to differ from each other in the spectrum of their clinical effectiveness, and they may be more effective in arterial than in venous thromboembolic disorders. Their role in the management of cerebral vascular disease and coronary artery disease is still uncertain, and should be clarified by the results of a number of multi-centre, prospective, randomized studies which are currently in progress. Three types of thrombolytic drugs have been evaluated clinically; the plasminogen activators streptokinase and urokinase, proteolytic enzymes such as plasmin, and agents which increase the level of endogenous plasminogen activator (e.g. anabolic steroids). Of these, the plasminogen activators now have a definite place in clinical practice. The plasminogen activators accelerate the lysis of recent venous thrombi and pulmonary emboli, and of arterial thrombi or emboli. Thrombolytic therapy with these agents should be considered particularly in patients with recent major pulmonary embolism, as lysis of recent emboli is rapid and substantial. It should also be considered in patients with recent extensive venous thrombosis, because total lysis of venous thrombi has been reported to result in long-term preservation of valve function, and is likely to prevent postphlebitic syndrome, though this has not been proven. However, plasminogen activator therapy carries a higher risk of bleeding than heparin treatment...
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PMID:Antithrombotic drugs: part II. 78 6

Atherosclerosis is probably caused by multiple interacting factors such as disturbed lipid metabolism; endothelial cell damage, leading to platelet aggregation and monocyte invasion with the release of mitogenic factors; and disorders of fibrin balance, leading to persisting fibrin deposits. Deficient fibrinolysis may (1) predispose to fibrin deposition and contribute to the pathogenesis of atherosclerosis and (2) contribute to occlusive thrombus formation on fissured plaque, provoking atherothrombosis. Prospective epidemiologic studies have so far not provided definitive evidence that deficient fibrinolysis constitutes a significant risk factor for the development of atherosclerosis. Two recent findings, however, strongly suggest a contribution: (1) Increased lipoprotein(a) levels that reduce tissue-type plasminogen activator (t-PA)-mediated clot lysis are a clear risk factor for atherosclerosis; and (2) increased plasminogen activator inhibitor-1 (PAI-1) levels in patients with disturbed glucose tolerance predispose to an accelerated development of atherosclerotic disease. However, deficient fibrinolysis constitutes a risk factor for the development of thrombotic complications (acute myocardial infarction) in patients with coronary artery disease. The potential role of deficient fibrinolysis in the pathogenesis of atherosclerosis and of atherothrombosis suggests that drugs normalizing deficient endogenous fibrinolysis by either reducing PAI-1 synthesis or by stimulating endogenous t-PA synthesis may be of clinical value. Although regulation of the gene expression of PAI-1 and t-PA is presently under active investigation, no potent specific and safe agents to downregulate PAI-1 or to upregulate t-PA have as yet been identified. Retinoic acid appears to be a specific inducer of t-PA synthesis in human endothelial cells in culture and may constitute a model for the development of drugs that stimulate endogenous t-PA synthesis.
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PMID:On the role of coagulation and fibrinolysis in atherosclerosis. 134 93

Two hundred five men, 40 to 70 years of age, admitted to the coronary care unit with unstable coronary artery disease (unstable angina or non-Q wave myocardial infarction), were randomized to double-blind placebo-controlled treatment with an intravenous infusion of recombinant tissue-type plasminogen activator (rTPA), 1 mg/kg body weight (maximum 100 mg) during 4 hours, in addition to aspirin, heparin, and beta-blockade. No severe complications occurred. Myocardial ischemia, defined as myocardial infarction, incapacitating angina despite medication, or signs of ischemia at the exercise test, was reduced by treatment with rTPA compared with placebo both at discharge, 53% compared with 70% (p = 0.02), and at 1 month, 61% compared with 80% (p = 0.005). Signs of myocardial ischemia during the exercise test were reduced at discharge 51.0% compared with 68% (p = 0.03) and at 1 month 48% compared with 62% (p = 0.09). Coronary angiography after 1 month showed no difference in major coronary lesions between the groups, nor was there any reduction in the number of performed coronary revascularization procedures. In conclusion, treatment with rTPA in unstable coronary artery disease in men reduced myocardial ischemia but did not significantly reduce the need for revascularization in long-term follow-up.
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PMID:Thrombolysis with recombinant human tissue-type plasminogen activator during instability in coronary artery disease: effect on myocardial ischemia and need for coronary revascularization. TRIC Study Group. 146 94

The t-PA/PAI-1 complex is a good indicator of the release of fibrinolysis activators and inhibitors from the vascular wall, but its clinical significance in chronic ischemic heart disease is unclear. The plasma levels of tissue-type plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1), and the t-PA/PAI-1 complex (including various coagulation factors) were assayed in 72 patients with coronary artery disease (CAD) and 29 control (C) subjects. The CAD patients were subdivided into 3 groups: single-vessel disease (G1, n = 30), double-vessel disease (G2, n = 20), and triple-vessel disease (G3, n = 22). The patients with triple-vessel disease had higher fibrinogen values (G3: 318 +/- 75 mg/dl, C: 263 +/- 56), factor VII activity (G3: 143 +/- 36%, C: 123 +/- 14), and t-PA antigen levels (G3: 4.7 +/- 0.8 ng/ml, C: 3.3 +/- 0.7) than controls. Patients with double- and triple-vessel disease also showed higher levels of factor VIII, vWF antigen, thrombin-antithrombin III complex (G1: 2.3 +/- 0.6 ng/ml, G2: 2.7 +/- 0.5, G3: 3.1 +/- 0.5, C: 2.0 +/- 0.5), and t-PA/PAI-1 complex (G1: 13.9 +/- 6.1 ng/ml, G2: 16.4 +/- 4.6, G3: 18.2 +/- 5.9, C: 10.7 +/- 4.9) than control subjects. The t-PA/PAI-1 complex levels were correlated significantly with the activities of factors VII and VIII and the thrombin-antithrombin III complex. These findings suggest that patients with CAD have greater blood coagulability than controls, and that this difference is related to the severity of the disease.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Plasma t-PA/PAI-1 complex and blood coagulability in patients with coronary artery disease. 152 91

Fibrinolytic therapy is a major advance in the treatment of coronary artery disease. A marked elevation in plasma and urinary metabolites of thromboxane A2 (TXA2) after administration of thrombolytic therapy has been observed and has been related to a direct effect of thrombolytic drugs on platelets. To test this hypothesis we evaluated the 11-dehydro-thromboxane B2 (11-d-TXB2) level, as an index of platelet activation, in 20 healthy subjects and in 30 patients with acute myocardial infarction (AMI). Patients with infarction received streptokinase (n = 8), recombinant tissue-type plasminogen activator (rt-PA) (n = 8), or thrombolytic therapy preceded by acetylsalicylic acid (n = 7) or were treated without thrombolytic therapy (n = 7). The urinary 11-d-TXB2 level in healthy control subjects was 327 +/- 126 pg/mg creatinine. A significant increase was observed in patients with AMI with no difference between those who received no thrombolytic therapy (673 +/- 283 pg/mg creatinine in the first 12 hours) and those who received streptokinase (833 +/- 613 pg/mg creatinine) or rt-PA (836 +/- 653 pg/mg creatinine). Patients pretreated with acetylsalicylic acid had urinary 11-d-TXB2 values ranging between 361 and 155 pg/mg creatinine. A significant difference in 11-d-TXB2 values was observed only when patients who were reperfused were separated from those who remained occluded according to angiographic criteria (1085 +/- 498 vs 391 +/- 227 pg/mg creatinine in the first 12 hours, p less than 0.001). We conclude that reperfusion and not thrombolytic agents per se appears to be the factor that induces platelet activation and consequently facilitates reocclusion.
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PMID:Importance of reperfusion on thromboxane A2 metabolite excretion after thrombolysis. 153 6

The fibrinolytic capacity of the blood mainly depends on the amount of tissue-plasminogen activator (t-PA) antigen and plasminogen activator inhibitor (PAI). In this study the fibrinolytic response to a venous occlusion test (VOT) was measured in 109 patients with angiographically documented coronary artery disease (CAD) and in 20 healthy volunteers at comparable age (controls). CAD-patients had higher plasma plasminogen activator inhibitor capacity before (24.4 +/- 11.0 vs. 15.4 +/- 5.2 arbitrary units [AU/ml]; p less than 0.0002) and after VOT (19.6 +/- 13.2 vs. 10.9 +/- 5.3 AU/ml; p less than 0.0001) compared with controls. Furthermore they showed significant lower plasma t-PA activity after VOT (3.0 +/- 6.8 vs. 6.6 +/- 10.6 AU/ml; p less than 0.0001). However there were no difference between both groups in plasma t-PA antigen levels after VOT (17.3 +/- 12.1 vs. 18.7 +/- 14.4 ng/ml). In 10% of patients the decrease in fibrinolytic activity resulted from a lower t-PA release ("lower" was defined as mean minus one standard deviation of the control group). 40% showed elevated plasma PAI capacity before VOT ("elevated" was defined as mean plus two standard deviations of the control group). Both caused significantly reduced post occlusion plasma t-PA activity and prolonged Euglobulin clot lysis time (p less than 0.003). A positive correlation was found between PAI capacity and serum triglyceride levels. Reduced fibrinolytic activity in 109 patients with coronary heart disease based either on a decrease in t-PA antigen release or a increased in PAI capacity in comparison with healthy controls. The mechanism of these findings is not yet well-known.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Decreased fibrinolytic capacity in coronary patients by increased plasminogen activator inhibitor activity]. 158 60

Fibrinolysis and lipid disturbances have been considered as independent risk factors for coronary artery disease. Besides this, lipoprotein(a), which is characterized by its homology with plasminogen may interfere with the fibrinolytic function. To evaluate the eventual correlation between fibrinolytic parameters, lipoprotein (a) and other risk factors, 46 patients with coronary artery disease (34 with chronic angina pectoris and 12 with myocardial infarction) were studied. Increased basal values of t-PA antigen (8.2 and 6.6 vs. 4.2 ng/ml) but decreased response after stimulus (2.2 and 1.8 vs. 3.8 ng/ml) and increased levels of lipoprotein(a) (24.7 and 35.9 vs. 10.5 mg/dl) were the most relevant differences between coronary artery disease patients and controls. No correlation between lipoprotein(a) and fibrinolytic parameters was found. Therefore plasma concentration of the main plasma fibrinolytic parameters and lipoprotein(a) seem to be unrelated though the relevance of this interaction at a local level needs to be studied.
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PMID:Fibrinolytic parameters and lipoprotein (a) levels in plasma of patients with coronary artery disease. 183 82

To determine whether there are differences in responses to thrombolytic therapy in certain populations, the data for the Thrombolysis and Angioplasty in Myocardial Infarction (phase 1) study were analyzed for black and white patients. Baseline variables including risk factors and extent of coronary artery disease were similar in the 352 white and 24 black patients. The time from onset of chest pain to recombinant tissue-type plasminogen activator (rt-PA) therapy and rt-PA dosing regimens were the same in the two groups. The patency rate of the infarct-related artery at 90 minutes was 91% for blacks and was 72% for whites (p = 0.051). Blacks displayed significantly lower nadir fibrinogen levels (0.57 +/- 0.62 versus 1.3 +/- 0.76 g/l, p less than 0.0001), greater delta fibrinogen (baseline-nadir) (2.7 +/- 1.1 versus 1.7 +/- 1.1 g/l, p less than 0.0001), and increased peak levels of fibrin(ogen) degradation products (837 +/- 865 versus 245 +/- 475 micrograms/ml, p less than 0.0001). rt-PA antigen levels tended to be higher in blacks than in whites (2.8 +/- 2.2 versus 2.2 +/- 3.2 micrograms/ml [p = 0.10] at the peak and 1.6 +/- 1.3 versus 0.99 +/- 1.4 micrograms/ml [p = 0.06] at the end of the maintenance infusion). Major clinical outcomes including survival until time of hospital discharge (92% black versus 93% white, p = 0.68) were not significantly different. However, despite undergoing fewer angioplasty procedures (25% versus 46.3%, p = 0.047), blacks received more transfusions (58.8% versus 19.5% were administered greater than or equal to 2 units packed erythrocytes, p = 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Racial differences in responses to thrombolytic therapy with recombinant tissue-type plasminogen activator. Increased fibrin(ogen)olysis in blacks. The Thrombolysis and Angioplasty in Myocardial Infarction Study Group. 193 93

A 20-min venous occlusion and a desmopressin acetate (DDAVP, 0.4 microgram.Kg-1, 15 min) infusion test have been compared to evaluate fibrinolytic capacity in proven coronary artery disease. Basal values of plasma tissue plasminogen activator (t-PA) activity and antigen and of t-PA inhibitor (PAI) were normally distributed in this patient group. However, after both stimuli, highly significant (P less than 0.005) increases of t-PA antigen and activity have been observed. Renormalization of t-PA levels after DDAVP infusion occurred more rapidly for antigen (120 min) than for activity concentrations (greater than 240 min). A DDAVP infusion test seems more appropriate for evaluation of the fibrinolytic capacity as the induced decrease in PAI level was significant (P less than 0.005) and lasted for at least 240 min, while it was not significant for the venous occlusion test.
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PMID:Comparison of the fibrinolytic response to desmopressin acetate (DDAVP) infusion versus venous occlusion in patients with coronary artery disease. 190 28

The increase in Lp(a) is strongly correlated with premature coronary artery disease. The Apo(a) has striking homology to plasminogen. It was found in an in vitro purified system that Lp(a) competes with both plasminogen and tissue-type plasminogen activator (tPA) for fibrin binding sites, thus resulting in a decrease in fibrin-dependent plasminogen activation. In this study, plasma fibrinolysis was studied in a young patient who had a consistently high level of Lp(a) (198 mg/dl) and had suffered from cerebral thrombophlebitis 12 months previously. The patient had normal levels of plasma plasminogen and fibrinogen. The euglobulin lysis time before and after venous occlusion was not prolonged, and after the addition of tPA to the patient's plasma or whole blood, the clot lysis time was normal. The same result was obtained when the patient's plasma was depleted of Lp(a) before clotting. When the patient's plasma serpins were inhibited, plasminogen activation by tPA in the presence of several fibrin concentrations was normal, suggesting that the formation of the ternary complex tPA - plasminogen - fibrin was not inhibited by the presence of high levels of Lp(a). It is concluded that a consistently high level of Lp(a) in this patient did not inhibit tPA-dependent fibrinolysis, and the thrombotic episode was not therefore related to deficient thrombolysis.
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PMID:Absence of inhibition by lipoprotein (a) inhibition of tPA induced thrombolysis in a patient's plasma milieu. 196 96


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