Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.68 (tissue plasminogen activator)
 11,311 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Alteplase is the product of recombinant DNA technology and is chemically identical to endogenous tissue-type plasminogen activator: Plasminogen is converted to plasmin by alteplase, and fibrinolysis of blood thrombi is subsequently stimulated. Alteplase is now firmly established as a treatment of choice in the management of acute myocardial infarction. The efficacy of intravenous alteplase in the treatment of pulmonary thromboembolism has also been established and appears to be similar to that of streptokinase and urokinase in this indication and in arterial thrombotic occlusion. However, its use in this latter indication and in other vascular disorders has not been as extensively documented. Although trials demonstrating the efficacy of intravenous alteplase in patients with deep vein thrombosis and intra-arterial alteplase in patients with arterial thrombotic occlusion exist, reliable data on the efficacy of the fibrinolytic in ischaemic stroke and intracranial haemorrhage are scarce. Little clinical benefit is apparent in patients with unstable angina, although careful use may be warranted in those with definite pretreatment coronary thrombi. Of concern, there is a suggestion that general use of alteplase in patients with unstable angina may be associated with increased incidence of myocardial infarction. The incidence of major haemorrhage associated with alteplase therapy increases with increasing dose and appears to be similar to that seen with other fibrinolytic agents. Thus, further well-designed studies of the use of alteplase in ischaemic stroke and cerebral haemorrhage are required. However, a small subset of patients with unstable angina and definite pretreatment coronary thrombi may benefit from alteplase therapy. Further, preliminary data suggest efficacy in the therapy of deep vein thrombosis and arterial thrombotic occlusion, and alteplase has a proven place in the fibrinolytic treatment of pulmonary thromboembolism.
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PMID:Alteplase. A reappraisal of its pharmacology and therapeutic use in vascular disorders other than acute myocardial infarction. 852 60

Deep vein thrombosis may begin during surgery with the tourniquet inflated. Arterial levels of fibrinopeptide A, thrombin-antithrombin complexes, D-dimer, tissue plasminogen activator (t-PA) activity, and t-PA antigen were measured before surgery, during surgery with the tourniquet inflated, and following deflation of the tourniquet in 12 patients undergoing total knee arthroplasty. Minimal increases in fibrinopeptide A, thrombin-antithrombin complexes, and D-dimer were noted during surgery with the tourniquet inflated, but significant increases occurred immediately following deflation of the tourniquet. In 10 patients, intravenous heparin administration significantly suppressed the rise in fibrinopeptide A, but did not significantly alter the increases in either thrombin-antithrombin complexes, D-dimer, t-PA antigen, or t-PA activity. This study provides further evidence that deep vein thrombosis begins during surgery.
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PMID:Changes in circulatory indices of thrombosis and fibrinolysis during total knee arthroplasty performed under tourniquet. 852 13

Impaired fibrinolytic function, mainly due to an elevation of the plasma PAI-1 concentration, is a common finding in patients with thrombotic disease. Unfortunately, regarding patients with idiopathic deep vein thrombosis (DVT), no reliable prospective or genetic studies have been published. Concerning postoperative DVT, preoperatively increased PAI-1 level seems to predict a postoperative DVT in patients subjected to hip surgery. Several longitudinal cohort studies of patients with manifest coronary heart disease (CHD) have linked elevated plasma PAI-1 or tPA antigen concentrations to future cardiovascular events, particularly myocardial infarction. Before PAI-1 can be regarded as a risk factor in the conventional epidemiological sense, its relationship to myocardial infarction must be demonstrated in prospective studies of healthy populations. Regulation of the plasma concentration of PAI-1 is complex and at present not well understood. Multiple interactions with disturbances of both carbohydrate and lipoprotein metabolism are evident. Many studies have been carried out in cultured cells, but data can hardly be transformed into human pathophysiology. It seems that both environmental and genetic factors are of importance for the plasma PAI-1 concentration. Recently, knowledge of the importance of genetic factors involved in the regulation of plasma PAI-1 concentration has become available. Interestingly, preliminary data suggest that the 4G/5G polymorphism located within the PAI-1 promoter is connected to CHD. More data on larger patient groups are needed and will certainly shed new light on the importance of impaired fibrinolytic function in the etiology of CHD in the near future.
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PMID:Plasminogen activator inhibitor 1 (PAI-1) in plasma: its role in thrombotic disease. 857 29

Many reports have demonstrated an abnormal fibrinolysis in a subset of patients with deep vein thrombosis. We have studied systemic global fibrinolytic activity and protein concentrations of tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor type 1 (PAI-1) in plasma of 25 young patients with a previous instance of spontaneous deep vein thrombosis documented by phlebography and in 50 healthy controls. The two populations were comparable with respect to a number of base-line variables (age, height, weight, etc.), while the patients had significantly lower fibrinolytic activity (p < 0.02), and significantly higher protein concentrations of t-PA (p < 0.0001) and PAI-1 (p < 0.0006). We used probit scale plots to identify the consequence of different cut-off points to separate patients from controls. Reasonable separation could be obtained for t-PA with a cut-off point of 5.2 ng/ml and for PAI-1 18 ng/ml. The sensitivity and specificity for these cut-off points were for t-PA 73% (95% confidence interval 63%-84%) and for PAI-1 67% (confidence interval 55%-77%). The negative predictive value with a cut-off point t-PA concentration of 5.2 ng/ml was 85% (95% confidence interval 70%-94%). We observed a significantly negative association between concentration of t-PA and fibrinolytic activity (rs = -0.47; p < 0.005) and also between PAI-1 and fibrinolytic activity (rs = -0.78; p < 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Does low protein concentration of tissue-type plasminogen activator predict a low risk of spontaneous deep vein thrombosis? 858 12

The main complication of totally implantable venous access devices is deep venous thrombosis on catheter. It may dramatically reduce the already limited venous capacity of patients undergoing chemotherapy and obturate catheters, causing pulmonary embolism or functional disorders. These thromboses usually involve veins of the superior vena cava system where the catheters are implanted. Generally, they occur early, are extensive and often asymptomatic. Doppler ultrasonography is the diagnostic investigation of choice, phlebography being reserved for particular cases or to specify the limits of the thrombus. In a series of 412 vein access devices implanted and systematically monitored by Doppler ultrasonography, we found 57 thromboses (13.8%), 15 partial and 42 complete. The lowest thrombosis rate was observed in the right internal jugular vein (10% vs 20 to 23%, p = 0.006). Thirty-two patients received a systemic fibrinolytic treatment, 16 with streptokinase (SK), five with urokinase (UK), four with tissue plasminogen activator (rt-PA) and seven with SK/UK association. No serious side effects were observed. Sixteen repermeabilizations (50% of fibrinolysis) were obtained. There were no significant differences with respect to the fibrinolytic, the initial characteristics of thrombosis or the patients. Patients without fibrinolysis received 3 weeks of low molecular weight heparin (curative doses) then warfarin. Only one patient was repermeabilized with this treatment (significative difference with fibrinolysis: p = 0.009). Fibrinolysis is indicated in symptomatic thrombosis and/or in cases of extension to the innominate vein or the superior vena cava. Systematic monitoring by Doppler ultrasonography and prophylactic anti-thrombotic treatment are recommended in patients with implantable venous access devices in order to decrease the occurrence of thromboses, to detect asymptomatic patients at an early stage and to increase the effectiveness of fibrinolysis.
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PMID:[Fibrinolysis of deep venous thrombosis on implantable perfusion devices. Apropos of a consecutive series of 57 cases of thrombosis and 32 cases of fibrinolysis]. 868 80

In our experience, severe pulmonary tuberculosis (PTB) is often complicated by deep venous thrombosis (DVT). Because of the association between inflammation and haemostatic changes that can result in a hypercoagulable state, we have prospectively examined such predisposing factors in representative patients. Sequential analyses in a control group with active PTB showed anaemia, thrombocytosis, elevations in plasma fibrinogen, fibrin(ogen) degradation products (FDP), tissue plasminogen activator (t-PA) and inhibitor (PAI-1) with depressed antithrombin III levels. Age, sex and disease matched individuals with venographically proven DVT had higher FDP (15.8 +/- 14.3 v 3.2 +/- 1.7 micrograms/ml:P < 0.01), t-PA (19.4 +/- 14.9 v 11.3 +/- 0.8 ng/ml:P < 0.01), and functional PAI-1 activity (11.6 +/- 6.3 v 4.2 +/- 4.1:P < 0.01) with lower platelet counts (347 +/- 110 v 563 +/- 230 x 10(9)/1:P < 0.01). Fibrinogen levels in all patients rose during the first 2 weeks of therapy and, together with related disturbances, corrected within 12 weeks. In conclusion, elevated plasma fibrinogen with impaired fibrinolysis coupled with a decrease in antithrombin III and reactive thrombocytosis would appear to favour the development of DVT in PTB.
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PMID:Acute-phase response and the hypercoagulable state in pulmonary tuberculosis. 870 31

Hip arthroplasty is associated with a high frequency of postoperative solitary proximal deep vein thrombosis which seems most frequently observed when bone cement is used for prosthesis fixation. Eighteen pigs underwent hemiarthroplasty, eight with cement-fixed prostheses and eight with non-cement prosthesis installation. Levels of thrombin-antithrombin (TAT) complexes, tissue plasminogen activator (t-PA) activity and plasminogen activator inhibitor 1 (PAI-1) activity were determined in femoral vein blood from both limbs during and after surgery. On the operated side, TAT increased during bone traumatization followed by a substantial rise in t-PA activity and a gradual decline in PAI-1 activity. This indicates a local per- and post-operative sequential activation of coagulation and fibrinolysis followed by a fibrinolytic shutdown, all reflected in femoral vein blood on the operated side. In the animals receiving noncemented hip prostheses, the same pattern of activation of coagulation and fibrinolysis occurred on the operated side. This was, however, less marked than with the cement-fixed prostheses. Postoperative scanning electron microscopic (SEM) examination of the femoral veins showed thrombi on the operated side in 62% of the animals in the cement group and 25% in the non-cement group. In an additional study with eight animals undergoing cement-anchored hip prosthesis operations the levels of TAT, t-PA and PAI-I were analysed in femoral vein blood, mixed venous blood and arterial blood. Significantly higher levels were found in femoral vein blood compared with mixed venous blood while no significant change was found in arterial blood compared with mixed venous blood. The hyperthermia induced by curing bone cement was effectively conducted by the implanted prosthesis and did not seem to exert major influence on the activation of coagulation. Extreme rotation of the limbs during surgery did not in itself induce visible vein wall damage as judged by SEM. These studies indicate that traumatization of bone marrow during hip surgery induce a marked local activation of coagulation and a high incidence of deep vein thrombosis in proximal veins, in particular if bone cement is used for prosthesis fixation.
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PMID:The role of bone traumatization in the initiation of proximal deep vein thrombosis during cemented hip replacement surgery in pigs. 882 20

Thrombolysis today has become a routine option not only in the treatment of acute myocardial infarction but also in many other manifestations of thromboembolic disease. Until one decade ago, only two plasminogen activators, streptokinase and urokinase, were available for clinical use. They were characterized by limited thrombolytic potencies and major side effects including systemic fibrinogen breakdown, bleeds and stroke. This has prompted the search for new plasminogen activators with better pharmacological and clinical profiles. The first such new plasminogen activators were Anistreplase, a chemically modified version of the streptokinase-plasminogen-activator-complex and tissue-type plasminogen-activator produced by recombinant technology. Both new substances have fueled the development in modern thrombolytic treatment. While the clinical progress with t-PA was confirmed in large, double-blind, randomized, multicenter trials, no real superiority of anistreplase over the traditional plasminogen activators urokinase and streptokinase has been substantiated. While the clinical use of t-PA today has been established for acute myocardial infarction, pulmonary embolism and deep vein thrombosis, current research is focused on further plasminogen activators with further improved thrombolytic properties. This review summarizes the current knowledge on the biochemical and pharmacological properties of the first, second and future generation of plasminogen activators.
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PMID:Thrombolytic agents--an overview. 885 12

A 27-year-old woman, after 31 weeks of amenorrhoea during her second pregnancy, developed a left external iliac and femoral deep vein thrombosis, confirmed by venous ultrasonography and magnetic resonance imaging. The infusion of tissue plasminogen activator (rt-PA: 1.2 mg/kg, i.e. 80 mg over 3 hours), on the 2nd day, allowed revascularization of the femoral junction, while the external iliac vein remained occluded. The patient did not develop pulmonary embolism or haemorrhage, particularly obstetric haemorrhage. The subsequent pregnancy was uneventful until delivery, six weeks later, of a normal child. Three years later, the patient has no sequelae of her deep vein thrombosis. When required by the patient's condition, it seems that rt-PA can be used to treat severe deep vein thrombosis during pregnancy, either isolated or complicated by pulmonary embolism. Very rigorous cardiological, obstetric and laboratory surveillance is essential. A sufficient dosage, identical to that used in clinical settings other than pregnancy and a brief treatment duration (2 to 3 hours) are probably more effective and more reliable than lower doses continued for several days. However, the risk of haemorrhage remains difficult to predict and its prognosis, especially foetal, is often very poor. A larger series of cases is therefore necessary before this drug can unreservedly recommended in pregnant women.
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PMID:[Ilio-femoral vein thrombosis treated with tissue plasminogen activator in a pregnant woman]. 903 5

The authors report a study on the hemostatic status of a group of patients with deep venous thrombosis in order to highlight the possible pathogenetic responsibility of blood coagulative disorders in the genesis of thrombosis. The group consisted of 27 patients (14 males, 13 females, mean age 48 +/- 4 years) with deep venous thrombosis of the lower limbs (clinical symptoms were primary in 21 cases, secondary in 6 cases) diagnosed on the basis of clinical data and ultrasonographic instrumental findings. Fourteen normal subjects were also examined as a control group (12 males, 2 females, mean age 28 +/- 5 years). Venous blood was collected on fasting from patients and controls to examine the following parameters: fibrinogen (F), factor VII (F VII), antithrombin III (AT III), protein C (PC), protein S (PS) using coagulometric methods (IL), and tissue plasminogen activator (tPA), plasminogen activator inhibitor (PAI-1), fibrinopeptide A (FPA), betathromboglobulin (BTG) and dimer-D (D-D) using ELISA methods (Boehringer). Patients with deep venous thrombosis showed a significant increase in F, FVII, tPA and D-D levels compared to controls, whereas a significant reduction was observed in PAI-1. Nonsignificant variations were found for AT III, PC, PS and BTG. In the light of these results the authors affirm that: high fibrinogen and factor VII levels are highly prognostic for thrombosis in patients with deep venous thrombosis; the importance of the lack of inhibitory factors (AT III, PC, PS) is confined to individual genetically predisposed cases; there is an efficacious hyperfibrinolytic reactive response to the presence of thrombus (increase in tPA and D-D, reduction of PAI-1).
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PMID:[Hemostatic status in subjects with deep venous thrombosis]. 905 19


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