Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.6 (thromboplastin)
13,278 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two hundred and four consecutive patients with venographically confirmed deep vein thrombosis (DVT) were randomised either to a low molecular weight heparin, Fragmin, administered subcutaneously (s.c.) once daily as a fixed dose of 200 IU anti-factor Xa/kg or to continuous intravenous infusion of unfractionated heparin (UFH). The UFH dose was adjusted to maintain the activated partial thromboplastin time between 1.5 and 3.0 times the upper limit of the reference value at each centre. Fragmin or UFH was given for a minimum of 5 days until anticoagulation with warfarin, given from day 1, was established (i.e. an Internation Normalised Ratio, of 2.0-3.0). A second venogram was obtained after Fragmin or UFH treatment. There were no significant differences in the change in mean Marder score before and after treatment between the two treatment groups, irrespective of thrombus localisation. No major bleeding events, symptomatic pulmonary embolism, symptomatic thrombosis progression or death occurred during hospitalisation. Eight documented venous thromboembolic events occurred before the follow-up visit 6 months after randomisation: 5 in patients treated with Fragmin and 3 in those treated with UFH. Six of these events occurred after cessation of warfarin treatment. In conclusion Fragmin given s.c. once daily in a fixed dose adjusted for body weight, is no less effective or safe than a continuous infusion of UFH in the initial treatment of acute DVT.
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PMID:Comparison of once-daily subcutaneous Fragmin with continuous intravenous unfractionated heparin in the treatment of deep vein thrombosis. 783 49

Treatment monitoring based on a laboratory parameter increases the efficacy and safety of standard heparin therapy, but it is not known if this also applies to low-molecular-weight heparin (LMWH) therapy of acute deep vein thrombosis (DVT). In a prospective randomized trial involving 122 consecutive patients, group A (58 patients) received a weight adjusted dose of Fragmin (100 IU/kg) subcutaneously twice a day throughout the treatment period (10 days +/- 1), while in group B (64 patients) the dosage was based on the results of an anti factor Xa (anti Xa) amidolytic assay to obtain a target concentration from 0.5 to 1 IU/ml. AntiXa and antithrombin activities were also measured retrospectively on frozen plasma from all patients. The two regimens were comparable in terms of hemorrhagic complications (4 in group A and 3 in group B). Bilateral ascending phlebography was performed before inclusion and at the end of LMWH treatment. Treatment efficacy, based on Marder's score, did not differ between the two groups (p = 0.3). Dosage adjustment to between 0.5 to 1 IU anti-Xa/ml does not therefore appear to improve the efficacy or safety of LMWH treatment. However, correlations between the change in Marder's score and both anti-Xa (p < 0.001) and antithrombin activity (p < 0.001) were observed, suggesting a relationship between the degree of FXa or thrombin inhibition and antithrombotic activity.
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PMID:Adjusted versus fixed doses of the low-molecular-weight heparin fragmin in the treatment of deep vein thrombosis. Fragmin-Study Group. 797 34

A review based on 17 randomised studies on low molecular weight heparin (LMWH) versus unfractionated heparin (UFH) in the treatment of objectively verified deep venous thrombosis (DVT) is presented. Long-term treatment with LMWH was compared with long-term UFH in two studies and with warfarin in one study. In the rest of the studies LMWH and UFH were used during initiation of oral anticoagulant therapy, and these studies were included in a meta-analysis. The relative risk of progression of DVT during LMWH treatment compared with UFH was 0.63 (95% confidence interval: 0.39-1.00) and the relative risk of major bleeding was 0.41 (95% confidence interval: 0.24-0.70). There was no significant difference in the reduction of Marder score during treatment (LMWH 5.0 versus UFH 3.8) or in the frequency of new symptomatic, scintigraphically or angiographically verified pulmonary embolism (LMWH 0.6% versus UFH 1.1%). The frequency of complications seemed independent of whether LMWH was administered once or twice daily. Monitoring of LMWH treatment is not considered necessary but determination of anti-factor Xa in plasma is recommended if bleeding occurs during treatment with LMWH.
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PMID:[Low molecular weight heparin versus unfractionated heparin in the treatment of deep venous thrombosis--a meta-analysis]. 798 76

A quantitative and non-occlusive deep vein thrombosis model was developed in rabbits. We used this model to test the antithrombotic activity of the prothrombinase complex inhibitors factor rXai and its chemical analog glutamyl-glycyl-arginyl chloromethyl ketone inactivated human factor Xa (EGR-Xai), along with the thrombin inhibitors D-phenylalanyl-prolyl-arginyl chloromethyl ketone (PPACK) and heparin. Dose dependent effects of the inhibitors during constant infusion were monitored. Measurements included thrombus weights, hemostatic parameters and both cuticle and ear bleeding times. In this model, factor rXai and EGR-Xai had comparable in-vivo efficacy, and showed 80%-93% inhibition at plasma levels of 6.5 nM (rXai) and 8 nM (EGR-Xai). Effects on ex-vivo clotting times varied among the inhibitors. At 80-100% thrombus inhibition, factor rXai and EGR-Xai had no statistically significant effect, while PPACK extended thrombin clotting time (TCT) times 2.3-fold, and heparin prolonged both activated partial thromboplastin time (APTT), prothrombin time (PT) and TCT ex-vivo clotting times 6.9-, 1.2-, and 7-fold respectively. At these dosages, cuticle and ear bleeding times were prolonged for all inhibitors and showed increases of 177%-389% (cuticle) and 45%-129% (ear). Our results demonstrate that direct inhibition of prothrombinase complex assembly is effective in arresting venous thrombosis.
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PMID:A comparative study of prothrombinase and thrombin inhibitors in a novel rabbit model of non-occlusive deep vein thrombosis. 802 1

Low molecular weight heparins (LMWHs) are now considered to be the drugs of choice for prophylaxis against deep venous thrombosis (DVT) in post operative patients undergoing both general and orthopaedic surgical procedures. Despite extensive research, the exact mechanism of the antithrombotic activity of LMWHs remains unclear. These agents have been shown to activate the fibrinolytic system and to directly inhibit both the activity and the generation of factor Xa and thrombin. New evidence suggests that LMWHs also stimulate the release of endogenous tissue factor pathway inhibitor (TFPI) from the vascular endothelium. This study was designed to investigate the role of TFPI in mediating the antithrombotic activity of LMWHs. We measured the plasma levels of TFPI in a group of post orthopaedic surgery patients treated with daily subcutaneous injections of LMWH and a group of patients treated with placebo. In the placebo group (n = 25), the plasma TFPI levels were slightly elevated immediately after surgery but returned to their baseline value by the fifth post operative day. In contrast, in the group of patients treated with LMWH (n = 34), the plasma levels of TFPI increased significantly and remained elevated for up to 7 days following surgery. However, the TFPI levels in both groups showed wide patient to patient variability. These results indicate that LMWHs stimulate the release of TFPI into the bloodstream of post surgical patients. This suggests the importance of TFPI in mediating the antithrombotic activity of LMWHs.
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PMID:Role of tissue factor pathway inhibitor in post surgical deep venous thrombosis (DVT) prophylaxis in patients treated with low molecular weight heparin. 802 8

Prevention of deep venous thrombosis is fundamental in the prevention of pulmonary embolism. Deep venous thrombosis is common after all surgical procedures, but the frequency differs, as does the effectiveness of various methods of prevention. Low-dose heparin, low molecular weight heparin, graduated compression elastic stockings, intermittent pneumatic compression, and oral anticoagulants have a role in the prevention of deep venous thrombosis, depending on the risks of deep venous thrombosis and their demonstrated effectiveness (or lack of effectiveness) in the particular circumstance. The optimal method of prophylaxis is specific to the predisposing condition. Heparin continues to be a mainstay of anticoagulant therapy. Major bleeding is rare in patients treated with low doses of heparin to prevent deep venous thrombosis. With therapeutic doses, however, major bleeding occurs in about 5% of patients. The optimal dose of warfarin and the method of evaluating the anticoagulant effect of warfarin have undergone modifications in recent years. It is now recognized that the prothrombin time ratio depends on the activity of the thromboplastin used for measuring the prothrombin time. An International Normalized Ratio, which relates to a standardized thromboplastin, has been developed, thus avoiding differences of the prothrombin time ratio that occur from batch to batch of thromboplastin reagent from the same manufacturer and that occur with different thromboplastin reagents from different animal sources and different manufacturers. The bedside diagnosis of pulmonary embolism is useful in helping a physician determine the extent to which diagnostic tests should be pursued. A sound bedside impression also contributes strongly to the formulation of a noninvasive diagnosis of pulmonary embolism. The clinical manifestations of pulmonary embolism form a recognizable constellation of findings that often lead to a correct diagnosis or exclusion of pulmonary embolism. Important clues to the diagnosis of pulmonary embolism relate to the initial syndrome. The presentation of pulmonary embolism is most often in the form of the pulmonary hemorrhage-pulmonary infarction syndrome. The next most common presentation is unexplained dyspnea, unaccompanied by pulmonary hemorrhage or infarction. Least common, but most severe, is the syndrome of circulatory collapse. Immobilization, usually caused by surgery, is the most frequent predisposing factor. Most patients with clinically recognizable pulmonary embolism have dyspnea or tachypnea. Dyspnea or tachypnea or pleuritic pain occurs in nearly all patients who have clinically apparent pulmonary embolism (97%). Ordinary tests such as the electrocardiogram and chest radiograph are helpful if the physician is attentive to nonspecific abnormalities.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Acute pulmonary embolism. 807

Lysis block treatment (LBT) is a new form of fibrinolytic therapy for deep vein thrombosis and arterial occlusion in the distal parts of the limbs. Strictly local lysis was achieved by placing a cuff around the thigh or the upper arm, inflating the cuff to a pressure of 500 mmHg ("Bier's blockade"), and giving heparin and tissue plasminogen activator (rt-PA) by intravenous injection into the dorsal pedis or antecubital veins. Occlusion lasted for one hour. This new technique was demonstrated in 22 patients. Six patients presented with popliteal vein thromboses and 1 patient with a distal femoral vein thrombosis. In addition, 15 arterial occlusions were treated comprising 3 calf, 6 popliteal, 3 distal femoral, and 2 digital sites and 1 brachial site. Five of 7 venous and 9 of 15 arterial occlusions were partially or totally removed. The activated partial thromboplastin time remained nearly unchanged during LBT and only a limited and short-term lengthening was recorded after restoration of blood flow. This was of importance for patients with bleeding tendencies, which are normally a contraindication for systemic lysis. LBT may therefore be considered as a useful alternative to systemic fibrinolytic treatment.
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PMID:Lysis block treatment: a new form of local thrombolysis. 812 90

Current guidelines for heparin therapy in pediatric patients have been extrapolated from trials in adult patients without rigorous evaluation of efficacy and safety. We prospectively monitored consecutive pediatric patients receiving systemic doses of heparin over 10 mo at one institution using a predetermined nomogram to monitor maintenance therapy. Sixty-five consecutive children; 38 males and 27 females, received systemic doses of heparin. Thirty children had deep venous thrombosis and/or pulmonary embolism; 11 had arterial thrombi, most frequently after diagnostic angiography; and the remaining 24 received heparin prophylactically, for congenital heart disease. Twenty-nine (45%) of the 65 patients were less than 1 y of age and 22 (34%) were 10 y or older. Congenital heart disease was the predominant diagnosis under 1 y and deep venous thrombosis in older children. After a bolus dose of 50 U/kg, 39% of children (n = 30) achieved a minimal level activated partial thromboplastin time (APTT). Sixty-eight percent of children achieved a minimal level APTT by 24 h and 81% by 48 h. For all 65 children, APTT values were within the therapeutic range 43% of the time. APTT values outside the therapeutic range were twice as likely to be low as high. The average amount of heparin required to maintain therapeutic APTT values for children was 22 U/kg/h: 28 U/kg/h for infants < 1 y and 20 U/kg/h for the rest. Bleeding was rare (2%) and mild. Documented recurrent thrombotic disease was more common (7%) with associated morbidity.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Heparin therapy in pediatric patients: a prospective cohort study. 813 3

Low molecular weight heparins are well established in the prophylaxis of deep vein thrombosis in patients with general surgery, in high risk patients undergoing elective hip surgery or emergency surgery and also in patients with an enhanced risk of thrombosis who are treated in medical wards. There are, however, many possibilities for improving prophylaxis and treatment with LMWH. The mechanisms by which low molecular weight heparins and also unfractionated heparin inhibit thrombus formation are not fully understood. The inhibition of thrombin formation and local effects at the endothelial level may be more important than antithrombin-III mediated effects on factor IIa and on factor Xa. For most low molecular weight heparins the most effective dose regimens to be used in patients at high risk have not yet been established. Low molecular weight heparins may be more effective in the treatment of deep venous thrombosis than unfractionated heparin. In the therapeutic studies published so far the major intention was to show that low molecular weight heparins can prevent the progression of deep venous thrombosis and pulmonary embolism to the same extent as unfractionated heparin. Extended treatment regimens, however, may lead to a relevant thrombus reduction. Outpatient treatment for a longer period of time with results not far from those obtained with thrombolysis seem possible especially in elderly patients. Low molecular weight heparins in their present form or modified low molecular weight heparins may be useful for long-term treatment of patients with atherosclerosis with the aim of regression of atherosclerotic lesions. New forms of application, e.g. inhalation, may render long-term treatment more feasible.
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PMID:Low molecular weight heparins--state-of-the-art and unsolved issues. 818 Mar 24

A study of equivalence was performed between two low molecular weight heparins, reviparin-sodium (Clivarin) and enoxaparin (Lovenox) in the prevention of deep vein thrombosis (DVT) after total hip replacement. Nineteen orthopaedic centres participated in the trial. Four hundred and ninety-eight patients were randomized; 247 received reviparin-sodium and 251 enoxaparin; 58 patients were excluded. Each patient received subcutaneous prophylaxis begun 10-12 h pre-operatively and the second injection 10-12 h post-operatively and thereafter every 24 h. In the enoxaparin group 18 DVT were observed (9%); of these 13 (6%) were proximal. In the reviparin-sodium group 21 DVT were observed (10%); 12 (6%) were proximal. The study showed that the efficacy of both LMWHs was equivalent as was the clinical tolerance. There was a slight trend in favour of reviparin-sodium as regards haemoglobin level, and wound haematoma. Anti-factor Xa activity was significantly different despite similar injected doses.
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PMID:Comparison of antithrombotic efficacy and haemorrhagic side-effects of Clivarin versus enoxaparin in patients undergoing total hip replacement surgery. 818 Mar 27


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