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Query: EC:3.4.21.69 (APC)
 16,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The 5-year experience with a panel of laboratory tests designed to identify patients with high risk of thromboembolism was reviewed. This panel included an activated partial thromboplastin time and reptilase time as well as specific assays for antithrombin III, protein C, protein S, and plasminogen. One hundred and nine patients were evaluated by this panel. Conditions predisposing to thrombosis were identified in 24 of these patients and these conditions included: dysfibrinogenemia, lupus anticoagulant, and deficiencies of antithrombin III, protein C and protein S. The limitations of this panel are also discussed.
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PMID:Laboratory identification of conditions predisposing to thrombosis. 214 45

Several reports have appeared on the increased risk of thromboembolic diseases associated with the use of oral contraceptives (OCs). The increased risk of thromboembolism has been related to increased circulating blood levels of certain factors of both the clotting and fibrinolytic systems seen in OC users. These changes have been associated primarily with the estrogen component of the OC preparations. The two new oral contraceptives under study contain reduced levels of ethinyl estradiol, 30 micrograms and each utilizes a new progestogen--75 micrograms gestodene or 150 micrograms desogestrel. A prospective randomized study was performed with 50 women over one year in which several factors of the hemostatic system were investigated; blood samples were taken in treatment cycles 1, 3, 6 and 12 and 6-8 weeks after cessation of therapy. During treatment with both preparations, factors II, VII, IX, X, XI, XII, VIII clotting activity, and prekallikrein were elevated; factor V was not elevated. Antithrombin III which controls these factors, was decreased by 8-10% after 12 months; Protein C which controls factors V and VIII was not changed. Markedly elevated levels of plasminogen and its unaffected inhibitor alpha antiplasmin were seen in the first and all subsequent treatment cycles; this represents increased potency of the lytic system, which can be looked upon as a compensatory mechanism. There were no differences seen between the gestodene and desogestrel preparations regarding changes in the hemostatic system. As with all other low-dose pills, a history of thromboembolism is a contraindication to their use.
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PMID:Influence of modern low-dose oral contraceptives on hemostasis. 214 6

Adults with pulmonary hypertension and polycythemia (N = 22) have low levels of plasma antithrombin III (84 +/- 18 vs 98 +/- 13% for controls, N = 35, P less than 0.005) and protein C (66 +/- 21 vs 125 +/- 30%, N = 8, P less than 0.0002) but normal levels of total protein S. Data are reported as means +/- SD and percent normal values obtained for pooled plasma from normal healthy adults. Children with the same disorder (N = 6) also had low protein C levels (66 +/- 16 vs 85 +/- 5%, P less than 0.025). Total protein S was normal for children, but free protein S was decreased (66 +/- 13 vs 91 +/- 23%, P less than 0.025). Since the levels observed in these patients are above those reported for congenital deficiencies, the reduction in plasma levels of anticoagulant proteins may be the result of chronic intravascular coagulation. Furthermore, normal levels of plasminogen and fibrin degradation products suggest a localized disorder or an acquired decrease in fibrinolytic activity.
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PMID:Plasma anticoagulant system in patients with pulmonary hypertension. 215 Dec 53

The effects of parenterally given polyestradiol phosphate (80 or 160 mg i.m. monthly) and bilateral subcapsular orchiectomy on blood coagulation and fibrinolytic parameters were compared in 11 patients with prostatic carcinoma. Estrogen therapy lowered antithrombin III, plasminogen and plasminogen activator inhibitor activities, whereas these parameters remained unchanged in orchiectomized patients. There were no significant changes in platelet count, fibrinogen, factor VII, protein C and alpha 2-antiplasmin in either group. Estrogen had unfavorable effects on hemostatic laboratory parameters in the direction of a hypercoagulable state. However, no thromboembolic complications were encountered.
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PMID:The effect of parenteral estrogen versus orchiectomy on blood coagulation and fibrinolysis in prostatic cancer patients. 217 41

Recent advances in the understanding of blood coagulation provide strong evidence that exposure of tissue factor is the "match" which initiates blood coagulation. A novel plasma protease inhibitor, called EPI or LACI, effectively extinguishes this "match," leaving Factors IXa, VIII, X, V, and II to function as a "fuse." Activated Factors IX, X, and II are controlled by heparin-enhancable protease inhibitors. Activated Factors VIII and V are destroyed by the protein C/S system. Fibrinolysis is largely cell-based and controlled by differential secretion of plasminogen activators and plasminogen activator inhibitors.
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PMID:Blood coagulation and fibrinolysis: an overview. 219 14

The concept of the haemostatic balance was reviewed, and its potential role in the regulation of tissue repair and the pathogenesis of thrombotic processes was surveyed. Physiological activation of coagulation appears to be dominated by effects of degenerated and injured cells of the vascular wall causing local release of thromboplastin and exposition of activating surfaces. Inhibition of coagulation impairs its progression and the non-thrombogenic nature of the normal endothelium is chiefly caused by the binding of inhibitory components (antithrombin-III, protein C) to specific receptor sites. Physiological activation of fibrinolysis appears to be triggered by and limited to the fibrin because of a specific affinity to fibrin of plasminogen and plasminogen activators. Systemic activation of fibrinolysis is prevented by primary (alpha 2-antiplasmin) and secondary (alpha 2-macroglobulin, alpha 1-antitrypsin) plasmin inhibitors. A plasminogen binding protein (histidine-rich glycoprotein), plasmin inhibitors and activator inhibitors appear to contribute to the regulation of the initial phase of fibrinolysis. A deviation from normal of the dynamic balance, regulating fibrin formation and resolution, may lead to a haemorrhagic and/or a thrombophilic state. Described were the optimization of selected methods for assessment of variables involved in the haemostatic balance. An overestimation of plasminogen concentrations in plasma may occur in patients with elevated levels of fibrinogen or fibrin degradation products, when using assays based on the activation of plasminogen by streptokinase followed by the hydrolysis of a synthetic chromogenic substrate. This source of error could be eliminated by presence of fibrinogen in excess in the plasminogen assay, thereby securing maximum stimulation of the plasminogen-streptokinase complex. The presence of cryoglobulin in plasma interferes with the assessment in euglobulins of plasminogen activator activities. Experiments indicate that tissue-type plasminogen activator adsorb cryoglobulins and that a cold-promoted activation of the factor XII-dependent proactivator system of fibrinolysis is related to the presence of cryoglobulins. Experiments supported the existence of an as yet not characterized factor XII-dependent proactivator. Strictly optimized procedures for the preparation of euglobulins for the accurate determination of plasminogen activators were recommended. The determination of plasminogen activator inhibition in plasma was optimized and simplified. The amidolytic assay of antithrombin-III was shown to be influenced by adsorption to laboratory utensils and aggregation of thrombin. This error could be corrected by protection with additives (Tween 80, polyethyleneglycol 6,000), which also improved the solubility of the chromogenic substrates in aqueous media. The role of thrombosis in myocardial infarction was reviewed.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The haemostatic balance in groups of thrombosis-prone patients. With particular reference to fibrinolysis in patients with myocardial infarction. 219 35

This study, including 33 consecutive patients was designed to assess the haemostatic alterations occurring during repair of thoracoabdominal aneurysms. The surgical procedure consisted in Dacron graft replacement of the diseased aorta, using neither cardiopulmonary bypass, nor any shunting technique, nor any heparin. Blood samples were drawn before anaesthesia, before and 30 min after unclamping, and on the first postoperative day. The measured parameters were: haematocrit, platelet count, bleeding, activated cephalin, thrombin and prothrombin times, and concentrations of fibrinogen, factors V, VII, X and II, anti-thrombin III, proteins C and S, fibrin degradation products, D-dimers, alpha 2-antiplasmin, plasminogen, tissue plasminogen activator, plasminogen activator inhibitor, and serum protein. Eight patients developed severe multiple haemorrhages; 3 of them died during the procedure because of uncontrollable bleeding. Although the measured parameters were similar in the "bleeding" and control (n = 25) groups before surgery, there was, before unclamping in the first group, an important increase in activated cephalin and thrombin times, with a fall in concentrations of factor II and V, protein C, fibrinogen, and alpha 2-antiplasmin, and in platelet numbers. After unclamping, these changes worsened further, with an increase in prothrombin time and in fibrinogen levels (0,8 g.l-1), without any increase in fibrin degradation products. Abnormal bleeding started about 30 min after this in all the patients of the "bleeding" group. These changes, involving the fibrinolytic system as well as a fall in concentration of all the coagulation factors, can probably be partly explained by the clamping and unclamping of mesenteric vessels.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Mechanisms and prediction of hemorrhagic complications during surgery of thoraco-abdominal aortic aneurysms]. 224 Jun 94

In this study, blood coagulation and fibrinolytic parameters were measured in maternal blood and fetal umbilical cord blood in 200 normal pregnant women and in 46 with severe toxemia of pregnancy (Toxemia), and the relationships between fetal growth and concentrations protein C (PC), antithrombin-III (AT-III) and alpha 2-plasmin inhibitor (alpha 2-PI) were studied. 1. Significant increases in fibrin degradation products (FDP) and in plasminogen (Plg), AT-III and PC were found in maternal blood of Toxemia. A significant increase in AT-III and a decrease in alpha 2-PI and PC were observed in cord blood from these patients. 2. The platelet count (Pl) tended to be low in patients with Toxemia complicated by fetal growth retardation (IUGR). 3. Pl and fibrinogen (Fib) tended to be high in Toxemia complicated by normal fetal growth. 4. PC increased from early pregnancy, and a further increase was observed in the puerperium. 5. The PC concentration correlated with the AT-III but not with the alpha 2-PI concentration in maternal blood. 6. PC in cord blood was lower than that in maternal blood, and was correlated with AT-III and alpha 2-PI. 7. In patients with Toxemia, PC was reduced in both maternal and cord blood, and this correlated with AT-III as well as alpha 2-PI in maternal blood. 8. PC was low in Toxemia complicated by hypertension and proteinuria. These results suggest the involvement of FDP, AT-III, PC and Plg in the pathogenesis of Toxemia, and that the Pl, Fib, FDP and alpha 2-PI concentrations are related to fetal growth. Therefore, the PC and AT-III concentrations appeared to be a useful index for the blood coagulation and fibrinolysis in pregnant women and appeared to be important factors in the degree of Toxemia and IUGR.
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PMID:[Blood coagulation and fibrinolytic studies in patients with toxemia of pregnancy]. 227 12

The hemostatic response to acute exercise and increased atmospheric pressure was studied in 20 healthy male subjects (18-35 yr of age) exercised to volitional exhaustion on a cycle ergometer in a hyperbaric chamber at 3 atmospheres absolute (ATA). As a means of comparison, 6 of the 20 subjects were exercised in the same manner at 1 ATA. Similar increases in fibrinolytic activity (FA), Factor VIII activity (VIII:C), von Willebrand factor antigen (vWF:Ag) and plasma catecholamine levels were observed following acute exercise at 1 ATA and at 3 ATA. There were no changes in the levels of plasminogen, antithrombin III, Protein C or Fibrinopeptide A (FPA) with exercise either at 1 ATA or at 3 ATA. In addition, there were no changes in plasma catecholamine levels or any of the hemostatic variables measured when atmospheric pressure was increased from 1 ATA to 3ATA without exercise. These findings demonstrate that increasing atmospheric pressure from 1 ATA to 3 ATA does not alter the exercise-induced changes in hemostasis. Therefore, exercise or physical exertion at 3 ATA for a time period not to exceed 30 min does not perturb the hemostatic mechanism and increase the risk of bleeding or thrombosis.
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PMID:The effects of acute exercise and increased atmospheric pressure on the hemostatic mechanism and plasma catecholamine levels. 233 66

The prevalence and importance of hypercoagulable states in the general vascular surgical population is unknown. Antithrombin III, protein C, protein S, plasminogen, lupus-like anticoagulant, and heparin-induced platelet activation were determined prospectively in 158 patients with aneurysmal (27), renovascular (1), cerebrovascular (28), aortoiliac (31), or infrainguinal (71) disease. Sixteen abnormal test results were obtained in 15 patients (9.5%) as follows: deficiencies of antithrombin III (2), protein C (4), and protein S (1) and presence of lupus-like anticoagulant activity (5) and heparin-induced platelet activation (4). Reconstructive surgery was performed in 137 of the study patients. Five reconstructions, all infrainguinal bypass grafts, suffered thrombosis within 30 days. Early graft thrombosis occurred in three (27%) of 14 patients with abnormal preoperative test results compared to two (1.6%) of 123 patients with normal testing (p less than 0.01). Of the three patients with abnormal test results and graft thrombosis, lupus-like anticoagulant was detected in two and heparin-induced platelet activation in one. This preliminary study supports routine preoperative screening for lupus-like anticoagulant and heparin-induced platelet activation in patients undergoing infrainguinal reconstruction. Hypercoagulable states appear to be sufficiently common and important in the general vascular surgical population to warrant further investigation.
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PMID:Screening for hypercoagulable states in vascular surgical practice: a preliminary study. 235 97


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