Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.6 (thromboplastin)
 13,278 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Clinical observations have added to the understanding of basic mechanisms of blood coagulation and its alterations in certain hemorrhagic and thrombotic states. Much clinical evidence exists for concluding that the exposure of blood to tissue factor (thromboplastin) on tissue cells represents the key event initiating fibrin clot formation after tissue injury. This then results in the formation of activated factor VII (VIIa)-tissue factor complexes, which must activate both factor X and factor IX for normal hemostasis. I describe the possible clinical consequences of an aberrant function of the natural anticoagulants regulating blood coagulation--antithrombin, protein C, and tissue factor pathway inhibitor. Understanding the physiologic function of tissue factor pathway inhibitor can illuminate why hemophilic patients bleed, but many other questions remain. I briefly review the four causes for acquired disorders of the blood coagulation reactions--vitamin K deficiency, hepatocellular disease, antibodies to clotting factors, and disseminated intravascular coagulation--but limit my comments to the mechanisms that trigger the formation of antibodies to clotting factors and how these antibodies can deplete the blood of clotting factor activities. Finally, heparin is able to potentiate tissue factor pathway inhibitor function, which is a possible reason why the use of heparin but not warfarin can prevent the numerous thrombotic episodes of the Trousseau's syndrome.
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PMID:Blood coagulation and its alterations in hemorrhagic and thrombotic disorders. 843 80

Trousseau's syndrome (cancer-associated thrombosis) is the second leading cause of death in cancer patients, after death from cancer itself. The risk of a venous thromboembolism is 4- to 7-fold higher in patients with cancer than in those without cancer. The causes of this impaired coagulation are associated with general patient-related risk factors, and other factors that are specific to the particular cancer or treatment. It is important to assess the risk of thrombotic events in cancer patients and administer effective prophylaxis and treatment. Effective prophylaxis and treatment of venous thromboembolism reduces morbidity and mortality, and improves patients' quality of life. Low molecular weight heparin is the first-line treatment for venous thromboembolism, as an effective and safe means for prophylaxis and treatment, according to guidelines released by international scientific societies. Oral anticoagulation therapy with warfarin is preferable to no therapy. However, warfarin has low efficacy and is associated with high rates of recurrence. If low molecular weight heparin is unavailable, some guidelines recommend the use of vitamin K antagonists that have a target international normalized ratio in the range of 2-3, as acceptable alternatives. Novel oral anticoagulants that directly inhibit factor Xa or thrombin are promising for the prophylaxis of high-risk cancer patients and in the long-term treatment of venous thromboembolism. However, to date, there is insufficient evidence to support the use of these new anticoagulants.
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PMID:Trousseau's syndrome: cancer-associated thrombosis. 2654 90