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)

In a 2-year-old girl showing purpura on her legs after administration of antibiotics, marked prolongation of activated partial thromboplastin time(APTT) and prothrombin time was noted. Circulating anticoagulants were demonstrated by the failure to correct APTT on neutralization test. A lupus anticoagulant(LA), one of the circulating anticoagulants, was detected by rabbit brain phospholipid neutralization procedure and platelet neutralization procedure. On crossed immunoelectrophoresis, the abnormal prothrombin peaks with reduced electrophoretic mobilities were considered prothrombin/prothrombin-antibody complexes because pretreatment with anti-human IgG serum caused their disappearance. This prothrombin-antibody seemed to be another circulating anticoagulant. The anti-prothrombin-antibody reduced prothrombin activities in the circulating blood of the patient to 20 approximately 30% of normal and the condition persisted for two weeks resulting in the purpura which occurred during that period. After two months, APTT was restored to normal following the disappearance of LA.
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PMID:[Transitions of each inhibitor in a patient with lupus anticoagulant and anti-prothrombin antibody]. 874 1

Hemostatic abnormalities associated with malignancy have been described since the middle of the 19th century. Abnormalities associated with hypercoagulability and hemorrhage are reported in various percentages of patients depending upon the underlying neoplasm and the type of therapy. Changes in the quantitative and qualitative aspects of protein coagulation factors, anticoagulant proteins, circulating anticoagulants, platelets, and vascular responses have been noted. Clinical or subclinical disseminated intravascular coagulopathy (DIC) and associated paradoxical bleeding are common. Hemorrhage may be associated with a decrease of particular coagulation factors or alterations of vascular integrity and platelet numbers or function in various combinations. Evaluation of hemostatic abnormalities associated with cancer (HAAC) includes a careful history and physical examination, assessment of the prothrombin and activated partial thromboplastin times, platelet count, a test for fibrin or fibrinogen degradation products, and assay of fibrinogen levels. Specific findings may suggest the need for tests for naturally occurring protein anticoagulants (e.g., protein S, protein C, and antithrombin III), coagulation inhibitors, abnormalities of the fibrinolytic system, or other esoteric tests. Testing for F1 + 2 and fibrinopeptide A may be useful in determining early activation of prothrombin and thrombin, respectively, and a clue to incipient onset of DIC. Besides the disease, therapies for cancer can alter hemostatic activity. Chemotherapy has been reported to be associated with venous and arterial thromboses, cerebrovascular events, and coagulopathies. Radiation therapy decreases platelet production, particularly if the active bone marrow has been included in the field. Laboratory evaluation of HAAC requires consideration of the type of malignant disorder, the history and physical condition of the patient and any therapy.
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PMID:Hemostatic abnormalities associated with cancer and its therapy. 943 35

Hemostasis is initiated by injury to the vascular wall, leading to the deposition of platelets adhering to components of the subendothelium. Platelet adhesion requires the presence of von Willebrand factor and platelet receptors (IIb/IIIa and Ib/IX). Additional platelets are recruited to the site of injury by release of platelet granular contents, including ADP. The "platelet plug" is stabilized by interaction with fibrinogen. In this review, I consider laboratory tests used to evaluate coagulation, including prothrombin time, activated partial thromboplastin time, thrombin time, and platelet count. I discuss hereditary disorders of platelets and/or coagulation proteins that lead to clinical bleeding as well as acquired disorders, including disseminated intravascular coagulation and acquired circulating anticoagulants.
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PMID:Coagulation and bleeding disorders: review and update. 1092 20

Circulating anticoagulants are endogenously produced substances that interfere with in vitro tests of coagulation like activated partial thromboplastin time (APTT), and cause prolongation of the clotting times. Evaluation of the abnormal APTT involving various factor assays and mixing studies may provide inconclusive and ambiguous results. Tissue thromboplastin inhibition test (TTIT) is one of the screening assays for detection of circulating anticoagulants. However, this test is influenced by the presence of unfractionated heparin (UFH) from concentrations 0.2 U/mL and higher. Since low-molecular-weight heparins (LMWHs) are increasingly used for the prevention of thrombotic disorders and may replace UFH in the future, in this study the authors studied the influence of LMWHs on the performance of TTIT and compared the results with UFH. UFH and LMWHs showed a prolongation of TTIT in the concentration range of 0.25-1.0 U/mL. The marked prolongation of the TTIT with UFH and different LMWHs is in decreasing order of UFH > ardeparin > tinzaparin > dalteparin > enoxaparin. Patients with circulating anticoagulants who are given LMWHs may have false-positive results of TTIT and this influence should be kept in mind during patient management.
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PMID:Differential effects of unfractionated heparin and low-molecular-weight heparins on tissue thromboplastin inhibition test. 1103 May 23

The interpretation of coagulation assays requires knowledge of the principal clotting pathways. The activated partial thromboplastin time is sensitive to all hemostatic factors except FVII, whereas the prothrombin time reflects levels of prothrombin and FV, FVII, and FX. Using the two tests in concert is helpful in identifying hemophilia, the coagulopathy of liver disease, and disseminated intravascular coagulation. In addition, the activated partial thromboplastin time and prothrombin time are used for monitoring anticoagulant therapy with heparin and warfarin, respectively. Measurement of D-dimer is informative in patients suspected of having thrombotic disorders and determining the risk of thrombosis recurrence. Mixing tests distinguish clotting factor deficiencies from circulating anticoagulants such as heparin, the lupus anticoagulant, and antibodies directed against specific clotting factors. The modified Bethesda assay detects and provides an indication of the strength of FVIII inhibitors. However, interpreting the results of coagulation assays is not always straightforward, and expert consultation is occasionally required to resolve difficult clinical situations.
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PMID:Interpreting coagulation assays. 2085 88


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