| factor V1a | The hexa-amide of cobyrinic acid; a part of the vitamin B12 structure. Synonym: cobyrinamide, cobyrinic hexa-amide, factor V1a. (05 Mar 2000) |
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| factor va | <chemical> Activated form of factor v. It is an essential cofactor for the activation of prothrombin catalyzed by factor xa. Chemical name: Blood-coagulation factor Va (12 Dec 1998) |
| factor v assay | A test used to measure the activity of a blood clotting factor V. This test may be used to evaluate excessive bleeding. Abnormally low factor V assays may be seen in the following conditions: congenital deficiency of factor V, DIC, heparin administration, cirrhosis and primary fibrinolysis. (27 Sep 1997) |
| factor v deficiency | An inherited disorder that results in abnormal blood clotting due to the deficiency of factor V, one of 20 plasma proteins responsible for the maintenance of normal blood clotting. Symptoms include excessive bleeding, bleeding gums, nosebleeds, easy bruising, excessive menstrual bleeding and bleeding into muscle tissue (haematoma) or a joint space (haemarthrosis). Treatment includes the infusion of fresh frozen plasma to restore deficient factor V. (27 Sep 1997) |
| factor vii | <chemical> Heat- and storage-stable plasma protein that is activated by tissue thromboplastin to form factor viia in the extrinsic pathway of blood coagulation. The activated form then catalyses the activation of factor x to factor xa. Chemical name: Blood-coagulation factor VII (12 Dec 1998) |
| factor viia | <enzyme> Activated form of factor vii. Factor viia activates factor x in the extrinsic pathway of blood coagulation. Registry number: EC 3.4.21.21 (12 Dec 1998) |
| factor vii assay | A test used to measure the activity of a blood clotting factor VII. This test may be used to evaluate excessive bleeding. Abnormally low factor VII assays may be seen in the following conditions: congenital deficiency of factor VII, fat malabsorption, heparin administration, cirrhosis, vitamin K deficiency and warfarin administration. (27 Sep 1997) |
| factor vii deficiency | An inherited disorder that causes abnormal blood clotting due to the congenital absence of one of the 20 different plasma proteins involved in the coagulation process. Symptoms include bleeding of the gums, nosebleeds, easy bruising, bleeding in muscles or joints and excessive menstrual bleeding. Treatment includes the administration of plasma concentrates of factor VII (extrinsic factor). (27 Sep 1997) |
| factor viii | A coagulation (clotting) factor. Classic haemophilia (haemophilia A) is due to a congenital deficiency in the amount (or activity) of factor VIII. Factor VIII is also known as antihemophiliac factor (AHF) or antihemophiliac globulin (AHG). The gene for factor VIII (that for classic haemophilia) is on the X chromosome so females can be silent carriers without symptoms and males can be haemophiliacs. (12 Dec 1998) |
| factor viiia | <chemical> Activated form of factor viii. The b-domain of factor viii is proteolytically cleaved by thrombin to form factor viiia. Factor viiia exists as a non-covalent dimer in a metal-linked (probably calcium) complex and functions as a cofactor in the enzymatic activation of factor x by factor ixa. Factor viiia is similiar in structure and generation to factor va. Chemical name: Blood-coagulation factor VIIIa, procoagulant (12 Dec 1998) |
| factor viii assay | A test used to measure the activity of a blood clotting factor VIII (Von Willebrand factor). This test is usually used to monitor treatment of haemophilia. Abnormally low factor VIII assays may be seen in the following conditions: congenital deficiency of factor VIII (haemophilia), DIC and secondary fibrinolysis. This test may also be performed in the evaluation of Von Willebrand's disease. (27 Sep 1997) |
| factor viii deficiency | A sex-linked genetic disease affecting males that results from a deficiency of clotting factor VIII, a protein factor that is required for normal blood coagulation. Symptoms include easy bruising, bleeding gums, nosebleeds and bleeding into muscle tissue (haematoma) or a joint space (haemarthrosis). Treatment includes the infusion of factor VIII concentrate intravenously to restore this essential factor and normalize blood coagulation. Inheritance: sex-linked. (27 Sep 1997) |
| factor x | <chemical> Storage-stable glycoprotein blood coagulation factor that can be activated to factor xa by both the intrinsic and extrinsic pathways. A deficiency of factor x, sometimes called stuart-prower factor deficiency, may lead to a systemic coagulation disorder. Chemical name: Blood-coagulation factor X (12 Dec 1998) |
| factor xa | <enzyme> Activated form of factor x that participates in both the intrinsic and extrinsic pathways of blood coagulation. It catalyses the conversion of prothrombin to thrombin in conjunction with other cofactors. Registry number: EC 3.4.21.6 (12 Dec 1998) |
| factor x assay | A test used to measure the activity of a blood clotting factor X. This test may be used to evaluate excessive bleeding. Abnormally low factor X assays may be seen in the following conditions: congenital deficiency of factor X, fat malabsorption, heparin administration, cirrhosis, vitamin K deficiency and warfarin administration. (27 Sep 1997) |