| serum prothrombin conversion accelerator | <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) |
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| proserum prothrombin conversion accelerator | 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) |
| prothrombin accelerator | <chemical> Heat- and storage-labile plasma glycoprotein which accelerates the conversion of prothrombin to thrombin in blood coagulation. Factor v accomplishes this by forming a complex with factor xa, phospholipid, and calcium (prothrombinase complex). Deficiency of factor v leads to owren's disease. Chemical name: Blood-coagulation factor V (12 Dec 1998) |
| serum accelerator | <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) |
| serum accelerator globulin | A substance in serum that accelerates the conversion of prothrombin to thrombin in the presence of thromboplastin and calcium; produced by the action of traces of thrombin upon plasma accelerator globulin. (05 Mar 2000) |
| Amine Precursor Uptake and Decarboxylation | <pharmacology, physiology> Paracrine cells of which argentaffin cells are an example. Usage of the term APUD is neither helpful nor memorable. Acronym: APUD (11 Nov 1997) |
| amyloid beta-protein precursor | A precursor to the amyloid-beta protein (beta/a4). Alterations in the expression of the amyloid beta-protein precursor (abpp) gene, located on chromosome 21, plays a role in the development of the neuropathology common to both alzheimer disease and down syndrome. Abpp is associated with the extensive extracellular matrix secreted by neuronal cells. Upon cleavage, this precursor produces three proteins of varying amino acid lengths: 695, 751, and 770. The beta/a4 (695 amino acids) or beta-amyloid protein is the principal component of the extracellular amyloid in senile plaques found in alzheimer disease, down syndrome and, to a limited extent, in normal aging. (12 Dec 1998) |
| amyloid precursor protein | <protein> Individuals with Alzheimer's disease are characterised by extensive accumulation of amyloid in the brain, referred to as senile plaques. These consist of a core of amyloid fibrils surrounded by dystrophic neurites. The principal component of the amyloid fibrils is B/A4, a peptide derived from the larger APP. The specific role of amyloid protein is unclear but it is thought that amyloid deposits may cause neurons to degenerate. Amyloid deposits also occur in brains of older Down's Syndrome patients. (04 May 1997) |
| angiotensin precursor | angiotensin |
| precursor | Something that precedes. 1. <biochemistry> In biological processes, a substance from which another, usually more active or mature substance is formed. 2. In clinical medicine, a sign or symptom that heralds another. Origin: L. Praecursor = a forerunner (18 Nov 1997) |
| enzyme precursor | <biochemistry> Inactive precursors that can be converted to active enzymes. Enzyme precursors containing extra-long polypeptide chains that block activity are activated by acid or enzymatic hydrolysis to remove the inhibiting portion. (12 Dec 1998) |
| prothrombin | Clotting Factor II. Origin: Gr. Thrombos = cloth in (18 Nov 1997) |
| prothrombin and proconvertin test | A test formerly used by some to control anticoagulant therapy with bishydroxycoumarin and indandione drugs. Synonym: P and P test. (05 Mar 2000) |
| prothrombin deficiency | A congenital or acquired disorder of blood clotting where there is a deficiency of factor II (prothrombin), one of 20 necessary plasma proteins for normal blood coagulation. Acquired factor II deficiency may result from vitamin K deficiency, severe liver disease and anticoagulant drugs. Symptoms include abnormal bleeding, nosebleeds, abnormal menstrual bleeding, easy bruising and umbilical cord bleeding at birth. Treatment involves the infusion of fresh frozen plasma. Vitamin K may be administered in select cases. (27 Sep 1997) |
| prothrombin test | A quantitative test for prothrombin in the blood based on the clotting time of oxalated blood plasma in the presence of thromboplastin and calcium chloride; measures the integrity of the extrinsic and common pathways of coagulation. See: prothrombin time. Synonym: Quick's method, Quick's test. (05 Mar 2000) |