| factor | <pharmacology> Any of several substances or activities that are necessary to produce a result, for example a coagulation factor. Often, use of the term factor indicates that the chemical nature of the substance or its mechanism of action is unknown, as in endocrinology, where factors are renamed as hormones when their chemical nature is determined. (18 Nov 1997) |
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| factor 3 | Operational name given to an incompletely characterised selenium-containing natural product which, in minute amounts, prevents liver damage in rats due to deficiency of vitamin E, factor III in the vitamin B12 series, 5-hydroxybenzimidazole, analogue of the usual B12 nucleotide components. (05 Mar 2000) |
| factor A | A component of the properdin system; a hydrazine-sensitive b1-globulin (mw about 180,000), now known to be C3 (third component of complement). (05 Mar 2000) |
| factor analysis, statistical | A set of statistical methods for analyzing the correlations among several variables in order to estimate the number of fundamental dimensions that underlie the observed data and to describe and measure those dimensions. It is used frequently in the development of scoring systems for rating scales and questionnaires. (12 Dec 1998) |
| factor B | <enzyme> A glycine-rich, heat-labile beta-glycoprotein found in blood. It is a proactivator of complement 3 in the alternate pathway of complement activation. Factor b is converted by factor d to c3 convertase. Registry number: EC 3.4.21.47 (12 Dec 1998) |
| factor D | <enzyme> A serum protein which during the alternate pathway of complement activation converts the inactive properdin factor b to c3 convertase. Registry number: EC 3.4.21.46 (12 Dec 1998) |
| factor E | A serum protein (mw 160,000) required for activation of C3 (third component of complement) by cobra venom factor. See: properdin system. (05 Mar 2000) |
| factor Gm | A factor that determines certain of the allotypes of human immunoglobulins; found only on the g chains of IgG (gamma-globulin). (05 Mar 2000) |
| factor H | Former designation for biotin, vitamin B12 analogue or precursor, a glycoprotein that regulates the activity of complement factor C3b; a deficiency results in the lack of inhibition of the alternative haemolytic pathway leading to continuous activation and consumption of factor C3 (haemolytic uraemic syndrome). (05 Mar 2000) |
| factor I | <haematology> A protein which is synthesised by the liver. Fibrinogen is converted to fibrin, in the formation of a blood clot, via the enzymatic action of thrombin. A fibrinogen assay measures the concentration of fibrinogen in the blood and may be used to evaluate abnormal blood clotting. A lack of fibrinogen may be congenital or acquired. A condition known as DIC results in the excessive utilisation and depletion of fibrinogen. Synonym: fibrinogen. (15 Nov 1997) |
| factor II | <haematology> A protein which is synthesised by the liver. Fibrinogen is converted to fibrin, in the formation of a blood clot, via the enzymatic action of thrombin. A fibrinogen assay measures the concentration of fibrinogen in the blood and may be used to evaluate abnormal blood clotting. A lack of fibrinogen may be congenital or acquired. A condition known as DIC results in the excessive utilisation and depletion of fibrinogen. Synonym: thrombin. (15 Nov 1997) |
| factor II assay | A test used to measure the activity of a blood clotting factor (thrombin). This test may be used to evaluate excessive bleeding. Abnormally low factor II assays may be seen in the following conditions: congenital deficiency of factor II, fat malabsorption, heparin administration, cirrhosis, vitamin K deficiency and warfarin administration. (27 Sep 1997) |
| factor II 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) |
| factor IIa | <enzyme> Protease (34 kD) generated in blood clotting that acts on fibrinogen to produce fibrin. Consists of two chains, A and B, linked by a disulphide bond. B chain has sequence homology with pancreatic serine proteases: cleaves at Arg Gly. Thrombin is produced from prothrombin by the action either of the extrinsic system (tissue factor + phospholipid) or, more importantly, the intrinsic system (contact of blood with a foreign surface or connective tissue). Both extrinsic and intrinsic systems activate plasma factor X to form factor Xa which then, in conjunction with phospholipid (tissue derived or platelet factor 3) and factor V, catalyses the conversion. (18 Nov 1997) |
| factor III | In the clotting of blood, tissue factor or thromboplastin; it initiates the extrinsic pathway by reacting with factor VII and calcium to form factor VIIa. See: thromboplastin. (05 Mar 2000) |
| accelerator factor | <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) |
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| acetate replacement factor | <biochemistry> 1,2 dithiolane 3 valeric acid. Regarded as a coenzyme in the oxoglutarate dehydrogenase complex of the citric acid cycle. Involved generally in oxidative decarboxylations of _ keto acids. A growth factor for some organisms. (18 Nov 1997) |
| adrenal weight factor | A postulated substance of adenohypophysial origin responsible for maintenance of the weight of the adrenal cortex. (05 Mar 2000) |
| adrenocorticotropic releasing factor | Hormone produced by hypothalamus that causes pituitary to secrete adrenocorticotropic hormone. (05 Mar 2000) |
| a-factor | <molecular biology> A protein which is found in the bacterial genus Streptomyces that helps start the production of streptomycin and the process of morphological differentiation. It is used in biotechnology to induce these functions in mutant strains of Streptomyces that cannot produce it themselves. (09 Feb 1998) |
| angiogenesis factor | Substance causing proliferation of new blood vessels. It is found in tissues with high metabolic requirements, such as the retina, and in certain cancers. The factor is also released by hypoxic macrophages at the edges or outer surfaces of wounds and initiates revascularization in wound healing. (12 Dec 1998) |
| animal protein factor | <biochemistry> Member of the water soluble B vitamin group, important in the proper function of the nervous system and important in proper carbohydrate, protein and fat metabolism. (27 Sep 1997) |
| antialopecia factor | A member of the vitamin B complex necessary for growth of yeast and of mice, absence from the diet causes hair loss and dermatitis in mice. (27 Sep 1997) |
| antianaemic factor | <biochemistry> Member of the water soluble B vitamin group, important in the proper function of the nervous system and important in proper carbohydrate, protein and fat metabolism. (27 Sep 1997) |
| antiberiberi factor | Synonym: thiamin. (05 Mar 2000) |
| anti-black-tongue factor | A precursor of NAD, that is a product of the oxidation of nicotine. (18 Nov 1997) |
| anticomplementary factor | A factor that interferes with the action or function of complement. (05 Mar 2000) |
| antidermatitis factor | <chemical> Chemical name: beta-Alanine, N-(2,4-dihydroxy-3,3-dimethyl-1-oxobutyl)-, (R)- (12 Dec 1998) |
| antihemophilic factor A | 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) |
| antihemophilic factor B | <chemical> Storage-stable blood coagulation factor acting in the intrinsic pathway. Its activated form, ixa, forms a complex with factor viii and calcium on platelet factor 3 to activate factor x to xa. Deficiency of factor ix results in christmas disease (haemophilia b). Chemical name: Blood-coagulation factor IX (12 Dec 1998) |