| rheumatoid factor | Complex of IgG and anti-igG formed in joints in rheumatoid arthritis. Serum rheumatoid factors are more usually formed from IgM antibodies directed against IgG. (18 Nov 1997) |
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| rh factor | An antigen that may or may notbe present on the surface of human bloodcells. If a person's blood has the antigen, their blood type ispositive, if they do not, it is negative. The Rh factor isimportant mainly because if a woman who is Rh- conceives a child who is Rh+, themixing of their bloods in the placenta may provoke an immune reaction in the mother that can cause a life-threatening agglutination of the foetus'blood cells.The Rh factor is so named because it was first identified in Rhesus monkeys. See: ABO blood group. (09 Oct 1997) |
| granulocyte-colony-stimulating factor | <growth factor, haematology, oncology> A glycoprotein of 25 kD containing internal disulfide bonds. It induces the survival, proliferation, and differentiation of neutrophilic granulocyte precursor cells and functionally activates mature blood neutrophils. Among the family of colony-stimulating factors, G-CSF is the most potent inducer of terminal differentiation to granulocytes and macrophages of leukaemic myeloid cell lines. A protein that stimulates the growth and maturation of granulocytes. It is used to promote the recovery of the white cells following chemotherapy. See: colony-stimulating factor. Acronym: G-CSF (12 Dec 1998) |
| granulocyte-macrophage colony-stimulating factor | <growth factor, haematology, oncology> An acidic glycoprotein of mw 23 kD with internal disulfide bonds. It is produced in response to a number of inflammatory mediators by mesenchymal cells present in the haemopoietic environment and at peripheral sites of inflammation. It stimulates the production of neutrophilic granulocytes, macrophages, and mixed granulocyte-macrophage colonies from bone marrow cells and can stimulate the formation of eosinophil colonies from foetal liver progenitor cells. It also has some functional activities in mature granulocytes and macrophages. It is used to promote the recovery of the white blood cells following chemotherapy. Chemical name: Colony-stimulating factor 2 See: colony-stimulating factor. Acronym: GM-CSF (12 Dec 1998) |
| rho factor | <cell biology> Protein factors found in prokaryotes, especially E. Coli, involved in the termination of transcription. Mutations in rho may cause the RNA polymerase to read through from one operon to the next. (23 Aug 1998) |
| mesodermal factor | A protein that can induce the formation of kidney and muscle primordia in embryos. (05 Mar 2000) |
| risk factor | <statistics> A clearly defined occurrence or characteristic that has been associated with the increased rate of a subsequently occurring disease. (14 Oct 1997) |
| Christmas factor | <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) |
| christmas factor assay | A test used to measure the activity of a blood clotting factor IX (Christmas factor). This test may be used to evaluate excessive bleeding. Abnormally low factor IX assays may be seen in the following conditions: congenital deficiency of factor IX, fat malabsorption, heparin administration, cirrhosis, vitamin K deficiency and warfarin administration. (27 Sep 1997) |
| ciliary neurotrophic factor | <growth factor> Neurotrophic factor originally characterised as a survival factor for chick ciliary neurons in vitro. Subsequently shown to promote the survival of a variety of other neuronal cell types and to promote the differentiation of bipotential O2A progenitor cells to type 2 astrocytes in vitro. Molecular cloning and expression studies indicate that CNTF is a cytosolic protein. Developmental expression and regional distribution studies show that, unlike NGF, CNTF is not a target derived neurotrophic factor. (18 Nov 1997) |
| migration-inhibitory factor | <growth factor> A soluble, nondialysable factor that is produced by sensitised lymphocytes following exposure to a specific antigen. It inhibits macrophage migration and causes adherence. It was originally defined on the basis of inhibition of emigration of mononuclear cells from capillary (haematocrit) tubes, more recently a 13 kD protein with migration inhibitory activity has been isolated. Acronym: MIF Synonym: inhibition factor. (22 Sep 2002) |
| migration-inhibitory factor test | A test which measures the presence of migration-inhibitory factor. Usually peritoneal macrophages are placed in a capillary tube in the presence or absence of supernatants from activated T-cells. If MIF is present, the migration of monocyte/macrophages is reduced. Synonym: macrophage migration inhibition test, migration inhibition test. (05 Mar 2000) |
| citrovorum factor | N5Formyl-5,6,7,8-tetrahydrofolic acid;the active form of folic acid which acts as a formyl group carrier in transformylation reactions; the calcium salt, leucovorin calcium, has therapeutic use. Synonym: citrovorum factor, leucovorin. (05 Mar 2000) |
| milk factor | Member of the retrovirus subfamily Oncornavirinae, antigenically distinct from the murine leukaemia-sarcoma complex, that is associated with adenocarcinomatous tumours of the mammary gland, commonly latent in wild and laboratory mice and causing cancer only in genetically susceptible strains under certain hormonal influences. Synonym: Bittner agent, Bittner virus, Bittner's milk factor, mammary cancer virus of mice, milk factor, mouse mammary tumour virus. (05 Mar 2000) |
| clotting factor | <haematology> A group of chemical constituents of the blood (factors I to XIII) which interact to make the blood clot. (13 Nov 1997) |