| tumour necrosis factor | <cytokine> Originally described as a tumour inhibiting factor in the blood of animals exposed to bacterial lipopolysaccharide or Bacille Calmette-Guerin. Preferentially kills tumour cells in vivo and in vitro, causes necrosis of certain transplanted tumours in mice and inhibits experimental metastases. Human Tumour Necrosis factor alpha is a protein of 157 amino acids and has a wide range of pro inflammatory actions. Usually considered a cytokine. Synonym: cachectin. Acronym: TNF (13 Nov 1997) |
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| tumour necrosis factor-beta | <cytokine> A cytolytic factor that is produced by CD4 and CD8 T-cells after their exposure to an antigen. (05 Mar 2000) |
| extinction factor | <microscopy> In a polarizing or Differential Interference Contrast microscope, the ratio of the amount of light that is transmitted with the axes of the polars parallel over the amount transmitted with their axes crossed. Unless the lenses are rectified, the extinction factor drops exponentially as the numerical aperture is increased. Acronym: EF (26 Mar 1998) |
| extrinsic factor | Dietary vitamin B12. (05 Mar 2000) |
| extrinsic factor deficiency | <disease> 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) |
| keratinocyte growth factor | <growth factor> A growth factor structurally related to fibroblast growth factor. (18 Nov 1997) |
| fermentation Lactobacillus casei factor | Pteroyl-gamma-glutamyl-gamma-glutamylglutamic acid;a folic acid conjugate, a principle chemically similar to folic acid except that it contains three molecules of glutamic acid instead of one, in g linkage. Synonym: fermentation Lactobacillus casei factor, pteroyltriglutamic acid. (05 Mar 2000) |
| fertility factor | The prototype conjugative plasmid associated with conjugation in the K-12 strain of Escherichia coli. Synonym: F agent, F-factor, F genote, F-genote, fertility agent, fertility factor, sex factor. (05 Mar 2000) |
| F-factor | <molecular biology> A small piece of episomal bacterial DNA (plasmid) which provides bacteria with the ability to initiate conjugation (bacterial mating) with other nearby bacteria. It can be present as extrachromosomal protein or integrated into the bacterial chromosome, and effectively determines the 'sex' of the bacterium, host chromosome mobilization, transfer via conjugation of genetic material, and the formation of sex pili. During conjugation, the F-factor is copied and passed on to the other bacterium so that it acquires the ability to initiate conjugation also. (12 Jul 2000) |
| fibrin-stabilizing factor | <chemical> Fibrin stabilizing factor. It is a glycoprotein activated by thrombin in the presence of calcium to form factor xiiia. Factor xiii is found evenly distributed between plasma and platelets. Its function is to stabilise the formation of the fibrin polymer (clot) which culminates the coagulation cascade. Chemical name: Blood-coagulation factor XIII (12 Dec 1998) |
| fibroblast growth factor | <growth factor> Acidic fibroblast growth factor (alpha FGF, HBGF 1) and basic FGF (beta FGF, HBGF 2) are the two founder members of a family of structurally related growth factors for mesodermal or neuroectodermal cells. Synonym: heparin binding growth factor. Acronym: FGF (18 Nov 1997) |
| fibroblast growth factor, acidic | <chemical> A growth factor which has been isolated from a variety of cells. It contains 154 amino acid residues and has potent heparin-binding activity. Heparin potentiates the biological activities of afgf. The growth factor is an extremely potent inducer of DNA synthesis in a variety of normal diploid mammalian cell types from mesoderm and neuroectoderm lineages and also has chemotactic and mitogenic activities. Chemical name: Fibroblast growth factor (human brain acidic protein moiety reduced) (12 Dec 1998) |
| fibroblast growth factor, basic | A single-chain polypeptide of approximately 15-16 kD which has been isolated from a variety of cells. It has a 55% amino acid residue identity to acidic fibroblast growth factor and has potent heparin-binding activity. However, in contrast to the acidic fibroblast growth factor, heparin does not potentiate the biological activities of bfgf. The growth factor is an extremely potent inducer of DNA synthesis in a variety of normal diploid mammalian cell types from mesoderm and neuroectoderm lineages and promotes cellular differentiation in vitro. (12 Dec 1998) |
| fibroblast growth factor receptor | Family of receptor tyrosine kinases for fibroblast growth factor. (18 Nov 1997) |
| fibroblast growth factor receptor-like embryonic kinase | <enzyme> Found in avian embryonic tissue; involved in early differentiation of skeletal muscle. Registry number: EC 2.7.1.- Synonym: frek (26 Jun 1999) |