| antitermination factor | <molecular biology> A gene regulatory protein that blocks signals for the transcription process to stop as a form of regulatory control over whatever the gene being transcribed is coding for. (13 Jan 1998) |
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| atrial natriuretic factor | <chemical> A potent natriuretic and vasodilatory peptide or mixture of different-sized low molecular weight peptides derived from a common precursor and secreted by the heart atria. All these peptides share a sequence of about 20 amino acids. Chemical name: Atriopeptin (12 Dec 1998) |
| attenuation factor | <radiobiology> A measure of the opacity of a layer of material for radiation transversing it, the ratio of the incident intensity to the transmitted intensity. It is equal to Io/I, where Io and I are the intensities of the incident and emergent radiation, respectively. In the usual sense of exponential absorption (I = Ioe- m x), the attenuation factor is e- m x, where x is the thickness of the material and m is the absorption coefficient. (16 Dec 1997) |
| autocrine motility factor | A member of the class of cytokines secreted by tumour cells. It elicits increases in cell motility and phosphoinositide metabolism in the secreting or producing cell via a pertussis toxin-sensitive g-protein signal transduction pathway. The factor has also been used as a marker for bladder cancer. (12 Dec 1998) |
| B-cell differentiating factor | <cytokine> A soluble cytokine factor produced by activated T-lymphocytes that promotes antibody production by causing proliferation and differentiation of B-cells. Interleukin-4 induces the expression of class II major histocompatibility complex and fc receptors on B-cells. It also acts on T-lymphocytes, mast cell lines, and several other haematopoietic lineage cells including granulocyte, megakaryocyte, and erythroid precursors, as well as macrophages. Acronym: IL-4 (12 Dec 1998) |
| B-cell stimulatory factor 2 | <cytokine> A cytokine that stimulates the growth and differentiation of human B-cells and is also a growth factor for hybridomas and plasmacytomas. It is produced by many different cells including T-cells, monocytes, and fibroblasts. A single chain 25 kD cytokine originally described as a pre B-cell growth factor, now known to have effects on a number of other cells including T-cells which are also stimulated to proliferate. An inducer of acute phase proteins and a colony-stimulating factor acting on mouse bone marrow. Acronym: IL-6 (12 Dec 1998) |
| bifidus factor | An unidentified substance associated with Lactobacillus bifidus subsp. Pennsylvanicus, present in mammalian milk. (05 Mar 2000) |
| bioaccumulation factor | Concentration of a chemical in living tissue divided by its concentration in the animal's diet. (09 Oct 1997) |
| bioconcentration factor | Concentration of a chemical in an organism divided by its concentration in the test solution or environment (for example, concentration in fish divided by concentration in water). (09 Oct 1997) |
| Bittner's 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) |
| blood clotting factor | <haematology> Any of a number of different protein factors which, when acting together, can form a blood clot shortly after platelets have broken at the site of the wound. The factors have Roman numeral names, like VII, VIII, IX, X, XI, and XIII. Defects in the genes which code for any of these factors result in genetic diseases like haemophilia, which results from a defect in the gene for factor VIII or IX. (09 Oct 1997) |
| blood coagulation factor inhibitors | Substances, usually endogenous, that act as inhibitors of blood coagulation. They may affect one or multiple enzymes throughout the process. As a group, they also inhibit enzymes involved in processes other than blood coagulation, such as those from the complement system, fibrinolytic enzyme system, blood cells, and bacteria. (12 Dec 1998) |
| brain-derived neurotrophic factor | <growth factor> Small basic protein purified from pig brain, a member of the family of neurotrophic factors that also includes Nerve Growth Factor and neurotrophin 3. In contrast to nerve growth factor, brain-derived neurotrophic factor is predominanantly (though not exclusively) localised in the CNS. It supports the survival of primary sensory neurons originating from the neural crest and ectodermal placodes that are not responsive to NGF. In the brain brain-derived neurotrophic factor has a trophic action on retinal, cholinergic, and dopaminergic neurons, and in the peripheral nervous system it acts on both motor and sensory neurons. Acronym: BDGF (12 Dec 1998) |
| branching factor | 1,4-alpha-glucan-branching enzyme. (05 Mar 2000) |
| BT factor | <biochemistry> _ Hydroxy _ trimethyl aminobutyric acid. Compound that transports long chain fatty acids across the inner mitochondrial membrane in the form of acyl carnitine. Sometimes referred to as Vitamin Bt or Vitamin B7. (18 Nov 1997) |