| S factor | The individual variables, or empirically most minute subclusters of intercorrelations or common variance, found in different intelligence tests (specific). (05 Mar 2000) |
|---|---|
| sigma factor | Initiation factor (86 kD) that binds to E. Coli DNA dependent RNA polymerase and promotes attachment to specific initiation sites on DNA. Following attachment, the sigma factor is released. (18 Nov 1997) |
| hyperglycaemic-glycogenolytic factor | A polypeptide hormone (3485 D) secreted by the cells of the Islets of Langerhans in response to a fall in blood sugar levels. Induces hyperglycaemia. A family of structurally related peptides includes glucagon like peptides 1 & 2 (encoded by the same gene), gastric inhibitory polypeptide, secretin, vasoactive intestinal peptide, growth hormone releasing factor, pituitary adenylate cyclase activating polypeptide, exendins. (18 Nov 1997) |
| slow-reacting factor of anaphylaxis | Slow-reacting substance of anaphylaxis (SRS-A), a leukotriene of low molecular weight which is released in anaphylactic shock and produces slower and more prolonged contraction of muscle than does histamine; it is active in the presence of antihistamines (but not epinephrine) and seems not to occur preformed in mast cells, but as a result of an antigen-antibody reaction on the granules. Compare: peptidyl leukotrienes. Synonym: slow-reacting factor of anaphylaxis. (05 Mar 2000) |
| somatotropin release-inhibiting factor | <protein> Gastrointestinal and hypothalmic peptide hormone (two forms: 14 and 28 residues), found in gastric mucosa, pancreatic islets, nerves of the gastrointestinal tract, in posterior pituitary and in the central nervous system. Inhibits gastric secretion and motility: in hypothalamus/pituitary inhibits somatotropin release. (18 Nov 1997) |
| somatotropin-releasing factor | A decapeptide released by the hypothalamus, which induces the release of human growth hormone (somatotropin). Synonym: growth hormone-releasing factor, growth hormone-releasing hormone, somatotropin-releasing factor, somatotropin-releasing hormone. Origin: somatotropin + L. Libero, to free, + -in (05 Mar 2000) |
| spreading factor | <enzyme> Enzyme that degrades hyaluronic acid, found in lysosomes. (18 Nov 1997) |
| stable factor | <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) |
| Steel factor | Murine equivalent of stem cell factor. (18 Nov 1997) |
| stem cell factor | <growth factor> Haemopoietic growth factor 18.6 kD from sequence, found as dimer (35 kD protein, 53 kD in its glycosylated form). Acronym: SCF (18 Nov 1997) |
| nephritic factor | A serum protein (possibly an IgG autoantibody), found in some patients with membranoproliferative glomerulonephritis and hypocomplementemia, which, together with the cofactors of the alternate pathway of complement activation, cleaves the third component of complement (C3). (05 Mar 2000) |
| nerve growth factor | <growth factor> A peptide (13.26 kD) of 118 amino acids (usually dimeric) with both chemotropic and chemotrophic properties for sympathetic and sensory neurons. Found in a variety of peripheral tissues, nerve growth factor attracts neurites to the tissues by chemotropism, where they form synapses. The successful neurons are then protected from neuronal death by continuing supplies of nerve growth factor. It is also found at exceptionally high levels in snake venom and male mouse submaxillary salivary glands, from which it is commercially extracted. Nerve growth factor was the first of a family of nerve tropic factors to be discovered. Amino acids 1-81 show homology with proinsulin. Besides its peripheral actions, nerve growth factor selectively enhances the growth of cholinergic neurons that project to the forebrain and that degenerate in Alzheimer's disease. Acronym: NGF (18 Nov 1997) |
| nerve growth factor antiserum | An antiserum containing antibodies against nerve growth factor; when injected into newborn animals the majority of sympathetic ganglion cells are permanently destroyed, resulting in hypoinnervation of peripheral tissues. Synonym: NGF antiserum. (05 Mar 2000) |
| neural factor | A protein that can induce the formation of notochord tissue in embryos. (05 Mar 2000) |
| neurotrophic factor | A molecule, usually a protein, that will facilitate the growth or repair of nerve cells. (14 Nov 1997) |