| structure-activity relationship | The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups. Other factors contributing to structure-activity relationship include chemical reactivity, electronic effects, resonance, and inductive effects. (12 Dec 1998) |
|---|---|
| nonsuppressible insulin-like activity | A blood protein (nsila) which mimics the biological activity of insulin in serum, but is not suppressed by insulin antibodies. During acid-ethanol extraction of cohn fraction III, 10% of the activity is found in the supernatant (nsila-s) and the remaining activity in the precipitate (nsila-p). The latter is a large molecular compound, much less stable than the soluble fraction. Nsila-s is a more potent growth factor than insulin and exhibits sulfation activity. (12 Dec 1998) |
| drug activity | A measure of the physiological response a drug produces. A less active drug produces less response (and visa versa). (12 Dec 1998) |
| insulin-like activity | A measure of substances, usually in plasma, that exert biologic effects similar to those of insulin in various bioassays; sometimes used as a measure of plasma insulin concentrations; always gives higher values than immunochemical techniques for the measurement of insulin. (05 Mar 2000) |
| intrinsic sympathomimetic activity | The property of a drug that causes activation of adrenergic receptors so as to produce effects similar to stimulation of the sympathetic nervous system. (05 Mar 2000) |
| optical activity | The ability of a material to rotate the plane of polarized light. (09 Oct 1997) |
| triggered activity | One or a series of spontaneously generated heart beats originating from an action potential that produces an after-depolarisation which reaches activation threshold. (05 Mar 2000) |
| unit of thyrotrophic activity | The activity of an amount of an extract of the anterior lobe of the hypophysis which, given daily for 5 days, will cause the thyroid of a guinea pig (weighing 200 g) to reach a weight of 600 mg. (05 Mar 2000) |
| zone of polarizing activity | <cell biology> The small group of mesenchyme cells in avian limb buds that is located at the posterior margin of the developing bud and that produces a substance, possibly retinoic acid, that provides positional information to the developing limb bud. (18 Nov 1997) |
| bis-gamma-glutamylcystine reductase | <enzyme> From halobacterium halobium; specific for NADPH Registry number: EC 1.6.4.- Synonym: bis-ggc reductase (26 Jun 1999) |
| gamma | <physics> Third letter in the Greek alphabet, variable used for a number of things in physics, in plasma physics gamma is often used as the variable for growth rates of instabilities. (09 Oct 1997) |
| gamma-Abu | gamma-aminobutyric acid |
| gamma alcoholism | Jellinek's term for a severe stage of alcoholism characterised by a progression from psychological to physiological dependence upon alcohol, including tissue dependence and withdrawal symptoms, with loss of control over alcohol intake and destructive effects on interpersonal relationships. (05 Mar 2000) |
| gamma aminobutyric acid | <biochemistry> An important amino acid which functions as the most prevalent inhibitory neurotransmitter in the central nervous system. Gamma aminobutyric acid works in partnership with a derivative of Vitamin B-6, pyridoxine, to cross from the axons to the dendrites through the synaptic cleft, in response to an electrical signal in the neuron and inhibits message transmission. This helps control the nerve cells from firing too fast, which would overload the system. The action of gamma aminobutyric acid decreases epileptic seizures and muscle spasms by inhibiting electrical signals in this manner. Studies have shown that the site of action in the brain of benzodiazepams, including Valium, is directly coupled to the brain receptor for gamma aminobutyric acid. Acronym: GABA (05 Jan 1998) |
| gamma aminobutyric acid receptor | <physiology> Ligand gated chloride ion channel forming receptor opened by gamma aminobutyric acid. Two distinct types: A and B. A receptor: One of a family of neurotransmitter receptors with fast intrinsic ion channels that includes the glycine receptor and the nicotinic acetylcholine receptor. Distinct from another major receptor family, the muscarininc acetylcholine receptor and rhodopsin, with no intrinsic ion channel. The A receptor is specifically blocked by bicuculline. It consists of two pairs of protein chains forming an A2B2 complex, the A chains bind benzodiazepine and the B chains bind GABA. The 4 subunits are thought to form a tight group with the chloride channel in the middle. There is considerable similarity between the amino acid sequences of the receptor subunits and those of the nicotinic acetylcholine receptor suggesting that both receptors are derived from some evolutionary ancestor. See: amino acid receptor superfamily. B receptor: Brain receptor (80 kD) for the inhibitory neurotransmitter gamma amino butyric acid. Differs from the A receptor both in agonist specificity (baclofen is a specific agonist) and its effects on cells. It modulates intracellular calcium levels through a Go mediated effect on N type calcium channels and also lowers intracellular cAMP levels by an effect on adenylyl cyclase, thereby reducing the secretion of catecholamines. (05 Jan 1998) |