| 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) |
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| 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) |
| Abbe test plate | <equipment> A long, wedge-shaped coverslip about 0.20 mm thick at one end and 0.10 to 0.12 mm at the other end coated chemically with a silver film on which are ruled horizontal lines. at each variation in thickness of 0.01 mm there are vertical lines. By means of oblique illumination and by focusing on different portions of the plate, it is possible to determine the optimum coverslip thickness for any objective and also, for microscopes with drawtubes, the tube length for best objective performance. The approximate freedom from spherical and chromatic aberrations can also be estimated. Small isolated bits of silver near the edges of the lines form good objects for the star test (05 Aug 1998) |
| acetone test | A test for ketonuria; the suspected urine is shaken up with a few drops of sodium nitroprusside, and strong ammonia water is then gently poured over the mixture; if acetone is present, a magenta ring forms at the line of contact; tablets containing sodium nitroprusside and alkali are now more commonly used. (05 Mar 2000) |
| achievement test | A standardised test used to measure acquired learning, e.g., competence in a specific subject area such as reading or arithmetic, in contrast to an intelligence test which is a useful index of potential ability or learning. (05 Mar 2000) |
| acidified serum test | Lysis of the patient's red cells in acidified fresh serum, specific for paroxysmal nocturnal haemoglobinuria. Synonym: Ham's test. (05 Mar 2000) |
| acid loading test | <nephrology> This is a test used in the diagnosis of renal tubular acidosis. The patient takes ammonium chloride capsules for 3 days to acidify the blood (lower blood pH). A sample of the urine and the blood is then collected and the results are interpreted. (27 Sep 1997) |
| acid perfusion test | <gastroenterology, investigation> A test used to diagnosis gastrooesophageal reflux disease. This investigation requires that the patient swallow 3 tiny tubes into the stomach. A mixture of hydrochloric acid (like stomach acid) and saline are alternatively injected into the tubes. The patient then reports any symptoms they may have. Some patients may vomit. (13 Nov 1997) |