| lymphocyte function associated antigen | A member of the integrin family that is expressed on all leukocytes and binds to ICAM-1 and ICAM-2 on a variety of cells. (05 Mar 2000) |
|---|---|
| lymphocyte function-associated antigen-1 | A heterodimer molecule widely expressed on cells of haematopoietic origin. Cd11a antigen comprises the alpha chain and the CD18 antigen (antigens, CD18) the beta chain. Lfa-1 is a major receptor of T-cells, B-cells, and granulocytes. It mediates the leukocyte adhesion reactions underlying cytolytic conjugate formation, helper T-cell interactions, and antibody-dependent killing by natural killer cells and granulocytes. Intracellular adhesion molecule-1 (icam-1) has been defined as a ligand for lfa-1. (12 Dec 1998) |
| lymphogranuloma venereum antigen | A sterile preparation of inactivated chlamydiae grown in the yolk sac of domestic fowl and used as an antigen in the Frei test. (05 Mar 2000) |
| Lyt antigen | A set of plasmalemmal surface glycoproteins on mouse T lymphocytes. Possession of Lyt 1 partly defines a T helper cell and of Lyt 2, 3 suppressor and cytotoxic cells. Formerly known as Ly antigens. See: Lyb antigen. (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) |
| acid phosphatase test for semen | A screening test for semen by determining acid phosphatase content; because seminal fluid contains high concentrations of acid phosphatase, while other body fluids and extraneous foreign materials have very low concentrations, high values of acid phosphatase on vaginal aspirate or lavage, or on wash fluid from stains, render positive identification of semen, even if the male is aspermic. (05 Mar 2000) |
| acid reflux test | A test to detect gastroesophageal reflux by monitoring oesophageal pH by an electrode in the distal oesophagus either basally or after acid is instilled into the stomach. (05 Mar 2000) |
| ACTH stimulation test | A test for adrenal cortical function; ACTH administered by continuous intravenous infusion, or intramuscularly, evokes an increase in plasma cortisol in normal persons; in adrenal cortical insufficiency, the expected increase in plasma cortisol is limited or nonexistent. (05 Mar 2000) |
| ACTH suppression test | <investigation> A test that measures the response of the adrenal glands to ACTH. In this case, dexamethasone is given to the patient and then blood cortisol levels are measured. Under normal conditions, cortisol levels should drop in response to dexamethasone. In this test one milligram of dexamethasone is administered in the morning and then the blood is drawn for analysis the following morning. Abnormal test results can indicate Cushing's syndrome. (27 Sep 1997) |
| adhesion test | The diagnostic application of the immune adhesion phenomenon. Synonym: erythrocyte adherence test, immune adhesion test, red cell adherence test. (05 Mar 2000) |