| fractional dose | A definite fraction of a full dose; given repeatedly at short intervals so that the full dose is taken within a specified period, usually one day. Synonym: fractional dose. (05 Mar 2000) |
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| L+ dose | The limes tod dose of diphtheria toxin, i.e., the smallest amount of toxin that, when mixed with one unit of antitoxin and injected subcutaneously into a 250-g guinea pig, results in death of the animal within 96 hours (based on the average in a series); on theoretical grounds, one might expect that the difference between the L+ and L0 dose's would be identical to 1 MLD, but this is not so in actual practice; with various toxic filtrates, the difference may range from several to more than 100 MLD's, indicating that the toxin-antitoxin combination is not a firm chemical union that occurs in constant proportions. (05 Mar 2000) |
| lethal dose | <pharmacology> The amount, or dosage, of a toxin necessary to cause death. (16 Mar 1998) |
| lethal dose 50 | <pharmacology> The amount, or dosage, of a toxin necessary to kill 50% of the experimental subjects. (16 Mar 1998) |
| Lf dose | The limes flocculation dose of diphtheria toxin, i.e., the smallest amount of toxin that, when mixed with one unit of antitoxin, yields the most rapid flocculation in the Ramon test (in vitro); in general, the Lf dose is slightly less than the Lr dose. (05 Mar 2000) |
| loading dose | <pharmacology> A quantity higher than the average or maintenance dose, used at the initiation of therapy to rapidly establish a desired level of the drug (18 Nov 1997) |
| Lo dose | <pharmacology> The limes nul dose of diphtheria toxin, i.e., the largest amount of toxin that, when mixed with one unit of antitoxin and injected subcutaneously into a 250-g guinea pig, yields no recognizable reaction in the average of a series; actually, the Lod. Is usually recorded as the one that causes a barely perceptible local oedema at the site of inoculation. (05 Mar 2000) |
| Lr dose | The limes reacting dose of diphtheria toxin, i.e., the smallest amount of toxin that, when mixed with one unit of antitoxin and injected intracutaneously in the shaved skin of a susceptible guinea pig, yields a minimal, positive reaction and inflammation localised to the region of the injection; the Lrd. Closely approximates the Lod., as would be expected, inasmuch as a slight excess of unneutralised toxin results in a reaction. (05 Mar 2000) |
| 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) |