| chromaffin reaction | Production of a yellow-brown to brown colouration in normal and abnormal cells containing epinephrine and norepinephrine, when fresh tissue slices are placed in a dichromate-chromate mixture overnight; useful for detection of pheochromocytoma (adrenal medulla) and other tumours which produce catecholamines. (05 Mar 2000) |
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| circular reaction | In sensorimotor theory, the tendency of an organism to repeat novel experiences. (05 Mar 2000) |
| phosphoroclastic reaction | Cleavage of C-C bonds that involves phosphate transfer but not, as in phosphorolysis, directly to one of the products; e.g., the decomposition of pyruvate to acetate + CO2, in which Pi is added to ADP to form ATP. (05 Mar 2000) |
| Millon reaction | The reaction of phenolic compounds (e.g., tyrosine in protein) with Hg(NO3)2 in HNO3 (and a trace of HNO2) to give a red colour. (05 Mar 2000) |
| photosynthetic reaction centre, bacterial | A system consisting of proteins and cofactors which acts as a light-driven electron pump across the photosynthetic membrane of photosynthetic bacteria. (12 Dec 1998) |
| photosynthetic reaction centre, plant | A system consisting of proteins and cofactors which facilitates light energy and electron transfer in plants. (12 Dec 1998) |
| miostagmin reaction | A physiochemical immunity test, designed by Ascoli, consisting in determination of the surface tension of an immune serum to which its specific antigen has been added, before and after incubation at 37캜 for 2 hours; in a positive reaction the surface tension, as measured by the stalagmometer, is lowered. (05 Mar 2000) |
| Mitsuda reaction | A delayed hypersensitivity lepromin reaction, in the form of erythematous papular nodules, at the site of intradermal injection of Mitsuda antigen in a lepromin test. (05 Mar 2000) |
| mixed agglutination reaction | Immune agglutination in which the aggregates contain cells of two different kinds but with common antigenic determinants; when used to identify isoantigens, the test cells are exposed to appropriate isoantibody, washed, and then mixed with indicator erythrocytes that combine with free sites on the test cell-attached isoantibody. Synonym: mixed agglutination. (05 Mar 2000) |
| mixed lymphocyte reaction | <haematology, immunology, investigation> Reaction of mitogenesis produced in T lymphocytes when allogeneic (i.e. Mixed) lymphocytes are brought together, provided they are mismatched in histocompatibility loci. Once used as a test for possible graft compatibility in human grafting. Now known that a negative reaction is a poor predictor of graft acceptance. (18 Nov 1997) |
| cockade reaction | A test of historical interest: tuberculin, either pure or diluted, is injected intracutaneously into a guinea pig; if the animal is tuberculous, a large papule with a necrotic haemorrhagic centre appears in about 24 hours (cocarde or cockade reaction). (05 Mar 2000) |
| Wassermann reaction | <investigation> A complement fixation test used to diagnose syphilis. (31 Dec 1997) |
| monocytic leukemoid reaction | Leukocytosis of varying degree, e.g., 30,000 to 40,000 per cu mm, with adult monocytes and immature forms amounting to 30% (or more) of the total number of white blood cells in the circulating blood; may be observed in association with tuberculosis, especially the first infection, miliary type. (05 Mar 2000) |
| monomolecular reaction | A reaction involving a single molecule (e.g., decomposition, intramolecular rearrangement, intramolecular oxidation or reduction), even if a catalytic agent, such as acid or alkali, is present in large excess, on a molecular basis, or is not rate-determining; such reaction's are usually first-order reaction's. Compare: molecularity. Synonym: unimolecular reaction. (05 Mar 2000) |
| colloidal gold reaction | A test (now obsolete) based on precipitation of cerebrospinal fluid protein when mixed with colloidal gold. Abnormalities in this reaction were observed in patients with syphilis, multiple sclerosis, poliomyelitis, and encephalitis. (05 Mar 2000) |