| Schardinger reaction | The reduction of methylene blue to methylene white by formaldehyde is rapidly catalyzed by fresh milk but not by boiled milk, the catalyzing agent being xanthine oxidase (Schardinger's enzyme); an example of oxidation in the absence of O2 with an organic hydrogen acceptor (the dye). (05 Mar 2000) |
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| Herxheimer's reaction | An inflammatory reaction in syphilitic tissues (skin, mucous membrane, nervous system, or viscera) induced in certain cases by specific treatment with Salvarsan, mercury, or antibiotics; believed to be due to a rapid release of treponemal antigen with an associated allergic reaction in the patient. Synonym: Jarisch-Herxheimer reaction. (05 Mar 2000) |
| Schultz-Charlton reaction | The specific blanching of a scarlatinal rash at the site of intracutaneous injection of scarlatina antiserum. Synonym: Schultz-Charlton phenomenon. (05 Mar 2000) |
| Schultz-Dale reaction | The contraction of an excised intestinal loop (Schultz) or of an excised strip of virginal uterus (Dale) from a sensitised animal (guinea pig) which occurs when the tissue is exposed to the specific antigen. (05 Mar 2000) |
| Schwartzmann reaction | Mis spelling of Shwartzman reaction. (18 Nov 1997) |
| prussian blue reaction | The reaction of potassium ferrocyanide with ferric iron to yield a dark blue precipitate at the sites of the ferric iron. Used to determine ferric iron in tissues, particularly in the diagnosis of disorders of iron metabolism. (12 Dec 1998) |
| xanthoprotein reaction | A qualitative test for proteins; a yellow product is formed by reacting proteins with hot, concentrated nitric acid. (05 Mar 2000) |
| Hill reaction | <plant biology> Reaction, first demonstrated by Robert Hill in 1939, in which illuminated chloroplasts evolve oxygen when incubated in the presence of an artificial electron acceptor (e.g. Ferricyanide). The reaction is a property of photosystem II. (11 Jan 1998) |
| psychogalvanic reaction | A change in electrical resistance of the skin, occurring in emotion and in certain other conditions. (12 Dec 1998) |
| homograft reaction | Rejection of an allogenic graft by the host. (05 Mar 2000) |
| host versus graft reaction | The normal lymphocyte mediated reactions of a host against allogeneic or xenogeneic cells acquired as a graft or otherwise, which lead to damage or/and destruction of the grafted cells. The opposite of graft-versus-host reaction. The common basis of graft rejection. (18 Nov 1997) |
| host vs graft reaction | The immune responses of a host to a graft. A specific response is graft rejection. (12 Dec 1998) |
| hunting reaction | An unusual reaction of digital blood vessels exposed to cold; vasoconstriction is alternated with vasodilation in irregular repeated sequences, in an apparent hunting of equilibrium of skin temperature. Synonym: hunting phenomenon. (05 Mar 2000) |
| serum reaction | A hypersensitivity response (type III) to the injection of large amounts of antigen, as might happen when large amounts of antiserum are given in a passive immunisation. The effects are caused by the presence of soluble immune complexes in the tissues. (18 Nov 1997) |
| shortening reaction | The adaptive shortening of the extensor muscles of the limb of a decerebrate animal when the limb is extended after it has been flexed. Compare: lengthening reaction. (05 Mar 2000) |