| 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) |
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| 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) |
| Shwartzman reaction | <investigation> Reaction that occurs when two injections of endotoxin are given to the same animal, particularly rabbits, 24h apart. In the local Shwartzman reaction the first injection is given intradermally, the second intravenously and a haemorrhagic reaction develops at the dermal site. If both injections are intravenous the result is a generalised Shwartzman reaction, often accompanied by disseminated intravascular coagulation. The reaction depends upon the response of platelets and neutrophils to endotoxin. (18 Nov 1997) |
| hypersensitivity reaction | <immunology> The bodys response to an allergic stimulus. This can be localised to one area or generalised and may include: rash, itching, hives, swelling, difficulty breathing, and/or low blood pressure. (27 Sep 1997) |