| 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) |
| skin reaction | A method for determining induced sensitivity (allergy) by applying an antigen (allergen) to, or inoculating it into, the skin; induced sensitivity (allergy) to the specific antigen is indicated by an inflammatory reaction of one of two general kinds: 1) immediate, appears in minutes to an hour or so and in general is dependent upon circulating immunoglobulins (antibodies); 2) delayed, appears in 12 to 48 hours and is not dependent upon these soluble substances but upon cellular response and infiltration. Synonym: cutaneous test, cutireaction test, skin reaction. (05 Mar 2000) |
| specific reaction | The phenomena produced by an agent that is identical with or immunologically related to the one that has already caused an alteration in capacity of the tissue to react. (05 Mar 2000) |
| Nadi reaction | Formation of indophenol blue by the action of an oxidizing enzyme present in certain cells and tissues when they are treated with a solution of alpha-naphthol and dimethylparaphenylenediamine; by this method, cells of the myelocyte series, which give a positive reaction, may be distinguished from those of the lymphocyte series, which give a negative reaction; endothelial leukocytes give a variable reaction, probably positive when they have phagocytised the debris of myeloid cells. Synonym: Nadi reaction. (05 Mar 2000) |
| near reaction | The pupillary constriction associated with a near vision effort, i.e., with accommodation and convergence. (05 Mar 2000) |