| Marchi's reaction | Failure of the myelin sheath of a nerve to blacken when submitted to the action of osmic acid. (05 Mar 2000) |
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| Gerhardt's reaction | In fresh urine a red colour develops upon addition of FeCl3; no colour develops if the urine has first been boiled; this test has low specificity and sensitivity. Synonym: Gerhardt's reaction. (05 Mar 2000) |
| Carr-Price reaction | The reaction of antimony trichloride with vitamin A to yield a brilliant blue colour; this reaction forms the basis of several quantitative techniques for the determination of vitamin A. (05 Mar 2000) |
| redox reaction | <chemistry> A reaction in which one or more electrons are transferred. (09 Jan 1998) |
| catalatic reaction | Decomposition of H2O2 to O2 and H2O, as in the action of catalase; analogous to peroxidase reaction. (05 Mar 2000) |
| catastrophic reaction | The disorganised behaviour that is the response to a severe shock or threatening situation with which the person cannot cope. (05 Mar 2000) |
| Mazzotti reaction | A test for onchocerciasis using an oral test dose of diethylcarbamazine (50 or 100 mg), resulting in the appearance of an acute rash in 2 to 24 hours from death of microfilariae in the skin. Synonym: Mazzotti reaction. (05 Mar 2000) |
| Paul's reaction | Pus is rubbed into a scarification on a rabbit's eye; if the pus is from a variolous or vaccinal pustule a condition of epitheliosis develops in from 36 to 48 hours; the sputum of a smallpox patient is said to cause the same reaction. Synonym: Paul's test. (05 Mar 2000) |
| cell-mediated reaction | Immunological reaction of the delayed type, involving chiefly T lymphocytes, important in host defense against infection, in autoimmune diseases, and in transplant rejection. See: skin test. (05 Mar 2000) |
| Voges-Proskauer reaction | A chemical reaction used in testing for the production of acetyl methyl carbinol by various bacteria; potassium hydroxide is added to a 24-hour culture in a suitable medium and thoroughly mixed; the treated culture is exposed to air and is observed at intervals of 2, 12, and 24 hours; a positive reaction consists of the development of an eosin-like pink colour, due to the production of acetylmethylcarbinol, which in the presence of alkali and oxygen is oxidised to diacetyl. (05 Mar 2000) |
| chain reaction | A reaction in which a product reacts and thus continues the reaction. (09 Oct 1997) |
| Chantemesse reaction | A conjunctival reaction, especially as applied to typhoid. (05 Mar 2000) |
| reversed Prausnitz-Kustner reaction | The appearance of an urticarial reaction at the site of injection when serum containing reaginic antibody is injected into the skin of a person in whom the allergen is already present. (05 Mar 2000) |
| performic acid reaction | Oxidative destruction of the ethylene double bond (-HC==CH-) which is converted to a Schiff-reactive double aldehyde; used to indicate the presence of unsaturated lipids, such as phospholipids and cerebrosides, as well as cystine-rich substances, such as keratin, in tissue sections. (05 Mar 2000) |
| reversible reaction | A chemical reaction that takes place in either direction i.e., from the forward or reverse direction; ionization is such a reaction, as are reaction's involving racemases, isomerases, mutases, transferases, etc. (05 Mar 2000) |