| histamine shock | The shock state produced in animals by the injection of histamine; characterised by bronchiolar spasm in the guinea pig and constriction of hepatic veins in the dog. (05 Mar 2000) |
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| histamine test | A test for maximal production of gastric acidity or anacidity; after preliminary administration of an antihistamine, histamine acid phosphate is injected subcutaneously in a dose of 0.04 mg/kg of body weight, followed by analysis of gastric contents. Synonym: augmented histamine test. (05 Mar 2000) |
| histamine-fast | Indicating the absence of the normal response to histamine, especially in speaking of true gastric anacidity. (05 Mar 2000) |
| histaminic cephalalgia | <symptom> A term used to describe a headache that is typified by constant, unilateral pain around the eye, with onset usually within 2-3 hours of falling asleep. Can be accompanied by a blocked nasal passage, runny nose, and-or tearing. One may also notice facial flushing, ptosis (dropping eyelid), facial swelling and constriction of the pupils. (27 Sep 1997) |
| histaminic headache | <symptom> A term used to describe a headache that is typified by constant, unilateral pain around the eye, with onset usually within 2-3 hours of falling asleep. Can be accompanied by a blocked nasal passage, runny nose, and-or tearing. One may also notice facial flushing, ptosis (dropping eyelid), facial swelling and constriction of the pupils. (27 Sep 1997) |
| histaminuria | The excretion of histamine in the urine. Origin: histidine + G. Ouron, urine (05 Mar 2000) |
| histangic | Relating to the structure of blood vessels, especially in terms of their function. Synonym: histangic. Origin: histo-+ G. Angeion, vessel (05 Mar 2000) |
| histic epipedon | An 8- to 16-inch soil layer at or near the surface that is saturated for 30 consecutive days or more during the growing season in most years and contains a minimum of 20 percent organic matter when no clay is present or a minimum of 30 percent organic matter when 60 percent or more clay is present, generally a thin horizon of peat or muck if the soil has not been plowed. (09 Oct 1997) |
| histidase | <enzyme> An enzyme of the lyase class that catalyses the reaction of l-histidine to form urocanate and ammonia. The reaction is the initial step of histidine catabolism. Genetic deficiency of the enzyme, transmitted as an autosomal recessive trait, causes histidinaemia. Chemical name: L-Histidine ammonia-lyase Registry number: EC 4.3.1.3 (12 Dec 1998) |
| histidinaemia | <biochemistry> A medical condition in which the amount of the amino acid histidine in the blood is abnormally high.Also, histidine is present in the urine and the amount of the enzyme histidase (which breaks down histidine) is abnormally low. Mild retardation and speech or reading disorders often occur along with histidinaemia. (11 Jan 1998) |
| histidinal | The aldehyde analogue of histidine (-CHO replacing -COOH). (05 Mar 2000) |
| histidinase | <enzyme> An enzyme of the lyase class that catalyses the reaction of l-histidine to form urocanate and ammonia. The reaction is the initial step of histidine catabolism. Genetic deficiency of the enzyme, transmitted as an autosomal recessive trait, causes histidinaemia. Chemical name: L-Histidine ammonia-lyase Registry number: EC 4.3.1.3 (12 Dec 1998) |
| histidine | <amino acid> An amino acid with an imidazole side chain with a pKa of 6-7. Acts as a proton donor or acceptor and has high potential reactivity and diversity of chemical function. Forms part of the catalytic site of many enzymes. (18 Nov 1997) |
| histidine ammonia-lyase | <enzyme> An enzyme of the lyase class that catalyses the reaction of l-histidine to form urocanate and ammonia. The reaction is the initial step of histidine catabolism. Genetic deficiency of the enzyme, transmitted as an autosomal recessive trait, causes histidinaemia. Chemical name: L-Histidine ammonia-lyase Registry number: EC 4.3.1.3 (12 Dec 1998) |
| histidine deaminase | <enzyme> An enzyme of the lyase class that catalyses the reaction of l-histidine to form urocanate and ammonia. The reaction is the initial step of histidine catabolism. Genetic deficiency of the enzyme, transmitted as an autosomal recessive trait, causes histidinaemia. Chemical name: L-Histidine ammonia-lyase Registry number: EC 4.3.1.3 (12 Dec 1998) |