| mixed opioid agonist-antagonist | <pharmacology> A compound that has an affinity for two or more types of opioid receptors and blocks opioid effects on one receptor type while producing opioid effects on a second receptor type. (13 Nov 1997) |
|---|---|
| competitive antagonist | An antimetabolite. (05 Mar 2000) |
| muscarinic antagonist | Drugs which bind with muscarinic cholinergic receptors but do not activate them, thus preventing access to acetylcholine; examples include atropine, scopolamine, propantheline, and pirenzepine. (05 Mar 2000) |
| H2 antagonist | <pharmacology> A class of anti-ulcer medication which work through the inhibition of basal and nocturnal gastric acid secretion by competitive inhibition of the action of histamine at histamine H2 receptor sites on the parietal cells. Drugs of this type block gastric acid secretion and are therefore clinically useful in treating duodenal ulcers. Examples include cimetidine (Tagamet), famotidine (Pepcid), nizatidine (Axid) and ranitidine (Zantac). (27 Sep 1997) |
| insulin antagonist | Something that opposes or fights the action of insulin. Insulin lowers the level of glucose (sugar) in the blood, whereas glucagon raises it, therefore, glucagon is an antagonist of insulin. (09 Oct 1997) |
| oestrogen antagonist | <pharmacology> A drug or compound which inhibit or antagonise the action or biosynthesis of oestrogen. Tamoxifen also has agonist or stimulatory actions as well as blocking effects. There are also selective oestrogen-receptor modulators (SERMs). For example, raloxifene (trade name Evista) is classified as a SERM because it prevents bone loss (like oestrogen) and lowers serum cholesterol (like oestrogen) but (unlike oestrogen) does not stimulate the endometrial lining of the uterus. (12 May 2002) |
| enzyme antagonist | An antimetabolite or inhibitor of enzyme action. (05 Mar 2000) |
| folate antagonist | <pharmacology> One of a group of substances which blocks the formation of nucleotides that require the presence of folate (one of the B vitamins) before they can be made. The substance does this by blocking key steps in the reaction sequence. These substances are often used to treat cancer because fast-growing cancerous cells usually need to use the blocked reactions more than normal cells. (09 Oct 1997) |
| Rambourg's chromic acid-phosphotungstic acid stain | <technique> A stain for glycoproteins, used with an electron microscope, with which ultrathin tissue sections reveal complex carbohydrates in the same locations as shown by Rambourg's periodic acid-chromic methenamine-silver stain. (05 Mar 2000) |
| a1-acid glycoprotein | <biology> Plasma protein of mammals and birds, 38% carbohydrate. In humans a single chain glycoprotein of 39 kD. Increased levels are associated with inflammation, pregnancy and various diseases. (18 Nov 1997) |
| abscisic acid | <biochemistry> A lipid hormone that inhibits cell growth in plants, it is associated with fruit drop, leaf death and seed dormancy. It is synthesised in the plastids from carotenoids. This hormone helps plants deal with water loss, and its effects can be reversed with gibberellins. (06 May 1997) |
| abscisic acid 8'-hydroxylase | <enzyme> Catalyses conversion of abscisic acid to 8'-hydroxyabscisic acid, which rearranges to phaseic acid Registry number: EC 1.14.99.- Synonym: aba 8'-hydroxylase (26 Jun 1999) |
| acetic acid | <chemical> The acid most commonly associated with vinegar, it is the most commercially important organic acid and is used to manufacture a wide range of chemical products, such as plastics and Acetobacter but, except for making vinegar, is usually made through synthetic processes. Derivatives of acetic acid which may be formed by substitution reactions. Mono- and di-substituted, as well as, halogenated compounds have been synthesised. Experimentally, alpha- and n2- substituted acetic acids have been examined for their anti-inflammatory activity and effect on the central nervous system respectively. Additionally, limited exposure data has been collected on dibromo and dichloroacetic acids to determine whether they pose health effects. Synonym: ethanoic acid. (26 Jun 1999) |
| acetoacetic acid | CH3COCH2COOH;one of the ketone bodies, formed in excess and appearing in the urine in starvation or diabetes. Synonym: diacetic acid. (05 Mar 2000) |
| acetohydroxamic acid | C2H5NO2; N-Hydroxyacetamide;an inhibitor of urease, used as adjunctive therapy in chronic urea-splitting urinary infections. (05 Mar 2000) |