| nitric acid | <chemical> Nitric acid (hno3). A colourless liquid that is used in the manufacture of inorganic and organic nitrates and nitro compounds for fertilisers, dye intermediates, explosives, and many different organic chemicals. Continued exposure to vapor may cause chronic bronchitis; chemical pneumonitis may occur. Chemical name: Nitric acid (12 Dec 1998) |
|---|---|
| nitric acid reductase | <enzyme> Found in pseudomonas stutzerie; transforms nitric oxide to nitrous oxide in an ascorbate-phenazine methosulfate-dependent reaction; not EC 1.7.99.2 Registry number: EC 1.7.99.- (26 Jun 1999) |
| nitric | <chemistry> Of, pertaining to, or containing, nitrogen; specifically, designating any one of those compounds in which, as contrasted with nitrous compounds, the element has a higher valence; as, nitric oxide; nitric acid. Nitric acid, a colourless or yellowish liquid obtained by distilling a nitrate with sulphuric acid. It is powerfully corrosive, being a strong acid, and in decomposition a strong oxidizer. Nitric anhydride, a white crystalline oxide of nitrogen (N2O5), called nitric pentoxide, and regarded as the anhydride of nitric acid. Nitric oxide, a colourless poisous gas (NO) obtained by treating nitric acid with copper. On contact with the air or with oxygen, it becomes reddish brown from the formation of nitric dioxide or peroxide. Origin: Cf. F. Nitrique. See Niter. Source: Websters Dictionary (01 Mar 1998) |
|---|---|
| nitric oxide | <biochemistry> This compound is produced from L arginine by the enzyme nitric oxide synthase. Acts as a potent vasorelaxant via elevation of intracellular cGMP in vascular smooth muscle. Synthesis of nitric oxide is not confined to endothelium, isoforms of nitric oxide synthase are also found in brain, neutrophils and platelets. Synonym: endothelium derived relaxation factor. Acronym: NO (29 Dec 1997) |
| nitric-oxide reductase | <enzyme> Prior to 1992 was classified as EC 1.7.99.2; a cytochrome bc complex; genbank af002217 (norb protein) and af002661 (norz protein) are from alcaligenes eutrophus Registry number: EC 1.7.99.7 Synonym: nitric oxide reductase, norb gene product, norz gene product (26 Jun 1999) |
| nitric oxide synthase | <enzyme> An enzyme that catalyses the conversion of l-arginine, NADPH, and oxygen to citrulline, nitric oxide, and NADP+. The enzyme found in brain, but not that induced in lung or liver by endotoxin, requires calcium.There are two isoforms, one constitutive and one activated by calmodulin. Chemical name: L-Arginine,NADPH:oxygen oxidoreductase (nitric-oxide-forming) Registry number: EC 1.14.13.39 Acronym: NOS (12 Dec 1998) |
| 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) |
| acetrizoic acid | <chemical> A water-soluble, iodinated radiographic contrast medium, used as sodium acetrizoate in hysterosalpingography. Pharmacological action: contrast media. Chemical name: Benzoic acid, 3-(acetylamino)-2,4,6-triiodo- (12 Dec 1998) |
| acetylsalicylic acid | <drug> An odourless, white, slightly bitter drug used to reduce pain, fever, inflammation and sometimes to prevent blood clotting. Also called aspirin. Some people cannot tolerate it because it can cause stomach bleeding, however. It is soluble in both water and alcoholand melts at 132 to 136 degrees C. (06 May 1997) |
| acetyltannic acid | An astringent used for treatment of diarrhoea. Synonym: diacetyltannic acid, tannylacetate. (05 Mar 2000) |
| acid | <chemical, chemistry> A fundamental category of many compounds whose water-based solutions have a sour taste, turn blue litmus paper red and can combine with metals to form salts. They are chemical compounds which yield hydrogen ions or protons when dissolved in water, whose hydrogen can be replaced by metals or basic radicals, or which react with bases to form salts and water (neutralization). An extension of the term includes substances dissolved in media other than water. Specific types of acids include: Arrhenius acid: any chemical that increases the number of free hydrogen ions (H+) when added to a water-based solution. The more free hydrogens produced, the stronger the acid. Bronsted or Bronsted-Lowry acid: any chemical that acts as a proton donor in a chemical reaction. Lewis acid: any chemical that accepts two electrons to form a covalent bond during a chemical reaction. (13 Nov 1997) |