| nicotinic acid | A precursor of NAD, that is a product of the oxidation of nicotine. (18 Nov 1997) |
|---|---|
| nicotinic acid amide | <biochemistry> Member of the water soluble B vitamin group, used in the production of fatty acids, steroids and cholesterol, deficiency is known as pellagra. Has cholesterol-lowering and vasodilating properties. (27 Sep 1997) |
| nicotinic acid maculopathy | Maculopathy observed in persons taking 3000 mg or more of nicotinic acid daily; normal vision returns after this medication is discontinued. (05 Mar 2000) |
| nicotinic acids | 2-, 3-, or 4-pyridinecarboxylic acids. Pyridine derivatives substituted with a carboxy group at the 2-, 3-, or 4-position. The 3-carboxy derivative (niacin) is active as a vitamin. (12 Dec 1998) |
| receptors, nicotinic | One of the two major classes of cholinergic receptors. Nicotinic receptors were originally distinguished by their preference for nicotine over muscarine. They are generally divided into muscle-type and neuronal-type (previously ganglionic) based on pharmacology, molecular biology, and biophysical properties of the channels. (12 Dec 1998) |
|---|---|
| nicotinic | <chemistry> Pertaining to, or derived from, nicotine; nicotic; used specifically to designate an acid related to pyridine, obtained by the oxidation of nicotine, and called nicotinic acid. Source: Websters Dictionary (01 Mar 1998) |
| nicotinic acetylcholine receptor | Integral membrane protein of the postsynaptic membrane to which acetylcholine binds. The receptor contains an integral ion channel, as a result of binding of acetylcholine, ion channels in the subsynaptic membrane are opened. at the neuromuscular junction, the nicotinic acetylcholine receptor initiates muscle contraction. Currently the best characterised ion channel protein: made of a hetero pentamer of related subunits, although a homo pentamer is functional in insects. Structural studies show that the acetylcholine binding site and the ionic channel are part of the same macromolecular unit. The nAChR mediates rapid transduction events (1ms) whereas receptors activating G-protein coupled channels operate on slower time scales (millisecond to second range). (18 Nov 1997) |
| nicotinic agonists | Drugs that bind to and activate nicotinic cholinergic receptors (receptors, nicotinic). Nicotinic agonists act at postganglionic nicotinic receptors, at neuroeffector junctions in the peripheral nervous system, and at nicotinic receptors in the central nervous system. Agents that function as neuromuscular depolarising blocking agents are included here because they activate nicotinic receptors, although they are used clinically to block nicotinic transmission. (12 Dec 1998) |
| nicotinic alcohol | <chemical> 3-pyridinemethanol. A direct-acting peripheral vasodilator that causes flushing and may decrease blood pressure. It is used in vasospasm and threatened gangrene. Pharmacological action: vasodilator agents. Chemical name: 3-Pyridinemethanol (12 Dec 1998) |
| nicotinic antagonists | Drugs that bind to nicotinic cholinergic receptors (receptors, nicotinic) and block the actions of acetylcholine or cholinergic agonists. Nicotinic antagonists block synaptic transmission at autonomic ganglia, the skeletal neuromuscular junction, and at central nervous system nicotinic synapses. (12 Dec 1998) |
| nicotinic cholinergic receptor | A class of receptors responsive to acetylcholine that also are activated by nicotine; ganglionic (including the adrenal medulla) and neuromuscular receptors. Two classes exist: nicotinic-neuronal and nicotinic-muscular. (05 Mar 2000) |
| nicotinic receptors | A class of cholinergic receptors on skeletal muscle cells that are linked to ion channels in the cell membrane. (05 Mar 2000) |
| 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) |