| nicergoline | <chemical> An ergot derivative that has been used as a cerebral vasodilator and in peripheral vascular disease. It has been suggested to ameliorate cognitive deficits in cerebrovascular disease. Pharmacological action: adrenergic alpha-antagonists, nootropic agents, vasodilator agents. Chemical name: Ergoline-8-methanol, 10-methoxy-1,6-dimethyl-, 5-bromo-3-pyridinecarboxylate (ester), (8beta)- (12 Dec 1998) |
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| niceritrol | <chemical> 3-pyridinecarboxylic acid 2,2-bis((3-pyridinecarbonyl)oxy)methyl)-1,3-propanediyl ester. An ester of nicotinic acid that lowers cholesterol and triglycerides in total plasma and in the vld- and ld-lipoprotein fractions. Pharmacological action: antilipaemic agents. Chemical name: 3-Pyridinecarboxylic acid, 2,2-bis(((3-pyridinylcarbonyl)oxy)methyl)-1,3-propanediyl ester (12 Dec 1998) |
| niche | A cavity, hollow, or recess, generally within the thickness of a wall, for a statue, bust, or other erect ornament. Hence, any similar position, literal or figurative. "Images defended from the injuries of the weather by niches of stone wherein they are placed." (Evelun) Origin: F, fr. It. Nicchia, prop, a shell-like recess in a wall, fr. Nicchio a shellfish, mussel, fr. L. Mytilus. Source: Websters Dictionary (01 Mar 1998) |
| nick | <molecular biology> A point in a double stranded DNA molecule where there is no phosphodiester bond between adjacent nucleotides of one strand typically through damage or enzyme action. (18 Nov 1997) |
| nick translation | <molecular biology, technique> A technique used to radioactively label DNA. E. Coli DNA polymerase I will add a nucleotide, copying the complementary strand, to the free 3' OH group at a nick, at the same time its exonuclease activity removes the 5' terminus. The enzyme then adds a nucleotide at the new 3' OH and removes the new 5' terminus. In this way one strand of the DNA is replaced starting at a nick, which effectively moves along the strand. Nick translation refers to this translation or movement and not to protein synthesis. In practice, DNA is mixed with trace amounts of DNAase I to generate nicks, DNA polymerase I and labelled nucleotides. Because the nicks are generated randomly the DNA preparation can be uniformly labelled and to a high degree of specific activity. (10 Jan 1998) |
| Nick's procedure | Enlarges the aortic annulus by incising the noncoronary sinus and the roof of the left atrium. (05 Mar 2000) |
| nickar nut | <botany> Same as Nicker nut, Nicker tree. Source: Websters Dictionary (01 Mar 1998) |
| nickar tree | <botany> Same as Nicker nut, Nicker tree. Source: Websters Dictionary (01 Mar 1998) |
| nicked circle | <molecular biology> During extraction of plasmid DNA from the bacterial cell, onestrand of the DNA becomes nicked. This relaxes the torsional strain needed to maintain supercoiling, producing the familiar form of plasmid. (09 Oct 1997) |
| nickel | 1. <chemistry> A bright silver-white metallic element. It is of the iron group, and is hard, malleable, and ductile. It occurs combined with sulphur in millerite, with arsenic in the mineral niccolite, and with arsenic and sulphur in nickel glance. Symbol Ni. Atomic weight 58.6. On account of its permanence in air and inertness to oxidation, it is used in the smaller coins, for plating iron, brass, etc, for chemical apparatus, and in certain alloys, as german silver. It is magnetic, and is very frequently accompanied by cobalt, both being found in meteoric iron. 2. A small coin made of or containing nickel; especially, a five-cent piece. Nickel silver, an alloy of nickel, copper, and zinc; usually called german silver. Synonym: argentan. Origin: G, fr. Sw. Nickel, abbrev. From Sw. Kopparnickel copper-nickel, a name given in derision, as it was thought to be a base ore of copper. The origin of the second part of the word is uncertain. Cf. Kupfer-nickel, Copper-nickel. Source: Websters Dictionary (01 Mar 1998) |
| nickel dermatitis | Allergic dermatitis due to contact with, or in some cases ingestion of, nickel or other metals containing nickel (e.g., stainless steel) as a diluent. (05 Mar 2000) |
| nickel titanium | <dentistry> An especially strong orthodontic wire which allows for rapid tooth movement. (08 Jan 1998) |
| nickel-iron hydrogenase | <enzyme> From desulfovibrio multispirans Registry number: EC 1.12.- Synonym: nife hydrogenase, co-induced hydrogenase, co-tolerant hydrogenase (26 Jun 1999) |
| nickel-iron-selenium hydrogenase | <enzyme> From desulfovibrio baculatus Registry number: EC 1.12.- Synonym: nifese hydrogenase (26 Jun 1999) |
| nickelic | <chemistry> Pertaining to, or containing, nickel; specifically, designating compounds in which, as contrasted with the nickelous compounds, the metal has a higher valence; as nickelic oxide. Source: Websters Dictionary (01 Mar 1998) |