(n.) Any one of a series of nitrogenous bases, resembling the amines and produced by the reduction of certain nitroso and diazo compounds; as, methyl hydrazine, phenyl hydrazine, etc. They are derivatives of hydrazine proper, H2N.NH2, which is a doubled amido group, recently (1887) isolated as a stable, colorless gas, with a peculiar, irritating odor. As a base it forms distinct salts. Called also diamide, amidogen, (or more properly diamidogen), etc.
Example Sentences:
(1) The first comprises N1-[4-(4-alkyloxybenzamido)benzoyl]-N2-substituted alkylidene hydrazine, the second involves 1-[4-(4-alkyloxybenzamido)benzoyl]-4-alkyl, aryl, or aralkyl-3-thiosemicarbazides, and the third includes 1-substituted-5-[4-(4-alkyloxybenzamido)phenyl]-1,3,4-triazole-2-t hione.
(2) High resolution proton NMR spectroscopic analysis of urine also revealed resonances from several metabolites of hydrazine, an N-acetylcysteine conjugate of allyl alcohol, and acetamide as a metabolite of thioacetamide after dosing with the respective compounds.
(3) When hydrazine was used as the electron donor, no substrate inhibition was observed, suggesting that the inhibition resulted from reductant limitation.
(4) The hydrazine moiety liberated from isoniazid is primarily acetylhydrazine, and studies in animals show this metabolite to be converted to a potent acylating agent that produces liver necrosis.
(5) The weekly administration of 1,2-dimethyl-hydrazine (DMH) by subcutaneous injection for a period of 16-20 weeks is a well known procedure for producing colonic tumors in mice and rats.
(6) The compounds were obtained by condensation of appropriate hydrazines with thiophene 2-carboxaldehyde (series 1), thiophene 3-carboxaldehyde (series 2), and 5-nitrothiophene-2-carboxaldehyde (series 3).
(7) After inhibition of monoamine synthesis by N'-(DL-SERYL)-N2-(2, 3, 4-trihydroxybenzyl)hydrazine, substance P significantly accelerated the disappearance of dopamine, noradrenaline and 5-hydroxytryptamine.
(8) Embryotoxicity has been demonstrated at very high exposures but not at occupationally encountered levels for hydrazine and unsymmetrical dimethylhydrazine.
(9) The characterization of the various disaccharides by Smith periodic acid degradation and glycosidase digestions was facilitated by the preparation and thin-layer chromatographic resolution of the complete series of monosulfated derivatives of anhydromannitol and anhydrotalitol; the sulfate esters were shown to be stable to both the hydrazine and nitrous acid treatments.
(10) This inactivation was very rapid but reversible, with regeneration of enzyme activity being spontaneous and hydrazine-accelerated, suggestive of the intermediacy of a stable acyl enzyme.
(11) Urinary excretion (0-24 h) of hydrazine and its metabolite acetylhydrazine were determined employing nitrogen-phosphorus detection of the adducts utilising a novel internal standard, pentafluorophenylhydrazine, the adduct of which structurally resembles DFBA.
(12) Modification of uridines with hydrazine has no effect on interaction with the enzyme, except for one uridine near the 3'-end of tRNA(Gly).
(13) With a specific gas chromatographic assay procedure, the amount of hydrazine in the 0- to 24-hr urine was determined in patients treated with various doses of hydralazine.
(14) A chromophoric hydrazide, 4'-N,N-dimethylamino-4-azobenzene sulfonyl hydrazide (DABS-hydrazide), was prepared from 4'-N,N-dimethylamino-4-azobenzene sulfonyl chloride by reaction with hydrazine.
(15) A GC procedure for the simultaneous determination of hydrazine and benzylhydrazine in isocarboxazid raw material and tablet formulations has been developed.
(16) Hydrazine sulfate compared with placebo addition to chemotherapy resulted in significantly greater caloric intake and albumin maintenance (P less than .05).
(17) The synthesis was achieved by reacting 3-benzylthiazolidin-2-one-4-thione with its 4-hydrazone derivative to give N,N'-bis(3-benzyl-2-oxo-4-thiazolidinylidene)hydrazine, which was subjected to dibromination followed by reaction with various primary aromatic amines.
(18) This study has demonstrated that the nasal respiratory epithelia of rats and hamsters are the most sensitive tissues to the tumorigenic action of hydrazine following inhalation exposures.
(19) In the study in mice described below, which was carried out according to modern guidelines, no carcinogenic action was detected for hydrazine even after the administration of toxic doses over the entire lifespan of the animals.
(20) It is concluded that hydrazine acts to produce and altered base, possibly N(4)-aminocytosine, that produces mutations by mispairing at replication rather than by error-prone repair.
Hydride
Definition:
(n.) A compound of the binary type, in which hydrogen is united with some other element.
Example Sentences:
(1) The corresponding hydrides, mono-n-butyltin hydride, di-n-butyltin hydride, tri-n-butyltin hydride, monophenyltin hydride, diphenyltin hydride triphenyltin hydride, are detected by electron-capture gas chromatography after clean-up by silica gel column chromatography.
(2) The latter compounds were reduced with lithium aluminium hydride to the respective amines (II a-c) and then N-alkylated by reaction with 2-propynyl-, 2-butynyl- or 2,3-butadienyl bromides to the corresponding amines (III a-j).
(3) The mechanism of hydrogen activation was shown to be heterolytic cleavage to an enzyme hydride and a proton.
(4) The lithium aluminum hydride reduction product of the 24R-acid (Vb) was identical with the naturally occurring 5 beta-ranol, hence 5 beta-ranol has the 24R configuration.
(5) An evaluation of the possible role of flavins (as a hydride carrier between NADPH and the steroid) has shown that progesterone 5 alpha-reduction is inhibited by high levels of flavins and flavin analogs.
(6) The higher the rate of hydride transfer at pH 7.65, the higher the pH of the cross-over point.
(7) Because we have been unable to detect trans coordination of 2-mercaptoethanol, we favor a mechanism that involves a hydride attack on the Co-methylene carbon of (carboxymethyl)cobalamin rather than a trans attack of the thiol on the cobalt atom.
(8) Only O-benzoylation occurred on reaction with benzoic an hydride.
(9) 40- and 60-S ribosomal subunits and 80-S ribosomes from rat liver were highly labelled by reductive methylation using formaldehyde and sodium boro-[3H] hydride, under conditions which did not decrease their activity in poly-U-directed polyphenylalanine synthesis.
(10) A new rapid high yield synthesis of radiolabeled N'-(4-11C-methyl)imipramine has been developed using a reductive-carboxylation approach, in which 11CO2 is reacted with either N'-trimethylsilyldesimipramine or N'-lithium derivative of desimipramine, followed by lithium aluminum hydride reduction, to give no carrier added or carrier added 11C-labeled imipramine respectively.
(11) Reduction of this mixture 1 with sodium aluminum bis-(methoxyethoxy)hydride furnished the 11 beta, 18, 21-triol 2a.
(12) The two mechanisms have been assessed in terms of the calculated absolute and relative pKas of the protonated species taking into account experimental information regarding possible stabilization of these forms in the enzyme active site and also the effectiveness of the various protonations in assisting the hydride ion transfer step.
(13) A radioactive label was introduced by using sodium boro[3H]hydride to reduce the initially formed Schiff's base.
(14) After deoxygenation of 2'-O-[[(4-methylphenyl)oxy]thiocarbonyl] compounds 20A-E with tributyltin hydride the 2,3'-anhydro bridge of the 2'-deoxynucleosides 21A-E was opened with LiN3 to produce the protected 3'-azido-2,3'-dideoxynucleoside derivatives 22A-G. Saponification with NaOCH3 gave 1-(3'-azido-2',3',5'-trideoxy-beta-D-allofuranosyl)thymine (2; homo-AZT), the 5'-C-(hydroxymethyl) derivatives of AZT 1-(3'-azido-2',3'- dideoxy-beta-D-allofuranosyl)thymine (3) and 1-(3'-azido-2',3'-dideoxy-alpha-L-talofuranosyl)thymine (4), and the 5'-C-methyl derivatives of AZT 1-(3'-azido-2',3',6'-trideoxy-beta-D-allofuranosyl)thymine (5) and 1-(3'-azido-2',3',6'-trideoxy-alpha-L-talofuranosyl)thymine (6).
(15) While further improvements might lead to potential enhancement of sensitivity and precision of as much as an order of magnitude, the present performance of the hydride system was satisfactory in relation to the requirements of isotopic analysis for metabolic investigations employing 74Se as the in vivo stable isotope tracer.
(16) These models, in turn, have suggested detailed mechanisms for the various chemical steps of the reaction: a ring opening catalysed by an activated histidine, a hydride-shift isomerization, and a ring closure which may be facilitated by a polarised water molecule.
(17) The disulfide form but not the sulfhydryl form of a boron hydride compound was found to be cataractogenic.
(18) Proper molecular orientation is required for hydride transfer (Dalziel and Dickinson, 1967).
(19) An alkylation technique using methyl iodide and sodium hydride in dimethyl sulfoxide has been evaluated for 3 carbamate and 7 urea herbicides in 9 foods.
(20) To determine the effectiveness of the selenium reduction and the completeness of the selenium hydride formation a parallel selenium determination was carried out by means of ICP-AES and FI-HAAS analysis.