(1) The proposed assay should be useful for in vitro metabolic studies of 1,2-dihaloethanes and mustards and has potential application for similar studies of monohalogenated ethanes, ethanols, and ethenes.
(2) A total of nine chlorinated ethanes and ethenes were circulated over lithium hydroxide in a laboratory scale closed system simulator.
(3) The level of adducts from ethene, determined as N-(2-hydroxyethyl)valine, was also higher in mice from diet S than in animals fed diet C, when all treatment groups were considered.
(4) About equimolar concentrations of bleomycin and FeCl3 resulted in optimal ethene formation.
(5) Halogenated ethenes are oxidatively metabolized by cytochrome P-450 to intermediates which inactivate cytochrome P-450 by destroying heme and to epoxides which may react with cellular macromolecules or decompose to other products.
(6) Previous mixed-culture studies have demonstrated that complete dechlorination to ethene is possible, although the final dechlorination step from vinyl chloride to ethene is rate limiting, with significant levels of vinyl chloride typically persisting.
(7) The results demonstrate a raised level of hydroxyethylation of N-terminal valine of Hb of smokers that is quantitatively compatible with ethene in the smoke being the source.
(8) Lipid peroxidation and metabolism of intestinal bacteria, giving rise to ethene, precursor of ethylene oxide, are thus indicated to be sources of observed background hydroxyethylations.
(9) The bioconversions with the three most promising ethene-utilizers (M26, M90C, M93A) were scaled-up to yield essentially optically pure (enantiomeric excess = 93%) S-(+)-phenyl glycidyl ether.
(10) This figure is compatible with a metabolic conversion of 3% (1-10%) of the inhaled ethene to ethylene oxide.
(11) KMBA was converted to ethene by dithranol under aerobic conditions, whereas ethene formation was negligible in the absence of oxygen.
(12) Ethene formation depended on oxygen, NADPH, FeCl3 and the enzyme.
(13) The limitations of Fluosol DA led to fluorocarbons under investigation such as F dimethyl bicyclononanes, F methyladamantane, bis (F-butyl) ethene or F-octylbromide.
(14) Eighteen newly isolated ethene- and propene-utilizing bacteria were screened for the ability to produce phenyl glycidyl ether, a common precursor for the synthesis of beta blockers, from phenyl allyl ether.
(15) O2- - and .OH-scavengers such as rutin, catechin, dimethyl sulfoxide, mannitol, ethanol, sodium salicylate and propyl gallate as well as catalase and superoxide dismutase inhibited ethene formation.
(16) Because the singlet oxygen (1O2) sensitizer, rose bengale, showed enlarged production of ethene when irradiated in the presence of KMBA, experiments were performed in the dark in order to avoid 1O2 production by dithranol.
(17) Efforts to measure adducts originating from ethene in environmental tobacco smoke and urban air show, however, that the resolving power of the methods used for identifying unknown risk factors must be increased.
(18) The detection limit was one pmol ethene or ethane per five mL air sample; the within-run precision (CV) of analysis was 2.1 percent at an ethane concentration of 16 pmol per five mL sample.
(19) For unknown reasons, uninduced mice varied strongly in the extent to which they converted ethene to epoxide.
(20) A sixth chlorinated ethene, tetrachloroethylene, was not degraded by the methane-utilizing culture under these conditions.
Methene
Definition:
(n.) See Methylene.
Example Sentences:
(1) Chemiluminescence appears to result from a side reaction involving singlet oxygen attack on the alpha-methene bridge, yielding a dioxetane.
(2) At high concentrations, they inhibited heme oxygenase [heme, hydrogen-donor:oxygen oxidoreductase (alpha-methene-oxidizing, hydroxylating), EC 1.14.99.3] in vitro.
(3) Selenium was found to be a novel regulator of cellular heme methabolism in that the element induced both the mitochondrial enzyme delta-aminolevulinate synthase [succinyl-CoA:glycine C-succinyltransferase (decarboxylating); EC 2-3-1-37] and the microsomal enzyme heme oxygenase [heme, hydrogen-donor:oxygen oxidoreductase(alpha-methene-oxidizing, hydroxylating); EC 1-14-99-3] in liver.
(4) Molecular-mechanics calculations with the three-dimensional structural co-ordinates of catalase shows that these proportions of products can be accounted for by the relative accessibility of the four methene bridges to a haem-linked oxygen molecule, thus further confirming Brown's [(1976) Biochem.
(5) Porphyrins with aromatic substitutions at the methene bridges (2a, 2b) did not inhibit the conversion of heme to bilirubin, even at relatively high concentrations.
(6) A model is proposed in which an oxygen molecule, bound to the haem iron atom, attacks a methene-bridge carbon atom in an intramolecular reaction.
(7) We investigated two compounds with substitutions at the 2 and 4 position of the porphyrin ring, iron deuteroporphyrin 2,4 disulfonic (1a) and iron deuteroporphyrin 2,4 bis glycol (1b), and two compounds with substitutions of aromatic groups on the methene bridges of the porphyrin molecule, meso-tetra-4-carboxyphenyl-porphine (2a) and meso-tetra-4-sulfonatophenyl-porphine (2b).
(8) Heme oxygenase (decyclizing) [heme,hydrogen-donor:oxygen oxidoreductase (alpha-methene-oxidizing, hydroxylating), EC 1.14.99.3] is greatly induced in the kidney by the administration of nickel or tin.
(9) Compounds derived from phosphoenolpyruvate by replacing the methene group by similarly hydrophobic groups such as hydrogen or the methyl group were permeant but those with the hydrophilic hydroxymethyl group were impermeant.
(10) 45% of the haem groups have been cleaved at the alpha-methene bridge, 55% at the beta-bridge and a trace at the delta-bridge.
(11) It is concluded that (a) the CO produced during lipid peroxidation originates from a source different from haem and (b) the degradations of haem caused by lipid peroxidation and 2-allyl-2-isopropylacetamide do not involve to any significant extent evolution of the methene-bridge carbon of haem as CO.
(12) Specificity of macrocyclic ring cleavage is explained on the basis of the different accessibilities of the bound oxygen molecule to the four methene bridges.
(13) A scheme for the oxidation of iron(III) oxyporphyrin to iron(II) verdoheme by O2 that proposes a mechanism for the expulsion of CO and the replacement of a methene bridge of the porphyrin ring by an oxa bridge is presented.