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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ethanol is known to acutely inhibit glucose-stimulated glycogen deposition in skeletal muscles in the rat. This effect is selective for oxidative as opposed to non-oxidative muscles. This paper explores the biochemical basis for this selective impairment in muscle glycogen metabolism. 4-Methylpyrazole, a potent inhibitor of alcohol dehydrogenase, potentiated the ethanol-mediated impairment in glycogen deposition in oxidative muscles and was associated with abnormalities in glycogen deposition in non-oxidative muscles. By contrast, disulfiram, a potent inhibitor of aldehyde dehydrogenase had no effect on the ethanol-mediated impairment in glycogen deposition in both oxidative and non-oxidative muscles. The implication is that it is the ethanol molecule itself, and not one of its metabolites (acetaldehyde, acetate, excess NADH), that mediates the defect in glycogen metabolism.
Biochem Mol Biol Int 1993 May
PMID:The mechanism(s) of the alcohol-induced impairment in glycogen synthesis in oxidative skeletal muscles. 835 29

The effects of chronic embryonic ethanol exposure were evaluated in chick ventricular muscle. Ethanol treatments were administered on embryonic days 11, 13, 15, and 17 and chicks were sacrificed at various time points following treatments. Fluctuations in embryonic blood ethanol levels were examined following treatments. Developmental increases in the activities of mitochondrial enzymes, cytochrome oxidase (CO) and citrate synthase (CS), were observed. Ethanol exposure resulted in a depression in CO activity, but not CS activity. Since, a maximal depression in CO activity was seen with ethanol treatments of 75 mg/100 g, this dosing paradigm was adopted for subsequent experiments. A tissue-specific effect of ethanol was demonstrated as CO activity was unchanged in atrial, liver, pectoralis, and brain tissues. The role of mitochondrial DNA replication and transcription during the developmental up-regulation and ethanol-induced down-regulation of CO activity was evaluated using a cDNA probe for cytochrome oxidase subunit III (COIII). The relative levels of COIII mRNA and mitochondrial DNA (cpm/mg protein) decreased by 3-fold and 4-fold, respectively, across the developmental time course, while CO activity increased by 3.5-fold. Therefore, increases in mitochondrial DNA and mitochondrial mRNA transcripts are unlikely to be responsible for the developmentally-regulated increases in CO activity. Similarly, embryonic ethanol exposure failed to elicit alterations in COIII mRNA levels, indicating that the ethanol-induced depression in CO activity was not transcriptionally regulated. However, ventricular mitochondrial DNA concentrations were elevated in ethanol-treated embryos, indicating that ethanol-exposure either directly or indirectly induces mitochondrial DNA replication.
J Mol Cell Cardiol 1993 Feb
PMID:Ventricular mitochondrial gene expression during development and following embryonic ethanol exposure. 838 53

Single blastomeres from eight-cell stage bovine embryos matured and fertilized in vitro were electrically fused with enucleated oocytes matured in vitro. In experiment 1, The percentage of these reconstituted embryos developed to the two- to eight-cell stage 48 hr after electrofusion was increased when both the eight-cell embryos and the enucleated oocytes were derived from oocytes cultured with granulosa cells (14% vs. 38%). In experiment 2, the relationship between activation of oocytes and developmental ability of reconstituted embryos was examined. Although both ethanol and electrical stimulation efficiently induced parthenogenetic activation of oocytes matured in vitro for 26-28 hr (ethanol, 89%; electrical stimulation, 73%), the ratio of the second polar body extrusion differed (80% vs. 22%). Ethanol-treated enucleated oocytes, however, were not significantly different from the early cleavage of the reconstituted embryos 48 hr after electrofusion (nontreated, 38%; treated, 43%). In experiment 3, reconstituted embryos at the two- to eight-cell stage 48 hr after the electrofusion were cocultured with granulosa cells for 6-7 days. Of 69 embryos, one developed to a morula and three developed to blastocysts.
Mol Reprod Dev 1993 Mar
PMID:Developmental ability of enucleated bovine oocytes matured in vitro after fusion with single blastomeres of eight-cell embryos matured and fertilized in vitro. 847 Dec 54

Large conductance, Ca(2+)-activated K+ channels are believed to underlie interburst intervals and, thus, contribute to the control of hormone release from neurohypophysial terminals. Because ethanol inhibits the release of vasopressin and oxytocin, we studied its effects on large conductance, Ca(2+)-activated K+ channels from these terminals using patch-clamp techniques. Ethanol (10-100 mM) applied to the cytosolic surface of excised, inside-out patches reversibly increases channel activity in a concentration-dependent manner, reaching a plateau at 50-100 mM. This activation is not mediated by freely diffusible cytosolic second messengers or the release of Ca2+ from intracellular stores. Rather, it likely reflects a direct interaction of ethanol with the channel protein or a closely associated component. Neither the unitary conductance nor the characteristics of the voltage-current relationship are modified by the drug. The increase of channel activity by ethanol results from a modification of channel gating properties: the contribution of long openings to the total time spent in the open state is increased, the average duration of the fast openings is slightly increased, and long closures disappear in the presence of the drug. The activation of large conductance, Ca(2+)-activated K+ channels by ethanol, in conjunction with the previously reported inhibition of voltage-dependent Ca2+ channels, can explain the reduced release of vasopressin and oxytocin after ethanol ingestion.
Mol Pharmacol 1996 Jan
PMID:Ethanol increases the activity of large conductance, Ca(2+)-activated K+ channels in isolated neurohypophysial terminals. 856 10

Because the carbamate insecticide propoxur induced sister chromatid exchanges (SCE) in Vicia faba but was ineffective in producing SCE in lymphocytes in culture, it was hardly suspected that plant metabolism was involved. Experiments were conducted in which metabolic activation was afforded by Vicia faba roots, and SCE in human lymphocytes in vitro was used to assess cytogenetic damage. Several concentrations of propoxur (250, 500, 1,000, 1,500, and 2,000 ppm) were applied for 4 hr to the roots of Vicia faba. Extracts prepared from these treatments were added to the lymphocyte cultures and a significant increase of SCE frequencies with a concentration-response relationship could be detected. The lymphocyte proliferation kinetics and the proliferation rate index (PRI) were not affected (except in the highest concentration, of 2,000 ppm). This general behavior was in agreement with the presence of an enzymatic system (S10 fraction) in Vicia roots capable of metabolizing or activating the propoxur. With 2,000 ppm, cell necrosis was produced in Vicia; therefore, this extract did not induce SCE in lymphocytes. However, lymphocyte proliferation kinetics were delayed and PRI was significantly decreased. Ethanol, a promutagen activated by this plant, was applied directly to the lymphocyte cultures as a positive control, and the response was negative. On the other hand, the extracts of roots treated with ethanol increased the SCE to more than twice that of the negative control, but the lymphocyte proliferation kinetics and PRI were not affected.
Environ Mol Mutagen 1995
PMID:Sister chromatid exchange in human lymphocytes induced by propoxur following plant activation by Vicia faba. 857 21

Uracil DNA N-glycosylase is a repair enzyme that releases uracil from DNA. A major function of this enzyme is presumably to protect the genome from pre-mutagenic uracil resulting from deamination of cytosine in DNA. Here, we report that human uracil DNA N-glycosylase also recognizes three uracil derivatives that are generated as major products of cytosine in DNA by hydroxyl radical attack or other oxidative processes. DNA substrates were prepared by gamma-irradiation of DNA in aerated aqueous solution and incubated with human uracil DNA N-glycosylase, heat-inactivated enzyme or buffer. Ethanol-precipitated DNA and supernatant fractions were then separated. Supernatant fractions after derivatization, and pellets after hydrolysis and derivatization were analyzed by gas chromatography/isotope-dilution mass spectrometry. The results demonstrated that human uracil DNA N-glycosylase excised isodialuric acid, 5-hydroxyuracil and alloxan from DNA with apparent K(m) values of approximately 530, 450 and 660 nM, respectively. The excision of these uracil analogues is consistent with the recently described mechanism for recognition of uracil by human uracil DNA N-glycosylase [Mol,C.D., Arval,A.S., Slupphaug,G., Kavil,B., Alseth,I., Krokan,H.E. and Tainer,J.A. (1995) Cell, 80, 869-878]. Nine other pyrimidine- and purine-derived products that were identified in DNA samples were not substrates for the enzyme. The results indicate that human uracil DNA N-glycosylase may have a function in the repair of oxidative DNA damage.
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PMID:Novel activities of human uracil DNA N-glycosylase for cytosine-derived products of oxidative DNA damage. 860 52

Ethanol can be oxidized to the 1-hydroxyethyl radical (HER) by rat and deer mice liver microsomal systems. Experiments were carried out to evaluate the ability of human liver microsomes to catalyze this reaction, compare the effectiveness of NADH with that of NADPH, and assess the possible role of cytochrome b5 in HER formation. HER was detected as the alpha-(4-pyridly-1 -oxide)-N-t-butylnitrone/HER adduct. Human liver microsomes catalyzed HER formation with either NADPH or NADH as cofactor; rates with NADH were approximately 50% those found with NADPH. Chelex-100 treatment of the reaction mixture produced marked inhibition of HER formation, suggesting that a transition metal, such as iron, was required to catalyze the reaction. The addition of ferric chloride restore HER formation. Catalase (2600 units/ml) and superoxide dismutases (500 units/ml) nearly completely inhibited the reaction with either NADPH or NADH. The NADH-dependent rates of superoxide production, detected as 5,5-dimethyl-1-pyrroline-N-oxide-O2H, were approximately 50% the NADPH-dependent rates, which is consistent with the rates of HER formation. Anti-cytochrome b5 IgG decreased NADPH- and NADH-dependent HER formation, and this was associated with inhibition of superoxide formation with both reductants. These results indicate that human liver microsomes can catalyze the oxidation of ethanol of HER with either NADPH or NADH as reductant. The effectiveness of NADH may be significant in view of the increased NADH/NAD+ redox ratio in the liver as a consequence of ethanol oxidation by alcohol dehydrogenase. HER formation by human liver microsomes seems to be catalyzed by an oxidant derived from the interaction of iron with superoxide or H2O2, and a close association exists between HER formation and superoxide production. Cytochrome b5 seems to play a role in HER formation, most likely due to its effect on superoxide production.
Mol Pharmacol 1996 May
PMID:1-Hydroxyethyl radical formation during NADPH- and NADH-dependent oxidation of ethanol by human liver microsomes. 862 31

Effects of ethanol on strychnine-sensitive glycine receptors were studied in Xenopus laevis oocytes expressing alpha 1 wild-type, alpha 2, or mutant alpha 1(A52S) homomeric glycine receptors. This alpha 1(A52S) mutant, in which a serine residue substitutes for alanine at amino acid 52, is responsible for the spasmodic phenotype in mice and alters the ability of glycine to activate the receptor. Pharmacologically relevant concentrations of ethanol (10-200 mM) reversibly potentiated the glycine receptor function in all receptors. Ethanol potentiation depended on the glycine concentration used, with decreased potentiation observed at higher glycine concentrations. Homomeric alpha 1 glycine receptors were more sensitive to the effects of ethanol than were alpha 2 or the mutant alpha 1(A52S) receptors. No differences were found in ethanol sensitivity between alpha 2 and the mutant alpha 1(A52S) receptors. The alpha 2 subunit has a threonine residue, a conservative substitution for serine, at amino acid 52. The general anesthetic propofol was also tested in homomeric alpha 1, alpha 2, or the mutant alpha 1(A52S) receptors. Propofol, at unaesthetic concentrations (1-5 microM), reversibly potentiated the glycine receptor function in a concentration-dependent manner and to an equal extent in the three subunits tested. These data suggest that the mutation of an alanine to serine at amino acid 52 of the alpha subunit is responsible for the difference in ethanol sensitivity seen in homomeric receptors composed of alpha 1 and alpha 2 subunits.
Mol Pharmacol 1996 Aug
PMID:A single amino acid determines differences in ethanol actions on strychnine-sensitive glycine receptors. 870 Jan 49

Sequential addition of vanadyl sulfate to a phosphate-buffered solution of H2O2 released oxygen only after the second batch of vanadyl. Ethanol added to such reaction mixtures progressively decreased oxygen release and increased oxygen consumption during oxidation of vanadyl by H2O2. Inclusion of ethanol after any of the three batches of vanadyl resulted in varying amounts of oxygen consumption, a property also shared by other alcohols (methanol, propanol and octanol). On increasing the concentration of ethanol, vanadyl sulfate or H2O2, both oxygen consumption and acetaldehyde formation increased progressively. Formation of acetaldehyde decreased with increase in the ratio of vanadyl:H2O2 above 2:1 and was undetectable with ethanol at 0.1 mM. The reaction mixture which was acidic in the absence of phosphate buffer (pH 7.0), released oxygen immediately after the first addition of vanadyl and also in presence of ethanol soon after initial rapid consumption of oxygen, with no accompanying acetaldehyde formation. The results underscore the importance of some vanadium complexes formed during vanadyl oxidation in the accompanying oxygen-transfer reactions.
Mol Cell Biochem 1996 Jan 26
PMID:Ethanol-dependent oxygen consumption and acetaldehyde formation during vanadyl oxidation by H2O2. 871 23

Ethanol-utilization in Aspergillus nidulans is mediated by alcohol dehydrogenase I and aldehyde dehydrogenase encoded by alcA and aldA, respectively. Both genes are under the transcriptional control of the specific activator AlcR and the general carbon catabolite repressor CreA. The alcR and alcA genes are closely linked in chromosome VII; aldA is located in chromosome VIII. We have identified five other transcripts that are expressed from the same genomic region as alcA and alcR. They are inducible by the gratuitous inducer ethyl methyl ketone (EMK), and are carbon catabolite repressed. The corresponding genes, designated alcM, alcS, alcO, alcP, and alcU, are differentially regulated by the specific transcriptional activator AlcR, and they are not all under the direct control by the CreA repressor. Some of the inducible transcripts are very abundant in the cell, whereas others are poorly expressed. Two sets of genes, alcM/alcS and alcR/alcO, are divergently transcribed and probably share a common cis-acting region, whereas alcP and alcU are individually transcribed from the same strand as alcA and alcR, and have their own promoters. The significance of the alc gene clustering is discussed. At least four of the five novel alc genes in the cluster are not essential for ethanol metabolism.
Mol Microbiol 1996 May
PMID:A newly identified gene cluster in Aspergillus nidulans comprises five novel genes localized in the alc region that are controlled both by the specific transactivator AlcR and the general carbon-catabolite repressor CreA. 873 27


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