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Query: UMLS:C1332347 (ADH)
 2,230 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Concomitant findings of isopropanol and acetone in biospecimens of decedents known not to have been exposed to the alcohol prompted a study to explain its origins. Mixtures of acetone, ADH, and NADH at pHs 7.3 and 8.8 were incubated at 37 degrees C for varying intervals. Reaction products were then analyzed by headspace GC and assured identification made by GC/MS. It was found that isopropanol is produced by reduction of acetone at pH 7.3 (to a lesser extent at pH 8.8), providing evidence for an alternate metabolic route for acetone. A mechanism for this reduction is proposed. Ranges for isopropanol (in mg/dL or mg/100 g) found in unexposed decedents were: blood 1-29; liver 7-59; brain 2-12; kidney 6-26. Thus, the forensic investigator must interpret isopropanol results cautiously, particularly when low concentrations are found.
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PMID:Endogenous isopropanol: forensic and biochemical implications. 638 78

1. The redox state of mitochondrial NAD was monitored fluorometrically as a function of active ion transport work in the isolated doubly perfused bullfrog kidney. 2. Initial experiments to measure the O2 consumption (QO2) of small pieces from the bullfrog kidney gave a basal QO2 - 3.0 (+/- 0.43) nmoles O2/mg dry wt. min. Addition of 50 microM-ouabain inhibited QO2 by 72.7%. Subsequent addition of the mitochondrial uncoupler 1799 stimulated QO2 by 226%, while cyanide totally inhibited respiration. 3. Ion transport functional parameters and NADH fluorescence were simultaneously monitored during systematic reductions in perfusate PO2 to test the sufficiency of O2 delivery to the isolated perfused frog kidney. No significant changes in transport functions or fluorescence were observed until the PO2 dropped to 184 mm Hg or below. O2 tensions of 184 mm Hg or below caused decreases in G.F.R. and transport functions which were accompanied by an increase in NADH fluorescence. The lack of changes in kidney function in the PO2 range 550-340 mmHg suggested that the tissue is adequately oxygenated at the normal perfusate PO2 of 550 mmHg. 4. The relationship between active transport rate and NAD redox levels was studied by increasing transport work (via increased G.F.R. or ADH) or by decreasing transport work (via decreased G.F.R. or ouabain) while simultaneously monitoring the NAD redox state of the intact tissue fluorometrically. In all cases, an increase in work caused a net oxidation of NAD while a decrease in work caused a reduction of NAD. 5. It is concluded that the NADH fluorescence responses are indicative of mitochondrial active to passive transitions in response to changes in active transport work. The aerobic production of ATP and the normally functioning Na-K-ATPase appear to be essential to maintain active transport and to elicit the appropriate state transitions. Thus, ATP (and, possibly, ADP and Pi) may be part of the coupling mechanism linking active ion transport and aerobic metabolic rate in the kidney.
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PMID:Coupling of aerobic metabolism to active ion transport in the kidney. 696 4

A general survey of the ethanol metabolism and the sequels resulting from this of different kind and intensiveness is given. The speed of the absorption of ethanol is determined according to the laws of diffusion above all by dose and concentration of the ethanol taken. The duration corresponding to the facts varies in broad limits between 10 and 180 min. Nearly simultaneously with the absorption the distribution of the ethanol into the tissues takes place. According to its overwhelming water solubility the ethanol content of the individual tissues is of different size when a distribution balance developed. Three enzyme systems independent of each other, the ADH, the MEOS and the katalase participate in the elimination of the ethanol, the maximum speed of degradation of which lies at the in every case different values of blood alcohol. These three enzyme systems further differ by various localisation, inhibitors, coferments, beginning of activity, optimum of activity and adaptive induction to ethanol. Demarcating for the first step of degradation and thus finally of the ethanol degradation in general might probably be the reoxydation rate, particularly of the NADH, and its repeated inclusion into the ethanol metabolism. Chronic intake of alcohol has multiple effects, among others due to the perhaps temporarily limited adaptive induction of MEOS it has altogether higher rates of degradation. These again have numerous negative sequels with sensitive disturbance of numerous physiologic processes of the intermediary metabolism, in which cases through functional processes finally result organic changes of different kind.
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PMID:[Clinically relevant aspects of ethanol metabolism]. 702 48

Selection of petite strains of yeast (that is, strains unable to respire aerobically) on media containing allyl alcohol will result in enrichment for mutants at the ADC1 locus. This locus codes for the constitutive alcohol dehydrogenase, ADH-I, which is primarily responsible for the production of ethanol in yeast. The mutant enzymes are functional, and confer resistance to allyl alcohol on the cell by shifting the NAD-NADH balance in the direction of NADH. These mutants exhibit altered Km's for cofactor, substrate, or both, and often have altered Vmax's. In this paper, the methodology for obtaining these mutants and for determining the amino acid substitutions responsible for these changes is presented. Several new mutants have been at least approximately localized, and one, DB-AA3-N15, has been shown to be due to the substitution of an arginine for a tryptophan at position 54. This substitution would be expected, by analogy with the known tertiary structure of the horse liver alcohol dehydrogenase, to decrease the hydrophobic environment of the active site pocket. The substitution has a pronounced effect on the Km for ethanol, but far less on that for acetaldehyde. The current status of investigation of other classes of functional mutants of this enzyme, and the potential both for selection of useful variants of this molecule and for an increase understanding of its function are discussed.
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PMID:Functional mutants of yeast alcohol dehydrogenase. 703

The effects of the various naturally occurring amino acids on ethanol oxidation in hepatocytes from 18-hrs starved and fed rats were studied. In order to minimize the non-ADH pathways and to avoid interference with the liver amino acid uptake the ethanol concentration used was 4 mM, the amino acids being added at the same concentration. In hepatocytes from starved rats, asparagine, serine, ornithine, hydroxyproline, histidine, cysteine, alanine, glycine, glutamate, glutamine, aspartate and arginine significantly increase ethanol consumption. The stimulatory effect of glutamine being much less pronounced than the asparagine one and proline being devoid of action, the influence of ammonium chloride addition on ethanol consumption in the presence of these amino acids was studied. Ammonium chloride determines an enhancement of ethanol oxidation, the results showing, contrarily to previous data, no apparent correlation between intracellular glutamate concentration and ethanol oxidation rate but rather a relation with aspartate concentration. In hepatocytes from fed rats alanine, asparagine, cysteine, glycine, hydroxyproline, ornithine and serine still increase ethanol oxidation, although to a lesser extent than in cells from starved rats. It appears that only amino acids which are precursors of either pyruvate or aspartate or glutamate are able to activate the ethanol oxidation. Pyruvate, aspartate and glutamate supply malate-aspartate shuttle components especially in cells from starved rats, pyruvate allowing direct cytosolic reoxidation of NADH in cells from fed rats as well as from starved rats. The relative strengths of the stimulatory effect could be roughly dependent on energy demand for glucose synthesis in starved rats and for urea synthesis in fed rats.
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PMID:Comparative study of the effect of amino acids on ethanol oxidation in isolated hepatocytes from starved and fed rats. 742 19

Fasting produces a decrease in ethanol elimination rate of as much as 40% in rats and hamsters. In order to identify the biochemical process responsible for this change, the maximal activity of ADH, the cytosolic free NAD+/NADH ratio and the concentration of ethanol and acetaldehyde in liver were measured in both fed and 48 h fasted rats and hamsters after ethanol administration. While the maximal ADH activity of liver decreased 40% or more with fasting, only a small difference in NAD+/NADH ratio was observed between fed and fasted animals both 1 and 2 h following the administration of ethanol. Calculations of the steady-state rates of oxidation of ethanol by rat ADH revealed that the enzyme is rate-limited primarily by the concentration of free NAD+ in cytosol but that the steady-state rates of ethanol oxidation by ADH are 80-90% of the in vivo ethanol elimination rates. With fasting, the percentage decrease in steady-state rates was identical to that for ADH activity and for the in vivo elimination rate. These results indicate that changes in rates of oxidation of NADH and acetaldehyde contribute little toward the decrease in ethanol elimination rate associated with fasting but that the change in liver ADH activity or content is primarily responsible.
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PMID:Rate-determining factors for ethanol metabolism in vivo during fasting. 742 28

Gastric intubation of female Sprague-Dawley rats (80-150 g) with one large dose (5 g/kg) of ethanol nearly doubled oxygen uptake of the isolated, perfused rat liver in only 2.5 hours. This increased hepatic respiration can account for the Swift Increase in Alcohol Metabolism (SIAM). Inhibition of enhanced oxygen and ethanol uptake by KCN (2 mM) and 4-methylpyrazole (0.8 mM) indicated the involvement of the mitochondrial respiratory chain and alcohol dehydrogenase in this phenomenon, respectively. Epinephrine (2 mg/kg, i.p.) mimicked the increase in respiration observed with ethanol; however, the effects of epinephrine and ethanol were not additive. Pretreatment with alpha- and beta-adrenergic blocking agents, hypophysectomy and adrenalectomy prevented the increase in oxygen and ethanol uptake due to ethanol treatment. These data suggest that hormones including epinephrine are involved in the mechanism of SIAM. Hormone action in all likelihood activates a number of metabolic ATPase activities which lead to elevated oxygen uptake. One such process involved in the activation of oxygen uptake is diminished glycolysis, a ATP producing reaction sequence. The ADP not phosphorylated in the cytosol then enters the mitochondria where it stimulates oxygen uptake and NADH reoxidation. This ultimately leads to an acceleration of ADH-dependent ethanol metabolism.
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PMID:Mechanism of the swift increase in alcohol metabolism ("SIAM") in the rat. 742 36

The ability of Drosophila alcohol dehydrogenase (D-ADH) to catalyze the oxidation of aldehydes to carboxylic acids has been re-examined. Prior studies are shown to have been compromised by a nonenzymic reaction between the aldehydic substrates and amine-containing buffers, e.g., glycine or Tris, and an amine-catalyzed addition of aldehyde to NAD+. These reactions interfere with spectrophotometric assays for monitoring aldehyde oxidation and obscure the nature and scope of D-ADH-catalyzed aldehyde oxidation, particularly at physiological pH. Use of nonreactive buffers, such as pyrophosphate or phosphate, and 1H NMR spectroscopy to monitor all the components of the reaction mixture reveals the facile dismutation of aldehydes into equimolar quantities of the corresponding acids and alcohols at both neutral and high pH. At high pH, dismutation is accompanied by a small burst of NADH production to a steady-state concentration ( < 10 microM) that represents a partitioning between NADH dissociation and aldehyde reduction. The increase in A340 is therefore not a direct measure of the aldehyde oxidation reaction, and the resulting kinetic values cannot be compared to those for alcohol dehydrogenation. The present results for D-ADH, combined with data from the literature, establish that aldehyde oxidation, manifest as dismutation, is a widespread property of alcohol dehydrogenases with potential physiological importance in alcohol metabolism and aldehyde detoxification.
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PMID:Aldehyde dehydrogenase activity of Drosophila melanogaster alcohol dehydrogenase: burst kinetics at high pH and aldehyde dismutase activity at physiological pH. 754 72

Weight gain efficiency differences previously reported between alcohol-fed rats and their controls were investigated. Additionally, the futile cycling of ethanol proposed to explain such differences was studied by NMR spectroscopy. Male Sprague-Dawley rats were fed a nutritionally adequate diet containing 36% of the calories as alcohol, and their paired controls were fed an isocaloric diet for 11 weeks to establish conditions of chronic alcohol feeding. Normalized metabolic efficiencies varied significantly during the initial 2-week period (6.86 +/- 0.51 vs. 2.83 +/- 0.18 g/kcal x 10(-2) for control and alcohol-fed groups, respectively, and to a lesser extent over the entire feeding period (6.41 +/- 0.78 vs. 4.60 +/- 0.27 g/kcal x 10(-2) for control and alcohol-fed groups, respectively. Alcohol-induced weight gain inefficiency in metabolism has previously been studied and explained by a variety of different biochemical and physiological mechanisms. One possible pathway of energy wastage may occur due to ethanol futile cycling from ethanol to acetaldehyde through the microsomal ethanol oxidation system pathway, and simultaneously from acetaldehyde to ethanol via the ADH pathway. This futile cycle represents a net loss of 6 ATP/cycle, corresponding to the loss of two reducing equivalents (NADH and NADPH). 1H NMR spectroscopy was used to test for this cycling in blood extracts after administration of 1,1-2H2 ethanol. No futile cycling was detected either during the initial 2 weeks of feeding or after the entire feeding period.
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PMID:NMR investigation of the futile cycling of ethanol in chronic alcoholic rats. 769 33

Stressed plant cells often show increased oxygen uptake which can manifest itself in the transient production of active oxygen species, the oxidative burst. There is a lack of information on the redox status of cells during the early stages of biotic stress. In this paper we measure oxygen uptake and the levels of redox intermediates NAD/NADH and ATP and show the transient induction of the marker enzyme for redox stress, alcohol dehydrogenase. Rapid changes in the redox potential of elicitor-treated suspension cultures of French bean cells indicate that, paradoxically, during the period of maximum oxygen uptake the levels of ATP and the NADH/NAD ratio fall in a way that indicates the occurrence of stress in oxidative metabolism. This period coincides with the maximum production of active oxygen species particularly H2O2. The cells recover and start producing ATP immediately of H2O2 production. This indicates that the increased O2 uptake is primarily incorporated into active O2 species. A second consequence of these changes is probably a transient compromising of the respiratory status of the cells as indicated in expression of alcohol dehydrogenase. Elicitor-induced bean ADH was purified to homogeneity and the M(r) 40,000 polypeptide was subjected to amino acid sequencing. 15% of the whole protein was sequenced from three peptides and was found to have nearly 100% sequence similarity to the amino acid sequence for pea ADH1 (PSADH1). The cDNA coding for the pea enzyme was used to demonstrate the transient induction of ADH mRNA in elicitor-treated bean cells. Enzyme activity levels also increased transiently subsequently. Increased oxygen uptake has previously been thought to be associated with provision of energy for the changes in biosynthesis that occur rapidly after perception of the stress signal. However the present work shows that this rapid increase in oxygen uptake as a consequence of elicitor action is not wholly associated with respiration.
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PMID:Rapid changes in oxidative metabolism as a consequence of elicitor treatment of suspension-cultured cells of French bean (Phaseolus vulgaris L.). 786 96


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