Inactivation of alcohol and retinol dehydrogenases by acetaldehyde and formaldehyde.

The rapid and progressive inactivation of alcohol dehydrogenase from horse liver, rat liver and from human retina and of retinol dehydrogenase of rat liver by low concentrations of acetaldehyde or formaldehyde is illustrated. The inactivation of alcohol dehydrogenase can be largely prevented and partially reversed with glutathione. These findings are discussed as a model for better understanding of toxic effects of alcohol and in the context of the importance of protein turnover measurements for clarification of untoward alcohol effects.     

International Commission for Protection against Environmental Mutagens and Carcinogens. ICPEMC Working Paper No. 15/2. Metabolism and metabolic effects of ethanol, including interaction with drugs, carcinogens and nutrition

Different pathways of alcohol metabolism, the alcohol dehydrogenase pathway, the microsomal ethanol-oxidizing system and the catalase pathway are discussed. Alcohol consumption leads to accelerated ethanol metabolism by different mechanisms including an increased microsomal function. Microsomal induction leads to interactions of ethanol with drugs, hepatotoxic agents, steroids, vitamins and to an increased activation of mutagens/carcinogens. A number of ethanol-related complications may be explained by the production of its first metabolite, acetaldehyde, such as alterations of mitochondria, increased lipid peroxidation and microtubular alterations with its adverse effects on various cellular activities, including disturbances of cell division. Nutritional factors in alcoholics such as malnutrition are discussed especially with respect to its possible relation to cancer.     

Thermodynamic reversibility of phase transitions. Specific effects of alcohols on phosphatidylcholines

The gel-to-fluid phase transitions of several phosphatidylethanolamines (PE's) and phosphatidylcholines (PC's) have been investigated in the presence of three short-chain alcohols. The effects of the alcohols on the thermodynamic reversibility of these transitions was studied and it was found that the transitions for PC's are not thermodynamically reversible at relatively high alcohol concentrations. The PE transitions are thermodynamically reversible for all alcohol concentrations, and the PE's do not exhibit the biphasic effects of alcohol on the transition temperature previously reported for the PC's (Rowe, E.S. (1983) Biochemistry 22, 3299-3305). The biphasic transition temperature effects and the thermodynamic irreversibility of PC transitions at high alcohol concentrations appear to be correlated with the induction of a fully interdigitated gel phase recently reported in the literature (Simon, S.A. and McIntosh, T.J. (1984) Biochim. Biophys. Acta 773, 169-172). The biological significance of these findings is discussed.     

Biophysical studies on subcellular particles VII. Combined effects of alcohol and heat on photosynthetic activities in isolated spinach chloroplasts

Isolated spinach chloroplasts were warmed for 5 min at temperaturesranging between 20? and 55?C in the presence of short-chainaliphatic alcohols, and their photosynthetic activities wereassayed. Tmax, the temperature at which ferricyanide reduction is stimulatedto a maximum extent, was lowered with an increase in the concentrationof alcohol or the chain-length of n-alcohols. Values also differedamong the structural isomers of an alcohol. The Tmax shift wasobserved only when alcohol was present in a chloroplast suspensionduring warming treatment, indicating that heat and alcohol wereacting together to lower the Tmax, at which the phosphorylationactivity fell to zero. The combined effects of alcohol and heat are discussed in connectionwith the lipophilic construction of thylakoids through the partitionco-efficient of individual alcohols between water and n-octylalcohol. (Received August 5, 1972; )     

Pathogenesis and management of alcoholic liver injury.

The present paper is devoted to overview the basic concepts of ethanol-induced hepatic injury and therapeutic modalities by which alcoholic liver disease can be alleviated. The role of alcohol dehydrogenase of both hepatic and gastric origin as well as the importance of the number one metabolite acetaldehyde are discussed, furthermore the effects of microsomal ethanol oxidizing system are also described. The features of the major clinicopathological consequences of alcohol abuse fatty liver, alcoholic hepatitis are briefly outlined, and the basic pathogenetic mechanisms that lead to cirrhosis--cell necrosis, regeneration and fibroplasia--are shown. The understanding of the pathophysiology of alcohol-induced liver injury may improve the therapy with drugs and nutritional factors, and allow successful prevention through the early recognition of heavy drinkers before their social or medical disintegration. In the management of alcoholic liver diseases, among the true hepatoprotective agents a naturally occurring flavonoid silymarin and an active methyl-donor metabolite S-adenosyl-L-methionine seem to be promising. An antifibrotic treatment with colchicine might also be of importance. Further prospective, well-designed, controlled clinical trials are still warranted to evaluate real efficacy of these drugs. The hepatic consequences of alcohol abuse may be treatable, however, prevention would be the true resolution of the major global health problem of alcoholism.     

Variation in the direction of selection applied by pentenol to the alcohol dehydrogenase locus in Drosophila melanogaster.

This paper describes selective effects of pentenol-impregnated media on six genotypes at the alcohol dehydrogenase (Adh) locus in D. melanogaster. In the laboratory population studied, developmental times of pre-adults homozygous for an alcohol dehydrogenase "null" allele increased with increasing pentenol concentrations. The developmental times of the other five genotypes, which produced active alcohol dehydrogenases, increased slightly at pentenol concentrations up to 0-0033%, but above this concentration they decreased markedly. In fact on 0-067% pentenol, the highest concentration tested, developmental times of these five genotypes were between 9 and 24 h less than their developmental times on media lacking pentenol. The magnitude of the reduction in developmental time differed significantly between genotypes and was positively correlated with alcohol dehydrogenase activity. Pentenol had toxic effects on adults and significant differences were found between survival percentages of adults of different genotypes on pentenol-impregnated media. These survival percentages were negatively correlated with alcohol dehydrogenase activities. Therefore selective differences between genotypes in adult survival were negatively correlated with those in developmental times. The variations in the direction of selection are discussed in terms of their possible biochemical basis and their effects on the maintenance of Adh polymorphisms.     

Kinetic and mechanistic studies of methylated liver alcohol dehydrogenase.

Reductive methylation of lysine residues activates liver alcohol dehydrogenase in the oxidation of primary alcohols, but decreases the activity of the enzyme towards secondary alcohols. The modification also desensitizes the dehydrogenase to substrate inhibition at high alcohol concentrations. Steady-state kinetic studies of methylated liver alcohol dehydrogenase over a wide range of alcohol concentrations suggest that alcohol oxidation proceeds via a random addition of coenzyme and substrate with a pathway for the formation of the productive enzyme-NADH-alcohol complex. To facilitate the analyses of the effects of methylation on liver alcohol dehydrogenase and factors affecting them, new operational kinetic parameters to describe the results at high substrate concentration were introduced. The changes in the dehydrogenase activity on alkylation were found to be associated with changes in the maximum velocities that are affected by the hydrophobicity of alkyl groups introduced at lysine residues. The desensitization of alkylated liver alcohol dehydrogenase to substrate inhibition is identified with a decrease in inhibitory Michaelis constants for alcohols and this is favoured by the steric effects of substituents at the lysine residues.     

Enzymes of the mandelate pathway in bacterium N.C.I.B. 8250

1. Bacterium N.C.I.B. 8250 was grown on dl-mandelate, benzyl alcohol, benzoyl-formate, benzaldehyde and benzoate and also on 2-hydroxy, 4-hydroxy, 3,4-dihydroxy and 4-hydroxy-3-methoxy analogues of these compounds. The enzymic complements of the cells were determined and the specificities of some of the enzymes examined. 2. Growth on mandelate or benzoylformate induces l-mandelate dehydrogenase, benzoylformate decarboxylase, benzyl alcohol dehydrogenase and a heat-stable as well as a heat-labile benzaldehyde dehydrogenase. Growth on benzyl alcohol or benzaldehyde induces benzyl alcohol dehydrogenase and the heat-labile benzaldehyde dehydrogenase. 3. The enzymes of the mandelate-to-benzoate pathway are non-specifically active on, and induced by, all the substituted analogues that support growth. 4. Benzoate oxidase is induced by growth on benzoate or on 2-hydroxybenzoate. 2-Hydroxybenzoate hydroxylase, 4-hydroxybenzoate hydroxylase and 4-hydroxy-3-methoxybenzoate O-demethylase are induced only by growth on homologous substrates. 5. The results of the investigation are discussed with regard to the possible regulation of the enzyme systems.     

Alcohol-oxidizing enzymes from various organisms.

1. Enzymes that catalyse the oxidation of aliphatic alcohols to aldehydes are reviewed. 2. Special attention is given to phenazine methosulphate-linked alcohol dehydrogenases from bacteria and to flavin-containing alcohol oxidases from yeasts, moulds and higher plants. 3. Some properties of the microsomal ethanol-oxidative system of rat liver are discussed.     

Effects of alcohol on the fetus: impact and prevention.

In the spectrum of adverse effects on the fetus or infant associated with maternal drinking during pregnancy the most dramatic is the fetal alcohol syndrome, a pattern of malformation that has been associated with maternal alcohol abuse. Other undesirable outcomes of pregnancy linked to alcohol exposure in utero include growth deficiency, major and minor anomalies, decrements in mental and motor performance, and fetal and perinatal wastage. Alcohol, like other teratogens, does not uniformly affect all those exposed to it. Rather, there seems to be a continuum of effects of alcohol on the fetus with increasingly severe outcomes generally associated with higher intakes of alcohol by the mother. The cost of fetal damage associated with alcohol exposure is very high. A program to decrease the incidence of fetal alcohol effects is therefore imperative. The cornerstone of such a program must be not only education of the public but also careful training of all professionals who provide health care for pregnant women.     

Hepatic alcohol oxidation and its metabolic liability.

The pathways responsible for ethanol oxidation and the toxic results of its metabolism are reviewed. The predominant pathway for ethanol oxidation at low ethanol concentrations involves alcohol dehydrogenase. However, at high alcohol concentrations, up to 50% of ethanol uptake is 4-methylpyrazole-intensitive. Oxidation of ethanol under these conditions is associated with a change in the steady-stage concentration of catalase-H2O2. Based on recent evidence, we conclude that it is unnecessary to postulate that ethanol is oxidized directly via cytochrome P-450. Acetaldehyde production from ethanol via the microsomal subfraction can be accounted for by the combined activities of catalase-H2O2 and alcohol dehydrogenase. The metabolism of ehtanol via alcohol dehydrogenase produces a marked reduction in the hepatocellular NAD-NADH sytems. This reduction is indirectly responsible for the inhibition of glycolysis, gluconeogenesis, citric acid cycle activity, and fatty acid oxidation and may be related to some of the pathological effects observed following chronic consumption of alcohol. Attempts in inhibit alcohol dehydrogenase with alkylpyrazoles and activate catalase with substrates for peroxisomal H2O2-generating flavoproteins, while successful, may have limited applicability because of the native toxicity of the substrates themselves...     

International Commission for Protection against Environmental Mutagens and Carcinogens. ICPEMC Working Paper No. 15/3. Human acetaldehyde levels: aspects of current interest

The determination of acetaldehyde levels in blood and other tissues is a difficult task, and depends on the method used. Different methods and their pros and cons are discussed in detail. Quantitative results are shown for endogenous acetaldehyde levels and for acetaldehyde levels during alcohol intoxication. One article pertains to acetaldehyde bound to blood and tissue proteins.     

Moving Targets: Modeling Developmental Trajectories of Adolescent Alcohol Misuse,Individual and Peer Risk Factors,and Intervention Effects

From a developmental perspective, a central goal of prevention is to alter behaviors that are already changing-that is, to redirect potentially risky trajectories. This multiwave panel study examines the longer-term effects of a prevention program on trajectories of alcohol misuse and related risk factors (susceptibility to peer pressure to misbehave and exposure to peer alcohol use). We conceptually and empirically compare Hierarchical Linear Modeling (HLM) and Latent Growth Curve Modeling (LCM), working within the tradition of each technique and noting similarities and differences in approaches, hypothesis operationalizations, and findings. Five waves of data (Grades 6 to 10, n = 675) from the Alcohol Misuse Prevention Study, a randomized treatment-control group study designed to examine the effects of a school-based prevention program that focused on increasing social (especially refusal) skills, were analyzed. HLM and LCM analyses showed susceptibility, exposure, and alcohol misuse increased mostly linearly across adolescence and covaried positively within and across time, arguing that they exist in a mutually reinforcing web of influence. Both techniques revealed small treatment effects, with the prevention reducing the normative increase in alcohol misuse during adolescence. There were some minor, but important, differences between HLM and LCM in conclusions about intervention effects. Substantive and developmental methodological implications are discussed.     

A decrease in the acute toxicity of ethanol produced by zinc sulfate

It was shown that zinc sulphate injection during the acute alcohol intoxication resulted in the decrease of anaesthetic and toxic effects of ethanol. The most effective dose was 15 mkg/kg i.p. The possible mechanisms are discussed.     

Alcohol and ischaemic heart disease in middle aged British men.

The relation between alcohol intake and ischaemic heart disease was examined in a large scale prospective study of middle aged men drawn from general practices in 24 British towns. After an average follow up of 6.2 years 335 of the 7729 men had experienced a myocardial infarction (fatal or non-fatal) or sudden cardiac death. No significant relation was found between reported alcohol intake and the incidence of such events. Though the group of light daily drinkers had the lowest incidence of ischaemic heart disease events, it also contained the lowest proportion of current smokers, had the lowest mean blood pressure, had the lowest mean body mass index, and contained the lowest proportion of manual workers. These characteristics are more likely to account for the apparent protective effect of alcohol against ischaemic heart disease than a direct effect of alcohol. Compared with the effects of established risk factors alcohol seems to be quite unimportant in the development of ischaemic heart disease.     

Carboxymethylated liver alcohol dehydrogenase. Transient kinetic studies and effect of substrate structure on alcohol oxidation.

1. The rate constants for NADH binding and dissociation for carboxymethylated alcohol dehydrogenase have been determined and compared to those for the native enzyme. 2. Steady-state and transient kinetic experiments have shown that the hydrogen transfer step is rate-determining for oxidation of ethanol by carboxymethylated alcohol dehydrogenase. The rate constant of 0.19 s-1 is considerably slower than that for the native enzyme. 3. The steady-state parameter, V/[E], was obtained for each of a series of alcohols and correlated with the Taft sigma parameter. The linear relationship obtained indicates that the same step, hydrogen transfer, is rate-determining for all the alcohols. The sigma value obtained is the same as for the native enzyme; the implications of this for the mechanism of hydrogen transfer are discussed.     

The activity of glucagon-stimulated adenylate cyclase from rat liver plasma membranes is modulated by the fluidity of its lipid environment.

1. The local anaesthetic benzyl alcohol progressively activated glucagon-stimulated adenylate cyclase activity up to a maximum at 50 mM-benzyl alcohol. Further increases in benzyl alcohol concentration inhibited the activity. The fluoride-stimulated adenylate cyclase activity was similarly affected except for an inhibition of activity occurring at low benzyl alcohol concentrations (approx. 10 mM. 2. The fluoride-stimulated adenylate cyclase activity of a solubilized enzyme preparation was unaffected by any of the benzyl alcohol concentrations tested. 3. Increases in 3-phenylpropan-1-ol and 5-phenylpentan-1-ol concentrations progressively activated both the fluoride- and glucagon-stimulated adenylate cyclase activities up to a maximum, above which further increases in alcohol concentration inhibited the activities. 4. The 'break' points in Arrhenius plots of glucagon-stimulated adenylate cyclase activity in native plasma membranes, and in plasma membranes fused with synthetic dimyristoyl phosphatidylcholine so as to constitute 60% of the total lipid pool, were decreased by approx. 6 degrees C by addition of 40 mM-benzyl alcohol. This was accompanied by a fall in the associated activation energies. 6. Arrhenius plots of fluoride-stimulated adenylate cyclase activity in the presence and absence of 40 mM-benzyl alcohol were linear, although addition of benzyl alcohol caused a dramatic decrease in the associated activation energy of the reaction. 7. 5'-Nucleotidase activity was stimulated by benzyl alcohol, and the 'break' point in the Arrhenius plot of its activity was decreased by about 6 degrees C by addition of 40 mM-benzyl alcohol to the assay. 8. It is suggested that benzyl alcohol effects a fluidization of the bilayer, which is clearly demonstrated by its ability to lower the temperature of a lipid phase separation occurring at 28 degrees C in the outer half of the bilayer to around 22 degrees C. The increase in bilayer fluidity relieves a physical constraint on the membrane-bound adenylate cyclase, activating the enzyme. 9. The various inhibition phenomena are discussed in detail, together with the suggestion that the interaction between the uncoupled catalytic unit of adenylate cyclase and the lipids of the bilayer is altered on its physical coupling to the glucagon receptor.     

Alcohol Tax Policy and Related Mortality. An Age-Period-Cohort Analysis of a Rapidly Developed Chinese Population, 1981–2010

To delineate the temporal dynamics between alcohol tax policy changes and related health outcomes, this study examined the age, period and cohort effects on alcohol-related mortality in relation to changes in government alcohol policies. We used the age-period-cohort modeling to analyze retrospective mortality data over 30 years from 1981 to 2010 in a rapidly developed Chinese population, Hong Kong. Alcohol-related mortality from 1) chronic causes, 2) acute causes, 3) all (chronic+acute) causes and 4) causes 100% attributable to alcohol, as defined according to the Alcohol-Related Disease Impact (ARDI) criteria developed by the US Centers for Disease Control and Prevention, were examined. The findings illustrated the possible effects of alcohol policy changes on adult alcohol-related mortality. The age-standardized mortality trends were generally in decline, with fluctuations that coincided with the timing of the alcohol policy changes. The age-period-cohort analyses demonstrated possible temporal dynamics between alcohol policy changes and alcohol-related mortality through the period effects, and also generational impact of alcohol policy changes through the cohort effects. Based on the illustrated association between the dramatic increase of alcohol imports in the mid-1980s and the increased alcohol-related mortality risk of the generations coming of age of majority at that time, attention should be paid to generations coming of drinking age during the 2007–2008 duty reduction.     

Results of prenatal alcohol exposure on the dimensions and binucleation of cardiac myocytes in neonatal and weanling rats

Sprague-Dawley rats were exposed to ethyl alcohol in utero. The effect of chronic prenatal exposure was examined by giving mature females alcohol in isocaloric liquid diets which served as the sole source of liquid and caloric intake before mating and throughout gestation. Controls consisted of females maintained on laboratory chow or an isocaloric liquid diet minus alcohol before and during gestation. The offspring were sacrificed at 21 days of age (weanlings) and the hearts dissociated enzymatically to give purified cardiac myocytes. The effects of daily acute prenatal alcohol exposure were studied by gastric intubation of alcohol to chow-fed females for the duration of pregnancy. The doses used approximated 4 and 5 shots of 80 proof liquor per day by a person weighing 150 lb. These offspring were sacrificed at 2, 6, and 21 days postnatal and cardiac myocytes prepared as above. Heart weights were determined and cardiac myocytes were analyzed for cell length, volume, cross-sectional area, and percent binucleation. Additionally, nuclear DNA content was measured in all of the 21 day offspring. Statistical analysis of the data showed no significant differences between hearts exposed to prenatal alcohol and nonexposed controls with either regimen with the exception of percent binucleation which was significantly but only slightly higher in the 6-day-old hearts. These findings are discussed in relation to anatomical heart defects found in patients with full fetal alcohol syndrome.     

Ethanol fermentation and potential.

Ethyl alcohol is one of the United States and world's major chemicals. Beverage alcohol in the United States must be prepared from cereal grains or other natural products. The U.S. industrial alcohol market has remained relatively stable for several years at approximately 300 million gallons annually. Most of this has been produced synthetically from petroleum raw material (gas and oil). These raw materials are experiencing major price increases and are in short supply. The production of ethyl alcohol from cereal grains and cellulosic raw materials by fermentation is technically feasible and has been proven. Alcohol produced from all such materials is equal to synthetic alcohol in quality and performance. Competitive economics have controlled the basic raw materials used. The major potential new ethyl alcohol market is as a component of automobile fuels. A 10% alcohol-gasoline blend in the United States would annually require over 10 billion gallons of anhydrous alcohol. Use of alcohol for this purpose is technically feasible. However, alcohol has not been economically competitive to date.