Polymorphism of aldehyde dehydrogenase and ethanol elimination

Relationships of habitual daily alcohol consumption with all-day and time-specific average glucose levels among non-diabetic population samples

BACKGROUND

Alcohol consumption is a prevalent behavior that is bi-directionally related to the risk of type 2 diabetes. However, the effect of daily alcohol consumption on glucose levels in real-world situations in the general population has not been well elucidated. This study aimed to clarify the relationship between alcohol consumption and all-day and time-specific glucose levels among non-diabetic individuals.

METHODS

We investigated 913 non-diabetic males and females, aged 40-69 years, during 2018-2020 from four communities across Japan. The daily alcohol consumption was assessed using a self-report questionnaire. All-day and time-specific average glucose levels were estimated from the interstitial glucose concentrations measured using the Flash glucose monitoring system for a median duration of 13 days. Furthermore, we investigated the association between all-day and time-specific average glucose levels and habitual daily alcohol consumption levels, using never drinkers as the reference, and performed multiple linear regression analyses after adjusting for age, community, and other diabetes risk factors for males and females separately.

RESULTS

All-day average glucose levels did not vary according to alcohol consumption categories in both males and females. However, for males, the average glucose levels between 5:00 and 11:00 h and between 11:00 and 17:00 h were higher in moderate and heavy drinkers than in never drinkers, with the difference values of 4.6 and 4.7 mg/dL for moderate drinkers, and 5.7 and 6.8 mg/dL for heavy drinkers. Conversely, the average glucose levels between 17:00 and 24:00 h were lower in male moderate and heavy drinkers and female current drinkers than in never drinkers; the difference values of mean glucose levels were -5.8 for moderate drinkers, and -6.1 mg/dL for heavy drinkers in males and -2.7 mg/dL for female current drinkers.

CONCLUSIONS

Alcohol consumption was associated with glucose levels in a time-dependent biphasic pattern.

Validity and reliability of a driving simulator for evaluating the influence of medicinal drugs on driving performance

RATIONALE

Although driving simulators (DS) are receiving increasing attention due to concern over traffic accidents under the influences of drugs, few DS are recognized for their reliability and validity. Therefore, the development of an evaluation system using DS for driving performance is urgently needed.

OBJECTIVES

To investigate whether the standard deviation of lateral position (SDLP) increases with blood alcohol concentration (BAC) using a DS with reliability and calculate the SDLP threshold from the difference between BAC levels of 0 and 0.05%.

METHODS

Twenty healthy Japanese men performed the DS tasks up to 60 min in Study 1 and DS tasks twice at 1-week intervals in Study 2. Twenty-six healthy men conducted the same DS tasks under BAC level (0, 0.025, 0.05, and 0.09%) in double-blind, randomized, crossover trial in Study 3. The primary outcome was SDLP in a road-tracking test. The test-retest reliability of DS data was assessed, and the estimated difference in SDLP between BAC levels of 0 and 0.05% was calculated using a linear regression model.

RESULTS

The cumulative SDLP values at 5-min intervals were stable, and the intraclass correlation coefficient for its values was 0.93. SDLP increased with BAC in a concentration-dependent manner. The predicted ΔSDLP value for the difference between BAC levels of 0 and 0.05% was 9.23 cm. No participants dropped out because of simulator sickness.

CONCLUSIONS

The new DS used in these studies has reliability, validity, and tolerability and is considered suitable for evaluating the influence of drugs on driving performance.

Dosage scaling of alcohol in binge exposure models in mice: An empirical assessment of the relationship between dose, alcohol exposure, and peak blood concentrations in humans and mice

Binge drinking is a remarkably prevalent behavior. In 2015, 27% of U.S. residents 18 years old or older reported at least one episode of binge drinking in the previous month. Rodent models for binge drinking are widely used to study the mechanisms by which alcohol causes a variety of adverse health effects in humans. Concerns have been raised that many binge-drinking studies in rodents involve alcohol doses that would be unrealistically high in humans. Allometric dosage scaling can be used to estimate the dose of a drug or chemical in mice that would be necessary to achieve similar biological effects at a realistic dose in humans. However, it has become apparent that no single allometric conversion factor is applicable for all drugs and chemicals, so it is necessary to evaluate each compound empirically. In the present study, we compared the area under the blood alcohol concentration vs. time curve (AUC) and the peak blood alcohol concentration following oral alcohol administration at various doses in mice and humans, using data from previously published studies. The results demonstrated that the oral dose of alcohol must be larger in mice (on a g of alcohol to kg of body weight basis) than in humans to achieve similar alcohol AUC values or to achieve similar peak concentrations in the blood. The dose required in mice was about 2-fold greater than the dose required in humans to achieve similar alcohol AUC and peak concentrations. The results shown here were substantially different from the average 5-12-fold difference between mice and humans calculated in previous studies using agents other than alcohol. Results shown here demonstrate that an empirical approach using data from several independent experiments provides information needed to determine the alcohol dose in mice that produces a similar level of exposure (AUC and peak concentration) as in humans. The results indicate that a single alcohol dose in the range of 5-6 g/kg, a range often used in mouse models for binge drinking, is not excessive when modeling human binge drinking. Results presented here illustrate that in mice both alcohol AUC and peak alcohol concentration correlate well with an important biological effect - activation of the hypothalamic-pituitary-adrenal axis - as indicated by increased corticosterone AUC values.

Pharmacokinetic analyses using absorption kinetics in low-alcohol dose cases of drunken driving

In Japan, low-alcohol dose cases of drunken driving, where drivers drink just before getting behind the wheel, are increasing for expert witnesses since the penalties for drunken driving have become stricter. Widmark's equation has generally been used for the pharmacokinetic analysis of blood alcohol concentration, which encompasses the one-compartment model with zero-order elimination kinetics but ignores absorption kinetics. We therefore propose that the formula might not be applicable to the analysis of low-alcohol dose cases of drunken driving because the issue is focused on the absorption phase. In this paper, we present two representative low-alcohol dose cases, which were analyzed using the one-compartment model with first-order absorption and zero-order elimination kinetics. This formula is thought to be more suitable and useful for medicolegal practice than Widmark's formula.

Effects of variation at the ALDH2 locus on alcohol metabolism, sensitivity, consumption, and dependence in Europeans

BACKGROUND

The low-activity variant of the aldehyde dehydrogenase 2 (ALDH2) gene found in East Asian populations leads to the alcohol flush reaction and reduces alcohol consumption and risk of alcohol dependence (AD). We have tested whether other polymorphisms in the ALDH2 gene have similar effects in people of European ancestry.

METHODS

Serial measurements of blood and breath alcohol, subjective intoxication, body sway, skin temperature, blood pressure, and pulse were obtained in 412 twins who took part in an alcohol challenge study. Participants provided data on alcohol reactions, alcohol consumption, and symptoms related to AD at the time of the study and subsequently. Haplotypes based on 5 single-nucleotide polymorphisms (SNPs) were used in tests of the effects of variation in the ALDH2 gene on alcohol metabolism and alcohol's effects.

RESULTS

The typed SNPs were in strong linkage disequilibrium and 2 complementary haplotypes comprised 83% of those observed. Significant effects of ALDH2 haplotype were observed for breath alcohol concentration, with similar but smaller and nonsignificant effects on blood alcohol. Haplotype-related variation in responses to alcohol, and reported alcohol consumption, was small and not consistently in the direction predicted by the effects on alcohol concentrations.

CONCLUSIONS

Genetic variation in ALDH2 affects alcohol metabolism in Europeans. However, the data do not support the hypothesis that this leads to effects on alcohol sensitivity, consumption, or risk of dependence.

Human variability for metabolic pathways with limited data (CYP2A6, CYP2C9, CYP2E1, ADH, esterases, glycine and sulphate conjugation)

Human variability in the kinetics of a number of phase I (CYP2A6, CYP2C9, CYP2E1, alcohol dehydrogenase and hydrolysis) and phase II enzymes (glycine and sulphate conjugation) was analysed using probe substrates metabolised extensively (>60%) by these routes. Published pharmacokinetic studies (after oral and intravenous dosing) in healthy adults and available data on subgroups of the population (effects of ethnicity, age and disease) were abstracted using parameters relating primarily to chronic exposure [metabolic and total clearances, area under the plasma concentration time-curve (AUC)] and acute exposure (C(max)). Interindividual differences in kinetics for all these pathways were low in healthy adults ranging from 21 to 34%. Pathway-related uncertainty factors to cover the 95th, 97.5th and 99th centiles of healthy adults were derived for each metabolic route and were all below the 3.16 kinetic default uncertainty factor in healthy adults, with the possible exception of CYP2C9*3/*3 poor metabolisers (based on a very limited number of subjects). Previous analyses of other pathways have shown that neonates represent the most susceptible subgroup and this was true also for glycine conjugation for which an uncertainty factor of 29 would be required to cover 99% of this subgroup. Neonatal data were not available for any other pathway analysed.

Gender differences in alcohol metabolism. Physiological responses to ethanol

A gender difference in alcohol pharmacokinetics has been suggested to explain why women are more vulnerable to ethanol's toxic effects. The results of animal experiments suggest that females exhibit higher alcohol metabolic rates than males as a result of hormonal differences. Experimental results examining gender differences in human alcohol metabolism have been inconsistent; the diversity of experimental protocols and variety of pharmacokinetic parameters reported have made comparisons of these studies very difficult. Variability in alcohol metabolic rate between individuals of the same sex is often significant, preventing an assessment of gender differences in some studies. This chapter attempts to summarize the findings of studies from the last decade that examined the role of gender and sex hormone differences on ethanol metabolism in men and women. The role of body composition, genetic factors, gastric and hepatic alcohol dehydrogenase, and gastric absorption in creating gender differences in alcohol metabolism is discussed. Suggestions are offered that may result in better cross-study comparisons and more consistent experimental results.

Toxicokinetics of organic solvents: a review of modifying factors

This article reviews, with an emphasis on human experimental data, factors known or suspected to cause changes in the toxicokinetics of organic solvents. Such changes in the toxicokinetic pattern alters the relation between external exposure and target dose and thus may explain some of the observed individual variability in susceptibility to toxic effects. Factors shown to modify the uptake, distribution, biotransformation, or excretion of solvent include physical activity (work load), body composition, age, sex, genetic polymorphism of the biotransformation, ethnicity, diet, smoking, drug treatment, and coexposure to ethanol and other solvents. A better understanding of modifying factors is needed for several reasons. First, it may help in identifying important potential confounders and eliminating negligible ones. Second, the risk assessment process may be improved if different sources of variability between external exposures and target doses can be quantitatively assessed. Third, biological exposure monitoring may be also improved for the same reason.

Ethanol metabolism, toxicity and genetic polymorphism

The relationships between the individual (and racial) differences in alcohol metabolism and toxicity, and the genetic polymorphism of alcohol dehydrogenase (ADH), aldehyde dehydrogenase (ALDH), and cytochrome P-4502E1(CYPIIE1) were reviewed. In recent studies involving DNA analysis, it was found that a deficiency of the ALDH2 isozyme (ALDH2*2) was responsible for the flushing symptoms as well as other vasomotor symptoms caused by a higher acetaldehyde level after alcohol consumption. Deficiency of ALDH2 activity has been found prevalently only among people of Mongoloid origin, and the deficiency of ALDH2 prevents them from developing alcohol dependence due to the unpleasant physical effects of the flushing symptom. It was reported that Mongoloids such as Japanese and Chinese people carry the enzymatically active (ALDH2*1) subunit and/or the inactive (ALDH2*2) one, and that a low proportion of ALDH2 deficiency (ALDH2*2 allele frequency) was found in alcoholics compared with healthy controls. It was also reported that polymorphism of ALDH2 and/or CYP2E1 may be associated with the susceptibility to alcohol-induced liver injury. Concerning blood ethanol elimination kinetics, it was reported that the c2 gene of CYP2E1 and the ALDH2*1 gene may have greater effects on ethanol and acetaldehyde elimination than the other genotypes, when the blood ethanol level is below 20 m M.

Genetic markers of alcohol abuse

In this paper, we review the current status of genetic markers for the development of alcohol abuse. Family, twin, half-sibling and adoption studies of alcoholic subjects suggest that the heritability of liability to alcoholism is at least 50%. These findings have fuelled intensive investigation in the fields of neurology, biochemistry, genetics and molecular biology aimed at the identification of markers for the risk of alcoholism. The most promising of these are discussed in detail. Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) polymorphisms, specifically the ADH3*1, ADH2*2, and ALDH2*2 genotypes appear to confer a protective effect against alcoholism, most notably in Oriental subjects. Caucasian alcohol abusers and their first-degree relatives exhibit depressed platelet monoamine oxidase activity, the degree of which is greater in Type II than Type I alcoholics. Electrophysiological characteristics of alcoholics and those at risk for developing alcoholism have also been identified, including the reduced amplitude of the event-related brain potential and, after ethanol ingestion, characteristic EEG alpha-wave activity. Lower platelet adenylate cyclase activity is seen in alcoholics compared to controls, presumably as a result of over-expression of an inhibitory G-protein. Markers related to other signal transduction pathways of the central nervous system including the serotoninergic, muscarinic and dopaminergic systems are also discussed. In this group of markers, the putative association between the inheritance of the AI allele of the D2 dopamine receptor and the susceptibility to alcoholism provides the most dramatic illustration of the challenges presently existing in this field of scientific investigation. Current limitations in the definition, diagnosis and classification of alcoholism, the confounding influences of race and gender on association studies, as well as the statistical approach of linkage studies are discussed as they relate to the endeavor to uncover valid genetic markers for the risk of alcoholism.

Investigation of the mechanism of alcohol-induced bronchial asthma

BACKGROUND

Many Japanese patients with asthma experience episodes or exacerbation of asthma after alcohol consumption. This phenomenon is not seen in Caucasians and is specific to Asians. This has been thought to be attributable to a difference in alcohol metabolism, in particular the metabolism of acetaldehyde, between Asians and Caucasians.

METHODS

An oral ethanol challenge test, a leukocyte histamine release test, and an ELISA for detection of IgE specific to acetaldehyde-human serum albumin conjugate were carried out in 42 adults with bronchial asthma and nine healthy adults.

RESULTS

Fifty-five percent of the patients with asthma responded to the ethanol challenge and showed a 20% or greater reduction in forced expiratory volume in 1 second. Blood acetaldehyde and plasma histamine levels were significantly higher in responders than in nonresponders. The leukocyte histamine release test revealed no ethanol-induced histamine release. Acetaldehyde, on the other hand, was found to induce histamine release in a volume-dependent manner. The histamine release was significantly higher in the asthma group (both responders and nonresponders) than in the healthy control group. ELISA did not detect any IgE specific to acetaldehyde-human serum albumin conjugate.

CONCLUSION

Alcohol-induced bronchial asthma seems to develop as follows. Alcohol elevates blood acetaldehyde levels, which leads to degranulation of mast cells (or basophils). The resultant release of chemical mediators, such as histamine, induces asthma.

Atypical liver alcohol dehydrogenase in the Spanish population: its relation with the development of alcoholic liver disease

The presence of atypical liver alcohol dehydrogenase (ADH) was determined in samples of liver tissue from 222 alcoholic and nonalcoholic subjects to determine its prevalence in the Spanish population, and to evaluate the possible relationship between the presence of this isoenzyme and the development of alcoholism and alcoholic liver disease. Alcoholic patients were classified into the following groups: control subjects, with normal liver pathology (group 1), patients with noncirrhotic liver disease (group 2), and patients with cirrhosis of the liver (group 3). Nonalcoholic subjects were also divided, following the same criteria, into groups 4, 5, and 6, respectively. The prevalence of atypical ADH in the population analyzed was 16.2%. Atypical ADH was present in 14.9% of alcoholics and in 17.4% of nonalcoholics (p = NS). There were no significant differences when the prevalence of atypical ADH of alcoholic and nonalcoholic patients with similar degrees of liver pathology was compared (group 1 vs. 4, group 2 vs. 5, and group 3 vs. 6). The prevalence of atypical ADH was also similar in cirrhotic patients with respect to those of noncirrhotic liver disease and control patients, either in alcoholic or nonalcoholic groups. Our findings indicate that the prevalence of atypical ADH in the Spanish population is similar to that reported for other Caucasian groups. Moreover, the presence of atypical ADH does not play a role in the development of alcoholism nor in the development of alcoholic liver disease in the population analyzed.

Why there is no gene for alcoholism

The search for and recognition of biological and genetic markers of alcoholism are discussed in the context of a heuristic model of human alcoholism as a complex, multilocus, heterogeneous disorder. Implications of this model for the interpretation of results from both linkage and association studies are presented.

Aversive reactions and alcohol use in Europeans

Two hundred subjects of European descent completed a questionnaire about alcohol use and reactions to alcohol. Eleven subjects (5.5%) reported that they always experienced unpleasant reactions after small amounts of alcohol, and these subjects reported significantly lower levels for quantity and frequency of habitual alcohol use, and fewer drinks in the preceding 7 days, than the other subjects. Reactions to alcohol, either genetic or acquired, can therefore be significant in determining alcohol use in non-Asian groups.

Changes in blood acetaldehyde levels after ethanol administration in alcoholics

Serial changes in blood ethanol (Et-OH) and acetaldehyde (Ac-CHO) levels following a single oral administration of 0.8 g/kg of Et-OH were determined in order to clarify the metabolism of Ac-CHO in alcoholic liver disease (ALD). The Et-OH metabolic rate (EMR) in alcoholics either with or without liver disease was significantly higher than the rate in nonalcoholics. Peak values of blood Ac-CHO levels and the Ac-CHO/EMR ratios in ALD were significantly higher than those in subjects with nonALD or alcoholics and nonalcoholics without liver disease. In the type I aldehyde dehydrogenase isozyme deficient cases (unusual type), blood Ac-CHO levels and Ac-CHO/EMR ratios were very high and the levels remain at a plateau until 90 minutes after Et-OH administration and then decreased relatively quickly. Changes in blood Ac-CHO levels and Ac-CHO/EMR ratios in ALD were similar to those in cases of the unusual type. These results indicate that Ac-CHO metabolism in ALD is decreased relative to its production and that this decrease might be due to increased production of Ac-CHO in the nonalcohol dehydrogenase pathway located in the microsomes, in which degradation of Ac-CHO was slow.

Comparative study on ethanol elimination and blood acetaldehyde between alcoholics and control subjects

Factors influencing ethanol elimination rate and blood acetaldehyde concentration with regard to age, blood ethanol concentration, and degrees of alcoholic liver disorder were studied in alcoholic patients vis-à-vis healthy subjects. Ninety-four male alcoholic patients were divided into five groups according to age and into three groups according to blood ethanol concentration which ranged between 4.21 and 0.29 mg/ml. It was noted that as age increased, blood ethanol concentration decreased. Groups A, B, and C consisted of subjects whose ethanol levels were more than 2.5, between 1.0 and 2.5, and less than 1.0 mg/ml, respectively. Average values of ethanol elimination rate in Groups A, B, and C were 0.26, 0.23, and 0.18 mg/ml/hr, respectively. The rate increased as blood ethanol concentration elevated. The rate in Group B was significantly higher than that in the healthy control subjects who had blood ethanol levels between 1.0 and 2.5 mg/ml. The rate of ethanol elimination was independent of liver disorder judged by liver function test values. Blood acetaldehyde concentrations in the patients were less than 1.48 micrograms/ml, with an average value of 0.58 microgram/ml, and were significantly correlated with blood ethanol levels in both alcoholics and healthy subjects.