Ethnic differences in gastric sigma-alcohol dehydrogenase activity and ethanol first-pass metabolism

A physiologically-based digital twin for alcohol consumption-predicting real-life drinking responses and long-term plasma PEth

Alcohol consumption is associated with a wide variety of preventable health complications and is a major risk factor for all-cause mortality in the age group 15-47 years. To reduce dangerous drinking behavior, eHealth applications have shown promise. A particularly interesting potential lies in the combination of eHealth apps with mathematical models. However, existing mathematical models do not consider real-life situations, such as combined intake of meals and beverages, and do not connect drinking to clinical markers, such as phosphatidylethanol (PEth). Herein, we present such a model which can simulate real-life situations and connect drinking to long-term markers. The new model can accurately describe both estimation data according to a χ2 -test (187.0 < Tχ2 = 226.4) and independent validation data (70.8 < Tχ2 = 93.5). The model can also be personalized using anthropometric data from a specific individual and can thus be used as a physiologically-based digital twin. This twin is also able to connect short-term consumption of alcohol to the long-term dynamics of PEth levels in the blood, a clinical biomarker of alcohol consumption. Here we illustrate how connecting short-term consumption to long-term markers allows for a new way to determine patient alcohol consumption from measured PEth levels. An additional use case of the twin could include the combined evaluation of patient-reported AUDIT forms and measured PEth levels. Finally, we integrated the new model into an eHealth application, which could help guide individual users or clinicians to help reduce dangerous drinking.

The effect of alcohol dose on the development of hypertension in Asian and Western men: systematic review and meta-analysis

BACKGROUND/AIMS

There are inconsistencies in the effects of low to moderate dose alcohol consumption on the development of hypertension in adult men. We hypothesized that a region-specific effect might participate in this heterogeneity.

METHODS

We conducted a systematic review and meta-analysis to evaluate the effect of alcohol dose on hypertension incidence using contemporary data through December 2017. Subjects were categorized according to their level of alcohol consumption as non-drinkers (reference) and low- (0.01 to 20.0 g/day), moderate- (20.1 to 40.0 g/day), moderate- to high- (40.1 to 60.0 g/day), and high-dose (> 60.0 g/day) drinkers. We defined hypertension as a blood pressure ≥ 140/90 mmHg and/or the use of anti-hypertensive drugs.

RESULTS

In total, 11 articles (seven Asian and four Western) were selected for our analysis. Among Asian men, a significantly elevated risk was observed even in the low alcohol dose group in comparison with the group with no alcohol consumption, and the risk increased in a dose-dependent manner (pooled relative risks [95% confidence intervals (CI)]: 1.25 [1.13 to 1.38], 1.48 [1.27 to 1.72], 1.75 [1.43 to 2.15], and 1.78 [1.51 to 2.09]). Among Western men, a similar dose-response relationship was noted in general (p for subgroup difference > 0.1), but a significantly elevated risk was evident only in the high-dose group (pooled relative risks [95% CI]: 1.22 [0.85 to 1.74], 1.57 [0.90 to 2.75], 1.47 [0.44 to 4.91], and 1.49 [1.02 to 2.18]).

CONCLUSION

Even low doses of alcohol can lead to the development of hypertension, particularly in Asian men. Our findings could serve as additional evidence for developing an appropriate preventive strategy in each region.

Alcohol Metabolizing Enzymes, Microsomal Ethanol Oxidizing System, Cytochrome P450 2E1, Catalase, and Aldehyde Dehydrogenase in Alcohol-Associated Liver Disease

Once ingested, most of the alcohol is metabolized in the liver by alcohol dehydrogenase to acetaldehyde. Two additional pathways of acetaldehyde generation are by microsomal ethanol oxidizing system (cytochrome P450 2E1) and catalase. Acetaldehyde can form adducts which can interfere with cellular function, leading to alcohol-induced liver injury. The variants of alcohol metabolizing genes encode enzymes with varied kinetic properties and result in the different rate of alcohol elimination and acetaldehyde generation. Allelic variants of these genes with higher enzymatic activity are believed to be able to modify susceptibility to alcohol-induced liver injury; however, the human studies on the association of these variants and alcohol-associated liver disease are inconclusive. In addition to acetaldehyde, the shift in the redox state during alcohol elimination may also link to other pathways resulting in activation of downstream signaling leading to liver injury.

Alcohol Dehydrogenases, Aldehyde Dehydrogenases, and Alcohol Use Disorders: A Critical Review

Alcohol use disorders (AUDs) are complex traits, meaning that variations in many genes contribute to the risk, as does the environment. Although the total genetic contribution to risk is substantial, most individual variations make only very small contributions. By far the strongest contributors are functional variations in 2 genes involved in alcohol (ethanol [EtOH]) metabolism. A functional variant in alcohol dehydrogenase 1B (ADH1B) is protective in people of European and Asian descent, and a different functional variant in the same gene is protective in those of African descent. A strongly protective variant in aldehyde dehydrogenase 2 (ALDH2) is essentially only found in Asians. This highlights the need to study a wide range of populations. The likely mechanism of protection against heavy drinking and AUDs in both cases is alteration in the rate of metabolism of EtOH that at least transiently elevates acetaldehyde. Other ADH and ALDH variants, including functional variations in ADH1C, have also been implicated in affecting drinking behavior and risk for alcoholism. The pattern of linkage disequilibrium in the ADH region and the differences among populations complicate analyses, particularly of regulatory variants. This critical review focuses upon the ADH and ALDH genes as they affect AUDs.

Activity of alcohol dehydrogenase isoenzymes and aldehyde dehydrogenase in sera of patients with hepatitis C

INTRODUCTION

The changes of enzyme activity in the hepatocytes in the course of different liver diseases are reflected by increase of the corresponding enzyme activity in the plasma. For example, the activities of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) correlate with the severity of the condition during cirrhosis. In this study we measured the activity of ADH isoenzymes and ALDH in the sera of patients with hepatitis C.

MATERIAL AND METHODS

Serum samples were taken from 60 patients suffering from viral hepatitis C and from 66 control subjects. Total ADH activity and class III and IV isoenzymes were measured by the photometric method and ALDH activity, ADH I and II by the fluorometric method.

RESULTS

The ADH activity was significantly higher in patients with hepatitis C than in healthy (p < 0.001). The total activity of ADH was 1284 mU/l in patients, and 745 mU/l (controls). The activity of isoenzymes classes ADH I and ADH II in the hepatitis C group increased respectively 55% (4.24 vs. 1.88 mU/l; p < 0.001) and 47% (26.63 vs. 14.11 mU/l; p < 0.001) in the comparison to the control. There was significant increase in the activity of ADH I isoenzyme (4.96 vs. 3.81 mU/l; p < 0.001) and ADH total (1833 vs. 1105 mU/l; p < 0.001) in patients with high viral load in comparison to patients with low viral load.

CONCLUSIONS

The activity of class I and II ADH isoenzymes in the sera of patients with hepatitis C is increased, and it seems to be caused by the release of these isoenzymes from damaged liver cells.

The alterations in alcohol dehydrogenase and aldehyde dehydrogenase activities in the sera of patients with renal cell carcinoma

PURPOSE

In a previous study we showed that the total activity of alcohol dehydrogenase (ADH) and its isoenzyme class I was significantly higher in renal cancer (RCC) cells compared to normal kidney. The aim of this study was to compare the activities of ADH isoenzymes and aldehyde dehydrogenase (ALDH) in the sera of patients with different stages of RCC and healthy subjects.

MATERIALS AND METHODS

Serum samples were taken from 54 patients with clear cell RCC (17 patients in stage II, 22 in stage III and 15 in stage IV) and 52 healthy patients. Class III, IV of ADH and the total ADH activity was measured by the photometric method. For the measurement of ADH class I, II and the total ALDH activity we employed the fluorometric method.

RESULTS

The total activity of ADH and its isoenzyme class I were significantly higher in the sera of patients with every stage of RCC compared to healthy subjects. The analysis of ALDH activity did not indicate significant differences between tested groups.

CONCLUSIONS

The increased activity of total ADH and its isoenzyme class I in the sera of patients with RCC, seems to be caused by isoenzymes being released from cancerous cells and may be useful for diagnostics of renal cancer.

Morphological and biochemical effects of weekend alcohol consumption in rats: Role of concentration and gender

AIM

To examine the association between weekend alcohol consumption and the biochemical and histological alterations at two different concentrations of alcohol in both genders in rats.

METHODS

Wistar rats weighing 170-200 g were divided into groups as follows: (1) Control groups; and (2) weekend alcohol-consumption group: 2 d/weekly per 12 wk, at two different concentrations: (1) Group of males or females with a consumption of a solution of alcohol at 40%; and (2) group of males or females with a consumption of a solution of alcohol at 5%. At the end of the experiment, serum and liver samples were obtained. The following enzymes and metabolites were determined in serum: Alanine Aminotransferase (ALT), Aspartate Aminotransferase (AST), Lactate Dehydrogenase, and Gamma-Glutamyltransferase, and glucose, triglycerides, cholesterol, bilirubin, and albumin. Liver samples from each group were employed to analyze morphological abnormalities by light microscopy.

RESULTS

In all of the weekend alcohol-consumption groups, AST activity presented a significant, 10-fold rise. Regarding ALT activity, the groups with weekend alcohol consumption presented a significant increase that was six times greater. Bilirubin levels increased significantly in both groups of females. We observed a significant increase in the parameters of fatty change and inflammation due to weekend alcohol consumption. Only the group of females that consumed alcohol at 40% presented slight hepatocellular disorganization

CONCLUSION

The results obtained herein provide solid evidence that weekend alcohol consumption gives rise to liver damage, demonstrated by biochemical and histological alterations, first manifested acutely, and prolonged weekend alcohol consumption can cause greater, irreversible damage.

The Activity of Class I-IV Alcohol Dehydrogenase Isoenzymes and Aldehyde Dehydrogenase in Bladder Cancer Cells

OBJECTIVES

The aim of this study was to determine the differences in the activity of Alcohol Dehydrogenase (ADH) isoenzymes and Aldehyde Dehydrogenase (ALDH) in normal and cancerous bladder cells.

METHODS

Class III, IV of ADH and total ADH activity were measured by the photometric method and class I, II ADH and ALDH activity by the fluorometric method.

RESULTS

Significantly higher total activity of ADH was found in both, low-grade and high-grade bladder cancer, in comparison to healthy tissues.

CONCLUSION

The increased activity of total ADH in bladder cancer cells may be the cause of metabolic disorders in cancer cells, which may intensify carcinogenesis.

The diagnostic value of alcohol dehydrogenase (ADH) isoenzymes and aldehyde dehydrogenase (ALDH) measurement in the sera of patients with brain tumor

INTRODUCTION

Alcohol dehydrogenase (ADH) isoenzymes and aldehyde dehydrogenase (ALDH) exist in the brain. Alcohol dehydrogenase and ALDH are also present in brain tumor cells. Moreover, the activity of class I isoenzymes was significantly higher in cancer than healthy brain cells. The activity of these enzymes in tumor tissue is reflected in the serum and could thus be helpful for diagnostics of brain neoplasms. The aim of this study was to investigate the potential role of ADH and ALDH as markers for brain tumors.

MATERIAL AND METHODS

Serum samples were taken for routine biochemical investigation from 115 patients suffering from brain tumors (65 glioblastomas, 50 meningiomas). For the measurement of the activity of class I and II ADH isoenzymes and ALDH activity, fluorometric methods were used. The total ADH activity and activity of class III and IV isoenzymes were measured by the photometric method.

RESULTS

There was a significant increase in the activity of ADH I isoenzyme and ADH total in the sera of brain tumor patients compared to the controls. The diagnostic sensitivity for ADH I was 78%, specificity 85%, and positive and negative predictive values were 86% and 76% respectively. The sensitivity and specificity of ADH I increased with the stage of the carcinoma. Area under receiver-operating characteristic curve for ADH I was 0.71.

CONCLUSIONS

The results suggest a potential role for ADH I as a marker for brain tumor.

The diagnostic significance of serum alcohol dehydrogenase isoenzymes and aldehyde dehydrogenase activity in renal cell cancer patients

OBJECTIVES

In previous experiments, we have found an increased level of class I ADH and total ADH activity in RCC tissues. Changes in cancer cells may be reflected by ADH activity in the serum and could thus be helpful for diagnostics of renal cancer. The aim of this study was to investigate a potential role of ADH and ALDH as tumor markers for RCC.

MATERIAL AND METHODS

Serum samples were taken from 59 patients with RCC and 52 healthy subjects. Class III and IV of ADH and total ADH activity was measured by the photometric method. For measurement of class I and II ADH and ALDH activity, we employed the fluorometric method.

RESULTS

The total activity of ADH and ADH I was significantly higher in the serum of patients with every stage of RCC compared to healthy subjects. The diagnostics criteria was higher for ADH I than for total ADH activity. The diagnostic sensitivity for ADH I was 73.36%, specificity 85.61%, predictive values of positive and negative results were 79.12 and 75.03% respectively. Area under ROC curve for ADH I was 0.748 and for total ADH 0.689.

CONCLUSION

The results suggest a potential role of ADH I as a marker for RCC.

The activity of class I, II, III and IV alcohol dehydrogenase isoenzymes and aldehyde dehydrogenase in renal cell carcinoma

OBJECTIVES

Ethanol has been considered as a lifestyle risk factor for cancer in humans. While some studies have indicated that alcohol intake has a preventive effect for renal cell cancer, others have not. The metabolism of alcohol in cancer cells may be in many ways different than in healthy tissue and its disturbances could be associated with carcinogenesis. The aim of this study was to compare the metabolism of renal cell cancer cells and normal renal cells by measurement of ADH isoenzymes and ALDH activities in these tissues.

MATERIAL AND METHODS

The study material consisted of 43 cancerous renal tissues (14 patients in stage II, 19 in stage III and 10 in stage IV). Class III and IV ADH and total ADH activities were measured by the photometric method and class I and II ADH and ALDH activities by the fluorometric method with class-specific fluorogenic substrates.

RESULTS

The activity of the class I ADH isoenzyme and the total ADH was significantly higher in every stage of renal cell cancer as compared to healthy tissues. Analysis of ALDH activity did not show statistically significant differences between cancer and healthy cells.

CONCLUSION

The increased activity of total ADH in renal cell cancer, especially the class I isoenzyme and normal activity of ALDH, may be the factor intensifying carcinogenesis because of increasing the ability to highly carcinogenic acetaldehyde formation and causing disorders in metabolism of many biologically important substances.

The alcohol dehydrogenase isoenzyme alcohol dehydrogenase IV as a candidate marker of Helicobacter pylori infection

INTRODUCTION

Helicobacter pylori infection is associated with decreased alcohol dehydrogenase (ADH) activity in the gastric mucosa. The decrease in gastric ADH activity depends on the severity of inflammation and mucosal injury. This damage can be a reason of the release of enzyme from gastric mucosa and leads to the increase of the ADH activity in the sera of patients with H. pylori infection.

MATERIAL AND METHODS

Serum samples were taken from 140 patients with H. pylori infection. Total ADH activity was measured by photometric method with p-nitrosodimethylaniline as a substrate and ALDH activity by the fluorometric method with 6-methoxy-2-naphtaldehyde. For the measurement of the activity of class I and II isoenzymes we employed the fluorometric methods, with class-specific fluorogenic substrates. The activity of class III ADH was measured by the photometric method with n-octanol and class IV with m-nitrobenzaldehyde as a substrate.

RESULTS

The activity of ADH IV in the serum of patients with H. pylori infection increased about 42% (7.86 mU/l) in the comparison to the control level (4.52 mU/l). Total activity of ADH was 1105 mU/l in patients group and 682 mU/l in control. The diagnostic sensitivity for ADH IV was 88%, specificity 90%, positive and negative predictive values were 91% and 84% respectively. Area under ROC curve for ADH IV was 0.84.

CONCLUSIONS

Helicobacter pylori infection of gastric mucosa is reflected in the serum by significant increase of class IV and total ADH activity. The results suggest a potential role for ADH IV as a marker of H. pylori infection.

The activity of alcohol dehydrogenase (ADH) isoenzymes and aldehyde dehydrogenase (ALDH) in the sera of patients with brain cancer

Human brain tissue contains various alcohol dehydrogenase (ADH) isoenzymes and possess also aldehyde dehydrogenase (ALDH) activity. In our last experiments we have shown that ADH and ALDH are present also in the brain tumour cells. Moreover the activities of total ADH and class I isoenzymes were significantly higher in cancer tissue than healthy cells. It can suggests that these changes may be reflected by enzyme activity in the serum of patients with brain cancer. Serum samples were taken for routine biochemical investigation from 62 patients suffering from brain cancer (36 glioblastoma, 26 meningioma). For the measurement of the activity of class I and II ADH isoenzymes and ALDH activity, the fluorometric methods were used. The total ADH activity and activity of class III and IV isoenzymes were measured by the photometric method. A statistically significant increase of class I alcohol dehydrogenase isoenzymes was found in the sera of patients with brain cancer. The median activity of this class isoenzyme in the patients group increased about 24 % in the comparison to the control level. The total alcohol dehydrogenase activity was also significantly higher (26 %) among patients with brain tumour than healthy ones. The activities of other tested ADH isoenzymes and total ALDH were unchanged. The increase of the activity of total ADH and class I alcohol dehydrogenase isoenzyme in the sera of patients with brain cancer seems to be caused by the release of this isoenzyme from tumour's cells.

The activity of class I, II, III and IV alcohol dehydrogenase isoenzymes and aldehyde dehydrogenase in ovarian cancer and ovarian cysts

PURPOSE

The metabolism of cancerous cells is in many ways different than in healthy cells. In ovarian cancer, cells exhibit activity of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), which participate in metabolism of many biological substances. The aim of this study was to compare the metabolism of ovarian cancer cells, ovarian cysts and normal ovarian cells by measurement of ADH isoenzymes and ALDH activities.

MATERIAL AND METHODS

The study material consisted of 36 cancerous ovarian tissues. Class III, IV of ADH and total ADH activity was measured by the photometric method and class I, II ADH and ALDH activity by the fluorometric method with class-specific fluorogenic substrates.

RESULTS

The activity of the class I ADH isoenzyme and the total ADH was significantly higher in ovarian cancer as compared to ovarian cysts and healthy tissues but there are no significant differences between ovarian cysts and healthy cells. The other classes of ADH tested, did not show significant differences between activity of cancerous cells and healthy ovary.

CONCLUSION

The increased activity of total ADH in ovarian cancer, especially the class I isoenzyme and normal activity of ALDH, may be the factor for the disturbances in important biological substances metabolism and could increase the concentration of highly carcinogenic acetaldehyde.

Alcohol: Pharmacology and Disposition

Alcohol is the most common drug detected in forensic cases, is often associated with increased aggression and other disinhibitory behaviors in criminal matters, and frequently contributes to the cause of death in medical examiner cases. Significant adverse effects of alcohol generally manifest at blood alcohol concentrations above 100 mg/dL. In postmortem cases, a number of factors can affect the accuracy of the blood measurement, including site of sampling and putrefactive formation. This paper provides an overview of the pharmacology, pharmacokinetics, and interpretation of alcohol and its concentrations in key specimens, with application to forensic medical cases.

Ethanol metabolism and its effects on the intestinal epithelial barrier

Ethanol is widely consumed and is associated with an increasing global health burden. Several reviews have addressed the effects of ethanol and its oxidative metabolite, acetaldehyde, on the gastrointestinal (GI) tract, focusing on carcinogenic effects or alcoholic liver disease. However, both the oxidative and the nonoxidative metabolites of ethanol can affect the epithelial barrier of the small and large intestines, thereby contributing to GI and liver diseases. This review outlines the possible mechanisms of ethanol metabolism as well as the effects of ethanol and its metabolites on the intestinal barrier. Limited studies in humans and supporting in vitro data have indicated that ethanol as well as mainly acetaldehyde can increase small intestinal permeability. Limited evidence also points to increased colon permeability following exposure to ethanol or acetaldehyde. In vitro studies have provided several mechanisms for disruption of the epithelial barrier, including activation of different cell-signaling pathways, oxidative stress, and remodeling of the cytoskeleton. Modulation via intestinal microbiota, however, should also be considered. In conclusion, ethanol and its metabolites may act additively or even synergistically in vivo. Therefore, in vivo studies investigating the effects of ethanol and its byproducts on permeability of the small and large intestines are warranted.

The activity of class I, II, III and IV of alcohol dehydrogenase (ADH) isoenzymes and aldehyde dehydrogenase (ALDH) in brain cancer

The brain being highly sensitive to the action of alcohol is potentially susceptible to its carcinogenic effects. Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) are the main enzymes involved in ethanol metabolism, which leads to the generation of carcinogenic acetaldehyde. Human brain tissue contains various ADH isoenzymes and possess also ALDH activity. The purpose of this study was to compare the capacity for ethanol metabolism measured by ADH isoenzymes and ALDH activity in cancer tissues and healthy brain cells. The samples were taken from 62 brain cancer patients (36 glioblastoma, 26 meningioma). For the measurement of the activity of class I and II ADH isoenzymes and ALDH activity, the fluorometric methods were used. The total ADH activity and activity of class III and IV isoenzymes were measured by the photometric method. The total activity of ADH, and activity of class I ADH were significantly higher in cancer cells than in healthy tissues. The other tested classes of ADH and ALDH did not show statistically significant differences of activity in cancer and in normal cells. Analysis of the enzymes activity did not show significant differences depending on the location of the tumor. The differences in the activity of total alcohol dehydrogenase, and class I isoenzyme between cancer tissues and healthy brain cells might be a factor for metabolic changes and disturbances in low mature cancer cells and additionally might be a reason for higher level of acetaldehyde which can intensify the carcinogenesis.

Population pharmacokinetics and pharmacogenetics of alcohol in Chinese and Indians in Singapore

WHAT IS KNOWN AND OBJECTIVE

  Interindividual variability in alcohol pharmacokinetics is influenced by a number of factors, including polymorphisms in genes mediating alcohol pharmacology, ethnicity, sex and body size. Several studies have evaluated the population pharmacokinetics of alcohol from breath alcohol measures. None of these studies, however, have evaluated ethnicity and alcohol-metabolizing enzyme genotypes as covariates in their population pharmacokinetic modelling. We aimed to develop a population pharmacokinetic model using clinical and genetic factors and to identify covariates that influenced interindividual variability in alcohol clearance and volume of distribution.

METHODS

  Hundred and eighty healthy subjects (90 Chinese and 90 Indians; 45 males and 45 females from each ethnic group) ingested a vodka-orange juice mixture to simulate social drinking. Subjects were genotyped for the ADH1B (Arg48His), ALDH2 (Glu504Lys) and CYP2E1 (c.-1293G>C and c.-1053C>T) polymorphisms. A base pharmacokinetic model was developed using the nonmem software (NONMEM Project Group, University of California, San Francisco, San Francisco, CA, USA) to determine the alcohol clearance and volume of distribution. The model was extended to include covariates that influenced the between-subject variability.

RESULTS AND DISCUSSION

  Body weight and sex significantly influenced absorption rate and volume of distribution of alcohol. Body weight and ADH1B Arg48His polymorphism significantly influenced alcohol clearance. The Michaelis-Menten elimination rate (Vmax ) was decreased by 10% in homozygous ADH1B*1/*1 subjects. Ethnicity was not determined to be a significant covariate in the final population pharmacokinetic model.

WHAT IS NEW AND CONCLUSION

  Gender and body weight were covariates that contributed most to explaining the observed interindividual alcohol pharmacokinetic variability. Of the four SNPs examined in this study, only ADH1B Arg48His polymorphism had a significant, though modest, effect on the pharmacokinetics of alcohol.

Inhibition of human alcohol and aldehyde dehydrogenases by cimetidine and assessment of its effects on ethanol metabolism

Previous studies have reported that cimetidine, an H2-receptor antagonist used to treat gastric and duodenal ulcers, can inhibit alcohol dehydrogenases (ADHs) and ethanol metabolism. Human alcohol dehydrogenases and aldehyde dehydrogenases (ALDHs), the principal enzymes responsible for metabolism of ethanol, are complex enzyme families that exhibit functional polymorphisms among ethnic groups and distinct tissue distributions. We investigated the inhibition by cimetidine of alcohol oxidation by recombinant human ADH1A, ADH1B1, ADH1B2, ADH1B3, ADH1C1, ADH1C2, ADH2, and ADH4, and aldehyde oxidation by ALDH1A1 and ALDH2 at pH 7.5 and a cytosolic NAD(+) concentration. Cimetidine acted as competitive or noncompetitive inhibitors for the ADH and ALDH isozymes/allozymes with near mM inhibition constants. The metabolic interactions between cimetidine and ethanol/acetaldehyde were assessed by computer simulation using the inhibition equations and the determined kinetic constants. At therapeutic drug levels (0.015 mM) and physiologically relevant concentrations of ethanol (10 mM) and acetaldehyde (10 μM) in target tissues, cimetidine could weakly inhibit (<5%) the activities of ADH1B2 and ADH1B3 in liver, ADH2 in liver and small intestine, ADH4 in stomach, and ALDH1A1 in the three tissues, but not significantly affect ADH1A, ADH1B1, ADH1C1/2, or ALDH2. At higher drug levels, which may accumulate in cells (0.2 mM), the activities of the weakly-inhibited enzymes may be decreased more significantly. The quantitative effects of cimetidine on metabolism of ethanol and other physiological substrates of ADHs need further investigation.

The natural history of class I primate alcohol dehydrogenases includes gene duplication, gene loss, and gene conversion

BACKGROUND

Gene duplication is a source of molecular innovation throughout evolution. However, even with massive amounts of genome sequence data, correlating gene duplication with speciation and other events in natural history can be difficult. This is especially true in its most interesting cases, where rapid and multiple duplications are likely to reflect adaptation to rapidly changing environments and life styles. This may be so for Class I of alcohol dehydrogenases (ADH1s), where multiple duplications occurred in primate lineages in Old and New World monkeys (OWMs and NWMs) and hominoids.

METHODOLOGY/PRINCIPAL FINDINGS

To build a preferred model for the natural history of ADH1s, we determined the sequences of nine new ADH1 genes, finding for the first time multiple paralogs in various prosimians (lemurs, strepsirhines). Database mining then identified novel ADH1 paralogs in both macaque (an OWM) and marmoset (a NWM). These were used with the previously identified human paralogs to resolve controversies relating to dates of duplication and gene conversion in the ADH1 family. Central to these controversies are differences in the topologies of trees generated from exonic (coding) sequences and intronic sequences.

CONCLUSIONS/SIGNIFICANCE

We provide evidence that gene conversions are the primary source of difference, using molecular clock dating of duplications and analyses of microinsertions and deletions (micro-indels). The tree topology inferred from intron sequences appear to more correctly represent the natural history of ADH1s, with the ADH1 paralogs in platyrrhines (NWMs) and catarrhines (OWMs and hominoids) having arisen by duplications shortly predating the divergence of OWMs and NWMs. We also conclude that paralogs in lemurs arose independently. Finally, we identify errors in database interpretation as the source of controversies concerning gene conversion. These analyses provide a model for the natural history of ADH1s that posits four ADH1 paralogs in the ancestor of Catarrhine and Platyrrhine primates, followed by the loss of an ADH1 paralog in the human lineage.

Alcohol-drinking patterns and metabolic syndrome risk: the 2007 Korean National Health and Nutrition Examination Survey

Alcohol consumption has been known to be related to the prevalence of metabolic syndrome (MS). Although some studies have revealed that mild to moderate alcohol consumption reduces the risk of MS, most of these studies have focused the effect of alcohol consumption amount on MS. We examined the association between alcohol-drinking patterns and MS by using the alcohol use disorders identification test (AUDIT) questionnaire to study 1,768 alcohol drinkers (847 men, 921 women) aged 20-75 years from Korean National Health and Nutrition Examination Survey in 2007. When compared with the subjects in the reference group (AUDIT score ≤ 7), the odds ratios (ORs, 95% confidence intervals [CIs]) for MS of subjects in the highest group (AUDIT score ≥ 16) were 3.92 (2.40-6.22) in men and 2.27 (0.87-5.89) in women after adjusting for confounding variables. Among the items of the AUDIT score, several alcohol-drinking patterns, including "drinking frequency," "usual drinking quantity," "frequency of high-risk drinking," "frequency of inability to stop drinking," "frequency of feeling guilty after drinking," and "frequency of inability to remember after drinking" were strongly associated with the prevalence of MS in men. In women, there were significant relationships between MS and "usual drinking quantity," "frequency of feeling guilty after drinking," and "frequency of inability to stop drinking." In summary, AUDIT score was strongly associated with MS in Korean adults, particularly in men. Accordingly, in addition to the amount of daily alcohol consumption, alcohol-drinking patterns should be addressed in the prevention and treatment of MS.

The activity of class I, II, III and IV alcohol dehydrogenase isoenzymes and aldehyde dehydrogenase in cervical cancer

OBJECTIVE

The aim of this study was to compare the metabolism of cervical cancer cells and normal cervical cells by measurement of ADH isoenzymes and ALDH activities.

METHODS

The study material consisted of 40 cancerous cervical tissues. Class III, IV of ADH and total ADH activity was measured by the photometric method and class I, II ADH and ALDH activity by the fluorometric method with class-specific fluorogenic substrates.

RESULTS

The activity of the class I ADH isoenzyme and the total ADH were significantly higher in cervical cancer as compared to healthy tissues. Class I of ADH and total ADH activity are significantly higher in every stage of cancer as compared to the control. There are no significant differences between planoepitheliale and adenocarcinoma.

CONCLUSION

The increased activity of total ADH in cervical cancer may be the cause of some metabolic disorders in cancer cells, which may intensify carcinogenesis in this organ.

The activity of class I, II, III, and IV alcohol dehydrogenase isoenzymes and aldehyde dehydrogenase in endometrial cancer

OBJECTIVE

The metabolism of cancerous cells is in many ways different than in healthy cells. In endometrial cancer, cells exhibit activity of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), which participate in the metabolism of many biological substances. The aim of this study was to compare the metabolism of endometrial cancer cells and normal endometrial cells by measurement of ADH isoenzymes and ALDH activities in these tissues.

METHODS

The study material consists of cancerous endometrial tissues obtained from 34 patients. Total ADH activity was measured using the photometric method and ALDH activity using the fluorometric method. For the measurement of class I and II ADH isoenzyme activity, we employed the fluorometric method, with class-specific fluorogenic substrates. The activity of class III and IV ADH was measured using the photometric method.

RESULTS

The activity of the class I ADH isoenzyme was significantly higher in the endometrial cancer tissues when compared with normal endometrial tissues. The other classes of ADH tested did not show significant differences between activity of cancerous cells and healthy endometrium. The activity of total ADH was also significantly higher in endometrial cancer.

CONCLUSION

The increased activity of total ADH in endometrial cancer, especially the class I isoenzyme and normal activity of ALDH, may be the cause of disorders in metabolic pathways that use these isoenzymes and could increase the concentration of acetaldehyde, which is cancerogenic substance.

The diagnostic value of alcohol dehydrogenase (ADH) isoenzymes and aldehyde dehydrogenase (ALDH) measurement in the sera of colorectal cancer patients

BACKGROUND

The activity of total alcohol dehydrogenase (ADH) and class I isoenzymes is significantly higher in colorectal cancer tissue than in healthy mucosa. The activity of these enzymes in cancer cells is probably reflected in the sera and could thus be helpful for diagnosing colorectal cancer.

AIM

The aim of this study was to investigate a potential role of ADH and aldehyde dehydrogenase (ALDH) as tumor markers for colorectal cancer. We defined diagnostic sensitivity, specificity, positive and negative predictive values, and receiver-operating characteristics (ROC) curve for tested enzymes.

METHODS

Serum samples were taken from 182 patients with colorectal cancer before treatment and from 160 control subjects. Total ADH activity and class III and IV isoenzymes were measured by photometric, but ALDH activity and ADH I and II by the fluorometric method, with class-specific fluorogenic substrates.

RESULTS

There was significant increase in the activity of ADH I isoenzyme and ADH total in the sera of colorectal cancer patients compared to the control. The diagnostic sensitivity for ADH I was 76%, specificity 82%, AND positive and negative predictive values were 85 and 74%, respectively. The sensitivity and specificity of ADH I increased with the stage of the carcinoma. The area under ROC curve for ADH I was 0.72.

CONCLUSION

The results suggest a potential role for ADH I as marker for colorectal cancer.

Relationship between alcohol consumption and serum adiponectin levels: the Takahata study--a cross-sectional study of a healthy Japanese population

CONTEXT

The relationship between alcohol consumption and serum adiponectin levels has not been fully explored in an Asian population.

OBJECTIVE

Our goal was to determine whether alcohol consumption is associated with a change in adiponectin levels in a healthy Japanese population.

DESIGN

This was a cross-sectional study.

SETTING

Subjects were recruited from participants in a health check-up program.

PARTICIPANTS

This study included 2932 subjects (1306 men and 1626 women).

MAIN OUTCOME MEASURES

The effects of total weekly or daily volume of ethanol intake on serum adiponectin levels were evaluated. In addition, the correlation of clinical traits with serum adiponectin levels was examined. A multivariate regression model was used to control for possible confounding factors.

RESULTS

Alcohol consumption was weakly correlated with decreased serum adiponectin levels in men [Spearman's ordered correlation coefficient (rs=-0.141; P<0.001]; an even weaker correlation was seen in women (rs=-0.055; P=0.025). Multivariate analysis demonstrated that alcohol consumption was independently associated with hypoadiponectinemia.

CONCLUSION

In contrast to reports from the United States and Europe among White and Black subjects, our study demonstrated an inverse association between alcohol intake and serum adiponectin levels in Asian subjects, suggesting ethnic differences in the effects of alcohol consumption on serum adiponectin levels.

The diagnostic value of alcohol dehydrogenase (ADH) isoenzymes and aldehyde dehydrogenase (ALDH) measurement in the sera of gastric cancer patients

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) are present in gastric cancer cells (GC). Moreover, the activity of total ADH and class IV isoenzymes is significantly higher in cancer tissue than in healthy mucosa. The activity of these enzymes in cancer cells is probably reflected in the sera and could thus be helpful for diagnostics of gastric cancer. The aim of this study was to investigate a potential role of ADH and ALDH as tumor markers for gastric cancer. We defined diagnostic sensitivity, specificity, predictive value for positive and negative results, and receiver-operating characteristics (ROC) curve for tested enzymes. Serum samples were taken from 168 patients with gastric cancer before treatment and from 168 control subjects. Total ADH activity and class III and IV isoenzymes were measured by photometric but ALDH activity and ADH I and II by the fluorometric method, with class-specific fluorogenic substrates. There was significant increase in the activity of ADH IV isoenzyme and ADH total in the sera of gastric cancer patients compared to the control. The diagnostic sensitivity for ADH IV was 73%, specificity 79%, positive and negative predictive values were 81 and 72% respectively. Area under ROC curve for ADH IV was 0.67. The results suggest a potential role for ADH IV as marker of gastric cancer.

Association between alcohol intake amount and prevalence of metabolic syndrome in Korean rural male population

Moderate alcohol consumption is known to be associated with a reduced risk of cardiovascular disease and mortality. However, few studies reported that long-term alcohol drinking may increase the prevalence of central obesity, and cardiovascular disease. We examined the association between metabolic syndrome, nutritional factors and alcohol intake amount in Korean male rural population. We performed a cross-sectional analysis on data from Korean Rural Genomic Cohort (KRGC) study. We used multiple logistic regression analysis to estimate the adjusted odds ratio of metabolic syndrome according to alcohol intake amount categories (never, 0-16 g/day, 16-40 g/day, and >40 g/day). The age adjusted odds ratio for the prevalence of metabolic syndrome was significantly increased in the quartile with the highest alcohol consumption compared to the non-alcohol drinking group (1.33; C.I., 1.11-1.59). These results were similar in the high energy intake group, but not in the low energy intake group. Waist circumference, blood pressure, and serum triglyceride levels were significantly higher in the quartile with the highest alcohol consumption compared to the non-alcohol drinking group. These results suggest that large alcohol consumption is associated with metabolic syndrome and may be a modifiable risk factor of metabolic syndrome especially in subjects with high calorie intake.

The activity of class I, II, III, and IV alcohol dehydrogenase (ADH) isoenzymes and aldehyde dehydrogenase (ALDH) in esophageal cancer

BACKGROUND/AIMS

Ethanol consumption is associated with an increased risk of esophageal cancer. The carcinogenic compound is acetaldehyde, the product of ethanol metabolism. Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) are the main enzymes involved in ethanol metabolism, which leads to generation of acetaldehyde. In this study the activity of ADH isoenzymes and ALDH in esophageal cancer were compared with the activity in normal tissue.

METHODS

For measurement of the activity of class I and II ADH isoenzymes and ALDH activity fluorimetric methods were employed. Total ADH activity and activity of class III and IV isoenzymes was measured by the photometric method. Samples were taken from 59 esophageal cancer patients (27 adenocarcinoma, 32 squamous cell cancer).

RESULTS

The total activity of ADH and activity of class IV ADH were significantly higher in cancer cells than in healthy tissues. The other tested classes of ADH showed a tendency toward higher activity in cancer than in normal cells. Differences between the activity of enzymes of drinkers and non-drinkers in both cancer and healthy tissue were not significant.

CONCLUSION

Increased ADH IV activity may be a factor intensifying carcinogenesis, because of the increased ability to form acetaldehyde from ethanol.

The activity of class I, II, III and IV of alcohol dehydrogenase (ADH) isoenzymes and aldehyde dehydrogenase (ALDH) in the wall of abdominal aortic aneurysms

OBJECTIVE

Human blood vessels contain a huge amount of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), which play a significant role in the metabolism of many biological substances and participate in various metabolic pathways. The aim of this study was the investigation of the differences between the activities of ADH and ALDH in the wall of aortic aneurysm and wall of healthy aorta, that can explain the pathological background of aneurysm development.

METHODS

For the measurement of the activity of class I and II ADH isoenzymes and ALDH activity the fluorometric methods was employed. The total ADH activity and activity of class III and IV isoenzymes was measured by the photometric method. The study material consisted of vessels wall samples obtained from 45 abdominal aortic aneurysm.

RESULTS

The activity of the class I ADH isoenzyme was significantly lower in the wall of aortic aneurysm than in healthy aorta. The other tested classes of ADH showed the tendency to lower level of the activity in aneurysm tissue than that in wall of unchanged aorta. The activities of total ADH and ALDH were also not significantly lower in the aneurysms.

CONCLUSION

The decrease of the activity of class I ADH isoenzymes in the wall of aortic aneurysm may be a factor of some disorders in metabolic pathways with participation of these isoenzymes.

Alcohol dehydrogenase isoenzymes and aldehyde dehydrogenase activity in the sera of patients with esophageal cancer

Various alcohol dehydrogenase (ADH) isoenzymes and aldehyde dehydrogenase (ALDH) exist in the human esophageal mucosa. In our last experiments we have shown that ADH and ALDH are present also in the esophageal cancer cells. Moreover, the activities of total ADH and class IV isoenzymes were significantly higher in cancer tissue than in healthy mucosa, which suggests that these changes may be reflected by enzyme activity in the serum. Therefore, we measured the activity of total alcohol dehydrogenase, and classes I-IV of this enzyme and aldehyde dehydrogenase in the sera of patients with this cancer. Serum samples were taken for routine biochemical investigation from 67 patients with esophageal cancer before treatment. Total ADH activity was measured by photometric method with p-nitrosodimethylaniline (NDMA) as a substrate and ALDH activity by the fluorometric method with 6-methoxy-2-naphtaldehyde as a substrate. For the measurement of the activity of class I and II isoenzymes, we employed the fluorometric methods, with class-specific fluorogenic substrates. The activity of class III alcohol dehydrogenase was measured by the photometric method with formaldehyde and class IV with m-nitrobenzaldehyde as a substrate. A statistically significant increase of class IV alcohol dehydrogenase isoenzymes was found in the sera of cancer patients. The median activity of this class isoenzyme in the total cancer group increased by about 26.5% (7.42 mU/l) in comparison to the control level (5.46 mU/l). The total alcohol dehydrogenase activity was significantly higher (30%) among patients with cancer. The activities of other tested ADH isoenzymes and total ALDH were unchanged. The activity of the class I ADH isoenzyme was significantly higher in the sera of drinkers with esophageal cancer than non-drinking patients. The increased total activity of alcohol dehydrogenase and class IV isoenzyme in the sera of patients with esophageal cancer probably can be caused by release of this isoenzyme from cancer cells or might be stimulated by alcohol drinking.

The activity of class I, II, III, and IV alcohol dehydrogenase (ADH) isoenzymes and aldehyde dehydrogenase (ALDH) in liver cancer

BACKGROUND

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), which are most abundant in the liver, are the main enzymes involved in ethanol and acetaldehyde metabolism.

AIMS

The purpose of this study was to compare the activity of ADH isoenzymes and ALDH between liver carcinoma cells and healthy hepatocytes.

PATIENTS

Samples were taken from 44 liver cancer patients (19 drinkers, 25 nondrinkers). Seventeen patients had primary liver tumors and 27 had metastatic liver tumors.

METHODS

Fluorimetric methods were used for measurement of the activity of class I and II ADH isoenzymes and ALDH activity. Total ADH activity and activity of class III and IV isoenzymes were measured by a photometric method.

RESULTS

The activities of total ADH, ALDH, and class I ADH were significantly higher in cancer cells than in healthy tissues. The other tested classes of ADH showed a tendency toward higher activity in cancer than in normal cells. The differences between enzymes of drinkers and nondrinkers in both cancer and healthy tissue, were not significant.

CONCLUSION

Differences in the activities of total ADH, ALDH and class I ADH isoenzyme between cancer liver tissues and healthy hepatocytes might be a factor in ethanol metabolism disorders, which can intensify carcinogenesis.

Alcohol dehydrogenase (ADH) isoenzymes and aldehyde dehydrogenase (ALDH) activity in the sera of patients with pancreatic cancer

BACKGROUND

Numerous experiments have shown that alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) are present in cells of various cancer and can play role in carcinogenesis. In previous investigations we have found elevated levels of alcohol dehydrogenase class III activity in pancreatic cancer cells. It can suggest that these changes may be reflected by enzyme activity in the serum.

AIM

In this paper we have measured the activity of alcohol dehydrogenase isoenzymes, and aldehyde dehydrogenase in the sera of patients with pancreatic cancer.

METHODS

Serum samples were taken for routine biochemical investigation from 56 patients with pancreatic cancer before treatment. Total ADH activity was measured by photometric method with p-nitrosodimethylaniline (NDMA) as a substrate, and ALDH activity by the fluorometric method with 6-methoxy-2-naphtaldehyde as a substrate. For the measurement of the activity of class I isoenzymes, we employed the fluorometric methods, with class-specific fluorogenic substrates. The activity of class III alcohol dehydrogenase was measured by the photometric method with n-octanol and class IV with m-nitrobenzaldehyde as a substrate.

RESULTS

A statistically significant increase of class III alcohol dehydrogenase isoenzymes was found in the sera of cancer patients. The median activity of this class isoenzyme in the total cancer group increased about 22% (13.52 mU/l) in the comparison with the control level (11.08 mU/l). The total alcohol dehydrogenase activity was significantly higher (19.7%) among patients with cancer than healthy ones. The activities of other tested ADH isoenzymes and total ALDH were unchanged. The activity of the class I ADH isoenzyme was significantly higher in the sera of drinkers with pancreatic cancer than non-drinkers.

CONCLUSION

The increased total activity of alcohol dehydrogenase and class III isoenzyme in the sera of patients with pancreatic cancer can be caused by release of this isoenzyme from cancer cells.

Alcohol dehydrogenase (ADH) isoenzymes and aldehyde dehydrogenase (ALDH) activity in the sera of patients with gastric cancer

BACKGROUND

Investigations have shown that alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) are present in some cancer cells and can play role in carcinogenesis. In recent experiments we found elevated alcohol dehydrogenase class IV activity in gastric cancer cells. This suggests these changes may be reflected by enzyme activity in the serum.

AIM

In this work we measured the activity of alcohol dehydrogenase isoenzymes and aldehyde dehydrogenase in the sera of patients with gastric cancer matched on gender.

METHODS

Serum samples were taken for routine biochemical investigation from 55 patients with gastric cancer, before treatment, and from 55 control subjects. Total ADH activity was measured photometrically and ALDH activity by a fluorimetric method. For measurement of the activity of class I isoenzymes we used a fluorimetric method, with class-specific fluorogenic substrates. The activity of class III and IV alcohol dehydrogenase was measured photometrically.

RESULTS

The activity of the class IV ADH isoenzyme was significantly higher in the sera of patients with gastric cancer. The median activity of this isoenzyme in the total cancer group was approximately 47% higher (7.45 mU/l) than the control level (5.08 mU/l). For this reason total ADH activity was also significantly increased. The activities of other tested ADH isoenzymes and ALDH were unchanged.

CONCLUSION

Changes in the activity of, especially, class IV ADH in the sera of patients with gastric cancer seems to be caused by release of the isoenzyme from cancer cells.

Alcohol dehydrogenase (ADH) isoenzymes and aldehyde dehydrogenase (ALDH) activity in the sera of patients with liver cancer

The principal enzymes catalyzing the conversion of ethanol to acetate are alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH). The activities of these enzymes are elevated in the serum during the course of alcoholism or cirrhosis. In previous investigations we have found elevated levels of ADH, ALDH, and class I ADH activity in liver cancer cells. It can suggest that these changes may be reflected by enzyme activity in the serum. In this work, the activity of ADH isoenzymes, and ALDH in the sera of patients with liver cancer was measured. Serum samples were taken from 64 patients (28 drinkers, 36 nondrinkers), with liver cancer. 25 patients had primary and 39 metastatic liver tumors. Total ADH activity was measured by photometric method with p-nitrosodimethylaniline (NDMA) as a substrate and ALDH activity by the fluorimetric method with 6-methoxy-2-naphtaldehyde as a substrate. For the measurement of the activity of class I and II isoenzymes we employed the fluorimetric methods, with class-specific fluorogenic substrates. The activity of class III ADH was measured by the photometric method with formaldehyde and class IV with m-nitrobenzaldehyde as a substrate. A statistically significant increase of class I ADH isoenzymes was found in the sera of cancer patients. The median activity of this class isoenzyme in the total cancer group increased about 51% (2.94 mU/L) in the comparison to the control level (1.43 mU/L). The activity of the class I ADH isoenzyme was significantly higher in the sera of patients with metastatic tumors than with primary cancers. The activity of this class in the sera of drinkers and group of moderate drinkers was significantly higher in comparison to the control group and higher in the sera of heavy drinkers when compared with moderate drinking patients. The total ADH activity was significantly higher (44%) among patients with cancer than healthy ones. The activity of class I ADH isoenzymes was elevated only in the serum of patients with metastatic liver cancer. This increase of activity seems to be caused by the enzyme released from liver cancer cells and primary tumors originating in other organs.

The activity of class I, II, III, and IV of alcohol dehydrogenase isoenzymes and aldehyde dehydrogenase in pancreatic cancer

OBJECTIVES

The pancreas can metabolize ethanol via oxidative pathway involving the enzymes alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) as well as the nonoxidative pathway. In this study, we compared the activity of ADH isoenzymes and ALDH in the pancreatic cancer with the activity in normal tissue. In addition, the differences between enzyme activities of drinkers and nondrinkers were compared.

METHODS

For the measurement of the activity of class I and II ADH isoenzymes and ALDH activity, we used the fluorometric methods. The total ADH activity and activity of class III and IV isoenzymes were measured by the photometric method. The samples were taken from 56 pancreatic cancer patients (22 drinkers and 34 nondrinkers) and 56 healthy subjects.

RESULTS

The activity of class III ADH was significantly higher in cancer than in healthy tissues. Total activities of ADH and ALDH were not significantly different in cancer and normal cells. The differences between enzymes of drinkers and nondrinkers in both cancer and healthy tissue were not significant.

CONCLUSION

Pancreatic cancer tissue exhibits higher activity of class III ADH isoenzyme than healthy tissue, and we consider that oxidative pathway of ethanol metabolism via ADH and ALDH does not play a role in pancreatic carcinogenesis.

Alcohol dehydrogenase (ADH) isoenzyme activity in the sera of patients with Helicobacter pylori infection

Human gastric mucosa contains three classes of alcohol dehydrogenase (ADH) isoenzymes: I, III, and IV. Various factors have been found to influence gastric ADH activity. One of them is Helicobacter pylori infection, which is associated with gastric mucosal injury and leads to a decrease in gastric ADH activity. The aim of the study was to assess the effect of H. pylori infection on the serum activity of ADH isoenzymes. Serum samples were taken from 35 patients with H. pylori infection and from 35 healthy subjects. For measurement of class I isoenzyme activity we employed the fluorometric method, with class-specific fluorogenic substrate (4-methoxy-1-naphthaldehyde). The activities of class III and IV ADH isoenzymes were measured by the photometric method with formaldehyde and with m-nitrobenzaldehyde as substrate, respectively. Total activity of ADH was measured by a photometric method with p-nitrosodimethylaniline. The total activities of ADH and class IV isoenzyme were significantly higher in sera of patients with H. pylori infection compared to healthy subjects. The serum activity of other tested isoenzymes of ADH did not differ significantly between infected and noninfected groups. We conclude that H. pylori infection of gastric mucosa is reflected in the serum by a significant increase in class IV and total ADH activity.

Overview of the role of alcohol dehydrogenase and aldehyde dehydrogenase and their variants in the genesis of alcohol-related pathology

Alcohol dehydrogenase (ADH) and mitochondrial aldehyde dehydrogenase (ALDH2) are responsible for metabolizing the bulk of ethanol consumed as part of the diet and their activities contribute to the rate of ethanol elimination from the blood. They are expressed at highest levels in liver, but at lower levels in many tissues. This pathway probably evolved as a detoxification mechanism for environmental alcohols. However, with the consumption of large amounts of ethanol, the oxidation of ethanol can become a major energy source and, particularly in the liver, interferes with the metabolism of other nutrients. Polymorphic variants of the genes for these enzymes encode enzymes with altered kinetic properties. The pathophysiological effects of these variants may be mediated by accumulation of acetaldehyde; high-activity ADH variants are predicted to increase the rate of acetaldehyde generation, while the low-activity ALDH2 variant is associated with an inability to metabolize this compound. The effects of acetaldehyde may be expressed either in the cells generating it, or by delivery of acetaldehyde to various tissues by the bloodstream or even saliva. Inheritance of the high-activity ADH β2, encoded by theADH2*2gene, and the inactiveALDH2*2gene product have been conclusively associated with reduced risk of alcoholism. This association is influenced by gene–environment interactions, such as religion and national origin. The variants have also been studied for association with alcoholic liver disease, cancer, fetal alcohol syndrome, CVD, gout, asthma and clearance of xenobiotics. The strongest correlations found to date have been those between theALDH2*2allele and cancers of the oro-pharynx and oesophagus. It will be important to replicate other interesting associations between these variants and other cancers and heart disease, and to determine the biochemical mechanisms underlying the associations.

The activity of class I, III, and IV of alcohol dehydrogenase isoenzymes and aldehyde dehydrogenase in gastric cancer

The metabolism of cancer is in many way different than in healthy cells. Increased metabolism of several carcinogenic substances may take place in cancer cells. The one of them was ethanol, that is oxidized by alcohol dehydrogenase (ADH) to high concentration of acetaldehyde, a toxic and carcinogenic compound. The enzyme responsible for oxidation of acetaldehyde is aldehyde dehydrogenase (ALDH). The aim of this study was to compare the capacity for ethanol metabolism measured by ADH isoenzymes and ALDH activity between gastric cancer and normal gastric mucosa. Total ADH activity was measured by photometric method with p-nitrosodimethylaniline (NDMA) as a substrate and ALDH activity by the fluorometric method with 6-methoxy-2-naphtaldehyde as a substrate. For the measurement of the activity of class I isoenzymes, we used fluorometric methods, with class-specific fluorogenic substrates. The activity of class III ADH was measured by the photometric method with n-octanol and class IV with m-nitrobenzaldehyde as a substrate. The samples were taken surgically during routine operations of gastric carcinomas from 55 patients. The activities of total ADH, and the most important in gastric mucosa, class IV ADH were significantly higher in cancer cells than in healthy tissues. The other tested classes of ADH and ALDH showed a tendency toward higher activity in cancer than in healthy mucosa. The activities of all tested enzymes and isoenzymes were not significantly higher in men than in women in wither gastric cancer tissues or normal mucosa. The increased ADH IV activity may be 1 of the factors intensifying carcinogenesis by the increased ability to acetaldehyde formation from ethanol.

Retinoic acid formation from retinol in the human gastric mucosa: role of class IV alcohol dehydrogenase and its relevance to morphological changes

Alcohol dehydrogenase (ADH) participates in the formation of retinoic acid from retinol in various organs including the gastric mucosa. However, its clinical significance still remains to be clarified. In this study, we identified the ADH isoforms responsible for the retinoic acid formation among various ADH isoforms and examined associations among the ADH activities, the retinoic acid formation level, and morphological changes in the human gastric mucosa. Human gastric samples were endoscopically obtained from 67 male subjects. Morphological changes were assessed by the Sydney system and activities of class I, III, and IV ADH isoforms were determined in each specimen. In 26 cases, levels of all-trans retinoic acid (ATRA) formation from all-trans retinol were examined. Among activities of the three ADH isoforms, class IV ADH activity was solely associated with the ATRA formation level. This association was found even when subjects' age and Helicobacter pylori infection status were adjusted. As the degrees of inflammation, atrophy, and intestinal metaplasia increased, the class IV ADH activity as well as the potential for the ATRA formation decreased. Class IV ADH is a major enzyme in the retinoic acid supply in the human gastric mucosa, and the reduction of its activity was associated with decreasing retinoic acid supply and progression of inflammation, atrophy, and intestinal metaplasia in the gastric mucosa. In that retinoic acid is a key molecule for maintaining normal morphology, the reduction of class IV ADH activity may be involved in the pathogenesis of these morphological changes in the human gastric mucosa.

Metabolism of alcohol

Most tissues of the body contain enzymes capable of ethanol oxidation or nonoxidative metabolism, but significant activity occurs only in the liver and, to a lesser extent, in the stomach. Hence, medical consequences are predominant in these organs. In the liver, ethanol oxidation generates an excess of reducing equivalents, primarily as NADH, causing hepatotoxicity. An additional system, containing cytochromes P-450 inducible by chronic alcohol feeding, was demonstrated in liver microsomes and found to be a major cause of hepatotoxicity.

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.

A review and assessment of potential sources of ethnic differences in drug responsiveness

The International Conference on Harmonization (ICH) E5 guidelines were developed to provide a general framework for evaluating the potential impact of ethnic factors on the acceptability of foreign clinical data, with the underlying objective to facilitate global drug development and registration. It is well recognized that all drugs exhibit significant inter-subject variability in pharmacokinetics and pharmacologic response and that such differences vary considerably among individual drugs and depend on a variety of factors. One such potential factor involves ethnicity. The objective of the present work was to perform an extensive review of the world literature on ethnic differences in drug disposition and responsiveness to determine their general significance in relation to drug development and registration. A few examples of suspected ethnic differences in pharmacokinetics or pharmacodynamics were identified. The available literature, however, was found to be heterologous, including a variety of study designs and research methodologies, and most of the publications were on drugs that were approved a long time ago.

Gender-related differences in hepatic activity of alcohol dehydrogenase isoenzymes and aldehyde dehydrogenase in humans

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), which are most abundant in the liver, are the main enzymes involved in ethanol metabolism in humans. Gender-related differences in total liver ADH and ALDH activity among different animal species have been observed in many studies. We measured total ADH and ALDH activity, and the activity of class I-IV ADH in the livers of male and female patients. Total ADH and class I and II ADH activities were significantly higher in males than in females (P=0.0052, P=0.0074, P=0.020, respectively). Class III and IV ADH and total ALDH activities were not significantly different between the genders (P=0.2917, P=0.0590, P=0.2940, respectively). The results of our study clearly show that there is a difference in enzymatic activity between male and female patients for those isoenzymes that actively participate in ethanol oxidation in the liver (class I and II ADH), although the main form of ADH in this organ is class III ADH.

Alcohol metabolism: role in toxicity and carcinogenesis

This article contains the proceedings of a symposium at the 2002 RSA Meeting in San Francisco, organized and co-chaired by Thomas M. Badger, Paul Shih-Jiun Yin, and Helmut Seitz. The presentations were (1) First-pass metabolism of ethanol: Basic and clinical aspects, by Charles Lieber; (2) Intracellular CYP2E1 transport, oxidative stress, cytokine release, and ALD, by Magnus Ingelman-Sundberg; (3) Pulsatile ethanol metabolism in intragastric infusion models: Potential role in toxic outcomes, by Thomas M. Badger and Martin J.J. Ronis; (4) Free radicals, adducts, and autoantibodies resulting from ethanol metabolism: Role in ethanol-associated toxicity, by Emanuele Albano; and (5) Gastrointestinal metabolism of ethanol and its possible role in carcinogenesis, by Helmut Seitz.

Human class IV alcohol dehydrogenase: kinetic mechanism, functional roles and medical relevance

Human alcohol dehydrogenase (ADH) constitutes a complex family. Class IV ADH (ADH4) is characteristic in its epithelial expression in the aerodigestive tract and high V(max) and K(m) for oxidation of ethanol. ADH4 exhibits the highest catalytic efficiency for retinol oxidation in human ADH family. Initial velocity, product inhibition, and dead-end inhibition studies indicate that ADH4, when functioning as ethanol dehydrogenase, conforms to an ordered sequential mechanism with coenzyme binding first and releasing last in catalytic cycle. When functioning as retinol dehydrogenase, the mechanism of ADH4 deduced from steady-state kinetic and equilibrium-binding studies is best described as a rapid equilibrium random mechanism with two dead-end ternary complex for retinol oxidation and a rapid equilibrium ordered mechanism with one dead-end ternary complex for retinal reduction, a unique mechanistic form for zinc-containing ADHs in the medium chain dehydrogenase/reductase superfamily. Kinetic and genetic studies support the proposal that ADH4 may play two important physiological roles, i.e., as a major contributor to first-pass metabolism of ethanol in stomach as well as involvement in the synthesis of retinoic acid, a hormonal ligand controlling a nuclear receptor signaling pathway that regulates growth, development, and epithelial maintenance. Quantitative simulation studies indicate that retinol metabolism through ADH pathway can be inhibited to a significant extent during alcohol consumption. The perturbation of retinoic acid synthesis by ethanol may underlie the pathogenesis of fetal alcohol syndrome and alcohol-related upper digestive tract cancer.