Shoji Harada

Racial differences in alcohol sensitivity: a new hypothesis.

SummaryA hypothesis regarding alcohol sensitivity in Japanese due to a polymorphism of liver aldehyde dehydrogenase (ALDH) is presented. ALDH was found to show two major bands, a faster migrating isozyme with a low Km for acetaldehyde and a slower migrating isozyme with a high Km for acetaldehyde. Out of 40 livers of Japanese, 21 had only the slower migrating isozyme. No such variation was detected in 68 autopsy livers of Germans. Our data suggest that the initial alcohol sensitivity, quite common in individuals of Mongoloid origin, might be due to a delayed oxidation of acetaldehyde rather than its higher than normal production by atypical alcohol dehydrogenase.

Electrophoretic and biochemical studies of human aldehyde dehydrogenase isozymes in various tissues

Abstract Four major ALDH isozymes have been identified in human tissues using starch gel electrophoresis and isoelectric focusing. The isozyme bands have been termed as ALDH I, II, III and IV according to their decreasing electrophoretic migration and increasing isoelectric point. The isozymes have been partially purified via preparative isoelectric focusing. Kinetic characteristics of ALDH I and II were found to be quite similar to ALDH enzyme 2 and enzyme 1 described earlier by Greenfield and Pietruszko (Biochem Biophys Acta, 483 35–45 1977). ALDH III and IV showed a very high Km for propionaldehyde (1.0–1.5 mM at pH 9.5) and were not inhibited by disulfiram at pH 9.5. A variant phenotype of ALDH which lacked in isozyme I was detected in various tissues from Japanese individuals. Comparative kinetic properties of normal and variant enzyme are given.

Isozyme variations in acetaldehyde dehydrogenase (E.C.1.2.1.3) in human tissues

SummaryNAD-dependent acetaldehyde dehydrogenase (ALDH) of human tissues was investigated by electrophoresis and enzyme assay. ALDH is located mainly in the liver and kidney. The isozymes consist of at least six different components. Five different phenotypes were found in a total of 68 human liver and kidney specimens. It is likely that three isozyme sets are concerned in determining ALDH types. The distribution of various phenotypes of ALDH isozyme sets is presented.

Alcohol metabolizing enzymes: studies of isozymes in human biopsies and cultured fibroblasts.

Rapid and sensitive micromethods for the study of alcohol dehydrogenase and aldehyde dehydrogenase isozymes in skin extracts, cultured fibroblasts and other organs are presented. Possibilities for the application of these techniques to the study of interindividual variations in response to alcohol are discussed. While fibroblasts cultured from a skin biopsy from one Japanese individual revealed a heterodimer (ADH22‐1) of alcohol dehydrogenase, skin extract from another Japanese showed a homodimer (ADH22‐2). Up to four isozyme sets for aldehyde dehydrogenase (ALDH) were detected in various human organs and at least three sets were found in skin and fibroblast extracts. Our preliminary data on liver, stomach, and skin indicate that ALDH is polymorphic and several loci are concerned in the determination of these isozyme sets.

Comparative study of erythrocyte aldehyde dehydrogenase in alcoholics and control subjects.

Human erythrocyte aldehyde dehydrogenase (ALDH, EC 1.2.1.3) shows a single activity band on starch gel electrophoresis and isoelectric focusing in polyacrylamide gel (pI = 5.0-5.3). The erythrocyte enzyme is identical with the slower migrating, disulfiram-sensitive human liver ALDH isozyme II. Significantly decreased activity of erythrocyte ALDH was observed in chronic alcoholics when compared with healthy controls and non-alcoholic psychiatric and gastrointestinal patients. The measurement of ALDH in erythrocyte lysates may offer yet another sensitive and specific biochemical marker of alcoholism.

Human liver alcohol dehydrogenase isoenzyme variations

SummaryHuman liver alcohol dehydrogenase isozyme patterns were studied using prolonged high voltage starch-gel electrophoresis and gel-slab isoelectric focusing. Homo- and heterodimers of ADH2 locus were easily distinguished from each other. The gene frequencies of ADH22and ADH32in 46 random liver samples from Germany were found to be 0.044 and 0.424 respectively.

Population genetic and family studies on aldehyde dehydrogenase deficiency and alcohol sensitivity

Population genetic studies on the prevalence of aldehyde dehydrogenase isozyme I (ALDH I) deficiency in various Caucasian, Oriental, African, and American Indian subjects were carried out using hair roots as peripheral source of the enzyme activity. While a very high percentage of Orientals with Mongoloid origin were found deficient in ALDH I activity, no deficiency was detected in Caucasian and African populations. Native American Indians showed a relatively low incidence of ALDH I deficiency. A genetic model based on the phenotype determination using antisera against purified human liver ALDH I is proposed. Pedigree analysis of Japanese families suggests an autosomal codominant mode of inheritance.

Isozymes of Alcohol Dehydrogenase and Aldehyde Dehydrogenase in Japanese and their Role in Alcohol Sensitivity

Racial differences in alcohol sensitivity have been described by many authors (Wolff, 1973; Ewing et al., 1974). Variant forms of alcohol metabolizing enzymes have been proposed to play an important role in sensitivity to alcohol associated with facial flushing and other subjective symptoms (Stamatoyannopoulos et al., 1975; Goedde et al., 1979b; Harada et al., 1979).

Basis of aldehyde dehydrogenase deficiency in Orientals: Immunochemical studies☆☆☆

While most Caucasians have two main isozymes of liver aldehyde dehydrogenase, in about 50% of Orientals the ALDH I isozyme is missing. This isozyme, which has a faster electrophoretic mobility, is predominantly present in mitochondria and has a relatively low Km for acetaldehyde. The inherent deficiency of ALDH I is responsible for the impaired acetaldehyde oxidation leading to facial flushing and other cardiovascular symptoms of alcohol sensitivity commonly observed in Japanese and Chinese. Antibodies raised against apparently homogeneous liver ALDH I and ALDH II isozymes did not show an immunological similarity between the two isozymes which do not share common subunits. While erythrocyte ALDH II is also immunologically distinct from hepatic ALDH I, it showed an immunological similarity with hepatic ALDH II. On isoelectric focusing in agarose gel followed by immunoelectrophoresis, at least 4 components with an anti-ALDH I antibody were detected in extracts from Caucasian and Oriental livers. In Japanese livers deficient in ALDH I activity, the prominent ALDH component was missing. Apparently, more than one gene is responsible for the synthesis of ALDH isozymes reacting with an antibody against ALDH I. A deletion in one of the genes may be responsible for the loss of ALDH I enzyme activity and altered antigenic properties. However, at this stage, a point mutation in a structural gene coding for ALDH I resulting in a defective protein with altered electrophoretic and enzymatic properties is not ruled out.

Association analyses of genetic polymorphisms of GSTM1, GSTT1, NQO1, NAT2, LPL, PRSS1, PSTI, and CFTR with chronic alcoholic pancreatitis in Japan.

BACKGROUND Excessive consumption of alcohol is involved in the onset of pancreatitis. However, most of heavy drinkers do not always develop chronic pancreatitis. Various genetic factors appear to be involved in these individual differences in onset of chronic alcoholic pancreatitis. Here we investigated a possible association of alcoholic pancreatitis with polymorphisms of the various genes belong to the phase II detoxification enzymes responsible for metabolism of the oxidative compounds, and the several genes that have relevance to inherited pancreatitis. METHODS The subjects consisted of 53 patients with chronic alcoholic pancreatitis, 54 alcoholic patients without pancreatic dysfunction, and 42 healthy individuals. DNA was extracted from the peripheral nucleated blood cells of all subjects and genetic mutations and subtypes were analyzed by the PCR and RFLP methods. We examined the correlation between chronic alcoholic pancreatitis and variants of the phase II detoxification enzymes such as Glutathione S-transferase M1 (GSTM1), glutathione S-transferase theta 1 (GSTT1), NADPH-quinone oxidoreductase 1 (NQO1), and N-acetyl transferase (NAT2). In addition, genes of lipoprotein lipase (LPL), cationic trypsinogen (PRSS1), pancreatic secretory trypsin inhibitor (PSTI), and cystic fibrosis transmembrane conductance regulator (CFTR) were also analyzed. RESULTS Frequencies of the gene deletion of GSTM1 and GSTT1 in addition to the C-allele frequency of NQO1 tended to be higher in the alcoholic patients with (AlCP) or without pancreatic dysfunction (Alc) than in the healthy controls although the difference was not significant. The NAT2 gene showed no relation with Alc and AlCP patients. PSTI, LPL, PRSS1, and CFTR genes presented no association with chronic alcoholic pancreatitis. CONCLUSIONS All genes analyzed in the present study lacked association with chronic alcoholic pancreatitis. However, the gene deletion of GSTM1 and GSTT1, and the C-allele of NQO1 cannot be ruled out for association with alcoholism.