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F J Chou

Publications and source records attributed to F J Chou.

3 recordsLinked to original sources
PubMed1993

Alcohol and aldehyde dehydrogenases in human esophagus: comparison with the stomach enzyme activities.

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) isoenzymes from surgical esophageal and gastric mucosa were compared by agarose isoelectric focusing. Two prominent ADH forms, designated mu 1 (equivalent to the recently reported mu-form) and mu 2, were expressed in all the 15 esophagus specimens studied, whereas only four of seven examined gastric specimens exhibited a weak to moderately strong mu 1-ADH activity band on the isoelectric focusing gels. pI values of the esophageal mu 1-ADH and mu 2-ADH, and the liver pi-ADH were determined to be 8.61, 8.13, and 8.90, respectively. mu-ADHs exhibited high Km for ethanol (12 mM) and low sensitivity to 4-methylpyrazole inhibition. ALDH3 (BB form) and ALDH1 were the major high- and low-Km aldehyde dehydrogenase in the esophagus, respectively. The ADH and ALDH activities were determined at pH 7.5 to be 751 +/- 78 and 29.9 +/- 3.0 nmol/min/g tissue, respectively (measured at 500 mM ethanol or at 200 microM acetaldehyde; mean +/- SEM; N = 15). The esophageal ADH activity was approximately 4-fold and the ALDH activity 20% that of the stomach enzyme. Because the presence of high activity and high Km mu-ADHs as well as low-activity ALDH1 were found in human esophageal mucosa, it is suggested that there may exist an accumulation of intracellular acetaldehyde during alcohol ingestion. This reactive and toxic metabolite may be involved in the pathogenesis of alcohol-induced esophageal disorders.

Aged↗
PubMed1989

Lung alcohol and aldehyde dehydrogenase isoenzymes in Chinese.

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) isoenzyme phenotypes were determined in 53 surgical lung specimens by isoelectric focusing. ADH isoenzymes containing beta subunits, but no alpha, gamma or pi subunits, were found present in human lungs. Ninety percent of the lung specimens exhibited a pH-optimum for ethanol oxidation at pH 8.5, instead of 10.5 which is usual among Caucasians. The homozygous ADH2 2-2 phenotype was found to be 60%, and the heterozygous ADH2 2-1 phenotype, 30%. The remaining 10% of the lungs, exhibiting a pH-optimum 10.5, was homozygous ADH2 1-1 phenotype. Accordingly, the gene frequencies of the alleles ADH2(2) and ADH1(2) were calculated to be 0.75 and 0.25, respectively. Fifty-five percent of the 53 lungs examined possessed both the activities of ALDH I and ALDH II isoenzymes, whereas 45% lacked the ALDH I activity. The ADH activities in homogenate supernatants of the lungs with phenotypes ADH2 2-2 or ADH2 2-1 were considerably greater than those with ADH2 1-1 phenotypes. The ALDH activities were significantly higher in the ALDH I-positive lungs than in the ALDH I-negative groups. The implications of these distributions of lung ADH and ALDH isoenzyme composition and activity among Orientals for ethanol metabolism and toxicity are discussed.

Adult↗