Yohsuke Shigeta

Hepatic and intestinal gamma-glutamyltranspeptidase activity: Its activation by chronic ethanol administration

Abstract To study the effect of chronic ethanol administration on the activity of gamma-glutamyltranspeptidase (GGTP) in various tissues, female rats were pair-fed liquid diets with 36% of total calories either as ethanol or isocaloric carbohydrate (controls). Six weeks of ethanol feeding in an increase of cytochrome P450 content by 70%. Hepatic microsomal GGTP activity was more than doubled after ethanol feeding whether expressed per gram of liver or per mg of microsomal protein. Furthermore intestinal GGTP activity was significantly enhanced after ethanol, whereas there was no change in the enzyme activity in either kidney or pancreas. Phenobarbital administration to rats also resulted in an enahancement of GGTP activity in the liver but not in the intestine. These results suggest that enhanced hepatic and intestinal GGTP activities may contribute, at least partly, to increased serum GGTP activity frequently seen in alcoholics.

Significance of serum gamma glutamyl transpeptidase as a marker of alcoholism

To study the effect of chronic ethanol administration on the activity of gamma glutamyl transpeptidase (GGTP) in various tissues, female rats were pair-fed liquid diets with 36% of total calories either as ethanol or as isocaloric carbohydrate (controls). Six weeks of ethanol feeding resulted in a significant increase of cytochrome P450 content. Hepatic microsomal GGTP activity was almost doubled after ethanol feeding whether expressed per g of liver or per mg of microsomal protein. Furthermore, intestinal GGTP activity was significantly enhanced after ethanol, whereas there was no change in the enzyme activity in either kidney or pancreas. There was a concomitant elevation of plasma GGTP activity. Phenobarbital administration to rats resulted in an enhancement of GGTP activity in the liver whether given orally or intraperitoneally. In addition, intestinal GGTP activity after oral phenobarbital was also significantly increased, although its activity after intraperitoneal administration was not enhanced. These results suggest that enhanced hepatic and intestinal GGTP activities may contribute, at least in part, to an increased level of serum GGTP frequently seen in chronic alcoholics.

HLA antigens as immunogenetic markers of alcoholism and alcoholic liver disease

HLA antigens were studied among 94 chronic alcoholics. Concerning A and B-loci, there was no significant change of phenotype frequency (PF) in the HLA typing between the patients and controls (80 healthy subjects). However, there was a significant difference in the PF of CW3 between chronic alcoholics and controls (58.5% in alcoholics vs 30.0% in controls). The corrected p value was less than 0.05 with relative risk value being 3.29 HLA-DR loci were also detected in 26 patients, but there was no significant difference between the patients and controls. All alcoholics were subdivided according to the hepatic morphology, and the PF of HLA was examined. A significant high frequency of HLA CW3 was found in patients with hepatitis (64%) compared to controls (30%). There was also an increased PF of CW3 in the liver cirrhosis group (59% in cirrhosis group vs 30% in controls). In conclusion, chronic alcoholics have a significantly higher PF of HLA-CW3 as compared to controls. This characteristic feature becomes even more distinct in alcoholics with severe hepatic lesions.

Increase in mitochondrial GOT (m-GOT) activity after chronic alcohol consumption: clinical and experimental observations

In order to clarify the origin and the mechanism of increased serum activity of glutamic oxalacetic transaminase (GOT) in chronic alcoholics, clinical and experimental investigations were carried out. Mitochondrial (m-GOT) and cytosolic GOT (c-GOT) isoenzymes were separated chromatographically by using a mini-column packed with Sephadex A50. Sixty percent of 63 alcoholics had elevated serum GOT. The m-GOT activity in alcoholics with total serum GOT activity of over 50 Karmen Units was 17.2 +/- 1.6 K.U. and the m-GOT/GOT ratio was the highest when compared to those in non-alcoholic liver diseases. In in vitro study, six hours of incubation of isolated hepatocytes from rats fed ethanol chronically resulted in an increased leakage of m-GOT into the incubation medium and also showed a tendency of a higher m-GOT/GOT ratio than that from control rats. The m-GOT activity thus released into the medium showed a highly significant inverse correlation with the viability of hepatocytes. These data suggest that m-GOT substantially contributes to an increased serum GOT often observed in chronic alcoholics.

Alcohol dehydrogenase: A new sensitive marker of hepatic centrilobular damage☆

To determine whether serum alcohol dehydrogenase (ADH) activity reflects hepatic damage of centrilobular region (zone 3), the rats were given either bromobenzene (BB) or allyl alcohol (AA) IP to produce the pericen tral or periportal necrosis respectively. After AA or BB serum alanine aminotransferase (ALT) activity showed no significant difference between the two groups. By contrast, serum ADH and glutamate dehydrogenase (GLDH) activities were elevated preferentially in the BB treated rats. However, AA administration to rats also resulted in a significant increase in GLDH activity, whereas ADH activity was only slightly elevated when compared to controls. Moreover, acute ethanol administration to rats resulted in a significant elevation of the serum ADH activity, whereas serum GLDH and ALT activities remained normal. These data suggest that serum ADH activity appears to be a sensitive and specific marker of hepatic centrilobular damage.

Mild but prolonged elevation of serum angiotensin converting enzyme (ACE) activity in alcoholics

Serum activity of angiotensin converting enzyme (ACE) was serially measured in 47 hospitalized chronic alcoholics with liver disease. Compared to healthy controls, ACE activity, on admission, in the serum of alcoholics was significantly elevated (42.5 +/- 16.6 U/ml vs. 32.4 +/- 9.6 U/ml; p less than 0.005). About 36% of the patients had an elevated ACE level exceeding an upper normal value of 42 U/ml (mean +/- SD). In contrast to the rapid normalization of such enzymes as aspartate transaminase (AST), alanine transaminase (ALT) and lactic dehydrogenase (LDH) which represent parenchymal liver cell injury, the activity of ACE remained elevated over a period of 4 weeks even with abstinence. The serum level of ACE was significantly correlated with levels of alkaline phosphatase, gamma-glutamyltranspeptidase and monoamine oxidase, but not with those of AST, ALT and LDH. These data suggest increased ACE activity in alcoholics may be related to the influence of chronic consumption of alcohol on hepatic nonparenchymal systems.

Association of HLA-B40 and DRW9 with Japanese alcoholic liver cirrhosis

Seventy-seven chronic alcoholics with liver disease were studied to evaluate the HLA antigen association. There were no significant differences of HLA antigen phenotype frequencies (PF) between the patients and controls regarding A and C loci, (62 healthy Japanese). Prevalences of HLA-B40 complex (B40 . 48 . 13) and DRW9 tended to increase among chronic alcoholics. When chronic alcoholics were divided according to whether they had liver cirrhosis or not, the cirrhosis group (42 cases) revealed a significantly higher frequency of HLA-DRW9 (chi 2 = 10.88, p less than 0.001, corrected p less than 0.05, relative risk (R.R.) = 4.17) as compared to controls. There was also a tendency of B40 complex to increase in frequency (chi 2 = 5.51, p less than 0.05, R.R. = 2.65) in the cirrhosis group. Haplotype frequency and linkage disequilibrium parameters of HLA-B40 . 48-DRW9 were significantly higher than those of controls. Moreover, the increased frequency of DRW9 in the cirrhosis group was similar to that in autoimmune disease like ulcerative colitis or SLE. These data suggest that HLA-DRW9 and/or HLA-B40-DRW9 might be closely associated with susceptibility to developing alcoholic cirrhosis and that autoimmune mechanisms might be involved partly in its etiology.

Microsomal drug metabolism in acute and chronic galactosamine induced hepatic injuries

SummaryTo determine the microsomal functions of the injured liver, female rats were given D-galactosamine (GalN) acutely (400 mg/kg body weight, i.p.) or chronically (250 mg/kg body weight for 7 months, daily, i.p.). In the acute study, GalN administration resulted in a five-fold increase in hepatic triglyceride content. Microsomal protein and phospholipid concentrations were not affected. However microsomal cytochrome P450 content and aminopyrine demethylase and also aniline hydroxylase activities were significantly decreased whether expressed per mg of microsomal protein or per gram of liver. Cytochrome b5 content was significantly increased. By contrast, chronic administration of GalN produced a marked hepatomegaly and an extensive hepatic fibrosis with nodular formation without triglyceride accumulation. Electron-microscopically, there was apparent proliferation of mitochondria, and smooth endoplasmic reticulum showed focally accentuated hypertrophy without liposomes in the dilated tubules. Although microsomal protein concentration was significantly decreased, cytochrome P450 content was increased significantly when expressed per mg of microsomal protein or per unit of body weight. The aminopyrine demethylase activity was significantly enhanced only when expressed per unit of body weight. In both acute and chronic studies, microsomal glucose-6-phosphatase activity was significantly reduced. These data suggest that in acute liver injury, there is an impairment of hepatic microsomal drug metabolizing activity, whereas in chronic liver injury, there is an apparent enhancement of the activity possibly due to an enlarged hepatic mass even in the presence of a decreased drug metabolizing capacity per unit of the injured liver.