Glutathione metabolism and glucose 6-phosphate dehydrogenase activity in experimental liver injury.

Increased activities of liver glucose-6-phosphate dehydrogenase (G6PD, EC 1.1.1.49) and 6-phosphogluconate dehydrogenase (6PGD, EC 1.1.1.44) in the pentose phosphate cycle were accompanied with a depletion of reduced glutathione (GSH) following an intragastric administration of carbon tetrachloride (CCl4) to rats. Oxidized glutathione (GSSG) also decreased remarkably, keeping the GSSG: GSH ratio constant. No significant alteration of glutathione reductase (EC 1.6.4.2.), glutathione peroxidase (EC 1.11.1.9) and malic enzyme (EC 1.1.1.40) activities in the supernatant and gamma-glutamyl transpeptidase (gamma-GTP, EC 2.3.2.2) activity in the homogenate of the injured liver were observed. Furthermore, no marked difference in the GSH-synthesizing activity was found between control and CCl4-intoxicated liver. An intraperitoneal injection of GSH produced a significant increase in liver GSH content in control rats but not in CCl4-treated rats; G6PD activity was not affected. Intraperitoneal injections of diethylmaleate resulted in continuously diminished levels of liver GSH without any alteration of liver G6PD activity. In vitro disappearance of GSH added to the liver homogenate from CCl4-treated rats occurred enzymatically and could not be prevented by the addition of a NADPH-generating system. The results suggest that increased G6PD activity in CCl4-injured liver does not play an important role in the maintenance of glutathione in the reduced form and that the decreased GSH content in the injured liver might be caused by enhanced GSH catabolism not due to gamma-GTP.</p

Elevation of Collagenase Activity in Fatty Liver

Liver collagenase activity increased without liver cell necrosis in non-alcoholic and alcoholic fatty liver induced by feeding rats a choline-deficient diet or alcohol-liquid diet, respectively. The liver hydroxyproline content did not increase during a marked rise in collagenase activity in non-alcoholic fatty liver, but the content gradually increased after collagenase activity diminished. However, the hydroxyproline content increased slowly with a slight concomitant increase in collagenase activity in alcoholic fatty liver. The regulatory mechanism of fibrogenesis in fatty liver is discussed

Immunological properties of two fetus-specific globulins of rat in experimentally induced hepatic lesions

Two fetus-specific globulins, al and a2·fetoglobulins, were detected in rat fetal serum, and the former was detected in amniotic fluid, using respective monospecific rabbit immune sera. Immunochemical distinction of these two proteins was demonstrated. By polyacrylamide gel disc electrophoresis, al-fetoglobulin was further resolved into fast and slow migrating subcomponents having a similar reactivity against the specific immune serum. The concentrations of these globulins in the serum of adult rat with experimentally induced hepatic lesions were determined by quantitative immunoprecipitin method or the Ouchterlony test using the specific antisera.</p

Demonstration of enzymatic activity converting azathioprine to 6-mercaptopurine

The enzymatic conversion of azathioprine to 6-mercaptopurine was detected at pH 6.5 with rat liver supernatants, although the non-enzymatic reaction predominated at pH 7.0 and 7.5. Glutathione S-transferase may catalize this conversion. Activities of the enzyme in liver with both zathioprine and 1,2-dichloro-4-nitrobenzene as substrate decreased upon carbon tetrachloride-induced hepatic injury. These results may explain an ineffectiveness of azathioprine in patients with severe hepatic damage.</p

An approach to nutritional therapy of hepatic encephalopathy by normalization of deranged amino acid patterns in serum

A mixture with essential and nonessential amino acids high in branched chain amino acids and low in aromatic amino acids (Fischer solution), and another synthetic mixture of branched chain amino acids containing 3 amino acids associated with the urea cycle (Hep-OU) were infused to control subjects and patients with severe hepatic disease. Alterations in serum aminograms, blood ammonia levels and electroencephalograms following the infusion were studied and compared with those obtained by a commercially available amino acid mixture. Short-term or continuous infusion of a commercially available amino acid solution to cirrhotic patients caused an increase in methionine, phenylalanine and tyrosine and a decrease in branched chain amino acids. These post-infusion results were similar to the patterns seen in hepatic encephalopathy. In cirrhotic patients, infusion of Fischer solution which contains small quantities of methionine and phenylalanine produced an increase in the concentrations of these 2 amino acids, probably because of impaired utilization by the injured liver. No marked alterations in serum aminograms, however, were observed in cirrhotic patients either immediately after, or 3 h after, the end of the Hep-OU infusion. Reduction of methionine, tyrosine and phenylalanine levels and elevation of the molar ratio of (valine+leucine+isoleucine) / (phenylalanine+tyrosine) were significant. The infusion of Hep-OU to patients with liver cirrhosis or subacute hepatitis resulted in clinical and neurological improvements and the restoration of the molar ratio of branched chain amino acids/aromatic amino acids.</p

A vegetable protein-rich diet for the treatment of liver cirrhosis

Twelve patients were administered a vegetable protein-rich diet, which was low in methionine and high in the branched-chain amino acid (BCAA) to aromatic amino acid (AAA) molar ratio, and an animal protein-rich diet, high in methionine and low in the BCAA/AAA molar ratio. These diets were administered successively for one week each. Actually ingested amounts of tyrosine and methionine were significantly lower during the feeding of the vegetable protein-rich diet than the animal protein-rich diet. Serum methionine concentrations increased while on the animal protein-rich diet and decreased following the switch to the vegetable protein-rich diet. No other amino acid concentrations were affected. Significant differences were not observed in nitrogen balance or serum protein concentrations.</p

Anti-Carcinogenic Effects of a Serine Protease Inhibitor (FOY-305) through the Suppression of Neutral Serine Protease Activity During Chemical Hepatocarcinogenesis in Rats

Anti-carcinogenic effect of a serine protease inhibitor, [N, N-dimethylcarbamoylmethyl 4-(4-guanidinobenzoyloxy)-phenylacetate] methanesulfate (FOY-305), was studied in rats with neutral serine protease during hepatocarcinogenesis induced by a single intraperitoneal administration of diethylnitrosamine (DEN) and following feeding of a diet containing 2-N-fluorenylacetamide (FAA) for 32 weeks. Oral administration of FOY-305 significantly suppressed development of -γ-glutamyl transpeptidase (γ-GTP)positive hyperplastic nodules, preneoplastic lesion, at the 8th week of DEN injection, and that of hepatocellular carcinoma (HCC) formation at the 32nd week. Neutral protease activity increased in the preneoplastic and neoplastic livers. The activities in the preneoplastic and tumor-bearing livers were much lower in FOY-305-treated group compared with those in control group. Neutral protease partially purified from neoplastic liver at the 32nd week was inhibited by FOY-305 in vitro. The data suggest that neutral protease plays a crucial role in the process of chemical hepatocarcinogenesis

Purification and immunochemical characterization of alpha-fetoprotein from rat fetal serum and liver

Two alpha1-globulin bands of fetal serum with relative mobilities against bromophenol blue of 0.55 and 0.58 on 7% polyacrylamide gel electrophoresis reacted with a monospecific rabbit antiserum to alpha-fetoprotein (AFP). The former globulin band was clearly detected in the fetal liver supernatant. AFP was immunochemically purified from both the fetal serum and liver, and their electrophoretic and immunochemical properties were compared. Liver AFP purified by immunoadsorbent column yielded electrophoretic mobilities and relative amounts of the two electrophoretically distinct components identical with the purified serum AFP. The immunological reactivity of the two components of the purified preparations from serum and liver against the monospecific anti-AFP serum was also indistinguishable. After the removal of the sialic acid residues from purified serum and liver AFP by treatment with neuraminidase for 6 to 12 hr, disc electrophoretic patterns on 5% polyacrylamide gel and immunoelectrophoretic patterns of the treated AFP were found to be closely similar in both preparations. It may be possible to conclude that serum and liver AFP are structurally indistinguishable and probably identical.</p

Liver Injury Following Long-Term Administration of Large Doses of Sake to Rats

The hepatotoxic effect on rats of long-term (55 weeks) administration of sake (a rice wine, 17% ethanol by volume) at large doses (average 12.6 g ethanol/kg body weight/day) was investigated in order to gain an insight into the reasons for the high incidence of liver fibrosis in Japanese alcoholics. Rats grew favorably under the experimental conditions, and daily variations in blood ethanol and acetaldehyde levels ranged from 3.8 to 21.1 mM and from O to 3.5 μM, respectively. Fatty and fibrotic liver was shown histologically and biochemically in sake-administered rats