Akiharu Watanabe

Serum amino acid levels in patients with hepatocellular carcinoma.

Serum amino acid concentrations in cirrhotic patients with and without hepatocellular carcinoma (HCC) were investigated. Elevation of serum aromatic amino acids (AAA) and methionine levels observed in cirrhotic patients without malignancy was not apparent in cirrhotic cases with HCC, and thus the ratio of branched chain amino acids (BCAA) to AAA was not so diminished in the latter cases. Development of hepatic encephalopathy in cirrhotic patients with HCC led to only a slight change in the serum aminogram characteristic of hepatic failure. In patients who underwent operations, tissue amino acid compositions of hepatocellular, gastric, and colon cancers were compared with each other and their respective surrounding epithelia. Amino acid contents in the tumor tissue were generally higher than those in the respective nontumorous parts, especially in the case of HCC. The methionine, tyrosine, and phenylalanine contents in HCC were much higher than in cirrhotic or normal liver. Serum aminograms in rats with ethionine‐induced HCC were similar to those in cirrhotic patients with HCC. Amino acid contents in HCC were higher than those in the surrounding cirrhotic liver tissue of rats. Serum and liver tyrosine and isoleucine contents rose significantly in rats 5 to 6 weeks after the initiation of a 0.25% ethionine‐containing diet. After the 20th week of the experiment, by which time well‐differentiated HCC had developed, liver tyrosine and isoleucine contents increased whereas serum isoleucine concentrations decreased. The results suggest that the serum amino acid patterns characteristic of cirrhotic patients with HCC may result from the increased consumption of amino acids by HCC. Determinations of the amino acid levels are also useful for estimating the prognosis and discovering imminent hepatic encephalopathy in cirrhotic patients with HCC.

Interconvertible microheterogeneity of glucose-6-phosphate dehydrogenase in rat liver

Abstract 1. 1. Glc-6- P dehydrogenase ( d -glucose-6-phosphate: NADP + oxidoreductase, EC 1.1.1.49) specific to Glc-6- P and present in the soluble fraction of rat liver, was resolved into three major components by polyacrylamide gel disc electrophoresis. They were designated as I, II and III in order of decreasing mobility. 2. 2. Fresh liver supernatants from normal rats had only II and III while those from carbon tetrachloride-injured rats revealed all three. Aged preparations showed more of the faster moving components, and a purified preparation of the enzyme was exclusively composed of I. 3. 3. The three forms were found to be interconvertible without an appreciable change in activity. The conversion of slower into faster migrating forms was demonstrated by treatment with HgCl 2 and the reversal with β-mercaptoethanol. 4. 4. Molecular weights of these forms were found similar, and their resolution on disc electrophoresis appeared to be mainly due to charge differences.

Glutamic acid and glutamine levels in serum and cerebrospinal fluid in hepatic encephalopathy

Significant elevation of glutamic acid and glutamine concentrations in CSF was observed in hepatic encephalopathic patients with fulminant hepatitis and liver cirrhosis. However, the ratios of CSF glutamic acid to CSF glutamine levels and of CSF to serum glutamic acid and glutamine levels were significantly higher only in cirrhotic patients with hepatic encephalopathy. CSF glutamine levels were positively correlated with blood ammonia and CSF tyrosine levels in cirrhotic patients. The results indicate that CSF glutamic acid and glutamine levels are important tools in diagnosing hepatic encephalopathy in severe liver disease.

Lowering of liver acetaldehyde but not ethanol concentrations by pretreatment with taurine in ethanol-loaded rats.

A rise in blood and liver acetaldehyde concentrations following ethanol loading (1.5 g/kg b.wt) was significantly reduced when rats were pretreated orally with taurine (0.5 g/kg), a potent in vitro activator of yeast aldehyde dehydrogenase. This taurine pretreatment produced a 4-fold increase in liver taurine content.

Cathepsin B and L activities in gastric cancer tissue: correlation with histological findings

Cathepsin B and L activities in cancerous and noncancerous mucosal tissues from 29 patients with gastric cancer were determined with a small amount of tissue homogenate. Both enzyme activities were significantly higher in cancerous tissues than in noncancerous tissues. The cathepsin B activity was higher with decreasing differentiation of the cancerous tissues, and also with increasing depth of invasion and metastasis to regional lymph nodes. Significantly high cathepsin B activity was observed in specimens of poorly differentiated adenocarcinomas, as well as in specimens from patients with extensive metastasis to n2 or n3 lymph nodes. These results suggest that high cathepsin B activity is characteristic of gastric cancer which invades and metastasizes. Therefore, in cases of marked elevation of cathepsin B activity in cancerous tissues, relatively extensive resection may be necessary to obtain a cure.

MICROHETEROGENEITY OF RAT α-FETOPROTEIN*

A purified and homogeneous preparation of rat AFP, as judged by both electrophoresis on Cellogel and immunoelectrophoresis, was separated into two components, AFPa and AFPb, by disc electrophoresis on 7% polyacrylamide gel. These two components had a definite difference in electrostatic net charge and gave only a single band on SDS-electrophoresis. Immunological reactivity or electrophoretic separation or mobility of the two components could be altered by treatment with either sulfhydryl inhibitors or reducing agents but not by treatment with protein denaturants. Electrophoresis of neuraminidase-treated AFP on 5% polyacrylamide gel yielded clearly separable, slower moving four to six and finally two components depending on the time of incubation with neuraminidase. The time-dependent conversion of faster into slower migrating components of both AFPa and AFPb upon neuraminidase treatment was confirmed by reelectrophoresis of separated and similarly treated AFPa and AFPb. Two bands of sialized or desialized AFP were also observed on isoelectric focusing. Both AFPa and AFPb treated with and without neuraminidase gave single fused precipitin lines against the antiserum in Ouchterlony double-diffusion analysis. On the basis of the changes in electrophoretic mobilities of the intermediates following neuraminidase treatment, AFPa and AFPb were estimated to have at least 2.5 and 4.5 molecules of sialic acid per molecule, respectively.

DIFFERENT MECHANISMS OF INCREASED α‐FETOPROTEIN PRODUCTION IN RATS FOLLOWING CCl4 INTOXICATION AND PARTIAL HEPATECTOMY

The temporary increase in serum a-fetoprotein ( AFP) concentration during the course of hepatitis and cirrhosis of the liver in man has been suggested to be caused by liver regeneration. This suggestion is based on a similar kinetic alteration of AFP level observed in mice and rats with regenerating liver.*v2 In these experimental animals, regenerating livers have been produced by either carbon tetrachloride (CCI,) intoxication or partial hepatectomy. This complicates the interpretation of the experimental results, because CCI, poisoning causes not only regeneration but also degeneration and necrosis of hepatic cells. Our studies of key carbohydrate-metabolizing enzymes in rat livers after CCI, injury or partial hepatectomy have revealed that the extent of enzyme deviation in the injured liver is much greater than that in the liver after partial hepatectomy and that the marked enzyme alteration in the injured liver is caused by hepatic cell injury per se and is not the result of liver regeneration.3 With this view in mind, we undertook the present study to make a direct comparison of serum AFP levels following CCI, intoxication and partial hepatectomy of rats. The effects of mitomycin C and 8-azaguanine on the AFP level after these treatments were also studied to correlate the AFP production with the syntheses of DNA and RNA.

Ammonia detoxification by accelerated oxidation of branched chain amino acids in brains of acute hepatic failure rats.

BCAA aminotransferase and BCKA dehydrogenase activities are increased in the mitochondrial fractions from the brains of hepatic failure rats treated with two-thirds removal of CCl4-injured liver. Cerebral leucine decarboxylation was accelerated, and it well correlated with arterial blood ammonia levels. Elevation of brain ammonia content following an intraperitoneal injection of ammonium acetate to hepatic failure rats could be prevented by intravenous infusion of BCAA. Significantly increased brain glutamic acid, glutamine, and alanine contents were noted. These results suggested that accelerated brain BCAA catabolism in acute hepatic failure rats reduce the neurotoxicity of ammonia by promoting the synthesis of glutamic acid and glutamine from BCAA.

Quinone derivatives lower blood and liver acetaldehyde but not ethanol concentrations following ethanol loading to rats.

A rise in blood and liver acetaldehyde concentrations following an intragastric administration of ethanol to rats was significantly inhibited when the quinone derivatives 2,3-dimethoxy-5-methyl-6-decaprenyl-1,4-benzoquinone (ubidecarenone, coenzyme Q10), 4,5-dihydro-4,5-dioxo-1H-pyrrolo[2,3-f]quinoline-2,7,9-tricarboxylic acid (pyrroloquinoline quinone, PQQ) and 6-(10-hydroxydecyl)-2,3-dimethoxy-5-methyl-1,4-benzoquinone (idebenone) were injected intraperitoneally, prior to ethanol load, at a dose of 10, 11.5 and 30 mg/kg of body weight, respectively. When acetaldehyde was incubated in vitro with 1,4-benzoquinone (3.7-13.0 mM) or PQQ (1.4-4.9 mM) at 0 and 40 degrees C, the acetaldehyde concentrations slowly decreased with incubation time at 40 degrees C. The results suggest that low acetaldehyde concentrations following ethanol load are due to an accelerated oxidation of acetaldehyde by PQQ in the liver and the circulating blood.

Serum α-fetoprotein in fulminant hepatitis and hepatic regeneration following partial hepatectomy

The pleomorphism of hepatic regeneration was studied in 10 patients with fulminant hepatitis and 7 with hepatocellular carcinoma, liver cyst, and abscess who underwent partial hepatectomy. Serum AFP levels did not increase significantly following partial hepatectomy. All of four patients who survived fulminant hepatitis had high serum AFP levels with a peak either during or before hepatic encephalopathy. Serum AFP levels decreased rather gradually during the enlargement of the atrophic liver. The observations proposed two kinds of hepatic regeneration, hepatic regeneration following surgical removal of liver and repair of liver damage following virally and probably chemically induced liver deficiency.