Kazuhei Kurosawa

Transport of glutathione across the mitochondrial membranes.

Transport of glutathione (GSH) into mitochondria was observed when mitochondria in state 4 respiration were incubated with high concentrations of GSH. This transport was suppressed by antimycin A or dicyclohexyl-carbodiimide, or in state 3 respiration. Upon dissipation of the proton gradient by a proton ionophore, mitochondrial GSH was released into the medium. GSH moved freely across the proton-permeated mitochondrial membrane, its movement depending only on the GSH gradient across the inner membrane. These results indicate that there is a transport system for GSH in the mitochondrial membrane, and that a proton gradient is necessary to maintain GSH in the matrix, and to transport GSH into mitochondria.

Oxygen Supply to the Liver in Patients With Alcoholic Liver Disease Assessed by Organ-Reflectance Spectrophotometry

In the present study we have investigated hepatic hemodynamics in patients with alcoholic liver disease using reflectance spectrophotometry and the hydrogen clearance method. Analysis of 38 cases has shown that estimated regional hepatic-tissue hemoglobin concentration, expressed as a difference in absorbance between 569 and 650 nm (delta Er569-650), decreased significantly with progress of fibrosis or fat accumulation in the liver. This suggests that the relative compression of the vascular compartment is due to the progress of alcoholic liver disease. Estimated hepatic hemoglobin concentration also correlated positively with prothrombin time, and negatively with serum gamma-globulin level and 15-min retention rate of indocyanine green. The difference in absorbance between 569 and 650 nm obtained by reflectance spectrophotometry was positively correlated with the regional hepatic blood flow as measured by the hydrogen clearance method. Thus, it is concluded that the estimated regional hepatic-tissue hemoglobin concentration decreases with progress of fibrosis and fat accumulation in the liver, and that this decreased oxygen supply to the liver may have an important role in the progress of alcoholic liver disease.

Thrombotic thrombocytopenic purpura developed suddenly during interferon treatment for chronic hepatitis C

Abstract: A 57-year-old man had abnormal hepatic function identified in April 1994. In October 1994, chronic hepatitis C was diagnosed. Based on the findings of a liver biopsy, administration of recombinant interferon (rIFN)-α2b was begun. In the 16th week of treatment, the patient experienced headache and fever and developed a markedly decreased, platelet count and hemolytic anemia. He was admitted on May 19, 1995 and thrombotic thrombocytopenic purpura (TTP) was diagnosed. He died on the 3rd hospital day. The causes of TTP have yet to be elucidated, but in this patient the occurrence of TTP appeared to be related to the IFN treatment for chronic hepatitis C.

Ca2+-induced, phospholipase-independent injury during reoxygenation of anoxic mitochondria

Reoxygenation of rat-liver mitochondria after anoxic incubation induced release of matrix proteins. As assessed by release of a matrix enzyme, it was proportional to the rate of H2O2 production. The release was not observed with low concentrations of extramitochondrial free Ca2+, indicating a Ca(2+)-dependent pathway. Phospholipase A2 was not involved in the reoxygenation injury, because non-esterified fatty acids did not increase on reoxygenation even when re-acylation was inhibited and because inhibitors of phospholipase A2 had little effect on enzyme release. Cyclosporin A, ATP, ADP and inhibitors of pyridine nucleotide oxidation had a protective effect, strongly suggesting involvement of so-called Ca(2+)-dependent permeability transition. Ca2+ was also released from reoxygenated mitochondria and inhibition of reuptake of released Ca2+ attenuated the enzyme release. Similar releases of aspartate aminotransferase and Ca2+ were observed with mitochondria in an oxygen radical-generating system, hypoxanthine and xanthine oxidase. In this system, lecithin-cardiolipin liposomes also released entrapped Ca2+ without disruption of the membrane. From these results, we conclude that during reoxygenation, Ca2+ release and subsequent reuptake induced permeability transition of mitochondria, resulting in reoxygenation injury.

Protection of cellular and mitochondrial functions against anoxic damage by fructose in perfused liver

In anoxic perfused liver, conversion of fructose to lactate was greatly increased to about 3 mumol/min per g liver. This increase in lactate implied that the same amount of ATP was also produced. The rate of metabolism of glucose was less than 10% of that of fructose, as judged by rate of production of lactate. In anoxic liver perfused with fructose, the ATP levels of both the tissue and mitochondria remained high, despite lack of oxygen, thus preventing enzyme leakage and preserving processes requiring ATP, such as bile excretion and urea formation. The mitochondrial oxidative phosphorylation capacity of anoxic liver perfused with fructose was also unimpaired. Spectral analysis of light transmitted through the liver revealed that the mitochondrial electron transfer system was in the completely reduced state during anoxia, indicating that the mitochondria were incapable of synthesizing ATP. These results suggest that fructose metabolism during anoxia resulted in sufficient production of ATP for maintaining the physiological functions of the cells and the oxidative phosphorylation capacity of their mitochondria.

ENDOSCOPIC FOLLOW-UP STUDY OF DEVELOPMENT OF GASTRIC ANTRAL VASCULAR ECTASIA ASSOCIATED WITH LIVER CIRRHOSIS

Gastric antral vascular ectasia is an important cause of chronic gastrointestinal blood loss. However, its development and progression have not yet been clarified. We investigated its early lesions and progression by reviewing endoscopic films of five patients with gastric antral vascular ectasia followed for liver cirrhosis. In all patients, early findings were prepyloric red spots. In two patients, anemia due to gastrointestinal bleeding was already observed when vascular lesions were confined to the distal antrum. In the other three patients, anemia was observed 1–2 years after they showed a diagnostic pattern of gastric antral vascular ectasia. The vascular lesions gradually thickned and extended throughout the antrum, with the complete picture shown in 1.5–5 years. The pattern of distribution was classified into three types: diffuse spotty, diffuse confluent, and striped. These types could be predicted before the complete formation. Gastric antral vascular ectasia associated with liver cirrhosis started as prepyloric red spots and extended to the proximal antrum in various ways and varying time courses of less than 5 years; this entity may cause hemorrhage even in the early stage.

An assay method for cyclic AMP using high-performance liquid chromatography with pretreatment by alkaline phosphatase☆

A convenient method for determination of cyclic AMP is described. This nucleotide was determined using high-performance liquid chromatography after the treatment of tissue extracts by alkaline phosphatase. Tissue extracts contain large amounts of materials which interfere with the measurement of cyclic AMP on the chromatogram. By the alkaline phosphatase treatment, these materials were completely converted to compounds which no longer interfered with the measurement. This method enables the detection of 2 pmol cyclic AMP, and is applicable to various tissue extracts which contain at least 0.1 nmol cyclic AMP/g wet wt.

Hepatic hemodynamics in alcoholic liver injuries assessed by reflectance spectrophotometry.

We have investigated the hepatic hemodynamics by reflectance spectrophotometry in patients with alcoholic liver disease. The analysis of 32 cases has shown that the estimated regional hepatic tissue blood hemoglobin concentration, expressed as a difference in absorbance between 569 and 650 nm (delta Er569-650), decreased significantly with progress of fibrosis in the liver, suggesting the relative compression of the vascular compartment due to the progress of alcoholic liver disease. The estimated hepatic oxygen consumption also decreased with progress of fibrosis in the liver. The estimated hepatic oxygen consumption correlated positively with prothrombin time and serum albumin level, and negatively with the fifteen minute retention rate of indocyanine green. Thus, it is concluded that the imbalance between supply and utilization of oxygen in the liver may have an important role in the progress of alcoholic liver disease.

Retreatment with interferon for chronic hepatitis C after transient response.

Approximately half of all patients with chronic hepatitis C show an initial biochemical response to interferon, but only 15% to 20% of patients achieve a sustained response. We studied the efficacy of retreatment with interferon for patients with chronic hepatitis C who showed transient biochemical responses to initial treatment. Thirty patients who relapsed were retreated 1 to 52 months (median 14) after the end of initial treatment, according to the previously used regimens. The responses were correlated with the pre-retreatment patient data. The liver histologic grades, compared with those found before the initial treatment, were better in eight (27%) patients but worse in six (20%), whereas the fibrosis stage was improved in five (17%) but worsened in eight (27%). All patients displayed end-of-retreatment biochemical responses. Of the 30 patients, 10 (33%) achieved sustained aminotransferase normalization and serum hepatitis C virus (HCV) RNA clearance, but the remaining 20 patients showed relapse within 1 year after cessation of retreatment. Univariate analysis associated the sustained response with low pre-retreatment viral loads (0.8 ± 0.7 MEq/mL vs. 9.1 ± 6.5 MEq/mL;p = 0.006), short treatment intervals (13 ± 13 months vs. 22 ± 14 months;p = 0.031), and low histologic grades (1.3 ± 0.7 vs. 1.9 ± 0.7;p = 0.039). However, multivariate analysis indicated that only the pre-retreatment viral load was predictive of the sustained response (p = 0.049). These findings suggest that transient responders to interferon are likely to respond to retreatment but the achievement of a sustained response depends on the HCV viral load before retreatment.

Delivery and Use of Oxygen in the Hepatic Tissue Assessed by Organ-Reflectance Spectrophotometry

Although the importance of oxygen in maintaining functional and morphological integrity of the liver is well established in the experimental animal, little is known about the oxygen supply and utilization in the liver in patients with chronic liver diseases. We have recently developed a spectrophotometric method to estimate the concentration of hemoglobin in the hepatic tissue, the oxygen saturation of hemoglobin in the regional blood, and the hepatic oxygen consumption. In this study, to clarify whether the balance between delivery and use of oxygen in the hepatic tissue is disturbed in chronic liver disease, we investigated hepatic hemodynamics in patients with chronic liver diseases using reflectance spectrophotometry.