The hypervariable region of the HCV genome changes sequentially during the progression of acute HCV infection to chronic hepatitis.
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Acute Disease↗
Biomedical subjects
C Sato
Publications and source records attributed to C Sato.
Detection of hepatitis C viral RNA in sporadic acute non-A, non-B hepatitis by polymerase chain reaction. Its usefulness for the early diagnosis of seronegative infection.
To determine the prevalence of hepatitis C viral infection in patients with sporadic non-A, non-B (NANB) acute hepatitis, hepatitis C viral RNA was studied in the plasma of 15 patients by reverse transcription-polymerase chain reaction assay. Plasma samples were sequentially obtained from 15 patients, and polymerase chain reaction was performed with two nested pairs of primers deduced from the 5'-non-coding region of hepatitis C viral sequences. Anti-C100 and anti-GOR antibodies were also measured with an enzyme-linked immunosorbent assay system. Plasma hepatitis C viral RNA was detected transiently in 7 of 15 patients (47%) at an early phase of the clinical course, while anti-C100 antibodies were detectable in only 2 (29%) of hepatitis C viral RNA-positive patients, and in 1 (13%) of the negative patients. Of 7 patients that were positive for plasma hepatitis C viral RNA, 4 (57%) had relapsing or protracted courses. In contrast, in all patients with undetectable hepatitis C viral RNA, hepatitis C viral RNA recovered and remained normal for at least 1 year. Thus, hepatitis C viral infection represents almost half the patients with acute sporadic NANB hepatitis, and detection of hepatitis C viral RNA in an early clinical phase is superior to anti-C100 measurement for diagnosing acute sporadic hepatitis C viral infection.
Adult↗
Hepatitis C virus infection in alcoholic liver cirrhosis in Japan: its contribution to the development of hepatocellular carcinoma.
To determine risk factors for hepatocellular carcinoma (HCC) in Japan, we studied 575 patients with liver cirrhosis (LC) who presented to our out-patient clinics in a month; 217 patients with habitual drinking with or without viral infections (AL-LC), 235 with hepatitis C virus (HCV) infection, 40 with hepatitis B virus (HB) infection, and 82 with liver diseases from other aetiologies such as primary biliary cirrhosis (PBC). HCC was found in 28% of AL-LC, 27% of HCV-LC, and 18% of HB-LC. HCV antibody examined by the second-generation HCV antibody assay (HCV II) was positive in 49% of AL-LC without HCC, and 84% of AL-LC with HCC. HCV was significantly associated with the development of HCC with an odds ratio of 1.90 by multivariate analysis, whereas alcohol alone did not become a risk factor, with an odds ratio of 0.65. When both variables were combined (HCV+AL), however, the odds ratio was increased twice to 3.65. One-hundred and thirteen patients who had a history of blood transfusion more than 10 years ago were selected to assess the interaction between alcohol and HCV in hepatocarcinogenesis. A year-adjusted disease occurrence rate calculated by the Kaplan-Meyer method showed that HCV+AL had a significantly higher disease occurrence rate than HCV alone. These results suggest that although alcohol alone may not become a risk factor for HCC, it may potentiate the development of HCC caused by HCV. HCV+AL is considered to be the highest risk group; strict abstinence is necessary for these patients.
Adult↗
Keratinocyte growth factor (FGF-7) stimulates migration and plasminogen activator activity of normal human keratinocytes.
Keratinocyte growth factor (KGF), a member of the fibroblast growth factor (FGF) family (and alternatively designated FGF-7), is a paracrine growth factor produced by mesenchymal cells and mitogenic specifically for epithelial cells. The potential effect of KGF on wound healing was assessed in vitro by measuring randomized migration and plasminogen activator (PA) activity of keratinocytes in response to the growth factor. Incubation of normal human keratinocytes with KGF in modified MCDB 153 medium significantly stimulated cell migration and PA activity compared with control (p < 0.001 and p < 0.01, respectively). When tested in these assays on an equimolar basis, 1 nM KGF was at least as potent as transforming growth factor alpha and more active than basic FGF. None of these effects were observed when KGF was administered to fibroblasts or endothelial cells. Stimulation of keratinocyte migration by KGF was dose dependent, and a neutralizing monoclonal antibody against KGF reduced KGF-stimulated migration and cell growth. Zymographic analyses of cell extracts and conditioned medium from KGF-treated keratinocytes revealed increased PA activity, which was mainly attributable to an elevated level of urokinase-type PA. These in vitro results suggest that KGF may have an important role in stimulating reepithelialization during the process of wound repair.
Cell Movement↗
Genetic changes and histopathological grades in human hepatocellular carcinomas.
Loss of heterozygosity (LOH) on chromosomes 1p, 4q, 5q, 8p, 13q, 16q, 17p, and 22q, and mutation of the p53 gene were simultaneously analyzed in 63 hepatocellular carcinomas (HCCs) with distinct histopathological grades, 80% of the tumors being from patients who had been exposed to hepatitis B virus (HBV) or hepatitis C virus (HCV). The frequencies of LOH on 8 chromosomes were 0-25% in 10 well differentiated HCCs, LOH being observed on 4q, 5q and 17p, 21-53% in 26 moderately differentiated HCCs, LOH on 8p and 17p being high, and 29-75% in 27 poorly differentiated HCCs, LOH on 17p, 4q and 8p being the most frequent. p53 gene mutation was detected in moderately and poorly differentiated HCCs at 15% and 52%, respectively, but not at all in well differentiated HCCs. Of the mutations detected, 42% were transition mutation and only 5% were CpG transition, in contrast to the high frequencies of these types of mutations in colon tumors (78% and 54%, respectively). LOH on every chromosome and p53 mutation were more frequent in more advanced tumors, and accumulation of genetic changes increased with increase of the histopathological grade. Frequency of genetic changes in HCCs from HBV-positive patients was comparable to that from HCV-positive patients. The present results suggest that accumulation of genetic changes in multiple tumor suppressor genes, especially LOH on 17p, 4q and 8p, and mutation in p53 gene, are involved in the progression of liver cancer, and LOH on 17p and 4q precedes other genetic changes. Differences in the direction of p53 mutation between HCC and colon carcinoma suggest that liver carcinogens are distinct from colon carcinogens. Furthermore, mechanisms affecting the frequency of LOH in HCCs in HBV-infected patients may be similar to those in HCV-infected patients.
Base Sequence↗
Detection of hepatitis C virus RNA in the liver by in situ hybridization.
To examine HCV infection histologically, we attempted non-radioactive in situ hybridization of HCV-RNA in the liver. We amplified cDNA probe (360 base pairs) by PCR using the primers deduced from the core region of the HCV genome. The probe was labelled with digoxigenin by PCR and used for in situ hybridization on paraformaldehyde-fixed frozen liver sections. The hybrids were visualized immunohistochemically with alkaline-phosphatase-conjugated anti-digoxigenin and alkaline-phosphatase substrates. HCV-RNA-cDNA hybrids were detected in 21 of 24 patients with positive serum HCV markers, whereas there were no positive signals in the liver of 12 cases without HCV infection. The signal intensity of HCV-RNA-cDNA hybrids was abolished after RNase treatment. Various other specificity experiments also verified specific hybridization of HCV-RNA-cDNA. HCV-RNA was visualized in liver cells and most of them were regarded as hepatocytes from their characteristic features. The infected hepatocytes were frequently associated with mononuclear cell infiltration. Hepatocytes positive for HCV-RNA were sometimes binuclear and distributed in various patterns among cases tested. The present in situ hybridization of HCV RNA is highly sensitive and specific and the results suggest the host immune response to HCV-infected cells.
Hepacivirus↗
Role of hepatic vitamin A and lipocyte distribution in experimental hepatic fibrosis.
Lipocytes are the major site of hepatic vitamin A storage, and they have been demonstrated to lose their vitamin A content in the process of hepatic fibrosis. To investigate the relationship between hepatic vitamin A content and the degree of hepatic fibrosis, we measured levels of retinyl palmitate and retinol in the CCl4-induced fibrotic liver using high-performance liquid chromatography. We estimated hepatic collagen content using a spectrophotometric analysis with sirius red, and also by measuring hydroxyproline levels. Lipocytes were detected by an immunoperoxidase method with anti-desmin antibody, and were counted morphometrically through a Texture Analyzing System. A significant negative correlation was observed between the level of retinyl palmitate and collagen content (r = -0.64) as well as the hydroxyproline level (r = -0.69) in the CCl4-induced fibrotic liver. In the process of fibrosis, hepatic retinol levels were elevated in association with a decrease in retinyl palmitate. In particular in the early stage of fibrosis, lipocytes increased remarkably in number in fibrotic areas in spite of a decrease in total hepatic vitamin A. The present study suggests that an increase in hepatic retinol as well as a decrease in retinyl palmitate may facilitate the process of hepatic fibrosis produced by lipocytes.
Animals↗
Rapid sequence variation of the hypervariable region of hepatitis C virus during the course of chronic infection.
To evaluate the clinical significance of sequence variations in the hypervariable region of hepatitis C virus during the course of chronic infection, we performed pairwise comparison of the predominant nucleotide sequences. Hepatitis C virus RNA was extracted from two plasma samples obtained from 12 chronically infected Japanese patients over approximately 1 yr. Complementary DNA containing the hypervariable region was amplified by means of reverse transcription-polymerase chain reaction and was directly sequenced for determination of predominant sequences. In all 12 individuals, the predominant sequence of the hypervariable region at the second time point differed from that at the first time point, and significant sequence variation was observed during this short period. A high proportion of these nucleotide substitutions (90%) resulted in changes of predicted amino acid sequences, indirect evidence of in vivo positive selection for these variants. There appeared to be an important difference in the rate of nucleotide sequence variation of the hypervariable region between four patients with flare-ups of their ALT levels (1.54 to 2.24 x 10(-1)/genome site/yr) and eight patients with quiescent courses (0.13 to 1.21 x 10(-1)/genome site/yr). These results demonstrate that rapid sequence variations of the hypervariable region of predominant virus population take place during the natural course of chronic hepatitis C virus infection. These sequence variations seem to occur as an adaptive response of hepatitis C virus to evade host immunity and may play a major role in the establishment of persistent infection and in the occasional flare-up of hepatitis.
Aged↗
Adenosine deaminase isoenzymes in liver disease.
To clarify the clinical significance of increased serum adenosine deaminase (ADA) activity, and its mechanisms in various liver diseases, ADA isoenzyme activities (ADA1 and ADA2) in serum and the peripheral blood mononuclear cells were studied. High serum ADA activities were found in patients with acute hepatitis, alcoholic hepatic fibrosis, chronic active hepatitis, liver cirrhosis, and hepatoma. The ADA2:ADA ratio was decreased in acute hepatitis, but was increased in chronic active hepatitis and liver cirrhosis. Clinically, ADA2 activity was correlated with serum gamma-globulin levels. In chronic active hepatitis, total ADA activities in the peripheral blood mononuclear cells were similar to those in controls. Furthermore, ADA2 activities after phytohemagglutinin (PHA) stimulation were significantly lower than those without PHA stimulation, although total ADA activities were increased after PHA stimulation. These findings suggest that serum ADA isoenzyme activities may be a new marker for liver disease, and that the increased serum ADA2 in chronic active hepatitis is unlikely to be the result of an increase in ADA2 production by activated peripheral blood mononuclear cells.
Adenosine Deaminase↗
Leiomyoma of the common bile duct.
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Cholestasis↗
Proposed tertiary structure of the sodium channel.
On the basis of our recent results of the complete amino acid sequence of the squid Loligo bleekeri sodium channel deduced by cloning and sequence analysis of the complementary DNA (Sato, C. and Matsumoto, G. Biochem. Biophys. Res. Comm. 186, 1), we have proposed a tertiary structure model of the sodium channel where the transmembrane segments are octagonally aligned and the four linkers of S5-6 between segments S5 and S6 play a crucial role in the activation gate, voltage sensor and ion selective pore, which can slide, depending on membrane potentials, along inner walls consisting of segments S2 and S4 alternately. The proposed model is contrasted with that of Noda et al. (Nature 320; 188-192, 1986).
Amino Acid Sequence↗
Primary structure of squid sodium channel deduced from the complementary DNA sequence.
The complete amino acid sequence of a sodium channel from squid Loligo bleekeri has been deduced by cloning and sequence analysis of the complementary DNA. The deduced sequence revealed an organization virtually identical to the vertebrate sodium channel proteins; four homologous domains containing all six membrane-spanning structures are repeated in tandem with connecting linkers of various sizes. A unique feature of the squid Na channel is the 1,522 residue sequence, approximately three fourths of those of the rat sodium channels I, II and III.
Amino Acid Sequence↗
c-myc expression is down-regulated by cell-cell and cell-extracellular matrix contacts in normal hepatocytes, but not in hepatoma cells.
Primary culture of adult rat hepatocytes resulted in marked increase of c-myc expression within a few hours. The high level of c-myc mRNA was maintained throughout culture on collagen-coated dishes, but decreased greatly with time during culture on collagen-gel or matrigel. Expression of c-myc was also down-regulated at high cell density. The decrease in its expression appeared closely related to inhibitions of DNA synthesis and cell spreading. In contrast, hepatoma H4TG cells showed a high level of c-myc expression which was not affected by culture on any extracellular matrices examined or by the cell density. These results suggest that up-regulation of expression of the c-myc gene is linked to G0 to G1 transition during cell cycle progression, which in normal hepatocytes is strictly regulated by cell-cell and cell-extracellular matrix interactions, but that this control mechanism is defective in malignant hepatic tumor cells.
Animals↗
Clinical significance of elevated plasma endothelin concentration in patients with cirrhosis.
Endothelin is a newly discovered potent vasoconstrictor peptide. To explain the clinical significance of endothelin in patients with chronic liver diseases, we measured the plasma concentration of endothelin in patients with chronic hepatitis (n = 15), cirrhosis with ascites (n = 8) and cirrhosis without ascites (n = 12), and we compared the findings with the plasma concentration of endothelin in normal controls (n = 14). The plasma endothelin concentration was significantly higher in patients with cirrhosis with ascites than in normal controls (8.3 +/- 2.3 pg/ml vs. 3.3 +/- 1.4 pg/ml, mean +/- S.D., p less than 0.001), whereas no significant difference was observed between normal controls and the other groups of patients (cirrhosis without ascites = 5.0 +/- 1.3 pg/ml; chronic hepatitis = 3.8 +/- 1.2 pg/ml). In patients with cirrhosis, the plasma endothelin concentration showed a significant negative correlation with creatinine clearance (r = -0.73, p less than 0.01), but no significant correlation was observed between plasma endothelin concentration and fractional excretion of filtered sodium. Furthermore, plasma endothelin levels were significantly higher in patients with endotoxemia than in those without (10.1 +/- 2.1 pg/ml vs. 4.9 +/- 1.2 pg/ml, p less than 0.001). From these results, elevated plasma endothelin, which has a close relation to endotoxemia, may play a contributory role in kidney dysfunction in patients with cirrhosis.
Aldosterone↗
V1-receptor mediated GSH efflux by vasopressin from rat hepatocytes.
Vasopression increases sinusoidal efflux of GSH in the perfused rat liver. The mechanism of this effect was studied in the perfused rat liver and in isolated rat hepatocytes. Vasopressin stimulated GSH efflux in both systems and a V1-receptor antagonist (OPC-21268) significantly inhibited the effect of vasopressin suggesting that vasopressin stimulates GSH efflux from rat hepatocytes via V1-receptor.
Angiotensin Receptor Antagonists↗
Possible involvement of protein kinase C and calcium in GSH efflux from Hep G2 cells.
We investigated the effects of protein kinase C modulations and calcium mobilization on GSH efflux in Hep G2 cells. GSH efflux from Hep G2 cells was increased by a phorbol ester. Staurosporine, an inhibitor of protein kinase C, diminished phorbol ester-stimulated GSH efflux from the cells. GSH efflux was negatively correlated with extracellular calcium concentrations. Verapamil enhanced GSH efflux, whereas ATP decreased GSH efflux. The latter effect was diminished in the absence of extracellular calcium. Protein kinase C and calcium mobilization may be crucial factors in GSH efflux from human hepatocytes.
Adenosine Triphosphate↗
Radiosensitization by 2-nitroimidazole nucleoside analog RP-170: radiosensitizing effects under both intravenous and oral administration.
The radiosensitizing activity, pharmacokinetics and toxicity of RP-170, 2-nitroimidazole nucleoside analog, were investigated and compared with those of etanidazole (SR-2508). An intravenous administration (i.v.) of 100 mg/kg of RP-170 or the same dose of etanidazole showed an equal sensitizer enhancement ratio (SER) of about 1.4 to solid EMT6 tumor under in vivo-in vitro assay and a virtually equal SER of 1.4-1.5 to solid SCC VII tumor under tumor growth delay assay. As predicted from the low partition coefficient, lower drug levels in neural tissue and more rapid serum elimination of RP-170 and etanidazole produced lower acute toxicity than lipophilic sensitizers (e.g., misonidazole). The major advantage of RP-170 over etanidazole is that it has a second route of administration. In contrast to etanidazole, in which the administration route is limited to intravenous injection, with RP-170 oral administration also exhibited effective distribution to tumors, sensitizing radiation activity to solid EMT6 and SCC VII tumors. Moreover, LD50 in mice of RP-170 (4.3 g/kg on i.v.) was increased to 5.2 g/kg by oral administration. This availability of two routes of administration indicates RP-170 as a promising hypoxic cell radiosensitizer for clinical use.
Administration, Oral↗
Inhibition of acetaminophen hepatotoxicity by acetaldehyde in the rat.
Since we have observed that acetaldehyde, an oxidative metabolite of ethanol, inhibits acetaminophen activation in rat liver microsomes, the in vivo effect of acetaldehyde on acetaminophen hepatotoxicity was tested. In vivo experiments in 3-methylcholanthrene-pretreated male Sprague-Dawley rats showed that administration of cyanamide (20 mg/kg, i.p.) and acetaldehyde (600 mg/kg, s.c.) given 3 and 1 h, respectively, prior to acetaminophen (500 mg/kg, i.p.) but not cyanamide alone prevented acetaminophen hepatotoxicity as assessed by serum transaminases and histology. Acetaldehyde may partly be responsible for the inhibitory effect of ethanol on acetaminophen hepatotoxicity.
Acetaldehyde↗