Search PubMed⌕ Search

Biomedical subjects

C Sato

Publications and source records attributed to C Sato.

At least 199 records · Page 11Linked to original sources
PubMed1995

Effects of one-year cadmium exposure on livers and kidneys and their relation to glutathione levels.

To study the effects of a long-term cadmium exposure on livers and kidneys, rats were administered cadmium chloride (0.228 mg Cd/kg, 3 days/week ip), for one year. Significant accumulation of cadmium was observed in livers (183 +/- 40 micrograms/g liver) and kidneys (92 +/- 17 micrograms/g kidney). Serum urea nitrogen and creatinine levels were significantly elevated in the cadmium-treated rats, while liver function tests were minimally affected. Histological observations showed interstitial fibrosis with minimal cell necrosis and inflammatory cell infiltration in livers, and apparent degeneration of proximal tubules and infiltration of inflammatory cells in parenchyma of kidneys. Lipid peroxidation in livers and kidneys, as assessed by thiobarbituric acid reactive substances, revealed no differences between the cadmium-treated rats and the controls. Glutathione contents were significantly increased in the cadmium treated rats both in livers (p < 0.001), and in kidneys (p < 0.001) compared with the controls. Increased glutathione levels in livers may contribute, in part, to the prevention of serious hepatotoxicity during chronic cadmium exposure, while nephrotoxicity due to cadmium may not be prevented by glutathione.

Animals↗
PubMed1995

Aeromonas sobria infection with severe muscle degeneration in a patient with alcoholic liver cirrhosis.

A 56-yr-old male who had been followed for alcoholic liver disease was admitted for abdominal pain and a high fever. Gastrointestinal endoscopy revealed bleeding esophageal varices that were treated by endoscopic sclerotherapy. Blood culture on admission was positive for Aeromonas sobria. Then skin bullas and ulcers and severe muscle degeneration developed. The patient died despite extensive treatment with antibiotics. A. sobria infection in patients with liver cirrhosis is rare.

Aeromonas↗
PubMed1995

Effects of cadmium on glutathione metabolism in Hep G2 cells.

Effects of cadmium on hepatic glutathione (GSH) metabolism were characterized in a human-derived hepatoma cell line, Hep G2 cells. Intracellular GSH concentrations were significantly increased after incubation with cadmium at 5 and 10 microM for 24 and 48 hr. The rate of resynthesis of GSH after depleting cellular GSH by 0.5 mM of diethylmaleate was higher in cadmium (5 microM)-pretreated cells than that in untreated controls. GSH efflux from cadmium-pretreated cells was two-fold higher than that in untreated controls. On the other hand, incubation with cadmium at 5 and 10 microM for 60 min did not decrease GSH efflux. These findings suggest that increased intracellular GSH concentrations are attributed to enhanced synthesis of GSH under cadmium exposure, although the possibility of decreased intracellular consumption of GSH should further to be studied.

Animals↗
PubMed1994

Evolution and selection of hepatitis C virus variants in patients with chronic hepatitis C.

It has been shown that hepatitis C virus (HCV) populations in vivo are composed of different but highly homologous HCV genomes (quasispecies) as shown in the hypervariable region (HVR) that exists in the N-terminal of the envelope 2 gene of HCV, and that the predominant sequence of the HVR of HCV genomes changes rapidly over time. To further investigate genetic backgrounds of the change in the HVR of HCV genomes, 45 plasma samples serially obtained from nine patients with chronic hepatitis C were studied using population-based analyses. Total RNA was recovered and the envelope gene containing the HVR was amplified by the reverse transcription and nested polymerase chain reaction. The amplified cDNA was examined by the single strand conformation polymorphism (SSCP) analysis. Furthermore, 43 HCV sequences, separated by the SSCP analysis from three patients were determined by the dideoxy chain termination method, and the phylogenetic analysis was performed using the neighbor joining method. The SSCP analysis demonstrated that HCV population within each individual were composed of 1 to 6 quasispecies. These quasispecies populations in vivo changed sequentially in eight of nine patients. Gradual selections of coexisting quasispecies were observed over 6- to 18-month periods in three patients, whereas complete replacements of previous quasispecies by new quasispecies were repeatedly observed over few-month intervals in five patients. The phylogenetic analysis on these quasispecies revealed the continuous accumulation of mutations in two patients and discontinuous appearance of evolutionarily distant quasispecies in one patient. These results indicate that HCV genomes in vivo form quasispecies populations, and that these quasispecies populations change during the natural course of chronic infection. Genetic mechanisms underlining the change of the HVR of HCV genome appear to be either continuous accumulation of mutations or selective overgrowth of preexisting minor variants from the large spectrum of quasispecies populations.

Aged↗
PubMed1994

Endothelin-1 acts as an autocrine growth factor for normal human keratinocytes.

Endothelin-1 (ET-1) is an endothelium-derived 21 amino acid vasoconstrictor peptide possessing two intrachain disulfide bridges. Recently it has become evident that isoforms of ET (ET-1, -2, and -3) have a wide range of pharmacological effects in various tissues and act as autocrine/paracrine factors. We demonstrate here that ET-1 is secreted from normal human keratinocytes and may work as an autocrine growth factor through a specific receptor. In this study, human foreskin keratinocytes were cultured in serum-free MCDB 153 medium. Cell growth and [3H] thymidine incorporation in low and high Ca++ concentration media was stimulated by ET-1, -2, and -3 with similar potencies. The strongest response was observed at 10 nM ETs, whereas stimulatory activity was reduced at 100 nM. ETs suppressed keratinocyte differentiation as measured by reactivity with involucrin antibody. Plasminogen activator activity (mainly urokinase) in the medium was also stimulated by the addition of 10 nM ETs. ET-1-like immunoreactivity measured by radioimmunoassay was 1.4 fmol/day/10(6) cells in non-treated condition medium. Among the various cytokines, tumor necrosis factor-alpha (TNF-alpha), interleukin-1 alpha, and transforming growth factor-beta stimulated ET-1 secretion in a dose-dependent manner. The strongest response (ten-fold) was observed upon the addition of 10 ng/ml TNF-alpha. Scatchard plot analysis of [125I] ET-1 binding to keratinocytes revealed the presence of a single class of high affinity receptors (KD 50 pM, 9 x 10(3) sites/cell). Binding was competitively inhibited by the addition of unlabeled ET-1 and -2 with similar affinities and by ET-3 with weaker affinity. ET-1 mRNA expression in keratinocytes was detected by reverse transcription-polymerase chain reaction and was increased by treatment with 10 ng/ml TNF-alpha. These results suggest that ET-1 acts as an autocrine growth factor for keratinocytes through a specific receptor.

Base Sequence↗
PubMed1994

Sequential change of the hypervariable region of the hepatitis C virus genome in acute infection.

Hepatitis C virus (HCV) infection is characterized by persistence of liver inflammation that often leads to end-stage liver disease, although the mechanisms are not fully understood. A hypervariable region (HVR) has been reported in the E2/NS1 region of the HCV genome, in which striking diversity is found among different HCV isolates. To investigate the association of the HVR alterations with the clinical courses of HCV infection, a longitudinal analysis of the HVR in patients with acute HCV infection was carried out. Plasma samples were obtained at several times in three patients with acute hepatitis C. Plasma RNA was extracted and reverse transcribed, and DNA fragments that included the HVR were amplified by PCR. The sequences of the HVR were directly determined from the PCR products by the dideoxy chain termination method, from which amino acid sequences were deduced. In all cases, plasma HCV-RNA disappeared with the improvement of the initial alanine aminotransferase (ALT) elevation, but HCV-RNA reappeared about 1 year later with or without deterioration of the hepatitis. In a case of sporadic acute hepatitis, the HCV in the recurrent phase had seven amino acid substitutions in the HVR compared with that in the acute phase, although no amino acid changes were noted during the initial acute phase. In a case of posttransfusion hepatitis, a marked difference was observed between the acute and the recurrent phases, with an amino acid homology of 30% (8/27). The mutation rate of the HVR had a tendency to accelerate as the HCV infection progressed to the chronic stage.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1994

Mineralocorticoid type I receptor in the rat cochlea: mRNA identification by polymerase chain reaction (PCR) and in situ hybridization.

Expression of mineralocorticoid type I receptor (MR) gene in the rat cochlea was determined using molecular biological techniques. We synthesized complementary DNA (cDNA) from rat cochlear total RNA and then amplified MR cDNA fragments by polymerase chain reaction (PCR). The amplified cDNA fragments were subcloned into an expression vector and the nucleotide sequence was analyzed to confirm the expression of mRNA encoding MR in the cochlea. We then synthesized digoxigenin-labeled riboprobes with this cloned DNA template and examined the localization of MR mRNA in the cochlea by in situ hybridization. The amino acid sequence of MR cDNA expressed in the cochlea was identical to that of the MR first cloned in the rat hippocampus. In situ hybridization showed the expression of MR mRNA in marginal cells of the stria vascularis, suggesting that aldosterone may regulate microhomeostasis of the endolymph, presumably by modulating Na, K-ATPase activity. Intense MR signal was also identified in spiral ganglion cells, the function of which remains to be determined.

Aldosterone↗
PubMed1994

Hepatitis C virus after interferon treatment has the variation in the hypervariable region of envelope 2 gene.

There is a hypervariable region in the envelope 2 gene of the hepatitis C virus genome, whose heterogeneity in different hepatitis C virus isolates has been suggested to be a result of the immune selection of escape variants. To determine the role of hypervariable region variants in the mechanism of resistance to interferon observed in 75-80% of interferon-treated patients with chronic hepatitis C, hypervariable region sequences were compared before and after interferon treatment. Eight patients with chronic hepatitis C were treated with recombinant interferon-alpha-2b. DNA containing the hypervariable region was obtained by reverse transcription-polymerase chain reaction from serial plasma samples of each patient and directly sequenced without cloning to determine changes in the predominant sequence. In two patients, hepatitis C virus-RNA was eliminated by interferon treatment. In the remaining six patients, hepatitis C virus-RNA was not eradicated. The predominant hepatitis C virus which survived interferon treatment was the mutant hepatitis C virus with 3-19 out of 81 nucleotide substitutions in the hypervariable region, resulting in 2-14 out of 27 amino acid changes. Most of the nucleotide substitutions were nonsynonymous, indicating that there were positive selections for amino acid changes in the hypervariable region. The change rate was significantly higher in patients whose plasma hepatitis C virus-RNA was consistently detectable during and after interferon treatment than in patients whose plasma hepatitis C virus-RNA became undetectable during treatment and reappeared after the cessation of the treatment (4.23 +/- 0.43 vs 0.77 +/- 0.20 x 10(-1)/site/year, p < 0.01). This suggests that the evolution of the hypervariable region was associated with the effect of interferon treatment. These results suggest that hypervariable region variants play an important role in maintaining persistent infection during interferon treatment by evading host immune surveillance.

Adult↗
PubMed1994

Detection and quantification of hepatitis C virus RNA replication in the liver.

To investigate the correlation between the replication of hepatitis C virus in liver and the clinical and histopathological features, we detected and quantified plus and minus strands of HCV-RNA in plasma and in livers of patients with chronic hepatitis C by a quantitative polymerase chain reaction. RNA was extracted from the plasma and liver tissue of ten patients with biopsy-proven chronic hepatitis C. The plus and minus strands of HCV-RNA were detected by a strand-specific reverse transcription with either sense or anti-sense oligonucleotide primers deduced from the hepatitis C virus genome, and a standard HCV-RNA with an enzyme restriction site was used to quantify the amount of HCV-RNA. Both plus and minus strands of HCV-RNA were detected from the liver tissue of all patients included. The amount of plus-stranded HCV-RNA in the liver was 10 times higher than that of minus-stranded HCV-RNA. Plus-stranded HCV-RNA was detected in the plasma in all patients, while the minus strand was not detected in any patient. There was a weak correlation between the amount of both strands of HCV-RNA in the liver and that of the plus strand in plasma. There was no significant correlation between the amount of liver HCV-RNA and serum alanine transaminase and aspartate transaminase levels, or histopathological findings in the liver. The present method of detecting and quantifying liver HCV-RNA is simple and sensitive; it may be used to detect residual hepatitis C virus replication after the disappearance of plasma HCV-RNA in acute hepatitis or in chronic hepatitis after interferon treatment.

Adult↗
PubMed1994

Fluctuation of hepatitis C virus quasispecies in persistent infection and interferon treatment revealed by single-strand conformation polymorphism analysis.

Hepatitis C virus (HCV) populations in vivo consist of heterogeneous mixtures of genetically different but closely related variants defined as a 'quasispecies'. The longitudinal fluctuation of HCV quasispecies populations in chronic hepatitis C has not been elucidated. Serial plasma samples were obtained from four patients with chronic hepatitis C (two patients without any treatment and two patients treated with interferon), and cDNA fragments containing the 5'-terminal region of the E2 gene of HCV were amplified from plasma RNA using PCR. Since conventional cloning of PCR products detects only a small part of the entire population, PCR products of each sample were separated by electrophoresis using single-strand conformation polymorphism (SSCP) analysis, which can distinguish DNA fragments of the same size as different electrophoretic bands depending on their sequence-specific conformation. Separated DNA fragments were recovered from SSCP bands in gels and their nucleotide sequences determined. SSCP electrophoresis separated PCR products into bands with different mobility. Sequence analysis of these bands confirmed that HCV populations in each patient are composed of quasispecies with different E2-hypervariable regions (HVR), which are known to contain antibody epitopes. Different patterns of variation in the HVR of quasispecies were observed in individual patients with different clinical features over time during chronic infection. Following interferon treatment, some quasispecies disappeared during the treatment and reappeared after the end of the treatment, whereas other quasispecies in the same patient remained during the treatment suggesting that the sensitivity to interferon is different among quasispecies.

Base Sequence↗
PubMed1994

Focal hepatocellular necrosis and portal lymphocytic infiltration of the liver in chronic alcoholics: histopathological study of 40 liver biopsies.

Forty liver biopsies of hepatitis B surface antigen negative chronic alcoholics were histologically studied to assess the influence of hepatitis C virus (HCV)-infection. A moderate degree of focal hepatocellular necrosis and/or portal lymphocytic infiltration (FHN-PLI) was observed in 28% of the specimens, being especially prevalent in advanced cases of fibrosis and cirrhosis, and significantly correlated with HCV-infection. Eleven of these cases were examined in detail: HCV-infection was detected in eight and lymphocytic infiltration was apparent in the portal area, accompanied by formation of lymph follicles. The FHN-PLI was ascribed to alcoholic hepatitis in two HCV-negative cases and was concluded to be of unknown etiology in the remaining one HCV-negative case. This study thus indicated that over two-thirds of cases of chronic hepatitis in alcoholics can be attributed to HCV-infection, with the remainder being at least partly related to alcoholic hepatitis. The prevalence of alcohol-induced chronic hepatitis based on immunopathological findings was unclear, but was probably less frequent than previously reported.

Adult↗
PubMed1994

Phenotypic change in portal fibroblasts in biliary fibrosis.

Portal fibroblasts have been considered responsible for biliary fibrosis. Since lipocytes show differentiation toward myofibroblast-like cells in hepatic fibrogenesis, we studied whether similar differentiation of portal fibroblasts could be observed in biliary fibrosis. We examined rat livers after bile duct ligation by double immunofluorescent staining of alpha-smooth-muscle actin (alpha-smA) and desmin and also by electronmicroscopy. In the portal tract of normal livers, alpha-smA-positive cells were noted only in the vessel wall, whereas desmin-positive cells were occasionally seen in the connective tissue as well. With the development of biliary fibrosis, alpha-smA was remarkably expressed in the portal connective tissue, while desmin was seen in a small portion of alpha-smA-positive cells around proliferating bile ducts. In normal livers, portal fibroblasts presented quiescent features, such as a small Golgi complex and a few cisternal profiles of endoplasmic reticulum under electron microscopy. After 7 days of bile duct ligation, portal fibroblasts proliferated, were arrayed in multilayers, and were associated with collagen bundles. Some of these fibroblasts had numerous cytoskeletal components, and developed rough endoplasmic reticulum and a dense body. These data suggest that portal fibroblasts appear to differentiate toward myofibroblasts in biliary fibrosis.

Actins↗
PubMed1994

Isolation and characterization of a diagnostic polysaccharide antigen from larval Echinococcus multilocularis.

A diagnostic antigen, C-antigen, was evaluated in serodiagnosis of alveolar hydatid disease by Western blotting. The C-antigen migrated diffusely to the region of 30-35 kDa in 8% polyacrylamide-SDS gel electrophoresis. We isolated this antigen from a crude metacestode extract by a simple method of phenol/chloroform extraction. The isolated antigen was resistant to boiling, proteolysis and acid hydrolysis, but destroyed with sodium periodate. Such lectins as peanut agglutinin (PNA), Ricinus communis lectin (RCA120) and wheatgerm agglutinin (WGA) were capable of binding with the isolated antigen; no binding to concanavalin A (Con A), Lens culinaris agglutinin (LCA) or Phaseolus vulgaris (PHA-E4) was demonstrated. C-antigen is associated with a polysaccharide containing galactose and N-acetyl glucosamine residues.

Animals↗
PubMed1994

[Fluctuation of HCV quasi-species population during interferon therapy; analysis by single strand conformation polymorphism].

We investigated the fluctuation of hepatitis C virus (HCV) quasispecies during interferon therapy by single strand conformation polymorphism (SSCP) analysis. In 13 of 16 interferon ineffective patients, the predominant HCV population was replaced with other quasispecies during the treatment. Especially, in 9 patients, a part of the HCV quasispecies, pre-existing before interferon therapy, became predominant after the therapy. These results indicate that sensitivity to interferon differs among HCV quasispecies and that interferon selects resistant HCV strains. Existence of such HCV quasispecies seems to be associated with interferon treatment failure.

Base Sequence↗