Biomedical subjects

C Sato

Publications and source records attributed to C Sato.

At least 163 records · Page 9Linked to original sources

PubMed1995

Detection of hepatitis C virus RNA in hepatocellular carcinoma by in situ hybridization.

BACKGROUND: Hepatocellular carcinoma frequently is associated with chronic hepatitis C virus (HCV) infection. The presence of HCV in hepatocellular carcinoma has been detected by reverse-transcription polymerase chain reaction of antigenomic HCV RNA, a tissue-specific replicative form of the virus. Now, however, this method of detecting the presence of HCV has been invalidated by reports of antigenomic RNA in the blood or in peripheral blood mononuclear cells. METHODS: In situ hybridization of HCV RNA was conducted with digoxigenin-labeled cDNA from the core region on surgical specimens of noncancerous and cancerous areas from 12 patients with chronic hepatitis C with or without cirrhosis associated with hepatocellular carcinoma. Several control experiments were also performed, including RNase digestion before hybridization, hybridization with the use of a negative control, and immunohistochemical staining of HCV-core protein. RESULTS: The in situ hybridization showed positive signals both in noncancerous and cancerous areas of the liver tissue in eight cases. Positive signals were confined to neoplastic cells and nonneoplastic hepatocytes. There were fewer HCV-positive cells in the cancerous area than in the surrounding noncancerous area. CONCLUSIONS: In situ detection of HCV presents direct evidence of HCV infection in the neoplastic cells of hepatocellular carcinoma and suggests that neoplastic cells may lose their affinity for HCV in the course of malignant transformation.

Carcinoma, Hepatocellular↗

PubMed1995

Ultraviolet B irradiation increases endothelin-1 and endothelin receptor expression in cultured human keratinocytes.

The effect of ultraviolet B (UVB) irradiation on endothelin-1 (ET-1) and ET receptor expression was examined using cultured normal human keratinocytes. Keratinocytes secreted ET-1 in the medium at a level of 2.1 pg/day/10(5) cells. UVB irradiation up to 10 mJ/cm2 increased ET-1 secretion 3-fold, and potentiated expression of mRNA for ET-1. Both ETA and ETB receptor mRNAs were detected in keratinocytes, and their expression was up-regulated by 5 mJ/cm2 UVB irradiation.

Base Sequence↗

PubMed1995

Possible neuronal origin of ATP release evoked by forskolin and ouabain from guinea-pig atrial segments.

The characteristics of ATP release evoked by forskolin and ouabain from atrial segments of guinea-pig were evaluated under electrical stimulation. Forskolin (1 microM) produced a massive release of ATP together with a positive inotropic response. Both 30 microM W-7 (N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide.HCI), a calmodulin antagonist, and 30 microM vinblastine, a mitotic inhibitor, markedly inhibited the evoked release of ATP without affecting the evoked contraction. However, 100 microM N-ethylmaleimide abolished completely the basal and drug-evoked ATP release and further the evoked contraction. Both the ATP release and contraction evoked by ouabain (3 microM) were similarly affected by W-7, vinblastine and n-ethylmaleimide. The release of ATP, but not the contraction, evoked by forskolin was strongly suppressed by 10 microM okadaic acid, a protein phosphatase inhibitor. The suppression by okadaic acid of the evoked release was thoroughly antagonized in the presence of 0.01 microM PMA (phorbol 12-myristate 13-acetate), but not 10 microM H-7 (1-(5-isoquinolinesulfonyl)-2-methylpiperazine). These results suggest that forskolin, like ouabain, may dominantly cause the neuronal release of ATP from cardiac adrenergic nerves, although the possible participation of release from muscular sources cannot be ignored.

Adenosine Triphosphate↗

PubMed1995

Characterization of the antigenic specificity of four different anti-(alpha 2-->8-linked polysialic acid) antibodies using lipid-conjugated oligo/polysialic acids.

A rapid, sensitive, and facile method for screening and characterizing anti-polysialic acid (polySia) antibodies using lipid-conjugated oligo/polysialic acids (oligo/polySia) was developed, which is based on an enzyme-linked immunosorbent assay. Homooligo/polymers of alpha 2-->8-linked N-acetylneuraminic acid (Neu5Ac), N-glycoly-neuraminic acid, and 2-keto-3-deoxy-D-galacto-nononic acid (KDN) were conjugated with phosphatidylethanolamine dipalmitoyl (PE) by reductive amination to prepare neo-oligo/polysialoglycolipids (oligo/polySia-PE). Using this method, the anti-polySia equine antibody, H.46, bound to (-->8Neu5Ac alpha 2-->)n-PE, where n = 9 or more residues, a result in confirmation of previous binding studies using radiolabeled oligo/polyNeu5Ac. The antigenic specificity and sensitivity of two monoclonal anti-poly/oligoNeu5Ac antibodies (mAb.12E3 and mAb.5A5) and one anti-oligoKDN antibody (mAb.kdn8kdn), were also determined. mAb.12E3 could detect as little as 25 pg/well of oligo/polyNeu5Ac-PE, while 0.4 ng/well of oligo/polyNeu5Ac-PE to be detected. mAb.kdn8kdn detected as little as 12 ng/well of oligoKDN-PE. Using a series of oligo/polySia-PE with defined degrees of polymerization (DP), the minimum chain length for immunoreactivity of the anti-polySia antibodies was determined to be: DP 5 for mAb.12E3; DP 3 for mAb.5A5; DP 2 for mAb.kdn8kdn; and DP 8 for H.46. Thus, mAb.12E3 and mAb.5A5 recognize shorter oligomers of Neu5Ac than H.46, a finding that is of practical value for identifying shorter oligoSia chains in glycoconjugates. Because mAb.12E3 and mAb.5A5 also recognize extended polySia chains, these antibodies cannot be used, however, to differentiate between short and long chains of polySia when both are expressed on the same molecule.

Animals↗

PubMed1995

Detection of Helicobacter pylori infection in early stage gastric cancer. A comparison between intestinal- and diffuse-type gastric adenocarcinomas.

BACKGROUND: Helicobacter pylori (H pylori) infection has been suggested to be a risk factor for gastric carcinogenesis. However, those previous studies have been concerned with advanced cancer cases. To the authors' knowledge, no detailed investigation on the prevalence of H pylori in early stage gastric cancer tissue has been performed. The relationship between early stage gastric cancer and the prevalence of H pylori was studied by a immunohistochemical staining analysis. METHODS: Sixty-eight patients who were endoscopically and surgically diagnosed as having early stage gastric cancer were enrolled in this study. All tissue specimens were obtained from patients by endoscopic biopsy, and were classified histopathologically as the intestinal-type of early stage gastric cancer in 34 patients (male-to-female ratio, 28:6; age, 64 +/- 11 years) and the diffuse-type of early stage gastric cancer (male-to-female ratio, 23:11; age, 57 +/- 14 years) in the other 34 patients. The amount of H pylori in tissue samples was graded from 0 (no characteristic bacteria) to 3 (numerous bacteria) using the fluorescent microscopic and an immunohistochemical technique. RESULTS: Twenty-nine of the 34 cases of the intestinal-type of gastric cancer had H pylori infection, as compared with 11 of the 34 cases of diffuse-type early stage gastric cancer. A significantly higher incidence (85%; P < 0.001) of H pylori infection and, thus, higher grading scores of the number of H pylori were found in the intestinal-type early stage gastric cancer. CONCLUSIONS: These findings suggest that the infection of H pylori may have a crucial relationship to the early stages of carcinogenesis of intestinal-type gastric cancer.

Adenocarcinoma↗

PubMed1995

ATP release evoked by isoprenaline from adrenergic nerves of guinea pig atrium.

Mode and site of release of ATP evoked by isoprenaline were evaluated in the electrically driven left atrial segment of guinea pig. The peak release of ATP 5 min after 1 microM isoprenaline was inhibited by 1 microM propranolol and 1 microM butoxamine, but not by 1 microM atenolol, showing that the ATP release is due to stimulation of the presynaptic beta 2-adrenoceptor by isoprenaline. The maximum ATP release was markedly reduced by Ca2+/calmodulin antagonists, W-7 and trifluoperazine, and by a mitotic inhibitor, vinblastine. Further, the release was similarly inhibited by myosin light chain kinase inhibitors, ML-7 and wortmannin. Nifedipine, a Ca(2+)-channel blocker, decreased the release of ATP evoked by isoprenaline. By contrast, Bay K 8644, a Ca(2+)-channel opener, tended to enhance the ATP release. These findings suggest that isoprenaline produces ATP release from adrenergic nerve terminals of atrium, implying that ATP serves as a co-transmitter.

Adenosine Triphosphate↗

PubMed1995

Neuronal specificity of subtype SQSC1 of squid putative sodium channel.

The distribution of SQSC1 mRNA in tissues of squid Loligo bleekeri was studied by the blot hybridization method. The complete cDNA for the coding region of SQSC1, the invertebrate putative sodium channel, was prepared from squid optic lobe (Sato and Matsumoto, Biochem. Biophys. Res. Comm. 186, 61-68, 1992). Transcriptional products of the SQSC1 gene were found to consist of two main different lengths (12 and 9 kb). The transcriptional products were detected in all the nervous tissues examined: optic lobes, cerebral ganglia and giant stellate ganglia. However, it was not detected in the muscle, suggesting the SQSC1 gene is specific for sodium channels of squid nerve cells. SQSC1 appears more widely distributed in the nervous system than GFLN1 which they reported as expressed specifically in stellate ganglion of the squid (Rosenthal and Gilly, Proc. Natl. Acad. Sci. USA 90, 10026-10030, 1993).

Alternative Splicing↗

PubMed1995

Comparison of the hypervariable region of hepatitis C virus genomes in plasma and liver.

Nucleotide sequences of the hypervariable region of hepatitis C virus genomes obtained from plasma change rapidly during the course of infection and are believed to play a part in immunological escape and consequently in the development of persistent infection. It is not known, however, whether these changes also occur in the liver. To clarify this aspect, RNA was extracted from the plasma and liver tissue of eight patients with chronic hepatitis C. After cDNA synthesis, DNA fragments that included the hypervariable region were amplified by the polymerase chain reaction. Consensus nucleotide sequences were determined directly from the polymerase chain reaction products by the dideoxy chain termination method. The diversity of the hypervariable region was analyzed further by the polymerase chain reaction-single strand conformation polymorphism analysis. Consensus nucleotide sequences of the hypervariable region were identical between the plasma and the liver in each patient. The polymerase chain reaction-single strand conformation polymorphism analysis showed multiple DNA bands that represented different hypervariable region sequences. Comparison of the single strand conformation polymorphism patterns revealed that the number, the mobility, and the density of bands were the same between the plasma and the liver. It is concluded that the population and the diversity of hepatitis C virus quasispecies as detected by the hypervariable region sequence are the same between the plasma and the liver despite rapid mutations, indicating that rapid changes in the population of hepatitis C virus quasispecies also occur in the liver.

Amino Acid Sequence↗

PubMed1995

Prediction of relapses after interferon-alpha therapy by hepatitis C virus RNA in peripheral blood mononuclear cells.

To investigate the predictive value of hepatitis C virus (HCV)-RNA in peripheral blood mononuclear cells in the response to interferon therapy in patients with chronic hepatitis C, 15 patients with histologically proven chronic active hepatitis and who were positive for serum HCV-RNA were treated with interferon-alpha (6 million units; i.m.) every day for two weeks and then three times a week for 22 weeks. Ten of the 15 patients were responders whose alanine aminotransferase levels decreased to the normal range at the end of interferon therapy. In four of the 10 responders, HCV-RNA was not detected by reverse transcription-polymerase chain reaction in peripheral blood mononuclear cells nor in serum at the end of treatment. These four patients were complete responders, with alanine aminotransferase levels remaining normal for the next 24 weeks. In five of the 10 responders, HCV-RNA was detected in peripheral blood mononuclear cells but not in serum at the end of treatment. All of these relapsed within the next 24 weeks. In the remaining responder, HCV-RNA was detected both in peripheral blood mononuclear cells and in serum at the end of treatment. This responder also had a relapse within the next 24 weeks. Five of the 15 patients were non-responders, in whom HCV-RNA was detected both in peripheral blood mononuclear cells and in serum. Thus, detection of HCV-RNA in peripheral blood mononuclear cells may be a good clinical marker to predict relapse after interferon treatment.

Adult↗

PubMed1995

Fraction-specific populations of the hypervariable region of the hepatitis C virus in a patient with cryoglobulinemia.

Nucleotide sequences of the hypervariable region (HVR) of the E2/NS1 gene of hepatitis C virus (HCV), which are now thought to contain epitopes for neutralizing antibodies, were compared between antibody-bound HCV and free HCV in a patient with type II cryoglobulinemia. Antibody-bound HCV was immunoprecipitated with anti-human immunoglobulins from serum of the patient. Total RNA was recovered from the pellet and the supernatant, respectively, 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. Sequences of bands separated by SSCP analysis were determined by the dideoxy chain termination method. SSCP analyses revealed that the HCV populations were completely different between antibody-bound HCV and free HCV: antibody-bound HCV was composed of two bands and free HCV was composed of three bands. These five bands showed different mobility with each other on the SSCP gel. Sequencing of each band revealed distinct HVR sequences, differing in 1-34 nucleotides and 1-15 deduced amino acids. Three sequences of free HCV was similar with each other (1-5 nucleotide and 1-4 amino acid differences). On the other hand, two sequences of antibody-bound HCV had 5-34 nucleotide and 5-15 amino acid differences with free HCV. Thirteen amino acids in the 5' of HVR were completely identical in three sequences of free HCV, whereas there were three and seven amino acid differences in two sequences of antibody-bound HCV. These findings suggest that isolated specific epitopes for envelope antibodies exist within the HVR.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

PubMed1995

Sodium channel functioning based on an octagonal structure model.

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. A unique feature of the squid sodium channel is the 1,522 residue sequence, approximately three-fourths of those of the rat sodium channels I, II and III. On the basis of the sequence, and in comparison with those of vertebrate sodium channels, 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 alternating segments S2 and S4. The proposed octagonal structure model is contrasted with that of Noda et al. (Nature 320; 188-192, 1986). The octagonal structure model can explain the gating of activation and inactivation, and ion selectivity, as well as the action mechanism of both tetrodotoxin (TTX) and alpha-scorpion toxin (ScTX), and can be applied not only to the sodium channel, but also to the calcium channel, potassium channel and cGMP-gated channel.

Amino Acid Sequence↗

PubMed1995

Variations in the core region of hepatitis C virus genomes in patients with chronic hepatitis.

In each infected patient, the population of hepatitis C virus is composed of quasispecies that differ in their nucleotide sequences. Among regions in hepatitis C virus genomes, nucleotide sequences of the hypervariable region have been shown to change quickly during the course of infection. It is not known, however, whether these variations exist in the core region that has recently been suggested to contain human lymphocyte antigen class 1 restricted sites for cytotoxic T cell recognition. To clarify this, RNA was extracted from the plasma of four patients with chronic hepatitis C. After cDNA synthesis, DNA fragments that contain the core region were amplified by the polymerase chain reaction and the diversity of the core region was analyzed by the single strand conformation polymorphism analysis. Using this method, single or multiple DNA bands were observed in each patient, and representative bands showed different nucleotide sequences. Comparison of single strand conformation polymorphism patterns revealed that the population of quasispecies changed during the course of chronic infection. These changes were more remarkable in patients with high serum alanine aminotransferase levels than those with low serum alanine aminotransferase levels. Thus, sequential variations exist in the core region of hepatitis C virus in same individuals, and the population of quasispecies as determined by the sequence of the core region changes during the course of infection, which might be related to cytopathic effects of hepatitis C virus.

Alanine Transaminase↗

PubMed1995

Host dependent variation of hepatitis C virus: phylogenetic analyses.

Hepatitis C virus quasispecies in six patients from three families were separated by single strand conformation polymorphism analysis and by determination of nucleotide sequences of envelope regions containing the E1 gene segment and hypervariable region-1 of each quasispecies. Four of the six patients had multiple quasispecies. Phylogenetic analyses indicated that all quasispecies from one individual were highly homologous to each other. The homology was higher in the E1 gene segment than in hypervariable region-1. Furthermore, all quasispecies found in members of one family (husband and wife) were also highly homologous, suggesting direct intrafamilial transmission. The direction of hepatitis C virus variation in hypervariable region-1, however, seems to differ depending on the host in intrafamilial transmission.

Adolescent↗

PubMed1995

Severe chronic active hepatitis induced by UFTR containing tegafur and uracil.

A 77-year-old female patients developed severe hepatic injury after the administration of UFTR, which contains tegafur and uracil, for postoperative chemotherapy of colon cancer. Liver damage was recognized 10 months after its administration. Serum markers for viral hepatitis and various autoantibodies were negative. The wedged biopsied liver specimen revealed advanced chronic active hepatitis with periportal confluent necrosis, marked intralobular spotty necrosis, and significant proliferation of pseudo-bile ductules. Although the cessation of the drug and conservative therapies improved hepatic function, an accidental readministration of UFTR caused her severe hepatic damage again. These findings suggest that liver injury in the present case was caused by UFTR. Histological findings were unique. Although tegafur is known to worsen hepatic function when given to patients with liver cirrhosis, UFTR may also cause severe hepatic injury in those without preexisting liver disease.

Aged↗

PubMed1995

Increased renal susceptibility to gentamicin in the rat with obstructive jaundice. Role of lipid peroxidation.

To study whether renal susceptibility to nephrotoxic stimuli is increased in obstructive jaundice, the effect of gentamicin on the renal function in bile duct-ligated rats was investigated. Gentamicin (50 mg/kg/day, subcutaneously) or saline was given to bile duct-ligated rats or sham-operated rats for six days. Mortality in the bile duct-ligated group that received gentamicin was 64% whereas that in the other groups was 0%. In the bile duct-ligated group, although serum creatinine and blood urea nitrogen were minimally affected, focal granulo-vacuolar degeneration in the proximal tubule was observed, which was accompanied by an increase in renal malondialdehyde. Gentamicin significantly increased serum creatinine and blood urea nitrogen levels and caused marked degeneration in the proximal tubule in the bile duct-ligated group, which was accompanied by a further increase in renal malondialdehyde, while these changes were not observed in the sham group. The kidney in obstructive jaundice appears to be susceptible to gentamicin. Enhanced production of oxygen radicals may be responsible for this effect.

Animals↗

PubMed1995

Detection and analysis of replicating hepatitis C virus RNA in hepatocellular carcinoma tissues.

Although persistent hepatitis C virus infection is closely associated with the development of hepatocellular carcinoma, the nature of hepatitis C virus replication in the hepatocellular carcinoma tissue has not been fully characterized. To study this, carcinoma and non-carcinoma tissues were obtained from five patients with hepatocellular carcinoma. Total RNA was recovered from each tissue, and a portion of the envelope gene of replicating hepatitis C virus was amplified by minus-strand-specific reverse transcription and nested polymerase chain reaction. The amplified cDNA was examined by single strand conformation polymorphism analysis and sequencing. Hepatitis C virus replication was detected in both carcinoma and non-carcinoma tissues in four patients who were positive for serum hepatitis C virus markers. In one patient, a single species with identical envelope 2 genome was obtained from both carcinoma and non-carcinoma tissues. In the other three patients, the replicating hepatitis C virus existed as a mixture of 2-5 species with different but highly homologous (82-99%) envelope 2 genomes (quasispecies populations). The constitution of viral populations was different between carcinoma and non-carcinoma tissues. A total of ten sequences were recovered; four sequences were found in both tissues, two were found in carcinoma tissues, and four were found in non-carcinoma tissues. The difference in the constitution of quasispecies populations between carcinoma and non-carcinoma tissues confirms the unequivocal replication of hepatitis C virus in both tissues, and may imply the presence of different biological properties among hepatitis C virus with different sequences.

Amino Acid Sequence↗

PubMed1995

Expression of gap junction protein connexin 32 and E-cadherin in human hepatocellular carcinoma.

The expression of connexin 32, a major gap junction protein, and E-cadherin, an intercellular adhesion molecule that is supposed to be involved in the regulation of gap junctional intercellular communications, was examined immunohistochemically in seven specimens of human hepatocellular carcinoma and surrounding non-carcinomatous tissues. We found that the number of connexin 32-positive spots per mm2 was significantly less in hepatocellular carcinoma tissues than in the surrounding non-carcinomatous cirrhotic tissues (4360 +/- 3390/mm2 vs 10,030 +/- 3690/mm2; p < 0.01). The number in the latter was also significantly less than that in normal controls (23,560 +/- 4170/mm2). E-cadherin was expressed in all non-carcinomatous hepatocytes as well as carcinomatous cells, except for one case of Edmondson's grade III hepatocellular carcinoma. These results suggest an impairment of cell-to-cell communications in human hepatocellular carcinomas.

Cadherins↗

PubMed1995

Evaluation of the effects of esophageal varicosclerosants on local vascular occlusion and systemic blood coagulation.

The efficacy and safety of the various sclerosants available for esophageal sclerotherapy have not been adequately investigated. In the present study, we experimentally evaluated the effects on local vascular occlusion and systemic blood coagulation of five sclerosants: 5% ethanolamine oleate, 99.5% ethanol, 2% aethoxysclerol, thrombin, and n-butyl-2-cyanoacrylate. The effects were tested after injection into the auricular vein of rabbits. Prothrombin time, activated partial thromboplastin time, plasma fibrinogen level, and peripheral blood platelet count were measured before injection and 5 minutes, 1 hour, 1 day, and 7 days later. Histologic examinations were then made of the auricular vein, lungs, liver, spleen, and kidneys. In the initial period after injection of ethanol or thrombin, fibrinogen level and platelet count were significantly reduced. Except for thrombin, none of the drugs affected prothrombin time or partial thromboplastin time. Local thrombosis took place after the injection of ethanolamine oleate, ethanol, and aethoxysclerol, whereas thrombin injection did not result in local thrombosis or vascular occlusion. Cyanoacrylate produced no local thrombus formation but caused vascular occlusion. Over-dosing of thrombin and ethanol led to sudden death of animals. These findings suggest that it is necessary to assess further the safety of intravascular use of thrombin, that the other drugs seem to be usable, and that careful consideration should be given to the excess use of ethanol in clinical settings. The present animal model may be useful for evaluating various sclerosants, although findings may not be applicable to humans because of differences in vascular size.

Animals↗