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T Miyamura

Publications and source records attributed to T Miyamura.

At least 181 records · Page 10Linked to original sources
PubMed1991

Molecular cloning of cDNA of hepatitis C virus (HCV) genome from a healthy carrier in an aboriginal community in Taiwan with high prevalence of HCV infection.

We analyzed hepatitis C virus (HCV) obtained from a healthy HCV carrier in an aboriginal community with high prevalence of HCV infection. By use of random primers and specific oligonucleotide primers, a cDNA fragment of putative non-structural 3 (NS3) region of the HCV genome was cloned by reverse transcription-polymerase chain reaction (RT-PCR) using RNA extracted from a serum sample of a healthy HCV carrier in Taur-Yuan village. The nucleotide and deduced amino acid sequences from the 583 nucleotides long cDNA were compared with those of equivalent region of HCV of other previously reported clones: [J1, HCV-J (regarded as major type of HCV in Japan) and US prototype]. They had 93.7% (546/583), 93.1% (543/583) and 80.4% (469/583) homology at the nucleotide level and 96.9% (188/194), 96.9% (188/194) and 91.8% (178/194) homology at the amino acid level, respectively. These results showed that HCV prevalent in an aboriginal community in Taiwan is more similar to Japanese type than to the US prototype.

Amino Acid Sequence↗
PubMed1990

Alternative splicing of hepatitis B virus RNAs in HepG2 cells transfected with the viral DNA.

We identified a novel spliced RNA of 2.6 kb from a human hepatoma cell line HepG2 transfected with the hepatitis B virus (HBV) genome. The splicing acceptor site of the novel 2.6-kb RNA (position 489) was shown to be common to that of the previously described 2.1-kb spliced RNA which codes for an altered core antigen lacking the carboxy-terminal amino acid, cysteine. However, the donor site of the 2.6-kb RNA is different from any of the spliced RNA reported and located at 538 nucleotides (nt) downstream of the donor site of the 2.1-kb RNA. Introduction of single-base change mutations in the consensus sequence of the donor site of the 2.1-kb RNA maintained the splicing by using the cryptic donor site. The amount of the 2.6-kb spliced RNA was unchanged by these mutations. These results suggest independent regulations for the synthesis of the 2.1- and 2.6-kb spliced RNAs.

Amino Acid Sequence↗
PubMed1990

Blood screening for non-A, non-B hepatitis by hepatitis C virus antibody assay.

Hepatitis C virus (HCV) antibody was detected in 1499 donor sera by radioimmunoassay using an antigen expressed in yeast from a cDNA clone of the HCV genome. Eighteen samples over 4200 counts per minute (cpm) were considered to contain infectious HCV because these recipients developed typical posttransfusion non-A, non-B hepatitis after transfusion. The antibody-positive sera were all within the normal range of ALT levels. This assay system is thus useful for the screening for blood transfusion.

Adult↗
PubMed1990

Hepatitis C virus infection is associated with the development of hepatocellular carcinoma.

A possible causative role for the recently discovered hepatitis C virus (HCV) in the development of hepatocellular carcinoma (HCC) was investigated by assay of sera from HCC patients in Japan for antibodies to a recombinant HCV antigen and to hepatitis B virus (HBV) antigens. Among the 253 HCC patients examined, 156 (61.7%) had no serum markers of either a previous or a current HBV infection (group I), 46 (18.2%) were negative for HBV surface antigen but positive for anti-HBV surface and/or anti-HBV core antibody, indicating the occurrence of a previous, transient HBV infection (group II), and 51 (20.2%) were chronically infected HBV carriers as evidenced by positivity for HBV surface antigen (group III). The prevalence of HCV antibody in group I (68.6%) and II (58.7%) patients was significantly higher than for group III (3.9%) or in 148 additional patients with other (non-HCC) cancers (10.1%) (P less than 0.01). Thus, there appears to be a strong association between HCV infection and the development of HCC, particularly in patients for which HBV infection cannot be implicated as a causative factor. The data also suggest an additional mode of transmission for HCV other than blood transfusion, since a history of blood transfusion was shown in only about 30% of the HCV antibody-positive HCC patients in groups I and II. A high prevalence of HCV antibody was also shown among patients with HCC whose disease was originally thought to be due to very high ethanol consumption.

Blood Transfusion↗
PubMed1990

Allele loss on chromosome 16 associated with progression of human hepatocellular carcinoma.

Loss of heterozygosity on chromosome 16 is a common genetic alteration in human hepatocellular carcinoma (HCC). To clarify the pathogenetic significance of allele loss on chromosome 16, we performed restriction fragment length polymorphism analysis of 70 surgically resected tumors by using 15 polymorphic DNA markers for chromosome 16. Loss of heterozygosity on chromosome 16 was detected in 36 (52%) of 69 informative cases, and the common region of allele loss in these 36 tumors was located between the HP locus (16q22.1) and the CTRB locus (16q22.3-q23.2). These losses occurred more frequently in HCCs of poor differentiation, of larger size, and with metastasis, whereas they were not detected in HCC at the earliest stage. In addition, these losses were not associated with presence or absence of hepatitis B virus DNA integration or hepatitis C virus infection. These results show that loss of heterozygosity on chromosome 16 is a late event occurring after hepatocarcinogenesis and strongly suggest that this phenomenon is involved in enhancement of tumor aggressiveness during progression of HCC.

Alleles↗
PubMed1990

Detection of antibody against antigen expressed by molecularly cloned hepatitis C virus cDNA: application to diagnosis and blood screening for posttransfusion hepatitis.

A cDNA clone has been derived from the plasma of a chimpanzee with chronic non-A, non-B viral hepatitis (NANBH). We have assayed for antibodies reacting with the encoded antigen in sera from posttransfusion hepatitis patients (643 samples from 23 patients) and their corresponding donors collected during the past 10 years in Japan. The antibody was detected in 15 out of 17 (88.2%) posttransfusion NANBH (PT-NANBH) patients whose sera over time displayed multiple alanine aminotransferase (ALT) peaks. In general, the antibody was detected after several peaks of serum ALT elevations and, once detected, it persisted for years. In contrast to the patients of chronic hepatitis, the antibody was barely detected in patients with a single episode of ALT elevation (1 out of 6). Of the 15 well-defined cases of PT-NANBH that showed multiple ALT peaks and hepatitis C virus seroconversions, 11 (73.3%) were shown to be transfused with at least one unit of blood positive for the antibody. The retrospective analysis showed that all tested donor blood found to be positive for the antibody had been transfused to recipients who afterwards developed NANBH. These data strongly suggest that the cloned cDNA originated from an etiological agent of NANBH termed the hepatitis C virus. Furthermore, the present study demonstrates that had the screening been done with the anti-hepatitis C virus assay, 11 out of 17 (64.7%) cases of chronic PT-NANBH and 1 out of 6 (16.6%) acute PT-NANBH would have been prevented. The antibody assay thus can be used for diagnosis and blood screening for PT-NANBH.

Adult↗
PubMed1990

The putative nucleocapsid and envelope protein genes of hepatitis C virus determined by comparison of the nucleotide sequences of two isolates derived from an experimentally infected chimpanzee and healthy human carriers.

cDNA fragments of a 5'-terminal region of the hepatitis C virus (HCV) genome were isolated by the reverse polymerase chain reaction from RNA extracted from plasma samples of healthy Japanese carriers. Their nucleotide sequence was compared with that of the original isolate which had been passaged twice in chimpanzees. No deletions or insertions were observed between the two sequences in the regions examined. Both the 5' untranslated and putative nucleocapsid (core) protein regions were highly conserved (99% and 91% nucleotide identities, respectively). In contrast, the region immediately downstream which encodes a putative envelope glycoprotein(s) showed only 74% nucleotide identity between the two isolates. At the polypeptide level, the core and envelope domains showed 97% and 75% amino acid identities, respectively. This envelope variation may reflect the adaptation of HCV to the different hosts and/or the result of immunological selection. The highly conserved nucleotide sequence of the 5' untranslated and core regions may play an important regulatory role in the life cycle of HCV.

Amino Acid Sequence↗
PubMed1990

Prevalence of hepatitis C virus antibody among healthy blood donors and non-A, non-B hepatitis patients in Thailand.

With the antigen expressed in yeast from a cDNA clone encoding a non-structural region of newly discovered hepatitic C virus (HCV) genome, the prevalence of HCV antibody in people in Thailand was investigated. Antibody was detected in 2.6% of healthy blood donors and in 2.8% of healthy pregnant women. These prevalence rates were higher than those reported previously from Japan, USA and European countries. Among community-acquired, sporadic cases of acute and chronic non-A, non-B hepatitis, however, only 5.7% and 15.4% were shown to possess the antibody, respectively. Among hepatocellular carcinoma patients who were negative for hepatitis B surface antigen in the sera, 11.1% had antibody to HCV. These seroepidemiological data suggest that HCV plays an important role as an etiological agent in Thailand; however, other agents must also be involved in etiologic agents of viral hepatitis and chronic liver disease.

Adolescent↗
PubMed1990

Detection of hepatitis C virus cDNA sequence by the polymerase chain reaction in hepatocellular carcinoma tissues.

We found the presence of hepatitis C virus (HCV) infection in liver tissues of hepatocellular carcinoma (HCC) patients who had antibodies to HCV but no serological markers for hepatitis B virus infection by the sensitive reverse transcription/polymerase chain reaction (R/PCR) method. The primers used were derived from the non-structural (NS) 3 and/or the structural (C/E) region. Amplified cDNA sequences of HCV were detected in either cancerous or non-cancerous portion of liver tissues from four out of eight HCC patients with primers of NS3 region. Similar but less efficient results were obtained with primers of C/E region. These results indicate that HCV persists in the liver tissue of HCC. A possible role of persistent infection of HCV for the development of HCC is discussed.

Base Sequence↗
PubMed1989

An assay for circulating antibodies to a major etiologic virus of human non-A, non-B hepatitis.

A specific assay has been developed for a blood-borne non-A, non-B hepatitis (NANBH) virus in which a polypeptide synthesized in recombinant yeast clones of the hepatitis C virus (HCV) is used to capture circulating viral antibodies. HCV antibodies were detected in six of seven human sera that were shown previously to transmit NANBH to chimpanzees. Assays of ten blood transfusions in the United States that resulted in chronic NANBH revealed that there was at least one positive blood donor in nine of these cases and that all ten recipients seroconverted during their illnesses. About 80 percent of chronic, post-transfusion NANBH (PT-NANBH) patients from Italy and Japan had circulating HCV antibody; a much lower frequency (15 percent) was observed in acute, resolving infections. In addition, 58 percent of NANBH patients from the United States with no identifiable source of parenteral exposure to the virus were also positive for HCV antibody. These data indicate that HCV is a major cause of NANBH throughout the world.

Antibodies, Viral↗
PubMed1989

Phosphorylation of casein components by tyrosine-specific protein kinases.

The phosphorylation of different caseins by a number of tyrosine-specific kinases has been studied. The different kinases showed a range of specificities, suggesting differences in recognition mechanisms. The site of phosphorylation of alpha s2-casein by one phosphorylase has been identified, and compared with analogous sites in other proteins.

Caseins↗
PubMed1989

Detection and mapping of spliced RNA from a human hepatoma cell line transfected with the hepatitis B virus genome.

HepG2 cells, known to support the replication and virion formation of hepatitis B virus (HBV), were transfected with a cosmid constructed to contain 12 tandem head-to-tail repeats of the HBV genome for effective HBV genome expression. We detected previously identified RNAs of 3.3, 2.3, and 2.0 kilobases (kb) that code for core antigen, large surface antigen, and middle/major surface antigen, respectively. We also detected four additional RNAs of 2.1, 1.7, 1.1, and 0.7 kb [the lengths exclude the poly(A) tail]. S1 mapping and nucleotide sequencing data showed that the 2.1-kb RNA is a spliced RNA whose 5' and 3' ends are identical to those of the 3.3-kb RNA. The results suggest that the 2.1-kb RNA codes for an altered core antigen lacking the last amino acid, cysteine, and that expression of the 3.3-kb pregenomic RNA is regulated, at least in part, by splicing. The map positions of the 1.7- and 1.1-kb RNAs suggest that they code for the carboxyl-terminal portions of the putative polymerase, whereas the 0.7-kb RNA codes for the X protein.

Antigens, Viral↗