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Biomedical subjects

T Shikata

Publications and source records attributed to T Shikata.

At least 73 records · Page 4Linked to original sources
PubMed1991

Animal model, virology and gene cloning of hepatitis E.

We have developed animal models of viral hepatitis E using cynomolgus and rhesus monkeys. They developed acute biochemical and histological hepatitis after the inoculation of virus particles with identical kinetics and magnitude for the sixth subpassage. Virus particles multiplied in hepatocytes and were excreted into feces via bile. Additionally, a transient viremia was recognized. Molecular cloning of virus gene cDNA was successfully accomplished from two separate libraries (HT3 and NE). These clones were expressed into polypeptides having immunological epitopes, which were used for antibody assay of sera of monkeys and patients with positive results.

Animals↗
PubMed1991

In vitro transcription of the hepatitis B virus gene by nuclear extracts of human hepatoma cells.

In vitro transcription of hepatitis B virus DNA (HBV DNA) was studied using nuclear extracts of human hepatoma cell lines. RNA polymerase II-dependent run-off transcription of pre-S mRNA under the control of pre-S1 promoter was observed in nuclear extracts obtained from HepG2 and PLC/PRF/5 cells, and the efficiencies in these extracts were significantly higher than those in nuclear extracts of non-liver cells such as HeLa, Molt-4, and Ehrlich. Analysis of run-off transcripts by the pre-S1 promoter, using deletion mutants of HBV DNA as templates and synthetic oligonucleotides as competitors, showed that hepatocyte nuclear factor 1 was necessary for initiation of in vitro transcription of pre-S mRNA. The run-off transcript of pregenome RNA was also detected and its initiation site was determined. Nuclear extracts of not only hepatoma cells but non-liver cells were active in transcription of pregenome RNA in vitro. However, run-off transcripts of S mRNA and X mRNA were not observed in this system. These results suggest that there were some differences between the mechanisms of HBV DNA transcription in vitro and in vivo. This in vitro transcription system will be useful for clarifying the mechanism regulating transcription of HBV DNA since the biochemical and functional characteristics of the nuclear factors can readily be analyzed.

Base Sequence↗
PubMed1991

Cloning and expression of cDNAs from enterically-transmitted non-A, non-B hepatitis virus.

The fragment gene of enterically-transmitted non-A, non-B hepatitis virus (ET-NANBHV) was cloned as a cDNA and inserted into an expression vector pUEX2. The recombinant protein was expressed in Escherichia coli HB101 as a fusion protein with beta-galactosidase (beta-Gal). The fusion protein reacted with the sera of infected cynomolgus monkeys and of patients from Myanmar. This reaction was highly related with ET-NANBHV infection, and obviously demonstrates in that the recombinant protein can be used for the detection of ET-NANBHV infection.

Amino Acid Sequence↗
PubMed1991

Transplantation studies on human and duck hepatocytes in athymic nude mice.

For determination of the most suitable tissue for heterotopic transplantation of exogenous hepatocytes, dissociated hepatocytes or small pieces of liver tissue were transplanted into the spleen, adipose tissue and inside the capsule of the kidney of BALB/c mice. Survival of syngeneic grafts of dissociated hepatocytes was highest in the spleen and that of pieces of liver tissue in the adipose tissue, but only the latter system was suitable for xenogeneic transplantation. Histological examination showed that a total of 50% of the human or duck liver tissue implants survived in the inguinal fat pad of athymic nude mice (BALB/c-nu). Histochemical analyses revealed that most hepatocytes transplanted into the fat pad gave positive reactions for glucose-6-phosphatase and with periodic acid-Schiff reagent at least 28 days after transplantation. Electron microscopic observation showed that these cells also maintained characteristic cellular organelles. This xenogeneic transplantation into adipose tissue should be useful in the studies on replication and infection of human hepatotropic viruses such as hepatitis B and C viruses.

Adipose Tissue↗
PubMed1991

Alloimmune neonatal neutropenia in monozygous twins. High-dose intravenous gammaglobulin therapy.

An indirect immunofluorescence test using a flow cytometer (FACS420) was useful for detection of antineutrophil antibodies (anti-NA2 antibodies) in a case of monozygous twins with alloimmune neonatal neutropenia. When high-dose intravenous gammaglobulin (300 mg/kg for five consecutive days) was given to one twin, the increase in neutrophils was not obvious. Although neutropenia persisted for about three months, no infections were observed in either of the twins.

Autoimmune Diseases↗
PubMed1991

Detection of hepatitis C virus antibodies and hepatitis C virus RNA in patients with alcoholic liver disease.

The relationship between alcoholic liver disease and hepatitis C virus was studied in 80 patients by searching for hepatitis C virus RNA with the polymerase chain reaction and by measuring hepatitis C virus antibodies. By C-100 enzyme-linked immunosorbent assay, hepatitis C virus antibodies were found in 2 of 10 patients with fibrosteatosis, 8 of 20 patients with alcoholic hepatitis, 14 of 19 patients with chronic hepatitis and 19 of 31 patients with cirrhosis. Percentages of patients with antibodies found by C-100 radioimmunoassay and by enzyme-linked immunosorbent assay based on sequence peptide 42 were lower; of the 16 patients with a low titer by C-100 enzyme-linked immunosorbent assay, 10 were negative by radioimmunoassay and 6 were negative by sequence peptide 42. By a second-generation recombinant immunoblot assay, hepatitis C virus antibodies were found in 1 of 10 patients with fibrosteatosis, 2 of 20 patients with alcoholic hepatitis, 15 of 19 patients with chronic hepatitis and 18 of 31 patients with cirrhosis. Hepatitis C virus RNA was found in 1 of 10 patients with fibrosteatosis, 3 of 20 patients with alcoholic hepatitis, 13 of 19 patients with chronic hepatitis and 20 of 31 patients with cirrhosis. Of the 37 patients with hepatitis C virus RNA, 31 had antibodies by C-100 enzyme-linked immunosorbent assay (25 patients at a high titer [cut-off index greater than 6]), and 31 had antibodies by second-generation recombinant immunoblot assay. Patients with cirrhosis and hepatitis C virus RNA had higher ALT activity than such patients without hepatitis C virus RNA (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Organ specificity of the antigens reacting with the 48-1 and S-1 antibodies in chimpanzees infected with hepatitis C virus.

48-1 and S-1 antibodies produced by lymphoblastoid cells transformed with Epstein-Barr virus were reported to be associated with infection by not only the hepatitis non-A, non-B (NANB) virus but also hepatitis delta virus. Appearance of the antigens reacting with these antibodies in the liver of chimpanzees was recently found to be a host response to alpha-interferon induced by infections of both viruses. To investigate organ specificity of these antigens, various organs obtained from chimpanzees with hepatitis C (NANB) were examined. In addition to the liver, the adrenals and spleen were found to be positive by immunofluorescence. The positive reactions of these three organs were also confirmed by radioimmunoassay. By electron microscopy, microtubular aggregates similar to those observed in the liver were detected in the adrenals, but not in the spleen. The results suggested that these antigens existed in the liver, adrenal, and probably spleen of chimpanzees infected with hepatitis C.

Adrenal Glands↗
PubMed1990

Inflammatory pseudotumor of the liver. Clinicopathologic study and review of the literature.

Clinicopathologic analysis of nine patients with inflammatory pseudotumor of the liver was reported. The age of the patients varied from 22 to 83 years old, with a male to female ratio of 8 to 1. They complained of intermittent fever and abdominal pain, and laboratory data on admission suggested an inflammatory process. The solitary or multiple, well-defined space-occupying lesions were displayed by recently advanced imaging techniques. Partial hepatectomy, laparotomy, needle biopsy, or autopsy was performed in all nine patients with diagnoses of hepatocellular carcinoma, metastatic liver tumor, or liver abscess. Histologically, these lesions were composed of dense hyalinized fibrosis and/or infiltrating inflammatory cells constituting large numbers of foamy histiocytes, lymphocytes, and plasma cells. Obliterating phlebitis of relatively large branches of the portal vein was found, thus providing a diagnostic clue to distinction from the primary hepatic cancer by imagings. Considering the clinicopathologic features and the patients' histories, in which four patients had been in the Southeast Asian countries or India, it is possible that infection of microorganisms through the portal vein could participate in these lesions as a cause. Two patients died of causes probably related to this lesion, indicating poor prognosis in some patients, in contrast to the generally fair prognosis of previously published cases.

Adult↗
PubMed1990

Further studies of 48-1 antigen in serial liver biopsies from chimpanzees infected with hepatitis delta virus.

The 48-1 antibody, initially reported to react specifically with non-A, non-B infected liver tissue, has been found to react also with liver specimens from chimpanzees infected with hepatitis delta virus (HDV). To clarify further the relation between HDV and appearance of the antigen reacting with the 48-1 antibody (48-1 Ag), immunoperoxidase studies were carried out on serial liver specimens from chimpanzees infected with HDV. Immunohistochemical and serological findings suggested that the appearance of 48-1 Ag paralleled that of HDV. Double immunoperoxidase staining revealed HDAg in the nucleus and 48-1 Ag in the cytoplasm of the same hepatocytes as well as in different hepatocytes separately. The course of appearance of microtubular aggregates paralleled that of 48-1 Ag. The present results suggested that expression of 48-1 Ag was related to infection with HDV, probably because expression of this antigen is induced from the host genome.

Animals↗
PubMed1990

Isolation and purification of a non-A, non-B hepatitis-associated microtubular aggregates protein.

Blood-borne type non-A, non-B (NANB) hepatitis-associated microtubular aggregates protein was isolated and partially sequenced. The microtubular aggregates were isolated from the hepatocytes of NANB-infected chimpanzees and were found to have a buoyant density in sucrose solution of 1.21 to 1.23 g/ml. A single protein, recognized by our anti-microtubular aggregates monoclonal antibodies, was found to have an Mr of 44,000 (p44). This p44 protein was not found in uninfected chimpanzees. We determined a partial amino acid sequence for p44, and showed that it has no homology to any known proteins.

Amino Acid Sequence↗
PubMed1990

Persistence of hepatitis B virus DNA after serological clearance of hepatitis B virus.

Using Southern blot technique, the state of hepatitis B virus (HBV) DNA in liver tissue was investigated in 16 patients who were sero-negative for hepatitis B surface antigen (HBsAg) but positive for its antibody (anti-HBs). In only one case, was HBV DNA found in liver tissue in a heterogeneously integrated form. In this case, digestion with Taq I demonstrated integrated HBV DNA as two definite bands at 1.8 and 0.5 kbp. This suggests that HBV DNA in some cases persists even after HBV infection has been cleared serologically. It is possible that this persistence of HBV DNA plays an important role in hepatocarcinogenesis.

DNA Probes↗