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Biomedical subjects

M Omata

Publications and source records attributed to M Omata.

At least 487 records · Page 27Linked to original sources
PubMed1990

[Role of reactive oxygen species (Ros) in model immune complex nephritis].

In an attempt to examine the role of reactive oxygen species on bivalent hapten immune complex glomerulonephritis, superoxide dismutase (SOD) concentration in renal tissue was studied by Electron Spin Resonance (ESR) and the protective effect of radical scavengers were evaluated. Injection of immune complex (IC) induced severe glomerulonephritis, characterized by neutrophil and/or monocyte infiltration in glomeruli in an association with proteinuria. SOD concentration in renal tissue decreased when neutrophil and/or monocytes infiltration and proteinuria developed, indicating a possible role of reactive oxygen species on renal injury. SOD, superoxide scavenger, and catalase (CAT), which destroy hydrogen peroxide, apparently reduced proteinuria on 14th day (18.5 +/- 3.17 mg/day, 20.7 +/- 7.35 mg/day, respectively, in comparison with control group, 29.5 +/- 4.21 mg/day), but there was no statistical significance. On the other hand, hydroxy radical scavenger, dimethylthiourea (DMTU) significantly reduced proteinuria (15.3 +/- 4.21 mg/day) and remarkable improvement in renal histology was observed. It is concluded that reactive oxygen species, especially hydroxy radical, play a significant role on renal injury in bivalent hapten immune complex glomerulonephritis.

Animals↗
PubMed1990

[Detection of ras gene mutations of primary hepatic malignant tumors by polymerase chain reaction and direct sequencing method].

Ras genes are converted to active oncogenes by point mutations occurring in either codon 12, 13 or 61. We used polymerase chain reaction and direct sequence method for the analysis of these mutations. We examined 13 hepatocellular carcinomas, 8 cholangiocarcinomas, 2 hepatoblastomas and 1 biliary cystadenocarcinoma. Of these tumors, ras gene mutations were detected solely in cholangiocarcinomas. Cholangiocarcinoma showed a high incidence of K-ras gene mutation. Among 8 patients with cholangiocarcinoma, the mutation was detected at codon 12 in 4 and at codon 61 in 1. The incidence of K-ras gene mutation was especially high in the hilar type of cholangiocarcinoma as compared with the peripheral type.

Adenoma, Bile Duct↗
PubMed1989

Histological changes of the liver by treatment of chronic non-A, non-B hepatitis with recombinant leukocyte interferon alpha. Comparison with histological changes in chronic hepatitis B.

We have treated 17 patients with non-A, non-B chronic hepatitis by recombinant interferon alpha (0.3-9 megaunits for 4-28 weeks). In six patients, serum aminotransferase levels fell to normal or near-normal range during treatment. The mean levels of serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in 17 patients fell from 156 +/- 80 (mean +/- SD) and 213 +/- 135 at the beginning of treatment to 94 +/- 49 and 112 +/- 71, respectively, at the end of treatment. In 12 patients, liver biopsies were performed before and after (or during) the treatment, and histological activity indices (HAI) were blindly examined by two independent observers. For comparison, we examined histological changes of pre- and posttreatment liver biopsies of 19 patients who were treated by recombinant interferon for chronic hepatitis B. Mean HAI scores improved from 10.0 to 5.4 after treatment in non-A, non-B chronic hepatitis. The most marked reduction was noted in scores of portal inflammation and hepatocellular degeneration and/or necrosis. No such reduction was observed in B-viral chronic hepatitis. These data indicated that rapid biochemical resolution by the treatment was related to histological improvement of the liver in our patients with non-A, non-B hepatitis.

Adult↗
PubMed1989

Liver diseases associated with hepadnavirus infection. A study in duck model.

Among four hepadnaviruses, we studied liver diseases of duck hepatitis B virus (HBV)-infected animals. There was close correlation of viral infection and development of liver diseases. The presence of hepatocellular carcinoma (HCC) was observed in Chinese ducks. We previously showed that duck HBV DNA was integrated in the neoplastic cells. Analysis of duck HBV integrants revealed the similarity to the reported structures of HBV integrants. To develop effective antiviral therapy, we tested adenine arabinoside (Ara-A), phosphonoformate, azido-deoxythymidine (AZT), and dideoxycytidine (DDC) in this in vivo model. Significant suppressive effects on viral replication were observed by phosphonoformate and adenine arabinoside, but AZT and DDC failed to show significant antiviral effects. This may be related to a unique pathway of replication in hepadnaviruses.

Animals↗
PubMed1989

[The influence of dose of transfusion and component of blood on the incidence of post-transfusion hepatitis].

Two thousand five hundred ninety-six consecutive patients who received blood transfusion for the first time within one week and had no liver dysfunction before transfusion had been selected from 8637 patients who received blood transfusion at the hospital between 1982 and 1987. The influence of dose, components of transfused blood and sex, age of recipients on the incidence of post-transfusion hepatitis was investigated. The rate of development of hepatitis depended on the dose of transfusion, not on sex and age of recipients. The rate of development of hepatitis raised as number of transfused blood increased without limiting point to 100%. The carrier rate of healthy population of non-A, non-B hepatitis virus was estimated 1.39%. Stored blood, concentrated red blood cell and fresh blood are high risk components and fresh frozen plasma was low risk component.

Hepatitis↗
PubMed1989

[Detection of ras gene mutations of pancreatic tumors by polymerase chain reaction and direct sequencing method].

Ras genes (H-,K-,N-ras) are converted to active oncogenes by point mutations occurring in either codon 12, 13 or 61. We analyzed 19 pancreatic tumors (formalin fixed paraffin embedded tissue) of these codons by a method to directly sequence nucleotides around codons 12/13 and 61 of the three ras genes, using polymerase chain reaction and direct sequencing method. Of 19 pancreatic tumors, all 17 duct cell carcinomas involving 2 mucous producing pancreatic cancers had point mutations of the K-ras codon 12, but 2 islet cell tumors had ano point mutation around codons 12, 13, 61 of the three ras genes. Extremely high incidence of ras gene mutation may be relevant to certain pathogenesis of pancreatic cancers.

Base Sequence↗
PubMed1988

Experimental portal fibrosis produced by intraportal injection of killed nonpathogenic Escherichia coli in rabbits.

An attempt was made to develop an animal model for the study of the etiology of noncirrhotic portal fibrosis or idiopathic portal hypertension based on the assumption that it is related to chronic abdominal infection. Rabbits were given killed nonpathogenic Escherichia coli intraportally or intravenously. The animals to which a mixture of killed E. coli and rabbit antiserum (aggregated E. coli) was given intraportally developed remarkable histologic changes in the liver. The early inflammatory reactions in the portal area and parenchyma were followed by rapid disappearance of inflammation and development of portal fibrosis with bile duct proliferation. Three intraportal challenges with aggregated E. coli were sufficient to produce pronounced portal fibrosis, although there was considerable variation in response among individual animals. This procedure also produced splenomegaly, and in some animals marked portal hypertension. Injection of nonaggregated killed E. coli into the portal vein or aggregated E. coli into the ear vein also caused similar hepatic changes, but they were milder in degree. These histologic changes resemble portal fibrosis seen in idiopathic portal hypertension and, less closely, pericholangitis associated with inflammatory bowel disease in humans.

Animals↗
PubMed1988

Expression of pre-S1, pre-S2, and C proteins in duck hepatitis B virus infection.

We have examined the expression of duck hepatitis B virus (DHBV)-associated proteins in experimentally infected ducks by an immunoblot (Western) method. The DHBV-related core protein, C protein, was identified at the position of 35,000 Da (P35). Pre-S proteins were recognized as two major bands (P37 and P28), the former representing pre-S1 and the latter pre-S2 protein. Expression of the proteins was examined in the early phase of infection in ducklings sequentially sacrificed from 6 hr postinoculation to 10 days. C protein (P35) was detected as early as 24 hr postinoculation. This timing coincided with the exponential increase of RNA transcripts and double-stranded viral DNA. Pre-S1/S2 proteins were detected at 3 days postinoculation. The early appearance of C protein suggested that the proteins were utilized for nucleic acid packaging. On the other hand, the late appearance of pre-S1/S2 proteins suggested that they were utilized in the production of virions near the end of the replication cycle.

Animals↗
PubMed1988

Integrated structures of duck hepatitis B virus DNA in hepatocellular carcinoma.

The structure of integrated viral DNA in a hepatocellular carcinoma of a duck from Chi-tung county in China was analyzed. Three different clones of integrated viral DNA, lambda DHS 6-1, lambda DHS 6-2, and lambda DHE 6-2, were obtained from the neoplastic portion of the liver by molecular cloning. One of the three clones, lambda DHS 6-1, showed inverted repetition of integrated viral DNA with chromosomal flanking sequences. Another clone, lambda DHS 6-2, showed a head-to-head configuration of the core and surface gene regions of duck hepatitis B virus (DHBV) DNA. The virus-chromosome junctions were often located near direct repeat 1 or 2 of DHBV DNA in three independent clones. Nucleotide sequences at the virus-virus junctions in two clones, lambda DHS 6-1 and 6-2, indicated the possible rearrangement of chromosomal DNA and recombination of viral DNA. DHBV DNA appears to be integrated into the genome of hepatocytes in a manner similar to that of human and woodchuck hepatitis viruses. Thus, the duck system may serve as a useful animal model for the study of human hepatocarcinogenesis.

Animals↗
PubMed1987

Correlation of hepatitis B virus DNA and antigens in the liver. A study in chronic liver disease.

Hepatitis B virus deoxyribonucleic acid (DNA) and antigens (HBsAg and HBcAg) were studied in liver biopsy specimens from 105 HBsAg-positive patients with chronic liver diseases. Free or integrated viral DNA, or both, was detected in 83 of 105 (79%) patients, whereas HBsAg and HBcAg were demonstrated immunohistologically in 96 (91%) and 39 (37%), respectively. Of 60 patients with detectable free viral DNA, 38 (63%) were positive for HBcAg, whereas only 1 of 45 (2%) with either integrated viral DNA alone (n = 23) or no detectable viral DNA (n = 22) was positive for HBcAg (p less than 0.001). Furthermore, the amount of HBcAg was positively correlated with the amount of free viral DNA in the liver tissue. In contrast, HBsAg was well expressed not only in the liver with free viral DNA, but also in the liver with integrated DNA. These data suggest that the synthesis of HBcAg is primarily directed by free viral DNA, whereas that of HBsAg may be directed by free as well as integrated viral DNAs.

Adult↗
PubMed1986

Hepatitis B virus RNA transcripts and DNA in chronic liver disease.

To study the relation between gene expression of hepatitis B virus (HBV) and liver disease, we studied HBV RNA transcripts and DNA in liver-biopsy specimens from 30 patients with chronic liver disease (17 seropositive for hepatitis B surface antigen and 13 seronegative). HBV-specific RNA was found in all the seropositive patients and in none of the seronegative patients. Two major RNAs, sizes 29S (long) and 21S (short), were found in nine seropositive patients, of whom seven had free HBV DNA and eight were seropositive for hepatitis B e antigen. Six of the nine patients had hepatitis B core antigen in hepatocytes and active liver disease. In contrast, inactive liver disease was noted in the remaining eight seropositive patients, who had only one (21S) RNA. None of these patients had free HBV DNA (five of eight had integrated DNA) or hepatitis B core antigen in hepatocytes. Hybridization analysis suggested that 29S and 21S RNAs are messenger RNAs of hepatitis B core antigen and hepatitis B surface antigen, respectively. These data indicate that the free DNA and its products are causally related to the activity of liver disease and that once HBV DNA has been integrated, the disease will become quiescent. None of the determinants were identified in patients seronegative for hepatitis B surface antigen.

Adult↗
PubMed1986

Integration of hepatitis B virus DNA in hepatocellular carcinoma.

Integration of hepatitis B virus (HBV) DNA into genomic DNA was investigated in 34 livers bearing hepatocellular carcinoma (HCC) by Southern blot hybridization using 32P-labeled, cloned and purified HBV DNA as a probe. Rehybridization of nitrocellulose paper with a probe containing only the cloning vector was performed after dehybridization to avoid possible false-positive results. Integrated HBV DNA was detected in all 9 hepatitis B surface antigen (HBsAg)-seropositive cases and 3 out of 25 (12%) HBsAg seronegative cases. The hybridization patterns of viral DNA were the same among several cancer nodules in two HCC cases with multiple liver tumors, indicating unicentric hepatocarcinogenesis in these two cases. These results, obtained with avoidance of false-positive results, showed that only a minority of HBsAg-seronegative HCC cases in Japan had demonstrable HBV DNA in the tumors studied by the Southern blot hybridization technique.

Carcinoma, Hepatocellular↗
PubMed1986

Appearance of viral RNA transcripts in the early stage of duck hepatitis B virus infection.

Sequential analysis of duck hepatitis B virus (DHBV) DNA and RNA transcripts in the liver of the early stage of infection was carried out using 1-day-old ducklings inoculated with DHBV-positive serum. Using Southern blot analysis, a band of supercoiled DHBV DNA was detectable at 6 hr, when DHBV-specific poly[A]+RNA was also observed by Northern blot analysis as a faint smear below 3-kb. Bands of RNA at 3.5, 2.7, and 2.5 kb were detected at 12 hr, just before single-stranded viral DNA was detected. A prominent increase in the amount of viral RNA was demonstrated (between 12 hr and 3 days) prior to the increase of DHBV DNA (between 3 and 6 days). Our results suggest that 3.5-kb DHBV-specific RNA synthesized from supercoiled DNA may act as a template of reverse transcription, and that all steps of the replication pathway proposed by Summers and Mason (1982, Cell, 29, 403-415) are completed during 3 days.

Animal Diseases↗