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Biomedical subjects

F Mizuno

Publications and source records attributed to F Mizuno.

At least 73 records · Page 4Linked to original sources
PubMed1980

Insoluble glucan hydrolyzing enzymes from oral bacteroides.

Crude enzymes (En(C)) which hydrolyze insoluble glucan produced by Streptococcus mutans FA-1 were extracted from Bacteroides oralis obtained from human dental plaque. Extracellular insoluble glucan of S. mutans (IsG) and the one which was partially modified by Smith degradation (M-IsG) were used as substrates. Commercial dextran (M.W. 2,000,000) was used as control. Composition of the types of glucosidic linkages of the glucans was determined by methylation analysis. The ratio of the alpha-(1--6) linkage and alpha-(1--3) linkage was 96.3% and 0.5% for dextran, 29.2% and 55.1% for IsG and 11.9% and 84.9% for M-IsG. En(C) was extracted by salting out of the culture of B. oralis with 60% saturation of ammonium sulfate. En(C) hydrolyzed IsG, M-IsG and dextran, whereas commercial dextranase (alpha-1,6 glucanase) hydrolyzed only dextran. IsG was treated with the commercial dextranase until no glucose was detected in the medium, and the remaining material was used for the substrate of enzymes. Release of glucose was detected from the substrate by treatment with En(C), but not with commercial dextranase. These results indicated that En(C) of Bacteroides oralis contained at least two types of glucanase, one being dextranase which hydrolyzes the alpha-(1--6) linkage and the other the so-called mutanase which hydrolyzes the alpha-(1--3) linkage.

Bacteroides↗
PubMed1978

Epstein-Barr virus and human chromosomes: close association of the resident viral genome and the expression of the virus-determined nuclear antigen (EBNA) with the presence of chromosome 14 in human-mouse hybrid cells.

Fourteen hybrid clones derived from the fused cultures of human lymphoblastoid FV5 cells and 5-bromodeoxyuridine-resistant mouse fibroblastic MCB2 cells grown in hypoxanthine/aminopterin/thymidine selective medium were examined for the presence of Epstein-Barr virus (EBV) DNA, the expression of the virus-determined nuclear antigen (EBNA), and the presence of human chromosomes, in the course of serial passage in vitro. Among the hybrid clones tested, 3 were positive for EBV DNA and EBNA, whereas the remaining 11 were totally negative. The chromosome investigations showed that human chromosome 14 was consistently involved in all three EBV genome-positive and EBNA-positive hybrid clones, but not in any negative clones. In 10 subclones isolated from 1 of the 3 positive clones, all of which contained only chromosome 14 of the human chromosomes, a concordant segregation of EBNA, EBA DNA, and chromosome 14 was evident. These findings suggest that the resident EBV genome is closely associated with chromosome 14 and the presence of this particular chromosome alone is sufficient for the maintenance and the expression of EBV genetic information in human lymphoblastoid cells.

Antigens, Viral↗
PubMed1978

Regulation of interferon production by dibutyryl cyclic GMP in serum-free human diploid cell cultures.

The mechanism for regulating interferon production was investigated in relation to accentuation of production in serum-free human diploid cells (strain WI-38) treated with N2,O2-dibutyryl guanosine 3',5'-cyclic monophosphate (db-cyclic GMP). Interferon production in serum-free WI-38 cell cultures in response to Newcastle disease virus (NDV) was greatly reduced. In these cells, there was decreased incorporation of 5-3H-uridine into the acid-insoluble fraction, but unimpaired incorporation of U-14C-L-leucine, as compared with serum-containing cultures. When serum-free cell cultures were treated with 0.2 mM-db-cyclic GMP, incorporation of both 5-3H-uridine and U-14C-L-leucine was increased and there was an 8-fold enhancement in the yield of interferon in response to NDV. Induction of db-cyclic GMP-treated cells by NDV in the presence of cycloheximide and actinomycin D suggests that db-cyclic GMP enhances transcription of the interferon gene, and thereby augments interferon production.

Blood↗
PubMed1978

Interferon synthesis in human diploid cells pretreated with insulin.

Interferon production by Newcastle disease virus in human diploid (WI-38) cells was greatly reduced in the absence of serum. Pretreatment of the serum-free cells with insulin in excess of 1.2 IU/ml for 2 h before induction considerably increased the amount of interferon produced. No enhancement of interferon production was seen when the cells were exposed to insulin 2 h after induction or later. The insulin's effect persisted for at least 6 h after its removal, but not for 24 h. A possible mechanism of insulin action is discussed.

Animals↗
PubMed1978

Interaction between Epstein-Barr virus and type-C virus in human cells.

The interaction between EBV and type-C viruses was studied in our FVNC experimental system, in which EBV and type-C viral genomes are contained in each cell. The data indicate that the human lymphoid FVNC cells are sensitive to both EBV and type-C virus exposure, showing high frequencies of induction of both repressed viral genomes. The two different viral genomes may be associated with different chromosomes in individual cells.

Antigens, Viral↗
PubMed1978

Antibody-dependent autologous lymphocyte cytotoxicity against cells freshly transformed by Epstein-Barr virus.

Cytotoxicity against lymphocytes freshly transformed by EBV was studied in an autologous system by trypan blue exclusion of EBNA-positive cells and 51Cr-release assay. When EBV-tranformed lymphocytes were incubated with EBV-positive serum and autologous unfractionated lymphocytes or K-cells from sero-positive healthy donors, the transformed cells were significantly damaged. The cytotoxicity against newly produced EBNA-positive lymphocytes was also remarkable when sero-positive healthy donor lymphocytes were exposed to EBV, immediately followed by incubation with positive serum. In contrast, EBV-transformed cells incubated with autologous lymphocytes or T-cells alone were not significantly affected. EBV-positive serum alone was also not cytotoxic, regardless of inactivation. These results strongly suggest that antibody-dependent cellular cytotoxicity (ADCC) plays an important role in immunological defence against EBV oncogenesis in healthy humans. However, ADCC was not seen when immunosuppressed patients were examined.

Antibodies, Viral↗
PubMed1978

Neisseria in early stage of dental plaque.

Neisseria in the early stage of dental plaque was studied. Two hundred seventeen strains of Neisseria were isolated from the 12-hour plaque of 9 subjects by using lactose-agar. The isolated strains were divided into 6 major groups with biological characteristics. One hundred twenty-one strains (56%) produced glycogen-like polysaccharide from sucrose. They were divided into 3 groups. Groups 1 and 2 were identified as N. mucosa and N. sicca, respectively. There were 106 strains of N. sica, being the most predominant of the species. The number of strains not producing polysaccharide was 96 (44%). Groups 4 and 5 were Branhamella and N. subflava. The absorption spectra of the ethanol extracts of the pigment in each group were similar and this result supported propriety of the classification by biological characteristics. The adhesiveness of Neisseria to the glass plate was examined. Approximately one-half of N. sica showed an adhesion capacity.

Adhesiveness↗
PubMed1976

Growth in semisolid agar medium of human cord leukocytes freshly transformed by Epstein-Barr virus.

The semisolid agar method for the selective growth of transformed cells was applied to investigations of Epstein-Barr virus (EBV) transformation. When 1 X 10(5) HUMAn umbilical-cord blood leukocytes were seeded in agar medium immediately after EBV exposure, about 100 colonies developed in each dish. The occurrence of colonies correlated well with dilutions of EBV inoculum. These colonies were composed of lymphoblasts, were positive for EBV-determined nuclear antigen immunofluorescence, and consistently resulted in the establishment of cell lines. In cord leukocyte cultures exposed to EBV, cells capable of growing in semisolid agar medium appeared early and increased rapidly, though the total numbers of leukocytes and control cultures decreased during the first several days.

Cell Line↗
PubMed1976

Dextran degrading activity of oral microbial flora.

Dextran degrading activity of the human oral microflora was detected by culturing in TYD broth (Tryptose 1.0%, Yeast extract 0.3%, Dextran T-150 (Pharmacia, MW 150,000) 0.15%). All of the plaue and saliva samples collected from 10 subjects showed a dextran degrading activity, both cultured aerobically and anaerobically, while the anaerobic culture was more active than the aerobic. Furthermore, some individual differences were observed in their activity. Crude enzyme(s) was extracted from the supernatant of a mixed culture of plaque sample by adding ammonium-sulfate to 0.6 and 0.8 saturation (called E-1 and E-2, respectively). E-1 contained 2 dextran-degrading enzymes, one being thought to be an endo-enzyme, with the optimal of H being 5.0 and the other an exo-enzyme with the optimal pH being 7.0-7.5. On the other hand, E-2 contained 1 enzyme of the endo-type. Thirteen strains producing dextranase were isolated from the plaque and were identified as Bacteroides oralis-like organisms. Several other organisms were thought to produce dextranase, although we failed to isolate them in this experiment.

Adult↗