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Biomedical subjects

T Horikawa

Publications and source records attributed to T Horikawa.

At least 91 records · Page 5Linked to original sources
PubMed1981

Immunosuppressive action of oral Streptococci.

The study on the immunosuppressive activity of the cytoplasmic component (SF) from Streptococcus mitis on the immune response of mice to the sheep red blood cells (SRBC) was carried out. The bacterial cell suspension was disrupted in a Braun shaker. The disrupted cell suspension was diluted and centrifuged at 10,000 x g for 30 minutes to remove the cell walls. The supernatant was centrifuged at 31,000 x g for 45 minutes and the final supernatant was dialyzed against distilled water, frozen and lyophilized. These products were employed as the cytoplasmic component (SF). The SF in the extracts of Streptococcus mitis suppresses the antibody formation in mice against SRBC. It is effective to inject it just one day before the inoculation with SRBC.

Animals↗
PubMed1981

A preliminary study on isolation and enumeration of mycoplasmas in dental plaques: the effect of sonication on viability of oral mycoplasmas.

The effect of sonication on the viability of Mycoplasma salivarium and Mycoplasma orale was examined as a preliminary investigation on the quantitative studies on mycoplasmas in the dental plaques. Mycoplasma cell aggregations suspended in PBS or liquid medium were sonicated and the samples were removed at 5-second intervals for 20 seconds to check the viable counts. Inactivation of the mycoplasmas was almost directly proportional to the sonication time. M. orale was more sensitive to sonication than M. salivarium. Mycoplasmas were damaged more readily in PBS than in the liquid medium. Dental plaques suspended in PBS were also sonicated exactly as mentioned above. The number of mycoplasmas in the dental plaques (1 mg) ranged from 1.09 x 10(2) to 1.75 x 10(5) cfu. The desirable sonication time to prepare the homogeneous suspensions of dental plaques was concluded to be 5 seconds.

Dental Plaque↗
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↗
PubMed1979

Biological activity of secretory IgA--comparison of agglutinating specificity with SIgA and Ca++-dependent agglutinin--.

Ca++-dependent bacterial agglutinin was isolated from the human parotid saliva by gel filtration of Sepharose 2B. The agglutinin appeared in the void volume fractions. Treatment of this agglutinin with EDTA resulted in the loss of its ability to agglutinate the bacteria. Standardized solutions of the agglutinin were tested for the agglutinating activity against 18 strains of oral indigenous bacteria. It was found that the agglutinin exhibited varying degrees of activity to all the test strains and the activity was generally higher than that of secretory IgA. It was also found that the receptor sites of the Ca++-dependent agglutinin for Str. sanguis and Str. mitis were identical whereas SIgA contained a number of available binding sites, for different bacterial species.

Adult↗
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

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↗