Biomedical subjects

Akira Koyama

Publications and source records attributed to Akira Koyama.

4 recordsLinked to original sources

PubMed2006

Identification of two subpopulations of Bacillus Calmette-Guérin (BCG) Tokyo172 substrain with different RD16 regions.

Two types of colonies with different morphologies (smooth: S and rough: R) formed when Bacillus Calmette-Guérin (BCG) Tokyo172 substrain was cultured on Middlebrook 7H10 agar medium, and their genotypes were analyzed by multiplex PCR on five RD regions and SenX3-RegX3. In most cases these two colony types had different genotypes, i.e., S colonies showed a characteristic 22 bp deletion in Rv3405c of the RD16 region (type I), and R colonies did not have this deletion (type II) similar to many other BCG substrains. Thus, there was a strong relationship between colony morphology and genotype. Both genotypes were found in every Tokyo172 preparation tested, including the seed lot for production, the origin of seed lot from the 1960s and ATCC BCG Japan. Type I was always in the majority. It was suggested that types I and II constituted independent subpopulations within the Tokyo172 substrain. Type I was shown to have a growth advantage over type II both on culture media and in mice organs.

Animals↗

PubMed2005

Modified multiplex PCR for identification of Bacillus Calmette-Guérin substrain Tokyo among clinical isolates.

When an adverse reaction occurs and a mycobacterial species is isolated from a person vaccinated with Bacillus Calmette-Guérin (BCG) or a patient receiving BCG immunotherapy, it is essential to identify whether the isolate is BCG or another mycobacterial species. However, differentiation of BCG from other members of Mycobacterium tuberculosis complex has been very difficult. Using several specific primer-pairs, Bedwell et al. [Bedwell J, Kairo SK, Behr MA, Bygraves JA. Identification of substrains of BCG vaccine using multiplex PCR. Vaccine 2001; 19: 2146-51] recently reported that they could distinguish BCG substrains. We modified their method to improve differentiation of Tokyo 172 from other members of the M. tuberculosis complex, and examined whether this modified method could be applied to clinical isolates. Our method clearly identified BCG substrain (BCG Tokyo 172) among clinical isolates and easily distinguished between M. tuberculosis and wild-type Mycobacterium bovis.

Adjuvants, Immunologic↗

PubMed2005

Bacillus calmette-guerin Tokyo172 substrain for superficial bladder cancer: characterization and antitumor effect.

PURPOSE: We investigated the preparation of bacillus Calmette-Guerin (BCG) Tokyo172 substrain (Japan BCG Laboratory, Ltd., Tokyo, Japan) on the characteristics of bacilli and antitumor activity in a mouse model in comparison with a preparation of the Connaught substrain (Aventis Pasteur, Ltd., Toronto, Ontario, Canada). MATERIALS AND METHODS: Lyophilized BCG preparations of Tokyo172 and Connaught for superficial bladder cancer were tested. The number of bacilli and cfu per dose, dispersion, size and attachment to murine bladder tumor cells were determined after reconstitution. Antitumor activity was assessed by intradermal injection of tumor cells with various doses of either BCG preparation into the flanks of syngeneic mice, followed by the observation of tumor suppression and survival in mice. RESULTS: Each dose of Tokyo172 had about half the bacilli in a dose of Connaught but the cfu content was about 13-fold higher for Tokyo172 than for Connaught. After reconstitution Tokyo172 bacilli were better dispersed with fewer aggregates than Connaught bacilli. Tokyo172 bacilli were about half as long as Connaught bacilli and Tokyo172 bacilli showed better attachment to tumor cells in vitro. In mice Tokyo172 achieved similar tumor suppression at a lower dose than Connaught. CONCLUSIONS: High viability, good dispersion and efficient binding to tumor cells by BCG bacilli in the Tokyo172 preparation seem to be the main reasons for the lower clinical dose of this preparation compared with the Connaught preparation (18 vs 81 mg dry weight).

Animals↗

PubMed2002

Molecular dynamics simulation of polymer crystallization from an oriented amorphous state.

The molecular process of crystallization from an oriented amorphous state was reproduced by molecular dynamics simulation for a realistic polyethylene model. The initial oriented amorphous state was obtained by uniaxially drawing an isotropic glassy state at 100 K. By the temperature jump from 100 K to 330 K, there occurred crystallization into the fiber structure, during the process of which we observed the developments of various order parameters. The real-space image and its Fourier transform revealed that a hexagonally ordered domain was initially formed, and then a highly ordered crystalline state with stacked lamellas developed after further adjustment of the relative heights of the chains along their axes.

Journal Article↗