Evaluation of mutagenicity and co-mutagenicity of strong static magnetic fields up to 13 Tesla in Escherichia coli deficient in superoxide dismutase.

PURPOSE: To evaluate the biological effects of static magnetic fields (SMFs) up to 13 Tesla (T), with respect to superoxide behavior, by determining the effect on mutagenicity in superoxide dismutase (SOD)-deficient Escherichia coli strain QC774, and its parental strain GC4468. MATERIALS AND METHODS: Experimental strains were exposed to a 5, 10, or 13T SMF for 24 h at 37°C in Luria-Bertani medium. To evaluate mutagenicity after SMF exposure, the mutation frequency in thymine synthesis genes was determined. The effect of exposure to a 5 or 13T SMF on mutagenicity induced by plumbagin was also investigated. RESULTS: No statistically significant differences in the mutation frequency in thymine synthesis genes were observed between SMF-exposed cells and unexposed cells at any of the applied magnetic flux densities. Furthermore, exposure to SMFs up to 13T did not affect mutagenicity induced by plumbagin. CONCLUSION: Exposure to SMFs up to 13T caused neither mutagenicity nor co-mutagenicity in the SOD-deficient E. coli strain QC774 or in its parental strain GC4468, suggesting that exposure to strong SMFs does not affect the behavior of superoxides in these microorganisms.

Distribution and identification of airborne fungi in railway stations in Tokyo, Japan.

OBJECTIVES: The current study was performed to (1) understand the distribution of airborne fungi culturable on dichloran-glycerol agar (DG18) media over a one-year monitoring period, (2) identify the types of airborne fungi collected, and (3) compare and contrast under- and above-ground spaces, in two railway stations in Tokyo, Japan. METHODS: Measurements of airborne fungi were taken at stations A and B located in Tokyo. Station A had under- and above-ground concourses and platforms whereas station B had spaces only above-ground. Airborne fungi at each measurement position were collected with an air sampler on DG18 media. After cultivation of the sample plates, the number of fungi colonies was counted on each agar plate. RESULTS: In station A, the underground platform was characterized as (1) having the highest humidity and (2) a high concentration of airborne fungi, with (3) a high proportion of non-sporulating fungi (NSF) and Aspergillus versicolor. There was a strong positive correlation between the concentrations of airborne particles and fungi in station A. Common aspects of the two stations were (1) that fungi were mostly detected in autumn, and (2) there was no correlation between the humidity and concentration of fungi throughout the year. CONCLUSIONS: The results of this study indicate that the distribution and composition of fungi differ depending on the structure of the station.

[Bibliographic consideration of proper management of radioactive waste on short-lived period nuclides that are used in nuclear medicine].

A rational clearance system for medical radioactive waste has not yet been established in Japan. As Europe and USA's ways, the establishment of DIS that medical radioactive waste what are kept in storage room for more than decided period each nuclide except from regulation of radiation's control. The purpose of this report is to clarify the problems with the establishment of DIS in Japan through a literature review of the experience in Europe and the USA and previous research that has been reported in Japan. To establish the DIS system, the radiation control system in nuclear medicine should be rebuilt and put into effect.