| Co-Investigator(Kenkyū-buntansha) |
YAMAZAKI Tomomi National Institute of Public Health, Department of Nutrition and Biochemistry, Senior Researcher, 栄養生化学部, 主任研究官 (00218439)
ICHIJYO Hidenori Tokyo Medical and Dental University, Graduate School Professor, 大学院・医歯学総合研究科, 教授 (00242206)
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| Budget Amount *help |
¥13,500,000 (Direct Cost: ¥13,500,000)
Fiscal Year 2000: ¥6,700,000 (Direct Cost: ¥6,700,000)
Fiscal Year 1999: ¥6,800,000 (Direct Cost: ¥6,800,000)
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| Research Abstract |
Recently, public problems concernig endocrine disruptors have been increasing. One of endocrine disruptors, bisphenol A(BPA)is a raw material that synthesizes Bis-GMA which is used as dental materials such as fissure sealants, composite resins and bondings as well as that does polycarbonate which is used as dental materials such as orthodontic bracket, temporary crown and teeth resins. In dental field, there are necessary to evaluate safety of chemical substances in polymer materials and it is urgent to clarify the residual BPA in dental materials, to analyze the elution pattern of BPA from it and to develop the sensitive detection system of endocrine disrupors. The purpose of the present study was to clarify whether endocrine disruptors such as BPA were leached from dental materials and to develop the elution testing of dental materials as well as to clarify the changes in genes elicited by BPA-treatment using breast cancer cell lines. Levels of leachable BPA from polymerized material
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s such as fissure sealants, composite resins and bondings immersed in artificial saliva was under detection limit(0.5ng/mL, namely 5.7-15.8ng BPA/g resin)using a high-performance liquid chromatograpy with a fluorescent detector. On the other hand, leachable BPA was detected from orthodontic brackets, temporary crowns and resin teeth immersed in artificial saliva. Furthermore, levels of leaching BPA and p-t-butylphenol(t-BuP)from orthodontic brackets immersed in human saliva was more inreasing than those of orthodontic brackets immersed in artificial saliva. Residual BPA and t-BuP immersed in human saliva was increased compared to controls. These results indicate that human saliva should be used as the immersion solvent for the elution testing of polymers to reflect the simulated oral environment. In conventional cell proliferation methods to evaluate the estrogenecity of the endocrine disruptors, MCF-7 was used. However, as this cell line was transformed during cell culture, T47D cell line, breast cancer cell line, was used. This cell was well reproduced and highly sensitve compared to MCS-7. mRNA was extracted from this cell treated BPA for 24 hours and then differential display was performed. Examining increased cDNA of expression, NADH dehydrogenase subtype was greatly increased after BPA treatment for 24 hours. Less
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