| Project/Area Number |
14570127
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Pathological medical chemistry
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| Research Institution | Osaka City University |
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Principal Investigator |
SATO Eisuke Osaka City University, Medical School, Associate Professor, 大学院・医学研究科, 講師 (60211942)
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| Project Period (FY) |
2002 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2003: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2002: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | Reactive Oxyge Species / nitric oxide / Bacteria / Mutation / NADH oxidase / Nitirite reductase / 遺伝子進化 / 持続感染 / 微生物 / 酵素環境 / 遺伝子変異 |
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| Research Abstract |
Despite the presence of bactericidal factors and activated neutrophils in saliva and the oral cavity, large numbers of bacteria including S.mutans are living in the oral cavity of human subjects. Because oral concentrations of NO and related metabolites are fairly high, we examined the effect of NO and related compounds on the metabolism of E.coli and S.mutans. Unlike E.coli, S.mutans metabolizes molecular oxygen to H_2O_2 and then to H_2O by using two types of NADH oxidases (Nox-1 and 2). Kinetic analysis using chemiluminescence and electron paramagnetic resonance methods revealed that the wild-type but not knock out species of S.mutans lacking Nox-1, 2 and AhpC generated the superoxide radical via Nox-1-dependent pathway. Although NO did not appreciably affect the oxygen consumption by S.mutans, it increased cellular levels of immunoreactive nitrotyrosyl proteins and inhibited their proliferation particularly under low oxygen tensions. Under air atmospheric conditions, however, NO failed to inhibit the proliferation of S.mutans. Moreover, S.mutans was found to generate NO from nitrite. These results indicate that generation of superoxide and NO is critically important for the survival of S.mutans in the oral cavity enriched with bactericidal metabolites and activated neutrophils.
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