| Project/Area Number |
16591843
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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 |
Morphological basic dentistry
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| Research Institution | The Nippon Dental University |
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Principal Investigator |
AOKI Shigeji The Nippon Dental University, School of Dentistry at Niigata, Professor, 新潟生命歯学部, 教授 (20095045)
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| Co-Investigator(Kenkyū-buntansha) |
KUWA Shoko The Nippon Dental University, School of Dentistry at Niigata, Associate Professor, 新潟生命歯学部, 助教授 (40095063)
NAKAMURA Kenjirou The Nippon Dental University, School of Dentistry at Niigata, Associate Professor, 新潟生命歯学部, 助教授 (00227894)
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| Project Period (FY) |
2004 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2006: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 2005: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2004: ¥800,000 (Direct Cost: ¥800,000)
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| Keywords | Candida albicans / Antifimgal drugs / Reactive oxygen species (ROS) / Oxidative damage / Amphotericin B / 病原性真菌 |
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| Research Abstract |
This study aimed to examine the involvement of oxidative damage in antifungal drugs against the pathogenic yeast Candida albicans. Both a wild-type, respiration-competent parental strain (K) and a respiration-deficient (petite) mutant (KRD-19) were used. The production of reactive oxygen species (ROS) from Candida cells was measured using methyl-Cypridina-luciferin analog (MCLA) or dichlorodihydrofluorescein diacetate (H2DCF-DA). ROS generation from the parent strain K was strongly stimulated by paraquat (PQ) while PQ failed to produce ROS in the respiration-deficient mutant KRD-19. Thus, the use of the parent and respiration-deficient strains, in combination with PQ, was suitable to examine roles of the ROS in antifungal agents.
An enhancing effect of PQ on antifungals was most evident with amphotericin B (AmB), compared with four azoles. Thus, the effect of PQ on AmB was examined extensively. In the parent strain, the minimal inhibitory concentration (MIC) of AmB, 0.25 μg/ml, tested with a liquid culture was lowered to 0.025μg/ml by 1 mM PQ. Such a PQ-induced decrease in the MIC value of AmB was minimal with the respiration-deficient mutant. Similar PQ-induced enhancement of AmB activity toward the parent strain was also observed with growth on an agar medium. Exogenous SOD and catalase failed to diminish the enhancing effect of PQ on the growth inhibitory activity of AmB in the parent strain, suggesting an interaction between superoxide radical and AmB in Candida cells. Leakage tests with radioactive leucine showed that PQ did not enhance damage of cellular membranes by AmB. The enhancement of AmB activity by PQ in wild-type parent strain can be explained by extensive superoxide generation depending on respiration. Such an enhancing effect of PQ was weak with four azoles tested.
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