| Project/Area Number |
08672135
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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 |
Functional basic dentistry
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| Research Institution | Osaka Prefecture University |
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Principal Investigator |
OGAWA Kozo Osaka Prefecture University, Research Institute for Advanced Science and Technology, Professor, 先端科学研究所, 教授 (60100187)
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| Project Period (FY) |
1996 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1998: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1997: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1996: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | dental caries / Streprococcus sobrinus / hydroxyapatite / cariogenic α-glucan / lactic acid / (1→3)-α-D-glucan / X-ray diffraction analysis / conformational energy calculation / Streptococcus sobrinus / ハイドロオキシアパタイト / 乳酸 / カルボキシメチルキチン / エチレングリコールキチン / α-Glucan / Hydroxyapatite / Phenylalanine / 卵白アルブミン / 赤外吸収スペクトル / 蛍光標識 / 蛍光測定 / Streptococcus Salivarius / α-1,3-Glucan / エチレングリコールキトサン / X線回析繊維図形 / コンホメーション解析 |
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| Research Abstract |
It has been known that a bacteria, Streptococcus sobrinus, found in human saliva converts sucrose to a sticky polysaccharide called α-glucan. This glucan called α-glucan is composed of (1→3)-α-linked D-glucose in the backbone sequence on which (1→6)-α-linked D-glucose is attached as a side residue, and it is involved in dental plaque formation by sticking on the surface (tooth enamel composed of hydroxyapatite) of human teeth. In the plaque, the bacteria transforms sucrose to lactic acid which dissolves hydroxyapatite (decalcification of the enamel) and, consequently it causes of dental caries. We have studied to analyze the cause of dental caries by various physicochemical strategies as follows.
1. The conformational analyses of α-glucan by using an X-ray diffraction coupled with an energy calculation indicated that the backbone (1→3)-α-D-glucan takes up an extended two-fold helix (a zigzag structure). Some energetically preferable conformations of the glucan were proposed.
2. Spectroscopic (infrared, fluorescence and circular dichroism) studies on the interaction between α-glucan and a hydroxyapatite crystal of pseudohexagonal polymorph, which is likened to tooth enamel, did not detect the presence of any strong bond such as hydrogen bonding.
3. Examinations of the effects of some caries preventers on the dissolution of hydroxyapatite to lactic acid indicated that two chitin derivatives (carboxymethyl and ethylene glycol chitins) decrease the soubility.
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