| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1997: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1996: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1995: ¥600,000 (Direct Cost: ¥600,000)
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| Research Abstract |
The mouths of most people become infected by mutans streptococci (Streptococuus mutans and Streptococcus sobrinus) eary in Life. Infants acquire this pathogen from infected individuals, such as their parents, with whom they have frequent contact. Mutans streptococci firmly adheres to tooth surfaces with the function of glucan. The Mixture of mutans streptococci and glucan formed pathogenic biofilm. Within the biofilm, mutans streptococci produces considerable amount of organic acids, such as lactic acids, acetic acid and formic acid. F_1F_0ATPase of this bacteria excrete proton outside the cell to survive in the acidic environment. Therefore, pH inside the biofilm gradually going down.
Genes of the S.mutans F_1F_0ATPase beta-subunit was amplified and cloned. Then, we made the F_1F_0ATPase beta-subunit defective mutant which was designated S.mutans NTS1. Turbidity of the culture fluid of NTS1 strain was fall below parent strain GS5. F_1F_0 enzyme activity of NTS1 strain decreased to 47% of that of GS5. Relatively long lag phase was observed until logarithm period in the growth curve of NTSS1 strain compared with GS5. In the presence of gramicidin D, an ionophoric antibiotic which renders the cytoplasmic membrane permeable to proton, decreased the growth rate of mutans streptococci. Thre times long lag phase was observed in the growth curve of NTS1 with gramicidin D compared with the growth curve without gramicidin D.
In other experiments, we found some chandidates of peptide anti-caries vaccine, which were synthetic peptides derived from the PAC molecule. We also identified GTF inhibitors, which were synthetic peptides derived from the region responsible for GTF activity.
Our data suggest that F_1F_0ATPase inhibitors, PAc anti-caries vaccine and GTF inhibitors are promising as a new medicine of caries prevention.
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