Kyushu University Academic Staff Educational and Research Activities Database
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Yoshihisa Yamashita Last modified date:2018.06.22

Professor / Division of Oral Health, Growth and Development
Department of Dental Science
Faculty of Dental Science


Graduate School
Undergraduate School


Homepage
http://www.prevent-dent-kyushu-u.com/
Home page of Section of Preventive and Public Health Dentistry .
Phone
092-642-6350
Fax
092-642-6354
Academic Degree
Ph. D. in Dentistry
Field of Specialization
Preventive Dentistry
Outline Activities
Research activities
・Study of structure and fuction of vilurence factors of cariogenic bacteria
・Development of preventive measures of dental caries against virulence factors
・Study of structure and fuction of vilurence factors of periodontopathic bacteria
・Development of preventive measures of periodontal diseases against virulence factors
・Study of relationship between periotonal diseases and general health
・Study of relationship between oral bacteria and oral health
・Study of cause of halitosis and developmet of preventive measures of halitosis

Educational activities
・Lecutre on and practice in preventive dentistry and social dentistry to udnergraduate students
・Clinical practice in preventive dentitry to udnergraduate students
・Clinical education on preventive dentistry to interns and postgraduate students
・Education on preventive dentistry and social dentistry to postgraduate students
・Research instruction on preventive dentistry and social dentistry to postgraduate students

Social acitivties
・Clinical preventive dentitry in Kyushu University Hospital
・Support of community dental health activity in health center
・Support of indutrial dental health activity in corporations
・Leture at regional dental associations
・Activities as a member of the committiee in academic societies
Research
Research Interests
  • Study of biosynthesis pathway and biological function of cell wall polysaccharide of cariogenic bactria
    keyword : cariogenic bacteria, cell wall polysaccharide
    2000.01 Streptococcus mutans are classified into three serotypes (serotypes c, e, and f), on the basis of the antigenic differences in the cell wall polysaccharides. These antigenic polysaccharides are composed of a backbone structure of L-rhamnose polymers and glucose side chains. We have cloned four loci which are related to the RGP synthesis and identified that four genes (rmlA, rmlB, rmlC and rmlD) are directly involved in the synthesis of dTDP-L-rhamnose from dTTP and glucose-1-phosphate and that a gene (gluA) encoding glucose-1-phosphate uridylyltransferase synthesizes UDP-D-glucose from UTP and glucose-1-phosphate. The rgpG gene seems to be involved in the initial step of the RGP synthesis by transferring N-acetylglucosamine-1-phosphate to a lipid carrier. Furthermore, we found genes required for the RGP synthesis in the region downstream of rmlD. These genes are likely pertaining to the polymerization of rhamnan backbone, transport of polymerized RGP across cytoplasmic membrane, and glucose side chain formation. .
  • Epidemiological study of decrease of dental caries in Japanese
    keyword : dental caries, epidemiology, mutans streptococcus
    2000.10 To evaluate the association between decreasing caries prevalence in Japanese preschool children and mutans streptococci infection, the prevalence of caries and salivary mutans streptococci was examined in 1 to 3 year-olds preschool children in 1995 (n = 135) and 2000 (n = 118). The correlation between caries experience (dft) and the salivary mutans streptococci score with low caries prevalence in the later examination (rs = 0.506, p < 0.0001) was comparable with that in 1995 (rs = 0.571, p < 0.0001). The recent decrease in decay in Japan is associated with a reduction in mutans streptococci infection in the deciduous dentition. Mutans streptococci are closely related to caries prevalence in preschool children regardless of caries prevalence..
  • Analysis of autolytic enzyme of cariogenetic bacteria
    keyword : cariogenetic bacteria, autolysis
    2000.01 Autolysins are enzymes capable of degrading bacterial cell walls. Their roles are proposed for these enzymes in wall growth, cell separation, and wall turnover. We cloned an autolysin-encoding gene of Streptococcus mutans. Insertional inactivation of this gene resulted in the loss of autolytic activity. In addition, the inactivated mutant showed the formation of long cell-chains. This gene seems to encode a major autolysin and be involved in cell separation and wall turnover in S. mutans..
  • Study of acid tolerance of cariogenetic bacteria
    keyword : cariogenetic bacteria, acid tolerance
    2003.04 Streptococcus mutans can produce acid from fermentable dietary carbohydrates and initiate demineralization of the tooth surface. The environmental conditions in dental plaque are highly variable, including frequent shifts in pH from above 7.0 to as low as 3.0. S. mutans has the ability to tolerate and grow in low-pH environments. We study the mechanism that S. mutans evolves to survive the pH changes encountered in dental plaque. We found two genes (gluA and dgk) involved in acid resistance in S. mutans. Furthermore, we will characterize the mutants in which gluA and dgk are inactivated, utilizing protemomic analysis with 2D gel electrophoresis in order to find new genes involved in acid tolerance of S. mutans..
  • Study of the relationship between oral and general health and oral flora based on a quantitative classification of oral flora by using comprehesive detemination of oral bacteria.
    keyword : bacterial flora, comprehensive analysis
    2005.04The relationship between oral and general health and oral flora is analyzed based on a quantitative classification of oral flora by using comprehesive detemination of oral bacteria..
Current and Past Project
  • This project is aimed to clarify the effect of periodontitis on general health by using epidemiological studies between periodontitis and stress, biochemical tests of serum, diabetes mellitus and pneumonia. The project may provide EBM for relationship between periodontitis and general health based on EBM.
Academic Activities
Membership in Academic Society
  • Japanese Society of Public Health
  • International Society for Microbial Ecology
  • American Society for Microbiology
Educational
Educational Activities
Educational activities
・Lecture on and practice in preventive dentistry and social dentistry to udnergraduate students
・Lecture on and practice in oral microbiology to udnergraduate students
・Education on preventive and public health dentistry to postgraduate students
・Research instruction on preventive and public health dentistry to postgraduate students
Social
Professional and Outreach Activities
Social acitivties
・Management of clinic of oral malordor in Kyushu University Hospital
・Support of community dental health activity in health center
・Support of indutrial dental health activity in corporations
・Leture at regional dental associations
・Activities as a member of the committiee in academic societies.