Tsutomu Shimono

Metabolic and energetic aspects of the growth response of Streptococcus rattus to environmental acidification in anaerobic continuous culture

Streptococcus rattus, a serotype b strain of mutans streptococci, was grown in an anaerobic glucose-limited chemostat. The molar growth yield of glucose [Yglucose, g dry wt (mol glucose)-1] together with the maximum growth yields (Ymax) and maintenance coefficients for glucose utilization and calculated ATP generation were estimated as a function of pH. When the pH was lowered from 7.0 to 5.0, Yglucose decreased, with a concomitant gradual change in the composition of the end product from a mixture of formate, acetate and ethanol to one mostly of lactate. Whereas the Ymax for glucose decreased without any change in the Ymax for ATP on acidification, both of the maintenance coefficients markedly increased. Kinetic and immunochemical examinations indicated the presence of an F1F0-type proton-translocating ATPase in the membrane fraction prepared from bacterial cells grown under acidic conditions; no detectable level of the enzyme was found in cells grown at neutral pH. However, when incubated with glucose under non-growing conditions, these acid-adapted and unadapted cells showed an insignificant difference in the ability to maintain the intracellular pH alkaline relative to the acidic environments. These results suggest that the organism responds and adapts to environmental acidification by sacrificing some energy cost in terms of both the efficiency of glucose utilization to generate ATP and the extra maintenance required to continue biomass production as efficiently as under neutral pH.

Reliability and cross-cultural validity of a Japanese version of the Dental Fear Survey

BackgroundThis study established the reliability and cross-cultural validity of a Japanese version of the Dental Fear Survey (DFS).MethodsTwo studies were carried out in separate populations. The first involved 166 Japanese dental and nursing students and assessed internal consistency and test-retest reliability. The second involved 2,095 Japanese parents or guardians of school children and tested the hypothesis that the conceptual structure of the Japanese translation was consistent with the U.S. version using Structural Equation Modeling (SEM).ResultsIn the first study Cronbach alpha ranged from .94 to .96 and test-retest reliability (Spearman correlation) ranged from .89 to .92. The intra-class correlation coefficients (ICC) was 0.919 (95%CI: 0.892 – 0.940). In the second study SEM was used on the covariance matrix of the 20 questions in a random sample of 600 questionnaires to evaluate the goodness of fit of the theoretical model; and then, in an exploratory manner corrected for specification errors until a model that fit the data well was achieved.ConclusionThe Japanese version of the DFS appears reliable and demonstrates cross-cultural validity. The modeling confirms the three factors on which the English language version was based.

Cariogenic Bacteria and Caries Risk in Elderly Japanese Aged 80 and Older with at Least 20 Teeth

OBJECTIVES: To assess caries risk and check the presence of four commonly found oral cariogenic bacteria in “8020” achievers.

The relationship between body balance and occlusal balance of Japanese children during the deciduous dentition period

Abstract The relationship between childrens deciduous dentition occlusal balance and bodys gravity center movement was studied. The participants of this study were 128 children with Hellmans Dental Age IIA stage at a nursery school. The distance and the area of gravity center movement (GCM) when the participants had their eyes-opened and eyes-closed were measured with automatic posture analytical devices. Occlusal abilities including occlusal contact area, average pressure, maximum occlusal pressure, occlusal force and occlusal balance were measured with the Dental Prescale® system. Analysis of occlusal balance was determined by separating the middle group (|x|≤5mm) from the deflection group (|x|>5 mm) based on the position of occlusal balance center. A significant difference was found between the occlusal balance of the middle group (n=96) and the occlusal balance of the deflection group (n=32) in the distance and area of gravity center movement with eyes-opened and closed. The distance and area of gravity center movement of the middle group was less than that of the deflection group. Analysis of body balance was determined by the good balance group and bad balance group based on the GCM area with eyes-closed. A difference was found between the good balance group and the bad balance group in the occlusal contact area and occlusal force. The occlusal contact area and occlusal force of good balance group were higher than the bad balance group. Body and occlusal balance was observed to have some interactive influence during Hellmans Dental Age IIA period. The influence of occlusal balance on body balance is much stronger and obvious than the influence of body balance over occlusal balance. Occlusal balance can influence on the body balance most of the time while body balance can sometimes influence on the occlusal balance.

Risk behaviors and its association with caries activity and dental caries in Japanese children

Abstract The aim of this study was to assess risk behaviors and its association with caries activity and dental caries in Japanese children. The subjects were 392 young Japanese children who underwent dental health check-up at 18, 30 and 42 months of age. Oral examinations, Cariostat tests and dental health questionnaires were carried out at each time. The caries prevalence of children was 1.5% at 18 months, 9.9% at 30 months and 28.1% at 42 months. Caries activity based on the Cariostat scores of children was correlated with caries status (caries-free/carious) at 42 months. In children with caries during each examination period at 42 months, eating snacks while playing was ranked as the most important behavioral risk ( P P P P P P P

Viability of the Cariostat® medium as a source of DNA for further analysis through polymerase chain reaction

Abstract This simulation study was carried out to analyze and evaluate Cariostat-inoculated samples through a conventional PCR protocol specific for Streptococcus mutans strains and also for the purpose of establishing acceptable storage conditions for Cariostat-inoculated samples in cases in which optimal storage conditions are not feasible. A reference strain of Streptococcus mutans (ATCC 25175) was used in the study. The samples were subjected to different inoculation, incubation and storage conditions, and bacterial viability was checked through a conventional PCR technique and by assessment of colony growth on different agar media. Band detection of all samples incubated for even up to 120 hours at 37°C was still possible, indicating less DNA degradation. Samples stored at −20°C yielded results closest to those of samples incubated normally (without storage), followed by samples stored at 4°C and then samples stored at room temperature. The difference in these results, however did not influence the quality of DNA to an unsatisfactory level. For bacterial viability through agar plating, even if there were no more viable growth on the plates, band detection from strains inoculated and stored in Cariostat was still possible. From these results, we conclude that samples stored under various conditions can be further analyzed using DNA extraction protocols for conventional qualitative PCR amplification.

Presence of Streptococcus mutans or Streptococcus sobrinus in Cariostat®-inoculated plaque samples from Japanese mother-child pairs

Abstract The aim of this study was to determine the presence of Streptococcus mutans or Streptococcus sobrinus in Cariostat-inoculated plaque samples obtained from Japanese mother-child pairs through a conventional PCR technique and to establish the presence of these bacteria and caries risk. Oral examination and caries risk assessment using the Cariostat ® were carried out on 168 children, aged 6–31 months, and their mothers. The presence of S. mutans and S. sobrinus in Cariostat-inoculated plaque samples was checked through PCR and tested for relevance with caries risk. A significant correlation ( P S. mutans or S. sobrinus in plaque samples from their children in the 19–31-month-old age range. However, no significant relationship found between the presence of either strain in the plaque of younger children (6–18 months) and caries risk of mothers. Likewise, high caries risk was seen in 49.1% of the 19–31-month-old children of highrisk mothers ( P P S. mutans and S. sobrinus in plaque samples obtained from mothers and their children through conventional PCR techniques.

In vitro antibacterial activities of Scutellaria baicalensis Georgi against cariogenic bacterial

Abstract Scutellaria baicalensis Georgi has been used for thousands of years in traditional Chinese medicine practice for several purposes. It possesses several biological activities such as anti-oxidative, anti-inflammatory, antibacterial and antiviral activities. Although the antibacterial activity of Scutellaria baicalensis Georgi has already been demonstrated, little is known about its antibacterial activity against oral pathogens in vitro . Therefore, the aim of this study is to evaluate the antibacterial activity by six different kinds of Scutellaria baicalensis Georgi extracts in vitro . The three kinds of bacterial strains were used as follows: Streptococcus mutans ATCC 25175, Streptococcus sobrinus ATCC 33478 and Streptococcus salivarius ATCC 7073. The antibacterial activity was determined by the agar diffusion method, and the zones of growth inhibition were measured. The MICs and MBCs were determined by the broth dilution and agar dilution methods. The bactericidal activity was determined by time-kill assay. In all the Scutellaria baicalensis Georgi solvent extracts, except for water and ethyl acetate, a significant inhibitory activity was observed. The acetone and 80% ethanol, and the ethanolic extracts showed higher activity than the methanol extracts and produced inhibition zones ranging from 7.11±0.18 to 14.79±1.02mm in diameter at a concentration of 750μg/disk. The MIC value of the Scutellaria baicalensis Georgi extracts ranged from 125 to 1,000μg/m l . The MBC values for different strains and extracts ranged from 250 to 2,000μg/m l . Thus, Scutellaria baicalensis Georgi would be useful for the suppression of oral pathogens, and has the potential for use in the prevention of dental caries.

Risk behaviors and their association with presence of S.mutans or S.sobrinus and caries activity in 18-month-old Japanese children

Abstract The purpose of this study was to investigate risk behaviors associated with the presence of S. mutans or S. sobrinus and caries activity. The subjects were 448 mother-child pairs who underwent dental health examinations between February 2004 and November 2004 when the children were 18 months old. Caries activity was assessed by the Cariostat test. The presence of S. mutans and S. sobrinus was detected using PCR techniques. Questionnaires regarding risk behaviors were completed by the mothers. A statistically significant correlation was found for the detection of S. mutans and/or S. sobrinus in children and mothers ( P P P P P P P P P

Comparison of the hand disinfectant effects between super hypochlorous water and 7.5% povidone-iodine

The objective of this study was to compare the hand disinfectant effects between super hypochlorous water and 7.5% povidone-iodine. Subjects included thirty pediatric dentists. They first watched the educational videotape for hand disinfection. They then pressed their right five fingers on Brain Heart Infusion (BHI) agars. They disinfected their hands under running super hypochlorous water until they considered to be enough clean, removed the excess water using a paper towel and again pressed their fingers on the BHI agars. Furthermore, the individual disinfectant time was measured. The agars were incubated at 37°C for 48 h, the colonies counted and calculated as logarithmic values. The same procedures were performed using 75% povidone- iodine two months later. As results, the following observations were shown. The disinfectant effects of super hypochlorous water were significantly more effective than that of 7.5% povidone-iodine. There was no correlation between disinfectant effects of both disinfectants and the hand disinfecting times.