Hiroo Tamagawa

Relationship between Enzyme Activities Involved in Oxygen Metabolism and Oxygen Tolerance in Black-pigmented Bacteroides

In this study, the relationship between enzyme activities involved in oxygen metabolism and the degrees of oxygen tolerance in black-pigmented Bacteroides was investigated. All strains of Bacteroides tested possessed the activities of NADH oxidase and superoxide dismutase, whereas the activities of catalase and peroxidases were not detected in the cell-free extracts. There were relatively high correlations between ozygen tolerance and activity of either NADH oxidase or superoxide dismutase. The activity of superoxide dismutase showed a higher correlation with oxygen tolerance than with that of NADH oxidase. Among the species tested, Bacteroides gingivalis showed the highest activities of both the enzymes and was the most tolerant in the presence of oxygen. Furthermore, the activities of these two enzymes increased during aeration of the oxygen-tolerant strain Bacteroides gingivalis 381, but not in the oxygen-sensitive strain Bacteroides denticola ATCC 33185. These results suggest that superoxide dismutase and NADH oxidase might be important for protection of black-pigmented Bacteroides against the toxic effect of oxygen.

Effect of Transferrin on the Growth of Porphyromonas gingivalis

This study describes the effect of transferrin as an iron source on the growth of Porphyromonas (formally Bacteroides) gingivalis. Bacterial growth was monitored spectrophotometrically. All strains of P. gingivalis tested grew well in medium containing transferrin. The growth of P. gingivalis depended not only on the concentration of transferrin, but also on the iron saturation level of the protein. However, growth was not stimulated with either the ferrous or ferric iron salts tested. The addition of dipyridyl to the medium containing transferrin suppressed the growth of P. gingivalis, which also did not show species-specificity for human transferrin. Transferrin-binding activity was found in P. gingivalis by solid-phase assay with peroxidase-conjugated human transferrin. These results suggest that P. gingivalis may be capable of utilizing transferrin as an iron source for growth in vivo.

Association of Tooth Loss with Psychosocial Factors in Male Japanese Employees

Association of Tooth Loss with Psychosocial Factors in Male Japanese Employees: Naoji Hayashi, et al. Department of Preventive Dentistry, Graduate School of Dentistry, Osaka University—It would seem that good psychosocial conditions would have a positive effect on oral health, but few data exist regarding the association of psychosocial factors with tooth loss. The association between psychosocial factors and tooth loss was studied in male industrial workers in Japan. In an annual health checkup, tooth loss status was assessed by oral examination in 252 workers (age 2059 yr). Information pertaining to psychosocial factors, lifestyle and oral health behavior was also obtained through a self‐administered questionnaire. The mean tooth loss per worker showed a significant increasing trend with age. Mean tooth loss was 0.32 in the 20‐29‐yr‐old group, 0.82 in the 30‐39‐yr‐old group, 1.28 in the 40‐49‐yr‐old group and 2.91 in the 50‐59‐yr‐old group. Bivariate analyses revealed that age (P<0.01) and alexithymia (P<0.05) were significantly associated with tooth loss. In contrast, work stress, depression, type A behavior, job‐ and life‐satisfaction were not significantly associated with tooth loss. In multivariate analyses, the associations of age (P<0.02) and alexithymia (P<0.05) remained statistically significant after adjustment for oral health behavior and lifestyle variables. We suggest that an alexithymic personality may affect tooth loss status in male employees.

Changes in Oxygen Consumption in Dog Gingiva during Induction of Experimental Periodontitis

The purpose of this study was to examine changes in oxygen consumption in dog gingiva during induction of experimental periodontitis. The disease was induced in adult mongrel dogs during a 16-week period by placement of silk ligatures around selected teeth. The oxygen consumption rate of gingival tissue was determined in vivo by a non-invasive technique, tissue reflectance spectrophotometry. Changes in such clinical parameters as gingival index, plaque index, pocket depth, attachment level, and gingival crevicular fluid flow indicated acute inflammatory responses during the first three weeks after ligation, followed by the appearance of chronic inflammation during the remaining 13 weeks. The oxygen consumption rate increased during the first seven days after ligation and stayed near the maximum level for 2-7 weeks; this was followed by a gradual decrease during the final nine weeks. These results suggest that gingival oxygen consumption increases rapidly with the increase of acute inflammation responses and then decreases slightly with the gradual development of chronic inflammation. Positive correlations were observed between the oxygen consumption rate and other clinical indices. Thus, the tissue reflectance spectrophotometry is a new, useful method for objective, quantitative, and non-invasive assessment of gingival oxygen consumption.

Integration of computational fluid dynamics and computational aero acoustics on grid for dental applications

The hybrid applications are needed in dental research because the result of their operation could be predicted by both modeling of an oral truct and more than two kind of physical simulations. However, it takes long time to perform the hybrid applications, cost a lot of money and needs some experience to deal with them. This paper proposes a new execution procedure of two applications which can reduce the implementation time by considering parallel efficiency of those applications. It can determine which attitude should be taken, sequential or separate execution of two different applications related with each other. Following the execution procedure, the dental hybrid application was performed. As a result of that, desirable pairs of the number of CPUs allocated to each simulation could be found. This means that the adequate procedure should be considered before execution of the hybrid applications, in order to play a compute power producer for dental clinics and hospitals.

Evaluating tooth brushing performance with smartphone sound data

This paper presents a new method for evaluating tooth brushing performance using audio collected from a smartphone. To do this, we use hidden Markov models (HMMs) to recognize audio data that include various types of tooth brushing actions, such as brushing the outer surface of the front teeth and brushing the inner surface of the back teeth. We then use the output of the HMMs to build regression models to estimate tooth brushing performance scores, such as stroke quality of brushing for the back inner teeth and duration of brushing for the front teeth. The scores used to train these regression models are obtained from a dentist who specializes in dental care instruction, with the resulting regression models estimating performance scores that closely correspond to the scores assigned by the dentist.

The effect of wearing custom-made mouthguards on the aeroacoustic properties of Japanese sibilant /s/

BACKGROUND/AIM There have been many reports on the discomfort of speech when wearing oral appliances. Fricatives articulated in an oral cavity can be difficult to pronounce when oral appliances are worn, because the oral cavity is partially changed by their installation. Sibilant /s/, one fricative, is especially difficult to pronounce when wearing oral appliances. This study investigates the effect of the difference in the setting positions of the palatal margin of custom-made mouthguards on the aeroacoustic characteristics of sibilant /s/. MATERIALS AND METHODS Eighteen subjects (11 women and seven men) participated. The palatal margin of mouthguards was set at the gingival line for nine subjects and 4 mm from the line for another nine subjects. Acoustical analyses examined the difference of the palatal margins of the mouthguards on the autocorrelation coefficient, the zero crossing count, and the spectral peaks of sibilant /s/. RESULTS The results showed that the zero crossing count of the waveforms and the spectral peaks of sibilant /s/ were significantly broadened and shifted toward the low-frequency range with the mouthguard whose palatal margin extended 4 mm from the gingival line than the mouthguard whose palatal margin was set at the gingival line. CONCLUSION We believe that a more appropriate palatal mouthguard design for custom-made mouthguards can be made by considering the aeroacoustical effects. Our study supported the mouthguard whose palatal margin was set at the gingival line by considering the influence on pronouncing sibilant /s/. We believe that a more appropriate palatal mouthguard design for custom-made mouthguards can be made based on the balance of aeroacoustical effects and mechanical requirements.

Purification and Some Properties of Fucosyltransferase in Human Parotid Saliva

Fucosyltransferase was purified from human parotid saliva by affinity chromatography on GDP-hexanolamine Sepharose, followed by chromatofocusing on PBE 94 exchanger gel. The purified enzyme had the N-acetylglucosaminide α1→4, the N-acetylglucosaminide α1→3, and the glucoside α1→3 fucosyltransferase activities. The molecular weight of the purified enzyme was estimated to be approximately 20,000. These enzyme activities showed identical pH and divalent metal ion dependencies and identical rates of inactivation upon being heated. The paper chromatographic analysis of the fucosylated products by the purified enzyme and the susceptibility of these products to linkage-specific fucosidase digestion indicated that the transferase formed the Fuc α1→4GlcNAc, Fuc α1→3GlcNAc, and Fuc α1→3Glc linkages.

Computational oral and speech science on e-science infrastructures

We demonstrate an oral scientific simulation and its visualization based on E-science. This oral scientific application will become an essential key component for medical and dental clinic in the near future because Bio-Medical simulations will provide a clinical index considering a prognostic of a disease. In this case, it was shown that the physical theory of sound production of speech sound, sibilant. However, it is difficult to acquire the computational and storage resources in the hospitals. Our E-science infrastructure enables scientists and clinicians to achieve the advanced information produced by simulations. As the result of this phase implementation for Bio-Medical simulation on E-science infrastructure, we could extract the scientific findings about the oral science. Moreover, this infrastructure can be used more generally because of the divided architecture between applications and E-science infrastructure.

The Presence of Fucosyltransferases with Different Substrate Specificity in Human Parotid Saliva

Using glycoproteins and milk oligosaccharides as substrate acceptors, we demonstrated at leaet two fucosyltransferases in human parotid saliva. One enzyme transferred L-fucose from GDP-fucose to the C-3 position of N-acetylglucosamine or glucose residue of oligosaccharide chains, and the other transferred to the C-4 position of N-acetylglucosamine residue of oligosaccharide chains.