In order to investigate the dynamic response of the cervical vertebrae during occlusion, we electronically stimulated both masseter muscles of anesthetized adult Japanese monkeys, and measured the strain in the lamina of the vertebral arch on both sides of each vertebra when the animals were made to occlude on sticks of 3, 7 or l0mm thickness at either the canine or first molar on one side.
     With occlusion on a stick at the working side canine, the second cervical vertebra served as the focal point in preventing the vertebrae from slanting to one side due to occlusion. In the case of occlusion on the working side first molar, the fourth cervical vertebra was the focal point. However, with occlusion at either the canine or first molar on the non-working side, the third and seventh cervical vertebrae, respectively, served as the focal points.
     With occlusion on a stick at the canine, the upper portion of each cervical vertebra was compressed while the lower portion was under tension. In addition, there was a tendency for the central region on the working side to expand while the non-working side contracted to balance out the distortions in the upper and lower portions. In contrast, with occlusion on a stick at the first molar, there was tension along the body axis on the working side in virtually all regions of the cervical vertebrae; on the non-working side most of the cervical vertebrae showed tension in the horizontal direction. These effects were greater the larger the opening of the mouth.
     A tendency was observed for the stresses to concentration on the non-working side of the sixth cervical vertebra with occlusion at either the canine or the first molar, regardless of the size of the stick. However, because there were a large number of wave forms in the cervical vertebrae that appeared to be dispersing the stresses more than the facial and cranial bones did, it seems that the cervical vertebrae deform in response to their respective position and shape, and ingeniously disperse the stresses.

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     We attempted to isolate hemagglutinins from cells of non-fimbriated Prevotella intermedia strain E18 and to characterize the active fractions.
     Sucrose density ultracentrifugation at 35,000 rpm for 20 h revealed hemagglutination activities in three different fractions (designated A, B and C). Negative staining revealed amorphous structures in fraction A, while vesicle-like structures were a major consti-tuent of fractions B and C. In the API ZYM system, all fractions, as well as whole cells of strain E18, produced alkaline phosphatase, acid phosphatase, phosphoamidase and α-glucosidase. Hemagglutination activity of fraction A was eliminated by heating at 60℃ for l0min, while 70℃ was required for fractions B and C. All fractions were sensitive to trypsin, D-glucosamine, D-galactosamine and N-acetylneuraminic acid. In addition, chymotrypsin, protease type IV and L-arginine caused hemagglutination inhibition in fraction A. The SDS-PAGE pattern of fraction B was similar to that of C, but different from A. However, a protein of approximately 70kDa was common to all Fractions. Scanning and transmission electron microscopy revealed small particles in fraction A, and vesicle-like structures surrounding fractions B and C. Addition of anti-fraction B or C serum caused hemagglutination inhibition in fractions B and C, as well as A. Moreover, the Ouchterlony method revealed common antigens against anti-fractions B and C serum in all fractions. The precipitating lines between fractions A and anti-fraction B and C were located in the center of wells, although the lines between fraction B and anti-fraction B and between fraction C and anti-fraction C, were located on the side of the antigens. Negative staining revealed amorphous structures surrounding vesicle-like structures.
     These results indicate that when amorphous particles, which are glycoprotein in nature, surround vesicle-like structures, they may mediate hemagglutination.

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     We studied antibiotic sensitivity, and the role of β-lactamase activity and outer membrane permeability in the mechanism of β-lactam antibiotic resistance of Capnocytophaga and Prevotella in saliva of children with infantile acute lymphatic leukemia. The 90% minimum inhibitory concentration (MIC₉₀) of imipenem (IPM), cefteram-pivoxil (CFTM-PI), clindamycin (CLDM) and ofloxicin (OFLX) against penicillin G (PCG) resistant Capnocytophaga and Prevotella was 1.56–100μg/ml. The MIC₉₀ of other antibiotics tested was ≥ 200μg/ml. β-Lactamase activity was detected in all strains of both microorganisms. The β-lactamase of Capnocytophaga and Prevotella dissolved ampicillin (ABPC) and cefazolin (CEZ) substrates, respectively. The activity of Capnocytophaga β-lactamase was 7–33mU/mg for ABPC and 22–94mU/mg for CEZ, while these values for Prevotella were 6–149mU/mg for the two substrates. The β-lactamase of both microorganisms dissolved more CEZ substrate than ABPC substrate. The number of isolates was calculated that had both a MIC of ≥ 50μg/ml and β-lactamase activity of ≥ 30mU/mg. The percentage of these isolates was low for IPM and CFTM-PI. However, the percentages were high for other antibiotics tested. Obstruction of outer membrane permeability was observed with ethylendiaminetetraacetic acid disodium salt in the MIC of PCG, CEZ and LMOX in Capnocytophaga, and in the MIC of ABPC and CER in Prevotella.
     These results suggest that multi-resistant isolates of Capnocytophaga and Prevotella were isolated from oral cavities of children with infantile acute lymphatic leukemia, and β-lactamase was closely related to the mechanism of β-lactam antibiotic resistance in these microorganisms.

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     Using electrophoresis, the electron spectroscopy for chemical analysis (ESCA) and the atomic force microscope (AFM), we studied the electrostatic potential, elemental components and ultramicrostructure of the streptococcal surface and investigated the relation between these three elements.
     By measurement of zeta potential, the streptococci were divided into two groups; one consisting of S. cricetus HS-6 and S. rattus BHT, which showed larger zeta potentials and was influenced by pH, and another consisting of S. mutans OMZ 175, S. mutans K-1 and S. sobrinus 6715 which showed smaller zeta potentials and was unaffected by pH.
     ESCA analysis revealed that O, N and C existed on the surface of every streptococci. However P existed only on the surface of the streptococci having larger zeta potentials (S. cricetus HS-6 and S. rattus BHT). This indicates that zeta potentials depend on the surface layer of streptococci.
     Furthermore, bacterial surface observations in water using AFM revealed that S. cricetus HS-6, which is in the larger zeta potential group, showed a rough, needle like surface, while S. sobrinus 6715, which is in the smaller zeta potential group, showed a smoother surface.
     We found it possible to analyze the surface characterization of streptococci by using zeta potential, ESCA and AFM. Furthermore, we concluded that differences in zeta potential of the surface of streptococci depended on the amount of teichoic acid on the surface.

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     We attempted to determine the capability of the atomic force microscope to observe the surface of human dental enamel and to ascertain the effect of saliva adsorption on the ultra-microstructure of the surface. Three types of enamel surface were prepared in this study: 1) Enamel treated with 0.1 M HCl solution for 15 sec; 2) Polished enamel; and 3) Polished enamel placed in saliva for two hours. The atomic force microscope (AFM) and electron spectroscope for chemical analysis (ESCA) were employed to observe and analyze the sample surfaces. The AFM was able to detect the atomic structure and structural defects of the enamel crystal surface. The AFM and ESCA showed that structural defects in the enamel resulted from calcium deficiency. Adsorption of salivary protein to the enamel surface masked the atomic structure and calcium defects of the enamel crystal surface. Based on these results, AFM and ESCA techniques may be useful in determining the mechanisms of carious resistance and remineralization of dental enamel.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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