A conspicuous characteristic of Streptococcus mutans Rm-10 is that cell lyses occur immadiately after the logarithmic phase and two kinds of bacteriocins are liberated. However, frozen or lyophilized cells of Streptococcus mutans Rm-10 for a long period do not lyse after the logarithmic phase. This organism also show bactericidal activity against Enterococcus faecalis ODU as an indicator strain. Therefore, we attempted to isolate and purify a bacteriocin from Streptococcus mutans Rm-10 cells which have a stationary phase in the growth curve. The bactericidal substance was isolated from the supernatant fluid and concentrated by ammonium sulfate precipitation. We applied the crude active material to an Arginine Sepharose^[○!R] 4 B column. As a result, bactericidal principles were eluted from both non-adsorbed(N-ABC)and adsorbed fractions. Application of N-ABC to a Sephacry^<TM> S-100 column resulted in two peaks at the wavelength of 280 nm. The active fractions were found in the first peak. After 10 to 60% sucrose density gradient ultracentrifugation at 35, 000 rpm for 20h, N-ABC still remained at the top of the centrifuge bottle. N-ABC was also eluted through a Lysine Sepharose^<TM> 4 B column. The final N-ABC preparation was homogeneous as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis at a molecular weight of approximately 34 kDa. This band displayed antibacterial activity against the indicator strain. N-ABC was a carbohydrate-protein(1.67:1)complex, and was found to be rich in the sugars glucose, rhamnose, glucosamine, mannose and arabinose, and the amino acids alanine, lysine, glycine, glutamic acid, serine and threonine. These results indicate that the Streptococcus mutans Rm-10 used in this experiment produce a bacteriocin different from the two previously reported.

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We attempted to characterize a purified bacteriocin(N-ABC)elaborated by Streptococcus mutans Rm-10. Isoelectrofocusing revealed that the pl value of this purified material was 4.5. N-ABC was stable to heating at 100℃ for 30 min, but was partially destroyed by heat treatment at 121℃ for 10 min and 20 min. (Residual activities were 50% and 12.5%, respectively). Although N-ABC could withstand exposure to pH between 2.0 and 9.0, exposure to pH 11.0 resulted in complete loss of activity. It was partially destroyed with trypsin, pepsin, papain, α-chymotrypsin, β-galactosidase, α-galactosidase and endo-β-galactosidase, suggesting that the active site of this bacteriocin may exist both in protein and carbohydrate. It was active against other mutans streptococci as well as strains of Streptococcus salivarius, Enterococcus faecalis, Porphyromonas gingivalis and Fusobacterium nucleatum, but not against strains of Peptostreptococcus indolicus, Veillonella parvula, Prevotella melaninogenica, Prevotella intermedia or Prevotella nigrescens. N-ABC killed Enterococcus faecalis ODU immediately in a dosedependent manner by a bactericidal mode of action, because N-ABC did not display bacterial lysis on sensitive cells. The antibacterial effect of N-ABC was temperature dependent, with no killing at 4℃. These results indicate that this bacteriocin is similar to two bacteriocins previously reported by Muramatsu in mode of action, although it is different from them in isoelectric point, in its sensitivity to heat and enzymes, in its stable pH range and in its antibacterial spectrum.

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Using flow cytometry and immunohistochemical staining specimens, we examined the relationship between cellular immunity and the process of carcinogenesis. CD4 positive(CD4^+)and CD8 positive(CD8^+)cells increased in peripheral blood and tongue intraepithelial lymphocytes four weeks after administration of 4NQO in the rats. Compared with peripheral blood and tongue intraepithelial lymphocytes in the normal control group, CD4^+ cells increased in regions of hyperplasia and dysplasia, and CD8^+ cells increased significantly where there was dysplasia and carcinoma. Compared with normal cells, NKR-P1A positive and CD3 positive(NKT^+ like)cells were increased significantly in the peripheral blood and tongue intraepithelial lymphocytes when there was cancer. The expression of cellular immunity corresponded to histological changes during the development of carcinogenesis. These findings suggest that the development of 4NQO-induced carcinogenesis used in this study may mediate cellular immunity. We believe that changes in cellular immunity during carcinogenesis is accomplished by cell suppression factors such as the carcinogenesis factor.

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We evaluated the application of fluorides to the treatment of aging-related osteoporosis. Speculating that fluoride uptake by hard tissues depends on the concentration administered, we gave 2, 10, and 200 mg/L NaF solutions to senescence accelerated mice(SAM) from weaning until after 190 days, which is considered the developmental period for accelerated senescence, and evaluated its effect on bone metabolism. Dry bone weight and bone calcium concentration were greatest in the 10 mg group, while serum calcium level was the greatest in the 2 mg group. Calcium distribution in the bone was observed using an X-ray micro-analyzer. The distributed calcium concentration in the groups administered fluoride was greater than in the controls, being particularly high on the periosteal side compared with the middle area and the medial side of bone. These results suggest that the effects of fluoride administration on bone metabolism differ according to the concentration administered. Administration of 10 mg/L NaF solution may be effective in that results from aging delaying the decrease in the amount of bone.

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Using senescence accelerated mice(SAMR1 and SAMP8)of various ages, we determined normal ranges for 14 items of serum biochemistry and 12 hematologic values. The following seven items decreased with aging: RBC, Hb, Ht, ALP, iP, CRE, and albumin/globulin, while the following three items increased: RDW, TP and TG. Analysis of serum protein composition and amino acids indicated that SAMP8 mice have liver function lesions.

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We used computed tomography(GE Medical Systems)and Denta Scan to investigate bone healing after insertion of collagen sponge matrix(CSM) in tooth extraction sockets. One extraction site each in eight patients was evaluated. Each site had natural teeth mesial and distal to the site. CSM was placed to fill the extraction socket, and sutures were placed. Denta Scan was used to evaluate the healing at one day and three months. No complications, such as pain, bleeding, secondary infection or delay of epithelization, were observed. New bone formation or bone remodeling was observed clinically and radiographically where the CSM had been inserted. After three months the degree of comparative bone remodeling, as measured by the product of buccolingual length and socket depth, was between 60.1% and 94.3% respectively, with an average of 80.0%. We concluded that placement of CSM in the extraction socket between natural teeth was very effective not only for hemostasis, protection of the wound and promotion of healing, but also for new bone formation and prevention of alveolar ridge loss.

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Using lateral cephalometric radiographs of 8 deep-bite cases and 21 cases with normal occlusion, we investigated soft tissue changes during orthodontic treatment to find the relationship between the maxillary incisors and upper lip. Significant differences were found at three horizontal points(U1, Prn and UL)when soft and hard tissue points were measured horizontally and vertically in deep-bite cases and in those with normal occlusion. A high correlation was found between the position of the maxillary incisors and upper lip. Recurrent lines showing the relationship between these positional changes were calculated. The results of this study are useful in determining soft tissue position when planning orthodontic treatment.

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