Yoshifumi Iwamoto

Correlation Between the Protease Activities and the Number of Epithelial Cells in Human Saliva

The positive significant correlation (r = 0.788, n = 37) was shown between the protease activity and the number of epithelial cells (not of leukocytes) in saliva. There was little protease activity observed in glandular saliva. It is possible to conclude from the results that a main source of salivary protease is the epithelial cells in saliva. It was also found that the oral prophylaxis reduced the numbers of epithelial cells and leukocytes and the protease activity.

The effects of oestrogen on osteocalcin production by human periodontal ligament cells

The purpose was to investigate the effects of oestradiol on the function of periodontal ligament (PDL) cells by measuring the production of osteocalcin in vitro. Cells were obtained from the healthy periodontal ligament of teeth extracted from two males and two females for orthodontic reasons. Serum-free medium was used when testing the effects of oestradiol on PDL cells. The amount of osteocalcin in the culture medium was analysed by two-step sandwich enzyme immunoassay in the presence or absence of oestradiol. It was shown that oestradiol enhanced the production of osteocalcin by PDL cells in a time- and dose-dependent manner. PDL cells obtained from both male and female donors were affected by oestradiol. It thus appears that oestradiol is one of the factors important for PDL cells to express their function.

Expression of Syndecan-2, -4, and Fibroblast Growth Factor Receptor Type 1 in Human Periodontal Ligament Fibroblasts and Down-regulation of These Membrane Proteins during Maturation in Culture

Syndecans are transmembrane heparan sulfate proteoglycans. They are known to interact with basic fibroblast growth factor (bFGF), and it has been suggested that they play important roles in the growth, morphology, and migration of a variety of cell types. We examined the expression of syndecans and fibroblast growth factor receptor type 1 (FGFR1) in periodontal ligament (PDL) cells, because these membrane proteins may play roles in the control of growth and differentiation during regeneration of PDL. Reverse-transcription/polymerase chain-reaction (RT-PCR) showed that PDL cells expressed syndecan-2 and -4 mRNAs. This was confirmed by sequence analysis of the PCR products. When PDL cells were maintained for 25 days, alkaline phosphatase (ALPase) activity gradually increased and reached a maximal level on day 20. Northern blotting analysis showed that PDL cells expressed 2.3-kb syndecan-2, 2.6-kb syndecan-4, and 2.8-kb FGFR1 mRNAs throughout the entire culture period, whereas no syndecan-1 mRNA was detectable by this method. Maximal levels of syndecan-2, -4, and FGFR1 mRNAs were observed on day 5. However, their levels were markedly decreased on days 20 and 25. Accordingly, the inhibitory effect of bFGF on ALPase activity was less on day 20 than on day 5. When PDL cells were pre-treated with heparitinase, a mitogenic response of PDL cells to bFGF was decreased. These observations indicate that PDL cells express syndecan-2, -4, and FGFR1 mRNAs, and that those levels are changed with the increase in ALPase activity in culture. The reductions in syndecan-2, -4, and FGFR1 levels may be involved in the control of growth and differentiation of PDL cells during development and regeneration.

ANALYSIS OF OESTROGEN RECEPTOR MRNA BY REVERSE TRANSCRIPTASE-POLYMERASE CHAIN REACTION IN HUMAN PERIODONTAL LIGAMENT CELLS

Periodontal ligament (PDL) cells have osteoblast-like features and are capable of differentiating into osteogenic cells. As human osteoblasts express oestrogen receptor mRNA, it is possible that PDL cells do so also, but findings have been conflicting. To determine whether they do express oestrogen receptor mRNA, the reverse transcriptase-polymerase chain reaction was performed with two different primers. Cells were obtained from a healthy periodontal ligament of premolar extracted for orthodontic reasons. The human breast adenocarcinoma cell-line MCF7 was used as a positive control. Expression of oestrogen receptor mRNA was detected in PDL cells with one of the primers but with less intensity than in MCF7 cells. Southern hybridization confirmed these results. These findings suggest that PDL cells express oestrogen receptor mRNA at low levels.

Heterogeneity of Peroxidase Related to Antibacterial Activity in Human Parotid Saliva

The peroxidase that is related to the thiocyanate-peroxidase-hydrogen peroxide antibacterial system in human parotid saliva was separated into three subfractions by diethylaminoethanol (DEAE)-cellulose column chromatography. Heterogeneity was confirmed by isoelectric focusing. Three subfractions contributed to the inhibition of the growth of Lactobacillus casei ATCC 7469.

Correlations Between Salivary Protease and Supragingival or Subgingival Calculus Index

Significant positive correlations between protease activities in saliva and supragingival/subgingival calculus indices, periodontal pocket depth, or P-M-A index were confirmed. When the partial correlation was calculated, the subgingival calculus index correlated well with the sediment protease at pH 8.5, and the supragingival calculus index showed a significant correlation with the supernate protease at pH 4.5.

An Analytical Study on Gender Differences in Self-Reported Oral Health Care and Problems of Japanese Employees

An Analytical Study on Gender Differences in Self‐Reported Oral Health Care and Problems of Japanese Employees: Makoto Kawamura, et al. Department of Preventive Dentistry, Hiroshima University School of Dentistry—The purpose of this survey was to clarify gender differences in self‐reported oral health care and problems of Japanese employees. A 60‐item questionnaire named Dental Checker® was used in a project on oral health in the working place. Subjects were 77,845 Japanese employees (males, 52,345; females, 25,500). The Mantel‐Haenszel chi‐square test was used to clarify gender differences among respondents. Of great significance was a finding that 81.8% of females felt uncomfortable when they slept without brushing their teeth, as contrast with 58.8% of males (P<0.001, OR=3.22). Nearly one half of male employees answered that they were too busy to go to the dentist, while 36.8% of females answered in this way (P<0.001, OR=1.83). Only a minority reported occasional use of dental floss (males; 13.2%, females; 24.9%, P<0.001, OR=2.04). Significant gender differences were found for all 18 behavioral items, and in each case, females generally reported ‘healthier’ behavior than males. Although differences between genders were small with respect to their assessment of the risk factors of periodontal disease, male employees were more likely to report bad breath, enlarged spaces between teeth, food impaction, chewing restriction, and tooth mobility than females (P<0.001, OR=1.26‐1.78). Findings suggest that gender as well as age remains an important consideration when planning dental health education or other interventions at the workplace.

Effects of fluoride intake on the mineral content, acid solubility and resorption caused by experimental periodontitis of rat alveolar bone

Adult rats were given either distilled water or drinking water containing 100 parts/10(6) of fluoride. The alveolar bone of rats given fluoride for 90 days showed an increased mineral content and decreased acid solubility compared to the bone of rats given distilled water. Experimental periodontitis was initiated in both groups after 110 days of treatment to cause alveolar bone resorption. Fourteen days later, the rats were killed and it was found that the alveolar bone resorption caused by experimental periodontitis was significantly smaller in the rats given fluoride in their drinking water than in those given distilled water. The findings suggest that fluoride intake might have a protective effect on rapidly progressing alveolar bone resorption.

Lysis of Streptococci by Lysozyme from Human Parotid Saliva and Sodium Lauryl Sulfate

Egg-white lysozyme (EC 3.2.1.17) has little effect on bacteria (including Streptococcus mitis and Streptococcus salivarius) indigeneous to the oral cavity of man (R. J. GIBBONS, J. D. STOPPELAAR, and L. HARDEN, J Dent Res 45:877, 1966). Recently, it has been shown that relatively lysozyme-resistant Streptococcus faecalis can be lysed by brief incubation with lysozyme, followed by the addition of sodium lauryl sulfate (SLS) or sodium chloride (R. H. METCALF and R. H. DEIBEL, J Bact 99:674, 1969). In our previous work (Y. IWAMOTO ET AL, J Dent Res 49:1104, 1970), lysozyme from human parotid saliva was purified successfully. It had a specific activity three and a half times greater than that of hen egg-white lysozyme and a composition that was different, especially in regard to tyrosine, serine, and glutamic acid contents. There have been no reports on the lysis of streptococci by parotid lysozyme. The purpose of this study was to observe the lysis of streptococci through the synergistic effect of SLS and lysozyme from human parotid saliva. Streptococci used in this study were S salivarius ATCC 9222, S mitis ATCC 9811, Streptococcus sanguis ATCC 10556, S sanguis ATCC 10557, and Streptococcus mutans strains GS-5, HS-6,* AHT, and FA-1.t Cells were inoculated from the thioglycolate agar stabs into a modified medium (K. S. BERMAN, R. J. GIBBONS, and J. NALBANDIAN, Arch Oral Biol 12:1133, 1967). After incubation for several hours at 37 C, cells in the exponential phase cultures were centrifuged and washed twice in cold distilled water. They were suspended in aliquots of 1/15 M Tris-HC1 buffer, pH 9.0. Lysis experiments were carried out according to the methods of Metcalf and Deibel (J Bact 99:674, 1969). Cells were resuspended in 4 ml lysing medium; the mixture contained TrisHC1 buffer (pH 9.0) in a final concentration of 1/15 M and 60 [tg of the purified parotid lysozyme. The reaction mixture was incubated at 37 C in a water bath with shaking. After ten minutes incubation, 0.1 ml of 0.32 M SLS was

The concentration of salivary steroid hormones and the prevalence of gingivitis at puberty.

Gingival conditions of 1323 junior high schoolchildren aged 12-15 were examined, and 132 children who had either healthy gingivae or severe gingivitis were called to the clinic. More precise examination of gingivitis was performed by assessment of Jacksons gingivitis index (G.I.), probing depth (P.D.), and bleeding on probing. Whole saliva was collected, and the salivary concentrations of estradiol, progesterone, and testosterone were determined by radioimmunoassay. Subgingival bacterial plaque was sampled from 36 children, and total bacterial counts and morphological differentiation were performed under a phase-contrast microscope. For statistical analysis, both males and females were divided into two groups according to the concentration of each sex hormone and subgrouped by the results of clinical examinations. Chi-square analysis using 2-by-2 tables was performed to determine the relation between salivary steroid hormone levels and gingival inflammation. The results suggest that unbalanced secretion of certain hormones might be one of the factors promoting gingivitis at puberty.