Preliminary evaluation of the performance of dual energy x-ray absorptiometry (DEXA) demonstrated a number of benefits for application to the mandible: excellent accuracy, good replication, little effect on absootion by soft tissues and little influence of the distance between the bone and the scanning table. DEXA measurement of the bone mineral density (BMD) was undertaken in 211 normal volunteers (104 males and 107 females) and 48 hemodialysis patients (29 males and 19 females). The mandible, lumbar spine, femoral neck, greater trochanter and radius were the sites of measurements. In the normal volunteers, the patterns of BMD changes at five sites differed by age and sex. The BMD changes in the mandible differed by sex. BMD decreased almost consisitently during menopause in females. In males, BMD decreased slightly after 50 years of age. The BMD decrease by aging was the least in the mandible in both sexes, compared to the four other sites. This indicates the specific characteristic of the mandible. In the hemodialysis patients, BMD at the five sites showed different patterns of change in relation to age, sex and duration of hemodialysis and different patterns of BMD changes were demonstrated between the hemodialysis patients and the normal volunteers. At all the five sistes examined, the duration of hemodialysis seemed to have a stronger effect on BMD than aging. BMD measured at the five sites, BMD in the mandible was most closely correlated to the duration of hemodialysis.

Subsets of T lymphocytes in specific and non-specific immunity were studied to investigate their participation as antitumor effector. In ⁵¹Cr-release assay the spleen cells from mice treated with OK-432 had 32.4% cytotoxicity and those with BCG 31.7% cytotoxicity by spontaneous tumor at an E/T ratio of 40:1. In specific immunization, the cytotoxicity of non-treated spleen cells was 53.5%. The cytotoxicity was higher in specific immunization than non-specific immunization. When the spleen cells were treated with anti-Thyl.1 + rabbit complement (C), anti-Lyt1.2 + C, anti-Lyt 2.2 + C or anti-L3T4 + C, the cytotoxicity was more effectively inhibited in specific immunization than non-specific immunization. These results suggested that T cells constituted the majority of antitumor effector in specific immunization and the ratio of T cells as antitumor effector was lower in non-specific immunization. Furthermore, in mice injected OK-432, the ratio of T cells as antitumor cells was lower than in mice injected BCG.

We studied the properties and biological activities of δ-toxin purified from Staphylococcus epidermidis. The hemolytic activity of purified δ-toxin against human erythrocytes is thirty-one fold higher than that of culture supernatant. By the analysis of SDS-polyacrylamide gel electrophoresis, the molecular weight of δ-toxin is about 3,000, and by isoelectric foucusing, two fragments were observed at the position of pH 5.1 and pH 9.0. Human erythrocyte is most sensitive to purified δ-toxin, and horse, rabbit, mouse, and sheep one follow in the order. The hemolytic activity was inhibited by phoshathidylcholine, and also inactivated by proteolytic enzymes such as trypsin,α-chymotrypsin and papain. β-D-Glucronidase was released from neutrophils dose-dependently by δ-toxin. The lymphocyte blast transformation was also observed by treatment with δ-toxin at the dose of 0.02 and 0.2 hemolytic unit.

The δ-toxin of S. epidermidis is similar to the δ-toxin of S. aureus in properties and biological activities. These suggest that it may be one of the pathogenic factors in S. epidermidis infection.

We studied the occurrence of Capnocytophaga spp. and Haemophilus actinomycetemcomitans in periodontal pockets using selective medium. The subjects examined in this study consisted of 148 students (75 junior high school students and 73 high school students) . They were divided into four groups by clinical examination: simple gingivitis (SG) group, proliferative gingivitis (PG) group, adult periodontitis (AP) and juvenile periodontitis (JP) group and control group. Capnocytophaga ochracea could be isolated almost equally from both healthy and affected sites. However, the occurrence of Haemophilus actinomycetemcomitans varied significantly among the groups by Chi-square test. In the PG group and AP and JP group, no statistically significant age-and sex-differences were found in the microbe-positive rates.

It was concluded that Haemophilus actinomycetemcomitans occurred frequently at periodontal diseased sites in junior high school students and high school students.

To assess the propriety of surgical correction of lingual frenulum, the morphology of lingual frenulum and the position of its attachment to the tongue were studied in 3-to 6-year-old children (146 with normal frenulum and 20 with frenulum contraction) seen at the Department of Pediatric Dentistry, School of Dentistry, Iwate Medical University. In the latter group of children, changes in the morphology and the position of attachment to the tongue with time were closely investigated. Of the children with normal frenulum, the morphology could be categorized as a membranous type in 74.7%, cordal type in 11.6% and intermediate type in 13.7%. The frenulum had non-root at its origin in 21.9%, a single root in 13.7%, double roots in 31.5% and triple roots in 32.9%. Thus, the fan-shaped type of origin was frequent. The distance between the top end of the marginal gingiva and the origin of the frenulum was approximately 4㎜ in any age groups. The distance between the lingual apex and the attachment showed no significant differences by ages but tended to increase with age. The distance between the sublingual caruncle and the attachment of the frenulum increased significantly from 3 years to 6 years of age.

The distance between the sublingual caruncle and the lingual apex also tended to increase with age, and especially significant differences were demonstrated between the age of 3 years and the ages of 4, 5 and 6 years. Long-term follow-up in the children with frenulum contraction showed that in 70% of them, the position of the attachment of the frenulum to the tongue became closer with the lapse of time to that found in the children with normal frenulum. In 78.6% of them, the follow-up period extended for more than 2 years. This seemed to indicate that frenotomy in young children should wait until after at least 2 years of observation, unless immediately indicated for any existing disorder.