Shikaigaku

Human gingival fluid, nonstimulated whole saliva, and serum were collected from healthy individuals and those with periodontal disease. Gingival fluid and whole saliva were centrifuged to remove cells and debris, and then sterilized with a 0.45μm Millipore filter.
Secretory IgA (sIgA) was found in the saliva of both healthy individuals and those with periodontal disease by enzyme immunoassay specific to sIgA, although gingival fluid sIgA was not detected. sIgA levels in the serum were 1/30 that in saliva. However, no correlation was found for the relationship between sIgA levels in the serum and those in the saliva.
We also investigated whether human gingival fluid and saliva had biological activity enhancing DNA synthesis of C57BL/6N and BALB/cA mouse splenic lymphocytes in vitro. The ability of lymphocytes to undergo DNA synthesis in response to stimulus by gingival fluid, saliva and serum was assessed by measuring the incorporation of ^3H-TdR.
It was found that gingival fluid affected DNA synthesis of lymphocytes although it had little effect on saliva and serum. Stimulation of lymphocyte proliferation by gingival fluid from individuals with periodontal disease was high compared with healthy individuals. The lymphocyte response induced by gingival fluid was higher in cells from BALB/cA than in C57BL/6N mice.
From the above, it was concluded that a biologically active substance in the human gingival fluid and sIgA in the saliva both play different roles in host defense.

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Previous studies have shown the presence of various types of appendages on the surface of Bacteroides intermedius strains. Strain 17 possesses type C fimbriae which agglutinate strongly with 5 different species of erythrocytes and adhere strongly to human buccal epithelial cells.
In order to clarify the fimbrial hemagglutination of Bacteroides intermedius, fimbriae from B. intermedius strain 17 were purified by means of mechanical shearing, 50% ammonium sulfate precipitation, solubilization by deoxycholate, ultracentrifugation in a 10〜60% linear sucrose gradient, and elution by DEAE-Sepharose CL-6B. A fimbriae fraction band which exhibited hemagglutination activity was obtained at a density of 1.10〜1.15g/ml. Fimbriae at a second peak were eluted from a DEAE-Sepharose CL-6B column using a salt gradient of increasing concentration. This hemagglutination active fraction was immunologically and morphologically homogeneous.
These results suggest that hemagglutination activity may be associated with fimbriae.

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Identification, proportional distribution and antimicrobial susceptibility were examined of Bacteroides forsythus isolated from periodontal pockets, an alveolar abscess and a dentigerous cyst. Non-black pigmented, fastidious Bacteroides with trypsin activity were chosen for this experiment. Clinical isolates were identified by means of an API ZYM system. The DNA-DNA dot hybridization technique was utilized as an additional identification tool. B. forsythus ATCC43037 was labelled by photobiotin for DNA-DNA hybridization.
All strains showed enzymatic activity patterns similar to ATCC type strain. Morphological and SDS-PAGE studies revealed one strain derived from an alveolar abscess case was different from the others. However, DNA of this strain was homologous to the labelled DNA of the B. forsythus type strain. Therefore, all strains tested were identified as B. forsythus. B. forsythus was isolated from 40% of the periodontal pockets of patients with advancing periodontitis. In most cases, the proportional distribution of B. forsythus were approximately 2%, although it was greater than 10% in two cases. Organisms from periapical lesions were more resistant to antibiotics than those from periodontal pockets. Clindamycin was effective against all the bacterial strains tested. Periodontal pocket bacteria were sensitive to metronidazole.
In conclusion, the API ZYM system is useful for identification of B. forsythus. When B. forsythus represents greater than 10% of the organisms in periodontitis, it may exert an important influence on exacerbation due to its ability to produce trypsin.

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It is important to predict caries incidence in order to effectively prevent dental caries in the permanent teeth of elementary school children. Nakai found that the deft and DMFT scores in first graders were valid factors in predicting caries incidence. The purpose of this study was to examine whether these score were useful in predicting caries in permanent teeth of elementary school children who had low caries incidence.
The subjects were 386 children who entered elementary school in 1980, 1981 and 1982. Dental examinations were carried out for 8 years, and topical fluoride applications were given twice a year using an APF gel. Three factors were examined for predicting caries incidence : the deft score, number of erupted permanent teeth (NP) and the caries experience of the permanent teeth in the first grade. Subjects were divided into three groups having deft scores of less than 5, between 5 and 13, and greater than 13 in the first grade. Dental caries experience in the permanent teeth was lower during the examination period in the first group than in the others. Subjects were also divided into three groups having NP less than 3, between 3 and 6, and greater than 6 in the first grade. There was no difference in the caries incidence among these groups as a function of tooth age. The subjects were also divided into two groups, based on whether or not their DMFT score was 0. Children with caries experience in the permanent teeth in the first grade had significantly greater caries incidence in the sixth grade than those with 0 DMFT scores.
It is suggested that the deft and DMFT scores in the first grade are valid factors in predicting caries incidence. It was also found that these factors could be used to predict caries incidence in children in whom topical fluoride applications had been carried out. The deft score in the first grade was particularly effective for predicting caries incidence in low caries incidence children during the experimental period.

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