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Notes: The recognition that destructive periodontal diseases may be caused by specific microorganisms in periodontal pockets has led to an increased interest in and usage of antimicrobial agents in periodontal therapy. Recently, a new controlledrelease insert containing ofloxacin, a synthetic antibiotic, has been developed. In this study, the controlled-release insert (PT-01) was microbiologically evaluated in combination with or without subgingival mechanical debridement. PT-01 was applied in the periodontal pockets of 27 patients with chronic periodontitis. Three sites with a deep probing pocket depth (≥5 mm) were randomly selected in different quadrants of each patient, and were assigned into three groups, i.e., PT01 applied (T), placebo applied (P) and control sites (C). Periodontal treatments consisted of supragingival scaling with oral hygiene instruction for the first 2 weeks followed by root planing and subgingival scaling. PT-01 was applied weekly on day 0 to 35, and the subgingival plaque samples from each site were collected on d 0, 14, 21 and 42. The dynamics of the subgingival microflora was investigated by dark field microscopy and by anaerobic and aerobic cultivation. In the supragingival scaling period, significant reduction in percentages of spirochetes and motile rods and significant increase of the percentage of coccoid cells were observed only at T sites. In addition, the total viable counts of bacteria, black-pigmented Bacteroides and Fusobacterium species were significantly reduced at T sites. After mechanical subgingival debridement, significant shifts in the proportion and reduction of the viable counts in the subgingival microflora were found at all sites. Although PT-01 applied sites showed some further shift in the proportion and reduction in subgingival microorganisms, statistically no significant differences in the microbiological results between the three groups of experimental sites were found. These results suggested that weekly application of PT-01 in the periodontal pocket could have significant effects on both qualitative and quantitative changes in the subgingival microflora. However, the mechanical subgingival debridement, consisting of root planing and subgingival scaling, was very effective in eliminating the subgingival microflora by itself. Then, in the combination with mechanical subgingival debridement, statistically no additional effects could be found. Consequently, it was suggested that the application of PT-01 might have an ameliorating effect as an adjunct in conventional periodontal therapy.

Notes: CD44 functions as a receptor for various extracellular matrices and plays crucial roles in homotypic and heterotypic cell-cell interactions. Recently, the molecular structure of CD44 has been extensively analyzed and multiple isoforms produced by alternative splicing of messenger RNA have been identified. In this study, we examined the expression of CD44 isoforms on different cell types isolated from periodontal tissue. In order to examine tissue differences in CD44 isoform expression, we established in vitro cell culture of human gingival fibroblasts (HGF), human periodontal ligament cells (HPDL) and human gingival epithelial cells (HGEC). These cells all expressed CD44 protein and messenger RNA. However, immunoprecipitation and Northern blot analysis revealed that HGEC expressed larger CD44 isoforms than HGF and HPDL. Reverse transcription-polymerase chain reaction with primers flanking the insertion site of alternatively spliced exons was used to study details of the heterogeneity. All cells examined expressed a major band in the absence of alternatively spliced exons and additional larger bands. In particular, HGEC contained more abundant high molecular mass species. In vitro stimulation by IL-1β, TNFα or phorbol 12-myristate 13-acetate induced an increase in total CD44 messenger RNA in HGF but not change in overall patterns of CD44 isoform expression. However, the isoform expression of HGEC was sensitive to cell density. The amount of larger isoform was decreased by culturing cells beyond confluence. These findings suggest that CD44 isoform expression is cell type-specifically regulated in periodontium and altered according to growth phase of HGEC.

Notes: Chronic adult periodontitis is usually characterized by inflammatory cell accumulation in the extravascular periodontal connective tissue. In order to reveal how the lymphocyte migration and retention in periodontal lesions is regulated, we have focused on the molecular basis for the adhesive interactions between lymphocytes and human gingival fibroblasts (HGF). In this study, we investigated the involvement of cell adhesion molecules in adhesive interactions between lymphocytes and HGF. We found that activated lymphocytes bound strongly to HGF and VLA integrins, extracellular matrix receptors, play crucial roles in the binding. Interestingly, we first revealed that CD44 molecules (hyaluronate receptor) on lymphocytes also participated in lymphocyte-HGF interactions and that hyaluronate anchored on the surface of HGF functioned as the ligand for CD44. In addition. when HGF were stimulated with inflammatory cytokines such as IL-1. TNFα and IFNγ, the binding avidity between lymphocytes and HGF was significantly increased and the adhesion was mainly mediated by LFA-l/ICAM-1 pathway. We then examined the possibility whether lymphocyte-HGF interaction may cause activation of HGF. When HGF directly interacted with lymphocytes for 3 h, IL-lβ mRNA expression was clearly increased in HGF. These findings suggested that the adhesive interactions between lymphocytes and HGF was mediated at least by VLA integrins, LFA-l/ICAM-1 and CD44/hyaluronate and that the heterotypic cell-cell interactions could mutually cause intracellular signal transduction.

Notes: Several growth factors (or cytokines) have been recently investigated for their use as potential therapeutics for periodontal tissue regeneration. The objective of this study was to evaluate periodontal tissue regeneration, including new bone and cementum formation, following topical application of recombinant basic fibroblast growth factor (bFGF, FGF-2) to furcation class II defects. Twelve furcation class II bone defects were surgically created in six beagle dogs, then recombinant bFGF (30 µg/site) + gelatinous carrier was topically applied to the bony defects. Six weeks after application, periodontal regeneration was analyzed. In all sites where bFGF was applied, periodontal ligament formation with new cementum deposits and new bone formation was observed histomorphometrically, in amounts greater than in the control sites. Basic FGF-applied sites exhibited significant regeneration as represented by the new bone formation rate (NBR) (83.6 ± 14.3%), new trabecular bone formation rate (NTBR) (44.1 ± 9.5%), and new cementum formation rate (NCR) (97.0 ± 7.5%). In contrast, in the carrier-only sites, the NBR, NTBR, and NCR were 35.4 ± 8.9%, 16.6 ± 6.2%, and 37.2 ± 15.1%, respectively. Moreover, no instances of epithelial down growth, ankylosis, or root resorption were observed in the bFGF-applied sites examined. The present results indicate that topical application of bFGF can enhance considerable periodontal regeneration in artificially created furcation class II bone defects of beagle dogs.