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Get PDFThe understanding of titanium by students in the dental faculty of Tokyo Medical and Dental University was surveyed from 1990 to 1996. A seven-item questionnaire was used in the survey conducted during the first lecture of the dental materials and science course. The students' basic understanding of titanium was not very good and did not improve with time. However, their understanding improved significantly after the lecture and laboratory instructions.departmental bulletin pape
Get PDFIn this graduate school of Tokyo Medical and Dental University, I was given a somewhat vague but farsighted theme by a professor： "protein-DNA interaction." Within these simple words, I was given a free hand. Being curious about the etiology of connective tissue diseases, I began to study the biochemistry and pathophysiology of autoimmunity, especially the nature of anti-DNA antibodies that are the principal anti-nuclear antibodies observed in patients with systemic lupus erythematosus (SLE). My thesis was on the characterization of serum anti-DNA antibodies purified by a novel method of affinity column chromatography.1 Thereafter, I remained involved in this fascinating field. In spite of the rapid progress in molecular immunology, the etiology of any particular systemic autoimmune disorder remains elusive at this point. Here, works on a monoclonal anti-DNA antibody performed in the laboratories of Dr. B. D. Stollar (Tufts University, Boston), Dr. Y. Kanai (University of Tokyo), and in our laboratory will be reviewed along with related articles.departmental bulletin pape
Get PDFWe investigated ectopic bone formation by biphasic calcium phosphate (BCP) combined with recombinant human bone morphogenetic protein-2 (rhBMP-2) in the rat dorsum. Under reduced pressure, rhBMP-2 was adsorbed onto BCP, which consisted of 80% β-tricalcium phosphate and 20% hydroxyapatite uniformly distributed in granules. Twenty Wistar rats were separated into 4 groups consisting of 5 animals each dosed with 2, 10, and 50 µg/700 µl of rhBMP-2 and a control group (BCP only). Pieces of the BCP-BMP complex or only BCP were implanted under the dorsal skin of the rats. Histological sections were examined three weeks later. New bone was formed in all rats given 50 µg doses, but not in the 2 µg and control groups. These results indicated that BCP combined with rhBMP-2 induced ectopic bone formation without additional carriers. Therefore, BCP granules alone can function as carriers for rhBMP-2 to induce bone formation.departmental bulletin pape
Get PDFSevere combined immunodeficiency (SCID) mice were immunologically reconstituted by the transfer of fetal liver cells (FLC) from BALB/c (SCID-isoFLC mice) or C57BL/6 mice (SCID-alloFLC mice). The developmental process of the immune system in the peripheral blood (PB) was almost comparable between SCID-isoFLC and SCID-isoFLC mice. Analysis of the lymphoid organs and the PB from SCID-alloFLC mice indicated that slg+ B cells appeared and were distributed to the periphery within 2 weeks after the transfer of FLC. It was also suggested that precursor T cells entered the thymus before 4 weeks after the transfer, and were differentiated into mature CD4+ or CD8+ T cells which then migrated to the periphery by 6 weeks. All of mature lymphocytes in the periphery of the SCID-alloFLC mice were shown to express donortype H-2 antigens. Additionally, in the SCID-isoFLC mice, cell-mediated immunity such as rejection against alloantigens was functioning from 6 weeks, and humoral immune function was suggested by the detection of cells generating antigen-specific antibodies. We discuss that development of the immune system in SCID mice receiving transferred FLC was comparable to that normally seen in the fetal and neonatal stages.departmental bulletin pape
Get PDFTo determine the significance of Epstein-Barr virus (EBV) in the tumorigenesis of Warthin tumor, formaldehyde-fixed and paraffin-embedded specimens of 21 tumors from 18 patients were examined by polymerase chain reaction (PCR)-Southern hybridization, in situ hybridization (ISH), and immunohistochemistry. PCR-Southern hybridization revealed the presence of EBV DNA in 13 of the 21 tumors (61.9%). However, ISH for EBV RNA showed that nuclei of the neoplastic epithelial cells of all tumors were negative. Although ISH for EBV DNA revealed that the nuclei of the neoplastic epithelial cells were positive in 4 of the 21 tumors (19.0%), the positive cells were sparsely distributed and there was no evidence of monoclonal proliferation of EBV positive neoplastic epithelial cells. Moreover, immunohistochemical reactions with antibodies against latent membrane protein 1 (LMP1) and EBV nuclear antigen 2 (EBNA2), were negative in all cases. Judging from these findings, we conclude that EBV does not play a major role in the tumorigenesis of Warthin tumor.departmental bulletin pape
Get PDFTo analyse the histological distribution of basement membranes (BM) in gastric adenocarcinomas, we produced a monoclonal antibody, BM909 (lgG 2b, kappa), which has been found useful for identifying the BM in routinely processed specimens. The BM 909 antibody was shown by ELISA to be negative against the three major BM components (type IV collagen, laminin and fibronectin). Gastric carcinomas from 78 patients including both differentiated and undifferentiated adenocarcinomas were classified into three types (tubular, trabecular, and isolated) based on the histological arrangement of the cancer cells. Histological distributions of the BM were also classified into four patterns (peritubular, peritrabecular, intratrabecular, and pericellular) based on the immunostaining results with the BM 909 antibody. Our results demonstrated a close relationship between these two parameters as follows: 1) the tubular type of gastric carcinomas showed a peritubular pattern of BM distribution in the differentiated adenocarcinomas; 2) The isolated type of gastric carcinomas showed a pericellular pattern of BM distribution in the undifferentiated adenocarcinomas; and 3) The trabecular type of gastric carcinomas showed either peritrabecular or intratrabecular patterns of BM distribution, in both differentiated and undifferentiated adenocarcinomas. In conclusion, we suggest that all gastric adenocarcinomas are accompanied by BM deposition regardless of the degree of histological differentiation.departmental bulletin pape
Get PDFMany researchers have demonstrated that the administration of prostaglandins (PGs), especially PGE2, increases the bone volume in vivo. It is still not clear how endogenous PG is associated with such bone formation. Cyclooxygenase (COX), which acts in the synthesis of PG from arachidonic acid, has been recently revealed to have two subtypes, a constitutive type (COX-1) and an inducible one (COX-2). We examined the expression of each COX subtype during osteogenesis with the established model of the rat tibial medullary cavity in which osteogenesis can be induced by the injection of colchicine. The expression of both COX-1 and COX-2 genes was enhanced after colchicine injection in the early stage before the start of bone formation. Only the COX-2 gene expression was elevated again later during the beginning of bone formation. Furthermore, the daily administration of indomethacin, COX inhibitor, could reduce the bone mass induced by colchicine in the rat tibiae. These data indicate that endogenous PGs are associated with osteogenesis in this model. Moreover, the present study suggests that COX-2 and COX-1 would both be involved in the early stage of osteogenesis, and COX-2 is likely to be more associated with the maturation of osteoblasts in the later stage.departmental bulletin pape
Get PDFIt is difficult for both prosthodontists and their patients with large marginal defects to achieve a satisfactory prosthodontic result, because retention, support, and stability of the prosthesis are limited and recovery of esthetics is unsatisfactory owing to large mandibular defects. Alveolar ridge augmentation therapy is performed to compensate for such problems. We have experienced a good prognosis of prosthodontic treatment for over 10 years in two patients with large marginal defects of the partially edentulous mandible, who had undergone grafting of porous hydroxyapatite blocks to their bone defects. It has been reported that porous hydroxyapatite blocks are unsuitable for edentulous patients, because the mucosa covering the hydroxyapatite block is too thin and delicate to support dentures. We, therefore, designed the denture to prevent concentration of occlusal stress on the mucosa. In both of these two cases, we achieved recovery of occlusal function and esthetics by affixing denture to the large marginally resected defect augmented with a graft of porous hydroxyapatite block.departmental bulletin pape
Get PDFThe aim of this study is to clarify the normal relationship between jaw elevator muscle activity and occlusal contact in lateral positions in order to assess the appropriate anterior guidance of lateral jaw movements for occlusal reconstruction and treatment. The EMG-activity of the right and left masseter, anterior temporal, and posterior temporal muscles of 9 healthy subjects with full, natural dentition was measured with bipolar surface electrodes during two different biting efforts, one involves bite registration by a silicone material containing carbonate powder (BRS) and another is maximal voluntary clenching (MVC), at the right and left canines' edge to edge positions and intercuspal position. The difference in muscle activity between MVC and BRS, which was regarded as the actual muscle activity necessary for MVC, was calculated as a representative value for each muscle activity. When working-side occlusal contact was restricted by the anterior teeth, including the canines, the total actual EMG activity of the 6 jaw muscles had a significantly strong correlation with the frontal angle of the lateral incisal path and the occlusal contact area at the lateral occlusion. This result suggested the possibility that canine guidance would control the muscle activity during lateral tooth clenching.departmental bulletin pape