Biomedical subjects

Naoya Izumi

Publications and source records attributed to Naoya Izumi.

3 recordsLinked to original sources

PubMed2005

The use of enamel matrix derivative (Emdogain) for improvement of probing attachment level of the autotransplanted teeth.

The enamel matrix derivative (EMD, Emdogain) was used for the purpose to obtain the periodontal regeneration on the denuded root-surfaces of the donor teeth in two cases of the immediate tooth-transplantation. The root-surfaces at the cervical portion of the teeth were denuded because of extrusion. The healthy periodontium of each tooth remained at the apical portion of the roots. The denuded root-surfaces were cleansed before extraction. Then, the donor teeth were gently extracted with forceps, administered EMD, and transplanted so that the denuded surfaces were covered by gingival flaps. After the transplantation, the mean probing attachment level (PAL) improved 3.2 mm and 1.5 mm, respectively. The mean probing pocket depth was within normal level. The actual supporting areas of the roots of the transplanted teeth increased and the teeth worked as the abutments of prosthetic bridges.

Biocompatible Materials↗

PubMed2003

Osteoclast differentiation in ectopic bone formation induced by recombinant human bone morphogenetic protein 2 (rhBMP-2).

Osteoclast differentiation in the process of ectopic bone formation induced by recombinant human bone morphogenetic protein 2 (rhBMP-2) was examined to clarify the relationship between osteoclast development and rhBMP-2-induced bone formation. A combination of rhBMP-2 with a porous microsphere (PMS) and blood clot was implanted subcutaneously on the bilateral chest muscles of rats. Tartrate-resistant acid phosphatase (TRAPase) activity, cathepsin K (cath K), and calcitonin receptor (CTR), as markers of osteoclasts and their precursors, were examined using enzyme and immunohistochemical analysis up to 7 days after implantation. Mononuclear cells positive for TRAPase, cath K, and CTR first appeared on day 3 in connective tissue surrounding the PMS after implantation of rhBMP-2. Simultaneously, alkaline phosphatase activity became detectable in mesenchymal cells in the connective tissue. Electron microscopy demonstrated some mononuclear cells with abundant mitochondria and poorly developed rough endoplasmic reticulum in the proximity of mesenchymal cells. However, there was no evidence of cartilage or bone matrix formation on day 3. Osteoclasts in various stages of development, classified by the pattern of immunoreactivity for cath K, were observed by day 7. The polarized intracellular distribution of cath K was found only in osteoclasts attached to bone matrix. In conclusion, we have demonstrated for the first time the appearance of osteoclast precursors before bone matrix formation induced by rhBMP-2, suggesting that bone matrix is not a prerequisite for osteoclast precursor recruitment. Furthermore, we suggest that differentiation into polarized functional osteoclasts is accomplished when the osteoclasts attach to the bone matrix.

Animals↗

PubMed2003

Jaw bone remodeling at the invasion front of gingival squamous cell carcinomas.

BACKGROUND: It is still unknown how jaw bone remodeling occurs at actual invasion sites of oral squamous cell carcinomas. Since there is no other human carcinomas which make a direct invasion of the bone, gingival carcinomas are valuable examples. METHODS: Twelve surgical specimens of gingival squamous cell carcinoma were examined histopathologically and immunohistochemically for remodeling of bone and its surrounding tissue. RESULTS: Three types of bone interfaces with carcinomatous invasion were distinguished. These included areas with bone resorption, smooth bone surface and new bone formation. In the bone-resorption area, numerous osteoclasts were located along the bone surface, which was surrounded by myxoid stroma. The myxoid stroma was characterized by immunopositivity for heparan sulfate proteoglycan (HSPG), abundant vascularity and macrophagic infiltration. In the bone-formation area, rows of osteoblasts were aligned on the bone surface. The stroma around osteoblasts was also HSPG-immunopositive, poor in vascularity but rich in activated fibroblasts. In the smooth-bone area, the stroma showed an organizing phase of granulation tissue with slender fibroblasts and mature collagen fibers but with less vascularity and inflammatory infiltrates. CONCLUSION: The results indicate that the stromal architecture, especially in terms of its inflammatory cellular, vascular and matrix compositions, is strictly regulated in the timing and site of jaw bone remodeling which is causes by carcinomatous invasion.

Antigens, CD↗