Kaizo Shimura

Study on the efficacy of biodegradable poly (L-lactide) mesh for supporting transplanted particulate cancellous bone and marrow : Experiment involving subcutaneous implantation in dogs

Poly(L-lactide) (PLLA) mesh sheets, monofilaments and mesh cylinders filled with fresh autogenic particulate cancellous bone and marrow (PCBM) were implanted subcutaneously into the back of 22 adult dogs for 1 yr. Polypropylene (PP) was used as a control. The inflammatory response to PLLA mesh sheets was slight, similar to PP mesh sheets. However, 3 months after implantation, histiocytes and multinucleate giant cells appeared on the surface of the monofilaments of PLLA mesh sheets and gradually increased in number as the monofilaments were degraded and absorbed. Almost no inflammatory cellular infiltration was seen in the tissue around PLLA mesh sheets or between the monofilaments. When a PLLA mesh cylinder filled with PCBM was implanted subcutaneously, the bone formation reached its peak 1 month after implantation, as in the case of a similar PP mesh cylinder, and bone formation was observed along the inner wall of the cylinder. In addition, a vascular net was abundant within the cylinder. The mechanical strength of the test material (PLLA monofilaments) did not change for almost 2 months after implantation, and 80% of its initial strength was retained for 3 months. These observations suggest that a PCBM graft supported by PLLA mesh would be very effective in the reconstruction of damaged maxillofacial bones, since histological tissue reactions associated with biodegradation of the PLLA mesh are mild and the PLLA mesh does not interfere with bone formation of PCBM. It was also found that the PLLA mesh retains its mechanical strength long enough to allow the PCBM transplant to develop sufficient strength to sustain the damaged region.

Reduction in tumour formation on porous polyethylene by collagen immobilization

After surface modification with collagen immobilization through covalent bonding, porous polyethylene pieces with an average pore size of 400 microns were implanted subcutaneously into the back of rats for 1 yr. It was found that connective tissues with abundant blood vessels were formed clearly, filling more than 90% of the pore volume and bound firmly to the pore walls. A tumour was found in only one of 24 implanted pieces (4.2%). On the other hand, the virgin porous polyethylene pieces without collagen immobilization exhibited inflammatory reactions within the pores and the connective tissues produced filled only 15% of the pore volume. Formation of a malignant histiocytoma was observed in 11 of the 24 pieces which had been implanted (45.8%). Thus, immobilization of collagen on the surface of an artificial material through covalent bonding proved to be very effective not only for firm bonding with soft connective tissues but also for a reduction of tumour formation.

Gastrointestinal mucosal cyst of the oral cavity: report of case and review of literature.

The presence of a gastrointestinal cyst or heterotopic mucosa in the oral cavity is a very rare condition. Gorlin and Jirasek reviewed the literature in 1970 and reported 12 cases of cysts containing gastrointestinal mucosa, including one of their own, and two cases of masses of heterotopic gastrointestinal tissue in the oral cavity.’ Following their report, 15 additional cases of gastrointestinal cyst2-12 and three cases of masses of heterotopic gastrointestinal tissues”-” in the oral cavity have been described. This report describes an additional case of this rare condition.

Clinical evaluation of 67Ga-citrate scanning in the oral region.

Gallium-67-citrate was administered to thirty-nine patients who had a variety of benign, malignant, and inflammatory lesions of the oral region. The gallium-67 scintigram was noted to be valuable in the diagnosis of maxillary carcinoma, parotid carcinoma, and malignant lymphoma. Clinically, it is possible to differentiate malignant tumors from benign ones with the aid of 67Ga scanning. It is difficult, however, to differentiate malignant tumors from inflammatory lesions. At present, it is difficult to defect the small malignant lesion by means of a 67Ga scintigram.

Cell kinetic analysis of oral squamous cell carcinoma by using nuclear DNA-RNA contents and antibody to bromodeoxyuridine.

Concerning cell kinetics of oral cancer, the following findings were obtained as a result of both measurement of nuclear DNA-RNA contents, and examination using antiBromodeoxyuridine (BrdU) monoclonal antibody.1. A significant difference was noted between the BrdU labelling index of normal gingival epithelium (2.9±0.5%) and that of oral squamous cell carcinoma (11.4±3.8%) . In the normal epithelium positive identification was restricted to the basal cell layer or the 2nd-3rd supra basal cell layers ; while in squamous cell carcinoma, it was commonly observed to occur around the focus of tumor cells in the well differentiated area, and was seen scattered in the poorly differentiated area.2. No definite relationship was observed between the BrdU labelling index and clinical stages of tumor. With respect to the relationship with histopathological malignancy, the labelling index did not show any association with the grading of differentiation or atypia, but showed positive correlation with the mitotic index. The value of the labelling index was 11.5 times as large as that of mitotic index.3. With the introduction of the BrdU labelling index applied to the results of measurement of nuclear DNA-RNA contents was it admittedly possible to clarify its significance in oral squamous cell carcinoma, a factor which had not been revealed by conventional analyses.