The composite of apatite from calcium-asparatic acid (Asp) complex and gelatin was prepared and evaluated the bone response after the implantation into the cortical bone of rabbit tibiae. Four kinds of porous materials were employed in the present study. Namely, Gelatin: 3 wt % gelatin gel, Gelatin-Arg: 3 wt % gelatin-arginine (Arg) gel, CAP-Gelatin: L-Asparatic acid-Ca(OH)2-H3PO4 and 3 wt % gelatin gel, CAP-Gelatin-Arg: L-Asparatic acid-Ca(OH)2-H3PO4 and 3 wt % gelatin gel-Arg. These samples were freeze-dried and were sterilized with ethylene-oxide gas. Afterwards, four porous materials were implanted into the cortical bone defects of rabbit tibiae. After the 12 weeks of implantation, bone responses were evaluated by the observation of non-decalcified thin sections.The histological appearances of Gelatin implantation promoted the limited bone formation and the space of bone defects was still present. Degradation residue of gelatin was observed close to the new bone. For Gelatin-Arg implantaion, greater degree of bone formation was observed compared with Gelatin implantation. CAP-Gelatin and CAP-Gelatin-Arg implantation showed the partial new bone formation in the bone defects. Greater amount of degradation residue was observed in the space of bone defects rather than Gelatin and Gelatin-Arg implantation. Apatite particle and degraded gelatin could be observed inside the space of bone defects. It is suggested that degraded gelatin influenced the bone formation.
An in vitro embryonic stem cell test allows the screening of potential reproductive and developmental toxicities, but does not reflect human metabolic activators. Thus, a novel test for the hybrid cultures of hepatocytes and mouse ES cells should be developed. To develop procedures for the hybrid cultures of three kinds of hepatocyte and mouse ES cells, basic structures for hybrid cultures and two scaffolds for three-dimensional cultures were examined to determine optimal experimental conditions.In the comparison of basic structures for hybrid cultures, the incidence was slightly higher with hepatocytes placed outside the inter cell and embryo bodies (EBs) inside. As a result of the comparison of the scaffolds, glass fiber showed a slightly higher incidence than collagen gel scaffolds.
The embryotoxicity risk of indium-containing dental alloys was examined. Ag-20% In and Ag-Pd-Au-Cu In (6% In) alloys were experimentally prepared, and their embryotoxicity risk was examined by the Embryo Stem Cell Test (EST) protocol. Abutment teeth were prepared for the left and right molar regions in an upper and lower jaw model to produce full crowns using both alloys. After mounting the full crowns on the model, the model was attached to an articulator that was improved to simulate jaw movements through motor and cam mechanisms, and mechanical abrasion movements were continued for 6 and 12 hours. The myocardial differentiation rate of ES-D3 cells was slightly lower for Ag-20% In alloy than for Ag-Pd-Au-Cu alloy. No difference was noted in cell viability between ES-D3 and Balb/c-3T3 cells and the sample-free control group.The embryotoxicity of Ag-20% In alloy was tested by whole rat embryo culture, demonstrating that the embryos were normal without any significant difference in yolk sac diameters, anterior-posterior lengths, head lengths, numbers of somites, or amounts of protein compared with the control group.Thus, the embryotoxicity risk of the experimental indium-containing alloys was negligible.