RESUMO
The demand of bone graft materials has been increasing. Among various origins of bone graft materials, natural coral composed of up to 99% calcium carbonate was chosen and converted into hydroxyapatite (HA); silicon was then substituted into the HA. Then, the Si-HA was mixed with ß-tricalcium phosphate (TCP) in the ratios 100:0 (S100T0), 70:30 (S70T30), 60:40 (S60T40), and 50:50 (S50T50). The materials were implanted for four and eight weeks in a rat calvarial bone defect model (8 mm). The MBCPTM (HA:ß-TCP = 60:40, Biomatalante, Vigneux de Bretagne, France) was used as a control. After euthanasia, the bone tissue was analyzed by making histological slides. From the results, S60T40 showed the fastest bone regeneration in four weeks (p < 0.05). In addition, S60T40, S50T50, and MBCPTM showed significant new bone formation in eight weeks (p < 0.05). In conclusion, Si-HA/TCP showed potential as a bone graft material.
RESUMO
Oleanolic acid (OA), a pentacyclic triterpene acid, has been reported to possess inducing activity of hepatic metallothionein (MT). However, the mechanism underlying its effects is unknown. This study investigated the effects of OA on the regulation of MT expression in an in vitro model. OA that was added directly to Hepa-1c1c7 cells had no effect on MT induction. However, MT and its mRNA levels increased markedly when the Hepa-1c1c7 cells were cultured with the OA-treated conditioned media from the RAW 264.7 cells. Co-treating the RAW 264.7 cells with OA and pentoxifylline, a TNF-alpha synthesis inhibitor, resulted in a decrease in the effects of OA on the MT induction. In the OA-exposed RAW 264.7 cell cultures, production and mRNA levels of TNF-alpha and IL-6 were increased. However, the MT induction activity was inhibited when antibodies to TNF-alpha and/or IL-6 were added to the OA-treated conditioned media from the RAW 264.7 cells. These results suggest that the up-regulation of MT expression by OA was mediated by the TNF-alpha and IL-6 released from UA-activated macrophages.