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Mineral trioxide aggregate (MTA), a commonly used endodontic repair material, is useful for both basic and clinical research, and the effect of MTA on osteoblast differentiation has been well-defined. However, the effects of MTA on osteoclastic bone resorption are not fully understood. Hence, the aim of this study is to examine the effect of MTA solution in the regulation of osteoclast bone-resorbing activity using osteoclasts formed in co-cultures of primary osteoblasts and bone marrow cells. MTA solution dose-dependently reduced the total area of pits formed by osteoclasts. The reduction of resorption induced by 20% MTA treatment was due to inhibition of osteoclastic bone-resorbing activity and had no effect on osteoclast number. A 20% MTA solution disrupted actin ring formation, a marker of osteoclastic bone resorption, by reducing phosphorylation and kinase activity of c-Src, and mRNA expressions of cathepsin K and mmp-9. A high concentration of MTA solution (50%) induced apoptosis of osteoclasts by increasing the expression of Bim, a member of the BH3-only (Bcl-2 homology) family of pro-apoptotic proteins. Taken together, our results suggest that MTA is a useful retrofilling material for several clinical situations because it both stimulates osteoblast differentiation and inhibits bone resorption.

Abstract-Effect of probucol, pantethine and their combinations on serum lipoprotein metabolism and on the incidence of atheromatous lesions in aorta and coronary artery was studied in cholesterol-fed rabbits.Probucol treatment (0.5% in diet) resulted in reducing HDL cholesterol and serum apo A-I levels significantly, while pantethine treatment (0.25%-0.75% in diet) tended to increase HDL cholesterol and serum apo A-I levels. Combined treatment with these two drugs showed a sig nificant prevention in the reduction of HDL cholesterol and serum apo A-I levels by probucol alone.Probucol or pantethine treatment reduced effectively (V) LDL cholesterol and serum apo B levels, and these effects were accelerated additively when the two drugs were given concurrently.Atheromatous lesions in aorta and coronary artery in cholesterol-fed rabbits were prevented by the treatment with probucol (0.5% in diet) or pantethine (0.75% in diet) for 24 weeks.The combined treatment with these two drugs showed more marked prevention than either drug alone.From these findings, it is concluded that the combined treatment of probucol with pantethine is effective for improvement of serum lipoprotein disorders and for prevention of the incidence of atheromatous lesions in aorta and coronary artery in cholesterol-fed rabbits.

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