Nitric oxide and prostaglandin E2 secretion in osteocytes induced by intermittent cyclic compressive force / 生物医学工程学杂志

This paper is aimed to investigate the effect of rest-inserted loading on the mechanosensitivity of osteocytes. In the investigation, cultured MLO-Y4 osteocyte-like cells were strained on cyclic compressive force (CCF) by the self-made compressive loading device. Then we observed the effect of different rest periods-inserted loading (5 s, 15 s, 30 s, respectively) on the mechanosensitivity of osteocytes. We then determined the levels of secreted nitric oxide (NO) and prostaglandin E2 (PGE2) by Griess method and enzyme linked immunosorbent assay (ELISA), respectively. We then stained the cytoskeleton F-actin using immunofluorescence. We found that the expressions of NO and PGE2 in rest-inserted strained groups (> 15 s) were significantly increased compared to those in the continuous strained group. And rest-inserted loading promoted the parallel alignment of stress fibers. It indicates that rest-inserted loading could promote the mechanosensitivity of osteocytes, and this might be related to the parallel alignment of stress fibers.

Influence of cryogenic treatment and age-hardening heat treatment on the microhardness of palladium-silver dental alloys / 华西口腔医学杂志

<p><b>OBJECTIVE</b>The purpose of this study was to investigate the influence of cryogenic treatment and age-hardening heat treatment on the micro-Vicker's hardness of palladium-silver dental alloys.</p><p><b>METHODS</b>A low-gold content dental casting alloy composed of Ag-Pd-Cu-Au was prepared for this study. Experimental specimens according to standard requirements were prepared following a standard dental laboratory casting procedure, cast specimens were heated to 900 degrees C and quenched in ice water. The specimens were then divided into 4 groups. They were subsequently subjected to different treatments, including age-hardening heat treatment, cryogenic treatment, heat treatment combined with cryogenic treatment. The non-treated group was used as control. The micro-Vicker's hardness value was examined. The significance of correlation was analyzed.</p><p><b>RESULTS</b>The micro-Vicker's hardness of specimens after age-hardening heat treatment, cryogenic treatment, heat treatment combined with cryogenic treatment increased by 129%, 13% and 141%, respectively, compared with that of the non-treated control group. Conclusion Age-hardening heat treatment and cryogenic treatment were effective in elevating the hardness of Ag-Pd-Cu-Au alloy.</p>