-Recent in vitro and in vivo animal studies have reported that statin, a cholesterol-lowering drug, stimulate osteogenic differentiation. In the present study, we investigated the effect of simvastatin on osteogenic and adipogenic differentiation in primarily cultured human adipose-derived stem cells (hADSCs). The simvastatin treatment significantly increased the positive cell numbers in alkaline phosphatase and von Kossa staining, and enhanced the expression levels of bone morphogenic protein (BMP)-2, core binding factor alpha 1 (cbfa1), collgen type I and osteonectin mRNAs. Lastly, hADSCs were cultured in the adipogenic media with or without simvastatin to examine the effect of simvastatin on adipogenic differentiation. In the RT-PCR analysis, there were notable decreases in mRNA expression of aP1, C/EBP-α and PPAR-γ in hADSCs cultivated in simvastatin-added medium, compared to those in simvastatin-free medium. It suggests that the adipogenic differentiation was significantly inhibited by simvastatin treatment. These observations indicate that simvastatin induces osteogenic differentiation and suppresses adipogenic differentiation in hADSCs.
Experiments performed for negatively-refracted bulk shear waves in elastic media have been reported in literature, not for negatively-refracted guided shear waves in a plate. In this work, we present the negatively-refracted guided shear-horizontal wave experiment results in a thin Phononic Crystal (PC) plate. An interesting feature with negative refraction experiments in a plate, compared with those in a bulk medium, is that one can measure full wave field in a nominal base plate as soon as the negatively-refracted wave exists from a PC plate. Therefore, the actual wave path in the nominal plate can be visualized by the present experiment. For successful experiments, among others, the use of proper transducers is important. In particular, pure shear-horizontal wave generating transducers with narrow beam width are preferred. Here, we employed PSA-OPMT's (Planar Solenoid Array Orientation-adjustable Patch-type Magnetostrcitve Transducers) for wave generation and measurement. The negative refraction angle estimated from the experiments is shown to be in good agreement with the theoretically calculated values through Snell's law. For instance, the experimentally-determined refraction angle is -11.35 degree at the frequency of 220 kHz and it differs within 10% from the theoretical value, -12.67 degree.
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