ABSTRACT Purpose: To observe the mechanism of prepared Radix Rehmanniainon combined with Radix Astragali in treating osteoporosis. Methods: Osteoporosis rat model was established by bilateral ovariectomy combined with low-calcium diet feeding. Bone mineral density was measured by bone densitometer. Bone metabolism markers in serum were detected by enzyme linked immunosorbent assay (ELISA), bone tissue structure was observed by hematoxylin-eosin staining, and the effect of prepared Radix Rehmanniainon combined with Radix Astragali on PI3K-AKT signaling pathway was investigated by immunohistochemistry and reverse transcription polymerase chain reaction. Results: Compared with the model group, the bone tissue structure and imbalance of bone metabolism were improved, and the bone mineral density was significantly increased in the prepared Radix Rehmanniainon combined with Radix Astragali groups. After intervention with prepared Radix Rehmanniainon combined with Radix Astragali, the positive expression of PIK3CA and Akt1 in rat bone tissue was enhanced, and the expression levels of Akt1 mRNA were significantly increased. Conclusions: Prepared Radix Rehmanniainon combined with Radix Astragali may treat osteoporosis by activating PI3K/AKT pathway.

ABSTRACT Purpose To study effects of Rehmannia glutinosa polysaccharides (RGP) on bone tissue structure and skeletal muscle atrophy in rats with disuse. Methods A rat model of disuse osteoporosis combined with muscle atrophy was established by removing the bilateral ovaries of rats and fixing their hind limbs for a long time. Forty SD rats were administered intragastrically for 12 weeks. The bone histomorphometry parameters and the level of oxidative stress were measured. In addition, the changes of muscle atrophy F-box (MAFbx), muscle RING-finger protein-1 (MuRF1), forkhead box O1 (FOXO1) mRNA expression in skeletal muscle of rats were observed. Results RGP significantly increased the percentage of fluorescence perimeter and bone mineralization deposition rate of the second lumbar vertebrae of rats. It also significantly increased the wet weight ratio and muscle fiber cross-sectional area of the gastrocnemius muscle of rats. At the same time, RGP significantly increased the levels of super oxide dismutase (SOD) and catalase (CAT) in the skeletal muscle of rats, and reduced the content of malondialdehyde (MDA). Rehmannia glutinosa polysaccharides also significantly reduced the expression levels of FOXO1, MAFbx and MuRF1 mRNA in rat skeletal muscle. Conclusions RGP could improve the bone structure of osteoporotic rats. It could also improve muscle that atrophy may be related to the inhibition of FOXO1-mediated ubiquitin-proteasome pathway.

Abstract Purpose: To investigate inhibitory effect of Astragalus polysaccharide (APS) on osteoporosis in ovariectomized rats by regulating FoxO3a/Wnt2 signaling pathway. Methods: Postmenopausal osteoporosis (PMOP) animal model was developed by excising the bilateral ovaries of rats. The model rats were administered with APS (200 mg/kg, 400 mg/kg, 800 mg/kg) by intragastric administration once daily for 12 weeks. Bone density, bone metabolism index and oxidative stress index were measured in all groups. Furthermore, the regulation of APS of FoxO3a / Wnt2 signaling pathway was observed. Results: APS has an estrogen-like effect, which can increase bone mass, lower serum ALP and BGP values, increase blood calcium content, and increase bone density of the femur and vertebrae in rats. At the same time, APS can increase the bone mineral content of the femur, increase the maximum stress, maximum load and elastic modulus of the ovariectomized rats, improve oxidative stress in rats by increasing the gene expression of β-catenin and Wnt2 mRNA and inhibiting the gene expression of FoxO3a mRNA. Conclusion: Astragalus polysaccharide can effectively alleviate oxidative stress-mediated osteoporosis in ovariectomized rats, which may be related to its regulation of FoxO3a/Wnt2/β-catenin pathway.

To explore the deformation mechanisms of a new composite extrusion including extrusion and successive shear subsequently which is shorten "ES", Three dimensional finite element modeling of grain refinements for magnesium alloys by ES process has been researched. The ES die have been designed and manufactured and installed to the horizontal extruder. Finite element software DEFORM TM-3D to investigate the plastic deformation behaviors of magnesium alloy during extrusion-shear has been employed. The extrusion loads and temperatures distribution of billets and maximum extrusion forces have been obtained from simulation results. From the simulation results it is clear that evolutions of extrusion loads curve and effective stresses and temperatures can be divided into three stages. ES process has been applied to fabricate AZ31 magnesium alloy rod at preheat temperature of 420ºC with extrusion speed of 20 mm/s. The results proved that the ES process is a formality method for magnesium suitable for large scale industrial application. The microstructures of AZ31 magnesium alloy along the longitudinal section of rods have been sampled and examined and observed. Fine grained microstructures can be observed throughout longitudinal section of extruded rod. The researches results show that ES process would cause severe plastic deformation and improve the dynamic recrystallization of AZ31 magnesium alloy. The simulation results and calculated Zener-Hollomon parameters showed that the grains of magnesium would be refined gradually during ES process.