BACKGROUND：Studies have demonstrated that bone marrow stromal cells （BMSCs） undergo neuronal differentiation under certain in vitro conditions.However,very few inducers of BMSC differentiation have been used in cli...BACKGROUND：Studies have demonstrated that bone marrow stromal cells （BMSCs） undergo neuronal differentiation under certain in vitro conditions.However,very few inducers of BMSC differentiation have been used in clinical application.The effects of vascular endothelial growth factor （VEGF） on in vitro neuronal differentiation of BMSCs remain poorly understood.OBJECTIVE：To investigate the effect of VEGF on neuronal differentiation of BMSCs in vitro,and to determine the best VEGF concentration for experimental induction.DESIGN,TIME AND SETTING：In vitro comparative study was performed at the Central Laboratory and Laboratory of Male Reproductive Medicine,Shenzhen Hospital of Peking University from October 2008 to August 2009.MATERIALS：Recombinant human VEGF165 was purchased from Peprotech Asia,Rehovot,Israel.Neuron-specific enolase （NSE） was purchased from Beijing Biosynthesis Biotechnology,China.METHODS：BMSCs were harvested from adult Sprague Dawley rats.The passaged cells were pre-induced with 10 ng/mL basic fibroblast growth factor for 24 hours,followed by differentiation induction with 0,5,10,and 20 ng/mL VEGF,respectively.MAIN OUTCOME MEASURES：Morphological changes in BMSCs prior to and following VEGF induction.Expression of NSE following induction was determined by immunocytochemistry.RESULTS：Shrunken,round cells,with a strong refraction and thin bipolar or multipolar primary and secondary branches were observed 3 days after induction with 5,10,and 20 ng/mL VEGF.However,these changes were not observed in the control group.At 10 days after induction,the number of NSE-positive cells was greatest in the 10 ng/mL VEGF-treated group （P〈 0.05）.The number of NSE-positive cells was least in the control group at 3 and 10 days post-induction （P〈 0.05）.Moreover,the number of NSE-positive cells was greater at 10 days compared with at 3 days after induction （P〈 0.05）.CONCLUSION：Of the VEGF concentrations tested,10 ng/mL induced the greatest number of neuronal-like cells in vitro from BMSCs.展开更多
Considering about the effect of whitecaps and foams on pulse-limited Radar Altimeters, an improved algorithm of retrieving sea surface wind speed is proposed in this paper. Firstly, a four-layer dielectric model is es...Considering about the effect of whitecaps and foams on pulse-limited Radar Altimeters, an improved algorithm of retrieving sea surface wind speed is proposed in this paper. Firstly, a four-layer dielectric model is established in order to simulate an air-sea interface. Secondly, the microwave reflectivity of a sea surface covered by spray droplets and foams at 13.5 GHz is computed based on the established model. These computed results show that the effect of spray droplets and foams in high sea state conditions shall not be negligible on retrieving sea surface wind speed. Finally, compared with the analytical algorithms proposed by Zhao and some calculated results based on a three-layer dielectric model, an improved algorithm of retrieving sea surface wind speed is presented. At a high wind speed, the improved algorithm is in a better accord with some empirical algorithms such as Brown, Young ones and et al., and also in a good agreement with ZT and other algorithms at low wind speed. This new improved algorithm will be suitable not only for low wind speed retrieval, but also for high wind speed retrieval. Better accuracy and effectiveness of wind speed retrieval can also be obtained.展开更多
基金the Science and Technology Research Program of Shenzhen,No. 200802005
文摘BACKGROUND：Studies have demonstrated that bone marrow stromal cells （BMSCs） undergo neuronal differentiation under certain in vitro conditions.However,very few inducers of BMSC differentiation have been used in clinical application.The effects of vascular endothelial growth factor （VEGF） on in vitro neuronal differentiation of BMSCs remain poorly understood.OBJECTIVE：To investigate the effect of VEGF on neuronal differentiation of BMSCs in vitro,and to determine the best VEGF concentration for experimental induction.DESIGN,TIME AND SETTING：In vitro comparative study was performed at the Central Laboratory and Laboratory of Male Reproductive Medicine,Shenzhen Hospital of Peking University from October 2008 to August 2009.MATERIALS：Recombinant human VEGF165 was purchased from Peprotech Asia,Rehovot,Israel.Neuron-specific enolase （NSE） was purchased from Beijing Biosynthesis Biotechnology,China.METHODS：BMSCs were harvested from adult Sprague Dawley rats.The passaged cells were pre-induced with 10 ng/mL basic fibroblast growth factor for 24 hours,followed by differentiation induction with 0,5,10,and 20 ng/mL VEGF,respectively.MAIN OUTCOME MEASURES：Morphological changes in BMSCs prior to and following VEGF induction.Expression of NSE following induction was determined by immunocytochemistry.RESULTS：Shrunken,round cells,with a strong refraction and thin bipolar or multipolar primary and secondary branches were observed 3 days after induction with 5,10,and 20 ng/mL VEGF.However,these changes were not observed in the control group.At 10 days after induction,the number of NSE-positive cells was greatest in the 10 ng/mL VEGF-treated group （P〈 0.05）.The number of NSE-positive cells was least in the control group at 3 and 10 days post-induction （P〈 0.05）.Moreover,the number of NSE-positive cells was greater at 10 days compared with at 3 days after induction （P〈 0.05）.CONCLUSION：Of the VEGF concentrations tested,10 ng/mL induced the greatest number of neuronal-like cells in vitro from BMSCs.
文摘Considering about the effect of whitecaps and foams on pulse-limited Radar Altimeters, an improved algorithm of retrieving sea surface wind speed is proposed in this paper. Firstly, a four-layer dielectric model is established in order to simulate an air-sea interface. Secondly, the microwave reflectivity of a sea surface covered by spray droplets and foams at 13.5 GHz is computed based on the established model. These computed results show that the effect of spray droplets and foams in high sea state conditions shall not be negligible on retrieving sea surface wind speed. Finally, compared with the analytical algorithms proposed by Zhao and some calculated results based on a three-layer dielectric model, an improved algorithm of retrieving sea surface wind speed is presented. At a high wind speed, the improved algorithm is in a better accord with some empirical algorithms such as Brown, Young ones and et al., and also in a good agreement with ZT and other algorithms at low wind speed. This new improved algorithm will be suitable not only for low wind speed retrieval, but also for high wind speed retrieval. Better accuracy and effectiveness of wind speed retrieval can also be obtained.
