与传统航拍相比,倾斜航拍作为一种新型的航拍方式,可以为三维城市建模提供更多的纹理数据支持,但是由于航拍倾斜角度较大,所获影像透视畸变明显,给倾斜航空影像间的匹配造成困难.本文利用Structure from Motion算法(简称SFM算法)对倾斜...与传统航拍相比,倾斜航拍作为一种新型的航拍方式,可以为三维城市建模提供更多的纹理数据支持,但是由于航拍倾斜角度较大,所获影像透视畸变明显,给倾斜航空影像间的匹配造成困难.本文利用Structure from Motion算法(简称SFM算法)对倾斜航空影像的相机姿态进行精确标定,并结合Patch-based Multi-view Stereo算法(简称PMVS算法)对标定影像进行密集匹配.结果表明,SFM算法对于倾斜航空影像的姿态标定具有较好的适用性,且通过PMVS算法能够得到大量具有颜色信息的三维点云数据,这些点云数据可直接用于三维场景重建.展开更多
Background Vascular endothelial growth factor （VEGF） is well known as a hypoxia-induced protein. That it markedly increased expression of VEGF and improvement of rat motor function after spinal cord injury suggested...Background Vascular endothelial growth factor （VEGF） is well known as a hypoxia-induced protein. That it markedly increased expression of VEGF and improvement of rat motor function after spinal cord injury suggested that VEGF could play a neuroprotective role in ischaemic tolerance. This study investigated whether vascular endothelial growth factor has direct neuroprotective effects on rat spinal cord neurons. Methods We employed primary cultures of embryonic rat spinal cord neurons, then administrated different concentrations of VEGF164 in the culture medium before hypoxia when the number of neurons was counted and the cell viability was detected by MTT. The neuronal apoptosis and expression of VEGF and its receptor genes were evaluated by terminal deoxynucleotidyl transferase mediated dUTP nick-end labelling （TUNEL） and immunohistochemistry. The VEGFR2/FLK-1 inhibitor, SU1498, was used to confirm whether the neuroprotective effect of VEGF was mediated through VEGFR2/Flk-1 receptors. Result In hypoxic conditions,the number and viability of neurons decreased progressively, while the number of TUNEL-positive cells increased along with the prolongation of hypoxic exposure. When the concentration of VEGF in cell culture medium reached 25 ng/ml, the cell viability increased 11% and neuronal apoptosis reduced to half, this effect was dose dependent and led to an approximately 25% increase in cell viability and about threefold decrease in TUNEL-positive cells at a maximally effective concentration of 100 ng/ml. In normal conditions, VEGF/Flk-1 but not VEGF/Flt-1 gene expressed at a low level： after hypoxia, the expression of VEGF/Flk-1, but not VEGF/Flt-1 was significantly increased. The protective effect of VEGF was blocked by the VEGFR2/Flk-1 receptor tyrosine kinase inhibitor, SU1498. Conclusions VEGF has direct neuroprotective effects on rat spinal cord neurons, which may be mediated in vitro through VEGFR2/Flk-1 receptors.展开更多
Background Porcine liver performing efficient physiological functions in the human body is prerequisite for successful liver xenotransplantation. However, the protein differences between pig and human remain largely u...Background Porcine liver performing efficient physiological functions in the human body is prerequisite for successful liver xenotransplantation. However, the protein differences between pig and human remain largely unexplored. Therefore we investigated the liver expression profile of a highly inbred minipig line. Methods A cDNA library was constructed from liver tissue of an inbred Banna minipig. Two hundred randomly selected clones were sequenced then analysed by BLAST programme. Results Alignments of the sequences showed 44% encoded previously known porcine genes. Among the 56% unknown genes, sequences of 72 clones had high similarities with known genes of other species and the similarities to human were mostly above 0.80. The other 40 clones showing no similarity to genes in National Centre for Biotechnology Information are newly discovered, expressed sequence tags specific to liver of inbred Banna minipig. Twenty-two of the 200 clones had full length encoding regions, 38 complete 5＇ terminal sequences and 140 complete 3＇ terminal sequences.Conclusion These newly discovered expression sequences may be an important resource for research involving physiological characteristics and medical usage of inbred pigs and contribute to matching studies in xenotransplantation.展开更多
文摘与传统航拍相比,倾斜航拍作为一种新型的航拍方式,可以为三维城市建模提供更多的纹理数据支持,但是由于航拍倾斜角度较大,所获影像透视畸变明显,给倾斜航空影像间的匹配造成困难.本文利用Structure from Motion算法(简称SFM算法)对倾斜航空影像的相机姿态进行精确标定,并结合Patch-based Multi-view Stereo算法(简称PMVS算法)对标定影像进行密集匹配.结果表明,SFM算法对于倾斜航空影像的姿态标定具有较好的适用性,且通过PMVS算法能够得到大量具有颜色信息的三维点云数据,这些点云数据可直接用于三维场景重建.
文摘Background Vascular endothelial growth factor （VEGF） is well known as a hypoxia-induced protein. That it markedly increased expression of VEGF and improvement of rat motor function after spinal cord injury suggested that VEGF could play a neuroprotective role in ischaemic tolerance. This study investigated whether vascular endothelial growth factor has direct neuroprotective effects on rat spinal cord neurons. Methods We employed primary cultures of embryonic rat spinal cord neurons, then administrated different concentrations of VEGF164 in the culture medium before hypoxia when the number of neurons was counted and the cell viability was detected by MTT. The neuronal apoptosis and expression of VEGF and its receptor genes were evaluated by terminal deoxynucleotidyl transferase mediated dUTP nick-end labelling （TUNEL） and immunohistochemistry. The VEGFR2/FLK-1 inhibitor, SU1498, was used to confirm whether the neuroprotective effect of VEGF was mediated through VEGFR2/Flk-1 receptors. Result In hypoxic conditions,the number and viability of neurons decreased progressively, while the number of TUNEL-positive cells increased along with the prolongation of hypoxic exposure. When the concentration of VEGF in cell culture medium reached 25 ng/ml, the cell viability increased 11% and neuronal apoptosis reduced to half, this effect was dose dependent and led to an approximately 25% increase in cell viability and about threefold decrease in TUNEL-positive cells at a maximally effective concentration of 100 ng/ml. In normal conditions, VEGF/Flk-1 but not VEGF/Flt-1 gene expressed at a low level： after hypoxia, the expression of VEGF/Flk-1, but not VEGF/Flt-1 was significantly increased. The protective effect of VEGF was blocked by the VEGFR2/Flk-1 receptor tyrosine kinase inhibitor, SU1498. Conclusions VEGF has direct neuroprotective effects on rat spinal cord neurons, which may be mediated in vitro through VEGFR2/Flk-1 receptors.
基金This study was supported by grants from the National Natural Science Foundation of China(No.30270679)National Basic Research Program of China(No.2003CB515504)National Basic Research Program of China(No.2004CCA01800).
文摘Background Porcine liver performing efficient physiological functions in the human body is prerequisite for successful liver xenotransplantation. However, the protein differences between pig and human remain largely unexplored. Therefore we investigated the liver expression profile of a highly inbred minipig line. Methods A cDNA library was constructed from liver tissue of an inbred Banna minipig. Two hundred randomly selected clones were sequenced then analysed by BLAST programme. Results Alignments of the sequences showed 44% encoded previously known porcine genes. Among the 56% unknown genes, sequences of 72 clones had high similarities with known genes of other species and the similarities to human were mostly above 0.80. The other 40 clones showing no similarity to genes in National Centre for Biotechnology Information are newly discovered, expressed sequence tags specific to liver of inbred Banna minipig. Twenty-two of the 200 clones had full length encoding regions, 38 complete 5＇ terminal sequences and 140 complete 3＇ terminal sequences.Conclusion These newly discovered expression sequences may be an important resource for research involving physiological characteristics and medical usage of inbred pigs and contribute to matching studies in xenotransplantation.
