AIM: To construct a differentially-expressed gene subtracted cDNA library from two colorectal carcinoma (CRC) cell lines with different metastatic phenotypes by suppression subtractive hybridization.METHODS: Two cell ...AIM: To construct a differentially-expressed gene subtracted cDNA library from two colorectal carcinoma (CRC) cell lines with different metastatic phenotypes by suppression subtractive hybridization.METHODS: Two cell lines of human CRC from the same patient were used. SW620 cell line showing highly metastatic potential was regarded as tester in the forward subtractive hybridization, while SW480 cell line with lowly metastatic potential was treated as tester in the reverse hybridization. Suppression subtractive hybridization (SSH) was employed to obtain cDNA fragments of differentially expressed genes for the metastasis of CRC. These fragments were ligated with T vectors, screened through the blue-white screening system to establish cDNA library.RESULTS: After the blue-white screening, 235 white clones were picked out from the positive-going hybridization and 232 from the reverse. PCR results showed that 200-700 bp inserts were seen in 98% and 91% clones from the forward and reverse hybridizations, respectively.CONCLUSIONS: A subtractive cDNA library of differentially expressed genes specific for metastasis of CRC can be constructed with SSH and T/A cloning techniques.展开更多
In this paper we develop a general exact fan-beam reconstruction algorithm for free-form trajectories not only closed but also unclosed,based on the fan-beam reconstruction formula recently developed by Noo et al.. A ...In this paper we develop a general exact fan-beam reconstruction algorithm for free-form trajectories not only closed but also unclosed,based on the fan-beam reconstruction formula recently developed by Noo et al.. A mathematical proof is then provided with the geometrical explanation of equi-spatial detectors. With this algorithm we can obtain exact region of interest (ROI) reconstruction if and only if every projecting line passing through the ROI intersects the free-form source trajectory,when the projections are not truncated. Furthermore,under the condi- tion that the source-to-detectors distance changes slowly enough relative to the length itself,we obtain a very good approximate reconstruction algorithm,which is the same as the algorithm of the circular trajectory except that the source-to-detectors distance is a function of the rotation angle. Then the algorithms are tested using the Shepp-Logan phantom and the experiment shows that the algorithms can get perfect numerical results.展开更多
Based on an incompressible model, by using the large stain theory, the contact of a rubber wedge with a rigid notch is analyzed by the asymptotic method. The problem is treated as a symmetric case, and the contact...Based on an incompressible model, by using the large stain theory, the contact of a rubber wedge with a rigid notch is analyzed by the asymptotic method. The problem is treated as a symmetric case, and the contact surface is smooth. The stress and strain ?eld near the apex of the rubber wedge is shown to be singular, and the angular distributions of stress and strain are obtained. Two important parameters t and tˉ are introduced to attain the conclusions. The result shows that the singular exponent order of stress ?eld is ln r.展开更多
In the past spring and summer, the burst of SARS crisis had a negative influence on people's daily life and enterprises'business. Under the impact of SARS, leaders of enterprises had personally known more of a...In the past spring and summer, the burst of SARS crisis had a negative influence on people's daily life and enterprises'business. Under the impact of SARS, leaders of enterprises had personally known more of a word——crisis, and at the same time they had thought of another concept——crisis management. But if we try to comorehend it from another point of view.展开更多
基金Supported by the Military Medical Foundation of China,No.01MA128
文摘AIM: To construct a differentially-expressed gene subtracted cDNA library from two colorectal carcinoma (CRC) cell lines with different metastatic phenotypes by suppression subtractive hybridization.METHODS: Two cell lines of human CRC from the same patient were used. SW620 cell line showing highly metastatic potential was regarded as tester in the forward subtractive hybridization, while SW480 cell line with lowly metastatic potential was treated as tester in the reverse hybridization. Suppression subtractive hybridization (SSH) was employed to obtain cDNA fragments of differentially expressed genes for the metastasis of CRC. These fragments were ligated with T vectors, screened through the blue-white screening system to establish cDNA library.RESULTS: After the blue-white screening, 235 white clones were picked out from the positive-going hybridization and 232 from the reverse. PCR results showed that 200-700 bp inserts were seen in 98% and 91% clones from the forward and reverse hybridizations, respectively.CONCLUSIONS: A subtractive cDNA library of differentially expressed genes specific for metastasis of CRC can be constructed with SSH and T/A cloning techniques.
基金Supported by a grant from the Ph.D. Programs Foundation of Ministry of Education of China (No.20030003074) and the National Natural Science Foundation of China (No.10135040).
文摘In this paper we develop a general exact fan-beam reconstruction algorithm for free-form trajectories not only closed but also unclosed,based on the fan-beam reconstruction formula recently developed by Noo et al.. A mathematical proof is then provided with the geometrical explanation of equi-spatial detectors. With this algorithm we can obtain exact region of interest (ROI) reconstruction if and only if every projecting line passing through the ROI intersects the free-form source trajectory,when the projections are not truncated. Furthermore,under the condi- tion that the source-to-detectors distance changes slowly enough relative to the length itself,we obtain a very good approximate reconstruction algorithm,which is the same as the algorithm of the circular trajectory except that the source-to-detectors distance is a function of the rotation angle. Then the algorithms are tested using the Shepp-Logan phantom and the experiment shows that the algorithms can get perfect numerical results.
基金Project supported by the National Natural Science Foundation of China (Nos. 19572001 and 19772001).
文摘Based on an incompressible model, by using the large stain theory, the contact of a rubber wedge with a rigid notch is analyzed by the asymptotic method. The problem is treated as a symmetric case, and the contact surface is smooth. The stress and strain ?eld near the apex of the rubber wedge is shown to be singular, and the angular distributions of stress and strain are obtained. Two important parameters t and tˉ are introduced to attain the conclusions. The result shows that the singular exponent order of stress ?eld is ln r.
文摘In the past spring and summer, the burst of SARS crisis had a negative influence on people's daily life and enterprises'business. Under the impact of SARS, leaders of enterprises had personally known more of a word——crisis, and at the same time they had thought of another concept——crisis management. But if we try to comorehend it from another point of view.
