Objective To develop a rapid method for construction of RNAi vector.Methods After inversely inserting the U6 and H1 polymerase Ⅲ promoters into the pBluescriptⅡ backbone vector,only with two short reverse complementary oligo nucleotides,the RNAi vector with one interference cassette could be constructed.Using two isoaudamers MunⅠ and EcoRⅠ with sticky ends,several cassettes could be fused together to form the ultimate multiple-site targeting RNAi vector.Using this method,we constructed RNAi vectors targeting green fluorescent protein(GFP) and firefly luciferase(LUC) gene separately or both for the test of knock down property of these vectors.Results Constructed single and two site targeting RNAi vectors got desirable knockdown effects,in which single site targeting vector could get about 90 percent knock down efficiency whereas two site targeting vector reached about 87.5 percent knock down efficiency either.Conclusion Our RNAi vector construction strategy is efficient and time-saving so that it can be used for knocking down several genes simultaneously in the same cell.

Objective To study the MR imaging features of intracranial subependymomas and to improve the knowledge more about it. Methods The imaging features of intracranial subependymomas in 17 cases proved pathologically were retrospectively analyzed, among which 11 cases were male and 6 cases were female, 16 cases had MR images and 1 case only had CT images.Results MR appearances of intracranial subependymomas were as follows :16 cases were all hyperintense relative to the normal grey matter on T2-weighted images and hypointense or isointense on T1-weighted images. 12 cases showed no enhancement or minimal enhancement after Gd-DTPA administration . 9 of 16 cases were located in lateral ventricle, 2 were in septum pellucidum, and the rest 5 were in fourth ventricle ,third ventricle ,prepontine cistern, right CPA and chiasmatic cistern respectively. In one case , CT showed isodensity and was enhanced in CE-CT,the lesion was situated in fourth ventricle. In all 17 cases, 11 were accompanied with microcystic structures. Conclusion Intracranial subependymomas are best delineated by MR imaging. The diagnosis of intracranial subependymomas should be considered when above findings are confronted.

Objective To observe the relationship between visual-spatial perception impairment and the characteristics of asymptomatic cerebral infarction (ACI). Methods After evaluating the cognitive impairment of 112 patients with ACI using the Revised Visual Retention Test (VRT), we compared the result of VRT test among different groups grouped by number, size and location of the cerebral infarction. Results The total score of the patients with ACI with correct answers in VRT was significantly lower than that of the controls (14.5?3.2 vs 22.8?3.3, P

Objective To evaluate changes of venous hemodynamics during laparoscopic cholecystectomy(LC).Methods A total of 25 cases of LC was included in the study.A Doppler ultrasonography of the lower limb veins was performed in all the patients to exclude those with abnormal veins or thrombosis.During the LC,the diameter and venous flow volume of the femoral vein were measured under Doppler ultrasonography.Measurements were obtained at three different times:after the induction of anesthesia but prior to the creation of the pneumoperitoneum,during the pneumoperitoneum,and after abdominal deflation but prior to the reversal of anesthesia.Results All the operations were successfully completed.The mean operation time was 45 min(range,30～70 min).No intraoperative hemorrhage or bile duct complications occurred.No conversion to open surgery was required.All the patients were dismissed from hospital on the first postoperative day.After the establishment of the pneumoperitoneum,the cross-sectional area of the femoral vein was increased from 0.94?0.18 cm2 to 1.12?0.23 cm2(q=3.919,P0.05).The venous flow was significantly increased from 7.62?0.72 cm3/s to 9.65?0.63 cm3/s(q=12.971,P

Objective To study the imaging characters of spinal teratomas.Methods 10 cases of spinal teratomas were analyzed with clinical and radiography. 8 cases intramedullary, 2 cases extramedullary. 10 cases had MR examination. Results The location of spinal teratomas in 5 cases was in lumbar, 3 cases in thorax, 1 case in thoracolumbar, 1 case in cervical. 7 cases were multicyst type, 3 cases were singlecyst type. 10 cases of MR image showed mix signal intensity. The contrast enhancement T 1WI with fat saturation presented disappear fat signal of spinal teratomas. The teratomas heterogeneous enhancement was found in 10 cases with MR examination. 3 cases lumbosacral area of spinal teratomas united tethercord. Conclusion Neuroradiological features of spinal teratomas has specific manifestation. The T 1WI fat saturation scan is a availability nicety method for spinal teratomas.

Objective To study and compare the clinical and MR imaging characteristics of common intracranial ring enhanced lesions.Methods MR imaging studies of 65 intracranial ring enhanced lesions were reviewed retrospectively. The lesions included 17 glioblastomas, 17 metastasises, 12 brain abscesses, 8 acoustic neurinomas, 7 craniopharyngiomas, 3 neurocysticercosises, 1 malignant lymphoma. All cases were confirmed by surgery and pathology. Results The ring enhancement of tumors presented heterogenous thickness of thick walls and irregular forms. Among them, the highly malignant tumors appeared very obviously heterogeneous thickness of the walls, especially the inner walls were uneven and coarse. While the ring enhancement of the non-tumor lesions usually were of homogeneous thickness of the walls, regular shapes and smooth inner walls. Conclusion The different patterns of intracranial ring enhanced lesions on MR can supply important diagnostic information. Combining the patients' history, age, location and the information of magnetic resonance imaging, we may make correct diagnosis.

Objective To study the MRI findings of spinal hemangioblastomas.Methods The MRI findings of spinal hemangioblastomas proved pathologically in 29 cases (20 males,9 females) were retrospectively reviewed.Results The lesions were single in 12 cases (41.4%) and multiple in 17 cases(58.6%).Seven patients combined with intracranial hemangioblastomas.On unenhanced MRI,36 tumors were isointense on T 1WI and T 2WI,16 were mixed iso-hypointense on T 1WI and mixed iso-hyperintense on T 2WI,one was hypointense on T 1WI and hyperintense on T 2WI.Small hemangioblastomas tended to be isointense on T 1WI and T 2WI.After contrast injection,all tumors enhanced markedly and homogenously with clear borders.21 tumors in 17 patients had associated vascular flow voids on T 2WI.40 tumors in 27 patients were associated with syringes or cysts.Conclusion Hemangioblastomas of the spinal cord are often multiple and in company with intracranial hemangioblastomas.The marked contrast enhancements with clear borders and associated vascular flow voids are the most important signs on MRI.

Objective To study the imaging findings of cerebral venous sinus occlusion and to improve the knowledge of this disease.Methods CT,MRI and DSA data in thirty six cases with cerebral venous sinous occlusion were retrospectively reviewed.There were 15 male and 21 female,ranged in age from 23 to 59 years old.Results On T_1WI and T_2WI,abnormal signals in cerebral parenchyma were found in 26 cases,of that there were brain hemorrhage with abnromal long T_1 and long T_2 signal in 16 cases,only abnromal long T_1 and long T_2 signal in 6 cases,cerebral ventrical enlargment in 4 cases and brain swelling in 4 cases.The abnormal venous enhancement was found in 25 cases on contrast-enhanced MRI.On CT scan,low density in cerebral parenchyma was found in 10 cases,it might be edema or ischemia,astime goes by,the density of cerebral venous sinus became slightly high density to isodensity.DSA showed dural sinus occlusion includingsuperior sagittal sinus in 15 cases,transverse sinus in 8 cases,sigmoid sinus in 7 cases,straight sinus in 4 cases and inferior sagittal sinus in 2 cases.Conclusion The venous sinus occlusive disease is distinctively different from arterial occlusive disease.CT and MR imaging is very important in diagnosing the cerebral venous sinus occlusive disease,but DSA is still the gold standard.

Objective To establish a new automatic lung segmentation method in order to deal with the omission of pleural nodules and pulmonary vessels. Methods Lung parenchyma were extracted from chest CT images with the inversed operation of 2D region growing and connected area classification, then the contours and locating the contour points were traced with scan line searching. Finally, the parameters of lung contour points were analyzed to locate the contours distorted by nodules, and curve spline was used to correct distorted contours. Results The experimental results of many sets of CT images verified that the technique proposed was effective. The comparison with other contour correction algorithm verified that line searching contour correction was superior. Conclusion The proposed algorithm includes tumors in the segment results, and confirms the integrality, veracity, real-time quality of this auto-segmentation method.