Two-way choice is the main way for the seven-year-program clinical medical students and postgraduate supervisors.This article analyzes the influence factors and shortages of two-way choice for postgraduate supervisors and seven-year-program clinical medical students.This investigation discovers that the supervisor's abilities of research,teaching and clinical and their personal magnetism are important and key factors.The students' gender,character,hobbies and interests and the familiarity to profession are the secondary factors.The other factors that include employment status,the level of income and the advice of parents and friends also have influence on two-way choice for postgraduate supervisors and seven-year-program clinical medical students.In order to further improve the tow-way choice,the author gives some suggestions,including introducing profession and the scientific researches of supervisors in advance,encouraging the face-to-face communication between students and supervisors,promoting multiple profession choices and giving some aids to the students for choosing the supervisors.

Objective　This study was To investigate the incidence rate of Cockett syndrome and relationship between Cockett syndrome and varicose veins and deep venous incompetence of the left lower extremities.Methods　73 patients(100 legs) with varicose veins of the lower extremities were investigated by descending deep venography and iliography preoperatively.Results　There were 35(47.9%) cases with abnormalities of the left common iliac vein (ALCIV)in all the cases.There were 31 cases with this conditions in the patients with varicose veins of the left or both lower extremity.While in the patients with varicose veins of the only right lower extremity,there were only 4 cases with ALCIV.In contrast,there was a significant difference between groups(χ2=9.8641,P=0.0017).In the patients with ALCIV,14 cases with Ⅲ or Ⅳ grade of deep venous incomptence were found, and only 6 cases with deep venous incompetence in the patients without ALCIV.There was a significant difference(χ2=5.3688,P=0.0205).Conclusion　Cockett's syndrome frequently occurs in varicose veins of the left lower extremity.There is a relationship between them.Cockett's syndrome might be one of the causes for the deep venous incompetence of the left leg.

Pedicle screw fixation is widely used in spine surgery, which allows 3?dimensional fixation with a more rigid construct and permits a shorter fusion length. However, conventional pedicle screw fixation has some drawbacks, including signifi?cant muscle dissection for the exposure of bone marks. Although percutaneous pedicle screw technique can compensate for above defects, it requires an additional approach for decompression and bone graft insertion. Besides, the percutaneous pedicle screw technique depends on intraoperative multiplanar fluoroscopy, which results in high risk of radiation exposure of the surgeons and patients. Screw loosening is a well?known complication, especially in osteoporosis patients. Several methods can enhance screw stability, for example, modifying screw design and augmenting vertebral bodies with reinforcing materials that can improve the structural capacity of the deteriorated tissue, however, they also have some disadvantages. Although we can enhance bone?screw by modifying screw design, it is not useful in severe osteoporosis patients. At the same time, bone cement can increase pedicle screw axial pullout strength and fatigue resistance, however, it is associated with a number of inherent disadvantages such as its high exothermic polymerizing temperature, toxicity of the monomer, and risk of leakage to the spinal canal. Santoni et al. intro?duced cortical bone trajectory (CBT) for lumbar pedicle screw with a new screw design that is shorter and smaller in diameter which has been proposed to maximize the thread contact with this higher density bone surface. In addition, the CBT technique fol?lows a caudocephalad path sagittally and a laterally directed path in the transverse plane, engaging only cortical bone in the pedi?cle without the involvement of the vertebral body trabecular space. Finally, the screw insertion point of this technique locates around lateral pars, enabling less tissue dissection. Therefore, it can be an alternative approach to enhance screw fixation strength, and it may rescue failed pedicle screw and be used in minimally invasive spine surgery.

Objective To investigate the alkaloidal constituents of Nauclea officinalis, an anti-inflammatory and antibacterial traditional Chinese herb. Methods The alkaloids were isolated and purified by silica gel, Sephadex LH20, and C-18 ODS column chromatography repeatedly, and their structures were identified by spectral analysis. Results Eleven alkaloids were isolated from the stems of N. officinalis and their structures were identified as angustoline (Ⅰ), 19-O-ethylangustoline (Ⅱ), 3-S-3, 4-dihydroangustoline (Ⅲ), 3-R-3, 4-dihydroangustoline (Ⅳ), naucleamide A (Ⅴ), strictosamide (Ⅵ), vincosamide (Ⅶ), 6′-acetyl-strictosamide (Ⅷ), 2′-acetyl-strictosamide (Ⅸ), pumiloside (Ⅹ), 3-epi-pumiloside (Ⅺ). Conclusion Compounds Ⅰ-Ⅺ are isolated from this plant for the first time.

Objective To investigate the effects ofdocosahexenoic acid (DHA) on large conductance Ca2+-activated K+ (BK) channels in normal retinal artery smooth muscle cells (RASMCs).Methods Cultured human RASMCs (6 th-8 th generations) were used to patch clamp experiment.The open probabihties (NP0) in BK channels with different concentrations (0.0,1.0,3.0,5.0,7.5,10.0 μmol/L) of DHA were recorded by patch clamp technique in single channel configuration.RASMCs were intervened by different concentrations (0.0,1.0,5.0 μmol/L) of DHA as control group,low and high doses of DHA groups,respectively.The protein expressions of β subunit of BK channels in RASMCs from three groups were measured by Western blot.Results The NP0 of BK channels were 0.044 4±0.001 2,0.081 2±0.004 2,0.209 0±0.006 1,0.310 5±0.005 3,0.465 0±0.007 8 and 0.497 7±0.014 5 with perfusate of 0.0,1.0,3.0,5.0,7.5,10.0 μtmol/L DHA.DHA activated BK channels in a dose-dependent manner (F=2.621,P＜0.05).There was no significant difference in the protein expression of control group,low and high doses of DHA groups (F=1 1.657,P＞0.05).Conclusion DHA can directly activate BK channels,no increasing in subunit expression of BK channels.

Objective To study the antitumor activities of extract from Ligia exotica(Roux).Methods The dried powder of total Ligia exotica(Roux) was extracted by 37 ℃ water.The solution was concentrated in vacuum,and then was freeze-dried to afford crude extract.The inhibitory effect of the extract on tumor cells proliferation was assayed by MTT method,and transplant tumor model of sarcoma 180(S180) was used.Results The extract from Ligia exotica displayed obvious proliferation inhibitory effect on HeLa,7901,NCI cells,and no growth inhibitory effect on 929 cells in vitro.After administration at the doses of 0.25,0.50,1.00 g?kg-1,ip,for 7d in tumor-bearing mice with S180,The extract caused 26.9 %,45.3 %,64.6 % inhibition rates,respectively.Conclusion The extract from Ligia exotica showed significant antitumor activity.

Objective The aim of this study was to provide methods for predicting ideal trajectory and position of C1 lateral mass screw (C1 LMS)from plain radiographs.Methods A total of 40 consecutive subjects (with 79 screws)who had undergone C1 LMS placement were enrolled.To evaluate the C1 LMS position,the positions of screw head and tips on anteroposterior radiographs,screw length,and height on lateral radiograph were graded as 0°,Ⅰ°,and Ⅱ°,respectively.On the postoperative computed tomography images,the lateral mass (LM) perforation,screw-thread engagement percent(%),bicortical fixation,extruded screw length,and violation of adjacent joints were analyzed. Results Screws with tip located medial to LM(tip 0)showed LMperforation in all cases.Polyaxial head located within the LM(head 0)or crossing the lateral margin of the LM(head Ⅰ)showed no LMperforation.Screw-thread engagement percent was the highest with head Ⅰ-tip Ⅰ (medial half of LM)position (97.6%),followed by head 0-tip Ⅰ (90.5%)and head Ⅰ-tip Ⅱ (lateral half of LM)(86.4%). Screws longer than the posterior half of C1 anterior arch (AA)showed bicortical fixation in all cases with mean extruded screw length of 1.9 mm.Adjacent joint was not violated in 98%,with the screw height below half of C1 AA.Conclusion On an anteroposterior radiograph, a C1 LMS with the screw head located on the lateral margin of the LMand with the screw tip in the medial half of the LMresulted in the safest and longest trajectory.On lateral radiograph,a screw tip that is placed within the anterior-inferior quadrant of the C1 AA results in safe bicorti-cal fixation without injury to the adjacent structures.These plain radiographic findings may be helpful bothpostoperatively and intraoperatively for assessing the trajectory and length of the screw.

Since Hosobuchi first found that spinal cord stimulation had the effect of significantly increasing cerebral blood flow (CBF) more than two decades ago, spinal cord stimulation had attracted wide attention in the field of treating cerebral ischemia. A large number of animal and clinical studies have been performed in this field, which make it another research focus following thrombolysis and interventional therapy. This article reviews the research history, mechanisms, and current status of clinical applications of spinal cord stimulation in cerebral ischemia protection.

Objective:To study the influence of r-tPA and urokinase in curative effect and thrombolysis time on patients with acute and severe pulmonary embolism after interventional thrombectomy .Methods:After reviewing and analyzing the clinical data of 19 acute and severe pulmonary embolism patients , we classified them into two groups in accordance with the application of r-tPA and urokinase to compare the changes of their heart rate , blood pressure , pulmonary arterial pressure , arterial partial pressure of oxygen and hemachrome before and after thrombolysis , as well as the thrombolysis effect time the two groups took.Results: The heart rate, blood pressure, pulmonary arterial pressure , arterial partial pressure of oxygen of the patients in both groups gained remarkable improvement after operation ( P<0 .05 );the pulmonary arterial pressure of the r-tPA patient group dropped but not significantly compared with that before operation ( P>0.05); the pulmonary arterial pressure of the urokinase patient group dropped significantly compared with that study before operation ( P<0.05 ); the hemachrome of both patient groups did not significantly drop after operation ( P>0 .05 );the thrombolysis effect time by adop-ting r-tPA was remarkably shorter than that caused in thrombolysis by adopting urokinase ( P<0 .05 ) . Conclusion: Both r-tPA and urokinase are effective in interventional thrombolysis for acute and severe pulmonary embolism .However , r-tPA could significantly shorten the time caused in thrombolysis without increasing any bleeding risk.