Problem-based learning (PBL) was carried out in general practice residency training program.Interview was used to evaluate the teaching performance.A total of 22 teachers and 198 students participated in evaluations.Among the teachers,17 (77％) were quite satisfied and 5 (23％) relatively satisfied.The overall satisfaction rates of teachers,problems and problem solutions were 87％,75％ and 91％ respectively. PBL stimulated the interests of students and was conducive for the combination of theoretical and practical knowledge.And it might improve the thinking ability of students and would be a good teaching method in general medicine residency training.

Objective: To investigate the inhibitory effects of chitosan oligosaccharide on tumor growth in vivo. Methods: Murine tumor cell line H22 was inoculated into. Then different doses of chitosan oligosaccharide were injected into the mice-bearing H22 liver carcinoma, IL-2 and IFN-? in the sera were measured by ELISA assay. The in vitro anti-proliferation activity of chitosan oligosaccharide on the lung carcinoma LH-7 cells was evaluated by MTT assay. Results: Chitosan oligosaccharide inhibited in vivo the growth of H22 tumor cells,with increasing the content of IL-2 and IFN-? in sera of the tumor-bearing mice. The weight of spleen and thymus of the mice were increased when compared with those of control group; tissue necrosis was observed in the tumor in situ; chitosan oligosaccharide also inhibited the growth of LH-7 cells in vitro. The inhibitory effect was shown in a concentration dependent pattern, but not correrlated with incubation time. The early characteristics of apoptosis of LH-7 cell could be observed under the transmission electronic microscopy. Conclusion: Chitosan oligosaccharide inhibits proliferation of tumor and improves immunity function of the hosts, and might induce apoptosis of LH-7 cells.

One hundred and forty-four medical students were enrolled in the study, the participants were randomly divided into experimental group and control group with 72 in each. All students attended the theoretical lecture of general medicine. Students in experimental group took part in the extracurricular teaching activities including the nutritional course and practice, the clinical case study and problem based learning ( PBL), students in control group did not have the extracurricular activities. The results showed that although there was no difference in general testing scores between two groups, the problem solving ability and assay-writing ability of experimental group were significantly higher than those of control group.

Objective:To explore the arsenic trioxide (As 2O 3)-induced apoptosis of human neuroblastoma cells (SH-SY5Y cells) and the protection mechanisms of folic acid (FA) and vitamin B 12 (VB 12). Methods:SH-SY5Y cells were cultured in vitro and divided into six groups by group design: control group (normal cultured), arsenic exposed group (10.00 μmol/L As 2O 3), FA intervention group (0.30 mmol/L FA + 10.00 μmol/L As 2O 3), VB 12 intervention group (0.06 mmol/L VB 12 + 10.00 μmol/L As 2O 3), combined intervention group (0.30 mmol/L FA + 0.06 mmol/L VB 12 + 10.00 μmol/L As 2O 3) and reagent control group (0.30 mmol/L FA + 0.06 mmol/L VB 12). Cells in each group were cultured for 24 h ( n = 3). Flow cytometry was used to determine the apoptosis rate of cells in each group. Transmission electron microscopy was used to observe the ultrastructural changes of the cells. The expression levels of mRNA and protein of apoptosis-related indicator B-cell lymphoma-2 (Bcl-2) and Bcl-2 associated X (Bax) were detected by fluorescence quantitative PCR and Western blotting. The activity of cysteinyl aspartate specific proteinase (Caspase) 3 was detected by luminescent assay. The above indicators were statistically analyzed. Results:There was statistically significant difference in the apoptosis rate among different groups ( F = 213.036, P < 0.05). The apoptosis rate in arsenic exposed group [(44.43 ± 3.54)%] was higher than that in control, FA intervention, VB 12 intervention, and combined intervention groups [(1.80 ± 0.06)%, (14.37 ± 0.13)%, (19.10 ± 1.56)%, (17.11 ± 2.34)%, P < 0.05]. Under transmission electron microscope, the apoptotic bodies, mitochondria swelling and degeneration, chromatin agglutination were observed in SH-SY5Y cells exposed to arsenic. The morphological and organelle changes of SH-SY5Y cells were significantly improved after respective and combined intervention of FA and VB 12. The expression levels of Bcl-2, Bax mRNA and protein were significantly different among different groups ( F = 5.178, 7.169, 6.142, 9.194, P < 0.05). The expression level of Bcl-2 protein in arsenic exposed group was lower than that in control group ( P < 0.05), and the expression levels of Bax mRNA and protein were higher than those in control group ( P < 0.05). The expression levels of Bcl-2 mRNA and protein in FA intervention group and combined intervention group were higher than those in arsenic exposed group ( P < 0.05), and Bcl-2 mRNA expression level in VB 12 intervention group was higher than that in arsenic exposed group ( P < 0.05). The expression levels of Bax mRNA and protein in FA intervention, VB 12 intervention and combined intervention groups were lower than those in arsenic exposed group ( P < 0.05). There were statistically significant differences in Caspase 3 activity among different groups ( F = 84.604, P < 0.05). Caspase 3 activity in arsenic exposed group was significantly higher than those in control, FA intervention, VB 12 intervention, and combined intervention groups ( P < 0.05). Conclusions:Arsenic exposure can lead to apoptosis and ultrastructural changes of SH-SY5Y cells. FA and VB 12 may effectively inhibit apoptosis through regulating Bcl-2/Bax pathway and decrease Caspase 3 activity, thus playing a protective role on nerve cells.

OBJECTIVETo explore the changes of anticancer efficiency of 5'-deoxy-5-fluorouridine (5'-DFUR) and 5-fluorouracil (5-Fu) in colorectal cancer cell line HT29 and LS174T cells after transfection of thymidine phosphorylase (TP) cDNA with a lentiviral vector.

METHODSTP cDNA was transfected into human colorectal cancer cell lines HT29 and LS174T with the lentiviral vector pLenti6.3-MCS-IRES2-EGFP, and the transfection efficiency of the two cell lines passed 5 generations was analyzed by flow cytometry. The expression of TP protein and the relative quantitative expression of TP mRNA in these 2 cell lines were detected by Western blot and RT-PCR, respectively. The 50% inhibitory concentration (IC50) of 5'-DFUR and 5-Fu in both HT29 and LS174T parent cells and TP-transfected cells were assessed by MTS assay. Finally, the concentration of converted 5-Fu was detected by high performance liquid chromatography (HPLC) either in the medium containing a series of concentrations of 5'-DFUR, in which HT29/HT29-TP or LS174T/LS174T-TP cells were cultured, or in the cell culture lysates.

RESULTSThe HT29 and LS174T cells transfected with human TP cDNA were monitored for 5 generations, and their transfection efficiency was about 95.0%. Immunohistochemical staining showed that both the parent cells and TP-transfected HT29 and LS174T cells were TP-positive, while vector-transfected cells were TP-negative. Western blotting showed that the TP protein expression in HT29-TP and LS174T-TP cells were significantly increased compared with that in their parents cells. The relative quantity (RQ) values of TP mRNA in HT29-TP and LS174T-TP cells were 8.45 ± 0.15 and 2 615.02 ± 253.97, respectively, which were significantly higher than that in their parents cells (P < 0.01). The IC50 values of 5'-DFUR on HT29-TP cells and its parents cell were (14.33 ± 0.74) µmol/L and (707.66 ± 5.66) µmol/L, respectively (P < 0.05), while (0.59 ± 0.11) µmol/L in LS174T-TP cells and (239.20 ± 21.83) µmol/L in its parent cells, respectively (P < 0.05). The IC50 values of 5-Fu of HT29-TP cells and its parents cells were (5.42 ± 0.75) µmol/L and (14.19 ± 0.97) µmol/L, respectively (P < 0.05), while (4.41 ± 0.96)µmol/L in LS174T-TP cells and (16.42 ± 2.12)µmol/L in its parents cells, respectively (P < 0.05). The HPLC results showed that the 5-Fu concentration detected from media contained a series of concentrations of 5'-DFUR for culturing HT29-TP and LS174T-TP cells were 12.2 to 28.7-folds and 13.1 to 23.6-folds, respectively, higher than that in their parents cells, (P < 0.01 for all). Otherwise, just a little of 5-Fu was detected in the two TP-transfected cells lysate, about 0.9% to 4.2% of 5-Fu detected in the media of the same cultured cells, whereas no 5-Fu was detected in the two parent cell lysates.

CONCLUSIONSTransfection of TP cDNA into colorectal cancer cell lines HT29 and LS174T with lentiviral vector can improve the expression of both TP mRNA and TP protein levels in passaged cells, enhance the conversion of 5-Fu from 5'-DFUR in the medium, and result in an enhanced anticancer effect on these two cell lines.

Antineoplastic Agents ; pharmacology ; Cell Line ; Cell Line, Tumor ; Colorectal Neoplasms ; genetics ; metabolism ; DNA, Complementary ; Floxuridine ; pharmacology ; Fluorouracil ; Genetic Vectors ; HT29 Cells ; Humans ; RNA, Messenger ; Thymidine Phosphorylase ; genetics ; metabolism ; Transfection

Objective To explore the feasibility and evaluate the teaching effect of case-based multidisciplinary team teaching mode in clinical practice teaching of gynecology.Method According to different grade,120 students were divided into experimental group and control group (60 students per group).The teaching content contained three malignant tumor cases,which were cervical cancer,endometrial cancer and ovarian cancer.The course needed 12 periods totally.The experimental group received multidisciplinary team (MDT) teaching mode,and the control group received traditional lecture-based learning teaching mode (LBL).Teaching effect evaluation and test scores would be analyzed at the end of teaching.SPSS19.0 was used for t test and chi-square test.Results Our results showed that the theory test scores,practical skills test scores,the paperwork scores and the total scores of the students in MDT group were significantly higher than those in the traditional group (P＜0.05).At the same time,the students' self-evaluation scores in the ability of information retrieval,acquisition,understanding,comprehensive and the ability of self-learning,learning interest,enthusiasm and teamwork were significantly higher than the traditional group (P＜0.05).Conclusion MDT teaching mode is feasible,which can improve teaching effect and students' quality,and is worthy of advocating and popularization.

Objective:To construct an entrustable professional activities (EPAs) assessment framework for undergraduate medical students suited to the national conditions in China.Methods:The Delphi method was used to construct an EPAs assessment framework for medical undergraduates. Twenty-one clinical experts across China were invited to participate in two rounds of Delphi consultation.Results:All the 21 experts completed the two rounds of Delphi consultation. The effective questionnaire response rates of the two rounds of consultation were 100.0% (21/21). For the first-round expert consultation, the W values of importance and feasibility scores of EPAs were 0.182 and 0.173 (both P<0.05), respectively. For the second-round expert consultation, the W values of importance and feasibility scores of EPAs were 0.167 and 0.152 (both P<0.05), respectively. According to the second-round Delphi consultation, the importance and feasibility scores of all 14 EPAs indicators were >3.5 points, with the coefficients of variation <0.25 points. We preliminarily established 12 EPAs indicators and 42 key assessment points and determined the expected entrustment levels of each EPA at different stages for medical undergraduates. Conclusion:This study preliminarily constructed an EPAs assessment framework for medical undergraduates, which provides a new evaluation method for the cultivation of medical undergraduates in China.

Objective To investigate the effects of arsenic trioxide (As2O3) on oxidative stress and apoptosis of neuroblastoma cells (SH-SY5Y) and the protective effect of folic acid (FA).Methods SH-SY5Y cells were cultured in vitro,and were divided into six groups:control group,low arsenic group (2.5 μmol/L As2O3),medium arsenic group (5.0 μmol/L As2O3),high arsenic group (10.0 μmol/L As2O3),FA intervention group (10.0 μmol/L As2O3,0.3 mmol/L FA),and FA control group (0.3 mmol/L FA).Each group of cells was cultured for 24 h or 5 h.Cell chromatin agglutination was observed by fluorescence staining.The ultrastructure of cells was observed by transmission electron microscope.The changes of oxidative stress related indicators of glutathione (GSH),malondialdehyde (MDA),superoxide dismutase (SOD),and reactive oxygen species (ROS) were detected;caspase 3 activity was also detected.Results Under fluorescence microscope,as the dose of arsenic increased,the nucleus became increasingly highlighted and a small number of cells in the medium and high arsenic groups showed chromatin agglutination,and FA intervention reduced chromatin agglutination.Under transmission electron microscope,the mitochondria of low and medium arsenic groups were slightly swollen and the endoplasmic reticulum was expanded;while the mitochondria of high arsenic group were significantly swollen and the nuclear membrane was ruptured,and the apoptotic bodies were observed.Mitochondria were slightly swollen after FA intervention.There were statistically significant differences in GSH content,SOD activity,ROS level and caspase 3 activity between groups (F =14.905,6.120,12.714,36.657,P ＜ 0.05).GSH content and SOD activity in high arsenic group [0.104 ± 0.074,(12.673 ± 5.106) U/mg prot] were lower than those in control group [1.000 ± 0.000,(34.699 ±3.998) U/mg prot,P ＜ 0.05].GSH content in FA intervention group (0.411 ± 0.344) was higher than that in high arsenic group (P ＜ 0.05).The ROS level and caspase 3 activity in high arsenic group were higher than those in control group (P ＜ 0.05),and the ROS level and caspase 3 activity in FA intervention group were lower than those in high arsenic group (P ＜ 0.05).There was no significant difference in MDA content between groups (F =8.207,P ＜ 0.05).Conclusions Arsenic exposure can inhibit the activity of antioxidants,cause oxidative stress injury,and increase the activity of caspase 3,leading to cell apoptosis.FA plays an antagonistic role in arsenicinduced oxidative damage and apoptosis of nerve cells.