Objective:To investigate the application effect of case-based learning (CBL) in clinical practice teaching of cardiothoracic surgery.Methods:A total of 86 interns who rotated in our department from February to November 2019 were randomized into observation group ( n = 43) and control group ( n = 43) by drawing lots. The control group used traditional teaching method, and the observation group used CBL teaching method. The differences between the two groups in professional theoretical performance, clinical skill achievement and teaching satisfaction were compared. Results:The professional theoretical scores, clinical skills scores, and teaching satisfaction of the observation group were better than those of the control group, with statistical differences ( P < 0.05). Conclusion:The CBL teaching method can effectively help interns master professional theoretical knowledge and clinical practice skills of cardiothoracic surgery, which has obtained satisfactory teaching results and is worthy of promotion.

@@

Pig copper zinc superoxide dismutase (CuZnSOD) is an important antioxidant enzyme. Some studies focused on the function of CuZnSOD gene, but the transcriptional regulation of the CuZnSOD gene is not yet fully elucidated. Therefore, the aims of the study were to determine the core promoter region and to explore its mechanism of transcriptional regulation. The 853 bp DNA sequence of 5'-flanking promoter was amplified by performing PCR. A series of CuZnSOD promoter fragments with gradually truncated 5'-end were produced by nested PCR and inserted into pGL3-Basic vector. The activities of the promoters were measured by the dual-luciferase assay system after transient transfection into the NIH/3T3 cells. The results demonstrated that there were 2 potential transcription start sites in the regions from initiation codon to -87 bp and -266 bp, respectively. The region from -383 bp to +67 bp in CuZnSOD gene promoter showed higher activity than other regions, and further deletion analysis demonstrated that the region from -75 bp to -32 bp contained an essential promoter sequence for pig CuZnSOD gene transcription. In addition, several potential transcription factor binding sites were predicted with bioinformatics method. These results suggest that these transcription factor binding sites may be involved in the transcriptional regulation of CuZnSOD gene.
Animals ; Cloning, Molecular ; Gene Expression Regulation ; Genetic Vectors ; Mice ; NIH 3T3 Cells ; Promoter Regions, Genetic ; Superoxide Dismutase ; genetics ; Swine ; Transfection

Objective The aim of this study was to investigate the relationship between phosphotyrosine interac-tion domain containing 1 ( PID1 ) gene and variation in intramuscular fat ( IMF ) content and the possibility to generate transgenic animals by testicular injection .Methods Expression vector pIRES2-acGFP-PID1 carrying pig PID1 gene was incubated with transfection reagents and injected into the testes of male New Zealand rabbits .We examined the F1 genera-tion by fluorescence detection , PCR, Western blotting and measuring the IMF content .The F1 generation gave birth to the F2 generation.Then we examined the F2 generation through detecting the positive rate and the IMF content .Results The exogenous PID1 gene and fluorescent protein gene were expressed at different levels both in the F 1 generation and the F2 generation, and the positive rates were 35.88%and 34.33%, respectively.The IMF content was significantly elevated (P<0.05) in the transgenic positive individuals compared with the negative ones and the control group , and the PID1 protein expression was similarly higher .Conclusions The results of this study demonstrate that PID 1 gene affects intramuscular fat content significantly .Moreover, the results of our analysis provide further evidence that transgenic animals can be gener -ated by testicular injection , and the exogenous gene can be inherited steadily .

BACKGROUNDWith the development of patch clamp and molecular biology technique, and the application of them in the investigation of tumor cellular membrane ion channnel, the ion channel is becoming the hot spot of the tumor base research gradually. The aim of this study is to investigate the electrophysiological properties of human lung adenocarcinoma cell line A-549 and the role of K+ channel in inhibition of cell proliferation by the recombinant mutant human tumor necrosis factor (rmhTNF).

METHODSIonic currents were recorded using the whole-cell patch clamp recording technique. The proliferation activity of A-549 cells was measured by MTT assay. The cell cycle and apoptosis rates of the carcinoma cells were measured by flow cytometric analysis (FCM).

RESULTSWhole-cell patch clamp recording revealed a voltage-gated K+ current in A-549 cells, which could be blocked by the K+ channel blocker, TEA and CsCl. The amplitude of K+ current was markedly diminished in all cells incubated with different concentration of rmhTNF (P < 0.01). Obvious inhibitive effect of rmhTNF on proliferation of the cells was found in vitro in a dose-dependent manner (P < 0.01), the maximal inhibitory rate was 38.68% when the concentration was 400U/mL. The rmhTNF inhibited the cell cycle shifting from G1 phase to S phase and promoted apoptosis as determined by FCM analysis. The proportion of G1 cells increased from 53.02% to 72.93%, and the apoptosis rate increased from 2.08% to 8.68%. The difference were significant between the control and the high concentration groups ( 200U/mL and 400U/mL) (P < 0.01).

CONCLUSIONSrmhTNF exerts its cytotoxic effects on A-549 cells through inhibiting cell cycle shifting and inducing apoptosis. The K+ channels on the A-549 cell membrane can be blocked by rmhTNF partly, and the effect of inhibiting proliferation and activating apoptosis on A-549 cells is a result of depression of the K+ channel.

BACKGROUNDOncogenesis, development, invasion and metastasis of lung cancer are modulated by relative genes of lung cancer, and the expression, deletion or mutation of these genes are regulated by cell membrane signal transduction system and cell membrane ionic channels. The aim of this study is to explore the electrophysiological properties of human lung adenocarcinoma cell line A549 and cell proliferation affected by tetraethylammonium chloride (TEA), one potassium channel blocker, so as to know whether the voltage-gated potassium channels are required for the proliferation of A549 cell line.

METHODSIonic currents were recorded by whole-cell patch-clamp recording technique. The proliferation activity of A549 cells was measured by MTT assay.

RESULTSMembrane current was observed when cells were held at -70mV and test potentials ranged from -30 to +110mV. The current exhibited properties of voltage-dependent, outward rectification and no or little inactivation over the 500ms voltage pulse. Exposure of tumor cells to 10mmol/L TEA reduced the peak outward potassium current (evoked by depolarization to +110mV) from (1057.52±59.17)pA to (212.26±11.96)pA, the ratio of suppression was 79.92% (P < 0.01). Obvious inhibitive effect of TEA with different concentrations ranged from 20 to 60mmol/L on proliferation activity of the cells was found.

CONCLUSIONSThe voltage-gated potassium channels exist in human lung adenocarcinoma cell line A549 and play a great role in proliferation of A549 cells. TEA can inhibit proliferation of A549 cell through blocking the potassium channels and the inhibition is dose-dependent.