Medicine is a practical application subject,so medical students should conduct numerous clinical practice to improve operation skills and clinical diagnosis ability The ability of clinical practice is one of most important indicators to evaluate medical education quality.In recent years,medical students have been affected by many kinds of adverse factors,such as new doctor-patient relationship,the medical reform and employment pressure and so on.All these adverse factors will bring a great challenge to the dental clinical teaching.In the new medical situation we need urgently to solve the problems to guide students to improve clinical practice ability and cultivate qualified dental professionals

BACKGROUND:Our preliminary study found that the monocusp valves made of ultramicropore expanded
polytetrafluoroethylene (ePTFE) revealed no significant thrombus, calcification, or degradation 20 weeks after implanted into the descending aorta and the left pulmonary artery in sheep, which verified the good property of ePTFE. However, the surface of ePTFE in the left pulmonary artery was covered with obvious neointima.
OBJECTIVE: To assess the biocompatibility of phosphorylcholine-coated ePTFE.
METHODS:ePTFE surface was modified by phosphorylcholine derivative. Then the changes of surface shape, tensile stress at yield and elasticity modulus, water contact angle, and protein absorption capacity of ePTFE after surface modification were observed. (1) Hemolytic test: the leaching solution of phosphorylcholine-coated ePTFE, leaching solution of uncoated ePTFE, normal saline, and distiled water were added to the diluted human blood, respectively. (2) Platelet count test: the phosphorylcholine-coated ePTFE, uncoated ePTFE, high density
polyethylene, and Zymosan A were added to the whole blood samples from healthy volunteers, respectively.
(3) Platelet activation test: the phosphorylcholine-coated ePTFE, uncoated ePTFE, γ-Globulins, and Zymosan A
were added to the whole blood samples from healthy volunteers, respectively.
RESULTS AND CONCLUSION: The mean micropore diameter of ePTFE was significantly decreased after
phosphorylcholine coating (P < 0.001). The hydrophilicity and the ability of suppressing protein adsorption were
significantly strengthened after phosphorylcholine coating (P < 0.001). Phosphorylcholine coating did not influence
ePTFE in biomechanical properties and hemolytic test. The platelet count test and platelet activation test demonstrated that phosphorylcholine coating significantly improved anti-thrombus function of ePTFE. So, phosphorylcholine coating can enhance anti-thrombus function, suppress protein adsorption, and improve biocompatibility of ePTFE.

Objective To explore and conclude the influence factors of long-term outcomes of mitral valve repair for moderate and severe mitral regurgitation due to myxomatous degeneration.Methods To review the in-patient data and followup outcomes of 261 patients after mitral valve repair for moderate and severe mitral regurgitation due to myxomatous degeneration from Jan 1993 to Jan 2008 in Changhai Hospital of Second Military Medical University.Results There were 7 perioperative deaths and 254 survivors who obtained satisfactory perioperative outcomes.During the follow-up,24 patients were lost and 230 patients were followed up from 36 months to 174 months (77.3 ±30.3) months and follow-up rate was 90.6％.Multivariate Cox regression shows age ≥ 60 years old,left ventricular ejection fraction ＜ 0.50,undergoing combined coronary artery bypass grafting were the independent risk factors for long-term death after operations and left ventricular ejection fraction ＜ 0.50,New York Heart Association functional classification Ⅲ-Ⅳ,anterior leaflet prolapse were the independent risk factors for long-term recurrent moderate or severe mitral regurgitation after operations and prosthetic ring or band annulopasty was a protective factor.Conclusion The age ≥60 years old,left ventricular ejection fraction ＜ 0.50,undergoing combined coronary artery bypass grafting,New York Heart Association functional classification Ⅲ - Ⅳ,anterior leaflet prolapse,and prosthetic ring or band annulopasty were closely related with long-term adverse events after operations.

Objective To summary the methods and results of first and second operations on patients with aortic valve disease and non-specific aortitis.Methods The total 34 patients including 23 cases with aortitis and 11 cases with Behcet disease were studied from Jan 2000 to Dec 2010.The first operation was Bentall procedure in 18 cases and AVR in 16 cases.Fourteen of 16 cases who had AVR developed severe paravalvular leakage,and undewent the second operation including 10 aortic root replacement (8 valve-conduit and 2 homograft) and 4 non-anatomic AVR.Results Eighteen patients who had first operation of Bentall procedure all survive without aortic pseudoaneurysm after the follow-up of 6 months to 11 years.Fourteen redo cases all survive except for one case died of repture of aortic pseudoaneurysm 1.2 years postoperatively.Conclusion Preoperative diagnosis in these patients is very difficulty.The first operation of root replacement is of choice.The second operation is very difficulty to handle,root replacement can achieve satisfactory results.Non-anatomic AVR is easy to perform,and good hemo stasis intraoperatively,and is a satisfied alternative method with good results.

This study aims to evaluate the accuracy of portable hemoglobinometer (Hemocue Hb 201+ hemoglobin analyzer) in patients with maintenance hemodialysis (MHD) and its diagnostic value for anemia. The data of venous hemoglobulin (Hb) and fingertip capillary hemoglobulin (DHb) in MHD patients from Lingnan Hospital, the Third Affiliated Hospital of Sun Yat-sen University were retrospectively analyzed, and the correlation and difference between DHb and Hb and the accuracy of DHb in the diagnosis of anemia were evaluated. A total of 105 patients were included in the study. There was no significant difference between the paired DHb and Hb [(109±21) g/L vs. (108±20) g/L, t=-1.284, P=0.202]. Pearson correlation analysis showed that DHb was positively correlated with Hb ( r=0.929, P<0.001). Linear regression analysis showed that DHb and Hb met the regression equation Hb=0.88×DHb+12.23, and P<0.001. Bland-Altman analysis showed that the differences between the paired DHb and Hb was (1.0±7.8) g/L with the limit of agreement as (-14.2, 16.2) g/L. The mean percentage of the differences in Hb was 1% with limit of agreement as (-13.7%, 15.7%). A DHb of >110 g/L was 0.90 sensitive and 0.83 specific to identify patients with an Hb >110 g/L and its positive and negative predictive values were 0.84 and 0.90, respectively. It suggests that, in MHD patients, Hemocue Hb 201+ analyzer shows good accuracy, and can be used to monitor the Hb trend and serve as a screen method for those reaching target Hb.

Objective    To analyze the etiologies, operation techniques and outcomes of redo aortic root replacement after cardiac surgery. Methods    Between December 2013 and December 2019, 30 patients who had at least one previous cardiac operation received aortic root replacement in our hospital, including 20 males and 10 females with an average age of 50.4±12.7 years. The mean time interval between this operation and the previous one was 8.0±8.5 years. The principal indication for surgery was aortic sinus dilatation and ascending aortic aneurysm in 14 patients (47%), acute aortic dissection in 5 patients (17%), pseudoaneurysm in 3 patients (10%), prosthetic valve endocarditis in 4 patients (13%), prosthetic leakage in 4 patients (13%). Bentall procedure was used in all 30 patients, with concomitant mitral valve plasticity or replacement in 5 patients, tricuspid valve plasticity in 6 patients, coronary artery bypass grafting in 3 patients, and total aortic arch replacement and elephant trunk procedure in 2 patients. Results    The mean cardiopulmonary bypass time was 96-296 (161.3±43.0) min, and the mean aortic occlusion time was 48-117 (85.7±20.4) min. There were 5 in-hospital deaths with an overall in-hospital mortality of 17%. The causes of deaths were low cardiac output syndrome in 2 patients and septic shock in 3 patients. The follow-up time was 3-75 (33.5±21.1) months. Three patients died during the follow-up, 1 patient died of septic shock and 2 died of cerebral hemorrhage. Conclusion    Redo aortic root replacement is difficult to deal with, and the risk is high. Preoperative evaluation is required, appropriate surgical approach, adequate myocardial protection, and a complete surgical plan are essential to ensure the success of the operation.