BACKGROUND: Magnitude and action ways of flow shear stress are important for the endothelialization of small diameter tissue-engineered vessels (TEV), and the TEV resistance ability to blood flow even decides the destiny of implantation. There are many studies on how to construct the TEV and improve anticoagulant ability of TEV after host cell implantation, but the effects of different flow shear stresses on the TEV endothelialization is rarely reported, which may be helpful for increasing the success rate of TEV implantation. OBJECTIVE: To compare the effects of flow shear stresses in single level or stepwise increased on the endothelialization of small diameter TEV and to optimize the TEV in the aspects of shear stress magnitude and loading method. METHODS: The number, morphology and adhesion ability of endothelial cells on the inner wall of TEV were observed through silver nitrate and F-actin staining. RESULTS AND CONCLUSION: Single-level shear stress at 2.5, 3.0 N/m2 for 2 hours removed almost all the endothelial cells seeded on the inner wall of TEV. In contrast, stepwise increased shear stress from 0.5 N/m2 to 3.0 N/m2 at an increase of 0.2 N/m2/2 hours maintained the integrity and oriented along the flow direction, and could induce stress fibers productionin endothelial cells. These results suggest that the stepwise increased flow shear stress can improve the endothelialization of TEV.

Objective To study clinical manifestations, risk factors and prognosis of patients with systemic lupus erythematosus (SLE) complicated with digital gangrene. Methods Data of 2684 inpatients with SLE admired to Peking Union Medical College Hospital during December 1997 to August 2007, including demographic information, clinical features, laboratory findings, as well as therapeutic regimens, were retrospectively analyzed, and 18 of those complicated with digital gangrene were identified and followed up. Results Average age at onset in patients of SLE complicated with digital gangrene was(33±12)years, with an average duration of disease course of (99±60 ) months.Longer course duration ( ≥ 4 yrs), Raynaud's phenomenon, elevated serum C-reactive protein (CRP) and positive anti-SSA antibody all were associated with occurrence of digital gangrene in patients of SLE, with P values of 0.012, 0.004, 0.037 and 0.087 respectively, and odds ratios of 1.03 (95% CI 1.01～1.05 ), 39.05 (95% CI 3.31～460.13 ), 17.99 (95%(CI 1.19～271.29) and 7.01 (95% CI 0.75～65.12), respectively. Fifteen of 18 SLE patients complicated with digital gangrene started treatment with predisone ≥1 mg˙kg-1 ˙d-1, and eighteen all were treated with cyclophosphamide, though eight cases failed and ultimately received digital amputation. Prompt corticosteroid treatment (predisone ≥ 1 mg˙kg-1˙d-1 within three weeks after occurrence) could decrease risk for amputation, with P =0.081 and OR =0.135 (95% CI 0.01～1.28). Conclusions Longer duration of disease course, Raynaud's phenomenon, elevated serum CRP and positive anti-SSA antibody all are independent predictors of SLE complicated with digital gangrene. Early and aggressive treatment can prevent occurrence of gangrene from its progression and improve its prognosis.

Objective: To investigate the prevalence of dyslipidemia among adult professional athletes in Guangdong Province, so as to provide insights into dyslipidemia screening and health management among professional athletes. Methods: In 2019, active athletes at ages of 18 to 30 years were recruited from 12 provincial sports teams in Guangdong Province using a cluster sampling method. A self-designed questionnaire survey was conducted to collect gender, age and sport items, and the levels of triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) were detected. The non-HDL-C level was calculated, and the gender- and sport item-specific prevalence of dyslipidemia was estimated. Results: Totally 460 athletes were investigated, including 245 males (53.26%) and 215 females (46.74%), with a mean age of (21.91±2.77) years. The overall detection of dyslipidemia was 25.87%, and the detection rates of high TG, high TC, high LDL-C, low-HDL-C and high non-HDL-C were 20.22%, 5.87%, 13.04%, 3.26% and 9.57%, respectively. The detection rates of high TG (9.39% vs. 1.86%; χ2=11.743, P<0.05), low HDL-C (5.31% vs. 0.93%; χ2=6.951, P<0.05) and high non-HDL-C (12.24% vs. 6.51%; χ2=4.351, P<0.05) were significantly greater in men than in women, and the detection of high TC was lower in men than in women (17.96% vs. 22.79%; χ2=8.627, P<0.05). There was a significant difference in the detection of dyslipidemia among athletes engaging in different sport items (χ2=47.552, P<0.05), and a high detection rate of dyslipidemia was seen in baseball athletes (34.29%), softball athletes (37.04%), shooting/archery athletes (52.73%). Conclusion The prevalence of dyslipidemia was 25.87% among adult professional athletes in Guangdong Province, and high TC in combination with high LDL-C were the predominant type of dyslipidemia. The management of blood lipids should be given a high priority to male athletes and baseball, softball and shooting/archery athletes.

Objective To investigate how build a comprehensive basic theory training curriculum for residents.Methods Random questionnaire survey of residents,along with a forum of experts to explore an optimal basic theory training curriculum for residents.Results 71.9％ of the residents surveyed were satisfied with the basic theory training curriculum,14.9％ proposing training time be adjusted to evenings or weekends,and 8.8％ proposing to adjust the training content.Conclusion A diversified reform on the training content,training time,training teachers,management and teaching evaluation aspects.These will help building a comprehensive and practical,standardized and reasonable basic theory curriculum,in order to effectively improve the quality of residency training.

In the era of digital information,internet plus mode provides new opportunities for the development of traditional medical education.This paper introduces the application patterns of internet plus mode in the medical education,including the following aspects,such as the construction of medical quality resources sharing class,the implementing of medical massive open online courses and other kinds of open online courses,making comprehensive construction of textbooks,using social interactive software and some new wearable devices such as Google glass,distance education and so on.And from the construction of autonomy,sharing,dynamic teaching atmosphere and building a new relationship between teachers and students,it explores the application advantage of Internet plus in medical education,emphasizes thatInternet plus mode and traditional medical education should be organically integrated and financed.At the same time,we should improve the evaluation of information quality,study the integrity test,and the application of big data processing,so as to provide some ideas for the sustainable development.

Objective To compare cellular immune responses in mice elicited by Chinese different AIDS candidate vaccines.Methods According to their different immunization procedures,BALB/c mice were immunized with 6 AIDS candidate vaccines,separately.Spleen cells were isolated for the detection of cellular immune response to HIV-specific peptides using enzyme-linked immunosorbent spot(ELISPOT)assay and intracellular cytokine staining(ICS)method.Results AIDS vaccines were evaluated by using potential T-cell epitopes(PTE)Gag,Env and Pol peptides pool and ELISPOT.The positive conversion rates for cellular immune response of 1#-6# vaccines fluctuated from 70% to 100%.The vaccine-induced cellular immune responses to specific peptides pool are different not only in magnitude but also in breadth.The Th1type cytokines,IFN-γand IL-2,were detected with ELISPOT in 1# and 2# vaccines.The productions of IFN-γand IL-2 induced by both of the two vaccines showed a moderate correlation(r1 =0.62,P1 ＜0.01 ;r2=0.79,P2 ＜ 0.01).The positive conversion rate of IFN-γ secreting cells of 1 # vaccine was 66.7%(10/15)mice detected with both ELISPOT and ICS.And the results tested by ELISPOT and ICS showed moderate correlation(r = 0.55,P ＜ 0.05).Conclusion The magnitude and breadth of cellular immune responses induced by different AIDS candidate vaccines are different.Being induced by different AIDS candidate vaccines,the IFN-γand other Th1 type cytokines detected by ELISPOT or ICS could be used to evaluate the cellular immune responses in mice.

Chitosan is a polymer with good biocompatibility, unique pH-responsive solubility, convenient modification and easier film-formability. Chitosan could serve as an active mediator between biological components and microfabricated devices to prepare biological micro electro mechanical systems (BioMEMS) with high selectivity and sensitivity. Recently, there has been a growing interest in BioMEMS based on biofabrication of chitosan. We reviewed the mechanisms and processes of three biofabrication methods based on chitosan, including directed assembly, enzymatic assembly and self-assembly. Current applications and research progress in biological, medical and environmental fields are also discussed. Finally, future research directions are prospected.
Biocompatible Materials ; chemistry ; Biomimetics ; Biosensing Techniques ; Catalysis ; Chitosan ; chemistry ; Micro-Electrical-Mechanical Systems ; methods ; Nanotechnology ; Nucleic Acid Hybridization

Objective To analyze the practicability of using ELISA kit for the detection of hepati-tis E virus antigen ( HEV-Ag) in plasma donations and Biomex HEV seroconversion panels. Methods The HEV-Ag positive samples were screened out from 36 340 donated blood plasma samples. Real-time fluores-cent PCR was performed for the detection of HEV RNA in HEV-Ag positive samples. The open reading frame 2 (ORF2) in HEV RNA was amplified by nested RT-PCR and the amplified products were confirmed by sequencing analysis. Phylogenetic tree was constructed for HEV genotyping. Five Biomex HEV serocon-version panels were used in this study for the detection of HEV-Ag, anti-HEV antibody and HEV RNA as well as the correlation analysis between HEV-Ag and HEV RNA. Results Twenty-six out of 36 340 plasma samples (0. 07%) were positive for HEV-Ag. Of the 26 samples, 25 samples were positive for HEV RNA as indicated by the results of nested RT-PCR and 23 positive samples were confirmed by sequencing analysis. The positive rate of HEV RNA in blood plasma donators was 1 ∶ 1 580 (0. 06%). There were 17 samples of genotype 1 (74%) and 6 samples of genotype 4 (26%) according to the phylogenetic tree analysis. All of the HEV-Ag positive samples were also positive for HEV RNA as indicated by the analysis of Biomex sero-conversion panels. HEV-Ag was consistent with the peak of the HEV RNA concentration. Conclusion A close relationship between HEV-Ag and HEV RNA was observed. HEV-Ag screening could be used as a measure to reduce the risk of HEV transmission by blood transfusion.

Objective:To realize the characteristics of postgraduate students applying for Peking University Third Hospital and to explore the strategies to improve the enrollment quality on the background of "Double first-class".Methods:Enrollment data from 2015 to 2019 of the Peking University Third Hospital was statistically analyzed by SPSS 17.0 software. For variables that did not conform to the normal distribution, median and quartile were utilized for description. Mann-Whitney U test was utilized for comparison between admission group and non-admission group. For the counting data, number of cases and proportion were utilized for description. The comparison between groups was performed by chi-square test or Fisher precision test. All tests were two-sided and had a significance level of 0.05. Results:The average enrollment ratio was 4.9∶1. The overall admission rate of first choice was 76.9% (450/585), which kept increased steadily, and the gap between national key clinical specialties and non-key specialties was narrowed. The geographical distribution of students was mainly in north China (30%, 175/585) and east China (28%, 164/585). The admission group had characteristics of high score of CET-6 (505 vs. 480, Z=-5.86, P<0.001) and young age (24 vs. 25, Z=-8.15, P<0.001). The proportion of "985", "211" or "Double first-class" universities, patents invention, conference speeches and high level awards in admission group was higher than that in non-admission group. Conclusion:Sustainable policies should be taken to constantly improve the quality of enrollment including establishing sound mechanism of discipline adjustment and optimization, increasing the publicity of enrollment nationwide, and strengthening the selection of the comprehensive ability of students centered on the construction of first-class disciplines.

The training of residents majoring in ultrasound needs not only to pay attention to the teaching of speculative knowledge,but also to "look at pictures and talk",which is based on a large number of diagnostic ultrasound cases,training the residents to find,discover and discriminate the lesions from the ultrasonic images to finally form a sharp recognition and diagnosis ability.This study used the instant messaging tool WeChat to establish a virtual learning platform and implement a case based teaching process through this platform,which can avoid the limitations of time and space,and make the communication between teachers and students faster.According to the questionnaire survey,residents generally believed that the training mode can effectively improve learning efficiency and professional ability and hope to add this training mode to the basis of traditional teaching mode.The results of resident case analysis showed that the diagnostic accuracy of residents gradually increased during the training process.The model of WeChat platform combined with case teaching can provide new ideas and methods for standardized training of resident doctors in ultrasound specialty.