Research on the correlation between the preference of personalized learning resource recommendation system and self-directed learning level of medical students / 中华医学教育探索杂志

Objective:To understand the preferences of medical students for the performance, function and recommendation method of personalized learning resource recommendation system, as well as the correlation with the self-directed learning ability of medical students, so as to provide a reference for further building an effective learning platform and learning resource tool.Methods:A total of 482 first-year to third-year medical students in a medical university were selected as the research subjects. The electronic self-directed learning scale and the self-designed medical education learning resources recommendation system of performance, function and recommendation method scale were used to conduct a questionnaire survey. Pearson correlation analysis was used to explore the correlation between the performance, function and recommendation method preference of medical students' information resource recommendation system and self-directed learning ability.Results:Medical students had high demand and preference for learning [(4.35±0.58) points], accuracy [(4.32±0.62) points] and timeliness [(4.32±0.62) points] of learning resource recommendation system. In terms of the function of the recommendation system, the following [(4.10±0.71) points] and sharing [(3.94±0.82) points], and searching [(4.35±0.59) points], feedback [(4.09±0.73) points] and publication [(3.80±0.88) points] in the interactive function were all highly rated. For the preference of recommendation methods, the scores of discipline connection [(4.07±0.66) points] and time line [(4.02±0.74) points] were higher. The dimensions with high relevance to self-directed learning included timeliness ( r=0.367), social attributes ( r=0.361), and the basis of similar groups ( r=0.316). Conclusion:Medical students are familiar with and have a positive attitude towards the performance, functions and recommendation methods of the learning resource recommendation system, and have a cognitive foundation for the construction of the learning resource recommendation system and related resource platforms. This system has a certain correlation with the self-directed learning ability of medical students. Promoting the construction of medical education information resources is conducive to promoting the development of self-directed learning ability of medical students.

Finite Element Analysis and in vitro Hemodynamic Testing of Polyester Textile Valves with Nitinol Wires / 医用生物力学

Objective To study mechanical properties of polyethylene terephthalate (PET)-based textile valves woven with nickel-titanium (NiTi) wires by finite element method, and combined with in vitro hemodynamic testing, to analyze the effect of wire quantity and woven position on hemodynamic performance of PET textile valve. Methods The three-dimensional (3D) geometric models of PET valves without wires and models of PET valves with wires by different numbers and distributions in radial direction were constructed using modeling software. Material properties of PET valves and wires were given based on the literature and experimental data. The transvalvular pressure difference curves of PET valves obtained from in vitro pulsatile flow experiments were used as boundary conditions. Stress distributions of the valve during peak systole and diastole were studied by finite element analysis software. Hydrodynamic performance of the valve with wires was evaluated by in vitro pulsatile flow experiments. ResultsThe finite element analysis results showed that the radially woven NiTi wires could enhance support for the PET textile valve, and support force and area of the valve in belly region of the valve leaflet with evenly distributed metal wires increased with the number of metal wires. The situation of support force was similar for silk distributions on both sides of the belly. The weaving of wires reduced stress concentration on the PET textile valve to a certain extent. The pulsatile flow experiment results showed that the stability of opening and closing shapes, effective opening area (EOA), regurgitation fraction (RF) and transvalvular pressure differences for two kinds of the PET valves with woven wires were better than those of the PET valves without wires. Conclusions Weaving metal wires in radial direction of the PET textile valve can effectively reduce stress concentrations on the PET textile valve during the cardiac cycle, and reduce tearing possibility of the valve leaflet. The woven metal wires can improve opening and closing stability of PET textile valve in in vitro hydrodynamic test, increase EOA and reduce RF and transvalvular pressure difference of the PET valve.

Long non-coding RNA SAP30-2:1 is downregulated in congenital heart disease and regulates cell proliferation by targeting HAND2 / 医学前沿

Congenital heart disease (CHD) is the most common birth defect worldwide. Long non-coding RNAs (lncRNAs) have been implicated in many diseases. However, their involvement in CHD is not well understood. This study aimed to investigate the role of dysregulated lncRNAs in CHD. We used Gene Expression Omnibus data mining, bioinformatics analysis, and analysis of clinical tissue samples and observed that the novel lncRNA SAP30-2:1 with unknown function was significantly downregulated in damaged cardiac tissues from patients with CHD. Knockdown of lncRNA SAP30-2:1 inhibited the proliferation of human embryonic kidney and AC16 cells and decreased the expression of heart and neural crest derivatives expressed 2 (HAND2). Moreover, lncRNA SAP30-2:1 was associated with HAND2 by RNA immunoprecipitation. Overall, these results suggest that lncRNA SAP30-2:1 may be involved in heart development through affecting cell proliferation via targeting HAND2 and may thus represent a novel therapeutic target for CHD.

Enhanced production of bacitracin via energy metabolism engineering in Bacillus licheniformis DW2 / 生物工程学报

Bacitracin is a broad-spectrum cyclic peptide antibiotic, and mainly produced by Bacillus. Energy metabolism plays as a critical role in high-level production of target metabolites. In this study, Bacillus licheniformis DW2, an industrial strain for bacitracin production, was served as the original strain. First, our results confirmed that elimination of cytochrome bd oxidase branch via deleting gene cydB benefited bacitracin synthesis. Bacitracin titer and ATP content were increased by 10.97% and 22.96%, compared with those of original strain, respectively. Then, strengthening cytochrome aa3 oxidase branch via overexpressing gene qoxA was conducive to bacitracin production. Bacitracin titer and ATP content were increased by 18.97% and 34.00%, respectively. In addition, strengthening ADP synthesis supply is also proven as an effective strategy to promote intracellular ATP accumulation, overexpression of adenosine kinase DcK and adenylate kinase AdK could all improve bacitracin titers, among which, dck overexpression strain showed the better performance, and bacitracin titer was increased by 16.78%. Based on the above individual methods, a method of combining the deletion of gene cydB and overexpression of genes qoxA, dck were used to enhance ATP content of cells to 39.54 nmol/L, increased by 49.32% compared to original strain, and bacitracin titer produced by the final strain DW2-CQD (DW2ΔcydB::qoxA::dck) was 954.25 U/mL, increased by 21.66%. The bacitracin titer produced per cell was 2.11 U/CFU, increased by 11.05%. Collectively, this study demonstrates that improving ATP content was an efficient strategy to improve bacitracin production, and a promising strain B. licheniformis DW2-CQD was attained for industrial production of bacitracin.

Balloon occlusion technique combined with total arch replacement and frozen elephant trunk in the treatment of complex aortic arch diseases: an early clinical analysis of 100 cases in a single center / 中华胸心血管外科杂志

Objective:To evaluate the safety and efficacy of balloon occlusion technique combined with total arch replacement and frozen elephant trunk in the treatment of complex aortic arch diseases.Methods:The clinical data of 100 patients undergoing balloon occlusion technique combined with total arch replacement and frozen elephant trunk surgery in Fuwai Hospital from August 2017 to September 2018 were retrospectively reviewed, and the early clinical results were analyzed.Results:The average circulatory arrest time was(5.2±3.1) min. The lowest nasopharyngeal and bladder temperature was(27.9±1.0) ℃ and(29.2±1.2) ℃, respectively. One patient died in hospital due to multiple organ failure caused by acute liver failure, and a total of 4 patients died within 30 days. Other postoperative complications included cerebral infarction in 3 cases, paraplegia in 2 cases, low cardiac output syndrome requiring IABP assistance in 1 case, renal failure requiring continuous dialysis in 5 cases, redo for bleeding in 4 cases, reintubation in 3 cases, recurrent laryngeal nerve injury in 1 case, and osteofascial compartment syndrome in 1 case.Conclusion:Balloon occlusion technique combined with total arch replacement and frozen elephant trunk is safe and feasible in the treatment of complex aortic arch diseases. Its organ protection effect still needs to be confirmed by large sample comparison study.

Enhanced dissolution and oral bioavailability of baicalein by cocrystallization / 中国药科大学学报

@#Baicalein(BE), a natural flavonoid mainly extracted from Radix Scutellaria, has comprehensive pharmacological actions such as anti-inflammation, anti-virus and anti-cancer activities. It belongs to BCS class II compound with relatively low oral bioavailability. The current study aims to improve its aqueous solubility and dissolution and hence to enhance its oral absorption by cocrystallization technique. Slurry crystallization method was employed to prepare baicalein cocrystal with co-former caffeine(CA), followed by physicochemical characterizations with DSC, XRPD and FTIR. Compared to BE and physical mixture of BE and CA, BE-CA cocrystal had a significantly higher dissolution of BE. In addition, in comparison to BE, this cocrystal achieved reduced time to peak(tmax)as well as significantly higher peak plasma concentrations(cmax)and area under the curve(AUCs)for both BE and its active metabolite baicalin(BI)in rats, suggesting enhanced the oral bioavailability of BE.

Effect analysis of combined treatment with multiple drugs on upper gastrointestinal bleeding in emergency internal medicine / 中国生化药物杂志

Objective To investigate the clinical effect of combined treatment of upper gastrointestinal bleeding in emergency internal medicine. Methods A total of 102 patients with upper gastrointestinal bleeding were enrolled in the Department of Emergency Gastroenterology, Peking Binhai University Hospital from June 2014 to October 2016. The patients were randomly divided into observation group and control group, 51 cases in each group.The control group were only given omeprazole sodium, tranexamic acid injection,the observation group were given Agkistrodon hemocoagulase for injection on patients on the basis of the control group.After treatment, the clinical curative effect of two groups of patients were evaluated, the hospitalization days, the average hemostasis time, blood transfusion, bowel recovery time, abdominal pain relief time, the adverse reactions occurred of the two groups were observed.Results The total effective rate of the observation group was significantly higher than that of the control group (P< 0.05). The hemostasis time,the time of hospitalization and the average blood transfusion in the observation group were significantly lower than those in the control group (P<0.05). The recovery time of bowel and the time of pain relief in the observation group were significantly lower than in the control group (P<0.05). There was no significant difference in the incidence of adverse reactions between the observation group and the control group.Conclusion Comprehensive treatment of upper gastrointestinal bleeding with emergency internal medicine can significantly improve the clinical efficacy, shorten the time of hemostasis and recovery, and is worthy of clinical application.

Development of transcriptional regulators of Streptococcus mutans in cariogenic virulence / 华西口腔医学杂志

Some transcriptional regulators contribute to the expression of Streptococcus mutans (S. mutans) cariogenic virulence factors. Although the target sequence transcriptional regulators anchored on the cell wall and the molecular mechanism of the regulation of S. mutans are yet to be clarified, certain global regulators potentially associated with the cariogenicity of S. mutans have been identified. This review is about these related transcriptional regulators, their function, and possible mechanisms.

Research progress on gene involved in tooth agenesis / 华西口腔医学杂志

Tooth agenesis, belonging to the abnormal tooth development, is a common disease in clinic. The disease not only affects the person's chewing function, but also influences the pronunciation, appearance and mental health. In the past, genetic linkage and molecular biology research have made clear of part of the genetic mutations' sites of the syndromic and non-syndromic tooth agenesis. Although the mechanism was not clear yet, but the important mutations are now known to be involved in many factors. Thesyndromic and non-syndromic tooth agenesis related gene are reviewed in this paper.