Objective　To conduct a genotypic analysis of dengue virus in Gengma County, Yunnan Province, located in the China-Myanmar border region in 2023, and provide a reference for developing effective clinical diagnosis and treatment strategies for dengue fever in the region. Methods Serum samples were collected from hospitalized patients testing positive for dengue NS1 antigen, and dengue virus nucleic acid was detected using real-time quantitative PCR (qPCR). Nucleic acid-positive samples underwent cell culture and sequencing analysis of the dengue virus E gene to determine the origin of the virus. Results Specific nucleic acid detection was performed in 86 NS1-positive serum samples, 75 samples tested positive for dengue virus serotype 1 (DENV-1), 6 samples for serotype 2 (DENV-2), and 5 samples were DENV-negative. Twelve DENV-1 and four DENV-2 strains were obtained by blind cell culture transmission for 3 generations. Sequencing of E gene sequences (1 485 bp) of 16 strains showed that the nucleotide similarity of 12 DENV-1 E gene sequences ranged from 99.3% to 100.0%, with amino acid homology of 99.8% to 100.0%. For the 4 DENV-2 E gene sequences, the nucleotide similarity ranged from 99.7% to 99.9%, and amino acid homology ranged from 99.0% to 99.8%. Phylogenetic analysis showed that 12 DENV-1 strains belonged to genotype I, while 4 DENV-2 strains belonged to the Asian-II genotype. Conclusion The dengue fever outbreak in Gengma County, Yunnan Province, China, the China-Myanmar border area, was mainly caused by dengue virus 1 genotype I and dengue virus 2 genotype Asian-II. Both dengue virus 1 and 2 may have similar original strains from Guangzhou, China in 2023. It was recommended that local relative departments should strengthen the monitoring of dengue fever.

L-citrulline is a nonprotein amino acid that plays an important role in human health and has great market demand. Although microbial cell factories have been widely used for biosynthesis, there are still challenges such as genetic instability and low efficiency in the biosynthesis of L-citrulline. In this study, an efficient, plasmid-free, non-inducible L-citrulline-producing strain of Escherichia coli BL21(DE3) was engineered by combined strategies. Firstly, a chassis strain capable of synthesizing L-citrulline was constructed by block of L-citrulline degradation and removal of feedback inhibition, with the L-citrulline titer of 0.43 g/L. Secondly, a push-pull-restrain strategy was employed to enhance the L-citrulline biosynthesis, which realized the L-citrulline titer of 6.0 g/L. Thirdly, the NADPH synthesis and L-citrulline transport were strengthened to promote the synthesis efficiency, which achieved the L-citrulline titer of 11.6 g/L. Finally, fed-batch fermentation was performed with the engineered strain in a 3 L fermenter, in which the L-citrulline titer reached 44.9 g/L. This study lays the foundation for the industrial production of L-citrulline and provides insights for the modification of other amino acid metabolic networks.
Citrulline/biosynthesis* ; Escherichia coli/genetics* ; Metabolic Engineering/methods* ; Fermentation ; NADP/biosynthesis*

Objective:To investigate the impact of abnormal patterns of 75 g oral glucose tolerance test (OGTT) in the second trimester on the risk of large for gestational age (LGA) newborn deliveries.Methods:General clinical data and OGTT results of 66 290 pregnant women who received regular prenatal care and delivered in Guangdong Maternal and Child Health Hospital from December 24, 2016 to July 26, 2022 were collected. According to the results of OGTT, the pregnant women were divided into 8 groups: normal blood glucose group (normal fasting blood glucose, 1-hour and 2-hour after oral glucose, 54 518 cases), gestational diabetes mellitus (GDM) 0 group (only abnormal fasting blood glucose, 1 430 cases), GDM 1 group (only abnormal blood glucose at 1-hour after oral glucose, 2 150 cases), GDM 2 group (only abnormal blood glucose at 2-hour after oral glucose, 3 736 cases), GDM 0+1 group (both fasting blood glucose and 1-hour after oral glucose were abnormal, 371 cases), GDM 0+2 group (both fasting blood glucose and 2-hour after oral glucose were abnormal, 280 cases), GDM 1+2 group (abnormal blood glucose at 1-hour and 2-hour after oral glucose, 2 981 cases) and GDM 0+1+2 group (abnormal fasting blood glucose, 1-hour and 2-hour after oral glucose, 824 cases). Multivariate logistic regression was used to analyze the effects of different abnormal OGTT patterns on LGA. In addition, the blood glucose measurements at the three time points of OGTT were combined and used as continuous variables in the receiver operating characteristic (ROC) curve to evaluate the predictive value of each blood glucose measurement mode for LGA and the area under the curve (AUC) was compared.Results:(1) Multivariate logistic regression analysis showed that the risks of LGA were significantly increased in GDM 0 group ( OR=1.76, 95% CI: 1.50-2.08; P<0.001), GDM 0+1 group ( OR=2.29, 95% CI: 1.72-3.04; P<0.001), and GDM 0+1+2 group ( OR=1.98, 95% CI: 1.61-2.43; P<0.001). (2) ROC curve analysis showed that fasting blood glucose, 1-hour after oral glucose, 2-hour after oral glucose, fasting+1-hour after oral glucose, fasting+2-hour after oral glucose, 1-hour+2-hour after oral glucose, and fasting+1-hour+2-hour after oral glucose had certain predictive value for LGA (all P<0.001). The AUC of fasting blood glucose measurement was higher than that of 2-hour blood glucose measurement in predicting LGA, and the difference was statistically significant ( P<0.05). There was no significant difference in the AUC between fasting blood glucose and other blood glucose measurement modes for predicting LGA (all P>0.05). Conclusions:In the abnormal OGTT patterns, pregnant women with abnormal fasting blood glucose, abnormal fasting+1-hour after oral glucose, and abnormal fasting+1-hour+2-hour after oral glucose have an increased risk of LGA. Fasting blood glucose measurement is of great significance for the prediction of LGA, and could be used as an optimal indicator to evaluate the risk of LGA in clinical practice.

Objective:To explore the application and practice of "flipped classroom" in the teaching of general surgery interns.Methods:A total of 20 internship groups (3 to 5 people in each group) were randomly selected from the general surgery practice group in the Department of General Surgery of the Second Clinical Medical College of North Sichuan Medical College. They were randomly divided into the flipped group (45 people) and the traditional group (40 people), with 10 subgroups in each group. The flipped group adopted the flipped classroom teaching mode (students' self-study by handing out materials before class, students and teachers' discussion in class, and students and teachers' evaluation after class), while the control group adopted the current conventional teaching mode (students' preview before class, teachers' explanation in class, and teachers' question answering after class). At the end of the teaching, a questionnaire was used to evaluate the participation and completion of each student. The teaching effect was evaluated by medical history collection and case analysis. The participation, completion, and teaching effect between the two groups were compared and analyzed. SPSS 23.0 software was used for t-test and Chi-square test. Results:The participation of the flipped group was better than that of the traditional group [(17.45±1.83) vs. (15.57±1.52)], and the difference was statistically significant ( P < 0.05). There was no statistically significant difference between the flipped group and the traditional group. There was no significant difference in medical history collection scores between the two groups. The case analysis of the flipped group was better than that of the traditional group [(87.30±6.06) vs. (81.50±5.88), P < 0.05]. The questionnaire shows that about 90% of the students think that flipped classroom can improve their interest in learning [96% (43/45)], improve their autonomous learning ability [89% (40/45)], and have better learning effect. At the same time, 78% (35/45) of students think that learning time is too long. Conclusion:The flipped classroom teaching model can improve the teaching participation of general surgery students, improve students' interest in learning, improve their self-learning ability, and improve students' thinking ability of medical record analysis.

Diacylglycerol (DAG) is an intermediate product in lipid metabolism and plays an important physiological role in human body. It is mainly prepared by hydrolyzing lipid with lipase. However, research on the detection method of 1, 2-diacylglycerol (1, 2-DAG) and 1, 3-diacylglycerol (1, 3-DAG) and catalytic specificity of lipase was not enough, which limits its wide application. To address these challenges, an efficient quantitative detection method was first established for 1, 2-DAG (0.025-0.200 g/L) and 1, 3-DAG (0.025-0.150 g/L) by combining supercritical fluid chromatography with evaporative light scattering detector and optimizing the detection and analysis parameters. Based on the molecular docking between Thermomyces lanuginosus lipase (TLL) and triolein, five potential substrate binding sites were selected for site-specific saturation mutation to construct a mutation library for enzyme activity and position specificity screening. The specificity of sn-1, 3 of the I202V mutant was the highest in the library, which was 11.7% higher than the specificity of the wild type TLL. In summary, the position specificity of TLL was modified based on a semi-rational design, and an efficient separation and detection method of DAG isomers was also established, which provided a reference for the study of the catalytic specificity of lipase.
Humans ; Diglycerides ; Molecular Docking Simulation ; Binding Sites ; Catalysis ; Lipase/genetics*

Group A Streptococcus (GAS) is a very important pathogen, especially for children.On a global scale, GAS is an important cause of morbidity and mortality.But the burden of disease caused by GAS is still unknown in China and also has not obtained enough attention.For this purpose, the expert consensus is comprehensively described in diagnosis, treatment and prevention of GAS diseases in children, covering related aspects of pneumology, infectiology, immunology, microbiology, cardiology, nephrology, critical care medicine and preventive medicine.Accordingly, the consensus document was intended to improve management strategies of GAS disease in Chinese children.

Genome-scale metabolic network model (GSMM) is an extremely important guiding tool in the targeted modification of industrial microbial strains, which helps researchers to quickly obtain industrial microbes with specific traits and has attracted increasing attention. Here we reviewe the development history of GSMM and summarized the construction method of GSMM. Furthermore, the development and application of GSMM in industrial microorganisms are elaborated by using four typical industrial microorganisms (Bacillus subtilis, Escherichia coli, Corynebacterium glutamicum, and Saccharomyces cerevisiae) as examples. In addition, prospects in the development trend of GSMM are proposed.
Corynebacterium glutamicum/genetics* ; Escherichia coli/genetics* ; Metabolic Engineering ; Metabolic Networks and Pathways/genetics*

Objective:To explore the expressions of programmed death-1 (PD-1) and programmed death-ligand 1 (PD-L1) and clinicopathological characteristics in post-transplant lymphoproliferative disorder (PTLD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) in children, with the aim of clarifying whether checkpoint inhibition of PD-1/PD-L1 inhibitors may serve as a therapy option.Methods:The clinical data of 13 cases of PTLD after allo-HSCT pathologically confirmed in Shenzhen Children′s Hospital from January 1, 2012 to December 30, 2019 were retrospectively analyzed.The detection was performed by immunohistochemical staining by MaxVision? method, Epstein-Barr virus(EBV) in situ hybridization and lymphoma gene rearrangement.The relationship between the expression of PD-1 and PD-L1 and the clinicopathological characteristics of PTLD were analyzed.Results:The expression of PD-1 was not correlated with gender, age, primary diseases, histopathological types, transplantation mode and the expression of EBV in situ hybridization (all P>0.05). The expression of PD-L1 was correlated with histopathological types ( P<0.05). Furthermore, the expression rate of PD-L1 on severe β-thalassemia was significantly higher than that of severe aplastic anemia [90.0%(9/10 cases) vs. 66.7%(2/3 cases)] and monomorphic PTLD was higher than that of polymorphic PTLD [100.0%(2/2 cases) vs. 83.3%(5/6 cases)]. Moreover, the positive PTLD in EBV was higher than the negative PTLD in EBV [90.9%(10/11 cases) vs. 50.0%(1/2 cases)]. The positive rates of PD-1 and PD-L1 in 13 cases with PTLD were 46.2%(6/13 cases) and 61.5%(8/13 cases) in tumor cells, 92.3% (12/13 cases) and 76.9% (10/13 cases) in microenvironmental cells, and 84.6%(11/13 cases) in EBV, respectively. Conclusions:PD-L1 has a higher positive rate in tumor cells with monomorphic PTLD; and routine staining for PD-1 and PD-L1 can be performed in all types of PTLD when standard immunotherapy and chemotherapy are ineffective.

Objective:To summarized the experience of 149 cases of critical pediatric cardiac surgery in a single-center during the epidemic period, for providing a safe and feasible management strategy.Methods:Based on the epidemiological characteristics of COVID-19, a strategy consisting of 14 days of isolation was established for the arrangement of cardiac surgery in children during the epidemic period. Retrospective analysis of clinical data of 149 cases of critical cardiac surgery performed from January 23, 2020 to March 20, 2020 under the guidance of this strategy. The primary composite endpoint was death and suspected or confirmed COVID-19.Results:The median age of the children undergoing surgery was 136 days; 73(49.0%) cases were male. Twenty-one cases (14.1%) came from Shanghai, one case (0.7%) came from Hubei Province, and 127 cases (85.2%) came from areas other than Hubei and Shanghai. One patient (0.7%) outside Shanghai who had been isolated for less than 14 days carried emergency surgery under special protection; other 148 patients (99.3%) underwent elective early repair procedure. One patient (0.7%) died, and no COVID-19 was confirmed or suspected.Conclusion:During the COVID-19 epidemic, pediatric cardiac surgery can be safely performed using a specific management strategy, which can be used as a reference when major public health events occur.

With the advent of the post-genomic era, metabolic engineering of microorganisms plays an increasingly important role in industrial production. The genome-scale metabolic model (GSMM) integrates all known metabolic information in the organism to provide an optimal platform for global understanding of the metabolic state of the organism and rational guidance for metabolic engineering. As a model strain, Lactococcus lactis NZ9000 plays an important role in industrial fermentation, but there is still no specific genome-scale metabolic model for it. Based on genomic function annotation and comparative genomics, we constructed the first genome-scale metabolic model iWK557 of L. lactis NZ9000, which contains 557 genes, 668 metabolites, and 840 reactions, and further verified at both qualitative and quantitative levels, to provide a good tool for rationally guiding metabolic engineering.