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 evaluate the efficacy and safety of nebulized inhalation of recombinant human interferon (IFN) α1b injection in the treatment of respiratory syncytial virus (RSV) associated lower respiratory tract infections (pneumonia and bronchiolitis) in children.Methods:A randomized, double-blind, parallel, placebo-controlled add-on design was used.Children with pneumonia or bronchiolitis aged 2 months to 5 years who tested positive for RSV antigen within 72 hours of onset from 30 clinical trial sites including Beijing Children′s Hospital, Capital Medical University between February 2021 and December 2022 were included in this study and randomly divided into 2 groups at a ratio of 1∶1 based on a stratified-block method.Both groups received basic treatments such as cough control, asthma relieving, expectorant treatment, fever reduction, oxygen therapy, etc.The experimental group received additional nebulized inhalation of IFN α1b injection at a dose of 2.0 μg/(kg·time), twice a day.The control group received nebulized inhalation of placebo twice a day.Clinical efficacy was evaluated based on indicators such as the duration of clinical symptoms and signs, and the Kaplan-Meier method was used to calculate the median and 95% CI of the duration of clinical symptoms and signs.The Log-rank test was used to compared data between groups.Safety was assessed through the incidence of adverse reactions and laboratory tests, and the Chi-square test was used to analyze the difference between groups. Results:There were 123 children in the experimental group and 122 children in the control group.The median durations of all the 5 clinical symptoms and signs [including shortness of breath, wheezing, dyspnea (visible retractions), decreased transcutaneous oxygen saturation, and abnormal mental state] in the experimental group after treatment were slightly shortened than those in the control group [2.7 d(95% CI: 1.9-3.0 d)] vs.[2.9 d(95% CI: 2.6-3.6 d), P=0.027].The improvement in dyspnea (retractions) was especially pronounced in the experimental group, with a relief rate of 50.0% (0, 100%) on the first day of administration[compared with 0 (0, 50.0%) in the control group ( Z=2.002, P=0.025)].The median duration of dyspnea in the experimental group was nearly 1 day shorter than that in the control group [1.0 d(95% CI: 0.7-1.7 d) vs.1.8 d(95% CI: 1.0-2.5 d), P=0.046].There were no significant difference in hospital stay [6.0(5.0, 8.0) d vs.6.5(5.0, 8.0) d, Z=0.675, P=0.500], oxygen therapy duration [32.0(14.0, 96.3) h vs.39.0 (24.0, 83.2) h, Z=0.094, P=0.925], the recovery rate from clinical symptoms during treatment [(105/106, 99.1%) vs.(96/101, 95.0%)], and recurrence rate [(0/106, 0) vs.(2/101, 2.0%)] between the 2 groups (all P>0.05).However, the above-mentioned four indicators in the experimental group showed a trend of clinical benefits.The quantitative virus detection results showed that the RSV viral load in both groups decreased after treatment compared to before treatment.After 2 days of treatment, the decline rate of RSV viral load from the baseline was 0.90 lg copies/(mL·d) in the experimental group and 0.25 lg copies/(mL·d)in the control group, with a statistically significant difference ( P<0.05).Furthermore, there was no statistically significant difference in the incidence of adverse reactions between the 2 groups ( P>0.05).Importantly, no drug-related serious adverse reactions occurred in both groups. Conclusions:The nebulized inhalation therapy of IFN α1b demonstrates efficacy and safety in treating pediatric RSV associated lower respiratory tract infections.It particularly offers outstanding clinical therapeutic value for severe children.

Objective:To evaluate the efficacy and safety of nebulized inhalation of recombinant human interferon (IFN) α1b injection in the treatment of respiratory syncytial virus (RSV) associated lower respiratory tract infections (pneumonia and bronchiolitis) in children.Methods:A randomized, double-blind, parallel, placebo-controlled add-on design was used.Children with pneumonia or bronchiolitis aged 2 months to 5 years who tested positive for RSV antigen within 72 hours of onset from 30 clinical trial sites including Beijing Children′s Hospital, Capital Medical University between February 2021 and December 2022 were included in this study and randomly divided into 2 groups at a ratio of 1∶1 based on a stratified-block method.Both groups received basic treatments such as cough control, asthma relieving, expectorant treatment, fever reduction, oxygen therapy, etc.The experimental group received additional nebulized inhalation of IFN α1b injection at a dose of 2.0 μg/(kg·time), twice a day.The control group received nebulized inhalation of placebo twice a day.Clinical efficacy was evaluated based on indicators such as the duration of clinical symptoms and signs, and the Kaplan-Meier method was used to calculate the median and 95% CI of the duration of clinical symptoms and signs.The Log-rank test was used to compared data between groups.Safety was assessed through the incidence of adverse reactions and laboratory tests, and the Chi-square test was used to analyze the difference between groups. Results:There were 123 children in the experimental group and 122 children in the control group.The median durations of all the 5 clinical symptoms and signs [including shortness of breath, wheezing, dyspnea (visible retractions), decreased transcutaneous oxygen saturation, and abnormal mental state] in the experimental group after treatment were slightly shortened than those in the control group [2.7 d(95% CI: 1.9-3.0 d)] vs.[2.9 d(95% CI: 2.6-3.6 d), P=0.027].The improvement in dyspnea (retractions) was especially pronounced in the experimental group, with a relief rate of 50.0% (0, 100%) on the first day of administration[compared with 0 (0, 50.0%) in the control group ( Z=2.002, P=0.025)].The median duration of dyspnea in the experimental group was nearly 1 day shorter than that in the control group [1.0 d(95% CI: 0.7-1.7 d) vs.1.8 d(95% CI: 1.0-2.5 d), P=0.046].There were no significant difference in hospital stay [6.0(5.0, 8.0) d vs.6.5(5.0, 8.0) d, Z=0.675, P=0.500], oxygen therapy duration [32.0(14.0, 96.3) h vs.39.0 (24.0, 83.2) h, Z=0.094, P=0.925], the recovery rate from clinical symptoms during treatment [(105/106, 99.1%) vs.(96/101, 95.0%)], and recurrence rate [(0/106, 0) vs.(2/101, 2.0%)] between the 2 groups (all P>0.05).However, the above-mentioned four indicators in the experimental group showed a trend of clinical benefits.The quantitative virus detection results showed that the RSV viral load in both groups decreased after treatment compared to before treatment.After 2 days of treatment, the decline rate of RSV viral load from the baseline was 0.90 lg copies/(mL·d) in the experimental group and 0.25 lg copies/(mL·d)in the control group, with a statistically significant difference ( P<0.05).Furthermore, there was no statistically significant difference in the incidence of adverse reactions between the 2 groups ( P>0.05).Importantly, no drug-related serious adverse reactions occurred in both groups. Conclusions:The nebulized inhalation therapy of IFN α1b demonstrates efficacy and safety in treating pediatric RSV associated lower respiratory tract infections.It particularly offers outstanding clinical therapeutic value for severe children.

Objective To investigate the protective effect of Toll-like receptor (TLR)2/TLR9 agonists,Pam2 CSK4(Pam)and CpG ODN (CpG)on mice infected with Acinetobacter baumannii (Ab)in the lungs.Methods Female C57 mice (6～8 weeks old)were randomly divided into PBS,Pam,CpG and Pam+CpG groups.In 24 h after intranasal immunization with different doses of the corresponding agonists,the mice were given a lethal dose of Ab infection in the lungs,and the survival rates of the mice were observed.A sublethal dose lung infection model of Ab was then established,and the bacterial colonization in the blood,lungs,liver,kidneys and spleen was measured respectively in the mice after infection.HE staining was used to observe the pathological damages in the lungs and kidneys.The protective effect of the agonists in the immunized mice against Ab was examined at 1,3 and 7 d after immunization to explore the protective time window.Pam+CpG was used to stimulate A549 cells and RAW264.7 cells to investigate the killing or phagocytic effects on Ab.Results Compared to PBS,Pam+CpG treatment significantly improved the survival rate of the mice after a lethal dose of Ab lung infection (P<0.05,P<0.01 ),reduced bacterial colonization in the blood (P<0.01 ),lungs (P<0.01 ),liver (P<0.01 ),kidneys (P<0.01 )and spleen (P<0.01 )in the mice after sublethal challenge,and alleviated pathological damage caused by infection. Immunization at 1 or 3 d before infection significantly improved the survival rate (P<0.05 ),and the protective effect was the best in 3 d after immunization.Furthermore,compared to single PBS,Pam and CpG immunization,Pam+CpG significantly promoted the killing and phagocytic effects of A549 epithelial cells and RAW264.7 cells,respectively,against Ab (P<0.01 ).Conclusion Combined application of TLR2/TLR9 agonists exerts a significant protective effect on both lethal and sublethal infections of Ab,which might be by its promoting the killing or phagocytic effect of lung epithelial cells and macrophages against Ab.

Objective To construct lipid nanoparticles(lipopeptide-lipid nanoparticle,LP-LNP)with novel lipopeptides as adjuvants,and initially explore their synergistic effect on mRNA vaccines.Methods Two novel lipopeptides,SS-10 and SQ18,were designed and synthesized.Microfluidic technology was used to encapsulate lipopeptides in different proportions,as well as mRNAs encoding enhanced green fluorescent protein(eGFP),firefly luciferase(F-luc),and ovalbumin(OVA)into lipid nanoparticles to construct an mRNA delivery system with novel lipopeptides as adjuvants(LP-LNP).The particle size and polydispersity coefficient of LP-LNP were measured using dynamic light scattering.The activation effect on Toll-like receptors 2(TLR2)was detected using HEK-BlueTM mTLR2 reporter cells to screen the optimal lipopeptide ratio.The preferred LP-LNP-eGFP-mRNA was transfected into HEK293T cells,and the expression of eGFP was observed under a fluorescence microscope.In vivo imaging was used to investigate the expression level of LP-LNP-F-luc-mRNA in mice.Flow cytometry was used to evaluate the ability of LP-LNP-OVA-mRNA to induce the maturation of dendritic cells(DCs)in draining lymph nodes and cross-presentation of antigens after immunization.Results Lipopeptides SQ18 and SS-10 were incorporated into LNP at 0.50％and 0.75％molar ratios,respectively,to obtain LP-LNP with uniform particle size,high encapsulation efficiency,and good in vitro safety.The ability of this formulation to activate TLR2 was significantly stronger than the positive control Pam2CSK4(P＜0.01).The preferred LP-LNP obtained effective in vitro transfection,and LP-LNP prepared with SQ18 at 0.50％molar ratio had significantly better in vivo transfection efficiency than traditional LNP(P＜0.01),and significantly promoted the maturation of DCs in draining lymph nodes and cross-presentation of antigens(P＜0.05).Conclusion LP-LNP with novel lipopeptides as adjuvants can enhance the delivery capacity of mRNA and further improve the immune effect of mRNA vaccines.

Objective:To explore the diagnostic value of different machine learning models and optimal machine learning model combined with clinical data for diagnosing Hashimoto′s thyroiditis (HT).Methods:The thyroid gland images of 643 patients with 643 thyroid nodules who underwent preoperative ultrasound examination and had pathological results in the Second Affiliated Hospital of Xi′an Jiaotong University from December 2018 to March 2024 were retrospectively collected, and the images were divided into training set and test set according to a ratio of 7 to 3. Twenty ultrasound imaging omics models were constructed using pairwise combination of 5 feature screening components and 4 classifiers. The area under the curve (AUC) of each model in the test set was compared. Meanwhile, 3 basic network models were respectively used to construct deep learning models for diagnosing HT, and the diagnostic efficacies of the deep learning models and the ultrasound imaging omics models for HT were compared. The model with the greatest efficacy was selected as the optimal machine learning model. Further, the optimal machine learning model was combined with clinical data to construct a combined model. The ROC curves were plotted to compare the diagnostic efficacy of the optimal machine learning model and the combined model for HT.Results:In the comparison of the efficacies of ultrasound imaging omics models and deep learning models in diagnosing HT, the efficacy of stable feature screening-logistic regression (LR) model was the greatest, and the accuracy, sensitivity and specificity of using the LR model in diagnosing HT in the test set were 78%, 75%, 74%, respectively, with an AUC of 0.82(95% CI=0.76-0.88). After combining the LR model with clinical data, the accuracy, sensitivity, and specificity of the combined model in the test set were 87%, 74%, and 95%, respectively, with an AUC of 0.91(95% CI=0.87-0.95), which was strongly consistent with pathology (Kappa value=0.708, P<0.001). Conclusions:The optimal machine learning model (LR model) constructed in this study demonstrates a strong ability to diagnose HT and can accurately detect patients with atypical ultrasound manifestations of HT. The combination with clinical data can improve its diagnostic efficacy with higher accuracy and specificity.

Objective:To explore the diagnostic value of different machine learning models and optimal machine learning model combined with clinical data for diagnosing Hashimoto′s thyroiditis (HT).Methods:The thyroid gland images of 643 patients with 643 thyroid nodules who underwent preoperative ultrasound examination and had pathological results in the Second Affiliated Hospital of Xi′an Jiaotong University from December 2018 to March 2024 were retrospectively collected, and the images were divided into training set and test set according to a ratio of 7 to 3. Twenty ultrasound imaging omics models were constructed using pairwise combination of 5 feature screening components and 4 classifiers. The area under the curve (AUC) of each model in the test set was compared. Meanwhile, 3 basic network models were respectively used to construct deep learning models for diagnosing HT, and the diagnostic efficacies of the deep learning models and the ultrasound imaging omics models for HT were compared. The model with the greatest efficacy was selected as the optimal machine learning model. Further, the optimal machine learning model was combined with clinical data to construct a combined model. The ROC curves were plotted to compare the diagnostic efficacy of the optimal machine learning model and the combined model for HT.Results:In the comparison of the efficacies of ultrasound imaging omics models and deep learning models in diagnosing HT, the efficacy of stable feature screening-logistic regression (LR) model was the greatest, and the accuracy, sensitivity and specificity of using the LR model in diagnosing HT in the test set were 78%, 75%, 74%, respectively, with an AUC of 0.82(95% CI=0.76-0.88). After combining the LR model with clinical data, the accuracy, sensitivity, and specificity of the combined model in the test set were 87%, 74%, and 95%, respectively, with an AUC of 0.91(95% CI=0.87-0.95), which was strongly consistent with pathology (Kappa value=0.708, P<0.001). Conclusions:The optimal machine learning model (LR model) constructed in this study demonstrates a strong ability to diagnose HT and can accurately detect patients with atypical ultrasound manifestations of HT. The combination with clinical data can improve its diagnostic efficacy with higher accuracy and specificity.

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.

As a typical food safety industrial model strain, Bacillus subtilis has been widely used in the field of metabolic engineering due to its non-pathogenicity, strong ability of extracellular protein secretion and no obvious codon preference. In recent years, with the rapid development of molecular biology and genetic engineering technology, a variety of research strategies and tools have been used to construct B. subtilis chassis cells for efficient synthesis of biological products. This review introduces the research progress of B. subtilis from the aspects of promoter engineering, gene editing, genetic circuit, cofactor engineering and pathway enzyme assembly. Then, we also summarized the application of B. subtilis in the production of biological products. Finally, the future research directions of B. subtilis are prospected.
Bacillus subtilis/genetics* ; Bacterial Proteins/genetics* ; Gene Editing ; Metabolic Engineering ; Promoter Regions, Genetic

Objective To study the pharmacokinetics of raltitrexed using different ways of drug delivery, including femoral venous infusion, hepatic artery perfusion, hepatic artery injection of lipiodol suspension, hepatic artery perfusion followed by embolization with Gelfoam. Methods According to the administration way of raltitrexed, a total of 40 New Zealand rabbit models with VX2 liver tumor were randomly divided into group A (femoral venous perfusion), group B (hepatic arterial perfusion), group C (hepatic artery injection of lipiodol suspension), and group D(hepatic artery perfusion followed by embolization with Gelfoam). Drug concentration in plasma were determined by using LC-MS/MS method and the pharmacokinetic parameters were calculated. Results After administration of raltitrexed, the Tmax was 5 minutes in all 4 groups. In group A, B, C and D, the values were (5.88±1.39), (7.31±2.60), (9.86±5.10) and (7.19±2.27) respectively, with group C having the longest t1/2 value, which was significantly different with that of group A (P＜0.05); the (ng·ml-1·h-1) values were (2 056.40± 139.17), (1 389.21±180.28), (911.84±105.62) and (1 133.41±181.42)respectively, with the value of group A being obviously higher than that of group B, C and D (P＜0.05) and the value of group C being the lowest; the AUC0-t(ng· ml-1·h-1) values were (5 482.72±1 007.07), (4 156.99±1 475.77), (2 785.13±1 107.36) and (3 903.64±947.25) respectively, with the value of group A being remarkably higher than that of group B, C and D (P＜0.05) and the value of group C being the lowest. Conclusion Compared with the femoral vein infusion way, the ways of hepatic artery infusion, hepatic artery lipiodol suspension injection and hepatic artery perfusion followed by embolization with Gelfoam may promote more raltitrexed to deposit in the tumor area, thus, the curative effect is enhanced, the drug concentration in plasma is lowered and the side effects are alleviated.