Tetrodotoxin（TTX）is a potent neurotoxin known for its specific sodium channel blocking effects, widely used in biomedical research. While TTX has been identified in various marine organisms, its true origin remains unclear, and the specific biosynthetic pathways are yet to be elucidated. The reported sources of TTX and the progress in research on TTX biosynthesis were summarized, with a focus on potential microbial sources of TTX, which could provide scientific reference for the production and biosynthesis studies of TTX.

Objective To analyze the epidemiological characteristics of norovirus outbreaks in Haidian District, Beijing, and to provide a reference for epidemic prevention and control. Methods Descriptive epidemiological methods were used to organize and statistically analyze the norovirus outbreak data reported from 2016 to 2022. Results A total of 26 outbreaks of norovirus were reported in Haidian District, with a total of 1595 cases and an attack rate M (Q_R) of 8.23 (16.33)%. There were 24 cases of norovirus type GII (92.31%), 1 case of type GI (3.85%), and 1 case of mixed infection of virus type GI/GII (3.85%). The highest number of reported outbreaks occurred in March and April, with 17 cases, accounting for 65.38%. The highest number of reported cases was in November and December, with 785 cases, accounting for 44.92%. The case age M (Q_R) was 18 (14) years old. The detection rate of positive samples in different age groups had statistical significance（χ²=12.021, P=0.007). The 26 outbreaks were mainly distributed in collective units such as schools, preschool institutions, and enterprises and institutions. There were a total of 11 outbreaks related to foodborne transmission, with 923 cases, accounting for 57.87%. Diarrhea was positively correlated with the age of the cases (r_s=0.572, P<0.001), while vomiting was negatively correlated with the age of the cases (r_s=-0187, P<0.001). The time interval between the onset of acute gastroenteritis symptoms in the first case and the reporting of the epidemic was positively correlated with the duration of the epidemic (r_s=0.586, P=0.002). Conclusion It is necessary to strengthen the prevention and control of norovirus in schools (primary and secondary schools and colleges), strictly implement health monitoring and regular screening for kitchen workers, carry out publicity and education, detect cases as early as possible, report the epidemic in a timely manner, and effectively reduce the scale of the epidemic and prevent its spread.

Objective To examine the changing prevalence and antimicrobial resistance profiles of Burkholderia cepacia in 52 hospitals across China from 2015 to 2021.Methods A total of 9 261 strains of B.cepacia were collected from 52 hospitals between January 1,2015 and December 31,2021.Antimicrobial susceptibility of the strains was tested using Kirby-Bauer method or automated antimicrobial susceptibility testing systems according to a unified protocol.The results were interpreted according to the breakpoints released in the Clinical & Laboratory Standards Institute(CLSI)guidelines(2023 edition).Results A total of 9 261 strains of B.cepacia were isolated from all age groups,especially elderly patients.The proportion was 11.1％(1 032 strains)in children,significantly lower than the proportion in adults.About half(46.5％,4 310/9 261)of the strains were isolated from patients at least 60 years old and 42.3％(3 919/9 261)of the strains were isolated from young adults.Most isolates(71.1％)were isolated from sputum and respiratory secretions,followed by urine(10.7％)and blood samples(8.1％).B.cepacia isolates were highly susceptible to the five antimicrobial agents recommended in the CLSI M100 document(33rd edition,2023).B.cepacia isolates showed relatively higher resistance rates to meropenem and levofloxacin.However,the resistance rates to ceftazidime,trimethoprim-sulfamethoxazole,and minocycline remained below 8.1％.The percentage of B.cepacia strains resistant to levofloxacin was the highest compared to other antibiotics in any of the three age groups(from 12.4％in the patients＜18 years old to 20.6％in the patients aged 60 years or older).Conclusions B.cepacia is one of the clinically important non-fermenting gram-negative bacteria.Accurate and timely reporting of antimicrobial susceptibility test results and ongoing antimicrobial resistance surveillance are helpful for rational prescription of antimicrobial agents and proper prevention and control of nosocomial infections.

Objective To investigate the cerebral protective role of Duzhi pills on ischemic stroke rats and its mechanisms.Methods The healthy male SD rats were assigned to 5 groups:sham group,model group,Duzhi pill low-dose group(1.0 g/kg a day),Duzhi pill high-dose group(2.0 g/kg a day),or argatroban group(positive control).The low-dose and high-dose groups of Duzhi pills were intragastrically administered once a day for 8 d,while the other groups were intragastrically administered with the same amount of normal saline.Except the sham group,the middle cerebral artery occlusion(MCAO)cerebral ischemia-reperfusion model was established by suture method at 0.5 h after intragastric administration on the 8th day in other groups,and the ischemia duration was 90 min.Argatroban group was given a single dose(3.0 mg/kg)of argatroban via caudal vein at the same time of reperfusion.After 24 h of cerebral ischemia,the area of cerebral infarction,degree of cerebral infarction and neurological function injury were evaluated by 2,3,5-triphenyltetrazolium chloride(TTC)staining,Nissl staining and neurobehavioral score,respectively.The levels of inflammatory factors(transforming growth factor-β1[TGF-β1]and interleukin-1β[IL-1β])in the brain after cerebral ischemia were detected by enzyme-linked immunosorbent assay(ELISA),and the coagulation indexes were detected by an automatic coagulation analyzer.The scavenging ability of Duzhi pills on free radicals was analyzed by 2,2-diphenyl-1-picrylhydrazyl(DPPH)scavenging experiment.Results High-dose Duzhi pills reduced the cerebral infarction area,decreased the deep Nissl staining score of neural cells,and improved the symptoms of neurobehavioral defects in MCAO rats(compared with the model group,all P＜0.01).The levels of IL-1β and TGF-β1 in the ischemic brain tissue of the model group were significantly increased(compared with the sham group,both P＜0.01),while the levels of IL-1β and TGF-β1 in the brain tissue of the rats treated with low-dose and high-dose Duzhi pills were significantly decreased(compared with the model group,all P＜0.01).The coagulation index fibrinogen level in the model group was significantly higher than that in the sham group(P＜0.01),and both low-dose and high-dose Duzhi pills could inhibit the production of fibrinogen(compared with the model group,both P＜0.01).DPPH scavenging test results showed that Duzhi pills could scavenge free radical,the half inhibitory concentration was(1.33±1.11)mg/mL,and the slope of the curve was 1.378±0.145.Conclusion Duzhi pills play a cerebral protective role in ischemic stroke rats.The mechanism may be related to the inhibition of fibrinogen production,the reduction of inflammatory factors(TGF-β1 and IL-1β),and the antioxidant effects.

Objective To screen for key genes and important pathways common for different etiologies of acute kidney injury(AKI)by pathway-associated deep neural network and multiple machine learning algorithms.Methods AKI microarray datasets GSE30718,GSE37838,GSE53769,GSE108113,GSE125779,GSE99325,and GSE174020 downloaded from the Gene Expression Omnibus(GEO)database were merged,including 60 kidney samples from AKI patients and 79 kidney samples from healthy controls.They were divided(8∶2)into training sets and test sets,and were used to train and evaluate pathway-associated deep neural network and 4 machine learning algorithms,including least absolute shrinkage and selection operator(LASSO),random forest(RF),support vector machine-recursive feature elimination(SVM-RFE),and extreme gradient boosting(XgBoost),to screen for common key genes and pathways of different etiologies of AKI.The downloaded datasets GSE99340 and GSE1563 were merged,including 43 kidney samples from AKI patients and 36 kidney samples from healthy controls,which were used as external validation sets for LASSO model and nomogram performance test based on the final screened genes.The pathway-associated deep neural network and machine learning algorithms were evaluated using receiver operating characteristic curves,precision,recall,accuracy,and F1-score.The immune cell infiltration characteristics were explored in AKI via cell-type identification by estimating relative subsets of RNA transcripts(CIBERSORT),and Pearson correlation coefficients were used to evaluate the correlation between the final screened common key genes and immune cell infiltration levels.Results The pathway-associated deep neural network trained by 5-fold cross validation produced an area under curve(AUC)of 0.914 5±0.007 0,a precision of 0.750 0±0.044 0,a recall of 0.923 1±0.048 0,an accuracy of 0.838 7±0.016 0,and an F1-score of 0.827 6±0.020 0 in the test set,yielding a robust and highly accurate classification performance for AKI,and identified key pathways and a subset of candidate genes.The 4 machine learning algorithms all achieved high discriminative performance for AKI in the test set with AUC≥0.860,precision≥0.750,recall≥0.800,and F1-score≥0.774,and screened 7 common key genes for AKI with different etiologies,including CD86,C-X-C motif chemokine ligand 10(CXCL10),dynamin 2(DNM2),proto-oncogene FOS,transcription factor 12(TCF12),VGF nerve growth factor inducible(VGF),and A kinase anchoring protein 5(AKAP5).Based on the final screened common key genes,the LASSO model had an AUC of 0.940 4 for the test set and an AUC of 0.944 4 for the external validation,and the model showed a very high discriminatory ability for the AKI,which demonstrated the overall regulatory performance of the genes.The nomogram constructed based on the screened 7 genes demonstrated the highest classification performance with an AUC of 0.928 9,validating the outstanding contribution and overall action performance of the screened individual genes.Immune cell infiltration analysis showed that there were significant differences in B cells na?ve,mast cells activated,monocytes,macrophages M1,B cells memory,and dendritic cells activated between AKI samples and healthy control samples(all P＜0.05).Macrophages M1 and monocytes were positively correlated with CD86 and CXCL10,mast cells activated were positively correlated with FOS,and B cells na?ve were negatively correlated with CD86 and CXCL10(all P＜0.01).Mast cells activated were positively correlated with VGF and negatively correlated with CD86 and TCF12,while memory B cells were positively correlated with CD86(all P＜0.05).Conclusion Strategy combining pathway-associated deep neural network and multiple machine learning classifiers can mine high-value key genes from high-dimensional,complex and heterogeneous transcriptomic data as potential targets for therapeutic interventions in AKI.

ObjectiveTo explore the effect of serum containing Zhenwutang on myocardial mast cell apoptosis induced by angiotensin Ⅱ （AngⅡ） and the mechanism of the correlation between apoptosis and mitochondrial autophagy. MethodsIn this experiment， AngⅡ and serum containing Zhenwutang with different concentrations were used to interfere with H9C2 cardiomyocytes for 24 h， and the survival rate of H9C2 cardiomyocytes was detected by cell counting kit-8 （CCK-8） to screen the optimal concentration for the experiment. Enzyme-linked immunosorbent assay （ELISA） was used to detect the content of B-type natriuretic peptide （BNP） in cell culture supernatant， and immunofluorescence was used to detect the cell surface area to verify the construction of the myocardial mast cell model. Subsequently， the experiment was divided into a blank group （20% blank serum）， a model group （20% blank serum + 5×10^-5 mol·L^-1 AngⅡ）， low-， medium-， and high-dose （5%， 10% and 20%） serum containing Zhenwutang groups， an autophagy inhibitor group （1×10^-4 mol·L^-1 3-MA）， and autophagy inducer group （1×10^-7 mol·L^-1 rapamycin）. The apoptosis level of H9C2 cells and the changes of mitochondrial membrane potential were detected by flow cytometry. The lysosomal probe （Lyso Tracker） and mitochondrial probe （Mito Tracker） co-localization was employed to detect autophagy. Real-time fluorescence quantitative polymerase chain reaction （Real-time PCR） was used to detect Caspase-3， Caspase-9， B-cell lymphoma 2 （Bcl-2）， Bcl-2-related X protein （Bax）， and cytochrome C （Cyt C） in apoptosis-related pathways and the relative mRNA expression of ubiquitin ligase （Parkin）， phosphatase and tensin homolog （PTEN）-induced kinase 1 （PINK1）， and p62 protein in mitochondrial autophagy-related pathways. Western blot was used to detect cleaved Caspase-3， cleaved Caspase-9， Bax， Bcl-2， and Cyt C in apoptosis-related pathways， phosphorylated ubiquitin ligase （p-Parkin）， phosphorylated PTEN-induced kinase 1 （p-PINK1）， p62， and Bcl-2 homology domain protein Beclin1 in mitochondrial autophagy-related pathways， and the change of microtubule-associated protein 1 light chain 3 （LC3） Ⅱ/Ⅰ ratio. ResultsCCK-8 showed that when the concentration of AngⅡ was 5×10^-5 mol·L^-1， the cell activity was the lowest， and there was no cytotoxicity. At this concentration， the surface area of cardiomyocytes was significantly increased （P<0.01）， and the content of BNP in the supernatant of culture medium was significantly increased （P<0.05）. Therefore， AngⅡ with a concentration of 5×10^-5 mol·L^-1 was selected for the subsequent modeling of myocardial mast cells. Compared with the blank group， the model group and the autophagy inhibitor 3-MA group had a significantly increased apoptosis rate （P<0.01） and significantly decreased mitochondrial membrane potential （P<0.01）. The results of immunofluorescence co-localization showed that compared with the blank group， the model group had a significantly decreased number of red and green fluorescence spots. The results of Real-time PCR showed that compared with that in the blank group， the relative mRNA expression of Bax， Caspase-3， Caspase-9， Cyt C， and p62 in the model group was significantly up-regulated （P<0.01）， while the relative mRNA expression of Bcl-2， Parkin， and PINK1 was significantly down-regulated （P<0.01）. In addition， the relative protein expression of Bax， cleaved Caspase-3， cleaved Caspase-9， Cyt C， and p62 was significantly up-regulated （P<0.01）. The LC3Ⅱ/Ⅰ was significantly decreased， and the relative protein expression of Bcl-2， p-Parkin， p-PINK1， and Beclin1 was significantly down-regulated （P<0.01）. Compared with the model group， the serum containing Zhenwutang groups and the autophagy inducer group had significantly decreased apoptosis rate （P<0.01）， and the decrease ratio of mitochondrial membrane potential is significantly lowered （P<0.01） in a dose-dependent manner. Additionally， both red and green fluorescence spots became more in these groups. In the 3-MA group， the number of red and green fluorescence spots decreased significantly. The relative mRNA expression of Bax， Caspase-3， Caspase-9， Cyt C， and p62 was significantly down-regulated （P<0.05， P<0.01）， while that of Bcl-2， Parkin， and PINK1 was significantly up-regulated （P<0.01）. In the serum containing Zhenwutang groups， the relative protein expression levels of Bax， cleaved Caspase-3， cleaved Caspase-9， Cyt C， and p62 were significantly down-regulated （P<0.05，P<0.01）. The LC3Ⅱ/Ⅰ was significantly increased， and the relative protein expression levels of Bcl-2， p-Parkin， p-PINK1， and Beclin1 were significantly up-regulated （P<0.01）. ConclusionThe serum containing Zhenwutang can reduce the apoptosis of myocardial mast cells and increase mitochondrial autophagy. This is related to the inhibition of intracellular Bax/Bcl-2/Caspase-3 apoptosis pathway and regulation of Parkin/PINK1 mitochondrial autophagy pathway.

Objective To summarize the changing prevalence of carbapenem resistance in Enterobacterales based on the data of CHINET Antimicrobial Resistance Surveillance Program from 2015 to 2021 for improving antimicrobial treatment in clinical practice.Methods Antimicrobial susceptibility testing was performed using a commercial automated susceptibility testing system according to the unified CHINET protocol.The results were interpreted according to the breakpoints of the Clinical & Laboratory Standards Institute(CLSI)M100 31st ed in 2021.Results Over the seven-year period(2015-2021),the overall prevalence of carbapenem-resistant Enterobacterales(CRE)was 9.43％(62 342/661 235).The prevalence of CRE strains in Klebsiella pneumoniae,Citrobacter freundii,and Enterobacter cloacae was 22.38％,9.73％,and 8.47％,respectively.The prevalence of CRE strains in Escherichia coli was 1.99％.A few CRE strains were also identified in Salmonella and Shigella.The CRE strains were mainly isolated from respiratory specimens(44.23±2.80)％,followed by blood(20.88±3.40)％and urine(18.40±3.45)％.Intensive care units(ICUs)were the major source of the CRE strains(27.43±5.20)％.CRE strains were resistant to all the β-lactam antibiotics tested and most non-β-lactam antimicrobial agents.The CRE strains were relatively susceptible to tigecycline and polymyxins with low resistance rates.Conclusions The prevalence of CRE strains was increasing from 2015 to 2021.CRE strains were highly resistant to most of the antibacterial drugs used in clinical practice.Clinicians should prescribe antimicrobial agents rationally.Hospitals should strengthen antibiotic stewardship in key clinical settings such as ICUs,and take effective infection control measures to curb CRE outbreak and epidemic in hospitals.

Objective To characterize the changing species distribution and antibiotic resistance profiles of respiratory isolates in hospitals participating in the CHINET Antimicrobial Resistance Surveillance Program from 2015 to 2021.Methods Commercial automated antimicrobial susceptibility testing systems and disk diffusion method were used to test the susceptibility of respiratory bacterial isolates to antimicrobial agents following the standardized technical protocol established by the CHINET program.Results A total of 589 746 respiratory isolates were collected from 2015 to 2021.Overall,82.6％of the isolates were Gram-negative bacteria and 17.4％were Gram-positive bacteria.The bacterial isolates from outpatients and inpatients accounted for(6.0±0.9)％and(94.0±0.1)％,respectively.The top microorganisms were Klebsiella spp.,Acinetobacter spp.,Pseudomonas aeruginosa,Staphylococcus aureus,Haemophilus spp.,Stenotrophomonas maltophilia,Escherichia coli,and Streptococcus pneumoniae.Each microorganism was isolated from significantly more males than from females(P＜0.05).The overall prevalence of methicillin-resistant S.aureus(MRSA)was 39.9％.The prevalence of penicillin-resistant S.pneumoniae was 1.4％.The prevalence of extended-spectrum β-lactamase(ESBL)-producing E.coli and K.pneumoniae was 67.8％and 41.3％,respectively.The overall prevalence of carbapenem-resistant E.coli,K.pneumoniae,Enterobacter cloacae,Pseudomonas aeruginosa,and Acinetobacter baumannii was 3.7％,20.8％,9.4％,29.8％,and 73.3％,respectively.The prevalence of β-lactamase was 96.1％in Moraxella catarrhalis and 60.0％in Haemophilus influenzae.The H.influenzae isolates from children(＜18 years)showed significantly higher resistance rates to β-lactam antibiotics than the isolates from adults(P＜0.05).Conclusions Gram-negative bacteria are still predominant in respiratory isolates associated with serious antibiotic resistance.Antimicrobial resistance surveillance should be strengthened in clinical practice to support accurate etiological diagnosis and appropriate antimicrobial therapy based on antimicrobial susceptibility testing results.

OBJECTIVE To observe the effects of measures dominated by intensifying link quality on prevention and control of carbapenem-resistant Klebsiella pneumoniae(CRKP)among general ICU patients.METHODS The conventional intervention measures were taken from Jan.2016 to Oct.2020,which was assigned as the pre-inter-vention period;the intervention measures dominated by enhancement of link quality were taken for the general ICU patients(the study group)from Nov.2020 to Oct.2021,which was set as the intervention period,the inter-vention measures were taken for the neurosurgery ICU patients and the surgery ICU patients(the control group).A two-group interrupted time series of a quasi-experimental study was analyzed,and whether or not the intervention measures could reduce the incidence of CRKP hospital-associated infection among the general ICU patients was evaluated.RESULTS A total of 23 713 case-times of patients from three ICU wards were enrolled in the study.The incidence of CRKP hospital-associated infection among the general ICU patients was 4.49 cases per thousand patient-days during intervention period,3.71 cases per thousand patient-days during pre-intervention pe-riod,and there was no significant difference(u=-1.412,P=0.079);it was lower than 7.06 cases per thousand patient-days during nearly one year before the intervention period(from Nov.2019 to Oct.2020),and there was significant difference(u=3.128,P=0.002).The result of analysis of the interrupted time series showed that there was significant difference in the slope change between the study group and the control group after the inter-vention(P=0.035),indicating that the intervention measures could reduce the incidence of CRKP hospital-associ-ated infection in the study group,and there was significant difference in the changing trend between the study group and the control group.CONCLUSIONS The prevention and control measures for CRKP dominated by the link quality management can effectively reduce the incidence of CRKP hospital-associated infection among the gen-eral ICU patients.The prevention and control strategies may provide reference for prevention and control of CRKP in ICUs of other medical institutions.

Objective To investigate the distribution and antibiotic resistance profiles of clinical isolates in Beijing Children's Hospital,Capital Medical University from 2016 to 2022.Methods All the strains isolated from inpatients in Beijing Children's Hospital during the period from 2016 to 2022 were analyzed.Antimicrobial susceptibility test was conducted by Kirby-Bauer method or automated system.Results were interpreted according to the breakpoints recommended in the CLSI Ml00 2022 edition.Results A total of 24 904 isolates were analyzed,including Gram-positive bacteria(49.4％)and Gram-negative bacteria(50.6％).The top three Gram-positive bacteria were Staphylococcus aureus(15.6％),coagulase-negative Staphylococcus(14.0％),and Streptococcus pneumoniae(8.9％).The top three Gram-negative bacteria were Klebsiella spp.(8.6％),Pseudomonas aeruginosa(8.6％),and Haemophilus influenzae(8.1％).The prevalence of methicillin-resistant strains was 30.9％in SS.aureus(MRSA)and 82.7％in coagulase-negative Staphylococcus(MRCNS).The prevalence of PRSP was 75.0％(24/32)in meningitis isolates and 2.6％(57/2 195)in non-meningitis isolates.Five strains of E.faecium and 10 strains of E.faecalis were found resistant to linezolid.Two strains of E.faecium were resistant to vancomycin.The prevalence of extended-spectrum beta-lactamases(ESBLs)and carbapenem-resistant strains(CREco)in E.coli isolates was 69.0％and 9.7％,respectively.The prevalence of ESBLs and carbapenem-resistant strains(CRKpn)in K.pneumoniae isolates was 73.7％,and 37.2％,respectively.The prevalence of carbapenem-resistant strains was 21.9％in P.aeruginosa isolates and 59.3％in A.baumannii isolates.β-lactamase was detected in 68.3％of the H.influenzae isolates.Conclusions Antimicrobial resistance is still serious in children.It is necessary to strength the surveillance of bacterial resistance and use antibiotics rationally in order to curb the spread of drug-resistant strains.