For rare real-world data involving off-label drug use or comorbidity-associated polypharmacy,researchers have increasingly adopted target trial emulation to investigate drug repurposing for target indications.The success of such studies hinges on rigorous trial design and strict adherence to predefined protocols and standardized pipelines.Key elements in the trial design include the precise definition of inclusion and exclusion criteria,the selection of trial and control drugs and determination of treatment allocation time,the determination of appropriate efficacy endpoints for the target indication,the identification of causal estimands,and the development of robust strategies for confounding adjustment.The execution of the trial follows a structured process:screening eligible subjects,extracting relevant drug exposure data,constructing treatment and control groups,emulating the target trial,and ultimately generating hypotheses for drug repurposing through statistical inference.Propensity score methods,including stratification,matching and weighting techniques,are critical tools for addressing confounding bias and ensuring accurate estimation of causal effects.In recent years,creative progress has been made in target trial emulation,particularly in the calculation of propensity scores.Researchers have adopted advanced machine learning techniques,to enhance variable selection and have actively explored the use of innovative methods of digital intelligence technology like classification and regression trees,support vector machines,and deep learning for the application of propensity score calculation.Target trial emulation based on real-world data has achieved remarkable advancements in drug repurposing,demonstrating broad application prospects,particularly in cardiovascular diseases,metabolic disorders,Alzheimer's disease,and cancer.

For rare real-world data involving off-label drug use or comorbidity-associated polypharmacy,researchers have increasingly adopted target trial emulation to investigate drug repurposing for target indications.The success of such studies hinges on rigorous trial design and strict adherence to predefined protocols and standardized pipelines.Key elements in the trial design include the precise definition of inclusion and exclusion criteria,the selection of trial and control drugs and determination of treatment allocation time,the determination of appropriate efficacy endpoints for the target indication,the identification of causal estimands,and the development of robust strategies for confounding adjustment.The execution of the trial follows a structured process:screening eligible subjects,extracting relevant drug exposure data,constructing treatment and control groups,emulating the target trial,and ultimately generating hypotheses for drug repurposing through statistical inference.Propensity score methods,including stratification,matching and weighting techniques,are critical tools for addressing confounding bias and ensuring accurate estimation of causal effects.In recent years,creative progress has been made in target trial emulation,particularly in the calculation of propensity scores.Researchers have adopted advanced machine learning techniques,to enhance variable selection and have actively explored the use of innovative methods of digital intelligence technology like classification and regression trees,support vector machines,and deep learning for the application of propensity score calculation.Target trial emulation based on real-world data has achieved remarkable advancements in drug repurposing,demonstrating broad application prospects,particularly in cardiovascular diseases,metabolic disorders,Alzheimer's disease,and cancer.

Objective To analyze the serotype distribution and antibiotic resistance characteristics of Salmonella strains isolated in Guangdong province for better understanding the condition of Salmonella infection in patients with diarrhea.Methods Fecal samples collected from patients with diarrhea in Guangdong province were used to isolate Salmonella strains.Biochemical analysis was performed to identify these isolated strains.Serotyping and antimicrobial susceptibility testing were carried out for further analysis of the isolated Salmonella strains.Results The rate of Salmonella infection was 7.64％in 2015, and the male to female patient ratio was 1.52∶1.A total of 2 377 patients of all age groups were positive for Salmonella infection and the patients aged 0-6 years accounted for 81.74％.The isolation rate of Salmonella strains in the summer and autumn was higher than that in the winter and spring (10.73％ vs 4.24％;X2=463.77, P<0.01).The Salmonella isolation rates in different areas were as follows: 16.82％ in Zhuhai, 15.85％ in Heyuan, 11.81％ in Yangjiang, 10.68％ in Jiangmen, 8.49％ in Zhongshan, 8.07％ in Maoming, 8.05％ in Jieyang, 7.35％ in Shaoguan, 6.97％ in Foshan, 6.03％ in Dongguan, 5.48％ in Guangzhou and 0.00％ in Zhanjiang.And the differences between different regions were statistically significant (X2=367.67, P<0.01).The 2 377 isolated Salmonella strains were classified into 108 serotypes except for oneSalmonella strain that could not be classified.The top four predominant serotypes were 4,5,12:i:-, Salmonella enteritidis,Salmonella stanley and Salmonella typhimurium.Most Salmonella strains were sensitive to imipenem, azithromycin, ceftazidime, cefotaxime and trimethoprim/sulfamethoxazole, but multidrug resistance was common among those strains.Conclusion Salmonella serotypes of 4,5,12:i:-and Salmonella enteritidis are the predominant pathogens causing human Salmonella infections in Guangdong province.Ceftazidime and cefotaximeare are preferred in the treatment of Salmonella infections.Surveillance for drug resistance in Salmonella should be strengthened as multidrug resistant strains have become a serious problem in Guangdong province.

Objective To prepare simulated stool specimens for proficiency testing ( PT) by mix-ing lentils with Salmonella, Shigella and Escherichia coli strains and to establish an assessment scheme for the detection of Salmonella and Shigella in clinical samples. Methods Salmonella, Shigella and Escherich-ia coli strains were respectively spiked to lentils in Cary-Blair transport medium to create simulated stool specimens. Various ratios of Escherichia coli to Salmonella strains were spiked to lentils to prepare mixed simulated stool specimens. The accuracy and stability of prepared stool samples for PT were tested in-house. Results of sample detection were collected from participating laboratories for further external quality assess-ment. Results The Escherichia coli and Salmonella strains mixed at ratios of 100 ∶ 1 to 106 ∶ 1 could be ef-ficiently isolated from the media. Enrichment was needed in order to effectively isolate Salmonella strains from the media when the ratios of Escherichia coli to Salmonella strains were 104 ∶ 1 to 106 ∶ 1. Of the16 participating laboratories, 14 laboratories (87. 5%) received a grade of“satisfactory” and the other 2 labo-ratories (12. 5%) received a grade of “mainly satisfactory”. Conclusion The simulated stool specimens and the PT procedures designed in this study were suitable for proficiency testing program on the detection of Salmonella, Shigella and other similar microbes.

Objective To understand the effect ofserotyping on Salmonella isolates,by use of Microsphere-based Liquid Array method,among diarrhea patients,in Guangdong.Methods Salmonella isolated from humans in Guangdong province were serotyped on the Microsphere-based Liquid Array platform with SSA kit.Results A total of 4 942 Salmonella strains with 189 serotypes,were identified in Guangdong province in 2010-2014.The top 100 serotypes accounted for 98.08％ (4 847/4 942) of all the strains.98％ of the top 100 species serotypes could completely be serotyped with SSA kit.In order to detect O antigen among 198 isolates with SSA kit,181 strains were carrying the O antigen,with the coincidence rate as 100％.However,under the SSA,98.32％ (528/537) of the H antigen could be detected and were consistent with the traditional serum agglutination test.The coincidence rate of fljB gene was 93.09％ (175/188),with false negative rate and false positive rate of fljB gene as 7.35％ (9/134) and 7.41％ (4/54) respectively.The coincidence rate of sdf gene and Vi gene were 100％.11 out of the 12 Salmonella strains could not be serotyped under the traditional methods but were successfully serotyped by the molecular serotyping method.Conclusions Using the SSA kit,more than 96％ of the anthropogenic Salmonella strains could be serotyped in Guangdong province.Comparing with the traditional methods,the coincidence rate of serotyping appeared over 98％.Under the Microsphere-based Liquid Array techniques,the molecular serotyping method appeared faster and more accurate on Salmonella serotyping than those traditional methods.

Objective To investigate the value of mesenteric vascular CTA in the diagnosis of small intestinal neoplasms.Methods A retrospective analysis of mesenteric CTA from January 2008 to April 2013 was conducted in 51 patients with pathologically proven small intestinal neoplasms.Features of intestinal neoplasms CTA signs including neoplasm feeding artery,draining vein,mesangial side vasa recta and the formed neoplasm vessels,were observed.Two radiologists individually used two methods,namely intestinal tumor feeding artery positioning method and Cole fractionation method,for diagnosis and localization diagnosis of tumor,and also for comparing the results with those of surgical pathology.McNemar Chi-square test was adopted to evaluate the diagnosis differences between the two physicians and between the two methods by the same physician.Kappa value was used to assess the consistency of the results.Results Features of intestinal tumors CTA signs:12 cases of enlarged neoplasm feeding artery,9 cases of early displayed draining vein,22 cases of enlarged mesangial side vasa recta,and 11 cases of vessels formed inside and around the neoplasm,single lesion for all and the largest lesion diameter≥ 5 cm for 37 cases.The accuracy of Cole fractionation method positioning and the feeding artery positioning were 84.31％(43/51) and 98.03％(50/51) respectively.Moderate consistency(Kappa=0.49,P＜0.01) was seen with Cole fractionation method by the two physicians and high consistency(Kappa=1.00,P＜0.01) with feeding artery positioning method.McNemar Chi-square test showed no significant difference between the two methods by the same physician and the consistency of the results from the two methods was passable(P were 0.062 and 0.125).Conclusion Mesenteric CTA can display the intestinal tumor feeding arteries and draining veins,and is helpful in identification of the relationship between the tumor and its surrounding blood vessels,which can improve the accuracy of pre-operative localization and qualitative diagnosis for small intestinal tumor.

To compare and evaluate the discriminatory ability and potential value of pulsed field gel electrophoresis (PF-GE) and multiple locus VNTRs analysis (MLVA) on the genotyping of Brucella ,a total of 60 strains of Brucella and three standards (16M ,544A ,1330S) were genotyped simultaneously by PFGE and MLVA .The result indicated that the similarity coefficient among the 63 isolates was from 72 .1-100 .0% by PFGE ,and could distinguish three species of B .melitensis ,B .su-is and B .abortus at the similarity level of 94 .4% .There were 14 clusters and 29 PFGE types identified by PFGE with discrim-inatory index (DI) of 0 .957 5 at the similarity level of 100% ;the similarity coefficient among the 63 isolates was from 16 .9-100 .0% by MLVA ,and could distinguish three species of Brucella at the similarity level of 52 .3% .There were 8 clusters and 47 MLVA types identified by MLVA with discriminatory index (DI) of 0 .985 2 at the similarity level of 100% .It's suggested that PFGE and MLVA could be used to distinguish three species of Brucella in the similarity coefficient of certain ,but could not effectively distinguish the type in the same species .Both of these two methods could be used for Brucella molecular typing , but MLVA is better than PFGE for its relatively higher discriminating ability .

Objective To investigate the polymorphism of Brucella melitensis biovar 3 ( B.melitensis biovar 3) strains isolated from Guangdong province .Methods PCR assays followed by agar-ose gel electrophoresis and capillary electrophoresis based on the multiple locus variable number of tandem repeats (VNTR) analysis (MLVA) were performed to analyze 43 clinic isolates of B.melitensis biovar 3 strains isolated from clinical patients in Guangdong province .Results MLVA typing showed that the simi-larities of the analyzed locus among 43 strains of Brucella ranged from 68.2%to 100%.32 genotypes identi-fied among the isolates were identical (100%similarity).27 out of 43 strains (62.8%) were single geno-types, while the other 16 strains (37.2%) belonged to 5 other genotypes with 2 to 5 strains in each of them . Conclusion B.melitensis biovar 3 isolates showed polymorphism distribution in Guangdong province as in-dicated by MLVA typing analysis .Single-genotype isolates accounted for 62.8% of all studied strains.No predominant genotype was found among all isolates .

Objective To develop a rapid and sensitive DNA microarray for Listeria monocytogenes detection.Methods A DNA microarray was developed using gyrB,ISR,16S rRNA,23S rRNA,hlyA,iap and prfA as the target genes and tested against 18 different species of known reference for repeatability,sensitivity,and specificity to verify the effectiveness of the chip.Results After testing of samples by the LM array,results show that the 70 mer Oligos synthesized by IDT are superior to the Oligos synthesized by Sagon with respect to both probe spotting or samples detection.The comparison of 3 spotting probe concentrations of 10 μmol/L,40 μmol/L and 80 μmol/L demonstrated that the 10 pmol/L probes result in good detection signals equivalent to the 40 μmol/L and 80 μmol/L probes.The repeatability and sensitivity evaluated by sample testing on the LM array revealed that the chips developed in this study have good repeatability and the lower limit of sample detection is 0.9 ng DNA.The LM array can distinguish clearly and definitively between Listeria and non-Listeria bacteria in the sample.Conclusion The microarray is able to rapidly detect and identify Listeria monocytogenes.

Objective To investigate methods for prenatal molecular diagnosis of fetuses at high risk for X-linked adrenoleukodystrophy(X-ALD).Methods The amniotic fluid was obtained and genomic DNA was isolated from amniotic fluid cells.Maternal contamination was evaluated by paternity test.PCRRFLP,sequencing and denaturing high performance liquid chromatography(DHPLC)were used to detect the ABCD1 gene of fetal genome.Results In the pedigree 1,the PCR product(799 bp)of the fetus 1 and her father(normal control)could be digested with BcnI. No P560L mutation,which was present in the index patient,was detected in the ABCD1 gene from the genomic DNA of the fetus 1 using direct sequencing.In the pedigree 2,the PCR product(232 bp)of the fetus 2 and her father could not be digested with MaeI and no Q177X mutation,which was present in the propositus,was detected in the ABCD1 gene from the genomic DNA of the fetus 2 using direct sequencing.In the pedigree 3,the PCR product(271 bp)was digested with AciI.the pattern of the fetus 3 and the propositus being the same,and the R617C mutation was found in the ABCD1 gene from the genomic DNA of the fetus 3 using direct sequencing.In the pedigree 4,the PCR product(269 bp)was analyzed with the DHPLC,and the pattern of elution peaks of the fetus 4 and her father was similar,but different from that of the propositus.No K276E mutation was detectable in the ABCD1 gene from the genomic DNA of the fetus 4 by using direct sequencing.Judging from the sex of the fetuses,fetuses 1 and 2 were normal homozygotes,fetus 3 was an ALD hemizygote,and fetus 4 was a normal hemizygote.Conclusion A new protocol for X-ALD prenatal molecular diagnosis is proposed,which would ensure the accuracy of prenatal diagnosis.