According 1o the genome sequences of α.β,e,ι toxins of Clostridium perfringens in GenBank,four pairs of primers targeting α,β,ε,ι toxin genes were designed.After the multiplex PCR reaction condition was optimized,the multiplex PCR for identification and toxintyping of C.perfringens strains was developed.The specificity test showed that the expected fragments of C.perfringens reference strains including A.B,C,D,E five toxin types were amplified successfully from genomic DNA of C.perfringens,respectively.However,a band could not be amplified from Clostidrium novyi and Clostridium septicum as negative control groups.The sensitivity test showed that the limit detection of multiplex PCR was 9.0,17.8,12.2,13.8,18.5 pg DNA of A,B,C,D,E five toxin types C.perfringens,respectively.Repetitive testing showed that the established method had a good repeatability.Nine type A strains of and 1 type C strains of C.Perfringens from 21 clinical samples of dead goat were detected by the multiplex PCR developed in this study.This study establishes the multiple PCR method which not only can detect C.perfringens rapidly but also can identify five toxin types of C.perfringens.

Objective To systematically review the risk prediction models for intradialytic hypotension in maintenance hemodialysis patients,with a view to provide references for clinical practice.Methods PubMed,Embase,Web of Science,Cochrane Library,CINAHL,CNKI,VIP,Wanfang and CBM were searched from inception to May 29,2023.2 reviewers independently screened the literature,extracted information and assessed methodological quality using the Prediction Model Risk of Bias Assessment Tool.Results A total of 20 studies and 25 models were included with the sample size of 68～9 292 cases and the incidence of outcome events of 2.1～51％.Baseline systolic blood pressure,age,ultrafiltration rate,diabetes and dialysis duration were the top 5 predictors of repeated reporting of the models.20 models reported the area under the curve of ranging from 0.649 to 0.969,and 5 models reported calibration metrics.There were 9 internal validations and 4 combined internal and external validation models.The overall applicability of the 20 studies was good,but all had a high risk of bias,mainly in data analysis.Conclusion Research on risk prediction models for intradialytic hypotension in maintenance hemodialysis patients is still in the developmental stage.Future studies should improve the research design and reporting process,and validation studies of existing models should be carried out to further evaluate the effectiveness and feasibility in clinical practice.

OBJECTIVE To explore the efficacy and safety of intra-articular injection of ropivacaine combined with alfentanil for postoperative analgesia in patients who underwent knee arthroscopic surgery. METHODS A total of 60 patients who underwent knee arthroscopic surgery were collected from the Central Hospital of Enshi Tujia and Miao Autonomous Prefecture from March to September in 2022， and then divided into trial group and control group with random number table method， with 30 cases in each group. The control group received intra-articular injection of 0.25% ropivacaine 50 mg， and the trial group received intra-articular injection of 0.25% ropivacaine 50 mg+alfentanil 0.15 μg/kg.The first postoperative remedial analgesia time， the total amount of postoperative remedial drugs， numerical rating scale at rest （NRS-R） scores， numerical rating scale at movement （NRS-M） scores， heart rate， mean arterial blood pressure， and pulse oxygen saturation during exercise at different monitoring time points after surgery， the incidence of adverse drug reactions such as hypotension， respiratory depression， nausea， and vomiting after surgery were compared between 2 groups. RESULTS Compared with the control group， the first postoperative remedial analgesia time was significantly longer in the trial group， and the total amount of postoperative remedial drugs was significantly reduced （P＜0.001）. The trial group had lower NRS-R and NRS-M scores at each monitoring time point， with statistically significant differences （P＜0.001）， and there was an interactive effect between time and groups （P＜0.001）. The changes in heart rate， mean arterial blood pressure， and pulse oxygen saturation of patients in the trial group were relatively small， with no statistically significant differences （P＞0.05）， and there was no interactive effect between time and groups （P＞0.05）. There was no statistical significance in the incidence of adverse drug reactions between 2 groups， such as postoperative hypotension， respiratory depression， nausea， vomiting （P＞0.05）. CONCLUSIONS The intra- articular injection of ropivacaine combined with alfentanil shows good efficacy and safety for post-knee arthroscopic analgesia， and significantly prolongs the analgesic duration of ropivacaine.