Objective To investigate the effects of mannan-binding lectin(MBL) on TNF-α production induced by peptidoglycan (PGN) and its mechanism in human THP-1/CD14 monocytes.Methods The THP-1/CD14 cells were stimulated for 24 h with PGN at the indicated ratios after pretreated with human natural MBL at concentrations ranging from 1 to 20 mg/L for 2 h.The content of TNF-α and IL-6 in culture supernatants were detected by ELISA,and the levels of TNF-α and IL-6 mRNA expressions in these cells were determined by RT-PCR.FACS was used to investigate the interaction of MBL with THP-1/CD14 cells and the impact of MBL on PGN binding to THP-1/CD14 cells.Western blot was used to detect PGN-induced NF-κB translocation in THP-1/CD14 cells.Results ELISA showed that secretion of TNF-α and IL-6 from THP-1/CD14 cells could be induced by PGN ;The productions of TNF-α and IL-6 by THP-1/CD14 cells induced with PGN were profoundly inhibited by MBL at higher concentrations (10-20 mg/L) but not MBL at lower concentrations (1 mg/L).RT-PCR analysis also indicated that the mRNA expressions of TNF-α and IL-6 in THP-1/CD14 cells were decreased by MBL at higher concentration,compared to the corresponding THP-1/CD14 cells stimulated with PGN only.FACS showed that the binding of MBL to THP-1/CD14 cells was evident in a Ca2+-dependent manner.PGN could competitively inhibit the binding of MBL to THP-1/CD14 cells.MBL could competitively inhibit the binding of PGN to THP-1/CD14 cells by binding to THP-1/CD14 cells directly.Similarly,MBL at higher concentration (20 mg/L) decreased the NF-κB translocation in THP-1/CD14 cells.Conclusion MBL may inhibit TNF-α and IL-6 production induced by PGN in THP-1/CD14 cells through NF-κB signaling pathways,suggesting that MBL can play some roles in the regulation of PGN-induced inflammatory response.

Objective To investigate the antimicrobial susceptibility of clinical isolates of Corynebacterium striatum and the clinical characteristics of the patients infected or colonized with these strains.Methods The C.striatum strains isolated from clinical specimens were collected in Quanzhou First Hospital Affiliated to Fujian Medical University from July 2020 to September 2022.The clinical data were analyzed to examine the clinical characteristics of patients with C.striatum colonization or infection.The susceptibility of these strains to 18 antimicrobial agents were tested by broth microdilution method.The gyrA gene related to quinolone resistance determining region was amplified and sequenced to analyze the position of amino acid mutations.The ribosomal methylase gene ermX and aminoglycoside enzyme gene aphA1 were amplified by PCR and sequenced.Results Antimicrobial susceptibility testing indicated that all of the 72 strains were susceptible to vancomycin,linezolid and daptomycin.All stains were resistant to ceftriaxone,ciprofloxacin and moxifloxacin.The C.striatum strains showed high resistance rate to penicillin(87.5％),cefepime(95.8％),meropenem(95.8％),trimethoprim-sulfamethoxazole(90.3％),erythromycin(98.6％)and clindamycin(98.6％),but relatively lower resistance rate to gentamycin(25.0％),tetracycline(30.6％)and rifampicin(23.6％).Sequencing analysis indicated that 3 strains of C.striatum had single mutation of gyrA gene(Ser87Val),67 strains had double mutations(Ser87Phe,Asp91Ala or Ser87Tyr,Asp91Ala)and 2 strains had three point mutations(Ser87Phe,Ala88Pro and Asp91 Ala),which was newly identified in this study.The ermXgene was detected in all of the isolates and the prevalence of aphA1 gene was 43.1％.The 72 strains of C.striatum were mainly isolated from ICU(65.2％)and lower respiratory tract specimen(91.6％).The average age of patients was 68.0±15.3 years old.About 72.2％(52/72)of the C.striatum strains were isolated from the patients with infection and 27.8％(20/72)were colonizers.Compared to the patients colonized with C.striatum,the patients with C.striatum infection had statistically significant higher percentages of hospital stay ≥ 28 days,cerebral hemorrhage,disturbance of consciousness and disease deterioration(P＜0.05).Conclusions All of the 72 C.striatum isolates were multidrug resistant,and the outcome of patients with C.striatum infection was relatively poor.

With rapid development of information technology,blended teaching model has gradually become mainstream teaching model in most colleges and universities.How to evaluate students'learning effect and analyze factors that affect students'per-formance is a key research direction of this teaching model.Taking blended teaching of Medical Immunology course in Xinxiang Medical University as an example,this paper introduces implementation process and evaluation system of blended teaching,analyzes main factors affecting students'performance and learning effect,and focuses on discussing influence of formative evaluation and"flipped classroom"on students'academic performance.