OBJECTIVES: To detect prfA and hly toxin genes of Listeria monocytogenes using polymerase chain reaction (PCR) and colloidal gold technology. METHODS: L. monocytogenes DNA was extracted by boiling method. With prfA and hly of L. monocytogenes as the target genes, the 5' ends of upstream and downstream primers of prfA gene were labeled with 6-FAM and biotin, and the 5' ends of upstream and downstream primers of hly gene were labeled with digoxin and biotin, respectively, to establish the toxin gene detection method. Using cloning transformation, sequencing analysis, cloning of positive control products, the detection kid was developed and its specificity, sensitivity, reproducibility and stability were tested, followed by verification with sample testing. RESULTS: The concentration of L. monocytogenes DNA extracted by boiling method was 148.81±0.97 ng/μL, and the A₂₆₀/A₂₈₀ ratio ranged from 1.8 to 2.0. The PCR products showed a 100% homology with the gene sequences in GenBank database after cloning, transformation and sequencing. The colloidal gold strip yielded positive results only for L. monocytogenes samples without cross-reactions with Staphylococcus aureus, Escherichia coli or Bacillus cereus, and its minimum detection limit was 10^-2 ng/μL, demonstrating a 10-fold greater sensitivity of the test than agarose gel electrophoresis. The test also showed good reproducibility of the results when performed by different operators with good stability of the test strips after storage for 6 to 12 months. The test results showed that this kit could accurately and quickly detect L.monocytogenes in the test samples. CONCLUSIONS The detection kit developed in this study can simultaneously detect prfA and hly toxin genes of L. monocytogenes with good specificity, sensitivity, reproducibility and stability for use in food safety inspection.
Listeria monocytogenes/isolation & purification* ; Gold Colloid ; Bacterial Toxins/genetics* ; Polymerase Chain Reaction/methods* ; Hemolysin Proteins/genetics* ; Bacterial Proteins/genetics* ; DNA, Bacterial/genetics* ; Food Microbiology ; Heat-Shock Proteins

Objective:To discuss the effect of quorum sensing-related gene expression on biofilm formation and drug resistance in clinically multidrug-resistant Pseudomonas aeruginosa,and to clarify the mechanism of enhacing drug resistance.Methods:A total of 77 strains of Pseudomonas aeruginosa were collected.Based on drug resistance,the strains were divided into multidrug-resistant group and sensitive group.The optimal biofilm formation conditions were determined using the microtiter plate method;biofilm formations of the stains in both groups was observed under an optical microscope;crystal violet staining was used to semiquantitatively detect biofilm formation ability of P.aeruginosa in both groups;microbroth dilution method was used to determine the minimal inhibitory concentration(MIC)values of the quorum sensing inhibitor(C-30)against Pseudomonas aeruginosa in both groups;RNA was extracted from two groups using a commercial kit,while RNA from planktonic state and biofilm state of multidrug-resistant strains was extracted using modified TRIzol method;real-time fluorescence quantitative PCR(RT-qPCR)method was used to detect the mRNA expression levels of quorum sensing-related genes(lasR/I,RhlR/I,PqsR/A)of the stains in multidrug-resistant group and sensitive group,as well as before and after adding the quorum sensing inhibitor C-30.Results:Among 77 strains of Pseudomonas aeruginosa,56 were multidrug-resistant(multidrug-resistant group)and 21 were fully sensitive(sensitive group).Optimal biofilm formation occurred at a bacterial concentration of 1.5×108 CFU·mL-1 with 48 h incubation.The biofilm positivity rate was 91%,with strongly positive,moderately positive,weakly positive,and negative biofilms accounting for 16%,34%,41%,and 9%,respectively.The biofilm positivity rate in multidrug-resistant strains was 96%,and biofilm formation ability in multidrug-resistant group was higher than that in sensitive group(P<0.05).When the concentration of C-30 was 8 mg·L-1 the biofilm formation in most Pseudomonas aeruginosa was inhibited,with enhanced suppression at higher concentrations.The absorbtion(A)value of both planktonic-state and biofilm-state RNA ranged from 1.8 to 2.0.The RT-qPCR results showed that compared with planktonic state,the expression levels of lasR/I,RhlR/I,and PqsR/A mRNA of the stains in biofilm state were significantly increased(P<0.01).Compared with non-inhibitor group,the expression levels of lasR/I,RhlR/I,and PqsR/A mRNA in biofilm state of inhibitor-treated group were significantly decreased(P<0.01).Conclusion:High expression of quorum sensing-related genes in multidrug-resistant P.aeruginosa promotes biofilm formation,thereby enhancing drug resistance.

Objective:To establish a rapid detection method for pathogenic microorganisms by combining loop-mediated isothermal amplification(LAMP)and clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated protein 12a(Cas12a)(CRISPR-Cas12a)system,and to evaluate its efficacy for detecting the thermolabile hemolysin(tlh)gene of Vibrio parahaemolyticus(Vp).Methods:Using the tlh gene of Vp as the target gene,LAMP primers and CRISPR RNA(crRNA)were designed to construct and optimize the optimal concentration ratio of each component in the LAMP-CRISPR detection system.Bacillus cereus,Staphylococcus aureus,and Escherichia coli were used as control groups,and the specificity,sensitivity,reproducibility and positive conformity rate were verified to establish a rapid LAMP-CRISPR/Cas12a method for detecting the tlh gene of Vp.Results:The method specifically detected Vp,while Bacillus cereus,Staphylococcus aureus,and Escherichia coli yielded negative results.The DNA extraction concentration of Vp was 190.67 mg·L-1 with an A(260)/(A280)ratio of 1.84.Under the reaction conditions of 37℃ with 80 cycles for 40 min using quantitative PCR(qPCR)method,when the concentrations of Cas12a protein and crRNA in the LAMP-CRISPR/Cas12a system were 50 nmol·L-1,the visual brightness and relative fluorescence intensity peaks were high.The sensitivity of LAMP CRISPR/Cas12a for detecting Vp DNA concentration could reach 10-6 mg·L-1.The reproducibility test results showed that different experimenters had consistent results in different experimental environments and times.Conclusion:The established LAMP-CRISPR/Cas12a method can rapidly detect the tlh gene of Vp with high sensitivity and specificity,and can achieve short-term visual detection in the field.

Medical microbiology experiment is faced with many problems in online teaching. This study adopts the teaching mode of online live broadcast + operation video + virtual experiment, and make up the operation gap to some extent through operation video and virtual experiment. The mode of assessment is subjective thinking question (closely following the operation process) + experiment design + literature review (focusing on the key technology or new technology of clinical assessment that cannot be carried out due to the limitation of conditions in traditional experiments, such as mass spectrometry, fluorescence quantitative PCR, and G-test), and it is helpful to understand students' mastery of teaching objectives, and the ability of comprehensive application and innovative thinking. The student questionnaire shows that most students hold a positive attitude towards the online experimental teaching mode, and the quality of students' homework shows that most students have a good learning effect.

Peptides that are composed of dextrorotary (d)-amino acids have gained increasing attention as a potential therapeutic class. However, our understanding of the in vivo fate of d-peptides is limited. This highlights the need for whole-body, quantitative tracking of d-peptides to better understand how they interact with the living body. Here, we used mouse models to track the movement of a programmed death-ligand 1 (PD-L1)-targeting d-dodecapeptide antagonist (DPA) using positron emission tomography (PET). More specifically, we profiled the metabolic routes of [⁶⁴Cu]DPA and investigated the tumor engagement of [⁶⁴Cu/⁶⁸Ga]DPA in mouse models. Our results revealed that intact [⁶⁴Cu/⁶⁸Ga]DPA was primarily eliminated by the kidneys and had a notable accumulation in tumors. Moreover, a single dose of [⁶⁴Cu]DPA effectively delayed tumor growth and improved the survival of mice. Collectively, these results not only deepen our knowledge of the in vivo fate of d-peptides, but also underscore the utility of d-peptides as radiopharmaceuticals.

The evolution, structure and antigenic epitopes prediction of Rana dybowskii antimicrobial peptide dybowskin-1ST were carried out using bioinformatics software available online. Its antibacterial mechanism and structural properties were analyzed, and its activity was verified by applying wound healing assay in mice and bacteriostatic assay in vitro. This provides the theoretical basis for the improvement of parental peptide and the development of novel derivative peptides. The software MEGA_X were used to conduct homology alignment and to construct a phylogenetic tree. The online software ProtParam, ProtScale, PeptideCutter, signal, TMHMM Server were respectively used to predict the physicochemical parameters, hydrophilia/hydrophobicity, shear sites, signal peptides, and transmembrane domains of dybowskin-1ST. The online software SOPMA, Jpred4, DNAstar Protean were used to predict the secondary structure of dybowskin-1ST, and SWISS-MODEL, I-TASSER were used to predict the tertiary structure. ABCpred and SYFPEITHI were respectively used to predict its B-and T-cell epitopes. The effect of dybowskin-1ST on the wound healing was observed on experimental mice. Kirby-Bauer method and dilution method were used to determine the bacteriostatic activity of dybowskin-1ST. The dybowskin-1ST consists of 59 amino acid residues, of which leucine accounts for 16.9%, with a molecular formula of C₃₁₈H₅₁₀N₈₀O₉₃S₂. Its theoretical isoelectric point is 5.10 and the charge is -2. The dybowskin-1ST and dybowskin-1CDYa are closely related phylogenetically. The secondary structure of dybowskin-1ST predicted by the three methods were similar, which consisted of α-helix (44.07%), extended strand (16.95%), β-turns (3.39%), and random coil (35.39%). The prediction of tertiary structure showed that dybowskin-1ST was mainly composed of α-helix, and it was regarded as a hydrophilic protein with signal peptide sequence. Subcellular localization analysis showed that the probability of secreting the mitochondrial targeted peptides was 0.944. Dybowskin-1ST is an extracellular protein with no transmembrane structure region, but contains seven phosphorylation sites, three T-cell epitopes and eight B-cell epitopes. The dybowskin-1ST promoted wound healing and effectively inhibited the growth of Escherichia coli and Staphylococcus aureus. However, it had limited antibacterial activity against fungi and drug-resistant bacteria. Although the structure of dybowskin-1ST is rich in α-helix, the verification experiments showed that its antibacterial ability needs to be enhanced. The reason may be that it is a negatively charged and hydrophilic protein, and amino acid modification with the aim of increasing the number of positive charges and changing the hydrophobicity may be used to obtain derived peptides with enhanced activity.
Amino Acid Sequence ; Animals ; Mice ; Phylogeny ; Pore Forming Cytotoxic Proteins ; Protein Structure, Secondary ; Ranidae

Ubiquitin specific peptidase 28 (USP28) is closely associated to the occurrence and development of various malignancies, and thus has been validated as a promising therapeutic target for cancer therapy. To date, only few USP28 inhibitors with moderate inhibitory activity have been reported, highly potent and selective USP28 inhibitors with new chemotypes remain to be discovered for pathologically investigating the roles of deubiquitinase. In this current study, we reported the synthesis and biological evaluation of new [1,2,3]triazolo[4,5-]pyrimidine derivatives as potent USP28 inhibitors. Especially, compound potently inhibited USP28 (IC = 1.10 ± 0.02 μmol/L,  = 40 nmol/L), showing selectivity over USP7 and LSD1 (IC > 100 μmol/L). Compound was cellularly engaged to USP28 in gastric cancer cells. Compound reversibly bound to USP28 and directly affected its protein levels, thus inhibiting the proliferation, cell cycle at S phase, and epithelial-mesenchymal transition (EMT) progression in gastric cancer cell lines. Docking studies were performed to rationalize the potency of compound . Collectively, compound could serve as a new tool compound for the development of new USP28 inhibitors for exploring the roles of deubiquitinase in cancers.

Objective Using of cumulative live birth rate(CLBR)per oocytes retrieved cycle,to assess the clinical outcomes of in vitro fertilization or intracytoplasmic sperm injection(IVF/ICSI),and to explore impact factors on CLBR following utilization of all fresh and frozen embryos in one complete IVF/ICSI cycle using gonadotropin-releasing hormone(GnRH)agonist, GnRH-antagonist and clomiphene mild stimulation protocols. Methods Of the patients who underwent IVF/ICSI from January 1st, 2014 to December 31st, 2015 in the First Affiliated Hospital, Nanjing Medical University, a total of 6 142 oocytes retrieved cycles were included. The clinical and laboratory parameters of different ovarian stimulation protocols, and the effects of the age, number of oocytes retrieved and number of embryos available on the CLBR of each oocytes retrieved cycle were analyzed.Results The CLBR was 69.0%(2 004/2 906)in the GnRH-agonist protocol versus 67.4%(644/955)in the GnRH-antagonist protocol (P>0.05); the CLBR of clomiphene mild stimulation protocol was 53.2%(1 215/2 281),significantly lower than those of the other two protocols (all P<0.05). The CLBR significantly decreased with age increased. When divided into four groups according to the patients′ age, we found that CLBR were not statistically significant using three different protocols in the 20-25 years old group(all P>0.05).There was a strong association between the number of oocytes retrieved and embryos available on CLBR. CLBR rose significantly with an increasing number of oocytes up to 6, then the rising trend slowed down. Patients were categorized into four groups according to the number of oocytes retrieved,CLBR was significantly higher using GnRH-antagonist protocol (50.0%)than mild stimulation protocol(37.0%)in low ovarian responder(0-4 oocytes)group(P<0.05). The CLBR were no significant difference among three protocols in normal(10-15 oocytes)and high responders(≥15 oocytes)group(all P>0.05).The incidence rate of ovarian hyperstimulation syndrome in GnRH-agonist protocols(5.2%,152/2 906)were significantly higher than those of GnRH-antagonist(4.4%, 42/955)and clomiphene mild stimulation protocols(1.5%,34/2 281;all P<0.05).Conclusions CLBR is an important index to assess the clinical outcomes of IVF/ICSI. Age, number of oocytes retrieved and embryos available could affect CLBR obviously. According to the different age and ovarian response of patients, we should design ovarian stimulation protocols based on target oocytes number in order to get higher CLBR and reduce complications.

Objective To investigate the impact of dyslipidemia on in-vitro fertilization or intracytoplasmic sperm injection (IVF/ICSI) pregnancy outcome in patients with polycystic ovary syndrome (PCOS).Methods From July 2013 to March 2016,468 PCOS patients with antagonist protocol in IVF/ICSI of First Affiliated Hospital of Nanjing Medical University,cycles were divided into dyslipidemia group (108 cases) and normol blood lipids group (360 cases) according to the serum cholesterol,triglyceride (TG),high-density lipoprotein,low density lipoprotein levels.The general condition and clinical outcomes of the two groups were analyzed retrospectively,including the implantation rate,clinical pregnancy rate,live birth rate and the incidence of moderate to severe ovarian hyperstimulation syndrome (OHSS),etc.Besides,stratified analysis and multivariate logistic regression analysis were used to correct the impact of body mass index (BMI).Results (1) Comparing the based data of dyslipidemia group and normal blood lipids group:age,years of infertility,basic FSH,basic LH,basic estradiol and other indexes had no significant differences (all P＞0.05),but BMI of dyslipidemia group was significantly higher than normal blood lipids group [(25.0±3.0) versus (23.1±3.0) kg/m2],difference had statistical significance (P＜0.01).(2) The high score embryo rate,endometrial thickness on the day of hCG injection,progesterone and LH levels on the day of hCG injection,moderate to severe OHSS rate and miscarriage rate in the two groups did not exhibit remarkable differences (all P＞0.05).However,the number of dominant follicle,retrieved oocyte number,estrogen level on the day of hCG injection,implantation rate,biochemical pregnancy rate,clinical pregnancy rate and the live birth rate in dyslipidemia group were significantly less than those of normal blood lipids group (all P＜0.05),the dose of gonadotropin (Gn) and days of stimulation were significantly higher compared with the normal blood lipids group,there were significant differences statistically (all P＜0.05).(3) Stratified analysis showed that no matter in BMI＜24 or BMI≥24 kg/m2 group,the dose of Gn and days of stimulation were significantly higher in the dyslipidemia group than those of the normal blood lipids group,the difference was statistically significant (P＜0.05).However,the number of oocytes retrieved,estrogen level on the day of hCG injection had obvious downtrend,and the difference was statistically significant (P＜0.05) in BMI≥24 kg/m2 group.Multivariate logistic regression analysis found that,even after the correction of BMI,dyslipidemia still had negative impact on implantation rate,biochemical pregnancy rate,clinical pregnancy rate and the live birth rate (P＜0.05).(4) Further analysis of the different components of blood lipids in the clinical pregnancy group and unobtained pregnancy group revealed that the level of triglyceride (TG) in the unobtained pregnancy group was significantly higher than that in the pregnancy group,and the difference was statistically significant (P＜0.05);logistic regression analysis also showed that the increase of TG levels was negatively correlated with the clinical pregnancy rate of PCOS patients (P＜0.05).Conclusions PCOS patients combined with dyslipidemia have a higher BMI,and dyslipidemia increases the dosage of Gn,reduces the implantation rate,clinical pregnancy rate and live birth rate,especially the increase of TG level,which has adverse effects on IVF/ICSI outcome in patients with PCOS.

ABSTRACT:Objective To assess the effect of prolonged laparoscopic surgery on peritoneal mesothelial cells and fibrinolysis in humans.Methods We examined prospectively 1 6 consecutive patients who underwent laparoscopic surgery (LAP)and 2 1 patients who underwent conventional open surgery (OP)for high-medium rectal cancer with curative intent.During the procedure,biopsy of the parietal peritoneum was made before operation and at 45 min,90 min,and 120 min after operation.The tissue-type plasminogen activator (tPA)and plasminogen activator inhibitor-1 (PAI-1 )were determined by enzyme-linked immunosorbent assay in peritoneal tissues.The cellular injury was detected by LDH assay.The proliferation was quantified by MTT assay.Results PAI-1 activity in the peritoneal tissue was significantly lower in LAP group than in the OP group.tPA activity decreased after 45min of open surgery,but there was no significant change in the LAP group.With time extension,the LDH activity increased and the proliferation of the mesothelial cells decreased.Conclusion Preservation of a prolonged hypofibrinolytic state by inhibition of PAI-1 up-regulation during LAP may predispose patients to less postoperative peritoneal adhesion. The cellular injury becomes apparent and the proliferation is inhibited during prolonged laparoscopic surgery.