Helicobacter pylori inhibited cell proliferation in human periodontal ligament fibroblasts through the Cdc25C/CDK1/cyclinB1 signaling cascade

PURPOSE: Several studies have shown that the oral cavity is a secondary location for Helicobacter pylori colonization and that H. pylori is associated with the severity of periodontitis. This study investigated whether H. pylori had an effect on the periodontium. We established an invasion model of a standard strain of H. pylori in human periodontal ligament fibroblasts (hPDLFs), and evaluated the effects of H. pylori on cell proliferation and cell cycle progression. METHODS: Different concentrations of H. pylori were used to infect hPDLFs, with 6 hours of co-culture. The multiplicity of infection in the low- and high-concentration groups was 10:1 and 100:1, respectively. The Cell Counting Kit-8 method and Ki-67 immunofluorescence were used to detect cell proliferation. Flow cytometry, quantitative real-time polymerase chain reaction, and western blots were used to detect cell cycle progression. In the high-concentration group, the invasion of H. pylori was observed by transmission electron microscopy. RESULTS: It was found that H. pylori invaded the fibroblasts, with cytoplasmic localization. Analyses of cell proliferation and flow cytometry showed that H. pylori inhibited the proliferation of periodontal fibroblasts by causing G2 phase arrest. The inhibition of proliferation and G2 phase arrest were more obvious in the high-concentration group. In the low-concentration group, the G2 phase regulatory factors cyclin dependent kinase 1 (CDK1) and cell division cycle 25C (Cdc25C) were upregulated, while cyclin B1 was inhibited. However, in the high-concentration group, cyclin B1 was upregulated and CDK1 was inhibited. Furthermore, the deactivated states of tyrosine phosphorylation of CDK1 (CDK1-Y15) and serine phosphorylation of Cdc25C (Cdc25C-S216) were upregulated after H. pylori infection. CONCLUSIONS: In our model, H. pylori inhibited the proliferation of hPDLFs and exerted an invasive effect, causing G2 phase arrest via the Cdc25C/CDK1/cyclin B1 signaling cascade. Its inhibitory effect on proliferation was stronger in the high-concentration group.

Design, screening and antimicrobial activity of novel peptides against / 南方医科大学学报

OBJECTIVE@#To construct antimicrobial peptides with potent antimicrobial activity, low cytotoxicity and efficient killing rate of for prevention and treatment of dental caries.@*METHODS@#We exploited the existing design strategies to modify reutericin 6 or gassericin A produced by species in the oral cavity based on their cationicity, amphipathicity and -helical structure. We examined their antimicrobial activities using bacterial susceptibility assay, their cytotoxicity through cytotoxicity assay and their killing rate of with time-kill assay. We further evaluated the candidate derivatives for their killing rate against , their antimicrobial activity against different oral pathogens and the development of drug resistance.@*RESULTS@#We constructed 6 AT-1 derivatives, among which AT-7 showed an MIC of 3.3 μmol/L against , and with a killing rate of 88.7% against within 5 min. We did not obtain strains of resistant to AT- 7 after induction for 10 passages.@*CONCLUSIONS@#Hydrophobicity and imperfect amphipathic structure are two key parameters that define the antimicrobial potency of the antimicrobial peptides. The imperfectly amphipathic peptide AT-7 shows the potential for clinical application in dental caries treatment.

Improved detection of Mycobacterium leprae rifampin resistance with nested-PCR / 中华检验医学杂志

Objective To improve the sensitivity of PCR for studying the rifampin resistant gene (rpoB) of M.Leprae from clinical samples.Method After comparing the results of PCR with Q-Solution (PCR Enhancer) and without Q-solution,Nested-PCR was then applied for the detection of rpoB gene.Results Although PCR Enhancer improves the amplification of rpoB gene, the sensitivity of routine PCR is only 45. 2%.The sensitivity of Nested-PCR for detecting mutants in rpoB gene can further increase to 90.5% after selection of optimum parameters.Conclusion The combinaion of PCR Enhancer and Nested-PCR improves the sensitivity and specificity of PCR for detection of rifampin resistant gene of M. Leprae.

Long term result of jejunum-interpositioned choledochoduodenostomy after resection of choledochocele / 中国普通外科杂志

Objective To evaluate the long-term result of jejunum-interpositioned choledochoduodenostomy with a antireflux valve after resection of choledochocele in 178 patients.Methods Postoperative patients were followed up by barium series of the upper digestive tract at different interval. To observe whether reflux remains and the severity of the reflux.Results142 out of the 178 cases (798%) were followed up, among them 21 cases (48%) without reflux, 26 cases (83%) with mild reflux, 51 cases (359%) with moderate reflux,and 28 severe cases(9%).16 cases(11.3%) had to undergo reoperation.Conclusion The technique has the effect of anti-reflux temporarily.Long-term follow-up found an increased morbidity of biliary infection, obstruction, perforation and stone formation.Severe postoperative complications necessitates a reoperation in some cases.