Objective Streptococcus sanguis is a possible candidate bacterium for the caries replacement therapy, which has no advantages in the acidic environment.The aim of the study was to construct acid-resistant strains of Streptococcus sanguis, determine its acid tolerance, and explore the mechanism of its antagonism against Sterptococcus mutans.Methods By gradually reducing the pH value of the medium, we constructed acid-resistant strains of Streptococcus sanguis, observed their growth and measured their acid tolerance according to their survival rate against lethal pH.We evaluated the competitive relationship between Streptococcus sanguis and Streptococcus mutans by plate experiment and detected the changes of related acid resistance genes by real-time quantitative PCR.Results The growth of Streptococcus sanguis and its acid-resistant strains were limited by the pH value, and that of Streptococcus sanguis was better in either acidic or normal environment.The lethal pH value of Streptococcus sanguis was 3.6, that of its acid-resistant strains was 2.3, and the survival rate of the acid-resistant strains was 66.59% in the pH 3.6 environment.In comparison, the lethal pH value of Streptococcus mutans was 2.5, that of its acid-resistant strains was 2.1, and the survival rate of the acid-resistant strains was 2.55% in the pH 2.5 environment.In the presence of chloramphenicol, the acid-resistant strains could not survive in the original lethal pH.In the sub-lethal pH environment, the expressions of the acid resistance-related genes Groel and Dnak in the acid-resistant strains were significantly up-regulated as compared with those in the original Streptococcus sanguis (P<0.05).Conclusion Streptococcus sanguis has an acid adaptability and can enhance acid resistance in the sub-lethal pH environment.Acid-resistant Streptococcus sanguis in the replacement therapy may provide some new ideas for the treatment of dental caries.

Objective: To investigate the difference in invasiveness between vulvovaginal candidiasis(VVC) and recurrent vulvovaginal candidiasis(RVVC) strains, and to explore the effect of strains with different secreted aspartate protease(Sap) on vaginal local immunity. Methods: Vaginal secretions of VVC and RVVC patients were collected for fungus identification.Candida albicans(C.albicans) were taken for drug sensitivity analysis, 25 S rDNA genotyping, and detection of secreted aspartate protease(Sap) and phospholipase(Plb) activity.C.albicanswith different Sap activity were cultured with vaginal epithelial cells, and the levels of Interleukin(IL)-4, IL-8, IL-17 in cell supernatant were measured by ELISA. Results: Sap activity of VVCC.albicanswas stronger than that of RVVC. After infection withC.albicans, the secretion of IL-4, IL-8 and IL-17 by vaginal epithelial cells was higher, and IL-8 and IL-17 appeared earlier and lasted longer.C.albicanswith strong Sap enzyme activity could stimulate vaginal epithelial cells to secrete more cytokines. Conclusion Except for the Sap activity, there was no significant difference in the invasiveness between VVC and RVVC strains.C.albicanscould activate the vaginal host immune response in a short time. The lower Sap activity ofC.albicansin RVVC patients may be related to the protective factors secreted by the vaginal epithelium.

Transient receptor potential vanilloid-1(TRPV1) channel is a non-selective ligand-gated cationic channel with multiple activation mechanisms in the transient receptor potential subfamily. In recent years, a large number of studies have found that TRPV1 plays an important role in the field of cardiovascular diseases such as hypertension and atherosclerosis. With the in-depth study of traditional Chinese medicine, it has been found that Chinese medicine monomers and their active components can activate or inhibit TRPV1 channels, which has certain potential in the study of cardiovascular diseases. In this paper, the role of TRPV1 channel in cardiovascular diseases and the research progress of traditional Chinese medicine prevention and treatment of cardiovascular diseases based on TRPV1 channel are reviewed, in order to provide new ideas for prevention and treatment of cardiovascular system diseases.