Antibiofilm activity against Staphylococcus aureus and content analysis of Taraxacum Officinale phenolic extract.

Taraxacum Officinale, commonly called dandelion, is herbaceous perennial belonging to the family of Asteraceae, having good antibacterial effects which are related to its phenolic substances. In this study, the effect of phenolic contents as well as the antibiofilm activity against Staphylo- coccus aureus of phenolic extract from T. Officinale were evaluated in vitro. With 70% metha- nol-water (v/v) as a solvent, the dandelion was extracted by ultrasonic assisted extraction method. Subsequent identification and quantification of phenol in extract was carried out using High Performance Liquid Chromatography (HPLC). The minimum inhibitory concentration and anti- bacterial kinetic curve of dandelion phenolic extract were analyzed by spectrophotometry. Changes in extracellular alkaline phosphatase (AKP) contents, electrical conductivity, intracellular protein contents, and DNA of S. aureus after the action of dandelion phenolic extract were determined to study its effect on the permeability of S. aureus cell wall and cell membrane. The results showed that chlorogenic acid (1.34 mg/g) was present in higher concentration, followed by lute- olin (1.08 mg/g), ferulic acid (0.22 mg/g), caffeic acid (0.21 mg/g), and rutin (0.19 mg/g) in the dandelion phenolic extract. The minimum inhibitory concentration (MIC) of dandelion phenolic extract against S. aureus was 12.5 mg/mL. The antibacterial kinetic curve analysis showed that the inhibitory effect of dandelion phenolic extract on S. aureus was mainly in the exponential growth phase. After applying the dandelion phenolic extract, the growth of S. aureus was signifi- cantly inhibited entering into the decay phase early. Furthermore, after the action of dandelion, the extracellular AKP contents of S. aureus, the electrical conductivity and the extracellular protein contents were all increased. The phenolic extract also affected the normal reproduction of S. aureus. These results suggest that dandelion has an inhibitory effect on S. aureus, and the mechanism of its action was to destroy the integrity of the cell walls and cell membranes.

[The first identification of epidemic clone of enterotoxic Escherichia coli O∶6 serogroup highly associated with azithromycin resistance in Shanghai].

Objective: To investigate the molecular characterization of adult diarrhea cases caused by enterotoxic Escherichia coli (ETEC) and explore the practical model of epidemiology for laboratory technique and data needs based on the surveillance network. Methods: Epidemiological design and sampling targeted adult cases ETEC caused diarrhea in epidemic season. The enterotoxin type, serogroup, resistance, colonization factor and molecular type of ETEC were identified. Multiple dynamic phenotypic characteristics of ETEC were indicated by multidimensional and multivariable data. Results: From 2016 to 2018, 84 eligible ETEC strains were detected. The dominant serums/toxins were O∶6 (STh), O∶25 (LT), O∶159 (STh), O∶153 (STh). O∶6 (STh+CS21), which replaced O∶25 and O∶159 as the popular clones in 2018. Six cases of O∶153 (STh+CFA/I+CS8+PT34) in outbreak in 2017 were imported ones. The resistance rates of ETEC strains detected in adults to sulfasoxazole, naproxinic acid, ampicillin and azithromycin were more than 30%, multidrug resistance (MDR) reached 58.3%. Serum/toxin types suggested that attenuated strains were more likely to become MDR. Molecular typing confirmed that the genetic similarity of the dominant clone of O∶6 serogroup (PT20-24) was higher than O∶25 and O∶159. There was a high correlation between the minimal inhibitory concentration (MIC) of azithromycin and the resistant gene mphA (87.5%, 28/32). O∶6 (STh+CS21+mphA) resistant clone was first detected in 2016. Conclusion: A new epidemic clone in adult ETEC diarrhea cases in Shanghai was O∶6 (STh+CS21+mphA). For the first time the association between azithromycin resistance gene mphA and a serum group of ETEC was observed. Multidimensional and multivariate analysis techniques based on epidemiology can help reveal the potential transmission pattern of ETEC for the accurate surveillance and early warning of outbreaks.

Proteomic analysis reveals the mechanisms of Mycena dendrobii promoting transplantation survival and growth of tissue culture seedlings of Dendrobium officinale.

AIMS: Dendrobium officinale is an important traditional Chinese medicinal herb. Its seedlings generally show low survival and growth when transferred from in vitro tissue culture to a greenhouse or field environment. In this study, the effect of Mycena dendrobii on the survival and growth of D. officinale tissue culture seedlings and the mechanisms involved was explored. METHODS AND RESULTS: Mycena dendrobii were applied underneath the roots of D. officinale tissue culture seedlings. The seedling survival and growth were analysed. The root proteins induced by M. dendrobii were identified using two-dimensional (2-D) electrophoresis and matrix-assisted laser desorption/ionization time-of-flight MS (MALDI-TOF-MS). Mycena dendrobii treatment significantly enhanced survival and growth of D. officinale seedlings. Forty-one proteins induced by M. dendrobii were identified. Among them, 10 were involved in defence and stress response, two were involved in the formation of root or mycorrhizae, and three were related to the biosynthesis of bioactive constituents. CONCLUSIONS: These results suggest that enhancing stress tolerance and promoting new root formation induced by M. dendrobii may improve the survival and growth of D. officinale tissue culture seedlings. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides a foundation for future use of M. dendrobii in the large-scale cultivation of Dendrobiums.

[Effect of Curcuma zedoaria (Berg.) Bosc on the myoelectric activity of uterus in rats and study of its mechanisms].

OBJECTIVE: To investigate the effect of Curcuma zedoaria on the myoelectric activity of uterus in virgin rats and study its mech anisms. METHOD: A pair of bipolar Ag-AgCl electrodes were implanted on the serosal surface of uterus in rats to observe the effect of C. zedoaria on the myoelectric activity of uterus before and after the five agonists were injected intraperitoneally. RESULT: Decoction of C. zedoaria significantly increases the spike area, the duration and the number of bursts of action potentials of the uterine smooth muscle and its effect is related dosage. Atropine and phentolamine decreased the exciting effect of C. zedoaria, whereas verapamil, diphenhydramine and indomethacin have no effect on the excitation of C. zedoaria. CONCLUSION: C. zedoaria has obvious exciting effect on the smooth muscle of uterus in rats, and its mechanisms may be associated with M-receptor and alpha-receptor.