Rhein against Staphylococcus xylosus by interfering with respiratory metabolism and inducing oxidative stress.

Currently, dairy mastitis caused by Staphylococcus xylosus poses a serious challenge for dairy farming. In this study, we explored the role and mechanism of rhein against S. xylosus with the hope of providing new research ideas to solve mastitis in dairy cows and ensure the source safety of dairy products. Through in vitro antimicrobial studies, we found that the minimum inhibitory concentration (MIC) of rhein was 64 µg/mL, and it significantly interfered with the formation of S. xylosus biofilm at sub-MIC. In experiments on mastitis in mice, rhein alleviated inflammation in mammary tissue, reduced the levels of TNF-α and IL-6, and decreased the number of S. xylosus. To explore the anti-S. xylosus mechanism of rhein, we identified the relevant proteins involved in carbon metabolism (Glycolysis/gluconeogenesis, TCA cycle, Fatty acid degradation) through proteomics. Additionally, proteins associated with the respiratory chain, oxidative stress (proteins of antioxidant and DNA repair), and nitrate respiration were also found to be upregulated. Thus, rhein may act as an antibacterial agent by interfering with the respiratory metabolism of S. xylosus and inducing the production of ROS, high levels of which alter the permeability of bacterial cell membranes and cause damage to them. We measured the concentrations of extracellular ß-galactosidase and nucleic acids. Additionally, SEM observation of S. xylosus morphology showed elevated membrane permeability and damage to the cell membrane. Finally, RT-PCR experiments showed that mRNAs of key proteins of the TCA cycle (odhA, mqo) and nitrate respiration (nreB, nreC, narG) were significantly up-regulated, consistent with proteomic results. In conclusion, rhein has good anti-S. xylosus effects in vitro and in vivo, by interfering with bacterial energy metabolism, inducing ROS production, and causing cell membrane and DNA damage, which may be one of the important mechanisms of its antimicrobial activity.

Preparation, characterization, and Staphylococcus aureus biofilm elimination effect of baicalein-loaded tyrosine/hyaluronic acid/ß-cyclodextrin-grafted chitosan nano-delivery system.

Staphylococcus aureus (S. aureus) is an important cause of infections associated with implanted medical devices due to the formation of bacterial biofilm, which can prevent the penetration of drugs, thus posing a serious multi-drug resistance. Methicillin-resistant Staphylococcus aureus (MRSA) is one of them. In order to enhance the biofilm elimination effect of Baicalein (BA), a BA-loaded Tyr/HA/CD-CS nano-delivery system was successfully prepared using ß-cyclodextrin grafted with chitosan (CD-CS), Hyaluronic Acid (HA), and D-Tyrosine (D-Tyr). The Tyr/HA/CD-CS-BA-NPs have a uniform particle size distribution with a particle size of 238.1 ± 3.06 nm and a PDI of 0.130 ± 0.02. The NPs showed an obvious inhibitory effect on planktonic bacteria with a MIC of 12.5 µg/mL. In vivo and in vitro tests showed that the NPs could enhance the elimination effect of BA on the MRSA biofilm. The results of Confocal Laser Scanning Microscopy (CLSM), Live & Dead Kit, and colony count experiments illustrated that Tyr/HA/CD-CS-BA-NPs could enhance the permeability of drugs to the biofilm and improve the ability to kill the biofilm bacteria, which may be an important mechanism to enhance the elimination of the MRSA biofilm. These findings will help develop new, effective medicaments for treating bacterial biofilm infections.

Temperature Field and Stress Analysis of the Heavy-Concrete Transfer-Purge Chamber of the Nuclear Power Plant.

A transfer-purge chamber (TPC) is a double-steel-plate, heavy-concrete, curved-surface composite structure composed of steel plates, heavy concrete, and shear connectors. It is an important facility in the external refueling system of a nuclear power plant (NPP), providing a safe and reliable biological shielding space for reactor refueling operations. Temperature load is one of the most important factors that must be considered in the design of NPP structures. The temperature loads experienced by the TPC during its life cycle include those encountered in both normal and abnormal operation, which are distinct. In this study, we investigated the steady state and transient-state temperature fields and stresses of a TPC structure under normal operation and after 48 h of abnormal operation, respectively, which were calculated using Abaqus finite element software and the directly coupled method. During normal operation, the temperature field of the structure shows relatively uniform changes, and the temperature gradient of the internal concrete in the direction of its thickness has a constant value of 0.245 °C/cm. At the junction between the transfer and purge sub-chambers of the TPC, under the influence of wall curvature and deformation constraints, the maximum tensile strain of heavy concrete is 8.84 × 10-3, the maximum compressive strain is 2.04 × 10-3, the peak stress of the steel plate is 98.305 MPa, and the peak stress of the stud is 306.725 MPa. After 48 h of abnormal operation, the temperatures of the inner surface of the heavy concrete of the wall, the inner steel plate of the wall, the outer surface of the heavy concrete of the wall, and the inner steel plate of the wall increased by 8.12, 8.11, 0.31, and 0.30 °C, respectively. The tensile strain of the heavy concrete of the wall increased significantly by 52.64%, and the compressive strain of the concrete increased by 67.33%, whereas the stresses of the studs and steel plates increased by only 1.57% and 6.79%, respectively. These results show that the change in the temperature field greatly influences the stress and strain on the TPC structure. As measures for mitigating the development of this unfavorable situation of temperature stress concentration, the temperature operating range should be rationally controlled or the junction structure between the transfer and purge sub-chambers of the TPC optimized accordingly. The results of our study can provide basic data for a dynamic analysis of the TPC under conditions of combined earthquake and temperature loads.

Decontamination performance of a bioretention system using a simple sand-based filler proportioning method.

This study investigated the decontamination performance of a bioretention system using a sand-based filler constructed using sand and peat soil. The filler was constructed according to a simple proportioning method that considers water turnover time and organic content. Different inorganic constituents were added to the filler including zeolite, volcanic rock, coal slag, vermiculite and perlite to further improve the decontamination effect. Total suspended solids (TSS), total phosphorus (TP), ammonium nitrogen (NH4+-N), total nitrogen (TN) and chemical oxygen demand (COD) were measured in the influent and effluent. The results showed that: (1) the overall removal effect of the sand-based filler was satisfactory, indicating a certain feasibility and practicality of the method; (2) bioretention based on the sand-based filler had a better performance in removing TSS and TP with the removal rate both over 95%, and the addition of inorganic constituents to the filler was beneficial to TSS removal due to the effect of cumulative filtration capabilities of multiple materials, while phosphate was easily adsorbed by the positively charged particles of the peat soil; (3) the high removal rate of NH4+-N was due to adsorption and it could reach more than 80% by adding inorganic constituents with good adsorption such as zeolite vermiculite and perlite. Similarly, the addition of vermiculite and coal slag could increase the removal rate of COD by 15-25%. This research offers a novel alternative for guiding the selection and proportion of fillers in bioretention systems.

Efficacy and safety of acupoint injection therapy for allergic rhinitis: A protocol for systematic review and meta-analysis.

BACKGROUND: Allergic rhinitis (AR), characterized by nasal itching, sneezing, and congestion, is a common disorder of nose. In the United States, AR affects 10% to 20% of adults. The negative impact of the high prevalence of AR has caused a great economic burdens worldwide. Modern Western Medicine mainly treats AR with antihistamine drugs, glucocorticoids, allergic immunotherapy (AIT), but it seriously affects patients compliance because of its long course of treatment, high medical costs and side effect. And now, as an important mean of treating AR, acupoint injection has been widely used in clinics, and has achieved significant efficacy. METHODS AND ANALYSIS: The following databases will be searched for relevant information before July 2020: PubMed, Embase, Cochrane Library, Web of Science, and CNKI. MAJOR RESULTS: scores of Rhinitis Quality of Life (RQLQ), Rhinitis Total Symptom Scores (RTSS). Secondary results: levels of antigen-specific serum immunoglobulin E (IgE), total effective rate, adverse event. Data will be collected independently by 2 researchers, and the risk of bias in meta-analysis will be evaluated according to "Cochrane Handbook for Systematic Reviews of Interventions". All data analysis will be conducted using Review Manager V.5.3. and Stata V.12.0. RESULTS: The curative effect and safety of acupoint injection treatment for AR patients will be evaluated systematically. CONCLUSION: The systematic review of this study will summarize the currently published evidence of acupoint injection treatment for AR to further guide its promotion and application. ETHICS AND DISSEMINATION: The private information from individuals will not be published. This systematic review also will not involve endangering participant rights. Ethical approval is not required. The results may be published in a peer-reviewed journal or disseminated in relevant conferences.Open Science Framework (OSF) registration number: https://osf.io/fa9dq.