A rapid, reliable, and sensitive method was developed for the determination of ten tranquilizers in swine urine. Sample preparation was based on solid-phase extraction, which combined isolation of the compounds and sample cleanup in a single step. Separation was performed on a reversed phase C18 column by gradient elution with a chromatographic run time of seven minutes, consisting of 0.1% formic acid in water and acetonitrile as the mobile phase. Multiple reaction monitoring in positive mode was applied for data acquisition. Matrix-matched calibration was used for quantification and good linearity was obtained with coefficients of determination higher than 0.99. The average recoveries of fortified samples at concentrations between 0.05 and 10 µg/L ranged from 85% to 106% with interday relative standard deviations of less than 13% in all cases. The limits of detection and limits of quantification obtained for tranquilizers in the urine were in the ranges of 0.03⁻0.1 µg/L and 0.05⁻0.25 µg/L, respectively. The applicability of the proposed method was demonstrated by analyzing real samples; diazepam was detected at concentrations between 0.3 and 0.6 μg/L.
: The current study was to elucidate the molecular defect in a 32-year-old Chinese woman with heavy menorrhagia and delayed wound healing. The F11 gene was amplified by PCR and screened for mutations. Then identified mutations were analyzed by in-silico programs and molecular modeling analysis. This woman was found to have severely low levels of factor XI (FXI) (FXI:C: 2.0%; FXI:Ag: 5.4%) by surgical screening. Further DNA sequencing of F11 reveled a novel mutation (p.Ser295Ile) in the Ap4 domain and an already known mutation (p.Trp228stop) in the Ap3 domain. Pedigree analysis showed that the new mutation was inherited from her father (FXI:C: 41%), whereas the other was inherited from her mother (FXI:C: 62%). Modeling analysis indicated Ser295Ile mutation probably determining important structural changes in the protein folding. Both of the heterozygous mutation contribute to the severe FXI deficiency by interfering with correct assembly of the region.
The optrA gene, which confers transferable resistance to oxazolidinones and phenicols, is defined as an ATP-binding cassette (ABC) transporter but lacks transmembrane domains. The resistance mechanism of optrA and whether it involves antibiotic efflux or ribosomal protection remain unclear. In this study, we determined the MIC values of all bacterial strains by broth microdilution, and used ultra-high performance liquid chromatography-tandem quadrupole mass spectrometry to quantitatively determine the intracellular concentrations of linezolid and florfenicol in Enterococcus faecalis and Staphylococcus aureus. Linezolid and florfenicol both accumulated in susceptible strains and optrA-carrying strains of E. faecalis and S. aureus. No significant differences were observed in the patterns of drug accumulation among E. faecalis JH2-2, E. faecalis JH2-2/pAM401, and E. faecalis JH2-2/pAM401+optrA, but also among S. aureus RN4220, S. aureus RN4220/pAM401, and S. aureus RN4220/pAM401+optrA. ANOVA scores also suggested similar accumulation conditions of the two target compounds in susceptible strains and optrA-carrying strains. Based on our findings, the mechanism of optrA-mediated resistance to oxazolidinones and phenicols obviously does not involve active efflux and the OptrA protein does not confer resistance via efflux like other ABC transporters.
The emergence and worldwide dissemination of plasmid-mediated colistin resistance gene mcr-1 has attracted global attention. The MCR-1 enzyme mediated colistin resistance by catalyzing phosphoethanolamine (PEA) transfer onto bacterial lipid A. However, the interaction partners of MCR-1 located in membrane protein in E. coli are unknown. Co-immunoprecipitation (Co-IP) and Mass Spectrometry were performed to define the interacting proteins of MCR-1. A total of three different anti-MCR-1 monoclonal antibody (mAbs) were prepared and 3G4 mAb was selected as the bait protein by compared their suitability for Co-IP. We identified 53, 13, and 14 interacting proteins in E. coli BL21 (DE3) (pET28a- mcr-1 ), E. coli BL21 (DE3) (pET28a- mcr-1-200 ), and E. coli DH5α (pUC19- mcr-1 ), respectively. Six proteins, including the stress response proteins DnaK (chaperone protein) and SspB (stringent starvation protein B), the transcriptional regulation protein H-NS, and ribosomal proteins (RpsE, RpsJ, and RpsP) were identified in all these three strains. These MCR-1-interacting proteins were mainly involved in ribosome and RNA degradation, suggesting that MCR-1 influences the protein biosynthesis through the interaction with ribosomal protein. Multidrug efflux pump AcrA and TolC were important interacting membrane proteins of MCR-1 referred to drug efflux during the PEA modification of the bacterial cell membrane. Overall, we firstly identified the functional interactome profile of MCR-1 in E. coli and discovered that two-component AcrA-TolC multidrug efflux pump was involved in mcr-1 -mediated colistin resistance.
A reliable monitoring system is significant to guarantee the equilibrium operation of cloud services. Based on the monitoring system, a novel state warning scheme using fuzzy logic is proposed in this paper. The improved exponential smoothing algorithm is applied to predict the reference value and calculate the dynamic threshold interval. Then, the service overall abnormal degree from each monitoring indicator can be obtained by designing and applying the fuzzy logic. Therefore, the system can respond quickly based on the evaluated alarm level. Finally, several experiments are conducted to evaluate the performances of the proposed warning scheme.
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