PCR assays have proved useful for detecting and characterizing Shiga toxin-producing Escherichia coli (STEC). Recent advances in PCR technology have facilitated the development of real-time fluorescence PCR assays with greatly reduced amplification times and improved methods for the detection of amplified target sequences. We developed and evaluated two such assays for the LightCycler instrument: one that simultaneously detects the genes for Shiga toxins 1 and 2 (stx 1 and stx 2 ) and another that simultaneously detects the genes for intimin (eae) and enterohemolysin (E-hly). Amplification and sequence-specific detection of the two target genes were completed within 60 min. Findings from the testing of 431 STEC isolates of human and animal origin, 73 isolates of E. coli negative for stx genes, and 118 isolates of other bacterial species with the LightCycler PCR (LC-PCR) assays were compared with those obtained by conventional block cycler PCR analysis. The sensitivities and specificities of the LC-PCR assays were each 100% for the stx 1 , eae, and E-hly genes and 96 and 100%, respectively, for the stx 2 gene. No stx 2 genes were detected from 10 stx 2f -positive isolates because of significant nucleotide differences in their primer annealing regions. Melting curve analyses of the amplified Shiga toxin genes revealed sequence variation within each of the tested genes that correlated with described and novel gene variants. The performance characteristics of the LC-PCR assays, such as their speed, detection method, and the potential subtyping information available from melting curve analyses, make them attractive alternatives to block cycler PCR assays for detecting and characterizing STEC strains.
The Nanping No. 31 granitic pegmatite, a highly evolved spodumene-type pegmatite in the Nanping pegmatite district, southeastern China, can be divided into five internal zones from the border inward: zones I-III as the outer zones and zones IV-V as the inner zones. It is strongly mineralized with Nb-Ta-Sn oxide minerals. We investigated these minerals by using back-scattered electron (BSE) imaging and quantitative electron-microprobe analyses (EMPA) to characterize their complex internal textures. The primary Nb-Ta oxide minerals show a sequence from columbite-(Fe) (zone I) through tantalite-(Fe) (zone II) to tantalite-(Mn) (zone III), but distinctly become columbite + wodginite in zone IV and, rarely, columbite in the zone V. Microscopic tapiolite-(Fe) is identified as a product of exsolution in cassiterite from the zones II-III, whereas complex associations of wodginite, columbite-tantalite and tapiolite-(Fe) are characteristic of cassiterite in zone IV. The classic variation of the columbite-group minerals from the zones I to III seems to result from the greater stability of tantalite than columbite components during fractional crystallization of the melt. However, decreasing values of Ta/(Nb + Ta) in columbite-group minerals in the inner zones are more probably compensated by crystallization of abundant primary wodginite-group minerals, controlled by the f(O 2 ) of the magma. Columbite-group minerals commonly exhibit zoning, but complex and multiple-generation phenomena are notable in columbite-tantalite crystals from zones IV-V. In the latter case, later generations of columbite-tantalite overgrow or crosscut the earlier ones. Irregular patterns of zoning are linked to the activity of hydrothermal fluids at the late stages of pegmatite evolution. The high mobility of Ta in such fluids is supported by the development of veinlets of tantalite. They cross-cut first the earlier-formed columbite + wodginite aggregates, and later fill brittle-deformation-induced fissures in the columbite, forming a network texture. The complex internal textures of Nb-Ta-Sn oxide minerals from the zones IV-V indicate a distinctly fluid-rich environment at the late stage of crystallization of the Nanping No. 31 pegmatite.Keywords: Nb-Ta oxide minerals, cassiterite, columbite-tantalite, tapiolite-(Fe), wodginite, Ta-rich fluid, the Nanping No. 31 pegmatite, China.sOmmaiRe La pegmatite granititique dite Nanping No. 31, fortement évoluée et cristallisant le spodumène, affleure dans le district pegmatitique de Nanping, dans le sud-est de la Chine; nous distinguons cinq zones internes allant de la bordure vers le centre: les zones I-III sont externes, et les zones IV-V sont internes. La pegmatite est fortement minéralisée en oxydes de Nb-Ta-Sn. Nous avons étudié ces minéraux et leurs textures internes complexes au moyen d'images générées par les électrons rétrodiffusés et par analyses quantitatives effectuées avec une microsonde électronique. Les oxydes de Nb-Ta primaires définissent une séquence allant de columbite-(Fe) (zone I...
ObjectivesRelevant guidelines and consensuses for COVID-19 contain recommendations aimed at optimising the management in paediatric wards. The goal of this study was to determine the quality of those recommendations and provide suggestions to hospital managers for the adjustment of existing hospital prevention and control strategies, and also to offer recommendations for further research.DesignA rapid review of the guidelines and consensuses for the management in paediatric wards facing COVID-19.MethodsPubMed, EMBASE, the Cochrane Library, UpToDate, China National Knowledge Infrastructure, the Wanfang database and relevant websites such as medlive.cn, dxy.cn, the National Health and Health Commission and the China Center for Disease Control and Prevention were systematically searched through late May 2020. The Appraisal of Guidelines for Research and Evaluation II (AGREE II) tool was then used to assess the quality of the selected articles and summarise the relevant evidence concerning management in paediatric wards.ResultsA total of 35 articles were included, composed of 3 consensus guidelines, 25 expert consensuses and 7 expert opinions. Of the 35 papers, 24 were from China, 2 from the USA, 1 from Spain, 1 from Brazil, 1 from Saudi Arabia and 6 from multinational cooperative studies. Scores for the six domains of the AGREE II tool (scope and purpose, stakeholder involvement, rigour of development, clarity of presentation, applicability and editorial independence) were 98.57%, 53.57%, 17.92%, 69.62%, 26.96% and 50.35%, respectively. Recommendations for nosocomial infection and control, human resource management as well as management of paediatric patients and their families were summarised.ConclusionsDue to the outbreak of COVID-19, the quality of rapid guidelines and consensuses for the management in paediatric wards affected by COVID-19 is unsatisfactory. In the future, it will be necessary to develop more high-quality guidelines or consensuses for the management in paediatric wards to deal with nosocomial outbreaks in order to fully prepare for emergency medical and health problems.
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