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- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 3. |
- Sun, Jing, et al.
(författare)
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Changes in patterns of antibiotic use in Chinese public hospitals (2005-2012) and a benchmark comparison with Sweden in 2012
- 2015
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Ingår i: JOURNAL OF GLOBAL ANTIMICROBIAL RESISTANCE. - : Elsevier BV. - 2213-7165. ; 3:2, s. 95-102
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Tidskriftsartikel (refereegranskat)abstract
- Changes in patterns of antibiotic use in Chinese hospitals before and after intensive nationwide interventions are reported and compared with Chinese national targets and antibiotic use in Swedish hospitals. Chinese data were collected quarterly and yearly from selected patient prescriptions/medical records and medicines inventory control systems from 15 hospitals (2005-2012). Swedish data were extracted from a 2010-point prevalence survey and 2009-2012 sales data from seven university hospitals. An interrupted time series with segmented regression analysis was used to measure changes in patterns of antibiotic use in Chinese hospitals before and after the interventions. Following the 2011 interventions, significant reductions in antibiotic use in Chinese hospitals were seen: the proportion of prescriptions with antibiotics decreased 4.7% (P=0.03) and the proportion of medical records with antibiotic prescription decreased 73% (P=0.04). The proportions of prescriptions and medical records with antibiotics in Chinese hospitals in 2012 were 10% and 50%, respectively, and remained much higher than Swedish hospitals (1.1% in DDD for outpatients and 34% in number of patients for inpatients). Inpatient consumption in Chinese hospitals dropped significantly from 910 DDD/1000 inpatient days in 2008 to 473 in 2012 (588 in Swedish hospitals). Antibiotics are being used less frequently in Chinese hospitals, broad-spectrum antibiotics are still preferred, and overall usage is higher than Sweden. A significant reduction in overall inpatient antibiotic consumption was observed after the interventions. It is not possible to identify whether the-changes have resulted in less inappropriate antibiotic use. Further studies are needed.
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- Wu, Lele, et al.
(författare)
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Organic matter composition and stability in estuarine wetlands depending on soil salinity
- 2024
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Ingår i: Science of the Total Environment. - 0048-9697 .- 1879-1026. ; 945
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Tidskriftsartikel (refereegranskat)abstract
- Coastal wetlands are key players in mitigating global climate change by sequestering soil organic matter. Soil organic matter consists of less stable particulate organic matter (POM) and more stable mineral-associated organic matter (MAOM). The distribution and drivers of MAOM and POM in coastal wetlands have received little attention, despite the processes and mechanisms differ from that in the upland soils. We explored the distribution of POM and MAOM, their contributions to SOM, and the controlling factors along a salinity gradient in an estuarine wetland. In the estuarine wetland, POM C and N were influenced by soil depth and vegetation type, whereas MAOM C and N were influenced only by vegetation type. In the estuarine wetland, SOM was predominantly in the form of MAOM (> 70 %) and increased with salinity (70 %–76 %), leading to long-term C sequestration. Both POM and MAOM increased with SOM, and the increase rate of POM was higher than that of MAOM. Aboveground plant biomass decreased with increasing salinity, resulted in a decrease in POM C (46 %–81 %) and N (52 %–82 %) pools. As the mineral amount and activity, and microbial biomass decreased, the MAOM C (2.5 %–64 %) and N pool (8.6 %–59 %) decreased with salinity. When evaluating POM, the most influential factors were microbial biomass carbon (MBC) and dissolved organic carbon (DOC). Key parameters, including MBC, DOC, soil salinity, soil water content, aboveground plant biomass, mineral content and activity, and bulk density, were identified as influencing factors for both MAOM abundance. Soil water content not only directly controlled MAOM, but together with salinity also indirectly regulated POM and MAOM by controlling microbial biomass and aboveground plant biomass. Our findings have important implications for improving the accumulation and increased stability of soil organic matter in coastal wetlands, considering the global sea level rise and increased frequency of inundation.
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