| 1. |
- 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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| 2. |
- Li, Li, et al.
(författare)
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Characterization of residential household dust from Shanghai by particle size and analysis of organophosphorus flame retardants and metals
- 2019
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Ingår i: Environmental Sciences Europe. - : Springer. - 2190-4707 .- 2190-4715. ; 31:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Physical and biological properties of dust particles might affect the availability and distribution of chemicals associated to indoor dust; however it has not been adequately examined. In this study, household dust from Shanghai was fractionated into five particle sizes and size distribution, morphology, surface area, organic matter, microorganisms, elemental composition, metals and organophosphorus flame retardants (OPFRs) compositions were characterized. Also, household dust samples from Stockholm that has previously been characterized were included in the analysis of OPFRs for comparison.Results: The respirable fraction had a yield of 3.3% in mass percentage, with a particle size of 2.22 +/- 2.04 mu m. As expected, both metals and OPFRs concentrations increased with decreased particle size. Al and Fe dominated (66-87%) followed by the concentrations of Zn (5-14%) and Ga (1.8-5%) of the sum of 16 metals in the dust. The concentrations of OPFRs in Shanghai dust ranged from 5.34 to 13.7 mu g/g (median: 7.21 mu g/g), compared to household dust from Stockholm that ranged from 16.0 to 28.3 mu g/g (median: 26.6 mu g/g). Tris(2-chloroisopropyl) phosphate (TCIPP) and tris(2-chloroethyl) phosphate (TCEP) dominated in Shanghai dust samples while tris(2-butoxyethyl) phosphate (TBOEP) dominated in dust from Stockholm homes.Conclusion: The results showed that mass percentage for each particle size fraction was not evenly distributed. Furthermore, the particle-bound microorganisms and OPFRs increased with decreased particle size, whereas metals had the highest concentrations at specific dust sizes. Therefore, it is essential to select the proper particle size in order to assess any specific human exposure study to indoor pollutants.
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| 3. |
- Niu, Dong, et al.
(författare)
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Novel brominated flame retardants in house dust from Shanghai, China : levels, temporal variation, and human exposure
- 2019
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Ingår i: Environmental Sciences Europe. - : Springer London. - 2190-4707 .- 2190-4715. ; 31:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Novel brominated flame retardants (NBFRs) have been increasingly used as alternatives to legacy BFRs (e.g., PBDEs and HBCDs) in consumer products, but are liable to emigrate and contaminate indoor dust. In this study, a total of 154 house dust samples including floor dust (FD) and elevated surface dust (ESD) were collected in the biggest metropolitan area (Shanghai) of East China in 2016. Limited information about temporal variation of NBFRs indoors is available, while the period of sampling is influential in human exposure estimates. Levels, temporal variation, and human exposure of seven target NBFRs such as decabromodiphenylethane (DBDPE), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), 2-ethylhexyl 2,3,4,5-tetrabromobenzoate (EHTBB), and bis(2-ethylhexyl) tetrabromophthalate (BEHTEBP) were investigated in indoor house dust.Results: Concentrations of Sigma(7)NBFRs ranged from 19.11 to 3099ng/g with a geomean of 295.1ng/g in FD, and from 34.74 to 404.6ng/g with a geomean of 117.9ng/g in ESD. The geomeans of DBDPE were 219.6ng/g in FD and 76.89ng/g in ESD, accounting for 90.5% and 80.5% of Sigma(7)NBFRs. Levels of EHTBB, BTBPE, and DBDPE in FD exceeded significantly those in ESD. The temporal variation in Sigma(7)NBFRs in FD was ranked as summer>winter>autumn>spring. The daily exposure doses (DEDs) of Sigma(7)NBFRs via dust ingestion decreased as: infants>toddlers>children>teenagers>adults. Infants showed the highest DED in FD, 9.1ng/kg bw/day.Conclusions: DBDPE clearly dominated the NBFRs in both FD and ESD, but the concentrations of DBDPE in this study were generally moderate compared with the other international studies. Dust ingestion was the major pathway of human exposure to NBFRs indoors. About eightfold difference in exposure estimates between infants and adults showed that infants faced elevated exposure risks in FD. This study highlighted the necessity to estimate human exposure of NBFRs for different age groups using FD and ESD, respectively.
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| 4. |
- Du, Xinyu, et al.
(författare)
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Distribution, behavior, and risk assessment of chlorinated paraffins in paddy plants throughout whole growth cycle
- 2022
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Ingår i: Environment International. - : Elsevier BV. - 0160-4120 .- 1873-6750. ; 167
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Tidskriftsartikel (refereegranskat)abstract
- Paddy plants provide staple food for 3 billion people worldwide. This study explores the environmental fate and behavior of a high-volume production emerging contaminants chlorinated paraffins (CPs) in the paddy ecosystem. Very-short-, short-, medium-, and long-chain CPs (vSCCPs, SCCPs, MCCPs, and LCCPs, respectively) were analyzed in specific tissue of paddy plants at four main growth stages and soils from the Yangtze River Delta, China throughout a full rice growing season. The total CP concentrations in the paddy roots, stalks, leaves, panicles, hulls, rice, and soils ranged from 181 to 1.74 × 103, 21.7–383, 19.6–585, 108–332, 245–470, 59.6–130, and 99.6–400 ng/g dry weight, respectively. The distribution profile indicated the translocation of SCCPs and MCCPs from soils to paddy tissue, highlighting their elevated bioaccumulative potential. The evolution of CP level/mass/pattern during the whole growth cycle suggested atmospheric CPs deposition on leaves and hulls, as well as stalk-rice transfer. CSOIL plant uptake model well predicted the level, distribution pattern, and bioconcentration factors (BCFs) of SCCPs and MCCPs in paddy shoot and recognized the soil-air-shoot pathway as the major contributor. Moreover, risk evaluation indicated that MCCPs intake and subsequent risks dominated the total exposure to CPs via rice ingestion. This is the first report on the occurrence, fate and risk assessment of all CPs classes in paddy ecosystems, and the results underline the potential health effects caused by the in-use MCCPs via rice ingestion.
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| 5. |
- Du, Xinyu, et al.
(författare)
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Evaluating oral and inhalation bioaccessibility of indoor dust-borne short- and median-chain chlorinated paraffins using in vitro Tenax-assisted physiologically based method
- 2021
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Ingår i: Journal of Hazardous Materials. - : Elsevier. - 0304-3894 .- 1873-3336. ; 402
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Tidskriftsartikel (refereegranskat)abstract
- Though ingestion and inhalation of dust have been suggested as important exposure routes contributing chlorinated paraffins (CPs) build-up in humans, the bioaccessibility of dust-borne CPs in the organ environment has not been well-studied, which may hinder an accurate estimation of exposure risks. In this study, the ingestion and inhalation bioaccessibility of dust-borne shortand median-chain CPs (SCCPs and MCCPs) was assessed using (colon-extended) physiologically based extraction test with the addition of Tenax. The ingestion bioaccessibility of SCCPs 51.5 %Cl, SCCPs 63 %Cl, MCCPs 42 %Cl, and MCCPs 57 %Cl was in ranges of 21.1-44.0 %, 11.7-45.8 %, 21.9-36.6 %, and 7.9-32.9 %, respectively. Multiple linear regression analysis demonstrated statistically significant associations of ingestion bioaccessibility with carbon chain length and chlorine substitution. The ingestion bioaccessibility of CPs also increased with co-existence of carbohydrate/protein. The inhalation bioaccessibility of SCCPs (16.7-38.7 % in artificial lysosomal fluid and 15.5-34.1 % in modified Gamble solution) was significantly higher than MCCPs (< 5 %), and varied with dust particle size/total organic carbon content. Our study indicates that modest bioaccessible fractions of CPs in dust should be taken into account to refine the estimation of human exposure, and their bioaccessibility may be affected by CP molecular size, nutritional content and dust property.
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| 6. |
- Li, Qian, et al.
(författare)
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Multiple biomarker responses in caged benthic gastropods Bellamya aeruginosa after in situ exposure to Taihu Lake in China
- 2018
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Ingår i: Environmental Sciences Europe. - : Springer Science and Business Media LLC. - 2190-4707 .- 2190-4715. ; 30
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Tidskriftsartikel (refereegranskat)abstract
- Background: Freshwater sediments have been recognized as a long-term sink and potential source for environmental pollutants released into the aquatic ecosystems. In this study, the sediment quality of Taihu Lake, which is susceptible to anthropogenic contamination, was assessed by a combination of chemical analytical and biological end points. Specifically, the snail Bellamya aeruginosa was caged in situ at two locations representing different pollution levels for different exposure times (7, 14 and 21 days). At each of these time points, biochemical parameters, i.e., phase I biotransformation enzymes ethoxyresorufin-O-deethylase (EROD), the antioxidant enzymes superoxide dismutase and catalase, reactive oxygen species, protein carbonyl content and lipid peroxidation, were evaluated in the hepato-pancreas of snails. In addition, surface sediments were collected for analysis of contaminants of concern, including inorganic pollutants, organochlorine pesticides, polychlorinated biphenyls and polybrominated diphenyl ethers.Results: Chemical analyses revealed that sediments from Taihu Lake were contaminated with trace elements and organic pollutants. Concentrations of trace elements (Cu, Ni and As) and organochlorinated pesticides (4,4'-DDE) exceeded their corresponding threshold effect level according to the sediment quality assessment values for freshwater ecosystems in Canada, indicating that adverse biological effects may occur. All biomarkers, except EROD activity, were induced in snails during all exposure times. The integrated biomarker response index (IBR) indicated that during the initial exposure phase (7 days), B. aeruginosa were subjected to significant environmental stress, which diminished during later sampling time points.Conclusions: Results showed that IBR correlated well with the levels of environmental contaminants, demonstrating the applicability of this biomonitoring approach to complex environmental exposure scenarios.
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| 7. |
- Lv, Yaodong, et al.
(författare)
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Association of plaque characteristics with long-term stroke recurrence in patients with intracranial atherosclerotic disease : a 3D high-resolution MRI-based cohort study
- 2023
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Ingår i: European Radiology. - 0938-7994 .- 1432-1084.
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Tidskriftsartikel (refereegranskat)abstract
- Objectives To evaluate the predictive ability of plaque characteristics for long-term stroke recurrence among patients with symptomatic intracranial atherosclerotic disease (ICAD).Methods This cohort study included 132 patients with acute ischemic stroke (AIS) attributed to ICAD who were recruited between July 2017 and December 2020 and followed until stroke recurrence or December 2021. Plaque surface irregularity, degree of stenosis, plaque burden, remodeling ratio, enhancement ratio, and intraplaque hemorrhage were assessed with 3-dimensional high-resolution magnetic resonance vessel wall imaging (3D HR-MRI). Data were analyzed using Cox models, receiver operating characteristic (ROC) curves, and Kaplan-Meier survival analysis.Results Of the 132 patients, during a median follow-up of 2.8 years, stroke recurrence occurred in 35 patients. The multivariable-adjusted hazard ratio (95% confidence interval) of stroke recurrence was 3.15 (1.34-7.42) per 10% increase in plaque burden and 2.17 (1.27-3.70) for enhancement ratio. The area under the curve (AUC) to predict stroke recurrence was 0.725 (95% CI 0.629-0.822) for plaque burden, 0.692 (95% CI 0.593-0.792) for enhancement ratio, and only 0.595 (95% CI 0.492-0.699) for the Essen stroke risk score. The Kaplan-Meier survival analysis further demonstrated significant differences in survival of free recurrent stroke between patients with plaque burden or enhancement ratio below and above the optimum cut-offs (both p < 0.001).Conclusion Higher plaque burden and enhancement ratio are independent risk factors for long-term stroke recurrence among patients with symptomatic ICAD, and valuable imaging markers for predicting and stratifying risk of stroke recurrence.
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