خيارات البحث
النتائج 181 - 190 من 3,189
Organobromine compound profiling in human adipose: Assessment of sources of bromophenol
2015
Gao, Shixiong | Wan, Yi | Zheng, Guomao | Luo, Kai | Kannan, Kurunthachalam | Giesy, John P. | Lam, Michael H.W. | Hu, Jianying
Bromophenols (BRPs) have been widely detected in human tissues, however, relative proportions from natural products and/or anthropogenic flame retardants are not clear. 21 polybrominated diphenyl ethers (PBDEs), 15 MeO/OH-PBDEs, and 10 BRPs were simultaneously quantified in adipose collected from people from New York City, USA. An in vitro assay utilizing human liver microsomes was performed for detected predominant organobromine. High concentrations of 2,4,6-triBRP and PBDEs were observed, and extremely low concentrations of naturally occurring MeO/OH-PBDEs were detected. Similar biotransformatioin rates of BRPs and MeO/OH-PBDEs indicated that the relative high concentration of 2,4,6-triBRP in humans was not of natural origin. Significant correlation observed between concentrations of 2,4,6-triBRP and BDE-209 suggested that the two chemicals may share a common source. Both 2,4,6-triBRP and BDE-209 were detected in commercial ABS resins, suggesting that plastic products made from ABS resins could be potential sources of co-exposure of the two compounds for humans.
اظهر المزيد [+] اقل [-]The impact of long term exposure to phthalic acid esters on reproduction in Chinese rare minnow (Gobiocypris rarus)
2015
Guo, Yongyong | Yang, Yuanjin | Gao, Yong | Wang, Xianfeng | Zhou, Bingsheng
The environmental risk of phthalic acid esters (PAEs) is of great concern. We investigated the reproductive impairment of di-(2-ethylhexyl)-phthalate (DEHP) on Chinese rare minnow, an endemic fish inhabiting the upper streams of the Yangtze River. Chinese rare minnow larvae were exposed to environmentally relevant concentrations of DEHP (0, 4.2, 13.3, and 40.8 μg/L) for 6 months. Plasma testosterone and 17β-estradiol levels decreased in females, accompanied by downregulation of cyp19a and cyp17 gene transcription in ovary. Increases in plasma testosterone concentration were observed in males, accompanied by downregulation of cyp19a gene transcription in testes. Hepatic VTG gene transcription was upregulated in males and females. Exposure to DEHP reduced egg production and inhibited oocyte maturation in females and retarded spermiation in males. Decreased egg protein content was measured in F1 embryos. These results indicate that long-term exposure to low concentrations of DEHP (13.3 μg/L) causes endocrine disruption and impairs fish reproduction.
اظهر المزيد [+] اقل [-]Predicting fecal indicator organism contamination in Oregon coastal streams
2015
Pettus, Paul | Foster, Eugene | Pan, Yangdong
In this study, we used publicly available GIS layers and statistical tree-based modeling (CART and Random Forest) to predict pathogen indicator counts at a regional scale using 88 spatially explicit landscape predictors and 6657 samples from non-estuarine streams in the Oregon Coast Range. A total of 532 frequently sampled sites were parsed down to 93 pathogen sampling sites to control for spatial and temporal biases. This model's 56.5% explanation of variance, was comparable to other regional models, while still including a large number of variables. Analysis showed the most important predictors on bacteria counts to be: forest and natural riparian zones, cattle related activities, and urban land uses. This research confirmed linkages to anthropogenic activities, with the research prediction mapping showing increased bacteria counts in agricultural and urban land use areas and lower counts with more natural riparian conditions.
اظهر المزيد [+] اقل [-]Prenatal nonylphenol exposure, oxidative and nitrative stress, and birth outcomes: A cohort study in Taiwan
2015
Wang, Pei-Wei | Chen, Mei-Lien | Huang, Li-Wei | Yang, Wenni | Wu, Kuen-Yuh | Huang, Yu-Fang
Data concerning the effects of prenatal exposures to nonylphenol (NP) and oxidative stress on neonatal birth outcomes from human studies are limited. A total of 146 pregnant women were studied (1) to investigate the association between prenatal NP exposure and maternal oxidative/nitrative stress biomarkers of DNA damage (8-hydroxy-2’-deoxyguanosine (8-OHdG), 8-nitroguanine (8-NO2Gua)) and lipid peroxidation (8-iso-prostaglandin F2α (8-isoPF2α), 4-hydroxy-2-nonenal-mercapturic acid (HNE-MA)) and (2) to explore the associations among oxidative stress biomarkers, NP exposure, and neonatal birth outcomes, including gestational age, birth weight, length, Ponderal index, and head and chest circumferences. NP significantly increased the 8-OHdG and 8-NO2Gua levels. All infants born to mothers with urinary 8-OHdG levels above the median exhibited a significantly shorter gestational duration (Badjusted = −4.72 days; 95% CI: −8.08 to −1.36 days). No clear association was found between NP levels and birth outcomes. Prenatal 8-OHdG levels might be a novel biomarker for monitoring fetal health related to NP exposure.
اظهر المزيد [+] اقل [-]A distributed network of low-cost continuous reading sensors to measure spatiotemporal variations of PM2.5 in Xi'an, China
2015
Gao, Meiling | Cao, Junji | Seto, Edmund
Fine particulate matter (PM2.5) is a growing public health concern especially in industrializing countries but existing monitoring networks are unable to properly characterize human exposures due to low resolution spatiotemporal data. Low-cost portable monitors can supplement existing networks in both developed and industrializing regions to increase density of sites and data. This study tests the performance of a low-cost sensor in high concentration urban environments. Seven Portable University of Washington Particle (PUWP) monitors were calibrated with optical and gravimetric PM2.5 reference monitors in Xi'an, China in December 2013. Pairwise correlations between the raw PUWP and the reference monitors were high (R2 = 0.86–0.89). PUWP monitors were also simultaneously deployed at eight sites across Xi'an alongside gravimetric PM2.5 monitors (R2 = 0.53). The PUWP monitors were able to identify the High-technology Zone site as a potential PM2.5 hotspot with sustained high concentrations compared to the city average throughout the day.
اظهر المزيد [+] اقل [-]Induction of c-Jun by air particulate matter (PM10) of Mexico city: Participation of polycyclic aromatic hydrocarbons
2015
Salcido-Neyoy, Martha Estela | Sánchez-Pérez, Yesennia | Osornio-Vargas, Alvaro Román | Gonsebatt, Maria Eugenia | Meléndez-Zajgla, Jorge | Morales-Bárcenas, Rocío | Petrosyan, Pavel | Molina-Servin, Edith Danny | Vega, Elizabeth | Manzano-León, Natalia | García-Cuellar, Claudia M.
The carcinogenic potential of urban particulate matter (PM) has been partly attributed to polycyclic aromatic hydrocarbons (PAHs) content, which activates the aryl hydrocarbon receptor (AhR). Here we report the effect of PM with an aerodynamic size of 10 μm (PM10) on the induction of AhR pathway in A549 cells, evaluating its downstream targets CYP1B1, IL-6, IL-8 and c-Jun. Significant increases in CYP1B1 protein and enzyme activity; IL-6 and IL-8 secretion and c-Jun protein were found in response to PM10. The formation of PAH-DNA adducts was also detected. The involvement of AhR pathway was confirmed with Resveratrol as AhR antagonist, which reversed CYP1B1 and c-Jun induction. Nevertheless, in IL-6 and IL-8 secretion, the Resveratrol was ineffective, suggesting an effect independent of this pathway. Considering the role of c-Jun in oncogenesis, its induction by PM may be contributing to its carcinogenic potential through induction of AhR pathway by PAHs present in PM10.
اظهر المزيد [+] اقل [-]What does impacted look like? High diversity and abundance of epibiota in modified estuaries
2015
Clark, Graeme F. | Kelaher, Brendan P. | Dafforn, Katherine A. | Coleman, Melinda A. | Knott, Nathan A. | Marzinelli, Ezequiel M. | Johnston, Emma L.
Ecosystems modified by human activities are generally predicted to be biologically impoverished. However, much pollution impact theory stems from laboratory or small-scale field studies, and few studies replicate at the level of estuary. Furthermore, assessments are often based on sediment contamination and infauna, and impacts to epibiota (sessile invertebrates and algae) are seldom considered. We surveyed epibiota in six estuaries in south-east Australia. Half the estuaries were relatively pristine, and half were subject to internationally high levels of contamination, urbanisation, and industrialisation. Contrary to predictions, epibiota in modified estuaries had greater coverage and were similarly diverse as those in unmodified estuaries. Change in epibiota community structure was linearly correlated with sediment-bound copper, and the tubeworm Hydroides elegans showed a strong positive correlation with sediment metals. Stressors such as metal contamination can reduce biodiversity and productivity, but others such as nutrient enrichment and resource provision may obscure signals of impact.
اظهر المزيد [+] اقل [-]Factors controlling peat chemistry and vegetation composition in Sudbury peatlands after 30 years of pollution emission reductions
2015
Barrett, Sophie E. | Watmough, Shaun A.
The objective of this research was to assess factors controlling peat and plant chemistry, and vegetation composition in 18 peatlands surrounding Sudbury after more than 30 years of large (>95%) pollution emission reductions. Sites closer to the main Copper Cliff smelter had more humified peat and the surface horizons were greatly enriched in copper (Cu) and nickel (Ni). Copper and Ni concentrations in peat were significantly correlated with that in the plant tissue of Chamaedaphne calyculata. The pH of peat was the strongest determining factor for species richness, diversity, and community composition, although percent vascular plant cover was strongly negatively correlated with surface Cu and Ni concentrations in peat. Sphagnum frequency was also negatively related to peat Cu and Ni concentrations indicating sites close to Copper Cliff smelter remain adversely impacted by industrial activities.
اظهر المزيد [+] اقل [-]Complexation of silver and dissolved organic matter in soil water extracts
2015
Settimio, Lara | McLaughlin, Mike J. | Kirby, Jason K. | Langdon, Kate A. | Janik, Les | Smith, Scott
An important aspect of the behaviour and fate of silver (Ag) in soils is the interaction with dissolved organic matter (DOM). The complexation and strength of binding of Ag+ with DOM in soil water extracts was examined and modelled based on a range of chemical and quality DOM measurements. Silver ion binding measured by addition of the 110mAg radioisotope in addition to a cation exchange resin technique were used to determine strongly complexed Ag in solutions. Silver was found to be up to 70% strongly complexed. The variability in Ag+ binding by DOM across different soils was closely related (R2 = 0.8) to the mid-infrared spectra of these extracts. The affinity of Ag+ for DOM was stronger in solutions containing a greater content of humic and aromatic structures. The ability of Ag+ to complex with DOM could result in increased mobilisation of this metal in the soil environment.
اظهر المزيد [+] اقل [-]Enhanced photosynthetic capacity and antioxidant potential mediate brassinosteriod-induced phenanthrene stress tolerance in tomato
2015
Ahammed, Golam Jalal | Li, Xin | Xia, Xiao-Jian | Shi, Kai | Zhou, Yan-Hong | Yu, Jing-Quan
Photosynthesis, the basal manufacturing process in the earth is habitually restricted by airborne micropollutants such as phenanthrene (PHE). Here, we show that 24-epibrassinolide (EBR), a bioactive plant steroid is able to keep higher photosynthetic capacity consistently for a long period under a shoot-imposed PHE stress in tomato. EBR-promoted photosynthetic capacity and efficiency eventually resulted in a 37.5% increase of biomass under PHE stress. As primary response, transcripts of antioxidant genes were remarkably induced by EBR in PHE-treated plants. Activities of antioxidant and detoxification enzymes were also enhanced by EBR. Notably, EBR-induced higher antioxidant potential was associated with reduced levels of H2O2 and O2—, resulting in a 32.7% decrease of content of malondialdehyde in the end of experiment and relatively healthy chloroplast ultrastructure in EBR + PHE treatment compared with PHE alone. These results indicate that EBR alleviates shoot-imposed PHE phytotoxicity by maintaining a consistently higher photosynthetic capacity and antioxidant potential in tomato.
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