Zhang J.J.Y.,HECSB |
Sun L.,HECSB |
Barrett O.,University of Calgary |
Bertazzon S.,University of Calgary |
And 2 more authors.
Atmospheric Environment | Year: 2015
Airborne particulate matter has been associated with cardiovascular and respiratory morbidity and mortality, and there is evidence that metals may contribute to these adverse health effects. However, there are few tools for assessing exposure to airborne metals. Land-use regression modeling has been widely used to estimate exposure to gaseous pollutants. This study developed seasonal land-use regression (LUR) models to characterize the spatial distribution of trace metals and other elements associated with airborne particulate matter in Calgary, Alberta.Two-week integrated measurements of particulate matter with <1.0μm in aerodynamic diameter (PM1.0) were collected in the City of Calgary at 25 sites in August 2010 and 29 sites in January 2011. PM1.0 filters were analyzed using inductively-coupled plasma mass spectrometry. Industrial sources were obtained through the National Pollutant Release Inventory and their locations verified using Google Maps. Traffic volume data were obtained from the City of Calgary and zoning data were obtained from Desktop Mapping Technologies Incorporated. Seasonal wind direction was incorporated using wind rose shapes produced by Wind Rose PRO3, and predictor variables were generated using ArcMap-10.1. Summer and winter LUR models for 30 PM1.0 components were developed using SAS 9.2.We observed significant intra-urban gradients for metals associated with airborne particulate matter in Calgary, Alberta. LUR models explained a high proportion of the spatial variability in those PM1.0 components. Summer models performed slightly better than winter models. However, 24 of the 30 PM1.0 related elements had models that were either good (R20.70) or acceptable (R20.50) in both seasons. Industrial point-sources were the most influential predictor for the majority of PM1.0 components. Industrial and commercial zoning were also significant predictors, while traffic indicators and population density had a modest but significant contribution for most elements. Variables incorporating wind direction were also significant predictors. These findings contrast with LUR models for PM and gaseous pollutants in which traffic indicators are typically the most important predictors of ambient concentrations.These results suggest that airborne PM components vary spatially with the distribution of local industrial sources and that LUR modeling can be used to predict local concentrations of these airborne elements. These models will support future health studies examining the impact of PM components including metals. © 2015 .
Padhi B.K.,HECSB |
Rosales M.,HECSB |
NeuroToxicology | Year: 2015
Early life exposure to environmental chemicals can interfere with myelin formation in the developing brain, leading to neurological disorders. The Proteolipid Protein 1 (Plp1), Myelin Basic Protein (Mbp) and 2',3'- Cyclic Nucleotide 3'. Phosphodiesterase (Cnp) genes expressed in oligodendrocytes and involved in myelination processes can be useful biomarkers of potential developmental neurotoxicity. In an earlier study, we concluded that the reduction in the expression levels of Mbp splice variants in juvenile rat cerebellum following perinatal methylmercury (MeHg) exposure were compatible with an overall reduction of mature oligodendrocytes population. This observation prompted us to analyze the expression of Plp1 and Cnp in developing rat cerebellum to further confirm and investigate the toxic effects of MeHg on vulnerable oligodendrocytes. Splice variants of Plp1 in human and of Cnp in mouse are curated in NCBI RefSeq database, but not for rat. Lack of annotation of splice variants can pose significant challenge for the reliable quantification of gene expression levels in toxicological studies. Therefore, we applied a "comparative sequence analysis" approach, relying on annotated splice variants in human/mouse and on evolutionary conservation of intron-exon structures, to identify additional splice variants of Plp1 and Cnp in rat. Then, we confirmed their identity by nucleotide sequencing and characterized their temporal expression patterns during brain development by RT-PCR. The measurement of total transcripts and individual splice variants of Plp1 and Cnp in the cerebellum of MeHg-exposed rat pups revealed a relatively similar level of reduction in their expression levels. This study further confirms that perinatal exposure to MeHg can impact oligodendrocytes in pups. Based on these observations, we conclude that monitoring the expression of these oligodendrocyte-enriched genes can be useful to identify toxic chemicals affecting myelination. © 2015.
Padhi B.K.,HECSB |
Singh M.,HECSB |
Huang N.,HECSB |
Analytical Biochemistry | Year: 2016
Genomic DNA (gDNA) contamination of RNA samples can lead to inaccurate measurement of gene expression by reverse transcription quantitative real-time PCR (RT-qPCR). We describe an easily adoptable PCR-based method where gDNA contamination in RNA samples is assessed by comparing the amplification of intronic and exonic sequences from a housekeeping gene. Although this alternative assay was developed for rat RNA samples, it could be easily adapted to other species. As a proof of concept, we assessed the effects of detectable gDNA contamination levels on the expression of a few genes that illustrate the importance of RNA quality in acquiring reliable data. © 2015 Published by Elsevier Inc. All rights reserved.