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Pang Z, Lu Y, Zhou G, Hui F, Xu L, Viau C, Spigelman AF, MacDonald PE, Wishart DS, Li S, Xia J. MetaboAnalyst 6.0: towards a unified platform for metabolomics data processing, analysis and interpretation. Nucleic Acids Res 2024:gkae253. [PMID: 38587201 DOI: 10.1093/nar/gkae253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 03/14/2024] [Accepted: 03/26/2024] [Indexed: 04/09/2024] Open
Abstract
We introduce MetaboAnalyst version 6.0 as a unified platform for processing, analyzing, and interpreting data from targeted as well as untargeted metabolomics studies using liquid chromatography - mass spectrometry (LC-MS). The two main objectives in developing version 6.0 are to support tandem MS (MS2) data processing and annotation, as well as to support the analysis of data from exposomics studies and related experiments. Key features of MetaboAnalyst 6.0 include: (i) a significantly enhanced Spectra Processing module with support for MS2 data and the asari algorithm; (ii) a MS2 Peak Annotation module based on comprehensive MS2 reference databases with fragment-level annotation; (iii) a new Statistical Analysis module dedicated for handling complex study design with multiple factors or phenotypic descriptors; (iv) a Causal Analysis module for estimating metabolite - phenotype causal relations based on two-sample Mendelian randomization, and (v) a Dose-Response Analysis module for benchmark dose calculations. In addition, we have also improved MetaboAnalyst's visualization functions, updated its compound database and metabolite sets, and significantly expanded its pathway analysis support to around 130 species. MetaboAnalyst 6.0 is freely available at https://www.metaboanalyst.ca.
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Affiliation(s)
- Zhiqiang Pang
- Institute of Parasitology, McGill University,Sainte-Anne-de-Bellevue, Quebec, Canada
| | - Yao Lu
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada
| | - Guangyan Zhou
- Institute of Parasitology, McGill University,Sainte-Anne-de-Bellevue, Quebec, Canada
| | - Fiona Hui
- Institute of Parasitology, McGill University,Sainte-Anne-de-Bellevue, Quebec, Canada
| | - Lei Xu
- Institute of Parasitology, McGill University,Sainte-Anne-de-Bellevue, Quebec, Canada
| | - Charles Viau
- Institute of Parasitology, McGill University,Sainte-Anne-de-Bellevue, Quebec, Canada
| | - Aliya F Spigelman
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Patrick E MacDonald
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - David S Wishart
- Departments of Biological Sciences and Computing Science, University of Alberta, Edmonton, Alberta, Canada
| | - Shuzhao Li
- The Jackson Laboratory for Genomic Medicine, Farmington, CT, USA
- University of Connecticut School of Medicine, Farmington, CT, USA
| | - Jianguo Xia
- Institute of Parasitology, McGill University,Sainte-Anne-de-Bellevue, Quebec, Canada
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada
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Shiri TJ, Viau C, Gu X, Xu L, Lu Y, Xia J. The Native Microbiome Member Chryseobacterium sp. CHNTR56 MYb120 Induces Trehalose Production via a Shift in Central Carbon Metabolism during Early Life in C. elegans. Metabolites 2023; 13:953. [PMID: 37623896 PMCID: PMC10456584 DOI: 10.3390/metabo13080953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 08/01/2023] [Accepted: 08/11/2023] [Indexed: 08/26/2023] Open
Abstract
Aging is the system-wide loss of homeostasis, eventually leading to death. There is growing evidence that the microbiome not only evolves with its aging host, but also directly affects aging via the modulation of metabolites involved in important cellular functions. The widely used model organism C. elegans exhibits high selectivity towards its native microbiome members which confer a range of differential phenotypes and possess varying functional capacities. The ability of one such native microbiome species, Chryseobacterium sp. CHNTR56 MYb120, to improve the lifespan of C. elegans and to promote the production of Vitamin B6 in the co-colonizing member Comamonas sp. 12022 MYb131 are some of its beneficial effects on the worm host. We hypothesize that studying its metabolic influence on the different life stages of the worm could provide further insights into mutualistic interactions. The present work applied LC-MS untargeted metabolomics and isotope labeling to study the impact of the native microbiome member Chryseobacterium sp. CHNTR56 MYb120 on the metabolism of C. elegans. In addition to the upregulation of biosynthesis and detoxification pathway intermediates, we found that Chryseobacterium sp. CHNTR56 MYb120 upregulates the glyoxylate shunt in mid-adult worms which is linked to the upregulation of trehalose, an important metabolite for desiccation tolerance in older worms.
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Affiliation(s)
- Tanisha Jean Shiri
- Institute of Parasitology, McGill University, Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada; (T.J.S.); (C.V.); (X.G.); (L.X.)
| | - Charles Viau
- Institute of Parasitology, McGill University, Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada; (T.J.S.); (C.V.); (X.G.); (L.X.)
| | - Xue Gu
- Institute of Parasitology, McGill University, Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada; (T.J.S.); (C.V.); (X.G.); (L.X.)
| | - Lei Xu
- Institute of Parasitology, McGill University, Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada; (T.J.S.); (C.V.); (X.G.); (L.X.)
| | - Yao Lu
- Department of Microbiology and Immunology, McGill University, Montreal, QC H3A 2B4, Canada;
| | - Jianguo Xia
- Institute of Parasitology, McGill University, Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada; (T.J.S.); (C.V.); (X.G.); (L.X.)
- Department of Microbiology and Immunology, McGill University, Montreal, QC H3A 2B4, Canada;
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Majumder S, Sackey T, Viau C, Park S, Xia J, Ronholm J, George S. Genomic and phenotypic profiling of Staphylococcus aureus isolates from bovine mastitis for antibiotic resistance and intestinal infectivity. BMC Microbiol 2023; 23:43. [PMID: 36803552 PMCID: PMC9940407 DOI: 10.1186/s12866-023-02785-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 01/30/2023] [Indexed: 02/22/2023] Open
Abstract
BACKGROUND Staphylococcus aureus is one of the prevalent etiological agents of contagious bovine mastitis, causing a significant economic burden on the global dairy industry. Given the emergence of antibiotic resistance (ABR) and possible zoonotic spillovers, S aureus from mastitic cattle pose threat to both veterinary and public health. Therefore, assessment of their ABR status and pathogenic translation in human infection models is crucial. RESULTS In this study, 43 S. aureus isolates associated with bovine mastitis obtained from four different Canadian provinces (Alberta, Ontario, Quebec, and Atlantic provinces) were tested for ABR and virulence through phenotypic and genotypic profiling. All 43 isolates exhibited crucial virulence characteristics such as hemolysis, and biofilm formation, and six isolates from ST151, ST352, and ST8 categories showed ABR. Genes associated with ABR (tetK, tetM, aac6', norA, norB, lmrS, blaR, blaZ, etc.), toxin production (hla, hlab, lukD, etc.), adherence (fmbA, fnbB, clfA, clfB, icaABCD, etc.), and host immune invasion (spa, sbi, cap, adsA, etc.) were identified by analyzing whole-genome sequences. Although none of the isolates possessed human adaptation genes, both groups of ABR and antibiotic-susceptible isolates demonstrated intracellular invasion, colonization, infection, and death of human intestinal epithelial cells (Caco-2), and Caenorhabditis elegans. Notably, the susceptibilities of S. aureus towards antibiotics such as streptomycin, kanamycin, and ampicillin were altered when the bacteria were internalized in Caco-2 cells and C. elegans. Meanwhile, tetracycline, chloramphenicol, and ceftiofur were comparatively more effective with ≤ 2.5 log10 reductions of intracellular S. aureus. CONCLUSIONS This study demonstrated the potential of S. aureus isolated from mastitis cows to possess virulence characteristics enabling invasion of intestinal cells thus calling for developing therapeutics capable of targeting drug-resistant intracellular pathogens for effective disease management.
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Affiliation(s)
- Satwik Majumder
- grid.14709.3b0000 0004 1936 8649Department of Food Science and Agricultural Chemistry, Macdonald Campus, McGill University, Macdonald-Stewart Building, Room-1039, 21, 111 Lakeshore Ste Anne de Bellevue, Quebec, H9X 3V9 Canada
| | - Trisha Sackey
- grid.14709.3b0000 0004 1936 8649Department of Food Science and Agricultural Chemistry, Macdonald Campus, McGill University, Macdonald-Stewart Building, Room-1039, 21, 111 Lakeshore Ste Anne de Bellevue, Quebec, H9X 3V9 Canada
| | - Charles Viau
- grid.14709.3b0000 0004 1936 8649Institute of Parasitology, Macdonald Campus, McGill University, 21, 111 Lakeshore Ste Anne de Bellevue, Quebec, H9X 3V9 Canada
| | - Soyoun Park
- grid.14709.3b0000 0004 1936 8649Department of Food Science and Agricultural Chemistry, Macdonald Campus, McGill University, Macdonald-Stewart Building, Room-1039, 21, 111 Lakeshore Ste Anne de Bellevue, Quebec, H9X 3V9 Canada
| | - Jianguo Xia
- grid.14709.3b0000 0004 1936 8649Institute of Parasitology, Macdonald Campus, McGill University, 21, 111 Lakeshore Ste Anne de Bellevue, Quebec, H9X 3V9 Canada ,grid.14709.3b0000 0004 1936 8649Department of Animal Science, Macdonald Campus, McGill University, 21, 111 Lakeshore Ste Anne de Bellevue, Quebec, H9X 3V9 Canada
| | - Jennifer Ronholm
- grid.14709.3b0000 0004 1936 8649Department of Food Science and Agricultural Chemistry, Macdonald Campus, McGill University, Macdonald-Stewart Building, Room-1039, 21, 111 Lakeshore Ste Anne de Bellevue, Quebec, H9X 3V9 Canada ,grid.14709.3b0000 0004 1936 8649Department of Animal Science, Macdonald Campus, McGill University, 21, 111 Lakeshore Ste Anne de Bellevue, Quebec, H9X 3V9 Canada
| | - Saji George
- Department of Food Science and Agricultural Chemistry, Macdonald Campus, McGill University, Macdonald-Stewart Building, Room-1039, 21, 111 Lakeshore Ste Anne de Bellevue, Quebec, H9X 3V9, Canada.
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Haçariz O, Viau C, Gu X, Xia J. Native Microbiome Members of C. elegans Act Synergistically in Biosynthesis of Pyridoxal 5′-Phosphate. Metabolites 2022; 12:metabo12020172. [PMID: 35208245 PMCID: PMC8879373 DOI: 10.3390/metabo12020172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 02/06/2022] [Accepted: 02/10/2022] [Indexed: 02/04/2023] Open
Abstract
The roles of the healthy microbiome on the host and the relationships between members of the microbiome remain to be fully characterized. Due to the complexity of the interactions between the mammalian microbiome and its host, the use of model organisms such as the nematode worm Caenorhabditis elegans is a promising strategy to study host-microbiome interactions in vivo, as well as bacterial crosstalk within the host. Previously it was found that native bacterial isolates of the worm, Chryseobacterium sp. CHNTR56 MYb120 and Comamonas sp. 12022 MYb131, possess genomic diversity in the biosynthesis of the active form of vitamin B6, pyridoxal 5′-phosphate (PLP), and contribute to host fitness and lifespan extension. However, the relative contribution of PLP from each isolate, as well as the existence of interbacterial relationships within the worm gut remain to be characterized. In the present work, we investigated the presence and measured the abundance of PLP in the isolates and in the worms grown with the isolates using ultraperformance liquid chromatography tandem-mass spectrometry (UPLC-MS/MS). Our analyses confirmed the presence of PLP in vitro and in vivo. The elevated abundance of PLP in the isolates (which reached statistically significant levels when the two isolates were combined), and within worms grown with the combination of bacterial isolates, compared to control, indicated synergism between the isolates in the production of PLP. Isotope labeling revealed that Comamonas sp. 12022 MYb131 was the main provider of PLP in worms grown with the combination of bacterial isolates. The dominance of this isolate inside the worm was further confirmed by a colonization assay. An untargeted metabolomics analysis of the bacteria showed that the pathways related to cell growth, protein synthesis and lipid synthesis/energy production were regulated in the combination group in comparison with Comamonas sp. 12022 MYb131 alone. Furthermore, glutamine, involved in the de novo synthesis of purine and pyrimidines, was specifically abundant in this group, indicating the potential role of this metabolite in initiating and sustaining bacterial growth. This bacterial crosstalk is suggested to promote the growth of Comamonas sp. 12022 MYb131 in vivo, and synthesis of bacterial metabolites such as PLP in the worm gut.
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Affiliation(s)
- Orçun Haçariz
- Institute of Parasitology, McGill University, Montreal, QC H9X 3V9, Canada; (O.H.); (C.V.); (X.G.)
| | - Charles Viau
- Institute of Parasitology, McGill University, Montreal, QC H9X 3V9, Canada; (O.H.); (C.V.); (X.G.)
| | - Xue Gu
- Institute of Parasitology, McGill University, Montreal, QC H9X 3V9, Canada; (O.H.); (C.V.); (X.G.)
| | - Jianguo Xia
- Institute of Parasitology, McGill University, Montreal, QC H9X 3V9, Canada; (O.H.); (C.V.); (X.G.)
- Department of Animal Science, McGill University, Montreal, QC H9X 3V9, Canada
- Correspondence:
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Atkinson LE, Liu Y, McKay F, Vandewyer E, Viau C, Irvine A, Rosa BA, Li Z, Liang Q, Marks NJ, Maule AG, Mitreva M, Beets I, Li L, Mousley A. Ascaris suum Informs Extrasynaptic Volume Transmission in Nematodes. ACS Chem Neurosci 2021; 12:3176-3188. [PMID: 34347433 DOI: 10.1021/acschemneuro.1c00281] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Neural circuit synaptic connectivities (the connectome) provide the anatomical foundation for our understanding of nematode nervous system function. However, other nonsynaptic routes of communication are known in invertebrates including extrasynaptic volume transmission (EVT), which enables short- and/or long-range communication in the absence of synaptic connections. Although EVT has been highlighted as a facet of Caenorhabditis elegans neurosignaling, no experimental evidence identifies body cavity fluid (pseudocoelomic fluid; PCF) as a vehicle for either neuropeptide or biogenic amine transmission. In the parasitic nematode Ascaris suum, FMRFamide-like peptides encoded on flp-18 potently stimulate female reproductive organs but are expressed in cells that are anatomically distant from the reproductive organ, with no known synaptic connections to this tissue. Here we investigate nonsynaptic neuropeptide signaling in nematodes mediated by the body cavity fluid. Our data show that (i) A. suum PCF (As-PCF) contains a catalog of neuropeptides including FMRFamide-like peptides and neuropeptide-like proteins, (ii) the A. suum FMRFamide-like peptide As-FLP-18A dominates the As-PCF peptidome, (iii) As-PCF potently modulates nematode reproductive muscle function ex vivo, mirroring the effects of synthetic FLP-18 peptides, (iv) As-PCF activates the C. elegans FLP-18 receptors NPR-4 and -5, (v) As-PCF alters C. elegans behavior, and (vi) FLP-18 and FLP-18 receptors display pan-phylum distribution in nematodes. This study provides the first direct experimental evidence to support an extrasynaptic volume route for neuropeptide transmission in nematodes. These data indicate nonsynaptic signaling within the nematode functional connectome and are particularly pertinent to receptor deorphanization approaches underpinning drug discovery programs for nematode pathogens.
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Affiliation(s)
- Louise E Atkinson
- Microbes and Pathogen Biology, The Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Belfast BT9 5DL, U.K
| | - Yang Liu
- School of Pharmacy and Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States
| | - Fiona McKay
- Microbes and Pathogen Biology, The Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Belfast BT9 5DL, U.K
| | - Elke Vandewyer
- Department of Biology, KU Leuven, Naamsestraat 59, 3000 Leuven, Belgium
| | - Charles Viau
- Microbes and Pathogen Biology, The Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Belfast BT9 5DL, U.K
| | - Allister Irvine
- Microbes and Pathogen Biology, The Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Belfast BT9 5DL, U.K
| | - Bruce A Rosa
- McDonnell Genome Institute, and Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63108, United States
| | - Zihui Li
- School of Pharmacy and Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States
| | - Qingxiao Liang
- Microbes and Pathogen Biology, The Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Belfast BT9 5DL, U.K
| | - Nikki J Marks
- Microbes and Pathogen Biology, The Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Belfast BT9 5DL, U.K
| | - Aaron G Maule
- Microbes and Pathogen Biology, The Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Belfast BT9 5DL, U.K
| | - Makedonka Mitreva
- McDonnell Genome Institute, and Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63108, United States
| | - Isabel Beets
- Department of Biology, KU Leuven, Naamsestraat 59, 3000 Leuven, Belgium
| | - Lingjun Li
- School of Pharmacy and Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States
| | - Angela Mousley
- Microbes and Pathogen Biology, The Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Belfast BT9 5DL, U.K
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Haçariz O, Viau C, Karimian F, Xia J. The symbiotic relationship between Caenorhabditis elegans and members of its microbiome contributes to worm fitness and lifespan extension. BMC Genomics 2021; 22:364. [PMID: 34011272 PMCID: PMC8136213 DOI: 10.1186/s12864-021-07695-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 05/10/2021] [Indexed: 12/15/2022] Open
Abstract
Background A healthy microbiome influences host physiology through a mutualistic relationship, which can be important for the host to cope with cellular stress by promoting fitness and survival. The mammalian microbiome is highly complex and attributing host phenotypes to a specific member of the microbiome can be difficult. The model organism Caenorhabditis elegans and its native microbiome, discovered recently, can serve as a more tractable, experimental model system to study host-microbiome interactions. In this study, we investigated whether certain members of C. elegans native microbiome would offer a benefit to their host and putative molecular mechanisms using a combination of phenotype screening, omics profiling and functional validation. Results A total of 16 members of C. elegans microbiome were screened under chemically-induced toxicity. Worms grown with Chryseobacterium sp. CHNTR56 MYb120 or Comamonas sp. 12022 MYb131, were most resistant to oxidative chemical stress (SiO2 nanoparticles and juglone), as measured by progeny output. Further investigation showed that Chryseobacterium sp. CHNTR56 positively influenced the worm’s lifespan, whereas the combination of both isolates had a synergistic effect. RNAseq analysis of young adult worms, grown with either isolate, revealed the enrichment of cellular detoxification mechanisms (glutathione metabolism, drug metabolism and metabolism of xenobiotics) and signaling pathways (TGF-beta and Wnt signaling pathways). Upregulation of cysteine synthases (cysl genes) in the worms, associated with glutathione metabolism, was also observed. Nanopore sequencing uncovered that the genomes of the two isolates have evolved to favor the specific route of the de novo synthesis pathway of vitamin B6 (cofactor of cysl enzymes) through serC or pdxA2 homologs. Finally, co-culture with vitamin B6 extended worm lifespan. Conclusions In summary, our study indicates that certain colonizing members of C. elegans have genomic diversity in vitamin B6 synthesis and promote host fitness and lifespan extension. The regulation of host cellular detoxification genes (i.e. gst) along with cysl genes at the transcriptome level and the bacterium-specific vitamin B6 synthesis mechanism at the genome level are in an agreement with enhanced host glutathione-based cellular detoxification due to this interspecies relationship. C. elegans is therefore a promising alternative model to study host-microbiome interactions in host fitness and lifespan. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-021-07695-y.
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Affiliation(s)
- Orçun Haçariz
- Institute of Parasitology, McGill University, Montreal, Quebec, Canada
| | - Charles Viau
- Institute of Parasitology, McGill University, Montreal, Quebec, Canada
| | - Farial Karimian
- Institute of Parasitology, McGill University, Montreal, Quebec, Canada
| | - Jianguo Xia
- Institute of Parasitology, McGill University, Montreal, Quebec, Canada. .,Department of Animal Science, McGill University, Montreal, Quebec, Canada.
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Viau C, Haçariz O, Karimian F, Xia J. Comprehensive phenotyping and transcriptome profiling to study nanotoxicity in C. elegans. PeerJ 2020; 8:e8684. [PMID: 32149031 PMCID: PMC7049462 DOI: 10.7717/peerj.8684] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 02/04/2020] [Indexed: 12/11/2022] Open
Abstract
Engineered nanoparticles are used at an increasing rate in both industry and medicine without fully understanding their impact on health and environment. The nematode Caenorhabditis elegans is a suitable model to study the toxic effects of nanoparticles as it is amenable to comprehensive phenotyping, such as locomotion, growth, neurotoxicity and reproduction. In this study, we systematically evaluated the effects of silver (Ag) and five metal oxide nanoparticles: SiO2, CeO2, CuO, Al2O3 and TiO2. The results showed that Ag and SiO2 exposures had the most toxic effects on locomotion velocity, growth and reproduction, whereas CeO2, Al2O3 and CuO exposures were mostly neurotoxic. We further performed RNAseq to compare the gene expression profiles underlying Ag and SiO2toxicities. Gene set enrichment analyses revealed that exposures to Ag and SiO2consistently downregulated several biological processes (regulations in locomotion, reproductive process and cell growth) and pathways (neuroactive ligand-receptor interaction, wnt and MAPK signaling, etc.), with opposite effects on genes involved in innate immunity. Our results contribute to mechanistic insights into toxicity of Ag and SiO2 nanoparticles and demonstrated that C. elegans as a valuable model for nanotoxicity assessment.
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Affiliation(s)
- Charles Viau
- Institute of Parasitology, McGill University, Montreal, Canada
| | - Orçun Haçariz
- Institute of Parasitology, McGill University, Montreal, Canada
| | - Farial Karimian
- Institute of Parasitology, McGill University, Montreal, Canada
| | - Jianguo Xia
- Institute of Parasitology, McGill University, Montreal, Canada.,Department of Animal Science, McGill University, Montreal, Quebec, Canada
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Soufan O, Ewald J, Viau C, Crump D, Hecker M, Basu N, Xia J. T1000: a reduced gene set prioritized for toxicogenomic studies. PeerJ 2019; 7:e7975. [PMID: 31681519 PMCID: PMC6824333 DOI: 10.7717/peerj.7975] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 10/02/2019] [Indexed: 12/12/2022] Open
Abstract
There is growing interest within regulatory agencies and toxicological research communities to develop, test, and apply new approaches, such as toxicogenomics, to more efficiently evaluate chemical hazards. Given the complexity of analyzing thousands of genes simultaneously, there is a need to identify reduced gene sets. Though several gene sets have been defined for toxicological applications, few of these were purposefully derived using toxicogenomics data. Here, we developed and applied a systematic approach to identify 1,000 genes (called Toxicogenomics-1000 or T1000) highly responsive to chemical exposures. First, a co-expression network of 11,210 genes was built by leveraging microarray data from the Open TG-GATEs program. This network was then re-weighted based on prior knowledge of their biological (KEGG, MSigDB) and toxicological (CTD) relevance. Finally, weighted correlation network analysis was applied to identify 258 gene clusters. T1000 was defined by selecting genes from each cluster that were most associated with outcome measures. For model evaluation, we compared the performance of T1000 to that of other gene sets (L1000, S1500, Genes selected by Limma, and random set) using two external datasets based on the rat model. Additionally, a smaller (T384) and a larger version (T1500) of T1000 were used for dose-response modeling to test the effect of gene set size. Our findings demonstrated that the T1000 gene set is predictive of apical outcomes across a range of conditions (e.g., in vitro and in vivo, dose-response, multiple species, tissues, and chemicals), and generally performs as well, or better than other gene sets available.
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Affiliation(s)
- Othman Soufan
- Institute of Parasitology, McGill University, Montreal, Canada
| | - Jessica Ewald
- Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, Canada
| | - Charles Viau
- Institute of Parasitology, McGill University, Montreal, Canada
| | - Doug Crump
- Ecotoxicology and Wildlife Health Division, Environment and Climate Change Canada, National Wildlife Research Centre, Carleton University, Ottawa, Canada
| | - Markus Hecker
- School of the Environment & Sustainability and Toxicology Centre, University of Saskatchewan, Saskatoon, Canada
| | - Niladri Basu
- Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, Canada
| | - Jianguo Xia
- Institute of Parasitology, McGill University, Montreal, Canada.,Department of Animal Science, McGill University, Montreal, Canada
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Viau C, Wouters JR, Chouinard S. Inhibition of the renal tubular reabsorption of rat beta-2-microglobulin by lysozyme in perfused rat. Contrib Nephrol 2015; 83:88-92. [PMID: 2100725 DOI: 10.1159/000418780] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- C Viau
- Département de Médecine, Université de Montréal, Canada
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Vyskocil A, Truchon G, Leroux T, Lemay F, Gendron M, Gagnon F, Majidi NE, Boudjerida A, Lim S, Emond C, Viau C. A weight of evidence approach for the assessment of the ototoxic potential of industrial chemicals. Toxicol Ind Health 2011; 28:796-819. [PMID: 22064681 DOI: 10.1177/0748233711425067] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
There is accumulating epidemiological evidence that exposure to some solvents, metals, asphyxiants and other substances in humans is associated with an increased risk of acquiring hearing loss. Furthermore, simultaneous and successive exposure to certain chemicals along with noise can increase the susceptibility to noise-induced hearing loss. There are no regulations that require hearing monitoring of workers who are employed at locations in which occupational exposure to potentially ototoxic chemicals occurs in the absence of noise exposure. This project was undertaken to develop a toxicological database allowing the identification of possible ototoxic substances present in the work environment alone or in combination with noise exposure. Critical toxicological data were compiled for chemical substances included in the Quebec occupational health regulation. The data were evaluated only for noise exposure levels that can be encountered in the workplace and for realistic exposure concentrations up to the short-term exposure limit or ceiling value (CV) or 5 times the 8-h time-weighted average occupational exposure limit (TWA OEL) for human data and up to 100 times the 8-h TWA OEL or CV for animal studies. In total, 224 studies (in 150 articles of which 44 evaluated the combined exposure to noise and a chemical) covering 29 substances were evaluated using a weight of evidence approach. For the majority of cases where potential ototoxicity was previously proposed, there is a paucity of toxicological data in the primary literature. Human and animal studies indicate that lead, styrene, toluene and trichloroethylene are ototoxic and ethyl benzene, n-hexane and p-xylene are possibly ototoxic at concentrations that are relevant to the occupational setting. Carbon monoxide appears to exacerbate noise-induced hearing dysfunction. Toluene interacts with noise to induce more severe hearing losses than the noise alone.
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Affiliation(s)
- A Vyskocil
- Institut de recherche en santé publique de l'Université de Montréal, Département de santé environnementale et santé au travail, Université de Montréal, Canada.
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Bouchard M, Viau C, Marie C, Maître A. Apport de la toxicocinétique dans le suivi biologique des expositions aux hydrocarbures aromatiques polycycliques. ARCH MAL PROF ENVIRO 2010. [DOI: 10.1016/j.admp.2010.03.026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Le Sage V, Zhu L, Lepage C, Portt A, Viau C, Daigle F, Gruenheid S, Le Moual H. An outer membrane protease of the omptin family prevents activation of the Citrobacter rodentium PhoPQ two-component system by antimicrobial peptides. Mol Microbiol 2009; 74:98-111. [PMID: 19708916 DOI: 10.1111/j.1365-2958.2009.06854.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The PhoPQ two-component system of the intracellular pathogen Salmonella enterica senses and controls resistance to alpha-helical antimicrobial peptides (AMPs) by regulating covalent modifications of lipid A. A homologue of the phoPQ operon was found in the genome of the murine enteric extracellular pathogen, Citrobacter rodentium. Here we report that C. rodentium PhoPQ was apparently unable to mediate activation of target genes in the presence of alpha-helical AMPs. However, these AMPs activated C. rodentium PhoPQ expressed in a S. entericaDeltaphoPQ mutant. Analysis of the outer membrane (OM) fractions of the C. rodentium wild-type and DeltaphoPQ strains led to the identification of an omptin family protease (CroP) that was absent in DeltaphoPQ. Deletion of croP in C. rodentium resulted in higher susceptibility to alpha-helical AMPs, indicating a direct role of CroP in AMP resistance. CroP greatly contributed to the protection of the OM from AMP damage by actively degrading alpha-helical AMPs before they reach the periplasmic space. Accordingly, transcriptional activation of PhoP-regulated genes by alpha-helical AMPs was restored in the DeltacroP mutant. This study shows that resistance to alpha-helical AMPs by the extracellular pathogen C. rodentium relies primarily on the CroP OM protease.
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Affiliation(s)
- Valerie Le Sage
- Department of Microbiology and Immunology andFaculty of Dentistry, McGill University, Montreal, QC, H3A 2B4, Canada.Department of Microbiology and Immunology, University of Montreal, Montreal, QC, H3C 3J7, Canada
| | - Lei Zhu
- Department of Microbiology and Immunology andFaculty of Dentistry, McGill University, Montreal, QC, H3A 2B4, Canada.Department of Microbiology and Immunology, University of Montreal, Montreal, QC, H3C 3J7, Canada
| | - Christine Lepage
- Department of Microbiology and Immunology andFaculty of Dentistry, McGill University, Montreal, QC, H3A 2B4, Canada.Department of Microbiology and Immunology, University of Montreal, Montreal, QC, H3C 3J7, Canada
| | - Andrea Portt
- Department of Microbiology and Immunology andFaculty of Dentistry, McGill University, Montreal, QC, H3A 2B4, Canada.Department of Microbiology and Immunology, University of Montreal, Montreal, QC, H3C 3J7, Canada
| | - Charles Viau
- Department of Microbiology and Immunology andFaculty of Dentistry, McGill University, Montreal, QC, H3A 2B4, Canada.Department of Microbiology and Immunology, University of Montreal, Montreal, QC, H3C 3J7, Canada
| | - France Daigle
- Department of Microbiology and Immunology andFaculty of Dentistry, McGill University, Montreal, QC, H3A 2B4, Canada.Department of Microbiology and Immunology, University of Montreal, Montreal, QC, H3C 3J7, Canada
| | - Samantha Gruenheid
- Department of Microbiology and Immunology andFaculty of Dentistry, McGill University, Montreal, QC, H3A 2B4, Canada.Department of Microbiology and Immunology, University of Montreal, Montreal, QC, H3C 3J7, Canada
| | - Hervé Le Moual
- Department of Microbiology and Immunology andFaculty of Dentistry, McGill University, Montreal, QC, H3A 2B4, Canada.Department of Microbiology and Immunology, University of Montreal, Montreal, QC, H3C 3J7, Canada
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Vyskocil A, Leroux T, Truchon G, Lemay F, Gendron M, Gagnon F, El Majidi N, Viau C. Ethyl benzene should be considered ototoxic at occupationally relevant exposure concentrations. Toxicol Ind Health 2009; 24:241-6. [PMID: 19022877 DOI: 10.1177/0748233708094097] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Organic solvents can produce ototoxic effects in both man and experimental animals. The objective of this study was to review the literature on the effects of low-level exposure to ethyl benzene on the auditory system and consider its relevance for the occupational settings. Both human and animal investigations were evaluated only for realistic exposure concentrations based on the permissible exposure limits. In Quebec, the Time-Weighed Average Exposure Value for 8A h (TWAEV) is 100A ppm (434A mg/m(3)) and the Short-Term Exposure Value for 15A min (STEV) is 125A ppm (543A mg/m(3)). In humans, the upper limit for considering ototoxicity data relevant to the occupational exposure situation was set at STEV. Animal data were evaluated only for exposure concentrations up to 100 times the TWAEV. In workers, there is no evidence of either ethyl benzene-induced hearing losses or ototoxic interaction after combined exposure to ethyl benzene and noise. In rats, ethyl benzene affects the auditory function mainly in the cochlear mid-frequency range and ototoxic interaction was observed after combined exposure to noise and ethyl benzene. Further studies with sufficient data on the ethyl benzene exposure of workers are necessary to make a definitive conclusion. Given the current evidence from animal studies, we recommend considering ethyl benzene as an ototoxic agent.
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Affiliation(s)
- A Vyskocil
- Département de santé environnementale et santé au travail, Université de Montréal, Montréal, Québec, Canada.
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Vyskocil A, Leroux T, Truchon G, Lemay F, Gagnon F, Gendron M, Viau C. Ototoxicity of trichloroethylene in concentrations relevant for the working environment. Hum Exp Toxicol 2009; 27:195-200. [PMID: 18650250 DOI: 10.1177/0960327108090267] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Organic solvents can cause hearing loss themselves or promote noise-induced hearing loss. The objective of this study was to review the literature on the effects of low-level exposure to trichloroethylene on the auditory system and consider its relevance for the occupational settings. Both human and animal investigations were evaluated only for realistic exposure concentrations based on the Quebec permissible exposure limits: 50 ppm 8-h time-weighed average exposure value (TWAEV) and 200 ppm short-term exposure value (STEV). In humans, the upper limit for considering ototoxicity data relevant to the occupational exposure situation was set at the STEV. Animal data were evaluated only for exposure concentrations up to 100 times the TWAEV. There is no convincing evidence of trichloroethylene-induced hearing losses in workers. In rats, trichloroethylene affects the auditory function mainly in the cochlear mid- to high-frequency range with a lowest observed adverse effect level (LOAEL) of 2000 ppm. No studies on ototoxic interaction after combined exposure to noise and trichloroethylene were identified in humans. In rats, supra-additive interaction was reported. Further studies with sufficient data on the trichloroethylene exposure of workers are necessary to make a definitive conclusion. In the interim, we recommend considering trichloroethylene as an ototoxic agent.
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Affiliation(s)
- A Vyskocil
- Département de santé environnementale et santé au travail, Université de Montréal, Montreal, Quebec, Canada.
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Abstract
The ability of chemicals to produce hearing loss themselves or to promote noise-induced hearing loss has been reported for some organic solvents. The objective of this study was to review the literature on the effects of low-level exposure to n-hexane on the auditory system and consider its relevance for occupational settings. Both human and animal investigations were evaluated only for realistic exposure concentrations based on the permissible inhalation exposure limits. In Quebec, the time-weighted average exposure value (TWAEV) for 8 h is 50 ppm. In humans, the upper limit for considering ototoxicity data relevant to the occupational exposure situation was set at five times the TWAEV. Animal data were evaluated only for exposure concentrations up to 100 times the TWAEV. There is no convincing evidence of n-hexane-induced hearing loss in workers. In rats, n-hexane seems to affect auditory function; however, the site of these alterations cannot be determined from the present data. Further studies with sufficient data on the exposure of workers to n-hexane are necessary to make a definitive conclusion. In the interim, we recommend considering n-hexane as a possibly ototoxic agent.
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Affiliation(s)
- A Vyskocil
- Groupe de recherche interdisciplinaire en santé and Département de santé environnementale et santé au travail, Université de Montréal, Montréal, Québec, Canada.
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Ruzgyte A, Bouchard M, Viau C. Comparison of the urinary excretion time courses of pyrene-1,6-dione, pyrene-1,8-dione and 1-hydroxypyrene in rats intravenously exposed to pyrene. Biomarkers 2008; 11:417-27. [PMID: 16966159 DOI: 10.1080/13547500600733622] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The urinary excretion time courses of pyrene-1,6-dione (P16D), pyrene-1,8-dione (P18D) and 1-hydroxypyrene (1-OHP) were compared in Sprague-Dawley and Wistar rats. Groups of five male rats, of about 200 g of body weight, were injected intravenously with 0.05, 0.5, 5 and 50 micromol pyrene kg-1 of body weight. Urine was collected at 2, 4, 6, 8, 10, 12, 18, 24, 30, 42 and 48 h post-dosing. Pyrene metabolites were measured by high-performance liquid chromatography (HPLC)/fluorescence after enzymatic hydrolysis of the glucurono- and sulfo-conjugates, extraction on Sep-Pak C18 cartridges and, for the analysis of dione metabolites, derivatization to stable diacetoxypyrene molecules. Over the 48-h sampling period, on average 17.4-25.6% of the injected pyrene was excreted overall as P16D, 6.4-8.8% as P18D and 0.6-0.8% as 1-OHP in the urine of Sprague-Dawley rats. By comparison, on average 10.3-14.7% of the intravenous pyrene dose was recovered as P16D, 4.8-6.4% as P18D and 0.3-0.4% as 1-OHP in the urine of Wistar rats. In both strains of rats there was no clear effect of the dose on the 0-48-h cumulative urinary excretion of P18D and 1-OHP over the entire dose range, while the percentage of dose recovered overall as P16D in urine at the highest dose (50 micromol kg-1) was statistically lower than at the other doses. The 0-48-h cumulative percentage of pyrene dose excreted as metabolites in the urine of Sprague-Dawley rats was also significantly higher than in Wistar rats (p<0.01) exposed under identical conditions. As for the urinary excretion-time courses of the different metabolites, for a given dose and strain of rats, excretion curves of P16D, P18D and 1-OHP generally evolved in parallel. There was also no clear effect of the dose on the excretion rate, thus half-life, of pyrene metabolites, except for P16D in Sprague-Dawley rats at the highest dose where elimination tended to be slower compared with the other doses (p<0.01). The average first-order elimination half-life of P16D, P18D and 1-OHP was 4.0, 5.7 and 4.1 h, respectively, in Sprague-Dawley rats, and 5.1, 6.1 and 5.1 h, respectively, in Wistar rats (all doses combined but excluding the highest dose for P16D). This study showed the relative importance of metabolic pathways leading to diones compared with 1-OHP. These dioxygenated metabolites appear to be interesting biomarkers of pyrene exposure at environmentally and occupationally relevant doses. Their adequacy as biomarkers of human exposure has yet to be confirmed.
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Affiliation(s)
- A Ruzgyte
- Département de santé environnementale et santé au travail, Faculté de Médecine, Université de Montréal, Montreal, Quebec, Canada
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Viau C. Interprétation des résultats de surveillance biologique. ARCH MAL PROF ENVIRO 2008. [DOI: 10.1016/j.admp.2008.03.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Faucher SP, Viau C, Gros PP, Daigle F, Le Moual H. The prpZ gene cluster encoding eukaryotic-type Ser/Thr protein kinases and phosphatases is repressed by oxidative stress and involved in Salmonella enterica serovar Typhi survival in human macrophages. FEMS Microbiol Lett 2008; 281:160-6. [PMID: 18312574 DOI: 10.1111/j.1574-6968.2008.01094.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
The prpZ gene cluster consists of three ORFs coding for proteins with homology to eukaryotic-type Ser/Thr protein phosphatases 2C (prpZ) and Ser/Thr protein kinases (prkY and prkX). This cluster is present in the sequenced genomes of Salmonella enterica serovar Typhi (S. Typhi) strains Ty2 and CT18. This study investigated the genetic organization of this gene cluster, its regulation and its putative involvement in virulence. The three genes are transcribed as a polycistronic mRNA as demonstrated by reverse transcriptase (RT)-PCR. Analysis of a prpZ::lacZ transcriptional fusion showed that the prpZ locus is expressed throughout the growth phase. LacZ activity and real-time RT-PCR showed that transcription of the mRNA is negatively regulated upon exposure of cells to HOCl and, to a lesser extent, hydrogen peroxide. A deletion mutant of the prpZ gene cluster showed a significantly lower level of survival than the parental strain Ty2 in human macrophages at 48 h postinfection. Together these data suggest that prpZ, prkY and prkX are virulence genes that may be part of a signaling pathway controlling long-term survival of S. Typhi in host cells.
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Affiliation(s)
- Sébastien P Faucher
- Department of Microbiology and Immunology, University of Montreal, Montreal, Quebec, Canada
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Viau C, Pungartnik C, Schmitt MC, Basso TS, Henriques JAP, Brendel M. Sensitivity to Sn2+ of the yeast Saccharomyces cerevisiae depends on general energy metabolism, metal transport, anti-oxidative defences, and DNA repair. Biometals 2006; 19:705-14. [PMID: 16691319 DOI: 10.1007/s10534-006-9007-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2005] [Accepted: 03/18/2006] [Indexed: 10/24/2022]
Abstract
Resistance to stannous chloride (SnCl(2)) of the yeast Saccharomyces cerevisiae is a product of several metabolic pathways of this unicellular eukaryote. Sensitivity testing of different null mutants of yeast to SnCl(2) revealed that DNA repair contributes to resistance, mainly via recombinational (Rad52p) and error-prone (Rev3p) steps. Independently, the membrane transporter Atr1p/Snq1p (facilitated transport) contributed significantly to Sn(2+)-resistance whereas absence of ABC export permease Snq2p did not enhance sensitivity. Sensitivity of the superoxide dismutase mutants sod1 and sod2 revealed the importance of these anti-oxidative defence enzymes against Sn(2+)-imposed DNA damage while a catalase-deficient mutant (ctt1) showed wild type (WT) resistance. Lack of transcription factor Yap1, responsible for the oxidative stress response in yeast, led to 3-fold increase in Sn(2+)-sensitivity. While loss of mitochondrial DNA did not change the Sn(2+)-resistance phenotype in any yeast strain, cells with defect cytochrome c oxidase (CcO mutants) showed gradually enhanced sensitivities to Sn(2+) and different spontaneous mutation rates. Highest sensitivity to Sn(2+) was observed when yeast was in exponential growth phase under glucose repression. During diauxic shift (release from glucose repression) Sn(2+)-resistance increased several hundred-fold and fully respiring and resting cells were sensitive only at more than 1000-fold exposure dose, i.e. they survived better at 25 mM than exponentially growing cells at 25 microM Sn(2+). This phenomenon was observed not only in WT but also in already Sn(2+)-sensitive rad52 as well as in sod1, sod2 and CcO mutant strains. The impact of metabolic steps in contribution to Sn(2+)-resistance had the following ranking: Resting WT cells > membrane transporter Snq1p > superoxide dismutases > transcription factor Yap1p >or= DNA repair >> exponentially growing WT cells.
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Affiliation(s)
- C Viau
- Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, UFRGS, Porto Alegre, RS, Brasil
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Pungartnik C, Viau C, Picada J, Caldeira-de-Araújo A, Henriques JAP, Brendel M. Genotoxicity of stannous chloride in yeast and bacteria. Mutat Res 2005; 583:146-57. [PMID: 15927871 DOI: 10.1016/j.mrgentox.2005.03.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2005] [Revised: 03/07/2005] [Accepted: 03/17/2005] [Indexed: 10/25/2022]
Abstract
Stannous chloride was found genotoxic in microbial test systems of the yeast Saccharomyces cerevisiae, in one strain of Salmonella typhimurium and in the Mutoxitest of Escherichia coli. Five isogenic haploid yeast strains differing only in a particular repair-deficiency had the following ranking in Sn2+ -sensitivity: rad52delta>rad6delta>rad2delta>rad4delta>RAD, indicating a higher relevance of recombinogenic repair mechanisms than nucleotide excision in repair of Sn2+ -induced DNA damage. Sn2+ -treated cells formed aggregates that lead to gross overestimation of toxicity when not undone before diluting and plating. Reliable inactivation assays at exposure doses of 25-75 mM SnCl2 were achieved by de-clumping with either EDTA- or phosphate buffer. Sn2+ -induced reversion of the yeast his1-798, his1-208 and lys1-1 mutant alleles, in diploid and haploid cells, respectively, and putative frameshift mutagenesis (reversion of the hom3-10 allele) was observed. In diploid yeast, SnCl2 induced intra-genic mitotic recombination while inter-genic (reciprocal) recombination was very weak and not significant. Yeast cells of exponentially growing cultures were killed to about the same extend at 0.1% of SnCl2 than respective cells in stationary phase, suggesting a major involvement of physiological parameters of post-diauxic shift oxidative stress resistance in enhanced Sn2+ -tolerance. Superoxide dismutases, but not catalase, protected against SnCl2-induced reactive oxygen species as sod1delta had a three-fold higher sensitivity than the WT while the sod2delta mutant was only slightly more sensitive but conferred significant sensitivity increase in a sod1delta sod2delta double mutant. In the Salmonella reversion assay, SnCl2 did not induce mutations in strains TA97, TA98 or TA100, while a positive response was seen in strain TA102. SnCl2 induced a two-fold increase in mutation in the Mutoxitest strain IC203 (uvrA oxyR), but was less mutagenic in strain IC188 (uvrA). We propose that the mutagenicity of SnCl2 in yeast and bacteria occurs via error-prone repair of DNA damage that is produced by reactive oxygen species.
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Affiliation(s)
- C Pungartnik
- Dept. de Biofísica, Centro de Biotecnologia, UFRGS, Av. Bento Gonçalves 9500, 91507-970 Porto Alegre, RS, Brazil
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Drolet D, Vyskocil A, Viau C, Lemay F, Brodeur J, Tardif R, Gérin M, Lapointe G, Truchon G, Baril M. Les mélanges de substances en milieu de travail : un utilitaire pour l’évaluation du risque toxicologique. ARCH MAL PROF ENVIRO 2004. [DOI: 10.1016/s1775-8785(04)93044-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Viau C, Lafontaine M, Payan JP. Creatinine normalization in biological monitoring revisited: the case of 1-hydroxypyrene. Int Arch Occup Environ Health 2004; 77:177-85. [PMID: 14760537 DOI: 10.1007/s00420-003-0495-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2003] [Accepted: 11/14/2003] [Indexed: 11/30/2022]
Abstract
OBJECTIVES To compare the apparent urinary excretion rates of both creatinine and 1-hydroxypyrene (1-OHP) and to assess the value of creatinine normalization for both toxicokinetic analysis and the routine examination of workers. METHODS All urine samples were collected from individuals who had been exposed to polycyclic aromatic hydrocarbons (PAHs), occupationally and non-occupationally, for at least 24 consecutive hours. Urinary creatinine and 1-OHP were determined. 1-OHP excretion rates were expressed either as a function of creatinine excretion rate or as unadjusted values. Theoretical relationships between creatinine-normalized excretion of metabolites and body weight-adjusted inhaled dose were drawn for men with a constant body mass index. RESULTS Creatinine excretion rate paralleled 1-OHP excretion rate. The plot of creatinine excretion rate-adjusted excretion rate of 1-OHP vs time led to smooth curves for determination of toxicokinetic parameters. Creatinine normalization was adequate, even for samples with a urinary creatinine concentration below 0.5 g/l or above 3 g/l. A theoretical analysis revealed that men weighing between 50 kg and 100 kg, exposed to a constant dose of a pollutant producing a urinary metabolite excreted by the same mechanism as creatinine, would exhibit a body weight-adjusted dose span of 2 with an accompanying creatinine-normalized metabolite excretion span of 2.23-fold. CONCLUSION The kinetics of creatinine excretion parallels that of 1-OHP, and a creatinine excretion rate-normalized excretion rate of 1-OHP appears to allow for a better determination of the toxicokinetic parameters of 1-OHP urinary excretion. At least in the case of 1-OHP, creatinine normalization seems valid, even for very dilute or very concentrated urine samples. Finally, because creatinine normalization not only compensates for variable diuresis but also correlates better with the body weight-adjusted dose of the parent compound, it should be used in biological monitoring of exposure to (PAHs) pyrene and to other substances whose urinary biomarker excretion kinetics parallel that of creatinine.
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Affiliation(s)
- C Viau
- Department of Environmental and Occupational Health, University of Montreal, Main Station, P.O. Box 6128, Montreal, Quebec, H3C 3J7, Canada.
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Viau C, Zaoui C, Charbonneau S. Dietary fibers reduce the urinary excretion of 1-hydroxypyrene following intravenous administration of pyrene. Toxicol Sci 2003; 78:15-9. [PMID: 14691205 DOI: 10.1093/toxsci/kfh052] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
During biological monitoring of exposure to a chemical, a possible source of interindividual variability in the measurement of a urinary metabolite that undergoes enterohepatic cycling is the presence of dietary fiber in the gastrointestinal tract. This study examined the effect of diets containing either the insoluble fiber Alphacel (nonnutritive bulk cellulose) or the soluble pectin (from citrus fruit, MW 20,000-40,000). Five groups of male Sprague-Dawley rats received one of the following diets: poor (5% w/w) or rich (15% w/w) in Alphacel, poor (5% w/w) or rich (15% w/w) in pectin, or no fiber (NF). Five micromol/kg of pyrene was administered by iv injection immediately after feeding the animals with their respective diet, and urine and feces collections started for the determination of 1-hydroxypyrene (1-OHP), a metabolite of pyrene. The type of fiber had no influence on the results. The rats receiving diets both poor and rich in fiber excreted less 1-OHP (18 +/- 8 and 15 +/- 7 pmol per g of rat, respectively) in the 24-h urine samples than the NF group (28 +/- 6 pmol/g). There was a nonstatistically significant trend towards increased fecal and total (urinary + fecal) 1-OHP excretion with increasing amount of fiber in the diet. An in vitro experiment showed an inverse correlation (r(2) = 0.98) between the amount of Alphacel in suspension in a 1-OHP aqueous solution and the recovery of 1-OHP from the soluble fraction. The reduction in urinary output of the metabolite due to fiber reaching approximately 40% may contribute to its interindividual variability observed in occupational and environmental studies.
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Affiliation(s)
- C Viau
- Human Toxicology Research Group, Department of Environmental and Occupational Health, University of Montreal, P.O. Box 6128, Main Station, Montreal (QC), Canada H3C 3J7.
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Camus M, Vyskocil A, Viau C. 708 Epidemiological validation of environmental cancer risk assessments: A case study in populations exposed to polycyclic aromatic hydrocarbons. Toxicol Lett 2003. [DOI: 10.1016/s0378-4274(03)90707-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Ska B, Vyskocil A, Tardif R, Carrier G, Thuot R, Muray K, Viau C. Effects of peak concentrations on the neurotoxicity of styrene in volunteers. Hum Exp Toxicol 2003; 22:407-15. [PMID: 12948080 DOI: 10.1191/0960327103ht384oa] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The manufacture of fibreglass reinforced plastic products may give rise to substantial peak exposures to styrene. Such exposure patterns need further consideration in terms of styrene neurotoxicity. The aim of this study was to evaluate the neurotoxic effects of short-term peak exposures in volunteers, at levels respecting the Quebec occupational exposure limits (8 hours time weighed average of 213 mg/m3 and 15 min average of 426 mg/ m3). The volunteers had not been previously exposed to styrene and they had no documented exposure to known neurotoxicants during the study. Twenty-four volunteers were exposed to five exposure scenarios during 6 hours: a, stable exposure to 106 mg/m3; b, variable exposure with a mean concentration of 106 mg/m3 with four 15 min peaks mounting up to 213 mg/m3; c, stable exposure to 213 mg/m3; d, variable exposure with a mean concentration of 213 mg/m3 and four peaks of 426 mg/m3 and e, two stable exposures to 5 mg/m3 (control). Before and after each exposure scenario, volunteers were submitted to a battery of sensory tests (visual and olfactory), neuropsychological tests (reaction time, attention, memory, psychomotor function), and self-evaluation questionnaires (mood and symptoms) in a test-retest design. The results show that the different exposure scenarios involving peak exposures did not influence either the performance to any test or subjective signs and symptoms. However, due caution must be exercised in extrapolation of the current results to occupational exposure since only acute exposures were tested and volunteers were at rest during exposure, which resulted in lower doses than those experienced by physically active workers.
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Affiliation(s)
- B Ska
- Ecole d'orthophonie et d'audiologie, Faculté de médecine, Université de Montréal, Montréal, Québec, Canada
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Fiala Z, Vyskocil A, Krajak V, Viau C, Ettlerova E, Bukac J, Fialova D, Emminger S. Environmental exposure of small children to polycyclic aromatic hydrocarbons. Int Arch Occup Environ Health 2001; 74:411-20. [PMID: 11563604 DOI: 10.1007/s004200100239] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVES The aim of the study was to assess the intake (by various routes of exposure) of polycyclic aromatic hydrocarbons (PAH) by children living in a Czech city, and its effect on excretion of 1-hydroxypyrene (1-OHP) in summer and winter periods. METHODS Four groups of children (3-6 years old) were chosen: (1) two groups from a kindergarten situated in the city center with a higher traffic density ("polluted" area); (2) two groups from a kindergarten situated in a green zone of the same city ("non-polluted" area). Food consumption was recorded in all children and PAH intake from foodstuffs was estimated. Ambient air samples were collected from the playground and inside the kindergartens. Soil samples were collected too. Morning and evening urine samples were collected during sampling days. RESULTS In both seasons, the mean outdoor total PAH concentration (sum of 12 individual PAH) in the -polluted" area was approximately three-times higher than that in the "non-polluted" area. Indoor concentration in the "polluted" area was more than six-times higher than that in the "non-polluted" area in summer, and almost three-times higher in winter. The same trend was observed for pyrene and for the sum of carcinogenic PAH. The contribution to the total pyrene absorbed dose from food consumption was much more important than that from inhalation and from ingestion of soil dust. Significantly higher urinary concentrations of 1-OHP (evening samples) were found in children from the "polluted" kindergarten in both seasons. The number of significant relationships between 1-OHP and pyrene absorbed dose was weak. CONCLUSIONS Food seems to be the main source of total pyrene and total PAH intake in small children, even under relatively higher air PAH exposure in the city. Estimated pyrene ingestion from soil had a negligible contribution to the total pyrene absorbed dose. Urinary 1-OHP seems to be an uncertain (non-sensitive) marker of the environmental inhalation exposure to pyrene (PAH) if the pollution of air by pyrene (PAH) is not excessive and the pyrene (PAH) dose by this route is much less than by ingestion. Usefulness of the urinary 1-OHP as an indicator of overall environmental exposure to PAH needs further investigation.
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Affiliation(s)
- Z Fiala
- Department of Hygiene and Preventive Medicine, Charles University in Prague, Medical Faculty in Hradec Králové, Czech Republic.
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Vyskocil A, Viau C. Proposal for reference concentrations (RfC) for inhalation exposure to methanol. Environ Toxicol Pharmacol 2000; 9:9-18. [PMID: 11137463 DOI: 10.1016/s1382-6689(00)00057-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A tentative reference concentration (RfC) for methanol in ambient air, i.e. an exposure concentration below which adverse effects are not expected to occur, was derived from the analysis of the toxicological data available in the literature. Well-documented studies that correlate environmental levels of methanol with observed toxic effects have not been found in the literature, nor have any long-term epidemiological studies of chronic low-level occupational exposure been found. Assessment of RfC for acute inhalation exposure is based on a human study (n=26 subjects) with a 'tentative' NOAEL of 262 mg/m(3). The calculated RfC for 1 h exposure is 104.8 mg/m(3). The RfC is given a low confidence rating as there was only one methanol concentration used. A well designed study on monkeys served as the basis for the assessment of RfC for chronic inhalation exposure. In this study, 13.1 and 131 mg/m(3) were considered as NOAEL and LOAEL, respectively. The calculated RfC is 0.38 mg/m(3). The overall database is weak, lacking data on reproductive and developmental endpoints in human or non-human primates. Nevertheless, the RfC is given a medium confidence rating because of the strength of the principal study.
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Affiliation(s)
- A Vyskocil
- Département de Santé Environnementale et Santé au Travail, Faculté de Médecine, Université de Montréal, c.p. 6128, succursale Centre-ville, Québec, H3C 3J7, Montréal, Canada
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Viau C, Hakizimana G, Bouchard M. Indoor exposure to polycyclic aromatic hydrocarbons and carbon monoxide in traditional houses in Burundi. Int Arch Occup Environ Health 2000; 73:331-8. [PMID: 10963417 DOI: 10.1007/s004209900112] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Wood combustion is used as a major energy source in African countries and could result in indoor, pollution-related health problems. This exploratory study was undertaken to estimate polycyclic aromatic hydrocarbon (PAH) and carbon monoxide exposure in individuals living in traditional rural houses in Burundi. METHODS Standard methods were used to determine indoor air concentrations of 12 PAHs, and carbon monoxide. The urinary excretion of 1-hydroxypyrene (1-OHP) was measured in occupants of traditional houses, and compared with that of individuals living in the town of Bujumbura, the capital of Burundi. RESULTS Mean airborne concentration of four volatile PAHs, naphthalene, fluorene, phenanthrene and acenaphthene, exceeded 1 microg/m3, and that of benzo(a)pyrene was 0.07 microg/m3. Naphthalene was by far the main PAH contaminant, with a mean concentration (+/- standard deviation) of 28.7+/-23.4 microg/m3, representing on average 60-70% of total PAH concentration. Carbon monoxide mean concentration (+/- standard deviation) was 42+/-31 mg/m3, and correlated with total PAH concentration. Geometric mean urinary 1-OHP excretion (range) in people living in traditional houses was 1.50 (0.26-15.62) micromol/mol creatinine, a value which is on average 30 times higher than that of people living in the capital (0.05 (0.009-0.17) micromol/mol creatinine). CONCLUSIONS It appears that the substantially high concentrations of the studied contaminants constitute a potential health hazard to the rural population of Burundi.
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Affiliation(s)
- C Viau
- Département de médecine du travail et d'hygiène du milieu, Université de Montréal, Québec, Canada.
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Vyskocil A, Fiala Z, Chénier V, Krajak L, Ettlerova E, Bukac J, Viau C, Emminger S. Assessment of multipathway exposure of small children to PAH. Environ Toxicol Pharmacol 2000; 8:111-118. [PMID: 10867370 DOI: 10.1016/s1382-6689(00)00032-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The aim of study was to assess the uptake of polycyclic aromatic hydrocarbons (PAH) by children living in a city and its effect on 1-hydroxypyrene (1-OHP) excretion. Two groups of children (n=11 and 13; 3-6 years old) were chosen: (1) a group from a kindergarten situated near a road with a high traffic density ('polluted' area); (2) a group from a kindergarten situated in a green zone ('non polluted' area). Food consumption was recorded in all children and PAH uptake from foodstuffs was estimated. Ambient air samples were collected on the playground and indoor of kindergartens during 3 days in summer 1997. Soil samples were collected on the playground. Urine samples were collected in the morning and in the evening. Mean outdoor total PAH concentration (sum of 12 individual PAH) in 'polluted' area was 12 times higher than that in 'non polluted' area (22.9 vs. 1.9 ng/m(3)). However, indoor concentrations were similar (3.0 vs. 2.1 ng/m(3)). The same trend was observed for pyrene concentrations. The contribution to the total pyrene absorbed dose from food consumption (estimated daily absorbed dose of 167 and 186 ng, respectively, in 'polluted' and 'non polluted' area) was much more important than that from inhalation (8.4 and 5.4 ng, respectively) in both areas. The estimated daily absorbed doses of pyrene from the soil were 0.061 and 0.104 ng in 'polluted' and 'non polluted' kindergarten, respectively, which correspond to 0.032 and 0.059% of the total absorbed dose. Higher urinary concentrations of 1-OHP were found in children from 'polluted' kindergarten. In conclusion, the food seems to be a main source of the total pyrene and total PAH uptake in small children, even under a relative high PAH air exposure in the city. Pyrene concentration in soil had a negligible contribution to the total pyrene absorbed dose. Usefulness of the urinary 1-OHP as an indicator of the environmental exposure to PAH needs further research.
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Affiliation(s)
- A Vyskocil
- Département de médecine du travail et d'hygiène du milieu, Faculté de médecine, Université de Montréal, c.p. 6128, Succursale Centre-ville, Québec, H3C 3J7, Montréal, Canada
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Haddad S, Tardif R, Viau C, Krishnan K. A modeling approach to account for toxicokinetic interactions in the calculation of biological hazard index for chemical mixtures. Toxicol Lett 1999; 108:303-8. [PMID: 10511275 DOI: 10.1016/s0378-4274(99)00102-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Biological hazard index (BHI) is defined as biological level tolerable for exposure to mixture, and is calculated by an equation similar to the conventional hazard index. The BHI calculation, at the present time, is advocated for use in situations where toxicokinetic interactions do not occur among mixture constituents. The objective of this study was to develop an approach for calculating interactions-based BHI for chemical mixtures. The approach consisted of simulating the concentration of exposure indicator in the biological matrix of choice (e.g. venous blood) for each component of the mixture to which workers are exposed and then comparing these to the established BEI values, for calculating the BHI. The simulation of biomarker concentrations was performed using a physiologically-based toxicokinetic (PBTK) model which accounted for the mechanism of interactions among all mixture components (e.g. competitive inhibition). The usefulness of the present approach is illustrated by calculating BHI for varying ambient concentrations of a mixture of three chemicals (toluene (5-40 ppm), m-xylene (10-50 ppm), and ethylbenzene (10-50 ppm)). The results show that the interactions-based BHI can be greater or smaller than that calculated on the basis of additivity principle, particularly at high exposure concentrations. At lower exposure concentrations (e.g. 20 ppm each of toluene, m-xylene and ethylbenzene), the BHI values obtained using the conventional methodology are similar to the interactions-based methodology, confirming that the consequences of competitive inhibition are negligible at lower concentrations. The advantage of the PBTK model-based methodology developed in this study relates to the fact that, the concentrations of individual chemicals in mixtures that will not result in a significant increase in the BHI (i.e. > 1) can be determined by iterative simulation.
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Affiliation(s)
- S Haddad
- Groupe de Recherche en Toxicologie Humaine (TOXHUM), Université de Montréal, Canada
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Abstract
Five experiments were conducted in male Sprague-Dawley rats regarding the kinetic of urinary excretion of 1-hydroxypyrene (1-OHP) following i.v., oral and dermal exposure to 0.5-50 micromol/kg pyrene either as a single substance or as mixture of various polycyclic aromatic hydrocarbons (PAH). Frequent urine collections over 48 h after exposure and a tissue versus time distribution experiment using [14C]pyrene allowed to define the kinetic profile of both pyrene and 1-OHP. For all exposure routes, there is a linear relationship over two orders of magnitude between the dose of pyrene and the urinary excretion of 1-OHP. Differences in biliary/urinary 1-OHP excretion ratio in canulated rats (3) versus faecal/urinary 1-OHP excretion ratio in non-canulated rats (0.6) indicate major enterohepatic recirculation of the metabolite. Half-lives of both pyrene and 1-OHP in all measured tissues were all comprised between 3.1 and 5.4 h, and 5.2-6.7 h, respectively, so that no long term accumulation would be predicted from these values for any tissue. Binary and ternary mixtures involving naphthalene and benzo(a)pyrene in addition to pyrene has no influence on the urinary excretion profile of 1-OHP. All these observations led to the proposal of a dynamic compartment model of pyrene and metabolite flows indicating that following rapid initial distribution to fatty tissues, pyrene is rapidly biotransformed into various metabolites and undergoes major enterohepatic recycling. Part of the initially formed and part of the recirculated 1-OHP eventually undergoes urinary excretion such that close to 60% of pyrene is eliminated as metabolites in urine by 24 h after injection while 20% is excreted in the faeces over the same period.
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Affiliation(s)
- C Viau
- Equipe de Recherche en Surveillance Biologique, Université de Montréal, Station Centre-Ville, Canada.
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Abstract
In an attempt to define a tolerable daily intake (TDI) for molybdenum based on a toxicological risk analysis approach, a large literature survey was conducted. In man, absorption of molybdenum after oral intake is in the range of 28-77% and urinary excretion is 17-80% of the total dose. A low order of toxicity of molybdenum compounds has been observed in humans. However, with the available data, it is not possible to calculate any dose-response or dose-effect relationships. Because molybdenum toxicity is associated with copper intake or depleted copper stores in the body, humans who have an inadequate intake of dietary copper or some dysfunction in their copper metabolism that makes them copper-deficient could be at greater risk of molybdenum toxicity. In the absence of relevant human studies, animal studies were evaluated for the derivation of the TDI. Effects of Mo on reproduction and foetal development were found to be critical effects observed in rats and mice. A dose-response relationship was observed in a study by Fungwe et al., with a 'no observed adverse effect' level (NOAEL) and a 'lowest observed adverse effect' level (LOAEL) of 0.9 and 1.6 mg Mo kg(-1) day(-1), respectively. Applying uncertainty factors of 10 for intraspecies and 10 for interspecies differences to the NOAEL, a TDI of 0.009 mg Mo kg(-1) day(-1) was calculated. The TDI is given a medium confidence rating. This TDI is more than double the upper limit of adequate intake for adolescents and adults that was derived from the Mo content of the average diet in the USA.
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Affiliation(s)
- A Vyskocil
- Département de médecine du travail et d'hygiène du milieu, Faculté de médecine, Université de Montréal, Québec, Canada.
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Bouchard M, Krishnan K, Viau C. Kinetics of tissue distribution and elimination of pyrene and 1-hydroxypyrene following intravenous administration of [14C]pyrene in rats. Toxicol Sci 1998; 46:11-20. [PMID: 9928664 DOI: 10.1006/toxs.1998.2525] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The tissue distribution and elimination of pyrene and 1-hydroxypyrene (1-OHP) were evaluated in male Sprague-Dawley rats (210-240 g) following an intravenous injection of 50 micromol/kg of [14C]pyrene. Blood and tissues were removed and urine and feces were collected at 1, 2, 4, 8, 16, and 24 h postdosing. [14C]Pyrene equivalents were measured by liquid scintillation counting, and beta-glucuronidase/arylsulfatase-treated blood, tissues, and excreta were analyzed for pyrene and 1-OHP by HPLC/fluorescence. At 1 h, the largest fraction of the dose was found in adipose tissue, essentially as pyrene, and its elimination followed first-order monophasic kinetics with a half-life (t(1/2)) of 4.9 h. In blood, liver, kidney, lung, muscle, and gastrointestinal (GI) tract, kinetics of [14C]pyrene equivalents were biphasic and average t(1/2) values for the terminal elimination phase (8 to 24 h) ranged between 6.2 and 8.7 h. Elimination of pyrene in blood and these tissues except the GI tract followed first-order biphasic kinetics with average t(1/2) values of the terminal phase ranging between 3.6 and 5.4 h. In the GI tract, a monophasic elimination kinetics of pyrene was observed with mean t(1/2) value of 3.1 h. Kinetics of 1-OHP in blood and liver showed a monophasic elimination with mean t(1/2) values of 6.7 and 6.2 h, respectively. Kinetics of 1-OHP in the other tissues were biphasic with average t(1/2) values of the terminal elimination phase ranging between 5.2 and 6.2 h. At 24 h, on average, 81.7% of the dose was recovered in the urine (57.2%), feces (18.3%), and GI tract (6.2%) as [14C]pyrene equivalents with 2.7 and 1.9% of dose excreted as total 1-OHP in urine and feces, respectively. At all time points, 1-OHP in urine represented a constant fraction of total 14C in urine and feces. These results indicate that (i) [14C]pyrene was rapidly distributed, metabolized, and eliminated from the body, and (ii) although 1-OHP represents a small percentage of total pyrene eliminated from the body, it remains a reliable indicator of systemic exposure to, and overall elimination of the 14C associated with, this polycyclic aromatic hydrocarbon.
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Affiliation(s)
- M Bouchard
- Département de médecine du travail et d'hygiène du milieu, Faculté de médecine, Université de Montréal, Québec, Canada
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Bouchard M, Krishnan K, Viau C. Urinary excretion kinetics of 1-hydroxypyrene following intravenous administration of binary and ternary mixtures of polycyclic aromatic hydrocarbons in rat. Arch Toxicol 1998; 72:475-82. [PMID: 9765062 DOI: 10.1007/s002040050531] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The effect of exposure to binary and ternary mixtures of polycyclic aromatic hydrocarbons (PAHs) on the urinary excretion kinetics of 1-hydroxypyrene (1-OHP) has been examined. Male Sprague-Dawley rats were administered intravenously 5 micromol/kg of pyrene alone or in combination with 0.5, 5 and 25 micromol/kg of either naphthalene, benzo(a)pyrene (BaP), or both. Urine samples were collected at frequent intervals over 48 h. The kinetics of 1-OHP in urine was not altered by the presence of either naphthalene or BaP in the mixtures, at least from 4 h post-dosing. Hence, none of the injected mixtures significantly modified the first-order apparent elimination half-life of 1-OHP in urine obtained for the 12 to 42 h period post injection where mean values ranged between 6.2 and 9.6 h. However, while the presence of naphthalene or the low BaP dose of 0.5 micromol/kg in the mixtures did not have a significant effect on the total excretion of 1-OHP, BaP doses of 5 and 25 micromol/kg in the mixtures significantly increased the amount of 1-OHP excreted in urine. Mean percentages of the pyrene dose excreted as 1-OHP after injection of pyrene in combination with 0.5, 5 and 25 micromol/kg BaP were respectively increased 1.3, 2.2 and 2.6 times compared to the value obtained after administration of pyrene alone. The percentages determined after concomitant administration of pyrene and 0.5, 5 and 25 micromol/kg of BaP plus naphthalene were 1.4, 1.8 and 2.4 times, respectively, the value obtained after administration of pyrene singly. The observed effect of BaP (5 or 25 micromol/kg) on 1-OHP total excretion appears to result from BaP induction of pyrene metabolism. Lack of effect of naphthalene appears to be due to its weak P450 1A1 enzyme induction capacity. Absence of significant effect of the low BaP dose in the mixtures (0.5 micromol/kg) suggests that 1-OHP in urine is useful as a bioindicator of occupational and environmental exposures to PAH mixtures.
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Affiliation(s)
- M Bouchard
- Département de médecine du travail et d'hygiéne du milieu, Faculté de médecine, Université de Montréal, Québec, Canada
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Abstract
The subchronic inhalation toxicity of a methanol/gasoline blend (85% methanol, 15% gasoline, v/v) was studied in rats. Sprague Dawley rats (10 animals per group) of both sexes were exposed to vapours of methanol/gasoline at 50/3, 500/30 and 5000/300ppm for 6 hours per day, 5 days per week, for 13 weeks. Control animals inhaled filtered room air only. Control recovery and high dose recovery groups were also included which inhaled room air for an extra 4 weeks following the treatment period. No clinical signs of toxicity were observed in the treatment group and their growth curves were not significantly different from the control. Except for decreased forelimb grip strength in high dose females, no treatment-related neurobehavioural effects (4-6 hours post inhalation) were observed using screening tests which included cage-side observations, righting reflex, open field activities, and forelimb and hindlimb grip strength. At necropsy, the organ to body weight ratios for the liver, spleen, testes, thymus and lungs were not significantly different from the control group. There were no treatment-related effects in the hematological endpoints and no elevation in serum formate levels. Minimal serum biochemical changes were observed with the only treatment-related change being the decreased creatinine in the females. A dose-related increase in urinary ascorbic acid was detected in males after 2, 4 and 8 weeks of exposure, but not after the 12th week, and in females only at week-2. Increased urinary albumin was observed in treated males starting at the lowest dose and at all exposure periods, but not in females. A treatment-related increase in urinary beta 2-microglobulin was detected in males at week-2 only. Except for mild to moderate mucous cell metaplasia in nasal septum B, which occurred more often and with a slightly higher degree of severity in the low dose groups of both sexes, and presence of a minimal degree of interstitial lymphocyte infiltration in the prostate glands in the high dose males. No other significant microscopic changes were observed in the tissues of treated animals. Based on the marked increase in urinary ascorbic acid and albumin in the high dose males and the decreased forelimb grip strength in the high dose females, we concluded that the no-observed adverse effect level (NOAEL) of methanol/gasoline vapour is 500/30 ppm.
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Affiliation(s)
- R Poon
- Environmental Health Directorate, Health Protection Branch, Ottawa, Canada.
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Abstract
The urinary and biliary excretion kinetics of 1-hydroxypyrene (1-OHP) were compared in male Sprague-Dawley rats exposed intravenously and orally to 1.5, 5, 15, 50 and 100 micromol/kg pyrene. Urine and bile samples were collected at 6-h intervals for up to 24 h. Results showed that the kinetics of 1-OHP were similar for both biliary and urinary excretion whatever the administered dose or exposure route. Furthermore, the time course of 1-OHP excretion in either bile or urine following intravenous dosing resembled that observed after oral administration. In addition, the exposure route and dose had no significant effect on the fraction of dose recovered in urine and bile as 1-OHP after 6, 12, 18 and 24 h post-dosing. Following intravenous injection of 1.5, 5, 15, 50 and 100 micromol/kg pyrene, the mean cumulative percent of dose excreted as 1-OHP in urine over 24 h ranged from 1.7 to 3.2%, while biliary values ranged from 6.5 to 9.5%. Correspondingly, after oral administration, on average, 2.6-3.3% of dose was excreted as 1-OHP in urine and 7.9-10.9% was recovered in bile. Overall, the linear dose-excretion relationship following either exposure routes supports the usefulness of 1-OHP in urine as a bioindicator of polycyclic aromatic hydrocarbon (PAH) exposure. Results further suggest that tissue uptake and distribution of intravenously and orally administered pyrene proceeds similarly. By comparing these data with predicted values from a previously published physiologically based pharmacokinetic model for pyrene in the rat, it also appears that a small fraction of pyrene dose (12%) remains in the body after 24 h and that metabolites other than 1-OHP as measured in the current study are present in significant proportions in urine and feces.
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Affiliation(s)
- M Bouchard
- Département de médecine du travail et d'hygiène du milieu, Faculté de médecine, Université de Montréal, Québec, Canada
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Abstract
PAN is one of a class of common air pollutants formed by the action of sunlight on volatile organic compounds and nitrogen oxides. No toxicokinetic studies have been found in the available literature. The acute toxicity of PAN is less than that of ozone, similar to NO2 and higher than SO2. The LC30, in mice and rats were 718-743 mg/m3 (for 2 h) and 470 mg/m3 (for 4 h), respectively. Following acute exposure, severe lung lesions and, at the higher levels, damage to the epithelium of upper parts of the respiratory tract were found in animals. It seems that concentrations of 1.19-1.49 mg/m3 lie not far from the threshold required for pulmonary function effects in sensitive individuals. However, these PAN concentrations are well above the maximum ambient concentrations usually experienced within the USA and Canada (0.003-0.078 mg/m3). It appears unlikely that present ambient PAN concentrations would affect pulmonary functions responses to ambient ozone. In human, the lowest level causing eye irritations was 0.64 mg/m3 for 2 h. Concentrations of 0.99 and 4.95 mg/m3 were identified as no-observed-effect level (NOEL) and no-observed-adverse-effect level (NOAEL) for pathological and histological changes in the respiratory system (nasal passages) of rats during subchronic exposures to PAN, but were not considered to be relevant to derivation of a RfC for chronic inhalation exposure. PAN is a weak point mutagen or clastogen. The data are not sufficient to evaluate its carcinogenicity. No study was found which could be used for the derivation of a RfC for acute or chronic inhalation exposure to PAN.
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Affiliation(s)
- A Vyskocil
- Département de médecine du travail et d'hygiène du milieu, Faculté de médecine, Université de Montréal, Ottawa, Canada
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Abstract
1 Objectives of this study were (1) to compare concentrations of individual polycyclic aromatic hydrocarbons (PAH) in air of polluted and nonpolluted area of Czech Republic during winter and summer periods and (2) to verify if urinary 1-hydroxypyrene (1-OHP), as supposed practical biological marker, permits the assessment of spacial and temporal variations in environmental PAH exposure. 2 The study population consisted of three groups: (1) a group of 22 physical exercise students who regularly train outside, from the university situated in a polluted town, spending 14 days in winter and 14 days in summer in 'non-polluted' mountains; (2) a control group of 22 residents from the town and (3) a control group of 18 residents from the mountains. 3 The total PAH concentrations (sum of 13 individual PAH) were 19.3 and 104.6 ng/m3 in town and in mountains, respectively, during summer and 86.6 and 261 ng/m3 during winter. 4 Median 1-OHP levels ranged between 0.03 and 0.13 mumol/mol creatinine for controls and between 0.04 and 0.12 mumol/mol creatinine for students. No relationship was found between pyrene levels in air and group means of urinary 1-OHP. Our results show that other factors (probably PAH in food) contribute in masking air pollution influence on urinary 1-OHP levels in subjects non-occupationally exposed to PAH.
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Affiliation(s)
- A Vyskocil
- Departement de médecine du travail et d'hygiène du milieu, Faculté de médecine, Université de Montréal, Canada
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Abstract
OBJECTIVES To assess environmental exposure to polycyclic aromatic hydrocarbons (PAHs) in the vicinity of a Söderberg aluminium reduction plant in Shawinigan, Canada with urinary 1-hydroxypyrene (1-OHP) as a biomarker. METHODS Urine samples were collected from 20 non-occupationally exposed subjects living less than 500 m from the plant and from 20 controls living in Trois-Rivières, another industrial town 40 km from Shawinigan. Concentrations of 1-OHP were measured by high performance liquid chromatography (HPLC). RESULTS Among controls, geometric mean (range) 1-OHP concentrations were 0.046 (0.012-0.116) mumol/mol creatinine in non-smokers and 0.125 (0.051-0.282) mumol/mol creatinine in smokers. Among exposed subjects, values were 0.103 (0.056-0.196) mumol/mol creatinine in non-smokers and 0.250 (0.112-0.448) mumol/mol creatinine in smokers. Excretion of 1-OHP was significantly higher in exposed subjects than in controls among non-smokers and smokers (P < 0.05). CONCLUSION Based on urinary 1-OHP as a biomarker, it seems that living near an industrial point source of PAHs is associated with higher exposure. The health significance of this finding will require further investigation.
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Affiliation(s)
- N L Gilbert
- Département de médecine du travail et d'hygiène du milieu, Université de Montréal, Québec, Canada
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41
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Bouchard M, Viau C. Urinary excretion of benzo[a]pyrene metabolites following intravenous, oral, and cutaneous benzo[a]pyrene administration. Can J Physiol Pharmacol 1997. [DOI: 10.1139/y97-017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Bouchard M, Viau C. Urinary excretion of benzo[a]pyrene metabolites following intravenous, oral, and cutaneous benzo[a]pyrene administration. Can J Physiol Pharmacol 1997; 75:185-92. [PMID: 9164700 DOI: 10.1139/cjpp-75-3-185] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The effect of the administration route, dose, and sampling time on the total urinary excretion of four major benzo[a]pyrene (BaP) metabolites, 3-hydroxyBaP (3-OHBaP), 9-hydroxyBaP 9-hydroxyBaP (9-OHBaP), trans-4,5-dihydrodiolBaP (4,5-diolBaP), and trans-9,10-dihydrodiolBaP (9,10-diolBaP), was studied in male Sprague-Dawley rats exposed to a single intravenous, oral, and cutaneous dose of 2, 6, 20, and 60 mumol BaP/kg. Urine samples were collected at 24-h intervals following treatment. Over the 0-72 h period and for a given dose, amounts of BaP metabolites were 3-OHBaP > 4,5-diolBaP > > 9-OHBaP following intravenous and oral dosing, and 3-OHBaP > > 9-OHBaP > or = 4,5-diolBaP after cutaneous treatment. 9,10-diolBaP was barely detected. On the other hand, amounts of 3-OHBaP and 4,5-diolBaP excreted in urine over the 0-72 h period and for a given dose appeared in the following order: intravenous approximately oral > or = cutaneous. Amounts of 9-OHBaP excreted varied as follows: oral > or = cutaneous > intravenous. For all routes of administration, excretion of 4,5-diolBaP was almost complete over the 0-24 h period in contrast with 3-OHBaP and 9-OHBaP. Peak excretion of 3-OHBaP and 9-OHBaP was reached in the 0-24 h period following intravenous and oral treatment and in the 24-48 h period following cutaneous application. Overall, for a given administration route and dose, there were variations in the time profiles between metabolites. In general, there was nonetheless a good correlation between the BaP dose and urinary excretion of 3-OHBaP, 9-OHBaP, and 4,5-diolBaP. Furthermore, total urinary excretion of a specific metabolite, its time profile, and the relative proportion of the metabolites studied depended on the administration route. Data also suggest that a measure of the concentration ratio of the different metabolites could reflect the time and main route of exposure.
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Affiliation(s)
- M Bouchard
- Départment de médecine du travail et d'hygiène du milieu, Université de Montréal, QC, Canada
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43
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Gérin M, Patrice S, Bégin D, Goldberg MS, Vyskocil A, Adib G, Drolet D, Viau C. A study of ethylene glycol exposure and kidney function of aircraft de-icing workers. Int Arch Occup Environ Health 1997; 69:255-65. [PMID: 9138000 DOI: 10.1007/s004200050145] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Ethylene glycol levels were measured in 154 breathing zone air samples and in 117 urine samples of 33 aviation workers exposed to de-icing fluid (basket operators, de-icing truck drivers, leads and coordinators) studied during 42 worker-days over a winter period of 2 months at a Montreal airport. Ethylene glycol as vapour did not exceed 22 mg/m3 (mean duration of samples 50 min). Mist was quantified at higher levels in 3 samples concerning 1 coordinator and 2 basket operators (76-190 mg/m3, 45-118 min). In 16 cases workers' post-shift or next-morning urine contained quantities of ethylene glycol exceeding 5 mmol/mol creatinine (up to 129 mmol/mol creatinine), with most of these instances occurring in basket operators and coordinators, some of whom did not wear paper masks and/or were accidentally sprayed with de-icing fluid. Diethylene glycol was also found in a few air and urinary samples at levels around one tenth those of ethylene glycol. Urinary concentrations of albumin, beta-N-acetyl-glucosaminidase, beta-2-microglobulin and retinol-binding protein were measured and compared over various periods, according to subgroups based on exposure level and according to the frequency of extreme values. These analyses did not demonstrate acute or chronic kidney damage that could be attributed to working in the presence of ethylene glycol. In conclusion, this study does not suggest important health effects of exposure to de-icing fluid in this group of workers. Potential for overexposure exists, however, in certain work situations, and recommendations on preventive measures are given. In addition, these results suggest that other routes of absorption than inhalation, such as the percutaneous route, may be important and that urinary ethylene glycol may be a useful indicator of exposure to ethylene glycol.
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Affiliation(s)
- M Gérin
- Département de médecine du travail et d'hygiène du milieu, Université de Montréal, Québec, Canada.
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Bouchard M, Viau C. Urinary excretion kinetics of pyrene and benzo(a)pyrene metabolites following intravenous administration of the parent compounds or the metabolites. Toxicol Appl Pharmacol 1996; 139:301-9. [PMID: 8806846 DOI: 10.1006/taap.1996.0169] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The detailed urinary excretion profiles of 1-hydroxypyrene (1-OHP) and benzo(a)pyrene (BaP) metabolites were studied following acute intravenous administration of pyrene and BaP, respectively, or after injection of the metabolites themselves. Male Sprague-Dawley rats were exposed to 4 mumol 1-OHP/kg or 15 mumol pyrene/kg. Other rats were exposed to 2 mumol/kg of a mixture of four BaP metabolites (3-hydroxyBaP (3-OHBaP), 9-hydroxyBaP (9-OHBaP), trans-4,5-dihydrodiolBaP (4,5-diolBaP), and trans-9,10-dihydrodiol (9,10-diolBaP)) or 40 mumol BaP/kg. Urine samples were collected at frequent intervals over 48 or 96 hr. Injection of both pyrene and 1-OHP produced similar biphasic excretion profiles. An apparent first order half life of 6.9 and 6.6 hr, respectively, could be calculated for the second phase of elimination. Comparable 3-OHBaP excretion profiles were obtained after injection of BaP or a mixture of BaP metabolites. Elimination kinetics showed at least two steps, the second step having a first order apparent half life of 8.1 and 7.6 hr following BaP and BaP metabolites injection, respectively. Time profiles of 4,5-diolBaP excretion following administration of BaP or a mixture of BaP metabolites were almost identical. Elimination was linear and a first order apparent half life of 3.1 and 3.6 hr could be calculated. Elimination of 4,5-diolBaP was much more rapid than that of 3-OHBaP and complete within 24 hr postdosing. Therefore, results suggest that (1) phase I biotransformation is not the rate-limiting step in the excretion of 1-OHP, and 3-OHBaP and 4,5-diolBaP following injection of pyrene and BaP, respectively and (2) similarities in the first order apparent half life of 3-OHBaP and 1-OHP for the late phase of excretion suggest that 1-OHP could be a good surrogate for 3-OHBaP.
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Affiliation(s)
- M Bouchard
- Départment de médecine du travail et d'hygiène du milieu, Université de Montréal, Canada
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45
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Abstract
Groups of ten male and female weanling Sprague-Dawley rats were fed diet containing 0, 5, 50, 500 or 5000 ppm of a medium-chain chlorinated paraffin (C14-17, 52% chlorination) for a period of 13 weeks. Increased relative liver weight was observed at 500 and 5000 ppm in females and at 5000 ppm in males. Relative kidney weight was increased at 5000 ppm in both sexes. Serum cholesterol was increased in the females in a dose-related manner starting at 50 ppm. At 5000 ppm, animals of both sexes had elevated hepatic UDP-glucuronosyltransferase activity while only females showed increased aminopyrine N-demethylase activity. Increased urinary N-acetylglucosaminidase activity occurred at 5000 ppm in females. Increased urinary ascorbic acid excretion monitored at week 12 and a decreased hepatic vitamin A level were detected in females receiving the 500 ppm diet and male and female rats at 5000 ppm. Mild, adaptive histopathological changes were detected in the liver of rats of both sexes at 500 and 5000 ppm, and in the thyroid of males and females starting at 500 and 50 ppm respectively. Minimal changes were observed in the kidney proximal tubules of male rats fed the 5000 ppm diet and in the inner medulla tubules of female rats fed the 500 and 5000 ppm diets. These data indicate that the medium-chain chlorinated paraffin produces biochemical and histological changes at dietary levels of greater than or = 50 ppm in females and greater than or = 500 ppm in males.
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Affiliation(s)
- R Poon
- Environmental and Occupational Toxicology Division, Health Canada, Ottawa
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46
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Vyskocil A, Viau C, Brodeur J. The maximal urinary mercury concentration in pregnant women. Toxicol Lett 1995. [DOI: 10.1016/0378-4274(95)94983-n] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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47
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Bouchard M, Viau C. Benzo(a)pyrenediolepoxide-hemoglobin adducts and 3-hydroxy-benzo(a)pyrene urinary excretion profiles in rats subchronically exposed to benzo(a)pyrene. Arch Toxicol 1995; 69:540-6. [PMID: 8534197 DOI: 10.1007/s002040050209] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The time profiles of benzo(a)pyrenediolepoxide (BaPDE)-hemoglobin (Hb) adduct formation and 3-hydroxybenzo(a)pyrene (3-OHBaP) urinary excretion were studied in male Sprague-Dawley rats exposed to daily benzo(a)pyrene (BaP) intraperitoneal doses of 1.25, 6.25, and 31.25 mumol/kg administered Tuesday to Friday for 4 consecutive weeks. Blood was withdrawn weekly, on Tuesdays, prior to dosing. Twenty-four-hour urine samples were collected on Mondays (following 72 h without treatment) and Thursdays. Analytes were quantified by high performance liquid chromatography (HPLC)/fluorescence. Exposure to BaP resulted in the accumulation of BaPDE-Hb adducts, reaching an average of 1.2 +/- 0.3, 8.3 +/- 1.9, and 38.2 +/- 6.1 pmol/g Hb for the 1.25, 6.25, and 31.25 mumol/kg per day doses after 4 weeks of treatment. The expected saw tooth excretion profile of 3-OHBaP was observed, with peaks on Thursdays and troughs on Mondays, and showed a progressive rise on both Mondays and Thursdays. Increase in Monday values with time suggested a possible increase in BaP body burden during exposure. To verify this aspect further, the urinary excretion kinetic of 3-OHBaP following acute intraperitoneal dosing (31.25 mumol/kg) was determined. Urine samples were collected at frequent timed intervals for up to 164 h post-dosing. Two-step elimination was observed, the second step having a half-life of 25 h, presumably linked to the slow release of BaP accumulated in fatty tissues upon repeated treatment.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- M Bouchard
- Département de médecine du travail et d'hygiène du milieu, Université de Montréal, Québec, Canada
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48
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Abstract
Female Wistar rats were given 1% or 0.1% lead acetate in drinking water for 2 or 4 months, respectively. Urinary beta 2-microglobulin, N-acetyl-beta-D-glucosaminidase, lactate dehydrogenase and lysozyme were used as markers of tubular dysfunction. Excretion of albumin and glomerular filtration rate were used as indicators of glomerular impairment. Kidney and body weights and morphological changes in the kidney were also studied. Exposure to 1% lead acetate induced a mean blood lead level of 1730 micrograms l-1 and caused only an increase of beta 2-microglobulin excretion and relative kidney weight. Light microscopy of kidney revealed morphological changes mainly in the epithelial cells of the proximal tubules. The role of acetate or reduced water intake on kidney function was excluded because 1% sodium acetate or the restriction of water intake to the volume consumed by the rats of the lead-exposed group was ineffective. Exposure to 0.1% lead acetate induced a blood lead level of 376 micrograms l-1, corresponding to the current level in industry workers, without any sign of nephrotoxicity. Comparison of this study with the results of a previous study on male rats indicates no sex difference in the nephrotoxicity of lead.
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Affiliation(s)
- A Vyskocil
- Département de médecine du travail et hygiène du milieu, Université de Montréal, Québec, Canada
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49
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Abstract
Velnacrine maleate (Mentane) is an aminoacridine drug developed for the treatment of Alzheimer's disease. Although velnacrine maleate has not been observed to cause prominent cytotoxicity in in vitro hepatocyte cultures, this drug was associated with elevated serum levels of hepatic enzymes in clinical trials. The purpose of the present study was to manipulate cultures of rat hepatocytes in an attempt to elicit a cytotoxic response from this drug and to better understand the in vitro mechanisms of action. Cytotoxicity was evaluated by measuring lactate dehydrogenase (LDH) leakage, neutral red (NR) uptake, and 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyl tetrazolium bromide (MTT) reduction. Preliminary studies with fluorescent probes did not indicate a role for calcium influx or the formation of reactive oxygen species in the cytotoxicity of velnacrine maleate. However, depletion of cellular glutathione (GSH) by diamide (DA) pretreatment resulted in a cytotoxic response at concentrations of velnacrine maleate (1 and 10 micrograms/ml) which were approximately 25-fold lower than those in the absence of DA. Similarly, pretreatment with velnacrine maleate enhanced the cytotoxicity of DA. Pre-exposure of cells to a mixture of DA and t-butyl hydroperoxide (t-BHP) at non-toxic concentrations resulted in significant cytotoxicity of the hepatocyte cultures by velnacrine maleate. Results from these studies indicate that oxidative stress and GSH depletion may enhance Alzheimer patients' susceptibility to the hepatotoxic potential of aminoacridine drugs.
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Affiliation(s)
- S al Casey
- University of Texas, College of Pharmacy, Division of Pharmacology and Toxicology, Austin, USA
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50
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Viau C, Carrier G, Vyskocil A, Dodd C. Urinary excretion kinetics of 1-hydroxypyrene in volunteers exposed to pyrene by the oral and dermal route. Sci Total Environ 1995; 163:179-186. [PMID: 7716496 DOI: 10.1016/0048-9697(95)04494-l] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Two well-informed human volunteers were exposed to 500 micrograms pyrene by ingestion and by dermal application, in two separate experiments. Urinary measurements of 1-hydroxypyrene (1-OHP) were performed on all micturitions taken at intervals of 0.5-4 h for a total period of 48 h after dosing. Following the absorption phase, 1-OHP is excreted with a first order apparent half-life of approximately 12 h for both volunteers and both exposure routes. These results compare well with other previously published studies. A more refined analysis of the data was performed using a two-compartment toxicokinetic model for 'pyrene' (its fraction eventually excreted as 1-OHP). As it was found that a classical first-order system did not adequately fit the data, a non-linear term was introduced in the model for the elimination of urinary 1-OHP. Computer iteration performed on the oral absorption data allowed an estimation of various toxicokinetic parameter values. The mean intercompartmental exchange (k12 and k21) and elimination coefficients were 0.010, 0.006 and 0.012 min-1, respectively. The first two values compare well with those previously published for the rat, whereas the latter is smaller in humans. These values were used to satisfactorily simulate the experimental data for both routes of exposure, adjusting only for kabs which was estimated at 0.014 and 0.0029 min-1 for the oral and dermal exposure, respectively. The proposed model generates new hypotheses on the metabolism of pyrene. The information collected will contribute to the validation of the utilisation of 1-OHP as a biological indicator of exposure to pyrene.
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Affiliation(s)
- C Viau
- Département de Médecine du Travail et Hygiène du Milieu, Université de Montréal, Station Centre-ville, Quebec, Canada
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