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Analytical Method Development for 19 Alkyl Halides as Potential Genotoxic Impurities by Analytical Quality by Design. Molecules 2022; 27:molecules27144437. [PMID: 35889310 PMCID: PMC9320377 DOI: 10.3390/molecules27144437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 07/05/2022] [Accepted: 07/07/2022] [Indexed: 12/10/2022] Open
Abstract
Major issues in the pharmaceutical industry involve efficient risk management and control strategies of potential genotoxic impurities (PGIs). As a result, the development of an appropriate method to control these impurities is required. An optimally sensitive and simultaneous analytical method using gas chromatography with a mass spectrometry detector (GC–MS) was developed for 19 alkyl halides determined to be PGIs. These 19 alkyl halides were selected from 144 alkyl halides through an in silico study utilizing quantitative structure–activity relationship (Q-SAR) approaches via expert knowledge rule-based software and statistical-based software. The analytical quality by design (QbD) approach was adopted for the development of a sensitive and robust analytical method for PGIs. A limited number of literature studies have reviewed the analytical QbD approach in the PGI method development using GC–MS as the analytical instrument. A GC equipped with a single quadrupole mass spectrometry detector (MSD) and VF-624 ms capillary column was used. The developed method was validated in terms of specificity, the limit of detection, quantitation, linearity, accuracy, and precision, according to the ICH Q2 guideline.
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Issitt T, Sweeney ST, Brackenbury WJ, Redeker KR. Sampling and Analysis of Low-Molecular-Weight Volatile Metabolites in Cellular Headspace and Mouse Breath. Metabolites 2022; 12:599. [PMID: 35888722 PMCID: PMC9315489 DOI: 10.3390/metabo12070599] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 06/08/2022] [Accepted: 06/15/2022] [Indexed: 02/04/2023] Open
Abstract
Volatile compounds, abundant in breath, can be used to accurately diagnose and monitor a range of medical conditions. This offers a noninvasive, low-cost approach with screening applications; however, the uptake of this diagnostic approach has been limited by conflicting published outcomes. Most published reports rely on large scale screening of the public, at single time points and without reference to ambient air. Here, we present a novel approach to volatile sampling from cellular headspace and mouse breath that incorporates multi-time-point analysis and ambient air subtraction revealing compound flux as an effective proxy of active metabolism. This approach to investigating breath volatiles offers a new avenue for disease biomarker discovery and diagnosis. Using gas chromatography mass spectrometry (GC/MS), we focus on low molecular weight, metabolic substrate/by-product compounds and demonstrate that this noninvasive technique is sensitive (reproducible at ~1 µg cellular protein, or ~500,000 cells) and capable of precisely determining cell type, status and treatment. Isolated cellular models represent components of larger mammalian systems, and we show that stress- and pathology-indicative compounds are detectable in mice, supporting further investigation using this methodology as a tool to identify volatile targets in human patients.
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Affiliation(s)
- Theo Issitt
- Department of Biology, University of York, York YO10 5DD, UK; (T.I.); (S.T.S.); (W.J.B.)
- York Biomedical Research Institute, University of York, York YO10 5DD, UK
| | - Sean T. Sweeney
- Department of Biology, University of York, York YO10 5DD, UK; (T.I.); (S.T.S.); (W.J.B.)
- York Biomedical Research Institute, University of York, York YO10 5DD, UK
| | - William J. Brackenbury
- Department of Biology, University of York, York YO10 5DD, UK; (T.I.); (S.T.S.); (W.J.B.)
- York Biomedical Research Institute, University of York, York YO10 5DD, UK
| | - Kelly R. Redeker
- Department of Biology, University of York, York YO10 5DD, UK; (T.I.); (S.T.S.); (W.J.B.)
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Afifah NN, Diantini A, Intania R, Abdulah R, Barliana MI. Genetic Polymorphisms and the Efficacy of Platinum-Based Chemotherapy: Review. Pharmgenomics Pers Med 2020; 13:427-444. [PMID: 33116759 PMCID: PMC7549502 DOI: 10.2147/pgpm.s267625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Accepted: 09/07/2020] [Indexed: 11/23/2022] Open
Abstract
Previous studies have indicated that genetic variations in individuals may result in changes in gene expression and amino acids. The effect of these changes may lead to different responses to platinum-based chemotherapy. A vast response rate interval and a short survival rate indicate that the efficacy and efficiency of the selection of chemotherapy have not been optimized. This article aims to illustrate the potential relationship of various genetic polymorphisms in response to platinum-based chemotherapy for several types of cancer. This review was conducted using articles from the last three- and five-year periods (2014-2019) that use gene polymorphism and its relationship to the efficacy of platinum-based chemotherapy as their theme. A total of 26 out of 488 relevant articles were included based on specific criteria. Through various mechanisms, genes, including ERCC1, ERCC2/XPD, XPC, XPA, XRCC1, APE-1, PARP1, OGG1, ABCC2, MRP, GSTP1, GSTM1, GSTT1, MATE1, and OCT2, have been associated with patient response to platinum-based chemotherapy. We conclude that genetic polymorphism analysis is recommended for the management of cancer so that each patient can be administered therapy based on his or her genetic profile to achieve an effective and efficient outcome.
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Affiliation(s)
- Nadiya Nurul Afifah
- Department of Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, Universitas Padjadjaran, Bandung, Indonesia
| | - Ajeng Diantini
- Department of Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, Universitas Padjadjaran, Bandung, Indonesia
- Center of Excellence in Higher Education for Pharmaceutical Care Innovation, Universitas Padjadjaran, Bandung, Indonesia
| | - Ruri Intania
- Dr. H.A. Rotinsulu Lung Hospital, Bandung, Indonesia
| | - Rizky Abdulah
- Department of Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, Universitas Padjadjaran, Bandung, Indonesia
- Center of Excellence in Higher Education for Pharmaceutical Care Innovation, Universitas Padjadjaran, Bandung, Indonesia
| | - Melisa I Barliana
- Center of Excellence in Higher Education for Pharmaceutical Care Innovation, Universitas Padjadjaran, Bandung, Indonesia
- Department of Biological Pharmacy, Faculty of Pharmacy, Universitas Padjadjaran, Bandung, Indonesia
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Synthesis and characterization of butylamine-functionalized Cr(III)–MOF–SO3H: Synergistic effect of the hydrophobic moiety on Cr(III)–MOF–SO3H in esterification reactions. Polyhedron 2019. [DOI: 10.1016/j.poly.2019.114142] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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5
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Abstract
Similar to many other biological molecules, RNA is vulnerable to chemical insults from endogenous and exogenous sources. Noxious agents such as reactive oxygen species or alkylating chemicals have the potential to profoundly affect the chemical properties and hence the function of RNA molecules in the cell. Given the central role of RNA in many fundamental biological processes, including translation and splicing, changes to its chemical composition can have a detrimental impact on cellular fitness, with some evidence suggesting that RNA damage has roles in diseases such as neurodegenerative disorders. We are only just beginning to learn about how cells cope with RNA damage, with recent studies revealing the existence of quality-control processes that are capable of recognizing and degrading or repairing damaged RNA. Here, we begin by reviewing the most abundant types of chemical damage to RNA, including oxidation and alkylation. Focusing on mRNA damage, we then discuss how alterations to this species of RNA affect its function and how cells respond to these challenges to maintain proteostasis. Finally, we briefly discuss how chemical damage to noncoding RNAs such as rRNA, tRNA, small nuclear RNA, and small nucleolar RNA is likely to affect their function.
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Affiliation(s)
- Liewei L. Yan
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri 63130
| | - Hani S. Zaher
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri 63130, To whom correspondence should be addressed:
Dept. of Biology, Washington University in St. Louis, Campus Box 1137, One Brookings Dr., St. Louis, MO 63130. Tel.:
314-935-7662; Fax:
314-935-4432; E-mail:
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6
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Electrocatalytic deiodination of methyl iodide on a copper electrode. RESEARCH ON CHEMICAL INTERMEDIATES 2019. [DOI: 10.1007/s11164-019-03817-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Ray PC, Pawar YD, Singare DT, Deshpande TN, Singh GP. Novel Process for Preparation of Tetrabenazine and Deutetrabenazine. Org Process Res Dev 2018. [DOI: 10.1021/acs.oprd.8b00011] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Purna Chandra Ray
- Lupin Research Park, Lupin Limited, 46 & 47A, Village Nande, Taluka Mulshi, Pune-412115, Maharashtra, India
| | - Yogesh Dadaji Pawar
- Lupin Research Park, Lupin Limited, 46 & 47A, Village Nande, Taluka Mulshi, Pune-412115, Maharashtra, India
| | | | - Tushar Nandkumar Deshpande
- Lupin Research Park, Lupin Limited, 46 & 47A, Village Nande, Taluka Mulshi, Pune-412115, Maharashtra, India
| | - Girij Pal Singh
- Lupin Research Park, Lupin Limited, 46 & 47A, Village Nande, Taluka Mulshi, Pune-412115, Maharashtra, India
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9
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Szekely G, Amores de Sousa MC, Gil M, Castelo Ferreira F, Heggie W. Genotoxic Impurities in Pharmaceutical Manufacturing: Sources, Regulations, and Mitigation. Chem Rev 2015; 115:8182-229. [DOI: 10.1021/cr300095f] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Gyorgy Szekely
- School of Chemical Engineering & Analytical Science, The University of Manchester, The Mill, Sackville Street, Manchester M13 9PL, United Kingdom
| | - Miriam C. Amores de Sousa
- Department
of Bioengineering and Institute for Bioengineering and Biosciences
(iBB), Instituto Superior Técnico, Universidade de Lisboa, Avenida Rovisco Pais, 1049-001, Lisbon, Portugal
| | - Marco Gil
- Hovione FarmaCiencia SA, R&D, Sete Casas, 2674-506, Loures, Portugal
| | - Frederico Castelo Ferreira
- Department
of Bioengineering and Institute for Bioengineering and Biosciences
(iBB), Instituto Superior Técnico, Universidade de Lisboa, Avenida Rovisco Pais, 1049-001, Lisbon, Portugal
| | - William Heggie
- Hovione FarmaCiencia SA, R&D, Sete Casas, 2674-506, Loures, Portugal
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Kloth S, Baur X, Göen T, Budnik LT. Accidental exposure to gas emissions from transit goods treated for pest control. Environ Health 2014; 13:110. [PMID: 25495528 PMCID: PMC4320564 DOI: 10.1186/1476-069x-13-110] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 11/26/2014] [Indexed: 06/04/2023]
Abstract
BACKGROUND International phytosanitary standards ISPM 15 require (since 2007) fumigation or heat treatment for shipping and storage. Those dealing with fumigated freight might be accidentally exposed. In this paper we report a series of three accidents of six storage room workers in a medium sized company regularly importing electronic production parts from abroad. METHODS Patients (n=6, aged from 32-54 yrs.) and control group (n=30, mean 40 yrs.) donated blood and urine samples. The fumigants: ethylene oxide, methyl bromide, chloropicrin, ethylene dichloride, other halo-alkanes and solvents were analyzed by headspace gas chromatography/mass spectrometry (GCMS). For the quantitation of long term exposure/s, macromolecular reaction products (hemoglobin adducts) were used (with GCMS) as molecular dosimeter; additionally 8-OHdG and circulating mtDNA (cmtDNA) were analyzed as nonspecific biological effect markers. RESULTS The hemoglobin adducts N-methyl valine (MEV) and N-(2-hydroxy ethyl) valine (HEV) were elevated after exposure to the alkylating chemicals methyl bromide and ethylene oxide. Under the consideration of known elimination kinetics and the individual smoking status (biomonitored with nicotine metabolite cotinine and tobacco specific hemoglobin adduct: N-(2 cyan ethyl) valines, CEV), the data allow theoretical extrapolation to the initial protein adduct concentrations at the time of the accident (the MEV/CEV levels were from 1,616 pmol/g globin to 1,880 pmol/g globin and HEV/CEV levels from 1,407 pmol/g globin to 5,049 pmol/g globin, and correlated with inhaled 0.4-1.5 ppm ethylene oxide. These integrated, extrapolated internal doses, calculated on the basis of biological exposure equivalents, confirmed the clinical diagnosis for three patients, showing severe intoxication symptoms. Both, cmtDNA and 8-OHdG, as non-specific biomarkers of toxic effects, were elevated in four patients. CONCLUSION The cases reported here, stress the importance of a suitable risk assessment and control measures. We put emphasis on the necessity of human biomonitoring guidelines and the urgency for the relevant limit values.
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Affiliation(s)
- Stefan Kloth
- />Division of Occupational Toxicology and Immunology, Institute for Occupational and Maritime Medicine (ZfAM), University Medical Center Hamburg-Eppendorf, University of Hamburg, Marckmannstrasse 129 b, Bld. 3, 20539 Hamburg, Germany
- />Robert Koch Institute, Unit Strengthening Global Biosecurity, Berlin, Germany
| | - Xaver Baur
- />Institute for Occupational Medicine, Campus Benjamin Franklin, Charité-School of Medicine, Berlin, Germany
| | - Thomas Göen
- />Institute and Outpatient Clinic of Occupational, Social and Environmental Medicine, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Lygia Therese Budnik
- />Division of Occupational Toxicology and Immunology, Institute for Occupational and Maritime Medicine (ZfAM), University Medical Center Hamburg-Eppendorf, University of Hamburg, Marckmannstrasse 129 b, Bld. 3, 20539 Hamburg, Germany
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Dawar P, Raju MB, Ramakrishna RA. One-Pot Esterification and Amide Formation via Acid-Catalyzed Dehydration and Ritter Reactions. SYNTHETIC COMMUN 2014. [DOI: 10.1080/00397911.2013.837485] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Xuan R, Ashworth DJ, Wu L, Yates SR. Mitigating iodomethane emissions and iodide residues in fumigated soils. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:13047-13052. [PMID: 24151978 DOI: 10.1021/es403954z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Although long-regarded as an excellent soil fumigant for killing plant pests, methyl bromide (MeBr) was phased out in 2005 in the USA, because it can deplete the stratospheric ozone layer. Iodomethane (MeI) has been identified as an effective alternative to MeBr and is used in a number of countries for preplant pest control. However, MeI is highly volatile and potentially carcinogenic to humans if inhaled. In addition, iodide anions, a breakdown product of MeI, can build up in fumigated soils and potentially cause plant toxicity and contaminate groundwater via leaching. In order to overcome the above two obstacles in MeI application, a method is proposed to place reactive bags containing ammonium hydroxide solution (NH4OH) on the soil surface underneath an impermeable plastic film covering the fumigated area. Our research showed that using this approach, over 99% of the applied MeI was quantitatively transferred to iodide. Of all the resulting iodide, only 2.7% remained in the fumigated soil, and 97.3% was contained in the reactive bag that can be easily removed after fumigation.
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Affiliation(s)
- Richeng Xuan
- USDA-ARS, Salinity Laboratory, 450 West Big Springs Road, Riverside, California 92507, United States
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13
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Abstract
Methyl bromide (MeBr) is a chemically reactive compound that has found use as a fire retardant and fumigant used for wood, soil, fruits and grains. Its use is banned in many countries because of its ozone-depleting properties. Despite this ban, the use of MeBr persists in some parts of the world (e.g. New Zealand) due to its important role in maintaining strict biosecurity of exported and imported products. Its high chemical reactivity leads to a broad toxicological profile ranging from acute respiratory toxicity following inhalation exposure, through carcinogenicity to neurotoxicty. In this article, we discuss the chemistry of MeBr in the context of its mechanisms of toxicity. The chemical reactivity of MeBr clearly underlies its toxicity. Bromine (Br) is electronegative and a good leaving group; the δ+ carbon thus facilitates electrophilic methylation of biological molecules including glutathione (GSH) via its δ- sulphur atom, leading to downstream effects due to GSH depletion. DNA alkylation, either directly by MeBr or indirectly due to reduction in GSH-mediated detoxification of reactive alkylating chemical species, might explain the carcinogenicity of MeBr. The neurotoxicity of MeBr is much more difficult to understand, but we speculate that methyl phosphates formed in cells might contribute to its neurone-specific toxicity via cholinesterase inhibition. Finally, evidence reviewed shows that it is unlikely for Br⁻ liberated by the metabolism of MeBr to have any toxicological effect because the Br⁻ dose is very low.
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Affiliation(s)
- A T Bulathsinghala
- Department of Chemistry, University of Canterbury, Christchurch, New Zealand
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14
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Budnik LT, Kloth S, Baur X, Preisser AM, Schwarzenbach H. Circulating mitochondrial DNA as biomarker linking environmental chemical exposure to early preclinical lesions elevation of mtDNA in human serum after exposure to carcinogenic halo-alkane-based pesticides. PLoS One 2013; 8:e64413. [PMID: 23741329 PMCID: PMC3669318 DOI: 10.1371/journal.pone.0064413] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 04/14/2013] [Indexed: 01/05/2023] Open
Abstract
There is a need for a panel of suitable biomarkers for detection of environmental chemical exposure leading to the initiation or progression of degenerative diseases or potentially, to cancer. As the peripheral blood may contain increased levels of circulating cell-free DNA in diseased individuals, we aimed to evaluate this DNA as effect biomarker recognizing vulnerability after exposure to environmental chemicals. We recruited 164 individuals presumably exposed to halo-alkane-based pesticides. Exposure evaluation was based on human biomonitoring analysis; as biomarker of exposure parent halo-methanes, -ethanes and their metabolites, as well as the hemoglobin-adducts methyl valine and hydroxyl ethyl valine in blood were used, complemented by expert evaluation of exposure and clinical intoxication symptoms as well as a questionnaire. Assessment showed exposures to halo alkanes in the concentration range being higher than non-cancer reference doses (RfD) but (mostly) lower than the occupational exposure limits. We quantified circulating DNA in serum from 86 individuals with confirmed exposure to off-gassing halo-alkane pesticides (in storage facilities or in home environment) and 30 non-exposed controls, and found that exposure was significantly associated with elevated serum levels of circulating mitochondrial DNA (in size of 79 bp, mtDNA-79, p = 0.0001). The decreased integrity of mtDNA (mtDNA-230/mtDNA-79) in exposed individuals implicates apoptotic processes (p = 0.015). The relative amounts of mtDNA-79 in serum were positively associated with the lag-time after intoxication to these chemicals (r = 0.99, p<0.0001). Several months of post-exposure the specificity of this biomarker increased from 30% to 97% in patients with intoxication symptoms. Our findings indicate that mitochondrial DNA has a potential to serve as a biomarker recognizing vulnerable risk groups after exposure to toxic/carcinogenic chemicals.
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Affiliation(s)
- Lygia T Budnik
- Institute for Occupational and Maritime Medicine, Department of Occupational Health, School of Medicine, University of Hamburg, Hamburg, Germany.
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15
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Alavanja MCR, Ross MK, Bonner MR. Increased cancer burden among pesticide applicators and others due to pesticide exposure. CA Cancer J Clin 2013; 63:120-42. [PMID: 23322675 DOI: 10.3322/caac.21170] [Citation(s) in RCA: 187] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
A growing number of well-designed epidemiological and molecular studies provide substantial evidence that the pesticides used in agricultural, commercial, and home and garden applications are associated with excess cancer risk. This risk is associated both with those applying the pesticide and, under some conditions, those who are simply bystanders to the application. In this article, the epidemiological, molecular biology, and toxicological evidence emerging from recent literature assessing the link between specific pesticides and several cancers including prostate cancer, non-Hodgkin lymphoma, leukemia, multiple myeloma, and breast cancer are integrated. Although the review is not exhaustive in its scope or depth, the literature does strongly suggest that the public health problem is real. If we are to avoid the introduction of harmful chemicals into the environment in the future, the integrated efforts of molecular biology, pesticide toxicology, and epidemiology are needed to help identify the human carcinogens and thereby improve our understanding of human carcinogenicity and reduce cancer risk.
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Affiliation(s)
- Michael C R Alavanja
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, North Bethesda, MD 20892, USA.
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Horng YC, Huang PS, Hsieh CC, Kuo CH, Kuo TS. Selective encapsulation of volatile and reactive methyl iodide. Chem Commun (Camb) 2012; 48:8844-6. [PMID: 22842553 DOI: 10.1039/c2cc34346k] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
A simple organic molecular container can selectively encapsulate the volatile and highly reactive MeI through hydrogen-bonding interactions in solution. The remarkable encapsulation of MeI without self-methylation of the container appears to be determined by the complementary binding sites and the rigidity of the hydrogen-bonding array constrained by the molecular framework.
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Affiliation(s)
- Yih-Chern Horng
- Department of Chemistry, National Changhua University of Education, 1 Jin-De Road, Changhua 50058, Taiwan.
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Kar S, Roy K. First report on development of quantitative interspecies structure-carcinogenicity relationship models and exploring discriminatory features for rodent carcinogenicity of diverse organic chemicals using OECD guidelines. CHEMOSPHERE 2012; 87:339-355. [PMID: 22225702 DOI: 10.1016/j.chemosphere.2011.12.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2011] [Revised: 12/08/2011] [Accepted: 12/08/2011] [Indexed: 05/31/2023]
Abstract
Different regulatory agencies in food and drug administration and environmental protection worldwide are employing quantitative structure-activity relationship (QSAR) models to fill the data gaps related with properties of chemicals affecting the environment and human health. Carcinogenicity is a toxicity endpoint of major concern in recent times. Interspecies toxicity correlations may provide a tool for estimating sensitivity towards toxic chemical exposure with known levels of uncertainty for a diversity of wildlife species. In this background, we have developed quantitative interspecies structure-carcinogenicity correlation models for rat and mouse [rodent species according to the Organization for Economic Cooperation and Development (OECD) guidelines] based on the carcinogenic potential of 166 organic chemicals with wide diversity of molecular structures, spanning a large number of chemical classes and biological mechanisms. All the developed models have been assessed according to the OECD principles for the validation of QSAR models. Consensus predictions for carcinogenicity of the individual compounds are presented here for any one species when the data for the other species are available. Informative illustrations of the contributing structural fragments of chemicals which are responsible for specific carcinogenicity endpoints are identified by the developed models. The models have also been used to predict mouse carcinogenicities of 247 organic chemicals (for which rat carcinogenicities are present) and rat carcinogenicities of 150 chemicals (for which mouse carcinogenicities are present). Discriminatory features for rat and mouse carcinogenicity values have also been explored.
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Affiliation(s)
- Supratik Kar
- Drug Theoretics and Cheminformatics Laboratory, Department of Pharmaceutical Technology, Jadavpur University, Kolkata 700 032, India
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Glaser R, Prugger K. Iodine bonding stabilizes iodomethane in MIDAS pesticide. Theoretical study of intermolecular interactions between iodomethane and chloropicrin. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2012; 60:1776-1787. [PMID: 22313191 DOI: 10.1021/jf2037906] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The results are reported of a theoretical study of iodomethane (H(3)C-I, 1) and chloropicrin (Cl(3)C-NO(2), 2), of the heterodimers 3-6 formed by aggregation of 1 and 2, and of their addition products 7 and 8 and their possible fragmentation reactions to 9-18. Mixtures of iodomethane and chloropicrin are not expected to show chemistry resulting from their reactions with each other. The structures and stabilities are discussed of the iodine-bonded molecular aggregates (IBMA) 3 and 4 and of the hydrogen- and iodine-bonded molecular aggregates (IHBMA) 5 and 6. The mixed aggregates 3-5 are bound on the free enthalpy surface relative to the homodimers of 1 and 2, and the IBMA structures 3 and 4 are most stable. This result suggests that the mixture of chloropicrin and iodomethane in the pesticide Midas is a good choice to reduce the volatility of iodomethane because of thermodynamically stabilizing iodine bonding.
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Affiliation(s)
- Rainer Glaser
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, United States.
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19
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Budnik LT, Kloth S, Velasco-Garrido M, Baur X. Prostate cancer and toxicity from critical use exemptions of methyl bromide: environmental protection helps protect against human health risks. Environ Health 2012; 11:5. [PMID: 22284215 PMCID: PMC3807750 DOI: 10.1186/1476-069x-11-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Accepted: 01/27/2012] [Indexed: 05/29/2023]
Abstract
BACKGROUND Although ozone-depleting methyl bromide was destined for phase-out by 2005, it is still widely applied as a consequence of various critical-use-exemptions and mandatory international regulations aiming to restrict the spread of pests and alien species (e.g. in globalized transport and storage). The withdrawal of methyl bromide because of its environmental risk could fortuitously help in the containment of its human toxicity. METHODS We performed a systematic review of the literature, including in vitro toxicological and epidemiological studies of occupational and community exposure to the halogenated hydrocarbon pesticide methyl bromide. We focused on toxic (especially chronic) or carcinogenic effects from the use of methyl bromide, on biomonitoring data and reference values. Eligible epidemiological studies were subjected to meta-analysis. RESULTS Out of the 542 peer reviewed publications between 1990-2011, we found only 91 referring to toxicity of methyl bromide and 29 using the term "carcinogenic", "neoplastic" or "mutagenic". Several studies provide new additional data pertaining to the mechanistic aspects of methyl bromide toxicity. Few studies have performed a detailed exposure assessment including biomonitoring. Three evaluated epidemiological studies assessed a possible association between cancer and methyl bromide. Overall, exposure to methyl bromide is associated with an increased risk of prostate cancer OR, 1.21; 95% CI (0,98-1.49), P = 0.076. Two epidemiological studies have analyzed environmental, non-occupational exposure to methyl bromide providing evidence for its health risk to the general public. None of the epidemiological studies addressed its use as a fumigant in freight containers, although recent field and case reports do refer to its toxic effects associated with its use in shipping and storage. CONCLUSIONS Both the epidemiological evidence and toxicological data suggest a possible link between methyl bromide exposure and serious health problems, including prostate cancer risk from occupational and community exposure. The environmental risks of methyl bromide are not in doubt, but also its health risks, especially for genetically predisposed subjects, should not be underestimated.
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Affiliation(s)
- Lygia T Budnik
- Division of Occupational Toxicology and Immunology, Institute for Occupational and Maritime Medicine (ZfAM), Medical Faculty, University of Hamburg, University Medical Center, Hamburg, Germany
| | - Stefan Kloth
- Division of Occupational Toxicology and Immunology, Institute for Occupational and Maritime Medicine (ZfAM), Medical Faculty, University of Hamburg, University Medical Center, Hamburg, Germany
| | - Marcial Velasco-Garrido
- Division of Clinical Occupational Medicine, Institute for Occupational and Maritime Medicine (ZfAM), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Xaver Baur
- Chair for Occupational Medicine, Medical Faculty, University of Hamburg, University Medical Center, Hamburg, Germany
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Abstract
Methyl iodide is a monohalomethane and with a chemical formula CH(3)I. Acute exposures to methyl iodide have frequently occurred in the workplace. Predominantly, neuropsychiatric symptoms of acute exposure to monohalomethanes consist of headache, nausea, vomiting, drowsiness, dizziness, giddiness, diarrhea, confusion, ataxia, slurred speech, paralysis, convulsions, delirium, coma, and death. We report two cases who presented to our emergency services after accidental exposure to methyl iodide for a short duration. These case reports highlighted concurrence of frankly psychotic features and acute confusional state in workers vulnerable to industrial exposure to toxic chemicals. Understanding the mechanism of neuro-toxicity will perhaps throw some light on co-existence of both psychiatric and neurological symptoms. Awareness of these toxic effects at vulnerable work places will lead to timely and appropriate interventions. Importance of safety precautions and education of both workers and supervisors cannot be overemphasized here.
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Affiliation(s)
| | - Tushita S. Mayanil
- Department of Psychiatry, Seth G.S.M.C. & K.E.M. Hospital, Mumbai, India
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One-pot esterification and Ritter reaction: chemo- and regioselectivity from tert-butyl methyl ether. Tetrahedron Lett 2011. [DOI: 10.1016/j.tetlet.2011.04.100] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Benigni R, Bossa C. Mechanisms of Chemical Carcinogenicity and Mutagenicity: A Review with Implications for Predictive Toxicology. Chem Rev 2011; 111:2507-36. [PMID: 21265518 DOI: 10.1021/cr100222q] [Citation(s) in RCA: 239] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Romualdo Benigni
- Istituto Superiore di Sanita’, Environment and Health Department, Viale Regina Elena, 299 00161 Rome, Italy
| | - Cecilia Bossa
- Istituto Superiore di Sanita’, Environment and Health Department, Viale Regina Elena, 299 00161 Rome, Italy
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Maraš N, Polanc S, Kočevar M. Microwave-assisted methylation of phenols with tetramethylammonium chloride in the presence of K2CO3 or Cs2CO3. Tetrahedron 2008. [DOI: 10.1016/j.tet.2008.10.024] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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24
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Juárez R, Padilla A, Corma A, García H. Organocatalysts for the Reaction of Dimethyl Carbonate with 2,4-Diaminotoluene. Ind Eng Chem Res 2008. [DOI: 10.1021/ie800126t] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Raquel Juárez
- Instituto de Tecnología Química CSIC-UPV, Universidad Politécnica de Valencia, Avda. de los Naranjos, 46022 Valencia, Spain, and Centro Tecnológico de Repsol YPF, Crta. De Extremadura, Km 18, 28931 Madrid, Spain
| | - Ana Padilla
- Instituto de Tecnología Química CSIC-UPV, Universidad Politécnica de Valencia, Avda. de los Naranjos, 46022 Valencia, Spain, and Centro Tecnológico de Repsol YPF, Crta. De Extremadura, Km 18, 28931 Madrid, Spain
| | - Avelino Corma
- Instituto de Tecnología Química CSIC-UPV, Universidad Politécnica de Valencia, Avda. de los Naranjos, 46022 Valencia, Spain, and Centro Tecnológico de Repsol YPF, Crta. De Extremadura, Km 18, 28931 Madrid, Spain
| | - Hermenegildo García
- Instituto de Tecnología Química CSIC-UPV, Universidad Politécnica de Valencia, Avda. de los Naranjos, 46022 Valencia, Spain, and Centro Tecnológico de Repsol YPF, Crta. De Extremadura, Km 18, 28931 Madrid, Spain
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Gargas ML, Sweeney LM, Himmelstein MW, Pottenger LH, Bus JS, Holder JW. Physiologically based Pharmacokinetic Modeling of Chloroethane Disposition in Mice, Rats, and Women. Toxicol Sci 2008; 104:54-66. [DOI: 10.1093/toxsci/kfn064] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Kirman CR, Sweeney LM, Gargas ML, Kinzell JH. Evaluation of possible modes of action for acute effects of methyl iodide in laboratory animals. Inhal Toxicol 2008; 21:537-51. [DOI: 10.1080/08958370802601510] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Watanabe K, Liberman RG, Skipper PL, Tannenbaum SR, Guengerich FP. Analysis of DNA adducts formed in vivo in rats and mice from 1,2-dibromoethane, 1,2-dichloroethane, dibromomethane, and dichloromethane using HPLC/accelerator mass spectrometry and relevance to risk estimates. Chem Res Toxicol 2007; 20:1594-600. [PMID: 17907789 DOI: 10.1021/tx700125p] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Dihaloalkanes are of toxicological interest because of their high-volume use in industry and their abilities to cause tumors in rodents, particularly dichloromethane and 1,2-dichloroethane. The brominated analogues are not used as extensively but are known to produce more toxicity in some systems. Rats and mice were treated i.p. with (14)C-dichloromethane, -dibromomethane, -1,2-dichloroethane, or -1,2-dibromoethane [5 mg (kg body weight)(-1)], and livers and kidneys were collected to rapidly isolate DNA. The DNA was digested using a procedure designed to minimize processing time, because some of the potential dihalomethane-derived DNA-glutathione (GSH) adducts are known to be unstable, and the HPLC fractions corresponding to major adduct standards were separated and analyzed for (14)C using accelerator mass spectrometry. The level of liver or kidney S-[2-(N(7)-guanyl)ethyl]GSH in rats treated with 1,2-dibromoethane was approximately 1 adduct/10(5) DNA bases; in male or female mice, the level was approximately one-half of this. The levels of 1,2-dichloroethane adducts were 10-50-fold lower. None of four known (in vitro) GSH-DNA adducts was detected at a level of >2/10(8) DNA bases from dibromomethane or dichloromethane. These results provide parameters for risk assessment of these compounds: DNA binding occurs with 1,2-dichloroethane but is considerably less than from 1,2-dibromoethane in vivo, and low exposure to dihalomethanes does not produce appreciable DNA adduct levels in rat or mouse liver and kidney of the doses used. The results may be used to address issues in human risk assessment.
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Affiliation(s)
- Kengo Watanabe
- Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
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Del Bigio MR, Halliday WC. Multifocal atrophy of cerebellar internal granular neurons in lesch-nyhan disease: case reports and review. J Neuropathol Exp Neurol 2007; 66:346-53. [PMID: 17483691 DOI: 10.1097/nen.0b013e3180515319] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The neuropathologic findings in 31 cases (aged 6 months to 33 years) of Lesch-Nyhan disease (hypoxanthine-guanine phosphoribosyltransferase deficiency) have been previously reported. Herein 2 additional cases, a 10-year-old boy and a 21-year-old man, are described. Both cases had unusual cerebellar abnormalities comprising multifocal internal granular layer atrophy with sparing of the Purkinje layer, one had a slightly small brain, and neither had striatal abnormalities. Careful review of the literature indicates that the most prevalent neuropathologic abnormalities are small cerebrum (13 of 33 cases) and multifocal cerebellar lesions (9 of 33 cases), although these could be underreported. Other authors have disregarded these abnormalities, focusing on the apparently normal basal nuclei, and they have suggested that the clinical neurologic abnormalities are based solely on changes in neurotransmitters. We discuss potential mechanisms of cerebellar damage, suggest that the cerebellar abnormality could in part explain the clinical syndrome, and recommend that cerebellar structure and function should be more carefully studied in Lesch-Nyhan disease.
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Affiliation(s)
- Marc R Del Bigio
- Department of Pathology, University of Manitoba, Winnipeg, Canada.
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Tal S, Salman H, Abraham Y, Botoshansky M, Eichen Y. Sensitive and Selective Photoinduced-Electron-Transfer-Based Sensing of Alkylating Agents. Chemistry 2006; 12:4858-64. [PMID: 16598802 DOI: 10.1002/chem.200501332] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Photoinduced-electron-transfer (PET)-based chemosensing is a very elegant way of reporting the presence of a guest species in solution. This method was successfully applied for the detection of different ionic species, such as cations, anions, and protons. Herein, we report on the application of the PET chemosensing concept for the efficient and selective detection of different alkylating agents. 2-(2-Dimethylaminoethyl)benzo[de]isoquinoline-1,3-dione (1) was found to be a highly selective and effective PET chemosensor that turns luminescent upon reacting with different alkylating agents. This PET-based system detected even rather weak alkylating agents, such as dichloromethane. A PET-based sensor that consists of 1 as the active component could detect rather low concentrations of alkylating agents in solution and in the gas phase.
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Affiliation(s)
- Shay Tal
- Department of Chemistry, Technion-Israel Institute of Technology, Technion City, 32000, Haifa, Israel.
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Lambert IB, Singer TM, Boucher SE, Douglas GR. Detailed review of transgenic rodent mutation assays. Mutat Res 2005; 590:1-280. [PMID: 16081315 DOI: 10.1016/j.mrrev.2005.04.002] [Citation(s) in RCA: 252] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2005] [Revised: 04/04/2005] [Accepted: 04/12/2005] [Indexed: 11/17/2022]
Abstract
Induced chromosomal and gene mutations play a role in carcinogenesis and may be involved in the production of birth defects and other disease conditions. While it is widely accepted that in vivo mutation assays are more relevant to the human condition than are in vitro assays, our ability to evaluate mutagenesis in vivo in a broad range of tissues has historically been quite limited. The development of transgenic rodent (TGR) mutation models has given us the ability to detect, quantify, and sequence mutations in a range of somatic and germ cells. This document provides a comprehensive review of the TGR mutation assay literature and assesses the potential use of these assays in a regulatory context. The information is arranged as follows. (1) TGR mutagenicity models and their use for the analysis of gene and chromosomal mutation are fully described. (2) The principles underlying current OECD tests for the assessment of genotoxicity in vitro and in vivo, and also nontransgenic assays available for assessment of gene mutation, are described. (3) All available information pertaining to the conduct of TGR assays and important parameters of assay performance have been tabulated and analyzed. (4) The performance of TGR assays, both in isolation and as part of a battery of in vitro and in vivo short-term genotoxicity tests, in predicting carcinogenicity is described. (5) Recommendations are made regarding the experimental parameters for TGR assays, and the use of TGR assays in a regulatory context.
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Affiliation(s)
- Iain B Lambert
- Mutagenesis Section, Environmental Health Sciences Bureau, Healthy Environments and Consumer Safety Branch, 0803A, Health Canada, Ottawa, Ont., Canada K1A 0L2.
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Schwartz MD, Obamwonyi AO, Thomas JD, Moorhead JF, Morgan BW. Acute methyl iodide exposure with delayed neuropsychiatric sequelae: report of a case. Am J Ind Med 2005; 47:550-6. [PMID: 15898088 DOI: 10.1002/ajim.20169] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Methyl iodide is a monohalomethane used as an analytic and organic chemistry reagent, as a methylating agent in organic chemical synthesis, and as a fumigant. In an acute exposure, methyl iodide is a pulmonary and dermal irritant. Chronic neurotoxicity has been reported in survivors of acute exposure. METHODS A review of the 11 case reports of methyl iodide poisoning in the medical literature of the 20th century found that six of the patients experienced a chronic neurological syndrome characterized primarily by delayed psychiatric, behavioral, and cognitive sequelae. RESULTS The case patient experienced a massive exposure to methyl iodide with resulting life-threatening burns. During convalescence, various cognitive and behavioral deficits became apparent. The results of a comprehensive evaluation at our occupational toxicology clinic, which included sequential neuropsychometric testing, are described. CONCLUSION The findings in the case patient may advance our understanding of the mechanisms and clinical manifestations of chronic neurotoxicity after exposure to methyl iodide.
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Affiliation(s)
- Michael D Schwartz
- Department of Emergency Medicine, Georgia Poison Center/Emory University, Atlanta, Georgia 30333, USA.
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Drabløs F, Feyzi E, Aas PA, Vaagbø CB, Kavli B, Bratlie MS, Peña-Diaz J, Otterlei M, Slupphaug G, Krokan HE. Alkylation damage in DNA and RNA--repair mechanisms and medical significance. DNA Repair (Amst) 2005; 3:1389-407. [PMID: 15380096 DOI: 10.1016/j.dnarep.2004.05.004] [Citation(s) in RCA: 443] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2004] [Indexed: 12/13/2022]
Abstract
Alkylation lesions in DNA and RNA result from endogenous compounds, environmental agents and alkylating drugs. Simple methylating agents, e.g. methylnitrosourea, tobacco-specific nitrosamines and drugs like temozolomide or streptozotocin, form adducts at N- and O-atoms in DNA bases. These lesions are mainly repaired by direct base repair, base excision repair, and to some extent by nucleotide excision repair (NER). The identified carcinogenicity of O(6)-methylguanine (O(6)-meG) is largely caused by its miscoding properties. Mutations from this lesion are prevented by O(6)-alkylG-DNA alkyltransferase (MGMT or AGT) that repairs the base in one step. However, the genotoxicity and cytotoxicity of O(6)-meG is mainly due to recognition of O(6)-meG/T (or C) mispairs by the mismatch repair system (MMR) and induction of futile repair cycles, eventually resulting in cytotoxic double-strand breaks. Therefore, inactivation of the MMR system in an AGT-defective background causes resistance to the killing effects of O(6)-alkylating agents, but not to the mutagenic effect. Bifunctional alkylating agents, such as chlorambucil or carmustine (BCNU), are commonly used anti-cancer drugs. DNA lesions caused by these agents are complex and require complex repair mechanisms. Thus, primary chloroethyl adducts at O(6)-G are repaired by AGT, while the secondary highly cytotoxic interstrand cross-links (ICLs) require nucleotide excision repair factors (e.g. XPF-ERCC1) for incision and homologous recombination to complete repair. Recently, Escherichia coli protein AlkB and human homologues were shown to be oxidative demethylases that repair cytotoxic 1-methyladenine (1-meA) and 3-methylcytosine (3-meC) residues. Numerous AlkB homologues are found in viruses, bacteria and eukaryotes, including eight human homologues (hABH1-8). These have distinct locations in subcellular compartments and their functions are only starting to become understood. Surprisingly, AlkB and hABH3 also repair RNA. An evaluation of the biological effects of environmental mutagens, as well as understanding the mechanism of action and resistance to alkylating drugs require a detailed understanding of DNA repair processes.
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Affiliation(s)
- Finn Drabløs
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, N-7489 Trondheim, Norway
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Fonnum F, Lock EA. The contributions of excitotoxicity, glutathione depletion and DNA repair in chemically induced injury to neurones: exemplified with toxic effects on cerebellar granule cells. J Neurochem 2004; 88:513-31. [PMID: 14720201 DOI: 10.1046/j.1471-4159.2003.02211.x] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Six chemicals, 2-halopropionic acids, thiophene, methylhalides, methylmercury, methylazoxymethanol (MAM) and trichlorfon (Fig. 1), that cause selective necrosis to the cerebellum, in particular to cerebellar granule cells, have been reviewed. The basis for the selective toxicity to these neurones is not fully understood, but mechanisms known to contribute to the neuronal cell death are discussed. All six compounds decrease cerebral glutathione (GSH), due to conjugation with the xenobiotic, thereby reducing cellular antioxidant status and making the cells more vulnerable to reactive oxygen species. 2-Halopropionic acids and methylmercury appear to also act via an excitotoxic mechanism leading to elevated intracellular Ca2+, increased reactive oxygen species and ultimately impaired mitochondrial function. In contrast, the methylhalides, trichlorfon and MAM all methylate DNA and inhibit O6-guanine-DNA methyltransferase (OGMT), an important DNA repair enzyme. We propose that a combination of reduced antioxidant status plus excitotoxicity or DNA damage is required to cause cerebellar neuronal cell death with these chemicals. The small size of cerebellar granule cells, the unique subunit composition of their N-methyl-d-aspartate (NMDA) receptors, their low DNA repair ability, low levels of calcium-binding proteins and vulnerability during postnatal brain development and distribution of glutathione and its conjugating and metabolizing enzymes are all important factors in determining the sensitivity of cerebellar granule cells to toxic compounds.
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Affiliation(s)
- F Fonnum
- Norwegian Defence Research Establishment, Division for Protection and Material, Kjeller, Norway.
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Thier R, Brüning T, Roos PH, Rihs HP, Golka K, Ko Y, Bolt HM. Markers of genetic susceptibility in human environmental hygiene and toxicology: the role of selected CYP, NAT and GST genes. Int J Hyg Environ Health 2003; 206:149-71. [PMID: 12872524 DOI: 10.1078/1438-4639-00209] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Inherited genetic traits co-determine the susceptibility of an individual to a toxic chemical. Special emphasis has been put on individual responses to environmental and industrial carcinogens, but other chronic diseases are of increasing interest. Polymorphisms of relevant xenobiotic metabolising enzymes may be used as toxicological susceptibility markers. A growing number of genes encoding enzymes involved in biotransformation of toxicants and in cellular defence against toxicant-induced damage to the cells has been identified and cloned, leading to increased knowledge of allelic variants of genes and genetic defects that may result in a differential susceptibility toward environmental toxicants. "Low penetrating" polymorphisms in metabolism genes tend to be much more common in the population than allelic variants of "high penetrating" cancer genes, and are therefore of considerable importance from a public health point of view. Positive associations between cancer and CYP1A1 alleles, in particular the *2C I462V allele, were found for tissues following the aerodigestive tract. Again, in most cases, the effect of the variant CYP1A1 allele becomes apparent or clearer in connection with the GSTM1 null allele. The CYP1B1 codon 432 polymorphism (CYP1B1*3) has been identified as a susceptibility factor in smoking-related head-and-neck squameous cell cancer. The impact of this polymorphic variant of CYP1B1 on cancer risk was also reflected by an association with the frequency of somatic mutations of the p53 gene. Combined genotype analysis of CYP1B1 and the glutathione transferases GSTM1 or GSTT1 has also pointed to interactive effects. Of particular interest for the industrial and environmental field is the isozyme CYP2E1. Several genotypes of this isozyme have been characterised which seem to be associated with different levels of expression of enzyme activity. The acetylator status for NAT2 can be determined by genotyping or by phenotyping. In the pathogenesis of human bladder cancer due to occupational exposure to "classical" aromatic amines (benzidine, 4-aminodiphenyl, 1-naphthylamine) acetylation by NAT2 is regarded as a detoxication step. Interestingly, the underlying European findings of a higher susceptibility of slow acetylators towards aromatic amines are in contrast to findings in Chinese workers occupationally exposed to aromatic amines which points to different mechanisms of susceptibility between European and Chinese populations. Regarding human bladder cancer, the hypothesis has been put forward that genetic polymorphism of GSTM1 might be linked with the occurrence of this tumour type. This supports the hypothesis that exposure to PAH might causally be involved in urothelial cancers. The human polymorphic GST catalysing conjugation of halomethanes, dihalomethanes, ethylene oxide and a number of other industrial compounds could be characterised as a class theta enzyme (GSTT1) by means of molecular biology. "Conjugator" and "non-conjugator" phenotypes are coincident with the presence and absence of the GSTT1 gene. There are wide variations in the frequencies of GSTT1 deletion (GSTT1*0/0) among different ethnicities. Human phenotyping is facilitated by the GST activity towards methyl bromide or ethylene oxide in erythrocytes which is representative of the metabolic GSTT1 competence of the entire organism. Inter-individual variations in xenobiotic metabolism capacities may be due to polymorphisms of the genes coding for the enzymes themselves or of the genes coding for the receptors or transcription factors which regulate the expression of the enzymes. Also, polymorphisms in several regions of genes may cause altered ligand affinity, transactivation activity or expression levels of the receptor subsequently influencing the expression of the downstream target genes. Studies of individual susceptibility to toxicants and gene-environment interaction are now emerging as an important component of molecular epidemiology.
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Affiliation(s)
- Ricarda Thier
- School of Biomedical Sciences, Department of Physiology and Pharmacology, University of Queensland, St. Lucia, Australia
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Synthesis and reactivity of a very strong reducing agent containing a quadruple bond: structures of W2(hpp)4 and W2(hpp)4Cl2·4CH2Cl2. INORG CHEM COMMUN 2003. [DOI: 10.1016/s1387-7003(02)00701-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Cotton FA, Daniels LM, Murillo CA, Timmons DJ, Wilkinson CC. The extraordinary ability of guanidinate derivatives to stabilize higher oxidation numbers in dimetal units by modification of redox potentials: structures of Mo(2)(5+) and Mo(2)(6+) compounds. J Am Chem Soc 2002; 124:9249-56. [PMID: 12149031 DOI: 10.1021/ja0266464] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Full characterization of the first homologous series of dimolybdenum paddlewheel compounds having electronic configurations of the types sigma(2)pi(4)delta(x), x = 2, 1, 0, and Mo-Mo bond orders of 4, 3.5, and 3, respectively, has been accomplished with the guanidinate-type ligand hpp (hpp = the anion of 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine). Essentially quantitative oxidation of Mo(2)(hpp)(4), 1, by CH(2)Cl(2) gives Mo(2)(hpp)(4)Cl, 2. The halide in 2 can be replaced by reaction with TlBF(4) to produce Mo(2)(hpp)(4)(BF(4)), 3. Further oxidation of 2 by AgBF(4) produces Mo(2)(hpp)(4)ClBF(4), 4. The change from bond order 4 (in 1) to 3.5 in Mo(2)(hpp)(4)Cl is accompanied by an increase in the Mo-Mo bond length of 0.061 to 2.1280(4) A. A further increase of 0.044 A in the Mo-Mo distance to 2.172(1) A is observed as the bond order decreases to 3 in 4. At the same time, the Mo-N distances decrease smoothly as the oxidation state of the Mo atoms increases. Electrochemical studies have shown two chemically reversible processes at very negative potentials, E(1)(1/2)= -0.444 V and E(2)(1/2)= -1.271 V versus Ag/AgCl. These correspond to the processes Mo(2)(6+/5+) and Mo(2)(5+/4+), respectively. The latter potential is displaced by over 1.5 V relative to those of the Mo(2)(formamidinate)(4) compounds and the first one has never been observed in such complexes. Thus, in surprising contrast to previously observed behavior of the dimolybdenum unit, when it is surrounded by the very basic guanidinate ligand hpp, there is an extraordinary stabilization of the higher oxidation numbers of the molybdenum atoms.
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Affiliation(s)
- F Albert Cotton
- Laboratory for Molecular Structure and Bonding, Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255, USA.
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Cloutier JF, Castonguay A, O'Connor TR, Drouin R. Alkylating agent and chromatin structure determine sequence context-dependent formation of alkylpurines. J Mol Biol 2001; 306:169-88. [PMID: 11237592 DOI: 10.1006/jmbi.2000.4371] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We determined the adduct maps of S(N)1 and S(N)2 alkylating agents in cultured human cells (in vivo) and in vitro to probe DNA-protein interactions along sequences of the promoter and exon 1 of the Fragile-X mental retardation 1 (FMR1) gene. Using ligation-mediated polymerase chain reaction (LMPCR), we compared the piperidine-sensitive alkylpurines sites generated by treating cultured cells (in vivo) and naked DNA (in vitro) with S(N)1 (N-methyl-N-nitrosourea, N-nitroso(acetoxymethyl)methylamine and 1-methyl-3-nitro-1-nitrosoguanidine) and S(N)2 alkylating agents (dimethyl sulfate (DMS), methane sulfonic acid methyl ester, iodo methane, diethyl sulfate, methane sulfonic acid ethyl ester and iodo ethane). The FMR1 promoter has four sites where DNA-protein interactions are observed. In these regions, the S(N)1 methylating agent reactions produced only hypo-reactive sites. In contrast, iodoalkane S(N)2 alkylating agents (MeI and EtI) reactions generated only hyper-reactive sites. Although there are hyper-reactive sites for the other S(N)2 reagents, the hyper-reactive site at +14 on the FMR1 map is more pronounced for the sulfate and sulfonate-derived alkylating agents than for the iodoalkanes. However, DMS modification in the presence of methyl sulfone, a compound that does not alkylate DNA, eliminates the hyper-reactive site observed at +14. This suggests that the electron-rich oxygen atoms of the sulfate and sulfonate-derived S(N)2 alkylating agent structure position the alkylating moiety to the neighboring N-7-guanine position to favor alkyl transfer to the guanine. Using KMnO(4) to probe for single-strand DNA, an unpaired cytosine base was detected at the 5'-side of the hyper- reactive guanine base at position +14, consistent with the formation of a local DNA single-strand bulge. In conclusion, we show that the sequence context-dependent formation of alkylpurines is determined by the chemical nature of the alkylating agent, the DNA sequence context, chromatin structure, and the presence of other non-reactive molecules that can inhibit alkylation.
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Affiliation(s)
- J F Cloutier
- Laboratory of Cancer Etiology and Chemoprevention, Faculty of Pharmacy, Laval University, Quebec City, G1K 7P4, Canada
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Abstract
The Purkinje cells and the granule cells are the most important targets in cerebellum for toxic substances. The Purkinje cells are among the largest neuron in the brain and are very sensitive to ischaemia, bilirubin, ethanol and diphenylhydantoin. The granule cells are small and seem to be sensitive to loss of intracellular glutathione. Granule cells are sensitive to methyl halides, thiophene, methyl mercury, 2-chloropropionic acid and trichlorfon. The Purkinje cells appear in the rat brain on pre-natal day 14-16, whereas the granule cells appear post-natally. Both cells are sensitive to excitotoxic chemicals and also to an effect on DNA or its repair mechanisms.
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Affiliation(s)
- F Fonnum
- Norwegian Defence Research Establishment, Division for Protection and Material, 2027, Kjeller, Norway.
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Chamberlain MP, Sturgess NC, Lock EA, Reed CJ. Methyl iodide toxicity in rat cerebellar granule cells in vitro: the role of glutathione. Toxicology 1999; 139:27-37. [PMID: 10614686 DOI: 10.1016/s0300-483x(99)00099-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The monohalomethane methyl iodide (MeI) is toxic to a number of organ systems including the central nervous system. Clinical symptoms of neurotoxicity suggest that the cerebellum is the target within the brain, and we have now modelled the toxicity of MeI in cultured rat cerebellar granule cells. Cytotoxicity is maximal 24 h after a 5 min exposure to MeI, and the EC50 for MeI under these conditions was calculated to be 1.6 mM. The glutathione S-transferase (GST) dependent metabolism of MeI was investigated in these cultures. There was a marked decrease in intracellular glutathione (GSH) 15 min after exposure to MeI, and GSH concentrations then increased, reaching 130% of control levels 7 h after exposure. To investigate the role of conjugation with GSH in the toxicity of MeI, GSH levels were modulated prior to exposure. Depletion of GSH exacerbated the cytotoxicity of MeI while provision of a bioavailable source of GSH was protective. Inclusion of antioxidants [vitamin E, butylated hydroxytoluene (BHT) or desferrioxamine mesylate (DF)] also protected against the cytotoxicity of MeI. Our in vitro data suggest that MeI is conjugated with GSH in the cerebellum, and the resulting extensive depletion of GSH may be the first step en route to toxicity, rendering the tissue susceptible to methylation and/or oxidative stress.
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Affiliation(s)
- M P Chamberlain
- School of Biomolecular Sciences, Liverpool John Moores University, UK
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Goergens HW. Specific factors leading to interindividual variability in response to occupational toxicants. ARCHIVES OF TOXICOLOGY. SUPPLEMENT. = ARCHIV FUR TOXIKOLOGIE. SUPPLEMENT 1996; 18:357-61. [PMID: 8678812 DOI: 10.1007/978-3-642-61105-6_33] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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Bolt HM. Genetic predisposition in occupational toxicology. ARCHIVES OF TOXICOLOGY. SUPPLEMENT. = ARCHIV FUR TOXIKOLOGIE. SUPPLEMENT 1996; 18:362-6. [PMID: 8678813 DOI: 10.1007/978-3-642-61105-6_34] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- H M Bolt
- Institut Für Arbeitsphysiologie, Universität Dortmund, Germany
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Bolt HM. Human GSH-transferase in risk assessment. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1996; 387:405-9. [PMID: 8794235 DOI: 10.1007/978-1-4757-9480-9_49] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- H M Bolt
- Institut für Arbeitsphysiologie an der Universität Dortmund, Germany
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Abstract
The monohalomethanes (methyl iodide, methyl bromide and methyl chloride) are widely used industrial methylating agents with pronounced acute and chronic toxicity in both experimental animals and man. Recently inhalation exposure of rats to methyl bromide has been shown to result in severe olfactory toxicity. This study examined the effects on the rat nasal cavity of inhalation of methyl iodide (100 ppm for 0.5-6 h), and demonstrated that methyl iodide is a more potent olfactory toxin than methyl bromide. Within the nasal cavity the olfactory epithelium was the principle target tissue, and it was only at high doses (600 ppm.h) that limited damage to transitional epithelium occurred. The squamous and respiratory epithelia were consistently unaffected. Within olfactory epithelium the sustentacular cells were the primary cellular target and damage to sensory cells appeared to be a secondary event. Methyl iodide induced olfactory damage was reversible, and 2 weeks after exposure almost complete repair had taken place.
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Affiliation(s)
- C J Reed
- School of Biomolecular Sciences, Liverpool John Moores University, UK
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Ploemen JH, Wormhoudt LW, van Ommen B, Commandeur JN, Vermeulen NP, van Bladeren PJ. Polymorphism in the glutathione conjugation activity of human erythrocytes towards ethylene dibromide and 1,2-epoxy-3-(p-nitrophenoxy)-propane. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1243:469-76. [PMID: 7727522 DOI: 10.1016/0304-4165(94)00175-w] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
In this study a polymorphism in the conjugating activity of human erythrocyte cytosol towards the dihaloethane, ethylene dibromide (EDB; 1,2-dibromoethane) was found. Two out of 12 human erythrocyte cytosols did not catalyze the formation of glutathione (GSH) conjugates of [1,2-14C]EDB. Ten cytosols formed the S,S'-ethylenebis(GSH) conjugate at a rate ranging from 0.5 to 3.2 (mean 1.76 +/- 0.95) pmol min-1 (mg protein)-1. The activity of the cytosols towards EDB was compared with the activity towards 1,2-epoxy-3-(p-nitrophenoxy)-propane (EPNP) and 1-chloro-2,4-dinitrobenzene (CDNB). The GSH conjugates formed from EDB, EPNP and CDNB were all quantified by HPLC. Every cytosol was active with the classical GST substrate CDNB (2.04 +/- 0.74 nmol min-1 (mg protein)-1). The two samples not showing any detectable activity towards EDB were also inactive towards EPNP: The activity towards EDB correlated significantly with EPNP (rs = 0.90, P < 0.005; Spearman's rank correlation), but not with CDNB (rs = 0.36, P > 0.10). In the incubations with EPNP, the alpha-, mu-, and pi- class glutathione S-transferase (GST) inhibitor S-hexyl(GSH) was included, indicating that the class-theta GST is the principal GST class conjugating EDB in erythrocyte cytosol. The apparent polymorphism of GST-theta which has recently been recognized to be crucial for several mono- and dihalomethanes, will thus also have considerable implications for the risk assessment of EDB.
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Affiliation(s)
- J H Ploemen
- TNO Nutrition and Food Research Institute, Division of Toxicology, Zeist, The Netherlands
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Determination of methylated globin and albumin for biomonitoring of exposure to methylating agents using HPLC with precolumn fluorescent derivatization. ACTA ACUST UNITED AC 1994. [DOI: 10.1007/bf00323669] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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