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Yasui M, Fukuda T, Ukai A, Maniwa J, Imamura T, Hashizume T, Yamamoto H, Shibuya K, Narumi K, Fujiishi Y, Okada E, Fujishima S, Yamamoto M, Otani N, Nakamura M, Nishimura R, Ueda M, Mishima M, Matsuzaki K, Takeiri A, Tanaka K, Okada Y, Nakagawa M, Hamada S, Kajikawa A, Honda H, Adachi J, Misaki K, Ogawa K, Honma M. Weight of evidence approach using a TK gene mutation assay with human TK6 cells for follow-up of positive results in Ames tests: a collaborative study by MMS/JEMS. Genes Environ 2021; 43:7. [PMID: 33676587 PMCID: PMC7937321 DOI: 10.1186/s41021-021-00179-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 02/16/2021] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Conflicting results between bacterial mutagenicity tests (the Ames test) and mammalian carcinogenicity tests might be due to species differences in metabolism, genome structure, and DNA repair systems. Mutagenicity assays using human cells are thought to be an advantage as follow-up studies for positive results in Ames tests. In this collaborative study, a thymidine kinase gene mutation study (TK6 assay) using human lymphoblastoid TK6 cells, established in OECD TG490, was used to examine 10 chemicals that have conflicting results in mutagenicity studies (a positive Ames test and a negative result in rodent carcinogenicity studies). RESULTS Two of 10 test substances were negative in the overall judgment (20% effective as a follow-up test). Three of these eight positive substances were negative after the short-term treatment and positive after the 24 h treatment, despite identical treatment conditions without S9. A toxicoproteomic analysis of TK6 cells treated with 4-nitroanthranilic acid was thus used to aid the interpretation of the test results. This analysis using differentially expressed proteins after the 24 h treatment indicated that in vitro specific oxidative stress is involved in false positive response in the TK6 assay. CONCLUSIONS The usefulness of the TK6 assay, by current methods that have not been combined with new technologies such as proteomics, was found to be limited as a follow-up test, although it still may help to reduce some false positive results (20%) in Ames tests. Thus, the combination analysis with toxicoproteomics may be useful for interpreting false positive results raised by 24 h specific reactions in the assay, resulting in the more reduction (> 20%) of false positives in Ames test.
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Affiliation(s)
- Manabu Yasui
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, 3-25-26 Tono-machi, Kawasaki-ku, Kawasaki, Kanagawa 210-9501 Japan
| | - Takayuki Fukuda
- Tokyo Laboratory, BoZo Research Center Inc., 1-3-11, Hanegi, Setagaya-ku, Tokyo 156-0042 Japan
| | - Akiko Ukai
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, 3-25-26 Tono-machi, Kawasaki-ku, Kawasaki, Kanagawa 210-9501 Japan
| | - Jiro Maniwa
- AstraZeneca KK, 3-1 Ofuka-cho, Kita-ku, Osaka, 530-0011 Japan
| | - Tadashi Imamura
- Ina Research Inc., 2148-188 Nishiminowa, Ina-shi, Nagano 399-4501 Japan
| | - Tsuneo Hashizume
- Scientific Product Assessment Center, R&D Group, Japan Tobacco Inc., 6-2, Umegaoka, Aoba-ku, Yokohama, Kanagawa 227-8512 Japan
| | - Haruna Yamamoto
- Scientific Product Assessment Center, R&D Group, Japan Tobacco Inc., 6-2, Umegaoka, Aoba-ku, Yokohama, Kanagawa 227-8512 Japan
| | - Kaori Shibuya
- Scientific Product Assessment Center, R&D Group, Japan Tobacco Inc., 6-2, Umegaoka, Aoba-ku, Yokohama, Kanagawa 227-8512 Japan
| | - Kazunori Narumi
- Yakult Central Institute, 5-11 Izumi, Kunitachi-shi, Tokyo 186-8650 Japan
| | - Yohei Fujiishi
- Yakult Central Institute, 5-11 Izumi, Kunitachi-shi, Tokyo 186-8650 Japan
| | - Emiko Okada
- Yakult Central Institute, 5-11 Izumi, Kunitachi-shi, Tokyo 186-8650 Japan
| | - Saori Fujishima
- Chemicals Evaluation and Research Institute, Japan, 3-822, Ishii-machi, Hita-shi, Oita 877-0061 Japan
| | - Mika Yamamoto
- Astellas Pharma Inc., 21, Miyukigaoka, Tsukuba-shi, Ibaraki 305-8585 Japan
| | - Naoko Otani
- Astellas Pharma Inc., 21, Miyukigaoka, Tsukuba-shi, Ibaraki 305-8585 Japan
| | - Maki Nakamura
- Tokyo Laboratory, BoZo Research Center Inc., 1-3-11, Hanegi, Setagaya-ku, Tokyo 156-0042 Japan
| | - Ryoichi Nishimura
- Tokyo Laboratory, BoZo Research Center Inc., 1-3-11, Hanegi, Setagaya-ku, Tokyo 156-0042 Japan
| | - Maya Ueda
- Genotoxicology Laboratory, BioSafety Research Center Inc., 582-2 Shioshinden, Iwata-shi, Shizuoka 437-1213 Japan
| | - Masayuki Mishima
- Chugai Pharmaceutical Co., Ltd, 1-135, Komakado, Gotemba, Shizuoka 412-8513 Japan
| | - Kaori Matsuzaki
- Chugai Pharmaceutical Co., Ltd, 1-135, Komakado, Gotemba, Shizuoka 412-8513 Japan
| | - Akira Takeiri
- Chugai Pharmaceutical Co., Ltd, 1-135, Komakado, Gotemba, Shizuoka 412-8513 Japan
| | - Kenji Tanaka
- Chugai Pharmaceutical Co., Ltd, 1-135, Komakado, Gotemba, Shizuoka 412-8513 Japan
| | - Yuki Okada
- Toxicology Research Department, Teijin Institute for Bio-medical Research, Teijin Pharma Limited, 4-3-2, Asahigaoka, Hino, Tokyo 191-8512 Japan
| | - Munehiro Nakagawa
- Nonclinical Research Center, LSI Medience Corporation, 14-1, Sunayama, Kamisu-shi, Ibaraki 314-0255 Japan
| | - Shuichi Hamada
- Tokyo Laboratory, BoZo Research Center Inc., 1-3-11, Hanegi, Setagaya-ku, Tokyo 156-0042 Japan
| | - Akihiko Kajikawa
- Nonclinical Research Center, LSI Medience Corporation, 14-1, Sunayama, Kamisu-shi, Ibaraki 314-0255 Japan
| | - Hiroshi Honda
- R&D Safety Science Research, Kao Corporation, Haga–Gun, Tochigi Japan
| | - Jun Adachi
- Laboratory of Proteomics for Drug Discovery, Center for Drug Design Research, National Institutes of Biomedical Innovation, Health and Nutrition, 7-6-8 Saito-Asagi, Ibarak, Osaka 567-0085 Japan
| | - Kentaro Misaki
- School of Nursing, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526 Japan
| | - Kumiko Ogawa
- Division of Pathology, National Institute of Health Sciences, 3-25-26 Tono-machi, Kawasaki-ku, Kawasaki, Kanagawa 210-9501 Japan
| | - Masamitsu Honma
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, 3-25-26 Tono-machi, Kawasaki-ku, Kawasaki, Kanagawa 210-9501 Japan
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Younes M, Aquilina G, Castle L, Engel KH, Fowler P, Fürst P, Gürtler R, Gundert-Remy U, Husøy T, Mennes W, Moldeus P, Oskarsson A, Shah R, Waalkens-Berendsen I, Wölfle D, Boon P, Crebelli R, Di Domenico A, Filipič M, Mortensen A, Van Loveren H, Woutersen R, Giarola A, Lodi F, Riolo F, Frutos Fernandez MJ. Re-evaluation of hydrochloric acid (E 507), potassium chloride (E 508), calcium chloride (E 509) and magnesium chloride (E 511) as food additives. EFSA J 2019; 17:e05751. [PMID: 32626371 PMCID: PMC7009240 DOI: 10.2903/j.efsa.2019.5751] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The Panel on Food Additives and Flavourings added to Food (FAF) provided a scientific opinion re-evaluating the safety of chlorides (E 507-509, E 511) as food additives. Chlorides are authorised food additives in the EU in accordance with Annex II and III to Regulation (EC) No 1333/2008. In the non- brand-loyal scenario, mean exposure to chlorides (E 507-509, E 511) as food additives ranged from 2 mg/kg body weight (bw) per day in the elderly to 42 mg/kg bw per day in toddlers. The 95th percentile of exposure ranged from 5 mg/kg bw per day in the elderly to 71 mg/kg bw per day in toddlers. Chloride is an essential nutrient and after absorption is distributed to organs and tissues. The Panel considered chlorides to be of low acute oral toxicity and there is no concern with respect to genotoxicity and carcinogenicity. No effects were reported in developmental toxicity studies in rats following administration of magnesium chloride hexahydrate at 800 mg/kg bw per day. Some animal studies suggested a role of chloride in increasing blood pressure but based on the toxicological database available the Panel considered human data more appropriate to identify a level of chloride intake which does not raise a safety concern. The Panel identified a human dose of 40 mg chloride/kg bw per day as a reference value for the assessment. Mean levels of exposure in all age groups were below or at this reference value, which indicates no safety concern. In some age groups (toddlers, children and adolescents), the 95th percentile exposure estimates were slightly above this reference value. The Panel concluded that the exposure to chloride from hydrochloric acid and its potassium, calcium and magnesium salts (E 507, E 508, E 509 and E 511) does not raise a safety concern at the reported use and use levels.
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Fiume MM, Bergfeld WF, Belsito DV, Hill RA, Klaassen CD, Liebler DC, Marks JG, Shank RC, Slaga TJ, Snyder PW, Gill LJ, Heldreth B. Safety Assessment of Monosaccharides, Disaccharides, and Related Ingredients as Used in Cosmetics. Int J Toxicol 2019; 38:5S-38S. [PMID: 31170840 DOI: 10.1177/1091581818814189] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The Cosmetic Ingredient Review Expert Panel (Panel) assessed the safety of 25 monosaccharides, disaccharides, and related ingredients and concluded these are safe in the present practices of use and concentration described in the safety assessment. Many of these ingredients are common dietary sugars, dietary sugar replacements, or very closely related analogs and salts; 7 of the ingredients are listed by the Food and Drug Administration as generally recognized as safe food substances. The most commonly reported cosmetic function is as a skin-conditioning agent; other commonly reported functions are use as a humectant or as a flavoring agent. The Panel reviewed the animal and clinical data included in this assessment, acknowledged that the oral safety of many of these ingredients has been well established, and found it appropriate to extrapolate the existing information to conclude on the safety of all the monosaccharides, disaccharides, and related ingredients.
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Affiliation(s)
- Monice M Fiume
- 1 Cosmetic Ingredient Review Senior Director, Washington, DC, USA
| | - Wilma F Bergfeld
- 2 Cosmetic Ingredient Review Expert Panel Member, Washington, DC, USA
| | - Donald V Belsito
- 2 Cosmetic Ingredient Review Expert Panel Member, Washington, DC, USA
| | - Ronald A Hill
- 2 Cosmetic Ingredient Review Expert Panel Member, Washington, DC, USA
| | - Curtis D Klaassen
- 2 Cosmetic Ingredient Review Expert Panel Member, Washington, DC, USA
| | - Daniel C Liebler
- 2 Cosmetic Ingredient Review Expert Panel Member, Washington, DC, USA
| | - James G Marks
- 2 Cosmetic Ingredient Review Expert Panel Member, Washington, DC, USA
| | - Ronald C Shank
- 2 Cosmetic Ingredient Review Expert Panel Member, Washington, DC, USA
| | - Thomas J Slaga
- 2 Cosmetic Ingredient Review Expert Panel Member, Washington, DC, USA
| | - Paul W Snyder
- 2 Cosmetic Ingredient Review Expert Panel Member, Washington, DC, USA
| | - Lillian J Gill
- 3 Cosmetic Ingredient Review Former Director, Washington, DC, USA
| | - Bart Heldreth
- 4 Cosmetic Ingredient Review Executive Director, Washington, DC, USA
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Schisler MR, Gollapudi BB, Moore MM. Evaluation of U. S. National Toxicology Program (NTP) mouse lymphoma assay data using International Workshop on Genotoxicity Tests (IWGT) and the Organization for Economic Co-Operation and Development (OECD) criteria. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2018; 59:829-841. [PMID: 30357906 DOI: 10.1002/em.22250] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 08/21/2018] [Accepted: 08/23/2018] [Indexed: 06/08/2023]
Abstract
The forward gene mutation mouse lymphoma assay (MLA) is widely used, as part of a regulatory test battery, to identify the genotoxic potential of chemicals. It identifies mutagens capable of inducing a variety of genetic events. During the 1980s and early 1990s, the U.S. National Toxicology Program (NTP) developed a publicly available database (https://tools.niehs.nih.gov/cebs3/ui/) of MLA results. This database is used to define the mutagenic potential of chemicals, to develop structure-activity relationships (SAR), and to draw correlations to animal carcinogenicity findings. New criteria for MLA conduct and data interpretation were subsequently developed by the International Workshop for Genotoxicity Testing (IWGT) and the Organization of Economic Cooperation and Development (OECD). These recommendations are included in a new OECD Test Guideline (TG490). It is essential that early experimental data be re-examined and classified according to the current criteria to build a curated database to better inform chemical-specific evaluations and SAR models. We re-evaluated more than 1900 experiments representing 342 chemicals against the newly defined acceptance criteria for background mutant frequency (MF), cloning efficiency (CE), positive control values (modified for this evaluation due to lack of colony sizing), appropriate dose selection, and data consistency. Only 17% of the evaluated experiments met all acceptance criteria used in this re-evaluation. Results from 211 chemicals were determined to be uninterpretable, 92 were positive, and 39 equivocal. The authors could not classify any responses as negative because colony sizing was not performed for any of these experiments and it is clear, based on many experiment with unacceptably low background and positive control MFs, that mutant colony recovery was often suboptimal. This re-evaluation provides a curated database for the MLA. A similar curation should be done for other widely used genetic toxicology assays, but will be more difficult for certain assays (e.g., in vitro chromosomal aberrations) because important parameters such as level of cytotoxicity were often not evaluated/reported. Environ. Mol. Mutagen. 59:829-841, 2018. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
| | - B B Gollapudi
- Exponent, Inc., Center for Health Sciences, Alexandria, Virginia
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Abstract
Progesterone is a steroid hormone that is essential for the regulation of reproductive function. Progesterone has been approved for several indications including the treatment of anovulatory menstrual cycles, assisted reproductive technology, contraception during lactation and, when combined with estrogen, for the prevention of endometrial hyperplasia in postmenopausal hormonal therapy. In addition to its role in reproduction, progesterone regulates a number of biologically distinct processes in other tissues, particularly in the nervous system. This physiological hormone is poorly absorbed when administered in a crystalline form and is not active when given orally, unless in micronized form, or from different non-oral delivery systems that allow a more constant delivery rate. A limited number of preclinical studies have been conducted to document the toxicity, carcinogenicity and overall animal safety of progesterone delivered from different formulations, and these rather old studies showed no safety concern. More recently, it has been shown in animal experiments that progesterone, its metabolite allopregnanolone and structurally related progestins have positive effects on neuroregeneration and repair of brain damage, as well as myelin repair. These recent preclinical findings have the potential to accelerate therapeutic translation for multiple unmet neurological needs.
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Affiliation(s)
- R Sitruk-Ware
- a Center for Biomedical Research , Population Council , New York , NY , USA
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6
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Reflections on a career and on the history of genetic toxicity testing in the National Toxicology Program. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2017; 773:282-292. [DOI: 10.1016/j.mrrev.2017.03.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 02/09/2017] [Indexed: 11/20/2022]
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7
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Kirkland D, Kasper P, Martus HJ, Müller L, van Benthem J, Madia F, Corvi R. Updated recommended lists of genotoxic and non-genotoxic chemicals for assessment of the performance of new or improved genotoxicity tests. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2016; 795:7-30. [DOI: 10.1016/j.mrgentox.2015.10.006] [Citation(s) in RCA: 119] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 10/27/2015] [Accepted: 10/28/2015] [Indexed: 01/09/2023]
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9
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Cheng TF, Patton GW, Muldoon-Jacobs K. Can the L5178Y Tk+/- mouse lymphoma assay detect epigenetic silencing? Food Chem Toxicol 2013; 59:187-90. [PMID: 23778052 DOI: 10.1016/j.fct.2013.06.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 05/17/2013] [Accepted: 06/05/2013] [Indexed: 12/14/2022]
Abstract
The mouse lymphoma L5178Y Tk(+/-) assay is broadly used in toxicology to assess genotoxicity because of its known sensitivity to genotoxicants that act through a variety of mechanisms, which may include epigenetic DNA methylation. This brief article highlights the studies that have contributed to this conjecture and suggests an addition to the experimental design that could identify if the test substance is a potential epimutagen acting via hypermethylation.
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Affiliation(s)
- Tsu-Fan Cheng
- US Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Food Additive Safety, Division of Food Contact Notification, College Park, MD 20740, USA
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10
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Krishnamurthi K, Devi SS, Chakrabarti T. The Genotoxicity of Priority Polycyclic Aromatic Hydrocarbons (PAHs) Containing Sludge Samples. Toxicol Mech Methods 2012; 17:1-12. [PMID: 20020982 DOI: 10.1080/15376510600943676] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
ABSTRACT In this research work we developed in vitro tests utilizing mammalian cell cultures, which can rapidly assess effect of exposure of oily sludge-derived chemicals on human and ecological health. Many of these are hazardous to health and environment due to their toxicity and/or accumulation potential in sediments as well as in organisms. Petroleum refinery and petrochemical industry-derived oily sludges contain toxic polycyclic aromatic hydrocarbons (PAHs), some of which are lipophilic in nature. Risk assessment of environmental samples suffers from inadequate availability of toxicity data, lack of knowledge about behavior of genotoxic substances in complex matrices, paucity of information on synergistic and antagonistic interactions of mixture of components, etc.; the literature describing the behavior of genotoxic substances in complex mixtures is sparse and sometimes contradictory. The present study aims at assessing the genotoxic potential of oily sludges collected from an integrated petroleum refinery and petrochemical industry located in the southwestern part of India and a petrochemical industry located in the western part of India using a battery of genotoxicity assays such as DNA damage/strand break, chromosomal aberration, p(53) protein induction, and apoptosis in CHO-K1 cell culture system. Exposure with different dose levels of sludge extracts (25, 50, 100 muL) in CHO-K1 cells could cause statistically significant level of (P < 0.001) DNA damage, chromosomal aberration, p(53) protein induction, and apoptosis in comparison to negative control treatment groups, and the genotoxicity was attributed to PAHs present in the sludge as identified by GC-MS. This implies that the sludges are genotoxic in nature in mammalian cells tested, and the exposure to these may pose a potential genotoxic risk to human beings.
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Affiliation(s)
- K Krishnamurthi
- Environmental Biotechnology Division, National Environmental Engineering Research Institute, Nehru Marg, Nagpur, India
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Greywe D, Kreutz J, Banduhn N, Krauledat M, Scheel J, Schroeder KR, Wolf T, Reisinger K. Applicability and robustness of the hen's egg test for analysis of micronucleus induction (HET-MN): Results from an inter-laboratory trial. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2012; 747:118-134. [DOI: 10.1016/j.mrgentox.2012.04.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 02/13/2012] [Accepted: 04/24/2012] [Indexed: 11/30/2022]
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Abstract
The mouse lymphoma TK assay (MLA) is part of an in vitro battery of tests designed to predict risk assessment prior to in vivo testing. The test has the potential to detect mutagenic and clastogenic events at the thymidine kinase (tk) locus of L5178Y mouse lymphoma tk ( +/- ) cells by measuring resistance to the lethal nucleoside analogue triflurothymidine (TFT). Cells may be plated for viability and mutation in semi-solid agar (agar assay) or in 96-well microtitre plates (microwell assay). When added to selective medium containing TFT, wild-type tk ( +/- ) cells die, but TFT cannot be incorporated into the DNA of mutant tk ( -/- ) cells, which survive to form colonies that may be large (indicative of gene mutation) or small (indicative of chromosomal mutation) in nature. Mutant frequency is expressed as the number of mutants per 10(6) viable cells.
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Smart DJ, Ahmedi KP, Harvey JS, Lynch AM. Genotoxicity screening via the γH2AX by flow assay. Mutat Res 2011; 715:25-31. [PMID: 21824484 DOI: 10.1016/j.mrfmmm.2011.07.001] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Revised: 06/10/2011] [Accepted: 07/08/2011] [Indexed: 05/31/2023]
Abstract
The measurement of serine139-phosphorylated histone H2AX (γH2AX) provides a biomarker of DNA double-strand breaks (DSBs) and may identify potential genotoxic activity. In order to evaluate a flow cytometry assay for γH2AX detection (hereafter termed the γH2AX by flow assay), 6 prototypical (3 pro- and 3 proximate) genotoxins, i.e. dimethylbenz[a]anthracene (DMBA), 2-acetylaminofluorene (2-AAF), benzo[a]pyrene (B[a]P), methyl methane sulphonate (MMS), methyl nitrosourea (MNU) and 4-nitroquinoline oxide (4NQO), were selected to define assay evaluation criteria. In addition, 3 non-genotoxic cytotoxins (phthalic anhydride, n-butyl chloride and hexachloroethane) were included to investigate the influence of cytotoxicity on assay performance. At similar cytotoxicity levels (relative cell counts; RCC 75-40%) all prototypical genotoxins induced marked concentration-dependent increases in γH2AX compared with the non-genotoxins. As a result, assay evaluation criteria for a positive effect were defined as >1.5-fold γH2AX @ RCC >25%. Twenty five additional chemicals with diverse structures and genotoxic activity were selected to evaluate the γH2AX by flow assay. Results were compared with Ames bacterial and in vitro mammalian genotoxicity tests (mouse lymphoma assay and/or chromosome aberration assay). γH2AX by flow assay results were highly predictive of Ames (sensitivity 100%; specificity 67%; concordance 82%) and in vitro mammalian genotoxicity tests (sensitivity 91%; specificity 89%; concordance 91%) and provide additional evidence that γH2AX is a biomarker of potential genotoxic activity, underpinned mechanistically by the cellular response to DSBs. Discordant findings were predominately attributed to differences in specificity for some mammalian cell genotoxins that are Ames non-mutagens or for "biologically-irrelevant" positives in the mammalian tests. Simple anilines were classified as genotoxic following rat liver S9-mediated bioactivation, however, effects on γH2AX were atypical and limited to a small sub-population of S-phase nuclei. Nevertheless, the γH2AX by flow assay represents a novel genotoxicity assay with the potential to flag both pro- and proximate genotoxins.
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Affiliation(s)
- D J Smart
- Safety Assessment, GlaxoSmithKline R&D, Park Road, Ware, Hertfordshire SG12 0DP, UK.
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Kirkland D, Reeve L, Gatehouse D, Vanparys P. A core in vitro genotoxicity battery comprising the Ames test plus the in vitro micronucleus test is sufficient to detect rodent carcinogens and in vivo genotoxins. Mutat Res 2011; 721:27-73. [PMID: 21238603 DOI: 10.1016/j.mrgentox.2010.12.015] [Citation(s) in RCA: 161] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Revised: 11/12/2010] [Accepted: 12/15/2010] [Indexed: 01/27/2023]
Abstract
In vitro genotoxicity testing needs to include tests in both bacterial and mammalian cells, and be able to detect gene mutations, chromosomal damage and aneuploidy. This may be achieved by a combination of the Ames test (detects gene mutations) and the in vitro micronucleus test (MNvit), since the latter detects both chromosomal aberrations and aneuploidy. In this paper we therefore present an analysis of an existing database of rodent carcinogens and a new database of in vivo genotoxins in terms of the in vitro genotoxicity tests needed to detect their in vivo activity. Published in vitro data from at least one test system (most were from the Ames test) were available for 557 carcinogens and 405 in vivo genotoxins. Because there are fewer publications on the MNvit than for other mammalian cell tests, and because the concordance between the MNvit and the in vitro chromosomal aberration (CAvit) test is so high for clastogenic activity, positive results in the CAvit test were taken as indicative of a positive result in the MNvit where there were no, or only inadequate data for the latter. Also, because Hprt and Tk loci both detect gene-mutation activity, a positive Hprt test was taken as indicative of a mouse-lymphoma Tk assay (MLA)-positive, where there were no data for the latter. Almost all of the 962 rodent carcinogens and in vivo genotoxins were detected by an in vitro battery comprising Ames+MNvit. An additional 11 carcinogens and six in vivo genotoxins would apparently be detected by the MLA, but many of these had not been tested in the MNvit or CAvit tests. Only four chemicals emerge as potentially being more readily detected in MLA than in Ames+MNvit--benzyl acetate, toluene, morphine and thiabendazole--and none of these are convincing cases to argue for the inclusion of the MLA in addition to Ames+MNvit. Thus, there is no convincing evidence that any genotoxic rodent carcinogens or in vivo genotoxins would remain undetected in an in vitro test battery consisting of Ames+MNvit.
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Affiliation(s)
- David Kirkland
- Kirkland Consulting, PO Box 79, Tadcaster LS24 0AS, United Kingdom.
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Bomhard EM, Herbold BA. Genotoxic Activities of Aniline and its Metabolites and Their Relationship to the Carcinogenicity of Aniline in the Spleen of Rats. Crit Rev Toxicol 2008; 35:783-835. [PMID: 16468500 DOI: 10.1080/10408440500442384] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Aniline (in the form of its hydrochloride) has been shown to induce a rather rare spectrum of tumors in the spleen of Fischer 344 rats. The dose levels necessary for this carcinogenic activity were in a range where also massive effects on the blood and non-neoplastic splenotoxicity as a consequence of methemoglobinemia were to be observed. This review aimed at clarifying if aniline itself or one of its metabolites has a genotoxic potential which would explain the occurrence of the spleen tumors in rats as a result of a primary genetic activity. The database for aniline and its metabolites is extremely heterogeneous. With validated assays it ranges from a few limited Ames tests (o- and m-hydroxyacetanilide, phenylhydroxylamine, nitrosobenzene) to a broad range of studies covering all genetic endpoints partly with several studies of the same or different test systems (aniline, p-aminophenol, p-hydroxyacetanilide). This makes a direct comparison rather difficult. In addition, a varying number of results with as yet not validated systems are available for aniline and its metabolites. Most results, especially those with validated and well performed/documented studies, did not indicate a potential of aniline to induce gene mutations. In five different mouse lymphoma tests, where colony sizing was performed only in one test, aniline was positive. If this indicates a peculiar feature of a point mutagenic potential or does represent a part of the clastogenic activity for which there is evidence in vitro as well as in vivo remains to be investigated. There is little evidence for a DNA damaging potential of aniline. The clastogenic activity in vivo is confined to dose levels, which are close to lethality essentially due to hematotoxic effects. The quantitatively most important metabolites for experimental animals as well as for humans (p-aminophenol, p-hydroxyacetanilide) seem to have a potential for inducing chromosomal damage in vitro and, at relatively high dose levels, also in vivo. This could be the explanation for the clastogenic effects that have been observed after high doses/concentrations with aniline. They do not induce gene mutations and there is little evidence for a DNA damaging potential. None of these metabolites revealed a splenotoxic potential comparable to that of aniline in studies with repeated or long-term administration to rats. The genotoxicity database on those metabolites with a demonstrated and marked splenotoxic potential, i.e. phenylhydroxylamine, nitrosobenzene, is unfortunately very limited and does not allow to exclude with certainty primary genotoxic events in the development of spleen tumors. But quite a number of considerations by analogy from other investigations support the conclusion that the effects in the spleen do not develop on a primary genotoxic basis. The weight of evidences suggests that the carcinogenic effects in the spleen of rats are the endstage of a chronic high-dose damage of the blood leading to a massive overload of the spleen with iron, which causes chronic oxidative stress. This conclusion, based essentially on pathomorphological observations, and analogy considerations thereof by previous authors, is herewith reconfirmed under consideration of the more recently reported studies on the genotoxicity of aniline and its metabolites, on biochemical measurements indicating oxidative stress, and on the metabolism of aniline. It is concluded that there is no relationship between the damage to the chromosomes at high, toxic doses of aniline and its major metabolites p-aminophenol/p-hydroxyacetanilide and the aniline-induced spleen tumors in the rat.
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Affiliation(s)
- Ernst M Bomhard
- Institute of Toxicology, Bayer Healthcare AG, D-42096 Wuppertal, Germany.
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Kayani M, Parry JM. The detection and assessment of the aneugenic potential of selected oestrogens, progestins and androgens using the in vitro cytokinesis blocked micronucleus assay. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2008; 651:40-5. [DOI: 10.1016/j.mrgentox.2007.10.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2007] [Accepted: 10/28/2007] [Indexed: 10/22/2022]
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Hsu CH, Stedeford T, Okochi-Takada E, Ushijima T, Noguchi H, Muro-Cacho C, Holder JW, Banasik M. Framework analysis for the carcinogenic mode of action of nitrobenzene. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART C, ENVIRONMENTAL CARCINOGENESIS & ECOTOXICOLOGY REVIEWS 2007; 25:155-84. [PMID: 17558784 DOI: 10.1080/10590500701399234] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Nitrobenzene (CASRN: 98-95-3) has been shown to induce cancers in many tissues including kidney, liver, and thyroid, following chronic inhalation in animals. However, with a few exceptions, genotoxicity assays using nitrobenzene have given negative results. Some DNA binding/adduct studies have brought forth questionable results and, considering the available weight of evidence, it does not appear that nitrobenzene causes cancer via a genotoxic mode of action. Nitrobenzene produces a number of free radicals during its reductive metabolism, in the gut as well as at the cellular level, and generates superoxide anion as a by-product during oxidative melabolism. The reactive species generated during nitrobenzene metabolism are considered candidates for carcinogenicity. Furthermore, several lines of evidence suggest that nitrobenzene exerts its carcinogenicity through a non-DNA reactive (epigenetic) fashion, such as a strong temporal relationship between non-, pre-, and neoplastic lesions leading to carcinogenesis. In this report, we first describe the absorption, distribution, metabolism, and excretion of nitrobenzene followed by a summary of the available genotoxicity studies and the only available cancer bioassay. We subsequently refer to the mode of action framework of the U.S. Environmental Protection Agency's 2005 Guidelines for Carcinogen Risk Assessment as a basis for presenting possible modes of action for nitrobenzene-induced cancers of the liver, thyroid, and kidney, as supported by the available experimental data. The rationale(s) regarding human relevance of each mode of action is also presented. Finally, we hypothesize that the carcinogenic mode of action for nitrobenzene is multifactorial in nature and reflective of free radicals, inflammation, and/or altered methylation.
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Affiliation(s)
- Ching-Hung Hsu
- National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency. Washington, DC, USA.
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Kirkland DJ, Henderson L, Marzin D, Müller L, Parry JM, Speit G, Tweats DJ, Williams GM. Testing strategies in mutagenicity and genetic toxicology: An appraisal of the guidelines of the European Scientific Committee for Cosmetics and Non-Food Products for the evaluation of hair dyes. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2005; 588:88-105. [PMID: 16326131 DOI: 10.1016/j.mrgentox.2005.09.006] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2005] [Revised: 08/12/2005] [Accepted: 09/09/2005] [Indexed: 11/23/2022]
Abstract
The European Scientific Committee on Cosmetics and Non-Food Products (SCCNFP) guideline for testing of hair dyes for genotoxic/mutagenic/carcinogenic potential has been reviewed. The battery of six in vitro tests recommended therein differs substantially from the batteries of two or three in vitro tests recommended in other guidelines. Our evaluation of the chemical types used in hair dyes and comparison with other guidelines for testing a wide range of chemical substances, lead to the conclusion that potential genotoxic activity may effectively be determined by the application of a limited number of well-validated test systems that are capable of detecting induced gene mutations and structural and numerical chromosomal changes. We conclude that highly effective screening for genotoxicity of hair dyes can be achieved by the use of three assays, namely the bacterial gene mutation assay, the mammalian cell gene mutation assay (mouse lymphoma tk assay preferred) and the in vitro micronucleus assay. These need to be combined with metabolic activation systems optimised for the individual chemical types. Recent published evidence [D. Kirkland, M. Aardema, L. Henderson, L. Müller, Evaluation of the ability of a battery of three in vitro genotoxicity tests to discriminate rodent carcinogens and non-carcinogens. I. Sensitivity, specificity and relative predictivity, Mutat. Res. 584 (2005) 1-256] suggests that our recommended three tests will detect all known genotoxic carcinogens, and that increasing the number of in vitro assays further would merely reduce specificity (increase false positives). Of course there may be occasions when standard tests need to be modified to take account of special situations such as a specific pathway of biotransformation, but this should be considered as part of routine testing. It is clear that individual dyes and any other novel ingredients should be tested in this three-test battery. However, new products are formed on the scalp by reaction between the chemicals present in hair-dye formulations. Ideally, these should also be tested for genotoxicity, but at present such experiences are very limited. There is also the possibility that one component could mask the genotoxicity of another (e.g. by being more toxic), and so it is not practical at this time to recommend routine testing of complete hair-dye formulations as well. The most sensible approach would be to establish whether any reaction products within the hair-dye formulation penetrate the skin under normal conditions of use and test only those that penetrate at toxicologically relevant levels in the three-test in vitro battery. Recently published data [D. Kirkland, M. Aardema, L. Henderson, L. Müller, Evaluation of the ability of a battery of three in vitro genotoxicity tests to discriminate rodent carcinogens and non-carcinogens. I. Sensitivity, specificity and relative predictivity, Mutat. Res. 584 (2005) 1-256] suggest the three-test battery will produce a significant number of false as well as real positives. Whilst we are aware of the desire to reduce animal experiments, determining the relevance of positive results in any of the three recommended in vitro assays will most likely have to be determined by use of in vivo assays. The bone marrow micronucleus test using routes of administration such as oral or intraperitoneal may be used where the objective is extended hazard identification. If negative results are obtained in this test, then a second in vivo test should be conducted. This could be an in vivo UDS in rat liver or a Comet assay in a relevant tissue. However, for hazard characterisation, tests using topical application with measurement of genotoxicity in the skin would be more appropriate. Such specific site-of-contact in vivo tests would minimise animal toxicity burden and invasiveness, and, especially for hair dyes, be more relevant to human routes of exposure, but there are not sufficient scientific data available to allow recommendations to be made. The generation of such data is encouraged.
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Affiliation(s)
- D J Kirkland
- Covance Laboratories Limited, Otley Road, Harrogate HG3 1PY, UK.
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Kirkland D, Aardema M, Henderson L, Müller L. Evaluation of the ability of a battery of three in vitro genotoxicity tests to discriminate rodent carcinogens and non-carcinogens I. Sensitivity, specificity and relative predictivity. Mutat Res 2005; 584:1-256. [PMID: 15979392 DOI: 10.1016/j.mrgentox.2005.02.004] [Citation(s) in RCA: 486] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2004] [Revised: 02/07/2005] [Accepted: 02/25/2005] [Indexed: 12/23/2022]
Abstract
The performance of a battery of three of the most commonly used in vitro genotoxicity tests--Ames+mouse lymphoma assay (MLA)+in vitro micronucleus (MN) or chromosomal aberrations (CA) test--has been evaluated for its ability to discriminate rodent carcinogens and non-carcinogens, from a large database of over 700 chemicals compiled from the CPDB ("Gold"), NTP, IARC and other publications. We re-evaluated many (113 MLA and 30 CA) previously published genotoxicity results in order to categorise the performance of these assays using the response categories we established. The sensitivity of the three-test battery was high. Of the 553 carcinogens for which there were valid genotoxicity data, 93% of the rodent carcinogens evaluated in at least one assay gave positive results in at least one of the three tests. Combinations of two and three test systems had greater sensitivity than individual tests resulting in sensitivities of around 90% or more, depending on test combination. Only 19 carcinogens (out of 206 tested in all three tests, considering CA and MN as alternatives) gave consistently negative results in a full three-test battery. Most were either carcinogenic via a non-genotoxic mechanism (liver enzyme inducers, peroxisome proliferators, hormonal carcinogens) considered not necessarily relevant for humans, or were extremely weak (presumed) genotoxic carcinogens (e.g. N-nitrosodiphenylamine). Two carcinogens (5-chloro-o-toluidine, 1,1,2,2-tetrachloroethane) may have a genotoxic element to their carcinogenicity and may have been expected to produce positive results somewhere in the battery. We identified 183 chemicals that were non-carcinogenic after testing in both male and female rats and mice. There were genotoxicity data on 177 of these. The specificity of the Ames test was reasonable (73.9%), but all mammalian cell tests had very low specificity (i.e. below 45%), and this declined to extremely low levels in combinations of two and three test systems. When all three tests were performed, 75-95% of non-carcinogens gave positive (i.e. false positive) results in at least one test in the battery. The extremely low specificity highlights the importance of understanding the mechanism by which genotoxicity may be induced (whether it is relevant for the whole animal or human) and using weight of evidence approaches to assess the carcinogenic risk from a positive genotoxicity signal. It also highlights deficiencies in the current prediction from and understanding of such in vitro results for the in vivo situation. It may even signal the need for either a reassessment of the conditions and criteria for positive results (cytotoxicity, solubility, etc.) or the development and use of a completely new set of in vitro tests (e.g. mutation in transgenic cell lines, systems with inherent metabolic activity avoiding the use of S9, measurement of genetic changes in more cancer-relevant genes or hotspots of genes, etc.). It was very difficult to assess the performance of the in vitro MN test, particularly in combination with other assays, because the published database for this assay is relatively small at this time. The specificity values for the in vitro MN assay may improve if data from a larger proportion of the known non-carcinogens becomes available, and a larger published database of results with the MN assay is urgently needed if this test is to be appreciated for regulatory use. However, specificity levels of <50% will still be unacceptable. Despite these issues, by adopting a relative predictivity (RP) measure (ratio of real:false results), it was possible to establish that positive results in all three tests indicate the chemical is greater than three times more likely to be a rodent carcinogen than a non-carcinogen. Likewise, negative results in all three tests indicate the chemical is greater than two times more likely to be a rodent non-carcinogen than a carcinogen. This RP measure is considered a useful tool for industry to assess the likelihood of a chemical possessing carcinogenic potential from batteries of positive or negative results.
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Affiliation(s)
- David Kirkland
- Covance Laboratories Limited, Otley Road, Harrogate HG3 1PY, UK.
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Joosten HFP, van Acker FAA, van den Dobbelsteen DJ, Horbach GJMJ, Krajnc EI. Genotoxicity of hormonal steroids. Toxicol Lett 2004; 151:113-34. [PMID: 15177647 DOI: 10.1016/j.toxlet.2004.01.018] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2004] [Revised: 01/06/2004] [Accepted: 01/06/2004] [Indexed: 10/26/2022]
Abstract
Hormonal steroids have a widespread use in medicine and their side effects are continuously debated. The possible genotoxic activity of steroids has been the subject of many investigations. The natural estrogens estradiol, estrone and estriol are generally negative in the ICH core battery of tests, but several positive results have been obtained when using additional endpoints of genotoxicity. The genotoxic activity of the 4-hydroxy metabolites of estradiol and estrone is well established. The synthetic steroidal estrogens have a comparable profile of negative and positive test results. Cyproterone acetate and some of its analogues have a special position within the group of progestins. Their genotoxic potential has been established. Other progestins are generally negative in the routine tests. Anti-glucocorticoids, anti-progestins, corticosteroids, androgens, anabolics and anti-androgens appear to be devoid of genotoxic activities. The genotoxic potential of estradiol, estrone and cyproterone acetate with its analogues may play no role under normal physiological and therapeutic conditions. The metabolic conditions that are needed for the formation of DNA-reactive metabolites and oxygen radicals may not be present in humans. Epidemiological cancer data seem to support this view. The importance of thresholds in the dose-effect-relationship of genotoxicity data and their use in risk assessment is discussed.
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Affiliation(s)
- H F P Joosten
- Department of Toxicology and Drug Disposition, Organon, P.O. Box 20, 5340 BH Oss, The Netherlands.
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Muñoz ER, Mazar Barnett B. The rodent carcinogens 1,4-dioxane and thiourea induce meiotic non-disjunction in Drosophila melanogaster females. Mutat Res 2002; 517:231-8. [PMID: 12034324 DOI: 10.1016/s1383-5718(02)00083-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The ability of the rodent carcinogens 1,4-dioxane (DX) and thiourea (TU) to induce meiotic non-disjunction (ND) was assessed in 3- and 6-day-old Drosophila melanogaster females. The chemicals were administered orally and three 24 h and one 48 h broods were obtained after mating, to sample oocytes treated in increasingly earlier stages of development. The broods represent mainly mature oocytes (brood I), nearly mature oocytes (brood II), early oocytes (brood III) and very early oocytes (brood IV). The toxicity of DX increased with dose (1% (not toxic), 1.5, 2, 3, 3.5%) as well as a reduction in fecundity which was moderate. Induction of ND in mature oocytes was positive with 2, 3 and 3.5% concentrations and was not related to dose. In immature oocytes it was also positive though already at the lowest concentration tested (1%), suggesting a sensitivity higher than that of mature oocytes. TU at 0.10-10%, did not affect viability, but since fecundity was seriously impaired at high doses, ND was not assessed beyond the 1.5% concentration. TU also induced ND in mature and in immature oocytes; neither a threshold nor a dose effect was detected. The response of mature oocytes was lower than that of immature oocytes. TU induced increases of ND in the earliest cells tested in a more consistent fashion than DX. The data clearly show that both chemicals induced ND in mature oocytes and in the three subsets in which immature oocytes were fractionated. Though toxicity may play a significant unspecific role in the induction of chromosome malsegregation by DX and TU, the induction of ND at low doses, moderately toxic to the oocytes, suggests that the interaction with specific targets contributed to the results obtained.
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Affiliation(s)
- Enzo R Muñoz
- Radiobiología, Comisión Nacional de Energía Atómica, Av. Gral. Paz 1499, 1650 San Martín, Buenos Aires, Argentina.
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Kennedy GL. Biological effects of acetamide, formamide, and their mono and dimethyl derivatives: an update. Crit Rev Toxicol 2001; 31:139-222. [PMID: 11303553 DOI: 10.1080/200140911116861] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- G L Kennedy
- Haskell Laboratory for Toxicology and Industrial Medicine, DuPont Company, Newark, Delaware, USA
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Martelli A, Mereto E, Ghia M, Orsi P, Allavena A, De Pascalis CR, Brambilla G. Induction of micronuclei and of enzyme-altered foci in the liver of female rats exposed to progesterone and three synthetic progestins. Mutat Res 1998; 419:33-41. [PMID: 9804880 DOI: 10.1016/s1383-5718(98)00122-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Progesterone (PG) and three structurally similar synthetic progestins-norethisterone (NE), allylestrenol (AE), and dydrogesterone (DG)-have been compared for their ability to induce the formation of micronuclei and of enzyme-altered foci in the liver of female rats. In the micronucleus assay, carried out in rats given a single p.o. dose of 100 mg kg-1 3 days before partial hepatectomy and sacrificed for cell sampling 2 days later, the frequency of micronucleated hepatocytes was 3.5-fold higher than in controls with PG, 2.8-fold with DG, 2.2-fold with NE and 2.1-fold with AE, but the increase was statistically significant only for PG. In the liver foci assay, performed to evaluate the tumor initiating activity of p. o. dosing with 100 mg kg-1 once a week for 6 successive weeks, the values of the number and area of gamma-glutamyltranspeptidase-positive foci were, as compared to controls, 15.9- and 100-fold higher with NE, and 13.9- and 52-fold higher with AE, but only the increase of area produced by NE was statistically significant; PG and DG did not display in this test any activities. Considered together with previous findings, these results suggest that NE might be biotransformed in the liver into reactive species and thus behave as a weak genotoxic agent.
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Affiliation(s)
- A Martelli
- Department of Internal Medicine, Division of Clinical Pharmacology and Toxicology, University of Genoa, I-16132, Genoa, Italy
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Sasaki YF, Saga A, Akasaka M, Ishibashi S, Yoshida K, Su YQ, Matsusaka N, Tsuda S. Organ-specific genotoxicity of the potent rodent colon carcinogen 1,2-dimethylhydrazine and three hydrazine derivatives: difference between intraperitoneal and oral administration. Mutat Res 1998; 415:1-12. [PMID: 9711257 DOI: 10.1016/s1383-5718(98)00002-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We used a modification of the alkaline single cell gel electrophoresis (SCG) (Comet) assay to test the in vivo genotoxicity of four hydrazine derivatives--1,2-dimethylhydrazine (SDMH), 1,1-dimethylhydrazine (UDMH), hydrazine (HZ), and procarbazine (PCZ)--in mouse liver, lung, kidney, brain, and bone marrow, and in the mucosa of stomach, colon, and bladder. Mice were sacrificed 3 and 24 h after intra-peritoneal (i.p.) and oral (p.o.) administration. SDMH at 20 mg/kg i.p. yielded statistically significant DNA damage in all tested organs except for lung. In the gastrointestinal tract, SDMH was genotoxic in the stomach and the colon after i.p. treatment but only in the colon after 20 and 30 mg/kg p.o. treatment. UDMH at 50 mg/kg i.p. yielded DNA damage in the liver and lung at 3 h. PCZ at 200 mg/kg i.p. caused DNA damage in the liver, kidney, lung, brain, and bone marrow. UDMH and PCZ were positive in the stomach and colon p.o. but not by i.p. treatment. HZ at 100 mg/kg yielded DNA damage in the stomach, liver, and lung when given i.p. and in the brain when p.o. Thus, the administration route is important when evaluating organ-specific genotoxicity in multiple organs.
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Affiliation(s)
- Y F Sasaki
- Laboratory of Genotoxicity, Faculty of Chemical and Biological Engineering, Hachinohe National College of Technology, Aomori, Japan.
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Battershill JM, Fielder RJ. Mouse-specific carcinogens: an assessment of hazard and significance for validation of short-term carcinogenicity bioassays in transgenic mice. Hum Exp Toxicol 1998; 17:193-205. [PMID: 9617631 DOI: 10.1177/096032719801700401] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
1. The International Conference on the Harmonisation of Technical Requirements for the Registration of Pharmaceuticals for human use (ICH) has agreed that bioassay data from only one species, the rat, supported by appropriate mutagenicity and pharmacokinetic data and also information from new (unvalidated) short term in vivo screening tests for potential carcinogenicity, could be used for the licensing of human medicines. This proposal has been supported by reviews of the utility of testing pharmaceuticals in the mouse which have concluded that the mouse bioassay contributes little to regulatory decisions. The current review was undertaken to identify 'genuine' mouse-specific carcinogens using the Gold Carcinogenicity Potency Database (CPD) for the initial identification of potential mouse-specific carcinogens from published literature. Hazard assessments were completed for these chemicals with particular attention focused on the 'genuine' mouse-specific carcinogens. The significance of such chemicals has been discussed together with consideration of on-going work on the validation of short-term carcinogenicity bioassays using transgenic mice. 2. Seventy-six potential mouse specific carcinogens were identified through the Gold Carcinogenicity Potency Database. Following more detailed consideration a total of ten chemicals were excluded from further consideration (three were multispecies carcinogens, five were considered to be non-carcinogenic in the mouse, and the data for two were uninterpretable). The review focused on the remaining 66 chemicals. There was equivocal evidence of carcinogenicity to the rat for 28 chemicals and inadequate data for a further 23 chemicals. Fifteen 'genuine' mouse-specific carcinogens were identified. These 15 chemicals comprise two genotoxic mouse-specific carcinogens (N-methylolacrylamide (924-42-5), 2,6-Dichloro-p-phenylenediamine (609-20-1); five non-genotoxic mouse-specific carcinogens 2-Aminobiphenyl.HCl (2185-92-4), Captan (133-06-2), Dieldrin (60-57-7), Diethylhexyladipate (103-23-1), and Probenicid (57-66-9); five mouse-specific carcinogens with equivocal evidence of mutagenicity were identified; (2,4-diaminophenol.2HCl (137-09-7), Dipyrone (68-89-3), Ozone (10028-15-6), Vinylidene chloride (75-35-4), and Zearalenone (17924-92-4)), and three mouse-specific carcinogens with inadequate mutagenicity data (Benzaldehyde (100-52-7), Piperonyl sulphoxide (120-62-7), Ripazepam (26308-28-1)). 3. It is suggested that the two genotoxic mouse carcinogens would have been considered as potential carcinogens in the absence of a mouse bioassay. Of the five non-genotoxic mouse-specific carcinogens; three induced tumours in mouse liver only and are considered as being of low potential hazard to human health. The remaining two chemicals would have been missed in the absence of a mouse bioassay (2-aminobiphenyl (2185-92-4) and captan (133-06-2)) and thus are good candidates for evaluation in the short term bioassays in transgenic mice currently being validated. 4. The hardest group of mouse-specific carcinogens to evaluate are those for which there is equivocal or inadequate mutagenicity data. The difficulty in evaluating these particular chemicals emphasises the need for adequate mutagenicity data in addition to adequate carcinogenicity data in order to assess potential hazards to human health. Hazard assessments and a consideration of the potential role for short-term bioassays in transgenic mice for the eight chemicals in this subgroup are presented. 5. A number of general conclusions have been derived from this review. Firstly, there are insufficient published genotoxicity data to allow a full assessment fo mutagenic potential for 57/76 of the potential mouse-specific carcinogens identified from the CPD. This is surprising given the clear value of such data in interpreting bioassay results and the much greater resources required for carcinogenicity bioassays. (ABSTRACT TRUNCATED)
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Abstract
Birth defects cause a myriad of societal problems and place tremendous anguish on the affected individual and his or her family. Current estimates categorize about 3% of all newborn infants as having some form of birth defect or congenital anomaly. As more precise means of detecting subtle anomalies become available this estimate, no doubt, will increase. Even though birth defects have been observed in newborns throughout history, our knowledge about the causes and mechanisms through which these defects are manifested is limited. For example, it has been estimated that around 20% of all birth defects are due to gene mutations, 5-10% to chromosomal abnormalities, and another 5-10% to exposure to a known teratogenic agent or maternal factor [D.A. Beckman, R.L. Brent, Mechanisms of teratogenesis. Ann. Rev. Pharmacol. Toxicol. 24 (1984) 483-500; K. Nelson, L.B. Holmes Malformations due to presumed spontaneous mutations in newborn infants, N. Engl. J. Med. 320 (1989) 19-23.]. Together, these percentages account for only 30-40%, leaving the etiology of more than half of all human birth defects unexplained. It has been speculated that environmental factors account for no more than one-tenth of all congenital anomalies [D.A. Beckman, R.L. Brent, Mechanisms of teratogenesis, Ann. Rev. Pharmacol. Toxicol. 24 (1984) 483-500]. Furthermore, since there is no evidence in humans that the exposure of an individual to any mutagen measurably increases the risk of congenital anomalies in his or her offspring' [J.F. Crow, C. Denniston, Mutation in human populations, Adv. Human Genet. 14 (1985) 59-121; J.M. Friedman, J.E. Polifka, Teratogenic Effects of Drugs: A Resource for Clinicians (TERIS). The John Hopkins University Press, Baltimore, 1994], the mutagenic activity of environmental agents and drugs as a factor in teratogenesis has been given very little attention. Epigenetic activity has also been given only limited consideration as a mechanism for teratogenesis. As new molecular methods are developed for assessing processes associated with teratogenesis, especially those with a genetic or an epigenetic basis, additional environmental factors may be identified. These are especially important because they are potentially preventable. This paper examines the relationships between chemicals identified as human teratogens (agents that cause birth defects) and their mutagenic activity as evaluated in one or more of the established short-term bioassays currently used to measure such damage. Those agents lacking mutagenic activity but with published evidence that they may otherwise alter the expressions or regulate interactions of the genetic material, i.e. exhibit epigenetic activity, have likewise been identified. The information used in making these comparisons comes from the published literature as well as from unpublished data of the U.S. National Toxicology Program (NTP).
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Affiliation(s)
- J B Bishop
- Laboratory of Toxicology, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA.
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Mitchell AD, Auletta AE, Clive D, Kirby PE, Moore MM, Myhr BC. The L5178Y/tk+/- mouse lymphoma specific gene and chromosomal mutation assay a phase III report of the U.S. Environmental Protection Agency Gene-Tox Program. Mutat Res 1997; 394:177-303. [PMID: 9434856 DOI: 10.1016/s1383-5718(97)00115-0] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The L5178Y/tk+/- (-)3.7.2C mouse lymphoma assay (MLA) which detects mutations affecting the heterozygous thymidine kinase (tk) locus is capable of responding to chemicals acting as clastogens as well as point mutagens. Improvements in the assay to enhance detection of this spectrum of genetic events are summarized, and criteria for evaluating the data are defined. Using these criteria, the Phase III Work Group reviewed and evaluated literature containing MLA results published from 1976 through 1993. The data base included 602 chemicals of which 343 were evaluated as positive, 44 negative, 18 equivocal, 54 apparently inappropriate for evaluation in this test system with the published protocols, and 142 that were inadequately tested, and thus a definitive call could not be made. The overall performance of the assay is summarized by chemical class, and the outcome of testing 260 chemicals in the MLA is compared with Gene-Tox and National Toxicology Program evaluations of rodent carcinogenesis bioassay results for the same chemicals. Based on the Work Group's evaluation of published MLA data for chemicals that were considered adequately tested, it is concluded that for most chemicals the L5178Y/tk+/- mouse lymphoma assay is eminently well suited for genotoxicity testing and for predicting the potential for carcinogenicity.
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Affiliation(s)
- A D Mitchell
- Genesys Research, Incorporated, Research Triangle Park, NC 27709, USA
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29
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Morita T, Asano N, Awogi T, Sasaki YF, Sato S, Shimada H, Sutou S, Suzuki T, Wakata A, Sofuni T, Hayashi M. Evaluation of the rodent micronucleus assay in the screening of IARC carcinogens (groups 1, 2A and 2B) the summary report of the 6th collaborative study by CSGMT/JEMS MMS. Collaborative Study of the Micronucleus Group Test. Mammalian Mutagenicity Study Group. Mutat Res 1997; 389:3-122. [PMID: 9062586 DOI: 10.1016/s1383-5718(96)00070-8] [Citation(s) in RCA: 230] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
To assess the correlation between micronucleus induction and human carcinogenicity, the rodent micronucleus assay was performed on known and potential human carcinogens in the 6th MMS/CSGMT collaborative study. Approximately 100 commercially available chemicals and chemical groups on which there was little or no micronucleus assay data were selected from IARC (International Agency for Research on Cancer) Groups 1 (human carcinogen), 2A (probable human carcinogen) and 2B (possible human carcinogen). As minimum requirements for the collaborative study, 5 male mice were treated by intraperitoneal injection or oral gavage once or twice with each chemical at three dose levels, and bone marrow and/or peripheral blood was analyzed. Five positives and 2 inconclusives out of 13 Group 1 chemicals, 7 positives and 5 inconclusives of 23 Group 2A chemicals, and 26 positives and 6 inconclusives of 67 Group 2B chemicals were found. Such low positive rates were not surprising because of a test chemical selection bias, and we excluded well-known micronucleus inducers. The overall evaluation of the rodent micronucleus assay was based on the present data combined with published data on the IARC carcinogens. After merging, the positive rates for Groups 1, 2A and 2B were 68.6, 54.5 and 45.6%, respectively. Structure-activity relationship analysis suggested that the micronucleus assay is more sensitive to the genetic toxicity of some classes of chemicals. Those to which it is sensitive consist of (1) aziridines and bis(2-chloroethyl) compounds; (2) alkyl sulfonate and sulfates; (3) acyl-type N-nitroso compounds; (4) hydrazines; (5) aminobiphenyl and benzidine derivatives; and (6) azo compounds. Those to which it is less sensitive consist of (1) dialkyl type N-nitroso compounds; (2) silica and metals and their compounds; (3) aromatic amines without other functional groups; (4) halogenated compounds; and (5) steroids and other hormones. After incorporation of structure-activity relationship information, the positive rates of the rodent micronucleus assay became 90.5, 65.2 and 60.0% for IARC Groups 1, 2A and 2B, respectively. Noteworthy was the tendency of the test to be more sensitive to those carcinogens with stronger evidence human carcinogenicity.
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Affiliation(s)
- T Morita
- Tsukuba Research Laboratories, Nippon Glaxo Ltd., Japan
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30
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Sasaki YF, Tsuda S, Izumiyama F, Nishidate E. Detection of chemically induced DNA lesions in multiple mouse organs (liver, lung, spleen, kidney, and bone marrow) using the alkaline single cell gel electrophoresis (Comet) assay. Mutat Res 1997; 388:33-44. [PMID: 9025790 DOI: 10.1016/s1383-5718(96)00133-7] [Citation(s) in RCA: 106] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The effect of 2 model chemical mutagens on DNA was evaluated with the alkaline single cell gel electrophoresis (SCG) (Comet) assay in 5 mouse organs--liver, lung, kidney, spleen and bone marrow. Mice were sacrificed 3 and 24 h after the administration of the direct mutagen ethyl nitrosourea (ENU) or the liver-targeting promutagen p-dimethylaminoazobenzene (DAB). Each organ was minced, suspended at a concentration of 1 g/ml in chilled homogenizing buffer (pH 7.5) containing 0.075 M NaCl and 0.024 M Na2EDTA, homogenized gently using a Potter-type homogenizer at 500-800 rpm set in ice, and then centrifuged nuclei were used for the alkaline SCG assay. ENU induced DNA damage in cells all of the organs studied DAB, on the other hand, produced a positive response in the liver only. We suggest that it may be possible to use the alkaline SCG assay using a homogenization technique to detect the genotoxicity of chemicals in vivo in their target organs.
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Affiliation(s)
- Y F Sasaki
- Laboratory of Genotoxicity, Faculty of Chemical and Biological Engineering, Hachinohe National College of Technology, Aomori, Japan.
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31
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McGregor D, Riach C, Cattanach P, Edwards I, Shepherd W, Caspary W. Mutagenic responses of L5178Y mouse cells at the tk and hprt loci. Toxicol In Vitro 1996; 10:643-7. [DOI: 10.1016/s0887-2333(96)90030-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/23/1996] [Indexed: 11/15/2022]
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32
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Mirkova ET. Activities of the rodent carcinogens thioacetamide and acetamide in the mouse bone marrow micronucleus assay. Mutat Res 1996; 352:23-30. [PMID: 8676911 DOI: 10.1016/0027-5107(95)00169-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Thioacetamide is confirmed as active in the mouse bone marrow micronucleus assay, following single oral administration to both sexes of two different strains of mice (C57BL/6, BALB/c) in five separate experiments. Acetamide is shown to be consistently and clearly negative as a micronucleus-inducing agent in mouse bone marrow in four repeated assays using different sexes of two strains of mice (C57BL/6, CBA). The present findings support the adequacy of the limited micronucleus test protocol (male animals, two sampling times) for the efficient detection of genotoxic rodent carcinogens in this assay.
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Affiliation(s)
- E T Mirkova
- National Center of Hygiene, Ministry of Health, Sofia, Bulgaria
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33
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Glatt H. Comparison of common gene mutation tests in mammalian cells in culture: a position paper of the GUM Commission for the Development of Guidelines for Genotoxicity Testing. Mutat Res 1994; 313:7-20. [PMID: 7519313 DOI: 10.1016/0165-1161(94)90028-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
In gene mutation tests a decision concerning mutations is made on the basis of hereditary functional changes. In terms of the large amount of data available, the most suitable tests for routine testing in mammalian cells in culture are the tests for acquisition of 6-thioguanine resistance in Chinese hamster cells (V79 and CHO) and for acquisition of alpha,alpha,alpha-trifluorothymidine resistance in the mouse lymphoma line L5178Y TK+/- 3.7.2C. The molecular bases, peculiarities, advantages and disadvantages of these systems will be presented. Which system is to be preferred in any particular case depends among other things on the purpose of the study and the extent to which a technically competent performance of these comparatively exacting tests can be guaranteed.
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Affiliation(s)
- H Glatt
- Department of Toxicology, University of Mainz, Germany
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34
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Benigni R, Andreoli C. Rodent carcinogenicity and toxicity, in vitro mutagenicity, and their physical chemical determinants. Mutat Res 1993; 297:281-92. [PMID: 7692274 DOI: 10.1016/0165-1110(93)90020-n] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
In this paper, we considered rodent carcinogenicity and toxicity, and four in vitro mutagenicity systems, and we made a global comparison between their different response profiles to a common set of 297 chemicals. This analysis is complemented with a study of the physical chemical properties of active and inactive compounds in the different systems. A clearcut separation between the different classes of toxicological end-points (carcinogenicity, in vivo toxicity, in vitro carcinogenicity) was evident. The observed lack of association between carcinogenicity and toxicity supports the validity of the rodent bioassays; this is contrary to the position that the positive results obtained are due mainly to the use of excessive doses that exert cytotoxic effects. We found substantial consistency in the responses of the in vivo toxicity systems (maximum tolerated dose and LD50), but we also found that remarkable differences exist between the in vitro mutagenicity assay systems. The study of the structure-activity relationships showed that: (a) the hydrophobic-electronic properties of the chemicals influence rodent carcinogenicity, with the tendency of carcinogens to be more electrophilic and more hydrophobic than non-carcinogens; (b) steric effects are implied in in vitro mutagenicity, bulkier molecules being less mutagenic than smaller molecules; (c) no clear association between in vivo toxicity and physical chemical properties was apparent. The differences between carcinogenicity and in vitro mutagenicity may hypothetically be related to their different experimental procedures. The relatively short treatment of in vitro mutagenicity requires that chemicals penetrate easily into the cells, and are well dissolved into the aqueous medium, size and hydrophilicity thus being critical for the action of the chemicals. The size of the molecules is not critical in the long-term rodent carcinogenicity experiments, where other factors, like bioaccumulation (hydrophobicity) and electronic reactivity, become essential.
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Affiliation(s)
- R Benigni
- Istituto Superiore di Sanitá, Laboratory of Comparative Toxicology and Ecotoxicology, Rome, Italy
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35
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Dearfield KL, Stack HF, Quest JA, Whiting RJ, Waters MD. A survey of EPA/OPP and open literature data on selected pesticide chemicals tested for mutagenicity. I. Introduction and first ten chemicals. Mutat Res 1993; 297:197-233. [PMID: 7692272 DOI: 10.1016/0165-1110(93)90018-i] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Parties interested in registering a pesticide chemical with the U.S. Environmental Protection Agency's (USEPA's) Office of Pesticide Programs (OPP) must submit toxicity information to support the registration. Mutagenicity data are a part of the required information that must be submitted. This information is available to the public via Freedom of Information requests to the OPP. However, it is felt that this information would be more effectively and widely disseminated if presented in a published medium. Beginning with this publication, sets of mutagenicity data on pesticide chemicals will be periodically published in the Genetic Activity Profile (GAP) format. In addition, mutagenicity data extracted from the currently available open literature is also presented to provide a more complete database and to allow comparisons between the OPP-submitted data and other publicly available information.
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Affiliation(s)
- K L Dearfield
- U.S. Environmental Protection Agency, Office of Pesticide Programs, Washington, DC 20460
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36
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Oberly TJ, Michaelis KC, Rexroat MA, Bewsey BJ, Garriott ML. A comparison of the CHO/HGPRT+ and the L5178Y/TK+/- mutation assays using suspension treatment and soft agar cloning: results for 10 chemicals. Cell Biol Toxicol 1993; 9:243-57. [PMID: 8299003 DOI: 10.1007/bf00755603] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The mouse lymphoma assay (MLA) and Chinese hamster ovary (CHO) cell assay are sensitive indicators of mutagenicity. The CHO assay has been modified technically to permit treatment in suspension and soft agar cloning comparable to the MLA. This methodology eliminates the risk of metabolic cooperation and the trauma of trypsinization. In addition, a larger population of cells can be treated and cloned for mutant selection. In order to compare the effectiveness of the test systems, 10 chemicals were evaluated for the induction of forward mutations in the CHO and MLA. Several of these chemicals have been reported as clastogenic; therefore, abbreviated colony sizing was performed to gauge the extent of genetic damage to the MLA cells. Both test systems detected benzo[a]pyrene, mitomycin C, acridine orange, and proflavin, and, with the exception of proflavin, more large colonies were present than small colonies. The suspect clastogen, phenytoin, was not mutagenic in the MLA and produced inconclusive results in the CHO. Ethidium bromide, a clastogen and a bacterial mutagen, was not mutagenic in either the MLA or CHO. Four compounds (p-aminophenol, benzoin, methoxychlor, and pyrene) were positive in the MLA, generally inducing a large number of small colonies, while demonstrating no mutagenic activity in the CHO assay. They have also been shown to be generally nongenotoxic in other test systems. Overall, the modified CHO assay did not appear to be better than the MLA for the detection of mutagenic agents. However, the MLA does appear to have lower specificity.
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Affiliation(s)
- T J Oberly
- Toxicology Research Laboratories, Lilly Research Laboratories, Greenfield, IN 46140
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37
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Chan PC, Huff J, Haseman JK, Quest JA, Hall W. Liver carcinogenesis by methyl carbamate in F344 rats and not in B6C3F1 mice. Jpn J Cancer Res 1992; 83:258-63. [PMID: 1582888 PMCID: PMC5918802 DOI: 10.1111/j.1349-7006.1992.tb00097.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Short-term and long-term carcinogenicity of methyl carbamate (MCB) was evaluated in F344 rats and B6C3F1 mice. In experiments lasting 6, 12, and 18 months, MCB was given in water by gavage to groups of 10 male and 10 female rats at 0 or 400 mg/kg body weight, 5 days per week, and to similar groups of mice at 0 or 1,000 mg/kg. At 6 months, MCB induced atypical mitoses, cytologic alterations, cytomegaly, pigmentation, necrosis, and neoplastic nodules of the liver in rats. At 12 and 18 months, carcinomas of the liver were induced by MCB in 80-90% of male rats and in 60-80% of female rats. None was observed in control rats or in mice. In the 2-year studies, MCB was given to groups of 50 male and 50 female rats at 0, 100, or 200 mg/kg and to similar groups of mice at 0, 500, or 1,000 mg/kg, 5 days/week. Chronic focal inflammation, cytologic alteration, hyperplasia, and neoplastic nodules and carcinomas (200 mg/kg groups only) of the liver were induced by MCB in rats. Liver tumor incidence data for combined experiments in rats were: males--5% in controls, 0% in 100 mg/kg group, 14% in 200 mg/kg group, and 77% in 400 mg/kg group; females--5% in controls, 0% in controls, 0% in 100 mg/kg group, 12% in 200 mg/kg group, and 63% in 400 mg/kg group. MCB was not shown to be carcinogenic in mice.
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Affiliation(s)
- P C Chan
- National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709
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38
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Scott D, Galloway SM, Marshall RR, Ishidate M, Brusick D, Ashby J, Myhr BC. International Commission for Protection Against Environmental Mutagens and Carcinogens. Genotoxicity under extreme culture conditions. A report from ICPEMC Task Group 9. Mutat Res 1991; 257:147-205. [PMID: 2005937 DOI: 10.1016/0165-1110(91)90024-p] [Citation(s) in RCA: 159] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- D Scott
- Cancer Research Campaign Laboratories, Paterson Institute for Cancer Research, Manchester, Great Britain
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39
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Abstract
A construction of batteries of short-term tests (STTs) is described which is based on a classification of 73 chemicals in regard to their carcinogenicity. The 73 chemicals were studied within the U.S. National Toxicology Program (Ashby and Tennant, 1988). The batteries are validated using the classification of 35 additional chemicals. They are defined by logically structured combinations of rules. The single rules are defined by the z-scores of the logarithmic values of the limiting doses obtained from the 4 in vitro STTs used in the study by Ashby and Tennant. The limiting dose is defined as the lowest effective dose or the highest ineffective dose (Waters et al., 1987). The batteries are constructed by minimizing the number of disagreements with the classification by Ashby and Tennant. Compared with the results obtained from single STTs, 2 batteries of 3 STTs have higher concordances with the carcinogenicity data, namely 70% for the NTP data and 74-77% for the independent test data. In addition, a theoretical result shows that the proposed battery design, for a large enough learning set of chemicals, leads to results which are replicated with high probability on a large enough validation set. Based on the first results obtained with a limited number of chemicals it is concluded that the knowledge-based battery design is worth further development.
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Affiliation(s)
- R Buzzi
- Comparative Physiology Laboratory, Swiss Federal Institute of Technology, Zurich
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40
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Abstract
This article reviews approximately 700 results reported in the literature with 32 chromium compounds assayed in 130 short-term tests, using different targets and/or genetic end-points. The large majority of the results obtained with Cr(VI) compounds were positive, as a function of Cr(VI) solubility and bioavailability to target cells. On the other hand, Cr(III) compounds, although even more reactive than Cr(VI) with purified nucleic acids, did not induce genotoxic effects in the majority of studies using intact cells. Coupled with the findings of metabolic studies, the large data-base generated in short-term test systems provides useful information for predicting and interpreting the peculiar patterns of Cr(VI) carcinogenicity.
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Affiliation(s)
- S De Flora
- Institute of Hygiene and Preventive Medicine, University of Genoa, Italy
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41
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Myhr B, McGregor D, Bowers L, Riach C, Brown AG, Edwards I, McBride D, Martin R, Caspary WJ. L5178Y mouse lymphoma cell mutation assay results with 41 compounds. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 1990; 16 Suppl 18:138-167. [PMID: 2128695 DOI: 10.1002/em.2850160506] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Forty-one chemicals were tested for their abilities to induce trifluorothymidine resistance in L5178Y mouse lymphoma (MOLY) cells. These chemicals were included in the National Toxicology Program's evaluation of four in vitro short-term toxicity assays for predicting carcinogenicity in the rodent bioassay. Of the 41 chemicals examined for this report, 8 were equivocal in the rodent bioassay, and 7 were questionable in- the MOLY assay. If these chemicals are eliminated from an analysis of concordance, the remaining 26 chemicals lead to a concordance of 69% with a sensitivity of 71%. The specificity could not be determined because only two non-carcinogens were detected.
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Affiliation(s)
- B Myhr
- Department of Molecular and Cellular Toxicology, Hazleton Laboratories of America, Kensington, Maryland
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42
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Blazak WF, Los FJ, Rudd CJ, Caspary WJ. Chromosome analysis of small and large L5178Y mouse lymphoma cell colonies: comparison of trifluorothymidine-resistant and unselected cell colonies from mutagen-treated and control cultures. Mutat Res 1989; 224:197-208. [PMID: 2507912 DOI: 10.1016/0165-1218(89)90156-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Mutagenesis assays at the thymidine kinase (TK) locus in L5178Y mouse lymphoma cells frequently yield mutant colonies with a bimodal size distribution. The objectives of this study were to determine whether a relationship exists between mutant colony size and chromosomal aberrations and whether the colony-size distributions obtained from this assay can indicate the clastogenic activity of a test chemical. Cells from 8 different types of L5178Y mouse lymphoma cell colonies were examined for chromosomal abnormalities within 10 cell generations after colony isolation. The colonies included small (sigma) and large (lambda) unselected cell (UC) and trifluorothymidine-resistant (TFTr) colonies derived from TK +/- cell cultures treated with the solvent dimethyl sulfoxide (DMSO) or hycanthone methanesulfonate (HYC). Chromosome abnormalities were present in cells from 12% (7/60) of the UC colonies, but there was no apparent relationship between colony diameter and the presence of chromosomal abnormalities. Abnormalities affecting chromosome 11, which is believed to be the site of the TK gene, were not observed in cells from UC colonies. Abnormalities affecting chromosome 11 were observed only in cells from sigma-TFTr colonies irrespective of whether they were spontaneous (5/15 colonies) or induced by HYC (4/15 colonies). Overall, 30% (9/30) of sigma-TFTr colonies had cells with an abnormal chromosome 11 and 10% (3/30) had abnormalities affecting other chromosomes. Abnormalities affecting chromosome 11 were not observed in cells from lambda-TFTr colonies (0/30 colonies). The observation of only 30% of sigma-TFTr colonies with chromosome damage affecting chromosome 11 indicates that other mechanisms, in addition to chromosome damage at the level of resolution used in this study (i.e., 200-300 chromosome bands). contribute to small TFTr colony size.
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Affiliation(s)
- W F Blazak
- Cellular and Genetic Toxicology Department, SRI International, Menlo Park, CA 94025
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43
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Affiliation(s)
- P Arni
- Ciba-Geigy Ltd., Basle, Switzerland
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44
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Caspary WJ, Langenbach R, Penman BW, Crespi C, Myhr BC, Mitchell AD. The mutagenic activity of selected compounds at the TK locus: rodent vs. human cells. Mutat Res 1988; 196:61-81. [PMID: 3292900 DOI: 10.1016/0165-1110(88)90028-0] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The mutagenic (TFT resistance) and toxic responses of mouse lymphoma (MOLY) L5178Y cells and human lymphoblast (HULY) TK6 cells were compared for 13 chemicals. The mutagenic activities of 8 of the 13 chemicals (62%) examined in the HULY and MOLY assays are in agreement - the results being judged positive in both assays. However, a dramatic difference is observed when the two conditions of metabolic activation are considered separately; the overall concordance of 8/13 has been achieved by combining a 13/13 (100%) agreement in the absence of S9 with a 1/6 (17%) agreement in the presence of S9. In the absence of S9, the concentration ranges, lowest significant doses, and shapes of the concentration-response curves for both toxicity and mutagenicity were similar in spite of the differences in exposure times (4 h for MOLY, 20 for HULY) and expression times (2 days for MOLY, 3 days for HULY). The general agreement observed in the absence of S9 contrasted with the differences manifested in its presence. 6 compounds which were negative in the absence of S9 were tested in both the MOLY and HULY assays in the presence of S9. Of the 6 chemicals, only 1 was positive in both MOLY and HULY under the latter condition; 4 others were positive in MOLY and negative in HULY whereas 1 was positive in HULY and negative in MOLY.
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Affiliation(s)
- W J Caspary
- Cellular and Genetic Toxicology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709
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45
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Caspary WJ, Lee YJ, Poulton S, Myhr BC, Mitchell AD, Rudd CJ. Evaluation of the L5178Y mouse lymphoma cell mutagenesis assay: quality-control guidelines and response categories. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 1988; 12 Suppl 13:19-36. [PMID: 3416839 DOI: 10.1002/em.2860120503] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A data-based approach to formulating quality-control criteria for the mouse lymphoma cell forward mutation assay is described. Quality-control guidelines for solvent controls, positive controls, and compound-treated cultures were developed based on analysis of over 800 experiments. Frequency distributions of experimental parameters of control cultures, such as mutant frequencies, cloning efficiencies, and suspension growths, were examined. Cloning efficiency and relative total growth affected the variability only when the test chemical was highly toxic. This information was used to generate the quality-control criteria, which were applied to an experiment before it was evaluated for a response. The response categories for classifying the effect of test chemicals on the assay system are defined in terms of (1) the statistically significant differences in average mutant frequency between solvent control cultures and cultures exposed to a chemical and (2) the trend of the dose-related responses.
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Affiliation(s)
- W J Caspary
- Cellular and Genetic Toxicology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
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46
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Caspary WJ, Daston DS, Myhr BC, Mitchell AD, Rudd CJ, Lee PS. Evaluation of the L5178Y mouse lymphoma cell mutagenesis assay: interlaboratory reproducibility and assessment. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 1988; 12 Suppl 13:195-229. [PMID: 3416840 DOI: 10.1002/em.2860120506] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The L5178Y mouse lymphoma cell mutagenesis assay is used to detect the mutagenic activity of chemicals in a mammalian cell system. To evaluate this assay we compared the results of assays performed independently on 63 chemicals by laboratories at SRI International and Litton Bionetics, Inc. The two laboratories used similar protocols. The solvent and positive control mutant frequencies and cloning efficiencies obtained by the two laboratories were similar, which justified the use of the same quality-control criteria and analytical procedures for analyzing the results from both laboratories. The rate of concordance between the two laboratories was 92% for tests in the absence of S9 activation and 95% for tests in its presence. The results of the assays agreed for 57 of the 63 chemicals; three chemicals could not be compared because there were questionable calls in at least one of the laboratories; the results disagreed for the three remaining chemicals. The concordance rate for these overall assay evaluations was 95%. The interlaboratory concordance rates were similar to concordance rates for replicate experiments within the laboratories (96% at LBI, 94% at SRI). The mouse lymphoma cell mutagenicity results are concordant with the rodent chronic assay results in 78% of 50 chemicals and with the Salmonella assay results in 79% of 56 chemicals. Fifteen carcinogens were examined for genotoxic effects in mouse lymphoma, Salmonella, Chinese hamster ovary (CHO) chromosomal aberration, and CHO sister chromatid exchange assay. Eight of these were positive in all four assays. Of the seven noncarcinogens that were tested in these four assays, none was negative in all four. The main conclusion to be drawn from this study is that the mouse lymphoma cell forward mutation assay, as performed and evaluated in this study, detects chemical mutagenicity in a manner that is highly consistent with other genetic endpoints as well as rodent carcinogenicity studies. Thus the assay quality control and response criteria established in this study led not only to a high degree of reproducibility but also to an apparently reliable detection of mutagenic activity.
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Affiliation(s)
- W J Caspary
- Cellular and Genetic Toxicology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
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Mitchell AD, Myhr BC, Rudd CJ, Caspary WJ, Dunkel VC. Evaluation of the L5178Y mouse lymphoma cell mutagenesis assay: methods used and chemicals evaluated. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 1988; 12 Suppl 13:1-18. [PMID: 3416837 DOI: 10.1002/em.2860120502] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A general protocol, modified from the one described by Clive and Spector (Mutat Res 31:17-29, 1975), was followed by two laboratories, Litton Bionetics, Inc., and SRI International, to evaluate 63 coded chemicals from 16 chemical classes for mutagenic activity at the thymidine kinase locus in L5178Y TK+/- 3.7.2C mouse lymphoma cells. The general protocol is discussed. Some procedural variations introduced by both laboratories are described and discussed in terms of their potential effect on the comparative results of the assay. Also included are the chemical structures, molecular weights, and functional classifications of the 63 chemicals. The assay appeared to tolerate the specific procedural variations in each laboratory without changing its reliability.
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Affiliation(s)
- A D Mitchell
- Department of Cellular and Genetic Toxicology, SRI International, Menlo Park, California
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Mitchell AD, Rudd CJ, Caspary WJ. Evaluation of the L5178Y mouse lymphoma cell mutagenesis assay: intralaboratory results for sixty-three coded chemicals tested at SRI International. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 1988; 12 Suppl 13:37-101. [PMID: 3416841 DOI: 10.1002/em.2860120504] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
SRI used the L5178Y mouse lymphoma cell forward mutation assay to determine the mutagenic activity of 63 coded chemicals from 16 chemical classes. Replicate experiments were performed to assess the reproducibility of the assay within the laboratory. The evaluations (positive or negative) of the first two repeat experiments with the chemicals were the same for 116 (87%) of 134 tests. Evaluational differences between the first two experiments were fewer in the presence of induced S9 (6 tests) than in the absence of S9 (12 tests). The most commonly observed variability was the magnitude of positive mutagenic responses; this may be attributed to factors such as compound solubilities, S9 activation conditions, and differential recovery of mutant cells. Some consistency was observed in the responses of compounds of various chemical classes. Generally, antibiotics (ABO) and the azo dyes, azoxy and hydrazo compounds, diazoalkanes, nitriles and azides (AZO), were mutagenic with S9; alkyl, acyl, and aryl halides, halogenated ethers, and halohydrins (HAL) were more strongly mutagenic with than without S9; and monofunctional polycyclic aromatic hydrocarbons and fluorenones (PAH) were mutagenic only with S9. Amine-1-oxides (AMO), alkyl and aryl epoxides (EPO), and nitroalkanes, nitroaromatics, nitroquinolines, nitrofurans, and nitroimidazoles (NIT) were mutagenic with and without S9; amides, sulfonamides, aromatic amines, aliphatic amines, hydroxylamines, and benzidine and its derivatives (AMI) were mutagenic without S9; and methyl carbamate (the only monofunctional carbamate) and thioureas (CBM) induced a negative response under both conditions.
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Affiliation(s)
- A D Mitchell
- Department of Cellular and Genetic Toxicology, SRI International, Menlo Park, California
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