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Pfuhler S, Downs TR, Hewitt NJ, Hoffmann S, Mun GC, Ouedraogo G, Roy S, Curren RD, Aardema MJ. Validation of the 3D reconstructed human skin micronucleus (RSMN) assay: an animal-free alternative for following-up positive results from standard in vitro genotoxicity assays. Mutagenesis 2021; 36:1-17. [PMID: 33544138 PMCID: PMC8081377 DOI: 10.1093/mutage/geaa035] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 11/25/2020] [Indexed: 11/13/2022] Open
Abstract
In vitro test batteries have become the standard approach to determine the genotoxic potential of substances of interest across industry sectors. While useful for hazard identification, standard in vitro genotoxicity assays in 2D cell cultures have limited capability to predict in vivo outcomes and may trigger unnecessary follow-up animal studies or the loss of promising substances where animal tests are prohibited or not desired. To address this problem, a team of regulatory, academia and industry scientists was established to develop and validate 3D in vitro human skin-based genotoxicity assays for use in testing substances with primarily topical exposure. Validation of the reconstructed human skin micronucleus (RSMN) assay in MatTek Epi-200™ skin models involved testing 43 coded chemicals selected by independent experts, in four US/European laboratories. The results were analysed by an independent statistician according to predefined criteria. The RSMN assay showed a reproducibly low background micronucleus frequency and exhibited sufficient capacity to metabolise pro-mutagens. The overall RSMN accuracy when compared to in vivo genotoxicity outcomes was 80%, with a sensitivity of 75% and a specificity of 84%, and the between- and within-laboratory reproducibility was 77 and 84%, respectively. A protocol involving a 72-h exposure showed increased sensitivity in detecting true positive chemicals compared to a 48-h exposure. An analysis of a test strategy using the RSMN assay as a follow-up test for substances positive in standard in vitro clastogenicity/aneugenicity assays and a reconstructed skin Comet assay for substances with positive results in standard gene mutation assays results in a sensitivity of 89%. Based on these results, the RSMN assay is considered sufficiently validated to establish it as a ‘tier 2’ assay for dermally exposed compounds and was recently accepted into the OECD’s test guideline development program.
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Affiliation(s)
| | | | | | | | - Greg C Mun
- Institute for In Vitro Sciences, Inc., Gaithersburg, MD, USA
| | | | | | - Rodger D Curren
- Institute for In Vitro Sciences, Inc., Gaithersburg, MD, USA
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Curren RD, Southee JA, Spielmann H, Liebsch M, Fentem JH, Balls M. The Role of Prevalidation in the Development, Validation and Acceptance of Alternative Methods. Altern Lab Anim 2020. [DOI: 10.1177/026119299502300206] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Experience has shown that the outcome of large and expensive validation studies on alternative methods can be compromised if their managers do not insist that optimised test protocols and proof of their performance are submitted before the start of the formal validation study. One way for the sponsors of validation studies to confirm both the likely relevance of a method for its stated purpose and its readiness for validation would be to require a prevalidation study before formal validation was contemplated. This process would involve the developers (or other proponents of the method) and selected independent laboratories in protocol refinement (Phase I) and protocol transfer (Phase II). The optimised protocol would then be assessed in a protocol performance phase (Phase III), which would involve the testing of a relevant set of coded test materials and an evaluation of a proposed prediction model. In certain circumstances, a successful outcome of Phase III might be sufficient for promotion of the regulatory acceptance of the method. Normally, however, the method would proceed to a formal validation study. The European Centre for the Validation of Alternative Methods, a recognised validation authority, now proposes to introduce this prevalidation scheme into its validation strategy.
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Affiliation(s)
- Rodger D. Curren
- Microbiological Associates, Inc., 9900 Blackwell Road, Rockville, MD 20850, USA
| | - Jacqueline A. Southee
- Microbiological Associates Ltd, Stirling University Innovation Park, Stirling FK9 4NF, UK
| | - Horst Spielmann
- ZEBET, Bundesinstitut für gesundheitlichen Verbraucherschutz und Veterinärmedizin (BgVV), Diedersdorfer Weg 1, D-12277 Berlin, Germany
| | - Manfred Liebsch
- ZEBET, Bundesinstitut für gesundheitlichen Verbraucherschutz und Veterinärmedizin (BgVV), Diedersdorfer Weg 1, D-12277 Berlin, Germany
| | | | - Michael Balls
- ECVAM, JRC Environment Institute, 21020 Ispra (Va), Italy
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Botham PA, Chamberlain M, Barratt MD, Curren RD, Esdaile DJ, Gardner JR, Gordon VC, Hildebrand B, Lewis RW, Liebsch M, Logemann P, Osborne R, Ponec M, Régnier JF, Steiling W, Walker AP, Balls M. A Prevalidation Study on In Vitro Skin Corrosivity Testing. Altern Lab Anim 2020. [DOI: 10.1177/026119299502300207] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Philip A. Botham
- ZENECA Central Toxicology Laboratory, Alderley Park, Macclesfield, Cheshire SK10 4TJ, UK
| | - Mark Chamberlain
- Environmental Safety Laboratory, Unilever Research, Colworth House, Sharnbrook, Bedford MK44 1LQ, UK
| | - Martin D. Barratt
- Environmental Safety Laboratory, Unilever Research, Colworth House, Sharnbrook, Bedford MK44 1LQ, UK
| | - Rodger D. Curren
- Microbiological Associates Inc., 9900 Blackwell Road, Rockville, MD 20878, USA
| | - David J. Esdaile
- Rhône-Poulenc Secteur Agro, 355 Rue Dostoievski, BP 153, 06903 Sophia Antipolis Cedex, France
| | - John R. Gardner
- Hazleton Europe, Otley Road, Harrogate, N. Yorkshire HG3 1PY, UK
| | | | | | - Richard W. Lewis
- ZENECA Central Toxicology Laboratory, Alderley Park, Macclesfield, Cheshire SK10 4TJ, UK
| | - Manfred Liebsch
- ZEBET, Bundesinstitut für gesundheitlichen Verbraucherschutz und Veterinärmedizin (BgVV), Diedersdorfer Weg 1, D-12277 Berlin, Germany
| | - Pamela Logemann
- Tissue Sciences, 10933 North Torrey Pines Road, La Jolla, CA 92037-1005, USA
| | - Rosemarie Osborne
- The Procter & Gamble Company, Miami Valley Laboratories, P.O. Box 538707, Cincinnati, OH 45253-8707, USA
| | - Maria Ponec
- Department of Dermatology, University Hospital Leiden, P.O. Box 9600, 2300 RC Leiden, The Netherlands
| | | | | | - Arthur P. Walker
- Apojay Consultancy, 6 Cragside, Whitley Bay, Tyne & Wear NE26 3DU, UK
| | - Michael Balls
- ECVAM, JRC Environment Institute, 21020 Ispra (Va), Italy
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4
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Worth AP, Fentem JH, Balls M, Botham PA, Curren RD, Earl LK, Esdaile DJ, Liebsch M. An Evaluation of the Proposed OECD Testing Strategy for Skin Corrosion. Altern Lab Anim 2020. [DOI: 10.1177/026119299802600512] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The use of testing strategies which incorporate a range of alternative methods and which use animals only as a last resort is widely considered to provide a reliable way of predicting chemical toxicity while minimising animal testing. The widespread concern over the severity of the Draize rabbit test for assessing skin irritation and corrosion led to the proposal of a stepwise testing strategy at an OECD workshop in January 1996. Subsequently, the proposed testing strategy was adopted, with minor modifications, by the OECD Advisory Group on Harmonization of Classification and Labelling. This article reports an evaluation of the proposed OECD testing strategy as it relates to the classification of skin corrosives. By using a set of 60 chemicals, an assessment was made of the effect of applying three steps in the strategy, taken both individually and in sequence. The results indicate that chemicals can be classified as corrosive (C) or non-corrosive (NC) with sufficient reliability by the sequential application of three alternative methods, i.e., structure-activity relationships (where available), pH measurements, and a single in vitro method (either the rat skin transcutaneous electrical resistance (TER) assay or the EPISKIN™ assay). It is concluded that the proposed OECD strategy for skin corrosion can be simplified without compromising its predictivity. For example, it does not appear necessary to measure acid/alkali reserve (buffering capacity) in addition to pH for the classification of pure chemicals.
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Affiliation(s)
| | | | - Michael Balls
- ECVAM, JRC Environment Institute, 21020 Ispra (VA), Italy
| | - Philip A. Botham
- Central Toxicology Laboratory, ZENECA, Alderley Park, Macclesfield, Cheshire SK10 4TJ, UK
| | - Rodger D. Curren
- Institute for In Vitro Sciences, 21 Firstfield Road, Gaithersburg, MD 20878, USA
| | - Lesley K. Earl
- SEAC Toxicology Unit, Unilever Research, Colworth House, Sharnbrook, Bedfordshire MK44 1LQ, UK
| | - David J. Esdaile
- Rhône-Poulenc Agro, 355 rue Dostoievski, 06903 Sophia Antipolis Cedex, France
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5
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Archer G, Balls M, Bruner LH, Curren RD, Fentem JH, Holzhütter HG, Liebsch M, Lovell DP, Southee JA. The Validation of Toxicological Prediction Models. Altern Lab Anim 2020. [DOI: 10.1177/026119299702500507] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
An alternative method is shown to consist of two parts: the test system itself; and a prediction model for converting in vitro endpoints into predictions of in vivo toxicity. For the alternative method to be relevant and reliable, it is important that its prediction model component is of high predictive power and is sufficiently robust against sources of data variability. In other words, the prediction model must be subjected to criticism, leading successful models to the state of confirmation. It is shown that there are certain circumstances in which a new prediction model may be introduced without the necessity to generate new test system data.
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Affiliation(s)
- Graeme Archer
- ECVAM, JRC Environment Institute, 21020 Ispra (VA), Italy
| | - Michael Balls
- ECVAM, JRC Environment Institute, 21020 Ispra (VA), Italy
| | - Leon H. Bruner
- The Procter & Gamble Company, Health and Beauty Care Europe, Egham, Surrey TW20 9NW, UK
| | - Rodger D. Curren
- Institute for In Vitro Sciences Inc., Suite 220, 21 Firstfield Road, Gaithersburg, MD 20878, USA
| | | | - Hermann-Georg Holzhütter
- Humboldt-Universität zu Berlin, Bereich Medizin (Charité), Institut für Biochemie, Mon Bijou Strasse 2a, 10117 Berlin, Germany
| | - Manfred Liebsch
- ZEBET, Bundesinstitut für gesundheitlichen Verbraucherschutz und Veterinärmedizin (BgVV), Diedersdorfer Weg 1, 12277 Berlin, Germany
| | - David P. Lovell
- BIBRA International, Woodmansterne Road, Carshalton, Surrey SM5 4DS, UK
| | - Jacqueline A. Southee
- Microbiological Associates Ltd, Stirling University Innovation Park, Stirling FK9 4NF, UK
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Fowle J“JR, Curren RD, Hartung T, Proctor C, Wilcox N. Twenty-First Century In Vitro Toxicology Testing Methods and the Assessment of e-Cigarettes. ACTA ACUST UNITED AC 2017. [DOI: 10.1089/aivt.2017.29011.rtl] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
| | | | - Thomas Hartung
- Evidence-Based Toxicology, Doerenkamp-Zbinden, Department of Environmental Health and Engineering, Center for Alternatives to Animal Testing, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Christopher Proctor
- Scientific Product Stewardship, British American Tobacco, Southampton, United Kingdom
| | - Neil Wilcox
- Low Country Consulting, Bluffton, South Carolina
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7
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Sauer UG, Hill EH, Curren RD, Raabe HA, Kolle SN, Teubner W, Mehling A, Landsiedel R. Local tolerance testing under REACH: Accepted non-animal methods are not on equal footing with animal tests. Altern Lab Anim 2017; 44:281-99. [PMID: 27494627 DOI: 10.1177/026119291604400311] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In general, no single non-animal method can cover the complexity of any given animal test. Therefore, fixed sets of in vitro (and in chemico) methods have been combined into testing strategies for skin and eye irritation and skin sensitisation testing, with pre-defined prediction models for substance classification. Many of these methods have been adopted as OECD test guidelines. Various testing strategies have been successfully validated in extensive in-house and inter-laboratory studies, but they have not yet received formal acceptance for substance classification. Therefore, under the European REACH Regulation, data from testing strategies can, in general, only be used in so-called weight-of-evidence approaches. While animal testing data generated under the specific REACH information requirements are per se sufficient, the sufficiency of weight-of-evidence approaches can be questioned under the REACH system, and further animal testing can be required. This constitutes an imbalance between the regulatory acceptance of data from approved non-animal methods and animal tests that is not justified on scientific grounds. To ensure that testing strategies for local tolerance testing truly serve to replace animal testing for the REACH registration 2018 deadline (when the majority of existing chemicals have to be registered), clarity on their regulatory acceptance as complete replacements is urgently required.
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Affiliation(s)
- Ursula G Sauer
- Scientific Consultancy - Animal Welfare, Neubiberg, Germany
| | - Erin H Hill
- Institute for In Vitro Sciences (IIVS), Gaithersburg, MD, USA
| | - Rodger D Curren
- Institute for In Vitro Sciences (IIVS), Gaithersburg, MD, USA
| | - Hans A Raabe
- Institute for In Vitro Sciences (IIVS), Gaithersburg, MD, USA
| | - Susanne N Kolle
- BASF SE, Experimental Toxicology and Ecology, Ludwigshafen, Germany
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8
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Mun GC, Aardema MJ, Hu T, Barnett B, Kaluzhny Y, Klausner M, Karetsky V, Dahl EL, Curren RD. Further development of the EpiDerm™ 3D reconstructed human skin micronucleus (RSMN) assay. Mutation Research/Genetic Toxicology and Environmental Mutagenesis 2009; 673:92-9. [DOI: 10.1016/j.mrgentox.2008.12.004] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Revised: 12/12/2008] [Accepted: 12/22/2008] [Indexed: 10/21/2022]
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9
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Becker RA, Borgert CJ, Webb S, Ansell J, Amundson S, Portier CJ, Goldberg A, Bruner LH, Rowan A, Curren RD, Stott WT. Report of an ISRTP Workshop: Progress and barriers to incorporating alternative toxicological methods in the U.S. Regul Toxicol Pharmacol 2006; 46:18-22. [PMID: 16876299 DOI: 10.1016/j.yrtph.2006.06.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2006] [Indexed: 11/26/2022]
Abstract
The workshop objectives were to explore progress in implementing new, revised and alternative toxicological test methods across regulatory evaluation frameworks and decision-making programs in the United States, to identify barriers and to develop recommendations to further promote adoption of approaches that reduce, refine, or replace the use of animal methods. The workshop included sessions on: (1) current research, development, and validation of alternative methods within the U.S. federal government; (2) emerging alternative methodologies with potential applications to a broad spectrum of toxicity evaluation strategies; (3) tiered evaluation ("intelligent testing") strategies; and (4) identification of, and recommendations to address, critical barriers that affect adoption and use of new, revised alternative toxicological test methods by U.S. regulatory agencies. Through facilitated discussion, a list of barriers and recommendations were developed and grouped into categories of economic/financial, scientific/technical, and regulatory/policy. Overall, participants from all sectors collectively supported catalyzing actions to promote more meaningful and rapid progress for research to develop alternative methods focused for use in regulatory programs, accelerated lab investigations to validate such alternative methods and adoption of regulatory frameworks which embrace and incorporate these validated alternatives.
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Curren RD, Mun GC, Gibson DP, Aardema MJ. Development of a method for assessing micronucleus induction in a 3D human skin model (EpiDerm™). Mutation Research/Genetic Toxicology and Environmental Mutagenesis 2006; 607:192-204. [PMID: 16781186 DOI: 10.1016/j.mrgentox.2006.04.016] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2005] [Revised: 03/28/2006] [Accepted: 04/12/2006] [Indexed: 11/27/2022]
Abstract
To meet the requirements of the EU 7th Amendment to the Cosmetics Directive, manufacturers of cosmetics products will need to ascertain the safety of ingredients using non-animal methods. Starting in 2009, in vivo genotoxicity tests for cosmetics ingredients will not be allowed. Skin is a target area of interest for many cosmetic products because of its relatively high exposure. Therefore, it would be beneficial to have a non-animal, skin-based genotoxicity assay, especially one that utilized human skin in vitro. In this paper, we describe the development of a reproducible micronucleus assay that uses EpiDerm engineered human skin constructs (MatTek Corp., Ashland, MA). We describe methods for isolating single cells from the 3D skin model and for processing the cells for microscopic analysis of micronuclei (MN). In addition, since little was known about the kinetics of the dividing keratinocytes in the EpiDerm model, we evaluated whether cytochalasin B (Cyt-B) could be used to distinguish the population of dividing cells allowing the development of a micronucleus assay in binucleated cells. We found that the frequency of binucleated cells increased both with time and with increasing concentration of Cyt-B. After a 48-h exposure, 30-50% binucleated cells were reproducibly obtained. Finally, we evaluated micronucleus induction using the model genotoxicants mitomycin C (MMC) and vinblastine sulfate (VB). The background frequency of MN is very low and reproducible in this model, and statistically significant increases in the frequency of micronucleated cells were induced by both MMC and VB. These are initial steps in developing a routine "in vivo-like" assay for chromosomal damage in human tissue. It is hoped that other investigators utilize these methods to further the understanding of this potentially valuable new non-animal method.
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Affiliation(s)
- Rodger D Curren
- Institute for In Vitro Sciences Inc., 21 Firstfield Road, Suite 220, Gaithersburg, MD 20878, USA.
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11
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Chhabra RS, Ress NB, Harbell JW, Curren RD. Evaluation of Some In Vitro Tests to Reduce and Replace the Sub-acute Animal Toxicity Studies. Altern Lab Anim 2004; 32 Suppl 1A:137-40. [DOI: 10.1177/026119290403201s21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The toxicologic and carcinogenic potential of chemicals is usually determined through a sequence of acute, sub-acute (14-day), sub-chronic (90-day) and chronic (two-year) studies in rats and mice of both sexes. The US National Toxicology Program (NTP) does not conduct acute toxicity studies. Dose levels for 14-day toxicity studies are typically estimated from information in the literature, if available. The toxicology information obtained from 14-day studies is used in the selection of doses for 90-day studies. The protocol for 14-day studies consists of five doses and control groups and five animals per group of each sex and species, resulting in the use of 120 animals per study. At present, in addition to refining the current testing protocols, the NTP is evaluating the potential for in vitro test methods to partially or completely avoid the need for 14-day toxicity studies, especially for chemicals where the dermal route of exposure is used. The in vitro assays used were the EpiDerm™ bioassay to estimate dermal irritation, the neutral red uptake (NRU) bioassay to estimate systemic toxicity and the primary rat hepatocyte cytotoxicity (PRHC) assay to estimate hepatotoxicity. The purpose of using these assays was to assess their potential for predicting relative in vivo toxicity and to support dose selection decisions for 90-day studies. In general, based on these limited number of studies, the EpiDerm and NRU tests were predictive of the responses observed in in vivo studies. However, a larger comparative database is needed to derive definitive conclusions regarding the value of in vitro tests in the prediction of in vivo effects.
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Abstract
Ocular irritation testing has been one of the animal test methods most criticised by animal welfare advocates. Additional criticism has arisen from within the scientific community, based on the variability of the animal test results and the questionable relevance of the extremely high dose levels employed. As a result, the Draize eye irritation test has been one of the main targets for in vitro replacement. Despite extensive efforts, however, there is still no in vitro method that is fully validated as a regulatory replacement. In spite of this, many individual companies are using diverse in vitro ocular irritation tests to gain important safety and efficacy information about their products and raw materials, eliminating the need for animal testing in the process. This is done in a safe fashion by applying intelligent testing paradigms. ECVAM has played a major role in this success, through its many programmes that have emphasised the importance of understanding the true toxicological need, and then using in vitro tests to provide that information. Thus, even in the absence of a successfully validated regulatory assay, the desired result of reducing animal testing is being met.
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Affiliation(s)
- Rodger D Curren
- Institute for In Vitro Sciences, Inc., Suite 220, 21 Firstfield Road, Gaithersburg, MD 20878, USA
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Bruner LH, Carr GJ, Harbell JW, Curren RD. An investigation of new toxicity test method performance in validation studies: 1. Toxicity test methods that have predictive capacity no greater than chance. Hum Exp Toxicol 2002; 21:305-12. [PMID: 12195934 DOI: 10.1191/0960327102ht252oa] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
An approach commonly used to measure new toxicity test method (NTM) performance in validation studies is to divide toxicity results into positive and negative classifications, and the identify true positive (TP), true negative (TN), false positive (FP) and false negative (FN) results. After this step is completed, the contingent probability statistics (CPS), sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) are calculated. Although these statistics are widely used and often the only statistics used to assess the performance of toxicity test methods, there is little specific guidance in the validation literature on what values for these statistics indicate adequate performance. The purpose of this study was to begin developing data-based answers to this question by characterizing the CPS obtained from an NTM whose data have a completely random association with a reference test method (RTM). Determining the CPS of this worst-case scenario is useful because it provides a lower baseline from which the performance of an NTM can be judged in future validation studies. It also provides an indication of relationships in the CPS that help identify random or near-random relationships in the data. The results from this study of randomly associated tests show that the values obtained for the statistics vary significantly depending on the cut-offs chosen, that high values can be obtained for individual statistics, and that the different measures cannot be considered independently when evaluating the performance of an NTM. When the association between results of an NTM and RTM is random the sum of the complementary pairs of statistics (sensitivity + specificity, NPV + PPV) is approximately 1, and the prevalence (i.e., the proportion of toxic chemicals in the population of chemicals) and PPV are equal. Given that combinations of high sensitivity-low specificity or low specificity-high sensitivity (i.e., the sum of the sensitivity and specificity equal to approximately 1) indicate lack of predictive capacity, an NTM having these performance characteristics should be considered no better for predicting toxicity than by chance alone.
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Affiliation(s)
- L H Bruner
- Gillette Company, Gillette Environment, Health & Safety, Needham, Massachusetts 02492, USA.
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Bruner LH, Carr GJ, Harbell JW, Curren RD. An investigation of new toxicity test method performance in validation studies: 3. Sensitivity and specificity are not independent of prevalence or distribution of toxicity. Hum Exp Toxicol 2002; 21:325-34. [PMID: 12195936 DOI: 10.1191/0960327102ht254oa] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Often, the only measures of toxicity test performance provided in validation studies are the contingent probability statistics (CPS) sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Sensitivity and specificity are generally used in preference to NPV and PPV since NPV and PPV are assumed to vary with changes in prevalence while sensitivity and specificity are assumed to be independent of changes in prevalence. The purpose of the studies reported here was to test whether or not sensitivity and specificity are actually independent of changes in prevalence. Results derived from these studies indicate that sensitivity and specificity vary significantly depending on the prevalence of toxic substances in the set of chemicals being tested. This means sensitivity and specificity should not always be considered constant indicators of toxicity test performance.
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Affiliation(s)
- L H Bruner
- Gillette Environment, Health & Safety, Needham, Massachusetts, USA.
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Bruner LH, Carr GJ, Harbell JW, Curren RD. An investigation of new toxicity test method performance in validation studies: 2. Comparison of three measures of toxicity test performance. Hum Exp Toxicol 2002; 21:313-23. [PMID: 12195935 DOI: 10.1191/0960327102ht253oa] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
An area that requires further research is how best to measure test method performance in validation studies and how to set criteria that should be used to judge the adequacy of this performance. The studies reported here were designed to begin an investigation of these questions. Computer simulations were used to generate data sets similar to those that might be obtained from a large validation study. These data were then analysed using three procedures including determination of the 95% prediction interval (PI), calculation of Pearson's correlation coefficient and calculation of the contingent probability statistics (CPS), sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). The results of this work suggest that of the three approaches examined, quantitative measurements with calculation of the 95% PI provide the most information to allow discrimination between the performance of several different NTMs. The results also suggest that dividing data sets into positive and negative toxicity classifications followed by the calculation of CPS leads to considerable information loss. This loss of information may be so significant that it is not possible in certain circumstances to distinguish between NTMs that are adequate and those that are not.
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Affiliation(s)
- L H Bruner
- Gillette Company, Gillette Environment, Health & Safety, Needham, Massachusetts 02914, USA.
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16
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Zuang V, Balls M, Botham PA, Coquette A, Corsini E, Curren RD, Elliott GR, Fentem JH, Heylings JR, Liebsch M, Medina J, Roguet R, van de Sandt JJM, Wiemann C, Worth AP. Follow-up to the ECVAM prevalidation study on in vitro tests for acute skin irritation. The European Centre for the Validation of Alternative Methods Skin Irritation Task Force report 2. Altern Lab Anim 2002; 30:109-29. [PMID: 11827575 DOI: 10.1177/026119290203000110] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The European Centre for the Validation of Alternative Methods (ECVAM) Skin Irritation Task Force was established in 1996, to review the status of the development and validation of alternative tests for skin irritation and corrosion, and to identify appropriate non-animal tests for predicting human skin irritation that were sufficiently well-developed to be prevalidated and validated by ECVAM. The EpiDerm method, based on a reconstituted human skin model, was proposed as being sufficiently well advanced to enter a prevalidation (PV) study. Based on a review of test protocols, prediction models (PMs), and data submitted by test developers on ten specified chemicals, with 20% sodium lauryl sulphate as a reference standard, the task force recommended the inclusion of four other tests: EPISKIN and PREDISKIN, based on reconstituted human epidermis or on human skin; the non-perfused pig-ear test, based on pig skin; and the skin integrity function test (SIFT), with ex vivo mouse skin. The prevalidation study on these methods was funded by ECVAM, and took place during 1999-2000. The outcome of the PV study was that none of the methods was ready to enter a formal validation study, and that the protocols and PMs of the methods had to be improved in order to increase their predictive abilities. Improved protocols and PMs for the EpiDerm and EPISKIN methods, the pig ear test, and the SIFT were presented at an extended Task Force meeting held in May 2001. It was agreed that, in the short term, the performance of the revised and harmonised EpiDerm and EPISKIN methods, as well as the modified SIFT, should be evaluated in a further study with a new set of 20 test chemicals. In addition, it was decided that the SIFT and the pig ear test would be compared to see if common endpoints (transepidermal water loss, methyl green-pyronine stain) could be identified.
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Affiliation(s)
- Valérie Zuang
- ECVAM, Institute for Health & Consumer Protection, European Commission Joint Research Centre, 21020 Ispra (VA), Italy
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17
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MacGregor JT, Collins JM, Sugiyama Y, Tyson CA, Dean J, Smith L, Andersen M, Curren RD, Houston JB, Kadlubar FF, Kedderis GL, Krishnan K, Li AP, Parchment RE, Thummel K, Tomaszewski JE, Ulrich R, Vickers AE, Wrighton SA. In vitro human tissue models in risk assessment: report of a consensus-building workshop. Toxicol Sci 2001; 59:17-36. [PMID: 11134541 DOI: 10.1093/toxsci/59.1.17] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Advances in the technology of human cell and tissue culture and the increasing availability of human tissue for laboratory studies have led to the increased use of in vitro human tissue models in toxicology and pharmacodynamics studies and in quantitative modeling of metabolism, pharmacokinetic behavior, and transport. In recognition of the potential importance of such models in toxicological risk assessment, the Society of Toxicology sponsored a workshop to evaluate the current status of human cell and tissue models and to develop consensus recommendations on the use of such models to improve the scientific basis of risk assessment. This report summarizes the evaluation by invited experts and workshop attendees of the current status of such models for prediction of human metabolism and identification of drug-drug interactions, prediction of human toxicities, and quantitative modeling of pharmacokinetic and pharmaco-toxicodynamic behavior. Consensus recommendations for the application and improvement of current models are presented.
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Affiliation(s)
- J T MacGregor
- Center for Drug Evaluation and Research, Food and Drug Administration, Rockville, Maryland 20857, USA.
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18
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Balls M, Berg N, Bruner LH, Curren RD, de Silva O, Earl LK, Esdaile DJ, Fentem JH, Liebsch M, Ohno Y, Prinsen MK, Spielmann H, Worth AP. Eye Irritation Testing: The Way Forward. The Report and Recommendations of ECVAM Workshop 34. Altern Lab Anim 1999; 27:53-77. [PMID: 25423402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
This is the report of the thirty-fourth of a series of workshops organised by the European Centre for the Validation of Alternative Methods (ECVAM). ECVAM's main goal, as defined in 1993 by its Scientific Advisory Committee, is to promote the scientific and regulatory acceptance of alternative methods which are of importance to the biosciences and which reduce, refine or replace the use of laboratory animals. One of the first priorities set by ECVAM was the implementation of procedures which would enable it to become well-informed about the state-of-the-art of non-animal test development and validation, and the potential for the possible incorporation of alternative tests into regulatory procedures. It was decided that this would be best achieved by the organisation of ECVAM workshops on specific topics, at which small groups of invited experts would review the current status of various types of in vitro tests and their potential uses, and make recommendations about the best ways forward (1). The workshop on Eye Irritation Testing: The Way Forward was held in Egham, UK, on 15-17 June 1998, under the chairmanship of Michael Balls (ECVAM, Italy). The workshop had two aims, the first of which was to review some of the previous multi-laboratory validation studies on alternatives to the Draize eye test and assess why many promising alternative methods were not successful in these studies. The second aim was to discuss strategies for making progress toward the short-term reduction, refinement, and eventual replacement, of the Draize test, including: a new approach to the validation of in vitro tests for eye irritancy, based on the use of reference standards, which promises to overcome some of the problems encountered in previous studies; the use of stepwise testing strategies which reduce and refine the use of animals in eye irritation testing; the use of multivariate and other statistical techniques for the further analysis of data generated in previous validation studies; and a programme of research aimed at understanding the underlying mechanisms of eye irritation.
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Affiliation(s)
- M Balls
- ECVAM, JRC Environment Institute, 21020 Ispra, Italy
| | - N Berg
- Novo Nordisk, Novo Alle, 2880 Bagsvaerd, Denmark
| | - L H Bruner
- Procter & Gamble (Health and Beauty Care), Lovett House, Lovett Road, Staines, Middlesex TW18 3AZ, UK
| | - R D Curren
- Institute for In Vitro Sciences, 21 Firstfield Road, Gaithersburg, MD 20878, USA
| | - O de Silva
- L'Oréal Recherche Avancée - Sciences du Vivant, 1 Avenue Eugène Schueller, 93601 Aulnay-sous-Bois Cedex, France
| | - L K Earl
- SEAC Toxicology Unit, Unilever Research, Colworth House, Sharnbrook, Bedford MK44 1LQ, UK
| | - D J Esdaile
- Rhône-Poulenc, 355 rue Dostoievski, 06903 Sophia Antipolis Cedex, France
| | - J H Fentem
- ECVAM, JRC Environment Institute, 21020 Ispra, Italy
| | - M Liebsch
- ZEBET, BgVV, Diedersdorfer Weg 1, 12277 Berlin, Germany
| | - Y Ohno
- Division of Pharmacology, Biological Safety Research Centre, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setakaya-ku, Tokyo 158, Japan
| | - M K Prinsen
- TNO Nutrition and Food Research Institute, Division of Toxicology, 3700 AJ Zeist, The Netherlands
| | - H Spielmann
- ZEBET, BgVV, Diedersdorfer Weg 1, 12277 Berlin, Germany
| | - A P Worth
- ECVAM, JRC Environment Institute, 21020 Ispra, Italy
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Worth AP, Fentem JH, Balls M, Botham PA, Curren RD, Earl LK, Esdaile DJ. An evaluation of the proposed OECD testing strategy for skin corrosion. Altern Lab Anim 1998; 26:709-720. [PMID: 26042494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The use of testing strategies which incorporate a range of alternative methods and which use animals only as a last resort is widely considered to provide a reliable way of predicting chemical toxicity while minimising animal testing. The widespread concern over the severity of the Draize rabbit test for assessing skin irritation and corrosion led to the proposal of a stepwise testing strategy at an OECD workshop in January 1996. Subsequently, the proposed testing strategy was adopted, with minor modifications, by the OECD Advisory Group on Harmonization of Classification and Labelling. This article reports an evaluation of the proposed OECD testing strategy as it relates to the classification of skin corrosives. By using a set of 60 chemicals, an assessment was made of the effect of applying three steps in the strategy, taken both individually and in sequence. The results indicate that chemicals can be classified as corrosive (C) or non-corrosive (NC) with sufficient reliability by the sequential application of three alternative methods, i.e., structure-activity relationships (where available), pH measurements, and a single in vitro method (either the rat skin transcutaneous electrical resistance (TER) assay or the EPISKIN™ assay). It is concluded that the proposed OECD strategy for skin corrosion can be simplified without compromising its predictivity. For example, it does not appear necessary to measure acid/alkali reserve (buffering capacity) in addition to pH for the classification of pure chemicals.
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Affiliation(s)
- A P Worth
- ECVAM, JRC Environment Institute, Ispra, Italy
| | - J H Fentem
- ECVAM, JRC Environment Institute, Ispra, Italy
| | - M Balls
- ECVAM, JRC Environment Institute, Ispra, Italy
| | - P A Botham
- Central Toxicology Laboratory, ZENECA, Alderley Park, Macclesfield, UK
| | - R D Curren
- Institute for In Vitro Sciences, Gaithersburg, MD, USA
| | - L K Earl
- SEAC Toxicology Unit, Unilever Research, Sharnbrook, UK
| | - D J Esdaile
- Rhône-Poulenc Agro, Sophia Antipolis Cedex, France
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20
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Abstract
The necessity of using animals to test whether new chemicals and products are eye irritants has been questioned with increasing frequency and fervor over the last 20 years. During this time many new nonanimal methods have been proposed as reliable alternatives to the traditional rabbit (Draize) test. To date, however, none of these nonanimal (in vitro) tests have become universally accepted as a complete replacement for the Draize test. To understand why a complete replacement has not been found, one has to first understand the reasonably complex structure of the eye, the standard Draize scoring scale--which is based on a qualitative evaluation of three different tissues--the differences between human and rabbit eyes, the intrinsic variability of the animal test, and the details of the different in vitro tests that have been proposed as replacements. The in vitro tests vary from relatively simple assays using single cells to more sophisticated assays that use discarded animal tissue or artificially constructed human tissue. It is clear that appropriately designed in vitro tests will eventually give more useful mechanistic information about ocular injury from which we can more comfortably predict the risk of human eye irritation from new products and ingredients.
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Affiliation(s)
- R D Curren
- Institute for In Vitro Sciences, Inc., Gaithersburg, Maryland, USA.
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21
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Abstract
Before nonanimal toxicity tests may be officially accepted by regulatory agencies, it is generally agreed that the validity of the new methods must be demonstrated in an independent, scientifically sound validation program. Validation has been defined as the demonstration of the reliability and relevance of a test method for a particular purpose. This paper provides a brief review of the development of the theoretical aspects of the validation process and updates current thinking about objectively testing the performance of an alternative method in a validation study. Validation of alternative methods for eye irritation testing is a specific example illustrating important concepts. Although discussion focuses on the validation of alternative methods intended to replace current in vivo toxicity tests, the procedures can be used to assess the performance of alternative methods intended for other uses.
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Affiliation(s)
- L H Bruner
- Procter & Gamble Company, Health and Beauty Care Europe, Staines, Middlesex, United Kingdom.
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22
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Abstract
As part of the Interagency Regulatory Alternatives Group (IRAG) program to evaluate the state of the art in the development of alternative (non-whole animal) eye irritation tests, academic and industrial organizations were invited to submit in vitro eye irritation data generated in their laboratories to one of several working groups for review. The assays reviewed in this report (from Working Group 5. "Other Assays") were the EYTEX assay, tissue equivalent assay, a cytotoxicity assay using three-dimensional human fibroblast constructs, the Microtox assay, and other miscellaneous assays. Each submission consisted of raw data for chemicals and products tested, a description of the methodology, and an analysis (generally by regression analysis and Pearson's correlation coefficient) for the performance of the in vitro test relative to its ability to predict individual ocular tissue scores or total ocular score. In vivo data were generated according to the scoring methods proposed by Draize. Working Group 5 evaluated the submissions and commented on the utility of the assays. The variability of the in vivo data made conclusions difficult in many situations. Most of these assays were deemed useful (within limited chemical classes) for screening purposes or for use in conjunction with other toxicological information.
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Affiliation(s)
- R D Curren
- Microbiological Associates, Inc., Rockville, MD, USA
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23
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Gettings SD, Lordo RA, Hintze KL, Bagley DM, Casterton PL, Chudkowski M, Curren RD, Demetrulias JL, Dipasquale LC, Earl LK, Feder PI, Galli CL, Glaza SM, Gordon VC, Janus J, Kurtz PJ, Marenus KD, Moral J, Pape WJ, Renskers KJ, Rheins LA, Roddy MT, Rozen MG, Tedeschi JP, Zyracki J. The CTFA Evaluation of Alternatives Program: an evaluation of in vitro alternatives to the Draize primary eye irritation test. (Phase III) surfactant-based formulations. Food Chem Toxicol 1996; 34:79-117. [PMID: 8603801 DOI: 10.1016/0278-6915(96)89525-1] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The CTFA Evaluation of Alternatives Program is an evaluation of the relationship between data from the Draize primary eye irritation test and comparable data from a selection of promising in vitro eye irritation tests. In Phase III, data from the Draize test and 41 in vitro endpoints on 25 representative surfactant-based personal care formulations were compared. As in Phase I and Phase II, regression modelling of the relationship between maximum average Draize score (MAS) and in vitro endpoint was the primary approach adopted for evaluating in vitro assay performance. The degree of confidence in prediction of MAS for a given in vitro endpoint is quantified in terms of the relative widths of prediction intervals constructed about the fitted regression curve. Prediction intervals reflect not only the error attributed to the model but also the material-specific components of variation in both the Draize and the in vitro assays. Among the in vitro assays selected for regression modeling in Phase III, the relationship between MAS and in vitro score was relatively well defined. The prediction bounds on MAS were most narrow for materials at the lower or upper end of the effective irritation range (MAS = 0-45), where variability in MAS was smallest. This, the confidence with which the MAS of surfactant-based formulations is predicted is greatest when MAS approaches zero or when MAS approaches 45 (no comment is made on prediction of MAS > 45 since extrapolation beyond the range of observed data is not possible). No single in vitro endpoint was found to exhibit relative superiority with regard to prediction of MAS. Variability associated with Draize test outcome (e.g. in MAS values) must be considered in any future comparisons of in vivo and in vitro test results if the purpose is to predict in vivo response using in vitro data.
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Affiliation(s)
- S D Gettings
- Cosmetic, Toiletry and Fragrance Association, Washington, DC 20036, USA
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24
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Sina JF, Galer DM, Sussman RG, Gautheron PD, Sargent EV, Leong B, Shah PV, Curren RD, Miller K. A collaborative evaluation of seven alternatives to the Draize eye irritation test using pharmaceutical intermediates. Fundam Appl Toxicol 1995; 26:20-31. [PMID: 7657059 DOI: 10.1006/faat.1995.1071] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Much of the data which have been generated on in vitro alternatives to the Draize eye irritation test have dealt with compounds within a specific chemical class or product category. However, in the pharmaceutical industry, it is often necessary to evaluate materials which are not related in structure or properties. It was thus decided to evaluate a diverse series of chemicals in seven in vitro methods for estimating ocular irritation. Thirty-seven test materials were chosen to represent a broad range of pH, solubility, and in vivo irritation potential. Assays were chosen to include as many different types of end points as practical. The group of assays was composed of TOPKAT (assessing structure-activity relationships), bovine corneal opacity-permeability (BCO-P; corneal opacity/toxicity), Eytex (protein coagulation), neutral red uptake (cytotoxicity), MTT in living dermal equivalent (cytotoxicity), Microtox (cytotoxicity in bacteria), and CAMVA (inflammation/toxicity). The results of the study indicated that, in general, the cytotoxicity end points did not correlate well with the in vivo data. The BCO-P, CAMVA, and Eytex assays had the best overall concordance (88.9, 75.8, and 75.0%, respectively) with this set of compounds. Estimation of irritation potential based on structure-activity (TOPKAT) was possible for only approximately 50% of the compounds; however, the assay showed 100% sensitivity (i.e., no false negatives), but low specificity (i.e., negatives correctly identified only 54.5% of the time). These data suggest that for screening of chemicals of diverse structure and properties, the more mechanism-based assays, as opposed to general cytotoxicity assays, hold more promise and should be further evaluated.
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Affiliation(s)
- J F Sina
- Merck Research Laboratories, West Point, Pennsylvania 19486, USA
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25
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Gettings SD, Dipasquale LC, Bagley DM, Casterton PL, Chudkowski M, Curren RD, Demetrulias JL, Feder PI, Galli CL, Gay R. The CTFA Evaluation of Alternatives Program: an evaluation of in vitro alternatives to the Draize primary eye irritation test. (Phase II) oil/water emulsions. Food Chem Toxicol 1994; 32:943-76. [PMID: 7959449 DOI: 10.1016/0278-6915(94)90092-2] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The Cosmetic, Toiletry and Fragrance Association (CTFA) Evaluation of Alternatives Program is an evaluation of the relationship between Draize ocular safety test data and comparable data from a selection of in vitro tests. In Phase II, 18 representative oil/water-based personal-care formulations were subjected to the Draize primary eye safety test and 30 in vitro assay protocols (14 different types of in vitro endpoints were evaluated; the remainder were protocol variations). Correlation of in vitro with in vivo data was evaluated using analysis of sensitivity/specificity and statistical analysis of the relationship between maximum average Draize score (MAS) and in vitro endpoint. Regression modelling is the primary approach adopted in the CTFA Program for evaluating in vitro assay performance. The objective of regression analysis is to predict MAS for a given test material (and to place upper and lower prediction interval bounds on the range in which the MAS is anticipated to fall with high probability) conditional on observing an in vitro assay score for that material. The degree of confidence in prediction is quantified in terms of the relative widths of prediction intervals constructed about the fitted regression curves: the narrower the prediction interval, the more predictive of the Draize score is the in vitro test result. 16 assays were shown to have the greatest agreement with the Draize procedure and were therefore selected for regression analysis. Based on the magnitude of the 95% prediction bounds of each of the 16 selected assays over the range of test data, it may be inferred that prediction of MAS values from experimentally determined in vitro scores is more accurate for oil/water-based formulations with lower rather than higher irritancy potential. The assays selected for modelling in Phase II generally exhibited weaker relationships with MAS than those selected in Phase I (evaluated using hydroalcoholic formulations), even though several assays were common to both Phases.
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Affiliation(s)
- S D Gettings
- Cosmetic, Toiletry and Fragrance Association, Washington, DC 20036
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26
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Grafström RC, Dypbukt JM, Sundqvist K, Atzori L, Nielsen I, Curren RD, Harris CC. Pathobiological effects of acetaldehyde in cultured human epithelial cells and fibroblasts. Carcinogenesis 1994; 15:985-90. [PMID: 8200105 DOI: 10.1093/carcin/15.5.985] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The ability of acetaldehyde, a respiratory carcinogen present in tobacco smoke and automotive emissions, to affect cell viability, thiol status and intracellular Ca2+ levels and to cause DNA damage and mutations has been studied using cultured human cells. Within a concentration range of 3-100 mM, a 1 h exposure to acetaldehyde decreases colony survival and inhibits uptake of the vital dye neutral red in bronchial epithelial cells. Acetaldehyde also causes both DNA interstrand cross-links and DNA protein cross-links whereas no DNA single strand breaks are detected. The cellular content of glutathione is also decreased by acetaldehyde, albeit, without concomitant changes in the glutathione redox status or in the content of protein thiols. Transient or sustained increases in cytosolic Ca2+ occur within minutes following exposure of cells to acetaldehyde. Moreover, acetaldehyde significantly decreases the activity of the DNA repair enzyme O6-methylguanine-DNA methyltransferase. Finally, a 5 h exposure to acetaldehyde causes significant levels of 6-thioguanine resistance mutations in an established mutagenesis model involving skin fibroblasts. The results indicate that mM concentrations of acetaldehyde cause a wide range of cytopathic effects associated with multistep carcinogenesis. The fact that acetaldehyde, in relation to its cytotoxicity, causes comparatively higher genotoxicity and inhibits DNA repair more readily than other major aldehydes in tobacco smoke and automotive emissions is discussed.
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Affiliation(s)
- R C Grafström
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
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27
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Abstract
Clinical trials with tacrine (THA) and its principal (1-OH) metabolite (velnacrine) for the treatment of Alzheimer's disease have been hampered by adverse hepatic events that were undetected in preclinical studies. As part of integrated in vivo/in vitro efforts to characterize the role of metabolites in these events, cultured cells were evaluated for their suitability for further mechanistic studies. The relative cytotoxic potentials of THA, three monohydroxy metabolites of THA (including velnacrine, a racemate), the two velnacrine enantiomers, and several known and suspected dihydroxy velnacrine metabolites were determined. Cytotoxicity was evaluated in 24-hour cultures by morphology and by the Neutral Red Uptake Assay. All test articles were evaluated in primary rat hepatocytes and in a human hepatoma cell line (HepG2). THA and velnacrine were also tested in a rat hepatoma cell line (H4) and in primary dog hepatocytes. The metabolic competency of each cell type was determined. Sensitivity to THA and velnacrine was greatest in H4 cells, followed by primary rat and HepG2 cells; dog cells were least sensitive. In HepG2 cells, THA was clearly more cytotoxic (LC50:54 micrograms/ml) than its monohydroxy metabolites (LC50 values: 84 to 190 micrograms/ml); dihydroxy velnacrine metabolites were the least cytotoxic (LC50 values:251 to 434 micrograms/ml); the relative order was comparable in primary rat hepatocytes. Roles for reactive metabolites and/or altered metabolic capabilities of Alzheimer's patients are suggested.
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Affiliation(s)
- C J Viau
- Hoechst-Roussel Pharmaceuticals Inc., Somerville, NJ 08876
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28
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Abstract
Acrylic acid was tested for gene mutations in the in vitro CHO/HGPRT assay, for chromosome aberrations in CHO cells in culture, and for potential to induce unscheduled DNA synthesis in rat hepatocytes in culture. In vivo assays performed included the Drosophila sex-linked recessive lethal assay by both the feeding and injection routes, the in vivo cytogenetic assay in rat bone marrow cells after both a 1-day and 5-day oral dosing regimen, and a dominant lethal assay in mice by both an acute and 5-day dosing regimen. All results were negative (non-mutagenic) except for the in vitro chromosome aberration assay. This latter result is consistent with the previously reported possible clastogenic activity suggested by the results of the mouse lymphoma L5178Y TK locus assay in which a predominance of small-colony mutants was observed (Moore et al., Environmental and Molecular Mutagenesis 1988, 11, 49-63). The rapid clearance of acrylic acid in animals and the weight of evidence of genetic toxicity testing, including negative in vivo data in both somatic and germ cells, indicate a lack of genetic toxicity of acrylic acid in vivo.
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Affiliation(s)
- K L McCarthy
- Toxicology Department, Rohm and Haas Company, Spring House, PA 19477
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29
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Abstract
Lithium hypochlorite (LiOCl), the pool and spa sanitizer/algicide, was evaluated for genotoxicity in a battery of studies designed to evaluate potential mutagenicity, DNA damage and chromosome aberrations. LiOCl was not mutagenic in the Ames test when tested in Salmonella typhimurium strains TA98, TA100, TA1535, TA1537, TA1538 or in the hypoxanthine-guanine phosphoribosyl transferase (HGPRT) mutation assay in Chinese hamster ovary (CHO) cells without metabolic activation. LiOCl did not induce DNA damage in the unscheduled DNA synthesis assay using rat primary hepatocytes. Effects on metaphase chromosomes were evaluated in vitro in CHO cells at 12 and 18 h exposure without S9 and at 12 and 22 h following a 2 h exposure with S9. LiOCl induced a statistically significant increase in chromosome aberrations at the high dose only at both harvest times without S9 and at the late harvest time with S9. There were significant increases in chromosome aberrations at the low dose, low-mid and high doses, but not at the high mid-dose at the early harvest time with S9. However, LiOCl did not increase chromosome aberrations when tested orally in rats at maximally tolerated doses. Bone marrow cells, collected 6, 24 and 48 h after a single oral dose of LiOCl to rats (100, 500, 1000 mg/kg in males; 50, 250, 500 mg/kg in females) showed no increase in the incidence of aberrations. In general, the weight of the evidence indicates that LiOCl is not genotoxic.
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Affiliation(s)
- M L Weiner
- FMC Corporation, Chemical Research and Development Center, Princeton, NJ 08543
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30
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Steele VE, Morrissey RE, Elmore EL, Gurganus-Rocha D, Wilkinson BP, Curren RD, Schmetter BS, Louie AT, Lamb JC, Yang LL. Evaluation of two in vitro assays to screen for potential developmental toxicants. Fundam Appl Toxicol 1988; 11:673-84. [PMID: 3229591 DOI: 10.1016/0272-0590(88)90130-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
To evaluate two in vitro assays for their ability to detect known developmental toxicants and nontoxicants, a series of 44 coded compounds were assayed by two independent laboratories using standardized protocols. The two test systems were (1) the human embryonic palatal mesenchymal cell growth inhibition assay and (2) the mouse ovarian tumor cell attachment inhibition assay. After all compounds were tested, they were decoded and ranked according to the minimum IC50 value (the millimolar concentration of compound which inhibits growth or attachment by 50% compared to the solvent control) from either test. The in vitro test result concordance with established in vivo animal and human test results was examined over a wide range of concentration levels (above which the in vitro results were called positive and below which they were considered negative). A positive response from either test was defined as a positive in vitro response. Concordance was defined as the number of correct responses divided by the number of chemicals tested. At the 1 mM level, the concordance of data from the combined in vitro assays with the in vivo data was 66% in one laboratory and 58% in the other. The maximum agreement between the combined in vitro and in vivo data was reached at the 20 mM level, where there was a 73 and 74% concordance of results in the two laboratories. At that level there was a 16 and 10% incidence of false negative results, and a 54 and 77% incidence of false positive results. A portion of these false negative compounds may require metabolic activation. The use of either assay alone was not as accurate as using a positive result from either test. Agreement of the in vitro data at the 10 mM level with available human data was 71 and 75% for each laboratory. The data indicate that the two assays are complimentary and as such the combination of these assays could be useful as a preliminary screen to establish priorities for in vivo developmental toxicity testing.
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Affiliation(s)
- V E Steele
- Northrop Services, Inc., Research Triangle Park, North Carolina 27709
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O'Donoghue JL, Haworth SR, Curren RD, Kirby PE, Lawlor T, Moran EJ, Phillips RD, Putnam DL, Rogers-Back AM, Slesinski RS. Mutagenicity studies on ketone solvents: methyl ethyl ketone, methyl isobutyl ketone, and isophorone. Mutat Res 1988; 206:149-61. [PMID: 3050497 DOI: 10.1016/0165-1218(88)90154-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
3 ketone solvents (methyl ethyl ketone (MEK), methyl isobutyl ketone (MiBK), and isophorone) were tested for potential genotoxicity. The assays of MEK and MiBK included the Salmonella/microsome (Ames) assay, L5178Y/TK+/- mouse lymphoma (ML) assay, BALB/3T3 cell transformation (CT) assay, unscheduled DNA synthesis (UDS) assay, and micronucleus (MN) assay. Only the ML, UDS, and MN assays were conducted on samples of isophorone. No genotoxicity was found for MEK or isophorone. The presence of a marginal response only at the highest, cytotoxic concentration tested in the ML assay, the lack of reproducibility in the CT assay, and clearly negative results in the Ames assay, UDS and MN assays, suggest that MiBK is unlikely to be genotoxic in mammalian systems.
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Affiliation(s)
- J L O'Donoghue
- Health and Environment Laboratories, Eastman Kodak Company, Rochester, NY 14652-3615
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Abstract
Acrolein, a short-chain aldehyde encountered as a component of tobacco smoke and as a ubiquitous environmental contaminant, was tested for its toxic and mutagenic effects toward human fibroblast cells. We found that human cells characterized by a deficiency in DNA repair (cells from xeroderma pigmentosum (XP) patients) were much more sensitive (D37 approximately equal to 0.25 microM) to the cytotoxic effects of acrolein than were cells from normal individuals (D37 approximately equal to 0.8 microM). Acrolein was also strongly mutagenic to the XP cells (a dose response was observed between 0.2 and 0.8 microM acrolein); however acrolein did not induce an increase in the mutant frequency of normal fibroblasts. Possible reasons for this apparent lack of mutagenicity in normal human cells are discussed.
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Affiliation(s)
- R D Curren
- Microbiological Associates Inc., Rockville, MD 20850
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Curren RD, Putman DL, Yang LL, Haworth SR, Lawlor TE, Plummer SM, Harris CC. Genotoxicity of fecapentaene-12 in bacterial and mammalian cell assay systems. Carcinogenesis 1987; 8:349-52. [PMID: 3542273 DOI: 10.1093/carcin/8.2.349] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Fecapentaene-12 (Fec-12), a compound thought to be responsible for much of the mutagenicity in fecal extracts from groups at high risk for colon cancer, was assayed for genotoxic potential in a battery of bacterial and mammalian cell short-term assays. This compound demonstrated significant mutagenic activity with Salmonella typhimurium tester strains TA104, TA100 and TA98, inducing approximately 1400, 700 and 100 revertants/micrograms, respectively. Fec-12 caused dose-dependent increases in unscheduled DNA synthesis in both rat hepatocytes and human fibroblasts, indicating its potential genotoxicity to mammalian as well as bacterial cells. Finally, Fec-12 had the ability to induce neoplastic transformation in mouse BALB/c 3T3 cells in the absence of exogenous metabolic activation.
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Plummer SM, Grafstrom RC, Yang LL, Curren RD, Linnainmaa K, Harris CC. Fecapentaene-12 causes DNA damage and mutations in human cells. Carcinogenesis 1986; 7:1607-9. [PMID: 3742732 DOI: 10.1093/carcin/7.9.1607] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Fecapentaenes are mutagens found in human feces and may play a role in the pathogenesis of colon carcinoma. However, the genotoxic effects of fecapentaenes have not been previously studied in mammalian cells. We now report that fecapentaene-12 (fec-12), a prototype for these compounds, causes DNA single strand breaks, sister chromatid exchanges and mutations in cultured human fibroblasts. These results indicate that fec-12 is a potent genotoxic agent in human cells.
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Tu A, Hallowell W, Pallotta S, Sivak A, Lubet RA, Curren RD, Avery MD, Jones C, Sedita BA, Huberman E. An interlaboratory comparison of transformation in Syrian hamster embryo cells with model and coded chemicals. Environ Mutagen 1986; 8:77-98. [PMID: 3943499 DOI: 10.1002/em.2860080108] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Three independent laboratories tested eight "model" and five coded chemicals in the Syrian hamster embryo clonal transformation assay system to establish the intra- and interlaboratory reproducibility of the system and to identify sources of variability. When a common cell pool and the same lot of fetal calf serum were used, the three laboratories obtained consensus on the activity of eight model chemicals: five chemicals (benzo(a)pyrene, 7,12-dimethylbenz(a)anthracene, N-methyl-N'-nitro-N-nitrosoguanidine, nitroquinoline-N-oxide, and lead chromate) induced morphological transformation without exogenous metabolic activation and three (N-2-fluorenylacetamide, pyrene, and anthracene) produced no transformation response. Five coded chemicals (2,6-dichloro p-phenylenediamine, 4,4'-oxydianiline, cinnamyl anthranilate, dichlorvos, and reserpine), representative of environmental chemical classes, but not necessarily strong carcinogens, produced more equivocal responses in this interlaboratory study. Thus, while the assay can be used to distinguish between transforming and nontransforming chemicals in some cases, the intrinsic limitations in low transformation frequency and in achieving any dose-response results are major constraints to the use of this system in a routine testing program at the present time. Efforts to increase the transformation frequency or to amplify the expression of the transformed phenotype constitute some of the approaches which should be explored in order to overcome these limitations.
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Abstract
Formaldehyde, a common environmental pollutant, inhibits repair of O6-methylguanine and potentiates the mutagenicity of an alkylating agent, N-methyl-N-nitrosourea, in normal human fibroblasts. Because formaldehyde alone also causes mutations in human cells, the compound may cause genotoxicity by a dual mechanism of directly damaging DNA and inhibiting repair of mutagenic and carcinogenic DNA lesions caused by other chemical and physical carcinogens.
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Yang LL, Kouri RE, Curren RD. Xeroderma pigmentosum fibroblasts are more sensitive to asbestos fibers than are normal human fibroblasts. Carcinogenesis 1984; 5:291-4. [PMID: 6321052 DOI: 10.1093/carcin/5.2.291] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Xeroderma pigmentosum fibroblasts (XPF) are defective in the repair of certain DNA adducts. We show here that XPF cells are more sensitive to the toxic effects of chrysotile, amosite and crocidolite asbestos than are normal human fibroblasts (NF). XPF cells from different complementation groups have a sensitivity to chrysotile which parallels the degree of their DNA repair deficiency. In addition, the survival of normal cells after chrysotile exposure increases with time if they are kept from replicating, while the survival of XPF cells under the same circumstances does not change.
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Kouri RE, Rude TH, Curren RD, Brandt KR, Sosnowski RG, Schechtman LM, Benedict WF, Henry CJ. Biological activity of tobacco smoke and tobacco smoke-related chemicals. Environ Health Perspect 1979; 29:63-69. [PMID: 510243 PMCID: PMC1637371 DOI: 10.1289/ehp.792963] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
Exposure to whole cigarette smoke from reference cigarettes results in the prompt (peak activity is 6 hrs), but fairly weak (similar to 2 fold), induction of murine pulmonary microsomal monooxygenase activity. This activity can be detected by using as substrates either benzo(a)pyrene or ethoxyresorufin, and can be inhibited by treatment with cycloheximide or actinomycin D. Unlike the induction of pulmonary monooxygenases following intratracheal administration of 3-methylcholanthrene, these cigarette smoke-induced increases were not unequivocally linked to the Ah locus. Whole smoke condensate and fractions derived from these condensates can; a) induce pulmonary monooxygenase activity, b) inhibit benzo(a)pyrene metabolism in vitro, c) be metabolized to forms mutagenic to Salmonella typhimurium tester strains TA153, or TA98, d) transform C3H 10T1/2 cells in vitro, and e) enhance the carcinogenicity of benzo(a)pyrene in murine pulmonary tissue. A potentially important observation is that whereas hepatic tissue is capable of activating whole cigarette smoke condensate to mutagenic forms in vitro, murine pulmonary tissue does not seem capable of such activation. Although these pulmonary-derived tissue homogenates have significant AHH activity and can metabolize Aflatoxin B1, 2-aminofluorene and 7, 8-dihydro-7,8-dihydroxybenzo(a)pyrene to mutagenic forms, these homogenates fail to activate both cigarette smoke condensate and the pro-mutagen, 6-aminochrysene. These results are discussed with reference to the concept that whole cigarette smoke may be both a potential "initiator" and "promotor" of lung cancer in mice, and that this latter property may be the most important in determining cancer risk.
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Maher VM, Ouellette LM, Curren RD, McCormick JJ. Caffeine enhancement of the cytotoxic and mutagenic effect of ultraviolet irradiation in a xeroderma pigmentosum variant strain of human cells. Biochem Biophys Res Commun 1976; 71:228-34. [PMID: 962915 DOI: 10.1016/0006-291x(76)90272-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Maher VM, Ouellette LM, Curren RD, McCormick JJ. Frequency of ultraviolet light-induced mutations is higher in xeroderma pigmentosum variant cells than in normal human cells. Nature 1976; 261:593-5. [PMID: 934300 DOI: 10.1038/261593a0] [Citation(s) in RCA: 279] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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