Details
Originalsprache | Englisch |
---|---|
Seiten (von - bis) | 68-78 |
Seitenumfang | 11 |
Fachzeitschrift | Mutation Research - Genetic Toxicology and Environmental Mutagenesis |
Jahrgang | 757 |
Ausgabenummer | 1 |
Frühes Online-Datum | 26 Juli 2013 |
Publikationsstatus | Elektronisch veröffentlicht (E-Pub) - 26 Juli 2013 |
Abstract
The HET-MN assay (hen's egg test for micronucleus induction) is different from other in vitro genotoxicity assays in that it includes toxicologically important features such as absorption, distribution, metabolic activation, and excretion of the test compound. As a promising follow-up to complement existing in vitro test batteries for genotoxicity, the HET-MN is currently undergoing a formal validation. To optimize the validation, the present study describes a critical analysis of previously obtained HET-MN data to check the experimental design and to identify the most appropriate statistical procedure to evaluate treatment effects. Six statistical challenges (I–VI) of general relevance were identified, and remedies were provided which can be transferred to similarly designed test methods: a Williams-type trend test is proposed for overdispersed counts (II) by means of a square-root transformation which is robust for small sample sizes (I), variance heterogeneity (III), and possible downturn effects at high doses (IV). Due to near-to-zero or even zero-count data occurring in the negative control (V), a conditional comparison of the treatment groups against the mean of the historical controls (VI) instead of the concurrent control was proposed, which is in accordance with US-FDA recommendations. For the modified Williams-type tests, the power can be estimated depending on the magnitude and shape of the trend, the number of dose groups, and the magnitude of the MN counts in the negative control. The experimental design used previously (i.e. six eggs per dose group, scoring of 1000 cells per egg) was confirmed. The proposed approaches are easily available in the statistical computing environment R, and the corresponding R-codes are provided.
ASJC Scopus Sachgebiete
- Biochemie, Genetik und Molekularbiologie (insg.)
- Genetik
- Umweltwissenschaften (insg.)
- Gesundheit, Toxikologie und Mutagenese
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in: Mutation Research - Genetic Toxicology and Environmental Mutagenesis, Jahrgang 757, Nr. 1, 26.07.2013, S. 68-78.
Publikation: Beitrag in Fachzeitschrift › Artikel › Forschung › Peer-Review
}
TY - JOUR
T1 - Statistical analysis of the hen's egg test for micronucleus induction (HET-MN assay)
AU - Hothorn, Ludwig A.
AU - Reisinger, Kerstin
AU - Wolf, Thorsten
AU - Poth, Albrecht
AU - Fieblinger, Dagmar
AU - Liebsch, Manfred
AU - Pirow, Ralph
N1 - Funding Information: The funding of the present study by the German Federal Institute for Risk Assessment (BfR) is greatfully acknowledged. The experimental data used in this study originate from a validation study, which is funded by the German Federal Ministry for Research and Technology (BMBF Funding Priority “Replacement methods of animal experiments”, funding code: 0315803). The authors are grateful to two anonymous referees for the helpful comments which considerably improved the article. Appendix A
PY - 2013/7/26
Y1 - 2013/7/26
N2 - The HET-MN assay (hen's egg test for micronucleus induction) is different from other in vitro genotoxicity assays in that it includes toxicologically important features such as absorption, distribution, metabolic activation, and excretion of the test compound. As a promising follow-up to complement existing in vitro test batteries for genotoxicity, the HET-MN is currently undergoing a formal validation. To optimize the validation, the present study describes a critical analysis of previously obtained HET-MN data to check the experimental design and to identify the most appropriate statistical procedure to evaluate treatment effects. Six statistical challenges (I–VI) of general relevance were identified, and remedies were provided which can be transferred to similarly designed test methods: a Williams-type trend test is proposed for overdispersed counts (II) by means of a square-root transformation which is robust for small sample sizes (I), variance heterogeneity (III), and possible downturn effects at high doses (IV). Due to near-to-zero or even zero-count data occurring in the negative control (V), a conditional comparison of the treatment groups against the mean of the historical controls (VI) instead of the concurrent control was proposed, which is in accordance with US-FDA recommendations. For the modified Williams-type tests, the power can be estimated depending on the magnitude and shape of the trend, the number of dose groups, and the magnitude of the MN counts in the negative control. The experimental design used previously (i.e. six eggs per dose group, scoring of 1000 cells per egg) was confirmed. The proposed approaches are easily available in the statistical computing environment R, and the corresponding R-codes are provided.
AB - The HET-MN assay (hen's egg test for micronucleus induction) is different from other in vitro genotoxicity assays in that it includes toxicologically important features such as absorption, distribution, metabolic activation, and excretion of the test compound. As a promising follow-up to complement existing in vitro test batteries for genotoxicity, the HET-MN is currently undergoing a formal validation. To optimize the validation, the present study describes a critical analysis of previously obtained HET-MN data to check the experimental design and to identify the most appropriate statistical procedure to evaluate treatment effects. Six statistical challenges (I–VI) of general relevance were identified, and remedies were provided which can be transferred to similarly designed test methods: a Williams-type trend test is proposed for overdispersed counts (II) by means of a square-root transformation which is robust for small sample sizes (I), variance heterogeneity (III), and possible downturn effects at high doses (IV). Due to near-to-zero or even zero-count data occurring in the negative control (V), a conditional comparison of the treatment groups against the mean of the historical controls (VI) instead of the concurrent control was proposed, which is in accordance with US-FDA recommendations. For the modified Williams-type tests, the power can be estimated depending on the magnitude and shape of the trend, the number of dose groups, and the magnitude of the MN counts in the negative control. The experimental design used previously (i.e. six eggs per dose group, scoring of 1000 cells per egg) was confirmed. The proposed approaches are easily available in the statistical computing environment R, and the corresponding R-codes are provided.
KW - HET-MN assay
KW - Historical control
KW - Williams-trend test
UR - http://www.scopus.com/inward/record.url?scp=84891552587&partnerID=8YFLogxK
U2 - 10.1016/j.mrgentox.2013.04.023
DO - 10.1016/j.mrgentox.2013.04.023
M3 - Article
C2 - 23892231
AN - SCOPUS:84891552587
VL - 757
SP - 68
EP - 78
JO - Mutation Research - Genetic Toxicology and Environmental Mutagenesis
JF - Mutation Research - Genetic Toxicology and Environmental Mutagenesis
SN - 1383-5718
IS - 1
ER -