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- Asp, Vendela, et al.
(författare)
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Chiral effects in adrenocorticolytic action of o,p'-DDD (mitotane) in human adrenal cells
- 2010
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Ingår i: Xenobiotica. - : Informa UK Limited. - 0049-8254 .- 1366-5928. ; 40:3, s. 177-183
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Tidskriftsartikel (refereegranskat)abstract
- 1. Adrenocortical carcinoma (ACC) is a rare malignant disease with poor prognosis. The main pharmacological choice, o,p'-DDD (mitotane), produces severe adverse effects. 2. Since o,p'-DDD is a chiral molecule and stereoisomers frequently possess different pharmacokinetic and/or pharmacodynamic properties, we isolated the two o,p'-DDD enantiomers, (R)-(+)-o,p'-DDD and (S)-(-)-o,p'-DDD, and determined their absolute structures. 3. The effects of each enantiomer on cell viability and on cortisol and dehydroepiandrosterone (DHEA) secretion in the human adrenocortical cell line H295R were assessed. We also assayed the o, p'-DDD racemate and the m,p'- and p,p'-isomers. 4. The results show small but statistically significant differences in activity of the o, p'-DDD enantiomers for all parameters tested. The three DDD isomers were equally potent in decreasing cell viability, but p, p'- DDD affected hormone secretion slightly less than the o,p'- and m,p'-isomers. 5. The small chiral differences in direct effects on target cells alone do not warrant single enantiomer administration, but might reach importance in conjunction with possible stereochemical effects on pharmacokinetic processes in vivo.
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| 2. |
- Bergman, Åke, et al.
(författare)
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Manufacturing doubt about endocrine disrupter science : A rebuttal of industry-sponsored critical comments on the UNEP/WHO report "State of the Science of Endocrine Disrupting Chemicals 2012"
- 2015
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Ingår i: Regulatory toxicology and pharmacology. - : Academic Press. - 0273-2300 .- 1096-0295. ; 73:3, s. 1007-1017
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Tidskriftsartikel (refereegranskat)abstract
- We present a detailed response to the critique of "State of the Science of Endocrine Disrupting Chemicals 2012" (UNEP/WHO, 2013) by financial stakeholders, authored by Lamb et al. (2014). Lamb et al.'s claim that UNEP/WHO (2013) does not provide a balanced perspective on endocrine disruption is based on incomplete and misleading quoting of the report through omission of qualifying statements and inaccurate description of study objectives, results and conclusions. Lamb et al. define extremely narrow standards for synthesizing evidence which are then used to dismiss the UNEP/WHO 2013 report as flawed. We show that Lamb et al. misuse conceptual frameworks for assessing causality, especially the Bradford-Hill criteria, by ignoring the fundamental problems that exist with inferring causality from empirical observations. We conclude that Lamb et al.'s attempt of deconstructing the UNEP/WHO (2013) report is not particularly erudite and that their critique is not intended to be convincing to the scientific community, but to confuse the scientific data. Consequently, it promotes misinterpretation of the UNEP/WHO (2013) report by non-specialists, bureaucrats, politicians and other decision makers not intimately familiar with the topic of endocrine disruption and therefore susceptible to false generalizations of bias and subjectivity.
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| 3. |
- Bergman, Åke, et al.
(författare)
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Science and policy on endocrine disrupters must not be mixed : a reply to a "common sense" intervention by toxicology journal editors
- 2013
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Ingår i: Environmental Health. - : BioMed Central (BMC). - 1476-069X. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- The "common sense" intervention by toxicology journal editors regarding proposed European Union endocrine disrupter regulations ignores scientific evidence and well-established principles of chemical risk assessment. In this commentary, endocrine disrupter experts express their concerns about a recently published, and is in our considered opinion inaccurate and factually incorrect, editorial that has appeared in several journals in toxicology. Some of the shortcomings of the editorial are discussed in detail. We call for a better founded scientific debate which may help to overcome a polarisation of views detrimental to reaching a consensus about scientific foundations for endocrine disrupter regulation in the EU.
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| 8. |
- Hermansson, Veronica, et al.
(författare)
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Comparative CYP-dependent binding of the adrenocortical toxicants 3-methylsulfonyl-DDE and o,p′-DDD in Y-1 adrenal cells
- 2007
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Ingår i: Archives of Toxicology. - : Springer Science and Business Media LLC. - 0340-5761 .- 1432-0738. ; 81:11, s. 793-801
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Tidskriftsartikel (refereegranskat)abstract
- The environmental pollutant 3-MeSO2–DDE [2-(3-methylsulfonyl-4-chlorophenyl)-2-(4-chlorophenyl)-1,1-dichloroethene] is an adrenocortical toxicant in mice, specifically in the glucocorticoid-producing zona fasciculata, due to a cytochrome P450 11B1 (CYP11B1)-catalysed bioactivation and formation of covalently bound protein adducts. o,p′-DDD [2-(2-chlorophenyl)-2-(4-chlorophenyl)-1,1-dichloroethane] is toxic and inhibits steroidogenesis in the human adrenal cortex after bioactivation by unidentified CYPs, but does not exert any toxic effects on the mouse adrenal. As a step towards determining in vitro/in vivo relationships for the CYP-catalysed binding and toxicity of 3-MeSO2–DDE and o,p′-DDD, we have investigated the irreversible protein binding of these two toxicants in the murine adrenocortical cell line Y-1. The irreversible binding of 3-MeSO2–DDE previously demonstrated in vivo was successfully reproduced and could be inhibited by the CYP-inhibitors etomidate, ketoconazole and metyrapone. Surprisingly, o,p′-DDD reached similar levels of binding as 3-MeSO2–DDE. The binding of o,p′-DDD was sensitive to etomidate and ketoconazole, but not to metyrapone. Moreover, GSH depletion increased the binding of 3-MeSO2–DDE, but not of o,p′-DDD, indicating an important role of GSH conjugation in the detoxification of the 3-MeSO2–DDE-derived reactive metabolite. In addition, the specificity of CYP11B1 in activating 3-MeSO2–DDE was investigated using structurally analogous compounds. None of the analogues produced histopathological lesions in the mouse adrenal in vivo following a single i.p. injection of 100 mg/kg body weight, but two of the compounds were able to decrease the irreversible binding of 3-MeSO2–DDE to Y-1 cells. These results indicate that the bioactivation of 3-MeSO2–DDE by CYP11B1 is highly structure-dependent. In conclusion, both 3-MeSO2–DDE and o,p′-DDD bind irreversibly to Y-1 cells despite differences in binding and adrenotoxicity in mice in vivo. This reveals a notable in vitro/in vivo discrepancy, the contributing factors of which remain unexplained. We consider the Y-1 cell line as appropriate for studies of the cellular mechanisms behind the adrenocortical toxicity of these substances.
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| 10. |
- Hermansson, Veronica, et al.
(författare)
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Pharmacokinetics of the adrenocorticolytic compounds 3-methylsulphonyl-DDE and o,p′-DDD (mitotane) in Minipigs
- 2008
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Ingår i: Cancer Chemotherapy and Pharmacology. - : Springer Science and Business Media LLC. - 0344-5704 .- 1432-0843. ; 61:2, s. 267-274
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Tidskriftsartikel (refereegranskat)abstract
- The pharmacokinetics of the adrenocorticolytic drug candidate 3-Methylsulphonyl-DDE (3-MeSO2-DDE) and the anticancer drug o,p′-DDD (mitotane) were studied in Göttingen minipigs. The animals were given 3-MeSO2-DDE or o,p′-DDD as single oral doses (30 mg/kg). Concentrations in plasma and subcutaneous fat were measured by gas chromatography at different time points during 180 days. Maximal plasma concentrations appeared within 24 h for both compounds, but were about 2 times higher for 3-MeSO2-DDE. o,p′-DDD plasma concentrations declined rapidly to low levels during 4 days. 3-MeSO2-DDE also decreased rapidly, but remained at high concentrations throughout the study. In fat, 3-MeSO2-DDE reached about 25-fold higher levels than o,p′-DDD at 30 days, and both substances were eliminated slowly from this tissue. 3-MeSO2-DDE liver concentrations were about 18-fold higher than those in plasma at 180 days. In contrast, o,p′-DDD liver and plasma levels were about equal at 180 days. o,p′-DDD had roughly 45 times larger CL/F than 3-MeSO2-DDE, confirming that the elimination of this compound was more rapid. Both compounds were characterised by their localisation and retention in fat tissue, and the individual size of the fat stores clearly determined the plasma concentrations. It is concluded that although 3-MeSO 2-DDE is an interesting candidate for therapeutic use due to its potential characteristics to specifically target adrenocortical tumour cells the slow elimination of the compound might make it challenging to design appropriate dosage regimes.
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