Publications by authors named "Dick Schoutsen"

6 Publications

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Visualizing Compound Distribution during Zebrafish Embryo Development: The Effects of Lipophilicity and DMSO.

Birth Defects Res B Dev Reprod Toxicol 2015 Dec 11;104(6):253-72. Epub 2015 Dec 11.

WIL Research Europe B.V, Hambakenwetering 7, 's-Hertogenbosch, The Netherlands.

The predictability of the zebrafish embryo model is highly influenced by internal exposure of the embryo/larva. As compound uptake is likely to be influenced by factors such as lipophilicity, solvent use, and chorion presence, this article focuses on investigating their effects on compound distribution within the zebrafish embryo. To visualize compound uptake and distribution, zebrafish embryos were exposed for 96 hr, starting at 4 hr postfertilization, to water-soluble dyes: Schiff's reagent (logP -4.63), Giemsa stain (logP -0.77), Van Gierson stain (logP 1.64), Cresyl fast violet (logP 3.5), Eosine Y (logP 4.8), Sudan III (logP 7.5), and Oil red O (logP 9.81), with and without 1% dimethyl-sulfoxide (DMSO). Three additional compounds were used to analytically determine the uptake and distribution: Acyclovir (logP -1.56), Zidovudine (logP 0.05), and Metoprolol Tartrate Salt (logP 1.8). Examinations were performed every 24 hr. Both methods (visualization and specific analysis) showed that exposure to higher logP values results in higher compound uptake. Specific analysis showed that for lipophilic compounds >90% of compound is taken up by the embryo. For hydrophilic compounds, >90% of compound within the complete egg could not be associated to embryo or chorion and is probably distributed into the perivitelline space. Overall, internal exposure analyses on at least two occasions (i.e., before and after hatching) is crucial for interpretation of zebrafish embryotoxicity data, especially for compounds with extreme logP values. DMSO did not affect exposure when examined with the visualization method, however, this method might be not sensitive enough to draw hard conclusions.
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http://dx.doi.org/10.1002/bdrb.21166DOI Listing
December 2015

ICP-MS in drug development: high-throughput analysis of strontium and calcium in bone, tissue and plasma.

Bioanalysis 2013 Dec;5(23):2875-87

WIL Research Europe B.V., Hambakenwetering 7, 5231DD, 's-Hertogenbosch, The Netherlands.

Background: The high-throughput analysis of strontium and calcium in plasma, tissue and bone (femur) using inductively coupled plasma-MS is described. Method validation, the results and experience obtained during sample analysis are highlighted.

Results: The different matrices were destructed with concentrated nitric acid by heating at 60°C overnight. Using this approach it was possible to analyze large numbers of samples in parallel.

Conclusion: Inductively coupled plasma-MS proved to be a highly sensitive, robust and efficient technique for the analysis of several different biological samples. A total of 6767 samples were analyzed, and the performance of the method was illustrated by the fact that only 0.2% of the samples had to be reanalyzed due to anomalous results and ISR for all matrices fulfilled the acceptance criteria.
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http://dx.doi.org/10.4155/bio.13.259DOI Listing
December 2013

Recommendations on bioanalytical method stability implications of co-administered and co-formulated drugs by Global CRO Council for Bioanalysis (GCC).

Bioanalysis 2012 Sep;4(17):2117-26

Advion Bioanalytical Laboratories, Quintiles, NY, USA.

An open letter written by the Global CRO Council for Bioanalysis (GCC) describing the GCC survey results on stability data from co-administered and co-formulated drugs was sent to multiple regulatory authorities on 14 December 2011. This letter and further discussions at different GCC meetings led to subsequent recommendations on this topic of widespread interest within the bioanalytical community over the past 2 years.
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http://dx.doi.org/10.4155/bio.12.192DOI Listing
September 2012

Conference report: the 3rd Global CRO Council for Bioanalysis at the International Reid Bioanalytical Forum.

Bioanalysis 2011 Dec;3(24):2721-7

Accelera, Nerviano, Italy.

The 3rd Global CRO Council Closed Forum was held on the 3rd and 4th July 2011 in Guildford, United Kingdom, in conjunction with the 19th International Reid Bioanalytical Forum. In attendance were 21 senior-level representatives from 19 CROs on behalf of nine European countries and, for many of the attendees, this occasion was the first time that they had participated in a GCC meeting. Therefore, this closed forum was an opportunity to increase awareness of the aim of the GCC and how it works, share information about bioanalytical regulations and audit findings from different agencies, their policies and procedures and also to discuss some topics of interest and aim to develop ideas and provide recommendations for bioanalytical practices at future GCC meetings in Europe.
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http://dx.doi.org/10.4155/bio.11.242DOI Listing
December 2011