Publications (4)10.86 Total impact
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Article: Blood concentrations of acrylonitrile in humans after oral administration extrapolated from in vivo rat pharmacokinetics, in vitro human metabolism, and physiologically based pharmacokinetic modeling.
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ABSTRACT: The present study defined a simplified physiologically based pharmacokinetic (PBPK) model for acrylonitrile in humans based on in vitro metabolic parameters determined using relevant liver microsomes, coefficients derived in silico, physiological parameters derived from the literature, and a prior previously developed PBPK model in rats. The model basically consists of a chemical absorption compartment, a metabolizing compartment, and a central compartment for acrylonitrile. Evaluation of a previous rat model was performed by comparisons with experimental pharmacokinetic values from blood and urine obtained from rats in vivo after oral treatment with acrylonitrile (30 mg/kg, a no-observed-adverse-effect level) for 14 days. Elimination rates of acrylonitrile in vitro were established using data from rat liver microsomes and from pooled human liver microsomes. Acrylonitrile was expected to be absorbed and cleared rapidly from the body in silico, as was the case for rats confirmed experimentally in vivo with repeated low-dose treatments. These results indicate that the simplified PBPK model for acrylonitrile is useful for a forward dosimetry approach in humans. This model may also be useful for simulating blood concentrations of other related compounds resulting from exposure to low chemical doses.Regulatory Toxicology and Pharmacology 11/2010; 58(2):252-8. · 2.43 Impact Factor -
Article: Human blood concentrations of cotinine, a biomonitoring marker for tobacco smoke, extrapolated from nicotine metabolism in rats and humans and physiologically based pharmacokinetic modeling.
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ABSTRACT: The present study defined a simplified physiologically based pharmacokinetic (PBPK) model for nicotine and its primary metabolite cotinine in humans, based on metabolic parameters determined in vitro using relevant liver microsomes, coefficients derived in silico, physiological parameters derived from the literature, and an established rat PBPK model. The model consists of an absorption compartment, a metabolizing compartment, and a central compartment for nicotine and three equivalent compartments for cotinine. Evaluation of a rat model was performed by making comparisons with predicted concentrations in blood and in vivo experimental pharmacokinetic values obtained from rats after oral treatment with nicotine (1.0 mg/kg, a no-observed-adverseeffect level) for 14 days. Elimination rates of nicotine in vitro were established from data from rat liver microsomes and from human pooled liver microsomes. Human biomonitoring data (17 ng nicotine and 150 ng cotinine per mL plasma 1 h after smoking) from pooled five male Japanese smokers (daily intake of 43 mg nicotine by smoking) revealed that these blood concentrations could be calculated using a human PBPK model. These results indicate that a simplified PBPK model for nicotine/cotinine is useful for a forward dosimetry approach in humans and for estimating blood concentrations of other related compounds resulting from exposure to low chemical doses.International Journal of Environmental Research and Public Health 09/2010; 7(9):3406-21. · 1.61 Impact Factor -
Article: High-speed screening of human ATP-binding cassette transporter function and genetic polymorphisms: new strategies in pharmacogenomics.
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ABSTRACT: Drug transporters represent an important mechanism in cellular uptake and efflux of drugs and their metabolites. Hitherto a variety of drug transporter genes have been cloned and classified into either solute carriers or ATP-binding cassette (ABC) transporters. Such drug transporters are expressed in various tissues such as the intestine, brain, liver, kidney, and, importantly, cancer cells, where they play critical roles in the absorption, distribution, and excretion of drugs. We developed high-speed functional screening and quantitative structure-activity relationship analysis methods to study the substrate specificity of ABC transporters and to evaluate the effect of genetic polymorphisms on their function. These methods would provide powerful and practical tools for screening synthetic and natural compounds, and the deduced data can be applied to the molecular design of new drugs. Furthermore, we demonstrate a new "SNP array" method to detect genetic polymorphisms of ABC transporters in human samples.Methods in Enzymology 02/2005; 400:485-510. · 2.04 Impact Factor -
Article: High-speed screening and QSAR analysis of human ATP-binding cassette transporter ABCB11 (bile salt export pump) to predict drug-induced intrahepatic cholestasis.
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ABSTRACT: Human ATP-binding cassette transporter ABCB11 (SPGP/BSEP) mediates the elimination of bile salts from liver cells and thereby plays a critical role in the generation of bile flow. In the present study, we have developed in vitro high-speed screening and quantitative structure-activity relationship (QSAR) analysis methods to investigate the interaction of ABCB11 with a variety of drugs. Plasma membrane vesicles prepared from insect cells overexpressing human ABCB11 were used to measure the ATP-dependent transport of [14C]taurocholate. Over 40 different drugs and natural compounds were tested to evaluate their interaction with ABCB11-mediated taurocholate transport. On the basis of the extent of inhibition, we have analyzed the QSAR to identify one set of chemical fragmentation codes closely associated with the inhibition of ABCB11. This approach can be used to predict compounds with a potential risk of drug-induced intrahepatic cholestasis.Molecular Pharmaceutics 3(3):252-65. · 4.78 Impact Factor
Top Journals
Institutions
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2005
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Tokyo Institute of Technology
- Department of Biomolecular Engineering
Tokyo, Tokyo-to, Japan
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