@article{usmani_karoly_hodgson_rose_2004, title={In vitro sulfoxidation of thioether compounds by human cytochrome P450 and flavin-containing monooxygenase isoforms with particular reference to the CYP2C subfamily}, volume={32}, ISSN={["1521-009X"]}, DOI={10.1124/dmd.32.3.333}, abstractNote={Cytochrome P450 (P450) and flavin-containing monooxygenase (FMO) enzymes are major catalysts involved in the metabolism of xenobiotics. The sulfoxidation of the thioether pesticides, phorate, disulfoton, sulprofos, and methiocarb, was investigated. Using pooled human liver microsomes (HLMs), thioether compounds displayed similar affinities; however, phorate and disulfoton displayed higher intrinsic clearance rates than either sulprofos or methiocarb. The sulfoxidation of thioethers by HLMs was found to be predominantly P450-driven (85-90%) compared with FMO (10-15%). Among 16 cDNA-expressed human P450 isoforms and 3 human FMO isoforms examined, the following isoforms and their polymorphisms had the highest rates for sulfoxidation, as follows: phorate, CYP1A2, 3A4, 2B6, 2C9*1, 2C18, 2C19, 2D6*1, and FMO1; disulfoton, CYP1A2, 3A4, 2B6, 2C9*1, 2C9*2, 2C18, 2C19, 2D6*1, and FMO1; sulprofos, CYP1A1, 1A2, 3A4, 2C9*1, 2C9*2, 2C9*3, 2C18, 2C19, 2D6*1, and FMO1; methiocarb, CYP1A1, 1A2, 3A4, 2B6, 2C9*1, 2C19, 2D6*1, and FMO1. Among these isoforms, members of the CYP2C subfamily often had the highest affinities and clearance rates. Moreover, sulfaphenazole, a CYP2C9 competitive inhibitor, inhibited disulfoton sulfoxidation by CYP2C9 (IC50 0.84 microM) as well as in HLMs. Ticlopidine, a CYP2C19 mechanism-based inhibitor, inhibited disulfoton sulfoxidation by CYP2C19 (IC50 after coincubation, 43.5 microM; IC50 after preincubation, 4.3 microM) and also in HLMs. Our results indicate that current models of the substrate binding site of the CYP2C subfamily would not effectively predict thioether pesticide metabolism. Thus, the substrate specificity of CYP2Cs is more extensive than is currently believed, and some reevaluation of structure-activity relationships may be required.}, number={3}, journal={DRUG METABOLISM AND DISPOSITION}, author={Usmani, KA and Karoly, ED and Hodgson, E and Rose, RL}, year={2004}, month={Mar}, pages={333–339} }
 @article{karoly_rose_2001, title={Sequencing, expression, and characterization of cDNA expressed flavin-containing monooxygenase 2 from mouse}, volume={15}, ISSN={["1099-0461"]}, DOI={10.1002/jbt.10009}, abstractNote={Abstract}, number={6}, journal={JOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY}, author={Karoly, ED and Rose, RL}, year={2001}, pages={300–308} }
 @article{karoly_rose_thompson_hodgson_rock_roe_1996, title={Monooxygenase, esterase, and glutathione transferase activity associated with azinphosmethyl resistance in the tufted apple bud moth, Platynota idaeusalis}, volume={55}, ISSN={["0048-3575"]}, DOI={10.1006/pest.1996.0040}, abstractNote={Azinphosmethyl-selected tufted apple bud moths were compared to susceptible and reverted strains with respect to possible metabolic mechanisms of resistance within the third instar, fifth instar, and adults. Based upon bioassays conducted by topical application with azinphosmethyl, LD50s were as high as 867-fold in the selected strain as compared to that seen in susceptible bud moths. The LD50 of the reverted strain was intermediate to that of the susceptible and selected insects at all stages studied. Glutathione transferase activity measured with 1-chloro-2,4-dinitrobenzene was elevated in the selected strain 1.6- and 2.2-fold as compared to third and fifth stadium susceptible bud moths, respectively. No consistent strain differences were noted for 1,2-dichloro-4-nitrobenzene. Cytochrome P450 content and P450 mRNA was not significantly different in fifth instars of the susceptible and selected strain. However, there was a 2.7- and 1.9-fold increase in benzphetamine and p-nitroanisole metabolism, respectively, in the guts of azinphosmethyl-selected fifth instars. Benzo[a]pyrene metabolism was elevated 2.4-fold in the carcass of selected bud moths and no differences were noted for methoxyresorufrin in either gut or carcass. Susceptible fifth instars demonstrated a reduced rate of metabolism of azinphosmethyl to the oxon and methyl benzazamide. Piperonyl butoxide failed to synergize azinphosmethyl toxicity. Esterase activity measured with 1-naphthyl acetate and p-nitrophenyl acetate was elevated in selected larvae compared to that seen in susceptible tufted apple bud moths in both larvae and adults. This increased esterase activity was attributed to several isoforms as resolved by analytical isoelectric focusing. One of these forms was consistently overexpressed in all of the life stages examined. Pretreatment of selected fifth instars with S,S,S-tributylphosphorotrithioate increased the toxicity of azinphosmethyl 400-fold and had minimal effect on toxicity in susceptible insects. It appears that multiple hydrolases are the primary metabolic factor in azinphosmethyl resistance in the tufted apple bud moth.}, number={2}, journal={PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY}, author={Karoly, ED and Rose, RL and Thompson, DM and Hodgson, E and Rock, GC and Roe, RM}, year={1996}, month={Jun}, pages={109–121} }