Characterization of the resistance mechanisms to diazinon, parathion and diazoxon
in the organophosphorus-resistant SKA strain of houseflies (Musca domestica L.
Paraoxon and diazoxon (Chem Service) were prepared as stocks, 200 mmol/L in methanol and acetonitrile, respectively, and stored at -80 [degrees]C.
Paraoxon and diazoxon stock solution concentrations were verified by HPLC analysis before use.
We diluted a 200-mmol/L diazoxon stock solution (in methanol) to 1.
However, that study did not take into consideration the fact that the R alloform of PON 1 has somewhat better catalytic efficiency for diazoxon
than the Q alloform both in vitro and in vivo (Li et al.
To characterize the functional genotype distribution (as assessed by DZOase/POase ratios) and activity levels of PON1 as contributors to the higher CVD in southern populations, in the present study we investigated PON1 activity levels with three substrates (paraoxon, diazoxon, and phenyl acetate) in the serum of African-American and Caucasian southerners within race, sex, and age groups.
Diazoxon was purchased from ChemService (West Chester, PA).
We measured the 2-isopropyl-4-methyl-6-hydroxypyrimidine (IMHP) released from diazoxon hydrolysis spectrophotometrically in a continuous assay according to the method described by Richter and Furlong (1999).
192] functional genotype distribution (as assessed by DZOase/POase ratios) and PONl enzymatic activities (paraoxon and diazoxon hydrolysis, phenyl acetate hydrolysis) in the serum of 200 African-American and Caucasian southerners.
Forty-four percent of black subjects had higher in vitro rates of paraoxon hydrolysis and lower rates of diazoxon
hydrolysis, consistent with the RR genotype that has been hypothesized to increase the risk of CVD.
We determined PON1 activities using three different substrates, phenyl acetate (arylesterase), paraoxon, and diazoxon
, and all three activities were decreased with increasing exposure level.