Fifth Mississippi State Conference on Differential Equations and Computational Simulations,
Electron. J. Diff. Eqns., Conf. 10, 2002, pp. 89-99.

Modelling the interactions of mixtures of organophosphorus insecticides with cholinesterase

Russell. L. Carr, Howard W. Chambers, Janice E. Chambers, Seth F. Oppenheimer, & Jason R. Richardson

Abstract:
The organophosphorus (OP) insecticides are one of the most widely used and important insecticide classes. These insecticides exert toxicity through inhibition of the critical nervous system enzyme cholinesterase (ChE) which functions to rapidly destroy the ubiquitous neurotransmitter acetylcholine. When ChE is inhibited, the acetylcholine accumulates, causing hyperactivity within the cholinergic pathways. Considerable effort has gone into assessing the risks of various OP insecticides. Unfortunately, people are often exposed to different OP insecticides in different dosages at different or overlapping times. The usual statistical methods seem inadequate to the task of assessing the effect of OP mixtures. This paper will discuss a simple model using systems of ordinary differential equations. Using this model, we have had success in predicting the effect of cumulative in vitro OP compound exposure in terms of ChE inhibition using data from experiments measuring ChE inhibition by a single OP compound. We will describe our model and compare our simulations to in vitro experiments where binary mixtures have been used.

Published February 28, 2003.
Subject classifications: 92C45.
Key words: Reaction kinetics, reaction modelling.

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Russell L. Carr
Center for Environmental Health Sciences
P.O. Box 6100
Mississippi State University, MS 39762, USA
e-mail: rlcarr@cvm.msstate.edu
Howard W. Chambers
Department of Entomology and Plant Pathology
P.O. Box 9775, Mississippi State University, MS 39762, USA
Janice E. Chambers
Center for Environmental Health Sciences
P.O. Box 6100
Mississippi State University, MS 39762, USA
e-mail: chambers@cvm.msstate.edu
Seth F. Oppenheimer
Department of Mathematics and Statistics
Drawer MA
Mississippi State University, MS 39762, USA
e-mail: seth@math.msstate.edu
Jason R. Richardson
Center for Neurodegenerative Disease
Emory University
Whitehead Biomedical Research Building 575
615 Michael Street, Atlanta, GA 30322, USA
e-mail: jricha3@emory.edu

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