Article

Production of ES1 Plasma Carboxylesterase Knockout Mice for Toxicity Studies

Eppley Institute, University of Nebraska Medical Center, Omaha, Nebraska 68198-5950, USA.
Chemical Research in Toxicology (Impact Factor: 4.19). 09/2011; 24(11):1891-8. DOI: 10.1021/tx200237a
Source: PubMed

ABSTRACT The LD(50) for soman is 10-20-fold higher for a mouse than a human. The difference in susceptibility is attributed to the presence of carboxylesterase in mouse but not in human plasma. Our goal was to make a mouse lacking plasma carboxylesterase. We used homologous recombination to inactivate the carboxylesterase ES1 gene on mouse chromosome 8 by deleting exon 5 and by introducing a frame shift for amino acids translated from exons 6 to 13. ES1-/- mice have no detectable carboxylesterase activity in plasma but have normal carboxylesterase activity in tissues. Homozygous ES1-/- mice and wild-type littermates were tested for response to a nerve agent model compound (soman coumarin) at 3 mg/kg sc. This dose intoxicated both genotypes but was lethal only to ES1-/- mice. This demonstrated that plasma carboxylesterase protects against a relatively high toxicity organophosphorus compound. The ES1-/- mouse should be an appropriate model for testing highly toxic nerve agents and for evaluating protection strategies against the toxicity of nerve agents.

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Available from: Christopher M. Timperley, Jun 11, 2014
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    • "In general, carboxylesterase activity in sheep revelations greater sensitivity to organophosphorus compounds than other esterases (del Loandos et al., 2012) and its assessable activity is higher (Hatfield et al., 2011; Wang et al., 2011). Therefore, possible that the joint biochemical biomarker of carboxylesterase activities will provide an additional valuable indication of organophosphorus compounds exposure in sheep species than the measurement of other esterases alone (Duysen et al., 2011; Lee et al., 2011). Toward use enzyme activities, for example carboxylesterase as accurate and sensitive biomarkers of organophosphorus poisoning, it is significant not only that the enzymes are adequately characterised in the species in query, but also that the assays themselves are adequately healthy and accessible to permit their use to make measurements of activity of adequate accuracy and precision to detect delicate changes in activity. "
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    • "In general, carboxylesterase activity in sheep revelations greater sensitivity to organophosphorus compounds than other esterases (del Loandos et al., 2012) and its assessable activity is higher (Hatfield et al., 2011; Wang et al., 2011). Therefore, possible that the joint biochemical biomarker of carboxylesterase activities will provide an additional valuable indication of organophosphorus compounds exposure in sheep species than the measurement of other esterases alone (Duysen et al., 2011; Lee et al., 2011). Toward use enzyme activities, for example carboxylesterase as accurate and sensitive biomarkers of organophosphorus poisoning, it is significant not only that the enzymes are adequately characterised in the species in query, but also that the assays themselves are adequately healthy and accessible to permit their use to make measurements of activity of adequate accuracy and precision to detect delicate changes in activity. "
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    ABSTRACT: The purpose of this study was to investigate the freezing correlations between the storage -80 °C and -20 °C. A further aim was to establish a foundation for the applicability of carboxylesterase in sheep as biochemical biomarkers for the evaluation of exposure to organophosphorus pesticides. Carboxylesterase is an enzyme that is capable of hydrolysing a wide variety of carboxylic acid esters. Determination of carboxylesterase in blood contents is the appropriate tool for the diagnosis of organophosphorus exposures. Carboxylesterase were determined by the Clement and Erhardt method, adapted for a plate reader. Biochemical products are prevalent in animals destined for human ingesting in world with serious public health inferences. Animal handlers are at risk of pollution and can serve as source of pollution to susceptible hosts. Targeted pest regulator of poisoned animals, concerted veterinary efforts, professional health instruction, active attachment of animal careers are necessary for effective control. In general, a significant increasing was seen for carboxylesterase activities after 3 weeks at -80 ºC and linear regression of mean carboxylesterase observed in all individual samples on weeks of two freezing for plasma (R 2 = 0819; P < 0.001).
    Journal of Engineering and Applied Science 10/2012; available online(2051-0853):361-365.
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    • "mice completely deficient in plasma carboxylesterase activity were created by homologous recombination of the ES1 gene on mouse chromosome 8 [9]. The ES1 gene was inactivated by deleting exon 5 and introducing a frame shift for amino acids translated from exons 6 to 13, thus deleting the catalytic triad residues Ser, Glu, His. "
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    ABSTRACT: Mouse blood contains four esterases that detoxify organophosphorus compounds: carboxylesterase, butyrylcholinesterase, acetylcholinesterase, and paraoxonase-1. In contrast human blood contains the latter three enzymes but not carboxylesterase. Organophosphorus compound toxicity is due to inhibition of acetylcholinesterase. Symptoms of intoxication appear after approximately 50% of the acetylcholinesterase is inhibited. However, complete inhibition of carboxylesterase and butyrylcholinesterase has no known effect on an animal's well being. Paraoxonase hydrolyzes organophosphorus compounds and is not inhibited by them. Our goal was to determine the effect of plasma carboxylesterase deficiency on response to sublethal doses of 10 organophosphorus toxicants and one carbamate pesticide. Homozygous plasma carboxylesterase deficient ES1(-/-) mice and wild-type littermates were observed for toxic signs and changes in body temperature after treatment with a single sublethal dose of toxicant. Inhibition of plasma acetylcholinesterase, butyrylcholinesterase, and plasma carboxylesterase was measured. It was found that wild-type mice were protected from the toxicity of 12.5mg/kg parathion applied subcutaneously. However, both genotypes responded similarly to paraoxon, cresyl saligenin phosphate, diisopropylfluorophosphate, diazinon, dichlorvos, cyclosarin thiocholine, tabun thiocholine, and carbofuran. An unexpected result was the finding that transdermal application of chlorpyrifos at 100mg/kg and chlorpyrifos oxon at 14mg/kg was lethal to wild-type but not to ES1(-/-) mice, showing that with this organochlorine, the presence of carboxylesterase was harmful rather than protective. It was concluded that carboxylesterase in mouse plasma protects from high toxicity agents, but the amount of carboxylesterase in plasma is too low to protect from low toxicity compounds that require high doses to inhibit acetylcholinesterase.
    Chemico-biological interactions 12/2011; 195(3):189-98. DOI:10.1016/j.cbi.2011.12.006 · 2.98 Impact Factor
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