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Dail MB, Meek EC, Chambers HW, Chambers JE. In vitro P-glycoprotein activity does not completely explain in vivo efficacy of novel centrally effective oxime acetylcholinesterase reactivators. Drug Chem Toxicol 2018; 42:403-408. [PMID: 29722548 DOI: 10.1080/01480545.2018.1461902] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Novel-substituted phenoxyalkyl pyridinium oxime acetylcholinesterase (AChE) reactivators (US patent 9,227,937) that showed convincing evidence of penetration into the brains of intact rats were developed by our laboratories. The oximes separated into three groups based on their levels of brain AChE reactivation following exposure of rats to the sarin surrogate nitrophenyl isopropyl methylphosphonate (NIMP). P-glycoprotein (P-gp) is a major blood-brain barrier (BBB) transporter and requires ATP for efflux. To determine if P-gp affinity screening could be used to reduce animal use, we measured in vitro oxime-stimulated ATPase activity to see if the in vivo reactivation efficacies related to the oximes' functions as P-gp substrates. High efficacy oximes were expected to be poor P-gp substrates, thus remaining in the brain longer. The high efficacy oximes (24-35% brain AChE reactivation) were worse P-gp substrates than the low efficacy oximes (0-7% brain AChE reactivation). However, the oxime group with medium in vivo reactivation of 10-17% were even worse P-gp substrates than the high efficacy group so their reactivation ability was not reflected by P-gp export. The results suggest that in vitro P-gp ATPase activity can remove the low efficacy oximes from in vivo testing, but is not sufficient to differentiate between the top two tiers.
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Affiliation(s)
- Mary Beth Dail
- a Center for Environmental Health Sciences, Department of Basic Sciences , College of Veterinary Medicine, Mississippi State University, Mississippi State , MS , USA
| | - Edward Caldwell Meek
- a Center for Environmental Health Sciences, Department of Basic Sciences , College of Veterinary Medicine, Mississippi State University, Mississippi State , MS , USA
| | - Howard Wayne Chambers
- b Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology , Entomology Unit, Mississippi State University, Mississippi State , MS , USA
| | - Janice Elaine Chambers
- a Center for Environmental Health Sciences, Department of Basic Sciences , College of Veterinary Medicine, Mississippi State University, Mississippi State , MS , USA
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Coombes RH, Meek EC, Dail MB, Chambers HW, Chambers JE. Human paraoxonase 1 hydrolysis of nanomolar chlorpyrifos-oxon concentrations is unaffected by phenotype or Q192R genotype. Toxicol Lett 2014; 230:57-61. [PMID: 25093614 DOI: 10.1016/j.toxlet.2014.07.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 07/17/2014] [Accepted: 07/21/2014] [Indexed: 02/02/2023]
Abstract
The organophosphorus insecticide chlorpyrifos has been widely used. Its active metabolite chlorpyrifos-oxon (CPO) is a potent anticholinesterase and is detoxified by paraoxonase 1 (PON1). PON1 activity is influenced by numerous factors including a Q192R polymorphism. Using forty human blood samples bearing homozygous genotypes and either high or low activity phenotypes (as determined by high concentration assays of paraoxon and diazoxon hydrolysis) the serum PON1 hydrolysis of high (320 μM) and low (178 nM) CPO concentrations was assessed using direct or indirect spectrophotometric methods, respectively. PON1 activity at high CPO concentration reflected the phenotype and genotype differences; subjects with the high activity phenotype and homozygous for the PON1R192 alloform hydrolyzed significantly more CPO than subjects with the low activity phenotype and/or PON1Q192 alloform (high RR=11023±722, low RR=9467±798, high QQ=8809±672, low QQ=6030±1015 μmol CPO hydrolyzed/min/L serum). However, PON1 hydrolysis of CPO at the lower, more environmentally relevant concentration showed no significant differences between the PON1192 genotypes and/or between high and low activity phenotypes (high RR=231±27, low RR=219±52, high QQ=193±59, low QQ=185±43 nmol CPO/min/L serum). Low CPO concentrations were probably not saturating, so PON1 did not display maximal velocity and the PON1 genotype/phenotype might not influence the extent of metabolism at environmental exposures.
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Affiliation(s)
- R Hunter Coombes
- Basic Sciences Department and Center for Environmental Health Sciences, College of Veterinary Medicine, P.O. Box 6100, 240 Wise Center Drive, Mississippi State University, Mississippi State, MS, USA 39762-6100.
| | - Edward C Meek
- Basic Sciences Department and Center for Environmental Health Sciences, College of Veterinary Medicine, P.O. Box 6100, 240 Wise Center Drive, Mississippi State University, Mississippi State, MS, USA 39762-6100.
| | - Mary Beth Dail
- Basic Sciences Department and Center for Environmental Health Sciences, College of Veterinary Medicine, P.O. Box 6100, 240 Wise Center Drive, Mississippi State University, Mississippi State, MS, USA 39762-6100.
| | - Howard W Chambers
- Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology: Entomology Unit and Center for Environmental Health Sciences, Mississippi State University, Mississippi State, MS, USA 39762.
| | - Janice E Chambers
- Basic Sciences Department and Center for Environmental Health Sciences, College of Veterinary Medicine, P.O. Box 6100, 240 Wise Center Drive, Mississippi State University, Mississippi State, MS, USA 39762-6100.
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McDaniel CY, Dail MB, Wills RW, Chambers HW, Chambers JE. Paraoxonase 1 polymorphisms within a Mississippi USA population as possible biomarkers of enzyme activities associated with disease susceptibility. Biochem Genet 2014; 52:509-23. [PMID: 25027835 DOI: 10.1007/s10528-014-9663-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 06/23/2014] [Indexed: 01/22/2023]
Abstract
Paraoxonase (PON1) hydrolyzes paraoxon (PO) and diazoxon (DZO), active metabolites of insecticides parathion and diazinon. The PON1 gene has single nucleotide polymorphisms (SNPs) including a codon 192 arginine (R) to glutamine (Q) and methionine (M) to leucine (L) at codon 55. Hydrolysis of PO (POase), DZO (DZOase), dihydrocoumarin (lactonase), and phenyl acetate (arylesterase) were evaluated for associations with race, gender, age, and PON1 55/192 SNP genotypes. Variables were analyzed both individually and in combination. QQ individuals had higher lactonase (p < 0.001) than RR individuals. This might partially explain why predominantly RR African Americans have higher rates of coronary disease than predominantly QQ Caucasians. Significant (p < 0.001) differences in arylesterase were seen among genotypes with QQ and MM lowest whereas RR and LL were highest. This opposes the prevailing belief that arylesterase is unaffected by genotype and suggests that this activity cannot be used to quantify PON1 protein.
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Affiliation(s)
- Chiquita Y McDaniel
- Basic Sciences Department and Center for Environmental Health Sciences, College of Veterinary Medicine, Mississippi State University, P.O. Box 6100, 240 Wise Center Drive, Mississippi State, MS, 39762-6100, USA
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Dail MB, Pickin R, Crow JA, Chambers JE. The Effect ofIn VitroDieldrin Exposure on the Rat Paraoxonase 1 (Pon1) Promoter. J Biochem Mol Toxicol 2014; 28:224-31. [DOI: 10.1002/jbt.21557] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 01/14/2014] [Accepted: 01/24/2014] [Indexed: 11/08/2022]
Affiliation(s)
- Mary Beth Dail
- Center for Environmental Health Sciences and Department of Basic Sciences; College of Veterinary Medicine; Mississippi State University; Mississippi State MS USA
| | - Rebecca Pickin
- Center for Environmental Health Sciences and Department of Basic Sciences; College of Veterinary Medicine; Mississippi State University; Mississippi State MS USA
| | - John Allen Crow
- Center for Environmental Health Sciences and Department of Basic Sciences; College of Veterinary Medicine; Mississippi State University; Mississippi State MS USA
| | - Janice E. Chambers
- Center for Environmental Health Sciences and Department of Basic Sciences; College of Veterinary Medicine; Mississippi State University; Mississippi State MS USA
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Ali AO, Hohn C, Allen PJ, Ford L, Dail MB, Pruett S, Petrie-Hanson L. The effects of oil exposure on peripheral blood leukocytes and splenic melano-macrophage centers of Gulf of Mexico fishes. Mar Pollut Bull 2014; 79:87-93. [PMID: 24405733 DOI: 10.1016/j.marpolbul.2013.12.036] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2013] [Revised: 12/05/2013] [Accepted: 12/12/2013] [Indexed: 06/03/2023]
Abstract
In August and November 2010 we collected and examined peripheral blood and tissues from three species of Gulf of Mexico fish. Findings were compared to non-exposed control fish. The leukocyte counts of exposed alligator gar were not significantly different from controls, while exposed Gulf killifish and sea trout had significantly decreased lymphocyte counts. Liver ethoxyresorufin-O-deethylase (EROD) values from sea trout were significantly greater than control sea trout EROD values, suggesting poly aromatic hydrocarbon exposure. Splenic melano-macrophage centers (MMCs) from exposed sea trout and Gulf killifish showed a significant increase in number compared to non-exposed fish. Sea trout splenic MMCs were also significantly greater in size. These findings suggest that Gulf fish sampled were exposed to crude oil from the Macondo well and were in a lymphopenic or immuno-compromised state.
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Affiliation(s)
- Ahmad Omar Ali
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA
| | - Claudia Hohn
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA
| | - Peter J Allen
- Department of Wildlife, Fisheries and Aquaculture, College of Forest Resources, Mississippi State University, Mississippi State, MS 39762, USA
| | - Lorelei Ford
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA
| | - Mary Beth Dail
- Center for Environmental Health Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA
| | - Stephen Pruett
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA
| | - Lora Petrie-Hanson
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA.
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MacGregor CH, Arora SK, Hager PW, Dail MB, Phibbs PV. The nucleotide sequence of the Pseudomonas aeruginosa pyrE-crc-rph region and the purification of the crc gene product. J Bacteriol 1996; 178:5627-35. [PMID: 8824606 PMCID: PMC178400 DOI: 10.1128/jb.178.19.5627-5635.1996] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The gene (crc) responsible for catabolite repression control in Pseudomonas aeruginosa has been cloned and sequenced. Flanking the crc gene are genes encoding orotate phosphoribosyl transferase (pyrE) and RNase PH (rph). New crc mutants were constructed by disruption of the wild-type crc gene. The crc gene encodes an open reading frame of 259 amino acids with homology to the apurinic/apyrimidinic endonuclease family of DNA repair enzymes. However, crc mutants do not have a DNA repair phenotype, nor can the crc gene complement Escherichia coli DNA repair-deficient strains. The crc gene product was overexpressed in both P. aeruginosa and in E. coli, and the Crc protein was purified from both. The purified Crc proteins show neither apurinic/apyrimidinic endonuclease nor exonuclease activity. Antibody to the purified Crc protein reacted with proteins of similar size in crude extracts from Pseudomonas putida and Pseudomonas fluorescens, suggesting a common mechanism of catabolite repression in these three species.
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Affiliation(s)
- C H MacGregor
- Department of Microbiology and Immunology, East Carolina University School of Medicine, Greenville, North Carolina 27858, USA
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