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Paraoxon sensitive phenylvalerate hydrolase in assessing the severity of acute paraoxon poisoning


, : Paraoxon sensitive phenylvalerate hydrolase in assessing the severity of acute paraoxon poisoning. Journal of Toxicology. Clinical Toxicology 39(1): 27-31

Introduction: Intoxications with organophosphorous compounds, especially paraoxon, are frequent. Organophosphorous compounds inhibit serine hydrolases such as acetylcholine, butyrylcholine, and carboxyl esterases although acetylcholine and butyrylcholine are too sensitive to paraoxon to be useful markers of severity. They cannot show a dose-dependent inhibition during an acute organophosphorous compounds exposure because maximal enzyme inhibition is reached at very low organophosphorous compounds concentrations. Purpose: To determine in vitro the dose-effect relationship between the activity of the paraoxon-sensitive phenylvalerate hydrolase, a member of the carboxyl esterases family, and the paraoxon dose, and to assess its utility as a putatively less sensitive enzyme marker to monitor the severity of an acute paraoxon intoxication. Materials and Methods: Phenylvalerate hydrolase and butyrylcholine activities were determined in serum of nine healthy human volunteers before and after addition of different concentrations of paraoxon. The determination of phenyl-valerate hydrolase activity was carried out using a modification of the method described by Johnson. A commercially available kit was used to measure butyrylcholine activity. Results: Paraoxon inhibits phenyl-valerate hydrolase activity at concentrations above 10-9 M. Maximal inhibition (apprxeq50% of baseline) is achieved at concentrations above 2.5 X 10-7 M. The IC50 value of paraoxon for phenyl-valerate hydrolase is 34 +- 2 nM. The uninhibited phenyl-valerate hydrolase activity is due to paraoxon-resistant isoforms. Paraoxon begins inhibiting butyrylcholine activity at concentrations above 10-9 M. At concentrations above 5 X 10-5 M, no butyrylcholine activity is measurable. The IC50 value of paraoxon for butyrylcholine is 150 +- 23 nM. Conclusion: The paraoxon-sensitive subunit of phenyl-valerate hydrolase shows dose-dependent inhibition when exposed to paraoxon in vitro, but it is even more sensitive than butyrylcholine to paraoxon inhibition. Determinations of phenyl-valerate hydrolase activity to assess the severity of an acute organophosphorous compounds poisoning cannot be recommended, but phenyl-valerate hydrolase may have utility in worker surveillance.

US$19.90

PMID: 11327223

DOI: 10.1081/clt-100102876


Other references

Rauf-Khan, Ra, 1982: Holland: agricultural development: a lesson for Pakistan. Pakistan agriculture 4(14): 33

Simpson, 2000: Killer waves on the East coast?. Scientific American 283(4): 16-17

Hernandez, F.; Fernandez, C.; Diaz, J.C.; Diaz, J.J.; Cortegaza, P.L., 2004: Herbicide efficacy and selectivity in sugarcane of herbicide Krismat DG 75 (trifloxysulfuron+ametryn). Three small plot replicated trials were conducted in Granma (Jovellanos, dry season), Jose Smith Comas (Cardenas, rainy season) Estates, Matanzas Province, and in Argentina Estate (Florida, rainy season), Camaguey Province, and in a large demonstr...

Pantarotto C.; Salmona M.; Fanelli R.; Bianchi M.; Szczawinska K., 1981: Gas liquid chromatographic mass fragmentographic determination of saccharin in biological fluids. Saccharin is an artificial sweetener shown to cause bladder cancer in rats. A specific and sensitive method was described for the determination of saccharin in biological fluids. The compound was extracted as its methyl derivative following a salt...

Antonov N.S., 1981: Quantitative structure activity relationships based on sorption isotherm equations. Pharmaceutical Chemistry Journal (English Translation of Khimiko-Farmatsevticheskii Zhurnal) 15(10): 729-737

Matyas, D.E.; Essig, B.; Caron, J.B.; Bilek, U., 2008: What must entities do to comply with Deficit Reduction Act requirements for information on federal and state False Claims Act provisions?. Journal of Health & Life Sciences Law 1(1): 151, 153-62

Kas'yanov, V.L., 1996: Fall at the banks of the Smolenka River. Biologiya Morya (Vladivostok) 22(3): 203-204

Sedar, A.W., 1962: ELECTRON MICROSCOPY OF THE OXYNTIC CELL IN THE GASTRIC GLANDS OF THE BULLFROG, RANA CATESBIANA: III. Permanganate Fixation of the Endoplasmic Reticulum. Journal of Cell Biology 14(1): 152-156

Degtiareva, L.V.; Terzova, T.B.; Deĭneka, S.V.; Khvylia, O.A.; Markulan, D.Iu., 1985: Changes in the structure of the gastric and duodenal mucosa after selective proximal vagotomy. Vrachebnoe Delo: 25-28

Savage, M.O.; Drake, W.M.; Carroll, P.V.; Monson, J.P., 2004: Transitional care of GH deficiency: when to stop GH therapy. While the benefits of growth hormone (GH) therapy in adult hypopituitary patients with GH deficiency (GHD) are established, the role of continued GH therapy after final height in adolescent GH-deficient patients remains unclear. Preliminary data s...