Biosensor Detection of Neuropathy Target Esterase in Whole Blood as a Biomarker of Exposure to Neuropathic Organophosphorus Compounds

Abstract

Public Reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. 44379.1-LSNeuropathy target esterase (NTE) is the target for neuropathic organophosphorus compounds (OPs) that produce delayed neurotoxicity (OPIDN). Inhibition/aging of brain NTE predicts the potential for OPIDN in animal models. Lymphocyte NTE has also found use as a biomarker of human exposure to neuropathic OPs. Recently, a sensitive NTE biosensor was developed using a tyrosinase carbon-paste electrode for amperometric (Amp) detection of phenol produced by hydrolysis of the substrate, phenyl valerate. The I50 (20 min at 37 °C) for N,N'-di-2 propylphosphorodiamidofluoridate (mipafox) against hen lymphocyte NTE was 6.94 ± 0.28 •uM (Amp) and 6.02 ± 0.71 uM colorimetrically (Col). For O,O-di-1-propyl O-2,2-dichlorvinyl phosphate (PrDChVP), the I50 against hen brain NTE was 39 ± 8 nM (Amp) and 42 ± 2 nM (Col). I50 values (Amp) for PrDChVP against hen and human blood NTE were 66 ± 3 and 70 ± 14 nM, respectively. NTE activities in brain, lymphocytes, and blood were measured 24 h after dosing hens with PrDChVP. NTE inhibition was highly correlated between brain and lymphocyte (r = 0.994) and brain and blood (r = 0.997). Biosensor NTE assay for whole blood could serve as a biomarker of exposure to neuropathic OPs.12 (excluding cover forms) Biosensor, Delayed neurotoxicity, Mipafox, Organophosphorus compounds (OPs), Neuropathy target esterase (NTE).

Neuropathy target esterase in mouse whole blood as a biomarker of exposure to neuropathic organophosphorus compounds

“…Brain NTE activity was determined in 9S supernatants by the colorimetric method of Johnson ( Johnson, 1977) with slight modifications (Kayyali et al, 1991;Makhaeva et al, 2003). All reactions were carried out at 37°C for the entire assay.…”

“…Blood NTE activity was determined in 1/100 (v/v) blood hemolysates according to the differential inhibition method of Johnson (Johnson, 1977) with an electrochemical endpoint as described previously (Sigolaeva et al, 2001(Sigolaeva et al, , 2013bMakhaeva et al, 2003). Briefly, 1/100 (v/v) blood hemolysate samples (300 μl) were preincubated for 20 min at 37°C in 50 mM Tris-HCl/0.2 mM EDTA (pH 8.0 at 37°C) with 50 μM PO (sample B) or 50 μM PO plus 250 μM MIP (sample C) (final inhibitor concentrations in a final volume of 400 μl).…”

“…The biosensor was used to establish correlations of NTE inhibitions in whole blood with that in lymphocytes and the brain 24 h after dosing hens with a neuropathic OP compound, O,O-dipropyl-Odichlorvinylphosphate (PrDChVP) (Makhaeva et al, , 2007. These studies indicated that hen whole blood NTE can be assayed and used as a biomarker of exposure to neuropathic OP compounds (Sigolaeva et al, 2001;Makhaeva et al, 2003Makhaeva et al, , 2007Sokolovskaya et al, 2005).…”

Neuropathy Target Esterase Biosensor

“…Neuropathy Target Esterase (NTE), is a membrane-bound protein found in neurons of vertebrates (Glynn, 1999;Atkins & Glynn, 2000;van Tienhoven et al, 2002;Li et al, 2003;Makhaeva et al, 2003;Kropp et al, 2004), has been shown to be necessary for embryonic development in mice, and is believed to be involved in cell-signaling pathways and lipid trafficking (Glynn, 1999). NTE has serine esterase activity and can hydrolyze ester, peptide, and amide bonds.…”

“…In the second step, the concentration of phenol in the solution is determined either colorimetrically, in the presence of 4-amino antipyrine (Kayyali et al, 1991), or electrochemically, in the presence of tyrosinase enzyme (Sigolaeva et al, 2001;Sokolovskaya et al, 2005). Tyrosinase converts phenol first to catechol and then to o-quinone, which can be measured electrochemically at an electrode (Makhaeva et al, 2003). The current generated by the electrode increases with the amount of o-quinone present, thus giving an indirect measurement of the amount of NTE esterase activity present during the first step.…”