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A conversion factor between two cholinesterase assays and its application in establishing a normal range for human RBC AChE.

Authors

Arrieta-DE; Nihart-VM; Henderson-JD; McCurdy-S; Lefkowitz-LJ; Wilson-BW

Source

Toxicologist 2005 Mar; 84(Suppl 1):262

Link

http://www.toxicology.org/AI/Pub/tox/2005Tox.pdf 

NIOSHTIC No.

20026468 

Abstract

The Cholinesterase (ChE) Reference Laboratory (CRL) at the US Army Center for Health Promotion and Preventive Medicine (USACHPPM) uses a modification of the delta pH method of Michel to annually analyze over 15,000 blood specimens from personnel that predominantly work at chemical agent storage sites and chemical demilitarization facilities. UC Davis and CRL are collaborating to derive a conversion factor between the delta pH and the colorimetric Ellman ChE assays. The factor is used to estimate a normal range of Ellman determined human blood acetylcholinesterase (AChE) levels based on CHPPM’s data. Human red blood cells (RBCs) from three volunteers were assayed at UCD by the delta pH and Ellman methods according to standard procedures. Both assays were carried out at 25 C, and with optimal final substrate concentrations: 10 mM acetylcholine bromide for the delta pH assay and 1 mM acetylthiocholine iodide for the Ellman assay. RBCs were treated with diisopropyl fluorophosphate to generate a dose/response curve of inhibition. This yielded an approximate conversion factor: delta pH = 0.091 Ellman + 0.052 with an r2 of 0.96. This approach permits converting the extensive CRL database of baseline (presumably unexposed) delta pH AChE values into a normal range of Ellman AChE activities, assays used to evaluate occupational exposure to pesticides. The estimated normal 95% range of human AChE for the Ellman assay was 7.12 to 9.10 umol/min/mL with a mean value of 8.23 +/- 0.62 SD umol/min/mL.

Keywords

Blood-analysis; Chemical-analysis; Chemical-factory-workers; Chemical-industry-workers; Chemical-manufacturing-industry; Red-blood-cells; Blood-cells; Chemical-warfare-agents

CAS No.

55-91-4

Publication Date

20050301

Document Type

Abstract; Conference/Symposia Proceedings

Funding Amount

1055222

Funding Type

Cooperative Agreement

Fiscal Year

2005

NTIS Accession No.

NTIS Price

Identifying No.

Cooperative-Agreement-Number-U07-CCU-906162

ISSN

1096-6080

Source Name

The Toxicologist. Society of Toxicology 44th Annual Meeting and ToxExpo, 2005, New Orleans, Louisiana, March 6-10, 2005

State

CA; MD

Performing Organization

University of California - Davis