Use of reactivation techniques for the differential diagnosis of organophosphorus and carbamate pesticide poisoning in birds

Acetylcholinesterase Inhibition in the Threeridge Mussel (Amblema plicata) by Chlorpyrifos: Implications for Biomonitoring

“…In this study, the microplate assay technique was used based on the modi"ed method of Ellman et al (1961)*presumably a procedure with reduced variation. The chemical reactivation technique, another procedure that has been used to assess OP exposure in birds and "shes (Martin et al, 1981;Fleming and Bradbury, 1981), o!ers an alternative to potentially reduce variation in AChE measurements with freshwater mussels. In that assay, AChE activity is reactivated by the nucleophilic reagent, pyridine-2-aldoxime methiodide (2-PAM).…”

Avian Mortality Events in the United States Caused by Anticholinesterase Pesticides: A Retrospective Summary of National Wildlife Health Center Records from 1980 to 2000

“…In the final mortality event, a great-tailed grackle (Quiscalus mexicanus) had a brain ChE activity of 17.4 mol/min/g, increasing to 29.2 mol/ min/g after 18 h of incubation at 37°C. Because we found 9.48 ppm wet weight of carbofuran in the great-tailed grackle gastrointestinal contents, we concluded that brain ChE had likely experienced some degree of spontaneous reactivation prior to its initial measurement (Martin et al 1981;Grue et al 1991).…”

“…If the ChE activity of the sample was two standard deviations below the mean normal activity, the brain homogenate was incubated at 37°C for 18 h and reanalyzed to determine if enzyme reactivation occurred. Reactivation, or a return toward normal brain ChE activity, is characteristic of CBs but not OPs (Martin et al 1981;Smith et al 1995).…”

“…In all but four of the confirmed poisoning events, both of these criteria were met through analyses performed on the same bird or birds; in four events, measurement of brain ChE activity and chemical analysis of gut contents were performed on samples from different individuals of the same species. In 14 carcasses in 14 instances where carbofuran (n ϭ 13) or aldicarb (n ϭ 1) was identified in gut contents, the brain ChE activity was not inhibited by 50%, presumably because of spontaneous reactivation (Martin et al 1981;Grue et al 1991) or rapid death before significant levels of CB reached brain tissue (Grue et al 1991). Suspected anticholinesterase poisoning events were those in which either the brain ChE activity was depressed by Ն50% or a specific OP or CB compound was identified in a gastrointestinal sample.…”

An evaluation of avian impact assessment techniques following broad‐scale forest insecticide sprays

“…The cholinesterase enzyme inhibition assay, for example, is useful in the context of organophosphate and carbamate pesticides and can even be made to differentiate between the two [35]. However, the technique is not useful with newer classes of insecticides such as the synthetic pyrethroids.…”