Cholinesterases sample collection

Peoples, A. Love, R. Cholinesterase activity in blood samples collected from field workers and nonfield workers in California. Toxicology and Applied Pharmacology, 1978, 45,... 

Some significant pitfalls are associated with the measurement of cholinesterase, and these include the timings of sample collection and analysis. The time between blood and tissue sampling and assay should be minimized to prevent further inhibition... 

A comprehensive approach to a states response to a chemical terrorism includes having a plan not only for the crisis and consequence management phases of the incident, but also for all elements required for complete resolution of the event. This may include the necessity to definitively establish whether chemical agents were used, to provide supporting evidence to confirm other analyses, or to provide the forensic proof required to support a criminal prosecution. The collection and analysis of biomedical samples - blood, urine or other tissue from affected humans or animals - is one of the means for providing such information. Although current capabilities such as urinary thiodyglycol excretion or plasma cholinesterase activity can be performed, there is scope for far more sensitive and specific assessments that overcome the limitations of these approaches. 

Rats poisoned by subcutaneous injection of VX at twice the LD50 were kept alive for 20 min with artificial ventilation of the lungs when necessary.At 20 min after the dose of VX, some rats were given intraperitoneal injections of either atropine sulfate (7 mg/kg) or atropine sulfate plus 2-PAM I (17.5 mg/kg). Untreated rats were killed 20 min after injection of VX samples of parotid gland, gastrocnemius muscle, and brain were collected for examination for cholinesterase activity. The treated rats were killed 3 h after treatment. Organ samples were collected and analyzed for cholinesterase activity. Reactivation of cholinesterase was calculated as 100 times the ratio of the difference between cholinesterase activities 3 h after therapy and 20 min after VX to the difference between cholinesterase activities in unpoisoned rats and in poisoned rats 20 min after VX it is shown in Table 3 for the two modes of therapy. 

Several centers have been collecting human samples, including urine, breast milk, peripheral blood, cord blood, meconium, vernix, saliva, hair, and placental tissue (Eskenazi et al. 2005). The samples have been analyzed for the presence of numerous substances, such as mercury, lead, cotinine, pesticides, phthalates, PAHs, PAH-DNA adducts, allergens, endotoxin, antioxidant micronutrients, cytokines, immunoglobulin E, cholinesterase, and thyroid hormones. The centers have also been storing samples for future research purposes (Eskenazi et al. 2005). 

It is unlikely that the unchanged nerve agent would be detected in the blood or tissues of a casualty unless samples were collected very soon after the exposure. A number of methods have been reported for the analysis of nerve agents in blood, for application to animal studies. These involve simple liquid or SPE extraction, for example, using chloroform (sarin, soman) (47), C18 SPE (sarin, soman) l48 49 , ethyl acetate (VX) (50), usually after precipitation of proteins, and analysis by GC/MS or gas chromatography/nitrogen-phosphorus detection (GC/NPD). Sarin bound to cholinesterase and displaced with fluoride ion was extracted by C18 SPE (see Part B) (51). 

TMS derivative by GC/FPD in urine collected over 7 days from casualties of the Tokyo attack (43). Concentrations were not reported but the estimated exposures were 0.13-0.25 mg of sarin in a comatose patient and 0.016-0.032 mg in less severely intoxicated patients. Using LC/MS/MS and a more rigorous method of quantitation, /-PrMPA was detected underivatized in serum at concentrations of 3-136ng/ml in four casualties of the Matsumoto incident and 2-100ng/ml in 13 casualties of the Tokyo attack (59). All samples were taken within 2.5 hours of hospitalization. High levels of /-PrMPA correlated with low levels of butyryl-cholinesterase activity. Other positive analyses associated with these incidents were obtained by identification of inhibited cholinesterase, and are reported in Part B. 

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