The Effects of Gamma Irradiation on Chemical Biomarker Recovery from Mixed Chemical/Biological Threat Exposure Specimens

Abstract

Background Irradiative sterilization of clinical specimens prior to chemical laboratory testing provides a way to not only sterilize pathogens and ensure laboratorian safety but also preserve sample volume and maintain compatibility with quantitative chemical diagnostic protocols. Since the compatibility of clinical biomarkers with gamma irradiation is not well characterized, a subset of diagnostic biomarkers ranging in molecular size, concentration, and clinical matrix was analyzed to determine recovery following gamma irradiation. Methods Sample irradiation of previously characterized quality control materials (QCs) at 5 Mrad was carried out at the Gamma Cell Irradiation Facility at the Centers for Disease Control and Prevention (CDC) in Atlanta, GA. Following irradiation, the QCs were analyzed alongside non-irradiated QCs to determine analyte recovery between dosed and control samples. Results Biomarkers for exposure to abrin, ricin, and organophosphorus nerve agents (OPNAs) were analyzed for their stability following gamma irradiation. The diagnostic biomarkers included adducts to butyrylcholinesterase, abrine, and ricinine, respectively, and were recovered at over 90% of their initial concentration. Conclusions The results from this pilot study support the implementation of an irradiative sterilization protocol for possible mixed-exposure samples containing both chemical and biological threat agents (mixed CBTs). Furthermore, irradiative sterilization significantly reduces a laboratorian’s risk of infection from exposure to an infectious agent without compromising chemical diagnostic testing integrity, particularly for diagnostic assays in which the chemical analyte has been shown to be fully conserved following a 5 Mrad irradiative dose.

Gamma‐irradiation of common biological samples for stable carbon and nitrogen isotope and elemental analyses

“…While we consider the γ-irradiation treatment as a potential reason for these differences, there may be additional secondary factors that can exacerbate these changes, e.g., sample preservationwhere irradiation results in more thorough sterilisation than air drying alone. 27 Bacterial decomposition of analytical samples can lead to stable isotope fractionation and isotopic enrichment in heavier isotopes in both marine producers 28 and decomposing animal tissues. 29 The mechanism underpinning such changes is worthy of further investigation, as it has been shown to affect both nitrogen and carbon to a similar degree (i.e., see changes between fresh and decomposed mangrove leaves 28 ).…”