Last data update: Apr 29, 2024. (Total: 46658 publications since 2009)
Records 1-17 (of 17 Records) |
Query Trace: Crow BS[original query] |
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Recapitulation of human pathophysiology and identification of forensic biomarkers in a translational model of chlorine inhalation injury
Achanta S , Gentile MA , Albert CJ , Schulte KA , Pantazides BG , Crow BS , Quinones-Gonzalez J , Perez JW , Ford DA , Patel RP , Blake TA , Gunn MD , Jordt SE . Am J Physiol Lung Cell Mol Physiol 2024 Chlorine gas (Cl(2)) has been repeatedly used as a chemical weapon, first in World War I and most recently in Syria. Life-threatening Cl(2) exposures frequently occur in domestic and occupational environments, and in transportation accidents. Modeling the human etiology of Cl(2)-induced acute lung injury (ALI), forensic biomarkers, and targeted countermeasures development have been hampered by inadequate large animal models. The objective of this study was to develop a translational model of Cl(2)-induced ALI in swine to understand toxico-pathophysiology and is suitable for screening potential medical countermeasures, and identify biomarkers useful for forensic analysis. Specific pathogen-free Yorkshire swine (30-40 kg) of either sex were exposed to Cl(2) (≤ 240 ppm for 1 h) or filtered air under anesthesia and controlled mechanical ventilation. Exposure to Cl(2) resulted in severe hypoxia and hypoxemia, increased airway resistance and peak inspiratory pressure, and decreased dynamic lung compliance. Cl(2) exposure resulted in increased total leucocyte and neutrophil counts in bronchoalveolar lavage fluid (BALF), vascular leakage, and pulmonary edema compared to the air-exposed group. The model recapitulated all three key histopathological features of human ALI, such as neutrophilic alveolitis, deposition of hyaline membranes, and formation of microthrombi. Free and lipid-bound 2‑chlorofatty acids and chlorotyrosine-modified proteins (3-chloro-L-tyrosine and 3,5-dichloro-L-tyrosine) were detected in plasma and lung tissue after Cl(2)‑exposure. In this study, we developed a translational swine model that recapitulates key features of human Cl(2) inhalation injury and is suitable for testing medical countermeasures, and validated chlorinated fatty acids and protein adducts as biomarkers of Cl(2) inhalation. |
Establishing population values for chlorine exposure in the United States (2015-2016) Using 2 chlorine biomarkers, 3-chlorotyrosine and 3,5-dichlorotyrosine
Boles SL , Pantazides BG , Perez JW , Sternberg MR , Crow BS , Blake TA . J Appl Lab Med 2024 BACKGROUND: In the United States, 12 million short tons of chlorine are manufactured and transported each year. Due to the volume of this volatile chemical, large- and small-scale chemical exposures occur frequently. To diagnose and treat potentially exposed individuals, reference range values for confirmatory biomarkers are required to differentiate between normal and abnormal exposure levels. METHODS: Serum surplus samples (n = 1780) from the National Health and Nutrition Examination Survey (NHANES) 2015-2016 were measured for 2 chlorine biomarkers, 3-chlorotyrosine (Cl-Tyr) and 3,5-dichlorotyrosine (Cl2-Tyr), by liquid chromatography coupled to a triple quadrupole mass spectrometer. We evaluated demographic factors associated with elevated biomarker levels. RESULTS: Participant samples were analyzed for the chlorine biomarkers Cl-Tyr and Cl2-Tyr. In the unweighted analysis of these samples, 1349 (75.8%) were under the limit of detection (< LOD) of 2.50 ng/mL for Cl-Tyr and 1773 (99.6%) were < LOD for Cl2-Tyr. Samples within the method reportable range were 2.50 to 35.6 ng/mL for Cl-Tyr and 2.69 to 11.2 ng/mL for Cl2-Tyr. Since only 7 of the 1780 participants had detectable Cl2-Tyr, statistical analysis was limited to Cl-Tyr. Of the demographic characteristics examined, age, body mass index (BMI), estimated glomerular filtration rate (eGFR), and sex exhibited statistically significant differences in the weighted prevalence of detectable Cl-Tyr. CONCLUSIONS: This is the first reported set of Cl-Tyr and Cl2-Tyr population values for the United States. This population range coupled with NHANES demographic information could help healthcare professionals distinguish between normal and abnormal chlorine biomarker levels in an emergency. With this information, an inference could be made when determining acute chlorine exposure in individuals. |
Recapitulation of Human Pathophysiology and Identification of Forensic Biomarkers in a Translational Swine Model of Chlorine Inhalation Injury (preprint)
Achanta S , Gentile MA , Albert CJ , Schulte KA , Pantazides BG , Crow BS , Quinones-Gonzalez J , Perez JW , Ford DA , Patel RP , Blake TA , Gunn MD , Jordt SE . bioRxiv 2022 10 Rationale: Chlorine gas (Cl<inf>2</inf>) has been repeatedly used as a chemical weapon, first in World War I and most recently in Syria. Life-threatening Cl<inf>2</inf> exposures frequently occur in domestic and occupational environments, and in transportation accidents. There is a knowledge gap in large animal models of Cl<inf>2</inf>-induced acute lung injury (ALI) required to accurately model human etiology and for the development of targeted countermeasures Objective: To develop a translational model of Cl<inf>2</inf>-induced ALI in swine to study toxicopathophysiology and identify biomarkers useful for forensic analysis. Method(s): Specific pathogen-free Yorkshire swine (30-40 kg) of either sex were exposed to Cl<inf>2</inf> gas (<= 240 ppm for 1 h) or filtered air under anesthesia and controlled mechanical ventilation. Result(s): Exposure to Cl<inf>2</inf> resulted in severe hypoxia and hypoxemia, increased airway resistance and peak inspiratory pressure, and decreased dynamic lung compliance. Chlorine exposure resulted in increased total BALF and neutrophil counts, vascular leakage, and edema compared to the control group. The model recapitulated all three key histopathological features of human ALI, such as neutrophilic alveolitis, deposition of hyaline membranes, and formation of microthrombi. Free and lipid-bound 2-chlorofatty acids and chlorotyrosine-modified proteins (3-chloro-L-tyrosine and 3,5-dichloro-L-tyrosine) were detected in plasma and lung after Cl<inf>2</inf>-exposure. Conclusion(s): The translational model developed in this study replicates key features of humans exposed to Cl<inf>2</inf> and is suitable to test medical countermeasures. Specific biomarkers of Cl<inf>2</inf> exposure have been identified in plasma and lung tissue samples. Copyright The copyright holder for this preprint is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license. |
Development of a clinical assay to measure chlorinated tyrosine in hair and tissue samples using a mouse chlorine inhalation exposure model
Pantazides BG , Crow BS , Quiñones-González J , Perez JW , Harvilchuck JA , Wallery JJ , Hu TC , Thomas JD , Johnson RC , Blake TA . Anal Bioanal Chem 2021 413 (6) 1765-1776 Chlorine is a toxic industrial chemical with a history of use as a chemical weapon. Chlorine is also produced, stored, and transported in bulk making it a high-priority pulmonary threat in the USA. Due to the high reactivity of chlorine, few biomarkers exist to identify exposure in clinical and environmental samples. Our laboratory evaluates acute chlorine exposure in clinical samples by measuring 3-chlorotyrosine (Cl-Tyr) and 3,5-dichlorotyrosine (Cl(2)-Tyr) using liquid chromatography tandem mass spectrometry (LC-MS/MS). Individuals can have elevated biomarker levels due to their environment and chronic health conditions, but levels are significantly lower in individuals exposed to chlorine. Historically these biomarkers have been evaluated in serum, plasma, blood, and bronchoalveolar lavage (BAL) fluid. We report the expansion into hair and lung tissue samples using our newly developed tissue homogenization protocol which fits seamlessly with our current chlorinated tyrosine quantitative assay. Furthermore, we have updated the chlorinated tyrosine assay to improve throughput and ruggedness and reduce sample volume requirements. The improved assay was used to measure chlorinated tyrosine levels in 198 mice exposed to either chlorine gas or air. From this animal study, we compared Cl-Tyr and Cl(2)-Tyr levels among three matrices (i.e., lung, hair, and blood) and found that hair had the most abundant chlorine exposure biomarkers. Furthermore, we captured the first timeline of each analyte in the lung, hair, and blood samples. In mice exposed to chlorine gas, both Cl-Tyr and Cl(2)-Tyr were present in blood and lung samples up to 24 h and up to 30 days in hair samples. |
A quantitative method to detect human exposure to sulfur and nitrogen mustards via protein adducts
Pantazides BG , Quinones-Gonzalez J , Rivera Nazario DM , Crow BS , Perez JW , Blake TA , Johnson RC . J Chromatogr B Analyt Technol Biomed Life Sci 2019 1121 9-17 Sulfur and nitrogen mustards are internationally banned vesicants listed as Schedule 1 chemical agents in the Chemical Weapons Convention. These compounds are highly reactive electrophiles that form stable adducts to a variety of available amino acid residues on proteins upon exposure. We present a quantitative exposure assay that simultaneously measures agent specific protein adducts to cysteine for sulfur mustard (HD) and three nitrogen mustards (HN1, HN2, and HN3). Proteinase K was added to a serum or plasma sample to digest protein adducts and form the target analyte, the blister agent bound to the tripeptide cysteine-proline-phenylalanine (CPF). The mustard adducted-tripeptide was purified by solid phase extraction and analyzed using isotope dilution LC-MS/MS. Product ion structures were identified using high-resolution product ion scan data for HD-CPF, HN1-CPF, HN2-CPF, and HN3-CPF. Thorough matrix comparison, analyte recovery, ruggedness, and stability studies were incorporated during method validation to produce a robust method. The method demonstrated long term-stability, precision (RSD<15%), and intra- and inter-day accuracies>85% across the reportable range of 3.00-200ng/mL for each analyte. Compared to previously published assays, this method quantitates both sulfur and nitrogen mustard exposure biomarkers, requires only 10muL of sample volume, and can use either a liquid sample or dried sample spot. |
Supplemental learning in the laboratory: An innovative approach for evaluating knowledge and method transfer
Carter MD , Pierce SS , Dukes AD , Brown RH , Crow BS , Shaner RL , Heidari L , Isenberg SL , Perez JW , Graham LA , Thomas JD , Johnson RC , Gerdon AE . J Chem Educ 2017 94 (8) 1094-1097 The Multi-Rule Quality Control System (MRQCS) is a tool currently employed by the Centers for Disease Control and Prevention (CDC) to evaluate and compare laboratory performance. We have applied the MRQCS to a comparison of instructor-led and computer-led prelaboratory instruction for a supplemental learning experiment. Students in general chemistry and analytical chemistry from both two- and four-year institutions performed two laboratory experiments as part of their normal laboratory curriculum. The first laboratory experiment was a foundational learning experiment in which all of the students were introduced to the Beer-Lambert law and spectrophotometric light absorbance measurements. The foundational learning experiment was instructor-led only, and participant performance was evaluated against a mean characterized value. The second laboratory experiment was a supplemental learning experiment in which students were asked to build upon the methodology they learned in the foundational learning experiment and apply it to a different analyte. The instruction type was varied randomly into two delivery modes, with participants receiving either instructor-led or computer-led prelaboratory instruction. The MRQCS was applied, and it was determined that there was no statistical difference between the quality control passing rates of the participants receiving instructor-led instruction and those receiving computer-led instruction. These findings demonstrate the successful application of the MRQCS to evaluate knowledge and technology transfer. |
Bridging the Gap between Sample Collection and Laboratory Analysis: Using Dried Blood Spots to Identify Human Exposure to Chemical Agents
Hamelin EI , Blake TA , Perez JW , Crow BS , Shaner RL , Coleman RM , Johnson RC . Proc SPIE Int Soc Opt Eng 2016 98630 98630p-98630p9 Public health response to large scale chemical emergencies presents logistical challenges for sample collection, transport, and analysis. Diagnostic methods used to identify and determine exposure to chemical warfare agents, toxins, and poisons traditionally involve blood collection by phlebotomists, cold transport of biomedical samples, and costly sample preparation techniques. Use of dried blood spots, which consist of dried blood on an FDA-approved substrate, can increase analyte stability, decrease infection hazard for those handling samples, greatly reduce the cost of shipping/storing samples by removing the need for refrigeration and cold chain transportation, and be self-prepared by potentially exposed individuals using a simple finger prick and blood spot compatible paper. Our laboratory has developed clinical assays to detect human exposures to nerve agents through the analysis of specific protein adducts and metabolites, for which a simple extraction from a dried blood spot is sufficient for removing matrix interferents and attaining sensitivities on par with traditional sampling methods. The use of dried blood spots can bridge the gap between the laboratory and the field allowing for large scale sample collection with minimal impact on hospital resources while maintaining sensitivity, specificity, traceability, and quality requirements for both clinical and forensic applications. |
Simultaneous measurement of 3-chlorotyrosine and 3,5-dichlorotyrosine in whole blood, serum and plasma by isotope dilution HPLC-MS-MS
Crow BS , Quinones-Gonzalez J , Pantazides BG , Perez JW , Winkeljohn WR , Garton JW , Thomas JD , Blake TA , Johnson RC . J Anal Toxicol 2016 40 (4) 264-71 Chlorine is a public health concern and potential threat due to its high reactivity, ease and scale of production, widespread industrial use, bulk transportation, massive stockpiles and history as a chemical weapon. This work describes a new, sensitive and rapid stable isotope dilution method for the retrospective detection and quantitation of two chlorine adducts. The biomarkers 3-chlorotyrosine (Cl-Tyr) and 3,5-dichlorotyrosine (Cl2-Tyr) were isolated from the pronase digest of chlorine exposed whole blood, serum or plasma by solid-phase extraction (SPE), separated by reversed-phase HPLC and detected by tandem mass spectrometry (MS-MS). The calibration range is 2.50-1,000 ng/mL (R2 ≥ 0.998) with a lowest reportable limit (LRL) of 2.50 ng/mL for both analytes, an accuracy of ≥93% and an LOD of 0.443 ng/mL for Cl-Tyr and 0.396 ng/mL for Cl2-Tyr. Inter- and intra-day precision of quality control samples had coefficients of variation of ≤10% and ≤7.0%, respectively. Blood and serum samples from 200 healthy individuals and 175 individuals with chronic inflammatory disease were analyzed using this method to assess background levels of chlorinated tyrosine adducts. Results from patients with no known inflammatory disease history (healthy) showed baseline levels of <LRL-4.26 ng/mL Cl-Tyr and <LRL Cl2-Tyr. Patients with inflammatory disease had baseline levels of <LRL-15.4 ng/mL Cl-Tyr and <LRL-5.22 ng/mL Cl2-Tyr. Blood exposed to 2.02 ppm chlorine gas for 15 min produced 941 ng/mL Cl-Tyr and 223 ng/mL Cl2-Tyr. This high-throughput method has been developed and analytically validated for the diagnosis of human exposure to chlorine. |
Quantification of hydrazine in human urine by HPLC-MS-MS
Isenberg SL , Carter MD , Crow BS , Graham LA , Johnson D , Beninato N , Steele K , Thomas JD , Johnson RC . J Anal Toxicol 2016 40 (4) 248-54 Currently used on F-16 fighter jets and some space shuttles, hydrazine could be released at toxic levels to humans as a result of an accidental leakage or spill. Lower-level exposures occur in industrial workers or as a result of the use of some pharmaceuticals. A method was developed for the quantitation of hydrazine in human urine and can be extended by dilution with water to cover at least six orders of magnitude, allowing measurement at all clinically significant levels of potential exposure. Urine samples were processed by isotope dilution, filtered, derivatized and then quantified by HPLC-MS-MS. The analytical response ratio was linearly proportional to the urine concentration of hydrazine from 0.0493 to 12.3 ng/mL, with an average correlation coefficient R of 0.9985. Inter-run accuracy for 21 runs, expressed as percent relative error (% RE), was ≤14%, and the corresponding precision, expressed as percent relative standard deviation (% RSD), was ≤15%. Because this method can provide a quantitative measurement of clinical samples over six orders of magnitude, it can be used to monitor trace amounts of hydrazine exposure as well as industrial and environmental exposure levels. |
Quantitation of ortho-cresyl phosphate adducts to butyrylcholinesterase in human serum by immunomagnetic-UHPLC-MS/MS
Johnson D , Carter MD , Crow BS , Isenberg SL , Graham LA , Erol HA , Watson CM , Pantazides BG , van der Schans MJ , Langenberg JP , Noort D , Blake TA , Thomas JD , Johnson RC . J Mass Spectrom 2015 50 (4) 683-92 Tri-ortho-cresyl phosphate (ToCP) is an anti-wear, flame retardant additive used in industrial lubricants, hydraulic fluids and gasoline. The neurotoxic effects of ToCP arise from the liver-activated metabolite 2-(o-cresyl)-4H-1,3,2-benzodioxaphosphoran-2-one (cresyl saligenin phosphate or CBDP), which inhibits esterase enzymes including butyrylcholinesterase (BChE). Following BChE adduction, CBDP undergoes hydrolysis to form the aged adduct ortho-cresyl phosphoserine (oCP-BChE), thus providing a biomarker of CBDP exposure. Previous studies have identified ToCP in aircraft cabin and cockpit air, but assessing human exposure has been hampered by the lack of a laboratory assay to confirm exposure. This work presents the development of an immunomagnetic-UHPLC-MS/MS method for the quantitation of unadducted BChE and the long-term CBDP biomarker, oCP-BChE, in human serum. The method has a reportable range from 2.0 ng/ml to 150 ng/ml, which is consistent with the sensitivity of methods used to detect organophosphorus nerve agent protein adducts. The assay demonstrated high intraday and interday accuracy (≥85%) and precision (RSD ≤ 15%) across the calibration range. The method was developed for future analyses of potential human exposure to CBDP. Analysis of human serum inhibited in vitro with CBDP demonstrated that the oCP-BChE adduct was stable for at least 72 h at 4, 22 and 37 degrees C. Compared to a previously reported assay, this method requires 75% less sample volume, reduces analysis time by a factor of 20 and demonstrates a threefold improvement in sensitivity. |
Simplified method for quantifying sulfur mustard adducts to blood proteins by ultrahigh pressure liquid chromatography-isotope dilution tandem mass spectrometry
Pantazides BG , Crow BS , Garton JW , Quinones-Gonzalez JA , Blake TA , Thomas JD , Johnson RC . Chem Res Toxicol 2015 28 (2) 256-61 Sulfur mustard binds to reactive cysteine residues, forming a stable sulfur-hydroxyethylthioethyl [S-HETE] adduct that can be used as a long-term biomarker of sulfur mustard exposure in humans. The digestion of sulfur mustard-exposed blood samples with proteinase K following total protein precipitation with acetone produces the tripeptide biomarker [S-HETE]-Cys-Pro-Phe. The adducted tripeptide is purified by solid phase extraction, separated by ultrahigh pressure liquid chromatography, and detected by isotope dilution tandem mass spectrometry. This approach was thoroughly validated and characterized in our laboratory. The average interday relative standard deviation was ≤9.49%, and the range of accuracy was between 96.1 and 109% over a concentration range of 3.00 to 250. ng/mL with a calculated limit of detection of 1.74 ng/mL. A full 96-well plate can be processed and analyzed in 8 h, which is 5 times faster than our previous 96-well plate method and only requires 50 muL of serum, plasma, or whole blood. Extensive ruggedness and stability studies and matrix comparisons were conducted to create a robust, easily transferrable method. As a result, a simple and high-throughput method has been developed and validated for the quantitation of sulfur mustard blood protein adducts in low volume blood specimens which should be readily adaptable for quantifying human exposures to other alkylating agents. |
Simultaneous measurement of tabun, sarin, soman, cyclosarin, VR, VX, and VM adducts to tyrosine in blood products by isotope dilution UHPLC-MS/MS
Crow BS , Pantazides BG , Quinones-Gonzalez J , Garton JW , Carter MD , Perez JW , Watson CM , Tomcik DJ , Crenshaw MD , Brewer BN , Riches JR , Stubbs SJ , Read RW , Evans RA , Thomas JD , Blake TA , Johnson RC . Anal Chem 2014 86 (20) 10397-405 This work describes a new specific, sensitive, and rapid stable isotope dilution method for the simultaneous detection of the organophosphorus nerve agents (OPNAs) tabun (GA), sarin (GB), soman (GD), cyclosarin (GF), VR, VX, and VM adducts to tyrosine (Tyr). Serum, plasma, and lysed whole blood samples (50 muL) were prepared by protein precipitation followed by digestion with Pronase. Specific Tyr adducts were isolated from the digest by a single solid phase extraction (SPE) step, and the analytes were separated by reversed-phase ultra high performance liquid chromatography (UHPLC) gradient elution in less than 2 min. Detection was performed on a triple quadrupole tandem mass spectrometer using time-triggered selected reaction monitoring (SRM) in positive electrospray ionization (ESI) mode. The calibration range was characterized from 0.100-50.0 ng/mL for GB- and VR-Tyr and 0.250-50.0 ng/mL for GA-, GD-, GF-, and VX/VM-Tyr (R2 ≥ 0.995). Inter- and intra-assay precision had coefficients of variation of ≤17 and ≤10%, respectively, and the measured concentration accuracies of spiked samples were within 15% of the targeted value for multiple spiking levels. The limit of detection was calculated to be 0.097, 0.027, 0.018, 0.074, 0.023, and 0.083 ng/mL for GA-, GB-, GD-, GF-, VR-, and VX/VM-Tyr, respectively. A convenience set of 96 serum samples with no known nerve agent exposure was screened and revealed no baseline values or potential interferences. This method provides a simple and highly specific diagnostic tool that may extend the time postevent that a confirmation of nerve agent exposure can be made with confidence. |
Quantitation of five organophosphorus nerve agent metabolites in serum using hydrophilic interaction liquid chromatography and tandem mass spectrometry
Hamelin EI , Schulze ND , Shaner RL , Coleman RM , Lawrence RJ , Crow BS , Jakubowski EM , Johnson RC . Anal Bioanal Chem 2014 406 (21) 5195-202 Although nerve agent use is prohibited, concerns remain for human exposure to nerve agents during decommissioning, research, and warfare. Exposure can be detected through the analysis of hydrolysis products in urine as well as blood. An analytical method to detect exposure to five nerve agents, including VX, VR (Russian VX), GB (sarin), GD (soman), and GF (cyclosarin), through the analysis of the hydrolysis products, which are the primary metabolites, in serum has been developed and characterized. This method uses solid-phase extraction coupled with high-performance liquid chromatography for separation and isotopic dilution tandem mass spectrometry for detection. An uncommon buffer of ammonium fluoride was used to enhance ionization and improve sensitivity when coupled with hydrophilic interaction liquid chromatography resulting in detection limits from 0.3 to 0.5 ng/mL. The assessment of two quality control samples demonstrated high accuracy (101-105 %) and high precision (5-8 %) for the detection of these five nerve agent hydrolysis products in serum. |
An enhanced butyrylcholinesterase method to measure organophosphorus nerve agent exposure in humans
Pantazides BG , Watson CM , Carter MD , Crow BS , Perez JW , Blake TA , Thomas JD , Johnson RC . Anal Bioanal Chem 2014 406 (21) 5187-94 Organophosphorus nerve agent (OPNA) adducts to butyrylcholinesterase (BChE) can be used to confirm exposure in humans. A highly accurate method to detect G- and V-series OPNA adducts to BChE in 75 muL of filtered blood, serum, or plasma has been developed using immunomagnetic separation (IMS) coupled with liquid chromatography tandem mass spectrometry (LC-MS/MS). The reported IMS method captures > 88 % of the BChE in a specimen and corrects for matrix effects on peptide calibrators. The optimized method has been used to quantify baseline BChE levels (unadducted and OPNA-adducted) in a matched-set of serum, plasma, and whole blood (later processed in-house for plasma content) from 192 unexposed individuals to determine the interchangeability of the tested matrices. The results of these measurements demonstrate the ability to accurately measure BChE regardless of the format of the blood specimen received. Criteria for accepting or denying specimens were established through a series of sample stability and processing experiments. The results of these efforts are an optimized and rugged method that is transferrable to other laboratories and an increased understanding of the BChE biomarker in matrix. |
Direct quantitation of methyl phosphonate adducts to human serum butyrylcholinesterase by immunomagnetic-UHPLC-MS/MS
Carter MD , Crow BS , Pantazides BG , Watson CM , Thomas JD , Blake TA , Johnson RC . Anal Chem 2013 85 (22) 11106-11 Hydrolysis of G- and V-series organophosphorus nerve agents (OPNAs) containing a phosphorus-methyl bond yields a methylphosphonic acid (MeP) product when adducted to human butyrylcholinesterase (BChE). The MeP adduct is considered a sign of "aging" and results in loss of the o-alkyl identifier specific to each nerve agent. After aging has occurred, common therapeutics such as oximes cannot reactivate the cholinesterase enzyme and relieve cholinergic inhibition. Until now, a direct, quantitative method for determination of the MeP adduct to BChE was unavailable. Aged adducts in serum samples were processed by immunomagnetic separation of BChE by antibody conjugated bead, isotope-dilution, pepsin digestion, followed by UHPLC separation and detection by conventional electrospray ionization-tandem mass spectrometry (ESI-MS/MS). Ions were detected in selected reaction monitoring (SRM) mode, and transition m/z 874.3 → 778.3 was used for quantitation. The analytical response ratio was linearly proportional to the serum concentration of MeP-adducted peptide (MeP-P) over the nominal concentration range of 2.0-250 ng/mL, with a coefficient of determination of R(2) ≥ 0.997. Intrarun accuracy, expressed as %Relative Error (%RE), was ≤13.5%, 16.3%, and 3.20% at 2.0, 16, and 250 ng/mL, respectively; the corresponding precision expressed as %RSD was ≤11.9%, 6.15%, and 3.39%. Interday %RSD was ≤7.13%, 5.69%, and 1.91%. Recovery of MeP-P from serum was ≥68% across the validated concentration range, and contributions from matrix effects were minimal. The method provides a direct, quantitative measurement of MeP-P found in clinical samples suspected of nerve agent exposure and subjected to such post-sampling stresses as elevated temperature and extended shipping. |
An enhanced throughput method for quantification of sulfur mustard adducts to human serum albumin via isotope dilution tandem mass spectrometry
Andacht TM , Pantazides BG , Crow BS , Fidder A , Noort D , Thomas JD , Blake TA , Johnson RC . J Anal Toxicol 2013 38 (1) 8-15 Here, we report an enhanced throughput method for the diagnosis of human exposure to sulfur mustard. A hydroxyethylthioethyl (HETE) ester-adducted tripeptide, produced by pronase digestion of human serum albumin, was selected as the quantitative exposure biomarker. Cibacron Blue enrichment was developed from an established cartridge method into a 96-well plate format, increasing throughput and ruggedness. This new method decreased sample volume 2.5-fold. Addition of a precipitation and solid-phase extraction concentration step increased the sensitivity of the method. With the conversion to a 96-well plate and optimization of chromatography, the method resulted in a 3-fold decrease in analysis time. Inclusion of a confirmation ion has increased specificity. The method was found to be linear between 0.050 and 50 microM sulfur mustard exposure with a precision for both quality control samples of ≤6.5% relative standard deviation and an accuracy of >96%. The limit of detection (3So) was calculated to be approximately 0.0048 microM, an exposure value similar to that of the HETE-albumin adduct method first described by Noort and co-workers (Noort et al., 1999; Noort el al., 2004) which used protein precipitation to isolate albumin. A convenience set of 124 plasma samples from healthy unexposed individuals was analyzed using this method to assess background levels of exposure to sulfur mustard; no positive results were detected. |
Profiling cholinesterase adduction: a high-throughput prioritization method for organophosphate exposure samples
Carter MD , Crow BS , Pantazides BG , Watson CM , Decastro BR , Thomas JD , Blake TA , Johnson RC . J Biomol Screen 2013 19 (2) 325-30 A high-throughput prioritization method was developed for use with a validated confirmatory method detecting organophosphorus nerve agent exposure by immunomagnetic separation high-performance liquid chromatography tandem mass spectrometry. A ballistic gradient was incorporated into this analytical method to profile unadducted butyrylcholinesterase (BChE) in clinical samples. With Zhang et al.'s Z' factor of 0.88 +/- 0.01 (SD) of control analytes and Z factor of 0.25 +/- 0.06 (SD) of serum samples, the assay is rated an "excellent assay" for the synthetic peptide controls used and a "double assay" when used to prioritize clinical samples. Hits, defined as samples containing BChE Ser-198 adducts or no BChE present, were analyzed in a confirmatory method for identification and quantitation of the BChE adduct, if present. The ability to prioritize samples by highest exposure for confirmatory analysis is of particular importance in an exposure to cholinesterase inhibitors such as organophosphorus nerve agents, in which a large number of clinical samples may be collected. In an initial blind screen, 67 of 70 samples were accurately identified, giving an assay accuracy of 96%, and it yielded no false-negatives. The method is the first to provide a high-throughput prioritization assay for profiling adduction of Ser-198 BChE in clinical samples. |
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