Last data update: Apr 22, 2024. (Total: 46599 publications since 2009)
Records 1-22 (of 22 Records) |
Query Trace: Carter MD [original query] |
---|
The Impact of Community-Based Testing Sites and Gift Incentives on COVID-19 Testing Uptake in Maryland, April 29 - May 9, 2021.
Turbyfill C , Thomas I , Agravat N , Prasher JM , Nett RJ , Stevens M , Ricaldi JN , Dunams TM , Brickhouse-Frazier L , Carter MD , Gebru Y , King A , May CS , Miller JD , Oguh C , Pullman A , Roman K , Rose C , Scherr R , Sidibe T , Soelaeman R , Weinstein J , Wilson T , Tran CH . Am J Health Promot 2022 37 (2) 8901171221119796 PURPOSE: Information on incentives for COVID-19 testing is needed to understand effective practices that encourage testing uptake. We describe characteristics of those who received an incentive after performing a rapid antigen test. DESIGN: Cross-sectional descriptive analysis of survey data. SETTING: During April 29-May 9, 2021, COVID-19 rapid antigen testing was offered in 2 Maryland cities. SAMPLE: Convenience sample of 553 adults (≥18 years) who tested and received an incentive; 93% consented to survey. MEASURES: Survey questions assessed reasons for testing, testing history, barriers, and demographics. ANALYSIS: Robust Poisson regressions were used to determine characteristic differences based on testing history and between participants who would re-test in the future without an incentive vs participants who would not. RESULTS: The most common reasons for testing were the desire to be tested (n = 280; 54%) and convenience of location (n = 146; 28%). Those motivated by an incentive to test (n = 110; 21%) were 5.83 times as likely to state they would not test again without an incentive, compared to those with other reasons for testing (95% CI: 2.67-12.72, P < .001). CRITICAL LIMITATIONS: No comparative study group. CONCLUSION: Results indicate internal motivation and convenience were prominent factors supporting testing uptake. Incentives may increase community testing participation, particularly among people who have never tested. Keywords COVID-19, pandemic, incentives, health behavior, community testing. |
The effects of gamma irradiation on chemical biomarker recovery from mixed chemical/biological threat exposure specimens
Isenberg SL , Carter MD , Moon JL , Laughlin S , Petway M , Mojica MA , Rood JE , Gursky AK , Sheppard CI , Bagarozzi DA , Pirkle JL , Johnson RC . J Appl Lab Med 2020 5 (2) 273-280 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. |
Application of the fentanyl analog screening kit toward the identification of emerging synthetic opioids in human plasma and urine by LC-QTOF
Krajewski LC , Swanson KD , Bragg WA , Shaner RL , Seymour C , Carter MD , Hamelin EI , Johnson RC . Toxicol Lett 2020 320 87-94 Human exposures to fentanyl analogs, which significantly contribute to the ongoing U.S. opioid overdose epidemic, can be confirmed through the analysis of clinical samples. Our laboratory has developed and evaluated a qualitative approach coupling liquid chromatography and quadrupole time-of-flight mass spectrometry (LC-QTOF) to address novel fentanyl analogs and related compounds using untargeted, data-dependent acquisition. Compound identification was accomplished by searching against a locally-established mass spectral library of 174 fentanyl analogs and metabolites. Currently, our library can identify 150 fentanyl-related compounds from the Fentanyl Analog Screening (FAS) Kit), plus an additional 25 fentanyl-related compounds from individual purchases. Plasma and urine samples fortified with fentanyl-related compounds were assessed to confirm the capabilities and intended use of this LC-QTOF method. For fentanyl, 8 fentanyl-related compounds and naloxone, lower reportable limits (LRL100), defined as the lowest concentration with 100 % true positive rate (n = 12) within clinical samples, were evaluated and range from 0.5 ng/mL to 5.0 ng/mL for urine and 0.25 ng/mL to 2.5 ng/mL in plasma. The application of this high resolution mass spectrometry (HRMS) method enables the real-time detection of known and emerging synthetic opioids present in clinical samples. |
Designing traceable opioid material kits to improve laboratory testing during the U.S. opioid overdose crisis
Mojica MA , Carter MD , Isenberg SL , Pirkle JL , Hamelin EI , Shaner RL , Seymour C , Sheppard CI , Baldwin GT , Johnson RC . Toxicol Lett 2019 317 53-58 In 2017, the U.S. Department of Health and Human Services and the White House declared a public health emergency to address the opioid crisis (Hargan, 2017). On average, 192 Americans died from drug overdoses each day in 2017; 130 (67%) of those died specifically because of opioids (Scholl et al., 2019). Since 2013, there have been significant increases in overdose deaths involving synthetic opioids - particularly those involving illicitly-manufactured fentanyl. The U.S. Drug Enforcement Administration (DEA) estimates that 75% of all opioid identifications are illicit fentanyls (DEA, 2018b). Laboratories are routinely asked to confirm which fentanyl or other opioids are involved in an overdose or encountered by first responders. It is critical to identify and classify the types of drugs involved in an overdose, how often they are involved, and how that involvement may change over time. Health care providers, public health professionals, and law enforcement officers need to know which opioids are in use to treat, monitor, and investigate fatal and non-fatal overdoses. By knowing which drugs are present, appropriate prevention and response activities can be implemented. Laboratory testing is available for clinically used and widely recognized opioids. However, there has been a rapid expansion in new illicit opioids, particularly fentanyl analogs that may not be addressed by current laboratory capabilities. In order to test for these new opioids, laboratories require reference standards for the large number of possible fentanyls. To address this need, the Centers for Disease Control and Prevention (CDC) developed the Traceable Opioid Material( section sign) Kits product line, which provides over 150 opioid reference standards, including over 100 fentanyl analogs. These kits were designed to dramatically increase laboratory capability to confirm which opioids are on the streets and causing deaths. The kits are free to U.S based laboratories in the public, private, clinical, law enforcement, research, and public health domains. |
Rapid quantification of two chemical nerve agent metabolites in serum
Kammer M , Kussrow A , Carter MD , Isenberg SL , Johnson RC , Batchelor RH , Jackson GW , Bornhop DJ . Biosens Bioelectron 2019 131 119-127 Organophosphorus compounds (OPs) continue to represent a significant chemical threat to humans due to exposures from their use as weapons, their potential storage hazards, and from their continued use agriculturally. Existing methods for detection include ELISA and mass spectrometry. The new approach presented here provides an innovative first step toward a portable OP quantification method that surmounts conventional limitations involving sensitivity, selectivity, complexity, and portability. DNA affinity probes, or aptamers, represent an emerging technology that, when combined with a mix-and-read, free-solution assay (FSA) and a compensated interferometer (CI) can provide a novel alternative to existing OP nerve agent (OPNA) quantification methods. Here it is shown that FSA can be used to rapidly screen prospective aptamers in the biological matrix of interest, allowing the identification of a 'best-in-class' probe. It is also shown that combining aptamers with FSA-CI enables quantification of the OPNA metabolites, Sarin (NATO designation "G-series, B", or GB) and Venomous Agent X (VX) acids, rapidly with high selectivity at detection limits of sub-10pg/mL in 25% serum (by volume in PBS). These results suggest there is potential to directly impact diagnostic specificity and sensitivity of emergency response testing methods by both simplifying sample preparation procedures and making a benchtop reader available for OPNA metabolite quantification. |
Detection of alpha-, beta-, and gamma-amanitin in urine by LC-MS/MS using (15)N10-alpha-amanitin as the internal standard
Abbott NL , Hill KL , Garrett A , Carter MD , Hamelin EI , Johnson RC . Toxicon 2018 152 71-77 The majority of fatalities from poisonous mushroom ingestion are caused by amatoxins. To prevent liver failure or death, it is critical to accurately and rapidly diagnose amatoxin exposure. We have developed an liquid chromatography tandem mass spectrometry method to detect alpha-, beta-, and gamma-amanitin in urine to meet this need. Two internal standard candidates were evaluated, including an isotopically labeled (15)N10-alpha-amanitin and a modified amanitin methionine sulfoxide synthetic peptide. Using the (15)N10-alpha-amanitin internal standard, precision and accuracy of alpha-amanitin in pooled urine was </=5.49% and between 100 and 106%, respectively, with a reportable range from 1-200 ng/mL. beta- and gamma-Amanitin were most accurately quantitated in pooled urine using external calibration, resulting in precision </=17.2% and accuracy between 99 and 105% with calibration ranges from 2.5-200ng/mL and 1.0-200ng/mL, respectively. The presented urinary diagnostic test is the first method to use an isotopically labeled alpha-amanitin with the ability to detect and confirm human exposures to alpha-, beta-, and gamma-amanitin. |
Quantification of hypoglycin A and methylenecyclopropylglycine in human plasma by HPLC-MS/MS
Sanford AA , Isenberg SL , Carter MD , Mojica MA , Mathews TP , Laughlin S , Thomas JD , Pirkle JL , Johnson RC . J Chromatogr B Analyt Technol Biomed Life Sci 2018 1095 112-118 Hypoglycin A (HGA) and methylenecyclopropylglycine (MCPG) are naturally-occurring amino acids known to cause hypoglycemia and encephalopathy. Exposure to one or both toxins through the ingestion of common soapberry (Sapindaceae) fruits are documented in illness outbreaks throughout the world. Jamaican Vomiting Sickness (JVS) and seasonal pasture myopathy (SPM, horses) are linked to HGA exposure from unripe ackee fruit and box elder seeds, respectively. Acute toxic encephalopathy is linked to HGA and MCPG exposures from litchi fruit. HGA and MCPG are found in several fruits within the soapberry family and are known to cause severe hypoglycemia, seizures, and death. HGA has been directly quantified in horse blood in SPM cases and in human gastric juice in JVS cases. This work presents a new diagnostic assay capable of simultaneous quantification of HGA and MCPG in human plasma, and it can be used to detect patients with toxicity from soapberry fruits. The assay presented herein is the first quantitative method for MCPG in blood matrices. |
Quantification of ricinine and abrine in human plasma by HPLC-MS-MS: Biomarkers of exposure to ricin and abrin
Isenberg SL , Carter MD , Miller MA , Noras AI , Mojica MA , Carlsen ST , Bulathsinghala CP , Thomas JD , Johnson RC . J Anal Toxicol 2018 42 (9) 630-636 Ricin and abrin are toxic ribosome-inactivating proteins found in plants. Exposure to these toxins can be detected using the biomarkers ricinine and abrine, which are present in the same plant sources as the toxins. The concentration of the biomarkers in urine and blood will be dependent upon the purification of abrin or ricin, the route of exposure, and the length of time between exposure and sample collection. Here, we present the first diagnostic assay for the simultaneous quantification of both ricinine and abrine in blood matrices. Furthermore, this is the first-ever method for the detection of abrine in blood products. Samples were processed by isotope-dilution, solid-phase extraction, protein precipitation and quantification by HPLC-MS-MS. This analytical method detects abrine from 5.00 to 500 ng/mL and ricinine from 0.300 to 300 ng/mL with coefficients of determination of 0.996 +/- 0.003 and 0.998 +/- 0.002 (n = 22), respectively. Quality control material accuracy was determined to have <10% relative error, and precision was within 19% relative standard deviation. The assay's time-to-first result is three hours including sample preparation. Furthermore, the method was applied for the quantification of ricinine in the blood of a patient who had intentionally ingested castor beans to demonstrate the test was fit-for-purpose. This assay was designed to support the diagnosis of ricin and abrin exposures in public health investigations. |
Quantitative HPLC-MS/MS analysis of toxins in soapberry seeds: Methylenecyclopropylglycine and hypoglycin A
Sanford AA , Isenberg SL , Carter MD , Mojica MA , Mathews TP , Harden LA , Takeoka GR , Thomas JD , Pirkle JL , Johnson RC . Food Chem 2018 264 449-454 Methylenecyclcopropylglycine (MCPG) and hypoglycin A (HGA) are naturally occurring amino acids found in various soapberry (Sapindaceae) fruits. These toxins have been linked to illnesses worldwide and were recently implicated in Asian outbreaks of acute hypoglycemic encephalopathy. In a previous joint agricultural and public health investigation, we developed an analytical method capable of evaluating MCPG and HGA concentrations in soapberry fruit arils as well as a clinical method for the urinary metabolites of the toxins. Since the initial soapberry method only analyzed the aril portion of the fruit, we present here the extension of the method to include the fruit seed matrix. This work is the first method to quantitate both MCPG and HGA concentrations in the seeds of soapberry fruit, including those collected during a public health investigation. Further, this is the first quantitation of HGA in litchi seeds as well as both toxins in mamoncillo and longan seeds. |
Structural Characterization and Absolute Quantification of Microcystin Peptides Using Collision-Induced and Ultraviolet Photo-Dissociation Tandem Mass Spectrometry.
Attard TJ , Carter MD , Fang M , Johnson RC , Reid GE . J Am Soc Mass Spectrom 2018 29 (9) 1812-1825 Microcystin (MC) peptides produced by cyanobacteria pose a hepatotoxic threat to human health upon ingestion from contaminated drinking water. While rapid MC identification and quantification in contaminated body fluids or tissue samples is important for patient treatment and outcomes, conventional immunoassay-based measurement strategies typically lack the specificity required for unambiguous determination of specific MC variants, whose toxicity can significantly vary depending on their structures. Furthermore, the unambiguous identification and accurate quantitation of MC variants using tandem mass spectrometry (MS/MS)-based methods can be limited due to a current lack of appropriate stable isotope-labeled internal standards. To address these limitations, we have systematically examined here the sequence and charge state dependence to the formation and absolute abundance of both "global" and "variant-specific" product ions from representative MC-LR, MC-YR, MC-RR, and MC-LA peptides, using higher-energy collisional dissociation (HCD)-MS/MS, ion-trap collision-induced dissociation (CID)-MS/MS and CID-MS(3), and 193 nm ultraviolet photodissociation (UPVD)-MS/MS. HCD-MS/MS was found to provide the greatest detection sensitivity for both global and variant-specific product ions in each of the MC variants, except for MC-YR where a variant-specific product uniquely formed via UPVD-MS/MS was observed with the greatest absolute abundance. A simple methodology for the preparation and characterization of (18)O-stable isotope-labeled MC reference materials for use as internal standards was also developed. Finally, we have demonstrated the applicability of the methods developed herein for absolute quantification of MC-LR present in human urine samples, using capillary scale liquid chromatography coupled with ultra-high resolution / accurate mass spectrometry and HCD-MS/MS. Graphical abstract . |
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. |
High-confidence qualitative identification of organophosphorus nerve agent adducts to human butyrylcholinesterase
Mathews TP , Carter MD , Johnson D , Isenberg SL , Graham LA , Thomas JD , Johnson RC . Anal Chem 2017 89 (3) 1955-1964 In this study, a data-dependent, high-resolution tandem mass spectrometry (ddHRMS/MS) method capable of detecting all organophosphorus nerve agent (OPNA) adducts to human butyrylcholinesterase (BChE) was developed. After an exposure event, immunoprecipitation from blood with a BChE-specific antibody and digestion with pepsin produces a nine amino acid peptide containing the OPNA adduct. Signature product ions of this peptic BChE nonapeptide (FGES*AGAAS) offer a route to broadly screen for OPNA exposure. Taking this approach on an HRMS instrument identifies biomarkers, including unknowns, with high mass accuracy. Using a set of pooled human sera exposed to OPNAs as quality control (QC) materials, the developed method successfully identified precursor ions with <1 ppm and tied them to signature product ions with <5 ppm deviation from their chemical formulas. This high mass accuracy data from precursor and product ions, collected over 23 independent immunoprecipitation preparations, established method operating limits. QC data and experiments with 14 synthetic reference peptides indicated that reliable qualitative identification of biomarkers was possible for analytes >15 ng/mL. The developed method was applied to a convenience set of 96 unexposed serum samples and a blinded set of 80 samples treated with OPNAs. OPNA biomarkers were not observed in convenience set samples and no false positive or negative identifications were observed in blinded samples. All biomarkers in the blinded serum set >15 ng/mL were correctly identified. For the first time, this study reports a ddHRMS/MS method capable of complementing existing quantitative methodologies and suitable for identifying exposure to unknown organophosphorus agents. |
Association of acute toxic encephalopathy with litchi consumption in an outbreak in Muzaffarpur, India, 2014: a case-control study
Shrivastava A , Kumar A , Thomas JD , Laserson KF , Bhushan G , Carter MD , Chhabra M , Mittal V , Khare S , Sejvar JJ , Dwivedi M , Isenberg SL , Johnson R , Pirkle JL , Sharer JD , Hall PL , Yadav R , Velayudhan A , Papanna M , Singh P , Somashekar D , Pradhan A , Goel K , Pandey R , Kumar M , Kumar S , Chakrabarti A , Sivaperumal P , Kumar AR , Schier JG , Chang A , Graham LA , Mathews TP , Johnson D , Valentin L , Caldwell KL , Jarrett JM , Harden LA , Takeoka GR , Tong S , Queen K , Paden C , Whitney A , Haberling DL , Singh R , Singh RS , Earhart KC , Dhariwal AC , Chauhan LS , Venkatesh S , Srikantiah P . Lancet Glob Health 2017 5 (4) e458-e466 BACKGROUND: Outbreaks of unexplained illness frequently remain under-investigated. In India, outbreaks of an acute neurological illness with high mortality among children occur annually in Muzaffarpur, the country's largest litchi cultivation region. In 2014, we aimed to investigate the cause and risk factors for this illness. METHODS: In this hospital-based surveillance and nested age-matched case-control study, we did laboratory investigations to assess potential infectious and non-infectious causes of this acute neurological illness. Cases were children aged 15 years or younger who were admitted to two hospitals in Muzaffarpur with new-onset seizures or altered sensorium. Age-matched controls were residents of Muzaffarpur who were admitted to the same two hospitals for a non-neurologic illness within seven days of the date of admission of the case. Clinical specimens (blood, cerebrospinal fluid, and urine) and environmental specimens (litchis) were tested for evidence of infectious pathogens, pesticides, toxic metals, and other non-infectious causes, including presence of hypoglycin A or methylenecyclopropylglycine (MCPG), naturally-occurring fruit-based toxins that cause hypoglycaemia and metabolic derangement. Matched and unmatched (controlling for age) bivariate analyses were done and risk factors for illness were expressed as matched odds ratios and odds ratios (unmatched analyses). FINDINGS: Between May 26, and July 17, 2014, 390 patients meeting the case definition were admitted to the two referral hospitals in Muzaffarpur, of whom 122 (31%) died. On admission, 204 (62%) of 327 had blood glucose concentration of 70 mg/dL or less. 104 cases were compared with 104 age-matched hospital controls. Litchi consumption (matched odds ratio [mOR] 9.6 [95% CI 3.6 - 24]) and absence of an evening meal (2.2 [1.2-4.3]) in the 24 h preceding illness onset were associated with illness. The absence of an evening meal significantly modified the effect of eating litchis on illness (odds ratio [OR] 7.8 [95% CI 3.3-18.8], without evening meal; OR 3.6 [1.1-11.1] with an evening meal). Tests for infectious agents and pesticides were negative. Metabolites of hypoglycin A, MCPG, or both were detected in 48 [66%] of 73 urine specimens from case-patients and none from 15 controls; 72 (90%) of 80 case-patient specimens had abnormal plasma acylcarnitine profiles, consistent with severe disruption of fatty acid metabolism. In 36 litchi arils tested from Muzaffarpur, hypoglycin A concentrations ranged from 12.4 mug/g to 152.0 mug/g and MCPG ranged from 44.9 mug/g to 220.0 mug/g. INTERPRETATION: Our investigation suggests an outbreak of acute encephalopathy in Muzaffarpur associated with both hypoglycin A and MCPG toxicity. To prevent illness and reduce mortality in the region, we recommended minimising litchi consumption, ensuring receipt of an evening meal and implementing rapid glucose correction for suspected illness. A comprehensive investigative approach in Muzaffarpur led to timely public health recommendations, underscoring the importance of using systematic methods in other unexplained illness outbreaks. FUNDING: US Centers for Disease Control and Prevention. |
A high-throughput UHPLC-MS/MS method for the quantification of five aged butyrylcholinesterase biomarkers from human exposure to organophosphorus nerve agents
Graham LA , Johnson D , Carter MD , Stout EG , Erol HA , Isenberg SL , Mathews TP , Thomas JD , Johnson RC . Biomed Chromatogr 2016 31 (4) Organophosphorus nerve agents (OPNAs) are toxic compounds that are classified as prohibited Schedule 1 chemical weapons. In the body, OPNAs bind to butyrylcholinesterase (BChE) to form nerve agent adducts (OPNA-BChE). OPNA-BChE adducts can provide a reliable, long-term protein biomarker for assessing human exposure. A major challenge facing OPNA-BChE detection is hydrolysis (aging), which can continue to occur after a clinical specimen has been collected. During aging, the o-alkyl phosphoester bond hydrolyzes, and the specific identity of the nerve agent is lost. To better identify OPNA exposure events, a high throughput method for the detection of five aged OPNA-BChE adducts was developed. This is the first diagnostic panel to allow for the simultaneous quantification of any Chemical Weapons Convention Schedule 1 OPNA by measuring the aged adducts methyl phosphonate (MeP-BChE), ethyl phosphonate (EtP-BChE), propyl phosphonate (PrP-BChE), ethyl phosphoryl (ExP-BChE), phosphoryl (P-BChE), and unadducted BChE. The calibration range for all analytes is 2.00 - 250. ng/mL, which is consistent with similar methodologies used to detect unaged OPNA-BChE adducts. Each analytical run is three minutes making the time to first unknown results, including calibration curve and quality controls, less than one hour. Analysis of commercially purchased individual serum samples demonstrated no potential interferences with detection of aged OPNA-BChE adducts, and quantitative measurements of endogenous levels of BChE were similar to those previously reported in other OPNA-BChE adduct assays. |
Quantification of toxins in soapberry (Sapindaceae) arils: hypoglycin A and methylenecyclopropylglycine
Isenberg SL , Carter MD , Hayes SR , Graham LA , Johnson D , Mathews TP , Harden LA , Takeoka GR , Thomas JD , Pirkle JL , Johnson RC . J Agric Food Chem 2016 64 (27) 5607-13 Methylenecyclopropylglycine (MCPG) and hypoglycin A (HGA) are naturally occurring amino acids found in some soapberry fruits. Fatalities have been reported worldwide as a result of HGA ingestion, and exposure to MCPG has been implicated recently in the Asian outbreaks of hypoglycemic encephalopathy. In response to an outbreak linked to soapberry ingestion, the authors developed the first method to simultaneously quantify MCPG and HGA in soapberry fruits from 1 to 10000 ppm of both toxins in dried fruit aril. Further, this is the first report of HGA in litchi, longan, and mamoncillo arils. This method is presented to specifically address the laboratory needs of public-health investigators in the hypoglycemic encephalitis outbreaks linked to soapberry fruit ingestion. |
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. |
Quantification of metabolites for assessing human exposure to soapberry toxins hypoglycin A and methylenecyclopropylglycine
Isenberg SL , Carter MD , Graham LA , Mathews TP , Johnson D , Thomas JD , Pirkle JL , Johnson RC . Chem Res Toxicol 2015 28 (9) 1753-9 Ingestion of soapberry fruit toxins hypoglycin A and methylenecyclopropylglycine has been linked to public health challenges worldwide. In 1976, over 100 years after Jamaican vomiting sickness (JVS) was first reported, the cause of JVS was linked to the ingestion of the toxin hypoglycin A produced by ackee fruit. A structural analogue of hypoglycin A, methylenecyclopropylglycine (MCPG), was implicated as the cause of an acute encephalitis syndrome (AES). Much of the evidence linking hypoglycin A and MCPG to these diseases has been largely circumstantial due to the lack of an analytical method for specific metabolites. This study presents an analytical approach to identify and quantify specific urine metabolites for exposure to hypoglycin A and MCPG. The metabolites are excreted in urine as glycine adducts methylenecyclopropylacetyl-glycine (MCPA-Gly) and methylenecyclopropylformyl-glycine (MCPF-Gly). These metabolites were processed by isotope dilution, separated by reverse-phase liquid chromatography, and monitored by electrospray ionization tandem mass spectrometry. The analytical response ratio was linearly proportional to the concentration of MCPF-Gly and MCPA-Gly in urine from 0.10 to 20 mug/mL with a correlation coefficient of r > 0.99. The assay demonstrated accuracy ≥80% and precision ≤20% RSD across the calibration range. This method has been applied to assess exposure to hypoglycin A and MCPG as part of a larger public health initiative and was used to provide the first reported identification of MCPF-Gly and MCPA-Gly in human urine. |
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. |
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. |
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. |
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. |
- Page last reviewed:Feb 1, 2024
- Page last updated:Apr 22, 2024
- Content source:
- Powered by CDC PHGKB Infrastructure