Last data update: Jun 03, 2024. (Total: 46935 publications since 2009)
Records 1-8 (of 8 Records) |
Query Trace: Graham LA [original query] |
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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. |
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