Last data update: Sep 16, 2024. (Total: 47680 publications since 2009)
Records 1-8 (of 8 Records) |
Query Trace: Myers GL [original query] |
---|
Large-scale scientific study led by a professional organization during the COVID-19 pandemic: Operations, best practices, and lessons learned
Ondracek CR , Melanson SEF , Doan L , Schulz KM , Kleinman S , Zhao Z , Kumanovics A , Wu AHB , Wiencek J , Meng QH , Apple FS , Koch D , Vesper H , Pokuah F , Bryksin J , Myers GL , Christenson RH , Zhang YV . J Appl Lab Med 2023 In 2021, the Association for Diagnostics & Laboratory Medicine (ADLM) (formerly the American Association for Clinical Chemistry [AACC]) developed a scientific study that aimed to contribute to the understanding of SARS-CoV-2 immunity during the evolving course of the pandemic. This study was led by a group of expert member volunteers and resulted in survey data from 975 individuals and blood collection from 698 of those participants. This paper describes the formulation and execution of this large-scale scientific study, encompassing best practices and insights gained throughout the endeavor. |
An updated protocol based on CLSI document C37 for preparation of off-the-clot serum from individual units for use alone or to prepare commutable pooled serum reference materials
Danilenko U , Vesper HW , Myers GL , Clapshaw PA , Camara JE , Miller WG . Clin Chem Lab Med 2019 58 (3) 368-374 Manufacturers of in vitro diagnostic medical devices, clinical laboratories, research laboratories and calibration laboratories require commutable reference materials that can be used in the calibration hierarchies of medical laboratory measurement procedures used for human specimens to establish metrological traceability to higher order reference systems. Commutable materials are also useful in external quality assessment surveys. In order to achieve these goals, matrix-based reference materials with long-term stability, appropriate measurand concentrations and commutability with individual human specimens are required. The Clinical and Laboratory Standards Institute (CLSI) guideline C37-A (now archived) provided guidance to prepare commutable pooled serum reference materials for use in the calibration hierarchies of cholesterol measurement procedures. Experience using the C37-A guideline has identified a number of technical enhancements as well as applications to measurands other than cholesterol. This experience is incorporated into this updated protocol to ensure the procedure will continue to meet the needs of the medical laboratory. The updated protocol describes a procedure for preparing frozen human serum units or pools with minimal matrix alterations that are likely to be commutable with individual human serum samples. The protocol provides step-by-step guidance for the planning phase, collection of individual serum units, processing the units, qualifying the units for use in a pool and frozen storage of aliquots of pooled sera to manufacture frozen serum pools. Guidance on how to perform quality control of the final product and suggestions on documentation are also provided. |
Current practices and challenges in the standardization and harmonization of clinical laboratory tests
Vesper HW , Myers GL , Miller WG . Am J Clin Nutr 2016 104 Suppl 3 907S-12S Effective patient care, clinical research, and public health efforts require comparability of laboratory results independent of time, place, and measurement procedure. Comparability is achieved by establishing metrological traceability, which ensures that measurement procedures measure the same quantity and that the calibration of measurement procedures is traceable to a common reference system consisting of reference methods and materials. Whereas standardization ensures traceability to the International System of Units, harmonization ensures traceability to a reference system agreed on by convention. This article provides an overview of standardization and harmonization with an emphasis on commutability as an important variable that affects testing accuracy. Commutability of reference materials is required to ensure that traceability is established appropriately and that laboratory results are comparable. The use of noncommutable reference materials leads to inaccurate results. Whereas procedures and protocols for standardizing measurements are established and have been successfully applied in efforts such as the Hormones Standardization Program of the CDC, harmonization activities require new, more complex procedures and approaches. The American Association for Clinical Chemistry, together with its domestic and international partners, formed the International Consortium for Harmonization of Clinical Laboratory Results to coordinate harmonization efforts. Reference systems, as well as procedures and protocols to establish traceability of clinical laboratory tests, have been established and continue to be developed by national and international groups and organizations. Serum tests of thyroid function, including those for the thyroid hormones thyroxine and triiodothyronine, are among the clinical procedures for which standardization efforts are well under way. Approaches to the harmonization of measurement procedures for serum concentrations of thyroid-stimulating hormone are likewise under development. |
Non-HDL cholesterol shows improved accuracy for cardiovascular risk score classification compared to direct or calculated LDL cholesterol in a dyslipidemic population
van Deventer HE , Miller WG , Myers GL , Sakurabayashi I , Bachmann LM , Caudill SP , Dziekonski A , Edwards S , Kimberly MM , Korzun WJ , Leary ET , Nakajima K , Nakamura M , Shamburek RD , Vetrovec GW , Warnick GR , Remaley AT . Clin Chem 2011 57 (3) 490-501 BACKGROUND: Our objective was to evaluate the accuracy of cardiovascular disease (CVD) risk score classification by direct LDL cholesterol (dLDL-C), calculated LDL cholesterol (cLDL-C), and non-HDL cholesterol (non-HDL-C) compared to classification by reference measurement procedures (RMPs) performed at the CDC. METHODS: We examined 175 individuals, including 138 with CVD or conditions that may affect LDL-C measurement. dLDL-C measurements were performed using Denka, Kyowa, Sekisui, Serotec, Sysmex, UMA, and Wako reagents. cLDL-C was calculated by the Friedewald equation, using each manufacturer's direct HDL-C assay measurements, and total cholesterol and triglyceride measurements by Roche and Siemens (Advia) assays, respectively. RESULTS: For participants with triglycerides <2.26 mmol/L (<200 mg/dL), the overall misclassification rate for the CVD risk score ranged from 5% to 17% for cLDL-C methods and 8% to 26% for dLDL-C methods when compared to the RMP. Only Wako dLDL-C had fewer misclassifications than its corresponding cLDL-C method (8% vs 17%; P < 0.05). Non-HDL-C assays misclassified fewer patients than dLDL-C for 4 of 8 methods (P < 0.05). For participants with triglycerides ≥2.26 mmol/L (≥200 mg/dL) and <4.52 mmol/L (<400 mg/dL), dLDL-C methods, in general, performed better than cLDL-C methods, and non-HDL-C methods showed better correspondence to the RMP for CVD risk score than either dLDL-C or cLDL-C methods. CONCLUSIONS: Except for hypertriglyceridemic individuals, 7 of 8 dLDL-C methods failed to show improved CVD risk score classification over the corresponding cLDL-C methods. Non-HDL-C showed overall the best concordance with the RMP for CVD risk score classification of both normal and hypertriglyceridemic individuals. |
Proposed serum cholesterol reference measurement procedure by gas chromatography-isotope dilution mass spectrometry
Edwards SH , Kimberly MM , Pyatt SD , Stribling SL , Dobbin KD , Myers GL . Clin Chem 2011 57 (4) 614-22 BACKGROUND: Our purpose was to establish a mass spectrometry reference measurement procedure (RMP) for cholesterol to use in the CDC's standardization programs. We explored a gas chromatography-isotope dilution mass spectrometry (GC-IDMS) procedure using a multilevel standard calibration curve to quantify samples with varying cholesterol concentrations. METHODS: We calibrated the mass spectrometry instrument by isotope dilution with a pure primary standard reference material and an isotopically enriched cholesterol analog as the internal standard (IS). We diluted the serum samples with Tris-HCl buffer (pH 7.4, 0.05 mol/L, 0.25% Triton X-100) before analysis. We used 17 serum pools, 10 native samples, and 2 standard reference materials (SRMs). We compared the GC-IDMS measurements with the CDC's modified Abell-Levy-Brodie-Kendall (AK) RMP measurements and assessed method accuracy by analyzing 2 SRMs. We evaluated the procedure for lack of interference by analyzing serum spiked with a mixture of 7 sterols. RESULTS: The mean percent bias between the AK and the GC-IDMS RMP was 1.6% for all samples examined. The mean percent bias from NIST's RMP was 0.5% for the SRMs. The total %CVs for SRM 1951b levels I and II were 0.61 and 0.73%, respectively. We found that none of the sterols investigated interfered with the cholesterol measurement. CONCLUSIONS: The low imprecision, linear response, lack of interferences, and acceptable bias vs the NIST primary RMP qualifies this procedure as an RMP for determining serum cholesterol. The CDC will adopt and implement this GC-IDMS procedure for cholesterol standardization. |
Validation of CKD and related conditions in existing data sets: a systematic review
Grams ME , Plantinga LC , Hedgeman E , Saran R , Myers GL , Williams DE , Powe NR . Am J Kidney Dis 2011 57 (1) 44-54 BACKGROUND: Accurate classification of individuals with kidney disease is vital to research and public health efforts aimed at improving health outcomes. Our objective is to identify and synthesize published literature evaluating the accuracy of existing data sources related to kidney disease. STUDY DESIGN: A systematic review of studies seeking to validate the accuracy of the underlying data relevant to kidney disease. SETTING & POPULATION: US-based and international studies covering a wide range of both outpatient and inpatient study populations. SELECTION CRITERIA FOR STUDIES: Any English-language study investigating the prevalence or cause of kidney disease, existence of comorbid conditions, or cause of death in patients with chronic kidney disease (CKD). All definitions and stages of CKD, including end-stage renal disease (ESRD), were accepted. INDEX TESTS: Presence of a kidney disease-related variable in existing data sets, including administrative data sets and disease registries. REFERENCE TESTS: Presence of a kidney disease-related variable defined using laboratory criteria or medical record review. RESULTS: 30 studies were identified. Most studies investigated the accuracy of kidney disease reporting, comparing coded renal disease with that defined using estimated glomerular filtration rate. The sensitivity of coded renal disease varied widely (0.08-0.83). Specificity was higher, with all studies reporting values ≥0.90. Studies evaluating the cause of CKD, comorbid conditions, and cause of death in patients with CKD used ESRD or transplant populations exclusively, and accuracy was highly variable compared with ESRD registry data. LIMITATIONS: Only English-language studies were evaluated. CONCLUSIONS: Given the heterogeneous results of validation studies, a variety of attributes of existing data sources, including the accuracy of individual data items within these sources, should be considered carefully before use in research, quality improvement, and public health efforts. |
Seven direct methods for measuring HDL and LDL cholesterol compared with ultracentrifugation reference measurement procedures
Miller WG , Myers GL , Sakurabayashi I , Bachmann LM , Caudill SP , Dziekonski A , Edwards S , Kimberly MM , Korzun WJ , Leary ET , Nakajima K , Nakamura M , Nilsson G , Shamburek RD , Vetrovec GW , Warnick GR , Remaley AT . Clin Chem 2010 56 (6) 977-86 BACKGROUND: Methods from 7 manufacturers and 1 distributor for directly measuring HDL cholesterol (C) and LDL-C were evaluated for imprecision, trueness, total error, and specificity in nonfrozen serum samples. METHODS: We performed each direct method according to the manufacturer's instructions, using a Roche/Hitachi 917 analyzer, and compared the results with those obtained with reference measurement procedures for HDL-C and LDL-C. Imprecision was estimated for 35 runs performed with frozen pooled serum specimens and triplicate measurements on each individual sample. Sera from 37 individuals without disease and 138 with disease (primarily dyslipidemic and cardiovascular) were measured by each method. Trueness and total error were evaluated from the difference between the direct methods and reference measurement procedures. Specificity was evaluated from the dispersion in differences observed. RESULTS: Imprecision data based on 4 frozen serum pools showed total CVs <3.7% for HDL-C and <4.4% for LDL-C. Bias for the nondiseased group ranged from -5.4% to 4.8% for HDL-C and from -6.8% to 1.1% for LDL-C, and for the diseased group from -8.6% to 8.8% for HDL-C and from -11.8% to 4.1% for LDL-C. Total error for the nondiseased group ranged from -13.4% to 13.6% for HDL-C and from -13.3% to 13.5% for LDL-C, and for the diseased group from -19.8% to 36.3% for HDL-C and from -26.6% to 31.9% for LDL-C. CONCLUSIONS: Six of 8 HDL-C and 5 of 8 LDL-C direct methods met the National Cholesterol Education Program total error goals for nondiseased individuals. All the methods failed to meet these goals for diseased individuals, however, because of lack of specificity toward abnormal lipoproteins. |
Exposure of the U.S. population to acrylamide in the National Health and Nutrition Examination Survey 2003-2004
Vesper HW , Caudill SP , Osterloh JD , Meyers T , Scott D , Myers GL . Environ Health Perspect 2010 118 (2) 278-83 BACKGROUND: The lifelong exposure of the population to acrylamide has raised concerns about the possible health effects of the chemical. Data on the extent of exposure to acrylamide and its primary metabolite, glycidamide, are needed to aid in the assessment of potential health effects. OBJECTIVES: The aim of this study was to assess human exposure to acrylamide and glycidamide in the general U.S. population through the measurement of hemoglobin adducts of acrylamide (HbAA) and glycidamide (HbGA). METHODS: HbAA and HbGA were measured in 7,166 subjects from the National Health and Nutrition Examination Survey. Stratified HbAA and HbGA data were reported by sex, age groups, race/ethnicity (Mexican American, non-Hispanic black, non-Hispanic white), and smoking status based on serum cotinine levels. Covariate-adjusted geometric means for each demographic group were calculated using multiple regression analysis. RESULTS: HbAA and HbGA levels ranged from 3 to 910 and from 4 to 756 pmol/g hemoglobin, respectively, with smokers having the highest levels overall. Tobacco smoke exposure in nonsmokers had a small but significant effect on HbAA and HbGA levels. Adjusted geometric mean levels for children 311 years of age were higher than for adults ≥ 60 years of age [mean (95% confidence interval): HbAA, 54.5 (49.151.5) and HbGA, 73.9 (71.376.6) vs. HbAA, 46.2 (44.348.2) and HbGA, 41.8 (38.745.2)]. Levels were highest in Mexican Americans [HbAA: 54.8 (51.957.8), HbGA: 57.9 (53.762.5)], whereas non-Hispanic blacks had the lowest HbGA levels [43.5 (41.145.9)]. CONCLUSIONS: U.S. population levels of acrylamide and glycidamide adducts are described. The high variability among individuals but modest differences between population subgroups suggest that sex, age, and race/ethnicity do not strongly affect acrylamide exposure. Adduct concentration data can be used to estimate relative exposure and to validate intake estimates. EDITOR'S SUMMARY: Human exposure to acrylamide, a neurotoxin and suspected human carcinogen, occurs via dietary sources, tobacco smoke, and occupational production or use. Carcinogenic effects are attributed to DNA adducts formed with the phase I metabolite glycidamide, and body burdens and risks may be partly determined by factors that influence acrylamide metabolism, including genetic variants and factors that induce metabolism gene expression (e.g., medications and alcohol). Vesper et al. (p. 278) measured hemoglobin adducts of acrylamide (HbAA) and glycidamide (HbGA) in blood samples from 7,166 participants in the National Health and Nutrition Examination Survey, and estimated HbGA:HbAA ratios to assess variation in metabolic conversion. The authors report that smokers had the highest adjusted geometric mean levels of HbAA and HbGA and that adduct levels in nonsmokers were associated with tobacco smoke exposure (based on serum cotinine levels). In addition, adduct levels and HbGA:HbAA ratios were higher in children 311 years of age than in adults ≥ 60 years of age, and in Mexican Americans compared with other participants. The authors note that differences among population subgroups were modest relative to differences among individuals within subgroups, and suggest that factors other than sex, age, and race/ethnicity may be primarily responsible for variation in acrylamide exposure and metabolism. |
- Page last reviewed:Feb 1, 2024
- Page last updated:Sep 16, 2024
- Content source:
- Powered by CDC PHGKB Infrastructure