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1. Impact of internal standard selection on measurement results for long chain fatty acids in blood

Author

John M. Goodwin, VII, Heather C. Kuiper, Barrett Brister, and Hubert W. Vesper

Subjects
Internal standards, Isotope dilution, Gas chromatography, Mass spectrometry, Fatty acids, Medical technology, R855-855.5
Abstract

Introduction: Internal standards correct for measurement variation due to sample loss. Isotope labeled analytes are ideal internal standards for the measurement of fatty acids in human plasma but are not always readily available. For this reason, quantification of multiple analytes at once is most often done using only a single or few internal standards. The magnitude of the impact this has on method accuracy and precision is not well studied for gas chromatography-mass spectrometry systems. Objective: This study aims to estimate bias and changes in uncertainty associated with using alternative fatty acid isotopologue internal standards for the estimation of similar or dissimilar long chain fatty acids. Method: Using a previously reported method for the quantification of 27 fatty acids in human plasma using 18 internal standards we obtained estimates of bias and uncertainty at up to three levels of fatty acid concentration. Results: With some notable exceptions, method accuracy remained relatively stable when using an alternative internal standard (Median Relative Absolute Percent Bias: 1.76%, Median Spike-Recovery Absolute Percent Bias: 8.82%), with larger changes in method precision (Median Increase in Variance: 141%). Additionally, the degree of difference between analyte and internal standard structure was related to the magnitude of bias and uncertainty of the measurement. Conclusion: The data presented here show that the choice of internal standard used to estimate fatty acid concentration can affect the accuracy and reliability of measurement results and, therefore, needs to be assessed carefully when developing analytical methods for the measurement of fatty acid profiles.Disclaimer: The findings and conclusions in this report are those of the author(s) and do not necessarily represent the official position of the Centers for Disease Control and Prevention/the Agency for Toxic Substances and Disease Registry. Use of trade names is for identification only and does not imply endorsement by the Centers for Disease Control and Prevention, the Public Health Service, and the US Department of Health and Human Services.

Published
2024
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2. Cost assessment of a program for laboratory testing of plasma trans-fatty acids in Thailand

Author

Biplab Kumar Datta, Wichai Aekplakorn, Anchalee Chittamma, Pornchai Meemeaw, Hubert Vesper, Heather C. Kuiper, Lindsay Steele, Laura K. Cobb, Chaoyang Li, Muhammad Jami Husain, Lalida Ketgudee, Deliana Kostova, and Patricia Richter

Subjects
Trans fatty acid, Plasma assay, Cost assessment, Thailand, Public aspects of medicine, RA1-1270
Abstract

Objectives: Intake of trans fatty acids (TFA) increases the risk of cardiovascular disease. Assessment of TFA exposure in the population is key for determining TFA burden and monitoring change over time. One approach for TFA monitoring is measurement of TFA levels in plasma. Understanding costs associated with this approach can facilitate program planning, implementation and scale-up. This report provides an assessment of costs associated with a pilot program to measure plasma TFA levels in Thailand. Study design: Cost analysis in a laboratory facility in Thailand. Methods: We defined three broad cost modules: laboratory, personnel, and facility costs, which were further classified into sub-components and into fixed and variable categories. Costs were estimated based on the number of processed plasma samples (100–2700 in increments of 50) per year over a certain number of years (1–5), in both USD and Thai Baht. Total cost and average costs per sample were estimated across a range of samples processed. Results: The average cost per sample of analyzing 900 samples annually over 5 years was estimated at USD186. Laboratory, personnel, and facility costs constitute 67%, 23%, and 10% of costs, respectively. The breakdown across fixed costs, such as laboratory instruments and personnel, and variable costs, such as chemical supplies, was 60% and 40%, respectively. Average costs decline as more samples are processed: the cost per sample for analyzing 100, 500, 1500, and 2500 samples per year over 5 years is USD1351, USD301, USD195; and USD177, respectively. Conclusions: Laboratory analysis of plasma TFA levels has high potential for economies of scale, encouraging a long-term approach to TFA monitoring initiatives, particularly in countries that already maintain national biometric repositories.

Published
2021
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3. Plasma trans-fatty acid concentrations in fasting adults declined from NHANES 1999–2000 to 2009–2010

Author

Quanhe Yang, Hubert W. Vesper, Namanjeet Ahluwalia, James L. Pirkle, Heather C. Kuiper, Samuel P. Caudill, and David A. Lacher

Subjects
0301 basic medicine, medicine.medical_specialty, National Health and Nutrition Examination Survey, Population, Medicine (miscellaneous), 030204 cardiovascular system & hematology, 03 medical and health sciences, chemistry.chemical_compound, 0302 clinical medicine, Animal science, Internal medicine, Blood plasma, medicine, education, chemistry.chemical_classification, education.field_of_study, 030109 nutrition & dietetics, Nutrition and Dietetics, business.industry, Fatty acid, Elaidic acid, Endocrinology, Linolelaidic acid, chemistry, Blood chemistry, Geometric mean, business
Abstract

Background: The consumption of trans fatty acids (TFAs) is associated with an increased risk of cardiovascular disease, and reducing their consumption is a major public health objective. Food intake studies have provided estimates for TFA concentrations in the US population; however, there is a need for data on TFA blood concentrations in the population.Objective: The objective of this study was to determine plasma TFA concentrations in a nationally representative group of fasted adults in the US population in NHANES samples from 1999-2000 and 2009-2010.Design: Four major TFAs [palmitelaidic acid (C16:1n-7t), trans vaccenic acid (C18:1n-7t), elaidic acid (C18:1n-9t), and linoelaidic acid (C18:2n-6t,9t)] were measured in plasma in 1613 subjects from NHANES 1999-2000 and 2462 subjects from NHANES 2009-2010 by gas chromatography-mass spectrometry. Geometric means and distribution percentiles were calculated for each TFA and their sum by age, sex, and race/ethnicity (non-Hispanic white, non-Hispanic black, Mexican American), and covariate-adjusted geometric means were computed by using a model that included these demographic and other dietary factors, as well as survey year and any significant interaction terms.Results: These nationally representative data for the adult US population show that TFA concentrations were 54% lower in NHANES 2009-2010 than in NHANES 1999-2000. Covariate-adjusted geometric means for the sum of the 4 TFAs were 81.4 μmol/L (95% CI: 77.3, 85.6 μmol/L) and 37.8 μmol/L (95% CI: 36.4, 39.4 μmol/L) in NHANES 1999-2000 and 2009-2010, respectively. Even with the large decline in TFA concentrations, differences between demographic subgroups were comparable in the 2 surveys.Conclusion: The results indicate an overall reduction in TFA concentrations in the US population and provide a valuable baseline to evaluate the impact of the recent regulation categorizing TFAs as food additives.

Published
2017
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4. Ascorbic Acid Promotes Detoxification and Elimination of 4-Hydroxy-2(E)-nonenal in Human Monocytic THP-1 Cells

Author

Ralph L. Reed, Susan Alber, Heather C. Kuiper, Jan F. Stevens, and Cristobal L. Miranda

Subjects
Protein Carbonylation, Apoptosis, Ascorbic Acid, Toxicology, medicine.disease_cause, Article, chemistry.chemical_compound, Dichlorofluorescein, Tumor Cells, Cultured, medicine, Humans, THP1 cell line, chemistry.chemical_classification, Aldehydes, Reactive oxygen species, Leukemia, Vitamin C, Caspase 3, Chemistry, Biological Transport, General Medicine, Glutathione, Fluoresceins, Ascorbic acid, Biochemistry, Inactivation, Metabolic, Oxidative stress
Abstract

4-Hydroxy-2(E)-nonenal (HNE), a reactive aldehyde derived from oxidized lipids, has been implicated in the pathogenesis of cardiovascular and neurological diseases, in part by its ability to induce oxidative stress and by protein carbonylation in target cells. The effects of intracellular ascorbic acid (vitamin C) on HNE-induced cytotoxicity and protein carbonylation were investigated in human THP-1 monocytic leukemia cells. HNE treatment of these cells resulted in apoptosis, necrosis and protein carbonylation. Ascorbic acid accumulated in the cells at concentrations of 6.4 mM or 8.9 mM after treatment with 0.1 mM or 1 mM ascorbate in the medium for 18 h. Pretreatment of cells with 1.0 mM ascorbate decreased HNE-induced formation of reactive oxygen species and formation of protein carbonyls. The protective effects of ascorbate were associated with an increase of the formation of GSH-HNE conjugate and its phase-1 metabolites, measured by LC-MS/MS, and with increased transport of GSH conjugates from the cells into the medium. Ascorbate pretreatment enhanced the efflux of the multidrug resistant protein (MRP) substrate, carboxy-2',7'-dichlorofluorescein (CDF), and it prevented the HNE-induced inhibition of CDF export from THP-1 cells, suggesting that the protective effect of ascorbate against HNE cytotoxicity is through modulation of MRP-mediated transport of GSH-HNE conjugate metabolites. Formation of ascorbate adducts of HNE was observed in the cell exposure experiments, but it represented a minor pathway contributing to the elimination of HNE and to the protective effects of ascorbate.

Published
2009
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5. Mercapturic acid conjugates of 4-hydroxy-2-nonenal and 4-oxo-2-nonenal metabolites are in vivo markers of oxidative stress

Author

Heather C. Kuiper, John D. Sowell, Cristobal L. Miranda, and Jan F. Stevens

Subjects
Linoleic acid, Oxidative phosphorylation, Lipids and Lipoproteins: Metabolism, Regulation, and Signaling, medicine.disease_cause, Biochemistry, Mass Spectrometry, Lipid peroxidation, Linoleic Acid, chemistry.chemical_compound, Lactones, In vivo, medicine, Animals, Mercapturic acid, Molecular Biology, Carbon Tetrachloride, chemistry.chemical_classification, Aldehydes, Cell Biology, Metabolism, Rats, Inbred F344, Acetylcysteine, Rats, Oxidative Stress, chemistry, Models, Chemical, Lipid Peroxidation, Oxidative stress, Lactone, Biomarkers, Chromatography, Liquid
Abstract

Oxidative stress-induced lipid peroxidation leads to the formation of cytotoxic and genotoxic 2-alkenals, such as 4-hydroxy-2-nonenal (HNE) and 4-oxo-2-nonenal (ONE). Lipid-derived reactive aldehydes are subject to phase-2 metabolism and are predominantly found as mercapturic acid (MA) conjugates in urine. This study shows evidence for the in vivo formation of ONE and its phase-1 metabolites, 4-oxo-2-nonen-1-ol (ONO) and 4-oxo-2-nonenoic acid (ONA). We have detected the MA conjugates of HNE, 1,4-dihydroxy-2-nonene (DHN), 4-hydroxy-2-nonenoic acid (HNA), the lactone of HNA, ONE, ONO, and ONA in rat urine by liquid chromatography-tandem mass spectrometry comparison with synthetic standards prepared in our laboratory. CCl4 treatment of rats, a widely accepted animal model of acute oxidative stress, resulted in a significant increase in the urinary levels of DHN-MA, HNA-MA lactone, ONE-MA, and ONA-MA. Our data suggest that conjugates of HNE and ONE metabolites have value as markers of in vivo oxidative stress and lipid peroxidation.

Published
2008

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