The Experts below are selected from a list of 69 Experts worldwide ranked by ideXlab platform
Koulman Albert - One of the best experts on this subject based on the ideXlab platform.
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Erythrocyte transketolase activity coefficient (ETKAC) assay protocol for the assessment of thiamine (vitamin B1) status
'Organisation for Economic Co-Operation and Development (OECD)', 2020Co-Authors: Jones Kerry, Parkington Damon, Cox Lorna, Koulman AlbertAbstract:Vitamin B1 (thiamine) is an essential nutrient that acts as a cofactor for a number of metabolic processes, particularly in energy metabolism. Symptoms of classic thiamine deficiency are recognised as beriberi, although clinical symptoms are non-specific and recognition of sub-clinical deficiency is difficult. Therefore, reliable Biomarkers of thiamine status are required. Thiamine diphosphate (ThDP) is a cofactor for transketolase including erythrocyte transketolase (ETK).The ETK activity assay as an indirect, functional marker of thiamine status, has been used for over 50 years. The ETK activity assay provides a sensitive and specific Biomarker of thiamine status, however, there is a lack of consensus over the cut-offs for deficiency, partly due to a lack of assay harmonization. Here, we provide a step-by-step protocol for the measurement of ETK activity and calculation of the ETK activity coefficient (ETKAC), including detailed explanations of equipment and chemicals required and guidance for quality control procedures. Harmonization of protocol will provide the basis for the development of internationally recognized cut-offs for thiamine insufficiency. The establishment of quality control materials and a quality assurance scheme are recommended to provide reliability. This will ensure the ETK activity assay remains an important method for the assessment of thiamine status.KSJ, DAP and AK are supported by the National Institute for Health Research (NIHR) Cambridge Biomedical Research Centre (IS-BRC-1215- 20014). The NIHR Cambridge Biomedical Research Centre is a partnership between Cambridge University Hospitals NHS Foundation Trust and the University of Cambridge, funded by the NIHR. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care. LJC has an advisory role at the NIHR BRC Nutritional Biomarker Laboratory
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Erythrocyte transketolase activity coefficient (ETKAC) assay protocol for the assessment of thiamine status.
'Organisation for Economic Co-Operation and Development (OECD)', 2020Co-Authors: Jones Kerry, Parkington Damon, Cox, Lorna J, Koulman AlbertAbstract:Vitamin B1 (thiamine) is an essential nutrient that acts as a cofactor for a number of metabolic processes, particularly in energy metabolism. Symptoms of classic thiamine deficiency are recognised as beriberi, although clinical symptoms are non-specific and recognition of sub-clinical deficiency is difficult. Therefore, reliable Biomarkers of thiamine status are required. Thiamine diphosphate (ThDP) is a cofactor for transketolase including erythrocyte transketolase (ETK).The ETK activity assay as an indirect, functional marker of thiamine status, has been used for over 50 years. The ETK activity assay provides a sensitive and specific Biomarker of thiamine status, however, there is a lack of consensus over the cut-offs for deficiency, partly due to a lack of assay harmonization. Here, we provide a step-by-step protocol for the measurement of ETK activity and calculation of the ETK activity coefficient (ETKAC), including detailed explanations of equipment and chemicals required and guidance for quality control procedures. Harmonization of protocol will provide the basis for the development of internationally recognized cut-offs for thiamine insufficiency. The establishment of quality control materials and a quality assurance scheme are recommended to provide reliability. This will ensure the ETK activity assay remains an important method for the assessment of thiamine status.KSJ, DAP and AK are supported by the National Institute for Health Research (NIHR) Cambridge Biomedical Research Centre (IS-BRC-1215- 20014). The NIHR Cambridge Biomedical Research Centre is a partnership between Cambridge University Hospitals NHS Foundation Trust and the University of Cambridge, funded by the NIHR. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care. LJC has an advisory role at the NIHR BRC Nutritional Biomarker Laboratory
Francisca A De Leeuw - One of the best experts on this subject based on the ideXlab platform.
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associations between nutrient intake and corresponding Nutritional Biomarker levels in blood in a memory clinic cohort the nudad project
Journal of the American Medical Directors Association, 2020Co-Authors: Francisca A De Leeuw, Philip Scheltens, Ellen G H M Van Den Heuvel, Ondine Van De Rest, Astrid S Doorduijn, Jay L P Fieldhouse, Marian A E De Van Der Schueren, Marjolein Visser, Charlotte E Teunissen, Maartje I KesterAbstract:Diet is a promising intervention target to prevent or slow Alzheimer's disease (AD). Early (predementia) stages of AD offer a unique opportunity for dietary interventions. Nutritional assessment methods to estimate nutrient intake have, however, not been validated in clinical populations. Hence, we assessed the association between nutrient intake assessed by food frequency questionnaire (FFQ) and nutrient status measured by Nutritional Biomarkers in blood in a clinical sample of controls, mild cognitive impairment (MCI), and patients with AD.
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specific Nutritional Biomarker profiles in mild cognitive impairment and subjective cognitive decline are associated with clinical progression the nudad project
Journal of the American Medical Directors Association, 2020Co-Authors: Francisca A De Leeuw, Wiesje M Van Der Flier, Betty M Tijms, Philip Scheltens, Vera M Mendes, Bruno Manadas, Jorgen Bierau, Nick Van Wijk, Ellen G H M Van Den Heuvel, Hasan M MohajeriAbstract:Abstract Objectives Nutritional insufficiencies have been associated with cognitive impairment. Understanding whether Nutritional Biomarker levels are associated with clinical progression could help to design dietary intervention trials. This longitudinal study examined a panel of Nutritional Biomarkers in relation to clinical progression in patients with subjective cognitive decline (SCD) or mild cognitive impairment (MCI). Design, setting and participants We included 299 patients without dementia (n = 149 SCD; age 61 ± 10 years, female 44%, n = 150 MCI; age 66 ± 8 years, female 38%). Median (interquartile range) follow-up was 3 (2-5) years. Methods We measured 28 Nutritional Biomarkers in blood and 5 in cerebrospinal fluid (CSF), associated with 3 Alzheimer's disease pathologic processes: vascular change (lipids), synaptic dysfunction (homocysteine-related metabolites), and oxidative stress (minerals and vitamins). Nutritional Biomarker associations with clinical progression to MCI/dementia and cognitive decline based on the Mini-Mental State Examination score were evaluated using Cox proportional hazard models and linear mixed models. We used partial least squares Cox models (PLS-Cox) to examine Nutritional Biomarker profiles associated with clinical progression. Results In the total group, high high-density lipoprotein (HDL) levels were associated with clinical progression and cognitive decline. In SCD, high folate and low bilirubin levels were associated with cognitive decline. In MCI, low CSF S-adenosylmethionine (SAM) and high theobromine were associated with clinical progression to dementia and high HDL, cholesterol, iron, and 1,25(OH)2 vitamin D were associated with cognitive decline. PLS-Cox showed 1 profile for SCD, characterized by high betaine and folate and low zinc associated with clinical progression. In MCI, a profile with high theobromine and HDL and low triglycerides and a second profile with high plasma SAM and low cholesterol were associated with risk of dementia. Conclusion and Implications High HDL was most consistently associated with clinical progression. Moreover, different Nutritional Biomarker profiles for SCD and MCI showed promising associations with clinical progression. Future dietary (intervention) studies could use Nutritional Biomarker profiles to select patients, taking into account the disease stage.
Marian L Neuhouser - One of the best experts on this subject based on the ideXlab platform.
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can dietary self reports usefully complement blood concentrations for estimation of micronutrient intake and chronic disease associations
The American Journal of Clinical Nutrition, 2020Co-Authors: Marian L Neuhouser, Lesley F Tinker, Ross L Prentice, Mary Pettinger, Ying Huang, Cheng Zheng, Joann E MansonAbstract:BACKGROUND We recently presented associations between serum-based Biomarkers of carotenoid and tocopherol intake and chronic disease risk in a Women's Health Initiative (WHI) Measurement Precision subcohort (n = 5488). Questions remain as to whether self-reported dietary data can usefully augment such Biomarkers or can be calibrated using Biomarkers for reliable disease association estimation in larger WHI cohorts. OBJECTIVES The aims were to examine the potential of FFQ data to explain intake variation in a WHI Feeding Study and to compare association parameter estimates and their precision from studies based on Biomarker-calibrated FFQ intake in larger WHI cohorts, with those previously presented. METHODS Serum-based intake measures were augmented by using FFQ data in a WHI Feeding Study (n = 153). Corresponding calibration equations were generated, both in a companion Nutritional Biomarker Study (n = 436) and in the previously mentioned subcohort (n = 5488), by regressing these intake measures on dietary data and participant characteristics, for α- and β-carotene, lutein plus zeaxanthin, and α-tocopherol. The supplemental value of FFQ data was considered by examining the fraction of feeding study intake variation explained by these regression models. Calibrated intake and disease association analyses were evaluated by comparisons with previously reported subcohort results. RESULTS The inclusion of FFQ data led to some increases in feeding study intake variation explained (total R2 of ∼50%). Calibrated intake estimates explained 25-75% of serum-based intake variation, whether developed using either of the 2 cohort subsamples. Related disease associations for micronutrients were precisely estimated in larger WHI cohorts (n = 76,691) but were often closer to the null compared with previously reported associations. CONCLUSIONS FFQ data may usefully augment blood concentrations in estimating the intake of carotenoids and tocopherols. Calibrated intake estimates using FFQ, dietary supplement, and participant characteristics only may require further justification to ensure reliable estimation of related disease associations.
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Biomarkers of one carbon metabolism are associated with Biomarkers of inflammation in women
Journal of Nutrition, 2014Co-Authors: Clare Abbenhardt, Joshua W Miller, Xiaoling Song, Elissa C Brown, Ting Yuan David Cheng, Mark H Wener, Yingye Zheng, Adetunji T Toriola, Marian L NeuhouserAbstract:Folate-mediated one-carbon metabolism is essential for DNA synthesis, repair, and methylation. Perturbations in one-carbon metabolism have been implicated in increased risk of some cancers and may also affect inflammatory processes. We investigated these interrelated pathways to understand their relation. The objective was to explore associations between inflammation and Biomarkers of Nutritional status and one-carbon metabolism. In a cross-sectional study in 1976 women selected from the Women’s Health Initiative Observational Study, plasma vitamin B-6 [pyridoxal-5′-phosphate (PLP)], plasma vitamin B-12, plasma folate, and RBC folate were measured as Nutritional Biomarkers; serum C-reactive protein (CRP) and serum amyloid A (SAA) were measured as Biomarkers of inflammation; and homocysteine and cysteine were measured as integrated Biomarkers of one-carbon metabolism. Student’s t, chi-square, and Spearman rank correlations, along with multiple linear regressions, were used to explore relations between Biomarkers; additionally, we tested stratification by folic acid fortification period and multivitamin use. With the use of univariate analysis, plasma PLP was the only Nutritional Biomarker that was modestly significantly correlated with serum CRP and SAA (ρ = −0.22 and −0.12, respectively; P < 0.0001). Homocysteine (μmol/L) showed significant inverse correlations with all Nutritional Biomarkers (ranging from ρ = −0.30 to ρ = −0.46; all P < 0.0001). With the use of multiple linear regression, plasma PLP, RBC folate, homocysteine, and cysteine were identified as independent predictors of CRP; and PLP, vitamin B-12, RBC folate, and homocysteine were identified as predictors of SAA. When stratified by folic acid fortification period, nutrition-homocysteine correlations were generally weaker in the postfortification period, whereas associations between plasma PLP and serum CRP increased. Biomarkers of inflammation are associated with PLP, RBC folate, and homocysteine in women. The connection between the pathways needs to be further investigated and causality established. The trial is registered at clinicaltrials.gov as {"type":"clinical-trial","attrs":{"text":"NCT00000611","term_id":"NCT00000611"}}NCT00000611.
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use of recovery Biomarkers to calibrate nutrient consumption self reports in the women s health initiative
American Journal of Epidemiology, 2008Co-Authors: Marian L Neuhouser, Lesley F Tinker, Pamela A Shaw, Dale A Schoeller, Sheila Bingham, Linda Van Horn, Shirley A A Beresford, Bette J Caan, Cynthia A ThomsonAbstract:Underreporting of energy consumption by self-report is well-recognized, but previous studies using recovery Biomarkers have not been sufficiently large to establish whether participant characteristics predict misreporting. In 2004-2005, 544 participants in the Women's Health Initiative Dietary Modification Trial completed a doubly labeled water protocol (energy Biomarker), 24-hour urine collection (protein Biomarker), and self-reports of diet (assessed by food frequency questionnaire (FFQ)), exercise, and lifestyle habits; 111 women repeated all procedures after 6 months. Using linear regression, the authors estimated associations of participant characteristics with misreporting, defined as the extent to which the log ratio (self-reported FFQ/Nutritional Biomarker) was less than zero. Intervention women in the trial underreported energy intake by 32% (vs. 27% in the comparison arm) and protein intake by 15% (vs. 10%). Younger women had more underreporting of energy (p = 0.02) and protein (p = 0.001), while increasing body mass index predicted increased underreporting of energy and overreporting of percentage of energy derived from protein (p = 0.001 and p = 0.004, respectively). Blacks and Hispanics underreported more than did Caucasians. Correlations of initial measures with repeat measures (n = 111) were 0.72, 0.70, 0.46, and 0.64 for Biomarker energy, FFQ energy, Biomarker protein, and FFQ protein, respectively. Recovery Biomarker data were used in regression equations to calibrate self-reports; the potential application of these equations to disease risk modeling is presented. The authors confirm the existence of systematic bias in dietary self-reports and provide methods of correcting for measurement error.
Jones Kerry - One of the best experts on this subject based on the ideXlab platform.
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Erythrocyte transketolase activity coefficient (ETKAC) assay protocol for the assessment of thiamine (vitamin B1) status
'Organisation for Economic Co-Operation and Development (OECD)', 2020Co-Authors: Jones Kerry, Parkington Damon, Cox Lorna, Koulman AlbertAbstract:Vitamin B1 (thiamine) is an essential nutrient that acts as a cofactor for a number of metabolic processes, particularly in energy metabolism. Symptoms of classic thiamine deficiency are recognised as beriberi, although clinical symptoms are non-specific and recognition of sub-clinical deficiency is difficult. Therefore, reliable Biomarkers of thiamine status are required. Thiamine diphosphate (ThDP) is a cofactor for transketolase including erythrocyte transketolase (ETK).The ETK activity assay as an indirect, functional marker of thiamine status, has been used for over 50 years. The ETK activity assay provides a sensitive and specific Biomarker of thiamine status, however, there is a lack of consensus over the cut-offs for deficiency, partly due to a lack of assay harmonization. Here, we provide a step-by-step protocol for the measurement of ETK activity and calculation of the ETK activity coefficient (ETKAC), including detailed explanations of equipment and chemicals required and guidance for quality control procedures. Harmonization of protocol will provide the basis for the development of internationally recognized cut-offs for thiamine insufficiency. The establishment of quality control materials and a quality assurance scheme are recommended to provide reliability. This will ensure the ETK activity assay remains an important method for the assessment of thiamine status.KSJ, DAP and AK are supported by the National Institute for Health Research (NIHR) Cambridge Biomedical Research Centre (IS-BRC-1215- 20014). The NIHR Cambridge Biomedical Research Centre is a partnership between Cambridge University Hospitals NHS Foundation Trust and the University of Cambridge, funded by the NIHR. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care. LJC has an advisory role at the NIHR BRC Nutritional Biomarker Laboratory
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Erythrocyte transketolase activity coefficient (ETKAC) assay protocol for the assessment of thiamine status.
'Organisation for Economic Co-Operation and Development (OECD)', 2020Co-Authors: Jones Kerry, Parkington Damon, Cox, Lorna J, Koulman AlbertAbstract:Vitamin B1 (thiamine) is an essential nutrient that acts as a cofactor for a number of metabolic processes, particularly in energy metabolism. Symptoms of classic thiamine deficiency are recognised as beriberi, although clinical symptoms are non-specific and recognition of sub-clinical deficiency is difficult. Therefore, reliable Biomarkers of thiamine status are required. Thiamine diphosphate (ThDP) is a cofactor for transketolase including erythrocyte transketolase (ETK).The ETK activity assay as an indirect, functional marker of thiamine status, has been used for over 50 years. The ETK activity assay provides a sensitive and specific Biomarker of thiamine status, however, there is a lack of consensus over the cut-offs for deficiency, partly due to a lack of assay harmonization. Here, we provide a step-by-step protocol for the measurement of ETK activity and calculation of the ETK activity coefficient (ETKAC), including detailed explanations of equipment and chemicals required and guidance for quality control procedures. Harmonization of protocol will provide the basis for the development of internationally recognized cut-offs for thiamine insufficiency. The establishment of quality control materials and a quality assurance scheme are recommended to provide reliability. This will ensure the ETK activity assay remains an important method for the assessment of thiamine status.KSJ, DAP and AK are supported by the National Institute for Health Research (NIHR) Cambridge Biomedical Research Centre (IS-BRC-1215- 20014). The NIHR Cambridge Biomedical Research Centre is a partnership between Cambridge University Hospitals NHS Foundation Trust and the University of Cambridge, funded by the NIHR. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care. LJC has an advisory role at the NIHR BRC Nutritional Biomarker Laboratory
Maartje I Kester - One of the best experts on this subject based on the ideXlab platform.
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associations between nutrient intake and corresponding Nutritional Biomarker levels in blood in a memory clinic cohort the nudad project
Journal of the American Medical Directors Association, 2020Co-Authors: Francisca A De Leeuw, Philip Scheltens, Ellen G H M Van Den Heuvel, Ondine Van De Rest, Astrid S Doorduijn, Jay L P Fieldhouse, Marian A E De Van Der Schueren, Marjolein Visser, Charlotte E Teunissen, Maartje I KesterAbstract:Diet is a promising intervention target to prevent or slow Alzheimer's disease (AD). Early (predementia) stages of AD offer a unique opportunity for dietary interventions. Nutritional assessment methods to estimate nutrient intake have, however, not been validated in clinical populations. Hence, we assessed the association between nutrient intake assessed by food frequency questionnaire (FFQ) and nutrient status measured by Nutritional Biomarkers in blood in a clinical sample of controls, mild cognitive impairment (MCI), and patients with AD.
