Quantitation of Tocopherol Metabolism in Humans

人类生育酚代谢的定量

基本信息

批准号：
7637872
负责人：
ANDREW JOSEPH CLIFFORD
金额：
$ 20.93万
依托单位：
UNIVERSITY OF CALIFORNIA AT DAVIS
依托单位国家：
美国
项目类别：
财政年份：
2008
资助国家：
美国
起止时间：
2008-07-01 至 2011-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7637872
关键词：
Adult Affect Antioxidants Apolipoproteins B Atherosclerosis Attention Behavior Bile fluid Biological Biological Availability Biological Process Blood Blood Platelets Cardiovascular Diseases Catabolism Chemicals Child Cholesterol Chronic Disease Data Data Set Dose Ensure Enzymes Equilibrium Erythrocytes Extrahepatic Feasibility Studies Feces Flying body movement Folate Food Generic Drugs Goals Hepatocyte High Pressure Liquid Chromatography Human Human body Hypertension Intake Isotopes Kidney Kinetics Label Laboratories Learning Life Link Lipids Lipoproteins Liver Location Lymphocyte Malignant Neoplasms Measures Metabolic Metabolism Methods Milk Modeling Names Olive oil preparation Oral Administration Phase Physiological Plasma Play Pregnant Women Process Protocols documentation Radiation Radioactive Recommendation Recruitment Activity Reporting Research Risk Role Sampling Scientist Single Nucleotide Polymorphism Solid Stable Isotope Labeling Stereoisomer Study Subject Testing Time Tissues Tocopherols Tracer Urine Vitamin E Vitamins Woman absorption accelerator mass spectrometry atherogenesis base density design experience extracellular healthy volunteer human tissue improved in vivo men nutrition oxidation prevent public health relevance residence stable isotope vitamin metabolism volunteer

项目摘要

DESCRIPTION (provided by applicant): There is growing evidence that a-tocopherol, the active form of vitamin E, may help minimize the risk of certain chronic diseases such as cardiovascular disease, hypertension and cancer. Still, more research on vitamin E is needed to fully understand its metabolism and function(s). The IOM/NAS has listed key research recommendations for vitamin E. The list included quantifying vitamin E metabolism; determining whether mass balance is feasible and vitamin E requirements can be estimated using stable isotope-labeled vitamin E; determining whether vitamin E metabolism as it occurs in vivo in humans can be quantified; determining how, where, and how fast vitamin E is degraded; identifying the metabolic intermediates during metabolism; and determining whether they have biological function. The long term goal of this application is to quantify the dynamic and kinetic behavior of vitamin E metabolism as it might occur in vivo in humans using kinetic modeling of the fate of true tracer doses of 14C-vitamin E that ensure steady state conditions of vitamin E metabolism that are relevant and useful to nutrition, and where our study subjects are not asked to accept risks significantly greater than those experienced in everyday life; i.e., radiation exposures < those obtained in flying for 1-4 h, a common radiation exposure, even for young children and pregnant women. The following specific aims will achieve our long term goal. Specific aim # 1: Determine the absorption, accretion, distribution, and elimination of RRR-a-TOC in humans. To accommodate this, we will quantify the transfer of 14C-RRR-a-TOC among various lipoprotein classes and its metabolites by time since dose. Specific aim # 2: Construct a dynamic and kinetic model of 14C-RRR-a-TOC metabolism as it might occur in vivo in humans to test the hypothesis whether EHT-a-TOC is eliminated by a "reverse a-TOC transfer" process. The null hypothesis is that EHT-a-TOC eliminated through "reverse cholesterol transfer." Plasma lipoproteins play key roles in delivering RRR-a-TOC to and from EHT. For this purpose 12 volunteers, 6 women and 6 men, will be recruited and administered a single dose of 14C-RRR-a-tocopherol (100 nCi) that will be added to a cup containing a whipped mix of 10.5 g olive oil and 30 g skim milk. We will follow the 14C tracer over a 60-day period. The long term goal of this project is to quantify the dynamic/ kinetic behavior of vitamin E metabolism in vivo in humans of the RRR-a-TOC and of its 2R stereoisomer forms using a test re-test design. In addition, using a mechanistic model of tocopherol metabolism we can determine whether or not single nucleotide polymorphisms (SNPs) in tocopherol-relevant enzymes affects the kinetic behavior of human tocopherol metabolism as we recently show for folate Clifford et al. 2006. Baseline blood (10 mL) will be taken just before dosing and at various intervals until 60 days post dose to ensure that the 14C labeled a-tocopherol is fully equilibrated into the slowest turning over a-tocopherol pool that can affect the plasma kinetics late in a study. The lipoprotein classes will be separated using a new protocol. Erythrocytes, lymphocytes, and platelets will also be separated. Urine and feces will be collected until 30 days post dose. The 14C content of each biological sample will be measured at the Center for the Accelerator Mass Spectrometry at Lawrence Livermore National Laboratory (Livermore, CA). Chemical identity of the 14C in plasma and plasma lipoprotein samples will also be determined, 14C-RRR-a-tocopherol, a-CEHC, a-CPHC plus 4 more unknowns by using non-radioactive standards in an HPLC. We will construct a dynamic/kinetic model of a-tocopherol metabolism, we have already demonstrated the feasibility of our approach. We will use a high sampling density of plasma over a relatively long time since dosing to acquire a much more detailed/complete dataset than any already existing dataset. Then if specific metabolic functions for a-tocopherol can be stipulated, it will be possible to determine a minimum intake of a-tocopherol to sustain these critical functions, such as, preventing oxidation of lipoproteins, which has been linked to atherogenesis, and therefore minimizing the risk of atherosclerosis. PUBLIC HEALTH RELEVANCE: Vitamin E is a generic name for a group of lipid-soluble compounds known as tocopherols that have different formulas. These Vitamin E formulas occur naturally in many foods and act as biological antioxidants. Previous studies have shown differences in the way humans metabolize vitamin E. Since metabolism of the vitamin is poorly understood especially at normal physiological levels, in vivo studies under physiological conditions are needed in humans to understand it. Therefore, UC Davis Scientists are conducting a study with approximately 12 healthy volunteers to evaluate the metabolism of a single oral administration of tracer amounts of the RRR- (natural form) of vitamin E to learn more about how the human body utilizes this vitamin. Particular attention will be directed to the absorption phase. The results are expected to provide information about vitamin E biopotency and eventually improved Dietary Recommendations.

描述（由申请人提供）：越来越多的证据表明，α-生育酚（维生素 E 的活性形式）可能有助于降低某些慢性疾病的风险，例如心血管疾病、高血压和癌症。尽管如此，仍需要对维生素 E 进行更多研究，以充分了解其代谢和功能。 IOM/NAS 列出了维生素 E 的关键研究建议。该列表包括量化维生素 E 代谢；确定质量平衡是否可行，并且可以使用稳定同位素标记的维生素 E 来估计维生素 E 需求；确定是否可以量化人体体内发生的维生素 E 代谢；确定维生素 E 降解的方式、地点和速度；识别代谢过程中的代谢中间体；并确定它们是否具有生物学功能。该应用的长期目标是量化维生素 E 代谢的动态和动力学行为，因为它可能在人体体内发生，使用 14C-维生素 E 的真实示踪剂量的命运的动力学模型，确保维生素 E 的稳态条件与营养相关且有用的新陈代谢，并且我们的研究对象不被要求接受比日常生活中经历的风险大得多的风险；即，辐射暴露 < 飞行 1-4 小时所获得的辐射暴露，这是一种常见的辐射暴露，即使对于幼儿和孕妇也是如此。以下具体目标将实现我们的长期目标。具体目标#1：确定 RRR-a-TOC 在人体中的吸收、积累、分布和消除。为了适应这一点，我们将按给药后的时间量化 14C-RRR-a-TOC 在各种脂蛋白类别及其代谢物之间的转移。具体目标#2：构建 14C-RRR-a-TOC 代谢的动态和动力学模型，因为它可能发生在人体体内，以测试 EHT-a-TOC 是否通过“反向 a-TOC 转移”过程消除的假设。零假设是 EHT-a-TOC 通过“反向胆固醇转移”消除。血浆脂蛋白在将 RRR-a-TOC 往返于 EHT 的过程中发挥着关键作用。为此，将招募 12 名志愿者，其中 6 名女性和 6 名男性，并给予单剂 14C-RRR-a-生育酚 (100 nCi)，将其添加到含有 10.5 克橄榄油和 30 克橄榄油的搅打混合物的杯子中。克脱脂牛奶。我们将在 60 天内跟踪 14C 示踪剂。该项目的长期目标是使用测试再测试设计来量化 RRR-a-TOC 及其 2R 立体异构体形式在人体体内维生素 E 代谢的动态/动力学行为。此外，利用生育酚代谢的机制模型，我们可以确定生育酚相关酶中的单核苷酸多态性 (SNP) 是否影响人类生育酚代谢的动力学行为，正如我们最近在叶酸 Clifford 等人中所展示的那样。 2006. 将在给药前和给药后 60 天之前以不同的时间间隔采集基线血液 (10 mL)，以确保 14C 标记的 α-生育酚完全平衡到可影响血浆动力学的最慢周转 α-生育酚池中学习迟到了。将使用新方案分离脂蛋白类别。红细胞、淋巴细胞和血小板也将被分离。将收集尿液和粪便直至给药后 30 天。每个生物样品的 14C 含量将在劳伦斯利弗莫尔国家实验室（加利福尼亚州利弗莫尔）的加速器质谱中心进行测量。血浆和血浆脂蛋白样品中 14C 的化学特性也将通过在 HPLC 中使用非放射性标准品来确定，14C-RRR-a-生育酚、a-CEHC、a-CPHC 以及另外 4 个未知物。我们将构建α-生育酚代谢的动态/动力学模型，我们已经证明了我们方法的可行性。我们将在给药后相对较长的时间内使用血浆的高采样密度，以获得比任何现有数据集更详细/完整的数据集。然后，如果可以规定α-生育酚的特定代谢功能，则可以确定维持这些关键功能的α-生育酚的最低摄入量，例如防止与动脉粥样硬化有关的脂蛋白氧化，从而最大限度地减少动脉粥样硬化的发生。动脉粥样硬化的风险。公共健康相关性：维生素 E 是一组称为生育酚的脂溶性化合物的总称，它们具有不同的化学式。这些维生素 E 配方天然存在于许多食物中，可作为生物抗氧化剂。先前的研究表明，人类代谢维生素E的方式存在差异。由于人们对维生素E的代谢知之甚少，尤其是在正常生理水平下，因此需要在人体生理条件下进行体内研究来了解它。因此，加州大学戴维斯分校的科学家们正在对大约 12 名健康志愿者进行一项研究，以评估单次口服示踪量维生素 E RRR（天然形式）的代谢情况，以更多地了解人体如何利用这种维生素。将特别关注吸收阶段。预计结果将提供有关维生素 E 生物效力的信息并最终改进膳食建议。