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Title: | Multisegment Injection-Nonaqueous Capillary Electrophoresis-Mass Spectrometry Based Metabolomics for Rapid Analysis of Fatty Acids for Dietary and Cardiometabolic Risk Assessment |
Authors: | Azab, Sandi |
Advisor: | Britz-McKibbin, Philip |
Department: | Chemistry and Chemical Biology |
Publication Date: | 2020 |
Abstract: | Biomarkers play a key role in human health for early disease screening for public health, improved diagnosis of human diseases, and monitoring of treatment responses on an individual level. However, there is urgent need for high throughput technologies to accelerate biomarker discovery based on comprehensive analyses of metabolites and lipids in complex human biofluids. This thesis contributes to new advances in metabolomics research and biomarker discovery in three major areas. In specific, this thesis describes (1) the development and validation of a multiplexed separation platform based on multisegment injection-nonaqueous capillary electrophoresis-mass spectrometry (MSI-NACE-MS) for the rapid and accurate determination of fatty acids and synthetic environmental lipids in blood specimens, (2) the application of this technique in support of nutritional epidemiology for objective assessment of dietary fat intake in women that can be correlated with self-reported food frequency questionnaires, and (3) the discovery of a panel of serum biomarkers for differentiation of peripheral artery disease (PAD) in older persons at high risk for limb amputation and death. Chapter I provides an introduction in biomarkers and metabolomics, including an overview of the data workflow when performing comprehensive metabolite profiling with emphasis on methods applicable to comprehensive fatty acid analysis. Chapter II introduces a novel assay based on MSI-NACE-MS for high throughput analyses of nonesterified or total hydrolyzed fatty acids in serum/plasma extracts following a rigorous method optimization and an inter-method comparison to conventional gas chromatography (GC) to demonstrate good mutual agreement. MSI-NACE-MS enables multiplexed analyses of seven samples within a single run with stringent quality control, robust inter-batch correction, and accurate electromigration modeling for lipid identification without pre-column chemical derivatization and complicated sample workup procedures. Chapter III further expands concentration sensitivity when using MSI-NACE-MS/MS for rapid biomonitoring of low nanomolar levels of perfluoroalkyl substance (PFAS) exposures as they are a class of ubiquitous environmental pollutants with endocrine-disruption functions. Perfluorooctanoic acid and perfluorooctanesulfonic acid were quantified in a subset of serum extracts from pregnant women before and after 2009 with lower exposures measured in accordance with enforced PFAS regulation. Chapter IV demonstrates the clinical utility of circulating NEFA for accurate nutritional assessment of fat intake in women. MSI-NACE-MS was applied in observational and intervention studies to demonstrate that polyunsaturated omega-3 and saturated odd-chain NEFAs serve as promising dietary biomarkers to monitor intake of oily fish/fish oil supplement and full-fat dairy intake, respectively. Chapter V describes an untargeted characterization of the serum metabolome of nondiabetic PAD patients for differentiation of chronic limb-threatening ischemia from intermittent claudication as compared to the ankle brachial index. A panel of serum metabolites, including several amino acids and fatty acids were identified as promising clinical biomarkers for early diagnosis and/or prognostication of PAD that also provides insights into its underlying pathophysiology. Lastly, Chapter VI provides an overview of the major contributions derived from this thesis, as well as a perspective on future research initiatives. |
URI: | http://hdl.handle.net/11375/25872 |
Appears in Collections: | Open Access Dissertations and Theses |
Files in This Item:
File | Description | Size | Format | |
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Azab_Sandi_M_2020August_PhD.pdf | 11.08 MB | Adobe PDF | View/Open |
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