A Metabolomics Approach to Profiling Chemicals of the Human Intestinal Tract
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A Metabolomics Approach to Profiling Chemicals of the Human Intestinal Tract


The use of mass spectrometry-based metabolomics analysis is a powerful technique to provide a comprehensive measurement of the chemical profile of biological samples. By observing the chemical composition of biological samples, we can better understand biological systems. All biological samples are chemically complex, but the human gastrointestinal tract is one of the most chemically complex matrices currently studied. This dissertation focuses on the approach, execution, and results of mass spectrometry-based metabolomics analysis of biological samples, with a focus on human gastrointestinal tract samples and approaches to better understand of the metabolome of the human gut. This research tests the hypothesis that the chemical profile of the human intestinal tract varies spatially, temporally and has high interindividual variation.Chapter one provides background information on mass spectrometry-based metabolomics methods. Experimental data are provided to emphasize important factors to consider when performing technically sound metabolomics analysis on different biological matrices. Bacteria, plant, blood, and stool experiments are reported with select publications included and methodological considerations for each sample type. Challenges in analysis presented by each matrix type are outlined and approaches to address these challenges are discussed with a focus on metabolite identification. Chapter two presents a metabolomics analysis of time-series human small intestinal samples. Samples were collected from the human jejunum over the course of one day and analyzed using four LC-MS/MS analytical platforms. A total of 828 metabolites were annotated within these samples and correlation-based clustering proved to be an efficient approach to connect metabolites with related biological function. This experiment reveals novel chemical and time-dynamic findings from within a human small intestine. Chapter three discusses data collected during targeted bile acid analyses. First bile acid analysis of blood and stool samples from a flaxseed dietary intervention study are reported, and then a study using a novel sampling method which allows samples to be retrieved from the small and large intestine of humans in vivo. Samples collected from the intestinal tract of 15 subjects reveal spatial variation and inter-individual variation in bile acid metabolism within the human gastrointestinal tract.

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