UMD Theses and Dissertations

Permanent URI for this collectionhttp://hdl.handle.net/1903/3

New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.

More information is available at Theses and Dissertations at University of Maryland Libraries.

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    Absorption and metabolism of 3-MCPD 1-monopalmitate in rats
    (2017) Gao, Boyan; Yu, Liangli (Lucy); Food Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Fatty acid esters of 3-monochloropropane 1,2-diol (3-MCPD esters) are a group of potential chemical toxicants. Their toxic effects primarily include nephrotoxicity and hepatotoxicity. To understand the toxic mechanisms of 3-MCPD esters, one of the key points is to advance the understanding of their metabolic mechanisms in vivo. This dissertation investigated 1) the absorption and kinetics of 3-MCPD 1-monopalmitate in rats, 2) the possible metabolites of 3- MCPD 1-monopalmitate after oral administration to rats, and 3) the possible metabolic pathways of 3-MCPD 1-monopalmitate in vivo. The greatest concentration of 3-MCPD 1-monopalmitate in the plasma was 873.72 ng/mL (Cmax) at about 1.67 hours (Tmax) after oral administration. The concentration of 3-MCPD 1-monopalmitate reduced to half after 3.42 hours (t1/2). No 3-MCPD 1-monopalmitate could be detected after 4 hours, which was its mean resident time (MRT). The area under curve (AUC) for 3-MCPD 1-monopalmitate in rat plasma was 1676.15 h.ng/mL, which represented the maximum amount of 3-MCPD 1-monopalmitate absorbed into plasma under the testing conditions. Beside, 39 possible metabolites were tentatively identified in the liver, kidney, testis, brain, plasma and urine samples at 6, 12, 24 and 48 hours after oral administration of 3-MCPD 1-monopalmitate to rats. In addition, five major metabolic pathways of 3-MCPD esters were derivate to evaluate their metabolic conditions in vivo. These results can greatly enhance the understanding about the absorption, distribution and metabolism conditions of 3-MCPD esters in vivo, and promote further research about the biological actions of 3-MCPD esters.
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    Associations between Urinary Phthalates and Metabolic Syndrome in NHANES 2005-2010
    (2015) Haque, Mefruz Salwa; Dallal, Cher M; Epidemiology and Biostatistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Phthalates, commonly used to make plastics more durable, are a group of endocrine disrupting chemicals (EDC), with potential for adverse metabolic consequences. Associations between exposure to 13 phthalate metabolites and the prevalence of metabolic syndrome (MetS) were examined among 5,409 U.S adults ≥ 18 years of age, who participated in the National Health and Nutrition Examination Survey from 2005-2010. MetS was assessed using clinical and questionnaire data. Odds Ratio (OR) and 95% Confidence Intervals (CI) adjusting for age, creatinine and key confounders, were estimated with multivariable logistic regression. Positive associations were observed between individual phthalate metabolites and MetS: (MCOP OR=1.31, 95% CI=1.40, 1.64, p-trend<.01; MCPP OR=1.39, 95% CI=1.09, 1.77, p-trend=0.01). In gender stratified analyses, findings with MCOPP and MCPP were restricted to women only. Phthalate metabolites may increase the prevalence of MetS; however, further studies are needed to better understand the role of EDCs in the development of MetS.
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    Chronic Ingestion of (3R,3'R,6'R)-Lutein and (3R,3'R)-Zeaxanthin in Female Rhesus Macaque Primates
    (2006-05-08) London, Edra; Khachik, Frederick; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Age-related macular degeneration (AMD) is the leading cause of blindness in developed countries in individuals over the age of 65. High intake of the dietary carotenoids lutein (L) and zeaxanthin (Z) is believed to reduce the risk of AMD. This study investigated the effects of long-term supplementation of primates with high doses of L or Z, and their 1:1 combination, and whether high supplemental doses cause ocular toxicity. Eighteen female rhesus macaques were divided into 4 groups: control (n=3), L-treated (n=5, 9.34 mg/kg L and 0.66 mg/kg Z), Z-treated (n=5, 10 mg/kg Z), and L/Z-treated (n=5, L and Z each at 0.5 mg/kg). At 6 month intervals beginning at baseline, plasma samples were analyzed by HPLC for L, Z, and their metabolites. Carotenoid analysis of tissues, ocular examinations, and toxicity assays were performed. High-dose supplementation of primates with L or Z significantly increased plasma, and ocular and other tissue concentrations of these carotenoids and their metabolites in most cases. Supplementation with a 1:1 dose of L and Z increased plasma concentrations of these carotenoids after 6 months, but baseline and month 12 levels in plasma and ocular tissues were not significantly different. Supplementation of primates with L or Z at high doses does not cause ocular or kidney toxicity.