Thesis (M.S.)--University of Alabama at Birmingham, 2010. / Title from PDF title page (viewed Jan. 21, 2010). Includes bibliographical references (p. 32-40) .

Thesis (Ph. D.)--Florida State University, 2004. / Advisor: Dr. John G. Dorsey, Florida State University, College of Arts and Sciences, Dept. of Chemistry and Biochemistry. Title and description from dissertation home page (viewed June 16, 2004). Includes bibliographical references.

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references (leaves 148-155). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references (leaves 101-107). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references (leaves 114-126). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references (leaves 148-155). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references (leaves 101-107). Also available on the Internet.

Parenteral nutrition (PN) is a method of feeding those incapable of absorbing nutrients from the gastrointestinal tract. All required nutrients are combined in one "big bag". Consequently, many chemical interactions are possible between components. Ascorbic acid (AA) is ubiquitous to both animal and plant kingdoms. Although its biochemistry is not fully understood, dietary deficiency is detrimental to well being, with the most extreme condition being scurvy. AA is water-soluble and frequent intake is therefore required to maintain nutritional status. AA is possibly the most reactive additive in PN mixtures, readily reacting with dissolved oxygen, initially producing dehydroascorbic acid (OHAA). OHAA retains the biological activity of AA. It was the purpose of this study to further knowledge regarding stability of AA and OHAA in PN mixtures, informing pharmaceutical practice to improve safety and efficacy of PN. A stability-indicating HPLC method was optimised for the study of AA and OHAA in PN mixtures. A study of the kinetics of OHAA degradation was undertaken to provide data that could be used to predict OHAA stability. Results obtained indicated a first order reaction. In direct contrast to AA degradation, trace elements did not catalyse OHAA degradation. A further product of AA degradation is oxalic acid (OA) which is potentially toxic. A HPLC method for the determination of OA in PN mixtures was developed and validated, although minimum quantification limits were relatively high (~10J.Lg/ml).The method was used to assess OA appearance in stored PN mixtures, with results indicating that concentrations remained below 10J.Lg/ml even after 35 days storage. The final aspect of this research was to investigate the most likely components of a PN mixture which may "protect" AA from oxidation. a-tocopherol photo-oxidises and therefore may compete with AA for oxygen. As light catalyses the reaction it is possible oxygen reacts more rapidly with a-tocopherol compared with AA. Results indicated 0.- Tocopherol did not oxidise in preference to AA and therefore offered no "protection". Cysteine is a reducing agent included in some amino acid preparations. The average dissolved oxygen content of standard adult PN mixtures was determined, from which the amount of cysteine required to react with dissolved oxygen was calculated. AA instability in PN mixtures was compared with and without cysteine. Results indicated that adding cysteine to PN mixtures 24 hours before addition of AA, resulted in retention of >95% AA. Results obtained from this study have furthered knowledge of the AA degradation profile, its kinetics and the potential influence of other components in PN mixtures. In particular potential strategies for minimising AA degradation are identified therefore ensuring patients receive quantities approaching those prescribed.

Along with genes and proteins, metabolites play important roles in sustaining life. There remains much to be learned about the in vivo roles of metabolites. Metabolomics is a comparative tool to study global metabolite levels in samples under various conditions. This dissertation describes the development and application of metabolomics strategies for discovery of biologically active or novel metabolites with priori knowledge about genes, proteins, or phenotypes. The power of metabolomics for discovery of novel metabolites from genes is demonstrated through the work with the pyochelin (pch) gene cluster. Comparison of the extracellular metabolomes of pch gene cluster mutants to the wild-type Pseudomonas aeruginosa (strain PA14) identified 198 ions regulated by the pch genes. In addition to known metabolites, a pair of novel metabolites were characterized as 2-alkyl-4,5-dihydrothiazole-4-carboxylates (ATCs). Subsequent assays revealed that ATCs bind iron and that their production is regulated by iron levels and dependent on pchE gene in the pch gene cluster. Metabolomics can also facilitate discovery of active metabolites from proteins, as shown in the work with orphan nuclear receptor Nur77. We applied a metabolomics platform for detected protein-metabolite interactions to identify lipids that bind to Nur77. Using this approach, we discovered that the Nur77 ligand-binding domain (Nur77LBD) enriched unsaturated fatty acids (UFAs) in tissue lipid mixtures. Subsequent biophysical and biochemical assays indicate that UFAs bind to Nur77LBD to cause changes in the conformation and oligomerization of the receptor. Last, analogous to classic fractionation experiments, metabolomics can also be applied to discover active metabolites from phenotypes. Using combination of genetics, biochemistry, and metabolomics, we identified three phenazine compounds produced by Pseudomonas aeruginosa that are toxic to the nematode Caenorhabditis elegans. 1-hydroxyphenazine, phenazine-1-carboxylic acid (PCA), and pyocyanin are capable of killing nematodes in a matter of hours. 1-hydroxyphenazine is toxic over a wide pH range, whereas the toxicities of PCA and pyocyanin are strictly pH-dependent at non-overlapping pH ranges. The diversity within a class of metabolites can be used to modulate bacterial toxicity in different environmental niches. / Chemistry and Chemical Biology

(Uncorrected OCR) Abstract Porphobilinogen (PBG) synthase condenses two molecules of aminolaevulinic acid (ALA) to form PBG in heme biosynthesis. The enzyme activity is sensitive to inhibition by heavy metals such as lead. It can act as a biological indicator of chronic lead POis~r\g to identify the risk group, especially in children, so that early treatment can be given to prevent possible permanent damages. A reversed-phase ion-pair HPLC analytical method for the assay of the PBG synthase activity based on detection of PBG production has been validated. A Hypersil CN column (150 x 4.6 mm; 5 urn) was employed together with a mixture of acetonitrile-40 mM phosphate buffer at pH 2.4 with 5 mM 1-heptanesulphonic acid (8:92, v/v). UV detection was performed at 240 nm. PBG was eluted as a spectrally pure peak resolved from its impurities in the methanol-inhibited enzyme reaction. The method was sensitive with a limit of quantitation of 2 ~M. The within-run and between-run precisions were 8.2% and 13.8% respectively. The recovery was 93.4 �7.1% (n=6). The preliminary reference range of the PBG synthase activities in the local pediatric population were from 21.5 to 26.3 ~mol/L RBC/min. Bland and Altman statistical analysis showed that the HPLC assay and the colorimetric assay could not be used interchangeably. The HPLC assay was an alternative way to assess the PBG synthase activities in the human erythrocyte samples. IV / abstract / toc / Medical Sciences / Master / Master of Medical Sciences