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 Washington, 2001. / Vita. Includes bibliographical references (leaves 87-123).

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.

The cost of pretreatment process for saccharification from biomass and the cost of dilute ethanol purification are significant components of the overall cost for fuel grade ethanol production through fermentation or other biological routes. This work focuses on developing optimal designs of dilute ethanol purification process and the new acid hydrolysis technology for the production of fermentable sugars from biomass where the overarching goal is to reduce the cost of ethanol production from biomass. In this thesis, the ethanol separation process with the reverse osmosis membrane pretreatment is developed to reduce separation cost and energy consumption especially when the feed is dilute. In addition, the new solid phase reactive separation system for biomass saccharification via acid hydrolysis is proposed. This new process is applied for both dilute and concentrated acid hydrolysis where the goal is to increase sugar yield and to reduce byproduct formation. The reaction kinetics of the concentrated acid hydrolysis is investigated through batch experiment. All of these use optimization approaches for seeking the best process designs and for parameter estimations.

Retail stores are an environment with a rich diversity of toxic chemicals typically found in consumer products. Among these chemicals, semi-volatile organic compounds (SVOCs) are an important class with great health concerns. Phthalates and polybrominated diphenyl ethers (PBDEs) are high production volume SVOC chemicals pervasively used in plastics and other consumer products. Exposure to them may cause serious adverse health effects, including endocrine disruption. They, however, have not been widely studied in retail environments. In this study, indoor air samples were collected from 15 retail stores in Austin, TX and University Park, PA. Some of these stores were revisited on different temperate seasons to account for weather variability. Indoor concentrations of the most ubiquitous pollutants were correlated with several building characteristics, including retailer type, temperature, and building use characteristics. Collected data shows a wider variety of phthalates and PBDEs, as well as higher indoor airborne concentrations for large department stores as compared to grocery stores, which typically have fewer sources in comparison. / text

The corneal wound healing response involves the activation of keratocytes to proliferate from a quiescent phenotype. The mitogens that cause the initial transformation of the quiescent keratocytes to the active phenotype have not been identified. Even though serum is commonly used to replicate this in vitro, the cornea is avascular and therefore likely not exposed to serum. In the first part of this dissertation, a DMEM/F12 extract of corneal stromas was made and shown to stimulate keratocyte proliferation in both a dose-dependent and cell-density dependent manner. This extract contains mitogens that differ from the mitogens present in serum based on their effect on keratocytes and their biochemical characteristics. Culture in extract replicates in vitro the changes observed during the activation of keratocytes in the wound-healing phase.The corneal stroma contains an extensive extracellular matrix that consists primarily of collagens and proteolgycans. This matrix is maintained and secreted by the keratocytes, cells with unique characteristics lost during the activation observed at wound healing. The second part of this dissertation aims to develop a defined culture medium that maintains the keratocyte phenotype during proliferation. Keratocytes were cultured in serum-free medium and the effect of the growth factors on the markers for the keratocyte phenotype determined. Only insulin was shown to stimulate cell proliferation in a consistent manner, while maintaining commonly accepted keratocyte markers. When this defined culture medium was supplemented with ascorbic acid to study collagen synthesis, a marked increase in both collagen synthesis and keratan sulfate proteoglycan accumulation was measured. This newly developed culture medium, containing insulin and ascorbate, allows for cell growth, maintains the keratocyte markers, and could be used to study the native, non-activated keratocyte phenotype in culture.This dissertation shows that the culture media described herein replicate in vitro all the phenotypes observed during the corneal wound healing response in vivo. These culture media, in turn, could be used to obtain more knowledge about the different keratocyte phenotypes, and how they could be manipulated in culture. (329 words)

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