DRUM Collection: Nutrition & Food Science Theses and Dissertations

Methylseleninic Acid Sensitizes Notch 3-activated OVCA429 Ovarian Cancer Cells to Carboplatin

2013-02-07T04:12:47Z

Title: Methylseleninic Acid Sensitizes Notch 3-activated OVCA429 Ovarian Cancer Cells to Carboplatin Authors: Tzeng, Tiffany Jean Abstract: Ovarian cancer is the deadliest of gynecologic cancers and is usually diagnosed at advanced stage due to invalidated screening test. Although carboplatin has been used for treating ovarian cancer for years, high-grade serous ovarian cancer expressing a constitutively active form of the intracellular domain of Notch 3 develops resistance to this platinum-containing drug. Thus, finding a novel treatment or therapeutic targets are necessary. Here we test the hypothesis that the combinational treatment of methylseleninic acid (MSeA) and carboplatin, two chemicals displaying overlapping effect on DNA damage response, may target Notch 3 for improved efficacy on ovarian cancer treatment. The OVCA429/NICD3 cells expressing an activated form of Notch 3 were resistant to carboplatin, but co-treatment with MSeA synergistically sensitized the cell to an extent similar of that in OVCA429/pCEG control cells. The synergistic effect can be suppressed by the presence of a hydrogen peroxide scavenger N-acetyl cysteine (NAC) and kinase inhibitors of ATM and DNA-PKcs. In summary, MSeA and carboplatin synergistically sensitize OVCA429/NICD3 cells in a pathway involves oxidative stress, ATM and DNA-PKcs, suggesting a new strategy to improve the efficacy of carboplatin treatment for high-grade ovarian cancer.

The Role of Organic Matrices (dried turkey manure) in the Contamination and Survival of Salmonella spp. on Baby Spinach Leaves

2013-02-07T04:09:37Z

Title: The Role of Organic Matrices (dried turkey manure) in the Contamination and Survival of Salmonella spp. on Baby Spinach Leaves Authors: Oni, Ruth Adeola Abstract: Microbiological safety of fresh produce has attracted attention due to constant produce outbreaks. Manure contaminated with enteric pathogens has been identified as a major pre-harvest contamination source. This study investigated the survival of Salmonella in dust particles generated from dehydrated turkey manure, and how this could serve as an airborne contamination of leafy greens. Laboratory trials of the UV resistance of Salmonella in manure dust were also conducted to assess its protective effect; along with greenhouse studies to determine the survival of Salmonella in manure dust on spinach leaves. Results indicate survival times were inversely related to moisture content and particle size of manure dust. The presence of manure particles substantially enhanced the pathogen's survival under UV and reduced its inactivation on spinach leaves. This study presents data that could be used to assess the potential role of aerosolized manure as a pre-harvest risk factor for contamination of leafy greens.

Development of food polymer-based colloidal delivery systems for nutraceuticals

2013-02-07T04:11:45Z

Title: Development of food polymer-based colloidal delivery systems for nutraceuticals Authors: Luo, Yangchao Abstract: Colloidal delivery systems have drawn increasing attention in food science area. Biopolymers, i.e. proteins and polysaccharides originated from foods, with low toxicity, high biocompatibility and biodegradability, are the ideal biomaterials to develop delivery systems for nutraceuticals. The present work is dedicated to develop delivery systems for nutraceuticals, using food derived biopolymers, e.g. chitosan and zein. In the first part of this study, different core-shell structured nanoparticles were developed for encapsulating both hydrophilic and hydrophobic nutracetuicals. For chitosan nanoparticles with zein coating, the hydrophilic nutraceutical, selenite, was encapsulated and the physicochemical properties was improved after zein coating. Then, zein nanoparticles with chitosan (CS) or carboxymethyl chitosan (CMCS) coating were developed to encapsulate hydrophobic nutraceuticals, including vitamin E, vitamin D3, indole-3-carbinol and diindolylmethane. The fabrication parameters were systematically studied and the effects of encapsulation on stabilities of nutraceuticals were investigated under different conditions. Subsequently, a novel approach to prepare CMCS hydrogel beads was developed. CMCS, a water-soluble derivative of CS, was known as unable to form hydrogel beads by itself in aqueous solution due to chain rigidity and inefficient entanglement. In this part, the formation of CMCS hydrogel beads was studied in aqueous-alcohol binary solutions. Chemical crosslinking was required to maintain its integrity upon drying. Different drying methods (i.e. freeze and air drying) were also investigated to understand their effects on swelling and release profile in simulated gastrointestinal conditions. Some possible mechanisms were discussed. Lastly, cellular evaluation of zein nanoparticles stabilized by caseinate was carried out. The zein-caseinate nanoparticles had a good redispersibility after freeze-drying and were able to maintain original particle size in different cell culture medium and buffer at 37°C over time. The zein-caseinate nanoparticles had no cytotoxicity at concentrations up to 1 mg/ml over 3 days. Then, coumarin 6, a fluorescent marker, was encapsulated into zein-caseinate nanoparticles to investigate their cell uptake and epithelial transport. The cell uptake was clearly visualized by fluorescent microscopy and the uptake mechanisms were investigated. The epithelial transport was investigated on Caco-2 cell monolayers. The results suggested caseinate not only stabilized zein nanoparticles in different buffers, but also improved cell uptake and epithelial transport.

The Development of Food Polymer-Based Nanocomposites as Novel Antimicrobial Agents and Sustainable Packaging Materials

2013-02-07T03:53:23Z

Title: The Development of Food Polymer-Based Nanocomposites as Novel Antimicrobial Agents and Sustainable Packaging Materials Authors: Zhang, Boce Abstract: Nanocomposites developed from food polymers are an emerging technology, which has shown plenty of promising applications in worldwide food related markets. The dissertation first investigated how protein modification determined structural and functional properties of nanocomposites. The study then developed simple preparation methods for food polymer nanocomposites with two potential novel applications, including low toxic antimicrobial agent and high performance sustainable packaging material. First, the study investigated the effects of chemical modification on protein structures and properties. The glutamine rich protein, zein, was selected to study how deamidation via acid and base may affect structural, mechanical, and antioxidant properties of zein. High cysteine protein, alpha-lactalbumin (ALA), was then used to investigate how redox modification of cysteine groups may determine the functional property of ALA. The first potential application of food polymer nanocomposites is to lower the toxicity of silver-based antimicrobial agent. Although silver has renowned broad-spectrum antimicrobial activities, the use was still restricted by its toxicity from low biocompatibility and argyria (skin discoloration). In this study, silver-zein and silver-ALA nanocomposite showed promising capability to substantially reduce the toxicity of silver. The silver/protein nanocomposites may find a solution for the current challenge of silver-based antiseptics. Another potential application of food polymer nanocomposites is to modify sustainable film made of food polymers to develop biodegradable plastic materials with improved mechanical and barrier properties. Theoretical studies have proven that a well-ordered nanocomposite structure could provide maximum functionality improvement, but such structure was largely unachieved. A simple and cost effective method was developed in this study using ferromagnetic nanoplatelet as nanofiller materials to achieve highly-arranged structure. Thus prepared zein/Fe3O4 nanocomposite had improved mechanical and gas barrier properties.