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Articles 1 - 16 of 16
Full-Text Articles in Life Sciences
The Catalytic Urease Subunit Urec Is Critical For Bifidobacterium Longum Urea Utilization, Yang Lyu
The Catalytic Urease Subunit Urec Is Critical For Bifidobacterium Longum Urea Utilization, Yang Lyu
Doctoral Dissertations
In the first study, we investigated the utilization of a human milk nitrogen source, urea, by Bifidobacterium. Urea accounts for ~15% in human milk, which is an abundant non-protein nitrogen (NPN). Some bifidobacteria are found to harbor urease gene clusters that potentially enable their hydrolysis of the human milk urea. However, the underlying mechanisms are still unclear. To incisively link the urease gene cluster with bifidobacterial urea utilization, chemical mutagenesis (i.e. ethyl methanesulfonate) was performed on the urease-positive Bifidobacterium longum subsp. suis UMA399. Mutants were selected on differential media and genetic lesions were identified using whole genome sequencing. …
Cytochrome P450 Monooxygenase-Mediated Lipid Metabolism In Obesity And Colon Tumorigenesis, Weicang Wang
Cytochrome P450 Monooxygenase-Mediated Lipid Metabolism In Obesity And Colon Tumorigenesis, Weicang Wang
Doctoral Dissertations
Colon cancer is a major public health issue: it is expected to have 140,250 new cases and 50,630 deaths during 2018, making colon cancer the third most common type of cancer and the second leading cause of cancer death in the United States. Obesity is associated with enhanced colonic inflammation, which is a major risk factor of colorectal cancer. Currently, more than 35% of adults and nearly 17% of children are obese. Considering the obesity and colon cancer epidemic in the United States, there is an urgent need to identify novel therapeutic targets for obesity and colon cancer. Here, using …
Silver Mirror Substrate And Rolling Method For Improved Surface-Enhanced Raman Spesctroscopic Analysis In Food, Yanqi Qu
Doctoral Dissertations
Surface-enhanced Raman spectroscopy, short for SERS, is an emerging technology with great potential in food analysis due to rapid detection, high sensitivity, portable instrumentation, and simple sample preparation. However, it is always a bottleneck to obtain reproducible SERS measurements in real analytical cases due to the complicity of food systems and inhomogeneous aggregation of colloidal nanoparticles. To improve its performance for practical applications in food analysis, efforts have been made in improving the reproducibility, enhancing the selectivity and reducing the matrix interference to the analyte. Herein, a self-assembly silver nanoparticles mirror substrate was fabricated to improve the and the quantitative …
Effects Of Ivermectin And Perfluorobutanesulfonic Acid (Pfbs) On Lipid Metabolism, Weipeng Qi
Effects Of Ivermectin And Perfluorobutanesulfonic Acid (Pfbs) On Lipid Metabolism, Weipeng Qi
Doctoral Dissertations
Accumulating evidence has shown a link between environmental contaminants and altered lipid metabolism. There is currently, however, limited knowledge regarding the causal molecular mechanisms. Therefore, we investigated the molecular mechanisms of two environmental contaminants, ivermectin and perfluorobutanesulfonic acid (PFBS), on lipid metabolism in adipocytes and hepatocytes using cell culture models. We first studied the effects of ivermectin, an anti-parasitic agent, on the adipogenesis of 3T3-L1 preadipocytes. Our current results suggest that ivermectin inhibits adipogenesis in 3T3-L1 preadipocytes and the expression of adipogenic genes where these effects were found to be partially via PPARγ-dependent, but not FXR-dependent, pathway. Additionally, ivermectin also …
Dietary Oligosaccharides Are Differentially Metabolized By Commensal Microbiota Within In Vitro Model Systems, Ezgi Özcan
Doctoral Dissertations
Our diet contains indigestible carbohydrates that are available for microbial metabolism within the gastrointestinal tract. These carbohydrate sources are oligosaccharides found in plants and human milk. Oligosaccharide utilization phenotypes are often consistent with the ecological niche that microbes occupy (e.g. adult gut, infant gut, plants). This study represents an in-depth metabolic analysis for utilization of human milk oligosaccharides (HMOs) including lacto-N-tetraose (LNT) and lacto-N-neotetraose (LNnT), and cranberry oligosaccharides (i.e. xyloglucans) within in vitro modeled systems. These model systems include microplate systems for pure cultures as well as an adapted bioreactor system to mimic microbial interactions within the gut. Infant-colonizing Bifidobacterium …
Surface-Enhanced Raman Spectroscopic Imaging Of Bacteria Within Fresh Produce In Situ, Michael Hickey
Surface-Enhanced Raman Spectroscopic Imaging Of Bacteria Within Fresh Produce In Situ, Michael Hickey
Doctoral Dissertations
The growth curves for E. coli O157:H7 (#043888) are reported. We make the case that the onset of stationary growth is the optimal point at which a bacteria culture is considered suitable for quantitative Raman analyses. The optimal conditions for 3-mercaptophenylboronic acid coating of bacteria cells is also reported. Fundamental drawbacks of the status-quo approach have been elucidated and overcome, based on measurable improvements to the experimental methodology. This approach is shown to be suitable for the evaluation of bacterial rinse-washing efficacy by means of Raman light-scattering. The data were compared to label-free applications and the measurable differences between each …
Application Of Flow Cytometry As Novel Technology In Studying Lipid Oxidation In Oil-In-Water Emulsions, Peilong Li
Application Of Flow Cytometry As Novel Technology In Studying Lipid Oxidation In Oil-In-Water Emulsions, Peilong Li
Masters Theses
The body of literature on the impact of emulsion particle size on oxidation rates is unclear. This could be because emulsions are typically polydisperse and the oxidation rate of individual droplets is impossible to discern. Flow cytometry is a technique for studying individual cells and their subpopulations using fluorescence technologies. It is possible that individual emulsion droplets could also be characterized by flow cytometry as a novel approach for studying lipid oxidation. Typical emulsion droplets are too small to be visualized by flow cytometer, so emulsions were prepared to have droplets > 2 μm; weighting agent and xanthan gum were added …
The Efficacy Of Atp Monitoring Devices At Measuring Organic Matter On Postharvest Surfaces, Kristin Lane
The Efficacy Of Atp Monitoring Devices At Measuring Organic Matter On Postharvest Surfaces, Kristin Lane
Masters Theses
The Food Safety Modernization Act (FSMA), specifically the Produce Safety Rule (PSR), requires growers to clean and sanitize food-contact surfaces to protect against produce contamination. The ATP monitoring device is a potential sanitation tool to monitor the efficacy of an on-farm cleaning and sanitation program that could help growers meet regulatory expectations mandated by PSR. The ATP device uses bioluminescence to detect all ATP (found in bacteria and produce matter cells) from a swabbed surface. Little work has been done to test the efficacy of these tools under postharvest conditions. The present study evaluated ATP measurement for postharvest surface cleanliness …
Optical Meets Mechanical: Use Of Luminescence Spectroscopy To Assess Ageing In Biodegradable Films, Louis Colaruotolo
Optical Meets Mechanical: Use Of Luminescence Spectroscopy To Assess Ageing In Biodegradable Films, Louis Colaruotolo
Masters Theses
With the growing concern of the accumulation of plastic-based food packaging waste, the search for bio-based biodegradable packages is on the rise. These materials differ from their petro-based counterparts in their degradation rates, which are much higher in the former. Not only do bio-based biodegradable materials degrade faster during post-usage processes but also they age faster during usage and storage, which affects their performance and functionality. The application of noninvasive testing methods with the capability to report on the matrix’s state could assist in the development of a more ubiquitous way to assess ageing in food packaging, particularly in biodegradable …
Development Of Colloids-Based Food Delivery Systems To Enhance The Beneficial Effects Of Nutraceuticals For Human Health, Zipei Zhang
Doctoral Dissertations
In current studies, hydrogel particles were formed by polysaccharides (i.e., alginate or pectin) and protein (i.e., casein or gelatin) through complex coacervation. Our results indicated that the encapsulation of protein or polyunsaturated lipid droplets nanoparticles within the hydrogel particles could improve their chemical or physical stability during storage. The lipid droplets encapsulated within the hydrogel particles could be released under simulated oral conditions, which was triggered by a pH or temperature change. The current study further fabricated the hydrogel particles (beads) using alginate or carrageenan based on an injection-gelation method. We found carrageenan beads had a relatively fragile structure that …
Determining Kinetic Parameters Of Thiamine Degradation In Three Nasa Spaceflight Foods In Thermal Processing And Long-Term Storage And Methods For Analyzing Microstructure And Precipitant Development In Real And Model Wines, Timothy R. Goulette
Doctoral Dissertations
The current NASA spaceflight food program encompasses a wide variety of commercial and custom-made edible products. These foods are designed to ensure each crewmember receives the Recommended Dietary Allowance (RDA) of vitamins and minerals to maintain adequate health during the entire spaceflight mission. With the desire for long-duration and exploration-class missions, such as the impending mission to Mars, the retention of important nutrients such as labile vitamins in spaceflight foods is critically important. For this reason, multiple studies were conducted to determine the vitamin degradation behavior of thiamine (vitamin B1) within three spaceflight foods which demonstrated both significant …
The Bioactive Effects Of Chicoric Acid As A Functional Food Ingredient, Ye Peng
The Bioactive Effects Of Chicoric Acid As A Functional Food Ingredient, Ye Peng
Doctoral Dissertations
Chicoric acid, a hydroxycinnamic acid, has been reported to possess a variety of health benefits, including antivirus, anti-oxidation, anti-inflammation, obesity prevention and neuroprotection effects. However, its role on aging and glucose homeostasis are largely unknown. Therefore, the bioactive effects of chicoric acid on aging and glucose homeostasis were determined using Caenorhabditis elegans (C. elegans) and C2C12 myotubes, respectively. Our study showed that chicoric acid (25 and 50 µM) significantly extended the lifespan of C. elegans and increased median survival rates. The declines of pumping rate and locomotive activity, two indicators of aging, were delayed by chicoric acid. Chicoric …
Hybridized Polymeric Nano-Assemblies: Key Insights Into Addressing Mdr Infections, Ryan Landis
Hybridized Polymeric Nano-Assemblies: Key Insights Into Addressing Mdr Infections, Ryan Landis
Doctoral Dissertations
Multidrug-resistant (MDR) bacteria contribute to more than 700,000 annual deaths world-wide. Millions more suffer from limb amputations or face high healthcare treatment costs where prolonged and costly therapeutic regimens are used to counter MDR infections. While there is an international push to develop novel and more powerful antimicrobials to address the impending threat, one particularly interesting approach that has re-emerged are essential oils, phytochemical extracts derived from plant sources. While their antimicrobial activity demonstrates a promising avenue, their stability in aqueous media, limits their practical use in or on mammals. Inspired by the versatility of polymer nanotechnology and the sustainability …
Strategies To Increase Lipid Oxidative Stability Of A Low Moisture Cracker System, Thanh Vu
Strategies To Increase Lipid Oxidative Stability Of A Low Moisture Cracker System, Thanh Vu
Doctoral Dissertations
The first study focuses on impact of solid fat content (SFC) on lipid oxidation and micro-structure of low moisture crackers. A series of fats were formulated to have varying SFC but the same linoleic acid (18:2) and tocopherol compositions so the fats had similar susceptibility to oxidation. A comparison of the oxidative stability of interesterified soybean oil and a blend of fully hydrogenated soybean fat and soybean oil, the interesterified fat (13.7% SFC at 55 oC) resulted in a more oxidatively stable cracker than the fat blend (17.4% SFC at 55 oC). Similarly in crackers were made from …
Prediction And Control Of Vitamin C Loss In Spaceflight Foods, William Dixon
Prediction And Control Of Vitamin C Loss In Spaceflight Foods, William Dixon
Doctoral Dissertations
Shelf stable foods that require no refrigeration or freezing are the predominant food source for astronauts. Due to its high impact on astronauts’ health, it is crucial to know if the astronauts are getting all the necessary nutrients from shelf stable foods, specifically vitamins. With limited knowledge on vitamin degradation in spaceflight foods during storage and processing, our team decided to tackle this issue focusing on unstable vitamins, which included vitamin C (ascorbic acid) and vitamin B1 (thiamine); however, this thesis will specifically focus on vitamin C. A two-year storage and retort processing study was conducted on 5 different foods …
Influence Of Shipping Container Upon Temperature, Relative Humidity, And Bacterial Growth On Broccoli, Nicholas Berus
Influence Of Shipping Container Upon Temperature, Relative Humidity, And Bacterial Growth On Broccoli, Nicholas Berus
Masters Theses
Temperature and relative humidity of produce throughout the cold chain can greatly affect the quality and safety of the food product. Different packaging systems or containers can provide better cooling environments for food products that could decrease temperature abuse and ultimately safety risks. In this study we compiled temperature and relative humidity profiles of broccoli packed in different shipping containers throughout the produce supply chain. The shipping containers looked at were the wax corrugated box, reusable plastic containers (RPC), and Eco Pack Green Box with and without a lid. Large differences were seen in the temperature profiles of each package …