Digital Commons Network^™

Amyloid Aggregation-Mitigating Peptides As Potential Alzheimer's Drugs, Cyrus Kipkurui Bett

LSU Doctoral Dissertations

Neuronal cytotoxicity observed in Alzheimer¡¦s disease (AD) is linked to the aggregation of £]-amyloid peptide (A£]) into toxic forms. Increasing evidence points to oligomeric species as the neurotoxic species compared to fibrils; disruption or inhibition of A£]ƒnself-assembly into oligomeric or fibrillar forms remains a viable therapeutic strategy to reduce A£] neurotoxicity. Amyloid aggregation mitigating peptides (AAMPs) were designed based on the A£]ƒn¡§hydrophobic core¡¨ A£]17-20, with C£\,£\-disubstituted amino acidsƒnƒv£\£\AAs) added into this core as disrupting agents. The number, distribution, and side chain functionality of £\£\AAs incorporated into the mitigator sequence was found influences the resultant aggregate morphology as indicated by ex-situ …

Collpas As Activity Hotspots For Frugivorous Bats (Stenodermatinae) In The Peruvian Amazon: Underlying Mechanisms And Conservation Implications, Adriana Bravo Ordonez

LSU Doctoral Dissertations

In western Amazonia, large numbers of frugivorous bats regularly visit natural forest clearings known locally as collpas (also called clay licks or mineral licks). Bats arrive at collpas to drink water that has accumulated in depressions created by larger mammals that consume soil. Although collpa visitation by bats appears relatively common in western Amazonia, little is known about its causes and its ecological implications. In this dissertation I describe general and seasonal patterns of collpa visitation by frugivorous bats in the Peruvian Amazon, and I investigate potential explanations for this unique behavior. Regardless of season, collpas seem to be activity …

Determination Of Minimum Safe Cooking Temperatures For Shrimp To Destroy Foodborne Pathogens, Sailaja Chintagari

LSU Master's Theses

Shrimp is one of the most common seafoods and a favorite among consumers. Like any other food there are safety concerns about shrimp. Listeria species, Salmonella species, Clostridium species and Vibrio species are among the pathogens of prime importance. Most of these pathogens can be eliminated by cooking. However, the extent of cooking and temperatures greatly influence the safety of these foods. The current study is focused on the determination of minimum cooking temperatures for shrimp to eliminate Listeria species, Salmonella species and Vibrio species. Shrimp were surface inoculated with the three different species mentioned above to about 5.00 log …

Numerical Modeling For Long Term Performance Of Soil-Bentonite Cut-Off Walls In Unsaturated Soil Zone, Sukanta Chakraborty

LSU Master's Theses

ABSTRACT The construction practices of containment walls are extremely important in this competitive economic market, but development is limited. Unsaturated zone is an integral part of the geotechnical problems, as it affects on any kind of soils structures. The unsaturated zone plays significant role in many aspects of water flow and contaminant transport, including containment system such as: cut-off walls, infiltration, soil moisture storage, evaporation, plant water uptake, ground water recharge, erosion, and runoff. This research focuses on the hydraulic sustainability and performance of soil-bentonite cutoff walls (Britton et al, 2004) models showing hydraulic behavior of barrier walls. The cutoff …

Dynamic Behavior Of Unsaturated Soils, Prathima Alla

LSU Master's Theses

The behavior of unsaturated soils is different from the behavior of saturated soil deposits. Unsaturated soils have more than two phases; the pore water pressure in unsaturated soils is negative. The behavior of unsaturated soil when a dynamic loading such as an earthquake loading is imposed on them, the susceptibility of lab tested soils to liquefaction is investigated in this study. As the phenomenon of liquefaction occurs only in the case of saturated soil deposits, the behavior of unsaturated soil under these conditions is investigated. Sand and silty sand are used in this study, wetting and drying soil water characteristic …

Modification Of Rice Starch Properties By Addition Of Amino Acids At Various Ph Levels, Rosaly Vallejo Manaois

LSU Master's Theses

Amino acids were previously found to modify starch functionalities and potentially increase starch utilization. The effect of amino acids at different pH levels on the pasting properties, thermal characteristics, and resistant starch (RS) formation of rice starch was investigated. Prior to the analyses, pretreatment of starch was done by adding amino acid (aspartic acid, leucine, lysine and tyrosine) at 6% dry weight basis and dispersing the mixture in distilled water, solutions adjusted with HCl and NaOH to pH 4, 7 and 10, and buffers of acetate, phosphate and carbonate at the same pH levels, respectively. Samples in HCl/NaOH solutions were …

Testicular Toxicity And The Potential For 1, 2 -Ethlyene Dichloride (Edc) To Initiate Epigenetic Disruption Of The Paternal Genome, Harold J. Daigle

LSU Doctoral Dissertations

Our genetic inheritance begins with one genome copy from each parent. The presence of one or more errors in either the maternal or the paternal genome can lead to genetic disease or disruption of the embryonic program and potential loss of the offspring. Numerous chemical and physical toxicants are known to produce germ line mutagenesis based on their ability to produce DNA sequence mutations. Exposures to these cytotoxic and mutagenic agents pose a risk for human offspring. However, very little is known regarding the sensitivity of the epigenetic patterns involved in reproductive functions to adverse effects of chemical agents. The …

Investigations Of Chlamydomonas Reinhardtii Ergosterol Biosynthesis, Kristy Marie Brumfield

LSU Doctoral Dissertations

Ergosterol is the major sterol found in the membranes of Chlamydomonas reinhardtii. While past studies have identified some ergosterol mutants in C. reinhardtii, very little is known about sterol biosynthesis pathways in this species. With the elucidation of the Chlamydomonas genome, bioinformatics analysis has allowed us to determine potential genes involved in ergosterol biosynthesis. With this knowledge, a working model of the pathway was designed for future analysis. Several of the ergosterol biosynthetic genes were analyzed in respect to their role and involvement in flagellar regeneration. These genes were upregulated during the regrowth of the flagella. Also Chlamydomonas strains lacking …

Atomistic Simulations Of Lipid Bilayers In The Presence Of Dimethylsulfoxide, Raghava Alapati

LSU Master's Theses

In a typical cryopreservation protocol, the system to be preserved is first equilibrated with chemicals known as cryoprotective agents (CPAs). CPAs have been shown to alleviate cell damage from either the solute effects or the formation of intracellular ice during the subsequent freezing process. Thus, an extensive body of literature reporting the effects of CPAs on cellular systems has been accumulated over the last 50 years; detailing largely experimental interactions between cell systems and chemicals. Recent advances in computational methodology now offer an additional dimension in our ability to understand the molecular interactions between cell membranes, idealized as lipid bilayers …

Phytochemical Analyses Of Bioactive Compounds In The Roots Of Cassia Alata Linn And The Anti-Angiogenic Evaluation Of Rhein As A Therapeutic Agent Against Breast Cancer Cells, Vivian Esther Fernand

LSU Doctoral Dissertations

The research presented in this dissertation includes the novel phytochemical analysis of root extracts of Cassia alata L. and the anti-angiogenic evaluation of rhein in the treatment of breast cancer. To conduct these studies a combination of analytical techniques were employed, namely, chromatographic, spectroscopic, and bioanalytical. The first part of this research is focused on the phytochemical analysis of C. alata root extracts. A high performance liquid chromatography method was developed and validated for the determination of six phenolic compounds in the root extracts. The investigated compounds were identified by their ultraviolet spectra. Additionally, the presence of these phenolics was …

Polyunsaturated Fatty Acid Content Of Breast Milk From Women With And Without Gestational Diabetes Mellitus, Julissa Marisel Salguero

LSU Master's Theses

Reduced insulin sensitivity and abnormal nutrient metabolism in gestational diabetes mellitus (GDM) may compromise polyunsaturated fatty acid (PUFA) content of breast milk. The purpose of the present study was to evaluate and compare PUFA milk composition of women with and without GDM. Breast milk collections were performed in GDM (n=6) and controls (n=12) at weeks 2, 6, 10 and 12 postpartum using a hospital grade breast pump. Estimated dietary intake of PUFA and use of prenatal supplements containing DHA (PS/DHA) was determined by 24-hour dietary recalls conducted after each milk collection. Based on these preliminary data, milk docosahexaenoic acid (DHA; …

Physical And Chemical Factors Controlling Carbon Gas Emissions And Organic Matter Transformation In Coastal Wetlands, Syam Kumar Dodla

LSU Doctoral Dissertations

Wetlands are important sinks for the atmospheric carbon (C) and play a major role in the global carbon cycle. However, factors impacting wetland soil C transformations and C gas production are not yet well understood. Elucidating these influences is especially important to Louisiana as wetlands are being impacted by salt water intrusion, subsidence and Mississippi river water diversion activities. This study evaluates, the effects of salinity, ions in river and sea water (K+, Ca2+) , clays and electron acceptors (NO3-, SO42-) on soil C transformations as well as C gas production from Louisiana coastal wetlands. Wetland soils were collected from …

Antiviral Chemotherapeutic Agents Against Equine Herpesvirus Type 1: The Mechanism Of Antiviral Effects Of Porphyrin Derivatives, Galena V. Rybachuk

LSU Doctoral Dissertations

Equine Herpesvirus-1 (EHV-1) is an important ubiquitous enzootic equine pathogen, causing significant economic losses to the horse industry. Despite extensive vaccination protocols, EHV-1 continues to be a major cause of epidemic abortion, perinatal mortality, respiratory disease and neurologic disease. EHV-1 infections are usually dealt with by using management practices that limit spread of the disease and secondary complications, providing symptomatic relief to infected horses, but no specific treatment is available. New therapeutic or virucidal agents could have great utility in slowing both the progression and spread of the disease in an epidemic situation. A number of porphyrins and their derivatives …

The Effects Of Geomorphology And Primary Productivity On Neotropical Leaf Litter Herpetofauna: Implications For Amazonian Rainforest Conservation, Jessica L. Deichmann

LSU Doctoral Dissertations

The Amazon rainforest encompasses over one billion acres of South America and sustains remarkable biodiversity. Despite the large body of research stemming from this region, little is known about the effects of geomorphology and primary productivity on the fauna of Amazonia, and on reptiles and amphibians in particular. In my dissertation, I examine differences in the abundance, biomass and species richness of secondary consumers in the leaf litter herpetofauna communities on young and ancient soils. Herein, I develop methods to utilize existing data sets and museum collections in new studies involving community biomass. I found that, although the process of …

The Role Of Climate Variability And Riverine Pulsing In The Community Dynamics Of Estuarine Nekton In Breton Sound, Louisiana, Bryan Patrick Piazza

LSU Doctoral Dissertations

Climate controls biotic community composition at multiple spatiotemporal scales through variability in environmental control mechanisms (assembly filters). This research investigated the role of climate variability in the community dynamics of estuarine nekton in Breton Sound estuary, Louisiana, and, specifically the effects of El Niño Southern Oscillation (ENSO), freshwater discharge, and a tropical cyclone. A teleconnection was found between ENSO and juvenile brown shrimp (Farfantepenaeus aztecus) abundance in Breton Sound from 1988 – 2007. ENSO affected winter weather conditions (air pressure, temperature and precipitation), and spring brown shrimp abundance in Breton Sound. Juvenile brown shrimp abundance lagged ENSO by …

Apolipoprotein Status And Cognitive Functioning In Adulthood: Role Of Physical Health And Social Network Characteristics, Jennifer Lee Silva

LSU Doctoral Dissertations

This study examined the relationships among cognitive function, physical health, social network characteristics, and apolipoprotein (APOE) genotype in participants from the Louisiana Healthy Aging Study. Prior literature has shown that the ε4 allele of APOE is associated with cognitive deficits (Wisdom, Callahan, & Hawkins, 2009). This study failed to find any relation between APOE genotype (ε4 carrier vs. non-carrier) and cognitive ability after controlling for age and education level. Tests for physical health mediation and social network moderation did not alter the ε4/cognition null results. This finding conflicts with prior research suggesting that physical activity and health modify the association …

Gender Differences In Children With Autism Spectrum Disorders And Comorbid Psychopathology, Julie Hess

LSU Master's Theses

Abstract Children and adolescents diagnosed with Autism Spectrum Disorders (ASD) frequently exhibit symptoms that are not associated with the core features of ASD. These symptoms may meet criteria for an additional diagnosis; however, accurate assessment of comorbid psychiatric conditions in ASD has been hindered by a lack of measures designed for this specific purpose. The newly constructed assessment measure, Autism Spectrum Disorders-Comorbid for Children (ASD-CC) has been developed specifically for examining comorbid psychiatric disorders in ASD. Therefore, this study set out to assess differences in the endorsement rates of psychiatric symptoms in children and adolescents diagnosed with ASD compared to …

Parallel Cloth Simulation Using Openmp And Cuda, Gillian David Sims

LSU Doctoral Dissertations

The widespread availability of parallel computing architectures has lead to research regarding algorithms and techniques that best exploit available parallelism. In addition to the CPU parallelism available; the GPU has emerged as a parallel computational device. The goal of this study was to explore the combined use of CPU and GPU parallelism by developing a hybrid parallel CPU/GPU cloth simulation application. In order to evaluate the benefits of the hybrid approach, the application was first developed in sequential CPU form, followed by a parallel CPU form. The application uses Backward Euler implicit time integration to solve the differential equations of …

Furthering Pharmacological And Physiological Assessment Of The Glutamatergic Receptors At The Drosophila Neuromuscular Junction, Junyoung Lee

University of Kentucky Master's Theses

Drosophila larval neuromuscular junctions (NMJs) serve as a model for synaptic physiology. The molecular sequence of the postsynaptic glutamate receptors has been described; however, the pharmacological profile has not been fully elucidated. Despite the postsynaptic molecular sequence used to classify the receptors as a kainate subtype, they do not respond pharmacologically as such. Kainate does not depolarize the muscle, but dampens evoked EPSP amplitudes. Quantal responses show a decreased amplitude and area under the voltage curve indicative of reduced postsynaptic receptor sensitivity to glutamate transmission. ATPA, a kainate receptor agonist, did not mimic kainate’s action. The metabotropic glutamate receptor agonist …

Evaluation Of Dietary Alterations That Have Potential To Affect Feed Intake And Feed Preference In Swine, James Seth Monegue

University of Kentucky Master's Theses

Feed intake is a key factor affecting pig performance; thus, the objective of these studies was to assess a variety of factors that could potentially affect intake in pigs in different production stages. Studies were conducted to determine the effects of flavor and diet complexity, Appetein™ (an alternative protein source), and graded levels of salt on swine feed intake and feed preference. Two newly developed flavors were used in nursery pig diets. The use of the two flavors did not increase feed intake (P > 0.05). Nursery pigs actually showed a preference for the control diet. Complex diet formulation does increase …

Cbod₅ Treatment And Nitrogen Transformations Of The Marshland Upwelling System In Intermediate And Saltwater Marshes, Lorna Anne Putnam

LSU Doctoral Dissertations

The marshland upwelling system (MUS) was designed to treat domestic wastewater from coastal dwellings where conventional methods are inadequate due to high water tables, poor hydraulic soil conditions, anaerobic soils, and saline groundwater. Currently there is no adequate treatment system available and coastal dwellings are contributing to water quality problems. This study focused on determining the treatment effectiveness of the MUS for organic matter and understanding the specific processes involved in nitrogen treatment.

The treatment of organic matter, measured as five-day carbonaceous biological oxygen demand (CBOD₅), was effective in field tests for both saltwater and intermediate marshes. Global …

Characterization Of The 'Glutamate Effect' On The Solution Thermodynamics And Function Of The Large Fragments Of The Type I Dna Polymerases From E.Coli And T.Aquaticus, Daniel J. Deredge

LSU Doctoral Dissertations

In this study, it is shown that the large fragments of the type I DNA polymerase from E.coli (Klenow) and T.aquaticus (Klentaq) display enhanced DNA binding affinity in glutamate vs. chloride. Across the relatively narrow salt concentration ranges often used to obtain salt linkage data, Klenow also displays an apparently decreased linked ion released (¦¤n_ions) in Kglutamate vs. KCl while Klentaq does not display such an effect. The osmotic stress technique reveals that Klenow and Klentaq DNA binding is associated with the release of ~500 to 600 waters in KCl. For both proteins, replacing chloride with glutamate results …

Distribution, Diversity And Ecology Of Aerobic Carbon Monoxide-Oxidizing Bacteria In Hawaiian Volcanic Deposits, Carolyn Frances Weber

LSU Doctoral Dissertations

Carbon monoxide-oxidizing bacteria are among the first colonists of recently formed volcanic deposits despite environmental conditions that challenge their survival, such as oscillating water regimes and lack of endogenous sources of organic carbon and nitrogen. Activity assessments and molecular surveys of the coxL gene (large subunit carbon monoxide dehydrogenase) across a vegetation gradient on a 1959 volcanic deposit on Kilauea Volcano (Hawai’i) indicated that CO-oxidizing communities continue to expand, diversify and remain competitive during ecosystem development. Distinct compositional shifts occurred across the gradient with Firmicutes-like coxL sequences dominating clone libraries from unvegetated sites (Bare) and Proteobacteria coxL sequences dominating libraries …

Studies On The Effect Of Natural Organic Matter And Hydration On The Sorption And Desorption Of Trifluorinated Pesticides, Charisma Vinarao Lattao

LSU Doctoral Dissertations

This work was done in order to deepen our molecular level understanding of how soil organic matter (SOM) is assembled in a whole soil and to provide further insight on the effect of SOM assembly on the uptake and release of hydrophobic organic compounds. Various techniques, including ultraviolet absorbance, fluorescence, and total carbon analysis, demonstrate that hydration/solvation of SOM is kinetically controlled. Initial wetting of a soil releases the hydrophobic moieties that are located at the outer surface of SOM, and longer wetting times exfoliate more hydrophobic quinone type moieties that are present in the middle layer, which in turn …

A Mineral Survey Of Louisiana Beef Cow/Calf Production Systems, Kyle Austin Guidry

LSU Master's Theses

The purpose of this research was to determine the state and regional mineral status of Louisiana forages and beef cattle. Louisiana beef cattle operations (n = 25) were sampled and divided into seven geographical regions, including the northwest (NW), northeast (NE), central (CE), southwest (SW), south central (SC), Florida parishes (FP) and southeast (SE) regions. Over a two year period, water and soil samples were collected from each operation annually, forage samples were collected quarterly in Aug to Sep, Nov to Dec, Feb to Mar and May to June and bovine serum samples were collected twice annually in the fall …

Role Of Shelf Morphology In Grounding-Line Stability: A Numerical Approach, Rhonika Robinson

LSU Master's Theses

The main concern of this study is to discover how the transition from a shallow to an overdeepened, foredeepened shelf might affect grounding-line translation of the West Antarctic Ice Sheet (WAIS). Deep shelves permit a larger influx of relatively warm Circumpolar Deep Water (CDW), which melts the ice at grounding lines, and thereby, create a potentially unstable situation in which ice retreat may accelerate. Numerical analysis of the responses of marine ice sheets on various shelf profiles confirmed that a change in shelf morphology changes ice sheet dynamics. Ice sheet retreat on an overdeepened, foredeepened shelf is, at least, 3 …

Size Controlled Metal Oxide Nanoparticles:Synthesis, Characterization, And Application To Catalysis, Hongyi Wu

LSU Doctoral Dissertations

The research in this dissertation focuses on the synthesis of size-controlled metal oxide nanoclusters (< 10 nm) on amorphous silica and their catalytic performance in thermal degradation of chlorinated benzenes with regard to the cluster size effect. Furthermore, with the concern that metal can condense as the nano-size nuclei core for particle growth in combustion process, a flow reactor was built to investigate the effect of metal oxide nanoparticles on the formation of soot in fuel-rich combustion. The synthesis of copper oxide nanoclusters was carried by calcination of silica impregnated with dendrimer-metal complexes. The 4th generation poly(propylene imine) dendrimer DAB-Am32 was used in this template-based method. The sizes of copper oxide nanoclusters were exquisitely controlled in the range of 1-5 nm with narrow size distribution by changing the stoichiometric ratio of metal ion to the terminal primary amines of dendrimer, the equivalent metal oxide loading on surface, and the impregnation procedure. XANES and XPS studies revealed that CuO was the dominant component of copper oxide nanoclusters. This method was also experimentally proven to be valid in the preparation of other metal oxide nanoparticles, e.g., Ni and Fe, and with other oxide substrates, e.g., titanium oxide. Chlorinated benzenes were selected as the model compound for studying the activity of metal (Cu and Fe) oxide catalysts with regard to their cluster sizes. Compared to the surrogate of coarse metal oxide samples, which was prepared by incipient wetness method, their nanosize analogues showed superior catalytic activity on the conversion of chlorinated benzenes under both pyrolytic and oxidative thermal condition. Furthermore, such catalytic size effect was also observed on the selectivity of products yields. Sooting combustion was performed using a two-zone flow reactor with precise control on experimental parameters. Gas suspended metal oxide nanoparticles were generated by burning off the organic backbone of the dendrimer-metal complexes in zone 1 and immediately transferred to zone 2, where the hydrocarbon combustion occurred. TEM results of the particulate sample collected at the outlet of reactor indicated that metal oxide nanoparticles promoted soot formation. GC/MS analysis of the extracted organic materials from soot samples suggested the formation of PAH was also promoted by metal addition as well.

Functional Implications Of The Neuromuscular Transform In Decapod Crustacean Locomotion, Richard Burkett Dewell

LSU Doctoral Dissertations

All animals face the same basic challenges in controling movement through their environment. The central nervous system must activate and effectively control muscle fibers capable of accomplishing the behavior. For multi functional muscles, an array of muscle fiber types must be selectively activated based on the behavioral task. In arthropods that have few motor neurons, it is not understod how the nervous system accomplishes this selective activation. If the selection cannot be achieved by recruitment of different motor neurons, then it most likely results from careful adjustment to the firing patterns of the motor neurons. I used the neuromuscular system …

Achiral, Chiral, And Protein Separations With Molecular Micelles Using Chromatographic Techniques, Candace Ayanna Luces

LSU Doctoral Dissertations

In this dissertation, several chromatographic techniques were developed for separation of proteins as well as achiral and chiral compounds. Firstly, polyelectrolyte multilayer (PEM) coatings were used to separate chiral analytes and proteins of pharmaceutical and biomedical interests. Coating polymers used in PEM coatings are instrumental in analyte separation. Therefore, the effect of changing four different cationic polymers, (poly-L-lysine, poly-L-ornithine, poly-L-lysine-serine, and poly-L-glutamic acid-lysine) and three anionic polymers (sodium poly (N-undecanoyl-L-leucyl-alaninate) (poly-L-SULA), sodium poly (N-undecanoyl-L-leucyl-valinate) (poly-L-SULV) and sodium poly (undecylenic sulfate) (poly-SUS)) were investigated. The simultaneous effects of cationic polymer concentration, number of bilayers, temperature, applied voltage, and pH of the …

Computational Studies On Fatty Acid Synthesis: From Mechanisms To Drug Design, Matthew Edward Mckenzie

LSU Doctoral Dissertations

The first committed steps of the Fatty Acid synthesis pathway involves the de/carboxylation reactions of biotin. By understanding this step, potential novel antimicrobial agents could be discovered. The current tools of drug discovery can only help the research in finding and modifying potential hits. Finding a lead candidate from these programs are often equated to finding a needle in a haystack, which is due to the many assumptions used in molecular docking. The fundamental reaction kinetics can not be described by these techniques and a detailed study of the decarboxylation reaction is investigated using ab initio molecular dynamics. In this …