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Producing In-Situ Nanoparticles Of Griseofulvin Using Supercritical Antisolvent Methodology, Pratik Sheth

Open Access Dissertations

Poor aqueous solubility of drug candidates is a major challenge for the pharmaceutical scientists involved in drug development. Particle size reduction to nano scale appears as an effective and versatile option for solubility improvement. Unlike the traditional methods used for the particle size reduction, supercritical fluid (SCF) processing techniques offer advantages ranging from superior particle size control to clean processing. Amongst all of the SCF based techniques, supercritical antisolvent (SAS) processing is of particular interest because most pharmaceuticals, including the model drug for this study-griseofulvin, are insoluble in supercritical carbon dioxide (scCO₂), and SAS is one of the …

Physical Properties Of Marine Sediments And Their Application Toward Climate Change Studies, Tania Lado Insua

Open Access Dissertations

The Integrated Ocean Drilling Program (IODP) is the world’s largest collaborative research initiative for the study of the ocean seafloor, subseafloor, and their application to earth system science. The processing of recovered cores from the subseafloor by IODP has been standardized to maintain constant, reproducible results and to make the measurements available to the scientific community using a worldwide- web based database. The study of physical properties is a basic requirement for the study of marine sediments as they form a foundation data set for most of earth system dynamic studies.

This thesis focuses on solving four different scientific problems …

Asleep Behind The Wheel: Experiences Of Night Shift Nurses On The Commute Home, Shirley A. Sargent

Open Access Dissertations

Aim: The aim of this study was to obtain descriptions of nurses’ perceptions and experiences of falling asleep behind the wheel on the drive home after a worked night shift.

Background: While the evidence suggests that the problem of drowsy driving and fall asleep driving is a strong contributor to vehicular accidents, little is known about nursing perceptions of the issue.

Methods: The design of the study is qualitative and descriptive. Face-to-face interviews were conducted with 12 registered nurses who had experienced falling asleep behind the wheel on the drive home from work after a worked night shift. The interviews …

Prediction Of Heptatic And Renal Clearance In Pediatric Populations: A "Bottom-Up" Approach Versus "Top-Down" Recognition Of Covariates, Hong Lu

Open Access Dissertations

Medications, including many that are widely used in children, are rarely tested in children. Their safety and effectiveness have not been established in children or have been established only for children of a certain ages. For example, 53 of 140 new medications were labeled for use in children when they were initially approved. Much of pediatric practice, particularly in hospitals and by specialists, has involved "off-label" use of medications. As a consequence, about one-third of the drugs prescribed in office-based pediatric practices and about two-thirds of those prescribed to children in hospital settings are unlicensed or off-label. This proportion reaches …

A Comparison Of Carbonic Anhydrase Among Invertebrates, With A Focus On Cephalopods, Albert C. Nyack

Open Access Dissertations

Carbon dioxide (CO₂) is both an unavoidable waste product of aerobic carbohydrate metabolism and a fuel source for autotrophic and chemoautotrophic organisms. At biological pH, CO₂ rapidly reacts with interstitial and intracellular water to form carbonic acid (H₂CO₃), that then dissociates into protons (H⁺) and bicarbonate (HCO₃^-). While CO₂ and H⁺ readily diffuse across biological membranes, the majority of the CO₂ in living tissues is in the membrane-impermeable form HCO₃^-. The enzyme carbonic anhydrase (CA) catalyzes the reversible hydration of CO_{2 …}

Trophic Ecology Of Oxygen Minimum Zone Zooplankton Revealed By Carbon And Nitrogen Stable Isotopes, Rebecca Williams

Open Access Dissertations

Oxygen minimum zones (OMZs) are areas in which midwater oxygen concentration can be significantly lower than in non OMZ areas at comparable depths. OMZs are of great interest because of the limits oxygen availability places on life. The potential for OMZ expansion with warming of the oceans has refocused attention on the importance of these areas and their potential impacts on the global carbon cycle. The large open ocean OMZs of the Eastern Tropical Pacific and Arabian Sea are notable for their size, thickness, and the intensity of oxygen depletion (

Here, I use measurements of natural abundance carbon and …

An In Vitro Study On The Non-Enzymatic Glycation Of Melamine And Serum Albumin By Reducing Sugars, Weixi Liu

Open Access Dissertations

Glycation is a non-enzymatic reaction with reactants including a reducing sugar and a free amino containing molecule such as protein, amino acids, DNA, RNA and lipids. In the initial phase of glycation, the carbonyl group of the reducing carbohydrate condenses with the free amino groups on the target biomolecule to form reversible glycosylamines, which are then converted to more stable Amadori products. Once formed, these Amadori products can with time undergo dehydration, cyclization, oxidation, and rearrangement to form a polymorphic group of compounds collectively referred to as Advanced Glycation Endproducts (AGEs). The accumulation of AGEs in vivo has been implicated …

Role Of Deg/Enac Channels Expressed In Glia In C. Elegans Touch Sensitivity, Lu Han

Open Access Dissertations

Neuronal DEG/ENaC Na+ channels have been implicated in touch sensation. For example, MEC-4 is expressed in touch neurons in C. elegans and mediates gentle touch response. Similarly, homologous mammalian ASIC2 and ASIC3 are expressed in sensory neurons and produce touch phenotypes when knocked out in mice. Here, we show that novel DEG/ENaC subunits DELM-1 and DELM-2 are expressed in glia associated with touch neurons in C. elegans and that their knock-out causes defects in mechanosensory behaviors related to nose touch and foraging, which are mediated by OLQ and IL1 sensory neurons. Cell-specific rescue supports the idea that DELM-1 and DELM-2 …

Donor T Cell Outcome And Immune Reconstitution Following Post-Transplant Cyclophosphamide And Regulatory T Cell Therapy In Recipients Of Mhc Matched Allogeneic Hematopoietic Stem Cell Transplants, Duncan B. Ross Iii

Open Access Dissertations

Blood cancers result in the deaths of over 50,000 patients worldwide annually. While capable of inducing temporary or occasionally complete remissions in patients with favorable cytogenetics, conventional chemotherapy is limited both by its toxicity and lack of specificity, often causing secondary disease years later. For over 50 years, the techniques of transplantation have been developed through the complicated interpretation of biology and countless lives. Today, developments in the field of hematopoietic stem cell transplantation have led to an increasing use of the therapy in patients of all ages. The main deterrent to the use of transplantation today is the divergent …

Wnt Signaling In The Cnidarian Nematostella Vectensis: Insighits Into The Evolution Of Gastrulation, Naveen M. Wijesena

Open Access Dissertations

The genesis of gastrulation was arguably a key evolutionary innovation that enabled metazoan diversification. The developmental mechanisms that induced archenteron formation and endodermal cell fate specification during gastrulation are unknown, but one crucial step was likely the co-option of a localized molecular asymmetry that was present in ancient embryos. One ancient polarity present in most metazoan eggs is the animal vegetal (AV) or primary egg axis, which is established by the asymmetric localization of maternal factors such as RNA, proteins and organelles during oogenesis. In bilaterians, which account for a majority of animal taxa, the AV axis predicts the axial …

Characterization Of The Phenotypic Differences Between Wild Type And Effector Caspase Deficient Mouse Embryonic Fibroblasts, Matthew R. Brentnall

Open Access Dissertations

The caspase family of proteins consists of upstream initiator caspases that activate downstream effector caspases, which are responsible for the proteolytic cleavage of many hundreds of proteins during apoptosis. Caspases 7 and 3 cleave a variety of proteins that lead to the hallmarks of apoptosis including, nuclear condensation, DNA fragmentation and membrane blebbing. Classically, caspase 7 and 3 were thought of as redundant because they share a 49.2 % amino acid sequence identity, a 62.0 % amino acid sequence similarity and have the same preferred cleavage motif (DEVD). However, recent data have demonstrated that caspase 7 and 3 are distinct …

Interactive Effects Of Water Flow And Light Levels With Decreasing Ph On The Growth And Survival Of Tropical Cnidarians, Carolyn L. Margolin

Open Access Dissertations

The changes in global climate, including the observed and predicted changes to ocean chemistry are expected to have significant impacts on the future of coral reefs. A series of laboratory experiments examined the interactive effects of water flow rate, light levels, and decreased pH on the growth of several species of reef cnidarians. Under current water chemistry conditions (pH 8.04), the massive coral species, Montastraea faveolata shows high growth under flow conditions less than 15.7 cm/s. At this flow rate, decreased pH (pH 7.88) had no significant impact on the growth of this species. Under both water chemistry conditions, colonies …

The Importance Of The Rare: The Role Of Background Symbiodinium In The Response Of Reef Corals To Environmental Change, Rachel N. Silverstein

Open Access Dissertations

Reef ecosystems throughout much of the tropics are predicted to decline in coral cover and diversity as a result of ongoing climate change (ocean acidification, temperature increases, sea level rise), disease, pollution, and overfishing. Corals may be able to respond to some of these stressors by associating with diverse algal symbionts (Symbiodinium spp.) which vary in their physiological traits and therefore expand corals’ realized niche space. This dissertation used high-sensitivity molecular techniques to investigate the presence and functional role of "background" or "rare" Symbiodinium, which occur at low abundance, and therefore may not be detected using standard molecular methods. First, …

Mechanisms Of Nmnat/Wlds Mediated Axon Protection, Brandon M. Kitay

Open Access Dissertations

Neurodegeneration is a hallmark of several inherited and acquired diseases of the nervous system. Though great attention in the past has been given to understanding and mitigating neuron loss in these diseases, efforts at targeting neuron cell body death pathways have yielded modest success in preventing or delaying disease onset. Often preceding neuronal death, axon degeneration is a common pathological feature of many neurodegenerative processes, and may therefore provide a therapeutic target upstream of neuronal loss. Though formerly believed to be a passive process, recent observations concerning the destruction of distal axons following transection, referred to as “Wallerian degeneration” (WD), …

Predictors Of Hiv/Aids Related Stigma And Discrimination Among Anglophone Caribbean Women, Kimberly A. Hires

Open Access Dissertations

The effects of the Human Immunodeficiency Virus (HIV) global epidemic continue to emerge decades after teh first wave of infection. One key aspect of the HIV epidemic that is significantly impacted by culture and knowledge of HIV transmission is stigma, specifically HIV/AIDS related stigma and discrimination (HASD). The Caribbean region has the second highest HIV prevalence rate in the world. In 2011, there were approximately 13,000 new infections and 10,000 AIDS related deaths among adults and children in the Caribbean. Three Anglophone nations significantly impacted by the HIV epidemic are Guyana, Trinidad and Tobago and Jamaica. HASD has been identified …

Measurement Of Seawater Ph: A Theoretical And Analytical Investigation, Jason F. Waters

Open Access Dissertations

The emission of anthropogenic carbon is leading to the influx of additional CO2 to the atmosphere and global ocean. While the flux of anthropogenic CO2 from the atmosphere to the ocean may be leading to the mitigation of global climate change, it is also leading to the decline of global ocean pH – a process referred to as Ocean Acidification. The net effects Ocean Acidification will have on physical, biogeochemical, and ecological processes are currently not well constrained, but there is significant research interest in evaluating the effects of decreased pH on ocean processes. Seawater pH is the essential measurement …

Regulators And Effectors Of Acetyltransferase P300 During Oxidative Stress, Heart Disease And Aging, Sumit Jain

Open Access Dissertations

The nuclear acetyltransferase p300 is a chromatin-modifying enzyme that facilitates gene transcription by modifying histone-DNA interactions and promoting the transcriptional activation properties of numerous transcription factors. p300 and its paralogue, CBP (CREB-binding protein) are implicated in a wide range of essential biological processes, however, the extent to which p300 has independent tissue- or signal-specific functions has been a matter of dispute. Here, I used gene targeting, gain-of-function and knockdown models to show that the myocardial response to oxidative stress is obligatorily dependent on the cellular availability of p300, and that this availability is dynamically modulated as part of an acute …

Water And Nutrient Uptake Of Deciduous And Evergreen Trees In A Dry Seasonal Forest: Interrelationship Between Root Structure And Leaf Phenology, Patrick Z. Ellsworth

Open Access Dissertations

Dry seasonal ecosystems are defined by a pronounced and consistent dry season, which reduces water availability in the dry season. Plants must adapt to water limitation in the dry season and high water availability during the wet season. In addition, the soil is nutrient-poor with the majority of nutrients concentrated in shallow soil. Considering the temporal drying of these layers, nutrient availability is dependent on the climatic conditions that govern water availability in the shallow soil. In this dissertation I address differences in fine root density, water source use, and nutrient uptake between deciduous and evergreen species in a dry …

Oxygen Isotope Signature Of Cellulose: Advances As A Climate Proxy, Patricia V. Ellsworth

Open Access Dissertations

Cellulose is a very stable structural molecule integrated in the incremental growth of tree rings, often used for paleoclimate reconstruction. As cellulose is synthesized it incorporates the oxygen isotopic signature of source (stem) and leaf water, which provide valuable information about climate such as precipitation and relative humidity. However, source and leaf water isotopic signatures can be masked by plant physiological and biochemical processes during cellulose synthesis. The biochemical interference does not occur equally in all the oxygen of the cellulose molecule. In Chapter 2, I compared the observed versus the reconstructed oxygen isotope ratios of stem water (δ18OSW) using …

Praying Hands: Influences Of Religiosity And Spirituality On Sexual Risk-Taking Among Black, College-Attending Emerging Adults, Tralonda C. Triplett

Open Access Dissertations

The Centers for Disease Control and Prevention have confirmed persistent disproportionate burdens of HIV/AIDS among Black populations in the United States. While treatment advancements have greatly improved qualities of life for persons living with HIV/AIDS, prevention efforts remain focused to reduce incidence among vulnerable populations. Research distinguishing emerging adulthood in the US has characterized it entailing identity formations influencing sexual risk-taking. Religiosity and spirituality have remained pivotal in Black cultures influencing beliefs and normative behaviors around pre-marital sex. The Praying Hands study combines ethnic, demographic, contextual and socio-environmental factors to investigate influences of religiosity and spirituality on HIV risks among …

Characterization Of The Role Of Mitochondrial Function During Tumor Development And Muscle Wasting, Xiao Wang

Open Access Dissertations

Mitochondria play important roles in multiple cellular processes including energy metabolism, cell death, and aging. Regulated energy production and utilization is critical in maintaining energy homeostasis in normal cells and functional organisms. However, mitochondria go through a series of morphological and functional alterations during carcinogenesis. The metabolic profile in transformed cells is altered to accommodate their fast proliferation, confer resistance to cell death, or facilitate metastasis. On the organism level, mitochondrial function is crucial especially in tissues that require high energy supply, such as brain and skeletal muscle. Mitochondrial dysfunction has been implied in various neurodegenerative disorders and deteriorating chronic …

Freestanding And Support-Seeker Liana Seedlings: Spatial Distribution, Life History And Physiological Traits In Tropical Forests Of Central Panama., Eric J. Manzané Pinzón

Open Access Dissertations

Lianas is a term that identifies vines that produce secondary wood tissue and whose distribution is mostly restricted to the tropics. They usually start their lifecycle as seedlings in the forest understory an after a period of time they climb to the canopy forest supported by the surrounding vegetation. The seedling itself is an important stage on the plant’s life cycle; in this stage plants are susceptible to high mortality rates due to biotic or abiotic factors, such as predation, diseases, drought or flooding. Depending on the survival at this stage, they can extend their habitat range and colonize new …

Controlling Photochemical And Photophysical Behavior Of Organic Molecules Within A Water Soluble Host, Shampa R. Samanta

Open Access Dissertations

In this study we have investigated the possibility of controlling photochemical and photophysical behavior of small organic molecules by encapsulation within the cage of a deep-cavity cavitand, octa acid. Octa acid is soluble in basic aqueous medium and its interior cavity is benzene like which enable it to encapsulate small organic molecules forming host-guest complexes. The nature and stoichiometry of these complexes depend upon the size and hydrophobicity of the guest molecules. We have shown that the excited state dynamics of green fluorescent protein (GFP) chromophore derivatives can be controlled by encapsulation within octa acid. Octa acid can also selectively …

Development And Evaluation Of New Algorithms For The Retrieval Of Wind And Internal Wave Parameters From Shipborne Marine Radar Data, Björn Lund

Open Access Dissertations

The goal of this work is to develop and evaluate techniques for the retrieval of wind and internal wave (IW) information from marine X-band radar data. While ocean wind measurements are crucial for the transfer of energy and momentum across the air-sea interface, IWs play an important role in tidal energy transport. Marine radars work by transmitting microwave energy from a rotating antenna that also measures the backscatter. The radar backscatter from the sea surface is controlled by the wind-generated small ripple waves through the Bragg-scattering mechanism. Surface winds are thus the dominant factor for generating the radar backscatter. The …

Differential Regulation Of Autophagy By Therapeutic And Physiologic Glucose Restriction Under Normoxia And Hypoxia, Haibin Xi

Open Access Dissertations

Advances in our understanding of tumor biology achieved in the past decade have convincingly revealed the coupling of oncogenic transformation with increased glucose utilization, also known as aerobic glycolysis or the “Warburg effect”, that was observed more than 80 years ago. Although the altered glucose metabolism renders tumor cells selective growth and survival advantages, it also creates a therapeutic window to target cancer using extrinsic sugar analogs such as 2-deoxyglucose (2-DG). On the other hand, certain malignant cell populations inevitably face glucose starvation (GS) intrinsically arising as a solid tumor grows and the nutrient demand exceeds supply. In order to …

An Individual-Based Model To Evaluate The Effect Of Fisher Behavior On Reef Fish Catch Per Unit Effort, Steven E. Saul

Open Access Dissertations

Fisher’s decisions can influence the effectiveness of management measures as such decisions can allow fishers to dissipate the benefits of regulation. Furthermore, these decisions determine the spatial and temporal locations of fishery-dependent observations. In many stock assessments such observations are used to infer the abundance of fish populations and are essential in our efforts to understand the dynamics of fish stocks. In order to understand some of the ways that fisher behavior can influence our perception of abundance, an individual-based spatial model of the reef fish fishery off of the West Coast of Florida was developed. The spatial distribution of …

Physical Chemical Properties Of Trace And Minor Components Of Natural Waters: Solubility, Speciation, And Density, Ryan J. Woosley

Open Access Dissertations

The physical properties of minor/trace components of natural waters aren’t well known. Although these components have received a great deal of study recently only a small focus has been on properties such as speciation and solubility, which influence the behavior and fate in the environment. The pH has a large influence on speciation. This is of increasing importance due to ocean acidification from the anthropogenic input of CO2 into the environment and the resultant uptake by the oceans. Metals that form strong complexes with hydroxide and carbonate will see large changes speciation over the next few centuries. Metals with biological …

Osmoregulatory Physiology Of Pupfish (Cyprinodon Spp.) In Freshwater, Kevin V. Brix

Open Access Dissertations

Active uptake of Na+ at the gill by fish is fundamental to their osmoregulation and thus survival in freshwater environments. Studies to date have demonstrated several different mechanisms by which fish can accomplish this important physiological function. This dissertation provides a comparative characterization of Na+ uptake in the coastal pupfish, Cyprinodon variegatus variegatus (Cvv), the closely related Lake Eustis pupfish, C. v. hubbsi (Cvh), and the endangered desert pupfish, C. macularius (Cm). When acclimated to slightly saline freshwater (7 mM Na+) all three fish use a low affinity Na+/H+ exchanger (NHE) for apical Na+ uptake. Cvv also uses a Na+:K+:2Cl- …

Subantarctic Mode And Antarctic Intermediate Water During The Present And Last Glacial Maximum, Corinne A. Hartin

Open Access Dissertations

The formation of Subantarctic Mode Water (SAMW) and Antarctic Intermediate Water (AAIW) significantly contributes to the total uptake and storage of anthropogenic gases, such as CO2 and chlorofluorocarbons (CFCs), within the world's oceans. SAMW and AAIW formation rates in the South Pacific are quantified based on CFC-12 inventories using data from WOCE, CLIVAR, and data collected in the austral winter of 2005. This thesis documents the first wintertime observations of CFC-11 and CFC-12 saturations with respect to the 2005 atmosphere in the formation region of the southeast Pacific for SAMW and AAIW. CFC-12 inventories are 16.0x106 moles for SAMW and …

Regulation Of Cytochrome C Oxidase Composition By Oxygen And Oxidative Stress, Jingjing Liu

Open Access Dissertations

Cytochrome c Oxidase (COX) is a multimeric mitochondrial protein complex acting as the terminal enzyme of mitochondrial respiratory chain (MRC). It catalyzes the transfer of electrons from cytochrome c to molecular oxygen that is reduced to water. The efficiency of the electron transfer can be modulated in response to oxygen availability by differential expression and assembly into the holoenzyme of subunit isoforms-Cox5a/Cox5b. COX subunit 5 (Cox5) is the homologue of subunit 4 (COX4) in mammals. In both organisms it exists in two isoforms, whose expression is regulated by oxygen. In yeast grown in normoxia, most COX holoenzyme contains the isoform …