Digital Commons Network^™

Mechanistic Analysis Of Four-Way Dna Junctions And Cytokine-Binding Aptamers For Therapeutic Interventions, Roaa S. Mahmoud

Theses and Dissertations

DNA is inherently dynamic and topologically diverse and can fold into many different structures. Besides the canonical Watson-Crick structure, other higher-order structures such as G-quadruplexes (G4), i-motifs (iM), and four-way DNA junctions are possible. Although these high-order DNA structures are known to form transiently, they are important due to the crucial roles they play in many cellular processes including DNA replication, recombination, and repair. Among these DNA structures, 4-way junctions (also known as Holliday junctions, HJ) which are formed during the repair of double-strand DNA breaks (DSBs) and interact with proteins have garnered significant attention due to their central role …

Protacs – A Novel And Rapidly Developing Field Of Targeted Protein Degradation, Hannah R. Gatley

Theses and Dissertations

There is a continued need for new technology and strategies for tackling cancer and other diseases, and within the current century a novel therapeutic strategy has emerged in the realm of targeted protein degradation called Proteolysis-Targeting Chimeras (PROTACs). This technology specifically targets and degrades disease-causing proteins via the ubiquitin-proteasome system, and has seen an explosion of research and intrigue in both academia and industry over the past two decades. The diversity of PROTAC classes based on the E3 ligase recruiting ligand and the target protein allows for a universal molecular structure that can be customized for a specific target and …

Unraveling The Consequence Of Adult Onset Sulfatide Depletion: Its Implications In Myelin And Axonal Heath In The Context Of Neurodegenerative Disease, Elizabeth Dustin

Theses and Dissertations

Multiple Sclerosis is an immune mediated disease of the CNS. MS is diagnosed through detection of demyelinated regions. However, recent studies demonstrate that Normal Appearing White Matter (NAWM) contains substantial pathology. One such pathology observed in the NAWM is the reduction of sulfatide. The proper stoichiometry of lipids in myelin acts to maintain rapid conduction velocity, provide trophic support to the neuron, and protect the axon from degeneration. We previously characterized a mouse lacking sulfatide’s synthesizing enzyme, CST through constitutive gene disruption and demonstrate that sulfide is required for proper stability of the myelin sheath. However, since MS is typically …

Salinization Impacts On Heterotrophic Respiration, Ecosystem Respiration, And Plant Productivity In Tidal Freshwater Marshes, Kelsie J. Moses

Theses and Dissertations

Tidal freshwater marshes have preserved substantial stocks of soil carbon, which represents carbon dioxide that is no longer in the atmosphere. There is conflicting evidence in the literature about how disturbances such as sea level rise and associated wetland salinization impact the accumulation and long-term stability of this stored carbon. The goal of this experiment was to quantify how salinization impacts total ecosystem respiration and its component parts, autotrophic and heterotrophic respiration. This was a microcosm experiment using a C4 plant (Spartina cynosuroides) grown in soil derived from C3 plant matter and exposed to different salinities (0 to …

Stage-Structured Predator-Prey Interactions In A Warming World: A Case Study In Riverine Rock Pools, Andrew T. Davidson

Theses and Dissertations

Warming can impact predator-prey interactions through a variety of mechanisms. For example, warming can both alter the rate at which predators consume prey and the rate prey develop through vulnerable life stages. Thus, the overall effect of warming on consumer-resource interactions will depend upon the strength and asymmetry of warming effects on predator and prey performance. Here, we describe the consequences of these asymmetrical responses to temperature by first developing a simple stage-structured modeling framework, then applying that framework to predation of American rock pool mosquito larvae, Aedes atropalpus, by several common predators in riverine rock pools. We then …

Characterizing The Effects Of Antiandrogens And Senolytics To Enhance The Therapeutic Response To Castration-Resistant Prostate Cancer, Justin M. Silverman

Theses and Dissertations

Prostate cancer is the most frequently diagnosed cancer in males and the second most common cause of cancer deaths. Androgen deprivation therapy, whether through surgical or chemical castration, is the mainstay for treatment of advanced prostate cancer; however, despite an initial response, most patients eventually develop a progressive PSA rise, and castration- sensitive prostate cancer gives rise to castration-resistant prostate cancer. The standard of care therapy includes the antiandrogens such as enzalutamide and abiraterone acetate as well as the microtubule poison, docetaxel, and various immunotherapies; however, while prostate cancer research is progressing, there continues to be a compelling need for …

Kpt-330 Synergizes With Everolimus To Reduce Mtorc1-Overactive Basal-Like Triple-Negative Breast Cancer Brain Metastasis Burden, Aaron D. Valentine

Theses and Dissertations

Triple-negative breast cancer (TNBC), a highly metastatic breast cancer subtype, accounts for approximately 20% of all breast cancer diagnoses. Basal-like TNBC is notably difficult to treat due to the lack of actionable drug targets such as estrogen and progesterone receptors, as well as HER2. Due to the deficiency in TNBC-targeting drugs that are able to cross the blood-brain barrier (BBB) for breast-to-brain metastasis, there is a need to develop novel BBB-permeable treatments. After preliminary testing, KPT-330 (XPO1 inhibitor) and everolimus (FKBP1A/mTOR inhibitor) were selected as drug candidates for this study. Patient-derived xenograft (PDX) models for in vitro and in vivo …

Quantifying Insect Emergence In Tidal Freshwaters And The Importance Of Aquatic Prey In Wetland-Dependent Songbird Diet, Samantha L. Rogers

Theses and Dissertations

Insectivorous birds and their arthropod prey are experiencing widespread population declines, driven largely by anthropogenic disturbance and climate change. For wetland-dependent insectivores that consume a mixture of terrestrial and aquatic insects, understanding the availability, consumption, and nutritional qualities of aquatic diet subsidies is important for conservation. I use prothonotary warblers (Protonotaria citrea) as a model species throughout this work, because their breeding season aligns with aquatic insect emergence and they include aquatic insects when provisioning nestlings. In the first chapter, I estimate aquatic insect emergence from tidal freshwaters, which are understudied compared to nontidal systems. Using continuous field …

Climate, Physiology, And Distributions: The Role Of Thermal Physiology In Biological Invasions, Sean D. Powers

Theses and Dissertations

Climate is a primary factor influencing species range dynamics, particularly for ectotherms whose body temperature is closely tied to the surrounding conditions. While range shifts of ectotherms are attributed to climate warming, the mechanism driving these shifts are not well understood. Studies in macrophysiology demonstrate that the interaction of climate with thermal physiology plays a key role in determining large-scale spatial and temporal patterns for many temperature-sensitive physiological traits. This work has revealed a clear relationship between thermal tolerance breadth and range size. However, more recent analyses of this relationship demonstrate that thermal tolerance breadth only provides a partial explanation …

Genomic Comparison Of Dba/2j And C57bl/6j Strains Of Mus Musculus And Best Practice Of Genome Alignment For Bioinformatics Analyses, Dustin J. Zeliff

Theses and Dissertations

Alcohol use disorder is known to have significant genetic components that contribute to an individual’s susceptibility to the disease. Mouse models are commonly used to study the mechanisms underlying alcohol use disorder, with C57BL/6J (B6) and DBA/2J (D2) being two of the more prominently used inbred strains. Research in the Miles Laboratory has used these two strains, and genetic panels of mice derived from them, to identify potential genes associated with variance in ethanol-related behaviors using quantitative trait loci (QTL) analysis. For example, Ninein (Nin) was identified as a potential candidate gene for the anxiolytic effects of ethanol, discovered because …

A Standardized Pipeline For Isolation And Assembly Of Genomes From Symbiotic Bacteria In Whole Louse Genomic Sequence Data., Mohammad Mikail I. Bala

Theses and Dissertations

Many insects are known to harbour intracellular and heritable bacteria (endosymbionts), which provide their hosts with adaptive traits. Whole insect gDNA shotgun sequencing projects often sequence the genome of endosymbiont, in addition to the insect’s genome. There are approximately 600 whole genome shotgun libraries from insects available on the public repository (NCBI), which can be mined to obtain endosymbiont genomes. The assembly and annotation of endosymbiont genomes can contribute towards the exploration of their role as obligate symbiotic partners. However, de novo assembly of an endosymbiont genome, continues to be challenging, when the host and/or enteric bacterial gDNA is present …

Association Of Interpersonal Trauma And Polygenic Risk Scores With Depressive Symptoms In College Students, Rowan K. O'Hara

Theses and Dissertations

Major depression is considered a complex trait influenced by both polygenic risk factors and environmental exposures, such as childhood trauma. This study applied statistical genetic methods to calculate aggregate genetic risk for major depression to predict depressive symptoms scores in a college student sample. Data were from the Spit for Science (S4S) study in which college students from a large urban university self-reported interpersonal trauma (IPT) exposure prior to college and depressive symptoms from the past month (N = 7502; ancestry group: 20% African [AFR], 12% Admixed Americas [AMR], 10% East Asian [EAS], 49% European [EUR], 8% South Asian [SAS]). …

Treponema Denticola Synthesizes C-Di-Amp And Encodes The Cdaa-Type Diadenylate Cyclase Cdaa, Claire R. O'Brien

Theses and Dissertations

Periodontitis is a form of oral disease characterized by dysbiosis of the oral microbiome, leading to inflammation, bone resorption, and in severe cases, entire tooth loss, affecting 42% of adults in the US. One of the bacteria most associated with periodontal disease progression is Treponema denticola (Td), an oral spirochete which inhabits the mouth in small quantities during health but which can dominate the biofilms that form during periodontal disease. The ability of Td to survive in a disease environment and contribute to the progression of disease requires the use of robust signaling networks. Analysis of Td cultures …

Dune Building Dynamics Impact Cross-Island Connectivity And Barrier Island Characteristics, Alexander Sabo

Theses and Dissertations

Located at the land-sea interface, barrier islands are important protective features that reduce wave energy and erosion from mainland areas. Further, barrier islands provide habitat for many different organisms and serve as popular areas for recreation and tourism. As sandy landforms, barrier islands are easily disturbed, but often recover after disturbance as a result of island plant communities, specifically dune building grasses. Disturbance on barrier islands is driven by storms, tides, and overwash events. After disturbance has occurred, dune grasses colonize the dunes allowing for dune building and habitat restoration. On the Virginia barrier islands, there are three dominant dune …

The Type Iv Pilus Secretin Bfpb: Structural Analysis And Binding Interactions, Janay I. Little

Theses and Dissertations

Enteropathogenic Escherichia coli (EPEC) causes severe diarrhea in young children. The type IV pilus (T4P) of EPEC, known as the bundle-forming pilus (BFP), plays an important role in EPEC pathogenesis. T4Ps are a family of surface appendages that are important for adhesion, colonization, biofilm formation, virulence, twitching motility and many other functions. One essential component of the BFP system is the secretin, BfpB. Secretins are a large family of integral outer membrane proteins found in T4Ps as well as type II and type III secretion systems, and filamentous phages. Details of the secretin structure have been limited to the overall …

Patterns, Mechanisms, And Characterization Of Carbon Cycling Stability Following Partial Forest Disturbance, Kayla C. Mathes

Theses and Dissertations

Among the most essential questions in the era of climate change is how the forest carbon (C) cycle will respond to an increase in the extent of biotic disturbances from insects and pathogens. While research has focused on stand-replacing disturbance regimes, less is known about C cycling stability following partial disturbances that produce gradients of disturbance severity. Belowground C cycling responses to disturbance are especially poorly understood, even though temperate forest soils contain up to 50% of total ecosystem C and soil respiration (R_s) accounts for more than half of temperate forest C loss. Interpreting trends and mechanisms …

Evaluating How Acidic Solutions Affect The Microhardness Of Bioceramic Sealers, Colton Fischer

Theses and Dissertations

Introduction: With growing use of bioceramic sealers (BCS) in root canal therapy, there have been challenges when retreating BCS cases. Weak acids may be effective in removing BCS and their efficacy as a solvent can be measured by their influence on the microhardness of BCS. Microhardness can be used as an indirect measurement of material hardness. The purpose of this study was to investigate the microhardness of BCS when placed in contact with various acidic solutions to assess their potential use as a solvent for retreatment procedures.

Methods: EndoSequence BC Sealer (Brasseler USA) was injected into four 10 × 3mm …

Mechanistic Insight Into Traumatic Brain Injury Induced Neuronal Membrane Disruption: Cathepsin B Relocalization And A Neun Negative Cortical Neuron Subpopulation, Martina L. Hernandez

Theses and Dissertations

Traumatic brain injury (TBI) is a mechanical insult to the head that leads to brain damage and, in turn, causes long-term sensory, motor, cognitive, and affective dysfunction. Diffuse pathologies seen following such injury are associated with these life-altering outcomes that impact the daily lives of TBI survivors. The diffuse pathology that this body of work focuses on is neuronal membrane disruption; it is characterized by increased permeability of the neuron’s plasma membrane. Moreover, our lab had previously found that membrane disruption is exacerbated with intracranial pressure (ICP) elevation. We set out to measure the duration of membrane disruption following injury …

Tgif1 Physiological Levels Limit Β-Cell Distress And Neonatal Diabetes, Creighton J. Friend

Theses and Dissertations

TGIF1 belongs to the superfamily of homeodomain proteins, which regulate a wide variety of biological functions, including cell stemness and specification of cell fate during early development. Perhaps surprisingly, we found that enforced expression in pancreatic progenitor cells during embryogenesis resulted in severe diabetes, hinting at the possibility that TGIF1 might regulate pancreas development. Subsequent genetic experiments targeting β-cells showed that TGIF1 affected β-cell function and homeostasis. Transcriptomic analysis revealed that TGIF1 expression inhibits the expression of essential components of UPR signaling, underscoring a potential mechanism in which TGIF1 disrupts protein folding and secretion. Congruently, TGIF1 expression led to a …

Examining Genetically-Informed Etiologic Models Of Co-Occurring Posttraumatic Stress Disorder And Recreational Cannabis Use Among College Students, Terrell A. Hicks

Theses and Dissertations

The college years encompass a period of increased risk recreational cannabis use (RCU), as well as a time of increased risk for trauma exposure and developing posttraumatic stress disorder (PTSD). Given the high co-occurrence between RCU and PTSD, and the potentially negative consequences of the two (e.g., worse academic outcomes), there is a need to understand the etiologic mechanisms of these commonly co-occurring conditions. Two primary phenotypic models exist: self-medication model (i.e., PTSD to RCU) and the high-risk model (i.e., RCU to PTSD). To date, there are two existing studies longitudinally examining the etiologic models proposed to explain co-occurring RCU …

Novel Strategies In Head And Neck Tumor Therapy; Contribution Of Senescence In Therapy Response, And Resistance Development After Cisplatin Treatment, Fereshteh Ahmadinejad

Theses and Dissertations

Therapeutic outcomes achieved in head and neck squamous cell carcinoma (HNSCC) patients by concurrent cisplatin-based chemoradiotherapy initially reflect both tumor regression and tumor stasis. However, local, and distant metastasis and disease relapse as well as cisplatin-induced resistance are common in HNSCC patients. In the current work, we demonstrate that cisplatin treatment induces senescence in both p53 wild- type HN30 and p53 mutant HN12 head and neck cancer models. We also show that tumor cells can escape from senescence both in vitro and in vivo. We further established a cisplatin-resistant cell line from HN30 parental cell line that underwent brief senescence …

Plant Trait Effects On Tidal Wetland Methane Emission, Adam M. Dunn

Theses and Dissertations

High rates of carbon (C) sequestration exhibited by coastal wetlands is an important natural climate solution to global environmental change. At the same time, however, wetlands are the largest natural source of methane (CH₄) to Earth’s atmosphere, a potent greenhouse gas that influences the global climate. Wetland CH₄ emissions display high degrees of uncertainty in accounting for spatial and temporal variations in emissions due to the complex interactions between biotic and abiotic factors that influence methane production and transport, in addition to simultaneous influences from climate-driven effects on wetlands such as rapid sea level rise and increased …

Pre-Clinical Trials With Precision-Medicine Based Therapeutics In Basal-Like Patient-Derived Xenografts, David C. Boyd

Theses and Dissertations

Breast cancer treatments have improved over time, but the diseases seeing the most benefit from these improvements have the estrogen receptor, progesterone receptor, or are positive for HER2. Basal-like breast cancer tends to not have these biomarkers, which necessitates their treatment to be traditional, untargeted therapeutics which are less effective and tend to have harsh adverse effect profiles – this is an important unmet need. These studies utilize a variety of techniques, including tissue culture, viability assays, high-throughput screening, in vivo drug treatments and imaging, pathway analyses, molecular techniques such as Western blot, antibody arrays, RNA sequencing, sc RNA sequencing, …

Evaluation Of Spliceai For Improved Genetic Variant Classification In Inherited Ophthalmic Disease Genes, Melissa Reeves

Theses and Dissertations

ABSTRACT

EVALUATION OF SPLICEAI FOR IMPROVED GENETIC VARIANT CLASSIFICATION IN INHERITED OPHTHALMIC DISEASE GENES

By Melissa Jean Reeves, Ph.D.

A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Virginia Commonwealth University.

Virginia Commonwealth University, 2023

Major Director: Melissa Jamerson, PhD, MLS(ASCP)

Associate Professor, Department of Medical Laboratory Sciences

Inherited ophthalmic diseases impact individuals around the globe. Inherited retinal diseases (IRDs) are the leading cause of blindness in individuals aged 15 to 45. The personal, social, and economic impact of vision loss is profound. Due to individual differences, symptoms can be variable, and …

The Role Of Human Dopamine Transporter Threonine 261 And Serine 262 In Amphetamine Regulation Of Transporter Function And Surface Expression, Sina Abdollahi

Theses and Dissertations

Amphetamine (AMPH) has been used clinically and recreationally around the world for years. A 2021 study reports a 67.5% rise in AMPH use from 2010-2017 across all fifty states. Study also shows that 30% of patients with AMPH-induced psychosis end up with primary psychosis over time. AMPH works by inhibiting monoamine (Norepinephrine (NE), Serotonin (5-HT), and Dopamine (DA) reuptake followed by triggering transporter mediated monoamine release and consequently increases monoamine concentrations in extracellular synaptic space. AMPH also works as a substrate for monoamine transporters, enters the neuron, and once its inside the neuron, it will prevent the storage of monoamines …

Bioinformatic Pipeline For Determining Terminal Repeats In The Human Cytomegalovirus Genome Assembled With Pacbio Long Read Sequences, Ahmed Al Qaffas

Theses and Dissertations

Human Cytomegalovirus (HCMV) is a member of the betaherpesvirinae subfamily of the Herpesvirus family. HCMV infection is common among adults worldwide, with an estimated seroprevalence of 66 to 95%, depending on the geographic region (Zuhair et al., 2019). Although most of the virus genomic content has been studied extensively, the terminal repeating region sequences remain understudied. Two main challenges hindered the study of the region: a) limitations of sequencing technologies; and b) misassembly of the repeats due to its complex nature. Here I show a novel bioinformatics pipeline that takes advantage of PacBio's long reads to resolve the challenges mentioned …

Biotic Characteristics Of Managed And Unmanaged Coastal Dunes In The Outer Banks, North Carolina, Andrew E. White

Theses and Dissertations

Under future climate change and sea level rise scenarios, Natural and Nature-Based Features (e.g., dunes) that protect coastal habitat and infrastructure will be exposed to increased wave energy and storm surge. Understanding how these forces will impact coastal dunes is necessary for their continued use as protective features. Coastal dunes develop through feedback between vegetation and sediment deposition, a process complicated by species-specific growth rates and responses to burial. Wave flume studies have tested the effects of dune vegetation on erosion and found multiple plant organs across several functional types to be important for resisting erosion. Although dune building and …

Estimating Weighted Panel Sizes For Primary Care Providers: An Assessment Of Clustering And Novel Methods Of Panel Size Estimation On Electronic Medical Records, Martin A. Lavallee

Theses and Dissertations

Primary Care is on the frontlines of healthcare, thus they see the most diverse set of patients. In order to achieve high functioning primary care, a practice must establish empanelment, the pairing of patients to providers. Enumeration of empanelment, or estimating panel sizes, helps ensure that the demands of the patients demand the supply of providers and optimize the balance of primary care resources to improve quality of care. Further we can adjust panel sizes by using patient-level data on healthcare utilization and complexity extracted from the electronic medial record to determine the amount of care or burden of work …

The Role Of Irf-1 In Spontaneous Mouse Glioma, Aakash B. Vaidya

Theses and Dissertations

Glioblastoma Multiforme has been shown to be one of the deadliest primary brain cancers. One of the reasons why GBM is so deadly, is a unique immunosuppressive tumor microenvironment that promotes GBM growth and progression. Both astrocyte and microglia have been implicated in immunosuppression. In this study, we explored the role of Interferon Regulatory Factor 1 (IRF-1) in astrocytes and glioma cells on the growth of spontaneous glioma tumors. IRF-1 is regulated by the JAK/STAT pathway and induces expression of Programmed death ligand 1 (PD-L1). PD-L1 downregulates immune responses to glioma. We found that IRF-1 had no effect on spontaneous …

The Influence Of Salinity On The Structure And Function Of Soil Prokaryotic Communities In Coastal Freshwater Wetlands, Joseph C. Morina Ii

Theses and Dissertations

Microbial communities are critical biological components of the world’s ecosystems, and their respiratory pathways are directly involved in the biogeochemical cycling of essential nutrients. As genomic technologies advance, allowing for more detailed profiling of microbial communities, efforts have successfully linked microbial community composition to ecosystem-level functions and have shown microbial communities are susceptible and resistant to disturbance events. The goal of this dissertation is to address the temporal scales in which microbial communities respond to the disturbance of salinization, and the repercussions this has on microbially-meditated carbon and nitrogen cycling. Coastal freshwater wetlands are an excellent study system to investigate …