Digital Commons Network^™

Identifying And Targeting Cancer Stem Cells In Colorectal Cancer, Amber Harnett

Electronic Thesis and Dissertation Repository

The cancer stem cell hypothesis posits that cancer stem cells (CSCs) are the driving force behind tumour progression and metastasis, making them ideal therapeutic targets. Previous research identified Leucine-rich repeat-containing G-protein-coupled receptor 5 (Lgr5) as a marker of CSCs in colorectal cancer (CRC). However, it is not known whether more than one CSC population exists in CRC. Identifying and targeting CSCs in CRC is important for effective treatment of cancer patients. Here, I show that Keratin-19 (K19) labels intestinal CSCs in mouse tumours that recapitulate the early stages of CRC. Moreover, selective ablation of Lgr5 has no effect on tumour …

Effect Of Bacterial Superantigens On The Magnitude And Breadth Of Influenza-Specific Cd8+ T Cell Responses, Courtney Meilleur

Electronic Thesis and Dissertation Repository

Severe cases of influenza A virus (IAV) infection are often complicated by concomitant bacterial pneumonia or sepsis. Many bacterial species are capable of producing potent immunomodulators called superantigens (SAgs), which have the potential to interfere with cell-based antiviral immune mechanisms. I asked what effects bacterial SAgs have on both the magnitude and the breadth of antiviral CD8⁺ T cell (TCD8⁺) responses. Surprisingly, administration of SAgs to mice shortly before or after vaccination with IAV increased the number of primary TCD8⁺ responding to select IAV-derived epitopes. T cell receptor staining of these SAg-augmented populations revealed expression of …

The Role Of Tbx3 In Early Breast Cancer Progression, Milica Krstic

Electronic Thesis and Dissertation Repository

TBX3 is a transcriptional regulator involved in embryonic development and in tumorigenesis of several cancer types. There are two isoforms of TBX3 (TBX3iso1 and TBX3iso2) with different DNA binding domains. The large-scale functional roles of TBX3iso1 and TBX3iso2 were characterized in a breast cancer context. Both TBX3 isoforms induced invasiveness and an epithelial-to-mesenchymal (EMT) phenotype. Coupling data from genome-wide ChIP-array and RNA-Seq studies provided a novel list of genes regulated by each isoform. Both TBX3 isoforms regulate expression of several EMT-related genes, including SLUG and TWIST1. Importantly, TBX3 is a direct regulator of SLUG, and SLUG expression is required for …

Evaluating The Conservation Of Rna Packaging Enhancer Elements Across Lentiviruses, Seyed Arad Moghadasi

Electronic Thesis and Dissertation Repository

It was previously thought that the RNA structural elements within the 5’UTR were the sole determinants of RNA packaging in HIV-1. However, in 2013 Chamanian et al. discovered that the region overlapping the Ribosomal Frameshift Signal (RFS) acted to enhance RNA packaging 50 fold and was thus named the genomic RNA packaging enhancer element (GRPE). To determine if the GRPE was conserved across lentiviruses, using the same approach as Chamanian et al., deletions in similar regions of the SIVmac239 and FIV 34TF10 genomes were done to measure their impact on RNA packaging. No region across the gag-pol ORF of SIVmac239 …

The Use Of Current Steering During Subthalamic Deep Brain Stimulation To Alleviate Upper Limb Symptoms Of Parkinson's Disease, Shabna Iftikar Mohideen

Electronic Thesis and Dissertation Repository

Subthalamic (STN) deep brain stimulation (DBS) is an established treatment to alleviate the appendicular motor symptoms of Parkinson's Disease (PD). Current steering during DBS allows the unequal fractionation of current between two electrodes on the lead, resulting in a non-spherical electrical field. It is hypothesized that the way the electrical field is shaped will affect a patient’s upper limb symptom alleviation. Seven PD patients who underwent bilateral STN-DBS were tested over four weeks post-operation. 16 current fractionation settings were tested each week at an amplitude that increased weekly. Optimal setting was defined as the setting that provided the best …

The Effect Of Function-Blocking Rhamm Peptides In A Mouse Model Of Bleomycin-Induced Systemic Sclerosis, Kitty Y. Wu

Electronic Thesis and Dissertation Repository

Systemic sclerosis is a chronic, fibrotic disorder associated with high disease-specific mortality and morbidity. Cutaneous manifestations include dermal thickening and obliteration of dermal adipose tissue. The efficacy of function-blocking Rhamm peptides, NPI-110 and NPI-106, were tested in reducing skin fibrosis and promoting adipogenesis in a bleomycin-induced mouse model of systemic sclerosis. NPI-110 reduced both visible measures of fibrosis (dermal thickness, collagen density, and fibril bundling) and mRNA expression of pro-fibrotic genes (Tgfb1, c-Myc, Col1a1, Col3a1). While there was no measurable change in dermal adipose thickness, NPI-110 treatment upregulated Perilipin mRNA and Adiponectin protein expression and is therefore hypothesized to …

White Matter Inflammation And Executive Dysfunction: Implications For Alzheimer Disease And Vascular Cognitive Impairment, Alexander Levit

Electronic Thesis and Dissertation Repository

White matter integrity is crucial to healthy executive function, the cognitive domain that enables functional independence. However, in the ageing brain, white matter is highly vulnerable. White matter inflammation increases with age and Alzheimer disease (AD), which disrupts the normal function of white matter. This may contribute to executive dysfunction, but the relationship between white matter inflammation and executive function has not been directly evaluated in ageing nor AD. White matter is also particularly vulnerable to cerebrovascular disease, corresponding with the common presentation of executive dysfunction in vascular cognitive impairment (VCI). Thus, white matter may be an important substrate by …

Effects Of Maternal Protein Restriction On The Pulmonary Surfactant System During The Early Life And Adulthood, Reza Khazaee

Electronic Thesis and Dissertation Repository

Fetal growth restriction (FGR) is defined by low birth weight and contributes to a variety of adult-onset diseases with different severities between males and females. However, the effects of FGR on the pulmonary surfactant are not fully elucidated. In this thesis, first, we investigated the FGR effects on the lung function and the surfactant system at the early postnatal life. It was hypothesized that FGR contributes to alterations of lung mechanics and the surfactant system during the neonatal period. Second, we assessed the FGR effects on the surfactant system in response to sepsis in adulthood. It was hypothesized that FGR …

Limbic System Involvement In Absence Seizures, Rukham Ajaz

Electronic Thesis and Dissertation Repository

Absence epilepsy is characterized by brief spells of absent stare and spike wave discharges (SWDs), generally believed to be generated by a thalamocortical network. Our lab showed that hippocampal neuronal firings were synchronous with SWDs in a gamma butyrolactone (GBL) model of absence epilepsy in rats (Arcaro et al., 2016). We hypothesize that, in a GBL model of absence seizures, 30-400 Hz oscillations in the spontaneous local field potentials (LFPs) in the hippocampus and other parts of limbic system (amygdala and nucleus accumbens) are phase modulated by SWDs, and this modulation is mediated through nucleus reuniens of midline thalamus (RE). …

Lung-Derived Selectins Interact With Cd44 And Enhance The Migration Of Breast Cancer Cells, Sami U. Khan

Electronic Thesis and Dissertation Repository

The lung is among the deadliest sites of breast cancer metastasis. Previous work from our laboratory demonstrated that aggressive CD44-expressing breast cancer cells preferentially metastasize to the lung in vivo, and observed the presence of multiple CD44-interacting proteins in the lung including E-, L- and P-selectin. We hypothesized that lung-derived selectins promote breast cancer migration and/or growth via interactions with CD44. Using an ex vivo model of the soluble lung-microenvironment, we demonstrate that lung-derived selectins enhance in vitro migration but not proliferation of breast cancer cells. Co-immunoprecipitation experiments reveal that CD44 expressed by breast cancer cells in vitro interacts …

The Brain-Heart Connection: Establishment Of A Novel Rodent Model Of Focal Insular Ischemic Stroke To Examine The Pathophysiology Of Stroke-Induced Heart Injury, Victoria Thorburn

Electronic Thesis and Dissertation Repository

The neurological influence of ischemic stroke in the generation of stroke-induced heart injury (SIHI) has been acknowledged for several years. However, pathophysiological mechanisms remain uncertain. Clinically, it is hypothesized that stroke involving the insular cortex (IC) initiates SIHI, since the IC controls autonomic regulation of cardiovascular function. Yet, given the high prevalence of shared risk factors between ischemic stroke and cardiovascular disorders, mechanistic conclusions from clinical studies are largely speculative. We therefore sought to establish a novel rodent model of focal insular ischemic stroke, used to evaluate chronic outcomes of SIHI. Focal ischemic stroke was induced into the right or …

The Role Of Cholinergic Signaling In Cardiac Function, Rachel Reingold

Electronic Thesis and Dissertation Repository

Cardiovascular disease is one of the leading causes of death in Canada. Treatment currently focuses on preventing the increase of sympathetic signaling seen in heart failure. However, it has recently been noted that cardiac function is dependent on parasympathetic tone. Previous studies have demonstrated the development of heart failure when cholinergic targets are knocked out in cardiomyocytes. Transgenic mouse models that have increased cholinergic transmission show protection against cardiovascular insults. We have shown that transgenic mice overexpressing vesicular acetylcholine transporter in cholinergic cells show cardiovascular protection in response to ex vivo insults. As well, this protection is seen when cholinergic …

The Effects Of Tracheal Occlusion On Wnt Signaling In A Rabbit Model Of Congenital Diaphragmatic Hernia, Martina M. Mudri

Electronic Thesis and Dissertation Repository

Purpose: Tracheal occlusion (TO) reverses pulmonary hypoplasia (PH) in congenital diaphragmatic hernia (CDH), but its effect on epithelial-mesenchymal transition (EMT) in lung development remains poorly understood. The purpose of this study was to a) confirm the CDH rabbit model produced PH which was reversed by TO and b) determine the effects of CDH +/- TO on EMT pathways.

Methods: CDH was created at 23 days, TO at 28 days and lung collection at 31 days gestation in fetal rabbits. Lung body weight ratio (LBWR), mean terminal bronchiole density (MTBD), and expression of mRNA and micro-RNA was determined.

Results: Fifteen CDH, …

Understanding The Impact Of Hiv-1 Genetic Diversity On The Function Of Nef And Its Role In Serinc5 Antagonism, Aaron Leslie Johnson

Electronic Thesis and Dissertation Repository

HIV-1 Nef is a key pathogenic protein, allowing HIV-1 to evade the host immune system by downregulating MHC-I and CD4. Furthermore, it was recently discovered that Nef counteracts the host factor SERINC5 to increase HIV-1 infectivity, but the mechanistic details of the Nef:SERINC5 interaction still need to be explored. Throughout this dissertation, I will explore the hypothesis that the genetic diversity that defines HIV-1 has a pronounced effect on the HIV-1 protein Nef, altering its function between and within group M subtypes. To address this hypothesis I investigated how MHC-I and CD4 downregulation differ among all non-recombinant group M subtypes. …

The Epidemiology Of Infective Endocarditis Among People Who Inject Drugs In London, Ontario., Brian Hallam

Electronic Thesis and Dissertation Repository

Infective endocarditis is an infectious disease that affects the valves of the heart. Injection drug use is currently a leading risk factor among patients with endocarditis. We conducted a prospective study using data from hospital chart records among patients with endocarditis in London, Ontario, which has a relatively high prevalence of people who inject drugs to assess the severity of the issue and the major risk factors of mortality pertaining to this population. This study had a sample size of 353 and included a review of the incidence of admissions of endocarditis, as well as a survival analysis, using both …

Tomographic And Histological Analyses Of Ectopic Calcification Associated With Diffuse Idiopathic Skeletal Hyperostosis (Dish), Dale Edward Fournier

Electronic Thesis and Dissertation Repository

Diffuse idiopathic skeletal hyperostosis (DISH) is a non-inflammatory spondyloarthropathy characterised by the formation of ectopic calcifications of the ligaments/enthuses along the anterolateral aspect of the vertebral column. Despite affecting 15-25% of North Americans over the age of 50, the aetiology of DISH is poorly understood and there are no disease modifying treatments. Our discovery-based approach implemented a transdisciplinary research team to study the basic biology, imaging science, clinical anatomy and significance of DISH in humans. Our novel characterisation defined distinct morphological presentations of ectopic calcifications associated with DISH in cadaveric specimens using micro-computed tomography imaging. Subsequent histopathological analyses demonstrated that …

Elucidating The Importance Of Hope And Its Potential Lewis Glycosylation In Helicobacter Pylori, Keertika Yogendirarajah

Electronic Thesis and Dissertation Repository

Helicobacter pylori colonizes 50% of the world’s population, whereby glycoproteins and Lewis Y-containing lipopolysaccharides contribute to its pathogenesis. We investigated whether the HopE porin is glycosylated, if the glycan is Lewis Y, and if this is mediated by the putative oligosaccharide transferase HP0946 or the O-antigen ligase WaaL. Western blotting was performed on outer membranes with anti-HopE antibodies, anti-Lewis Y antibodies and fucose-binding BambL lectin to ascertain HopE glycosylation. We discovered that HopE is likely glycosylated by a non-Lewis Y fucose-containing glycan and neither HP0946 nor WaaL are the transferase. Additionally, we investigated HopE’s role in antibiotic susceptibility via Etest …

Impact Of Feeding Tube Status On Health Outcomes For Individuals With Oropharyngeal Cancer, Nedeljko Jovanovic

Electronic Thesis and Dissertation Repository

Abstract

This study investigated differences in outcomes related to health, swallowing, and quality of life (QoL) for individuals with oropharyngeal squamous cell carcinoma (OPSCC) receiving either radiotherapy (RT) alone, or concomitant chemoradiotherapy (CRT). Differences were assessed based on whether patients received a feeding tube (FT group) or not (NFT group). Measures including the Functional Oral Intake Scale (FOIS), Performance Status Scale for Head and Neck Cancer (PSS-HN), M.D. Anderson Dysphagia Inventory (MDADI), and weight were collected for 126 individuals at baseline, and at 3, 6, and 12 months post-treatment. Data were analyzed to identify potential prognostic differences between the groups, …

Measurement And Protection Of Lung Health In Poultry Farmers Of Southwestern Ontario, Rose-Marie Doyon Dolinar

Electronic Thesis and Dissertation Repository

Chronic obstructive lung disease (COPD), develops gradually, and tends to be noticed by farmers only after there has been a significant loss of lung function. People with symptoms of COPD often present for health care in later stages of disease, because they accept cough or breathlessness as “normal”.

Measurement of lung health for those at risk of developing COPD provides an opportunity for early detection of lung disease, and deter the progression toward irreversible damage to the lungs. COPD is, however, under-diagnosed.

The importance of bringing primary care providers and farmers together, and acknowledging the high-risk nature of occupational exposures, …

Drug Response And Metabolism In Crohn's Disease, Aze Wilson

Electronic Thesis and Dissertation Repository

Inflammatory bowel disease (IBD) is an illness of chronic intestinal inflammation comprised of Crohn's disease (CD) and ulcerative colitis (UC). Specialists rely heavily on drugs that target a dysregulated immune system. There is a staggering degree of variation in drug response in CD. Our understanding of drug metabolism and response in IBD is limited. Gaining new insights into IBD-specific modifications of drug metabolism may allow for improved drug efficacy and reduced toxicity. Cytochrome P450 (CYP) 3A4 is the most relevant determinant of drug metabolism and exposure for medications prescribed today. CYP3A4 is highly expressed in the liver, but is also …

Attenuation Of Obesity, Hepatic Steatosis And Reversal Of Atherosclerosis By The Flavonoids Naringenin And Nobiletin, Amy C. Burke

Electronic Thesis and Dissertation Repository

Naringenin and nobiletin are naturally-derived citrus flavonoids that have significant lipid-lowering and insulin sensitizing effects in vitro and in vivo. In murine models of obesity, metabolic dysfunction and atherogenesis, these flavonoids protect against the development of cardiometabolic disease. However, the ability of naringenin and nobiletin to reverse existing metabolic dysfunction and atherosclerosis has not been investigated.

The purpose of this thesis was to investigate the ability of the citrus flavonoids, naringenin and nobiletin, to reverse obesity, metabolic syndrome and atherosclerosis in two different mouse models of atherosclerosis regression. The first chapter demonstrates in Ldlr^-/- mice with diet-induced obesity, …

Effects Of G Protein Signalling Modulator 3 On Cellular Signalling, Aneta A. Surmanski

Electronic Thesis and Dissertation Repository

G protein coupled receptors (GPCRs) promote G protein heterotrimer (Gα·GDP/Gbg) activation.GPCRsignalling is limited via G protein GTPase activity and b-arrestin-receptor interactions. G Protein Signalling Modulators (GPSMs) are proteins that may influence receptor signalling through G protein activity. GPSM3 modulates their activity by binding to Ga_i-GDP, limiting nucleotide exchange and preventing its re-association to Gbg. The impact of GPSM3 on signalling is unknown.We hypothesize that GPSM3 will decrease Ga_i-dependent signalling while promoting Gbg-dependent signalling in G_i-coupled GPCRs.

GPSM3 significantly inhibited b-arrestin recruitment to α_2A-adrenergic and m-opioid receptors via a Gbg-dependent mechanism, …

Role Of Long Noncoding Rnas In Diabetic Complications, Anu Alice Thomas

Electronic Thesis and Dissertation Repository

LncRNAs, recently found to be pervasively transcribed in the genome, can play key roles in epigenetic modifications during gene transcription. Their role in diabetic complications are however not clear.

Using array analysis, we identified alterations of two lncRNAs in high glucose (25mM/L,HG) treated retinal endothelial cells (HRECs). ANRIL expressions were further measured with or without siRNA knockdown in ECs. ANRIL knockout (KO) mice with or without streptozotocin (STZ)-induced diabetes were also investigated for mRNA and protein expression of VEGF and ECM proteins FN and Col1α4. ANRIL knockdown prevented glucose-induced increased VEGF, FN and Col1α4 levels. Comparable results were observed in …

The Development Of A Temporomandibular Force Simulator To Study Craniofacial Strain In-Vitro, Kenneth Kc Ip

Electronic Thesis and Dissertation Repository

An in-vitro musculoskeletal loading simulator was developed to replicate the internal forces of mastication, and then employed in a comparison of clinically relevant facial fracture repairs. Muscle forces are simulated by pneumatic pistons via 3D printed mounts that are reverse-engineered from CT scan to match muscle attachment sites, which are adhered to bone in order to simulate native stress distributions. Bite force and bone strain pattern of the craniofacial structure under load were measured using a force sensor and strain gauges respectively. In a series of five fresh-frozen cadaveric heads, it was found that strain patterns of the craniofacial structure …

Evaluating White Matter Changes And Executive Function In Rat Models Of Mediodorsal Thalamic Stroke And Neuroinflammation, Jessica Garabon

Electronic Thesis and Dissertation Repository

Recent literature has supported a relationship between vascular disease and its role in the progression of cognitive impairment. Previous studies have demonstrated that white matter inflammation (WMI) in the brain is a common pathological outcome following stroke. Moreover, WMI has been shown to be the strongest predictor of cognitive decline following stroke. Finally, previous work in our lab has demonstrated, using a rodent model of striatal stroke, that WMI is correlated with post-stroke cognitive impairment. The current study aimed to further investigate the role of WMI in post-stroke cognitive impairment by utilizing a mediodorsal thalamic (MD) stroke model in the …

Investigating The Pathogenesis Of Staphylococcus Aureus In Periprosthetic Joint Infections, Santiago L. Iglesias

Electronic Thesis and Dissertation Repository

The most challenging complication after total joint replacement is the periprosthetic joint infection (PJI). Staphylococcus aureus is a commensal bacterium and a human pathogen. It is responsible for more than half of the PJI. We demonstrated that synovial fluid has antimicrobial properties against S. aureus and the iron restriction is one of the mechanisms used for the host to prevent bacterial growth, and is even able to increase killing of S. aureus. We have shown a clear role of transferrin as a restrictive factor in synovial fluid that functions by iron starving the bacteria and sensitizing them to killing …

Characterization Of Human Prostate Cancer Using Sodium Magnetic Resonance Imaging, Nolan Christopher Broeke

Electronic Thesis and Dissertation Repository

Overtreatment of prostate cancer is a significant problem in the health care of men. Development of non-invasive imaging tools for improved characterization of prostate lesions has the potential to reduce overtreatment. In this thesis work, we will evaluate the ability of tissue sodium concentration obtained from sodium magnetic resonance imaging (sodium-MRI) to characterize in vivo prostate lesions. Imaging data, including multi-parametric magnetic resonance imaging (mpMRI) and sodium-MRI, were obtained from a cohort of men with biopsy-proven prostate cancer and compared to digitized whole-mount histopathology after prostatectomy. Histopathology was independently graded for Gleason score to be used as the ground truth …

Role Of The Dorsal Striatum In Learning And Decision Making, Nole M. Hiebert

Electronic Thesis and Dissertation Repository

The striatum, the input region of the basal ganglia, has been shown to mediate many cognitive functions. The striatum itself can be functionally segregated into dorsal (DS) and ventral striatum (VS). For more than 60 years, DS has been reported to mediate stimulus-response learning, though evidence has been accruing pointing to a role in decision making. These literatures have been growing independently and an aim of this thesis was to bridge these two bodies of knowledge. We directly investigated the role of DS in stimulus-response learning versus decision making using functional magnetic resonance imaging (fMRI) in patients with Parkinson’s disease …

Increased Mitochondrial Calpain-1 Is An Important Mechanism Contributing To Mitochondrial Ros Generation In Cardiac Diseases, Rui Ni

Electronic Thesis and Dissertation Repository

Both calpain activation and excessive mitochondrial reactive oxygen species (mtROS) have been implicated in the pathogenesis of cardiac diseases. We investigated whether and how calpain regulates mtROS generation in mediating cardiac diseases.

In mouse models of streptozotocin-induced type-1 diabetes and lipopolysaccharides- induced sepsis, we show that the protein levels of calpain-1 and calpain activities in mitochondria were significantly elevated in diabetic and septic hearts. The elevation of mitochondrial calpain-1 correlated with an increase in mtROS generation and oxidative damage. Importantly, cardiomyocyte-specific deletion of capns1 disrupted calpain-1 and calpain-2 in the heart and prevented mtROS generation in both septic and diabetic …

Computational Modelling Of Human Transcriptional Regulation By An Information Theory-Based Approach, Ruipeng Lu

Electronic Thesis and Dissertation Repository

ChIP-seq experiments can identify the genome-wide binding site motifs of a transcription factor (TF) and determine its sequence specificity. Multiple algorithms were developed to derive TF binding site (TFBS) motifs from ChIP-seq data, including the entropy minimization-based Bipad that can derive both contiguous and bipartite motifs. Prior studies applying these algorithms to ChIP-seq data only analyzed a small number of top peaks with the highest signal strengths, biasing their resultant position weight matrices (PWMs) towards consensus-like, strong binding sites; nor did they derive bipartite motifs, disabling the accurate modelling of binding behavior of dimeric TFs.

This thesis presents a novel …