Medicine and Health Sciences Commons^™

Transferring Organelles Into Native Neurons: A Disease-Modifying Therapy For Neurodegenerative Disorders, Lohiny Balendran

Electronic Thesis and Dissertation Repository

Currently, there are no disease-modifying therapies to counter the progression of neurodegenerative diseases that are associated with mitochondrial dysfunction in the early stages. In this study, we have used a novel strategy of cell fusion to transfer mitochondria from one cell to another using fusogens (syncytin 1 and syncytin 2). Syncytins are placental proteins encoded by endogenous retroviral envelope genes that promote cellular fusion. In this study, we have proposed that donor cells engineered to stably express syncytin when cocultured with recipient cells will allow fusion and facilitate the transfer of mitochondria into recipient cells. Syncytin-mediated systems revealed about 16.6-18.5% …

Characterizing The Function Of B Cells That Accumulate In The Inflamed Central Nervous System In Anti-Myelin Autoimmunity, Lika Chowdhury

Electronic Thesis and Dissertation Repository

While the role of autoimmune T cells has been extensively studied in anti-myelin

autoimmunity, little is known about the function of B cells in multiple sclerosis (MS), a chronic inflammatory disease of the central nervous system (CNS). B cells form clusters with T cells in the meninges directly adjacent to demyelinating lesions. Previous studies have shown that disease progression is dependent on the depletion of specific populations of B cells, but it is not clear which contributes to pathology or how. The purpose of this thesis is to characterize the population of meningeal B cells to determine how they differ …

A Theoretical Perspective On Parasite-Host Coevolution With Alternative Modes Of Infection, George N. Shillcock

Electronic Thesis and Dissertation Repository

We investigate how natural selection shapes the coevolution of parasitism. We discuss the antagonism fuelled by parasites’ necessity to transmit to novel hosts, and host’s desire to minimise virulence. In support, we build a mathematical model which considers the epidemiology and life-history trade-offs faced by an obligate microparasite and its host. Our model allows parasites to be transmitted to new hosts via direct contact (horizontally) or from parent to offspring during birth (vertically). We test the hypothesis that vertical transmission causes virulence to diminish in the long run, and contrary to widely accepted views, find that vertical transmission need not …

Trna Regulation In Humans: The Cellular Effect Of A Pathological Hars Y454s Mutation, Rosan Kenana

Electronic Thesis and Dissertation Repository

tRNAs are the adapter molecules involved in translating the genetic code into functional protein in a living cell. tRNAs are charged with their cognate amino acids - by aminoacyl-tRNA synthetases (aaRS or ARS) - which are then transferred to a growing peptide in a process called mRNA translation. The efficiency of translation is dependent on the ratio of ARS enzymes to their cognate tRNAs and the availability of correctly amino acylated tRNAs. Disruptions of this process, caused by mutations in ARS genes, in particular, have been linked to complex inherited diseases. USH3B syndrome, a recessively inherited disorder among consanguineous families …

Multi-Scale Evolution Of Virulence Of Hiv-1, David W. Dick

Electronic Thesis and Dissertation Repository

HIV-1 is a rapidly replicating retrovirus that faces two distinct fitness landscapes: within-host HIV-1 faces viral competition for host cells and for escape from the immune system, and between hosts HIV-1 faces a transmission bottleneck in which the majority of new infections are started by a single virus strain. Possibly as a result of these conflicting selective pressures, the rate of evolution of HIV-1 tends to be greater within-host than between hosts.

A current hypothesis for this difference in evolutionary rates is that the HIV-1 latent reservoir acts to archive virus for later transmission. We offer a related but complimentary …

Behavioural And Molecular Consequences Of Postnatal Stress In A Mouse Model Of Fetal Alcohol Spectrum Disorder, Bonnie Alberry

Electronic Thesis and Dissertation Repository

Fetal alcohol spectrum disorders (FASD) are caused by prenatal alcohol exposure (PAE) and affect 1‑5% of the North American population. Children born with FASD often face maternal separation throughout childhood. How this early life stress (ELS) affects the severity of FASD-related deficits is poorly understood. Using a mouse model, this dissertation establishes that behavioural deficits accumulate following prenatal alcohol exposure and early life stress, assessed using tests for activity, anxiety-like behaviour as well as learning and memory. Hippocampal gene expression was evaluated using RNA-seq followed by clustering of expression profiles through weighted gene co-expression network analysis (WGCNA). A set of …

Discovery Of Novel Mechanisms Regulating Cancer Extravasation In The Chorioallantoic Membrane Model, Yohan Kim

Electronic Thesis and Dissertation Repository

Cancer metastasis is a multistep process that begins with the invasion of tumour cells into the stroma and migration towards the blood vessels. Tumour cells that have entered the bloodstream must then survive and leave by a process known as extravasation. Finally, extravasated cells proliferate and establish the secondary site in the metastatic cascade. Although extravasation encompasses key events during cancer cell invasion to aid in the development of effective treatments, an in vivo model that rapidly, reproducibly and economically recapitulates cancer cell extravasation is needed. Therefore, the objectives of my research were to 1) establish and validate an in …

The Role Of Kidney Injury Molecule-1 In The Metastasis Of Renal Cell Carcinoma, Jasper Lee

Electronic Thesis and Dissertation Repository

Over 30% of patients with renal cell carcinoma (RCC) present with metastases, with median survival of 2 years. Kidney injury molecule 1 (KIM-1) is a cell-surface glycoprotein expressed by >90% of RCC tumours. Preliminary data mined from The Cancer Genome Atlas RNA-sequencing database indicates that KIM-1 overexpression predicts overall survival in patients. Here we sought to determine if tumour KIM-1 plays a role in RCC cell extravasation and metastasis to the lungs. In vitro invasion and in vivo metastasis assays were performed to investigate the metastatic potential of KIM-1-expressing cells, and RNA-seq was conducted to identify differentially expressed genes between …

Improving Material Mapping In Glenohumeral Finite Element Models: A Multi-Level Evaluation, Nikolas K. Knowles

Electronic Thesis and Dissertation Repository

An improved understanding of glenohumeral bone mechanics can be elucidated using computational models derived from computed tomography data. Although computational tools, such as finite element analysis, provide a powerful quantitative technique to evaluate and answer a variety of biomechanical and clinical questions, glenohumeral finite element models (FEMs) have not kept pace with improvements in modeling techniques or model validation methods seen in other anatomic locations. The present work describes the use of multi-level computational modeling to compare, develop and validate FEMs of the glenohumeral joint.

Common density-modulus relationships within the literature were evaluated using a multi-level comparative testing methodology to …

The Group A Streptococci Bacteriocins Facilitate A Competitive Advantage During Nasopharyngeal Infection, Lana Estafanos

Electronic Thesis and Dissertation Repository

Pathogenic streptococci have evolved specific systems to eliminate bacterial competitors within their biological niche. In microbial environments, niche competition is often driven by the production of short antimicrobial peptides called bacteriocins; this provides a mechanism by which Streptococcus pyogenes may compete for ecological stability and establish infection. Recent findings from our laboratory have identified two novel Class IIb bacteriocin systems – Streptococcus pyogenes bacteriocin (Spb) JK and MN in the M18 serotype S. pyogenes strain MGAS8232 – that may contribute to nasopharyngeal infection. Here, we show that galactose and CO₂ are distinct regulatory cues which induce antimicrobial activity. Under …

Metabolic And Expression Changes Associated With A Mouse Model Of Intrauterine Growth Restriction (Iugr), Bethany N. Radford

Electronic Thesis and Dissertation Repository

Intrauterine growth restriction (IUGR) is a pregnancy condition where fetal growth is suboptimal, resulting in an infant born small for gestational age (<10th percentile) and is associated with metabolic disorders such as type 2 diabetes in adulthood. This study aims to understand tissue-specific adaptations to fetal undernutrition which predispose the individual to metabolic disorders in adulthood. A model of growth restriction in mice was established using 70% of maternal ad libitum total food (g) (E6.5-birth). At weaning, male offspring received standard chow or a HFHS diet. Body weight and random blood glucose levels were measured at 6 months. To assess metabolism at 6 or 7 months, glucose tolerance, pyruvate challenge and hepatic portal vein insulin challenge tests were administered and serum peptide markers for obesity and diabetes were measured. Metabolic cages were also used at 2 and 7 months to measure activity, food intake and respiratory exchange ratios (RERs). Adult liver, adipose and skeletal muscle and fetal liver was collected for RNA sequencing. Maternal nutrient restricted (MNR) offspring were growth restricted with disproportionately smaller fetal livers. 19% of standard chow-fed MNR offspring became glucose intolerant. On an isocaloric high-fat high-sugar diet no differences in MNR growth or glucose metabolism were detected. However, RERs were reduced at all timepoints in MNR on a HFHS relative to MNR on standard chow. Differences in transcription of genes involved in hypoxia signalling were detected and HIF-2a and HIF-3a proteins were increased in fetal liver of MNR offspring. Genes differentially expressed in the fetus were not differentially expressed at 6 months. Gene expression of metabolically regulatory transcripts in liver, adipose and skeletal muscle did not differ in all MNR and glucose intolerant MNR relative to controls. This model results in a susceptible and non-susceptible population of maternal nutrient restricted offspring and supports the concept of hypoxia signalling contributing to fetal adaptations. Understanding adaptations in hepatic hypoxia signalling in response to fetal undernutrition and how they vary in susceptible and unsusceptible populations will provide insight into how fetal nutrition can influence adult metabolism.

Proteomic Characterization Of Human Multipotent Stromal Cells Secreted Proteins With Therapeutic Potential For Β-Cell Regeneration, Miljan Kuljanin

Electronic Thesis and Dissertation Repository

Novel strategies to stimulate the expansion of β-cell mass in situ are warranted for diabetes therapy. Cell-replacement therapies for the treatment of diabetes have become a focal point in recent years. Endogenous regeneration of β-cell mass has been demonstrated using human multipotent stromal cells (hMSC). However, the secretory factors responsible for initiating endogenous regeneration remain unknown. Successful large-scale proteomic applications to address these questions have been limited in part by difficulties in correctly selecting the appropriate methodologies. Thus, the goal of this thesis was a combination of assessing different proteomic workflows to facilitate investigation into hMSC biology, applying these methods …

Exploiting Fission Yeast Genetic Interaction Data To Identify Disease-Specific Drug Targets For Tuberous Sclerosis Complex, Ashyad Rayhan

Electronic Thesis and Dissertation Repository

Tuberous sclerosis complex (TSC) is an inherited genetic disorder caused by loss-of-function mutations in either TSC1 or TSC2. Their respective gene products regulate the mechanistic target of rapamycin (mTOR) signaling pathway, which serves as an activator of cellular proliferation, metabolism, and cell survival. Orthologs of the TSC1 and TSC2 genes exist in a wide range of organisms, including the commonly used and genetically tractable model eukaryote, Schizosaccharomyces pombe. To better understand the functional roles of S. pombe tsc1 and tsc2, I exploited recent advances in genetic interaction biology to identify and characterize genes that modulate the phenotypic …

Retinoic Acid Pathway Inhibition To Expand Human Hematopoietic Progenitor Cells With Islet Regenerative Capacity, Ruth Elgamal

Electronic Thesis and Dissertation Repository

Cellular therapy to induce islet regeneration is emerging as a novel treatment strategy for diabetes. Umbilical cord blood (UCB)-derived hematopoietic stem/progenitor cells (HSPC) isolated by high aldehyde dehydrogenase activity (ALDH^hi) reduce hyperglycemia after transplantation into streptozotocin (STZ)-treated NOD/SCID mice. However, UCB-derived ALDH^hi cells are rare and expansion without the loss of regenerative function is required. We hypothesized that BMS 493, an inverse retinoic acid receptor agonist, will prevent HSPC differentiation of HSPC during expansion, generating more ALDH^hi cells for therapy. ALDH^hi cells expanded for 6 days with BMS 493 showed a 2.70-fold-increase in ALDH^{hi …}

The Effect Of Insulin Treatment And Exercise Modality On Skeletal Muscle Fiber Size In Streptozotocin-Induced Type 1 Diabetic Rats, John Z. Nickels

Electronic Thesis and Dissertation Repository

Severe Type 1 Diabetes Mellitus (T1DM) is known to have several negative effects on skeletal muscle mass, a condition known as diabetic myopathy. One of these effects is the atrophy of the glycolytic muscle fibers. However, the role of intensity of insulin treatment and exercise modality in attenuating this loss in fiber cross-sectional area (CSA) specifically has yet to be determined. The purpose of this investigation was to determine the effects of 12 weeks of differing intensity of insulin therapy and exercise modality on the CSA of plantaris muscle fibers, identified by myosin heavy chain (MHC) of STZ-induced T1DM rats. …

Investigating Stromal Contributions To The Regulation Of Cancer Progression, Krista M. Vincent

Electronic Thesis and Dissertation Repository

Tumours are not insular masses of proliferating cells, rather tumour cells evolve within a complex local environment complete with matrix, stromal, and immune components. Therefore, successful tumour growth and eventual metastasis is not determined solely by tumour cells themselves, but also by the fitness advantage or disadvantage conferred by their local environment. However, many of our current cancer models are composed solely of tumour cell isolates. As tumour fitness is dependent on the entire local cellular context, we were interested in characterizing the accuracy of cell lines as models of the tumour microenvironment, with a focus on the secreted Frizzled-related …

The Development Of Novel Imaging Modalities & High-Throughput Drug Screening Platforms In The Drosophila Melanogaster Model Of Human Calcium Oxalate Nephrolithiasis, Sohrab Naushad Ali

Electronic Thesis and Dissertation Repository

Nephrolithiasis is a common urological disorder. Despite advances in the surgical treatment of kidney stone disease, research into its prevention and medical management remain stagnant. This is due to lack of viable pre-clinical models to study the disorder. In this project, we develop and characterize a robust Drosophila melanogaster model for human calcium oxalate nephrolithiasis. Using this model, we have developed intravital imaging techniques to study stone formation and novel high-throughput drug screening platforms. We successfully demonstrate calcium oxalate stone formation by sodium oxalate and ethylene glycol supplementation, with subsequent intravital imaging using bisphosphonate based fluorescent probes. Screening of 360 …

Granulocyte Colony-Stimulating Factor: Its Role In Gut-Homing Macrophage Generation And Colitis, And Production By Probiotics, Shahab Meshkibaf

Electronic Thesis and Dissertation Repository

The pleiotropic cytokine granulocyte-colony stimulatory factor (G-CSF) is mainly required for the generation of neutrophils, but its role in macrophage generation has also been reported. In addition, G-CSF is effective for the down-regulation of inflammatory cytokines and ameliorating gut disorders, such as colitis. However, the G-CSF function in macrophage generation and gut immunity remains unclear. The first focus of this thesis was to assess the role of G-CSF in macrophage generation and its contribution to gut immunity. G-CSF was found to promote the generation of Gr-1high/F4/80+ macrophages in macrophage (M)-CSF-treated bone marrow cells, most likely through suppressing cell death. Gr-1high …

An Investigation Into The Combined Effects Of Β-Amyloid Toxicity And Cerebral Ischemia On The Pathological Expression Of Gangliosides., Jeffrey D. Hepburn

Electronic Thesis and Dissertation Repository

Identifying mechanisms underlying the synergistic pathological interaction between stroke and Alzheimer’s disease (AD) can effectively guide future therapeutic strategies for these highly co-morbid conditions. Aberrant ganglioside expression marked by the pathological accumulation of ganglioside GM3 is common to stroke and AD, yet it is unclear whether GM3 is synergistically enhanced in a comorbid model, or if GM3 is a viable therapeutic target. Adult male Wistar rats received a unilateral ischemic striatal infarct via endothelin-1 (ET-1) injection alone or in combination with bilateral intracerebroventricular injection of the β-Amyloid 25-35 peptide (Aβ) to induce generalized Aβ toxicity (Aβ/ET-1). Animals were sacrificed after …