Medicine and Health Sciences Commons^™

Investigating A Novel Receptor That Mediates Vasoconstriction In Mouse Femoral Arteries, Joselia Carlos

Electronic Thesis and Dissertation Repository

The synthetic peptide trans-cinnamoyl-leucine-isoleucine-glycine-arginine-leucine-ornithine-amide (tcLIGRLO) causes smooth muscle contraction in mouse femoral arteries. The identity of the receptor that mediates this response is undetermined. We hypothesize that the novel mechanism for tcLIGRLO-induced contractions involves a G-protein coupled receptor (GPCR) and a G_q-Ca²⁺ signalling pathway. Chapter 2 describes experiments using femoral arteries isolated from male and female systemic protease-activated receptor 2 (PAR2KO) mice (n=31; 21 – 39 weeks of age) using tcLIGRLO and the G_q-inhibitor, YM-254890 (YM). Contractions produced by tcLIGRLO did not differ by sex but decreased as age increased. YM inhibited tcLIGRLO-induced contractions. Chapter …

Applications Of Genetic Testing For Endocrine And Metabolic Disorders, Amanda Berberich

Electronic Thesis and Dissertation Repository

Knowledge of inherited diseases and the ability to rapidly, efficiently and comprehensively perform genetic testing are advancing steadily. However, the ideal approach to translate this ability into clinical applications for endocrine disorders has yet to be determined. This work focuses on aspects of clinically translating knowledge of select heritable endocrine and metabolic conditions.

For maturity onset diabetes of the young (MODY), a monogenic disorder with no current consensus guidelines governing testing procedures, this work addresses methods to improve detection by validating the use of next generation sequencing-based techniques to identify MODY cases and to detect copy number variations.

For very …

Endothelial Dysfunction In Hindlimb Arteries Of Old Sprague Dawley Rats, And The Type 2 Diabetic Zucker Diabetic Sprague Dawley Strain., Andrea N. Wang

Electronic Thesis and Dissertation Repository

Ageing, and type 2 diabetes are associated with cardiovascular diseases and endothelial dysfunction. Endothelial dysfunction is characterized by a decline in endothelium-mediated vasodilation. In this thesis, we determined the vascular function of hindlimb arteries supplying skeletal muscle and extremities using isolated arteries and wire myography. For ageing studies, we used Sprague Dawley rats and for type 2 diabetes we used the Zucker Diabetic Sprague Dawley strain. Vasodilation of hindlimb arteries with acetylcholine were impaired in both models. However, protease-activated receptor 2 mediated vasodilation was upregulated in arteries. Evidence of non-nitric oxide mechanisms were also found in peripheral vasculature. These data …

A Characterization Of Rgnef Biophysical Properties And Interactome, Brooke E. Wile

Electronic Thesis and Dissertation Repository

ALS is a progressive and fatal neurodegenerative disorder whose pathologic hallmark is the presence of neuronal cytoplasmic inclusions (NCIs). In approximately 97% of ALS cases, NCIs are found to be TDP-43+. Rho-guanine nucleotide exchange factor (RGNEF) has recently been implicated in ALS pathophysiology through its co-localization and coimmunoprecipitation with TDP-43+. RGNEF has also been shown to harbour cytoprotective effects in the N-terminal region and is responsible for the regulation of low molecular weight-neurofilament (NFL), intimately involved neural structure, through its predicted RNA-binding domain (RBD). This study looked to purify constructs of RGNEF through nickel immobilized metal affinity chromatography (Ni-IMAC) and …

Mechanisms Underlying Enhanced Bone Marrow Adipogenesis In Diabetes, Jina J.Y. Kum

Electronic Thesis and Dissertation Repository

Morbidity and mortality associated with diabetes are due to secondary vascular complications that include both micro- and macro-vascular organ dysfunctions. Our recent studies show that vascular dysfunction and inadequate vessel repair in diabetes may potentially be due to impaired vasculogenesis (de novo vessel formation). Specifically, we have shown that diabetes enhances adipogenesis in the bone marrow and reduces the number of marrow-resident vascular regenerative stem cells. In this study, I have determined the mechanisms of deleterious bone marrow adipogenesis, which may alter the cellular composition of the marrow and lead to the depletion of vascular regenerative stem cells.

My …

Creating Tools To Study The Signaling And Function Of The Adhesion Family Of Gpcrs, Victor M. Mirka

Electronic Thesis and Dissertation Repository

Adhesion GPCRs (aGPCRs) are difficult to study because they are activated by mechanical force. aGPCRs are autoproteolytically cleaved into N-terminal and C-terminal fragments. Mechanical force removes the N-terminal fragment revealing a tethered ligand activating the receptor. Proteinase Activated Receptors (PARs) are N-terminally cleaved by proteinases revealing a tethered ligand activating the receptor. We hypothesized the tethered ligand of aGPCRs could be revealed by replacing the N-terminal fragment with a PAR N-terminus. We fused the PAR2 N-terminus to the C-terminal fragments of four aGPCRs: CD97, EMR2, GPR56, and BAI1. PAR2-aGPCR chimeric receptors dose dependently recruited G-proteins and β-arrestins, supporting our hypothesis. …

Investigating Bone Cement Susceptibility Related Artifacts And Adhesion, Eric Kuindersma

Electronic Thesis and Dissertation Repository

Blood Oxygen Level Dependent (BOLD) functional Magnetic Resonance Imaging (fMRI) utilizes pulse sequences sensitive to changes in concentration of deoxyhemoglobin to indirectly measure neural activity. Sequences used for BOLD are sensitive to magnetic susceptibility differences that may cause signal voids. Our lab has designed an awake marmoset head coil that eliminates confounds associated with imaging an animal under anesthesia. This design requires a head chamber attached to an animal’s skull with a cement that may cause a susceptibility artifact. Motivation behind this project was to find an MRI compatible cement that remains secure to the skull with minimal artifacts. Four …

The Role And Importance Of Social Support During Recovery Following Distal Radius Fracture, Ogheneruona Mi Idoghor Ikpen

Electronic Thesis and Dissertation Repository

This thesis explored how social support changes with time and differs across genders within 1-year post distal radius fracture (DRF). It also examines the effect of social support on the patient-rated wrist evaluation (PRWE) score and health-related quality of life (HRQoL) of DRF patients at 3 months post-fracture. In this cohort study, patient-reported social support (emotional/informational, tangible, affectionate and positive social interaction) was measured using the Medical Outcomes Study (MOS) social support survey, and HRQoL was measured using the 36-Item Short-Form Survey (SF-36). Social support significantly decreased at 3 months in comparison to baseline, 6 months and 1 year (with …

Validation Of Arterial Spin Labeling For Longitudinal Monitoring And Differential Diagnosis Of Frontotemporal Dementia, Tracy Ssali

Electronic Thesis and Dissertation Repository

Frontotemporal dementia (FTD) is a devastating neurodegenerative disease characterized by a rapid decline in behavioural, language, and motor abilities. Advances in the understanding of FTD genetics and pathophysiology, and the subsequent development of novel disease modifying treatments have highlighted the need for tools to assess their efficacy. While structural magnetic resonance imaging (MRI) and functional imaging with ¹⁸F-flurodeoxyglucose (FDG) positron emission tomography (PET) are used for clinical diagnosis, structural changes are subtle at the early stages and PET imaging is expensive and access limited. Given the coupling of cerebral blood flow (CBF) to energy metabolism, an attractive alternative is …

Free Fatty Acid Treatment Alters Autophagy During Mouse Preimplantation Embryo Development, Zuleika C. L. Leung

Electronic Thesis and Dissertation Repository

Obesity-induced hyperlipidemia is one of the main factors for female infertility. Hyperlipidemia, specifically with high levels of palmitic acid (PA) and oleic acid (OA), interferes with preimplantation development. Autophagy is essential in early embryo development but, it is unknown whether hyperlipidemia affects autophagic mechanisms in preimplantation embryos. It was hypothesized that PA will alter autophagy in preimplantation mouse embryos and that the subsequent effects will be reversed by OA. PA impaired blastocyst development by arresting embryos at the 8-cell stage. PA also elevated early embryo autophagy by increasing autophagosome formation, decreasing maturation, and disrupting degradation. Co-treatment with OA showed developmental …

Exogenous Surfactant As A Delivery Vehicle For Intrapulmonary Therapeutics, Brandon J. Baer

Electronic Thesis and Dissertation Repository

As an organ system, the lung has unique advantages and disadvantages for direct drug delivery. Its contact with the external environment allows for the airways to be easily accessible to intrapulmonary delivery. However, its complex structure, which divides into more narrow airways with each branch, can make direct delivery to the remote alveoli challenging. The objective of this thesis was to overcome this issue by using exogenous surfactant, a lipoprotein complex used to treat neonatal respiratory distress syndrome, as a carrier for pulmonary therapeutics. It was hypothesized that therapeutics administered with a surfactant vehicle would display enhanced delivery to the …

Is There An Increased Risk Of Delirium Among Patients With Overactive Bladder Treated With Newer Anticholinergic Medication Compared To A Beta-3 Agonist?, Khaled Ashraf Etaby

Electronic Thesis and Dissertation Repository

ABSTRACT

Objective

To determine if there is an increased risk of delirium among patients with overactive bladder (OAB) started on anticholinergic medication compared to beta-3 agonist.

Methods

We conducted a population-based, retrospective, matched weight cohort study using administrative data from Ontario, Canada from January 2016 until March 2020. We matched 13865 new users of Oxybutynin to 33097 new users of newer anticholinergic medications (Solifenacin, Tolterodine, Trospium, Darifenacin and Fesoterodine), and to 56062 new users of beta-3 agonist medication (Mirabegron); all of the included medications are only for the treatment of OAB. Matching weights (an extension of the propensity score weighting) …

Erythrokeratodermia Variabilis Et Progressiva (Ekvp) Linked Cx30.3 Mutants Can Be Selectively Rescued By Co-Expression Of Wildtype Keratinocyte Connexins, Rhett O. Figliuzzi

Electronic Thesis and Dissertation Repository

Connexin 30.3 (Cx30.3) is a β-connexin encoded by GJB4 that is key in epidermal homeostasis. Eleven mutations to the GJB4 are linked to an autosomal dominant skin disease called erythrokeratodermia variabilis et progressiva (EKVP). These mutations remain largely uncharacterized, limiting therapeutic options. In this study, we characterize the expression and functional status of three EKVP-linked Cx30.3 mutants, G12D, T85P and F189Y in rat epidermal keratinocytes. We found that EKVP-linked Cx30.3 mutants were not functional due to their retention in the endoplasmic reticulum (ER), but did not upregulate BiP, an indicator of ER stress. Sub-physiological incubation and chemical chaperones (such as …

Frequency Dependent Diffusion Kurtosis Measurement In The Human Brain With Oscillating Gradients, Kevin B. Borsos

Electronic Thesis and Dissertation Repository

Oscillating gradient spin-echo (OGSE) is an implementation of diffusion MRI that enables shorter effective diffusion times than the conventional pulse gradient spin-echo (PGSE) by periodically modulating the diffusion gradient. Measurements of the diffusion kurtosis, which reflects the degree of restricted diffusion, have previously been prohibited with OGSE due to technical limitations of clinical gradient systems. This thesis presents a novel oscillating gradient waveform that enables the measurement of kurtosis using OGSE without requiring advanced gradient hardware. Decreases of kurtosis are observed in OGSE acquisitions of healthy human subjects relative to PGSE, demonstrating the dependence of the kurtosis on oscillation frequency. …

The Genetic Landscape Of Neurodegenerative And Cerebrovascular Disease Phenotypes., Allison A. Dilliott

Electronic Thesis and Dissertation Repository

Neurodegenerative diseases are progressive, incurable conditions characterized by neuronal degeneration and protein aggregation, resulting in cognitive decline and/or motor dysfunction. Over half a million Canadians are affected with these diseases, and the number of cases is expected to rise as the aging population grows and average lifespans continue to increase. There are currently no curative treatments, and only few therapeutics are available to target disease symptoms or slow disease progression. Further, diagnosis can be challenging, relying on clinical features that are often highly heterogeneous between patients. Gaining a greater understanding of the full spectrum of genetic factors contributing to these …

The Antimicrobial Properties Of Exogenous Copper In Human Synovial Fluid Against Staphylococcus Aureus: An In-Vitro Study, Fernando Diaz Dilernia

Electronic Thesis and Dissertation Repository

We sought to analyse the antimicrobial properties of exogenous copper in human synovial fluid against Staphylococcus aureus. We performed several in-vitro growth and viability assays to determine the capability of multiple S. aureus strains to survive in synovial fluid under different growth conditions. S. aureus UAMS-1 significantly died at 24 hours (p=0.017), and S. aureus USA300 WT survived at 24 hours. We confirmed a high sensitivity to killing with the addition of exogenous copper on both strains at 4 (p=0.011), 12 (p=0.011), and 24 hours (p=0.011). Both WT and CopAZB-deficient USA300 strains significantly died in synovial fluid, evidencing a …

Cerebrovascular Compliance In Humans, Marcy Erin Moir

Electronic Thesis and Dissertation Repository

Pulsatile blood flow consists of two components: steady flow and oscillatory flow. Steady blood flow is primarily regulated by vascular resistance while vascular compliance represents a key mediator of oscillatory blood flow. However, most studies investigating the regulation of cerebral blood flow in humans have focused on vascular resistance. Recently, emerging evidence has implicated vascular compliance as an important contributor to the regulation of cerebral perfusion. Therefore, the research contained herein aimed to i) quantify cerebrovascular compliance responses to blood pressure alterations and ii) explore mechanisms regulating cerebrovascular compliance in humans. The studies employed a Windkessel modelling approach to calculate …

Delineating The Skeletal Muscle-Microvessel Regeneration Program After Ischemic Injury, Jason J. Lee

Electronic Thesis and Dissertation Repository

Understanding the cellular processes involved in skeletal muscle regeneration after damage is critical to advancing translational efforts toward the development of targeted therapeutics. The purpose of this thesis was to ascertain the dynamic interplay between regenerating muscle and regenerating blood vessels after ischemic injury.

First, using a novel systematic investigation of a widely used preclinical mouse model of limb ischemia, I generated a detailed atlas of muscle injury zones and angiogenesis zones in C57BL/6 mice subjected to femoral artery excision. This uncovered previously unrecognized regional variability and an exclusive relationship between angiogenesis and actively regenerating muscle zones. Then, an unbiased, …

Maternal Lifelong Western Diet Consumption Impacts Placental And Brain Development In The Term Guinea Pig Fetus, Carlene H. Cihosky

Electronic Thesis and Dissertation Repository

Both metabolic and cognitive dysfunction can originate from fetal reprogramming precipitating from adverse conditions experienced in utero. Of note is the western diet (WD), which is associated with maternal energy imbalances that may hinder fetal development through altered placental function. Brain-derived neurotrophic factor (BDNF), a growth factor that supports the placenta and developing brain, is responsive to such energy imbalances. This study sought to investigate the impact of lifelong maternal WD consumption on fetoplacental development, focusing on relations between placental changes, and fetal growth and neurodevelopment in a guinea pig model. Maternal WD consumption resulting in a lean metabolically …

Describing Functional Brain Connectivity's Role In The Relationship Of Multimodal Interventions To Improve Cognitive And Physical Function In Vulnerable (Frailty & Mild Cognitive Impairment) Older Adults., Nicholas (Nick) W. Bray

Electronic Thesis and Dissertation Repository

Aging is associated with declining cognitive and physical function. The decline accelerates in older adults diagnosed with mild cognitive impairment (MCI), a pre-dementia state, and frailty, a state of decreased physiological reserve. Previous work shows that frailty modifies the relationship between dementia pathology and clinical symptoms. Functional brain network connectivity (FBNC) refers to brain areas that are anatomically separate but temporally related in their neural signaling; it is believed to enable the completion of complex cognitive and physical functions. FBNC is considered a sensitive biomarker for monitoring the progression of dementia syndromes and investigating the efficacy of interventional strategies. Therefore, …

Measuring Inflammation In The Entire Myocardium In A Canine Model Of Myocardial Infarction With Hybrid Pet/Mri, Benjamin Wilk

Electronic Thesis and Dissertation Repository

Background: After myocardial infarction (MI), fibrosis and an ongoing dysregulated inflammatory response are associated with adverse cardiac remodeling. Fluorodeoxyglucose (FDG) positron emission tomography (PET) is sensitive to inflammation provided suppression protocols are implemented to restrict the uptake of glucose in myocytes. Magnetic resonance imaging can be used to determine extracellular volume, a surrogate measure of fibrosis. In some cases, patients present with markedly reduced flow in the setting of a large infarct, i.e. microvascular obstruction, restricting the delivery of FDG and contrast agents. To overcome this problem, a constant infusion was explored as an alternative to the clinical standard bolus …

Three-Dimensional Ultrasound Imaging For Quantifying Knee Cartilage Volume, Samuel Papernick

Electronic Thesis and Dissertation Repository

Arthritis is the most common chronic health condition in Canada, with the most common form being osteoarthritis (OA). There is a great clinical need for an objective imaging-based point-of-care tool to assess OA status, progression, and response to treatment. This thesis aims to validate a handheld mechanical three-dimensional (3D) ultrasound (US) device against the current clinical standard of magnetic resonance imaging (MRI) for quantifying femoral articular cartilage (FAC) volume. Knee images of 25 healthy volunteers were acquired using 3D US and 3.0 Tesla MRI scans. Two raters manually segmented the trochlear FAC during separate sessions to assess intra- and inter-rater …

Computer-Assisted Lesion Classification And Intervention Planning For Prostate Cancer, Ryan M. Alfano

Electronic Thesis and Dissertation Repository

Multi-parametric magnetic resonance imaging (mp-MRI) is emerging as a useful tool for classifying prostate cancer (PCa); however, it suffers from two major limitations: (1) complex, multi-dimensional signals make interpretation challenging and (2) inter-observer variability of lesion classification between physicians. Critically needed are methods for augmenting the interpretability of mp-MRI to assist in lesion classification. To meet this need, we leveraged a patient cohort with post-surgery pathologist-annotated transverse histology images registered to pre-surgery in-vivo mp-MRI with a measured target registration error. We developed a radiomics-based machine learning model trained on annotations for PCa vs. non-PCa, and found that a 5-feature Naïve-Bayes …

In Vivo Detection Of Car-T Cell Immunotherapy Using 3 Tesla Fluorine-19 Mri, Veronica Dubois

Electronic Thesis and Dissertation Repository

Chimeric antigen receptor (CAR) T cell therapy is an emerging cancer treatment that has shown remarkable success in the treatment of B cell malignancies. However, this therapy still has the potential to cause severe toxicities or poor treatment responses in some patients. An imaging tool for tracking CAR-T cells could provide important patient-specific data on CAR-T cell fate. In chapter 2, fluorine-19 magnetic resonance imaging (¹⁹F MRI) was evaluated as a method to track the location of ¹⁹F perfluorocarbon (PFC) labeled CAR-T cells non-invasively in a mouse model of B cell leukemia. We show for the first …

Mri Of Structural & Functional Changes Associated With Western Diet Consumption, Lauren M. Smith

Electronic Thesis and Dissertation Repository

The Western diet (WD) is a high-fat, high-sugar diet increasingly common in the Western world and is associated with adverse effects in many organs, though the mechanisms behind these changes are unclear. Magnetic resonance imaging (MRI) techniques that provide structural and functional information non-invasively were used to investigate the effect of the WD on the liver and placenta in a guinea pig model.

The WD leads to a manifestation of the metabolic syndrome in the liver known as non-alcoholic fatty liver disease (NAFLD). Fat-fraction MRI was used to confirm the onset of NAFLD in a guinea pig model fed a …

Testing A Novel Peptide-Infused Cream For Treatment Of Rheumatoid Arthritis In Dr4tg Mice, Alisha J. Moynahan

Electronic Thesis and Dissertation Repository

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease that causes joint pain and damage. Studies have shown that inducing immune tolerance towards RA-specific proteins/peptides in RA mouse models can reduce arthritis severity and pro-inflammatory responses. The objectives of this study were to determine if a novel peptide cream treatment could modify RA-specific immune responses and reduce joint swelling in a humanized mouse model expressing the HLA-DRB1*0401 allele (known as DR4tg mice), the strongest genetic risk-factor for RA. Hyaluronan-Phosphatidylethanolamine cream infused with synthetic peptides HomoCitJED and CitJED was applied to HomoCitJED-immunized DR4tg mice before or after arthritis induction. Knee joint …

Differential Effects Of Kim-1 In Subcutaneous And Orthotopic Renca Models Of Kidney Cancer, Demitra M. Yotis Dy

Electronic Thesis and Dissertation Repository

Renal Cell Carcinoma (RCC) is the most common and fatal type of kidney cancer. Over 30% of patients that are diagnosed with RCC exhibit metastases. Almost 88% of patients with distant metastases succumb to the disease within 5 years of diagnosis. Kidney Injury Molecule-1 (KIM-1) is a cell surface glycoprotein that is not expressed in a healthy kidney but becomes highly expressed on proximal tubular epithelial cells (PTECs) following injury. Data from the Cancer Genome Atlas (TCGA) reveals that >90% of RCC tumours express KIM-1 mRNA and that higher expression levels correlate with increased overall survival rates of patients. The …

Protein Misfolding Toxicity And Inclusion Formation In Cellular Models Of Neurodegeneration, Sonja E. Di Gregorio

Electronic Thesis and Dissertation Repository

Protein misfolding characterizes most neurodegenerative diseases. Protein misfolding is the conversion of specific proteins from their normal, often soluble, and native three-dimensional conformation into an aberrant, often insoluble, non-functional conformation. Protein inclusions and aggregates are among the major pathological hallmarks of protein misfolding associated with many neurodegenerative diseases. Yet, the role of aggregates and inclusions is not clearly defined and heavily debated. This study utilizes powerful genetic approaches in yeast and verification in mammalian neuronal cell lines to address the misfolding and toxicity of three proteins, the Rho Guanine Nucleotide Exchange Factor (RGNEF), Matrin3, which are involved in amyotrophic lateral …

Hiv-1 Drug Resistance To Integrase Strand Transfer Inhibitors In Hiv-1 Non-B Subtypes, Emmanuel Ndashimye

Electronic Thesis and Dissertation Repository

Human immunodeficiency syndrome (HIV-1) has infected over 75 million people and over 35 million have succumbed to virus related illnesses. Despite access to a variety of antiretroviral therapy (ART) options, ART programs have been disproportionally spread in the world with low-and middle-income countries (LMICs) facing challenges to access the most potent ART options. With less potent ART remaining in use in LMICs, HIV-1 drug resistance (HIVDR) presents a growing challenge in LMICs. Since approval of the first-generation integrase strand transfer inhibitor (INSTIs), Raltegravir (RAL) in 2007, INSTIs remain the best choice as a backbone of ART. Access to second generation …

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 …