Medical Physiology Commons^™

Noninvasive Quantification Of Tissue Sodium Concentration In The Kidney Disease Spectrum Using 23na Magnetic Resonance Imaging, Fabio R. Salerno

Electronic Thesis and Dissertation Repository

Chronic kidney disease (CKD), especially when requiring kidney replacement therapy (hemodialysis (HD) and peritoneal dialysis (PD)), is associated with extracellular water expansion with increased total body sodium. Sodium can also be accumulated in tissues independently of extracellular water. Sodium-23 magnetic resonance imaging (²³Na MRI) can quantify the concentration of sodium nuclei in tissues. Applied to the human leg, quantification of tissue sodium concentrations mainly at the skin and muscle level is possible. We hypothesized that increased tissue sodium concentrations exert toxic effects in CKD and dialysis. We aimed to (1) compare tissue sodium concentrations in adults, children and …

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 …

Piezo1: Proteins For Mechanotransduction And Integration Of Endothelial Shear Stress & Intravascular Pressure, Juan Garcia Robledo M.D.

Electronic Thesis and Dissertation Repository

Piezo proteins are transmembrane ion channels, specialized in detecting mechanosensitive stimuli and transduce mechanical forces into biochemical signals. Piezo proteins research has helped understand physiological mechanisms, but the integrative role that Piezo1 plays in the regulation of the microvasculature has remained unstudied. Our main objective was to characterize ex vivo microvascular responses to the blockade of Piezo1 mechanotransduction in male (n=29) and female (n=24) Sprague-Dawley (SD) rats. Gracilis arterioles (GA) and middle cerebral arterioles (MCA) were harvested for ex-vivo vessel preparations. After vessel viability confirmation, every vessel was submitted to myogenic and flow challenges under control conditions and after Grammostola …

Low Birth Weight And Post-Natal Diet Induced Alterations In Skeletal Muscle Oxygen Consumption And Fiber Type Composition, Megan Cedrone

Electronic Thesis and Dissertation Repository

Adverse in utero and postnatal conditions can increase susceptibility to metabolic syndrome (MS). Altered muscle respiration contributes to MS, but the effects of restricted oxygen and nutrients in utero on skeletal muscle mitochondria remain unknown. In this study guinea pig sows underwent uterine artery ablations mid-gestation, producing fetuses with low birth weight (LBW). Soleus muscle was collected near term or at four months of age, from LBW and control fetuses and offspring, where the offspring were fed either a Western Diet (WD) or a control diet (CD). Soleus muscles from LBW fetuses exhibit lower maximal respiration rates than normal birth …

The Purification Of Human Adult Progenitor Cell Types To Promote Angiogenesis, Stephen E. Sherman

Electronic Thesis and Dissertation Repository

Cellular transplantation strategies have aimed to combat critical limb ischemia (CLI) by inducing endogenous blood vessel regeneration. Transplantation of mesenchymal stromal cells (MSC) for CLI has proven safe and well-tolerated but demonstrated only modestly improved clinical outcomes explained in part by a lack of MSC survival and/or potency in ischemic tissues. This thesis focuses on the development of improved transplantation strategies for patients with CLI utilizing purified pro-angiogenic subsets of MSC and endothelial colony forming cells (ECFC) seeded within decellularized adipose tissue (DAT) bioscaffolds. First, I investigated whether purification of bone marrow-derived MSC based on a conserved stem cell function, …

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 …

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 …}

Cardiac Repair Post-Myocardial Infarction: Roles Of The Primary Cilium And The Long Non-Coding Rna Malat1, Jessica N. Blom

Electronic Thesis and Dissertation Repository

Complete occlusion of a coronary artery causes myocardial infarction (MI), resulting in cardiomyocyte cell death. The surviving myocardium undergoes a deleterious remodeling process which causes further injury, and can ultimately result in heart failure. Despite therapeutic advances that have prolonged life, MI remains a leading cause of death worldwide and imparts a significant economic burden. The advancement of treatments to improve cardiac repair post-MI requires the discovery of new targeted treatment strategies. Epicardial-to-mesenchymal transition (EMT) occurs post-MI as a mechanism to support neovascularization and cardiac healing. However, the endogenous EMT is not enough to support sufficient repair. The transcription factor …

Exercise Protects Against Congenital Heart Defects Induced By Pregestational Diabetes, Tana Saiyin

Electronic Thesis and Dissertation Repository

Pregestational diabetes is a risk factor for birth defects, with diabetic women having a four times higher risk of producing children with congenital heart defects (CHDs). This is concerning because the prevalence of diabetes is growing at epidemic proportions. The purpose of this thesis is to investigate whether exercise can also reduce hyperglycemia-induced CHDs and determine the underlying mechanism. Endothelial nitric oxide synthase (eNOS) is a critical enzyme for normal cardiogenesis that can be upregulated with exercise in adult cardiovascular tissue. However, whether maternal exercise can regulate fetal eNOS and affect heart development has yet to be studied. In this …

Maternal Nutrient Restriction With Fetal Growth Restriction In Guinea Pigs Impacts Brain Development And Neuroimaging Correlates In Neonatal Offspring, Catherine Nevin

Electronic Thesis and Dissertation Repository

Aberrant brain development in utero accompanied by fetal growth restriction (FGR) increases the risk of neurodevelopmental disorders in later life. However there are limited non-invasive biomarkers in the brain for the early identification of said neurodevelopmental disorders in an animal model of FGR. Guinea pig sows were fed either ad libitum (Control) or 70% of the control diet pre-pregnancy, increasing to 90% at mid-pregnancy (MNR) creating appropriately grown (AGA) Control and FGR-MNR neonates, respectively. Three to four weeks corrected post-natal age, neonates were imaged using magnetic resonance imaging (MRI) and spectroscopy (MRS) techniques, and were killed 48-72 hours later for …

Characterization Of The Nicotine-Induced Endoplasmic Reticulum Stress Response In The Rat Placenta In Vivo And In Vitro, Michael Ka Chun Wong

Electronic Thesis and Dissertation Repository

Nicotine exposure during pregnancy leads to adverse health outcomes, including compromised placental development. Although the molecular mechanisms remain elusive, recent studies identified that endoplasmic reticulum (ER) stress may underlie poor placentation. Therefore, we were interested in investigating the effects of nicotine exposure on the ER stress response in the placenta. A well-established maternal nicotine exposure rat model and Rcho-1 trophoblast giant cell model were utilized to address the research questions. Maternal nicotine exposure in vivo led to elevated ER stress in association with impaired disulfide bond formation and hypoxia. Nicotine exposure in vitro further differentiated that ER stress may be …

Inhibition Of Elongation Factor 1a-1 Activity And Hepatic Lipotoxicity, Alexandra Margaret Anne Hetherington

Electronic Thesis and Dissertation Repository

Elongation factor 1A-1 (eEF1A-1) was previously identified as a mediator of fatty acid-induced cell death (lipotoxicity) downstream of endoplasmic reticulum (ER) stress. Furthermore, inhibition of the peptide elongation activity of eEF1A-1 with the cyclic depsipeptide didemnin B (DB) diminishes ER stress and lipotoxicity in cultured hepatocytes. Since ER stress is involved in nonalcoholic fatty liver disease (NAFLD), it was hypothesized that administration of DB to obese mice with NAFLD would reduce hepatic lipotoxicity. Treatment with DB for one week improved several parameters associated with hepatic lipotoxicity and modestly decreased food intake without evidence of illness. Liver triglycerides and protein markers …

Kiss1r Signaling Promotes Breast Cancer Drug Resistance, Alexandra J. Blake

Electronic Thesis and Dissertation Repository

Kisspeptins signal via the G-protein coupled receptor, KISS1R, and act as metastasis suppressors in numerous cancers. In estrogen receptor (ERα)-negative breast cancer cells, however, KISS1R signaling promotes cell invasion by activating the epidermal growth factor receptor (EGFR). Unfortunately, clinical success of anti-EGFR therapeutics has been limited, as patients often develop drug resistance. Recently, another receptor tyrosine kinase, AXL, has been shown to promote breast cancer drug resistance. We hypothesize that KISS1R promotes EGFR expression and induces breast cancer drug resistance. We demonstrated that KISS1R increases EGFR transcription, by increasing SP-1 binding to the EGFR promoter, as demonstrated by chromatin immunoprecipitation …

Timp3 Regulation Of Macrophage Activation And Apoptosis, Michael S. Brock

Electronic Thesis and Dissertation Repository

Acute respiratory distress syndrome (ARDS) is a lung disease involving profound inflammation. Origins of persistent inflammation in select cases of ARDS are poorly understood, and we propose persistent inflammatory macrophages may be one of its mechanisms. Macrophages polarize to either promote inflammation, or suppress inflammation. Tissue inhibitor of metalloproteinases 3 (TIMP3) reduces the pro-inflammatory polarization in macrophages. Additionally, studies have shown TIMP3 promotes apoptosis, and its absence delays recovery from bleomycin-induced lung injury.

We hypothesize that TIMP3 promotes apoptosis of murine macrophages through inhibition of metalloproteinase activity and stabilization of FAS on the cell surface. Pro-inflammatory Timp3^-/- bone marrow-derived …

Mouse Models Of Intervertebral Disc Development, Degeneration And Mechanical Loading, Matthew R. Mccann

Electronic Thesis and Dissertation Repository

Intervertebral disc (IVD) degeneration is a complex and multi-factorial process that is influenced by aging, genetic predispositions and environmental influences, such as altered mechanical loading. While recent studies have begun to characterize changes in the IVD associated with degeneration, the underlying etiology remains elusive. It is thought that the loss of notochord cells from the nucleus pulposus (NP) is one initiating factor contributing to the cascade of disc degeneration. However, questions remain about the function of notochord cells within the disc, including their capacity as tissue specific progenitor cells for the nucleus pulposus. We have demonstrated, with the use of …

Tak1 Mediates Tgf Beta-1 Responses In Gingival Fibroblasts, Hanna Kuk

Electronic Thesis and Dissertation Repository

In fibroblasts, transforming growth factor β-1 (TGFβ1) signals via canonical and non-canonical pathways to promote wound healing or hyper-contractile responses resulting in scars. The oral cavity however does not scar and fibrotic responses such as gingival hyperplasia are characterized by a hyper-proliferative response. The involvement of non-canonical, TGFβ-activated kinase-1 (TAK1) - mediated TGFβ1 signaling in gingival fibroblasts has not been previously examined. Here I show that TAK1 selective inhibitor (5Z)-7-Oxozeaenol blocks TGFβ1-induced expression of wound healing and fibrotic marker CCN2 (connective tissue growth factor) in gingival fibroblasts. Genome-wide expression profiling revealed that essentially all TGFβ1 induced genes were in fact …

Er Stress Coupled Pannexin Channel Activation Via Stim Proteins, Ankur Bodalia

Electronic Thesis and Dissertation Repository

Many neurodegenerative diseases, including Alzheimer’s Disease, are associated with ER stress. It is suggested that plasma membrane channels contribute to the increased ionic influx and subsequent cell death in response to ER stress. Pannexin channels, which have been implicated in various pathophysiological conditions, are a suitable candidate for facilitating this response. However, mechanisms of pannexin channel activation are poorly defined. I investigated the potential regulation of pannexin activity by the ER stress sensor, STIM. It was hypothesized that pannexin channel activation during ER stress is contingent on the recruitment of STIM proteins. In neurons, pannexin activation was observed in response …

Fetal And Neonatal Exposure To Nicotine Augments Hepatic Fatty Acid Synthesis In Rat Offspring Long-Term, Noelle L. Ma

Electronic Thesis and Dissertation Repository

While nicotine replacement therapy (NRT) is presumed to be a safer alternative to smoking in pregnancy, the long-term consequences in offspring are still largely unknown. Animal studies now suggest that maternal nicotine exposure during pregnancy and lactation (MNE-PL) leads to a wide variety of adverse outcomes for the offspring, including increased adiposity. The focus of this study was to investigate how MNE-PL in rats may lead to liver dysfunction long-term in offspring through alterations in gene expression and epigenetic modifications. Postnatal day 180 (PND180) offspring exposed to nicotine during pregnancy and lactation (1mg/kg/day) exhibited increased circulating and hepatic triglycerides concomitant …

Characterizing Stomatin-Like Protein 2 And Its Role In Neuron Survival, Lisa A. Foris

Electronic Thesis and Dissertation Repository

Stomatin-like Protein 2 (SLP-2) has been identified as a stress-inducible transcript and has been shown to interact with and stabilize mitochondrial proteins. Since mitochondria are critical for neuronal function, we hypothesized that SLP-2 regulates neuron survival in response to stressful stimuli. A conditional SLP-2 knockout mouse (deletion) and the SN56 cell line (upregulation) were employed to study the role of SLP-2 in mitochondrial dynamics and neuron survival. SLP-2 deficient primary cortical neurons displayed significantly decreased levels of various mitochondrial respiratory chain proteins, indicating SLP-2 contributes to maintenance of mitochondrial membrane integrity. SLP-2 was up-regulated in response to oxidative stress and …

Investigating Adenosine’S Role In Controlling The Cerebral Metabolic Rate Of Oxygen Following Hypoxia-Ischemia, Mustafa Ridha

Electronic Thesis and Dissertation Repository

The cerebral metabolic rate of oxygen (CMRO2) has been shown to be an early indicator of hypoxia-ischemia (HI); however, the mechanisms controlling post-HI CMRO2 are not clear. One potential mechanism is the activation of the adenosine A1 receptor due to increased adenosine concentrations during the insult. The present study investigated if the specific adenosine A1 antagonist, DPCPX, would reduce the typical reduction in CMRO2 and electrical cortical activity following HI. Measurements of CMRO2 and electrical cortical activity were obtained on piglets by near-infrared spectroscopy (NIRS) and amplitude-integrated electroencephalography (aEEG), respectively. The post-HI measurements of CMRO2 and mean aEEG background voltage …

Roles Of Pgc-1Α/Ppars Pathway In Regulating Insulin Sensitivity In Mouse Skeletal Muscle Cells Under Prolonged Hypoxia, Yunyan Zhang

Electronic Thesis and Dissertation Repository

Using the C₂C₁₂ mouse myoblast cell line, I investigated how prolonged hypoxia affected components of the insulin signalling and FAO/PGC-1α/PPARs pathways, as they might impact insulin sensitivity in skeletal muscle cells.

Hypoxia resulted in lower p-Akt (Thr 308) and higher total cellular GLUT4 protein levels after 7 days of differentiation. This coincided with higher triglyceride content and alterations of the FAO/PGC-1α/PPARs components, both of which could contribute to the changes observed in the components of the insulin signalling pathway. Specifically, cells differentiating in 1% O₂ had lower SIRT1, PPAR- α, FATP4 and MCAD mRNA; accompanied by …

Gender Does Not Influence The Relationship Between Posterior Cruciate Ligament Design And Patient-Reported Outcomes In Patients Receiving Primary Unilateral Total Knee Arthroplasty, Ryan Milan

Electronic Thesis and Dissertation Repository

The effect of the interaction between gender and posterior cruciate ligament (PCL) prosthesis design on patient-reported outcomes is an understudied area of research. We evaluated 1613 patients, from the Ontario Joint Replacement Registry (2001-2006), who underwent primary total knee replacement. This study investigated the impact of the gender-PCL design interaction on Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) change scores and patient satisfaction, by performing linear regression analysis, using full-adjusted models that also included the gender-PCL prosthesis design interaction variable. PCL prosthesis design did not affect WOMAC change scores or satisfaction (p>0.05). Moreover, Gender did not influence either …

Methodological Challenges And Clinical Applications Of Hair Cortisol Analysis, Evan W. Russell

Electronic Thesis and Dissertation Repository

This thesis examines methodological and clinical aspects of hair cortisol analysis. The methodological study examines the role of sweat as a contributor to hair cortisol concentrations. Hair cortisol analysis is an effective measure of chronic stress. Cortisol is assumed to enter the hair via blood, sebum, and sweat, however the extent to which sweat contributes to hair cortisol content was unknown. This study concluded that human sweat contains cortisol that likely contributes to hair cortisol content. Subjects with prolonged sweating at the time of hair collection may have increased hair cortisol concentrations that cannot be decreased with conventional laboratory washing …