Life Sciences Commons^™

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 …

Magnetic Field Frequency-Response For Human Magnetophosphene Perception And Associated Eeg Modulations, Cadence M. Baker

Electronic Thesis and Dissertation Repository

Background: Magnetophosphenes are among the most reliably reported effects resulting from magnetic induction. The frequency dependence of the perception threshold is crucial, as guideline agencies use this information to set exposure limits whose purpose is to protect public and workers.

Objective:Establish the magnetophosphene perception thresholds throughout the extremely low frequency range (0-300 Hz) and evaluate the use of EEG as a biomarker.

Hypothesis:Perception thresholds will be lowest at ~30 Hz. EEG occipital alpha power will decrease upon perception.

Methods:60 participants were exposed to homogenous magnetic fields up to 300 Hz, and 70 mT. EEG alpha power …

Cardiodynamic Associations With Resilience In Undergraduate Students And The Effect Of A Mentorship Intervention, Rachel J. Knetsch

Electronic Thesis and Dissertation Repository

The National College Health Assessment (NCHA) indicates that a majority of Canadian university students report feeling overwhelmed, stressed, and anxious during their undergraduate studies. Resilience refers to positive adaptation, or the ability to maintain or regain mental health, despite experiencing adversity (Herrman et al., 2011). While autonomic indices have been used to describe chronic physiological stress, the role of heart rate variability (HRV) as an index of resilience remains unclear. This research tested the hypotheses that (1) there is a relationship between HRV and resilience scoresand (2) a mentorship intervention will improve HRV and resilience outcomes. Fifty-seven first year students …

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 …

The Effect Of Anoxia On Mitochondrial Function In A Hibernator (Ictidomys Tridecemlineatus), Leah Hayward

Electronic Thesis and Dissertation Repository

Hibernation protects mammalian tissues against ischemia-reperfusion injury, but the underlying biochemical mechanisms are unknown. I hypothesized that the mechanisms allowing for mitochondrial metabolic flexibility during hibernation permit anoxia tolerance and contribute to tissue ischemia-reperfusion tolerance. I assessed mitochondrial performance before and after five minutes of anoxia in liver mitochondria isolated from thirteen-lined ground squirrels. I compared this anoxia effect among animals that were summer active (SA), or during hibernation (in torpor or interbout euthermia; IBE). Anoxia decreased state 3 respiration in all groups, but mitochondria isolated from torpid squirrels were least affected; these decreases paralleled decreased activity of electron transport …

Endothelial Glycocalyx Shedding In Pediatric Diabetic Ketoacidosis, Rufina Ning

Electronic Thesis and Dissertation Repository

Diabetic ketoacidosis (DKA) is a state of severe insulin deficiency resulting in hyperglycemia, ketoacidosis, and inflammation. Children with DKA have an increased risk of microvascular complications (e.g. stroke). The glycocalyx maintains the anti-thrombotic properties of endothelial cells (ECs), however the glycocalyx status is unknown in DKA. We quantified major glycocalyx components: hyaluronic acid (HA), heparan sulfate (HS), chondroitin sulfate (CS), and syndecan-1 in DKA plasma and correlated them with DKA severity. HA/HS were significantly increased in the plasma of DKA patients in comparison to insulin-controlled type-1 diabetics, but only HA correlated to DKA severity. Exogenous addition or removal of HA …

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 …

Mechanisms Underlying Freeze Tolerance In The Spring Field Cricket, Gryllus Veletis, Jantina Toxopeus

Electronic Thesis and Dissertation Repository

Freeze tolerance has evolved repeatedly across insects, facilitating survival in low temperature environments. Internal ice formation poses several challenges, but the mechanisms that mitigate these challenges in freeze-tolerant insects are not well understood. To better understand how insects survive freezing, I describe a novel laboratory model, the spring field cricket Gryllus veletis (Orthoptera: Gryllidae). Following acclimation to six weeks of decreasing temperature and photoperiod (mimicking autumn), G. veletis juveniles becomes moderately freeze-tolerant, surviving freezing at -8 °C for up to one week, and surviving temperatures as low as -12 °C. Acclimation is associated with increased control of the temperature and …

Pilot Study: Heart Rate Variability Analysis And Mental Health Outcomes In University Female Hockey Players, Kaitlyn Jacobs

Electronic Thesis and Dissertation Repository

Exercise improves anxiety and depression, both of which are associated with impaired autonomic regulation of heart rate (HR). In turn, HR variability (HRV) is a reliable physiological indicator of external stressors. The following research tested the hypothesis that HRV is indicative of chronic resilience towards mental stress in female varsity hockey players. Seventeen varsity hockey players (HOCK, age 21 ± 1.5) and fifteen healthy controls (CTRL, age 21 ± 2.2) at Western University participated three times throughout a 7-month season. Participants completed questionnaires (brief resilience scale, BRS; generalized anxiety scale, GAD-7; mental health inventory, MHI; visual analog scale, VAS; short …

Beta-Cell Β1 Integrin Deficiency During Second Transition Stage Of Fetal Pancreas Development On Islet Growth, Phyo Win

Electronic Thesis and Dissertation Repository

β1 integrin has been shown to be important for pancreatic beta-cell growth and functioning. Congenital and postnatal studies have shown beta-cell mass reduction with β1 integrin knockout (β1KO). Using an inducible cre recombinase (CreERT) expressed from the mouse insulin promoter (MIP) crossed to a line in which Itgb1 (β1 integrin encoding gene) was flanked by loxP sites (MIP-CreERT+; β1itg designated as MIPβ1KO), we examined the in vivo temporal role of beta-cell β1 integrin effect on islet growth during the second transition stage of pancreas development.

Prenatal MIPβ1KO mice displayed decreased beta-cell area, mass, density and proliferation. In addition, a decrease …

Heterotypic Docking Compatibility Of Human Connexin 37 With Other Vascular Connexins, Nicholas Kim

Electronic Thesis and Dissertation Repository

Gap junction (GJ) channels provide direct intercellular communication. A GJ channel consists of two docked hemichannels and each hemichannel is a hexamer of six connexins. Human vascular connexins (Cx37, Cx40, Cx43, and Cx45) can form various types of gap junction channels to synchronize vasodilation/constriction to control local circulation. Most of our knowledge on heterotypic GJs of these vascular connexins comes from studies on rodent connexins. However it is not clear if these human connexins can also form heterotypic GJs. The present study used an in vitro expression system to investigate the coupling status and GJ properties of human heterotypic Cx37/Cx40, …

Investigating The Role Of Pannexin 3 In Intervertebral Disc Health And Disease, Meaghan E. Serjeant

Electronic Thesis and Dissertation Repository

Pannexin 3 (Panx3) is a mechanosensitive, channel-forming glycoprotein implicated in the progression of post-traumatic osteoarthritis. Despite evidence for Panx3 expression in intervertebral discs (IVDs), its function here remained unknown. Using Panx3^-/- mice, this study investigated the role of Panx3 in age-associated and injury-induced models of IVD degeneration. While loss of Panx3 did not significantly impact the progression of age-associated IVD degeneration, it was associated with a protective phenotype in an injury model of IVD degeneration, specifically in the annulus fibrosus (AF). Following IVD injury, WT mice showed an accumulation of enlarged cells that appeared to contribute to disrupted AF …

Defective Aba-Mediated Sugar Signalling Pathway In An Established Arabidopsis Thaliana Cell Suspension Culture Explains Its Stay-Green Phenotype At High Sugar Concentrations, Avery Mccarthy

Electronic Thesis and Dissertation Repository

An unusual sugar insensitive phenotype was identified in an established cell suspension culture of Arabidopsis thaliana. We characterized the physiology, biochemistry and genetics of the sugar insensitive cell culture, in order to identify factors contributing to the phenotype. Chlorophyll levels of the cell suspension culture were insensitive to high sucrose (6-15% w/v) and maintained a green phenotype. Immunoblotting indicated that levels of key photosynthetic proteins (PsaA, Lhcb2 and Rubisco) increased as a function of external sucrose concentration. The green cell culture was photosynthetically competent based on light-dependent, CO₂-saturated rates of O₂ evolution as well as Fv/Fm …

Reactive Oxygen Species And The Regulation Of Cerebral Vascular Myogenic Tone, Neil Mazumdar

Electronic Thesis and Dissertation Repository

The myogenic response refers to the intrinsic ability of arteries to constrict to elevated pressure, developing “tone”. The underlying mechanism has yet to be elucidated but recent evidence suggests that the angiotensin II type 1 receptor (AT1R) is a key mechanosensor, linking intravascular pressure to tone development. One intriguing aspect of this receptor is its ability to activate NADPH oxidase (Nox), an enzyme responsible for the production of reactive oxygen species (ROS). The goal of this study was to ascertain the role of Nox in myogenic tone development. Isolated rat cerebral arteries were mounted in a myograph, pressurized to 60mmHg …

Functional Changes Associated With Shroom3 Deficiency And Mutation: Implications In Renal Pathophysiology And Disease, Doyun Ko

Electronic Thesis and Dissertation Repository

Chronic kidney disease (CKD) is a substantial global health burden that has recently been linked to the genetic locus SHROOM3 by several genome-wide association studies. Shroom3 is an actin-binding protein that is necessary for inducing apical constriction in epithelial cells. Our lab has previously shown that Shroom3 is critical for proper kidney development and loss of Shroom3 produces symptoms associated with CKD. As hypertension is both a leading cause and comorbidity of CKD, I hypothesized that loss of Shroom3 confers increased susceptibility to hypertension. Using a high-salt induced model of hypertension, I show that Shroom3 deficient mice do not become …