Physiology Commons^™

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 …

Cardioprotective Role Of The Cholinergic System, Mouhamed Dakroub

Electronic Thesis and Dissertation Repository

The process of aging is an irreversible continuum experienced by all individuals. A large number of physiological transformations occur to the cardiovascular system as one ages. These changes result in increased risk of developing cardiovascular diseases, many of which are frequently seen in geriatric populations. While the exact mechanisms of age-related cardiac dysfunction have not been established, abnormal cholinergic dysfunction has been implicated in the pathology of other age related diseases; therefore, we have hypothesized that age induced cholinergic dysfunction is detrimental to cardiac function and health. This study seeks to identify whether increased cholinergic signaling, either by transgenic overexpression …

Quantifying The Effect Of Age And Contraction Mode On The Force-Velocity-Power Relationship In The Knee Extensors, Justin R. Paturel

Electronic Thesis and Dissertation Repository

PURPOSE: To assess and compare the force-velocity-power relationship (F-V-P) using isotonic and isokinetic knee extensions in 11 younger (19-30y) and 11 older (69-81y) men. METHODS: The construction of the F-V-P curves were attained with each participant performing maximal, explosive knee extensions at 8 different loads (isotonic) and 8 different velocities (isokinetic) on a Cybex HUMAC NORM dynamometer. Maximal voluntary contraction (MVC or P_o), maximal shortening velocity (V_max), maximum power, optimal torque (P_opt) and velocity (V_opt) were assessed and compared. RESULTS: The older men were 43% weaker, 18% slower and ~54% less powerful …

Aging And Obesity Models In Osteoarthritis, Sara Ohora

Electronic Thesis and Dissertation Repository

Osteoarthritis (OA) is a degenerative joint disease whose exact mechanisms are not well understood, but aging and obesity are common risk factors. To determine the role of transforming growth factor-alpha (TGFα) in obesity-associated OA, Tgfa null and control mice on control and high fat diets were compared. In addition, spontaneous OA was investigated in aging C57BL/6J mice. Quantitative magnetic resonance was used to assess body composition in the obesity model, while gait analysis, histological staining and OARSI scoring were used to determine OA in both models. Mice on high fat diet developed no OA, but Tgfa null mice weighed significantly …

Neuromuscular Function Following Lengthening Contractions, Geoffrey A. Power

Electronic Thesis and Dissertation Repository

Unaccustomed lengthening contractions have been shown to impair muscle function - however little is known regarding this impairment on muscle power - specifically, the velocity component of power during voluntary contractions in humans. The four studies presented in my thesis investigated power-loss following lengthening contractions in healthy young and old women and young men.

The purpose of Study 1 was to determine reliability of velocity-dependent power of the dorsiflexors using the isotonic mode of the Biodex Dynamometer. I determined the isotonic mode is reliable and can be used to track changes in velocity and power following fatigue and lengthening contractions. …

Neuroprotective Effects Of Long-Term Endurance Training On The Cortical Autonomic Network In The Aging Brain, Torri A. Luchyshyn

Electronic Thesis and Dissertation Repository

This study tested whether long-term endurance training in older adults (ET; n = 15, 55 ± 4 years, relative VO₂max = 50 ± 8 ml/kg/min) would alter cardiovagal control and preserve the cortical autonomic network compared to age-matched controls (CON; n = 15, 56 ± 4 years, relative VO₂max = 37 ± 9 ml/kg/min). The hypothesis predicts 1) altered deactivation patterns of the ventral medial prefrontal cortex (vMPFC) in response to isometric hand grip (IHG) and 2) greater indices of cardiovagal control; a) increased baroreflex sensitivity at rest, b) greater heart rate change (ΔHR) and c) …