Life Sciences Commons^™

The Effects Of Resistance Exercise Training On Insulin Resistance Development In Female Rodents With Type 1 Diabetes, Mitchell James Sammut

Electronic Thesis and Dissertation Repository

The etiology of insulin resistance (IR) development in type 1 diabetes mellitus (T1DM) remains unclear; however, impaired skeletal muscle metabolism may play a role. While IR development has been established in male T1DM rodents, female rodents have yet to be examined in this context. Resistance exercise training (RT) has been shown to improve IR and is associated with a lower risk of hypoglycemia onset in T1DM compared to aerobic exercise. Additionally, the molecular mechanisms mediating RT-induced improvements in insulin sensitivity remain unclear. Therefore, the purpose of this study was to investigate the effects of RT on IR development in female …

Post-Activation Potentiation Induced By Concentric Contractions At Three Speeds In Humans, Alexander Zero

Electronic Thesis and Dissertation Repository

Post-activation potentiation (PAP) is the acute enhancement of contractile properties following a short duration (<10s) high intensity contraction. Compared with isometric contractions, little is known about the PAP response induced by concentric conditioning contractions (CCs) and the effect of contractile speeds. In the dorsiflexors of 10 participants, twitch responses were measured following 5s of maximal effort concentric CCs at each of 10, 20 and 50°/s. Concentric PAP responses were compared to a maximal isometric voluntary contraction (MVC) matched for contraction time. Additionally, concentric CCs were compared to isometric CCs matched for mean torque, contraction area and time. The principal finding was that the PAP response following maximal concentric CCs was independent of contractile speed and, there was no difference in the PAP response between concentric CCs and an isometric MVC. Maximal contractions, regardless of contraction modality, likely produce sufficient Ca²⁺ to induce a full PAP response, and thus there was no difference between speeds or contraction type. Concentric CCs had significantly larger peak twitch torque than their isometric torque matches (49-58%), and faster maximal rates of torque development at the three speeds (62-77%). However, these responses are likely related to greater muscle activation (EMG), and not contraction modality per se. Thus, PAP responses following maximal concentric CCs are not affected by velocity and responses are not different from an isometric MVC. This indicates maximal …

The Effects Of Exercise Training Versus Intensive Insulin Treatment On Skeletal Muscle Fibre Content In Type 1 Diabetes Mellitus Rodents, David P. Mcbey

Electronic Thesis and Dissertation Repository

In patients with Type I diabetes mellitus (T1DM) undergoing intensive insulin therapy, the development of insulin resistance (IR) is linked to the improper storage of intramyocellular lipid (IMCL) species. While both IR and IMCL are improved with combined aerobic and resistance training, it is unclear how these adaptations relate to individual fibre-type transitions and metabolic function. This study aimed to compare the effects of combined exercise training versus conventional and intensive insulin therapy on skeletal muscle fibres in T1DM rodents. Seventeen Sprague-Dawley rats were divided into groups: Control-Sedentary (CS; n=4), conventionally-treated T1DM sedentary (DCT; n=4), intensively-treated T1DM sedentary (DIT; n=5) …

Microvascular Stenosis In Critical Limb Ischemia: Role Of Partial Endothelial To Mesenchymal Transition, Jacqueline M. Chevalier

Electronic Thesis and Dissertation Repository

Critical limb ischemia (CLI) is a widespread and debilitating manifestation of atherosclerosis. Unfortunately, revascularization strategies are often precluded or unsuccessful, resulting in amputation. A major reason for treatment failure is likely co-existing abnormalities in ­­the microvasculature. However, the specific microvascular defects present in end-stage PAD in humans remain unknown.

The purpose of this study was to delineate abnormalities in the microvascular wall in the critically ischemic skeletal muscle of patients with CLI.

To elucidate the microvascular landscape in CLI, we studied human tibialis anterior and gastrocnemius muscles harvested from below-knee amputations of 10 individuals with CLI. Control muscles are from …

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. …

Comprehensive Topological, Geometric, And Hemodynamic Analysis Of The Rat Gluteus Maximus Arteriolar Networks, Mohammed K. Al Tarhuni

Electronic Thesis and Dissertation Repository

The objective of this thesis was to measure the geometric and topological properties of complete arteriolar networks within skeletal muscle, and to use these data as ideal inputs in a computational blood flow model in order to analyze the corresponding hemodynamic properties. Specifically, we sought to measure the levels of structural and hemodynamic heterogeneity exhibited within and between arteriolar networks. Intravital videomicroscopy was used to image and construct photomontages of complete arteriolar networks of the rat gluteus maximus muscle under baseline conditions. Arteriolar diameters, lengths, and inter-connections were analyzed and grouped according to a centrifugal ordering scheme. For all networks …

Novel Techniques For Investigating The Regulation Of Skeletal Muscle Hemodynamics, Baraa K. Al-Khazraji

Electronic Thesis and Dissertation Repository

The effect of the sympathetic nervous system (SNS) on blood flow distribution within skeletal muscle microvasculature is conditional upon regional activation of SNS receptors. Due to a lack of appropriate experimental models and techniques, no study has systematically evaluated the effect of SNS receptor activation in continuously branching skeletal muscle arteriolar trees. In line with previous work, we hypothesize that there will be a spatially-dependent distribution of sympathetic receptor activation along the arteriolar tree. Specifically, we anticipate a progressive decrease of adrenergic activation and a progressive increase of peptidergic and purinergic activation with increasing arteriolar order. We developed a novel …

Hypoxia-Induced Alterations In Skeletal Muscle Cell Respiration And Resveratrol As A Potential Pharmacological Intervention, Kathleen R. Belgrave

Electronic Thesis and Dissertation Repository

Using the C₂C₁₂ mouse muscle myoblast cell line, I sought to investigate the hypothesis that differentiation under hypoxia impairs muscle mitochondrial respiratory function irreversibly. Resveratrol (RSV) will increase expression of markers of mitochondrial biogenesis and reverse the hypoxia-induced depression of O₂ consumption rates. Hypoxia decreased oxygen consumption rates after five days of differentiation and after two days of normoxic recovery. This coincided with a hypoxia-induced decrease in protein levels of the NDUFB8 subunit of complex I of the electron transport chain and decreases in mRNA levels of mitochondrial biogenesis transcription factors, both of which could contribute …

Use Of Imaging Biomarkers To Assess Perfusion And Glucose Metabolism In The Skeletal Muscle Of Dystrophic Mice, Nabeel Ahmad, Ian Welch, Robert Grange, Jennifer Hadway, Savita Dhanvantari, David Hill, Ting-Yim Lee, Lisa M Hoffman

Robarts Imaging Publications

BACKGROUND: Duchenne muscular dystrophy (DMD) is a severe neuromuscular disease that affects 1 in 3500 boys. The disease is characterized by progressive muscle degeneration that results from mutations in or loss of the cytoskeletal protein, dystrophin, from the glycoprotein membrane complex, thus increasing the susceptibility of contractile muscle to injury. To date, disease progression is typically assessed using invasive techniques such as muscle biopsies, and while there are recent reports of the use of magnetic resonance, ultrasound and optical imaging technologies to address the issue of disease progression and monitoring therapeutic intervention in dystrophic mice, our study aims to validate …