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Articles 1 - 18 of 18
Full-Text Articles in Physiology
Regulation Of Liver Mitochondrial Metabolism During Hibernation By Post-Translational Modification, Katherine E. Mathers
Regulation Of Liver Mitochondrial Metabolism During Hibernation By Post-Translational Modification, Katherine E. Mathers
Electronic Thesis and Dissertation Repository
Hibernation, characterized by a seasonal reduction in metabolism and body temperature, allows animals to conserve energy when environmental conditions (e.g. temperature, food availability) are unfavourable. During hibernation, small mammals such as the 13-lined ground squirrel (Ictidomys tridecemlineatus) cycle between two distinct metabolic states: torpor, where metabolic rate is suppressed by >95% and body temperature falls to ~5 °C, and interbout euthermia (IBE), where metabolic rate and body temperature rapidly increase and are maintained at euthermic levels several hours. Suppression of metabolism during entrance into torpor is paralleled by rapid suppression of liver mitochondrial metabolism. In my thesis, I …
Power Reserve Following Ramp-Incremental Cycling To Exhaustion: Implications For Muscle Fatigue And Function, Michael D. Hodgson
Power Reserve Following Ramp-Incremental Cycling To Exhaustion: Implications For Muscle Fatigue And Function, Michael D. Hodgson
Electronic Thesis and Dissertation Repository
In ramp-incremental cycling exercise, some individuals are capable of producing power output (PO) in excess of that produced at their limit of tolerance (LoT) while others cannot. This study sought to describe the: 1) prevalence of a “power reserve” within a group of young men (n=21; mean ± SD: age 25±4 years; V̇O2max45±8 ml•kg-1•min-1); and 2) muscle fatigue characteristics of those with and without a power reserve. Power reserve was determined as the difference between peak PO achieved during a ramp-incremental test to exhaustion and maximal, single-leg isokinetic dynamometer power. Pre- versus post-exercise changes …
Ccn Proteins In Metastatic Melanoma, James Hutchenreuther
Ccn Proteins In Metastatic Melanoma, James Hutchenreuther
Electronic Thesis and Dissertation Repository
Melanoma cells recruit host tissue to become a part of the activated tumour stroma. This stromal microenvironment is similar to that seen in fibrotic tissue. CCN1 and CCN2 are tightly spatiotemporally regulated matricellular proteins involved in development and wound healing, and are abberantly expressed in fibrosis. Additionally they have been seen to be abnormally highly expressed in several cancers, including melanoma. Recent evidence has shown that deletion of CCN2 in the fibroblasts renders mice resistant to several models of fibrosis. Given this, I tested the hypothesis that deletion of CCN1 and CCN2 from fibroblasts could similarly impede the formation of …
The Effect Of Diet On Midgut And Resulting Changes In Infectiousness Of Acmnpv Baculovirus In Trichoplusia Ni, Elizabeth Chen
The Effect Of Diet On Midgut And Resulting Changes In Infectiousness Of Acmnpv Baculovirus In Trichoplusia Ni, Elizabeth Chen
Electronic Thesis and Dissertation Repository
The cabbage looper, Trichoplusia ni, a global generalist lepidopteran pest, has developed resistance to many synthetic and biological insecticides, requiring effective and environmentally acceptable alternatives. One possibility is the Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV). This baculovirus is highly infectious for T. ni, with potential as a biocontrol agent, however, its effectiveness is strongly influenced by dietary context. In this study, microscopy and transcriptomics were used to examine how the efficacy of this virus was affected when T. ni larvae were raised on different diets. Larvae raised on potato host plants had lower chitinase and chitin deacetylase transcript levels …
Distinct Roles Of Gaba(A)R Signaling In The Regulation Of Two Human T Lymphocyte Lines, Ying Lin
Distinct Roles Of Gaba(A)R Signaling In The Regulation Of Two Human T Lymphocyte Lines, Ying Lin
Electronic Thesis and Dissertation Repository
In response to antigen presentation, helper T lymphocytes (TH cells) initiate store-operated Ca2+ entry (SOCE) and differentiate into effector subtypes such as TH1 and TH2 cells. These cells play essential roles in adaptive immunity and the pathogenesis of various autoimmune and allergic diseases. The differentiation and activity of TH cells are also critically regulated by paracrine and autocrine soluble factors in the cell microenvironment. Previous studies have reported that TH cells produce gamma-aminobutyric acid (GABA) via glutamic acid decarboxylase (GAD) and express A-type GABA receptors (GABAARs), forming an autocrine GABA …
Hepatic Drug Metabolism, Uremic Toxins And Bacterial Composition Over Chronic Kidney Disease Progression, Emily Dee Hartjes
Hepatic Drug Metabolism, Uremic Toxins And Bacterial Composition Over Chronic Kidney Disease Progression, Emily Dee Hartjes
Electronic Thesis and Dissertation Repository
Uremic toxin retention and an altered gut microbiota are suspected to influence cytochrome P450s (CYPs) contributing to the unpredictable pharmacokinetics in chronic kidney disease (CKD). We aim to characterize dysbiosis and uremia to elucidate associations between CYP expression and CKD progression. Rats fed control or CKD-inducing diet were subsequently sacrificed across five time points over 42 days. CYP expression and activity were compared to alterations in the 1) plasma and liver metabolome and 2) bacterial microbiota. CYP3A2 and CYP2C11, respectively, were downregulated in CKD by ≥76% (p<0.001) simultaneously or slightly premature to CKD onset defined by creatinine. Metabolite profiles were altered before the gut microbiota and gut-derived uremic toxins including indoxyl sulfate, phenyl sulfate and 4-ethylphenyl sulfate correlated with CYP3A2 or CYP2C11. Identified bacterial genera, Turicibacter and Parabacteroides, characterized CKD and require future study. In conclusion, CYP3A2 and CYP2C11 are downregulated prior to dysbiosis but correlate with select uremic toxins.
The Effects Of Moderate Intensity Strength Training Coupled With Blood Flow Restriction: A 12 Week Intervention, Kelly Barrett
The Effects Of Moderate Intensity Strength Training Coupled With Blood Flow Restriction: A 12 Week Intervention, Kelly Barrett
Electronic Thesis and Dissertation Repository
Blood flow restriction training (BFRT) has been suggested to increase muscle size and strength in trained and untrained individuals when using light load intensities (30 percent 1-RM). However, there is little data to support its use when working with moderate load intensities, specifically, above 50 percent of an individual’s 1-RM. The purpose of this study was to evaluate the effects of moderate load intensity BFRT on muscle size and strength of the biceps brachii after a 12 week strength training intervention. Nine, previously strength trained, participants performed an elbow flexion exercise at 70 percent of their individualized 1-RM, twice per …
Functional Characteristics Of Four Novel Lone Atrial Fibrillation-Linked Connexin40 Mutants, Mahmoud Noureldin
Functional Characteristics Of Four Novel Lone Atrial Fibrillation-Linked Connexin40 Mutants, Mahmoud Noureldin
Electronic Thesis and Dissertation Repository
Atrial fibrillation (AF) is the most common form of cardiac arrhythmia. Recently, four novel heterozygous Cx40 mutations, K107R, L223M, Q236H, and I257L were identified in 4 of 310 unrelated AF patients. To study possible alterations associated with these mutants, we studied their localization and function using gap junction (GJ)-deficient model cells. Cell pairs expressing Q236H alone or together with wildtype Cx43 showed a significantly lower coupling conductance. Impaired GJ function and dominant negative action on Cx43 of this mutant are consistent with previous findings on the majority of AF-linked Cx40 mutants. The remaining three novel AF-linked mutants did not show …
The Role Of P62/Sqstm1 In Tgfβ-Dependent Emt And Autophagy, Evelyn Ng
The Role Of P62/Sqstm1 In Tgfβ-Dependent Emt And Autophagy, Evelyn Ng
Electronic Thesis and Dissertation Repository
Transforming growth factor beta (TGFβ) is a cytokine that regulates cellular adhesion, proliferation and apoptosis. In the context of cancer, TGFβ induces processes such as epithelial-to-mesenchymal transition (EMT). More recently, TGFβ has been discovered to also induce autophagy, and the relationship between TGFβ-induced EMT and autophagy remains unknown. Due to its involvement in autophagy and its established interactions with key TGFβ signaling proteins, this thesis focuses on the sequestosome 1 (p62/SQSTM1) protein. Here, I have shown that p62/SQSTM1 co-localizes with TGFβ receptors at the same time point that the receptors localize to Rab7-positive late endosomes. siRNA-mediated silencing of p62/SQSTM1 was …
Physiological Resolution Of Periodic Breath Holding During Heavy Intensity Fartlek Exercise, David J. Lim
Physiological Resolution Of Periodic Breath Holding During Heavy Intensity Fartlek Exercise, David J. Lim
Electronic Thesis and Dissertation Repository
The purpose was to compare the physiological responses to periodic 5 s breath holds (CBH), increased power output (FLK), and both (FBH) every 30 s followed by 25 s of continuous heavy intensity cycling exercise with free-breathing (CON). Minute ventilation (V̇ E) was greater (p < 0.05) in CBH (97.58 + 16 L·min-1) and FBH (100.9 + 19 L·min-1), pulmonary oxygen uptake (V̇ O2p) was similar in CBH (2.73 + 0.14 L·min-1) and FBH (2.73 + 0.14 L·min-1) and greater in FLK (2.85 + 0.12 L·min-1), compared to CON (2.71 + 0.12 L·min-1). FBH also resulted in slower V̇ O2p kinetics (62.2 + 19 s) and greater blood lactate concentrations (11.5 + 2.7 mM), compared to CON (48.8 + 12 s; 9.0 + 2.3 mM). Together, we demonstrated that breath hold-induced hypoxemia and hypercapnia were resolved when not combined with additional work.
S-Nitrosylation Suppresses Stromal Interaction Molecule-1 Activation And Ameliorates Cardiomyocyte Hypertrophy, Jinhui Zhu
Electronic Thesis and Dissertation Repository
Stromal interaction molecule 1 (STIM1) is an endo/sarcoplasmic reticulum (ER/SR) calcium (Ca2+) sensor that activates store-operated Ca2+ entry (SOCE) following Ca2+ depletion. SOCE-induced elevation of cytosolic Ca2+ stimulates the calcineurin/nuclear factor of activated T cells (NFAT) pathway, which upregulates pro-hypertrophic gene transcription. Nitric oxide (NO) regulates protein functions by S-nitrosylation, but how NO regulates SOCE in inhibiting cardiac hypertrophy is unclear. I hypothesize that NO stabilizes and inhibits STIM1 via S-nitrosylation and mitigates cardiomyocyte hypertrophy. STIM1 residues Cys49 and Cys56 were susceptible to S-nitrosylation by S-nitrosoglutathione (GSNO) and sodium nitroprusside (SNP), …
The Effect Of Insulin Treatment And Exercise Modality On Skeletal Muscle Fiber Size In Streptozotocin-Induced Type 1 Diabetic Rats, John Z. Nickels
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. …
Synaptic Mechanisms For The Hypothalamic-Pituitary-Adrenal Axis Activation By Prostaglandin E2, Zahra Khazaeipool
Synaptic Mechanisms For The Hypothalamic-Pituitary-Adrenal Axis Activation By Prostaglandin E2, Zahra Khazaeipool
Electronic Thesis and Dissertation Repository
The activation of the hypothalamic-pituitary-adrenal (HPA) axis during inflammation is mediated by prostaglandin E2 (PGE2) produced in the brain. However, how PGE2 recruits neuronal mechanisms for HPA axis activation remains unknown. Accumulating evidence indicates that GABA-mediated inhibitory synaptic transmission plays a major role in the HPA axis regulation. That is, GABAergic transmission constitutively constrains the excitability of parvocellular neuroendocrine cells (PNCs) in the paraventricular nucleus of the hypothalamus (the HPA axis output neurons); the removal from this inhibition (i.e. disinhibition) powerfully activates the HPA axis. My thesis examined the actions of PGE2 on GABAergic synaptic transmission to PNCs. Using patch …
Impaired Dynamic Cerebrovascular Autoregulation In Adolescent Concussion, Marcy Erin Moir
Impaired Dynamic Cerebrovascular Autoregulation In Adolescent Concussion, Marcy Erin Moir
Electronic Thesis and Dissertation Repository
Although cerebrovascular impairments are believed to contribute to concussion symptoms, little information exists regarding brain vasomotor control in adolescent concussion, particularly during changes in arterial blood pressure (ABP). This research tested the hypothesis that adolescent concussion is marked by impaired dynamic cerebral autoregulation (dCA). Thirty concussed adolescents and thirty healthy controls completed two sit-to-stand trials. Cerebral blood flow velocity and ABP were measured continuously. Cerebrovascular resistance (CVR) was calculated and the rate of drop in CVR relative to the change in ABP provided the rate of regulation (RoR). The concussed adolescents were followed through rehabilitation for up to 12-weeks. At …
Recruitment Strategies In Human Sympathetic Nerve Activity, Mark B. Badrov
Recruitment Strategies In Human Sympathetic Nerve Activity, Mark B. Badrov
Electronic Thesis and Dissertation Repository
The overall objectives of the current dissertation were to 1) establish the neural coding principles employed by the sympathetic nervous system (SNS) in response to acute physiological stress; and 2) to determine the various mechanisms of control underlying these sympathetic neural recruitment strategies. This research tested the working hypothesis that efferent post-ganglionic muscle sympathetic nerve activity exhibits neural coding patterns reflecting increased firing of lower-threshold axons, recruitment of latent sub-populations of higher-threshold axons, as well as malleable synaptic delays, and further, that these strategies are governed by factors such as reflex-specificity, stress severity, perception of effort or stress, age, and …
Mechanisms Underlying Variation In Insect Chill Tolerance: The Role Of Ion And Water Transport, Lauren E. Des Marteaux
Mechanisms Underlying Variation In Insect Chill Tolerance: The Role Of Ion And Water Transport, Lauren E. Des Marteaux
Electronic Thesis and Dissertation Repository
Water and ion homeostasis has emerged as an important factor limiting chill-susceptible insects at low temperatures; loss of this homeostasis in the cold likely contributes to chronic chilling injury, and reestablishment of homeostasis is required for recovery from chilling. Both plastic and interspecific variation in cold tolerance correlates with enhanced defense of water and ion homeostasis during cold exposure, however the mechanisms are poorly understood. Using Gryllus crickets, I generated and tested hypotheses about the mechanisms underlying this variation in transport function. I first related interspecific variation in cold tolerance to water and ion balance in early chill coma. A …
The Long Haul: Migratory Flight Preparation And Performance In Songbirds, Morag F. Dick
The Long Haul: Migratory Flight Preparation And Performance In Songbirds, Morag F. Dick
Electronic Thesis and Dissertation Repository
Migration requires birds to sustain high intensity endurance exercise for periods lasting from hours to days. Similar to athletes, preparation and nutrition is key to success. Birds seasonally prepare for migration, which includes increasing the capacity to oxidize fat in the flight muscles. Beyond fuelling migration, n-3 long-chain polyunsaturated fatty acids (PUFA) are hypothesized to be natural doping agents and increase endurance and fatty acid oxidative capacity. I examined how birds prepare for and sustain migratory flight and directly tested the role of n-3 PUFA. Using yellow-rumped warblers (Setophaga coronata) as a model species, I first examined the …
The Effects Of Sex, Energy, And Environmental Conditions On The Movement Ecology Of Migratory Bats, Kristin A. Jonasson
The Effects Of Sex, Energy, And Environmental Conditions On The Movement Ecology Of Migratory Bats, Kristin A. Jonasson
Electronic Thesis and Dissertation Repository
Lack of knowledge about the behaviour of migratory species during the migratory period is a major barrier to conservation efforts. In this thesis I focus primarily on differences between the sexes of the bat Lasionycteris noctivagans, during spring migration. Females are pregnant during spring migration and this overlap between migration and reproduction may affect the time and energy management of females as compared to males. In Chapter 2 I examine spring migration phenology of bats at a stopover site. Females arrived earlier than males, likely to give their pups a long growing season. Fat stores appeared to reflect a …