Biomedical Physiology and Kinesiology - Theses, Dissertations, and other Required Graduate Degree Essays

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An examination of how physical activity and sedentary behaviour in older adults in Assisted Living associate with physical, cognitive and psychosocial function

Author: 
Date created: 
2011-04-29
Abstract: 

Physical activity and sedentary behaviour are important markers of health and quality of life, and predictors of functional decline. However, the factors that influence movement patterns in older adults, especially for those residing in the growing assisted living (AL) setting, are poorly understood. I acquired measures from 114 AL tenants of movement patterns from waist-mounted accelerometers worn for at least 3 days. On average, participants spent 86% of their waking hours in sedentary behaviour and 13.84% in light physical activity. The time spent sedentary was higher in males than females, and correlated with scores on the Timed-Up-and-Go and Modified Fall Efficacy Scale, but not with the Montreal Cognitive Assessment or Geriatric Depression Scale. These results indicate that both physical function and psychological factors influence sedentary behaviour in AL tenants. Future research should examine whether interventions targeted at intrinsic or environmental factors decrease sedentary behaviours.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Stephen Robinovitch
Department: 
Science: Department of Biomedical Physiology and Kinesiology
Thesis type: 
(Thesis) M.Sc.

C121W: A thermosensitive sodium channel mutation

Author: 
Date created: 
2011-06-16
Abstract: 

A mutation in the β1 subunit of the voltage-gated sodium (NaV) channel, β1(CW), causes genetic epilepsy with febrile seizures plus (GEFS+), wherein elevated body temperature increases neuronal excitability. This study investigated the putative mechanism underlying seizure generation in β1(CW) caused by elevated temperature. Whole-cell voltage clamp experiments were performed on CHO cells expressing the α subunit of neuronal isoform NaV1.2, either alone, with β1, or with β1(CW) at 22°C and 34°C . Results suggest that wild-type β1 is protective against increased channel excitability induced by elevated temperature, and that this protection is lost in the absence of β1 or with the expression of β1(CW). At 34°C, β1(CW) increased channel excitability compared to wild-type β1 by decreasing use-dependent inactivation, increasing persistent current and window current, and delaying the onset of, and accelerating the recovery from, fast-inactivation. These results help explain how the β1(CW) mutation contributes to the febrile seizure phenotype by increasing channel excitability specifically at elevated temperature.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Peter Ruben
Department: 
Science: Department of Biomedical Physiology and Kinesiology
Thesis type: 
(Thesis) M.Sc.

Muscular & mechanical efficiency in cycling

Date created: 
2011-06-14
Abstract: 

In cycling some muscle coordination patterns result in high power outputs whereas others are more efficient. This study examined mechanical factors that affect muscle activity to identify coordination patterns used for different power outputs, total muscle activation and muscle activation effectiveness to produce power in cycling. Electromyography, pedal forces, kinematics, power output, cadence and slope were measured and compared indoors and/or outdoors in competitive cyclists at a range of resistances indoors and natural resistances during a time-trial outdoors. A trade-off existed between high power and high overall mechanical efficiency. Increased efficiency was dependent on the coordination of all muscles and independent of pedal force direction, while high power resulted from elevated activity of only a few muscles. Muscle coordination was influenced by workload and slope through altered power output or cadence. The study highlights the importance of specificity in cycling training to maximize exposure to competition specific muscle coordination patterns.

Document type: 
Thesis
File(s): 
Supervisor(s): 
James Wakeling
Department: 
Science: Department of Biomedical Physiology and Kinesiology
Thesis type: 
(Thesis) M.Sc.

Molecular mechanisms underlying gating and pHo modulation of the hERG cardiac K+ channel

Date created: 
2011-05-31
Abstract: 

hERG encodes a K+ channel that underlies the repolarizing cardiac current IKr. Inherited mutations and/or acidosis, as with myocardial ischemia, disrupt hERG gating and lead to life-threatening arrhythmias. Therefore, understanding the mechanisms that underscore hERG gating and proton modification is crucial. Here, we identify a unique glycine (G546) as being critically involved in the unusually slow gating of hERG channels. We show that G546 provides flexibility to the S4-S5 linker, stabilizing the closed state of WT hERG channels. Also, we demonstrate that low pHo inhibits hERG channel function by two independent mechanisms that are not mediated by native histidines: 1) an acceleration of channel closure due to acceleration of voltage sensor return; 2) a reduction of maximal conductance due to direct block of the pore. These data provide novel insight into the mechanisms underlying hERG’s slow gating and reveal the molecular basis underlying proton modulation as seen with myocardial ischemia.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Thomas Claydon
Department: 
Science: Department of Biomedical Physiology and Kinesiology
Thesis type: 
(Thesis) M.Sc.

‘Dealing’ with complexity: construction and analysis of a card based communication tool for patients with obesity

Date created: 
2011-05-24
Abstract: 

Clinical communication tools have been used as aids in the treatment of diseases such as diabetes and cancer but not obesity. The objective of this project was to create and test a card based communication tool for use between patients with obesity and health care practitioners. A total of 64 cards were developed based on summaries of the complex set of factors associated with obesity and various survey tools. Subjects participated in either semi-structured interviews or a focus group where they sorted through the deck and selected statements they identified with, followed by a recorded discussion of the activity. Age was negatively associated with the number of cards selected. Qualitative analysis revealed several patterns in participant preference for using the tool (e.g. communication with a healthcare practitioner or monitoring progress). These results will aid in refining the tool and provide some practical information to healthcare practitioners on communication around obesity.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Dr. Diane Finegood
Dr. Scott Lear, Dr. Mary Forhan
Department: 
Science: Department of Biomedical Physiology and Kinesiology
Thesis type: 
(Thesis) M.Sc.

Physiological mechanisms of nutrient transport: calciferols and vitamin D-binding protein

Author: 
Date created: 
2011-04-19
Abstract: 

Biologically active metabolites of vitamin D affect cell growth and differentiation, and thereby contribute to physiological regulation. Vitamin D-binding protein (DBP) binds 25-hydroxycholecalciferol and other D metabolites, and participates in their delivery to cells. Based on evidence for receptor-mediated endocytosis (RME) of DBP, experiments were performed to analyze DBP transport in animal tissues and cells. The results provide evidence that DBP RME can occur through a pathway that differs from the well-characterized clathrin-dependent endocytic pathway of transferrin (Tf, circulatory iron carrier protein). Moreover, cell growth density has differential effects on (a) the endocytosis of Tf and DBP, and (b) epidermal growth factor-mediated stimulation of DBP endocytosis. Comparative analyses of tissues and cells provides evidence for possible hormonal (e.g., estradiol) and aging effects on transport and receptor-binding parameters of DBP and other nutrient carrier proteins.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Amandio Vieira
Department: 
Science: Department of Biomedical Physiology and Kinesiology
Thesis type: 
(Thesis) M.Sc.

Molecular and cellular studies of transthyretin and related amyloid pathogenesis

Author: 
Date created: 
2011-03-31
Abstract: 

Transthyretin (TTR) is a tetrameric protein involved in the extracellular transport of various compounds including thyroid hormones and retinol (vitamin A). Misfolded and aggregated TTRs (agTTR) contribute to amyloidogenic diseases such as senile systemic amyloidosis and familial amyloid polyneuropathy which are characterized by extracellular deposition of transthyretin-containing amyloid fibrils. The main objective of this thesis project was to examine the cellular toxicity of agTTR as it relates to amyloidogenic disease. Novel evidence is provided—through multiple biochemical and cellular experimental strategies—for disruption of cell membrane structure and function, and induction of oxidative stress, by agTTR relative to normal TTR or non-TTR controls. Cells treated with agTTR had a decreased capacity to bind filipin and were deficient in receptor-mediated endocytosis of the circulatory iron-carrier protein, transferrin (Tf). Increased levels of pro-oxidative species including hydrogen peroxide and nitrite, and lower levels of antioxidant factor such as glutathione and catalase, were detected upon agTTR treatement of different human cell lines. Cytosolic fractions of cells treated with agTTR exhibited decreased total antioxidant potential; and such a decrease could be moderated by redox modulators such as apocynin and NG-monomethyl-L-arginine. Hypotheses were also proposed and tested in relation to more basic physiological studies of TTR cellular receptors and endocytic transport. Biochemical evidence is provided for a TTR endocytic pathway that is different from the well-established clathrin-mediated endocytosis of Tf, and likely represents a caveolar endocytic pathway. Moreover, through chemical crossslinking and ligand blotting experiments, evidence was obtained for a novel somatic cell membrane TTR receptor.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Dr. Amandio Vieira
Department: 
Science: Department of Biomedical Physiology and Kinesiology
Thesis type: 
(Dissertation) Ph.D.

Influence of body temperatures and hypercapnia on pulmonary ventilation during hyperthermia

Date created: 
2010-06-22
Abstract: 

Static and dynamic body temperatures, hypercapnia, and exercise state were assessed for their influence on human pulmonary ventilation. METHODS: In study 1, each participant exercised with normothermic and hyperthermic core temperatures, in ambient temperatures of 25, 30 and 35°C, and were subjected to hypercapnic challenges of +4 and +8 mmHg in each condition. In study 2 before and after sub-maximal exercise, radiant heating was employed to assess the influence of dynamic skin temperature on ventilation. RESULTS: In study 1, during hyperthermia there was a significant effect of mean skin temperature (F=4.1;p<0.04) on exercise ventilation. Mean skin temperature did not interact with hypercapnia in its influence on exercise ventilation. In study 2, there was a significant effect of rate of skin temperature change (F=28.8;p<0.01) on resting ventilation. Conclusion: Evidence supports static mean skin temperature during exercise and dynamic skin temperature at rest each contribute to control of pulmonary ventilation.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Matthew White
Department: 
Science: Department of Biomedical Physiology and Kinesiology
Thesis type: 
(Thesis) M.Sc.

Biomechanics of postural stability when accepting a weight in the outstretched hands

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2004
Document type: 
Thesis
File(s): 
Supervisor(s): 
John Dickinson
Department: 
Science: Department of Biomedical Physiology and Kinesiology
Thesis type: 
(Thesis) M.Sc.

Prediction of autoimmune diabetes in the non-obese diabetic mouse by ex vivo analysis of autoreactive cytotoxic T lymphocytes

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2003
Document type: 
Thesis
File(s): 
Supervisor(s): 
Diane Finegood
Department: 
Science: Department of Biomedical Physiology and Kinesiology
Thesis type: 
(Dissertation) Ph.D.