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

Receive updates for this collection

Vasoconstrictor responses assessed by near-infrared spectroscopy during graded lower body negative pressure

Author: 
Date created: 
2006
Abstract: 

Pathients with rthostatic intolerance have difficulty during the transition from supine to upright. Even healthy people may exhibit nausea, dizziness, or headache during long periods of standing. Lower body negative pressure (LBNP) is often used to simulate orthostatic stress to elucidate orthostatic reflexes. Near-infrared spectroscopy (NIRS) is used in various research and clinical fields. NIRS monitors tissue oxygenation changes by measuring oxygenated and deoxygenated hemoglobin (Hb) and it might be possible to apply NIRS to assess vascular responses during LBNP to blood volume change. The purpose of this thesis was to examine vasoconstrictor responses in the lower limbs during graded LBNP to determine the efficacy of using NIRS to investigate orthostatic mechanisms, and to investigate the physiological differences between subjects with high and low tolerance and between males and females during graded orthostatic stress. A series of five orthostatic studies were conducted: 1) Changes in (superficial) blood distribution in thigh during LBNP; 2) Assessments of tissue vascular responses between forearm and selective deep calf and calf with superficial portion during graded LBNP; 3) Comparisons of oxygenated Hb with blood flow measured by plethysmography and muscle sympathetic nerve activity during graded LBNP (reliability of calf blood flow assessment by selective deep oxygenated Hb); 4) Differential vasoconstrictor responses between subjects with low and high tolerance to graded LBNP; 5) Comparisons in peripheral vascular responses between genders (with high and low tolerant individuals) during graded LBNP. It was concluded that: 1) NIRS measurement of oxygenated and deoxygenated Hb was able to distinguish the tendency of blood distribution between the arterial and venous compartments during graded LBNP. 2) Selective deep calf oxygenated Hb responses assessed by a two-detector NIRS model may reflect (sympathetically mediated) blood flow changes in muscle vasculature. 3) Selective deep NIRS may be an useful tool to evaluate calf vasoconstrictor responses based on comparisons between selective deep oxygenated Hb responses (arbitrary units) and blood flow changes evaluated by mercury strain gauge plethysmography, and muscle sympathetic nerve activity assessed by microneurography. 4) The delayed reductions in the selective deep oxygenated Hb and heart rate (HR) increments in subjects with high compared to low tolerance may indicate that cardiovascular responses to LBNP in the High group were shifted toward more severe negative pressure levels during graded LBNP. 5) The greater reductions in oxygenated Hb with either negative pressure levels, or with blood pooling, in men compared to women suggest that men had greater vasoconstrictor responses during graded LBNP.

Document type: 
Thesis
File(s): 
Department: 
School of Kinesiology - Simon Fraser University
Thesis type: 
Dissertation (Ph.D.)

Multimodal contact cues for object manipulation in augmented and virtual environments

Date created: 
2007
Abstract: 

This thesis aims to increase our knowledge about the planning and organization of aiming and prehensile movements in augmented and virtual environments and to better understand how sensory information, such as vision, haptics and especially audition, is used for planning and control of simple movements. Five experiments were performed to investigate the importance of sensory contact cues when pointing and grasping augmented and virtual targets in computer-generated environments, with the hand and with a tool. Kinematic characteristics of transport and grasp movements as well as spatial error measures were examined. Experiment 1 explored the roles of natural haptic and computer-generated auditory contact information when grasping target objects of four different sizes. Results revealed the importance of contact information, and the benefit of auditory contact cues for improving reach to grasp performance in augmented and particularly in virtual environments. In Experiment 2 we introduced graphic contact cues, presented alone and in combination with auditory and haptic contact cues for a grasping task. We investigated the potential benefits and limitations of providing contact information in multiple sensory modalities. Overall, results were similar for auditory and auditory plus graphic conditions, while the graphic only condition mostly resembled the no cue condition. Experiment 3 extended the study of computer-generated auditory contact cues as redundant and substitutive for natural haptic information when grasping with a tool and found benefits of auditory cues on both kinematics and spatial error measures. Experiments 4 and 5 further investigated the effects of auditory and haptic contact cues on a pointing task, with the hand and with a tool. Both natural haptic and auditory contact cues had significant effects on kinematics and spatial error measures. Results are discussed in terms of implications for understanding multimodal information processing during manipulation, and for the design of multimodal displays in augmented and virtual environments.

Document type: 
Thesis
File(s): 
Department: 
School of Kinesiology - Simon Fraser University
Thesis type: 
Dissertation (Ph.D.)

Effect of exercise on retrograde transport in a mouse model of amyotrophic lateral sclerosis

Date created: 
2007
Abstract: 

The potential for exercise to improve function and delay disease progression in a mouse model of amyotrophic lateral sclerosis (ALS) has been examined in some detail. Recent studies have shown that retrograde transport is diminished throughout disease progression in this mouse model. The finding that exercise plus viral delivery of IGF-1 significantly improves lifespan of the G93A transgenic mouse highlights the need to investigate the mechanisms by which exercise may alter factors associated with the disease. Therefore, G93A and wild-type mice underwent an eight-week treadmill running protocol, and retrograde transport and neuromuscular junction integrity were examined. Retrograde transport was significantly improved (p<0.001) by exercise training in the transgenic animals. The percentage of innervated muscle fibers was also improved (p<0.01), and this improvement was highly correlated to the improvement in retrograde transport (r=0.75). These data indicate that exercise may enhance delivery of neurotrophic factors from skeletal muscle to motor neurons.

Document type: 
Thesis
File(s): 
Department: 
School of Kinesiology - Simon Fraser University
Thesis type: 
(Kinesiology) Thesis (M.Sc.)

Differential distribution of adipose tissue in South Asian and European populations

Author: 
Date created: 
2007
Abstract: 

The understanding of abdominal obesity is largely derived from studies on European Caucasians. South Asians show differences in body fat distribution. Visceral adipose tissue (VAT) accumulation is implicated as the primary concern of abdominal obesity. Objective: Determining the relationship between VAT and percent body fat between South Asian and European cohorts. Methods: A total of 212 South Asian and 201 European participants were assessed for VAT area, percent body fat, anthropometric measures, sociodemographics and physical activity. Results: Linear regression showed a significant ethnicity-body fat interaction in the fully adjusted model (p = 0.021). South Asians showed a significantly greater VAT at a given percent body fat than Europeans until 39.2% of body fat, at which Europeans exhibited a greater VAT for a given percent body fat than South Asians. Mean percent body fat for South Asians was 36.2%. Conclusion: These results indicate body fat distribution is influenced by ethnic background.

Document type: 
Thesis
File(s): 
Department: 
School of Kinesiology - Simon Fraser University
Thesis type: 
(Kinesiology) Thesis (M.Sc.)

Skeletal muscle regulatory factors with alterations in muscle mass

Date created: 
2007
Abstract: 

Given that maintenance of skeletal muscle mass is essential for overall health, functionality and quality of life, it is critical to elucidate the fundamental mechanisms underlying the maintenance of muscle mass which likely vary as a function of muscle status (i.e. healthy or diseased). This thesis examined key skeletal muscle regulatory factors (smRF’s) that are known to affect skeletal muscle mass, including components of the PI3K/Akt and MAPK(ERK) pathways, calcineurin, the myogenic regulatory factors and myostatin, following administration of a b2-adrenergic agonist, Clenbuterol, and with progressive denervation. Although it is known that Clenbuterol induces hypertrophy and attenuates atrophy of skeletal muscle, its mechanism of action is unclear. In this thesis, I have demonstrated that Clenbuterol induces PKA-independent stimulation of smRF’s (cAMP, p-Akt, p-ERK), and additional phospho-kinases (PKCa, PAK1/2/3, FAK and Pyk2) that are also thought to be involved in regulating muscle mass. These changes occur relatively rapidly, often within 10 minutes of administration. Using a G93A mouse model of progressive denervation, I found an up-regulation of smRF’s involved in growth/survival (Akt, calcineurin, ERK1/2), and decreases in the myogenic regulatory factor, MyoD, in skeletal muscle of these mice. These alterations occurred in conjunction with the onset of later-stage (i.e. severe) symptoms but prior to significant muscle atrophy. I was therefore interested in determining if Clenbuterol would attenuate the onset of disease symptoms and muscle atrophy accompanying the progressive denervation by altering these smRFs. Akt and MyoD levels in the G93A mouse were similar to wild-type muscle after six weeks of Clenbuterol treatment. Clenbuterol also attenuated the progression of symptoms in G93A mice which may account for the levels of smRF’s observed. Increases in G93A mouse body mass, improved motor coordination (RotoRod) and strength (PaGE, females only) were also observed with Clenbuterol treatment without significant increases in muscle mass. This thesis suggests that alterations in smRF’s, including the PI3K/Akt and MAPK(ERK) pathways, calcineurin, and the myogenic regulatory factors occur prior to any observable changes in muscle mass. Identification of these muscle-specific factors has clinical relevance for the characterization and treatment of skeletal muscle atrophy associated with chronic diseases.

Document type: 
Thesis
File(s): 
Department: 
School of Kinesiology - Simon Fraser University
Thesis type: 
Dissertation (Ph.D.)

The Effects of Hypoxia and Core Temperature on Ventilation During Low Intensity Exercise

Author: 
Date created: 
2004
Abstract: 

The independent and combined effects of hypoxia and elevated esophageal temperature (T,,) were investigated for their effects on the level and lunetics of exercise ventilation (VE). In either a 'hyperthermic' T,, or a 'normothermic' Tes session, 11 college-aged, healthy males were immersed to the shoulders and pedalled on an underwater cycle ergometer at a steady-state oxygen consumption (V02) of 0.87 ~.min-' (SD 0.07). Following a 30-min rest and 20-min warm-up, a 30-min steady-state cycling period was divided into three 10 min gas phases when participants inhaled: air (Euoxia 1 (El)), hypoxic gas (12 % 0 2 and 88 % N2 (HI)), and air (Euoxia 2 (E2)). End-tidal C02 (PETC02) was maintained at an isocapnic level of 5.19 kPa (SD 0.71) throughout the exercise. Venous blood samples were drawn at rest and 5 min into all gas phases. Results showed a significant increase in \jE during all hyperthermia conditions (0.0kP c 0.048), however, during hyperthermic hypoxia there was a disproportionate and significant (P = 0.017) increase in VE relative to normothermic hypoxia. This was the main explanation for a significant core temperature and gas type interaction (P = 0.012) for VE. A main effect of core temperature (P = 0.007) was evident on ventilation frequency (f,) with an increased rate of breathing in hyperthennic relative to the normothermic exercise. This gave evidence of a thermally-induced tachypnea which corresponded to significant decreases in inspiratory time (TI) (P = 0.035) and expiratory time (P = 0.014) and was independent of any changes in tidal volume (VT) (P = 0.801). As such inspiratory flow ( v T . ~ f l ) was significantly increased in hyperthermic- relative to normothermic (P = 0.003) exercise, an increase that was pronounced (P = 0.013) during hyperthermic hypoxia. A significant reduction of the time constants (z) for vE was evident (P = 0.032) during the onset of exercise under the hyperthermic as compared to the normothermic condition. This reduction in z was associated with an increase in T,, (R' =0.829, P = 0.01 1) but not in skin temperature. Between core temperature levels there were no significant changes in z for the VE response from euoxic to hypoxic steady-state exercise. From normothermic to hyperthermic exercise increases of VE in El were 9.4 % (SD 9.7) and not significantly different than the 6.9 % (SD 10.7) increase in V02. However in HI, vE and V O ~ increased by 29.2 % (SD 25.5) and 13.5 % (SD 10. I), respectively, which bordered a significant difference (P = 0.056). No changes in lactate or potassium (K') levels were evident across all gas type and core temperature conditions. In conclusion, these results suggest the following: 1) During low intensity, steady-state exercise an elevated Tes caused an increased vE, which was mediated by an increased f,. 2) The addition of hypoxia during hyperthermic exercise caused a multiplicative increase in VE which corresponded with a multiplicative increase in V~.T~-'. This would suggest the possibility of a core temperature mediated stimulation of the peripheral chemoreceptors. 3) An increased Tes during the onset of exercise but not during the transition from low intensity euoxic to hypoxic exercise shortened the time course of the VE response. 4) Oxygen consumption, K+ and lactate did not appear to be significant mediators of the augmented hyperthermic hypoxic VE response. Overall the results support the hypothesis that temperature plays a significant role in the control of ventilation, particularly during hypoxic exercise.

Document type: 
Thesis
File(s): 
Department: 
School of Kinesiology - Simon Fraser University
Thesis type: 
(Kinesiology) Thesis (M.Sc.)

Utilization of the world wide web to deliver cardiac rehabilitation at a distance

Author: 
Date created: 
2006
Abstract: 

Cardiovascular disease (CVD) is a growing epidemic and economic burden in Canada and North America. Cardiac Rehabilitation Programs (CRP) have been proven to reduce CVD risk, decrease health care cost and decrease mortality by 25%. With current waitlists of 2 to 5 months and the inaccessibility of CRP to suburban and rural patients, conducting cardiac rehabilitation through the Internet will decrease barriers related to distance and service delivery and allow patients from around the province to interact with cardiac rehabilitation specialists, essentially bridging the treatment gap. The virtual cardiac rehabilitation program (vCRP) was a randomized controlled trial (n=15) investigating a 12-week web-based CRP. Outcome investigated were changes in exercise capacity, physical activity participation, lipid profiles, diet composition and level of self-efficacy. Significant findings within the intervention group included the lipid values for HDL-C (p. <0.025), TG (p. < 0.012), TCIHDL-C ratio (p. < 0.012), self- efficacy (p. ~0.018) and physical activity participation (p. < 0.01 8). There was also a clinically significant finding with an increase in exercise capacity. Other reported outcomes from patient interviews indicate overall satisfaction with the program and noted positive behaviour change.

Document type: 
Thesis
File(s): 
Department: 
School of Kinesiology - Simon Fraser University
Thesis type: 
(Kinesiology) Thesis (M.Sc.)

The human factors of integrating technology into the mine countermeasures diving environment

Author: 
Date created: 
2006
Abstract: 

A series of experiments were conducted to determine the manual performance, information processing, visual and perceptual capabilities of divers in simulated operational environments. Results were combined to develop comprehensive ergonomic guidelines for underwater equipment and displays. These guidelines were used to optimize the display of information and to evaluate three different underwater displays for mine countermeasures (MCM) divers. Experiments were designed to quantify the manual performance capabilities of divers, and the deficiencies caused by wearing neoprene gloves, exposure to cold (4 'c), narcosis, and pressure (40 msw). Results showed a 5 60% decrement in tactile sensitivity and manual dexterity when wearing gloves in cold water (p

Document type: 
Thesis
File(s): 
Department: 
School of Kinesiology - Simon Fraser University
Thesis type: 
Dissertation (Ph.D.)

Muscle-associated Drosophila adducin regulates larval neuromuscular junction development and the localization of Draper to the synapse

Author: 
Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2013-01-28
Abstract: 

Adducin, the cross linker of actin and spectrin, has important regulatory roles in the remodeling of submembranous cytoskeleton during synaptic development. In Drosophila, Drosophila adducins, encoded by hu-li tai shao (hts), are localized to both pre-synaptic and post-synaptic larval neuromuscular junction (NMJ). In animals with muscle-specific knock-down of Hts, NMJs are underdeveloped, whereas overexpression of Hts in the muscle results in NMJ overgrowth. Draper, a transmembrane engulfment receptor, has also been shown to regulate larval NMJ development and may interact with Hts. In vivo, Draper colocalizes with Hts at the postsynaptic region. Moreover, in animals with muscle-specific knock-down of Hts, Draper is more tightly localized to the synapse, whereas overexpression of Hts causes delocalization of Draper immunoreactivity from the synapse. This delocalization of Draper induced by Hts highlights a new avenue by which Hts may be exerting its influence on NMJ development.

Document type: 
Thesis
File(s): 
Supplemental video
Supplemental video
Supervisor(s): 
Wade Parkhouse
Department: 
Science: Department of Biomedical Physiology and Kinesiology
Thesis type: 
(Thesis) M.Sc.