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

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Mechanisms of postoperative junctional ectopic tachycardia: Chronotropic and inotropic regulation in the neonate heart

Date created: 
2005
Abstract: 

Junctional ectopic tachycardia (JET) is a common arrhythmia in postoperative pediatric patients after open-heart surgery for congenital heart defects. This arrhythmia is life-threatening and mechanisms of this arrhythmia are not yet clear. Isolated working hearts from neonate rabbits were administered P-adrenergic agonists alone or with antagonists under normal or ischemia-reperfusion stunned conditions. The effect of the sodium hydrogen exchanger inhibitor HOE642 on the recovery of ischemia-reperfusion stunned leA ventricle was tested, the potential for P-adrenergic agonist-induced arrhythmogenesis on the stunned neonate hearts was examined as well. We found that dopamine has a positive chronotropic, and a negative inotropic effect on the isolated neonate rabbit heart. Furthermore, dopamine has an arrhythmogenic effect on the ischemia-reperfusion stunned neonate myocardium. Finally, it was shown that HOE642 has a significant protective effect on contractile function in the neonate myocardium on recovery from ischemia-reperfusion stunning, but was not robust in its antiarrhythmic effect.

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

Improving the detection and triage of oral premalignant lesions in high-Risk clinics and community dental practices

Author: 
Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2009
Abstract: 

Oral cancer occurs at a cancer site that is easily examined; yet more than 40% of oral cancers are diagnosed at a late stage when the chance of death is high and treatment can be devastating. Although oral cancer screening is part of every oral health professional’s (OHP) training, it is often difficult for OHPs to differentiate high-risk oral premalignant lesions (OPLs) from benign reactive lesions. A primary goal of this thesis was to evaluate two approaches to enhancing visualization of clinical lesions: the application of toluidine blue (TB) stain, used to improve contrast of suspicious mucosal areas in normal tissue (Project 1), and fluorescence visualization (FV), used to identify an alteration to tissue optics that is associated with morphological and biochemical change seen in cancers and premalignant disease (Projects 2 and 4). A second goal was to develop and evaluate an educational strategy for oral cancer screening in community dental clinics aimed at strengthening conventional screening activities and providing a framework for integration and assessment of visualization techniques in community settings (Projects 3 and 4). Studies were conducted on patients within two settings: referral clinics of the BC Oral Cancer Prevention Program (Projects 1 and 2) and community dental clinics in the Vancouver lower mainland (Projects 3 and 4). Use of two settings is important: technology developed within high-risk referral settings needs to be re-evaluated in community clinics where the spectrum of disease is different and expertise is variable. Among key results of these studies were: a strong association between TB positive staining and increased (6-fold) cancer risk for OPLs; an association of FV and high-risk clinical, histological and molecular change; and; identification of barriers and facilitators for oral cancer screening in OHPs with evaluation of a triaging framework to support key decision points in community practices. In summary this thesis data supports the use of TB and FV visualization approaches in high-risk clinics to improve detection of OPLs. In addition, the community studies have produced a framework for transfer of new technology into general dental practice building upon an enhanced triage and referral system.

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

Upper trapezius recruitment with a repetitive upper limb task: comparison of female WADII subgroups and healthy controls

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2009
Abstract: 

Persistent neck pain in whiplash associated disorders (WAD) is a worldwide problem. In an effort to improve classification and management of people with WADII, surface EMG of upper trapezius of the dominant limb was compared between 10 healthy women and 19 women with persistent neck pain post motor vehicle accident, before, during, and after a repetitive upper limb task. Separate analyses were also performed with the WADII women grouped by level of disability (Neck Disability Index scores) as well as using a clinically focused system, the Sterling Classification System (WADIIA, WADIIB, WADIIC). Evidence of abnormalities of upper trapezius recruitment were present in the women with persistent neck pain and WADII, however, further research is indicated to understand the clinical implications of these changes and optimal intervention strategies.

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

Adaptive Tetrodotoxin-Resistance in Garter Snake Sodium Channels

Author: 
Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2009
Abstract: 

Tetrodotoxin (TTX) is a neurotoxin that specifically binds to voltage gated sodium channels (NaV). TTX binding physically blocks the flow of sodium ions through NaV, thereby preventing action potential generation and propagation. TTX has different binding affinities for different NaV isoforms. These differences are imparted by amino acid substitutions in positions within, or proximal to, the TTX binding site in the channel pore. The garter snake Thamnophis sirtalis has evolved TTX-resistance over the course of an arms race, allowing some populations of snakes to feed on tetrodotoxic newts, including Taricha granulosa. We tested the properties of NaV with TTX resistance found in garter snake populations. We observed some surprising changes in gating properties and ion selectivity of the TTX resistant NaV. These results suggest TTX resistance comes at a cost to performance caused by changes in the biophysical properties and/or ion selectivity of the TTX resistant

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

Mechanics and energetics of step-to-step transitions

Date created: 
2009
Abstract: 

The major determinant of walking’s metabolic cost is the work required to redirect the centre of mass velocity during step-to-step transitions. My first aim was to isolate transitions from other contributors to walking mechanics. The results demonstrated that sagittal plane rocking reproduced the important characteristics of walking’s transitions including a strong dependence of work on step length and a proportional increase in metabolic cost. My second aim was to use rocking to gain insight into pathological gait’s elevated cost. Physics-based mathematical models predict sub-optimal transitions occur when one or both legs are unable to generate mechanical power with the optimal timing and magnitude, requiring a greater magnitude of total work and an increase in metabolic cost. I tested this prediction by immobilising the ankle joints of healthy subjects to simulate sub-optimal transitions and found that joint immobilization indeed caused sub-optimal transitions thereby increasing transition work and metabolic cost.

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

Changes in patterns of EMG activity in post-stroke subjects following robot-assisted hand rehabilitation.

Author: 
Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2009
Abstract: 

A feasibility study of robot-assisted hand rehabilitation post-stroke was conducted to investigate changes in activation patterns of forearm and hand muscles. Four stroke survivors received robot-assisted hand rehabilitation twice a week for two months. Eight healthy age-matched control subjects performed the same exercises as stroke subjects in a single training session. The pattern of activation of forearm and hand muscles was analyzed by performing Principal Component Analysis on the root-mean-square electromyogram. No differences were found in the number of principal components required to account for 95% of the variance between stroke and healthy subjects or pre- and post-rehab even though the majority of subjects used different muscle activation patterns for different exercises and changed their activation patterns from pre- to post-rehab. Stroke subjects were found to have more co-contraction of antagonistic muscles than healthy subjects pre-rehab. In most cases, the amount of co-contraction did not decrease from pre- to post-rehab.

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

Src homology 2 domain-containing inositol-5’ phosphatase in a murine model of Amyotrophic Lateral Sclerosis

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2009
Abstract: 

As Src homology-2 domain-containing inositol-5’ phosphatase (SHIP-1) expression has been implicated in inflammation, immunoreactivity against SHIP-1 was evaluated in mice over-expressing mutant superoxide dismutase (mSOD-1) and wild-type (wt) mice. Spinal cord sections were examined at 11 weeks, 15 weeks of age and at end-stage. SHIP-1 immunoreactivity was detected in mSOD-1 mice at end-stage when considerable motor disability is evident, and at 15 weeks, but not in wt mice. At 15 weeks, SHIP-1 was prominent in the ventral horn, and by end-stage, immunoreactivity was detected throughout the ventral and dorsal regions. SHIP-1 localization was explored further using SHIP-1 immunoreactivity and antibodies directed against microglia and astrocytes. SHIP-1 was not detected in microglia but was detected in astrocytes and this cell specific localization of immunoreactivity suggests that astrocytes can express SHIP-1. The expression of SHIP-1 in astrocytes may be involved in the pathogenesis of murine amyotrophic lateral sclerosis.

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

Assessment of Low Back Injury Risk in Residential Care Workers

Author: 
Date created: 
2004
Abstract: 

Low back injury continues to be a problem for residential care workers. There is an absence of an assessment tool that will determine probability of low back injury based on occupational exposure. This study analysed injury incidence among residential care workers and determined perceived stress and exertion, hand forces, postures, and task frequencies encountered in routine work tasks. Biomechanical analysis determined joint forces at the low back to be in the range of 467N to 381 1 N compression and 66N to 471 N A-P shear over all tasks. Task frequencies, joint compression forces, population low back injury data and material fatigue characteristics were used to model risk of low back injury as a function of occupational exposure. The fatigue model predicts that 50% of residential care workers will experience a low back injury by their eighth year of work experience, and 95% by their fifteenth year of work.

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

Physiological mechanisms of nutrient transport: Vitamin A and retinol-binding protein

Author: 
Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2009
Abstract: 

Biologically active metabolites of retinol (vitamin A) affect growth, differentiation, and survival of cells. Retinol-binding protein (RBP) is a specific circulatory transport protein for retinol and participates its delivery to cells. Based on evidence for receptor-mediated endocytosis of RBP, experiments were carried out to further characterize (a) the RBP receptor and (b) the fate of endocytosed RBP in a human epithelial cell line. Additional experiments were performed with mice to examine (c) possible age-related changes in tissue accumulation of injected RBP. The results provide the first size characterization of an RBP receptor in these cells, a 157 kDa species, and the first evidence for recycling of endocytosed RBP. Age-related decreases in transport were suggested by a 23-27% decrease in the accumulation of exogenous RBP in old vs. young tissues (early post-injection times). Additional work on related transport mechanisms was carried out for RBP and the iron carrier transferrin.

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

Neuromuscular and behavioural influences on balance and falls

Author: 
Date created: 
2009
Abstract: 

Falls are the number one cause of accidental injury and exert an especially heavy toll on the elderly. Most falls involve a common sequence of events. First, a particular event results in loss of balance. Second, there is a failed attempt at recovering balance, and finally, once the fall is "recognized" to be inevitable, attempts may be made to lessen its severity. My thesis research focuses on neuromuscular and behavioural aspects of balance maintenance and protective responses during falls. In Chapter 2 and 3, I describe efforts to develop and apply a novel technique to determine how risk for imbalance during daily activities depends on behavioural versus neuromuscular factors. Specifically, I developed the “Reach Utilization Test” to determine whether the tendency to approach imbalance is different between young and elderly women who resided either in nursing homes (Chapter 2) or in the community (Chapter 3). In Chapters 4 to 7, I focus on the measurement and analysis of protective responses during sideways falls. In Chapter 4, I describe the results of experiments to determine whether unexpected sideways falls in young adults elicit a common sequence of responses that might protect against hip fracture. I used a novel experimental paradigm which challenged participants to focus on maintaining balance after experiencing a single large perturbation, which in the vast majority of cases elicited a sideways fall. In Chapter 5, I describe the results of experiments to test whether the ability of humans to alter their body configuration during the fall depends on the time when the response is initiated. I hypothesized that a critical time window exists, beyond which one is unable to avoid hip impact. In Chapter 6, I describe the results of experiments to determine whether individuals are able to accurately recall the details of their falls. I addressed this question by interviewing young adults immediately after they experienced an unexpected sideways falls. Finally, in chapter 7, I describe results from a modelling study to address how fall severity depend on the cause of the fall (slip vs. trip).

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