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

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Compliant flooring for fall injury prevention in long-term care

Date created: 
2017-03-06
Abstract: 

A promising strategy for reducing the incidence and severity of fall-related injuries in long-term care (LTC) is to decrease the ground surface stiffness, and the subsequent forces applied to the body parts at impact, through installation of compliant flooring. Evidence about the feasibility of compliant flooring in LTC is extremely limited. My PhD research addresses this gap by conducting a comprehensive, multimethod evaluation of compliant flooring. Specifically, I investigate the feasibility of compliant flooring for fall injury prevention in LTC by synthesizing the available evidence (study 1), determining the effects of compliant flooring on external hand forces exerted by LTC staff when pushing wheeled equipment (study 2), and examining the barriers to and facilitators of implementing compliant flooring as perceived by key stakeholders (studies 3 and 4). In my first study, I conducted a scoping review to describe the extent, range, and nature of research activity on compliant flooring, and to identify research gaps and directions for future research. I found compliant flooring is a promising strategy for preventing fall-related injuries from a biomechanical perspective. Additional research is required, however, to determine whether compliant flooring prevents fall-related injuries in real-world settings, is a cost-effective intervention strategy, and can be installed without negatively affecting workplace safety. My second study compared the effects of flooring system and resident weight on the forces required by LTC staff to push floor-based lifts used to transfer residents. Compared to the conventional lift, the motor-driven lift substantially reduced forces in all experimental conditions and thus may help to address risk of work-related musculoskeletal injury. My third study examined the feasibility of compliant flooring from the perspective of organizational-level LTC stakeholders. My interview findings provide new evidence about facilitators and barriers that stakeholders consider in deciding to install compliant flooring in LTC, such as staff’s openness (or resistance) to change and flooring performance. My fourth study sought input about compliant flooring from additional stakeholders through a symposium. My findings suggest that while stakeholders perceive compliant flooring to add value to the LTC setting, there also remain significant informational and financial barriers to the uptake of compliant flooring. Overall, my thesis should inform planners and architects in the development of safer environments for vulnerable older adults, and improve policies and programs for fall injury prevention in LTC.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Dawn Mackey
Department: 
Science: Department of Biomedical Physiology and Kinesiology
Thesis type: 
(Dissertation) Ph.D.

A social ecological model of adherence to hip protectors in long-term care

Date created: 
2017-01-30
Abstract: 

Hip fractures among older adults living in long-term care (LTC) are debilitating and costly, and are nearly always caused by falls. If worn at the time of falling, specific types of hip protectors reduce fracture risk by 80%. However, the clinical value of hip protectors is compromised by poor user adherence in the wearing of these devices. My thesis provides insight into the factors governing adherence with hip protectors in LTC. In my first study, I conducted a systematic review of extant literature. A total of 1086 articles were identified, and of these, 28 met our inclusion criteria. Barriers and facilitators were grouped into four taxonomies: (i) system-related; (ii) caregiver-related; (iii) resident-related; (iv) hip protector-related. My second study involved the development and validation of the C-HiP index to measure commitment to hip protectors amongst paid care providers in LTC. Exploratory factor analysis yielded a factor structure consisting of two lower-order factors and a single higher-order factor. Expert evaluation by LTC clinicians provided evidence of content validity. Internal consistency was high (Cronbach’s alpha=0.96). My third study identified social ecological determinants of commitment to hip protectors by means of a cross-sectional survey (n=529). Mean (SD) commitment was 4.15 (0.71) out of 5.00. Commitment was associated with race/ethnicity, occupation, organizational tenure, awareness of a padded hip fracture, familiarity of hip protectors, perceptions of transformational leadership, communication, resident-provider relationship quality, and the existence of a champion of hip protectors within the home. Finally, I conducted a 12-month retrospective cohort study in fourteen publically subsidized LTC homes to identify factors governing adherence with hip protectors, and to examine the clinical value of hip protectors to prevent hip fractures. The percentage of residents who wore hip protectors during at least one fall was negatively correlated with regional socioeconomic deprivation (ρ=-0.630) and the percentage of residents with depression (ρ=-0.538), and was positively correlated with the percentage of residents paying for care privately (ρ=0.539) and who fractured their hip in the past 180 days (ρ=0.677). The relative risk of hip fracture was 0.36 (95% CI 0.14–0.90) in falls with hip protectors compared to falls without hip protectors.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Stephen Robinovitch
Department: 
Science: Department of Biomedical Physiology and Kinesiology
Thesis type: 
(Dissertation) Ph.D.

Thermal perception and physiological responses in males and females during mild cold exposures in different clothing ensembles

Author: 
Date created: 
2016-06-13
Abstract: 

In the first study of this thesis 10 males and 10 females walked on a treadmill with a ~10 km/h wind and an ambient temperature of -8°C. The hypotheses tested included: 1) females will have lower skin temperature and surface heat flux while all other physiological responses are similar when compared to male, 2) within each sex, an elasticized (E) coat versus a non-elasticized (NE) coat would give a diminished physiological strain and 3) that within each sex, the E coat versus the NE coat would give a better thermal comfort. Results in this first study showed some differences in physiological responses between the sexes, that males had higher thermal comfort ratings in an E versus a NE coat during exercise (p<0.05). In the second study, it was hypothesized that females would have greater sensitivity to skin temperature changes than males on the hand, back and chest. The results showed females versus males were less sensitive to temperature changes only on the chest (p <0.05). In conclusion, in the first study some physiological responses differed between the sexes, the E compared to the NE coat provided no beneficial physiological responses within each sex and finally the E versus the NE coat provided greater thermal comfort in males. In the second study females were less sensitive to cold stimuli on the chest compared to males.

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

Investigation and management of sudden unexpected death in the young in Canada

Author: 
Date created: 
2016-12-20
Abstract: 

Sudden unexpected death in the young, SUDY, is devastating for families, their communities and health care professionals. When no cause of death is identified after a thorough autopsy and other ancillary tests, “autopsy-negative” SUDY, it leaves families without answers as to why their loved one died. At least one third of autopsy-negative SUDY cases are attributed to an inherited cardiac disorder. Therefore, surviving relatives may be at risk of another tragic death if they are not referred for expert clinical assessment. The main focus of this dissertation was to explore the investigation and management of SUDY and SUDY-affected families in Canada with the end goal of developing guidelines for coroners and medical examiners to standardize their investigative practices. To achieve this goal, three studies were conducted. The first study determined the current practices of SUDY investigation by coroners and medical examiners by surveying Canadian death investigation agencies and cardiac electrophysiologists – clinicians with expertise in inherited cardiac disorders that can predispose individuals to SUDY. The findings revealed heterogeneous practices, particularly around post mortem tissue retention at autopsy and molecular genetic testing, supporting the need for SUDY investigation protocols, tissue retention, cause/manner of death classification and written recommendations for SUDY-affected relatives to undergo clinical assessment. The second study involved genetic testing of post mortem tissue retained from autopsy from a child SUD cohort in collaboration with the Manitoba Medical Examiner’s Office. We successfully identified variants that may assist in the diagnosis of 15% of autopsy-negative child SUD cases. We reported our findings to the medical examiner who informed the families of our cohort and recommended that they be clinically assessed to reduce the risk of future SUDY. In the final study, the findings from the first two studies, both limitations and successes, were combined with a systematic scoping review of published and grey literature on SUDY investigation guidelines. Seven recommendations were developed for Canadian death investigation agencies to standardize their approaches to SUDY investigation.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Glen Tibbits
Department: 
Science: Department of Biomedical Physiology and Kinesiology
Thesis type: 
(Dissertation) Ph.D.

The mechanics of the gastrocnemii-Achilles tendon complex during human cycling: Experimental and modelling approaches to predict in vivo forces

Date created: 
2016-08-30
Abstract: 

Skeletal muscle is the engine that produces force to power movement in humans and animals alike. To date the invasive nature of obtaining muscle-tendon forces in humans has limited our understanding of muscle function during coordinated locomotor tasks. Phenomenological, Hill-type models of skeletal muscle are often used, providing estimates of a muscle’s force as a function of its activation state, force-length, and force-velocity properties. However, few studies have examined the accuracy of whole muscle-tendon forces obtained from such models during in vivo motor tasks. The goal of my thesis was to develop, test, and refine methods to better quantify muscle mechanical output in humans, using ultrasound and electromyographic recordings, together with advanced Hill-type models. My first study developed techniques to non-invasively estimate in vivo Achilles tendon forces. I used ultrasound-based measures of tendon length and tendon mechanical properties to determine forces during cycling. In my second study, I compared gastrocnemii forces, predicted from a traditional Hill-type model with one contractile element, to force estimates derived from ultrasound-based tendon length changes. Because the traditional Hill-type model fails to account for variable activation states of different fibre types, I additionally tested a two-element model that includes both slow and fast contractile elements. I found that Hill-type models predicted 31-85% of the cyclists’ gastrocnemii forces across a range of conditions elicited, producing results comparable to those reported in animal models. Further, at higher cadences, the two-element model better estimated forces because it accounted for the increased recruitment of fast fibres. Traditional Hill-type models also neglect dynamic shape changes in contracting muscles, which may be important in modulating the velocities at which fascicles operate. My third study compared predictions of muscle architecture (fascicle lengths and pennation angles) generated from a 1D Hill-type model and additionally from 2D and 3D geometric models that allowed dynamic shape changes to occur. I found that the 1D model provided predictions of muscle architecture that were similar to the predictions of 2D and 3D models and that muscle shape changes and fascicle velocities were more closely linked to force than activation. Taken together, this research provides a non-invasive approach for studying in vivo muscle-tendon mechanics and testing the predictions of Hill-type models.

Document type: 
Thesis
File(s): 
Senior supervisor: 
James Wakeling
Department: 
Science: Department of Biomedical Physiology and Kinesiology
Thesis type: 
(Dissertation) Ph.D.

Psycho-Social Support for Patients with Cardiovascular Disease (CVD): Barriers to a Cardiac Rehabilitation Program (CRP)

Author: 
Date created: 
2016-07-28
Abstract: 

Cardiac Rehabilitation Programs (CRP) are effective behavioural interventions that reduce morbidity and mortality in patients with cardiovascular disease. Despite the myriad of benefits, participation remains sub-optimal with drop-out rates as high as 60%. Patients who discontinue CRP are under-treated and consequently, are at greater risk for further cardiac events. It is imperative to find alternative strategies to support to this high-risk population. The objectives of the present thesis were three fold: i) to identify baseline characteristics of participants who previously dropped-out of a CRP (chapter 2); ii) to assess self-efficacy among patients who complete a CRP versus those who drop-out (chapter 3); iii) to test the feasibility of an Internet-mediated VC intervention to provide ongoing psycho-social support among patients who previously dropped-out of a CRP (chapter 4).

Document type: 
Thesis
File(s): 
Senior supervisor: 
Scott Lear
Department: 
Science: Department of Biomedical Physiology and Kinesiology
Thesis type: 
(Thesis) M.Sc.

Reprogramming human peripheral blood mononuclear cells to inducible pluripotent stem cells (hiPSC): An examination of the efficacy of different methods

Date created: 
2016-07-28
Abstract: 

Modeling a disease “in a dish,” a new research tool to study human heart disease mechanisms, is becoming as popular as more established techniques such as the use of transgenic mice. The primary practical challenge of this “disease in a dish” method is efficiently directing human induced pluripotent stem cell (hiPSC) differentiation into the desired lineages, with the major concern being the variability within hiPSC clones.To generate a reliable in vitro model for inherited cardiac diseases and address the variability problem, characteristics of hiPSCs derived from the blood of four human donors using both the episomal and Sendai virus reprogramming systems were examined. The hiPSC-cardiomyocytes (hiPSC-CMs) generated were then characterized according to their cardiac-specific gene expression properties. No differences were observed on the effect of the reprogramming system on expression of pluripotent genes in iPSCs but differences were observed in expression of cardiac specific genes in cardiomyocytes derived from those iPSCs despite a high variance in the analysis.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Glen Tibbits
Department: 
Science: Department of Biomedical Physiology and Kinesiology
Thesis type: 
(Thesis) M.Sc.

Characterization of Epithelial Progenitors in Normal Human Palatine Tonsils

Date created: 
2016-05-17
Abstract: 

The palatine tonsils are a collection of lymph nodes overlaid by stratified non-keratinized epithelium that invaginates deep into the tissue, forming tonsillar “crypts” where ingested and inhaled pathogens are collected and initiate an immune response followed by transepithelial lymphocyte infiltration. The dynamic nature of this site suggests the existence of primitive cells responsible for the constant tissue repair and regeneration; however, such cells in the tonsils have not been characterized. Human Papillomavirus (HPV)-associated cancer of oropharynx is a global health concern that is on the rise, with HPV16 oncoproteins E6/E7 frequently detected in the epithelium of tonsillar crypts. It is hypothesized that the long-term self-renewing progenitor cells are the target of HPV-induced malignancy, but the lack of a method to specifically study these critical cells has been a barrier to further investigation. In this study, I have developed and optimized the methodology to identify, isolate and quantitate epithelial progenitors from human palatine tonsil. I show that tonsillar progenitors that form colonies in vitro in 2D colony assays and differentiate into multilayered epithelial tissues in a 3D culture system are CD44+NGFR+ and present in both surface and crypt regions. Transcriptome analysis indicates a high similarity between CD44+NGFR+ cells in both regions, although those isolated from the crypt contained a higher proportion of the most primitive (holo)clonogenic cells. The method was then applied to study effects of HPV infection on purified CD44+NGFR+ cells from both regions. Lentiviral transduction of CD44+NGFR+ cells with HPV16 E6/E7 oncogenes prolonged their growth in 2D cultures and caused aberrant differentiation in 3D cultures. Interestingly, in the presence of the normal cells, the E6/E7-transduced cells proliferated more slowly in 2D cultures and formed uniquely heterogeneous epithelial structures displaying varying degrees of perturbation in 3D cultures suggesting possible inhibitory effects of the cocultured normal cells. The system developed and presented in this thesis allows for a targeted approach to study a specific subset of epithelial cells purified from the tonsillar crypts and their response to E6/E7 infection, setting the stage for addressing many unanswered questions pertaining to the early stages of tonsillar oncogenesis.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Miriam Rosin
Department: 
Science: Department of Biomedical Physiology and Kinesiology
Thesis type: 
(Dissertation) Ph.D.

An atomic scale measurement from the voltage sensor in hERG channels using lanthanide-based resonance energy transfer

Date created: 
2016-06-16
Abstract: 

The cardiac human ether-a-go-go related gene (hERG) channel is a voltage-gated potassium (Kv) channel that plays a fundamental role in cardiac repolarization. The importance of the hERG channel derives from its unusually slow activation (opening) and deactivation (closing) processes. Like other Kv channels, structural reconfigurations of the hERG voltage sensor upon membrane depolarization and repolarization underlie channel activation and deactivation, respectively. However, specific rearrangements of the voltage sensor that may dictate the unique slow activation and deactivation in hERG channels remain unclear. Lanthanide-based resonance transfer (LRET) is a spectroscopic technique that has previously demonstrated an ability to provide quantitative description of voltage sensor dynamics in an archetypal Kv channel. In this report, we outline a rationalized approach to applying LRET to examine hERG channel voltage sensor dynamics that may be of physiological significance. As a result, we report the first distance measurement from voltage sensors across the hERG channel pore.

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

Ischemia – reperfusion destabilizes rhythmicity in immature atrio-ventricular pacemakers: a predisposing factor for postoperative arrhythmias

Author: 
Abstract: 

Post-operative arrhythmias, such as Junctional Ectopic Tachycardia (JET) and atrioventricular (AV) block, are serious post-operative complications for children with congenital heart disease 1. We hypothesize that these arrhythmias arise within the AV node because of an ischemia-reperfusion (I/R) insult in the setting of immature myocytes, exacerbated by post-operative inotropy. Rabbit whole heart models of post-operative arrhythmias were generated, focusing on three primary risk factors: age, I/R exposure and the application of dopamine, an inotropic agent. Using optical mapping technology, neonatal rabbit hearts were found to experience persistent post-ischemia arrhythmias of differing severity while mature hearts exhibited no arrhythmias or transient ones, when the three risk factors were varied.Compared to rabbit mature hearts, rabbit neonatal whole hearts demonstrated a susceptibility to I/R insults resulting in alterations in automaticity. An analogous susceptibility may predispose human neonates to post-operative arrhythmias such as JET and AV block.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Glen Tibbits
Department: 
Science: Department of Biomedical Physiology and Kinesiology
Thesis type: 
(Thesis) M.Sc.