Medicine and Health Sciences Commons^™

Contextual Control Of Orienting Eye-Head Gaze Shifts In The Monkey, Brendan B. Chapman

Electronic Thesis and Dissertation Repository

Vision is one of the principal methods used by primates to acquire information about the surrounding environment. As a result, both humans and monkeys have a highly evolved oculomotor system that functions to rapidly relocate the line of sight to areas of interest. These orienting movements are called gaze shifts. Gaze shifts commonly include the coordinated movement of the eyes-in-head and the head-in-space. This thesis examines the muscular and neural control of orienting head movements.

The contextual control of behavior is important as it allows one to act appropriately in response to different situations. A common task used to examine …

The Effects Of Low Protein During Gestation On Mouse Pancreas Development And Beta Cell Regeneration, Aaron R. Cox

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Effects of a low protein (LP) diet during gestation on the metabolism of rat offspring have been well characterized and leads to glucose intolerance in adulthood. It is unknown how LP impacts endocrine pancreas development in the mouse, or whether this affects future β-cell plasticity. Streptozotocin (STZ) – induced β-cell injury has been demonstrated to be followed by β-cell regeneration in young animals, but the mechanism(s) of regeneration are not clear. Our objective was to characterize a mouse model of maternal LP, in addition to identifying factors that contribute to the long term development of glucose intolerance and the mechanism …

Modeling Lung Tissue Motions And Deformations: Applications In Tumor Ablative Procedures, Ali Sadeghi Naini

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Various types of motion and deformation that the lung undergoes during minimally invasive tumor ablative procedures have been investigated and modeled in this dissertation. The lung frequently undergoes continuous large respiratory deformation, which can greatly affect the pre-planned outcome of the operation, hence deformation compensation becomes necessary. The first type of major deformation involved in a target lung throughout a tumor ablative procedure is the one encountered in procedures where the lung is totally deflated before starting the operation. A consequence of this deflation is that pre-operative images (acquired while the lung was partially inflated) become inaccurate for targeting the …

Mechanisms Of Atrial Arrhythmia: Investigations Of The Neuro-Myogenic Interface In The Mouse, Jari Michael Tuomi

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Arrhythmia mechanisms rely on multiple factors including structural (myogenic), nervous (neurogenic), and interrelated (the neuro-myogenic interface) factors. I hypothesized that due to this neuro-myogenic interface, the intrinsic cardiac autonomic nervous system (ICANS) is involved in most atrial arrhythmias. This thesis also provides a "Threshold Model" as a tool to assess the role of different physiological factors influencing arrhythmia. This model allows relative comparison and interpretation of the role of various factors influencing arrhythmogenesis. The mouse allows relatively simple manipulation of genes to determine their role in arrhythmia. This thesis determined what atrial arrhythmias are inducible in the mouse (in vivo) …

Assessing And Improving 4d-Ct Imaging For Radiotherapy Applications, Greg Pierce

Electronic Thesis and Dissertation Repository

Lung cancer has both a high incidence and death rate. A contributing factor to these high rates comes from the difficulty of treating lung cancers due to the inherent mobility of the lung tissue and the tumour. 4D-CT imaging has been developed to image lung tumours as they move during respiration. Most 4D-CT imaging methods rely on data from an external respiratory surrogate to sort the images according to respiratory phase. However, it has been shown that respiratory surrogate 4D-CT methods can suffer from imaging artifacts that degrade the image quality of the 4D-CT volumes that are used to plan …

Characterization Of Quadriceps Neuromuscular Function In Knee Osteoarthritis, Michael James Berger

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PURPOSE: The purpose of this thesis was to characterize quadriceps neuromuscular dysfunction in patients with knee osteoarthritis (OA). Concerns pertaining to study design in this patient population (e.g. disease severity criteria and muscle imaging outcome measures) were also addressed.

METHODS: Five studies were undertaken using data acquired from volunteers recruited at the local institution and from participants in the public source dataset of the Osteoarthritis Initiative (http://oai.epi-ucsf.org/datarelease/). Clinical disease severity was evaluated with the Western Ontario and McMaster Osteoarthritis Index (WOMAC). Radiographic severity was evaluated with Kellgren-Lawrence Grading (KLG). Quadriceps muscle isometric strength and isotonic power were measured …

The Professional Practice Leader: The Role Of Organizational Power And Personal Influence In Creating A Professional Practice Environment For Nurses, Sara L. Lankshear

Electronic Thesis and Dissertation Repository

Professional Practice Leadership (PPL) roles were introduced in response to health care professionals’ concerns about the loss of professional autonomy and other possible negative consequences on professional practice arising out of the widespread implementation of program management during health care restructuring. Despite the extensive implementation of the PPL role in Ontario, there is a paucity of empirical studies examining the impact of the PPL role. The main purpose of this study was to address this knowledge gap by determining the role of organizational power and personal influence in enabling the PPL to fulfill their role functions toward creating a positive …

Glutamatergic Metabolites And Gray Matter Losses In Schizophrenia: A Longitudinal Study Using In Vivo Proton Magnetic Resonance Spectroscopy, Naoko Aoyama

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Approximately one in hundred people suffer from schizophrenia. Current medications partially improve the symptoms. There is no cure. Glutamate, an excitatory neurotransmitter, is a possible cause of the schizophrenia symptoms. Excessive glutamate release eventually leads to neurodegeneration. Longitudinal studies are necessary to observe the neurodegenerative process.

Seventeen schizophrenia patients and 17 healthy volunteers underwent proton magnetic resonance spectroscopy (MRS) and imaging to measure neurochemical and structural changes in vivo. Metabolite levels were measured from a 1.5cm³ voxel in the anterior cingulate and thalamus using the stimulated echo acquisition mode sequence. Gray matter (GM) was assessed with voxel-based morphometry …

Design And Syntheses Of Fluorescent Cytosine Analogues, David W. Dodd

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The avid hybridization of peptide nucleic acid (PNA) to DNA and RNA along with the molecule’s biological stability has led it to be used in both antisense and antigene capacities. PNA acts against translation via a steric blockade mechanism. It is therefore reasonable to assume that increased heteroduplex stability could lead to increased potency. Two ways of doing this were explored. I) N-Terminal attachment of a platinous chloride chelating moiety to PNA complementary to Xenopus noggin was synthesized with the objective of selective, covalent platination of the target transcript in vivo. Phenotypes consistent with knockdown of the selected …

Fluid Percussion Injury In The Rat As An Animal Model Of Concussion: Cumulative Effects Of Repeated Concussion And Its Treatment By Anti-Cd11d Antibody, Sandy Rc Shultz

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Traumatic brain injury is a global health concern with limited treatment options currently available. Concussion is the most common form of traumatic brain injury, and although a single concussion rarely results in long-term neurological dysfunction, repeated concussion can result in cumulative damage and chronic neurodegenerative disease. However, little is known about the factors and mechanisms of concussion involved in these detrimental effects. Animal models provide a means to examine the factors and mechanisms involved in traumatic brain injury, as well as potential treatments, in experiments that cannot be conducted using human participants. In the present thesis a fluid percussion model …

Development And Testing Of A Low Vision Product Selection Instrument (Lv-Psi): A Mixed-Methods Approach, Daniel Fok

Electronic Thesis and Dissertation Repository

In Canada, it is conservatively estimated that $46 million is lost per annum from low vision (LV) assistive technology device (ATD) abandonment alone. The proper matching of the person and the technology during the selection process has been theorized as necessary to mitigate inappropriate abandonment. In the current dissertation, a mixed-methods approach with qualitative and quantitative study components was used to develop and test a LV product selection instrument (LV-PSI) that may help with the matching process.

The key qualitative aspect of the study included two qualitative research sessions with LV participants (N=10). Each session was made up of two …

Depressive Symptoms In Mothers Of Children With New-Onset Epilepsy: A Prospective Study, Mark Anthony Ferro

Electronic Thesis and Dissertation Repository

Having a child diagnosed with a chronic illness such as epilepsy is a major source of stress for caregivers. Up to half of mothers of children with epilepsy are at increased risk for clinical depression and symptoms of maternal depression are associated with poorer health outcomes in these children. The purpose of this study was to: 1) estimate the prevalence and course of depressive symptoms over 24 months among mothers of children with new-onset epilepsy; 2) identify subgroups of mothers that share similar trajectories of depressive symptoms; and, 3) assess the family factors involved in the causal pathway between maternal …

From Isolated Tumour Cells To Overt Lymph Node Metastases: Biological And Imaging Studies On The Development Of Experimental Lymph Node Metastases, Michael M. Lizardo

Electronic Thesis and Dissertation Repository

Metastatic colonization and establishment of overt lymph node (LN) tumours indicates poor prognosis for cancer patients. However, the basic biology that influences the development of LN metastasis is poorly understood due to the lack of basic animal models. The following work provides a new lymph node experimental metastasis assay (LEMA) that permits the assessment of tumour cell fate after they arrest in draining LNs. In using this new model, we discovered that only 8% of the tumour cells that arrive in the LN are successful in forming overt tumours. This work also explored the use of imaging approaches to monitor …

A Model System For Rapid Identification And Functional Testing Of Genes Involved In Early Breast Cancer Progression, Lesley H. Souter

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Early breast cancer progression involves advancement through specific morphologic stages including atypical ductal hyperplasia (ADH), ductal carcinoma in situ (DCIS) and invasive mammary carcinoma (IMC), although not always in a linear fashion. Histological studies have examined differences in breast tissues representing these stages of progression, but model systems which allow for experimental testing of factors influencing transition through these stages are scarce. The purpose of these studies was to develop a 3D in vitro model of early breast cancer progression that reflected the in vivo sequence of events, and to use this system to identify and functionally test genes important …

Assessment Of Occupational Competence In Dementia: Identifying Key Components Of Cognitive Competence And Examining Validity Of The Cognitive Competency Test, Briana M. Zur

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Considering the links between dementia and everyday living, occupational therapists are called upon to make recommendations regarding appropriate living arrangements for persons with dementia. Re-framed as occupational competence, this is often accomplished by an evaluation of cognitive competence. Within the context of an aging population, a key question is how to best inform decisions regarding occupational competence, using cognitive competence as an indicator. The Cognitive Competency Test (CCT) is a tool used to evaluate cognitive competence and inform judgments about occupational competence in individuals with dementia. This thesis incorporates two studies that identified cognitive components that predict occupational competence in …

Client-Provider Relationships In A Community Health Clinic For People Experiencing Homelessness: A Critical Ethnography, Abram Oudshoorn

Electronic Thesis and Dissertation Repository

People who are experiencing homelessness have the highest rates of morbidity, and the lowest age of mortality in Canada. The importance of health care relationships in addressing the needs of people who are experiencing homelessness has been demonstrated. However, two gaps still exist in the literature. Firstly, the dialectical relationship between space/place and social relations has been neglected in the context of health care and homelessness. Secondly, there is a dearth of research on the role of formal and informal policies on the enactment of client-provider relationships in this context. Therefore, in this study three research questions are addressed: 1) …

The Characteristics Of Successful Evidence Retrieval By Nephrologists And The Impact Of Pubmed Search Filters, Salimah Shariff

Electronic Thesis and Dissertation Repository

Background: Clinicians frequently search PubMed to guide patient care. This study investigated the factors that impact successful searching and the utility of PubMed search filters.

Methods: A random sample of nephrologists was surveyed between 2008 and 2010; 160 valid responses were received (72% response rate). One group of 60 respondents was presented with the same two clinical questions, while the other 100 were each presented with a unique clinical question. The clinical questions were based on recently published systematic reviews. Respondents provided the search terms they would type into PubMed to address their clinical question(s). All physician-provided searches …

The Role Of Granulocyte Colony-Stimulating Factor In The Intestinal Immune System And The Response To Probiotics, Andrew J. Martins

Electronic Thesis and Dissertation Repository

Loss of immunoregulation in the intestine results in inflammation, such as is observed in the chronic, relapsing, inflammatory bowel diseases (IBD), Crohn's disease and ulcerative colitis. However, our understanding of this process remains incomplete. The cytokine granulocyte-colony stimulating factor (G-CSF) is an important stimulator of granulopoiesis in steady-state and during inflammation, but has also been shown to have anti-inflammatory effects and is a potential therapeutic for IBD. In addition, certain strains of bacteria, termed probiotics, have been postulated to have anti-inflammatory effects in the intestine. The mechanisms by which these strains of bacteria elicit anti-inflammatory effects are not fully understood. …

Quantification Of Pulmonary Ventilation Using Hyperpolarized 3he Magnetic Resonance Imaging, Lindsay Mathew

Electronic Thesis and Dissertation Repository

Smoking-related lung diseases including chronic obstructive pulmonary disease (COPD) and lung cancer are projected to have claimed the lives of more than 30,000 Canadians in 2010. The poor prognosis and lack of new treatment options for lung diseases associated with smoking are largely due to the inadequacy of current techniques for evaluating lung function. Hyperpolarized ³He magnetic resonance imaging (MRI) is a relatively new technique, and quantitative measurements derived from these images, specifically the ventilation defect volume (VDV) and ventilation defect percent (VDP) have the potential to provide new sensitive measures of lung function. Here, we evaluate the reproducibility …

Hemodynamics In The Stenosed Carotid Bifurcation With Plaque Ulceration, Emily Y. Wong

Electronic Thesis and Dissertation Repository

The presence of irregular plaque surface morphology or ulceration of the atherosclerotic lesion has been identified as an independent risk factor for ischemic stroke. Doppler ultrasound (DUS) is the most commonly performed non-invasive technique used to assess patients suspected of having carotid artery disease, but currently does not incorporate the diagnosis of plaque ulceration. Advanced Doppler analyses incorporating quantitative estimates of flow disturbances may result in diagnostic indices that identify plaque ulcerative conditions. A technique for the fabrication of DUS-compatible flow phantoms was developed, using a direct-machining method that is amenable to comprehensive DUS investigations. In vitro flow studies in …

Ethical Challenges In Cluster Randomized Trials, Andrew Mcrae

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Research Questions: This dissertation examines how ethical challenges in CRTs are addressed in practice. This dissertation also provides guidance as to who must be considered a research subject in a CRT, and when consent must be sought from research subjects.

Methods: The association between consent practices in healthcare CRTs and particular trial features were examined using multivariable logistic regression modelling. Information on ethical challenges encountered by CRT researchers in practice was obtained by analyzing semi-structured interviews with experienced CRT investigators. Two normative questions, “Who is the research subject in CRTs?” and “When is consent required in CRTs?” were also addressed. …

Effects Of Work Environments On Nursing And Patient Outcomes, Nancy M. Purdy

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Nurses are leaving the profession due to high levels of job dissatisfaction arising from current working conditions characterized by heavy workloads, limited participation in decision making and lack of development opportunities (Canadian Health Services Research Foundation [CHSRF], 2006a). To gain organizational support for workplace improvements and thereby improve nursing retention, evidence is needed to demonstrate the impact of the work environment on patient care. The purpose of this study was to determine the relationship between nurses' perceptions of their work environment and the quality and risk outcomes for both the patient and the nurse. Kanter's (1977, 1993) theory of structural …

A Stakeholder Generated Conceptualization For Successful Return To Work Outcome Evaluation: A Concept Mapping Approach, Rhysa Leyshon

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Measurement of return to work (RTW) lacks attention to outcomes of relevance to all stakeholders. The objective of this thesis was to define what constitutes a successful RTW outcome from a stakeholder perspective and determine how to best measure it. A concept mapping method was used to create a conceptualization of successful RTW outcome based on indicators of interest and importance to various stakeholders. RTW researchers were questioned and the literature was searched for measures that mapped to the conceptualization and concepts. Stakeholders, made up of RTW consumers and providers, generated 48 indicators of successful RTW which were subsequently grouped …

Improvements In Cardiac Spect/Ct For The Purpose Of Tracking Transplanted Cells, Eric Sabondjian

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Regenerative therapy via stem cell transplantation has received increased attention to help treat the myocardial injury associated with heart disease. Currently, the hybridisation of SPECT with X-ray CT is expanding the utility of SPECT. This thesis compared two SPECT/CT systems for attenuation correction using slow or fast-CT attenuation maps (mu-maps). We then developed a method to localize transplanted cells in relation to compromised blood flow in the myocardium following a myocardial infarction using SPECT/CT. Finally, a method to correct for image truncation was studied for a new SPECT/CT design that incorporated small field-of-view (FOV) detectors. Computer simulations compared gated-SPECT reconstructions …

Mapping The Flip Angle In Magnetic Resonance Imaging Using The Accelerated 3d Look-Locker Sequence, Trevor P. Wade

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In the ongoing quest to extract more information from MRI images, there has arisen a need to rapidly map the flip angle. This has been primarily driven by the shift to stronger main field strengths, which bring with them improved SNR, but also new difficulties. In particular, the radio frequency field used to excite the magnetization can no longer be assumed uniform at field strengths of 3 Tesla and above. New rapid quantitative imaging techniques, such as DESPOT1 and DESPOT2, rely on accurate knowledge of the flip angle, and while this could safely be assumed to be the prescribed value …

The Health Of Ontario’S Transgender Communities: Prevalence Of And Risk Factors For Depression, "Do-It-Yourself" Transitions, And Health Effects Of Cross-Sex Hormones And Surgeries, Nooshin Khobzi

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The purpose of this dissertation was to develop an understanding of, and draw attention to, the health and service access issues faced by trans (transgender, transsexual, or transitioned) Ontarians. This thesis is based on the Trans PULSE Project, a community-based research (CBR) initiative whose goal is to improve the health of trans people. Data collection was carried out between May 2009 and April 2010 using a quantitative survey. Trans participants were recruited through respondent-driven sampling (RDS), a network-based sampling method developed for the recruitment of hidden populations. Weighted prevalence estimates and 95% confidence intervals were calculated for all variables of …

Physical Function During Performance-Based Tasks And Throughout Daily Life. Is It Different Across Levels Of Frailty?, Olga Theou

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The overall aim of this thesis was to provide a more focused understanding about the physical function of older women across levels of frailty. The specific aims were: 1) Examine the physical function of older women across levels of frailty during performance-based tasks and throughout their normal daily life; and 2) Review the effectiveness of current exercise interventions for the management of frailty. To answer these aims an observational study of community-dwelling older women (63-100 years) from rural Greece and a comprehensive systematic review on the impact of exercise on frail older adults were conducted. The performance-based measures that had …