26734 research outputs found
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The Development and Characterization of Three-Colour Fluorescence Cross-Correlation Spectroscopy
No full textExpanding on theoretical work by Heinze et al.1, an optical setup to experimentally realize three-colour fluorescence cross-correlation spectroscopy (3C-FCCS) was designed. This instrument simultaneously collects and correlates fluorescence data from three colour channels, allowing real-time tracking of three-coloured species in complex solutions. To examine 3C-FCCS theory, a nanobarcode test particle, which physically linked three fluorophores was selected and characterized. These nanobarcode particles, capable of producing a triple cross-correlation decay, facilitated proof-of-concept experiments. 3C-FCCS was shown to be capable of measuring the concentration of nanobarcode particles in solution exclusively containing nanobarcode particles and solution containing nanobarcodes outnumbered by background quantum dots at a ratio of 800:1. 3C-FCCS was used to investigate a simple DNA-based nanostructure. These experiments illustrate that 3C-FCCS is a compelling technique with a plethora of potential applications, ranging from investigating hierarchical nanoassembly to biological reactions.indefinit
The Role of Myeloid Derived Suppressor Cells in the Interleukin-10 Model of Colitis-Associated Cancer
No full textChronic inflammation in the colon is a risk factor for developing colorectal cancers, one of the leading causes of cancer related deaths in Canada. A hallmark feature of inflammation is the recruitment of leukocytes. Of interest in this thesis are the heterogenous population of Gr1+/CD11b+ Myeloid Derived Suppressor Cells (MDSC). These cells are recruited to tumour sites, but have recently also been shown to be increased during inflammation. A key regulator of inflammation and leukocyte recruitment to the gut is the innate immune receptor TLR4. In this thesis we use the IL-10-/- mouse model to examine the role of MDSC in colitis-associated cancer.
Our preliminary data in an IL-10 TLR4 double knock out mouse revealed an increased cancer incidence in the absence of TLR4. We hypothesized that MDSC contributed to cancer development in the IL-10-/- and TLR4 signaling modulates cancer development through an effect on MDSC function or recruitment.
Our studies demonstrated enhanced numbers of Gr1+/CD11b+ cells in the colons of IL-10-/- mice. Characterization of these cells revealed an active immunosuppressive phenotype demonstrated by activity of NOS II and Arginase I enzymes and suppression of T-cell proliferation. Pharmacological targeting of MDSC decreased dysplasia development. Enriching the MDSC pool using adoptive transfer was associated with enhanced neoplasia development in the IL-10-/- mice. These data suggest that MDSC contribute to inflammation associated tumour development.
In the absence of TLR4, IL-10-/- mice recruited increased levels of MDSC to the colon. MDSC numbers correlated with the levels of cancer development in this model. TLR4 competence did not affect the immunosuppressive function of MDSC. We identified MCP-1 and SDF-1 as MDSC chemoattractants. Examination of colonic tissue demonstrated increased MDSC chemoattractant expression levels in the absence of TLR4 before tumour development in the IL-10 deficient model.
Our data identify a link between TLR4 signaling and MDSC recruitment to the gut during inflammation and demonstrate that MDSC recruitment drives cancer development.indefinit
Supervision Conversations: Negotiating Professional Development through Talk
No full textResearch on assessing supervisees’ professional development (PD) has been primarily focused on either exploring subjective experiences or refining objective aspects of professional competence. As a complement, this study takes a situated/dialogical approach to explore how PD assessments are transacted and conversationally accomplished in actual supervision practice (i.e., how supervisory dyads bring about shared understandings vis-à-vis the supervisee’s PD through supervisory talk).
Informed by Practice Theory and Ethnomethodology, I explore episodes of supervisory talk that four supervisory dyads regarded as significant to the supervisees’ PD (i.e., significant episodes). My focal discursive analysis of six significant episodes examines how participant supervisory dyads express, recognize, account for, negotiate and eventually agree upon relevant aspects of supervisees’ PD. I describe five “big” Practices/Outcomes, and three clusters of “small” conversational practices, through which participants negotiated their understandings of supervisees’ PD. I further suggest that PD assessments are ubiquitous, negotiated, and reflexive in the supervisory process. Finally, I discuss implications for supervision theory, research, and practice.indefinit
Physical Activity and Nutrition in Head and Neck Oncology: Developing a Patient-Oriented, Clinic-Supported Program
No full textHead and neck cancer is a debilitating disease associated with a variety of acute and chronic symptoms and treatment-related side effects. Effective rehabilitation programs are necessary to improve patient physical and psychosocial outcomes following diagnosis. In recent years, the role of physical activity in improving patient physical and psychosocial functioning following a cancer diagnosis has become apparent. With improved rates of survival, in particular within subgroups of head and neck cancer such as the human papilloma virus positive group, the role of physical activity is of interest
The purpose of the present research was to: 1) review existing head and neck cancer and physical activity literature; 2) evaluate the feasibility of a group-based resistance training pilot program in managing symptoms and side effects following diagnosis; 3) assesses differences in physical activity participation between human papilloma virus positive versus human papilloma virus negative head and neck cancer patients; 4) examine the physical and psychosocial impact of a 12-week physical activity and lifestyle intervention during and immediately following radiation therapy; 5) and summarize the key findings from these studies to provide updated conclusions regarding the role of physical activity for head and neck cancer survivors.
This work highlights the role of physical activity and a health behaviour change intervention in head and neck cancer patients from the point of diagnoses onwards. Although the randomized controlled trial conducted revealed no significant added benefit of a lifestyle intervention on lean body mass maintenance during radiation treatment, it is clear from the pilot work and reviewed literature that physical activity plays a valuable role in head and neck cancer survivorship. With low physical activity participation following diagnoses, especially among human papilloma virus negative head and neck cancer patients, targeted evidence-based clinic and community based programs designed to support patients with physical activity adoption and adherence are required. Ongoing work will be valuable in further clarifying the specific role of physical activity for these patients and how it can be tailored for maximized symptom and side effect management, ultimately improving head and neck cancer survivorship.indefinit
Altering Inhibitory Extracellular Matrix Promotes Remyelination
No full textRemyelination is the generation of new myelin sheaths after injury, and is accomplished by oligodendrocyte precursor cells (OPCs) that proliferate, migrate, and differentiate into myelin-forming oligodendrocytes. A number of lesion-associated factors have been identified that interfere with the remyelination response. Chondroitin sulfate proteoglycans (CSPGs) are a family of extracellular matrix molecules that provide structural rigidity to tissues and act as signalling molecules to neurons and glia in the developing nervous system. After injury, CSPGs become highly upregulated by astrocytes as part of the glial scar and restrict axonal regeneration. The role of injury-induced CSPG deposition on OPCs and remyelination is far less understood. In this thesis, I characterized a potent inhibitory phenotype of murine OPC adhesion and process outgrowth cultured on CSPGs in vitro. I explored the various mechanisms underlying this inhibitory response, including candidate receptors, downstream signalling molecules, and structural ligands on CSPGs through selective enzymatic degradation. I screened 245 orally available, Health Canada approved medicines for their ability to overcome OPC process outgrowth in the presence of CSPGs, and found a persistent inhibitory phenotype for all drugs tested. Lastly, I assessed the utility of a novel CSPG synthesis inhibitor, fluorosamine, and found that it reduced CSPG synthesis by astrocytes, resulting in a more permissive environment for OPC growth in vitro. Following experimental demyelination with lysolecithin in vivo, fluorosamine treatment reduced the deposition of CSPGs and enhanced OPC maturation and remyelination. Altering the inhibitory microenvironment after injury may be beneficial for promoting repair in a number of neurological diseases.indefinit
Microtubules and fertilization: The MEI-1/Katanin mediated cytoskeletal transition from meiosis to mitosis in the developing C. elegans embryo
No full textDuring embryonic development, dramatic changes of the C. elegans cytoskeleton
occur in the transition from the meiosis to mitosis requiring precise regulation of molecules specific to each type of spindle. The microtubule severing complex, MEI-1/MEI-2, is required for C. elegans meiotic spindle formation, but must be inactivated to prevent disruption of mitosis. There are several redundant pathways involved in this tightly regulated process. In order to determine how known genes of these pathways function relative to one another, I have developed a robust antibody-staining assay to measure anti-MEI-1 protein levels based on total pixel intensity in early embryogenesis. Using this assay, I have shown that APC and MBK-2 act strictly sequentially with one another to degrade MEI-1. I have also shown that ectopic MEI-1 staining in cul-2 and rfl-1 are enhanced by mel-26 and not by mbk-2 indicating that CUL-2 and MBK-2 are working together to degrade MEI-1 in parallel to the MEL-26/CUL-2 pathway and that RFL-1 is activating CUL-2 in this process. hecd-1 ectopic MEI-1 staining was not enhanced by any of the known regulatory genes in this process and might be inhibiting an activator of MEI-1. This project will assist in decoding the key regulatory molecules of the developmental remodelling in early embryos.Noforeve
Low Social Support as a Risk Factor for a Major Depressive Episode in Canadian Community Dwelling Seniors
No full textBackground: The proportion of Canadians aged 65 years of age and older is rapidly growing. While major depression has consistently been identified in the literature as a major health concern, little research exists on geriatric depression in Canada. Current research on risk factors for depression in seniors has been generated almost exclusively through cross-sectional studies. A small number of longitudinal studies have been conducted, though their applicability is limited by short study periods, strictly defined study populations, and focus on only one or two potential risk factors. No longitudinal studies on seniors’ depression have been conducted in Canada at the population level despite the availability of data to do so (the National Population Health Survey, or NPHS). Using the NPHS, this thesis explored the relationship between social support and major depression in Canadian community-dwelling seniors.
Methods: I assessed types and levels of social support using the Medical Outcomes Study Social Support Survey. Major depressive episode (MDE) in the past 12-months was assessed using the Composite International Diagnostic Interview – Short Form for Major Depression (CIDI-SFMD) and Anatomic Therapeutic Classification (ATC) Drug codes for anti-depressant usage. Demographic characteristics and health characteristics of respondents and non-respondents were examined and compared. The 12-month prevalence and 2- and 8-year incidence proportions of MDE were estimated. Multivariate logistic regression modeling was used to examine the association between social support and the 8-year risk of MDE
Results: In participants aged 65 years of age and older, the 12-month prevalence of MDE was 6.50% (95% CI 5.28%-7.63%). The 2-year and 8-year incidence of MDE was estimated to be 4.54% (95% CI 3.38%-5.60%), and 13.09% (95% CI 11.27%-14.90%), respectively. Incidence was higher among women, those with a chronic condition, those with a restriction to activity, a pain problem or a mobility problem. In multivariate modeling low positive social interaction (OR 1.59, 95% CI 1.12-2.25, p=0.009) and low emotional social support (OR 1.53, 95% CI 1.09-2.14, p=0.013) were significantly associated with the risk of MDE. The association between tangible social support and MDE was modified by income (OR 0.2.70, p=0.019), with those of low income and low tangible support at higher risk of MDE (OR 2.66, 95% CI 1.02-6.89, p=0.044). The relationship between both tangible support (OR 0.43, p=0.025) and affection support (OR 0.35, p=0.008) with MDE was modified by the presence of a pain problem. In both cases, social support was not related to MDE if a pain problem was present. Among those without a pain problem, low tangible social support (OR 2.63, 95% CI 1.03-6.75, p=0.044) and low affection social support (OR 2.09, 95% CI 1.33-3.28, p=0.001) was associated with higher risk of MDE.
Conclusion: Social support is an important risk factor for MDE in seniors, even after adjustment for a number of health and demographic variables. The relationship between some types of social support (tangible and affection social support) and MDE may be modified by the presence of a pain problem. It is therefore important that chronic pain issues be adequately controlled in seniors, as these may counter the positive effects of high levels of social support. Living arrangement was not found associated with depression in our study, suggesting that seniors aging in the community versus a long-term care facility are not at increased risk of depression, provided they have high levels of social support. Efforts such as community programs may therefore be important in helping ensure high levels of positive social interaction and social support in community-dwelling seniors.indefinit
Construction and Characterization of a B. burgdorferi strain with Conditional Expression of the Essential Telomere Resolvase, ResT
No full textDuring DNA replication in Borrelia burgdorferi, replication of linear elements results in an inverted dimer repeat of the telomere which is subsequently resolved by the telomere resolvase, ResT. ResT has been demonstrated as essential and a knock-out strain has never been produced. Using a conditional expression system a resT knock-out strain has been produced and used to investigate the effects of ResT depletion of spirochete viability as well as genome stability. ResT depleted spirochetes ceased to divide after ResT depletion, however, remained viable up to 16 days suggesting an arrested state of the spirochetes. Southern blots of the DNA revealed a shift of linear plasmid DNA to a higher molecular weight representing the circular intermediate. DNA replication did not continue in spirochetes after ResT depletion suggesting ResT may play a larger role in replication than previously thought. Yesforeve
Physical Activity, Smoking, and Other Health-Related Behaviours in Canadians with Epilepsy: Are Behaviours Changing Over Time?
No full textPrevious studies have indicated that people with epilepsy (PWE) are more likely to smoke cigarettes and less likely to engage in physical activity or consume fruits and vegetables. It is unknown whether improvements have occurred following updated guidelines and public health interventions. This project aimed to explore patterns of health related behaviors (HRBs) such as smoking and physical activity in Canadians with epilepsy and examine whether behaviors have changed over time using data from a series of five national population-based surveys spanning from 2001 to 2011. In total, 522,722 Canadians were included in the dataset, including 3,220 PWE. The proportion of PWE who did not participate in any physical activity decreased over time (2001=17.2%, 2010/2011=8.5%), as did the proportion of PWE who currently smoked (2001=32.3%, 2010/2011=18.0%). However, fruit and vegetable consumption was consistently inadequate among PWE. Physicians should continue to counsel epilepsy patients on the importance of healthy lifestyle choices.indefinit
Regulation of Aquaporin 3 Expression in Intestinal Epithelial Cells by Tumour Necrosis Factor Alpha and Interferon Gamma
No full textElectrolyte and water balance are tightly regulated by the host in the gastrointestinal tract. Inflammatory bowel diseases, namely Crohn’s disease and ulcerative colitis, are associated with decreased absorption and impaired secretion, leading to impaired barrier function characterized by the development of diarrhea. Aquaporin (AQP) 3 is highly expressed in epithelial cells of the gastrointestinal tract and may be involved in the transcellular transport of water across the intestinal epithelium. We hypothesized that AQP3 expression and localization in intestinal epithelial cells are altered in intestinal inflammation and that these changes are driven by the inflammatory cytokines tumour necrosis factor (TNF) α and interferon (IFN) γ. Our studies revealed that AQP3 protein is expressed in the basolateral membrane of both human and mouse colonic epithelial cells. In mice, AQP3 was downregulated in distal colonic epithelial cells early in colitis. These changes could be reproduced in HT-29 adenocarcinoma cells treated with two cytokines involved in intestinal inflammation. Specifically, TNFα downregulated AQP3 mRNA transcription through both MEK/ERK and NF-κB signalling, acting on the transcription factor specificity protein (Sp) 3 found bound to the AQP3 promoter. In contrast, IFNγ downregulated AQP3 mRNA transcription independent of JAK2 signalling, but required signal transducer and activator of transcription (STAT) 1, whereas STAT3 appeared to be involved in the constitutive repression of AQP3 expression. Mechanisms regulating AQP3 transcription are similar to those regulating numerous ion channels involved in absorption and secretion, suggesting a common mechanism by which both ion and water transport are altered in inflammation.indefinit