Thrombosis is a vascular pathological process which frequently affects the veins of the lower limbs, and embolisation of thrombotic material is common. Thromboembolic disease is a common cause of death in Western societies, predominantly affecting the elderly. Numerous risk factors and co-morbidities have been identified. Safe and effective means of prophylaxis are available but are underutilised. Anticoagulant drugs are very effective in preventing thromboembolic disease, but their effects on the evolution of the thrombotic process remain poorly documented. These drugs are difficult to use, and treatment errors and treatment failures are common. The factors which determine the embolisation of deep vein thrombosis are poorly understood. When such embolisation occurs it is usually asymptomatic. Symptomatic pulmonary embolism presents in 3 general ways-pleuritic pain, shortness of breath, or collapse. Tachypnea is the commonest sign. Tests which are available to assist in the diagnosis of thromboembolic disease include the ventilation perfusion lung scan, ultrasound of the lower limbs, pulmonary angiography and echocardiography. The commonest investigation requested in this context is the lung scan. Although the results are often inconclusive, this is frequently the only specific investigation which is performed. The accurate interpretation of lung scans requires consideration of the pretest probability of pulmonary embolism. The D-dimer assay is another test which may be useful. The finding of a normal D-dimer level substantially reduces the probability of thromboembolic disease and may render a lung scan unnecessary. / Subscription resource available via Digital Dissertations only.

Doctor of Philosophy / Department of Sociology, Anthropology, and Social Work / Robert Schaeffer / World-system theorist Immanuel Wallerstein made two theoretical assertions in Historical Capitalism that (a) significant inequalities in the “margin of safety against…endemic dangers and erratic violence” for people in different zones of the world economy persisted over long periods of time and (b) that the “margin of safety” for people in the periphery has actually deteriorated. This study set out to test this theory by examining mortality data for countries in different zones of the world-economy. It identified a set of health-related proxies for “endemic dangers and erratic violence”, infectious diseases (malaria, polio, tuberculosis, and influenza), chronic diseases (cancer, diabetes, and cardiovascular), erratic violence (homicide, suicide, and motor vehicle accidents), and also infant mortality and life expectancy for women and men. It gathered data from the United Nations Statistical Division’s Demographic Yearbook for a select sample of countries in different zones of the world-economy (core, semiperiphery, and periphery) from 1950 to 2010, and examined how mortality from these dangers changed during this period. This study found that mortality data for infectious diseases did not provide much support for Wallerstein’s theoretical assertions. But the mortality data for chronic disease and erratic violence provided strong support for Wallerstein’s assertions. The data on life span provided some support for Wallerstein’s first assertion, but not for his second. Overall, the findings generally support Wallerstein’s theories and suggest ways that health-related inequalities might be addressed.

Master of Science / Department of Kinesiology / Thomas J. Barstow / Background and Aim: Long-term microgravity exposure, via spaceflight or -6° head-down tilt bedrest, has been shown to produce significant cardiovascular deconditioning and decreases in exercise performance. However, there is little known about how acute microgravity exposure influences the cardiovascular system’s ability to adjust to increases in physical work. Therefore, the aim of this study was to compare cardiovascular and exercise performance during acute upright, supine and -6° head-down tilt positions. Methods: Seven healthy inactive men performed maximal cycle exercise (VO2peak) tests in the upright, supine, and -6° head-down tilt on separate days. Oxygen consumption and heart rate were measured continuously throughout the testing procedures. Cardiac output (acetylene exhalation technique) was measured periodically and interpolated to the 100-watt work rate. Stroke volume was calculated from cardiac output and heart rate data. Results: Peak oxygen uptake and heart rate were significantly decreased in the supine and -6° head-down tilt positions compared to the upright (VO2peak 2.01±0.46, 2.01±0.51 versus 2.32±0.61 L/min respectively; peak heart rate 161±13, 160±14 versus 172±11 bmp). However, cardiac output at 100-watts was similar in all three-exercise positions. Calculated stroke volume at 100-watts was significantly higher in the -6° head-down tilt position compared to the upright position (76.6±4.7 versus 71.2±4.5, ml). Conclusion: These results suggest that exercise capacity is immediately decreased upon exposure to a microgravity environment, prior to any cardiovascular deconditioning. Therefore, an astronaut’s exercise performance should be evaluated with exercise tests in the -6° head-down tilt position prior to space flight in order to establish a baseline response.

Master of Science / Department of Anatomy and Physiology / Deryl L. Troyer / There is renewed interest in magnetic hyperthermia as a treatment modality for cancer, especially when it is combined with other more traditional therapeutic approaches, such as the co-delivery of anticancer drugs or photodynamic therapy. The influence of bimagnetic nanoparticles (MNPs) combined with short external alternating magnetic field (AMF) exposure on the growth of subcutaneous mouse melanomas (B16-F10) was evaluated. Bimagnetic Fe/Fe3O4 core/shell nanoparticles were designed for cancer targeting after intratumoral or intravenous administration. Their inorganic center was protected against rapid biocorrosion by organic dopamine-oligoethylene glycol ligands. TCPP (4-tetracarboxyphenyl porphyrin) units were attached to the dopamine-oligoethylene glycol ligands. The magnetic hyperthermia results obtained after intratumoral injection indicated that micromolar concentrations of iron given within the modified core-shell Fe/Fe3O4 nanoparticles caused a significant anti-tumor effect on murine B16-F10 melanoma with three short 10-minute AMF exposures. There is a decrease in tumor size after intravenous administration of the MNPs followed by three consecutive days of AMF exposure. These results indicate that intratumoral administration of surface-modified MNPs can attenuate mouse melanoma after AMF exposure. Moreover, intravenous administration of these MNPs followed by AMF exposure attenuates melanomas, indicating that adequate amounts of TCPP-labeled stealth Fe/Fe3O4 nanoparticles can accumulate in murine melanoma after systemic delivery to allow effective magnetic hyperthermic therapy in a rodent tumor mode.

A population based cross-sectional time series analysis was conducted using three Ontario administrative databases, to assess trends over time in the surgical management of kidney stone disease. All kidney stone treatments performed with extracorporeal shockwave lithotripsy (SWL), ureteroscopy (URS) and percutaneous nephrolithotomy between July 1, 1991 and December 31, 2010, were included. Time series modeling with exponential smoothing and autoregressive integrated moving average models demonstrated a significant increase in the utilization of URS over time (23.69% to 59.98%, p<0.0001), with a reciprocal significant decrease in the utilization of SWL (68.77% to 33.36%, p<0.0001). As a result of this shift in treatment paradigm, time series modeling also demonstrated an associated significant decrease in the need for ancillary treatment over time (22.12% to 16.01%, p<0.0001) and a significant increase in the need for hospital readmission (8.01% to 10.85%, p<0.0001) or emergency room visit (7.58% to 9.95%, p=0.0024) within 7 days following treatment.

A population based cross-sectional time series analysis was conducted using three Ontario administrative databases, to assess trends over time in the surgical management of kidney stone disease. All kidney stone treatments performed with extracorporeal shockwave lithotripsy (SWL), ureteroscopy (URS) and percutaneous nephrolithotomy between July 1, 1991 and December 31, 2010, were included. Time series modeling with exponential smoothing and autoregressive integrated moving average models demonstrated a significant increase in the utilization of URS over time (23.69% to 59.98%, p<0.0001), with a reciprocal significant decrease in the utilization of SWL (68.77% to 33.36%, p<0.0001). As a result of this shift in treatment paradigm, time series modeling also demonstrated an associated significant decrease in the need for ancillary treatment over time (22.12% to 16.01%, p<0.0001) and a significant increase in the need for hospital readmission (8.01% to 10.85%, p<0.0001) or emergency room visit (7.58% to 9.95%, p=0.0024) within 7 days following treatment.

Human immunodeficiency virus infection is a chronic condition causing significant changes in the immune system, which are reflected in the altered gene expression patterns of the immune cells. By studying these patterns through gene expression profiling it is possible to describe not only the current states the cells are in, but also to extrapolate the proximal signals that resulted in the observed patterns. In the studies described herein, we have applied this approach to better understand the alterations in the immune function that occur in HIV infection. First, we have obtained transcriptional profiles of CD4+ and CD8+ T cells from patients in early infection, in chronic infection, and in non-progressive infection, and we compared these profiles to each other and to the profiles from uninfected donors. The analyses of the profiles revealed no discernable changes in the T cells of the non-progressive patients when compared to the uninfected individuals. On the other hand, T cells from patients with progressive infection, both early and late, showed patterns characteristic of type I interferon (IFN) exposure. We next examined experimentally the possible proximal causes of the observed transcriptional profiles. We analyzed the gene expression patterns induced by TGFβ, 13 type I interferons, as well as recombinant HIV Tat protein, in T cells and peripheral blood mononuclear cells. The TGFβ responses were inconsistent with the transcriptional profiles seen in HIV-infected patients, whereas both type I IFNs and HIV Tat induced genes in patterns consistent with those seen in patients. In fact, the thirteen IFN-induced patterns were indistinguishable from each other. Tat treatments induced interferon-stimulated genes (ISGs) as well as other genes and the response was not dependent on the presence of plasmacytoid dendritic cells (pDCs), suggesting monocytes as the possible source of the interferon response. In the last study, we examined the responses of plasmacytoid dendritic cells (pDCs) to HIV and other stimuli in healthy and HIV-infected subjects. We observed induction of IFN genes in pDCs of all subjects in response to influenza virus and TLR7 agonist imiquimod, but not to HIV virus. In summary, HIV infection results in chronic induction of type I IFN response in cells of the immune system. The source of this response is likely to be type I IFNs produced by monocytes/macrophages rather than plasmacytoid cells. The monocytic production of type I IFN may be a Tat-dependent response.

This dissertation involved linking a clinical cystic fibrosis (CF) data registry with administrative databases to evaluate clinical, demographic, and geographical predictors of hospitalization in CF patients living in Ontario over a 10 year period. In addition, this work assessed the ability of administrative data to identify individuals with CF using the clinical registry as the reference standard. Sex was an independent predictor of hospitalization rates for individuals with CF. Females had a significantly higher hospitalization rate compared to males even after adjusting for important clinical factors suggesting that this finding is not simply due to worse CF disease. In those between 7 and 19 years of age, the adjusted hospitalization rate was 38% higher in females (rate ratio[RR] 1.38, 95% confidence interval [CI] 1.11-1.73). Similarly in those over the age of 19, females had a 30% higher hospitalization rate compared to males (RR 1.30, 95% CI 1.06-1.59). Other significant predictors associated with higher hospitalization rates in both age groups were lower lung function, worse nutritional status, pancreatic insufficiency, and the presence of CF-related diabetes. The presence of Burkholderia cepacia complex in the sputum was a significant predictor in those over the age of 19 years (RR 1.54, 95% CI 1.26-1.89). Distance to CF centre, community size and socioeconomic status were not significant predictors of hospitalization rates in either age group. There was no significant trend in hospitalization rates over time once rates were adjusted for markers of disease severity (p=0.08). Comparing administrative data with the CF registry data, administrative data captured hospitalizations more comprehensively. Despite CF being a specific diagnosis, health administrative databases alone were insufficient to reliably and accurately identify individuals with CF unless they had been hospitalized. The reason for the gender disparity seen within this dissertation is likely multifactorial. There may be differences in outpatient management between the sexes, hormonal influences may modulate disease severity causing higher hospitalization rates, and patient and provider-level influences may affect the decision to hospitalize a patient. Further research is needed in this area to elucidate the factors contributing to this gender gap.

Acute Respiratory Distress Syndrome (ARDS) following hemorrhagic shock/resuscitation (S/R) is an important contributor to late morbidity and mortality in trauma patients. S/R promotes ARDS by inducing oxidative stress that primes cells of the innate immune system for excessive responsiveness to small inflammatory stimuli, termed the “twohit” hypothesis. Activated alveolar macrophages (AM) play a central role and when recovered from S/R animals exhibit an exaggerated responsiveness to lipopolysaccharide (LPS) with increased activation of the proinflammatory transcription factor NF-κB, and augmented expression of cytokines. LPS triggers AM signalling through Toll like receptor 4 (TLR4), which resides in plasma membrane lipid rafts. The objective of this work is to define cellular mechanisms of macrophage priming by oxidative stress following shock resuscitation. The main hypothesis investigated is that altered cellular distribution of TLR4 can lead to macrophage priming and antioxidant resuscitation strategies can diminish these effects. AM of rodents, exposed in vivo to oxidant stress following S/R, increase their surface levels of TLR4, which in turn results in augmented NF-κB translocation in response to small doses of LPS. Furthermore, in vitro H2O2 treatment of RAW 264.7 macrophages results in similar TLR4 surface translocation. Depletion of intracellular calcium, disruption of the cytoskeleton or inhibition of the Src kinases prevents the H2O2-induced TLR4 translocation, suggesting the involvement of receptor exocytosis. Further, fluorescent resonance energy iii transfer between TLR4 and lipid rafts as well as biochemical raft analysis demonstrated that oxidative stress redistributes TLR4 to surface lipid rafts. Preventing the oxidant-induced movement of TLR4 to lipid rafts using methyl-ß-cyclodextrin precluded the increased responsiveness of cells to LPS after H2O2 treatment. Further, AM priming by oxidative stress can be diminished by early exposure to resuscitation regimens with direct or indirect systemic antioxidant effects, such as 25% albumin, N-acetylcysteine and hypertonic saline. Hyperosmolarity was found to modulate AM TLR4 gene and protein expression. Collectively, these studies suggest a novel mechanism whereby oxidative stress might prime the responsiveness of cells of the innate immune system. Targeting the TLR4 signalling pathway early during shock resuscitation may represent an anti-inflammatory strategy able to ameliorate late morbidity and mortality following S/R.

The family of human kallikrein-related peptidases (KLKs) numbers 15 serine proteinases implicated in tumour progression. Despite the wide tissue distribution of KLKs and the numerous reports of their differential expression in pathological settings, the signalling mechanism(s) whereby these enzymes regulate tissue function are not yet known. Further, knowledge of the levels of their activity, as well as of their potential endogenous targets, has only been extracted from in vitro studies and cell culture systems. We hypothesized that KLKs can trigger tumour signalling via proteinase-activated receptors (PARs), a family of G-protein-coupled receptors. To test our hypothesis, we evaluated the ability of KLKs 5, 6, and 14: to activate or prevent signalling via PARs 1, 2, and 4 in cells and tissues expressing these receptors. Further, we used a novel activity-based probe approach, coupled with conventional immunoassay (ELISA), to determine the abundance of active KLK6 relative to total immunoreactive KLK6 in cancer-related biological fluids. We concluded that KLKs can regulate multiple signalling pathways triggered by PARs 1, 2, and 4, resulting in calcium release, platelet aggregation and vascular relaxation, and they can cause murine inflammation. Further, our activity-based ELISA demonstrated the presence of active KLK6 in ovarian cancer ascites fluids and cancer cell supernatants. We, therefore, suggest that tumours can produce active KLKs, which can potentially control tumour behaviour by regulating PAR activity.