Introduction: This study describes the patterns of use and processes of care following colonic stent insertion for patients with colorectal cancer (CRC) in clinical practice. Methods: Ontario residents who had a colonic stent placed for CRC between 2000–2009 were identified using linked administrative databases. Baseline patient, physician, and institutional characteristics were extracted. The cohort was followed for death and health services utilization post-stent. Results: Two hundred twenty-five patients were identified. Median overall survival post-stent insertion was 199 days (interquartile range [IQR] 153-282). Eighty-five (38%) patients required a subsequent intervention (abdominal surgery, restenting, and/or dilatation). Median intervention-free survival was 75 days (IQR 59-91). Following stent insertion, the average rate of ER visits was 2.4 visits per person-year of follow up (95% CI, 2.2-2.7) and the overall average days spent in hospital was 19 inpatient days per person-year (95% CI, 18-19). Conclusions: In clinical practice, many patients required another intervention shortly after stent insertion; however, the rate of post-stent ER visits and inpatient hospital days was low.

New neurons are generated throughout adulthood in the dentate gyrus of the hippocampus. The aim of the current study was to address whether differences in the morphological complexity of adult-born granule cells affect their integration into existing dentate gyrus circuitry. To selectively label proliferating cells, we injected a CAG-retrovirus into the dentate gyrus of mice. Either 10, 20, 40, or 80 days following viral infection, mice were injected with pentylenetetrazol (PTZ) to induce hippocampal activation, and expression of the immediate early gene c-fos was used as a marker of activated neurons. We then compared morphological features of neurons across age groups and between Fos+ and Fos- neurons within each age group. We found that dendritic length and branch number increased from 10 to 20 days post infection. Unexpectedly, we also found that dendritic length and branch number decreased from 20 to 40 days post infection, suggesting that the maturation of adult-generated neurons is associated with an active pruning process. Furthermore, we found no significant difference in morphological complexity between Fos+ and Fos- neurons, suggesting that dendritic morphology does not influence integration into dentate gyrus circuitry.

Revelations of kickbacks from surgical device manufacturers to surgeons raise the question whether surgeons can continue to collaborate with industry and maintain public trust. Using qualitative and quantitative methodology, this thesis explores surgical patients’ views on financial relationships between surgeons and manufacturers and patients’ recommendations for managing these conflicts of interest. A majority of patients approve of surgeon’s relationships with manufacturers that can benefit patients but disapprove of those that primarily benefit the surgeon and the manufacturer. The majority of patients do not endorse disclosure as a sole method of managing these relationships. The majority of patients trust the surgical profession to self-regulate and favour professional oversight rather than by government to ensure financial relationships between surgeons and manufacturers are appropriate. My data supports my argument that there should be professional oversight of financial relationships between surgeons and manufacturers, which may allow continued collaboration with manufacturers while maintaining public trust.

BACKGROUND: Differences in disease-modifying therapy (DMT) prescribing patterns between different groups of neurologists have not been explored. HYPOTHESIS: MS-specialist neurologists use a broader range of DMTs in contrast to generalist neurologists who preferentially prescribe Avonex. METHODS: Ontario neurologist demographic and geographical characteristics were linked to 2009 DMT prescription data. Lorenz curves and Gini coefficients were constructed to examine prescribing patterns; separating neurologist characteristics dichotomously and separating Avonex from the other DMTs. Gini Coefficients were compared using jack-knife statistical techniques to derive 95% confidence intervals. RESULTS: Prescriptions are highly concentrated with 12% of Ontario neurologists prescribing 80% of DMTs. High-volume prescribers show a broader range of DMT use while low-volume prescribers tend to use a particular DMT. CONCLUSIONS: The majority of DMTs are prescribed by a small subset of neurologists. High-volume prescribers show more variability in DMT use while low-volume prescribers tend to individually focus on a narrower range of DMTs.

The ability of articular cartilage to self-repair after injury is limited due to the nature of the tissue. Biological repair is a promising treatment for cartilage injuries but success is limited by the ability to integrate with native cartilage. An in vitro model can be developed to investigate factors that regulate cartilage repair. A tissue engineered cartilage construct was placed into a host bovine osteochondral explant and cultured for 4 and 8 weeks. This same construct was cultured under stimulated and unstimulated conditions for 2 and 4 weeks. Autologous osteochondral implants served as controls. Integration was evaluated histologically, biochemically, biomechanically and for changes in gene expression. The tissue-engineered implants integrated over time whereas the autologous implants did not. Mechanical stimulation and prolonged incubation improved integration between implant and host tissue. An in vitro model of repair-native cartilage integration has been developed which is suitable for further study of tissue integration.

Lung transplantation is a life-saving therapy for patients suffering from end-stage lung disease; however, the majority of donor lungs are injured and attempts to transplant them results in a high risk of primary graft dysfunction in the recipient, a type of severe acute lung injury. Previously, a novel method of lung preservation known as ex vivo lung perfusion (EVLP) has been developed in which donor lungs are continuously perfused and ventilated at normothermia using a protective strategy. Donor lungs have been shown to tolerate at least 12 h of preservation in this manner without the accrual of injury. Hence, EVLP could act as a platform on which injured donor lungs could potentially be evaluated and repaired. To explore this concept, we utilized interleukin-10 (IL-10), an anti-inflammatory cytokine, as a prototypical drug for ex vivo delivery. Because IL-10 protein has a prolonged half-life during EVLP, we delivered recombinant IL-10 by the intravascular and intratracheal routes to clinically-rejected injured human lungs. Intratracheal delivery resulted in elevated levels of IL-10 in both tissue and perfusate whereas intravascular delivery resulted in elevated levels of IL-10 only in the perfusate over 12 h of EVLP. There was, however, no beneficial effect to either lung function or lung inflammation. This was thought to be a result of intratracheally delivered IL-10 leaking out into the perfusate where it may not be biologically active. Constant IL-10 production within the lung tissue could be achieved using a gene therapy approach. Thus, we subsequently explored the delivery of IL-10 by adenoviral gene therapy during EVLP. Ex vivo administered intratracheal adenoviral gene therapy could increase transgene protein levels within the lung. More importantly, it did so with less vector-associated inflammation when compared to in vivo delivery of adenoviral gene therapy. Having explored drug delivery, we sought to develop a large animal injury model on which to test ex vivo therapies. Given that the majority of organ donors are brain dead and therefore exposed to the injurious sequelae resulting from brain death, we developed a brain-death injury model in pig. Use of EVLP as a platform for repair necessitates an accurate recognition of both lung injury and lung improvement during EVLP. Thus, we utilized this injury model to explore the profile of physiological parameters when an injured lung is perfused during EVLP. Because of the alteration of the PO2 to oxygen content relationship of an acellular perfusate, we found that PaO2 changes are less dramatic than in the in vivo situation. However, as injured lungs begin to become edematous, the mechanical effects on the lung by the increased water content can be measured by corresponding falls in compliance and increases in airway pressure. Overall, use of EVLP demonstrates promise for reducing the organ shortage currently prevalent in clinical lung transplantation. Improved evaluation will instill confidence in transplant clinicians to transplant previously questionable organs. Lungs which prove to be injured during evaluation can potentially be repaired using IL-10 therapy as explored herein or with other therapies using the delivery methods described.

Primarily expressed by trophoblast cells, human leukocyte antigen-G (HLA-G) plays an essential role in maintaining maternal-fetal immune tolerance. Having previously been detected following heart transplantation, we sought to establish the value of HLA-G in identifying freedom from moderate or severe rejection post-heart transplant, and the capability of its expression in vitro. After assessing myocardial HLA-G expression through immunohistochemistry, we demonstrated that it was significantly more prevalent in non-rejecting than rejecting heart transplant recipients. Utilizing vascular endothelial and smooth muscle cell culture models, we also determined that while HLA-G expression remains tightly regulated, its expression in vitro can be induced following progesterone treatment in a dose-dependent manner. Hence, HLA-G may reliably identify patients with a low immunological risk of developing subsequent clinically significant rejection post-heart transplant. Furthermore, HLA-G expression can be induced in cultured endothelial and smooth muscle cells, which might represent a strategy to protect against allograft rejection and vasculopathy.

Objective: To determine if inhaled Hypertonic Saline (7%) improves the Lung Clearance Index in paediatric Cystic Fibrosis patients with FEV1 ≥80% predicted. Methods: In a blinded crossover trial, twenty CF patients received 4 weeks of hypertonic saline (7%) (HS) and 4 weeks of isotonic saline (0.9%) (IS) separated by a 4 week washout period. The primary endpoint was the change in LCI in the HS versus the IS treatment periods. Results: Four weeks of twice daily inhalation of HS significantly improved the LCI as compared to IS by 1.16, 95% CI [0.26, 2.05]; p=0.016. Baseline LCI before IS, 8.71+/-2.10, was not significantly different from baseline LCI before HS inhalation, 8.84+/-1.95 (p=0.73). Randomization order had no significant impact on the treatment effect (p=0.61). Conclusions: Four weeks of twice daily Hypertonic Saline (7%) inhalations improved the LCI and may be a suitable early intervention therapy for CF patients with mild disease.

Despite the decreasing incidence of peritoneal dialysis (PD) peritonitis over time, its occurrence is still associated with adverse outcomes. This thesis focuses on determining factors associated with PD peritonitis in order to facilitate identification of patients at risk. Using data collected in a multicentre Canadian database between 1996 and 2005, the study population comprised 4,247 incident PD patients, of whom 1,605 had at least one peritonitis episode. Variables independently associated with peritonitis included age [rate ratio (RR) 1.04 per decade increase, 95% CI 1.01-1.08], Black race (RR 1.37, 95% CI 1.00-1.88) and having transferred from hemodialysis (RR 1.24, 95% CI 1.11-1.38). There was an interaction between gender and diabetes (p=0.011), with an increased peritonitis risk only among female diabetics (RR 1.27, 95% CI 1.10-1.47). Choice of continuous ambulatory PD vs. automated PD did not influence peritonitis risk. These results contribute to our understanding of peritonitis risk among PD patients.

BACKGROUND: Endothelial dysfunction is a principal player in the development of allograft vasculopathy and allograft failure. The hallmark of endothelial dysfunction is impaired nitric oxide bioavailability. Recent evidence implicates endothelin-1 as an integral component of endothelial dysfunction. Immunosuppressive drugs have also been associated with the development of graft vasculopathy. We speculated that endothelin-1 results in endothelial dysfunction by impairing nitric oxide homeostasis and is a player in hypoxia and reperfusion induced vasomotor injury. In addition, we hypothesized that endothelin-1 antagonism with bosentan will limit hypoxia and reperfusion injury and prevent immunosuppressive drug injury. METHODS: We utilized human saphenous vein endothelial cells to evaluate the effects of endothelin-1, hypoxia and reperfusion on endothelial function, protein kinase modulation and cell survival. We also employed a rodent model of chronic drug therapy to assess the effect of cyclosporine and rapamycin treatment on vasomotor function. We investigated the role of nitric oxide augmentation and bosentan in preventing hypoxia and reperfusion injury and in limiting immunosuppressive drug induced vasomotor dysfunction. RESULTS: Elevated endothelin-1 levels resulted in impaired nitric oxide release and endothelial function. The effects of endothelin-1 as well as hypoxia and reperfusion were mediated by altered protein kinase B and protein kinase C activity resulting in endothelial dysfunction. We revealed that endothelin-1 is a key player in hypoxia and reperfusion induced endothelial injury. The immunosuppressive drug cyclosporine induced vasomotor dysfunction while rapamycin preserved vessel homeostasis. Vasomotor dysfunction was characterized by impaired nitric oxide and endothelin-1 homeostasis. Bosentan limited the deleterious effects of endothelin-1, hypoxic injury, reperfusion injury and cyclosporine induced vasomotor impairment. CONCLUSIONS: Our study revealed that endothelin-1 exposure as well as hypoxia and reperfusion results in endothelial dysfunction by altering specific protein kinase C isoform activities and inhibiting protein kinase B. Cyclosporine induced vasomotor dysfunction was mediated by altered nitric oxide and endothelin-1 homeostasis while rapamycin was endothelial protective. Bosentan proved to be an effective therapy at preventing endothelin-1, hypoxia and reperfusion and cyclosporine induced endothelial dysfunction. Protein kinase C modulation as well as bosentan may prove to be NOVEL therapies to prevent endothelial injury during cardiac transplantation.