The act of raising the heel up is an essential portion of the gait cycle in humans, comprising the third rocker in the gait cycle. This act further demands specific motions from the hindfoot, and the surrounding structures. These motions have been previously studied and are reasonably well understood. End-stage osteoarthritis of the ankle (or ESOA) has been theorized to affect not only the ankle joint, but the same joints required for heel rise. (i.e. - hindfoot, lower leg, and foot) In the present research, the powerful effect that ESOA has on the lower leg, hindfoot and forefoot biomechanical relationship was demonstrated as significantly different from that of healthy age and sex-matched controls. This has implications not only for further research, but potentially treatment as well.

The act of raising the heel up is an essential portion of the gait cycle in humans, comprising the third rocker in the gait cycle. This act further demands specific motions from the hindfoot, and the surrounding structures. These motions have been previously studied and are reasonably well understood. End-stage osteoarthritis of the ankle (or ESOA) has been theorized to affect not only the ankle joint, but the same joints required for heel rise. (i.e. - hindfoot, lower leg, and foot) In the present research, the powerful effect that ESOA has on the lower leg, hindfoot and forefoot biomechanical relationship was demonstrated as significantly different from that of healthy age and sex-matched controls. This has implications not only for further research, but potentially treatment as well.

Hypothesis: Trimethoprim promotes wound healing, decreases lesion counts and improves quality of life of recessive dystrophic epidermolysis bullosa (RDEB) patients. Objectives: Assess feasibility of conducting a large randomized clinical trial. Determine efficacy of trimethoprim in healing of chronic wounds, decreasing lesion counts and improving quality of life of RDEB patients. Methods: Prospective, randomized, double-blinded, placebo-controlled, cross-over pilot study. Results: Ten patients enrolled in the trial, 7 completed both study periods. Despite showing that all patients improved on trimethoprim and that there was a 41% difference in affected area percent change favoring trimethoprim, the cross-over analysis did not show a significant difference between the drug and placebo (p=0.08). Secondary outcome measures did not achieve statistical significance. Limitations: Small sample size, large variation in wound size and unaccounted confounders. Conclusions: Although patients experienced improvement while on trimethoprim, no statistical significant change was showed when compared to placebo.

Anthracycline- and taxane-based regimens have been the mainstay in treating breast cancer patients using chemotherapy. Yet, the genetic make-up of patients and their tumors may have a strong impact on tumor sensitivity to these agents and to treatment outcome. This study represents a new paradigm assimilating bioinformatic tools with in vitro model systems to discover novel genetic variations that may be associated with chemotherapy response in breast cancer. This innovative paradigm integrates drug response data for the NCI60 cell line panel with genome-wide Affymetrix SNP data in order to identify genetic variations associated with drug resistance. This genome wide association study has led to the discovery of 59 candidate loci that may play critical roles in breast tumor sensitivity to doxorubicin and paclitaxel. 16 of them were mapped within well-characterized genes (three related to doxorubicin and 13 to paclitaxel). Further in silico characterization and in vitro functional analysis validated their differential expression in resistant cancer cell lines treated with the drug of interest (over-expression of RORA and DSG1, and under-expression of FRMD6, SGCD, SNTG1, LPHN2 and DCT). Interestingly, three and six genes associated with doxorubicin and paclitaxel resistance, respectively, are involved in the apoptotic process in cells. A constructed interactome suggested that there is cross-talk at the Nrf-2 oxidative stress pathway between genes associated with resistance to doxorubicin and paclitaxel. This unique GWA approach serves as a proof-of-principle study and systematically investigates targets responsible for variable response to chemotherapy in breast tumor cells and possibly the tumors of breast cancer patients. Overall, the model discovered novel candidate genes that have not been previously associated with doxorubicin and paclitaxel cytotoxicity. Future studies will be directed at illustrating a causative relationship between the observed genomic changes and drug resistance in breast cancer patients undergoing doxorubicin and paclitaxel chemotherapy.

HSV-2 may have adverse consequences in HIV. I evaluated the impact of HSV-2 co-infection on (highly active antiretroviral therapy)-untreated HIV infection in a systematic review of observational studies (study 1) and a retrospective cohort (study 2). I further evaluated whether HSV reactivation rates in co-infected persons differ by use of suppressive cART (study 3). Study 1 found modest evidence that HSV-2 seropositivity may be associated with accelerated progression to opportunistic infection or clinical AIDS, but not with increased HIV viral load. Some evidence suggests that HSV-2 disease activity is associated with increased HIV viral load and decreased CD4 counts. Study 2 compared rates of CD4 count change by HSV-2 status (Focus HerpeSelect ELISA) among 218 patients with a past period of ART-untreated follow-up using mixed linear regression models. No significant difference in the rate of CD4 count change was observed in HSV-2 seropositives at +13.6 cells/mm3/year (p=0.12) in univariate analysis, and -4.5 cells/mm3/year (p=0.68) in analysis adjusted for sex, HSV-1, oral and genital HSV symptoms, immigrant status, and immigrant*time interaction. These findings support the need for carefully designed and executed studies of HSV-2 suppression as an adjunctive management strategy for HIV disease, but raise questions regarding the exact mechanism of negative synergy between these viruses and the relative importance of HSV-2 latency and replication in driving these effects. In Study 3, 44 cART-naïve and 41 treated (HIV RNA<50 copies/mL) HIV+ adults with HSV-1 and/or 2 co-infection collected oral, genital and anal swabs daily for 28 days. Negative binomial models were used to quantify the relationship between cART and HSV shedding (Roche LightCycler HSV1/2). Overall HSV shedding was low, at a median (IQR) of 3.6% (0, 14.3%) of days. No relationship was seen between cART and HSV-1 or 2 shedding in univariate (RR=1.55, 95%CI=0.83,2.87) or multivariate analysis adjusted for sex, baseline CD4, recent immigrant status, and time since HIV diagnosis (aRR=1.05, 95%CI=0.43,2.58). Null results were also observed for HSV-1 and HSV-2 considered separately. That HSV shedding persists despite cART suggests that trials of anti-HSV drugs for improving HIV outcomes may be warranted in such patients.

Hypothesis: Trimethoprim promotes wound healing, decreases lesion counts and improves quality of life of recessive dystrophic epidermolysis bullosa (RDEB) patients. Objectives: Assess feasibility of conducting a large randomized clinical trial. Determine efficacy of trimethoprim in healing of chronic wounds, decreasing lesion counts and improving quality of life of RDEB patients. Methods: Prospective, randomized, double-blinded, placebo-controlled, cross-over pilot study. Results: Ten patients enrolled in the trial, 7 completed both study periods. Despite showing that all patients improved on trimethoprim and that there was a 41% difference in affected area percent change favoring trimethoprim, the cross-over analysis did not show a significant difference between the drug and placebo (p=0.08). Secondary outcome measures did not achieve statistical significance. Limitations: Small sample size, large variation in wound size and unaccounted confounders. Conclusions: Although patients experienced improvement while on trimethoprim, no statistical significant change was showed when compared to placebo.

Colorectal cancer (CRC) is common in Ontario. This study described the processes of care following CRC resection, and identified CRC relapse from administrative data. Methods: CRC patients aged 18-80 from 1996-2001 with a colorectal resection were identified from the Ontario Cancer Registry. Linked discharge abstracts and physician billings were examined for physician visits, body imaging and endoscopy over the 5 year follow-up period. Administrative codes suggesting disease relapse were compared with patient charts. Results: Overall, 12,804 patients were identified and 8,804 had no evidence of relapse. Most (96.2%) patients had general practitioner follow-up, while 49.3% had medical oncology and 80.4% had general surgery follow-up. Greater than 90% of patients received endoscopy, while only 68.7% of patients received body imaging. Detecting disease relapse was 87.5% sensitive and 93.0% specific. Conclusions: There is potential for improving post-resectional follow-up in CRC patients. It is possible to detect relapse through administrative databases.

Psoriatic Arthritis (PsA) is an inflammatory arthritis associated with psoriasis that leads to progressive joint damage. Genetic variants in the Major Histocompatibility Complex (MHC) region on human chromosome 6p, especially Human Leucocyte Antigen (HLA), are the most important genetic risk variants associated with susceptibility to PsA. I aimed to investigate the heritability of PsA and to determine the association between HLA polymorphisms with susceptibility and severity of PsA. I first validated the new CASPAR classification criteria for PsA in patients in with both early and established disease. Subsequently, I demonstrated that PsA as defined by the CASPAR criteria has a high recurrence risk ratio. In a large case-control and family-based association study, I demonstrated that the class I HLA alleles, HLA-C*12/B*38, -B*27 and -C*06/B*57 are associated with increased susceptibility to PsA. HLA class I molecules biologically interact with Killer-cell Immunoglobulin-like Receptors (KIR) on Natural Killer (NK) to influence immune response. I demonstrated that KIR2DS2 and HLA C group 2 and HLA-B Bw4 were associated with PsA susceptibility. Further analyses of PsA cases with Type II psoriasis and with dactylitis suggested that HLA-C*02, -B*27, -B*38 and KIR2DS2 may be markers of musculoskeletal manifestations of PsA. Furthermore, using longitudinal data, I demonstrated that HLA-B*39, -B*27, -A*02 and KIR3DS1 are associated with peripheral joint damage progression whereas the alleles –DQB1*0604, -C*04 and –B*60 are associated with less damage progression. HLA-C*02, -C*12, -DQB1*0609 and KIR2DS1 are associated with higher risk of sacroiliitis, and HLA-B*27 with syndesmophytes. HLA-A*29 was associated with reduced risk of development of both sacroiliitis and syndesmophytes. These studies indicate that HLA alleles and KIR genes are important in PsA susceptibility and severity and suggest that CD8+ T cells and NK cells that modulate the innate and adaptive immune response play an important role in the susceptibility and severity of PsA.

Spinal cord injury (SCI) is a debilitating condition accompanied by motor and sensory deficits and a reduced quality of life. Current treatment options are limited and are associated with variable efficacy and a risk of adverse effects. The pathophysiology of SCI is initiated by a primary mechanical insult to the spinal cord, followed by a complex series of deleterious events known as secondary injury. Secondary injury processes include free radical formation, glutamate excitotoxicity, inflammation and cell death. Apoptotic cell death in particular plays a key role in the secondary injury processes and exacerbates tissue degradation and loss of function. The role of Fas-mediated apoptosis in SCI pathophysiology is poorly defined in the literature to date. Correlative evidence suggests that this form of cell death is delayed and occurs in white matter adjacent to sites of primary damage. The cellular and temporal mechanisms of Fas-mediated apoptosis following experimental SCI were evaluated using a clinically relevant clip compression SCI model in the rat. Furthermore, therapeutic manipulation of Fas activation using a soluble form of the Fas receptor (sFasR) was carried out to establish the efficacy and clinical relevance of targeting this aspect of secondary injury. This work shows that Fas-mediated apoptosis is an important contributor to secondary SCI pathology. Oligodendrocytes are targeted by this form of cell death in a delayed fashion post-injury, providing an opportunity for therapeutic intervention. Intrathecal administration of sFasR following SCI reduced post-traumatic apoptosis, improved cell survival, enhanced tissue preservation and resulted in an improved motor recovery. Administration of sFasR was effectively delayed by up to 24 hours post-injury, however a shorter delay of 8 hours post-injury was most efficacious. A surprising result emerged from this work. Delayed intrathecal administration of IgG following SCI showed significant efficacy in both cellular and tissue level outcomes, as well as at the functional level. Fas-mediated apoptosis is an important aspect of secondary SCI pathophysiology and is an attractive therapeutic target. The beneficial outcomes of manipulating Fas activation using sFasR provide further evidence for this. Future work will refine this treatment strategy, bringing it into the SCI patient population.

Introduction: Currently, there are no objective techniques to assess burn depth. An early assessment of burn depth would enable accurate management decisions, which would improve patient outcomes. Near infrared (NIR) technology has shown promise as a non-invasive monitor of oxygenation and perfusion, and its potential to assess the depth of burn injuries has been investigated clinically over the past five years. The purpose of the thesis was to determine the capacity of NIR technology to differentiate acute thermal injuries. Methods: Burn sites (n=5) and control sites (n=5) were created on the dorsum of sixteen animals with brass rods held at constant pressure and heated to 100°C and 37.5°C respectively. NIR data was collected from the burns and control sites pre-burn, immediately post-burn, and 1, 12, 24, 36, 48 and 96 hours after the burn injury. Biopsies of the burn and control sites were acquired at each time point and used to confirm the depth of injury. NIR data was processed for the content of water, oxy-, deoxy- and methemoglobin. Results: Oxyhemoglobin and total hemoglobin decreased as burn depth increased. The proportion of oxy- and deoxyhemoglobin to total hemoglobin showed that the ratio of oxy- to deoxyhemoglobin decreased as burn injury increased. Methemoglobin levels as a ratio of total hemoglobin also showed that as the severity of injury increased the proportion of methemoglobin also increased. Finally, superficial partial thickness injuries (3 s and 12 s) showed early peak levels of water, which rapidly declined towards baseline. The deep partial thickness injuries (20 s and 30 s) do not experience peak levels and retain water over the course of the experiment. The full thickness injuries water levels remain close or below baseline levels throughout the experiment. Conclusion: NIR spectroscopy could distinguish burn depth using water, oxy-, met- and total hemoglobin as separate entities. The presence of methemoglobin in the burn wounds is a novel finding that has not been described previously in burn literature.