Myelin and oligodendrocytes (OLGs) are the apparent targets of the immune-mediated injury that underlies the development of multiple sclerosis (M8). Recovery from M8 clinical relapses likely reflects remyelination attributed to recruitment and differentiation of oligodendrocyte progenitor cells (OPCs), rather than to new process formation by previously myelinating OLGs. Newly emerging M8-directed immuno-modulatory therapies (statins and FTY720) can readily cross the blood-brain barrier and have been shown to impact signaling pathways implicated in cytoskeletal regulation, differentiation, migration, and survival; these are cellular events presumably important for myelin integrity and remyelination. / Statins inhibit the production of cholesterol (concentrated in the myelin membrane) and isoprenoids (post-translational attachments regulating the functions of proteins such as the Rho GTPases). We showed that treatment of human and rodent-derived OPCs with lipophilic statins induced an initial process extension associated with enhanced differentiation and impaired spontaneous migration, whereas prolonged treatment induced process retraction and cell death. Rodent and human mature OLGs demonstrated similar cytoskeletal and survival responses. Chronic simvastatin therapy of mice inhibited remyelination following demyelination induced by the OLG toxin, cuprizone, attributed to a block in OPC differentiation and consequent decrease in mature OLGs. Even fully myelinated animals treated with simvastatin over the long-term demonstrated a decrease in myelin in the brain by maintaining oligodendroglial cells in the pre-OLG state and preventing continual replacement of mature OLGs. / FTY720 is an agonist of G-protein-coupled receptors S1P1, 3, 4, and 5, that are associated with distinct receptor isotype-selective activation of Rho GTPases. In human OPCs, FTY720 could induce initial S1P3/5-dependent process retraction associated with an inhibition of differentiation, and subsequent S1P1-dependent process extension. Mature OLGs showed a dose-dependent cyclic modulation of process extension and retraction was observed over time. Both human OPCs and OLGs were rescued by FTY720 under death-promoting environments. Both cell types also demonstrated a cyclic and reciprocal modulation of S1P1 and S1P5 mRNA levels, reflected in the recurring receptor isotype-dependent functional responses over time. Studies using organotypic cerebellar slice cultures demonstrated that FTY720 did not impact myelin integrity under basal conditions, yet accelerated remyelination following lysolecithin-induced demyelination. Both treatment regimens were associated with an extension of OPC and mature OLG processes. / Our observations demonstrate that drug concentrations used to modulate immune function can have differential dose and time-dependent effects on OPCs, OLGs, as well as on myelin and remyelination processes. Our findings indicate the need to monitor the effects of putative immuno-modulatory therapies on myelin-related processes in MS patients.

Whereas first line therapy for chronic obstructive pulmonary disease (COPD) usually includes a short-acting bronchodilator, there are suggestions that these agents may increase the risk of cardiac arrhythmias. In this thesis, we first assessed the risks associated with short-acting beta-agonists (SABA), long-acting beta-agonists (LABA), ipratropium bromide (IB), and methyl xanthines (MX) within a cohort of COPD patients using the health databases of Saskatchewan. In order to confirm these findings and to address some methodological issues we then replicated this analysis within a larger cohort of patients using the health databases of Quebec. / Our first study cohort consisted of 6,018 adults aged 55 and older, newly treated with bronchodilator medications. We found that new users of both IB and LABA increased the risk of arrhythmia (RR 2.39 [95% CI 1.42-4.05] and (RR 4.55 [95% CI 1.43-14.45] respectively). When the cohort was restricted by excluding subjects who had recently either been hospitalised or experienced an exacerbation, the elevated risk associated with the new use of IB persisted (RR 3.65 [95% CI 1.72-7.74]), an effect was detected with new use of MX (RR 5.17 [95% CI 1.38-19.30]), but there was insufficient power to detect an effect associated with the new use of LABA. / Due to both power issues and the limited availability of LABA within the Saskatchewan data, we replicated the analysis in a larger new-user cohort of 76,661 Quebec adults aged 67 and over. This study confirmed our earlier results, with an elevated risk of arrhythmia associated with the new use of both IB and LABA (RR 1.43 [95% CI 1.08-1.88]) and (RR 1.54 [95% CI 1.00-2.36]) respectively, as well as with new use of SABA (RR 1.28 [95% CI 1.02-1.61]). Finally, using marginal structural models, we demonstrated that both exacerbations of COPD as well as minor non-event arrhythmias were moderate time-dependent confounders within this setting. / In conclusion, we found that new use of bronchodilators in COPD, particularly IB and LABA, was associated with an increase in the risk of cardiac arrhythmias. We also demonstrated the method by which the time-dependent confounder status of specific model covariates may be evaluated.

Prostate cancer remains one of the most commonly diagnosed cancers in men and is a leading cause of cancer death. While great success has been achieved at curing early stage prostate cancer, limited success has been obtained when treating late-stage hormone independent prostate cancer. This is due to the increased propensity for skeletal and non-skeletal metastases. Thus development of novel effective therapeutic modalities against late stage prostate cancer is of critical importance. / Towards these objectives, I have focused my attention on the role of prostate secretory protein (PSP-94) which is expressed in normal individuals and in patients with early stage prostate cancer. Using our well established in vivo models of prostate cancer, I have evaluated the ability of PSP-94 and its amino acids 31-45 required (PCK3145) to decrease tumor growth and skeletal metastases in vivo and evaluated the potential mechanism(s) associated with PCK3145 anti-cancer actions. / Prostatic cancer can also develop as a result of epigenetic activation of tumor promoting genes. To evaluate the role of methylation in prostate cancer, late stage prostate cancer cells were treated with the universal methylating agent S-adenosylmethionine (SAM) and an anti-sense oligonucleotide directed against MBD2 (AS). Scrambled oligonucleotide was included as a control (S). Both SAM and MBD2-AS resulted in inhibition in uPA, MMP-2 and VEGF production leading to decreased tumor cell invasive capacity. However, SAM and MBD2-AS were not able to either further repress partially methylated genes (GSTP1) or reactivate already methylated genes (AR). Furthermore, SAM and MBD2-AS treatment resulted in significant reduction in tumor growth in vivo . Immunohistochemical and RT-PCR analyses carried out on SAM and MBD2-AS tumors revealed decreased protein and mRNA expression of uPA and MMP-2 which was partially due to increased methylation of the respective promoters even after 10 weeks post in vitro treatment as analyzed by bisulfate sequencing. In addition decreased levels of angiogenesis and tumor survival markers were observed. / Collectively, these studies are aimed at the development of novel reliable approached to diagnose and treat advanced, hormone refractory prostate cancer to reduce tumor associated morbidity and mortality.

This study has examined the effect of 3 doses of Methylphenidate (MPH) on the speed of motor and cognitive performance in children diagnosed with ADHD. Thirty children clinically diagnosed with Attention Deficit/Hyperactivity Disorder (ADHD) aged 6-12 years were recruited through the ADHD Clinic and the Severe and Disruptive Behavior Disorders Program at the Douglas Mental Health University Institute. The three doses of MPH were administered according to a double blind randomized cross-over three day trial (0.3; 0.5 0.8 mg/kg/day in a bid schedule). An improvement across all three doses of MPH on motor, cognitive and behavioural measures was observed. The improvement is significant at low doses of MPH and an increase of dose up to 0.8 mg/kg/day does not lead to further improvement of the speed of simple motor task, but might be beneficial to specific cognitive tasks. No deterioration was observed in association with higher doses of MPH.

Attention deficit hyperactivity disorder (ADHD) affects up to 10% of school-aged children and half as many adults. The core features of impulsivity, hyperactivity, and inattentiveness commonly give rise to academic underachievement, poor social relationships, and increased risk for mood and anxiety disorders. Although the relevant neurobiological mechanisms remain poorly understood, altered mesocorticolimbic dopamine (DA) transmission has been proposed. The aim of the present study was to compare striatal DA function in treatment-naive adults with ADHD vs. age- and IQ-matched controls. Two PET/[11C]raclopride scans, one with placebo and one with d-amphetamine (d-AMP; 0.3 mg/kg, p.o.), were administered to five men with ADHD and five healthy male volunteers. The ADHD group differed from controls in demonstrating significant d-AMP-induced reductions in posterior caudate (p<0.05). These results may support a proposed model of reduced DA tone leading to increased phasic signaling in ADHD.

The active form of vitamin D, 1,25-dihydroxyvitamin D3 (1,25D), is a key calcium (Ca++) regulatory hormone. It is also associated with functions unrelated to Ca++ homeostasis. Here, special attention is paid towards the anticancer properties of 1,25D. 1,25D strongly inhibits the growth of well-differentiated head and neck squamous cell carcinoma (HNSCC) derived cell lines. However, advanced, less differentiated, HNSCC cell lines (e.g. SCC4) are partially resistant to 1,25D. Resistance to nuclear receptor (NR) agonists is a common event that occurs in other NR-related treatments. For example, some leukemias develop resistance to the usually effective retinoic acid (RA) treatment. However, treating RA-resistant cells with HDAC inhibitors (HDACi) sensitizes them to RA. Thus, this study aims to investigate how treatment with TSA, an HDACi, would affect the response of SCC4 cell lines to 1,25D. We found that TSA had a variety of effects on 1,25D-regulated gene expression. Combined treatment with 1,25D and TSA increased the expression of cell-cycle regulating proteins, but also enhanced the downregulation of key target genes. Given the potential of the 1,25D/HDACi combination in combating cancers, two chimeric compounds, each containing parts of 1,25D and an HDACi, were synthesized in collaboration with Dr. James Gleason (Dept. of Chemistry, McGill). These 1,25D analogs have the HDACi-like structure replacing the 1,25D side chain. Both compounds proved to be agonists of the vitamin D receptor. Moreover, the TSA-substituted compound, called triciferol, effectively induced a-tubulin as well as histones acetylation. This study underlines the potential of combining 1,25D and TSA in cancer treatment, and reveals that bi-functional 1,25D analogs can be produced with potentially enhanced therapeutic activity.

The rapid discovery of novel therapeutic agents, targeting the specific mechanism of cancer progression, invasion and angiogenesis, necessitates the development and validation of efficient techniques to assess the therapeutic efficacy of these drugs in vivo. Recently the development of dedicated PET scanners for the imaging of small animals, such as the microPET system (CTI Concorde R4), has allowed for the high-resolution functional and molecular imaging of murine and rodent models of disease. This study, investigates the ability of microPET imaging, using the 18F labelled 2-fluoro-2-deoxyglucose (FDG) PET tracer, to detect the therapeutic efficacy of novel targeted therapies in a rat model of glioma. This technique potentially allows for the rapid and high-throughput assessment of tumour response and evaluation of efficacy of such therapeutic agents in vivo at the pre-clinical stage and will, consequently, facilitate the translation of these novel drugs from the discovery to the clinical phases. / La découverte accélérée de nouvelles molécules thérapeutiques qui ciblent lesmécanismes de progression du cancer tels que l'invasion et l'angiogenèse, nécessite lamise au point et la validation de techniques efficaces qui permettent d'évaluer l'efficacitéthérapeutique de ces agents in vivo. Le développement récent des scanners detomographie à émission de positron (TEP) dédiés à l'imagerie de petits animaux(microPET, CT! Concorde R4), permet aujourd'hui d'obtenir une image fonctionnelle etmoléculaire de haute résolution des modèles rongeurs. Cette étude s'intéresse au potentieldu 18F-2-fluoro-2-deoxyglucose (FDG) en utilisant l'imagerie microPET dansl'évaluation de l'efficacité de nouveaux agents thérapeutiques dans un modèle de gliomechez le. rat. Cette technique pourrait éventuellement mener à une évaluation rapide et àgrande échelle de la réponse tumorale, ainsi que la mesure de l'efficacité d'agentsthérapeutiques in vivo au stade d'étude préclinique. Globalement, cette étude a pour butde faciliter la transition entre la découverte de nouvelles molécules thérapeutiques et leursapplications cliniques.

A current initiative to eliminate lymphatic filariasis (LF), headed by the World Health Organization, aims to interrupt transmission of the disease through yearly community-wide treatment with the broad spectrum anthelmintic albendazole (ABZ), in combination with ivermectin (IVM) or diethylcarbamazine (DEC). Over the years, the use of both ABZ and IVM in the treatment of veterinary parasites has led to widespread anthelmintic resistance against these drugs. In this study, we genotyped microfilaria of Wuchereria bancrofti, a causative agent of LF, in order to detect the presence of mutations which confer ABZ resistance in other parasites, and we identified such mutations in worms obtained from untreated patients in Ghana and Burkina Faso, West Africa. Microfilaria from patients who had been treated with ABZ + IVM, had a significantly higher frequency of the resistant genotype, and this frequency was even higher in worms from patients that had received two rounds of treatment. In addition, the untreated population of microfilaria had an excess of homozygotes in the population. This excess homozygosity was equivalent to a Wright's Inbreeding Statistic of FIT= 0.44, and we found that the population was significantly subdivided between patients. In order to better understand the mechanisms and factors involved in the potential spread of ABZ resistance, caused by such mutations, through a population of Culex-transmitted W. bancrofti, we developed a deterministic model that incorporates genotype structure into the epidemiological model EPIFIL. This model predicts that the combination of ABZ + DEC leads to stronger selection for the resistant genotype than ABZ + IVM, and that drug efficacy assumptions are an important factor affecting the spread of drug resistance. Treatment coverage, non-random mating, initial allele frequency and number of treatments also had substantial impact on the speed and magnitude of the spread of ABZ resistance. When we expanded this model to include potential IVM-resistance alleles we found that, under ABZ + IVM treatment, selection for resistance to either drug is enhanced by the presence of resistance against the second drug. Similarly, excess homozygosity caused by parasite non-random mating may increase selection for a dominant IVM resistance allele through enhancing the spread of a recessive ABZ resistance allele. Resistence developed more slowly when it was inherited as a polygenic trait. Results from this study suggest that resistance monitoring is crucial, as resistance may not be apparent until treatment is stopped, recrudescence occurs and treatment is reapplied.

The catechol-O-methyltransferase (COMT) gene is the predominant means of dopamine deactivation within the prefrontal cortex (PFC), a brain locus implicated in Attention deficit/hyperactivity disorder (ADHD). Dopamine dysregulation is a significant contributor to the pathophysiology of ADHD and Methylphenidate (MPH), an effective treatment for ADHD, and acts at least in part, through modulation of dopamine levels in the PFC. Thus, we tested the hypothesis that the Catechol-O-Methyltransferase (COMT) Val108/158 Met polymorphism modulates behavioral dimensions relevant for ADHD and/or response of these behavioral dimensions to MPH and/or neuropsychological functions considered relevant for ADHD. No genotype or genotype by treatment interaction effects were observed for behavioral response to MPH. No genotype effects were observed using the family-based approach. Marginal genotype effects were observed between the Met/Met genotype and some but not all aspects of executive functioning. Overall, these results do not support the implication of the COMT Val108/158 Met polymorphism in ADHD, ADHD relevant behaviours or response to methylphenidate, but weakly implicate COMT gene in some aspects of executive functions in children with ADHD. Given that gene effects on behaviours are likely to be very small, a much large sample would be needed in order to establish these results, both negative and positive, with better confidence.

Aims. The overall aim was to examine the severity, treatment and level of control in patients with asthma in primary care in Sweden. The specific aims were to assess what matters to asthma patients, evaluate symptoms, medication and identify factors related to asthma severity, compare the extent of asthma control in 2001 and 2005, and investigate the development of asthma and degree of asthma control in adolescents and young adults who had reported asthma six years earlier. Methods. The first study was a telephone interview of a representative sample of Swedish asthmatics. In the second study a random sample of 1,136 patients answered two questionnaires. A classification of the asthma severity similar to that in the GINA guidelines was made. In the third study two surveys were performed, in 2001 and in 2005, with a random sample of 1,012 and 224 asthma patients, respectively, and a classification of asthma control similar to the recent GINA guidelines was made. In the fourth study 71 individuals who reported physician-diagnosed asthma in a population-based survey in 1997 and were defined as current asthmatics, were reinvestigated in 2003 with a skin prick test, methacholine challenge test, eucapnic voluntary hyperventilation test and measurement of exhaled nitric oxide. Results. Common situations causing symptoms of asthma were physical exertion and contact with pets. Nocturnal symptoms were frequent. In primary care 35% of the women and 24% of the men were classified as having severe asthma. Female sex, increasing age, not filling the asthma prescription owing to cost, daily smoking, and pollen allergy increased the odds of having severe asthma. In 2001, 37% had achieved asthma control, as compared with 40% in 2005. Uncontrolled asthma was more common in women and smokers. In the 2003 study of adolescents and young adults with asthma six years earlier, the definition of current asthma was fulfilled by 50 of the 71 subjects and one third had achieved asthma control. Conclusions. The majority of the asthmatics reported a large number of symptoms and limitations in their daily living. Many asthma patients in primary care have insufficient asthma control. One reason for lack of control might be undertreatment with inhaled corticosteroids.