Patients admitted to intensive care unit (ICU) are known to develop significant impairments in physical function. Patients with critical illness suffer up to 30% reductions in muscle size within the first ten days of admission to the ICU. Muscle strength testing, Medical Research Council-sum score, is current gold-standard to diagnosis ICU-acquired weakness and predicts risk of mortality and long-term physical function. Muscle power different from muscle strength in that it accounts for velocity of movement, is potentially a better independent predictor of function that has not been studied in this population. In addition, we hypothesize that muscle size and quality measured through ultrasound imaging has better applicability and prediction that strength testing. Therefore, we prospectively collected data surrounding these muscle parameters in patients admitted to the medicine ICU at University of Kentucky. Primary outcomes included physical function, muscle power with a novel assessment tool for the critically ill population, muscle strength, and muscle size and quality assess through ultrasound imaging. 36 patients admitted to ICU and 18 aged-matched controlled were enrolled. Patients had significantly lower scores on muscle power assessment at ICU discharge (33.6 ±19.0 W; t= 4.01, p < 0.001) and at hospital discharge (40.9 ±16.5 W; t= 4.81, p < 0.001) in comparison to controls (59.3± 14.7 W). Patients with better scores on muscle power assessment had significantly better scores on physical function measures (Six-minute walk test; rs = 0.548, p = 0.0001). Muscle size (cross-sectional area of rectus femoris muscle) and muscle power were strongly correlated (rs = 0.66, p < 0.0001). These data suggest that patients with critical illness have significantly reduced muscle power which directly related to deficits in physical function.

Objectives: to determine the effectiveness of bariatric surgery to reduce the risk of cardiovascular events such as coronary heart disease, stroke, cardiovascular mortality, and total mortality in morbidly obese patients, compared with a non-surgical treatment and no intervention control group. Methods: a systematic review was carried out with cohort-type studies that evaluated, with a minimum follow-up of one year, morbidly obese adults who had undergone bariatric surgery compared to a control group of non-surgical treatment and without intervention in relation to the cardiovascular events such as coronary heart disease, stroke, cardiovascular mortality, and total mortality in morbidly obese patients. Results: 14 studies were selected that met our inclusion criteria. 44,912 patients who underwent bariatric surgery and 208,347 non-surgical controls were included. The high heterogeneity of the included studies did not allow the meta-analysis to be carried out. However, most of the individual results show decreased risk of the outcomes studied. A subgroup analysis was performed, where Bariatric Roux-en-Y surgery reduces the risk of coronary artery disease by approximately 60%. In morbidly obese diabetic patients, our calculations showed a risk reduction of 80% for cardiovascular mortality and 70% for total mortality. Finally, our calculations show a 58% decrease in cardiovascular mortality in studies with a follow-up of 2 or more years. Conclusions: Our study suggests that bariatric surgery is beneficial for morbidly obese adult patients at risk of presenting cardiovascular events. / Objetivos: determinar la efectividad de la cirugía bariátrica para disminuir el riesgo de eventos cardiovasculares como enfermedad coronaria, accidente cerebrovascular, mortalidad cardiovascular y mortalidad total en pacientes obesos mórbidos, comparado con un grupo control de tratamiento no quirúrgico y sin intervención. Métodos: se realizó una revisión sistemática con estudios de tipo cohortes que evalúen, con seguimiento mínimo de un año, a adultos obesos mórbidos que se hayan sometido a cirugía bariátrica en comparación a un grupo control de tratamiento no quirúrgico y sin intervención en relación con los eventos cardiovasculares como enfermedad coronaria, accidente cerebrovascular, mortalidad cardiovascular y mortalidad total en pacientes obesos mórbidos. Resultados: se seleccionaron 14 estudios que cumplieron nuestros criterios de inclusión. Se incluyeron 44 912 pacientes que se sometieron a cirugía bariátrica y 208 347 controles no quirúrgicos. La alta heterogeneidad de los estudios incluidos no permitió realizar el metaanálisis. Sin embargo, la mayoría de los resultados individuales muestran disminución del riesgo de los desenlaces estudiados. Se realizó un análisis por subgrupos, en donde la cirugía bariátrica en Y de Roux disminuye el riesgo de enfermedad coronaria en aproximadamente 60%. En pacientes obesos mórbidos diabéticos nuestros cálculos mostraron reducción del riesgo en 80% de mortalidad cardiovascular y 70% de mortalidad total. Por último, nuestros cálculos demuestran disminución del 58% de la mortalidad cardiovascular en los estudios con un seguimiento de 2 a más años. Conclusiones: Nuestro estudio sugiere que la cirugía bariátrica es beneficiosa para los pacientes adultos obesos mórbidos en riesgo de presentar eventos cardiovasculares / Tesis

Représentant 43% des décès rapportés au cours des dix dernières années, la mort subite due à un événement cardiaque est la cause de décès au travail la plus fréquente chez les pompiers américains. Des études démontrent que le risque d’événements cardiaques au travail chez les pompiers est accentué par deux causes principales, la première étant la présence d’une maladie coronarienne, d’une cardiomégalie/hypertrophie ventriculaire gauche (HVG) ou de dommages occasionnés antérieurement par un infarctus du myocarde, la seconde étant l’importante contrainte cardiovasculaire subie au travail. Aucune étude n’a été réalisée pour évaluer l’état de santé cardiovasculaire des pompiers et pompières du Québec. Une telle étude permettrait d’en connaître davantage sur leur risque de maladies et d’événements cardiovasculaires. Par ailleurs, on constate que la prévalence des facteurs de risque des maladies cardiovasculaires (MCV) est élevée chez les pompiers américains, ce qui corrèle avec le nombre élevé d’événements cardiaques au travail. Le premier objectif de cette thèse était donc de dresser un portrait de la santé cardiovasculaire des pompiers et pompières du Québec. Ensuite, dans le but de réduire le risque d’événements cardiaques au travail, il était pertinent d’étudier une stratégie de prévention des MCV chez les pompiers. Le risque de développer une maladie coronarienne ou une cardiomégalie/HVG pourrait être réduit en adoptant et maintenant de saines habitudes de vie, dont une pratique régulière d’activités physiques. Plusieurs services de sécurité incendie au Québec permettent aux pompiers de faire du conditionnement physique en caserne pendant les heures de travail. Cette pratique pourrait contribuer à augmenter leur quantité d’activités physiques hebdomadaire et à améliorer leur santé cardiovasculaire. Le deuxième objectif de cette thèse était donc de comparer la pratique d’activités physiques hebdomadaire et différents indicateurs de santé cardiovasculaire chez les pompiers qui font et ceux qui ne font pas de conditionnement physique pendant les heures de travail. Enfin, dans le but de réduire le risque d’événements cardiaques au travail, il semblait pertinent de s’intéresser à la prévention de la contrainte cardiovasculaire subie au travail chez les pompiers, considérant qu’elle agit comme « déclencheur ». Cette contrainte pourrait être réduite en évitant d’écourter les périodes de repos octroyées entre les phases de travail lors d’une intervention. Le troisième objectif de cette thèse était de comparer et de caractériser la contrainte cardiaque engendrée par deux interventions simulant les tâches du métier de pompiers, soit deux phases de travail identiques entrecoupées d’une période de récupération passive courte versus prolongée. Les résultats principaux de cette thèse montrent qu’une proportion importante de pompiers (Chapitre 2) et pompières (Chapitre 3) du Québec sont à risque moyen/élevé de MCV. Ils montrent aussi que les pompiers qui font du conditionnement physique pendant les heures de travail pratiquent plus d’activité physique par semaine et présentent de meilleurs indicateurs de santé cardiovasculaire que les pompiers qui n’en font pas (Chapitre 4). Finalement, les résultats montrent qu’une période de récupération passive d’une durée de 5 minutes entre deux phases de travail de 25 minutes lors d’une simulation d’intervention engendre une contrainte cardiaque largement plus importante qu’une période de 20 minutes et que cette différence semble être principalement redevable à une contrainte thermique et une déshydratation plus importantes (Chapitre 5). Ces projets de recherche ont été subventionnés par les Fonds de recherche du Québec – Santé sous la forme d'une bourse d'étude de formation de doctorat. / Accounting for 43% of deaths reported in the past decade, sudden cardiac death is the most common cause of on-duty deaths among US firefighters. Studies show that the risk of on-duty cardiac events in firefighters is accentuated by two main causes: the first is the presence of coronary heart disease, cardiomegaly/left ventricular hypertrophy (LVH) and/or damage caused previously by a myocardial infarction, the second being the important cardiovascular strain suffered at work. No studies have been conducted to assess the cardiovascular health status of Québec firefighters. Such a study would allow us to know more about their risk of cardiovascular diseases (CVD) and on-duty cardiac events. Futhermore, the prevalence of CVD risk factors was shown to be high among US firefighters, consistent with the high number of on-duty cardiac events. The first objective of this thesis was thus to assess the cardiovascular health profile of Québec male and female firefighters. Second, in order to reduce the risk of on-duty cardiac events, it was relevant to pore over the prevention of CVD in firefighters. The risk of developing coronary heart disease and/or cardiomegaly/LVH could be reduced by engaging in and maintaining healthy lifestyle behavior including regular physical activity. Several fire departments in Québec allow firefighters to do on-duty physical training in fire stations. This could help increase their weekly physical activity level and improve their cardiovascular health. The second objective of this thesis was to compare the weekly physical activity level and various cardiovascular health indicators in firefighters who physically train on duty in the fire station and those who do not. Lastly, in order to reduce the risk of on-duty cardiac events, it was also relevant to look at the prevention of cardiovascular strain suffered by firefighters, considering that it acts as a "trigger". This could be reduced by avoiding shortened recovery periods between periods of work during interventions. The third objective of this thesis was to compare and characterize the cardiac strain generated by two firefighting simulations consisting of two identical work bouts intercalated with a short vs. extended passive recovery period. iv The main results of this thesis show that a high proportion of Québec male and female firefighters are at moderate to high risk of CVD. They also show that firefighters who physically train on duty in fire stations have a higher weekly physical activity level and have better cardiovascular health indicators compared to firefighters who do not. Finally, the results show that a passive recovery period of 5 minutes between two 25-minute work bouts during a firefighting simulation results in a greater cardiac strain than a 20-minute recovery period and that this difference seems to be mainly due to a greater thermal strain and dehydration. These projects were funded by Fonds de recherche du Québec – Santé in the form of a doctoral research scholarship.

Orientador: Robison José Quitério / Resumo: Introdução: Em decorrência do número elevado de comorbidades associadas à Doença Arterial Coronariana (DAC), os modelos de previsão de risco para cirurgia cardíaca foram desenvolvidos com a finalidade de melhor caracterizar os fatores que influenciam os resultados deste procedimento. Além dos escores de risco utilizados mundialmente “European System for Cardiac Operative Risk Evaluation” (EUROSCORE II) e “Society of Thoracic Surgeons” (STS), a Variabilidade da Frequência Cardíaca (VFC) tem surgido como um novo instrumento de previsão do risco cardiovascular e cirúrgico. Objetivo: Caracterizar os pacientes eletivos para cirurgia de revascularização do miocárdio na região de Marília-SP-Brasil, quanto aos fatores de risco e controle neural do coração; Verificar se existe correlação entre os índices da VFC e os escores de risco cirúrgico EUROSCORE II e STS. Amostra: Foi composta por indivíduos de ambos os sexos, acima de 50 anos, eletivos para cirurgia de revascularização do miocárdio (Hospital Santa Casa de Misericórdia de Marília). O Grupo Controle (GC) foi composto por indivíduos de ambos os sexos, acima de 50 anos, saudáveis. Procedimentos do Estudo: Foi realizada a anamnese na qual foram avaliados os fatores de risco para doença cardiovascular. O registro do intervalos RR foi obtido na postura decúbito dorsal, por 20 minutos, em respiração espontânea. Os índices da VFC (lineares e não lineares) foram analisados, comparados com um grupo controle e correlacionados com valores ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Introduction: Due to the high number of comorbidities associated with Coronary Artery Disease (CAD), risk prediction models for cardiac surgery were developed with the purpose of better characterizing the factors that influence the results of this procedure. In addition to the European System for Cardiac Operative Risk Evaluation (EUROSCORE II) and Society of Thoracic Surgeons (STS) worldwide, Heart Rate Variability (HRV) has emerged as a new tool for predicting cardiovascular risk and surgical. Objective: To characterize elective patients for myocardial revascularization surgery in the Marília-SP-Brazil region, regarding risk factors and neural control of the heart; To verify if there is a correlation between the HRV indices and the surgical risk scores EUROSCORE II and STS. Sample: It was composed of individuals of both sexes, over 50 years old, elective for myocardial revascularization surgery (Santa Casa de Misericórdia Hospital of Marília). The Control Group (CG) was composed of individuals of both genders, over 50 years, healthy. Study Procedures: An anamnesis was performed in which the risk factors for cardiovascular disease were evaluated. RR interval recording was obtained in the dorsal decubitus position for 20 minutes in spontaneous breathing. The HRV indices (linear and non-linear) were analyzed, compared to a control group and correlated with values obtained from EUROSCORE II and STS. The data were organized as descriptive statistics, with values of mean and stan... (Complete abstract click electronic access below) / Mestre

Institute for Gender and Youth Studies / PHDGS / Historically, the cardiovascular disease (CVD) has internationally been viewed as a man’s disease. This is witnessed by the high number of males who have fallen victim to this scourge. However, with rapid changes in today’s societies, the disease has increasingly become a public health concern among women also. This study aimed to explore rural women’s perspectives of CVD in Gwanda South Rural District. The study was guided by a feminist perspective where theories of gender such as social construction feminism, intersectionality and standpoint theory, were employed as a theoretical framework. In this process, the research endeavoured to unearth some contradictions inherent in the manner in which women view CVD. The population of the study comprised of females aged 21-60 years residing in Gwanda South Rural District of Zimbabwe. An exploratory case study design was adopted and this guided the qualitative data collection and analysis. Purposeful sampling technique was used to select 16 participants for semi-structured interviews and six participants for focus group discussions. Data were analysed using thematic analysis which is an essential tool for qualitative data analysis. Data were presented and discussed as themes and subthemes. The concepts of credibility, transferability, dependability and confirmability were used to describe and ensure various aspects of trustworthiness. Ethical considerations like informed consent, confidentiality and anonymity and no harm to participants were ensured. The following seven themes were derived from the study; women’s knowledge of CVD, causes of CVD, prevention of CVD, perceived effects of CVD, difference in experiences of CVD, assistance of women with CVD and management of CVD. Findings revealed that women had limited knowledge of most CVDs but were familiar with hypertension and stroke. Various symptoms of CVD were identified. It was concluded that rural women do not have adequate knowledge of CVDs. A lot should be done by the government and other stakeholders to ameliorate cardiovascular health in rural women. / NRF

Lorsqu’elle est comparée à la pression artérielle (PA) brachiale, la PA centrale est un meilleur reflet du stress hémodynamique infligé aux organes cibles. Les objectifs de ce mémoire sont de clarifier le rôle de la PA centrale pour la prédiction du risque cardiovasculaire (CV), de définir un seuil permettant le diagnostic d’une hypertension centrale et de définir l’effet sur la PA centrale de certains paramètres, tels que les statines et le cholestérol LDL. La base de données CARTaGENE comportant 20 004 sujets a été utilisée. La PA centrale était connue (mesurée à l’aide de l’appareil SphygmoCor Px qui utilise une calibration de type I), ainsi que les autres facteurs de risques CV. Des données prospectives permettant de connaître l’incidence d’événements CV majeurs étaient disponibles. Dans un premier temps, des modèles de régression de Cox et des mesures de discrimination et de reclassification ont permis de comparer la PA systolique centrale et brachiale pour la prédiction du risque CV. Un seuil permettant le diagnostic d’une hypertension centrale a aussi été déterminé à l’aide de l’index de Youden. L’association entre la PA centrale, le cholestérol LDL et les statines a été déterminée à l’aide de régressions linéaires et d’ANOVA. Une analyse de médiation a permis d’éclairer l’effet des statines sur la PA centrale, à savoir si celui-ci est médié par une baisse concomitante du cholestérol LDL. Ces analyses ont permis de déterminer que la PA centrale ne procure qu’une amélioration marginale dans la prédiction du risque cardiovasculaire lorsque comparé à celle de la PA brachiale. Une PA systolique centrale de 120 mmHg a été identifiée comme le meilleur seuil pour poser le diagnostic d’une hypertension centrale lorsqu’évaluée avec un appareil avec calibration de type I. De plus, la PA centrale est influencée par la prise de statines et son effet n’est que partiellement médié par une baisse concomitante du cholestérol LDL. / Compared to brachial blood pressure (BP), central BP is thought to be a better reflection of the hemodynamic strain on target organs. It is unclear though whether this translates into improved cardiovascular (CV) risk stratification when central BP is compared to brachial BP. The objectives of this thesis are to clarify the role of central BP in CV risk stratification, to define a threshold for the diagnosis of central hypertension and to determine what are the impacts of parameters, such as statins and LDL cholesterol, on central BP. The CARTaGENE database, which is comprised of 20,004 individuals, was used for these studies. The central BP (measured with the SphygmoCor Px device and type I calibration) as well as other CV risk factors were known. Prospective data for the incidence of major adverse cardiovascular events (MACE) was available. Cox proportional hazard models and measures of discrimination and reclassification were used to compare central systolic BP and brachial systolic BP in their ability to predict CV risk. A central hypertension threshold was determined using Youden’s index. The association between central BP, LDL cholesterol and statins were assessed using linear regression models and ANOVA. The interactions between central BP, statins and cholesterol LDL were assessed with a mediation analysis. Central BP was only marginally superior to brachial BP in CV risk prediction. A central hypertension threshold of 120 mmHg was identified. Statins reduced both brachial and central BP in a similar fashion, and cholesterol LDL was only partially responsible for the effect of statins on BP. To conclude, central BP, when assessed using type I calibration, is not superior to brachial BP in CV risk prediction. These studies also clarified the central hypertension threshold and the impact of statins and cholesterol LDL on central BP.

Les maladies cardiovasculaires (MCV) ont une prévalence élevée dans le monde et sont considérées comme la deuxième cause de mortalité chez la population canadienne. Les statines sont reconnues comme le traitement par excellence dans la prévention des MCV. Toutefois, les statines ne conviennent pas à tous les patients, potentiellement, en raison de la survenue d’effets secondaires et du manque d’efficacité. Avec l’avancement de la science, de nouvelles thérapies voient le jour dans le milieu cardiovasculaire. Les inhibiteurs de la proprotéine convertase subtilisine-kexine de type 9 PCSK9 (iPCSK9) constituent un traitement efficace pour réduire les évènements cardiovasculaires. Cependant, ces thérapies sont dispendieuses pour le système de santé. Cette thèse a pour but d’explorer la pharmacoéconomie des thérapies dispendieuses ayant démontrées une efficacité clinique importante dans le traitement préventif des MCV. La pharmacoéconomie est un outil d’évaluation destiné aux décideurs ayant comme objectif d’optimiser l’utilisation des ressources humaines et financières. Tout d’abord, dans un premier article, nous avons évalué l’efficacité maximale d’une thérapie hypolipémiante à partir des grilles de risque cardiovasculaires. Selon les résultats obtenus, l’efficacité maximale qu’il est raisonnable d’espérer a correspondu à une diminution du risque relatif variant entre 0,46 et 0,66. Ensuite, dans un deuxième article, nous avons estimé l’efficacité d’une thérapie dispendieuse dans un contexte différent puisque les études cliniques étaient en cours. Avec l’aide d’un modèle de Markov, la propension à payer a été fixée à deux seuils distincts, alors que le coût d’acquisition de la thérapie est demeuré fixe. Nos résultats ont estimé que pour atteindre les seuils de propension à payer de 50 000 $ et 100 000 $ par année de vie ajustée pour la qualité, l’efficacité devrait être de 0,58 et 0,78 respectivement. Finalement, l’étude randomisée contrôlée établissant l’efficacité clinique des iPCSK9 a été publiée. Nous avons donc pu évaluer le coût-utilité réel des iPCSK9 avec une nouvelle méthode de simulation, nommée Conditions et évènements discrètement intégrés. Cette étude est l’objet 2 de mon troisième article. Les résultats de cet article ont estimé que l’iPCSK9 n’est pas coût-efficace selon l’efficacité obtenue dans les études cliniques. En conclusion, suite aux résultats présentés dans cette thèse rédigée par articles, il serait envisageable d’intégrer dans le modèle pharmacoéconomique l’option d’un test génétique afin d’individualiser le traitement de chaque patient. / Cardiovascular diseases (CVD) have a high prevalence worldwide and are considered the second leading cause of death in the Canadian population. Statins are recognized to be the gold standard treatment in the prevention of CVD. However, statins are not suitable for all patients, potentially because of side effects and lack of efficacy. With the advancement of science, new therapies are emerging in the cardiovascular field. Inhibitors of proprotein convertase subtilisin-kexin type 9 (iPCSK9) have been shown to be effective in reducing cardiovascular events. However, these therapies are expensive. This article-based thesis aims to explore the pharmacoeconomics of expensive therapies that have demonstrated significant clinical efficacy in the preventive treatment of CVD. Pharmacoeconomics is an evaluation tool for decision-makers with the objective of optimizing the use of human and financial resources. In the first publication, we evaluated the maximum effectiveness of lipid-lowering therapy from cardiovascular risk grids. According to our results, this maximum expected benefit fluctuates between 0.46 and 0.66. In the second publication, we estimated the effectiveness of an expensive therapy. At the time of our second publication, the results of the randomized controlled trial evaluating the clinical efficacy of iPCSK9 had not been published yet. Therefore, we used a Markov model to estimate the necessary clinical efficacy of PCSK9 inhibitors to reach two arbitrarily selected willingness-to-pay (WTP) thresholds. Our results showed that an efficacy of 0.58 and 0.78 were necessary to reach WTP thresholds of $50,000 and $100,000 per quality-adjusted life years respectively. Once the clinical efficacy of iPCSK9 was published, we evaluated their cost-utility. This was the object of our third article and a new simulation method named Discretely Integrated Condition was used. Our results suggested that at the current price, the PCSK9 inhibitors were not cost-effective. Following the results presented in this article-based thesis, it would be of interest to integrate the option of a hypothetical genetic test into the pharmacoeconomic model. This genetic test would be able to identify good responders in order to optimize the treatment of each individual patient.

Objective: Cardiovascular diseases are the leading cause of death. The gold standard for their diagnosis and treatment are angiographic procedures. Clinicians rely on dedicated and specialized equipment for these interventions, e.g. angiography systems. The speed of the associated development is important as better technology enables progress in treatment methods and clinical outcomes. The goal of this article is to show how to optimize the innovation and development process such that it takes minimal time. Methods: 672 data sets on 302 topics were collected over 47 months during a long-term observation of the innovation and development process of angiographic systems. The total data collected is equivalent to efforts worth 30 man-years. This input was used to calculate key process parameters, analyse key process roles, evaluate the use of problem-solving methods and identify key technologies. We also developed a process model comprising the primary innovation sources, important input providers and key processes. This model is characterized by a continuous loop for the innovation and development process. Results: The conducted literature research identifies this closed loop process model as being unique in comparison to the well-established models proposed by Brockhoff, Cooper, Crawford, Durfee, Ebert, Eppinger, Hughes, Pleschak, Thom, Ulrich, Vahs and Witt. According to the best knowledge of the authors no comparable data collection has been performed and presented anywhere else yet. When analysing our 672 data sets, we found that the median process time ( in this data pool (n=672) was to be 10 weeks (p<0,05). The median number of task owners (xPA) per task across all topics was 2. Our data revealed that the number of task owners had a direct impact on the process time. For data sets with up to eight task owners the relationship between process time and task owners can be described as tPd=3.6*xPA^1.4. The median time of owning a topic was determined for Sales (7 weeks), Service (11 weeks), Customer Relationship Management (6 weeks), Product Lifecycle Management (10 weeks) and Research & Development (11 weeks). Main input providers were Sales (53%) and customers (28%). Sales (42%) and PLM (37%) are significant connectors. Problem solvers are PLM (35%), CRM (27%) and R&D (27%). The problem-solving methods were analysed and it was found that clarification (77%) as well as dialog and variation method (both 50%) were used most often. We found that changes to the application software (33%), mechanics, device interfaces and user interface (all 21%) are the four out of six components that were involved in most often. In the analysed datasets a potential of an up to 20% shorter process time was identified. Conclusion: This article proposes a new model for the innovation and development process. Based on our data, we recommend to apply a continuous loop process in the context of innovation and development of medical devices. Our results can, for example, be used for Activity Based Costing Approach or be applied to bring new or upgraded angiography systems faster to market benefitting patient outcome due to improved diagnosis and treatment of cardiovascular diseases.

Breast cancer, osteoporosis, and coronary heart disease (CHD) are three major threats to women’s health. Postmenopausal women with breast cancer are also at high risk for osteoporosis and CHD. Adjuvant tamoxifen therapy is not only an effective treatment for breast cancer, but has been shown to have a beneficial effect on bone and the cardiovascular system. Although tamoxifen has been convincingly demonstrated to be able to preserve bone mineral density (BMD), an unexpected increase of risk of fractures in patients treated with tamoxifen has been reported. The findings of the association of tamoxifen and CHD from previous studies were either borderline or inconsistent. To clarify the discrepancy between BMD and fractures and test the potential beneficial effect of tamoxifen on CHD, I conducted a series of retrospective studies in postmenopausal women with breast cancer who participated in the Cancer Surveillance in HMO Administrative Data (IMPACT study) or the Study of Osteoporotic Fractures (SOF). In patients who participated in the IMPACT study, I demonstrated that the association of tamoxifen and fracture incidence varied at different skeletal sites. Although the association of tamoxifen and fractures in the spine (HR=0.40, 95% CI: 0.09-1.85), wrist (HR=2.49, 95% CI: 0.88-7.06), and total body (HR=0.87, 95% CI: 0.49-1.55) was inconclusive, tamoxifen was associated with an apparent reduction of the risk of hip fracture (HR=0.41, 95% CI: 0.17-1.03, p=0.0565). Importantly, the pattern of observed association of tamoxifen with the risks of fractures among postmenopausal women with breast cancer is consistent with its widely reported preserving effect on bone mineral density. Using SOF data, I found that the association between BMD and fractures in women with breast cancer varied at different skeletal sites, and type of BMD measured. Non-specific BMD was not associated with hip fracture (HR=1.12; 95% CI: 0.78, 1.59). Site-specific BMD was more likely linked with hip fracture (HR=1.43, 95% CI: 0.99, 2.08) while change in BMD did not predict hip fracture (HR=1.05; 95% CI: 0.63, 1.72). The association of spine morphometric fracture with either non-specific or spine-specific BMD was similar (OR=1.40; 95% CI: 1.04, 1.90; OR=1.35, 95% CI: 0.99, 1.85, respectively). Overall, the association of BMD and fracture in elderly women with breast cancer is weak. Only site-specific BMD appears to have a consistently modest association with fractures in the corresponding skeletal sites. In the IMPACT study population, compared to patients without tamoxifen, the overall incidence of CHD in tamoxifen-treated patients was lower (adjusted HR=0.60, 95% CI: 0.40-0.88). For each year of tamoxifen use, there was a statistically significant decrease in the risk of CHD (HR=0.90, 95% CI: 0.82-0.98). Further analyses categorized by length of tamoxifen use showed that an apparent association with a decreased CHD risk was found in patients who received tamoxifen for two to five years (HR=0.54, 95% CI: 0.33-0.86). No association was detected after the discontinuation of tamoxifen therapy. In summary, I detected a possible benefit associated with tamoxifen on fractures in the hip, the most common fracture site. I also found that BMD did not predict osteoporotic fractures well in postmenopausal women with breast cancer. In addition, I demonstrated that tamoxifen was associated with a reduced risk of CHD in postmenopausal women with breast cancer in a dose-dependent manner. An apparent benefit was found in those patients who received tamoxifen therapy for at least two years.

KCNE1 (E1) peptide is the founding member of the KCNE family (1-5), which is a class of type I transmembrane ß-subunits. KCNE1 peptides assemble with and modulate the gating, ion conducting properties and pharmacology of a variety of voltage-gated K+ channel a-subunits, including KCNQ1 (Q1). Mutations that interfere with the function of either E1 and/or Q1 and disrupt the assembly and trafficking of KCNE1- KCNQ1 channel complexes give rise to diseases such as Romano-Ward (RW) and Jervell Lange Nielsen Syndrome (JLNS), two different forms of Long QT Syndrome (LQTS). Using enzymatic deglycosylation assays, immunofluorescence techniques and quantitative cell surface labeling, we showed that KCNE1 peptides are retained in the early stages of the secretory pathway as immaturely N-linked glycosylated proteins. KCNE1 co-assembly with KCNQ1 leads to E1 progression through the secretory pathway and glycan maturation, resulting in cell surface expression. N-linked glycosylation of some membrane proteins is critical for proper folding, co-assembly and subsequent trafficking through the biosynthetic pathway. Previous studies have shown that genetic mutations that disrupt one of the two N-linked glycosylation sites on KCNE family members lead to LQTS (T7I, KCNE1 and T8A, KCNE2) (Schulze-Bahr et al., 1997; Sesti et al., 2000a; Park et al., 2003). Having confirmed that KCNE1 proteins acquire N-linked glycans, we examined the kinetics and efficiency of N-linked glycan addition to KCNE1. We showed that KCNE1 has two distinct N-linked glycosylation sites. The N-terminal sequon is a traditional co-translational site. The internal sequon (which is only ~ 20 residues away from the N-terminal sequon) acquires N-linked glycans primarily after protein synthesis (post-translationally). Surprisingly, mutations that prevent N-glycosylation at the cotranslational site also reduce the glycosylation efficiency of post-translational glycosylation at the internal sequon, resulting in a large population of unglycosylated KCNE1 peptides that are retained in the early stages of the secretory pathway and do not reach the cell surface with their cognate K+ channel. We showed that KCNE1 post-translational N-glycosylation in the endoplasmic reticulum is a cellular mechanism that ensures E1 proteins acquire the maximal number of glycans needed for proper channel assembly and trafficking. Our findings provide a new biogenic mechanism for human disease by showing that the JLNS mutation, T7I, not only inhibits glycosylation of the N-terminal sequon, but also indirectly prevents the glycosylation of the internal sequon, giving rise to a large population of assembly incompetent hypoglycosylated KCNE1 peptides. To further investigate the two N-linked glycosylation sites on KCNE1, we generated structure-function deletion scans of KCNE1 and performed positional glycosylation scanning mutagenesis. We examined the glycosylation pattern of glycosylation mutants in an effort to define the glycosylation window important for proper KCNE1 assembly and trafficking. Our findings suggested a nine amino acid periodicity to serve as a desirable glycosylation site and a better substrate for N-glycosylation. Appendix II shows work on the characterization of the C-terminally HA-tagged KCNE1 protein, which was used throughout the experiments presented in Chapter II, Chapter III and Chapter IV. Analysis of the C-terminally HA-tagged KCNE1 protein revealed that in heterologous expression systems KCNE1 had an internal translational start site, a methionine at position 27. A proteolytic cleavage site was also identified at the arginine cluster spanning residues 32 through 38 bearing the two known Long QT mutations (R32H and R36H) (Splawski et al., 2000; Napolitano et al., 2005). My work in Professor Craig C. Mello’s lab during the first four years of my graduate study is presented in Appendix I. The highly conserved Wnt/Wingless glycoproteins regulate many aspects of animal development. Wnt signaling specifies endoderm fate by controlling the fate of EMS blastomere daughters in 4-cell stage Caenorhabditis elegans embryos. A suppressor genetic screen was performed using two temperature sensitive alleles of mom-2/Wnt to identify additional regulators of the Wnt/Wingless signaling pathway during C. elegans endoderm specification. Five intragenic suppressors and three extragenic suppressors of mom-2/Wnt embryonic lethality were identified. We cloned ifg-1, eIF4G homologue, as one of the extragenic suppressors suggesting an intriguing connection between the Wnt signaling pathway and the translational machinery.