Antigen presentation to T cells results in their activation through T Cell Receptor (TCR) stimulation, resulting in sustained elevation of cytosolic Ca2+ concentration critical for T cell activation. Sustained Ca2+ signals are important for the activation of Nuclear Factor of Activated T cells (NFAT), which is a key regulator of T cell activation through its transcriptional control of genes in multiple process including cytokine production, proliferation and differentiation(Rao, Luo, & Hogan, 1997). Recently it was shown that Stromal Interaction Molecule 1 (STIM1) inhibits plasma membrane Ca2+/ATPase 4 (PMCA4) function during T cell activation resulting in sustained elevation of Ca2+ signals(Ritchie, Samakai, & Soboloff, 2012). This interaction requires upregulation of both STIM1 and PMCA4. In this thesis, I hypothesize that changes in Ca2+ signals arising from transcriptional changes of STIM1 and PMCA are important for the efficient activation of T cells. In the first part of this thesis, I assess the transcriptional regulation of STIM1 and PMCA4. My in vitro studies show that expression of both proteins is regulated by the EGR family members, EGR1 and EGR4. Additionally, transcriptional regulation of PMCA inhibition by EGR1 and EGR4 is required for efficient activation of T cells. Interestingly, whereas significant roles for EGR1, EGR2 and EGR3 in T cell development and function have been established, a role for EGR4 has not, hitherto been elucidated. In the second half of this thesis, using qPCR, I reveal that EGR4 expression is stimulated by TCR engagement in primary double positive, CD4 and CD8 positive murine T cells. Further, EGR4-null mice exhibit shifts in early thymic development, although this does not affect the relative number of double or single positive T cells in the thymus. Interestingly, EGR4-null primary T cells exhibit normal Ca2+ entry, but fail to exhibit activation-induced inhibition of Ca2+ clearance. Although not all subsets of EGR1 and EGR4 null primary T cells exhibited decreased STIM1 expression, significant defects in proliferation, migration and/or cytokine production were observed upon stimulation in all populations, albeit to different extents. These findings reveal a two-faceted role in which EGRs regulate T cell development and function through both Ca2+-dependent and independent methods. I believe that these findings have important implications towards the general understanding of transcriptional control of Ca2+ signaling, as well as having a possible impact in the quest to advance therapies targeting immunological disorders. / Biochemistry

Denna fallstudie undersöker hur två marina system för rening av kväveoxider från rökgaser, EGR samt SCR, presterar med avseende på emissioner och ekonomi. En vanligt förekommande tvåtakt dieselmotor valdes att teoretiskt utrustas med respektive system där ett beräkningsprogram, CEAS, kunde användas för att genomföra beräkningar efter valda driftsförhållanden och därmed få ut relevant data. Med förbrukning av de för systemen erforderliga kemikalierna samt förbrukning av bränsle kunde kostnader beräknas efter inhämtande av priser. Med IMO:s Tier III-krav som mål kunde förhindrad mängd utsläppt NOX beräknas och med hjälp av bildad rökgasmängd vid användande med och utan system kunde en uppfattning fås om hur systemen påverkar fartygets emissioner. Beräkningar valdes att göras över en uppskattad livslängd för ett fartyg, 20 år. Vidare valdes de ekonomiska kostnaderna för systemen att slås samman med inköpspriset för systemen. Slutsatser som kunde tas från studien var bland annat att SCR är det system vars sammanräknade kostnad är lägst vid drift. EGR är en teknik som utöver att klara Tier III-kraven även medför en minskning av en del andra miljöförorenande ämnen. Studien antyder att EGR är det bättre systemet ur emission synpunkt och SCR är det bättre systemet sett till ekonomi. / This case study examines how two marine systems used for reduction of nitrogen oxides from exhaust gases, EGR and SCR, performs in terms of emissions and economic impact. A commonly used two-stroke diesel engine was chosen to be, in theory, equipped with each system. By using a calculation program, CEAS, calculations based on different running conditions were possible and thereby obtain relevant data. With the given consumption of chemicals for each system and the consumption of fuel, costs were able to be calculated after price data was retrieved. With IMO’s tier III regulation as the limit, the inhibited amount of released NOX could be calculated. By using data of produced amounts of exhaust gases, with and without the systems, an estimate could be made on how the systems affect the ship emissions. Calculations were based on an approximation of a vessels lifespan, 20 years. Furthermore, the economic cost for each system was added with the purchase price of each system. Conclusions that could be drawn from the study were, amongst other things, that SCR was the system with the lowest operational cost. EGR does, besides being able to manage the Tier III-requirement, also manage to reduce some other environmental hazardous substances. The study implies that EGR is the better system when viewed in terms of emissions and SCR is the better system when viewed in terms of economy.

L’arthrose (OA) est une maladie dégénérative très répondue touchant les articulations. Elle est caractérisée par la destruction progressive du cartilage articulaire, l’inflammation de la membrane synoviale et le remodelage de l’os sous chondral. L’étiologie de cette maladie n’est pas encore bien définie. Plusieurs études ont été menées pour élucider les mécanismes moléculaires et cellulaires impliqués dans le développement de l’OA. Les effets protecteurs du récepteur activé par les proliférateurs de peroxysomes gamma (PPARγ) dans l'OA sont bien documentés. Il a été démontré que PPARγ possède des propriétés anti-inflammatoires et anti-cataboliques. Aussi, plusieurs stimuli ont été impliqués dans la régulation de l’expression de PPARγ dans différents types cellulaires. Cependant, les mécanismes exacts responsables de cette régulation ainsi que le profil de l’expression de ce récepteur au cours de la progression de l’OA ne sont pas bien connus. Dans la première partie de nos travaux, nous avons essayé d’élucider les mécanismes impliqués dans l’altération de l’expression de PPARγ dans cette maladie. Nos résultats ont confirmé l’implication de l’interleukine-1β (IL-1β), une cytokine pro-inflammatoire, dans la réduction de l’expression de PPARγ au niveau des chondrocytes du cartilage articulaire. Cet effet coïncide avec l'induction de l’expression du facteur de transcription à réponse précoce de type 1 (Egr-1). En plus, la diminution de l'expression de PPARγ a été associée au recrutement d'Egr-1 et la réduction concomitante de la liaison de Sp1 au niveau du promoteur de PPARγ. Dans la deuxième partie de nos travaux, nous avons évalué le profil d’expression de ce récepteur dans le cartilage au cours de la progression de cette maladie. Le cochon d’inde avec OA spontanée et le chien avec OA induite par rupture du ligament croisé antérieur (ACLT) deux modèles animaux d’OA ont été utilisés pour suivre l’expression des trois isoformes de PPARs : PPAR alpha (α), PPAR béta (β) et PPAR gamma (γ) ainsi que la prostaglandine D synthase hématopoïétique (H-PGDS) et la prostaglandine D synthase de type lipocaline (L-PGDS) deux enzymes impliquées dans la production de l’agoniste naturel de PPARγ, la 15-Deoxy-delta(12,14)-prostaglandine J(2) (15d-PGJ2). Nos résultats ont démontré des changements dans l’expression de PPARγ et la L-PGDS. En revanche, l’expression de PPARα, PPARβ et H-PGDS est restée stable au fil du temps. La diminution de l’expression de PPARγ dans le cartilage articulaire semble contribuer au développement de l’OA dans les deux modèles animaux. En effet, le traitement des chondrocytes par de siRNA dirigé contre PPARγ a favorisé la production des médiateurs arthrosiques tels que l'oxyde nitrique (NO) et la métalloprotéase matricielle de type 13 (MMP-13), confirmant ainsi le rôle anti-arthrosique de ce récepteur. Contrairement à ce dernier, le niveau d'expression de la L-PGDS a augmenté au cours de la progression de cette maladie. La surexpression de la L-PGDS au niveau des chondrocytes humains a été associée à la diminution de la production de ces médiateurs arthrosiques, suggérant son implication dans un processus de tentative de réparation. En conclusion, l’ensemble de nos résultats suggèrent que la modulation du niveau d’expression de PPARγ, de la L-PGDS et d’Egr-1 au niveau du cartilage articulaire pourrait constituer une voie thérapeutique potentielle dans le traitement de l’OA et probablement d’autres formes d'arthrite. / Osteoarthritis (OA) is the most common degenerative joint disease. It is characterised by progressive destruction of articular cartilage, synovial inflammation and subchondral bone remodelling. The complete etiology of OA is still not well defined. Several studies have been carried out to elucidate the molecular and cellular mechanisms involved in OA development. The protective effects of Peroxisome proliferator-activated receptor gamma (PPARγ) in OA have been well documented. It has been demonstrated that PPARγ exhibit anti-inflammatory and anti-catabolic properties. Although many stimuli have been reported to regulate the expression of PPARγ in several cell types. However, little information is available on the exact mechanisms that govern its regulation as well as the expression profile of this recepteur during the course of the disease. In the first part of this work, we tried to elucidate the mechanisms involved in the alteration of PPARγ expression in OA. Our findings confirm that interleukin-1 beta (IL-1β), a proinflammatory cytokine, down regulate the expression of PPARγ in articular chondrocytes. This effect coincided with the induction of early growth response protein-1 (Egr-1) expression. In addition, down regulation of PPARγ expression was associated with Egr-1 recruitment to and concomitant reduction in Sp1 occupancy at PPARγ promoter. In the second part of this work, we evaluated the expression profile of this receptor in cartilage during the progression of OA. Spontaneous Hartley guinea pig model and anterior cruciate ligament transection (ACLT) dog model were used to follow the expression of three isoforms of PPARs: PPAR alpha (α), PPAR beta (β) and PPAR gamma (γ) as well as hematopoietic prostaglandin D synthase (H-PGDS) and lipocalin-type prostaglandin D synthase (L-PGDS) two enzymes involved in the production of the natural agonist PAARγ, 15-Deoxy-delta(12,14)-prostaglandin J(2) (15d PGJ2). Our reultats showed changes in the expression of PPARγ and L-PGDS. In contrast, the level of PPARα, PPARβ and H-PGDS was constant over time. The decrease in PPARγ levels in articular chondrocytes suggest that it may be a contributing factor in OA development in both animal models used in this study. Furthermore, siRNA silencing of PPARγ resulted in an enhanced production of osteoarthric mediators such as matrix metalloproteinase-13 (MMP-13) and nitric oxide (NO). Thus, confirming the anti-arthritic role of this receptor. In contrast, unlike the later, there was an increase in the expression level of L-PGDS during disease progression. The overexpression of L-PGDS in human chondrocytes was associated with reduced production of these osteoarthric mediators, suggesting its involvement in repair process. In summary, our data suggest that the modulation of PPARγ, L-PGDS and Egr-1 expression levels in articular cartilage may be a potential therapeutic approach in the treatment of OA and probably other forms of arthritis.

Les anticorps monoclonaux (AcM) anti-CD20 sont essentiels pour le traitement du lymphome non hodgkinien et de la leucémie lymphoïde chronique (LLC). Les AcM agissent soit en activant directement la signalisation apoptotique dans les cellules cibles, soit via le système immunitaire. Dans une étude préclinique, nous avons montré que le traitement avec AcM anti-CD20, rituximab et GA101, induit l'expression de la protéine early growth response 1 (EGR-1) (Dalle et al., 2011). EGR-1 est un facteur de transcription régulé par le calcium (Ca2+) et CD20 est impliqué dans la régulation du flux calcique transmembranaire. Nous avons donc étudié le rôle d'EGR-1 et du flux Ca2+ dans l'activité cytotoxique des AcM anti-CD20. Nous avons montré qu'EGR-1 est rapidement induit suite à l'exposition au rituximab et à GA101. La baisse de l'expression d'EGR-1 par shRNA a supprimé l'effet cytotoxique du GA101 à la fois in vitro et in vivo, indiquant qu'EGR-1 est requis pour la mort cellulaire médiée par CD20. De plus, la surexpression d'EGR-1 augmente la sensibilité au GA101 in vitro et in vivo. En outre, nos résultats indiquent que les AcM anti-CD20 induisent un flux Ca2+. Le blocage du flux Ca2+ par inhibiteurs de canaux calciques (ICC) a aboli l'induction d'EGR-1 ainsi que l'efficacité du GA101 in vivo et ex vivo dans des échantillons de LLC. Plus important, nos données indiquent que les patients recevant des ICC ont une moins bonne réponse au traitement par les AcM anti-CD20. En conclusion, nous avons identifié EGR-1 comme potentiel biomarqueur pour prédire la réponse à la thérapie anti-CD20 et démontré que les ICC ont un impact négatif sur l'efficacité des AcM anti-CD20 chez les patients / Anti-CD20 monoclonal antibodies (mAbs) are an essential component of the treatment of patients with non-Hodgkin's lymphoma and chronic lymphocytic leukemia (CLL). They mediate their antitumor effects by activating the immune system or by direct apoptotic signaling in target cells. In a previous preclinical study, we showed that treatment with anti-CD20 mAbs, rituximab and GA101, resulted in upregulated expression of early growth factor 1 (EGR-1) (Dalle et al. 2011). EGR-1 is a calcium (Ca2+) regulated transcription factor and CD20 is hypothesized to regulate transmembrane Ca2+ flux. Therefore, we aimed to assess the role of EGR-1 and Ca2+ flux in the cytotoxic activity of anti-CD20 mAbs. We have shown that EGR-1 expression is rapidly upregulated in CD20+ cells following rituximab and GA101 exposure. Decreasing EGR-1 expression by shRNA abolishes the direct cytotoxic effect of GA101 both in vitro and in vivo, indicating that EGR-1 is required for CD20-mediated cell death. Additionally, the overexpression of EGR-1 enhances the cytotoxic activity of GA101 both in vitro and in vivo. Furthermore, our results indicate that anti-CD20 mAbs induce calcium influx. Blocking the Ca2+ flux with calcium channel blockers (CCB) abolishes EGR-1 induction and impaires the GA101 efficacy in vivo and ex vivo in CLL blood samples. More importantly, our data indicate that patients receiving CCBs and anti-CD20 therapy have worst progression free survival and overall survival. In conclusion we have identified EGR-1 as a potential biomarker to predict response to anti-CD20 therapy. We demonstrated that co-treatement with CCBs negatively impacts the outcome of patients receiving anti-CD20 mAbs

Resumen de la tesis A pesar del desarrollo en el post-tratamiento de los NOx en motores Diesel, el EGR (Recirculación de los Gases de Escape) continúa siendo una solución efectiva desde el punto de vista técnico y económico para cumplir las normativas anti-contaminantes presentes y futuras. Con el uso generalizado de los filtros de partículas, las desventajas tradicionales de los sistemas de EGR de baja presión, esto es, la durabilidad del compresor y el intercooler , se han reducido. Además, los sistemas de EGR de baja presión han adquirido un considerable interés recientemente por permitir llevar a cabo altas tasas de EGR manteniendo bajas temperaturas de admisión. Si bien la bibliografía acerca de los efectos de la recirculación de gases de escape en la combustión y las emisiones de los motores Diesel es particularmente extensa, poco hay publicado acerca de los efectos del EGR en los procesos de renovación de la carga, especialmente cuando se emplean circuitos de EGR de baja presión. Por este motivo, en esta tesis se examinan los efectos de ambos sistemas de EGR (alta y baja presión) en los procesos de renovación de la carga y en la sobrealimentación. En lo que respecta al impacto de la arquitectura del sistema de EGR en el proceso de renovación de la carga, el estudio se centrará tres factores principales: la capacidad de ambas arquitecturas para introducir masa en los cilindros, evaluada a partir del gasto de aire y la tasa de EGR, la eficiencia del proceso de renovación de la carga, determinada por el trabajo de bombeo, y finalmente, la capacidad de ambos sistemas de distribuir homogéneamente el EGR entre cilindros. En lo concerniente a los efectos de la configuración del sistema de EGR en la sobrealimentación, en este trabajo se evalúan los efectos de los diferentes gastos a través de turbina y compresor, el acoplamiento que aparece entre los sistemas de EGR y TGV, y algunas estrategias de control del EGR y la turbina. Puesto que la condensación de es / Plá Moreno, B. (2009). Análisis del proceso de la recirculación de los gases de escape de baja presión en motores Diesel sobrealimentados [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/4782 / Palancia

No description available.

Une augmentation de la génération des dérivés réactifs de l’oxygène (DRO), tels que le peroxyde d’hydrogène (H2O2), joue un rôle clé dans la pathophysiologie des maladies cardiovasculaires (MCV). La croissance et la prolifération excessives des cellules musculaires lisses vasculaires (CMLV) ont été suggérées comme étant les mécanismes à la base de la dysfonction vasculaire. Une implication potentielle du facteur de transcription Early growth response protein-1 (Egr-1) dans le développement des dommages vasculaires a été proposée. Des études ont démontré que le H2O2 augmente l’expression de l’Egr-1 dans les CMLV. Cependant, les voies de signalisation intracellulaire menant à l’expression de l’Egr-1 en réponse au H2O2 restent à établir. L’objectif de cette étude vise à examiner les différentes voies de signalisation impliquées dans l’expression de l’Egr-1 induite par le H2O2 dans les CMLV. Le H2O2 augmente l’expression de l’Egr-1 en fonction du temps et de la dose dans les CMLV A10. Le blocage pharmacologique des tyrosines kinases insulin-like growth factor-1 receptor (IGF-1R) et c-Src, par AG1024 et PP2 respectivement, atténue l’expression de l’Egr-1 induite par le H2O2, alors que l’AG1478, un inhibiteur de l’epidermal growth factor receptor (EGFR), et le PP3, l’analogue inactif du PP2, n’ont aucun effet sur l’expression de l’Egr-1. Le blocage pharmacologique de l’extracellular signal-regulated kinase 1/2 (ERK1/2), par UO126, et de la protéine kinase C (PKC), par rottlerin et rö-31-8220, diminue l’expression de l’Egr-1 induite par le H2O2. En résumé, nos résultats suggèrent que le H2O2 déclenche l’expression de l’Egr-1 via l’IGF-1R, la kinase c-Src, l’ERK1/2 et la PKC dans les CMLV. / Increased generation of reactive oxygen species (ROS), such as hydrogen peroxide (H2O2), plays a key role in the pathophysiology of cardiovascular diseases (CVD). Excessive growth and proliferation of vascular smooth muscle cells (VSMCs) has been suggested as an important contributor of vascular dysfunction. A potential involvement of early growth response protein-1 (Egr-1), a zinc-finger transcription factor, in the development of vascular injury has been proposed. Recent studies have shown that H2O2 increases Egr-1 expression in VSMCs. However, signaling events leading to H2O2-induced Egr-1 expression are not fully understood. Therefore, this study aims to examine the signaling pathways implicated in H2O2-induced Egr-1 expression in VSMC. H2O2 increased Egr-1 expression in a time and dose-dependent fashion in A10 VSMC. Pharmacological blockade of tyrosine kinases insulin-like growth factor-1 receptor (IGF-1R) and c-Src, by AG1024 and PP2 respectively, attenuated H2O2-induced Egr-1 expression, while AG1478, an epidermal growth factor receptor (EGFR) inhibitor, and PP3, the inactive analogue of PP2, have no effect on Egr-1 expression. Pharmacological blockade of extracellular signal-regulated kinase 1/2 (ERK1/2), by UO126, and proteine kinase C (PKC), by rottlerin and rö-31-8220, decreased H2O2-induced Egr-1 expression. In summary, our results suggest that H2O2 triggers Egr-1 expression through IGF-1R, c-Src, ERK1/2 and PKC in VSMC.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Turbocharger performance maps are vital components used in an engine-turbocharger matching process, a 1D engine performance development stage and a day-to-day operation of a turbocharged vehicle. The main aim of this thesis is the investigation of the turbocharger compressor performance when operating with an alternative to air substitute gas. This occurs, for instance, when turbocharging and low pressure exhaust gas recirculation (LP EGR) technologies are combined. To conduct the experimental study of the turbocharger performance with substitute gas a steady-state turbocharger test facility with a compressor closed-loop mode has been designed and built within this thesis by the author. Also, for the most accurate performance map determination an uncertainty analysis of a selected turbocharger performance map and an extensive study on surge have also been carried out. The sensor based uncertainty analysis has been a key aspect to help to understand the links between the accuracy of measured quantities and the overall uncertainty of the performance parameters. Such knowledge allowed for a selection of sensors targeting the most accurate data measurement. While investigating the uncertainty of the turbocharger performance maps heat transfer related efficiency uncertainty was also studied. Namely, a series of a semi-adiabatic tests were performed in the low turbocharger speed region which highlighted the issues related to a work and heat transfer separation and uncertainty of the extrapolated performance data. Also, a contribution to the turbocharger heat transfer modelling has been made by supporting the in-house lumped capacitance thermal node model with the 3D CHT (conjugate heat transfer) simulations [1, 2]. Finally, a study of a literature based compressor heat estimation method was performed as an alternative way of separating work and heat transfer (with low speed adiabatic mapping). The experimental surge study was conducted in phases and included the analysis and comparison of the low and high frequency pressure data gathered at various locations downstream and upstream from the compressor and temperature data collected at close distance from impeller eye. It has been concluded that the post-compressor located pressure measurement is preferable (than the pre-compressor pressure measurement) as the FFT (Fast Fourier Transform) magnitude of the peak frequency associated with surge is independent on the distance of the sensor from the compressor. The useage of the temperature sensor installed at the closest distance from the compressor entry allowed an observation of the near surge temperature rise (a result of the air recirculation). However, due to the inconsistent rate of the temperature rise across the various speed lines along with the poor response it offers no benefit from the surge avoidance point of view. The comparison of the available surge metrics revealed that the resultant surge lines were drawn at different operating points especially at the higher turbocharger speed lines where the surge development investigated by the rise of the low frequency FFT magnitude peaks was much more visible. The experimental tests performed in steady-state and pulsating flow conditions have indicated larger surge margin availability for the latter case [3]. Development of a turbocharger rig and gaining the confidence in turbocharger performance map generation allowed the author to carry out the investigation over compressor performance with a substitute gas. The study covered two cases of homogeneous and non-homogeneous gas introduction representing a well and a poorly mixed gases respectively. The substitute gas included various mixtures of CO2 and air and pure CO2. It has been highlighted that when comparing turbomachinery performance maps working with substitute gas non-dimensional speed and mass flow parameters shall be introduced. These parameters allow for the map corrections with respect to individual gas constant (R) and ratio of specific heats (γ). The experimentally obtained compressor performance maps with low CO2 concentration in CO2-air mixtures (3%, 5% and 10%) were successfully corrected with the use of non-dimensional speed and mass flow parameters. However, the compressor performance map obtained for the pure CO2 has revealed significant offsets in pressure ratio, efficiency, surge and choke flow locations. This is due to a significantly different γ. In the attempt of the further performance correction a method proposed by Roberts and Sjolander has been followed. As a result of such, a poor match between the measured and predicted values of compressor efficiency was achieved (n exponent = 0.8). A closer correlation was obtained if the n exponent was made a speed dependent variable. This observation has suggested that the measurement of compressor efficiency was affected by the heat transfer between the uninsulated turbomachinery components. Due to the time limitations this assertion has not been investigated experimentally. Realising this limitation, therefore, a series of adiabatic CFD simulations have been performed instead. These simulations have shown that for the case of pure CO2 a reasonable match between the simulated and predicted values of efficiency and pressure ratio was achieved. The experimental and numerical comparison of the compressor performance for homogeneously and non-homogeneously introduced substitute gas did not show any significant compressor performance changes. Finally, experimental study of selected configurations of the intake pipework and EGR mixing valve has shown that complex flow regimes can be developed within the LP EGR system affecting the compressor’s surge margin, efficiency and width of the map. This demonstrates that the aerodynamic disturbances of an EGR mixing valve may have the largest influence on the compressor map compared to all other factors.

<p>Because of new emission and on board diagnostics legislations, heavy truck manufacturers are facing new challenges when it comes to improving the engines and the control software. Accurate and real time executable engine models are essential in this work. One successful way of lowering the NOx emissions is to use Exhaust Gas Recirculation (EGR). The objective of this thesis is to create a mean value model for Scania's next generation EGR system consisting of a poppet valve and a two stage cooler. The model will be used to extend an existing mean value engine model. Two models of different complexity for the EGR system have been validated with sufficient accuracy. Validation was performed during static test bed conditions. The resulting flow models have mean relative errors of 5.0% and 9.1% respectively. The temperature model suggested has a mean relative error of 0.77%.</p>