O Tumor Odontogênico Queratocístico (TOQC) é considerado uma entidade com alta taxa de recidiva e agressividade local, apresentando também frequente associação com a Síndrome do Carcinoma Basocelular Neviode (SCBCN), por isso a patogêneses de este tumor tem sido intensamente estudada. A transformação e proliferação de células neoplásicas normalmente envolvem a desregulação de vias de sinalização que participam do desenvolvimento embrionário normal, principalmente a via Sonic Hedgehog (Shh). A expressão de certas proteínas presentes nesta via foi detectada em vários tumores odontogênicos, sugerindo que desempenha um papel importante nas interações epiteliais e na proliferação de células tumorais. Embora o papel da via de sinalização Shh não esteja bem estabelecida no desenvolvimento de TOQCs, sugere-se que sua ativação pode ser correlacionada com o comportamento clínico agressivo destas lesões. O objetivo deste estudo foi avaliar a expressão imunoistoquímica das proteínas da via de sinalização Shh em TOQCs esporádicos e associados a SCBCN, além de comparar a sua expressão entre lesões recorrentes e não recorrentes. Para isso foi realizado um estudo retrospectivo onde as características clinicopatológicas de 62 pacientes foram avaliadas, a expressão imunoistoquímica das proteínas Shh, Ptch1, Ptch2, Smo, Gli1, Gli2 e Gli3 foi analisada em todas as amostras, comparando TOQCs sindrômicos (29 lesões) e TOQCs esporádicos (57 lesões), assim como sua respectiva recorrência. Com este estudo foi possível observar que as proteínas Shh, Smo e Gli1 revelaram aumento da expressão em TOQCs associados a SCBCN, em comparação com tumores esporádicos. Shh mostrou expressão citoplasmática intermédia dentro da camada basal em tumores sindrômicos, Smo por sua vez revelou forte expressão nuclear e citoplasmática nas camada basal e suprabasal de tumores sindrômicos, enquanto que a expressão de Gli1 foi mais elevada apenas no citoplasma de TOQCs associados a síndrome em comparação com tumores esporádicos. No que diz respeito a sua recorrência, as proteínas Ptch1 e Gli2 mostraram maior expressão em TOQCs esporádicos e recorrentes, enquanto que a expressão Gli1 foi mais relevante nos tumores recorrentes e associados a SCBCN. Os nossos resultados sugerem que a maior expressão das proteínas Shh, Smo e Gli1 em TOQCs pode contribuir para o diagnóstico precoce de lesões associadas com a SCBCN. Da mesma forma, as proteínas Ptch1 e Gli2 pode predizer o risco de recorrência de TOQCs esporádicos, enquanto Gli1 sugere uma potencial associação de recorrência em tumores sindrômicos. / Keratocystic Odontogenic Tumor (KCOT) is considered an entity of high recurrence rates and local aggressiveness, also often presenting association with Nevoid basal cell carcinoma syndrome (NBCCS), and the pathogenesis of this tumor has been therefore intensively studied. The transformation and proliferation of neoplastic cells usually involve deregulation of signaling pathways participating in normal embryonic development, mainly via Sonic Hedgehog (Shh). The expression of certain proteins of this pathway has been detected in several odontogenic tumors, suggesting that plays an important role in epithelial interactions and proliferation of tumor cells. Although the role of Shh signaling pathway is not well established in the development of KCOTs it has been suggested that its activation can be correlated to the aggressive clinical behavior of these lesions. The aim of this study is therefore to evaluate the immunohistochemical expression of proteins of Shh signaling pathway in sporadic KCOTs and associated with NBCCS and to compare their expression between recurring and non-recurring lesions.thus, a retrospective study was performed where the clinicopathological features of 62 patients were evaluated, the immunohistochemical expression of the Shh, Ptch1, Ptch2, Smo, Gli1, Gli2 and Gli3 protein, was analyzed in all samples, comparing syndromic KCOTs ( 29 lesions) and sporadic KCOTs (57 lesions), and also their respective recurrence. The results showed that the expression of Shh, Smo and Gli1 proteins was increased in KCOTs associated with NBCCS compared to sporadic tumors. Shh showed intermediate cytoplasmic expression within the basal layer syndromic tumors, Smo in turn showed strong nuclear expression and cytoplasmic in basal and suprabasal layers of syndromic tumors, while Gli1 cytoplasm expression was higher only in KCOTs associated syndrome compared with sporadic tumors. Regarding recurrent tumors, Ptch1 and Gli2 proteins showed higher expression in sporadic and recurrent KCOTs, while Gli1 expression was more significant in recurrent tumors and associated NBCCS. Our results suggest that increased expression of Shh, Smo and Gli1 proteins in KCOTs can contribute to early diagnosis of KCOTs associated with the NBCCS. Likewise, Ptch1 and Gli2 proteins can predict the risk of recurrence of sporadic KCOTs, while Gli1 suggest a potential association to recurrence into syndromic tumors.

O Tumor Odontogênico Queratocístico (TOQC) é considerado uma entidade com alta taxa de recidiva e agressividade local, apresentando também frequente associação com a Síndrome do Carcinoma Basocelular Neviode (SCBCN), por isso a patogêneses de este tumor tem sido intensamente estudada. A transformação e proliferação de células neoplásicas normalmente envolvem a desregulação de vias de sinalização que participam do desenvolvimento embrionário normal, principalmente a via Sonic Hedgehog (Shh). A expressão de certas proteínas presentes nesta via foi detectada em vários tumores odontogênicos, sugerindo que desempenha um papel importante nas interações epiteliais e na proliferação de células tumorais. Embora o papel da via de sinalização Shh não esteja bem estabelecida no desenvolvimento de TOQCs, sugere-se que sua ativação pode ser correlacionada com o comportamento clínico agressivo destas lesões. O objetivo deste estudo foi avaliar a expressão imunoistoquímica das proteínas da via de sinalização Shh em TOQCs esporádicos e associados a SCBCN, além de comparar a sua expressão entre lesões recorrentes e não recorrentes. Para isso foi realizado um estudo retrospectivo onde as características clinicopatológicas de 62 pacientes foram avaliadas, a expressão imunoistoquímica das proteínas Shh, Ptch1, Ptch2, Smo, Gli1, Gli2 e Gli3 foi analisada em todas as amostras, comparando TOQCs sindrômicos (29 lesões) e TOQCs esporádicos (57 lesões), assim como sua respectiva recorrência. Com este estudo foi possível observar que as proteínas Shh, Smo e Gli1 revelaram aumento da expressão em TOQCs associados a SCBCN, em comparação com tumores esporádicos. Shh mostrou expressão citoplasmática intermédia dentro da camada basal em tumores sindrômicos, Smo por sua vez revelou forte expressão nuclear e citoplasmática nas camada basal e suprabasal de tumores sindrômicos, enquanto que a expressão de Gli1 foi mais elevada apenas no citoplasma de TOQCs associados a síndrome em comparação com tumores esporádicos. No que diz respeito a sua recorrência, as proteínas Ptch1 e Gli2 mostraram maior expressão em TOQCs esporádicos e recorrentes, enquanto que a expressão Gli1 foi mais relevante nos tumores recorrentes e associados a SCBCN. Os nossos resultados sugerem que a maior expressão das proteínas Shh, Smo e Gli1 em TOQCs pode contribuir para o diagnóstico precoce de lesões associadas com a SCBCN. Da mesma forma, as proteínas Ptch1 e Gli2 pode predizer o risco de recorrência de TOQCs esporádicos, enquanto Gli1 sugere uma potencial associação de recorrência em tumores sindrômicos. / Keratocystic Odontogenic Tumor (KCOT) is considered an entity of high recurrence rates and local aggressiveness, also often presenting association with Nevoid basal cell carcinoma syndrome (NBCCS), and the pathogenesis of this tumor has been therefore intensively studied. The transformation and proliferation of neoplastic cells usually involve deregulation of signaling pathways participating in normal embryonic development, mainly via Sonic Hedgehog (Shh). The expression of certain proteins of this pathway has been detected in several odontogenic tumors, suggesting that plays an important role in epithelial interactions and proliferation of tumor cells. Although the role of Shh signaling pathway is not well established in the development of KCOTs it has been suggested that its activation can be correlated to the aggressive clinical behavior of these lesions. The aim of this study is therefore to evaluate the immunohistochemical expression of proteins of Shh signaling pathway in sporadic KCOTs and associated with NBCCS and to compare their expression between recurring and non-recurring lesions.thus, a retrospective study was performed where the clinicopathological features of 62 patients were evaluated, the immunohistochemical expression of the Shh, Ptch1, Ptch2, Smo, Gli1, Gli2 and Gli3 protein, was analyzed in all samples, comparing syndromic KCOTs ( 29 lesions) and sporadic KCOTs (57 lesions), and also their respective recurrence. The results showed that the expression of Shh, Smo and Gli1 proteins was increased in KCOTs associated with NBCCS compared to sporadic tumors. Shh showed intermediate cytoplasmic expression within the basal layer syndromic tumors, Smo in turn showed strong nuclear expression and cytoplasmic in basal and suprabasal layers of syndromic tumors, while Gli1 cytoplasm expression was higher only in KCOTs associated syndrome compared with sporadic tumors. Regarding recurrent tumors, Ptch1 and Gli2 proteins showed higher expression in sporadic and recurrent KCOTs, while Gli1 expression was more significant in recurrent tumors and associated NBCCS. Our results suggest that increased expression of Shh, Smo and Gli1 proteins in KCOTs can contribute to early diagnosis of KCOTs associated with the NBCCS. Likewise, Ptch1 and Gli2 proteins can predict the risk of recurrence of sporadic KCOTs, while Gli1 suggest a potential association to recurrence into syndromic tumors.

Sonic boom annoyance is an important technical showstopper for commercial supersonic aircraft operations. It has been proposed that aircraft can be shaped to alleviate sonic boom. Choosing the right aircraft shape reflecting the design requirements is a fundamental and most important step that is usually over simplified in the conceptual stages of design by resorting to a qualitative selection of a baseline configuration based on historical designs and designers perspective. Final aircraft designs are attempted by minor shape modifications to this baseline configuration. This procedure may not yield large improvements in the objectives, especially when the baseline is chosen without a rigorous analysis procedure. Traditional analyses and implementations tend to have a complex algorithmic flow, tight coupling between tools used and computational limitations. Some of these shortcomings are overcome in this study and a diverse mix of tools is seamlessly integrated to provide a simple, yet powerful and automatic procedure for sonic boom minimization. A shape optimization procedure for supersonic aircraft design using better geometry generation and improved analysis tools has been successfully demonstrated. The geometry engine provides dynamic reconfiguration and efficient manipulation of various components to yield unstructured watertight geometries. The architecture supports an assimilation of different components and allows configuration changes to be made quickly and efficiently because changes are localized to each component. It also enables an automatic way to combine linear and non-linear analyses tools. It has been shown in this study that varying atmospheric conditions could have a huge impact on the sonic boom annoyance metrics and a quick way of obtaining probability estimates of relevant metrics was demonstrated. The well-accepted theoretical sonic boom minimization equations are generalized to a new form and the relevant equations are derived to yield increased flexibility in aircraft design process. Optimum aircraft shapes are obtained in the conceptual design stages weighing in various conflicting objectives. The unique shape optimization procedure in conjunction with parallel genetic algorithms improves the computational time of the analysis and allows quick exploration of the vast design space. The salient features of the final designs are explained. Future research recommendations are made.

The present thesis is a contribution to unravel the molecular mechanisms that underlie urodele regeneration. Urodele amphibians (newts and salamanders) are among the few vertebrates with the remarkable ability to regenerate lost body appendages, like the limbs and the tail. Urodele tail and limb regeneration occurs via blastemal epimorphic regeneration. A blastema is a mound of progenitor cells that accumulates at the amputation plane and eventually gives rise to the missing structures. It is known today that dedifferentiating muscle fibers at the amputation plane contribute to the blastema cell pool, but how this process occurs on the cellular and molecular level is hardly understood, which is in part due to the lack of molecular methods to test gene function in urodeles. Furthermore, little is known about how coordinated growth and patterning occurs during urodele regeneration, and if the patterning mechanisms in regeneration are related to the ones in development. The goal of this study was to better understand these processes on the molecular level. To address these questions, I first established several methods in our model systems, which are the mexican salamander Ambystoma mexicanum (axolotl) and a cell line derived from the newt Notophthalmus viridescens. In order to monitor gene expression on a cellular level during regeneration, I worked out a good in situ hybridization protocol on axolotl tissue cryosections. To be able to test gene function, I established electroporation conditions to both overexpress genes in the cultured newt cells and to deliver morpholinos into axolotl cells in vivo and newt cells in culture. I demonstrate here that morpholinos are an effective tool to downregulate protein expression in urodele cells in vivo and in culture. Testing the role of two candidate genes in muscle fiber dedifferentiation, the homeobox containing transcription factor Msx1 and Rad, a GTP-binding protein of a new Ras-related protein family, revealed that neither seems to play a major role in muscle dedifferentiation, both in culture and in vivo. In addition to testing gene function I have examined the muscle dedifferentiation process in more detail. I show here that dedifferentiating muscle fiber nuclei undergo morphological changes that are likely due to chromatin remodeling events. I also demonstrate that the axolotl spinal cord expresses embryonic dorsoventral (d/v) patterning markers of the neural tube. The transcription factors Msx1, Pax7 and Pax6 are expressed in their respective d/v domains in both the differentiated and the regenerating axolotl spinal cord. Furthermore, the secreted signaling molecule sonic hedgehog (Shh) is expressed in the floor plate in both the differentiated and the regenerating cord. Using a chemical inhibitor (cyclopamine) and an activator of the hedgehog pathway, I discovered that hedgehog signaling is required for overall tail regeneration. Blocking hedgehog signaling does not only result in d/v patterning defects of the regenerating spinal cord, but it also strongly reduces blastema cell proliferation. In addition, I identified cartilage and putative muscle progenitor cells in the blastema, marked by the expression of the transcription factors Sox9 and Pax7, respectively. Both progenitor populations are reduced in the blastema in the absence of hedgehog signaling. The continuous expression of marker genes for embryonic progenitor cell domains in the mature axolotl may be related to their ability to regenerate.

Le syndrome de Gorlin est une maladie rare caractérisée par de nombreuses anomalies du développement. Ces manifestations cliniques, dues à des mutations d'un acteur essentiel de la voie de signalisation sonic hedgehog, incluent aussi une hyper-radiosensibilité et une forte prédisposition à développer des carcinomes basocellulaires. Etant donné l'implication de défaut de la réparation de l'ADN au niveau des affections liées à l'hyper-radiosensibilité, nous avons décidé d'étudier l'effet des mutations du gène PTCH1 sur la réponse aux dommages de l'ADN afin de mieux comprendre les mécanismes cellulaires et moléculaires conduisant au phénotype Gorlin.Cette étude permet de mettre en évidence une défaillance globale des systèmes de réparation des dommages de l'ADN dans les fibroblastes issus de patients Gorlin par rapport à des fibroblastes normaux. Elle met notamment en exergue un écroulement de la réparation par excision de bases (BER) responsable de la réparation des dommages oxydatifs. / The Gorlin syndrome is a rare genetic disorder characterized by several developmental abnormalities. Due to mutations in PTCH1, a key player of the sonic hedgehog signaling pathway, clinical manifestations also includes hyper-radiosensitivity and an increased predisposition to the development of basal cell carcinomas. Given the implication of DNA repair system defects in hyper-radiosensitivity pathologies, we decided to study the effect of PTCH1 mutations on the DNA damage response in order to better understand the cellular and molecular mechanisms leading to Gorlin's phenotype.This study demonstrate a global failure of the DNA damage repair systems in Gorlin fibroblasts with respect to controls. It highlights in particular the collapse of the base excision repair pathway (BER) responsible for the repair of oxidative DNA damage.

La particularité et l'enjeu du sujet de recherche résident dans la confrontation entre vision urbanistique de l'espace public, approche physique de la mesure acoustique et prise en compte de la perception de l'environnement sonore. Notre étude de l'évaluation d'ambiances sonores urbaines a pour terrain plusieurs espaces publics. Nous problématisons notre réflexion autour de l'appréhension de la perception sonore et de son évaluation en vue d'en souligner certains paramètres influents. La méthodologie est élaborée dans le but de coupler données perceptives et mesures physiques. Ainsi, une première étape d'enquête in situ aboutit à un corpus composé de 174 questionnaires, 513 photographies et 18 entretiens non directifs de groupe. Puis des mesures acoustiques sont pratiquées aux mêmes temporalités. Enfin, une seconde étape d'entretiens individuels approfondis menés avec les 29 participants est complétée par la réalisation de 145 cartes mentales sonores. Cette méthodologie multi-facettes permet de déterminer l'influence de divers paramètres tels que la présence humaine, la naturalité, la minéralité, la saisonnalité et les formes urbaines sur l'évaluation spatiale et sonore au sein d'espaces publics. / The particularity and challenge of this research subject lie in the confrontation between the urbanistic vision of the public space, the physical approach to acoustic measurement and the consideration of how the sonic environment is perceived. Several types of public spaces were used to study the assessment of urban sonic ambiances. We problematize our study of the understanding and assessment of sound perception in order to highlight some of its relevant parameters. The methodology was designed to combine perceptive data and physical measurements. The first stage of in situ investigation thus provided a corpus of 174 questionnaires, 513 photographs and 18 non-directive group interviews. Acoustic measurements were then made at the same temporalities. Finally, a second stage of in-depth individual interviews conducted with the 29 participants was completed with the realization of 145 mental mind maps. This multifaceted methodology helped to determine the influence of several parameters such as human presence, nature, the mineral aspect, seasonality and urban forms on the spatial and sonic assessment in public spaces.

Le syndrome cutané radio-induit (SCR) est une lésion cutanée spécifique secondaire à une irradiation localisée de forte dose, qui se caractérise par des douleurs importantes, des vagues inflammatoires extensives, un défaut de revascularisation et de cicatrisation. De nouvelles stratégies thérapeutiques peuvent être envisagées pour la prise en charge de cette pathologie avec l'émergence récente des cellules souches mésenchymateuses. Ces cellules multipotentes ont des propriétés de transdifférenciation et de sécrétion de facteurs favorisant la régénération tissulaire. L'association de la chirurgie d'exérèse, des greffes de peau autologue et des injections de cellules souches autologues isolées à partir de la moelle osseuse (Bone Marrow Mesenchymal Stem Cells ou BM-MSC) a confirmé ces hypothèses mais leur utilisation reste limitée à des cas de patients isolés.L'objectif de ce travail était d'optimiser la prise en charge du SCR par thérapie cellulaire pour l'étendre aux cas d'accidents de masse ou d'irradiation hétérogène associée.Les cellules souches dérivées du tissu adipeux (ASC pour Adipose tissue derived Stem Cells), plus abondantes que les BM-MSC et présentant des propriétés pro-angiogéniques, anti-apoptotiques et immunomodulatrices équivalentes voire supérieures, ont été choisies pour développer cet outil de thérapie cellulaire. La faisabilité de différentes stratégies thérapeutiques a été évaluée dans ce travail : la constitution de banques cellulaires autologues et allogéniques, une potentialisation des effets des ASC par thérapie génique transitoire et l'utilisation du sécrétome des ASC.La constitution de banques autologues ou allogéniques de cellules souches permet de pallier le délai d'obtention de greffons de taille suffisante en termes de quantité de cellules souches. Cette stratégie évaluée sur un modèle in vivo de miniporc a démontré la pertinence des banques d'ASC autologues mais a également mis en évidence les difficultés liées aux injections d'ASC allogéniques en particulier de type immunologique.La stratégie d'optimisation des ASC par manipulation ex vivo a pour but de potentialiser leurs effets par la sécrétion d'une protéine ad hoc impliquée dans les processus de réparation tissulaire et ainsi, de diminuer la quantité de cellules injectées et donc le temps de culture. La protéine sélectionnée dans ce travail est la protéine Sonic Hedgehog (Shh) décrite comme présentant des propriétés pro-angiogéniques et anti-apoptotiques. L'évaluation d'un protocole de thérapie génique transitoire utilisant des ASC transfectées par une construction plasmidique codant pour Shh (ASC-Shh) a montré la faisabilité de cette stratégie sur un modèle in vivo de miniporc.Les effets pro-angiogéniques de même que les effets du sécrétome des ASC et ASC-Shh sur des fibroblastes irradiés ont confirmé le rôle des facteurs paracrines des ASC dans la survie cellulaire et mis en évidence la potentialisation de leurs effets pro-angiogéniques par Shh. Ainsi l'utilisation du sécrétome des ASC ou ASC-Shh apparaît également comme une stratégie pertinente permettant de s'affranchir de la compatibilité donneur-receveur lors des greffes de cellules souches.Ces différentes techniques basées sur les cellules souches dérivées du tissu adipocytaire représentent donc des stratégies prometteuses pour la prise en charge du syndrome cutané radio-induit. / Cutaneous radiation syndrome (CRS) is a specific skin lesion caused by high dose local irradiation. It is characterized by severe pain, extensive inflammatory waves, incomplete revascularization and wound healing. For the last few years, mesenchymal stem cells (MSC) have become a promising cell source for cell therapy. MSC are multipotent cells which can transdifferentiate and secrete many paracrine factors involved in tissue regeneration, and they may be considered as a new therapeutic strategy for the management of this pathology. This was confirmed by the results of works associating surgical resection, autologous skin graft and autologous bone marrow mesenchymal stem cells (BM-MSC) injections, although the use of the latter remains limited to isolated cases of patients.The aim of this work was to optimize the management of CRS using stem cell therapy in order to extend it to mass casualties or associated heterogeneous irradiation.Adipose tissue derived stem cells (ASC) were chosen to develop cell therapy as they are more abundant than BM-MSC and exhibit higher pro-angiogenic, anti-apoptotic and immunomodulation properties.The feasibility of different therapeutic strategies has been evaluated in this work: the establishment of autologous and allogeneic cell banks, potentiation of ASC effects by transient gene therapy and the use of ASC secretome.The constitution of autologous or allogeneic stem cell banks overcomes the cell expansion delay required to obtain stem cells of clinical quantity. This strategy was evaluated in an in vivo minipig model of CRS and the relevance of autologous ASC banks was shown but this study highlighted difficulties associated with allogeneic injections especially immunological ones.Here is also reported an ASC optimization by ex vivo manipulation that aims to decrease the amount of injected cells and culture time through the secretion of an ad hoc protein involved in tissue repair processes and thus to, decrease the amount of injected cells and therefore the culture time. The protein chosen was Sonic Hedgehog (Shh), known to be involved in pro-angiogenic and anti-apoptotic processes. The evaluation of a transient gene therapy protocol using ASC transfected with a plasmid construct encoding Shh (ASC-Shh) confirmed the feasibility of this strategy in the same minipig model of CRS.The pro-angiogenic effects as well as other effects of ASC and ASC-Shh secretome on irradiated fibroblasts have confirmed the role of ASC paracrine factors in cell survival and demonstrated potentiation of their pro-angiogenic effects by Shh. Thus the use of ASC or ASC-Shh secretome also appears as a relevant strategy to overcome the donor-recipient compatibility during stem cell transplants.These techniques based on adipose tissue derived stem cells represent promising strategies for the management of cutaneous radiation syndrome.

Les vésicules extracellulaires (VE), incluant exosomes et microparticules (MP), vecteurs d’information biologique, peuvent moduler la fonction de cellules cibles. Une élévation du taux de VE circulantes est observée dans les pathologies cardiovasculaires dont l’obésité est l’un des facteurs de risque majeur. Cependant, il existe peu de données concernant la production de VE adipocytaires et leur capacité à moduler le métabolisme des adipocytes. Tout d’abord, nous avons caractérisé de manière morphologique et biochimique les MP et les exosomes adipocytaires. Nous montrons une production accrue de ces VE dans un contexte d’obésité murine. L’analyse protéomique des VE adipocytaires révèle un enrichissement spécifique des MP et des exosomes en protéines clé du métabolisme énergétique et de l’inflammation, respectivement. Dans une seconde partie, nous avons étudié l’effet de MP lymphocytaires portant le morphogène Hedgehog (MPHh+) sur la différenciation adipocytaire. A l’instar d’une activation classique de la voie de signalisation Hh, les MPHh+ inhibent l’adipogenèse. Bien que dépendant du récepteur Smoothened (Smo), cet effet inhibiteur est indépendant des facteurs de transcription Gli. Nous montrons que les MPHh+ activent un axe anti-adipogénique Smo/Lkb1/Ampk pouvant être stimulé par un nouvel agoniste de Smo, le GSA-10. Nos résultats démontrent, d’une part, la capacité des adipocytes à sécréter des VE, et d’autre part, le potentiel fonctionnel des MPHh+ à inhiber l’adipogenèse par une voie de signalisation Hhnon-canonique. Les VE pourraient contribuer aux dysfonctions métaboliques associées à l’obésité en véhiculant des messages métaboliques à l’échelle de l’organisme. / Extracellular vesicles (EV), including microparticles (MP) and exosomes, are able to modulate target cell function through exchange or transfer of biological material. Although EV are present in the blood of healthy individuals, an elevated quantity of circulating EV is associated with cardiovascular diseases, which obesity is a major cardiovascular risk factor. Nevertheless, few studies have reported the ability of adipocytes to release EV and their implication in adipose tissue metabolism. First of all, we could determine morphological and biochemical features of adipocyte-derived exosomes and MP through a combination of methods. We were able to demonstrate an increase in adipocyte EV production in a murine model of obesity. Proteomic analysis of adipocyte EV further revealed a specific enrichment of proteins crucial for glucose and lipid metabolism and related to inflammation in MP and exosomes respectively. We then evaluated the ability of lymphocytes-derived MP harboring the Sonic Hedgehog morphogen to control adipocyte differentiation. Activation of the Hedgehog canonical pathway inhibited adipogenesis, as did MPHh+. Surprisingly, although Smo dependent, inhibitory potential of such MP did not involve the Gli transcription factors. We show that MPHh+ inhibit adipocyte differentiation through a Smo/Lkb1/Ampk axis as does a new agonist of Smo, GSA-10. Our results demonstrate, on one hand, the ability of adipocyte to release EV and on the other hand, the capacity of MPHh+ to control adipogenesis through a non-canonical Hh signaling pathway. In conclusion, EV might contribute to obesity related metabolic dysfunctions through systemic regulation of metabolic pathways.

The present thesis is a contribution to unravel the molecular mechanisms that underlie urodele regeneration. Urodele amphibians (newts and salamanders) are among the few vertebrates with the remarkable ability to regenerate lost body appendages, like the limbs and the tail. Urodele tail and limb regeneration occurs via blastemal epimorphic regeneration. A blastema is a mound of progenitor cells that accumulates at the amputation plane and eventually gives rise to the missing structures. It is known today that dedifferentiating muscle fibers at the amputation plane contribute to the blastema cell pool, but how this process occurs on the cellular and molecular level is hardly understood, which is in part due to the lack of molecular methods to test gene function in urodeles. Furthermore, little is known about how coordinated growth and patterning occurs during urodele regeneration, and if the patterning mechanisms in regeneration are related to the ones in development. The goal of this study was to better understand these processes on the molecular level. To address these questions, I first established several methods in our model systems, which are the mexican salamander Ambystoma mexicanum (axolotl) and a cell line derived from the newt Notophthalmus viridescens. In order to monitor gene expression on a cellular level during regeneration, I worked out a good in situ hybridization protocol on axolotl tissue cryosections. To be able to test gene function, I established electroporation conditions to both overexpress genes in the cultured newt cells and to deliver morpholinos into axolotl cells in vivo and newt cells in culture. I demonstrate here that morpholinos are an effective tool to downregulate protein expression in urodele cells in vivo and in culture. Testing the role of two candidate genes in muscle fiber dedifferentiation, the homeobox containing transcription factor Msx1 and Rad, a GTP-binding protein of a new Ras-related protein family, revealed that neither seems to play a major role in muscle dedifferentiation, both in culture and in vivo. In addition to testing gene function I have examined the muscle dedifferentiation process in more detail. I show here that dedifferentiating muscle fiber nuclei undergo morphological changes that are likely due to chromatin remodeling events. I also demonstrate that the axolotl spinal cord expresses embryonic dorsoventral (d/v) patterning markers of the neural tube. The transcription factors Msx1, Pax7 and Pax6 are expressed in their respective d/v domains in both the differentiated and the regenerating axolotl spinal cord. Furthermore, the secreted signaling molecule sonic hedgehog (Shh) is expressed in the floor plate in both the differentiated and the regenerating cord. Using a chemical inhibitor (cyclopamine) and an activator of the hedgehog pathway, I discovered that hedgehog signaling is required for overall tail regeneration. Blocking hedgehog signaling does not only result in d/v patterning defects of the regenerating spinal cord, but it also strongly reduces blastema cell proliferation. In addition, I identified cartilage and putative muscle progenitor cells in the blastema, marked by the expression of the transcription factors Sox9 and Pax7, respectively. Both progenitor populations are reduced in the blastema in the absence of hedgehog signaling. The continuous expression of marker genes for embryonic progenitor cell domains in the mature axolotl may be related to their ability to regenerate.

En ljudlogotyp är en ljudkomposition som används för att särskilja ett varumärke. Ljudlogotypen ingår i varumärkens strategiska arbete för att skapa sig en bild i konsumenters medvetande. Denna bild kallas varumärkesuppfattning. Syftet med denna studie var att utöka kunskapen om hur musik kan användas i kommunikativt syfte i allmänhet och om hur melodin påverkar uppfattningen av varumärken i synnerhet. En webbenkät genomfördes för att studera om olika typer av melodisk kontur hos en ljudlogotyp kan ge olika effekter på hur ett fiktivt varumärke uppfattas ifråga om varumärkespersonlighet. Deltagare rekryterades via sociala medier. Till undersökningen utformades åtta videoklipp innehållande en ljudlogotyp och en grafisk logotyp. Videoklippen var identiska förutom att den melodiska konturen skilde dem åt. Deltagarna skattade i vilken grad de uppfattade fem olika personlighetsdrag hos den ljudlogotyp de fick höra. Resultaten analyserades statistiskt. Genom undersökningen genererades inget stöd för att typ av melodisk kontur skulle ha någon påverkan på uppfattningen av de fem personlighetsdragen. Lämpliga metoder för undersökningar om ljudlogotyper och varumärkesuppfattning diskuteras. För framtida studier inom området föreslås kvalitativa studier samt studier som undersöker andra musikaliska parametrar. Vidare efterfrågas mer forskning om melodisk kontur. / An audio logo, also called sonic logo or sound logo, is a sound composition utilized to differentiate a brand. A sonic logo is part of a brand’s strategy to create an image in the awareness of consumers. This image is called brand perception. The objective of this study was to expand general knowledge about music’s applicability for communicative purposes and moreover to specifically look at how melody affects brand perception. A web survey was conducted to investigate if different types of melodic contour in an audio logo can have different effects on the perception of brand identity for a fictional brand. Participants were recruited using social media. Eight videos consisting of an audio logo and a graphic logo were designed. The videos were identical apart from their melodic contours. Participants rated the degree to which they perceived five different personality traits for the audio logo they heard. The results were analyzed statistically. Through the survey, no support was generated for an impact from the type of melodic contour on the perception of the five personality traits. Appropriate methods for investigating audio logos and brand perception are discussed. For future research within the field qualitative design is suggested, as well asinvestigations into other musical parameters. Furthermore, additional research into melodic contour is proposed.