Dissertations / Theses: 'Cellular'

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Oshima, Masaya. "Rôles de SOX9 dans la cellule ß pancréatique humaine." Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCB040.

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Le pancréas est une glande amphicrine composée de cellules exocrines et de cellules endocrines. Parmi les cellules endocrines, organisées en îlot de Langerhans, les cellules ß sécrétrices d’insuline en réponse à des stimuli précis, sont essentielles pour l’homéostasie du glucose. Des perturbations tant au niveau qualitatif qu’au niveau quantitatif sont responsables de différentes pathologies telles les diabètes ou certaines formes de tumeurs endocrines. De récentes publications suggèrent que l’état de différenciation de la cellule ß pancréatique mature n’est pas immuable et montrent que le maintien d’un phénotype mature de la cellule est un processus dynamique. Différents modèles de souris mutantes (avec perte ou gain d’un facteur de transcription) montrent une perte de l’identité de la cellule ß. Cette plasticité altère la synthèse, le stockage et la sécrétion d’insuline. En plus de la perte d’identité, caractérisée par la diminution de l’expression de marqueurs de la cellule ß (MAFA, NKX6-1), les cellules ré-expriment des marqueurs de progéniteurs (NGN3, SOX9) : on parle de dédifférenciation. Cette dédifférenciation serait un mécanisme clé dans la diminution de la masse de cellules ß fonctionnelles au cours du diabète de type 2. Le but de ma thèse a été d’étudier le rôle du facteur de transcription SOX9 dans le contexte de la perte d’identité de la cellule ß humaine. SOX9 est exprimé dans les progéniteurs multipotents pancréatiques et joue plusieurs rôles cruciaux au cours du développement de l’organe. Bien qu’un rôle important de SOX9 fut attribué au cours de l’organogénèse du pancréas, il y a de plus en plus de données suggérant qu’il a des rôles additionnels dans le pancréas matures qui semble aussi importants que son rôle au cours du développement. C’est le cas notamment des cellules formant les canaux pancréatiques. D’un autre côté, pour les cellules endocrines, et plus particulièrement les cellules ß, SOX9, normalement absent de la cellule ß saine, est ré-exprimé dans ces cellules dans des conditions pathologiques (diabètes, tumeurs neuroendocrines du pancréas). Une expression ectopique de SOX9 dans les cellules ß induit un phénotype diabétique. Alors qu’il y a de plus en plus d’observation de l’expression de SOX9 dans la cellule ß, il y a très peu de connaissance sur les mécanismes moléculaires et les cibles de ce facteur de transcription dans les cellules ß humaines. Dans un premier temps, nous avons disséqué différents mécanismes impliqués dans l’induction de l’expression de SOX9. Pour cela, nous avons développé des conditions mimant des contextes pathologiques (diabètes, tumeurs neuroendocrines du pancréas VHL) en utilisant les cellules ß humaines EndoCßH1, récemment développées au sein du laboratoire. Dans un deuxième temps, nous avons développé des outils moléculaires afin d’identifier les cibles de SOX9 dans la cellule ß humaine (dominant positif, dominant négatif). Pour finir, nous avons analysé les cibles potentielles de SOX9 dans différentes conditions pathologiques
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Nicholson, Judith. "Cellulore phenomenon : promoting and policing cellular phones in Canada." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ54266.pdf.

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Platt, Steven. "Decentralized cellular networks: Towards blockchain enabled cellular overlays." Doctoral thesis, Universitat Pompeu Fabra, 2021. http://hdl.handle.net/10803/672922.

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This thesis undertakes an investigation into the fit and utility of blockchain technologies within cellular networks. The core of this writing is a new 5G core network blockchain designed to be compatible with, and paired as storage for 3GPP-compliant virtual network functions. Compatibility of the blockchain design is delivered by inheriting a number of behaviors from wireless network operation, including a CSMA/CD mechanism of congestion control; a first for a blockchain design. At the carrier level, a deployment model compatible with ETSI General Autonomous Network Architecture is presented to enable decentralized service overlays. At the network edge, a novel model of transition learning allows fluid roaming of user-equipment across network boundaries. At the conclusion, the theory is combined, to reveal a model of decentralized overlays, which at the user equipment, functions in a manner similar to FM radio. A network channel radio of sorts for decentralized cellular access.
Aquesta tesi realitza una investigació sobre l’us i l’adptabilitat de les tecnologies blockchain en xarxes cel·lulars. El nucli d’aquest treball és una nova blockchain basada en la xarxa 5G dissenyada per ser compatible i utilitzada com a emmagatzematge per a la funció de xarxa virtual compatible amb 3GPP. La compatibilitat del disseny de la blockchain s’ofereix adoptant diversos comportaments de l'operació de xarxa sense fils, inclos un mecanisme CSMA/CD de control de congestió; la primera vegada que s’utilitza per a un disseny de blockchain. A nivell de transport, es presenta un model de desplegament compatible amb l’arquitectura general de xarxes autonomes ETSI per permetre superposicions de serveis descentralitzats. A la capa de xarxa, presentem un nou model de ”transition learning” que facilita una itinerància fluida de l’equip d’usuari a través dels l ́ımits de la xarxa. Per acabar, la part teórica és combina per revelar un model de capes superposades descentralitzades, on l’equip de l’usuari funciona de manera similar una radio FM. Un canal de radio amb accés descentralitzat.

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Shah, Kevan Dinesh. "Modulating cellular fate with arrayed cellular microenvironment technology." Diss., [La Jolla] : University of California, San Diego, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p1464669.

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Thesis (M.S.)--University of California, San Diego, 2009.
Title from first page of PDF file (viewed July 7, 2009). Available via ProQuest Digital Dissertations. Includes bibliographical references (p. 57-60).

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Joest, Mathieu von. "Dissecting the non-cell autonomous impact of cellular senescence on cellular reprogramming." Electronic Thesis or Diss., Sorbonne université, 2019. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2019SORUS396.pdf.

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La sénescence est une réponse suite à un stress qui entraîne l’arrêt permanent du cycle cellulaire. La sénescence s’accompagne de changements, notamment la sécrétion de facteurs réunis sous le terme de SASP (Senescence Associated Secretory Phenotype). Des études ont montré le rôle des cellules sénescentes et du SASP dans la régénération tissulaire. Cependant les mécanismes qui permettent d’influer sur la plasticité cellulaire dans ce contexte sont inconnus. La découverte de la reprogrammation cellulaire qui permet de reprogrammer une cellule différenciée en cellule souche pluripotente induite a mis en évidence la plasticité des cellules différenciées. Utilisant ce système comme une plateforme, nous avons montré que la sénescence induite après blessure permettait la reprogrammation du muscle via l’IL-6, qui est un tissu normalement réfractaire à la reprogrammation. Puis, j’ai montré in vitro que le SASP pouvait augmenter l’efficacité de reprogrammation cellulaire indépendamment de l’IL-6. Enfin, j’ai réalisé une étude protéomique afin d’identifier de nouveaux facteurs du SASP pouvant affecter la reprogrammation. J’ai identifié l’amphiréguline et démontré que son ajout augmente la reprogrammation cellulaire in vitro et in vivo. Ces travaux permettent de mieux comprendre comment la sénescence influe sur la plasticité cellulaire et de lier un nouveau facteur à la reprogrammation
Cellular senescence is a physiological response to a stress, leading to an irreversible cell cycle arrest. Entry in senescence goes along with a myriad of changes, one of the major being the secretion of various factors gathered under the term Senescence Associated Secretory Phenotype (SASP). Recent studies showed the role of senescent cells in regeneration, in particular through SASP. However, mechanisms enabling senescent cells to influence cellular plasticity in the context of tissue repair remain unknown. The discovery of cellular reprogramming, which allows the transformation of a differentiated cell into an induced pluripotent stem cell (iPSC), highlighted the plasticity of differentiated cells. This major breakthrough generated substantial hopes for regenerative medicine and understanding of diseases. I contributed to decipher the mechanisms by which senescence induces cellular plasticity. As a first step, we showed that injury-induced senescence could lead to the reprogramming of skeletal muscle, in particular by IL-6 secretion. Secondly, I decrypted more precisely how SASP influence the reprogramming in vitro and showed that this process could be IL-6 independent. Finally, I performed a proteomic study to identify factors secreted by senescent cells and to determine new factors that could affect reprogramming. I detected amphiregulin and showed that adding this protein enhanced the SASP effect on reprogramming. Indeed, Amphiregulin promotes reprogramming both in vitro and in vivo. Overall, this study not only allows us to better appreciate how senescence influences cellular plasticity after muscular injury, but also links up a new factor to cellular reprogramming

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Shangguan, D. K. "Cellular growth." Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.330294.

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Petrova, Siyana. "Cellular Landscapes." Thesis, KTH, Arkitektur, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-229656.

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Global climate change has been a point of concern over the past century. Some of its major consequences, which are already present, include melting of glaciers, increasing sea water level, temperature rise and excessive acidity of sea water. The natural fluctuations harm the ecology and the biological species will face increased extinction risk. The raise of the water level will cause sinking and gradually vanishing of the land’s surface as a natural resource and place for habitation. It has been estimated that if Greenland ice sheet melts completely, the water would be enough to cover the land with up to 6 meters. The project investigates the consequences of the rising sea levels due to the climate change and what impact this will have on the topography and the natural landscape. It proposes a utopian vision for a large scale strategy for agriculture which does not rely on the use of land. The structure comprises of inflatable spherical modules, which float on the water surface. It is a dynamic and expandable system, with minimal environmental footprint, designed for low-lying areas vulnerable to flooding and land shortage. The more the land surface is vanishing due to the increasing sea levels, the more the structure will stretch to compensate for the loss of farmland.

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Al, Kindi Adil Hashim 1976. "Cellular cardiomyoplasty : optimizing cellular dosage and retention by microencapsulation." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=111585.

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Cellular Cardiomyoplasty (cell therapy for myocardial regeneration) targets the basic pathophysiology of heart failure and represents a novel technique for augmenting the function of the failing heart. Previous studies have demonstrated massive mechanical losses in the first few minutes. Thus, efforts to reduce mechanical losses may prove more beneficial than those directed against biological losses alone. We believe that "Wash-out" into the disrupted blood vessels is responsible for these early losses.
In the first part of this study we hypothesized that by increasing the size of the injectate, the amount of immediate losses can be reduced achieving better retention. Using Alginate-poly-L-lysine-Alginate (APA) miscrocapsules of two different sizes (200mum&400mum) and comparing retention with bare microspheres (10mum) of similar size to MSCs, we demonstrated that immediate retention rate increased by four folds. The retention rate for group 1 (microspheres only) was 4.28+/-3.46% which was significantly lower than that for groups 2 (microspheres in 200mum microcapsules) at 16.45+/-12.66% and group 3 (microspheres in 400mum microcapsules) at 12.93+/-6.28% for Group (p<0.05). There was no difference between group 2 and 3.
In the second part, we investigated the potential of gradually increasing the cell load on functional improvement and engraftment using conventional intramuscular delivery. Five groups of rats received escalating doses of MSCs after surgically induced ischemia (gp1 no cells, gp2 0.5x 10 6, gp3 1.5x106, gp4 3x106,gp5 5x106 MSCs). At 7 weeks, we observed significant improvement in cardiac function in groups 3 to 5 compared to post-infarction baseline. This was not observed in groups 1 & 2. However, in groups 3 to 5, we observed no functional advantage for increasing the cell load beyond a minimal therapeutic dose. This is consistent with our hypothesis that small cells are washed out into the circulation.
We also showed the ability of Alginate-Poly-l-lysine-Alginate (APA) microcapsules to sustain the viability of encapsulated MSCs in-vitro. Finally, the ability of encapsulated MSCs to improve the function of the heart in-vivo was tested.

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Hosu, Basarab Gabriel. "Quantitative biological studies at cellular and sub-cellular level." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/4689.

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Thesis (Ph. D.)--University of Missouri-Columbia, 2007.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed Mar. 23, 2009). Vita. Includes bibliographical references.

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Childs, Peter Geoffrey. "Cellular mechanotransduction : development of a nanovibrational bioreactor for cellular stimulation." Thesis, University of the West of Scotland, 2016. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.739388.

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Rydholm, Susanna. "Asymmetric Cellular Miroenvironments." Licentiate thesis, KTH, Applied Physics, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4783.

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This thesis presents methods to combine 3D cell culture, microfluidics and gradients on a controlled cellular scale. 3D cultures in biological extracellular matrix gels or synthetic gels bridge the gap between organ-tissue cultures and traditional 2D cultures. A device for embedding, anchoring and culturing cells in a controlled 3D flow through micro-environment was designed and evaluated. The device was realized using an etched silicon pillar flow chamber filled with gel mixed with cells. The pillars anchor and stabilize the gel as well as increase the surface to volume ratio, permitting higher surface flow rates and improving diffusion properties. Within the structure cells were still viable and proliferating after six days of cultivation, showing that it is possible to perform medium- to-long term cultivation of cells in a controlled 3D environment.

This concept was further developed to include controllable and time stable 3D microgradient environments. In this system stable diffusion gradients can be generated by the application of two parallel fluid flows with different composition against opposite sides of a gel plug with embedded cells. Culture for up to two weeks was performed showing cells still viable and proliferating. The cell tracer dye calcein was used to verify gradient formation as the fluorescent intensity in exposed cells was proportional to the position in the chamber. Cellular response to an applied stimulus was demonstrated by use of an adenosine triphosphate gradient where the onset of an intracellular calcium release also depends on cell position.

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Knight, Thomas F., and Gerald Jay Sussman. "Cellular Gate Technology." First International Conference on UNCONVENTIONAL MODELS OF COMPUTATION, Auckland, New Zealand, 1998. http://hdl.handle.net/1721.1/29793.

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We propose a biochemically plausible mechanism for constructing digital logic signals and gates of significant complexity within living cells. These mechanisms rely largely on co-opting existing biochemical machinery and binding proteins found naturally within the cell, replacing difficult protein engineering problems with more straightforward engineering of novel combinations of gene control sequences and gene coding regions. The resulting logic technology, although slow, allows us to engineer the chemical behavior of cells for use as sensors and effectors. One promising use of such technology is the control of fabrication processes at the molecular scale.
DARPA/ONR Ultrascale Computing Program under contract N00014-96-1-1228 and by the DARPA Embedded Computing Program under contract DABT63-95-C130.

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Rydholm, Susanna. "Asymmetric Cellular Microenvironments." Licentiate thesis, Stockholm : Tillämpad fysik, Applied Physics, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4783.

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Collins, Sean. "Interactive cellular automata." Thesis, Lancaster University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435877.

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Zhou, Felix. "Phenotyping cellular motion." Thesis, University of Oxford, 2017. http://ora.ox.ac.uk/objects/uuid:9fb6a57d-2e16-43c9-92e6-895330353e51.

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In the development of multicellular organisms, tissue development and homeostasis require coordinated cellular motion. For example, in conditions such as wound healing, immune and epithelial cells need to proliferate and migrate. Deregulation of key signalling pathways in pathological conditions causes alterations in cellular motion properties that are critical for disease development and progression, in cancer it leads to invasion and metastasis. Consequently there is strong interest in identifying factors, including drugs that affect the motion and interactions of cells in disease using experimental models suitable for high-content screening. There are two main modes of cell migration; individual and collective migration. Currently analysis tools for robust, sensitive and comprehensive motion characterisation in varying experimental conditions for large extended timelapse acquisitions that jointly considers both modes are limited. We have developed a systematic motion analysis framework, Motion Sensing Superpixels (MOSES) to quantitatively capture cellular motion in timelapse microscopy videos suitable for high-content screening. MOSES builds upon established computer vision approaches to deliver a minimal parameter, robust algorithm that can i) extract reliable phenomena-relevant motion metrics, ii) discover spatiotemporal salient motion patterns and iii) facilitate unbiased analysis with little prior knowledge through unique motion 'signatures'. The framework was validated by application to numerous datasets including YouTube videos, zebrafish immunosurveillance and Drosophila embryo development. We demonstrate two extended applications; the analysis of interactions between two epithelial populations in 2D culture using cell lines of the squamous and columnar epithelia from human normal esophagus, Barrett's esophagus and esophageal adenocarcinoma and the automatic monitoring of 3D organoid culture growth captured through label-free phase contrast microscopy. MOSES found unique boundary formation between squamous and columnar cells and could measure subtle changes in boundary formation due to external stimuli. MOSES automatically segments the motion and shape of multiple organoids even if present in the same field of view. Automated analysis of intestinal organoid branching following treatment agrees with independent RNA-seq results.

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Duclos, Guillaume. "Active Cellular Nematics." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066498.

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Des cellules allongées et apolaires cultivées à confluence s'alignent les unes avec les autres. Dans cette thèse, nous utilisons des concepts de la théorie de la matière active ainsi que de la physique des cristaux liquides afin d'étudier quantitativement l'émergence de cet ordre mésoscopique nématique pour des monocouches de cellules à deux dimension, avec et sans confinement. Il a été montré que les défauts topologiques jouent un rôle crucial durant l'auto-organisation de systèmes biologiques actifs. Ici, nous étudions la dynamique de ces défauts qui se forment dans le tissu nématique contractile. Étant intrinsèquement hors équilibre à cause de la consommation d'énergie par les cellules, la monocouche est parcourue par de complexes courants de cellules due à la migration spontanée des défauts et leur annihilation avec des défauts de charges opposées. En comparant nos résultats expérimentaux avec un modèle théorique, nous montrons que l'auto-organisation de la monocouche est liée à la minimisation de l'énergie de courbure du tissu
Elongated, weakly interacting, apolar cells cultured at confluence align together, forming large domains where they are perfectly ordered. Using concepts from the active matter theory and the physics of liquid crystals, we study the emergence of this mesoscopic nematic order by quantifying the ordering dynamics in two-dimensional infinite monolayers or under confinement. Topological defects have been found to play a crucial role in the self-organization of active biological systems. We study the dynamics of the disclinations that form in these cellular contractile nematics. Being driven out of equilibrium by the consumption of energy by individual cells, the monolayer exhibits complex flow patterns as defects migrate spontaneously and annihilate pairwise. By comparing our experimental results to a nematic drop model, we show that the self-organization of the cellular nematic layer with no boundary conditions or under circular confinement is dictated by the minimization of the splay and bend distortions of the tissue

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Sélo-Carreau, Aude. "Rôle du monoxyde d'azote dans la reconnaissance cellulaire : étude d'un modèle endothélial lié au mélanome." Thesis, Orléans, 2010. http://www.theses.fr/2010ORLE2028/document.

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Le mélanome est le cancer de la peau le plus rare, mais celui qui cause le plus de mortalité. L’étapecritique de sa progression est l’angiogenèse, processus détourné par la tumeur pour s’oxygéner et senourrir. Les cellules tumorales peuvent alors former des métastases dans les ganglions lymphatiques,notamment. D’autre part, la tumeur inhibe les réponses immunitaires de l’hôte à son encontre. Tousces mécanismes font intervenir le monoxyde d’azote (NO ). Le but de ce projet a été d’approfondir lerôle du NO dans l’angiogenèse et le recrutement leucocytaire, mécanismes basés sur lareconnaissance cellulaire de l’endothélium.Nous avons montré que le NO est nécessaire à l’angiogenèse, mais que des doses plus fortes sontanti-angiogéniques. Cet effet inhibiteur peut s’expliquer par la diminution des interactions cellules-cellules,et l’inhibition de l’expression de PECAM-1/CD31, principalement.D’autre part, nous avons établi que l’adhésion des leucocytes est inhibée par le NO ce qui a été reliéà la modulation de l’expression des molécules capables de fixer des chimiokines : lesglycosaminoglycannes et les récepteurs de chimiokines, ainsi qu’à la sous-expression des moléculesd’adhésion CD34, ICAM-2/CD102 et VCAM-1/CD106.En conclusion, le NO est capable de réguler des mécanismes cellulaires majeurs de la progressiontumorale, par modulation de l’expression des molécules de surface de l’endothélium. Tout au long dece travail, nous avons observé que les différences de réponse sont dépendantes des doses de NO etdu type cellulaire, ce qui démontre le rôle pivot du NO dans la progression du cancer
Melanoma is the rarest skin cancer, but one that causes the most of deaths. The critical step of itsprogression is angiogenesis, a physiological tumor-activated process which allows the delivery ofoxygen and nutrients. Tumor cells may then metastasize to the lymph nodes, in particular. Moreover,the tumor inhibits the host immune responses toward itself. All these mechanisms are regulated bynitric oxide (NO ). The aim of the project was to deepen the role of NO in angiogenesis andleukocyte recruitment, two mechanisms based on endothelial cell recognition.We have shown here that NO is necessary for angiogenesis, but that high concentrations are antiangiogenic.This inhibitory effect of NO can be attributed to the decrease of cell-cell interactions andthe inhibition of the PECAM-1/CD31 expression, mainly.Besides, we have demonstrated that leukocyte adhesion on endothelium is inhibited by NO . This canbe explained by the modulation of the expression of molecules able to bind to chemokines:glycosaminoglycans and chemokine receptors, as well as by the down-regulation of the adhesionmolecules CD34 and ICAM-2/CD102 VCAM-1/CD106.In conclusion, NO is able to regulate the main cellular mechanisms of tumor progression bymodulating the expression of surface molecules on endothelial cells. Throughout this work, we haveobserved that these modulations depend on NO concentrations and on the cell type, demonstratingthe pivotal role of NO in cancer progression

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Gao, Ziyang. "Dynamic behavior of cellular materials and cellular structures : experiments and modeling /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?MECH%202005%20GAOZ.

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Ruiz, Maxime. "Le TGFβI dans la physiopathologie de l'arthrose et son rôle dans l'effet thérapeutique des cellules souches mésenchymateuses." Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTT008/document.

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L’arthrose est une maladie ostéoarticulaire fréquente et sans traitement curatif. Elle se manifeste par une dégénérescence du cartilage, associée à une altération des autres tissus de l’articulation. Dans ce contexte, les cellules souches mésenchymateuses (CSM) démontrent un effet thérapeutique. Afin d’identifier de nouveaux médiateurs de l’homéostasie articulaire, nous avons analysé le secrétome des CSM en nous focalisant sur les membres de la famille du facteur de croissance transformant β (TGFβ), une voie centrale dérégulée dans l’arthrose.Cette approche nous a permis d’identifier la protéine induite par le TGFβ (TGFβI ou βIGH3), pour laquelle nous avons évalué le rôle dans la différenciation des CSM et comparé l’expression dans les tissus articulaires de patients arthrosiques et de sujets sains.Nous montrons l’importance du TGFβI dans la régulation des processus de différenciation osseuse et chondrogénique des CSM. Nous mettons également en évidence une dérégulation au niveau transcriptionnel et protéique de ce facteur dans le cartilage, l’os sous-chondral ainsi que les CSM de patients arthrosiques. En testant son implication dans l’effet thérapeutique des CSM sur des modèles d’arthrose in vitro et in vivo, nous montrons que la diminution de son expression dans les CSM annule leur effet thérapeutique dans les modèles d’arthrose. Cet effet chondroprotecteur du TGFβI est associé à une inhibition du remodelage osseux et de la calcification des tissus mous articulaires.L’ensemble de nos résultats démontrent l’importance de la régulation de la voie TGFβ, et plus particulièrement du TGFβI, dans l’homéostasie articulaire. En parallèle, nos travaux illustrent le rôle de ce facteur dans l’effet thérapeutique des CSM, et suggèrent que l’altération de son expression dans les CSM de patients arthrosiques soit à l’origine d’une diminution de leur potentiel régénératif
Osteoarthritis (OA) is the most common form of joint diseases without curative treatments. The disease is mainly characterized by the degradation of articular cartilage which is associated with other pathological changes in joint tissues. In this context, mesenchymal stem cells (MSC) have demonstrated a therapeutic effect. In order to identify new mediators involved in articular homeostasis, we analyzed MSC secretome, focusing on the transforming growth factor β (TGFβ) members, a central pathway dysregulated in OA.This approach allows us to identify the TGFβ induced protein (TGFβI or βIGH3). In the present study, we evaluated its role in the differentiation of MSC and compared its expression in articular tissues from OA patients and healthy donors.We highlight the importance of TGFβI in the regulation of differentiation of MSC towards bone and cartilage. We also demonstrate its dysregulation at both transcript and protein level in cartilage, bone and MSC from OA patients. We then evaluated its role in the therapeutic effect of MSC in vitro and in vivo and demonstrated that its decreased expression in MSC is associated with a loss of their therapeutic effect in OA models. The chondroprotective effect of TGFβI is associated with an inhibition of bone remodeling and calcification of soft articular tissues.Together, our results highlight the importance of the TGFβ pathway, and specially of TGFβI regulation, in joint homeostasis. Moreover, our work demonstrates its role in the therapeutic effect of MSC, suggesting that its dysregulation in OA MSC could lead to a decreased regenerative potential

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Weston, James. "Cellular Automata Based Binary Arithmetic Implemented Within A Fault Tolerant Cellular Architecture." Thesis, University of Kent, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.499644.

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Liu, Kuo-Kang. "Deformation of cellular entities." Thesis, Imperial College London, 1995. http://hdl.handle.net/10044/1/8167.

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Wang, Chunfang. "Cellular senescence in mice." Thesis, University of Newcastle upon Tyne, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485568.

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Mugume, Edwin. "Green heterogeneous cellular networks." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/green-heterogeneous-cellular-networks(e7976a91-c891-4174-abaf-18820ff1736d).html.

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Data traffic demand has been increasing exponentially and this trend will continue over theforeseeable future. This has forced operators to upgrade and densify their mobile networks toenhance their capacity. Future networks will be characterized by a dense deployment of different kinds of base stations (BSs) in a hierarchical cellular structure. However network densification requires extensive capital and operational investment which limits operator revenues and raises ecological concerns over greenhouse gas emissions. Although networks are planned to support peak traffic, traffic demand is actually highly variable in both space and time which makes it necessary to adapt network energy consumption to inevitable variations in traffic demand. In this thesis, stochastic geometry tools are used to perform simple and tractable analysis of thecoverage, rate and energy performance of homogeneous networks and heterogeneous networks(HetNets). BSs in each tier are located according to independent Poisson Point Processes(PPPs) to generate irregular topologies that fairly resemble practical deployment topologies. The homogeneous network is optimized to determine the optimal BS density and transmit power configuration that minimizes its area power consumption (APC) subject to both coverage and average rate constraints. Results show that optimal transmit power only depends on the BSpower consumption parameters and can be predetermined. Furthermore, various sleep modemechanisms are applied to the homogeneous network to adapt its APC to changes in userdensity. A centralized strategic scheme which prioritize BSs with the least number of usersenhances energy efficiency (EE) of the network. Due to the complexity of such a centralizedscheme, a distributed scheme which implements the strategic algorithm within clusters of BSsis proposed and its performance closely matches that of its centralized counterpart. It is more challenging to model the optimal deployment configuration per tier in a multi-tier HetNet. Appropriate assumptions are used to determine tight approximations of these deployment configurations that minimize the APC of biased and unbiased HetNets subject tocoverage and rate constraints. The optimization is performed for three different user associationschemes. Similar to the homogeneous network, optimal transmit power per tier also depends onBS power consumption parameters only and can also be predetermined. Analysis of the effect of biasing on HetNet performance shows appropriate biasing can further reduce the deploymentconfiguration (and consequently the APC) compared to an unbiased HetNet. In addition, biasing can be used to offload traffic from congesting and high-power macro BSs to low-power small BSs. If idle BSs are put into sleep mode, more energy is saved and HetNet EE improves. Moreover, appropriate biasing also enhances the EE of the HetNet.

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Rebocho, Ana Paula da Mota Torres. "Cellular signalling by Araf." Thesis, University of London, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.531334.

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MacNair, David Luke. "Modeling cellular actuator arrays." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50259.

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This work explores the representations and mathematical modeling of biologically-inspired robotic muscles called Cellular Actuator Arrays. These actuator arrays are made of many small interconnected actuation units which work together to provide force, displacement, robustness and other properties beyond the original actuator's capability. The arrays can also exhibit properties generally associated with biological muscle and can thus provide test bed for research into the interrelated nature of the nervous system and muscles, kinematics/dynamics experiments to understand balance and synergies, and building full-strength, safe muscles for prosthesis, rehabilitation, human force amplification, and humanoid robotics. This thesis focuses on the mathematical tools needed bridge the gap between the conceptual idea of the cellular actuator array and the engineering design processes needed to build physical robotic muscles. The work explores the representation and notation needed to express complex actuator array typologies, the mathematical modeling needed to represent the complex dynamics of the arrays, and properties to guide the selection of arrays for engineering purposes. The approach is designed to aid automation and simulation of actuator arrays and provide an intuitive base for future controls and physiology work. The work is validated through numerical results using MatLab's SimMechanics dynamic modeling system and with three physical actuator arrays built using solenoids and shape memory alloy actuators.

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Willcocks, James Peter. "Magnesium in cellular energetics." Thesis, University of Oxford, 2002. http://ora.ox.ac.uk/objects/uuid:f4f5de76-8c72-4b42-8bd4-eb151485d47e.

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Most cellular magnesium is bound, yet it is the concentration of free magnesium, [Mg²⁺]_free, in red blood cells that is vital in the regulation of enzyme activity and ion transport. It is unknown how changes in total blood magnesium affect the [Mg²⁺]_free within red blood cells or in tissue, because the presence of other cations, especially H⁺ and potassium, K⁺ , affects the degree to which Mg²⁺ is bound. Consequently, this Thesis presents a new ³¹P NMR spectroscopic method to measure [Mg²⁺]_free in blood, which analyses the changes in the phosphorus chemical shifts of ATP and 2,3-DPG using theoretical equations expressing the observed chemical shift as a function of pH, K⁺ and [Mg²⁺]_free, over the pH range of 5.75 to 8.5 and [Mg²⁺]_free range 0 to 5 mM. The equations were adjusted for the binding of haemoglobin to ATP and DPG, which required knowledge of the intracellular concentrations of ATP, DPG, K⁺ and Hb. These equations enabled, for the first time, the simultaneous analyses of the chemical shifts of 3P-DPG and β-ATP to measure both intracellular 04- pH and [Mg²⁺]_free in normal and sickle blood. To simulate in vivo 100% oxygenated blood, samples were prepared for analysis by equilibration with a mixture of O₂ and CO₂, adjusted to give a pCO₂ of 40 mmHg and pO₂ > 150 mmHg. Under these conditions, normal whole blood had an intracellular pH of 7.20 ± 0.02 and a [Mg²⁺]_free of 0.41 ± 0.03 mM (n = 33). Further work determined blood pH and [Mg²⁺]_free for several clinical conditions including sickle cell anaemia, pre-eclampsia, hypoxia, patients with sub-arachnoid haemorrhage and chronic fatigue syndrome. This Thesis has demonstrated the potential of this new technique to evaluate the importance of [Mg²⁺]_free in the regulation of metabolite concentration and metabolic function, and to elucidate some of the properties of magnesium transport across the erythrocyte cell membrane.

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Glover, Beverley Jane. "Cellular differentiation in plants." Thesis, University of East Anglia, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338247.

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Torbett, Neil Edward. "Cellular roles of PKN1." Thesis, University College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406323.

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Hughes, Phillipa Jane. "Cellular responses to aluminium." Thesis, University of Liverpool, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262389.

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Hazlerigg, David G. "Cellular actions of melatonin." Thesis, University of Cambridge, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295370.

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Carney, Matthew Eli. "Discrete cellular lattice assembly." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/101845.

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Thesis: S.M., Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 109-113).
Robotic assembly of discrete cellular lattices at super-hertz (>1Hz) assembly rates is shown to be possible by integrating the design of a modular robotic assembler with the specified lattice topology such that the lattice can itself be removed from the incremental assembly process. Limits to assembly rates are ultimately dependent on allowable error, system stiffness, and damping characteristics. Vibrations due to cyclical motions of the end-effector, locomotion system, and the dynamic response of an incrementally varying lattice must settle to acceptable ranges to enable engagement between end-effectors, discrete elements, and their affixing features to adjacent cells. For given system dynamics, longer settling times enables greater energy dissipation, and less error. With a greater allowable error at the interface, a shorter assembly cycle period can be attained. Passive alignment features designed into the robot end-effectors, locomotion systems, and the discrete lattice elements reduce the precision requirements of the assembly process by opening up the acceptable error range, thereby, enabling higher assembly cycle-rates. An experiment was performed to evaluate how an assembler locally referencing a lattice performed in comparison to a globally referenced assembler. The two assemblers were of similar kinematic form: both gantry-type CNC machines: a ShopBot and a custom built relative robotic assembler. The results showed superior performance by the global coordinate frame system. An error budget analysis of the two systems showed that the locally referenced, lattice based system had a larger more variable structural loop than the global coordinate frame ShopBot. The control experiment, demonstrated 0.1Hz assembly rates, while first order approximations predict a maximum 4Hz cycle for the specified interface geometry. Results show that in order to successfully assemble discrete cellular lattices at super-hertz rates the robot must itself become the local, instantaneous global coordinate frame such that the structural loop is absolutely minimized, while stiffness is maximized; at the instantaneous moment of assembly the structural loop of the robot must reference only itself.
by Matthew Eli Carney.
S.M.

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Wang, Ying. "Dynamic Cellular Cognitive System." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/29146.

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Dynamic Cellular Cognitive System (DCCS) serves as a cognitive network for white space devices in TV white space. It is also designed to provide quality communications for first responders in area with damaged wireless communication infrastructure. In DCCS network, diverse types of communication devices interoperate, communicate, and cooperate with high spectrum efficiency in a Dynamic Spectrum Access (DSA) scenario. DCCS can expand to a broad geographical distribution via linking to existing infrastructure. DCCS can quickly form a network to accommodate a diverse set of devices in natural disaster areas. It can also recover the infrastructure in a blind spot, for example, a subway or mountain area. Its portability and low cost make it feasible for commercial applications. This dissertation starts with an overview of DCCS network. DCCS defines a cognitive radio network and a set of protocols that each cognitive radio node inside the network must adopt to function as a user within the group. Multiple secondary users cooperate based on a fair and efficient scheme without losing the flexibility and self adaptation features. The basic unit of DCCS is a cell. A set of protocols and algorithms are defined to meet the communication requirement for intra-cell communications. DCCS includes multiple layers and multiple protocols. This dissertation gives a comprehensive description and analysis of building a DCCS network. It covers the network architecture, physical and Medium Access Control (MAC) layers for data and command transmission, spectrum management in DSA scenario, signal classification and synchronization and describes a working prototype of DCCS. 3 Two key technologies of intra-cell communication are spectrum management and Universal Classification and Synchronization (UCS). A channel allocation algorithm based on calculating the throughput of an available is designed and the performance is analyzed. UCS is conceived as a self-contained system which can detect, classify, and synchronize with a received signal and extract all parameters needed for physical layer demodulation. It enables the accommodation of non-cognitive devices and improves communication quality by allowing a cognitive receiver to track physical layer changes at the transmitter. Inter-cell communications are the backhaul connections of DCCS. This dissertation discusses two approaches to obtaining spectrum for inter-cell communications. A temporary leasing approach focuses on the policy aspects, and the other approach is based on using OFDMA to combine separate narrowband channels into a wideband channel that can meet the inter-cell communications throughput requirements. A prototype of DCCS implemented on GNU radio and USRP platform is included in the dissertation. It serves as the proof of concept of DCCS.
Ph. D.

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Edwards, Richard J. "Cellular interactions with hydrogels." Thesis, Aston University, 2001. http://publications.aston.ac.uk/9653/.

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An efficient means of evaluating potential biomaterials is to use the in vitro fibroblast cell culture model. However, the chemistry which influences cell adhesion on polymer substrates is poorly understood. The work in this thesis aims to rationalise several theories of current opinion and introduce new chemical techniques that may predict cellular behaviour. The keratoprosthesis is a typical example of the need to be able to manipulate cell adhesion of materials since both adhesive and non adhesive sections are needed for proper integration and optical function. Calcein AM/ethidium homodimer-1 and DAPI assays were carried out using 3T3 and EKl.BR cells. Poly(HEMA) was found to be the most cell adhesive hydrogel tested. The reactivity of monomers and the resulting sequence distribution were found to affect surface properties and this may explain the poor levels of cell adhesion seen on NVP/MMA copolymers. Surface free energy is shown to be dependent on the polar and non polar groups present along the backbone chain of the polymers. Dehydrated and hydrated contact angle measurements show the effect of rotation of surface groups around the backbone chain. This effect is most apparent on hydrogels containing methacrylic acid. Dynamic contact angle measurements confirm sequence distribution irregularities and demonstrate the mobility of surface groups. Incorporation of NVI or DEAEMA into the hydrogels does not affect the mobility of the surface groups despite their bulkiness. Foetal calf serum was used for the first time as a test solution in an attempt to mimic a biological environment during surface experiments. A Vroman effect may be present, and may involve different surface proteins for each material tested. This interdisciplinary study combines surface characterisation and biological testing to further the knowledge of the biomaterial/host interface. Surface chemistry techniques appear to be insufficiently sensitive to predict cellular behaviour. The degree of ionisation of hydrogels containing ionic groups depends on the nature of the functional groups as well as the concentration and this is an important parameter to consider when comparing charged materials.

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Gray, Peter. "Phase-locked cellular oscillators." Thesis, University of Aberdeen, 1996. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU089854.

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Biological oscillators occur frequently in nature---and many systems, such as the growth of certain bacteria, are governed by the 24-hour circadian clock. Furthermore biological phase-locked oscillators, as identified by researchers, are clearly an integral part of the structure of the brain in humans, and in animals in general. Such systems are most conveniently investigated via computer models. This thesis describes the computer-modelling of phase-locked systems in which the oscillator is a cellular automaton---a device often used by scientists to model the growth or decay of populations within biological and other systems. The latter part of the thesis shows how these computer models have been implemented in a two-dimensional form using gate array technology, and results are presented to demonstrate the overall loop performance. It is not suggested that the phase-locked loops described in this thesis should be translated directly into practical commercial products---the primary objective of the research described being to originate a new type of phase-locked loop based around a novel variable frequency oscillator. However, the summary at the end of the thesis indicates how the designs might be modified so as to allow a direct silicon implementation.

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Valtchev, Peter Dimitrov. "Contact dependent cellular interactions." Thesis, The University of Sydney, 2013. http://hdl.handle.net/2123/12021.

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The aim of this study was to investigate the contact dependent cellular interactions of neoplastic cells and somatic cells in vitro. These interactions were examined as homotypic and heterotypic interactions with focus on plasma membrane exchange and complete cell fusion of two cells. Plasma membrane exchange between the cancer cells and between cancer cells and primary fibroblasts was characterized in absolute and kinetic terms. It was found that primary human fibroblasts from skin and gingival origin were superior to cancer cells in terms of membrane exchange. This important finding demonstrates that membrane exchange similar to trogocytosis is not only a feature of immune and cancer cells as previously thought but has an important significance as cell-cell communication mechanism involved in tissue homeostasis. Complete cell fusion was examined by tagging the cell nucleus with a non-replicating baculovirus expressing chimeric nuclear proteins tagged with green and red fluorescent proteins. Complete cell fusion was not observed with fibroblasts and was only detected with SAOS-2 and MCF-7 cancer cells. It was shown that this resulted in complete nuclear fusion as the double positive cells were syncarions without exception. A large scale comparative profiling of the plasma membrane proteome of the two osteosarcoma cell lines: the good fuser SAOS-2 and the inferior one MG-63 was undertaken. Several proteins with possible involvement in the cell fusion process were identified. GP73 a protein strongly expressed in hepatocytes-derived syncytial giant cells and SED1/MFG-E8, a glycoprotein with role in sperm-egg fusion were found on the surface of SAOS-2 cells. Additionally, the presence of heat-shock proteins HSP-90 and HSP-70 which are molecular chaperons and interact with wide range of proteins were also detected on both SAOS-2 and MG-63 and thus identified as new bio-markers of osteosarcoma.

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NG, Ho Yin. "Cellular Characteristics of Lymphangioleiomyomatosis." Thesis, The University of Sydney, 2013. http://hdl.handle.net/2123/9510.

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Lymphangioleiomyomatosis (LAM) is a rare lung disease in young women. Dysfunction of the tuberous sclerosis gene complex (TSC)-1 and TSC2 contributes to the manifestations of enhanced proliferation and migration of smooth muscle-like cells (LAM cells), elevated matrix metalloproteinase (MMP) activity and increased lymphangiogenesis. Currently there is no effective treatment for this fatal disease. This study aimed to assess the effectiveness of potential pharmacotherapies (doxycycline, statins and lamstatin) in targeting the different pathological aspects of LAM. Studies in this thesis examined the effects of doxycycline in human LAM cells and in a cellular model for LAM. Doxycycline had no effect on cell proliferation, but reduced elevated MMP2 activity, migratory capability and wound closure. In addition, doxycycline reduced cell migration through the inhibition of RhoA-GTPase and focal adhesion kinase (FAK), proteins that are involved in the regulation of cell motility. These findings were extended to show that the combination of doxycycline and rapamycin (inhibitor of the mammalian target of rapamycin compelx 1 [mTORC1] which is a potent inhibitor of cell proliferation) exhibited an additive effect on the inhibition of wound closure compared to the individual drugs alone. MMP profiles in people with LAM were also examined and confirmed previous findings of elevated serum MMP2 and MMP9. In addition elevated serum levels of MMP1 and MMP3 were identified. The effectiveness of statins as a treatment for LAM was examined in studies which investigated their effects on the enhanced proliferation, migration, wound closure and MMP2 activity in TSC2-deficient cells. All parameters were reduced by simvastatin and fluvastatin. The anti-lymphangiogenic protein lamstatin (NC1 domain of collagen IV α5) is absent in the lungs of people with LAM. Results showed that lamstatin and its consensus peptide, CP17 inhibited the proliferation, migration and wound closure in a cellular model of LAM. These studies have enhanced our understanding of the disease mechanisms underlying LAM and have revealed potential molecular targets for future therapy in this disease.

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SUN, YONGTAO. "Multifunctional Hierarchical Cellular Solids." Doctoral thesis, Politecnico di Torino, 2013. http://hdl.handle.net/11583/2507349.

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Due to their peculiar low density properties, cellular solids are widely used in industries and play a very important role in our daily life. Two of the most studied celluar solids are honeycombs and foams. With the development of nanotechnology, another kind of cellular solids - carbon based materials are drawing more and more attentions nowadays, e.g., the carbon nanotube related researches. The other very hot research field is the bio-inspired materials. Many efforts have been made by the scientists all over the world and a lot of insightful results are obtained. No matter the well studied celluar solids or the newly studied natural and artificial materials, what we care about them are not only their mechicanl properties but also the multifunctionality they may display, in order that they could serve the human being more effectively and more conveniently. Therefore, in this thesis we have focused on the multifunctional hierarchical cellular solids. In the first chapter, by reviewing some recent developments of the cellular solids, honeycombs and carbon nanotube networks, we summarized the potential multifunctionality they show and thus the significance they may be of for practical applications. Based on this simple review, the motivation of this thesis is introduced, which is to explore the multifunctionalities of these two kinds of cellular solids more widely and deeply. In chapter 2, through the effective media model, the thermal and thermomechanical performances of the two-dimensional metal honeycombs (with relative density less than 0.3), hexagonal, triangular, square and Kagome honeycombs, are systematically studied. To improve the in-plane stiffness of the regular hexagonal honeycombs, in chapters 3 and 4 we proposed the multifunctional hierarchical honeycombs (MHH). The MHH is constructed by substituting the cell wall of an original regular honeycomb with five different equal mass lattices, hexagonal, triangular, Kagome, re-entrant hexagonal and chiral honeycombs, respectivley. Elastic and transport properties of the MHH with hexagonal, triangular and Kagome substructures are studied. In-plane stiffnesses of the MHH with re-entrant hexagonal and chiral honeycombs are analyzed. Chapter 5 involves the cellular solids, super carbon nanotubes (STs). To avoid the diameter shrinkage that the normal STs under uniaxial tension show, a new kind of hierarchical fibers with a negative Poisson’s ratio for tougher composites is proposed and their equivalent elastic parameters are calculated. Chapter 6 reported an application of the hierarchical fibers in bridged crack model. Chapter 7 provides conclusions and an outlook for the future work.

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Hashimoto, Kyoichi. "Cellular context-dependent consequences of Apc mutations on gene regulation and cellular behavior." Kyoto University, 2018. http://hdl.handle.net/2433/230974.

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Haque, Khawaja Mostaq Gausul. "The quantitation of cellular allo-immunity in preparation for monitoring of cellular tolerance." Thesis, University of Bristol, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389232.

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Bake, Mohamadi Siamak. "Behaviour of cellular beams and cellular composite floors at ambient and elevated temperatures." Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/behaviour-of-cellular-beams-and-cellular-composite-floors-at-ambient-and-elevated-temperatures(18b84174-d363-452e-aa6c-eabc860d84ab).html.

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Cellular beams (CBs) have become increasingly popular in the UK and other countries over the recent years. However, the research into the behaviour of these beams has not advanced at the same rate. There is still no robust codified guidance available to design cellular beams and cellular composite beams at ambient and elevated temperatures. Meanwhile, numerical simulation approaches, such as Finite Element (FE) analysis, have enabled the researchers to advance their investigations into various behavioural aspects of these beams. In this research, the developed numerical models using the ABAQUS package were able to predict, to a high accuracy, the failure mode and failure load (temperature) of CBs and cellular composite beams at ambient and elevated temperatures.Within the investigations on cellular beams, it was found that predicting the correct failure mode by FE models can be extremely sensitive to the maximum load increment allowed in the software (for elastic-perfectly plastic stress-strain relationship for steel material) and also to the applied boundary conditions. In particular, slight changes in the boundary conditions applied to the top flange of the beam, can change the failure mode from web post buckling to Vierendeel mechanism. The buckling resistance of the web post of cellular composite beams was found to be sensitive to the amplitude of web imperfections at ambient temperature. However, the ultimate resistance of these beams was not affected by the amplitude of web imperfections at elevated temperature. This suggests that the 'Strut' model used in current design method to estimate the buckling resistance of the web post is not reasonable at elevated temperature and needs to be modified. The failure of cellular composite beams under a uniform distributed load (UDL) and at elevated temperatures, was governed by distorsional buckling before the development of web post buckling. Adding full-height web stiffeners to the beam in such cases improved their loading resistance at ambient temperature by up to 15% and prevented the occurrence of distorsional buckling at elevated temperature. Increasing the end-restraints decreased the deflections of CBs which are governed by catenary action at elevated temperature. However, this also critically promoted the occurrence of web post buckling which could be due to the P-∆ effects and instabilities resulting from the restrained expansion of the beam.Asymmetric beams showed a higher sensitivity and vulnerability to the magnitude of the load ratio than symmetric sections. This suggests a more prudent approach for the fire design of asymmetric beams as opposed to symmetric beams.

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Hennig, Katharina. "Dynamique des forces motiles et brisure de symétrie chez la cellule migrante." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAY040/document.

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La motilité cellulaire directionnelle au cours du développement de l'organisme et des tissus, l'homéostasie et la maladie nécessite une rupture de symétrie. Ce processus repose sur la capacité des cellules individuelles à établir une polarité avant-arrière, et peut se produire en l'absence de signaux externes. L'initiation de la migration a été attribuée à la polarisation spontanée des composants du cytosquelette, tandis que l'évolution spatio-temporelle des forces du cytosquelette résultant de l'interaction mécanique cellule-substrat continue n'a pas encore été résolue. Ici, nous établissons un test de migration microfabriqué unidimensionnel qui imite un environnement fibrillaire complexe in vivo tout en étant compatible avec les mesures de force à haute résolution, la microscopie quantitative et l'optogénétique. La quantification des paramètres morphométriques et mécaniques révèle un comportement de stick-slip générique initié par un détachement stochastique des contacts adhésifs d'un côté de la cellule dépendant de la contractilité, qui est suffisant pour conduire la motilité cellulaire directionnelle en absence de polarité du cytosquelette préétablie ou de gradients morphogènes. Un modèle théorique valide le rôle crucial de la dynamique d'adhésion au cours de la rupture de symétrie spontanée, en proposant que le phénomène examiné puisse émerger indépendamment d'un système auto-polarisant complexe
Directional cell motility during organism and tissue development, homeostasis and disease requires symmetry breaking. This process relies on the ability of single cells to establish a front-rear polarity, and can occur in absence of external cues. The initiation of migration has been attributed to the spontaneous polarization of cytoskeleton components, while the spatio- temporal evolution of cytoskeletal forces arising from continuous mechanical cell-substrate interaction has yet to be resolved. Here, we establish a one- dimensional microfabricated migration assay that mimics complex in vivo fibrillar environment while being compatible with high-resolution force measurements, quantitative microscopy, and optogenetics. Quantification of morphometric and mechanical parameters reveals a generic stick-slip behavior initiated by contractility-dependent stochastic detachment of adhesive contacts at one side of the cell, which is sufficient to drive directional cell motility in absence of pre-established cytoskeleton polarity or morphogen gradients. A theoretical model validates the crucial role of adhesion dynamics during spontaneous symmetry breaking, proposing that the examined phenomenon can emerge independently of a complex self-polarizing system

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Evans, Braun Tamara Zoe Marie. "The involvement of HCMV and cellular replication proteins in viral and cellular DNA replication." Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608577.

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Patwardhan, Anand. "Role of the small GTPase RAB6 in pigmentation." Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCB090.

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Clemot, Marie. "Role of CAF-1 in the establishment and maintenance of cellular identity during development in Drosophila." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066149.

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L’organisation de l’ADN sous forme de chromatine joue un rôle crucial dans la régulation de l’identité cellulaire. De par son rôle clé dans l’assemblage de la chromatine couplé à la synthèse d’ADN, le chaperon d’histone CAF-1 apparaît comme un acteur potentiel dans la transmission de l’information portée par la chromatine au cours des générations cellulaires. Bien que CAF-1 soit essentiel pour la survie au stade larvaire chez la Drosophile, les outils génétiques disponibles chez cet organisme permettent d’analyser sa fonction dans des types cellulaires ciblés. Mon travail montre que la grande sous-unité de CAF-1 (P180) est essentielle pour le maintien de la lignée germinale femelle. L’arrêt précoce de l’ovogénèse induit par la perte de P180 dans les cellules germinales a pu être attribué à l’activation de checkpoints, vraisemblablement en réponse à une accumulation d’ADN simple-brin liée à des défauts de réplication. De façon remarquable, les cellules souches germinales (GSCs) traversent une « crise identitaire » en absence de P180 : elles présentent des caractéristiques de cellules en cours de différenciation, dont une abscission incomplète, tout en conservant des propriétés spécifiques aux GSCs. En revanche, mon analyse n’a pas révélé de défaut d’identité des neuroblastes, une autre population de cellules souches, qui continuent de se diviser de façon asymétrique sans P180. De même, les cellules des disques imaginaux se divisant de façon symétrique prolifèrent en absence de P180, bien que plus lentement. Des analyses complémentaires permettront de déterminer si des mécanismes alternatifs d’assemblage de la chromatine compensent la perte de CAF-1 dans ces cellules
The organization of DNA into chromatin is dynamic and plays important roles in the establishment and the maintenance of cellular identity. By virtue of its central role in replication-coupled chromatin assembly, the histone chaperone CAF-1 constitutes an interesting candidate in a search for molecular players involved in the inheritance of chromatin states in mitotic cells. In Drosophila, dCAF-1 is essential for viability at the larval stage. Yet, the genetic tools available in the fruit fly allow to analyze the function of dCAF-1 in specific tissues. Mainly, my thesis work shows that the large subunit of dCAF-1 (P180) is essential for oogenesis. I have shown that the early arrest of oogenesis observed upon depletion of P180 in germ cells results from the activation of checkpoints pathways and cell death, possibly in response to the accumulation of single-strand DNA as a consequence of replication defects. Strikingly, P180 plays an essential role in the female germline stem cells (GSCs), which upon depletion of P180 enter an “identity crisis” and harbor features of differentiating cyst cells, including incomplete abscission, while maintaining at the same time some GSCs features. In contrast, the loss of P180 does not seem to alter the identity of larval neuroblasts, another population of stem cells, which continue to divide in an asymmetric fashion in its absence. Finally, the cells of the imaginal discs, which divide symmetrically, are able to proliferate upon loss of P180, albeit at a slower rate. Further analyses are required to determine whether alternative chromatin assembly pathways compensate for the loss of dCAF-1 activity in these cells

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Roberts, Tara Laurine. "Cellular responses to immunostimulatory DNA /." [St. Lucia, Qld.], 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe18175.pdf.

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Fallon, Michael P. "Tracking cellular phones with UAV's." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1995. http://handle.dtic.mil/100.2/ADA301710.

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Pruitt-Billingsley, Rachel L. "Analysis of digital cellular standards." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1996. http://handle.dtic.mil/100.2/ADA313554.

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Thesis (M.S. in Systems Technology (Command, Control and Communications))Naval Postgraduate School, June 1996.
Thesis advisor(s): Dan C. Boger, Vicente Garcia. "June 1996." Bibliography: p. 57-58. Also Available online.

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Gallaher, Jill Bier Martin. "Ion Traffic Across Cellular Membranes." [Greenville, N.C.] : East Carolina University, 2010. http://hdl.handle.net/10342/2786.

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Rangineni, Kiran. "Multihop Concept in Cellular Systems." Thesis, University of Gävle, Department of Technology and Built Environment, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-700.

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Abstract:

We are very thirsty in terms of everything to fulfil our needs in a sophisticated way, and this leads me choose the so called master thesis titled “Multihop Concept in Cellular Systems”.

This thesis introduces an approach towards the integration of relaying or multihop scheme in the next generation of cellular networks. In a multihop cellular architecture, the users send their data to the base station via relay station or with direct communication to the base station. These relay stations can either be the nomadic, fixed at specific location or users’ mobile station (i.e. mobile relay station). The main objective of this paper is to compare the difference between the relaying network architecture with different channel bandwidth as well as their performance gain. For this we integrate the relay station into conventional cellular networks using IEEE 802.16j (One of the standard introduced relay station concept in WiMAX) OFDMA (Orthogonal Frequency Division Multiple Access is a transmission technique that is based on many orthogonal subchannels (set of carriers) that transmits simultaneously). The results show that under certain conditions the throughput and coverage of the system has been increased with the introduction of the relay station in to cellular base station zone.

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Kowalewski, Jacob. "Mathematical Models in Cellular Biophysics." Licentiate thesis, KTH, Applied Physics, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4361.

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Cellular biophysics deals with, among other things, transport processes within cells. This thesis presents two studies where mathematical models have been used to explain how two of these processes occur.

Cellular membranes separate cells from their exterior environment and also divide a cell into several subcellular regions. Since the 1970s lateral diffusion in these membranes has been studied, one the most important experimental techniques in these studies is fluorescence recovery after photobleach (FRAP). A mathematical model developed in this thesis describes how dopamine 1 receptors (D1R) diffuse in a neuronal dendritic membrane. Analytical and numerical methods have been used to solve the partial differential equations that are expressed in the model. The choice of method depends mostly on the complexity of the geometry in the model.

Calcium ions (Ca²⁺) are known to be involved in several intracellular signaling mechanisms. One interesting concept within this field is a signaling microdomain where the inositol 1,4,5-triphosphate receptor (IP₃R) in the endoplasmic reticulum (ER) membrane physically interacts with plasma membrane proteins. This microdomain has been shown to cause the intracellular Ca²⁺ level to oscillate. The second model in this thesis describes a signaling network involving both ER membrane bound and plasma membrane Ca²⁺ channels and pumps, among them store-operated Ca²⁺ (SOC) channels. A MATLAB^® toolbox was developed to implement the signaling networks and simulate its properties. This model was also implemented using Virtual cell.

The results show a high resemblance between the mathematical model and FRAP data in the D1R study. The model shows a distinct difference in recovery characteristics of simulated FRAP experiments on whole dendrites and dendritic spines, due to differences in geometry. The model can also explain trapping of D1R in dendritic spines.

The results of the Ca²⁺ signaling model show that stimulation of IP3R can cause Ca²⁺ oscillations in the same frequency range as has been seen in experiments. The removing of SOC channels from the model can alter the characteristics as well as qualitative appearance of Ca²⁺ oscillations.

Cellulär biofysik behandlar bland annat transportprocesser i celler. I denna avhandling presenteras två studier där matematiska modeller har använts för att förklara hur två av dess processer uppkommer.

Cellmembran separerar celler från deras yttre miljö och delar även upp en cell i flera subcellulära regioner. Sedan 1970-talet har lateral diffusion i dessa membran studerats, en av de viktigaste experimentella metoderna i dessa studier är fluorescence recovery after photobleach (FRAP). En matematisk modell utvecklad i denna avhandling beskriver hur dopamin 1-receptorer (D1R) diffunderar i en neural dendrits membran. Analytiska och numeriska metoder har använts för att lösa de partiella differentialekvationer som uttrycks i modellen. Valet av metod beror främst på komplexiteten hos geometrin i modellen.

Kalciumjoner (Ca2+) är kända för att ingå i flera intracellulära signalmekanismer. Ett intressant koncept inom detta fält är en signalerande mikrodomän där inositol 1,4,5-trifosfatreceptorn (IP3R) i endoplasmatiska nätverksmembranet (ER-membranet) fysiskt interagerar med proteiner i plasmamembranet. Denna mikrodomän har visats vara orsak till oscillationer i den intracellulära Ca2+-nivån. Den andra modellen i denna avhandling beskriver ett signalerande nätverk där både Ca2+-kanaler och pumpar bundna i ER-membranet och i plasmamembranet, däribland store-operated Ca2+(SOC)-kanaler, ingår. Ett MATLAB®-verktyg utvecklades för att implementera signalnätverket och simulera dess egenskaper. Denna modell implementerades även i Virtual cell.

Resultaten visar en stark likhet mellan den matematiska modellen och FRAP-datat i D1R-studien. Modellen visar en distinkt skillnad i återhämtningsegenskaper hos simulerade FRAP-experiment på hela dendriter och dendritiska spines, beroende på skillnader i geometri. Modellen kan även förklara infångning av D1R i dendritiska spines.

Resultaten från Ca2+-signaleringmodellen visar att stimulering av IP3R kan orsaka Ca2+-oscillationer inom samma frekvensområde som tidigare setts i experiment. Att ta bort SOC-kanaler från modellen kan ändra karaktär hos, såväl som den kvalitativa uppkomsten av Ca2+-oscillationer.

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Dissertations / Theses on the topic 'Cellular'

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