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Zelensky, Alex N., and Alex Zelensky@anu edu au. "In silico analysis of C-type lectin domains structure and properties." The Australian National University. The John Curtin School of Medical Research, 2005. http://thesis.anu.edu.au./public/adt-ANU20050318.185314.
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Members of the C-type lectin domain (CTLD) superfamily are metazoan proteins functionally important in glycoprotein metabolism, mechanisms of multicellular integration and immunity. This thesis presents the results of several computational and experimental studies of the CTLD structure, function and evolution.¶
Core structural properties of the CTLD fold were explored in a comparative analysis of the 37 distinct CTLD structures available publicly, which demonstrate significant structural conservation despite low or undetectable sequence similarity. Pairwise structural alignments of all CTLD structures were created with three different methods (DALI, CE and LOCK) and analysed manually and using a computational algorithm developed for this purpose. The analysis revealed a set of conserved positions and interactions, which were classified based on their role in CTLD structure maintenance.¶
The CTLD family is large and diverse. To organize and annotate the several thousand of known CTLD-containing protein sequences and integrate the information on their evolution, structure and function a local database and a web-based interface to it were developed. The software is written in Perl, is based on bioperl, bioperl-db and Apache::ASP modules, and can be used for collaborative annotation of any collection of phylogenetically related sequences.¶
Several studies of CTLD genomics were performed. In one such study, carried out in collaboration with the RIKEN structural genomics centre, CTLD sequences from the Caenorhabditis elegans genome were identified and clustered into groups based on similarity. The most representative members of the groups were then selected, which if characterized structurally would tell most about the C. elegans CTLDs and provide templates for homology modelling of all C. elegans CTLD structures.¶
In the other whole-genome study, the CTLD family in the puffer fish Fugu rubripes was analysed using the draft genome sequence. This work extended and complemented three genome-level surveys on human, C. elegans and D. melanogaster reported previously. The study showed that the CTLD repertoire of Fugu rubripes is very similar to that of mammals, although several interesting differences exist, and that Fugu CTLD-encoding genes are selectively duplicated in a manner suggesting an ancient large-scale duplication event. Another important finding was the identification of several new CTLDcps, which had mammalian orthologues not recognized previously.¶
CBCP, a novel CTLD-containing protein highly conserved between fish and mammals with previously unknown domain architecture, was predicted in the Fugu study based solely on ab initio gene models from the Fugu locus and cross-species genomic DNA alignments. To test if the prediction was correct, a full-length cDNA of the mouse CBCP was cloned, its tissue distribution characterized and untranslated regions determined by RACE. The full-length mCBCP transcript is 10 kb long, encodes a protein of 2172 amino acids and confirms the original prediction. The presence of a large N-terminal NG2 domain makes CBCP a member of a small but very interesting family of Metazoan proteins.
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Dahal, Lekh Nath. "Soluble CTLA-4 and immune regulation." Thesis, University of Aberdeen, 2010. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=202565.
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Oliveira, Paulo de Tarso Guerra. "Revisão de modelos CTL." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/45/45134/tde-25032014-092409/.
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Verificação de modelos é uma das mais eficientes técnicas de verificação automática de sistemas. No entanto, apesar de poder lidar com verificações complexas, as ferramentas de verificação de modelos usualmente não fornecem informação alguma sobre como reparar inconsistências nestes modelos. Nesta dissertação, mostramos que abordagens desenvolvidas para a atualização de modelos CTL inconsistentes não são capazes de lidar com todos os tipos de alterações em modelos. Introduzimos então o conceito de revisão de modelos: uma abordagem baseada em revisão de crenças para o reparo de modelos inconsistentes em um contexto estático. Relacionamos nossa proposta com trabalhos clássicos em revisão de crenças. Definimos um operador de revisão de modelos e mostramos que este obedece postulados de racionalidade clássico de revisão de crenças. Propomos um algoritmo de revisão com base no algoritmo utilizado pela abordagem de atualização de modelos. Discutimos sobre problemas e limites do algoritmo proposto, e mostramos que essa estratégia de adaptação não é uma solução apropriada.Model checking is one of the most robust techniques in automated system verification. But, although this technique can handle complex verifications, model checking tools usually do not give any information on how to repair inconsistent system models. In this dissertation, we show that approaches developed for CTL model update cannot deal with all kinds of model changes. We introduce the concept of CTL model revision: an approach based on belief revision to handle system inconsistency in a static context. We relate our proposal to classical works on belief revision. We define an operator for model revision and we show that it obeys the classical rationality postulates of belief revision. We propose an algorithm for model revision based on the algorithm used by the model update approach. We discuss problems and limitations of our proposed algorithm and show that this strategy of adaptation is not an appropriate solution.
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Parsons, Keith. "Bovine CD28, CTLA-4 and their ligands." Thesis, University of Reading, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.484326.
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Meintières, Sophie. "Le rôle de l'apoptose dans les tests in vitro de clastogenèse : apport du modèle CTLL-2 / CTLL-2 Bcl2." Lille 2, 2002. http://www.theses.fr/2002LIL2P014.
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Heibein, Jeffrey Alexander. "Caspase-independent CTL-mediated killing." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ60296.pdf.
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Melo, Félix Joana. "Anti-CTLA-4 antibody / CTLA-4 molecule immuno-modulator mechanisms and its consequences on the reinforcement of anti-melanoma immune responses." Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCC212/document.
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Le mélanome est un cancer de la peau dont l’incidence est en continuelle augmentation dans le monde entier. Des progrès récents dans la compréhension des mécanismes cellulaires complexes régulant l’immunité du cancer ont conduit à l’élaboration de nouvelles stratégies visant des checkpoints spécifiques de la régulation des réponses immunes. Ipilimumab est un anticorps thérapeutique dirigé contre la molécule CTLA-4. Il a permis, chez les patients atteints de mélanome métastatique, d’augmenter la survie globale et a fait l’objet d’une approbation de la FDA en 2011. Cependant cette thérapie ne semble bénéficier qu’à un nombre restreint de patients et souvent de manière retardée. L’identification de marqueurs immunologiques précoces associés à la réponse clinique et à la survie s’avère donc être nécessaire afin d’apporter des éléments d’orientation. Dans ce contexte, nous avons suivi de manière longitudinale, prospective et retrospective une cohorte de 77 patients atteints de mélanome métastatique. Nous nous sommes intéressés dans un premier temps aux molécules sériques reflétant soit l’importance de l’envahissement tumoral (LDH, S100B et MIA) soit l’implication de mécanismes d’échappement immunitaire (MICA soluble et anticorps anti-MICA). Nous montrons une association entre des faibles concentrations sériques de LDH et S100B, soutenues après première et deuxième dose d’ipilimumab, et la réponse au traitement et la survie. De plus, des niveaux élevés de MICA solubles avant le traitement sont associés à une fréquence plus faible de complications à type d’auto-immunité. Nous avons de plus suivi les populations lymphocytaires avec une attention particulière portée sur les compartiments naïf et mémoires T, les facteurs de transcription impliqués dans la différentiation des lymphocytes T mémoires, les cytokines produites et les récepteurs de chimiokines de lymphocytes T. Nos résultats montrent que le taux de lymphocytes avant l’introduction du traitement est un facteur prédictif de meilleure survie et de réponse positive à la semaine 16, indépendamment du taux de LDH et de la corticothérapie. De plus, un effet global de l'ipilimumab sur l'expansion des cellules T mémoires classiques a été observé, associé à la réponse au traitement. En revanche, les fréquences des cellules souches T mémoires (TSCM) récemment décrites diminuent malgré une augmentation de la prolifération, suggérant un processus de différenciation. L'ipilimumab induit aussi l'expansion de lymphocytes T exprimant CXCR3, CCR4 et CCR6, permettant une migration vers la peau et les tissus inflammés, avec augmentation de leur capacité à produire des cytokines effectrices. Une augmentation précoce des cellules T CD8+ exprimant le facteur de transcription Eomes s’est révélée être associée à un contrôle de la maladie. Enfin, et sur la base des résultats précédents, nous avons étudié la capacité des lymphocytes T mémoires de patients à proliférer après stimulation in vitro. Contrairement aux sujets sains, les patients présentent un défaut dans la capacité de prolifération des TSCM qui pourrait être liée à un défaut dans la régulation d’Eomes et Ki-67. Nous proposons ainsi un modèle permettant de suivre de manière précoce les étapes conduisant à la différentiation des TSCM en sous populations mémoires, associées à une réponse clinique sous ipilimumab, et impliquant le facteur de transcription EomesMelanoma is a skin cancer with incidence increasing at dramatic rates worldwide. Ipilimumab, an anti-CTLA-4 therapy developed in the view of counter-balancing the inhibitory role of CTLA-4 in T lymphocytes, was the first immune checkpoint inhibitor demonstrating to extend overall survival in patients with metastatic melanoma, with FDA approval in 2011. However, biomarkers allowing the identification of the subset of patients that will more likely benefit from this immunotherapy or that may allow a good monitoring of patient clinical management during treatment are lacking. The principal objective of this work was to identify potential and early predictive biomarkers of ipilimumab response and/or survival in a cohort of 77 metastatic melanoma patients. Firstly, serum levels of melanoma markers such as LDH, S100B and soluble MICA (and its counter-part anti-MICA antibody), tumour markers associated with tumour development and/or immune escape, were assessed. A correlation between lower baseline levels of LDH and S100B, sustained after the first and second doses of ipilimumab, and treatment response and survival was observed, suggesting their potential utility in treatment monitoring. In addition, higher baseline levels of soluble MICA were found to be associated with a less frequency of immune-related adverse events, which might provide important information for the management of frequent ipilimumab-related adverse events. Secondly, immune markers with a special focus on transcription factors, cytokine secretion and chemokine receptors of T lymphocytes and memory T subsets were assessed. An association between baseline absolute lymphocyte counts and extended overall survival as well as better treatment response was found. In addition, a global effect of ipilimumab on the expansion of conventional memory T cells was observed, which was associated with treatment response. By contrast, frequencies of the recently described stem-cell memory T cells were shown to decrease despite increased proliferation, suggesting a process of differentiation. Additionally, ipilimumab induced the expansion of CXCR3, CCR4 and CCR6-expressing T lymphocytes and effector cytokines secretion capacity. Early increased levels of Eomes-expressing CD8+ T cells were found to be associated with disease control. Lastly, and based on the previous results, we investigated the ability of patients’ memory T cells to proliferate under in vitro stimulation. We found that, in contrast to healthy subjects, patients possess a defect in the ability of stem-cell memory T cells expansion in vitro, that might be related to a defect in Eomes and Ki-67 regulation
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Tipping, Helen. "Regulation of CTLA-4 expression in human T cells." Thesis, University of Birmingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397706.
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Baker, Jennifer. "Understanding control of T cell responses by CTLA-4." Thesis, University of Birmingham, 2012. http://etheses.bham.ac.uk//id/eprint/3788/.
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Cytotoxic T Lymphocyte Associate Antigen 4 (CTLA-4) is an important negative regulator of T-cell activation. The protein is expressed in activated T-cells and can also be found in regulatory T-cells. The mechanism of action of this protein remains controversial; it has typically been associated with a cell intrinsic negative signal however, there is increasing evidence that CTLA-4 may act as an effector molecule. Surprisingly, we find that blocking CTLA-4 in a model of T-cell activation driven by ligand-expressing transfectants has no effect on either proliferation or cytokine production, suggesting that CTLA-4 doesn’t inhibit in this setting. In contrast, blocking CTLA-4 in a dendritic cell based assay enhances proliferation and cytokine production, only when the amount of co-stimulation is limiting. In these experiments CTLA-4 function correlates with decreased expression of B7 ligands on dendritic cells consistent with the removal of ligands by CTLA-4. Furthermore, the addition of CTLA-4 transfected Jurkat cells acts to suppress T cell responses consistent with a role for CTLA-4 as an effector of suppression. Overall our data do not support a role for CTLA-4 in delivering a ligand-dependent cell-intrinsic negative signal and instead suggest a role for CTLA-4 as an effector molecule which inhibits co-stimulation by APC.
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Buonavista-Harmache, Nathalie. "Etude de l'environnement génétique de CTLA-4 et CD28." Aix-Marseille 2, 1995. http://www.theses.fr/1995AIX22026.
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Parmi les molecules accessoires de la presentation, les molecules ctla4/cd28 et leurs ligands b7. 2/b7. 1 paraissent jouer un role essentiel dans l'amplification, le maintien et l'arret de la reponse immunitaire. Dans le but d'etudier l'organisation physique de la region genomique contenant ctla4 et cd28, nous avons sous-clone les regions humaines et murines homologues dans des yacs. Nous avons cartographie ces yacs, puis nous les avons sous-clones en cosmides et organises en contig. Nous avons montre que chez l'homme, ces deux genes sont distants de 110 kb, sont separes par un ilot cpg et presentent un sens de transcription identique. Chez la souris, le plus petit fragment de restriction portant a la fois les genes de ctla4 et cd28 mesure 40 kb. Nous avons ensuite recherche de nouvelles sequences codantes a l'interieur de cette region syntenique. L'hybridation du yac contenant la region genomique murine de ctla4 et cd28 par des sondes cosmidiques de la region humaine homologue, a mis en evidence une nouvelle sequence conservee. Par criblage d'une banque de lymphocytes t actives par la sonde cosmidique correspondante, nous avons isole l'adnc de b23, une phosphoproteine de transport potentiellement impliquee dans la regulation transcriptionnelle. Le sequencage du cosmide a revele l'existence d'une sequence sans intron presentant un orf de 596 pb et presentant 95% d'homologie avec b23. Cette nouvelle sequence susceptible d'etre traduite en proteine tronquee de b23 et conduit a se poser les questions de sa nature et de sa fonction dans cette region
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Wang, XiongBiao. "CTLA-4 expression, regulation and associations in autoimmune myasthenia gravis /." Stockholm, 2003. http://diss.kib.ki.se/2003/91-7349-684-7/.
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Schueller, Roland. "Insights into the RNA Polymerase CTD code." Diss., Ludwig-Maximilians-Universität München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-165651.
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Gupta, J. P. "The realisation of a CTD multiprocessor architecture." Thesis, University of Westminster, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305348.
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SANTOS, Leandro Marcos. "Clortalidona (CTD): polimorfismo, enantiomeria e substâncias relacionadas." Universidade Federal de Alfenas, 2014. https://bdtd.unifal-mg.edu.br:8443/handle/tede/766.
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Neste trabalho serão apresentados os quatro polimorfos do fármaco diurético e anti-hipertensivo Clortalidona, (RS)-2-Cloro-5-(1-hidroxi-3-oxo-2,3-dihidro-1H-isoindol-1-il)benzeno-1-sulfonamida (CTD), ressaltando que todos eles foram elucidados pelo Grupo de Cristalografia da UNIFAL-MG e que o polimorfo mais recentemente elucidado, forma II, é um resultado direto da condução deste trabalho de Mestrado. Será estabelecida uma correlação estrutura/propriedades do estado sólido para explicar as diferenças nos resultados obtidos pela caracterização dos polimorfos I e II da CTD por Espectroscopia de absorção no Infravermelho (IV) e Análises térmicas (TG/DSC) com base nas características estruturais de ambos os polimorfos, evidenciando como o fenômeno do polimorfismo pode impactar e afetar as propriedades físico-químicas de um IFA sólido. Também serão apresentadas duas estruturas cristalinas inéditas do ácido 4’-cloro-3’-sulfamoilbenzofenona carboxílico (CCA), o qual é um produto de hidrólise da CTD e consiste em uma impureza inerente às suas formulações, mas que também é um composto biologicamente ativo e pode atuar como diurético. Além disso, serão apresentadas as rotas sintéticas que resultaram na formação do CCA e de outras duas substâncias relacionadas à CTD, bem como um estudo mecanístico que permite prever e propor a síntese de outros compostos.In this work will be presented the four polymorphs of the diuretic and antihypertensive drug Chlorthalidone, (RS)-2-Chloro-5-(1-hydroxy-3-oxo2,3-dihydro-1H-isoindol-1-yl)benzene-1-sulfonamide (CTD) , noting that all of them were elucidated by the Group of Crystallography of the UNIFAL-MG and polymorph recently elucidated , is a direct result of the conduct of this work of Science Master. There will be correlation structure/properties of solid state to explain the differences in results obtained by the characterization of polymorphs I and II of the CTD by infrared spectroscopy and thermal analysis based on the intrinsic structural features of both polymorphs, showing as the phenomenon of polymorphism can impact and affect the physicochemical properties of a drug. Two novel crystal structures of 4’-chloro-3’-sulfamoylbenzophenone carboxylic acid (CCA) will also be presented. This is a hydrolysis product of CTD and also a biologically active compound that can act as a diuretic. Furthermore, synthetic routes that resulted in the formation of CCA and two other CTD related substances will be presented, as well as a mechanistic study that allows predict and propose the synthesis of other related compounds.
Fundação de Amparo à Pesquisa do Estado de Minas Gerais - FAPEMIG
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Yafei, Zain Al. "Tumour-specific CTLs : what does it take to wake them up?" Thesis, University of Bristol, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.573931.
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The immunosurveillance hypothesis states that the immune system recognises and responds to tumours preventing growth and progression and that tumour- infiltrating CD8+ T cells are essential component. However, most immune-based antitumour therapies have had limited efficacy in controlling tumour growth due to immunosuppression within the tumour microenvironment. Experiments described in this thesis were aimed at understanding mechanisms of tumour- mediated immunosuppression of antitumour CTL responses. Studies utilised a BALB/c mouse model comprising renal carcinoma cells (Renca), expressing the haemagglutinin (HA) protein from influenza virus AlPRl8/H1 NI(PR8) as tumour- specific neo-antigen, and transgenic CL4 CD8+ T cells, expressing a high affinity TcR specific for the dominant Kd-restricted epitope of HA. The data show that CL4 CD8+ T cells undergo productive activation (PA) in the tumour draining lymph nodes resulting in CTL responses. However, following migration into the tumour they lose effector function, which is accompanied by an increase in cell- surface expression of Ly6C. However, if the interaction of Ly6C with its unknown ligand is blocked under conditions that would otherwise result in abortive activation then PA is restored. Other studies revealed that endogenous tumour-infiltrating Iymphocytes (TIL) could suppress CL4 CTL activity by elaborating adenosine via CD39 and CD73 ecto-enzymes. However, suppression was prevented by antagonising the adenosine receptors. Further investigations revealed that expression of CD39 and CD73 by endogenous TIL is controlled by TGF-~. Several distinct populations of tumour-infiltrating myeloid-derived suppressor cells (Ti-MDSC) were also characterised based on cell-surface expression of different levels of Ly6C and Ly6G glycoproteins. Not only do their phenotypic profile and relative proportion change over time as the tumours progress, but these Ti-MDSC also express CD39 and CD73. These findings demonstrate that various mechanisms of immunosuppression operate within the tumour microenvironment. Therefore, although targeting individual mechanisms may potentially alleviate some of the suppression; enabling partial restoration of CTL activity, it is likely that only by targeting multiple mechanisms will we be able to fully restore CTL activity to such an extent that the tumour is eradicated. Abstract word count: 325
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Mead, Karen Ingrid. "Role of protein trafficking in the regulation of CTLA-4 expression." Thesis, University of Birmingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.404056.
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Lozano, Viviane Furlan. "Análise de polimorfismo no gene CTLA-4 em pacientes com paracoccidioidomicose." reponame:Repositório Institucional da UnB, 2008. http://repositorio.unb.br/handle/10482/3528.
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A proteína CTLA-4 é expressa principalmente em células T ativadas, possuindo um papel fundamental na resposta imune, exercendo efeito regulador na ativação de célula T através da sua ligação com as moléculas da família B7, as quais são expressas em células apresentadoras de antígenos. Polimorfismos no gene CTLA-4 têm sido associados a várias doenças autoimunes e, recentemente, à doenças neoplásicas e infecciosas. A paracoccidioidomicose é uma micose sistêmica, causada pelo fungo dimórfico Paracoccidioides brasiliensis. As manifestações clínicas desta doença estão associadas a vários fatores como a secreção alterada de citocinas, hipergamaglobulinemia, e depressão da imunidade celular, sendo que a hiporesponsividade é também atribuída a uma maior expressão de CTLA-4 em células T de pacientes quando comparados a indivíduos controles. O presente trabalho teve por objetivo estudar a possível associação dos SNPs -318C/T na região promotora e +49A/G do éxon 1 do gene CTLA-4 com a PCM. Para isso, 74 pacientes com PCM e 76 indivíduos controles provenientes de regiões distintas do País tiveram suas freqüências alélicas e genotípicas determinadas. A comparação das freqüências genotípicas e alélicas, entre os grupos pacientes e controles, não mostrou diferenças significativas que pudessem associar o polimorfismo dos SNPs -318 e +49 do gene CTLA-4 com a PCM. A análise dos resultados referentes às freqüências haplotípicas obtidas mostrou que existe um forte desequilíbrio de ligação (D'=1) entre os SNPs -318 e +49 para os dois grupos estudados. Porém, a análise realizada não revelou diferenças significativas entre as freqüências haplotípicas dos grupos. Outro ponto importante analisado foi o estudo da estrutura genética (ancestralidade) dos grupos de pacientes e controles. Verificou-se que há predomínio de ancestralidade européia sobre as ancestralidades ameríndia e africana em ambos os grupos. Através desses resultados foi possível determinar que a população utilizada no estudo é geneticamente homogênea, e que o resultado negativo da associação detectado para o gene CTLA-4 e a PCM não está relacionado a ancestralidade da amostragem. Este trabalho demonstra que não foi observada nenhuma associação entre o polimorfismo dos SNPs -318 e +49 do gene CTLA-4 com a resistência e/ou susceptibilidade à Paracoccidioidomicose.
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Eriksson, Marcus. "A CLP(FD)-based model checker for CTL." Thesis, Linköping University, Department of Computer and Information Science, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-109.
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Model checking is a formal verification method where one tries to prove or disprove properties of a formal system. Typical systems one might want to prove properties within are network protocols and digital circuits. Typical properties to check for are safety (nothing bad ever happens) and liveness (something good eventually happens).
This thesis describes an implementation of a sound and complete model checker for Computation Tree Logic (CTL) using Constraint Logic Programming over Finite Domains (CLP(FD)). The implementation described uses tabled resolution to remember earlier computations, is parameterised by choices of computation strategies and can with slight modification support different constraint domains. Soundness under negation is maintained through a restricted form of constructive negation.
The computation process amounts to a fixpoint search, where a fixpoint is reached when no more extension operations has any effect. As results show, the choice of strategies does influence the efficiency of the computation. Soundness and completeness are of course independent of the choice of strategies. Strategies include how to choose the extension operation for the next step and whether to perform global or local rule instantiations, resulting in bottom-up or top-down computations respectively.
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Ming, Marin. "Induction of CTL responses by plasmid DNA immunization." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0004/MQ45528.pdf.
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Attaran, Amir. "CTL cytotoxicity and the cytoskeleton : a microscopical study." Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308607.
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Pfafferott, Katja J. C. E. "CTL escape and immune control in HIV-I." Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419320.
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Broadbent, Heather. "A CTD Biotag for Mid-sized Marine Predators." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/3992.
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Biologging tools for investigating the study of fine-scale linkages between animal behavior and the physical microstructure of the marine habitat are technically limited by substantial size, high cost or low sensor resolution. However, recent advances in electronic technologies and process techniques present attractive alternatives to current tag designs. Motivated by the need for a low-cost, compact CTD biotag for medium-sized marine animals, the University of South Florida Center for Ocean Technology developed a multi-sensor biotag for quantitative measurements of ocean salinity. This dissertation describes the development and performance of a novel CTD biotag used for animal-borne measurements of the physical microstructure of marine ecosystems.
Printed circuit board processes were used to fabricate a liquid crystal polymer- based conductivity, temperature and depth sensor board. Tests performed in the laboratory exhibited good sensor repeatability between the measured and the predicted variables indicating that the initial design and fabrication process is suitable for the construction of a CTD sensor board. The conductivity cells showed good sensor integrity for the entire conductivity range (0- 70 mS/cm), thus demonstrating the potential for a highly resolved salinity system.
The CTD sensor board was integrated into two initial multi-sensor biologging systems that consisted of reconfigurable modular circuit boards. The design and initial performance of a 4-electrode conductivity cell circuit was discussed and preliminary tests showed a sensor accuracy of 0.0161 mS/cm. A potential packaging material was analyzed for use on the temperature and pressure sensors and initial tests showed good sensor sensitivities (-2.294 °C/kohms and 1.9192 mV/dbar, respectively).
Underwater packaging of the biotag was presented in this work along with three different field observations. Vertical profiles of conductivity, temperature and depth in the Gulf of Mexico were obtained and compared to a commercial instrument. On the West Florida shelf, conductivity, temperature, depth and salinity data were obtained from loggerhead turtle deployments. Data collected showed that the tagged turtle encountered a highly variable salinity range (30.6- 35.3) while at depth (20 m). This data trend captured was in agreement with shelf characteristics (tidal fluxes and water mass features) and moored instruments. Finally, observations that were undertaken in Bayboro Harbor showed no biofouling to the conductivity electrodes during a 14 day deployment. This biotag is the first to use a PCB-based low-cost CTD to collect animal-borne salinity measurements.
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Kuznetsova, Olga. "Regulation of human RNA polymerase II CTD modifications." Thesis, University of Oxford, 2015. http://ora.ox.ac.uk/objects/uuid:e745b5b6-8a4a-4b7a-81d7-499bca8bfea1.
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Transcription of human protein-coding genes and most small nuclear RNA genes is mediated by RNA Polymerase II (Pol II). During a cycle of transcription, Pol II recruits a variety of factors that facilitate transcription elongation, RNA processing and termination, through its long, unstructured C-terminal domain (CTD). The CTD in humans comprises 52 tandem heptapeptide repeats with the consensus sequence Y1S2P3T4S5P6S7. Each amino acid of the heptapeptide can be chemically modified, which influences the recruitment of other protein factors to the transcription machinery. Not all enzymes that modify the CTD have been discovered. Recent studies have identified a novel CTD phosphatase: RPAP2 in humans and its yeast homologue Rtr1, which dephosphorylate phospho-Ser5 of the heptapeptide repeats. RPAP2 has been shown to stimulate 3' end cleavage of nascent snRNAs through recruitment of the Integrator complex, and unpublished work suggests the involvement of RPAP2 in regulating vertebrate developmental programs. However, the exact mechanisms that regulate the function of human RPAP2, and thus impact on CTD modification, are not well-understood. This thesis presents a novel mechanism whereby RPAP2 recruits protein phosphatase 1 (PP1) to snRNA genes, where PP1 is postulated to activate P-TEFb to phosphorylate Ser2 of the CTD. At the same time, P-TEFb may have a role in activating the phosphatase activity of RPAP2. Furthermore, RPAP2 itself is shown to be recruited to a number of gene promoters by the RPRD1A protein, which also stimulates its phosphatase activity. RPAP2 was shown to have another role in regulating transcription termination: by recruiting the Integrator complex, which is shown here to mediate termination of snRNA genes, and by a so far unknown mechanism on a long protein-coding gene. An attempt was made to purify and crystallise the human RPAP2 to obtain a crystal structure, however the crystallisation trials were not successful. Finally, a correlation was found in human embryonic stem cells and induced pluripotent stem cells between low levels of RPAP2 and high levels of CTD Ser5P, suggesting a potential involvement of RPAP2 in regulating transcription at a key developmental stage. The results presented here contribute to the understanding of human transcriptional mechanisms and the numerous interactions within the transcription machinery. In particular, the mechanism of terminating the transcription of snRNA genes is identified. An interesting possibility is the regulation of development and stem cell differentiation by RPAP2; however the exact pathways by which this occurs are yet to be discovered.
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Brunner-Weinzierl, Monika. "Die Rolle von CD152 (CTLA-4) bei der Begrenzung von T-Zellantworten." [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=972713417.
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Speck, Uwe. "Beeinflussung antigenspezifischer humaner T-Zellen durch die Blockade von CD152 (CTLA-4)." [S.l.] : [s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=96633809X.
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Brunner-Weinzierl, Monika. "Die Rolle von CD152 (CTLA-4) bei der Begrenzung von T-Zellantworten." Doctoral thesis, Humboldt-Universität zu Berlin, Medizinische Fakultät - Universitätsklinikum Charité, 2004. http://dx.doi.org/10.18452/13941.
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Bei der adaptiven Immunantwort wird ein breites Repertoire an Effektor-T-Zellen gebildet, das sich durch spezifische und vielfältige funktionelle Fähigkeiten auszeichnet. Neben der Aktivierung der Immunantwort werden Mechanismen benötigt, die Immunantworten regulieren und abschalten können, um unerwünschte Immunreaktion zu verhindern. Die Arbeit befasst sich mit der Rolle von CD152 (CTLA-4), einem Homolog zu CD28, bei der Begrenzung von T-Zellantworten. Die Inhibition der Proliferationsbegrenzung der T-Zellen durch CD152 war ursprünglich auf eine späte Abschaltung der T-Zellproliferation zurückgeführt worden. Wir konnten zeigen, dass CD152 bereits die T-Zellaktivierung abschalten kann und somit die Aktivierungsschwelle der T-Zelle heraufsetzt. Wir konnten auch zeigen, dass CD152 die frühe T-Zellproliferation auf zwei Ebenen inhibiert: Durch die Transkriptionsinitiierung des autologen, Proliferation-induzierenden Zytokins IL-2 und durch die Expression von G1-Kinasen, die für das voranschreiten des Zellzyklus unerläßlich sind. Bisher war es nicht möglich, individuelle, CD152-oberflächen-exprimierende T-Zellen zu detektieren. Um die Expression von CD152 auf der Oberfläche von T-Zellen zu analysieren, haben wir eine sensitive Färbemethode für Oberflächen-exprimiertes CD152 etabliert. Wir konnten damit zeigen, dass während einer antigen-spezifischen Stimulation Zellmembran-gebundenes CD152 lediglich auf einer Subpopulation von aktivierten Zellen (CD152+ T-Zellen) exprimiert wird. Isolierte, aktivierte CD152+ T-Zellen waren im Gegensatz zu aktivierten CD152- T-Zellen bei Restimulation in ihrer Proliferation inhibiert. Dies zeigt auch, dass CD152 in der Lage ist, bereits aktivierte T-Zellen zu inhibieren. Die heterogene Expression von CD152 auf der Oberfläche lässt vermuten, dass die CD152 exprimierenden Zellen, wenn sie ein CD152-Signal bekommen, eine andere Zelldifferenzierung einschlagen als Zellen ohne CD152. Wiederholte oder chronische Aktivierung von Th-Zellen führt zu einer Form von Apoptose, dem Aktivierungs-induzierter Zelltod, gegen den Th2-Zellen resistent sind. Aktivierte Th2-Zellen exprimieren, im Gegensatz zu Th1-Zellen, häufiger CD152 auf ihrer Oberfläche. Wir konnten zeigen, dass CD152-Kreuzvernetzung von aktivierten T-Zellen direkt Resistenz gegen Apoptose vermittelt. Dies geschieht, indem ein Signaltransduktionsmolekül, die PI3´Kinase, aktiviert wird. Dies führt zur Inaktivierung von Apoptose-unterstützenden Molekülen (Phosphorylierung von FKHRL1 und Herunterregulation von FasL) und zur Induktion des Apoptose-verhindernden Moleküls Bcl-2. Vermeidung von Apoptose ist eine zentrale Voraussetzung zur Induktion von Gedächtniszellen. CD152 exprimierende Zellen wären somit gute Kandidaten, um zu Gedächtniszellen zu differenzieren. Um die Rolle von CD152 bei der späten T-Zelldifferenzierung in vivo untersuchen zu können, wurde das CD152 Gen konditionell in der Maus mutagenisiert.During adaptive immune responses a broad repertoire of effector T-cells is generated, characterized by diverse functional capabilities. Besides activation of the immune response other mechanisms are needed in order to regulate and terminate responses, thus preventing unwanted immune reactions. Here I focus on the role of CD152 (CTLA-4), a homologue of CD28, in the limitation of T-cell responses. Inhibition of T-cell-proliferation by CD152 was originally attributed to a late regulation of the T-cell proliferation. We now show that CD152 is already able to prevent the activation of T-cells and to set the threshold for their activation. We also show that CD152 inhibits T-cell activation in two ways: It inhibits the induction of the growth-factor IL-2 and it inhibits the expression of G1-kinases mandatory for the progression of the cell cycle. Until now, it has not been possible to detect individual T-cells expressing CD152 at their surface. To analyze the expression of CD152 at the surface of individual cells, we developed a sensitive staining method. Using this technique we could show that antigen-specific stimulation of T-cells leads to the expression of surface-bound CD152 only on a fraction of the activated T-cells. Isolated, activated CD152+ T-cells were inhibited in their proliferation whereas CD152- T cells were not. This also shows that CD152 is indeed able to inhibit already activated T-cells. The heterogenous expression of CD152 at the cell surface of already activated T-cells also suggests that CD152+ T-cells will differentiate differently compared to CD152-T-cells. Repeated or chronic activation of Th-cells leads to one form of apoptosis, activation-induced cell death (AICD), against which Th2-cells are resistant. Activated Th2-cells express surface CD152 at higher frequencies than Th1-cells. We show here, that CD152-crosslinking of activated T-cells directly induces resistance against AICD by a mechanism requiring PI3´kinase. This leads to the inactivation of pro-apoptotic molecules (phosphorylation of FKHRL1 and downregulation of FasL). It also leads to the induction of the survival molecule Bcl-2. Prevention of apoptosis is a central prerequisite for the generation of memory cells. Therefore, surface CD152+ T-cells might be good candidates to differentiate into memory cells. To investigate the role of CD152 during the differentiation of T-cells in vivo, the CD152 gene was conditional mutagenese of the CD152 gene was generated.
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Khor, WeeLiam. "Crack tip opening displacement (CTOD) in single edge notched bend (SEN(B))." Thesis, Brunel University, 2018. http://bura.brunel.ac.uk/handle/2438/16198.
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This thesis investigates the quantity Crack Tip Opening Displacement (CTOD) as a means to assess fracture toughness when measured in the Single Edge Notched Bend (SENB) specimen setup. A particular objective is to assess the effectiveness of the test when used for high strain-hardening materials (e.g. stainless steels). This has been an increasing concern as the current available methods were generally designed for lower strain hardening structural steel. Experimental work on CTOD tests included silicone casting of the crack, and constant displacement tests were also performed. The silicone castings enable physical measurement of the crack under an optical microscope. Results from a series of Finite Element (FE) models were validated from the experiments. δ5 surface measurements were obtained using Digital Image Correlation (DIC) as a courtesy of TWI, which were compared to surface CTOD measurements from the silicone castings. In addition to the experiments and Finite Element modelling, archived test data from TWI was processed, showing analytical differences between current Standard CTOD equations. CTOD calculations from BS 7448, ISO 12135, ASTM E1820 and WES 1108 were compared to the experimental and FE modelling results. For high strain hardening material, CTOD predicted by Standard equations (apart from those in BS 7448 and single point CTOD from ISO 12135) were lower than the values determined from silicone measurements and modelling. This potentially leads to over conservative values to be used in Engineering Critical Assessments (ECA) or material approval. Based on a series of different strain hardening property models, a relationship between strain hardening and the specimen rotational factor, rp was established. An improved equation for the calculation of CTOD is proposed, which gave good estimation of the experimental and Finite Element modelling results. The improved equation will be proposed for future amendments of the ISO 12135 standard. The results of this research enable the accurate fracture characterisation of a range of engineering alloys, with both low and high strain hardening behaviour in both the brittle and ductile fracture regime.
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Kaur, Satdip. "Role of the CTLA-4 C-terminus in regulating its intracellular trafficking." Thesis, University of Birmingham, 2014. http://etheses.bham.ac.uk//id/eprint/4903/.
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CTLA-4 is an important inhibitor of T cell immune responses. The location of CTLA-4 in intracellular vesicles is the most dominating aspect of its biology, yet the significance of this at the functional level remains to be completely understood. I have therefore investigated the role of the CTLA-4 cytoplasmic domain in the intracellular trafficking of the receptor with particular emphasis on sorting signals encoded within this domain. We found that CTLA-4 was located in punctate intracellular vesicles in transfected cells, activated T cells and in regulatory T cells. CTLA-4 internalisation from the cell surface was clathrin dependent and was driven by the YVKM motif encoded within the cytoplasmic domain. Post-internalisation CTLA-4 colocalised with markers of late endosomes. Since the degradation process may serve as one of the mechanisms to regulate CTLA-4 expression we investigated this further and found that ubiquitination of intracellular lysine residues targets CTLA-4 to lysosomes. The ability of CTLA-4 to recycle was dependent on the YVKM motif and subtle changes in this motif reduced recycling efficiency. Moreover, in the absence of lysine residues CTLA-4 recycling was enhanced. CTLA-4 transendocytosis was conserved through evolution but the exact sorting signals required for this function remain to be identified. Overall this thesis emphasises the importance of the CTLA-4 cytoplasmic domain in regulating its intracellular trafficking.
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Aguiar, Juliano de. "CaracterizaÃÃo de Sinais de EmissÃo AcÃstica em Ensaios CTOD por AnÃlise Fractal." Universidade Federal do CearÃ, 2004. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=7343.
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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorA pesquisa teve como objetivo correlacionar diferentes defeitos e suas criticidades, em corpos de prova de aÃo ASTM A516 grau 60 para ensaio CTOD, cujos detalhes foram feitos no metal de base, no metal de solda e na zona termicamente afetada de uma junta soldada, com os sinais de emissÃo acÃstica obtidos durante os ensaios. Quatro mÃtodos de anÃlise fractal foram utilizados: anÃlise re-escalada de Hurst (R/S), dimensÃo de contagem de caixas, dimensÃo de cobetura mÃnima e anÃlise de flutuaÃÃo sem tendÃncias (DFA). Um nÃmero mÃnimo de pontos necessÃrios para a obtenÃÃo dos expoentes associados a cada mÃtodo de anÃlise foi determinado para os vÃrios sinais, bem como o efeito de diferentes mÃtodos de filtragem nesses expoentes. Verificou-se que nenhum dos mÃtodos isoladamente conseguiu caracterizar os defeitos nem os regimes de carregamento. Entretanto, utilizando-se representaÃÃes bidimensionais de todos os expoentes juntamente com o desvio padrÃo dos sinais foi possÃvel estabelecer, de forma satisfatÃria, uma caracterizaÃÃo hierÃrquica dos defeitos e regimes de carregamento.
The research aims to correlate different defects and their criticidades in specimens of ASTM A516 grade 60 CTOD test, details of which were made in the base metal in the weld metal and heat affected zone of welded joint with acoustic emission signals obtained during the tests. Four fractal analysis methods were applied: re-scaled analysis Hurst (R / S), the box counting dimension, cobetura minimum dimension and analysis of fluctuation without bias (DFA). A minimum number of points required to obtain the exponent associated with each method of analysis was determined for the various signals and the effect of different filtering methods such exponents. It was found that none of the methods alone failed to characterize or defects charging schemes. However, using two-dimensional representations of all the exponents with the standard deviation of signals could be made in a satisfactory way, a hierarchical characterization of defects and charging systems.
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Wang, Chunjing. "Role of CTLA-4 in CD4 T cell homeostasis, function and differentiation." Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10046608/.
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CTLA-4, as a member of CD28 receptor family, has been widely accepted as an important negative regulator of immune responses and plays an essential role in maintaining self-tolerance. Accordingly congenital ablation of the CTLA-4 gene in mice causes uncontrolled lymphoproliferation and extensive autoimmune tissue destruction. Here we demonstrate that CTLA-4 deficiency not only results in hyperactivated conventional T cells, but also causes an increased regulatory T cell (Treg) compartment, which can be largely attributed to enhanced proliferation of Treg in the periphery. Through short-term anti-CTLA-4 antibody treatment of wildtype and CD28-deficient mice, we reveal CTLA-4-mediated control of Treg proliferation is dependent on control of CD28 signaling. In addition to regulating Treg proliferation, data from an adoptive transfer model of type 1 diabetes suggests CTLA-4 is an important component of Treg suppression in vivo. For years, CTLA-4 was thought to function extrinsically in Treg but intrinsically in conventional T cells. In this project, we show CTLA-4 expressed on conventional T cells can also work in a cell extrinsic manner. In this way, antigen-specific-CTLA-4-sufficient conventional T cells can restrain the proliferative responses of CTLA-4-deficient ones upon co-transfer. However CTLA-4-sufficient conventional T cells cannot replace Treg for the maintenance of peripheral tolerance. Accordingly, CTLA-4-sufficient conventional T cells only partially control lymphoproliferative disease induced by CTLA-4-/- bone marrow cells whereas its-sufficient Treg completely prevent disease in this setting. In addition, we demonstrate that the CTLA-4/CD28 pathway also plays a key role in controlling follicular helper T cell differentiation and subsequently germinal center B cell development. Taken together, our data in this study yield new insights into how the CTLA-4 pathway controls immune responses in vivo.
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Aguiar, Juliano de. "Caracterização de sinais de emissão acústica em ensaios CTOD por análise fractal." reponame:Repositório Institucional da UFC, 2004. http://www.repositorio.ufc.br/handle/riufc/2538.
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AGUIAR, J. Caracterização de sinais de emissão acústica em ensaios CTOD por análise fractal. 2004. 138 f. Dissertação (Mestrado em Engenharia e Ciência de
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The research had the objective of correlating different defects and their criticalities in specimens of ASTM A516 grade 60 carbon steel for CTOD tests, whose notches were made in the base metal, in the weld metal and in the thermally affected zone of a welded joint, with the acoustic emission signals obtained during the test. Four methods of fractal analysis were used: rescaled Hurst analysis (R/S), boxcounting dimension, minimal cover dimension an detrended fluctuation analysis (DFA). A minimal number of points necessary for obtaining the exponents associated with each of the different filtering methods on these exponents. It has been verified that none of the methods alone has been able to characterize either the defects, or the loading regimes. However, by using the bi-dimensional representations of all the exponents, together with the standard deviation of the signals, it has been possible to establish satisfactorily a hierarchical characterization of the defects and the loading regimes.
A pesquisa teve como objetivo correlacionar diferentes defeitos e suas criticidades, em corpos de prova de aço ASTM A516 grau 60 para ensaio CTOD, cujos entalhes foram feitos no metal de base, no metal de solda e na zona termicamente afetada de uma junta soldada, com os sinais de emissão acústica obtidos durante os ensaios. Quatro métodos de análise fractal foram utilizados: análise re-escalada de Hurst (R/S), dimensão de contagem de caixas, dimensão de cobertura mínima e análise de flutuação sem tendências (DFA). Um número mínimo de pontos necessários para a obtenção dos expoentes associados a cada método de análise foi determinado para os vários sinais, bem como o efeito de diferentes métodos de filtragem nesses expoentes. Verificou-se que nenhum dos métodos isoladamente conseguiu caracterizar os defeitos nem os regimes de carregamento. No entanto, utilizando-se representações bidimensionais de todos os expoentes juntamente com o desvio padrão dos sinais foi possível estabelecer, de forma satisfatória, uma caracterização hierárquica dos defeitos e regimes de carregamento.
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BALZANO, CHRISTINE. "Ctla-4 : de l'adn a la proteine, du gene a la fonction." Aix-Marseille 2, 1992. http://www.theses.fr/1992AIX22003.
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Ctla-4, isolee par une approche de genetique reverse, appartient au sous-groupe des molecules a domaine v unique de la superfamille des immunoglobulines. Un anticorps monoclonal de souris a permis d'etablir un poids moleculaire de 26 et 40 kd pour le monomere et le dimere humain ctla-4, respectivement, et de mettre en evidence l'expression de cette molecule a la surface des lymphocytes t actives. Dans la famille des igs ctla-4 est plus particulierement homologue a la molecule d'activation lymphocytaire t cd28 en terme de structure proteique, de distribution tissulaire et d'organisation genomique. De plus leurs genes sont co-localises sur les chromosomes 1c de souris et 2q33 d'homme, et sont distants sur un meme chromosome artificiel de levure d'au plus 150 kb. Enfin, ctla-4 et cd28 partagent un meme ligand, b7/bb1. L'ensemble des homologies et la proximite genique suggerent que ctla-4 et cd28 sont issus d'un gene ancestral commun dont la duplication aurait precede la speciation et soulevent la question du role physiologique de ctla-4
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Yaworski, Rebecca. "The Regulation of Hepatic Choline Transport." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/37018.
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Choline is an essential nutrient, in the liver it is a precursor necessary for the synthesis of phosphatidylcholine (PC) and is also required as a methyl donor towards the synthesis of betaine and later regeneration of S-adenomethionine (SAM). Choline deficiency is known to trigger the development of non-alcoholic fatty liver disease and affect mitochondrial homeostasis along with a myriad of methylation related regulatory mechanisms. Because of its importance in maintaining liver lipid and mitochondrial homeostasis, choline metabolism has been well characterized with the exception of its transport. The identification of choline transporters has only been recently discovered and because of this, relatively little is known about their expression and regulation.
This study has established that choline transporter like proteins 1-5 (CTL1-5) is an intermediate affinity transport system responsible for ~80% of hepatic choline uptake with a smaller percentage accomplished through the low affinity organic cation transporter 1-3/N1-2 (OCT1-3/N1-2) transporters. SLC44A1 expression and choline incorporation have been shown to follow a 24 hour rhythmic trend suggesting the presence of a circadian regulatory mechanism. This finding is supported by the significant decrease in choline expression and aberrant pattern of choline incorporation discovered among rhythmic deficient BMAL-/- mice and through a bioinformatics analysis which revealed the existence of four REV-ERBα consensus sequences. Hepatic SLC44A1 expression and choline incorporation have also been shown to decrease with the onset of obesity. Choline uptake was also shown to decrease following treatment with the free fatty acid oleate. This work increases our knowledge of hepatic choline transport and demonstrates a link between the circadian rhythm and obesity with the hepatic CTL1 transporter.
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Coutzac, Clélia. "Immunomodulation par les anticorps monoclonaux thérapeutiques bloquant CTLA-4 : rôle de la flore intestinale et de ses métabolites." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS396/document.
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Au cours des dernières années, l’immunothérapie a révolutionné le paysage en oncologie. L’anti-CTLA-4 a montré son efficacité sur la survie globale des patients atteints de mélanome métastatique. Cependant, ce traitement présente des limites à son utilisation telles que l'efficacité clinique obtenu chez seulement 20% des patients et la survenue fréquente de colites pouvant être sévères. La recherche de biomarqueurs prédictifs de réponse clinique et/ou de développement de toxicité devient maintenant un enjeu majeur pour sélectionner les patients pouvant avoir un bénéfice à l’utilisation de ces traitements. En partant de l’observation que les colites induites par l’anti-CTLA-4 présentent des similitudes avec les maladies inflammatoires chroniques de l'intestin, nous avons émis l’hypothèse de l’existence d’un microbiote intestinal associé à une dysrégulation du système immunitaire pouvant prédire la réponse clinique et/ou la survenue d’une colite induite par l’anti-CTLA-4. Nous avons montré dans une cohorte de patients atteints de mélanome métastatique et traités par ipilimumab, qu'un microbiote intestinal enrichi en Faecalibacterium et autres Firmicutes est associé à une meilleure survie globale et sans progression ainsi qu'un risque accru de développer une colite. Les patients avec une flore enrichie en Firmicutes présentent également après traitement par ipilimumab, une activation lymphocytaire plus efficace. Par la suite, nous nous sommes intéressés aux métabolites issus du microbiote fécal et leur implication dans la réponse à l'anti-CTLA-4. Le butyrate est le principal métabolite produit par les Firmicutes. Nous avons observé chez la souris, une inhibition de l'efficacité anti-tumorale de l'anti-CTLA-4 lorsqu'elles étaient supplémentées en butyrate. In vivo, nous avons montré que le butyrate inhibe la surexpression sur les cellules dendritiques, des molécules CD80 et CD86 (molécules B7) induite par l'anti-CTLA-4. Cette immaturité des cellules dendritiques entraine un défaut d'activation des lymphocytes T spécifiques d'antigènes dépendant de l'axe CD28/B7 réduisant ainsi l'efficacité anti-tumorale. Chez l'Homme, nous avons valider cette hypothèse en montrant qu'une concentration sérique élevée en butyrate est associée à une diminution de la survie globale et sans progression comparativement aux patients avec un faible niveau de butyrate sérique.Ces travaux mettent en évidence le lien entre la composition du microbiote et les réponses immunologiques au blocage du CTLA-4. Ils apportent une explication sur un lien indirect via le butyrate entre la composition du microbiote intestinal et la réponse anti-tumorale aux immunothérapiesIn the last years, immunotherapy has revolutionized the landscape in oncology. The efficacy of anti-CTLA-4 has been demonstrated by improving overall survival of patients with metastatic melanoma. However, this treatment has limitations to its use such as the clinical efficacy obtained in only 20% of patients and the high incidence of severe colitis. Predictive biomarkers of clinical response and / or toxicity development are mandatory for a better selection of patients who will benefit from this treatment. Based on the observation that anti-CTLA-4-induced colitis has similarities with inflammatory bowel disease, we hypothesized that the gut microbiota associated with dysregulation of the immune system may predict the clinical response and / or occurrence of anti-CTLA-4-induced colitis.In a cohort of patients with metastatic melanoma treated with ipilimumab, we have shown that a gut microbiota enriched with Faecalibacterium and other Firmicutes is associated with a better of overall and progression-free survival as well as an increased risk of developing colitis. Firmicutes-driven microbiota is also associated with an improvement in lymphocyte T activation after ipilimumab treatment. Subsequently, we were interested in microbial metabolites and their involvement in the clinical response to anti-CTLA-4. Butyrate is the main metabolite produced by the Firmicutes. In mice, we observed an inhibition of anti-tumor effect of anti-CTLA-4 in butyrate-supplemented mice. In vivo, we have shown that butyrate inhibits the overexpression on dendritic cells, of CD80 and CD86 molecules (B7molecules) induced by anti-CTLA-4. This immaturity of the dendritic cells leads to a poor signaling of CD28 / B7 axis and activation of antigen-specific T-cells, thereby reducing anti-tumor efficacy. In humans, we validated this hypothesis by showing that a high serum concentration of butyrate is associated with decreased overall and progression-free survival compared to patients with low serum butyrate levels.This studie highlights the link between the composition of gut microbiota and the immunological responses to CTLA-4 blockade. They provide an explanation of an indirect link via butyrate, between the composition of the gut microbiota and the anti-tumor response to immunotherapies
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Lima, Marcus Vinícius Alves. "Avaliação fenotípica e funcional dos linfócitos T citotóxicos de indivíduos infectados pelo HTLV-1 com diagnóstico de HAM/TSP." Centro de Pesquisas Gonçalo Moniz, 2014. https://www.arca.fiocruz.br/handle/icict/8689.
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Fundação Oswaldo Cruz. Centro de Pesquisa Gonçalo Moniz. Salvador, BA, Brasil
O Brasil representa uma das áreas endêmicas para o vírus linfotrópico de células T humanas do tipo 1 (HTLV-1) e a cidade de Salvador, Bahia, possui a maior prevalência nacional da infecção por este retrovírus (1,8%), com cerca de 50.000 pessoas infectadas. O HTLV-1 foi o primeiro retrovírus humano descrito e está classicamente associado à leucemia/linfoma de células T do adulto (ATLL) e à mielopatia associada ao HTLV-1/paraparesia espástica tropical (HAM/TSP). A HAM/TSP é uma doença inflamatória do sistema nervoso central, cujos mecanismos imunopatogênicos não estão completamente elucidados. O papel dos linfócitos T citotóxicos na patogênese desta doença ainda não está bem definido. Neste estudo, foram avaliados o fenótipo e a função de linfócitos T citotóxicos de pacientes infectados pelo HTLV-1 com HAM/TSP. Ensaios de imunofenotipagem por citometria de fluxo foram conduzidos para avaliar a proporção das subpopulações de memória dos linfócitos T citotóxicos e mensurar potencial citotóxico destas células. Foram analisados 13 indivíduos não infectados e 49 infectados pelo HTLV-1 (18 sem mielopatia - ASS, 6 diagnosticados como HAM/TSP provável - HAM-PB - e 25 como HAM/TSP definido - HAM-D). Os indivíduos infectados apresentaram aumento da proporção de linfócitos T citotóxicos e de suas subpopulações de memória efetora em detrimento das células naive e de memória central. Não foi observada diferença na distribuição das subpopulações de memória dos CTLs entre os indivíduos infectados pelo HTLV-1. A quantidade de CTLs com atividade de degranulação foi significativamente menor nos pacientes HAM-D em comparação aos indivíduos ASS. O grupo HAM-D também apresentou redução (50%) da produção de IFN-γ pelos CTLs em relação ao grupo ASS. O grupo HAM-PB apresentou resultados similares ao grupo ASS quanto à atividade de degranulação e produção de IFN-γ. Aumento da expressão de IL-15 em células mononucleares do sangue periférico e em células CD14+ foi observado em todos os grupos de pacientes infectados em comparação com os indivíduos soronegativos para o HTLV-1. Estes resultados sugerem que os pacientes infectados pelo HTLV-1 com HAM/TSP apresentam prejuízo da resposta imune celular, caracterizado pela diminuição da quantidade de linfócitos T CD8+ com atividade de degranulação.
Brazil represents one of the largest endemic areas for human T-lymphotropic virus cells type 1 (HTLV-1) infection and associated diseases. Salvador, Bahia, is considered as the Brazilian city with the highest national HTLV-1prevalence (around 1.8% in the general population). HTLV -1 was the first human retrovirus described and is classically associated with adult Tcell leukemia/lymphoma (ATLL) and HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP). HAM/TSP is a chronic and progressive inflammatory disease of the central nervous system and your immunopathogenic mechanisms are not completely understood. The role of cytotoxic T-lymphocytes (CTLs) in the pathogenesis of this disease is still undefined. In this study we evaluated the phenotype and function of cytotoxic Tlymphocytes from HTLV-1-infected patients with HAM/TSP. Assays immunophenotyping by flow cytometry were conducted to assess the proportion of cytotoxic T-lymphocytes memory subsets and the cytotoxic potential of such cells. We analyzed 13 uninfected subjects (controls) and 49 HTLV-1-infected patients (18 without myelopathy (asymptomatic-ASS), 6 diagnosed as probable-HAM/TSP (HAM-PB) and 25 as defined-HAM/TSP (HAMD). Infected patients showed an increased proportion of cytotoxic T-lymphocytes and their subpopulations of effector memory cells at the expense of naive and central memory cells. The distribution of CTLs memory subsets resembled between HTLV-1-infected patients. The amount of CTLs with recent degranulation activity was significantly lower in HAM-D patients when compared to ASS group. The HAM-D group also showed IFN-γ production decrease (50%) by CTLs relative to the ASS group. The degranulation activity and IFN-γ production by cytotoxic T-lymphocytes were similar between the HAM-PB patients and ASS patients. Increased expression of IL-15 on peripheral blood mononuclear cells and CD14+cells was observed in all groups of infected patients when compared to not infected subjects. These results suggest that HTLV-1-infected individuals with HAM/TSP have cellular immune response impaired, characterized by decrease of CD8+ T-lymphocytes with degranulation activity.
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Lingel, Holger [Verfasser]. "CTLA-4-induzierte Signaltransduktion bei der Differenzierung von CD8 + T-Zellen / Holger Lingel." Magdeburg : Universitätsbibliothek, 2018. http://d-nb.info/1155824385/34.
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Ovcinnikovs, Vitalijs. "CTLA-4-mediated trans-endocytosis in the control of T cell co-stimulation." Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10059309/.
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The signal threshold for the activation of a naïve T cell upon recognising its antigen is regulated tightly by the CD28/CTLA-4 - CD80/86 pathway. Within this framework, CTLA-4 has been shown to limit the availability of co-stimulation by physical removal of CD80 and CD86 from the APC, via the mechanism of trans-endocytosis (TE). The study presented in this thesis explores CTLA-4-mediated modulation of CD80 and CD86 as it occurs in vitro and in vivo. It is revealed that regulatory T cells, highly enriched in CTLA-4, are able to rapidly recruit it to the cell surface and trans-endocytose CD80 and CD86 upon stimulation. As a result, Treg, but not Tconv, within hours can significantly reduce the level of co-stimulation on DCs. Although both CD80 and CD86 can be readily taken up by CTLA-4, CD80 is the dominant ligand that it preferentially downregulated from APCs in a competitive scenario. Furthermore, CD28 signalling, in addition to TCR, is identified as a requirement for effective CTLA-4 function. In vivo, co-stimulation is shown to dictate the magnitude of a T cell response in a digital manner. Accordingly, Treg suppress Tconv expansion in a way that is consistent with reduced co-stimulation as a consequence of TE. By using antigen presenting cells that express fluorescently-tagged CD80 and CD86, it is revealed that Treg use CTLA-4 to capture its ligands across tissues in the steady state. Thereby, the phenotype of the APC is constantly modulated. Perturbing CTLA-4 identifies that the lymph node migratory DCs are the main target for CTLA-4 control, while CD80 is confirmed to be the preferred ligand. Finally, Treg-expressed CD80 and CD86 is shown to act as a tuning mechanism that restricts homeostatic activation, suppressive capability and TE. Together, these data provide new insight into how CTLA-4-mediated trans-endocytosis may routinely prevent self-reactive immune activation.
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Elzatma, Essameddin. "Study of the regulatory receptor CTLA-4 (CD152) in human myeloid derived cells." Thesis, University of Essex, 2009. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.548590.
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Saldana, Jose Ignacio. "Generation and analysis of a mouse model for conditional inactivation of CTLA-4." Thesis, Imperial College London, 2007. http://hdl.handle.net/10044/1/11896.
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Dartevelle, Pauline. "La D-cateslytine : un nouvel agent antifongique pour le traitement de la candidose buccale." Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAE004.
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L'utilisation excessive d'agents antifongiques, aggravée par la pénurie de nouveaux médicaments introduits sur le marché, provoque l'accumulation de phénotypes de multi-résistance de nombreuses souches fongiques. Dans ce contexte alarmant, le développement de nouvelles molécules alternatives aux agents antifongiques conventionnels constitue un enjeu majeur de santé publique afin de prévenir l’émergence de nouvelles résistances fongiques pour limiter les problèmes socio-économiques. Dans ce contexte, la cateslytine (CTL), un peptide naturel issu de la maturation endogène de la chromogranine A, et déjà décrit comme un agent antimicrobien efficace contre de nombreux agents pathogènes, dont Candida albicans, présente un intérêt particulier. Dans la présente étude, nous avons ainsi comparé l'activité antimicrobienne de deux conformations de CTL, L-CTL et D-CTL contre différentes souches de Candida. Nos résultats démontrent que D-CTL est l'agent antifongique le plus efficace et le plus sûr. De plus, contrairement à L-CTL, D-CTL n'est pas dégradé par les protéases sécrétées par Candida albicans et est également stable dans la salive. La vidéo-microscopie révèle une invasion rapide de Candida albicans par D-CTL, et démontre l’importance de la division cellulaire pour la propagation de D-CTL d'une cellule mère à une cellule fille. La microscopie électronique en transmission permet d’illustrer la perméabilisation de la membrane fongique induite par les deux peptides. Enfin, nos résultats révèlent un effet antifongique additif de la combinaison entre D-CTL et le voriconazole, un agent antifongique de référence dans le traitement des infections liées à Candida. En conclusion, D-CTL peut être considéré comme un agent antifongique efficace, sûr et stable et pourrait être utilisé seul ou en association avec le voriconazole pour traiter les infections orales liées à Candida et servir dans le futur à l’élaboration de biomatériaux actifsThe excessive use of antifungal agents, compounded by the shortage of new drugs being introduced into the market, is causing the accumulation of multi-resistance phenotypes in many fungal strains. Consequently, new alternative molecules to conventional antifungal agents are urgently needed to prevent the emergence of fungal resistance. In this context, Cateslytin (CTL), a natural peptide derived from the processing of Chromogranin A, has already been described as an effective antimicrobial agent against several pathogens including Candida albicans. In the present study, we compared the antimicrobial activity of two conformations of CTL, L-CTL and D-CTL against various strains of Candida. Our results show that D-CTL was the most efficient and safe antifungal agent. Moreover, in contrast to L-CTL,D-CTL was not degraded by proteases secreted by Candida albicans and was also stable in saliva. Using video-microscopy, we also demonstrated that D-CTL can rapidly enter Candida albicans, but is unable to spread within a yeast colony unless from a mother cell to a daughter cell during cellular division. Besides, transmission electron microscopy illustrated the permeabilization of the fungal membrane induced by both peptides. Finally, we revealed that the antifungal activity of D-CTL could be synergized by voriconazole, an antifungal of reference in the treatment of Candida related infections. In conclusion, D-CTL can be considered as an effective, safe and stable antifungal and could be used alone or in a combination therapy with voriconazole to treat Candida associated infections including oral candidosis
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Zaet, Abdurraouf. "An alternative to conventional antibiotics : a new antimicrobial peptide derived from chromogranin A." Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAE004/document.
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Les peptides antimicrobiens (PAMs) représentent des composants importants de l`immunité innée. Ils sont présents dans la plupart des organismes multicellulaires et constituent la première ligne de défense contre les infections. Ils possèdent un large éventail d`activités, une non-toxicité contre les cellules de l`hôte et des effets synergiques avec les antibiotiques conventionnels. Par conséquent, ils peuvent être d`excellents candidats dans le développement de nouveaux antibiotiques pour lutter contre la résistance de microorganismes. Concernant les PAMs dérivés de la chromogranine A (CgA), la cateslytine (Ctl) présente des activités antimicrobiennes directes et des propriétés immunomodulatrices. Dans ma thèse, j`ai cherché à caractériser l`épipeptide D-Ctl, où tous les résidus en conformation-L ont été remplacés par des résidus en conformation-D. Tout d`abord, la stabilité dans les surnageants bactériens et des dosages de l`activité antimicrobienne ont été réalisés, ainsi que l`analyse de viabilité des cellules et des dosages des cytokines libérées par les cellules immunitaires. L`efficacité de D-Ctl a été comparée à celle de L-Ctl contre des souches bactériennes, puis les CMIs ont été déterminées et comparées dans le cas de combinaisons avec des antibiotiques conventionnels, afin de montrer un effet synergique et/ou additif. De plus, D-Ctl ne déclenche pas de résistance chez E. coli. Des tests de cytotoxicité ont été effectués sur plusieurs types de lignées cellulaires et de PBMCs. Les effets inflammatoires aussi ont été testés. Ensuite, le modèle bactérien E. coli MDR a été utilisé pour des analyses physico-chimiques, telles que la microscopie à épifluorescence, la spectroscopie ATR-FTIR et la microscopie à force atomique. Enfin, le brevet D-Ctl a été déposé en 2016 sous le numéro EP 16306539.4 « Nouveau peptide de cateslytine en conformation D ». En conclusion, D-Ctl est capable de tuer rapidement un large spectre de micro-organismes, et il pourrait potentialiser l`effet antimicrobien de plusieurs antibiotiquesAntimicrobial peptides (AMPs) represent important components of innate immunity. They are present in most multicellular organisms and constitute the first line of defense against infections. They exhibit a large spectrum of activities, a non-toxicity against host cells and synergistic effects with conventional antibiotics. Therefore, they can be as excellent candidates in the development of new antibiotics to fight pathogens resistance. Concerning to AMPs derived from chromogranin A (CgA), Cateslytin (Ctl) represents a new antibiotic, which displays direct antimicrobial activities and immunomodulatory properties. In my thesis, I aimed to characterize the epipeptide D-Ctl, where all (L-conformation) residues were replaced by (D-conformation) residues. Firstly, antimicrobial assays were performed, cells viability, immune assays, and the stability in bacterial supernatant was tested. The efficiency of D-Ctl was compared with L-Ctl against bacterial strains, then MICs were determined and compared with combinations in presence of classical antibiotics in order to show synergistic or/and additive effect. Moreover, D-Ctl does not trigger resistance in E. coli. Also, cytotoxicity assays were performed on several types of cell line and PBMCs. Inflammatory effects were tested too. Then, bacterial model E. coli MDR was used for physicochemical analysis such as epifluorescence microscopy, ATR-FTIR spectroscopy and atomic force microscopy. Finally, D-Ctl patent has been deposited in 2016 under the number EP 16306539.4 “New D-configured cateslytin peptide”. To conclude: D-Ctl is able to rapidly kill a broad spectrum of microorganisms, and it could potentiate the antimicrobial effect of several antibiotics
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Tsegaye, Aster. "T cell dynamics and HIV specific CTL responses in Ethiopians." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2004. http://dare.uva.nl/document/76339.
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Palmowski, Michael J. "Strategies for the induction of epitope-specific polyvalent CTL responses." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249165.
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Frazer, Gordon Lee. "How TCR signal strength controls CTL polarisation for target killing." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/277687.
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Cytotoxic T lymphocytes (CTL) are major effector cells in the adaptive immune response against intracellular pathogens and cancers, killing targets with high precision. Precision is achieved through the specificity of the clonally expressed T cell receptor (TCR). TCRs recognise a specific peptide chain loaded into a major-histocompatability complex, triggering signalling, inducing the CTL to attach and kill target cells. Key stages in this attack are the initial conjugation followed by polarisation and docking of the centrosome to the junction of the two cells, the immune synapse (IS). This focuses secretion of the cytolytic components, perforin and granzyme, from modified lysosomes to kill the target cell. My PhD has utilised amino acid substitutions in the target peptide to alter its signal strength and shown this alters the subsequent killing efficiency of a target population. I developed new imaging and analysis techniques to investigate the effect of TCR signal strength at each step of the killing process. I show the first step, conjugation, is reduced for a percentage of cells with dwell times decreasing as TCR signal strength decreased. The next key step of centrosome polarisation and docking at the IS was also impaired for an increasing proportion of cells as TCR signalling reduced. Impaired centrosome docking reduced efficient granule recruitment to the IS, necessary for target killing. Centrosome docking was linked with the TCR-induced intracellular calcium flux, the duration of which increases with the strength of TCR signalling. This demonstrates how the process of CTL killing can be fine-tuned by the quality of antigen.
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Jonson, Carl-Oscar. "The Importance of CTLA-4 and HLA Class II for Type 1 Diabetes Immunology." Doctoral thesis, Linköping : Univ, 2007. http://www.bibl.liu.se/liupubl/disp/disp2007/med1020s.pdf.
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Stunt, Richard John. "The role of the cytoplasmic domain in the localisation of CTLA-4 and CD28." Thesis, University of Birmingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274324.
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Schmidt, Emily Marta. "Role of the CTLA-4 receptor in regulatory T cell development, homeostasis and function." Thesis, University of Birmingham, 2010. http://etheses.bham.ac.uk//id/eprint/1291/.
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Autoimmunity can occur when self-reactive lymphocytes of the adaptive immune system are activated upon encounter with antigen. This can lead to the development of debilitating and potentially life-threatening autoimmune diseases such as type-1 diabetes, rheumatoid arthritis and multiple sclerosis. Regulatory T cells (Tregs) are a subset of CD4+ T cells that express the lineage-specific transcription factor Foxp3 and exert dominant peripheral tolerance to maintain immune homeostasis. It is therefore important to fully understand the underlying mechanisms of Treg development, homeostasis and function due to the positive and negative effects that therapeutic manipulation could have on this essential T lymphocyte population. Many effector molecules have been proposed to have a central role in regulatory T cell function, and it is now clear that Tregs are equipped with multiple mechanisms by which to exert suppressive function. It has been reported that the cytotoxic T lymphocyte antigen-4 (CTLA-4) receptor is constitutively expressed by regulatory T cells and a role for this molecule in Treg suppression has been suggested. This investigation revealed a role for CTLA-4 in maintaining homeostasis of the peripheral regulatory T cell compartment. In addition, using a transgenic mouse model that permitted the development of antigen-specific Ctla-4-deficient Tregs, a role for the CTLA-4 receptor in Treg suppressive function was identified. The data obtained suggest that the CTLA-4 receptor may function on regulatory T cells by modulating CD80/CD86 co-stimulatory molecule expression by antigen-presenting cells, and hence their capacity to activate conventional T cells to generate effector T cells and instigate an effective immune response.
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Francis, Ore. "Bioinformatics, phylogenetic and biochemical analyses of the proteins of the muskelin/RanBP9/CTLH complex." Thesis, University of Bristol, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.665153.
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Ubiquitination is an essential post-translational modification that regulates signalling and protein turnover in eukaryotic cells. However, many ubiquitin E3 ligases remain poorly understood. The mammalian muskelin/RanBP9/CTLH complex contains eight proteins, five of which, RanBP9 (RanBPM), TWA1, Maea, Rmnd5a and muskelin, share striking similarities of domain organisation. In Saccharomyces cerevisiae, the related GID complex includes the Rmnd5a homologue GID2 which has E3 ubiquitin ligase activity and down-regulates gluconeogenesis. E3 ubiquitin ligase activity of mammalian Rmnd5a has not been reported. To better understand the large mammalian complex a major goal of this thesis was to analyse its evolution as a multi-protein system. Bioinformatic studies identify that TWA1, Rmnd5 and Maea are conserved throughout five eukaryotic supergroups. RanBPM is absent from excavates and from some lineages within other super-groups, and muskelin is present only in opisthokonts. Phylogenetic analysis based on the shared sequence regions that correspond to the lissencephaly-l homology (LisH) and C-terminal to LisH (CTLH) domains revealed closer relationships between Rmnd5 and MAEA, and TWAl and RanBPM, respectively. In-depth sequence analyses confirmed the greater similarity of the LisH/ CTLH domains of Rmnd5 and MAEA vs. TWAl and RanBPM, respectively, and id~ntified unique signatures of conserved residues within the LisH and CTLH domains of each protein. ~ further goal was to purify and express Rmnd5a and TWAl for laboratory experiments. Bacterially expressed Rmnd5a exhibits E3 ubiquitin ligase activity in Escherichia coli BL21lysates but not as a purified protein. Bacterial expression and purification of TWAl enabled biophysical characterisation of TWAl as an all a-helical, natively-dimerised protein. TWAl crystals were produced. When optimized, crystals diffracted to 3.5A, though a 3D structure was not resolved. Threaded structure predictions of Rmnd5a and TWAl agreed with secondary structure prediction algorithms. These studies advance knowledge of structural! functional relationships of proteins in this poorly-understood complex.
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Brewin, J. J. "Generation of calcineurin inhibitor resistant EBV-CTLs for the treatment of post transplant lymphoma." Thesis, University College London (University of London), 2010. http://discovery.ucl.ac.uk/19418/.
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Epstein Barr Virus driven post transplant lymphoproliferative disease (PTLD) is a serious complication following either stem cell or solid organ transplantation (SOT), occurring as a result of suppressed cellular immunity. Adoptive transfer of EBV specific cytotoxic T cells (EBV-CTLs) is effective as both prophylaxis and treatment for PTLD following stem cell transplantation, but is less effective when applied to PTLD after SOT. It is likely that the continued pharmacologic immunosuppression designed to prevent graft rejection compromises the function of infused EBV-CTLs. To address this issue, we have generated calcineurin (CN) mutants that do not bind the immunosuppressants Tacrolimus (FK506) and Cyclosporin A (CsA), therefore conferring resistance to these CN inhibitors. A panel of 54 such mutants was designed, generated and screened in a Luciferase expression assay, with identification of those capable of resisting suppression with FK506, CsA or both. Subsequently, in assays utilising both the Jurkat T cell line and primary human EBV-CTL lines, mutant CNa12 conferred resistance to CsA, mutant CNa22 conferred resistance to FK506 and mutant CNb30 rendered cells resistant to both calcineurin inhibitors. EBV-CTL lines transduced with a retroviral vector encoding these mutants retained the ability to both proliferate and secrete normal levels of interferon-\gamma in the presence of therapeutic and supratherapeutic levels of FK506 (CNa12), CsA (CNa22), or both (CNb30). The cytotoxicity, phenotype and antigen dependence of EBV-CTL lines were unaffected by expression of mutant CN. A xenogenic murine model of PTLD was established in the RAG2^{-/-}/\gamma c^{-/-}/C5^{-/-} triple knockout SCID mouse strain and the ability of EBV-CTL lines to induce tumour regression was examined. Administration of EBV-CTLs caused regression of subcutaneous LCL tumours in vivo in some donors. This model will be utilised in further investigations of transduced EBV-CTLs in vivo. The generation of EBV-CTLs that are resistant to CN inhibitors should allow effective immunotherapy in the SOT setting without risking rejection of the graft by reducing immunosuppression. Additionally this represents a generic approach to improving immunotherapy in the face of immunosuppression in other settings.
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Auchabie, Johann. "Modulation de la triade de costimulation CD28 / CD80-86 / CTLA-4 en transplantation rénale." Nantes, 2015. https://archive.bu.univ-nantes.fr/pollux/show/show?id=d2ab7e3d-d947-48e7-8625-491a0019997d.
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En transplantation rénale, la durée de vie des greffons reste limitée par l'apparition d'une dysfonction chronique secondaire à la néphrotoxicité des CNI, mais aussi à la survenue d'un rejet chronique humoral. La triade CD28 / CD80-86 / CTLA-4, principale voie de costimulation, constitue une cible privilégiée. L'antagonisation de CD80-86, le ligand commun de CD28 et CTLA-4 par le Belatacept (CTLA4-Ig) a démontré améliorer la fonction du greffon tout en limitant l'apparition d'allo-anticorps, mais elle est associée à une augmentation du taux de rejet aigu faisant suspecter un effet délétère du blocage de CTLA-4. Préserver cette voie est le principal atout du FR104, un anti-CD28 Fab' pegylé, développé par notre équipe et ayant fait la preuve de son efficacité préclinique en transplantation rénale chez le primate. L'objectif de cette thèse était, après avoir évalué le FR104 en association avec d'autres immunosuppresseurs, de le comparer directement avec le Belatacept dans un protocole d'immunosuppression sous-optimal, dans lequel 80% des animaux sous Belatacept ont présenté des rejets cortico-résistants contrairement à ceux sous FR104 (40% de rejet, tous cortico-sensibles, avec une fonction rénale stable pendant 1 an). Cette supériorité pouvait être rapportée aux fonctions extrinsèques du CTLA-4 principalement dues aux Tregs, mais aussi aux signaux inhibiteurs directement médiés par CTLA-4. En effet la plus forte expression d'IL-21 dans les biopsies protocolaires des animaux sous CTLA4-Ig faisait suspecter un meilleur contrôle des Tfh (principale source d'IL-21), par le FR104, ce qu'ont confirmé des données in vitro chez l'homme et in vivo dans un modèle murinKidney graft half-life remain limited by the development of a chronic dysfunction due to CNI nephrotoxicity, but also to the occurrence of a chronic antibody mediated rejection. The major costimulation pathway CD28 / CD80-86 / CTLA-4 triad, represent a new privileged target. Antagonizing CD80-86, the common ligand of CD28 and CTLA-4 with Belatacept (CTLA4-Ig) demonstrated an improvement of renal function associated with a low occurrence of allo-antibody. However Belatacept is associated with an increased risk of acute rejection, suggesting that CTLA-4 blockade could be deleterious. Preserving this pathway, is the main advantage of FR104, an anti-CD28 Fab' antibody pegylated, developed in our team, which proved preclinical efficacy in a model of allotransplantation in primate. The goal of this thesis was, after evaluating FR104 in association with major immunosuppressive drugs, to compare it in head to head with Belatacept in a protocol of suboptimal immunosuppression. In Belatacept group 80% of the animals presented steroid resistant rejection as opposed to animals under FR104 (40% of rejection ever steroid sensitive, followed by a stable renal function during one year). This superiority might be explain by CTLA-4 extrinsic function mainly due to Treg, but also by CTLA-4 intrinsic inhibitory signaling. Indeed IL-21 gene expression was stronger in protocol biopsies of CTLA4-Ig treated animals suggesting that follicular helper T cells, his main source, were better controlled by FR104, as supported by in vitro experiment and data in vivo in mice