Teses / dissertações: "Glycogénose de type III"

1

Vidal, Patrice. "Développement d'un traitement de thérapie génique pour la glycogénose de type III". Electronic Thesis or Diss., Sorbonne université, 2018. http://www.theses.fr/2018SORUS571.

Texto completo da fonte

Resumo:

La glycogénose de type III (GSDIII) est une maladie génétique récessive due à des mutations affectant l’activité de l'enzyme de débranchement du glycogène (GDE). Les symptômes sont une hépatomégalie et une hypoglycémie chez l’enfant puis une faiblesse musculaire dégénérative chez l’adulte. Aucun traitement curatif n'existe pour GSDIII. Nous avons dans un premier temps développé un modèle de souris GSDIII viable possédant phénotype proche de la maladie de l’homme. La thérapie génique permet le traitement des maladies métaboliques et neuromusculaires. En thérapie génique in vivo, les vecteurs dérivés du virus adéno-associé (AAV) ont démontré leur efficacité chez l’homme. Une limitation dans le développement d'une thérapie génique pour la GSDIII est la taille du transgène qui dépasse la taille d’encapsidation de l'AAV. Nous avons exploré une approche alternative utilisant la voie lysosomale de la dégradation du glycogène par l’enzyme GAA. Les résultats chez les souris GSDIII montrent que l’augmentation de la quantité de GAA dans les muscles ne permet pas de traiter le phénotype de la GSDIII alors qu’au contraire elle induit une normalisation de la quantité du glycogène hépatique. La seconde étape fut de faire exprimer à nouveau la GDE par les cellules. Nous avons développé deux vecteurs pouvant utiliser les mécanismes de la recombinaison homologue. Cette stratégie a permis la correction du phénotype GSDIII dans le modèle murin de la maladie. Les résultats montrent qu’il est possible de corriger la faiblesse musculaire ainsi que l’accumulation de glycogène conduisant à la vacuolisation du tissu. L’efficacité de cette stratégie ne reste néanmoins que partielle dans le foie
Glycogen storage disease type III (GSDIII) is a recessive genetic disorder caused by mutations affecting the activity of the glycogen debranching enzyme (GDE). Symptoms are hepatomegaly and hypoglycemia during childhood and degenerative muscle weakness during adulthood. At present, no curative treatment exists for GSDIII. First, we developed and characterized a mouse model that faithfully recapitulates the human disease. Gene therapy allows the treatment of previously untreatable metabolic and neuromuscular diseases. Adeno-associated virus (AAV) vectors are vectors of choice for in vivo gene therapy, with an excellent safety and efficacy profile demonstrated in human. A major limitation for GSDIII is the size of the transgene that exceeds the genome packaging capacity of AAV vectors. We explored an alternative approach using the lysosomal pathway and the acid alpha-glucosidase (GAA) able to degrade the glycogen, overloading the lysosomes with this protein. In muscles, the increase of GAA activity is not able to treat the phenotype of GSDIII whereas the overexpression of GAA in the liver induces a normalization of the concentration of glycogen. The second step of this thesis was to have GDE de novo expressed in cells. We developed strategy based on the injection of two vectors that can use the mechanisms of homologous recombination. This allowed the correction of the GSDIII phenotype in a murine model of the disease. The results show that it is possible to correct the muscle phenotype of GSDIII. Nevertheless, the effectiveness of this strategy remains only partial in the liver, again highlighting a different glycogen degradation pathway in both tissues

Estilos ABNT, Harvard, Vancouver, APA, etc.

2

Rossiaud, Lucille. "Modélisation et compréhension de la glycogénose de type III grâce à l'utilisation de cellules souches pluripotentes induites humaines". Electronic Thesis or Diss., université Paris-Saclay, 2024. https://www.biblio.univ-evry.fr/theses/2024/interne/2024UPASL091.pdf.

Texto completo da fonte

Resumo:

La glycogénose de type III (GSDIII) est une maladie génétique rare due à un déficit en enzyme débranchante du glycogène (GDE), provoquant une accumulation de glycogène dans le foie, le cœur et les muscles squelettiques. Alors que les atteintes hépatiques dominent durant l'enfance, les atteintes musculaires progressent et deviennent prédominantes à l'âge adulte. L'absence de modèles humains freine la compréhension de cette pathologie et la mise au point de traitements.Dans ce contexte, mon premier objectif était de créer des modèles pathologiques humains in vitro à partir de cellules souches pluripotentes induites (hiPSC). J'ai généré cinq lignées hiPSC pathologiques : quatre lignées dérivées de patients par reprogrammation et une lignée génétiquement modifiée par CRISPR/Cas9. Ces cellules ont ensuite été différenciées en myocytes et en hépatocytes, les deux types cellulaires pertinents pour l'étude de la GSDIII. J'ai confirmé que ces cellules expriment respectivement les marqueurs spécifiques des muscles et du foie, et récapitulent, en condition de privation de glucose, le phénotype d'accumulation de glycogène en comparaison à des cellules saines.Le deuxième objectif visait à mieux comprendre les mécanismes physiopathologiques de la GSDIII et à identifier de nouveaux biomarqueurs de la pathologie. Je me suis d'abord focalisée sur le muscle, pour lequel j'ai identifié, par séquençage ARN des myocytes dérivés d'hiPSC, des gènes différentiellement exprimés entre cellules saines et pathologiques. Une analyse comparative avec les données d'un séquençage ARN réalisés sur des biopsies de triceps de souris saines et GSDIII a révélé la surexpression d'un gène commun codant pour la Galectine-3, un marqueur de vésicules endommagées. Sa surexpression a été validée dans les myocytes mutés dérivés d'hiPSC, ainsi que dans les triceps de souris GSDIII et dans des biopsies de patients. En parallèle, une approche similaire sur les hépatocytes dérivés d'hiPSC a permis d'identifier de potentiels biomarqueurs du foie, ouvrant la voie à une meilleure compréhension des mécanismes physiopathologiques hépatiques. Le dernier objectif était d'utiliser ces modèles pathologiques humains in vitro pour tester de nouvelles thérapies. J'ai démontré que le traitement de myocytes mutés par des vecteurs AAV exprimant la GDE humaine complète ou tronquée, préalablement validés dans des modèles in vivo de souris et de rats GSDIII, diminuait l'accumulation de glycogène à des niveaux comparables à ceux de cellules saines. Ces expériences ont confirmé l'intérêt du développement de ces nouveaux modèles in vitro. L'ensemble de ces travaux ont permis l'identification de nouveaux biomarqueurs de la GSDIII, permettant d'améliorer la compréhension des mécanismes moléculaires dans le muscle et le foie. La création de ces nouveaux modèles in vitro ouvre également de nouvelles perspectives thérapeutiques pour la GSDIII, notamment en facilitant le criblage de médicaments
Glycogen storage disease type III (GSDIII) is a rare genetic disorder caused by glycogen debranching enzyme (GDE) deficiency, leading to an accumulation of glycogen accumulation in the liver, heart and skeletal muscles. While liver damages predominate in childhood, muscle impairments progress and become predominant in adulthood. The lack of human models hinders our understanding of the disease and the development of treatments.In this context, my first objective was to create in vitro human pathological models from induced pluripotent stem cells (hiPSCs). I generated five pathological hiPSC lines: four lines derived from patients by reprogramming and one line genetically modified by CRISPR/Cas9. These cells were then differentiated into myocytes and hepatocytes, the two relevant cell types for the study of GSDIII. I confirmed that these cells express muscle and liver specific markers respectively, and recapitulate the glycogen accumulation phenotype under glucose starvation conditions compared to healthy cells.The second objective was to better understand the pathophysiological mechanisms of GSDIII and to identify new biomarkers of the disease. I first focused on muscle, for which I identified genes differentially expressed between healthy and pathological cells by RNA sequencing of hiPSC-derived myocytes. Comparative analysis with RNA sequencing data from triceps biopsies of healthy and GSDIII mice revealed overexpression of a common gene encoding galectin-3, a marker of damaged vesicles. This overexpression was validated in mutated myocytes derived from hiPSCs, as well as in the triceps of GSDIII mice and in patient biopsies. In parallel, a similar approach on hiPSC-derived hepatocytes identified potential liver biomarkers, paving the way for a better understanding of the mechanisms of liver damage.The final objective was to use these in vitro human pathological models to test new therapies. I demonstrated that treatment of mutated myocytes with AAV vectors expressing complete or truncated human GDE, previously validated on in vivo GSDIII mouse and rat models, reduced glycogen accumulation to levels comparable to those of healthy cells. These experiments confirmed the value of developing these new in vitro models.Taken together, this work has led to the identification of new biomarkers for GSDIII, providing a better understanding of the molecular mechanisms in muscle and liver. The creation of these new in vitro models also opens up new therapeutic prospects for GSDIII, particularly by facilitating drug screening

Estilos ABNT, Harvard, Vancouver, APA, etc.

3

Douillard-Guilloux, Gaëlle. "Nouvelles approches thérapeutiques dans la glycogénose de type 2". Paris 7, 2008. http://www.theses.fr/2008PA077119.

Texto completo da fonte

Resumo:

La glycogénose de type II est une maladie liée au déficit en alpha-glucosidase acide. Elle est caractérisée par une accumulation intra-lysosomale de glycogène dans le muscle squelettique, Notre travail a été de développer de nouvelles approches thérapeutiques pour cette pathologie. Nous avons tout d'abord tenté de moduler la synthèse du glycogène (thérapie par inhibtion de substrat) en inhibant les enzymes clés de sa biosynthèse : la glycogénine (GYG) et la glycogène synthase (GYS), à l'aide de shRNA. Un vecteur viral AAV contenant le shARN-GYS2 a été construit et injecté par voie intramusculaire chez des souris GAA-/- et a permis de réduire l'accumulation du glycogène. Afin de confirmer, une approche par knock-out a été développée. Les souris GAA-/- ont été croisées avec des souris mutées pour la GYS musculaire. Ces souris double KO ne présentent pas d'accumulation de glycogène et leur capacité a exercer une activité musculaire est nettement améliorée par rapport aux souris GAA-/-. Par ailleurs, nous avons également testé la possibilité de développer une immunotolérance vis à vis de l'enzyme recombinante par induction d'un chimérisme après greffe de cellules souches hématopoïétiques (CSH). Nous avons montré le développement d'une tolérance à l'enzymothérapie avec absence totale de production d'anticorps anti-GAA chez les souris ayant reçu les CSH-GAA. En parallèle, afin d'essayer de contre-balancer la production massive d'anticorps anti-GAA, une augmentation de l'expression et de la sécrétion de la GAA a été obtenue sur les cellules musculaires de patients transduites par un vecteur lentiviral contenant le gène de la GAA sous le contrôle d'un promoteur muscle-spécifique fort
Glycogen storage disease type II is caused by defects in the lysosomal acid alpha-glucosidase (GAA) gene. This pathology is characterized by glycogen accumulation, especially in muscles. Enzyme Replacement Therapy efficiency is restricted. Therefore, our aim is to develop a novel therapeutical approach for this pathology. Small interfering RNAs (siRNAs) targeted to the two major genes for glycogen synthesis (glycogenin and glycogen synthase) were designed to explore the possibility of silencing these two genes. A viral vector AAV with the shARN-GYS2 was injected in the muscle of GAA-/- mice and reduced the glycogen accumulation. In the same time, an approach by knock-out was developped. Mice GAA-/- were crossed with mice KO for the muscular form of GYS. These double KO mice do not present accumulation of glycogen and their muscular activity is clearly improved compared to GAA-/- mice. We also tested the possibility to induce a immunotolerance against the recombinante enzyme by using bone marrow transplantation. The development of tolerance to the recombinante enzyme induce no more production of anti-GAA antibody in the mice having received the CSH-GAA. In parallel, to decrease the massive destruction of the recombinante enzyme by the anti-GAA antibody, An over-expression of the GAA was obtained on the muscular cells of patients transduites by a vector lentiviral containing gene of the GAA under the control of a strong muscle-specific promotor

Estilos ABNT, Harvard, Vancouver, APA, etc.

4

Hordeaux, Juliette. "Thérapie génique des manifestations neurologiques de la maladie de Pompe (glycogénose de type II)". Nantes, 2014. http://www.theses.fr/2014NANT2098.

Texto completo da fonte

Resumo:

La maladie de Pompe ou glycogénose de type II est une maladie de surcharge Iysosomiale causée par la mutation de l'enzyme alpha-glucosidase acide (GAA) à l'origine d'une accumulation de glycogène dans le coeur, les muscles et le système nerveux central (SNC). La forme infantile classique est caractérisée par une hypotonie et une cardiomyopathie fatale. La correction du coeur par enzymothérapie a permis d'allonger l'espérance de vie des patients révélant une nouvelle histoire naturelle. Le phénotype neurologique émergent et la correction partielle des muscles pourraient être liés à la surcharge du SNC. Nous postulons que la restauration de l'activité GAA dans le SNC par thérapie génique intrathécale permettrait i) de corriger les manifestations neurologiques de la maladie et ii) d'apporter un bénéfice sur la fonction neuromusculaire. Nous avons dans un premier temps démontré la transduction efficace du SNC après administration intrathécale d'un virus adéno-associé (AA V) recombinant codant un gène rapporteur. Nous avons ensuite administré un vecteur thérapeutique AA V -gaa par voie intrathécale chez des souris GAA-KO 6neo âgées de 1 mois puis nous avons suivi leur fonction neuromusculaire pendant un an. Nous démontrons une normalisation de Ia fonction neurologique corrélée à la correction enzymatique, biochimique et histologique du SNC. La force des souris est restaurée partiellement en l'absence de correction de la pathologie musculaire. Nos résultats suggèrent l'implication du SNC dans la physiopathologie de l'atteinte musculaire. Ces travaux ouvrent des perspectives de stratégies thérapeutiques combinées des organes périphériques et du SNC chez l'homme
Pompe disease (glycogen storage disease type II) is a lysosomal storage disorder caused by acid-oe-glucosidase (GAA) deficiency leading to progressive accumulation of glycogen in the heart, muscles, and central nervous system (CNS). The disease manifests as a fatal cardiomyopathy in infantile form. Cardiac correction by enzyme replacement therapy (ERT) has recently prolonged the lifespan of these patients, revealing a new natural history. The emergent neurologie phenotype and the persistence of muscular weakness in survivors are currently partly attributed to CNS glycogen storage, uncorrected by ERT. We hypothesized that CNS correction by gene therapy using recombinant Adena-associated viruses (rAA V) encoding the GAA transgene would alleviate the neurologie manifestations of the disease and would lead to an improvement of the neuromuscular function. To address this question, we first demonstrated using a reporter gene that the injection of rAA V in the cerebrospinal fluid (intrathecal injection) enables efficient and diffuse transduction of the CNS. GAA-KO 6neo mice were next treated with intrathecal AA V-gaa at one month and their neuromuscular function was assessed for one year. We demonstrate a significant functional neurologie correction in treated animals and a partial restoration of the muscular strength. The entire CNS shows enzymatic, biochemical and histological correction. Muscle glycogen storage is not cleared by the treatment, thus suggesting that the partial restoration of strength is directly related to the CNS correction. This widespread CNS cure and its impact on the global neuromuscular function offer new perspectives for the management of patients

Estilos ABNT, Harvard, Vancouver, APA, etc.

5

Clar, Julie. "Nouvelles stratégies d’étude et de prévention des complications hépatorénales de la glycogénose de type Ia". Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10163.

Texto completo da fonte

Resumo:

La glycogénose de type Ia (GSDIa) est une maladie métabolique rare causée par un déficit en glucose-6- phosphatase (G6Pase), menant à l'absence de production endogène de glucose. Cette pathologie est caractérisée par des hypoglycémies sévères, une hépatomégalie et une stéatose hépatique ainsi qu'une néphromégalie. En absence de traitement curatif, la prise en charge de cette maladie repose actuellement sur des mesures diététiques très strictes. Cependant, des complications apparaissent avec l'âge comme le développement de tumeurs hépatiques et la progression de la néphropathie vers l'insuffisance rénale. Afin d'étudier l'évolution de cette pathologie à long terme, nous avons utilisé des modèles murins originaux présentant une invalidation du gène de la sous-unité catalytique de la G6Pase spécifiquement au niveau du foie ou des reins. Dans ce travail, nous avons démontré que la déficience en G6Pase uniquement au niveau des reins est suffisante pour entrainer le développement de la pathologie rénale de la GSDIa. Les souris déficientes en G6Pase hépatique nous ont permis de mettre en évidence les effets délétères d'une consommation modérée de fructose ou de galactose et d'une alimentation riche en lipides, de type « cafétéria », sur la pathologie hépatique de la GSDIa, en particulier sur le développement tumoral. Nous avons également démontré chez ces souris l'efficacité et l'innocuité d'un traitement par thérapie génique ciblant le foie. Le transfert de gène avec un vecteur lentiviral, permettant l'intégration du transgène au génome, semble plus efficace qu'avec un vecteur AAV pour prévenir le développement de la pathologie hépatique de la GSDIa et l'apparition des tumeurs
Glycogen storage disease type Ia (GSDIa) is a rare metabolic disease caused by glucose-6-phosphatase (G6Pase) deficiency, leading to the absence of endogenous glucose production. This pathology is characterized by severe hypoglycemia, hepatomegaly, hepatic steatosis and nephromegaly. In the absence of a curative therapy, the current treatments available consist in strict dietary management. However, various complications occur with aging, such as hepatic tumor development and progressive chronic renal disease leading to renal failure. In order to study the long term pathology development, we used original mouse models, presenting an invalidation of the gene encoding the G6Pase catalytic subunit, specifically in the liver or in the kidneys. In this work, we demonstrated that renal G6Pase deficiency alone is sufficient to induce the development of the GSDIa nephropathy. Mice with liver-specific G6Pase deficiency allowed us to highlight the deleterious effects of high-fat diet, such as « fast-food » diet, as well as moderate consumption of fructose or galactose on the hepatic GSDIa pathology, particularly on tumor development. Furthermore, we demonstrated the efficiency and innocuity of gene therapies targeting the liver in these mice. Gene transfer with a lentiviral vector, allowing transgene integration into the genome, seems to be more efficient than an AAV vector in preventing the development of hepatic GSDIa pathology and tumor formation

Estilos ABNT, Harvard, Vancouver, APA, etc.

6

Nicolino, Marc. "Glycogénose Type II (Maladie de Pompe) : approche d'une thérapie génique et caractérisation des anomalies moléculaires". Paris 5, 1999. http://www.theses.fr/1999PA05CD17.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

7

Mutel, Élodie. "Caractérisation d'un nouveau modèle murin de glycogénose de type 1a : du métabolisme glucidique à la thérapie génique". Phd thesis, Université Claude Bernard - Lyon I, 2011. http://tel.archives-ouvertes.fr/tel-00858006.

Texto completo da fonte

Resumo:

La glycogénose de type 1a (GSD1a) est une maladie métabolique rare liée à une absence d'activité glucose‐6 phosphatase (G6Pase). La G6Pase est une enzyme clé de la production endogène de glucose (PEG) catalysant l'hydrolyse du G6P en glucose avant sa libération dans le sang. Cette fonction est restreinte au foie, aux reins et à l'intestin. La GSD1a est caractérisée par des hypoglycémies chroniques, une hépatomégalie associée à une stéatose hépatique et une néphromégalie. A plus longterme, la plupart des patients développent des adénomes. Un modèle murin de GSD 1a existe mais les souris ne survivent pas après le sevrage. Nous avons donc généré un modèle original de GSD1a, en invalidant le gène de la sous‐unité catalytique de la G6Pase spécifiquement dans le foie, grâce à une stratégie CRE‐LOX inductible (souris L‐G6pc‐/‐). Dans ce travail, nous avons montré que les souris L‐G6pc‐/‐ sont viables et reproduisent parfaitement la pathologie hépatique de la GSD1a, y compris le développement d'adénomes hépatiques après 9 mois d'invalidation. La viabilité des souris nous a permis de débuter des traitements par thérapie génique ciblant le foie à l'aide de vecteurs lentiviraux et AAV. La survie de ces souris, qui ne peuvent pas produire du glucose par le foie, repose la question du rôle relatif de la production hépatique de glucose dans la régulation de la glycémie Nous avons montré que les souris L‐G6pc‐/‐ sont capables de réguler leur glycémie, même au cours d'un jeûne prolongé. Ce maintien de l'homéostasie glucidique est due à une induction rapide de la néoglucogenèse rénale et intestinale, principalement par un mécanisme dépendant du glucagon

Estilos ABNT, Harvard, Vancouver, APA, etc.

8

Mutel, Élodie. "Caractérisation d’un nouveau modèle murin de glycogénose de type 1a : du métabolisme glucidique à la thérapie génique". Thesis, Lyon 1, 2011. http://www.theses.fr/2011LYO10005/document.

Texto completo da fonte

Resumo:

La glycogénose de type 1a (GSD1a) est une maladie métabolique rare liée à une absence d’activité glucose‐6 phosphatase (G6Pase). La G6Pase est une enzyme clé de la production endogène de glucose (PEG) catalysant l’hydrolyse du G6P en glucose avant sa libération dans le sang. Cette fonction est restreinte au foie, aux reins et à l’intestin. La GSD1a est caractérisée par des hypoglycémies chroniques, une hépatomégalie associée à une stéatose hépatique et une néphromégalie. A plus longterme, la plupart des patients développent des adénomes. Un modèle murin de GSD 1a existe mais les souris ne survivent pas après le sevrage. Nous avons donc généré un modèle original de GSD1a, en invalidant le gène de la sous‐unité catalytique de la G6Pase spécifiquement dans le foie, grâce à une stratégie CRE‐LOX inductible (souris L‐G6pc‐/‐). Dans ce travail, nous avons montré que les souris L‐G6pc‐/‐ sont viables et reproduisent parfaitement la pathologie hépatique de la GSD1a, y compris le développement d’adénomes hépatiques après 9 mois d’invalidation. La viabilité des souris nous a permis de débuter des traitements par thérapie génique ciblant le foie à l’aide de vecteurs lentiviraux et AAV. La survie de ces souris, qui ne peuvent pas produire du glucose par le foie, repose la question du rôle relatif de la production hépatique de glucose dans la régulation de la glycémie Nous avons montré que les souris L‐G6pc‐/‐ sont capables de réguler leur glycémie, même au cours d’un jeûne prolongé. Ce maintien de l’homéostasie glucidique est due à une induction rapide de la néoglucogenèse rénale et intestinale, principalement par un mécanisme dépendant du glucagon
Glycogen storage disease type 1a (GSD1a) is a rare metabolic disorder due to an absence of glucose‐6 phosphatase (G6Pase) activity. G6Pase is the key enzyme of endogenous glucose production (EGP) and catalyzes the last step before the glucose release into the bloodstream. This function to produce glucose is restricted to the liver, the kidneys and the intestine. GSD1a is characterized by chronic hypoglycemia, hepatomegaly associated with hepatic steatosis and nephromegaly. The longterm complications of G6Pase deficiency include hepatocellular adenomas. The available animal model of GSD1a rarely survive over three months of age and the study of mechanisms of hepatocellular adenomas development cannot be investigated. So, we generated an original mouse model of GSD1a with a liver‐specific invalidation of catalytic subunit of G6Pase gene by an inducible CRE‐LOX strategy (L‐G6pc‐/‐ mice). In this work, we demonstrated that L‐G6pc‐/‐ were viable and totally reproduced the liver pathology of GSD1a, including the late development of hepatocellular adenomas. Then, we have begun liver gene therapy treatment using lentiviral and AAV vectors to correct the hepatic pathology. Finally, concerning glucose homeostasis, we have demonstrated that L‐G6pc‐/‐ were able to regulate blood glucose, during prolonged fast, even in the absence of hepatic glucose production. Rapidly, L‐G6pc‐/‐ mice were able to induce renal and intestinal gluconeogenesis thanks to a key role of glucagon and the development of a metabolic acidosis. These results provide evidence that the major role of the liver for EGP during fasting requires re‐examination

Estilos ABNT, Harvard, Vancouver, APA, etc.

9

Monteillet, Laure. "La maladie chronique rénale de la glycogénose de type I, des mécanismes moléculaires aux nouvelles stratégies thérapeutiques". Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1140.

Texto completo da fonte

Resumo:

La glycogénose de type Ia (GSDIa) est une maladie métabolique rare causée par une déficience en glucose-6-phosphatase (G6Pase), due à des mutations de la sous-unité catalytique (G6PC). Cette enzyme confère au foie, aux reins et à l’intestin la capacité de produire du glucose. Les patients atteints de GSDIa sont donc incapables de produire du glucose et souffrent d’hypoglycémies sévères lors de jeûnes courts. De plus, la déficience en G6Pase provoque une accumulation de glucose-6 phosphate dans le foie et les reins, conduisant à l’accumulation de glycogène et de lipides. A long terme, la plupart des patients souffre d’une maladie chronique rénale (MCR), qui peut évoluer en insuffisance rénale, nécessitant une mise sous dialyse ou une transplantation rénale. Cette MCR se caractérise par une fibrose, ainsi que par le développement de kystes dans les stades tardifs. Au niveau du foie, les patients développent une hépatomégalie et une stéatose hépatique qui peut évoluer vers le développement d’adénomes ou carcinomes hépatocellulaires. Le but de mes travaux de thèse a été d’identifier les mécanismes moléculaires impliqués dans l’établissement de la pathologie rénale et la formation des kystes, à l’aide de modèles murins invalidés pour le gène G6pc spécifiquement dans les reins (souris K.G6pc-/-). Alors que la GSDIa est une maladie caractérisée par l’accumulation hépatique et rénale de glycogène, nous avons d’abord montré que le développement de la fibrose, à l’origine de la perte de la fonction rénale, était induit par l’accumulation de lipides, indépendamment du contenu en glycogène. De plus, l’utilisation d’un agoniste de PPARα, le fénofibrate, en diminuant le contenu lipidique rénal, a ralenti l’installation de la fibrose et l’évolution de la MCR. Le mécanisme moléculaire impliqué est l’activation du système rénine angiotensine par les dérivés lipidiques, qui induit l’expression du facteur profibrotique TGFβ1. De même, le fénofibrate en limitant l’accumulation de lipides hépatiques a prévenu le développement d’atteintes hépatiques caractéristiques de la GSDI. Ainsi, l’activation du catabolisme des lipides par des agonistes de PPARα semble une stratégie thérapeutique intéressante pour réduire la progression des maladies rénales et hépatique de la GSDI. La deuxième partie de mes résultats suggèrent que le développement de kystes rénaux chez les patients atteints de la GSDI pourrait être causé par une altération du cil primaire, organelle jouant un rôle clé dans le maintien d’une structure et fonction normale des reins. En effet, une augmentation de la longueur du cil primaire a pu être observée dans les reins des souris K.G6pc-/- associée à une dérégulation de différentes protéines impliquées dans sa structure et sa fonction, par rapport aux souris contrôles. Nous avons également mis en évidence une reprogrammation métabolique de type Warburg, caractérisée par une activation accrue de la glycolyse aérobie, une inhibition de l’oxydation mitochondriale du pyruvate et une production de lipides. Ainsi, l’ensemble de ces perturbations va favoriser la prolifération cellulaire et le développement de kystes, et pourrait mener au développement de tumeur rénale comme observée chez une souris K.G6pc-/-. En conclusion nous avons démontré que, dans le cadre de la GSDI, l’accumulation de lipides dans les reins et le foie, secondaire à la déficience en G6Pase, joue un rôle clé dans le développement des complications hépatiques et rénales à long terme. Également, la reprogrammation métabolique rénale de type Warburg, prenant place dans le cadre de la GSDI, associée à un défaut du cil primaire pourrait être à l’origine de la formation des kystes et de tumeurs rénales. Ces études, en permettant une meilleure compréhension de la physiopathologie des complications à long terme de la GSDIa, offrent de nouvelles perspectives concernant les stratégies thérapeutiques à développer pour une meilleure prise en charge des patients atteints de GSDIa
Glycogen storage disease type Ia (GSDIa) is a rare metabolic disease caused by glucose-6-phosphatase (G6Pase) deficiency, due to mutations on the gene encoding G6Pase catalytic subunit (G6PC). This enzyme confers to the liver, kidneys and intestine the ability to produce glucose. Thus, patients with GSDIa are unable to ensure endogenous glucose production and suffer from severe hypoglycemia during fasting in the absence of nutritional control. In addition, G6Pase deficiency causes intracellular accumulation of glucose-6 phosphate in the liver and kidneys, leading to metabolic defects and the accumulation of glycogen and lipids. Over time, most adult patients suffer from chronic kidney disease (CKD), which can progress to kidney failure, requiring dialysis or kidney transplantation. This nephropathy is characterized in particular by tubulo-interstitial fibrosis and glomerulosclerosis, as well as by the development of cysts in the late stages. Moreover, patients develop hepatomegaly and hepatic steatosis that may progress to the development of hepatocellular adenomas or carcinomas. The aim of my thesis was to identify the molecular mechanisms involved in the establishment of renal pathology and cyst formation in GSDIa, by using mouse models where G6pc gene is specifically deleted in the kidneys (K.G6pc-/- mice). While GSDIa is a disease characterized by glycogen accumulation in the liver and kidneys, we first showed that the development of fibrosis, which causes progressive loss of kidney function, was induced by intracellular accumulation of lipids, regardless of glycogen content. The molecular mechanism probably involved is the activation of the renin angiotensin system by lipid derivatives such as diacylglycerol, which induced the expression of the profibrotic factor TGFβ1 and an epithelial-mesenchymal transition. In addition, the use of a PPARα agonist, i.e. fenofibrate, by decreasing renal lipid content, reduced the development of fibrosis and CKD evolution. Similarly, fenofibrate treatment prevented the accumulation of lipids in the liver and the development of liver damages that cause tumor development. Thus, the activation of lipid catabolism by PPARα agonists such as fenofibrate seems to be an interesting therapeutic strategy to reduce the progression of renal and hepatic diseases of GSDIa. The second part of my results suggest that the development of renal cysts in GSDI patients may be caused by an alteration of the primary cilia, a non-motile organelle that plays a key role in maintaining normal kidney structure and function. Indeed, defects in the primary cilia are involved in many polycystic kidney diseases. In summary, an increase in the length of the primary cilia was observed in the kidneys of K.G6pc-/- mice, which could be explained by a deregulation of the expression of different proteins involved in cilia structure and function, compared to control mice. We also demonstrated a metabolic reprogramming leading to a Warburg metabolism, characterized by the increased activation of aerobic glycolysis and the inhibition of mitochondrial pyruvate oxidation and lipid production in K.G6pc-/- mice. Thus, all these disorders would promote cell proliferation and cyst development, and could lead to the development of renal tumor, as recently observed in one K.G6pc-/- mouse (out of 36 studied mice). In conclusion, we have shown that, in GSDI, the accumulation of lipids in the kidneys and liver that occurs secondary to G6Pase deficiency plays a key role in the development of hepatic and renal long-term complications. In addition, the Warburg like metabolic reprogramming taking place in the GSDIa kidneys, associated with a defect in the primary cilia, could be at the origin of cysts formation and renal tumors. These new studies, by providing a better understanding of the pathophysiology of long-term complications of GSDIa, offer new perspectives on therapeutic strategies to be developed for better management of patients

Estilos ABNT, Harvard, Vancouver, APA, etc.

10

Shelly, Claire. "Type III subfactors and planar algebras". Thesis, Cardiff University, 2012. http://orca.cf.ac.uk/44565/.

Texto completo da fonte

Resumo:

In this thesis we investigate the theory of planar algebras for type III subfactors. We show directly how to associate a planar algebra to a type III subfactor using endomorphisms and intertwiners. We begin by describing how to define a type III version of the Temperley-Lieb planar algebra before giving a general definition of a type III planar algebra. We define a presenting map using endomorphisms and intertwiners and prove that this defines a type III subfactor planar algebra. We show that the definition of a type III subfactor planar algebra may be extended by removing the sphericality condition. We also investigate the reverse implication, and show that if we start with a type III subfactor planar algebra we can produce a type III subfactor using techniques from Guionnet-Jones-Shlyakhtenko and free probability. In the final chapter we investigate the type III version of A2 planar algebras. We extend the results of Chapter 3 to the A2 setting, defining a type III string algebra for SU(3) ADE graphs and relating this to planar algebras. We also discuss further work here relating to A2 planar algebras.

Estilos ABNT, Harvard, Vancouver, APA, etc.

11

Bagaud, Catherine. "Aspect physiopathologique et clinique de la glycogénose 1 bis et intérêt du facteur de croissance dans son traitement à propos d'un cas". Bordeaux 2, 1994. http://www.theses.fr/1994BOR2M206.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

12

Pichon, Julien. "Impact de la surexpression de FoxO3a sur la physiopathologie musculaire de la maladie de Pompe (Glycogénose de type II)". Thesis, Nantes, 2020. http://archive.bu.univ-nantes.fr/pollux/show.action?id=36cea62a-e454-42c5-a21c-1fd5b915de61.

Texto completo da fonte

Resumo:

La maladie de Pompe est une maladie de surcharge lysosomiale due à une mutation de l'alphaglucosidase acide (GAA) conduisant notamment à une atteinte musculaire sévère. Aucun traitement ne permet de corriger efficacement et durablement le muscle squelettique. Une meilleure compréhension des mécanismes pathogéniques impliqués permettrait de proposer des stratégies thérapeutiques plus adaptées. Les travaux présentés ici ont pour objectifs i) de caractériser la physiopathologie musculaire de la maladie de Pompe grâce au modèle murin Gaa"' et ii) d'évaluer l'effet de la surexpression de Fox03a sur l'atteinte musculaire après transfert du gène à l'aide d'un vecteur adénovirus associé (AA V). Les souris Gaa" non traitées présentent une surcharge lysosomiale en glycogène et en agrégats autophagiques, à l'origine d'une vacuolisation sévère des fibres. Cette vacuolisation, bien qu'associée à une atrophie et à du splitting n'entraîne pas de dégénérescence des fibres musculaires. Les cellules satellites, qui sont responsables de la régénération musculaire, restent fonctionnelles mais présentent cependant un défaut d'activation. Chez les souris traitées, la surexpression de Fox03a diminue la surcharge en glycogène et en agrégats autophagiques. Elle augmente aussi le nombre de fibres de grande taille et à noyaux centralisés. Une amélioration de l'atteinte fonctionnelle neuromusculaire est également observée. Ces résultats apportent de nouveaux éléments de compréhension de la physiopathologie musculaire et montrent un caractère bénéfique de la surexpression de Fox03a sur l'atteinte musculaire dans la maladie de Pompe
Pompe disease is a lysosomal storage disease due to deficit in acid alpha-glucosidase (GAA) that mainly induces severe skeletal muscle impairment. There is currently no treatment able to correct the skeletal muscle impairment at long term. A better understanding of the physiopathological mechanisms implicated is essential for the development of new therapeutic strategies. The aims of the present work are i) to characterize skeletal muscle physiopathology of Pompe disease using the Gaa·1- murine model and ii) to evaluate the impact of Fox03a overexpression on muscle physiopathology by gene transfer of AA VFox03a. Gaa" mice exhibit a strong glycogen overload and a progressive autophagie flux disruption, leading to a vacuolization of muscle fibers. Even it is associated with atrophy and fiber splitting, this vacuolization does not lead to muscle fiber degeneration. Satellite cells, which are responsible of fiber regeneration, remain functional but however display a defect of activation. In Gaa·1- mice receiving AA V-Fox03a, we demonstrated that Fox03a overexpression could improve the skeletal muscle impairments, through the prevention of glycogen overload, autophagie build-up and tissue remodeling. Moreover, neuromuscular function is improved by overexpression of Fox03a. Altogether, our findings provide new insight into the skeletal muscle pathophysiology. We positioned Fox03a as ªprotective key element against the development or' skeletal muscle impairment in Pompe disease

Estilos ABNT, Harvard, Vancouver, APA, etc.

13

Louw, Cassandra Alexandrovna. "Characterisation of Trypanosomal Type III and Type IV Hsp40 proteins". Thesis, Rhodes University, 2009. http://hdl.handle.net/10962/d1003985.

Texto completo da fonte

Resumo:

The heat shock protein-70 (Hsp70) family of molecular chaperones are ubiquitous highly conserved proteins that are critical for the viability of cellular homeostasis. The ATPase activity of Hsp70 proteins is critical to their function as the affinity of a given Hsp70 for non-native substrate is modulated by ATP binding and hydrolysis. When bound to ATP, Hsp70s possess a low affinity for a given substrate protein, while the hydrolysis of ATP to ADP causes a conformational change that results in a high affinity for substrate proteins. The basal ATPase activity of Hsp70s is too low to facilitate their function in vivo, and co-chaperones are essential to modulate the efficient protein folding by Hsp70. Heat shock protein-40 (Hsp40) heat shock proteins are essential for the in vivo function of Hsp70s by stimulating the ATPase activity of these proteins and facilitating transfer of substrates. The Type III class of Hsp40 proteins have not been well characterised due to their poor levels of conservation at the primary sequence level. This is due to the fact that Type III Hsp40s only contain a J-domain and a poorly conserved C-terminal region. The newly identified Type IV class of Hsp40s, contain an abrogated HPD tripeptide motif in the J-domain and have also not been extensively studied. Trypanosoma brucei (T. brucei) is a unicellular flagellated protozoan parasite. It is the causative agent of Human African Trypansomiasis (HAT) which results in thousands of deaths and devastating agricultural losses in many parts of Africa. T. brucei undergoes a complex lifecycle that is characterised by the transition from an insect vector to a mammalian host in markedly different conditions of temperature, pH, nutrient availability and respiratory requirements. It has been proposed that molecular chaperones may enhance the survival of these parasites due to their cytoprotective effect in combating cellular stress. Due to the fact that T. brucei infection is invariably fatal if left untreated, and that no novel treatment regimens have been developed recently, the identification of potential novel drug targets among proteins essential to the parasite’s survival in the host organism is an attractive aspect of T. brucei research. Because Type III Hsp40s are poorly conserved with respect to Hsp40s found in the human host, the identification of any of these proteins found to be essential to T. brucei survival in humans could potentially make attractive novel drug targets. An in depth in silico investigation into the Type III Hsp40 complement as well as partner Hsp70 proteins in T.brucei was performed. T. brucei possesses 65 Hsp40 proteins, of which 47 were classed as Type III and 6 of which were identified as being putative Type IV Hsp40s. A small but significant number (5) of Type III TbHsp40s contained tetratricopeptide (TPR) domains in addition to the J-domain. The J-domains of the Type III TbHsp40 complement were found to be conserved with respect to those of canonical Hsp40 proteins, although the mutation of certain residues that play a key role in Hsp40-Hsp70 interaction was noted. Potential partnerships of these proteins in the parasite was also investigated. The coding regions of three previously uncharacterised TbHsp40s were successfully amplified from T. brucei TREU927 genomic DNA and cloned into an expression vector. Tbj1, a Tcj1 ortholog, was selected for further study and successfully expressed and biochemically characterised. Tbj1 expressed in E. coli was found to be insoluble, but large amounts were recovered with the aid of a denaturing purification followed by refolding elution strategies, and the bulk of the protein recovered was in compact monomeric form as determined by size-exclusion chromatography fast protein liquid chromatography (SEC-FPLC). The addition of Tbj1 to a thermally aggregated substrate resulted in increased levels of aggregation, although Tbj1 was able to assist two Hsp70 proteins in the suppression of aggregation. Tbj1 proved unable to stimulate the ATPase activity of these same Hsp70s, and could not rescue temperature sensitive cells when replacing E.coli DnaJ and CbpA. It was concluded that Tbj1 does not possess independent chaperone activity, but could display Hsp40 co-chaperone properties under certain circumstances. This could allude to a specialised function in the T. brucei parasite. The lack of human orthologues to Tbj1 could result in the attractiveness of this protein as a novel drug target.

Estilos ABNT, Harvard, Vancouver, APA, etc.

14

Liljeholm, Maria. "Congenital Dyserythropoietic Anemia type III (CDA III) : diagnostics, genetics and morbidity". Doctoral thesis, Umeå universitet, Institutionen för strålningsvetenskaper, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-117454.

Texto completo da fonte

Resumo:

The Congenital Dyserythropoietic Anemias (CDA) are rare hereditary hemolytic disorders with large bi- to multi-nucleated erythroblasts in the bone marrow. Hemolysis is negative in a direct antiglobulin test (DAT). Based on morphology and clinical picture, three major forms of CDAs, type I, II, and III have been defined. CDA III, dominantly inherited, constitutes the rarest type with a majority of cases belonging to a family in Västerbotten, Sweden. The genetic background of CDA I and CDA II has been linked to mutations in CDAN1 and SEC23B respectively. The mutation of CDA III has been linked to 15q22 in earlier studies. In this project we have defined the causative genetic lesion in two families with CDA III. The novel mutation KIF23 c.2747C>G (p.P916R) was shown to segregate with CDA III in the Swedish and American CDA III families and was absent in 356 healthy controls. KIF23 encodes mitotic kinesin-like protein 1 (MKLP1), which plays a central role in the last step of cytokinesis. RNAi-based knock-down and rescue experiments demonstrated that the p.P916R mutation causes cytokinesis failure in HeLa cells, resulting in increasing number of bi-nuclear cells, consistent with appearance of large multinucleated erythroblasts in CDA III patients. We conclude that CDA III is caused by a mutation in KIF23, encoding MKLP1, a conserved mitotic kinesin crucial for cytokinesis. Flow cytometry with eosin-5´-maleimide (EMA), anti-CD55 and anti-CD59 is commonly used when investigating non-autoimmune hemolytic anemias. Reduced fluorescence of EMA, typically detected in hereditary spherocytosis, is also seen in CDA II, while reduction of CD55 and CD59 characterizes paroxysmal nocturnal hemoglobinuria (PNH). We studied the flow cytometric profile of EMA, CD55, and CD59 on erythrocytes in CDA III. We found no abnormality of the erythrocyte membrane in CDA III and concluded that standard flow cytometry cannot be used to discriminate between CDA III and normal controls. In CDA I and CDA II a majority of patients, including those who are not transfusion dependent, suffer from iron overload, which, according to earlier studies, is not the case in CDA III. We found that individuals of the Västerbotten CDA III family carry mutations in the hemochromatosis (HFE) gene. Three CDA III patients with heterozygous or compound HFE mutations need treatment with phlebotomy due to iron overload. One of them carries heterozygous H63D mutation, which is not reported to lead to iron overload by itself in otherwise healthy individuals. We propose that molecular genetic testing of the HFE gene is indicated in all patients with CDA, including CDA III.

Estilos ABNT, Harvard, Vancouver, APA, etc.

15

Bode, M. (Michaela). "Characterization of type I and type III collagens in human tissues". Doctoral thesis, Oulun yliopisto, 2000. http://urn.fi/urn:isbn:9514255534.

Texto completo da fonte

Resumo:

Abstract Fibrillar type I and III collagens are the major constituents of the extracellular matrix, providing the tissue with tensile strength and influencing cell attachment and migration. The amount of type III collagen and the extent of its processing and cross-link maturation were studied in human atherosclerotic plaques, abdominal aortic aneurysms, colon and ovarian cancer, and finally, colon diverticulosis, using a novel radioimmunoassay for the cross-linked aminoterminal telopeptide of type III collagen. In addition, immunoassays for different structural domains of type I and type III collagens, together with immunohistochemical methods, were applied. In atherosclerotic plaques, the fully cross-linked type III collagen was the major collagen type. Type III collagen was completely processed, since the amount of type III pN-collagen was negligible. The amounts of free type I and III procollagen propeptides in the soluble fraction were small, indicating a low rate of collagen turnover. The proportion of type III collagen was lower in abdominal aortic aneurysms than in atherosclerotic aortic control samples. Furthermore, the amount of type III pN-collagen was significantly increased in aneurysms. Type I and III collagens were also maturely cross-linked in colon diverticulosis, the only difference from normal colon tissue being the increased amount of the aminoterminal propeptide of type III procollagen in the soluble tissue extract, indicating a slightly increased metabolic activity of type III collagen. In malignant ovarian tumors, the cross-linking of type I and III collagens was defective. A similar trend was also seen for type I collagen in colon cancer. Even though procollagen synthesis was increased in these malignancies, the total collagen content and the amounts of cross-linked collagens were decreased. The amount of type III pN-collagen was increased in malignant ovarian tumors, whereas no such tendency was seen in colon cancer. These findings suggest a wide variety of changes in the metabolism of type I and III collagens in diseases. Defective processing and cross-link maturation of these collagen types might result in impaired fibril formation or increased susceptibility of collagens to proteolytic attack - both of them processes with a potential role in the pathogenesis of diseases.

Estilos ABNT, Harvard, Vancouver, APA, etc.

16

Peplinski, Adam. "Numerical simulations of type III planetary migration". Doctoral thesis, Stockholm University, Department of Astronomy, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-7461.

Texto completo da fonte

Resumo:

Planets are believed to form in primordial gas-dust discs surrounding newborn stars. An important breakthrough in our understanding of planetary formation was the discovery of extra-solar planets around sun-like stars, especially the frequent occurrence of giant planets on close orbits (hot Jupiters). The mechanisms involved in the formation of these objects remain uncertain, however the difficulties associated with their formation at their observed orbital radius has awoken an interest in theories for the migration of protoplanetary cores due to gravitational interaction with the disc. There are three fundamental regimes of planet migration. The type I and II migration regimes, driven by the differential Lindblad torques, result mostly in inward migration and concern low- and high-mass planets respectively. Type III migration, driven by the co-orbital gas flow, concerns an intermediate range of planetary masses and does not have a predefined direction.

In this thesis the orbital evolution of a high-mass, rapidly (type III) migrating planet is investigated using numerical hydrodynamical simulations. For these simulations we used the state-of-the-art hydrodynamics code FLASH. We focus on the physical aspects of type III migration. However, the problem of rapid migration of such massive planets is numerically challenging, and the disc model has to be chosen carefully, using numerical convergence as a discriminator between models (Paper I). We simulate both inward and outward directed migration (Papers II and III) and provide an extensive description of the co-orbital flow responsible for driving the migration, as well as its time evolution. The migration rate due to type III migration is found to be related to the mass of the planet's co-orbital region, making inward and outward directed migration self-decelerating and self-accelerating processes respectively (for a standard disc model). Rapid migration depends strongly on the flow structure in the planet's vicinity, which makes it sensitive to the amount of mass accumulated by the planet as it moves through the disc. This quantity in turn depends on the structure of the accretion region around the planet. The results of the numerical simulations show a good agreement with the analytical formulation of type III migration (Paper IV).

Estilos ABNT, Harvard, Vancouver, APA, etc.

17

Singh, Mona P. "Type III secretion in enteropathogenic Escherichia coli". Thesis, Imperial College London, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.486563.

Texto completo da fonte

Resumo:

Type III secretion systems (T3SS) are complex multi-component structures that are utilised in two biological contexts: translocation ofbacterial effector proteins into eukaryotic cells and flagellar protein export. The two types ofT3SS share a conserved core set ofhomologous proteins which are integrated into a larger apparatus that includes a hol1'ow filamentous surface extension, which comprises the flagellar hook and filament, or the needle and the translocation apparatus in the case of flagellar or non-flagellar systems, respectively. Enteropathogenic Escherichia coli (EPEC) and enterohaemorrhagic E. coli (EHEC) are human gut pathogens that utilise a T3SS encoded by the locus of enterocyte effacement (LEE) and exploit a hollow filamentous extension to the needle, termed the EspA filament, for the passage of effector proteins directly from the bacterial cytoplasm into host cells. The mechanism of assembly ofthe EspA filament remains elusive, however similarities between the flagella and EspA filaments and their subunits allow comparisons to be drawn regarding their mechanism ofassembly. To this end, several aspects encompassing the structure, function and assembly ofthe EspA subunit and EspA filament were investigated in this study. Firstly the recently identified EspA N-terminal coiled coil domain was characterised, highlighting structural and stabilising roles in EspA filament assembly. Secondly, the potential for the EspA subunit to form an intra-subunit coiled-coil interaction and polymerise through inter-subunit interactions in a similar manner to flageIIin was illustrated. Thirdly, it was shown that there may be variation in the molecular basis of antigenic polymorphism displayed by EspA filaments between different EPEC and EHEC clonal lineages.

Estilos ABNT, Harvard, Vancouver, APA, etc.

18

Baker, M. G. "Investigations on the type-III rearrangement problem". Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372877.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

19

Martin-Touaux, Elsa. "Caractérisation physiopathologique de la glycogénose de type II et développement de différentes approches thérapeutiques sur un modèle murin de la maladie". Paris 7, 2003. http://www.theses.fr/2003PA077235.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

20

Ulander, Anna Karin. "KIF23 expression in congenital dyserythropoietic anemia type III". Thesis, Umeå universitet, Biomedicinsk laboratorievetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-57964.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

21

Billings, K. S. "Studies on core-swapped fibronectin type III domains". Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.596637.

Texto completo da fonte

Resumo:

Two homologous fibronectin type III (fnIII) domains, FNfn10 (the tenth fibronectin type III domain of human fibronectin) and TNfn3 (the third fibronectin type III domain of human tenascin), have, essentially, the same backbone structure although they share only ~24% of sequence identity. FNoTNc is a core swapped protein, containing the “outside” (surface and loops) of FNfn10 and the hydrophobic core of TNfn3. Despite the extent of redesign, FNoTNc retains the structure of the parent proteins allowing us to gain insights into which components of each parent protein are responsible for different aspects of its behaviour. Naively, one would expect properties that depend principally on the core to be similar to TNfn3, for example the response to mutation, folding kinetics and sidechain dynamics; while properties determined by difference in the surface and loops, such as backbone dynamics, would be more like FNfn10. While this is broadly true, it is clear that there are also crosstalk effects between the core and surface. For example, the anomalous response of FNfn10 to mutation is not solely a core property as we had previously suggested. TNoFNc is a core swapped protein, containing the “outside” (surface and loops) of TNfn3 and the hydrophobic core of FNfn10. We infer from our data that TNoFNc has also retained the structure of the parent proteins. TNoFNc is a very unstable protein, which we suggest is due to over-packing of the core. An attempt was made to characterise mutants of TNoFNc, although our investigations were hampered by the presence of a possible impurity which may copurify with the mutant proteins. However, it is clear that the mutants appear to behave very differently to wild-type TNoFNc.

Estilos ABNT, Harvard, Vancouver, APA, etc.

22

Li, Zhiya. "New Bismuth(III)-catalyzed Sakurai type Allylation Reactions". Thesis, Université Laval, 2010. http://www.theses.ulaval.ca/2010/27512/27512.pdf.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

23

Pallett, Mitchell. "Characterisation of the type III secretion effector NleF". Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/28244.

Texto completo da fonte

Resumo:

The human-specific enteropathogenic Escherichia coli and the mouse-restricted Citrobacter rodentium colonise the host intestinal mucosa via attaching and effacing lesions, inducing severe diarrhoeal disease and transmissible murine colonic hyperplasia, respectively. C. rodentium is widely used as an in vivo model for EPEC infection, sharing a highly homologous arsenal of virulence factors and a similar infection strategy with EPEC. EPEC and C. rodentium pathogenesis relies on the locus of enterocyte effacement-encoded type III secretion system and delivery of effectors into the host cytosol to subvert host cell signalling including: actin dynamics, cell trafficking and immune signalling. The role of many effectors during infection remains unclear. We sought to identify the function of the non-LEE-encoded effector protein F (NleF). We discovered that EPEC infection of polarised epithelial cells activated a caspase-4-dependent non-canonical inflammasome response leading to the processing and secretion of IL-18, which was counteracted in a T3SS- and NleF-dependent manner. EPEC NleF interacts with the p20 and p10 subunits of caspase-4, associating with the substrate-binding domain, to inhibit its proteolytic activity and downstream inflammasome activation. Infection of mice with a C. rodentium nleF mutant enhanced IL-18 secretion and revealed that NleF is essential for the inhibition of the caspase-1/11-dependent inflammasome and recruitment of neutrophils in vivo. We further report that ectopically expressed NleF activated NF-κB nuclear translocation and the up-regulation of the pro-inflammatory chemokine IL-8. Infection of HeLa with an EPEC nleF deletion mutant abolished the T3SS-dependent activation of NF-κB and the expression of IL-8. NleF was identified to act upstream to IκBα activation and could be inhibited by the TAB2/3 inhibitor NleE1. However the mechanism of the pro-inflammatory role of NleF remains unclear. These findings identify novel roles for the T3SS effector NleF, furthering our understanding of the infection strategy of EPEC and the host epithelial cell inflammasome response.

Estilos ABNT, Harvard, Vancouver, APA, etc.

24

Benrabah, Sabria. "Passivation des matériaux III-N de type GaN". Thesis, Lyon, 2021. http://www.theses.fr/2021LYSE1310.

Texto completo da fonte

Resumo:

Pour répondre aux demandes de développement de nouveaux produits dans les domaines des convertisseurs électroniques de puissance pour les voitures électriques, des panneaux solaires, des éoliennes et des nouvelles technologies d'éclairage à base de LED ou de composants RF, la recherche s'est concentrée sur les matériaux à large bande interdite directe, dont le nitrure de gallium (GaN). Le GaN a suscité un grand intérêt en raison de ses propriétés exceptionnelles pour les dispositifs électroniques de puissance de la prochaine génération. Avec une vitesse de saturation élevée et une tension de fonctionnement élevée, les dispositifs à base de GaN peuvent fonctionner à haute fréquence et avec un excellent rendement, ce qui fait du GaN un matériau de choix dans les applications de puissance. Cependant, le développement des matériaux III-N est encore immature, notamment en ce qui concerne le contrôle de la qualité des différentes interfaces au sein des dispositifs. La présence d'une forte densité d'états d'interfaces peut être à l'origine de dysfonctionnements du dispositif. Par conséquent, la compréhension et le contrôle de la surface du GaN constituent un défi pour une éventuelle intégration industrielle future. Aujourd'hui, il n'existe pas de préparation de surface standard appropriée et efficace pour le GaN. Afin d'étudier ce problème, ce projet de thèse a été réalisé dans le cadre d'une collaboration entre le CEA-LETI (Grenoble), le LTM (Grenoble) et les laboratoires CP2M (Catalyse, Polymérisation, Procédés et Matériaux, Lyon). Les principaux objectifs de ce projet sont, d'une part, de comprendre la chimie de surface suite à différentes préparations de surface, et d'autre part, de mettre en place la configuration des liaisons de surface. Ce projet de thèse s'est donc concentré sur la préparation et la caractérisation de l'extrême surface de GaN après divers traitements chimiques et physiques
To meet demands for the development of new products in the fields of power electronic convertors for electric cars, solar panels, wind turbines, and new LED-based lightening technologies or RF components, research has focused on direct wide bandgap materials, including Gallium Nitride (GaN). GaN has attracted significant interest due to its exceptional properties for next-generation power electronic devices. With a high saturation velocity and a high operating voltage, GaN-based devices can operate at high frequency and with excellent efficiency, making GaN a material of choice in power applications. However, the development of III-N materials is still immature, especially in terms of quality control of the various interfaces within the devices. The presence of high density of interfaces states can be the cause of device malfunctions. Therefore, understanding and controlling the surface of GaN is a challenge for possible future industrial integration. Today, there is no suitable and effective standard surface preparation of GaN. In order to investigate this problem, this PhD project was carried out in a collaboration between CEA-LETI (Grenoble), LTM (Grenoble) and CP2M laboratories (Catalysis, Polymerisation, Process and Materials, Lyon). The main objectives of this project are, first, to understand the surface chemistry following various surface preparations, and second, to set up the configuration of surface bonds. Therefore, this PhD project focused on the preparation and characterisation of the extreme surface of GaN after various chemical and physical treatments

Estilos ABNT, Harvard, Vancouver, APA, etc.

25

SPOSITO, BENEDETTA. "Type III Interferons: Running Interference with Mucosal Repair". Doctoral thesis, Università degli Studi di Milano-Bicocca, 2023. https://hdl.handle.net/10281/402377.

Texto completo da fonte

Resumo:

Gli interferoni (IFN) sono mediatori e regolatori fondamentali della risposta immunitaria dell'ospite a virus e ad altri agenti microbici. Gli IFN di tipo I e di tipo III (o IFN-λ) sono tra le prime citochine ad essere indotte in seguito a infezioni virali. Il legame tra gli IFN e i rispettivi recettori attiva vie di trasduzione del segnale simili tra loro che inducono l'espressione di geni stimolati dagli IFN (ISG) con funzioni antivirali. La caratteristica principale che rende ciascuna di queste famiglie di IFN unica e non ridondante è l'esistenza di recettori distinti che fanno sì che gli IFN-I attivino una risposta ubiquitaria e che gli IFN-III agiscano esclusivamente sulle cellule epiteliali e su un sottoinsieme di cellule immunitarie. Ulteriori distinzioni riguardano la natura meno infiammatoria degli IFN-III e la loro induzione solitamente anticipata rispetto a quella degli IFN-I. Pertanto gli IFN-III sono considerati i difensori di prima linea delle mucose con la capacità di attivare una risposta antivirale precoce senza causare danno tissutale. Se la loro azione risulta insufficiente a contenere l’infezione, il sistema passa all’induzione degli IFN-I, i quali generano una risposta antivirale e infiammatoria più potente e a livello sistemico, che tuttavia può portare ad immunopatologia. Nel corso della mia tesi ho verificato l'ipotesi secondo cui anche gli IFN-III possano causare immunopatologia, in particolare durante infezioni virali delle vie respiratorie e in contesti di danno all’epitelio gastrointestinale in malattie infiammatorie croniche intestinali e lesioni da radiazioni. In primo luogo, io e i miei colleghi abbiamo dimostrato che in un polmone in cui è stata indotta una risposta antivirale, gli IFN-III prodotti dalle cellule dendritiche inibiscono la proliferazione delle cellule epiteliali portando ad una compromissione del rigenerazione della barriera e ad un aumento della suscettibilità ad infezioni batteriche. In seguito abbiamo analizzato la produzione di IFN lungo il tratto respiratorio di pazienti affetti da COVID-19. Abbiamo trovato che, nelle alte vie aeree, l'espressione di IFN-I/III correla con la carica virale e che negli anziani, che presentano un maggiore rischio di sviluppare una patologia severa, questa correlazione è più debole o assente. Una forte espressione di IFN-λ1, IFN-λ3 e ISG caratterizza le alte vie aeree di pazienti con sintomatologia lieve, mentre risultano fortemente espressi gli IFN-I, IFN-λ2 e un insieme di geni antiproliferativi e proapoptotici lungo tutto il tratto respiratorio di pazienti ospedalizzati, suggerendo che possano ostacolare il processo di riparazione dell’epitelio. Infine, abbiamo dimostrato che gli IFN-III ritardano la rigenerazione dell'intestino tenue e del colon in seguito a danno da radiazioni o da colite indotta da destrano sodio solfato, poiché contribuiscono a indurre la morte cellulare delle cellule epiteliali tramite la formazione di un complesso proteico costituito da Z-DNA binding protein (ZBP1) e gasdermin C (GSDMC). I nostri risultati mettono in discussione il ruolo degli IFN-III come protettori delle mucose poiché indicano che quando non propriamente regolati possono causare immunopatologia. Queste evidenze portano alla necessità di progettare l’uso clinico degli IFN di tipo III in modo da evitare le loro funzioni dannose per i tessuti e massimizzarne gli effetti benefici.
Interferons (IFNs) are fundamental mediators and regulators of the host immune response to viruses and other microbial agents. Type I and type III IFNs (also known as IFN-λ) are some of the first cytokines to be induced upon detection of viral infections. Signaling through their specific receptors leads to the activation of a similar signaling cascade that triggers the expression of a common set of IFN-stimulated genes (ISGs) with antiviral effector functions. The main feature that makes each of these families of IFNs unique and nonredundant is the existence of distinct receptors that differentiate them in their ability to act on virtually every cell type (type I IFNs) or exclusively on epithelial cells and a subset of immune cells (type III IFNs). Despite inducing a widely overlapping set of genes, IFN-I can mount a stronger proinflammatory response compared to IFN-III. This, coupled with the earlier induction of IFN-III upon infection, has led to the classification of IFN-III as front-line defenders of mucosal surfaces with the ability to initiate an early antiviral response with minimal tissue-damaging effects. If their response is insufficient the system shifts to the more potent and broader-acting antiviral and inflammatory IFN-I response that can cause immunopathology. In the course of my thesis, I have tested the hypothesis that also IFN-III contribute to immunopathology at barrier sites such as the respiratory and gastrointestinal epithelia during viral infections and inflammatory bowel disease/radiation-induced injury respectively. First, my colleagues and I found that in a mouse model where we mimicked the induction of antiviral responses in the respiratory tract, IFN-III produced by lung dendritic cells inhibited the proliferation of lung epithelial cells leading to an impairment in barrier restoration and an increase in susceptibility to bacterial infections. Then we measured IFN responses along the respiratory tract of COVID-19 patients. We uncovered that in the upper airways expression of IFN-I/III correlated with viral load and elderly patients, that have a higher risk of developing severe COVID-19, had a dysregulation in the IFN response. A strong expression of IFN-λ1, IFN-λ3 and ISGs characterized the upper airways of mild patients. IFN-I and IFN-λ2 together with antiproliferative and proapoptotic genes were upregulated along all the respiratory tract of severe COVID-19 patients, suggesting that they might contribute to the impairment of epithelium restitution. Finally, we demonstrated that IFN-III delayed colon and small intestine repair after dextran sulfate sodium-induced colitis and radiation-induced injury by triggering cell death of epithelial cells via the formation of a novel protein complex that includes Z-DNA binding protein (ZBP1) and gasdermin C (GSDMC). Our findings challenge the role of IFN-III as protectors of mucosal barriers as they indicate that a dysregulated IFN-III response holds the potential to contribute to immunopathology. Therefore, the clinical use of type III IFNs should be designed in such a way that their tissue-damaging functions are avoided and their beneficial effects are maximized.

Estilos ABNT, Harvard, Vancouver, APA, etc.

26

Gjorgjieva, Monika. "Identification des mécanismes moléculaires impliqués dans le développement des pathologies hépatiques et rénales dans des modèles murins de glycogénose de type 1a". Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1007/document.

Texto completo da fonte

Resumo:

La glycogénose de type I (GSDI) est une maladie génétique rare, due à une déficience en glucose-6 phosphatase (G6Pase), enzyme clé de la production endogène de glucose. En plus des hypoglycémies sévères, la perte de l'activité G6Pase conduit à l'accumulation de glycogène, mais aussi de lipides dans le foie et les reins. A long-terme, la plupart des patients développent des tumeurs hépatiques et une maladie rénale chronique (MRC).Le but de cette thèse a été de caractériser les mécanismes moléculaires impliqués dans la carcinogenèse hépatique et la MRC grâce à des modèles murins viables et uniques, avec une délétion de la G6Pase spécifiquement dans le foie ou les reins, reproduisant respectivement toutes les caractéristiques de la pathologie hépatique ou rénale.Au niveau du foie, notre étude a permis de mettre en évidence une reprogrammation métabolique « Warburg-like » très similaire à celle des cellules cancéreuses, associée à une perte des défenses cellulaires et des suppresseurs de tumeur. De plus, nous avons montré que les adénomes hépatocellulaires, se transformant ensuite en carcinomes, se développent en absence de fibrose, en accord avec l'absence d'activation des voies pro-fibrotiques. Au niveau des reins, l'étude de la MRC a mis en évidence le développement de kystes rénaux chez les souris atteintes de GSDI, observés aussi chez les patients à un stade avancé de la MRC. Finalement, une dernière étude portant sur l'activation de l'oxydation des lipides, par un traitement des souris au fénofibrate, a permis de suggérer le rôle délétère de l'accumulation des lipides dans le développement des pathologies hépatique et rénale
Glycogen storage disease type I (GSDI) is a rare genetic disease, due to a deficiency in glucose-6 phosphatase (G6Pase), a key enzyme in the endogenous glucose production. Besides severe hypoglycemia, the loss of G6Pase leads to the accumulation of glycogen and lipids in the liver and kidneys. On the long term, most patients develop hepatic tumors and chronic kidney disease (CKD).The goal of this thesis was to characterize the molecular mechanisms involved in hepatic carcinogenesis and CKD, thanks to viable and unique mouse models with specific deletion of G6Pase in the liver or kidneys, which exhibit all hallmarks of hepatic and renal pathologies, respectively.On a hepatic level, our study allowed us to highlight a « Warburg-like » metabolic reprogramming, very similar to what is observed in cancer cells, associated with a loss of cellular defenses and tumor suppressors. Furthermore, we showed that formation of hepatocellular adenoma, which transform later in carcinoma, occurs in the absence of liver fibrosis, due to the fact that pro-fibrotic pathways are not activated. In the kidneys, the study of CKD highlighted the development of renal cysts in mice with GSDI, as well as in the patients presenting an advanced stage of CKD. Finally, the last study on the activation of the oxidation of lipids, by treating the mice with fenofibrate, allowed us to suggest a deleterious role of lipid accumulation in the development of the hepatic and renal pathologies

Estilos ABNT, Harvard, Vancouver, APA, etc.

27

Gjorgjieva, Monika. "Identification des mécanismes moléculaires impliqués dans le développement des pathologies hépatiques et rénales dans des modèles murins de glycogénose de type 1a". Electronic Thesis or Diss., Lyon, 2018. http://www.theses.fr/2018LYSE1007.

Texto completo da fonte

Resumo:

La glycogénose de type I (GSDI) est une maladie génétique rare, due à une déficience en glucose-6 phosphatase (G6Pase), enzyme clé de la production endogène de glucose. En plus des hypoglycémies sévères, la perte de l'activité G6Pase conduit à l'accumulation de glycogène, mais aussi de lipides dans le foie et les reins. A long-terme, la plupart des patients développent des tumeurs hépatiques et une maladie rénale chronique (MRC).Le but de cette thèse a été de caractériser les mécanismes moléculaires impliqués dans la carcinogenèse hépatique et la MRC grâce à des modèles murins viables et uniques, avec une délétion de la G6Pase spécifiquement dans le foie ou les reins, reproduisant respectivement toutes les caractéristiques de la pathologie hépatique ou rénale.Au niveau du foie, notre étude a permis de mettre en évidence une reprogrammation métabolique « Warburg-like » très similaire à celle des cellules cancéreuses, associée à une perte des défenses cellulaires et des suppresseurs de tumeur. De plus, nous avons montré que les adénomes hépatocellulaires, se transformant ensuite en carcinomes, se développent en absence de fibrose, en accord avec l'absence d'activation des voies pro-fibrotiques. Au niveau des reins, l'étude de la MRC a mis en évidence le développement de kystes rénaux chez les souris atteintes de GSDI, observés aussi chez les patients à un stade avancé de la MRC. Finalement, une dernière étude portant sur l'activation de l'oxydation des lipides, par un traitement des souris au fénofibrate, a permis de suggérer le rôle délétère de l'accumulation des lipides dans le développement des pathologies hépatique et rénale
Glycogen storage disease type I (GSDI) is a rare genetic disease, due to a deficiency in glucose-6 phosphatase (G6Pase), a key enzyme in the endogenous glucose production. Besides severe hypoglycemia, the loss of G6Pase leads to the accumulation of glycogen and lipids in the liver and kidneys. On the long term, most patients develop hepatic tumors and chronic kidney disease (CKD).The goal of this thesis was to characterize the molecular mechanisms involved in hepatic carcinogenesis and CKD, thanks to viable and unique mouse models with specific deletion of G6Pase in the liver or kidneys, which exhibit all hallmarks of hepatic and renal pathologies, respectively.On a hepatic level, our study allowed us to highlight a « Warburg-like » metabolic reprogramming, very similar to what is observed in cancer cells, associated with a loss of cellular defenses and tumor suppressors. Furthermore, we showed that formation of hepatocellular adenoma, which transform later in carcinoma, occurs in the absence of liver fibrosis, due to the fact that pro-fibrotic pathways are not activated. In the kidneys, the study of CKD highlighted the development of renal cysts in mice with GSDI, as well as in the patients presenting an advanced stage of CKD. Finally, the last study on the activation of the oxidation of lipids, by treating the mice with fenofibrate, allowed us to suggest a deleterious role of lipid accumulation in the development of the hepatic and renal pathologies

Estilos ABNT, Harvard, Vancouver, APA, etc.

28

Costa, Tiago R. D. "YopD translocator function in Yersinia pseudotuberculosis type III secretion". Doctoral thesis, Umeå universitet, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-61544.

Texto completo da fonte

Resumo:

Type III secretion systems (T3SS) are a common feature of Gram-negative bacteria, allowing them to inject anti-host effectors into the interior of infected eukaryotic cells. By this mechanism, these virulence factors help the bacteria to modulate eukaryotic cell function in its favor and subvert host innate immunity. This promotes a less hostile environment in which infecting bacteria can colonize and cause disease. In pathogenic Yersinia, a crucial protein in this process is YopD. YopD is a T3S substrate that, together with YopB, forms a translocon pore in the host cell membrane through which the Yop effectors may gain access to the target-cell cytosol. The assembly of the translocator pore in plasma membranes is considered a fundamental feature of all T3SSs. How the pore is formed, what determines the correct size and ultimately the stoichiometry between YopD YopB, is still unknown. Portions of YopD are also observed inside HeLa cells. Moreover, YopD functions together with its T3S chaperone, LcrH, to control Yops synthesis in the bacterial cytoplasm. The multifunctional YopD may influence all these processes by compartmentalizing activities into discrete modular domains along the protein length. Therefore, understanding how particular domains and/or residues within these regions coordinate multiple functions of the protein will provide a platform to improve our knowledge of the molecular mechanisms behind translocation through T3SSs. Comprehensive site-directed mutagenesis of the YopD C-terminal amphipathic α-helix domain, pinpointed hydrophobic residues as important for YopD function. Some YopD variants were defective in self-assembly and in the ability to interact with the needle tip protein, LcrV, which were required to facilitate bacterial T3S activity. A similar mutagenesis approach was used to understand the role of the two predicted coiled-coils located at the N-terminal and C-terminal region of YopD. The predicted N-terminal element that occurs solely in the Yersinia YopD translocator family is essential for optimal T3SS and full disease progression. The predicted YopD C-terminal coiled-coil shapes a functional translocon inserted into host cell membranes. This translocon was seen to be a dynamic structure facilitating at least two roles during effectors delivery into cells; one to guarantee translocon pore insertion into target cell membranes and the other to promote targeted activity of internalized effector toxins. In Yersinia expression of yop genes and secretion of the corresponding polypeptides is tightly regulated at a transcriptional and post-transcriptional level. If T3S chaperones of the translocator class are known to influence transcriptional output of T3SS genes in other bacteria, we show that in Yersinia the class II T3S chaperone LcrH has no such effect on the LcrF transcriptional activator activity. We also demonstrate that there are possibly additional yop-regulatory roles for the LcrH chaperone besides forming a stable complex with YopD to impose post-transcriptional silencing on Yops synthesis. This mechanism that relies upon an active T3SS, might act independently of both YopD and the regulatory element LcrQ. In conclusion, this work has sought to delineate the encrypted functions of the YopD translocator that contribute to Yersinia T3SS-dependent pathogenesis. Contributions of the YopD cognate chaperone LcrH in yop regulatory control are also presented.

Estilos ABNT, Harvard, Vancouver, APA, etc.

29

Xiao, Yanmei. "Regulation of type III secretion system in Pseudomonas syringae". Diss., Manhattan, Kan. : Kansas State University, 2005. http://hdl.handle.net/2097/130.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

30

Main, Alison. "Structural and functional studies of fibronectin type III molecules". Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359449.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

31

Xu, Xuefang. "Regulation of type III secretion in enterohaemorrhagic Escherichia coli". Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5941.

Texto completo da fonte

Resumo:

Enterohaemorrhagic Escherichia coli (EHEC) strains are associated with gastrointestinal and severe systemic disease in humans. EHEC O157:H7 is the most common serotype causing human infections in North America and the UK. Human infections mainly originate from cattle, through either direct contact with infected animals or indirectly through contamination of food or water with animal faeces. From the sequencing of EHEC O157 strains, it is clear that the genomes contain multiple prophages, many of them cryptic, which define this E. coli pathotype. These regions include the locus of enterocyte effacement (LEE) which is a critical horizontally acquired pathogenicity island and encodes a type III secretion system (T3SS). The T3SS translocates effector proteins into epithelial cells that enable tight attachment to these host cells and also modify innate responses and other cellular functions to promote persistence in the animal host. The T3SS is essential for the colonisation of cattle by EHEC O157 where it is localised to the terminal rectum. The regulation of T3S is complex with many regulators and environmental factors already identified. Previous work has demonstrated marked variation in the levels of T3S among EHEC O157 strains. The aim of this research was to further investigate the regulation of T3S towards two objectives: (1) to understand the localisation of EHEC O157 at the terminal rectum of cattle; (2) to understand the strain variation in T3S. (1) In relation to rectal and mucosal colonisation, established aerobic/anaerobic regulators were investigated including arcA, fnr, narX, narQ. Briefly, arcA, fnr, narX, narQ were deleted in an E. coli O157 strain ZAP198 by lambda red recombination. Apart from the fnr mutant which showed lower levels of T3S, the remaining mutants displayed similar T3S protein levels compared to the wild type strain. In addition, no significant changes in adherence and A/E lesion formation capacity were measured for the mutants following interaction with bovine epithelial cells. (2) Strain secretion variation was approached in two ways; the first was to control expression from the LEE1 operon, required for T3S expression, in order to both induce expression and examine the importance of downstream regulation. The second was to investigate variation in T3S between different phages types of EHEC O157. While attempts to construct an inducible T3SS were not successful, intermediate strains made in the process have been useful to dissect how regulators being studied in the laboratory control T3S. The main novel insights from the research have come from examining T3S in different EHEC O157 phage types. We found that the average level of T3S in PT 21/28 strains was lower than in PT 32 strains. Interestingly, most (90%) of PT 21/28 strains contained both Stx2 and Stx2c phages. In contrast, only 28% of PT 32 strains had both phages. Taken together, this raised the possibility that Stx phage integration might have a repressive impact on T3SS regulation in E.coli O157:H7. This hypothesis was addressed using a number of different approaches. Deletions of Stx phages were constructed and these had increased levels of T3S when compared to the parental strains. This phage regulation of T3SS was confirmed in an E. coli K12 background by examining an induced LEE1 reporter in the presence and absence of a transduced Stx2 phage. In addition, it was shown that deletion of the CII phage regulator led to increased T3S and may contribute to the Stx phage repression reported above. This work demonstrates for the first time that Stx phage integration represses T3S expression. It is proposed that this control may limit immune exposure of this critical colonisation factor and that the repression actually allows activation by prophage encoded regulators, including PchA/B, that co-ordinate T3S and non LEE-encoded effector expression to promote epithelial cell colonisation.

Estilos ABNT, Harvard, Vancouver, APA, etc.

32

Röhrich-Dönitz, Anelia Dorothea. "Regulation of type III secretion hierarchy in Shigella flexneri". Thesis, University of Bristol, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.633196.

Texto completo da fonte

Resumo:

Type III secretion systems (T3SS) are protein injection devices used by Gram-negative bacteria to manipulate eukaryotic cells. In Shigella, the T3SS is assembled when the environmental conditions are appropriate for invasion. However, secretion is only activated when physical contact of the injection needle with the host cell generates an activation signal. The signal is transmitted to the cytoplasm where it triggers secretion. First, translocators are secreted which form a pore in the host cell membrane. Second, effector proteins are translocated into the host cell. The activation process is controlled by conserved T3SS components: the needle tip proteins IpaD and IpaB, the needle itself and the intracellular gate-keeper protein MxiC. The major tip protein IpaD provides a scaffold for pore-forming translocators. In its absence no needle tip is formed, the T3SS secretes constitutively and is unable to sense host cell contact. Using random mutagenesis combined with a genetic screen we have mapped the region of IpaD required for activation signal generation/transmission and identified an additional intracellular role for IpaD in secretion control. Thus, IpaD has a dual role in secretion regulation. The gate-keeper protein MxiC is a cytoplasmic protein that plays a key role in mediating secretion hierarchy. In its absence, the secretion of translocator proteins is decreased and effector proteins are leaked. We have used site-directed mutagenesis, genetics and analysis of native protein complexes to further characterise its function. While MxiC seems to be a predominantly cytoplasmic and monomeric protein, we show that it acts in the same intracellular pathway as IpaD to control translocator secretion. We have identified the areas of MxiC required for activation signal reception, promoting translocator secretion, blocking premature effector secretion and for regulating its own secretion. We also provide evidence that a conformational change in MxiC might be involved in its function. Taken together, our work suggests how cytoplasmic mechanisms block premature secretion of translocators and effectors and in which steps secretion activation might occur.

Estilos ABNT, Harvard, Vancouver, APA, etc.

33

Gunasena, Deepthi Kaushalya. "Type III secretion systems in bacterial pathogens of fish". Thesis, University of Reading, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.413881.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

34

Thomas, Joanne. "Functional analysis of flagellum-specific type III export chaperones". Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615655.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

35

Ahmed, Essa Ismaeil. "Type III Deep Eutectic Solvents (DESS) as base lubricants". Thesis, University of Leicester, 2015. http://hdl.handle.net/2381/33465.

Texto completo da fonte

Resumo:

Mineral oils are the most commonly used fraction of formulated lubricating oils except for some specialised applications where synthetic oils are employed. An alternative approach has been suggested using ionic liquids (ILs) due to their high viscosity index and high thermal stability. The aim of this study is to examine the use a different type of ionic liquids in the form of Deep Eutectic Solvents (DESs) as base lubricants as these have significantly improved environmental credentials. The first stage of the study involved the investigation of thermo-physical properties such as heat capacity, thermal stability, surface tension, viscosity index, melting point, conductivity and density to determine if the liquids are suitable fluids as lubricants. The data for a variety of imidazolium based ILs and standard mineral base oil were also determined and used for comparison sake. In addition the properties of DES mixtures with water were determined and self-diffusivity were measured using NMR spectroscopy. It was shown for the first time that aqueous DES mixtures are not homogeneous but instead they form bicontinuous micro-emulsions. This study has also been the first to quantify the corrosion rates of metals in DESs and ionic liquids. The corrosion of iron, aluminium and nickel was studied in four DESs and four ILs using both Tafel slope analysis and electrochemical impedance spectroscopy. The corrosion rate was found to change over time for some liquids and so the corrosion product films were characterised using Raman spectroscopy. The interfacial properties of DES and ILs are shown to be totally different from mineral base oil and the wettability in terms of contact angle and interfacial energies for various metals have been studied. The friction coefficient and wear volume were measured for DESs for dissimilar sliding couples. Finally, the change of both thermo-physical and mechanical properties due to the inclusion of two common surfactants sodium dodecylsulfate and cetyltrmethylammonium bromide are characterised in three DESs and shown to decrease the wear volume.

Estilos ABNT, Harvard, Vancouver, APA, etc.

36

Wang, Zhibo. "Functional Characterization of Four Xanthomonas euvesicatoria Type III Effectors". Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/104984.

Texto completo da fonte

Resumo:

Pepper and tomato, as two common, popular, and important vegetables grown worldwide, provide human beings with high quality fruit of flavor and aroma, and a high concentration of vitamins and antioxidants. Pepper and tomato production is frequently affected by various pathogens, including nematodes, fungi, and bacteria. Among those phytopathogens, Xanthomonas euvesicatoria (Xe) causes a severe bacterial spot (BS) disease on pepper and tomato. The BS disease could cause a loss of approximately 10% of the total crop yield in the world. Breeding tomato and pepper cultivars with improved BS disease resistance is one of the most important breeding goals. A better understanding of the virulence mechanism of Xe could help breeders design new strategies for resistance breeding. In this dissertation, we characterized the virulence and avirulence functions of four Xe Type Three Secretion Effectors (T3Es): Xe-XopQ, Xe-XopX, Xe-XopN, and Xe-avrRxo1. Xe-XopQ is a Xe T3E that functions as a determinant of host specificity. Here, we further explored the virulent and avirulent functions of Xe-XopQ. We identified another T3E Xe-XopX that could interact with XopQ and subsequently elicit the hypersensitive response in N. benthamiana in the Agrobacterium-mediated transient assay and Xe-mediated disease assay. The interaction is confirmed by bimolecular fluorescence complementation, co-immunoprecipitation and split luciferase assay. Intriguingly, we also revealed that XopX also interacts with multiple Xe T3Es including AvrBS2, XopN, XopB, and XopD in the co-IP assay. The virulent and avirulent functions of XopQ and AvrBS2 are compromised in the absence of Xe-XopX. Since XopX is conserved in diverse Xanthomonas spp., we speculate that Xe-XopX may have a general role required for the pathogenesis of Xe. Xe-XopN has been reported to be a T3E with virulence function via targeting host defense-related proteins, including atypical receptor-like kinase named TARK1 and a 14-3-3 protein to suppress the PAMPs (pathogen-associated molecular patterns) triggered immunity upon Xe colonization of tomato. In this study, we revealed additional virulence mechanisms of Xe-XopN, where Xe-XopN, is required for triggering the water-soaking symptom on Nicotiana benthamiana and pepper plants infected with Xe. In addition, we identified that XopN interacts with a transcription factor, NbVOZ, and represses the expression of NPR1, a key component of the basal defense. Therefore, XopN has a role in maintaining a water-affluent environment for better replication of Xe, and it can also interact with NbVOZ1/2 to regulate plant immunity. AvrRxo1, a T3E of Xanthomonas oryzae pv. oryzicola (Xoc), was previously identified to function as a NAD kinase. Here, we characterized a Xe T3E, Xe avrRxo1, that is a functional homologue of AvrRxo1, which is required for the full virulence of Xe to colonize the pepper and N. benthamiana plants. Overexpression of AvrRxo1 in bacterial or plant cells is toxic. Our group previously demonstrated AvrRxo1-ORF2 functions as an antitoxin that binds to AvrRxo1 to suppress its toxicity. In this study, we identified Xe4429 as the homologue of AvrRxo1-ORF2, which could interact with Xe-avrRxo1 to suppress its toxicity. We also revealed that Xe4429 could bind to the promoter of Xe-avrRxo1 and suppress its transcription. Therefore, we found Xe4429 encodes protein functions as an antitoxin and a transcription repressor in Xe bacterial cells.
Doctor of Philosophy
Peppers and tomatoes are two of the most important vegetables grown worldwide, providing humans with high quality of flavor and aroma, vitamins, and antioxidants. The pepper and tomato production is frequently threatened by various pathogens, including nematodes, fungi, and bacteria. Among those phytopathogens, Xanthomonas euvesicatoria (Xe) causes a severe bacterial spot (BS) disease on peppers and tomatoes. The BS disease can be easily identified due to the appearance of the dark, irregular, water-soaked areas on the leaf, which can cause approximately 10% loss of the total yield of peppers and tomatoes. Breeding tomato and pepper cultivars with improved BS disease resistance is one of the most critical breeding goals. A better understanding of the virulence mechanism of Xe could help breeders to design new strategies for resistance breeding. In my seminar, I will discuss the virulence and avirulence functions of Xe type three secretion (T3S) effectors: Xe XopN, Xe XopQ, and Xe XopX. In my study, I identified Xe XopN is a key factor that regulates the development of the water-soaking symptom on pepper plants infected with Xe. In addition, we revealed Xe XopN interacts with a transcription factor NbVOZ to regulate the expression of NbNPR1 and PR1 genes expression, which may also contribute to the development of water-soaking phenotype. In addition, I identified that Xe XopN could interact with a transcription factor, NbVOZ, and represses the expression of NbNPR1, a key component of the basal defense, and the pathogenesis-related gene PR1. Therefore, Xe XopN has a role in regulating a water-affluent environment to promote bacterial proliferation in the infected plant tissue. Xe XopQ is a Xe T3S effector that functions as a determinant of host specificity. In my study, I identified another T3S effector Xe XopX that could interact with Xe XopQ to trigger the defense response in Nicotiana benthamiana. I also confirmed Xe XopQ physically interacts with Xe XopX inside of plant cells by using bimolecular fluorescence complementation, co-immunoprecipitation and split luciferase assay. Intriguingly, Xe XopX could also interact with multiple Xe T3Es including AvrBS2 in a co-IP assay. The virulence and avirulent functions of Xe XopQ and AvrBS2 are compromised in the absence of Xe XopX.

Estilos ABNT, Harvard, Vancouver, APA, etc.

37

Bronstein, Philip Alan. "Identification and characterization of a type III chaperone, InvB /". Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/11524.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

38

Steed, Robert John. "Saturation of Intersubband Transitions in p-type and N-type III-V Qua'ntum Wells". Thesis, Imperial College London, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.487524.

Texto completo da fonte

Resumo:

Intersubband transitions (ISBTs) in quantum wells have had extensive prior research but remain interesting. This thesis continues the use of saturation experiments for the characterisation of ISBT relaxation times ie. the time taken for carriers to scatter between a quantum well's subbands. Saturation experiments were carried out using an optical parametric generator as a tunable source of mid-infrared laser light (6.4 --t 8.6 pm) and intensities of -200MWcm-2 were reached. For this thesis, two p-doped samples were saturated, each sample containing multiple GaAs/AIGaAs quantum wells. Both sample's quantum wells had two confined heavy hole levels and the ISBTs between them, had energies of 160meV and 183meV (respectively). The hhl-hh2 ISBTs were saturated for each sample, the measured carrier relaxation times were 0.3 Ã‚Â± 0.1 ps and 2 Ã‚Â± 1.4 ps respectively, indicating that relaxation occurred via LO phonon emission (for comparison, an n-type quantum well with an ISBT of similar energy would have a relaxation time between 0.3 --t 0.6 ps). The effect of circularly polarised light on the carrier dynamics ofn-doped GaAs/AIGaAs quantum wells was also investigated. Circularly polarised light can lead to spin-sensitive ISBTs; this has been shown to lead to a change in the ISBT's saturation intensity for circularly polarised light due to the addition of the spin-relaxation time to the carrier dynamics. For this thesis, saturation experiments were performed using light incident at an oblique incidence to the QWs (via a novel sample geometry) but no significant differences in saturation intensity were {ound between using circularly and linearly polarised light.

Estilos ABNT, Harvard, Vancouver, APA, etc.

39

Lin, Herbert Y. (Herbert Yih-Fuu). "Expression cloning and characterization of the type II and type III TGF-β receptors". Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/12507.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

40

Mandaliev, Peter Nikolov. "Mechanisms of Nd(III) and Eu(III) uptake by cementitious materials /". [S.l.] : [s.n.], 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=18095.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

41

Podrebarac, James. "Development of Recombinant Human Collagen Type I and Type III Injectable Hydrogels for Cardiac Therapy". Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36038.

Texto completo da fonte

Resumo:

Functional biomaterials are being developed as scaffolds to support endogenous cells and to promote the regeneration of ischemic tissue. The aim for this study was to develop a new translational platform for injectable hydrogels using recombinant human collagen (rHC) of two types: type I (TI) and type III (TIII). The collagen solutions were characterized to ensure batch-to-batch consistency and protein integrity. The hydrogel preparation protocol was extensively monitored to ensure ease of use and high-quality production. Post-gelation, rHC TIII have a higher viscosity compared to rHC TI, yet water content was high for both hydrogels. The cross-linking degree is similar for both rHC hydrogels, which are stable well above physiological temperatures, but rHC TI is more susceptible to enzymatic degradation than rHC TIII. Furthermore, the micro-architecture differed with pore size dimensions of rHC TIII being significantly larger than that of rHC TI. Cardiac fibroblasts were cultured on the rHC hydrogels, and cells attached readily to the scaffold environment, which promoted proliferation. The rHC matrices mechanical and biological properties provide structural support, and demonstrate biodegradability and biocompatibility. The intrinsic physical differences between the rHC hydrogels will likely have implications in future studies. In conclusion, the rHC TI and TIII hydrogels are proven to be suitable matrices for continued investigation towards future translational applications.

Estilos ABNT, Harvard, Vancouver, APA, etc.

42

Dendy, Shauneen Marguerite. "Cholesterol synthesis in type III hyperlipoproteinemic and non-hyperlipidemic individuals". Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/28979.

Texto completo da fonte

Resumo:

The purpose of this study was to investigate whether increased endogenous cholesterol synthesis contributes to the elevated plasma cholesterol levels observed in type III hyperlipoproteinemia (type III HLP). Eight apolipoprotein (apo) E2 subjects with type III HLP and 8 apo E2 non-hyperlipidemic control subjects (controls) were given a priming bolus dose of deuterium oxide (D₂O) (0.7 g D₂O/kg body H2O). Daily M1 (central) pool free cholesterol fractional synthetic rate (FSR) was calculated as the incorporation rate of deuterium from body water into plasma free cholesterol. Blood samples were collected one half hour prior to, and at 12 hour intervals over 48 hours following, the bolus D₂O dose. Drinking water labelled at 1.4 and 0.7 g D₂O/liter H₂O was given on the fed and fasted days, respectively. Over 0-24 hours, subjects consumed a diet of three isocaloric meals which, in composition, approximated average North American intakes. Subjects fasted over 24-48 hours. The deuterium enrichment of plasma free cholesterol and plasma water was determined by isotope ratio mass spectrometry. When all subjects were included, mean (±SEM) free cholesterol overall FSR in type III HLPs (0.031 ± 0.006 per day) was not significantly different from controls (0.037 ± 0.004 per day). Estimated Ml total cholesterol pool size in type III HLPs (26.1 ± 1.9 g) and controls (24.9 ± 0.6 g) was not significantly different. When free cholesterol net synthesis was calculated as the absolute amount of cholesterol synthesized per day, based on Ml total cholesterol pool size, overall free cholesterol net synthesis in type III HLPs (0.304 ± 0.034 g/day) was not significantly different from controls (0.364 ± 0.035 g/day). When all subjects were included, overall free cholesterol FSR and overall free cholesterol net synthesis were significantly greater (p<0.001) in the fed (0.066 ± 0.006 day⁻¹ and 0.655 + 0.048 g/day, respectively) as compared to the fasted state (0.001 ± 0.004 day⁻¹ and 0.010 ± 0.037 g/day, respectively). In the fed state, type III HLPs tended to synthesize cholesterol at a lower rate and in a lower absolute amount as compared to controls, while the reverse was observed in the fasted state. These results suggest that: (1) the elevated plasma cholesterol levels observed in type III HLPs are not due to excess de novo cholesterol synthesis; (2) fasting significantly reduces cholesterol synthesis from the fed state.
Land and Food Systems, Faculty of
Graduate

Estilos ABNT, Harvard, Vancouver, APA, etc.

43

Rodgers, Loren E. "Recognition of effectors by the bacterial type III secretion system". Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3307124.

Texto completo da fonte

Resumo:

Thesis (Ph. D.)--University of California, San Diego, 2008.
Title from first page of PDF file (viewed July 2, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.

Estilos ABNT, Harvard, Vancouver, APA, etc.

44

Robin, Ekman. "The GHP formalism, with applications to Petrov type III spacetimes". Thesis, Umeå universitet, Institutionen för fysik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-88352.

Texto completo da fonte

Resumo:

We give a review of the construction and application of spinor fields in general relativity and an account of the spinor-based Geroch-Held-Penrose (GHP) formalism. Specifically, we discuss using the GHP formalism to integrate Einstein's equations as suggested by Held and developed by Edgar and Ludwig and discuss the similaritites with the Cartan-Karlhede classification of spacetimes. We use this integration method to find a one-parameter subclass and a degenerate case, for which the Cartan-Karlhede algorithm terminates at second order, of the Petrov type III, vacuum Robinson-Trautman metrics. We use the GHP formalism to find the Killing vectors, using theorems by Edgar and Ludwig. The one-parameter family admits exactly two Killing fields, whereas the degenerate case admits three and is Bianchi type VI. Finally we use the Cartan-Karlhede algorithm to show that our class, including the degenerate case, is equivalent to a subclass found by Collinson and French. Our degenerate case corresponds to an example metric given by Robinson and Trautman and is known to be the unique algebraically special vacuum spacetime with diverging rays and a three-dimensional isometry group.

Estilos ABNT, Harvard, Vancouver, APA, etc.

45

Mitsopoulos, Konstantinos. "The assembly of type III membrane proteins in Escherichia coli". Thesis, University of Sussex, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310262.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

46

Elliott, Jayne Louise. "Properties and interactions of type III intermediate filaments with CRYAB". Thesis, Durham University, 2013. http://etheses.dur.ac.uk/7017/.

Texto completo da fonte

Resumo:

Glial fibrillary acidic protein is a type three intermediate filament found within astrocytes in the central nervous system and mutations have been found as the cause of Alexander disease, resulting in protein aggregates of Rosenthal fibers with αBcrystallin. Here two glial fibrillary acidic protein mutants of R79C and R239H, located in the LNDR and rod 2A domain respectively, were assembled in vitro and their morphology, assembly competence and interactions with αB-crystallin were assessed. Both mutants were unable to form usual filament lengths but instead were similar to unit length filaments with R239H forming aggregates due to such high protein interactions and the R79C mutant having much lower assembly competent protein interactions. R239H had a much greater affinity for αB-crystallin, likely a reflection that it has one of the most severe phenotypes. An absence of divalent cations equally affected GFAP assembly resulting in compromised compaction and increased filament-filament interactions. The R120G αB-crystallin mutant results in cardiomyopathy and cataract due to aberrant interactions with desmin intermediate filaments, due to an increased oligomer size and therefore these interactions were studied and compared to wild-type interactions. Temperature and pH also alter the oligomer size of αB-crystallin and were therefore investigated with αB-crystallin-type III intermediate filament interactions. It was found that ischemic conditions and increased temperatures promote their association, demonstrated by increased co-pelleting under high speed sedimentations. There was a preference for binding to desmin filaments thus showing how desmin-wild-type αB-crystallin interactions are important for homeostasis in muscle. Passive microrheology was used to complement this and investigate how αB-crystallin may be modulating desmin filaments under equilibrium. From these experiments wild-type αB-crystallin reduced the frequency-dependent passive viscosity η(f) and the G’, whereas the cardiomyopathy- and cataract- causing R120G mutant increased the η(f).

Estilos ABNT, Harvard, Vancouver, APA, etc.

47

Zhang, Weiqiang. "Synthesis of novel chiral pyrrolidine-type (salen)Mn(III) complexes". Thesis, Swansea University, 2006. https://cronfa.swan.ac.uk/Record/cronfa42403.

Texto completo da fonte

Resumo:

The thesis reports the total syntheses of new chiral pyrrolidine-type salen ligands 5.4 and their corresponding Mn(III) complexes 5.5. The salen ligands were synthesized by condensation of tras-(3R,4R)-diaminopyrrolidine (3.12) or trans-(3R,4R)-1-benzyl-3,4-diaminopyrrolidine (3.10) with two equivalents of (R)-3-formyl-2-hydroxy-2'-phenyl-1,1'-binaphthalene [(R)-4.9]. The salen ligands were transformed to their corresponding Mn(III) complexes following a general procedure. The catalytic performances of the synthesized (salen)Mn(III) complexes in asymmetric epoxidation of 1,2-dihydronaphthalene were tested. In chapter 1, a review of asymmetric epoxidation of alkenes is given. Emphasis is placed on the development and some of the important designs of chiral salen ligands and their corresponding (salen)Mn(III) complexes. In chapter 2, the nature of the research project is outlined. In chapter 3, the syntheses of trans-(3R,4R)-diaminopyrrolidine trihydrochloride salt (3.9), trans-(3R,4R)-1-benzyl-3,4-diaminopyrrolidine (3.10) and its trihydrochloride salt (3.11) are reported. These compounds were prepared from (2R,3R)-(-i-)-tartaric acid via multi-step syntheses. Extensive studies on optimization of these transformations are reported. Chapter 4 records the synthesis of (R)-3-formyl-2-hydroxy-2'-phenyl-1,1'-binaphthalene [(R)-4.9] from 2-naphthol via a seven-step synthetic procedure. Extensive studies on these transformations are described, especially on the oxidative coupling of 2-naphthol and on the optical resolution of racemic 2,2'-dihydroxy-1,1'-binaphthalene. In chapter 5, the preparations of salen ligands 5.4 and their corresponding Mn(III) complexes 5.5 are reported. The applications of synthesized Mn(III) complexes in asymmetric epoxidation of 1,2-dihydronaphthalene were carried out. In chapter 6, an overall conclusion of the work is given.

Estilos ABNT, Harvard, Vancouver, APA, etc.

48

Wu, Shuchi. "Structural and functional characterization of a Xanthomonas Type III effector". Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/73219.

Texto completo da fonte

Resumo:

Rice bacterial leaf streak disease caused by Xanthomonas oryzae pv. oryzicola (Xoc) is one of the most important rice bacterial diseases. Xanthomonas type III effector gene avrRxo1 is conserved in diverse Xoc strains and its homologues have been identified from several other gram-negative bacteria species such as Burkholderia and Acidovorax. In this research, we studied the protein structure of AvrRxo1 and illustrated its virulence mechanism.We determined the three-dimensional structure of the complex of AvrRxo1 and its cognate chaperone Arc1 (AvrRxo1 required chaperone 1). The AvrRxo1: Arc1 complex is structurally similar to the Zeta-epsilon family of toxin: antitoxin systems from the human bacterial pathogen Streptococcus pyogenes. AvrRxo1 and Arc1 have toxin: antitoxin-like activity in bacteria, and the toxin activity of AvrRxo1 is required for its virulence function in planta. These findings suggest that AvrRxo1 evolved from an endogenous bacterial toxin-antitoxin system.Furthermore, AvrRxo1 was shown to have virulence functions in diverse host plants including Arabidopsis thaliana. The ectopic expression of wild type avrRxo1 in Arabidopsis suppresses plant basal defense. AtVOZ (Arabidopsis vascular one zinc-finger transcription factor), which has two homologues in the Arabidopsis genome, VOZ1 and VOZ2, was identified as one of AvrRxo1 candidate interactor. The knockout of voz1/voz2 renders the plants more susceptible to the virulent pathogen Pseudomonas syringae pv. tomato (Pst) DC3000, but compromises the virulence function of AvrRxo1. The expression profiling of transgenic Arabidopsis plants expressing the avrRxo1 gene allowed us to identify Arabidopsis genes regulated by AvrRxo1 and VOZ1/2. AvrRxo1 interacts with and stabilizes VOZ2 in vivo and directly binds to the promoter region of AtCYS2 (Arabidopsis phytoCYStatin 2) to induce its expression. The overexpression of CYS2 in increased stomatal aperture size, and enhanced plant susceptibility to Pst. Therefore one of AvrRxo1 virulent functions is to regulate the expression of CYS2 by manipulating VOZ2, resulting in increased stomatal aperture. Presumably, this renders the host leaf more susceptible to colonization via the stomata. Another component of my dissertation was based on a genome-wide survey of Arabidopsis papin-like cysteine protease genes (PLCPs). The Arabidopsis genome has 31 PLCP and 7 cystatin genes, and they often worked in pairs to regulate signaling pathways in response to biotic and abiotic stress. The coordinated transcriptional regulation of all Arabidopsis PLCP and cystatin genes has never been systematically investigated. In order to unveil the mechanism of stomata-related plant immunity regulated by CYS2, we analyzed the expression patterns of 28 PLCPs and 7 cystatins in Arabidopsis in response to biotic or abiotic stress, by reprocessing and integrating microarray data from the AtGenExpress database. We also performed enzyme assays and evaluated the inhibition specificity of seven cystatins to the five most abundant PLCPs in Arabidopsis. Finally, we utilized the SVMs (support vector machines) package in R software to predict a functional network of PLCP-cystatin interplay in Arabidopsis. We identified the PLCP protein PAP4 as one of the putative targets of CYS2. The co-expression profiling indicated that the expression patterns of PAP4 and CYS2 were strongly correlated during virulent bacterial infection, and weakly correlated under drought stress. Therefore, PAP4 was determined to be a promising gene in regulating stomatal aperture size. Further research on the interplay of PAP4-CYS2 could be important for understanding AvrRxo1's virulence mechanism and regulation of plant stomatal immunity.
Ph. D.

Estilos ABNT, Harvard, Vancouver, APA, etc.

49

Legrand, Isabelle. "Glycogenose de type iii : a propos de deux nouveaux cas". Université Louis Pasteur (Strasbourg) (1971-2008), 1986. http://www.theses.fr/1986STR1M169.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

50

Shan, Libo. "Characterization of type III effectors of Pseudomonas syringae pv. tomato /". Search for this dissertation online, 2003. http://wwwlib.umi.com/cr/ksu/main.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Teses / dissertações sobre o tema "Glycogénose de type III"

Crie uma referência precisa em APA, MLA, Chicago, Harvard, e outros estilos