Este estudo caso-controle teve por objetivo comparar as angulações e inclinações dentárias em casos de má oclusão de Classe I pré e pós-tratamento ortodôntico e em casos de oclusão normal. A amostra consistiu nos modelos dentários em gesso de 18 indivíduos com má oclusão de Classe I (3 homens e 15 mulheres; idade 15,12 ± 1,42 anos), tratados com exodontias de primeiros pré-molares e mecânica de deslize por meio da técnica MBT® com ancoragem por mini-implantes. Estes indivíduos foram pareados por idade com outros 18 indivíduos com oclusão normal não tratada (7 homens e 11 mulheres; idade 14,9 ± 1,0 anos). Os modelos dentários em gesso foram escaneados tridimensionalmente e, em seguida, os modelos digitais foram encaminhados para o programa Power Shape-e® (Delcam®, Birminghan, Reino Unido) para mensuração das angulações e inclinações dentárias. O teste t de Student foi empregado para análise dos dados. Os resultados não apontaram diferenças significantes entre os lados direito e esquerdo (p > 0,05). O tratamento da má oclusão de Classe I impôs uma significativa diminuição nas angulações de caninos e segundos molares superiores e um aumento das inclinações vestibulares das coroas de incisivos laterais superiores, segundos pré-molares, primeiros e segundos molares inferiores. Verificou-se que uma maior angulação dos caninos e pré-molares inferiores contribuiu para a caracterização da má oclusão de Classe I, assim como uma redução na angulação dos incisivos laterais superiores. Os casos de má oclusão de Classe I pós-tratamento, em comparação com os indivíduos com oclusão normal, apresentaram significativas diminuições nas angulações de segundos molares, caninos e incisivos laterais superiores e de segundos molares inferiores e aumentos significativos nas angulações de segundos pré-molares, caninos e incisivos inferiores. Houve também redução das inclinações dentárias de primeiros e segundos molares inferiores no grupo tratado. Portanto, as alterações nas angulações e inclinações contribuíram para a correção da má oclusão de Classe I e para a aproximação com os valores do grupo com oclusão normal. / This case-control study aimed at comparing dental angulation and inclination in cases with Class I malocclusion pretreatment and posttreatment and in cases with normal occlusion. The sample consisted of dental plaster models of 18 subjects with Class I malocclusion (3 males and 15 females, aged 15.12 ± 1.42 years), treated by first premolars extractions and sliding mechanics by MBT® technique with miniimplants for anchorage. These individuals were age-matched with 18 patients with untreated normal occlusion (7 men and 11 women, aged 14.9 ± 1.0 years). The dental plaster models were scanned three-dimensionally, and then the digital models were referred to the software Power Shape-e® (Delcam®, Birmingham, UK) for measurement of angulations and inclinations. The Student t test was used for statistical analysis. The results did not show significant differences between the right and left sides (p> 0.05). The treatment of Class I malocclusion imposed a significant decrease in the angulation of upper canines (U3) and second molars (U7) and an increase in the buccal inclination of the crowns of upper lateral incisors (U2), lower second premolars (L5), first (L6) and second molars (L7). It was found that an increase in the angulation of lower canines (L3) and premolars (L4 and L5) contributed to the characterization of the Class I malocclusion, as well as a decrease in the angulation of U2. Posttreatment cases of Class I malocclusion, compared with normal occlusion, showed significant decreases in the angulation of U7, U3, U2 and L7 and significant increases in the angulation of L5, L3 and lower incisors (L1 and L2). There was also a decrease in inclinations of L6 and L7 in the treated group. Therefore, changes in angulations and inclinations contributed to correction of Class I malocclusion.

L’ubiquitinylation a été largement étudiée comme étant un mécanisme impliqué dans la régulation du trafic intracellulaire de nombreuses protéines membranaires. Mon travail a permis d’identifier MARCH-IX, une ubiquitine ligase exprimées dans les cellules de mammifères, comme un acteur important du trafic intracellulaire des molécules de présentation antigénique CD1a et CMH-I. En condition d'over-expression, MARCH-IX ubiquitinyle spécifiquement CD1a et CMH-I. Par ailleurs, en utilisant la technique d’ARN interférence, nous avons mis en évidence que l’ubiquitination des CMH I dépendante de MARCH IX facilite l’export des CMH I néosynthétisés du TGN vers la membrane plasmique et permet leur accès à des compartiments endosomaux. Notamment l’expression de MARCH-IX est régulée au niveau transcriptionnel pendant la maturation de DCs humaine; son expression est largement diminuée suite à l’activation des DCs plasmacytoïdes (pDCs), alors qu’elle augmente dans des DCs dérivées de monocytes (MoDCs) stimulées par du LPS. Ces résultats laissent envisager que MARCH IX puisse avoir un rôle important dans le contrôle de la présentation antigénique médiée par les CMH I dans les DCs humaines. Enfin, l’adressage intracellulaire des molécules de CD1a dans les MoDCs apparait également comme un processus régulé au cours de la maturation. Si CD1a est localisé à la membrane plasmique et dans des compartiments endosomaux précoce dans des cellules immatures, cette molécule n’apparaît plus qu’à la surface des cellules matures. Nous postulons donc que la régulation de MARCH-IX durant la maturation des MoDCs puisse être directement liée à la modification du trafic intracellulaire de CD1a. / Ubiquitination has been largely studied as regulator of the intracellular trafficking of several membrane proteins, inducing their internalization or their sorting from TGN to endosomes. Interestingly, pathogens adopted this mechanism to evade the immune response. For example, Kaposi’s sarcoma herpesvirus synthesizes two ubiquitin ligases, MIR1 and MIR2, which target the antigen presenting molecule, MHC class I, inducing its internalization. We identified the mammalian ubiquitin ligase MARCH-IX as important factor in the intracellular trafficking of antigen presenting molecules, CD1a and MHC-I. In conditions of MARCH-IX over-expression, CD1a and MHC-I are ubiquitinated and they accumulated in early endosomes. In MARCH-IX silenced cells, the arrival of MHC-I at the plasma membrane appear to be delayed and MHC-I accumulates in the TGN. During dendritic cell maturation, MARCH-IX expression and CD1a intracellular localization showed a correlation, which is compatible with a role of the ubiquitin ligase in the export pathway of CD1a. We concluded that MARCH-IX acts on neo-synthesized molecules, facilitating their sorting from the TGN. In addition to the function analysis of MARCH-IX, we also investigated its ability to conjugate ubiquitin on non-conventional residues. Our results demonstrated that, differently from viral ubiquitin ligases, MARCH-IX could target MHC class I and CD1a only in presence of lysine residues on their cytoplasmic tail, suggesting a stronger restriction in the control of the ubiquitination mechanism on mammals.

No description available.

La tagatose-1,6-biphosphate aldolase de Streptococcus pyogenes est une aldolase de classe I qui fait montre d'un remarquable manque de spécificité vis à vis de ses substrats. En effet, elle catalyse le clivage réversible du tagatose-1,6-biphosphate (TBP), mais également du fructose-1,6-biphosphate (FBP), du sorbose-1,6-biphosphate et du psicose-1,6-biphosphate, quatre stéréoisomères, en dihydroxyacétone phosphate (DHAP) et en glycéraldéhyde-3-phosphate (G3P). Afin de mettre à jour les caractéristiques du mécanisme enzymatique, une étude structurale de la TBP aldolase de S. pyogenes, un pathogène humain extrêmement versatile, a été entreprise. Elle a permis la résolution de la structure native et en complexe avec le DHAP, a respectivement 1.87 et 1.92 Å de résolution. Ces mêmes structures ont permis de se représenter plus clairement le site actif de l'enzyme en général, et les résidus catalytiques en particulier. Le trempage des cristaux de TBP aldolase dans une solution saturante de DHAP a en outre permis de piéger un authentique intermédiaire iminium, ainsi que sa géométrie particulière en atteste. Des expériences d'échange de proton, entreprises afin d'évaluer le stéréoisomérisme du transfert de proton catalytique, ont également permis de faire une intéressante découverte : la TBP aldolase ne peut déprotoner le coté pro-R du C3 du DHAP, mais peut le protonner. Ce résultat, ainsi que la comparaison de la structure du complexe TBP aldolase-DHAP avec la structure du complexe FBP aldolase de muscle de lapin- DHAP, pointe vers un isomérisme cis-trans autour du lien C2-C3 de la base de Schiff formée avec le DHAP. De plus, la résolution de ces deux structures a permis de mettre en évidence trois régions très mobiles de la protéine, ce qui pourrait être relié au rôle postulé de son isozyme chez S. pyogenes dans la régulation de l’expression génétique et de la virulence de la bactérie. La cristallographie par rayons X et la cinétique enzymatique ont ainsi permis d'avancer dans l'élucidation du mécanisme et des propriétés structurales de cette enzyme aux caractéristiques particulières. / Tagatose-1,6-biphosphate aldolase from Streptococcus pyogenes is a class I aldolase that shows a lack of stereospecificity that is rare in enzymes in general, and in aldolases in particular. This aldolase catalyzes the reversible cleavage of tagatose-1,6-biphosphate (TBP), fructose-1,6-biphosphate (FBP), sorbose-1,6-biphosphate and psicose-1,6-biphosphate, four stereoisomers, in dihydroxyacetone phosphate and glyceraldehyde-3-phosphate (DHAP). In order to understand its mechanism, a structural study of TBP aldolase from S. pyogenes, one of the most versatile and virulent human pathogen, was initiated and high resolution crystallographic structures of native and DHAP-liganded TBP aldolase were solved. These structures allowed us to gain informations regarding active site residues implicated in catalysis and that give rise to the apparent lack of specificity. Soaking of TBP aldolase crystals in saturating DHAP solution specifically trapped the iminium intermediate, as demonstrated by its geometry. Furthermore, proton transfer studies uncovered an interesting phenomenon: TBP aldolase from S. pyogenes is unable to detritiate pro-R labelled hydrogen position at C3 of DHAP, yet it is able to tritiate both the pro-R and the pro-S position. These results, taken together with the superposition of the DHAP-TBP aldolase with the DHAP-FBP aldolase from rabbit muscle, suggest a cis-trans isomerism about the Schiff base C2-C3 bond. The resolution of both the native and the liganded structure also proved useful in identifying three very mobile regions in the protein. This trend could be linked to the putative metabolic sensor and genetic expression regulator role of LacD.1 in S. pyogenes. X-rays crystallography and traditional enzymatic kinetics allowed us to gain insights into the catalytic mechanism and others structural properties of this important metabolic enzyme.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

The results of experiments aimed at determining whether cytotoxic T lymphocytes (CTLs) can kill keratinocytes (KCs) expressing endogenously loaded antigen indicated that antigen specific cytotoxic T lymphocytes could recognize and kill keratinocytes expressing ovalbumin (OVA) or SIINFEKL peptide. Exposure of the KCs to interferon-gamma (IFN-γ) enhanced this CTL-mediated KC lysis and increased CTL epitope presentation on the surface of target cells. Expression of HPV 16 E7 protein in KCs affected CTL-mediated lysis. Expression of HPV 16 E7 inhibited IFN-γ-mediated up-regulation of SIINFEKL/H-2Kb complexes on keratinocytes, and also inhibited IFN-γ-mediated up-regulation of IRF-1 expression, and consequent up-regulation of TAP1 transcription. Further, overexpression of IRF-1 partially corrected the HPV 16 E7-mediated inhibition of enhanced susceptibility of KC lysis induced by IFN-γ. Thus, the effects of HPV 16 E7 on CTL-mediated lysis of IFN-γ exposed KCs are likely mediated by inhibition of MHC class I antigen presentation by IFN-γ. These findings may help explain why HPV-infected epithelial cells can escape from immune surveillance mediated by CTLs in vivo and in vitro.

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 4 uppsatser.

Thesis (Ph. D.)--University of Virginia, 2009. / Title from title page. Includes bibliographical references. Also available online through Digital Dissertations.

Name: Anna Jadwiga Kielkowska Dissertation title: The role of PTEN as a PI(3,4)P2 lipid phosphatase in Class I phosphoinositide 3-kinase signalling Abstract Class I phosphoinositide 3-kinases (Class I PI3Ks) are essential players involved in the signalling events in the cell and are critical promoters of cellular growth, survival and metabolism. Once activated by environmental stimuli such as growth factors, cytokines or antigens, they exert their catalytic activity by phosphorylating phosphatidylinositol (4,5)-bisphosphate (PI(4,5)P2) to yield a second messenger - PI(3,4,5)P3. Unrestrained PI(3,4,5)P3 signalling has been classically associated with hyperactivation of the Class I PI3K/AKT pathway and has been shown to be a molecular trigger of many pathophysiologies in humans, including autoimmune disorders, respiratory diseases and cancer. To date, two classes of lipid phosphatases SHIP1/2 and PTEN have been reported, which dephosphorylate PI(3,4,5)P3 on positions 5’ and 3’ of the inositol ring to generate PI(3,4)P2 and PI(4,5)P2 respectively, and thus quench Class I PI3K signalling. Moreover, PI(3,4)P2 levels in the cell are regulated by two important lipid 4-phosphatases - INPP4A/B. While the role of PTEN as a tumour suppressor is well established, functions of SHIP1/2 and INPP4A/B are just starting to emerge. A major barrier to progress in this field has been the lack of high quality measurements of PI(3,4)P2, to assess the impact it may have on shaping cellular behaviour. This dissertation summarises the work performed to develop a novel, HPLC-ESI MS/MS based method, in order to measure the product of PI(3,4,5)P3 5-dephosphorylation, PI(3,4)P2, separated from its more abundant regioisomer in cells - PI(4,5)P2. This and an existing HPLC-ESI MS/MS method for measuring PI(3,4,5)P3, have enabled us to describe the fluxes through Class I PI3K-controlled PI(3,4,5)P3 generation and its subsequent 3- and 5- dephosphorylation pathways in human mammary epithelial cells (Mcf10a) stimulated with epidermal growth factor (EGF). By means of genetic suppression of PTEN and INPP4B, we revealed an unexpectedly high level of PI(3,4)P2 that accumulates in EGF-stimulated PTEN-INPP4B-KO Mcf10a cells. Further, an in vitro biochemical assay suggested a novel role for PTEN as a direct PI(3,4)P2 3-phosphatase in Mcf10a cells. This important observation was supported by in sillico phosphatidylinositol lipid modelling of the relevant pathways. In an effort to understand its potential physiological significance, we demonstrated that PI(3,4)P2 accumulation correlates with the ability of genetically modified Mcf10a cells to form gelatin-degrading invadopodia. Finally, we used a mouse prostate cancer model to show PTEN’s importance in controlling PI(3,4)P2 levels in vivo, pointing to a potential role for PI(3,4)P2 in PTEN-dependent tumourigenesis. I hope that the work described in this dissertation will contribute to the current knowledge of phosphatidylinositol lipid biology in the context of Class I PI3K signalling and will simulate future efforts to gain an in-depth understanding of the roles of PTEN and PI(3,4)P2 in cellular physiology.