No description available.

Background: Arterial allografts are used as vascular conduits in the treatment of prosthetic graft infection. Immunosuppression decreases their rupture risk rate. However, immunosuppression can be unprofitable in florid infection. Previously, we confirmed inhibition of cell-mediated destruction of rat aortic grafts by delayed use of tacrolimus. In this work, we studied the influence of this protocol on the antibody-mediated rejection.

No description available.

The MHC class I allele, HLA-B27, is strongly associated with a group of inflammatory arthritic conditions collectively known as spondyloarthropathies (SpA). Ankylosing spondylitis (AS) shows the strongest association with 90-95 % of patients being HLA-B27 positive. The relationship between HLA-B27 and SpA has been known for over 30 years, however despite ongoing research, the reason for this association has not yet been elucidated. In more recent years, research has focused on intrinsic properties of the HLA-B27 allele, in particular its propensity to misfold, forming homodimers. It has been proposed that these homodimers could be associated with the disease process through the activation of an ER stress response known as the unfolded protein response (UPR), or through aberrant recognition at the cell surface. We have investigated whether the expression of HLA-B27 is associated with the activation of the UPR. We have studied the expression of BiP, and the cleavage of XBP1 and ATF6 using stable and transiently expressing cell lines. We have also investigated the formation of non-B27 homodimers using a human cell line stably expressing HLA-B8, and finally we have studied the expression of homodimers in exosomes, small immunomodulatory vesicles released from numerous cell types. The results presented here lead us to conclude that in vitro studies of the UPR are complicated, prone to a number of technical issues, and may therefore not be appropriate for gaining information that would be of significant use when comparing to the real disease scenario. Our data suggest that non-B27 dimers may be strongly influenced by both the overexpression of MHC class I heavy chains and also the redox environment within the cell. We have isolated a novel fully folded, beta-2m-associated, MHC class I homodimer in exosomes and have detected a novel HLA-A and HLA-B mixed heavy chain dimer. Our results suggest that these dimers form through interactions between the cysteine residues in the cytoplasmic tail and that these dimers form in exosomes because they contain lower levels of the important antioxidant glutathione when compared to whole cells. Together, these results define a new MHC class I structure present on exosomes at significant levels, which could potentially influence immune recognition by both antigen-specific T cell receptors and NK family receptors. The data also poses questions about whether these novel structures, when they involve HLA-B27, could influence the pathogenesis of spondyloarthropathies.

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.

OBJETIVO: o Fator-C é normalmente usado para predizer a tensão de contração em interfaces compósito-dente. Foi delineado um estudo para contribuir a esclarecer os elementos que permitem prever a tensão em interfaces de restaurações adesivas. Teoricamente, a tensão varia em função da oposição à contração (rigidez do substrato), da complacência e das dimensões e propriedades mecânicas do compósito. MÉTODOS: foram obtidos pelo Método de Elementos Finitos (MEF) 8 modelos estilizados 3D não-lineares de cavidades Classe I mantendo constantes o volume (20 mm3) e a espessura das paredes (20 mm) e com variação do Fator-C (1,9 a 13,5). Foi simulado contato tipo glue entre compósito e dente. A contração de polimerização, por analogia térmica do compósito, foi 1%. Foram analisadas as tensões e deformações principais. Foi também idealizado um método para calcular por MEF a complacência regionalizada e foi avaliada sua validade pela comparação do resultado obtido por este método com o valor de complacência calculada analiticamente para um cubo de dentina de 1 mm de lado fixado numa de suas faces. Foi ainda idealizado um método para calcular, para cada formato de cavidade, o volume útil de compósito capaz de influir para aumentar o pico de tensão na interface. Por fim, com os elementos anteriores, foi calculado para cada cavidade um valor de Fator-CA, dependente da complacência na região de pico e do volume útil de compósito. Foi avaliada a capacidade de predizer o pico de tensão mediante o teste de correlação (Pearson) entre o pico de tensão e o Fator-CA, bem como entre o pico de tensão e o Fator-C. RESULTADOS: os picos de tensões provocadas pela contração em cavidades de classe I tendem a diminuir em função do aumento do Fator-C, embora o teste de Pearson evidenciou significância apenas para a tensão Máxima Principal na parede XZ e no eixo Z. O cálculo da complacência regional obtido por MEF foi de 0,0652 m/N, bem próximo ao valor analítico (0,0666 m/N). O Fator-CA correlacionou significantemente e positivamente com as três tensões obtidas na quina (Von Mises, Máxima Principal e Máxima Cisalhante). CONCLUSÕES: o aumento do Fator-C não conduz ao aumento dos picos de tensão em cavidades de classe I. O método de cálculo de complacência é válido para estruturas complexas. O Fator-CA permite predizer os picos de tensão em compósitos aderidos em cavidades de classe I. / OBJECTIVES: The C-Factor is normally used to predict the shrinkage stress at composite-tooth interfaces. A study was outlined for clarifying the elements which allows providing the stress at bonded restorations interface. Theoretically, the stress varies as a function of the opposition to the shrinkage (substrate stiffness), the compliance, dimensions and mechanical properties of the composite. METHODS: Eight 3D non-linear stylized models of Class I cavities were obtained by the Finite Element Method (FEM), maintaining the volume (20 mm3) and wall thickness (2 mm) constant and varying the C-Factor (1.9 through 13.5). A \'glue\' contact between the composite and teeth was simulated. A 1% polymerization shrinkage was simulated by using thermal analogy of the composite. Principal stresses and strains were analyzed. A method for calculating the local compliance by FEM was also idealized as well as its validity of comparing the obtained result with the analytical compliance value of a 1 mm dentin cube, with fixation at one of its faces. A method for calculating, for each cavity shape, the \'useful volume\' of the composite, which is able to influence on the stress peak increase at the interface, was further idealized. And finally, using elements mentioned before, a compliance dependent value, so-called CA-Factor, was calculated for each cavity, at peak and \'useful volume\' of the composite regions. The capability on predicting the stress peak by the correlation test (Pearson) between the stress peak and the CA-Factor as well as between the stress peak and the C-Factor was also evaluated. RESULTS: the stress peaks generated by the shrinkage on Class I cavities tend to decrease as a function of the C-Factor, though the Pearson only showed the significance for the maximum principal stress at the XZ wall and Z axis. The local compliance calculation obtained by FEM was 0.0652 m/N, which was very close to the analytical one (0.0666 m/N). The CA-Factor presented a positive and significant correlation with all three stresses obtained at the trihedral angle formed by two occlusal edges. (Von Mises, maximum principal and maximum shear stresses). CONCLUSION: the increase of the C-Factor does not lead to the increase of the stress peaks in Class I cavities. The method for calculating the compliance is valid for complex structures. The CA-Factor allows providing the stress peaks for bonded composites on Class I cavities.

A estabilidade pós-tratamento sempre foi um assunto delicado da ortodontia. A maioria dos pacientes e até mesmo os ortodontistas, julgam o sucesso do tratamento ortodôntico pela estabilidade dos resultados em longo prazo. Por este motivo a literatura é repleta de estudos acerca deste assunto, principalmente da recidiva do apinhamento ântero -inferior. Já o interesse pelo apinhamento ânterosuperior e sua recidiva é crescente por conta de uma maior preocupação com a estética do sorriso. Desta forma, o propósito deste estudo é comparar a recidiva do apinhamento ântero-superior em pacientes com má oclusão de Classe I e Classe II de Angle. A amostra consiste em 70 pacientes divididos em 3 grupos. O Grupo 1 apresenta 30 pacientes (12 do gênero masculino e 18 do gênero feminino) com má oclusão de Classe I, idade média inicial de 13,16 anos e tratados com extrações dos 4 primeiros pré -molares. O Grupo 2 apresenta 20 pacientes (11 do gênero masculino e 9 do gênero feminino) com má oclusão de Classe II divisão 1, idade média inicial de 12,95 anos e também tratados com extrações dos 4 primeiros pré-molares. O Grupo 3 apresenta 20 pacientes (11 do gênero masculino e 9 do gênero feminino) com má oclusão de Classe II divisão 1, idade média inicial de 13,09 anos e tratados com extrações dos 2 primeiros pré -molares superiores. Foram avaliados os modelos de estudo nas fases inicial (T1), final (T2) e no mínimo 5 anos pós -tratamento (T3) de cada pac iente. As variáveis do arco superior avaliadas e comparadas estatisticamente pela Análise de Variância (ANOVA) foram: Índice de Irregularidade de Little superior (IRLS), comprimento do arco (CAS), distância intercaninos (DICS), interpré-molares (DI2PMS) e intermolares (DIMS). Como os resultados entre os grupos não mostraram diferenças estatisticamente significantes nas fases avaliadas, a amostra foi unificada. O Teste de Correlação de Pearson e o Teste de Regressão Linear Múltipla foram utilizados para veri ficar se alguma variável estudada teria influência sobre o apinhamento nas três fases (IRLS1, IRLS2, IRLS3). Os resultados mostraram que a recidiva do apinhamento superior (IRLS3-2) é influenciada pelo apinhamento inicial (IRLS1) e que os dentes tendem a voltar à posição original. O gênero feminino apresentou mais recidiva do apinhamento ântero -superior que o gênero masculino. / The posttreatment stability was always a delicate issue in Orthodontics. Most of the orthodontic patients and even the orthodontists judge their treatment as successful based on the treatment outcomes stability in the long-term. Because of this reason the literature has a lot of studies about this issue, mostly on relapse of mandibular anterior crowding. However the interest on maxillary anterior crowding and its relapse has been growing because of the greater conscious on smile esthetic among patients. Therefore, the purpose of this study was to compare the relapse of maxillary anterior crowding in cases presenting Angles Class I and Class II malocclusions. The experimental sample consisted of 70 patients divided into 3 groups. Group 1 comprised 30 patients (12 male; 18 female) at a mean initial age of 13.16 years, with Class I malocclusion, treated with all first premolars extraction. Group 2 comprised 20 patients (11 male; 9 female) at a mean initial age of 12.95 years, with Class II division 1 malocclusion, also treated with all first premolars extraction. Group 3 comprised 20 patients (10 male; 10 female) at a mean initial age of 13.09 years, with Class II division 1 malocclusion, treated with extraction of two maxillary first premolars. Dental casts measurements were obtained at three stages (pretreatment, posttreatment and postretention) and the variables assessed were Little Irregularity Index, maxillary arch length, intercanine, interpremolar and intermolar widths. The statistical analysis was performed by one-way ANOVA and Tukey tests if necessary (intragroup comparison) and by independent t-tests (intergroup comparison). As the results among the groups did not show statistically significant difference, the experimental sample was unified in order to inve stigate, using Pearson correlation coefficient and Multiple linear regression, if some studied variable would have influence the crowding in the three stages (IRLS1, IRLS2, IRLS3). The results showed that the maxillary crowding relapse (IRLS3-2) is influenced by the initial (IRLS1), and the teeth tend to return to their pretreatment position. The females presented more maxillary anterior crowding relapse than males.

Submitted by Erika Demachki (erikademachki@gmail.com) on 2015-02-13T16:22:17Z No. of bitstreams: 2 Dissertação - Karine Evangelista Martins Arruda - 2009.pdf: 8715038 bytes, checksum: d21da1c098fc0bfd5e300a4c0e32fdb8 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Erika Demachki (erikademachki@gmail.com) on 2015-02-13T16:23:07Z (GMT) No. of bitstreams: 2 Dissertação - Karine Evangelista Martins Arruda - 2009.pdf: 8715038 bytes, checksum: d21da1c098fc0bfd5e300a4c0e32fdb8 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2015-02-13T16:23:07Z (GMT). No. of bitstreams: 2 Dissertação - Karine Evangelista Martins Arruda - 2009.pdf: 8715038 bytes, checksum: d21da1c098fc0bfd5e300a4c0e32fdb8 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2009-01-16 / The effects of orthodontic treatment on periodontal structures have been studied in literature, especially regarding the integrity of alveolar bone and gingival health of the teeth to be displaced. The aim of this study was to evaluate the presence of alveolar defects (dehiscence and fenestrations) in patients with Class I and Class II division 1 malocclusions and in different facial types using cone beam computed tomography (CBCT). The sample comprised 159 tomography exams of patients with no previous orthodontic treatment, giving a total of 4319 teeth. The presence or absence of dehiscence and fenestration in the buccal and lingual surfaces was checked in axial and crosssectional views. The results showed that 155 patients (96.9%) presented some type of alveolar defect. The Class I malocclusion patients presented higher prevalence of dehiscences (35%) than those with Class II division 1 malocclusion. There was no statistically significant difference between the facial types. Lower incisors, lower canines and lower first premolars were respectively the teeth with more occurrences of alveolar defects. This study concluded that CBCT is indicated for patients who need extensive tooth movement and have unfavorable gingival biotype. / Os efeitos do tratamento ortodôntico nas estruturas periodontais tem sido objeto de estudo da literatura, principalmente quanto à integridade óssea e saúde gengival dos dentes a serem deslocados. O objetivo deste estudo foi avaliar a presença de defeitos alveolares (deiscências e fenestrações) em pacientes com maloclusão de Classe I e Classe II divisão 1 e em diferentes tipos faciais por meio de tomografia computadorizada volumétrica. A amostra foi composta de 159 exames tomográficos de pacientes indicados para tratamento ortodôntico, totalizando 4319 dentes avaliados. A presença ou ausência de deiscência e fenestração nas faces vestibular e lingual/palatina era observada em tomogramas axiais e transversais. Os resultados demonstraram que 155 pacientes (96,9%) apresentaram algum tipo de defeito alveolar. Os pacientes com maloclusão de Classe I apresentaram maior prevalência das deiscências (35%) em relação aos pacientes com maloclusão de Classe II divisão 1. Entre os tipos faciais não houve diferença estatisticamente significante. Incisivos inferiores, caninos inferiores e primeiros pré-molares inferiores foram respectivamente os dentes com maior ocorrência dos defeitos. Este estudo concluiu que a tomografia computadorizada volumétrica está indicada nos casos de pacientes que necessitem de movimento ortodôntico mais extenso e possuam biótipo gengival desfavorável.

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.