No description available.

RIPPLY2 is an essential part of the formation of somite patterning during embryogenesis and in establishment of rostro-caudal polarity. Here, we describe three individuals from two families with compound-heterozygous variants in RIPPLY2 (NM_001009994.2): c.238A > T, p.(Arg80*) and c.240-4 T > G, p.(?), in two 15 and 20-year-old sisters, and a homozygous nonsense variant, c.238A > T, p.(Arg80*), in an 8 year old boy. All patients had multiple vertebral body malformations in the cervical and thoracic region, small or absent rib involvement, myelopathies, and common clinical features of SCDO6 including scoliosis, mild facial asymmetry, spinal spasticity and hemivertebrae. The nonsense variant can be classified as likely pathogenic based on the ACMG criteria while the splice variants must be classified as a variant of unknown significance. With this report on two further families, we confirm RIPPLY2 as the gene for SCDO6 and broaden the phenotype by adding myelopathy with or without spinal canal stenosis and spinal spasticity to the symptom spectrum.

Les malformations artério-­‐veineuses cérébrales (MAVc) sont des pathologies vasculaires agressives présentant un risque hémorragique lourd de conséquence en terme de morbi-­‐mortalité. Les outils d’imagerie disponibles actuellement ne permettent de comprendre que difficilement leur angio-­‐ architecture. Nous avons développé dans notre travail deux outils d’imagerie permettant d’affiner la compréhension de l’anatomie des ces malformations : un algorithme de segmentation semi-­‐automatisé et un algorithme d’anamorphose sphérique convexe. Ces algorithmes ont été élaborés pour être utilisés sur les acquisitions d’angiographie rotationnelle 3D ; ils permettent de mieux visualiser la veine de drainage principale des MAVc, notamment d’identifier une sténose ou une ectasie focale sur cette veine, et également de déceler de façon plus fiable la présence d’un anévrysme intra-­‐nidal. Ces améliorations dans l’analyse de l’angio-­‐architecture des MAVc permettront vraisemblablement de réduire le risque thérapeutique pour ces malformations. En vue de tester le potentiel des agents anti-­‐angiogéniques pour le traitement des MAVc, nous avons élaboré un modèle porcin simplifié de MAVc consistant en une occlusion unilatérale d’artère carotide primitive par voie endovasculaire. La comparaison entre le volume de rete mirabile à J0 et à 3 mois et les valeurs obtenues pour un groupe témoin a montré une augmentation significative du volume du rete mirabile chez les porcs ayant eu l’occlusion carotidienne. D’autre part, une tendance nette à l’augmentation des taux de VEGF (vascular endothelial growth factor) à proximité du rete mirabile était observée dans le groupe occlusion. Enfin, des modifications anatomopathologiques proches de celles des MAVc humaines étaient visualisées sur les pièces autopsiques des rete mirabile dans le groupe occlusion. / Brain arteriovenous malformations (bAVMs) are aggressive vascular malformations presenting a haemorrhagic complication risk that may lead to severe consequences in terms of morbi-­‐mortality. Available imaging tools poorly help in understanding their angio-­‐architecture. We have developed two imaging tools improving our understanding of the anatomy of these malformations: a semi-­‐automated segmentation algorithm and a convex spherical anamorphosis algorithm. These algorithms have been elaborated for use on 3D rotational angiography acquisitions; they provide a better visualisation of the bAVMs’ main draining vein, especially for venous stenosis or for focal ectasia. They also help in depicting accurately intranidal aneurysms. These improvements in the analysis of the bAVMs’ angioarchitecure may help in reducing the therapeutic risk for these malformations. For a further testing of the potential of anti-­‐angiogenic agents for the treatment of bAVMs, we have elaborated a simplified swine AVM model consisting in the occlusion of a common carotid artery by endovascular means. The comparison between the volume of the rete mirabile at D0 and 3 months and those measured in a control group showed a significant increasing of the retia in the occlusion group. Moreover, a tendency was observed concerning an increase in VEGF (vascular endothelial growth factor) serum levels close to the rete mirabile in the occlusion group. Finally, pathological changes close to those seen in human bAVMs were observed on autopsy samples in the occlusion group.

Le cœur des vertébrés est un organe modulaire qui requiert le " patterning " complexe des champs morphogénétiques cardiogènes et la convergence coordonnée des diverses sous-populations de progéniteurs cardiogéniques. Au moins 7 facteurs de transcription de la famille T-box coopèrent au sein de ces nombreuses sous-populations de progéniteurs cardiogéniques afin de réguler la morphogenèse et l’agencement de multiples structures le long de l’ébauche cardiaque, ce qui explique que les mutations humaines de ces gènes engendrent diverses malformations congénitales cardiaques (MCCs). L’un de ces gènes T-box, Tbx5, dont l’haploinsuffisance génère le syndrome de Holt-Oram (SHO), intervient dans une grande variété de réseaux de régulation géniques (RRGs) qui orchestrent la morphogenèse des oreillettes, du ventricule gauche, de la valve mitrale, des septums inter-auriculaire et inter-ventriculaire, ainsi que du système de conduction cardiaque. La diversité des RRGs impliqués dans la formation de ces structures cardiaques suggère que Tbx5 détient une profusion de fonctions qui ne seront identifiables qu’en répertoriant ses activités moléculaires dans chaque lignée cardiaque examinée isolément. Afin d’aborder cette problématique, une ablation génétique de Tbx5 dans l’endocarde a été réalisée. Cette expérience a démontré le rôle crucial de Tbx5 dans la survie des cellules endocardiques bordant le septum primum et des cardiomyocytes au sein de cette structure embryonnaire qui contribuera à la morphogenèse du septum inter-auriculaire. En outre, cette étude a révélé l’existence d’une communication croisée entre la sous-population de cellules endocardiques Tbx5+ et le myocarde au niveau du septum primum, afin d’assurer la survie des cardiomyocytes, et ultimement de garantir la maturation du septum inter-auriculaire. Nos résultats confirment aussi l’importance de l’interdépendance génétique (Tbx5 et Gata4 ainsi que Tbx5 et Nos3) entre différents loci dans la morphogenèse de la cloison inter-auriculaire, et particulièrement de l’influence que peut avoir l’environnement sur la pénétrance et l’expressivité des communications inter-auriculaires (CIAs) dans le SHO. En outre, puisque les fonctions d’un gène dépendent ordinairement des différents isoformes qu’il peut générer, une deuxième étude a focalisé davantage sur l’aspect transcriptionnel de Tbx5. Cette approche a mené à la découverte de 6 transcrits alternatifs exhibant des fonctions à la fois communes et divergentes. La caractérisation de 2 de ces isoformes a révélé le rôle de l’isoforme long (Tbx5_v1) dans la régulation de la croissance des cardiomyocytes durant la cardiogénèse, tandis que l’isoforme court (Tbx5_v2), préférentiellement exprimé dans le cœur mature, réprime la croissance cellulaire. Il est donc entièrement concevable que les mutations de TBX5 entraînant une troncation de la région C-terminale accroissent la concentration d’une protéine mutée qui, à l’instar de Tbx5_v2, interfère avec la croissance de certaines structures cardiaques. En revanche, la divergence de fonctions de ces isoformes, caractérisée par les disparités de localisation subcellulaire et de d’interaction avec d’autres cofacteurs cardiaques, suggère que les mutations affectant davantage un isoforme favoriseraient l’émergence d’un type particulier de MCC. Finalement, un dernier objectif était d’identifier le ou les mécanisme(s) moléculaire(s) par le(s)quel(s) Tbx5 régule son principal gène cible, Nppa, et d’en extraire les indices qui éclairciraient sa fonction transcriptionnelle. Cet objectif nécessitait dans un premier lieu d’identifier les différents modules cis-régulateurs (MCRs) coordonnant la régulation transcriptionnelle de Nppa et Nppb, deux gènes natriurétiques dont l’organisation en tandem et le profil d’expression durant la cardiogénèse sont conservés dans la majorité des vertébrés. L’approche d’empreinte phylogénétique employée pour scanner le locus Nppb/Nppa a permis d’identifier trois MCRs conservés entre diverses espèces de mammifères, dont un (US3) est spécifique aux euthériens. Cette étude a corroboré que la régulation de l’expression du tandem génique Nppb/Nppa requérait l’activité transcriptionnelle d’enhancers en complément aux promoteurs de Nppa et Nppb. La concordance quasiment parfaite entre les profils d’expression de Tbx5 et de ces deux gènes natriurétiques chez les mammifères, suggère que le gradient d’expression ventriculaire de Tbx5 est interprété par le recrutement de ce facteur au niveau des différents enhancers identifiés. En somme, les études présentées dans cette thèse ont permis de clarifier la profusion de fonctions cardiaques que possède Tbx5. Certaines de ces fonctions émanent de l’épissage alternatif de Tbx5, qui favorise la synthèse d’isoformes dotés de propriétés spécifiques. Les diverses interactions combinatoires entre ces isoformes et d’autres facteurs cardiaques au sein des diverses sous-populations de progéniteurs cardiogènes contribuent à l’émergence de RRGs cardiaques divergents. / The vertebrate heart is a modular organ, which requires the complex patterning of the morphogenetic heart fields and the coordinated convergence of the diverse subpopulations of cardiogenic progenitors. At least 7 transcription factors of the T-box family cooperate within these numerous subpopulations of cardiogenic progenitors to regulate the morphogenesis and the layout of multiple structures along the primordial heart tube, which explains that the human mutations of these genes induce various congenital heart defects (CHDs). One of these T-box genes, Tbx5, whose haploinsufficiency generates the Holt-Oram syndrome (HOS), intervenes in a wide variety of gene regulatory networks (GRNs) that orchestrate the morphogenesis of the atria, the left ventricle, the mitral valve, the inter-atrial and inter-ventricular septa, as well as the cardiac conduction system. The diversity of GRNs involved in the formation of these cardiac structures suggests that Tbx5 holds a profusion of functions which will be identifiable only by indexing its molecular activities in each separately examined cardiac lineage. To address this problem, a conditional knockout of Tbx5 in the endocardium was generated. This experiment demonstrated a crucial role of Tbx5 in the survival of the endocardial cells lining the septum primum and the cardiomyocytes within this embryonic structure, which will contribute to the morphogenesis of the inter-atrial septum. Moreover, this study revealed a crosstalk between the Tbx5-positive endocardial cells subpopulation and the myocardium at the level of the septum primum to ensure the survival of cardiomyocytes, and ultimately to guarantee the maturation of the inter-atrial septum. Our results also confirmed the importance of genetic interdependence (Tbx5 and Gata4 as well as Tbx5 and Nos3) between different loci in the morphogenesis of the inter-atrial septum, and particularly the influence that the environment can have on the penetrance and the expressivity of atrial septal defects (ASDs) in the HOS. Besides, since the functions of a gene usually depend on the different isoforms it can generate, a second study focused more on the transcriptional aspect of Tbx5. This approach led to the discovery of 6 alternative transcripts exhibiting both common and specific functions. The characterization of 2 of these isoforms revealed the role of the long isoform (Tbx5_v1) in the regulation of cardiomyocytes growth during cardiogenesis, whereas the short isoform (Tbx5_v2), preferentially expressed in the mature heart, represses cell growth. It is thus entirely conceivable that TBX5 mutations leading to a C-terminal truncation increase the concentration of a mutated protein, which, like Tbx5_v2, interferes with the growth of certain cardiac structures. On the other hand, the divergence of functions of these isoforms, characterized by the disparities of subcellular localization and interaction with other cardiac cofactors, suggests that mutations affecting more one isoform would favor the emergence of a particular type of CHD. Finally, a last objective was to identify one or several molecular mechanism(s) by which Tbx5 regulates its main target gene, Nppa, and to extract clues that might clarify its transcriptional function. This objective required in a first place to identify the various cis-regulatory modules (CRMs) coordinating the transcriptional regulation of Nppa and Nppb, two natriuretic genes whose tandem organization and expression pattern during cardiogenesis are preserved in most vertebrates. The phylogenetic footprint approach employed to scan the Nppb/Nppa locus allowed the identification of three CRMs evolutionary conserved between different mammals species, one of which (US3) is specific to eutherians. This study confirmed that the regulation of the tandem genes Nppb/Nppa required the transcriptional activity of enhancers in complement to Nppa and Nppb promoters. The almost perfect concordance between the expression profiles of Tbx5 and these two natriuretic genes in mammals, suggests that the ventricular expression gradient of Tbx5 is interpreted by the recruitment of this factor to the identified enhancers. Altogether, the studies presented in this thesis allowed clarifying the profusion of Tbx5 cardiac functions. Some of these functions emanate from the alternative splicing of Tbx5, which favors the synthesis of isoforms endowed with specific properties. The diverse combinatorial interactions between these isoforms and other cardiac factors within the various cardiogenic progenitor subpopulations contribute to the emergence of distinct cardiac RRGs.

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

Introdução: A maioria dos fetos com lesão pulmonar congênita (LPC) são assintomáticos e apresentam baixa morbidade ao nascimento. No entanto, alguns neonatos apresentam desconforto respiratório e necessitam receber de cuidados especiais neste período. Decidir quais casos com LPC precisam nascer em um centro de referência é um desafio. Objetivo: O objetivo deste estudo foi predizer a morbidade neonatal em fetos com LCP sem hidropisia avaliados pela ultrassonografia tridimensional (US3D). Método: Estudo observacional, entre janeiro de 2005 e janeiro de 2016, com fetos com LPC e sem hidropisia. Os volumes pulmonares foram mensurados pela US3D, técnica VOCAL, em dois períodos: entre 20 e 28 semanas (1o momento) e entre 29 e 34 semanas (2o momento). A variação intra e inter-operador foi analisada para os volumes pulmonares. As relações volumétricas testadas foram: volume pulmonar observado / esperado (VPTo/e); volume da lesão pulmonar / circunferência cefálica (LVR) e volume da lesão / volume pulmonar observado (VL/VPTo). As relações volumétricas foram usadas na predição da morbidade neonatal (admissão em unidade de terapia intensiva neonatal (UTI), necessidade de intubação (IOT); necessidade de cirurgia no período neonatal por sintomatologia respiratória). Regressão logística múltipla e curva ROC foram aplicadas para determinar a acurácia na predição dos resultados. Resultados: Dos 45 fetos não hidrópicos com LPC incluídos no estudo, 18 (40%) foram admitidos na UTI, 14 (31,1%) necessitaram de IOT, e sete (15,6%) cirurgia neonatal. A variação intra e inter-operador para os volumes pulmonares apresentou boa reprodutibilidade e não houve diferença estatística (p > 0,05). No 1o momento (IG: 20 - 28 semanas) observou-se que todas as relações volumétricas (1oVPTo/e, 1oLVR e 1oVL/VPTo) foram preditoras para admissão na UTI e necessidade de IOT. No 2o momento (IG: 29 - 34 semanas), apenas o 2oVPTo/e, e, 2oVL/VPTo foram preditores para IOT. Nenhuma das razões volumétricas (VPTo/e, LVR e VL/VPTo) foram preditoras para a cirurgia neonatal. No 1º momento, o melhor preditor para UTI foi 1º VPTo/e (ASC 0,86; p < 0,001) e para IOT foi 1º VL/VPTo (ASC 0,94; p < 0,001). Os cut-off escolhidos para a admissão na UTI foi 1º VPTo/e<0,53 (s:91,7%; e:70,8%; a:77,8%); e para IOT foi 1º VL/VPTo > 1,18 (s:91,7%; e:62,5%, a:72%). Para o 2o momento, a melhor relação volumétrica preditora para admissão na UTI foi 2º VL/VPTo (ASC 0,92; p < 0,001) e para necessidade de IOT foi 2º VPTo/e (ASC 0,87; p < 0,001). O cutoff escolhido foi 2ºVL/VPTo > 0,42 para a admissão na UTI (s:94,1%; e:82,3%; a:88%); e 2ºVPTo/e < 0,50 para IOT (s:92,9%; e:75%; a:82,3%). Conclusão: As relações volumétricas pulmonares mensuradas pela US3D podem predizer as morbidades neonatais em fetos não hidrópicos com LPC. O VPTo/e e VL/VPTo foram os melhores preditores da morbidade neonatal. Esses dados podem auxiliar no aconselhamento aos pais e na escolha do local mais adequado para o parto / Introduction: Most fetuses with congenital lung malformation (CLM) are asymptomatic and have low morbidity. However, some newborns present respiratory discomfort and need special care. Therefore, decide which cases need to be delivered in a referring center is challenging. Objectives: The purpose of this study was to predict neonatal morbidity in non-hydropic fetuses with CLM assessed by threedimensional ultrasonography (3DUS). Method: Observational study, between January 2005 and January 2016, involving non-hydropic fetuses with CLM. The fetal lung volumes were assessed by 3DUS, by VOCAL technique, in two moments: between 20 and 28 weeks (1st moment) and between 29 and 34 weeks (2nd moment). Intra- and inter-operator variabilities were also evaluated in estimating fetal lung volumes by 3DUS. The following volumetric ratios were assessed: observed / expected normal fetal lung volume (oeTLV), fetal lung lesion volume ratio (LVR), and lesion-to-lung volume ratio (LLV). The lung volumetric ratios were used for the prediction of neonatal morbidity (admission to NICU, need of orotracheal intubation (OTI), or need for lung surgery in neonatal period due to respiratory symptoms). Multivariate regression analyses and receiver operator characteristic curve (ROC) were applied to determine the best volumetric ratio to predict the neonatal morbidity. Results: Forty-five non-hydropic fetuses with CLM were selected for the study. Eighteen (40%) were admitted to the NICU, 14 (31.1%) needed intubation and seven (15.6%) needed neonatal surgery. The variation intra and inter-operator for lung volumes showed good reproducibility and no statistical difference (p>0.05). In the 1st moment (GA: 20 - 28 weeks), all 3DUS ratios (1st oeTLV, 1st LVR, and 1st LLV) demonstrated strong prediction for NICU admission and need of intubation. In the 2nd moment (GA: 29 - 34 weeks), only 2nd oeTLV and 2nd LLV correlated with need of intubation. None of the volumetric ratios (oeTLV, LVR and LLV) were predictive of neonatal surgery. In the 1st moment the best volume ratio for the prediction of NICU admission was 1st oeTLV (AUC 0.86, p < 0.001) and for the need of intubation was 1st LLV (AUC 0.94, p < 0.001). The cut-off chosen for NICU admission was 1st oeTLV < 0.53 (sensitivity 91.7%, specificity 70.8%, accuracy 77.8%); and for the prediction of the need of intubation was 1st LLV > 1.18 (sensitivity 91.7%, specificity 62.5%, accuracy 72%). In the 2nd moment, the best volume ratio for the prediction of NICU admission was 2nd LLV (AUC 0.92, p < 0.001) and the prediction of the need of intubation was 2nd oeTLV (AUC 0.87, p < 0.001). The cut-off chosen for the prediction of NICU admission was 2ndLLV > 0.42 (sensitivity 94.1%, specificity 82.3%, accuracy 88%); and for the prediction of the need of intubation was 2nd oeTLV < 0.50 (sensitivity 92.9%, specificity 75%, accuracy 82.3%). Conclusion: Lung volume ratio measured by 3DUS can predict neonatal morbidity in nonhydropic fetuses with CLM. The oeTLV and LLV were the best predictors of neonatal morbidity. These findings can be useful in counseling parents and in choosing the most appropriate place for delivery

Introdução: A maioria dos fetos com lesão pulmonar congênita (LPC) são assintomáticos e apresentam baixa morbidade ao nascimento. No entanto, alguns neonatos apresentam desconforto respiratório e necessitam receber de cuidados especiais neste período. Decidir quais casos com LPC precisam nascer em um centro de referência é um desafio. Objetivo: O objetivo deste estudo foi predizer a morbidade neonatal em fetos com LCP sem hidropisia avaliados pela ultrassonografia tridimensional (US3D). Método: Estudo observacional, entre janeiro de 2005 e janeiro de 2016, com fetos com LPC e sem hidropisia. Os volumes pulmonares foram mensurados pela US3D, técnica VOCAL, em dois períodos: entre 20 e 28 semanas (1o momento) e entre 29 e 34 semanas (2o momento). A variação intra e inter-operador foi analisada para os volumes pulmonares. As relações volumétricas testadas foram: volume pulmonar observado / esperado (VPTo/e); volume da lesão pulmonar / circunferência cefálica (LVR) e volume da lesão / volume pulmonar observado (VL/VPTo). As relações volumétricas foram usadas na predição da morbidade neonatal (admissão em unidade de terapia intensiva neonatal (UTI), necessidade de intubação (IOT); necessidade de cirurgia no período neonatal por sintomatologia respiratória). Regressão logística múltipla e curva ROC foram aplicadas para determinar a acurácia na predição dos resultados. Resultados: Dos 45 fetos não hidrópicos com LPC incluídos no estudo, 18 (40%) foram admitidos na UTI, 14 (31,1%) necessitaram de IOT, e sete (15,6%) cirurgia neonatal. A variação intra e inter-operador para os volumes pulmonares apresentou boa reprodutibilidade e não houve diferença estatística (p > 0,05). No 1o momento (IG: 20 - 28 semanas) observou-se que todas as relações volumétricas (1oVPTo/e, 1oLVR e 1oVL/VPTo) foram preditoras para admissão na UTI e necessidade de IOT. No 2o momento (IG: 29 - 34 semanas), apenas o 2oVPTo/e, e, 2oVL/VPTo foram preditores para IOT. Nenhuma das razões volumétricas (VPTo/e, LVR e VL/VPTo) foram preditoras para a cirurgia neonatal. No 1º momento, o melhor preditor para UTI foi 1º VPTo/e (ASC 0,86; p < 0,001) e para IOT foi 1º VL/VPTo (ASC 0,94; p < 0,001). Os cut-off escolhidos para a admissão na UTI foi 1º VPTo/e<0,53 (s:91,7%; e:70,8%; a:77,8%); e para IOT foi 1º VL/VPTo > 1,18 (s:91,7%; e:62,5%, a:72%). Para o 2o momento, a melhor relação volumétrica preditora para admissão na UTI foi 2º VL/VPTo (ASC 0,92; p < 0,001) e para necessidade de IOT foi 2º VPTo/e (ASC 0,87; p < 0,001). O cutoff escolhido foi 2ºVL/VPTo > 0,42 para a admissão na UTI (s:94,1%; e:82,3%; a:88%); e 2ºVPTo/e < 0,50 para IOT (s:92,9%; e:75%; a:82,3%). Conclusão: As relações volumétricas pulmonares mensuradas pela US3D podem predizer as morbidades neonatais em fetos não hidrópicos com LPC. O VPTo/e e VL/VPTo foram os melhores preditores da morbidade neonatal. Esses dados podem auxiliar no aconselhamento aos pais e na escolha do local mais adequado para o parto / Introduction: Most fetuses with congenital lung malformation (CLM) are asymptomatic and have low morbidity. However, some newborns present respiratory discomfort and need special care. Therefore, decide which cases need to be delivered in a referring center is challenging. Objectives: The purpose of this study was to predict neonatal morbidity in non-hydropic fetuses with CLM assessed by threedimensional ultrasonography (3DUS). Method: Observational study, between January 2005 and January 2016, involving non-hydropic fetuses with CLM. The fetal lung volumes were assessed by 3DUS, by VOCAL technique, in two moments: between 20 and 28 weeks (1st moment) and between 29 and 34 weeks (2nd moment). Intra- and inter-operator variabilities were also evaluated in estimating fetal lung volumes by 3DUS. The following volumetric ratios were assessed: observed / expected normal fetal lung volume (oeTLV), fetal lung lesion volume ratio (LVR), and lesion-to-lung volume ratio (LLV). The lung volumetric ratios were used for the prediction of neonatal morbidity (admission to NICU, need of orotracheal intubation (OTI), or need for lung surgery in neonatal period due to respiratory symptoms). Multivariate regression analyses and receiver operator characteristic curve (ROC) were applied to determine the best volumetric ratio to predict the neonatal morbidity. Results: Forty-five non-hydropic fetuses with CLM were selected for the study. Eighteen (40%) were admitted to the NICU, 14 (31.1%) needed intubation and seven (15.6%) needed neonatal surgery. The variation intra and inter-operator for lung volumes showed good reproducibility and no statistical difference (p>0.05). In the 1st moment (GA: 20 - 28 weeks), all 3DUS ratios (1st oeTLV, 1st LVR, and 1st LLV) demonstrated strong prediction for NICU admission and need of intubation. In the 2nd moment (GA: 29 - 34 weeks), only 2nd oeTLV and 2nd LLV correlated with need of intubation. None of the volumetric ratios (oeTLV, LVR and LLV) were predictive of neonatal surgery. In the 1st moment the best volume ratio for the prediction of NICU admission was 1st oeTLV (AUC 0.86, p < 0.001) and for the need of intubation was 1st LLV (AUC 0.94, p < 0.001). The cut-off chosen for NICU admission was 1st oeTLV < 0.53 (sensitivity 91.7%, specificity 70.8%, accuracy 77.8%); and for the prediction of the need of intubation was 1st LLV > 1.18 (sensitivity 91.7%, specificity 62.5%, accuracy 72%). In the 2nd moment, the best volume ratio for the prediction of NICU admission was 2nd LLV (AUC 0.92, p < 0.001) and the prediction of the need of intubation was 2nd oeTLV (AUC 0.87, p < 0.001). The cut-off chosen for the prediction of NICU admission was 2ndLLV > 0.42 (sensitivity 94.1%, specificity 82.3%, accuracy 88%); and for the prediction of the need of intubation was 2nd oeTLV < 0.50 (sensitivity 92.9%, specificity 75%, accuracy 82.3%). Conclusion: Lung volume ratio measured by 3DUS can predict neonatal morbidity in nonhydropic fetuses with CLM. The oeTLV and LLV were the best predictors of neonatal morbidity. These findings can be useful in counseling parents and in choosing the most appropriate place for delivery

Le cœur des vertébrés est un organe modulaire qui requiert le " patterning " complexe des champs morphogénétiques cardiogènes et la convergence coordonnée des diverses sous-populations de progéniteurs cardiogéniques. Au moins 7 facteurs de transcription de la famille T-box coopèrent au sein de ces nombreuses sous-populations de progéniteurs cardiogéniques afin de réguler la morphogenèse et l’agencement de multiples structures le long de l’ébauche cardiaque, ce qui explique que les mutations humaines de ces gènes engendrent diverses malformations congénitales cardiaques (MCCs). L’un de ces gènes T-box, Tbx5, dont l’haploinsuffisance génère le syndrome de Holt-Oram (SHO), intervient dans une grande variété de réseaux de régulation géniques (RRGs) qui orchestrent la morphogenèse des oreillettes, du ventricule gauche, de la valve mitrale, des septums inter-auriculaire et inter-ventriculaire, ainsi que du système de conduction cardiaque. La diversité des RRGs impliqués dans la formation de ces structures cardiaques suggère que Tbx5 détient une profusion de fonctions qui ne seront identifiables qu’en répertoriant ses activités moléculaires dans chaque lignée cardiaque examinée isolément. Afin d’aborder cette problématique, une ablation génétique de Tbx5 dans l’endocarde a été réalisée. Cette expérience a démontré le rôle crucial de Tbx5 dans la survie des cellules endocardiques bordant le septum primum et des cardiomyocytes au sein de cette structure embryonnaire qui contribuera à la morphogenèse du septum inter-auriculaire. En outre, cette étude a révélé l’existence d’une communication croisée entre la sous-population de cellules endocardiques Tbx5+ et le myocarde au niveau du septum primum, afin d’assurer la survie des cardiomyocytes, et ultimement de garantir la maturation du septum inter-auriculaire. Nos résultats confirment aussi l’importance de l’interdépendance génétique (Tbx5 et Gata4 ainsi que Tbx5 et Nos3) entre différents loci dans la morphogenèse de la cloison inter-auriculaire, et particulièrement de l’influence que peut avoir l’environnement sur la pénétrance et l’expressivité des communications inter-auriculaires (CIAs) dans le SHO. En outre, puisque les fonctions d’un gène dépendent ordinairement des différents isoformes qu’il peut générer, une deuxième étude a focalisé davantage sur l’aspect transcriptionnel de Tbx5. Cette approche a mené à la découverte de 6 transcrits alternatifs exhibant des fonctions à la fois communes et divergentes. La caractérisation de 2 de ces isoformes a révélé le rôle de l’isoforme long (Tbx5_v1) dans la régulation de la croissance des cardiomyocytes durant la cardiogénèse, tandis que l’isoforme court (Tbx5_v2), préférentiellement exprimé dans le cœur mature, réprime la croissance cellulaire. Il est donc entièrement concevable que les mutations de TBX5 entraînant une troncation de la région C-terminale accroissent la concentration d’une protéine mutée qui, à l’instar de Tbx5_v2, interfère avec la croissance de certaines structures cardiaques. En revanche, la divergence de fonctions de ces isoformes, caractérisée par les disparités de localisation subcellulaire et de d’interaction avec d’autres cofacteurs cardiaques, suggère que les mutations affectant davantage un isoforme favoriseraient l’émergence d’un type particulier de MCC. Finalement, un dernier objectif était d’identifier le ou les mécanisme(s) moléculaire(s) par le(s)quel(s) Tbx5 régule son principal gène cible, Nppa, et d’en extraire les indices qui éclairciraient sa fonction transcriptionnelle. Cet objectif nécessitait dans un premier lieu d’identifier les différents modules cis-régulateurs (MCRs) coordonnant la régulation transcriptionnelle de Nppa et Nppb, deux gènes natriurétiques dont l’organisation en tandem et le profil d’expression durant la cardiogénèse sont conservés dans la majorité des vertébrés. L’approche d’empreinte phylogénétique employée pour scanner le locus Nppb/Nppa a permis d’identifier trois MCRs conservés entre diverses espèces de mammifères, dont un (US3) est spécifique aux euthériens. Cette étude a corroboré que la régulation de l’expression du tandem génique Nppb/Nppa requérait l’activité transcriptionnelle d’enhancers en complément aux promoteurs de Nppa et Nppb. La concordance quasiment parfaite entre les profils d’expression de Tbx5 et de ces deux gènes natriurétiques chez les mammifères, suggère que le gradient d’expression ventriculaire de Tbx5 est interprété par le recrutement de ce facteur au niveau des différents enhancers identifiés. En somme, les études présentées dans cette thèse ont permis de clarifier la profusion de fonctions cardiaques que possède Tbx5. Certaines de ces fonctions émanent de l’épissage alternatif de Tbx5, qui favorise la synthèse d’isoformes dotés de propriétés spécifiques. Les diverses interactions combinatoires entre ces isoformes et d’autres facteurs cardiaques au sein des diverses sous-populations de progéniteurs cardiogènes contribuent à l’émergence de RRGs cardiaques divergents. / The vertebrate heart is a modular organ, which requires the complex patterning of the morphogenetic heart fields and the coordinated convergence of the diverse subpopulations of cardiogenic progenitors. At least 7 transcription factors of the T-box family cooperate within these numerous subpopulations of cardiogenic progenitors to regulate the morphogenesis and the layout of multiple structures along the primordial heart tube, which explains that the human mutations of these genes induce various congenital heart defects (CHDs). One of these T-box genes, Tbx5, whose haploinsufficiency generates the Holt-Oram syndrome (HOS), intervenes in a wide variety of gene regulatory networks (GRNs) that orchestrate the morphogenesis of the atria, the left ventricle, the mitral valve, the inter-atrial and inter-ventricular septa, as well as the cardiac conduction system. The diversity of GRNs involved in the formation of these cardiac structures suggests that Tbx5 holds a profusion of functions which will be identifiable only by indexing its molecular activities in each separately examined cardiac lineage. To address this problem, a conditional knockout of Tbx5 in the endocardium was generated. This experiment demonstrated a crucial role of Tbx5 in the survival of the endocardial cells lining the septum primum and the cardiomyocytes within this embryonic structure, which will contribute to the morphogenesis of the inter-atrial septum. Moreover, this study revealed a crosstalk between the Tbx5-positive endocardial cells subpopulation and the myocardium at the level of the septum primum to ensure the survival of cardiomyocytes, and ultimately to guarantee the maturation of the inter-atrial septum. Our results also confirmed the importance of genetic interdependence (Tbx5 and Gata4 as well as Tbx5 and Nos3) between different loci in the morphogenesis of the inter-atrial septum, and particularly the influence that the environment can have on the penetrance and the expressivity of atrial septal defects (ASDs) in the HOS. Besides, since the functions of a gene usually depend on the different isoforms it can generate, a second study focused more on the transcriptional aspect of Tbx5. This approach led to the discovery of 6 alternative transcripts exhibiting both common and specific functions. The characterization of 2 of these isoforms revealed the role of the long isoform (Tbx5_v1) in the regulation of cardiomyocytes growth during cardiogenesis, whereas the short isoform (Tbx5_v2), preferentially expressed in the mature heart, represses cell growth. It is thus entirely conceivable that TBX5 mutations leading to a C-terminal truncation increase the concentration of a mutated protein, which, like Tbx5_v2, interferes with the growth of certain cardiac structures. On the other hand, the divergence of functions of these isoforms, characterized by the disparities of subcellular localization and interaction with other cardiac cofactors, suggests that mutations affecting more one isoform would favor the emergence of a particular type of CHD. Finally, a last objective was to identify one or several molecular mechanism(s) by which Tbx5 regulates its main target gene, Nppa, and to extract clues that might clarify its transcriptional function. This objective required in a first place to identify the various cis-regulatory modules (CRMs) coordinating the transcriptional regulation of Nppa and Nppb, two natriuretic genes whose tandem organization and expression pattern during cardiogenesis are preserved in most vertebrates. The phylogenetic footprint approach employed to scan the Nppb/Nppa locus allowed the identification of three CRMs evolutionary conserved between different mammals species, one of which (US3) is specific to eutherians. This study confirmed that the regulation of the tandem genes Nppb/Nppa required the transcriptional activity of enhancers in complement to Nppa and Nppb promoters. The almost perfect concordance between the expression profiles of Tbx5 and these two natriuretic genes in mammals, suggests that the ventricular expression gradient of Tbx5 is interpreted by the recruitment of this factor to the identified enhancers. Altogether, the studies presented in this thesis allowed clarifying the profusion of Tbx5 cardiac functions. Some of these functions emanate from the alternative splicing of Tbx5, which favors the synthesis of isoforms endowed with specific properties. The diverse combinatorial interactions between these isoforms and other cardiac factors within the various cardiogenic progenitor subpopulations contribute to the emergence of distinct cardiac RRGs.

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

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-09-04T23:45:22Z No. of bitstreams: 1 JOSÉ RÔMULO SOARES DOS SANTOS - TESE PPGMV 2012..pdf: 499950 bytes, checksum: a58df169790a0820def666327bad8f42 (MD5) / Made available in DSpace on 2018-09-04T23:45:22Z (GMT). No. of bitstreams: 1 JOSÉ RÔMULO SOARES DOS SANTOS - TESE PPGMV 2012..pdf: 499950 bytes, checksum: a58df169790a0820def666327bad8f42 (MD5) Previous issue date: 2012-12-20 / Esta tese inclui uma revisão de literatura e dois artigos. O primeiro capítulo é uma revisão que abrange princípios gerais da teratologia, a epidemiologia, o diagnóstico, a clínica e a patologia das malformações em pequenos ruminantes. No artigo que corresponde ao segundo capítulo, foi estudado a teratogenicidade de Mimosa tenuiflora. Quinze ovelhas, distribuídas em dois grupos foram introduzidas em área invadida pela planta. O Grupo 1, com seis ovelhas prenhes, foi introduzido na área experimental 20 dias após o acasalamento. O Grupo 2, formado por nove ovelhas não prenhes e um carneiro, foi introduzido na área experimental no início do experimento. A cada 15 dias eram realizados exames ultrassonográficos para acompanhamento da gestação. No Grupo 1, três ovelhas abortaram, cada uma um feto sem malformações. Outra ovelha pariu dois cordeiros, um com hiperflexão na articulação interfalangeana proximal no membro torácico direito e outro sem malformações. Outra ovelha pariu um cordeiro com hiperflexão dos dois membros pélvicos na região da articulação tarsometatársica. No grupo 2, uma ovelha abortou um feto sem malformações e cinco pariram cordeiros normais. Três das ovelhas desse grupo não emprenharam durante todo o período experimental, mostrando retornos repetidos ao cio, sugerindo perda embrionária. Concluiu-se que M. tenuiflora, além de causar malformações causa, também, mortalidade embrionária e abortos em ovelhas. No terceiro capitulo, o artigo relata os achados clínicos e patológicos de um caprino com lisencefalia e hipoplasia cerebelar. No exame físico, esse caprino de 30 dias, apresentava incoordenação e incapacidade de ficar em pé, decúbito esternal permanente, ataxia, ausência do reflexo de ameaça, tremores de intenção e nistagmo. Após 11 dias de internamento o caprino foi eutanasiado e necropsiado. Na necropsia, o cérebro não apresentava giros e sulcos e o cerebelo estava reduzido de tamanho. Histologicamente, em todo o córtex cerebral, a substância cinzenta estava mais espessa e a substância branca mais fina que o normal. Os neurônios estavam distribuídos de forma aleatória na substância cinzenta. No cerebelo, as camadas estavam desorganizadas, com localização heterotópica das células. Os achados macroscópicos e histológicos são característicos de lisencefalia e hipoplasia cerebelar. Lisencefalia é uma doença rara na medicina veterinária e não tinha sido descrita em caprinos. / This thesis includes a review and two papers. The first chapter is a review about general principles of teratology and epidemiology, diagnosis, clinical signs and pathology of malformations in small ruminants. The second chapter is a paper that studied the teratogenicity of Mimosa tenuiflora. Fifteen sheep, divided into two groups, were introduced into an area invaded by the plant. Group 1 consisted of six pregnant ewes that were introduced into the experimental area 20 days after mating. Group 2 consisted of nine non pregnant sheep and a ram introduced into the area at the start of the experiment. Every 15 days each sheep was examined by ultrasound to control pregnancy. In Group 1, three sheep aborted single fetuses without malformations. One sheep delivered two lambs, one with hyperflexion of the proximal inter-phalangeal joint of the right forelimb and another without malformations. Another sheep delivered a lamb with a hyperflexion of both hindlimbs in the region of the tarsal-metatarsal joint. Only one sheep delivered a normal lamb. In Group 2, one sheep aborted a fetus without malformations and five delivered normal lambs. Three sheep of this group returned to estrus repeatedly and did not get pregnant during the mating period, suggesting embryonic loss. It is concluded that M. tenuiflora cause malformations, embryonic mortality and abortion in sheep. In the third chapter, the paper relates a case of lissencephaly and cerebellar hypoplasia in a goat. The goat presented sternal recumbence, absent menace response, intention tremors, ataxia, and nystagmus. It was euthanized and necropsied after been hospitalized during eleven days. At necropsy, the surface of the brain was smooth, cerebral sulci and gyri were absent, and the cerebellum was reduced in size. Histologically, in all cerebral cortex, the grey matter was thicker and the white matter was thinner than normal. The neurons were arranged randomly in the grey matter. In the cerebellum, the layers were disorganized and there was heterotopy of the cells. The histologic and gross lesions are characteristic of lissencephaly associated with cerebellar hypoplasia. Lissencephaly is a rare disease in veterinary medicine and had not been reported previously in goats.