Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2017-03-07T18:43:04Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) natalia_avila_soares.pdf: 1056490 bytes, checksum: 869e513c0faa0977b352060ebd8f23f9 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2017-03-30T15:05:44Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) natalia_avila_soares.pdf: 1056490 bytes, checksum: 869e513c0faa0977b352060ebd8f23f9 (MD5) / Made available in DSpace on 2017-03-30T15:05:44Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) natalia_avila_soares.pdf: 1056490 bytes, checksum: 869e513c0faa0977b352060ebd8f23f9 (MD5) Previous issue date: 2016 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Objetivou-se com esse trabalho avaliar os efeitos da inclus?o de n?veis do farelo de crambe (Crambe abyssinica Hoechst), no perfil fermentativo e valor nutricional da silagem de cana-de-a??car avaliados em diferentes tempos de abertura dos silos. O experimento foi conduzido na Fazenda Experimental do Moura, pertencente ? Universidade Federal dos Vales do Jequitinhonha e Mucuri (UFVJM), localizada no Munic?pio de Curvelo, MG e as an?lises laboratoriais forma realizadas no Laborat?rio de Nutri??o Animal do Departamento de Zootecnia da UFVJM, Campus Diamantina, MG. Foi adotado um delineamento inteiramente casualizado em esquema fatorial 4 x 4, sendo quatro n?veis de adi??o do farelo de crambe (FC: 0; 5, 10 e 20%, com base na mat?ria natural) e quatro tempos de abertura dos silos (10; 20; 30; 60 dias ap?s a confec??o das silagens),com quatro repeti??es. Para a avalia??o da composi??o bromatol?gica usou-se: mat?ria seca (MS); mat?ria org?nica (MO), mat?ria mineral (MM), prote?na bruta (PB), extrato et?reo (EE), fibra em detergente neutro corrigida para cinzas e prote?na (FDNcp), fibra em detergente ?cido (FDA), carboidratos totais (CT), carboidratos n?o fibrosos (CNF) e nutrientes digest?veis totais calculados (NDTcalculado). Para o perfil fermentativo foram avaliados os valores da atividade de ?gua (Aw), potencial hidrogeni?nico (pH), condutividade el?trica (CE), carboidratos sol?veis (CHOs) e nitrog?nio amoniacal (N-NH3). Os dados foram submetidos ? an?lise de regress?o (P>0,05). Para vari?vel EE, foi observado efeito de dose e tempo (P>0,05). Para a intera??o dos fatores (n?veis de inclus?o do FC x tempo de abertura) observou-se efeito para MS, MM, PB, MO, FDNcp, FDA, CT, CNF, NDT calculado, CE, AW, CHOs, pH e N-NH3. A adi??o do farelo de crambe na ensilagem de cana-de-a??car promoveu melhorias na composi??o bromatol?gica, uma vez que houve eleva??o nos teores de MS, PB, CNF, al?m da redu??o nos componentes fibrosos (FDNcp e FDA), proporcionando assim um alimento de melhor qualidade. As altera??es promovidas pela adi??o do FC at? os 20% de inclus?o na ensilagem de cana n?o comprometeram o perfil fermentativo da massa ensilada. A inclus?o do FC ? indicada at? o n?vel de 10% (com base na mat?ria natural), uma vez que maiores inclus?es acarretam em aumento desfavor?vel da mat?ria seca, nitrog?nio amoniacal e redu??o dos teores de carboidratos sol?veis. A partir dos 30 dias ap?s ensilagem, o material ensilado j? apresentava tend?ncia ? estabiliza??o. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Zootecnia, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2016. / The objective of this study was to evaluate the effects of inclusion levels of crambe meal (Crambe abyssinica Hoechst) the fermentative profile and nutritional value of the silage sugarcane evaluated in different opening times of the silos. The experiment took place at the Experimental Farm of Moura, belonging to the Federal University of the Jequitinhonha and Mucuri Valleys (UFVJM), located in the municipality of Curvelo, MG and the laboratory analyzes performed at the Animal Nutrition Laboratory, Department of Animal Science UFVJM Campus Diamantina, MG. A completely randomized 4 x 4 factorial design was adopted, with four levels of addition of crambe meal (CM: 0, 5, 10 and 20%, based on natural materials) and four days of opening of silos (10; 20; 30; 60 days after the opening of silos), with four replicates. For the evaluation of the chemical composition was used: dry matter (DM), organic matter (OM), mineral matter (MM), crude protein (CP), ether extract (EE), neutral detergent fiber corrected for ash and protein (NDFap), acid detergent fiber (ADF), total carbohydrates (TC), non-fibrous carbohydrates (NCF) and total digestible nutrients calculated (TDN calculated. Regarding the fermentative profile were evaluated: water activity (AW), hydrogenionic potential (pH), electrical conductivity (EC), soluble carbohydrates (sCHT), ammonia-nitrogen concentration (N-NH3). Data were subjected to regression analysis (P> 0.05). For variable EE, only dose and time effect was observed (P> 0.05). For the factors? interaction (levels of inclusion of CM x opening time) was observed effect for MS, MM, CP, MO, NDFap, ADF, TC, NFC, TDN, CE, AW, sCHT, pH and N-NH3. The addition of crambe meal in sugarcane silage boosted the chemical composition, since there was an increase in DM, CP, NFC, and a reduction in fibrous components (NDFap and ADF), thus providing better quality food. The changes promoted by the addition of the FC to the 20% inclusion in cane silage did not affect the fermentation characteristics of silage. The inclusion of the FC is given to the level of 10% (based on natural matter), since larger inclusions lead in an unfavorable increase in dry matte, ammonia nitrogen and reduced levels of carbohydrates. From 30 days after ensiling, the ensiled material already presented tendency towards stabilization.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal. / Les cellules endothéliales sinusoïdales (CES) sont très sensibles aux dommages induits par la préservation hypothermique. Elles peuvent alors exprimer, suite à une augmentation de leur Ca2+, des molécules d'adhésion perturbant la microcirculation et engendrant des dysfonctions primaires des greffons. Le présent travail a pour but l'étude des effets des changements de composition/température des solutions de reperfusion sur le Ca2+ dans les CES isolées de rat. Les cellules ont été préservées à froid dans la solution de l'Université du Wisconsin (UW) puis réchauffées et reperfusées dans le tampon physiologique HEPES ou dans le UW à 20 ou 37°C. Les changements de température et de solution ou seulement de solution ont induit, chez les CES préservées ou non, une importante augmentation transitoire du Ca2+. Le changement de la température seulement dans le UW ou l'HEPES n'a pas eu d'effet significatif sur le Ca2+. D'autre part, la préservation froide atténuait beaucoup la fréquence et l'intensité de la réponse des CES à l'agoniste ATP. Par ailleurs, une coloration des CES au Hoechst et à l'iodure de propidium démontrait des taux d'apoptose et de nécrose augmentant proportionnellement au temps de préservation. Les taux d'apoptose étaient plus importants que ceux de nécrose. Ainsi, les changements de composition des solutions de reperfusion ont un plus grand effet sur le Ca2+ des CES que les changements de température. Les temps de préservation hypothermique n'ont pas d'impacts importants sur le Ca2+, mais affectent une réponse à l'agoniste ATP, et induisent des taux d'apoptose et de nécrose augmentant graduellement.

Infections arising from multidrug-resistant pathogenic bacteria are spreading rapidly throughout the world and threaten to become untreatable. The origins of resistance are numerous and complex, but one underlying factor is the capacity of bacteria to rapidly export drugs through the intrinsic activity of efflux pumps. In this work, a summary is provided of our current understanding of the structures and molecular mechanisms of multidrug efflux pumps in bacteria (Chapter 1). The emerging picture of the structure, function and regulation of efflux pumps suggests opportunities for countering their activities. Although this thesis primarily explores structure and function, it also elucidates the hidden regulatory mechanism (post-translational) behind the association of a small protein called AcrZ with the tripartite complex AcrAB/TolC, in connection with the lipid environment, and the resulting changes in the latter's functionality (Chapter 2). A regulatory role of the native membrane lipid environment as well as of small proteins for efflux pump activity have previously been hypothesised. I present the first example of a function-regulating role of the lipid cardiolipin in combination with a small protein binding partner (AcrZ) for the substrate selectivity and transport activity of an efflux pump protein (AcrB). This regulation happens through induced structural changes which have remained unseen so far. Alongside with these results, a nanodisc reconstitution method was experimentally adapted for a structure-function investigation of an efflux pump (complex) using cryo-EM (Chapter 2). Beyond some fundamental regulatory insights, hidden intrinsic transport mechanisms for some transporters have also remained to be explored and studied. The discovery of a mechanism for active influx by a prominent efflux pump model system (Chapter 3) provides hope that this phenomenon is more common amongst multidrug transporters and that it could be utilised for drug discovery purposes. This novel feature explains the contradictory findings on this transporter in the past and raises new questions about the little-known physiological role and evolution of efflux pumps. The development and evolution of antimicrobial resistance has frequently shown to be a multifactorial and fast-moving process. One of these factors is the evolution of pumps itself towards an altered functionality (e.g. towards a broader or altered substrate spectrum or higher efflux rates). Against this background, the role of key carboxylate residues for efflux-energising proton trafficking was investigated for a prominent study model of a secondary-active transporter (Chapter 4). The re-allocation and/or addition of acidic residues was demonstrated to result in the preservation of wild type activity or the generation of hyper-efflux activity, respectively. These findings suggest that rapid emergence of antimicrobial resistance could be enhanced by the 'plasticity' in the location of key carboxylate residues with a role in proton coupling. It also demonstrates the necessity of antimicrobial drug design programmes to anticipate possible trajectories of an adaptive evolution of efflux pump. The 'cryo-EM revolution' has boosted the pace at which new structural and functional insights into multidrug efflux pumps are gained. Nevertheless, in order to derive the structure of individual pump components or of a full assembly, it is sometimes necessary to identify and characterise homologues and mutants, which would allow the application of cryo-EM for obtaining near-atomic maps. Functional analyses presented in this work helped to characterise a homologue and mutants of the MacAB/TolC tripartite complex to justify the obtained protein structures and strategies for further functional characterisation (Chapter 5). Given (1) the unusual stoichiometry of a MacB dimer in complex with a hexameric membrane-fusion protein (MacA), which leads to a seeming leakiness of the assembly, and (2) the fact that substrate has to pass through a narrow aperture in the membrane-fusion protein for extrusion, it is rather surprising that MacB was previously shown to transport an entire toxin. An experimental approach was developed that could enable the structure determination of a toxin-bound full assembly of MacAB/TolC (Chapter 5). Finally, the role of multidrug efflux pumps for the evolution of multidrug resistance is yet to be studied and better explored. For instance, evolutionary trajectories of pump overexpression, as compared to those of regular expression or no expression, are unknown yet could have the potential to reveal useful insights for spread prevention and drug design. The outline of an experimental design with some preliminary validating data is presented in Chapter 6.

La transferencia nuclear de células somáticas (SCNT) en la especie porcina se ha convertido en una herramienta muy útil para para la elaboración de modelos genéticos de enfermedades humanas y para el uso en xenotransplantes. Aunque el número de cerdos clonados aumenta cada año, la eficiencia total de esta tecnología es todavía muy baja. Uno de los pasos más difíciles de la SCNT en porcino es la enucleación del ovocito, principalmente debido a que su citoplasma contiene numerosas gotas lipídicas. El principal objetivo de la tesis fue evaluar el efecto de diversas técnicas para visualizar la placa metafásica y el corpúsculo polar sobre la capacidad de desarrollo de ovocitos porcinos madurados in vitro. / Somatic cell nuclear transfer (SCNT) technology in porcine has become a very useful tool for the elaboration of genetic models for human diseases and the use in xenotransplantation. The efficiency of SCNT is still very low, although the number of cloned pigs increases each year. One of the hardest steps of porcine SCNT is the enucleation of the oocyte because its cytoplasm contains many lipid droplets. The main objective of this thesis was to assess the effect of several approaches to visualize the metaphase II plate and the first polar body on the developmental ability of in vitro mature porcine oocytes.

Traditionnellement associée à la reproduction féminine, l'ocytocine (OT), une hormone peptidique synthétisée par les noyaux paraventriculaire et supraoptique de l'hypothalamus et sécrétée par l'hypophyse postérieure (neurohypophyse), a été récemment revue et a été démontrée avoir plusieurs nouveaux rôles dans le système cardio-vasculaire. En effet, notre laboratoire a montré que l’OT peut induire la différenciation des cellules souches embryonnaires (CSE) en cardiomyocytes (CM) fonctionnels. À l’aide du modèle cellulaire embryonnaire carcinomateux de souris P19, il a été démontré que ce processus survenait suite à la libération de la guanosine monophosphate cyclique (GMPc) dépendante du monoxyde d’azote. De même, il est connu que le peptide natriurétique auriculaire (ANP), un peptide produit, stocké et sécrété par les myocytes cardiaques, peut aussi induire la production du GMPc. De nombreuses études ont démontré que le cœur ayant subi un infarctus pouvait être régénéré à partir d’une population isolée de cellules souches et progénitrices transplantées. Une de ces populations de cellules, fréquemment isolées à partir d'organes provenant d'animaux aux stades de développement embryonnaire et adulte, appelée « Side Population » (SP), sont identifiées par cytométrie en flux (FACS) comme une population de cellules non marquées par le colorant fluorescent Hoechst 33342 (Ho). Les cellules SP expriment des protéines de transport spécifiques, de la famille ATP-binding cassette, qui ont pour rôle de transporter activement le colorant fluorescent Ho de leur cytoplasme. La sous-population de cellules SP isolée du cœur affiche un potentiel de différenciation cardiaque amélioré en réponse à un traitement avec l’OT. Récemment, l'hétérogénéité phénotypique et fonctionnelle des CSE a été mise en évidence, et cela a été corrélé avec la présence de sous-populations cellulaires ressemblant beaucoup aux cellules SP issues du cœur. Puisque l’ANP peut induire la production du GMPc et qu’il a été démontré que la différenciation cardiaque était médiée par la production du GMPc, alors nous émettons l'hypothèse selon laquelle l’ANP pourrait induire la différenciation cardiaque. Étant donné que les CSE sont composés d’un mélange de différents types cellulaires alors nous émettons aussi l’hypothèse selon laquelle l’utilisation d’une sous-population de CSE plus homogène renforcerait le potentiel de différenciation de l'ANP. Méthodes : Les SP ont été isolées des cellules P19 par FACS en utilisant la méthode d’exclusion du colorant fluorescent Ho. Puis, leur phénotype a été caractérisé par immunofluorescence (IF) pour les marqueurs de l’état indifférencié, d’auto-renouvellement et de pluripotence octamer-binding transcription factor 4 (OCT4) et stage-specific embryonic antigen-1 (SSEA1). Ensuite, la dose pharmacologique optimale d’ANP a été déterminée via des tests de cytotoxicité sur des cellules P19 (MTT assay). Pour induire la différenciation en cardiomyocytes, des cellules à l’état de sphéroïdes ont été formées à l’aide de la technique du « Hanging-Drop » sous la stimulation de l’ANP pendant 5 jours. Puis, des cryosections ont été faites dans les sphéroïdes afin de mettre en évidence la présence de marqueurs de cellules cardiaques progénitrices tels que GATA4, Nkx2.5 et un marqueur mitochondrial spécifique Tom22. Ensuite, les cellules SP P19 ont été stimulées dans les sphéroïdes cellulaires par le traitement avec de l'ANP (10-7 M) ou de l’OT (10-7 M), de l’antagoniste spécifique du guanylate cyclase particulé (GCp) A71915 (10-6 M), ainsi que la combinaison des inducteurs OT+ANP, OT+A71915, ANP+A71915. Après la mise en culture, la différenciation en cardiomyocytes a été identifié par l’apparition de colonies de cellules battantes caractéristiques des cellules cardiaques, par la détermination du phénotype cellulaire par IF, et enfin par l’extraction d'ARN et de protéines qui ont été utilisés pour le dosage du GMPc par RIA, l’expression des ARNm par RT-PCR et l’expression des protéines par immunobuvardage de type western. Résultats : Les sphéroïdes obtenus à l’aide de la technique du « Hanging-Drop » ont montré une hausse modeste de l’expression des ARNm suivants : OTR, ANP et GATA4 comparativement aux cellules cultivées en monocouches. Les sphéroïdes induits par l’ANP ont présenté une augmentation significative des facteurs de transcription cardiaque GATA4 et Nkx2.5 ainsi qu’un plus grand nombre de mitochondries caractérisé par une plus grande présence de Tom22. De plus, L’ANP a induit l’apparition de colonies de cellules battantes du jour 7 (stade précoce) au jour 14 (stade mature) de façon presque similaire à l’OT. Cependant, la combinaison de l’ANP avec l’OT n’a pas induit de colonies de cellules battantes suggérant un effet opposé à celui de l’OT. Par IF, nous avons quantifié (nombre de cellules positives) et caractérisé, du jour 6 au jour 14 de différenciation, le phénotype cardiaque de nos cellules en utilisant les marqueurs suivants : Troponine T Cardiaque, ANP, Connexines 40 et 43, l’isoforme ventriculaire de la chaîne légère de myosine (MLC-2v), OTR. Les SP différenciées sous la stimulation de l’ANP ont montré une augmentation significative du GMPc intracellulaire comparé aux cellules non différenciées. À notre grande surprise, l’antagoniste A71915 a induit une plus grande apparition de colonies de cellules battantes comparativement à l’OT et l’ANP à un jour précoce de différenciation cardiaque et l’ajout de l’OT ou de l’ANP a potentialisé ses effets, augmentant encore plus la proportion de colonies de cellules battantes. De plus, la taille des colonies de cellules battantes était encore plus importante que sous la simple stimulation de l’OT ou de l’ANP. Les analyses radioimmunologiques dans les cellules SP P19 stimulés avec l’ANP, A71915 et la combinaison des deux pendant 15min, 30min et 60min a montré que l’ANP stimule significativement la production du GMPc, cependant A71915 n’abolit pas les effets de l’ANP et celui-ci au contraire stimule la production du GMPc via des effets agonistes partiels. Conclusion : Nos résultats démontrent d’une part que l’ANP induit la différenciation des cellules SP P19 en CM fonctionnels. D’autre part, il semblerait que la voie de signalisation NPRA-B/GCp/GMPc soit impliquée dans le mécanisme de différenciation cardiaque puisque l’abolition du GMPc médiée par le GCp potentialise la différenciation cardiaque et il semblerait que cette voie de signalisation soit additive de la voie de signalisation induite par l’OT, NO/GCs/GMPc, puisque l’ajout de l’OT à l’antagoniste A71915 stimule plus fortement la différenciation cardiaque que l’OT ou l’A71915 seuls. Cela suggère que l’effet thérapeutique des peptides natriurétiques observé dans la défaillance cardiaque ainsi que les propriétés vasodilatatrices de certains antagonistes des récepteurs peptidiques natriurétiques inclus la stimulation de la différenciation des cellules souches en cardiomyocytes. Cela laisse donc à penser que les peptides natriurétiques ou les antagonistes des récepteurs peptidiques natriurétiques pourraient être une alternative très intéressante dans la thérapie cellulaire visant à induire la régénération cardiovasculaire. / Traditionally associated with female reproduction, oxytocin (OT), a peptidic hormone synthesized in the paraventricular and supraoptic nuclei of the hypothalamus and secreted by the posterior pituitary (neurohypophysis), was revisited recently and was revealed to have several new roles in the cardiovascular system. Indeed, our laboratory has shown that OT can induce the differentiation of embryonic stem cells (ESC) into functional cardiomyocytes (CM). On the model of embryonal carcinoma cell line P19, it has been shown that this process occurs following the release of cyclic guanosine monophosphate (cGMP)-dependent nitric oxide. Similarly, it is known that atrial natriuretic peptide (ANP), a peptide produced, stored and secreted by cardiac myocytes, can also induce the release of cGMP. However, the cellular mechanisms involved in cardiac differentiation are still poorly understood. Numerous studies have shown that the injured heart can be regenerated from an isolated population of transplanted stem and progenitor cells. One of these cell populations, frequently isolated from embryonic and adult animal organs, called "Side Population" (SP), is characterized by active efflux of the fluorescent dye Hoechst 33342 (Ho). SP cells express specific ATP-binding cassette transporter proteins which actively transport Ho out of their cytoplasm. The SP cell subpopulation isolated from the heart display enhanced differentiation potential into cardiac phenotype in response to OT treatment. Recently, the phenotypic and functional heterogeneity of embryonic stem cells has been demonstrated, and this was correlated with the presence of cell subpopulations much like the SP cells from the heart and these cells can be identified by flow cytometry (FACS) as a population of unmarked cells by the Ho and which exhibit sensitivity to the inhibitor of the family of ATP-binding cassette ABC, verapamil. Thus, the SP from ESC could be a good candidate to induce cell differentiation more effectively to the cardiac phenotype. Since ANP can induce the release of cGMP and it has been shown that cardiac differentiation was mediated by the release of cGMP through the nitric oxide (NO), then we therefore formulate the hypothesis that ANP could also induce cardiac differentiation. Since ESC are composed of a mixture of different cell types so as we emit the hypothesis that the use of a subpopulation of more homogeneous ESC strengthen the differentiation potential of ANP. Methods: SP were isolated from P19 cells by FACS using the method of exclusion of fluorescent dye Hoechst and their phenotype was characterized by immunofluorescence (IF) for markers of the undifferentiated state, self-renewal and pluripotency OCT4 and SSEA1. Then, the optimal pharmacological dose of ANP was determined via cytotoxicity tests in P19 cells (MTT assay). For cardiac differentiation, cells in the form of spheroids were formed using the technique of "Hanging Drop" under the stimulation of ANP for 5 days. Then cuts were made in the spheroids via cryosection to highlight the presence of cardiac progenitor cell markers such as GATA4, Nkx2.5 and a specific mitochondrial marker Tom22. Next, the P19-SP cells were stimulated in cell spheroids by the treatment with ANP (10-7 M) or OT (10-7 M), the specific antagonist of particulate guanylate cyclase A71915 (10-6 M), and the combination of the inducers OT + ANP, OT + A71915, A71915 + ANP. After cell plating, the differentiation into cardiomyocytes has been identified by the appearance of beating cell colonies characteristics of contractile cardiac cells, by determining the cellular phenotype by IF, and finally by the extraction of RNA and proteins that were used for the determination of cGMP by RIA, the mRNA expression by RT-PCR and protein expression by western blotting. Results: The spheroids induced by ANP showed a significant increase in the presence of cardiac transcription factors GATA4 and Nkx2.5 as well as a greater number of mitochondria characterized by a greater presence of Tom22 compared with no induced cells suggesting a cardiomyogenic effect of ANP. In addition, ANP induced the appearance of beating cell colonies from day 7 (early stage) to day 14 (mature stage) similarly to OT. However, the combination of ANP with OT did not induce beating cell colonies suggesting a negative additive effect on cardiomyogenesis. The spheroids, obtained using the technique of "Hanging Drop", have shown a modest increase in mRNA expression as follows: OTR, ANP and GATA4 compared to cells grown in monolayers. By IF, we quantified (number of positive cells) and characterized, from day 6 to day 14 of differentiation, the cardiac phenotype of our cells using the following markers: Cardiac Troponin T, ANP, Connexines 40 and 43, Myosin Light Chain-2V, OTR. The SP differentiated under the stimulation of ANP showed a significant increase in intracellular cGMP compared with undifferentiated cells. Surprisingly, the antagonist A71915 induced a greater appearance of beating cell colonies compared to OT and ANP in early day of cardiac differentiation and the addition of OT or ANP potentiated its effects, further increasing the proportion of beating cells colonies. In addition, the size of beating cell colonies was even greater than under the simple stimulation of OT or ANP. Radioimmunoassay analysis in SP P19 cells stimulated with ANP, A71915 and the combination of both during 15min, 30min and 60min showed that ANP significantly stimulates the release of cGMP, however, A71915 does not abolish the effects of ANP and it rather stimulates the release of cGMP through partial agonist effects. Conclusion: Our results demonstrate firstly that ANP induces the differentiation of P19-SP cells into functional CM. Moreover, it appears that the signaling pathway NPRA-B/pGC/cGMP seems to be involved in the mechanism of cardiac differentiation since the abolition of cGMP mediated by the pGC potentiates cardiac differentiation and it appears that this signaling pathway is additive to the signaling pathway induced by OT, NO/sGC/cGMP, since the addition of OT to the antagonist A71915 stimulates cardiac differentiation more strongly than OT or A71915 alone. This suggests that the therapeutic effect of natriuretic peptides observed in heart failure and vasodilatory properties of certain natriuretic peptide receptor antagonists included the stimulation of stem cell differentiation into cardiomyocytes. This would therefore suggest that the natriuretic peptides or natriuretic peptide receptor antagonists could be an attractive alternative to cell therapy to induce heart regeneration.

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This article analyzes the scope of the non-discrimination rule contained in Double Taxation Avoidance Treaties, especially those signed by Argentina. This document considers the OECD and the ILADT Models, which contain provisions designed to ensure that Contracting States do not give any preferential treatment in taxing its own residents or citizens as opposed to the treatment granted to non-residents. Additionally, it analyzes the recent jurisprudence in the Argentine Courts. / En el artículo se analiza el concepto y alcance del principio de “no discriminación” contenido en los Convenios para evitar la Doble Imposición, con especial énfasis en aquellos suscriptos por la República Argentina. Se analizan los Modelos de Convenio OCDE e ILADT, los cuales contienen provisiones diseñadas para prevenir que un Estado contratante otorgue a sus residentes o nacionales un tratamiento impositivo preferencial en relación al otorgado a los no residentes. Adicionalmente, se analiza la reciente jurisprudencia de los tribunales argentinos aplicable en la materia.