Pluripotent cells are unique due to their developmental potential and the possibility to study them is the key step to understand human development. These cells are characterized by their ability to originate all the cellular lineages within an adult organism. Within embryonic milieu, pluripotent cells represent a dynamic fraction of the total cell number. Moreover, their physiological existence is constrained to early stages of embryonic development. In vitro culture of the different types of mammalian pluripotent cells, and singularly embryonic stem cells (ESC), enables the characterization of the pluripotent state. In the four articles included in this thesis we have addressed two different aspects of the molecular characterization of mammalian pluripotent cells. First, we investigated the establishment of the trophectoderm and the inner cell mass in the embryo measuring transcript abundance and protein presence of the transcription factors known to play a role in the earliest cellular differentiation process. In addition we have evaluated of genomic stability of human ESC lines during long-term culture, observing the accumulation of sukaryotypic aberrations such as loss of heterozygosity that affect loci comprising genes involved in genomic stability maintenance. We also checked the genomic status of two human ESC lines derived from embryos that had been diagnosed as abnormal after genetic preimplantation diagnosis (PGD). The molecular analysis of these cells ruled out the hypothesized self-correction of the aneuploidies between the PGD and the establishment of the cell lines. / Les cèl·lules pluripotents són úniques atesa la seva plasticitat durant el desenvolupament i la possibilitat d'estudiar-les és un pas essencial per poder comprendre el desenvolupament embrionari. Aquestes cèl·lules es caracteritzen per la seva habilitat per donar lloc a tots els llinatges cel·lulars de l'organisme. Dins de l'embrió, les cèl·lules pluripotents representen una fracció dinàmica del nombre total de cèl·lules i la seva existència fisiològica està constreta a els estadis més primerencs del desenvolupament embrionari. El cultiu in vitro dels diferents tipus de cèl·lules pluripotents en mamífers, i en especial les cèl·lules mare embrionàries, permet la caracterització d'aquest estat cel·lular. En els quatre capítols inclosos en aquesta tesi, hem tractat dos aspectes diferents de la caracterització molecular de les cèl·lules pluripotents. Primer, hem investigat l'establiment del trofectoderm i de la massa cel·lular interna en l'embrió mesurant l'abundància dels trànscrits i la presència de proteina dels factors de transcripció implicats en el primer process de diferenciació cel·lular conegut. A més, hem avaluat l'estabilitat genòmica de dues línies de cèl·lules mare en cultiu durant més de 40 passis. Com a resultat, hem observat l'acumulació de aberracions genòmiques a nivell subcariotípic, en especial pèrdua d'heterozigositat que afecta a locus que contenen gens implicats en el manteniment de l'estabilitat genòmica. També hem comprovat l'estatus genòmic de dos linies de cèl·lules mare embrionàries humanes derivades a partir d'embrions trobats aneuploids per un diagnòstic genètic preimplantacional. L'anàlisi molecular d'aquestes cèl·lules va descartar la hipòtesi d'una autocorrecció de les aneuploidies detectades entre el diagnòstic preimplantacional i la derivació de les línies a partir d'aquests embrions.

O desenvolvimento de uma abordagem de estratificação de risco para a doença arterial coronária é certamente uma ferramenta de grande utilidade para o cardiologista clínico ou clínico geral, assim como para o planejamento de saúde pública e organização de ações de saúde pública mais eficazes. No entanto, esse conhecimento deve ser discutido dentro de um cenário de custo-efetividade e de acordo com seu potencial como objeto de valor econômico. O presente estudo tem como objetivo a identificação de fatores de risco genético de eventos cardiovasculares na população brasileira e o desenvolvimento de um algoritmo preditor que utilize essas informações para o diagnóstico. Esse trabalho encontra-se expositivamente dividido em dois módulos. No primeiro, procuramos exemplificar através de um estudo de associação genética nossa capacidade atual de encontrar e caracterizar variantes genéticas com poder de estratificação populacional com relação ao risco cardiovascular. Utilizamos dados obtidos a partir de pacientes com doença coronária multiarterial, analisando a relevância do polimorfismo C242T do gene da p22phox, subunidade protéica da NADPH oxidase, na predição de mortalidade desta população. Nossos dados permitem não apenas associar esse marcador genético a um risco aumentado de mortalidade nessa população, mas também fornecem informações a respeito do provável mecanismo molecular através do qual esse marcador genético age. No segundo módulo, procuramos detalhar as limitações da abordagem previamente exemplificada, avaliando a informação gerada para o paciente individual. Aqui propomos uma nova abordagem de estratificação de risco desta população, capaz de fornecer de maneira individualizada uma estimativa de risco com maior sensibilidade, especificidade e, conseqüentemente, acurácia. Através de uma abordagem analítica de redução de dimensionalidade obtivemos um algoritmo preditor com acurácia maior do que aquela encontrada utilizando-se apenas os fatores de risco clássicos ou fatores de risco genéticos analisados individualmente. O entendimento das bases genéticas do desenvolvimento de doenças cardiovasculares facilitará não apenas o diagnóstico precoce, possibilitando o surgimento de abordagens terapêuticas mais específicas e desenhadas a atender suscetibilidades individuais, mas também poderá levar à identificação de novas vias eficazes de intervenção. / The development of risk stratification approaches in coronary artery disease is certainly an important tool for the clinical cardiologist or internist. It also helps in the planning of public health policies and in the development of effective disease management algorithms. Nevertheless, these tools necessarily have to be developed in a cost-effective scenario and in close relationship with its intrinsic economic value. The present research project aims at the identification of genetic risk factors for cardiovascular events in the Brazilian population and the development of an algorithm with high predictive value for the diagnosis of these events. This thesis is, didactically, divided into 2 modules. Firstly, we have exemplified the used paradigm through the development of a genetic association study conducted in the Brazilian population. Here, we were able to describe and characterize genetic variants with the capacity of risk stratify populations into high and low risk groups. This section was possible with the use of data derived from patients with multi-vessel coronary artery disease and the analysis of the C242T gene variant of the p22phox gene, a subunit of the NADPH oxidase protein complex. Our data show not only a major signal of association between this genetic variant and overall mortality in this population, but also shed light on the potential molecular mechanism of this finding. Secondly, we have described the potential limitations of this approach analyzing information derived for the individual patient. Here, we propose a new risk stratification algorithm for this population with the capacity to provide individual risk with increased sensitivity and specificity. Through the use of a dimensionality reduction analytical approach we were able to find a predictive algorithm with higher accuracy than the one derived with the use of only classical cardiovascular risk factors and no genetic information. The understanding of the genetic basis for cardiovascular disease will improve not only the early diagnosis of these disorders, facilitating the rise of therapeutic approaches more specific and tailored to ones particular genetic susceptibility, but also lead to the identification of new pathways for effective intervention

[Truncated abstract] Background: A review of the literature indicated there was a need for more long-term randomised controlled studies on the effects of BRCA counselling/testing on high risk women, including improved strategies for risk communication. Reviews have also shown women are confused about the significance of inconclusive or non informative results with a need for more research in this area. Aims: The general aim of this study was to evaluate the impact of breast cancer genetic counselling on psychological distress levels, perception of risk, genetic knowledge and understanding of BRCA testing/test results in a cohort of 207 women from high risk breast cancer families who were referred for genetic counselling in Perth during the period 1997 to 2001. Short- and long-term impact of BRCA genetic counselling/testing was determined in women with and without cancer in a randomised controlled trial as part of which women were randomised to either receive immediate versus delayed genetic counselling. This included family communication patterns before BRCA testing, anticipated outcomes of testing on oneself and family including intentions for result disclosure. Comprehension of index and predictive BRCA testing with possible results was assessed both in the short- and the long-term and understanding of individual or family BRCA test results was evaluated at long-term. The effect of genetic counselling on breast cancer risk perception in unaffected women was evaluated. This study considered a theoretical framework of educational learning theories to provide a basis for risk communication with possible relevance for future research. ... Only 25% of the original study population (52/207) reported BRCA results and women's understanding of results is concerning. Key findings were: 1. The majority of affected women received an inconclusive result. 2. Out of twelve unaffected women who reported results, seven were inconclusive which are not congruent with predictive testing. This implies that these women did not understand their test result. 3. A minority of untested relatives did not know whether a family mutation had or had not been found in their tested family member or what their actual test result was. This implies either a lack of disclosure or that woman did not understand the rationale for and significance of testing for a family mutation. 4. Three relatives did not understand a positive result was a mutation. Conclusion: The implication of this research for breast cancer counselling and testing services is that women who wait for counselling are no worse off in terms of short- or long-term general psychological distress than women who receive the intervention early. There is a suggestion that unaffected women without the disease found counselling more advantageous than affected women. The meaning of BRCA results as reported by women is concerning particularly women's understanding of negative and inconclusive results and further research is needed in this area. Too much information presented at counselling may affect women's comprehension of risk, BRCA testing and future test results and further research is required to evaluate the effects of information overload.

This study is on the political and ethical aspects of recent advances in genetics. Its aim is to explicate the scientific and technological premises of genetics along historical, philosophical and political axes by employing the critical perspectives of Jonas, Heidegger and Foucault. Starting the discussion from a brief account of scientific and technological revolutions initiated in the 16th and 17th centuries, I defend the thesis that the idea of control and manipulation of life is not a novelty introduced by genetics, but a historical orientation underlying modern man&rsquo / s metaphysical reasoning. That is to say, &lsquo / the idea of control and manipulation of life&rsquo / is not an unintended technological excess of genetic practices, and hence a transgression of our moral principles. Rather, this endeavour is a scientific and technological &lsquo / project&rsquo / which has been at the very core of modern man&rsquo / s rational political agenda. Therefore, any attempts to understand genetics from a na&iuml / ve Baconian utilitarianism and optimism fails to grasp its complicated political nature. For the ethical concerns to become more comprehensive, three genetic cases (prenatal screening tests, cloning, and genetic engineering) are examined in the light of the philosophical reflections of Jonas and Heidegger. Besides, following Foucault&rsquo / s critical assessments of medicine and bio-power, a &lsquo / fourth spatialization of disease&rsquo / is proposed at the end of the study in order to evaluate the transformations with the introduction of genetics into medicine. Consequently, it is argued that geneticized medicine might sign a new regime of bio-power &ndash / a reconfiguration of knowledge, power and subjectivity.

En el llevat Saccharomyces cerevisiae els canvis en les condicions osmòtiques del medi extracel.lular són sensades per la MAP cinasa Hog1, la qual permet dur a terme l'adaptació cel.lular mitjançant la modulació de l'expressió gènica, de la traducció i de la progressió del cicle cel.lular. A l'inici d'aquest projecte de tesi, els mecanismes pels quals Hog1 controla l'expressió gènica no eren del tot coneguts. El nostre objectiu va ser caracteritzar el mecanisme molecular pel qual Hog1 modula la transcripció en resposta a estrès osmòtic. Hem aconseguit demostrar que el reclutament de Hog1 als promotors sensibles a estrès osmòtic per part del factor de transcripció és essencial per al reclutament i activació de la RNA polimerasa II, mecanisme que podria estar conservat en les cèl.lules eucariotes. També hem identificat noves activitats remodeladores de cromatina implicades en la resposta gènica a osmoestrès mediada per Hog1. Vàrem realitzar un cribatge genètic per identificar mutacions que provoquessin osmosensibilitat i una reducció en l'expressió de gens de resposta a estrès osmòtic. Aquest cribatge ens va permetre identificar nous reguladors de la transcripció mediada per osmoestrès: la histona deacetilasa Rpd3 i els complexes SAGA i mediador. Els nostres resultats permeten, doncs, definir un important paper per a Rpd3, SAGA i mediador en la inducció gènica mediada per Hog1, i han estat importants per assolir una millor visió de com les cinases activades per estrès regulen la iniciació de la transcripció. / In Saccharomyces cerevisiae, changes in the extracellular osmotic conditions are sensed by the HOG MAPK pathway, which elicits the program for cell adaptation, including modulation of gene expression, translation and cell-cycle progression. At the beginning of this PhD Project, the mechanisms by which Hog1 was controlling gene transcription were not completely understood. Our main objective was to characterize the molecular mechanisms by which the Hog1 MAPK modulates transcription upon osmostress. We have shown that anchoring of Hog1 to osmoresponsive promoters by the transcription factor is essential for recruitment and activation of RNA polymerase II, a mechanism that might be conserved among eukaryotic cells. In addition, we identified novel chromatin modifying and remodelling activities involved in the Hog1-mediated osmostress gene expression. We performed a genome-wide genetic screening searching for mutations that render cells osmosensitive and displayed reduced expression of osmoresponsive genes. Rpd3 histone deacetylase, SAGA and Mediator complexes were identified as novel regulators of osmostress-mediated transcription. Thus, our results define a major role for Rpd3, SAGA and Mediator in the Hog1-mediated osmostress gene induction, and have been important to achieve a better view of how a SAPK regulates transcription initiation.