90 resultados para critical period for weed control
Resumo:
BACKGROUND: There are no time trends in prevalence, unawareness, treatment, and control of hypertension in Switzerland. The objective of this study was to analyze these trends and to determine the associated factors. METHODS/FINDINGS: Population-based study conducted in the Canton of Geneva, Switzerland, between 1999 and 2009. Blood pressure was measured thrice using a standard protocol. Hypertension was defined as mean systolic or diastolic blood pressure ≥140/90 mmHg or self-reported hypertension or anti-hypertensive medication. Unawareness, untreated and uncontrolled hypertension was determined by questionnaires/blood pressure measurements. Yearly age-standardized prevalences and adjusted associations for the 1999-2003 and 2004-2009 survey periods were reported. The 10-year survey included 9,215 participants aged 35 to 74 years. Hypertension remained stable (34.4%). Hypertension unawareness decreased from 35.9% to 17.7% (P<0.001). The decrease in hypertension unawareness was not paralleled by a concomitant absolute increase in hypertension treatment, which remained low (38.2%). A larger proportion of all hypertensive participants were aware but not treated in 2004-2009 (43.7%) compared to 1999-2003 (33.1%). Uncontrolled hypertension improved from 62.2% to 40.6% between 1999 and 2009 (P = 0.02). In 1999-2003 period, factors associated with hypertension unawareness were current smoking (OR = 1.27, 95%CI, 1.02-1.59), male gender (OR = 1.56, 1.27-1.92), hypercholesterolemia (OR = 1.31, 1.20-1.44), and older age (OR 65-74yrs vs 35-49yrs = 1.56, 1.21-2.02). In 1999-2003 and 2004-2009, obesity and diabetes were negatively associated with hypertension unawareness, high education was associated with untreated hypertension (OR = 1.45, 1.12-1.88 and 1.42, 1.02-1.99, respectively), and male gender with uncontrolled hypertension (OR = 1.49, 1.03-2.17 and 1.65, 1.08-2.50, respectively). Sedentarity was associated with higher risk of hypertension and uncontrolled hypertension in 1999-2003. CONCLUSIONS: Hypertension prevalence remained stable since 1999 in the canton of Geneva. Although hypertension unawareness substantially decreased, more than half of hypertensive subjects still remained untreated or uncontrolled in 2004-2009. This study identified determinants that should guide interventions aimed at improving hypertension treatment and control.
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In neurons, the regulation of microtubules plays an important role for neurite outgrowth, axonal elongation, and growth cone steering. SCG10 family proteins are the only known neuronal proteins that have a strong destabilizing effect, are highly enriched in growth cones and are thought to play an important role during axonal elongation. MAP1B, a microtubule-stabilizing protein, is found in growth cones as well, therefore it was important to test their effect on microtubules in the presence of both proteins. We used recombinant proteins in microtubule assembly assays and in transfected COS-7 cells to analyze their combined effects in vitro and in living cells, respectively. Individually, both proteins showed their expected activities in microtubule stabilization and destruction respectively. In MAP1B/SCG10 double-transfected cells, MAP1B could not protect microtubules from SCG10-induced disassembly in most cells, in particular not in cells that contained high levels of SCG10. This suggests that SCG10 is more potent to destabilize microtubules than MAP1B to rescue them. In microtubule assembly assays, MAP1B promoted microtubule formation at a ratio of 1 MAP1B per 70 tubulin dimers while a ratio of 1 SCG10 per two tubulin dimers was needed to destroy microtubules. In addition to its known binding to tubulin dimers, SCG10 binds also to purified microtubules in growth cones of dorsal root ganglion neurons in culture. In conclusion, neuronal microtubules are regulated by antagonistic effects of MAP1B and SCG10 and a fine tuning of the balance of these proteins may be critical for the regulation of microtubule dynamics in growth cones.
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Pseudomonas aeruginosa, une bactérie environnementale ubiquitaire, est un des pathogènes nosocomiaux les plus fréquents aux soins intensifs. La source de ce microorganisme peut être soit endogène, 2,6 à 24 % des patients hospitalisés étant colonisés au niveau digestif, soit exogène. La proportion des cas d'infections à P. aeruginosa d'origine exogène, donc secondaires à une transmission par manuportage ou par l'eau du réseau utilisée pour la toilette ou d'autres soins, reste débattue. Or une meilleure évaluation du taux d'infections exogènes est importante pour la mise en place de mesures de contrôle appropriées. Le but de cette étude était de déterminer sur une période de 10 ans les rôles respectifs des sources exogènes (robinets, autres patients) et endogène dans la colonisation et/ou l'infection par P.aeruginosa chez les patients des Soins Intensifs, ainsi que de documenter les variations épidémiologiques au cours du temps. L'étude a été menée dans les unités de Soins Intensifs du Centre Hospitalier Universitaire Vaudois (CHUV). Les patients colonisés et/ou infectés par P. aeruginosa entre 1998 et 2007ont été identifiés via la base de données du laboratoire de microbiologie. Ils ont été inclus dans l'étude s'ils étaient hospitalisés dans une des unités de Soins Intensifs, Durant cette période, des prélèvements pour recherche de P. aeruginosa ont été effectués sur des robinets des soins intensifs. Un typage moléculaire a été effectué sur toutes les souches cliniques et environnementales isolées en 1998, 2000, 2003, 2004 et 2007. Les patients inclus dans l'étude ont été répartis en quatre catégories (A-D) selon le résultat du typage moléculaire leur souche de P. aeruginosa. La catégorie A inclut les cas pour lesquels le génotype de P. aeruginosa est identique à un des génotypes retrouvé dans l'environnement. La catégorie B comprend les cas pour lesquels le génotype est identique à celui d'au moins un autre patient. La catégorie C comprend les cas avec un génotype unique et la catégorie D comprend les cas pour lesquels la souche était non disponible pour le typage. Les cas des catégories A et B sont considérés comme ayant une origine exogène. Au cours des années de l'étude, le nombre d'admissions aux soins intensifs est resté stable. En moyenne, 86 patients par année ont été identifiés colonisés ou infectés par P. aeruginosa aux Soins Intensifs. Durant la première année d'investigation, un grand nombre de patients colonisés par une souche de P. aeruginosa identique à une de celles retrouvées dans l'environnement a été mis en évidence. Par la suite, possiblement suite à l'augmentation de la température du réseau d'eau chaude, le nombre de cas dans la catégorie A a diminué. Dans la catégorie B, le nombre de cas varie de 1,9 à 20 cas/1000 admissions selon les années. Ce nombre est supérieur à 10 cas/1000 admissions en 1998, 2003 et 2007 et correspond à des situations épidémiques transitoires. Tout au long des 10 ans de l'étude, le nombre de cas dans la catégorie C (source endogène) est demeuré stable et indépendant des variations du nombre de cas dans les catégories A et B. En conclusion, la contribution relative des réservoirs endogène et exogène dans la colonisation et/ou l'infection des patients de soins Intensifs varie au cours du temps. Les facteurs principaux qui contribuent à de telles variations sont probablement le degré de contamination de l'environnement, la compliance des soignants aux mesures de contrôle des infections et la génétique du pathogène lui-même. Etant donné que ce germe est ubiquitaire dans l'environnement aqueux et colonise jusqu'à 15% des patients hospitalisés, la disparition de son réservoir endogène semble difficile. Cependant, cette étude démontre que son contrôle est possible dans l'environnement, notamment dans les robinets en augmentant la température de l'eau. De plus, si une souche multi-résistante est retrouvée de manière répétée dans l'environnement, des efforts doivent être mis en place pour éliminer cette souche. Des efforts doivent être également entrepris afin de limiter la transmission entre les patients, qui est une cause importante et récurrente de contamination exogène. - Pseudomonas aeruginosa is one of the leading nosocomial pathogens in intensive care units (ICUs). The source of this microorganism can be either endogenous or exogenous. The proportion of cases as a result of transmission is still debated, and its elucidation is important for implementing appropriate control measures. To understand the relative importance of exogenous vs. endogenous sources of P. aeru¬ginosa, molecular typing was performed on all available P. aeruginosa isolated from ICU clinical and environmental specimens in 1998, 2000, 2003, 2004 and 2007. Patient samples were classified according to their P. aeruginosa genotypes into three categories: (A) identical to isolate from faucet; (B) identical to at least one other patient sample and not found in faucet; and (C) unique genotype. Cases in cat¬egories A and Β were considered as possibly exogenous, and cases in category C as possibly endogenous. A mean of 34 cases per 1000 admissions per year were found to be colonized or infected by P. aeruginosa. Higher levels of faucet contamination were correlated with a higher number of cases in category A. The number of cases in category Β varied from 1.9 to 20 cases per 1000 admissions. This num¬ber exceeded 10/1000 admissions on three occasions and was correlated with an outbreak on one occasion. The number of cases con¬sidered as endogenous (category C) was stable and independent of the number of cases in categories A and B. The present study shows that repeated molecular typing can help identify variations in the epidemiology of P. aeruginosa in ICU patients and guide infection control measures.
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The Helvetic nappe system in Western Switzerland is a stack of fold nappes and thrust sheets em-placed at low grade metamorphism. Fold nappes and thrust sheets are also some of the most common features in orogens. Fold nappes are kilometer scaled recumbent folds which feature a weakly deformed normal limb and an intensely deformed overturned limb. Thrust sheets on the other hand are characterized by the absence of overturned limb and can be defined as almost rigid blocks of crust that are displaced sub-horizontally over up to several tens of kilometers. The Morcles and Doldenhom nappe are classic examples of fold nappes and constitute the so-called infra-Helvetic complex in Western and Central Switzerland, respectively. This complex is overridden by thrust sheets such as the Diablerets and Wildhörn nappes in Western Switzerland. One of the most famous example of thrust sheets worldwide is the Glariis thrust sheet in Central Switzerland which features over 35 kilometers of thrusting which are accommodated by a ~1 m thick shear zone. Since the works of the early Alpine geologist such as Heim and Lugeon, the knowledge of these nappes has been steadily refined and today the geometry and kinematics of the Helvetic nappe system is generally agreed upon. However, despite the extensive knowledge we have today of the kinematics of fold nappes and thrust sheets, the mechanical process leading to the emplacement of these nappe is still poorly understood. For a long time geologist were facing the so-called 'mechanical paradox' which arises from the fact that a block of rock several kilometers high and tens of kilometers long (i.e. nappe) would break internally rather than start moving on a low angle plane. Several solutions were proposed to solve this apparent paradox. Certainly the most successful is the theory of critical wedges (e.g. Chappie 1978; Dahlen, 1984). In this theory the orogen is considered as a whole and this change of scale allows thrust sheet like structures to form while being consistent with mechanics. However this theoiy is intricately linked to brittle rheology and fold nappes, which are inherently ductile structures, cannot be created in these models. When considering the problem of nappe emplacement from the perspective of ductile rheology the problem of strain localization arises. The aim of this thesis was to develop and apply models based on continuum mechanics and integrating heat transfer to understand the emplacement of nappes. Models were solved either analytically or numerically. In the first two papers of this thesis we derived a simple model which describes channel flow in a homogeneous material with temperature dependent viscosity. We applied this model to the Morcles fold nappe and to several kilometer-scale shear zones worldwide. In the last paper we zoomed out and studied the tectonics of (i) ductile and (ii) visco-elasto-plastic and temperature dependent wedges. In this last paper we focused on the relationship between basement and cover deformation. We demonstrated that during the compression of a ductile passive margin both fold nappes and thrust sheets can develop and that these apparently different structures constitute two end-members of a single structure (i.e. nappe). The transition from fold nappe to thrust sheet is to first order controlled by the deformation of the basement. -- Le système des nappes helvétiques en Suisse occidentale est un empilement de nappes de plis et de nappes de charriage qui se sont mis en place à faible grade métamorphique. Les nappes de plis et les nappes de charriage sont parmi les objets géologiques les plus communs dans les orogènes. Les nappes de plis sont des plis couchés d'échelle kilométrique caractérisés par un flanc normal faiblement défor-mé, au contraire de leur flanc inverse, intensément déformé. Les nappes de charriage, à l'inverse se caractérisent par l'absence d'un flanc inverse bien défini. Elles peuvent être définies comme des blocs de croûte terrestre qui se déplacent de manière presque rigide qui sont déplacés sub-horizontalement jusqu'à plusieurs dizaines de kilomètres. La nappe de Mordes et la nappe du Doldenhorn sont des exemples classiques de nappes de plis et constitue le complexe infra-helvétique en Suisse occidentale et centrale, respectivement. Ce complexe repose sous des nappes de charriages telles les nappes des Diablerets et du Widlhörn en Suisse occidentale. La nappe du Glariis en Suisse centrale se distingue par un déplacement de plus de 35 kilomètres qui s'est effectué à la faveur d'une zone de cisaillement basale épaisse de seulement 1 mètre. Aujourd'hui la géométrie et la cinématique des nappes alpines fait l'objet d'un consensus général. Malgré cela, les processus mécaniques par lesquels ces nappes se sont mises en place restent mal compris. Pendant toute la première moitié du vingtième siècle les géologues les géologues ont été confrontés au «paradoxe mécanique». Celui-ci survient du fait qu'un bloc de roche haut de plusieurs kilomètres et long de plusieurs dizaines de kilomètres (i.e., une nappe) se fracturera de l'intérieur plutôt que de se déplacer sur une surface frictionnelle. Plusieurs solutions ont été proposées pour contourner cet apparent paradoxe. La solution la plus populaire est la théorie des prismes d'accrétion critiques (par exemple Chappie, 1978 ; Dahlen, 1984). Dans le cadre de cette théorie l'orogène est considéré dans son ensemble et ce simple changement d'échelle solutionne le paradoxe mécanique (la fracturation interne de l'orogène correspond aux nappes). Cette théorie est étroitement lié à la rhéologie cassante et par conséquent des nappes de plis ne peuvent pas créer au sein d'un prisme critique. Le but de cette thèse était de développer et d'appliquer des modèles basés sur la théorie de la méca-nique des milieux continus et sur les transferts de chaleur pour comprendre l'emplacement des nappes. Ces modèles ont été solutionnés de manière analytique ou numérique. Dans les deux premiers articles présentés dans ce mémoire nous avons dérivé un modèle d'écoulement dans un chenal d'un matériel homogène dont la viscosité dépend de la température. Nous avons appliqué ce modèle à la nappe de Mordes et à plusieurs zone de cisaillement d'échelle kilométrique provenant de différents orogènes a travers le monde. Dans le dernier article nous avons considéré le problème à l'échelle de l'orogène et avons étudié la tectonique de prismes (i) ductiles, et (ii) visco-élasto-plastiques en considérant les transferts de chaleur. Nous avons démontré que durant la compression d'une marge passive ductile, a la fois des nappes de plis et des nappes de charriages peuvent se développer. Nous avons aussi démontré que nappes de plis et de charriages sont deux cas extrêmes d'une même structure (i.e. nappe) La transition entre le développement d'une nappe de pli ou d'une nappe de charriage est contrôlé au premier ordre par la déformation du socle. -- Le système des nappes helvétiques en Suisse occidentale est un emblement de nappes de plis et de nappes de chaînage qui se sont mis en place à faible grade métamoiphique. Les nappes de plis et les nappes de charriage sont parmi les objets géologiques les plus communs dans les orogènes. Les nappes de plis sont des plis couchés d'échelle kilométrique caractérisés par un flanc normal faiblement déformé, au contraire de leur flanc inverse, intensément déformé. Les nappes de charriage, à l'inverse se caractérisent par l'absence d'un flanc inverse bien défini. Elles peuvent être définies comme des blocs de croûte terrestre qui se déplacent de manière presque rigide qui sont déplacés sub-horizontalement jusqu'à plusieurs dizaines de kilomètres. La nappe de Morcles and la nappe du Doldenhorn sont des exemples classiques de nappes de plis et constitue le complexe infra-helvétique en Suisse occidentale et centrale, respectivement. Ce complexe repose sous des nappes de charriages telles les nappes des Diablerets et du Widlhörn en Suisse occidentale. La nappe du Glarüs en Suisse centrale est certainement l'exemple de nappe de charriage le plus célèbre au monde. Elle se distingue par un déplacement de plus de 35 kilomètres qui s'est effectué à la faveur d'une zone de cisaillement basale épaisse de seulement 1 mètre. La géométrie et la cinématique des nappes alpines fait l'objet d'un consensus général parmi les géologues. Au contraire les processus physiques par lesquels ces nappes sont mises en place reste mal compris. Les sédiments qui forment les nappes alpines se sont déposés à l'ère secondaire et à l'ère tertiaire sur le socle de la marge européenne qui a été étiré durant l'ouverture de l'océan Téthys. Lors de la fermeture de la Téthys, qui donnera naissance aux Alpes, le socle et les sédiments de la marge européenne ont été déformés pour former les nappes alpines. Le but de cette thèse était de développer et d'appliquer des modèles basés sur la théorie de la mécanique des milieux continus et sur les transferts de chaleur pour comprendre l'emplacement des nappes. Ces modèles ont été solutionnés de manière analytique ou numérique. Dans les deux premiers articles présentés dans ce mémoire nous nous sommes intéressés à la localisation de la déformation à l'échelle d'une nappe. Nous avons appliqué le modèle développé à la nappe de Morcles et à plusieurs zones de cisaillement provenant de différents orogènes à travers le monde. Dans le dernier article nous avons étudié la relation entre la déformation du socle et la défonnation des sédiments. Nous avons démontré que nappe de plis et nappes de charriages constituent les cas extrêmes d'un continuum. La transition entre nappe de pli et nappe de charriage est intrinsèquement lié à la déformation du socle sur lequel les sédiments reposent.
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One of the key emphases of these three essays is to provide practical managerial insight. However, good practical insight, can only be created by grounding it firmly on theoretical and empirical research. Practical experience-based understanding without theoretical grounding remains tacit and cannot be easily disseminated. Theoretical understanding without links to real life remains sterile. My studies aim to increase the understanding of how radical innovation could be generated at large established firms and how it can have an impact on business performance as most businesses pursue innovation with one prime objective: value creation. My studies focus on large established firms with sales revenue exceeding USD $ 1 billion. Usually large established firms cannot rely on informal ways of management, as these firms tend to be multinational businesses operating with subsidiaries, offices, or production facilities in more than one country. I. Internal and External Determinants of Corporate Venture Capital Investment The goal of this chapter is to focus on CVC as one of the mechanisms available for established firms to source new ideas that can be exploited. We explore the internal and external determinants under which established firms engage in CVC to source new knowledge through investment in startups. We attempt to make scholars and managers aware of the forces that influence CVC activity by providing findings and insights to facilitate the strategic management of CVC. There are research opportunities to further understand the CVC phenomenon. Why do companies engage in CVC? What motivates them to continue "playing the game" and keep their active CVC investment status. The study examines CVC investment activity, and the importance of understanding the influential factors that make a firm decide to engage in CVC. The main question is: How do established firms' CVC programs adapt to changing internal conditions and external environments. Adaptation typically involves learning from exploratory endeavors, which enable companies to transform the ways they compete (Guth & Ginsberg, 1990). Our study extends the current stream of research on CVC. It aims to contribute to the literature by providing an extensive comparison of internal and external determinants leading to CVC investment activity. To our knowledge, this is the first study to examine the influence of internal and external determinants on CVC activity throughout specific expansion and contraction periods determined by structural breaks occurring between 1985 to 2008. Our econometric analysis indicates a strong and significant positive association between CVC activity and R&D, cash flow availability and environmental financial market conditions, as well as a significant negative association between sales growth and the decision to engage into CVC. The analysis of this study reveals that CVC investment is highly volatile, as demonstrated by dramatic fluctuations in CVC investment activity over the past decades. When analyzing the overall cyclical CVC period from 1985 to 2008 the results of our study suggest that CVC activity has a pattern influenced by financial factors such as the level of R&D, free cash flow, lack of sales growth, and external conditions of the economy, with the NASDAQ price index as the most significant variable influencing CVC during this period. II. Contribution of CVC and its Interaction with R&D to Value Creation The second essay takes into account the demands of corporate executives and shareholders regarding business performance and value creation justifications for investments in innovation. Billions of dollars are invested in CVC and R&D. However there is little evidence that CVC and its interaction with R&D create value. Firms operating in dynamic business sectors seek to innovate to create the value demanded by changing market conditions, consumer preferences, and competitive offerings. Consequently, firms operating in such business sectors put a premium on finding new, sustainable and competitive value propositions. CVC and R&D can help them in this challenge. Dushnitsky and Lenox (2006) presented evidence that CVC investment is associated with value creation. However, studies have shown that the most innovative firms do not necessarily benefit from innovation. For instance Oyon (2007) indicated that between 1995 and 2005 the most innovative automotive companies did not obtain adequate rewards for shareholders. The interaction between CVC and R&D has generated much debate in the CVC literature. Some researchers see them as substitutes suggesting that firms have to choose between CVC and R&D (Hellmann, 2002), while others expect them to be complementary (Chesbrough & Tucci, 2004). This study explores the interaction that CVC and R&D have on value creation. This essay examines the impact of CVC and R&D on value creation over sixteen years across six business sectors and different geographical regions. Our findings suggest that the effect of CVC and its interaction with R&D on value creation is positive and significant. In dynamic business sectors technologies rapidly relinquish obsolete, consequently firms operating in such business sectors need to continuously develop new sources of value creation (Eisenhardt & Martin, 2000; Qualls, Olshavsky, & Michaels, 1981). We conclude that in order to impact value creation, firms operating in business sectors such as Engineering & Business Services, and Information Communication & Technology ought to consider CVC as a vital element of their innovation strategy. Moreover, regarding the CVC and R&D interaction effect, our findings suggest that R&D and CVC are complementary to value creation hence firms in certain business sectors can be better off supporting both R&D and CVC simultaneously to increase the probability of generating value creation. III. MCS and Organizational Structures for Radical Innovation Incremental innovation is necessary for continuous improvement but it does not provide a sustainable permanent source of competitiveness (Cooper, 2003). On the other hand, radical innovation pursuing new technologies and new market frontiers can generate new platforms for growth providing firms with competitive advantages and high economic margin rents (Duchesneau et al., 1979; Markides & Geroski, 2005; O'Connor & DeMartino, 2006; Utterback, 1994). Interestingly, not all companies distinguish between incremental and radical innovation, and more importantly firms that manage innovation through a one-sizefits- all process can almost guarantee a sub-optimization of certain systems and resources (Davila et al., 2006). Moreover, we conducted research on the utilization of MCS along with radical innovation and flexible organizational structures as these have been associated with firm growth (Cooper, 2003; Davila & Foster, 2005, 2007; Markides & Geroski, 2005; O'Connor & DeMartino, 2006). Davila et al. (2009) identified research opportunities for innovation management and provided a list of pending issues: How do companies manage the process of radical and incremental innovation? What are the performance measures companies use to manage radical ideas and how do they select them? The fundamental objective of this paper is to address the following research question: What are the processes, MCS, and organizational structures for generating radical innovation? Moreover, in recent years, research on innovation management has been conducted mainly at either the firm level (Birkinshaw, Hamel, & Mol, 2008a) or at the project level examining appropriate management techniques associated with high levels of uncertainty (Burgelman & Sayles, 1988; Dougherty & Heller, 1994; Jelinek & Schoonhoven, 1993; Kanter, North, Bernstein, & Williamson, 1990; Leifer et al., 2000). Therefore, we embarked on a novel process-related research framework to observe the process stages, MCS, and organizational structures that can generate radical innovation. This article is based on a case study at Alcan Engineered Products, a division of a multinational company provider of lightweight material solutions. Our observations suggest that incremental and radical innovation should be managed through different processes, MCS and organizational structures that ought to be activated and adapted contingent to the type of innovation that is being pursued (i.e. incremental or radical innovation). More importantly, we conclude that radical can be generated in a systematic way through enablers such as processes, MCS, and organizational structures. This is in line with the findings of Jelinek and Schoonhoven (1993) and Davila et al. (2006; 2007) who show that innovative firms have institutionalized mechanisms, arguing that radical innovation cannot occur in an organic environment where flexibility and consensus are the main managerial mechanisms. They rather argue that radical innovation requires a clear organizational structure and formal MCS.
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The indication for pulmonary artery banding is currently limited by several factors. Previous attempts have failed to produce adjustable pulmonary artery banding with reliable external regulation. An implantable, telemetrically controlled, battery-free device (FloWatch) developed by EndoArt SA, a medical company established in Lausanne, Switzerland, for externally adjustable pulmonary artery banding was evaluated on minipigs and proved to be effective for up to 6 months. The first human implant was performed on a girl with complete atrioventricular septal defect with unbalanced ventricles, large patent ductus arteriosus and pulmonary hypertension. At one month of age she underwent closure of the patent ductus arteriosus and FloWatch implantation around the pulmonary artery through conventional left thoracotomy. The surgical procedure was rapid and uneventful. During the entire postoperative period bedside adjustments (narrowing or release of pulmonary artery banding with echocardiographic assessment) were repeatedly required to maintain an adequate pressure gradient. The early clinical results demonstrated the clinical benefits of unlimited external telemetric adjustments. The next step will be a multi-centre clinical trial to confirm the early results and adapt therapeutic strategies to this promising technology.
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Essential hypertension is a multifactorial disorder and is the main risk factor for renal and cardiovascular complications. The research on the genetics of hypertension has been frustrated by the small predictive value of the discovered genetic variants. The HYPERGENES Project investigated associations between genetic variants and essential hypertension pursuing a 2-stage study by recruiting cases and controls from extensively characterized cohorts recruited over many years in different European regions. The discovery phase consisted of 1865 cases and 1750 controls genotyped with 1M Illumina array. Best hits were followed up in a validation panel of 1385 cases and 1246 controls that were genotyped with a custom array of 14 055 markers. We identified a new hypertension susceptibility locus (rs3918226) in the promoter region of the endothelial NO synthase gene (odds ratio: 1.54 [95% CI: 1.37-1.73]; combined P=2.58 · 10(-13)). A meta-analysis, using other in silico/de novo genotyping data for a total of 21 714 subjects, resulted in an overall odds ratio of 1.34 (95% CI: 1.25-1.44; P=1.032 · 10(-14)). The quantitative analysis on a population-based sample revealed an effect size of 1.91 (95% CI: 0.16-3.66) for systolic and 1.40 (95% CI: 0.25-2.55) for diastolic blood pressure. We identified in silico a potential binding site for ETS transcription factors directly next to rs3918226, suggesting a potential modulation of endothelial NO synthase expression. Biological evidence links endothelial NO synthase with hypertension, because it is a critical mediator of cardiovascular homeostasis and blood pressure control via vascular tone regulation. This finding supports the hypothesis that there may be a causal genetic variation at this locus.
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Endoscopy constitutes an important investigation in the presence of a gastro-oesophageal reflux. The primary intention is to exclude the possibility of an organic pathology, for example cancer, which has not been demonstrated by other investigative procedures. Accordingly it must provide a detailed exploration of the whole superior digestive tract, from the mouth to the duodenum. Secondly, endoscopy must establish the consequence of the reflux on the mucosa of the lower oesophagus both by a macroscopic and a detailed microscopic description. Peptic lesions are classified according to 4 degrees of severity. The difficulty in evaluating the very early lesions (1st degree) and the advanced stages (4th degree) necessitates systematic biopsies of the lesions. The erythroplasic type of carcinoma in situ can present the same endoscopic changes as a 1st degree peptic lesion, whereas the exclusion of an adenocarcinoma constitutes the major preoccupation at the time of endoscopy of a 4th degree oesophagitis.
'Toxic' and 'Nontoxic': confirming critical terminology concepts and context for clear communication
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If 'the dose makes the poison', and if the context of an exposure to a hazard shapes the risk as much as the innate character of the hazard itself, then what is 'toxic' and what is 'nontoxic'? This article is intended to help readers and communicators: anticipate that concepts such as 'toxic' and 'nontoxic' may have different meanings to different stakeholders in different contexts of general use, commerce, science, and the law; recognize specific situations in which terms and related information could potentially be misperceived or misinterpreted; evaluate the relevance, reliability, and other attributes of information for a given situation; control actions, assumptions, interpretations, conclusions, and decisions to avoid flaws and achieve a desired outcome; and confirm that the desired outcome has been achieved. To meet those objectives, we provide some examples of differing toxicology terminology concepts and contexts; a comprehensive decision-making framework for understanding and managing risk; along with a communication and education message and audience-planning matrix to support the involvement of all relevant stakeholders; a set of CLEAR-communication assessment criteria for use by both readers and communicators; example flaws in decision-making; a suite of three tools to assign relevance vs reliability, align know vs show, and refine perception vs reality aspects of information; and four steps to foster effective community involvement and support. The framework and supporting process are generally applicable to meeting any objective.
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Considerable progress has been made in identifying the targets of plant microRNAs, many of which regulate the stability or translation of mRNAs that encode transcription factors involved in development. In most cases, it is unknown, however, which immediate transcriptional targets mediate downstream effects of the microRNA-regulated transcription factors. We identified a new process controlled by the miR319-regulated clade of TCP (TEOSINTE BRANCHED/CYCLOIDEA/PCF) transcription factor genes. In contrast to other miRNA targets, several of which modulate hormone responses, TCPs control biosynthesis of the hormone jasmonic acid. Furthermore, we demonstrate a previously unrecognized effect of TCPs on leaf senescence, a process in which jasmonic acid has been proposed to be a critical regulator. We propose that miR319-controlled TCP transcription factors coordinate two sequential processes in leaf development: leaf growth, which they negatively regulate, and leaf senescence, which they positively regulate.
Contribution of the gap junction proteins Connexin40 and Connexin43 to the control of blood pressure
Resumo:
Summary Cells in tissues and organs coordinate their activities by communicating with each other through intercellular channels named gap junctions. These channels are conduits between the cytoplasmic compartments of adjacent cells, allowing the exchange of small molecules which may be crucial for hormone secretion. Renin is normally secreted in a regulated manner by specific cells of the juxtaglomerular apparatus located within the renal cortex. Gap junctional communication may be requisite to maintain an accurate functioning in coordination of renin-producing cells, more especially as renin is of paramount importance for the control of blood pressure. Connexin43 (Cx43) and Cx40 form gap junctions that link in vivo the cells of the juxtaglomerular apparatus. Cx43 links the endothelial cells, whereas gap junctions made of Cx40 connect the endothelial cells, the renin secreting cells, as well as the endothelial cells of to the renin-secreting cells of the afferent arteriole. The observation that loss of Cx40 results in chronic hypertension associated with altered vasomotion and signal conduction along arterioles, has lead us to suggest that connexins may contribute to control blood pressure by participating to the integration of various mechanical, osmotic and electrochemical stimuli involved in the control of renin secretion and by mediating the adaptive changes of the vascular wall induced by elevated blood pressure and mechanical stress. We therefore postulated that the absence of Cx40 could have deleterious effects on the coordinated functioning of the renin-containing cells, hence accounting for hypertension. In the first part of my thesis, we reported that Cx40-deficient mice (Cx40) are hypertensive due to increased plasma renin levels and numbers of renin-producing cells. Besides, we demonstrated that prostaglandins and nitric oxide, which are possible mediators in the regulation of renin secretion by the macula densa, exert a critical role in the mechanisms controlling blood pressure ín Cx40 knockout hypertensive mice. In view of previous studies that stated avessel-specifc increase in the expression of Cx43 during renin-dependent hypertension, we hypothesized that Cx43 channels are particularly well-matched to integrate the response of cells constituting the vascular wall to hypertensive conditions. Using transgenic mice in which Cx43 was replaced by Cx32, we revealed that the replacement of Cx43 by Cx32 is associated with decreased expression and secretion of renin and prevent the renin-dependent hypertension which is normally induced in the 2K1C model. To gain insights into the regulation of connexins in two separate tissues exposed to the same fluid pressure, the second part of my thesis work was dedicated to the study of the impact of chronic hypertension and related hypertrophy on the expression of the cardiovascular connexins (Cx40, Cx37, Cx43 and Cx45) in mouse aorta and heart. Our results documented that the expression of connexins is differentially regulated in mouse aorta. according to the models of hypertension. Thus, blood pressure induces mechanical forces that differentially alter the expression of vascular connexins in order to respond to an adaptation of the aortic wall observed under pathological conditions. Altogether these data provide the first evidences that intercellular communication mediated by gap junctions is required for a proper renin secretion from the juxtaglomerular apparatus in order to control blood pressure.
Resumo:
BACKGROUND: Expression of heterologous genes in mammalian cells or organisms for therapeutic or experimental purposes often requires tight control of transgene expression. Specifically, the following criteria should be met: no background gene activity in the off-state, high gene expression in the on-state, regulated expression over an extended period, and multiple switching between on- and off-states. METHODS: Here, we describe a genetic switch system for controlled transgene transcription using chimeric repressor and activator proteins functioning in a novel regulatory network. In the off-state, the target transgene is actively silenced by a chimeric protein consisting of multimerized eukaryotic transcriptional repression domains fused to the DNA-binding tetracycline repressor. In the on-state, the inducer drug doxycycline affects both the derepression of the target gene promoter and activation by the GAL4-VP16 transactivator, which in turn is under the control of an autoregulatory feedback loop. RESULTS: The hallmark of this new system is the efficient transgene silencing in the off-state, as demonstrated by the tightly controlled expression of the highly cytotoxic diphtheria toxin A gene. Addition of the inducer drug allows robust activation of transgene expression. In stably transfected cells, this control is still observed after months of repeated cycling between the repressed and activated states of the target genes. CONCLUSIONS: This system permits tight long-term regulation when stably introduced into cell lines. The underlying principles of this network system should have general applications in biotechnology and gene therapy.
Resumo:
This article analyses the varying influence across time of the "epistemic community" of free-market economists on immigration policy making in Switzerland. To this end, a framework for the analysis of the impact of economic expertise is provided, and then used in an historical analysis comparing the 1960s with the 1990s. Whereas this influence can be considered to have been weak in the 1960s, it gained significantly in importance in the 1990s, when a period of economic unrest seriously challenged previous immigration policies. It is argued that economic experts played an important role in framing the reforms undertaken during this latter period, notably by providing a "credible causal story" about the links between the existing immigration policy and the social problems which arose in the country in the 1990s. As compared to the 1960s, economic expertise in the 1990s enjoyed more credibility, more political support and took full advantage of a more uncertain social and economic context
Resumo:
Critical size at which metamorphosis is initiated represents an important checkpoint in insect development. Here, we use experimental evolution in Drosophila melanogaster to test the long-standing hypothesis that larval malnutrition should favour a smaller critical size. We report that six fly populations subject to 112 generations of laboratory natural selection on an extremely poor larval food evolved an 18% smaller critical size (compared to six unselected control populations). Thus, even though critical size is not plastic with respect to nutrition, smaller critical size can evolve as an adaptation to nutritional stress. We also demonstrate that this reduction in critical size (rather than differences in growth rate) mediates a trade-off in body weight that the selected populations experience on standard food, on which they show a 15-17% smaller adult body weight. This illustrates how developmental mechanisms that control life history may shape constraints and trade-offs in life history evolution.
Resumo:
Brown adipocytes oxidize fatty acids to produce heat in response to cold or to excessive energy intake; stimulation of brown fat development and function may thus counteract obesity. Brown adipogenesis requires activation of the transcription factor C/EBPβ and recruitment of the zinc finger protein Prdm16, but upstream inducers of these proteins are incompletely defined. Here, we show that genetic inactivation of Plac8, a gene encoding an evolutionarily conserved protein, induces cold intolerance, and late-onset obesity, as well as abnormal morphology and impaired function of brown adipocytes. Using brown preadipocyte lines we show that Plac8 is required for brown fat differentiation, that its overexpression induces C/EBPβ and Prdm16, and that upon induction of differentiation Plac8 associates with C/EBPβ and binds to the C/EBPβ promoter to induce its transcription. Thus, Plac8 is a critical upstream regulator of brown fat differentiation and function that acts, at least in part, by inducing C/EBPβ expression.