549 resultados para Electronic key
Resumo:
The increase of the body's capacity to transport oxygen is a prime target for doping athletes in all endurance sports. For this pupose, blood transfusions or erythropoiesis stimulating agents (ESA), such as erythropoietin, NESP, and CERA are used. As direct detection of such manipulations is difficult, biomarkers that are connected to the haematopoietic system (haemoglobin concentration, reticulocytes) are monitored over time (Athlete Biological Passport (ABP)) and analyzed using mathematical models to identify patterns suspicious of doping. With this information, athletes can either be sanctioned directly based on their profile or targeted with conventional doping tests. Key issues for the appropriate use of the ABP are correct targeting and use of all available information (e.g. whereabouts, cross sectional population data) in a forensic manner. Future developments of the passport include the correction of all concentration-based variables for shifts in plasma volume, which might considerably increase sensitivity. New passport markers from the genomic, proteomic, and metabolomic level might add further information, but need to be validated before integration into the passport procedure. A first assessment of blood data of federations that have implemented the passport show encouraging signs of a decreased blood-doping prevalence in their athletes, which adds scientific credibility to this innovative concept in the fight against ESA- and blood doping. Copyright © 2012 John Wiley & Sons, Ltd.
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The location and timing of domestication of the olive tree, a key crop in Early Mediterranean societies, remain hotly debated. Here, we unravel the history of wild olives (oleasters), and then infer the primary origins of the domesticated olive. Phylogeography and Bayesian molecular dating analyses based on plastid genome profiling of 1263 oleasters and 534 cultivated genotypes reveal three main lineages of pre-Quaternary origin. Regional hotspots of plastid diversity, species distribution modelling and macrofossils support the existence of three long-term refugia; namely the Near East (including Cyprus), the Aegean area and the Strait of Gibraltar. These ancestral wild gene pools have provided the essential foundations for cultivated olive breeding. Comparison of the geographical pattern of plastid diversity between wild and cultivated olives indicates the cradle of first domestication in the northern Levant followed by dispersals across the Mediterranean basin in parallel with the expansion of civilizations and human exchanges in this part of the world.
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Methyl-CpG Binding Domain (MBD) proteins are thought to be key molecules in the interpretation of DNA methylation signals leading to gene silencing through recruitment of chromatin remodeling complexes. In cancer, the MBD-family member, MBD2, may be primarily involved in the repression of genes exhibiting methylated CpG at their 5' end. Here we ask whether MBD2 randomly associates methylated sequences, producing chance effects on transcription, or exhibits a more specific recognition of some methylated regions. Using chromatin and DNA immunoprecipitation, we analyzed MBD2 and RNA polymerase II deposition and DNA methylation in HeLa cells on arrays representing 25,500 promoter regions. This first whole-genome mapping revealed the preferential localization of MBD2 near transcription start sites (TSSs), within the region analyzed, 7.5 kb upstream through 2.45 kb downstream of 5' transcription start sites. Probe by probe analysis correlated MBD2 deposition and DNA methylation. Motif analysis did not reveal specific sequence motifs; however, CCG and CGC sequences seem to be overrepresented. Nonrandom association (multiple correspondence analysis, p < 0.0001) between silent genes, DNA methylation and MBD2 binding was observed. The association between MBD2 binding and transcriptional repression weakened as the distance between binding site and TSS increased, suggesting that MBD2 represses transcriptional initiation. This hypothesis may represent a functional explanation for the preferential binding of MBD2 at methyl-CpG in TSS regions.
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Overexpression of the polycomb group protein enhancer of zeste homologue 2 (EZH2) occurs in diverse malignancies, including prostate cancer, breast cancer, and glioblastoma multiforme (GBM). Based on its ability to modulate transcription of key genes implicated in cell cycle control, DNA repair, and cell differentiation, EZH2 is believed to play a crucial role in tissue-specific stem cell maintenance and tumor development. Here, we show that targeted pharmacologic disruption of EZH2 by the S-adenosylhomocysteine hydrolase inhibitor 3-deazaneplanocin A (DZNep), or its specific downregulation by short hairpin RNA (shRNA), strongly impairs GBM cancer stem cell (CSC) self-renewal in vitro and tumor-initiating capacity in vivo. Using genome-wide expression analysis of DZNep-treated GBM CSCs, we found the expression of c-myc, recently reported to be essential for GBM CSCs, to be strongly repressed upon EZH2 depletion. Specific shRNA-mediated downregulation of EZH2 in combination with chromatin immunoprecipitation experiments revealed that c-myc is a direct target of EZH2 in GBM CSCs. Taken together, our observations provide evidence that direct transcriptional regulation of c-myc by EZH2 may constitute a novel mechanism underlying GBM CSC maintenance and suggest that EZH2 may be a valuable new therapeutic target for GBM management.
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Hypertension is a serious medical problem affecting millions of people worldwide. A key protein regulating blood pressure is the Epithelial Na(+) Channel (ENaC). In accord, loss of function mutations in ENaC (PHA1) cause hypotension, whereas gain of function mutations (Liddle syndrome) result in hypertension. The region mutated in Liddle syndrome, called the PY motif (L/PPxY), serves as a binding site for the ubiquitin ligase Nedd4-2, a C2-WW-Hect E3 ubiquitin ligase. Nedd4-2 binds the ENaC-PY motif via it WW domains, ubiquitylates the channel and targets it for endocytosis, a process impaired in Liddle syndrome due to poor binding of the channel to Nedd4-2. This leads to accumulation of active channels at the cell surface and increased Na(+) (and fluid) absorption in the distal nephron, resulting in elevated blood volume and blood pressure. Compounds that destabilize cell surface ENaC, or enhance Nedd4-2 activity in the kidney, could potentially serve as drug targets for hypertension. In addition, recent discoveries of regulation of activation of ENaC by proteases such as furin, prostasin and elastase, which cleave the extracellular domain of this channel leading to it activation, as well as the identification of inhibitors that block the activity of these proteases, provide further avenues for drug targeting of ENaC and the control of blood pressure.
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Understanding the drivers of population divergence, speciation and species persistence is of great interest to molecular ecology, especially for species-rich radiations inhabiting the world's biodiversity hotspots. The toolbox of population genomics holds great promise for addressing these key issues, especially if genomic data are analysed within a spatially and ecologically explicit context. We have studied the earliest stages of the divergence continuum in the Restionaceae, a species-rich and ecologically important plant family of the Cape Floristic Region (CFR) of South Africa, using the widespread CFR endemic Restio capensis (L.) H.P. Linder & C.R. Hardy as an example. We studied diverging populations of this morphotaxon for plastid DNA sequences and >14 400 nuclear DNA polymorphisms from Restriction site Associated DNA (RAD) sequencing and analysed the results jointly with spatial, climatic and phytogeographic data, using a Bayesian generalized linear mixed modelling (GLMM) approach. The results indicate that population divergence across the extreme environmental mosaic of the CFR is mostly driven by isolation by environment (IBE) rather than isolation by distance (IBD) for both neutral and non-neutral markers, consistent with genome hitchhiking or coupling effects during early stages of divergence. Mixed modelling of plastid DNA and single divergent outlier loci from a Bayesian genome scan confirmed the predominant role of climate and pointed to additional drivers of divergence, such as drift and ecological agents of selection captured by phytogeographic zones. Our study demonstrates the usefulness of population genomics for disentangling the effects of IBD and IBE along the divergence continuum often found in species radiations across heterogeneous ecological landscapes.
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PURPOSE OF REVIEW: The mechanisms involved in the formation of red blood cell (RBC) microparticles in vivo as well as during erythrocyte storage are reviewed, and the potential role of microparticles in transfusion medicine is described. RECENT FINDINGS: Microparticles release is an integral part of the erythrocyte ageing process, preventing early removal of RBCs. Proteomics analyses have outlined the key role of band 3-ankyrin anchoring complex and the occurrence of selective RBC membrane remodelling mechanisms in microparticles formation. The presence of several RBC antigens, expressed on microparticles, has been demonstrated. The potential deleterious effects of RBC microparticles in transfused recipients, including hypercoagulability, microcirculation impairment and immunosuppression, are discussed. SUMMARY: Formation and role of RBC microparticles are far from being completely understood. Combining various approaches to elucidate these mechanisms could improve blood product quality and transfusion safety. Implementation of RBC microparticles as biomarkers in the laboratory routine needs to overcome technical barriers involved in their analysis.
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Pachydermoperiostosis, or primary hypertrophic osteoarthropathy (PHO), is an inherited multisystem disorder, whose features closely mimic the reactive osteoarthropathy that commonly accompanies neoplastic and inflammatory pathologies. We previously described deficiency of the prostaglandin-degrading enzyme 15-hydroxyprostaglandin dehydrogenase (HPGD) as a cause of this condition, implicating elevated circulating prostaglandin E(2) (PGE(2) ) as causative of PHO, and perhaps also as the principal mediator of secondary HO. However, PHO is genetically heterogeneous. Here, we use whole-exome sequencing to identify recessive mutations of the prostaglandin transporter SLCO2A1, in individuals lacking HPGD mutations. We performed exome sequencing of four probands with severe PHO, followed by conventional mutation analysis of SLCO2A1 in nine others. Biallelic SLCO2A1 mutations were identified in 12 of the 13 families. Affected individuals had elevated urinary PGE(2) , but unlike HPGD-deficient patients, also excreted considerable quantities of the PGE(2) metabolite, PGE-M. Clinical differences between the two groups were also identified, notably that SLCO2A1-deficient individuals have a high frequency of severe anemia due to myelofibrosis. These findings reinforce the key role of systemic or local prostaglandin excess as the stimulus to HO. They also suggest that the induction or maintenance of hematopoietic stem cells by prostaglandin may depend upon transporter activity. Hum Mutat 33:1175-1181, 2012. © 2012 Wiley Periodicals, Inc.
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Relatively, few species have been able to colonize extremely cold alpine environments. We investigate the role played by the cushion life form in the evolution of climatic niches in the plant genus Androsace s.l., which spreads across the mountain ranges of the Northern Hemisphere. Using robust methods that account for phylogenetic uncertainty, intraspecific variability of climatic requirements and different life-history evolution scenarios, we show that climatic niches of Androsace s.l. exhibit low phylogenetic signal and that they evolved relatively recently and punctually. Models of niche evolution fitted onto phylogenies show that the cushion life form has been a key innovation providing the opportunity to occupy extremely cold environments, thus contributing to rapid climatic niche diversification in the genus Androsace s.l. We then propose a plausible scenario for the adaptation of plants to alpine habitats.
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As a result of recent welfare state transformations, and most notably the reorientation of welfare states towards activation, the internal fragmentation of social security systems has emerged as a key policy problem in many western European countries. The types of response that have been adopted, however, vary substantially across countries, ranging from the encouragement of inter-agency collaboration to the outright merger of agencies. The purpose of this exploratory article is twofold. First, by proposing the concept of coordination initiatives, it tries to develop a better conceptualization of the cross-national diversity in responses to the fragmentation problem. Second, starting from existing theories of welfare state development and policy change, it presents first hypotheses accounting for the variation observed in coordination initiatives.
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Canonical Wnt signaling plays a critical role in stem cell maintenance in epithelial homeostasis and carcinogenesis. Here, we show that in the mouse this role is critically mediated by Bcl9/Bcl9l, the mammalian homologues of Legless, which in Drosophila is required for Armadillo/beta-catenin signaling. Conditional ablation of Bcl9/Bcl9l in the intestinal epithelium, where the essential role of Wnt signaling in epithelial homeostasis and stem cell maintenance is well documented, resulted in decreased expression of intestinal stem cell markers and impaired regeneration of ulcerated colon epithelium. Adenocarcinomas with aberrant Wnt signaling arose with similar incidence in wild-type and mutant mice. However, transcriptional profiles were vastly different: Whereas wild-type tumors displayed characteristics of epithelial-mesenchymal transition (EMT) and stem cell-like properties, these properties were largely abrogated in mutant tumors. These findings reveal an essential role for Bcl9/Bcl9l in regulating a subset of Wnt target genes involved in controlling EMT and stem cell-related features and suggest that targeting the Bcl9/Bcl9l arm of Wnt signaling in Wnt-activated cancers might attenuate these traits, which are associated with tumor invasion, metastasis, and resistance to therapy.
Resumo:
BACKGROUND & AIMS: Recently, genetic variations in MICA (lead single nucleotide polymorphism [SNP] rs2596542) were identified by a genome-wide association study (GWAS) to be associated with hepatitis C virus (HCV)-related hepatocellular carcinoma (HCC) in Japanese patients. In the present study, we sought to determine whether this SNP is predictive of HCC development in the Caucasian population as well. METHODS: An extended region around rs2596542 was genotyped in 1924 HCV-infected patients from the Swiss Hepatitis C Cohort Study (SCCS). Pair-wise correlation between key SNPs was calculated both in the Japanese and European populations (HapMap3: CEU and JPT). RESULTS: To our surprise, the minor allele A of rs2596542 in proximity of MICA appeared to have a protective impact on HCC development in Caucasians, which represents an inverse association as compared to the one observed in the Japanese population. Detailed fine-mapping analyses revealed a new SNP in HCP5 (rs2244546) upstream of MICA as strong predictor of HCV-related HCC in the SCCS (univariable p=0.027; multivariable p=0.0002, odds ratio=3.96, 95% confidence interval=1.90-8.27). This newly identified SNP had a similarly directed effect on HCC in both Caucasian and Japanese populations, suggesting that rs2244546 may better tag a putative true variant than the originally identified SNPs. CONCLUSIONS: Our data confirms the MICA/HCP5 region as susceptibility locus for HCV-related HCC and identifies rs2244546 in HCP5 as a novel tagging SNP. In addition, our data exemplify the need for conducting meta-analyses of cohorts of different ethnicities in order to fine map GWAS signals.
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The outcome for patients after an out-of-hospital cardiac arrest (OHCA) has been poor over many decades and single interventions have mostly resulted in disappointing results. More recently, some regions have observed better outcomes after redesigning their cardiac arrest pathways. Optimised resuscitation and prehospital care is absolutely key, but in-hospital care appears to be at least as important. OHCA treatment requires a multidisciplinary approach, comparable to trauma care; the development of cardiac arrest pathways and cardiac arrest centres may dramatically improve patient care and outcomes. Besides emergency medicine physicians, intensivists and neurologists, cardiologists are playing an increasingly crucial role in the post-resuscitation management, especially by optimising cardiac output and undertaking urgent coronary angiography/intervention.