930 resultados para context cues


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Tumor necrosis factor (TNF) is a pro-inflammatory cytokine exerting pleiotropic effects on endothelial cells. Depending on the vascular context it can induce endothelial cell activation and survival or death. The microenvironmental cues determining whether endothelial cells will survive or die, however, have remained elusive. Here we report that integrin ligation acts permissive for TNF-induced protein kinase B (PKB/Akt) but not nuclear factor (NF)-kappaB activation. Concomitant activation of PKB/Akt and NF-kappaB is essential for the survival of endothelial cells exposed to TNF. Active PKB/Akt strengthens integrin-dependent endothelial cell adhesion, whereas disruption of actin stress fibers abolishes the protective effect of PKB/Akt. Integrin-mediated adhesion also represses TNF-induced JNK activation, but JNK activity is not required for cell death. The alphaVbeta3/alphaVbeta5 integrin inhibitor EMD121974 sensitizes endothelial cells to TNF-dependent cytotoxicity and active PKB/Akt attenuates this effect. Interferon gamma synergistically enhanced TNF-induced endothelial cell death in all conditions tested. Taken together, these observations reveal a novel permissive role for integrins in TNF-induced PKB/Akt activation and prevention of TNF-induced death distinct of NF-kappaB, and implicate the actin cytoskeleton in PKB/Akt-mediated cell survival. The sensitizing effect of EMD121974 on TNF cytotoxicity may open new perspectives to the therapeutic use of TNF as anticancer agent.

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Teemanumero

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Most organisms use circadian oscillators to coordinate physiological and developmental processes such as growth with predictable daily environmental changes like sunrise and sunset. The importance of such coordination is highlighted by studies showing that circadian dysfunction causes reduced fitness in bacteria and plants, as well as sleep and psychological disorders in humans. Plant cell growth requires energy and water-factors that oscillate owing to diurnal environmental changes. Indeed, two important factors controlling stem growth are the internal circadian oscillator and external light levels. However, most circadian studies have been performed in constant conditions, precluding mechanistic study of interactions between the clock and diurnal variation in the environment. Studies of stem elongation in diurnal conditions have revealed complex growth patterns, but no mechanism has been described. Here we show that the growth phase of Arabidopsis seedlings in diurnal light conditions is shifted 8-12 h relative to plants in continuous light, and we describe a mechanism underlying this environmental response. We find that the clock regulates transcript levels of two basic helix-loop-helix genes, phytochrome-interacting factor 4 (PIF4) and PIF5, whereas light regulates their protein abundance. These genes function as positive growth regulators; the coincidence of high transcript levels (by the clock) and protein accumulation (in the dark) allows them to promote plant growth at the end of the night. Thus, these two genes integrate clock and light signalling, and their coordinated regulation explains the observed diurnal growth rhythms. This interaction may serve as a paradigm for understanding how endogenous and environmental signals cooperate to control other processes.

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Eukaryotic mRNA transcription and turnover is controlled by an enzymatic machinery that includes RNA polymerase II and the 3' to 5' exosome. The activity of these protein complexes is modulated by additional factors, such as the nuclear RNA polymerase II-associated factor 1 (Paf1c) and the cytoplasmic Superkiller (SKI) complex, respectively. Their components are conserved across uni- as well as multi-cellular organisms, including yeast, Arabidopsis, and humans. Among them, SKI8 displays multiple facets on top of its cytoplasmic role in the SKI complex. For instance, nuclear yeast ScSKI8 has an additional function in meiotic recombination, whereas nuclear human hSKI8 (unlike ScSKI8) associates with Paf1c. The Arabidopsis SKI8 homolog VERNALIZATION INDEPENDENT 3 (VIP3) has been found in Paf1c as well; however, whether it also has a role in the SKI complex remains obscure so far. We found that transgenic VIP3-GFP, which complements a novel vip3 mutant allele, localizes to both nucleus and cytoplasm. Consistently, biochemical analyses suggest that VIP3-GFP associates with the SKI complex. A role of VIP3 in the turnover of nuclear encoded mRNAs is supported by random-primed RNA sequencing of wild-type and vip3 seedlings, which indicates mRNA stabilization in vip3. Another SKI subunit homolog mutant, ski2, displays a dwarf phenotype similar to vip3. However, unlike vip3, it displays neither early flowering nor flower development phenotypes, suggesting that the latter reflect VIP3's role in Paf1c. Surprisingly then, transgenic ScSKI8 rescued all aspects of the vip3 phenotype, suggesting that the dual role of SKI8 depends on species-specific cellular context.

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The present document should be seen as one more contribution to the debate to the reform processes and a small guide to these processes and their latest outcomes.

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Although canonical Notch signaling regulates multiple hematopoietic lineage decisions including T cell and marginal zone B cell fate specification, the downstream molecular mediators of Notch function are largely unknown. We showed here that conditional inactivation of Hes1, a well-characterized Notch target gene, in adult murine bone marrow (BM) cells severely impaired T cell development without affecting other Notch-dependent hematopoietic lineages such as marginal zone B cells. Competitive mixed BM chimeras, intrathymic transfer experiments, and in vitro culture of BM progenitors on Delta-like-expressing stromal cells further demonstrated that Hes1 is required for T cell lineage commitment, but dispensable for Notch-dependent thymocyte maturation through and beyond the beta selection checkpoint. Furthermore, our data strongly suggest that Hes1 is essential for the development and maintenance of Notch-induced T cell acute lymphoblastic leukemia. Collectively, our studies identify Hes1 as a critical but context-dependent mediator of canonical Notch signaling in the hematopoietic system.

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La preocupació, com a docents universitaris i professionals de l’educació, per la manca de representació masculina en l’Educació Infantil, ha determinat que el nostre grup de recerca, centrat en estudis sobre la infància, es plantegés la realització de diferents estudis descriptius sobre l’equitat de gènere en aquesta etapa educativa. El primer estudi està centrat en l’home com a professional de l’Educació Infantil, com a estudiant i com a professio· nal en actiu. El segon estudi està centrat en l’avaluació de l’equitat de gènere en la pràctica educativa a l’escola, a Catalunya. I finalment, el tercer estudi, focalitza la seva mirada en el context cultural, portant a terme un estu· di paral·lel entre les realitats educatives de Catalunya i La Paz (Bolívia). Els resultats, malgrat que es detecten petits avenços en la presència del valor de l’equitat de gènere en els centres educatius, confirmen les dificultats, existents encara, per realitzar pràctiques de qualitat que puguin incidir vers un canvi social. Considerem que aquest canvi només s’aconseguirà quan es plantegi seriosament la necessitat d’aquest valor social i es treballi no solament des de l’escola, sinó també des de dinàmiques laborals, mediàtiques, familiars i socials. Aquest article recull les reflexiones que deriven de les tres recerques esmentades.

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Multisensory processes facilitate perception of currently-presented stimuli and can likewise enhance later object recognition. Memories for objects originally encountered in a multisensory context can be more robust than those for objects encountered in an exclusively visual or auditory context [1], upturning the assumption that memory performance is best when encoding and recognition contexts remain constant [2]. Here, we used event-related potentials (ERPs) to provide the first evidence for direct links between multisensory brain activity at one point in time and subsequent object discrimination abilities. Across two experiments we found that individuals showing a benefit and those impaired during later object discrimination could be predicted by their brain responses to multisensory stimuli upon their initial encounter. These effects were observed despite the multisensory information being meaningless, task-irrelevant, and presented only once. We provide critical insights into the advantages associated with multisensory interactions; they are not limited to the processing of current stimuli, but likewise encompass the ability to determine the benefit of one's memories for object recognition in later, unisensory contexts.

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Tutkimuksen tavoitteena oli selvittää ohjelmistotoimialan avaintekijöitä, jotka vaikuttavat yrityksen ansaintalogiikkaan sekä lisätä tietoisuutta ansaintalogiikan muodostumisesta pienissä ja keskisuurissa ohjelmistoyrityksissä. Tutkimuksen teoreettisessa osassa keskityttiin tarkastelemaan ansaintalogiikan, strategian ja liiketoimintamallin käsitteiden suhteita sekä arvioitiin toimialan osatekijöiden, hinnoitteluperiaatteiden ja ansaintamallien vaikutusta ansainnan muodostumiseen ohjelmistotoimialalla. Ohjelmistotuote ja - palveluliiketoimintaa koskien oli merkityksellistä tutkia tuotteistamisasteen ja arvoketjujen vaikutusta ansaintalogiikan muodostumisessa sekä esitellä erilaisia, tyypillisiä ohjelmistotoimialalla käytettäviä hinnoittelumenetelmiä. Työn empiirisessä osassa tarkasteltiin 23 suomalaisen ohjelmistoalan yrityksen ansaintalogiikkaa. Tiedot kerättiin haastatteluin ja analysoitiin laadullisen tutkimuksen keinoin. Tutkimustulokset korostivat ansaintalogiikan 'epämääräisyyttä' terminä mutta osoittivat, että ydinliiketoimintaan keskittyminen, tuote-, palvelu-, tai projektiliiketoiminnan osaaminen, tuotteistusaste ja kanavavalinnat ovat avaintekijöitä ansaintalogiikanmuodostumisessa. Ansaintalogiikan muodostamiseen liittyy paljon yrityksen sisäisiä ja ulkoisia haasteita sekä muutospaineita, eikä ohjelmistotoimialalla ole todennettavissa yhtä yleismaailmallista, menestyksen takaavaa ansaintalogiikkaa.

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Tämän Pro gradu-tutkielman tavoitteena olirakentaa esiymmärrys sosiaalisen pääoman roolista ja mittaamisesta uuden teknologian start-up yrityksissä. Pääasiallisena tarkoituksena tässä tutkimuksessa olilöytää sosiaalisen pääoman ja start-up yrityksen tuloksellisuuden välille yhdistävä tekijä. Tutkimuksen empiirinen aineisto kerättiin pääasiallisesti kuuden OKO Venture Capitalin sijoitusportfolioon sisältyvien case-yritysten kvalitatiivisten teemahaastatteluiden sekä kvantitatiivisten kyselylomakkeiden avulla. Kvalitatiivisten haastatteluiden tulosten perusteella sosiaalisen pääoman ja tuloksellisuuden välille löytyi yhdistävä tekijä, jota käytettiin myöhemmin hyväksi kvantitatiivisessa kyselylomakkeessa. Tämän tutkielman tulokset osoittivat, että startegisen päätöksenteon kautta sosiaalinen pääoma vaikuttaa osittain start-up yritysten tuloksellisuuteen. Manageriaalisesti tärkempi löydös tässä tutkimuksessa oli kuitenkin se, että sosiaalista pääomaa voidaan käyttää hyväksi ennustettaessa uuden teknologian start-up yritysten tulevaisuuden kassavirtoja.