988 resultados para grid point selection


Relevância:

20.00% 20.00%

Publicador:

Resumo:

CD1d-dependent invariant Valpha14 (Valpha14i) NKT cells are innate T lymphocytes expressing a conserved semi-invariant TCR, consisting, in mice, of the invariant Valpha14-Jalpha18 TCR alpha-chain paired mostly with Vbeta8.2 and Vbeta7. The cellular requirements for thymic positive and negative selection of Valpha14i NKT cells are only partially understood. Therefore, we generated transgenic mice expressing human CD1d (hCD1d) either on thymocytes, mainly CD4+ CD8+ double positive, or on APCs, the cells implicated in the selection of Valpha14i NKT cells. In the absence of the endogenous mouse CD1d (mCD1d), the expression of hCD1d on thymocytes, but not on APCs, was sufficient to select Valpha14i NKT cells that proved functional when activated ex vivo with the Ag alpha-galactosyl ceramide. Valpha14i NKT cells selected by hCD1d on thymocytes, however, attained lower numbers than in control mice and expressed essentially Vbeta8.2. The low number of Vbeta8.2+ Valpha14i NKT cells selected by hCD1d on thymocytes was not reversed by the concomitant expression of mCD1d, which, instead, restored the development of Vbeta7+ Valpha14i NKT cells. Vbeta8.2+, but not Vbeta7+, NKT cell development was impaired in mice expressing both hCD1d on APCs and mCD1d. Taken together, our data reveal that selective CD1d expression by thymocytes is sufficient for positive selection of functional Valpha14i NKT cells and that both thymocytes and APCs may independently mediate negative selection.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The HER-2/ErbB-2 oncoprotein is overexpressed in human breast and ovarian adenocarcinomas and is clearly associated with the malignant phenotype. Although no specific ligand for this receptor has been positively identified, ErbB-2 was shown to play a central role in a network of interactions with the related ErbB-1, ErbB-3 and ErbB-4 receptors. We have selected new peptides binding to ErbB-2 extracellular domain protein (ECD) by screening 2 newly developed constrained and unconstrained random hexapeptide phage libraries. Out of 37 phage clones, which bound specifically to ErbB-2 ECD, we found 6 constrained and 10 linear different hexapeptide sequences. Among the latter, 5 consensus motifs, all with a common methionine and a positively charged residue at positions 1 and 3, respectively, were identified. Furthermore, 3 representative hexapeptides were fused to a coiled-coil pentameric recombinant protein to form the so-called peptabodies recently developed in our laboratory. The 3 peptabodies bound specifically to the ErbB-2 ECD, as determined by enzyme-linked immunosorbent assay and BIAcore analysis and to tumor cells overexpressing ErbB-2, as shown by flow cytometry. Interestingly, one of the free selected linear peptides and all 3 peptabodies inhibited the proliferation of tumor cells overexpressing ErbB-2. In conclusion, a novel type of ErbB-2-specific ligand is described that might complement presently available monoclonal antibodies.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The way an organism spreads its reproduction over time is defined as a life-history trait, and selection is expected to favour life-history traits associated with the highest fitness return. We use a long-term dataset of 277 life histories to investigate the shape and strength of selection acting on the age at first reproduction and at last reproduction in the long-lived Alpine Swift. Both traits were under strong directional selection, but in opposite directions, with selection favouring birds starting their reproductive career early and being able to reproduce for longer. There was also evidence for stabilising selection acting on both traits, suggesting that individuals should nonetheless refrain from reproducing in their first 2 years of life (i.e. when inexperienced), and that reproducing after 7 years of age had little effect on lifetime fitness, probably due to senescence.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Objective: To identify and prioritize improvement opportunities, according to the European Foundation for Quality Management model (EFQM) model, of the methadone dispensing service in Andalusian Primary Health Care, from the point of view of professionals. Method: Delphi consensus method, implemented from September 2007 to March 2008 by means of three rounds of interviews with questionnaires administered by electronic mail to 39 professionals. The Panel of experts was made up of Dispensers and Prescribers of methadone as well as Coordinators of welfare services from the Methadone Treatment Program (MTP). Selection criteria were: Being in active employment with a minimum of 3 years experience. Sample diversification variables: Professional role, geographical environment and type of habitat. Recruitment: By means of key professional bodies from different institutions. Results: 48 improvement opportunities were identified. Thirteen of these obtained a high level of agreement in the final round. According to the EFQM model, the dimensions that obtained the most consensus in relation to improving the care service were: Leadership, Alliances and Resources. The dimension that caused the greatest disagreement was Processes. Conclusions: In spite of its having been implemented since 1997 in Andalusian Primary Health Care, the methadone dispensing service is at an implementation phase, rather than what could be classed as a fully deployed stage

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Two endangered tetraonids, the capercaillie (Tetrao urogallus) and the hazel grouse (Bonasa bonasia rupestris), are sympatric throughout part of their distribution range in central Europe. Precise information on their specific habitat requirements is needed if the coexistence of both species in exploited forests is to be maintained. We quantified winter habitat selection for both species in the upper part (1100-1600 m) of the Jura mountains (Switzerland). No preference for altitude or exposure could be detected. Capercaillie preferred open forests (including grazed forests) with a sparse canopy dominated by spruce (Picea abies) and fir (Abies alba), and avoided dense undercanopy and understorey, especially when dominated by spruce and beech (Fagus sylvatica). By contrast, hazel grouse preferred feeding sites with a dense understorey of rowan (Sorbus aucuparia), willow (Salix sp.), beech and spruce. These preferences can be related to the feeding habits and predator avoidance behaviour of both species. Coexistence thus requires a mosaic distribution of habitat types, with a matrix of open forests (30% canopy cover) where fir is favoured, and understorey kept sparse (20%). Group-cuts of mature trees should allow regeneration patches, where a dense understorey (50% cover) should provide suitable habitats for hazel grouse

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Doctors must regularly adjust their patients' care according to recent relevant publications. The chief residents from the Department of Internal Medicine of a university hospital present some major themes of internal medicine treated during the year 2008, such as heart failure, diabetes, COPD, and thromboembolic disease. Emphasis will be placed primarily on changes in the daily hospital practice induced by these recent studies. This variety of topics illustrates both the broad spectrum of the current internal medicine, and the many uncertainties associated with modem medical practice based on evidence.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

L’objectiu d’aquest projecte és analitzar la qualitat literària dels best sellers i observar les limitacions d’aquest anàlisi. Deguda la complexitat del fenòmen best seller, i tot i ser conscients de que són obres que s’han d’abordar des d’una perspectiva pluridisciplinar, vam decidir començar aquest projecte analitzant tres best sellers espanyols des de la metodologia de l’estilística i de la narratologia. Les obres analitzades són 'La sombra del viento' de Carlos Ruiz Zafón, 'Un milagro en equilibrio', de Lucía Etxevarría, i 'El capitán Alatriste', de Pérez Reverte, i l’anàlisi és de tipus quantitatiu, de les estructures emprades per a l’expressió de lo metafòric, dels personatges, trames i tòpics. Les conclusions varen ser que, des d’un punt de vista estilístic, es pot demostrar la mala qualitat literària d’aquestes obres, així com la seva relació amb la tradició del gènere del folletí, amb el que comparteixen moltes característiques. Tanmateix, una altra de les conclusions de l’estudi fou que abordar el best seller des de l’estilística no ofereix una visió completa d’aquest fenòmen. Aquest projecte doncs, que té per títol “Estudio estilístico de tres casos de best seller en el ámbito español: 'La sombra del viento', 'Un milagro en equilibrio' y 'El capitán Alatriste'” ha d’ampliar-se en catàleg i en metodologia, adoptant vàries perspectives simultàneament, que ofereixin una visió adecuada de la complexitat del fenòmen. El catàleg s’ha extès a 15 obres en l’àmbit espanyol, i a 15 més en l’àmbit francès, durant el 2008, i la perspectiva multidisciplinar engloba estudis culturals, de recepció i sociologia. Des d’aquesta nova base metodològica i teòrica, s’han realitzat 500 enquestes a lectors a Barcelona i a París, en diferents punts de venta de llibres, durant el 2010.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The study investigated the development and stage specificity of physiological resistance to insecticides in a colony of Culex quinquefasciatus Say (Diptera: Culicidae) mosquitoes, which are vectors of bancroftian filariasis in India, after selection with deltamethrin. Resistance was selected by exposing the larvae to the concentration of deltamethrin that caused 50% mortality in the tested population (i.e., LC50). Under continuous selection pressure, the LC50 increased steadily in subsequent generations. The estimated LC50 for the F0 generation was 0.409 μg/L; the LC50 first displayed a substantial increase in the F5 generation (5.616 μg/L) and reached 121.902 μg/L in the F10 generation. The objective of this study was to establish a deltamethrin-resistant colony to develop a research programme that will study the evolution of physiological resistance patterns and stage-specific resistance responses in Cx. quinquefasciatus larvae and adults under laboratory conditions. An approximately 298-fold increase in resistance was recorded after 10 generations, as evidenced by the resistance ratio (RR50). The progress and effect of the selection pressure in the adult stage was monitored with the World Health Organisation (WHO) diagnostic test. The mortality, as observed using the WHO diagnostic test, declined significantly from the F5 generation (85%) onwards and the highest rate of survival (65%) was observed in the F10 generation.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

A ciprofloxacin-resistant Escherichia coli isolate, isolate 1B, was obtained from a urinary specimen of a Canadian patient treated with norfloxacin for infection due to a ciprofloxacin-susceptible isolate, isolate 1A. Both isolates harbored a plasmid-encoded sul1-type integron with qnrA1 and blaVEB-1 genes. Isolate 1B had amino acid substitutions in gyrase and topoisomerase.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Fanconi anemia (FA) is a genetically heterogeneous chromosome instability syndrome associated with congenital abnormalities, bone marrow failure, and cancer predisposition. Eight FA proteins form a nuclear core complex, which promotes tolerance of DNA lesions in S phase, but the underlying mechanisms are still elusive. We reported recently that the FA core complex protein FANCM can translocate Holliday junctions. Here we show that FANCM promotes reversal of model replication forks via concerted displacement and annealing of the nascent and parental DNA strands. Fork reversal by FANCM also occurs when the lagging strand template is partially single-stranded and bound by RPA. The combined fork reversal and branch migration activities of FANCM lead to extensive regression of model replication forks. These observations provide evidence that FANCM can remodel replication fork structures and suggest a mechanism by which FANCM could promote DNA damage tolerance in S phase