Teor??a construccionista del aprendizaje en formaci??n del profesorado : perspectivas de alumnado y profesorado desde la investigaci??n cuantitativa y cualitativa

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Valoraci??n del uso de diferentes recursos virtuales en la universidad : una experiencia docente

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Variables asociadas a la cultura innovadora con TIC en escuelas rurales

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La visi??n de los profesores em??ritos sobre la universidad : un proceso de transici??n hacia la calidad

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Los smarthphones en educaci??n superior. Dise??o y validaci??n de dos instrumentos de recogida de informaci??n sobre la visi??n del alumnado

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Physico-chemical controls on phosphorus cycling in two lowland streams. Part 2 - The sediment phase

This article investigates the temporal and spatial controls on sediment-phosphorus (P) dynamics in two contrasting sub-catchments of the River Kennet, England. Suspended sediment (collected under representative flow conditions) and size-fractionated bedload (collected weekly for one year) from the Rivers Lambourn and Enborne was analysed for a range of physico-chemical determinands. Total P concentrations were highest in the most mobile fractions of sediment: suspended sediment, fine silt and clay and organic matter (mean concentrations of 1758, 1548 and 1440 mug P g(-1) dry sediment, respectively). Correlation analysis showed significant relationships between total P and total iron (n = 110), total manganese (n = 110), organic matter (n = 110) and specific surface area (n = 28) in the Lambourn (r(2) 0.71, 0.68, 0.62 and 0.52, respectively) and between total P and total iron (n = 110), total manganese (n = 110) and organic matter (n = 110) in the Enborne (r(2) 0.74, 0.85 and 0.68, respectively). These data highlight the importance of metal oxyhydroxide adsorption of P on fine particulates and organic matter. However, high total P concentrations in the granule gravel and coarse sand size fraction during the summer period (mean concentration 228 mug P g(-1) dry sediment) also highlight the role of calcite co-precipitation on P dynamics in the Lambourn. P to cation ratios in Lambourn sediment indicated that fine silt and clay and granule gravel and coarse sand size fractions were potential sources of P release to the water column during specific periods of the summer and autumn. In the Enborne, however, only the granule gravel and coarse sand size fraction had high ratios and a slow, constant release of P was observed. In addition, scanning electron microscopy work confirmed the association of P with calcite in the Lambourn and P with iron on clay particles in the Enborne. The study highlighted the importance of the chemical and physical properties of the sediment in influencing the mechanisms controlling P storage and release within river channels. (C) 2004 Elsevier B.V. All rights reserved.

Crystal structure of (isothiocyanato)(2-pyridinecarboxaldehydebenzoylhydrazonato)copper(I),Cu(C13H10N3O)(NCS)

C14H10CuN4OS, monoclinic, P12(1)/nl (no. 14), a = 8.837(1) angstrom, b = 15.625(2) angstrom, c = 10.366(1) angstrom, beta = 103.36(1)degrees, V = 1392.6 angstrom(3), Z = 4, R-gt(F) = 0.029, WRref(F-2) = 0.076, T = 150 K.

Geometrical isomers of [TEAH][Co(L-Se)(2)]center dot xH(2)O: synthesis, structural, spectroscopic and computational studies

Trans-1, [HNEt3][Co-III(L-Se)(2)]center dot H2O and cis-1, [HNEt3][Co-III(L-Se)(2)]center dot 3H(2)O have been synthesized and characterized by single-crystal X-ray studies. The counter ion Et3NH+ plays a crucial role in the crystal packing leading to the formation of two distinctly different supramolecular assemblies in the two complexes. In trans-1, Co-bisphenolate units and triethylamine molecules are arranged in a linear fashion leading to a supramolecular columnar assembly along the crystallographic a-axis. In this assembly, triethylammonium ions are sandwiched between successive Co-bisphenolate units and act as gluing agents joining Co-bisphenolate units on either side through C-H center dot center dot center dot pi interactions. In sharp contrast to trans-1, Co-bisphenolate units and triethylammonium ions in cis-1 are arranged in a helical supramolecular assembly through similar C-H center dot center dot center dot pi interactions along the crystallographic b-axis. The Se center dot center dot center dot Se van der Waals interactions may be responsible for the predominant occurrence of the cis-isomer. The cyclic voltammetric studies showed quasi-reversible waves for the cobalt(III) -> cobalt(II) reductions with E-1/2 = 0.635 and 0.628 V vs. Ag/AgCl for cis-1 (at similar to 5 degrees C) and trans-1 (at similar to 25 degrees C), respectively. DFT calculations show that the trans-form is the thermodynamic product with higher stability than the cis-one, which is consistent with the variable temperature H-1 NMR studies

Crystal structure of (2-pyridinecarboxaldehydeisonicotinoyl-hydrazonato)copper(I) thiocyanate, [Cu(C12H9N4O)]NCS

C13H9CuN5OS, monoclinic, P12(1)/c1 (no. 14), a = 9.900(2) angstrom, b = 11.018(1) angstrom, c = 12.861(2) angstrom, beta = 103.55(1)degrees, V = 1363.8 angstrom(3), Z = 4, R-gt(F) = 0.029, wR(ref)(F-2) = 0.088, T = 150 K.

Cannabinoid influences on palatability: microstructural analysis of sucrose drinking after Delta(9)-tetrahydrocannabinol, anandamide, 2-arachidonoyl glycerol and SR141716

Rationale: Central cannabinoid systems have been implicated in appetite control through the respective hyperphagic and anorectic actions of CB1 agonists and antagonists. The motivational changes underlying these actions remain to be determined, but may involve alterations to food palatability. Objectives: The mode of action of cannabinoids on ingestion was investigated by examining the effects of exogenous and endogenous agonists, and a selective CB1 receptor antagonist, on licking microstructure in rats ingesting a palatable sucrose solution. Methods: Microstructural analyses of licking for a 10% sucrose solution was performed over a range of agonist and antagonist doses administered to non-deprived, male Lister hooded rats. Results: Delta(9)-tetrahydrocannabinol (0.5, 1 and 3 mg/kg) and anandamide (1 mg/kg and 3 mg/kg) significantly increased total number of licks. This was primarily due to an increase in bout duration rather than bout number. There was a nonsignificant increase in total licks following administration of 2-arachidonoyl glycerol (0.2, 1.0 and 2.0 mg/kg), whereas administration of the CB1 antagonist SR141716 (1 mg/kg and 3 mg/kg) significantly decreased total licks. All drugs, with the exception of anandamide, significantly decreased the intra-bout lick rate. An exponential function fitted to the cumulative lick rate curves for each drug revealed that all compounds altered the asymptote of this function without having any marked effects on the exponent. Conclusions: These data are consistent with endocannabinoid involvement in the mediation of food palatability.

Caracterização clínico-epidemiológica do dengue grave em crianças e adolescentesRio de Janeiro, 2007-2008

Em 2007-2008, o Rio de Janeiro viveu uma epidemia de dengue com 80.404 notificações, com 109 óbitos, 42% em < 15 anos. Objetivos: 1. Descrever a distribuição espacial e o perfil clínico-epidemiológico da epidemia de dengue por faixa etária no município do Rio de Janeiro. 2. Avaliar os fatores clínicos e laboratoriais preditivos de dengue grave em uma coorte de crianças internadas. Métodos: Esta tese foi formatada com dois artigos: 1) Distribuição espacial e caracterização clínico-epidemiológico do dengue no município do Rio de Janeiro; 2) Sinais clínicos e laboratoriais associados ao dengue grave em crianças hospitalizadas. Artigo 1: estudo ecológico com base no Sistema de Informação de Agravos de Notificação do município do Rio de Janeiro (2007-2008). Foram incluídos todos os casos de dengue confirmados pelo critério clínico-laboratorial dos residentes do município do Rio de Janeiro. Foram descritas as variáveis sócio demográficas e clínicas (classificação do caso, hospitalização e evolução) segundo a idade. Foi utilizado o critério de classificação de caso do Ministério da Saúde de 2005 (febre do dengue, dengue com complicações e febre hemorrágica do dengue - FHD). Autocorrelação espacial das taxas de incidência, mortalidade e letalidade foi verificada pelos índices de Moran e de Geary Artigo 2: coorte retrospectiva das hospitalizações por dengue (até 18 anos) em uma unidade de referência (2007-2008). Dengue grave foi definido pelo uso de terapia de suporte avançado de vida ou óbito. Diferenças de medianas e de proporções foram avaliadas, respectivamente, pelo teste de Mann-Whitney e pelo exato de Fisher (p<0,05). Foram calculados os parâmetros de acurácia dos sinais e sintomas. Resultados: Artigo 1: De 159887 notificações, 151527 eram residentes do município do Rio de Janeiro, 38.808 preencheram os critérios de inclusão. Destes, 8897 (22,9%) tiveram complicações e 1051 (2,7%) FHD; 16.436 (42,4%) eram < 18 anos e 15.288 (39,4%) foram confirmados laboratorialmente. A letalidade foi maior em lactentes (1,4%) e nos casos de FHD (7,7%). Extravasamento plasmático foi mais comum de 2 a 11 anos. Houve autocorrelação espacial global quanto à mortalidade e letalidade e autocorrelação local para os três índices (p<0,05). Artigo 2: De 145 pacientes, 53,1% eram do sexo feminino, com mediana de idade de 8,7 anos (IIQ=7,2-11,5); 15,9% evoluíram para gravidade A duração da febre em dias foi menor no grupo grave (G: Mediana Md=3,0, IIQ= 2,0\20134,5; NG: Md=4,0, IIQ=3,0\20135,0; p=0.062). Letargia, irritabilidade, sangramento, dispneia, ausculta pulmonar alterada, derrame pleural, distensão abdominal e edema foram associados à evolução para gravidade (p<0,05). Níveis de hematócrito (p=008) e de albumina sérica (p<0,001) foram menores nos graves. Letargia apresentou Valor Preditivo Negativo (VPN) > 90%, com Valor Preditivo Positivo (VPP) de 80%. As demais variáveis com p-valor <0,05 apresentaram VPN próximo ou > 90%, com baixo VPP. Conclusão: Apesar da incidência de FHD ter sido maior entre escolares, os lactentes tiveram maior letalidade. Extravasamento plasmático foi mais frequente em escolares e pré-escolares. Sangramento, sonolência e irritabilidade na admissão hospitalar associaram-se à gravidade e o derrame cavitário obteve maior acurácia do que a hemoconcentração como sinal de extravasamento plasmático

Guanine specific binding at a DNA junction formed by d[CG(5-BrU)ACG]2 with a topoisomerase poison in the presence of Co2+Ions†,‡

The structure of the duplex d[CG(5-BrU)ACG]2 bound to 9-bromophenazine-4-carboxamide has been solved through MAD phasing at 2.0 Å resolution. It shows an unexpected and previously unreported intercalation cavity stabilized by the drug and novel binding modes of Co2+ ions at certain guanine N7 sites. For the intercalation cavity the terminal cytosine is rotated to pair with the guanine of a symmetry-related duplex to create a pseudo-Holliday junction geometry, with two such cavities linked through the minor groove interactions of the N2/N3 guanine sites at an angle of 40°, creating a quadruplex-like structure. The mode of binding of the drug is shown to be disordered, with the major conformations showing the side chain bound to the N7 position of adjacent guanines. The other end of the duplex exhibits a terminal base fraying in the presence of Co2+ ions linking symmetry-related guanines, causing the helices to intertwine through the minor groove. The stabilization of the structure by the intercalating drug shows that this class of compound may bind to DNA junctions as well as duplex DNA or to strand-nicked DNA (‘hemi-intercalated'), as in the cleavable complex. This suggests a structural basis for the dual poisoning of topoisomerase I and II enzymes by this family of drugs.

Structure of the ROC domain from the Parkinson's disease-associated leucine-rich repeat kinase 2 reveals a dimeric GTPase

Mutations in leucine-rich repeat kinase 2 (LRRK2) are the most common cause of Parkinson's disease (PD). LRRK2 contains a Ras of complex proteins (ROC) domain that may act as a GTPase to regulate its protein kinase activity. The structure of ROC and the mechanism(s) by which it regulates kinase activity are not known. Here, we report the crystal structure of the LRRK2 ROC domain in complex with GDP-Mg2+ at 2.0-Å resolution. The structure displays a dimeric fold generated by extensive domain-swapping, resulting in a pair of active sites constructed with essential functional groups contributed from both monomers. Two PD-associated pathogenic residues, R1441 and I1371, are located at the interface of two monomers and provide exquisite interactions to stabilize the ROC dimer. The structure demonstrates that loss of stabilizing forces in the ROC dimer is likely related to decreased GTPase activity resulting from mutations at these sites. Our data suggest that the ROC domain may regulate LRRK2 kinase activity as a dimer, possibly via the C-terminal of ROC (COR) domain as a molecular hinge. The structure of the LRRK2 ROC domain also represents a signature from a previously undescribed class of GTPases from complex proteins and results may provide a unique molecular target for therapeutics in PD.

Trypsin IV or mesotrypsin and p23 cleave protease-activated receptors 1 and 2 to induce inflammation and hyperalgesia

Although principally produced by the pancreas to degrade dietary proteins in the intestine, trypsins are also expressed in the nervous system and in epithelial tissues, where they have diverse actions that could be mediated by protease-activated receptors (PARs). We examined the biological actions of human trypsin IV (or mesotrypsin) and rat p23, inhibitor-resistant forms of trypsin. The zymogens trypsinogen IV and pro-p23 were expressed in Escherichia coli and purified to apparent homogeneity. Enteropeptidase cleaved both zymogens, liberating active trypsin IV and p23, which were resistant to soybean trypsin inhibitor and aprotinin. Trypsin IV cleaved N-terminal fragments of PAR(1), PAR(2), and PAR(4) at sites that would expose the tethered ligand (PAR(1) = PAR(4) > PAR(2)). Trypsin IV increased [Ca(2+)](i) in transfected cells expressing human PAR(1) and PAR(2) with similar potencies (PAR(1), 0.5 microm; PAR(2), 0.6 microm). p23 also cleaved fragments of PAR(1) and PAR(2) and signaled to cells expressing these receptors. Trypsin IV and p23 increased [Ca(2+)](i) in rat dorsal root ganglion neurons that responded to capsaicin and which thus mediate neurogenic inflammation and nociception. Intraplantar injection of trypsin IV and p23 in mice induced edema and granulocyte infiltration, which were not observed in PAR (-/-)(1)(trypsin IV) and PAR (-/-)(2) (trypsin IV and p23) mice. Trypsin IV and p23 caused thermal hyperalgesia and mechanical allodynia and hyperalgesia in mice, and these effects were absent in PAR (-/-)(2) mice but maintained in PAR (-/-)(1) mice. Thus, trypsin IV and p23 are inhibitor-resistant trypsins that can cleave and activate PARs, causing PAR(1)- and PAR(2)-dependent inflammation and PAR(2)-dependent hyperalgesia.

Gap junction-mediated spontaneous Ca(2+) waves in differentiated cholinergic SN56 cells

Neuronal gap junctions are receiving increasing attention as a physiological means of intercellular communication, yet our understanding of them is poorly developed when compared to synaptic communication. Using microfluorimetry, we demonstrate that differentiation of SN56 cells (hybridoma cells derived from murine septal neurones) leads to the spontaneous generation of Ca(2+) waves. These waves were unaffected by tetrodotoxin (1microM), but blocked by removal of extracellular Ca(2+), or addition of non-specific Ca(2+) channel inhibitors (Cd(2+) (0.1mM) or Ni(2+) (1mM)). Combined application of antagonists of NMDA receptors (AP5; 100microM), AMPA/kainate receptors (NBQX; 20microM), nicotinic AChR receptors (hexamethonium; 100microM) or inotropic purinoceptors (brilliant blue; 100nM) was also without effect. However, Ca(2+) waves were fully prevented by carbenoxolone (200microM), halothane (3mM) or niflumic acid (100microM), three structurally diverse inhibitors of gap junctions, and mRNA for connexin 36 was detected by PCR. Whole-cell patch-clamp recordings revealed spontaneous inward currents in voltage-clamped cells which we inhibited by Cd(2+), Ni(2+) or niflumic acid. Our data suggest that differentiated SN56 cells generated spontaneous Ca(2+) waves which are propagated by intercellular gap junctions. We propose that this system can be exploited conveniently for the development of neuronal gap junction modulators.