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Versión definitiva Aprendiendo a trabajar en conjunto
No full textEsta tesis destaca una experiencia de formación no canónica cuyo objetivo ha sido desarrollar competencias profesionales a las que suele darse máxima importancia pero de cuyos procesos se conoce poco (p. ej. la colaboración). Se exponen los resultados obtenidos del Laboratorio de mejora de prácticas escolares realizado entre agosto 2011 y junio 2012 con docentes de una escuela preparatoria en el Estado de México. El estudio, posicionado desde la psicología cultural de las organizaciones y la teoría de la actividad, es relevante porque describe y analiza cómo una experiencia divergente de formación provee una herramienta y soporte para el aprendizaje en el propio contexto laboral. Los datos señalan fortalecimiento de la identidad docente y por ende, de la comunidad profesional. El estudio tiene implicaciones para operativizar con rigurosidad procesos de aprendizaje situado a través de un soporte sistemático. Los datos son útiles para proyectar experiencias de formación en apego a la metodología de la investigación-intervención propuesta por la teoría de la actividad. Se desentrañan factores contextuales en función de una organización escolar poco explorada (una escuela del nivel medio superior). La estructura contemporánea de las escuelas preparatorias, los cambios organizativos y de gestión que implica la reforma escolar en curso, así como la prevalencia de un modelo de formación docente tradicional, enfatizan conceptualizar a la escuela como sistema de actividad, reconociendo el aprendizaje en el contexto. Este trabajo aporta a la construcción de una óptica colectiva de la escuela contrapuesta a la perspectiva individualizada del quehacer docente en el aula.Versión definitiv
KINEMATICS OF ETHIOPIAN RIFT AND MOTION OF AFRICA AND SOMALIA PLATES RELATIVE TO THE MANTLE
No full textFunctional complementation of sir2Δ yeast mutation by the human orthologous gene SIRT1
No full textSirtuins, class III histone deacetylases, are proteins homologous to the yeast protein Sir2p. Mammalian Sirt1 has
been shown to be involved in energy metabolism, brain functions, inflammation and aging through its deacetylase
activity, acting on both histone and non-histone substrates. In order to verify whether Sirt1 can replace Sir2p in the
yeast cells, we expressed the full-length human Sirt1 protein in S.cerevisiae sir2Δ mutant strain. The structure of
chromatin is basically maintained from yeast to human. Thus, yeast chromatin is a favourable environment to
evaluate, inhibit or activate an ectopic histone deacetylase activity in an in vivo substrate. Mutant sir2Δ shows a
series of different phenotypes, all dependent on the deacetylase activity of Sir2p. We analyzed the three silent loci
where normally Sir2p acts: ribosomal DNA, telomeres and the mating type loci. Moreover, we verified
extrachromosomal ribosomal DNA circles production and histone hyperacetylation levels, typical marks of sir2Δ
strains. By strong SIRT1 overexpression in sir2Δ cells, we found that specific molecular phenotypes of the mutant
revert almost to a wild-type condition. In particular, transcriptional silencing at rDNA was restored, extrachromosomal
rDNA circles formation was repressed and histone acetylation at H3K9 and H4K16 decreased. The complementation
at the other studied loci: HM loci, telomere and sub-telomere does not occur. Overall, our observations indicate that:
i) SIRT1 gene is able to complement different molecular phenotypes of the sir2Δ mutant at rDNA ii) the in vivo
screening of Sirt1 activity is possible in yeast.This work was partially supported by: the Istituto Pasteur-Fondazione Cenci Bolognetti, Università di Roma La Sapienza (http://
www.istitutopasteur.it/)and by the Epigenomics Flagship Project EpiGen, the Italian Ministry of Education and Research, National Research Council (http://
www.epigen.it/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
EXPLOITING VASOPRESSIN SIGNALLING IN MUSCULAR ATROPHY AND DYSTROPHIES
No full textThis study aims to evaluate the effects of the stimulation of the AVP-dependent pathways on muscular atrophy.
Arg-vasopressin (AVP) has been demonstrated to have a potent effect as myogenic promoting factor both in vitro and in vivo. In skeletal muscle AVP signaling is mediated by the V1a receptor, whose stimulation results in the activation of PLC and PLD, increased cytosolic calcium concentration and stimulation of CaMK (Ca2+/calmodulin-dependent protein kinase) and calcineurin pathways, leading to the formation of multifactor complexes on the promoter of muscle specific genes, thus activating their transcription.
In this study we induced muscular atrophy by local over-expression of TNF and we evaluated the effects of the stimulation of AVP signaling pathways in this condition by over-expressing V1a receptor. TNF is a pro-inflammatory cytokine and it is known to inhibit myogenic differentiation both in vitro and in vivo, and we have previously demonstrated that the negative effects of TNF in vitro is counteracted by AVP treatment. Moreover it has been demonstrated that TNF plays a key role in the activation of the inflammatory pathways mediated by NF-kB and in the stimulation of protein catabolism. For these reasons, we evaluated, in TNF-expressing muscle, the effects of V1aR over-expression in the regeneration process, in the inflammatory status and in protein degradation. Morphological and morphometric analysis demonstrated that the local over-expression of V1aR in the atrophic muscle enhances the cross-sectional area of the regenerating fibers. Since we noted the presence of infiltrating mono-nucleated cells in muscles over-expressing TNF, we investigated the nature of the infiltrate: it is positive for esterase activity, demonstrating the presence of macrophages. Esterase activity is reduced in muscles over-expressing both TNF and V1aR. We further demonstrated that the up-regulation of NF-kB expression by TNF is reduced by the contemporary over-expression of V1aR. We noted a prevalence of chemokines and cytokines specific of the pro-inflammatory phenotype of macrophages (M1) in the presence of TNF, but an increased levels of antigens and anti-inflammatory cytokines specific for M2 macrophage phenotype in muscle over-expressing both TNF and V1aR. In regards to the regenerative process, the expression levels of early regeneration markers, such as Pax7 and desmin, are up-regulated by TNF, whereas late differentiation markers, such as myogenin and MHC, are down-regulated. The simultaneous over-expression of V1aR up-regulates the expression of both early and late differentiation markers. These data demonstrate that the stimulation of AVP-dependent pathways enhances skeletal muscle regeneration. We also analyzed PI3K/Akt pathway because TNF is known to induce protein degradation. V1 over-expression maintains the phosphorylation levels of Akt and FoxO, at least inhibiting atrogin-1 transcription activated by TNF, thus counteracting protein degradation.
According to these results we are extending our studies to the effects of AVP signaling in muscular dystrophies. Very preliminary data suggest a positive role of AVP even in dystrophic muscles in mdx and Scgβ-null mice, though technical issues have yet to be solved
The COP9 signalosome is involved in the regulation of lipid metabolism and of transition metals uptake in Saccharomyces cerevisiae
No full text
Presenza di contaminanti ambientali in reperti archeologici: valutazione della concentrazione di metalli pesanti in reperti umani ed animali di provenienza pre e post industriale
No full textMetals present in the environment (soil, water and atmosphere) can affect food safety and human health through bioaccumulation and bio magnification phenomena. Human exposure to metals may take place through the environment and by ingesting contaminated food (including water), determining harmful effects usually over long time. Starting with the Industrial Revolution, local occurrence and concentration of metallic contaminants in the environment has been exponentially increasing: it has been assessed that present-day daily absorption of lead by North American individuals is noticeably greater than that during prehistoric times. In this study, antimony, arsenic, beryllium, cadmium, copper, lead, phosphorus, tin vanadium and zinc concentrations were measured in 153 bone samples (femurs) of Iron Age inhabitants of Central Italy (Abruzzo): the Samnites from the Alfedena Necropolis (2600–2400 B.P), 12 bones from the Sedilo Lochele Necropoli and 3 from the Grotta dei Colombi (Sardinia). As, Be, Cd, Cu, Pb, Sb, Sn, V, Zn determinations were carried out by quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS). P determination was carried out by UV-VIS Spectrophotometry. Found data are in agreement with results of similar published studies. Heavy metal concentrations varied widely among samples with the exception of zinc (round square deviation < 40%). A significant difference (p>90%) between the concentration of antimony, tin and cadmium male and female samples was found. Bioaccumulation phenomena has been confirmed. Data also confirm a mild relationship (r = 0.6 P=0,001) between lead and cadmium concentration. Burials of Alfedena were placed in defined areas outlined by stones placed and not directly interred whereas remains of individuals from the other necropolis (Sedilo-Lochele and Capo Figari) were found in collective burial caves. Diagenetic phenomena have been investigated by ICP-MS evaluation of metals concentration along the femur radial profile as well as by the evaluation of data obtained from laser-ablation mass spectrometry. Finally As, Be, Cd, Cu, Pb, Sb, Sn, V, Zn levels were measured in pleistocenic mammal bones. Results show concentrations in human buries are generally higher than animals nevertheless for a complete evaluation other investigations (taking in account the heterogeneity and number of samples) are necessary
Vulnerabilità Urbana e Mappe di Rischio per la Prevenzione Sismica e la Gestione dell'Emergenza
No full textThe quantitative measure of seismic vulnerability is a necessary requirement for prevention and for an optimal emergency management.
Before L'Aquila's earthquake in 2009, the National Civil Protection, in collaboration with the University of L'Aquila, developed a model to evaluate the criticality seismic of urban centers by using a multidisciplinary approach.
The study has led to the definition of a urban vulnerability index, that allows to identify the most critical urban centers and the problematic elements, in order to establish a hierarchy for preventative measures and for an efficient emergency management.
One of the features of this evaluation is that it allows a simultaneous analysis of the multiple factors involved in risk assessment.
After the seismic event occurred, same tests have been made to verify the validity of the model on the part of buildings, by comparing the criticality evaluated and damage suffered by the buildings, taking into account the local effects resulting from operations of microzonation. The seismic vulnerability index is calculated as the weighted sum of same parameters, that represent a building feature which can affect the structural response under earthquake ground motion. Therefore the influence of each parameter and their respective weights on the model have been analyzed. Sensitivity and Factorial analysis were performed to understand the model parameters that most affect structural vulnerability using the damage date collected after L'Aquila earthquake.
Furthermore a probabilistic correlation between the Vulnerability Index and the possible damage to the buildings resulting from an earthquake is provided. Moreover the vulnerability model is implemented in a probabilistic and quantitative risk analysis using the Event Tree Analysis Methodology.
As for the test performed, the methodology has a good level of confidence in the modelling of the vulnerability of the buildings so it can be successfully used for seismic risk assessment, necessary for seismic safety and emergency management.the thesis has been realized in collaboration with the National Civil Protectio