The effect of alpha-ketoglutarate on a piscine skin model: a molecular and morphological study

Dissertação mest., Ciências Biomédicas, Universidade do Algarve, 2009Alpha-ketoglutarate (AKG) is a key intermediate in the tricarboxylic acid cycle with important functions in glutamate and glutamine metabolism. Its effect after oral administration was studied in adult sea bream Sparus aurata skin and scales in order to evaluate the effect on collagen synthesis. Scales were removed from one side of the body and allowed to regenerate for 14 days; the control group received untreated food, the AKG (calcium salt) group received 0.1g/kg in the diet (Gramineer International AB) and the placebo group received food treated with 140 mg calcium pills. AKG administration did not affect cortisol, estradiol, calcium or phosphorus levels in sea bream plasma, but the levels of aspartate-aminotransferase (AST) were higher in the AKG treated group when compared to the Control. AKG administration did not modify the overall organisation of the sea bream skin or of scale regeneration, as observed after tissue staining with Masson’s Trichrome. However, in the epidermis of the AKG treated group, the basement membrane was thicker than in the other groups both in the intact and regenerated scale, as revealed by birefringence under polarized light, which revealed a strong yellow band corresponding to collagen type I that was not observed in the control or placebo groups. Scale osteoblasts were identified by in situ hybridization with specific riboprobes and osteoclasts by TRAP staining and the content of ColIα1 and osteopontin in intact and regenerating skin was evaluated by qPCR. No differences in the expression of these two genes were observed between experimental groups, but an adequate reference gene still needs to be identified. Assessment of the elastic recoil of aortas from each experimental group revealed it was significantly higher in the AKG group compared to the control and this modification in rats was associated with an increase in collagen synthesis. This is in agreement with the increase in collagen detected in the skin by birefringence under polarized light in AKG treated fish although this observation will require confirmation by quantification of the collagen. In conclusion, the results of the present study provide evidence that AKG administration modifies collagen synthesis in sea bream. Further studies are required to confirm the effect of AKG on collagen synthesis and its mechanism of action during skin and scale regeneration

Hybrid threats in the context of european security: report of the international conference organized at the National Defence Institute (IDN) on 18 May 2021 under the framework of the Portuguese Presidency of the Council of the European Union

info:eu-repo/semantics/publishedVersio

Economic Growth and Carbon Dioxide Emissions in Italy, 1861-2003

This paper examines the relationship between economic growth and carbon dioxide emissions in Italy for the period 1861-2003. Using cointegration, rolling regression and error correction modeling techniques, we find that growth and carbon dioxide emissions are strongly interrelated, and elasticity of pollutant emissions with respect to income has been decreasing over time. For the period 1960-2003 EKC estimates provide evidence for the existence of a reasonable "turning point". However, given the heavy dependence of Italian economy upon fossil fuels, meeting the emissions targets in the accomplishing of the Kyoto Protocol is a very challenging task.Environmental Kuznets Curve; Carbon Dioxide Emissions; Time Series Analysis; Italian Economy

School retention rates in portuguese municipalities: a comparative analysis

Dissertation presented as a partial requirement for obtaining the Master’s degree in Statistics and Information Management with a specialization in Information Analysis and ManagementOne of the measures used to evaluate the success of an education system is the retention rate. In Portugal, in spite of the progress achieved in the past decades, students’ retention is still a problem. The phenomenon of school failure has been extensively studied throughout the world. Nevertheless, the way it is distributed across the country and the potential reasons that contribute to it being more intense in some areas than in others have not. The idea behind this project is to analyze the retention rates in middle school and in high school in the Portuguese public system, since the beginning of the decade and understand how they are distributed across the territory. The methods used were Principal Components Analysis and cluster analysis. The data related to potentially explanatory indicators of student failure – such as the average number of students per class, percentage of students in families who benefit from social support and the percentage of teachers with a permanent contract – were analyzed. The differences between the north and the south of the country are remarkable. Generally, the retention rates are much higher in the south than in the north. We also conclude that municipalities that are closer to each other have similar behaviors regarding their students’ success or unsuccess in terms of retention rates. Nevertheless, there are exceptions to the rule. For example, in Algarve, São Brás de Alportel stands out as a municipality that does particularly well in a context where retention rates are relatively high. Lastly, in this dissertation, we zoomed in the conurbations of Lisboa and Porto, where almost one in four children was enrolled in 2015/2016. The conclusions are striking: there are schools with some of the lowest retention rates while others, sometimes right across the street, can double the percentage of retained students