Hydrogen peroxide (H2O2) is generated in cells and plays an important role as a signalling molecule. It has been reported that H2O2 is involved in physiological and pathological processes in skeletal muscle. However, H2O2 detection in cells with traditional techniques produces frequent artefacts. Currently, the HyPer biosensor detects intracellular H2O2 specifically in real time using fluorescence microscopy. The aim of this study was to develop and optimize approaches used to express the HyPer biosensor in different models of skeletal muscle cells, such as the C2C12 myoblast/myotube cell line and mature skeletal muscle fibres isolated from C57BL/6J mice, and to measure intracellular H2O2 in real time in these cells. The results show that the expression of the HyPer biosensor in skeletal muscle cells is possible. In addition, we demonstrate that HyPer is functional and that this biosensor detects changes and fluctuations in intracellular H2O2 in a reversible manner. The HyPer2 biosensor, which is a more advanced version of HyPer, presents improved properties in terms of sensitivity in detecting lower concentrations of H2O2 in skeletal muscle fibres. In conclusion, the expression of the HyPer biosensor in the different experimental models combined with fluorescence microscopy techniques is a powerful methodology to monitor and register intracellular H2O2 specifically in skeletal muscle. The innovation of the methodological approaches presented in this study may present new avenues for studying the role of H2O2 in skeletal muscle pathophysiology. Furthermore, the methodology may potentially be adapted to yield other specific biosensors for different reactive oxygen and nitrogen species or metabolites involved in cellular functions.

El Grupo EPM experimenta un cambio notable en su estrategia de responsabilidad social. El objetivo de este trabajo es analizar la relación entre el cambio de estrategia y la postura política de la empresa en el área de influencia de la hidroeléctrica Río Grande II en Colombia. La responsabilidad social se asume teóricamente como una iniciativa de sostenibilidad corporativa. La metodología de investigación es un estudio de caso exploratorio. Los resultados muestran que la empresa busca una posición más central en su relación con el Estado y la comunidad local. El relacionamiento con el Estado se orienta hacia la construcción colectiva del territorio, y con la comunidad local se busca mayor participación. Esta nueva postura corporativa conlleva a procesos inexplorados donde se  compartan costos y beneficios con el Estado y la comunidad.

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This paper shows how Fuzzy Set Theory can be used in investment analysis when, as usual, these investments are developed under uncertainty, i.e. the investor has only subjective estimates based on his experience or knowledge about the future cash-flows of the investments, the discount rate, etc. In particular, we will develop basic concepts for investment analysis as the Net Present Value and the Internal Rate of Return by assuming that the initial data are fuzzy numbers. Later we will analyse how to rank investments and how to select the tangible investment portfolios when the magnitudes are estimated subjectively by comparing fuzzy numbers and with possibilistic mathematical programming.

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