Luis Briones - Academia.edu (original) (raw)
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Papers by Luis Briones
The UV/Vis spectral behavior of three solvatochromic N-alkyl a-pyridones of varying lipophilicity... more The UV/Vis spectral behavior of three solvatochromic N-alkyl a-pyridones of varying lipophilicity was investigated in aqueous solutions of a block copolymer at variable temperatures. The solvatochromic responses of the three analogues to the distinct microenvironments were compared and interpreted in terms of their different location in the microheterogeneous system. The interpretation was supported by 1 H NMR measurements and by molecular dynamics simulations that mimicked the interactions of the dyes with the polymeric micelle in water.
Journal of Colloid and Interface Science, 2010
A spectral investigation of the thermochromic behavior of Reichardt's E T (30) betaine in aqueous... more A spectral investigation of the thermochromic behavior of Reichardt's E T (30) betaine in aqueous solutions of block copolymers (''poloxamers") P407, P237 and P105 was carried out as a function of temperature and concentration. The betaine microenvironment at various stages of the micellization process in these systems was mimicked with the aid of molecular dynamics simulations of model systems. These consisted of the E T (30) probe in boxes of water molecules, in the presence of an isolated block copolymer of formula (PEO) 11 -(PPO) 16 -(PEO) 11 , and of a micelle formed of 50 of these unimers.
FEMS Yeast Research, 2013
Ethanol accumulation during fermentation contributes to the toxic effects in Saccharomyces cerevi... more Ethanol accumulation during fermentation contributes to the toxic effects in Saccharomyces cerevisiae, impairing its viability and fermentative capabilities. The iron-sulfur (Fe-S) cluster biogenesis is encoded by the ISC genes. Reactive oxygen species (ROS) generation is associated with iron release from Fe-S-containing enzymes. We evaluated ethanol toxicity, ROS generation, antioxidant response and mitochondrial integrity in S. cerevisiae ISC mutants. These mutants showed an impaired tolerance to ethanol. ROS generation increased substantially when ethanol accumulated at toxic concentrations under the fermentation process. At the cellular and mitochondrial levels, ROS were increased in yeast treated with ethanol and increased to a higher level in the ssq1Δ, isa1Δ, iba57Δ and grx5Δ mutants -hydrogen peroxide and superoxide were the main molecules detected. Additionally, ethanol treatment decreased GSH/GSSG ratio and increased catalase activity in the ISC mutants. Examination of cytochrome c integrity indicated that mitochondrial apoptosis was triggered following ethanol treatment. The findings indicate that the mechanism of ethanol toxicity occurs via ROS generation dependent on ISC assembly system functionality. In addition, mutations in the ISC genes in S. cerevisiae contribute to the increase in ROS concentration at the mitochondrial and cellular level, leading to depletion of the antioxidant responses and finally to mitochondrial apoptosis.
PRESENTACIÓN La Universidad Técnica de Manabí, consciente de su papel protagónico con las nuevas ... more PRESENTACIÓN La Universidad Técnica de Manabí, consciente de su papel protagónico con las nuevas generaciones, asumió el reto de realizar el SEMESTRE BÁSICO UNIVERSITARIO (SBU), el mismo que contempla entre otros, el evento de INVESTIGACIÓN FORMATIVA, área social que debe constituirse en una disciplina, en una pedagogía concientizadora y creativa y, en esa medida, en una herramienta al servicio del crecimiento del docente y los alumnos comprometidos con la producción y la transformación social.
The UV/Vis spectral behavior of three solvatochromic N-alkyl a-pyridones of varying lipophilicity... more The UV/Vis spectral behavior of three solvatochromic N-alkyl a-pyridones of varying lipophilicity was investigated in aqueous solutions of a block copolymer at variable temperatures. The solvatochromic responses of the three analogues to the distinct microenvironments were compared and interpreted in terms of their different location in the microheterogeneous system. The interpretation was supported by 1 H NMR measurements and by molecular dynamics simulations that mimicked the interactions of the dyes with the polymeric micelle in water.
Journal of Colloid and Interface Science, 2010
A spectral investigation of the thermochromic behavior of Reichardt's E T (30) betaine in aqueous... more A spectral investigation of the thermochromic behavior of Reichardt's E T (30) betaine in aqueous solutions of block copolymers (''poloxamers") P407, P237 and P105 was carried out as a function of temperature and concentration. The betaine microenvironment at various stages of the micellization process in these systems was mimicked with the aid of molecular dynamics simulations of model systems. These consisted of the E T (30) probe in boxes of water molecules, in the presence of an isolated block copolymer of formula (PEO) 11 -(PPO) 16 -(PEO) 11 , and of a micelle formed of 50 of these unimers.
FEMS Yeast Research, 2013
Ethanol accumulation during fermentation contributes to the toxic effects in Saccharomyces cerevi... more Ethanol accumulation during fermentation contributes to the toxic effects in Saccharomyces cerevisiae, impairing its viability and fermentative capabilities. The iron-sulfur (Fe-S) cluster biogenesis is encoded by the ISC genes. Reactive oxygen species (ROS) generation is associated with iron release from Fe-S-containing enzymes. We evaluated ethanol toxicity, ROS generation, antioxidant response and mitochondrial integrity in S. cerevisiae ISC mutants. These mutants showed an impaired tolerance to ethanol. ROS generation increased substantially when ethanol accumulated at toxic concentrations under the fermentation process. At the cellular and mitochondrial levels, ROS were increased in yeast treated with ethanol and increased to a higher level in the ssq1Δ, isa1Δ, iba57Δ and grx5Δ mutants -hydrogen peroxide and superoxide were the main molecules detected. Additionally, ethanol treatment decreased GSH/GSSG ratio and increased catalase activity in the ISC mutants. Examination of cytochrome c integrity indicated that mitochondrial apoptosis was triggered following ethanol treatment. The findings indicate that the mechanism of ethanol toxicity occurs via ROS generation dependent on ISC assembly system functionality. In addition, mutations in the ISC genes in S. cerevisiae contribute to the increase in ROS concentration at the mitochondrial and cellular level, leading to depletion of the antioxidant responses and finally to mitochondrial apoptosis.
PRESENTACIÓN La Universidad Técnica de Manabí, consciente de su papel protagónico con las nuevas ... more PRESENTACIÓN La Universidad Técnica de Manabí, consciente de su papel protagónico con las nuevas generaciones, asumió el reto de realizar el SEMESTRE BÁSICO UNIVERSITARIO (SBU), el mismo que contempla entre otros, el evento de INVESTIGACIÓN FORMATIVA, área social que debe constituirse en una disciplina, en una pedagogía concientizadora y creativa y, en esa medida, en una herramienta al servicio del crecimiento del docente y los alumnos comprometidos con la producción y la transformación social.