Browsing by Author "Ayala, M."

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Enhancement of Peroxidase Stability Against Oxidative Self-Inactivation by Co-immobilization with a Redox-Active Protein in Mesoporous Silicon and Silica Microparticles
    (2016) Sahare, P.; Osorio Román, Igor; Ayala, M.; Vazquez-Duhalt, R.; Pal, U.; Loni, A.; Canham, L. T.; Agarwal, V.
    Abstract The study of the stability enhancement of a peroxidase immobilized onto mesoporous silicon/silica microparticles is presented. Peroxidases tend to get inactivated in the presence of hydrogen peroxide, their essential co-substrate, following an auto-inactivation mechanism. In order to minimize this inactivation, a second protein was co-immobilized to act as an electron acceptor and thus increase the stability against self-oxidation of peroxidase. Two heme proteins were immobilized into the microparticles: a fungal commercial peroxidase and cytochrome c from equine heart. Two types of biocatalysts were prepared: one with only covalently immobilized peroxidase (one-protein system) and another based on covalent co-immobilization of peroxidase and cytochrome c (two-protein system), both immobilized by using carbodiimide chemistry. The amount of immobilized protein was estimated spectrophotometrically, and the characterization of the biocatalyst support matrix was performed using Brunauer–Emmett–Teller (BET), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), and Fourier transform infrared (FTIR) analyses. Stability studies show that co-immobilization with the two-protein system enhances the oxidative stability of peroxidase almost four times with respect to the one-protein system. Thermal stability analysis shows that the immobilization of peroxidase in derivatized porous silicon microparticles does not protect the protein from thermal denaturation, whereas biogenic silica microparticles confer significant thermal stabilization.Abstract The study of the stability enhancement of a peroxidase immobilized onto mesoporous silicon/silica microparticles is presented. Peroxidases tend to get inactivated in the presence of hydrogen peroxide, their essential co-substrate, following an auto-inactivation mechanism. In order to minimize this inactivation, a second protein was co-immobilized to act as an electron acceptor and thus increase the stability against self-oxidation of peroxidase. Two heme proteins were immobilized into the microparticles: a fungal commercial peroxidase and cytochrome c from equine heart. Two types of biocatalysts were prepared: one with only covalently immobilized peroxidase (one-protein system) and another based on covalent co-immobilization of peroxidase and cytochrome c (two-protein system), both immobilized by using carbodiimide chemistry. The amount of immobilized protein was estimated spectrophotometrically, and the characterization of the biocatalyst support matrix was performed using Brunauer–Emmett–Teller (BET), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), and Fourier transform infrared (FTIR) analyses. Stability studies show that co-immobilization with the two-protein system enhances the oxidative stability of peroxidase almost four times with respect to the one-protein system. Thermal stability analysis shows that the immobilization of peroxidase in derivatized porous silicon microparticles does not protect the protein from thermal denaturation, whereas biogenic silica microparticles confer significant thermal stabilization.
  • Thumbnail Image
    Item
  • Thumbnail Image
    Item
    Guías Latinoamericanas de Hipertensión Arterial
    (2010) Sánchez, R. A.; Ayala, M.; Baglivo, H.; Velázquez, C.; Burlando, G.; Kohlmann, O.; Jiménez, J.; López J, P.; Brandao, A.; Valdés Stromilli, Gloria; Alcocer, L.; Bendersky, M.; Ramírez, A. J.; Zanchetti, A.
    La hipertensión es un factor de riesgo cardiovascular muy prevalente en el mundo, y especialmente abrumador en los países de bajos y medianos ingresos. Informes recientes de la OMS y del Banco Mundial destacan la importancia de las enfermedades crónicas tales como la hipertensión, como obstáculo al logro de un buen estado de salud. Se debe agregar que, para la mayoría de los países de bajos y medianos ingresos, estrategias deficientes de la atención primaria de la salud son obstáculos mayores par el logro del control de la presión arterial. Es más, la epidemiología de la hipertensión y enfermedades relacionadas, los recursos y las prioridades de salud, el estado socioeconómico de la población, varían considerablemente en diferentes países y en diferentes regiones de países individuales. Teniendo en cuenta las bajas tasas de control de la presión arterial logrados en Latinoamérica y los beneficios que se puede esperar de un mejor control, se decidió invitar a especialistas de diferentes países latinoamericanos a analizar la situación de la región y redactar un documento de consenso sobre la detección, evaluación y tratamiento de la hipertensión que podría ser adecuado del punto de vista costo-utilidad. Las recomendaciones incluidas aquí son el resultado de documentos preparatorios escritos por expertos invitados y el muy activo debate posterior en diferentes paneles de discusión, realizados durante dos días en Asunción, Paraguay en Mayo del año 2008. Por último, para mejorar la práctica clínica, la publicación de estas pautas debe ser seguida por la implementación de intervenciones efectivas capaces de vencer las barreras (cognitivas, de comportamiento y afectivas) que previenen los cambios de actitud tanto en médicos como en pacientes.