Oxidative stress (OxS constitutes a disturbance caused by an imbalance between the generation of free radicals and antioxidant system, which causes damage to biomolecules. This, in turn, may lead the body to the occurrence of many chronic degenerative diseases. Therefore, it is very important to know the functioning of those endogenous (and exogenous antioxidants systems to prevent such diseases. Due to evolutionary conditions in living beings, among other functions have been developed and selected defense systems against the deleterious action of free radicals. Such systems are intrinsic in cells (at level intracellular and extracellular and act together with the dietary exogenous antioxidants. "ll these antioxidant systems have very important role in preserving the oxide/reduction equilibrium in the cell. To understand the role of the transcription factor Nrf in regulating the processes of antioxidant defense, it must also know the role of many of the endogenous antioxidants that occur because of its activation. Therefore, this chapter makes a literature review of the most important general aspects of endogenous antioxidant systems, which will provide another point of view from which to approach the study and treatment of many chronic degenerative diseases, such as diabetes, hypertension, and Parkinson. Keywords: oxidative stress, endogenous antioxidants, free radicals, catalase, glutathione . IntroductionThe aerobic organisms use mitochondria as the main generator of energy for the realization of its vital functions. To do this, these organelles produce "TP through reactions of oxidation and reduction and atach to the tricarboxylic acid cycle with the electron transport chain. This happen due to to the oxidation of the food and of the N"DH and F"DH , produced in diferent metabolic pathways, such as glycolysis, -oxidation, and the same Krebs cycle. However, these reactions invariably result in the generation of reactive oxygen species (ROS compounds that are unstable by having inal layer of electrons unpaired and that, in trying to stabilize itself sequester electrons from other biomolecules, making them also destabilizes and, therefore, is no longer able to perform their duties properly, thus altering the homeostasis and, ultimately, causing cell death. Due to the current oxidant characteristics of the atmosphere on our planet, organisms are afected by imbalances in the oxidation-reduction reactions, not only on many of their metabolic reactions but also on external factors, such as microbial infections, xenobiotics, toxins from the diet, radiation, environmental pollution, and so on. "ll this in conjunction can contribute to the generation or aggravation of many diseases, such as cancer, diabetes, Parkinson and so on [ ]. Other authors theorize that this imbalance in redox reactions has worked as an evolving pressure in order to develop efective mechanisms to eliminate the oxygen toxicity; this allowed the evolution of higher forms of living organisms, which are much more specialized and protected a...

El presente trabajo tuvo como objetivo principal determinar los posibles impactos sobre el suelo agrícola del Valle deMetztitlán, que se tendrán con la construcción de una segunda refinería en Tula Hidalgo; de acuerdo a un estudio realizado por García et al., en 2005 [1], existe la presencia de HAPs en agua y sedimento del Río y la Laguna del Valle deMetztitlán, lo cual podría estar causando un efecto negativo sobre la población, tanto en la salud como en las cosechas.Para este estudio se utilizó suelo con azolve contaminado con HAPs proveniente de una refinería. En la primera etapa, sehizo una revisión bibliográfica acerca de las enfermedades ocasionadas por estos contaminantes que ha reportado lasecretaria de salud del estado de Hidalgo (SSAH) en 2009 [2]. En la segunda etapa, se realizó una caracterizaciónfisicoquímica determinando parámetros (pH, capacidad de campo, porcentaje de humedad, materia orgánica y compuestos inorgánicos) que pudieran influir en la degradación de este contaminante mediante métodos establecidos por Cárdenas en 2003 [3] y por normas ambientales mexicanas. En la tercera etapa, se determinó el HAP más persistente y el más tóxico mediante el método para barrido de compuestos orgánicos establecido en la NOM- 138-SEMARNAT-2003 [4].Finalmente, se establecieron microcosmos en condiciones anaerobias. De estos microcosmos se tomaron 30 g de suelodonde posteriormente se aclimataron consorcios microbianos para evaluar el posible tiempo de degradación delhidrocarburo encontrado: criseno. Para estas pruebas de biodegradación se utilizó un HAP surrogado que tuviera casi lasmismas propiedades fisicoquímicas que el identificado, en este caso fue el 3- y 6- hidroxicriseno, como resultado seobtuvo que este surrogado se degrada en un sistema, de membrana limitante de oxígeno (MLO) en un lapso de tiempo de40 días.

Hoy en día es una necesidad urgente con carácter social, de salud humana, ambiental e incluso política, asegurar el abastecimiento de agua a las ciudades y poblados de nuestro país. En el caso del Distrito Federal, esta ciudad cuenta con una geografía característica que permite cada año un aporte de agua de lluvia de casi 780 millones de m3 pero solo cerca del 13% de este volumen, se aprovecha. La naturaleza da ejemplos de cómo pueden ser diseñados los sistemas para capturar agua pluvial. Al proceso de estudiar las soluciones que la propia naturaleza ha adoptado se le conoce como biomimetismo y la biomimética es la tecnología que imita a la naturaleza. El objetivo de este trabajo fue copiar principios simples de la naturaleza para diseñar un sistema biomimético de captura y filtración de agua pluvial para casas particulares y unidades habitacionales. Para el diseño del captador biomimético se trabajó con materiales ligeros que no absorben agua sino que la conducen con rapidez a depósitos, debido a que se favorece el fenómeno de cohesión. De los estudios se obtuvo la impermeabilidad de los materiales, su resistencia al flujo y se calcularon los coeficientes de cohesión alcanzados, lo que indica que tanto la moléculas de agua se agrupan entre si y así se evita que se humedezcan los materiales captadores. Estos datos permitieron el diseño final de un primer prototipo.

Several batch scale assays were performed in order to establish a correlation between the microbial removals of neicosane, in presence of different concentrations of volatile organic compounds (VOCs) which showed a partial removing.The selected VOCs were toluene and benzene. Results with benzene showed that the removal of this aromatic compoundwas decreased in presence of n-eicosane and the lowest removal was obtained when VOC concentration was higher. Theremoval of hydrocarbon was increased when VOC concentration was increased. In the assays with toluene, n-eicosanereached a higher removal when VOC concentration was increased, but the aromatic compound showed a decrease in itselimination dynamics. Control assays performed with VOCs at 28 mg/L without hydrocarbon showed higher removaldynamics for benzene than toluene. Also control assays of n-eicosane at two different concentrations but without anyVOC showed that its removal dynamic decreased in the absence of the aromatic compounds for both assays. The kineticadjustrnent obtained for toluene (Hill kinetic model) showed that the removal rate of this compound increased while itsconcentration at water-phase was higher. Although, when it was used a concentration of 50 mg/L or higher, the removalrate became almost constant. For benzene, the higher removal rate was reached with 38 mg/L. With higher concentration,the kinetic model showed inhibition, so the adjustrnent analyses fitted for a Monod kinetic model. n-Eicosane showed abetter adjustrnent with the Haldane kinetic model with an initial concentration of 188 mg/L for the highest removal rate.

This chapter deals with the history of the humanitarian use of animals in laboratory experiments from ancient times to the present day. It emphasizes the various criteria that have been established to try to improve the quality of life of an animal and its sacrifice with euthanasic techniques, since the emergence of Russell's statement of the three Rs (replacement, reduction, and refinancing). In addition, there is a review of the application of bioethical principles in scientific institutions in developing countries, such as Mexico. It also reviews some aspects of the humanitarian treatment of experimental animals at the time of designing an experiment protocol.