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Search Results: 1 - 10 of 198586 matches for " Juan E. Arenas "
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Sex Steroids and Breast Cancer: An Overview  [PDF]
Zeina Nahleh, Juan E. Arenas, Arafat Tfayli
Journal of Cancer Therapy (JCT) , 2013, DOI: 10.4236/jct.2013.44097
Abstract:

Sex steroids, also known as sex hormones are synthesized naturally by the gonads (ovaries or testes). The two main classes of sex steroids, androgens and estrogens, are crucial hormones for the proper development and function of the body; they regulate sexual differentiation, the secondary sex characteristics, and sexual habits. They are also well known to influence many common cancers, especially hormonally driven cancers such as breast and prostate cancer. In this report, we review the association of sex steroids with cancer and the potential use of endocrine manipulation in cancer therapy as well as the limitations and challenges faced in this field.

Qué es un pterigión reproducido en la era actual? What is a reproduced pterygium these days?
E. Arenas
Archivos de la Sociedad Espa?ola de Oftalmología , 2012,
Abstract:
La estructura (4a) del desdoblamiento de calzada entre Lasarte y Andoaín
Arenas de Pablo, Juan José
Informes de la Construccion , 1978,
Abstract: This article describes the concept, design and analysis of a continuous concrete, capped type, overpass, prestressed with a 56° skewing angle. This article includes considerations regarding the savings in prestressed steel as a result of the skewing as compared to that which would have been produced by using a reinforced concrete slab, and on the structural prestress effects contemplated as a voluntary compensating action of external loads as well on the size of the passive reinforcement required for cutting and torsion stresses. It discusses the resistant mechanisms developed in a panel of this type and it points out relatively simple analysis procedures of same, subjected to lads which are normal on its plane and of obtention of horizontal action on piles caused by the forces and deformations imposed in same. Finally, construction aspects such as the solution adopted to eliminate bench walls, which can be of a practical interest, are detailed. Se describen en este artículo la concepción, el dise o y el análisis de un paso superior del tipo dintel continuo de hormigón pretensado con un ángulo de esviaje de 56°. El artículo incluye consideraciones sobre el ahorro de acero de pretensado a causa del esviaje respecto al que se produciría en una losa de hormigón armado, sobre los efectos estructurales del pretensado contemplado como acción voluntaria compensadora de las cargas exteriores, y sobre el dimensionamiento de la armadura pasiva precisa por los esfuerzos de corte y torsión. Plantea los mecanismos resistentes que se desarrollan en un tablero de este tipo y expone procedimientos, relativamente simples, de análisis del mismo sometido a cargas normales a su plano y de obtención de acciones horizontales sobre pilas a causa de las fuerzas y de las deformaciones impuestas en aquél. Se detallan, por último, aspectos constructivos, tales como la solución adoptada para eliminar los muros estribos, que pueden ofrecer interés práctico.
Presentación
Juan Carlos Arenas Gómez
Estudios Políticos , 2011,
Abstract:
Catalases Are NAD(P)H-Dependent Tellurite Reductases
Iván L. Calderón, Felipe A. Arenas, José Manuel Pérez, Derie E. Fuentes, Manuel A. Araya, Claudia P. Saavedra, Juan C. Tantaleán, Sergio E. Pichuantes, Philip A. Youderian, Claudio C. Vásquez
PLOS ONE , 2006, DOI: 10.1371/journal.pone.0000070
Abstract: Reactive oxygen species damage intracellular targets and are implicated in cancer, genetic disease, mutagenesis, and aging. Catalases are among the key enzymatic defenses against one of the most physiologically abundant reactive oxygen species, hydrogen peroxide. The well-studied, heme-dependent catalases accelerate the rate of the dismutation of peroxide to molecular oxygen and water with near kinetic perfection. Many catalases also bind the cofactors NADPH and NADH tenaciously, but, surprisingly, NAD(P)H is not required for their dismutase activity. Although NAD(P)H protects bovine catalase against oxidative damage by its peroxide substrate, the catalytic role of the nicotinamide cofactor in the function of this enzyme has remained a biochemical mystery to date. Anions formed by heavy metal oxides are among the most highly reactive, natural oxidizing agents. Here, we show that a natural isolate of Staphylococcus epidermidis resistant to tellurite detoxifies this anion thanks to a novel activity of its catalase, and that a subset of both bacterial and mammalian catalases carry out the NAD(P)H-dependent reduction of soluble tellurite ion (TeO3 2?) to the less toxic, insoluble metal, tellurium (Te°), in vitro. An Escherichia coli mutant defective in the KatG catalase/peroxidase is sensitive to tellurite, and expression of the S. epidermidis catalase gene in a heterologous E. coli host confers increased resistance to tellurite as well as to hydrogen peroxide in vivo, arguing that S. epidermidis catalase provides a physiological line of defense against both of these strong oxidizing agents. Kinetic studies reveal that bovine catalase reduces tellurite with a low Michaelis-Menten constant, a result suggesting that tellurite is among the natural substrates of this enzyme. The reduction of tellurite by bovine catalase occurs at the expense of producing the highly reactive superoxide radical.
Bacterial Toxicity of Potassium Tellurite: Unveiling an Ancient Enigma
José M. Pérez, Iván L. Calderón, Felipe A. Arenas, Derie E. Fuentes, Gonzalo A. Pradenas, Eugenia L. Fuentes, Juan M. Sandoval, Miguel E. Castro, Alex O. Elías, Claudio C. Vásquez
PLOS ONE , 2007, DOI: 10.1371/journal.pone.0000211
Abstract: Biochemical, genetic, enzymatic and molecular approaches were used to demonstrate, for the first time, that tellurite (TeO3 2?) toxicity in E. coli involves superoxide formation. This radical is derived, at least in part, from enzymatic TeO3 2? reduction. This conclusion is supported by the following observations made in K2TeO3-treated E. coli BW25113: i) induction of the ibpA gene encoding for the small heat shock protein IbpA, which has been associated with resistance to superoxide, ii) increase of cytoplasmic reactive oxygen species (ROS) as determined with ROS-specific probe 2′7′-dichlorodihydrofluorescein diacetate (H2DCFDA), iii) increase of carbonyl content in cellular proteins, iv) increase in the generation of thiobarbituric acid-reactive substances (TBARs), v) inactivation of oxidative stress-sensitive [Fe-S] enzymes such as aconitase, vi) increase of superoxide dismutase (SOD) activity, vii) increase of sodA, sodB and soxS mRNA transcription, and viii) generation of superoxide radical during in vitro enzymatic reduction of potassium tellurite.
Tubal pregnancy with molar degeneration in concurrent eutopic pregnancy. A case report  [PDF]
Jesus Joaquin Hijona Elosegui, Antonio Carballo Garcia, Francisco Javier Frutos Arenas, Juan Manuel Torres Marti
Open Journal of Obstetrics and Gynecology (OJOG) , 2011, DOI: 10.4236/ojog.2011.12011
Abstract: This research paper presents the infrequent case of a heterotopic pregnancy based on a tubal ectopic pregnancy with molar degeneration in concurrent eutopic pregnancy. Treatment with evacuation/suction curettage and perlaparoscopic salpingectomy was required. This case report confirms what is biologically valid in the statistically unlikely.
Discriminación de Sexo en una Población Medieval del Sur de la Península Ibérica Mediante el Uso de Variables Simples
Jiménez-Arenas,Juan Manuel;
International Journal of Morphology , 2010, DOI: 10.4067/S0717-95022010000300003
Abstract: sex determination on osteological remains is key since it is the initial step to establish another kind of biological and cultural inferences. though sex determination arises easily when some particular parts of the skeleton are collected, specifically the pelvis and the skull, this target is more difficult from other bones, specifically when they are fragmented. in the present paper a study on sex discrimination based on simple humeral variables is shown. the use of the lubischew?s test show that at least one variable in each part of the humerus provides a discriminant percentage close to 90%. these results are compared with those obtained by discriminanting analysis. from an archaeological point of view, the lubischew?s test is a useful tool to infer the sex of the uncertain individuals belonging to large enough samples with previous reliable sex assigments.
Fondos de pensiones y su impacto en los mercados locales en 2007
Camilo José Arenas,Juan Camilo Dauder
Perfil de Coyuntura Económica , 2006,
Abstract: en el documento se realiza el análisis del comportamiento reciente de los recursos administrados y la composición de los portafolios de las Administradoras de Fondos de Pensiones (AFP) en comparación con otros países de América Latina. Posteriormente, se hace la proyección del crecimiento de los portafolios para 2007, con el fin de determinar los flujos mensuales que destinarán estos inversionistas a los activos de renta fija, renta variable e inversiones en el exterior.
Discriminación de Sexo en una Población Medieval del Sur de la Península Ibérica Mediante el Uso de Variables Simples Sex Discrimination in a Middle Age Population of the Southern Iberian Peninsula by the Use of Simple Variables
Juan Manuel Jiménez-Arenas
International Journal of Morphology , 2010,
Abstract: Las asignaciones de sexo a los restos osteológicos es fundamental puesto que suponen el primer paso hacia el establecimiento de otros tipos de inferencias biológicas y culturales. Aunque la determinación del sexo es relativamente fácil cuando se recuperan determinadas partes esqueléticas, especialmente la pelvis y el cráneo, resulta más problemática a partir de otros huesos, sobre todo si se trata de fragmentos. En este trabajo se presenta un estudio de discriminación del sexo de los individuos a partir del húmero utilizando variables simples. Los resultados muestran cómo, utilizando la prueba de Lubischew, cada una de las principales partes del húmero aporta, al menos, una variable con porcentajes de discriminación cercanos al 90%. Estos resultados se comparan con los obtenidos mediante análisis discriminantes. Desde el punto de vista de la aplicación en Arqueología, la prueba de Lubischew se presenta como una herramienta muy útil para la asignación de sexo a individuos de sexo desconocido pertenecientes a muestras suficientemente amplias, siempre y cuando existan asignaciones sexuales previas fiables para un porcentaje alto de los individuos de cada una de aquéllas. Sex determination on osteological remains is key since it is the initial step to establish another kind of biological and cultural inferences. Though sex determination arises easily when some particular parts of the skeleton are collected, specifically the pelvis and the skull, this target is more difficult from other bones, specifically when they are fragmented. In the present paper a study on sex discrimination based on simple humeral variables is shown. The use of the Lubischew’s test show that at least one variable in each part of the humerus provides a discriminant percentage close to 90%. These results are compared with those obtained by discriminanting analysis. From an archaeological point of view, the Lubischew’s test is a useful tool to infer the sex of the uncertain individuals belonging to large enough samples with previous reliable sex assigments.
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