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Search Results: 1 - 10 of 554448 matches for " Diego F Mejía-Espa?a "
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Inactivación Térmica de Pectinmetilesterasa en Tomate de árbol (Solanum betaceum) Thermal Inactivation of Pectinmethylesterase in Tree Tomato (Solanum betaceum)
Maira P Maca,Oswaldo Osorio,Diego F Mejía-Espaa
Información Tecnológica , 2013,
Abstract: El objetivo de esta investigación fue estudiar el efecto del procesamiento térmico a temperatura constante, sobre la actividad residual de la enzima pectinmetilesterasa (PME), causante de la separación de fases en néctar de tomate de árbol (Solanum betaceum). Se evaluó un rango de temperaturas entre 40 y 90°C y tiempos de exposición entre los 5 y 20s. La actividad enzimática residual se midió por espectrofotometría a una longitud de onda de 620 nm. Se determinó el contenido de proteína mediante el método de Bradford. El tratamiento térmico aplicado a 60oC durante 20 segundos de exposición redujo la actividad residual de PME hasta un 10% evitando la separación de fases del néctar. Se concluye que el tratamiento aplicado disminuyó el contenido de enzima en un 28% con respecto al testigo sin tratar. The effect of batch thermal processing on the residual activity of pectinmethylesterase enzyme (PME) in tree tomato (Solanum betaceum) was studied. Batch processes were conducted at temperatures between 40 and 90°C and exposure times from 5 to 20s. Residual enzyme activity was spectrophotometrically measured at 620 nm wavelength. The protein content was determined according to Bradford′s dye binding method. The thermal treatment applied to 60°C for 20 seconds exposure time, reduced the residual activity of PME to 10% avoiding phase separation. It is concluded that the thermal treatment applied caused a decrease on enzyme content to 28% from initial content.
In Vitro Activity of Squaramides and Acyclic Polyamine Derivatives against Trophozoites and Cysts of Acanthamoeba castellanii  [PDF]
M. J. Rosales, M. Ximenis, A. Costa, C. Rotger, D. Romero, F. Olmo, E. Delgado, M. P. Clares, E. García-Espaa, C. Marín, M. Sánchez
Journal of Biosciences and Medicines (JBM) , 2018, DOI: 10.4236/jbm.2018.68001
Abstract: Pathogenic strains of Acanthamoeba cause keratitis (AK), granulomatous amoebic encephalitis (GAE), amoebic pneumonitis (AP), and skin infection in human and animals. The treatment of an Acanthamoeba infection is invariably very difficult and not always effective, and compounds that are amebicidic or amebistatic are frequently toxic and/or irritating for humans. Squaramides and polyamine derivatives have been demonstrated to have antitumor and antiprotozoal activity. The aim of this study was to investigate the activity of 5 squaramides and 5 acyclic polyamines against trophozoites and cysts of A. castellanii Neff. Amoebicidal activity against the trophozoites and cytotoxicity against Vero cells were evaluated with a colorimetric assay, using Alamar Blue?, and chlorhexidine digluconate was assayed as the reference drug. The squaramides 3 and 5 and the acyclic polyamine 6 appeared to be the most active against the trophozoites and their cytotoxicity was low, showing selectivity indexes of 28.3, 26, and 25.7, respectively, similar to the control drug, chlorhexidine digluconate (27.6). But only the squaramide 3 showed complete cysticidal activity at the concentrations of 100 and 200 μM, as the chlorhexidine digluconate. Further studies of the mechanism of action and in vivo assays are needed, but squaramide 3 could be used for developing novel therapeutic approaches against Acanthamoeba infections.
DOR/Tp53inp2 and Tp53inp1 Constitute a Metazoan Gene Family Encoding Dual Regulators of Autophagy and Transcription
Ana Sancho, Jordi Duran, Antonio García-Espaa, Caroline Mauvezin, Endalkachew A. Alemu, Trond Lamark, Maria J. Macias, Rob DeSalle, Miriam Royo, David Sala, Javier U. Chicote, Manuel Palacín, Terje Johansen, Antonio Zorzano
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0034034
Abstract: Human DOR/TP53INP2 displays a unique bifunctional role as a modulator of autophagy and gene transcription. However, the domains or regions of DOR that participate in those functions have not been identified. Here we have performed structure/function analyses of DOR guided by identification of conserved regions in the DOR gene family by phylogenetic reconstructions. We show that DOR is present in metazoan species. Invertebrates harbor only one gene, DOR/Tp53inp2, and in the common ancestor of vertebrates Tp53inp1 may have arisen by gene duplication. In keeping with these data, we show that human TP53INP1 regulates autophagy and that different DOR/TP53INP2 and TP53INP1 proteins display transcriptional activity. The use of molecular evolutionary information has been instrumental to determine the regions that participate in DOR functions. DOR and TP53INP1 proteins share two highly conserved regions (region 1, aa residues 28–42; region 2, 66–112 in human DOR). Mutation of conserved hydrophobic residues in region 1 of DOR (that are part of a nuclear export signal, NES) reduces transcriptional activity, and blocks nuclear exit and autophagic activity under autophagy-activated conditions. We also identify a functional and conserved LC3-interacting motif (LIR) in region 1 of DOR and TP53INP1 proteins. Mutation of conserved acidic residues in region 2 of DOR reduces transcriptional activity, impairs nuclear exit in response to autophagy activation, and disrupts autophagy. Taken together, our data reveal DOR and TP53INP1 as dual regulators of transcription and autophagy, and identify two conserved regions in the DOR family that concentrate multiple functions crucial for autophagy and transcription.
Analysis of the Ush2a Gene in Medaka Fish (Oryzias latipes)
Elena Aller, Ana V. Sánchez-Sánchez, Javier U. Chicote, Gema García-García, Patricia Udaondo, Laura Cavallé, Marina Piquer-Gil, Antonio García-Espaa, Manuel Díaz-Llopis, José M. Millán, José L. Mullor
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0074995
Abstract: Patients suffering from Usher syndrome (USH) exhibit sensorineural hearing loss, retinitis pigmentosa (RP) and, in some cases, vestibular dysfunction. USH is the most common genetic disorder affecting hearing and vision and is included in a group of hereditary pathologies associated with defects in ciliary function known as ciliopathies. This syndrome is clinically classified into three types: USH1, USH2 and USH3. USH2 accounts for well over one-half of all Usher cases and mutations in the USH2A gene are responsible for the majority of USH2 cases, but also for atypical Usher syndrome and recessive non-syndromic RP. Because medaka fish (Oryzias latypes) is an attractive model organism for genetic-based studies in biomedical research, we investigated the expression and function of the USH2A ortholog in this teleost species. Ol-Ush2a encodes a protein of 5.445 aa codons, containing the same motif arrangement as the human USH2A. Ol-Ush2a is expressed during early stages of medaka fish development and persists into adulthood. Temporal Ol-Ush2a expression analysis using whole mount in situ hybridization (WMISH) on embryos at different embryonic stages showed restricted expression to otoliths and retina, suggesting that Ol-Ush2a might play a conserved role in the development and/or maintenance of retinal photoreceptors and cochlear hair cells. Knockdown of Ol-Ush2a in medaka fish caused embryonic developmental defects (small eyes and heads, otolith malformations and shortened bodies with curved tails) resulting in late embryo lethality. These embryonic defects, observed in our study and in other ciliary disorders, are associated with defective cell movement specifically implicated in left-right (LR) axis determination and planar cell polarity (PCP).
Metodología alternativa para el tratamiento de problemas de programación entera usando programación no lineal
Diego A. Mejía Giraldo,Alexander Molina C.,Francisco F. Franco A.
Scientia Et Technica , 2007,
Abstract: Este trabajo propone una alternativa de solución a los problemas de Programación Entera, dejando de lado la idea de la enumeración implícita y sus consecuentes dificultades a la vez que aprovecha información matemática de la función objetivo y de las funciones que determinan el espacio de soluciones. Tal alternativa de solución es posible gracias a una sencilla transformación de las restricciones de integralidad usando un polinomio que permite tratar el problema con Programación No Lineal (PNL).
SOLUCIóN AL PROBLEMA DEL DESPACHO DE ENERGíA EN SISTEMAS HIDROTéRMICOS USANDO SIMULATED ANNEALING
DIEGO A. MEJíA GIRALDO,FRANCISCO F. FRANCO A.,RAMóN ALFONSO GALLEGO
Scientia Et Technica , 2005,
Abstract: Este artículo describe el problema de Despacho Hidrotérmico (DHT) en Sistemas Eléctricos de Potencia. El modelo matemático que lo describe, es linealizado y para su solución se emplea Programación Lineal (PL) apoyada de una metodología de optimización combinatorial denominada Simulated Annealing (SA). Un sistema eléctrico compuesto por tres unidades hidráulicas y dos plantas térmicas es usado para llevar a cabo la implementación de la metodología propuesta. Los resultados obtenidos con SA son comparados con los obtenidos por Branch and Bound (B&B), una técnica clásica y eficiente de la Programación Entera Mixta (PEM). El algoritmo de SA encuentra respuestas de excelente calidad, mostrando el gran potencial del método de solución a este tipo de problemas.
Técnicas de control adaptativas aplicadas a sistemas multivariables (M.I.M.O.)
Diego A. Mejía Giraldo,Ricardo Andrés Bola?os O.,Carlos Adrián Correa F.
Scientia Et Technica , 2007,
Abstract: En este artículo muestra un control PID y por Reubicación de Polos que son implementados adaptativamente, mediante la incorporación de variantes para que el sistema pueda ser manejado desde un computador digital por medio de la adquisición de datos. Se simula el control multivariable de frecuencia y voltaje de un generador sincrónico real de 1/3 Hp, 120 V, 1800 RPM y 4 polos. Sus parámetros fueron identificados previamente de manera adaptativa partiendo de un modelo matemático de tercer orden (esquema de identificación fuera de línea). Los resultados obtenidos muestran la eficacia de ambas estructuras de control.
Matrix iterations and Cichon's diagram
Diego Alejandro Mejía
Mathematics , 2012, DOI: 10.1007/s00153-012-0315-6
Abstract: Using matrix iterations of ccc posets, we prove the consistency with ZFC of some cases where the cardinals on the right hand side of Cichon's diagram take two or three arbitrary values (two regular values, the third one with uncountable cofinality). Also, mixing this with the techniques in J Symb Log 56(3):795-810, 1991, we can prove that it is consistent with ZFC to assign, at the same time, several arbitrary regular values on the left hand side of Cichon's diagram.
Preservation properties for iterations with finite support
Diego Alejandro Mejía
Mathematics , 2015,
Abstract: We present the classical theory of preservation of $\sqsubset$-unbounded families in generic extensions by ccc posets, where $\sqsubset$ is a definable relation of certain type on spaces of real numbers, typically associated with some classical cardinal invariant. We also prove that, under some conditions, these preservation properties can be preserved in direct limits of an iteration, so applications are extended beyond the context of finite support iterations. Also, we make a breve exposition of Shelah's theory of forcing with an ultrapower of a poset by a measurable cardinal.
Models of some cardinal invariants with large continuum
Diego Alejandro Mejía
Mathematics , 2013,
Abstract: We extend the applications of the techniques used in Arch Math Logic 52:261-278, 2013, to present various examples of consistency results where some cardinal invariants of the continuum take arbitrary regular values with the size of the continuum being bigger than $\aleph_2$.
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