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Search Results: 1 - 10 of 379501 matches for " Pérez de la Cruz "
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Historia de la alimentación parenteral: primera lección Jesús Culebras History of parenteral nutrition: first Jesus Culebras lecture
A. J. Pérez de la Cruz
Nutrición Hospitalaria , 2010,
Abstract:
Escherichia coli genes affecting recipient ability in plasmid conjugation: Are there any?
Daniel Pérez-Mendoza, Fernando de la Cruz
BMC Genomics , 2009, DOI: 10.1186/1471-2164-10-71
Abstract: Results indicate that no non-essential recipient E. coli genes exist that play an essential role in conjugation. Mutations in the lipopolysaccharide (LPS) synthesis pathway had a modest effect on R388 plasmid transfer (6 – 32% of wild type). The same mutations showed a drastic inhibition effect on F-plasmid transfer, but only in liquid matings, suggesting that previously isolated conjugation-defective mutants do in fact impair mating pair formation in liquid mating, but not conjugative DNA processing or transport per se.We conclude from our genome-wide screen that recipient bacterial cells cannot avoid being used as recipients in bacterial conjugation. This is relevant as an indication of the problems in curbing the dissemination of antibiotic resistance and suggests that conjugation acts as a pure drilling machine, with little regard to the constitution of the recipient cell.Plasmids are self-replicating mobile genetic elements. They are separate from the chromosome and contain a specific subset of genes from the bacterial genetic pool [1,2]. Many plasmids conjugate between different bacteria, especially related ones, leading to intra- and inter-specific dissemination of plasmid-specific genes, for instance, antibiotic resistance genes. As a result, virtually identical plasmids are isolated repetitively in different bacterial species [3,4]. We and others consider that inhibition of plasmid dissemination by inhibiting conjugation might be a useful strategy to enhance or complement the efficacy of antibiotics and curb the isolation of antibiotic resistant bacterial pathogens [5-7]. With this objective in mind, we proposed to learn which genes in the recipient bacteria are needed for the production of transconjugants.In 1968, Curtiss et al. [8] suggested already that conjugation required the active participation of both mating partners. They demonstrated an association between energy metabolism in the F- parent and the rate of chromosome transfer in Hfr × F- matings.
Tratamiento nutricional del fallo intestinal y potenciales mecanismos de estimulación
Pérez de la Cruz,A. J.; Moreno-Torres Herrera,R.; Pérez Roca,C.;
Nutrición Hospitalaria , 2007,
Abstract: severe forms of intestinal failure represent one of the most complex pathologies to manage, in both children and adults. in adults, the most common causes are chronic intestinal pseudo-obstruction and severe short bowel syndrome following large intestinal resections, particularly due to massive mesenteric ischemic, within the context of cardiopathies occurring with atrial fibrillation. the essential management after stabilizing the patient consists in nutritional support, either by parenteral or enteral routes, with tolerance to oral diet being the final goal of intestinal adaptation in these pathologies. surgery may be indicated in some cases to increase the absorptive surface area. parenteral nutrition is an essential support measure that sometimes has to be maintained for long time, even forever, except for technique-related complications or unfavorable clinical course that would lead to extreme surgical alternatives such as intestinal transplantation. hormonal therapy with trophism-stimulating factors opens new alternatives that are already being tried in humans.
Perspectivas en el dise?o y desarrollo de productos para nutrición enteral
Pérez de la Cruz,A. J.; Abilés,J.; Pérez Abud,R.;
Nutrición Hospitalaria , 2006,
Abstract: enteral nutrition is a technique that even though it was used in times immemorial, in the last 25 years has suffered a considerable development, from being considered a secondary therapeutic weapon destined only to feed the patient, to occupying an important status that goes beyond the single act of nourishing. the quantitative composition but overall the qualitative one, is object of an interesting argument in which a profile allowing the modulation of certain aspects of the organism response through the supplementation with different nutrients is searched. that includes from the keeping of the intestinal trophism and of the anti-bacteria intestinal barrier, so important to avoid the frightening multiple organ dysfunction, up to the lessening of the systemic response inflammatory syndrome (sris), going through the immuno-modulative feeding concepts, specific- feeding, pharmaco-nutrient or eco-nutrition. in this new dynamic not only certain nutrients such as glutamine, arginine, nucleotides, ω-3 fatty acids and many antioxidants have acquired importance, but also the manipulation of other molecules of a non- nutritional nature, such as hormones, cytokines and blockers. these aspects that imply passionate ways of investigation for the future are born from the better knowledge that is being acquired from such a severe pathophysiology processes such as sepsis and the organism response before fast and severe aggression; therefore, the modulation of that response through changes in the quantitative and qualitative formulas composition is being attempted.
Perspectivas en el dise o y desarrollo de productos para nutrición enteral Perspectives in the design and development of new products for enteral nutrition
A. J. Pérez de la Cruz,J. Abilés,R. Pérez Abud
Nutrición Hospitalaria , 2006,
Abstract: La Nutrición Enteral es una técnica que aunque utilizada desde tiempos inmemoriales, ha sido en los últimos 25 a os cuando ha experimentado un desarrollo considerable, pasando de ser un elemento terapéutico secundario, destinado exclusivamente a alimentar al paciente, a ocupar en la actualidad un papel importante que va mucho más allá del simple acto de nutrir. La composición cuantitativa pero sobre todo la cualitativa, es objeto de un interesante debate en el que se busca un perfil que permita modular determinados aspectos de la respuesta del organismo mediante el enriquecimiento con distintos nutrientes. Ello incluye desde el mantenimiento del trofismo intestinal y de la "barrera intestinal" antibacteriana, tan importante para prevenir el temido fracaso multiórgánico, hasta la atenuación del Síndrome de la Respuesta Inflamatoria Sistémica, pasando por los conceptos de alimentación inmunomoduladora, alimentación organoespecífica, farmaconutrientes o econutrición. En ésta nueva dinámica han adquirido importancia determinados nutrientes como la glutamina, arginina, nucleótidos, ácidos grasos de la serie ω-3 y antioxidantes diversos, así como la manipulación de otras moléculas de naturaleza no nutricional, como hormonas, factores de crecimiento, citoquinas y bloqueantes. Estos aspectos que suponen para el futuro unas apasionantes vías de investigación, nacen del mejor conocimiento que se va teniendo de la fisiopatología de procesos tan graves como la sepsis, y de la reacción del organismo ante el ayuno y la agresión grave, de modo que se está intentando modular dicha respuesta a través de cambios en la composición cuantitativa y cualitativa de las fórmulas. Enteral nutrition is a technique that even though it was used in times immemorial, in the last 25 years has suffered a considerable development, from being considered a secondary therapeutic weapon destined only to feed the patient, to occupying an important status that goes beyond the single act of nourishing. The quantitative composition but overall the qualitative one, is object of an interesting argument in which a profile allowing the modulation of certain aspects of the organism response through the supplementation with different nutrients is searched. That includes from the keeping of the intestinal trophism and of the anti-bacteria intestinal barrier, so important to avoid the frightening multiple organ dysfunction, up to the lessening of the Systemic Response Inflammatory Syndrome (SRIS), going through the immuno-modulative feeding concepts, specific- feeding, pharmaco-nutrient or eco-nutritio
Tratamiento nutricional del fallo intestinal y potenciales mecanismos de estimulación Nutritional management of intestinal failure and potential stimulation mechanisms
A. J. Pérez de la Cruz,R. Moreno-Torres Herrera,C. Pérez Roca
Nutrición Hospitalaria , 2007,
Abstract: El Fallo Intestinal en sus formas graves representa una de las patologías de manejo más complejo, tanto en ni os como adultos. En adultos las causas más frecuentes son la Pseudoobstrucción Intestinal Crónica y el Síndrome del Intestino Corto severo que sigue a las grandes resecciones intestinales, sobre todo las debidas a isquemia mesentérica masiva, en el marco de cardiopatías que cursan con fibrilación auricular. El tratamiento fundamental tras la estabilización del paciente, está representado por el soporte nutricional por las vías parenteral y/o enteral, constituyendo la tolerancia a la dieta oral, el éxito final de la adaptación intestinal en estos procesos. La cirugía puede estar indicada en algunos casos para incrementar la superficie absortiva. La Nutrición Parenteral es una medida de apoyo fundamental, que a veces hay que mantener durante un tiempo prolongado, e incluso adquirir carácter permanente, salvo que complicaciones ligadas a la técnica, o la evolución clínica desfavorable, obliguen a alternativas quirúrgicas extremas como el trasplante intestinal. El tratamiento hormonal con factores estimulantes del trofismo abre nuevas alternativas que ya se están ensayando en humanos. Severe forms of intestinal failure represent one of the most complex pathologies to manage, in both children and adults. In adults, the most common causes are chronic intestinal pseudo-obstruction and severe short bowel syndrome following large intestinal resections, particularly due to massive mesenteric ischemic, within the context of cardiopathies occurring with atrial fibrillation. The essential management after stabilizing the patient consists in nutritional support, either by parenteral or enteral routes, with tolerance to oral diet being the final goal of intestinal adaptation in these pathologies. Surgery may be indicated in some cases to increase the absorptive surface area. Parenteral nutrition is an essential support measure that sometimes has to be maintained for long time, even forever, except for technique-related complications or unfavorable clinical course that would lead to extreme surgical alternatives such as intestinal transplantation. Hormonal therapy with trophism-stimulating factors opens new alternatives that are already being tried in humans.
Un algoritmo genético para un problema de horarios con restricciones especiales
Pérez de la Cruz,Carlos; Ramírez Rodríguez,Javier;
Revista de Matemática Teoría y Aplicaciones , 2011,
Abstract: ramírez (2001) introduced the generalized robust coloring problem (grcp), this problem lets solve timetabling problems which considers constraints such as: two events can not be assigned at the same time and there must be at least d days between two events. the grcp deals with a robust coloring for a given graph with a fixed number of colors, not necessarily the chromatic number and considers the distance between colors as the penalization of complementary edges. it was shown that the problem is np-complete, so it is necessary to use approximate methods to find good solutions in a reasonable time. this paper presents a hybrid of a genetic algorithm with a local search for cases of 30-120 hours per week; it is shown that for some cases the found solution is optimal and in other cases the solutions are very promising.
Un algoritmo genético para un problema de horarios con restricciones especiales A genetic algorithm in a schedule problem with special constraints
Carlos Pérez de la Cruz,Javier Ramírez Rodríguez
Revista de Matemática Teoría y Aplicaciones , 2011,
Abstract: En Ramírez (2001) se introdujo el problema de coloracion robusta generalizado (PCRG), el cual resuelve problemas de horarios que consideran restricciones del tipo: dos eventos no pueden realizarse a la misma hora y debe haber al menos d días entre dos eventos. El PCRG es una coloración robusta, en que dada una gráfica y un número fijo de colores, no necesariamente el número cromático, considera la distancia entre colores como penalización de las aristas complementarias. Se demostró que el problema es NP-Completo, por lo que es necesario utilizar métodos aproximados para encontrar buenas soluciones en un tiempo razonable. En este trabajo se presenta un híbrido de un algoritmo genético con uno de búsqueda local para casos de 30 a 120 horas por semana, se demuestra que para algunos la solución es óptima y en otros se encuentran soluciones muy prometedoras. Ramírez (2001) introduced the generalized robust coloring problem (GRCP), this problem lets solve timetabling problems which considers constraints such as: two events can not be assigned at the same time and there must be at least d days between two events. The GRCP deals with a robust coloring for a given graph with a fixed number of colors, not necessarily the chromatic number and considers the distance between colors as the penalization of complementary edges. It was shown that the problem is NP-complete, so it is necessary to use approximate methods to find good solutions in a reasonable time. This paper presents a hybrid of a genetic algorithm with a local search for cases of 30-120 hours per week; it is shown that for some cases the found solution is optimal and in other cases the solutions are very promising.
El proyecto de El Berrocal: síntesis preliminar
Rivas, P.,Pérez del Villar, L.,de la Cruz, B.,Gómez, P.
Estudios Geologicos , 1993, DOI: 10.3989/egeol.93493-4348
Abstract: El Berrocal is an international research project on the natural radionuclide migration in a fissured granitic environment. This project is being carried out in the El Berrocal zone, north of the village of Nombela (Toledo). The gelogical formation studied is a granitic pluton with an epithermal vein-type mineralization comprising quartz, sphalerite, pyrite and chalcopyrite; and pitchblende, pyrite, carbonates and barite. The activities of the project are focused on the structural, lithological, geochemical, hydrochemical and hydrogeological aspects of the granite-U mineralization system, in order to establish a migration model of the natural radionuclides of the environment. The concurrence of the tectonic, hydrothermal and supergenic processes has originated several U remobilizations during the deuteric, hydrothermal and supergenic alteration phases, which affected the system. These phases are responsible of the mineralogical species and present distribution of this element within the system. The Th remobilization is much more limited, due to its different geochemical behavior. The present water-rock interaction processes account for the different types of water existing in the system, which are sulphatic, in the shallowest zones, and calcium bicarbonated in the deepest. The U contents in these waters vary from 1 to 100 ppb. The hydrogeology of the zone is controlled, at a local scale, by the topography and the fracture network, and the mineralized quartz dyke plays a major role on the groundwater flow. The isotopic analyses of the U and Th series in the infill materials seem to indicate recent sorption-desorption U processes and coprecipitation with carbonates. El Berrocal , es un proyecto internacional de investigación sobre la migración de radionucleidos naturales en un medio granítico fisurado. Este proyecto se está desarrollando en la zona de El Berrocal, situada al norte de Nombela (Toledo), en un plutón granítico con una mineralización filoniana epitermal de uranio. El objetivo del proyecto es conocer los aspectos estructurales, litológicos, geoquímicos, hidroquímicos e hidrogeológicos del sistema granito-mineralización de U, a fin de establecer un modelo de migración de los radionucleidos naturales del medio. La convergencia de procesos tectónicos, hidrotermales y supergénicos ha dado lugar a sucesivas removilizaciones del uranio durante las fases deutérica, hidrotermal y supergénica, que afectaron al sistema. Estas fases son las responsables de la mineralogía y distribución actual de dicho elemento en el sistema. La removilización del torio
Vitaminas B y homocisteína en la insuficiencia renal crónica Vitamin B complex and homocysteine in chronic renal failure
C. Sánchez,E. Planells,P. Aranda,A. Pérez de la Cruz
Nutrición Hospitalaria , 2007,
Abstract: Durante la insuficiencia renal crónica ocurren cambios metabólicos, bioquímicos y hormonales que suelen ir acompa ados frecuentemente de estados de malnutrición. En pacientes en prediálisis, conocer el estado nutricional en vitaminas hidrosolubles como la tiamina, riboflavina, piridoxina, cianocobalamaina y ácido fólico cobra cada vez más importancia ya que algunas de las manifestaciones de la insuficiencia renal crónica podrían deberse a la deficiencia de algunas de estas vitaminas hidrosolubles. Las rutas metabólicas en las que participan la mayoría de ellas se encuentran interrelacionadas y resulta complejo comprender de qué manera afecta individualmente la deficiencia de cada vitamina a la patología renal. Este trabajo trata de revisar no sólo este aspecto, sino también el estatus en estas vitaminas hidrosolubles que diferentes autores han encontrado en grupos de pacientes en prediálisis. Por otra parte se aborda la problemática de la elevada prevalencia de hiperhomocisteinemia en la insuficiencia renal crónica como principal factor de riesgo de mortalidad por patologías cardiovasculares, así como la implicación de las vitaminas objeto de esta revisión en el metabolismo de la homocisteína y por consiguiente en los niveles plasmáticos de dicho metabolito en pacientes en prediálisis. Metabolic, biochemical, and hormonal changes occur in chronic renal failure usually associated with hyponutrition states. In predialysis patients, knowing the nutritional state about water-soluble vitamins such as thiamine, riboflavin, pyridoxine, cianocobalamine, and folic acid is becoming more and more important since some of the manifestations of chronic renal failure may be due to the deficiency of some of these water-soluble vitamins. The metabolic pathways in which most of these vitamins participate are interrelated and it is difficult to understand how the individual deficits of each vitamin affect renal pathology. This work aims at reviewing not only this issue but also the status of these water-soluble vitamins that different authors have found in groups of predialysis patients. On the other hand, the issue on the high prevalence of hyperhomocysteinemia in chronic renal failure as the main mortality risk factor due to cardiovascular pathologies as well as the implication of these vitamins in the metabolism of homocysteine, and consequently in plasma levels of this metabolite in predialysis patients is reviewed.
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