Effect of polymer architecture on Curcumin 1 encapsulation and release from PEGylated polymer nanoparticles: toward a drug delivery nano-platform to the CNS

We developed a nanoparticles (NPs) library from poly(ethylene glycol)–poly lactic acid comb-like polymers with variable amount of PEG. Curcumin was encapsulated in the NPs with a view to develop a delivery platform to treat diseases involving oxidative stress affecting the CNS. We observed a sharp decrease in size between 15 and 20% w/w of PEG which corresponds to a transition from a large solid particle structure to a “micelle-like” or “polymer nano-aggregate” structure. Drug loading, loading efficacy and release kinetics were determined. The diffusion coefficients of curcumin in NPs were determined using a mathematical modeling. The higher diffusion was observed for solid particles compared to “polymer nano-aggregate” particles. NPs did not present any significant toxicity when tested in vitro on a neuronal cell line. Moreover, the ability of NPs carrying curcumin to prevent oxidative stress was evidenced and linked to polymer architecture and NPs organization. Our study showed the intimate relationship between the polymer architecture and the biophysical properties of the resulting NPs and sheds light on new approaches to design efficient NP-based drug carriers.

Constitución e Integración

Este libro recoge las actas del coloquio constitución e integración organizado en París los días 3 y 4 de junio de 2005, por la Asociation Adrés Bello de juistes frano-lationaméricains. El tema central aborda la tendencia integracionista ampliamente desarrollada en la segunda mitad del siglo XX, la cual ha influido las constituciones modernas en la previsión de disposiciones que permiten la atribución de ciertas competencias, anteriormente consideradas como exclusivas de la soberanía del Estado, a órganos supranacionales. Es así como, inicialmente en materia económica y luego en otras materias, la integración ha generado la creación de entes supranacionales encargados no sólo de establecer las políticas necesarias para que la integración sea viable, sino también para establecer las normas necesarias para que dicha política sea una realidad. Esta situación presenta un fuerte impacto sobre la estructura jurídica tradicional del Estado. En dicho caso la Constitución deja de ser un marco jurídico rígido para convertirse en un elemento flexible; la Unión Europea es un ejemplo clave de este fenómeno. Múltiples interrogantes surgen entonces con respecto de la jerarquía de normas y de la supremacía de la Constitución frente a los tratados de integración.

Análisis de la incidencia de la política de descentralización en la prestación del servicio de agua potable y saneamiento básico en el Chocó. Periodo 1986 - 1996

El presente trabajo pretende analizar los cambios institucionales, administrativos y de gestión producidos en el sector de agua potable y saneamiento básico en el Departamento del Chocó, a causa de las reformas impulsadas por la política de descentralización y sus distintos procesos entre 1986 y 1996 que se caracterizaron por combinar formas de centralización y descentralización con el ánimo de coordinar y generar colaboración y responsabilidades mutuas entre los distintos niveles de gobierno, dentro del enfoque de la inserción del “agua” como un derecho constitucional a partir de 1991.

Tratamiento nasoangiofibroma juvenil revisión sistemática de reportes de casos

El nasoangiofibroma juvenil es tumor histológicamente benigno, pero potencialmente dañino debido a su rápido crecimiento, y a su posible extensión tracraneal. Tiene tendencia a crecer y extenderse por los forámenes y fisuras naturales. Existen en el momento múltiples clasificaciones y múltiples tratamientos, el principal de ellos es el quirúrgico el cual reporta tasas de recaída hasta del 42 % (Sánchez de Guzmán, Instituto Nacional de Cancerología 2001) y mas de 55 técnicas de abordaje. Se realizaron búsquedas en las siguientes bases de datos: medline, cochrane, proquest, ovid, biblioteca virtual en salud y búsqueda manual.

¿Pluralismo o colonialidad médica? Un estudio alrededor del cáncer en diferentes sistemas médicos colombianos

En esta investigación se realiza un análisis del tipo de relaciones que se establecen entre la medicina alopática y la medicina indígena yagecera en el escenario urbano de Bogotá. Para ello, toma distancia de los estudios ya realizados sobre este tema en el campo de la antropología a partir de dos aspectos: en primer lugar, busca acercarse a esta relación a partir de las trayectorias profesionales de un conjunto de médicos (tanto indígenas como alopáticos); en segundo lugar, se aproxima a estas relaciones a partir de una enfermedad particular: el cáncer.

Didáctica del francés : el diseño del currículo de francés lengua extranjera en la Educación Secundaria Obligatoria y el Bachillerato : aspectos metodológicos y técnicos.

Bibliografía al final de los capítulos. Resumen basado en el de la publicación

Francés : complementos de formación disciplinar : la configuration du curriculum du français langue étrangère dans l´enseignement secondaire obligatoire et le baccalauréat : aspects théorico-conceptuels.

Bibliografía al final de los capítulos

Aide personnalisée et cles de la culture scolaire: une interpellation de certains principes en didactique et formation

L’objectif est de montrer que, naissent parfois pour gérer les hétérogénéités scolaires des propositions de nature à remettre en cause divers schèmes sur lesquels reposent des représentations usuelles des savoirs et de leur transmission, de la structure de l’intervention didactique et de la formation des enseignants

Localization of deep water formation: role of atmospheric moisture transport and geometrical constraints on ocean circulation

A series of coupled atmosphere–ocean–ice aquaplanet experiments is described in which topological constraints on ocean circulation are introduced to study the role of ocean circulation on the mean climate of the coupled system. It is imagined that the earth is completely covered by an ocean of uniform depth except for the presence or absence of narrow barriers that extend from the bottom of the ocean to the sea surface. The following four configurations are described: Aqua (no land), Ridge (one barrier extends from pole to pole), Drake (one barrier extends from the North Pole to 35°S), and DDrake (two such barriers are set 90° apart and join at the North Pole, separating the ocean into a large basin and a small basin, connected to the south). On moving from Aqua to Ridge to Drake to DDrake, the energy transports in the equilibrium solutions become increasingly “realistic,” culminating in DDrake, which has an uncanny resemblance to the present climate. Remarkably, the zonal-average climates of Drake and DDrake are strikingly similar, exhibiting almost identical heat and freshwater transports, and meridional overturning circulations. However, Drake and DDrake differ dramatically in their regional climates. The small and large basins of DDrake exhibit distinctive Atlantic-like and Pacific-like characteristics, respectively: the small basin is warmer, saltier, and denser at the surface than the large basin, and is the main site of deep water formation with a deep overturning circulation and strong northward ocean heat transport. A sensitivity experiment with DDrake demonstrates that the salinity contrast between the two basins, and hence the localization of deep convection, results from a deficit of precipitation, rather than an excess of evaporation, over the small basin. It is argued that the width of the small basin relative to the zonal fetch of atmospheric precipitation is the key to understanding this salinity contrast. Finally, it is argued that many gross features of the present climate are consequences of two topological asymmetries that have profound effects on ocean circulation: a meridional asymmetry (circumpolar flow in the Southern Hemisphere; blocked flow in the Northern Hemisphere) and a zonal asymmetry (a small basin and a large basin).

Controlling spurious diapycnal mixing in eddy-resolving height-coordinate ocean models: insights from virtual deliberate tracer release experiments

A perceived limitation of z-coordinate models associated with spurious diapycnal mixing in eddying, frontal flow, can be readily addressed through appropriate attention to the tracer advection schemes employed. It is demonstrated that tracer advection schemes developed by Prather and collaborators for application in the stratosphere, greatly improve the fidelity of eddying flows, reducing levels of spurious diapycnal mixing to below those directly measured in field experiments, ∼1 × 10−5 m2 s−1. This approach yields a model in which geostrophic eddies are quasi-adiabatic in the ocean interior, so that the residual-mean overturning circulation aligns almost perfectly with density contours. A reentrant channel configuration of the MIT General Circulation Model, that approximates the Antarctic Circumpolar Current, is used to examine these issues. Virtual analogs of ocean deliberate tracer release field experiments reinforce our conclusion, producing passive tracer solutions that parallel field experiments remarkably well.

Markers for nutrition studies: review of criteria for the evaluation of markers

The following criteria were identified as essential elements in the evaluation of markers: (1) the marker has a causal biological link with the endpoint, (2) there is a significant association between marker and endpoint in the target population, (3) marker changes consistently with the endpoint, e.g., in response to an intervention, and (4) change in the marker explains a substantial proportion of the change in the endpoint in response to the intervention.

Dietary levels of pure flavonoids improve spatial memory performance and increase hippocampal brain-derived neurotrophic factor.

Evidence suggests that flavonoid-rich foods are capable of inducing improvements in memory and cognition in animals and humans. However, there is a lack of clarity concerning whether flavonoids are the causal agents in inducing such behavioral responses. Here we show that supplementation with pure anthocyanins or pure flavanols for 6 weeks, at levels similar to that found in blueberry (2% w/w), results in an enhancement of spatial memory in 18 month old rats. Pure flavanols and pure anthocyanins were observed to induce significant improvements in spatial working memory (p = 0.002 and p = 0.006 respectively), to a similar extent to that following blueberry supplementation (p = 0.002). These behavioral changes were paralleled by increases in hippocampal brain-derived neurotrophic factor (R = 0.46, p<0.01), suggesting a common mechanism for the enhancement of memory. However, unlike protein levels of BDNF, the regional enhancement of BDNF mRNA expression in the hippocampus appeared to be predominantly enhanced by anthocyanins. Our data support the claim that flavonoids are likely causal agents in mediating the cognitive effects of flavonoid-rich foods.