Reproducción humana asistida : los problemas que suscita desde la bioética y el derecho

El artículo trata de los problemas éticos y jurídicos que surgen a raíz de la puesta en práctica de técnicas de reproducción asistida, al querer determinar la paternidad o poder elegir el sexo de un embrión viable, entre otros.The article deals with the ethical and juridical problems derived from the implementation of assisted reproduction techniques in determining paternity a the sex of au embryo, among other questions

Membrane Permeabilization by Oligomeric α-Synuclein: In Search of the Mechanism

Background: \ud The question of how the aggregation of the neuronal protein α-synuclein contributes to neuronal toxicity in Parkinson's disease has been the subject of intensive research over the past decade. Recently, attention has shifted from the amyloid fibrils to soluble oligomeric intermediates in the α-synuclein aggregation process. These oligomers are hypothesized to be cytotoxic and to permeabilize cellular membranes, possibly by forming pore-like complexes in the bilayer. Although the subject of α-synuclein oligomer-membrane interactions has attracted much attention, there is only limited evidence that supports the pore formation by α-synuclein oligomers. In addition the existing data are contradictory.\ud \ud Methodology/Principal Findings:\ud Here we have studied the mechanism of lipid bilayer disruption by a well-characterized α-synuclein oligomer species in detail using a number of in vitro bilayer systems and assays. Dye efflux from vesicles induced by oligomeric α-synuclein was found to be a fast all-or-none process. Individual vesicles swiftly lose their contents but overall vesicle morphology remains unaltered. A newly developed assay based on a dextran-coupled dye showed that non-equilibrium processes dominate the disruption of the vesicles. The membrane is highly permeable to solute influx directly after oligomer addition, after which membrane integrity is partly restored. The permeabilization of the membrane is possibly related to the intrinsic instability of the bilayer. Vesicles composed of negatively charged lipids, which are generally used for measuring α-synuclein-lipid interactions, were unstable to protein adsorption in general.\ud \ud Conclusions/Significance:\ud The dye efflux from negatively charged vesicles upon addition of α-synuclein has been hypothesized to occur through the formation of oligomeric membrane pores. However, our results show that the dye efflux characteristics are consistent with bilayer defects caused by membrane instability. These data shed new insights into potential mechanisms of toxicity of oligomeric α-synuclein species

Consensus guidelines for the use and interpretation of angiogenesis assays

The formation of new blood vessels, or angiogenesis, is a complex process that plays important roles in growth and development, tissue and organ regeneration, as well as numerous pathological conditions. Angiogenesis undergoes multiple discrete steps that can be individually evaluated and quantified by a large number of bioassays. These independent assessments hold advantages but also have limitations. This article describes in vivo, ex vivo, and in vitro bioassays that are available for the evaluation of angiogenesis and highlights critical aspects that are relevant for their execution and proper interpretation. As such, this collaborative work is the first edition of consensus guidelines on angiogenesis bioassays to serve for current and future reference

The First World War and Coal Trade Geography in Latin America and the Caribbean, 1890-1930

This paper aims to illustrate the dynamics of coal trade between Latin America and its main trade partners, i.e., the USA, Great Britain, and Germany, before and after the enormous disruption caused by the First World War. The coal trade was used as an indicator of modernization for Latin American countries, given that oil was at that time of secondary importance. Energy imports have determined the possibilities of each Latin American country in its process of development. Here, we address this question and place special emphasis on supply channels, concluding that the trade link with main suppliers was of key significance. Although this was very clear by the end of the period, the process had started well before the First World War, at least for the majority of LA&C countries. These points are developed through a gravity model applied to the bilateral coal trade. The importance of the market supplier share is addressed through cluster methodologies

Membrane interactions of oligomeric alpha-synuclein: potential role in Parkinson's disease

alpha-Synuclein is a small neuronal protein that has been implicated to play an important role in Parkinson's disease. Genetic mutations and multiplications in the alpha-synuclein gene can cause familial forms of the disease. In aggregated fibrillar form, alpha-synuclein is the main component of Lewy bodies, the intraneuronal inclusion bodies characteristic of Parkinson's disease. The loss of functional dopaminergic neurons in Parkinson's disease may be caused by a gain in toxic function of the protein. Elucidating if this gain of toxic function is related to the aggregation of alpha-synuclein may be vital in understanding Parkinson's disease. Although there are many ideas on how alpha-synuclein could be involved in the disease, this review will focus on the amyloid pore hypothesis. This hypothesis assumes that aggregation intermediates or oligomers are more likely to be toxic than monomeric or fibrillar forms of the protein. Oligomeric species are thought to exercise their toxicity through permeabilization of cellular membranes. Membrane pore formation by an oligomeric intermediate might play a role in other neurodegenerative disorders in which protein aggregation and amyloid formation play a role, such as Alzheimer's disease. We will discuss the role of this hypothesis in Parkinson's disease

Soap bubbles for large-scale PIV in industrial wind tunnels

This work evaluates the use of helium-filled soap bubbles (HFSB) for Particle Image Velocimetry (PIV) measurements at high Reynolds numbers (up to 3.2 million) in aeronautics. The measurements are performed in the Low Speed Tunnel (LST) of the German-Dutch Wind Tunnels (DNW) using a high-lift airfoil in close-to-stall conditions up to 70 m/s. Experiments using Di-ethylhexyl- sebacat (DEHS) particles are performed for a comparison of the two seeding techniques. The signal to noise ratio of HFSB images was two orders of magnitude larger than that of DEHS, which strongly reduced the unwanted effects of background reflections and light intensity spatial variations, compared to DEHS particle images. The mean velocity field obtained with HFSB exhibits differences typically within 1% of the free stream velocity, when compared to DEHS measurements.Aerodynamics, Wind Energy & PropulsionAerodynamic