Current Status in Peripheral Nerve Xenotransplantation

Nerve grafts are used to repair segmental defects in peripheral nerves. However, autografts and even allografts are limited for clinical use. Xenotransplantation offers a potentially unlimited source for tissue transplantation. We have conducted a systematic review of the literature, aiming to clarify the latest and more appealing proposals and discoveries in nerve xenotransplantation. A total of 22 articles were retrieved, all of them experimentally controlled studies in animals. There are no current studies in humans. Fresh xenografts provoke an immune response that leads to graft rejection. Immunosuppressive drugs or pretreatment of the grafts are the preferred methods against immune rejection. Recently, investigative groups have proposed the use of acellular nerve xenografts, which do not elicit immune rejection while they do allow and promote axonal regeneration. The addition of human stem cells increases nerve growth. Limits to the analyzed studies are the absence of trials in humans and the short length of the nerve defects that have been successfully repaired. Further investigations and clinical trials are needed before nerve xenografting is accepted as a valid method of nerve repair

Recomendações para utilização do microtomógrafo de raios-X Sky Scan 1172 em ciências agrárias e biológicas.

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Microtomógrafo de raios-X para aplicações agrícolas e biológicas.

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Machera : transfiguraciones visuales de un héroe merideño

Este trabajo es un registro y un análisis del proceso de transcodificación producido entre los relatos del imaginario social sobre la figura de un personaje real de la historia social de la ciudad de Mérida (Venezuela) y una serie de cómics. Todo este proceso incorpora transformaciones previas en el establecimiento del valor significante de este personaje antes y después de la elaboración de la historieta. Desde los hechos reales y su interpretación a nivel del imaginario social, hasta la configuración visual del cómic, este trabajo se propone un registro analítico de la semiosis visual como transposición de un relato oral

Distribución geográfica y estado de conservación de los peces sierra Pristis spp (Pristiformes: Pristidae) en el Caribe sur

The former presence of sawfishes (Pristis spp) is confirmed for the southern Caribbean Sea from the coasts of Colombia and Venezuela, based on review of eleven rostral saws exhibited in businesses, museums and private collections, as well as bibliographic references, photographs and surveys to detect sightings or captures in both countries. We determined that Pristis pristis and Pristis pectinata were present in the southern Caribbean coasts of Colombia and Venezuela, but that they are now probably locally extinct.Se confirma la presencia en el pasado de las especies de pez sierra (Pristis spp) en el mar Caribe de Colombia y Venezuela, a partir de la revisión de once extensiones rostrales exhibidas en establecimientos, museos y colecciones de particulares, así como la consulta bibliográfica, encuestas y el examen de material fotográfico disponible sobre avistamientos o capturas realizadas en ambos países. Se determinó que las especies presentes en el Caribe de Colombia y Venezuela eran Pristis pristis y Pristis pectinata, las cuales en la actualidad se encuentran probablemente extintas localmente

Produção de matéria seca de alfafa com uso de resíduos de construção e demolição reciclados (RCD-R) como corretivo da acidez do solo.

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H2 production from bioethanol and its use in fuel-cells

Bioethanol was considered as raw material for hydrogen production by steam reforming, coupled with a proton exchange membrane fuel cell for heat and power cogeneration (5 kWelectrical + 5 kWthermal). The water/ethanol feeding ratio and the ethanol purity were considered for process optimisation. An increase of the water/ethanol ratio improved H2 yield at the expenses of higher heat input to the reformer and lower electrical output. However, the presence of a high enthalpy exhaust stream increased the available thermal output, with a consequent increase of the thermal and overall efficiency of the plant. Finally, the bioethanol purification step, which is energy- and cost-intensive, has been taken into account, searching for an optimisation of the bioethanol purification strategy for the overall process intensification