Search results for "Transporte"
showing 10 items of 743 documents
L‐Aspartate as a high‐quality nitrogen source in Escherichia coli : Regulation of L‐aspartase by the nitrogen regulatory system and interaction of L‐…
2020
Escherichia coli uses the C4-dicarboxylate transporter DcuA for L-aspartate/fumarate antiport, which results in the exploitation of L-aspartate for fumarate respiration under anaerobic conditions and for nitrogen assimilation under aerobic and anaerobic conditions. L-Aspartate represents a high-quality nitrogen source for assimilation. Nitrogen assimilation from L-aspartate required DcuA, and aspartase AspA to release ammonia. Ammonia is able to provide by established pathways the complete set of intracellular precursors (ammonia, L-aspartate, L-glutamate, and L-glutamine) for synthesizing amino acids, nucleotides, and amino sugars. AspA was regulated by a central regulator of nitrogen meta…
In vitro evaluation of glycol chitosan based formulations as oral delivery systems for efflux pump inhibition.
2017
Recently, we have reported that glycol chitosan (GCS) was able to reverse the P- glycoprotein (P-gp) efflux pump. The objective of the present study was to evaluate the potential of two GCS-based dosage forms (aqueous solution or nanoparticle suspension) for oral administration of the P-gp substrate Rho-123. A further aim of the present study was to assess the effect of the glycol chitosan-4-thiobutylamidine thiomer (GCS-TBA) on P-gp activity considering that the corresponding thiomer of chitosan series is a well-known P-gp inhibitor. Pre-treatment of Caco-2 cell monolayer with a GCS solution or GCS-based nanoparticles increased the absorptive transport of Rho-123 across the monolayer of 1.…
Multipotential nestin and Isl-1 positive mesenchymal stem cells isolated from human pancreatic islets.
2006
Mesenchymal cells in the developing pancreas express the neural stem cell marker nestin and the transcription factor islet-1 (Isl-1). Using defined culture conditions we isolated on a single cell basis nestin producing cells from human pancreatic islets. These cells were immortalized with lentiviral vectors coding for telomerase and mBmi. They are positive for Isl-1 and nestin and have the potential to adopt a pancreatic endocrine phenotype with expression of critical transcription factors including Ipf-1, Isl-1, Ngn-3, Pax4, Pax6, Nkx2.2, and Nkx6.1 as well as the islet hormones insulin, glucagon, and somatostatin. In addition, they can be differentiated into human albumin producing cells …
Glial Chloride Homeostasis Under Transient Ischemic Stress
2021
High water permeabilities permit rapid adjustments of glial volume upon changes in external and internal osmolarity, and pathologically altered intracellular chloride concentrations ([Cl–]int) and glial cell swelling are often assumed to represent early events in ischemia, infections, or traumatic brain injury. Experimental data for glial [Cl–]int are lacking for most brain regions, under normal as well as under pathological conditions. We measured [Cl–]int in hippocampal and neocortical astrocytes and in hippocampal radial glia-like (RGL) cells in acute murine brain slices using fluorescence lifetime imaging microscopy with the chloride-sensitive dye MQAE at room temperature. We observed s…
Analisi tecnica di cantieri meccanizzati nelle operazioni di utilizzazioni forestali in Sicilia
2005
The authors describe the results of a research performed in a wood of the Western Sicily, covered with Pinus halepensis Mill. and Cupressus sempervirens L. Felling, delimbing, cross-cutting and extraction of the logs were carried out. The wood obtained was used as firewood. Two different methods of logs extraction were carried out: with transporters and with polyethylene timber chutes. The working time and the labour productivity recorded during each operations are reported. The results show that in the forest utilization performed in Sicily the mean labour productivity per operator is 2.4 t of firewood per day. This value fits well the mean value recorded in Italy (2-3 t of firewood per da…
Enhanced transport through binding cooperativity in a circulating system
1991
Abstract Allosteric cooperativity in a multiphase circulating system is shown to enhance ion transport when long contact times are involved.
Interaction of glutamic-acid-rich proteins with the cGMP signalling pathway in rod photoreceptors.
1999
The assembly of signalling molecules into macromolecular complexes (transducisomes) provides specificity, sensitivity and speed in intracellular signalling pathways. Rod photoreceptors in the eye contain an unusual set of glutamic-acid-rich proteins (GARPs) of unknown function. GARPs exist as two soluble forms, GARP1 and GARP2, and as a large cytoplasmic domain (GARP' part) of the beta-subunit of the cyclic GMP-gated channel. Here we identify GARPs as multivalent proteins that interact with the key players of cGMP signalling, phosphodiesterase and guanylate cyclase, and with a retina-specific ATP-binding cassette transporter (ABCR), through four, short, repetitive sequences. In electron mic…
Problemas que plantean las reclamaciones frente a AESA: especial referencia a su naturaleza jurídica e impugnación
2022
EL presente artículo centra su atención en los problemas que plantea la solución extrajudicial de conflictos en el transporte aéreo desde que se aprobara la Ley 7/2017, así como en la introducción del requisito de procedibilidad introducido por el Anteproyecto de Ley de Medidas de Eficiencia Procesal al Servicio Público de Justicia, cuando pretendan ejercitarse acciones judiciales a través de los cauces del juicio verbal al amparo de la normativa de transportes, nacional e internacional. Asimismo, se hace referencia a la naturaleza (seudo)administrativa de la reclamación iniciada por un pasajero frente a AESA, a la atribución de la competencia al orden contencioso-administrativo por el Proy…
Una historia de la psicologia del tráfico y el transporte en Europa.
2003
No se trata de un directori0 de cien años de investigación en los paises europeos; es una perspectiva general, un intento de clasificación empírica de las tendencias cronológicas y una sugerencia para un futuro campo de investigación. Distinguimos, y analizamos en sus principales tendencias, cuatro estadios en el desarrollo de la psicologia del tráfico y el transporte desde el inicio del siglo xx (estadio "psicofisico") hasta nuestros dias (de "asistencia técnica"). La psicologia del tráfico y el transporte recibió un impulso decisivo durante las dos guerras mundiales; también debido al avance del propio transporte, de las politicas de seguridad públicas y de las medidas técnicas y prevent…
Incentives, Service Quality, and Regulation: An Application to the Airline Industry
2012
El sector aéreo presenta interesantes retos para el investigador. Se trata de un sector complicado debido, entre otras características, a las siguientes: escasos márgenes de beneficios, elevadas barreras de entrada y salida, alta sensibilidad a ciclos económicos, y la regulación y competencia. Desde los años 90, Europa ha vivido un proceso de desregulación en el tráfico aéreo. Ello ha supuesto una reorganización de las redes desde rutas completamente conectadas (fully-connected) hacia redes con aeropuertos base (hub-and-spoke). No debemos olvidar que sobreviven mercados que están regulados de acuerdo con la calificación de “obligación de servicio público” – en España tenemos el caso de las …