La hipoxia fetal valorada mediante métodos objetivos y su relación con el Factor de crecimiento del Endotelio Vascular (VEGF) en gestaciones gemelares.

Introducción Para el correcto desarrollo placentario y fetal, se requieren los procesos de vasculogénesis y angiogénesis que están regulados entre otros por la familia VEGF y el Factor de crecimiento placentario (PlGF) que traducen sus señales uniendose a sus receptores transmembrana, el VEGFR1 y 2. El VEGFR1 tiene una forma soluble ( s.Flt-1) que actúa como un inhibidor del VEGF y del PlGF . El VEGF-A es el principal regulador de la angiogénesis siendo el VEGF-121 y VEGF-165 las 2 isoformas más predominantes e importantes, y estando su expresión regulada por la hipoxia. La hipoxia debida a insuficiencia placentaria se observa en gestaciones gemelares con discrepancia ponderal entre los fetos (diferencia entre los pesos fetales superior al 20 o 25%). Conforme la discrepancia se hace más acusada se incrementa la morbilidad perinatal. Hipótesis Si los fetos hipóxicos aumentan los niveles de VEGF aumentando la angiogénesis para compensar dicha hipóxia, la determinación del sistema VEGF en plasma materno podría ser un marcador bioquímico de compromiso fetal. Objetivos - Principal: evaluar la producción, secreción y expresión del sistema VEGF materno en gestaciones gemelares con fetos concordantes y discrepantes, y valorar si este, podría ser un indicador de hipoxia fetal en las mismas. -Secundarios: estudio de la asociación del sistema VEGF con los parámetros objetivos que nos informan del bienestar fetal anteparto (OVF vasos fetales) e intraparto (EAB, peso fetal, placentario y Test de Apgar) y la relación del sistema en el binomio feto-materno. Material y métodos Estudio observacional prospectivo de casos-controles . 64 gestaciones gemelares bicoriales-biamnióticas :13 casos y 51 controles ( discrepancia ponderal 25%), y 21 casos y 43 controles ( discrepancia 20%) Resultados Existe una correlación significativa y positiva entre las semanas de gestación y el sFlt-1, es decir, sus valores aumentan conforme avanza la gestación. Apreciamos que los componentes del sistema VEGF son menores en las gestaciones discrepantes, siendo estadísticamente significativa la diferencia cuando hablamos del VEGF libre y total. Al comparar las diferencias el sistema VEGF en los vasos fetales y la expresión placentaria del VEGF, no se observaron diferencias ni al estudiar los gemelares de forma global ni al comparar el feto de mayor y menor peso. En el feto, encontramos niveles mayores de sFlt- 1 en arteria umbilical a menores pH fetales. No se observa correlación entre la expresión placentaria del VEGF y las OVF maternas ni fetales, ni tampoco con el resto de parámetros que valoran el bienestar fetal. Al analizar el sistema VEGF en el binomio feto-materno, vemos que las concentraciones de VEGF libre y total son superiores en los fetos, en cambio el sFlt-1 es superior en el compartimento materno (p <0,001). Por último, observamos que todos los componentes del sistema VEGF materno se correlacionan con sus homólogos en los vasos fetales de forma significativa y positiva no observándose asociación con el sistema VEGF placentario. Conclusiones La determinación del sistema VEGF en plasma materno a lo largo de la gestación no nos ayuda a diferenciar entre las gestaciones gemelares concordantes y discrepantes, tampoco es útil para el diagnóstico de la hipoxia fetal. Sin embargo, el estudio de las OVF en los vasos fetales es una herramienta útil en las gestaciones gemelares así como el estudio del EAB al nacimiento para valorar el compromiso fetal. Los niveles de sFlt -1 en arteria umbilical fetal se correlacionan con el pH en arteria fetal al nacimiento, lo que sugiere su papel en el mecanismo de adaptación fetal a la hipoxia.Hypothesis: If fetal hypoxia arise VEGF levels increasing angiogenesis to balance hypoxia, maternal serum VEGF could be a biochemical marker of fetal compromise. Objective: Assess VEGF system production, secretion and expression in twin pregnancies with fetal growth discrepancy ( FGD) and its usefullness as fetal hypoxia marker. Study design: Prospective case-control study. 64 dichorionic diamniotic pregnancies: Group A:fetal discrepancy 25%: 13 cases and 51 controls Group B: fetal discrepancy 20%: 21 cases and 43 controls. Outcome: There is a significant and positive correlation between pregnancy weeks and sFlt-1 (soluble form of VEGFR1) We appreciate lower VEGF values system components in discrepant twins,being free and total VEGF statistically significant. . Assessing VEGF system in fetal vessels and placental VEGF expression, we don’t find out differences neither studying globally twin pregnancies nor bigger-smaller twin. sFlt-1 levels in fetal umbilical artery are higher with lower fetal pH. There isn´t correlation between placental VEGF expression and with fetal or maternal flow velocity waveforms ( FVWf),neither with fetal well-being parameters. When analyzing VEGF system in the fetal-maternal binomial, we determine concentrations of free and total VEGF are higher in fetuses, meanwhile sFlt-1 is higher in maternal compartment (p<0.001). Finally, all maternal VEGF components correlate with its fetal vessels counterpart, but with placental VEGF system. Conclusion: Determination of maternal plasma VEGF system throughout pregnancy doesn´t help us to distinguish concordant and discrepant twin pregnancy, although is useful to assess fetal hypoxia. However, fetal vessels FVWf and acid base balance at birth are a useful tool in twins to assess fetal compromise. sFlt -1 levels in fetal umbilical artery correlate with fetal artery pH at birth, suggesting its role in the mechanism of hypoxia fetal adaptation

Photoemission results on intralayer insertion at III-V/III-V junctions: A critical appraisal of the different interpretations

Several researchers have proposed that band discontinuities at semiconductor heterojunctions may be "tuned" by inserting very thin layers of foreign atoms at the interface which are thought to induce an "interface dipole." Modifications of the apparent valence-band offset, as measured by photoelectron spectroscopy (PES), have been indeed observed upon Si insertion at GaAs–AlAs interfaces, and they have been generally interpreted as real band-offset changes. However, there is an alternative explanation of the photoemission results in terms of band-bending effects. Here, we present results of PES experiments designed to test the two opposing interpretations. We have examined the effect of Si insertion at polar (100) and nonpolar (110) interfaces, and we have studied the insertion of Si (n-type) and Be (p-type) intralayers. Similar results are obtained for polar and nonpolar interfaces, and effects of opposite sign are observed for Si and Be intralayers. These results can be readily interpreted in terms of a band-bending profile modification upon Si or Be insertion. Additional PES experiments performed at different substrate temperatures have allowed us to test the proposed band profiles. From the surface photovoltage effects induced at low temperature, we obtain evidence for sample band bending which is consistent with the room-temperature band profiles proposed. Hence, our results can be completely understood within a "band-bending interpretation," calling into question the interpretation in terms of a "band-offset tuning effect.

Si and Be intralayers at GaAs/AlAs and GaAs/GaAs junctions: Low-temperature photoemission measurements

In order to distinguish between conflicting interpretations regarding the effect of intralayer insertion at semiconductor junctions, we have carried out synchrotron-radiation photoemission studies of GaAs/AlAs(100) heterojunctions and GaAs/GaAs(110) homojunctions, with and without a Si or a Be intralayer, at room temperature and at low temperature. The synchrotron light induces photovoltage effects at low temperature, which are found to be consistent with the room-temperature band profiles we have previously proposed for these heterojunctions [M. Moreno et al., Phys. Rev. B 58, 13 767 (1998)], assuming a doping role for the intralayer atoms. Band discontinuities play an important role in determining the type of photovoltage effects induced. Our experimental observations can be fully understood in terms of intralayer-induced changes of the bandbending profile, and the occurrence of photovoltage effects at low temperature, calling into question the previous interpretation of room-temperature photoemission results from GaAs/AlAs heterojunctions in terms of intralayer-induced "band-offset" changes

Rigor científico en películas recientes de catástrofes. Validación de materiales para el profesorado de geología

Estudios previos demuestran que el uso de películas en el aula incrementa la retención de información, aunque su falta de rigor científico debe ser evaluada, evitando integrar errores en la base de conocimiento del alumnado. Películas de los últimos siete años muestran acertadas reconstrucciones de tsunamis pero incluyen errores sobre las áreas de bordes de placa y en la reconstrucción de procesos geológicos. Para este trabajo se prepararon fichas didácticas con escenas de corta duración de tres películas: La Ola (2015), París: infierno helado (2013) y San Andrés (2015). Todas ellas vertebradas en competencias de geología que se repiten en ESO y bachillerato, como son la tectónica de placas y los minerales y rocas, a la vez que relacionadas con otros contenidos del currículo en esos niveles. El objetivo del trabajo fue hacer un análisis científico de los fragmentos seleccionados y una ficha didáctica de cada uno, que presentara actividades adecuadas a los cuatro niveles, 3° y 4° de ESO y 1° y 2° de BAC, donde la geología es materia de estudio en secundaria

Si intralayers at GaAs/AlAs and GaAs/GaAs junctions: Polar versus nonpolar interfaces

The effect of inserting thin Si intralayers at GaAs/AlAs and GaAs/GaAs interfaces has been studied by photoelectron spectroscopy (PES) using synchrotron radiation. Results from polar and nonpolar interfaces are compared by analyzing samples grown by molecular-beam epitaxy on (100) and (110) substrates, respectively. The Si intralayers were inserted by an improved δ-doping method in a concentration of 2.2×1014 cm−2 [about 1/3 of a (100) monolayer]. When Si is introduced at GaAs-on-AlAs interfaces, the Al(2p)-to-Ga(3d) energy distance is observed to increase for both polar and nonpolar interface orientations. The insertion of Si at GaAs/GaAs(110) homojunctions modifies the line shape of the Ga(3d) and As(3d) peaks, resembling the changes previously reported for the (100) orientation. The results on polar junctions previously obtained were generally interpreted as band-offset changes, which would be related according to the “interface microscopic capacitor” picture with the polar nature of the interface. The PES results here presented are difficult to reconcile with such a model because of the similar behavior shown by polar and nonpolar interfaces. Instead, they can be understood within an “overlayer band bending” interpretation

Morphology evolution of thermally annealed polycrystalline thin films

Investigation of the morphology evolution of annealed polycrystalline Au(111) films by atomic force microscopy and x-ray diffraction leads to a continuous model that correlates such an evolution to local interactions between grains triggering different mechanisms of stress accommodation (grain zipping and shear strain) and relaxation (gap filling and grain rotation). The model takes into consideration findings concerning the in-plane reorientation of the grains during the coalescence to provide a comprehensive picture of the grain-size dependence of the interactions (underlying the origin of the growth stress in polycrystalline systems); and in particular it sheds light on the postcoalescence compressive stress as a consequence of the kinetic limitations for the reorientation of larger surface structuresThis paper was supported by the projects F1-54173 (bilateral program CSIC-Conacyt) 200960I182 (CSIC), and CCG10-UAM/MAT-5537 (DGUI-Comunidad de Madrid and Universidad Aut´onoma deMadrid). A.G.G. acknowledges the financial support of the MICINN Spanish Ministry under the project ESP2006-14282-C02-0

The transcriptional activator Gli2 modulates T-cell receptor signalling through attenuation of AP-1 and NFκB activity

Different tissues contain diverse and dynamic cellular niches, providing distinct signals to tissue-resident or migratory infiltrating immune cells. Hedgehog (Hh) proteins are secreted inter-cellular signalling molecules, which are essential during development and are important in cancer, post-natal tissue homeostasis and repair. Hh signalling mediated by the Hh-responsive transcription factor Gli2 also has multiple roles in T-lymphocyte development and differentiation.Here, we investigate the function of Gli2 in T-cell signalling and activation. Gene transcription driven by the Gli2 transcriptional activator isoform (Gli2A) attenuated T-cell activation and proliferation following T-cell receptor (TCR) stimulation. Expression of Gli2A in T-cells altered gene expression profiles, impaired the TCR-induced Ca2+ flux and nuclear expression of NFAT2, suppressed upregulation of molecules essential for activation, and attenuated signalling pathways upstream of the AP-1 and NFκB complexes, leading to reduced activation of these important transcription factors. Inhibition of physiological Hh-dependent transcription increased NFκB activity upon TCR ligation. These data are important for nderstanding the molecular mechanisms of immunomodulation, particularly in tissues where Hh proteins or other Gli-activating ligands such as TGFβ are upregulated, including during inflammation, tissue damage and repair, and in tumour microenvironments

Knowledge of the benefits of physical-sport activity in older people according to socio demographic variables

This investigation pretends to know the degree of knowledge of the benefits of the practice of physical-sports activities for older people in an urban population of over 100,000 inhabitants (Alcalá de Henares) and the relationship according to socio-demographic variables. The quantitative used methodology has consisted of the realization of interviews face to face to a random sample of 133 people over 65 years of this population. The instrument used in the investigation has consisted of a questionnaire with closed questions, already validated in other research studies on the elderly. The results show that most respondents state they are aware of the various benefits of the physical-sports activities, although the psychological benefits are the least known. While according to socio-demographic variables are in general the man, seniors with 74 or fewer years and those with sufficient income those with a higher degree of knowledge.Esta investigación pretende conocer el grado de conocimiento de los beneficios de la práctica de actividad físico-deportiva por las personas mayores de una población urbana de más de 100.000 habitantes (Alcalá de Henares) y su relación según variables socio-demográficas. La metodología cuantitativa empleada ha consistido en la realización de entrevistas estructuradas cara a cara a una muestra aleatoria de 133 mayores de 65 años de esa población. El instrumento utilizado en la investigación ha consistido en un cuestionario con preguntas cerradas ya validado en otros estudios sobre personas mayores. Los resultados muestran que la mayoría de los encuestados manifiestan conocer los diferentes beneficios que aporta la actividad físico-deportiva, aunque los de tipo psicológico son los menos conocidos. Mientras que según variables socio-demográficas son, en general, los hombres, los mayores con 74 o menos años y aquellos con ingresos suficientes los que tienen un mayor grado de conocimiento.Ministerio de Educación y CienciaUniversidad Politécnica de Madri

Historia y magia natural o Ciencia de Filosofía oculta : con nuevas noticias de los mas profundos mysterios, y secretos del universo visible ...

Existe emisión con pie de imp.: En Madrid: por Juan Garcia Infanzon: a costa de Joseph Bazcones, 1692Sign.: [calderón]6, A-Y8, Z3Texto a dos col.Antep.Port. con orla tip