Ephrin-B2 reverse signaling increases α5ß1 integrin-mediated fibronectin deposition and reduces distal lung compliance.

Alveolar growth abnormalities and severe respiratory dysfunction are often fatal. Identifying mechanisms that control epithelial proliferation and enlarged, poorly septated airspaces is essential in developing new therapies for lung disease. The membrane-bound ligand ephrin-B2 is strongly expressed in lung epithelium, and yet in contrast to its known requirement for arteriogenesis, considerably less is known regarding the function of this protein in the epithelium. We hypothesize that the vascular mediator ephrin-B2 governs alveolar growth and mechanics beyond the confines of the endothelium. We used the in vivo manipulation of ephrin-B2 reverse signaling to determine the role of this vascular mediator in the pulmonary epithelium and distal lung mechanics. We determined that the ephrin-B2 gene (EfnB2) is strongly expressed in alveolar Type 2 cells throughout development and into adulthood. The role of ephrin-B2 reverse signaling in the lung was assessed in Efnb2(LacZ/6YFΔV) mutants that coexpress the intracellular truncated ephrin-B2-ß-galactosidase fusion and an intracellular point mutant ephrin-B2 protein that is unable to become tyrosine-phosphorylated or to interact with either the SH2 or PDZ domain-containing downstream signaling proteins. In these viable mice, we observed pulmonary hypoplasia and altered pulmonary mechanics, as evidenced by a marked reduction in lung compliance. Associated with the reduction in lung compliance was a significant increase in insoluble fibronectin (FN) basement membrane matrix assembly with FN deposition, and a corresponding increase in the α5 integrin receptor required for FN fibrillogenesis. These experiments indicate that ephrin-B2 reverse signaling mediates distal alveolar formation, fibrillogenesis, and pulmonary compliance.

Funcionamiento cognitivo de niños entre 4 y 6 años para la resolución de conflictos interpersonales / Cognitive Functioning of Children Aged 4 to 6 in Interpersonal Conflict Resolution

Esta investigación se centra en el estudio de aspectos del funcionamiento cognitivo de los niños en el dominio del conocimiento social, partiendo del uso de Situaciones de Resolución de Problemas (SRP). Se busca indagar la forma en la cual los niños resuelvan conflictos interpersonales y utilicen la toma de perspectiva como habilidad social. El objetivo general del proyecto es describir los funcionamientos cognitivos de 20 niñas y niños entre cuatro y seis años de edad, para la resolución de conflictos interpersonales, a través de los desempeños obtenidos en una tarea, que simula tres escenarios con situaciones de disputa entre varios personajes. Los resultados demuestran que los niños en edad escolar son capaces de incorporar habilidades sociales desde edades tempranas. Este hecho sustenta la idea de que el desarrollo cognitivo, especialmente en el dominio social, no requiere de un funcionamiento general, sino que presenta variabilidad en periodos cortos de tiempo respecto a la resolución de conflictos interpersonales, e incluso en micro momentos dentro de la misma tarea.

This article focuses on children cognitive Functioning in the social domain of knowledge. It is based on the use of problem solving tasks (PST), using a social skills perspective, to investigate the way in which children solve interpersonal conflicts. The project's overall objective is to describe the cognitive functioning of 20 children between four and sixth years of age, for interpersonal conflicts solving, through the performances obtained in a task that simulates three scenarios where there are disputes between various characters. The results show that school-age children are able to incorporate social skills from an early age and support the idea that cognitive development, especially in the social domain, does not require an overall functioning, but show variability in short periods of time compared to solving interpersonal conflicts, and even within the same task's micro moments.

Effects of maternal magnesium sulfate administration on intestinal blood flow velocity in preterm neonates.

BACKGROUND: Antenatal MgSO4 administration is used extensively as a tocolytic agent and to treat preeclampsia. Various effects on the fetus and newborn have been reported, and MgSO4 has well-documented vasoactive effects. OBJECTIVE: To determine if antenatal MgSO4 administration affects intestinal blood flow velocity in newborn preterm infants. METHODS: Peak, mean and end-diastolic velocities in the superior mesenteric artery were measured on day 1 of life. Maternal medical records were reviewed to identify infants whose mothers had been administered MgSO4 for preterm labor or preeclampsia within 24 h of delivery. RESULT: Fifty-six infants were studied: 27 were exposed and 29 were not exposed to antenatal MgSO4. Mean birth weight (1,371 ± 349 and 1,401 ± 469 g, respectively), gestational age (29.7 ± 2.0 and 30.0 ± 2.9 weeks, respectively) and infant hemodynamic and clinical variables (other than clinical indication for antenatal MgSO4 administration) were similar between groups. There were no significant differences between the exposed and unexposed groups in intestinal blood flow velocities. For the exposed group, however, there was a significant negative correlation between mean velocity and the number of hours from birth to the time superior mesenteric artery blood flow velocity measurements were made (p = 0.002); there was no correlation for the unexposed group (p = 0.852). CONCLUSION: Group mean values indicate that antenatal exposure to MgSO4 does not significantly affect intestinal blood flow velocity in newborn preterm infants. However, the significant negative relationship between mean blood flow velocity and time from birth to blood flow velocity measurement in exposed infants suggests that there may be measurable effects of MgSO4 exposure within the hours immediately after birth. Trials that prospectively evaluate the development of intestinal blood flow velocities are needed to further clarify potential effects of antenatal MgSO4 on the gastrointestinal tract of preterm infants.