Formation of new capillary blood vessels, termed angiogenesis, is essential for the growth and development of tissues and underlies a variety of diseases including tumor growth. Members of the prolactin hormonal family bind to endothelial cell receptors and have direct effects on cell proliferation, migration and tube formation. Because many angiogenic and antiangiogenic factors are produced by endothelial cells, we investigated whether endothelial cells expressed the prolactin gene. Here we show that bovine brain capillary endothelial cells (BBCEC) in culture express the full-length prolactin messenger RNA, in addition to a novel prolactin transcript, lacking the third exon of the gene. In addition cultures of BBCEC synthesize and secrete prolactin-like immunoreactive proteins with apparent molecular masses of 23, 21 and 14 kDa. The prolactin-like nature of these proteins is supported by the observation that Nb2-cells, a prolactin-responsive cell line, were stimulated to proliferate when co-cultured with endothelial cells and this stimulation was neutralized with prolactin-directed antibodies. Finally, consistent with a possible autocrine effect of endothelial-derived prolactins, polyclonal and monoclonal prolactin antibodies specifically inhibited basal and basic fibroblast growth-factorstimulated growth of endothelial cells. Taken together, the present findings support the hypothesis of the prolactin gene being expressed in endothelial cells as proteins that could act in an autocrine fashion to regulate cell proliferation.
Recent studies in several neuronal lineages suggest that extrinsic factors such as polypeptide growth factors regulate various stages of neuronal development, from initial commitment of multipotent progenitors to induction of specific gene expression that is characteristic of terminal neuronal differentiation. In the present study, immortalized hypothalamic neurons of the GT1-1 lineage were used to analyze proliferative, as well as morphological and molecular differentiation actions of basic fibroblast growth factor (bFGF), epidermal growth factor (EGF), transforming growth factor-alpha (TGF-alpha), and insulin-like growth factor-I (IGF-I). These effects were compared with those induced by specific activators of protein kinase A and C pathways, which potently inhibited cell proliferation and gonadotropin-releasing hormone (GnRH) gene expression, but stimulated morphological neuronal maturation as determined by the length and number of neurite outgrowth. bFGF exerted a broad spectrum of stimulatory effects, increasing the rate of proliferation measured both by the incorporation of 3H-thymidine and by cell number, and parameters of terminal differentiation, such as neurite outgrowth and induction of gene expression. bFGF stimulated the expression of the hybrid transgene-containing portions of the rat GnRH promoter. In contrast, EGF, TGF-alpha, and IGF-I inhibited cell proliferation, while having subtle effects on neurite outgrowth. Thus, GT1-1 cells appear to be differentially responsive to distinct neurotrophic factors, providing a model for studying the specific effects of neurotrophic factors on functional differentiation, migration, and connectivity of hypothalamic neurons.
Thomas Harris, En el mismo río (Antología personal). Santiago, Ediciones Universidad Diego Portales, 2017, 195 pp. ISBN 978-956-314-383-6.
AleJAndrA ochoAUniversidad Diego Portales, Santiago, Chile alejandra.ochoa@udp.cl l a obra poética De Thomas Harris (La Serena, 1956) es considerada parte fundamental de nuestro canon literario. Perteneciente a la generación de los 80, la crítica ha valorado el lenguaje innovador que porta su primera poesía, la configuración de un sujeto que contempla el fin de la modernidad, la presencia de vastas conexiones intertextuales, la importancia del espacio urbano, entre otros rasgos distintivos de su ya extensa trayectoria escritural 1 .A treinta y dos años de su primera publicación, aparece En el mismo río (Antología personal), cuya selección fue hecha por el propio autor y que abarca desde Zonas de peligro (1985) hasta La batalla del Ebr(i)o (2014). Una producción poética que, de acuerdo a lo que señala el antologador en su "Introito", tiene unidad de sentido: "Por eso el título de esta antología: En el mismo río; porque pueden cambiar las tecnologías, la episteme de construir un texto, pero no el proyecto, ese SER que te hace el mismo, aunque nunca te bañes en el mismo río" (8). Asumiendo esta continuidad de sentido, ¿qué del mismo río se puede rastrear en esta selección de autor? Se proponen tres ejes temáticos que permitirían entender tanto el conjunto de su obra como la particularidad de esta antología.
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