Mutations in multiple genes of the growth hormone/IGF‐I axis have been identified in syndromes marked by growth failure. However, no pathogenic human mutations have been reported in the six high‐affinity IGF‐binding proteins (IGFBPs) or their regulators, such as the metalloproteinase pregnancy‐associated plasma protein A2 (PAPP‐A2) that is hypothesized to increase IGF‐I bioactivity by specific proteolytic cleavage of IGFBP‐3 and ‐5. Multiple members of two unrelated families presented with progressive growth failure, moderate microcephaly, thin long bones, mildly decreased bone density and elevated circulating total IGF‐I, IGFBP‐3, and ‐5, acid labile subunit, and IGF‐II concentrations. Two different homozygous mutations in PAPPA2, p.D643fs25* and p.Ala1033Val, were associated with this novel syndrome of growth failure. In vitro analysis of IGFBP cleavage demonstrated that both mutations cause a complete absence of PAPP‐A2 proteolytic activity. Size‐exclusion chromatography showed a significant increase in IGF‐I bound in its ternary complex. Free IGF‐I concentrations were decreased. These patients provide important insights into the regulation of longitudinal growth in humans, documenting the critical role of PAPP‐A2 in releasing IGF‐I from its BPs.

En el presente artículo se defiende la idea de que los sistemas externos de representación (como la escritura, el sistema numérico o los mapas) constituyen un dominio de conocimiento propio, bien diferenciado de las representaciones internas, objeto de estudio clásico de la psicología. El análisis de las características propias de estos sistemas externos de representación así como la revisión de las principales pautas de su adquisición permiten justificar la tesis defendida.

Several decades of research on conceptual change, from both developmental and instructional approaches, lead us to assume that this change should not be conceived as the progressive replacement of poor forms of knowledge by more powerful ones. Recent studies have shown that in order to understand this change in conceptual knowledge, we must know how multiple representations about the same domain, or even the same task, can coexist in interpersonal as well as intrapersonal analyses. This paper studies the acquisition and development of conceptual knowledge in terms of representational changes. Based on implicit theories that people use to interpret their social and natural world, it analyses the relationships between episodic and semantic knowledge in these implicit representations. We suggest that representational change can be understood through four related dimensions: (a) the transition from realism to epistemological perspectivism; (b) the hierarchical or heterogeneous nature of representational change; (c) the consistency and coherence of these representations; and (d) the role of specific-domain codes and languages in the representation of knowledge. Finally, we consider that research into this representational variability also requires diverse yet convergent methodological approaches.

Objective: To determine the influence of gestational age and fetal growth restriction on the cord blood adipokine profile, IGF1, and ghrelin levels, and their relationship with glucose metabolism. Study design: One hundred and ninety newborns (99 preterm and 91 full term) were studied and, according to their anthropometry at birth, classified as small (SGA) or adequate for gestational age (AGA). Methods: Venous cord blood serum levels of IGF1, IGF binding protein 3 (IGFBP-3), adiponectin, resistin, leptin, soluble leptin receptor (sOB-R), tumoral necrosis factor-a, interleukin 6 (IL-6), total ghrelin, and acylated ghrelin were determined and compared between preterm and full-term, as well as between SGA and AGA, newborns. Correlations with newborn weight, gestational age, and homeostatic model assessment (HOMA) index, as an index of insulin resistance, were determined. Results: Preterm newborns had higher HOMA, sOB-R, resistin, and IL-6 and lower IGF1, IGFBP-3, leptin, and adiponectin levels than full-term newborns. SGA had lower IGF1, IGFBP-3, leptin, IL-6, and adiponectin and higher sOB-R and total ghrelin than AGA newborns. Adiponectin and HOMA showed independent positive and negative correlations with gestational age respectively, but not with neonatal weight. Birth weight was correlated positively with IGF1 and leptin levels and negatively with total ghrelin ones. Conclusions: Our findings suggest that the lack of proper acquisition of adipose tissue by the fetus either due to prematurity or to fetal growth restriction is associated with changes in the cord blood adipokine profile that may contribute to the impairment of glucose metabolism.

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Mauri (2010). Se propone enmarcar esta relación dentro de un problema más general de la psicología: las relaciones entre cognición y acción. Se argumenta asimismo la importancia de definir la naturaleza representacional desde la que se postulan estas relaciones sobre todo en lo relativo al carácter implícito-explícito de las mismas, por su importancia teórica y por sus repercusiones para la intervención en la formación docente. La explicitación -vía para pasar del conocimiento práctico a la teoría-debe completarse con un proceso de implicitación o naturalización de los conocimientos teóricos construidos a través de la reflexión. Palabras clave: Teoría y práctica, cognición y acción, conocimiento implícito, teorías implícita, formación docente.

General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. We propose that the promoter mutation alters tissue-specific chromatin loop formation with consequent organ-specific deficiency of PMM2 leading to the restricted phenotype of HIPKD. Our findings extend the spectrum of genetic 5 causes for both HI and PKD and provide insights into gene regulation and PMM2 pleiotropy.6

Esta es la versión de autor del artículo publicado en: This is an author produced version of a paper published in:Cultura y Educación 20.1 (2008)