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OBJECTIVES: External skeletal robustness has been decreasing in children, potentially due to a lack of physical activity and the increased prevalence of obesity. However, whether socioeconomic status (SES) influences external skeletal robustness in adolescents has not yet been examined. METHODS: A cross-sectional study was performed to examine 370 Chilean adolescents (16.15 ± 1.01 years old) recruited from distinct educational establishments. Body fat percentage (BF%) was evaluated using Ellis' equations for Hispanic children. Obesity was defined as ≥25 BF% in males and ≥ 30 BF% in females. External skeletal robustness was obtained by measuring the humerus biepicondylar width and height (Frame-Index). SES was obtained through the ESOMAR survey. RESULTS: Females exhibited significantly greater BF% and lower Frame-Index values than males (P < .001). Obese adolescents (by BF%) had greater Frame-Index values than non-obese adolescents (P < .001). Females of medium-high SES had significantly lower BF% and Frame-Index values than females of medium and medium-low SES. BF% had a positive correlation with Frame-Index values in all SES groups studied, except in males of medium-high SES. As SES decreased, the correlation increased in both sexes, but overall, the correlation was greater in females than males. CONCLUSIONS: The results of this investigation suggest that obesity increases external skeletal robustness in adolescents. Additionally, lower SES corresponded to higher BF% and Frame-Index values. Therefore, modern conditions that influence the prevalence of obesity in adolescence could be affecting bone health in adolescents, primarily in females of medium-low SES.

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Los hallazgos osteológicos se intensi!caron en los últimos años. Se demostró que el esqueleto se comporta, además de sus funciones clásicas, como un órgano de secreción endocrina que sintetiza al menos dos hormonas: el factor de crecimiento de !broblastos 23 (FGF-23) y la osteocalcina (Ocn). La Ocn es un péptido pequeño que contiene 3 residuos de ácido glutámico. Estos residuos se carboxilan postraduccionalmente, quedando retenida en la matriz ósea. La forma decarboxilada en el primer residuo de ácido glutámico (GluOcn) fue reportada por poseer efectos biológicos; la resorción ósea es el mecanismo clave para su bioactivación. La presente revisión se centra en los conocimientos actuales sobre la función hormonal de la Ocn. A la fecha se reporta que la Ocn regularía el metabolismo energético aumentando la proliferación de células ` pancreáticas, y la secreción de insulina y de adiponectina. Sobre el músculo esquelético actuaría favoreciendo la absorción y el catabolismo de nutrientes. La función reproductiva masculina estaría regulada mediante el estímulo a las células de Leydig para sintetizar testosterona; en el desarrollo cerebral y la cognición, la Ocn aumentaría la síntesis de neurotransmisores monoaminados y disminuiría el neurotransmisor inhibidor GABA. Si bien son indispensables mayores evidencias para dilucidar los mecanismos reguladores por medio de los cuales actuaría la Ocn, los resultados enumerados en los distintos estudios experimentales establecen la importancia de este novedoso integrante molecular. Dilucidar su rol dentro de estos procesos interrelacionados en seres humanos abriría la posibilidad de utilizar a la Ocn en el tratamiento de enfermedades endocrino-metabólicas. (AU)

Osteological !ndings have intensi!ed in recent years. The skeleton behaves as an endocrine secretion organ that synthesizes at least two hormones: osteocalcin (Ocn) and !broblast growth factor 23 (FGF-23). Ocn is a small peptide that contains 3 glutamic acid residues. After translation, these residues are carboxylated to make possible its retention into the bone matrix. Decarboxylation on the !rst glutamic acid residue (GluOcn) has been reported to have biological effects. Bone resorption is the key mechanism for its bioactivation. This review focuses on current knowledge on Ocn hormonal function. It has been reported that Ocn regulates energy metabolism by increasing the proliferation of pancreatic ` cells, and the secretion of insulin and adiponectin. On the skeletal muscle, it may act by favoring the absorption and catabolism of nutrients. Male reproductive function might be regulated by stimulating Leydig cells to synthesize testosterone. Regarding brain development and cognition, Ocn would increase monoamine neurotransmitters synthesis and decrease inhibitory neurotransmitter GABA. Although more evidence is needed to elucidate the regulatory mechanisms of Ocn, different experimental studies establish the importance of this novel molecular mediator. Clarifying its role within interrelated processes in humans, might open the possibility of using Ocn in different treatments of endocrine-metabolic diseases. (AU)

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El esqueleto es uno de los sistemas más grandes de un vertebrado y, como tal, es razonable especular que no puede funcionar aislado del resto del organismo. De hecho, sabemos que existen sistemas complejos de regulación cruzada entre el esqueleto y muchos otros órganos. Hoy poseemos herramientas que nos permiten realizar supresión genética en células o tejidos específicos. Esto nos ha permitido comprender cómo los órganos se comunican entre sí y ha revitalizado el concepto de fisiología del organismo como un todo. Efectivamente, los últimos años han sido testigos del descubrimiento de funciones inesperadas que ejerce el esqueleto y que afectan al organismo en su totalidad. Una de tales funciones reconocidas recientemente es el control del metabolismo energético, a través de la secreción de osteocalcina. La osteocalcina es una hormona producida por los osteoblastos que regula la secreción de insulina, la sensibilidad a esta hormona y el metabolismo energético. Los hallazgos iniciales suscitaron varias preguntas fundamentales sobre la naturaleza de la acción de la insulina sobre el hueso. Pero esto solo fue la punta del iceberg. Efectivamente, más adelante se descubrió, mediante el análisis de ratones que carecen del receptor de insulina (Ins R) solamente en osteoblastos, que la acción de la insulina sobre estas células favorecía la homeostasis de la glucosa en todo el cuerpo. Es importante destacar que esta función de la insulina en los osteoblastos opera mediante la regulación negativa de la carboxilación y la biodisponibilidad de la osteocalcina. Más aún, se observó que las vías de señalización de la insulina en los osteoblastos regulan positivamente no solo la formación sino también la resorción del hueso. Curiosamente, parece que las vías de señalización de la insulina en osteoblastos pueden inducir la activación de la osteocalcina mediante la estimulación de la actividad de los osteoclastos. De hecho, el bajo pH generado durante la resorción ósea es suficiente para desencadenar la descarboxilación (y subsiguiente activación) de la osteocalcina. En breve discutiremos dos nuevas proposiciones: 1) los osteoblastos son un blanco utilizado por la insulina para controlar la homeostasis de la glucosa en todo el organismo y 2) la resorción ósea desempeña un papel fundamental en la regulación de la activación de la osteocalcina. (AU)

The skeleton is one of the biggest systems in a vertebrate animal and, as such, it is reasonable to speculate that it cannot function isolated from the rest of the organism. In fact, we know that complex systems exist for the cross-regulation between the skeleton and several other organs. Today, we have the tools that allow us to perform genetic suppression in specific cells or tissues. This has allow us understand the mechanisms by which the organs communicate with each other and has revitalized the concept of organismal physiology as a whole. Studies conducted in recent years have uncovered unexpected functions performed by the skeleton. One of these is the control of global energy metabolism, through the secretion of osteocalcin, a protein produced by osteoblasts that acts as a hormone regulating insulin secretion, insulin sensitivity and energy expenditure. The evidence comes from the analysis of mice lacking insulin receptor (InsR) exclusively in osteoblasts. These mice have a global metabolic phenotype demonstrating that the action of insulin in osteoblasts promotes the homeostasis of glucose throughout the body. This action of insulin in osteoblasts is mediated by the negative regulation of the carboxylation (and bioavailability) of osteocalcin. The decarboxylation (and activation) of osteocalcin, in turn, occurs in the osteoclastic resorption pit. Briefly: the osteoblast is a target used by insulin to control the homeostasis of glucose throughout the body and bone resorption is the mechanism that regulates the activation of osteocalcin. (AU)

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Sigmodontinae rodents constitute the second-largest subfamily among mammals. Alongside the taxonomic diversity, they are also ecologically diverse, exhibiting a wide array of locomotion modes, with semifossorial, terrestrial, semiaquatic, scansorial, arboreal, and saltatorial forms. To understand the ecomorphologic aspects that allow these rodents to display such locomotion diversity, we analyzed 35 qualitative characters of the appendicular skeleton (humerus, ulna, radius, scapula, femur, tibia, ilium, ischium and pubis) in 795 specimens belonging to 64 species, 34 genera and 10 tribes, representing all locomotion modes assigned to this subfamily. We performed a statistical analysis based upon the coefficient of trait differentiation to test the congruence of character states and the different locomotion modes. We also mapped characters states in a molecular phylogeny in order to reconstruct ancestral states and to evaluate how appendicular characters evolved within main lineages of Sigmodontinae radiation under a phylogenetic framework. The statistical analyses revealed six characters related to specific locomotion modes, except terrestrial. The mapping and parsimony ancestral states reconstruction identified two characters with phylogenetical signal and eight characters that are exclusively or more frequently recorded in certain modes of locomotion, four of them also detected by the statistical analysis. Notwithstanding the documented morphological variation, few changes characterize the transition to each of the locomotion modes, at least regarding the appendicular skeleton. This finding corroborates previous results that showed that sigmodontines exhibit an all-purpose appendicular morphology that allows them to use and explore a great variety of habitats.

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Anurans exhibit a particularly wide range of locomotor modes that result in wide variations in their skeletal structure. This article investigates the possible correlation between morphological aspects of the hylid postcranial skeleton and their different locomotor modes and habitat use. To do so, we analyzed 18 morphometric postcranial variables in 19 different anuran species representative of a variety of locomotor modes (jumper, hopper, walker, and swimmer) and habitat uses (arboreal, bush, terrestrial, and aquatic). Our results show that the evolution of the postcranial hylid skeleton cannot be explained by one single model, as for example, the girdles suggest modular evolution while the vertebral column suggests other evolutionary modules. In conjunction with data from several other studies, we were able to show a relationship between hylid morphology and habitat use; offering further evidence that the jumper/swimmer and walker/hopper locomotor modes exhibit quite similar morphological architecture. This allowed us to infer that new locomotor modalities are, in fact, generated along a morphological continuum. J. Morphol. 278:403-417, 2017. © 2017 Wiley Periodicals, Inc.

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The contribution of chronological age, skeletal age (Fels method) and body size to variance in peak velocity derived from the Carminatti Test was examined in 3 competitive age groups of Brazilian male soccer players: 10-11 years (U-12, n=15), 12-13 years (U-14, n=54) and 14-15 years (U-16, n=23). Body size and soccer-specific aerobic fitness were measured. Body composition was predicted from skinfolds. Analysis of variance and covariance (controlling for chronological age) were used to compare soccer players by age group and by skeletal maturity status within of each age group, respectively. Relative skeletal age (skeletal age minus chronological age), body size, estimated fat-free mass and performance on the Carminatti Test increased significantly with age. Carminatti Test performance did not differ among players of contrasting skeletal maturity status in the 3 age groups. Results of multiple linear regressions indicated fat mass (negative) and chronological age (positive) were significant predictors of peak velocity derived from the Carminatti Test, whereas skeletal age was not a significant predictor. In conclusion, the Carminatti Test appears to be a potentially interesting field protocol to assess intermittent endurance running capacity in youth soccer programs since it is independent of biological maturity status.

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