Pseudoartrosis congénita bilateral de la clavícula: a propósito de un caso familiar

Presentamos una paciente de nueve meses con pseudoartrosis congénita bilateral de ambas clavículas, cuya madre presenta el mismo cuadro. Dicho cuadro es una entidad rara, pobremente documentada en la ortopedia pediátrica. La etiología y patogenia aún permanece oscura. La apariencia clínico-radiológica consiste en la ausencia desde el nacimiento de un defecto de unión a nivel del tercio medio clavicular característico. El diagnóstico diferencial debe hacerse con las fracturas perinatales, pseudoartrosis postraumáticas y disostosis cleido-craneales.The case of a female patient of nine months of are and her mother, 41-year-old showing a Congenital Bilateral Pseudoarthrosis of the clavicle are presented. This is a rare entity that has been poorly documented in paediatrics orthopedics literature. The etiology and pathogenesis still remain unclear. The clinical and radiological appearance are characteristic. Differential diagnosis lies between postpartum fractures, postraumatic pseudoarthrosis, and cleidocraneal dysostosis

Turnover time of fluorescent dissolved organic matter in the dark global ocean

Research articleMarine dissolved organic matter (DOM) is one of the largest reservoirs of reduced carbon on Earth. In the dark ocean (4200 m), most of this carbon is refractory DOM. This refractory DOM, largely produced during microbial mineralization of organic matter, includes humic-like substances generated in situ and detectable by fluorescence spectroscopy. Here we show two ubiquitous humic-like fluorophores with turnover times of 435±41 and 610±55 years, which persist significantly longer than the B350 years that the dark global ocean takes to renew. In parallel, decay of a tyrosine-like fluorophore with a turnover time of 379±103 years is also detected. We propose the use of DOM fluorescence to study the cycling of resistant DOM that is preserved at centennial timescales and could represent a mechanism of carbon sequestration (humic-like fraction) and the decaying DOM injected into the dark global ocean, where it decreases at centennial timescales (tyrosine-like fraction).Versión del editor10,015

Bases moleculares de la selectividad de ligandos por receptores de melatonina

La hormona melatonina (MT), o N-acetil-5-metoxitriptamina, secretada por la glándula pineal, es responsable de la regulación del sueño y el ritmo circadiano a través de la modulación del núcleo supraquiasmático, entre otras funciones. MT actúa sobre 2 receptores diferentes, MT1 (o MT1A) y MT2 (o MT1B), que funcionan acoplados a proteínas G (GPCR). La propia melatonina y otros agonistas de los receptores MT pueden ser usadas para marcar los ritmos circadianos, facilitar el sueño o ejercer un efecto en los osciladores periféricos. Por otro lado, los antagonistas de estos receptores se pueden utilizar para mejorar nuestra comprensión del papel de la MT en el organismo. Sin embargo, los trabajos de diseño molecular basados en la estructura se ven obstaculizados por la ausencia de un modelo tridimensional (3D) experimental de los receptores MT1 o MT2. Los modelos construidos por técnicas de homología ayudan pero tanto el modo real de unión como el mecanismo de activación del receptor siguen estando definidos de forma imprecisa. En este trabajo, hemos utilizado las estructuras 3D recientemente publicadas de los receptores humanos 5-HT1B and 5-HT2B de serotonina (5HT) para construir modelos 3D de los receptores MT1 y MT2 humanos que sirven para explicar una serie de resultados experimentales, incluyendo los provenientes de estudios de mutagénesis dirigida y de selectividad de unión al receptor MT2 de una serie de ligandos sintéticos publicados en la literatura. Nuestros modelos también explican la conservación evolutiva de ciertos aminoácidos clave en toda la familia de receptores MT y destacan las regiones del bolsillo de unión que pueden ser explotadas para conseguir perfiles distintos de selectividad entre los receptores de MT y 5H

Bases moleculares de la selectividad de ligandos por receptores de melatonina

La hormona melatonina (MT), o N-acetil-5-metoxitriptamina, secretada por la glándula pineal, es responsable de la regulación del sueño y el ritmo circadiano a través de la modulación del núcleo supraquiasmático, entre otras funciones. MT actúa sobre 2 receptores diferentes, MT1 (o MT1A) y MT2 (o MT1B), que funcionan acoplados a proteínas G (GPCR). La propia melatonina y otros agonistas de los receptores MT pueden ser usadas para marcar los ritmos circadianos, facilitar el sueño o ejercer un efecto en los osciladores periféricos. Por otro lado, los antagonistas de estos receptores se pueden utilizar para mejorar nuestra comprensión del papel de la MT en el organismo. Sin embargo, los trabajos de diseño molecular basados en la estructura se ven obstaculizados por la ausencia de un modelo tridimensional (3D) experimental de los receptores MT1 o MT2. Los modelos construidos por técnicas de homología ayudan pero tanto el modo real de unión como el mecanismo de activación del receptor siguen estando definidos de forma imprecisa. En este trabajo, hemos utilizado las estructuras 3D recientemente publicadas de los receptores humanos 5-HT1B and 5-HT2B de serotonina (5HT) para construir modelos 3D de los receptores MT1 y MT2 humanos que sirven para explicar una serie de resultados experimentales, incluyendo los provenientes de estudios de mutagénesis dirigida y de selectividad de unión al receptor MT2 de una serie de ligandos sintéticos publicados en la literatura. Nuestros modelos también explican la conservación evolutiva de ciertos aminoácidos clave en toda la familia de receptores MT y destacan las regiones del bolsillo de unión que pueden ser explotadas para conseguir perfiles distintos de selectividad entre los receptores de MT y 5H

Water mass age and ageing driving chromophoric dissolved organic matter in the dark global ocean

Research articleThe omnipresence of chromophoric dissolved organic matter (CDOM) in the open ocean enables its use as a tracer for biochemical processes throughout the global overturning circulation. We made an inventory of CDOM optical properties, ideal water age (τ), and apparent oxygen utilization (AOU) along the Atlantic, Indian, and Pacific Ocean waters sampled during the Malaspina 2010 expedition. A water mass analysis was applied to obtain intrinsic, hereinafter archetypal, values of τ, AOU, oxygen utilization rate (OUR), and CDOM absorption coefficients, spectral slopes and quantum yield for each one of the 22 water types intercepted during this circumnavigation. Archetypal values of AOU and OUR have been used to trace the differential influence of water mass aging and aging rates, respectively, on CDOM variables. Whereas the absorption coefficient at 325nm (a325) and the fluorescence quantum yield at 340nm (Φ340) increased, the spectral slope over the wavelength range 275–295nm (S275–295) and the ratio of spectral slopes over the ranges 275–295nm and 350–400nm (SR) decreased significantly with water mass aging (AOU). Combination of the slope of the linear regression between archetypal AOU and a325 with the estimated global OUR allowed us to obtain a CDOM turnover time of 634 ± 120 years, which exceeds the flushing time of the dark ocean (>200 m) by 46%. This positive relationship supports the assumption of in situ production and accumulation of CDOM as a by-product of microbial metabolism as water masses turn older. Furthermore, our data evidence that global-scale CDOM quantity (a325) is more dependent on aging (AOU), whereas CDOM quality (S275–295, SR, Φ340) is more dependent on aging rate (OUR).Versión del editor4,785

Holocene climate variability, vegetation dynamics and fire regime in the central Pyrenees: the Basa de la Mora sequence (NE Spain)

High resolution multiproxy data (pollen, sedimentology, geochemistry, chironomids and charcoal) from the Basa de la Mora (BSM) lake sequence (42° 32′ N, 0° 19′ E, 1914 m a.s.l.) show marked climate variability in the central southern Pyrenees throughout the Holocene. A robust age model based on 15 AMS radiocarbon dates underpins the first precise reconstruction of rapid climate changes during the Holocene from this area. During the Early Holocene, increased winter snowpack and high snowmelt during summer, as a consequence of high seasonality, led to higher lake levels, a chironomid community dominated by non-lacustrine taxa (Orthocladiinae) related to higher inlet streams, and a forested landscape with intense run-off processes in the watershed. From 9.8 to 8.1 cal ka BP, climate instability is inferred from rapid and intense forest shifts and high fluctuation in surface run-off. Shifts among conifers and mesophytes reveal at least four short-lived dry events at 9.7, 9.3, 8.8 and 8.3 cal ka BP. Between 8.1 and 5.7 cal ka BP a stable climate with higher precipitation favoured highest lake levels and forest expansion, with spread of mesophytes, withdrawal of conifers and intensification of fires, coinciding with the Holocene Climate Optimum. At 5.7 cal ka BP a major change leading to drier conditions contributed to a regional decline in mesophytes, expansion of pines and junipers, and a significant lake level drop. Despite drier conditions, fire activity dropped as consequence of biomass reduction. Two arid intervals occurred between 2.9 and 2.4 cal ka BP and at 1.2–0.7 cal ka BP (800–1300 AD). The latter coincides with the Medieval Climate Anomaly and is one of the most arid phases of the Holocene in BSM sequence. Anthropogenic disturbances were small until 700 AD, when human pressure over landscape intensified, with Olea cultivation in the lowlands and significant deforestation in highlands. Colder and unfavourable weather conditions during the second part of the Little Ice Age caused a temporary cease of high-land management. The most intense anthropogenic disturbances occurred during the second half of 19th century. Last decades are characterized by recovery of the vegetation cover as a result of land abandonment, and lowered lake levels, probably due to higher temperatures

Landscape dynamics and fire activity since 6740 cal yr BP in the Cantabrian region (La Molina peat bog, Puente Viesgo, Spain)

A lack of paleobotanic studies with adequate resolution and multiproxy approaches has limited proper discussion of vegetation dynamics in Cantabria and of the role of fires in the configuration of the plant landscape during the Holocene in the northwest part of the Iberian peninsula. The pollen diagram of La Molina peat bog in Puente Viesgo (43 ‹15 Œ38 N.3 ‹58 Œ37 W; ETRS89), located at 484 m.a.s.l., and the study of its sedimentary charcoals allowed the acquisition of a continuous and thorough fire sequence for the last 6 700 cal yr BP and an understanding of its relationship to the forest. The results show the importance of human influence on the incidence and characteristics of fire activity during the different phases studied: the Neolithic, Bronze Age, Iron Age, Roman period, and Middle Ages. A synergy seems to exist between dry climate periods (especially during Bond events 3 and 4) and a greater presence of biomass. As the Holocene advances, vegetation coverage clearly tends to decrease. This study provides key elements for understanding the role of fire activity in the forest dynamics of deciduous and evergreen Quercus, Corylus, Pinus, Fagus, and Alnus and demonstrates the strongly artificialized character of the present landscape

Negative responses of highland pines to anthropogenic activities in inland Spain: a palaeoecological perspective

Palaeoecological evidence indicates that highland pines were dominant in extensive areas of the mountains of Central and Northern Iberia during the first half of the Holocene. However, following several millennia of anthropogenic pressure, their natural ranges are now severely reduced. Although pines have been frequently viewed as first-stage successional species responding positively to human disturbance, some recent palaeobotanical work has proposed fire disturbance and human deforestation as the main drivers of this vegetation turnover. To assess the strength of the evidence for this hypothesis and to identify other possible explanations for this scenario, we review the available information on past vegetation change in the mountains of northern inland Iberia. We have chosen data from several sites that offer good chronological control, including palynological records with microscopic charcoal data and sites with plant macro- and megafossil occurrence. We conclude that although the available long-term data are still fragmentary and that new methods are needed for a better understanding of the ecological history of Iberia, fire events and human activities (probably modulated by climate) have triggered the pine demise at different locations and different temporal scales. In addition, all palaeoxylological, palynological and charcoal results obtained so far are fully compatible with a rapid human-induced ecological change that could have caused a range contraction of highland pines in western Iberia