Fluctuations in export productivity over the last century from sediments of a southern Chilean fjord (44°S)

Author Posting. © The Authors, 2005. This is the author's version of the work. It is posted here by permission of Elsevier B. V. for personal use, not for redistribution. The definitive version was published in Estuarine, Coastal and Shelf Science 65 (2005): 587-600, doi:10.1016/j.ecss.2005.07.005.Here we present the first reconstruction of changes in surface primary production during the last century from the Puyuhuapi fjord in southern Chile, using a variety of parameters (diatoms, biogenic silica, total organic carbon, chlorins, and proteins) as productivity proxies. Two sediment cores from the head and the center of the fjord were analyzed and compared to gain insights on past changes in productivity in these two different depositional environments. Higher sedimentation rates found at the head of the fjord result from the combination of a shallower water column and a restricted circulation by the occurrence of a sill. Additionally, sediment mixing depths estimated from 210Pb data suggest that suboxic conditions may dominate the bottom water and the sediment-water interface in this location. Productivity of the Puyuhuapi fjord during the last century was characterized by a constant increase from the late 19th century to the early 1980s, then decreased until the late-1990s, and then rose again to present-day values. The influence of rainfall on productivity was most noticeable during periods of low rainfall, which coincided with decreased overall productivity within the Puyuhuapi fjord. Simultaneous variations in productivity and rainfall in the study area suggest that marine productivity could respond to atmospheric-oceanic interactions at a local scale. At a regional scale, marine productivity of the area may be related to other large-scale processes such as the El Niño Southern Oscillation.We are grateful to the Ministerio de Hacienda de Chile (Chilean Ministry of Treasury) and the National Oceanographic Committee (CONA) for financial support to carry out the Cimar-7 Fiordo Program (Grant C7F 01-10 to Silvio Pantoja), the FONDAP-COPAS Center, and Grant 200.031.085-1 (UdeC) for financial support. Sepúlveda was funded by a scholarship from the Graduate School of the University of Concepción and by the FONDAP-COPAS Center. Additional support was given by Fundación Andes through the Woods Hole Oceanographic Institution/University of Concepción agreement

The modular systems biology approach to investigate the control of apoptosis in Alzheimer's disease neurodegeneration

Apoptosis is a programmed cell death that plays a critical role during the development of the nervous system and in many chronic neurodegenerative diseases, including Alzheimer's disease (AD). This pathology, characterized by a progressive degeneration of cholinergic function resulting in a remarkable cognitive decline, is the most common form of dementia with high social and economic impact. Current therapies of AD are only symptomatic, therefore the need to elucidate the mechanisms underlying the onset and progression of the disease is surely needed in order to develop effective pharmacological therapies. Because of its pivotal role in neuronal cell death, apoptosis has been considered one of the most appealing therapeutic targets, however, due to the complexity of the molecular mechanisms involving the various triggering events and the many signaling cascades leading to cell death, a comprehensive understanding of this process is still lacking. Modular systems biology is a very effective strategy in organizing information about complex biological processes and deriving modular and mathematical models that greatly simplify the identification of key steps of a given process. This review aims at describing the main steps underlying the strategy of modular systems biology and briefly summarizes how this approach has been successfully applied for cell cycle studies. Moreover, after giving an overview of the many molecular mechanisms underlying apoptosis in AD, we present both a modular and a molecular model of neuronal apoptosis that suggest new insights on neuroprotection for this disease

Modelación numérica de un evento de viento Raco en Chile central y su sensibilidad a la topografía

Tesis para optar al grado de Magíster en Meteorología y ClimatologíaEn la precordillera de Chile central y particularmente en el cajón Maipo se observan flujos forzados por el terreno, los cuales reciben el nombre de viento Raco. Corresponde a un flujo que desciende, se calienta y sale por el cajón cordillerano. Se produce principalmente durante las noches de invierno. El objetivo del estudio es explorar los factores topográficos que inciden en el Raco. Para esto, se realizan simulaciones numéricas con el modelo WRF para un caso de estudio entre el 16 y 26 de junio del 2002. Posterior a esto, se realiza una serie de simulaciones que modifican la topografía. Para el experimento de control, se verifica que el modelo reproduce características similares a las observadas en superficie, y en altura se observa un chorro del este que se maximiza en 1400 metros de altitud aproximadamente. En los experimentos de topografía modificada se observa que la intensidad del chorro depende principalmente de la interacción del viento con la zona noreste del valle. En algunos casos el chorro de altura penetra hasta la superficie, pero sólo hasta la salida del valle (La Obra). Aquí el flujo experimenta un despegue, el cual puede deberse a efectos dinámicos como un salto hidráulico, o a una convergencia entre el aire cálido que desciende y el aire frío de la cuenca de Santiago. Para los vientos en superficie se observa que la topografía local es de gran relevancia en el desarrollo del Raco, el cual se intensifica o debilita dependiendo de cambios en cerro Purgatorio

Galectin-3 levels in patients hospitalized for decompensated heart failure Galectina-3: Experiencia en pacientes Chilenos con diagnóstico de insuficiencia cardíaca descompensada

© 2017, Sociedad Medica de Santiago. All rights reserved. Background: Galectin-3 (Gal-3) is a mediator of myocardial fibrosis involved in cardiac remodeling and a potential new prognosis marker in heart failure (HF). Aim: To measure Gal-3 at the moment of discharge in patients hospitalized for HF and its association with different variables. Material and Methods: Patients hospitalized for decompensated HF from four hospitals between August 2014 and March 2015, were included. Demographic, clinical and laboratory variables were recorded at the time of admission. At discharge, a blood sample was withdrawn to measure Gal-3 and brain natriuretic propeptide (Pro-BNP). Patients were separated in two groups, according to the level of Gal-3 (using a cutoff value of 17.8 ng/mL), comparing clinical and laboratory values between groups. Results: We included 52 patients with HF aged 70 ± 17 years (42% females). Functional capacity was III-IV in 46% of patients and the ejection fraction was 34.9 ±