Association between inflammatory mediators and response to inhaled nitric oxide in a model of endotoxin-induced lung injury

INTRODUCTION: Inhaled nitric oxide (INO) allows selective pulmonary vasodilation in acute respiratory distress syndrome and improves PaO2 by redistribution of pulmonary blood flow towards better ventilated parenchyma. One-third of patients are nonresponders to INO, however, and it is difficult to predict who will respond. The aim of the present study was to identify, within a panel of inflammatory mediators released during endotoxin-induced lung injury, specific mediators that are associated with a PaO2 response to INO. METHODS: After animal ethics committee approval, pigs were anesthetized and exposed to 2 hours of endotoxin infusion. Levels of cytokines, prostanoid, leucotriene and endothelin-1 (ET-1) were sampled prior to endotoxin exposure and hourly thereafter. All animals were exposed to 40 ppm INO: 28 animals were exposed at either 4 hours or 6 hours and a subgroup of nine animals was exposed both at 4 hours and 6 hours after onset of endotoxin infusion. RESULTS: Based on the response to INO, the animals were retrospectively placed into a responder group (increase in PaO2 > or = 20%) or a nonresponder group. All mediators increased with endotoxin infusion although no significant differences were seen between responders and nonresponders. There was a mean difference in ET-1, however, with lower levels in the nonresponder group than in the responder group, 0.1 pg/ml versus 3.0 pg/ml. Moreover, five animals in the group exposed twice to INO switched from responder to nonresponder and had decreased ET-1 levels (3.0 (2.5 to 7.5) pg/ml versus 0.1 (0.1 to 2.1) pg/ml, P < 0.05). The pulmonary artery pressure and ET-1 level were higher in future responders to INO. CONCLUSIONS: ET-1 may therefore be involved in mediating the response to INO

Precipitation as the main driver of Neoglacial fluctuations of Gualas glacier, Northern Patagonian Icefield

© The Author(s), 2012. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Climate of the Past 8 (2012): 519-534, doi:10.5194/cp-8-519-2012.Glaciers are frequently used as indicators of climate change. However, the link between past glacier fluctuations and climate variability is still highly debated. Here, we investigate the mid- to late-Holocene fluctuations of Gualas Glacier, one of the northernmost outlet glaciers of the Northern Patagonian Icefield, using a multi-proxy sedimentological and geochemical analysis of a 15 m long fjord sediment core from Golfo Elefantes, Chile, and historical documents from early Spanish explorers. Our results show that the core can be sub-divided into three main lithological units that were deposited under very different hydrodynamic conditions. Between 5400 and 4180 cal yr BP and after 750 cal yr BP, sedimentation in Golfo Elefantes was characterized by the rapid deposition of fine silt, most likely transported by fluvio-glacial processes. By contrast, the sediment deposited between 4130 and 850 cal yr BP is composed of poorly sorted sand that is free of shells. This interval is particularly marked by high magnetic susceptibility values and Zr concentrations, and likely reflects a major advance of Gualas glacier towards Golfo Elefantes during the Neoglaciation. Several thin silt layers observed in the upper part of the core are interpreted as secondary fluctuations of Gualas glacier during the Little Ice Age, in agreement with historical and dendrochronological data. Our interpretation of the Golfo Elefantes glaciomarine sediment record in terms of fluctuations of Gualas glacier is in excellent agreement with the glacier chronology proposed for the Southern Patagonian Icefield, which is based on terrestrial (moraine) deposits. By comparing our results with independent proxy records of precipitation and sea surface temperature, we suggest that the fluctuations of Gualas glacier during the last 5400 yr were mainly driven by changes in precipitation in the North Patagonian Andes.This research was supported by an EU FP6 Marie Curie Outgoing Fellowship to S.B. Cruise NBP0505 was funded by the US National Science Foundation, Office of Polar Programs grant number NSF/OPP 03-38137 to J. Anderson (Rice University) and J. Smith Wellner (University of Houston). The Cimar-7 Program was supported by the Chilean National Oceanographic Committee (CONA, Grant C7F 01-10 to S. Pantoja)

Late Holocene current patterns in the northern Patagonian fjords recorded by sediment drifts in Aysén Fjord

Present-day circulation patterns in the southeastern Pacific Ocean are driven by the Antarctic Circumpolar Current, directing subantarctic surface water into the Patagonian fjords since at least the early Holocene. In this way, bottom current patterns in the area are regulated by the regional climate, although the complex bathymetry of the fjords has a significant impact as well. To understand the potential interplay of climate, seafloor topography and circulation patterns, we study the sedimentary infill of Aysén Fjord (~45°S) and reveal the first active sediment drifts in the region. These allow constraining the present-day circulation patterns in northern Patagonia and show an incoming (southward) as well as returning (northward) flow direction. While the general sedimentary evolution of the fjord (and thus also the sediment drifts) is climate-driven (i.e., it reflects variability in southern westerly wind strength), the onset of drift formation at ~3.7 ka does not seem to have originated from an abrupt change in regional climate. Instead, we propose that a megathrust earthquake described in paleoseismic records in the area could have resulted in subsidence of one (or more) of the many bathymetric highs in the Patagonian fjords, thus contributing to enhanced spilling of subantarctic water into the fjord. This study underscores the importance of multidisciplinary research to understand past and present bottom current circulation patterns and disentangle different possible feedback mechanisms

Contraintes psychologiques et organisationnelles

International audienc

A model of the Jovian internal field derived from in-situ and auroral constraints

peer reviewedThe internal magnetic field of Jupiter is known to be highly multi-polar, not only from the direct measurements performed by the Voyager and Pioneer probes but also from the unusually complex shape of the northern auroral oval. The limited amount of data obtained from the Voyager and Pioneer flybys do not permit accurate determination of the topology of the magnetic field, as they barely constrain, even the octupole contribution to the field. This does not allow one to reproduce the position of the auroras nor satisfactorily explain the shape and frequency range of the Jovian radio arcs. Successive attempts have been made to constrain the higher-order field using the position of the Io auroral footprint where the auroras are due to currents generated close to Io and carried along the magnetic field lines. Thus, the auroral spots should map to Io’s orbit. VIPAL, the latest model of this kind is a 5th order model. However, the VIPAL model was limited by three factors: the main constraints come from a unique L-Shell, the difficulty of mixing jovigraphic and magnetic data, and the non-linearity of the problem. These issues lead to numerically-demanding computations, with the scale of computation increasing as the square of the model order. We have developed a new method for computing the magnetic field using in-situ and auroral constraints (ISaAC) which we have applied to the computation of the Jovian magnetic field, based on Voyager, Pioneer, Galileo magnetic measurements and constrained by Io’s, Europa’s and Ganymede’s auroral footprint locations

ExPRES: an Exoplanetary and Planetary Radio Emissions Simulator

International audienceContext. Earth and outer planets are known to produce intense non-thermal radio emissions through a mechanism known as cyclotron maser instability (CMI), requiring the presence of accelerated electrons generally arising from magnetospheric current systems. In return, radio emissions are a good probe of these current systems and acceleration processes. The CMI generates highly anisotropic emissions and leads to important visibility effects, which have to be taken into account when interpreting the data. Several studies have shown that modelling the radio source anisotropic beaming pattern can reveal a wealth of physical information about the planetary or exoplanetary magnetospheres that produce these emissions. Aims. We present a numerical tool, called ExPRES (Exoplanetary and Planetary Radio Emission Simulator), which is able to reproduce the occurrence in a time-frequency plane of R−X CMI-generated radio emissions from planetary magnetospheres, exoplanets, or star-planet interacting systems. Special attention is given to the computation of the radio emission beaming at and near its source. Methods. We explain what physical information about the system can be drawn from such radio observations, and how it is obtained. This information may include the location and dynamics of the radio sources, the type of current system leading to electron acceleration and their energy, and, for exoplanetary systems, the orbital period of the emitting body and the strength, rotation period, tilt, and the offset of the planetary magnetic field. Most of these parameters can only be remotely measured via radio observations. Results. The ExPRES code provides the proper framework of analysis and interpretation for past, current, and future observations of planetary radio emissions, as well as for future detection of radio emissions from exoplanetary systems (or magnetic, white dwarf-planet or white dwarf-brown dwarf systems). Our methodology can be easily adapted to simulate specific observations once effective detection is achieved

The Organizational Work Factors' Effect on Mental Health Among Hospital Workers Is Mediated by Perceived Effort-Reward Imbalance. Result of a Longitudinal Study.

International audienceObjectives: This longitudinal study aimed to test the hypothesis that organizational work factors (OWFs) may be related to depressive symptoms through an increased effort-reward imbalance (ERI) ratio among registered nurses (RNs) and nursing assistants working in hospitals. Methods:We studied 2117 female RNs and nursing assistants who stayed in the same work unit and position during the follow-up from the ORSOSA (ORganisation des SOins-SAnt'e) longitudinal study. The work characteristics and workers' health were assessed in 2006 and 2008. Results: We confirmed our hypothesis of both direct and mediated effects of OWFs on workers' health. We showed that issues about patient-related information exchanges increased RNs' depressive disorders by increasing first a perceived ERI. Conclusions: Our results advocate integrating both the work organizational level and the individual level into preventive actions to improve workers' mental health

Auroral Processes at the Giant Planets: Energy Deposition, Emission Mechanisms, Morphology and Spectra

International audienceThe ionospheric response to auroral precipitation at the giant planets is reviewed, using models and observations. The emission processes for aurorae at radio, infrared, visible, ultraviolet, and X-ray wavelengths are described, and exemplified using ground- and space-based observations. Comparisons between the emissions at different wavelengths are made, where possible, and interpreted in terms of precipitating particle characteristics or atmospheric conditions. Finally, the spatial distributions and dynamics of the various components of the aurorae (moon footprints, low-latitude, main oval, polar) are related to magnetospheric processes and boundaries, using theory, in situ, and remote observations, with the aim of distinguishing between those related to internally-driven dynamics, and those related to the solar wind interaction