Persisting Mixed Cryoglobulinemia in Chikungunya Infection

Chikungunya virus is present in tropical Africa and Asia and is transmitted by mosquito bites. The disease is characterized by fever, headache, severe joint pain and transient skin rash for about a week. Most patients experience persisting joint pain and/or stiffness for months to years. In routine practice, diagnosis is based upon serology. Since 2004 there has been an ongoing giant outbreak of Chikungunya fever in East Africa, the Indian Ocean Islands, India and East Asia. In parallel, more than 1,000 travelers were diagnosed with imported Chikungunya infection in most developed countries. Considering the clinical features of our patients (joint pain), we hypothesized that cryoglobulins could be involved in the pathophysiology of the disease as observed in chronic hepatitis C infection. Cryoglobulins, which are immunoglobulins that precipitate when temperature is below 37°C, can induce rheumatic and vascular disorders. From April 2005 through May 2007, we screened all patients with possible imported Chikungunya infection for cryoglobulins. They were present in over 90% of patients, and possibly responsible for the unexpected false negativity of serological assays. Cryoglobulin frequency and levels decreased with time in recovering patients

Biophysical Interactions Control the Size and Abundance of Large Phytoplankton Chains at the Ushant Tidal Front

International audiencePhytoplankton blooms are usually dominated by chain-forming diatom species that can alter food pathways from primary producers to predators by reducing the interactions between intermediate trophic levels. The food-web modifications are determined by the length of the chains; however, the estimation is biased because traditional sampling strategies damage the chains and, therefore, change the phytoplankton size structure. Sedimentological studies around oceanic fronts have shown high concentrations of giant diatom mats (.1 cm in length), suggesting that the size of diatom chains is underestimated in the pelagic realm. Here, we investigate the variability in size and abundance of phytoplankton chains at the Ushant tidal front (NW France) using the Video Fluorescence Analyzer (VFA), a novel and non-invasive system. CTD and Scanfish profiling characterized a strong temperature and chlorophyll front, separating mixed coastal waters from the oceanic-stratified domain. In order to elucidate spring-neap variations in the front, vertical microstructure profiler was used to estimate the turbulence and vertical nitrate flux. Key findings were: (1) the VFA system recorded large diatom chains up to 10.7 mm in length; (2) chains were mainly distributed in the frontal region, with maximum values above the pycnocline in coincidence with the maximum chlorophyll; (3) the diapycnal fluxes of nitrate enabled the maintenance of the bloom in the frontal area throughout the spring-neap tidal cycle; (4) from spring to neap tide the chains length was significantly reduced; (5) during neap tide, the less intense vertical diffusion of nutrients, as well as the lower turbulence around the chains, intensified nutrient-depleted conditions and, thus, very large chains became disadvantageous. To explain this pattern, we suggest that size plasticity is an important ecological trait driving phytoplankton species competition. Although this plasticity behavior is well known from experiments in the laboratory, it has never been reported from observations in the field

Abundance of phytoplankton.

<p>The table shows the average abundance values (10³×cells L⁻¹± standard deviation) of chain-forming taxa in three delimited regions in the FroMVar transect.</p

Schematic representation of the Video Fluorescence Analyzer (VFA).

<p>Imaging system components (A), and cartoon of the mechanical design of the VFA (B).</p

Study location and delimitation of the oceanographic regions.

<p>Map of the study area off NE Atlantic region (A). Station position and hydrological typology at the Ushant tidal front: mixed, frontal, and stratified (B). nMDS plot based on hydrological data with superimposed cluster analysis at a Euclidean distance of 4.7 (–)(C). Each dotted circle represents a significant cluster (SIMPROF <i>P</i><0.05).</p

Snapshot of fluorescent particles imaged with the Video Fluorescence Analyzer (VFA).

<p>Example of images taken in the tidal front during neap (A, B) and spring tides (C, D). The most representative phytoplankton chains are shown in the panels. The shape and cell connection type of the longest phytoplankton chains (red arrows) suggest that they belong to <i>Pseudonitzschia</i> spp. (C, D).</p

Nutrients in the study area.

<p>Nitrate (A, B) and silicate concentrations along the transects (E, F). Mean size of the phytoplankton chains relative to depth and nitrate concentrations (C) and silicate (D). The panels located in the left and right refer to observations from spring and neap tide, respectively. Numbers along the top of the panels A, B, E, and F refer to sampling stations (Fig. 1). Italic bold numbers indicate stations located in the front. In panels C, D, G, and H, the mean size of chains at each sample are shown as proportional bubbles. Note that the stations with abundance lower than 5×10³ cells L⁻¹ were not added to the bubble plots. Vertical grey line = 13°C bottom thermocline.</p

Two-way ANOVA test.

<p>Results of the effect of tide (spring and neap) and region (mixed, frontal, and stratified) on the size and abundance of phytoplankton chains. Asterisks indicate significant effects (*<i>P</i><0.001).</p

La gestion d'un lagon en mutation : acteurs, enjeux et recherche-action en Nouvelle-Calédonie (Pacifique Sud)

Cet article synthétise les résultats d'un programme de recherche interdisciplinaire effectué sur la côte nord-ouest de la province Nord de la Nouvelle-Calédonie (Pacifique sud) de 2008 à 2011. Cette région fait face aux rapides changements urbains et économiques induits par la création d'un important complexe métallurgique. Ce projet industriel, porteur de développement économique, est aussi un projet politique emblématique du processus original de décolonisation négociée dans lequel la Nouvelle-Calédonie est engagée. Une démarche scientifique adaptative a été mise en place pour améliorer la connaissance de l'écosociosystème côtier et mieux gérer les usages littoraux, et les petites pêcheries en particulier. Cette démarche combinait trois approches complémentaires : recherche-action (s'appuyant sur les points de vue et les logiques des parties prenantes locales), interdisciplinarité (sciences biologiques, sociales et juridiques) et partenariat entre plusieurs institutions de recherche et de développement. Les résultats montrent que les principaux défis de gestion des usages littoraux sont fortement imbriqués et renvoient à des questions environnementales, sociales, culturelles aussi bien qu'économiques et politiques. Toutes les conditions pour la réussite d'une gestion participative ne sont pas actuellement réunies à l'échelle de la zone d'étude. Cependant, notre étude ouvre des pistes pour la promotion d'initiatives de gouvernance partagée, en se fondant sur des dynamiques locales existantes ou émergentes pouvant être élargies à d'autres échelles. Des orientations de politiques publiques sont aussi suggérées, incluant la promotion d'approches territoriales pour le développement local. (Résumé d'auteur