Éditeur(s) : HAL CCSD
Résumé : Red blood cell hemodynamics influence blood rheology and thus circulatory function. Different authors showed that red blood cells are heterogeneous in blood flow. This heterogeneity could be explained by physical characteristics such as morphology, aggregability and deformability, but also by cellular and molecular environment. All these notions are found in sickle cell disease where sickle red blood cells become more rigid, leading to vascular occlusions, increased with an inflammatory context. In a preceding study, our results showed that velocity heterogeneity allow RBC classification, leading to different RBC sub-groups, using a dynamical approach and flow studies. In order to have a better understanding of the physiological meaning of such an heterogeneity, dynamical velocity experiences have been conducted in the case of normal and sickle red blood cells with different endothelial activations by proinflammatory cytokines, under a constant venular flow. Thus, normal and sickle red blood cells are classified into different sub-groups, showing their heterogeneity. Moreover, sub-population velocities and distribution evolve differently according to vascular state or treatment. These results show that red blood cell velocities and rheology depend on vascular environment and red blood cell morphology. However, the physiological meaning of this behavior should be explained by cellular and molecular effects of such activation.
https://hal.archives-ouvertes.fr/hal-00201461

hal-00201461
https://hal.archives-ouvertes.fr/hal-00201461
https://hal.archives-ouvertes.fr/hal-00201461/document
https://hal.archives-ouvertes.fr/hal-00201461/file/RBCV_Marianne_v1.pdf

Éditeur(s) : Amer Geophysical Union
Résumé : Hydrographic (0-1000 dbar) and direct current measurements (0-600 dbar) along 165-degrees-E (20-degrees-S-10-degrees-N) between January 1984 and July 1991 are used to investigate the mean circulation and its relationships with the distributions of salinity and potential vorticity on isopycnal surfaces. Less well documented mean sections along 142-degrees-E and 137-degrees-E are used to complement the 165-degrees-E analysis. The Equatorial Undercurrent is centered on the equator at 165-degrees-E and on 0.5-degrees-N at 142-degrees-E. No variation in its transport (15.0 x 10(6) m3 s-1) is found between those longitudes. We find indication of the Equatorial Undercurrent at 137-degrees-E-0.75-degrees-N in the geostrophic field. The northern and southern Subsurface Countercurrents are clearly identified by extrema of eastward velocity at 165-degrees-E around 3-degrees-N and 3-degrees-S (250 dbar). No evidence of a southern Subsurface Countercurrent is found at 142-degrees-E. At 137-degrees-E the northern Subsurface Countercurrent is not characterized by a local extrema of eastward velocity: the North Equatorial Countercurrent seems to extend from the surface to 400 dbar with a southward shift of its core. Analysis of the seasonal variability at 165-degrees-E indicates that the Equatorial Undercurrent transport increases by a factor 2 between January (10.7 x 10(6) m3 s-1) and July (21.5 x 10(6) m3 s-1) and the Equatorial Intermediate Current transport is halved (6.3 x 10(6) m3 s-1 in January, 3.5 x 10(6) m3 s-1 in July). hi contrast, the transport of the Subsurface Countercurrents does not vary substantially between those two months. The meridional distributions of salinity and potential vorticity show that the axes of the main eastward currents are associated with strong meridional property gradients, not with property extrema. The eastward currents thus represent a barrier to the northward extension of the high salinity Tropical Water. Relatively weak meridional gradients of salinity and potential vorticity are observed in the westward directed South Equatorial Current and Equatorial Intermediate Current.
Journal Of Geophysical Research-oceans (0148-0227) (Amer Geophysical Union), 1993-12 , Vol. 98 , N. C12 , P. 22495-22520

Droits : 1993 by the American Geophysical Union.
http://archimer.ifremer.fr/doc/00192/30346/29190.pdf
DOI:10.1029/93JC02513
http://archimer.ifremer.fr/doc/00192/30346/

Éditeur(s) : HAL CCSD American Society of Tropical Medicine and Hygiene
Résumé : International audience
Anti-leishmaniasis drug resistance is a common problem worldwide. The aim of this study was to inventory the general in vitro level of sensitivity of Leishmania isolates circulating in French Guiana and to highlight potential in vitro pentamidine-resistant isolates. This sensitivity study was conducted on 36 patient-promastigote isolates for seven drugs (amphotericin B, azithromycin, fluconazole, meglumine antimoniate, miltefosine, paromomycin, and pentamidine) using the Cell Counting Kit-8 viability test. The IC50 values obtained were heterogeneous. One isolate exhibited high IC50 values for almost all drugs tested. Pentamidine, which is the first-line treatment in French Guiana, showed efficacy at very low doses (mean of 0.0038 μg/mL). The concordance of the in vitro pentamidine results with the patients' clinical outcomes was 94% (K = 0.82).
ISSN: 0002-9637

inserm-01481512
http://www.hal.inserm.fr/inserm-01481512
http://www.hal.inserm.fr/inserm-01481512/document
http://www.hal.inserm.fr/inserm-01481512/file/2017%2C%20Ginouves%20-%20In%20vitro%20sensitivity%20of%20cutaneous%20leishmania.pdf
DOI : 10.4269/ajtmh.16-0373

Éditeur(s) : HAL CCSD
Résumé : International audience
Realized in French Polynesia among 274 patients with elephantiasis, this survey studied the microfilaremia, the eosinophily, the immunoglobulin titers and the antifilarian antibodies (done by passive hemagglutination) for Wuchereria bancrofti var. pacifica. Patients with elephantiasis seldom have circulating microfilariae in their blood. Hypereosinophily is frequent but rarely high. It is similar to the one patients with microfilaremia. There is a trend towards neutropenia during lymphangitic crisis that occur on an elephantiasis limb. The IgE titer is clearly increased, the IgG one is lesser elevated. The mean values are identical to those encoutered among microfilariae asymptomatic cariers. On the other hand the serodiagnosis is more frequently positive among elephantiasic patients.
Bull Soc Pathol Exot Filiales

hal-00715424
https://hal.univ-antilles.fr/hal-00715424
PUBMED : 385164

Éditeur(s) : Copernicus Gesellschaft Mbh
Résumé : Relict dune fields that are found as far south as 14 N in the modern-day African Sahel are testament to equatorward expansions of the Sahara desert during the Late Pleistocene. However, the discontinuous nature of dune records means that abrupt millennial-timescale climate events are not always resolved. High-resolution marine core studies have identified Heinrich stadials as the dustiest periods of the last glacial in West Africa although the spatial evolution of dust export on millennial timescales has so far not been investigated. We use the major-element composition of four high-resolution marine sediment cores to reconstruct the spatial extent of Saharan-dust versus river-sediment input to the continental margin from West Africa over the last 60 ka. This allows us to map the position of the sediment composition corresponding to the Sahara Sahel boundary. Our records indicate that the Sahara Sahel boundary reached its most southerly position (13 N) during Heinrich stadials and hence suggest that these were the periods when the sand dunes formed at 14 N on the continent. Heinrich stadials are associated with cold North Atlantic sea surface temperatures which appear to have triggered abrupt increases of aridity and wind strength in the Sahel. Our study illustrates the influence of the Atlantic meridional overturning circulation on the position of the Sahara Sahel boundary and on global atmospheric dust loading.
Climate Of The Past (1814-9324) (Copernicus Gesellschaft Mbh), 2013 , Vol. 9 , N. 3 , P. 1181-1191

Droits : Author(s) 2013. CC Attribution 3.0 License. Access Climate of
http://archimer.ifremer.fr/doc/00181/29240/27635.pdf
DOI:10.5194/cp-9-1181-2013
http://archimer.ifremer.fr/doc/00181/29240/

Éditeur(s) : HAL CCSD BioMed Central
Résumé : International audience
UNLABELLED: ABSTRACT: BACKGROUND: High circulating parasite load is one of the WHO criteria for severe falciparum malaria. During a period of 11 years (2000-2010), the frequency of hyperparasitaemia (HP) (≥4% infected erythrocytes) during bouts of malaria due to Plasmodium falciparum, Plasmodium vivax and Plasmodium malariae in patients referred to Cayenne General Hospital (CGH) in French Guiana and the frequency of their admission to the Intensive Care Unit (ICU) were evaluated. METHODS: A mean of 1,150 malaria cases were referred to the Parasitology Laboratory of CGH each year over the last decade. During this period, malaria diagnostic (microscopy) and parasitaemia evaluation have remained unchanged: determination of the parasitized erythrocytes percentage with asexual forms on thin blood smears for all cases of parasitaemia exceeding 0.1%. Patients admitted to the ICU can be counted by origin of the request for malaria testing. All the data collected retrospectively were anonymized in a standardized case report form and in database. RESULTS: Between 2000 and 2010, 12,254 bouts of malaria were confirmed at the Parasitology Laboratory of CHG: P. vivax: 56.2%, P. falciparum: 39.5%, co-infection with both species: 3.4%, P. malariae: 0.9%. HP was observed in 262 cases, at a frequency of 4.9% for P. falciparum and only 0.041% for P. vivax, with no recorded cases for P. malariae. The need for intensive care was correlated with P. falciparum parasite load: 12.3% of cases for parasitaemia of 4-9%, 21.2% for parasitaemia 10-19%, 50% for parasitaemia 20-29% and 77.8% for parasitaemia ≥30% (n=9). The patient with the highest parasitaemia (75% infected erythrocytes with asexual form) presented a major concomitant lupus flare-up treated with corticoids. He survived without obvious sequelae. CONCLUSIONS: In French Guiana during bouts of malaria, HP was observed at a frequency of ~ 5% for P. falciparum and two orders of magnitude less frequent for P. vivax. HP is a severity criterion for falciparum malaria in this endemic area. However, two of the patients with HP ≥30% were not admitted to the ICU and sequel-free cure in malaria patients with 75% parasitaemia is, therefore, possible.
ISSN: 1475-2875

inserm-00780740
http://www.hal.inserm.fr/inserm-00780740
http://www.hal.inserm.fr/inserm-00780740/document
http://www.hal.inserm.fr/inserm-00780740/file/1475-2875-12-20.pdf
DOI : 10.1186/1475-2875-12-20

Éditeur(s) : American Geophysical Union
Résumé : The origins and fates of the Atlantic salinity maximum water (SMW), formed through excess evaporation in the tropics and subtropics of both hemispheres, are studied using monthly mean outputs of a numerical simulation of the world ocean climatological circulation. After defining formation domains from the surface salinity field and the vertical stratification, a Lagrangian technique is used to estimate the formation rates and main pathways in each hemisphere and the role of this water in the framework of the warm water return flow of the meridional overturning cell. Formation rates around 9 and 11 Sv are found in the Southern and Northern Hemispheres, respectively. While the export of the southern SMW from its formation area is realized by the western boundary currents, that of the northern SMW mainly results from interior subduction. Equatorward of the formation regions, a fraction of each SMW variety is entrained in the subtropical cells that connect the subtropics to the equatorial region. Poleward of them, both varieties are seen to feed the regions of subtropical mode water (STMW) formation around 35degrees of latitude in both hemispheres. The bulk of the transport associated with each variety eventually turns northward: This amounts to similar to6 Sv of southern SMW gathered in the North Brazil Undercurrent (NBUC), and similar to10 Sv of northern SMW found in the Gulf Stream at 35degreesN, of which 8 Sv have gone through the Caribbean Sea. Of the 13.4-Sv northward transport of the meridional overturning cell estimated by the model at 47degreesN, more than 50% (6.9 Sv) is found to have transited through at least one of the SMW regions. This gives an indication of the likely important role of SMW formation in the observed northward salinity increase of the upper Atlantic Ocean.
Journal of Geophysical Union - Research C - Oceans (0148-0227) (American Geophysical Union), 2002-09 , Vol. 107 , N. C10 , P. NIL_610-NIL_624

Droits : 2002 by the American Geophysical Union
http://archimer.ifremer.fr/doc/2002/publication-769.pdf
DOI:10.1029/2002JC001318
http://archimer.ifremer.fr/doc/00000/769/

Éditeur(s) : Amer Geophysical Union
Résumé : The meridional transport of salt in the Atlantic ocean is an important process for climate, controlling the stability of the meridional overturning circulation. The contribution of transient eddies to this transport is quantified in an eddy resolving North Atlantic model at 1/12 degrees resolution (NATL12), and compared with lower resolution North-Atlantic and global 1/4 degrees models. In NATL12 between 10 degrees N and 40 degrees N, there is a volume loss by evaporation of 0.6 Sverdrups (Sv). The divergence of the eddy flux of salt (normalized by a reference salinity of 34.8) is 0.2 Sv over the region, a significant fraction of the total air-seawater exchange, but it is compensated by an opposite convergent transport of salt by the mean flow, so that the total transport of salt is small. The compensation between eddy and mean salt transport is almost complete in a multicentury long global model experiment, but less effective in NATL12 because the short integration time does not allow the salt content to equilibrate and the model drift is large. Eddies arising from baroclinic instability contribute to the meridional salt transports at the northern and southern boundary of the subtropical gyre, where they appear consistent with a lateral diffusion acting on the mean salinity gradient. However, the eddy transport of salt is the sum of two terms: an advective contribution (arising from the correlations of velocity and isopycnal thicknesses) and a diffusion along isopycnals. Both components have the same amplitude at the southern boundary of the subtropical gyre, while diffusion is dominant at the northern boundary.
Journal Of Geophysical Research-oceans (0148-0227) (Amer Geophysical Union), 2012-05 , Vol. 117 , N. C05010 , P. 19 pp.

Droits : 2012 AGU
http://archimer.ifremer.fr/doc/00083/19441/17052.pdf
DOI:10.1029/2012JC007927
http://archimer.ifremer.fr/doc/00083/19441/