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Distribution des formes de relief et des dépôts sédimentaires enfouis pendant la croissance du delta du fleuve Aceh (Sumatra, Indonésie)
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Erythrocytosis associated with IgA nephropathy
No full textInternational audienceBackground Erythrocytosis is a hematological disorder usually related to hematopoietic stem cell somatic muta-tions. However, unexplained erythrocytosis remains frequent. In this study, we evaluated the involvement of IgA1, a regulator of erythropoiesis also implicated in IgA nephropathy (IgAN) pathophysiology, in unexplained polycythe-mia/erythrocytosis (PE) of IgAN patients.Methods IgAN-PE patients’ serum was collected, analyzed and used to study IgA1 effect on proliferation and differ-entiation of erythroid progenitors. Hematological parameters of transgenic mice for human alpha1 heavy chain were studied. Multicentric observational cohorts of chronic kidney disease (CKD) patients, including both native kidney diseases and renal transplants, were studied to analyze patient hemoglobin levels.Findings We retrospectively identified 6 patients with IgAN and unexplained PE. In large CKD cohorts, IgAN was associated with PE in 3.5% of patients (p<0.001 compared to other nephropathies). IgAN was an independent factor associated with higher hemoglobin levels (13.1g/dL vs 12.2 g/dL, p=0.01). During post-transplant anemia, anemia recovery was faster in IgAN patients. Elevated polymeric/monomeric IgA1 ratio as well as high Gd-IgA1 rate were observed in circulating IgA1 of the 6 IgAN-PE patients as compared with control or IgAN patients without PE. IgA1 from these patients increased the sensitivity of erythroid progenitors to Epo. In mice, we also observed an elevation of hematocrit in alpha1 knock-in mice compared to wild type controls.Interpretation These data identify a new etiology of erythrocytosis and demonstrate the role of pIgA1 in human erythropoiesis. This syndrome of IgA-related erythrocytosis should be investigated in case of unexplained erythrocy-tosis and renal disease
Network meta‐analysis: methodological points for readers, authors and reviewers
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H2O2-Responsive Nanocarriers Prepared by RAFT-Mediated Polymerization-Induced Self-Assembly of N -(2-(Methylthio)ethyl)acrylamide for Biomedical Applications
No full textInternational audienceH2O2-sensitive block copolymer nanoparticles (NPs) composed of a hydrophilic macro-chain transfer agent (macro-CTA) and a hydrophobic thioether-bearing block were prepared by polymerization-induced self-assembly (PISA) approach. The PISA process first involved the chain extension of poly((poly(ethylene glycol) methyl ether methacrylate)-co-(poly(ethylene glycol) methacrylate)) macro-CTA with a H2O2-responsive N-(2-(methylthio)ethyl)acrylamide (MTEAM) monomer, which self-assembled into P((PEGMA-co-PEGMAOH)-b-PMTEAM) block copolymer NPs. The polymerization kinetics indicated the evolution of particle size and morphology from spherical micelles, fused micelles, to vesicles over time. Upon incubation with 0.1 to 10 mM H2O2, spheres were fragmented due to the oxidation of the PMTEAM cores, thus transforming the hydrophobic thioethers into hydrophilic sulfoxides and disassociating the nanocarriers. 43% of the hydrophobic Nile red dye was encapsulated into the spherical micelles and demonstrated a controlled release in H2O2 incubation. Spherical micelles and vesicles displayed no cytotoxicity in MCF-7, DU145, and 22Rv1 cells. Both spheres and vesicles were efficiently internalized into MCF-7 cells, with spheres showing a higher level of uptake than vesicles due to the smaller sizes. In summary, PISA of P((PEGMA-co-PEGMAOH)-b-PMTEAM) allowed the direct formation and loading of hydrophobic dye into spherical micelles, which showed a controlled drug release in H2O2
A Moser/Bernstein type theorem in a Lie group with a left invariant metric under a gradient decay condition
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Kinetics, Products, and Brown Carbon Formation by Aqueous-Phase Reactions of Glycolaldehyde with Atmospheric Amines and Ammonium Sulfate
No full textInternational audienceGlycolaldehyde (GAld) is a C2 water-soluble aldehyde produced during the atmospheric oxidation of isoprene and many other species and is commonly found in cloudwater. Previous work has established that glycolaldehyde evaporates more readily from drying aerosol droplets containing ammonium sulfate (AS) than does glyoxal, methylglyoxal, or hydroxyacetone, which implies that it does not oligomerize as quickly as these other species. Here, we report NMR measurements of glycolaldehyde’s aqueous-phase reactions with AS, methylamine, and glycine. Reaction rate constants are smaller than those of respective glyoxal and methylglyoxal reactions in the pH range of 3–6. In follow-up cloud chamber experiments, deliquesced glycine and AS seed particles were found to take up glycolaldehyde and methylamine and form brown carbon. At very high relative humidity, these changes were more than 2 orders of magnitude faster than predicted by our bulk liquid NMR kinetics measurements, suggesting that reactions involving surface-active species at crowded air–water interfaces may play an important role. The high-resolution liquid chromatography–electrospray ionization–mass spectrometric analysis of filter extracts of unprocessed AS + GAld seed particles identified sugar-like C6 and C12 GAld oligomers, including proposed product 3-deoxyglucosone, with and without modification by reactions with ammonia to diimine and imidazole forms. Chamber exposure to methylamine gas, cloud processing, and simulated sunlight increased the incorporation of both ammonia and methylamine into oligomers. Many C4–C16 imidazole derivatives were detected in an extract of chamber-exposed aerosol along with a predominance of N-derivatized C6 and C12 glycolaldehyde oligomers, suggesting that GAld is capable of forming brown carbon SO
The evolution and dynamics of the Hunga Tonga–Hunga Ha’apai sulfate aerosol plume in the stratosphere
No full textInternational audienceWe use a combination of space-borne instruments to study the unprecedented stratospheric plume after the Hunga Tonga eruption of 15 January 2022. The plume was formed of two initial clouds at 30 and 28 km mostly composed of submicronic sulphate particles without ashes, washed-out within the first hours. The large amount of water vapour injected led to a fast conversion of SO 2 to sulphates and induced a descent of the plume over the first three weeks by radiative cooling. While SO 2 returned to background levels by the end of January, the sulphate plume persisted until June, mainly confined between 20 • N and 35 • S due to the zonal symmetry of the summer stratospheric circulation at 24-25 km. As sulphate particles grew through hydration and coagulation, they sediment and separate from the ascending moisture entrained in the Brewer-Dobson circulation. Sulphate aerosol optical depths derived from the IASI infared sounder show that the aerosol plume was not simply diluted and dispersed passively but rather organized in concentrated patches. Winds from the space-borne Doppler lidar ALADIN/AEOLUS suggest that those structures, generated by shear-induced instabilities, are associated with vorticity anomalies. They likely enhance the duration and impacts of the plume
Stabilité des réseaux trophiques et impacts des changements globaux
No full textThe stability of food webs and its relation to diversity and network complexity have been subject to a lot of attention from theoretical studies in ecology. However, those studies have been criticised for the way they represented stability, because they were mainly using stability measures that were not comparable with stability measures in experimental and observational studies. In addition, while the stability of ecosystem functioning has received strong attention in the context of plant communities, it has yet been understudied in food webs. During my Ph.D., I studied the stability of ecosystem functioning in food webs with measures that can be compared with experimental and observational studies. I first studied the temporal variability of the total biomass and its relation with diversity and food web structure. I showed that in my model diversity and synchrony were less important for the temporal stability of animal community than found previously for plant communities. I then studied the impacts of warming and eutrophication as perturbations on the functioning and stability of ecosystems. My second article focused on press (long term) perturbations. I showed that, by including nutrient dynamics and updated relations between temperature and species consumption rates, competition and inedible plants had strong impacts on ecosystem response to perturbations, leading to an absence of the paradox of enrichment and no antagonistic interactions between warming and eutrophication, as opposed to what is commonly found. Finally, I studied in my third chapter the multidimensionality of stability of ecosystems under pulse (short term) perturbations. In this model, while both perturbations had short term effects of similar amplitude, warming had stronger long-term impacts, long after the perturbation was over. Overall, my results highlight that food web complexity affects our understanding of the stability of ecosystem functioning and stability is a multidimensional concept that cannot be simplified into a single dimension.La stabilité des réseaux trophiques, et leur relation avec la diversité et la complexité des réseaux, est un sujet qui a reçu beaucoup d’attention de la part des études théoriques en écologie. Cependant, ces études ont été critiquées pour leur représentation de la stabilité, car elles utilisent des mesures de stabilité qui ne sont pas comparables avec celles des études expérimentales et d’observations. De plus, alors que la stabilité du fonctionnement des écosystèmes a été bien étudiée dans le contexte des communautés végétale, celle-ci reste encore trop peu abordée dans les réseaux trophiques. C’est dans ce contexte que s’inscrit cette thèse, où j’ai étudié la stabilité du fonctionnement des réseaux trophiques avec des mesures de stabilité applicables dans les études expérimentales et d'observations. Je me suis d’abord intéressé à la variabilité temporelle de la biomasse totale et à sa relation avec la diversité et la structure des réseaux trophiques. J'ai montré que dans mon modèle la diversité et la synchronie étaient moins importantes pour la stabilité de la communauté des animaux que ce qui avait été montré pour les plantes. J’ai ensuite étudié l’impact de perturbations de type réchauffement et eutrophisation sur le fonctionnement et la stabilité des écosystèmes. Ma deuxième étude a ainsi porté sur des perturbations de long terme (press). J’ai montré que, en incluant la dynamique des nutriments et une mise à jour récente des relations entre température et taux de consommation des espèces, la compétition et les plantes non-comestibles avaient un impact fort sur la réponse des écosystèmes aux perturbations, au point de faire disparaître le paradoxe de l’enrichissement et les interactions antagonistes entre réchauffement et eutrophisation trouvés dans d’autres études. Enfin, j’ai étudié la multidimensionnalité de la stabilité face à des perturbations de court terme (pulse) dans mon troisième chapitre. Dans mon modèle, bien que les deux types de perturbation avaient des effets sur la stabilité de même amplitude à court terme, le réchauffement avait des effets à long terme bien plus fort, longtemps après s’être arrêté. Globalement, mes résultats ont souligné que la complexité des réseaux trophiques affecte notre compréhension de la stabilité du fonctionnement des écosystèmes, et que la stabilité est un concept multidimensionnel qui ne peut pas être simplifié en une seule dimension