The effect of fatty acid surfactants on the uptake of nitric acid to deliquesced NaCl aerosol

Surface active organic compounds have been observed in marine boundary layer aerosol. Here, we investigate the effect such surfactants have on the uptake of nitric acid (HNO<sub>3</sub>), an important removal reaction of nitrogen oxides in the marine boundary layer. The uptake of gaseous HNO<sub>3</sub> on deliquesced NaCl aerosol was measured in a flow reactor using HNO<sub>3</sub> labelled with the short-lived radioactive isotope <sup>13</sup>N. The uptake coefficient γ on pure deliquesced NaCl aerosol was γ=0.5±0.2 at 60% relative humidity and 30 ppb HNO<sub>3</sub>(g). The uptake coefficient was reduced by a factor of 5–50 when the aerosol was coated with saturated linear fatty acids with carbon chain lengths of 18 and 15 atoms in monolayer quantities. In contrast, neither shorter saturated linear fatty acids with 12 and 9 carbon atoms, nor coatings with the unsaturated oleic acid (C18, cis-double bond) had a detectable effect on the rate of HNO<sub>3</sub> uptake. It is concluded that it is the structure of the monolayers formed, which determines their resistance towards HNO<sub>3</sub> uptake. Fatty acids (C18 and C15), which form a highly ordered film in the so-called liquid condensed state, represent a significant barrier towards HNO<sub>3</sub> uptake, while monolayers of shorter-chain fatty acids (C9, C12) and of the unsaturated oleic acid form a less ordered film in the liquid expanded state and do not hinder the uptake. Similarly, high contents of humic acids in the aerosol, a structurally inhomogeneous, quite water soluble mixture of oxidised high molecular weight organic compounds did not affect HNO<sub>3</sub> uptake. As surfactant films on naturally occurring aerosol are expected to be less structured due to their chemical inhomogeneity, it is likely that their inhibitory effect on HNO<sub>3</sub> uptake is smaller than that observed here for the C15 and C18 fatty acid monolayers

In situ quantification of CH4 bubbling events from a peat soil using a new infrared laser spectrometer

International audienceCH4 emissions from peatlands are space- and time-dependent. The variety of efflux routes contributes to these variabilities. CH4 bubbling remains difficult to investigate since it occurs on a timescale of seconds. The aims of this study were to test the capacity of a recently built infrared high resolution spectrometer, SPIRIT (SPectrometre Infra-Rouge In situ Troposphérique), to (1) measure in situ CH4 fluxes, (2) observe online bubbling events with quantification of CH4 emission fluxes corresponding to this very sudden degassing event. Material and methods: The closed dynamic chamber method was used and the gas concentration was measured every 1.5 seconds. Emission fluxes were calculated by the accumulation rate of CH4 against time. Measurements were undertaken during daytime in March 2009 and during day- and nighttime in May 2009, in a bare peat area, temporarily forming a shallow pool. Results and discussion: The results show that the CH4 emissions estimated with the SPIRIT ranged from 2.79 to 86.0 mg CH4-C m-2 h-1. These values are consistent with those already published. The high emissions, both through diffusion and bubbling, were on the same order as the emissions estimated in natural shallow pools. During daytime, CH4 bubbling was higher in May (56.2% of the total emission) than in March (40.7%) probably because of increased CH4 production and accumulation in peat. In May, bubbling was higher at nighttime (68.6%) than in daytime (56.2%). This has an important implication for carbon budget assessment in peatlands, particularly in boreal areas. Conclusions: The recently built infrared spectrometer, SPIRIT, was able to reliably measure CH4 fluxes and quantify CH4 flux during the degassing of a bubble. The emissions obtained are in agreement with previously published data using other measurement techniques. The results of this preliminary work highlight (1) the importance of shallow pools in peatland CH4 emissions, (2) the sensitivity of such fluxes to atmospheric pressure, a relation that has not been fully investigated or taken into account in assessing peatland carbon balance

Recombination-prone bacterial strains form a reservoir from which epidemic clones emerge in agroecosystems

The acquisition of virulence-related genes through horizontal gene transfer can modify the pathogenic profiles of strains and lead to the emergence of new diseases. Xanthomonas arboricola is a bacterial species largely known for the damage it causes to stone and nut fruit trees worldwide. In addition to these host-specific populations called pathovars, many nonpathogenic strains have been identified in this species. Their evolutionary significance in the context of pathogen emergence is unknown. We looked at seven housekeeping genes amplified from 187 pathogenic and nonpathogenic strains isolated from various plants worldwide to analyze population genetics and recombination dynamics. We also examined the dynamics of the gains and losses of genes associated with life history traits (LHTs) during X. arboricola evolution. We discovered that X. arboricola presents an epidemic population structure. Successful pathovars of trees (i.e. pruni, corylina and juglandis) are epidemic clones whose emergence appears to be linked to the acquisition of eight genes coding for Type III effectors. The other strains of this species are part of a recombinant network, within which LHT-associated genes might have been lost. We suggest that nonpathogenic strains, because of their high genetic diversity and propensity for recombination, may promote the emergence of pathogenic strains

Effects of experimental warming on carbon sink function of a temperate pristine mire : the PEATWARM project.

communication oraleInternational audienceWithin the PEATWARM project, we use Sphagnum peatlands as a model to analyse their vulnerability to climate change using an experimental system (ITEX) that simulates in situ an increase in average temperature. We aim to determine the effects of temperature increase on the vegetation, the balance of above- and belowground gas fluxes (CO2 and CH4), the microbial diversity and activity in Sphagnum mosses and in peat, and the dynamics of labile and recalcitrant organic matter of peat. The ultimate objective is the creation of a biogeochemical model of C coupled with N and S cycles that includes interactions between these key compartments

Stratospheric aerosols from the Sarychev volcano eruption in the 2009 Arctic summer

Aerosols from the Sarychev volcano eruption (Kuril Islands, northeast of Japan) were observed in the Arctic lower stratosphere a few days after the strongest SO2 injection which occurred on 15 and 16 June 2009. From the observations provided by the Infrared Atmospheric Sounding Interferometer (IASI) an estimated 0.9 Tg of sulphur dioxide was injected into the upper troposphere and lower stratosphere (UTLS). The resultant stratospheric sulphate aerosols were detected from satellites by the Optical Spectrograph and Infrared Imaging System (OSIRIS) limb sounder and by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and from the surface by the Network for the Detection of Atmospheric Composition Changes (NDACC) lidar deployed at OHP (Observatoire de Haute-Provence, France). By the first week of July the aerosol plume had spread out over the entire Arctic region. The Sarychev-induced stratospheric aerosol over the Kiruna region (north of Sweden) was measured by the Stratospheric and Tropospheric Aerosol Counter (STAC) during eight balloon flights planned in August and September 2009. During this balloon campaign the Micro Radiomètre Ballon (MicroRADIBAL) and the Spectroscopie d'Absorption Lunaire pour l'Observation des Minoritaires Ozone et NOx (SALOMON) remote-sensing instruments also observed these aerosols. Aerosol concentrations returned to near-background levels by spring 2010. The effective radius, the surface area density (SAD), the aerosol extinction, and the total sulphur mass from STAC in situ measurements are enhanced with mean values in the range 0.15-0.21 μm, 5.5-14.7 μm2 cm-3, 5.5-29.5 × 10-4 km-1, and 4.9-12.6 × 10-10 kg[S] kg-1[air], respectively, between 14 km and 18 km. The observed and modelled e-folding time of sulphate aerosols from the Sarychev eruption is around 70-80 days, a value much shorter than the 12-14 months calculated for aerosols from the 1991 eruption of Mt Pinatubo. The OSIRIS stratospheric aerosol optical depth (AOD) at 750 nm is enhanced by a factor of 6, with a value of 0.02 in late July compared to 0.0035 before the eruption. The HadGEM2 and MIMOSA model outputs indicate that aerosol layers in polar region up to 14-15 km are largely modulated by stratosphere-troposphere exchange processes. The spatial extent of the Sarychev plume is well represented in the HadGEM2 model with lower altitudes of the plume being controlled by upper tropospheric troughs which displace the plume downward and upper altitudes around 18-20 km, in agreement with lidar observations. Good consistency is found between the HadGEM2 sulphur mass density and the value inferred from the STAC observations, with a maximum located about 1 km above the tropopause ranging from 1 to 2 × 10 -9 kg[S] kg-1[air], which is one order of magnitude higher than the background level. © Author(s) 2013.The authors thank the CNES balloon launching team for successful operations and the Swedish Space Corporation at Esrange. The ETHER database (CNES-INSUCNRS) and the CNES “sous-direction Ballon” are partners of the project. The StraPolEt ´ e project has been funded by the French ´ “Agence Nationale de la Recherche” (ANR-BLAN08-1-31627), the “Centre National d’Etudes Spatiales” (CNES), and the “Institut ´ Polaire Paul-Emile Victor” (IPEV). The AEROWAVE (Aerosols, Water Vapor and Electricity) and the HALOHA (HALOgen in High Altitudes) projects have been funded by the recently created French CNES-INSU Balloon Committee (so-called CSTB). We are grateful to Slimane Bekki and David Cugniet for their constructive comments about the AER-UPMC 2-D model, to Marc-Antoine Drouin for his help about the MIMOSA model, and to the LPC2E technical team for this successful campaign. Jim Haywood and Andy Jones were supported by the Joint DECC/Defra Met Office Hadley Centre Climate Programme (GA01101). IASI was developed and built under the responsibility of the Centre National d’Etudes Spatiales (CNES, France). It is flown on board the Metop ´ satellites as part of the EUMETSAT Polar System. The IASI L1 data are received through the EUMETCast near-real-time data distribution service. L. Clarisse is a postdoctoral researcher with FRS-FNRS. We acknowledge the CALIOP team for acquiring and processing data as well as the ICARE team for providing and maintaining the computational facilities to store them. Odin is a Swedish-led satellite project funded jointly by Sweden (SNSB), Canada (CSA), France (CNES), and Finland (Tekes). This study was supported by the French VOLTAIRE Labex (Laboratoire d’Excellence ANR-10-LABX-100-01) managed by the University of Orleans

Phase II Study of BEZ235 versus Everolimus in Patients with Mammalian Target of Rapamycin Inhibitor‐Naïve Advanced Pancreatic Neuroendocrine Tumors

BACKGROUND: This phase II study investigated whether targeting the phosphatidylinositol 3‐kinase (PI3K)/mammalian target of rapamycin (mTOR) pathway via PI3K, mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2) inhibition using BEZ235 may be more effective than mTORC1 inhibition with everolimus in patients with advanced pancreatic neuroendocrine tumors (pNET) who are naïve to mTOR inhibitor therapy. METHODS: Patients with advanced pNET were randomized (1:1) to oral BEZ235 400 mg twice daily or oral everolimus 10 mg once daily on a continuous dosing schedule. The primary endpoint was progression‐free survival (PFS). Secondary endpoints included safety, overall response rate (ORR), overall survival (OS), and time to treatment failure. RESULTS: Enrollment in this study was terminated early (62 enrolled of the 140 planned). The median PFS was 8.2 months (95% confidence interval [CI]: 5.3 to not evaluable [NE]) with BEZ235 versus 10.8 months (95% CI: 8.1–NE) with everolimus (hazard ratio 1.53; 95% CI: 0.72–3.25). The most commonly reported all‐grade adverse events (>50% of patients regardless of study treatment relationship) with BEZ235 were diarrhea (90.3%), stomatitis (74.2%), and nausea (54.8%). CONCLUSION: BEZ235 treatment in mTOR inhibitor‐naïve patients with advanced pNET did not demonstrate increased efficacy compared with everolimus and may be associated with a poorer tolerability profile

Efficacy of everolimus in patients with metastatic insulinoma and refractory hypoglycemia

BACKGROUND: Refractory hypoglycemia in patients with metastatic insulinoma is an important cause of morbidity and mortality. Everolimus could be a new therapeutic option. METHODS: Within the French Group, we conducted a retrospective, multicentric study of endocrine tumors to evaluate the time to the first recurrence of symptomatic hypoglycemia, after everolimus initiation, in patients with metastatic insulinoma and refractory hypoglycemia. Ongoing hyperglycemic medical options, tumor response, and safety information were recorded. RESULTS: Twelve patients with metastatic insulinoma and refractory hypoglycemia who were treated with everolimus between May 2007 and June 2011 were reviewed. Everolimus (starting dose, 10 mg/day, except in one patient, 5 mg/day) was given after a median of four previous therapeutic lines. Medication aimed at normalizing blood glucose levels in 11 patients. After a median duration of 6.5 months (range 1-35+ months), median time to the first recurrence of symptomatic hypoglycemia was 6.5 months (range 0 to 35+ months). Three patients discontinued everolimus because of cardiac and/or pulmonary adverse events at 1, 1.5, and 7 months after initiation, which led to two deaths. Three patients discontinued everolimus because of tumor progression at 2, 3, and 10 months after initiation, without recurrence of hypoglycemia. CONCLUSION: Everolimus appears to be a new effective treatment for patients with metastatic insulinoma and refractory hypoglycemia. Tolerance should be carefully monitored

Polarized secretion of Leukemia Inhibitory Factor

<p>Abstract</p> <p>Background</p> <p>The direction of cytokine secretion from polarized cells determines the cytokine's cellular targets. Leukemia inhibitory factor (LIF) belongs to the interleukin-6 (IL-6) family of cytokines and signals through LIFR/gp130. Three factors which may regulate the direction of LIF secretion were studied: the site of stimulation, signal peptides, and expression levels. Stimulation with IL-1β is known to promote IL-6 secretion from the stimulated membrane (apical or basolateral) in the human intestinal epithelial cell line Caco-2. Since LIF is related to IL-6, LIF secretion was also tested in Caco-2 following IL-1β stimulation. Signal peptides may influence the trafficking of LIF. Two isoforms of murine LIF, LIF-M and LIF-D, encode different signal peptides which have been associated with different locations of the mature protein in fibroblasts. To determine the effect of the signal peptides on LIF secretion, secretion levels were compared in Madin-Darby canine kidney (MDCK) clones which expressed murine LIF-M or LIF-D or human LIF under the control of an inducible promoter. Low and high levels of LIF expression were also compared since saturation of the apical or basolateral route would reveal specific transporters for LIF.</p> <p>Results</p> <p>When Caco-2 was grown on permeable supports, LIF was secreted constitutively with around 40% secreted into the apical chamber. Stimulation with IL-1β increased LIF production. After treating the apical surface with IL-1β, the percentage secreted apically remained similar to the untreated, whereas, when the cells were stimulated at the basolateral surface only 20% was secreted apically. In MDCK cells, an endogenous LIF-like protein was detected entirely in the apical compartment. The two mLIF isoforms showed no difference in their secretion patterns in MDCK. Interestingly, about 70% of murine and human LIF was secreted apically from MDCK over a 400-fold range of expression levels within clones and a 200,000-fold range across clones.</p> <p>Conclusion</p> <p>The site of stimulation affected the polarity of LIF secretion, while, signal peptides and expression levels did not. Exogenous LIF is transported in MDCK without readily saturated steps.</p

Chemotherapy for Well-Differentiated Pancreatic Neuroendocrine Tumours with a Ki-67 Index ≥10%: Is There a More Effective Antitumour Regimen? A Retrospective Multicentre Study of the French Group of Endocrine Tumours (GTE)

BACKGROUND: The best chemotherapy regimen for well- differentiated pancreatic neuroendocrine tumours (pNETs) with a Ki-67 index ≥10% is still debated. We evaluated the antitumour efficacy of various first-line chemotherapy regimens (streptozocin based, platinum based, or dacarbazine/temozolomide based) in this situation. METHODS: In this retrospective multicentre study of the French Group of Endocrine Tumours (GTE), we recruited consecutive patients with advanced well-differentiated pNETs and a Ki-67 index ≥10% receiving chemotherapy between 2000 and 2012. The primary endpoint was progression-free survival (PFS) according to RECIST. RESULTS: Seventy-four patients (42 men, median age 55.5 years) were enrolled from 10 centres. Fifty-one patients (69%) had grade 2 NET and 61 (82%) were stage IV. Median overall survival was 36.3 months. Forty-four patients (59%) received streptozocin-based, 18 (24%) platinum-based, and 12 (16%) dacarbazine/temozolomide-based chemotherapy regimens. These 3 groups were similar regarding age, functioning tumours, grade, the number of metastatic sites, and surgery for primary tumours, but not regarding surgery for metastases and time since diagnosis. Grade 3 NET (HR 2.15, 95% CI: 1.18-3.92, p = 0.012) and age above 55 years (HR 1.84, 95% CI: 1.06-3.18, p = 0.030) were associated with shorter median PFS in the multivariate analyses. Compared to streptozocin-based chemotherapy, no difference was found in terms of PFS for the platinum-based or for the dacarbazine/temozolomide-based chemotherapy regimen: median PFS was 7.2, 7.5, and 7.2 months, respectively (p = 0.51). CONCLUSIONS: Patients with intermediate or highly proliferative well-differentiated pNETs may benefit from 1 of the 3 chemotherapy regimens. Increased age and grade 3 were associated with shorter median PFS. Randomised studies searching for response predictors and the best efficacy-tolerance ratio are required to personalise the strategy