Evidence of trophic transfer of microcystins from the gastropod Lymnaea stagnalis to the fish Gasterosteus aculeatus.

International audienceAccording to our previous results the gastropod Lymnaea stagnalis exposed to MC-producing cyanobacteria accumulates microcystins (MCs) both as free and covalently bound forms in its tissues, therefore representing a potential risk of MC transfer through the food web. This study demonstrates in a laboratory experiment the transfer of free and bound MCs from L. stagnalis intoxicated by MC-producing Planktothrix agardhii ingestion to the fish Gasterosteus aculeatus. Fish were fed during five days with digestive glands of L. stagnalis containing various concentrations of free and bound MCs, then with toxin-free digestive glands during a 5-day depuration period. MC accumulation was measured in gastropod digestive gland and in various fish organs (liver, muscle, kidney, and gills). The impact on fish was evaluated through detoxification enzyme (glutathion-S-transferase, glutathion peroxydase and superoxyde dismutase) activities, hepatic histopathology, and modifications in gill ventilation, feeding and locomotion. G. aculeatus ingestion rate was similar with intoxicated and toxin-free diet. Fish accumulated MCs (up to 3.96 ± 0.14 μg g−1 DW) in all organs and in decreasing order in liver, muscle, kidney and gills. Hepatic histopathology was moderate. Glutathion peroxydase was activated in gills during intoxication suggesting a slight reactive oxygen species production, but without any impact on gill ventilation. Intoxication via ingestion of MC-intoxicated snails impacted fish locomotion. Intoxicated fish remained significantly less mobile than controls during the intoxication period possibly due to a lower health condition, whereas they showed a greater mobility during the depuration period that might be related to an acute foraging for food. During depuration, MC elimination was total in gills and kidney, but partial in liver and muscle. Our results assess the MC transfer from gastropods to fish and the potential risk induced by bound MCs in the food web

Atmospheric plasma spraying coatings from alumina titania feedstockcomprising bimodal particle size distributions

In this work, Al2O3 13 wt% TiO2 submicron-nanostructured powders were deposited using atmospheric plasma spraying. The feedstocks were obtained by spray drying two starting suspensions of different solids content, prepared by adding nanosized TiO2 and submicron-sized Al2O3 powders to water. The spray-dried granules were heat-treated to reduce their porosity and the powders were fully characterised in both untreated and thermally treated state. Comparison with two commercial feedstocks was carried out. Characterisation allowed a temperature for the thermal treatment to be chosen on the basis of the sprayability of the feedstock and the preservation as much as possible of the submicron-sized structure of the unfired agglomerates. Optimisation of the deposition conditions enabled the reconstituted powdrs to be successfully deposited, yielding coatings that were well bonded to the substrate. The coating microstructure, characterised by SEM, was mostly formed by a matrix of fully molten particles where the presence of semi-molten feedstock agglomerates was also observed. Moreover, microhardness, toughness, adhesion and tribological behaviours were determined, and the impact of the granule characteristics on these properties was studied. It was found that changing the feedstock characteristics allows controlling the coating quality and properties. In general, good mechanical properties were obtained using a feedstock comprising a binary mixture of submicrometric Al2O3 and nanometric TiO2 particles in the spray-dried powderThis work has been supported by Spanish Ministry of Economy and Competitiveness (MAT2009-14144-C03 and MAT2012-38364-C03).Vicent, M.; Bannier, E.; Moreno, R.; Salvador Moya, MD.; Sanchez, E. (2013). Atmospheric plasma spraying coatings from alumina titania feedstockcomprising bimodal particle size distributions. Journal of the European Ceramic Society. 33:3313-3324. doi:10.1016/j.jeurceramsoc.2013.05.009S331333243

Multilayer and particle size-graded YSZ coatings obtained by plasma spraying of micro- and nanostructured feedstocks

This work was supported by the Spanish Ministry of Science and Innovation (Project MAT2012-38364-C03) and the Research Promotion Plan of Universitat Jaume I, action 3.1 (Ref. PREDOC/2009/10), and it has been co-funded by the European Regional Development Fund (ERDF). The authors also thank the SCIC of Universitat Jaume I for the FEG-SEM observationsCarpio, P.; Bannier, E.; Salvador Moya, MD.; Benavente Martínez, R.; Sanchez Vilches, E. (2014). Multilayer and particle size-graded YSZ coatings obtained by plasma spraying of micro- and nanostructured feedstocks. Journal of Thermal Spray Technology. 23(8):1362-1372. https://doi.org/10.1007/s11666-014-0143-9S13621372238D.R. Clarke and S.R. Phillpot, Thermal Barrier Coatings Materials, Mater. Today, 2005, 8, p 22-29N.P. Patdure, M. Gell, and E.H. Jordan, Thermal Barrier Coatings for Gas-Turbine Engine Applications, Science, 2002, 296, p 280-284L. Pawlowski, Finely Grained Nanometric and Submicrometric Coatings by Thermal Spraying: A Review, Surf. Coat. Technol., 2008, 205(43), p 18-28R.S. Lima and B.R. Marple, Thermal Spray Coatings Engineered from Nanostructured Ceramic Agglomerated Powders for Structural, Thermal Barrier and Biomedical Applications: A Review, J. Therm. Spray Technol., 2007, 16(1), p 40-63P. Fauchais, G. Montavon, R.S. Lima, and B.R. Marple, Engineering a New Class of Thermal Spray Nano-Based Microstructures from Agglomerated Nanostructured Particles, Suspensions and Solutions: An Invited Review, J. Phys. D, 2011, 44(9), 93001, p 1-131M. Gell, E.H. Jordan, Y.H. Sohn, D. Goberman, L. Shaw, and T.D. Xiao, Development and Implementation of Plasma Sprayed Nanostructured Ceramic Coatings, Surf. Coat. Technol., 2001, 146-147, p 48-54R.S. Lima and B.R. Marple, Nanostructured YSZ Thermal Barrier Coatings Engineered to Counteract Sintering Effects, Mater. Sci. Eng. A, 2008, 485, p 182-193H. Chen, X. Zhou, and C. Ding, Investigation of the Thermomechanical Properties of a Plasma-Sprayed Nanostructured Zirconia Coating, J. Eur. Ceram. Soc., 2003, 23, p 1449-1455K.A. Khor and Y.W. Gu, Thermal Properties of Plasma-Sprayed Graded Thermal Barrier Coatings, Thin Solid Films, 2000, 372, p 104-113A.M. Limarga, T.S. Widjajab, and T.H. Yip, Mechanical Properties and Oxidation Resistance of Plasma-Sprayed Multilayered Al2O3/ZrO2 Thermal Barrier Coatings, Surf. Coat. Technol., 2005, 197, p 93-102X. Chen, Y. Zhao, X. Fan, Y. Liu, B. Zou, Y. Wang, H. Ma, and X. Cao, Thermal Cycling Failure of New LaMgAl11O19/YSZ Double Ceramic Top Coat Thermal Barrier Coating Systems, Surf. Coat. Technol., 2011, 205, p 3293-3300G. Mauer, M.O. Jarligo, D.E. Mack, and R. Vassen, Plasma-Sprayed Thermal Barrier Coatings: New Materials, Processing Issues and Solutions, J. Therm. Spray Technol., 2013, 22(5), p 647-658A. Portinha, V. Teixeira, J. Carneiro, J. Martins, M.F. Costa, R. Vassen, and D. Stoever, Characterization of Thermal Barrier Coatings with a Gradient in Porosity, Surf. Coat. Technol., 2005, 195, p 245-251M. Vicent, E. Sánchez, G. Mallol, and R. Moreno, Study of Colloidal Behaviour and Rheology of Al2O3-TiO2 Nanosuspensions to Obtain Free-Flowing Spray-Dried Granules for Atmospheric Plasma Spraying, Ceram. Int., 2013, 39(7), p 8103-8111F. Müller, W. Peukert, R. Polke, and R. Stenger, Dispersing Nanoparticles in Liquids, Int. J. Miner. Process., 2000, 74, p S31-S34M. Vicent, E. Bannier, R. Moreno, M.D. Salvador, and E. Sánchez, Atmospheric Plasma Spraying Coatings from Alumina-Titania Feedstock Comprising Bimodal Particle Size Distributions, J. Eur. Ceram. Soc., 2013, 33, p 3313-3324C.W. Kang and H.W. Ng, Splat Morphology and Spreading Behaviour due to Oblique Impact of Droplets onto Substrates in Plasma Spray Coating Process, Surf. Coat. Technol., 2006, 200, p 5462-5477Y. Zeng, S.W. Lee, L. Gao, and C.X. Ding, Atmospheric Plasma Sprayed Coatings of Nanostructured Zirconia, J. Eur. Ceram. Soc., 2002, 22, p 347-351R.S. Lima, A. Kucuk, and C.C. Berndt, Integrity of Nanostructured Partially Stabilized Zirconia After Plasma Spray Processing, Mater. Sci. Eng. A, 2001, 13, p 75-82L. Wang, Y. Wang, X.G. Sun, J.Q. He, Z.Y. Pan, and C.H. Wang, Microstructure and Indentation Mechanical Properties of Plasma Sprayed Nano-bimodal and Conventional ZrO2-8 wt%Y2O3 Thermal Barrier Coatings, Vacuum, 2012, 86(8), p 1174-1185L.L. Shaw, D. Goberman, R. Ren, M. Gell, S. Jiang, Y. Wang, T.D. Xiao, and P.R. Strutt, The Dependency of Microstructure and Properties of Nanostructured Coatings on Plasma Spray Conditions, Surf. Coat. Technol., 2000, 130(1), p 1-8R.S. Lima, A. Kucuk, and C.C. Berndt, Bimodal Distribution of Mechanical Properties on Plasma Sprayed Nanostructured Partially Stabilized Zirconia, J. Mater. Sci. Eng. A, 2002, 327, p 224-232T. Wakui, J. Malzbender, and R.W. Steinbrech, Strain Dependent Stiffness of Plasma Sprayed Thermal Barrier Coatings, Surf. Coat. Technol., 2006, 200(16-17), p 4995-5002J. Malzbender and R.W. Steinbrech, Determination of the Stress-Dependent Stiffness of Plasma-Sprayed Thermal Barrier Coatings Using Depth-Sensitive Indentation, J. Mater. Res., 2003, 18(8), p 1975-198

Protein Oxidation Biomarkers and Myeloperoxidase Activation in Cerebrospinal Fluid in Childhood Bacterial Meningitis

The immunological response in bacterial meningitis (BM) causes the formation of reactive oxygen and nitrogen species (ROS, RNS) and activates myeloperoxidase (MPO), an inflammatory enzyme. Thus, structural oxidative and nitrosative damage to proteins and DNA occurs. We aimed to asses these events in the cerebrospinal fluid (CSF) of pediatric BM patients. Phenylalanine (Phe), para-tyrosine (p-Tyr), nucleoside 2'-deoxiguanosine (2dG), and biomarkers of ROS/RNS-induced protein and DNA oxidation: ortho-tyrosine (o-Tyr), 3-chlorotyrosine (3Cl-Tyr), 3-nitrotyrosine (3NO(2)-Tyr) and 8-oxo-2'-deoxyguanosine (8OHdG), concentrations were measured by liquid chromatography coupled to tandem mass spectrometry in the initial CSF of 79 children with BM and 10 without BM. All biomarkers, normalized with their corresponding precursors, showed higher median concentrations (p <0.0001) in BM compared with controls, except 8OHdG/2dG. The ratios o-Tyr/Phe, 3Cl-Tyr/p-Tyr and 3NO(2)-Tyr/p-Tyr were 570, 20 and 4.5 times as high, respectively. A significantly higher 3Cl-Tyr/p-Tyr ratio was found in BM caused by Streptococcus pneumoniae, than by Haemophilus influenzae type b, or Neisseria meningitidis (p = 0.002 for both). In conclusion, biomarkers indicating oxidative damage to proteins distinguished BM patients from non-BM, most clearly the o-Tyr/Phe ratio. The high 3Cl-Tyr/p-Tyr ratio in pneumococcal meningitis suggests robust inflammation because 3Cl-Tyr is a marker of MPO activation and, indirectly, of inflammation.Peer reviewe

Changes in capsular serotype alter the surface exposure of pneumococcal adhesins and impact virulence

We examined the contribution of serotype on Streptococcus pneumoniae adhesion and virulence during respiratory tract infection using a panel of isogenic TIGR4 (serotype 4) mutants expressing the capsule types 6A (+6A), 7F (+7F) and 23F (+23F) as well as a deleted and restored serotype 4 (+4) control strain. Immunoblots, bacterial capture assays with immobilized antibody, and measurement of mean fluorescent intensity by flow cytometry following incubation of bacteria with antibody, all determined that the surface accessibility, but not total protein levels, of the virulence determinants Pneumococcal surface protein A (PspA), Choline binding protein A (CbpA), and Pneumococcal serine-rich repeat protein (PsrP) changed with serotype. In vitro, bacterial adhesion to Detroit 562 pharyngeal or A549 lung epithelial cells was modestly but significantly altered for +6A, +7F and +23F. In a mouse model of nasopharyngeal colonization, the number of +6A, +7F, and +23F pneumococci in the nasopharynx was reduced 10 to 100-fold versus +4; notably, only mice challenged with +4 developed bacteremia. Intratracheal challenge of mice confirmed that capsule switch strains were highly attenuated for virulence. Compared to +4, the +6A, +7F, and +23F strains were rapidly cleared from the lungs and were not detected in the blood. In mice challenged intraperitoneally, a marked reduction in bacterial blood titers was observed for those challenged with +6A and +7F versus +4 and +23F was undetectable. These findings show that serotype impacts the accessibility of surface adhesins and, in particular, affects virulence within the respiratory tract. They highlight the complex interplay between capsule and protein virulence determinants