Floridoside Extracted from the Red Alga Mastocarpus stellatus Is a Potent Activator of the Classical Complement Pathway

Many biological properties of algae have been found to have useful applications in human health, particularly in the fields of oncology and immunology. Floridoside, extracted from the red alga Mastocarpus stellatus, has a structure similar to the xenoantigen Gal alpha 1–3 Gal. This xenoantigen has been described to induce a high immune response in human xenografts and is mediated by natural anti-gal antibodies that activate the classical complement pathway. Based on this property, we analyzed the potential activities of floridoside on the immune system. We demonstrated that floridoside activates a complement cascade via the classical complement pathway, through the recruitment and activation of natural IgM. This algal molecule could represent an important step in the development of a potent new anticomplementary agent for use in therapeutic complement depletion

Complement dependent cytotoxicity activity of therapeutic antibody fragments is acquired by immunogenic glycan coupling

Abstract Oligosaccharides are implicated in the development of the immune response notably in complement activation. Anti-tumoural immunotherapy by monoclonal antibodies (mAbs) offers some advantages to chemotherapy including cell targeting but some of them are inefficient to generate cytotoxicity dependent complement (CDC) known to be important in the antibody\u2019s efficacy. The aim of this study is to give a CDC activity of mAb by linkage of a complement activating oligosaccharide to this antibody via a hetero-bifunctional linker allowing control of the conjugation reaction. We worked on non Hodgkin Burkitt\u2019s lymphoma as cancer source, Fab fragments of rituximab devoid of complement activity as mAb and the trisaccharide Gal\u3b1(1\u21923)Gal\u3b2(1\u21924)GlcNAc as immunogenic glycan. The bioconjugate Fab-Gal was characterized by biochemical methods and we demonstrated that the \u3b1-Gal epitope was recognized by seric immunoglobulins. After checking the recognition capacity of the Fab- Gal conjugate for the CD20 epitope, in vitro assays were performed to evaluate the activation of the complement cascade by the Fab-Gal conjugate. The effect of this bioconjugate was confirmed by the evaluation of the proliferation response of Burkitt\u2019s cell line. The relative facility realization of this strategy represents new approaches to increase activities of mAbs

Reuse of medical face masks in domestic and community settings without sacrificing safety: Ecological and economical lessons from the Covid-19 pandemic

The need for personal protective equipment increased exponentially in response to the Covid-19 pandemic. To cope with the mask shortage during springtime 2020, a French consortium was created to find ways to reuse medical and respiratory masks in healthcare departments. The consortium addressed the complex context of the balance between cleaning medical masks in a way that maintains their safety and functionality for reuse, with the environmental advantage to manage medical disposable waste despite the current mask designation as single-use by the regulatory frameworks. We report a Workflow that provides a quantitative basis to determine the safety and efficacy of a medical mask that is decontaminated for reuse. The type IIR polypropylene medical masks can be washed up to 10 times, washed 5 times and autoclaved 5 times, or washed then sterilized with radiations or ethylene oxide, without any degradation of their filtration or breathability properties. There is loss of the antiprojection properties. The Workflow rendered the medical masks to comply to the AFNOR S76-001 standard as “type 1 non-sanitory usage masks”. This qualification gives a legal status to the Workflow-treated masks and allows recommendation for the reuse of washed medical masks by the general population, with the significant public health advantage of providing better protection than cloth-tissue masks. Additionally, such a legal status provides a basis to perform a clinical trial to test the masks in real conditions, with full compliance with EN 14683 norm, for collective reuse. The rational reuse of medical mask and their end-of-life management is critical, particularly in pandemic periods when decisive turns can be taken. The reuse of masks in the general population, in industries, or in hospitals (but not for surgery) has significant advantages for the management of waste without degrading the safety of individuals wearing reused masks

Écologie des Vibrio spp. en Manche-Mer du Nord (diversité et occurrence de souches potentiellement pathogènes pour l'homme et les animaux, et déterminisme des paramètres environnementaux sur l'abondance des Vibrio spp.)

Plus de 130 espèces de Vibrio, bactéries ubiquitaires des milieux marins et estuariens sont décrites, dont certaines sont des pathogènes d organismes marins (poissons, coraux, coquillages, ). Douze espèces sont pathogènes pour l homme, parmi lesquelles V. cholerae, V. parahaemolyticus et V. vulnificus. Les cas d infections humaines sont essentiellement liés à la consommation de produits de la mer crus ou à l exposition de plaies cutanées à l eau de mer. En France, ce risque est faible mais pourrait s accentuer en raison de la consommation croissante de produits de la mer, de l'augmentation de la part des individus immunodéprimés dans la population, de l'impact des activités anthropiques et du réchauffement climatique sur le milieu marin. Une meilleure compréhension de l'écologie de ces bactéries (distribution, abondance et diversité) est un pré-requis à la mise en place d une surveillance environnementale de ce risque. L étude menée au cours de ma thèse en zone Manche-Mer du Nord, dans le cadre du programme Vibrio Manche (2009-2012, partenariat EDFR&D/Ifremer/Institut Pasteur de Lille), avait pour objectif d'évaluer la diversité et la distribution spatio-temporelle côtière des vibrions, dont des espèces potentiellement pathogènes pour l homme et les animaux, et leur relation avec les paramètres environnementaux biologiques (phytoplancton et zooplancton) et physico-chimiques. La stratégie de suivi a reposé sur le dénombrement et l isolement de souches de Vibrio, à 22C et 37C sur milieu sélectif, à partir d eau de mer et de sédiments superficiels collectés au cours de neuf campagnes d échantillonnage et associés à la mesure de paramètres environnementaux. Le développement et la validation d outils d identification des souches environnementales par PCR en temps réel et le séquençage de marqueurs génétiques discriminants ont conduit à mettre en évidence une grande diversité d espèces parmi les isolats à 22C, celle-ci étant composée principalement de pathogènes d organismes marins dont l espèce V. splendidus. Les isolats à 37C, marqués par la prédominance de deux espèces, V. alginolyticus et V. harveyi, et la rareté des pathogènes humains détectés dans les conditions d analyses retenues pour cette étude. Au terme de l étude, nous avons mis en évidence la présence de 20 et 17 espèces de vibrions respectivement à 22C (deux campagnes) et 37C (neuf campagnes) sur la zone étudiée, et l influence probable de conditions environnementales contrastées sur la structure de ces populations. En termes d abondance, les vibrions cultivables à 37C ont montré une forte saisonnalité, et une relation significative à la température de l eau et à l abondance totale du zooplancton. La saisonnalité des vibrions cultivables à 22C a été moindre, et leur abondance a pu être reliée de façon significative à la concentration en chlorophylle a totale et également à l abondance totale en zooplancton. Ces éléments de connaissance et la stratégie d identification développée pourront, à terme, contribuer au développement d outils de surveillance microbiologique environnementale et ouvrent des perspectives pour mieux comprendre l écologie des vibrions et les facteurs structurant non seulement leur abondance, mais aussi leur diversité.One hundred and thirty species of vibrios, ubiquitous bacteria of marine and estuarine environments have been described, some of them being pathogenic for marine organisms. Twelve species are classified as human pathogens, Vibrio cholerae, V. parahaemolyticus and V. vulnificus being the most frequently reported in cases of infection. Human infections are linked mostly to raw seafood consumption or to the exposure of skin wounds to contaminated seawater. In France, the risk is low but it is expected to increase in the future due to the increase of raw seafood consumption, the part of immuno-compromised people, but also the impact of anthropic activities and global warming on the marine environment. A better understanding of the ecology of these bacteria (distribution pattern, abundance and diversity) is a prerequisite for the monitoring of the Vibrio-risk in the environment. The 2-year study carried out in the Eastern English Channel during my PhD was part of the Vibrio Manche program (2009-2012, funding EDF R&D/Ifremer/Institut Pasteur de Lille), which main objective was to characterize the spatio-temporal distribution of the vibrios, among which the potentially pathogenic species for human and animal, and their relations with the biotic(phytoplankton and zooplankton) and abiotic environmental parameters. The strategy consisted in the enumeration and isolation of Vibrio strains, at 22C and37C on a selective medium, from seawater and superficial sediments collected during nine sampling campaigns and associated with the recording of environmental parameters. The protocol developed in this study provides an appropriate and rapid screening tool to identify a large number of bacterial strains routinely isolated from the environment. This was based on real-time PCR assays and the sequencing of discriminant genetic markers. We highlighted the important diversity of species among the 22C isolates, represented mainly by species pathogenic for marine organisms such as V. splendidus. Contrastingly, the 37C isolates were mainly represented by two species, V. alginolyticus and V. harveyi, and the potentially pathogenic species for humans were rarely detected using this experimental approach. We detected 20 and 17 species of vibrios among the 22C (two sampling campaigns) and 37C(nine sampling campaigns) isolates, respectively, and highlighted the probable influence of contrasted environmental conditions on these populations structure. These two populations presented different seasonal dynamics, as the seawater temperature and the zooplankton abundance showed to be the main drivers for the 37C population. The 22C population seemed to be linked to the chlorophyll a concentration and zooplankton abundance. These data and the approach developed in this study could contribute to the development of tools for the monitoring of coastal environment and they give perspectives to better understand the ecology of the vibrios and the environmental factors driving their abundance and diversity.BREST-SCD-Bib. electronique (290199901) / SudocSudocFranceF

Contact AFM on soft surfaces: Elasticity and friction effects

We present contact AFM images of an annealed film of latex balls of 5° glass transition temperature. Surface appears to be constituted of an hexagonal arrangement of flatten spheres. Contrast is seen to depend very much on the applied load and on the scan direction: spheres appear concave or convex according to these parameters. An analysis of the friction clearly shows that there are two regimes for imaging. For high magnifications, the tip is deeply intruded in the material and images do not reflect the topography of the surface but seem to be characteristic of its mechanical properties. For higher scan domains, friction is of classical type and resolution is good. These results permit to clarify the limitations of the technique applied on soft materials.Nous montrons des images obtenues en AFM de contact d'un film recuit de billes de latex de 5° de température de transition vitreuse. La surface présente un arrangement hexagonal de sphères aplaties. Le contraste dépend fortement de la force appliquée et de la direction de balayage : les sphères apparaissent soit concaves soit convexes. Une analyse des frottements montre distinctement deux régimes de fonctionnement du microscope. Pour de forts grossissements, la pointe est profondément enfoncée dans le matériau et les images ne reflètent pas la topographie de la surface, mais semblent caractéristiques de ses propriétés mécaniques. Pour de plus grands domaines de balayage, le frottement est de type classique et la résolution est bonne. Ces résultats permettent de préciser les limitations de la technique pour des matériaux mous

Multi-step purification method of water-soluble oligosaccharides produced from hardwood and softwood

International audienceAbstract Pressurized hot water pretreatment was performed on softwood (SW) and hardwood (HW) chips following the same conditions (1 h at 170 °C) in order to partly hydrolyse hemicelluloses. The complete characterization of these sugar enriched autohydrolysates (AH) being rather complex, two different purification methods were conducted. Nanofiltration (NF) 1kDa membrane and ultrafiltration (UF) 3 and 5kDa membranes were used to separate oligosaccharides (OS) from undesired compounds and for their molar mass fractionation. Granulated activated charcoal (GAC) adsorption was also used for hydrolysates detoxification. The chemical nature of OS and side charge groups vary significantly depending of the fractions obtained, e. g. xylans' chain length is positively correlated with the degree of acetylation. UF at 5kDa allows for the total separation of galactoglucomannans (GGMs) from xylans, in SW AH, however, this result was not achieved with HW. From the acid soluble lignin (ASL) removal point of view, membrane filtration from 1kDa is more efficient than activated carbon treatment concerning HW AH, on the contrary to SW AH. Regarding the lignin to OS ratio, for both species, GAC leads to a better sugar purity

Production of hemicellulose oligomers from softwood chips using autohydrolysis followed by an enzymatic post-hydrolysis

International audienceAbstract In the context of value added valorization of hemicelluloses (HCs), their soft extraction by autohydrolysis (AH) of softwood (SW) chips has been optimized via the temperature/time parameters (170°C/2 h, 170°C/1 h and 150°C/1 h). Two enzyme mixtures containing mainly a glucanase and a mannanase were used to decrease the degree of polymerization (DP) of the extracted HCs. Hydrolysates containing HCs were analyzed in terms of monomers and oligomers, molecular weight distribution (MWD) and chemical composition. The MW was strongly dependent on AH conditions: most of the water-soluble HCs with 1800 Da MW were obtained at 150°C/1 h. The parameters 170°C/2 h gave rise to MWs<1800 Da. Enzymatic hydrolysis (EH) reduced efficiently the DP of HCs, and the glucosidase was more efficient than the mannanase, but the former also hydrolyzed more oligomers into their monomeric components

Production of hemicellulose oligomers from softwood chips using autohydrolysis followed by an enzymatic post-hydrolysis

International audienceAbstract In the context of value added valorization of hemicelluloses (HCs), their soft extraction by autohydrolysis (AH) of softwood (SW) chips has been optimized via the temperature/time parameters (170°C/2 h, 170°C/1 h and 150°C/1 h). Two enzyme mixtures containing mainly a glucanase and a mannanase were used to decrease the degree of polymerization (DP) of the extracted HCs. Hydrolysates containing HCs were analyzed in terms of monomers and oligomers, molecular weight distribution (MWD) and chemical composition. The MW was strongly dependent on AH conditions: most of the water-soluble HCs with 1800 Da MW were obtained at 150°C/1 h. The parameters 170°C/2 h gave rise to MWs<1800 Da. Enzymatic hydrolysis (EH) reduced efficiently the DP of HCs, and the glucosidase was more efficient than the mannanase, but the former also hydrolyzed more oligomers into their monomeric components