Utilisation des algues dans les compléments alimentaires : usages et justifications scientifiques

Thèse proposée pour un prix de thèse.L’usage des compléments alimentaires progresse continuellement en France. De ce marché, les officines représentent le principal canal de distribution. Parmi les produits proposés, l’usage des plantes permet aux laboratoires d’avoir une offre très large pour les consommateurs qui souhaitent utiliser des produits d’origine naturelle. Ce travail propose de connaitre plus particulièrement le cas des algues, catégorie de plantes que l’on recense dans près de cent références de compléments alimentaires vendus en pharmacie. Dans un premier temps sera expliquée la réglementation des compléments alimentaires. Suivra une description du monde des algues et des différents usages de celles-ci. Ensuite, une étude de sept d’entre elles (Undaria pinnatifida, Ascophyllum nodosum, Fucus vesiculosus, Phymatolithon calcareum, Porhyra umbilicalis, Chlorella vulgaris et Spirulina spp.) recensera leurs usages en tant que compléments alimentaires ainsi que leurs propriétés en santé. Enfin, une synthèse sous forme de tableau détaillera les cas des autres algues utilisables dans les compléments alimentaires, mais peu sollicitées actuellement

Insight in the burning behavior of aluminum nanopowders

Nanomaterials are innovative materials and they sometimes show unexpected behavior that could impact the determination of their safety parameters. In this work, aluminum nanopowder (40 – 60 nm) burning behavior was investigating by considering the influence of coating, preheating as well as the preparation procedure. These tests were performed in the INERIS SNANO platform dedicated to the evaluation of flammability and explosivity of nanopowders. They were focused on the evaluation of the reactivity and the ignition sensitivity of the nanopowder to hot surfaces which constitute one of the main sources of ignition of combustible materials. Once a hot surface has raised the temperature of a portion of powder to its ignition temperature, combustion reaction then self-propagates. DSC/TGA tests were performed to characterize both the reactivity of the samples and determine the oxide layer thickness of the particles, which has a direct influence on the thermokinetics parameters of aluminum. These results were put in perspective with available data in the literature to highlight the unique reactivity of this product whose particle size distribution is close of the theoretical critical diameter inducing pyrophoricity of aluminum. Layer ignition tests were also performed so that a deposit a dust layer of given size and thickness on a horizontal circular plate was heated to predetermined temperatures until a critical temperature for ignition is reached. Temperature values were ranging between 200 and 450°C. No ignition was observed however the dust layer showed a great ignition sensitivity to burning metal particles (sparks) and a differentiated burning behavior depending on the initial temperature of the powder. It is shown that the initial temperature of the powder has a marked influence on the burning class of the nanopowder as confirmed through VDI 2263-1 combustibility tests: at low temperature (400°C), aluminum burns actively with bright light emission of the burning zone. This type of behavior, which has been observed in the past for some microsized powders (Bartknecht, 1989) may have direct implication on the management of fire risks related to deposits of metallic nanopowders and special attention should be paid on the potential misuse of such test results to implement safety barriers (Agnes, 2018)

Some considerations when evaluating physico-chemical hazards of nanopowders

The regulatory classification of the physico-chemical hazards of powders is defined in two references, which describe the test methods to be applied, as well as the criteria and the classification thresholds. These two references are respectively the European CLP Regulation and the transport of dangerous goods UN regulation. These two reference systems enable to associate identified hazards with safety rules related to the handling, storage and production of the powders. Traditional microscale powders as well as innovative materials like nanopowders or very fluffy materials need to follow these classification rules. Typically, the properties of interest for nanopowders are related to the reactivity with air and water. The related hazards are defined by the CLP regulation in the following classes: flammability, pyrophoricity, self-heating, water reactivity and oxidizing capability. The hazardous properties of nanopowders can a priori be routinely determined with the regulatory experimental tests performed in an adequate platform like S-NANO at INERIS. However, several aspects were overlooked so far for innovative materials that show specific properties like very low density and high specific surface area. This presentation deals with a review of the limitations of the current tests as well as detailed considerations related to some tests (powder segregation issues, specific ignition issues, safety issues for the operators…). These aspects could perhaps be not thoroughly considered for microscale powders but in the case of nanopowders, these parameters are shown to be of importance in order to evaluate physico-chemical hazards. It is then of primary importance to assess carefully these new behaviors in order to prevent the production of misleading information in safety data sheets

Protocol for the e-POWUS Project: multicentre blinded-randomised controlled trial of ultrasound speed choice to improve sonography quality in pregnant women with obesity

International audienceIntroduction During pregnancy, maternal obesity increases the risk of fetal abnormalities. Despite advances in ultrasound imaging, the assessment of fetal anatomy is less thorough among these women. Currently, the construction of ultrasound images uses a conventional ultrasound propagation velocity (1540 m/s), which does not correspond to the slower speed of propagation in fat tissue. The main objective of this randomised study is to compare the completeness of fetal ultrasonography according to whether the operator could choose the ultrasound velocity (1420, 1480 or 1540 m/s) or was required to apply the 1540 m/s velocity. Methods and analysis This randomised trial is an impact study to compare a diagnostic innovation with the reference technique. The trial inclusion criteria require that a pregnant woman with obesity be undergoing a fetal morphology examination by ultrasound from 20 +0 to 25 +0 gestational weeks. Randomisation will allocate women into two groups. The first will be the ‘modulable speed’ group, in which operators can choose the speed of ultrasound propagation to be considered for the morphological analysis: 1420, 1480 or 1540 m/s. In the second ‘conventional speed’ group, operators will perform the morphological examination with the ultrasound speed fixed at 1540 m/s. The adjudication committee, two independent experts, will validate the completeness of each examination and the quality of the images. Ethics and dissemination This research protocol does not change the standard management. The only possible impact is an improvement of the ultrasound examination by improving the quality of the image and the completeness of morphological examination. The Agence du Médicament et produits de santé approved this study (2018-A03478-47). The anonymised data will be available on request from the principal investigator. Results will be reported in peer-reviewed journals and at scientific meetings. Trial registration number ClinicalTrials.gov ( http://www.clinicaltrials.gov ) Registry ( NCT04212234 )

SARS-CoV-2 T-cell responses after one or two COVID-19 vaccine boosters in allogeneic transplant recipients

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Strong SARS-CoV-2 T-Cell Responses after One or Two COVID-19 Vaccine Boosters in Allogeneic Hematopoietic Stem Cell Recipients

International audienceA full exploration of immune responses is deserved after anti-SARS-CoV-2 vaccination and boosters, especially in the context of allogeneic hematopoietic stem cell transplantation (allo-HSCT). Although several reports indicate successful humoral responses in such patients, the literature is scarce on cellular specific immunity. Here, both B- (antibodies) and T-cell responses were explored after one (V3 n = 40) or two (V4 n = 12) BNT162b2 mRNA vaccine boosters in 52 allo-HSCT recipients at a median of 755 days post-transplant (250 BAU/mL) and anti-spike T-cell responses. Similarly, 81% of the patients developed protective antibody levels, without difference between V3 and V4 (82.5% vs. 75%, p = 0.63), and 85% displayed T-cell responses. The median frequency of anti-spike T cells did not differ either between controls or the whole cohort of patients, although it was significantly lower for V3 (but not V4) patients. COVID-19 infections were solely observed in individuals having received only one booster. These results indicate that four vaccine injections help to achieve a satisfactory level of both humoral and cellular immune protection in allo-HSCT patients

SARS-CoV-2 T-cell responses in allogeneic hematopoietic stem cell recipients following two doses of BNT162b2 vaccine.

International audienceVirus-specific humoral and cellular immunity act synergistically to protect the host from viral infection. In our recent prospective monocentric study of 117 hematopoietic stem cell adult recipients, we found that 54% and 83 % achieved a humoral response after a first and a second vaccine dose of BNT162b2 anti-SARS-CoV-2 messenger RNA respectively. In this study, we evaluated the T-cell response against the SARS-CoV-2 spike protein after two doses of vaccine in a cohort of patients allografted (N=46) for acute myeloblastic leukemia (AML, N=27) or myelodysplastic syndrome (MDS, N=19) (Table 1) and 16 healthy controls. For the 18 patients for whom we detected the highest frequencies of anti-spike CD3+ T cells, we evaluated the anti-spike responses of CD4+ and CD8+ T-cell populations as well as their functionality by testing the production of IFN-γ and TNF-α by flow cytometry

SARS-CoV-2 T-Cell Responses in Allogeneic Hematopoietic Stem Cell Recipients following Two Doses of BNT162b2 mRNA Vaccine

International audienceBackground: At variance to humoral responses, cellular immunity after anti-SARS-CoV-2 vaccines has been poorly explored in recipients of allogeneic hematopoietic stem-cell transplantation (Allo-HSCT), especially within the first post-transplant years where immunosuppression is more profound and harmful. Methods: SARS-CoV-2 Spike protein-specific T-cell responses were explored after two doses of BNT162b2 mRNA vaccine in 45 Allo-HSCT recipients with a median time from transplant of less than 2 years by using INF-γ ELISPOT assay and flow-cytometry enumeration of CD4+ and CD8+ T lymphocytes with intracellular cytokine production of IFN-γ and TNF-α. Results: A strong TNF-α+ response from SARS-CoV-2-specific CD4+ T-cells was detected in a majority of humoral responders (89%) as well as in a consistent population of non-humoral responders (40%). Conclusions: T-cells are likely to participate in protection against COVID-19 viral infection, even in the absence of detectable antibody response, especially in the first years post-transplant in Allo- HSCT recipients

Increase over time of antibody levels 3 months after a booster dose as an indication of better protection against Omicron infection

International audienceThe third, "booster", vaccination increases the overall immune response against SARS-CoV-2 variants. However, after the initial peak at around 3 weeks post-vaccination, anti-spike antibody levels decline. Post-booster kinetics of cellular response has been less investigated and there is no documented evidence of a true boosting effect. Furthermore, multiple studies underline the less effective immune responses against Omicron, the latest variant of concern, at both humoral and cellular levels. In this letter, we analyse humoral (anti-RBD IgG levels) and cellular (IFN-? release assay) immune response in 205 health care workers 3 weeks and 3 months after administration of an mRNA-based booster dose, either mRNA-1273 or BNT162b2. Since all subjects were SARS-CoV-2 infection-naive, we also looked at the incidence of Omicron infection between 3 and 6 months post-booster.At both timepoints, 3x mRNA-1273 vaccination had the highest overall antibody and IFN-? levels, followed by 3x BNT162b2 vaccination and heterologous mRNA-based regimens. Heterologous ChAdOx1-mRNA-based regimen had the lowest antibody levels while cellular response equal to that of 3x BNT162b2 vaccination and heterologous mRNA-based regimens. Our results show that both humoral and cellular responses waned at 3 months for all vaccination regimens. However, we identified three trajectories of dosage variation. Interestingly, the subgroup of subjects with increasing anti-RBD IgG levels over time had a lower incidence of Omicron infection. Whether increasing humoral response at 3 months post-booster is more indicative of protection than a high initial peak remains to be confirmed in a larger cohort

Decline of Humoral and Cellular Immune Responses Against SARS-CoV-2 6 Months After Full BNT162b2 Vaccination in Hospital Healthcare Workers

International audienceClinical trials and real-world evidence on COVID-19 vaccines have shown their effectiveness against severe disease and death but the durability of protection remains unknown. We analysed the humoral and T-cell immune responses in 110 healthcare workers (HCWs) vaccinated according to the manufacturer’s recommended schedule of dose 2 three weeks after dose 1 from a prospective on-going cohort in early 2021, 3 and 6 months after full vaccination with the BNT162b2 mRNA vaccine. Anti-RBD IgG titres were lower in HCWs over 60 years old 3 months after the second dose (p=0.03) and declined in all the subjects between 3 and 6 months with a median percentage change of -58.5%, irrespective of age and baseline comorbidities. Specific T-cell response measured by IGRA declined over time by at least 42% (median) in 91 HCWs and increased by 33% (median) in 17 others. Six HCWs had a negative T-cell response at 6 months. Ongoing follow-up should provide correlates of long-term protection according to the different immune response profiles observed. COVIDIM study was registered under the number NCT04896788 on clinicaltrials.gov