Thermodynamics of small systems by nanocalorimetry: from physical to biological nano-objects

Membrane based nanocalorimeters have been developed for ac calorimetry experiments. It has allowed highly sensitive measurements of heat capacity from solid state physics to complex systems like polymers and proteins. In this article we review what has been developed in ac calorimetry toward the measurement of very small systems. Firstly, at low temperature ac calorimetry using silicon membrane permits the measurement of superconducting sample having geometry down to the nanometer scale. New phase transitions have been found in these nanosystems illustrated by heat capacity jumps versus the applied magnetic field. Secondly, a sensor based on ultra-thin polymer membrane will be presented. It has been devoted to thermal measurements of nanomagnetic systems at intermediate temperature (20K to 300K). Thirdly, three specific polyimide membrane based sensors have been designed for room temperature measurements. One is devoted to phase transitions detection in polymer, the second one to protein folding/unfolding studies and the third one will be used for the study of heat release in living cells. The possibility of measuring systems out of equilibrium will be emphasized

A New Biocontrol Tool to Fight Potato Late Blight Based on Willaertia magna C2c Maky Lysate

Potato late blight (PLB) is one of the most destructive disease affecting potatoes. Late blight control relies almost exclusively on the use of chemical pesticides, including copper products, which are efficient but controversial due to their environmental toxicity. Societal pressure and the quest for more sustainable agriculture reinforce the need for natural plant protection products. To respond to this demand, we tested the lysate of the amoeba Willaertia magna C2c Maky on PLB. This active substance exhibits plant protection properties against grape downy mildew thanks to a dual mode of action (plant elicitor and antifungal direct effect). We hypothesized that this active substance might also have an effect against other diseases caused by oomycetes on other crops, such as potato. In vitro, in planta, and in-field studies were conducted. The collected data demonstrate that the lysate of the amoeba Willaertia magna C2c Maky is able to elicit potato defenses, and direct fungicidal activity against Phytophtora infestans was observed. Proof of efficacy was first obtained in greenhouse, with up to 80% disease reduction, and confirmed in field trials. Formulated products provided up to 77% protection in field in the case of low infestation (28%) and up to 49% protection when the untreated plants were 100% destroyed. Willaertia magna C2c Maky was also able to significantly increase yield by up to 30% in field trials

A New Active Substance Derived from Lyzed Willaertia magna C2c Maky Cells to Fight Grapevine Downy Mildew

Downy mildew of grapevine is one of the most destructive grapevine diseases worldwide. Nowadays, downy mildew control relies almost exclusively on the use of chemical pesticides, including copper products, which are efficient but controversial due to their environmental toxicity. Natural plant protection products have become important solutions in the quest for the sustainable production of food and pest management. However, most biocontrol agents currently on the market, such as biofungicides or elicitors, have a limited efficacy; thus, they cannot replace chemical compounds in full. Our innovation is a natural active substance, which is a lysate of the amoeba Willaertia magna C2c Maky. This active substance is not only able to elicit grapevine defenses, but it also demonstrates direct fungicidal activity against Plasmopara viticola. The efficacy of this new natural substance was demonstrated both in a greenhouse and in a field. The amoeba lysate provided up to 77% protection to grapevine bunches in the field in a natural and safe way

Cadre de vie, équipement, santé dans les sociétés méditerranéennes

L’antiquité gréco-romaine a voulu mettre en harmonie les outils de la vie quotidienne et le bon fonctionnement du corps humain : les réflexions d’Hippocrate sur l’art urbain aboutissent de la sorte à des seuils de rationalité pour le peuplement des villes. Au Moyen Âge, une police des ressources apparaît dans les différentes communautés : les municipalités urbaines militent pour la pureté des eaux, tandis que les collectivités montagnardes s’approprient des territoires où toutes les subsistances coutumières sont disponibles. Avec l’élan démographique des époques modernes et contemporaines, la manière de penser le cadre de vie est globalisée : les pestes du xviiesiècle, les disettes régionales du xviiiesiècle, le choléra du xixesiècle, tous ces fléaux poussent à la médicalisation étatique de la vie matérielle, qu’il s’agisse de la nourriture, de l’hygiène ou des remèdes. D’ailleurs, dans la France de 1900, le corps médical est devenu un récepteur de considération politique. En montrant comment la prévention du malheur est progressivement devenue une affaire d’état, après avoir nourri les morales communautaires, le présent volume analyse les discours qui ont pris une option sur l’organisation du quotidien. Il les examine à travers leurs origines, leurs évolutions, leurs contradictions et leurs réalisations

Evaluation of intraosteoblastic activity of dalbavancin against Staphylococcus aureus in an ex vivo model of bone cell infection

International audienceAbstract Objectives Long-acting lipoglycopeptides are promising therapeutic options in Staphylococcus aureus bone and joint infections (BJIs). This study evaluated the ability of dalbavancin to eradicate the intraosteoblastic reservoir of S. aureus, associated with BJI chronicity. Methods Osteoblastic cells were infected with a standardized inoculum of the S. aureus reference strain HG001 and incubated for 24 h with dalbavancin, vancomycin or rifampicin using the MIC, 10×MIC, 100×MIC and/or the intraosseous concentrations reached using standard therapeutic doses (i.e. vancomycin, 10 mg/L; rifampicin, 2 mg/L; and dalbavancin, 6 mg/L). The remaining intracellular bacteria were quantified by plating cell lysates. Results MICs of dalbavancin, vancomycin and rifampicin were 0.125, 1 and 0.004 mg/L, respectively. Dalbavancin significantly reduced the intracellular inoculum of S. aureus starting at a concentration equal to the MIC, with a significant dose effect, ranging from a reduction of 31.4% (95% CI = 17.6%–45.2%) at MIC to 51.6% (95% CI = 39.8%–63.4%) at 100×MIC compared with untreated cells. Of note, dalbavancin was the only molecule to significantly reduce the intraosteoblastic inoculum at low concentration (MIC). At intraosseous concentrations, dalbavancin reduced the intracellular inoculum by 49.6% (95% CI = 45.1%–54.1%) compared with untreated cells (P < 0.001), with no significant difference compared with vancomycin (38.1%; 95% CI = 19.2%–57.0%; P = 0.646), and was less efficient than rifampicin (69.0%; 95% CI = 63.2-74.8; P < 0.001). Conclusions Dalbavancin was able to decrease the intraosteoblastic S. aureus inoculum by 50% at intraosseous concentrations reached during standard human therapeutic dosing, with no difference compared with vancomycin, and remained less efficient than rifampicin. However, it was the only molecule significantly active at low concentration