Periodontitis destructions are restored by synthetic glycosaminoglycan mimetic.

Periodontitis are bacterium-driven inflammatory diseases that destroy tooth-supporting tissues whose complete restoration is not currently possible. RGTA(R), a new class of agents, have this capacity in an animal model. Periodontitis was induced in hamsters and, starting 8 weeks later, injected RG1503, a glycosaminoglycan synthesized from a 40 kDa dextran behaving like a heparan sulfate mimetic (1.5 mg kg(-1) w(-1)) or saline for 8 weeks. The three periodontium compartments were evaluated by immunohistochemistry and morphometry. The gingival extracellular matrix disorganized by inflammation was restoring under treatment. The collagen network was repaired and resumed its previous organization. Fibrillin-1 expression was restored so that the elastic network rebuilt at a distance from the pocket and began to reconstruct near the pocket. Apoptotic cell numbers were decreased in the pocket epithelium, and more so in the infiltrated connective tissue. The continuity and the thickness of the basement membrane were restored and testified normalization of epithelium connective tissue interaction. The amount of alveolar bone increased around the first molar, and the interradicular bone was rebuilt. The root cementum was thickened and the number of proliferating cells in the periodontal ligament was increased close to the cementum. RG1503 treatment induces potent anabolic reactions in the extracellular matrices of the different tissues of the periodontium and recruitment of progenitors. In particular, the cell proliferation close to the root surface suggests the reformation of a functional attachment apparatus. These results demonstrate that RG1503 reverses the degenerative changes induced by inflammation and favors the conditions of a regenerative process. Thus, RGTA, a known matrix component mimetic and protector, may be considered as a new therapeutic tool to regenerate the tissues destroyed by periodontitis

Probing warm dense matter using femtosecond X-ray absorption spectroscopy with a laser-produced betatron source

Exploring and understanding ultrafast processes at the atomic level is a scientific challenge. Femtosecond X-ray absorption spectroscopy (XAS) arises as an essential experimental probing method, as it can simultaneously reveal both electronic and atomic structures, and thus potentially unravel their nonequilibrium dynamic interplay which is at the origin of most of the ultrafast mechanisms. However, despite considerable efforts, there is still no femtosecond X-ray source suitable for routine experiments. Here we show that betatron radiation from relativistic laser-plasma interaction combines ideal features for femtosecond XAS. It has been used to investigate the nonequilibrium dynamics of a copper sample brought at extreme conditions of temperature and pressure by a femtosecond laser pulse. We measured a rise-time of the electron temperature below 100 fs. This experiment demonstrates the great potential of the table-top betatron source which makes possible the investigation of unexplored ultrafast processes in manifold fields of research.Etude femtoseconde rayons X et optique de la dynamique ultrarapide de photocommutation de matériaux moléculaires magnétiquesFifth Generation of Ultra Bright X Ray Bea

Ptychographic measurements of ultrahigh-intensity laser–plasma interactions

International audienceThe extreme intensities now delivered by femtosecond lasers make it possible to drive and control relativistic motion of charged particles with light1, opening a path to compact particle accelerators2, 3 and coherent X-ray sources4, 5. Accurately characterizing the dynamics of ultrahigh-intensity laser–plasma interactions as well as the resulting light and particle emissions is an essential step towards such achievements. This remains a considerable challenge, as the relevant scales typically range from picoseconds to attoseconds in time, and from micrometres to nanometres in space. In these experiments, owing to the extreme prevalent physical conditions, measurements can be performed only at macroscopic distances from the targets, yielding only partial information at these microscopic scales. This letter presents a major advance by applying the concepts of ptychography6, 7 to such measurements, and thus retrieving microscopic information hardly accessible until now. This paves the way to a general approach for the metrology of extreme laser–plasma interactions on very small spatial and temporal scales