COVID-19 et transplantation d’organes, les leçons du recensement national de la Société francophone de transplantation

International audienceThe Covid-19 pandemic hit the transplant world in March 2020. Teams quickly organized themselves to optimize the management of their immunocompromised patients and to progress in the knowledge of this new disease. To do this, a French Registry was set up, listing all solid organ transplant patients who had developed a SARS Cov2 infection. Numerous studies carried out on the basis of these data have enabled us to describe the disease in transplant patients, to characterize its clinical and biological severity factors and to define its prognosis. The mortality of transplant patients hospitalized for Covid-19 is 23% at 60 days and renal insufficiency plays a major role in the poor prognosis in addition to the classic risk factors described in the general population. The advent of vaccination has been a great relief, but transplant patients have developed a poorer vaccine response than immunocompetent subjects, keeping them at risk of severe disease after an adapted vaccination schedule. Specific strategies had to be adopted in this particularly fragile population (increased number of vaccine doses, injection of monoclonal antibodies). The collaboration of the French transplantation centers under the impulse of the Société Francophone de Transplantation allowed us to carry out many collaborative projects, which were of great use for the care of the patients

Structure and properties of oxidatively stabilized viscose rayon fibers impregnated with boric acid and phosphoric acid prior to carbonization and activation steps

The role of boric acid-phosphoric acid (BA-PA) impregnation and oxidation on the structure and properties of viscose rayon fibers was examined in air at temperatures ranging from 150 to 250 A degrees C. The results obtained from the measurements of fiber thickness, linear density, X-ray diffraction, thermal analysis (DSC and TGA), and infrared spectroscopy demonstrated that oxidation temperature had a significant influence on the structure and properties of oxidized viscose rayon fibers. Physical transformations were characterized by fiber thickness and linear density values together with color variations and improved burning behavior with progressing oxidation temperature. The DSC analysis showed that BA-PA impregnation enhanced thermal stability and prevented the evolution of volatile by-products by blocking the primary hydroxyl groups. TGA thermograms revealed an enhancement in the char yields. X-ray diffraction analysis showed the loss of cellulose II crystalline structure caused by the decrystallization process initiated by the gradual loss of intermolecular hydrogen bonds. Analysis of IR spectra revealed gradual and continuous loss of intramolecular and intermolecular hydrogen bonding as part of the simultaneously occurring dehydrogenation and dehydration reactions. Analysis of IR data also demonstrated the disturbance of the cellulose II crystalline structure with increasing oxidation temperature in agreement with the results obtained from X-ray diffraction measurements. The formation of C=C bonds attributed to the crosslinked ladder-like structure was also confirmed by the IR spectra.The role of boric acid–phosphoric acid (BA–PA) impregnation and oxidation on the structure and properties of viscose rayon fibers was examined in air at temperatures ranging from 150 to 250 C. The results obtained from the measurements of fiber thickness, lineardensity, X-ray diffraction, thermal analysis (DSC and TGA), and infrared spectroscopy demonstrated that oxidation temperature had a significant influence on the structure and properties of oxidized viscose rayon fibers. Physical transformations were characterized by fiber thickness and linear density values together with color variations and improved burning behavior with progressing oxidation temperature. The DSC analysis showed that BA–PA impregnation enhanced thermal stability and prevented the evolution of volatile by-products by blocking the primary hydroxyl groups. TGA thermograms revealed an enhancement in the char yields. X-ray diffraction analysis showed the loss of cellulose II crystalline structure caused by the decrystallization process initiated by the gradual lossof intermolecular hydrogen bonds. Analysis of IR spectra revealed gradual and continuous loss of intramolecular and intermolecular hydrogen bonding as part of the simultaneouslyoccurring dehydrogenation and dehydration reactions.Analysis of IR data also demonstrated the disturbance of the cellulose II crystalline structure with increasing oxidation temperature in agreement with the results obtained from X-ray diffraction measurements. The formation of C=C bonds attributed to the crosslinked ladder-like structure was also confirmed by the IR spectra