Polyelectrolyte complexes via desalting mixtures of hyaluronic acid and chitosan-Physicochemical study and structural analysis.

Polyelectrolyte complexes (PECs) were prepared from Chitosan (CS) and Hyaluronic Acid (HYA) homogeneous mixtures of aqueous solutions. The method consisted of preparing a homogeneous mixture of the two polysaccharides via charge screening at high salt concentrations. Then, the mixture was dialyzed, leading to the controlled self-assembly of the two polyelectrolytes. Critical parameters like the chitosan degree of acetylation (DA) and molar mass (Mw), the residual salt concentration and the molar charge ratio r=nNH3(+) (CS)/nCOO(-) (HYA) accounted for the transition from homogeneous aqueous solutions to colloidal suspensions (r=0.1) or gel coacervates (r=0.5). The influence of the DA and Mw of CS was evaluated by visual observations, light scattering and rheological measurements. For low values of r, Small Angle X-ray Scattering (SAXS) experiments revealed that the HYA nanostructure was weakly affected by the presence of PECs. On the contrary, the structure was impacted when increasing r, revealing a heterogeneous aggregate morphology with ladder-like chain interactions.

[Attempt at "conservative medical treatment" in the decompensations of chronic respiratory insufficiencies]. / Essai d'un "traitement médical conservateur" dans les décompensations des insuffisances respiratoires chroniques

Study of 37 acute respiratory decompensations occurring in 28 patients over a 6 years period (1969-1975). They were given a systematic "conservative treatment" associating ventilation with a mask or a mouthpiece, physiotherapy and various drugs, intubation being used only in case of failure of this treatment. On the whole 22 compensations were cured by this treatment alone (59%) and the 15 cases that were not were given classical reanimation. Six deaths were reported (16%). Definitely better than those of DUBOIS and PRIGNOT, these results were perhaps due to differences of recruitment, but also to the systematic use of a mechanical ventilatory assistance instead of a continuous oxygen therapy. With attentive care, this category of patients could be given an assisted external but early ventilation, thus sparing them a tracheal intubation more than once out of twice.