A novel biocompatible hyaluronic acid-chitosan hybrid hydrogel for osteoarthrosis therapy.

A conventional therapy for the treatment of osteoarthrosis is intra-articular injection of hyaluronic acid, which requires repeated, frequent injections. To extend the viscosupplementation effect of hyaluronic acid, we propose to associate it with another biopolymer in the form of a hybrid hydrogel. Chitosan was chosen because of its structural similarity to synovial glycosaminoglycans, its anti-inflammatory effects and its ability to promote cartilage growth. To avoid polyelectrolyte aggregation and obtain transparent, homogeneous gels, chitosan was reacetylated to a 50% degree, and different salts and formulation buffers were investigated. The biocompatibility of the hybrid gels was tested in vitro on human arthrosic synoviocytes, and in vivo assessments were made 1 week after subcutaneous injection in rats and 1 month after intra-articular injection in rabbits. Hyaluronic acid-chitosan polyelectrolyte complexes were prevented by cationic complexation of the negative charges of hyaluronic acid. The different salts tested were found to alter the viscosity and thermal degradation of the gels. Good biocompatibility was observed in rats, although the calcium-containing formulation induced calcium deposits after 1 week. The sodium chloride formulation was further tested in rabbits and did not show acute clinical signs of pain or inflammation. Hybrid HA-Cs hydrogels may be a valuable alternative viscosupplementation agent.

A novel oxido-viscosifying Hyaluronic Acid-antioxidant conjugate for osteoarthritis therapy: biocompatibility assessments.

To overcome the problem of fast degradation of Hyaluronic Acid (HA) in the treatment of osteoarthritis (OA), HA was protected against the oxidative stress generated by the pathology. Antioxidant conjugated HAs were synthesized and tested in vitro for their resistance in an oxidative environment mimicking OA. HA-4-aminoresorcinol (HA-4AR) displayed the interesting property of increasing in viscosity under oxidative conditions because of crosslinking induced by electron transfer. The novel HA polymer conjugate was shown to be biocompatible in vitro on fibroblast-like synoviocytes extracted from an arthritic patient. This HA conjugate was also assessed in vivo by intra-articular injection in healthy rabbits and was found to be comparable to the native polymer in terms of biocompatibility. This study suggests that HA-4AR is a promising candidate for a next generation viscosupplementation formulation.

Comparison of three diagnostic detection methods for tuberculosis in French cattle.

Three additional techniques (Ziehl-Neelsen, auramine O/rhodamine and immunostaining using polyclonal anti-Mycobacterium bovis) to hematoxylin-eosin histopathology were evaluated for bovine tuberculosis diagnosis on 39 samples from several slaughterhouses. The immunohistochemichal technique was more sensitive and could detect a greater number of positive cattle. It has about the same sensibility as the bacteriology but it was faster.

Chronic eosinophilic dermatitis in the scrotal area associated with stephanofilariasis infestation of charolais bull in France.

A species of stephanofilaria is recorded as the cause of chronic eosinophilic dermatitis in the scrotal area of one charolais bull in France. Macroscopical and histopathological description of the lesion are given with a brief description of the parasite.