Recommendations for investigation of hyperandrogenism.

1. Total testosterone assay is recommended as the first-line approach. 2. Radioimmunological assay following prior treatment of the sample (extraction or extraction + chromatography) is the recommended method pending wider experience with mass spectrometry. 3. Where testosterone is twice the upper limit of normal, it is recommended that DHEAS assay be performed. DHEAS is primarily of cortico-adrenal origin in women. Thus, a DHEAS level over 600 mg/dl indicates a diagnosis of androgen-secreting adrenal cortical adenoma.. If DHEAS is normal, the diagnosis could be either ovarian hyperthecosis, normally associated with insulin resistance, or androgen-secreting ovarian tumour. 4. More rarely, elevated testosterone is associated with a marked elevation of SHBG possibly as the result of use of medication having an estrogenic effect (tamoxifen, raloxifene, Op'DDD), or of hyperthyroidism or liver disease. 5. Normal testosterone levels in patients with clear clinical symptoms of hyperandrogenism (hirsutism, seborrhoeic acne) must be interpreted with care. SHBG is normally reduced in the event of overweight, metabolic syndrome or familial history of diabetes.

Relation between the degree of acetylation and the electrostatic properties of chitin and chitosan.

A series of chitosan/chitin samples with DA's varying between 5.2 and 89% was prepared from the reacetylation under soft conditions of a unique chitosan sample allowing the preservation of the chain distribution. The study of the variation of pH for the same concentration of amine groups, at different ionic strengths, on the scale of DA's allows us to extrapolate the variation of pKa at dissociation degrees (alpha) 0 and 1. A modeling of all the curves was obtained by means of only one equation. Then, for given concentration of chitosan and ionic strength, it is possible to predict the pH of the solution whatever the DA and alpha. The role of DA through the participation of hydrophobic interactions and hydrogen bondings on the electrostatic parameters is discussed. The results allow a better understanding of some physicochemical and biological properties of chitosan and chitin.

Interactions between chitosan and glycosaminoglycans (chondroitin sulfate and hyaluronic acid): physicochemical and biological studies.

Chitosan is a polysaccharide well known for its numerous and interesting biological properties, indeed, it is a biocompatible, bioresorbable and bioactive biopolymer. It is therefore often introduced in the human body, where it happens to be in contact with glycosaminoglycans (GAG's), especially chondroitin sulfates and hyaluronic acid which play important part in living media. Thus it seems interesting to consider systems associating chitosan and GAG's. The aim of our work is to study the mechanism of formation of biomaterials constituted of chitosan and GAG's which could have interesting biological properties such as improving the wound-healing acceleration and the cellular assistance for skin and cartilage recovery. In the same time, it was interesting to try to understand what can happen when chitosan is introduced in a natural surrounding containing GAG's. In a first part, the complexes between chitosan and GAG's were characterised by various physicochemical techniques: pH-metry, conductometry and Infra-red spectrometry. They appeared to be polyelectrolyte complexes obtained by the formation of polyanion-polycation interactions held between ammonium functions of chitosan and carboxylate and/or sulfate groups of GAG's. The complexes formed are very strong and can, in some cases, even conduct to the deprotonation of carboxylic functions. In a second part we considered the biological properties of the complexes previously obtained. The hydrolysis activity in presence of specific enzymes was investigated. We also studied the cytocompatibility of chitosan alone and its complexes with the two considered GAG's toward two kinds of cells (chondrocytes and keratinocytes). At the end of the work, a short animal experimentation on rats was performed allowing the comparison between in vitro and in vivo results.

Chitosan-chondroitin sulfate and chitosan-hyaluronate polyelectrolyte complexes: biological properties.

In this work, we compare some biological properties of a highly deacetylated chitosan to those obtained with the materials made from its polyelectrolyte complexes with various GAG's such as chondroitin-sulfates and hyaluronic acid. The hydrolysis of the complexes by means of the specific hydrolytic enzymes is studied. Cell-adhesion and cell-proliferation on these materials is compared to that obtained with a pure chitosan material. Finally, a series of in vivo experiments is performed to test the wound-healing properties of this kind of complexes. All the results agree to show that chitosan has a protective effect against GAG's hydrolysis by their specific enzymes but only at pH's different from the optimal pH of the enzyme considered. In addition, they also agree to confirm that a pure chitosan material gives the best results in connection with cell-attachment and cell-proliferation or wound healing. Nevertheless, whatever the case, no adverse effect was observed with the polyelectrolyte complexes GAG's-chitosan.

Capillary electrophoresis of glycosaminoglycan-derived disaccharides: application to stability studies of glycosaminoglycan chitosan complexes.

Capillary zone electrophoresis (CZE) was used to separate the disaccharides produced by chondroitinase digestion of chondroitin sulfates. The main disaccharides formed upon depolymerization have identical charge and mass. Baseline resolution of these two compounds was achieved by selecting appropriate concentration and pH of a borate buffer. Validation of the method showed a good linearity of the response and a very satisfactory reproducibility of migration times with a relative standard deviation (RSD) of less than 0.4%. The reproducibility of peak areas was improved by using an internal standardization. The addition of cinnamic acid (internal standard) to the incubation medium allowed us to perform kinetic measurements of the depolymerization while keeping a baseline resolution of the two main disaccharides analyzed during the complete digestion course even when their concentration in the incubation medium increased. Application of this method to the comparison of the rate of hydrolysis of chondroitin sulfate and of a complex associating chondroitin sulfate with chitosan showed clearly that, at the physiological pH, chitosan protected the chondroitin sulfate from depolymerization. This phenomenon was more pronounced as the pH of the incubation medium was far from the optimum pH activity of the chondroitinase.

[Characterization and simultaneous assay of polymers and additives composing multilayer plastic material for pharmaceutical use by FTIR]. / Caractérisation et dosage simultanés des polymères et des additifs constitutifs d'un matériau plastique multicouches à usage pharmaceutique, par IRFT.

Multilayer plastic materials provide useful solutions for primary pharmaceutical formulae (maintaining physical properties, compatibility with contents, protection against exterior agents). Fourier transform infrared spectometry is an ideal method to identify and quantify the different polymers and additives. Each functional group has a characteristic band which can be selected and rapidly identified for routine quality control. The proportional quantities of each polymers in the multilayer system can be determined directly using the characteristic bands for each functional group. The technique was applied to the analysis of heat-formed platelets made of polyvinyl chloride and polyvinylidene chloride.