Thesis, COLLÉGIALITÉ

Abstract

As the population is becoming older, osteoporosis is more and more important worldwide. It affects 200 million women and costs enormously to society. Also, the treatment is not always effective, and the compliance is low. Adverse effects are really important and the absorption of molecules for bisphosphonates, which is the most common therapy, is less than 2%. A follow-up of the treatment is thus necessary, as it is not correctly taken. This follow-up is based on bone formation and resorption markers. In the present work, the focus will be realised on ß-CTX, a degradation product of type 1 collagen. Immunoassays analysing the concentration of ß-CTX in biological samples gave different concentrations when the analysis was realised on a same sample. The work here was part of a larger one which consisted of creating a commutable standard to harmonize every immunoassay. The project was separated in different parts. The first one was the isolation of ß-CTX by liquid chromatography, followed by a characterization by mass spectrometry. Indeed, the structure was still unknown. Finally, the creation of an internal standard and a commutable product was planned. This work describes the isolation part. The isolation was an important part of the work. Indeed, the more the sample was separated, the more ß CTX was pure and the more the characterization was realised easily. Different parameters were tested, such as the addition of ammonium formate, formic acid and DMSO in phases. These were really efficient for the separation. Also, the gradient was optimized, as it was elongated to allow a better separation of the peaks. Finally, the injection solvent was modified, with the removing of the acetonitrile and the addition of DMSO. All these modifications of parameters on the method are described in detail. They lead to a good separation of the peaks and it was thus possible to pass to the second part of the project which was the characterization.