[The demonstration of a methodology for identifying and analysing oxygenated sterols present in radicular cysts]. / Mise en place d'une méthodologie d'identification et d'analyse des stérols oxygénés présents dans les kystes radiculo-dentaires.

Our work has two main aims: to identify oxygenated sterols that accompany cholesterol in dental cyst and to develop effective methods for "profile" analyses of these sterols. Attention as focused on a family of products derived from cholesterol, characterized by the presence of one or more oxygenated functions. More than fifty of these oxysterols are known and find most of time in different parts of the body. In the procedure, lipids are isolated from dental cyst, the fraction is trimethylsilylated and analysed by capillary gas chromatography. Sterols are identified by comparison with reference compounds. However, two sterols of particular interest, viz cholesterol alpha and beta epoxides, are so easily produced from cholesterol (even when rigorous precautions are taken) that indirect methods of analysis are strongly advisable. An adequate degree of quantification is possible for sterols such as 26-hydroxycholesterol (26OHCL), which do not arise significantly as artefacts. Even to verify the fraction which seems to be 26OHCL we used thin layer chromatography coupled with mass spectrometer.