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Nous rapportons un cas de dermatite lichénoïde annulaire du sujet jeune (DLAJ). Il s’agit d’une dermatose lichénoïde rare affectant principalement la population pédiatrique et présentant des caractéristiques histocliniques stéréotypées. C’est à notre connaissance le premier cas publié dans la littérature francophone.

In this work, the fragmentation of peptides under atmospheric pressure photoionization conditions is investigated. Intensive fragmentations into b/y‐ and c‐sequence ions are reported. Abundance of these c‐ions appeared to be related to the quantity of dopant infused and to the disappearance of the doubly protonated peptide ion. A careful analysis of the role of the dopant indicates that the fragmentations are not dependent on the nature of the dopant but on their ionization efficiencies. This result shows that the fragmentation arises from the reaction of the protonated peptide with photoelectrons released upon ionization of the dopant in an electron capture dissociation/electron transfer dissociation (ECD/ETD) type mechanism. Experiments with peptides bearing a single proton indicate that additional mechanisms are involved. H‐atom transfer reactions are suggested to be responsible for the fragmentations as well. Those atoms could arise either from the dopant ions or from negatively charged solvent nanodroplets. This is the first report of an ECD/ETD mechanism in a dense medium and at atmospheric pressure. Copyright © 2006 John Wiley & Sons, Ltd.

A comprehensive atmospheric pressure photoionization (APPI) mass spectrometry investigation of hexamethonium bromide is reported. This bisquaternary ammonium salt is a model system for the investigation of multiply charged species and elucidation of ion formation processes. It has been used to elucidate the physico–chemical phenomenon occurring when photoionization is carried out at atmospheric pressure. First, the in-source fragmentations were studied for aqueous solutions of the salt with the photoionization lamp switched off, i.e. under thermospray conditions. It is shown that, in this mode of operation, fragmentations are minor and may be classified into two classes, namely dequaternization and charge separation, arising from the two precursors, M2+and [M + Br]+. Second, the fragmentation patterns have been monitored in dopant-assisted APPI for different dopants (toluene, toluene-d8, anisole and Hexafluorobenzene) at various amounts. At low dopant flow rates, the [M + Br]+and M2+ions are still observed. As the flow rate is increased, these precursor ions lose intensity and are finally suppressed for all three dopants. Comparison of toluene and toluene-d8reveals that H atoms may be transferred from the dopant to the molecular ions, very likely mediated by the solvent. The role of the solvent (water) was also investigated by using heavy water. Apart from the thermospray fragmentations, which are also observed in APPI, several fragmentation pathways appear to be specific to the photoionization process. Photoionization efficiencies are measured by determination of the relative photoionization cross sections with respect to toluene. It is found that, when the ionization efficiencies are taken into account, the depletion of the precursors as a function of the dopant flow rates is the same for all three dopant molecules. This result shows that the precursor ions are depleted by reactions with the photoelectrons released from the dopant. Three additional mechanisms are proposed to account for this effect: electron transfer or H atom transfer from negatively charged water nanodroplets and H atom transfer from the dopant.

Le lévamisole, un antihelminthique aux propriétés immunomodulatrices, peut être responsable de vasculites à ANCA de présentation clinique assez particulière bien que relativement spécifique.