A preliminary study of an alternative method for evaluating skin sensitizing potential of chemicals.

BACKGROUND: In order to comply with the European legislation concerning the risk assessment of skin sensitizers, considerable progress has been made in developing alternative methods, such as human cell line activation test (h-CLAT). H-CLAT is based on cytometric measurement of fluorescence emitted by anti-CD54 and anti-CD86 antibodies in THP-1 cells. Following this method, a range of substances have been analyzed; the emitted fluorescence, generally at low intensity, has caused problems concerning the interpretation of results. AIM: Find an alternative parameter to h-CLAT for evaluating the sensitizing potential of chemicals. MATERIALS AND METHODS: Cells have been analyzed with flow cytometry after treatment with sensitizing compounds administered at non-cytotoxic concentrations. RESULTS: Sensitizers were able to inducealterations in cell morphology to a more 'condensed' one allowing the identification of cells under microscope as a 'sensitized' subpopulation. These variations cause similar modifications in 'scattering' parameters, making cells easily monitorable by flow cytometry. No changes have been observed in cells treated with non-sensitizers or in untreated cells. CONCLUSION: This method based on the analysis of forward scatter and side scatter parameters, can be used as an alternative method for identifying sensitization potential of chemical compounds.

CONTEXTE: Pour se conformer à la législation européenne en matière d'évaluation des risques des sensibilisants cutanés, beaucoup des progrès ont été fait dans le développement de méthodes alternatives comme le test d'activation de la lignée cellulaire humaine (H-CLAT). H-CLAT se base sur la mesure cytométrique de la fluorescence émise par les anticorps anti-CD54 et anti-CD86 dans les cellules THP-1. Suivant cette méthode, une gamme de substances a été analysée; la fluorescence émise, généralement de faible intensité, a posé des problèmes d'interprétation des résultats. OBJECTIF: Trouver un paramètre alternatif à h-CLAT pour évaluer le potentiel sensibilisant des produits chimiques. MATÉRIAUX ET MÉTHODES: Les cellules ont été analysées par cytométrie en flux après le traitement avec des composés sensibilisants administrés à des concentrations non cytotoxiques. RÉSULTATS: Les sensibilisateurs ont pu induire des altérations de la morphologie cellulaire en une morphologie plus condensée, permettant l'identification des cellules au microscope comme sous-population sensibilisée. Ces variations entraînent des modifications similaires des paramètres de "scattering", rendant les cellules facilement contrôlables par cytométrie en flux. Aucun changement a été observé dans les cellules traitées avec des agents non sensibilisants ni dans les cellules non traitées. CONCLUSION: Cette méthode basée sur l'analyse des paramètres de "forward" et "side scatter" peut être utilisée comme méthode alternative pour identifier le potentiel de sensibilisation des composés chimiques.

Analysis of gene expression in two large schizophrenia cohorts identifies multiple changes associated with nerve terminal function.

Schizophrenia is a severe psychiatric disorder with a world-wide prevalence of 1%. The pathophysiology of the illness is not understood, but is thought to have a strong genetic component with some environmental influences on aetiology. To gain further insight into disease mechanism, we used microarray technology to determine the expression of over 30 000 mRNA transcripts in post-mortem tissue from a brain region associated with the pathophysiology of the disease (Brodmann area 10: anterior prefrontal cortex) in 28 schizophrenic and 23 control patients. We then compared our study (Charing Cross Hospital prospective collection) with that of an independent prefrontal cortex dataset from the Harvard Brain Bank. We report the first direct comparison between two independent studies. A total of 51 gene expression changes have been identified that are common between the schizophrenia cohorts, and 49 show the same direction of disease-associated regulation. In particular, changes were observed in gene sets associated with synaptic vesicle recycling, transmitter release and cytoskeletal dynamics. This strongly suggests multiple, small but synergistic changes in gene expression that affect nerve terminal function.