RESUMEN
Human embryonal carcinoma (EC) cells typically require high cell densities to maintain their characteristic phenotype; they are generally subject to differentiation when cultured at low cell densities, marked by changes in morphology and expression of the surface antigen, SSEA-1. To test whether cadherin mediated cell-to-cell adhesion may be responsible for maintaining an EC phenotype we ascertained that human EC cells generally express E- and P-cadherins, and are subject to cadherin mediated, Ca2+ dependent aggregation. However, in the NTERA2 human EC cell line, inhibition of cadherin mediated adhesion by culture in low levels of Ca2+ did not result in the changes typically seen under low cell density conditions. Low Ca2+ levels also did not affect the pattern of differentiation in these cells following induction with retinoic acid. Therefore, cadherin-mediated cell adhesion does not appear to play a role in maintaining an EC phenotype. On the other hand, culture at both low cell density and in the absence of Ca2+ did result in changes in the patterns of cadherin expression suggesting a feedback regulatory effect of cell-to-cell adhesion. Further, lithium which inhibits the cytoplasmic kinase GSK3beta and hence influences beta-catenin levels did cause differentiation of NTERA2 cells. However, consideration of the phenotype of the resultant cells suggested that this effect may be because of lithium mimicking activation of a Wnt signalling pathway, rather than an effect on signalling consequent upon cadherin mediated cell to cell adhesion.
Asunto(s)
Cadherinas/metabolismo , Adhesión Celular , Células Madre Neoplásicas/metabolismo , Transactivadores , Cadherinas/fisiología , Calcio/farmacología , Recuento de Células , Proteínas del Citoesqueleto/metabolismo , Desmoplaquinas , Relación Dosis-Respuesta a Droga , Células Madre de Carcinoma Embrionario , Citometría de Flujo , Humanos , Litio/farmacología , Células Madre Neoplásicas/fisiología , Fenotipo , Factores de Tiempo , alfa Catenina , beta CateninaRESUMEN
Over a 15 month period, all the scripts written by doctors in the Episkopi Garrison Medical Centre, Cyprus, were analysed. A formulary was produced by using the most popular items in that 15 month period and tested in a one month trial period. The idea was to find a practical and efficient method of producing a 'basic' formulary to which items could be added or removed after discussion with colleagues.