Le peuplement humain du Sahara

Sergent Edmond. Le peuplement humain du Sahara. In: Revue internationale de botanique appliquée et d'agriculture tropicale, 33ᵉ année, bulletin n°369-370, Juillet-août 1953. pp. 285-306

Downregulation of ceramide synthase-6 during epithelial-to-mesenchymal transition reduces plasma membrane fluidity and cancer cell motility

International audienceEpithelial-to-mesenchymal transition (EMT) promotes cell motility, which is important for the metastasis of malignant cells, and blocks CD95-mediated apoptotic signaling triggered by immune cells and chemotherapeutic regimens. CD95L, the cognate ligand of CD95, can be cleaved by metalloproteases and released as a soluble molecule (cl-CD95L). Unlike transmembrane CD95L, cl-CD95L does not induce apoptosis but triggers cell motility. Electron paramagnetic resonance was used to show that EMT and cl-CD95L treatment both led to augmentation of plasma membrane fluidity that was instrumental in inducing cell migration. Compaction of the plasma membrane is modulated, among other factors, by the ratio of certain lipids such as sphingolipids in the membrane. An integrative analysis of gene expression in NCI tumor cell lines revealed that expression of ceramide synthase-6 (CerS6) decreased during EMT. Furthermore, pharmacological and genetic approaches established that modulation of CerS6 expression/activity in cancer cells altered the level of C16-ceramide, which in turn influenced plasma membrane fluidity and cell motility. Therefore, this study identifies CerS6 as a novel EMT-regulated gene that has a pivotal role in the regulation of cell migration.Oncogene advance online publication, 17 March 2014; doi:10.1038/onc.2014.55

Ferrovias, doenças e medicina tropical no Brasil da Primeira República Railroads, disease, and tropical medicine in Brazil under the First Republic

Aborda o impacto da malária no âmbito da modernização republicana, basicamente nas ferrovias, que asssumiram então o papel de integrar o território e operar a expansão simbólica e material da nação brasileira. Os cientistas destacados para debelar os surtos epidêmicos não se limitaram a realizar as campanhas. Fizeram observações sobre aspectos da doença, inclusive suas relações com hospedeiros e ambientes, contribuindo com novos conhecimentos e com a institucionalização, no Brasil, de novo campo que então se estabelecia nas potências coloniais européias: a medicina tropical. O artigo articula essas inovações - especialmente a teoria da infecção domiciliária - com as campanhas em prol de ferrovias e com estágio subseqüente no enfrentamento da malária no Brasil, nos anos 1920.<br>The article explores the impact of malaria on infrastructure works - above all, railroads - under the republican drive towards modernization. Railways helped tie the territory together and foster the symbolic and material expansion of the Brazilian nation. The scientists entrusted with vanquishing such epidemic outbreaks did not just conduct campaigns; they also undertook painstaking observations of aspects of the disease, including its relations to hosts and the environment, thus contributing to the production of new knowledge of malaria and to the institutionalization of a new field in Brazil, then taking root in Europe's colonies: "tropical medicine." The article shows the ties between these innovations (especially the theory of domiciliary infection) and the sanitary campaigns that helped the railways, which in the 1920s were followed by a new phase in Brazil's anti-malaria efforts