Chromosome mapping of repetitive sequences in Rachycentron canadum (Perciformes: Rachycentridae): implications for karyotypic evolution and perspectives for biotechnological uses.

The cobia, Rachycentron canadum, a species of marine fish, has been increasingly used in aquaculture worldwide. It is the only member of the family Rachycentridae (Perciformes) showing wide geographic distribution and phylogenetic patterns still not fully understood. In this study, the species was cytogenetically analyzed by different methodologies, including Ag-NOR and chromomycin A(3) (CMA(3))/DAPI staining, C-banding, early replication banding (RGB), and in situ fluorescent hybridization with probes for 18S and 5S ribosomal genes and for telomeric sequences (TTAGGG)(n). The results obtained allow a detailed chromosomal characterization of the Atlantic population. The chromosome diversification found in the karyotype of the cobia is apparently related to pericentric inversions, the main mechanism associated to the karyotypic evolution of Perciformes. The differential heterochromatin replication patterns found were in part associated to functional genes. Despite maintaining conservative chromosomal characteristics in relation to the basal pattern established for Perciformes, some chromosome pairs in the analyzed population exhibit markers that may be important for cytotaxonomic, population, and biodiversity studies as well as for monitoring the species in question.

Doença do refluxo gastroesofágico: estudo caso-controle / Gastroesophageal reflux disease and smoking: a case control study

A DRGE é uma enfermidade muito frequente nos consultórios de gastroenterologia. Sua associaçäo com tabagismo apresenta algumas controvérsias, com alguns pontos obscuros na literatura médica. Este trabalho visou correlacionar tabagismo com DRGE de maneira objetiva através de um estudo caso-cpntrole, utilizando métodos estatísticos criteriosos, e mostrou que o tabagismo favorese o aparecimento de esofagite de refluxo. A pesquisa foi realizada através de endoscopia digestiva alta com diagnóstico de esofagite de refluxo (casos) e entre pacientes com exame endoscópico normal (controle). Os resultados obtidos em 138 pacientes submetidos à endoscopia digestiva mostraram 37 com esofagite e 101 normais. Através da análise do qui-quadrado para tendência linear evidenciou-se que a incidência de esofagite foi maior no grupo de pacientes fumantes com tendência ppositiva entre esta doença e o número de cigarros fumados por dia