Hyperthermia increases the metastatic potential of murine melanoma

Hyperthemia, either alone or combined with radio-, immuno- or chemotherapy, can control tumor growth, but its effect on metastasis is still controversial. In the present study, we investigated the influence of hyperthermia on the metastatic potential of B16-F10 murine melanoma cells. Incubation of melanoma cells at 43 degrees Celsius for 30 min led to a significant decrease in cell viability. About half of the cells survived the acute exposure to heat. These thermoresistant cells displayed a longer lag phase as compared to control unheated B16-F10 melanoma cells. Other parameters of cell growth such as doubling time and saturation density were equivalent in both control and thermoresistant cells. Both control and treated cells were adherent, but thermoresistant cells failed to spread during the first 48 h after heat exposure. B16-F10 cells colonize the lungs of C57BL/6J mice when injected intravenously; the number of lung colonies is a measure of the metastatic potential of injected cells. Median values of 22, 10.5 and 31 colonies per injected mouse were observed for control cells, cells heated to 43 degrees Celsius for 30 min and thermoresistant cells, respectively, with statistically significant differences between groups (Mann-Whitney test, P<0.02). Thus, despite its cytotoxic action, heat exposure induced the acquisition of a more metastatic phenotype in a subpopulation of B16-F10 cells.

Situação de trabalho de médicos egressos de programas de residência médica no Estado de São Paulo / Work situation of physicians graduating from medical residency programs in the State of São Paulo, Brazil

The authors report on a study conducted to analyze the professional situation of physicians residing in the State of São Paulo, Brazil, five years after completion of a medical residency program. At least 50 of the professionals were interviewed in each specialty. A heavy work load was observed in physicians working both in the metropolitan area of the State capital and in other regions of the State. Male doctors had a higher income than female ones. The latter, however, had a higher proportion working in a single specialty, although 16.8 did not practice in the specialty in which they were trained. The most frequent working environment was a hospital, followed by an ambulatory facility and a private office. The metropolitan area physicians exceeded the remaining in teaching activities and public hospital appointments. They had also a higher tendency to work in a different specialty. This study offers significant information with respect to professional decisions as well as regarding the creation or expansion of residency programs.