Hepatocytes, rather than leukocytes reverse DNA damage in vivo induced by whole body y-irradiation of mice, as shown by the alkaline comet assay

DNA damage repair was assessed in quiescent (G0) leukocytes and in hepatocytes of mice, after 1 and 2 hours recovery from a single whole body y-irradiation with 0.5, 1 or 2 Gy. Evaluation of single-strand breaks (SSB) and alkali-labile sites together were carried out by a single-cell electrophoresis at pH>13.0 (alkaline comet assay). In non-irradiated (control) mice, the constitutive, endogenous DNA damage (basal) was around 1.5 times higher in leukocytes than in hepatocytes. Irradiation immediately increased SSB frequency in both cell types, in a dose-dependent manner. Two sequential phases took place during the in vivo repair of the radio-induced DNA lesions. The earliest one, present in both hepatocytes and leukocytes, further increased the SSB frequency, making evident the processing of some primary lesions in DNA bases into the SSB repair intermediates. In a second phase, SSB frequency decreased because of their removal. In hepatocytes, such a frequency regressed to the constitutive basal level after 2 hours recovery from either 0.5 orí Gy. On the other hand, the SSB repair phase was specifically abrogated in leukocytes, at the doses and recovery times analyzed. Thus, the efficiency of in vivo repair of radio-induced DNA damage in dormant cells (lymphocytes) is quite different from that in hepatocytes whose low proliferation activity accounts only for cell renewal.

Emociones mixtas y conducta de riesgo / Mixed emotions and risk behavior

En este trabajo se explora el papel que la experiencia emocional mixta juega en la predicción de una conducta de riesgo (viajar en un vehículo sabiendo que el conductor ha bebido). Estas emociones se pueden diferenciar del componente evaluativo de las actitudes. En una muestra de jóvenes con experiencia en la práctica de esta conducta de riesgo, observamos que recordaban haber sentido emociones de valencia opuesta (alegría y miedo) antes, durante y después de realizarla. Esta experiencia emocional mixta, junto con la medida de actitud, son los indicadores que mejor predicen la intención de repetir la conducta en el futuro. Los resultados señalan que la experiencia emocional podría estar actuando como variable moderadora de la influencia de las actitudes sobre la intención conductual