Genotoxic effects of rotenone on cultured lymphocytes

Rotenone is a heterocyclic compound widely used as an insecticide, acaricide and piscicide. Its toxicity is mainly caused by the inhibition of mitochondrial respiratory processes and ATP production, resulting in the generation of reactive oxygen species. Reactive oxygen species can interact with DNA, RNA and proteins, leading to cell damage, followed by death. We used the Comet assay, and we analyzed chromosome aberrations, in order to evaluate the genotoxic and clastogenic effects of rotenone on the different phases of the cell cycle. Cultured human lymphocytes were treated with 1.0, 1.5 and 2.0 microg/mL rotenone during the G1, G1/S, S (pulses of 1 and 6 h), and G2 phases of the cell cycle. Rotenone induced DNA damage and was clastogenic, but the clastogenicity was detected only with treatments conducted during the G1/S and S phases of the cell cycle. Rotenone also induced endoreduplication and polyploidy in treatments made during G1, while it significantly reduced the mitotic index in all phases of the cell cycle.

Redução de speckle em imagens médicas por ultra-som utilizando o método de diversidade de fase / Reduction of speckle in medical imaging by ultrasound using the method of phase diversity

Ultrasound B mode image is characterized by a deterministic artifact know as speckle. It comes from destructive coherent interference effects between overlapping echoes...

Histochemical characterization of NADPH-diaphorase activity in area 17 of diurnal and nocturnal primates and rodents

NADPH-diaphorase (NADPH-d) activity was studied comparatively in area 17 of four mammalian species, two primates and two rodents. Three brain hemispheres each from adult capuchin-monkeys, owl-monkeys, agoutis and guinea pigs were fixed with aldehyde fixatives by perfusion and 200 mum sections were submitted to NADPH-d histochemistry, using the indirect malic enzyme method. In all species studied the neuropil pattern of enzyme activity presented a clear layered appearance. In primates, histochemical staining was most intense in layer IVc, while in rodents the highest intensity of the neuropil reaction was in supragranular layers (II and III). Comparison of cell density in grey and white matter showed that the majority of NADPH-d-positive neurones were located in the white matter of primates but not of rodents. Since NADPH-d is a nitric oxide synthase the results are very important for comparative functional studies of neuromediators and their correlations with laminar and modular organization of area 17 of the mammalian brain.

A portable microprocessor-based triggering device for cardiac muscle electrical stimulation

We describe a microprocessor-based programmable triggering instrument designed to control the distribution in time of electrical stimuli delivered to a heart muscle preparation. Sequences of stimuli may be selected among those stored in the non-volatile memory of the instrument and new sequences may be programmed using a repertory of 25 commands. The instrument was used to study the inotropic effects of three irregular sequences of stimuli applied to the isolated rat left atrium. The mean peak tension developed by the tissue was unaltered by stimulus sequences, provided the mean stimulatory frequency (2 or 5 Hz) was maintained. The instrument may be useful to study the effect of different stimulatory patterns on cardiac inotropism, as well as for controlling the electrical simulation of tother biological preparation