A Framework for Automatic Recognition of Cell Damage on Microscopic Images using Artificial Neural Networks.

Despite several technological advances in the past years, the vast majority of microscopy examinations continue to be performed in a very laborious, time-consuming manner, requiring highly experienced personnel to spend several hours to visually examine each microscope slide. Due to recent improvements in modern Digital Image Processing, professionals that work on microscopic exams could benefit from new tools that can apply image processing possibilities to their specific field. We propose a framework consisting of an image segmentation stage, feature extraction, and then a Shallow Neural Network related to human perception. The framework is used to classify among 5 types of animal cell damage analyzed in a case study. The case study used applies the Single Cell Gel Electrophoresis assay (SCGE, also known as comet assay) to the cells of land mollusk Helix aspersa in order to measure the DNA damage caused by mutagenic agents. To train and analyze the performance of our approach, we used a dataset manually segmented by a biologist and comprised of 130 slide samples with labeled cells. Our framework proved to be robust, achieving an average accuracy of 88.3%.

Genotoxic effects of the alkaloids harman and harmine assessed by comet assay and chromosome aberration test in mammalian cells in vitro.

Harman and harmine are beta-carboline alkaloids which are present in plants widely used in medical practice, in beverages used for religious purposes in Brazil, as well as in tobacco smoke and over cooked food. In view of the controversial results observed in the literature about the mutagenic effects of these alkaloids, we studied their cytotoxic and genotoxic effects in V79 Chinese hamster lung fibroblasts in vitro using single-cell gel assay, Comet assay, either in the presence or in absence of an exogenous metabolic activation system (S9-mix), and by the chromosome aberration test without S9-mix. Harmine was more cytotoxic than harman. Both harman and harmine increased aberrant cell frequency and induced DNA damage by the Comet assay. These results suggest that harman and harmine are genotoxic in V79 cells, probably as a consequence of their ability to induce DNA strand breaks.

Heat shock changes the response of the pso3 mutant of Saccharomyces cerevisiae to 8-methoxypsoralen photoaddition.

A putative tolerance, induced by heat shock (HS), to the lethal and mutagenic effects of 8-methoxypsoralen (8-MOP) photoaddition and hyperthermia was analyzed in Saccharomyces cerevisiae using the wild-type strain N123 and the isogenic DNA repair-deficient mutant pso3-1. In wild-type cells, the HS (38 degrees C for 1 h) did not modify either the survival or the mutation frequency observed after 8-MOP photoaddition, even though it conferred protection against the lethal effect of hyperthermia (50 degrees C). In the pso3-1 mutant, HS induced an increase of the survival, and a decrease of the mutation frequency, after 8-MOP photoaddition and it also protected against the lethal effect of hyperthermia. The responses induced by HS were specific for 8-MOP photoaddition, since they were not observed after 254 nm ultraviolet-light damage. These results indicate that the protection conferred by HS depends of the type of lesion, and operates through the induction of different repair processes. In the pso3-1 mutant, HS could channel the repair intermediates to and error-free repair pathway.