| Cancer and birth defects result from DNA damage, which causes somatic or germinal mutations. Radiation therapy and chemotherapy can also produce significant amount of DNA damage. Comet assay is a widely used mechanism for assessing DNA damage because it is a very sensitive technique for detecting damage in individual cells. The technique is a method for visualizing double or single DNA strands, which have been damaged to varying degrees, suspended in a gel and made to migrate under the influence of a weak electric field. The intensity distribution in the tail of the comet reflects the amount of fragmented (damaged) DNA.; There are four kinds of techniques for quantifying this type of damage. We have devised an algorithm for accurately quantifying the amount of damage in comets produced by any type of damaging agents. The data smoothing is carried out over several neighboring pixels in the extracted image file to remove the inherent experimental errors. Circular symmetry and the average of three radii are used to define the comet head. The integrated intensity area under the head is calculated, followed by the total area of the entire comet. A ratio of the head to the total comet area gives the measure of the extent of damage done to the DNA in each examined cell. Our technique is advantageous over the other techniques in terms of speed, automation and the lack of human interaction. The data imply that it could be developed into a diagnostic test for detecting chronic lymphocytic leukemia.; In addition, the ‘spreading’ and the evolving shape of the comet tail in the direction perpendicular to the applied electric field was studied. This was described by a diffusion type of model, which was used as a basis to calculate a ‘spreading coefficient’ for the extent of spreading of the comet tail in directions perpendicular to motion along the field. The calculated ‘spreading coefficient’ was empirically found to be inversely related to DNA lengths over the migrational distance of the comet. |
