D

Fig. 1 Examples of comets in different classes of damage. Images of ethidium bromide-stained nuclei, showing increasing degrees of DNA damage (from image a to e) after electropho-retic migration.

all DNA in the tail. Examples of comets in different classes of damage are given in Fig. 1. Fifty to 100 comets are selected randomly from each slide, and each comet is given a value according to the class it is assigned to, so that an overall score can be derived for each gel from the sum of all the comets' values. The advantage of visual scoring is that it is very quick.

Several software programs are also commercially available that automatically analyze individual comet images acquired in digital form with a CCD camera mounted on a microscope. These programs are designed to provide fluorescence profiles of comet head and tail and to measure various parameters such as percentage of total fluorescence in head and tail, tail length, and ''tail moment'' (conceptually the product of tail length and DNA fluorescence in tail).[6] The percent of DNA in the tail is a widely used parameter and is linearly related to DNA break frequency, up to about 80% in the tail.

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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