Calibration And Standardization

Calibration of the comet assay is based on the fact that ionizing radiation produces strand breaks in DNA with known efficiency.[16] By using the comet assay to measure the breaks introduced into cells irradiated with different doses of X-rays, a standard curve can be obtained (Fig. 2), allowing conversion of the comet assay parameters (percent DNA in tail or tail moment) in break frequency. With this approach, the sensitivity of the method has been evaluated as less than 0.5 breaks/109 Da of DNA,[17] similar to other established methods for DNA damage measurement.1-16-1 However, the comet assay saturates at lower levels of damage. A comparison between different methods for oxidative DNA damage detection was recently conducted by a European group to validate current protocols for the measurement of DNA oxida-tion.[18] This concerted effort showed that the values of

Fig. 2 Example of a calibration curve obtained by X-ray. Lymphocytes were embedded in agarose and irradiated with a range of doses before lysis and electrophoresis. The percent of DNA in the tail (open circles) and the tail moment (solid circles) are plotted. (From Ref. [17].)

X-ray dose, Gy

Fig. 2 Example of a calibration curve obtained by X-ray. Lymphocytes were embedded in agarose and irradiated with a range of doses before lysis and electrophoresis. The percent of DNA in the tail (open circles) and the tail moment (solid circles) are plotted. (From Ref. [17].)

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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