Figure 3.

Plasma nuclease activity levels. Nuclease activity in plasma samples obtained from cancer and non-cancer patients was measured with the plasmid incision assay using pBR322 plasmid as the substrate. (A) Two representative reactions from non-cancer and cancer patients stained with ethidium bromide following agarose gel electrophoresis. Nuclease activity is proportional to the conversion rate of the intact supercoiled circular plasmid DNA (lower band), to open circular DNA (upper band) or linear DNA (middle band). The non-cancer samples in (A) show reduced levels of supercoiled DNA indicating that they were cleaved by higher levels of plasma nucleases. The calculated relative nuclease activity (B) demonstrated lower activity in cancer patients compared to the non-cancer group (*, P=0.028).