Schematic of automated apoptotic response measurement at 1-h intervals over 48 h of drug treatments. The coefficient of variation (CV) of nuclear intensity, reflecting DNA fragmentation, served as an indicator of apoptosis. Representative images of non-apoptotic cells treated with DMSO and apoptotic cells after drug treatment (left). Histograms show the distribution of nuclear intensity CV at each time point in approximately 1,00010,000 cells. A fixed threshold (e.g., 14% in the panels) was used to determine the percentage of DNA fragmentation-positive cells (middle). The threshold remained constant for each cell line. DNA fragmentation plots for NCI-H23 cells are shown as an example (right). Scale bar: 10 m.
