Figure 2.

Summary of segmented px density results. (A) Exemplar image of the upper right quadrant of a U87 control dish after all image processing steps (scale bar = 5 mm). Inset graph shows the calculated px densities from bands 1-22 (see D). Zoomed patches near the center and edge are shown (scale bar = 0.25 mm). (B) Corresponding treated dish. Note the increasing trend in px density with EF amplitude. (C) Image processing steps. To the right, an exemplar raw image for U87 cells (top) is compared to the final, binarized image (bottom). (D) Diagram of the discretization of the dish into 25 equal annular bands. The included area is shaded. (E) Aggregated results. The difference between normalized px densities for different cell lines is plotted as a function of both radial distance (bottom axis) and EF amplitude (top axis) using Eq. (1) for axis conversion. Error bars = 90% confidence intervals from bootstrapped pair-wise differences with 1000 re-samplings. One-sample Wilcoxon signed rank tests were also performed band-wise to find significant changes in the treated vs. control difference (* = P < 0.05). The number of replicates was N = 15, 24, 21, 12, 18 for, in legend order, rat astrocytes (Astro), U118, U87, GSC827, and GSC923, respectively. Note that the smaller bands are expected to have fewer cells and thus higher variability.