PB treatment

PB was purchased from MilliporeSigma (Burlington, MA, USA). Mice (n = at least 8/group) were arbitrarily assigned to each group and administered PB dissolved in drinking water for 7 d. The 2 doses of PB (9 and 90 μg/ml) were chosen based on calculated conversions from known human dosing in the GW (1). Conversions from human to mouse dosages based on body weight yielded a mouse dose of 9 μg/ml and conversions based on body surface area yielded a mouse dose of 90 μg/ml. Controls were given water only.

Animals were euthanized at 7 or 30 d. Samples of blood, colon, and brain were collected at the time of euthanization. Macroscopic damage was assessed and scored as the colon was removed using a well-characterized scale to quantify colonic length, fecal blood, and diarrhea (23).