Effect of pre-treatment with S. boulardii on intestinal permeability. Mice from the Control + Sb and Mucositis + Sb groups were pre-treated with 108 CFU of S. boulardii by gavage for 10 days; other groups received saline by gavage. On the 11th day of the experiment, mice from Mucositis group received an intraperitoneal injection of 300 mg/kg of 5-FU. After 72 h, all received 99mDNTP by gavage, and four hours later, they were given general anesthesia and had their blood collected. % dose = (counts per minute of blood/counts per minute of administered dose). (*) Indicates statistically significant differences (p < 0.05), n = 7; data are representative of three different experiments.