SAN FRANCISCOPublic-bus passenger Kyle Renner is seriously getting into a nearby stranger's nursing textbook, downtown-bound sources reported Monday. 'An Unna's boot can be used to treat uninfected, non-necrotic leg and foot ulcers,' read page 182 of the textbook propped up on the lap of the woman seated to Renner's right. 'Alternatively, a preparation known as Unna's paste (zinc oxide, calamine lotion, and glycerin) may be applied to the ulcer and covered with lightweight gauze.' According to Renner, page 182 features a photo of a hand placing a small boot on a smiling elderly woman that was 'pretty funny.' 