Light microscopy

We scored the kidney pathology in periodic acid–Schiff (PAS)–stained paraffin sections, as previously detailed [30]. Briefly, luminal hyaline casts were assessed in 10 fields for each section. The number of casts was counted under 200× magnification, and the mean number per field was calculated. To evaluate the renal tubular injury, 10 fields from each section were evaluated under 400× magnification. The extent of tubular injury was assessed by counting the percentage of areas with tubular dilatation, tubular cast, and tubular epithelial cell necrosis per field. Scores from 0 to 4 were used (0, none; 1, <10%; 2, 10%– 25%; 3, 25%– 50%; 4, >50% of areas injured), and the results were averaged.