Morphological analysis confirmed the effects of hyperglycemia on SIRT-1 expression in the diabetic retinal microvasculature, as shown by double labeling with isolectin B4, demonstrating a down-regulation of SIRT-1-specific immunoreactivity in retinal blood vessels of diabetic rats (Fig 4E and 4F, white arrows) as compared to control (Fig 4D, white arrows) and aging (Fig 4G and 4H) rat retinas. The gene discussed is SIRT1; the disease is Hyperglycemia.