XDH and heart failure: In a study by Soucy et al., exposure of rat aortas to 1 Gy of 56Fe ions led to a significant increase in aortic stiffness and the development of chronic vascular dysfunction by xanthine oxidase (XO)-dependent ROS production and nitroso-redox imbalance, of which the latter has been linked to the development of heart failure (39, 42).