ADO and digestive system infectious disorder: In intestinal infections caused by toxin-producing bacteria, the ADO system [1, 68, 92, 119–124] consisting of various mechanisms of synthesis of ADO, of regulation of its levels, and its four ARs, is profoundly involved with effects ranging from the regulation of the inflammatory response to the opposite exacerbation of that response [68, 92, 119, 187–189].