Bismuth-Based Quadruple Therapy Using a Single Capsule of Bismuth Biskalcitrate, Metronidazole, and Tetracycline Given With Omeprazole Versus Omeprazole, Amoxicillin, and Clarithromycin for Eradication of Helicobacter pylori in Duodenal Ulcer Patients: a Prospective, Randomized, Multicenter, North American Trial | Synapse