Figure 1.

Detection of the cagA gene by Southern blot hybridization. (A) Hybridization for 50 genomic DNA of the isolates and 4 H. pylori reference strains as positive and negative controls, as well as a control the plasmid with the intra-cagA gene cloned, and distilled water as an internal-reaction negative control. (B) Schematic representation of the result of hybridization: circles continuous and discontinuous for positive and negative hybridization, respectively. Abbreviations: CTLS, controls; NPU, non-peptic ulcers; NBPU, non-bleeding peptic ulcers, and BPU, bleeding peptic ulcers.