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Swamp and river buffalo mitochondrial DNA (mtDNA) was sequenced for 303 bp of the cytochrome b gene for 54 animals from 14 populations, and for 158 bp of the D-loop region for 80 animals from 11 populations. Only one cytochrome b haplotype was found in river buffalo. Of the four haplotypes identified in swamp buffalo, one found in all populations is apparently ancestral both to the other swamp haplotypes and to the river haplotype. The phylogenetic relationships among the 33 D-loop haplotypes, with a cluster of 11 found in swamp buffalo only, also support the evolution of domesticated swamp and river buffalo from an ancestral swamp-like animal, most likely represented today by the wild Asian buffalo (Bubalus arnee). The time of divergence of the swamp and river types, estimated from the D-loop data, is 28,000 to 87,000 years ago. We hypothesise that the species originated in mainland south-east Asia, and that it spread north to China and west to the Indian subcontinent, where the rive type evolved and was domesticated. Following domestication in China, the domesticated swamp buffalo spread through two separate routes, through Taiwan and the Philippines to the eastern islands of Borneo and Sulawesi, and south through mainland south-east Asia and then to the western islands of Indonesia.

Reflux oesophagitis is a chronic relapsing disorder. When treatment is stopped after successful short-term healing of oesophagitis, high relapse rates (80% within 6 months) indicate that prolonged treatment is necessary in order to maintain remission. The results of three long-term, multicentre, controlled, double-blind clinical trials comparing different regimens of omeprazole with ranitidine are reviewed. Omeprazole, 20 mg daily, was found to be a highly effective maintenance therapy in patients with ulcerative oesophagitis, keeping 67-89% of patients in remission for 1 year, compared with 10-25% of patients treated with ranitidine, 150 mg twice daily. Weekend omeprazole therapy, 20 mg daily every Friday, Saturday and Sunday, was, as with daily ranitidine, relatively ineffective. All treatment regimens were well tolerated and gastric mucosal biopsies showed no qualitative changes in gastric enterochromaffin-like cells.

To assess the influence of ethnic origin on the incidence of HLA antigens in duodenal ulcer, we typed 160 white Australian patients (including 22 born in Greece or Italy) and 320 blood donor controls for the HLA-A and -B loci. 5 of the 22 (22.7%) southern European patients, but only 19 of the 138 (13.8%) of the remaining duodenal ulcer patients were found to have antigen B5 compared with 27 (8.4%) of the controls. HLA-B12 was found in 55 (34.4%) duodenal ulcer patients (including 6 of the 22 southern European patients) and 117 (36.6%) controls. No significant association of duodenal ulcer with HLA-B5 or HLA-B12 was found when differences in racial origin of patients were taken into account.