The Argentina offices of the Canadian Trade Commissioner Service, responsible for Argentina and Paraguay and based out of Buenos Aires, includes eight trade commissioners. Export Development Canada serves Argentina from its So Paulo, Brazil, offices and travels to the market on a regular basis. The Canadian Commercial Corporation serves Argentina through its office in Lima, Peru. The Argentine-Canadian Chamber of Commerce has been in operation since 1977, when it was set up to help grow and strengthen ties between its members, providing support to both Canadian and Argentine business communities. Today, the chamber is particularly active, with its membership representing significant twoway trade and investment interests, supporting jobs, commercial and technology development and economic growth in both countries. 27 What is the difference between the management of a gastric and of a duodenal ulcer? 28 How does omeprazole suppress Helicobacter pylori? 29 Does omeprazole cause rebound hyperacidity? Does this also apply to H2-blockers? 30 On (K&C 7e, p. 249), you state that the postsynaptic neurotransmitter that inhibits the relaxation of lower oesophageal sphincter (LOS) is nitric oxide (NO). I have understood NO to promote relaxation of LOS by acting on the non-adrenergic, non-cholinergic (NANC) inhibitory neurones, which inhibits the action of cholinergic excitatory neurones. Could you please explain this paradox? 31 It is stated that nitric oxide (NO) inhibits the relaxation of the lower oesophageal sphincter (LOS) and that sildenafil is given for treating achalasia. As far as I know, sildenafil acts to increase the guanine monophosphate (GMP), just as NO uses the same mechanism to relax the LOS. Could you explain this paradox? 32 In Kumar and Clark Clinical Medicine you mention that auscultation is not important in cases of gastrointestinal disorders, but Harrison's Principles of Internal Medicine gives this as being of equal importance because succussion splash and bowel sounds can help in presumptive diagnosis. Succussion splash indicates gastric obstruction (e.g. gastroparesis) and likewise bowel sounds can help determine the status of developing ileus. Would you agree that this is therefore a diagnostic tool? 33 Is it hazardous to give aspirin in the antiplatelet doses (75-325 mg/day) to a patient with a past history of haematemesis proved to be from a peptic ulcer? 34 How can upper gastrointestinal (GI) bleeding be distinguished from lower GI bleeding by using faecal analysis?