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Helicobacter pylori (H. pylori) infection leads to profound changes in gastric physiology. Several clinical and animal studies have been performed to clarify the influence of H. pylori on gastric acid secretion. Published data, however, are not consistent throughout. Infection of the gastric antrum, which can be observed mainly in duodenal ulcer patients, increases gastrin release and consecutively acid output. The net effect of corpus and antrum gastritis, such as in patients with gastric cancer, is to decrease acid secretion. Chronic H. pylori infection may finally promote gastric atrophy with irreversibly diminished acid secretion but in earlier stages of this infection eradication of H. pylori normalizes gastric secretory activity.

Basic Problem and Objective of Study: The power of resolution of conventional imaging methods is too low for the diagnosis of very small pancreaticobiliary tumours. High-frequency ultrasound transducers (20 MHz), adapted to the dimensions of the pancreaticobiliary systems (2 mm diameter), make intraductal ultrasound examination possible during endoscopic retrograde cholangiopancreatography (ERCP). In a prospective study the invasiveness and diagnostic value of intraductal ultrasound (IDUS) was compared with ERCP, endosonography (ES) and computed tomography (CT)., Patients and Methods: During ERCP in 51 consecutive patients an intraductal ultrasound transducer was introduced into the pancreaticobiliary duct system, the results being compared with those obtained with the other imaging modalities and histopathological findings, if available., Results: IDUS of the pancreatic and bile duct systems is a rapid, simple and reliable method during ERCP and provides valuable additional information on periductal tissues. In the diagnosis of carcinoma of the pancreas its sensitivity was 75% (six of eight cases), that of ERCP 37% (3/8), ES 50% (4/8) and CT 37% (3/8). In the diagnosis of biliary tract tumour the sensitivity of the different modalities (in the above order) was 89% (8/9), 78% (7/9), 33% (3/9) and 33% (1/3). Specificity was 67% (2/3), 67% (2/3), 67% (2/3) and 33% (3/9); predictability 89%, 88%, 75% and 60%., Conclusions: The use of small ultrasound catheter transistor system in the biliary and pancreatic ducts, introduced during ERCP, is technically simple and has few complications. It is a valuable addition to ERCP in the precise diagnosis of small pancreaticobiliary lesions.

Unlike the stimulation of gastric acid secretion, which clearly involves the release of gastrin, the mechanisms of inhibition of this secretory process are poorly defined although recent studies in animals with the use of highly selective cholecystokinin (CCK) antagonists indicate that CCK may play a crucial role in this inhibition. Duodenal ulcer patients (DU) differ from healthy controls by higher total acid secretory rates and diminished inhibition of acid secretion. Several possible pathomechanisms of the abnormal gastric secretory function in DU patients were previously proposed. The deficiency of CCK-induced gastric inhibition in DU patients together with the somatostatin hypothesis appear to be attractive, particularly so the suggestion that a deficiency of somatostatin activity exists in DU patients.

In 1987 it was demonstrated that the vascular endothelium produces nitric oxide, a gas that acts as highly labile but very potent relaxing factor for the vascular smooth muscle. During the last 5-6 years, a series of discoveries from many different avenues of research came together revealing the major biological role of NO as neurotransmitter in the nervous system and other parts of the body, as a potent vasodilating and cytoprotective substance, as mediator of endotoxin-induced cytotoxicity and as a substance involved in various disorders such as liver cirrhosis and reactions of the immune system. Recent studies suggest that in addition to VIP and ATP, NO may mediate non-adrenergic, non-cholinergic (NANC) inhibition of gastrointestinal smooth muscle and related inhibitory junction potentials. The identity of action of NO and NANC nerve stimulation has been supported by numerous in vitro and in vivo studies on esophagus, stomach, small intestine and colon of various species including humans.