SUMMARY Simultaneous ambulatory records of gastric antral and body pH were made over 24 hours in nine healthy volunteers by means of endoscopically positioned and anchored glass electrodes. Intragastric pH was temporarily raised after the endoscopy with the median pH value 30 minutes after the procedure being 3.9 (range 1 5-70) for the antrum and 4.1 (range 1 5-70) for the body. Daytime pH (median pH value between 1200 h and 2300 h) was lower in the antrum (median=1.9, range 16-2.6) than in the body (median=2.7, range 1.8-45) (p<0O05) and this was because of the rise in pH on eating being less marked in the antrum than in the body. The median peak pH recorded during the evening meal was only 4.1 (range 24-642) in the antrum compared with 6.3 (range 4.4-6.7) in the body (p<001). Preprandial pH (median value over the hour prior to the evening meal) was similar in the antrum (median= 1 9, range 1 2-25) and body (median= 1 9, range 1.3-28). Night-time pH (median pH value between 2300 h and 0500 h) in six subjects remained low and was similar in the antrum (median= 14, range 12-1.7) and body (median=13, range 11-1-7). In two subjects, however, there were episodes of raised night-time pH which were more marked in the antrum than in the body. Antral biopsies showed gastritis in four of the nine normal volunteers, which in three was associated with the presence of campylobacter-like organisms. This study shows the significant regional variations in day and night-time intragastric pH.Over the past decade there has been a dramatic increase in the use of ambulatory pH monitoring of the upper gastrointestinal tract (GIT) for research purposes and as an aid to diagnosis. Previously, most studies of intragastric pH depended on the analysis of aspirated gastric juice and had several shortcomings. Gastric aspiration may invoke duodenogastric reflux or stimulate acid secretion' and may be difficult after a solid meal or during the night when little juice is present in the stomach.3 The use of in situ pH electrodes overcomes these problems and also allows the monitoring of pH in specific regions of the stomach rather than just giving a mean intragastric value. Because of the problems of maintaining the position of electrodes within the stomach, little is

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A prospective study of dyspepsia was carried out in a primary referral hospital between 1974-1987 including 1540 patients of whom 1433 were seen as outpatients. The study protocol was agreed in advance and a structured questionary was used to elicit relevant clinical information: up to three diagnoses were permitted for each patient. The commonest principal diagnoses were duodenal ulcer (26%), functional dyspepsia (22%), and irritable bowel sydrome (IBS) (15%); alcohol related dyspepsia (4%) was as common as gastric carcinoma or symptomatic gail stones. Multiple diagnoses were common (31% given two diagnoses, and 6% given three) so that in ali 2111 diagnoses were given to 1540 patients; the functional disorders (IBS and functional dyspepsia) considered together accounted for 39% of ali diagnoses made. Whereas organic conditions were diagnosed by clinicians with confidence (63-98% considered 'certain'), even when given as the principal or first diagnosis IBS was considered 'certain' in only 61% and functional dyspepsia 48%. The demographic symptom data, together with information on tobacco and alcohol use, and work lost are described in detail.

SUMMARY Daytime intragastric pH, fasting and meal stimulated serum gastrin and nocturnal acid output were studied in eight male duodenal ulcer patients before, during and two days after completing nizatidine 300 mg nocte (20 00 h) for four weeks. Median nocturnal acid output (mmoV 10 h) decreased during treatment to 11.6 (range 0.4-26.7) compared with pretreatment value of 39.4 (9-8-91-2); median acid inhibition 770/0 (p<0-01) which was strongest between 2400 and 0400 h. Two days after discontinuing treatment, nocturnal acid output increased to 74.1 (11-181). Compared with the pretreatment value this represents median rebound hypersecretion of 77% (p<0 05), caused by increased H+ concentration and volume of secretion. Overall median daytime intragastric pH (0900-2100 h) was unchanged on the final day of treatment and two days after completing therapy, compared with the pretreatment values. Fasting serum gastrin measured between 09 30 and 10 00 h and the integrated gastrin response to an OXO breakfast taken at 10 00 h were also similar during and after treatment, compared with pretreatment values. The rebound nocturnal hypersecretion may be relevant to the high ulcer relapse rates after stopping H2 receptor antagonists.Nizatidine is a new H2 receptor antagonist which is four times more active on a molar basis than cimetidine and of similar potency to ranitidine.' 2 In addition, nizatidine has a shorter duration of action (plasma half life 1.5 h)3 than either cimetidine (1.9 h) or ranitidine (2.5 h).4 Although the effects of single doses of nizatidine on basal and stimulated acid secretion are known356 the effect of longer term therapy has not been studied. In the assessment of a new H2 receptor antagonist it is important to show adequate suppression of nocturnal acid secretion as this has established benefit in ulcer healing.7 This study was designed to determine the effect of four weeks nizatidine treatment on nocturnal gastric acid output, daytime intragastric pH and serum gastrin. 79) with a past history of endoscopically confirmed duodenal ulcers were studied while in clinical remission. None of the patients had received H2 receptor antagonist therapy within two weeks of starting the study. Their mean weight was 76 kg (range 52-89), and seven were cigarette smokers. Six patients had previously undergone multiple gastric secretion tests as part of a previous study. STUDY DESIGNEach patient was studied before starting nizatidine therapy, on the final day of a 28 day course of nizatidine 300 mg taken at 20 00 h, and again two days after completion of therapy. On each occasion daytime intragastric pH, fasting serum gastrin, integrated gastrin response to a standard OXO breakfast and nocturnal acid output were studied. To ensure study compliance each patient was contacted on their penultimate day of treatment and regular capsule counts were carried out.