Helicobacter pylori (H pylori) raises serum gastrin but it is unclear whether this stimulates increased acid secretion. Gastrin mediated acid secretion and plasma gastrin after the intravenous infusion of gastrin releasing peptide was studied in nine H pylon negative and nine H pylon positive healthy volunteers, and in 11 duodenal ulcer patients. Nine of the last group were re-examined one month after eradication of H pylon.
In the past five years 12 patients have been identified presenting with chronic duodenal ulcer (DU) disease and with no evidence of current or recent Helicobacter pylori (H pylori) infection. Four of them were taking regular non-steroidal anti inflammatory agents, one was subsequently found to have Crohn's disease of the duodenum, and one to have the Zollinger-Ellison syndrome. The remaining six patients with idiopathic DU disease were remarkable for their absence of the A1 blood antigen gene. Detailed studies of gastric function were performed in these six patients and compared with H pylon positive patients with DU and with healthy volunteers. The median integrated gastrin response in the patients with idiopathic DU (2810 (range 750-8750) ng/l min) was similar to that of the H pylori positive patients with DU (3355 (550-8725)) and higher than that of the H pylon negative healthy volunteers (560 (225-1125)). The median peak acid output in the patients with idiopathic DU (37 mmol/h, range 17-52) was similar to that of the H pylon positive patients with DU (40 (15-57)) and higher than that ofthe non-ulcer controls (22 (16-29)). The median percentage of a liquid meal retained in the stomach at 60 minutes was less in the patients with idiopathic DU (23 (15-33)) than in Hpyloni negative healthy volunteers (34 (30-53) p<0-01). The median percentage of a solid meal retained at 60 minutes was less in the patients with idiopathic DU (54 (9-83)) than in either H pylon negative healthy volunteers (87 (49-95) p<001) or H pylon positive patients with DU (79 (51-100) p<0-01). In conclusion, three abnormalities of gastric function are prevalent in patients with H pylon negative idiopathic DU disease -hypergastrinaemia, increased acid secretion, and the one feature distinguishing them from H pylon positive patients with DU -rapid gastric emptying of both liquids and solids. Each of these abnormalities will increase the exposure of the duodenal mucosa to acid and thus explain its ulceration. The absence of the blood group A1 antigen gene is consistent with a genetic basis for the disturbed gastric function linked to the ABO blood group antigen genes. (Gut 1993; 34: 762-768) More than 95% of patients with chronic duo-
Background: Primary aldosteronism (PA), the most common secondary cause of hypertension, can be screened for using the aldosterone/renin ratio. This ratio is raised in PA and its accuracy depends on the ability to measure plasma renin at extremely low concentrations. Methods: We compared two different procedures for assessing plasma renin. The conventional method, which measures plasma renin activity (PRA), is technically demanding and laborious, and the Diasorin Liaison w method, which measures plasma renin concentration (PRC), is an automated immunoassay. Results from each method were used to calculate the aldosterone/renin ratio (ARR) and the performance of the Diasorin Liaison w method compared with that of the conventional assay using receiver operator characteristic curves. Results: The analytical and functional sensitivity of the PRC method were 2.1 and 5 mIU/mL, respectively. Intra-and interassay precision were ,7.2% and 10.4%, respectively. There was significant (9%) prorenin interference. Samples with PRA . 1.0 ng/mL/h showed significant correlation with PRC (r ¼ 0.93; P , 0.05; n ¼ 146); however, with PRA , 1.0 ng/mL/h, no significant correlation occurred (r ¼ 0.14; P , 0.05; n ¼ 79). An aldosterone ( pmol/L)/PRC(mIU/mL) ratio of .35, in patients with aldosterone .300 pmol/L, resulted in 100% sensitivity and 93% specificity, when compared with the commonly accepted aldosterone ( pmol/L)/PRA (ng/mL/h) ratio of .750, in identifying patients who may suffer from PA. Conclusion: This study indicates the feasibility of using the automated PRC assay as a replacement for the conventional manual PRA assay in calculating the ARR as a first-line screen for PA.
The mechanism of the hypergastrinaemia associated with Helicobacterpylori infection is unknown. It may be an effect of the ammonia produced by the bacterium near the antral epithelial surface. We In an attempt to elucidate the mechanism of the hypergastrinaemia associated with H pylori infection, we have examined the effect of inhibiting the bacterium's urease activity and ammonia production on serum gastrin in duodenal ulcer patients. Patients and methods STUDIES IN PATIENTS WITH H PYLORI INFECTIONSix patients confirmed endoscopically to have duodenal ulceration within the previous year but currently in clinical remission were studied. Their median age was 39 years (range 26-52) and three were women. In each patient, an antral biopsy specimen obtained endoscopically within the preceding three months had shown gastritis associated with H pylori like organisms.The patients reported fasted and a venous blood sample was removed at 8 am for gastrin determination. Immediately after this they drank 50 ml water and further blood samples were taken at 30 minute intervals for two hours. At 10 am they took a standard meal consisting of two beef cubes (OXO Ltd, Croydon, England) dissolved in 200 ml water at 50°C. Further blood samples were taken at 10 minute intervals for 70 minutes and a final one at 90 minutes after the OXO drink. Immediately after this sample a "C urea breath test was performed to measure H pyloni urease activity. For this they drank 250 ml Ensure Plus (Abbott Laboratories, England) to delay gastric emptying, followed by 0 4 MBq 14C urea (Amersham International) in 25 ml water. Breath samples for 14C-Co2 analysis were obtained at 10 minute irtervals for 90 minutes.
Circulating testosterone concentrations in infants measured by a direct chemiluminescent immunoassay (Bayer ADVIA Centaur) were compared with those measured by a traditional radioimmunoassay using solvent extraction. The results confirm that neonatal circulating testosterone concentrations are method dependent, and each laboratory should establish method related reference ranges especially if using a direct commercial immunoassay. The results indicate that the Bayer ADVIA Centaur procedure can be used reliably in neonates. Expected values for male and female infants , 10 days old were 2.5-11.1 (n = 36) and 1.7-5.6 (n = 36) nmol/l respectively. For older neonates (10-50 days) the ranges were 0.2-17.2 (n = 42) and 0.1-1.5 (n = 7) nmol/l respectively. A lthough ''direct'' commercial steroid immunoassays are reliable in many clinical situations, concerns remain about their accuracy for steroid measurements in young infants.1 Determination of the plasma concentration of testosterone is an important part of the evaluation of infants with genital abnormalities.2 In affected infants with impalpable testes, the circulating testosterone concentration may indicate the presence of intra-abdominal testes and may also provide some clues about the underlying causes. The aim of this study was to compare neonatal circulating testosterone concentrations obtained by a recently developed and locally available commercial ''direct'' immunoassay (Bayer ADVIA Centaur) with those obtained with a traditional solvent extraction immunoassay. Despite reliable reference ranges for plasma testosterone assayed by extracted radioimmunoassay being described three decades ago, 3 4 there is, rather surprisingly, a lack of more recent information. In addition to comparing the extracted assay with the more widely available direct assays, we have therefore also determined the reference range for plasma testosterone concentrations in young infants. This information should facilitate the management of the infant with genital anomalies. SUBJECTS AND METHODSBlood samples were obtained from a group of infants less than 6 months old having other investigations. Ethical approval was obtained from Yorkhill NHS Trust. Testosterone was measured directly by chemiluminescent immunoassay on the Bayer ADVIA Centaur analyser (sensitivity 0.35 nmol/ l, coefficient of variation , 7.6%) and an in house radioimmunoassay with a preceding solvent extraction step (sensitivity 0.35 nmol/l, coefficient of variation , 8%).Intergroup comparison was performed by the paired t test using SPSS software. Table 1 shows the median concentration and range of plasma testosterone as assayed by both the Centaur ADVIA direct immunoassay and the extraction radioimmunoassay in boys and girls less than 10 days old (n = 36 and 36 respectively) and between 10 and 50 days old (n = 42 and 7 respectively). The overall correlation between assays was good (r = 0.88: n = 121). In both boys and girls aged less than 10 days, significantly lower results (p , 0.001) were obtained by the extraction radi...
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