Targeted studies as a learning tool in outcomes assessment

BACKGROUND: Gastric lipase secretion is stimulated by gastrin in plasma, but its regulation by secretin is unknown. METHODS: In 7 normal persons we investigated the effect of exogenous secretin on the output of gastric lipase stimulated by intravenous gastrin-17. The gastric content was measured using a nasogastric tube for aspiration. The quantitative lipase secretion was measured by an enzyme-linked immunosorbant assay (ELISA) and the lipolytic activity by a kinetic assay. Plasma concentrations of secretin and gastrin were measured by radioimmunoassay. RESULTS: Gastric lipase secretion (the quantity as well as the lipolytic activity) was significantly stimulated by gastrin. In response to secretin infusion, the lipolytic activity increased as acid secretion decreased. CONCLUSION: Secretin in postprandial concentrations does not influence the quantitative gastric lipase secretion stimulated by gastrin, but it increases lipolytic activity due to inhibition of acid secretion.     

Platelet-derived growth factor BB mediated regulation of 12-lipoxygenase in porcine aortic smooth muscle cells

BACKGROUND & AIMS: Recently, we postulated a new concept of duodenal ulcer pathogenesis suggesting that antral Helicobacter pylori infection blocks inhibitory pathways to the gastrin and parietal cells, resulting in an increased and prolonged postprandial acid secretion. the aim of this study was to examine duodenal acid load and duodenal bulb pH after a meal before and after eradication of H. pylori. METHODS: Using a marker-dilution method and a pH electrode in the duodenal bulb, gastric emptying, acid secretion, gastrin release, duodenal acid load, and duodenal bulb pH were studied during 2 hours after peptone meals of pH 7.0 and 2.0 in 8 H. pylori-negative controls and 8 H. pylori-infected subjects before and 6 months after eradication. RESULTS: The H. pylori-infected subjects had an increased gastric emptying, gastrin release, and acid secretion, higher duodenal acid load, and lower duodenal bulb pH after the meals. These responses were normalized after eradication. CONCLUSIONS: H. pylori-infected subjects have an increased and prolonged postprandial acid secretion, partly caused by an impaired low pH inhibition of acid secretion, gastrin release, and gastric emptying, resulting in an increased duodenal acid load and a prolongation of low pH in the duodenal bulb, as a general prerequisite for the development of duodenal ulcer disease.     

Vagal and hormonal influences on gastric secretion in duodenal ulcer disease

Current concepts on the pathophysiology of gastric hypersecretion in duodenal ulcer disease have been presented and the role of vagal nerves and gastrointestinal hormones particularly gastrin has been discussed. Duodenal ulcer patients form a heterogenous group with regard to the gastric acid and pepsin secretion and gastrin release. They may differ from healthy subjects by several wall defined defects including an increased mass of parietal and peptic cells, increased capacity to secrete acid and pepsin, increased vagal drive to the parietal cells, hyperreactivity of antrum, decreased effectiveness of antral and duodenal autoregulatory mechanisms, defective release of secretin, increased gastric emptying and defective removal of gastric acid load from the duodenum. Very little is known what proportion of duodenal ulcer patients suffer from various pathologic disturbences and what are the mechanisms underlying these changes.     

Influence of bacterial CagA status on gastritis, gastric function indices, and pattern of symptoms in H. pylori-positive dyspeptic patients

OBJECTIVE: To date, little is known about a possible relationship between H. pylori-related disturbances of gastric function and the bacterial virulence. The aim of this study was to assess whether certain gastric function indices as well as the pattern of symptoms in nonulcer dyspepsia (NUD) are related to CagA status. METHODS: A total of 56 consecutive patients with NUD (38 H. pylori-positive and 18 H. pylori-negative) were studied. Dyspeptic symptoms were categorized according to the predominant complaints and scored for severity and frequency. In all subjects, basal and pentagastrin-stimulated acid secretion, fasting and meal-induced gastrin release, fasting serum pepsinogen I (PG I) levels, and gastric emptying of solids were determined. CagA status was determined by assaying serum CagA IgG antibodies by western blotting. RESULTS: Eighteen of 38 (47%) H. pylori-positive dyspeptics were CagA seropositive. Type and severity of dyspeptic symptoms did not significantly differ between CagA-positive and CagA-negative dyspeptics nor between H. pylori-positive and negative patients. Among the gastric function indices studied, only meal-stimulated gastrin was significantly influenced by CagA status (peak gastrin 129.9 [44.1] vs 99.1 [48.6] pg/ml in CagA-positive and negative NUD, respectively), but this was not accompanied by any significant modification of basal or stimulated acid secretion or gastric emptying of solids. The activities of both antral and corpus gastritis in NUD harboring CagA-positive strains were significantly higher than those of CagA-negative NUD. Accordingly, serum PG I levels were significantly higher in CagA-positive than CagA-negative or H. pylori-negative dyspeptics. CONCLUSIONS: These findings support a role for CagA status in influencing the activity and perhaps the distribution of gastritis in NUD, as well as the degree of gastrin response to a meal; however, this is not accompanied by disturbances of acid secretion or gastric emptying or by differences in the type and severity of symptoms.     

Diagnosis of gastrinoma by the secretin suppression test

In contrast to normal physiologic feedback suppression of serum gastrin by secretin, a paradoxic rise in the serum gastrin level has been observed in patients with gastrinoma after the administration of exogenous secretin. Exploitation of this phenomenon in the differential diagnosis of gastrinoma has been restricted by limited individual experience. Serial serum specimens for gastrin radioimmunoassay were collected from 13 patients with histologically proved gastrinoma both before and after the administration of Boot's secretin, 3 units per kilogram. Thirty-nine others with histologically proved gastrinoma who had been studied with exogenous secretin were identified in the literature. Both the peak gastrin and the integrated gastrin responses were increased after secretin administration in each of the patients in this combined series, although the magnitude of the increase was small in four patients. The absence of physiologic suppression by secretin implies neoplastic autonomy of gastrin releasing sites. While an augmented gastrin response to secretin is commonly seen in patients with gastrinoma, from a physiologic standpoint, a lack of suppression constitutes a positive secretin suppression test. Accumulated experience is consistent and suggests that this test is an important adjunt in the differential diagnosis of hypergastrinemia.     

Gastric secretion and motility in duodenal ulcer: effect of current vagotomies

Proximal gastric vagotomy, total gastric vagotomy, and truncal vagotomy all decrease gastric secretion of acid and pepsinogen, increase the concentration of gastrin in the serum, impair gastric receptive relaxation and accommodation, and speed gastric emptying of liquids. Only proximal gastric vagotomy preserves antral motility, gastric emptying of solids, and the pyloric barrier to duodenal-gastric reflux.     

Differential effects of prenatal stress in two inbred strains of rats

Glucagon-like peptide-1 (GLP-1) may be one of the enterogastrone hormones of the ileal brake mechanism. We therefore studied its effects on gastric lipase secretion in healthy volunteers and vagotomized patients during infusion of pentagastrin. The intestinal incretin hormone GLP-1 (glucagon-like peptide-1, 7-36 amide) was investigated because of its inhibitory effects on gastric acid secretion and motility. GLP-1 infused intravenously in amounts corresponding to the postprandial release significantly inhibited pentagastrin-stimulated gastric lipase secretion and lipolytic activity. The inhibitory effect of GLP-1 persisted in vagotomized patients, suggesting that fundic chief cells, from which gastric lipase is released, or neighboring inhibitory cells could be equipped with GLP-1 receptors. Vagotomized patients had significantly higher plasma concentrations of gastrin and secretin. No significant changes of gastrin, secretin, and CCK secretion were seen during GLP-1 infusion in the vagotomized patients, whereas secretin decreased significantly in the healthy volunteers. GLP-1 seems to be a naturally occurring inhibitor of gastric lipase secretion acting via a nonvagal mechanism. Our results indicate that gastric lipase secretion is subject to hormonal stimulatory as well as inhibitory mechanisms.     

Gut regulatory peptide levels in bovine fetuses and their dams between the 3rd and 9th months of gestation

Several gut regulatory peptides were measured by radioimmunoassay between 3 and 9 months of gestation in the plasma of 91 bovine fetuses and their dams, in fetal gastric content and in amniotic fluid. During gestation, plasma peptide concentrations did not change in cows. Likewise, fetal plasma concentrations of cholecystokinin, somatostatin, secretin and vasoactive intestinal polypeptide showed no variation while those of gastrin, pancreatic polypeptide and gastric inhibitory polypeptide increased during the last 6 months. Peptide levels in the fetus were higher than or equal to maternal concentrations. At 8-9 months of gestation, gastrin, CCK, secretin and somatostatin concentrations in amniotic fluid were lower than those measured in fetal gastric content and in maternal and fetal plasma. Therefore, a substantial endogenous endocrine production of regulatory peptides by the fetus probably exists as early as the third month of gestation, accompanied by a release into the lumen of the gut.     

Effect of Tityus serrulatus scorpion toxin on serum gastrin levels in anaesthetized rat

Scorpion toxin induces gastric secretion of acid and pepsin in rats. These effects seem to be mediated by the release of acetylcholine and histamine. However, the role of gastrin in the scorpion-toxin-induced gastric secretion is unknown. We describe the effects of the T1 fraction purified from Tityus serrulatus scorpion venom on serum and on antral tissue gastrin levels in anaesthetized rats. Gastrin levels in serum and in the antral mucosa were measured before and at intervals 5, 15, 30, 60, 90 up to 120 min after the intravenous injection of saline or the T1 fraction of scorpion venom (0.25 mg/kg) into anaesthetized rats. Antral G-cells were submitted to immunocytochemistry and electron microscopy. The data on gastrin were correlated with the gastric juice volume, and the acid and pepsin output increases induced by toxin. Scorpion toxin induced a significant increase in volume, acid output and pepsin output of gastric juice and gastrin serum levels 15-60 min after injection. Simultaneous measurements of antral gastrin levels did not show significant effects. The number of dense, intermediate and empty granules per microm(2) in the cytoplasm of antral G-cells was not significantly changed 60 min after saline or toxin injection. Scorpion toxin significantly increased serum gastrin; levels in rats.     

The effects of cysteamine on the upper gastrointestinal tract of children with cystinosis

The purpose of this study was to evaluate the effects of cysteamine on gastric acid output and serum gastrin levels in children with nephropathic cystinosis. We studied four children with nephropathic cystinosis receiving a dose of free base cysteamine of 14.35 mg/kg four times a day (range 12.30-18.80 mg/kg). Gastric acid was measured for the hour before and after administration of the medication. Serum gastrin levels were obtained at 0, 30, 60, and 90 min following the medication. Gastrointestinal anatomy was evaluated by endoscopy and biopsy. Following administration of the medication, all subjects showed an increase in gastric acid output. Mean acid output increased from 0.79 to 2.22 mEq/h. Mean gastric acid output adjusted for body weight increased from 0.03 to 0.09 mEq/kg per hour. Following administration of the medication, all subjects showed an increase in serum gastrin. The mean increase above the base value was 38.3 pg/dl. Two of the four subjects demonstrated visual and histological evidence of inflammation. Cysteamine has a marked effect on gastric acid production and serum gastrin, even at the dose used in children with nephropathic cystinosis. The clinical effect of this acid production is unknown but may be significant.     

The vagus

The surgical physiology of the vagus is reviewed with respect to vagotomy in the treatment of duodenal ulcer. All types of vagotomy (truncal, selective gastric, or proximal gastric) produce similar reduction in acid secretion and comparable elevation in serum gastrin. The evidence is mounting that the vagus may have opposing influences on gastrin release: stimulation and inhibition. Division of only the extragastric vagal branches leads to withdrawal of an inhibitory mechanism rendering the denervated stomach more sensitive to the action of gastrin. The loss of this vagally controlled inhibitory mechanism, rather than more meticulous dissection, may explain the higher incidence of more complete vagotomies in selective than in truncal vagotomy. Proximal gastric vagotomy may be the ideal elective operation yet devised for duodenal ulcer. It does, however, cause elevation in serum gastrin and more than 90 per cent of patients after this operation will have positive insulin test in two to four years. This is higher than the positivity seen with truncal vagotomy. Results of controlled trials are needed before this operation becomes fully established.     

Effect of intrajejunal fat on meal-stimulated acid and gastrin secretion in man

The effect of intrajejunal fat infusion on meal-stimulated gastric acid and gastrin secretion was studied in 8 healthy volunteers. Intrajejunal fat significantly reduced the acid response to a meal, measured by intragastric titration, as compared to intrajejunal infusion of saline. While serum gastrin concentrations rose from fasting levels to a constant plateau after the meal when saline was infused, fat infusion resulted in a transitory decrease in serum gastrin concentration followed by a significant increase. It is concluded that inhibition of gastrin release only plays a minor role, if any, in the observed fat-induced jejuanl inhibition of meal-stimulated acid secretion.     

Association between serum gastrin levels, gastric acid secretion and age in early gastric cancer

This study evaluated the effect of gastric acid secretion and serum gastrin response on tumor differentiation for early gastric cancer according to patients' age. We investigated the association between serum gastrin levels, gastric acid secretion and the histologic types of 335 early gastric carcinomas limited to the mucosal and submucosal layers in comparison with 450 gastric and 197 duodenal ulcers. The preoperatively examined basal acid output, maximal acid output and peak acid output after administration of tetragastrin and serum gastrin levels before and after ingestion of a test meal were determined. Patients with differentiated cancer and duodenal ulcer showed a significant negative correlation between gastric acid secretion and age, while the former group also had a significant positive correlation between serum gastrin levels and age. On the other hand, patients with undifferentiated cancer did not show any such correlation between gastric acid and age, but showed a significant positive correlation between serum gastrin, integrated gastrin response and age. Patients with gastric ulcer did not show any such correlations. These data suggest that both low acid secretion and endogenous hypergastrinemia, especially in the elderly, may play an important role in differentiated and undifferentiated gastric carcinomas.     

Arthroscopic-assisted allograft anterior cruciate ligament reconstruction in patients with symptomatic arthrosis

BACKGROUND: Antral motility and the hormone cholecystokinin (CCK) are major determinants of the rate of gastric emptying. The relation between CCK and antral neurons in regulating gastric emptying is uncertain. Benzalkonium chloride (BAC) causes selective lesions in gut myenteric neurons after serosal application. AIM: To develop a model of antral denervation using BAC to enable the study of the relation between CCK and antral neurons in regulating gastric emptying. METHODS: BAC, vehicle or the afferent neurotoxin capsaicin were applied to the serosal surface of the rat antrum or corpus; neurochemical markers of intrinsic and afferent neurons were detected by using immunohistochemistry and radioimmunoassay. Gastric retention of solids was determined after fasting, and emptying of liquids was measured in rats with gastric fistulae. RESULTS: In BAC treated rats radioimmunoassay of tissue extracts revealed a dose related specific loss of gastrin releasing peptide, substance P, and vasoactive intestinal polypeptide immunoreactivities from the treated region, and immunohistochemistry revealed loss of the neuronal marker PGP 9.5 and the afferent neuropeptide calcitonin gene related peptide (CGRP). Adjacent untreated regions were unaffected by BAC, with the exception that CGRP was depleted in both corpus and antrum after antral treatment. After antral BAC treatment fasted rats retained solids for over 48 hours. Moreover, in antrally denervated rats with gastric fistulae, the emptying of saline, acid and peptone was delayed substantially. The CCK dependent inhibition of gastric emptying of peptone was preserved after antral treatment with BAC. CONCLUSIONS: Serosal BAC causes lesions in the innervation of the treated region of the stomach. The innervation of the antrum is essential for normal emptying of both liquids and solids, but the inhibition of gastric emptying produced by CCK is not dependent on antral neurons.     

Hypoxia inhibits gastric emptying and gastric acid secretion in conscious rats

This study examines the effects of hypoxia in the gastric function in conscious rats which adapted to a meal-feeding schedule, that allowed free access to a high protein (HP) diet (550 g casein/kg diet, Exp.1,2 and 4), a normal protein (NP) diet (200 g casein/kg diet, Exp.3) or a nonpurified rat (NPR) diet (Exp. 5 and 6) for 4 h every day for 2 wk. In Exp. 1, after 4 h of consuming the HP diet, rats were exposed to 7.6 or 10.5% O2 normobaric hypoxia. Hypoxia delayed the excretion of urinary urea for 12 h. In Exp.2 and 3, when rats were exposed to 7.6%O2 after 4 h of consuming the HP diet and exposed to 10.5% O2 after 4 h of consuming the NP diet, respectively, a significant delay in gastric emptying was found in the hypoxic rats. In Exp. 4, when rats were exposed to 7.6 O2 hypoxia after 4 hr of eating the HP diet, the plasma gastrin concentration in the 7.6% O2 hypoxic rats was 2.3-fold that of the normoxic rats after 6 h of hypoxia. Furthermore, when rats that did not consume any HP diet on the day of the experiment were exposed to 7.6 or 10.5% O2 hypoxia, the plasma gastrin concentration was higher in both hypoxic groups than in the normoxic group after 3 and 6 of hypoxia. In Exp. 5, rats that were not fed the NPR diet on the day of study were exposed to 7.6 or 10.5% O2 hypoxia for 3 h after pylorus ligation. Hypoxia inhibited the secretion of gastric acid and elevated the plasma gastrin concentration. In Exp. 6, unfed rats that had been consuming the NPR diet were exposed to 7.6% O2 hypoxia for 3 h after pylorus ligation and were orally administered HCl. The rise of the gastrin concentration due to hypoxia was completely inhibited by oral HCl. These results demonstrate that hypoxia inhibits gastric emptying and gastric acid secretion and that the inhibitory effect of hypoxia on gastric acid secretion stimulates gastrin release through positive feedback regulation.     

Transplantation of hepatocytes for prevention of intracranial hypertension in pigs with ischemic liver failure

BACKGROUND: How Helicobacter pylori infection affects gastric acid secretion is still unclear. METHODS: Gastric juice pH, ammonia concentration in gastric juice, serum gastrin level, and grade of gastritis in accordance with the Sydney System were determined for patients with gastric ulcer (GU) and duodenal ulcer (DU) before and after treatment with lansoprazole and amoxicillin, and results were compared with those of H. pylori-negative controls. RESULTS: Scores for H. pylori density, atrophy, metaplasia, and activity of gastritis in the corpus were higher in patients with GU, especially those with proximally located GU, than in those with DU. Gastric juice pH was significantly higher in GU patients than in DU patients and controls. After H. pylori eradication, gastric juice pH and serum gastrin levels in both GU and DU patients were significantly decreased to control levels. In patients without eradication, no significant changes in these factors were observed. CONCLUSIONS: These findings suggest that H. pylori infection and gastritis in the corpus suppress acid secretion and increase gastric juice pH, resulting in hypergastrinemia, and that eradication of H. pylori normalizes acid secretion and serum gastrin levels.     

The effect of octreotide on gastric emptying at a dosage used to prevent complications after pancreatic surgery: a randomised, placebo controlled study in volunteers

BACKGROUND: Octreotide is used in many centres to prevent complications after pancreatic surgery. Delayed gastric emptying is a another complication occurring in around 30% of patients after pancreatoduodenectomy (PD) and causes prolonged hospital stay. The influence of octreotide on this complication is doubtful. AIMS: To assess the effect of octreotide, at the clinical dosage used after pancreatic surgery, on gastric emptying in healthy volunteers. SUBJECTS AND METHODS: Eight healthy male volunteers (mean age 22.5 years) participated in this double blind, placebo controlled study. On day 1 subjects received 100 micrograms of octreotide or placebo subcutaneously, three times daily and on day 2, one hour after the fourth injection, gastric emptying, postprandial cholecystokinin (CCK) release, and mouth to caecum transit time (MCTT) were measured. This protocol was repeated after one week, in a crossover design. On the test day subjects received a liquid test meal (1.57 MJ/300 ml) and gastric emptying measurements were performed with applied potential tomography, an non-invasive, validated technique which measures gastric emptying through impedance differences. From the gastric emptying curves, lag time, t50, and postlag emptying rate were measured. MCTT was measured using the hydrogen breath test. RESULTS: Lag time decreased from 29.6 (6.3) (mean (SEM)) to 12.2 (4.6) minutes (p < 0.05) during octretide treatment; t50 decreased from 87.8 (12.0) to 47.5 (8.2) minutes (p < 0.02) and there was a trend towards an increased postlag emptying rate (0.8 to 1.6% per minute; p = 0.07). MCTT increased from 150 (12.7) to 229 (17.9) minutes during octreotide treatment (p < 0.01). Octreotide suppressed postprandial CCK release (p < 0.05). CONCLUSIONS: MCTT was delayed by octreotide, suggesting impairment of small bowl treatment. Octreotide administered at the clinical dosage for pancreatic surgery accelerates gastric emptying, mainly by shortening the lag time. Suppression of postprandial CCK release may be involved in this process. Octreotide administration is therefore not a contributing factor in the pathogenesis of delayed postoperative gastric emptying after PD and might even play a role in preventing this complication.     

Developmental regulation of gastric somatostatin secretion in the sheep

Gastric somatostatin (SRIF) regulates gastric acidity by inhibiting gastric acid and gastrin secretion. SRIF secretion is increased by gastric acidity and also directly by regulators of gastric acid secretion such as gastrin. This direct effect has not been described in the developing animal, nor have the roles of intermediaries such as histamine and gastric acidity been defined. The present study aimed to establish the regulatory role of gastrin and histamine during development on SRIF secretion and also to determine whether the effects of gastrin and histamine are independent of gastric pH. Pentagastrin and histamine were infused on separate occasions into fetal sheep, newborn lambs, and 28-day-old lambs. To determine the roles of endogenous histamine and gastric pH, ranitidine (a histamine-2 receptor antagonist) and omeprazole (a H+/K+ ATPase inhibitor) were coinfused with the agonists. Plasma SRIF and gastrin concentrations were measured by RIA. Pentagastrin stimulated SRIF secretion in the fetus after 131 days of gestation (term is 147 days), whereas stimulation by histamine was effective only after birth. The SRIF stimulatory effect of pentagastrin in 28-day-old lambs was abolished by ranitidine, which also reduced this effect in the adult sheep. This inhibitory effect of ranitidine was shown to be a result of blockade of stimulatory H2 receptors, because in the adult blockade of acid secretion with omeprazole failed to attenuate the response of histamine. These results indicate that in the fetus, gastrin receptors, but not histamine receptors, are functionally involved in the stimulation of SRIF secretion. After birth, both gastrin and histamine stimulate SRIF, but the effect of gastrin is mediated at least in part by the release of endogenous histamine. These responses occur independently of changes in gastric acidity, supporting the concept of a direct negative feedback between SRIF and gastrin.     

Preoperative and postoperative colonoscopy for colorectal carcinoma

A patient with documented ZE syndrome responded to intravenous magnesium infusion by increased gastric acid output and increased serum gastrin concentration. A patient with acid hypersecretion but no gastrinoma had no substantial alteration in acid output or serum gastrin concentration following magnesium administration. This suggests that magnesium caused gastrin to be released from a gastrinoma.     

Codon 219 Lys allele of PRNP is not found in sporadic Creutzfeldt-Jakob disease

OBJECTIVE: To determine the prevalence of hypergastrinemia in cats with naturally developing chronic renal failure (CRF) and the correlation between gastrin concentration in plasma and severity of CRF. DESIGN: Cohort study. ANIMALS: 30 cats with naturally developing CRF and 12 clinically normal control cats. PROCEDURE: Gastrin concentrations in plasma were determined by double-antibody radioimmunoassay of blood samples obtained from cats after food was withheld 8 hours. Concentrations were compared, using a nonparametric Kruskal-Wallis ANOVA. RESULTS: 18 cats with CRF had high gastrin concentrations (median, 45 pg/ml; range, < 18 to > 1,333 pg/ml), compared with those for control cats (< 18 pg/ml). Prevalence of hypergastrinemia increased with severity of renal insufficiency. Three of 9 cats with mild CRF, 6 of 11 cats with moderate CRF, and 9 of 10 cats with severe CRF had high gastrin concentrations. Gastrin concentrations were significantly different between control cats and cats with CRF, regardless of disease severity. CLINICAL IMPLICATIONS: The potential role of high concentrations of gastrin on gastric hyperacidity, uremic gastritis, bleeding from the gastrointestinal tract, and associated clinical signs of hypergastrinemia (e.g., anorexia and vomiting) may justify use of histamine2-receptor antagonists or proton pump inhibitors to suppress gastric acid secretion in cats with CRF that have these clinical signs.