Expression and ligand binding of bombesin receptors in pulmonary and intestinal carcinoids

INTRODUCTION

Carcinoids are mainly found in the gastrointestinal (65%) and bronchopulmonary tract (25%). These neuroendocrine tumors secrete a wide range of bioactive peptides, including gastrin releasing peptide and neuromedin B, the mammalian analogs of bombesin. The purpose of this study was to investigate the quantity and localization of bombesin receptors in gastrointestinal and pulmonary carcinoids, and to reveal whether bombesin-like peptides (BLP) and their receptors are of any value in distinguishing pulmonary carcinoids from carcinoids of intestinal origin.

METHODS

Carcinoid tumors with pulmonary (no.=9) or intestinal (no.=15) localizations were analyzed by immunohistochemistry, autoradiography, and radioimmunoassay, to examine the presence of bombesin receptor subtypes and determine BLP levels in these tumors.

RESULTS

All 3 bombesin receptor subtypes (GRPR, NMBR, and BRS-3) were present on pulmonary and intestinal carcinoids by immunohistochemistry. In pulmonary carcinoids, low receptor ligand binding densities together with high and low BLP levels were found. Intestinal carcinoids showed predominantly high receptor ligand binding densities in combination with low BLP levels.

CONCLUSIONS

The expression of bombesin receptor subtypes is independent from the carcinoid tumor origin, and is therefore not recommended as a distinction marker, although carcinoids of pulmonary and intestinal origin possess different receptor binding affinities for bombesin and dissimilar BLP levels. The combined presence of bombesin and its receptors might suggest the presence of a paracrine or autocrine growth loop in carcinoids.

An overview of the current diagnosis and recent developments in neuroendocrine tumours of the gastroenteropancreatic tract: the diagnostic approach

Neuroendocrine tumours of the gastroenteropancreatic tract (GEP-NETs) comprise a group of very heterogeneous neoplasms, which are considered 'rare diseases'. Epidemiological studies on the incidence of GEP-NETs worldwide have reported a remarkable increase in the detection of these tumours. In a recent study, based on pathology reports (PALGA) to investigate the incidence of pancreatic and duodenal neuroendocrine tumours in the Netherlands from 1991 until 2009, we also noticed a significant increase in the incidence of these tumours. In particular, the incidence of non-functioning neuroendocrine tumours had significantly increased over this period. Remarkably, a substantial discrepancy was observed between the numbers of neuroendocrine tumours diagnosed in the clinical as opposed to the pathological setting, emphasising that these tumours provide a real diagnostic challenge. To improve the diagnosis of GEP -NET s, we advocate that these complex neoplasms should receive more specialised attention. In this mini-review we provide an overview of the current diagnostic approach to GEP-NETs, and add the recent developments in establishing the diagnosis of these tumours, in order to increase knowledge and awareness of GEP-NETs among clinicians and pathologists. Early detection in order to prevent morbidity from GEP-NETs is advocated.

Substance P receptor expression in patients with inflammatory bowel disease. Determination by three different techniques, i.e., storage phosphor autoradiography, RT-PCR and immunohistochemistry

Inflammatory bowel disease (IBD) is characterized by chronic intestinal inflammation accompanied by changes in motility. It is known that regulatory peptides like substance P (SP) are important pro-inflammatory peptides which are also involved in neuronal conduction. To get clues for new diagnostic and therapeutic approaches we describe the SP receptor (NK-1) distribution in IBD compared to control intestinal tissue, on mRNA and protein level by three complementary techniques. Autoradiography showed differences within the intestinal wall of control patients; mucosal binding was 17 fmol/g and muscular binding was significantly (p=0.01) higher (98 fmol/g). In inflamed specimens of patients with IBD mucosal SP binding was increased compared to controls (55+/-10 vs 18+/-4 fmol/g mucosa, p=0.002). However RT-PCR showed that the mRNA content of the NK-1 receptor in these samples was not increased. In non-inflamed samples of patients with Crohn's disease (CD) and ulcerative colitis (UC) SP binding was similar as in controls, while mRNA was significantly decreased in CD patients (0.7+/-0.02 vs 4.4+/-0.7, p=0.01) but not in UC patients (4.4+/-0.7 vs 4.1+/-1.4). Immunohistochemistry identified a broad spectrum of NK-1 receptor locations in control intestine. No aberrant expression in IBD was found. This study showed that although there was no difference in location of the SP receptors in IBD patients versus controls, the quantity of SP binding was significantly increased in the inflamed mucosa of IBD patients, while the mRNA level was not increased. Further a difference in mRNA level between non-inflamed tissue of CD and UC patients was shown, with mRNA in CD being lower. These changes in SP receptor expression during chronic inflammation suggest that SP receptors are a potential target for therapeutic regulation of the inflammatory response.

The 13carbon urea breath test for the diagnosis of Helicobacter pylori infection in subjects with atrophic gastritis: evaluation in a primary care setting

BACKGROUND

(13)Carbon urea breath testing is reliable to detect current infection with Helicobacter pylori but has been reported to be of limited value in selected patients with atrophic body gastritis or acid-lowering medication.

AIM

To evaluate the accuracy of (13)carbon urea breath testing for H. pylori detection in 20 asymptomatic patients with histologically confirmed atrophic body gastritis in a primary care setting.

METHODS

(13)Carbon urea breath testing and serology were compared with H. pylori culture of a corpus biopsy as reference test.

RESULTS

All tests were in agreement in 12 patients, being all positive in six and all negative in six. One patient was positive for serology and culture but negative for (13)carbon urea breath testing, five patients had only positive serology and two patients had only positive (13)carbon urea breath testing. (13)Carbon urea breath testing showed an accuracy with culture of 85% and anti-H. pylori serology with culture of 75%. (13)Carbon urea breath testing carried out in patients with positive serology showed an accuracy of 92%. Receiver operating characteristic curve analysis of (13)carbon urea breath testing shows optimal discrimination at the prescribed cut-off value.

CONCLUSIONS

(13)Carbon urea breath testing can be used as diagnostic H. pylori test in asymptomatic patients with atrophic body gastritis, preferably in addition to serology, to select subjects for anti-H. pylori therapy.

Gastrin releasing peptide receptor expression is decreased in patients with Crohn's disease but not in ulcerative colitis

BACKGROUND

Gastrin releasing peptide (GRP) and neuromedin B are bombesin (BN)-like peptides involved in regulating motility and inflammation in the gastrointestinal tract, which may be useful in treating inflammatory bowel disease (IBD). Three bombesin-like peptide receptors have been reported, but no studies have investigated their localisation in normal and inflamed human intestine.

AIM

To localise and characterise BN receptors in normal intestine and to see whether this is modified in IBD.

METHODS

Full thickness intestinal tissue samples were collected from 13 patients with Crohn's disease (CD), 11 with ulcerative colitis (UC), and 19 controls. BN receptor expression was characterised and quantified with storage phosphor autoradiography using BN, GRP, neuromedin B, and the synthetic analogue BN(6-14) as ligands.

RESULTS

Only BN receptor type 2 (high affinity for GRP) was present in intestinal tissue. Minimal BN binding was detected in the mucosa. In normal colonic smooth muscle, mean BN binding was 336 fmol/g tissue in longitudinal muscle, including the myenteric plexus, and 71 fmol/g in circular muscle. In CD, colonic smooth muscle BN binding was significantly decreased (longitudinal muscle, 106; circular muscle, 19 fmol/g), in contrast to UC (377 and 62 fmol/g, respectively). In CD, a small (not significant) decrease was seen in ileal muscle compared with controls (111 v 169 and 18 v 32 fmol/g tissue for longitudinal and circular muscle, respectively).

CONCLUSIONS

Only the GRP receptor is expressed in human intestine; expression is highest in longitudinal muscle and myenteric plexus of the colon. Expression is decreased in inflamed and non-inflamed colon of CD, but not in UC.

Faecal elastase-I: helpful in analysing steatorrhoea?

BACKGROUND

The faecal elastase-1 test (FE-1) is considered easy to perform and sensitive to detect severe and moderate exocrine pancreatic insufficiency. However, little information is available on the specificity of this test in the analysis of steatorrhoea. Our aim was to evaluate the clinical value of FE-1 in the analysis of patients sent in for faecal fat determination.

METHODS

Stool samples were collected over 24 hours in 40 healthy controls and 119 patients: 58 patients with chronic pancreatitis and 61 nonpancreatic disease patients with chronic diarrhoea. Faecal fat excretion was determined and FE-1 was measured using a commercially available ELISA kit, which employs two monoclonal antibodies to bind to two distinct epitopes of human pancreatic elastase-1.

RESULTS

Faecal elastase-1 test shows good reproducibility. The test lacks sensitivity in detecting exocrine pancreatic insufficiency and chronic pancreatitis (68 and 59%, respectively). However, it is specific with respect to differentiating pancreatic from nonpancreatic causes in patients with steatorrhoea.

CONCLUSION

FE-1 lacks sensitivity to detect chronic pancreatitis. It can serve as a simple, noninvasive method to determine the aetiology of steatorrhoea.

The effect of motilin on the rectum in healthy volunteers

AIMS

The role of motilin in the regulation of upper gastrointestinal (GI) motility is well defined. However, little is known about the effects on the distal GI tract. To investigate the effect of exogenous motilin on rectal function, barostat measurements in the rectum were performed and lower abdominal symptoms were scored.

METHODS

Eight fasted, healthy volunteers were infused intravenously with synthetic motilin or placebo over 90 min in a double-blind, randomized, cross-over design. Rectum volume was measured with a barostat device during constant pressure and during isobaric distensions. Lower abdominal symptoms were scored by visual analogue scales. Plasma motilin concentrations were measured by radioimmunoassay.

RESULTS

Baseline rectum volumes were similar between treatments: 185 +/- 62 mL (motilin) and 136 +/- 41 mL (placebo). During the constant pressure procedure, motilin increased rectum volume [area under the effect curve (AUEC)] by 6%[95% confidence interval (CI) -3, 16] of baseline, compared with placebo. During isobaric distensions motilin increased rectum volume (AUEC) by 43 mL (95% CI 0.4, 85; P < 0.05) and compliance by 10 mL mmHg-1 (95% CI 0.3, 20; P < 0.05) relative to placebo. Motilin did not induce changes in the sensation of rectal feelings.

CONCLUSION

Exogenous motilin increased rectal compliance in healthy volunteers, without affecting rectal sensations.

The serological gastric biopsy: a non-endoscopical diagnostic approach in management of the dyspeptic patient: significance for primary care based on a survey of the literature

BACKGROUND

Measurement of the serum concentration of the secretory products of the gastric mucosa, pepsinogen A (PgA), pepsinogen C (PgC) and gastrin is called the serological gastric biopsy. Additional measurement of Helicobacter pylori antibodies and antibodies to parietal cells and intrinsic factor supports the non-invasive diagnostic value of the serum markers. In many clinical studies, the diagnostic potential of the serum markers in predicting the topography and severity of gastric mucosal disorders has been established. The aim was to assess the diagnostic value of the serological gastric biopsy for primary care.

METHOD

Survey of the literature.

RESULTS

The cell-physiological background of the serological gastric biopsy, the interpretation of the outcome of serum markers and the relation of these parameters to various gastric mucosal disorders are described. Measurement of PgA is a reliable way to discriminate between mucosal gastritis and functional dyspepsia. PgA is raised in duodenal, gastric and pyloric ulcer even though gastrin is normal. Both PgA and gastrin are raised in renal insufficiency and the Zollinger-Ellison syndrome. A low PgA is indicative of mucosal atrophy and a good indicator for gastric hypoacidity. An additional low PgA:C ratio is indicative of atrophic gastritis or extensive intestinal metaplasia of the stomach. A hypopepsinogenaemia can also be an alarm symptom for gastric cancer. A low PgA and a high gastrin is indicative of corpus atrophy.

CONCLUSION

In primary care, the serological gastric biopsy might be a feasible and appropriate diagnostic method for management of the dyspeptic patient. Further research in general practice has to be done to validate the predictive value of the serological gastric biopsy and to define a diagnostic strategy.

Ratio between serum IL-8 and pepsinogen A/C: a marker for atrophic body gastritis

BACKGROUND AND AIMS

Elevated serum gastrin and a low pepsinogen A/C ratio are well-recognized markers for atrophic body gastritis (ABG). We have shown that the presence of body atrophy is also associated with elevated serum pro-inflammatory cytokines. This study tested the hypothesis that serum cytokines provide additional information to gastrin and pepsinogens in screening for ABG.

METHODS

Two hundred and twenty-six consecutive patients were investigated on referral for upper gastrointestinal endoscopy: 150 were patients with gastro-oesophageal reflux disease, receiving acid inhibitory medication either with proton pump inhibitors (n = 113) or with histamine2-receptor antagonists (n = 37), and 76 were nontreated controls, who had normal endoscopic findings. Gastric mucosal biopsies were sampled for histological examination (Sydney classification). Serum samples were analyzed for gastrin, chromogranin A (CgA), and pepsinogens A and C by RIA, and for the interleukins (IL)-1beta, IL-6, and IL-8 by ELISA.

RESULTS

Subjects with ABG had significantly higher serum gastrin (P < 0.01) and serum CgA (P < 0.01) levels and significantly lower pepsinogen A/C ratios (P < 0.001) than those without ABG. Additionally, serum IL-1beta, IL-6 and, especially, IL-8 levels were significantly higher in the subjects with than in those without ABG (P < 0.0001, for all cytokines). To optimize the detection of body atrophy we defined the ABG index: the ratio between the simultaneously measured IL-8 and pepsinogen A/C. The area under the ROC curve for the ABG index was significantly greater than that for serum gastrin and for serum pepsinogen A/C alone (0.91 +/- 0.029 vs. 0.72 +/- 0.042, and vs. 0.83 +/- 0.031, P = 0.018 and P = 0.049). Using the ABG index at a cut-off value of 1.8 pg mL-1, 91% of the cases were classified correctly.

CONCLUSIONS

The ratio between serum IL-8 and pepsinogen A/C accurately predicts the presence of ABG. We therefore propose the ABG index as a noninvasive screening test for ABG in population-based studies.

Gall bladder dysmotility: a risk factor for gall stone formation in hypertriglyceridaemia and reversal on triglyceride lowering therapy by bezafibrate and fish oil

BACKGROUND AND AIM

The aim of this study was to unravel the mechanisms responsible for the increased risk of gall stone disease in hypertriglyceridaemia (HTG) and to compare the effects of triglyceride lowering therapy by bezafibrate and fish oil on determinants of cholelithiasis (biliary lipid composition and gall bladder motility) in HTG patients.

PATIENTS AND METHODS

Gall bladder motility (ultrasonography) was studied postprandially and during infusion of cholecystokinin (CCK). Determinants of cholelithiasis and serum lipids were compared between nine HTG patients and 10 age, sex, and body mass index matched normolipidaemic controls. The effects of bezafibrate and fish oil in HTG patients were studied in a randomised cross over trial.

RESULTS

HTG patients showed 14-fold higher serum triglyceride (TG) levels than controls. Biliary lipid composition, fasting gall bladder volumes, and CCK levels did not differ between HTG patients and controls. Gall bladder emptying was reduced in HTG patients compared with controls during CCK infusion (-22%) as well as in response to a meal (-37%; both p<0.001). Postprandial CCK levels were significantly higher in HTG patients. Both bezafibrate and fish oil reduced serum TG levels (-68% and -51% v baseline, respectively; both p<0.01). Fasting CCK levels were not affected whereas CCK induced gall bladder emptying increased during bezafibrate (+29%; p<0.001) and tended to increase on fish oil therapy (+13%; p=0.07). Postprandial gall bladder motility improved on bezafibrate and fish oil (+47 and +25% v baseline, respectively; both p<0.02) at least partly due to increased gall bladder sensitivity to CCK (both p<0.05 v baseline). Bezafibrate but not fish oil increased the molar ratio of cholesterol to bile acids (+40%; p</=0.05) but no effects on cholesterol saturation index were seen with either treatment.

CONCLUSIONS

We suggest that impaired gall bladder motility occurs in HTG patients due to decreased sensitivity to CCK, which may add to the enhanced risk of gall stone disease in HTG patients. Triglyceride lowering therapy by both fish oil and bezafibrate improve gall bladder dysmotility without adversely affecting biliary cholesterol saturation.

The effect of equicaloric medium-chain and long-chain triglycerides on pancreas enzyme secretion

It has been shown previously that medium chain triglycerides (MCT) do not affect gallbladder emptying and cholecystokinin (CCK) release. The effect of MCT on exocrine pancreas secretion in humans is unknown. We have compared the effect of enteral administration of MCT versus long chain triglycerides (LCT) on exocrine pancreatic secretion. Eight healthy subjects (three female, five male; mean age 22 +/- 1.9 years) participated in two experiments, performed in random order. Duodenal contents, obtained by aspiration, were used to calculated the output of pancreatic enzymes and bilirubin. An equicaloric amount of either MCT or LCT (2 kcal min-1) oil was continuously administered in the proximal jejunum for 2 h. Gallbladder volume was measured by ultrasonography and blood samples were drawn for determination of CCK. The experiments consisted of 1 h basal secretion, 2 h of continuous oil administration and 1 h poststimulation. During the LCT feeding the pancreatic enzyme secretion, bilirubin output, gallbladder emptying and CCK release increased significantly (P < 0.05) over basal levels. MCT had no effect on pancreatic enzyme secretion nor gallbladder emptying or CCK release. We conclude that enteral administration of MCT in the proximal jejunum does not stimulate exocrine pancreatic secretion nor gallbladder contraction or CCK release, in contrast to an equicaloric amount of LCT.

Exogenous motilin affects postprandial proximal gastric motor function and visceral sensation

Our aim was to investigate the effect of motilin on postprandial proximal gastric motor and sensory function in healthy volunteers. Ten fasted, healthy volunteers were infused intravenously with synthetic motilin or placebo over 90 min. A liquid meal (200 ml) was ingested within 2 min at the start of the infusion. Proximal gastric volume was measured with a barostat device. Abdominal symptoms were scored by visual analog scales. Plasma motilin concentrations were measured using RIA. Endogenous motilin levels were not affected by meal ingestion. After meal intake, gastric relaxation was similar for motilin and placebo. After postprandial relaxation, motilin resulted in a faster return of gastric volume to baseline (P = 0.007). Motilin significantly increased postprandial feelings of nausea (P = 0.03) and tended to increase abdominal pain and abdominal tension. In conclusion, after normal postprandial gastric relaxation, motilin accelerated the return of gastric volume to baseline. In addition, motilin increased postprandial feelings of nausea.

Pancreatic polypeptide secretion in patients with chronic pancreatitis and after pancreatic surgery

AIM

We investigated polypeptide (PP) secretion under basal conditions, in response to bombesin infusion and to meal ingestion in patients with chronic pancreatitis (CP) and patients after different types of pancreatic surgery.

METHODS

Included were patients with CP without (n = 20) and with (n = 30) exocrine pancreatic insufficiency, patients after duodenum preserving resection of the head of the pancreas (DPRHP; n = 20), after Whipple's procedure (n = 19), following distal pancreatectomy (DP; n = 12), and healthy controls (n = 36).

RESULTS

In CP patients basal and bombesin stimulated PP levels were significantly (p<0.01) reduced compared to controls only when exocrine insufficiency was present. Meal-stimulated PP secretion was significantly (p<0.01-0.05) reduced in CP patients both with and without exocrine insufficiency. Plasma PP peak increments after bombesin and meal ingestion correlated significantly with exocrine function. Basal PP, meal, and bombesin-stimulated PP secretion had low sensitivities of 22%, 42%, and 60% respectively, in detecting chronic pancreatitis. In patients after pancreatic surgery that included pancreatic head resection (DPRHP or Whipple operation) basal and stimulated PP secretion were significantly (p<0.01-0.05) reduced.

CONCLUSION

Basal and meal or bombesin-stimulated PP levels are significantly reduced in patients with CP only when exocrine insufficiency is present. Determination of plasma PP levels has low sensitivity and is not useful in detecting chronic pancreatitis without exocrine insufficiency. In patients after pancreatic surgery, PP secretion is dependent on the type of operation (head vs tail resection).

Dose-related effects of motilin on proximal gastrointestinal motility

AIM

To assess non-invasively the dose-response relations for the effects of exogenous motilin on antrum contraction frequency, gall-bladder volume and gastric myoelectrical activity.

METHODS

In a double-blind, randomized, placebo-controlled, five-way crossover study, 10 fasted healthy volunteers were infused intravenously with synthetic human motilin (0.5, 1, 2 and 4 pmol x min/kg) or placebo for 60 min. Gall-bladder volume and antrum contractions were assessed by ultrasonography and gastric myoelectrical activity by electrogastrography. Motilin concentrations were measured using a radioimmunoassay.

RESULTS

Baseline plasma motilin levels (60 pmol/L) were similar for all treatments. Motilin levels increased upon the start of infusion and rapidly returned to baseline after cessation of the infusion. At motilin doses of 2 and 4 pmol.min/kg, the antrum contraction frequency was significantly augmented, with maximum differences of two contractions per 2-min interval compared to placebo, while no changes in gastric myoelectrical activity were observed. Changes in gall-bladder volume were not significantly different for any of the motilin doses compared to placebo.

CONCLUSIONS

Motilin increased antrum contraction frequency, whereas no effect on gastric myoelectrical activity was observed. Antrum contraction frequency appears to be a useful biomarker for motilin efficacy, and motilin doses of 2 and 4 pmol x min/kg were equally effective.

Serum chromogranin A as a screening test for gastric enterochromaffin-like cell hyperplasia during acid-suppressive therapy

BACKGROUND

Serum chromogranin A (CgA), a marker of neuroendocrine neoplasia, increases during profound gastric acid inhibition, possibly reflecting the trophic effect of gastrin on the enterochromaffin-like (ECL) cells.

AIMS

This study investigated the clinical value of serum CgA as a screening test for gastric fundic enterochromaffin-like (ECL) cell hyperplasia during acid-suppressive therapy.

METHOD

A consecutive series of 230 dyspeptic patients referred for upper gastrointestinal endoscopy was investigated in a cross-sectional design. They were 154 patients on continuous medium-term (6 weeks to one year) or long-term (longer than one year) acid inhibition with either proton pump inhibitors (PPIs, n = 117) or histamine2-receptor antagonists (H2RAs, n = 37) for gastro-oesophageal reflux disease, and 76 nontreated subjects, with normal endoscopic findings (control group). Fasting blood samples were analysed for gastrin and CgA. Gastric biopsy specimens (oxyntic mucosa) were examined for histological evaluation of gastritis (Sydney classification) and of ECL cell hyperplasia (Solcia classification).

RESULTS

Serum CgA levels correlated positively with serum gastrin, following a quadratic function (r = 0.78, P < 0.0001). Elevated serum CgA values during long-term acid inhibition correlated with the presence and severity of fundic ECL cell hyperplasia. Multivariate analysis identified hypergastrinaemia (P < 0.0001), duration of acid inhibition (P < 0.0001), H. pylori infection (P = 0.008), ECL cell hyperplasia (P = 0.012), and body gland atrophy (P = 0.043) as independent predictors of elevated serum CgA. In subjects on long-term acid inhibition (n = 123), serum CgA was equally sensitive but more specific than serum gastrin for the detection of ECL cell hyperplasia (sensitivity, 91.3% for both; specificity, 73% vs. 43%, P < 0.0001).

CONCLUSIONS

During long-term gastric acid inhibition, serum CgA levels reflect the presence and severity of fundic ECL cell hyperplasia. Serum CgA is therefore a useful screening test for gastric ECL cell proliferative changes within this context.

Effect of somatostatin on postprandial gallbladder relaxation

Although the inhibitory effect of somatostatin (SST) on gallbladder contraction is well known, the influence of SST on gallbladder motility during the late postprandial or relaxation phase has not been studied. We therefore investigated the effect of SST on gallbladder relaxation and gut hormone release during the late postprandial phase. Eight healthy volunteers participated in two experiments performed in random order during continuous infusion of either SST or saline (placebo) starting 2 h after meal ingestion. At regular intervals, gallbladder volumes were measured (ultrasonography) and blood samples were taken for determination of plasma cholecystokinin (CCK), pancreatic polypeptide (PP), peptide YY (PYY) and neurotensin levels (radioimmunoassay). Postprandial gallbladder contraction was similar in both experiments: 68 +/- 4% vs. 66 +/- 4%. During SST infusion, postprandial gallbladder contraction was significantly (P<0.01) reduced (2874 +/- 813% *240 min) compared with saline (9391 +/- 1595% *240 min). Plasma CCK, PP, PYY and neurotensin levels were in the same range in the early postprandial phase but were significantly reduced during SST infusion compared with placebo (late postprandial phase). Plasma levels of CCK correlated with gallbladder volumes during both the contraction and relaxation phase (r=0.68, P=0.01 and r=0.61, P=0.008, respectively). SST enhances gallbladder relaxation and reduces hormone secretion in the late postprandial phase. The results point to an association between CCK and gallbladder volume not only during the postprandial contraction phase but also during the relaxation phase.

Effect of intraduodenal and intravenous amino acids on proximal gastric motor function in man

The present study was performed to investigate the effect of amino acids during the intestinal and postabsorptive phase of digestion on proximal gastric motor function measured with an electronic barostat. Eight healthy volunteers participated in three experiments performed during continuous infusion of: (1) intravenous and intraduodenal saline, (2) intraduodenal amino acids, and (3) intravenous amino acids. Both intraduodenal and intravenous amino acids induced gastric relaxation and increased gastric compliance. Only during intraduodenal amino acids did plasma CCK levels increase significantly. Correlation between intragastric volume measurements (with pressure set at MDP + 2 mm Hg) and plasma CCK levels was 0.90 (P < 0.001) during the early intestinal phase. Relaxation of the proximal stomach is related to plasma CCK in the early intestinal phase, whereas in the postabsorptive phase of amino acids other mechanisms play a role in proximal gastric relaxation.

Proximal and distal gut hormone secretion in slow transit constipation

BACKGROUND

It has been suggested that slow transit constipation might be part of a panenteric disorder. Gastrointestinal peptides are involved in regulation of motility.

DESIGN

In the present study we have evaluated whether plasma levels of proximal and distal gut hormones in the fasting state, and for 120 min after a solid meal in 29 patients with slow transit constipation are different from those obtained from 29 healthy controls. Plasma levels of the gut hormones cholecystokinin, gastrin, pancreatic polypeptide, motilin, neurotensin and peptide YY were determined using sensitive radioimmunoassays. In the patient group, oro-caecal transit time was determined by means of the hydrogen breath test on a separate test day. The results of transit were related with postprandial hormone secretion.

RESULTS

Fasting plasma levels of cholecystokinin and pancreatic polypeptide were significantly (P < 0.05) increased in constipated patients. Postprandially, secretion of pancreatic polypeptide and cholecystokinin was significantly (P < 0.05) increased in the patients, while secretion of peptide YY was significantly (P < 0.05) reduced. Plasma motilin levels were not different between patients and controls. Altered postprandial hormone secretion was mainly observed in constipated patients with prolonged oro-caecal transit time.

CONCLUSIONS

In patients with slow transit constipation, fasting and postprandial secretion of proximal gut hormones apart from motilin is increased and of distal gut hormones decreased, especially in those with severely delayed intestinal transit.

Parietal cell protrusions and fundic gland cysts during omeprazole maintenance treatment

Parietal cell protrusion (PCP), swelling and bulging of parietal cells, has been observed in the oxyntic mucosa of patients receiving omeprazole. The frequency of this event and the underlying mechanisms remain to be clarified. As such, it is unknown whether there is a relation with either serum gastrin or Helicobacter pylori infection, and whether PCP predisposes to the development of fundic gland cysts (FGC). We therefore investigated the development of PCP and FGC in gastroesophageal reflux disease (GERD) patients treated with omeprazole and correlated findings to duration of therapy, gastrin, and H pylori infection. In a randomized, double-blinded study, GERD patients were evaluated by endoscopy with biopsy sampling for histology and culture at baseline, and after 3 and 12 months' therapy with omeprazole 40 mg daily. H pylori-positive patients were randomized to additional eradication therapy or placebo antibiotics at baseline. All histological slides were scored blinded for time and outcome of culture for the presence of PCP and FGC. Fasting serum samples from all visits were used for gastrin measurements. The prevalence of PCP increased during omeprazole therapy from 18% at baseline to 79% and 86% at 3 and 12 months (P < .001, baseline v both 3 and 12 months). The prevalence of FGC increased from 8% to 17% and 35% (P < .05, baseline v 12 months). The prevalence of PCP and FGC did not differ among the H pylori-positive and H pylori-negative patients at baseline (PCP 16% v 20% and FGC 7% v 8%, respectively). Whereas H pylori eradication did not significantly affect development of PCP (P = .7), FGC developed significantly more often in the H pylori-eradicated patients when compared with persistent H pylori-positive patients (P < .05). PCP development was related to serum gastrin rise during therapy. In conclusion, PCP occurs in most patients within the first months of omeprazole treatment and is related to increased gastrin levels. FGC develops more gradually and is enhanced by H pylori eradication.

The osmotic laxative magnesium sulphate activates the ileal brake

BACKGROUND

Alterations in gastrointestinal motility and hormone secretion, especially activation of the ileal brake, have been documented in malabsorption.

AIM

To investigate whether artificially-induced accelerated small intestinal transit activates the ileal brake mechanism.

METHODS

Eight healthy volunteers (four female, four male; age 21 +/- 3 years) participated in four experiments: (a) meal with either oral magnesium sulphate (MgSO4) or placebo; and (b) fasting with either oral MgSO4 or placebo. Antroduodenal motility was recorded by perfusion manometry. Duodenocaecal transit time was determined by the lactulose H2 breath test. Gall-bladder volume was measured by ultrasound at regular intervals, and blood samples were drawn for determination of cholecystokinin and peptide YY (RIA). Twenty-four hour faecal weight and fat excretion were determined.

RESULTS

MgS04 significantly accelerated duodenocaecal transit time and increased faecal fat and weight in all subjects. MgSO4 significantly delayed the reoccurrence of phase III and affected antroduodenal motility during fasting but not after meal ingestion. Postprandial gall-bladder relaxation and postprandial peptide YY release were significantly increased during the MgSO4 experiment compared to placebo.

CONCLUSIONS

The osmotic laxative MgS04 accelerates intestinal transit both in the fasting and fed state. MgS04 activates the ileal brake mechanism only in the fed state, with peptide YY release and inhibition of gall-bladder emptying.

Antroduodenal motility in chronic pancreatitis: are abnormalities related to exocrine insufficiency?

In patients with chronic pancreatitis (CP) the relation among exocrine pancreatic secretion, gastrointestinal hormone release, and motility is disturbed. We studied digestive and interdigestive antroduodenal motility and postprandial gut hormone release in 26 patients with CP. Fifteen of these patients had pancreatic insufficiency (PI) established by urinary para-aminobenzoic acid test and fecal fat excretion. Antroduodenal motility was recorded after ingestion of a mixed liquid meal. The effect of pancreatic enzyme supplementation was studied in 8 of the 15 CP patients with PI. The duration of the postprandial antroduodenal motor pattern was significantly (P < 0.01) prolonged in CP patients (324 +/- 20 min) compared with controls (215 +/- 19 min). Antral motility indexes in the first hour after meal ingestion were significantly reduced in CP patients. The interdigestive migrating motor complex cycle length was significantly (P < 0.01) shorter in CP patients (90 +/- 8 min) compared with controls (129 +/- 8 min). These abnormalities were more pronounced in CP patients with exocrine PI. After supplementation of pancreatic enzymes, these alterations in motility reverted toward normal. Digestive and interdigestive antroduodenal motility are abnormal in patients with CP but significantly different from controls only in those with exocrine PI. These abnormalities in antroduodenal motility in CP are related to maldigestion.

Medium chain triglycerides activate distal but not proximal gut hormones

BACKGROUND AND AIMS

Compared to long chain triglycerides (LCT), medium chain triglycerides (MCT) are considered an attractive caloric source in malabsorptive diseases because of their favorable physico-chemical characteristics. The use of MCTis, however, limited by the occurrence of gastrointestinal symptoms such as diarrhoea. We have, therefore, investigated the effects of MCT and LCT on proximal (cholecystokinin; CCK) and distal (peptide YY; PYY) gut hormone secretion.

METHODS

Eight healthy volunteers participated in four experiments performed in random order during continuous intraduodenal administration for 360 min of a) saline (control); b) LCT15 mmol/h; c) MCT15mmol/h (equimolar); d) MCT 30 mmol/h (equicaloric). Plasma CCK and PYY were determined at regular intervals (radioimmunoassay). Duodenocecal transit (DCTT) was measured by lactulose H(2)breath test.

RESULTS

DCTT during LCT (105 +/- 11 min) was not significantly different from saline (111 +/- 10 min). Both low dose MCT (54 +/- 5 min) and high dose MCT (61 +/- 6 min) significantly accelerated DCTT (P< 0.05). Plasma CCK increased significantly (P< 0.05) during LCT but not during MCT or saline. PYY increased significantly (P< 0.05) not only during LCT, but also during low and high dose MCT but not during saline.

CONCLUSIONS

Intraduodenal MCTs a) accelerate intestinal transit; b) do not stimulate CCK release; c) but stimulate release of the distal gut hormone PYY. These results suggest that MCTs are not rapidly absorbed in the proximal gut but probably reach the ileocolonic region and stimulate PYY release.

Differential features of gastric cancer patients, either Helicobacter pylori positive or Helicobacter pylori negative

BACKGROUND

Helicobacter pylori infection is associated with an increased risk of gastric cancer. In Helicobacter pylori negative patients, factors different from those in Helicobacter pylori positive patients may be involved in gastric carcinogenesis.

METHODS

Thirty-nine recently diagnosed consecutive patients with gastric cancer were investigated. Gastric biopsies were obtained for detection of Helicobacter pylori (by immunohistochemistry), non-Helicobacter pylori flora (by modified Giemsa and culture) and histological assessment according to the Sydney classification by Haematoxylin-Eosin staining. In serum samples, Helicobacter pylori antibodies were determined by IgG enzyme-linked immunosorbent assay, IgA enzyme-linked immunosorbent assay, and Western blotting. Furthermore, serum gastrin, pepsinogen A and C and plasma chromogranin A were determined.

RESULTS

Helicobacter pylori was detected by immunohistochemistry in 53.8%, by IgG in 56.4%, by IgA in 33.3%, and by Western blotting in 74.4% of the 39 patients. Ten patients (25.6%) were negative by both histology and serology. Non-Helicobacter pylori flora was detected in 27 of the 39 patients (69.2%) with a similar frequency in Helicobacter pylori positive and negative patients. Helicobacter pylori positivity was found significantly more often in diffuse than intestinal type carcinoma patients (p < 0.05). Elevated gastrin levels and antrum-sparing atrophic gastritis were more frequent in Helicobacter pylori negative than in Helicobacter pylori positive patients (p < 0.05).

CONCLUSIONS

In 10 out of 39 gastric cancer patients, no evidence of previous or current Helicobacter pylori infection could be demonstrated. Non-Helicobacter pylori was found in 69.2% of patients regardless of the Helicobacter pylori status. Further studies are needed to establish the contribution of non-Helicobacter pylori flora as well as antrum-sparing atrophic gastritis with hypergastrinaemia to the development of gastric cancer.

Does jejunal feeding activate exocrine pancreatic secretion?

BACKGROUND

The upper small bowel is of pivotal importance for the stimulation of exocrine pancreatic secretion in response to a meal. We hypothesize that more distal delivery of nutrients into the small intestine will result in less activation of pancreatic secretion.

MATERIALS AND METHODS

Eight healthy subjects (3 male, 5 female; age 23 +/- 1 years) participated in two experiments, performed in random order. Subjects were intubated with a 4-lumen tube. Duodenal outputs of pancreatic enzymes and bilirubin were measured by aspiration using a recovery marker. The distal opening was used for continuous administration of a mixed liquid meal and located at either the ligament of Treitz or 60 cm further distally. Gallbladder volume was measured and blood samples were drawn for determination of gastrointestinal hormones. The duration of each experiment was 4 h; with 1 h fasting and 3 h continuous administration of nutrients.

RESULTS

During proximal jejunal feeding, pancreatic enzyme output increased significantly over basal levels. No significant increase over basal levels was observed during distal jejunal feeding. Bilirubin output and gallbladder contraction were significantly (P < 0.05) reduced during distal compared to proximal jejunal feeding. No significant differences were found in plasma levels of CCK, PYY and neurotensin between proximal and distal jejunal feeding.

CONCLUSION

Continuous feeding in the distal jejunum does not stimulate exocrine pancreatic secretion but maintains gallbladder contraction, although to a lesser extent. These effects are not related to hormonal changes but probably reduced activation of the enteropancreatic reflexes.

Faecal parameters in the assessment of activity in inflammatory bowel disease

BACKGROUND

Determination of inflammatory activity is helpful when assessing the efficacy of drugs in therapeutic trials and in facilitating management of individual patients with inflammatory bowel disease (IBD). Faecal parameters have been hypothesized to be more specific than non-faecal measurements in the assessment of intestinal inflammation.

METHODS

Review of the literature on faecal measurements in IBD.

RESULTS AND CONCLUSIONS

Leakage of various proteins and leukocyte products into the intestinal lumen can be assessed and quantified in stool specimens and serve as a measurement of inflammatory activity. Several of these faecal parameters are raised in patients with IBD. There is a considerable overlap between patients with active and those with inactive disease, however, and the correlation of the faecal parameters with disease activity indices is often low. The value of alpha1-antitrypsin measurement in faeces in the assessment of intestinal inflammation has been well established. Further studies in patients with IBD are needed to determine whether other faecal parameters, such as lactoferrin, tumour necrosis factor alpha, PMN-elastase, lysozyme, leucocyte esterase, immunoglobulin A, among others, are more accurate or cost-effective than measurement of alpha1-antitrypsin in the stools of such patients.

Cholecystokinin secretion in patients with chronic pancreatitis and after different types of pancreatic surgery

Cholecystokinin (CCK) secretion may be affected in patients with chronic pancreatitis (CP), but little is known on the effect of pancreatic surgery on CCK secretion. We measured CCK secretion (radioimmunoassay, RIA) in response to bombesin infusion (100 ng/kg/20 min) for 120 min to test CCK secretory capacity, to ingestion of a liquid diet (400 kcal) for 120 min, and in response to a solid fat-rich meal (500 kcal) for 120 min. These studies were performed in 45 patients with CP (25 with exocrine insufficiency), 15 patients after duodenum-preserving pancreatic head resection (DPRHP), 18 patients after the Whipple operation, 12 patients after distal pancreatectomy (DP), and 35 control subjects. In CP patients, the CCK secretory capacity was preserved, but the postprandial CCK response was reduced, depending on meal composition and the presence of exocrine insufficiency. In patients after Whipple's operation, CCK secretory capacity and postprandial CCK secretion were significantly (p < 0.05) reduced. In patients after DPRHP, CCK secretory capacity was not affected, but the postprandial CCK response was significantly (p < 0.05) reduced, depending on meal composition and the presence of exocrine insufficiency. In patients after DPRHP, fasting plasma CCK levels were significantly (p < 0.01) increased, pointing to the absence of feedback inhibition on CCK secretion by intraluminal enzymes. After DP, the CCK secretory capacity was not affected.

IN CONCLUSION

alterations in CCK secretion are observed in patients with chronic pancreatitis and after pancreatic surgery. These alterations are related not only to the disease process (exocrine insufficiency) but also to the type of surgery and type of stimulus.

Differences in cholecystokinin release and gallbladder contraction between emulsified and nonemulsified long-chain triglycerides

BACKGROUND

Fat is a potent stimulus of cholecystokinin (CCK) release. Apart from lipolysis, fatty acid chain length, and saturation, emulsification may also determine the magnitude of CCK release.

METHODS

We have studied the effect of emulsification of soybean oil on CCK and pancreatic polypeptide (PP) release (radioimmunoassay [RIA]) and gallbladder motility (ultrasonography). Six healthy subjects were studied on three separate occasions in random order during (1) intraduodenal administration of emulsified long-chain triglycerides (LCT) (6 mmol/h for 120 minutes); (2) equimolar amounts of nonemulsified LCT with addition of emulsifier; and (3) saline with emulsifier (control).

RESULTS

Intraduodenal administration of both nonemulsified LCT and emulsified LCT induced significant (p < .05) increases in plasma CCK and PP levels and reductions in gallbladder volume. However, compared with nonemulsified LCT, emulsified LCT resulted in a readier and significantly stronger CCK release (212+/-62 pmol/L per 120 minutes vs 36+/-7 pmol/L per 120 minutes; p < .05); PP release (2034+/-461 pmol/L per 120 minutes vs 671+/-106 pmol/L per 120 minutes; p < .05); and gallbladder contraction (77%+/-2% vs 41%+/-7%; p < .05). No significant alterations were observed in plasma CCK or PP levels and gallbladder volume during administration of saline with emulsifier.

CONCLUSIONS

Intraduodenal administration of a low-dose emulsified LCT more potently stimulates CCK and PP release and gallbladder contraction in comparison to equimolar amounts of nonemulsified LCT. These findings point to an important role for solubilization of LCT in determining the magnitude of CCK release from the intestine.

Antroduodenal motility and small bowel transit during continuous intraduodenal or intragastric administration of enteral nutrition

BACKGROUND

Gastrointestinal intolerance is observed more frequently during intraduodenal (ID) tube feeding than during intragastric (IG) feeding, possibly because it evokes a stronger gastrointestinal response and accelerates small bowel transit. We have investigated whether the accelerated small bowel transit during ID feeding results from alterations in antroduodenal motility pattern.

DESIGN

The effect of IG and ID infusion of a polymeric diet (Nutrison, 125 kcal h-1) on antroduodenal motility, small bowel transit time (SBTT) and gastrointestinal hormone release was studied in nine healthy subjects. These subjects were studied on three occasions for 6 h during fasting, continuous IG or ID feeding.

RESULTS

Phase III recurrence time was significantly prolonged during IG feeding compared with fasting (240 +/- 51 vs. 136 +/- 24 min; P < 0.05). None of the subjects had recurrence of phase III during ID feeding; the fed motor pattern remained present. Parameters of fed motility (mean amplitude and motility index) were not significantly different between IG and ID feeding, although the frequency of antral and duodenal contractions was lower during ID than during IG feeding. SBTT was significantly accelerated during ID compared with IG feeding and with fasting (58 +/- 8 vs. 73 +/- 9 and 83 +/- 10 min respectively; P < 0.05). Plasma cholecystokinin (CCK) and pancreatic polypeptide (PP) levels were significantly higher during ID than during IG feeding. Peptide YY (PYY) levels were significantly higher during ID than during fasting, but not during IG feeding

CONCLUSIONS

During intraduodenal feeding, a fed motility pattern is preserved, whereas during intragastric feeding transition from a fed to a fasting motor pattern is observed in over 50% of the subjects. These differences may be related to augmented hormone release during intraduodenal feeding.

Serum gastrin and chromogranin A during medium- and long-term acid suppressive therapy: a case-control study

BACKGROUND

Serum chromogranin A (CgA) is regarded as a reliable marker of neuroendocrine proliferation. We previously described increased serum CgA levels during short-term profound gastric acid inhibition.

AIM

To investigate serum gastrin and CgA levels in dyspeptic patients during continuous medium- (6 weeks to 1 year), or long-term (1-8 years) gastric acid suppressive therapy.

PATIENTS AND METHODS

114 consecutive dyspeptic patients referred for upper gastrointestinal endoscopy were enrolled in a cross-sectional, case-control study [62 patients on continuous antisecretory therapy, either with proton pump inhibitors (n = 47) or H2-receptor antagonists (H2RA) (n = 15) for gastro-oesophageal reflux disease with or without Barrett's oesophagus or functional dyspepsia, and 52 age- and sex-matched patients without medical acid inhibition and with normal endoscopic findings (control group)]. Omeprazole doses ranged from 20 mg to 80 mg daily and ranitidine from 150 mg to 450 mg daily. Fasting serum CgA and serum gastrin levels were measured by radioimmunoassay (reference values: serum CgA < 4.0 nmol/L; serum gastrin < 85 ng/L).

RESULTS

Fasting serum CgA levels positively correlated with serum gastrin in the entire study population (r = 0. 55, P = 0.0001). Median serum CgA values were higher in patients treated with a proton pump inhibitor than H2RA [2.8 (2.0-5.9) nmol/L vs. 2 (1.9-2.3) nmol/L, P < 0.002] and controls [2.8 (2.0-5.9) nmol/L vs. 1.8 (1.5-2.2) nmol/L, P < 0.0001) and did not differ between patients treated with H2RA or controls. Serum gastrin and CgA levels in patients on proton pump inhibitor therapy positively correlated with the degree and duration of acid inhibition. Patients on long-term proton pump inhibitor therapy had significantly higher fasting serum gastrin and CgA than those on medium-term proton pump inhibitor therapy [127 (73-217) ng/L vs. 49 (29-78) ng/L, P < 0.0001 and 4.8 (2.8-8) ng/L vs. 2.1 (1.9-2.6) ng/L, P < 0.001]. No such relation was found in patients on medium- vs. long-term H2RA. Overall, patients with positive Helicobacter pylori serology had higher serum gastrin and CgA levels than those with negative H. pylori serology [51 (27-119) ng/L vs. 27 (14-79) ng/L, P = 0.01, 2.4 (1.9-3.4) nmol/L vs. 2.0 (1.7-2.5) nmol/L, P = 0.05].

CONCLUSIONS

During long-term continuous proton pump inhibitor treatment, serum gastrin and CgA levels are significantly elevated compared to H2RA treatment and nontreated dyspeptic controls. H. pylori infection seems to affect gastric ECL cell secretory function. Increased serum CgA values during long-term profound gastric acid inhibition could reflect either gastric enterochromaffin-like cell hyperfunction or proliferative changes.

Effect of intragastric or intraduodenal administration of a polymeric diet on gallbladder motility, small-bowel transit time, and hormone release

OBJECTIVE

During postpyloric tube feeding, GI intolerance is observed more frequently than during prepyloric feeding, possibly by evoking a stronger GI response.

METHODS

We investigated the effect of intragastric and intraduodenal administration of a polymeric diet (125 kcal/h) on gallbladder motility (by ultrasonography), duodeno-cecal transit time (by lactulose H2 breath test), and GI hormone release (including cholecystokinin, pancreatic polypeptide, and gastrin). Six healthy subjects (two male, four female; mean age 22 yr, range 18-27 yr) were studied on two separate occasions in random order during 6 h of continuous administration of the diet through either the gastric or duodenal port of a two-lumen tube.

RESULTS

Intraduodenal feeding resulted in a more rapid contraction of the gallbladder, from 32 +/- 4 to 23 +/- 4 cm3 at 10 min (p < 0.05), reaching a minimum of 6 +/- 1 cm3, in contrast to intragastric feeding (31 +/- 4 to 19 +/- 3 cm3 at 60 min, p < 0.05; minimum 14 +/- 1 cm3). The gallbladder remained contracted during the 6-h study period during both intraduodenal and intragastric feeding. Small-bowel transit time was significantly accelerated during intraduodenal compared with intragastric feeding (51 +/- 12 vs 81 +/- 9 min; p = 0.003). Plasma cholecystokinin secretion was significantly (p < 0.05) increased during intraduodenal compared with intragastric feeding (848 +/- 107 vs 279 +/- 89 pmol x L(-1) x 360 min). The same was true for pancreatic polypeptide secretion. However, gastrin release was significantly (p < 0.05) higher during intragastric feeding.

CONCLUSIONS

Intraduodenal feeding elicited a stronger GI response than intragastric feeding, as demonstrated by accelerated small-bowel transit time, more rapid and stronger gallbladder contractions, and increased cholecystokinin and pancreatic polypeptide release. Gastrin release, on the other hand, was stronger during intragastric feeding.

Effects of somatostatin on proximal gastric motor function and visceral perception

BACKGROUND

Somatostatin affects gastrointestinal motility and secretion and visceral sensation, but little is known about its effects on the proximal stomach.

AIM

To evaluate the effects of somatostatin on proximal gastric motor function and perception of symptoms.

METHODS

Six healthy subjects participated in two experiments performed in random order during continuous intravenous infusion of saline or somatostatin (250 microg/h). Proximal gastric motor function was evaluated using a barostat. We performed pressure and volume distensions and a barostat procedure (minimal distending pressure + 2 mmHg). Symptoms were evaluated at regular intervals using visual analogue scales (VAS).

RESULTS

Neither minimal distending pressure nor gastric fundal tone were significantly different between somatostatin and saline. Pressure-volume curves during distensions were not influenced by somatostatin. However, phasic volume waves were significantly (P < 0.001) reduced by somatostatin, and somatostatin significantly (P < 0.05) reduced symptom perception of fullness and abdominal pressure during stepwise distensions.

Dose-dependent inhibition of postprandial gallbladder motility and plasma hormone secretion during acute hyperglycemia

BACKGROUND

Actual blood glucose concentrations influence gastrointestinal function. We investigated whether in healthy subjects the inhibitory effect of acute hyperglycemia on gallbladder motility is dose-dependent.

METHODS

Seven healthy volunteers were studied on four separate occasions in random order during euglycemia and during hyperglycemic clamping, at 4 mmol/l, 8 mmol/l, 12 mmol/l, and 16 mmol/l, respectively. Gallbladder volumes (ultrasonography) and plasma hormone release were studied before and after ingestion of a meal.

RESULTS

Postprandial gallbladder contraction was significantly (P < 0.05) and dose-dependently inhibited during the hyperglycemic experiments at 8, 12, and 16 mmol/l (56%+/-8%, 49%+/-8%, and 30%+/-5%, respectively) compared with euglycemia (68%+/-6%). Postprandial cholecystokinin release was significantly (P < 0.05) reduced compared with euglycemia only at a plasma glucose level of 16 mmol/l (116+/-28 versus 159+/-13 pmol x l(-1) x 120 min). Plasma pancreatic polypeptide secretion, as an indirect measure of vagal-cholinergic tone, was significantly (P < 0.05) and dose-dependently reduced during hyperglycemia at 8, 12, and 16 mmol/l.

CONCLUSION

In healthy subjects acute hyperglycemia significantly and dose-dependently inhibits postprandial gallbladder motility. Future studies on gallbladder motility should take into account the influence of plasma glucose, because already at postprandial glucose levels gallbladder motility is reduced.

Role of cobalamin intake and atrophic gastritis in mild cobalamin deficiency in older Dutch subjects

BACKGROUND

The reason for the high prevalence of mild cobalamin (vitamin B-12) deficiency in the elderly is poorly understood.

OBJECTIVE

We aimed to determine the reason for this high prevalence.

DESIGN

We examined cobalamin intake, the presence and severity of atrophic gastritis, the presence of Helicobacter pylori infection, and plasma cobalamin and methylmalonic acid (MMA) concentrations in 105 healthy, free-living, older subjects aged 74-80 y.

RESULTS

Mild cobalamin deficiency, ie, low to low-normal plasma cobalamin concentrations (< 260 pmol/L) and elevated plasma MMA concentrations (> 0.32 micromol/L), were found in 23.8% of subjects; 25.7% of subjects were not cobalamin deficient (plasma cobalamin > or = 260 pmol/L and plasma MMA < or = 0.32 micromol/L). Six subjects (5.8%), including 1 with mild cobalamin deficiency, had dietary cobalamin intakes below the Dutch recommended dietary intake of 2.5 microg/d. Mildly cobalamin-deficient subjects had lower total (diet plus supplements) cobalamin intakes (median: 4.9 microg/d; 25th and 75th percentiles: 3.9, 6.4) than did non-cobalamin-deficient subjects (median: 6.3 microg/d; 25th and 75th percentiles: 5.4, 7.9) (P = 0.0336), mainly because of less frequent use of cobalamin supplements (8% compared with 29.6%; chi2 = 3.9, P = 0.048). Atrophic gastritis was found in 32.4% of the total study group: mild to moderate in 19.6% and severe in 12.7%. The prevalence of severe atrophic gastritis, but not mild-to-moderate atrophic gastritis, was higher in mildly cobalamin-deficient subjects (25%) than in non-cobalamin-deficient subjects (3.7%) (chi2 = 4.6, P = 0.032). The prevalence of immunoglobulin G antibodies to H. pylori was similar in mildly cobalamin-deficient subjects (54.2%) and in non-cobalamin-deficient subjects (44.4%) (chi2 = 0.5, P = 0.5).

CONCLUSIONS

The high prevalence of mild cobalamin deficiency in healthy, free-living, older Dutch subjects could be explained by inadequate cobalamin intake or severe atrophic gastritis in only 28% of the study population. Other mechanisms explaining mild cobalamin deficiency in older people must be sought.

Expression of somatostatin receptors in human pancreatic tumor

Somatostatin (SST) and its analogues are candidates for use as endocrine agents in the treatment of pancreatic neoplasm. To determine whether the status of SST receptors in the human pancreatic tumors differs from that in the tumor-free pancreata of the human and whether pancreatic adenocarcinoma expresses the same subgroup of SST receptors as found in gastrinomas, this study visualized and characterized SST receptors in human control pancreata (n = 10) as well as pancreatic cancers (n = 12) and gastrinomas (n = 8) with storage phosphor autoradiography. Both pancreatic adenocarcinoma and gastrinoma expressed specific SST receptors. The binding capacity (Bmax, 35.4 +/- 7.6 fmol/mg protein) and the affinity (Kd, 0.32 +/- 0.27 nM) of SST receptors in gastrinomas were significantly higher than in pancreatic cancers (Bmax, 15 +/- 2.5 fmol/mg protein; Kd, 2.16 +/- 0.4 nM). No specific SST receptors were detected in the human control pancreata. Octreotide showed similarly high potencies of inhibition of 125I-SST-28 binding as SST-28 in gastrinomas. Unlike gastrinomas, little competitive binding of 125I-SST-28 was found with octreotide in pancreatic cancers. In conclusion, compared with the control pancreas, an up-regulation of SST receptors was present in both pancreatic cancer and gastrinoma. The subgroup of SST receptors in pancreatic cancers differs from that in gastrinomas.

Hypergastrinaemia during long-term omeprazole therapy: influences of vagal nerve function, gastric emptying and Helicobacter pylori infection

AIM

elucidate the mechanisms that lead to severe hypergastrinaemia during long-term omeprazole therapy for gastro-oesophageal reflux disease (GERD).

PATIENTS AND METHODS

A total of 26 GERD patients were studied during omeprazole maintenance therapy. Twelve patients with severe hypergastrinaemia (gastrin > 400 ng/L) were compared with 14 control patients (gastrin < 300 ng/L). Helicobacter pylori serology and a laboratory screen were obtained in all patients. Gastric emptying was scored by the evidence of food remnants upon endoscopy 12 h after a standardized meal. Gastric antrum and corpus biopsies were analysed for histological parameters, as well as somatostatin and gastrin concentrations. All patients underwent a meal-stimulated gastrin test and the hypergastrinaemia patients also underwent a vagal nerve integrity assessment by pancreatic polypeptide testing (PPT).

RESULTS

Severe hypergastrinaemia patients had a longer duration of treatment (80 vs. 55 months; P = 0.047) and were characterized by a higher prevalence of H. pylori infection (9/12 vs. 2/14, P = 0.004), corpus mucosal inflammation and atrophic gastritis (P < 0.04). This was reflected in lower serum pepsinogen A concentrations (mean +/- S.E.M. 53.6 +/- 17.9 vs. 137 +/- 16.0 mg/L, P = 0.03), pepsinogen A/C ratio (1.8 +/- 0.3 vs. 4.1 +/- 0.6, P = 0.005) and mucosal somatostatin concentrations (2.75 +/- 0.60 vs. 4.48 +/- 1.08 mg/g protein, P = 0.038). Two patients in the hypergastrinaemia group had signs of delayed gastric emptying, but none in the normogastrinaemia group did (P = N.S.). In addition, both groups had a normal meal-stimulated gastrin response.

CONCLUSION

Severe hypergastrinaemia during omeprazole maintenance therapy for GERD is associated with the duration of therapy and H. pylori infection, but not with abnormalities of gastric emptying or vagal nerve integrity.

Levels of circulating cellular fibronectin are increased in patients with rheumatoid vasculitis

OBJECTIVE

To investigate whether serum levels of circulating cellular fibronectin (cFN) are increased in patients with rheumatoid arthritis (RA) complicated by vasculitis.

METHODS

Levels of serum cFN were determined by an enzyme-linked immunosorbent assay (ELISA) in 26 RA patients with histologically proven vasculitis of recent onset (RV) and were compared to the levels in 47 RA patients with extraarticular manifestations of recent onset but no histological evidence of vasculitis (RA+), 43 patients with uncomplicated RA (RA-), 16 patients with systemic lupus erythematosus and active disease (SLE), 30 patients with active Crohn's disease (CD), 21 young healthy controls (yHC) and 17 elderly healthy controls (eHC). Plasma levels of cFN and von Willebrand factor antigen were also determined in the RA patients.

RESULTS

In RV patients, the median cFN level was significantly (P = 0.01) higher compared to that of RA+ patients, and was also significantly (P < 0.0000) higher compared to the cFN level in the RA-, SLE, CD, yHC and eHC groups. When compared to eHC, the cFN level was significantly higher in RA+ (P = 0.008); it was also higher in RA-, although not significantly (P = 0.42). 77% of the RV patients, 55% of the RA+ patients, and 37% of the RA-patients had a cFN level > 2 SD above the mean level for eHC. At an optimal cut-off titre the sensitivity of the cFN ELISA in discriminating RV patients from RA+ patients was 90%, the specificity was 46% and the accuracy was 68%. Plasma levels of cFN correlated significantly (r = 0.62; P < 0.001) with the von Willebrand factor antigen levels.

CONCLUSIONS

Increased levels of serum cFN are present in patients with RA, and are frequently found in RA patients with extraarticular manifestations, particularly in those with vasculitis.

Effect of medium- and long-chain triglycerides on lower esophageal sphincter pressure: role of CCK

Fat meals are known to decrease lower esophageal sphincter (LES) pressure, possibly through postprandial CCK release. Dietary fat consists mainly of long-chain triglycerides (LCT), which potently stimulate CCK secretion. This effect contrasts with that of medium-chain triglycerides (MCT), which do not induce CCK release. We recorded LES pressure and gallbladder volume in six healthy subjects on five separate occasions during intraduodenal administration of 1) saline control, 2) LCT, 3) MCT, 4) LCT during intravenous infusion of the CCK receptor antagonist loxiglumide, and 5) MCT together with loxiglumide. LES pressure decreased significantly during administration of both LCT and MCT. Loxiglumide completely prevented the reduction in LES pressure during intraduodenal LCT, but not during intraduodenal MCT. Gallbladder volume decreased during LCT, but not during MCT. It is concluded that intraduodenal administration of equimolar amounts of both LCT and MCT significantly reduces LES pressure. The effect of LCT on LES pressure is mediated by CCK. The effect of MCT is not dependent on CCK, since MCT does not release CCK and loxiglumide does not prevent the MCT-induced reduction in LES pressure.

Fecal lysozyme in assessment of disease activity in inflammatory bowel disease

This study was undertaken to determine whether measurement of fecal lysozyme is helpful in determining disease activity in inflammatory bowel disease. In 112 patients with Crohn's disease, 46 patients with ulcerative colitis, and 40 controls, fecal lysozyme concentration was measured. Results were correlated with CDAI and AI in Crohn's disease and with Truelove and Witts' grading in ulcerative colitis. Fecal lysozyme concentration (mean +/- SEM) was significantly (P < 0.001) higher in Crohn's disease (75 +/- 14 microg/g) and ulcerative colitis (238 +/- 33 microg/g) than in controls (6 +/- 1 microg/g). There was only a weak correlation between fecal lysozyme concentration and CDAI (r = 0.32; P = 0.001) and AI (r = 0.38; P < 0.0005) in patients with Crohn's disease and with Truelove and Witts' grading (r = 0.47; P = 0.001) in ulcerative colitis. When CDAI > or = 150 or AI > or = 100 were used as the standard for active disease, fecal lysozyme concentration was elevated in 78% of patients with active colonic Crohn's disease. In ulcerative colitis fecal lysozyme concentration was increased in active disease (95% in grade II and 94% in grade III) as compared 33% in grade I. Measurement of fecal lysozyme is of little help in diagnosing and determining disease activity of inflammatory bowel disease as whole, but it may be of help for diagnosis and assessment of activity of colonic IBD.

Interdigestive antroduodenal motility and gastric acid secretion

BACKGROUND

In humans, interdigestive acid secretion and antroduodenal motility are closely related with cyclic variations in acid secretion, synchronous with the various phases of the migrating motor complex (MMC). Duodenal acidification inhibits antral motility, but little is known about the effect of acute acid inhibition on antroduodenal motility.

AIM

To study the effect of acute acid inhibition on antroduodenal motility.

SUBJECTS

Ten healthy volunteers (four men and six women: age range 20-31 years).

METHODS

Antroduodenal motility (perfusion manometry) and gastric acid secretion (continuous aspiration with recovery marker) were measured simultaneously. Each subject was studied twice in random order during (1) intravenous infusion of saline for one-two complete MMC cycles and (2) during acute acid inhibition with intravenous famotidine (bolus 20 mg, continuous infusion 4 mg/h) for one-two complete MMC cycles or at least 240 min.

RESULTS

In the saline study, acid output in phase III (2.1 +/- 0.3 mmol/10 min) and late phase II (1.7 +/- 0.2 mmol/10 min) was significantly (P<0.05) increased over early phase II and phase I (1.2 +/- 0.2 and 1.2 +/- 0.2 mmol/10 min, respectively). Famotidine increased gastric pH to above pH 6 within 30 min. After acid inhibition, duration of MMC cycle during famotidine (106 +/- 8 min) was not significantly different from the saline experiment (133 +/- 14 min). Phase distribution of the MMC cycle was not significantly different between famotidine (I, II and III: 12 +/- 3, 82 +/- 3 and 5 +/- 1%) and saline (I, II and III: 13 +/- 3, 83 +/- 3 and 4 +/- 1%).

CONCLUSIONS

Gastric acid secretion varies cyclically with interdigestive antroduodenal motility. Acute acid inhibition with intravenous famotidine does not significantly affect interdigestive antroduodenal motility.

Gallbladder motility and cholecystokinin secretion during continuous enteral nutrition

OBJECTIVES

During total parenteral nutrition, gallbladder motility is impaired, resulting in sludge and stone formation. Little is known about gallbladder motility during prolonged enteral nutrition.

METHODS

We studied gallbladder motility during continuous enteral nutrition (CEN) in nine hospitalized patients with active inflammatory bowel disease. The patients received a polymeric diet (2000 kcal/24 h) by CEN through a nasogastric tube for a prolonged period. Gallbladder volumes were obtained daily by ultrasonography, starting from day 0 (before CEN) and on 7 consecutive days during CEN. At days 0, 1, 4, and 7, the gallbladder response to i.v. cholecystokinin (CCK-33; 0.5 Ivy Dog unit/kg/h) was studied. Plasma CCK levels were determined at regular intervals by radioimmunoassay.

RESULTS

No significant differences were observed on day 0 between patients and a group of nine healthy control subjects in fasting gallbladder volumes (19.4 +/- 2.3 and 19.6 +/- 2.4 cm3, respectively) and gallbladder contraction during CCK infusion (56 +/- 14% and 69 +/- 7%, respectively). During CEN, from day 1 to day 7, mean gallbladder volume remained significantly (p < 0.05) reduced compared with fasting gallbladder volume, and mean plasma CCK levels remained significantly (p < 0.05) increased compared with fasting levels. Although gallbladder volume was significantly reduced during CEN, the gallbladder contractile response to CCK was not affected; at days 1, 4, and 7, gallbladder contraction was 36-57%.

CONCLUSIONS

During CEN, 1) gallbladder volume is significantly reduced and plasma CCK levels are significantly increased, 2) these effects are sustained over time (7 days), and 3) the gallbladder remains responsive to exogenous CCK. These results indicate that gallbladder contractility and gallbladder responsiveness to CCK are preserved during prolonged CEN in patients with inflammatory bowel disease.

Low seroprevalence of Helicobacter pylori antibodies in historical sera of patients with Crohn's disease

BACKGROUND

Our aim was to determine the seroprevalence of Helicobacter pylori antibodies in historical sera from a large group of patients with Crohn's disease and to compare the findings with those of a control group of healthy blood transfusion donors.

METHODS

The historical sera from 386 patients with Crohn's disease were studied (serum age, 9.9 years; range, 0.4-21.6 years). Serum IgG and IgA H. pylori antibodies were measured with enzyme-linked immunosorbent assay. Western blots (detecting IgG only) were also used to study a subpopulation of the patients' sera and to assess the presence of cagA bands, indicating a cytotoxic variety of H. pylori. The serology of the Crohn's disease patients was compared with that of 277 age-matched controls. A longitudinal follow-up study of 14 IgG and IgA anti-H. pylori-positive and 14 IgG- and IgA-negative Crohn's disease patients was also performed (mean follow-up, 7.6 years; range, 1.7-20.5 years).

RESULTS

Of the total Crohn's disease patients, 47 (12.2%) had IgG antibodies against H. pylori, 67 (17.4%) had IgA antibodies, and 31 (8.0%) had both IgG and IgA antibodies. The corresponding antibody positivities for the controls were 98 (35.4%) for IgG, 77 (27.8%) for IgA, and 64 (23.1%) for both IgG and IgA. When compared, with the control group, the seroprevalence of H. pylori in the Crohn's disease patients was significantly lower (P < or = 0.002). In addition the relative IgG response of the patients was lower than the IgA response. The opposite was true for the controls. There was no difference in the absolute levels of H. pylori antibodies between patients and controls. In the follow-up study two patients initially IgG-positive for H. pylori became negative over time; these patients had been treated for their infection. the rest, who continued to be positive, were not treated. One patient who was initially IgA-positive also became IgA-negative over time. The follow-up group, who were initially IgG- and IgA-negative, remained IgG-negative with time, and two patients became IgA-positive. Findings of anti-H. pylori IgG were confirmed with Western blots. Furthermore, these showed that of the H. pylori-positive patients (indicated by their IgG positivity), 66% were infected with a cytotoxic (cagA-positive) variety, compared to 69.4% of the controls.

CONCLUSIONS

Patients with Crohn's disease have a lower prevalence of H. pylori antibodies than an age-matched control group. There is a reversal of the relative IgG and IgA responses in Crohn's disease patients compared with the controls. Of the Crohn's disease patients with H. pylori most are infected with cytotoxic varieties, similar to controls.

Treatment of Helicobacter pylori infection favourably affects gastric mucosal superoxide dismutases

BACKGROUND AND AIMS

Excessive production of reactive oxygen metabolites (ROMs) by phagocytic cells is thought to contribute to the mucosal pathology of Helicobacter pylori infection. Previously, H pylori infection was shown to have a differential effect on some gastric mucosal scavenger enzymes of ROMs-namely, mitochondrial and cytoplasmic superoxide dismutases-reflected by a large increase in the cytokine inducible manganese superoxide dismutase and a marginal decrease in the constitutive copper/zinc superoxide dismutase. The present study was performed to evaluate whether these altered mucosal superoxide dismutase concentrations and activities in H pylori associated gastritis are reversed to normal by successful treatment of the infection.

PATIENTS AND METHODS

In two different treatment groups-namely, omeprazole or ranitidine, in combination with clarithromycin and metronidazole (OME/AB (n = 33) and RAN/AB (n = 30))-manganese superoxide dismutase and copper/zinc superoxide dismutase concentrations were evaluated by enzyme linked immunosorbent assays in homogenates of gastric antrum and corpus biopsy specimens obtained before and eight weeks after successful treatment of H pylori infection. Superoxide dismutase activities in these homogenates were determined spectrophotometrically in eight patients of both groups before and after successful treatment. The concentrations of gastric mucosal superoxide dismutases were also determined in 12 patients with a persistent H pylori infection, with (n = 4) or without (n = 8) eradication therapy. Infection and eradication of H pylori were confirmed by a combination of culture and histology.

RESULTS

Concentrations of manganese superoxide dismutase were significantly lower after than before therapy in antral (p < 0.001 in both treatment groups) and corpus (p < 0.001 in both treatment groups) mucosa. By contrast, copper/zinc superoxide dismutase concentrations were significantly higher (p < 0.001) only in antral mucosa of the OME/AB treated group. Manganese superoxide dismutase activity was significantly lower after than before treatment in antral (OME/AB p < 0.01, RAN/AB p < 0.001), but not in corpus mucosa. Copper/zinc superoxide dismutase activity was not significantly altered by therapy. In the 12 patients with a persistent H pylori infection no major changes in the gastric mucosal superoxide dismutase concentrations were found.

CONCLUSIONS

The raised manganese superoxide dismutase and reduced copper/ zinc superoxide dismutase concentrations and activities in H pylori associated gastritis were reversed towards normal by successful treatment of the infection.

Doppler sonography evaluation of superior mesenteric artery flow to assess Crohn's disease activity: correlation with clinical evaluation, Crohn's disease activity index, and alpha 1-antitrypsin clearance in feces

OBJECTIVE

This study was undertaken to investigate the value of Doppler flow measurements of the superior mesenteric artery (SMA) as a marker for disease activity in patients with Crohn's disease.

SUBJECTS AND METHODS

Duplex Doppler sonography measurements of SMA blood flow volume were obtained in 29 consecutive patients with suspected Crohn's disease. We prospectively sought a correlation between the independent assessment of Doppler flow measurements and markers for disease activity: Crohn's disease activity index and fecal alpha 1-antitrypsin clearance and our reference standard based on clinical history, physical examination, laboratory values, endoscopy, surgery, and follow-up.

RESULTS

In 27 of 29 patients, adequate measurements of SMA blood flow were obtained. In 15 patients no disease activity was judged to be present or no Crohn's disease (n = 2) was found at follow-up (group 1). In 12 patients, activity of Crohn's disease was diagnosed (group 2) on the basis of the reference standard. In group 2 the Doppler SMA blood flow values were significantly higher (p < .05) than those for group 1 (826 +/- 407 ml/min versus 323 +/- 103 ml/min). Of the other parameters investigated, only the alpha 1-antitrypsin value correlated with the reference standard but to a lesser degree than the values for SMA blood flow measurement.

CONCLUSION

This prospective study shows that SMA Doppler blood flow measurements can be used to assess disease activity in patients with Crohn's disease. This approach may be of value in the diagnosis and follow-up of patients with Crohn's disease, providing directly available, quantifiable, noninvasive information on disease activity.

Expression of peptide receptors in human endocrine tumours of the pancreas

BACKGROUND

Gut peptides are known to influence hormone release and growth of endocrine tumours of the pancreas. Although information on somatostatin receptors has been provided recently, little is known on the receptor status of other gastrointestinal hormones in such tumours.

AIMS

To analyse the spectrum of gut hormone receptors on endocrine tumours of pancreas.

SUBJECTS

Four types of endocrine tumours from eight patientS.

METHODS

The receptors for bombesin, secretin, vasoactive intestinal peptide, cholecystokinin, and somatostatin have been visualised and quantified with storage phosphor autoradiography.

RESULTS

Bombesin receptors were present in all five gastrinomas and two primary VIPomas. Secretin receptors were expressed in four primary gastrinomas and one primary VIPoma from pancreas. Vasoactive intestinal peptide receptors were identified in four primary gastrinomas and all VIPomas. Furthermore, all VIPomas expressed cholecystokinin-B (gastrin) receptors, whereas, gastrinomas did not contain cholecystokinin-B receptors. The receptors for somatostatin were detected in all gastrinomas and VIPomas. Both somatostatinoma and glucagonoma were negative for all five types of peptide receptors studied.

CONCLUSIONS

Besides somatostatin receptors, most of gastrinomas and VIPomas also express receptors for bombesin, secretin, and vasoactive intestinal peptide.

Expression of receptors for gut peptides in human pancreatic adenocarcinoma and tumour-free pancreas

Gut hormones that modulate the growth of normal pancreas may also modulate the growth of cancers originating from pancreas. This study visualized and compared the receptors for cholecystokinin (CCK), bombesin (BBS), secretin and vasoactive intestinal peptide (VIP) in tumour-free tissue sections of human pancreas (n = 10) and pancreatic ductal adenocarcinomas (n = 12) with storage phosphor autoradiography using radioligands. CCK-B receptors, present in control pancreata, were not detected in any of the pancreatic cancers. BBS receptors were visualized in control pancreata, but they were absent in 10 of 12 pancreatic cancers. In 5 of 12 pancreatic cancers, receptors for secretin were visualized, while binding for secretin was present in all tumour-free pancreata. Conversely, no specific binding of VIP was detected in control pancreata but was identified in 3 of 12 pancreatic cancer specimens. It is concluded that the expression of gut peptide receptors in pancreatic cancer differs from that in tumour-free pancreas. Receptors for these peptides are present in only a minority of pancreatic cancer specimens.

Cholecystokinin receptors in human pancreas and gallbladder muscle: a comparative study

BACKGROUND & AIMS

Cholecystokinin (CCK) receptors mediate pancreatic secretion and gallbladder contraction. Hitherto, little information on characteristics of CCK receptors in the human pancreas was available. This study identifies CCK receptors in the human pancreas and compares their characteristics with the CCK receptors in the human gallbladder.

METHODS

Visualization and quantification of 125I-Bolton-Hunter sulfated CCK octapeptide (125I-BH-CCK-8) binding to tissue sections of the human pancreas and gallbladder were performed by storage phosphor autoradiography.

RESULTS

Specific bindings for CCK were visualized in pancreatic tissue and the smooth muscle layer of the gallbladder. Binding of 125I-BH-CCK-8 to the pancreas was inhibited by agonists with the affinities (dissociation constant) of CCK (0.11 nmol/L) approximately gastrin (0.15 nmol/L) and by antagonists with the affinities of CCK-B receptor antagonist (L365,260, 0.18 nmol/L) > CCK-A receptor antagonist (lorglumide, 8.1 nmol/L). In contrast to the pancreas, binding of 125I-BH-CCK-8 to the gallbladder muscle was inhibited with high affinity by CCK-8 and lorglumide but was replaced to a small degree by gastrin and L365,260.

CONCLUSIONS

The sub-types of receptors for CCK in the human pancreas and gallbladder are different. The human pancreas predominantly expresses CCK-B receptors, whereas only CCK-A receptors were localized in the human gallbladder muscle.

Expression of receptors for gut peptides in pancreata of BOP-treated and control hamsters

The growth of pancreatic cancers may be influenced by certain gut peptides. However, the alteration of gut peptide receptors in the progress of pancreatic carcinogenesis is largely unknown. With storage phosphor autoradiography, this study visualized and characterized receptors for cholecystokinin (CCK), somatostatin (SST), bombesin (BBS), secretin and vasoactive intestinal peptide (VIP) in pancreata of control hamsters (n = 7) and pancreatic preneoplastic lesions (n = 10) or adenocarcinomas (n = 10) of N-nitrosobis(2-oxopropyl)amine (BOP)-treated hamsters. The specific CCK-A and secretin receptors expressed in normal pancreata were markedly reduced in pancreatic preneoplastic lesions and absent in adenocarcinomas. In the development of pancreatic tumours, the subgroup of SST receptors did not change, but both the affinity and binding capacity declined. In comparison with the binding of VIP to normal pancreata, specific VIP binding was significantly lower in preneoplastic lesions and almost absent in pancreatic adenocarcinomas. No specific binding for BBS was detected in normal pancreas or (pre)neoplastic lesions of hamster pancreas. The reduction or absence of receptors for CCK, secretin, SST and VIP in hamster pancreas with the progress of carcinogenesis suggests that in BOP-treated hamsters, pancreatic adenocarcinomas have, to a large extent, lost the hormone-dependent characteristics of the original tissue.

Visualization and characterization of CCK receptors in exocrine pancreas of rat with storage phosphor autoradiography

Studies on cholecystokinin (CCK) receptors in rat pancreas are usually performed on homogenates. Using storage phosphor autoradiography, a new imaging technique with a high sensitivity and large linear dynamic range, we visualized and characterized CCK receptors in tissue sections of normal rat pancreas. The density of CCK receptors in pancreatic tissue sections from 10 normal rats appeared to be unevenly distributed and variable in serial sections. The binding of labeled CCK-8 was markedly inhibited by CCK-8 and CCK-A receptor antagonists, but it was only weakly affected by gastrin and CCK-B receptor antagonists. At room temperature the CCK-8 dose-inhibition curve was fitted by a two-site model: one with a high-affinity but low-capacity site and another with a low-affinity but high-capacity site. The CCK-8 dose-inhibition curve showed that the inhibition of the variable high-density receptors took place at a low concentration of CCK-8, while the diffuse low-density receptors were inhibited at the high concentration of 1 microM CCK-8. Binding of labeled CCK-8 at 37 degrees C was homogeneous with a low affinity and comprised only 4% of that found at room temperature. In summary, an uneven density of CCK receptors in the rat exocrine pancreas was observed and attributed to the variable expression of high-affinity CCK receptors in pancreatic acini.

Risk factors of peptic ulcer disease: different impact of Helicobacter pylori in Dutch and Japanese populations?

Helicobacter pylori, non-steroidal anti-inflammatory drugs, family history, blood group O, hyperpepsinogenaemia A, alcohol and smoking have been reported to be risk factors for peptic ulcer disease. The strength of causal risk factors may differ in different populations. In 215 Japanese and 493 Dutch employees of similar age, gender and type of occupation, a structured history was obtained using a questionnaire and fasting serum samples were analysed for IgG antibodies to H. pylori and pepsinogen A all in the same laboratory. A past ulcer history was verified through case notes. We found that H. pylori seropositivity, a high serum pepsinogen A and a family history of ulcer disease were significant and independent risk factors for peptic ulcer disease. For H. pylori seropositivity there was a 20-fold increased risk among the Dutch and an eight-fold increased risk among the Japanese. The seroprevalence of H. pylori was 90% in 20 Dutch subjects with a verified ulcer history and 95% in 41 Japanese ulcer subjects; it was 29% in Dutch non-ulcer subjects and 70% in Japanese non-ulcer subjects. The cumulative difference in risk to develop peptic ulcer disease at the age of 48 years between H. pylori-infected and -uninfected subjects was 24.5-3.0 = 21.5% for the Japanese and 11.8-0.5 = 11.3% for the Dutch. Duodenal ulcer disease was associated with a high coffee consumption only among the Japanese population, where this habit was much less prevalent than among the Dutch. In conclusion, the characterization of peptic ulcer risk factors as weak or strong has no universal basis: the present study shows that from a diagnostic point of view H. pylori appears to be a weaker risk factor for peptic ulcer disease in a society with a higher seroprevalence. However, from an aetiological point of view, H. pylori has an even greater impact on ulcer morbidity in the Japanese than in the Dutch population.