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Streptozotocin has been used to induce diabetes mellitus in experimental animals and has been thought to have a selective cytotoxic effect on the beta-cells in the islets of Langerhans. The aim of the present study was to determine whether streptozotocin has any cytotoxic effect on other neuroendocrine cells of the gastrointestinal tract. Eight female Sprague-Dawley rats received intraperitoneal injections of 100 mg/kg streptozotocin in citric acid buffer; the concentration of streptozotocin was adjusted to 25 mg/ml buffer. Seven rats, serving as controls, received an equivalent volume of the vehicle. The rats were killed after three days and the fundus, antrum, small intestine and pancreas were examined for neuroendocrine cells. Our study confirms that streptozotocin is cytotoxic towards beta-cells. In addition, it is cytotoxic towards neuroendocrine cells of the oxyntic mucosa of the stomach. This finding may have clinical significance and suggests that streptozotocin may be used in the treatment of gastric neuroendocrine tumors as well as insulinomas.

Gastrin-producing G cells constitute one of the major populations of neuroendocrine cells in the antral mucosa of the stomach. The peroxisome proliferator-activated receptor (PPAR) alpha-agonist ciprofibrate is used as a lipid-lowering drug. Recently, ciprofibrate has been shown to induce hypergastrinemia in rats without reducing gastric acidity, which indicates a direct stimulatory effect on the G cell. Gastrin probably plays an important role in gastric tumorgenesis, and long-term dosing with ciprofibrate results in enterochromaffin-like (ECL) cell carcinoids in the oxyntic mucosa of rats. In this study, we aimed to examine changes of neuroendocrine granules in G cells following ciprofibrate dosing and relate them to changes induced by the proton pump inhibitor pantoprazole. Furthermore, we wanted to study peroxisomes in G cells. Rats received ciprofibrate 80 mg/kg/day or pantoprazole 200 mg/kg/day in 4 weeks. Antral mucosal specimens were processed for conventional staining procedures and immunocytochemistry for both the light and electron micro-scope. Specimens were immunolabeled for gastrin and peroxisome-specific proteins. Electron micrographs were analyzed planimetrically. This study shows that hypergastrinemia induced by ciprofibrate is accompanied by a decrease in granule number per cell and a relative increase in electron-dense granules. These changes were quite similar to those induced by pantoprazole, indicating signs of G-cell activation in general. However, distinctions concerning granule size and composition and both hypertrophy and hyperplasia of G cells are presented. Finally, demonstration of peroxisomes in G cells was only achieved by using the highly sensitive tyramide signal amplification technique in immunostaining for the peroxisome-specific protein PMP-70. Therefore, neither morphological nor quantitative changes of peroxisomes in G cells were detected.

The role of the gastric acid secretagogues acetylcholine, gastrin and histamine has been debated for decades. Initially, the mast cell was considered the source of acid stimulatory histamine. Later, Håkanson & Owman (1969) showed that the entero-chromaffinlike (ECL) cell produces and stores histamine in several species, including rat and man. Kahlson et al. (1964) showed that food and gastrin stimulated oxyntic mucosal histamine synthesis and release, Berglindh et at. (1976) that histamine and cholinergics but not gastrin induced acid secretion in isolated oxyntic glands and parietal cells, and Rangachari (1995) that acetylcholine or gastrin released histamine in isolated mucosa. These findings suggested that gastrin stimulates acid secretion through release of ECL cell histamine. Studying simultaneous histamine release and acid secretion in isolated oxyntic mucosal cells, we found that gastrin stimulated acid secretion only in preparations releasing histamine. Moreover, in the isolated rat stomach, gastrin stimulated both histamine release and acid secretion. Maximal acid output was higher with histamine than with gastrin, and augmented by acetylcholine but not by gastrin. These findings strongly suggested that gastrin acts by releasing histamine. Finally, a fluorescein-labelled gastrin analogue bound to the ECL cell, not to the parietal or stem cell regions. This is interesting, recalling that gastrin has a potent and specific trophic effect on the ECL cell and only a general effect on all other oxyntic cell types. In conclusion, physiological observations are best explained by localising the CCK2 receptor only to the ECL cell, the other effects of gastrin on the gastric mucosa being secondary to the release of mediators from the ECL cell.

The peroxisome proliferator (PP) ciprofibrate stimulates gastrin-producing cells (G-cells) in the rat stomach by an unknown mechanism, inducing hypergastrinemia and secondary enterochromaffin-like (ECL) cell hyperplasia. Ciprofibrate is a specific ligand for the nuclear peroxisome proliferator-activated receptor alpha (PPAR alpha). To see whether the effects of ciprofibrate could be imitated, rats were given another PPAR alpha ligand WY-14643 or the PPAR gamma ligand troglitazone by gastric intubations daily for 28 and 56 days. Troglitazone failed to raise gastrin levels. WY-14643 increased gastrin mRNA abundance, G-cell density and induced hypergastrinemia, but to a lesser extent than ciprofibrate. ECL cell parameters increased in proportion with the relative hypergastrinemia. Ciprofibrate and WY-14643 altered the levels of acyl CoA-oxidase mRNA and PPAR alpha mRNA in antrum, but had no effect in corpus. The PPAR alpha receptor was found in at least some G-cells by immunostaining. This study supports the hypothesis that PPAR alpha specific ligands could stimulate the G-cells by acting locally from the stomach lumen through antral PPAR alpha.

Gastrin plays a crucial role in maintaining a normal cellular composition and function of the oxyntic mucosa. It has been debated for decades whether parietal cells possess cholecystokinin-2 (CCK(2)) receptors and interact directly with gastrin. We investigated whether parietal cells express CCK(2) receptor mRNA by using new molecular biology techniques. Rat oxyntic mucosal cells were dispersed and enriched by elutriation, and single parietal and ECL cells were isolated from cell smears by means of laser microbeam microdissection and laser pressure catapulting. The mRNA from each single cell was isolated and subjected to one-step multiplex or conventional reverse transcription-polymerase chain reaction and subsequent nested PCR. Specific primers for the CCK(2) receptor were used in combination with primers for H,K-ATPase and histidine decarboxylase, specific markers for parietal and ECL cells, respectively. CCK(2) receptor mRNA was detected in 25% of the rat parietal cells and 40% of the ECL cells examined.

The aim of the study was to determine if, by means of tyramide signal amplification (TSA), the presence of chromogranin A (CgA)-positive tumour cells could be demonstrated in breast cancer cases found to be negative by conventional immunohistochemical staining. Sections from 44 cases of breast cancer (28 infiltrating ductal carcinomas, 2 lobular carcinomas, 4 ductal carcinomas in situ (DCIS), 7 lobular carcinomas in situ (LCIS), and 3 mucinous carcinomas) were stained for CgA by conventional immunohistochemical methods and by immunohistochemistry with TSA. The sections were also histologically graded and their oestrogen receptor (ER), progesterone receptor (PgR) and HER-2 oncogene status was recorded. Five of the tumours showed CgA-positive staining with the polyclonal antibody 430 with conventional methods. Thirty cases showed CgA-immunoreactive tumour cells after immunohistochemical staining with the polyclonal antibody 430 with TSA. However, eight of these also showed faint staining with the negative control antibody X0936 with TSA. One case showed immunopositivity for CgA using a monoclonal antibody without tyramide amplification and only a further two cases were positive when TSA was applied. The presence of CgA appears to be associated with a lower histological grade and may be more often found in oestrogen receptor-positive tumours.

Background: Anaesthetic agents affect gastric acid secretion, but the mechanisms behind this action have not been fully evaluated. The enterochromaffin-like (ECL) cell plays a key role in the regulation of gastric acid secretion, and anaesthetic agents have recently been described as inhibiting histamine release from the ECL cell. The present study examines the effect of anaesthetic agents on the ECL cell and on parietal cell functions., Methods: Different concentrations of urethane, pentobarbital and a mixture of fluanisone/fantanyl/midazolam (FFM) were examined for the effect on gastrin-stimulated histamine release and acid secretion and on histamine-stimulated acid secretion in the totally isolated vascularly perfused rat stomach. The luminal acid output and histamine concentrations in venous effluents were measured by titration and radioimmunoassay, respectively., Results: Pentobarbital caused an inhibition on both histamine release and acid output in gastrin-stimulated stomachs in a concentration-dependent way. The mixture of FFM at higher concentrations inhibited histamine release from the ECL cell and luminal H+ output in gastrin-stimulated acid secretion. Urethane exerted a slight inhibitory effect on histamine release only at the lowest concentration. Pentobarbital also reduced histamine-stimulated gastric acid secretion, while the mixture of FFM did not., Conclusions: pentobarbital inhibits acid secretion both by reducing ECL cell histamine release and parietal cell H+ secretion, whereas FFM inhibits acid secretion by interaction with the ECL cell only. Urethane also had a slight inhibitory effect on the ECL cell histamine release at the lowest concentration.

After Helicobacter pylori eradication was introduced and largely eliminated the need for maintenance therapy for peptic ulcer disease, gastroesophageal reflux disease (GERD) became the main indication for prolonged gastric acid inhibition. The drug effect on GERD depends on the degree of acid inhibition, thus the efficacious proton pump inhibitors are preferred. The proton pump inhibitors have few immediate side effects, the main concern being the profound hypoacidity and hypergastrinaemia they induce. In short-term, hypergastrinaemia causes rebound hyperacidity, possibly worsening GERD and reducing the efficacy of histamine H(2) blockers. In the long-term, hypergastrinaemia causes enterochromaffin-like cell hyperplasia and carcinoids. Since enterochromaffin-like cells may be important in gastric carcinogenesis, iatrogenic hypergastrinaemia may predispose to carcinoma. Gastric hypoacidity also increases gut bacterial infections, and the barrier function of acid against viral and prion infections requires further assessment.

Background: The transmissible degenerative encephalopathies (TDEs) constitute a distinct group of diseases (scrapie in sheep, bovine spongiform encephalopathy (BSE) and Creutzfeldt-Jakob disease (CJD) in humans). The causal agents are not fully characterized, but are known to be resistant to most inactivation procedures. Ruminants appear to be particularly susceptible to TDEs. The concentrations of hydrochloric acid in their digestive tracts are significantly lower than in monogastric species., Methods: The aim of the study was to examine the role of gastric acidity in the protection of mice against infection after intragastric administration of different doses of a scrapie agent. Gastric acidity levels in mice were reduced by adding ranitidine to the drinking water and the animals were observed for neurological symptoms and at sacrifice examined microscopically for spongiform lesions in the brain., Results: The lower doses of infectious material induced disease significantly more often in mice given ranitidine compared with the controls., Conclusion: These data indicate that the normal levels of gastric acidity in mice protect them to some extent from infection with low doses of scrapie agent. This finding is potentially relevant to the pathogenesis of the variant form of CJD, which appears to be associated with the consumption of BSE-infected food products.

Patients with hypergastrinemia secondary to achlorhydria have an increased risk of developing ECL cell carcinoids and gastric adenocarcinomas. Hypergastrinemia is central in the pathogenesis of ECL cell carcinoids, but the link between gastrin and gastric carcinomas is controversial. During neoplastic transformation ECL cells may, however, lose many of their neuroendocrine characteristics, making them difficult to recognise as neuroendocrine with conventional immunohistochemical techniques. Neuroendocrine differentiation was therefore examined in eight gastric adenocarcinomas found in seven patients with severe hypergastrinemia and/or pernicious anemia using a monoclonal antibody towards chromogranin A and immunohistochemistry without and with a sensitive signal amplification technique. The Sevier-Munger method was used as a more specific marker of ECL cells. Seven of the carcinomas contained scattered neuroendocrine tumour cells. When using signal amplification, an increase in the number of immunoreactive neoplastic cells was seen. In many tumours, clusters or confluent sheets of such cells were disclosed, suggesting a neuroendocrine and ECL cell origin. These tumours may therefore be ECL cell carcinomas and hypergastrinemia may thus be involved in the tumourigenesis.

The effects of gastrin precursors have been discussed during recent years. However, the mechanism for their action, whether through a novel receptor on the parietal cell or a cholecystokinin-2 (CCK-2) receptor on the enterochromaffin like (ECL) cells, is still not settled. This study examines the effect of glycine-extended gastrin-17 (Gly-G-17), the main non-amidated gastrin precursor, on gastric acid secretion and histamine release in the totally isolated vascularly perfused rat stomach. Glycine-extended gastrin-17 at the concentrations from 0.52 to 520 nmol L(-1) was administered to the totally isolated vascularly perfused rat stomach. Glycine-extended gastrin-17 at 52 or 520 nmol L(-1), and gastrin-17 at 0.52 nmol L(-1)were co-administered to examine whether glycine-extended gastrin augmented maximal gastrin stimulated acid secretion and histamine release. Both Gly-G-17 at 52 nmol L(-1) and gastrin-17 (G-17) at 0.52 nmol L(-1) were administered together with the histamine-2 receptor antagonist ranitidine at 10 micromol L(-1). Gastric acid and venous histamine output were measured. Glycine-extended gastrin-17 at lower concentrations from 0.52 to 5.2 nmol L(-1) did not stimulate gastric acid output or histamine release, whereas higher concentrations from 52 to 520 nmol L(-1) elicited a concentration-dependent increase in acid secretion and histamine release. The outputs of acid and histamine at 520 nmol L(-1) Gly-G-17 were at the same level as those found for G-17 at its maximally effective concentration of 0.52 nmol L(-1). Glycine-extended gastrin-17 at maximally effective concentration of 520 nmol L(-1) did not augment maximal gastrin stimulated acid secretion or histamine release. Ranitidine inhibited G-17 and Gly-G-17 stimulated acid secretion to a similar degree. This study confirms that the stimulatory effect of Gly-G-17 on gastric acid secretion is via a CCK-2 receptor on the ECL cell.

The aims of the present study were to determine the effects of endothelin ET(A) receptor antagonism on carbon monoxide (CO)-induced cardiac hypertrophy and endothelin-1 (ET-1) expression and to compare myocardial effects of chronic nicotine with CO exposure. Female Sprague-Dawley rats (n = 84) were randomized to three groups exposed 20 h/day to CO (200 ppm), nicotine (500 microg/m3), or air for 14 consecutive days. In each exposure group, animals were randomized to ET(A) receptor antagonist LU 135252 in drinking water (0.5 mg/ml) or placebo. Myocardial ET-1 and atrial natriuretic peptide (ANP) expression was measured by competitive RT-PCR and plasma ET-1 by immunoassay. Carboxyhemoglobin was 22.1 +/- 0.3% in CO-exposed animals and 2.8 +/- 0.3% in controls. Plasma nicotine was 57 +/- 7 ng/ml and plasma cotinine was 590 +/- 23 ng/ml in nicotine-exposed animals and below detection levels in controls. CO exposure induced a 21% increase in right ventricular hypertrophy (p < 0.01), a 7% increase in left ventricular hypertrophy (p < 0.01), a 25% increase in right ventricular ET-1 expression (p < 0.05), and an eightfold increase in ANP expression (p = 0.08). ET(A) receptor antagonism reduced right ventricular hypertrophy by 60% (p < 0.05) with no significant effect on left ventricular hypertrophy or myocardial ET-1 expression. Chronic nicotine exposure did not significantly affect cardiac weights or ANP and ET-1 expression. We conclude that ET(A) receptor antagonism reduces right ventricular hypertrophy induced by chronic CO exposure, whereas CO-induced myocardial ET-1 expression remains unchanged., (Copyright 2002 Elsevier Science.)

Background/aims: Superficial mucosal damage is associated with mucosal hyperemia and release of histamine into venous blood and gastric lumen. This study was designed to examine if histamine administrated directly to gastric mucosa becomes absorbed and transported away with blood, and if so whether it is capable of increasing gastric mucosal blood flow., Methodology: Superficial mucosal injury was induced by exposing chambered rat stomachs to 2 M NaCl for 10 min, and 45 min later 4.5 x 10(-2) or 4.5 x 10(-3) M histamine was instilled into the chamber. Mucosal blood flow was determined by radioactive microspheres and continuously by Laser Doppler flowmetry., Results: Histamine concentration in arterial blood was markedly increased 15 min after administration of histamine. The mucosal blood flow did not increase after application of histamine. Significant increase in heart rate and fall in arterial blood pressure were observed. Similar results were obtained after application of histamine to normal mucosa., Conclusions: Histamine applied to injured or normal gastric mucosa of rats becomes transported via capillaries and venules to the systemic circulation, but does not reach terminal arterioles in quantities large enough to cause vasodilatation.

Background: The interrelationship between histamine and gastrin in the physiological regulation of gastric acid secretion is still a matter of dispute. CCK-2 receptors are located on enterochromaffin-like (ECL) cells in corpus mucosa and gastrin stimulates acid production by releasing histamine from the ECL cells, which in turn stimulates the parietal cells. Whether parietal cells also possess gastrin receptors of physiological significance is unclear. The aim of the present study was to localize the CCK-2 receptor cellularly and concomitantly demonstrate a gastrin receptor response (histamine release)., Methods: Fluorescein labelled cholecystokinin-8 (Fluo-CCK-8) was added to the arterial infusion to totally isolated, vascularly perfused rat stomachs to a final concentration of 130 pmol L(-1) for 1 min, either alone or along with 520 nmol(-1) CCK-8 after 10-min pre-perfusion with CCK-8. Immediately after the Fluo-CCK-8 had reached the oxyntic mucosa, biopsies were taken and the binding sites were localized by double immunohistochemistry combined with the tyramide signal amplification (TSA) technique. Venous histamine was measured before and during stimulation., Results: Fluo-CCK-8 (130 pM) evoked histamine release, and binding sites were found in the basal part of corpus mucosa, co-localized with histidine decarbocylase (HDC) immunoreactive ECL cells. No binding of Fluo-CCK was found in the mid-glandular region of corpus, dominated by parietal cells. Binding of Fluo-CCK-8 was abolished by concomitant perfusion with excess CCK-8., Conclusion: Fluo-CCK-8 given to isolated rat stomachs in a physiological concentration binds to CCK-2 receptors on ECL cells and causes histamine release, whereas no binding of Fluo-CCK-8 to parietal cells was found.

Previous studies have shown that pituitary adenylate cyclase-activating peptide (PACAP) stimulates enterochromaffin-like (ECL) cell histamine release, but its role in the regulation of gastric acid secretion is disputed. This work examines the effect of PACAP-38 on aminopyrine uptake in enriched rat parietal cells and on histamine release and acid secretion in the isolated vascularly perfused rat stomach and the role of PACAP in vagally (2-deoxyglucose) stimulated acid secretion in the awake rat. PACAP has no direct effect on the isolated parietal cell as assessed by aminopyrine uptake. PACAP induces a concentration-dependent histamine release and acid secretion in the isolated stomach, and its effect on histamine release is additive to gastrin. The histamine H2 antagonist ranitidine potently inhibits PACAP-stimulated acid secretion without affecting histamine release. Vagally stimulated acid secretion is partially inhibited by a PACAP antagonist. The results from the present study strongly suggest that PACAP plays an important role in the neurohumoral regulation of gastric acid secretion. Its effect seems to be mediated by the release of ECL cell histamine.

Background: The stomach is rich in endocrine cells, including those producing ghrelin, which is thought to play a role in the control of body growth. Omeprazole treatment is associated with hypergastrinaemia, resulting in growth of the oxyntic mucosa in general and the enterochromaffin-like (ECL) cells in particular. In the present study, we examined the effects of long-term omeprazole treatment on young male rats with respect to body growth and stomach., Methods: Male rats (24 days old) were treated with omeprazole (400 micromol/kg/day) or vehicle for 77 days. The body weight was recorded twice per week. At sacrifice, dual-energy X-ray absorptiometry (DXA) was used to assess total bone area, bone mineral content (BMC), bone mineral density (BMD) and body composition (fat and lean body mass). The lengths of the spine and the femur were recorded. The plasma concentrations of gastrin and histamine were determined by radioimmunoassays. The endocrine cells of the stomach were examined by immunocytochemistry., Results: The body weight gain was suppressed by omeprazole treatment. The bone area, BMC and BMD were reduced, while the lengths of the spine and the femur and the body composition were unchanged. Omeprazole-induced hypergastrinaemia was associated with enlargement of the oxyntic area and with hyperplasia of ECL cells but not of A-like cells and D cells. In contrast, the enterchromaffin (EC) cell density in the antrum was reduced., Conclusions: Omeprazole treatment of young male rats reduces body weight and bone mass gain. The densities of ECL cells in the oxyntic mucosa was increased and of the EC cells in the antral mucosa reduced.

ECL cells in the oxyntic mucosa of stomach control gastric acid secretion by mobilizing histamine in response to gastrin. They respond to gastrin also with hypertrophy and hyperplasia. ECL cells exhibit functional impairment upon long-term gastrin stimulation. The impairment is manifested in a gradual decline of the activity of the histamine-forming enzyme per individual ECL cell and in a failure of gastrin to mobilize histamine. The mechanism behind this impairment is unknown. In the present study, rats were treated with the proton pump inhibitor pantoprazole for 45 days to induce sustained hypergastrinemia. The ECL cells were isolated from normogastrinemic and hypergastrinemic rats and size-separated from other mucosal cells by the elutriation technique. The total ECL cell number was twofold higher in hypergastrinemic rats than in normogastrinemic rats, and most of the cells appeared in elutriation fractions where large cells predominate. The ECL cells of the different fractions were analyzed by quantitative electron microscopy. Normal-sized ECL cells from hypergastrinemic rats displayed a reduced number of secretory vesicles (probably because of degranulation) compared with normal-sized ECL cells from normogastrinemic rats. Hypertrophic ECL cells from hypergastrinemic rats had an unchanged number of secretory vesicles, supporting the view that such cells fail to respond to gastrin with degranulation. Although both normal-sized and hypertrophic ECL cells from hypergastrinemic rats contained vacuoles, those in the hypertrophic ECL cells were larger and more numerous. In addition, hypertrophic ECL cells were found to contain numerous, prominent lipofuscin bodies which are the presumed end product of crinophagia. Conceivably therefore, large vacuoles and lipofuscin bodies cause functional impairment of the hypertrophic ECL cells.

With regard to the cellular origin of bronchial squamous-cell carcinomas, there are some clinicopathologic and experimental data indicating a link between neuroendocrine (NE) bronchial tumors and the traditionally non-NE squamous-cell carcinomas. Against this background, 29 consecutively resected bronchial squamous-cell carcinomas were examined immunohistochemically (IHC) by means of the specific NE cell marker chromogranin A (CgA), using not only conventional IHC methods, but also the technique with increased sensitivity, offered by the tyramide signal amplification (TSA) procedure. Whereas none of the 29 tumors displayed CgA immunoreactive (IR) cells using the conventional IHC procedure, 10 were found to display a fine granular CgA IR in the neoplastic parenchymal cells using the TSA technique. This incidence is higher than previously reported. However, the CgA IR cells never formed any majority cell population of the neoplastic parenchyma; when present, most of them occurred as micronodules or larger confluent areas in the peripheral most undifferentiated parts of the carcinomatous sheets. Single CgA IR cells were detected only rarely in the spinocellular or keratinized areas. It can be speculated that the observations conform with the recently proposed hypothesis that there is a reservoir of NE progenitor cells in the bronchial mucosa capable of proliferation.

Background: Chromogranin A (CgA) is a sensitive marker for neuroendocrine neoplasia. Enterochromaffin-like cell hyperplasia secondary to hypergastrinemia also leads to CgA increase in blood. Treatment with inhibitors of acid secretion, atrophic gastritis and infection with Helicobacter pylori are prevalent conditions leading to hypergastrinemia. We therefore wanted to study whether concomitant determination of gastrin could increase the utility of CgA as a marker of neuroendocrine neoplasia., Methods: CgA and gastrin concentrations were determined by radioimmunoassay methods, while pepsinogen I (used to diagnose severe atrophic gastritis) was determined by a commercial immunoenzymatic assay., Results: Among 100 patients with elevated CgA, we found that 29% had hypergastrinemia. Vice versa, CgA was elevated in 23 out of 26 (88.5%) in a population of patients with hypergastrinemia. By determining pepsinogen I in blood in patients with hypergastrinemia, a proportion of them was diagnosed as having severe atrophic gastritis., Conclusion: We conclude that determination of gastrin in blood in patients with CgA elevation will increase the utility of CgA in the diagnosis of neuroendocrine tumors., (Copyright 2001 S. Karger AG, Basel)

Background: Randomised trials have shown that banding ligation is superior to sclerotherapy, requiring fewer treatment sessions to achieve variceal eradication, and giving lower rebleeding and complication rates., Material and Methods: From November 1997 through December 1999, we have treated 22 patients with bleeding oesophageal varices with endoscopic banding ligation to obliterate the varices and prevent recurrent bleeding., Results: A total of 72 banding procedures have been performed using rubber bands. The varices have been obliterated in 14 patients requiring a median of 3.5 (range 2-8) procedures, which is in good agreement with other published data. Twelve of these patients have been observed for a median of six (range 1-19) months without signs of recurrent bleeding. One patient had a bleeding four months after the last ligation procedure; the varices were obliterated six weeks before. One patient had a recurrent bleeding between the first and second banding procedure. One patient bled from an oesophageal ulcer caused by a rubber band two weeks after the procedure. Otherwise no serious complications occurred., Interpretation: On the basis of our own experiences and published studies, we propose that endoscopic banding ligation should be the method of choice for elective treatment of bleeding varices.

Neuroendocrine cells are often disclosed in human gastric adenocarcinomas and may be recognised by their immunoreactivity towards chromogranin A. However, in dedifferentiated neuroendocrine tumour cells, the chromogranin A content may be reduced making it difficult to detect with conventional immunohistochemical methods. We therefore used a sensitive signal amplification technique in order to evaluate chromogranin A immunoreactivity and thus neuroendocrine differentiation in 40 gastric adenocarcinomas. Neuroendocrine cells were visualised by means of a monoclonal chromogranin A antibody and the avidin-biotin peroxidase complex technique, without and with addition of tyramide signal amplification. Double immunohistochemistry towards chromogranin A and Ki-67 were used to disclose proliferation in the neoplastic cells. A marked increase in the number of carcinomas containing chromogranin A-immunoreactive neoplastic cells was noted when applying the tyramide signal amplification technique. In addition, the number of immunoreactive cells within each tumour increased, and in some cases almost all the neoplastic cells became immunoreactive. Chromogranin A-immunoreactive tumour cells showing signs of proliferation were found in the majority of these carcinomas. In conclusion, we have disclosed widespread immunoreactivity towards chromogranin A in a proportion of gastric adenocarcinomas when enhancing the signal with tyramide signal amplification. Neuroendocrine differentiation is thus a common finding in gastric carcinomas when using sensitive methods.

Gastrin has a general growth-promoting effect on gastric oxyntic mucosa, and a more pronounced one on the enterochromaffin-like (ECL) cell. Whether gastrin has a proliferative effect on the parietal cell lineage beyond the general effect is uncertain. Hypergastrinaemia was evoked in rats using pantoprazole (group II: 100 micromol kg-1, group III: 400 micromol kg-1) for 45 days. Plasma gastrin was 43 +/- 8 pmol L-1 (control), 283 +/- 54 pmol L-1 (group II) and 577 +/- 63 pmol L-1 (group III). Gastric mucosal cells were isolated and fractionated by elutriation centrifugation. Total cell number, percentage and number of ECL and parietal cells, and histamine were determined in each fraction. The number of mucosal cells increased 1.5-fold in both hypergastrinaemic groups. Enterochromaffin-like cell content was 2.6 +/- 0.5% (control), 6.0 +/- 0.6% (group II) and 9.0 +/- 0.8% (group III). Histamine concentration in oxyntic mucosal cells rose similarly. The size of the ECL cells was 8.5 +/- 0.1 microm (control), 10.8 +/- 0.2 microm (group II) and 12.1 +/- 0.2 microm (group III), and the increased size was confirmed by shifted distribution in elutriation fractions. Histamine per ECL cell increased with cell size. The number of parietal cells increased parallel to the total number of mucosal cells (1.5-fold). Parietal cell size and percentage, assessed by image analysis and distribution in elutriation fractions, were unchanged after pantoprazole dosing. Gastrin has a pronounced, concentration-dependent specific trophic effect on ECL cells and a general proliferative effect on gastric mucosa, including parietal cells.

Immunohistochemistry is used for in situ detection of proteins in histological slides and is now an important diagnostic tool. Due to several methodological and biological factors, conventional immunohistochemical procedures may sometimes have too low sensitivity, especially for tracing the histogenesis of malignant tumours. A few years ago, an amplification technique was introduced which greatly increased the sensitivity of some of the commonly used immunohistochemical methods. This technique permits the use of primary antibodies in significantly lower concentrations compared with the conventional methods. Alternatively, one can keep the antibody concentration unchanged and use the enhanced sensitivity to detect scarce proteins, which are not visualised by traditional immunohistochemical procedures. We present a brief description of the technique and show some examples of its use in the diagnosis of neuroendocrine carcinomas. Tyramide signal amplification might become an important supplement for the diagnosis and classification of malignant tumours.

We have identified cotton rats with a high female-predominant occurrence of spontaneous gastric carcinomas localized to the oxyntic mucosa, classified as malignant enterochromaffin-like (ECL) omas. The present study was made to further characterize these ECLomas and surrounding oxyntic mucosa, both morphologically using histochemical and immunohistochemical methods, and for gene expression by northern blot analysis. Among eight female cotton rats, three had an irregularly thickened oxyntic mucosa, increased stomach weight and a high serum gastrin level. Histopathological examination showed adenomatous hyperplasia of the thickened oxyntic mucosa with areas of an invasive neoplastic tumour. Immunohistochemistry, using the general neuroendocrine cell marker chromogranin A (CgA) and the specific ECL cell marker histidine decarboxylase (HDC), showed a considerably increased ECL cell density. These ECL cells displayed active proliferation, with hyperplasia, dysplasia and neoplasia. Parietal cells were not found in the tumour tissue. Parietal cell density was only slightly reduced in the surrounding oxyntic mucosa. The antral mucosa was histopathologically normal with a normal number of gastrin-immunoreactive cells. Likewise, somatostatin-immunoreactive cells did not show any differences in the antral and oxyntic mucosa between rats with pathological and normal oxyntic mucosa. Northern blot analysis revealed increased expression of CgA and HDC mRNA in the thickened oxyntic mucosa, whereas H(+)/K(+) ATPase mRNA was similar in the oxyntic mucosa of those with thickened and normal oxyntic mucosa. Gastrin mRNA in the antral mucosa was high in animals with thickened oxyntic mucosa. Somatostatin mRNA expression was similar in the antral mucosa of control animals and animals with a thickened oxyntic mucosa. We conclude that the spontaneous gastric carcinoma occurring in female cotton rats is an ECLoma developing secondary to hypergastrinaemia due to reduced intragastric pH. The mechanism for reduced acidity is not known, but is not gastric atrophy.

Background: Gastric ischaemia appears to be a common pathogenetic factor for stress ulcers. These ulcers occur predominantly in the oxyntic mucosa, suggesting that the acid secretory process or its stimulation is involved in the pathogenesis., Methods: We examined separately the role of the acid secretory process and gastric luminal acidity in the pathogenesis of gastric lesions using the isolated vascularly perfused acid-secreting rat stomach., Results: Pentagastrin-stimulated acid secretion induced submucosal bleeding in the oxyntic mucosa whether accompanied by perfusion of the gastric lumen with saline or a phosphate buffer at pH 7.0. On the other hand, acidity, whether endogenous or introduced by luminal perfusion, induced erosions in both the oxyntic and antral mucosa., Conclusion: It is concluded that the acid secretory process itself contributes to the particular vulnerability of the oxyntic mucosa to ischaemia. Histamine released upon stimulation of gastric acid secretion or shortage of energy due to the requirements for acid secretion may both contribute to this vulnerability. Furthermore, these findings suggest that inhibition of gastric acid secretion should be superior to antacids in preventing stress ulcers.

Inhibitors of gastric acid secretion, particular proton pump inhibitors, are effective drugs in the treatment and prophylaxis of acid-related diseases. Proton pump inhibitors are therefore prescribed widely, often for minor complaints. Gastric acidity kills swallowed microorganisms, and acid secretion must be of biological importance because it is maintained in phylogenesis. Acid secretion is controlled by feedback mechanisms, mainly via gastrin. A decrease in acidity always causes an increase in plasma gastrin. The trophic effect of gastrin leads to hyperplasia and neoplasia of the enterochromaffin-like (ECL) cell. ECL cell derived tumours in man were previously regarded as rare, and also as rather benign. It is now clear that the ECL cell gives rise to a significant proportion of gastric carcinomas. Moreover, ECL cell carcinoids secondary to hypergastrinaemia may develop into highly malignant tumours. Treatment with a proton pump inhibitor is followed by rebound acid hypersecretion and decreased efficiency of H2-blockers, thus such treatment may induce a type of physical dependence. It is therefore reasonable to be cautious and not to treat younger (< 50 years) patients for long periods of time with profound inhibitors of gastric acid secretion. Chromogranin A in the blood is a sensitive marker of the ECL cell mass, and it could be used to survey patients on long-term proton pump inhibitors.

Aims: The aims of this study were to illustrate the malignant potential of gastric enterochromaffin-like (ECL) cell carcinoids (ECLomas) associated with hypergastrinemia, and the gradual neoplastic progression of such tumours. In addition, we examined whether the tyramide signal amplification (TSA) technique could visualize immunohistochemical (IHC) neuroendocrine (NE) features in the dedifferentiated neoplastic ECL cells which were not detected by conventional methods., Methods: Conventional histopathological and IHC methods for visualizing ECL cells and cell proliferation were used in addition to the TSA technique., Observations: Our patient was followed for 5 years. During that period, her ECLoma displayed all the signs of classical tumour progression, ultimately with the appearance of metastases in the regional lymph nodes, the liver and the skin. The neoplastic ECL cells became progressively dedifferentiated with an increasing number of Ki-67 immunoreactive (IR) cell nuclei. In addition, there was a substantial decrease in argyrophil and IR NE cells that could be visualized by conventional methods. By applying the TSA technique, however, the number of IR tumour cells increased considerably., Conclusions: ECLomas secondary to hypergastrinemia should be closely followed for signs of clinical and histopathological tumour progression. Such ECLomas deserve early, active, radical surgical treatment. The TSA technique is a valuable tool for visualizing the characteristic IHC features in dedifferentiated NE cells.

Smoking is associated with endothelial dysfunction and increased plasma levels of endothelin-1. The component of tobacco smoke inducing these effects is unknown. Carbon monoxide induces hypoxia, and there is evidence of carbon monoxide acting as a local mediator in both endothelial and smooth muscle cells. The purpose of this study was to determine whether chronic carbon monoxide exposure similar to that experienced by smokers affects myocardial endothelin-1 expression. Sprague-Dawley female rats were exposed to carbon monoxide 100 ppm for one week or to 100 ppm for one week and 200 ppm for a second week. Carboxyhaemoglobin was 12+/-0.9% in the low and 23+/-1.1% in the high carbon monoxide exposure group. Endothelin-1 expression was measured by competitive reverse transcriptase polymerase chain reaction. High carbon monoxide exposure increased endothelin-1 mRNA by 54+/-12% (P<0.001) in the left ventricle and by 53+/-12% (P<0.001) in the right ventricle. In the low carbon monoxide exposure group corresponding changes were 43+/-14% (P=0.06) and 12+/-16%(P=0.29). Right ventricular weight increased by 18+/-7% (P=0.02) after high and by 16+/-5% (P=0.02) after low exposure. Left ventricular weight was elevated by 5+/-2% (P=0.05) when both exposure groups were compared to controls. We conclude that chronic carbon monoxide exposure leading to carboxyhaemoglobin levels similar to those observed in smokers increases endothelin-1 gene expression and induces myocardial hypertrophy in the rat.

As tobacco smoking has been identified as a risk factor in the development of osteoporosis, possible deleterious effects of nicotine inhalation on bone mineral density (BMD) and mechanical properties of the femur in female rats were studied. Female Sprague Dawley rats were exposed to nicotine vapour 20 hours a day 5 days a week for 2 years. The nicotine concentration in the inhaled air was kept at a level, giving a plasma nicotine concentration exceeding that of heavy smokers. Throughout the study, the nicotine-exposed rats weighed approximately 10% less than the control rats. At the end of the study the rats were anesthesized and blood was collected by heart puncture for determination of nicotine in plasma. Both femurs were resected and scanned by dual X-ray absorptiometry (DXA). There was no difference in BMD between control rats (n = 7) and nicotine-exposed rats (n = 23) (mean 0.216 +/- 0.021 g/cm(2) and 0. 210 +/- 0.014 g/cm(2), respectively (P = 0.19)). The left femur was used for mechanical testing of the shaft and the neck. No significant difference could be demonstrated in ultimate bending moment, ultimate energy absorbtion, stiffness, or deflection between the two groups. In conclusion, no negative effects of nicotine inhalation on the femurs of female rats were found.

Background: Androgens are implicated in the pathogenesis of prostatic carcinoma. We have elucidated the role of pre- and postnatal testosterone administration in the occurrence of proliferative lesions as well as neuroendocrine (NE) cells in the rat prostatic complex., Methods: Female rats were given a single dose of 9 mg testosterone enantate i.m. on day 15 of pregnancy; it gave a high testosterone exposure to the fetus in the early organogenetic period of the rat prostatic complex. One group of the male offspring was followed without further testosterone treatment; a second group received testosterone only in the pubertal period; a third group was given testosterone from puberty and throughout life (46 weeks). These groups were compared to parallel groups (1A-1C) of male offspring without a testosterone supplement in pregnancy., Results: The serum testosterone concentrations in the rats receiving testosterone were significantly higher than those of control rats. Histopathologically, the testosterone-induced proliferative lesions, mainly hyperplastic, were almost exclusively located in the dorsal lobe. Chromogranin A-immunoreactive (CgA-IR) cells were rarely found normally, but occurred more often in the proliferative lesions (P < 0.001)., Conclusions: The incidence of proliferative lesions in rats exposed to testosterone only in puberty was comparable to the incidence found in those rats receiving testosterone in puberty and throughout life. This finding may have clinical implications for young athletes, who use testosterone as an anabolic drug. The occurrence of CgA-IR cells increased in proliferative lesions in the dorsal lobe of the rat prostatic complex.

Background and Purpose: Female inbred cotton rats develop adenocarcinomas in the oxyntic mucosa. Since a female preponderance is typical for enterochromaffin-like (ECL) cell tumors, we examined such tumors for ECL cells. Gastrin plays a decisive role in ECL cell tumorigenesis, so blood gastrin concentration and gastric mucosal pH were measured., Methods: The stomachs from six female cotton rats (6 to 8 months old) were studied histologically, and at euthanasia, gastric mucosal pH was determined. Euthanasia was performed on 15 other female cotton rats of similar age for determination of blood gastrin values by radioimmunoassay (RIA) and gastric mucosal pH. Rats were classified macroscopically to have normal or thick oxyntic mucosa, with or without tumor., Results: Among the six cotton rats studied histologically, two 6-month-old rats had normal and two others had thick gastric mucosa, whereas two 8-month-old rats had thick mucosa with tumors. The ECL cells were markedly hyperplastic in all rats with thick mucosa, and ECL cells were found in the neoplastic parenchyma. All cotton rats with normal-appearing gastric mucosa had pH <2.5, whereas 14 rats with thick mucosa had pH >3.1 and hypergastrinemia., Conclusions: Gastrin may play a major role in ECL cell hyperplasia and, perhaps, in adenocarcinoma genesis.