Multifocal gastric carcinoid tumours, achlorhydria, and hypergastrinaemia

Multiple Gastric Carcinoids and Pernicious Anemia: Report of a Case

A case of pernicious anemia associated with multiple gastric carcinoids is reported. The neoplastic growth was composed of enterochromaffin-like (ECL) cells, and ECL cell hyperplasia was observed also in hyperplastic polyps, inside the fundic glands and in small nests lying in the lamina propria (microcarcinoidosis). The possible relation between pernicious anemia and ECL cell hyperplasia is discussed.

Urticaria as initial finding of a patient with carcinoid tumor

BACKGROUND

Typical carcinoid syndrome is characterized by flushing, abdominal pain and diarrhea and occurs in <10 % of carcinoid tumor patients. Very rarely, initial signs include skin manifestations. Our purpose is to highlight cutaneous manifestations in the diagnosis and assessment of a patient with atypical manifestation of type I gastric carcinoid tumor.

CASE PRESENTATION

A 50-year-old woman presented with anemia, chronic urticaria and angioedema. Urticaria was triggered principally by seafood and appeared in the first hour after. Urticaria Activity Score 7 was 24, and quality of life (CU-Q2oL) was 3.61. P. Laboratory findings showed anemia, diminished iron, ferritin, and vitamin B12, with increased gastrin and anti-parietal cell antibody levels. 15 gastric carcinoids 5 mm in diameter were observed in the greater curvature of the stomach during gastric endoscopy and confirmed by biopsy, suggesting that this patient had type I gastric carcinoids. Four additional tumors were found in the small intestine upon examination via video capsule. Endoscopic argon plasma therapy was performed. The patient experienced definitive improvement in quality of life and urticaria activity score.

CONCLUSION

This patient, whose principal symptoms were anemia, urticaria and angioedema, was found to have atypical carcinoid syndrome, with tumors located in the stomach. Allergists, immunologists, internists and primary care physicians should consider the possibility of neuroendocrine malignancies, specifically type I carcinoid tumors, when evaluating patients with urticaria, and consider screening patients with chronic urticaria for elevated anti-parietal cell antibody levels.

Autoimmune polyglandular syndrome presenting with jaundice and thrombocytopenia

OBJECTIVE

To report an uncommon presentation of a rare case of autoimmune polyglandular syndrome type IIIb in an elderly woman.

CLINICAL PRESENTATION AND INTERVENTION

A 62-year-old woman presented with anaemic symptoms and jaundice. Blood tests showed macrocytic anaemia due to vitamin B12 deficiency with Coombs negative haemolysis. A thyroid function test was consistent with hypothyroidism. Autoimmune antibody assays were positive for anti-parietal cell, anti-intrinsic factor and anti-thyroid peroxidase antibodies. A final diagnosis of autoimmune thyroiditis with pernicious anaemia, which constituted autoimmune polyglandular syndrome type IIIb, was made and the patient was treated with L-thyroxine, vitamin B12 injection and a blood transfusion. She was discharged uneventfully after a week of hospitalization.

CONCLUSION

This case showed that the presence of one autoimmune endocrine disease should prompt clinicians to look for other coexisting autoimmune diseases which may be asymptomatic despite positive autoantibodies.

Role of gastrin-peptides in Barrett's and colorectal carcinogenesis

Gastrin is the main hormone responsible for the stimulation of gastric acid secretion; in addition, gastrin and its derivatives exert proliferative and antiapoptotic effects on several cell types. Gastrin synthesis and secretion are increased in certain situations, for example, when proton pump inhibitors are used. The impact of sustained hypergastrinemia is currently being investigated. In vitro experiments and animal models have shown that prolonged hypergastrinemia may be related with higher cancer rates; although, this relationship is less clear in human beings. Higher gastrin levels have been shown to cause hyperplasia of several cell types; yet, the risk for developing cancer seems to be the same in normo- and hypergastrinemic patients. Some tumors also produce their own gastrin, which can act in an autocrine manner promoting tumor growth. Certain cancers are extremely dependent on gastrin to proliferate. Initial research focused only on the effects of amidated gastrins, but there has been an interest in intermediates of gastrin in the last few decades. These intermediates aren’t biologically inactive; in fact, they may exert greater effects on proliferation and apoptosis than the completely processed forms. In certain gastrin overproduction states, they are the most abundant gastrin peptides secreted. The purpose of this review is to examine the gastrin biosynthesis process and to summarize the results from different studies evaluating the production, levels, and effects of the main forms of gastrin in different overexpression states and their possible relationship with Barrett’s and colorectal carcinogenesis.

Successful type-oriented endoscopic resection for gastric carcinoid tumors: A case report

The standard treatment in Japan for gastric carcinoid has been gastrectomy with lymphadenectomy. This report describes the possibility of endoscopic treatment as an appropriate option for gastric carcinoid fulfilling certain conditions. A 46 year old woman underwent endoscopic mucosal resection for two 3 mm gastric carcinoids. The patient had hypergastrinemia with pernicious anemia and type A chronic atrophic gastritis, suggesting that the tumors were type I in Rindi's classification. Both tumors were located in the mucosal layer with no cellular polymorphism and were chromogranin A positive. Neither tumor recurrence in the stomach nor distant metastases have been documented during the 5 years of follow-up. Although many type I gastric carcinoids may be clinically indolent, reports on successful endoscopic treatment for this carcinoid have been scanty in the literature in Japan, presumably because of the hitherto surgical treatment stance for the disease. This report discusses how the size, number, depth and histological grading of the type I gastric carcinoid could allow the correct identification of a benign or malignant propensity of an individual tumor and how endoscopic resection could be a treatment of choice when these factors render it feasible. This stance could also obviate unnecessary surgical resection for more benign tumors.

Autoimmune gastritis in type 1 diabetes: a clinically oriented review

CONTEXT

Autoimmune gastritis and pernicious anemia are common autoimmune disorders, being present in up to 2% of the general population. In patients with type 1 diabetes or autoimmune thyroid disease, the prevalence is 3- to 5-fold increased. This review addresses the epidemiology, pathogenesis, diagnosis, clinical consequences, and management of autoimmune gastritis in type 1 diabetic patients.

SYNTHESIS

Autoimmune gastritis is characterized by: 1) atrophy of the corpus and fundus; 2) autoantibodies to the parietal cell and to intrinsic factor; 3) achlorhydria; 4) iron deficiency anemia; 5) hypergastrinemia; 6) pernicious anemia may result from vitamin B12 deficiency; and 7) in up to 10% of patients, autoimmune gastritis may predispose to gastric carcinoid tumors or adenocarcinomas. This provides a strong rationale for screening, early diagnosis, and treatment. The management of patients with autoimmune gastritis implies yearly determination of gastrin, iron, vitamin B12 levels, and a complete blood count. Iron or vitamin B12 should be supplemented in patients with iron deficiency or pernicious anemia. Whether regular gastroscopic surveillance, including biopsies, is needed in patients with autoimmune gastritis/pernicious anemia is controversial. The gastric carcinoids that occur in these patients generally do not pose a great threat to life, whereas the danger of developing carcinoma is controversial. Nevertheless, awaiting a consensus statement, we suggest performing gastroscopy and biopsy at least once in patients with autoantibodies to the parietal cell, iron-, or vitamin B12-deficiency anemia, or high gastrin levels.

CONCLUSION

The high prevalence of autoimmune gastritis in type 1 diabetic patients and its possible adverse impact on the health of the patient provide a strong rationale for screening, early diagnosis, periodic surveillance by gastroscopy, and treatment.

Review article: Pathogenesis and management of gastric carcinoid tumours

BACKGROUND

Gastric carcinoid tumours are rare, but are increasing in incidence.

AIM

To discuss tumour pathogenesis and outline current approaches to patient management.

METHODS

Review of published articles following a Pubmed search.

RESULTS

Although interest in gastric carcinoids has increased since it was recognized that they are associated with achlorhydria, to date there is no definite evidence that humans taking long-term acid suppressing medication are at increased risk. Type I tumours are associated with autoimmune atrophic gastritis and hypergastrinaemia, type II are associated with Zollinger-Ellison syndrome, multiple endocrine neoplasia-1 and hypergastrinaemia and sporadic type III carcinoids are gastrin-independent and carry the worst prognosis. Careful investigation of these patients is required, particularly to identify the tumour type, the source of hypergastrinaemia and the presence of metastases. Treatment can be directed at the source of hypergastrinaemia if type I or II tumours are still gastrin responsive and not growing autonomously. Type III tumours should be treated surgically.

CONCLUSIONS

Advances in our understanding of the pathogenesis of gastric carcinoids have led to recent improvements in investigation and management. Challenges remain in identifying the genetic and environmental factors, in addition to hypergastrinaemia, that are responsible for tumour development in susceptible patients.

Personal review: is profound acid inhibition safe?

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.

The risk of gastric carcinoma and carcinoid tumours in patients with pernicious anaemia. A prospective follow-up study

BACKGROUND

This endoscopic follow-up study was undertaken to evaluate the risk of gastric cancer (GC) and carcinoids in patients with pernicious anaemia (PA) and to analyse whether early detection of GC could be provided by regular endoscopic follow-up.

METHODS

Screening gastroscopy was performed in 71 patients with pernicious anaemia, and thereafter they were followed up with gastroscopies at 3-year intervals for a mean time of 5.8 years. Standardized incidence ratios (SIR) were calculated, the expected number being based on incidence rates in the whole Finnish population.

RESULTS

Two GCs were found during the follow-up period; one of these patients was asymptomatic and the other had abdominal symptoms. The SIR was 5.0 (95% confidence interval, 0.6-18). Eight carcinoids were detected, and all but one were removed endoscopically, and no metastases were found. The patients who had carcinoid tumours were younger at the diagnosis of PA than those who did not develop carcinoids (mean, 40 versus 55 years). Additionally, the patients with carcinoids had longer duration of PA (mean, 11 versus 5 years).

CONCLUSIONS

During the follow-up period the risk of GC was increased. The risk of gastric carcinoids seems to be very high in patients with pernicious anaemia when compared with a normal population, but they are mostly relatively benign tumours. Regular routine gastroscopic follow-up is not indicated in patients with pernicious anaemia.

Study of the population of enterochromaffin-like cells in mouse gastric mucosa after long-term treatment with ebrotidine

The possible hyperplastic effect on the mouse gastric mucosa following administration of 500 mg/kg of ebrotidine for 18 mo was investigated. The animals were taken from the study of carcinogenesis in mouse carried out with this product. Two different aspects were considered to assess such a possible hyperplastic effect. The height of the fundic and antral mucosa was microscopically measured in several points. Histologic sections obtained from standardized levels of the stomach were used. The density of argyrophil cells in the gastric mucosa has been also quantified, in order to identify enterochromaffin-like (ECL) cells, the most abundant among the cells that have this property. Grimelius' silver staining method was used to identify ECL cells. The cell count was performed under x400 magnification, and the length of mucosa examined was determined by computer-assisted image analysis. This study complements the mouse carcinogenesis study, in which no differences in tumor incidence were found between treated and control animals. The results show that administration of 500 mg/kg/day of ebrotidine for 18 mo to mice did not induce any hyperplastic effect on the gastric mucosa comprising its various cell types or any specific, diffuse, or focal hyperplasia of ECL cells.

The histopathological spectrum of type A gastritis

It has been recently shown that type A gastritis can be histologically diagnosed in the preatrophic stage. In order to evaluate whether parietal cell atrophy in AG might correlate with other histopathological findings in the antral and body mucosa, we retrospectively investigated 171 consecutive cases of histologically diagnosed preatrophic (active) or atrophic type A gastritis (H&E, Warthin-Starry). The prevalences of intestinal metaplasia (75% vs 44.4%) and micronodular hyperplasia (86.1% vs 52.4%) of endocrine cells in the oxyntic mucosa were significantly higher of parietal cell atrophy was present (p < 0.001 and p < 0.0001, respectively), whereas the prevalence of nodular lymphoid aggregates (77.8% vs 48.1%) and of Helicobacter pylori (14.3% vs 1.9%) in the oxyntic mucosa was significantly higher if parietal cell atrophy could not be detected (p < 0.001 and p < 0.01, respectively). In the antral mucosa, altered patterns of the inflammatory reaction could be demonstrated independent of the parietal cell mass possibly caused by impaired gastric acid production. Our data support the notion that the development of parietal cell atrophy in type A gastritis represents a stepwise process including initial pseudohypertrophy of these cells.

[Therapy of carcinoids of the stomach]

Carcinoids of the stomach are rare but have gained importance since the introduction of acid secretion inhibitors. The most important type is the tumor occurring in patients with chronic atrophic gastritis with and without pernicious anemia. The tumors are benign and can be treated by local endoscopic or surgical methods. Antrectomy reduces hypergastrinemia and may cause regression of the tumor. Sporadic carcinoids of the gastric antrum are malignant, however, and require radical surgical treatment.

Twenty-four-hour intragastric acidity: 300 mg ranitidine b.d., 20 mg omeprazole o.m., 40 mg omeprazole o.m. vs. placebo

BACKGROUND

There is considerable controversy about the degree of acid suppression that is optimal for the treatment of peptic disorders.

AIM

To compare the effects of three different regimens that are reported to strongly inhibit acid secretion.

METHODS

Intragastric 24-hour pH monitoring was performed in 11 healthy subjects in a randomized, multiple, cross-over, double-blind study. Each subject received four dose regimens, each for 2 weeks, in a random order. The regimens were: 300 mg ranitidine b.d., 20 mg omeprazole o.m., 40 mg omeprazole o.m., and placebo.

RESULTS

The decrease in gastric acidity during the daytime and during the total 24-hour period by all three treatments was significantly greater than after placebo; a significant difference in acid inhibition was found between ranitidine and 40 mg omeprazole, but not between ranitidine and 20 mg omeprazole, nor between the two doses of omeprazole. During the night-time the decrease in gastric acidity by all three treatments was significantly greater than after placebo; no difference was seen between the two doses of omeprazole and ranitidine. For the time of pH greater than 3 we found no statistical difference between the various acid decreasing regimens. The pH remained significantly longer above 4 after ranitidine and the two doses of omeprazole compared with placebo, and also longer above 4 after 40 mg omeprazole compared with ranitidine, but not after 20 mg omeprazole compared with ranitidine, nor after the two different doses of omeprazole.

CONCLUSIONS

Dosing with 300 mg ranitidine b.d., 20 mg omeprazole or 40 mg omeprazole is superior in gastric acid inhibition compared with placebo, when measured using 24-hour pH monitoring.

Pathophysiological effects of long-term acid suppression in man

A critical evaluation has been made of the available evidence in man of the effects of prolonged low acid states on the structure and function of the stomach. Various human models have been examined. 1. Ageing does not affect acid output from the normal male stomach, and there may be an increase in women. With progressive atrophy of the corpus mucosa, which is more frequent and rapid in patients with gastric ulcer, there is an associated loss of secretory function. Chronic gastritis and atrophy are the most important age-related changes, which in many cultures are hypothesized to develop via a prior Helicobacter pylori-related gastritis. However, H. pylori colonization of the mucosa decreases with increasing grades of gastric atrophy probably because intestinal metaplasia provides a hostile environment. Atrophy and intestinal metaplasia are associated with precancerous lesions and gastric cancer. Apparent hyperplasia of the gastric argyrophil endocrine cells is a common and spontaneous phenomenon in patients with atrophic gastritis, which in part may be related to the preferential loss of nonendocrine cells. 2. Pernicious anemia is associated with a complete lack of acid production, marked hypergastrinemia, and endocrine cell hyperplasia in the majority of patients. ECL-cell carcinoids and gastric cancer occur with a prevalence of 3-7%, and endoscopic surveillance in routine clinical practice is not warranted. 3. Gastric ECL-cell carcinoids are rare events that have been described in association with two diseases in man, pernicious anemia and Zollinger-Ellison syndrome as part of multiple endocrine neoplasia syndrome type I, and usually relate to marked hypergastrinemia and the presence of chronic atrophic gastritis with gastric antibodies or a genetic defect rather than the presence or absence of acid. Regression or disappearance of ECL-cell carcinoids, either spontaneously or after removal of the gastrin drive, has been recorded. Lymph node, and rarely hepatic, metastases are documented but death in these cases has been anecdotal. 4. Therapy with H2 antagonists may result in up to a twofold rise in serum gastrin levels but in man no endocrine cell hyperplasia has been recorded. However, the data for H2 antagonists on these aspects are very limited. There is no drug-related risk of gastric or esophageal cancer, although the incidence of the latter may be raised. Long-term treatment with omeprazole is associated with a two- to fourfold increase in gastrin levels over baseline values in one third of patients and apparent endocrine cell hyperplasia in 7% of cases overall.(ABSTRACT TRUNCATED AT 400 WORDS)

Gastric acid secretion, serum pepsinogen I, and serum gastrin in Japanese with gastric hyperplastic polyps or polypoid-type early gastric carcinoma

We determined the maximum secretion of gastric acid and the fasting serum levels of pepsinogen I and gastrin in Japanese patients with gastric hyperplastic polyps or polypoid-type early gastric carcinoma, comparing those findings with observations in control subjects. Both the maximum acid secretion and fasting levels of serum pepsinogen I were significantly lower in the patients with gastric hyperplastic polyps or polypoid-type early gastric carcinoma than in the controls. Fasting serum gastrin levels were significantly higher in the patients with gastric hyperplastic polyps than in the other two groups of subjects. These data demonstrated that the combination of hypochlorhydria, a low level of pepsinogen I, and hypergastrinemia (type-A gastritis) was common in the patients with gastric hyperplastic polyps, whereas hypochlorhydria and a low pepsinogen I without hypergastrinemia (type-B gastritis) were common in those with polypoid-type early gastric carcinoma.

Effect of short- and long-term treatment with omeprazole on cell cycle distribution in the gastric mucosa. Results of a flow cytometric study

Omeprazole may exert an effect on gastric mucosal proliferation by inhibiting gastric acid secretion and increasing serum gastrin levels. It may also influence the kinetics of endocrine cells and the oxyntic mucosa. The aim of the present study was to evaluate the cell cycle in different gastric compartments following short- (1 month) and long-term (6 months) administration of two different dosages of omeprazole by means of a flow cytometric method. We also determined serum gastrin levels at the same time. No differences in cell cycle distribution of the antrum, body, and fundus were found in the two different dosage groups after 1 month of therapy, considering the synthetic phase (S-phase) of the cell cycle. A statistically significant increase in S-phase was reported after long-term therapy in the mucosa of the fundus and body of the stomach in both groups. Gastrin levels showed no clear correlation with cell cycle distribution variables. We postulate a proliferative adaptation of the oxyntic mucosa to long-term drug administration not mediated by gastrin influence.

Effect of a somatostatin analogue (SMS 201-995) on antral gastrin cell hyperplasia and hypergastrinemia induced by a histamine H2-receptor antagonist

The effect of a somatostatin analogue, SMS 201-995 (SMS), on antral gastrin cell hyperplasia (AGH) and hypergastrinemia associated with 14-day administration of the histamine H2-receptor antagonist (H2-RA) famotidine was studied in rats. When the famotidine group was compared with the control group, the antral gastrin cell (G-cell) number was significantly increased (P < 0.01) by approximately twofold, and the serum gastrin level was significantly increased (P < 0.01) by approximately sixfold. When the famotidine+SMS group was compared with the famotidine group, the G-cell number was significantly decreased (P < 0.01) by approximately 30%, and the serum gastrin level was significantly decreased (P < 0.01) by approximately 40%. These findings suggest that SMS may be useful for inhibiting AGH and hypergastrinemia induced by long-term H2-RA administration.

Three subtypes of gastric argyrophil carcinoid and the gastric neuroendocrine carcinoma: a clinicopathologic study

BACKGROUND

Enterochromaffinlike (ECL) cell carcinoids recently observed in rats stimulated new interest in gastric endocrine tumors arising in humans.

METHODS

Paraffin-embedded sections of 55 endocrine tumor cases were stained with H&E, mucin tests were performed, and immunoperoxidase was used for detecting endocrine markers; 23 cases were also investigated ultrastructurally.

RESULTS

Forty-five argyrophil carcinoids, 9 neuroendocrine carcinomas, and 1 gastrinoma were identified. Three clinicopathologic subtypes of carcinoids were characterized: (1) twenty-eight cases, none metastatic, arose in a background of body-fundus atrophic gastritis and hypergastrinemia; (2) seven cases, 2 locally metastatic, were associated with hypertrophic gastropathy and hypergastrinemia due to multiple endocrine neoplasia/Zollinger-Ellison syndrome; and (3) ten were sporadic cases, 7 of which were deeply invasive, 6 metastatic, and 5 histologically atypical. All carcinoids showed histochemical and ultrastructural patterns of ECL cells. The 9 neuroendocrine carcinomas, all deeply invasive and metastatic, were composed of anaplastic, small- to intermediate-sized cells with high mitotic index and focal necrosis.

CONCLUSIONS

Gastrin-promoted carcinoids represent a benign or low grade tumor disease, whereas sporadic carcinoids and neuroendocrine carcinomas are life-threatening neoplasms, independent of gastrin promotion.

Pernicious anemia and subsequent cancer. A population-based cohort study

BACKGROUND

Elevated risk of cancers of the stomach, colon, and buccal cavity, as well as of lymphoma and leukemia, have been reported for patients with pernicious anemia in case reports and hospital-based and cross-sectional studies.

METHODS

A cohort of 2021 men and 2496 women living in the Uppsala health care region in Sweden, discharged with a hospital diagnosis of pernicious anemia from 1965 to 1983, was followed for 20 years for subsequent risk of cancer.

RESULTS

A total of 553 cancers were diagnosed among these patients, significantly more than expected based on cancer standardized incidence rates (SIRs) in the general population (SIR = 1.4; 95% confidence interval [CI], 1.2-1.5). Most prominent were excesses for cancer of the stomach (SIR = 2.9; 95% CI, 2.4-3.5), esophagus (SIR = 3.2; 95% CI, 1.8-5.2), and pancreas (SIR = 1.7; 95% CI, 1.2-2.4) among men and women; myeloid leukemia among men (SIR = 4.4; 95% CI, 1.8-5.2); and multiple myeloma among women (SIR = 2.5; 95% CI, 1.1-4.9). An excess of gastric carcinoid tumors also was evident in this cohort. The risk of stomach cancer was highest in the first year after diagnosis of pernicious anemia (SIR = 7.4; 95% CI, 5.3-10.1), but an increased risk persisted throughout the follow-up period. The risk of esophageal cancer also remained elevated throughout the study period, although the risk of pancreatic cancer dropped off after 5 years.

CONCLUSIONS

This study confirms the excess risk of gastric carcinoma and carcinoid tumors associated with pernicious anemia, and suggests that the susceptibility state may extend to esophageal and other cancers.

Omeprazole. Gastrin and gastric endocrine cell data from clinical studies

Gastric enterochromaffin-like cell carcinoids have been detected in rats exposed lifelong to omeprazole. By inhibiting acid secretion, omeprazole causes hypergastrinemia which, with prolonged exposure, exerts a trophic effect on enterochromaffin-like cells with eventual enterochromaffin-like cell carcinoid formation in some animals. This mechanism seems to explain the appearance of enterochromaffin-like cell carcinoids in human hypergastrinemic states, whether associated with hyperchlorhydria, eg, Zollinger-Ellison syndrome, or with hypochlorhydria, eg, pernicious anemia (nonantral atrophic gastritis). Omeprazole produces modest serum gastrin elevations in humans when monitored over a 24-hr period. Gastrin levels are markedly lower and less sustained than in the above hypergastrinemic states. Extensive gastric biopsy data from patients enrolled in long-term studies indicate that omeprazole administration is not associated with clinically significant changes in the human oxyntic endocrine cell population. Man and rat differ markedly both in their gastrin response to a given level of acid inhibition and in their response to the trophic influence of gastrin on enterochromaffin-like cells. The rat model is a false indicator of risk in man.

Trophic effects of gastrin

Gastrin is an important trophic hormone for the acid-producing part of the stomach. There is no solid evidence that gastrin is physiologically important as a trophic agent outside the stomach. The trophic effects in the stomach are manifested as an increased weight and thickness of the oxyntic mucosa and can be induced by both exogenous and endogenous gastrin--that is, in situations of long-lasting hypergastrinemia (treatment with effective antisecretagogues, partial fundectomy, or antrum exclusion). Removal of endogenous gastrin by antrectomy induces the opposite effects--that is, diminished weight and thickness of the oxyntic mucosa. Unlike all other peptide hormone-producing endocrine cells in the oxyntic mucosa, the so-called enterochromaffin-like (ECL) cells respond readily to gastrin. An acute gastrin challenge results in release of stored products from the ECL cells (such as histamine) and activation of cytoplasmic enzymes (such as histidine decarboxylase). Sustained elevation of circulating gastrin over days results in hypertrophy of the ECL cells and over weeks results in marked hyperplasia (at most a fivefold increase in the rat). The results in other species are similar but often somewhat less marked than in the rat.

Proposed mechanism of induction of gastric carcinoids: the gastrin hypothesis

Novel, powerful and long-acting inhibitors of gastric acid secretion include second generation H2-blockers and so-called proton pump inhibitors, such as omeprazole. Gastric carcinoids were found to develop in experimental animals as a consequence of continuous long-term administration of several of these highly effective anti secretory drugs. This unwanted side effect is now thought to reflect the fact (1) that pharmacological blockade of acid secretion results in hypergastrinaemia, and (2) that long-standing hypergastrinaemia gives rise to hyperplasia of certain endocrine cells, the so-called ECL cells, in the gastric mucosa. The carcinoids that develop in the rat stomach after lifelong treatment with antisecretagogues arise from the ECL cells. The proposed sequence of events is acid blockade--hypergastrinaemia--ECL cell hyperplasia--carcinoid. This concept, referred to as the gastrin hypothesis, maintains that the ECL cell hyperplasia (and possibly the carcinoids) is a consequence of long-term continuous hypergastrinaemia.

A comparison of two doses of nizatidine versus placebo in the treatment of reflux oesophagitis

Three-hundred and twenty-five patients with endoscopically verified oesophagitis entered a double-blind, randomized multicentre study that compared 300 mg nizatidine b.d., 300 mg nocte and placebo. The 6- and 12-week treatment responses were studied. Healing was defined as complete epithelialization of all oesophageal lesions. The healing rates were 40% in the 300 mg nizatidine b.d. group, 30% in the 300 mg nocte group and 26% in the placebo group at 6 weeks. The corresponding figures after 12 weeks of treatment were 50%, 44% and 34%, respectively. The healing rates were significantly different (P less than 0.05) between the high-dose nizatidine group and placebo only, both at 6 and 12 weeks. Despite a trend at both 6 and 12 weeks in favour of 300 mg nizatidine nocte compared to placebo, this was not significantly different. The most important factor for the outcome, apart from the treatment group, was the pre-entry severity of oesophagitis. The differences observed between treatment groups in healing rates, symptomatic relief, and antacid consumption appear to result mainly from the patients with moderate and severe oesophagitis upon entry. Nizatidine (300 mg) b.d. appeared to be safe and effective in the treatment of reflux oesophagitis.

Gut endocrine and neural peptides

The once exponential growth in the number of new gut endocrine peptides being discovered has become slightly slower in recent years, and expansion of the field of gut hormones has involved mainly the application of new investigative methods. Some new peptides have been described and major inroads have been made into establishing the ontogeny of gut endocrine cells, the origins and pathways of the enteric innervation, and the involvement of the diffuse neuroendocrine system as a whole in disease states. Further insight is being gained into the functional activity of the peptide cell system by studying the control, sites and rates of peptide gene expression, and the localization and characterization of peptide binding sites on target cells.

Potential hazards of long-term acid suppression

Neuroendocrine cell (carcinoid) tumours have been reported in the acid-secreting part of the stomach of rodents after long-term administration of a range of potent chemically diverse antisecretory agents. Although evidence shows a link between the sequence of acid suppression, hypergastrinaemia, and neuroendocrine cell hyperplasia, other factors are also thought to be involved in neoplastic transformation. Prolonged hypochlorhydria or achlorhydria resulting in bacterial colonization of the stomach may allow the generation of carcinogenic substances. Other as yet unidentified trophic factors may be involved in tumour formation. In view of the potential risks associated with these agents, there must be concern about the possible consequences in man of marked suppression of acid. It seems wise to limit the use of these more potent agents to situations in which conventional therapy has failed and to short-term treatment.

Atrophic gastritis and gastric carcinoid tumours

During recent decades an increasing number of case reports have pointed at a relation between atrophic gastritis type A and gastric carcinoid. This relation has now been quantitatively documented in endoscopic screening studies. Among patients with pernicious anaemia the prevalence of gastric carcinoid was 2-9%. Many of these carcinoids, however, remain subclinical. The majority are broadbased polypoid tumours. Most are situated in the gastric body or fundus. Of 95 patients with atrophic gastritis and gastric carcinoid reported in the literature, 60 (63%) had multicentric tumours and 13 (14%) lymph node and/or hepatic metastases. Microscopically, the tumours, which are frequently of the enterochromaffin-like cell type, show various structural differentiations, glandular differentiation indicating malignant potential. Purely intramucosal carcinoids have been described. The precurser lesion to such "early carcinoids", as well as to infiltrating carcinoids, is probably hyperplasia of endocrine cells in the atrophic fundic mucosa. Such hyperplasias, whether nodular or diffuse, are quantitatively related to hypergastrinaemia, which is a typical feature of antrum sparing (type A) atrophic gastritis. Most tumours can be treated endoscopically, although antrectomy with abolition of hypergastrinemia may be the definitive treatment. It seems that the risk of developing gastric carcinoid 'per se' does not justify regular gastric screening in patients with type A atrophic gastritis. However, as these patients also run an increased risk of developing several benign diseases, gastric adenocarcinoma, and probably also pancreatic malignancy, regular survey in selected cases is indicated.

Gastrointestinal carcinoid tumours. Histogenetic, histochemical, immunohistochemical, clinical and therapeutic aspects

The increased knowledge of the pathobiology of gastrointestinal carcinoid (neuroendocrine) tumours and the improved therapeutic possibilities have brought a demand for more precise diagnosis. Although the carcinoid tumours can often be tentatively recognized in routinely processed microscopic slides, their more accurate identification requires additional diagnostic procedures. General neuroendocrine markers such as the argyrophil reaction of Grimelius and immunohistochemistry with application of antibodies against chromogranin A and of neuron-specific enolase are discriminatory staining methods which are used to reveal the neuroendocrine origin of almost all highly differentiated carcinoid tumours of the gastrointestinal tract. Mid-gut carcinoids, which predominate among these tumours almost unexceptionally contain serotonin. This biogenic amine can be demonstrated by the argentaffin reaction of Masson, serotonin immunoreactively or by formalin-induced fluorescence. The characteristic staining pattern of mid-gut carcinoids is almost invariably preserved in the metastatic deposits and consequently the staining methods for identifying serotonin can also be used on metastases to reveal a primary mid-gut carcinoid. The enterochromaffin-like (ECL) cell carcinoids of the body and fundic area of the stomach often seen in association with pernicious anaemia are argyrophil with the Sevier-Munger silver stain. Other neuroendocrine tumours, viz. antral, duodenal and rectal carcinoids should be studied by a battery of relevant peptide hormone antisera for adequate diagnosis. During the last decade new peptide hormones have been found in circulation in patients with carcinoid tumours, but serotonin and urinary 5-HIAA are still the most important markers for carcinoids of the mid-gut origin. Other clinically useful tumour markers are chromogranin A + B, pancreatic polypeptide, human chorionic gonadotropin alpha and beta subunits. For localizing procedures, angiography is the most reliable investigative method for primary tumours in the gut, whereas CT-scan and ultrasound investigations are good for detection of liver metastases. During the last five years, the therapy for malignant carcinoid tumours has been considerably improved. Chemotherapy has only revealed objective response rates in about 10-30% of the patients giving median survivals from start of therapy of about 10 months. Recently treatment with alpha interferons and the new somatostatin analogue octreotide have given objective responses in 50-75% of patients with malignant mid-gut carcinoid tumours. These patients have now a median survival from start of therapy of 70 months when treated with alpha interferons. In the future new therapies will come into use such as monoclonal antibodies and perhaps also agents blocking different growth factors.

Mucosal argyrophil endocrine cells in pernicious anaemia and upper gastrointestinal carcinoid tumours

The number and density of argyrophil endocrine cells were morphometrically calculated in gastric fundal mucosal biopsy specimens taken from 64 patients with pernicious anaemia (five with gastric carcinoids, 15 with nodular argyrophil cell hyperplasia, 44 with diffuse argyrophil cell hyperplasia) and from 14 healthy controls. Similar calculations were also made on the ileal mucosa away from the tumour of 10 patients with ileal carcinoids and 10 controls. In the stomach, the argyrophil cell counts were twice as high in the patients with pernicious anaemia than in controls and the densities in the whole mucosa or in the epithelial structures were similarly three to five times higher. The cell counts in the patients showed positive correlation with the serum gastrin concentration. The patients with nodular argyrophil cell hyperplasia and gastric carcinoids formed a uniform group with the highest cell counts and serum gastrin concentrations; the difference between the groups was in the longer duration of pernicious anaemia in the patients with carcinoid tumours. On the other hand, no endocrine cell hyperplasia was seen in those with ileal carcinoids. It is concluded that fundal mucosal endocrine cells show an increase in patients with pernicious anaemia that is related to the gastrin concentration. This phenomenon may favour the development of hyperplastic endocrine cell nodules and, eventually, carcinoid tumours.

Enterochromaffin-like cell populations in human fundic mucosa: quantitative studies of their variations with age, sex, and plasma gastrin levels

The human gastric fundal mucosa contains a variety of endocrine cells, the most numerous of which are the so-called enterochromaffin-like (ECL) cells. We have studied the variations with age and sex of the ECL cell populations, utilizing an assessment based on multiple endoscopic biopsies from four groups of subjects. Plasma gastrin levels were also determined in these subjects. In males, endocrine cell densities declined with age but the ECL cell numbers in females opposed this trend. ECL cell counts showed no appreciable differences between young and old females. In older females, there was a high rate of gastritis and increased levels of circulating gastrin. Concentrations in older females (29.6 +/- 8.7 pmol/l) were higher than in both younger (less than 45 years) males (5.3 +/- 1.1 pmol/l) and older (greater than 55 years) males (6.3 +/- 0.6 pmol/l) (P less than 0.05). The plasma gastrin level was also higher in older females than in young females (13.1 +/- 4.5 pmol/l), although this difference failed to reach statistical significance. In conclusion, clinically silent gastritis, raised gastrin levels, and maintenance or rise of ECL cells numbers, in opposition to a general decrease in endocrine cells with age, appear to be features of women of more than 55 years of age. The variations in ECL cell populations reported here should be taken into account when evaluating possible pathological alterations of the stomach.

An evaluation of the safety of ranitidine during seven years daily oral administration to beagle dogs

1. Ranitidine hydrochloride was administered orally to Beagles at doses equivalent to 50 mg once daily, or 5 mg twice daily, of ranitidine base/kg for more than 7 years. 2. Apart from looseness of faeces, seen mainly after doses of 50 mg/kg and only rarely after the first year of such treatment, there were no adverse clinical effects. There were no deaths related to treatment. 3. Periodic gastroscopy revealed nothing abnormal. 4. Peak plasma levels of ranitidine occurred within 2 h of dosing; levels were proportional to the doses administered. 5. There were no major differences in fasting plasma gastrin levels between treated and untreated dogs; the expected increase occurred in response to the provision of food and, predictably, this was greater following a dose of ranitidine. 6. A normal histamine-induced gastric secretory response was demonstrated. 7. Necropsy revealed no lesions of toxicological significance. Macroscopically the stomachs appeared normal but microscopic examination showed some gastritis in both treated and control dogs. No changes in enterochromaffin-like (ECL) cells were detected. Electron microscopy showed unimpaired secretory activity of parietal cells. 8. Thus, after more than 7 years administration to beagle dogs of doses in excess of the normal daily therapeutic dose, the stomachs showed no changes attributable to treatment and their secretory capacity was unimpaired.

Calbindin immunoreactivity is a characteristic of enterochromaffin-like cells (ECL cells) of the human stomach

Immunoreactivity for the calcium binding protein, calbindin D28k has been localized in enterochromaffin-like (ECL) cells of the human stomach. The reactivity was observed with three different antisera, raised against bovine brain, primate brain, and chicken intestinal calbindin. The ECL cells were closed endocrine cells located at the bases of the oxyntic glands. They were not found in other regions of the stomach. No other gastric endocrine cells were reactive with these antisera.

Clinical presentation and prognosis of gastrointestinal carcinoid tumours

Clinical data about 104 patients with gastrointestinal carcinoids emphasized the heterogeneous nature of these tumours in different organs. The sites of the primary tumours were the stomach in 12 (11%), the duodenum in 3 (3%), the small bowel in 48 (45%), the appendix in 28 (26%), the colon in 6 (6%), and the rectum in 6 cases (6%). Gastric carcinoids were multiple in 4 (33%) and small-bowel carcinoids in 11 cases (23%). None of the gastric, duodenal, or rectal carcinoids had generated metastases, as contrasted to 34 (72%) small-bowel carcinoids. Twelve patients had symptoms of the carcinoid syndrome caused by hepatic metastases from ileal (11) or appendiceal (1) primary tumours. At least two patients with duodenal carcinoids had Zollinger-Ellison syndrome produced by the tumours. The cumulative 5-year survival rate was 91-100% for gastric, appendiceal, and rectal carcinoids, 77% for small-bowel carcinoids, and 33% for colonic carcinoids. Resectable mesenteric lymph node metastases did not affect the 5-year survival of patients with small-bowel carcinoids as compared with the tumours confined to the bowel wall. Poor prognosis was associated with hepatic metastases at the time of diagnosis. Small-bowel carcinoids remain a challenge in clinical work because of their distinct metastatic propensity and problematic diagnosis.

Review: the enterochromaffin-like cell, intragastric acidity and the trophic effect of plasma gastrin

Although enterochromaffin-like (ECL) cells form the major endocrine cell population of the non-antral stomach, they have been largely overlooked in the study of gastric disease. In the human, their product and functions are unknown, but they are associated with histamine secretion in rodents. The cells are controlled by neural and hormonal factors, the most significant of the latter being gastrin. Interest in ECL cells has been stimulated by the observation that hyperplasia of these cells, sometimes leading to formation of gastric carcinoid tumours, occurs in conditions of persistent hypergastrinaemia - for example, in response to the achlorhydria of individuals with pernicious anaemia. The advent of new highly potent inhibitors of gastric acid secretion is allowing more information to be obtained on the physiology and functions of the ECL cell. However, there is clearly a great deal more to be discovered about this enigmatic endocrine cell type.

Action of somatostatin analogue (SMS 201-995) on the growth-promoting effect resulting from sustained achlorhydria in rat gastric mucosa, with special reference to endocrine cell behaviour

We investigated whether a new long-acting somatostatin analogue (SMS 201-995) could antagonize the trophic effect induced by hypergastrinaemia, resulting from chronic omeprazole treatment, on the rat gastric mucosa and particularly on endocrine cell growth. SMS was administered concomitantly with omeprazole for 70 days. Gastric morphometric and cell proliferative parameters, gastric acid secretion and plasma gastrin levels were examined. New findings with omeprazole pointed out: (i) a trophic effect on the antral mucosa and (ii) that the increase observed in gastrin cell number was not due to stimulation of gastrin cell production by omeprazole but more likely to a prolongation of the gastrin cells' life span. As compared to omeprazole alone, simultaneous SMS administration significantly decreased the parietal cell (P less than 0.05) and gastrin cell (P less than 0.01) labelling indices, mucosal height of total glandular stomach (P less than 0.05) and antral mucosal height (P less than 0.05). It tended to lower fundic mucosal height and fundic argyrophil cell density (P less than 0.2 and P less than 0.1, respectively). SMS, in our conditions, did not accentuate the inhibitory effect of omeprazole on gastric acid secretion nor reduce high plasma gastrin levels. We conclude that SMS modestly counteracts the growth-promoting effect observed in rat gastric mucosa after prolonged omeprazole treatment.