Serum gastrin concentrations in dogs with primary hyperparathyroidism

BACKGROUND

Hypercalcemia has been associated with hypergastrinemia in humans. Hypergastrinemia could be responsible for gastrointestinal (GI) signs in dogs with primary hyperparathyroidism (PHPT).

HYPOTHESIS/OBJECTIVES

(a) Determine whether hypergastrinemia occurs in dogs with PHPT, (b) assess for potential correlations among ionized calcium (iCa), parathyroid hormone (PTH), and serum gastrin concentrations, and (c) determine whether gastrin concentrations decrease after management of PHPT.

ANIMALS

Phase 1: 151 client-owned dogs at the time of PHPT diagnosis, Phase 2: 24 dogs that underwent treatment for PHPT.

METHODS

Dogs with azotemia, concurrent disease, or those receiving acid suppressants were excluded. Twenty-four treated dogs had baseline and repeat quantification of serum gastrin, PTH, and iCa concentrations 4 weeks after treatment. The effect of treatment on gastrin, iCa, and PTH concentrations was assessed using Wilcoxon signed rank sum tests. Fisher exact testing was used to compare the proportion of dogs with hypergastrinemia in dogs with and without GI signs.

RESULTS

Twenty-seven of 151 PHPT dogs (17.9%) had increased pre-treatment serum gastrin concentrations (median, 45.0 ng/L; interquartile range [IQR], 20.0 ng/L). Gastrin concentrations were not correlated with iCa (P = .92) or PTH (P = .60). Treatment of PHPT decreased PTH (P < .001) and iCa concentrations (P < .001), but not gastrin concentrations (P = .15). The proportion of dogs with hypergastrinemia with and without GI signs did not differ (P = 1.00).

CONCLUSIONS AND CLINICAL IMPORTANCE

Mild increases in serum gastrin concentrations may be seen in dogs with PHPT, but this finding is independent of the presence of GI signs.

Establishment of a reference interval for 12-hour fasted serum gastrin concentration in adult dogs

BACKGROUND

Adherence to traditional 24-h fasting periods for serum gastrin concentration in dogs can be challenging and may delay the institution of therapies for suspected hypergastrinemia. Peer-reviewed publications regarding serum gastrin reference intervals (RI) are lacking. Hypercalcemia is associated with hypergastrinemia in people; limited data exist in dogs.

OBJECTIVE

The objective of the study was to generate a RI for a 12-h fasted serum gastrin concentration in dogs and to investigate whether correlations exist with age, weight, sex, and total calcium concentration.

METHODS

Fifty-five healthy adult dogs (>1 year of age). The screening included: medical history, physical examination, CBC (15 dogs), and serum chemistry (55 dogs). Gastrin was measured via a commercial radioimmunoassay. The RI for 12-h fasted serum gastrin concentration was calculated according to the recommendations of the American Society for Veterinary Clinical Pathology. Additionally, data were evaluated for correlation with selected variables.

RESULTS

The RI for serum gastrin following a 12-h fasting period was 15.1-78.9 ng/L with 90% confidence intervals for the lower and upper limits of 14.0-22.9 and 68.3-83.0 ng/L, respectively. A generalized linear model did not detect significant relationships between gastrin and age (P = 0.48), sex (P = 0.30), weight (P = 0.93), or total calcium concentration (P = 0.84).

CONCLUSIONS

A 12-h fasted serum gastrin concentration RI has been established. Given the limited range of serum calcium concentrations in our healthy study population, additional investigations are needed to determine the effects of hypercalcemia on serum gastrin concentrations in dogs and for any potential clinical consequences thereof.

Multiple Gastric Neuroendocrine Tumors Associated with Long-term Use of a Proton Pump Inhibitor and a Potassium-competitive Acid Blocker

A 52-year-old man who had been using a proton pump inhibitor (PPI) and a potassium-competitive acid blocker (P-CAB) for 14 years underwent esophagogastroduodenoscopy and was found to have three neuroendocrine tumors (NETs) in the gastric body. Following detailed examinations, parietal cell dysfunction was excluded, and the NETs did not meet the criteria for the Rindi classification types I-III. The lesions were ultimately considered to be associated with the long-term use of the PPI and P-CAB. We performed endoscopic submucosal dissection of the lesions, with no recurrence or new lesions noted after discontinuation of the PPI and P-CAB.

Evaluation of the effects of medium-term (57-day) omeprazole administration and of omeprazole discontinuation on serum gastrin and serum chromogranin A concentrations in the horse

BACKGROUND

Rebound gastric hyperacidity (RGH) secondary to hypergastrinemia has been suggested to contribute to the rapid recurrence of equine squamous gastric disease (ESGD) in horses after discontinuation of omeprazole.

HYPOTHESIS/OBJECTIVES

To evaluate changes in serum gastrin and chromogranin A (CgA) concentrations in response to medium-term (57-day) omeprazole treatment and after omeprazole discontinuation.

ANIMALS

Fourteen mature Thoroughbred racehorses in simulated race training.

METHODS

Horses received 2.28 g of oral omeprazole PO q24h for 57 days within a 61-day period, excluding a withholding period applied mid-protocol during which treatment was stopped as part of a concurrent study. Serum samples were collected on day 0 before omeprazole treatment, on day 1 of each week of the treatment period, and for an additional 5 weeks after discontinuation of treatment. Serum gastrin and CgA concentrations were analyzed using radioimmunoassay (RIA) and ELISA, respectively.

RESULTS

Median serum gastrin concentrations increased 2.5-fold from baseline to day 7 (P < .001) but did not increase further during the omeprazole treatment period. Median serum gastrin concentrations returned to baseline within 2 to 4 days after administration of the last dose of omeprazole. No effect of treatment or discontinuation was seen in serum CgA concentrations.

CONCLUSIONS AND CLINICAL IMPORTANCE

Serum gastrin concentrations increased in response to omeprazole treatment but returned to baseline within 2 to 4 days after the last dose of omeprazole. No effect of treatment or discontinuation was seen in serum CgA concentrations. Our results do not support the use of tapering protocols in horses.

The Effect of Proton Pump Inhibitor Use on Survival of Patients With Colorectal Cancer: A Study of a Racially Diverse Population

Introduction Proton pump inhibitor (PPI) use is increasing in the general population. Chronic PPI use can lead to hypergastrinemia, which has been purported to increase the risk of developing colorectal cancer (CRC). Several studies have failed to report any association between PPI use and the risk of CRC. However, little is known about the effect of PPI use on CRC survival. In this retrospective analysis, we studied the effect of PPI use on CRC survival in a racially diverse population. Methods Data were abstracted for 1050 consecutive patients diagnosed with CRC from January 2007 to December 2020. The Kaplan-Meier curve was created to study the effect of PPI exposure compared to no exposure on overall survival (OS). Univariate and multivariate analyses were performed to investigate predictors of survival. Results Complete data were available for 750 patients with CRC, 52.5% were males, 22.7% were Whites, 60.1% were Asians, and 17.2% were Pacific Islanders. A total of 25.6% of patients had a history of PPI use. Moreover, 79.2% had hypertension, 68.8% had hyperlipidemia, 38.0% had diabetes mellitus, and 30.2% had kidney disease. There was no difference in median OS among PPI users compared to non-users, p value=0.4. Age, grade, and stage were predictors of inferior OS. No significant association was noticed with gender, race, comorbidities, or treatment with chemotherapy. Conclusion In this retrospective analysis of a racially diverse population of CRC patients, we found that PPI use was not associated with worse OS. Until high-quality prospective data are available, physicians should not stop PPIs that are clinically indicated.

Severe Anemia Caused by Gastric Antral Vascular Ectasia and Autoimmune Gastritis

An 80-year-old man presented to our hospital with general fatigue on exertion that had gradually worsened over 6 months. His blood test revealed severe anemia, and gastroscopy revealed findings consistent with gastric antral vascular ectasia (GAVE) and autoimmune gastritis. We diagnosed the patient with severe anemia caused by GAVE and autoimmune gastritis. The present case suggested that GAVE is triggered by autoimmune gastritis, and the mechanism is likely related to hypergastrinemia. The reporting of this rare case may help elucidate the cause of GAVE, which is currently unknown.

Parietal Cell Dysfunction: A Rare Cause of Gastric Neuroendocrine Neoplasm with Achlorhydria and Extreme Hypergastrinemia

A 69-year-old woman with multiple neuroendocrine neoplasms (NENs) was referred to our hospital. Although she had extreme hypergastrinemia (11,675 pg/mL), no findings that indicated types I to III gastric NENs were found. Although gastric corpus atrophy was suspected on conventional white-light imaging, findings on magnifying endoscopy with narrow-band imaging indicated no severe atrophy. A biopsy from the background fundic gland mucosa revealed no atrophic changes, parietal cells with vacuolated cytoplasm and negative findings for H⁺K⁺-ATPase. Thus, this case was diagnosed as multiple NENs with parietal cell dysfunction. Neither progression nor metastasis has been confirmed during two-year follow-up.

Secretin Stimulation Test and Early Diagnosis of Gastrinoma in MEN1 Syndrome: Survey on the MEN1 Florentine Database

CONTEXT

Multiple endocrine neoplasia type 1 (MEN1) is a rare inherited endocrine cancer syndrome. Multiple gastro-entero-pancreatic neuroendocrine tumors (GEP-NETs) affect 30% to 80% of MEN1 patients, with the most common functioning GEP-NET being gastrinoma. Biochemical identification of hypergastrinemia may help to recognize the presence of gastrinomas before they are detectable by instrumental screening, enabling early diagnosis and start of therapy, preferably before tumor progression and metastases occurrence.

OBJECTIVE

Evaluate the effectiveness of secretin stimulation test to precociously diagnose the presence of gastrin-secreting tumors.

DESIGN

Results of secretin stimulation tests, performed between 1991 and February 2020, were retrospectively analyzed, as aggregate, in a cohort of MEN1 patients with GEP-NETs.

SETTING

Data were extracted from the MEN1 Florentine database.

PATIENTS

The study included 72 MEN1 patients with GEP-NETs who underwent a secretin stimulation test for the evaluation of gastrin secretion.

OUTCOMES

A positive secretin stimulation test was assumed with a difference between basal fasting serum gastrin (FSG) and the maximum stimulated value of gastrin over 120 pg/mL.

RESULTS

The secretin stimulation test showed a secretin-induced hypergastrinemia in 27.8% (20/72) of patients with GEP-NETs, and a positive test in 18 cases. The test allowed the identification of a positively stimulated hypergastrinemia in 75.0% (3/4) of patients who presented a basal FSG within the normal range.

CONCLUSIONS

Diagnosis of gastrinoma is complex, difficult, and controversial. Results of this study confirm that a positive secretin stimulation test allows early diagnosis of gastrinomas, even in the presence of borderline or normal levels of nonstimulated FSG.

Gastrin: From Physiology to Gastrointestinal Malignancies

Abetted by widespread usage of acid-suppressing proton pump inhibitors (PPIs), the mitogenic actions of the peptide hormone gastrin are being revisited as a recurring theme in various gastrointestinal (GI) malignancies. While pathological gastrin levels are intricately linked to hyperplasia of enterochromaffin-like cells leading to carcinoid development, the signaling effects exerted by gastrin on distinct cell types of the gastric mucosa are more nuanced. Indeed, mounting evidence suggests dichotomous roles for gastrin in both promoting and suppressing tumorigenesis. Here, we review the major upstream mediators of gastrin gene regulation, including inflammation secondary to Helicobacter pylori infection and the use of PPIs. We further explore the molecular biology of gastrin in GI malignancies, with particular emphasis on the regulation of gastrin in neuroendocrine neoplasms. Finally, we highlight tissue-specific transcriptional targets as an avenue for targetable therapeutics.

Gastrin and the Moderate Hypergastrinemias

The antral hormone gastrin potently regulates gastric acid secretion and fundic mucosal growth. Consequently, appropriate gastrin secretion and plasma concentrations are important for the early phases of digestion. This review describes as the first premise the normal biogenesis of gastrin in the antral mucosa, but also mentions the extraantral expression. Subsequently, the molecular nature and concentration levels of gastrin in serum or plasma are overviewed. Third, assays for accurate measurements of plasma or serum concentrations are commented. Finally, the problem of moderate hypergastrinemia due to Helicobacter pylori infections and/or treatment with proton-pump inhibitors (PPI) is discussed. The review concludes that accurate measurement of the true concentrations of bioactive gastrins in plasma is important. Moreover, it suggests that moderate hypergastrinemias are also essential health issues that require serious attention.

Gastric Hyperplastic Polyps after Argon Plasma Coagulation for Gastric Antral Vascular Ectasia in Patients with Liver Cirrhosis: A Case Suggesting the "Gastrin Link Theory"

We herein report a case of gastric hyperplastic polyps after argon plasma coagulation (APC) for gastric antral vascular ectasia (GAVE) in the antrum of a 65-year-old man with liver cirrhosis and hypergastrinemia induced by long-term proton pump inhibitor (PPI) use. Two years after APC therapy, endoscopy demonstrated multiple gastric polyps in the antrum and angle. A gastric polyp biopsy indicated foveolar epithelium hyperplasia, which was diagnosed as gastric hyperplastic polyps. One year after switching to an H2 blocker antagonist, endoscopy revealed that the polyps and GAVE had disappeared, with normal gastrin levels suggesting that PPI-induced hypergastrinemia had caused gastric hyperplastic polyps after APC therapy, and the polyps had disappeared after discontinuing PPIs.

Hyperemesis-induced Wernicke-Korsakoff Syndrome due to Hypergastrinemia during Long-term Treatment with Proton Pump Inhibitors

We herein report a patient with Wernicke-Korsakoff syndrome (WKS) who had neither a history of alcoholism or of history of gastric surgery. A 56-year-old woman was transferred to our hospital because of the loss of consciousness and she was diagnosed to have Wernicke encephalopathy. She showed proton pump inhibitor-induced refractory hypergastrinemia with the subsequent development of hyperemesis and a vitamin B1 deficiency.

Somatostatin receptor molecular imaging in a misdiagnosed gastrinoma case

Gastrin-secreting tumors, hypergastrinemia and severe ulcer disease form the trademarks of Zollinger-Ellison syndrome (ZES). We report a case of gastrinoma, in a patient who was misdiagnosed for almost five years. The case emphsizes the the special role of functional imaging in the personalized approach to the patient with suggestive symptomatology for NETs. Taking into account that in 80 to 100% of cases of gastroenteropancreatic (GEP) NETs are expressing somatostatin receptors, the functional imaging with radiolabeled somatostatin analogues can be used in order to improve its diagnosis, respectively the treatment of GEP NETs. In the approach to the patient with tremendous digestive symptomatology, physicians from different specialties should evaluate NETs specific markers and then insist on structural-functional complementarity, avoiding the waste of time and high cost of repeated structural investigations. The conclusion of our study is that functional imaging is mandatory in the diagnostic algorithm of gastrinoma.

Insights into Effects/Risks of Chronic Hypergastrinemia and Lifelong PPI Treatment in Man Based on Studies of Patients with Zollinger-Ellison Syndrome

The use of proton pump inhibitors (PPIs) over the last 30 years has rapidly increased both in the United States and worldwide. PPIs are not only very widely used both for approved indications (peptic ulcer disease, gastroesophageal reflux disease (GERD), Helicobacter pylori eradication regimens, stress ulcer prevention), but are also one of the most frequently off-label used drugs (25–70% of total). An increasing number of patients with moderate to advanced gastroesophageal reflux disease are remaining on PPI indefinitely. Whereas numerous studies show PPIs remain effective and safe, most of these studies are <5 years of duration and little data exist for >10 years of treatment. Recently, based primarily on observational/epidemiological studies, there have been an increasing number of reports raising issues about safety and side-effects with very long-term chronic treatment. Some of these safety issues are related to the possible long-term effects of chronic hypergastrinemia, which occurs in all patients taking chronic PPIs, others are related to the hypo-/achlorhydria that frequently occurs with chronic PPI treatment, and in others the mechanisms are unclear. These issues have raised considerable controversy in large part because of lack of long-term PPI treatment data (>10–20 years). Zollinger–Ellison syndrome (ZES) is caused by ectopic secretion of gastrin from a neuroendocrine tumor resulting in severe acid hypersecretion requiring life-long antisecretory treatment with PPIs, which are the drugs of choice. Because in <30% of patients with ZES, a long-term cure is not possible, these patients have life-long hypergastrinemia and require life-long treatment with PPIs. Therefore, ZES patients have been proposed as a good model of the long-term effects of hypergastrinemia in man as well as the effects/side-effects of very long-term PPI treatment. In this article, the insights from studies on ZES into these controversial issues with pertinence to chronic PPI use in non-ZES patients is reviewed, primarily concentrating on data from the prospective long-term studies of ZES patients at NIH.

Diagnosis of Zollinger-Ellison syndrome in the era of PPIs, faulty gastrin assays, sensitive imaging and limited access to acid secretory testing

In recent years the diagnosis of Zollinger-Ellison syndrome (ZES) has become increasingly controversial with several new approaches and criteria proposed, differing from the classical biochemical criterion of inappropriate hypergastrinemia (i.e., hypergastrinemia in the presence of hyperchlorhydria) (Table 1). These changes have come about because of the difficulty and potential dangers of stopping proton pump inhibitors (PPIs) for gastric acid analysis; the recognition than many of the current assays used to assess gastrin concentrations are unreliable; the development of sensitive imaging modalities that detect neuroendocrine tumors (NETs) including an increasing number of the primary gastrinomas; the increased use of percutaneous or endoscopic ultrasound (EUS)-directed biopsies/cytology and the general lack of availability of acid secretory testing. In this article we will discuss the basis for these controversies, review the proposed changes in diagnostic approaches and make recommendations for supporting the diagnosis of ZES in the modern era.

Pancreatic Endocrine Neoplasm Concomitant with a Complicated Endocrine History: A Case Report and Literature Review

Background: Pancreatic neuroendocrine tumors (PNETs) are rare, and metastases when present are most commonly found in the liver or the peripancreatic lymph nodes. In this study, we present a patient who developed a metastatic PNET in the liver in the setting of multiple concomitant autoimmune disorders, including pernicious anemia and atrophic gastritis with hypergastrinemia.

Case presentation: The patient is a 70-year-old woman with a history of Hashimoto's thyroiditis, thymoma, gastric carcinoid tumors, and autoimmune atrophic gastritis with pernicious anemia. She was found to have a 2 cm mass in the pancreaticoduodenal groove originating from the pancreas. A preoperative endoscopic ultrasound with fine-needle aspiration showed a well-differentiated PNET. During surgery, she was found to have multiple subcentimeter liver lesions, which on frozen section were shown to be a metastatic neuroendocrine tumor. After surgical resection, final pathology revealed a PNET with metastases to the liver. The metastatic lesions stained positive for gastrin.

Conclusion: We were only able to find one other example in the literature of a PNET occurring in association with pernicious anemia. Our patient developed a metastatic PNET in the setting of multiple autoimmune disorders, including pernicious anemia.

Rare Occurrence of Hypergastrinemia Due to Thoracic Neuroendocrine Tumor: Detection and Characterization by 68Ga-DOTATATE PET/CT

Hypergastrinemia is a prominent feature of a segment of gastroenteropancreatic neuroendocrine tumors, the gastrinomas, occurring mostly in the gastrinoma triangle. Hypergastrinemia due to a thoracic neuroendocrine tumor is a very rare occurrence, with a paucity of literature elucidating the same. We report a case of thoracic neuroendocrine tumor in a patient who had initially presented with symptoms of peptic ulcer disease of 3-y duration. On evaluation, the patient's fasting serum gastrin levels were found to be raised. Conventional imaging modalities and endoscopic evaluation did not identify the location of a possible gastrinoma or any other mass in the abdomen. In view of the hypergastrinemia, somatostatin receptor-targeted imaging with (68)Ga-DOTATATE PET/CT was undertaken and showed a somatostatin receptor-expressing paravertebral mass next to the thoracic aorta in the left lung. The mass was excised and was histopathologically suggestive of metastatic neuroendocrine tumor (MIB-1 labeling index, 2%). The present case underscores the importance of (68)Ga-DOTATATE PET/CT in both detecting and characterizing a causative lesion missed on contrast-enhanced CT, especially when the lesion is not easily amenable to biopsy.

Gastric neuroendocrine tumors: prevalence in Europe, USA, and Japan, and rationale for treatment with a gastrin/CCK2 receptor antagonist

OBJECTIVE

Gastric carcinoids (neuroendocrine tumors) arise from enterochromaffin-like cells in the gastric mucosa. Most are caused by hypergastrinemia. The objectives were to determine if their prevalence in Europe, USA and Japan meets the criteria for an orphan disease and to justify treatment with a gastrin/CCK2 receptor antagonist.

METHODS

We obtained data from European and USA cancer registries, and searched PubMed.

RESULTS

Prevalence per 10,000 population obtained from cancer registries was: median 0.32 (range 0.09-0.92) for Europe; and 0.17 for the USA, equivalent to 4812 for the whole population. A PubMed search for gastric carcinoids yielded prevalence for Japan only, which was 0.05 per 10,000 population, equivalent to 665 for the entire population. A further search for gastric carcinoids in patients with pernicious anemia (PA) or autoimmune chronic atrophic gastritis (CAG), two presentations of about 80% of gastric carcinoids, produced prevalence rates of 5.2-11%. Prevalence of PA itself was 0.12-1.9%. Data on CAG epidemiology were sparse.

CONCLUSION

Prevalence of gastric carcinoids varied widely. All sources probably underestimate prevalence. However, prevalence was below the limits required for recognition by drug regulatory authorities as an orphan disease: 5 per 10,000 population of Europe; 200,000 for the whole population of the USA; and 50,000 for the whole population of Japan. Because gastric carcinoids are an orphan disease, and nonclinical and healthy volunteer studies support treatment with netazepide, a gastrin/CCK2 antagonist, netazepide has been designated an orphan medicinal product in Europe and the USA for development as targeted treatment for gastric carcinoids.

G-cell hyperplasia of the stomach induces ECL-cell proliferation in the pyloric glands in a paracrinal manner

An inhibitory mechanism toward gastrin hypersecretion is significantly different between G-cell hyperplasia and gastrinoma despite the common clinical manifestations; hypergastrinemia and its related persistent gastric ulcers. We recenlty studied the G-cell, d-cell and ECL-cell density in a case of G-cell hyperplasia. The 70-year-old patient has been treated for persistent gastric ulcers with a markedly increased plasma gastrin (5600 pg/mL). The stomach was surgically resected because of the obstruction associated with ulcer scars. The number of G-cells in the pyloric glands was quantified on the surgical specimens and G-cell hyperplasia was histolopathologically identified. Immunostainig of histidine decarboxylate revealed the presence of ECL-cell hyperplasia in the pyloric glands and its density was significantly and positively correlated with G-cell density. Somatostatin immunoreactive cells (D-cells) increased in their number in the oxyntic glands. These results all indicated that hypersecretion of gastrin in G-cell hyperplasia could induce ECL-cell proliferation in a paracrinal manner. In addition, relatively non-prominent endocrinological features in the G-cell hyperplasia compared to gastrinoma could be also related to the paracrinal somatostatin inhibitory effects upon ECL-cells in the pyloric glands.

Hypergastrinemia

Gastrin is an important hormone of the digestive system, which assists gastric acid secretion. It may be pathologically elevated in conditions such as Zollinger-Ellison syndrome, or due to common medications such as proton pump inhibitors. In this review we provide an overview of the pathophysiology and medical causes of hypergastrinemia, diagnostic testing and clinical consequences of chronic hypergastrinemia.

Diagnosis of pernicious anemia and the risk of pancreatic cancer

OBJECTIVES

A number of studies have demonstrated a trophic effect of gastrin on pancreatic cancer cells in vitro. Pernicious anemia (PA) is a clinical condition characterized by chronic hypergastrinemia. The aim of this study was to determine if PA is a risk factor for pancreatic cancer.

METHODS

This study is a retrospective cohort study using The Health Improvement Network database, which contains comprehensive health information on 7.5 million patients in the United Kingdom from 1993 to 2009. All patients with PA in the study cohort were identified and composed of the exposed group. Each exposed patient was matched on practice site, sex, and age with up to 4 unexposed patients without PA. The outcome was incident pancreatic cancer. The hazard ratio and 95% confidence intervals were estimated using multivariable Cox regression analysis.

RESULTS

We identified 15,324 patients with PA and 55,094 unexposed patients. Mean follow-up time was similar between groups (exposed 4.31 [SD, 3.38] years, unexposed 4.63 [SD, 3.44] years). The multivariable adjusted hazard ratio for pancreatic cancer associated with PA was 1.16 (95% confidence interval, 0.77-1.76; P = 0.47).

CONCLUSIONS

There is no significant association between PA and the risk of pancreatic cancer.

Consensus diagnoses and mode of action for the formation of gastric tumors in rats treated with the chloroacetanilide herbicides alachlor and butachlor

A panel of pathologists (Panel) was formed to evaluate the pathogenesis and human relevance of tumors that developed in the fundic region of rat stomachs in carcinogenicity and mechanistic studies with alachlor and butachlor. The Panel evaluated stomach sections stained with hematoxylin and eosin, neuron-specific enolase, and chromogranin A to determine the presence and relative proportion of enterochromaffin-like (ECL) cells in the tumors and concluded all tumors were derived from ECL cells. Biochemical and pathological data demonstrated the tumor formation involved a nongenotoxic threshold mode of action (MOA) initially characterized by profound atrophy of the glandular fundic mucosa that affected gastric glands, but not surface epithelium. This resulted in a substantial loss of parietal cells and a compensatory mucosal cell proliferation. The loss of parietal cells caused a marked increase in gastric pH (hypochlorhydria), leading to sustained and profound hypergastrinemia. The mucosal atrophy, together with the increased gastrin, stimulated cell growth in one or more ECL cell populations, resulting in neoplasia. ECL cell autocrine and paracrine effects led to dedifferentiation of ECL cell tumors. The Panel concluded the tumors develop via a threshold-dependent nongenotoxic MOA, under conditions not relevant to humans.

Chronic proton pump inihibitor therapy and calcium metabolism

Proton pump inhibitors (PPIs) have been widely used since their introduction in the late 1980s because they are highly effective for acid-related conditions. However, some recent epidemiological studies have suggested a positive association between PPI therapy and the risk of osteoporotic fractures. The potential mechanisms underlying this association may be related to the physiologic effects of chronic acid suppression on calcium metabolism. First, chronic hypergastrinemia induced by PPI therapy may lead to parathyroid hyperplasia, resulting in increased loss of calcium from the bone. Second, profound gastric acid suppression may reduce the bioavailability of calcium for intestinal absorption. I will review the published evidence regarding these potential links and discuss their clinical implications.

Pancreatic neuroendocrine tumors: clinical features, diagnosis and medical treatment: advances

Pancreatic neuroendocrine tumors (pNETs) comprise with gastrointestinal carcinoids, the main groups of gastrointestinal neuroendocrine tumors (GI-NETs). Although these two groups of GI-NETs share many features including histological aspects; over-/ectopic expression of somatostatin receptors; the ability to ectopically secrete hormones/peptides/amines which can result in distinct functional syndromes; similar approaches used for tumor localization and some aspects of treatment, it is now generally agreed they should be considered separate. They differ in their pathogenesis, hormonal syndromes produced, many aspects of biological behaviour and most important, in their response to certain anti-tumour treatment (chemotherapy, molecular targeted therapies). In this chapter the clinical features of the different types of pNETs will be considered as well as aspects of their diagnosis and medical treatment of the hormone-excess state. Emphasis will be on controversial areas or recent advances. The other aspects of the management of these tumors (surgery, treatment of advanced disease, tumor localization) are not dealt with here, because they are covered in other chapters in this volume.

Gastrin increases mcl-1 expression in type I gastric carcinoid tumors and a gastric epithelial cell line that expresses the CCK-2 receptor

Elevated serum concentrations of the hormone gastrin are associated with the development of gastric carcinoid tumors, but the mechanisms of tumor development are not fully understood. We hypothesized that the antiapoptotic effects of gastrin may be implicated and have therefore investigated the role of antiapoptotic members of the bcl-2 family of proteins. AGS-G(R) human gastric carcinoma cells stably transfected with the CCK-2 receptor were used to assess changes in the expression of bcl-2 family members following gastrin treatment and the function of mcl-1 during apoptosis was investigated by use of small-interfering RNA (siRNA). Treatment of AGS-G(R) cells with 10 nM gastrin for 6 h caused maximally increased mcl-1 protein abundance. Gastrin-induced mcl-1 expression was inhibited by the transcription inhibitor actinomycin D and by the protein synthesis inhibitor cycloheximide. Downstream signaling of mcl-1 expression occurred via the CCK-2 receptor, protein kinase C, and MAP kinase pathways, but not via PI 3-kinase. Transfection with mcl-1 siRNA significantly suppressed mcl-1 protein expression and abolished the antiapoptotic effects of gastrin on serum starvation-induced apoptosis. Mcl-1 protein expression was also specifically increased in the type I enterochromaffin-like cell carcinoid tumors of 10 patients with autoimmune atrophic gastritis and hypergastrinemia. Gastrin therefore signals via the CCK-2 receptor, protein kinase C, and MAP kinase to induce expression of antiapoptotic mcl-1 in AGS-G(R) cells, and mcl-1 expression is also increased in human hypergastrinemia-associated type I gastric carcinoid tumors. Gastrin-induced mcl-1 expression may therefore be an important mechanism contributing toward type I gastric carcinoid development.

Gastric carcinoid tumors

Initially, carcinoid tumors were a curiosity for physicians and were so named because of their relatively benign behavior as compared to the more common adenocarcinomas. As medicine has evolved, our understanding and management have greatly improved. Our classification system has also become more specific. Gastric carcinoid tumors are unique in that three types have been described based upon each one's pathophysiology. In general, none of these give rise to the typical carcinoid syndrome as seen with metastatic ileal carcinoids.Type 1 gastric carcinoids represent 70% to 80% and are characterized by multiple small lesions and their association with hypergastrinemia secondary to chronic atrophic gastritis and pernicious anemia, and are less likely to metastasize. Type 2 is a rare entity, representing 5%, and is characterized by multiple small lesions, hypergastrinemia secondary to Zollinger-Ellison syndrome, and multiple endocrine neoplasia (MEN) type 1. The risk for metastasis is slightly higher than for type 1; however, overall prognosis is dependent upon the gastrinoma prognosis. Accounting for 20%, type 3 is known as sporadic gastric carcinoids in that there is no association with hypergastrinemia, chronic atrophic gastritis, or Zollinger-Ellison syndrome. These present as large solitary lesions and are often metastatic upon diagnosis. A unique feature of type 3 is its association with an atypical carcinoid syndrome that is thought to be mediated by histamine.The treatment-including medical, endoscopic, and surgical-of gastric carcinoids is dictated by the type, size, and presence of metastasis.

Long term omeprazole therapy for reflux esophagitis: Follow-up in serum gastrin levels, EC cell hyperplasia and neoplasia

AIM: To evaluate the long-term safety of omeprazole in patients of gastroesophageal reflux disease resistant to treatment with H2 receptor antagonist.

METHODS: We prospectively followed 33 patients on omeprazole therapy for severe erosive esophagitis for 5-8 years, with periodic gastrin levels, H. pylori infection, gastric biopsies for incidence of ECL cell hyperplasia, carcinoids, gastric atrophy and neoplasia. A total 185 patient follow-up years and 137 gastric biopsies were done.

RESULTS: Among the 33 patients, 36% reached their peak gastrin levels in an average of 8 mo to one year, then drifted Down slowly over 1-2 year period to just above their baseline level, 24% of the patients had a peak gastrin level above 400 ng·L^-1 and one patient had a peak level above 1000 ng·L^-1. One patient had a mild ECL cell hyperplasia which was self-limiting and did not show any dysplastic changes. Eighteen percent of patients were positive for H. pylori infection. The gastric biopsies did not show gastric atrophy, intestinal metaplasia or neoplastic changes.

CONCLUSION: In a series of 33 patients followed for 5-8 years on omeprazole therapy for severe reflux esophagitis, we did not observe any evidence of significant ECL cell hyperplasia, gastric atrophy, intestinal metaplasia, dysplasia or neoplastic changes.

The studies on the gastrin levels in the patients with renal failure

Fasting and postprandial gastrin levels were measured by radioimmunoassay in serum from 15 patients with renal failure and compared with those in 15 healthy controls. Pre- and posthemodialysis gastrin levels were also measured.

The fasting serum gastrin levels and serum gastrin response to a standard meal in the patients with renal failure were significantly higher than those in normal controls.

Fasting and meal stimulated gastrin levels were not significantly different in renal failure patients with peptic ulcer when compared with those in renal failure patients without peptic ulcer.

There were no statistically significant differences in the serum gastrin levels before and after hemodialysis in patients with renal failure.