Somatostatin receptor scintigraphy: its sensitivity compared with that of other imaging methods in detecting primary and metastatic gastrinomas. A prospective study

OBJECTIVE

To compare the sensitivity of somatostatin receptor scintigraphy done using [111In-DTPA-DPhe1]octreotide with that of other imaging methods in the localization of gastrinomas in patients with the Zollinger-Ellison syndrome.

DESIGN

Prospective study.

SETTING

Referral-based clinical research center.

PATIENTS

80 consecutive patients with the Zollinger-Ellison syndrome.

INTERVENTIONS

Conventional tumor localization studies (ultrasonography, computed tomography [CT], magnetic resonance imaging [MRI], selective angiography, and bone scanning) and somatostatin receptor scintigraphy done using [111In-DTPA-DPhe1]octreotide with single-photon emission CT imaging at 4 and 24 hours. Patients with possible liver metastases had biopsies done for confirmation, and 15 patients had exploratory laparotomies done to assess primary tumor localization.

RESULTS

Extrahepatic gastrinomas or liver metastases were identified by ultrasonography in 19% of patients, by CT in 38% of patients, by MRI in 45% of patients, by angiography in 40% of patients, and by somatostatin receptor scintigraphy in 70% of patients. Somatostatin receptor scintigraphy was as sensitive as the other tests combined (59%), and when the results of all other tests were added to the somatostatin receptor scintigraphy results, tumors were localized in 75% of patients. Among patients with a possible primary tumor, the results of ultrasonography were positive in 9%, the results of CT were positive in 31%, the results of MRI were positive in 30%, the results of angiography were positive in 28%, and the results of somatostatin receptor scintigraphy were positive in 58%. Somatostatin receptor scintigraphy was as sensitive as all of the other imaging studies combined; when the results of scintigraphy were added to the results of the other studies, possible primary tumors were identified in 68% of patients. In 24 patients who had histologically proven metastatic liver disease, sensitivities for the detection of any metastatic liver lesions were 46% for ultrasonography, 42% for CT, 71% for MRI, 62% for angiography, and 92% for somatostatin receptor scintigraphy. Somatostatin receptor scintigraphy was significantly better than all of the conventional imaging methods in the identification of gastrinomas later found at surgery (P = 0.004), but it still missed 20% of gastrinomas.

CONCLUSIONS

Somatostatin receptor scintigraphy is the single most sensitive method for imaging either primary or metastatic liver lesions in patients with the Zollinger-Ellison syndrome. Because of its sensitivity, simplicity, and cost-effectiveness, it should be the first imaging method used in these patients. For patients with negative results on somatostatin receptor scintigraphy, guidelines about the use of other imaging studies are proposed.

Determinants of metastatic rate and survival in patients with Zollinger-Ellison syndrome: a prospective long-term study

BACKGROUND/AIMS

It is unclear whether tumor location, size, or the presence of multiple endocrine neoplasia type 1 (MEN-1) alters metastatic rate and survival in patients with pancreatic endocrine tumors. The purpose of this study was to determine the prognostic factors of survival and metastatic rate in patients with Zollinger-Ellison syndrome (ZES).

METHODS

Data were analyzed from 185 consecutive patients with ZES who were followed up prospectively.

RESULTS

Liver metastases were present in 24% of patients and correlated with the size of the primary tumor. Duodenal tumors were smaller than pancreatic tumors. Liver metastases occurred more often (P < 0.00001) with pancreatic than duodenal tumors, whereas the metastatic rate to lymph nodes was not different. Survival of patients with liver but not lymph node metastases was shortened. In patients with sporadic ZES, liver metastases were more common during the initial evaluation and survival was decreased compared with patients with MEN-1; however, during follow-up, an equal percentage of patients with and without MEN-1 developed liver metastases.

CONCLUSIONS

Survival was primarily determined by the presence of liver metastases. The frequency of liver metastases depends on the size and location of the primary tumor and on the presence of MEN-1 at the initial presentation. Metastases to the lymph nodes do not depend on these factors. A benign and malignant form of ZES exists.

Discovery of a high affinity radioligand for the human orphan receptor, bombesin receptor subtype 3, which demonstrates that it has a unique pharmacology compared with other mammalian bombesin receptors

An orphan receptor discovered in 1993 was called bombesin receptor subtype 3 (BRS-3) because of 47-51% amino acid identity with bombesin (Bn) receptors. Its pharmacology is unknown, because no naturally occurring tissues have sufficient receptors to allow studies. We made two cell lines stably expressing the human BRS-3 (hBRS-3). hBRS-3 was overexpressed in the human non-small cell lung cancer cells, NCI-H1299, and the other was made in Balb 3T3 cells, which lack endogenous BRS-3. [D-Phe6,beta-Ala11,Phe13, Nle14]Bn-(6-14) (where Nle represents norleucine) was discovered to have high potency for stimulating inositol phosphate formation in both cell lines. [125I-D-Tyr6,beta-Ala11,Phe13, Nle14]Bn-(6-14) bound to both cell lines with high affinity. Neither Bn nor 14 other naturally occurring Bn peptides bound to hBRS-3 with a Kd <1000 nM. Twenty-six synthetic peptides that are high affinity agonists or antagonists at other bombesin receptors had an affinity >1000 nM. Guanosine 5'-(beta,gamma-imido)triphosphate inhibited binding to both cells due to a change in receptor affinity. These results demonstrate hBRS-3 has a unique pharmacology. It does not interact with high affinity with any known natural agonist or high affinity antagonist of the Bn receptor family, suggesting the natural ligand is either an undiscovered member of the Bn peptide family or an unrelated peptide. The availability of these cell lines and the hBRS-3 ligand should facilitate identification of the natural ligand for BRS-3, its pharmacology, and cell biology.

Identification of a unique ligand which has high affinity for all four bombesin receptor subtypes

Four subtypes of bombesin receptors are identified (gastrin-releasing peptide receptor, neuromedin B receptor, the orphan receptor bombesin receptor subtype 3 (BB3 or BRS-3) and bombesin receptor subtype 4 (BB4)), however, only the pharmacology of the gastrin-releasing peptide receptor has been well studied. This lack of data is due in part to the absence of a general ligand. Recently we have discovered a ligand, 125I-[D-Tyr6,betaAla11,Phe13,Nle14]bombesin-(6-1 4) that binds to BRS-3 receptors. In this study we investigate its ability to interact with all four bombesin receptor subtypes. In rat pancreatic acini containing only gastrin-releasing peptide receptor and in BB4 transfected BALB cells, this ligand and 125I-[Tyr4]bombesin, the conventional gastrin-releasing peptide receptor ligand, gave similar results for receptor number, affinity for bombesin and affinity for the unlabeled ligand. In neuromedin B receptor transfected BALB cells, this ligand and 125I-[D-Tyr0]neuromedin B, the generally used neuromedin B receptor ligand, gave similar results for receptor number, neuromedin B affinity or the unlabeled ligand affinity. Lastly, in BRS-3 transfected BALB cells, only this ligand had high affinity. For all four bombesin receptors this ligand had an affinity of 1-8 nM and was equal or greater in affinity than any other specific ligands for any receptor. The unlabeled ligand is specific for gastrin-releasing peptide receptors on rat pancreatic acini and did not inhibit binding of 125I-cholecystokinin octapeptide (125I-CCK-8), 125I-vasoactive intestinal peptide (125I-VIP) or 125I-endothelin to their receptors. The unlabeled ligand was an agonist only at the gastrin-releasing peptide receptor in rat acini and did not interact with CCK(A) receptors or muscarinic M3 acetylcholine receptors to increase [3H]inositol phosphates. These results demonstrate 125I-[D-Tyr6,betaAla11,Phe13,Nle14]bombesin-(6-1 4) is a unique ligand with high affinity for all subtypes of bombesin receptors. Because of the specificity for bombesin receptors, this ligand will be a valuable addition for such pharmacological studies as screening for bombesin receptor agonists or antagonists and, in particular, for investigating BRS-3 cell biology, a receptor for which no ligand currently exists.

Allelic imbalance, including deletion of PTEN/MMACI, at the Cowden disease locus on 10q22-23, in hamartomas from patients with Cowden syndrome and germline PTEN mutation

Cowden disease (CD) is a rare, autosomal dominant inherited cancer syndrome characterized by multiple benign and malignant lesions in a wide spectrum of tissues. While individuals with CD have an increased risk of breast and thyroid neoplasms, the primary features of CD are hamartomas. The gene for CD has been mapped by linkage analysis to a 6 cM region on the long arm of chromosome 10 at 10q22-23. Loss of heterozygosity (LOH) studies of sporadic follicular thyroid adenomas and carcinomas, both component tumors of CD, have suggested that the putative susceptibility gene for CD is a tumor suppressor gene. Somatic missense and nonsense mutations have recently been identified in breast, prostate, and brain tumor cell lines in a gene encoding a dual specificity phosphatase, PTEN/MMACI, mapped at 10q23.3. Furthermore, germline PTEN/MMACI mutations are associated with CD. In the present study, 20 hamartomas from 11 individuals belonging to ten unrelated families with CD have been examined for LOH of markers flanking and within PTEN/MMACI. Eight of these ten families have germline PTEN/MMACI mutations. LOH involving microsatellite markers within the CD interval, and including PTEN/MMACI, was identified in two fibroadenomas of the breast, a thyroid adenoma, and a pulmonary hamartoma belonging to 3 to 11 (27%) of these patients. The wild-type allele was lost in these hamartomas. Semi-quantitative PCR performed on RNA from hamartomas from three different tissues from a CD patient suggested substantial reduction of PTEN/MMACI RNA levels in all of these tissues. The LOH identified in samples from individuals with CD and the suggestion of allelic loss and reduced transcription in hamartomas from a CD patient provide evidence that PTEN/MMACI functions as a tumor suppressor in CD.

The human gastrin-releasing peptide receptor gene structure, its tissue expression and promoter

The human gastrin-releasing peptide receptor (hGRP-R) is aberrantly expressed in cancers of the colon, lung and prostate and mediates signals of cellular proliferation. However, the underlying mechanisms of aberrant and/or activation of hGRP-R expression are unknown. Therefore, a genomic clone is identified, the hGRP-R gene is characterized, and the hGRP-R promoter is defined. The protein coding region is divided into three exons and exon/intron splice sites occur in the proximal 2nd and distal 3rd intracellular loops of the receptor molecule. The hGRP-R locus extends over more than 27 kb and is assigned to the chromosomal band Xp22 by fluorescence in situ hybridization. With primer extension experiments, we demonstrate two major transcription start sites in gastrointestinal and breast cancer cells, located 43 and 36 bp downstream of a TTTAAA motif which is identified 407 to 402 bp upstream of the ATG start codon. The hGRP-R is found most abundantly expressed in the normal human pancreas, where four gene-specific transcripts can be detected by Northern blot analysis, whereas only two transcripts are detected in the human stomach and, very weakly, in the adrenal cortex and the brain. In contrast, the human GRP-R is not expressed in the normal human colon, lung, and prostate. Steady state hGRP-R mRNA can also be detected in some cultured cells from breast, lung, and duodenal cancer. Robust hGRP-R promoter activity is demonstrated in a duodenal carcinoma cell line that natively expresses the functional hGRP-R. Truncation studies suggest a CRE motif, located 112 bp upstream of the major transcription start site, is required to confer basal hGRP-R promoter activity in duodenal cancer cells. These studies provide the necessary data to further elucidate molecular mechanisms of aberrant hGRP-R expression in human cancers.

Loss of bombesin-induced feeding suppression in gastrin-releasing peptide receptor-deficient mice

The gastrin-releasing peptide receptor (GRP-R) is one of three members of the mammalian bombesin subfamily of seven-transmembrane G protein-coupled receptors that mediate diverse biological responses including secretion, neuromodulation, chemotaxis, and growth. The X chromosome-linked GRP-R gene is expressed widely during embryonic development and predominantly in gastrointestinal, neuronal, and neuroendocrine systems in the adult. Surprisingly, gene-targeted mice lacking a functional GRP-R gene develop and reproduce normally and show no gross phenotypic abnormalities. However, peripheral administration of bombesin at dosages up to 32 nmol/kg to such mice had no effect on the suppression of glucose intake, whereas normal mice showed a dose-dependent suppression of glucose intake. These data suggest that selective agonists for the GRP-R may be useful in inducing satiety.

Ability of various bombesin receptor agonists and antagonists to alter intracellular signaling of the human orphan receptor BRS-3

Bombesin (Bn) receptor subtype 3 (BRS-3) is an orphan receptor that is a predicted member of the heptahelical G-protein receptor family and so named because it shares a 50% amino acid homology with receptors for the mammalian bombesin-like peptides neuromedin B (NMB) and gastrin-releasing peptide. In a recent targeted disruption study, in which BRS-3-deficient mice were generated, the mice developed obesity, diabetes, and hypertension. To date, BRS-3's natural ligand remains unknown, its pharmacology unclear, and cellular basis of action undetermined. Furthermore, there are few tissues or cell lines found that express sufficient levels of BRS-3 protein for study. To define the intracellular signaling properties of BRS-3, we examined the ability of [D-Phe6,beta-Ala11,Phe13, Nle14]Bn-(6-14), a newly discovered peptide with high affinity for BRS-3, and various Bn receptor agonists and antagonists to alter cellular function in hBRS-3-transfected BALB 3T3 cells and hBRS-3-transfected NCI-H1299 non-small cell lung cancer cells, which natively express very low levels of hBRS-3. This ligand stimulated a 4-9-fold increase in [3H]inositol phosphate formation in both cell lines under conditions where it caused no stimulation in untransfected cells and also stimulated an increase in [3H]IP1, [3H]IP2, and 3H]IP3. The elevation of [3H]IP was concentration-dependent, with an EC50 of 20-35 nM in both cell lines. [D-Phe6,beta-Ala11,Phe13,Nle14]Bn-(6-14) stimulated a 2-3-fold increase in [Ca2+]i, a 3-fold increase in tyrosine phosphorylation of p125(FAK) with an EC50 of 0.2-0.7 nM, but failed to either stimulate increases in cyclic AMP or inhibit forskolin-stimulated increases. None of nine naturally occurring Bn peptides or three synthetic Bn analogues reported to activate hBRS-3 did so with high affinity. No high affinity Bn receptor antagonists had high affinity for the hBRS-3 receptor, although two low affinity antagonists for gastrin-releasing peptide and NMB receptors, [D-Arg1,D-Trp7,9, Leu11]substance P and [D-Pro4,D-Trp7,9,10]substance P-(4-11), inhibited hBRS-3 receptor activation. The NMB receptor-specific antagonist D-Nal,Cys,Tyr,D-Trp,Lys,Val, Cys,Nal-NH2 inhibited hBRS-3 receptor activation in a competitive fashion (Ki = 0.5 microM). Stimulation of p125(FAK) tyrosine phosphorylation by hBRS-3 activation was not inhibited by the protein kinase C inhibitor, GF109203X, or thapsigargin, alone or in combination. These results show that hBRS-3 receptor activation increases phospholipase C activity, which causes generation of inositol phosphates and changes in [Ca2+]i and is also coupled to tyrosine kinase activation, but is not coupled to adenylate cyclase activation or inhibition. hBRS-3 receptor activation results in tyrosine phosphorylation of p125(FAK), and it is not dependent on activation of either limb of the phospholipase C cascade. Although the natural ligand is not a known bombesin-related peptide, the availability of [D-Phe6,beta-Ala11, Phe13,Nle14]Bn-(6-14), which functions as a high affinity agonist in conjunction with hBRS-3-transfected cell lines and the recognition of three classes of receptor antagonists including one with affinity of 0.5 microM, should provide important tools to assist in the identification of its natural ligand, the development of more potent selective receptor antagonists and agonists, and further exploration of the signaling properties of the hBRS-3 receptor.

Prolonged hypergastrinemia does not increase the frequency of colonic neoplasia in patients with Zollinger-Ellison syndrome

Whereas considerable experimental evidence suggests chronic hypergastrinemia can increase the occurrence of colonic neoplasia, the risks in man remain unclear. Zollinger-Ellison syndrome (ZES) is associated with marked plasma elevation of all forms of gastrin and, because of its prolonged course, has been shown to be an excellent model disease to study the effects of chronic hypergastrinemia in man. To determine whether profound chronic hypergastrinemia affects the occurrence of colonic dysplasia and neoplasia, 97 consecutive patients with ZES were studied. All patients underwent colonoscopic examination to the cecum, and the location, size, and type of polyps/tumors were determined. The patients had a mean fasting gastrin level 31 times above normal and a mean disease duration of 10 years; 17/97 (18%) had adenomatous polyps, 67/97 (69%) no adenomatous polyps, and 2/97 (2%) had colonoscopy and/or autopsy studies fo asymptomatic controls. Stratification by age or gender, presence of MEN-I, tumor extent, and duration of degree of hypergastrinemia did not increase prevalence. This study shows that despite prolonged, profound hypergastrinemia, no increased rate of colonic neoplasia (polyps or cancer) was noted. These data suggest that the development of hypergastrinemia secondary to continuous use of H+,K+-ATPase inhibitors for as long as 10 years is unlikely to cause an increased risk of developing colonic neoplasia in man.

Metastatic gastrinomas: localization with selective arterial injection of secretin

PURPOSE

To evaluate localization of hepatic metastases with the intraarterial secretin injection test in Zollinger-Ellison syndrome (ZES).

MATERIALS AND METHODS

Results in 74 patients with ZES (aged 15-70 years) were retrospectively studied. All patients had undergone computed tomography (CT), magnetic resonance (MR) imaging, ultrasound, abdominal angiography, and an intraarterial secretin test, in which venous blood is sampled periodically after injection of secretin.

RESULTS

Twenty-two patients had liver metastases. An increase in venous gastrin concentration of at least 25% at 20 seconds or 50% at 30 seconds after injection indicated a positive result. Results were positive in 41% of patients with and 2% without liver metastases (P < .0001). Sensitivity of the intraarterial secretin test was 41%; of CT and ultrasound, 64%; and of MR imaging and angiography, 77%. Intraarterial secretin test results assisted in clinical management in 22% of patients.

CONCLUSION

With the criteria developed, the intraarterial secretin test had high specificity but low sensitivity. It should be used when imaging results are unclear.

Studies on the interrelation between Zollinger-Ellison syndrome, Helicobacter pylori, and proton pump inhibitor therapy

BACKGROUND & AIMS

The interrelation between Helicobacter pylori infection and proton pump inhibitor therapy in patients with Zollinger-Ellison syndrome is unknown. The aim of this study was to evaluate the influence of these factors on parameters of Zollinger-Ellison syndrome.

METHODS

Prevalence of H. pylori was determined by biopsy and antibody testing in 84 patients. The influence of H. pylori status on clinical and laboratory parameters of Zollinger-Ellison syndrome was evaluated. Seroconversion after surgery was assessed retrospectively in infected patients.

RESULTS

The prevalence of H. pylori exposure was 23% (10% with active infection). Acid output was higher in H. pylori-negative patients, but other clinical and biochemical parameters did not differ. Parameters were also similar for patients determined to be H. pylori positive by histology or antibody testing alone. Seroconversion rates did not differ between those rendered or not rendered disease free despite a significant reduction in acid output.

CONCLUSIONS

H. pylori infection is not a risk factor for peptic ulceration in patients with Zollinger-Ellison syndrome. The prevalence is lower than in the general population and much lower than for patients with idiopathic peptic ulcer disease. Long-term omeprazole therapy in H. pylori-positive patients with Zollinger-Ellison syndrome may-lead to a reduction in parietal cell mass.

The clinical and radiological features of tuberculosis in adolescents

This retrospective review of clinical records and chest radiographs (CR) of adolescents aged 10-18 years was designed to determine age and sex differences in the clinical and radiological features of adolescent tuberculosis (TB). Records of adolescents who were admitted to Brooklyn Hospital for Chest Diseases (BCH) or who were treated at local authority health clinics were screened. Data from 324 adolescents (male:female ratio 1:1.2) were studied. Intra-thoracic lesions were present on CR in 306 (94%). Primary TB with mediastinal adenopathy was present in 32 (10%). Cavitation was present in 180 (56%), 16% at 10 and 73% at 18 years of age. Cavitation occurred in 55% of males and in 56% of females with increasing frequency from 15 years of age in the former and from age 14 in the latter. Microbiological confirmation of diagnosis was obtained in 254 (78%) cases, 52% in those aged 10-13 years and 86% in those > or = 14 years. Pleural effusion was present in 42 (13%), 26 males and 16 females (p < 0.05). Thirteen (7%) of the 182 hospitalized adolescents and 27 (19%) of the ambulant group did not complete therapy. The nature of tuberculous disease in adolescents changed dramatically with increasing age.

A prospective study of the effectiveness of low dose omeprazole as initial therapy in Zollinger-Ellison syndrome

BACKGROUND

The proton pump inhibitors (omeprazole and lansoprazole) are the drugs of choice for the medical management of gastric acid hypersecretion in Zollinger-Ellison syndrome (ZES). These drugs are safe for long-term therapy but are acid-labile and high doses are expensive. The recommended starting dose of omeprazole is 60 mg/day. However, it has been shown in recent studies that the maintenance dose of omeprazole could be safely reduced to 20 mg once or twice a day in more than two-thirds of patients with ZES. The purpose of this study is to determine if an initial starting dose of omeprazole 20 mg/day is safe and effective in patients with ZES.

METHODS

Forty-nine consecutive patients with ZES being treated with ranitidine for at least 2 weeks were admitted to the NIH. Omeprazole 20 mg was started on day 1 of the admission and ranitidine discontinued 4 h after the first dose. Gastric acid output was measured for 1 h prior to the next omeprazole dose on day 2, then on day 3 if the value was > 10 mmol/h on the previous day. If acid-peptic symptoms developed or the gastric acid output remained > 10 mmol/h on day 3, the patient was considered to have failed omeprazole 20 mg/day initial therapy and the dose titrated daily to achieve adequate control of acid-peptic symptoms and gastric secretion.

RESULTS

In 33 of the 49 patients (68%) omeprazole 20 mg/day was successful as initial therapy. Sixteen patients (32%) failed this initial omeprazole dose (eight patients owing to persistent peptic symptoms and eight patients owing to inadequate acid control). The final daily omeprazole dose required in these patients was 40 mg in eight patients (16%), 60 mg in one patient (2%) and 80 mg in seven patients (14%). Basal acid output (BAO) was the only clinical or laboratory feature that was significantly different between the two groups in which low dose initial omeprazole therapy was or was not successful; all patients with basal acid output < 20 mmol/h had a successful outcome.

CONCLUSIONS

Because of the need to rapidly control gastric acid hypersecretion owing to the high risk of complications from peptic ulcer disease, patients with ZES should continue to be started on omeprazole 60 mg/day and the dose adjusted by acute titration methods as is currently recommended. After a maintenance dose is established, attempts should be undertaken to reduce the dose to 20 mg/ day once or twice a day. Only the minority of patients with ZES in whom basal acid output is known to be < 20 mmol/h (20% of patients) should be started on a low initial omeprazole dose.

Somatostatin receptor subtypes mediate contractility on human colonic smooth muscle cells

This study demonstrates the expression of functional somatostatin receptor (sstr) subtypes in human circular and longitudinal colonic smooth muscle cells (SMC). Native somatostatin (SS) and sstr subtype-specific analogues were used to characterize the sstr subtypes present in both cell types by contraction/relaxation studies. Qualitative and quantitative mRNA analysis and immunohistochemistry of sstr subtypes were also carried out. sstr subtype 2 mRNA was expressed in circular SMC, and various levels of subtypes 1, 2 and 3 mRNA were expressed in longitudinal colonic SMC. Native SS and each subtype-specific analogue exerted a modest, but significant, contraction, although inhibition of carbachol-induced contraction (relaxation) was the main effect on SMC from both layers. CH-288, a sstr subtype 1-specific analogue, and octreotide, a sstr subtype 2-specific analogue, were the most effective relaxant analogues on longitudinal and circular SMC, respectively. sstr subtypes display a distinct expression pattern on human colonic SMC; on circular SMC, subtype 2 is the only sstr, whereas sstr subtypes 1, 2 and 3 are expressed on human SMC isolated from the longitudinal layer. The contractile effects of SS are mediated through sstr subtype 2 and sstr subtype 1 on circular and longitudinal human colonic SMC, respectively.

Management of the Zollinger-Ellison syndrome in pregnancy

OBJECTIVE

There is almost no information on the management of patients with functional pancreatic endocrine tumors such as Zollinger-Ellison syndrome during pregnancy. The purpose of this study was to develop an approach for the management of such cases during pregnancy on the basis of experience with five recent cases.

STUDY DESIGN

Five women with Zollinger-Ellison syndrome who had seven pregnancies were the subject of this study. Each patient had an initial evaluation to confirm the diagnosis and to establish gastrinoma location and for the presence or absence of multiple endocrine neoplasia type I. In patients with Zollinger-Ellison syndrome diagnosed before conception, various medical or surgical treatments were established before conception and were used to control acid secretion throughout the pregnancy. The presence of upper gastrointestinal symptoms during pregnancy, maternal and fetal complications, gender, and weight of the infant were determined in all cases. Acid control was determined in four of the five patients during six pregnancies.

RESULTS

The interval between the onset of Zollinger-Ellison syndrome and the subsequent pregnancy varied from 0.6 to 9.9 years (mean 6.9 +/- 1.7 years). Zollinger-Ellison syndrome was unrecognized before pregnancy in two patients (40%); it was diagnosed between 0.2 and 2.4 years after the pregnancy. In three patients the time of diagnosis varied from 2.6 to 9 years before pregnancy. All patients had symptoms from gastric hypersecretion and elevated fasting serum gastrin levels that varied from 20% above normal to 37-fold above normal with mean of 2536 pg/ml (range 124 to 6970 pg/ml). Four of the five patients (80%) had positive secretin and calcium provocative tests. Two patients had multiple endocrine neoplasia type I. The five patients had seven pregnancies. Acid secretion was treated during pregnancy with antacids only (one patient), ranitidine alone (one patient), prior curative gastrinoma resection (one patient, two pregnancies), prior parietal cell vagotomy with incomplete tumor resection (one patient, two pregnancies), and prior parathyroidectomy and use of ranitidine in a patient with multiple endocrine neoplasia type I. In five pregnancies in three of the cases, no gastric antisecretory medications were needed during pregnancy. The mean acid secretion during pregnancy was 11.9 mEq/hr (range 0 to 42 mEq/hr). In the two cases with poor acid control and unrecognized Zollinger-Ellison syndrome mild fetal complications occurred.

CONCLUSIONS

It is possible for patients with Zollinger-Ellison syndrome to have pregnancies that are not complicated by gastric acid hypersecretion. If the Zollinger-Ellison syndrome is diagnosed before pregnancy, curative resection with parietal cell vagotomy may obviate the need for gastric antisecretory drugs. If metastases are present or the diagnosis of Zollinger-Ellison syndrome is made after conception, ranitidine in the lowest possible dose should be used to control acid secretion. If acid secretion in uncontrolled, the dose may be increased or omeprazole may be used.

Helicobacter pylori infection. A reversible cause of hypergastrinemia and hyperchlorhydria which may mimic Zollinger-Ellison syndrome

The present report describes two patients with fasting hypergastrinemia, gastric acid hypersecretion, and Helicobacter pylori gastritis. Provocative testing for Zollinger-Ellison syndrome was negative and imaging studies did not demonstrate an intra-abdominal mass. Following eradication of the Helicobacter pylori infection, the fasting hypergastrinemia resolved in both patients and in one patient the gastric acid hypersecretion also resolved. The implications of this case on the differential diagnosis of Zollinger-Ellison syndrome are discussed.

Structure and chromosomal localization of the mouse bombesin receptor subtype 3 gene

Bombesin (BN)-like peptides/neurotransmitters mediate a broad range of physiological funtions in the gastrointestinal tract and the central nervous system through binding to their specific, high-affinity mammalian bombesin receptors. This family of heptahelical, G-protein coupled receptors includes the gastrin-releasing peptide receptor (GRP-R, or bb2), neuromedin B receptor (NMB-R, or bb1), and the bombesin receptor subtype 3 (BRS-3, or bb3). The tissue distribution of BRS-3 is quite dissimilar compared to the other two BN receptors, GRP-R and NMB-R, and a natural ligand for BRS-3 is currently unknown. Nothing is known about mechanisms regulating BRS-3 gene expression and possible association with disease. To gain insight into the underlying structure and chromosomal localization of the BRS-3 genes, bacteriophage P1 genomic clones, harboring the genes for the human and mouse BRS-3, respectively, were isolated and their structure and chromosomal localizations determined. The protein-coding region of both genes is divided into three exons and spans approximately 5kb. The loci of the BRS-3 genes were mapped to a syntenic region of the human (Xq25) and mouse (XA7.1-7.2) X-chromosome, respectively. The structural data of the BRS-3 genes derived from this study will permit future investigations of the mechanisms regulating their expression.

Molecular organization of the mouse gastrin-releasing peptide receptor gene and its promoter

The murine gastrin-releasing peptide receptor (mGRP-R) is a member of the G protein-coupled receptor family and mediates important physiological actions of its specific ligand, the gastrointestinal hormone/neurotransmitter GRP, including mitogenic properties in the mouse Swiss 3T3 fibroblasts. Glucocorticoids and increases in intracellular cAMP are reported to alter GRP-R gene transcription, but the molecular basis for these effects is unknown. To begin to identify possible gene regulatory mechanisms that are responsible for modifying mGRP-R expression, we determined its structure and investigated its basal promoter activity. We isolated and characterized genomic bacteriophage P1 clones encoding the mouse gastrin-releasing peptide receptor (mGRP-R). By DNA sequencing and Southern blot analyses, we determined the protein coding region to be contained in three exons interrupted by two introns 20 and 2kb in length. The open reading frame of the putative GRP-R gene encodes for a 384-amino-acid protein which demonstrates 48% identity with the mouse BRS-3 protein and 53% identity with the mouse NMB-R protein. The mGRP-R gene locus extends over 29kb and was mapped to the X-chromosome (DXMit20) utilizing a minisatellite polymorphism in the 5' UTR and by fluorescent in-situ hybridization (FISH). In Swiss 3T3 cells, which natively express mGRP-R, two gene-specific mRNA species of 3 and 7kb can be detected by Northern blot analysis. With RNase protection assays, and independently with inverse PCR of 5' RACE clones, common mRNA initiation sites were identified clustered between 21 and 61bp downstream of a TTTAAA motif, which is located 450bp upstream of the ATG translation start site. However, different polyadenylation sites are utilized. A 2kb genomic DNA fragment extending from 2147 to 141 bases 5' to the ATG translation start was cloned into a luciferase reporter plasmid and shown to contain promoter activity in Swiss 3T3 and COS-7 cells. Progressive promoter truncations and mutations of a cyclic AMP response element (CRE) located 83bp upstream of the TTTAAA motif demonstrate that transcriptional mGRP-R activation in Swiss 3T3 cells only occurs when both the TTTAAA motif and the intact CRE site are retained. With the availability of the full structure of the mGRP-R gene and the minimal promoter sequences reported in this study, it will be possible in future studies to investigate the molecular basis for transcriptional regulation of the mGRP-R gene by glucocorticoids, cAMP and other factors.

The gastrin-releasing peptide receptor is differentially coupled to adenylate cyclase and phospholipase C in different tissues

Recent studies suggest that in some tissues GRP receptor activation can both stimulate phospholipase C and the adenylate cyclase pathway and that activation of the latter pathway may be important in mediating some of its well-described growth effects. However, other studies suggest GRP-R may not be coupled to adenylate cyclase. To investigate this possibility, in the present study we determined the coupling of the GRP receptors to each pathway in mouse, rat, and guinea pig pancreatic acini and compared it to that in mouse Swiss 3T3 cells and human SCLC cells, all of which possess well-characterized GRP receptors. Moreover, we tested the effect of PKC activation on the ability of GRP-related peptides to increase cAMP accumulation in these tissues. Changes in cAMP levels were determined with or without IBMX present, with or without forskolin, or both to amplify small increases in cAMP. In mouse, rat and guinea pig pancreatic acini, murine Swiss 3T3 cells and human SCLC cells, GRP-related peptides caused a 600%, 500%, 250%, 300% and 60% increase, respectively, in [3H]IP with 1-3 nM causing a half-maximal effect. In murine Swiss 3T3 cells, IBMX, forskolin, and IBMX plus forskolin caused a 300%, 3500% and 10500% increase in cAMP, respectively. GRP-related peptides and VIP caused an additional 70% increase in cAMP with GRP causing a half-maximal (EC50) increase in cAMP at 2.1 +/- 0.5 nM, which was not significantly different from the EC50 of 3.1 +/- 0.9 nM for increasing [3H]IP in these cells. GRP-related peptides did not stimulate increases in cAMP in mouse, rat or guinea pig pancreatic acini or in SCLC cells either alone, with IBMX or forskolin or both. However, in pancreatic acini IBMX, forskolin or both increased cAMP 3 to 8-, 10 to 500-, and 100 to 1000-fold increase and the addition of VIP caused an additional 20-, 2-, and 3-fold increase in cAMP in the different species. In mouse pancreatic acini with TPA alone or IBMX plus TPA, neither bombesin nor GRP increased cAMP. Furthermore, in mouse pancreatic acini, neither TPA nor TPA plus IBMX altered basal or VIP-stimulated increases in cAMP. In mouse Swiss 3T3 cells TPA significantly increased cAMP stimulated by Bn, GRP or VIP. These results demonstrated that GRP receptor activation in normal tissues from three different species and a human tumoral cell line do not result in adenylate cyclase activation, whereas in Swiss 3T3 cells it causes such activation. The results suggest that the difference in coupling to adenylate cyclase is likely at least partially due to a difference in coupling to an adenylate cyclase subtype whose activation is regulated by PKC. Therefore, the possible growth effects mediated by this receptor in different embryonic or tumoral cells through activation of adenylate cyclase are not likely to be an important intracellular pathway for these effects in normal tissues.

Expression of somatostatin receptor subtypes on guinea pig gastric and colonic smooth muscle cells

In vivo and in vitro studies have demonstrated that somatostatin can influence motility and smooth muscle contractility of the stomach and colon. Recent studies have proposed that some of these effects may be mediated by somatostatin receptors (sst) directly on the smooth muscle cells. If this is correct, the sst receptor subtypes that are present are unknown. This study aimed to resolve these points. Because nucleotide sequences of guinea pig sst genes are unknown, we used sst subtype-specific primers based on comparisons of human and rat sst subtypes and performed RT-PCR of DNase I-treated total RNA from guinea pig total brain. PCR products were cloned in pCR II and sequenced and showed 87% (sst(1)), 90% (sst(2)), 90% (sst(3)), 99% (sst(4)), and 80% (sst(5)), respectively, nucleotide homology to the same region (transmembrane 4-6) of the human sst genes. Homology to rat sequences were lower. PCR products were obtained from first-strand cDNA derived from DNase I-treated RNA from dispersed guinea pig gastric and colonic smooth muscle cells. In gastric and colonic smooth muscle cells, we detected sst(1)-sst(3) and sst(5), and all were confirmed by sequencing. The presence of sst(4) was shown by Southern blot analysis and hybridization with a guinea pig sst(4)-specific primer. RT-PCR from cultured colonic and gastric smooth muscle cells devoid of any neural elements gave identical results. These results demonstrate that in the guinea pig all five sst subtypes are present directly on gastric and colonic smooth muscle cells. Previous studies have suggested that a predominant sst(3) subtype on gastric and a sst(5) subtype on colonic muscle cells mediated somatostatin's contractile effects, but the finding here that all five sst subtypes exist on both of these cells suggests that other sst subtypes have only a small or no contractile effect, sst subtypes in guinea pig have a different pharmacological profile from rat or human sst, or these other sst subtypes have some yet undescribed physiological function in muscle cells.

Case report: psychosis associated with hepatitis B

An acute disintegrative disorder in a child with acute hepatitis B virus (HBV) infection is described. Both hepatitis B surface antigen (HBsAg) and HBV-DNA were detected in cerebrospinal fluid (CSF) by means of enzyme-linked immunosorbent assay (ELISA) and the polymerase chain reaction (PCR) technique respectively. A markedly elevated level of CSF adenylate kinase (AK), which normalised as the patient recovered spontaneously, suggested an organic brain disorder. Demonstration of intra-blood-brain barrier production of IgG supported the possibility of local infection by HBV within the central nervous system.