Search

In 2007 the Italian COM.E.T.A. (COMorbidities Evaluation and Treatment in Acromegaly) study group started to assess the application in a clinical setting of the Versailles criteria for management of acromegaly complications by a first questionnaire focusing on cardiovascular co-morbidities. A further questionnaire on sleep apnea syndrome (SAS) was delivered by the COM.E.T.A. study group to 107 endocrine centers in Italy. The results of our survey suggest that SAS is a well-known comorbidity even if its estimated prevalence is lower than in the literature. Polysomnography is the preferred tool for diagnosis. Control of SAS is considered relevant both for quality of life and co-morbidities. Continuous positive airway pressure is the cornerstone of therapy, but patients' acceptance may be critical. Control of GH/IGF-I secretion is important to improve SAS. Management of SAS requires cooperation between specialists. ©2011, Editrice Kurtis.

The aim of this study was to follow up two groups of patients with active acromegaly, who underwent to external irradiation and radio-surgery and to value the efficacy of irradiation in the control of the growth of the adenoma, hypersecretion and incidence of adverse events.In 2 groups of patients, (A) of 47 subjects treated with conventional irradiation at a dose of 45 Gy, (B) of 6 subjects irradiated with stereo taxis radiotherapy at a dose of 15-20 Gy, were evaluated GH, IGF1 levels and pituitary function at 2, 5, 10 and 15 years after treatment. A cerebral MRI scan with detailed study of the sellar region was performed every year.Group (A): decrease of GH levels in 9% of patients after 2 years from therapy, 29% after 5 years, 52% after 10 years, 77% after 15 years; normalization of IGF1 levels in 8% of cases after 2 years, 23%, 42% and 61% respectively after 5, 10 and 15 years; hypopituitarism in 57, 78, 85% of patients, respectively after 5, 10 and 15 years. Group (B):normalization of IGF1 levels in 4 of 6 patients after 5 years and in all subjects after 10 and 15 years; progressive decrease of GH levels in all patients and GH normalization in 2 of 6 cases after 10 years; hypopituitarism in 1 patient after 2 years.We confirm the long term efficacy of external Radiotherapy in active acromegaly. Stereo taxis annuls the risks of neurological and neurovascular complications of conventional RT. Although comparison between the two techniques is not statistical significant in our cases we can affirm a faster normalization of IGF1 levels after stereotactic treatment.

Lanreotide Autogel 120 mg (ATG120; Ipsen S.p.A, Milan, Italy) is a high-dose, sustained-release aqueous gel formulation, supplied in a prefilled syringe and given by deep subcutaneous injection. The aim of this study was to compare efficacy and tolerability of ATG120 given every 4-8 weeks with those of octreotide LAR (o-LAR) given every 4 weeks. DESIGN PATIENTS AND INTERVENTION: A phase III multicentre Italian open clinical study of 23 acromegalic patients (15 female, 8 male). All patients had received o-LAR for 6-18 months and, after 3 months wash out, ATG120 was given every 6 weeks for a total of four injections (Period 1). Then the interval between ATG120 injections was adjusted according to three different schemes: every 4, 6 or 8 weeks depending on GH levels (GH2.5 microg/l; 1GHor= 2.5 microg/l; GHor= 1 microg/l, respectively). ATG120 was given for a further two to three doses, with a final assessment (Period 2) at Week 34, 36 or 42.Hormonal (GH and IGF-I) and clinical efficacy and tolerability.ATG120 induced a significant GH decrease from 9.9 +/- 11.3 at baseline (Visit 1) to 3.5 +/- 5.7 at the end of Period 1 (P0.01) and to 3.8 +/- 5.7 microg/l at the final visit (P0.01). IGF-I also decreased from 544 +/- 312 at baseline (Visit 1) to 318 +/- 181 at Period 1 and to 356 +/- 187 microg/l at the final visit (both P0.05 vs. baseline). The frequency of ATG120 administrations was adjusted to every 4 weeks in 12 patients, every 6 weeks in 4 patients and every 8 weeks in 6 patients; 1 patient withdrew before the dose adjustment. Serum GH and IGF-I achieved at the end of Period 1 and Period 2 were similar to those reached with o-LAR. The number of patients who achieved GH2.5 microg/l was comparable between o-LAR (43%) and ATG120 at Period 1 (48%) and at Period 2 (62%). Normal IGF-I levels were recorded in 8 patients during o-LAR (35%), 11 during ATG Period 1 (48%) and 10 at the final visit (43%). Last, 4 patients showed a better response to ATG120 and 2 to o-LAR.Lanreotide Autogel 120 mg is an effective and well-tolerated therapy for acromegaly. In approximately half of patients ATG120 may be administered every 6-8 weeks, instead of every 4 weeks, without lost of efficacy.

Hypertension represents a well-known risk factor for cardiovascular diseases. The pathogenesis of hypertension in acromegaly is commonly viewed as multifactorial, but the possible influence of metabolic disorders on blood pressure (BP) in affected patients is largely unknown.The aim of the present study was to evaluate the impact of glucose metabolism abnormalities on BP values in a series of patients with active acromegaly.An open multicentre prospective study.Sixty-eight patients with active disease, aged 47.5 +/- 11.7 years, have been studied. Thirty-nine had normal glucose tolerance (NGT), 16 impaired glucose tolerance (IGT) and 13 suffered from diabetes mellitus (DM).Mean clinical BP values were calculated as the mean of BP values obtained by sphygmomanometric measurement in three separate occasions and mean 24-h, diurnal and nocturnal systolic (SBP) and diastolic (DBP) values were obtained by 24-h ambulatory blood pressure monitoring (ABPM).Patient's age and the degree of glucose tolerance abnormalities were found to significantly and independently influence BP values. All clinical and ABPM SBP and DBP values significantly increased with age by linear regression (P0.02 for all BP values, 0.30or = Ror = 0.43), and the independent influence of this parameter on BP values was confirmed by mutivariate analysis. Similarly, the independent influence of glucose tolerance abnormalities on BP values was confirmed when introducing age as a covariable in a multivariate analysis, and patients with DM presented significantly higher clinical SBP and 24-h, diurnal and nocturnal SBP and DBP than patients with NGT (P0.02 for clinical SBP, P0.015 for all ABPM values, respectively). In addition, patients with DM showed significantly higher 24-h, diurnal and nocturnal DBP than those with IGT (P0.05 in all cases). In contrast, no significant difference was found between NGT and IGT patients. No significant influence of disease duration, BMI, GH, IGF-I, or fasting and 2-h post glucose load insulinaemia on BP values was observed.Abnormalities of glucose metabolism significantly contribute to increase systolic blood pressure and especially diastolic blood pressure in acromegalic patients. Careful control of blood pressure and of risk factors for developing systemic hypertension, with special reference to glucose tolerance, is mandatory to decrease cardiovascular morbidity and mortality in such patients.

Carney complex is a rare familial multiple syndrome characterised by myxomas, endocrine overactivity, schwannomas, and spotty pigmented lesions on the skin. …

High vascular morbidity and mortality is associated with acromegaly. The aim of the present study was to assess the effects of octreotide therapy on several known cardiovascular risk factors and to correlate them with octreotide-induced hormonal changes. Lipid levels, LDL particle size distribution as evaluated by single vertical spin density gradient ultracentrifugation, apolipoproteins AI and B, lipoprotein (a) [Lp(a)] concentrations and apo(a) phenotypes were evaluated in 20 non-diabetic acromegalic patients (6 M, 14 F), with normal thyroid, adrenal and gonadal function, aged 29-66 years. Normal subjects (20), matched for age, sex and BMI served as control for lipid variables. Acromegalic patients were characterized by lower HDL cholesterol (and apoA-I) and by higher Lp(a) concentrations in comparison to controls. Treatment with octreotide (100 microg t.i.d. for 3 months) led to: an increase in HDL cholesterol (median: + 22%), a decrease in LDL cholesterol (-14%) and a decrease of the Lp(a) levels (all phenotypes) (-28%). The expected decreases of IGF-I levels (median: -48%) and 7-h AUC of GH (-50%), insulin (-40%) and glucagon (-20%) were observed. Only Lp(a) modifications showed a correlation with GH modifications. The study of LDL physical properties showed that acromegalic patients had smaller and/or more dense LDL particles, in comparison with normal controls (relative flotation rate, Rf: 0.40 +/- 0.03 versus 0.42 +/- 0.02 P0q05), an alteration that might contribute to the high vascular risk of acromegalic patients. However, the LDL subfraction distribution remained unmodified during octreotide therapy (Rf 0.39 +/- 0.03). In conclusion, this study shows that in acromegalic patients octreotide treatment is indeed associated with an amelioration of some lipoprotein parameters, i.e. LDL, HDL, and Lp(a) concentrations. However, this treatment has no effect on the small and/or dense LDL particles present in these patients.

As there are few data on the evaluation of the adequacy of levothyroxine (L-T4) therapy in patients with central hypothyroidism (CH), a prospective study was performed to assess the accuracy of various parameters in the follow-up of 37 CH patients. Total and free thyroid hormones, TSH, and a series of clinical and biochemical indexes of peripheral thyroid hormone action have been evaluated off and on L-T4 therapy. Samples were taken before the daily administration of L-T4. In all patients off therapy, clinical hypothyroidism and low levels of free T4 (FT4) were observed, whereas values of FT3, total T4, and total T3 were below the normal range in 73%, 57%, and 19% of cases, respectively. Most of the indexes of thyroid hormone action were significantly modified after L-T4 withdrawal and exhibited significant correlation with free thyroid hormone levels. During L-T4 replacement therapy, 32 patients had circulating levels of FT4 and FT3 and indexes within the normal range with a mean L-T4 daily dose of 1.5 +/- 0.3 microg/kg BW. Despite normal serum FT4, 3 patients had borderline high values of FT3 and a clear elevation of serum-soluble interleukin-2 receptor concentrations, suggesting overtreatment. Low or borderline low FT4/FT3 levels indicated undertreatment in 2 patients. The clinical parameters lack the required specificity for the diagnosis or follow-up of CH patients. The L-T4 daily dose should be established, taking into account the weight, the age, and the presence of other hormone deficiencies or pharmacological treatment of CH patients. In conclusion, our results indicate that the diagnosis of CH is reached at best by measuring TSH and FT4 concentrations. In the evaluation of the adequacy of L-T4 replacement therapy, both FT4 and FT3 serum levels together with some biochemical indexes of thyroid hormone action are all necessary to a more accurate disclosure of over- or undertreated patients.

The p16 gene, which encodes a physiological inhibitor of the cyclin D-CDK4 complex, is now considered as an important tumour-suppressor gene in a variety of tumours. A marked reduction of its expression has been reported to occur without significant genetic alterations in human pituitary adenomas, although rare point mutations of uncertain functional significance have been described. On the other hand, p16 gene silencing due to hypermethylation has been reported in several human primary tumours. The aim of this study was to further investigate the pathogenetic events leading to p16 gene inactivation in pituitary tumours.To screen a european series of human pituitary tumours for p16 gene alterations and possible gene hypermethylation.A representative series of 31 human pituitary tumours-30 macroadenomas, including a MEN-1 non-secreting pituitary adenoma and a non-MEN-1 familial giant GH-secreting adenoma, and one FSH-secreting pituitary carcinoma-was studied.Polymerase chain reaction/single strand conformation polymorphism (PCR-SSCP) analysis was used to screen for p16 gene alterations in all cases. Direct sequencing of PCR-products was obtained by the di-deoxynucleotide method where suspected abnormalities of the PCR-SSCP analysis were observed. In 24 samples, a methylation-specific PCR assay (MSP-PCR) was used to determine p16 gene methylation status.Two sporadic cases of pituitary adenomas had a similar single A to G base substitution leading to an heterozygous Ala140Thr p16 polymorphism, which has not previously been described in such tumours, but is known to be functionally silent. No other p16 abnormality could be suspected from PCR-SSCP analysis in this series. In contrast, the presence of methylated-specific PCR products was observed in 20/24 cases (83.3%).This study confirms that p16 gene mutations are not involved in the pathogenesis of human pituitary tumours, although polymorphisms can be demonstrated, depending on the population considered. In contrast, the high incidence of hypermethylation of the p16 gene suggests that such an alteration occurs early in pituitary tumours, and may play a role in pituitary tumorigenesis.

Hypertension is thought to play an important role in the pathogenesis of acromegalic cardiomyopathy. So far, hypertension has been defined by clinical measurement, with considerable variations reported concerning its prevalence in acromegalics.To determine the mean blood pressure (BP) values and the prevalence of hypertension in patients with active acromegaly according to non-invasive 24-hour ambulatory BP monitoring (ABPM) and to compare the data obtained with those provided by clinical measurement.Forty patients with active acromegaly (22 women, 18 men, mean age 48.6 +/- 12.5 years) were included. Patients were in wash-out for antihypertensive treatment and none had been using any medical treatment for acromegaly for at least 3 months before the study. All were studied as outpatients.Clinical BP values were calculated as the mean of BP values obtained by standard sphygmomanometric measurement in three separate occasions. Mean 24-hour, daytime and night-time BP values were obtained by ABPM.The mean 24-hour BP values were lower than clinical BP values, the difference being significant for both systolic BP (SBP: 131.1 +/- 21.5 versus 136.1 +/- 16.3 mmHg, P0.02) and for diastolic BP (DBP: 74.6 +/- 10.6 versus 88.8 +/- 9.1 mmHg, P0.0001). ABPM values recorded during the daytime were 137.8 +/- 20.9 mmHg for SBP and 78.6 +/- 11.5 mmHg for DBP, the latter being significantly lower than the corresponding clinical BP values (P0.0001). About 60% of the patients considered hypertensive by clinical measurement were found to be normotensive by ABPM, thereby decreasing the prevalence of hypertension in this series from 42.5% to 17.5% according to ABPM (P0.02). In contrast, all patients defined as normotensive by clinical measurement were also normotensive by ABPM.Ambulatory blood-pressure monitoring indicated a lower prevalence of hypertension in acromegalic patients then usually reported, suggesting that the role of hypertension in the pathogenesis of acromegalic cardiomyopathy is commonly overestimated. We propose that ambulatory blood-pressure monitoring should be routinely proposed in acromegalics with high or borderline clinical blood pressure values although it is not useful in patients defined normotensive according to repeated clinical measurement.

The acute GH lowering effects of a single dose of either octreotide (OCT) or cabergoline (CAB), given alone and in combination, were studied in a series of 21 patients with acromegaly.Plasma GH was measured for 8 hours after a single subcutaneous injection of OCT (100 micrograms) and for 48 hours after a single oral dose of CAB (0.5 mg) in all patients. Fourteen patients, who did not suppress GH levels below 5 micrograms/L after either OCT or CAB given alone, also received a combination of both drugs (OCT 100 micrograms s.c. + CAB 0.5 mg p.o. 24 h before OCT).GH levels were acutely suppressed by more than 50% in 15/21 cases after OCT alone and in 5/21 after CAB alone, respectively (P0.01). In the 14 patients who received the combined test, the magnitude of GH suppression was significantly higher than after OCT alone 4, 6 and 8 hours after OCT administration (P0.02). In patients with mixed GH/PRL-secreting tumors, the additive effect of OCT and CAB was observed at each time point.These results suggest that combined therapy with OCT and CAB may be more effective in suppressing GH secretion than either compound given alone, especially in patients with GH/PRL-secreting adenomas.

The effect of increased doses of Somatostatin-14 (3, 10, 30, 100, 300 micrograms/h) on basal release of insulin, pancreatic glucagon and pancreatic polypeptide (PP) was investigated on eight normal volunteers. Levels of Somatostatin-like immunoreactivity (SLI) was determined in order to correlate the increased SLI levels with the degree of islet hormone inhibition (r = 0.9947, p less than 0.01). By increasing the basal levels of SLI by one-third, a significant inhibition (p less than 0.01) of insulin, glucagon, and PP was noted (78.5, 78.6, 75.2%, respectively, on basal levels). The maximal effect was obtained with 300 micrograms/h for insulin, with 30 micrograms/h for glucagon and 100 micrograms/h for PP. In evaluating the relative inhibitory potency of somatostatin, expressed as ED50, the theoretic potency of somatostatin on each peptide had similar values, ranging from 30 to 10 micrograms/h. The present data show that a minimal peripheric increase in SLI is able to regulate basal islet pancreatic hormones.

A prospective randomized study was carried out to evaluate the nutritional and clinical results of two reconstructive procedures after total gastrectomy for gastric cancer: Longmire-Mouchet (LM) operation with loop interposition and maintained duodenal transit and Roux-en-Y (RY) reconstruction with duodenal exclusion. 22 patients, 11 with LM reconstruction and 11 with RY reconstruction were studied pre-and postoperatively. The average follow-up was of 30 +/- 8 months. The clinical results were shown to be substantially similar to the two groups. No patients complained of heartburn or dysphagia. At esophagoscopy no signs of esophagitis were detected in both groups. The two time course curves of body weight variation did not show statistically significant differences even though in RY patients the body weight has reverted more rapidly to basal values.

Acromegaly is caused by a GH-secreting pituitary adenoma, associated with many comorbidities and increased risk of mortality. Surgery is the first-line therapy. Success of therapy is measured by symptomatic improvement, preservation of pituitary function and biochemical control. Trans-sphenoidal surgery (TSS), endoscopic or microscopic, is the preferred treatment. To evaluate surgery effectiveness and individuate the technique associated with a higher remission rate, patients undergoing TSS were retrospectively selected.Thirty-seven consecutive patients underwent surgery between 1996 and 2006. Tumors were classified into macroadenomas or microadenomas and into intrasellar, extrasellar and extrasellar with cavernous sinus invasion. Surgery was performed in 22 patients with endoscopic technique, in 15 patients with microsurgical approach. The hormonal assays were performed 6 months and yearly after surgery for an average of 5 years.Ten patients were affected by microadenoma, 27 by macroadenoma. In microadenomas remission rate was independent of the used technique. Within macroadenomas, remission percentage in endoscopic approach (68.75%) was significantly higher than in microscopic approach (18.18%) (P=0.018). Postsurgical biochemical remission was calculated combining the surgical technique and tumor extension: the endoscopic approach was associated with a significantly higher remission rate in extrasellar than both in intrasellar and extrasellar with cavernous sinus invasion. In the latter group, any technique had not reached biochemical remission.TSS is able to induce a long-term remission of acromegaly, with low risk of recurrence and complications. Endoscopic approach is more suitable than microscopic technique in macroadenomas and adenomas with suprasellar extension.

We evaluated the sensitivity of 111In-Octreotide scintigraphy in the diagnosis of pancreatic insulinoma in a selected number of patients. In addition, we compared the results of scintigraphy with those of other conventional diagnostic techniques. Seven patients with surgically confirmed insulinoma (1.5 cm in diameter) of the pancreas were studied. Before surgery, patients underwent arteriography with Ca-gluconate, CT scan, and 111In-Octreotide scintigraphy. 111In-Octreotide scintigraphy showed a higher diagnostic specificity (85%) than selective arteriography (83%) or CT scan (57%). We conclude that 111In-Octreotide scintigraphy should always be performed before surgery in cases of pancreatic insulinoma and that a SPECT acquisition should be performed both 6 and 24 hours post-injection in order to increase the diagnostic sensitivity of the test.

CONTEXT: Familial pituitary adenomas occur rarely in the absence of multiple endocrine neoplasia type 1 (MEN1) and Carney complex (CNC). OBJECTIVE: Our objective was to characterize the clinical and genealogical features of non-MEN1/CNC familial isolated pituitary adenomas (FIPA). DESIGN AND SETTING: We conducted a retrospective study of clinical and genealogical characteristics of FIPA cases and performed a comparison with a sporadic population at 22 university hospitals in Belgium, Italy, France, and The Netherlands. RESULTS: Sixty-four FIPA families including 138 affected individuals were identified [55 prolactinomas, 47 somatotropinomas, 28 nonsecreting adenomas (NS), and eight ACTH-secreting tumors]. Cases were MEN1/PRKAR1A-mutation negative. First-degree relationships predominated (75.6%) among affected individuals. A single tumor phenotype occurred in 30 families (homogeneous), and heterogeneous phenotypes occurred in 34 families. FIPA cases were younger at diagnosis than sporadic cases (P = 0.015); tumors were diagnosed earlier in the first vs. the second generation of multigenerational families. Macroadenomas were more frequent in heterogeneous vs. homogeneous FIPA families (P = 0.036). Prolactinomas from heterogeneous families were larger and had more frequent suprasellar extension (P = 0.004) than sporadic cases. Somatotropinomas occurred as isolated familial somatotropinoma cases and within heterogeneous FIPA families; isolated familial somatotropinoma cases represented 18% of FIPA cases and were younger at diagnosis than patients with sporadic somatotropinomas. Familial NS cases were younger at diagnosis (P = 0.03) and had more frequently invasive tumors (P = 0.024) than sporadic cases. CONCLUSIONS: Homogeneous and heterogeneous expression of prolactinomas, somatotropinomas, NS, and Cushing's disease can occur within families in the absence of MEN1/CNC. FIPA and sporadic cases have differing clinical characteristics. FIPA may represent a novel endocrine neoplasia classification that requires further genetic characterization

Neuroendocrine tumors may occur in the setting of multiple endocrine neoplasia type 1 (MEN1) syndrome. Among these, a probably underestimated prevalence of well differentiated neuroendocrine thymic carcinoma (carcinoid), a neoplasm characterized by very aggressive behavior, has been described. We report characterization of the seven Italian cases in which this association occurred among a series of 221 MEN1 patients (41 sporadic and 180 familial cases; prevalence, 3.1%). All of the patients were male, and six of seven (85%) were heavy smokers. No associated hormonal hypersecretion was detected. The first diagnosis was between the second and fifth decades. Familial clusters were present in three of seven (42.8%). No genotype-phenotype correlation was found. All seven cases were associated with hyperparathyroidism. In one patient, prophylactic thymectomy revealed a small nodular lesion suggestive of a thymic carcinoid, providing evidence that preventive thymectomy might prevent additional growth of an occult thymic carcinoid. These findings confirm that thymic carcinoids are associated with a very high lethality, with a near-total prevalence in smoker males. Therefore, prophylactic thymectomy should be considered at neck surgery for primary hyperparathyroidism in MEN1 male patients, especially for smokers, and, due to the frequent familial clusters distribution of this pathology, in subjects with affected relatives presenting this feature. Thus, we recommend screening every patient affected with a neuroendocrine thymic neoplasm for MEN1 syndrome.

Recently, a new slow-release (SR) formulation of lanreotide (LAN) comprising 60 mg of the drug incorporated in microspheres of biodegradable polymers (SR-LAN 60) has become available. The aim of our study was to assess the effectiveness of SR-LAN 60, administered every 21 to 28 days, as well as its tolerability in the long-term treatment of acromegalic patients treated with SR-LAN 30. Twenty patients with acromegaly (10 males and 10 females) were enrolled in this open study. Thirteen patients had undergone surgery, but with incomplete resection of the pituitary tumor. All patients, treated with intramuscular (IM) SR-LAN 30 injections every 10 days for 12 to 24 months, started SR-LAN 60 (Ipsen-Beaufour, Milan, Italy) administration 10 days after the last injection of SR-LAN 30. Growth hormone (GH) levels were determined on the day of the first injection of SR-LAN 60, and 10, 20, and 30 days after. According to the GH levels reached on day 30, patients received SR-LAN 60 every 28 days if GH levels were below 2.5 microg/L (group A) and every 21 days if GH levels were above 2.5 microg/L (group B). In group A, after the 8th month, SR-LAN 60 treatment resulted in well-controlled GH levels in 9 of 10 patients in comparison to SR-LAN 30 treatment every 10 days (6 of 10 patients). Normal age-adjusted insulin-like growth factor-I (IGF-I) levels were achieved in 4 of 10 patients, as in treatment with SR-LAN 30. In group B, SR-LAN 60 treatment resulted in well-controlled GH levels in 4 of 10 patients, as in treatment with SR-LAN 30 every 10 days. Normal age-adjusted IGF-I levels were achieved in 3 of 10 patients after SR-LAN 60 in comparison to SR-LAN 30 treatment every 10 days (1 of 10 patients). During SR-LAN 60 therapy, an improvement was also observed in signs and symptoms of active acromegaly and no relevant side effects were detected. In conclusion, this study shows that SR-LAN 60 treatment is able to induce a good control of circulating GH and IGF-I levels in most acromegalic patients. The first injections of SR-LAN 60 are very helpful in predicting the optimal long-term injection frequency. Patients on SR-LAN 30 can be safely and effectively shifted to SR-LAN 60.

The effect of bombesin on insulin, pancreatic glucagon, and gut glucagon was investigated in eight healthy volunteers and two pancreatectomized patients. Bombesin, infused iv at the constant rate of 5 ng kg-1 min-1, produced a sharp and statistically significant rise in the plasma insulin concentration. The peak was reached at 5 min (26 +/- 2.17 microU/ml; P less than 0.005 vs. basal values), followed by a prolonged and statistically significant (P less than 0.05) decrease in blood glucose. Pancreatic glucagon rapidly rose to a maximal value of 80.5 +/- 7.6 pmol/liter (P less than 0.005 vs. basal values). In contrast with the prompt increase in insulin and glucagon plasma levels, the peak in gut glucagon concentration (55.8 +/- 4.6 pmol/liter; P less than 0.005 vs. basal values) was reached 30 min after bombesin infusion was discontinued. In the two pancreatectomized patients, bombesin induced an increase in gut glucagon concentrations only. The results presented indicate that bombesin acts directly on the A and B cells of the pancreas, influencing glucose homeostasis; however, more complex mechanisms seem to be involved in gut glucagon secretion.