Pancreatic islet-cell neoplasia, with secretion of a parathormone-like substance and hypercalcemia

In a 47-year-old woman with a pancreatic mass associated with hypercalcemia and mental confusion, medical measures failed to restore her serum calcium level to normal. To do so, radical resection of a locally invasive vascular neoplasm arising from the body and tail of the pancreas was necessary. The neoplasm was a pancreatic islet-cell tumour. Serum parathormone assays demonstrated abnormally high secretion of a parathormone-like substance. Ectopic secretion of such substances from islet-cell tumours should be considered in association with refractory metabolic disturbances. In view of the often indolent clinical course of islet-cell tumours and the potential for life-threatening hormonal effects, biopsy confirmation of adenocarcinoma should be obtained before resorting to palliative surgical management of pancreatic neoplasms.

Fine-needle aspiration cytology in pancreatic endocrine tumors

Pancreatic endocrine tumors (PETs) are relatively uncommon neoplasms. Although their histologic patterns have been widely studied, their cytologic features as they appear in fine-needle aspiration (FNA) specimens have rarely been reported. In this study, aspirates of seven PETs, four primary and three metastatic lesions (two to liver and one to bone), are described. The tumors occurred in seven men ranging in age from 37 to 72 yr. Six tumors presented as nonfunctioning masses and one produced Zollinger-Ellison syndrome. Three were located in the head of the pancreas and four in the body and tail. The pancreatic and liver aspirations were performed under computed tomographic guidance and the bone lesion, under fluoroscopy. The aspiration specimens were hypercellular. The tumor cells occurred singly and in small clusters. In three cases, there was a tendency toward acinar formations. In two cases, there were prominent, thin-walled, branching blood vessels with tumor cells attached to the vascular walls. The cells were round or polygonal with a moderate amount of finely granular, well-defined cytoplasm. The nuclei were eccentrically located and round-to-oval--with one or two small nucleoli and finely granular, evenly-dispersed chromatin. The diagnosis was confirmed by immunocytochemistry (two cases) and electron microscopy (four cases) of the aspirated material and histology sections of the resected tumors (two cases). The results of this study demonstrate that FNA is a useful method to establish the diagnosis of PETs.

Glucose turnover in insulinoma--a case report

To define glucose flux in a state of chronic endogenous insulin excess, a patient with an insulinoma was studied. Plasma glucose, insulin (IRI), glucagon (IRG) and glucose turnover ([3-3H]glucose infusion) were measured before and after insulinoma resection in the postabsorptive state (PA), during a glucose infusion adjusted to attain euglycemia (before insulinoma resection only) and following an intravenous glucagon bolus (1 mg). Before insulinoma resection, plasma glucose was 55 mg/dl, glucose production (Ra) and disappearance (Rd) were equal (1.6 mg/kg/min) and glucose clearance was elevated (2.8 ml/kg/min) in PA. When glycemia was raised with a glucose infusion to 77 mg/dl, Rd did not change; in contrast Ra dropped to zero. Plasma IRI and IRG concentrations were 0.7 ng/ml and 110 pg/ml respectively before glucose infusion and remained constant throughout. After resection of the insulinoma, glycemia in PA was 103 mg/dl, Ra and Rd were increased slightly to 1.9 mg/kg/min while the metabolic clearance of glucose was decreased by 25% (2.1 ml/kg/min). Glucagon stimulation pre- and postinsulinoma resection resulted in significant increases in glycemia and IRI. We conclude that hypoglycemia with insulinoma is a consequence of decreased glucose production and increased glucose clearance. Hepatic sensitivity to small increments in glycemia is markedly enhanced so as to fully suppress endogenous glucose production at euglycemic levels in the absence of any change in IRI and IRG. The mechanisms controlling hepatic Ra in insulinoma appear different from normal.

Cushing's syndrome due to ectopic proopiomelanocortin gene expression by islet cell carcinoma of the pancreas

Expression of proopiomelanocortin (POMC) was studied in a male patient with Cushing's syndrome and ectopic production of ACTH by a pancreatic carcinoma. Plasma ACTH levels (greater than 200 pg/ml) were elevated, and elevated serum cortisol and urinary free cortisol were partially suppressed to 25% of basal levels by high-dose dexamethasone. Petrosal and jugular vein sampling did not yield a gradient of ACTH. Immunohistochemical staining of tumor tissue removed at pancreatectomy was positive for ACTH and beta endorphin, and negative for corticotropin-releasing factor (CRF). Tumor cells cultured in vitro secreted ACTH and beta-endorphin, which comigrated with their respective radiolabeled standards on gel chromatography. Hydrocortisone suppressed in vitro ACTH secretion and CRF (100 nM) stimulated ACTH by 50% during 72 hours of incubation. Agarose gel electrophoresis of poly-(A) mRNA extracts of tumor tissue followed by hybridization with 32P-cDNA for POMC revealed 2 distinct RNA species. The major RNA species (about 1.0 kb) was smaller than authentic pituitary POMC mRNA (about 1.1 kb); a larger precursor band also was visualized, suggesting either processing or degradation of tumor-POMC mRNA. Cytoplasmic dot blot hybridization of tumor mRNA with POMC cDNA yielded a positive signal with increasing amounts of RNA blotted. Immunohistochemistry and radioimmunoassay (RIA) of ACTH, in vitro regulation of ACTH secretion, and expression of POMC mRNA species by this tumor document expression of the human POMC gene by an islet carcinoma associated with Cushing's syndrome.

Multipotential phenotypic expression of genes encoding peptide hormones in rat insulinoma cell lines

The developmental origin of the four phenotypically distinct hormone-producing islet cells (insulin, glucagon, somatostatin, pancreatic polypeptide) is unclear. To investigate the potential for phenotypic differentiation of islet cells, we prepared several clonal cell lines from a radiation-induced rat islet tumor and analyzed them for insulin, glucagon, and somatostatin gene expression by cDNA hybridization, immunocytochemistry, and radioimmunoassay. We found expression of all three genes in the tumor and in the parental cell line and mixed variable phenotypes in the clonal lines derived from the parental line. We also observed the ectopic expression of the angiotensinogen gene in the tumor and the cell lines. The relative levels of hormonal gene expression differed among the cell lines but remained fixed during continuous passage. The three islet hormone mRNAs were larger compared to the pancreas owing to longer poly(A) tracts. These observations indicate that neoplastic islet cells retain the potential to differentiate into hormone-specific cellular phenotypes and may mimic developmental pathways of the pancreatic islets.

ACTH-producing apudoma metastatic to the liver

A young man presented with combative psychosis and elevated levels of plasma adrenocorticotropic hormone (ACTH). A solitary vascular pancreatic mass and diffuse vascular hepatic nodules were demonstrated on selective splenic and hepatic arteriograms. These classic angiographic findings are used to emphasize the role of angiography in initial radiographic evaluation and to summarize the angiographic appearance of functioning pancreatic adenomas. Even though this is an aggressive tumor, early diagnosis and intensive treatment may allow prolonged remission, if not cure.

Effects of cytotoxic drugs and inhibitors of insulin secretion on a serially transplantable rat insulinoma and cultured rat insulinoma cells

The effects of cytotoxic drugs and inhibitors of insulin secretion were examined in vivo in rats with a radiation-induced transplantable insulinoma, and in vitro using cultured rat insulinoma cells and the derived RINm5F insulin-secreting cell line. Administration of diazoxide to insulinoma-bearing rats resulted in a transient decrease of plasma insulin with a temporary rise of glucose concentrations. Mannoheptulose and somatostatin failed to affect the marked hyperinsulinaemia and hypoglycaemia. Streptozotocin produced a rapid and sustained decrease of insulin concentrations in insulinoma-bearing rats, accompanied by a progressive elevation of plasma glucose. Administration of alloxan failed to affect circulating insulin or glucose concentrations. In vitro, streptozotocin and alloxan exerted approximately equipotent time-dependent and concentration-dependent cytotoxic effects on insulinoma cells and RINm5F cells as established by cell staining with trypan blue. The cytotoxic actions of both drugs were decreased by agents believed to scavenge free radicals or to act as inhibitors of poly(ADP-ribose) synthetase. The results suggest that the cytotoxic actions of streptozotocin and alloxan on rat insulinoma cells and RINm5F cells are mediated by the generation of hydroxyl free radicals and DNA strand breaks. The ineffectiveness of alloxan in insulinoma-bearing rats probably reflects the high rate of decomposition of the drug in vivo.

Free amino acid levels in muscle and liver of a patient with glucagonoma syndrome

This study set out to measure the amino acid concentrations in the femoral artery, femoral vein, hepatic vein, muscular and hepatic tissue, and urine of a patient with the glucagonoma syndrome. The total plasma amino acid concentration was severely reduced on admission (737 mumol/L, 26% of normal), with only a slight increase during intravenous administration of 200 g of amino acids per day. The total intracellular amino acid levels in the muscle were 86%, and those of the liver were 47% of the normal range. Only 0.62% of the amino acids administered were found in the urine. Arteriovenous amino acid concentration differences across the muscle and splanchnic tissue indicated the release of amino acids (mainly glutamine, glycine, and alanine) from the muscle and the absorption of amino acids by the splanchnic bed. This study shows that the infusion of a high amount of amino acids cannot increase the subnormal plasma AA levels of patients with the glucagonoma syndrome. The low total plasma AA levels are paralleled by decreased intracellular free amino acid levels in the muscle and liver.

Effect of a transplantable insulinoma upon serotonin concentrations in the intestine of the rat

Rapid growth of a transplantable insulinoma in rats over a 14 day period results in hyperphagia together with a selective increase in the weight and enteroglucagon (GLI) concentration of the small intestine. Measurement of serotonin concentrations by an HPLC/fluorometric method demonstrated an increase in blood (91%; p less than 0.05) and in extracts of colon (22%; p less than 0.05) but no change in extracts of the small intestine and caecum. The data support the hypothesis that the rise in enteroglucagon is related directly to the growth of the small intestine and is not a non-specific effect of hyperphagia.

Glucose induces insulin release and a rise in cytosolic calcium concentration in a transplantable rat insulinoma

An important role for calcium in the cellular events leading to insulin secretion is supported by many studies. However, simultaneous measurements of changes in intracellular free Ca2+ concentrations [( Ca2+]i) and insulin release in response to secretagogues have not been performed. Using cells isolated from a glucose-responsive insulinoma, changes in [Ca2+]i were measured with the fluorescent calcium probe quin2. With the nutrient secretagogues glucose (30 mM) and D,L-glyceraldehyde (GA; 20 mM), [Ca2+]i increased slowly, reaching a peak approximately 15 min after addition of the stimulus, while KCl (25 mM) and carbachol (2 mM) led to a rapid but transient increase in [Ca2+]i. Glucose increased [Ca2+]i from 104 +/- 6 (mean +/- SEM) to 248 +/- 31 mM (n = 13), and GA caused a rise in [Ca2+]i from 96 +/- 6 to 280 +/- 39 nM (n = 4). KCl and carbachol caused a rise from 107 +/- 6 to 184 +/- 5 nM and from 98 +/- 5 to 157 +/- 5 nM, respectively (n = 5 each). When insulin release was measured simultaneously with changes in [Ca2+]i and compared to unstimulated cells, the following results were obtained. During the first 5 min of stimulation, high glucose caused a 90 +/- 12% increase in insulin release and a 72 +/- 11% rise in [Ca2+]i (n = 5). GA evoked a 122 +/- 30% increase in insulin secretion, with a 82 +/- 17% rise in [Ca2+]i (n = 3). Both KCl and carbachol caused a 58 +/- 9% increase in insulin release, with 7 +/- 4% and 50 +/- 2% rises in [Ca2+]i, respectively (n = 4 each). Insulin release was also measured in a perifusion system. It was shown that glucose (30 mM), GA (20 mM), and alpha-ketoisocaproate (30 mM) caused a biphasic release of insulin, while KCl (25 mM) and carbachol (2 mM) caused a monophasic release. The results show that [Ca2+]i increases during the stimulation of insulin secretion when measured simultaneously on the same beta-cells. However, while these changes coincide, a simple direct quantitative relationship between insulin release and the rise in [Ca2+]i could not be demonstrated.

3-O-methyl-D-glucose transport in tumoral insulin-producing cells

Tumoral insulin-producing cells of the RINm5F line were exposed at different temperatures, and for various lengths of time to increasing concentrations of 3-O-methyl-D-[U-14C]glucose. The uptake of the hexose represented a temperature-sensitive and saturable process, so that no rapid equilibration of hexose concentrations across the plasma membrane was reached, especially at low temperature and/or high concentrations of 3-O-methyl-D-glucose. The uptake of 3-O-methyl-D-[U-14C]glucose was not affected by a prior loading of the cells with the unlabeled hexose and its release from prelabeled cells was observed in the absence of any concentration gradient across the plasma membrane. The uptake of D-[U-14C]glucose and utilization of D-[5-3H]glucose was inhibited by 3-O-methyl-D-glucose, which failed, however, to affect D-[U-14C]glucose oxidation. At variance with the situation found in normal insulin-producing cells, the transport of D-glucose into the tumoral cells may thus play a regulatory role in its metabolism.

Glucose transport by radiation-induced insulinoma and clonal pancreatic beta-cells

Sugar uptake was measured in dispersed cells prepared from radiation-induced insulinomas transplantable in NEDH rats and in three clonal beta-cell lines maintained in continuous culture (RIN m5F, RIN 1046, HIT). Uptake of D-glucose and 3-O-methyl-D-glucose by insulinoma cells was rapid so that the intracellular concentration of D-hexoses approximated the concentration in the incubation medium by 15-30 s. L-Glucose was taken up only slowly. 3-O-methyl-D-glucose uptake by RIN m5F, RIN 1046, and HIT cells was slow; with 1 mM 3-O-methylglucose in the medium, equilibrium was attained at 20 min, but with 10 mM 3-O-methylglucose, equilibrium was not attained even at 20 min. In HIT cells incubated with D-glucose for 30 min, the intracellular concentration of glucose was less than the medium glucose concentration, indicating glucose transport is a nonequilibrium reaction in this cell line. These data indicate that radiation-induced insulinoma cells retain the capacity of normal beta-cells to transport sugar at high rates. RIN m5F, RIN 1046, and HIT cells transport sugar slowly, however, and thus differ from normal beta-cells. In RIN m5F, RIN 1046, and HIT cells, unlike in normal beta-cells, glucose transport may be the site regulating glucose metabolism.

D-glucose transport and concentration in tumoral insulin-producing cells

The uptake of D-[U-14C]glucose and D-[5-3H]glucose by tumoral insulin-producing cells of the RINm5F line was measured over 3-30 min of incubation at 7-37 degrees C. The apparent distribution space of the hexose ranged from values as low as the L-[1-14C]glucose space to values 10 times higher than the 3H2O space. Although a major fraction of the radioactivity recovered in the cellular pellet corresponded to the metabolites of D-glucose, the results suggested that the transport of D-glucose into the tumoral cells represents a saturable and temperature-dependent process. When D-glucose was measured by an enzymic procedure in cells incubated for 30 min at 37 degrees C in the presence of 50.0 mM D-glucose, the apparent distribution space of the hexose remained lower than the intracellular water space. These results indicate that the RINm5F cells have lost an essential attribute of the glucose-sensing device in normal insulin-producing cells, namely the ability to ensure the equilibration of D-glucose concentrations across the plasma membrane.

Cloned cell lines from a transplantable islet cell tumor are heterogeneous and express cholecystokinin in addition to islet hormones

A liver metastasis (MSL) with a remarkable in vitro proliferation potential has been identified in an NEDH rat carrying a transplantable x-ray-induced islet cell tumor. Two insulin-secreting cell lines, MSL-G and MSL-H, with doubling times of 3-5 d were established by repeated limiting dilution cloning. In vivo inoculation of MSL-G cells induced severe hypoglycemia caused by a small but highly heterogeneous tumor as revealed by immunocytochemistry. Whereas most cells stained for the islet hormones, insulin, glucagon, and somatostatin, clustered cells were discovered to contain cholecystokinin (CCK). Additional in vitro-limiting dilution cloning, followed by immunocytochemical characterization, clearly demonstrated the capacity of single cell clones to simultaneously express the same four hormones. Radioimmunoassays with a panel of site-specific antisera of culture supernatants and purified cell extracts showed the MSL-G2 cells to produce, store, and secrete readily detectable amounts of processed and unprocessed CCK. Gastrin was not detected while coexpression of glucagon and CCK were demonstrated. Mutant clones selected for resistance to 6-thioguanine (frequency, 2 X 10(-7] and checked for HAT (hypoxanthine, aminopterin, thymidine) sensitivity retained the capacity for multi-hormone expression. We propose that the MSL tumor contains pluripotent endocrine stem cells. The MSL tumor and the MSL-G2 cells in particular will allow studies of not only CCK biosynthesis and processing but also of mechanisms involved in tumor and islet cell differentiation.

Effects of transplantation and resection of a radiation-induced rat insulinoma on glucose homeostasis and the endocrine pancreas

Twenty-one days after s.c. subscapular transplantation of a radiation-induced insulinoma, male NEDH rats exhibited hyperinsulinaemia and hypoglycaemia. These features were associated with islet atrophy, degenerative changes in pancreatic A and B cells, and decreases in the pancreatic contents of insulin, glucagon and somatostatin. The immunoreactive glucagon and somatostatin contents of extrapancreatic tissues of insulinoma-bearing rats were unchanged. Surgical resection of the tumour resulted in an immediate fall of plasma insulin, attaining concentrations similar to those of anaesthetised control rats by 10 min. The estimated half-life of insulin was 3.5 min. Hypoglycaemia persisted until 60 min after resection, followed by hyperglycaemia of 1-2 days duration. Glucose tolerance was impaired 1 day after tumour resection despite the coexistence of raised insulin concentrations. Evidence for abnormal pancreatic B cell function was gained by injection of arginine which failed to evoke a plasma insulin response in the resected rats. Two days after resection, plasma glucose and insulin concentrations were similar to those of control rats. Plasma glucose and insulin responses to glucose and arginine were suggestive of tumour recurrence by 12 days. A single large encapsulated tumour was eventually observed in each rat, with resection giving a 17-56 day prolongation of life.

P19, a hormonally regulated phosphoprotein of peptide hormone-producing cells: secretagogue-induced phosphorylation in AtT-20 mouse pituitary tumor cells and in rat and hamster insulinoma cells

P19, a group of 19,000 mol wt cytosolic proteins, with apparent isoelectric points of pI 5.9, pI 5.7, and pI 5.4, respectively, was identified in three peptide hormone-producing cell types: AtT20 mouse pituitary tumor cells, RIN-1122 rat insulinoma cells, and hamster insulinoma cells. Secretagogue-dependent phosphorylation of P19 was analyzed in 32P-labeled cells by two-dimensional electrophoresis and autoradiography. The results were quantitated by computer-assisted densitometry. Cellular levels of cAMP and hormone release were measured in parallel incubations. In addition to stimulating ACTH release, CRF raised the cellular level of cAMP and increased the 32P labeling of all three 19,000 mol wt proteins in AtT20 cells. Other agents known to act through cAMP, which included isoproterenol, forskolin, and 8-bromo-cAMP, mimicked the effect of CRF on both ACTH release and phosphorylation of P19. 12-O-Tetra-decanoylphorbol-13-acetate, a tumor-promoting phorbol ester, also stimulated both ACTH release and phosphorylation of P19. In contrast, although 40 mM K+ promoted ACTH release, it did not affect the phosphorylation of P19. Analogous findings were observed in insulinoma cells. Glucagon stimulated insulin release, increased cellular cAMP and promoted phosphorylation of P19 in RIN 1122 cells. 12-O-Tetradecanoylphorbol-13-acetate also enhanced insulin release and the phosphorylation of P19 in these cells. The results obtained with hamster insulinoma cells closely resembled the observations in RIN-1122 cells. In conclusion, P19, an apparently homologous set of cytosolic proteins, undergoes phosphorylation in three peptide hormone-producing cells in response to two groups of secretagogues, the effect of which is probably mediated, in one case, by cAMP-dependent protein kinase and, in the other, by protein kinase C. The data suggest the possibility that P19 participates in a secretory pathway activated by these two effector systems.

Reduction of pituitary size by the somatostatin analogue SMS 201-995 in a patient with an islet cell tumour secreting growth hormone releasing factor

Acromegaly is rarely caused by the ectopic secretion of growth hormone releasing factor (GRF) from peripheral neuroendocrine tumours. We evaluated the ability of a recently developed somatostatin analogue (SMS 201-995, Sandoz) to reduce hormone levels and pituitary size in a young woman with acromegaly and Zollinger-Ellison syndrome secondary to a metastatic pancreatic islet cell tumour secreting GRF and gastrin. Gastrin, GRF, and growth hormone (GH) levels declined dramatically following the initiation of therapy with the analogue by continuous iv infusion. Although intermittent sc therapy was not effective in suppressing hormone levels, continuous sc infusion of SMS 201-995 has provided good control of both GRF and GH levels for nine months. Moreover, treatment with SMS 201-995 was associated with a substantial reduction in pituitary enlargement and an improvement in her gastric symptoms. Continuous sc infusion of SMS 201-995 may be useful in treating enlarged pituitaries resistant to other modes of therapy.

Thyrotropin-releasing hormone and insulin in chemically induced pancreatic islet cell tumors in rats

Thyrotropin-releasing hormone (TRH) and insulin were measured by radioimmunoassay in acetic-acid extracts of 19 pancreatic islet cell tumors induced by streptozotocin and nicotinamide in rats. In addition, gel filtration properties of TRH-immunoreactivity and immunoreactive insulin (IRI) were examined in 5 and 14 tumors, respectively. TRH was demonstrated in 10 of 19 tumors, with a mean of 166 +/- 47 (SEM) pg/mg wet weight, whereas the concentration was less than 3 pg/mg wet weight in the other tumors. In contrast, all tumors contained IRI, with a mean of 11.0 +/- 1.6 micrograms/mg wet weight. Ten tumors in which TRH was demonstrated contained more IRI than those in which TRH was not detected (13.1 +/- 1.8 vs 6.5 +/- 1.7 micrograms/mg wet weight, P less than 0.02). After gel filtration, all TRH immunoreactivity was eluted at the same place as synthetic TRH in the 5 tumors. In addition, gel filtration elutes showed essentially the same pattern of IRI in the 14 tumors, with 3 peaks. The predominant IRI peak comigrated with marker insulin (95.7 +/- 0.8%), another prominent peak occurred coincident with proinsulin standard (3.3 +/- 0.5%), a third peak was present in the void volume (0.28 +/- 0.04%). These distributions of IRI were similar to those in extracts of normal pancreases. The present studies demonstrate TRH immunoreactivity in pancreatic islet cell tumors induced by streptozotocin and nicotinamide in rats. Chemically induced insulinomas can serve as a model for insulin storage which is analogous to islet B cells.

Secretion of pancreatic polypeptide in patients with pancreatic endocrine tumors

Pancreatic polypeptide is often secreted by pancreatic endocrine tumors and is considered a marker for such tumors. To investigate the diagnostic value of this marker, we studied 323 patients with proved pancreatic endocrine tumors. We found plasma concentrations of pancreatic polypeptide to be elevated (more than 300 pmol per liter) in 144 patients (diagnostic sensitivity, 45 percent). However, plasma levels of pancreatic polypeptide can also be elevated in the absence of a pancreatic tumor. To ascertain whether the administration of atropine could distinguish between normal and tumor-associated polypeptide secretion, we studied 30 patients with pancreatic tumors and high plasma levels of pancreatic polypeptide, 18 patients without tumors who had elevated levels of pancreatic polypeptide, and eight normal controls. Polypeptide levels in the 18 patients without tumors were substantially lower than in the 30 patients with tumors. Atropine (1 mg intramuscularly) did not suppress polypeptide levels in patients with tumors, but did suppress plasma levels by more than 50 percent in all subjects without tumors. Thus, although its diagnostic sensitivity is low, pancreatic polypeptide appears to be a useful adjunctive marker of many pancreatic endocrine tumors, and the atropine suppression test can be used to distinguish normal from tumor-related secretion of the polypeptide. Identification of the type of pancreatic endocrine tumor still requires measurement of the hormone that is specific for the tumor.

Morphology of a GHRH producing pancreatic islet cell tumour causing acromegaly

A 54 year old woman suffered from acromegaly due to a pancreatic islet cell tumour producing GHRH. The tumour was demonstrated on CT scan. The diagnosis was established from elevated plasma levels of GHRH, GH and prolactin, and by the lack of signs of a pituitary adenoma in trans-sphenoidal surgery. Acromegaly was cured by tumour removal. Light microscopically, the tumour showed a medullary and microlobular pattern. The cells were large and often cuspidal. Small granules were found in semi-thin sections. Small aggregations of amyloid fibres were seen, mostly around capillaries. Immunocytochemistry revealed GHRH, NSE, neurotensin, serotonin, VIP and PP. S 100 was positive only in nerve fibres. Staining for GH, ACTH, calcitonin, alpha-HCG, beta-HCG, insulin, glucagon, gastrin, substance P, bombesin and somatostatin was negative. Ultrastructure showed oval partly lobulated nuclei with small nucleoli, moderate amounts of rough endoplasmic reticulum, many free ribosomes, some large Golgi fields and small numbers of secretory granules measuring 150 nm or, in a few cells, 650 nm. Only 4 other cases of pancreatic endocrine tumours causing acromegaly by ectopic GHRH secretion are described in the literature and these were similar to our case in many respects.

[Carcinoid of ectopic pancreas tissue--islet cell tumor]

A case of islet cell tumor--carcinoid of the ectopic pancreas is reported. The patient had been operated six times because of recurrent abdominal tumor mass and intermittent hypoglycemic coma. The first five operations were done with the diagnosis of mesotheliosarcoma by pathology. The last operation was done in our hospital with the final diagnosis of carcinoid--islet cell tumor. In addition to the light microscopic view, several diagnostic features were observed as follows: Under electron microscopy, membrane bound secretive granules were present in the tumor cytoplasm. Neither brush-like microvilli nor lumen formation of the mesothelioma were found. By immunohistochemistry, positive granules to immunoperoxidase stain of insulin were observed in some tumor cytoplasm. By laboratory test, levels of blood 5-hydroxytryptamine and urinary 5-hydroxyindolacetic acid were elevated. Sometimes it is difficult to differentiate carcinoid from islet cell tumor only by morphology, because both are derived from the same origin during the embryonic development which is probably related to the endocrine system from the embryonic foregut. The latter arises from the neuro-ectoderm and belongs to APUD system.

Long-term plasma glucose normalization in experimental diabetic rats with macroencapsulated implants of benign human insulinomas

Permselective tubular membranes (1 mm i.d.) were filled with fragments of nine freshly resected human insulinomas, closed at both ends, and implanted in the peritoneal cavity of 30 streptozocin-induced diabetic rats. In 14 animals, nonfasting plasma glucose (PG) and insulin levels were normalized by these immunoprotected transplants for up to 1 yr (PG from 520 +/- 12 to 142 +/- 3 mg/100 ml; insulin from 6 +/- 0.5 to 44 +/- 3 microU/ml). These animals showed the same weight gain after 12 mo of observation as 20 controls. The remaining 16 animals showed an incomplete or transient correction of their diabetes and survived 4-6 mo, versus less than 8 wk in untreated animals. Removal of the membrane-encapsulated insulin-secreting tissue from 8 successfully treated rats led to hyperglycemia and death within 10 days. Histology and electron microscopy of insulinoma tissue retrieved after long-term implantation showed functionally active endocrine cells and no evidence of graft rejection. In vitro perifusion gave similar results for encapsulated and nonencapsulated insulinoma tissue. The amount of insulin secreted was quite variable, and responsiveness of the insulinoma to changes in glucose concentration of the surrounding medium was observed in three out of the five tumors studied. These observations establish the effectiveness of immunoseparation by a synthetic membrane in a pancreatic xenograft model.

Impaired uptake of D-glucose by tumoral insulin-producing cells

At variance with the situation found in normal pancreatic islets, no equilibration of extracellular and intracellular D-glucose concentrations occurs in tumoral insulin-producing cells of the RINm5F line. This unexpected behaviour may account, in part at least, for the abnormal kinetics of glucose utilization in the tumoral cells and their poor secretory response to this hexose.

Five new insulin-producing cell lines with differing secretory properties

Five cell lines have been derived from a rat transplantable islet cell tumour using two different methods. The lines differ in morphology and contain and release different amounts of insulin and glucagon (insulin content, 1-90 pmol/10(6) cells; insulin release, 6-250 pmol/10(6) cells per 24 h; glucagon content, less than 0.005-35 pmol/10(6) cells; glucagon release, less than 0.05-10 pmol/10(6) cells per 24 h). All the lines responded to the presence of the secretagogues leucine (20 mmol/l) plus theophylline (5 mmol/l) by increasing the rate of release of insulin approximately twofold. A high extracellular concentration of potassium (40 mmol/l) caused a three- to tenfold calcium-dependent increase in release of insulin and a parallel release of glucagon. Increasing the concentration of glucose from 2.8 to 16.7 mmol/l did not alter the rate of insulin release by any of the cell lines.

Secretion of chromogranin A by peptide-producing endocrine neoplasms

Chromogranin A, the protein that is co-stored and co-released with catecholamines from the adrenal medulla, has recently been identified in a variety of human endocrine tissues, both normal and neoplastic. We investigated the secretion of chromogranin A by peptide hormone-producing human tumors in studies of patients with the following neoplastic disorders: pheochromocytoma, parathyroid adenoma, primary parathyroid hyperplasia, medullary thyroid carcinoma, thyroidal C-cell hyperplasia, carcinoid tumor, oat-cell lung carcinoma, pancreatic islet-cell tumor, and aortic-body tumor. All these patient groups had elevated concentrations of plasma chromogranin A. We distinguished different forms of immunoreactive plasma chromogranin A by size with the use of gel filtration. Plasma chromogranin A levels were not elevated in patients with diverse "control" conditions--both benign and malignant and both endocrine and nonendocrine--in which peptide hormones are not produced. The sensitivity and specificity of plasma chromogranin A elevations in the diagnosis of peptide-producing endocrine neoplasms were 81 and 100 percent, respectively. The elevation of plasma chromogranin A in our subjects suggests that their neoplasms co-release chromogranin A along with the usual resident hormone of the tumor, that these neoplasms could be characterized as "chromograninomas," and that measurement of plasma chromogranin A may be a useful diagnostic procedure in subjects with endocrine tumors, especially multiple endocrine neoplasia.

Detection of hepatic metastases: analysis of pulse sequence performance in MR imaging

Forty-three patients with liver metastases were imaged using 14 different pulse sequences (average, 7.5 sequences per patient) to allow direct comparison of their performance. "T2-weighted" spin-echo (SE) images, "T1-weighted" inversion recovery (IR) images, and "T1-weighted" SE images were obtained using a wide range of timing parameters. Pulse sequence performance was quantitated by measuring liver signal-to-noise (S/N) ratios and cancer-liver signal difference-to-noise (SD/N) ratios. Data were standardized to reflect a constant imaging time of 9 minutes for all pulse sequences. The SE 2,000/120 (TR [repetition time]/TE [echo time]) sequence resulted in the greatest SD/N ratio of the T2-weighted SE sequences but also yielded the low S/N ratios, poor anatomic resolution, and motion artifacts common to all T2-weighted SE images. IR sequence images were also sensitive to motion artifacts because of the use of a long TR (1,500 msec). Short TR/TE T1-weighted SE sequences (SE 260/18) had the greatest SD/N ratio (P less than .05), S/N ratio, and anatomic resolution. Furthermore, extensive signal averaging appears to be a powerful solution to all types of motion artifacts in the abdomen.

Single channel recordings of potassium currents in an insulin-secreting cell line

Using the patch-clamp technique we observed three distinct classes of K+ channels which were spontaneously active in excised 'inside-out' membrane patches from an insulin-secreting rat pancreatic islet cell line (CRI-G1). Two of these occurred infrequently, one with a conductance of approximately 7 pS, and the other a conductance of 220 pS. The activation of the 220 pS K+ channel was dependent upon the membrane voltage and was sensitive to the concentration of calcium ions at the cytoplasmic surface of the membrane. The third, and by far the most common class of K+ channel, was characterized by its sensitivity to ATP. Application of ATP to the cytoplasmic side of the membrane reversibly inhibited this K+ channel in a dose-dependent manner, but had no effect when applied to the external side. The properties of the ATP-sensitive K+ channel appear to be indistinguishable from those of a channel found in rat neonatal beta cells. Thus this insulin-secreting cell line should prove valuable in the investigation of the role of K+ channels in the regulation of insulin secretion.

Effect of phorbol esters on glucagon secretion from a glucagon-secreting clonal cell line. Synergistic effects of A23187 and theophylline

The cell line In-R1-G9 is one of the clones from the hamster insulinoma cell line, In-111-R1, and it produces glucagon. Phorbol esters markedly enhanced glucagon secretion and the stimulatory effect was found to be correlated to their biological activity as tumor promoters. At a concentration of 200 nM, 12-O-tetradecanoylphorbol 13-acetate (TPA) stimulated glucagon secretion 13-fold more than the control in 10 min. The effect of TPA was not influenced by actinomycin D, cycloheximide, colchicine or vincristine. Depletion of calcium from the incubation medium inhibited TPA-induced glucagon secretion by approximately 50% and dibucaine also suppressed glucagon secretion to 67.4%. An addition of A23187 to TPA induced 150% enhancement over the TPA-stimulated glucagon level, and the maximum secretory response was observed when the cells were stimulated with the simultaneous addition of TPA, A23187 and theophylline.

[Hormone immunocytochemical studies of 46 endocrine tumors of the pancreas in 24 patients]

The aim of this retrospective study was to correlate the results of hormonal immunocytochemistry of 46 endocrine tumors to the corresponding clinical syndromes in 24 patients. They were divided as following: 14 cases of insulinoma, 3 cases of Zollinger-Ellison syndrome, 1 case of glucagonoma, 1 case of carcinoid syndrome and 5 cases without any obvious endocrine manifestations. Each tumor was tested with anti-insulin, anti-glucagon, anti-pancreatic polypeptide, anti-vasoactive intestinal peptide, anti-gastrin immune sera according to the peroxidase-antiperoxidase method. The presence of insulin was proved in 13 of 14 cases of insulinomas and the presence of gastrin in 2 of 3 cases of Zollinger-Ellison syndrome. Among the 5 asymptomatic cases, a somatostatinoma and a vipoma were individualized. More than 50 p. 100 of the tumors showed plurihormonal secretion with one predominantly secreted hormone responsible for the clinical syndrome. This study demonstrated the diversity of the hormonal secretion by some tumors and their metastasis in the same patient. Malignant insulinomas correspond either to poorly secreting tumors or to plurihormonal tumors secreting gastrin and glucagon as well.

The processing of receptor-bound [125I-Tyr11]somatostatin by RINm5F insulinoma cells

The peptide somatostatin (SRIF) is secreted by delta cells of the endocrine pancreas and inhibits the secretion of insulin from pancreatic beta cells. We have previously shown that [125I-Tyr11]SRIF binds to specific, high affinity receptors on RINm5F insulinoma cells and that these receptors mediate the action of SRIF to inhibit insulin release. In the present study we investigated the processing of receptor-bound [125I-Tyr11]SRIF in this clonal cell line. Surface-bound and internalized peptides were distinguished by the ability of an acid/salt solution (0.2 M acetic acid, 0.5 M NaCl, pH 2.5) to dissociate only exposed ligand-receptor complexes. Surprisingly, greater than 80% of saturably bound [125I-Tyr11]SRIF was removed by this acid wash independent of the time or temperature of the binding incubation. In contrast, the processing of receptor-bound [125I]EGF (epidermal growth factor) in RINm5F cells was markedly temperature-dependent. Although over 90% of saturably bound [125I]EGF was dissociated by acid after a 4 degrees C binding incubation, less than 10% was removed by acid treatment after 37 degrees C binding. The radioactivity released upon dissociation of receptor-bound [125I-Tyr11]SRIF was analyzed by high performance liquid chromatography and shown to consist of a mixture of intact peptide (40%) and [125I]tyrosine (60%). However, neither the rate of [125I-Tyr11]SRIF dissociation nor its degradation were affected by NH4Cl, methylamine, or leupeptin at concentrations which inhibited the lysosomal degradation of [125I] EGF. Of 11 other protease inhibitors tested, only the metalloendoprotease inhibitor, phosphoramidon, substantially reduced the degradation of receptor-bound [125I-Tyr11]SRIF. These data indicate that, unlike [125I] EGF, receptor-bound [125I-Tyr11]SRIF is not rapidly internalized by RINm5F cells and is degraded by a nonlysosomal process which may involve a metalloendoprotease.

Glucose-stimulated sequestration of Ca2+ in clonal insulin-releasing cells. Evidence for an opposing effect of muscarinic-receptor activation

Net fluxes of Ca2+ and acid production were studied in clonal insulin-releasing cells (RINm5F) by using colour indicators and dual-wavelength spectrophotometry. After equilibration with a medium containing 10-20 microM-Ca2+, only minimal amounts of Ca2+ (0.08 mmol/kg of protein) were released from the cells by subsequent additions of the respiratory blocker antimycin A and the Ca2+ ionophore A23187. The presence of 20 mM-glucose resulted in an almost 5-fold increase of the acid production and in a stimulated net uptake of Ca2+. The latter process was independent of the extracellular Ca2+ concentration and reached saturation after 20 +/- 1 min, when it corresponded to 1.18 +/- 0.07 mmol of calcium/kg of protein. Whereas the thiol reagent iodoacetamide suppressed the acid production, interference with mitochondrial function by using antimycin A or the uncoupler carbonyl cyanide m-chlorophenylhydrazone had the opposite effect. The latter two drugs induced a selective release of Ca2+ from a pool containing 35% of that taken up during glucose exposure. Most of the remaining Ca2+ was liberated by A23187 or iodoacetamide. Carbamoylcholine was also selective in mobilizing glucose-stimulated calcium, but this calcium (17%) appeared to originate from the pool insensitive to mitochondrial poisons. The action of carbamoylcholine was blocked by atropine and did not depend on the presence of extracellular Na+. The opposite effects of glucose and muscarinic-receptor activation on a non-mitochondrial calcium pool are consistent with participation of the endoplasmic reticulum in the glucose-induced sequestration of Ca2+ in pancreatic beta-cells.

Specific binding of the C-peptide of proinsulin to cultured B-cells from a transplantable rat islet cell tumor

Specific binding of the C-peptide of proinsulin was evaluated using a transplantable NEDH rat islet cell tumour predominantly composed of insulin-secreting B-cells. Cultured tumour B-cells exhibited greater than 90% viability assessed by trypan blue exclusion, and retained the ability to form tumours with accompanying hypoglycaemia and hyperinsulinaemia after reimplantation. During binding experiments with synthetic rat C-peptide I and iodinated tyrosylated rat C-peptide I, tumour B-cells exhibited 54 +/- 6% specific binding. Displacement of tracer increased with increasing concentrations of unlabelled rat C-peptide I (0.25-1,000 ng/ml), and the specificity of binding was substantiated by reduced displacement with human C-peptide. Scatchard analysis of specific C-peptide binding revealed a curvilinear plot with upward concavity. The demonstration of specific C-peptide binding to insulin-secreting B-cells provides evidence for a physiological role of proinsulin C-peptide.

Pancreatic polypeptide-secreting islet cell tumor. A follow-up report

A case of documented pancreatic polypeptide (PP)-secreting islet cell tumor was followed for 3 years and 8 months until death due to multiple metastases. The patient initially presented with extremely high serum PP levels without clinical symptoms. After resection of the PP-secreting islet cell tumor, serum PP levels gradually decreased to normal levels. Serum PP levels started to elevate 10 months after the surgery, when liver metastases were verified by open biopsy. The patient was treated with streptozotocin (STZ), and normal serum PP levels returned. However, multiple liver and bone metastases were detected 32 months after resection of the tumor, which led to death. The recurrent tumor obtained at autopsy contained very little immunoreactive PP. The effect of STZ on PP secretion by the islet cell tumor is discussed.

Regulation of insulin mRNA abundance and adenylation: dependence on hormones and matrix substrata

The insulin mRNA levels of rat insulinoma cell lines increased six- to eightfold, and the cells entered a transient state of growth arrest when they were cultured in serum-free, hormonally defined medium and on an extract of extracellular matrix derived from a basement membrane-secreting tumor line, EHS. Insulinoma cultures in growth arrest responded to glucose with a two- to threefold increase in insulin secretion associated with an insulin mRNA that contained a poly(A) tail that was 120 to 140 bases longer than normal.

Stimulation of insulin secretion by a rapid intravenous calcium infusion in patients with beta-cell neoplasms of the pancreas

The effects of calcium on fasting plasma insulin and glucose levels were compared in 16 normal subjects and 11 patients with beta-cell neoplasms of the pancreas. Calcium was administered iv either as a rapid calcium infusion (RCI; 2 mg/kg in 1 min) or as a long calcium infusion (LCI; 12 mg/kg in 3 h). In normal subjects, the RCI produced a rise in mean plasma insulin from 11 +/- 1 (+/- SEM) microU/ml basally to a peak of 18 +/- 2 microU/ml (P less than 0.001). No consistent pattern of change in insulin levels occurred during the LCI, and plasma glucose levels did not change significantly with either test. In the patients with beta-cell neoplasms, the RCI resulted in a rapid increase in mean plasma insulin from 36 +/- 6 microU/ml to a peak level of 312 +/- 67 microU/ml (P less than 0.002). With the LCI, a more gradual rise in insulin from 35 +/- 11 to 92 +/- 36 microU/ml occurred (P less than 0.002). The mean increase in insulin in the patients with beta-cell neoplasms was significantly greater for the RCI than for the LCI (P less than 0.01). Pronounced increments in plasma insulin occurred in all 11 patients after the RCI, but in only 3 of 8 patients during the LCI. Plasma glucose levels declined significantly from 69 +/- 7 to 56 +/- 8 mg/dl during the RCI (P less than 0.05) and from 69 +/- 8 to 49 +/- 7 mg/dl during the LCI (P less than 0.005). Symptomatic hypoglycemia developed in 3 patients during the LCI but did not occur after the RCI. These data indicate that calcium is a more effective insulin secretagogue in patients with beta-cell neoplasms when administered as an RCI than as an LCI, and suggest that the RCI may be a useful test for the diagnosis of insulin-secreting tumors.

Watery diarrhea syndrome caused by multihormonal malignant pancreatic islet cell tumor secreting somatostatin, vasoactive intestinal peptide, serotonin, and prostaglandin E--a clinicopathological, biochemical, immunohistochemical, and ultrastructural study

The pathophysiological, biochemical, histological, ultrastructural, and immunohistochemical characters of a case of malignant pancreatic islet cell tumor with watery diarrhea syndrome were carefully investigated. Four hormones or mediators--somatostatin (SST), vasoactive intestinal peptide (VIP), serotonin, and prostaglandin E--were markedly elevated in the circulation. The diagnosis was further confirmed by exploratory laparotomy and autopsy. The contents of SST and VIP in tumor tissues were very high. Gel chromatography of tumor extract revealed single peaks for both SST and VIP. Immunohistochemical studies of tumor tissues showed numerous immunoreactive cells to anti-SST, moderate amount of VIP-positive cells, and a few hCG-, insulin-, and glucagon-positive cells. In conclusion, this is an unusual case of Verner-Morrison syndrome in which three kinds of bioactive hormones or mediators were simultaneously secreted; peptides, amine, and prostaglandin.

[Endocrine pancreatic tumor secreting somatostatin and somatocrinin]

A case of endocrine pancreatic tumour secreting the 2 antagonistic peptides that regulate growth hormone, somatostatin and somatocrinin, is reported. Such tumours are extremely rare and only one other case has been published so far, although pancreatic malignant tumours frequently secrete several hormones. In our patient, the association of diabetes with steatorrhoea, hypochlorhydria, anaemia and biliary lithiasis suggested hypersecretion of somatostatin. Acromegaly, suggested by clinical signs, was confirmed by an excess of growth hormone and somatomedin, and pre-operative somatrocrinin assay confirmed its extra-pituitary origin. Finally, the presence of hyperparathyroidism due to parathyroid gland hyperplasia and of a Recklinghausen disease constituted a multiple endocrine neoplasia syndrome. The significance and implications of this double secretion in vivo are discussed.

Effects of zinc during culture of an insulin-producing rat cell line (RINm5F)

The effects of various Zn2+ concentrations on cell proliferation, insulin secretion and contents of insulin and zinc were studied in a clonal cell line (RINm5F) established from a transplantable rat islet tumor. The RINm5F cells were equally effective in proliferating and releasing insulin at zinc concentrations ranging from 0.013 to 0.073 mM. The percentage of cells able to exclude trypan blue was significantly less in cultures with 0.073 mM Zn in the medium. Increasing the extracellular concentrations of Zn2+ to 0.044 and 0.073 mM, respectively, resulted in a 40-60% reduction in the cellular content of insulin. There was a significant increase (73%) in the cellular content of zinc only when increasing the extracellular concentration of the element to 0.073 mM. The addition of 0.2 mM EGTA to a zinc-deficient medium had no effect on proliferation, insulin release or content of insulin and zinc, indicating the presence of a stable endogenous pool of zinc maintaining the function of the RINm5F cells for at least 5 days in culture.

Pancreatic polypeptide in islet cell tumors. Morphologic and functional correlations

Twelve islet cell tumors and one islet cell hyperplasia were studied with immunocytochemical and radioimmunoassay methods. With immunocytochemical staining, all six insulinomas, one mixed insulinoma-glucagonoma, and four gastrinomas were positive for insulin, insulin and glucagon, and gastrin, respectively. Pancreatic polypeptide (PP) was positive in three insulinomas and one mixed insulinoma-glucagonoma. All of the tumors were positive for neuron-specific enolase (NSE). Radioimmunoassays of tissue extracts further disclosed that all functioning tumors contained more than one pancreatic hormone. PP concentrations of two insulinomas and one mixed insulinoma-glucagonoma were higher than that of normal control pancreases. A study of protein meal-stimulated PP secretion revealed that three of the insulinoma cases and two gastrinoma cases exhibited higher plasma PP levels than the age-matched controls. The findings suggest that: both functioning and nonfunctioning islet cell tumors derive from neuroendocrine cells positive for NSE; all functioning islet cell tumors appear to contain PP in the tumor tissue as a minor component; as many as 70% of the patients with islet cell tumors present with abnormally higher plasma PP levels after protein meals; and a study of meal-stimulated PP secretion may well be used as a marker for the presence of functional islet cell tumors.

Pancreatic islet cell carcinoma with gastrin and vasoactive intestinal polypeptide production

The case history of a patient with an islet cell carcinoma, which produced both gastrin and vasoactive intestinal polypeptide (VIP), is presented. Although several examples have been observed of the combined production of these hormones by pancreatic endocrine tumors, few reports have related the clinical details of such cases. Resolution of diarrhea occurred in our patient after institution of nasogastric suction and cimetidine therapy, suggesting that gastric hypersecretion, rather than VIP activity, accounted for this problem. Chemotherapy with streptozotocin and 5-fluorouracil was highly effective in ameliorating clinical symptoms, diminishing serum levels of gastrin and VIP, and greatly reducing the bulk of metastatic disease in this case.

Molecular forms of glucagon-like peptide-1 in human pancreas and glucagonomas

The structure of human preproglucagon, as deduced from nucleotide sequencing of the preproglucagon gene, contains two glucagon-like peptides (GLP-1 and GLP-2) in the portion C-terminal to glucagon. A rabbit antiserum was raised against synthetic GLP-1-(1-19) which had 20% cross-reactivity with synthetic GLP-1 and des-Gly37-GLP-1 amide, two possible forms of the GLP-1 whole molecule, but no significant cross-reactivity with glucagon or other pancreatic peptides. Immunocytochemistry revealed that the distribution of GLP-1-(1-19) immunoreactivity followed that of glucagon-like immunoreactivity in the normal human pancreas and in two human glucagon-secreting pancreatic tumors. Chromatography of human pancreas extracts on Sephadex G-50 gave peaks of cross-reactivity at Kav values of 0.06-0.16, 0.34-0.39, 0.54-0.58 (the elution position of synthetic GLP-1), and 0.64-0.70. The concentration of immunoreactivity in the Kav 0.54-0.58 peak measured by RIA using GLP-1 or des-Gly37-GLP-1 amide as standard was 94 +/- 7 pmol/g (mean +/- SEM), while the total pancreatic glucagon content was 4.8 +/- 0.8 nmol/g. One extract of a human glucagon-secreting pancreatic tumor contained a prominent peak of GLP-1-(1-19) peptide cross-reactivity with properties identical to those of GLP-1 or des-Gly37-GLP-1 amide on gel filtration and reverse phase high pressure liquid chromatography, but another tumor contained a preponderance of cross-reactive forms of greater molecular size. Pretreatment plasma from three patients with radiological and biochemical evidence of glucagon-secreting tumors contained a peak of cross-reactivity with the chromatographic properties of intact GLP-1. The low concentrations of intact GLP-1 in normal pancreas compared with pancreatic glucagon concentrations suggest that the majority of the proglucagon is cleaved in a manner that does not produce GLP-1, as defined by its delimiting pairs of basic amino acid residues.

The insidious development of symptomatic secondary hormone syndromes in patients with malignant endocrine tumors

Endocrine tumors may produce secondary or "ectopic" hormones that cause paraneoplastic syndromes. Such syndromes may be confused with more common complications related to a patient's tumor, and thus escape detection and appropriate treatment. The secondary hormone secretion responsible for these syndromes often occurs late in the course of such diseases and presents in an insidious manner. Two patients are presented that illustrate these points. The first, a woman with medullary carcinoma of the thyroid (MCT), developed a syndrome secondary to ACTH secretion that was confused initially with the changes caused by the massive diarrhea that accompanies MCT. The second, a man with malignant glucagonoma, is the first with this disease to have developed symptomatic hyperinsulinemia as a late complication. We stress the clinical courses of these patients and note that treatment of these syndromes may improve the quality of patients' lives.