Purpose: A retrospective analysis of the toxicity and efficacy of temozolomide in advanced neuroendocrine tumors. Experimental Design: Thirty-six patients with advanced stages of neuroendocrine tumor (1gastric, 7 thymic and 13 bronchial carcinoids, 12 pancreatic endocrine tumors, 1 paraganglioma, 1 neuroendocrine foregut, and 1 neuroendocrine cecal cancer) were treated with temozolomide (200 mg/m 2

Pancreatic 13 cells exhibit oscillations in electrical activity, cytoplasmic free Ca2+ concentration ([Ca2+];), and insulin release upon glucose stimulation. The mechanism by which these oscillations are generated is not known. Here we demonstrate fluctuations in the activity of the ATPdependent K+ channels (KATP channels) in single 13 cells subject to glucose stimulation or to stimulation with low concentrations of tolbutamide. During stimulation with glucose or low concentrations of tolbutamide, KATP channel activity decreased and action potentials ensued. After 2-3 min, despite continuous stimulation, action potentials subsided and openings of KATP channels could again be observed. [Ca2+], was measured at 37°C in fura-2-loaded 3 cells. Before the experiments, cells were exposed to 1.5 ,u M fura-2/AM for 20 min at 37°C. The f3 cells, attached to coverslips, were then transferred to a perifusion chamber (7). The [Ca2+]i measurements were carried out essentially as reported (7)

Using dual excitation and fixed emission fluorescence microscopy, we were able to measure changes in cytoplasmic free Ca 2؉ concentration ([Ca 2؉ ] i ) and mitochondrial membrane potential simultaneously in the pancreatic ␤-cell. The ␤-cells were exposed to a combination of the Ca 2؉ indicator fura-2/AM and the indicator of mitochondrial membrane potential, rhodamine 123 (Rh123 [Ca 2ϩ ] i in pancreatic ␤-cells using the dye fura-2 (4, 6, 7). Measurements of mitochondrial membrane potential in these cells, using the lipophilic cationic dye rhodamine 123 (Rh123), have also been reported (8). Simultaneous measurements of [Ca 2ϩ ] i and mitochondrial membrane potential in the pancreatic ␤-cell would be of great interest and could provide important information about the possible correlation between mitochondrial responses to glucose stimulation and events at the plasma membrane of the ␤-cell. Such simultaneous measurements have recently been performed in neurons (9, 10) and in mouse ␤-cells (11). To investigate the relationship between mitochondrial membrane potential and [Ca 2ϩ ] i in the ␤-cell, we loaded ␤-cells with fura-2 and Rh123 and applied the method of simultaneous measurements of these two parameters. Our methodological evaluation included an investigation of cellular Rh123 distribution as observed with confocal microscopy. We also estimated the contribution to emitted light from both dyes at the respective excitation wavelength, allowing us to correct for contaminating fluorescence. EXPERIMENTAL PROCEDURESAll reagents were of analytical grade and Millipore water was used. Bovine serum albumin fraction V was from Sigma, collagenase was from Roche Molecular Biochemicals, and fura-2/AM as well as Rh123 were from Molecular Probes Europe BV (Leiden, The Netherlands). Statistical summaries of data are expressed as the mean Ϯ S.E. Where appropriate, the possible statistical significance of differences between two sets of data was tested using Student's t test for unpaired data. In all experimental protocols, ␤-cells from at least three different animals were used, if not otherwise specified.Animals and Preparation of Cells-Adult obese mice (gene symbol ob/ob) of both sexes were obtained from a local colony and starved for 24 h. The animals were killed by decapitation and the islets isolated using a collagenase technique (12). The islets of these mice contain more than 90% ␤-cells (13). A cell suspension was prepared and washed essentially as described previously (14). The cells were suspended in RPMI 1640 culture medium (Flow Laboratories) containing 11 mM glucose supplemented with 10% (v/v) fetal bovine serum, 2 mM Lglutamine, 50 IU/ml penicillin, and 50 g/ml streptomycin (Life Technologies, Inc.). The cell suspension was seeded onto coverslips, and the cells allowed to attach for 2 h and then cultured for up to 3 days in the above medium.Media-The basal medium used for preparation of cells as well as experiments was a HEPES buffer, pH 7.4, with Cl Ϫ as the sole anion (15), containing 3 mM glucose, 1.28 ...

Glucagonomas represent 7% of our comprehensive referral material of endocrine pancreatic tumors. Necrolytic migratory erythema was a common finding (52%) and diabetes less frequent at presentation than previously reported. Tumors were positive on somatostatin receptor scintigraphy and objective responses were seen to chemotherapy.