Polypeptide hormone production by “Carcinoid” apudomas and their relevant cytochemistry

Amyloid fibrils in human insulinoma and islets of Langerhans of the diabetic cat are derived from a neuropeptide-like protein also present in normal islet cells.

“…These biochemical forms of amyloid that have been characterized to date are (i) protein AL (derived from immunoglobulin light chains) found in the amyloid of primary amyloidosis and in multiple myeloma patients, (ii) protein AA in secondary (reactive) amyloidosis, (iii) prealbumin (transthyretin) in forms of hereditary polyneuropathy and senile systemic amyloidosis, (iv) P2-microglobulin in the amyloid associated with chronic hemodialysis, (v) gamma trace in the syndrome of hereditary cerebral hemorrhage with amyloidosis, (vi) procalcitonin in medullary carcinoma of the thyroid, and (vii) /3 protein in Alzheimer's disease. Amyloid localized to polypeptide hormone-producing tissues has been proposed to consist of polymerized hormones (18,19). This is best supported by amino acid sequence analysis showing that amyloid fibrils in human medullary carcinoma of the thyroid are derived from procalcitonin (13).…”

Effect of somatostatin on ion transport in the rat colon.

“…Segments of mucosa were mounited in lucite chambers with a surface area of 1.13 cm2 and attached to mucosal and serosal reservoirs containing identical volumes of Ringer's sollutioll, pH 7.4, at 37°C. The composition of the Ringer's solution usedl in these experiments was the following (mM): Na, 140; Cl, 119.8; HCO3, 25; Ca, 1.2; Mg, 1.2; K, 5.2; HPO4, 2.4; H2PO4, 0.4. 5 mM glultamine was added to all Ringer's solutions uised in these experiments.…”

“…These effects make serotonin a prime candidlate for the agent causing diarrhea in the careinoid syndrome, although other agents have leen reported to be elevated in this syndrome (calcitonin, PGE1, and PGF2,, histamiine, etc.) (20)(21)(22)(23)(24)(25)(26). Three of four patients with the carcinoid syndrome were found to have net jejunial fluiid secretion (4,27).…”

“…Thus SRIF may work by inhibiting the release of serotonin, blocking its effect, or both, in the carcinoid syndrome. Alternatively, SRIF may work by inhibiting the release or blocking the effect of some other secretagogue produced by the tumor (20)(21)(22)(23)(24)(25)(26).…”

Neuroendocrine Tumors of the Liver and Pancreas Associated with Elevated Serum Prostatic Acid Phosphatase.

“…In contrast, PAP production has been reported in two cases of islet cell tumor of the pancreas, insuloma and in occasional cells in normal Langerhans islets ( 1 2-14). Therefore, if the primary site of the PAP-producing neuroendocrine tumor in the present case was the pancreas, the tumor cells may have originated from insulin-producing cells, occasional cells of normal Langerhans islets or their ancestral cells (12,29,31). PAPis a sensitive but not a specific marker of prostatic carcinoma (12,32), and high serum PAP associated with normal PSAis characteristic of neuroendocrine tumors of nonprostate origin (9).…”