Carcinoid cells

Ishizuka J, Beauchamp RD, Townsend CM Jr, Greeley GH Jr, Thompson JC. Receptor-mediated autocrine growth-stimulatory effect of 5-hydroxytryptamine on cultured human pancreatic carcinoid cells. J Cell Physiol 1992 150 1-7. 

Mast cell or basophil leukemia Carcinoid syndrome Thyroid carcinoma Pheochromocytoma... 

A number of genetic diseases that result in defects of tryptophan metabolism are associated with the development of pellagra despite an apparently adequate intake of both tryptophan and niacin. Hartnup disease is a rare genetic condition in which there is a defect of the membrane transport mechanism for tryptophan, resulting in large losses due to intestinal malabsorption and failure of the renal resorption mechanism. In carcinoid syndrome there is metastasis of a primary liver tumor of enterochromaffin cells which synthesize 5-hydroxy-tryptamine. Overproduction of 5-hydroxytryptamine may account for as much as 60% of the body s tryptophan metabolism, causing pellagra because of the diversion away from NAD synthesis. 

ACTH-secreting non-pituitary tumors (ectopic ACTH syndrome)—15% of cases of endogenous Cushing s syndrome usually from small cell lung carcinoma, bronchial carcinoids, pheochromocytoma, or thymus, pancreatic, ovarian, or thyroid tumor. The tumor is usually disseminated (difficult to localize). 

Intestinal pseudoobstruction is also part of paraneoplastic syndromes. The anti-/zu antibodies are useful to indicate this condition, as shown in bronchial small cell carcinoma [171], In pheochromocytoma [172] and carcinoid [173] neuromediators affecting small bowel motility are produced by the tumor cells. Intestinal pseudoobstruction has also been reported in neuroblastoma [174],... 

Uses Pancreatic islet cell tumors carcinoid tumors Action DNA-DNA (int -strand) cross-linking DNA, RNA, protein synth inhibitor Dose Per protocol -1- in renal failure Caution w/ renal failure [D, /-] Contra w/ rotavirus vaccine, PRG Disp Inj SE N/V/D, duodenal ulcers, depression, X BM rare nephrotox (proteinuria azotemia dose related), hypophosphatemia dose limiting hypo-/hypCTglycemia inj site Rxns Interactions t Risk of nephrotox W/... 

Streptozocin produces remission in 50 to 60% of patients with islet cell carcinomas of the pancreas. It is also useful in malignant carcinoid tumors. 

Stimulates granulocyte and macrophage production after chemotherapy Islet cell pancreatic carcinoma, malignant carcinoid tumor Breast cancer... 

C. Carcinoid tumors arise from neuroendocrine cells of the gut and secrete serotonin and gastrointestinal hormones, which activate the gastrointestinal tract and result in diarrhea. Most of these tumors have receptors for somatostatin, which inhibit secretion when activated, resulting in reduced activity of the gut. Octreotide is a stable analogue of... 

Histamine is formed by decarboxylation of the amino acid l -histidine, a reaction catalyzed in mammalian tissues by the enzyme histidine decarboxylase. Once formed, histamine is either stored or rapidly inactivated. Very little histamine is excreted unchanged. The major metabolic pathways involve conversion to /V-methylhistamine, methylimidazoleacetic acid, and imidazoleacetic acid (IAA). Certain neoplasms (systemic mastocytosis, urticaria pigmentosa, gastric carcinoid, and occasionally myelogenous leukemia) are associated with increased numbers of mast cells or basophils and with increased excretion of histamine and its metabolites. 

Serotonin is an important neurotransmitter, a local hormone in the gut, a component of the platelet clotting process, and is thought to play a role in migraine headache. Serotonin is also one of the mediators of the signs and symptoms of carcinoid syndrome, an unusual manifestation of carcinoid tumor, a neoplasm of enterochromaffin cells. In patients whose tumor is not operable, a serotonin antagonist may constitute a useful treatment. 

The importance of ERK activation by the 5-HT1A receptor is highlighted by the observation that the receptor can stimulate proliferation of T-lymphocytes (13), pancreatic carcinoid tumor cells (52), human small cell lung carcinoma cells (53), and transfected cell lines (25,54). In contrast, endogenous lymphocyte 5-HT1A receptors have been implicated in the inhibition of mitogenesis (55). 

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