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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The infusion of calcium results in the release of gastrin, calcitonin, and serotonin from certain nonbeta islet cell tumors of the pancreas, medullary carcinomas of the thyroid, and carcinoid tumors, respectively. In this study, intravenous infusion of either calcium chloride or calcium aluconate in a patient with an islet-cell carcinoma resulted in a simultaneous rise in plasma immunoreactive insulin and proinsulin, and concurrent hypoglycemia. After resection of the tumor, calcium infusion caused no change in these parameters. Similarly, calcium infusion caused no change in plasma insulin or glucose in normal volunteers. The response of this tumor suggests that calcium infusion may be a useful provocative test to detect insulin-secreting neoplasia. A derangement of the stimulus-secretion coupling mechanism for insulin in the tumor cells may be responsible for their abnormal sensitivity to calcium ion.
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PMID:Insulin and proinsulin release during calcium infusion in a patient with islet-cell tumor. 16 54

A 72-year-old black woman presented with huge enlargement of the right breast beginning approximately 30 years earlier and progressively enlarging over the years. The breast was stony hard, painless, and inconvenient only because of size and weight. Simple mastectomy was done and pathologic examination showed a benign mixed tumor with large areas of pseudocartilage, osteoid, and bone formation. Preoperatively the serum calcium was 11.0 mg/100 ml and alkaline phosphatase, 550 mU/ml (SMA-12). Postoperative course was uneventful and within several weeks the alkaline phosphatase fell to a normal range (35-115 mU/ml). The case presented requires little comment other than its unusual nature and duration. Extensive bone formation was undoubtedly responsible for the elevated alkaline phosphatase and, as expected, it returned to normal limits following excision of the tumor. Simple mastectomy is considered the treatment of choice.
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PMID:Mixed tumor of female breast of unusual duration and size. 16 43

An insulin-producing islet cell tumor of the Syrian hamster has been studied in vitro for its capacity to respond to known stimuli of insulin release. Insulin secretion during short term incubation and perifusion of fragments of tumor was detected by radioimmunoassay. Insulin release was increased 2-4 fold by 40 mM potassium in the presence of calcium, glucose (22 mM), glucagon (0.3-3.0 muM), N6,02'-dibutyryl adenosine 3',5'-monophosphate (cAMP; 6mM), and theophylline (10 mM). Concentrations of glucagon that induced insulin release were also effective in activating adenylate cyclase in the membranes of tumor cells. Thus, this tumor appears to possess a cAMP-mediated mechanism for insulin release. Somatostatin (0.8-25 mum) inhibited glucagon-induced insulin release without altering basal or glucagon stimulated adenylate cyclase activity. It would appear that inhibition of glucagon induced insulin release by somatostatin is not mediated by adenylate cyclase. We propose that insulin release by this tumor is sufficiently similar to that found in normal islets so as to make it a suitable model for biochemical studies that require large quantities of homogeneous tissue.
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PMID:Regulation of in vitro insulin release from a transplantable Syrian hamster insulinoma. 16 25

Supercoiled BK papovavirus DNA was shown to transform hamster kidney cells using the calcium phosphate co-precipitation technique. The transformed cells contained intranuclear T-antigen(s) and rescuable virus and produced progressively growing tumors when inoculated into hamsters. A novel finding was the production in tumor-bearing animals of antinuclear antibody, which reacted against normal, untransformed cells; in addition, tumor serum contained antibody against virus-specific T-antigen(s).
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PMID:Transformation of hamster kidney cells by BK papovavirus DNA. 17 87

A case of watery diarrhea, hypokalemia and hypercalcemia associated with an islet cell tumor was described. A 62-year old man exhibited frequent watery diarrhea and hypokalemia for two years. He had no peptic ulcer and serum gastrin level was normal. His serum calcium was abnormally high and serum phosphate was lowered. He had secretin-like activity in his plasma. Autopsy revealed a small islet cell tumor in the pancreas and several metastatic masses in the liver. Microscopic examination revealed the tumor cell was not beta, alpha nor D cells. By electron microscopy the secretion granules of the tumor cell resembled those of S, M and T cells. It was not possible to decide which of the tree cell types was responsible for the pancreatic cholera.
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PMID:A case of watery diarrhea, hypokalemia and hypercalcemia associated with nonulcerogenic islet cell tumor of the pancreas. 17 23

Studies of TSH release and production were performed in short term monolayer cultures of transplantable, thyroid hormone responsive, thyrotropin (TSH) producing mouse pituitary tumors. These tumors contained large amounts of TSH, small amounts of growth hormone (GH) and no detectable luteinizing hormone (LH), indicating that the predominant hormone product of tumor cells was TSH. The TSH content per tumor cell was similar to that of the normal pituitary where thyrotrophs represent a small fraction of the total cells, suggesting that the TSH content per tumor cell was less than that of the normal thyrotroph. There was a time dependent release and production of TSH by tumor cells in monolayer culture. Thyrotropin releasing hormone (TRH) increased the release into the media and the production of TSH in a dose dependent manner. Maximum effects were noted at 0.2 ng/ml. Thyroid hormones and somatostatin inhibited both basal and TRH induced effects on both TSH release and production. TSH release as induced by TRH was calcium dependent. TSH release was stimulated by ouabain (10(-3)M) and potassium (57 mM), agents known to promote cellular calcium uptake in a calcium dependent manner. These studies indicate that tumor derived cells function in monolayer culture in a similar fashion to normal thyrotrophs. Studies were conducted to test the hypothesis that TRH action is mediated by adenosine 3',5' monophosphate (cAMP). Dibutyryl cAMP (6 mM) and theophylline (10 mM) increased TSH release suggesting that cAMP is involved in TSH release. However, TRH had no detectable effect on tumor cell adenylate cyclase activity or levels of cAMP. In contrast, PGE1 (1-10 mug/ml) stimulated adenylate cyclase activity and elevated cellular levels of cAMP without increasing TSH release. Thus, we are unable to confirm the postulate that cAMP is the intracellular mediator of TRH action.
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PMID:Regulation of thyrotropin (TSH) release and production in monolayer cultures of transplantable TSH-producing mouse tumors. 17 85

The Verner-Morrison Syndrome is a clinically defined entity caused by an islet cell tumor of the pancreas. More than 60 cases have been described so long. The syndrome is characterized by diarrhea, hypokalemia and hypochlorhydria. In addition to a diabetic disposition, raised calcium levels and skin alterations may be present. The diagnosis is a clinical one. A pancreatic tumor should be searched for and removed. Morphologically a benign and a maligne islet cell tumor or a diffuse hyperplasia of the islets of Langerhans can be found. Until now identification of the tumor cells has not been possible. There seems no doubt that the tumor cells produce a peptide hormone. Secretin, gastric inhibitory polypeptide, vasoactive intestinal polypeptide and combinations of hormones are discussed. The results are contradictory. Theories concerning the formal and causal pathogenesis are only incomplete and unproved up to now.
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PMID:[The Verner-Morrison syndrome. The clinical picture and pathologic anatomy]. 17 9

The morphological, ultrastructural, biochemical and electrophysiological properties of B104-F, a clonal cell line derived from a nitrosoethylurea-induced neoplasm in a rat, were studied as a function of the growth phase of the culture. Cells in exponentially growing cultures are mononucleate and produce action potentials when stimulated electrically. Stationary phase cultures contain three types of cells: cells of the first type are mononucleate and have long processes containing microfilaments and many parallel microtubules; cells of the second type are mononucleate but contain no microtubules and few microfilaments; and cells of the third type have ultrastructural features typical of multinucleate, striated myotubes. Multinucleate cells generate action potentials with both sodium and calcium components and are depolarized by acetylcholine. The acetylcholine response is blocked by d-tubocurarine. The specific activity of creatine phosphokinase is nine times higher in stationary phase cultures than in exponentially growing ones while the myokinase specific activity is unchanged. The gamma-aminobutyric acid content of the cells is 3.5- to 26-fold higher in stationary phase than in exponentially growing cultures, depending on the degree of fusion of the culture. The properties of B104-F are discussed in relation to the properties of developing skeletal muscle and of central nervous system cell lines.
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PMID:Development of a clonal myogenic cell line with unusual biochemical properties. 17 72

The effects of trypsin and EDTA on the cell coat of ascites tumor cells were studied by means of biochemical and electron microscopy techniques. EDTA seems to release, by chelation of the Ca2+-bridges, an outer layer of glycoproteins of presumably exogenous origin. On the contrary, trypsin produces a deeper enzymic cleavage which appears to affect the structural integrity of the bilayered cell membrane. The significance of the cell leakage in tumor cells and the effect of EDTA on the modification of this leakage by change of cell membrane permeability are discussed.
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PMID:Cell coat in tumor cells -- effects of trypsin and EDTA: a biochemical and morphological study. 18 64

Osteosarcomas were produced by the intratibial inoculation of New Zealand black rats with Moloney sarcoma virus (MSV) at 1 day and 4 days of age. Radiographic evidence of osteosarcoma development was first demonstrated at 10 to 15 days postinoculation in both groups. Subsequent radiographic and light and electron microscopic evaluation of tumor-bearing rats demonstrated that osteosarcomas in rats inoculated at Day 4 of age were more osteoproliferative osteosarcomas than those in rats inoculated on Day 1. Rats inoculated at 4 days of age lived longer, had more slowly growing osteosarcomas, and developed a consistent tumor-associated cachexia compared to tumor-bearing rats inoculated at Day 1. Both groups of rats had a 93% metastasis rate involving either sublumbar lymph nodes, lungs, or both. Tumor-bearing rats inoculated at 4 days of age had consistent elevations in both urinary hydroxyproline excretion (HOP/CR) and serum alkaline phosphatase levels, and in serum calcium levels at some time points. The high tumor incidence after a short latent period and the morphologic and biochemical similarities between the MSV-induced murine osteosarcoma and the osteosarcoma in human beings makes this discrete tumor and a valuable animal model for the evaluation of new therapeutic regimens.
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PMID:Virus-induced animal model of osteosarcoma in the rat: Morphologic and biochemical studies. 18 16


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