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

Twelve parathyroid chief cell adenomas from patients with primary hyperparathyroidism were incubated in a tissue culture system in the presence of different calcium concentrations and for various time periods. The endocrine response of the tissue was examined electron microscopically and radioimmunologically. After incubation in a medium of low calcium concentration the parathyroid adenomas showed ultrastructural signs of stimulation with proliferation of the hormone-synthesizing organelles. The development of the ultrastructural response could first be observed after four hours and increased up to several days. Radioimmunologically, an increase of the hormone secretion could be demonstrated. Converse results were obtained after incubation of the tumor tissue under suppressive culture conditions. To check for de-novo synthesis of the hormone released the tissue was incubated in a 75Se-methionine-containing medium. This resulted in radioactivity of the secreted parathyroid hormone, indicating de novo synthesis in our culture system. The biological potency of the released hormone was demonstrated by comparison of the PTH out of the medium with the international human MRC standard using two different radioassays.
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PMID:Correlation of electron microscopic and secretory response of human parathyroid adenomas with different calcium concentrations in organ culture. 15 Jan 11

Long-term epidemiological and laboratory studies were carried out in a kindred with familial pheochromocytoma associated with von Hippel-Lindau disease. Thirteen members were affected by the syndrome and the trait appears to be transmitted in an autosomal dominant fashion. Of 13 patients, 7 had pheochromocytoma alone. Of the remaining six patients, one had pheochromocytoma combined with von Hippel-Lindau disease, four had pheochromocytoma with retinal disease only, and a single patient had a retinal lesion without pheochromocytoma. In four patients, pheochromocytoma antedated the development of retinal lesions. Ten members also had mild hypercalcemia without accompanying elevations of PTH in the 4 patients in whom this was determined. In all, hypercalcemia was corrected with removal of tumors, and no patient had a return of hypercalcemia in the absence of recurrent increases in urinary catecholamines. The clinical presentations in 12 patients varied markedly, as did their urinary excretion rates of norepinephrine, epinephrine and their metabolites. However, an analysis of the data revealed significant correlations not previously described between the urinary excretion of free catecholamines (norepinephrine plus epinephrine), blood pressure, the free catecholamine content of the tumor and the age of the patient. Urinary excretion of free norepinephrine plus epinephrine appear to be decreased with advancing age (p less than 0.001). Both systolic and diastolic blood pressures and the age of the patient were inversely correlated (p less than 0.01). A significant inverse relationship between the tumor content of free catecholamines and the age of the patients was, although to a lesser degree, also present (p less than 0.05). As a whole, the size of the tumors and their norepinephrine content were not correlated. We present a concept that, in familial pheochromocytoma, the metabolism of catecholamines is altered by the process of aging, and that this change modifies the clinical presentations of the disease.
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PMID:Familial pheochromocytoma, hypercalcemia, and von Hippel-Lindau disease. A ten year study of a large family. 44 57

Various hormones have been implicated in the genesis of hypercalcemia in patients with malignancy. Ectopic secretion of PTH by tumor has been documented in only a few patients; rather, elevated levels of circulating iPTH have been presumed to reflect tumor production of hormone in most patients. Small fragments of PTH, as well as polypeptides larger than native PTH, have been described; their biological roles are unclear. The pattern of immunoreactivity, however, has been used to differentiate patients with ectopic hyperparathyroidism from patients with concomitant primary hyperparathyroidism. Vitamin D-like sterols produced by breast cancer seldom reach plasma levels necessary for physiological effects. Members of the prostaglandin family have been proposed to induce hypercalcemia through osteoclast activation or alteration of the immune system and also to affect the frequency of bone metastases. At present, no direct evidence is available to prove a direct role for these effects and prostaglandins are most useful as possible indicators of disease activity.
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PMID:Mechanisms of hypercalcemia in malignancy. 65 92

The immunoreactive parathyroid hormone (iPTH) in the plasma of hyperparathyroid man consists largely of carboxyl (COOH)-terminal fragments of the hormone. Although these fragments have been thought to arise principally or solely from peripheral metabolism of intact human PTH {hPTH(1-84)} secreted from the parathyroid gland, there is disagreement about the source of iPTH fragments in vivo. To reexamine this question, we fractionated peripheral and thyroid or parathyroid venous effluent sera from four patients with primary hyperparathyroidism using a high-resolution gel filtration system (Bio-Gel P-150 columns run by reverse flow). The column effluents were analyzed using two PTH radioimmunoassays, one directed toward the amino(NH(2))-terminal region of the molecule, the other toward the COOH-terminal region. In all four thyroid or parathyroid venous effluent sera studied, iPTH was 9-180 times higher than in peripheral serum from the same patient; after fractionation, hPTH(1-84) accounted for only a portion of the total iPTH (35-55% with the assay directed toward the COOH-terminal region of hPTH, >90% with the NH(2)-terminal directed assay.) The remaining iPTH eluted from Bio-Gel P-150 after hPTH(1-84) as NH(2)-or COOH-terminal hPTH fragments. These results suggest that parathyroid tumors secrete large quantities of hPTH fragments. Based on estimates of their molar concentrations in serum, tumor-secreted COOH-terminal hPTH fragments could account for most of these peptides in peripheral serum if their survival times were, as estimated by several other workers, 5-10 times that of hPTH(1-84). We conclude that, in contrast to published information, secretory products of hyperfunctioning parathyroid tissue are probably a major source of serum PTH immunoheterogeneity.
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PMID:Immunoheterogeneity of parathyroid hormone in venous effluent serum from hyperfunctioning parathyroid glands. 91 3

Injection of parathormone and thyrocalcitonin into rats with DMBA induced sarcomas resulted in a considerable stimulation of the metastasization process. It was found that the level of total Ca++ in tumor tissue was reduced under the influence of PTH. Under conditions of chronic exogenous hyperparathyroidism autoimmunereactions were suppressed. A prolonged administration of TCT did not alter considerable the total Ca++ content in tumor and markedly activated the autoantibody production in immunocompetent cells.
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PMID:[The effect of hormones regulating calcium metabolism on the growth and metastasis of experimental tumors]. 110 36

Humoral hypercalcemia of malignancy (HHM) is at least partly caused by tumor secretion of PTH-related peptide (PTHrP), but there is growing evidence for cosecretion with PTHrP of other bone-resorbing peptides, such as the cytokine interleukin-1 alpha (IL-1 alpha). Administration of PTHrP in vivo and in vitro generally mimics the actions of PTH itself, with increases in both resorption and formation of bone. However, bone in HHM is characterized by uncoupling of bone turnover, with increased resorption and decreased formation. We performed experiments to determine whether IL-1 alpha might alter the effects of PTHrP and produce uncoupling. Thus, we administered to 100-g male rats by sc osmotic minipumps synthetic PTHrP-(1-34) alone (2 micrograms/100 g/day), recombinant IL-1 alpha alone (1.5 micrograms/100 g/day), both peptides together at the previous doses, or vehicle only. We infused 5 groups of 12 rats each (PTHrP, IL-1 alpha, PTHrP plus IL-1 alpha, ad libitum fed control, and controls pair-fed to the PTHrP plus IL-1 alpha group) for 14 days. At the end of the study, blood and urine were taken for chemical measurements, and tibias and femurs were harvested for histomorphometry and extraction of RNA from periosteal cells. As expected, PTHrP induced hypercalcemia, relative hypophosphatemia, phosphaturia, and reduced bone mass. Osteoblast number was increased, but osteoclast number was not. Indices of bone formation were unchanged or reduced. The dose of IL-1 alpha chosen had no statistically significant effect, except for reduced longitudinal bone growth, but when combined with PTHrP, IL-1 alpha reduced hypercalcemia, hypophosphatemia, and phosphaturia. In contrast to the blood and urine effects, IL-1 alpha did not interact significantly with PTHrP's effect on bone measurements. Northern analysis of periosteal cell mRNA showed that PTHrP reduced expression of osteocalcin, but not glyceraldehyde-3-phosphate dehydrogenase; IL-1 alpha had no additional effect. These data suggest that 1) continuously administered PTHrP alone may induce uncoupled bone turnover with decreased cortical bone formation; 2) IL-1 alpha appears to inhibit strongly the renal effects of PTHrP and weakly (if at all) its actions on bone and, thus, to decrease its hypercalcemic, phosphaturic, and hypophosphatemic actions; and 3) cosecretion of IL-1 alpha, and possibly other peptide cytokines, with PTHrP may modify the clinical expression of HHM.
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PMID:Inhibition by human interleukin-1 alpha of parathyroid hormone-related peptide effects on renal calcium and phosphorus metabolism in the rat. 131 27

An unusual association of a secreting renal oncocytoma and a parathyroid adenoma is described. The high level of hypercalcemia and of blood parathormone (PTH 44-68), partially reduced by nephrectomy and totally normalized by parathyroidectomy, as well as the renal tumor PTH evaluation and the ultrastructural features showing secretory granules in oncocytic cells of kidney, advocate for a double site of PTH secretion. Removal of both tumors permits a complete recovering.
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PMID:[Association of a secreting oncocytic tumor of the kidney and a parathyroid adenoma]. 135 Sep 10

In order to prevent aluminum toxicity induced by the association of aluminum phosphate binder with 1 alpha(OH) vitamin D3 derivatives and the use of deferoxamine with its own hazards to diagnose and treat this toxicity, we have shown in 1982 that it was possible to replace the iatrogenic association of aluminum phosphate binder with 1 alpha OH vitamin D derivatives by oral calcium carbonate taken with the meals in order to bind phosphate and correct the negative calcium balance. This led to the disappearance of the crippling aluminic osteomalacia and adynamic bone diseases in our center. The effectiveness of CaCO3 without 1 alpha(OH)D3 derivatives in the control of hyperparathyroidism in dialysis patients has been proven by the appearance in four patients of our dialysis population of an histological idiopathic adynamic bone disease associated with relative hypoparathyroidism, and by the finding that more than 50% of our dialysis population treated by this sole treatment have plasma concentration of intact PTH below twice the upper limit of normal (that is, the threshold above which only significant histological osteitis fibrosa is observed). Besides the compliance problem, the limit of CaCO3 is the occurrence of hypercalcemia which occurs in about 8% of the measurements. Since calcium acetate binds twice as much phosphate for the same dose of elemental calcium as CaCO3, its use has been recommended. However, clinical experience has shown that in spite of the fact that half the dose of calcium element given as acetate does actually control predialysis plasma phosphate as well as CaCO3, the incidence of hypercalcemia is not decreased, probably because calcium availability at the alkaline pH of the intestine is much greater with Ca acetate. When hypercalcemia is frequent (and not explained by autonomized hyperparathyroidism, adynamic bone disease, overtreatment with vitamin D, granulomatosis or neoplasia) it is necessary either to decrease the dose of calcium and complete the necessary binding of phosphate by adding small doses of Mg(OH)2 or Mg carbonate, provided the dialysate Mg is decreased to 0.2 to 0.35 mmol/liter to prevent hypermagnesemia or to decrease the dialysate calcium (DCa) concentration. The decrease of DCa can be made either just when hypercalcemia occurs or on a systemic basis according to the amount of CaCO3 used and to the necessity of associating 1 alpha(OH) vitamin D3 derivatives.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Use of alkaline calcium salts as phosphate binder in uremic patients. 140 82

The antineoplastic properties of suramin, a polyanionic agent with demonstrated antigrowth factor activity, are under evaluation in vitro, in vivo, and in clinical trials. Suramin has been shown to have antitumor activity in patients with advanced, hormone refractory prostate cancer. During these trials, significant resolution of osseous pain was observed in nearly three quarters of the patients treated with suramin. To evaluate the effect of suramin on bone cells, we studied the effect of suramin on bone resorption in a neonatal mouse calvarial assay. Suramin inhibited bone-resorbing activity in a dose-related fashion and had an additive effect with calcitonin. Calvaria pretreated with suramin had less bone-resorbing activity, fewer attached osteoblasts, and less medium alkaline phosphatase activity than control calvaria. Suramin also inhibited osteoclastic release of tritiated proline from labeled bone in a dose-dependent fashion. The effect of metastatic prostate carcinoma on bone is incompletely understood, but may be moderated by tumor-produced factors and/or cytokines. The effects of several such agents, therefore, were examined in combination with suramin. Bone resorption induced by PTH, epidermal growth factor, tumor necrosis factor, and a tumor-produced factor, PTH related-protein, was blocked by suramin. The ability of suramin to inhibit the bone-resorbing effects of several cytokines suggests that its mechanism may involve direct action on bone metabolism. Autoradiography performed on calvaria treated with labeled suramin demonstrated heavy deposition of suramin on the outer surface of the matrix, adjacent to osteoblasts and osteoclasts lining the outer table, suggesting that bone cells may be subject to high local concentrations of the drug, in keeping with this hypothesis.
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PMID:Suramin inhibits bone resorption and reduces osteoblast number in a neonatal mouse calvarial bone resorption assay. 142 26

Hyperparathyroidism is a central component of multiple endocrine neoplasia type 1 (MEN 1), and both sporadic and familial forms of parathyroid disease may share certain pathogenetic features. We recently identified a gene that is clonally rearranged with the PTH locus in a subset of sporadic parathyroid adenomas. This candidate oncogene, PRAD1 (previously D11S287), appears to contribute to parathyroid tumorigenesis in a fashion analogous to activation of C-MYC or BCL-2 by rearrangement with tissue-specific enhancers of the immunoglobulin genes in B-lymphoid neoplasia. The PRAD1 gene maps to 11q13 and has been linked to the BCL-1 breakpoint locus, although not to the most tightly linked MEN 1 markers, by pulsed field gel electrophoresis. PRAD1 may, in fact, be the long-sought BCL-1 lymphoma oncogene. PRAD1 encodes a novel type of cyclin protein and thus may normally function in controlling the cell cycle, perhaps through direct interaction with cdc2 or a related kinase. PRAD1's possible primary, or more likely secondary, involvement in the pathogenesis of MEN 1-related tumors is unknown and under investigation.
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PMID:PRAD1 (cyclin D1): a parathyroid neoplasia gene on 11q13. 148 73


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