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

Cortisol production is appropriately maintained by a complex control system which involves primarily the hypothalamus, the pituitary, and the adrenal cortices. Very small quantities of ACTH stimulate cortisol production, and maximum stimulation occurs with serum concentrations of only 3 mU/100 ML. Under normal circumstances, cortisol is secreted in bursts about ten times each day and circulates predominately bound to a specific binding protein which is rather completely saturated. Radioimmunoassay of plasma cortisol is now generally available and is the assay method of choice, but because of the episodic nature of its secretion, random values of plasma cortisol must be interpreted with great reservation, and even the comparison of morning and evening values in assessing circadian rhythmicity is not often helpful. Urinary free cortisol determinations provide excellent discrimination between normal function and all forms of hypercortisolism. Although the response of the adrenal cortices to ACTH may be evaluated in a number of different ways, the simplest but most definitive procedure involves continuous intravenous administration over a 48-hr period. Of the various tests which indirectly assess the potential for ACTH secretion, the use of metyrapone is most helpful. In the test of greatest utility, plasma cortisol and 11-desoxycortisol are determined the morning after a single midnight oral dose of 30 mg/kg. The detection of all forms of pathologic hypercortisolism is still best accomplished by the oral administration of dexamethasone. Plasma cortisol can be determined the morning after a single midnight dose of 1 mg, or urinary 17-hydroxycorticosteroids can be determined after 2 days in which 0.5 mg is given at 6-hr intervals. Patients with hypercortisolism of hypothalamic-pituitary origin usually evidence appropriate suppression of urinary steroids if the dose is increased to 2.0 mg every 6 hr for another 48 hr. In patients who do not suppress on this or even higher doses of dexamethasone, the distinction between those with adrenal tumor and those with the ectopic ACTH syndrome can be accomplished most definitively by the assay of plasma ACTH where this determination is available.
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PMID:Clinical testing of the hypothalamic-pituitary-adrenocortical system in states of hypo- and hypercortisolism. 16 67

Tumor tissues obtained from 4 patients with the ectopic ACTH syndrome were studied for release and synthesis of tumor ACTH, using an in vitro incubation system. The effect of various agents on release of tumor ACTH was evaluated in three cases; beta-MSH released and adenosine 3',5'-monophosphate (cyclic AMP) formed in the tissue were determined in one. Biosynthetic experiments using labeled amino acid incorporation were performed in two cases. Secretion of tumor ACTH was significantly stimulated in all cases by crude rat median eminence extract which was also effective in stimulating beta-MSH secretion associated with elevated tissue cyclic AMP levels in one. Addition of cyclic AMP and dibutyryl cyclic AMP caused a significant increase in release of both tumor ACTH and beta-MSH in one. Biogenic amines (norepinephrine and serotonin) markedly elevated tussie cyclic AMP levels without a corresponding increase of hormone release in one. Incorporation experiments revealed that 3H- or 14C-phenylalanine was incorporated into immunoreactive ACTH of a larger molecular size (big ACTH) in both cases by chromatographic procedures. However, biological activity of big ACTH was found to be undetectable by an in vivo steroidogenic assay. A mild tryptic digestion of the big forms resulted in the appearance of little ACTH to which the major radioactive peak shifted. These data suggest that the mechanism of release of tumor ACTH and beta-MSH is very similar to that of the pituitary, and that intracellular cyclic AMP may in part play some role in release of both hormones. It is also suggested that some ectopic ACTH producing tumors predominantly synthesize big ACTH, a possible precursor of ACTH, with less bioactivity.
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PMID:In vitro release and biosynthesis of tumor ACTH in ectopic ACTH producing tumors. 16 26

The failure of certain adrenal tumors to respond to ACTH was investigated in vivo be administration of corticotropin-(1-24)-tetracosapeptide (ACTH1-24) and dexamethasone and in vitro by studying the binding properties of ACTH1-24 and prostaglandin E1 (PGE1) and their effect on adenylate cyclase activity of the tumors' crude membranes; in addition, in five cases the stimulation of cortisol production in isolated adrenal cells by both hormones and dibuttyryl cyclic adenosine 3',5'-monophosphate (cAMP) was also studied. The results obtained in 13 hormone-producing tumors of the human adrenal cortex, i.e. 10 carcinomas and 3 adenomas, were compared with those found in normal human adrenal glands. According to the adenylate cyclase responses to ACTH1-24 and PGE1, the tumors fall into different categories. In the first group are six rumors in which the adenylate cyclase was stimulated by both ACTH1-24 and PGE; in addition specific binding could be demonstrated for the two hormones in all six. The binding affinity for 125I-ACTH1-24 was found to be about 10 times higher than that for 125I-ACTH11-24. In the one tumor in which the experiment was performed, bound 125I-ACTH1-24 was displaced by ACTH1-10. These results are similar to the ones found in normal human adrenal preparations. For two rumors of the group in which ACTH did not increase steroidogenesis in vivo, the biochemical abnormality might be located beyond cAMP formation. A second group encompasses six tumors in which the steroidogenesis in vivo and the adenylate cyclase activity were insensitive to ACTH1-24 but in which the enzyme was stimulated by PGE1 and NaF. However, these preparations bound 125I-ACTH1-24 and 125I-ACTH11-24, the binding affinity being similar for both peptides but 10 times lower than the one found in normal adrenal cortex for 125I-ACTH1-24. In the only case of this group where it was tested, ACTH1-10 did not displace bound 125I-ACTH1-24. This result strongly suggests the possibility of a modification or a loss of the receptor site that binds the N-terminal sequency (1-10) of ACTH, the biologically active part of the molecule. In the last tumor, both PGE1 and ACTH were unable to stimulate adenylate cyclase activity and steroid production in a preparation of isolated adrenal cells, although steroidogenesis was stimulated by dibutyryl though steroidogenesis was stimulated by dibutyryl cAMP. No specific binding for PGE1 could be demonstrated. However, 125I-ACTH1-24 and 125I-ACTH11-24 were found to be bound to the tumor with the same affinity.
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PMID:ACTH and prostaglandin receptors in human adrenocortical tumors. Apparent modification of a specific component of the ACTH-binding site. 16 92

The ultrastructure of the adrenal cortex was studied by quantitative stereologic techniques in LAF1 mice bearing a transplantable, ACTH-secreting pituitary tumor (AtT). The tumor stimulated a significant increase in volume and surface area of smooth endoplasmic reticulum and mitochondrial membranes in all three zones of the adrenal cortex. Concomitantly, plasma corticosterone was increased significantly in tumor-bearing animals. The AtT was an adenoma of the chromophobe type. Continuity of the nuclear membrane with the rough endoplasmic reticulum was readily observed in tumor parenchymal cells.
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PMID:Quantitative study on the effect of an ACTH-producing pituitary tumor on the ultrastructure of the mouse adrenal gland. 16

Trans-membrane potentials and steroidogenesis were measured in superfused slices of non-tumor and neoplastic human adrenocortical tissue. Non-tumor tissue was obtained at the time for renal transplant or from tissue removed along with tumors. Non-tumor human adrenocortical tissue had electrophysiological and steroidogenic properties similar to those of the rat and rabbit. In normal medium ACTH stimulated steroidogenesis but had no effect on the membrane potential. In K+-free medium, the cells hyperpolarized, and subsequent addition of ACTH caused depolarization. Trans-membrane potentials of adrenocortical tumors were lower than those of non-tumor cells. Ommission of K+ from the medium caused hyperpolairzation of the tumor cells, but the trans-membrane potentials did not reach the values of hyperpolarized non-tumor cells. ACTH, added to the K+-free medium, caused little or no change in membrane potential of tumor cells except in one case of a virilizing adenoma, which responded very much like non-tumor tissue. Except for the virilizing adenoma, tumor tissue slices produced little or no detectable fluorogenic steroid, even in the presence of large amounts of ACTH or cyclic AMP. The virilizing adenoma responded with increased steroidogensis to ACTH and cyclic AMP.
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PMID:Transmembrane potentials and steroidogenesis in normal and neoplastic human adrenocortical tissue. 17 Feb 96

Clinical, laboratory and pathological findings of a patient in bronchial carcinoma with choroidal metastasis were presented. X-ray examination of the chest suggested the tumor shadow in the posterior segmental bronchus of the right upper lobe of the lung (r-B2b), while funduscopy and fluorescein angiography revealed the presence of choroidal tumor. ACTH levels in tumor tissues at autopsy and in serum were measured and definitely demonstrated and elevated. Histopathologically, the primary lesion was r-B2b and diagnosed as a mucocellular type of adenocarcinoma. The choroidal lesion was metastatic carcinoma. Electron microscopic examination of the choroidal lesion reembedded for electron microscopy from celloidin-embedded materials for light microscopy could reveal the presence of characteristic cytoplasmic granules referred to as neurosecretory-type granules. It is extremely rare that a hormone-producing metastatic carcinoma of the choroid from the bronchus has been proved.
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PMID:Electron microscopic demonstration of hormone-producing metastatic carcinoma of the choroid from the bronchus. 17 May 72

The predominant component of immunoreactive ACTH in the plasma of adrenalectomized normal mice and of mice bearing the adrenotropic mouse pituitary tumor, AtT-20, and in extracts of the normal mouse pituitary and pituitary tumor, has an elution volume on Sephadex G-50 gel filtration approximately midway between the void volume and the elution volume of human ACTH (1-39 peptide). The tumor extracts are shown to contain, in addition to this intermediate ACTH, 2 other components of immunoreactive ACTH, one which coelutes with 131I-labeled albumin (big ACTH) and the other with [125I]hACTH (little ACTH). Big and intermediate ACTH are urea-stable. Controlled tryptic digestion of mouse-tumor big ACTH results within 10 seconds in conversion to an intermediate component followed by continued loss of immunoreactivity. Under the same conditions of tryptic digestion of intermediate ACTH, there is only continuous loss of immuno-reactivity with no change of hormonal form. These findings strengthen the hypothesis that mouse intermediate ACTH is not a precursor for little ACTH.
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PMID:Characterization of mouse ACTH in plasma and in extracts of pituitary and of adrenotropic pituitary tumor. 17 Nov 53

The radioimmunoassay of ACTH was used in a routine laboratory to localize the site of the lesion in 20 patients with Cushing's syndrome. Eight of the patients had no detectable circulating ACTH and had adrenal tumors removed, 12 had high levels and were diagnosed as having pituitary Cushing's syndrome. Very high levels of plasma ACTH were found in eight patients who had primary adrenal insufficiency, while ACTH was undetectable in ten patients with secondary hypoadrenalism. The routine use of this assay in endocrinology should reduce the hospitalization of patients under investigation for disorders of the pituitary--adrenal axis. Eight patients who had the ectopic ACTH syndrome and carcinoma of the lung were found to have very high levels of ACTH with no diurnal variation. Forty-seven patients with oat-cell carcinoma but without evidence of the ectopic ACTH syndrome had normal ACTH levels. A possible role of ACTH and other peptide hormones as tumor markers is mentioned.
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PMID:Application of adrenocorticotropin assays in a routine clinical laboratory. 17 40

Adrenal cell suspensions prepared from rats bearing the MtTF4 tumor failed to increase corticosterone production when exposed to adenosine 3', 5'-cyclic monophosphate (cyclic AMP) or ACTH, placing the defect in these adrenals beyond the ACTH receptor site. Adrenal cells from normal rats responded well to these stimuli. Adrenal cyclic AMP phosphodiesterase prepared from the tumor bearing rats appeared normal both with respect to its specific activity and inhibition profile with theophylline. Exposure of the MtTF4 adrenal cells to 1,2-3H-cholesterol in the presence of either cyclic AMP or ACTH did not result in an increase in radioactively labeled corticosterone, whereas increased label could be demonstrated in adrenal cells from normal rats similarly treated.
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PMID:Lack of steroidogenic response to cyclic AMP and ACTH in adrenal cells from rats bearing the MtTF4 tumor. 17 38

Urinary excretions of free cortisol and corticosteroid sulfates were determined in 31 female controls, 77 breast cancer patients, 14 cases of colonic cancer, and 7 patients with bronchial carcinoma. Elevated corticosteroid sulfate excretion was present in 38% of patients with locally recurrent breast cancer and 30% of those with distant metastases, but in only 13% of the "early" breast cancer cases. A similar abnormality was seen in colonic cancer. Urinary free cortisol was usually normal. ACTH stimulation in a normal subject produced marked increases of both urinary free cortisol and corticosteroid sulfates. It is concluded that elevated corticosteroid sulfate excretion in cancer patients arises from an increased cortisol production rate combined with increased sulfurylation of the steroid. In bronchial carcinoma patients, changes similar to those occurring in the ACTH-treated normal subject may have resulted from ectopic ACTH production in the tumor.
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PMID:The urinary excretion of corticosteroid sulfates by cancer patients. 17 59


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