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Biomedical subjects

D N Orth

Publications and source records attributed to D N Orth.

At least 145 records · Page 8Linked to original sources
PubMed1978

Diurnal rhythm and disappearance half-time of endogenous plasma immunoreactive beta-MSH (LPH) and ACTH in man.

In order first to establish the disappearance t 1/2 of endogenous immunoreactive human beta-MSH (RIA-h beta MSH), which is now known to represent the lipotropins, human beta-LPH and human gamma-LPH, the plasma concentrations of RIA-h beta MSH, RIA-hACTH, and fluorogenic corticosteroids (cortisol) were measured before and during infusion of cortisol in three patients with primary adrenocortical insufficiency from whom steroid replacement had been withdrawn. The t 1/2 for RIA-h beta MSH ranged from 44-133 min (mean, 83), and for RIA-hACTH ranged from 20-51 min (mean, 40). On this basis, 30-min sampling intervals were chosen to measure plasma concentrations of RIA-h beta MSH, RIA-hACTH, and cortisol in three normal subjects for 24 h. Similar diurnal rhythms were observed for all three hormones. Highest values (58.0 +/- 5.8 pg/ml) for RIA-h beta MSH were observed at about the time of awaking and lowest values (15.0 +/- 2.1 pg/ml) shortly after retiring. The secretion of both RIA-h beta MSH and RIA-hACTH appeared to be episodic, with about 8-10 secretory episodes/24 h, and the timing of their secretory episodes appeared to be nearly identical. There was excellent correlation (P less than 0.001) between simultaneous concentrations of RIA-h beta MSH and RIA-hACTH in all three subjects. These results establish the presence of a diurnal rhythm in plasma lipotropins (RIA-h beta MSH) and suggest that roughly equimolar amounts of ACTH and LPH are secreted simultaneously by the pituitary under basal conditions in man.

Adrenocorticotropic Hormone↗
PubMed1978

Homologous radioimmunoassay for human epidermal growth factor (urogastrone).

Epidermal growth factor (EGF), a polypeptide hormone originally discovered in the mouse submaxillary gland, stimulates growth in a variety of tissues in several species. This hormone has recently been identified in human urine. A homologous RIA for human EGF (RIA-hEGF) has been developed. In general, levels were similar to those recently reported using a heterologous RIA system. Twenty-four-hour urinary excretion of RIA-hEGF by normal adult males and females was 63.0 +/- 3.0 and 52.0 +/- 3.5 (mean +/- SE) micrograms/total vol, or 29.7 +/- 1.1 and 39.8 +/- 1.7 micrograms/g creatinine, respectively. Excretion by females taking oral contraceptives was significantly greater (60.1 +/- 2.7 micrograms/g creatinine; P less than 0.01) than that by females who were not. Recent evidence suggests the probable identity of hEGF and beta-urogastrone, a potent inhibitor of gastric acid secretion. Adult males with active peptic ulcer disease appeared to have lower urinary RIA-hEGF excretion (22.9 +/- 2.6 micrograms/g creatinine) than normal men, but this was not significant (P greater than 0.05). Several of those with very low values had histories of alcohol abuse. Excretion by patients with Cushing's syndrome was normal. Patients with psoriasis or recovering from major burns excreted both abnormally high and abnormally low levels of RIA-hEGF, with no obvious correlation to their clinical condition. There was no apparent diurnal or postprandial variation in urinary RIA-hEGF excretion by normal subjects. An excellent linear correlation was observed between RIA-hEGF and creatinine concentrations in each urine sample for each subject, suggesting that RIA-hEGF concentration in a random urine sample provides a valid index of 24-h RIA-hEGF excretion.

Adult↗
PubMed1978

Isolated deficiency of adrenocorticotropin (ACTH) and lipotropins (LPHs).

A patient with hypoadrenocorticism was found to have low basal plasma concentrations of ACTH and lipotropins and deficient responses of these hormones to insulin-induced hypoglycemia and lysine vasopressin. The adequacy of secretion of other anterior pituitary hormones was assessed either directly, by measuring their concentration in plasma, or indirectly, by assessing end organ function, under basal and stimulated conditions. The responses of gonadotropins to LRH and of PRL and TSH to TRH were normal. The etiology of this rare condition of isolated deficiency of ACTH and lipotropins remains to be elucidated.

17-Ketosteroids↗
PubMed1978

ACTH-secreting medullary carcinoma of the thyroid presenting a severe idiopathic osteoporosis and senile purpura: report of a case and review of the literature.

A 64-yr-old female presented with severe osteoporosis and easy bruisability of over 2-yr duration. Biopsy of a neck mass revealed medullary carcinoma of the thyroid. Subsequently, lymphangitic pulmonary metastases were demonstrated which had been present radiographically for at least 4 yr. Basal serum calcitonin was markedly elevated and increased during calcium infusion. The diagnosis of ectopic ACTH syndrome was first entertained when hypokalemic alkalosis was observed during evaluation of her carcinoma. Elevated urinary 17-hydroxycorticosteroids, 17-ketosteroids, plasma cortisol, and immunoreactive plasma ACTH levels were documented. Adrenal steroidogenesis seemed to suppress on high dose dexamethasone. The primary tumor and its metastases contained high concentrations of immunoreactive ACTH and beta-melanocyte-stimulating hormone. Hepatic metastases contained extremely high concentrations of calcitonin. In contrast to the usual presentation of the ectopic ACTH syndrome as primarily hypokalemic alkalosis and glucose intolerance, patients with relatively benign and indolent ACTH-secreting tumors, such as certain cases of medullary carcinoma of the thyroid, may present with more typical signs and symptoms of Cushing's syndrome. The more pronounced cushingoid features in this latter group presumably reflects a more prolonged period of exposure to elevated glucocorticoid levels. Ten cases of ACTH-secreting medullary carcinoma of the thyroid from the literature are discussed. Extopic ACTH production by such tumors should be considered in the evaluation of patients with Cushing's syndrome or unexplained severe osteopenia.

Adrenocorticotropic Hormone↗
PubMed1978

Ectopic production of high molecular weight calcitonin and corticotropin by human small cell carcinoma cells in tissue culture: evidence for separate precursors.

The DMS-79 continuous line of human small cell lung carcinoma cells, which produces immunoreactive (IR)-corticotropin (ACTH), -lipotropin (LPH), and -beta-endorphin (beta END), was found to produce IR-calcitonin (CT). Two major high molecular weight (HMW) forms of IR-CT were observed after gel exclusion chromatography under denaturing conditions (mol wt. approximately 7,000 and approximately 14,000), as well as a minor HMW IR-CT component (mol. wt. approximately 70,000). None of these IR-CT materials was extracted from DMS-79 medium by affinity chromatography using an ACTH antibody covalently bound to agarose. These results demonstrate ectopic production of HMW forms of CT and ACTH/LPH/beta END by human lung tumor cells in tissue culture, but do not support the existence of a common CT/ACTH/LPH/beta END precursor molecule.

Adrenocorticotropic Hormone↗
PubMed1978

The detection of "purified" incubation damage by several radioimmunoassay separation methods.

Damage to labeled peptides has been recognized as an almost unavoidable consequence of exposure to plasma during radioimmunoassay incubat ions, which can cause serious errors in estimating plasma hormone concentrations. Surprisingly little is known about the nature and behavior of damaged labeled peptides in various systems for separating antibody-bound from free labeled hormones. This is due in part to lack of a generally applicable definition of "incubation damage" as an altered molecule rather than a phenomenon observed in the separation system. We have proposed the definition, "nonimmunoreactive radioactive peptide(s) produced during incubation of radioactively labeled peptide antigens." With 125I-hbetaMSH used as a model labeled peptide antigen, incubation damage was produced under defined conditions and purified by gel filtration. It appeared smaller than 125I-hbetaMSH, suggesting that it resulted from enzymic proteolysis. The behavior of purified incubation damage in five representative separation systems was not consistently predictable. In the paper chromatoelectrophoresis and QUSO-plasma systems, it behaved like a large molecule, partitioning in the "bound" phase. In these two systems, incubation damage must be detected in appropriate control tubes containing the specimen without antibody. In the dextran-charcoal, polyethylene glycol, and second-antibody systems, damage behaved like a small nonimmunoreactive peptide and partitioned in the "free" phase. In these systems, since incubation damage cannot be separated from free 125I-labeled peptide, damage control tubes must have excess antibody added after incubation. The apparent lack of incubation damage in some radioimmunoassays may be due to inappropriate controls for its detection, leading to erroneous estimation of plasma hormone concentrations.

Charcoal↗
PubMed1977

Results of treating childhood Cushing's disease with pituitary irradiation.

To determine the usefulness of conventional pituitary irradiation in childhood Cushing's disease, we reviewed the results of this treatment in 15 patients. Twelve were cured (mean plasma cortisol of less than 10 microgram per deciliter and 24-hour urinary 17-hydroxycorticosteroid excretion of less than 7 mg per gram of creatinine) within 18 months, and 10 of the 15 were cured within nine months. Three failures required bilateral adrenalectomy. Growth resumed in 12, with adult heights of 156 to 166 cm. Sexual development proceeded normally in all 15, with normal secondary sexual characteristics and sexual function, and demonstrated fertility in four married adults. Intellectual function appeared normal. Basal and stimulated hormone levels were normal, except for subnormal (5 ng per milliliter or less) growth hormone levels after hypoglycemia in one of 12 patients. There were no complications of therapy and no progressive pituitary enlargement or hyperpigmentation. Pituitary irradiation is safe and effective therapy for childhood Cushing's disease.

17-Hydroxycorticosteroids↗
PubMed1977

The effect of cell membrane alteration on glucocorticoid uptake by the AtT-20/D-1 target cell.

The glucocorticoid-sensitive AtT-20/D-1 cell line was used to study cellular uptake of glucocorticoids. A previous observation that glucocorticoid uptake by these cells was temperature dependent had prompted us to postulate that glucocorticoids entered the cell by a temperature-sensitive transport process located in the cell membrane. Attempts were then made to perturb the membrane mechanism. In some of these experiments, intact cells were treated with neuraminidase or pronase. The release of sialic acid in the case of neuraminidase treatment and of sialic acid and cell surface peptides in the case of pronase treatment demonstrated that the enzymes were effective. Approx. 60% of total cellular sialic acid was released by a 15 min incubation with 20 microng/ml neuraminidase at 25 degrees C. The treated cells appeared to be viable, in that they continued to produce corticotropin at a normal rate, yet intact cell glucocorticoid binding at both 4 and 25 degrees C was only 20-30% of that of untreated cells. Treatment with pronase also caused steroid uptake at 4 and 25 degrees C to be reduced, although the extent of reduction was less than that seen following neuraminidase treatment. In other experiments, the effect of exposure of AtT-20/D-1 cells to ethanol or dimethyl sulfoxide was determined. The solvent concentrations used (0.5-10%) did not alter cell viability significantly, and the ability of the cytosol receptor to bind steroid in a cell-free preparation was unimpaired. However, incubation of intact cells with 10% (v/v) dimethyl sulfoxide or ethanol resulted in an 80-90% decrease in steroid uptake at 25 degrees C. We conclude that steroid uptake by the intact cell can be perturbed by treatments which do not affect the cytosol receptor or alter cell viability. These results support the postulate that glucocorticoids enter the AtT-20/D-1 cell by a specific membrane-associated mechanism.

Animals↗
PubMed1977

Ectopic production of antidiuretic hormone (adh), adrenocorticotrophic hormone (ACTH) and beta-melanocyte stimulating hormone (beta-MSH) by an oat cell carcinoma of the lung.

A 61 year old woman presented with profound hyponatremia and markedly low serum osmolality. Urine osmolality was greater than the serum osmolality, an abnormality that was corrected by water restriction, suggesting inappropriate ADH secretion. Although there were no physical signs of Cushing's syndrome, her serum potassium level was low and markedly elevated levels of plasma and urine corticosteroids were not altered by the administration of large amounts of dexamethasone, suggesting the ectopic ACTH-MSH syndrome. Plasma levels of immunoreactive ACTH and beta-MSH were elevated. At autopsy, a metastastic oat cell carcinoma of the lung, not detected antemortem by chest roentgenograms and bronchoscopy, was found. Immunoreactive ADH, ACTH and beta-MSH were detected in the primary tumor and in metastases to the liver. beta-MSH was also detected in the spleen, in which metastases were observed. This is the first documented case of the simultaneous production of ADH, ACTH and beta-MSH by neoplastic tissue associated with clinical manifestations of the syndrome of inappropriate ADH secretion and the ectopic ACTH-MSH syndrome.

Adrenocorticotropic Hormone↗
PubMed1977

Tissue-specific stimulation of ornithine decarboxylase activity by pituitary factors immunologically related to growth hormone.

Ornithine decarboxylase (L-ornithine carboxylase, EC 4.1.1.17) is an important enzyme in polyamine synthesis. Its activity is influenced by several peptides hormones, including growth hormones, which have physiological significance in various growth situations. A crude ovine pituitary growth hormone preparation (NIH-GH-S10) was subjected to gel exclusion chromatography (Sephadex G-100) and two major fractions were obtained. One of these corresponded to dimeric growth hormone (GH). The other fraction was excluded by the gel matrix, suggesting a material of higher molecular weight than GH. This was confirmed by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Analysis of a high molecular weight fraction by radioimmunoassay (antisera prepared against GH) and by bioassay (weight gain in hypophysectomized rats) gave apparent GH contents of 19% and 6%, respectively. On a weight basis, the high molecular weight fraction was more effective than GH in stimulating the activity of hepatic and adrenal ornithine decarboxylase, but GH was more effective in stimulating renal ornithine decarboxylase activity. Subfractionation of the high molecular weight fraction using a high porosity gel (Sephadex G-200) gave four fractions, which were shown by amino acid analysis and by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate to be distinct from GH and heterogenous. These subfractions had different potencies for stimulating renal and hepatic ornithine decarboxylase activity. The ability of crude growth hormone preparations to stimulate ornithine decarboxylase activity in some tissues may be a function of pituitary factors, in addition to GH, which have minimal growth promoting activity.

Adrenal Glands↗
PubMed1977

High molecular weight forms of human ACTH are glycoproteins.

The RIA-ACTH in a normal human pituitary, 2 ectopic ACTH-secreting tumors and plasma from a patient with Nelson's syndrome and one with ectopic ACTH syndrome was divided into 3 molecular weight classes after gel exclusion chromatography. The largest component appeared in or near the void volume and was designated "big" RIA-ACTH. The second, designated "intermediate" RIA-ACTH, eluted between the void volume and standard human 1-39 ACTH (mol. wt. 4,541). An immunoreactive material designated "little" ACTH-coeluted with standard human ACTH. A significant fraction (29-61%) of "big" RIA-ACTH from the tumors bound to concanavalin A-agarose and was eluted with 0.2 M alpha-methyl-D-mannopyranoside. An additional 16-22% of "big" RIA-ACTH was more tightly bound to the concanavalin A, but could be purged from the column with 0.1 M acetic acid. A smaller total percent of "big" RIA-ACTH from the pituitary (20%) and plasmas (5-10%) bound to the lectin and was similarly eluted and purged. Relatively little (less than 8%) of "intermediate" RIA-ACTH from all sources bound to concanavalin A, with the exception of that in the pitull sources was essentially excluded (greater than 93%) from the column. These data indicate that a significant fraction of human "big" RIA-ACTH is a glycoprotein and that human "intermediate" RIA-ACTH may be also.

Adenoma, Islet Cell↗
PubMed1976

Multiple glucocorticoid binding components of intact AtT-20/D-1 mouse pituitary tumor cells.

Glucocorticoids were found to bind to two components in the AtT-20/D-1 pituitary tumor cell. One component was characterized by slow dissociation of the bound steroid, stringent glucocorticoid specificity and high steroid binding affinity (Kd = 4.64 - 10(-9) M for triamcinolone acetonide). Thus, the characteristics of this component, termed the slowly dissociable component, resembled those of the soluble cytosol receptor. The other component exhbited lower binding affinity (Kd = 1.57 - 10(-7) M for triamcinolone acetonide), less stringent glucocorticoid specificity, and very rapid dissociation of bound, labelled glucocorticoid, Binding to this component, termed the rapidly dissociable component, represented 60% of total steroid binding to intact cells at 4 degrees C. Incubation of intact cells at 25 degrees C caused a progressive increase in steroid binding to the slowly dissociable component with no change in the absolute amount of ste roidal binding to the rapidly dissociable component. The high-binding affinity and preference for glucocorticoids shown by both components favor their function as biologically significant mediators of steroid action in this glucocorticoid responsive cell.

Adenocarcinoma↗
PubMed1976

Hormonal regulation of renal ornithine decarboxylase activity in the rat.

The regulation of the activity of the renal enzyme ornithine decarboxylase (L-ornithine carboxy-lyase, EC 4.1.1.17) was examined in the rat. In the intact animal adapted to a light/dark cycle of 14 hours and 10 hours, respectively, the level of renal ornithine decarboxylase activity was rhythmical and paralleled the diurnal rhythm in plasma corticosteroid concentration. Renal ornithine decarboxylase activity and plasma corticosterone were highest during the early hours of darkness and lowest during the hours of light. Following hypophysectomy, the level of renal ornithine decarboxylase activity declined rapidly and remained low and without a demonstrable diurnal rhythm. When pituitary hormone levels were temporarily restored in the hypophysectomized rat by the injection of pituitary extract, renal ornithine decarboxylase activity increased rapidly, reached a peak within 8 hours, and returned toward pre-injection levels by 12 hours. Exogenous growth hormone, ACTH and cortisol each increased renal ornithine decarboxylase activity in the hypophysectomized rat, with the highest levels of activity being achieved with growth hormone. Other pituitary hormones (FSH, LH, TSH and prolactin) were ineffective. After bilateral adrenalectomy, renal ornithine decarboxylase activity retained a rhythmical pattern similar to that observed in the intact rat, but the levels were increased. Growth hormone and cortisol increased renal ornitine decarboxylase activity in the adrenalectomized-hypophysectomized animal to the same extent as in the hypophysectomized animal, but ACTH was almost totally ineffective. These data suggest that the pituitary plays a major role in the regulation of renal ornithine decarboxylase activity in the rat, primarily through the rhythmical secretion of growth hormone and ACTH.

Adrenal Cortex Hormones↗
PubMed1976

Binding of cytosol receptor-glucocorticoid complexes by isolated nuclei of glucocorticoid-responsive and nonresponsive cultured cells.

Nuclear binding of the AtT-20 cytosol receptor-glucocorticoid complex was studied in a cell-free system using nuclei from steroid-responsive (AtT-20) and nonresponsive (EPO-G1) cell lines, both of which synthesize ACTH. The AtT-20 cell line was derived from a mouse pituitary adenocarcinoma, while the EPO cell line was established from a human malignant melanoma. The nonresponsive EPO cells lacked a cytosol receptor for glucocorticoids, and, when whole cells were incubated with labeled glucocorticoid, they were unable to concentrate the steroid in their nuclei. A cell-free system using AtT-20 cytosol preincubated with labeled glucocorticoid was used to study binding by isolated nuclei. Binding to isolated nuclei from both cell lines was indistinguishable, in terms of temperature sensitivity, binding capacity, and saturability. Sucrose density gradient analyses of KCl extracts of nuclei labeled under these cell-free conditions showed 3.2-3.6 S peaks. In contrast, a 4.0 S peak was observed consistently when unreacted cytosol was analyzed on high-salt gradients, suggesting that interaction with nuclei from both cell lines caused the receptor to alter its sedimentation characteristics. These findings suggest either that all cells contain nuclear acceptor sites and that target cell responsiveness is conferred solely by the presence or absence of the cytosol receptor, or that binding sites detected in isolated nuclei may be different from those observed in intact cells and may, in fact, obscure them.

Animals↗
PubMed1976

Method for preparation of ampoules containing microgram quantities of polypeptide hormones for distribution and use as laboratory standards: synthetic human ACTH and beta-MSH.

There are a number of polypeptide hormones, their subunits, and other derivatives that are available in such short supply as to preclude distribution by conventional methods to the many qualified investigators who require them. This report describes a method for preparing sealed ampoules of two such hormones, the utilization of which can provide many qualified investigators with comparable, stable reference compounds for several years and eliminate unnecessary waste and error associated with the distribution and use of bulk quantitites of peptide hormone preparations. Sealed ampoules of synthetic human adrenocorticotrophic hormone (alpha(h)(1-39) ACTH) and beta melanocyte-stimulating hormone (beta(h)(1-22) MSH) were prepared. Each ampuole contains 50 mug of dried and recoverable peptide plus 1 mg of lactose, sealed under dry nitrogen at atmospheric pressure. The respective preparations are fully active, both biologically and radioimmunologically, and are suitable as reference compounds in all types of biologic and radioimmunologic assays of these hormones. In addition, radioactive iodine labeling of each peptide can be accomplished without prior removal of the lactose.

Adrenocorticotropic Hormone↗