Differential effects of parathyroid hormone responsive cultured human cells on biological activity of parathyroid hormone and parathyroid hormone inhibitory analogues.

We have employed parathyroid hormone (PTH) responsive human cells cultured from dermis or giant cell tumors of bone (GT) to evaluate the biological properties of a newly developed in vivo PTH inhibitor, [Tyr34]bPTH-(7-34)-amide (PTH-Inh). Short periods of incubation of cells from dermis or GT with maximal stimulatory concentrations of PTH in the presence of increasing concentrations of PTH-Inh resulted in a dose-dependent inhibition of the adenosine cyclic 3',5'-phosphate (cAMP) response (Ki = 3 X 10(-7) M and 4.2 X 10(-7) M for GT and dermal cells, respectively).

An in vitro clonal assay of adherent stem cells (ASC) in mouse marrow.

Hematopoietic stem cells with high proliferative capacity can be assayed when stromal bone marrow cultures are overlaid with limiting dilutions of marrow samples. This leads to hematopoietic growth after 4 weeks in a fraction of cultures, consistent with expectations based on Poisson statistics. It will be shown that monoclonal cultures are obtained that last from 2 to 15 weeks and that can generate up to several million mature granulocytes.

Evaluation of the biological properties of parathyroid hormone and analogues in a vascularly isolated parotid gland-based assay.

Infusion of bovine parathyroid hormone (bPTH) preparations into the arterial blood supply of the vascularly isolated parotid gland in anaesthetized sheep increases salivary phosphate concentration and gland blood flow rate with rapid onset and offset of action. These responses have been used as a bioassay for PTH and PTH analogues and for assessing the properties of an in-vitro inhibitory analogue [Nle-8, Nle-18, Tyr-34]bPTH-(3-34)amide. [Nle-8, Nle-18, Tyr-34]bPTH-(1-34)amide at 10(-9) to 10(-8) mol/l was four to five times more potent than bPTH(1-34) on both salivary phosphate and blood flow assays.

Photoaffinity labeling of parathyroid hormone receptors: comparison of receptors across species and target tissues and after desensitization to hormone.

Cells derived from human giant cell tumors of bone and fibroblasts derived from human neonatal foreskin respond to parathyroid hormone (PTH) by increasing the intracellular and extracellular levels of adenosine cyclic 3',5'-phosphate (cAMP). Using photoaffinity labeling methods, we examined these cells for the presence of a PTH receptor or a binding subunit of a receptor complex. A previously designed biologically active and photolabile radioligand analogue of PTH was reacted with these intact cells.

Difference between 1-84 parathyroid hormone and the 1-34 fragment on renal tubular calcium transport in the dog.

Acute clearance studies were performed in chronically thyroparathyroidectomized dogs to determine similarities and differences between the effects of 1-34 and 1-84 parathyroid hormone (PTH) on urinary calcium excretion. In a small (physiological) dose, 1-84 PTH caused no mean change in percentage calcium excretion, while the 1-34 fragment was frankly calciuric. At this dose, the two hormone preparations were equally phosphaturic.

Corticosteroidogenesis and adenosine 3', 5'- monophosphate production by the amino-terminal (1-34) fragment of human parathyroid hormone in rat adrenocortical cells.

Several studies have revealed a variety of interactions between PTH and ACTH. The existence of a significant area of homology in the bioactive regions of the two molecules has been proposed as a possible reason for such interactions. To clarify the relationship, corticosteroidogenic and cAMP accumulative effects of bovine PTH (bPTH 1-84), its amino-terminal fragment (bPTH 1-34), and the amino terminal fragment of human PTH (hPTH 1-34) were compared with ACTH 1-39 by determining their dose-response characteristics in collagenase-dissociated adrenocortical cells from rats.

Semi-preparative high-performance liquid chromatographic purification of a 28-amino acid synthetic parathyroid hormone antagonist.

Structure-activity studies of parathyroid hormone (PTH) over the last decade have led to the design and synthesis of a peptide hormone inhibitor of PTH action in vivo, [Tyr-34]bPTH-(7-34)amide. To evaluate the biological properties of this 28-amino acid hormone analogue, sufficient amounts of the peptide needed to be prepared in a high state of purity to permit continuous infusion in groups of animals for periods of several hours. For this purpose, gel chromatography followed by semi-preparative, reversed-phase high-performance liquid chromatography (HPLC) using a lyophilizable solvent gradient system of acetonitrile in 0.

A multiresponse parathyroid hormone assay: an inhibitor has agonist properties in vivo.

Vitamin D-deficient rats subjected to thyroparathyroidectomy (TPTX) were used to evaluate in vivo the biological properties of native bovine parathyroid hormone (bPTH) and chemically synthesized fragments and analogues of the hormone on several parameters of hormone action: calcium and phosphorus fluxes, generation of cyclic adenosine 3',5'-monophosphate (cAMP), and the metabolism of 25-hydroxyvitamin D3 [25(OH)D3]. Vitamin D-deficient rats, after TPTX or sham operation, were intravenously infused with a nutrient containing 7.5 mM CaCl2 for 30 h.

A parathyroid hormone inhibitor in vivo: design and biological evaluation of a hormone analog.

A synthetic analog of bovine parathyroid hormone (bPTH), [tyrosine-34] bPTH-(7-34)NH2, was found to inhibit parathyroid hormone action in vivo. When the analog and parathyroid hormone were infused simultaneously to rats at a molar ratio of 200 to 1, the analog inhibited the excretion of urinary phosphate and adenosine 3',5'-monophosphate. When infused alone at the same dose rate, the analog was devoid of agonist activity.

Dynamics of cortisol and endorphin responses to graded doses of synthetic ovine CRF in sheep.

Corticotropin-releasing factor (CRF), recently isolated from sheep hypothalami, has been shown to stimulate secretion of ACTH and beta-endorphin in vitro, and in vivo in rat and man. In previous reports, responses to ovine CRF were studied in heterologous bioassay systems where the ovine sequence was likely to act as a CRF analogue. We administered synthetic ovine CRF to sheep to assess the dynamics of endorphin and cortisol responses.

Prosomatostatin-specific antigen in rat brain: localization by immunocytochemical staining with an antiserum to a synthetic sequence of preprosomatostatin.

Using an antiserum to a 15-amino acid synthetic peptide corresponding to amino acids 63-77 of rat preprosomatostatin (rat somatostatin cryptic peptide, RSCP), we have compared the distribution of immunoreactive RSCP (IR-RSCP) with that of immunoreactive somatostatin-14 in the rat brain. IR-RSCP was present in neuronal cell bodies, processes, and axon terminals in the hypothalamic tuberoinfundibular system as well as in diverse regions of the central nervous system in an identical distribution to immunoreactive somatostatin. These observations indicate that in neurons the somatostatin prohormone or the NH2-terminal extension peptide of somatostatin-28 (or both) is stored and transported intracellularly along with somatostatin 14.

Parathyroid hormone: effects of the 3-34 fragment in vivo and vitro.

The biologically active fragment ofparathyroid hormone, consisting of residues 1-34, and its in vitro antagonist, fragment 3-34, were administered separately or in combination to chronically thyroparathyroidectomized dogs. These fragments were also studied in vitro with dog renal cortical membranes. Fragment 3-34 inhibited the stimulation of adenylate cyclase by fragment 1-34 in vitro, but had no agonist or antagonistic effects on renal phosphate transport in vivo.

Endotoxin-stimulated opioid peptide secretion: two secretory pools and feedback control in vivo.

Small doses of endotoxin evoked a dramatic biphasic response of opioid peptide secretion into blood in sheep. The first phase began within minutes and coincided with a brief hypertensive response to endotoxin well before the appearance of fever or hypotension. The ratio of beta-endorphin to beta-lipotropin fell abruptly at the onset of the second phase of release, suggesting early depletion of a pool rich in beta-endorphin and subsequent emergence of a pool rich in unprocessed precursor.

Retreatment of retinoblastoma with external beam irradiation.

A retrospective review of cases on file at the Ophthalmic Oncology Center of New York Hospital-Cornell Medical Center, New York, was undertaken to examine the effectiveness of a second course of radiotherapy on retinoblastoma. One hundred four patients were found to have been treated with at least two courses of external beam irradiation to one eye. All but one of the cases were bilateral, the other eye with more advanced disease having been previously enucleated.

In vitro studies on an antagonist of parathyroid hormone [Nle-8, Nle-18, Tyr-34]bPTH-(3-34)amide.

1 The actions of parathyroid hormone (PTH) are antagonized in vitro by the peptide [Nle-8, Nle-18, Tyr-34]-bPTH-(3-34)amide, an analogue of PTH. In this paper, the actions of the inhibitory peptide were investigated in vivo. 2 Native parathyroid hormone (bPTH-(1-84)), administered i.

Proliferative capacity of murine hematopoietic stem cells in vitro.

Large numbers of granulocytes can be collected repeatedly from the supernatant medium of long-term cultures of mouse bone marrow cells. A constant relationship was found between the number of adherent hematopoietic stem cells and the lifetime cell production per culture. The data indicate that there is a limit to the proliferative capacity of normal and of irradiated stem cells.