Measurement of 1,25-dihydroxyvitamin D3 receptors in breast cancer and their relationship to biochemical and clinical indices.

Both normal and malignant breast tissue contain the specific receptor for 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3). A recent study has shown its presence in 80% of surgically removed breast tumors, although only at low levels. We have measured the 1,25-(OH)2D3 receptor in breast tumors from 68 patients and have found it at similar frequency (75%) but at much higher concentrations (range, less than 1 to 30 fmol/mg protein).

Specific binding of 1,25 dihydroxyvitamin D3 in lymphocytes.

We examined ten cellular or tissue sources of lymphocytes for specific binding of 1,25(OH)2D3, the hormonally active form of vitamin D3. A specific-binding protein was found in three of these sources. Scatchard analysis of cytosol from a follicular lymphoma cell line revealed binding sites with a Kd of 7.

Essential steps in the measurement of normal circulating levels of calcitonin.

Before interpreting the results of assays which claim to measure circulating levels, one must have full data on the sensitivity, the reproducibility and specificity of the methods and antisera used. Without this information figures are meaningless and may be regarded as fiction rather than science. Secondly, and of equal importance, one must have full details of those physiological and pharmacological factors which are known to affect the circulating levels.

[Are Stannius corpuscles the parathyroid glands of teleost fishes? Ultrastructural, cytologic and immunocytochemical arguments].

Parathyrin of Stannius corpuscles (PCS), glands which are restricted to Holostei and Teleostei, is closely related to mammalian parathyrin (PTH) secreted by the parathyroids [( 6] to [9]). In unstimulated and stimulated CS we have shown the same structure and cellular types that are described in mammalian parathyroids. We observed three types of cells; the two sorts of cells already described [14] present such a difference of density (Fig.

Regulation of calcium-regulating hormones by exogenous sex steroids in early postmenopause.

A major function of calcitonin in humans appears to be maintenance of the skeleton. There is a marked sex difference in circulating calcitonin levels: women have much lower levels. This has led to speculation that calcitonin lack may be one factor involved in the pathogenesis of postmenopausal bone loss.

Immunocytochemical localisation of katacalcin, a calcium-lowering hormone cleaved from the human calcitonin precursor.

Katacalcin is a newly discovered calcium-lowering hormone predicted from the nucleotide sequence of a cloned cDNA derived from human calcitonin mRNA. The aim of the study was to localise katacalcin by immunocytochemistry at both light and electron microscope levels. Antisera to synthetic katacalcin and calcitonin were used to investigate 8 cases of medullary thyroid carcinoma and 6 normal human thyroids (3 adult and 3 fetal).

Two distinct insulins in the guinea pig: the broad relevance of these findings to evolution of peptide hormones.

In this paper we use the published data of others as well as our own recent data to question the widespread assumption that the gene for guinea pig insulin mutated rapidly after the divergence of guinea pigs from the main line of rodent evolution. We suggest that instead guinea pigs may have two pairs of alleles, one for typical guinea pig insulin, which is expressed in its pancreatic beta cells, and the other for a more typical mammalian insulin (designated rat/pork-type insulin), which is expressed in extrapancreatic cells. Further, we suggest the possibility that both pairs of genes may be evolutionarily very ancient and highly conserved.

Katacalcin: a new plasma calcium-lowering hormone.

A second potent plasma calcium-lowering peptide, katacalcin (PDN-21), flanks calcitonin within the human calcitonin precursor. Plasma katacalcin was present in 57 healthy volunteers. Concentrations were higher in males than in females and approximately equimolar with calcitonin.

Immunoreactive calcitonin production by a human promyelocytic leukemia cell line HL60.

Using a sensitive radioimmunoassay, we detected human immunoreactive calcitonin in cell extracts and in cell-exposed media of the HL60 cell line derived originally from a patient with acute promyelocytic leukemia. The cell extract was chromatographed on a reverse-phase high-pressure liquid chromatography system. Radioimmunoassay of the fractions showed that the immunoreactive calcitonin was heterogeneous but had peaks corresponding to those of synthetic human calcitonin monomer and its sulphoxide.

Salmon calcitonin in lizard brain: a possible neuroendocrine transmitter.

Calcitonin is a polypeptide which until recently was thought to be concerned primarily with the control of body calcium. Recent studies carried out with radioimmunoassay have demonstrated the presence of this peptide in brain and we have carried out an immunohistochemical study showing the presence of high concentrations of calcitonin in the nerve varicosities and terminals of the hypothalamus and in particular the median eminence of the lizard Lacertus muralis. The distribution of this calcitonin, which cross-reacted with anti-salmon calcitonin, suggests that this polypeptide and/or its flanking peptides may function as a neuroendocrine neurotransmitter.

Effect of rifampicin and isoniazid on vitamin D metabolism.

Rifampicin, 600 mg, and isoniazid, 300 mg daily for 14 days, reduced circulating levels of 25-hydroxy vitamin D (25-OHD) and 1 alpha, 25-dihydroxy vitamin D (1,25(OH)2D) by 34% (P less than 0.01) and 23% (P less than 0.05) in eight healthy subjects.

Role of prolactin in vitamin D metabolism and calcium absorption during lactation in the rat.

Intestinal calcium absorption and plasma levels of 1,25-dihydroxycholecalciferol (1,25(OH)2D3) were measured in lactating and non-lacting rats and the effects of bromocriptine and exogenous prolactin treatment were evaluated. In lacting rats calcium absorption and plasma levels of parathyroid hormone, 1,25(OH)2D3 and alkaline phosphatase activity were significantly increased. Bromocriptine treatment significantly reduced the enhanced calcium absorption and levels of plasma 1,25(OH)2D3 and alkaline phosphatase but had no significant effect on plasma levels of parathyroid hormone.

Specific binding of 1,25-dihydroxycholecalciferol in human medullary thyroid carcinoma.

A specific 1,25-dihydroxycholecalciferol-binding protein has been detected in high-salt cytosols prepared from human medullary thyroid carcinomas. The binding protein had the same equilibrium dissociation constant (Kd = 0.17 +/- 0.

Further evidence for calcitonin gene duplication: the identification of two different calcitonins in a fish, a reptile and two mammals.

In order to investigate the possibility of the simultaneous expression of two different calcitonin genes during evolution, we studied the nature of calcitonin in: eel pericardium, salamander branchial region, rat thyroid, ox thyroid, medullary carcinoma of the human thyroid and human thyrotoxic goitre. Sensitive and specific RIAs for human calcitonin (hCT) and salmon calcitonin (sCT) were used in combination with high pressure liquid chromatography (HPLC). We found that two different immunoreactive calcitonins resembling hCT and sCT exist in eels, salamanders and rats.

Bombesin: action on gut hormones and calcium in man.

Bombesin, a peptide with widespread biological actions, has been demonstrated in human tissues by immunological methods. To investigate its effect in man, synthetic bombesin was infused at low doses in six male volunteers. Bombesin at 2.

Identification of both human and salmon calcitonin-like molecules in birds suggesting the existence of two calcitonin genes.

To investigate whether human calcitonin (hCT) is preserved during the evolution of vertebrates, we studied extracts of avian (pigeon and chicken) thyroid and ultimobranchial glands (UBG) which have previously been reported to contain salmon calcitonin (sCT)- like molecules. A sensitive and specific radioimmunoassay for hCT, employing two antisera reacting with different regions of the molecule, was used in combination with high performance liquid chromatography (HPLC). We found that extracts of thyroid and UBG from pigeons and chickens contain, in addition to an immunoreactive sCT-like molecule (which is the major immunoreactive form), an hCT-like molecule comprising from 0.

[Immunocytochemical detection in Stannius corpuscles of the eel (Anguilla anguilla L.) of a hormone similar to the mammalian parathyroid hormone].

In eels the parathyrin of the corpuscles of Stannius (PCS), mammalian parathyroid-like hormone, has been localized in the cytoplasm of all the cells in the corpuscles. This detection was done by indirect immunofluorescence with an antiserum anti 1-84 bovine parathormone. The specificity of the reaction was demonstrated by inhibition of the coloration obtained with the 1-84 bovine parathormone and the active fragment 1-34 of human parathormone.

The construction and partial characterization of plasmids containing complementary DNA sequences to human calcitonin precursor polyprotein.

(1) Total poly(A)-containing RNA isolated from human thyroid medullary carcinoma tissue was shown to direct the synthesis in the wheat germ cell-free system of a major (Mr 21000) and several minor forms of human calcitonin precursor polyproteins. Evidence for processing of these precursor(s) by the wheat germ cell-free system is also presented. (2) A small complementary DNA (cDNA) plasmid library has been constructed in the PstI site of the plasmid pAT153, using total human thyroid medullary carcinoma poly(A)-containing RNA as the starting material.