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

1983 ◽  
Vol 244 (6) ◽  
pp. E589-E595
Author(s):  
N. Horiuchi ◽  
M. Rosenblatt ◽  
H. T. Keutmann ◽  
J. T. Potts ◽  
M. F. Holick
Keyword(s):  
Vitamin D ◽  
Parathyroid Hormone ◽  
Biological Effects ◽  
Biological Properties ◽  
Sham Operation ◽  
Plasma Phosphate ◽  
Dihydroxyvitamin D3 ◽  
Dose Dependent

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. During the last 7 h, PTH or one of its analogues was infused intravenously at rates between 0.04 and 20 nmol/h. One hour after the start of the peptide infusion, tritiated 25(OH)D3 was injected. Urine was collected hourly for phosphate and cAMP determinations and, at the end of the experiment, blood was obtained to determine the relative accumulation of tritiated 1,25-dihydroxyvitamin D3 ([3H]1,25(OH)2D3). Infusion of bPTH-(1--84), bPTH-(1--34), human (h)PTH-(1--34), or [Nle8, Nle18, Tyr34]bPTH-(1--34) amide was accompanied by a comparable dose-dependent decrease in plasma phosphate and a dose-dependent increase in plasma calcium and [3H]-1,25(OH)2D3, and urinary excretion of phosphate and cAMP. An evaluation of [Nle8, Nle18, Tyr34]bPTH-(3--34) amide, a potent inhibitor of PTH action in vitro in the renal adenylate cyclase assay, revealed that the analogue possessed weak agonist properties in vivo. The analogue increased excretion of both cAMP and phosphate in the urine, decreased plasma phosphate levels, and increased the accumulation of [3H]-1,25(OH)2D3 in the plasma. This multiparameter model system should aid in the elucidation of the in vivo biological effects of PTH and its analogues.

Responsiveness of vitamin D-deficient fetal rat limb bones to parathyroid hormone in culture

1983 ◽  
Vol 244 (4) ◽  
pp. E421-E424
Author(s):  
P. H. Stern ◽  
B. P. Halloran ◽  
H. F. DeLuca ◽  
T. J. Hefley
Keyword(s):  
Vitamin D ◽  
Parathyroid Hormone ◽  
Additive Model ◽  
Vitamin D Status ◽  
Dihydroxyvitamin D3 ◽  
Limb Bones ◽  
Fetal Rat ◽  
Fetal Rats

Radii and ulnae from 19-day fetal rats from normal or vitamin D-deficient mothers were treated with 25-hydroxyvitamin D3, 1,25-dihydroxyvitamin D3, or parathyroid hormone in vitro. Both sets of bones resorbed in response to all three agents. Statistical analysis indicated a purely additive model for the effects of vitamin D status and the bone-resorbing agents, with no evidence for interaction. The results suggest that the impaired calcemic response to parathyroid hormone seen in vitamin D-deficient animals in vivo is not the result of a specific unresponsiveness of vitamin D-deficient bone to parathyroid hormone.

scholarly journals Epimers of Vitamin D: A Review

2020 ◽  
Vol 21 (2) ◽  
pp. 470 ◽  
Author(s):  
Bashar Al-Zohily ◽  
Asma Al-Menhali ◽  
Salah Gariballa ◽  
Afrozul Haq ◽  
Iltaf Shah
Keyword(s):  
Vitamin D ◽  
Biological Activity ◽  
Hydroxyl Group ◽  
Vitamin D Metabolites ◽  
Dihydroxyvitamin D3 ◽  
In Vivo Models ◽  
Vitamin D Receptors ◽  
Potential Factors

In this review, we discuss the sources, formation, metabolism, function, biological activity, and potency of C3-epimers (epimers of vitamin D). We also determine the role of epimerase in vitamin D-binding protein (DBP) and vitamin D receptors (VDR) according to different subcellular localizations. The importance of C3 epimerization and the metabolic pathway of vitamin D at the hydroxyl group have recently been recognized. Here, the hydroxyl group at the C3 position is orientated differently from the alpha to beta orientation in space. However, the details of this epimerization pathway are not yet clearly understood. Even the gene encoding for the enzyme involved in epimerization has not yet been identified. Many published research articles have illustrated the biological activity of C3 epimeric metabolites using an in vitro model, but the studies on in vivo models are substantially inadequate. The metabolic stability of 3-epi-1α,25(OH)2D3 has been demonstrated to be higher than its primary metabolites. 3-epi-1 alpha, 25 dihydroxyvitamin D3 (3-epi-1α,25(OH)2D3) is thought to have fewer calcemic effects than non-epimeric forms of vitamin D. Some researchers have observed a larger proportion of total vitamin D as C3-epimers in infants than in adults. Insufficient levels of vitamin D were found in mothers and their newborns when the epimers were not included in the measurement of vitamin D. Oral supplementation of vitamin D has also been found to potentially cause increased production of epimers in mice but not humans. Moreover, routine vitamin D blood tests for healthy adults will not be significantly affected by epimeric interference using LC–MS/MS assays. Recent genetic models also show that the genetic determinants and the potential factors of C3-epimers differ from those of non-C3-epimers.Most commercial immunoassays techniques can lead to inaccurate vitamin D results due to epimeric interference, especially in infants and pregnant women. It is also known that the LC–MS/MS technique can chromatographically separate epimeric and isobaric interference and detect vitamin D metabolites sensitively and accurately. Unfortunately, many labs around the world do not take into account the interference caused by epimers. In this review, various methods and techniques for the analysis of C3-epimers are also discussed. The authors believe that C3-epimers may have an important role to play in clinical research, and further research is warranted.

Rat renal 25-hydroxyvitamin D3 1- and 24-hydroxylases: their in vivo regulation

1984 ◽  
Vol 246 (2) ◽  
pp. E168-E173 ◽  
Author(s):  
Y. Tanaka ◽  
H. F. DeLuca
Keyword(s):  
Vitamin D ◽  
Inorganic Phosphorus ◽  
Hydroxylase Activity ◽  
Deficient Diet ◽  
Dihydroxyvitamin D3 ◽  
1,25 Dihydroxyvitamin D3 ◽  
Dietary Phosphorus ◽  
Low Calcium

The effects of thyroparathyroidectomy, parathyroid hormone, 1,25-dihydroxyvitamin D3, dietary calcium, dietary phosphorus, age, and sex on the renal 25-hydroxyvitamin D3 1- and 24-hydroxylases measured in vitro in rats have been studied. Thyroparathyroidectomy of vitamin D-deficient rats abolishes 25-hydroxyvitamin D3 1-hydroxylase activity, and administration of bovine parathyroid extract to the thyroparathyroidectomized rat restores diminished 1-hydroxylase activity. Both suppression and restoration of the enzyme activities require many hours (18-24 h) independent of rapid changes in serum calcium and inorganic phosphorus levels in response to these manipulations. Administration of 1,25-dihydroxyvitamin D3 to vitamin D-deficient rats suppresses 25-hydroxyvitamin D3 1-hydroxylase activity and stimulates 25-hydroxyvitamin D3 24-hydroxylase activity within 48 h. Rats maintained on a low-calcium or a low-phosphorus diet with a daily supplement of 20 IU vitamin D3 show high 25-hydroxyvitamin D3 1-hydroxylase activity and low 24-hydroxylase activity as compared with rats similarly treated but fed a diet containing adequate calcium or adequate phosphorus. When vitamin D-sufficient rats having suppressed renal 25-hydroxyvitamin D3 1-hydroxylase activity are placed on a low-calcium vitamin D-deficient diet for 7 days, the 1-hydroxylase activity is greatly stimulated in 6-wk-old rats but much less so in rats with advancing age.

scholarly journals Antioxidant, Anti-Inflammatory and Anti-Angiogenic Properties of Citrus lumia Juice

2020 ◽  
Vol 11 ◽  
Author(s):  
Antonella Smeriglio ◽  
Marcella Denaro ◽  
Valeria D’Angelo ◽  
Maria Paola Germanò ◽  
Domenico Trombetta
Keyword(s):  
Ascorbic Acid ◽  
Acid Content ◽  
Molecular Mechanisms ◽  
Biological Effects ◽  
Ascorbic Acid Content ◽  
Zebrafish Embryos ◽  
Anti Inflammatory ◽  
Dose Dependent

Citrus juices are a rich source of bioactive compounds with various and well-known health benefits. The aim of this study was to investigate the polyphenols and ascorbic acid content as well as to investigate the antioxidant, anti-inflammatory and anti-angiogenic properties of the juice of an ancient Mediterranean species, Citrus lumia Risso (CLJ). The antioxidant and anti-inflammatory activities were evaluated by several in vitro cell-free and cell-based assays, whereas two different in vivo models, the chick chorioallantoic membrane (CAM) and the zebrafish embryos, were used to characterize the anti-angiogenic properties. Twenty-eight polyphenols were identified by RP-LC-DAD-ESI-MS analysis (flavonoids 68.82% and phenolic acids 31.18%) with 1-caffeoyl-5-feruloylquinic acid and kaempferol 3′-rhamnoside, which represent the most abundant compounds (25.70 and 23.12%, respectively). HPLC-DAD analysis showed a high ascorbic acid content (352 mg/kg of CLJ), which contributes with polyphenols to the marked and dose-dependent antioxidant and anti-inflammatory properties observed. CLJ showed strong and dose-dependent anti-angiogenic activity as highlighted by the inhibition of blood vessel formation on CAMs and the decrease of endogenous alkaline phosphatase on zebrafish embryos. Moreover, within the concentration range tested, no dead or malformed embryos were recorded. Certainly, further studies are needed to investigate the molecular mechanisms underlying these promising biological effects, but considering the evidence of the present study, the use of CLJ as a ready-to drink safe prevention strategy for inflammatory-based diseases correlated to angiogenesis could be justified.

scholarly journals Pleiotropic Biological Effects of Dietary Phenolic Compounds and their Metabolites on Energy Metabolism, Inflammation and Aging

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 596 ◽  
Author(s):  
María del Carmen Villegas-Aguilar ◽  
Álvaro Fernández-Ochoa ◽  
María de la Luz Cádiz-Gurrea ◽  
Sandra Pimentel-Moral ◽  
Jesús Lozano-Sánchez ◽  
...  
Keyword(s):  
Energy Metabolism ◽  
Phenolic Compounds ◽  
Molecular Mechanisms ◽  
Biological Effects ◽  
Biological Properties ◽  
In Vivo Studies ◽  
Wide Range ◽  
High Prevalence

Dietary phenolic compounds are considered as bioactive compounds that have effects in different chronic disorders related to oxidative stress, inflammation process, or aging. These compounds, coming from a wide range of natural sources, have shown a pleiotropic behavior on key proteins that act as regulators. In this sense, this review aims to compile information on the effect exerted by the phenolic compounds and their metabolites on the main metabolic pathways involved in energy metabolism, inflammatory response, aging and their relationship with the biological properties reported in high prevalence chronic diseases. Numerous in vitro and in vivo studies have demonstrated their pleiotropic molecular mechanisms of action and these findings raise the possibility that phenolic compounds have a wide variety of roles in different targets.

Effects of 1,25- and 24,25-dihydroxycholecalciferol on parathyroid hormone release from human parathyroid cells in vitro

1984 ◽  
Vol 105 (3) ◽  
pp. 354-359 ◽  
Author(s):  
Claes Rudberg ◽  
Göran Åkerström ◽  
Henry Johansson ◽  
Sverker Ljunghall ◽  
Jan Malmaeus ◽  
...  
Keyword(s):  
Vitamin D ◽  
Parathyroid Hormone ◽  
Parathyroid Tissue ◽  
Vitamin D Metabolites ◽  
Hormone Release ◽  
High Doses ◽  
Parathyroid Hormone Release ◽  
Dispersed Cells

Abstract. The effects of 125-dihydroxycholecalciferol (1,25-(OH)2D3) and 24,25-dihydroxycholecalciferol (24,25-(OH)2D3) on parathyroid hormone (PTH) release from human parathyroid cells were investigated using an in vitro system of dispersed cells. The cells were obtained from 7 patients with primary hyperparathyroidism (HPT) and adenoma, 4 patients with primary HPT due to hyperplasia and 2 patients with parathyroid hyperplasia secondary to chronic renal failure. The dispersed cells were incubated in tissue culture medium at low, normal and high external calcium concentrations for 2–16 h. There was a gradual suppression of PTH release (5–55%) when the calcium concentration in the medium was increased from 0.5 to 3.0 mM, thus indicating retained regulation of hormone release. The addition of 1,25-(OH)2D3 in concentrations of 0.1 and 1 ng/ml and of 24,25-(OH)2D3 in concentrations of 1.0 and 10 ng/ml during the incubations did not further affect the amount of PTH released by the cells. The concentrations of the different vitamin D metabolites tested closely correspond to levels observed under normal physiological conditions and during treatment with high doses of vitamin D in vivo. Thus, the findings contradict the idea of any direct short-term regulatory effect of either 1,25-(OH)2D3 or 24,25-(OH)2D3 on the secretion of PTH from hyperfunctioning human parathyroid tissue.

In Vitro Toxicity of Fludarabine on Normal Bone Marrow (BM) Progenitors Suggests Its Involvement in the Impairment of Hematopoietic Progenitor (HP) Mobilization.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 1192-1192
Author(s):  
Céline Richard ◽  
Véronique Maguer-Satta ◽  
Juliette Berger ◽  
Sandrine Jeanpierre ◽  
Franck E. Nicolini ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Mononuclear Cells ◽  
Blood Platelet ◽  
Biological Properties ◽  
Lymphocytic Leukemia ◽  
In Vitro Toxicity ◽  
Bone Marrow Niche ◽  
Dose Dependent

Abstract Fludarabine phosphate (FDR) is considered the most effective drug for treating aggressive B-cell Chronic Lymphocytic Leukemia (B-CLL). Nevertheless, several groups have reported negative effects on BM HP mobilization by G-CSF alone after several months and sometimes correlated with the blood platelet count. As it was previously reported that in vivo FDR-induced cytopenia suggesting toxicity towards HP, we postulate that FDR could impair two major cell components of the bone marrow niche - mesenchymal (MP) and hematopoietic cells - and durably alter the HP egress process. We assessed the effects of increasing doses of FDR (for 5 days) on normal BM MP and HP biological properties, on HP adherence to fibronectin (Fn) or stromal cells and on SDF-1-induced in vitro migration. The expression of molecules involved in HP egress, i.e. CXCR4, CD49d and CD106, was evaluated by flow cytometry. As we demonstrated previously that all MP express CD73, an ecto-nucleotidase probably involved in FDR metabolism, we then tested the effect of a specific CD73 inhibitor (α, b methylene adenosine 5′-diphosphate (MADP)) on MP response to FDR treatment. In two independent series, we found a dose-dependent toxic effect of FDR on BM mononuclear cells, particularly on clonogenic mesenchymal progenitors (MP) (n=8) and hematopoietic progenitors (HP) (n=9). The most sensitive progenitors were MP, BFU-E and CFU-Mk (from 1mM dose) but other progenitors (CFU-GM, CFU-Mix), including the most primitive (LTC-IC) (n=3), were also dose-dependently sensitive. We found that toxicity of FDR on MP was CD73-independent since no improvement in cell survival was observed in presence of MADP (n=4). Interestingly, after expanding the surviving cells, we observed that FDR-induced impairment of the proliferative capacity of input MP was transmitted to cell progeny during the following passages. This means that progeny-derived cells, that have not been directly in contact with FDR, are still affected by the initial dose of FDR in a dose-dependent fashion. In the hematopoietic compartment, FDR had no effect on mononuclear cell adhesion, but there was an increase in the adhesion of HP colony-forming cells (CFC) which correlated with an inhibition of SDF-1 induced migration. However, FDR did not modify the expression of CXCR4, CD49d or CD106 on mesenchymal (CD45CD14) − /CD73+ cells or hematopoietic CD34+ cells. In conclusion, FDR appeared toxic towards clonogenic MP and HP, and profoundly impaired cell metabolism, since the effect persisted in cell progeny. The high sensitivity of the mesenchymal component suggests a possible impairment of BM stem cell niches. Although there was no modification of expression of molecules involved in egress, increased CFC adhesion and inhibition of HP migration suggest a FDR-induced retention of HSC in bone marrow. We are currently evaluating these parameters in MP and HP cells isolated from the bone marrow of CLL patients.

scholarly journals Stimulation of cell proliferation in skeletal tissues of the rat by defined parathyroid hormone fragments

1991 ◽  
Vol 277 (3) ◽  
pp. 863-868 ◽  
Author(s):  
D Sömjen ◽  
K D Schlüter ◽  
E Wingender ◽  
H Mayer ◽  
A M Kaye
Keyword(s):  
Parathyroid Hormone ◽  
Bone Resorption ◽  
Thymidine Incorporation ◽  
Specific Activity ◽  
Fold Increase ◽  
Dependent Manner ◽  
Equimolar Concentration ◽  
Dose Dependent

We have found, in previous studies in vitro using skeletal derived cell cultures, that mid-region fragments of human parathyroid hormone (hPTH) stimulate [3H]thymidine incorporation into DNA and increase the specific activity of the brain-type isoenzyme of creatine kinase (CK). These changes occurred without an increase in cyclic AMP formation which is linked to bone resorption. In this study, we found that the mid-region fragment hPTH-(28-48) stimulated CK activity in diaphysis, epiphysis and kidney in a time- and dose-dependent manner, parallel to the effects of the whole molecule bovine (b)PTH-(1-84) and the fully active fragment hPTH-(1-34). The increase caused by hPTH-(28-48) at a dose of 1.25 micrograms/rat was not less than the 2-fold increase caused by a roughly equimolar concentration bPTH-(1-84). A significant increase was reached at 1 h after intraperitoneal injection in all cases. All three sequences of PTH caused an increase in [3H]thymidine incorporation into DNA in diaphysis and epiphysis, but not in kidney, 24 h after injection. A fragment further towards the C-terminal, hPTH-(34-47), was inactive compared with an equimolar concentration of the fragment hPTH-(25-39), which stimulated both CK activity and DNA synthesis. These results in vivo are in line with previous findings in vitro; they provide further support for the suggestion that mid-region fragments of the PTH molecule could be used to induce bone formation without incurring the deleterious effect of bone resorption.

scholarly journals Semaphorin 3B Is a 1,25-Dihydroxyvitamin D3-Induced Gene in Osteoblasts that Promotes Osteoclastogenesis and Induces Osteopenia in Mice

2008 ◽  
Vol 22 (6) ◽  
pp. 1370-1381 ◽  
Author(s):  
Amelia L. M. Sutton ◽  
Xiaoxue Zhang ◽  
Diane R. Dowd ◽  
Yogendra P. Kharode ◽  
Barry S. Komm ◽  
...  
Keyword(s):  
Target Genes ◽  
Biological Effects ◽  
Osteoblastic Cells ◽  
Northern Analysis ◽  
Mineral Density ◽  
Dihydroxyvitamin D3 ◽  
1,25 Dihydroxyvitamin D3 ◽  
Skeletal Homeostasis

Abstract The vitamin D endocrine system is important for skeletal homeostasis. 1,25-Dihydroxyvitamin D3 [1,25(OH)2D3] impacts bone indirectly by promoting intestinal absorption of calcium and phosphate and directly by acting on osteoblasts and osteoclasts. Despite the direct actions of 1,25(OH)2D3 in bone, relatively little is known of the mechanisms or target genes that are regulated by 1,25(OH)2D3 in skeletal cells. Here, we identify semaphorin 3B (SEMA3B) as a 1,25(OH)2D3-stimulated gene in osteoblastic cells. Northern analysis revealed strong induction of SEMA3B mRNA by 1,25(OH)2D3 in MG-63, ST-2, MC3T3, and primary osteoblastic cells. Moreover, differentiation of these osteogenic cells enhanced SEMA3B gene expression. Biological effects of SEMA3B in the skeletal system have not been reported. Here, we show that osteoblast-derived SEMA3B alters global skeletal homeostasis in intact animals and osteoblast function in cell culture. Osteoblast-targeted expression of SEMA3B in mice resulted in reduced bone mineral density and aberrant trabecular structure compared with nontransgenic littermates. Histomorphometry studies indicated that this was likely due to increased osteoclast numbers and activity. Indeed, primary osteoblasts obtained from SEMA3B transgenic mice stimulated osteoclastogenesis to a greater extent than nontransgenic osteoblasts. This study establishes that SEMA3B is a 1,25(OH)2D3-induced gene in osteoblasts and that osteoblast-derived SEMA3B impacts skeletal biology in vitro and in vivo. Collectively, these studies support a putative role for SEMA3B as an osteoblast protein that regulates bone mass and skeletal homeostasis.

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