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Coltherd JC, Staunton R, Colyer A, Thomas G, Gilham M, Logan DW, Butterwick R, Watson P. Not all forms of dietary phosphorus are equal: an evaluation of postprandial phosphorus concentrations in the plasma of the cat. Br J Nutr 2019; 121:270-284. [PMID: 30420000 PMCID: PMC6390407 DOI: 10.1017/s0007114518003379] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 10/04/2018] [Accepted: 10/22/2018] [Indexed: 11/08/2022]
Abstract
Phosphorus is present in diets as naturally occurring P from raw materials or added as an inorganic salt. However, little is known about postprandial kinetics of P absorption in cats. Here, we describe several studies quantifying postprandial kinetics following the ingestion of diets of varying composition. Briefly, cats were fed a meal consisting of 50 % of their metabolic energy requirement in a randomised crossover design. A pre-meal baseline blood sample was taken via cephalic catheter and repeated measurements taken regularly up to 6 h post-meal to assess the whole blood ionised Ca, plasma P and parathyroid hormone concentrations. A diet containing 4·8 g total P/4184 kJ (1000 kcal), 3·5 g P from sodium dihydrogen phosphate (NaH2PO4)/4184 kJ (1000 kcal) and Ca:P 0·6 caused a marked increase in plasma P from baseline to a peak of 1·976 (95% CI 1·724, 2·266) mmol/l (P <0·001), whereas a diet containing 3·38 g total P/4184 kJ (1000 kcal), no added inorganic P and Ca:P 1·55 resulted in a postprandial decrease in plasma P (P = 0·008). Subsequent data indicate that added inorganic P salts in the diet above 0·5 g P/4184 kJ (1000 kcal) cause an increase in plasma P in cats, while diets below this do not. The data presented here demonstrate that sources of added inorganic P salts cause a temporary postprandial increase in plasma P in a dose-dependent manner, prolonged in diets with Ca:P <1·0. Dietary P derived from natural food ingredients (e.g. meat or vegetable matter) does not appear to have any effect on postprandial plasma P.
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Affiliation(s)
| | - Ruth Staunton
- WALTHAM Centre for Pet Nutrition, Melton Mowbray, Leicestershire LE14 4RT, UK
| | - Alison Colyer
- WALTHAM Centre for Pet Nutrition, Melton Mowbray, Leicestershire LE14 4RT, UK
| | - Gäelle Thomas
- WALTHAM Centre for Pet Nutrition, Melton Mowbray, Leicestershire LE14 4RT, UK
| | - Matthew Gilham
- WALTHAM Centre for Pet Nutrition, Melton Mowbray, Leicestershire LE14 4RT, UK
| | - Darren W. Logan
- WALTHAM Centre for Pet Nutrition, Melton Mowbray, Leicestershire LE14 4RT, UK
| | - Richard Butterwick
- WALTHAM Centre for Pet Nutrition, Melton Mowbray, Leicestershire LE14 4RT, UK
| | - Phillip Watson
- WALTHAM Centre for Pet Nutrition, Melton Mowbray, Leicestershire LE14 4RT, UK
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The Association of Fibroblast Growth Factor-23 with Mineral Factors (Ca, P, and Mg), Parathyroid Hormone, and 25-Hydroxyvitamin D in Hemodialysis Patients: A Multicenter Study. Nephrourol Mon 2018. [DOI: 10.5812/numonthly.84296] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Rodelo-Haad C, Rodríguez-Ortiz ME, Martin-Malo A, Pendon-Ruiz de Mier MV, Agüera ML, Muñoz-Castañeda JR, Soriano S, Caravaca F, Alvarez-Lara MA, Felsenfeld A, Aljama P, Rodriguez M. Phosphate control in reducing FGF23 levels in hemodialysis patients. PLoS One 2018; 13:e0201537. [PMID: 30086150 PMCID: PMC6080760 DOI: 10.1371/journal.pone.0201537] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 07/04/2018] [Indexed: 02/07/2023] Open
Abstract
Background In hemodialysis patients, high levels of Fibroblast Growth Factor 23 (FGF23) predict mortality. Our study was designed to test whether the control of serum phosphate is associated with a reduction in serum FGF23 levels. Additionally other variables with a potential effect on FGF23 levels were evaluated. Material and methods The effect of sustained (40-weeks) control of serum phosphate on FGF23 levels (intact and c-terminal) was evaluated in 21 stable hemodialysis patients that were not receiving calcimimetics or active vitamin D. Patients received non-calcium phosphate binders to maintain serum phosphate below 4.5 mg/dl. In an additional analysis, values of intact-FGF23 (iFGF23) and c-terminal FGF23 (cFGF23) from 150 hemodialysis patients were correlated with parameters of mineral metabolism and inflammation. Linear mixed models and linear regression were performed to evaluate longitudinal trajectories of variables and the association between FGF23 and the other variables examined. Results During the 40-week treatment, 12 of 21 patients achieved the target of serum phosphate <4.5 mg/dl. In these 12 patients, iFGF23 decreased to less than half whereas cFGF23 did not reduce significantly. In patients with serum phosphate >4.5 mg, iFGF23 and cFGF23 increased two and four-fold respectively as compared with baseline. Furthermore, changes in serum phosphate correlated with changes in C-reactive protein (hs-CRP). In our 150 hemodialysis patients, those in the higher tertile of serum phosphate also showed increased hs-CRP, iPTH, iFGF23 and cFGF23. Multiple regression analysis revealed that iFGF23 levels directly correlated with both serum phosphate and calcium, whereas cFGF23 correlated with serum phosphate and hs-CRP but not with calcium. Conclusions The control of serum phosphate reduced iFGF23. This reduction was also associated with a decreased in inflammatory parameters. Considering the entire cohort of hemodialysis patients, iFGF23 levels correlated directly with serum phosphate levels and also correlated inversely with serum calcium concentration. The levels of cFGF23 were closely related to serum phosphate and parameters of inflammation.
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Affiliation(s)
- Cristian Rodelo-Haad
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Cordoba, Cordoba, Spain
- Nephrology Service, Reina Sofia University Hospital, Cordoba, Spain
- RETICs-REDinREN (National Institute of Health Carlos III), Madrid, Spain
| | - Maria E. Rodríguez-Ortiz
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Cordoba, Cordoba, Spain
- RETICs-REDinREN (National Institute of Health Carlos III), Madrid, Spain
| | - Alejandro Martin-Malo
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Cordoba, Cordoba, Spain
- Nephrology Service, Reina Sofia University Hospital, Cordoba, Spain
- RETICs-REDinREN (National Institute of Health Carlos III), Madrid, Spain
- * E-mail:
| | - M. Victoria Pendon-Ruiz de Mier
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Cordoba, Cordoba, Spain
- Nephrology Service, Reina Sofia University Hospital, Cordoba, Spain
- RETICs-REDinREN (National Institute of Health Carlos III), Madrid, Spain
| | - M. Luisa Agüera
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Cordoba, Cordoba, Spain
- Nephrology Service, Reina Sofia University Hospital, Cordoba, Spain
- RETICs-REDinREN (National Institute of Health Carlos III), Madrid, Spain
| | - Juan R. Muñoz-Castañeda
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Cordoba, Cordoba, Spain
- Nephrology Service, Reina Sofia University Hospital, Cordoba, Spain
- RETICs-REDinREN (National Institute of Health Carlos III), Madrid, Spain
| | - Sagrario Soriano
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Cordoba, Cordoba, Spain
- Nephrology Service, Reina Sofia University Hospital, Cordoba, Spain
- RETICs-REDinREN (National Institute of Health Carlos III), Madrid, Spain
| | | | - M. Antonia Alvarez-Lara
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Cordoba, Cordoba, Spain
- Nephrology Service, Reina Sofia University Hospital, Cordoba, Spain
- RETICs-REDinREN (National Institute of Health Carlos III), Madrid, Spain
| | - Arnold Felsenfeld
- Wadsworth VA, UCLA, Department of Medicine, Veterans Affairs Greater Los Angeles Healthcare System and the David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California
| | - Pedro Aljama
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Cordoba, Cordoba, Spain
- Nephrology Service, Reina Sofia University Hospital, Cordoba, Spain
- RETICs-REDinREN (National Institute of Health Carlos III), Madrid, Spain
| | - Mariano Rodriguez
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Cordoba, Cordoba, Spain
- Nephrology Service, Reina Sofia University Hospital, Cordoba, Spain
- RETICs-REDinREN (National Institute of Health Carlos III), Madrid, Spain
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Chen X, Chen X, Wu W, Zhou Q, Gong X, Shi B. Effects of FGF‐23‐mediated ERK/MAPK signaling pathway on parathyroid hormone secretion of parathyroid cells in rats with secondary hyperparathyroidism. J Cell Physiol 2018; 233:7092-7102. [PMID: 29633272 DOI: 10.1002/jcp.26525] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 01/30/2018] [Indexed: 12/28/2022]
Affiliation(s)
- Xiao‐Jun Chen
- Department of EndocrinologyThe First Affiliated Hospital of Soochow UniversitySuzhouP.R. China
- Department of EndocrinologyThe First Affiliated Hospital of Wenzhou Medical UniversityWenzhouP.R. China
| | - Xiong Chen
- Department of EndocrinologyThe First Affiliated Hospital of Wenzhou Medical UniversityWenzhouP.R. China
| | - Wen‐Jun Wu
- Department of EndocrinologyThe First Affiliated Hospital of Wenzhou Medical UniversityWenzhouP.R. China
| | - Qi Zhou
- Department of EndocrinologyThe First Affiliated Hospital of Wenzhou Medical UniversityWenzhouP.R. China
| | - Xiao‐Hua Gong
- Department of EndocrinologyThe First Affiliated Hospital of Wenzhou Medical UniversityWenzhouP.R. China
| | - Bi‐Min Shi
- Department of EndocrinologyThe First Affiliated Hospital of Soochow UniversitySuzhouP.R. China
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Abstract
Calcium is an important ion in cell signaling, hormone regulation, and bone health. Its regulation is complex and intimately connected to that of phosphate homeostasis. Both ions are maintained at appropriate levels to maintain the extracellular to intracellular gradients, allow for mineralization of bone, and to prevent extra skeletal and urinary calcification. The homeostasis involves the target organs intestine, parathyroid glands, kidney, and bone. Multiple hormones converge to regulate the extracellular calcium level: parathyroid hormone, vitamin D (principally 25(OH)D or 1,25(OH)2D), fibroblast growth factor 23, and α-klotho. Fine regulation of calcium homeostasis occurs in the thick ascending limb and collecting tubule segments via actions of the calcium sensing receptor and several channels/transporters. The kidney participates in homeostatic loops with bone, intestine, and parathyroid glands. Initially in the course of progressive kidney disease, the homeostatic response maintains serum levels of calcium and phosphorus in the desired range, and maintains neutral balance. However, once the kidneys are no longer able to appropriately respond to hormones and excrete calcium and phosphate, positive balance ensues leading to adverse cardiac and skeletal abnormalities. © 2016 American Physiological Society. Compr Physiol 6:1781-1800, 2016.
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Affiliation(s)
- Sharon M Moe
- Division of Nephrology, Indiana University School of Medicine, Roudebush Veterans Administration Medical Center, Indianapolis, Indiana.,Section of Nephrology, Roudebush Veterans Administration Medical Center, Indianapolis, Indiana
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Cao Y, Gomes SA, Rangel EB, Paulino EC, Fonseca TL, Li J, Teixeira MB, Gouveia CH, Bianco AC, Kapiloff MS, Balkan W, Hare JM. S-nitrosoglutathione reductase-dependent PPARγ denitrosylation participates in MSC-derived adipogenesis and osteogenesis. J Clin Invest 2015; 125:1679-91. [PMID: 25798618 DOI: 10.1172/jci73780] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 02/06/2015] [Indexed: 01/04/2023] Open
Abstract
Bone marrow-derived mesenchymal stem cells (MSCs) are a common precursor of both adipocytes and osteoblasts. While it is appreciated that PPARγ regulates the balance between adipogenesis and osteogenesis, the roles of additional regulators of this process remain controversial. Here, we show that MSCs isolated from mice lacking S-nitrosoglutathione reductase, a denitrosylase that regulates protein S-nitrosylation, exhibited decreased adipogenesis and increased osteoblastogenesis compared with WT MSCs. Consistent with this cellular phenotype, S-nitrosoglutathione reductase-deficient mice were smaller, with reduced fat mass and increased bone formation that was accompanied by elevated bone resorption. WT and S-nitrosoglutathione reductase-deficient MSCs exhibited equivalent PPARγ expression; however, S-nitrosylation of PPARγ was elevated in S-nitrosoglutathione reductase-deficient MSCs, diminishing binding to its downstream target fatty acid-binding protein 4 (FABP4). We further identified Cys 139 of PPARγ as an S-nitrosylation site and demonstrated that S-nitrosylation of PPARγ inhibits its transcriptional activity, suggesting a feedback regulation of PPARγ transcriptional activity by NO-mediated S-nitrosylation. Together, these results reveal that S-nitrosoglutathione reductase-dependent modification of PPARγ alters the balance between adipocyte and osteoblast differentiation and provides checkpoint regulation of the lineage bifurcation of these 2 lineages. Moreover, these findings provide pathophysiological and therapeutic insights regarding MSC participation in adipogenesis and osteogenesis.
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Wesseling-Perry K, Wang H, Elashoff R, Gales B, Jüppner H, Salusky IB. Lack of FGF23 response to acute changes in serum calcium and PTH in humans. J Clin Endocrinol Metab 2014; 99:E1951-6. [PMID: 25062462 PMCID: PMC5393489 DOI: 10.1210/jc.2014-2125] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
CONTEXT 1,25-Dihydroxyvitamin D (1,25D) administration and long-term increases in phosphate, PTH, and calcium concentrations are associated with increases in circulating fibroblast growth factor 23 (FGF23); however, whether or not acute changes in serum calcium modulate short-term FGF23 release is unknown. OBJECTIVE/DESIGN To assess the direct effect of acute changes in calcium and PTH on circulating FGF23 levels. SETTING A university clinical and translational research center. PATIENTS/PARTICIPANTS Twelve healthy volunteers and 10 dialysis patients. INTERVENTIONS Calcium gluconate and sodium citrate were infused for 120 minutes on 2 consecutive days. MAIN OUTCOME MEASURES Serum levels of ionized calcium, phosphorus, PTH, 1,25D, and plasma C-terminal FGF23 levels were obtained at 0, 13, 30, 60, 90, and 120 minutes during the infusions. RESULTS During the calcium infusion, serum calcium concentrations increased from 1.33 ± 0.01 to 1.57 ± 0.04 mmol/L (P < .05 from baseline) and from 1.20 ± 0.05 to 1.50 ± 0.03 mmol/L (P < .05 from baseline) in healthy subjects and in dialysis patients, respectively, whereas serum calcium values decreased from 1.33 ± 0.01 to 1.03 ± 0.02 mmol/L (P < .05 from baseline) and from 1.26 ± 0.04 to 1.07 ± 0.03 mmol/L (P < .05 from baseline) in the two groups, respectively during the sodium citrate infusion. PTH levels decreased from 35 (29, 57) to 8 (2,10) pg/mL (healthy subjects) (P < .05 from baseline) and from 292 (109, 423) to 44 (28, 86) pg/mL (dialysis patients) (P < .05 from baseline) during the calcium infusion and rose from 31 (25, 56) to 122 (95, 157) pg/mL and from 281 (117, 607) to 468 (169, 928) pg/mL (P < .05 from baseline) during sodium citrate infusion. Serum 1,25D levels and plasma FGF23 values remained unchanged during both infusions in both groups. CONCLUSIONS Short-term changes in calcium and PTH levels do not affect FGF23 concentrations in either healthy volunteers or dialysis patients.
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Affiliation(s)
- Katherine Wesseling-Perry
- Department of Pediatrics (K.W.-P., H.W., R.E., B.G., I.B.S.), David Geffen School of Medicine at the University of California Los Angeles, Los Angeles, California 90095; and Endocrine Unit and Division of Pediatric Nephrology (H.J.), Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
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Nygaard B, Frandsen NE, Brandi L, Rasmussen K, Oestergaard OV, Oedum L, Hoeck HC, Hansen D. Effects of high doses of cholecalciferol in normal subjects: a randomized double-blinded, placebo-controlled trial. PLoS One 2014; 9:e102965. [PMID: 25166750 PMCID: PMC4148309 DOI: 10.1371/journal.pone.0102965] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Accepted: 06/20/2014] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Vitamin D repletion with high doses of vitamin D is often recommended to patients and healthy subjects. The safety, especially concerning changes in urinary calcium excretion is of great importance. METHODS In a double-blinded, placebo-controlled study in 40 healthy volunteers, we examined the changes in mineral metabolism during supplementation with 3000 IU of oral cholecalciferol daily during 4 months. RESULTS Both 25(OH)vitamin D and 1,25(OH)2vitamin D increased significantly in the active treated group as compared to the placebo group (186% versus 14% (P<0.001) and 28% versus -8% (P<0.001)). No change was observed in urinary calcium excretion in the active group compared to the placebo group (P = 0.891). Fibroblast growth factor 23 increased significantly by 10% (P<0.018) in the active group. However, there was no difference in changes in FGF23 between treatment groups (P = 0.457). CONCLUSION High dose cholecalciferol significantly increases 25(OH)vitamin D and 1,25(OH)2vitamin D levels compared to placebo. No changes in urinary calcium excretion or other measured components of the mineral metabolism were found between groups. TRIAL REGISTRATION ClinicalTrials.gov NCT00952562.
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Affiliation(s)
- Birgitte Nygaard
- Department of Medicine, Roskilde University Hospital, Roskilde, Denmark
| | | | - Lisbet Brandi
- Department of Medicine, Roskilde University Hospital, Roskilde, Denmark
| | - Knud Rasmussen
- Department of Medicine, Roskilde University Hospital, Roskilde, Denmark
| | | | - Lars Oedum
- Department of Clinical Biochemistry, Roskilde University Hospital, Roskilde, Denmark
| | | | - Ditte Hansen
- Department of Medicine, Roskilde University Hospital, Roskilde, Denmark
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Tsujita M, Inaguma D, Goto N, Yamamoto T, Hiramitsu T, Katayama A, Takeda A, Kobayashi T, Morozumi K, Uchida K, Narumi S, Watarai Y, Tominaga Y. Beneficial effects of preemptive kidney transplantation on calcium and phosphorus disorders in early post-transplant recipients. Clin Exp Nephrol 2014; 19:319-24. [PMID: 24706030 DOI: 10.1007/s10157-014-0967-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 03/13/2014] [Indexed: 11/26/2022]
Abstract
BACKGROUND Recently, preemptive kidney transplantation (PKT) has increased in Japan; however, the effects of PKT on calcium (Ca) and phosphorus (Pi) metabolism are poorly understood. METHODS Thirty-two consecutive patients were enrolled in this study at Nagoya Daini Red Cross Hospital. Fifteen patients were in the PKT group and 17 patients were in the non-PKT group. Parameters of Ca and Pi metabolism, including fibroblast growth factor (FGF) 23 and intact parathyroid hormone, were measured before transplantation and 1, 3, and 24 weeks after transplantation. RESULTS FGF 23 decreased dramatically in both groups after transplantation; however, FGF 23 before transplantation and at 1 and 3 weeks after transplantation was significantly lower in the PKT group than in the non-PKT group (p < 0.05). Although iPTH levels were higher in the PKT group than in the non-PKT group before transplantation, these levels were lower in the PKT group at 24 weeks after transplantation (p < 0.05). Corrected Ca was lower at 24 weeks in the PKT group (p < 0.05), whereas Pi was lower in the non-PKT group at 1 and 3 weeks (p < 0.05), but not significantly different at 24 weeks. Multivariate linear regression analysis revealed that FGF 23 before transplantation was the strongest predictor of Ca and Pi disorders in early post-transplant recipients. CONCLUSIONS This study suggests that PKT has beneficial effects on Ca and Pi metabolism and pre-transplant FGF 23 levels are a good marker of post-transplant Ca and Pi metabolism disorders.
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Affiliation(s)
- Makoto Tsujita
- Department of the Kidney Disease Center, Nagoya Daini Red Cross Hospital, 2-9 Myoken-cho, Showa-ku, Nagoya, 466-8650, Japan,
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Abstract
Teeth are mineralized organs composed of three unique hard tissues, enamel, dentin, and cementum, and supported by the surrounding alveolar bone. Although odontogenesis differs from osteogenesis in several respects, tooth mineralization is susceptible to similar developmental failures as bone. Here we discuss conditions fitting under the umbrella of rickets, which traditionally referred to skeletal disease associated with vitamin D deficiency but has been more recently expanded to include newly identified factors involved in endocrine regulation of vitamin D, phosphate, and calcium, including phosphate-regulating endopeptidase homolog, X-linked, fibroblast growth factor 23, and dentin matrix protein 1. Systemic mineral metabolism intersects with local regulation of mineralization, and factors including tissue nonspecific alkaline phosphatase are necessary for proper mineralization, where rickets can result from loss of activity of tissue nonspecific alkaline phosphatase. Individuals suffering from rickets often bear the additional burden of a defective dentition, and transgenic mouse models have aided in understanding the nature and mechanisms involved in tooth defects, which may or may not parallel rachitic bone defects. This report reviews dental effects of the range of rachitic disorders, including discussion of etiologies of hereditary forms of rickets, a survey of resulting bone and tooth mineralization disorders, and a discussion of mechanisms, known and hypothesized, involved in the observed dental pathologies. Descriptions of human pathology are augmented by analysis of transgenic mouse models, and new interpretations are brought to bear on questions of how teeth are affected under conditions of rickets. In short, the rachitic tooth will be revealed.
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Affiliation(s)
- Brian L Foster
- National Institute for Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Maryland 20892
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Covic A, Passlick-Deetjen J, Kroczak M, Büschges-Seraphin B, Ghenu A, Ponce P, Marzell B, de Francisco ALM. A comparison of calcium acetate/magnesium carbonate and sevelamer-hydrochloride effects on fibroblast growth factor-23 and bone markers: post hoc evaluation from a controlled, randomized study. Nephrol Dial Transplant 2013; 28:2383-92. [PMID: 23787550 PMCID: PMC3769980 DOI: 10.1093/ndt/gft203] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Different phosphate binders exert differing effects on bone mineral metabolism and levels of regulating hormones. The objective of this post hoc evaluation of the CALcium acetate MAGnesium carbonate (CALMAG) study was to compare the effects of calcium acetate/magnesium carbonate (CaMg) and a calcium-free phosphate binder, sevelamer-hydrochloride (HCl), on serum levels of fibroblast growth factor-23 (FGF-23) and markers of bone turnover. METHODS This secondary analysis of the controlled, randomized CALMAG study, comparing the effect of CaMg and sevelamer-HCl on serum phosphorus (P), aimed to investigate the parameters described above. The analysis included 204 patients who completed the initial study per protocol (CaMg, n = 105; sevelamer-HCl, n = 99). RESULTS The study showed that serum levels of FGF-23 were significantly reduced with CaMg and sevelamer-HCl, with no difference between groups at Week 25 [analysis of covariance (ANCOVA); log-intact FGF-23 (iFGF-23), P = 0.1573]. FGF-23 levels strongly correlated with serum P levels at all time points in both groups. The bone turnover parameters alkaline phosphatase (AP), bone AP (BAP), procollagen type 1 amino-terminal propeptide 1 (P1NP), osteoprotegerin (OPG), beta-crosslaps (β-CTX) and tartrate-resistant acid phosphatase 5b (TRAP 5b) increased significantly in the sevelamer-HCl group; they remained almost unchanged in the CaMg group, after the initial phase of P lowering (ANCOVA, P < 0.0001 for all except OPG, P = 0.1718). CONCLUSIONS CaMg and sevelamer-HCl comparably lower serum levels of iFGF-23. Changes in bone parameters were dependent on characteristics of the phosphate binder; in contrast with sevelamer-HCl, CaMg had no influence on bone turnover markers.
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Affiliation(s)
- Adrian Covic
- Clinic of Nephrology, C. I. Parhon University Hospital, Gr T. Popa; University of Medicine and Pharmacy, IASI, Romania
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Quarles LD. Role of FGF23 in vitamin D and phosphate metabolism: implications in chronic kidney disease. Exp Cell Res 2012; 318:1040-8. [PMID: 22421513 PMCID: PMC3336874 DOI: 10.1016/j.yexcr.2012.02.027] [Citation(s) in RCA: 176] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Accepted: 02/24/2012] [Indexed: 01/04/2023]
Abstract
FGF23 is a bone-derived hormone that regulates systemic phosphate homeostasis, vitamin D metabolism and α-Klotho expression through a novel bone-kidney axis. FGF23 inhibits renal tubular reabsorption of phosphate through mechanisms independent of PTH as well as reduces circulating 1, 25(OH)(2)D through its dual effects to suppress Cyp27b1 production and to stimulate Cyp24 catabolism of 1,25(OH)(2)D. 1,25(OH)(2)D and other factors regulating bone remodeling/mineralization are the major physiological regulators of FGF23 expression. FGF23 also suppresses the gene transcription of α-klotho by the kidney, which exists as a membrane and soluble protein. Membrane Klotho acts as a coreceptor for and dictates organ specificity of FGF23, whereas soluble Klotho act as an endocrine factor that regulates activity of cell surface glycoproteins and receptors in multiple tissues. Elevated FGF23 levels are responsible for several hereditary and acquired hypophosphatemic rickets disorders. FGF23 and Klotho deficiency have similar phenotypes characterized by hyperphosphatemia, elevated 1,25(OH)(2)D and tumoral calcinosis. FGF23 levels progressively increase during chronic kidney disease (CKD). FGF23 has been proposed to be the initial adaptive response leading to reductions in 1,25(OH)(2)D and secondary hyperparathyroidism (HPT) in CKD. The overall biological effect of this initial step may be to orchestrate a coordinated adaptation to protect the organism from the adverse effects of excess phosphate retention. The second step involves the effects of PTH on bone remodeling that further stimulates FGF23 production through both direct and indirect mechanisms related to alterations in extracellular matrix factors. PTH further amplifies FGF23 expression in later stages of CKD to compensate for the increased phosphate efflux from bone caused by excessive bone turnover. While many aspects of the regulation and functions of FGF23 remain to be established, the idea that FGF23 hormone is the initial adaptive hormonal response in CKD that suppresses 1,25(OH)(2)D, reduces gastrointestinal calcium and phosphate absorption and leads to a secondary HPT represents a paradigm shift in the conceptualization of the pathogenesis of secondary hyperparathyroidism. In addition, the prevalent thought that CKD is a functional "vitamin D deficient state" requiring therapy with 1,25(OH)(2)D analogs is challenged by effects of FGF23 to potentially lower both 25(OH)D and 1,25(OH)D by induction of Cyp24-mediated degradation. Finally, increments in FGF23 are associated with increased cardiovascular mortality in CKD. Whether these effects represent direct effects of FGF23 or represent a marker of other abnormalities in CKD remains to be determined.
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Affiliation(s)
- L Darryl Quarles
- Department of Medicine and Division of Nephrology, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
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Hryszko T, Brzosko S, Rydzewska-Rosolowska A, Koc-Zorawska E, Mysliwiec M. Cinacalcet lowers FGF-23 level together with bone metabolism in hemodialyzed patients with secondary hyperparathyroidism. Int Urol Nephrol 2011; 44:1479-86. [DOI: 10.1007/s11255-011-0050-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Accepted: 08/13/2011] [Indexed: 02/07/2023]
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