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Wang W, Yang Y, Wang D, Huang L. Toxic Effects of Rare Earth Elements on Human Health: A Review. TOXICS 2024; 12:317. [PMID: 38787096 PMCID: PMC11125915 DOI: 10.3390/toxics12050317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2024] [Revised: 04/18/2024] [Accepted: 04/25/2024] [Indexed: 05/25/2024]
Abstract
Rare earth elements (REEs) are a new type of material resource which have attracted significant attention in recent years. REEs have emerged as essential metals in modern-day technology due to their unique functions. The long-term, large-scale mining and utilization of rare earths has caused serious environmental pollution and constitutes a global health issue, which has raised concerns regarding the safety of human health. However, the toxicity profile of suspended particulate matter in REEs in the environment, which interacts with the human body, remains largely unknown. Studies have shown that REEs can enter the human body through a variety of pathways, leading to a variety of organ and system dysfunctions through changes in genetics, epigenetics, and signaling pathways. Through an extensive literature search and critical analysis, we provide a comprehensive overview of the available evidence, identify knowledge gaps, and make recommendations for future research directions.
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Affiliation(s)
| | | | | | - Lihua Huang
- School of Public Health, Baotou Medical College, Baotou 014030, China; (W.W.); (Y.Y.); (D.W.)
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Huang J, Lv Z, Wang Y, Wang Z, Gao T, Zhang N, Guo M, Zou H, Zhang P. In Vivo MRI and X-Ray Bifunctional Imaging of Polymeric Composite Supplemented with GdPO4 ·H2 O Nanobundles for Tracing Bone Implant and Bone Regeneration. Adv Healthc Mater 2016; 5:2182-90. [PMID: 27385162 DOI: 10.1002/adhm.201600249] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 06/06/2016] [Indexed: 12/12/2022]
Abstract
Homogeneous and monodisperse GdPO4 ·H2 O nanobundles are successfully synthesized via a solvothermal method. Then, GdPO4 ·H2 O are incorporated into the composite of hydroxyapatite and poly(lactic-co-glycolic acid) to obtain a biodegradable and traceable bone implant. After implanted, the GdPO4 ·H2 O/HA/PLGA implant and the newly formed bone can be easily traced and observed through the combination of magnetic resonance imaging and X-ray imaging.
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Affiliation(s)
- Jing Huang
- College of Chemistry; Jilin University; Changchun 130012 P. R. China
- Key Laboratory of Polymer Ecomaterials; Changchun Institute of Applied Chemistry; Chinese Academy of Sciences; Changchun 130022 P. R. China
| | - Zhongwen Lv
- China-Japan Union Hospital; Jilin University; Changchun 130021 P. R. China
| | - Yu Wang
- Key Laboratory of Polymer Ecomaterials; Changchun Institute of Applied Chemistry; Chinese Academy of Sciences; Changchun 130022 P. R. China
| | - Zongliang Wang
- Key Laboratory of Polymer Ecomaterials; Changchun Institute of Applied Chemistry; Chinese Academy of Sciences; Changchun 130022 P. R. China
| | - Tianlin Gao
- Key Laboratory of Polymer Ecomaterials; Changchun Institute of Applied Chemistry; Chinese Academy of Sciences; Changchun 130022 P. R. China
- School of Public Health; Jilin University; Changchun 130021 P. R. China
| | - Ning Zhang
- Department of Foot and Ankle Surgery; The Second Hospital of Shandong University; Jinan 250000 P. R. China
| | - Min Guo
- Key Laboratory of Polymer Ecomaterials; Changchun Institute of Applied Chemistry; Chinese Academy of Sciences; Changchun 130022 P. R. China
| | - Haifeng Zou
- College of Chemistry; Jilin University; Changchun 130012 P. R. China
| | - Peibiao Zhang
- Key Laboratory of Polymer Ecomaterials; Changchun Institute of Applied Chemistry; Chinese Academy of Sciences; Changchun 130022 P. R. China
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Carrillo-López N, Fernández-Martín JL, Alvarez-Hernández D, González-Suárez I, Castro-Santos P, Román-García P, López-Novoa JM, Cannata-Andía JB. Lanthanum activates calcium-sensing receptor and enhances sensitivity to calcium. Nephrol Dial Transplant 2010; 25:2930-7. [PMID: 20233740 DOI: 10.1093/ndt/gfq124] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND The aim of this study was to investigate whether nanomolar concentrations of lanthanum could influence the calcium-sensing receptor (CaSR) response. METHODS Embryonic kidney (HEK-293) cells transiently transfected with the human CaSR were used to test the ability of lanthanum to activate the CaSR, either alone or in combination with calcium. CaSR activation was measured by flow cytometry. Parathyroid glands from 4-month-old male Wistar rats with normal renal function (n = 60) were also cultured ex vivo with different concentrations of lanthanum to measure parathyroid hormone (PTH) secreted to the medium and PTH mRNA. RESULTS The maximal CaSR activation induced by 1 muM lanthanum chloride (LaCl(3)) was similar to that induced by 16 mM calcium chloride (CaCl(2) 16 mM: 294 +/- 14%; LaCl(3) 1 muM: 303 +/- 11%). Lanthanum half effective concentration (EC(50)) was 77.28 nM, lower than the 2.30 mM obtained for calcium, supporting the concept that this metal is a strong agonist of the CaSR. Moreover, lanthanum was also able to enhance CaSR sensitivity to calcium. The presence of 1 nM LaCl(3) significantly left-shifted the CaSR response curve, changing the EC(50) value for calcium from 2.30 mM (calcium alone) to 1.26 mM (calcium + 1 nM lanthanum). The parathyroid glands cultured with lanthanum showed a trend to secrete less PTH compared to the control glands: 1.51 +/- 0.23 (control), 0.91 +/- 0.17 (La 100 nM) and 1.04 +/- 0.18 (La 400 nM) [(pg/h)/(pg/h), mean +/- SEM] (ANOVA P = 0.0145). A similar trend was also observed in PTH synthesis measured by PTH mRNA levels. CONCLUSIONS These in vitro findings demonstrate that lanthanum, at nanomolar concentrations, is an agonist of the CaSR able to activate it in the absence of calcium. In addition, it can also enhance CaSR sensitivity to calcium, modulating PTH synthesis and secretion.
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Affiliation(s)
- Natalia Carrillo-López
- Bone and Mineral Research Unit, Instituto Reina Sofía de Investigación, REDinREN del ISCIII, Hospital Universitario Central de Asturias, Universidad de Oviedo, C/Julián Clavería s/n, 33006 Oviedo, Spain
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Abstract
Calcium transport and calcium signalling mechanisms in bone cells have, in many cases, been discovered by study of diseases with disordered bone metabolism. Calcium matrix deposition is driven primarily by phosphate production, and disorders in bone deposition include abnormalities in membrane phosphate transport such as in chondrocalcinosis, and defects in phosphate-producing enzymes such as in hypophosphatasia. Matrix removal is driven by acidification, which dissolves the mineral. Disorders in calcium removal from bone matrix by osteoclasts cause osteopetrosis. On the other hand, although bone is central to management of extracellular calcium, bone is not a major calcium sensing organ, although calcium sensing proteins are expressed in both osteoblasts and osteoclasts. Intracellular calcium signals are involved in secondary control including cellular motility and survival, but the relationship of these findings to specific diseases is not clear. Intracellular calcium signals may regulate the balance of cell survival versus proliferation or anabolic functional response as part of signalling cascades that integrate the response to primary signals via cell stretch, estrogen, tyrosine kinase, and tumor necrosis factor receptors.
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Affiliation(s)
- H C Blair
- Department of Pathology, University of Pittsburgh, PA 15261, USA
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Zaidi M, Moonga BS, Huang CLH. Calcium sensing and cell signaling processes in the local regulation of osteoclastic bone resorption. Biol Rev Camb Philos Soc 2004; 79:79-100. [PMID: 15005174 DOI: 10.1017/s1464793103006262] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The skeletal matrix in terrestrial vertebrates undergoes continual cycles of removal and replacement in the processes of bone growth, repair and remodeling. The osteoclast is uniquely important in bone resorption and thus is implicated in the pathogenesis of clinically important bone and joint diseases. Activated osteoclasts form a resorptive hemivacuole with the bone surface into which they release both acid and osteoclastic lysosomal hydrolases. This article reviews cell physiological studies of the local mechanisms that regulate the resorptive process. These used in vitro methods for the isolation, culture and direct study of the properties of neonatal rat osteoclasts. They demonstrated that both local microvascular agents and products of the bone resorptive process such as ambient Ca2+ could complement longer-range systemic regulatory mechanisms such as those that might be exerted through calcitonin (CT). Thus elevated extracellular [Ca2+], or applications of surrogate divalent cation agonists for Ca2+, inhibited bone resorptive activity and produced parallel increases in cytosolic [Ca2+], cell retraction and longer-term inhibition of enzyme release in isolated rat osteoclasts. These changes showed specificity, inactivation, and voltage-dependent properties that implicated a cell surface Ca2+ receptor (CaR) sensitive to millimolar extracellular [Ca2+]. Pharmacological, biophysical and immunochemical evidence implicated a ryanodine-receptor (RyR) type II isoform in this process and localized it to a unique, surface membrane site, with an outward-facing channel-forming domain. Such a surface RyR might function either directly or indirectly in the process of extracellular [Ca2+] sensing and in turn be modulated by cyclic adenosine diphosphate ribose (cADPr) produced by the ADP-ribosyl cyclase, CD38. The review finishes by speculating about possible detailed models for these transduction events and their possible interactions with other systemic mechanisms involved in Ca2+ homeostasis as well as the possible role of the RyR-based signaling mechanisms in longer-term cell regulatory processes.
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Affiliation(s)
- Mone Zaidi
- Mount Sinai Bone Program, Department of Medicine, Mount Sinai School of Medicine, New York, NY 10029, USA
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6
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Effects of the rare earth ions on bone resorbing function of rabbit mature osteoclastsin vitro. CHINESE SCIENCE BULLETIN-CHINESE 2003. [DOI: 10.1007/bf03182845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Moonga BS, Li S, Iqbal J, Davidson R, Shankar VS, Bevis PJR, Inzerillo A, Abe E, Huang CLH, Zaidi M. Ca(2+) influx through the osteoclastic plasma membrane ryanodine receptor. Am J Physiol Renal Physiol 2002; 282:F921-32. [PMID: 11934703 DOI: 10.1152/ajprenal.00045.2000] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We predict that the type 2 ryanodine receptor isoform (RyR-2) located in the osteoclastic membrane functions as a Ca(2+) influx channel and as a divalent cation (Ca(2+)) sensor. Cytosolic Ca(2+) measurements revealed Ca(2+) influx in osteoclasts at depolarized membrane potentials. The cytosolic Ca(2+) change was, as expected, not seen in Ca(2+)-free medium and was blocked by the RyR modulator ryanodine. In contrast, at basal membrane potentials (approximately 25 mV) ryanodine triggered extracellular Ca(2+) influx that was blocked by Ni(2+). In parallel, single-channel recordings obtained from inside-out excised patches revealed a divalent cation-selective approximately 60-pS conductance in symmetric solutions of Ba-aspartate [Ba-Asp; reversal potential (E(rev)) approximately 0 mV]. In the presence of a Ba(2+) gradient, i.e., with Ba-Asp in the pipette and Na-Asp in the bath, channel conductance increased to approximately 120 pS and E(rev) shifted to 21 mV. The conductance was tentatively classified as a RyR-gated Ca(2+) channel as it displayed characteristic metastable states and was sensitive to ruthenium red and a specific anti-RyR antibody, Ab(34). To demonstrate that extracellular Ca(2+) sensing occurred at the osteoclastic surface rather than intracellularly, we performed protease protection assays using pronase. Preincubation with pronase resulted in markedly attenuated cytosolic Ca(2+) signals triggered by either Ni(2+) (5 mM) or Cd(2+) (50 microM). Finally, intracellular application of antiserum Ab(34) potently inhibited divalent cation sensing. Together, these results strongly suggest the existence of 1) a membrane-resident Ca(2+) influx channel sensitive to RyR modulators; 2) an extracellular, as opposed to intracellular, divalent cation activation site; and 3) a cytosolic CaM-binding regulatory site for RyR. It is likely therefore that the surface RyR-2 not only gates Ca(2+) influx but also functions as a sensor for extracellular divalent cations.
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Affiliation(s)
- Baljit S Moonga
- Mount Sinai Bone Program, Department of Medicine, Mount Sinai School of Medicine, Bronx Veterans Affairs Medical Center, New York 10029, USA
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8
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Abstract
The cloning of a G protein-coupled extracellular Ca(2+) (Ca(o)(2+))-sensing receptor (CaR) has elucidated the molecular basis for many of the previously recognized effects of Ca(o)(2+) on tissues that maintain systemic Ca(o)(2+) homeostasis, especially parathyroid chief cells and several cells in the kidney. The availability of the cloned CaR enabled the development of DNA and antibody probes for identifying the CaR's mRNA and protein, respectively, within these and other tissues. It also permitted the identification of human diseases resulting from inactivating or activating mutations of the CaR gene and the subsequent generation of mice with targeted disruption of the CaR gene. The characteristic alterations in parathyroid and renal function in these patients and in the mice with "knockout" of the CaR gene have provided valuable information on the CaR's physiological roles in these tissues participating in mineral ion homeostasis. Nevertheless, relatively little is known about how the CaR regulates other tissues involved in systemic Ca(o)(2+) homeostasis, particularly bone and intestine. Moreover, there is evidence that additional Ca(o)(2+) sensors may exist in bone cells that mediate some or even all of the known effects of Ca(o)(2+) on these cells. Even more remains to be learned about the CaR's function in the rapidly growing list of cells that express it but are uninvolved in systemic Ca(o)(2+) metabolism. Available data suggest that the receptor serves numerous roles outside of systemic mineral ion homeostasis, ranging from the regulation of hormonal secretion and the activities of various ion channels to the longer term control of gene expression, programmed cell death (apoptosis), and cellular proliferation. In some cases, the CaR on these "nonhomeostatic" cells responds to local changes in Ca(o)(2+) taking place within compartments of the extracellular fluid (ECF) that communicate with the outside environment (e.g., the gastrointestinal tract). In others, localized changes in Ca(o)(2+) within the ECF can originate from several mechanisms, including fluxes of calcium ions into or out of cellular or extracellular stores or across epithelium that absorb or secrete Ca(2+). In any event, the CaR and other receptors/sensors for Ca(o)(2+) and probably for other extracellular ions represent versatile regulators of numerous cellular functions and may serve as important therapeutic targets.
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Affiliation(s)
- E M Brown
- Endocrine-Hypertension Division, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA.
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9
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Zaidi M, Moonga BS, Adebanjo OA. Novel mechanisms of calcium handling by the osteoclast: A review-hypothesis. PROCEEDINGS OF THE ASSOCIATION OF AMERICAN PHYSICIANS 1999; 111:319-27. [PMID: 10417740 DOI: 10.1046/j.1525-1381.1999.99233.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The osteoclast is a cell that is unique in its ability to resorb bone and, in doing so, becomes exposed to unusually high millimolar Ca2+ concentrations. It is generally accepted that, during resorption, osteoclasts can "sense" changes in their ambient Ca2+ concentration. This triggers a sharp cytosolic Ca2+ increase through both Ca2+ release and Ca2+ influx. The change in cytosolic Ca2+ is transduced finally into inhibition of bone resorption. It has been shown that a type 2 ryanodine receptor isoform, expressed uniquely in the plasma membrane, functions as a Ca2+ influx channel and possibly as a Ca2+ sensor. Ryanodine receptors are ordinarily Ca2+ release channels that have a microsomal membrane location in a wide variety of eukaryotic cells, including the osteoclasts. However, only recently has it become obvious that ryanodine receptors are also expressed in osteoclast nuclear membranes, at which site they probably gate nucleoplasmic Ca2+ influx. Nucleoplasmic Ca2+ in turn regulates key nuclear processes, including gene expression and apoptosis. Here, we review the potential mechanisms underlying the recognition, movement, and effects of Ca2+ in the osteoclast. We will also speculate on the general biological significance of the unique processes used by the osteoclast to handle high Ca2+ loads during bone resorption.
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Affiliation(s)
- M Zaidi
- Center for Skeletal Aging and Osteoporosis, Geriatric Medicine and Extended Care Service, Philadelphia VA Medical Center, PA 19104, USA
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Zaidi M, Adebanjo OA, Moonga BS, Sun L, Huang CL. Emerging insights into the role of calcium ions in osteoclast regulation. J Bone Miner Res 1999; 14:669-74. [PMID: 10320514 DOI: 10.1359/jbmr.1999.14.5.669] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Osteoclasts are exposed to unusually high, millimolar, Ca2+ concentrations and can "sense" changes in their ambient Ca2+ concentration during resorption. This results in a sharp cystolic Ca2+ increase through both Ca2+ release and Ca2+ influx. The rise in cystolic Ca2+ is transduced finally into an inhibition of bone resorption. We have shown that a type 2 ryanodine receptor isoform, expressed uniquely in the osteoblast plasma membrane, functions as a Ca2+ influx channel, and possibly as a Ca2+ sensor. Ryanodine receptors are ordinarily microsomal membrane Ca2+ release channels. They have only recently been shown to be expressed a other sites, including nuclear membranes. At the latter site, ryanodine receptors gate nucleoplasmic Ca2+ influx. Nucleoplasmic Ca2+, in turn, regulates key nuclear processes, including gene expression and apoptosis. Here, we review potential mechanisms underlying the recognition, movement, and actions of Ca2+ in the osteoclast.
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Affiliation(s)
- M Zaidi
- Center for Skeletal Aging and Osteoporosis, Geriatric Medicine and Extended Care Service, VA Medical Center, Philadelphia, Pennsylvania 19104, USA
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11
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Brown EM, Vassilev PM, Quinn S, Hebert SC. G-protein-coupled, extracellular Ca(2+)-sensing receptor: a versatile regulator of diverse cellular functions. VITAMINS AND HORMONES 1999; 55:1-71. [PMID: 9949679 DOI: 10.1016/s0083-6729(08)60933-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- E M Brown
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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12
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Jan CR, Ho CM, Wu SN, Huang JK, Tseng CJ. Mechanism of lanthanum inhibition of extracellular ATP-evoked calcium mobilization in MDCK cells. Life Sci 1998; 62:533-40. [PMID: 9464465 DOI: 10.1016/s0024-3205(97)01149-1] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We have studied the effects of La3+ on ATP-evoked rises in intracellular calcium levels ([Ca2+]i) measured by fura-2 fluorimetry in Madin Darby canine kidney (MDCK) cells. ATP evoked [Ca2+]i rises dose-dependently with an EC50 of 2.5 microM. The trigger for the Ca2+ signal was a release of Ca2+ from the inositol-1,4,5-trisphosphate (IP3)-sensitive stores because the signal was completely blocked by pretreatment with the endoplasmic reticulum (ER) Ca2+ pump inhibitor thapsigargin (TG) or the phospholipase C (PLC) inhibitor U73122. Both the peak height and area under the curve of 10 microM ATP-evoked Ca2+ signal was reduced by approximately 50% by extracellular Ca2+ removal, suggesting that ATP induced capacitative Ca2+ entry. La3+ inhibited the ATP-evoked Ca2+ signal dose-dependently when added before or after ATP. Pretreatment of 0.1 mM La3+ inhibited approximately 90% of the Ca2+ signal induced by 10 microM ATP. The mechanisms underlying the La3+ inhibition appear to involve not only block of capacitative Ca2+ entry but also interference with ATP binding to the ATP receptors.
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Affiliation(s)
- C R Jan
- Department of Medical Education and Research, Veterans General Hospital-Kaohsiung, National Sun Yat-Sen University, Taiwan, ROC.
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Nichols KG, Puleo DA. Effect of metal ions on the formation and function of osteoclastic cells in vitro. JOURNAL OF BIOMEDICAL MATERIALS RESEARCH 1997; 35:265-71. [PMID: 9135175 DOI: 10.1002/(sici)1097-4636(199705)35:2<265::aid-jbm14>3.0.co;2-g] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
To determine if metal ions play a contributing role in loosening of orthopedic implants, the present work investigated whether sublethal concentrations of ions affect the formation and function of osteoclasts in vitro. Rat bone marrow cells were cultured on slices of devitalized bone and in the presence of ions associated with Co-Cr-Mo and Ti-6A1-4V alloys for up to four weeks. Cultures were assayed for total intracellular protein, used as measure of cell growth, and resorption activity of osteoclastic cells derived from hematopoietic stem cells was quantified using image analysis. Although Co2+ caused delayed toxicity not previously observed during short-term experiments, none of the other ions affected cell proliferation, indicating that the chosen concentrations were sublethal. In general, exposure of bone marrow cultures to ions caused either a decrease or no change in the total area of bone resorption. A decrease in the number of resorption pits formed by osteoclastic cells was primarily responsible for the decrease in total amount of resorption. Therefore, even though cells continued to grow over the entire culture period, less osteoclastic activity was observed. Findings indicate that if metal ions play a role in periprosthetic pathology, they may contribute to implant failure by impairing bone repair while allowing fibrous tissue formation following debris-induced osteolysis.
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Affiliation(s)
- K G Nichols
- Center for Biomedical Engineering, University of Kentucky, Lexington 40506-0070, USA
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14
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Ritchie CK, Strei TA, Maercklein PB, Fitzpatrick LA. Antithetic effects of ryanodine and ruthenium red on osteoclast-mediated bone resorption and intracellular calcium concentrations. J Cell Biochem 1995; 59:281-9. [PMID: 8904321 DOI: 10.1002/jcb.240590216] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In the process of bone remodeling, osteoclasts are responsible for resorption of bone. High levels of intracellular calcium decrease the bone resorbing activity of osteoclasts and increase detachment of osteoclasts from the bone surface. The regulatory role of intracellular calcium in bone resorption is not clearly understood. To understand this phenomenon, we studied the effects of the intracellular calcium modulators ryanodine and ruthenium red on bone resorption using the disaggregated osteoclast pit assay. Changes in intracellular calcium concentrations after treatment with these compounds were detected with the fluoroprobe fura2. With ryanodine, a significant, dose-dependent decrease in bone resorption was detected. This inhibition of bone resorption was reversible upon the removal of ryanodine. Ryanodine increased intracellular calcium concentrations, suggesting that the mechanism of inhibition by ryanodine was via alterations in intracellular stores of calcium. After treatment with ruthenium red, osteoclasts resorbed significantly more bone compared to vehicle-treated cells. This increase in bone resorption correlated with a decrease in intracellular calcium concentrations. The addition of parathyroid hormone or ruthenium red to osteoclast cultures containing ryanodine did not attenuate the decrease in bone resorption caused by ryanodine, suggesting that the mechanism of ryanodine inhibition of bone resorption may involve the "locking" of a calcium channel in an open position.
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Affiliation(s)
- C K Ritchie
- Endocrine Research Unit, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA
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15
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Zaidi M, Moonga BS, Huang CL, Towhidul Alam AS, Shankar VS, Pazianas M, Eastwood JB, Datta HK, Rifkin BR. The effect of tetracyclines on quantitative measures of osteoclast morphology. Biosci Rep 1993; 13:175-82. [PMID: 8268425 DOI: 10.1007/bf01149962] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
We report the effects of the tetracycline analogues 4-dedimethylaminotetracycline (CMT-1) and minocycline on osteoclast spreading and motility. Both agents influenced the morphometric descriptor of cell spread area, rho, producing cellular retraction or an R effect (half-times: 30 and 44 minutes for CMT-1 and minocycline, respectively). At the concentrations employed, the tetracycline-induced R effects were significantly slower than, but were qualitatively similar to, those resulting from Ca2+ "receptor" activation through the application of 15 mM-[Ca2+] (slopes: -1.25, -0.18, and -4.40/minute for 10 mg/l-[CMT-1], 10 mg/l-[minocycline] and 15 mM-[Ca2+], respectively). In contrast, the same tetracycline concentrations did not influence osteoclast margin ruffling activity as described by mu, a motility descriptor known to be influenced by elevations of cellular cyclic AMP. Thus, the tetracyclines exert morphometric effects comparable to changes selectively activated by occupancy of the osteoclast Ca2+ "receptor" which may act through an increase in cytosolic [Ca2+].
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Affiliation(s)
- M Zaidi
- Bone Research Unit, St. George's Hospital Medical School, London, UK
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16
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Alam AS, Huang CL, Blake DR, Zaidi M. A hypothesis for the local control of osteoclast function by Ca2+, nitric oxide and free radicals. Biosci Rep 1992; 12:369-80. [PMID: 1290801 DOI: 10.1007/bf01121500] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Several important conclusions have recently emerged from in vitro studies on the resorptive cell of bone, the osteoclast. First, it has been established that osteoclast function is modulated locally, by changes in the local concentration of Ca2+ caused by hydroxyapatite dissolution. It is thought that activation by Ca2+ of a surface membrane Ca2+ receptor mediates these effects, hence providing a feedback control. Second, a number of molecules produced locally by the endothelial cell, with which the osteoclast is in intimate contact, have been found to affect bone resorption profoundly. For instance, the autocoid nitric oxide strongly inhibits bone resorption. Finally, reactive oxygen species have been found to aid bone resorption and enhance osteoclastic activity directly. Here, we will attempt to integrate these control mechanisms into a unified hypothesis for the local control of bone resorption.
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Affiliation(s)
- A S Alam
- Department of Cellular and Molecular Sciences, St. George's Hospital Medical School, London, U.K
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