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Hu B, Chen Y, Li Y, Deng C, Niu Y, Hu Z, Li Y, Sun S, Huang Y, Deng X, Wei Y. Substrate-Mediated Regulation of Src Expression Drives Osteoclastogenesis Divergence. Genes (Basel) 2024; 15:1217. [PMID: 39336808 PMCID: PMC11431296 DOI: 10.3390/genes15091217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2024] [Revised: 09/08/2024] [Accepted: 09/14/2024] [Indexed: 09/30/2024] Open
Abstract
BACKGROUND/OBJECTIVES Glass, bone, and dentin are commonly applied substrates for osteoclast cultures; however, the impact of these substrates on osteoclastogenesis remains underexplored. This study aimed to address a significant gap in understanding how different substrates influence the process of osteoclastogenesis. METHODS RAW 264.7 cells were cultured and induced with RANKL on glass, bone, and dentin slides. Histological and molecular techniques were used to identify patterns and differences in osteoclast behavior on each substrate. RESULTS Osteoclasts cultured on glass slides possessed the greatest number of nuclei and the highest expression levels of ACP5 (TRAP) and CTSK, with osteoclasts on bone and dentin slides displaying progressively lower levels. Src expression was also most pronounced in osteoclasts on glass slides, with decreased levels observed on bone and dentin. This variation in Src expression likely contributed to differences in cytoskeletal remodeling and oxidative phosphorylation (OXPHOS), resulting in substrate-dependent divergences in osteoclastogenesis. CONCLUSIONS Glass slides were the most favorable substrate for inducing osteoclastogenesis, while bone and dentin slides were less effective. The substrate-induced expression of Src played a fundamental role in shaping the phenotypic divergence of osteoclasts. These insights fill important knowledge gaps and have significant implications for the development and selection of in vitro models for bone-related diseases and drug screening platforms.
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Affiliation(s)
- Bo Hu
- Department of Geriatric Dentistry, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Beijing 100081, China; (B.H.); (Y.C.); (Y.L.); (Y.N.); (Z.H.); (Y.L.); (Y.H.); (X.D.)
- Department of Prosthodontics, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Beijing 100081, China
| | - Yiming Chen
- Department of Geriatric Dentistry, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Beijing 100081, China; (B.H.); (Y.C.); (Y.L.); (Y.N.); (Z.H.); (Y.L.); (Y.H.); (X.D.)
- Department of Prosthodontics, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Beijing 100081, China
| | - Yuman Li
- Department of Geriatric Dentistry, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Beijing 100081, China; (B.H.); (Y.C.); (Y.L.); (Y.N.); (Z.H.); (Y.L.); (Y.H.); (X.D.)
| | - Chenyu Deng
- Department of Orthodontics, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Beijing 100081, China;
| | - Yuting Niu
- Department of Geriatric Dentistry, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Beijing 100081, China; (B.H.); (Y.C.); (Y.L.); (Y.N.); (Z.H.); (Y.L.); (Y.H.); (X.D.)
- Department of Prosthodontics, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Beijing 100081, China
| | - Zhewen Hu
- Department of Geriatric Dentistry, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Beijing 100081, China; (B.H.); (Y.C.); (Y.L.); (Y.N.); (Z.H.); (Y.L.); (Y.H.); (X.D.)
| | - Yao Li
- Department of Geriatric Dentistry, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Beijing 100081, China; (B.H.); (Y.C.); (Y.L.); (Y.N.); (Z.H.); (Y.L.); (Y.H.); (X.D.)
- Department of Prosthodontics, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Beijing 100081, China
| | - Shiyu Sun
- Department of General Dentistry, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Beijing 100081, China;
| | - Ying Huang
- Department of Geriatric Dentistry, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Beijing 100081, China; (B.H.); (Y.C.); (Y.L.); (Y.N.); (Z.H.); (Y.L.); (Y.H.); (X.D.)
| | - Xuliang Deng
- Department of Geriatric Dentistry, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Beijing 100081, China; (B.H.); (Y.C.); (Y.L.); (Y.N.); (Z.H.); (Y.L.); (Y.H.); (X.D.)
| | - Yan Wei
- Department of Geriatric Dentistry, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Beijing 100081, China; (B.H.); (Y.C.); (Y.L.); (Y.N.); (Z.H.); (Y.L.); (Y.H.); (X.D.)
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Li S, Liu G, Hu S. Osteoporosis: interferon-gamma-mediated bone remodeling in osteoimmunology. Front Immunol 2024; 15:1396122. [PMID: 38817601 PMCID: PMC11137183 DOI: 10.3389/fimmu.2024.1396122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Accepted: 04/26/2024] [Indexed: 06/01/2024] Open
Abstract
As the world population ages, osteoporosis, the most common disease of bone metabolism, affects more than 200 million people worldwide. The etiology is an imbalance in bone remodeling process resulting in more significant bone resorption than bone remodeling. With the advent of the osteoimmunology field, the immune system's role in skeletal pathologies is gradually being discovered. The cytokine interferon-gamma (IFN-γ), a member of the interferon family, is an important factor in the etiology and treatment of osteoporosis because it mediates bone remodeling. This review starts with bone remodeling process and includes the cellular and key signaling pathways of bone remodeling. The effects of IFN-γ on osteoblasts, osteoclasts, and bone mass are discussed separately, while the overall effects of IFN-γ on primary and secondary osteoporosis are summarized. The net effect of IFN-γ on bone appears to be highly dependent on the environment, dose, concentration, and stage of cellular differentiation. This review focuses on the mechanisms of bone remodeling and bone immunology, with a comprehensive discussion of the relationship between IFN-γ and osteoporosis. Finding the paradoxical balance of IFN-γ in bone immunology and exploring the potential of its clinical application provide new ideas for the clinical treatment of osteoporosis and drug development.
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Affiliation(s)
- Siying Li
- The Orthopaedic Center, The First People’s Hospital of Wenling, Taizhou University Affiliated Wenling Hospital, Wenling, Zhejiang, China
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, Hunan, China
| | - Gang Liu
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, Hunan, China
| | - Siwang Hu
- The Orthopaedic Center, The First People’s Hospital of Wenling, Taizhou University Affiliated Wenling Hospital, Wenling, Zhejiang, China
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The NOD- scid IL2rγnull Mouse Model Is Suitable for the Study of Osteoarticular Brucellosis and Vaccine Safety. Infect Immun 2019; 87:IAI.00901-18. [PMID: 30936160 DOI: 10.1128/iai.00901-18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 03/27/2019] [Indexed: 01/20/2023] Open
Abstract
Osteoarticular brucellosis is the most common complication in Brucella-infected humans regardless of age, sex, or immune status. The mechanism of bone destruction caused by Brucella species remained partially unknown due to the lack of a suitable animal model. Here, to study this complication, we explored the suitability of the use of the NOD-scid IL2rγnull mouse to study osteoarticular brucellosis and examined the potential use of this strain to evaluate the safety of live attenuated vaccine candidates. Mice were inoculated intraperitoneally with a single dose of 1 × 104, 1 × 105, or 1 × 106 CFU of B. abortus S19 or the vaccine candidate B. abortus S19ΔvjbR and monitored for the development of side effects, including osteoarticular disease, for 13 weeks. Decreased body temperature, weight loss, splenomegaly, and deformation of the tails were observed in mice inoculated with B. abortus S19 but not in those inoculated with S19ΔvjbR Histologically, all S19-inoculated mice had a severe dose-dependent inflammatory response in multiple organs. The inflammatory response at the tail was characterized by the recruitment of large numbers of neutrophils, macrophages, and osteoclasts with marked bone destruction. These lesions histologically resembled what is typically observed in Brucella-infected patients. In contrast, mice inoculated with B. abortus S19ΔvjbR did not show significant bone changes. Immunofluorescence, in situ hybridization, and confocal imaging demonstrated the presence of Brucella at the sites of inflammation, both intra- and extracellularly, and large numbers of bacteria were observed within mature osteoclasts. These results demonstrate the potential use of the NOD-scid IL2rγnull mouse model to evaluate vaccine safety and further study osteoarticular brucellosis.
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Kajita T, Ariyoshi W, Okinaga T, Mitsugi S, Tominaga K, Nishihara T. Mechanisms involved in enhancement of osteoclast formation by activin-A. J Cell Biochem 2018; 119:6974-6985. [PMID: 29737562 DOI: 10.1002/jcb.26906] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 03/28/2018] [Indexed: 12/23/2022]
Abstract
Several growth factors in bone tissues are reported to be associated with osteoclastogenesis. Activin-A, a member of the transforming growth factor-β (TGF-β) family is known to be present in bone tissues and an important regulator in osteoclastogenesis with SMAD-mediated signaling being crucial for inducing osteoclast differentiation. In the present study, we examined the effect and underlying mechanisms of activin-A on osteoclast formation in vitro culture systems. Activin-A enhanced osteoclast formation in both mouse bone marrow cells and monocyte/macrophage cell line RAW 264.7 cells induced by receptor activator of nuclear factor kappa B (NF-κB) ligand (RANKL) and/or macrophage stimulating factor (M-CSF). We also found that activin-A stimulated bone resorption and actin ring formation induced by RANKL and/or M-CSF. Furthermore, activin-A enhanced RANKL-induced expression of nuclear factor of activated T cell cytoplasmic 1 (NFATc1), a key regulator of osteoclastogenesis, thereby increasing osteoclastogenesis-related marker gene expression, including tartrate-resistant acid phosphatase, osteoclast stimulatory transmembrane protein, and cathepsin K. Blockage of receptor binding by follistatin, an activing-binding protein suppressed the activin-A-mediated stimulation of NFATc1. In addition, activin-A increased RANKL-induced c-fos expression without significantly affecting the NF-κB and mitogen-activated protein kinase (MAPK) signaling pathway. Pre-treatment of the cells with a specific inhibitor of SMAD2/3 attenuated the activin-A-induced expression of NFATc1 and co-immunoprecipitation assay revealed that treatment with activin-A increased physical interaction of phosphorylated-c-fos and phosphorylated-SMAD2 protein induced by RANKL. These results suggest that activin-A enhances RANKL-induced osteoclast formation mediated by interaction of c-fos and smad2/3.
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Affiliation(s)
- Tomonari Kajita
- Division of Infections and Molecular Biology, Department of Health Promotion, Kyushu Dental University, Kitakyushu, Fukuoka, Japan.,Division of Oral and Maxillofacial Surgery, Department of Science and Physical Functions, Kyushu Dental University, Kitakyushu, Fukuoka, Japan
| | - Wataru Ariyoshi
- Division of Infections and Molecular Biology, Department of Health Promotion, Kyushu Dental University, Kitakyushu, Fukuoka, Japan
| | - Toshinori Okinaga
- Division of Infections and Molecular Biology, Department of Health Promotion, Kyushu Dental University, Kitakyushu, Fukuoka, Japan
| | - Sho Mitsugi
- Division of Oral and Maxillofacial Surgery, Department of Science and Physical Functions, Kyushu Dental University, Kitakyushu, Fukuoka, Japan
| | - Kazuhiro Tominaga
- Division of Oral and Maxillofacial Surgery, Department of Science and Physical Functions, Kyushu Dental University, Kitakyushu, Fukuoka, Japan
| | - Tatsuji Nishihara
- Division of Infections and Molecular Biology, Department of Health Promotion, Kyushu Dental University, Kitakyushu, Fukuoka, Japan
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Fowler TW, Kamalakar A, Akel NS, Kurten RC, Suva LJ, Gaddy D. Activin A inhibits RANKL-mediated osteoclast formation, movement and function in murine bone marrow macrophage cultures. J Cell Sci 2015; 128:683-94. [PMID: 25609708 PMCID: PMC4327386 DOI: 10.1242/jcs.157834] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2014] [Accepted: 12/12/2014] [Indexed: 12/26/2022] Open
Abstract
The process of osteoclastic bone resorption is complex and regulated at multiple levels. The role of osteoclast (OCL) fusion and motility in bone resorption are unclear, with the movement of OCL on bone largely unexplored. RANKL (also known as TNFSF11) is a potent stimulator of murine osteoclastogenesis, and activin A (ActA) enhances that stimulation in whole bone marrow. ActA treatment does not induce osteoclastogenesis in stroma-free murine bone marrow macrophage cultures (BMM), but rather inhibits RANKL-induced osteoclastogenesis. We hypothesized that ActA and RANKL differentially regulate osteoclastogenesis by modulating OCL precursors and mature OCL migration. Time-lapse video microscopy measured ActA and RANKL effects on BMM and OCL motility and function. ActA completely inhibited RANKL-stimulated OCL motility, differentiation and bone resorption, through a mechanism mediated by ActA-dependent changes in SMAD2, AKT1 and inhibitor of nuclear factor κB (IκB) signaling. The potent and dominant inhibitory effect of ActA was associated with decreased OCL lifespan because ActA significantly increased activated caspase-3 in mature OCL and OCL precursors. Collectively, these data demonstrate a dual action for ActA on murine OCLs.
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Affiliation(s)
- Tristan W Fowler
- Departments of Physiology & Biophysics, University of Arkansas for Medical Sciences, College of Medicine, Little Rock, AR 72205 USA
| | - Archana Kamalakar
- Departments of Physiology & Biophysics, University of Arkansas for Medical Sciences, College of Medicine, Little Rock, AR 72205 USA Orthopaedic Surgery, Center for Orthopaedic Research, University of Arkansas for Medical Sciences, College of Medicine, Little Rock, AR 72205 USA
| | - Nisreen S Akel
- Departments of Physiology & Biophysics, University of Arkansas for Medical Sciences, College of Medicine, Little Rock, AR 72205 USA Orthopaedic Surgery, Center for Orthopaedic Research, University of Arkansas for Medical Sciences, College of Medicine, Little Rock, AR 72205 USA
| | - Richard C Kurten
- Departments of Physiology & Biophysics, University of Arkansas for Medical Sciences, College of Medicine, Little Rock, AR 72205 USA
| | - Larry J Suva
- Departments of Physiology & Biophysics, University of Arkansas for Medical Sciences, College of Medicine, Little Rock, AR 72205 USA Orthopaedic Surgery, Center for Orthopaedic Research, University of Arkansas for Medical Sciences, College of Medicine, Little Rock, AR 72205 USA
| | - Dana Gaddy
- Departments of Physiology & Biophysics, University of Arkansas for Medical Sciences, College of Medicine, Little Rock, AR 72205 USA Orthopaedic Surgery, Center for Orthopaedic Research, University of Arkansas for Medical Sciences, College of Medicine, Little Rock, AR 72205 USA
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Fu Y, Gu J, Wang Y, Yuan Y, Liu X, Bian J, Liu ZP. Involvement of the Ca²⁺ signaling pathway in osteoprotegerin inhibition of osteoclast differentiation and maturation. J Vet Sci 2014; 16:151-6. [PMID: 25549213 PMCID: PMC4483497 DOI: 10.4142/jvs.2015.16.2.151] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 11/12/2014] [Indexed: 01/06/2023] Open
Abstract
The purpose of this study was to determine whether the Ca2+ signaling pathway is involved in the ability of osteoprotegerin (OPG) to inhibit osteoclast differentiation and maturation. RAW264.7 cells were incubated with macrophage colony-stimulating factor (M-CSF) + receptor activator of nuclear factor-κB ligand (RANKL) to stimulate osteoclastogenesis and then treated with different concentrations of OPG, an inhibitor of osteoclast differentiation. The intracellular Ca2+ concentration [Ca2+]i and phosphorylation of Ca2+/calmodulin-dependent protein kinase II (CaMKII) in the different treatment groups were measured by flow cytometry and Western blotting, respectively. The results confirmed that M-CSF + RANKL significantly increased [Ca2+]i and CaMKII phosphorylation in osteoclasts (p < 0.01), and that these effects were subsequently decreased by OPG treatment. Exposure to specific inhibitors of the Ca2+ signaling pathway revealed that these changes varied between the different OPG treatment groups. Findings from the present study indicated that the Ca2+ signaling pathway is involved in both the regulation of osteoclastogenesis as well as inhibition of osteoclast differentiation and activation by OPG.
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Affiliation(s)
- Yingxiao Fu
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China
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Kitazawa R, Kitazawa S. Methylation Status of a Single CpG Locus 3 Bases Upstream of TATA-Box of Receptor Activator of Nuclear Factor-κB Ligand (RANKL) Gene Promoter Modulates Cell- and Tissue-Specific RANKL Expression and Osteoclastogenesis. Mol Endocrinol 2007; 21:148-58. [PMID: 17008384 DOI: 10.1210/me.2006-0205] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Receptor activator of nuclear factor-kappaB ligand (RANKL) expression is tissue specific and limited to certain subsets of T-lymphocytes and stromal/osteoblastic cells. Even among osteoblasts, RANKL is expressed on about 20% of osteoblasts of the normal mouse. To clarify the mechanism of population-specific RANKL expression, we analyzed the effect of CpG methylation on its transcription, mRNA and protein expression as well as on osteoclastogenesis. Subpopulations of ST2 cells were used: P9, which expresses RANKL and supports osteoclastogenesis, and P16, which does not. By sodium bisulfite mapping, the rate of CpG methylation of the -65/+350 region, especially of CpG locus no. 1 three bases upstream of the TATA-box, was higher in P16 than in P9 ST2 cells. ChIP and gel shift assay showed that methylated CpG locus no. 1 was a target of MeCP2 binding that, in turn, blocked the binding of the TATA-box binding protein to the TATA-box. In vitro methylation by SssI of the promoter construct reduced its transcriptional activity at the steady state and its response to 1alpha,25(OH)2 vitamin D3. Conversely, treatment with DNA methylase inhibitor, 5-aza-2'-deoxycytidine, significantly restored RANKL expression and osteoclastogenesis in P16 cells. Except for primary cultured osteoblasts, CpG locus no. 1 was frequently methylated in various normal mouse tissues. We propose that the methylation status of the CpG locus three bases upstream of the TATA-box modulates the control of cell- and tissue-specific expression of RANKL gene and osteoclastogenesis. The heterogeneity of stromal/ osteoblastic cells in response to bone-resorbing stimuli may be attributed, in part, to the methylation status of the RANKL gene promoter.
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Affiliation(s)
- Riko Kitazawa
- Division of Molecular Pathology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
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Velich N, Németh Z, Hrabák K, Suba Z, Szabó G. Repair of Bony Defect With Combination Biomaterials. J Craniofac Surg 2004; 15:11-5. [PMID: 14704554 DOI: 10.1097/00001665-200401000-00006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Numerous possibilities are available for the reconstruction of facial bone defects. The materials used to fill such defects must satisfy various requirements. One of the most important is that they must undergo transformation into autologous bone tissue in the process of remodeling. AIM A report is given of the long-term results of augmentations of large bone defects performed with different bone-substitute materials in two patients. PATIENTS AND METHODS In one case, augmentation was carried out with beta-tricalcium phosphate after the removal of a fibromyxoma. In the second case, three large cystic lesions in the mandible of a patient with Gorlin-Goltz syndrome were filled with beta-tricalcium phosphate, with a mixture of beta-tricalcium phosphate and platelet concentrate, or with hydroxyapatite of algal origin. The process of ossification was checked at 6-month intervals by means of clinical, radiologic (orthopantomograms and two-dimensional and three-dimensional computer tomograms), and histologic methods. RESULTS At 1 year after the intervention, the site of the augmentation was in all cases occupied by hard tissue of good quality. With the given imaging procedures, it was difficult to distinguish between the original bone and the region filled with bone-substitute material. The three-dimensional computer tomogram images indicated that the contours and quality of the new bone corresponded with the physiologic and anatomical conditions. The histologic examinations show the remodeling of the bone-substitute materials. DISCUSSION The bone-substitute materials applied in these cases fully satisfied the demands of transformation into bone (remodeling). The speed of remodeling seemed to be the fastest when the mixture of beta-tricalcium phosphate and platelet concentrate was used.
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Affiliation(s)
- Norbert Velich
- Department of Oral and Maxillofacial Surgery, Semmelweis University of Medicine, Budapest, Hungary
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Baecklund M, Pedersen NL, Björkman L, Vahter M. Variation in blood concentrations of cadmium and lead in the elderly. ENVIRONMENTAL RESEARCH 1999; 80:222-30. [PMID: 10094806 DOI: 10.1006/enrs.1998.3895] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
This study aims at characterizing blood concentrations of cadmium (B-Cd) and lead (B-Pb) in a group of 176 men and 248 women, 49-92 years of age (mean 68 years), selected from the Swedish Twin Registry. Metal concentrations were determined using graphite furnace atomic absorption spectrophotometry. B-Cd ranged from 0.05 to 6.8 microg Cd/L (median 0.36 microg Cd/L) and B-Pb from 5.6 to 150 microg Pb/L (median 27 microg Pb/L). As expected, smokers had higher B-Cd than nonsmokers (median 1.3 versus 0.32 microg Cd/L), while B-Pb was not significantly related to smoking habits. Among nonsmokers, women had higher B-Cd than men (median 0.35 versus 0.25 microg Cd/L). In men, but not women, B-Cd increased with age and consequently the gender-related difference in B-Cd was most obvious in the youngest age group. On the other hand, women had lower B-Pb than men (median 24 versus 30 microg Pb/L). In both men and women, B-Pb decreased between 50 and 70 years of age, perhaps reflecting decreased energy intake. In women, the highest B-Pb in the 50-55 years age group is probably related to an increased release of Pb from the skeleton during postmenopausal bone demineralization. After about 70 years, B-Pb tended to increase, which probably is a cohort effect due to much higher Pb exposure 10-30 years ago when leaded gasoline was used.
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Affiliation(s)
- M Baecklund
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
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Masarachia P, Yamamoto M, Leu CT, Rodan G, Duong L. Histomorphometric evidence for echistatin inhibition of bone resorption in mice with secondary hyperparathyroidism. Endocrinology 1998; 139:1401-10. [PMID: 9492077 DOI: 10.1210/endo.139.3.5828] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Echistatin, an RGD-containing peptide, was shown to inhibit the acute calcemic response to exogenous PTH or PTH-related protein (PTH-rP) in thyroparathyroidectomized rats, suggesting that echistatin inhibits bone resorption. In this study: 1) we present histological evidence for echistatin inhibition of bone resorption in mice with secondary hyperparathyroidism, and show that 2) echistatin binds to osteoclasts in vivo, 3) increases osteoclast number, and 4) does not detectably alter osteoclast morphology. Infusion of echistatin (30 microg/kg x min) for 3 days prevented the 2.6-fold increase in tibial cancellous bone turnover and the 36% loss in bone volume, produced by a low calcium diet. At the light microscopy level, echistatin immunolocalized to osteoclasts and megakaryocytes. Echistatin treatment increased osteoclast-covered bone surface by about 50%. At the ultrastructural level, these osteoclasts appeared normal, and the fraction of cells containing ruffled borders and clear zones was similar to controls. Echistatin was found on the basolateral membrane and in intracellular vesicles of actively resorbing osteoclasts. Weak labeling was found in the ruffled border, and no immunoreactivity was detected at the clear zone/bone surface interface. These findings provide histological evidence for echistatin binding to osteoclasts and for inhibition of bone resorption in vivo, through reduced osteoclast efficacy, without apparent changes in osteoclast morphology.
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Affiliation(s)
- P Masarachia
- Department of Bone Biology and Osteoporosis Research, Merck Research Laboratories, West Point, Pennsylvania 19486, USA.
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Abstract
The hallmark of biological mineralization is the precise regulation of mineral deposition in space and time. The cells which produce mineralized tissues are themselves controlled by developmental programs and hormonal signals which result in regulation of gene expression and modulation of protein function. These signals are transduced into changes in enzyme levels and/or activity. Upon activation, cellular enzymes then act to synthesize the organic matrix and process it extracellularly, utilize metabolic energy to transport ions from the blood to the matrix, and to initiate the mineralization cascade. The first enzyme activity described in mineralizing tissues was alkaline phosphatase and it is still the best characterized enzyme in the mineralization process. Yet, important questions about the role of this protein remain unanswered, and it continues to occupy a central focus in mineralized tissue investigation. Other phosphatases, including protein tyrosine phosphatases are important in regulating tyrosine kinase mediated signals. Investigators have now begun to look closely at several groups of kinases which are also important for proper mineralization. As peptide hormones are important modulators of mineralized tissues, protein kinase A has always been presumed to play a key role in phosphorylating intracellular proteins. There is also considerable interest in protein kinase C, as well as tyrosine kinases in mineralized tissue signal transduction. Another group of kinases important in mineralized tissues are the enzymes which phosphorylate the matrix phosphoproteins. Of these, casein kinase II appears to be involved in intracellular and extracellular protein phosphorylation. Several enzymes present in the premineralized matrix are thought to be significant in triggering mineralization. Alkaline phosphatase may act at this level, but new data also suggests that metalloproteases and gelatinases, by modifying or digesting matrix components, may be important in the initiation of calcification.
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Affiliation(s)
- E E Golub
- Biochemistry Department, University of Pennsylvania, School of Dental Medicine, Philadelphia 19104-6003, USA.
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