• Imaging Science in Dentistry
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• v.39 no.3
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• pp.121-132
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• 2009

Purpose : To investigate the effects of 2-deoxy-D-glucose (2-DG) and quercetin (QCT) on gene expression of bone sialoprotein (BSP) and osteocalcin (OC) during the differentiation in irradiated MC3T3-E1 osteoblastic cells. Materials and Methods : When MC3T3-E1 osteoblastic cells had reached 70-80% confluence, cultures were transferred to a differentiating medium supplemented with 5 mM 2-DG or $10{\mu}M$ QCT, and then irradiated with 2, 4, 6, and 8 Gy. At various times after irradiation, the cells were analyzed for the synthesis of type I collagen, and expression of BSP and OC. Results : The synthesis of type I collagen in cells exposed to 2 Gy of radiation in the presence of 2-DG or QCT showed no significant difference compared with the control group within 15 days post-irradiation. When the cells were irradiated with 8 Gy, 2-DG facilitated the irradiation mediated decrease of type I collagen synthesis, whereas such decrease was inhibited by treating with QCT. During MC3T3-E1 osteoblastic cell differentiation, the mRNA expression of BSP and OC showed the peak value at 14 days and 21 days, respectively. 2-DG or QCT treatment alone decreased the level of BSP mRNA, but increased the OC mRNA level only at early time of differentiation (day 7). In the cells irradiated with 2, 4, 8 Gy, the mRNA expression of BSP and OC decreased at 7 days after the irradiation. The cells were treated with various dose of radiation in the presence of 2-DG or QCT, the mRNA level of both BSP and OC increased although this increase was observed at low dose of radiation (2 Gy) and at the early stage of differentiation. However, when the cells were exposed to 4, 6, or 8 Gy, the increase of BSP and OC mRNAs was detected only in cells co-incubated with QCT. Conclusion : This study demonstrates that 2-DG and QCT affect differently the expression of bone formation related factors, type I collagen, BSP, and OC in the irradiated MC3T3-E1 osteoblasic cells, according to the dose of radiation and the times of differentiation. Overall, the present findings suggest that 2-DG and QCT could have the regulatory roles as radiation-sensitizer and -protector, respectively.

• Preventive Nutrition and Food Science
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• v.12 no.1
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• pp.1-6
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• 2007

Colostrum basic proteins (CBP) (MW 1$\sim$30 kDa) were isolated from bovine colostrum using a series of ultrafiltration processes and their effects on osteoblast cell proliferation and bone metabolism were investigated in cell line and animal models. Treatments with CBP (1, 10, 100 $\mu$g/mL) dose-dependently increased cell proliferation of osteoblastic MC3T3 cells. Alkaline phosphatase activity, a marker of osteoblastic phenotype, in the cells was also increased after treatments with CBP in a dose-dependent manner. Significant increases in bone density were observed in femur of ovariectomized rats which were fed a diet with 1% and 10% CBP, compared to rats fed a normal diet. These results suggest that CBP may increase bone mass and density and be useful for the prevention of bone-related diseases.

• Journal of Society of Preventive Korean Medicine
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• v.12 no.2
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• pp.197-206
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• 2008

The inhibition of osteoblast by glucocorticoid is recognized as its action mechanism of decreased bone formation. In this study, the effect of JY, Jahyulyangkeuntang, on the differentiation and mineralization of osteoblastic cells was investigated in the presence of dexamethasone. The cell counting, enzyme activity assay, MTT assay, collagen content assay were done to determine the cell proliferation, alkaline phosphatase(ALP) activity, bone martrix production, and cell apoptosis. JY enhanced the cell proliferation after the culture for 10 days. ALP activity and total protein synthesis, and intracellular collagen synthesis were increased when the cells were treated with JY. And JY restored calvarial cell function decreased by dexamethasone.

• International Journal of Oral Biology
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• v.44 no.1
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• pp.1-7
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• 2019

Osteoporosis is a common disease characterized by bone mass reduction, leading to an increased risk of bone fracture, and it is caused by an imbalance of osteoblastic bone formation and osteoclastic bone resorption. Current osteoporosis drugs aim to reduce the risk of bone fracture, either by increasing osteoblastic bone formation or decreasing osteoclastic bone resorption. However, osteoblasts and osteoclasts are closely coupled, such that any reagent altering the differentiation or activity of one eventually affects the other. This tight coupling between osteoblasts and osteoclasts not only limits the therapeutic efficacy but also threatens the safety of osteoporosis drugs. This review will discuss the biological mechanisms of action of currently approved medications for osteoporosis treatment, focusing on the osteoblast-osteoclast coupling.

• Proceedings of the Korean Nutrition Society Conference
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• 2003.10a
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• pp.101-101
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• 2003

• Journal of Physiology & Pathology in Korean Medicine
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• v.22 no.4
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• pp.802-809
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• 2008

Gamijangsing-tang (GMJST) has been used for treatment of bone formation in traditional korean medicine. The purpose of this study is to examine effects of GMJST on bone metabolism. The effects on the osteoblasts were determined by measuring (1) cell proliferation, (2) alkaline phosphatase (ALP) activity, (3) osteoprotegerin (OPG) secretion. (4) The morphologic changes of cells were observed by light microscopy and electron microscopy. Mineralization of calcium was determined by quantitative alizarin red-S assay and mineralization of phosphate was observed by von kossa staining. The morphologic changes of mineralization on the cells were observed by transmission electron microscopy (TEM). The effects on the osteoclast were investigated by tartrate-resistant acid phosphatase (TRAP) staining. Following results were obtained: Celluar activity of osteoblastic cells (MG-63) was significantly increased in 10-5 of dilution of GMJST. ALP and OPG activity of osteoblastic cells were increased in GMJST than normal MG-63 cell. Mineralization of osteoblastic cells were increased in GMJST than normal MG-63 cell. The activity of osteoclast cells (RAW 264.7) was significantly decreased in GMJST than normal MG-63 cell. From the results, GMJST stimulated the proliferation and mineralization of bone-forming osteoblast and inhibited by bone- lysis osteoclast.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.28 no.6
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• pp.549-558
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• 2006

During distraction osteogenesis, the angiogenic activity is crucial factor in the new bone formation. The aim of this study was to detect the autocrine growth activity in the cellular components of the distracted periosteum with observation of the expression of vascular endothelial growth factor (VEGF) and its receptors following the mandibular distraction osteogenesis. Unilateral mandibular distraction (0.5 mm twice per day for 10 days) was performed in six mongrel dogs. Two animals were sacrificed at 7, 14, and 28 days after completion of distraction, respectively. The distracted lingual periosteum was harvested and processed for immunohistochemical examinations. After then, we observed the expression of VEGF, Flt-1 (VEGFR-1), and Flk-1 (VEGFR-2) in the osteoblasts and immature mesenchymal cells of the distracted periosteum. At 7 days after distraction, the expression of VEGF and its receptors were significantly increased in the cellular components of the distracted periosteum. Up to 14 days following distraction, the increased expressions were maintained in the osteoblastic cells. At 28 days after distraction, the expression of VEGF and its receptors decreased, but VEGF was still expressed weak or moderate in the osteoblastic cells of distracted periosteum. The expression pattern of VEGF and its receptors shown here suggested that VEGF play an important role in the osteogenesis, and these osteoblastic cell-derived VEGF might act as autocrine growth factor during distraction osteogenesis. In the other word, the cellular components in the distracted periosteum, such as osteoblasts and immature mesenchymal cells, might have autocrine growth activity during distraction osteogenesis.

• The Korean Journal of Physiology and Pharmacology
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• v.6 no.3
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• pp.165-169
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• 2002

We have previously demonstrated that phytoestrogens isolated from safflower seeds significantly attenuated bone loss in ovariectomized rats, and directly stimulated proliferation and differentiation of cultured osteoblastic cells. In an attempt to elucidate underlying cellular mechanisms, in the present study we investigated effects of $17{\beta}-estradiol\;(E_2)$ and phytoestrogens such as matairesinol and acacetin, a type of lignan and flavonoid, respectively, on activation of mitogen activated protein (MAP) kinases, extracellular signal-regulated kinase 1 (ERK1) and ERK2, in cultured osteoblastic ROS 17/2.8 cells. Western blot analysis with anti-MAP kinase antibody showed that a wide range concentrations $(10^{-14}\;to\;10^{-6}\;M)\;of\;E_2$ as well as both phytoestrogens induced rapid and transient activation of ERK1/2 through phosphorylation within minutes. Maximum activation of MAP kinases by $E_2$ and phytoestrogens were observed at 10 and 15 min, respectively. $E_2-induced$ phosphorylation of ERK1/2 returned to the control level at 30 min, whereas phytoestrogen-induced phosphorylation was maintained at high level until 30 min. PD-98059, a highly selective inhibitor of MAP kinase, prevented phosphorylation of ERK1/2 in the cells treated either with $E_2$ or phytoestrogens. To examine a possible involvement of estrogen receptor in the activation process of MAP kinase, Western blot analysis was performed in the presence and absence of the estrogen receptor antagonists, ICI 182,780 and tamoxifen. These antagonists blocked MAP kinase phosphorylation induced not only by $E_2,$ but also by the phytoestrogens. To the best our knowledge, this study is the first to demonstrate that phytoestrogens such as flavonoid and lignan extracted from safflower seeds produce a rapid activation of MAP kinase, at least partially via membrane estrogen receptor of the cultured osteoblastic cells.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.19 no.1
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• pp.69-87
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• 1989

It is well known that the glucocorticoid induces osteoporosis by suppression of the osteoblast, but its effect on the osteoclast hRS some controversy whether it activates or suppresses the osteoclast. If the calcitonin, which is known to suppress the osteoclast, prevents the osteoporosis by glucocorticoid, then the suppression of the osteoclast by the glucocorticoid is not so significant. And if the calcitonin increases the osteoblastic activity, Tc-99m MDP uptake will be increased in spite of the glucocorticoid effect on the osteoblast. The immobilization operation was performed to the right leg of male Wistar rats weighing about 200gm. each. For 16 weeks after operation, rats were injected glucocorticoid alone or glucocorticoid anci calcitonin. The bone density was measured by means of photodensitometry under reference aluminum step wedge and Tc-99m MDP uptake was available to the index of the osteoblastic activity. 1. The bone density of femora! head was markedly reduced than that of femoral shaft following ration of cancellous and cortical components in both site. 2. Glucocorticoid caused decrease in bone density of spine and femur, md there is significantly increase of it when medication of glucocorticoid and calcitonin injection simultaneously than that of glucocorticoid. 3. Tc-99m MDP uptake was revealed significant reduction in medication of glucocorticoid but increase in gi;.:cocorticoid and calcitonin injection simultaneously in later experimental period. 4. There wail, a slight reduction in plasma osteocalcin in medication of glucocorticoid through experimental periods and an increase in its value in case of giving glucocorticoid and calcitonin simultaneously in later experimental period. From these results, we suggest that osteoporosis by immobilization is more pronounced by glucocorticoid hormone and osteoporosis induced by immobilization and glucocorticoid use is prevented by calcitonin administration with increasing osteoblastic activity.

• Molecules and Cells
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• v.41 no.3
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• pp.234-243
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• 2018

In recent years, the interest towards the relationship between incretins and bone has been increasing. Previous studies have suggested that glucagon-like peptide-1 (GLP-1) and its receptor agonists exert beneficial anabolic influence on skeletal metabolism, such as promoting proliferation and differentiation of osteoblasts via entero-osseous-axis. However, little is known regarding the effects of GLP-1 on osteoblast apoptosis and the underlying mechanisms involved. Thus, in the present study, we investigated the effects of liraglutide, a glucagon-like peptide-1 receptor agonist, on apoptosis of murine MC3T3-E1 osteoblastic cells. We confirmed the presence of GLP-1 receptor (GLP-1R) in MC3T3-E1 cells. Our data demonstrated that liraglutide inhibited the apoptosis of osteoblastic MC3T3-E1 cells induced by serum deprivation, as detected by Annexin V/PI and Hoechst 33258 staining and ELISA assays. Moreover, liraglutide upregulated Bcl-2 expression and downregulated Bax expression and caspase-3 activity at intermediate concentration (100 nM) for maximum effect. Further study suggested that liraglutide stimulated the phosphorylation of AKT and enhanced cAMP level, along with decreased phosphorylation of $GSK3{\beta}$, increased ${\beta}-catenin$ phosphorylation at Ser675 site and upregulated nuclear ${\beta}-catenin$ content and transcriptional activity. Pretreatment of cells with the PI3K inhibitor LY294002, PKA inhibitor H89, and siRNAs GLP-1R, ${\beta}-catenin$ abrogated the liraglutide-induced activation of cAMP, AKT, ${\beta}-catenin$, respectively. In conclusion, these findings illustrate that activation of GLP-1 receptor by liraglutide inhibits the apoptosis of osteoblastic MC3T3-E1 cells induced by serum deprivation through $cAMP/PKA/{\beta}-catenin$ and $PI3K/Akt/GSK3{\beta}$ signaling pathways.