• Restorative Dentistry and Endodontics
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• v.45 no.2
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• pp.24.1-24.9
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• 2020

Objectives: It is known that bioactive materials interact with the dentin to undergo biomineralization. The exact role of moisture in this interaction is unknown. Here, we investigate the effects of dentin moisture conditions on the dislocation resistance of two bioactive root canal sealers (MTA Fillapex [Angelus Solucoes Odontologicas] and GuttaFlow BioSeal [Colténe/Whaledent AG]) at 3 weeks and 3 months after obturation. Materials and Methods: Mandibular premolars (n = 120) were prepared and randomly divided into 3 groups based on the dentin condition: group 1, dry dentin; group 2, moist dentin; group 3, wet dentin. Each group was divided into 2 subgroups for root canal filling: MTA Fillapex and GuttaFlow BioSeal. Dislocation resistance was evaluated by measuring the push-out bond strength at 3 weeks and 3 months. Failure modes were examined under a stereomicroscope. Data were statistically analyzed by Kruskal-Wallis test with a significance level of 5%. Results: Moist dentin resulted in higher bond strength values for both materials at both time points. This was significantly higher than wet and dry dentin for both the sealers at the 3 months (p < 0.05), while at 3 weeks it was significant only for GuttaFlow Bioseal. The different moisture conditions demonstrated similar trends in their effects on the dislocation resistance of the 2 root canal sealers. Conclusions: The dentin moisture conditions had a significant impact on its interaction with the bioactive materials tested. Maintaining moist dentin, but not dry or wet dentin, may be advantageous before the filling root canals with bioactive sealers.

• Proceedings of the PSK Conference
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• 2001.10a
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• pp.230.3-231
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• 2001

• Bulletin of the Korean Chemical Society
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• v.27 no.1
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• pp.143-146
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• 2006

• Natural Product Sciences
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• v.11 no.2
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• pp.103-108
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• 2005

Bioflavone quercetin is thought to have an important role to inhibit bone loss by affecting osteoclastogenesis and regulating a number of systemic and local factors such as hormones and cytokines. In this study, we examined how quercetin acts on cytokine production and mineralization of osteoblast in the presence of tumor necrosis factor-alpha $(TNF-{\alpha})$ which has been known to play a pivotal role in bone metabolic diseases. Quercetin inhibited $TNF-{\alpha}-induced$ secretion of $IFN-{\gamma}$ and IL-6 in differentiated MC3T3-E1 cells. As indicated by the markers that are characteristics of the osteoblast phenotype, such as alkaline phosphatase (ALP) activity and calcium deposition, quercetin treatment slightly prevented the $TNF-{\alpha}-induced$ dramatic inhibition of differentiation and mineralization of MC3T3-E1 cells. Further, quercetin inhibited the production of nitric oxide induced by $TNF-{\alpha}$ in the cells. Collectively, our findings indicate that quercetin inhibites $TNF-{\alpha}-induced$ secretion of inflammatory cytokines in differentiated MC3T3-E1 cells without any cytotoxic effects.

• Archives of Pharmacal Research
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• v.24 no.4
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• pp.270-275
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• 2001

Bioisostere approach has been shown to be useful to augment potency or to modify certain physiological properties of a lead compound. Based upon well documented bioisosterism, an isosteric replacement of benzene ring of 4-hydroxy-2-quinolone compound (L-695902) with a thiophene moiety was carried out to prepare the title compounds, 4-hydroxy-6-oxo-6,7-dihydro-thieno[2,3-b] pyrimidines 15. The resulting bioisosteric compounds 15 were evaluated for their antagonistic activity (birding assay) for NMDA receptor glycine site.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.263-267
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• 2001

The changes of interfacial properties and microfailure degradation mechanisms of bioabsorbable composites with hydrolysis were investigated using micromechanical test and acoustic emission (AE). As hydrolysis time increased, the tensile strength, the modulus and the elongation of PEA and bioactive glass fibers decreased, whereas those of chitosan fiber changed little. Interfacial shear strength (IFSS) of bioactive glass fiber/poly-L-lactide (PLLA) composite was significantly higher than that two other systems. The decreasing rate of IFSS was the fastest in bioactive glass fiber/PLLA composite, whereas that of chitosan fiber/PLLA composite was the slowest. With increasing hydrolysis time, distribution of AE amplitude was narrow, and AE energy decreased gradually.

• Journal of the Korean Ceramic Society
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• v.45 no.10
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• pp.631-637
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• 2008

Self-standing mesoporous bioactive glass/poly($\varepsilon$-caprolactone) composite thin films with good molding capability, bioactivity, and biocompatibility in vitro, which may find potential applications in tissue engineering and drug storage, were prepared using a combination of the sol-gel, polymer templating, and water casting method. The thickness of self-standing films was affected by the difference of dielectric constant between distilled water and organic solvent.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.5
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• pp.402-407
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• 2006

Vascular endothelial cells release proteinases that degrade the extracellular matrix (ECM), thus enabling cell migration during angiogenesis and vasculogenesis. Sildenafil citrate stimulates the nitric oxide-cyclic guanosine monophosphate pathway through inhibition of phosphodiesterase type V (PDE5). In this report, we examined the mechanisms underlying sildenafil citrate-induced cell migration using cultured mouse aortic endothelial cells (MAECs). Sildenafil citrate induced migration and proteinase secretion by murine endothelial cells. Sildenafil citrate induced the secretion of matrix metalloproteinase-2 (MMP-2) and MMP-9, which is inhibited by $NF-{\kappa}B$ inhibitors. Sildenafil citrate also induced the secretion of plasmin, which is inhibited by PI 3'-kinase inhibitors. It is suggested that sildenafil citrate-induced migrating activity in endothelial cells may be accomplished by increased secretion of proteinases.

• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2585-2591
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• 2012

A series of heterocyclic chalcone derivatives bearing heterocycles such as thiophene or furan ring as an isostere of benzene ring were carefully prepared, and the influence of heterocycles on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities was systematically investigated. Structure-activity relationships (SAR) analysis showed that the activities of thiophene ring-containing chalcones were higher than those of furan ring-containing chalcones, and the presence of methyl substituent of heterocyclic ring distinctly affected the activities compared with non-substituted heterocycles in an opposite manner, with the 4'-methyl group of thiophene ring increasing activity and the 3'-methyl group of the furan ring decreasing activity. The distinct isosteric effect of heterocycles (i.e., thiophene or furan ring) on radical scavenging activities of heterocyclic chalones was distinctly demonstrated in our work.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.52.1-52.1
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• 2011

In this work, the effect of the addition of bioactive glass in the biocompatibility and mechanical behavior of conventional TTCP/DCPA based bone cement were investigated. The cement was initially modified with chitosan and HPMC which cross-linked with citric acid to improved mechanical properties.The injectable bone substitutes were further modified by adding varying amounts of bioactive glass (0%, 10%, 20% and 30%) and its effects on the biocompatibility of the material were studied. Afterbio-glass powders were mixed with the optimized composition for HPMC and citric acid content,the IBS was incubated at $37^{\circ}C$ at different time intervals and showed progressive formation of HAp with increasing time. Mechanical properties like Vickers hardness and compressive strength were found to increase with the increasing amount of bioactive glass addition and that setting time was shortened. The fabricated IBS morphologies were further characterized using SEM. MTT assay was performed to check the cell cytotoxicity and cell proliferation for 1, 3 and 5 days. Cell morphology, adhesion and proliferation behavior of cell in the IBS by culturing MG-63 cells on the IBS for 20, 60 and 90 mins and 1, 3 and 5 days was also investigated. All the results showed increasing biocompatibility as the bioglass content increased. MTT results found the materials to be cytocompatible and SEM images showed that cells attached and proliferated successfully.