• The Journal of Korean Medicine
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• v.29 no.4
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• pp.104-113
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• 2008

Objectives: The aim of this study was to investigate the influence of five herbal medicines on cytochrome P450 (CYP) 3A4 drug-metabolizing enzymes in human liver microsomes. Methods: By using of human liver microsomes, we extracted Cnidium officinale Makino, Rhus verniciflua Stokes, Prunus persica Batsch, Corydalis remota Fisch, Carthamus tinctorius Linne, which are called Hwalhyulgeoouhyak(活血祛瘀藥). Then they were incubated and measured for relative enzyme activity under incubation conditions compared to ketoconazole, which is known as a representative inhibitor of CYP 3A4. Results: We showed that all of five traditional herbal medicines had no inhibition effect of CYP 3A4 at 10, 20, 30, 40, and 50${\mu}g/m{\ell}$ doses in human liver microsomes, although Rhus verniciflua Stokes (RVS) showed a little inhibition as about 95% enzyme activity of control. However, this result was not enough to prove that RVS has a CYP 3A4 inhibition effect. Moreover, we can't confirm that those rates have significant induction effect on CYP 3A4. Conclusions: The result of this study could support that those herbal medicines are more reliable than chemical drugs, even if this is a basic step to prove that result.

• The Journal of Advanced Prosthodontics
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• v.3 no.4
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• pp.221-228
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• 2011

PURPOSE. Veneering porcelain might be delaminated from underlying zirconia-based ceramics. The aim of this study was the evaluation of the effect of different surface treatments and type of zirconia (white or colored) on shear bond strength (SBS) of zirconia core and its veneering porcelain. MATERIALS AND METHODS. Eighty zirconia disks (40 white and 40 colored; 10 mm in diameter and 4 mm thick) were treated with three different mechanical surface conditioning methods (Sandblasting with $110{\mu}m$ $Al_2O_3$ particle, grinding, sandblasting and liner application). One group had received no treatment. These disks were veneered with 3 mm thick and 5 mm diameter Cercon Ceram Kiss porcelain and SBS test was conducted (cross-head speed = 1 mm/min). Two and one way ANOVA, Tukey's HSD Past hoc, and T- test were selected to analyzed the data (${\alpha}=0.05$). RESULTS. In this study, the factor of different types of zirconia ceramics (P=.462) had no significant effect on SBS, but the factors of different surface modification techniques (P=.005) and interaction effect (P=.018) had a significant effect on SBS. Within colored zirconia group, there were no significant differences in mean SBS among the four surface treatment subgroups (P=0.183). Within white zirconia group, "Ground group" exhibited a significantly lower SBS value than "as milled" or control (P=0.001) and liner (P=.05) groups. CONCLUSION. Type of zirconia did not have any effect on bond strength between zirconia core and veneer ceramic. Surface treatment had different effects on the SBS of the different zirconia types and grinding dramatically decreased the SBS of white zirconia- porcelain.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.36 no.1
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• pp.1-6
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• 2010

Purpose: Chemokines are structurally related, small polypeptide signaling molecules that bind to and activate a family of transmembrane G protein-coupled receptors, the chemokine receptors. Recently, interaction between the chemokine receptor CXCR4 and its ligand, stromal cell-derived factor 1 (SDF-1 or CXCL12), has been found to play an important role in tumorigenicity, proliferation, metastasis and angiogenesis in many cancers such as lung cancer, breast cancer, melanoma, glioblastoma, pancreatic cancer and cholangiocarcinoma. Hence, the goal of this study is to identify the correlation of clinicopathological factors and the up-regulation of SDF-1 expression in oral squamous cell carcinoma. Material and methods: We studied the immunohistochemical staining of SDF-1, quantitative RT-PCR (qRT-PCR) of SDF-1 gene in 20 specimens of 20 patients with oral squamous cell carcinoma. Results: 1. In the immunohistochemical study of poor differentiated and invasive oral squamous cell carcinoma, the high level staining of SDF-1 was observed. And the correlation between immunohistochemical SDF-1 expression and tumor nodes metastases (TNM) classification of specimens was significant.($x^2$ test, P < 0.05) 2. In the SDF-1 gene qRT-PCR analysis, SDF-1 expression was more in tumor tissue than in carcinoma in situ tissue. Paired-samples analysis determined the difference of SDF-1 mRNA expression level between the cancer tissue and the carcinoma in situ tissue.(Student's t-test, P < 0.05) Conclusion: These findings suggest that up-regulation of the SDF-1 may play a role in progression and invasion of oral squamous cell carcinoma.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1995.04a
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• pp.81-81
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• 1995

It is well known that Src Homology 2(SH2) domain in many intracellular signal transduction proteins is very important. The domain has about 100 amino acid residues and bind phosphotyrosine-containing peptide with high affinity and specificity. Lck SH2 domain is a Src-like, lymphocyte-specific tyrosine kinase. An 11-residue phosphopeptide derived from the hamster polvoma middle-T antigen, EPQp YEEIPIYL, binds with an 1 nM dissociation constant to Lck SH2 domain. And it is known that the phosphotyrosine and isoleucine residues of the peptide are tightly bound by two well-defined pockets on Lck SH2 domain's surface. To investigate the conformational changes during complexation of SH2 domain with phosphopeptide we have performed the molecular dynamics simulation for Lck SH2 domain with peptide and peptide-free form at look in aqueous solution. More than 3000 water molecules were incorporated to solvate Lck SH2 domain and peptide. Periodic boundary condition has been applied in molecular dynamics simulation. Data analysis with the results of that simulation shows that the phosphopeptide makes primary interaction with the Lck SH2 domain at six central residues, The comparison of the complexed and uncomplexed SH2 domain structures in solution has revealed only relatively small change. But the hydrophilic and hydrophobic pockets in the protein surface show the conformational changes in spite of the small structural difference between the complex and peptide-free forms.

• Archives of Pharmacal Research
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• v.28 no.10
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• pp.1196-1202
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• 2005

Omeprazole (OMP) is a proton pump inhibitor used as an oral treatment for acid-related gastrointestinal disorders. In the liver, it is primarily metabolized by cytochrome P-450 (CYP450) isoenzymes such as CYP2C19 and CYP3A4. 5-Hyroxyomeprazole (5-OHOMP) and omeprazole sulfone (OMP-SFN) are the two major metabolites of OMP in human. Cimetidine (CMT) inhibits the breakdown of drugs metabolized by CYP450 and reduces, the clearance of coad-ministered drug resulted from both the CMT binding to CYP450 and the decreased hepatic blood flow due to CMT. Phenobarbital (PB) induces drug metabolism in laboratory animals and human. PB induction mainly involves mammalian CYP forms in gene families 2B and 3A. PB has been widely used as a prototype inducer for biochemical investigations of drug metabolism and the enzymes catalyzing this metabolism, as well as for genetic, pharmacological, and toxicological investigations. In order to investigate the influence of CMT and PB on the metabolite kinetics of OMP, we intravenously administered OMP (30 mg/kg) to rats intraperitoneally pretreated with normal saline (5 mL/kg), CMT (100 mg/kg) or PB (75 mg/kg) once a day for four days, and compared the pharmacokinetic parameters of OMP. The systemic clearance ($CL_{t}$) of OMP was significantly (p<0.05) decreased in CMT-pretreated rats and significantly (p<0.05) increased in PB-pretreated rats. These results indicate that CMT inhibits the OMP metabolism due to both decreased hepatic blood flow and inhibited enzyme activity of CYP2C19 and 3A4 and that PB increases the OMP metabolism due to stimulation of the liver blood flow and/or bile flow, due not to induction of the enzyme activity of CYP3A4.

• Journal of Nuclear Fuel Cycle and Waste Technology
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• v.1 no.1
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• pp.65-73
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• 2013

Temperature-dependent hydrolysis behaviors of aqueous U(VI) species were investigated with time-resolved laser fluorescence spectroscopy (TRLFS) in the temperature range from 15 to $75^{\circ}C$. The formation of four different U(VI) hydrolysis species was measured at pHs from 1 to 7. The predominant presence of $UO{_2}^{2+}$, $(UO_2)_2(OH){_2}^{2+}$, $(UO_2)_3(OH){_5}^+$, and $(UO_2)_3(OH){_7}^-$ species were identified based on the spectroscopic properties such as fluorescence wavelengths and fluorescence lifetimes. With an increasing temperature, a remarkable decrement in the fluorescence lifetime for all U(VI) hydrolysis species was observed, representing the dynamic quenching behavior. Furthermore, the increase in the fluorescence intensity of the further hydrolyzed U(VI) species was clearly observed at an elevated temperature, showing stronger hydrolysis reactions with increasing temperatures. The formation constants of the U(VI) hydrolysis species were calculated to be $log\;K{^0}_{2,2}=-4.0{\pm}0.6$ for $(UO_2)_2(OH){_2}^{2+}$, $log\;K{^0}_{3,5}=-15.0{\pm}0.3$ for $(UO_2)_3(OH){_5}^+$, and $log\;K{^0}_{3,7}=-27.7{\pm}0.7$ for $(UO_2)_3(OH){_7}^-$ at $25^{\circ}C$ and I = 0 M. The specific ion interaction theory (SIT) was applied for the extrapolation of the formation constants to infinitely diluted solution. The results of temperature-dependent hydrolysis behavior in terms of the U(VI) fluorescence were compared and validated with those obtained using computational methods (DQUANT and constant enthalpy equation). Both results matched well with each other. The reaction enthalpies and entropies that are vital for the computational methods were determined by a combination of the van't Hoff equation and the Gibbs free energy equation. The temperature-dependent hydrolysis reaction of the U(VI) species indicates the transition of a major U(VI) species by means of geothermal gradient and decay heat from the radioactive isotopes, representing the necessity of deeper consideration in the safety assessment of geologic repository.

• Advances in materials Research
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• v.8 no.1
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• pp.47-73
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• 2019

Joining of Mg/Ti hybrid structures by welding for automotive and aerospace applications has attracted great attention in recent years due mainly to its potential benefit of energy saving and emission reduction. However, joining them has been hampered with many difficulties due to their physical and metallurgical incompatibilities. Different joining processes have been employed to join Mg/Ti, and in most cases in order to get a metallurgical bonding between them was the use of an intermediate element at the interface or mutual diffusion of alloying elements from the base materials. The formation of a reaction product (in the form of solid solution or intermetallic compound) along the interface between the Mg and Ti is responsible for formation of a metallurgical bond. However, the interfacial bonding achieved and the joints performance depend significantly on the newly formed reaction product(s). Thus, a thorough understanding of the interaction between the selected intermediate elements with the base metals along with the influence of the associated welding parameters are essential. This review is timely as it presents on the current paradigm and progress in welding and joining of Mg/Ti alloys. The factors governing the welding of several important techniques are deliberated along with their joining mechanisms. Some opportunities to improve the welding of Mg/Ti for different welding techniques are also identified.

• Journal of Powder Materials
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• v.29 no.2
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• pp.99-109
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• 2022

Powder flowability is critical in additive manufacturing processes, especially for laser powder bed fusion. Many powder features, such as powder size distribution, particle shape, surface roughness, and chemical composition, simultaneously affect the flow properties of a powder; however, the individual effect of each factor on powder flowability has not been comprehensively evaluated. In this study, the impact of particle shape (sphericity) on the rheological properties of Ti-6Al-4V powder is quantified using an FT4 powder rheometer. Dynamic image analysis is conducted on plasma-atomized (PA) and gas-atomized (GA) powders to evaluate their particle sphericity. PA and GA powders exhibit negligible differences in compressibility and permeability tests, but GA powder shows more cohesive behavior, especially in a dynamic state, because lower particle sphericity facilitates interaction between particles during the powder flow. These results provide guidelines for the manufacturing of advanced metal powders with excellent powder flowability for laser powder bed fusion.

• Journal of Korean Dental Science
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• v.16 no.2
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• pp.192-203
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• 2023

Purpose: This study is to investigate the distribution of natural tooth shades in the Korean elderly population to quantify the correlation and changes of tooth color with age and gender. In addition, the possible effects of habits on tooth color were assessed. Materials and Methods: The tooth color of one of the maxillary central incisors of 200 Korean individuals aged 50 to 89 years, males and female, was measured using the portable intraoral spectrophotometer (VITA Easyshade V). CIELab and CIELCh color coordinates were recorded. We conducted the survey about the tobacco smoking, chronic disease, medication, eating habits, oral health behaviors and satisfaction with tooth color. Experimental data were statistically analyzed by using the t-test (P<0.05), two-way analysis of variance and Pearson's correlation test. Result: The most frequent color in the Korean elderly population was 3M3 & A3.5 shade. L^* and h^* values decreased, whereas C^*, a^* and b^* values increased progressively with age. There was a significant interaction between age and color coordinates for b^* values (r=0.245, P<0.05). Males generally have significantly higher C^*, a^*, b^* values and lower L^*, h^* value compared to females. Individuals who consumed alcohol had a higher L^* value (P<0.05). Conclusion: Within the limitation of this study, the central incisors were getting darker, more reddish, and yellowish with age. Information on the chromatic range of natural teeth by age and gender could help to select colors for esthetic dental restorations.

• Research in Plant Disease
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• v.10 no.4
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• pp.217-226
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• 2004

One hundred isolates of Magnaporthe grisea from Korea and China were characterized for pathogenicity using eight Korean differential varieties(KDV), six Chinese differential varieties(CDV) and six near isogenic lines(NILs) developed in China. The restriction length polymorphism of M. grisea isolates from each country also was analyzed using MGR586 as a probe. One hundred Korean isolates classified into 17 races on KDV were grouped into 29 pathotypes on Chinese near isogenic lines(NILs). Virulence of 46% of Korean isolates against all the six Chinese NILs indicated that the current six Chinese NILs alone was not enough to be used as differential varieties in Korea. Especially, susceptibility of the BL1 carrying resistance gene Pi-b to 70% of tested Korean isolates suggested that BL1(Pi-b) may not be a useful resistance source to Korean blast. Based on the virulence assays of M. grisea populations from each country were divided into two groups. About 50% of Chinese isolates showed similarity to the 30% of the Korean isolates. Especially, the isolates from northern part of China, where Japonica rice cultivars were grown, showed high similarity to the Korean isolates, while isolates from southern part of China, where Indica rice were mainly grown, showed low similarity to Korean isolates. The genome RFLPs of Korean isolates were quite different from those of southern part of China using MGR586 as a probe. These data indicated that the physiological and genetical characteristics of M. grisea population might be determined by strong interaction with cultivated rice.