The Experts below are selected from a list of 1962 Experts worldwide ranked by ideXlab platform
Yong-keun Lee - One of the best experts on this subject based on the ideXlab platform.
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Opalescence of human teeth and dental esthetic restorative materials
Dental Materials Journal, 2016Co-Authors: Yong-keun LeeAbstract:Human tooth enamel is opalescent, which renders teeth bluish in reflected and orange in transmitted color. The aim was to review opalescent property of teeth and application and mimetic reproduction in esthetic restorations. A PubMed search for articles published in English till 2015 on the Opalescence of teeth and esthetic materials revealed 29 relevant papers. Opalescence was measured with OP-RT index, which was calculated as the difference in the yellow-blue and red-green color coordinates between the reflected and transmitted colors. Mean OP-RT value of human enamel was 22.9. OP-RT values of direct resin composites changed after polymerization, and the range in these materials was 5.7-23.7. OP-RT value ranges were 1.6-6.1 and 2.0-7.1 for the core and veneer ceramics, respectively. Since the OP-RT values of esthetic materials were lower than that of enamel, it is recommended that materials that can reproduce the Opalescence of enamel be further designed.
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effects of aging and hema content on the translucency fluorescence and Opalescence properties of experimental hema added glass ionomers
Dental Materials Journal, 2010Co-Authors: Yong-keun Lee, Y U Bin, Guangfeng Zhao, Jin Ik LimAbstract:Changes in the translucency, fluorescence, and Opalescence of experimental 10–50% 2-hydroxyethyl methacrylate (HEMA)-added glass ionomers (HAGIs) after 5,000 cycles of thermocycling were determined and compared with those of commercial resin-modified glass ionomers (RMGIs). Changes in the translucency (TP), fluorescence (FL), and Opalescence (OP) parameters were in the range of –3.5 to 0.2, –2.3 to 0.3 and –2.6 to 9.1 units respectively for HAGIs; and –0.9 to 0.3, –0.7 to 0.6, and 1.1 to 2.3 units respectively for RMGIs. Changes in the TP, FL, and OP of HAGIs were influenced by the HEMA content and powder shade, and were generally larger than those of RMGIs. Since the changes in TP, FL, and OP of experimental HAGIs were influenced by the HEMA content, there arises a need to determine the optimal HEMA ratio to attain high stability for these optical properties. In addition, results of this study showed that apart from optimal HEMA ratio, future studies should include other aspects and factors that contribute to age-dependent changes in optical properties.
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difference in Opalescence of restorative materials by the illuminant
Dental Materials, 2009Co-Authors: Yong-keun LeeAbstract:Abstract Objectives To determine the differences in the Opalescence parameter ( OP ) of indirect and direct resin composites, veneer ceramics and bovine enamel relative to the CIE standard illuminants D65, A and F2. Methods BelleGlass NG (indirect resin; 10 shades) and Estelite Sigma (direct resin; 12 shades), and 4 shades of veneer ceramics were investigated. Bovine enamel was used as a reference. Reflected and transmitted colors of specimens were measured relative to the illuminants D65, A and F2 with a reflection spectrophotometer. OP values relative to the three illuminants [ OP (D65), OP (A) and OP (F2)], difference in OP ( ΔOP ) and OP difference ratio relative to OP (D65) [ ΔOP / OP (D65)] by the change of illuminants were calculated. Within each restorative material, ΔOP and ΔOP / OP (D65) values were analyzed with two-way analysis of variance (ANOVA), with the fixed factors of the shade designation and the combination of illuminants ( α = 0.05). Results ΔOP and ΔOP / OP (D65) values were influenced by the two factors within each restorative material based on two-way ANOVA. High opalescent materials showed higher ΔOP values. OP (D65) was lower than OP (F2) and OP (A) values. Restorative materials showed lower ΔOP / OP (D65) values than bovine enamel. Correlation coefficients between OP values relative to different illuminants were higher than 0.961 ( P Significance Direct resin composites instead of ceramics or indirect resin composites should be recommended in clinical dentistry since they showed similar Opalescence properties as compared with natural tooth enamel.
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Opalescence and fluorescence properties of indirect and direct resin materials.
Acta Odontologica Scandinavica, 2009Co-Authors: Sang-hoon Song, Jin-soo Ahn, Yong-keun LeeAbstract:Objective. To measure the Opalescence and fluorescence properties of indirect and direct resin materials before and after polymerization, and to determine the influence of the material and shade group combination on these properties. Material and methods. BelleGlass NG (BG, indirect resin) and Estelite Sigma (ES, direct resin), each composed in 3 shade groups (EN, OD and TL for BG; BS, AS and OP for ES) out of a total of 16 shades were investigated. Resin material was packed into a mold (the BEC condition) and polymerized with a light-polymerization unit (CWL). Secondary polymerization (CIC) was performed for BG. Color was measured in the BEC, CWL, and CIC conditions, and the Opalescence parameter (OP) and fluorescence parameter (FL) were calculated. Results. For the OP, the mean for BG material was 24.3 before polymerization, which changed to 19.9 after polymerization (CIC). In the case of ES, the mean OP before polymerization was 25.6, which changed to 12.4 after polymerization (CWL). For the FL, the me...
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Opalescence of all ceramic core and veneer materials
Dental Materials, 2009Co-Authors: Moonsang Cho, Yong-keun LeeAbstract:Abstract Objectives The enamel of natural teeth is opalescent, where there is light scattering of the shorter wavelengths of the visible spectrum, giving a tooth a bluish appearance in the reflected color and an orange/brown appearance in the transmitted color. The objective of this study was to determine the Opalescence of all-ceramic core, veneer and layered specimens with a color measuring spectrophotometer. Methods Colors of core (A2-corresponding shade), veneer (A2- and A3-corresponding shades) and layered (A2- and A3-layered) ceramics for all-ceramic restorations in clinically relevant thicknesses were measured in the reflectance and transmittance modes. The Opalescence parameter (OP), which was calculated as the difference in blue-yellow coordinate (Δb*) and red-green coordinate (Δa*), and the differences in blue-yellow coordinate (Δb*) and in color ( Δ E a b * ) between the reflected and transmitted colors were calculated. One-way ANOVA was performed for the OP values of the core, veneer and layered specimens by the kind of materials. Regression analysis was performed between the OP and Δb*, and the OP and Δ E a b * values. Results The range of the OP value was 1.6–6.1, 2.0–7.1, 1.3–5.0 and 1.6–4.2 for the core, veneer, A2- and A3-layered specimens, respectively, all of which were significantly influenced by the kind of materials (p Δ E a b * values showed significant correlations within each of the core and veneer ceramics. Significance Opalescence varied by kind of ceramics. The OP values of ceramics were lower than those of tooth enamel. All-ceramic materials that can simulate the Opalescence of natural teeth should be developed.
Devendra S Kalonia - One of the best experts on this subject based on the ideXlab platform.
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pharmaceutical perspective on Opalescence and liquid liquid phase separation in protein solutions
Molecular Pharmaceutics, 2016Co-Authors: Ashlesha S Raut, Devendra S KaloniaAbstract:Opalescence in protein solutions reduces aesthetic appeal of a formulation and can be an indicator of the presence of aggregates or precursor to phase separation in solution signifying reduced product stability. Liquid–liquid phase separation of a protein solution into a protein-rich and a protein-poor phase has been well-documented for globular proteins and recently observed for monoclonal antibody solutions, resulting in physical instability of the formulation. The present review discusses Opalescence and liquid–liquid phase separation (LLPS) for therapeutic protein formulations. A brief discussion on theoretical concepts based on thermodynamics, kinetics, and light scattering is presented. This review also discusses theoretical concepts behind intense light scattering in the vicinity of the critical point termed as “critical Opalescence”. Both Opalescence and LLPS are affected by the formulation factors including pH, ionic strength, protein concentration, temperature, and excipients. Literature reports...
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Opalescence in monoclonal antibody solutions and its correlation with intermolecular interactions in dilute and concentrated solutions
Journal of Pharmaceutical Sciences, 2015Co-Authors: Ashlesha S Raut, Devendra S KaloniaAbstract:Opalescence indicates physical instability of a formulation because of the presence of aggregates or liquid-liquid phase separation in solution and has been reported for monoclonal antibody (mAb) formulations. Increased solution Opalescence can be attributed to attractive protein-protein interactions (PPIs). Techniques including light scattering, AUC, or membrane osmometry are routinely employed to measure PPIs in dilute solutions, whereas Opalescence is seen at relatively higher concentrations, where both long- and short-range forces contribute to overall PPIs. The mAb molecule studied here shows a unique property of high Opalescence because of liquid-liquid phase separation. In this study, Opalescence measurements are correlated to PPIs measured in diluted and concentrated solutions using light scattering (kD ) and high-frequency rheology (G'), respectively. Charges on the molecules were calculated using zeta potential measurements. Results indicate that high Opalescence and phase separation are a result of the attractive interactions in solution; however, the presence of attractive interactions do not always imply phase separation. Temperature dependence of Opalescence suggests that thermodynamic contribution to Opalescence is significant and Tcloud can be utilized as a potential tool to assess attractive interactions in solution.
Ashlesha S Raut - One of the best experts on this subject based on the ideXlab platform.
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pharmaceutical perspective on Opalescence and liquid liquid phase separation in protein solutions
Molecular Pharmaceutics, 2016Co-Authors: Ashlesha S Raut, Devendra S KaloniaAbstract:Opalescence in protein solutions reduces aesthetic appeal of a formulation and can be an indicator of the presence of aggregates or precursor to phase separation in solution signifying reduced product stability. Liquid–liquid phase separation of a protein solution into a protein-rich and a protein-poor phase has been well-documented for globular proteins and recently observed for monoclonal antibody solutions, resulting in physical instability of the formulation. The present review discusses Opalescence and liquid–liquid phase separation (LLPS) for therapeutic protein formulations. A brief discussion on theoretical concepts based on thermodynamics, kinetics, and light scattering is presented. This review also discusses theoretical concepts behind intense light scattering in the vicinity of the critical point termed as “critical Opalescence”. Both Opalescence and LLPS are affected by the formulation factors including pH, ionic strength, protein concentration, temperature, and excipients. Literature reports...
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Opalescence in monoclonal antibody solutions and its correlation with intermolecular interactions in dilute and concentrated solutions
Journal of Pharmaceutical Sciences, 2015Co-Authors: Ashlesha S Raut, Devendra S KaloniaAbstract:Opalescence indicates physical instability of a formulation because of the presence of aggregates or liquid-liquid phase separation in solution and has been reported for monoclonal antibody (mAb) formulations. Increased solution Opalescence can be attributed to attractive protein-protein interactions (PPIs). Techniques including light scattering, AUC, or membrane osmometry are routinely employed to measure PPIs in dilute solutions, whereas Opalescence is seen at relatively higher concentrations, where both long- and short-range forces contribute to overall PPIs. The mAb molecule studied here shows a unique property of high Opalescence because of liquid-liquid phase separation. In this study, Opalescence measurements are correlated to PPIs measured in diluted and concentrated solutions using light scattering (kD ) and high-frequency rheology (G'), respectively. Charges on the molecules were calculated using zeta potential measurements. Results indicate that high Opalescence and phase separation are a result of the attractive interactions in solution; however, the presence of attractive interactions do not always imply phase separation. Temperature dependence of Opalescence suggests that thermodynamic contribution to Opalescence is significant and Tcloud can be utilized as a potential tool to assess attractive interactions in solution.
Kentaro Shiraki - One of the best experts on this subject based on the ideXlab platform.
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arginine and its derivatives suppress the Opalescence of an antibody solution
Journal of Pharmaceutical Sciences, 2021Co-Authors: Shogo Oki, Suguru Nishinami, Yoshitaka Nakauchi, Toshihiko Ogura, Kentaro ShirakiAbstract:Abstract Opalescence is a problem concerned with the stability of an antibody solution. It occurs when a high concentration of a protein is present. Arginine (Arg) is a versatile aggregation suppressor of proteins, which is among the candidates that suppress Opalescence in antibody solutions. Here, we investigated the effect of various types of small molecular additives on Opalescence to reveal the mechanism of Arg in preventing Opalescence in antibody solution. As expected, Arg suppressed the Opalescence of the immunoglobulin G (IgG) solution. Arg also concentration dependently inhibited the formation of microstructures in IgG molecules. Interestingly, the intrinsic fluorescence spectra of highly concentrated IgG solutions differed from those having low concentrations, even though IgG retained a distinct tertiary structure. Arginine ethylester was more effective in suppressing the Opalescence of IgG solutions than Arg, whereas lysine and γ-guanidinobutyric acid were less effective. These results indicated that positively charged groups of both α-amine and guanidinium actively influence Arg as an additive for suppressing Opalescence. Diols, which are the suppressors of the liquid–liquid phase separation of proteins were also effective in suppressing the Opalescence. These results therefore provide insight into the control of Opalescence of antibody solutions at high concentrations using solution additives.
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arginine suppresses Opalescence and liquid liquid phase separation in igg solutions
International Journal of Biological Macromolecules, 2018Co-Authors: Shogo Oki, Suguru Nishinami, Kentaro ShirakiAbstract:Abstract Antibody formulation often necessitates the protein concentration to be increased above 100 mg/ml, because of the large therapeutic doses of antibodies required and the volume limitations of subcutaneous injections. However, high concentrations of antibody lead to opalescent states in solution, resulting in safety and application problems. In this study, we investigated the effect of additives on Opalescence in IgG solutions. Arginine (Arg) was observed to most effectively suppress Opalescence in IgG solutions among the additives tested, which included guanidine hydrochloride, NaCl, and other amino acids. Moreover, Arg also suppressed liquid–liquid phase separation (LLPS) of highly concentrated IgG solutions during incubation at low temperature. Comparative analysis showed that the effects of Arg on Opalescence and LLPS in IgG solutions result from its unique structure, which comprises an amino acid main chain, a guanidinium group, and a counter ion. These results indicate that Arg has high potency as an excipient in antibody drug formulations for the suppression of Opalescence and LLPS as well as protein aggregation.
Jifeng Zhang - One of the best experts on this subject based on the ideXlab platform.
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Opalescence of an igg2 monoclonal antibody solution as it relates to liquid liquid phase separation
Journal of Pharmaceutical Sciences, 2011Co-Authors: Bruce D Mason, Le Zhang, Richard L Remmele, Jifeng ZhangAbstract:Opalescence for a monoclonal antibody solution was systematically studied with respect to temperature, protein concentration, ionic strength (using KCl), and pH conditions. Multiple techniques, including measurement of light scattering at 90° and transmission, Tyndall test, and microscopy, were deployed to examine the Opalescence behavior. Near the vicinity of the critical point on the liquid-liquid coexistence curve in the temperature-protein concentration phase diagram, the enhanced concentration fluctuations significantly contributed to the critical Opalescence evidently by formation of small liquid droplets. Furthermore, our data confirm that away from the critical point, the Opalescence behavior is related to the antibody self-association (agglomeration) caused by the attractive antibody-antibody interactions. As expected, at a pH near the pI of the antibody, the solution became less opalescent as the ionic strength increased. However, at a pH below the pI, the Opalescence of the solution became stronger, reached a maximum, and then began to drop as the ionic strength further increased. The change in the Opalescence correlated well with the trends of protein-protein interactions revealed by the critical temperature from the liquid-liquid phase separation.
