• Journal of the Korean Applied Science and Technology
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• v.19 no.3
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• pp.189-197
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• 2002

The color stability and purity from OLED is of current interest. Aggregation of dyes alters the device color after fabrication of the devices. Exciplex and electroplex formations have been proposed to explain the aggregate color change. We investigate the possibility of exciplex formation and propose the new electroplex state that can cause the bathochromic shift of the electroluminescence spectrum from the devices with TPD/PBD layers. The photoluminescence maximum of the device was 420nm, and the electroluminescence maximum of the device to became 480nm. The bathochromic shift cannot be attained with photoluminescence study with highly concentrated TPD/PBD mixture. This clearly indicates that the 480nm spectrum of the devices is not resulted from the exciplex formation with TPD and PBD. We observed the overshoot in EL spectrum from the OLEDs. The most intense overshoot was observed at 460nm, which may be due to the aggregates that are formed after the electric field has been removed from the devices.

• Journal of Chest Surgery
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• v.36 no.9
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• pp.666-673
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• 2003

Cigarette smoking is the leading cause of the lung cancer. However, mechanism of action underlying the carcinogenesis in the lung still remains to be elucidated. The present study attempted to look into the carcinogenic potential of tobacco-specific nitrosamine, NNK (4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone) and the effects of protein kinase C (PKC) isoforms in an immortalized human epithelial cell model. Material and Method: Immortalized human epithelial cells were exposed with NNK and examined for its carcinogenic potential as measured by saturation density, soft-agar colony formation, and cell aggregation assay. The specific isoform of PKCs involved in the cellular transformation was analysed through western blot with monoclonal antibody and measured separately in cytosolic fraction and membrane fraction. Result: Human epithelial cells exposed with NNK showed prominent carcinogenic potential in saturation density, soft agar colony formation, and cell aggregation assay. PKC isoform analysis results are as follows: PKC- $\alpha$ showed significant translocation of protein levels from cytosolic fraction to membrane fraction, as analyzed by immunoblot. PKC- $\varepsilon$ showed a dose-dependent increase of translocation. PKC- λ was not affected by NNK treatment. Conclusion: The study demonstrated that there was a certain specificity in the patterns of isoform induction following chemical carcinogen exposure. Thus, it is suggested that identification of specific isoform be a clue to find target molecules in the carcinogenesis.

• Bulletin of the Korean Chemical Society
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• v.35 no.5
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• pp.1440-1448
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• 2014

Co(II)-tetrasulfonated phthalocyanine (CoTSP) is known to be aggregated to dimer at high concentration levels in water. A study on the aggregation of CoTSP using multivariate curve resolution analysis of the visible absorbance spectra over a concentration range of 30, 40 and 50 ${\mu}M$ in the presence of dimethyl sulfoxide (DMSO), dimethyl formamide (DMF), acetonitrile (AN) and ethanol (EtOH) in the concentration range of 0 to 3.57 M is conducted. A hard modeling-based multivariate curve resolution method was applied to determine the dissociation constants of the CoTSP aggregates at various temperatures ranging from 25, 45 and $65^{\circ}C$ and in the presence of various co-solvents. Dissociation constant for aggregation was increased and then decrease by temperature and concentration of phthalocyanine, respectively. Utilizing the vant Hoff relation, the enthalpy and entropy of the dissociation equilibriums were calculated. For the dissociation of both aggregates, the enthalpy and entropy changes were positive and negative, respectively. Molecular dynamics simulation of cosolvent effect on CoTSP aggregation was done to confirm spectroscopy results. Results of radial distribution function (RDF), root mean square deviation (RMSD) and distance curves confirmed more effect of polar solvent to decrease monomer formation.

• Biomolecules & Therapeutics
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• v.25 no.3
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• pp.223-230
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• 2017

Platelets play an essential role in hemostasis through aggregation and adhesion to vascular injury sites but their unnecessary activation can often lead to thrombotic diseases. Upon exposure to physical or biochemical stimuli, remarkable platelet shape changes precede aggregation or adhesion. Platelets shape changes facilitate the formation and adhesion of platelet aggregates, but are readily reversible in contrast to the irrevocable characteristics of aggregation and adhesion. In this dynamic phenomenon, complex molecular signaling pathways and a host of diverse cytoskeleton proteins are involved. Platelet shape change is easily primed by diverse pro-thrombotic xenobiotics and stimuli, and its inhibition can modulate thrombosis, which can ultimately contribute to the development or prevention of thrombotic diseases. In this review, we discussed the current knowledge on the mechanisms of platelet shape change and also pathological implications and therapeutic opportunities for regulating the related cytoskeleton dynamics.

• Bulletin of the Korean Chemical Society
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• v.7 no.4
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• pp.267-271
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• 1986

The ionomeric blend and the ionic aggregation studies by using a Fourier-transform infrared spectroscopy(FT-IR) are presented. Two ionomers were prepared, one is barium polyacrylate and the other is barium polystyrenesulfonate. The blend of the two ionomers of the barium salts shows intermolecular ionic interaction between the carboxylated ionomer and the sulfonated ionomer. This interaction leads to considerable differences between the spectrum of the blend and the sum of the spectra of the pure ionomers. From our results, it is shown that ionic interactions must play an important role in the compatibility of the two ionomers. In the ionic aggregation study, the bands due to asymmetric stretching mode of carboxylate anion(COO-) in the carboxylated ionomer and the ionomer blend increase in intensity with increasing the divalent barium cations. These results indicate the formation of ion pairs. The doublet due to the asymmetric stretching modes of the carboxylate anion(COO-) is concerned with a sort of local structure found in the ion aggregation. By considering a possible structure for multiplets in the blend, the spectral splitting and the frequency shift are well explained.

• Biomedical Science Letters
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• v.29 no.4
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• pp.242-248
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• 2023

Platelets are activated at the sites of vascular injury by a number of molecules, including adenosine diphosphate, collagen and thrombin. The full platelet aggregation is absolutely essential for the normal hemostasis. Glycyrrhiza glabra is a well-known medicinal herb that grows in various parts of the world and is known to have various effects such as antioxidant, anti-inflammatory, anti-atherogenic, anti-osteoporotic and skin-whitening. However, the platelet inhibitory effect of Glycyrrhiza glabra extract (GGE) has not been identified. In this study, we investigated if GGE inhibited platelet aggregation. We observed that GGE inhibited collagen-induced platelet aggregation, Ca²⁺ mobilization, and thromboxane A2 generation. In addition, GGE suppressed phosphorylation of phosphatidylinositol-3 kinase (PI3K), Akt and elevated phosphorylation of inositol 1,4,5-trisphosphate receptor (IP3R), vasodilator stimulated phosphoprotein (VASP). Taken together, GGE showed strong antiplatelet effects and may be used to block platelet-mediated cardiovascular diseases.

• The KIPS Transactions:PartC
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• v.11C no.5
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• pp.645-652
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• 2004

In this paper, we aggregate multi-links information between boundary nodes using the line segment scheme that aggregates topology in-formation within PG referring bandwidth and delay parameter. The proposed scheme can search multi-links efficiently using the depth priority method based on hop count instead of searching all links. To do this, we propose a modified line segment algorithm using two line segment method that represents two points which consist of delay-bandwidth pair to reduce topology information and provide a flexibility to the multi pie-links aggregation. And we apply it to current star topology aggregation. To evaluate performance of the proposed scheme, we compare/analyze the current method with the proposed scheme with respect to call success rate, access time and crankback rate. Through the simulation result analysis, the proposed star topology aggregation scheme presents the better performance than existing scheme.

• Journal of Nutrition and Health
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• v.32 no.4
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• pp.384-393
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• 1999

The degree of platelet aggregation, thromboxane B2(TXB2)formation and fatty acid composition of platelet phospholipids(PL) were investigated in 24 healthy male subjects who for five weeks consumed either corn oil(CO) rich in linoleic acid(LA), perilla oil (PO) rich in $\alpha$-linoleic acid($\alpha$-LAN), or canola oil(CNO) rich in oleic acid(OA) as a major fat source. Total fat intake was 30% of total calories and prescribed oil intake of each dietary group was 50% of the total fat intake. In the CO group, significantly decreased contents of polyunsaturated fatty acids(PUFA), n-6 PUFA, n-3 PUFA and eicosapentanoic acid(EPA) were observed, and significantly increased contents of OA and saturated fatty acids(SFA) were observed in platelet PL after 3 weeks and 5 weeks of dietary treatment. In the PO group, contents of OA and docosahexanoic acid(DHA) were increased, and the ratio of n-6/n-3 was decreased significantly in platelet PL after dietary treatment. The CNO group showed significatnlty decreased contents of PUFA, P/S ratio, n-6 PUFA, LA,(EPA+DHA)/arachidonic acid(AA), and significantly increased SFA contents after 3 weeks of the oil-based diet. The dietary-induced effects on fatty acid composition of platelet PL were observed mostly after 3 weeks of the oil-based diet. The dietary-induced effects on fatty acid composition of platelet PL were observed mostly after 3 weeks. Plasma TXB2 levels were increased after 3 and 5 weeks of dietary treatment. However, only the CO and CNO groups showed significantly increased plasma TXB2 levles after 3 and 5 weeks of dietary treatment. However, only the CO and CNO groups showed significantly increased plasma TXB2 levels after 5 weeks of experimental diets, when compared with initial values. Degree of platelet aggregation increased only in the CO group after dietary treatment. As a result, at week 5 the degree of platelet aggregation of the CO group was significantly higher than those of the PO and CNO groups. Among the three oil-based diets, the PO-based diet seems to have beneficial effects on atherosclerosis by influencing plasma TXB2 levels and the degree of platelet aggregation, while the CO-based diet showed the most adverse effects. Our results imply that plasma TXB2 levels might be affected by dietary fatty acid composition.

• Development and Reproduction
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• v.20 no.2
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• pp.101-108
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• 2016

Previously we observed that human adipose-derived stem cells (hADSCs) could form aggregation during culture in the presence of human serum (HS). In the present study, we have examined if the aggregation might result from the cell migration and analyzed the difference of cell adhesivity after culture in various conditions. When cells were cultured in fetal bovine serum (FBS) alone, there was no morphological change. Similarly, cells pretreated with FBS for 1 day or cultured in a mixture of FBS and HS showed little change. In contrast, cells cultured in HS alone exhibited formation of cell-free area (spacing) and/or cell aggregation. When cells cultured in FBS or pretreated with FBS were treated with 0.06% trypsin, almost cells remained attached to the dish surfaces. In contrast, when cells cultured in HS alone were examined, most cells detached from the dish by the same treatment. Treatment of cells with forskolin, isobutylmethyl xanthine (IBMX) or LY294002 inhibited the formation of spacing whereas H89 or Y27632 showed little effect. When these cells were treated with 0.06% trypsin after culture, most cells detached from the dishes as cells cultured in HS alone did. However, cells treated with IBMX exhibited weaker adhesivity than HS alone. Based on these observations, it is suggested that HS treatment might decrease the adhesivity and induce three-dimensional migration of hADSCs, in the latter of which cAMP signaling could be involved.

• Archives of Pharmacal Research
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• v.21 no.6
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• pp.774-778
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• 1998

Brazilin [7,11b-dihydrobenz[b]indeno[1,2-d]pyran-3,6a,9,10(6H)-tetrol] inhibited thrombin-, collagen- and ADP-induced aggregation of washed rat platelets. T hrombin- and collagen-induced ATP release were also inhibited by brazilin in a concentration-dependent manner. Brazilin inhibited the formation of platelet thromboxane $A_2$ caused by thrombin, whereas it had no effect on the prostaglandin $D_2$ formation. Brazilin inhibited $^3H$-arachidonic acid liberation from membrane phospholipids of thrombin-stimulated platelets. Brazilin inhibited the rise of intracellular free calcium caused by thrombin. These results indicate that the inhibition of phospholipase ($PLA_2$) activity and [$[Ca^{2+}]_1$ elevation might be at least a part of antiplatelet mechanism of brazilin.