• The Korean Journal of Financial Management
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• v.25 no.2
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• pp.165-190
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• 2008

The degree of informational asymmetry relating to the expiration of index derivatives is usually increased as an expiration day of index derivatives approaches. The increase in the degree of informational asymmetry may have some effects on trading behavior of investors. To examine what the effects look like, 'life cycle of index derivatives' in this study is defined as three adjacent periods around expiration day: pre-expiration period(a week before the expiration day), post-expiration period(a week after the expiration day), and remaining period. It is inspected whether stock investor's trading behavior is changed according to the life cycle of KOSPI200 derivatives and what the reason of the changing behavior is. We have four results. First, trading behavior of each investor group is categorized into three patterns: ㄱ-pattern, L-pattern and U-pattern. The level of trading activity is low for pre-expiration period and normal for other periods in the ㄱ-pattern. L-pattern means that the level of trading activity is high for post-expiration period and normal for other periods. In the U-pattern, the trading activity is reduced for remaining period compared to other periods. Second, individual investors have ㄱ-pattern of trading large stocks according to the life cycle of KOSPI200 index futures while they show U-pattern according to the life cycle of KOSPI200 index options. Their trading behavior is consistent with the prediction of Foster and Viswanathan(1990)'s model for strategic liquidity investors. Third, trading pattern of foreign investors in relation to life cycle of index derivatives is partially explained by the model, but trading pattern of institutional investors has nothing to do with the predictions of the model.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.187.2-187.2
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• 2003

The cyclin-dependent kinases (CDKs), a group of serine/threonine kinases that form active heterodimeric complexes binding to cyclins, are key regulators of the cell cycle. The role of cyclin dependent kinases(CDKs) in cell cycle regulation has stimulated an interest in them as potential targets for proliferative diseases such as cancer, psoriasis, and chemotherapeutic agent-induced alopecia. Indirubin, an active ingredient of a traditional Chinese recipe Danggui Longhui Wan, are potent CDK inhibitors competing with ATP for binding to the catalytic site of the CDKs. (omitted)

• The Korean Journal of Mycology
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• v.13 no.2
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• pp.65-74
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• 1985

Aspergillus niger IMI 41873 was cultured by the method of synchronous and submerged culture. Its sporulation occurred in the culture. Ribonucleic acids were extracted at each stage of life cycle. These RNAs were digested, separated and determined by P.E.I. cellulose TLC and HPLC methods. The levels of ribonucleic acids in sporulating mycelia were higher than those of conidiophore and phialide forming mycelia. Inosine 5-monophosphate and adenosine 5-monophosphate derivatives were found in HPLC separations. The levels of inosine 5-monophosphate and adenosine 5-monophosphate derivatives per ribonucleic acid were constant through differentiation. After the standard purine necleosides and boiling water extracts from A. bisporus, F. velutipes and L. edodes were added into the culture, their effects on sporulation were examined. Sporulation was greatly enhanced in each adding experiment.

• BMB Reports
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• v.53 no.3
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• pp.166-171
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• 2020

A chemical library comprising 2,354 drug-like compounds was screened using a transcription and replication-competent viruslike particle (trVLP) system implementing the whole Ebola virus (EBOV) life cycle. Dose-dependent inhibition of Ebola trVLP replication was induced by 15 hit compounds, which primarily target different types of G protein-coupled receptors (GPCRs). Based on the chemical structure, the compounds were divided into three groups, diphenylmethane derivatives, promazine derivatives and chemicals with no conserved skeletons. The third group included sertindole, raloxifene, and ibutamoren showing prominent antiviral effects in cells. They downregulated the expression of viral proteins, including the VP40 matrix protein and the envelope glycoprotein. They also reduced the amount of EBOV-derived tetracistronic minigenome RNA incorporated into progeny trVLPs in the culture supernatant. Particularly, ibutamoren, which is a known agonist of growth hormone secretagogue receptor (GHSR), showed the most promising antiviral activity with a 50% effective concentration of 0.2 μM, a 50% cytotoxic concentration of 42.4 μM, and a selectivity index of 222.8. Here, we suggest a strategy for development of anti-EBOV therapeutics by adopting GHSR agonists as hit compounds.

• Journal of Integrative Natural Science
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• v.9 no.4
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• pp.268-274
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• 2016

Filariasis causing nematode Brugia malayi is shown to harbor wolbachia bacteria as symbionts. The sequenced genome of the wolbachia endosymbiont from B.malayi (wBm) offers an unprecedented opportunity to identify new wolbachia drug targets. Hence the enzyme carbonic anhydrase from wolbachia endosymbiont of Brugia malayi (wBm) which is responsible for the reversible interconversion of carbon dioxide and water to bicarbonate and protons (or vice versa) is chosen as the drug target for filariasis. This enzyme is thought to play critical functions in bacteria by involving in various steps of their life cycle which are important for survival, The 3D structure of wBm carbonic anhydrase is predicted by selecting a suitable template using the similarity search tool, BLAST. The BLAST results shows a hexapeptide transferase family protein from Anaplasma phagocytophilum (PDB ID: 3IXC) having 77% similarity and 54% identity with wBm carbonic anhydrase. Hence the above enzyme is chosen as the template and the 3D structure of carbonic anhydrase is predicted by the tool Modeller9v7. Since the three dimensional structure of carbonic anhydrase from wolbachia endosymbiont of Brugia malayi has not yet solved, attempts were made to predict this protein. The predicted structure is validated and also molecular docking studies are carried out with the suitable inhibitors that have been solved experimentally.

• Oncology Letters
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• v.17 no.5
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• pp.4735-4741
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• 2019

Fms-like tyrosine kinase 3 (FLT3) is a valuable pharmacological target in the treatment of acute myeloid leukemia (AML). LDD-1075 and LDD-1076 are indirubin derivatives, and LDD-1075 is the ester form of LDD-1076. LDD-1076 exhibited a potent in vitro FLT3 kinase activity inhibition with an IC₅₀ of 7.89 nM, whereas, LDD-1075 demonstrated a relatively weak activity against FLT3 (IC₅₀ of 3.19 µM). In contrast with the results of the FLT3 kinase activity inhibition assay, the LDD-1076 did not affect the growth of the MV4-11 cell line, which harbors the constitutively activated form of the FLT3 mutation. Notably, LDD-1075 exhibited a strong cytotoxic effect against the MV4-11 cells. When LDD-1075 was incubated with the MV4-11 cell lysate, the formation of LDD-1076 was observed. Treatment with LDD-1075 inhibited the FLT3 phosphorylation along with the phosphorylation of the signal transducer and activator of transcription 5 protein, which is a downstream signal transducer of FLT3. Treatment with LDD-1075 induced apoptosis and cell cycle arrest at the G1 phase. The present study demonstrated that the LDD-1076 formed by the bioconversion of LDD-1075 is a potent FLT3 inhibitor with anti-leukemic activity.

• Journal of Microbiology
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• v.45 no.5
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• pp.431-440
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• 2007

A silkworm (Bombyx mori L.) extract known to contain naturally occurring iminosugars, including 1-deoxynojirimycin (1-DNJ) derived from the mulberry tree (Morus alba L.), was evaluated in surrogate HCV and HBV in vitro assays. Antiviral activity of the silkworm extract and one of its purified constituents, 1-DNJ, was demonstrated against bovine viral diarrhea virus (BVDV) and GB virus-B (GBV-B), both members of the Flaviviridae family, and against woodchuck hepatitis virus (WHV) and hepatitis B virus (HBV), both members of the Hepadnaviridae family of viruses. The silkworm extract exhibited a 1,300 fold greater antiviral effect against BVDV in comparison to purified 1-DNJ. Glycoprotein processing of BVDV envelope proteins was disrupted upon treatment with the naturally derived components. The glycosylation of the WHV envelope proteins was affected largely by treatment with the silkworm extract than with purified 1-DNJ as well. The mechanism of action for this therapy may lie in the generation of defective particles that are unable to initiate the next cycle of infection as demonstrated by inhibition of GBV-B in vitro. We postulate that the five constituent iminosugars present in the silkworm extract contribute, in a synergistic manner, toward the antiviral effects observed for the inhibition of intact maturation of hepatitis viral particles and may complement conventional therapies. These results indicate that pre-clinical testing of the natural silkworm extract with regards to the efficacy of treatment against viral hepatitis infections can be evaluated in the respective animal models, in preparation for clinical trials in humans.

• BMB Reports
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• v.51 no.8
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• pp.388-393
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• 2018

The activating transcription factor (ATF) 4 belongs to the ATF/CREB (cAMP Response Element Binding bZIP [Basic Leucine Zipper]) transcription factor family, and plays a central role in the UPR (Unfolded Protein Response) process in cells. The induction of ATF4 expression has previously been shown to increase the replication of HIV-1. However, the detailed mechanism underlying this effect and the factors involved in the regulation of ATF4 function are still unknown. Here, we demonstrate first that knocking out ATF4 using siRNA shows a strong negative effect on HIV-1 production, indicating that ATF4 is a functional positive cellular factor in HIV-1 production. To determine the mechanism by which ATF4 regulates the HIV-1 life cycle, we assessed the effect of the overexpression of wild type ATF4 and its various derivatives on HIV-1 LTR-mediated transcriptional activation and the production of HIV-1 particles. This effect was studied through co-transfection experiments with either reporter vectors or proviral DNA. We found that the N-terminal domains of ATF4 are involved in HIV-1 LTR-mediated transcriptional activation, and thus in HIV-1 production.

• Korean Journal of Remote Sensing
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• v.27 no.4
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• pp.481-494
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• 2011

Investigation of the $CO_2$ exchange between biosphere and atmosphere at regional, continental, and global scales can be directed to combining remote sensing with carbon cycle process to estimate vegetation productivity. NASA Earth Observing System (EOS) currently produces a regular global estimate of gross primary productivity (GPP) and annual net primary productivity (NPP) of the entire terrestrial earth surface at 1 km spatial resolution. While the MODIS GPP algorithm uses meteorological data provided by the NASA Data Assimilation Office (DAO), the sub-pixel heterogeneity or complex terrain are generally reflected due to coarse spatial resolutions of the DAO data (a resolution of $1{\circ}\;{\times}\;1.25{\circ}$). In this study, we estimated inputs retrieved from MODIS products of the AQUA and TERRA satellites with 5 km spatial resolution for the purpose of finer GPP and/or NPP determinations. The derivatives included temperature, VPD, and solar radiation. Seven AmeriFlux data located in the Corn Belt region were obtained to use for evaluation of the input data from MODIS. MODIS-derived air temperature values showed a good agreement with ground-based observations. The mean error (ME) and coefficient of correlation (R) ranged from $-0.9^{\circ}C$ to $+5.2^{\circ}C$ and from 0.83 to 0.98, respectively. VPD somewhat coarsely agreed with tower observations (ME = -183.8 Pa ~ +382.1 Pa; R = 0.51 ~ 0.92). While MODIS-derived shortwave radiation showed a good correlation with observations, it was slightly overestimated (ME = -0.4 MJ $day^{-1}$ ~ +7.9 MJ $day^{-1}$; R = 0.67 ~ 0.97). Our results indicate that the use of inputs derived MODIS atmosphere and land products can provide a useful tool for estimating crop GPP.