• The Korean Journal of Financial Management
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• v.26 no.1
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• pp.1-29
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• 2009

As foreign investors' share holdings in Korean firms have dramatically increased since 1998 following the financial deregulation on the limit of foreign stock investment, the concern over the negative impacts the foreign investors would bring on the firms' financial policy has been growing too. Foreign investors were perceived to require the firms of excessive payments of cash dividends sometimes with threat of hostile takeover trials detering the firm from investing its cash flow in the physical facilities and RandD eroding their potential growth capabilities. We examine the impact of foreign investment on the firms' dividend policy using 234 listed firms' panel data over the sample periods of 1998 to 2005 employing various panel regression methodology. Foreign shareholders are found not to be related or even negatively related to the payout ratio(dividend/net income), but positively and statistically significantly related to the ratio of cash dividends to book of asset, negatively to the dividend yields. Considering the payout ratio is the most appropriate measure for the dividend payment, we can not support the arguments that the foreign investors' holdings have induced the excessive dividend level in Korean firms.

• Fisheries and Aquatic Sciences
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• v.14 no.4
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• pp.267-274
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• 2011

Bacterial lipopolysaccharide (LPS) induces expression of pro-inflammatory cytokines and enzymes producing nitric oxide (NO) and prostaglandins (PGs) in immune cells. This process is mediated by the activation of nuclear factor kappaB (NF-${\kappa}B$). In this study, we investigated the anti-inflammatory characteristics of Codium fragile ethanolic extract (CFE) mediated by the regulation of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) using LPS-stimulated murine macrophage RAW 264.7 cells. CFE significantly inhibited LPS-induced NO and $PGE_2$ production in a dose-dependent manner and suppressed the expression of iNOS and COX-2 proteins in LPS-stimulated RAW 264.7 cells with no cytotoxicity. Pro-inflammatory cytokines, such as interleukin (IL)-$1{\beta}$, IL-6, and tumor necrosis factor-${\alpha}$, were significantly reduced by treatment of CFE in LPS-stimulated RAW 264.7 cells. CFE inhibited the promoter activity of (NF)-${\kappa}B$ in LPS-stimulated macrophages. Treatment with CFE suppressed translocation of the NF-${\kappa}B$ p65 subunit by preventing proteolytic degradation of inhibitor of ${\kappa}B-{\alpha}$. These results indicate that the CFE-mediated inhibition of NO and $PGE_2$ production in LPS-stimulated RAW 264.7 cells is mediated through the NF-${\kappa}B$-dependent transcriptional downregulation of iNOS and COX-2, suggesting the potential of CFE as a nutraceutical with anti-inflammatory activity.

• Journal of Microbiology and Biotechnology
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• v.23 no.6
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• pp.794-801
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• 2013

This paper reports the production and characterization of crude xylanase from the newly isolated Humicola sp. Ly01. The highest (41.8 U/ml) production of the crude xylanase was obtained under the optimized conditions (w/v): 0.5% wheat bran, 0.2% $KH_2PO_4$, and 0.5% peptone; initial pH 7.0; incubation time 72 h; $30^{\circ}C$; and 150 rpm. A considerable amount of the crude xylanase was induced using hulless barley bran or soybean meal as the carbon source, but a small amount of the enzyme was produced when supplementary urea was used as the nitrogen source to wheat bran. The crude xylanase showed apparent optimal cellulase-free xylanase activity at $60^{\circ}C$ and pH 6.0, more than 71.8% of the maximum xylanase activity in 3.0-30.0% (v/v) ethanol and more than 82.3% of the initial xylanase activity after incubation in 3.0-30.0% (v/v) ethanol at $30^{\circ}C$ for 2 h. The crude xylanase was moderately resistant to both acid and neutral protease digestion, and released 7.9 and 10.9 ${\mu}mol/ml$ reducing sugar from xylan in the simulated gastric and intestinal fluids, respectively. The xylooligosaccharides were the main products of the hydrolysis of xylan by the crude xylanase. These properties suggested the potential of the crude enzyme for being applied in the animal feed industry, xylooligosaccharides production, and high-alcohol conditions such as ethanol production and brewing.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.11
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• pp.1054-1062
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• 2010

Oxidative coupling reactions of humic substances (HS) can be catalyzed by a variety of natural extracellular enzymes and metal oxides. In this study, property changes of HS induced by a natural enzyme, horseradish peroxidase (HRP), and the effect of it to microfiltration (MF) were investigated. PAHA was transformed by oxidative coupling reaction with HRP and hydrogen peroxide ($H_2O_2$), verifying the catalytic effects of the HRP. Size exclusion chromatography (SEC) revealed that weight-average molecular weight (MWw) of PAHA was proportionally increased with the dosages of HRP and $H_2O_2$, indicating the transform action of HS into larger and complex molecules. An increase in the conformational stability of HS was achieved through the promotion of intermolecular covalent bondings between heterogeneous humic molecules. Spectroscopic analysis (fluorescence and infrared spectroscopy) proved that functional groups were transformed by the reaction. Additionally, HS and transformed products were undergone microfiltration (MF) to examine the treatment potential of them in a water treatment facility. Original HS could not be removed by MF but larger molecules of transformed products could be removed. Meanwhile, transformed products caused more fouling on the filtration than original HS. This results proved that natural organic matter (NOM) can be removed by MF after its increase in molecular size by oxidative coupling reaction.

• Development and Reproduction
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• v.13 no.4
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• pp.227-237
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• 2009

Recently, adipose mesenchymal stem cells (AdMSC) that are similar to bone marrow MSC and blood derived MSC are thought to be another source for stem cell therapy. However, the diseases that can be applied for stem cells therapy are age-dependent degenerative diseases. Accordingly, the present study investigated the growth and differentiation potential to neural cells of human AdMSC (hAdMSC) obtained from aged thirty, forty and fifty. The growth of cells and cell viability were measured by passage and neural differentiation of hAdMSC was induced in neural differentiation condition for 10 days. Our results demonstrated that cell number, viability and morphology were not different from hAdMSC by age and passage. Immunofluorescence analysis of neural cell marker (TuJ1, NSE, Sox2, GFAP or MAP2) demonstrated no significant differences in neural cell differentiation by age and passage. As the number of passage was increased, the mRNA level of MAP2 and Sox2 was decreased in hAdMSC from age of 50 compared to hAdMSC from age of 30. In conclusion, the present study demonstrated that ability of neural cell differentiation of hAdMSC was maintained with ages, suggesting that autologous stem cells from aged people can be applied for stem cell therapy with age-dependent neural disease with the same stem cell quality and ability as stem cell derived from young age.

• Development and Reproduction
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• v.22 no.2
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• pp.155-163
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• 2018

This study aimed to investigate changes in the activity and mRNA expression of plasminogen activators (PAs) induced by $17{\beta}$-estradiol ($E_2$), human chorionic gonadotropin (hCG), and interleukin-$1{\beta}$ ($IL-1{\beta}$) in porcine endometrial cells. Endometrial cells were isolated from the epithelium and cultured to 80% confluence. They were then treated for 24 h with $E_2$ (0.2, 2, 20, and 200 ng/mL), $IL-1{\beta}$ (0.1, 1, 10, and 100 ng/mL), and hCG (0.5, 1, 1.5 and 2 IU/mL). mRNA expressions of urokinase-type (uPA) and tissue-type (tPA) PAs were analyzed using reverse transcription PCR, and activities were measured using a PA activity assay. mRNA expressions of uPA and tPA increased with $E_2$ treatment; however, this was not significant. Similarly, treatment with hCG did not influence the mRNA expressions of PAs. Interestingly, treatment with 0.1 ng/mL $IL-1{\beta}$ significantly reduced the mRNA expression of uPA, but did not affect that of tPA. Treatment with 2, 20, and 200 ng/mL $E_2$ increased PA activity compared with the control group; treatment with 0.1 and 1 ng/mL $IL-1{\beta}$ significantly increased PA activity compared with the other $IL-1{\beta}$ treatment groups, whereas treatment with 10 and 100 ng/mL $IL-1{\beta}$ decreased. Treatment with 2 IU/mL hCG increased PA activity compared with the other treatment groups, although there were no significant differences between the hCG and control groups. In conclusion, the activity and mRNA expression of PAs were differently regulated by the hormone/cytokine and its concentration in porcine endometrial cells. Therefore, understanding PA regulatory mechanisms may help to improve the reproductive potential of domestic animals.

• Reproductive and Developmental Biology
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• v.39 no.3
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• pp.77-81
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• 2015

This study was carried out to evaluate the effects of embryonic stage and toxicities of cryoprotectant on the rates of survival and development of the cryopreserved mouse early embryo and finally to establish the cryopreservation method of surplus embryos obtained during assisted reproductive technology. Toxicities of two cryoprotectants, dimethyl sulfoxide (DMSO) and ethylene glycol (EG) were investigated using a murine embryo model. Female F-1 mice were stimulated with gonadotropin, induced ovulation with hCG and mated. Two cell embryos were collected and cultured after exposure to either DMSO or EG. Embryo development was evaluated up to the blastocyst stage. The total cell count of blastocysts that were treated with DMSO ($68.1{\pm}24.1$) at the 2-cell stage was significantly lower than that were treated with EG ($81.2{\pm}27.0$) or the control ($99.0{\pm}18.3$) (p<0.001). On comparison of two cryoprotectant treated groups, the DMSO treated group showed a decreased cell count compared with the EG treated group (p<0.05). Both DMSO ($15.4{\pm}1.5$) and EG ($10.2{\pm}1.4$) treated groups showed higher apoptosis rates of cells in the blastocyst compared with the control ($6.1{\pm}0.9$, p<0.0001). In addition, the DMSO treated group showed more apoptotic cells than the EG treated group (p<0.001). The potential toxicity of cryoprotectants was uncovered by prolonged exposure of murine embryos to either DMSO or EG at room temperature. When comparing two cryoprotective agents, EG appeared to be less toxic than DMSO at least in a murine embryo model.

• Tunnel and Underground Space
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• v.23 no.1
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• pp.13-30
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• 2013

Increase of pore fluid pressure resulting from injection of $CO_2$ may reactivate pre-existing faults, and the induced seismic activities can raise the safety issues such as seal integrity, restoration of storage capacity, and, in the worst case, removal of previously injected $CO_2$. Thus, fault stability and potential for $CO_2$ leakage need to be assessed at the stage of site selection and planning of injection pressure, based on the results of large-scale site investigations and numerical modeling for various scenarios. In this report, studies on the assessment of fault stability during injection of $CO_2$ were reviewed. The seismic activities associated with an artificial injection of fluids or a release of naturally trapped high-pressure fluids were first examined, and then site investigation methods for the magnitude and orientation of in situ stresses, the distribution and change of pore fluid pressure, and the location of faults were generally summarized. Recent research cases on possibility estimation of fault reactivation, prediction of seismic magnitude, and modeling of $CO_2$ leakage through a reactivated fault were presented.

• Journal of Veterinary Clinics
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• v.26 no.5
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• pp.445-449
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• 2009

For human organ transplantations, histidine-tryptophan-ketoglutarate solution (HTKS) and University of Wisconsin solution (UWS) have been shown to engender similar outcomes as gold standard cold preservation solutions ($4^{\circ}C$). To select the effective preservation solution for cold storage of kidney xenografts in miniature pig, which could be a potential source animal of bio-organs, this study compared early histopathological outcomes of cold preservation injury using HTKS and UWS. Twelve miniature pigs weighing 25.6 to 34.7 kg were divided into two groups (n = 6 per group), UWS group and HTKS group. The kidneys in each group were harvested, cold flushed, and preserved for 0, 24, 48, and 72 hrs at $4^{\circ}C$ with UWS or HTKS, respectively. Histolopathological examinations were assessed on kidney biopsy specimens, taken after each cold storage. The degree of renal injury was scored using 5 different criteria (pyknotic nuclei, disruption of cytoplasm, detachment of epithelium, loss of microvilli, tubular necrosis and loss of glomerular tufts) of the cellular components of the tissue. The degree of kidney damage was increased with prolonged cold ischemia time. UWS and HTKS have at least similar efficacy in kidney preservation within 24 hrs cold preservation time. However, in HTKS group cold-induced injury started to be observed more than in UWS group after 48 hrs of cold storage. In conclusion, UWS and HTKS were equally effective for cold preservation of miniature pig kidney in early preservation times; however, UWS may be more effective at longer preservation times as compared to HTKS.

• Parasites, Hosts and Diseases
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• v.52 no.1
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• pp.93-97
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• 2014

Subolesin (4D8), the ortholog of insect akirins, is a highly conserved protective antigen and thus has the potential for development of a broad-spectrum vaccine against ticks and mosquitoes. To date, no protective antigens have been characterized nor tested as candidate vaccines against Dermacentor silvarum bites and transmission of associated pathogens. In this study, we cloned the open reading frame (ORF) of D. silvarum 4D8 cDNA (Ds4D8), which consisted of 498 bp encoding 165 amino acid residues. The results of sequence alignments and phylogenetic analysis demonstrated that D. silvarum 4D8 (Ds4D8) is highly conserved showing more than 81% identity of amino acid sequences with those of other hard ticks. Additionally, Ds4D8 containing restriction sites was ligated into the pET-32(a+) expression vector and the recombinant plasmid was transformed into Escherichia coli rosetta. The recombinant Ds4D8 (rDs4D8) was induced by isopropyl ${\beta}$-D-thiogalactopyranoside (IPTG) and purified using Ni affinity chromatography. The SDS-PAGE results showed that the molecular weight of rDs4D8 was 40 kDa, which was consistent with the expected molecular mass considering 22 kDa histidine-tagged thioredoxin (TRX) protein from the expression vector. Western blot results showed that rabbit anti-D. silvarum serum recognized the expressed rDs4D8, suggesting an immune response against rDs4D8. These results provided the basis for developing a candidate vaccine against D. silvarum ticks and transmission of associated pathogens.