• 한국주조공학회지
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• 제30권3호
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• pp.100-110
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• 2010

The solidification sequence and formation of intermetallic phase of Fe-rich Al-Si-Cu alloy were investigated by using real-time imaging of synchrotron X-ray radiation. Effects of cooling rate during uni-directional solidification on the resultant solidification behavior was also studied in a specially constructed vacuum chamber in the SPring-8 facility. The series of radiographic images were complementarily analyzed with conventional analysis of OM and SEM/EDX for phase identification. Detailed solidification sequence and formation mechanisms of various phases were discussed based on real-time image analysis. The growth rates of $\alpha$-AlFeMnSi and ${\beta}-Al_5FeSi$ were measured in order to understand the growth behavior of each phase. It is suggested that real-time imaging technique can be a powerful tool for the precise understanding of solidification behavior of various industrial materials.

• 대한한방부인과학회지
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• 제23권4호
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• pp.35-46
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• 2010

Purpose: This study was designed to investigate the effects of Cyperi Rhizoma (CR) on changes in weights morphological and histopathological observations in Polycystic Ovary(PCO) rats. Methods: PCO was induced by single intramuscular injection with EV(2mg) in female rats. Normal group(n=8) were injected with sesame oil and orally administrated distilled water for five weeks. PCO control group(n=8) were injected with EV and orally administrated distilled water for five weeks. CR treated group(n=8) were injected with EV and orally administrated CR for five weeks. Then we measured weight of body, ovaries. The histopathology changes of ovaries, and the expression of nerve growth factor(NGF) were also evaluated. Results: Single injection of EV induced suppression of weight gain, formation of cysts, increase of NGF expression. Oral administration of CR prevent suppression of weight gain shown in control group. In addition CR group showed upward tendency of ovarian size. Formation of cystic follicles induced by EV injection is suppressed by CR treatment. In additon, CR treatment lowered expression levels of nerve growth factor(NGF), which were elevated by induction of PCOS. Conclusion: These results suggest that CR can be used for patients with PCOS to prevent formation of cystic follicles and malfunction of ovary. And also suggest that the related mechanisms are involved in suppression of NGF expression.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.328-328
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• 2017

Drought is a major limiting factor that reduces rice production and occurs often especially under recent climate change. Plants have the ability to alter their developmental morphology in response to changing environment, which is known as phenotypic plasticity. In our previous studies, we found that one chromosome segment substitution line (CSSL50 derived from Nipponbare and Kasalath crosses) showed no differences in shoot and root growth as compared with the recurrent genotype, Nipponbare under non-stress condition but showed greater growth responses compared with Nipponbare under mild drought stress condition. We hypothesized that reducing root respiration as metabolic cost, which may be largely a consequence of aerenchyma formation would be one of the key mechanisms for root plasticity expression. This study aimed to evaluate the root respiration and aerenchyma formation under various soil moisture conditions among genotypes with different root plasticity. CSSL50 together with Nipponbare and Kasalath were grown under waterlogged conditions (Control) and mild drought stress conditions (20% of soil moisture content) in a plastic pot ($11cm{\times}14cm$, ${\varphi}{\times}H$) and PVC tube ($3cm{\times}30cm$, ${\varphi}{\times}H$). Root respiration rate was measured with infrared gas analyzer (IRGA, GMP343, Vaisala, Finland) with a closed static chamber system. There was no significant difference between genotypes in control for shoot and root growth as well as root respiration rate. In contrast, all the genotypes increased their root respiration rates in response to mild drought stress. However, CSSL50 showed lower root respiration rate than Nipponbare, which was associated by higher root aerenchyma formation that was estimated based on internal gas space (porosity) under mild drought stress conditions. Furthermore, there were significant negative correlations between root length and root respiration rate. These results imply that reducing the metabolic cost (= root respiration rate) is a key mechanism for root plasticity expression, which CSSL50 showed under mild drought.

• 한국세라믹학회지
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• 제35권5호
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• pp.505-511
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• 1998

단결정 Si 기판 위에 증착한 Co/Hf과 Co/Nb 이중층으로부터 형성된 Co 실리사이드의 성장기구에 대하여 조사하였다. 두 경우 모두 500$^{\circ}C$ 이상에서 CoSi2가 주로 형성되었으나 그 결정방위의 성장양상은 서로 달랐다. Co/Hf/(100)Si 구조에서는 Si 기판과 에피텍셜 관계를 갖는 결정립과 그렇지 않은 결정립이 서로 혼합되어 성장하였다. 그러나 Co/Nb/(100)Si에서는 처음부터 에피텍셜 관계를 갖지 않는 결정립들만이 형성되었다. 동일한 구조임에도 불구하고 이렇게 내열금속 중간층에 따라 성장된 실리사이드의 결정방위가 달라지는 것으 안정한 반응제어층의 형성 및 고온에서의 그 분해과정과 관련이 있었다. 여러 구성원소들로 이루어진 반응제어층이 고온까지 안정할 경우에는 Co의 확산이동을 균일하게 제어하여 실리사이드의 에피텍셜 성장이 가능하다.

• Asian Pacific Journal of Cancer Prevention
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• 제13권7호
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• pp.3275-3279
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• 2012

Recently, population-based studies of type 2 diabetes patients have provided evidence that metformin treatment is associated with a reduced cancer incidence and mortality, but its mode of action remains unclear. Here we report effects of metformin on hepatocellular carcinoma (HCC) Hep-G2 cells and details of molecular mechanisms of metformin activity. Our research indicates that metformin displays anticancer activity against HCC through inhibition of the mTOR translational pathway in an AMPK-independent manner, leading to G1 arrest in the cell-cycle and subsequent cell apoptosis through the mitochondrion-dependent pathway. Furthermore, we showed that metformin strongly attenuated colony formation and dramatically inhibited Hep-G2 tumor growth in vivo. In conclusion, our studies suggested that metformin might have potential as a cytotoxic drug in the prevention and treatment of HCC.

• 한국결정성장학회지
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• 제1권1호
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• pp.107-116
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• 1991

초음파 진동자를 사용 분무 열분해시켜 $Pb(NO_3)_2$와 $TiO(NO_3)_2$ 용액으로부터 $PbTiO_3$ 미분말을 합성하고 미립자의 특성을 조사하였다. 또한 미립자 형성과정을 같은 방법으로 합성되어 문헌에 보고된 $BaTiO_3$, $ZrO_2$, ZnO 등의 미립자 형성과정과 비교 검토하였다.

• The Korean Journal of Physiology and Pharmacology
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• 제22권5호
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• pp.555-566
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• 2018

Human umbilical cord blood mesenchymal stem cells (hUCB-MSCs) are used in tissue repair and regeneration; however, the mechanisms involved are not well understood. We investigated the hair growth-promoting effects of hUCB-MSCs treatment to determine whether hUCB-MSCs enhance the promotion of hair growth. Furthermore, we attempted to identify the factors responsible for hair growth. The effects of hUCB-MSCs on hair growth were investigated in vivo, and hUCB-MSCs advanced anagen onset and hair follicle neogeneration. We found that hUCB-MSCs co-culture increased the viability and up-regulated hair induction-related proteins of human dermal papilla cells (hDPCs) in vitro. A growth factor antibody array revealed that secretory factors from hUCB-MSCs are related to hair growth. Insulin-like growth factor binding protein-1 (IGFBP-1) and vascular endothelial growth factor (VEGF) were increased in co-culture medium. Finally, we found that IGFBP-1, through the co-localization of an IGF-1 and IGFBP-1, had positive effects on cell viability; VEGF secretion; expression of alkaline phosphatase (ALP), CD133, and ${\beta}-catenin$; and formation of hDPCs 3D spheroids. Taken together, these data suggest that hUCB-MSCs promote hair growth via a paracrine mechanism.

• 대한한방부인과학회지
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• 제25권2호
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• pp.66-77
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• 2012

Objectives: This study was designed to investigate the effects of PR on ovarian tissue in PCOS rats through measurement of morphological and histo-pathological observations, ovarian size. In addition, effects on expression levels of Insulin like Growth Factor Receptor(IGFR) were also investigated to elucidate related mechanisms. Methods: PCOS was induced by single intermuscular injection with ${\beta}$-Estradiol 17-Valerate(EV) in female rats. Normal group(NOR, n=8) were injected with sesame oil and administrated hard food for five weeks. Control group(CTL, n=8) were injected with EV and administrated hard food for five weeks. CR group(n=8) were injected with EV and administrated hard food mixed CR for five weeks. Then, we measured weights of body and ovary, uptakes of food and water. And we observed morphological and histo-pathological changes of ovary, levels of IGFR. Results: In this experiments, single injection of Estradiol Valerate(EV) induced suppression of weight gain, formation of cysts, increase of IGFR expression. Oral administration of PR prevent decrease of ovarian size significantly. Further more, formation of cystic follicles induced by EV injection is suppressed by PR treatment. Conclusions: These results suggest PR can be used for patients with PCOS to prevent formation of cystic follicles and malfunction of ovary.

• Journal of Ginseng Research
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• 제47권3호
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• pp.469-478
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• 2023

Background: Nitrogen (N) is an essential macronutrient for plant growth and development. To support agricultural production and enhance crop yield, two major N sources, nitrate and ammonium, are applied as fertilizers to the soil. Although many studies have been conducted on N uptake and signal transduction, the molecular genetic mechanisms of N-mediated physiological roles, such as the secondary growth of storage roots, remain largely unknown. Methods: One-year-old P. ginseng seedlings treated with KNO₃ were analyzed for the secondary growth of storage roots. The histological paraffin sections were subjected to bright and polarized light microscopic analysis. Genome-wide RNA-seq and network analysis were carried out to dissect the molecular mechanism of nitrate-mediated promotion of ginseng storage root thickening. Results: Here, we report the positive effects of nitrate on storage root secondary growth in Panax ginseng. Exogenous nitrate supply to ginseng seedlings significantly increased the root secondary growth. Histological analysis indicated that the enhancement of root secondary growth could be attributed to the increase in cambium stem cell activity and the subsequent differentiation of cambium-derived storage parenchymal cells. RNA-seq and gene set enrichment analysis (GSEA) revealed that the formation of a transcriptional network comprising auxin, brassinosteroid (BR)-, ethylene-, and jasmonic acid (JA)-related genes mainly contributed to the secondary growth of ginseng storage roots. In addition, increased proliferation of cambium stem cells by a N-rich source inhibited the accumulation of starch granules in storage parenchymal cells. Conclusion: Thus, through the integration of bioinformatic and histological tissue analyses, we demonstrate that nitrate assimilation and signaling pathways are integrated into key biological processes that promote the secondary growth of P. ginseng storage roots.

• Molecules and Cells
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• 제20권2호
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• pp.263-270
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• 2005

Transactivation of EGF-receptor (EGFR) by G-protein coupled receptors (GPCRs) is emerging as an important pathway in cell proliferation, which plays a crucial role in the development of atherosclerotic lesion. Angiotensin II (Ang II) has been identified to have a major role in the formation of atherosclerotic lesions, although the underlying mechanisms remain largely unclear. We hypothesize that Ang II promotes the proliferation and migration of smooth muscle cells through the release of heparin-binding epidermal growth factor like growth factor (HB-EGF), transactivation of EGFR and activation of Akt and Erk 1/2, with matrix metalloproteases (MMPs) playing a dispensable role. Primary rat aortic smooth muscle cells were used in this study. Smooth muscle cells rendered quiescent by serum deprivation for 12 h were treated with Ang II (100 nM) in the presence of either GM6001 ($20{\mu}M$), a specific inhibitor of MMPs or AG1478 ($10{\mu}M$), an inhibitor of EGFR. The levels of phosphorylation of EGFR, Akt and Erk 1/2 were assessed in the cell lysates. Inhibition of MMPs by GM6001 significantly attenuated Ang II-stimulated phosphorylation of EGFR, suggesting that MMPs may be involved in the transactivation of EGFR by Ang II receptor. Furthermore Ang II-stimulated proliferation and migration of smooth muscle cells were significantly blunted by inhibiting MMPs and EGFR and applying HB-EGF neutralization antibody, indicating that MMPs, HB-EGF and EGFR activation is necessary for Ang-II stimulated migration and proliferation of smooth muscle cells. Our results suggest that inhibition of MMPs may represent one of the strategies to counter the mitogenic and motogenic effects of Ang II on smooth muscle cells and thereby prevent the formation and development of atherosclerotic lesions.