• Molecules and Cells
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• v.24 no.3
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• pp.424-430
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• 2007

The biological effects of low-dose radiation have been investigated and debated for more than a century, but its cellular effects and regulatory mechanisms remain poorly understood. This study shows the human cellular responses to low-dose radiation in CCD-18 Lu cells, which are derived from normal human lung fibroblasts. We examined a colony-forming assay for cell survival by ionizing radiation. Live cell counting and cell cycle analysis were measured for cell proliferation and cell cycle progression following low-dose irradiation. We examined Raf and Akt phosphorylation to determine the proliferation mechanism resulting from low-dose radiation. We also observed that p53 and p21 were related to cell cycle response. We found that 0.05 Gy of ionizing radiation enhanced cell proliferation and did not change the progression of the cell cycle. In addition, 0.05 Gy of ionizing radiation transiently activated Raf and Akt, but did not change phospho-p53, p53 and p21 in CCD-18 Lu cells. However, 2 Gy of ionizing radiation induced cell cycle arrest, phosphorylation of p53, and expression of p53 and p21. The phosphorylation of Raf and Akt proteins induced by 0.05 Gy of ionizing radiation was abolished by pre-treatment with an EGFR inhibitor, AG1478, or a PI3k inhibitor, LY294002. Cell proliferation stimulated by 0.05 Gy of ionizing radiation was blocked by the suppression of Raf and Akt phosphorylation with these inhibitors. These results suggest that 0.05 Gy of ionizing radiation stimulates cell proliferation through the transient activation of Raf and Akt in CCD-18 Lu cells.

• BMB Reports
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• v.28 no.5
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• pp.414-419
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• 1995

The retroviruses carrying ${\nu}-myc$ and ${\nu}-raf$ oncogenes were infected into fetal thymic organ culture (FTOC) to study the molecular mechanisms involved in T cell development. T cell lymphomas in the different stages of T cell development were obtained from this culture system. Interestingly, a few cell lines obtained from this system have a lack of transfected oncogenes, however these cells have the characteristics of transformed cells. In spite of the discrete phenotype of these transformed cell lines, the same pattern of recombination of endogenous c-raf genes was detected from Southern blot analysis. We suggest in this regard that the translocation event of thymocytes, or abnormal promoter activity, can cause lymphomagenesis by way of c-raf.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.319-319
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• 2023

Flows of water in the environment (e.g. in a river or estuary) generally occur in complex conditions. This complexity can hinder a general understanding of flows and their related sedimentary processes, such as erosion and deposition. To gain insight in simplified, controlled conditions, hydraulic flumes are a popular type of laboratory research equipment. Linear flumes use pumps to recirculation water. This isn't appropriate for the investigation of cohesive sediments as pumps can break fragile cohesive sediment flocs. To overcome this limitation, the rotating annular flume (RAF) was developed. While not having pumps, a side-effect is that unwanted secondary circulations can occur. To counteract this, the top and bottom lid rotate in opposite directions. Furthermore, a larger flume is considered better as it has less curvature and secondary circulation. While only a few RAFs exist, they are important for theoretical research which often underlies numerical models. Many of the first-generation of RAFs have come into disrepair. As new measurement techniques and models become available, there is still a need to research cohesive sediment erosion and deposition in facilities such as a RAF. New RAFs also can have the advantage of being automatic instead of manually operated, thus improving data quality. To further advance our understanding of cohesive sediment erosion and deposition processes, a large, automatic RAF (1.72 m radius, 0.495 m channel depth, 0.275 m channel width) has been constructed at the Hydraulic Laboratory at Chungnam National University (CNU), Korea. The RAF has the ability to simulate both unidirectional (river) and bidirectional (tide) flows with supporting instrumentation for measuring turbulence, bed shear stress, suspended sediment concentraiton, floc size, bed level, and bed density. Here we present the current status and future prospect of the CNU RAF. In the future, calibration of the rotation rate with bed shear stress and experiments with unidirectional and bidirectional flow using cohesive kaolinite are expected. Preliminary results indicate that the CNU RAF is a valuable tool for fundamental cohesive sediment transport research.

• Korean Journal of Microbiology
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• v.42 no.3
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• pp.223-229
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• 2006

To develop multifunctional microbial inoculant, an insluble phosphate-solubilizing bacterium with antifungal activity was isolated from plant rhizospheric soil. On the basis of its morphological, cultural and physiological characteristics and Biolog analysis, this bacterium was identified as Pseudomonas fluorescens RAF15. P. fluorescens RAF15 showed antifungal activities against phytopathogenic fungi Botrytis cinerea and Rhizoctonia solani. The optimal medium composition and cultural conditions for the solubilization of insoluble phosphate by P. fluorescens RAF15 were 1.5% of glucose, 0.005% of urea, 0.3% $MgCl_2{\cdot}6H_2\;0.01%\;of\;MgSO_4{\cdot}7H_2O\;0.01%,\;of\;CaCl_2{\cdot}2H_2O$, and 0.05% of NaCl along with initial pH 7.0 at $30^{\circ}C$. The soluble phosphate production under optimum condition was 863 mg/L after 5 days of cultivation. The solubilization of insoluble phosphates was associated with a drop in the pH of the culture medium. P. fluorescens RAF15 showed resistance against different environmental stresses like $10-35^{\circ}C$ temperature, 1-4% salt concentration and pH 2-11 range. The strain produced soluble phosphate to the culture broth with the concentrations of 971-1121 mg/L against $CaHPO_4$, 791-908 mg/L against $Ca_3(PO_4){_2}$, and 844 mg/L against hydroxyapatite, respectively. However, the strain produced soluble phosphate to the culture broth with the concentrations of 15 mg/L against $FePO_4$, and 5 mg/L against $AlPO_4$, respectively.

• Proceedings of the Korea Environmental Mutagen Society Conference
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• 2002.11a
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• pp.136-136
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• 2002

• Journal of Society of Preventive Korean Medicine
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• v.4 no.2
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• pp.235-241
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• 2000

This study was carried out to evaluate cytotoxic effects of Poncirus trifoliata Raf. extract on lymphocytic leukemia tumor (L1210) cell lines. Disruptions in cell organelles were determined by 3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl-2H-tetrazoliumbromide (MTT) assay The comparison of Ic50 Values of Poncirus trifoliata Raf. extract in L1210 cell lines showed that their susceptibility to these fractons decreased in the following order: adriamycin > Fr.4> Fr. 6> Fr. 5> Fr. 3> Fr. 1> Fr. 2 by the MTT assay. In order to develop an antumicrobial agent, Poncirus trifoliata Raf. was extracted wit ethanol, and then it was fractionated with several mobile phase. The antitumor activities of fractions of the ethanol soluble extract was investigated. The minimal inhibitory concentrations (MIC) of fractions of the ethanol soluble extract of Poncirus trifoliata Raf. against microorganisms were also examined. Antimicrobial activities of ampicillin and ketoconazole as references were compared to those of fractions of the ethanol soluble extract of Poncirus trifoliata Raf. The antimicrobial activities of all fractions from the extract had growth inhibition activities against gram-positive bacteria, gram-negative bacteria and fungi $(MIC\;>\;200{\mu}g/ml)$. These results suggest that fraction 4 of the ethanol soluble extract of Poncirus trifoliata Raf. possessed the most antitumorous agent.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.43 no.2
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• pp.66-71
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• 2011

Biocomposites were fabricated with biodegradable polymers and natural fibers. Biocomposites have benefits of low cost, low density, and biodegradability over inorganic fiber composite, and give comparable strength properties. Hydrophobic polymer used for sizing in paper industry, AKD (Akenyl Keten Dimer), was applied to natural fibers, red algae fibers (RAF) in this study, to make fiber surfaces more compatible to hydrophobic nature of matrix polymers. Composites with RAF, kenaf, glass fibers, and carbon fibers have been fabricated by a compression molding method and their thermo-mechanical properties have been studied. Also, the thermal dimensional stability test was done from at 30 to $100^{\circ}C$. The storage moduli and the thermo-mechanical stabilities of polypropylene and poly lactic acid based biocomposites were improved by reinforcing with the RAF and much more with AKD treated fibers. Dimensional stability of biocomposite was also markedly improved by AKD pretrement on RAF.

• Korean Journal of Plant Taxonomy
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• v.39 no.3
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• pp.233-236
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• 2009

The genus Triodanis Raf. ex Greene (Campanulaceae), which is native to America, is newly reported for Korea based on the discovery of T. perfoliata (L.) Nieuwl in the lowlands of Donneko, Seogwipo-si, Jeju-do. The common name 'Bi-neo-seu-geo-ul-sok' is given for the genus and 'Bi-neo-seu-do-ra-ji' for the species. The morphological characters of the genus and species, and illustrations of the species are provided along with photographs of its habitat.

• Proceedings of the Korean Society of Toxicology Conference
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• 2005.05a
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• pp.121-121
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• 2005

• Clinical and Experimental Pediatrics
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• v.62 no.7
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• pp.274-280
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• 2019

Purpose: To analyze the growth response to growth hormone (GH) therapy in prepubertal patients with Noonan syndrome (NS) harboring different genetic mutations. Methods: Twenty-three patients with prepubertal NS treated at Pusan National University Children's Hospital between March 2009 and July 2017 were enrolled. According to the disease-causing genes identified, the patients with NS were divided into 4 groups. Three groups were positive for mutations of the PTPN11, RAF1, and SOS1 genes. The five genes undetected (FGU) group was negative for PTPN11, RAF1, SOS1, KRAS, and BRAF gene mutations. The influence of genotype was retrospectively analyzed by comparing the growth parameters after GH therapy. Results: The mean chronological age at the start of GH treatment was $5.85{\pm}2.67years$. At the beginning of the GH treatment, the height standard deviation score (SDS), growth velocity (GV), and lower levels of insulin-like growth factor-1 (IGF)-1 levels were not statistically different among the groups. All the 23 NS patients had significantly increased height SDS and serum IGF-1 level during the 3 years of treatment. GV was highest during the first year of treatment. During the 3 years of GH therapy, the PTPN11, RAF1, and SOS1 groups showed less improvement in height SDS, IGF-1 SDS, and GV, and less increase in bone age-to-chronological age ratio than the FGU group. Conclusion: The 3-year GH therapy in the 23 prepubertal patients with NS was effective in improving height SDS, GV, and serum IGF-1 levels. The FGU group showed a better response to recombinant human GH therapy than the PTPN11, RAF1, and SOS1 groups.