• Investigative Magnetic Resonance Imaging
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• v.19 no.1
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• pp.31-36
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• 2015

Purpose: To compare the depiction of brain metastases on contrast-enhanced images with 7.0 tesla (T) and at 1.5T MRI. Materials and Methods: Four consecutive patients with brain metastases were scanned on 7.0T whole-body scanner and 1.5T MRI. A 3D T1-weighted gradient echo sequence (3D T1-GRE) at 1.5T (voxel size = $0.9{\times}0.9{\times}1.5mm^3$ after double-dose, gadoterate meglumine, Gd-DOTA) was compared to a 7.0T 3D T1-GRE sequence (voxel size = $0.4{\times}0.4{\times}0.8mm^3$, single-dose Gd-DOTA) in four patients after a 5 minute delay. The number of contrast-enhancing metastases in MPRAGE images was compared in each patient by two radiologists in consensus. We measured contrast ratio of enhancing brain metastases and white matter in 1.5T and 7.0T. Results: In all four patients 7.0T 3D T1-GRE images after single-dose Gd-DOTA and 1.5T after double-dose Gd-DOTA depicted 11 brain metastases equally. In the quantitative analysis of contrast ratios of enhancing brain metastases and white matter, the 1.5T 3D T1-GRE after double-dose showed an increased contrast ratio compared to 7.0T 3D T1-GRE after single-dose ($0.961{\pm}0.571$ versus $0.885{\pm}0.494$; n = 11 metastases). But this difference was not statistically significant (P = 0.711). Conclusion: Our preliminary results indicate that 7.0T single-dose Gd-enhanced images were not different to 1.5T double-dose Gd-enhanced images for the detection of brain metastases.

• Journal of Life Science
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• v.28 no.11
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• pp.1277-1284
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• 2018

In this study, a repeated yeast integrative plasmid (R-YIp) harboring Cre/loxP system was constructed to integrate various gene expression cassettes into the yeast chromosome. The R-YIp system contains a reusable selective marker (CgTRP1), loxP sequence, and target sequence for integration. Therefore, many gene expression cassettes can be integrated into the same position of the same yeast chromosome. In the present study, several model enzymes involving xylan/xylose metabolism were examined, including endoxylanase (XYLP), ${\beta}$-xylosidase (XYLB), xylose reductase (GRE3) and xylitol dehydrogenase (XYL2). Efficient expression of these genes was obtained using two promoters (GAL10p and ADH1p) and various plasmids (pGMF-GENE and pAMF-GENE plasmids) were constructed. The XYLP, XYLB, GRE3, and XYL2 genes were efficiently expressed under the control of the GAL10 promoter. Subsequently, R-YIps containing the GAL10p-GENE-GAL7t cassette were constructed, resulting in pRS-XylP, pRS-XylB, pRS-Gre3, and pRS-Xyl2 plasmids. These plasmids were sequentially integrated into chromosome VII of a Saccharomyces cerevisiae strain by repeated gene integration and selective marker rescue. These genes were integrated by the R-YIp system and were stably expressed in the yeast transformants to produce active recombinant enzymes. Therefore, we expect that the R-YIp system will be able to overcome current limitations of the host cells and allow selective marker selection for the integration of various genes into the yeast chromosome.

• Proceedings of the KSMRM Conference
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• 1998.03a
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• pp.1-11
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• 1998

• Journal of Ginseng Research
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• v.21 no.3
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• pp.141-146
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• 1997

The role of cAMP in the differentiation process of F9 cells induced by ginsenosides was examined by performing transient transfixion assay with CRE-luciferase reporter plasmid, GR thansactivation assay with GRE-luciferase activity with or without treatment of CAMP and forskolin, an activator of adenylate cyclase, and protein klnase A assay in the presence of ginsenosides. Ginsenosides had no effect on CRE-transactivation activity, whereas retinoic acid induced the activity. When cAMP or forskolin was treated with ginsenosides, GRE-luciferase activity was further augumented by them. In addition, ginsenosides induced protein kinase A activity in the presence of cAMP. These results suggest that ginsenosides activate cAMP-dependent protein kinase A which, in turn, increase GR activity in F9 cells.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.3
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• pp.93-101
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• 2002

The effect of nonlinear friction in the low velocity is dominant in precise controlled mechanisms and it is difficult to identify the friction effect. The friction model which Canudas suggested so called, LuGre model is well expressed the friction effect as Streibeck in the law velocity. But it\`s model parameters were estimated continuously in operation for precise control. This paper suggests the sliding mode controller and observer for compensating the friction effect. Experimental results for a ball-screw system show that the proposed method has a good performance especially in the low velocity.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.3
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• pp.394-401
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• 2010

In this article, we investigate a robust friction compensation scheme for the purpose of accomplishing precision positioning performance a servo mechanical system with nonlinear dynamic friction. To estimate the friction state and tackle robustness problem for uncertainty, a RFNN and reconstructed error compensator as well as a robust friction state observer are developed. The asymptotic stability of the series of friction compensation methodologies are verified from the Lyapunov's stability theory. Some simulations and experiments on a servo mechanical system were carried out to evaluate the effectiveness of the proposed control scheme.

• Korean Journal of Plant Taxonomy
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• v.46 no.4
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• pp.337-347
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• 2016

Based on genetic studies and palaeoecological surveys, the main Korean mountain range, the so-called "Baekdudaegan" (BDDG), has been recently suggested to be a major glacial refugium at the Last Glacial Maximum (LGM) for the boreal and temperate flora of northeastern Asia. On the basis of its shared role as a glacial refugium, and on a series of striking similarities in floristic richness and orographic features, the BDDG would constitute a sort of "eastern counterpart" of the Southern Appalachians. Given its floristic, biogeographic, and cultural value, the BDDG merits high priority for conservation.

• Journal of Marine Bioscience and Biotechnology
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• v.2 no.2
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• pp.81-85
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• 2007

Glucocorticoid hormone regulates numerous physiological processes, such as regulation of metabolism, and anti-inflammatory and immunosuppressive actions via the activation and repression of gene expression. Here we described a lentivirus-based reporter vector system expressing red fluorescent protein (mRFP) or firefly luciferase (Luc) under the control of a glucocorticoid-responsive element that allows observation of the temporospatial pattern of glucocorticoid induced GR-mediated signaling on a cellular level. Moreover, usage of the chromatin insulator of the chicken ${\beta}$-globin locus induced a marked increase of sensitivity of glucocorticoid inducible promoter of a reporter gene. Use of this method will be applicable of screening for agonist and antagonist of GR in vitro, and also a reporter gene assay for the in vivo determination of the GR-mediated gene activation.

• Investigative Magnetic Resonance Imaging
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• v.15 no.1
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• pp.11-21
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• 2011

Purpose : Localization using MRI is difficult due to susceptibility induced artifacts caused by metal electrodes. Here we took an advantage of the B0 pattern induced by the metal electrodes by using an oblique-view imaging method. Materials and Methods : Metal electrode models with various diameters and susceptibilities were simulated to understand the aspect of field distortion. We set localization criteria for a turbo spin-echo (TSE) sequence usingconventional ($90^{\circ}$ view) and $45^{\circ}$ oblique-view imaging method through simulation of images with various resolutions and validated the criteria usingphantom images acquired by a 3.0T clinical MRI system. For a gradient-refocused echo (GRE) sequence, which is relatively more sensitive to field inhomogeneity, we used phase images to find the center of electrode. Results : There was least field inhomogeneity along the $45^{\circ}$ line that penetrated the center of the electrode. Therefore, our criteria for the TSE sequence with $45^{\circ}$ oblique-view was coincided regardless of susceptibility. And with $45^{\circ}$ oblique-view angle images, pixel shifts were bidirectional so we can detect the location of electrodes even in low resolution. For the GRE sequence, the $45^{\circ}$ oblique-view anglemethod madethe lines where field polarity changes become coincident to the Cartesian grid so the localization of the center coordinates was more facilitated. Conclusion : We suggested the method for accurate localization of electrode using $45^{\circ}$ oblique-view angle imaging. It is expected to be a novelmethodto monitoring an electrophysiological brain study and brain neurosurgery.

• Microbiology and Biotechnology Letters
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• v.47 no.4
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• pp.667-672
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• 2019

We compared two integration systems for stable expression of heterologous genes in Saccharomyces cerevisiae. A Candida glabrata-derived gene was used as the selective marker for the Cre/loxP system, and XYLP, XYLB, GRE3, and XYL2 genes were used as model heterologous genes and ligated into the universal pRS-CMT vector. The resulting pRS-XylP, pRS-XylB, pRS-Gre3, and pRS-Xyl2 plasmids were sequentially integrated into yeast chromosome VII by four integration processes (marker rescue and gene integration). The four introduced genes were successfully expressed. Further, the pRS-PBG2 plasmid harboring expression cassettes for the four genes was constructed for one-step integration. The four genes that were introduced were stably maintained as a gene cluster and were simultaneously expressed. The one-step integration was more effective for the simultaneous integration and expression of the four genes related to xylan/xylose metabolism. This method will enable the generation of a useful biosystem through appropriate use of gene integration methods.