• YAKHAK HOEJI
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• v.58 no.1
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• pp.7-11
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• 2014

To study the resistance mechanism of E. faecalis to LCB01-0371, several resistant mutants to LCB01-0371 or linezolid were isolated by step-wise selection. The frequency of spontaneous mutations resistant to LCB01-0371 was lower than that of linezolid in E. faecalis. The genetic variations in resistant mutants were analyzed by DNA sequencing of domain V of 23S rRNA in each mutant. The first-step mutant to LCB01-0371 had a G2576T point mutation in V domain of 23S rRNA. However, no resistant mutant to LCB01-0371 was isolated in second-step mutant selection.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.3
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• pp.163-172
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• 2014

The purpose of earthquake resistant design for typical bridges is the No Collapse Design and the Earthquake Resistant Design Part of Roadway Bridge Design Code provides a design process to construct the Ductile Failure Mechanism for the bridge structure. However, if it is not practical to provide the Ductile Failure Mechanism due to structure types or site conditions, the Brittle Failure Mechanism is an alternative way to get the No Collapse Design. As well as the existing design process constructing the Ductile Failure Mechanism, the Earthquake Resistant Design Part provides a ductility-based design process as an appendix, which is prepared for bridges with reinforced concrete piers. According to the new design process, designer determines a required response modification factor for substructure and transverse reinforcement for confinement therefrom. In this study, a typical bridge with steel bearing connections and reinforced concrete piers is selected for which the existing as well as the ductility-based design processes are applied and different results from the two design processes are identified. Based on the results, an earthquake resistant design procedure is proposed in which designers should consider the two design processes.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.2
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• pp.187-192
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• 2016

While structures are designed within elastic range by other designs, plastic behavior of structures should be verified and controlled in order to prevent structural collapse by the earthquake resistant design. No Collapse Requirement for typical bridges is to avoid falling down of superstructure by way of plastic behavior of certain structural elements and to operate emergency vehicles after earthquake. Such plastic behavior is restricted to connections or pier columns and appropriate measures are required for each case. Earthquake Resistant Design part of Roadway Bridge Design Code provides design processes for Ductile Collapse Mechanism by forming plastic hinges at pier columns. Also for bridges with reinforced concrete piers ductility-based design processes are provided as an appendix constructing Brittle Collapse Mechanism with connection yielding. In this study, a typical bridge with steel bearing connections and reinforced concrete piers is selected and No Collapse Design procedure considering both Ductile and Brittle Collapse Mechanism is proposed together with revisions required for the Earthquake Resistant Design part.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.3
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• pp.283-288
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• 2011

For the earthquake resistance design designer should provide that structural yielding process is principally designed with the ductile failure mechanism. In order to get the ductile failure mechanism for typical bridges, pier columns yielding should occur before that of connections. However domestic bridge design with unnecessary stiff substructure leads to unnecessary seismic loads and makes it difficult to get the ductile failure mechanism. Such a problem arises from the situation that earthquake resistant design is not carried out in the preliminary design step. In this study a typical bridge is selected as an analysis bridge and design strengths for connections and pier columns are determined in the preliminary design step by carrying out earthquake resistant design. It is shown through this procedure that it is possible to get the ductile failure mechanism with structural members determined by other design.

• Structural Engineering and Mechanics
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• v.1 no.1
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• pp.31-46
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• 1993

The motivations of the application of shakedown analysis to the earthquake-resistant design of ductile moment-resisting steel structures are presented. The problems which must be solved with this application are also addressed. The illustrative results from a series of static and time history nonlinear analyses of one-bay three-story steel frame and the related discussions have shown that the incremental collapse may be the critical design criterion in case of earthquake loading. Based on the findings, it was concluded that the inelastic excursion mechanism for alternation load pattern, such as in earthquake, should be the sidesway mechanism of the whole structure for the efficient mobilization of the structural energy dissipating capacity and that the shakedown analysis technique can be used as a tool to ensure this mechanism.

• KSBB Journal
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• v.13 no.4
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• pp.383-390
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• 1998

Bacillus subtilis DT134 was resistant to 50-fold higher concentration of cadmium ions (Cd2+) than cadmium-sensitive B. subtilis BD224 in Luria Broth (LB) medium. Minimal inhibition concentration test in LB agar plates also showed similar results. The elevated cadmium resistance of B. subtilis DT134 strongly suggested a possible existence of cadmium resistance gene in it. Southern blot with Staphylococcus aureus cadA gene fragment (757 bp NlaIV-XmnI cadA DNA fragment) as probe was carried out to test the existence and similarity of the gene. In high stringency condition, there was no detectable signal, but in low stringency, a strong signal specific to the cadA probe could be detected. These results strongly suggested that there was some similarity between total DNA of B. subtilis DT134 and S. aureus pl258 in terms of cadmium resistance gene and the resistance mechanism might be an efflux mechanism. The subsequent efflux experiment showed that the cadmium resistance mechanism of B. subtilis DT134 was also due to the efflux of cadmium.

• The Korean Journal of Pesticide Science
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• v.9 no.1
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• pp.88-96
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• 2005

Paraquat-resistant biotype of Conyza canadensis (L.) Cronq. was determined by chlorophyll loss and random amplified polymorphic DNA (RAPD) analysis and the resistant mechanism was investigated with respect to absorption, translocation, and binding constant. RAPD analysis for paraquat resistant (R) and susceptible (S) biotypes found in a pear orchard revealed that the biotypes possessed remote genetic relationship. Chlorophyll loss, as an indication of paraquat toxicity, of S biotype was 7.8-fold greater than that of R biotype. There were no differences in contents of epicuticular wax and cuticle and amounts of [14C]paraquat penetrating the cuticle between the two biotypes. Little translocation of the herbicide out of the treated leaf was observed in either biotype. Binding constants of paraquat to the cell wall and thylakoid membrane were 7.4-fold and 16.9-fold, respectively, higher in R biotype than in S biotype. The results suggest that the resistance mechanism of C. canadensis biotype is due partly to high binding affinity of paraquat to the cell wall and thylakoid membrane.

• Journal of the Korean Society of Tobacco Science
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• v.19 no.2
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• pp.117-123
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• 1997

Viral coat protein (CP) encoding cDNA with artificial start and stop codons was synthesized by reverse-transcriptase polymerase chain reaction (RT-PCR) from the Korean isolate of potato virus Y-vein nectrosis strain (pVY-VN). To make PVY CP cDNA to untranslatable form, three stop codons were inserted near the start codon by "megaprimer-PCR" method. The untranslatable CP cDNA was subcloned to plant expression vector and transferred to N. tabacum cv. NC82 by Agrobacterium-mediated transformation. Highly resistant plants to PVY infection were screened, based on symptom development after mechanical virus inoculation. By genomic PCR and Southern blot analysis, one or more copies of the untranslatable CP gene were found in all transformants. From northern blot analysis, highly resistant transgenic lines had very low level of CP transcript but susceptible lines had high level, suggesting resistance to PVY infection should be related to RNA-mediated mechanism.mechanism.

• Journal of Integrative Natural Science
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• v.5 no.2
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• pp.72-78
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• 2012

Multidrug resistance is a major obstacle in cancer chemotherapy. Cancer cells efflux chemotherapeutic drug out of cell by means of transporter and reduce the active concentration of it inside cell. Such transporters are member of the ATP binding cassettes (ABC) protein. It includes P-gp, multiple resistant protein (MRP), and breast cancer resistant protein (BCRP). These proteins are widely distributed in the human cells such as kidney, lung, endothelial cells of blood brain barrier etc. However, there are number of drugs developed for it, but most of them are getting transported by it. So, still there is necessity of a good modulator, which could effectively combat the transport of chemotherapeutic agents. Natural products origin modulators were found to be effective against transporter such as flavonoids, which belongs to third generation modulators. They have advantage over synthetic inhibitor in the sense that they have simple structure and abundant in nature. This review focuses on the P-gp structure its architecture, efflux mechanism, herbal inhibitors and their mechanism of action.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.4
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• pp.328-334
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• 2002

A Lindernia dubia (L.) Pennell var. dubia accession from Jeonnam province, Korea was tested for resistance to sulfonylurea (SU) herbicides, imazosulfuron and pyrazosulfuron-ethyl in whole-plant response bioassay. The accession was confirmed resistant to both herbicides. The $GR_{50}$ (herbicide concentration that reduced shoot dry weight by 50%) values of resistant accession were 264 and 19 times higher to imazosulfuron and pyrazosulfuronethyl, respectively, than that of the standard susceptible accession. The surviving resistant L. dubia after pyrazosulfuron-ethyl + molinate application can be controlled by sequential applications of soil-applied herbicides, butachlor, dithiopyr, pyrazolate, and thiobencarb and foliar herbicides, bentazon. Sulfonylurea-based mixtures such as mixtures of azimsulfuron + anilofos, bensulfuron-methyl + oxadiazon, pyrazosulfuron-ethyl + fentrazamide, and pyrazosulfuron-ethyl + anilofos + carfentrazon can also be used to control the surviving resistant L. dubia. However, use of these mixtures should be restricted to a special need basis. Thus, we suggest that sequential applications of non-SU-based mixtures such as butachlor + pyrazolate and MCPB + molinate + simetryne be used to control the surviving resistant L. dubia after SU herbicide applications. Rice yield was reduced 24 % by resistant L. dubia that survived after the pyrazosulfuron-ethyl + molinate application compared with pyrazolate + butachlor in transplanted rice culture. In vitro ALS activity of the resistant biotype was 40 and 30 times more resistant to imazosulfuron and pyrazosulfuron-ethyl, respectively, than the susceptible biotype. Result of in vitro ALS assay that the resistance mechanism of L. dubia to SU herbicides may be due, in part, to an alteration in the target enzyme, ALS.