• Korean Journal of Plant Resources
• /
• v.23 no.3
• /
• pp.248-255
• /
• 2010

We previously demonstrated that root colonization of the rhizobacterium, Pseudomonas chlororaphis O6, induced expression of a galactinol synthase gene (CsGolS1), and resulting galactinol conferred induced systemic resistance (ISR) against fungal and bacterial pathogens in cucumber leaves. To examine the role of galactinol on ISR, drought or high salt stress, we obtained T-DNA insertion Arabidopsis mutants at the AtGolS1 gene, an ortholog of the CsGolS1 gene. The T-DNA insertion mutant compromised resistance induced by the O6 colonization against Erwinia carotovora. Pharmaceutical application of 0.5 - 5 mM galactinol on roots was sufficient to elicit ISR in wild-type Arabidopsis against infection with E. carotovora. The involvement of jasmonic acid (JA) signaling on the ISR was validated to detect increased expression of the indicator gene PDF1.2. The T-DNA insertion mutant also compromised tolerance by increasing galactinol content in the O6-colonized plant against drought or high salt stresses. Taken together, our results indicate that primed expression of the galactinol synthase gene AtGolS1in the O6-colonized plants can play a critical role in the ISR against infection with E. carotovora, and in the tolerance to drought or high salt stresses.

• International Journal of Concrete Structures and Materials
• /
• v.2 no.2
• /
• pp.71-81
• /
• 2008

A macroscopic finite element model is applied to investigate the effect of fire induced spalling on the response of reinforced concrete (RC) beams. Spalling is accounted for in the model through pore pressure calculations in concrete. The principles of mechanics and thermodynamics are applied to compute the temperature induced pore pressure in the concrete structures as a function of fire exposure time. The computed pore pressure is checked against the temperature dependent tensile strength of concrete to determine the extent of spalling. Using the model, case studies are conducted to investigate the influence of concrete permeability, fire scenario and axial restraint on the fire induced spalling and also on the response of RC beams. Results from the analysis indicate that the fire induced spalling, fire scenario, and axial restraint have significant influence on the fire response of RC beams. It is also shown that concrete permeability has substantial effect on the fire induced spalling and thus on the fire response of concrete beams. The fire resistance of high strength concrete beams can be lower that that of normal strength concrete beams due to fire induced spalling resulting from low permeability in high strength concrete.

• 한국태양에너지학회:학술대회논문집
• /
• 2009.11a
• /
• pp.350-355
• /
• 2009

The crysralline silicon solar cell where the solar cell market grows rapidly is occupying of about 85% or more high efficiency and low cost endeavors many crystalline solar cells. The fabricaion process of high efficiency crystalline silicon solar cells necessitate complicated fabrication processes and Ti/Pd/AG contact, This metal contacts have only been used in limited areas in spite of their good srability and low contact resistance because of expensive materials and process. Commercial solar cells with screen-printed solar cells formed by using Ag paste suffer from loe fill factor and high contact resistance and low aspect ratio. Ni and Cu metal contacts have been formed by using electroless plating and light-induced electro plating techniques to replace the Ti/Pd/Ag and screen-printed Ag contacts. Copper and Silver can be plated by electro & light-induced plating method. Light-induced plating makes use the photovoltaic effect of solar cell to deposit the metal on the front contact. The cell is immersed into the electrolytic plating bath and irradiated at the front side by light source, which leads to a current density in the front side grid. Electroless plated Ni/ Electro&light-induced plated Cu/ Light-induced plated Ag contact solar cells result in an energy conversion efficiency of 16.446 % on 0.2~0.6${\Omega}$ cm, $20{\times}20mm^2$, CZ(Czochralski) wafer.

• Journal of Welding and Joining
• /
• v.23 no.3
• /
• pp.34-39
• /
• 2005

It is required for the steel materials used in the sour environment to have sufficient resistance to hydrogen induced cracking(HIC). For line pipe steels, HIC resistance could be varied during pipe making process due to the large plastic deformation applied in the thick-wall pipe. In order to figure out such effect, HIC tests were performed not only in the plate condition but in the pipe condition and their results were compared in terms of cracking ratio. Test results demonstrated a detrimental effect of plastic deformation to HIC resulting in a substantial increase in the cracking ratio after pipe forming process. All of the cracks found in the pipe material were located in the outer layer of pipe where the tensile strain was resulted during pipe forming stage. In order to understand the HIC resistance of the pipe but in the plate condition, it was suggested to pre-strain the plate to some extent before the HIC test.

• Animal cells and systems
• /
• v.7 no.3
• /
• pp.213-219
• /
• 2003

The response of plants to pathogens and wounding is dependent upon very sensitive perception mechanisms. Although genetic approaches have revealed a variety of resistance genes that activate common defense responses, defense-related proteins are not well characterized in plants. Therefore, we used a proteomic approach to determine which defense-related proteins are induced by salicylic acid (SA) and wounding in Chinese cabbage. We found that SA and wounding induce pathogenesis-related protein 1a (PR1a) at both protein and mRNA levels using proteomics and Northern blot analysis, respectively. This indicates that our proteomic approach is useful for identifying defense-related proteins. We also identified several other proteins that are induced by SA or wounding. Among the seven SA-induced proteins identified, four may be defense-related, including defense-related protein, phospholipase D (PLD), resistance protein RPS2 homolog, and L-ascorbate peroxidase. Out of the six wounding-induced proteins identified, three may be defense-related: heat shock cognate protein 70 (HSC70), polygalacturonase, and peroxidase P7. The precise functions of these proteins in plant defense responses await further study. However, identification of the defense-related proteins described in this study should allow us to better understand the mechanisms and signal transduction pathways involved in defense responses in Chinese cabbage.

• Journal of Ginseng Research
• /
• v.26 no.1
• /
• pp.1-5
• /
• 2002

It has been well known that Korea red ginseng has an antihypertensive effect. The antihypertensive effect may be due to its ability to change the peripheral resistance. Change of vascular tone in the resistance-sized artery contribute to the peripheral resistance, thereby regulate the blood pressure. Therefore, we investigated to clarify the vasorelaxing mechanism induced by crude saponin of Korea red ginseng in the resistance-sized mesenteric artery of rats. The resistance-sized mesenteric artery was isolated and cut into a ring. The ring segment was immersed in HEPES-buffered solution and its isometric tension was measured using myograph force-displacement transducer. Crude saponin of ginseng relaxed the mesenmetric arterial rings precontracted with norepinephrine (3$\mu$M) in dose-dependent manner (0.01 mg/㎖ -1 mg/㎖. The relaxation by crude saponin was smaller in endothelium-intact preparation than that in endothelium-denuded preparation. The contraction induced by A23187 or phorbol 12,13-dibutyrate was not affected by crude saponin of ginseng. The vasorelaxing effect of crude saponin of ginseng was significantly attenuated by the increase of the extracellular K$\^$+/ concentration. Crude saponin-induced vasorelaxation was not affected by tetraethylammonium (1 mM), glybenclamide (10$\mu$M), and 4-aminopyridine (0.1 mM) in these preparations. Ba$\^$2+/(10$\mu$M ∼100$\mu$M) markedly reduced the crude saponin-induced vasorelakation dose-dependently. From the above results, we suggest that crude saponin of ginseng may stimulate K$\^$+/ efflux and hyperpolarize the membrane, thereby cause the vasorelaxation in the resistance-sized mesenteric artery of rats.

• Biomedical Science Letters
• /
• v.11 no.2
• /
• pp.165-173
• /
• 2005

A potent demethylating agent, 5-Azacytidine (5-AzaC) has been widely used as in many studies on DNA methylation, regulation of gene expression, and cancer biology. The mechanisms of the demethylating activity were known to be formation of complex between DNA and DNA methyltransferase (MTase), which depletes cellular MTase activity. However, 5-AzaC can also induce hypermethylation of a transgene in a transgenic cell line, G12 cells and it was explained as a result of defense mechanisms to inactivate foreign gene(s) somehow. This finding evoked the question that whether the phenomenon of hypermethylation induced by 5-AzaC is limited to the transgene or it can be occurred in endogenous gene(s). In order to answer the question, mutagenicity test of 5-AzaC and molecular characterization of mutants obtained from the test were performed using an endogenous gene, thymidine kinase (tk) in Chinese hamster V79 cells. When V79 and V79-J3 subclone cells were treated with 1, 2.5 ,5, $10{\mu}M$ of 5-AzaC for 48 hours, their maximum mutant frequencies were revealed as $6\times10^{-3}\;at\;5{\mu}M$(350-fold induction over background) and $8\times10^{-3}\;at\;2.5{\mu}M$ (l,800-fold induction over background) respectively. Since the induction rates were too high to be induced by true mutations, many trifluorothymidine (TFT)-resistant $(TFT^R)$ cells were subjected to Northern blot analysis to check the presence of tk transcripts. Surprisingly, all clones tested possessed the transcripts in a similar level, that implicates the $TFT^R$ phenotype induced by 5-AzaC has not given rise to hypermethylation of the gene in spite of unusually high mutation frequency. In addition, it has shown that the TK activity in the pool of 5-AzaC-induced $TFT^R$ cells has about a half of that in spontaneously-induced $TFT^R$ cells or in non-selected parental V79-J3 cells. This result suggests that the mechanism(s) underlying the TFT-resistance between spontaneously occurred and 5-AzaC-induced cells may be different. These findings have shown that the $TFT^R$ phenotype induced by 5-AzaC has not given rise to hypermethylation of the tk gene, and 5-AzaC may be induced by one or combined pathways among many drug resistance mechanisms. The exact mechanisms for the 5-AzaC-induced $TFT^R$ phenotype remain to elucidate.

• Natural Product Sciences
• /
• v.18 no.4
• /
• pp.254-260
• /
• 2012

Adipose inflammation is linked to the development of insulin resistance and type 2 diabetes. Hesperidin (HES) is a flavonoid with antioxidant, anti-inflammatory and anti-diabetic properties. However, whether HES improves inflammation-mediated insulin resistance in adipose tissues remains unclear. The purpose of this study was to investigate whether HES attenuates inflammation-mediated insulin resistance in adipose tissue. Herein, RAW 264.7 cells and differentiated 3T3-L1 adipocytes were pretreated with various concentrations of HES in complete media for 1 h and then cultured in the presence or absence of LPS or TNF-${\alpha}$. Our results demonstrated that HES remarkably inhibited LPS-induced production of IL-6, TNF-${\alpha}$, and NO by RAW 264.7 cells in a dose-dependent manner. Also, HES inhibited TNF-${\alpha}$-induced production of IL-6 and $PGE_2$ in differentiated 3T3-L1 cells, while upregulated TNF-${\alpha}$-suppressed expression of adiponectin and PPAR-${\gamma}$ mRNA. These findings suggest that HES may ameliorate inflammation-mediated insulin resistance in adipose tissue.

• Natural Product Sciences
• /
• v.19 no.4
• /
• pp.316-323
• /
• 2013

Adipose tissue-derived chronic inflammation contributes to development of insulin resistance in obesity, leading to type 2 diabetes and cardiovascular disease. Baicalin, a flavonoid, has antioxidant, anti-inflammatory, antihyperglycemic, anti-adipogenic, and antiobesity effects. However, whether baicalin attenuates adipose tissue-derived development of insulin resistance remains still unclear. This study was to investigate effect of baicalin on the inflammatory changes involved in the development of insulin resistance in adipose tissue. RAW 264.7 cells and differentiated 3T3-L1 adipocytes were pretreated with various concentrations of baicalin in complete media for 1 h and then cultured in the presence or absence of LPS or TNF-${\alpha}$. Our results demonstrated that baicalin remarkably inhibited LPS-induced production of TNF-${\alpha}$, IL-6, and NO by RAW 264.7 cells in a dose-dependent manner. Baicalin also inhibited TNF-${\alpha}$-induced production of IL-6 and $PGE_2$ in differentiated 3T3-L1 cells in a dose-dependent manner, while upregulated TNF-${\alpha}$-suppressed expression of adiponectin and PPAR-${\gamma}$ mRNA and IRS-1 protein. These findings suggest that baicalin may prevent the adipose tissue-derived development of insulin resistance in obesity.

• Journal of Microbiology and Biotechnology
• /
• v.29 no.4
• /
• pp.571-576
• /
• 2019

Microenvironmental stress, which is naturally observed in solid tumors, has been implicated in anticancer drug resistance. This tumor-specific stress causes the degradation of topoisomerase $II{\alpha}$, rendering cells resistant to topoisomerase $II{\alpha}$-targeted anticancer agents. In addition, microenvironmental stress can induce the overexpression of 78kDa glucose regulated protein (GRP78), which can subsequently block the activation of apoptosis induced by treatment with anticancer agents. Therefore, inhibition of topoisomerase $II{\alpha}$ degradation and reduction in GRP78 expression may be effective strategies for inhibiting anticancer drug resistance. In this study, we investigated the active compound arctigenin, which inhibited microenvironmental stress-induced etoposide resistance in HT-29 cells. Arctigenin was also highly toxic to etoposide-resistant HT-29 cells, with an $IC_{50}$ value of $10{\mu}M$ for colony formation. We further showed that arctigenin inhibited the degradation of topoisomerase $II{\alpha}$ and reduced the expression of GRP78. Thus, these results suggest that arctigenin is a novel therapeutic agent that inhibits resistance to etoposide associated with microenvironmental stress conditions.