• Journal of Microbiology and Biotechnology
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• v.10 no.2
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• pp.137-142
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• 2000

Environmental stres is known to induce heat shock proteins (HSPs) in eukaryotic cells. However, the induction of HSPs in host cells by microbial infection has not yet been well explained. Staphylococcus aureus (S. aureus) is one of the major pathogens in the pathogenesis of endovascular diseases such as infective endocarditis. In this study, the synthesis of stress-inducible 70 kDa HSP was investigated in the endothelial cells (ECs) after 3 h to 20 h of incubation with S. aureus. The dffect of S. aureus infection on the expression of HSP70 in cultured ECs was analyzed using laser scanning confocal microscopy (LSCM). The increase of HSP70 expression in ECs infected by S. aureus ($10^4{\;}cfu/ml$) for 20 h was 1.1-fold higher than that in heat shock treated ECs and 2.2-fold higher than that in untreated cells. Heat shock is known to induce intranucleus HSP70 expression in mammalian cells, whereas the S. aureus infection induced perinuclear expression in ECs as observed by LSCM. Consequently, the expression of HSP70 in ECs plays an important role in the pathogenesis of endovascular infection.

• Metals and materials international
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• v.24 no.6
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• pp.1327-1332
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• 2018

In this study, a novel approach to the explosive synthesis of titanium carbide (TiC) is discussed. Nonstoichiometric $TiC_x$ powder was produced via the underwater explosion of a Ti powder encapsulated within a spherical explosive charge. The explosion process, bubble formation, and synthesis process were visualized using high-speed camera imaging. It was concluded that synthesis occurred within the detonation gas during the first expansion/contraction cycle of the bubble, which was accompanied by a strong emission of light. The recovered powders were studied using scanning electron microscopy and X-ray diffraction. Submicron particles were generated during the explosion. An increase in the carbon content of the starting powder resulted in an increase in the carbon content of the final product. No oxide byproducts were observed within the recovered powders.

• YAKHAK HOEJI
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• v.45 no.1
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• pp.16-22
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• 2001

Novel yakuchinone derivatives have been designed, synthesized and evaluated their inhibitory activity of NO production in lipopolysaccharide (LPS)-activated macrophages. From this study, some enone compounds have been found to be highly active in the assay. In view of the importance of NO in septic shock and inflammation, these compounds may be useful candidates for the development of new drug to treat endotoxemia and inflammation accompanying overproduction of NO.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.273.1-273.1
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• 2002

Temperature change is one of the major environmental factors to influence human skin. However. the relationship between temperature and melanogenesis has received little attention. In the present study. we investigated the effects of temperature change including heat shock on melanogenesis using a mouse melanocyte cell line, Mel-Ab. Our results demonstrated that cells maintained at 37$^{\circ}C$ showed maximal melanin synthesis. (omitted)

• Journal of Powder Materials
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• v.8 no.3
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• pp.174-178
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• 2001

The microstructure and mechanical properties of $Si_3N_4/BN $nanocomposites synthesized by chemical processing were investigated. The nanocomposites containing 15 vol% hexagonal BN (h-BN) were fabricated by hot-pressing $\alpha-Si_3N_4$powders covered with turbostratic BN (t-BN). The t-BN coating on $\alpha-Si_3N_4$particles was prepared by heating $\alpha-Si_3N_4$ particles covered with a mixture of boric acid and urea in hydrogen gas. TEM observations of this nanocomposite revealed that nano-sized h-BN particles were homogeneously dispersed within $Si_3N_4$grains as well as at grain boundaries. The strength and thermal shock resistance were significantly improved in comparison with the $Si_3N_4/BN$ microcomposites.

• Journal of Microbiology
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• v.33 no.4
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• pp.322-327
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• 1995

Tolerance of Mycobacterium sp. against organic solvents has been induced for the cholesterol side chain degradation by adding chemicals associated with synthesis of fatty acids or alcohols. Biotin of 300 .mu.g/1 and 0.5% aqueous ethanol solution were optima for the enhancement of ethanol tolerance of the microorganism. The induction of ethanol tolerance by biotin was found to be due to increase of degree of unsaturation of the fatty acids in membranous phospholipid of the cell, especially due to increase of oleic acid content. However when 0.5% of ethanol was added for the ethanol tolerance induction, there was an ambiguous correlation between ethanol tolerance and degree of unsaturation of the fatty acids, in spite of the fact that the induction increased the content of unsaturated fatty acids. Addition of 0.5% of ethanol induced several ethanol shock proteins having molecular weight similar to that of heat shock proteins.

• Journal of Microbiology
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• v.39 no.3
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• pp.162-167
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• 2001

Methylovorus sp. strain SS1 DSM 11726 was found to grow continuously when it was transferred from 30$\^{C}$ to 40$\^{C}$ and 43$\^{C}$. A shift in growth temperature from 30$\^{C}$ to 45$\^{C}$, 47$\^{C}$ and 50$\^{C}$ reduced the viability of the cell population by more than 10$^2$, 10$^3$and 10$\^$5/ folds, respectively, after 1h cultivation. Cells transferred to 47$\^{C}$ and 50$\^{C}$ after preincubation for 15 min at 43$\^{C}$, however, exhibited 10-fold increase in viability. It was found that incubation for 15 min at 40$\^{C}$ of Methylovorus sp. strain SSl grown at 30$\^{C}$ was sufficient to accelerate the synthesis of a specific subset of proteins. The major heat shock proteins had apparent molecular masses of 90, 70, 66, 60, and 58 kDA. The 60 and 58 kDa proteins were found to cross-react with the antiserum raised against GroEL protein. The heat shock response persisted for over 1h. The shock proteins were stable for 90 min in the cell. Exposure of the cells to methanol induced proteins identical to the heat shock proteins. Addition of ethanol induced a unique protein with a molecular mass of about 40 kDa in addition to the heat-induced proteins. The proteins induced in paraquat-treated cells were different from the heat shock proteins, except the 70 and 60 kDa proteins.

• Molecules and Cells
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• v.23 no.2
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• pp.239-245
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• 2007

DnaK is a major antigen in Streptococcus pneumoniae, and is induced by a minor shift in temperature (30 to $37^{\circ}C$) but not by ethanol shock. Although HrcA in the presence of $Ca^{{+}{+}}$ represses the expression of both groEL and hrcA, the control of transcription of the dnaK operon is not completely understood. In this study, the dnaK operon of S. pneumoniae (5' hrcA-grpE-dnaK-dnaJ) was cloned and analyzed. It contains large intergenic regions in grpE/dnaK and dnaK/dnaJ. Pulse labeling with [$^{35}S$]-methionine and immunoblot analyses revealed the presence of higher levels of DnaK than of HrcA even in the presence of $Ca^{{+}{+}}$ after heat shock suggesting that $Ca^{{+}{+}}$ differentially regulates the heat shock responses of hrcA and dnaK. By blocking de novo mRNA synthesis with rifampin it was shown that neither the hrcA nor the groEL transcripts were stabilized by heat shock even though dnaK transcripts were stabilized. We conclude that S. pneumoniae uses fine regulation of the transcription of the individual genes of the tetracistronic dnaK operon to cope with the various stresses experienced during infections.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.669-670
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• 2009

• Journal of Aquaculture
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• v.13 no.2
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• pp.181-186
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• 2000

Relationship between hsp 70 expression and development of thermotolerance in the olive flounder was investigated by exposing the fish to 23 or 26$^{\circ}C$ for 1 h. After selected intervals, they were re-exposed to 31$^{\circ}C$ for a duration of 15 min. Theremotolerance rapidly developed with increasing interval and peaked at 3 h interval. Subsequently, it gradually decayed and disappeared by 24 h interval. The flounder displayed remarkably high levels of hsp 70 mRNA and protein, as compared to control flounder. Hence, the olive flounder acquires thermotolerance, which is positively correlated with the synthesis of hsp 70.