• Biomolecules & Therapeutics
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• v.26 no.3
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• pp.313-321
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• 2018

Anti-cancer drug resistance is a major problem in colorectal cancer (CRC) research. Although several studies have revealed the mechanism of cancer drug resistance, molecular targets for chemotherapeutic combinations remain elusive. To address this issue, we focused on the expression of cellular prion protein ($PrP^C$) in 5-FU-resistant CRC cells. In 5-FU-resistant CRC cells, $PrP^C$ expression is significantly increased, compared with that in normal CRC cells. In the presence of 5-FU, $PrP^C$ increased CRC cell survival and proliferation by maintaining the activation of the PI3K-Akt signaling pathway and the expression of cell cycle-associated proteins, including cyclin E, CDK2, cyclin D1, and CDK4. In addition, $PrP^C$ inhibited the activation of the stress-associated proteins p38, JNK, and p53. Moreover, after treatment of 5-FU-resistant CRC cells with 5-FU, silencing of $PrP^C$ triggered apoptosis via the activation of caspase-3. These results indicate that $PrP^C$ plays a key role in CRC drug resistance. The novel strategy of combining chemotherapy with $PrP^C$ targeting may yield efficacious treatments of colorectal cancer.

• Journal of the Korean Chemical Society
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• v.37 no.6
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• pp.618-625
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• 1993

Rate constants of hydrolysis of N-(benzoyl)-C-(N-methylanilino)imidoylchlorides were determined by UV spectrophotometry in 50% (v/v) aqueous methanol at 25$^{\circ}C$. On the basis of rate equation, substituent effect, solvent effect, salt effect, thermodynamic parameters and hydrolysis product analysis, it may be concluded that the hydrolysis of N-(benzoyl)-C-(N-methylanilino)imidoylchlorides proceed through $S_N$1 mechanism via azocarbonium ion intermediate in the range of from pH 3.0 to pH 10.0, while above pH 10.0 and below pH 3.0 the hydrolysis proceeds through nucleophilic addition-elimination (A$d_{N-E}$) mechanism.

• Tribology and Lubricants
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• v.19 no.5
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• pp.274-279
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• 2003

$Al-SiC_{p}$ composite layer was prepared by plasma thermal spray on aluminum substrate. The homogeneously dispersed composite powder for thermal spray was fabricated by mechanical alloying with ball mill. The friction tests of the composite layers and commercial aluminum alloys for comparison were performed in the temperature range of 20∼$260^{\circ}C$ with the interval of $40^{\circ}C$ with steel counter-face. Friction coefficient was recorded during test sequence, and the microstructure of surface and debris was investigated by optical and scanning electron microscope. Friction coefficients of composite and aluminum alloys at room temperature were similar except pure aluminum. As the temperature increase, friction coefficient was increased rapidly in AC4C, AC2A. But friction coefficient of $Al-SiC_{p}$ composite was not increased so much up to $220^{\circ}C$. Consequently, the reinforcement of $SiC_{p}$ into aluminum matrix increased the stability of friction coefficient as well as wear resistance.

• Journal of the Korean Society of Safety
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• v.10 no.4
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• pp.81-86
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• 1995

In order to apply to analysis methods of mechanism and cross tabulation methods for the influence factors by the accident types to the object of accidents which occurred in R.C and P.C methods among the accidents in construction work sites, the latent hazards in P.C method are evaluated from the data of accidents in H Company from Jan. 1, 1993 to Dec. 31, 1993. The relationship between accident types and unsafe acts, unsafe conditions are recognized and the hazards of R.C method and P.C method are compared from the data acquired by the analysis of causes for a kind of occurrence mechanism. In conclusions, the items such as causes of accidents, accidents types, occurrence time, and the characteristics, are concentrated on one side in the P.C method, which is quite different from R.C method. Therefore the control method for the accident causes is easily established with a lot of effective advantages. The frequency and severity of accidents in P.C method are so low in comparison with R.C method.

• Preventive Nutrition and Food Science
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• v.2 no.4
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• pp.333-337
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• 1997

Trans-cinnamic acid-4-hydroxylase(tC4H) is the first cytochrome P450-dependent monooxygenase of the phenylpropanoid pathway. The roots of avocado seedlings were wounded and examined to determine whether the tC4H would be activated in response to wounding and/or whether tC4H activity be modulated by the application of exogenous p-coumarate. At the specified length of times, the wounded and treated roots were either frozen in liquid nitrogen or used immediately to extract microsomal proteins. The microsomal proteins were subjected to immunoblot analysis using polyclonal antibodies against CYP73 of tC4H gene. In this study, tC4H was induced in wounded roots sealed in bags within 6 hours, and in low level({TEX}$10^{-8}${/TEX}M) of p-coumarate solution within 24 hours, whereas the olution without p-coumarate and high levels of p-coumarate solution repressed tC4H induction in wounded roots. These results indicate that tC4H is induced by wounding in the root of avocado, and is inhibited by the application of exogenous p-coumarate.

• Bulletin of the Korean Chemical Society
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• v.31 no.12
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• pp.3745-3748
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• 2010

Pd(II) p-tolylamide Pd(2,6-$(Ph_2PCH_2)_2C_6H_3$)(NH($C_6H_4Me$-p)) (1) was metathetically prepared by the reaction of Pd(2,6-$(Ph_2PCH_2)_2C_6H_3$)Cl with NaNH($C_6H_4Me$-p). Treatment of 1 with carbon dioxide affords the palladium(II) carbamate Pd(2,6-$(Ph_2PCH_2)_2C_6H_3$)(OC(O)NH($C_6H_4Me$-p)) (2), quantitatively. Complex 2 reacts with HX (X = Cl, OTf) to give Pd(2,6-$(Ph_2PCH_2)_2C_6H_3$)X, $NH_2$(p-Tol) and $CO_2$. Reaction of the palladium(II) carbamate with MeI produced Pd(2,6-$(Ph_2PCH_2)_2C_6H_3$)I along with generation of methyl N-tolylcarbamate MeOC(O)NH($C_6H_4Me$-p), exclusively.

• Journal of Microbiology and Biotechnology
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• v.27 no.9
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• pp.1586-1592
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• 2017

Some promoters were isolated and characterized from the genome of Leuconostoc mesenteroides SY2, an isolate from kimchi, a Korean traditional fermented vegetable. Chromosomal DNA of L. mesenteroides SY2 was digested with Sau3AI and ligated with BamHI-cut pBV5030, a promoter screening vector containing a promoterless cat-86. Among E. coli transformants (TFs) resistant against Cm (chloramphenicol), 17 were able to grow in the presence of $1,000{\mu}g/ml$ Cm and their inserts were sequenced. Transcription start sites were examined for three putative promoters (P04C, P25C, and P33C) by primer extension. Four putative promoters were inserted upstream of a promoterless ${\alpha}$-amylase reporter gene in $pJY15{\alpha}$. ${\alpha}$-Amylase activities of E. coli TFs containing $pJY15{\alpha}$ (control, no promoter), $pJY03{\alpha}$ ($pJY15{\alpha}$ with P03C), $pJY04{\alpha}$ (with P04C), $pJY25{\alpha}$ (with P25C), and $pJY33{\alpha}$ (with P33C) were 66.9, 78.7, 122.1, 70.8, and 99.3 U, respectively. Cells harboring $pJY04{\alpha}$ showed 1.8 times higher activity than the control. Some promoters characterized in this study might be useful for construction of food-grade expression vectors for Leuconostoc sp. and related lactic acid bacteria.

• Microbiology and Biotechnology Letters
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• v.26 no.4
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• pp.275-282
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• 1998

To investigate the increased acid tolerance of a acid-resistant mutant Leuconostoc paramesenteroides P-100 improved as a kimchi starter, proton permeability, ATPase acitivity, glycolysis activity, $Mg^2$sup +/ releasement, and membrane fatty acid composition were studied and comprised with its wild type Leuconostoc paramesenteroides Pw. In the proton permeability experiment, the maximum values of the average half time (t$\_$1/2/) of pH equilibration through the cell membrane of the Pw and the P-100 were about 6.4 min and 7.8 min in 150 mM KCI solution, respectively. In the 3% NaCl solution, the t$\_$1/2/ values of the Pw and the P-100 were 5.5 min and 6.9 min, respectively. The values and pHs of maximal specific activities of ATPase originated from the Pw and the P-100 were 0.5 unit/mg protein and 0.78 unit/mg protein at pH 6.0, respectively. The result of pH dependence of glycolysis showed that the P-100 had higher activities than that of Pw except at pH 7.0. The releases of magnesium from the Pw and the P-100 were observed about 54.5% and 23.2% at pH 4.0 after 2 hours, respectively. The results of comparison of membrane fatty acid composition of the Pw with the P-100 showed that C$\_$8:0/, C$\_$9:0/, C$\_$10:0/, C$\_$11:0/, C$\_$18:0/, and C$\_$19:0,cyclo/ were major different fatty acids between two strains and the content of C$\_$18:1/, and C$\_$19:0,cyclo/ were 2.8%, N.D (not detected) in the Pw and 0.4%, 2.3% in the P-100. These results indicated that acid tolerance of the P-100 was significantly improved in comparison with its wild type Pw.

• Journal of Animal Science and Technology
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• v.48 no.4
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• pp.521-532
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• 2006

An in vitro study was conducted to examine the effect of addition level of carbohydrates on fermentation characteristics, and bio-hydrogenation of unsaturated fatty acids by mixed rumen bacteria when incubated with soybean oil or flaxseed oil. Four levels(0%, 0.3%, 0.6% and 0.9%, w/v) of the mixed carbohydrates(glucose, cellobiose, soluble starch, 1:1:1, in weight basis) and oil sources(soybean or flaxseed oil, 60mg in 150ml culture solution) were added to the mixed solution of strained rumen fluid with artificial saliva(1:4, v/v), and incubated anaerobically for 12 hours at 39℃. pH and ammonia-N concentration were lower by increasing the substrate levels at all incubation periods(P<0.05～P<0.001). The propionate proportion increased(P<0.001), but acetic acid and butyric acid decreased(P<0.001) with the substrate level at 6 and 12 h incubations. Oil sources did not influence the proportions of individual VFA. At the end of incubation, the proportions of C18:0(P<0.01), C18:1(P<0.001) and trans-11C-18:1(P<0.01) were reduced but those of C18:2(P<0.001) and C18:3(P<0.01) were enhanced by the addition of flaxseed oil compared to addition of soybean oil. The proportions of C18:0 and total CLA were reduced(P<0.01) but those of trans-11-C18: (P<0.05) and C18:2(P<0.01) were increased with the substrate level when incubated with soybean oil or flaxseed oil. There were interactions(P<0.05) in the proportions of C18:1, C18:2 and C18:3(P<0.01) between oil source and substrate level. The proportions of cis-9, trans-11-CLA and trans-10, cis-12-CLA tended to reduce with substrate level, although there was no significant difference between treatments.

• Microbiology and Biotechnology Letters
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• v.32 no.3
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• pp.212-217
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• 2004

The gene coding for mannanase from Bacillus subtilis WL-7, a number of glycosyl hydrolase family 26, was hyperexpressed in Escherichia coli. Two recombinant plasmids, pE7MAN and pENS7, were constructed by introducing the complete mannanase gene and the mature mannanase gene lacking N-terminal signal peptide region into a expression vector pET24a(＋), respectively. The level of mannanase produced by E. coli BL21 (DE3) carrying pENS7, which included the mature mannanase gene, was considerably higher than that by E. coli BL21 (DE3)/pE7MAN. Almost mannanase produced by the recombinant E. coli carrying pENS7 at growth temperature of $37^{\circ}C$ existed as inactive enzyme of insoluble form. Growth at temperature below $31^{\circ}C$ increased the soluble fraction of mannanase having catalytic activity in the recombinant E. coli cells. The highest productivity of active mannanase was observed in cell-free extract of the recombinant E. coli grown at growth temperature ranging from $25^{\circ}C$ to $28^{\circ}C$, while mannanase activity per soluble protein of the cell-free extract was highest in the cells grown at $^31{\circ}C$.