• Journal of Life Science
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• v.20 no.3
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• pp.416-423
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• 2010

In this study, the properties and gene expression of the lactate dehydrogenase (EC 1.1.1.27, LDH) isozyme were studied in angelfish (Pterophyllum scalare) - known for their adaptation to the low oxygen environment of the tropics - which were acclimated to acute temperature change ($27{\pm}0.5{\rightarrow}18{\pm}0.5^{\circ}C$) and dissolved oxygen (DO) change ($6{\pm}1{\rightarrow}18\;ppm$) for 2 hours. The properties of the LDH isozymes were confirmed in the native-polyacrylamide gel electrophoresis, Western blot analysis and enzyme activity measurement. Liver- and eye-specific Ldh-C gene were expressed in liver, eye and brain tissues. Through Western blot analysis, the LDH $A_4$ isozyme was shown to have a more cathodal mobility relative to the $B_4$ isozyme. In the liver tissue, the LDH $A_4$ isozyme increased with temperature drop while the $B_4$ isozyme decreased. The LDH $A_4$ and $C_4$ isozymes increased with DO increment, while the $B_4$ isozyme decreased. In the eye tissue, the LDH $A_4$ and B4 isozymse increased with temperature drop while the $B_4$ isozyme decreased. The LDH $A_4$ and $B_4$ isozymes increased with DO increment, but the $C_4$ isozyme and isozymes including the subunit C decreased. In the heart tissue, LDH activity increased with DO increment, as well as the LDH $B_4$ isozyme. In the brain tissue, the LDH $A_4$ and $B_4$ isozymes increased with temperature drop. The LDH $B_4$ isozyme increased with DO increment. Accordingly, since the liver- and eye-specific Ldh-C are influenced by changes in DO and the LDH $B_4$ and $C_4$ isozymes are relatively controlled in the liver and eye tissues, the $C_4$ isozyme can be considered to have a lactate oxidase function.

• Journal of Yeungnam Medical Science
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• v.13 no.2
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• pp.159-172
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• 1996

대기오염물질이면서 동시에 생체내 화학반응의 산물이기도 한 nitric oxide(NO)는 그 생체내 분포가 광범위하고 생리적 역할이 다양하여, 최근의 생명과학 분야에서 가장 크게 주목받는 몇가지 연구대상 중 하나이다. 세포에서의 NO 산생은 nitric oxide synthase (NOS)에 의해 촉매되는데, 이들은 brain form (bNOS, neuronal; nNOS, NOS I), inducible form (iNOS), 및 endothelial form(eNOS)로 구분되는데, 이중 bNOS(nNOS)와 eNOS는 inducible form에 대비되는 constitutive form(cNOS)에 해당하므로 각각 ncNOS 와 ecNOS로도 불리운다. NOS는 아미노산인 L-arginine을 산소와 결합시켜 L-citrulline으로 변환시키면서 NO를 유리하고, 이 NO는 세포내의 guanylate cyclase를 활성화하여 cyclic GMP를 생산하거나, superoxide(O2-) 및 수소이온과 차례로 결합하여 반응성이 매우 높은 수산화기(-OH)를 발생시켜 세포독작용을 유발하기도 한다. 정상상태에서 뇌혈관내피세포의 ecNOS로 부터 유리된 NO는 혈관을 확장시켜 신경세포에 대한 산소공급을 원활히 유지해 주지만, 순환장애를 일으켰을 때는 뇌조직내의 iNOS로부터 대량의 NO가 유출되어 신경세포의 손상을 가져온다. 호흡기에서는 NO가 기도평활근을 이완시키고 폐혈류를 개선하므로, 미숙아나 성인의 호흡장애시에 소량의 NO를 흡입시키면 oxygenation을 호전시킬 수 있다. 그러나 대기오염이나 흡연 등으로 대량의 NO를 흡입할 경우 치명적인 폐부종이나 methemoglobin혈종을 일으킬 수 있다. 순환계에서는 cNOS가 혈관을 확장시켜 조직의 혈류를 유지하는데 일익을 담당한다. 세균내 독소(lipopolysaccharide; LPS)나 각종 명역조절물질들이 혈관내피세포와 혈관평활근세포로 부터 과다한 NO를 유리시키면 혈압이 급격히 떨어져 순환허탈상태에 빠지게 된다. 심장에서는 관상혈관 내피세포의 eNOS가 심근의 혈류를 유지해 주지만 허혈이나 세균내독소 또는 면역조절물질 등에 의하여 심근세포나 침윤된 대식세포의 iNOS로 부터 과량의 NO가 유리되면 심근세포의 손상이 초래된다. 신장에서는 내피세포의 cNOS에 의하여 사구체여과가 조절되고 있는데, 세균내독소나 면역 조절물질 등에 의하여 사구체관막세포(mesangial cell)등의 iNOS로 부터 과량의 NO가 유리되면 신조직과 사구체의 손상을 초래한다. 위와 같이 대부분의 장기에서 ecNOS는 조직의 혈류를 유지하는 역할을 하며, iNOS는 애초 세균 등 침입자에 대한 세포독작용이 그 존재 목적이라고 풀이할 수 있겠으나 일종의 부작용으로 자체조직의 손상을 초래하게 되는 것으로 본다. 따라서 NO와 관련된 각종 병변의 치료를 위해서는 NOS의 비선택성 억제제인 arginine 유도체 보다는 iNOS에 대한 선택적 억제제인 S-methylisothiourea(SMT), aminoethylisothiourea(AETU), aminoguanidine (AMG), agmatine, L-canavanine, transforming growth factor b1(TGF-b1) 등의 사용을 검토해 보는 것이 타당할 것으로 사료된다.

• Journal of Life Science
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• v.14 no.2
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• pp.315-319
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• 2004

For antibody development of human serine palmitoyltransferase (SPT, EC 2.3.1.50), SPTLC1 and SPTLC2 genes were subcloned in pRset vector and expressed in E. coli BL21 (DE3)pLys cells. Eucaryotic SPT is a membrane-bound heterodimer enzyme, while all other members are soluble homodimer enzymes. cDNA library were obtained from total RNA from human embryo kidney cell line, HEK293, using RT-PCR and PCR with specific primers was carried out for preparing SPTLC1 and SPTLC2 genes. pRset vector which can express hexahistidine-tag fusion protein was used and the DNA sequences of pRsetB/SPTLC1 and pRsetA/SPTLC2 were confirmed. Recombinant BL21 cells with SPTLC subunits were selected with LB plate containing ampicillin and chroramphenicol. SPTLC1 and SPTLC2 proteins were induced with 1 mM IPTG and seperated on 10% SDS-PAGE gel. Expressed proteins were confirmed by western blotting with His-tag antibody.

• Korean Journal of Agricultural Science
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• v.49 no.1
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• pp.1-10
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• 2022

One hundred and twenty imprinting control region (ICR) mouse with initial body weights of 26 ± 2 g (5 weeks old) were assigned to six treatments for a two-week feeding trial to determine the effect of Pediococcus pentosaceus strains (PpS) which were isolated from three different types of Kimchi in ICR mice infected with Escherichia coli (Ec) or Salmonella Typhimurium (ST). Six groups constituted a normal control group without Ec or ST orally administrated (NC-; n = 20), a normal control group (NC+; n = 20), a group for which Lactobacillus plantarum was orally administrated (LP; n = 20), a group for which PpS A was orally administrated (PSA; n = 20), a group for which PpS B was orally administrated (PSB; n = 20), and a group for which PpS C was orally administrated (PSC; n = 20), the latter five groups constituted the Ec infected groups and the ST infected groups of 10 mice each. LP and PSC showed significantly (p < 0.05) improved growth performance compared to the other groups, except for NC- in the Ec infected mice group. NC+ showed significantly lower (p < 0.05) growth performance compared to the other groups, except for NC- in the ST infected mice groups. Regarding the Ec and Salmonella counts in the intestine, the LP and PSC groups had significantly lower (p < 0.05) counts than the NC+ and PSB groups. In conclusion, LP and PSC strains isolated from Kimchi can act as probiotics by inhibiting Ec and ST.

• Korean Journal of Microbiology
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• v.33 no.4
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• pp.237-241
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• 1997

Lipase (EC 3.1.1.3) in the culture filtrate of Streptomyces coelicolor A3(2) was active on ${\alpha}$-naphthyl-butyrate as well as on various triacylglycerols with different lengths of acyl chains. The extracellular lipase was purified 15-fold by ammonium sulfate fractionation, Sephadex G-100, DEAE-Cellulose and Phenyl-Sepharose CL4B column chromatography with overall yield of 16%. It showed an molecular weight of 34.7 kDa by SDS-polyacrylamide gel electrophoresis. The enzyme activity with tributyrin as substrate was optimal at pH 8.0~9.0 and at $37^{\circ}C$. The enzyme activity decreased when the chain length of acyl group of triacyglycerol increased. A-factor, a hormone-like regulator of Streptomyces differentiation inhibited the lipase activity, which might corelate with the low enzyme activity in early exponential growth phase.

• Journal of Bio-Environment Control
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• v.31 no.4
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• pp.460-467
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• 2022

The purpose of this study is to enhance utilization of the waste nutrient solution (WNS) disposed at the hydroponic greenhouse. Several sets of testing were conducted to examine the effects of WNS: (a) a fertilizer effect, (b) soil column leaching, and (c) crop cultivation. The fertilizer effect test was applied in young radish cultivation by examining the growth characteristics of young radish and soil based on inorganic nitrogen according to the soil treatment of the nitrogen fertilizer (NF) and the WNS. The fertilizer effects and crop cultivation test were conducted with five treatments (A-E): A, non-treatment (water); B, 100% of NF; C, 70% of NF + 30% of WNS; D, 50% of NF + 50% of WNS; and E, 30% of NF + 70% of WNS. The soil column leaching test was conducted with three treatments: non-treatment (water), 100% of NF, 50% of WNS + 50% of NF. As a result, the chemical properties of the WNS were pH 6.0, EC 2.4dS·m^-1, total phosphorus (T-P) 28mg·L^-1, ammonium nitrogen (NH₄-N) 5.0mg·L^-1, and nitrate nitrogen (NO₃-N) 301mg·L^-1. The chemical properties of the soil were pH 5.51, EC 0.31dS/m, organic matter 2.08g·kg^-1, NO₃-N 9.64mg·kg^-1, and NH₄-N 3.20mg·kg^-1. The results of fertilizer effects showed that the ratio of 50% or less of NF and 50% or more of WNS was high in young radish growth. There was no statistically significant difference between the soil chemistry in the C-E treatments where WNS was mixed with NF and the B treatment where only NF was applied. As a result of the soil column leaching test, there was no significant difference in the concentrations of NO₃ and NH₄ in the treatment of 100% of NF and 50% of NF + 50% of WNS. The study indicates, if the mixed fertilizer of WNS and NF is applied in the soil cultivation of young radish, it will reduce the use of NF and environmental pollution. This also helps reduce production costs on farmers and increase the yield of young radish.

• Elastomers and Composites
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• v.51 no.4
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• pp.286-300
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• 2016

$MoS_2$ precursors were synthesized by reacting thioacetamide ($C_2H_5NS$) with sodium molybdate dihydrate ($Na_2MoO_4{\cdot}2H_2O$) in aqueous HCl solution. $MoS_2$ nanoparticles were prepared from dried $MoS_2$ precursors by calcination in an electric furnace at $700^{\circ}C$ for 2 h under an inert argon atmosphere. $MoS_2-C_{60}$ nanocomposites were obtained by heating $MoS_2$ nanoparticles and fullerene ($C_{60}$) together in an electric furnace at $700^{\circ}C$ for 2 h. Their morphological and the structural properties were characterized by powder X-ray diffraction and scanning electron microscopy. The $MoS_2$ nanoparticles and $MoS_2-C_{60}$ nanocomposites were used as catalysts in the reductions of 2-, 3-, and 4-nitrophenol in the presence of sodium borohydride. The photocatalytic activities of the $MoS_2$ nanoparticles and $MoS_2-C_{60}$ nanocomposites were evaluated in the degradation of organic dyes (brilliant green, methylene blue, methyl orange, and rhodamine B) under ultraviolet light (254 nm).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.12 no.1
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• pp.62-68
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• 1999

Ferroelectric $Sr_{0.7}/B_{2.3}(Ta_{1-x}Nb_x)_2O_9$(x=0, 0.1, 0.2, 0.3) thin films were deposited on $Pt/SiO_2/Si$ substrate by MOD(Metalorganic Decomposition) process. Metal carboxylate and metal alkoxide were used as precursors, and 2-methoxyethanol, xylene as solvents. After spin coating, thin films were pre-annealed at $400^{\circ}C$, followed by RTA(Rapid Thermal Annealing) and final annealing at $800^{\circ}C$ in oxygen atmosphere. These procedures were repeated three times to obtain thin films with the thickness of $2000{\AA}$. To enhance the nucleation and growth of layered-perovskite phase, thin films were rapid-thermally annealed above $720^{\circ}C$ in oxygen atmosphere. As RTA temperature increased, fluorite phase was transformed to layered-perovskite phase. And the change of Nb contents affected dielectric / electrical properties and microstructure. The ferroelectric characteristics of $Sr_{0.7}/B_{2.3}(Ta_{1-x}Nb_x)_2O_9$ thin film were Pr=8.67 $\mu{C}/cm^2$, Ec=62.4kV/cm and $I_{L}=1.4\times10^{-7}A/cm^2$ at the applied voltage of 5V, respectively.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3221-3224
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• 2010

This study investigates the requirements of lithium-air cathodes, which directly influence discharge capacity. The cathodes of Li-air cell are made by using five different carbon materials, such as Ketjen black EC600JD, Super P, Ketjen black EC300JD, Denka black, and Ensaco 250G. The Ketjen black EC600JD provides discharge capacity of 2600 mAh/g per carbon weight, while that of Ensaco 250G shows only 579 mAh/g. To figure out the differences of discharge capacity from carbon materials, their surface area and pore volume are analyzed. These are found out to be the critical factors in determining discharge capacity. Furthermore, carbon loading on Ni foam and amounts of electrolyte are significant factors that affect discharge capacity. In order to investigate catalyst effect, electrolytic manganese dioxide (EMD) is incorporated and delivered 4307 mAh/g per carbon weight. This infers that EMD facilitates to break $O_2$ interactions and leads to enhance discharge capacity.

• Transactions on Electrical and Electronic Materials
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• v.1 no.1
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• pp.22-25
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• 2000

Polycrystalline SBTN layered ferroelectric thin film with various Nb mole ratios were prepared by sol-gel method Pt/ $SiO_2$/Si (100) substrates. The films were annealed at different temperature and characterized in terms of phase and microstructure. The films were crystallized with a high (105) diffraction intensity and had rodike structure, SBTN films fired at 800$^{circ}C$ revealed standard hysteresis loops with no fatigue for up to 10$^{10}$ cycles. At an applied voltage of 5V the dielectric constant($varepsilon$) , dissipation factor (tan $delta$), remanent polarization(ZPr) and coercive field(Ec) of typical S $r_{0.8}$B $i_{2.3}$(T $a_{1-x}$ N $b_{x}$) $O_{9+}$$alpha$/ thin film(x=0.1) prepared on Pt/ $SiO_2$/Si (100) were about 277.7, 0.042, 3.74$mu$C/$textrm{cm}^2$, and 24.8kv/cm respectively.ly.y. respectively.ly.y.y..