• Biomolecules & Therapeutics
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• 제19권3호
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• pp.288-295
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• 2011

Amyloid beta ($A{\beta}$)-induced neurotoxicity is a major pathological mechanism of Alzheimer's disease (AD). In this study, we investigated the inhibitory effect of L-theanine, a component of green tea (Camellia sinensis) on $A{\beta}_{1-42}$-induced neurotoxicity and oxidative damages of macromolecules. L-theanine inhibited $A{\beta}_{1-42}$-induced generation of reactive oxygen species, and activation of extracellular signal-regulated kinase and p38 mitogenic activated protein kinase as well as the activity of nuclear factor kappa-B. L-theanine also signifi cantly reduced oxidative protein and lipid damage, and elevated glutathione level. Consistent with the reduced neurotoxic signals, L-theanine (10-50 ${\mu}g$/ml) concomitantly attenuated $A{\beta}_{1-42}$ (5 ${\mu}M$)-induced neurotoxicity in SK-N-MC and SK-N-SH human neuroblastoma cells. These data indicate that L-theanine on $A{\beta}$-induced neurotoxicity prevented oxidative damages of neuronal cells, and may be useful in the prevention and treatment of neurodegenerative disease like AD.

• 대한임상검사과학회지
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• 제51권3호
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• pp.360-369
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• 2019

Cadherin은 원형질막에 존재하며 세포-세포 결합에 관여하며, 황체 구조 유지에 필수적인 단백질이다. 본 연구에서는 prostaglandin F2 alpha ($PGF2{\alpha}$)가 황체의 협막세포(luteal theca cells, LTCs)의 E-cadherin, N-cadherin 및 세포-세포부착에 미치는 영향에 대해서 수행하였다. 황체세포는 소의 황체중기 조직으로부터 분리하였으며, 황체세포 중에서 mesenchymal 세포 형태학적 특성을 가지는 세포만을 분리하여 LTCs로 판단하였다. 이 후 steroidogenic 기능 및 혈관세포 유무를 판단하기 위해 $3{\beta}$-HSD 및 VEGF2R mRNA 발현을 확인하였으며, E-cadherin 및 N-cadherin mRNA를 사용하여 LTCs 내 cadherin의 존재여부를 판단하였다. 또한 0, $10^{-5}$, $10^{-4}$ 및 $10^{-3}M$ $PGF2{\alpha}$를 24시간 동안 처리하여 LTCs의 E- 및 N-cadherin 단백질을 관찰한 후 세포-세포 접착 실험을 실시하였다. 그 결과, LTCs에서 $3{\beta}$-HSD mRNA가 발현되었지만, VEGFR2 mRNA는 발현되지 않았으며, E-cadherin 및 N-cadherin mRNA 모두 발현되는 것을 확인하였다. 또한 E-및 N-cadherin 단백질은 $10^{-5}$, $10^{-4}$ 및 $10^{-3}M$ $PGF2{\alpha}$를 처리한 LTCs에서 응집되어 발현되는 것을 확인하였으며, $PGF2{\alpha}$에 의해 LTCs의 세포부착 효율이 유의적으로 감소된 것을 확인하였다. 결론적으로 $PGF2{\alpha}$는 LTCs의 E- 및 N-cadherin을 붕괴시켜 세포부착을 감소시켰고, 이러한 결과는 황체퇴행의 새로운 원인을 밝혀 내기 위한 cadherin과 세포부착의 역할을 이해하는데 중요한 자료로 활용될 것으로 판단된다.

• 한국균학회소식:학술대회논문집
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• 한국균학회 2016년도 춘계학술대회 및 임시총회
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• pp.27-27
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• 2016

The ascomycete fungus Fusarium graminearum is the most common pathogen of Fusarium head blight (FHB), a devastating disease for major cereal crops worldwide. FHB causes significant crop losses by reducing grain yield and quality as well as contaminating cereals with trichothecenes and zearalenone (ZEA) that pose a serious threat to animal health and food safety. ZEA is a causative agent of hyperestrogenic syndrome in mammals and can result in reproductive disorders in farm animals. In F. graminearum, the ZEA biosynthetic cluster is composed of four genes, PKS4, PKS13, ZEB1, and ZEB2, which encode a reducing polyketide synthase, a nonreducing polyketide synthase, an isoamyl alcohol oxidase, and a transcription factor, respectively. Although it is known that ZEB2 primarily acts as a regulator of ZEA biosynthetic cluster genes, the mechanism underlying this regulation remains undetermined. In this study, two isoforms (ZEB2L and ZEB2S) from the ZEB2 gene in F. graminearum were characterized. It was revealed that ZEB2L contains a basic leucine zipper (bZIP) DNA-binding domain at the N-terminus, whereas ZEB2S is an N-terminally truncated form of ZEB2L that lacks the bZIP domain. Interestingly, ZEA triggered the induction of both ZEB2L and ZEB2S transcription. In ZEA producing condition, the expression of ZEB2S transcripts via alternative promoter usage was directly or indirectly initiated by ZEA. Physical interaction between ZEB2L and ZEB2L as well as between ZEB2L and ZEB2S was observed in the nucleus. The ZEB2S-ZEB2S interaction was detected in both the cytosol and the nucleus. ZEB2L-ZEB2L oligomers activated ZEA biosynthetic cluster genes, including ZEB2L. ZEB2S inhibited ZEB2L transcription by forming ZEB2L-ZEB2S heterodimers, which reduced the DNA-binding activity of ZEB2L. This study provides insight into the autoregulation of ZEB2 expression by alternative promoter usage and a feedback loop during ZEA production.

• 한국환경과학회지
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• 제9권4호
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• pp.311-318
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• 2000

To improve $CO_2$pemselectivity, a modified silica membrane was prepared by chemical vapor deposition with tetraethoxysilane(TEOS)-ethanol-water, and TEOS-ethanol-water-HCI solution at 300-$600^{\circ}C$. The silica was effectively deposited in the mesopores of a ${\gamma}$-alumina film coated on a porous $\alpha$-alumina tube by evacuating the reactants through the porous wall. In this membrane, $CO_2$interacts, to some extent, with the pore wall, and $CO_2$/$N_2$selectivity then exceeds the value of the Knudsen diffusion mechanism, while the membrane derived from TEOS alone has no $CO_2$selectivity. The silica membrane prepared from TEOS-ethanol-water-HCI solution showed that $CO_2$permeance was $2.5$\times$10^{-7}mol/s^{-1}.m^{-2}.Pa^{-1} at 30{\circ}C$ and $CO_2$/$N_2$selectivity was approximately 3. The $CO_2$permeance and selectivity was improved by enlarging the surface diffusion with modification of chemical affinity of the silica pores.

• Elastomers and Composites
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• 제13권4호
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• pp.277-281
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• 1978

우수한 가황(加黃)지연제는 MBT와 빠른 속도(速度)로 반응(反應)하여 스코오치타임이 긴 가황촉진제(加黃促進劑)인 2-싸이클로헥실디티 오벤쪼티아쫄(CDB)을 생성(生成)한다. 이것은 CDB를 분리(分離)하여 고무에 배합(配合)한 후(後) 가황특성(加黃特性)을 측정(測定)함으르서 확인(確認)된 것이다. N-(싸이클로핵실티오)프탈이미드(CTP)와 같은 새로운 가황지연제는 가황중(加黃中) 싸이클로헥실폴리썰파이드(CPS)를 생성(生成)하며 이 CPS가 황(黃)을 공급(供給)할 수 없음으로 일부(一部)의 황(黃)이 낭비되므로 따라서 CTP를 사용(使用)할 때에는 추가(追加)의 황(黃을) 사용(使用)하여야만 만족(滿足)할만한 여러 물성치(物性値)를 갖춘 가황체(加黃體를) 얻을 수가 있다. CDB의 늦은 가황속도(加黃速度)를 인지(認知)하므로서 CTP와 같은 가황지연제를 사용(使用)할 때에 가황속도(加黃速度)가 늦는 이유(理由)를 이해할 수가 있는 것이다.

• Asian-Australasian Journal of Animal Sciences
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• 제18권1호
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• pp.133-140
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• 2005

Although amino acids are substrates for the synthesis of proteins and nitrogen-containing compounds, it has become more and more clear over the years that these nutrients are also extremely important as regulators of body protein turnover. The branched-chain amino acids (BCAAs) together or simply leucine alone stimulate protein synthesis and inhibit protein breakdown in skeletal muscle. However, it was only recently that the mechanism(s) involved in the regulation of protein turnover by BCAAs has begun to be defined. The acceleration of protein synthesis by these amino acids seems to occur at the level of peptide chain initiation. Oral administration of leucine to food-deprived rats enhances muscle protein synthesis, in part, through activation of the mRNA binding step of translation initiation. Despite our knowledge of the induction of protein synthesis by BCAAs, there are few studies on the suppression of protein degradation. The recent findings that oral administration of leucine rapidly reduced $N^{\tau}$-methylhistidine (3-methylhistidine; MeHis) release from isolated muscle, an index of myofibrillar protein degradation, indicate that leucine suppresses myofiblilar protein degradation. The details of the molecular mechanism by which leucine inhibits proteolysis is just beginning to be elucidated. The purpose of this report was to review the current understanding of how BCAAs act as regulators of protein turnover.

• Bulletin of the Korean Chemical Society
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• 제33권8호
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• pp.2483-2488
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• 2012

The X-ray line broadening technique was used to calculate the grain size of MgO at 1023, 1123, 1223 K respectively either in $CO_2$ or during the thermal decomposition of magnesites in air as well as in vacuum. By referring to the conventional grain growth equation, $D^n=kt$, the activation energy and pre-exponential factor for the process in air are gained as 125.8 kJ/mol and $1.56{\times}10^8\;nm^4/s$, respectively. Ranman spectroscopy was employed to study the surface structure of MgO obtained during calcination of magnesite, by which the mechanism of grain growth was analyzed and discussed. It is suggested that a kind of highly reactive MgO is produced during the thermal decomposition of magnesites, which is exactly the reason why the activation energy of the grain growth during the thermal decomposition of magnesite is lower than that of bulk diffusion or surface diffusion.

• Archives of Pharmacal Research
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• 제16권4호
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• pp.276-282
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• 1993

This study has been undertaken to examine the effect of 3-methylcholanthrene (3MC) on rat uterine growth and to understand the mechanism of action of 3MC in rat uterus. After diethylstilbesterol(DES) or tamoxifen(TAM) or 3MC or DES plus TAM or DES plus 3MC was administered into immature female rats, uterine weight over corn oil-treated uteri. 3MC treatment had no effect on uterine weight but, DES stimulated uterine weight was inhibited by 3MC concomitant tratment. While TAM alone treatment showed slight increase in uterine wieght, inhibited uterine growth simulated by DES when it was adiministrated with DES condirect binding assay with $[^3H]$ estradiol and the relative binding affinities of 3MC and TAM were estimated by competetion assy. Estradiol tumed out to have high affinity for rat uterine estrogen receptor (kd = 0.4 nM). The relative binding affinities of TAM and 3MC were 1% and 4.7% that of DES for rat uterine estrogen receptor, respectively. 3MC was shown to have similar affinity for eat uterine estrogen receptor to that of TAM. Effects of DES 3MC and TAM administration in vivo on rat uterine estrogen recptor level were examined. It was confirmed that the estrogen, DES and antiestrogen, TAM decreased estrogen receptor levels from rat ulterus and also 3MC decreased rat uterine estrogen receptor level when rats were treated with DES, TAM and 3MC in vivo. Data indicates that 3MC acts as an antiestrogen mediated through estrogen receptor system.

• 약학회지
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• 제57권6호
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• pp.388-393
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• 2013

Previously, we have reported that lovastatin, an inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, increased melanin synthesis through intracellular $Ca^{2+}$ release in B16 cells. In this study we investigated the possible involvement of nitric oxide (NO) in the mechanism of lovastatin-induced melanogenesis. Lovastatin elevated NO formation in a dose-dependent manner. Treatment with mevalonate, farnesyl pyrophosphate (FPP) and geranylgeranyl pyrophosphate (GGPP), precursors of cholesterol, did not significantly alter the lovastatin-induced NO production, suggesting that inhibition of cholesterol metabolism may not be involved in the mechanism of this action of lovastatin. Both NO formation and melanogenesis induced by lovastatin was significantly suppressed by treatment with $N^G$-nitro-L-arginine methyl ester (L-NAME) and 2-(4-carboxy-2-phenyl)-4,4,5,5-tetramethylinidazoline-1-oxyl-3-oxide (cPTIO), an inhibitor of NO synthase and a NO scavenger, respectively. The lovastatin-induced NO production was significantly affected not by EGTA, an extracellular $Ca^{2+}$ chelator, but by an intracellular $Ca^{2+}$ chelator (BAPTA/AM) and intracellular $Ca^{2+}$ release blockers (dantrolene and TMB-8). Taken together, these results suggest that lovastatin may induce melanogenesis through NO formation mediated by intracellular $Ca^{2+}$ release in B16 cells. These results further suggest that lovastatin may be a good candidate for the therapeutic application of various hypopigmentation disorders.

• 한국재료학회지
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• 제33권6호
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• pp.229-235
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• 2023

An all-perovskite oxide heterostructure composed of SrSnO₃/Nb-doped SrTiO₃ was fabricated using the pulsed laser deposition method. In-plane and out-of-plane structural characterization of the fabricated films were analyzed by x-ray diffraction with θ-2θ scans and φ scans. X-ray photoelectron spectroscopy measurement was performed to check the film's composition. The electrical transport characteristic of the heterostructure was determined by applying a pulsed dc bias across the interface. Unusual transport properties of the interface between the SrSnO₃ and Nb-doped SrTiO₃ were investigated at temperatures from 100 to 300 K. A diodelike rectifying behavior was observed in the temperature-dependent current-voltage (IV) measurements. The forward current showed the typical IV characteristics of p-n junctions or Schottky diodes, and were perfectly fitted using the thermionic emission model. Two regions with different transport mechanism were detected, and the boundary curve was expressed by ln I = -1.28V - 13. Under reverse bias, however, the temperature- dependent IV curves revealed an unusual increase in the reverse-bias current with decreasing temperature, indicating tunneling effects at the interface. The Poole-Frenkel emission was used to explain this electrical transport mechanism under the reverse voltages.