• 한국응용과학기술학회지
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• 제29권3호
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• pp.531-542
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• 2012

본 논문은 바이오폴리우레탄의 연구동향에 관한 것이다. 바이오폴리우레탄은 원료 중의 식물유 폴리올과 이소시아네이트의 중부가 고분자이다. 피마자유의 주성분은 히드록시기를 갖는 리시놀산의 트리글리세라이드이다. 이외의 히드록시기가 없는 식물유는 이중결합 위치에서 에폭시화 후 고리열림, 히드로포르밀화 후 수소첨가, 가오존분해 후 수소첨가, 티올-엔 반응으로 히드록시기를 부여한다. 폴리올의 반응성 및 마이크로도메인의 모폴로지 조절을 위한 하이퍼브랜치 폴리올, 일차 알코올 폴리올, 다당류 폴리올이 있다. 의료용의 생분해성 폴리락트산 폴리올, 가수분해 방지용 지방산 다이머 폴리올, 이온성 기를 함유한 수 분산 폴리우레탄용 폴리올이 있다. 바이오폴리올을 이용한 바이오폴리우레탄은 경질 및 연질 폼, 코팅제, 접착제, 실런트, 엘라스토머에 쓰인다.

• Asian-Australasian Journal of Animal Sciences
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• 제27권3호
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• pp.342-348
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• 2014

This study was conducted to examine the effects of condensed tannins (CT) from Ficus bengalensis leaves on the feed utilization, milk production and health status of crossbred cows. Eighteen crossbred dairy cows at their second and mid lactation (avg. BW $351.6{\pm}10.6$ kg) were randomly divided into two groups of nine each in a completely randomized block design and fed two iso-nitrogenous supplements formulated to contain 0% and 1.5% CT through dried and ground leaves of Ficus bengalensis. The diets were designated as CON and FBLM, respectively and fed to cows with a basal diet of rice straw to meet requirements for maintenance and milk production. The daily milk yield was significantly (p<0.05) increased due to supplementation of FBLM diet. The 4% fat corrected milk yield was also significantly (p<0.01) higher due to increased (p<0.05) milk fat in cows under diet FBLM as compared to CON. The inclusion of CT at 1.5% in the supplement did not interfere with the feed intake or digestibility of DM, OM, CP, EE, NDF, and ADF by lactating cows. Digestible crude protein (DCP) and total digestible nutrients (TDN) values of the composite diets were comparable between the groups. The blood biochemical parameters remained unaltered except significantly (p<0.05) lowered serum urea concentration in cows fed FBLM diet. There was a significant (p<0.05) increase intracellular reduced glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) activity in cows supplemented with condensed tannins. The total thiol group (T-SH) was found to be higher with reduction in lipid peroxidation (LPO) in cows of FBLM group. The cost of feeding per kg milk production was also reduced due to supplementation of Ficus bengalensis leaves. Therefore, a perceptible positive impact was evident on milk production and antioxidant status in crossbred cows during mid-lactation given supplement containing 1.5% CT through Ficus bengalensis leaves.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.31-32
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• 2010

In our previous reports [1-3], electron transport for the switching and memory devices using alkyl thiol-tethered Ru-terpyridine complex compounds with metal-insulator-metal crossbar structure has been presented. On the other hand, among organic memory devices, a memory based on the OFET is attractive because of its nondestructive readout and single transistor applications. Several attempts at nonvolatile organic memories involve electrets, which are chargeable dielectrics. However, these devices still do not sufficiently satisfy the criteria demanded in order to compete with other types of memory devices, and the electrets are generally limited to polymer materials. Until now, there is no report on nonvolatile organic electrets using nano-interfaced organic monomer layer as a dielectric material even though the use of organic monomer materials become important for the development of molecularly interfaced memory and logic elements. Furthermore, to increase a retention time for the nonvolatile organic memory device as well as to understand an intrinsic memory property, a molecular design of the organic materials is also getting important issue. In this presentation, we report on the OFET memory device built on a silicon wafer and based on films of pentacene and a SiO2 gate insulator that are separated by organic molecules which act as a gate dielectric. We proposed push-pull organic molecules (PPOM) containing triarylamine asan electron donating group (EDG), thiophene as a spacer, and malononitrile as an electron withdrawing group (EWG). The PPOM were designed to control charge transport by differences of the dihedral angles induced by a steric hindrance effect of side chainswithin the molecules. Therefore, we expect that these PPOM with potential energy barrier can save the charges which are transported to the nano-interface between the semiconductor and organic molecules used as the dielectrics. Finally, we also expect that the charges can be contributed to the memory capacity of the memory OFET device.[4]

• 대한약침학회지
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• 제22권3호
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• pp.160-165
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• 2019

Objectives: The aim of this study was to evaluate the effect of Ribes khorasanicum (R. khorasanicum); a plant growing in north Khorasan of Iran; on cardiovascular and stress oxidative in acute hypertension induced by N-nitro-l-arginine methyl ester (L-NAME), anitric oxide synthase inhibitor. Methods: Rats were divided into Control, L-NAME (10 mg/kg), Sodium Nitroprusside (SNP) (50 mg/kg) + L-NAME and three treated groups with R. khorasanicum (4, 12 and 24 mg/kg) groups + L-NAME. L-NAME and SNP were injected intravenously and extract intraperitoneal. In R. khorasanicum groups, L-NAME was injected 30 min after injection of the extract. Systolic blood pressure (SBP), mean arterial pressure (MAP) and heart rate (HR) were recorded continuously using power lab software. At the end of study oxidative stress parameters including of total thiol content (SH), malondialdehyde (MDA), superoxide dismutase (SOD) and catalase (CAT) in heart and aorta of all groups were also measured. Results: In groups 4 and 24 mg/kg extract +L-NAME, there was a non-significant decrease in SBP and MAP compared to L-NAME group but dose 12 mg/kg significantly attenuate the effect of L-NAME(P < 0.05). In L-NAME group the heart and aorta tissues antioxidant enzymes levels decreased, while in treated rats these enzymes significantly increased. Conclusion: The extract of R. khorasanicum in dose 12 mg/kg show anti-hypertensive effect that is mediated by an effect on NO system or antioxidant parameters.

• 생명과학회지
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• 제16권6호
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• pp.1052-1059
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• 2006

다양한 종류의 박테리아에서부터 사람의 세포에 이르기까지 환경적인 스트레스나 병에 의한 스트레스 혹은 스트레스가 없는 상황에서도 열충격반응(heat shock response) 유도되어진다. 열충격반응에 노출된 세포에서는 모든 단백질의 발현이 정지되는 반면, 열충격단백질(heat shock proteins: HSPs)은 발현되어 스트레스로부터 세포를 보호한다. HSF1(heat shock factor 1)이라는 HSPs 유도단백질은 열충격반응시 단량체형태에서 삼중체의 형태로 구조변화를 일으켜 heat shock element(HSE)라고 불리우는 HSP gene의 발현 promoter에 특이적으로 결합하게 되어 HSPs를 발현시킨다. Human HSF1(hHSF1)은 다섯 개의 시스테인 잔기를 가지고 있는데 이 시스테인의 thiol(-SH)기는 강한 친전자성을 띔으로 급격히 산화되거나 질산화된다. 이러한 고찰은 시스테인 잔기가 산화 환원 의존적인 황산기/이황화결합 전환을 통해 구조적인 변화를 가져온다는 사실을 의미하고 있다. 따라서 본 연구에서는 여러 가지 산화환원제를 이용하여 HSF1에 존재하는 다섯 개의 시스테인 잔기의 역할과 삼량체 형성에 관여하는 잔기에 대하여 알아보고자 하였다. 또한 이황화결합을 통한 삼량체형성의 구조적변화의 관점에서 HSF1의 구조 변화와 DNA 결합력과의 상관관계에 관하여도 알아보고자 하였다. 본 연구결과로 HSF1의 DNA binding domain은 삼량체를 형성하는 구조적인 변화를 통해서 DNA에 대한 결합력이 증가되는 것을 알 수 있었는데 이것은 삼량체가 됨으로서 HSF1의 내부에 위치해 있던 DNA binding domain이 외부로 노출 되어져 DNA에 쉽게 결합할 수 있게 된다는 사실을 시사한다.

• Archives of Pharmacal Research
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• 제21권6호
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• pp.683-687
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• 1998

We have examined in vitro and in vivo radioprotective effects of a well-known thiol-containing compound, dithiothreitol (DTT). The treatment of both 0.5 and 1mM of DTT significantly increased clonogenic survival of ${\gamma}$-ray irradiated Chinese hamster (V79-4) cells. In order to investigate the possible radioprotective mechanism of DTT, we measured gamma-ray induced chromosome aberration by micronucleus assay. In the presence of 0.5mM or 1mM DTT, the frequencies of micronuclei were greatly reduced in all dose range examined (1.5-8 GY). Slightly higher reduction in micronucleus formation was observed in 1mM DTT-treated cells than in 0.5mM DTT-treated cells. In addition, incubation with both 0.5 and 1mM of DTT prior to gamma-ray irradiation reduced nucleosomal DNA fragmentation at about same extent, this result suggests that treatment of DTT at concentrations of 0.5 and 1mM reduced radiation-induced apoptosis. In vivo experiments, we also observed that DTT treatment reduced the incidence of apoptotic cells in mouse small intestine crypts. In irradiated control group 4.4${\pm}$0.5 apoptotic cells per crypt were observed. In DTT-administered and irradiated mice, only 2.1${\pm}$0.4 apoptotic cells per crypt was observed. In vitro and in vivo data obtained in this study showed that DTT reduced radiation-induced damages and it seems that the possible radioprotective mechanisms of action of DTT are prevention of chromosome aberration.

• Archives of Pharmacal Research
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• 제25권6호
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• pp.801-806
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• 2002

Cyclicpeptides are important targets in peptide synthesis because of their interesting biological properties. Constraining highly flexible linear peptides by cyclization is one of the mostly widely used approaches to define the bioactive conformation of peptides. Cyclic peptides often have increased receptor affinity and metabolic stability over their linear counterparts. We carried out virtual screening experiment via docking in order to understand the interaction between HLE-Human Leukocyte Elastase and ligand peptide and to identify the sequence that can be a target in various ligand peptides. We made cyclic peptides as a target base on Metlle-Phe sequence having affinity for ligand and receptor active site docking. There are three ways to cyclize certain sequences of amino acids such as Met-lie-Phe-Gly-Ile. First is head-to-tail cyclization method, linking between N-terminal and C-terminal. Second method utilizes amino acid side chain such as thiol functional group in Cys, making a thioether bond. The last one includes an application of resin-substituted amino acids in solid phase reaction. Among the three methods, solid phase reaction showed the greatest yield. Macrocyclization of Fmoc-Met-Ile-Phe-Gly-Ile-OBn after cleavage of Fmoc protection in solution phase was carried out to give macrocyclic compound 5 in about 7% yield. In the contrast with solution phase reaction, solid phase reaction for macrocyclization of Met-Ile-Phe-Gly-Ile-Asp-Tentagel in normal concentrated condition gave macrocyclic compound 7 in more than 35% yield.

• BMB Reports
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• 제32권4호
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• pp.414-418
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• 1999

A novel gene for malonyl-CoA decarboxylase was discovered in the mat operon, which encodes a set of genes involved in the malonate metabolism of Rhizobium trifolii (An and Kim, 1998). The subunit mass determined by SDS-PAGE was 53 kDa, which correspond to the deduced mass from the sequence data. The molecular mass of the native enzyme determined by field flow fractionation was 208 kDa, indicating that R. trifolii malonyl-CoA decarboxylase is homotetrameric. R. trifolii malonyl-CoA decarboxylase converted malonyl-CoA to acetyl-CoA with a specific activity of 100 unit/mg protein. Methylmalonyl-CoA was decarboxylated with a specific activity of 0.1 unit/mg protein. p-Chloromercuribenzoate inhibited this enzyme activity, suggesting that thiol group(s) is(are) essential for this enzyme catalysis. Database analysis showed that malonyl-CoA decarboxylase from R. trifolii shared 32.7% and 28.1% identity in amino acid sequence with those from goose and human, respectively, and it would be located in the cytoplasm. However, there is no sequence homology between this enzyme and that from Saccharopolyspora erythreus, suggesting that malonyl-CoA decarboxylases from human, goose, and R. trifolii are in the same class, whereas that from S. erythreus is in a different class or even a different enzyme, methylmalonyl-CoA decarboxylase. According to the homology analysis, Cys-214 among three cysteine residues in the enzyme was found in the homologous region, suggesting that the cysteine was located at or near the active site and plays a critical role in catalysis.

• BMB Reports
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• 제30권6호
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• pp.397-402
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• 1997

A thiol-specific spin label was attached to cysteine-102 of yeast cytochrome c and electron paramagnetic resonance (EPR) spectra were measured as a function of added cytochrome c oxidase concentration. The intensity decreased due to line broadening as cytochrome c formed a complex with cytochrome c oxidase and reached a minimum when the ratio of cytochrome c to cytochrome c oxidase became one. Replacement of either Lys-72 or Lys-87 of cytochrome c by Glu did not result in a significant change in binding affinity. Interestingly the K72E mutant, unlike K87E, had a much lower rate of electron transfer than the wild type. These results indicate that many positively charged residues as a group participate in complex formation but Lys-72 might be important for cytochrome c to be locked in an orientation for an efficient electron transfer. A stoichiometry of 1 was also confirmed by optical absorption of the cytochrome c-cytochrome c oxidase complex which had been run through a gel chromatography cloumn to remove unbound cytochrome c. The EPR spectrum of this 1:1 complex, however, was a mixture of two components. This explains a biphasic kinetics for a single binding site on cytochrome c oxidase without invoking conformational transition.

• International Journal of Oral Biology
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• 제33권3호
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• pp.117-123
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• 2008

Reactive oxygen species (ROS) are toxic agents that may be involved in various neurodegenerative diseases. Recent studies indicate that ROS can act as modulators of neuronal activity, and are critically involved in persistent pain primarily through spinal mechanisms. In the present study, whole cell patch clamp recordings were carried out to investigate the effects of tert-buthyl hydroperoxide (t-BuOOH), an ROS, on neuronal excitability and the mechanisms underlying changes of membrane excitability. In current clamp condition, application of t-BuOOH caused a reversible membrane depolarization and firing activity in substantia gelatinosa (SG) neurons. When slices were pretreated with phenyl-N-tert-buthylnitrone (PBN) and ascorbate, ROS scavengers, t-BuOOH failed to induce membrane depolarization. However, isoascorbate did not prevent t-BuOOH-induced depolarization, suggesting that the site of ROS action is intracellular. The t-BuOOH-induced depolarization was not blocked by pretreatment with dithiothreitol (DTT), a sulfhydryl-reducing agent. The membrane-impermeant thiol oxidant 5,5-dithiobis 2-nitrobenzoic acid (DTNB) failed to induce membrane depolarization, suggesting that the changes of neuronal excitability by t-BuOOH are not caused by the modification of extrathiol group. The t-BuOOH-induced depolarization was suppressed by the phospholipase C (PLC) blocker U-73122 and inositol triphosphate ($IP_3$) receptor antagonist 2-aminoethoxydiphenylbolate (APB), and after depletion of intracellular $Ca^{2+}$ pool by thapsigargin. These data suggest that ROS generated by peripheral nerve injury can induce central sensitization in spinal cord, and t-BuOOH-induced depolarization may be regulated by intracellular $Ca^{2+}$ store mainly via $PLC-IP_3$ pathway.