• Restorative Dentistry and Endodontics
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• v.27 no.5
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• pp.543-551
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• 2002

Nitric oxide (NO) is a small molecule (mol. wt. 30 Da) and oxidative free radical. It is uncharged and can therefore diffuse freely within and between cells across membrane. Such characteristics make it a biologically important messenger in physiologic processes such as neurotransmission and the control of vascular tone. NO is also highly toxic and is known to acts as a mediator of cytotoxicity during host defense. NO is synthesized by nitric oxide synthase (NOS) through L-arginine/nitric oxide pathway which is a dioxygenation process. NO synthesis involves several participants, three co-substrates, five electrons, five co-factors and two prosthetic groups. Under normal condition, low levels of NO are synthesized by type I and III NOS for a short period of time and mediates many physiologic processes. Under condition of oxidant stress, high levels of NO are synthesized by type II NOS and inhibits a variety of metabolic processes and can also cause direct damage to DNA. Such interaction result in cytostasis, energy depletion and ultimately cell death. NO has the potential to interact with a variety of intercellular targets producing diverse array of metabolic effects. It is known that NO is involved in hemodynamic regulation, neurogenic inflammation, re-innervation, management of dentin hypersensitivity on teeth. Under basal condition of pulpal blood flow, NO provides constant vasodilator tone acting against sympathetic vasoconstriction. Substance P, a well known vasodilator, was reported to be mediated partly by NO, while calcitonin-gene related peptide has provided no evidence of its relation with NO. This review describes the roles of NO in dental pulp in addition to the known general roles of it.

• Fisheries and Aquatic Sciences
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• v.20 no.7
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• pp.9.1-9.13
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• 2017

Background: Metal-responsive transcription factor-1 (MTF-1) is a key transcriptional regulator playing crucial roles in metal homeostasis and cellular adaptation to diverse oxidative stresses. In order to understand cellular pathways associated with metal regulation and stress responses in Pacific abalone (Haliotis discus hannai), this study was aimed to isolate the genetic determinant of abalone MTF-1 and to examine its expression characteristics under basal and experimentally stimulated conditions. Results: The abalone MTF-1 shared conserved features in zinc-finger DNA binding domain with its orthologs; however, it represented a non-conservative shape in presumed transactivation domain region with the lack of typical motifs for nuclear export signal (NES) and Cys-cluster. Abalone MTF-1 promoter exhibited various transcription factor binding motifs that would be potentially related with metal regulation, stress responses, and development. The highest messenger RNA (mRNA) expression level of MTF-1 was observed in the testes, and MTF-1 transcripts were detected during the entire period of embryonic and early ontogenic developments. Abalone MTF-1 was found to be Cd inducible and highly modulated by heat shock treatment. Conclusion: Abalone MTF-1 possesses a non-consensus structure of activation domains and represents distinct features for its activation mechanism in response to metal overload and heat stress. The activation mechanism of abalone MTF-1 might include both indirect zinc sensing and direct de novo synthesis of transcripts. Taken together, results from this study could be a useful basis for future researches on stress physiology of this abalone species, particularly with regard to heavy metal detoxification and thermal adaptation.

• The Korean Journal of Physiology and Pharmacology
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• v.18 no.2
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• pp.129-134
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• 2014

It has been suggested that transition metal ions such as iron can produce an oxidative injuries to nigrostriatal dopaminergic neurons, like Parkinson's disease (PD) and subsequent compensative increase of tetrahydrobiopterin ($BH_4$) during the disease progression induces the aggravation of dopaminergic neurodegeneration in striatum. It had been established that the direct administration of $BH_4$ into neuron would induce the neuronal toxicity in vitro. To elucidate a role of $BH_4$ in pathogenesis in the PD in vivo, we assessed the changes of dopamine (DA) and $BH_4$ at striatum in unilateral intranigral iron infused PD rat model. The ipsistriatal DA and $BH_4$ levels were significantly increased at 0.5 to 1 d and were continually depleting during 2 to 7 d after intranigral iron infusion. The turnover rate of $BH_4$ was higher than that of DA in early phase. However, the expression level of GTP-cyclohydrolase I mRNA in striatum was steadily increased after iron administration. These results suggest that the accumulation of intranigral iron leads to generation of oxidative stress which damage to dopaminergic neurons and causes increased release of $BH_4$ in the dopaminergic neuron. The degenerating dopaminergic neurons decrease the synthesis and release of both $BH_4$ and DA in vivo that are relevance to the progression of PD. Based on these data, we propose that the increase of $BH_4$ can deteriorate the disease progression in early phase of PD, and the inhibition of $BH_4$ increase could be a strategy for PD treatment.

• The Journal of Internal Korean Medicine
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• v.20 no.1
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• pp.122-132
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• 1999

Purpose : Hepatitis B virus DNA transfected cell line(HepG2.2.15) was cultured to evaluate the effect of herbs on the expression of HBeAg and the replication of HBV. HepG2.2.15 produces HBV particles as well as viral proteins into cell culture media. Methods : Extracts of herbs were adminitered to the cells on the proper concentration. Culture media was collected 48 hours after the herbal administration and HBeAg level in the media was examined by ELISA method. To confirm that the anti-viral effect was not due to direct cytotocixity of the extracts, normal cell proliferation was shown by cell counting. And as of the interference in protein synthesis of HepG2.2.15 by herb-extracts, we used the result of study that we performed before by ${\alpha}FP$ assay using EIA method. Results& Conclusion : Herb medicines like 地楡(Sanguisorbae Radix) and 覆盆子(Rubi Frusctus) showed significant inhibitory effect on HBeAg expression at p<0.01 and 五味子(Acanthopanacis Cortex) at p<0.05. Whereas, though some herbs such as ?草根(Rubiae Radix), 山査(Crataegii Fructus), 白芍藥(Paeoniae Radix Alba), and 大黃(Rhei Radix et Rhizoma) showed the tendecy to suppress HBeAg. most of them were not significant statistically. From the above, we could conclude that those herb medicines can be applied to patients effectively and further studies on effective fraction of some herbs are thought to be needed.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.281-281
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• 2010

Very low refractive index (<1.4) materials have been proved to be the key factor improving the performance of various optical components, such as reflectors, filters, photonic crystals, LEDs, and solar cell. Highly porous SiO2 are logically designed for ultralow refractive index materials because of the direct relation between porosity and index of refraction. Among them, ordered macroporous SiO2 is of potential material since their theoretically low refractive index ~1.10. However, in the conventional synthesis of ordered macroporous SiO2, the time required for the crystallization of organic nanoparticles, such as polystyrene (PS), from colloidal solution into well ordered template is typical long (several days for 1 cm substrate) due to the low interaction between particles and particle - substrate. In this study, polystyrene - polyacrylic acid (PS-AA) nanoparticles synthesized by miniemulsion polymerization method have hydrophilic polyacrylic acid tails on the surface of particles which increase the interaction between particle and with substrate giving rise to the formation of PS-AA film by simply spin - coating method. Less ordered with controlled thickness films of PS-AA on silicon wafer were successfully fabricated by changing the spinning speed or concentration of colloidal solution, as confirmed by FE-SEM. Based on these template films, a series of macroporous SiO2 films whose thicknesses varied from 300nm to ~1000nm were fabricated either by conventional sol - gel infiltration or gas phase deposition followed by thermal removal of organic template. Formations of SiO2 films consist of interconnected air balls with size ~100 nm were confirmed by FE-SEM and TEM. These highly porous SiO2 show very low refractive indices (<1.18) over a wide range of wavelength (from 200 to 1000nm) as shown by SE measurement. Refraction indices of SiO2 films at 633nm reported here are of ~1.10 which, to our best knowledge, are among the lowest values having been announced.

• Applied Chemistry for Engineering
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• v.1 no.2
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• pp.107-115
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• 1990

New insulin-releasing system on the basis of the redox reaction of glucose was synthesized by immobilizing insulin through a disulfide bond(5, 5'-dithiobis(2-nitrobenzoic acid) to polymer membrane(poly(methyl methacrylate)) and enzyme(glucose oxidase). The disulfide bonds were cleaved upon oxidation of glucose with glucose dehydrogenase and glucose oxidase, releasing insulin from the membrane and enzyme. Sensitivity to glucose concentration was enhanced by coimmobilization of enzyme cofactors(nicotinamide adenin dinucleotide and flavin adenin dinucleotide) acting as electron mediator(for the membrane device), and further enhanced by direct immobilization of insulin on glucose oxidase(for the protein device). Both systems were specific to glucose, and the released insulin was indistinguishable from native insulin. The biological activity of released insulin was 81% of native insulin.

• Journal of Genetic Medicine
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• v.13 no.1
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• pp.41-45
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• 2016

Marfan syndrome (MFS) is an inherited connective tissue disorder with a mutation in the fibrillin-1 (FBN1) gene. Fibrillin is a major building block of microfibrils, which constitute the structural component of the connective tissues. A 10-year-old girl visited our hospital with the chief complaint of precocious puberty. According to her medical history, she had a pulmonary wedge resection for a pneumothorax at 9 years of age. There was no family history of MFS. Mid parental height was 161.5 cm. The patient's height was 162 cm (>97th percentile), and her weight was 40 kg (75th-90th percentile). At the time of initial presentation, her bone age was approximately 11 years. From the ophthalmologic examination, there were no abnormal findings except myopia. There was no wrist sign. At the age of 14 years, she revisited the hospital with the chief complaint of scoliosis. Her height and weight were 170 cm and 50 kg, respectively, and she had arachnodactyly and wrist sign. We performed an echocardiograph and a test for the FBN1 gene mutation with direct sequencing of 65 coding exons, suspecting MFS. There were no cardiac abnormalities including mitral valve prolapse. A cytosine residue deletion in exon 7 (c.660delC) was detected. This is a novel mutation causing a frameshift in protein synthesis and predicted to create a premature stop codon. We report the case of a patient with MFS with a novel FBN1 gene missense mutation and a history of pneumothorax at a young age without cardiac abnormalities during her teenage years.

• Membrane Journal
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• v.18 no.3
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• pp.250-255
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• 2008

Zeolite A have been known to be chemically, mechanically and thermally quite stable. The ion-exchanged membranes were tested for the removal of water from ethanol/water mixtures by pervaporation. Since it is quite difficult to prepare the potassium form of zeolite A by a direct synthesis, it was obtained by the ion-exchange method from NaA zeolite. The effects of concentration of ethanol at the feed side and the temperature were studied on the permeation flux and the separation factor of water. After $Na^+$ ion was exchanged to $K^+$ ion, it was found that the total flux decreased and the separation factor increased.

• Biomolecules & Therapeutics
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• v.26 no.2
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• pp.139-145
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• 2018

The present study was undertaken to investigate the influence of hypothermia on endothelium-independent vascular smooth muscle contractility and to determine the mechanism underlying the relaxation. Denuded aortic rings from male rats were used and isometric contractions were recorded and combined with molecular experiments. Hypothermia significantly inhibited fluoride-, thromboxane $A_{2-}$, phenylephrine-, and phorbol ester-induced vascular contractions regardless of endothelial nitric oxide synthesis, suggesting that another pathway had a direct effect on vascular smooth muscle. Hypothermia significantly inhibited the fluoride-induced increase in pMYPT1 level and phorbol ester-induced increase in pERK1/2 level, suggesting inhibition of Rho-kinase and MEK activity and subsequent phosphorylation of MYPT1 and ERK1/2. These results suggest that the relaxing effect of moderate hypothermia on agonist-induced vascular contraction regardless of endothelial function involves inhibition of Rho-kinase and MEK activities.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.97-97
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• 2011

산화아연 (ZnO)은 넓은 에너지 밴드갭 (~3.37 eV), 큰 엑시톤 결합 에너지 (~60 meV) 그리고 높은 전자 이동도 (bulk~300 $cm^2Vs^{-1}$, single nanowire~1000 $cm^2Vs^{-1}$)를 갖고 있어, 광전자 소자 및 반도체소자 응용에 매우 널리 사용되고 있다. 특히, 산화아연 나노로드(ZnO nanorod)는 1차원 나노구조로써 더욱 향상된 전자 이동도와 캐리어의 direct path way를 제공하여 차세대 광전자소자 및 태양광 소자의 응용에 대한 연구가 매우 활발하게 이루어지고 있다. 한편, 이러한 산화아연 나노로드를 성장시키기 위하여 VLS (vapor-liquid-solid), 졸-겔 공정(sol-gel process), 수열합성(hydrothermal synthesis), 전기증착(electrodeposition)등 다양한 방법이 보고되었지만, 이러한 산화아연 나노로드의 성장방법은 실제적인 소자응용을 위한 패터닝 형성에 대하여 제약을 받는 문제점이 있다. 이들 중에서 수열합성법과 전극증착법은 ZnO 또는 AZO (Al doped ZnO) seed 층 표면과 성장용액의 화학반응에 의해서 선택적으로 산화아연 나노로드를 성장시킬 수 있다. 이에 본 연구에서는, 광전자소자의 응용을 위한 간단한 패터닝 공정을 위해, 산화인듐주석(ITO) 박막이 증착된 유리기판(glass substrate)위에 수열합성법과 전극증착법을 이용하여 산화아연 나노로드를 선택적으로 성장시켰다. 실험을 위해, ITO glass 위에 RF magnetron 스퍼터를 사용하여 AZO seed 층을 metal shadow mask를 이용하여 패터닝을 형성한 후, 질산아연과 헥사메틸렌테트라아민으로 혼합된 용액에 $85^{\circ}C$ 온도를 유지하여, 패터닝이 형성된 샘플에 전압을 인가하여 성장시켰다. 나노구조 분석을 위해, 전계주사현미경을 이용하여 수열합성법과 전기증착법에 의한 패터닝된 산화아연 나노로드를 비교하여 관찰하였다.