• Bulletin of the Korean Chemical Society
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• 제31권2호
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• pp.303-308
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• 2010

Pseudo-first-order rate constants ($k_{obsd}$) have been measured spectrophotometrically for nucleophilic substitution reactions of 4-nitrophenyl benzoate (5a), 4-nitrophenyl 4-methoxybenzoate (5b), and 4-nitrophenyl 4-hydroxybenzoate (5c) with alkali metal ethoxides, $EtO^-M^+$ ($M^+=Li^+$, $Na^+$ and $K^+$) in anhydrous ethanol (EtOH) at $25.0{\pm}0.1^{\circ}C$. The plots of $k_{obsd}$ vs. [$EtO^-M^+$] exhibit upward curvatures in all cases, indicating that $M^+$ ions catalyze the reactions and ionpaired $EtO^-M^+$ species are more reactive than dissociated $EtO^-$. Second-order rate constants for reactions with dissociated $EtO^-$ and ion-paired $EtO^-M^+$ (i.e., $k_{EtO^-}$ and $k_{EtO^-M^+}$, respectively) have been calculated from ion-pair treatment for the reactions of 5a and 5b. However, such ion-pair treatment has failed to determine $k_{EtO^-}$ and $k_{EtO^-M^+}$ values for the reactions of 5c. It has been concluded that reactions of 5a and 5b are catalyzed by one metal ion, which increases electrophilicity of the reaction center through coordination on the carbonyl oxygen. In contrast, reactions of 5c have been suggested to involve two metal ions, i.e., the one coordinated on the carbonyl oxygen increases the electrophilicity of the reaction center while the other one associated on the phenoxy oxygen decreases the charge repulsion between the anionic reagents (i.e., $EtO^-$ and deprotonated 5c). It has been found that the rate equation derived from the mechanism involving two metal ions fits nicely to the kinetic results obtained for the reactions of 5c.

• Journal of Korean Neurosurgical Society
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• 제29권2호
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• pp.188-195
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• 2000

Objective : Essential tremor(ET) is the most common movement disorder, however, there has been little agreement in the neurologic literature regarding diagnostic criteria for ET. Familial ET is an autosomal dominant disorder presenting as an isolated postural tremor. The main feature of ET is postural tremor of the arms with later involvement of the head, voice, or legs. In previous studies, it was reported that ET susceptibility was inherited in an autosomal dominant inheritance. As previous results, it would suggest that ET might be associated with defect of mitochondrial or nuclear DNA. Recent studies are focusing on molecular genetic detection of movement disorders, such as essential tremor and restless legs syndrome. Moreover, authors have analysed mitochondrial DNA(mtDNA) from the blood cell of positive control(PC) and ET patients via long and accurate polymerase chain reaction(LA PCR). Materials & Methods : Blood samples were collected from PC and 9 ET patients. Total DNA was extracted twice with phenol followed by chloroform : isoamylalcohol. For the analysis of mtDNA, LA PCR was performed by mitochondrial specific primers. Results : With this technique, deletions of large quantities were detected within several regions of mtDNA in ET patients except for D-loop and CO I regions. Conclusion : The authors believe that ET is a genentic disorder with deficiency of mitochondrial DNA multicomplexes and mitochondiral dysfunction could be one of major causative factors of ET. Mitochondrial dysfunction may play an important role in the pathogenesis and possibility of disease progression among familial group with ET patients.

• 복식
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• 제19권
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• pp.175-194
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• 1992

Le Proche-Orient est le pays de la Bible, Le peuple He breu ancien, appartenant la race des S mits s mi-nomades, est venu avec Abraham, de m sopotamie en Palestine, terre de Canaan. Nous avons consid r les v tements du peuple des anciens H breux en nous basant sur la Bible et en observant des peintures murales et des bas-reliefs des divers payes de l'ancienne poque, Pour comprendre l' volution des v tements des gens de la pr sente r gion palestinienne, nous avons tudi les v tements traditionnels de la race b douine qui m nent jusqu' maintenant une vie nomade dans le m nent jusqu' maintenant une vie nomade dans le d sert, parce que nous n'avons pas pu connaitre le processus d' volution des v tements apr s l'ancienne poque la suite d' v nements historiques compliques. En conclusion, nous pouvons nous r sumer comme suit: 1) Nous pensons que la kimlah, costume important du peuple h breu ancien est devenu abajeh, manteau des B douins, puisque ces v tements servent prot ger le corps lors des changments de temps, et la nuit on les utilise comme couverture et comme sac pour y mettre des objets, et comme tente lors su travail. en un mot, les fonctions de la Simlah et celles de l'abajeh sont les memes l' poque ancienne et maintenant. 2) Nous pensons que la forme et l'utilisation de la Kethoneth ayant une forme de tunique et de la thob des B douins sont presque semblable. La kethoneth et la thob sont la tuniqu importante que portent jusqu' maintenant tous les peuples du Proche-Orient. 3) Comme on le voit dans la Bible, les femmes du peuple h breu et celles des B douins utilisent le voile pour couvrir la e te, et se servent d'accessoires pour d corer leur corps. A l'avenir, les vVtements des Palestiniens, dans une recherche pous approfondie, feront l'objet de a 2 me partie de l' tude des costumes du Proche-Orient.

• Journal of Oral Medicine and Pain
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• 제26권4호
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• pp.319-329
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• 2001

Endothelin-1 (ET-1) is a recently discovered potent vasoconstrictive peptide. It was first identified in vascular endothelial cells. ET-1 is a 21-amino acid peptide and elicits systemic effects such as stimulation of the production of atrial natriuretic peptide and release of aldosterone and corticosterone. In this study, to examine the role of ET-1 in the bone metabolism, effect of ET-1 on the proliferation and activity of osteoblastic cells was studied using HOS cells as osteoblast model. ET-1 dose-dependently increased the cell proliferation as determined by cell counting and MTT reduction assay after 48hr treatment. Alkaline phosphatase activity was inhibited by ET-1 and showed significant inhibition by 50 and 100 nM ET-1. ET-1 increased NBT reduction by HOS cells dose-dependently showing that ET-1 may increase the superoxide production by osteoblasts. Nitrite concentration in the media of HOS cell culture without cytokine stimulation was negligible and unaffected by ET-1 after 48hr treatment. Finally, after collection and concentration of conditioned media, gelatinase activity produced by HOS cells was determined by zymography. HOS cells can produce and secrete the gelatinase (gelatinase A type as determined by molecular weight of about 65,000) into culture media, however, ET-1 had no effect on the gelatinase activity. These findings suggest that ET-1 may have diverse effects on the proliferation and differentiation of osteoblasts, therefore, it may play an important role in bone metabolism.

• Natural Product Sciences
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• 제20권3호
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• pp.216-225
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• 2014

The present study was designed to investigate whether ethylacetate (EtOAc) fraction extracted from Rubus coreanum affect the contractility of the isolated thoracic aortic strips and blood pressure of normotensive rats. The EtOAc fraction ($400{\mu}g/mL$) significantly depressed both phenylephrine (PE, $10{\mu}M$)- and high $K^+$ (56 mM)-induced contractile responses of the isolated thoracic aortic strips in a concentration-dependent fashion. In the simultaneous presence of L-NAME (an inhibitor of NO synthase, $300{\mu}M$) and EtOAc ($400{\mu}g/mL$), both PE- and high $K^+$-induced contractile responses were recovered to the corresponding control level in comparison with inhibition of EtOAc-treatment alone. Moreover, in the simultaneous presence of EtOAc after pretreatment with 0.4% CHAPS, both PE- and high $K^+$-induced contractile responses were recovered to the corresponding control level compared to the inhibitory response of EtOAc-treatment alone. Also, in anesthetized rats, EtOAc fraction (0.3~3.0 mg/kg) injected into a femoral vein dose-dependently produced depressor responses. This hypotensive action of EtOAc fraction was greatly inhibited after treatment with phentolamine (1 mg/kg), chlorisondamine (1 mg/kg), L-NAME (3 mg/kg/30 min) or sodium nitroprusside ($30{\mu}g/kg/30 min$). Intravenous infusion of EtOAc fraction (1.0~10.0 mg/kg/30 min) markedly inhibited norepinehrine-induced pressor responses. Taken together, these results demostrate that EtOAc causes vascular relaxation in the isolated rat thoracic aortic strips as well as hypotensive action in anesthetized rats. These vasorelaxation and hypotension of EtOAc seem to be mediated at least by the increased NO production through the activation of NO synthase of vascular endothelium, and the inhibitory adrenergic modulation.

• Bulletin of the Korean Chemical Society
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• 제35권1호
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• pp.177-181
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• 2014

Pseudo-first-order rate constants ($k_{obsd}$) have been measured spectrophotometrically for the reactions of Y-substituted-phenyl benzoates (5a-j) with potassium ethoxide (EtOK) in anhydrous ethanol at $25.0{\pm}0.1^{\circ}C$. The plots of $k_{obsd}$ vs. [EtOK] curve upward regardless of the electronic nature of the substituent Y in the leaving group. Dissection of $k_{obsd}$ into the second-order rate constants for the reactions with the dissociated $EtO^-$ and ion-paired EtOK (i.e., $k_{EtO^-}$ and $k_{EtOK}$, respectively) has revealed that the ion-paired EtOK is more reactive than the dissociated $EtO^-$. The Br${\phi}$nsted-type plots for the reactions with the dissociated $EtO^-$ and ion-paired EtOK exhibit highly scattered points with ${\beta}_{lg}$ = -$0.5{\pm}0.1$. The Hammett plots correlated with ${\sigma}^o$ constants result in excellent linear correlations, indicating that no negative charge develops on the O atom of the leaving Y-substituted-phenoxide ion in transition state. Thus, it has been concluded that the reactions with the dissociated $EtO^-$ and ion-paired EtOK proceed through a stepwise mechanism, in which departure of the leaving group occurs after the RDS, and that $K^+$ ion catalyzes the reactions by increasing the electrophilicity of the reaction center through a four-membered cyclic TS structure.

• Bulletin of the Korean Chemical Society
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• 제31권12호
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• pp.3543-3548
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• 2010

A kinetic study on nucleophilic displacement reactions of 2-pyridyl X-substituted benzoates 1a-e with potassium ethoxide (EtOK) in anhydrous ethanol is reported. Plots of pseudo-first-order rate constants ($k_{obsd}$) vs. $[EtOK]_o$ exhibit upward curvature. The $k_{obsd}$ value at a fixed $[EtOK]_o$ decreases steeply upon addition of 18-crown-6-ether (18C6) to the reaction mixture up to [18C6]/$[EtOK]_o$ = 1 and then remains nearly constant thereafter. In contrast, $k_{obsd}$ increases sharply upon addition of LiSCN or KSCN. Dissection of $k_{obsd}$ into $k_{EtO^-}$ and $k_{EtOM}$ has revealed that ion-paired EtOK is more reactive than dissociated $EtO^-$, indicating that $K^+$ ion acts as a Lewis acid catalyst. Hammett plots for the reactions of 1a-e with dissociated $EtO^-$ and ion-paired EtOK result in excellent linear correlation with $\rho$ values of 3.01 and 2.67, respectively. The $k_{EtOK}/k_{EtO^-}$ ratio increases as the substituent X in the benzoyl moiety becomes a stronger electron-donating group. $K^+$ ion has been concluded to catalyze the current reaction by stabilizing the transition state through formation of a 6-membered cyclic complex.

• Bulletin of the Korean Chemical Society
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• 제34권5호
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• pp.1525-1529
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• 2013

Pseudo-first-order rate constants ($k_{obsd}$) have been measured spectrophotometrically for the nucleophilic substitution reactions of 2-pyridyl thionobenzoate (5b) with alkali-metal ethoxides (EtOM, $M^+=Li^+$, $Na^+$, $K^+$, and 18-crown-6-ether complexed $K^+$) in anhydrous ethanol at $25.0{\pm}0.1^{\circ}C$. The plots of $k_{obsd}$ vs. $[EtOM]_o$ curve upward regardless of the nature of the $M^+$ ions, while those of $k_{obsd}/[EtO^-]_{eq}$ vs. $[EtO^-]_{eq}$ are linear with a positive intercept. Dissection of $k_{obsd}$ into $k_{EtO^-}$ and $k_{EtOM}$ (i.e., the second-order rate constants for the reactions with the dissociated $EtO^-$ and ion-paired EtOM, respectively) has revealed that the ion-paired EtOM is more reactive than the dissociated $EtO^-$, and $M^+$ ions catalyze the reactions in the order $K^+$ < $Na^+$ < $Li^+$ < 18C6-complexed $K^+$. The plot of log $k_{EtOM}$ vs. $1/r_{Stokes}$ results in an excellent linear correlation, indicating that the reactions are catalyzed by the solvated $M^+$ ions but not by the bare $M^+$ ions. The reactions of 5b with EtOM have been concluded to proceed through a six-membered cyclic TS, in which the solvated $M^+$ ions increase the electrophilicity of the reaction center and the nucleofugality of the leaving group.

• Tuberculosis and Respiratory Diseases
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• 제48권2호
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• pp.210-222
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• 2000

한국산 잡견 11마리를 대상으로 자가 혈병을 이용한 급성 폐색전증을 만들고 ET 수용체 길항제를 투여하여 다음과 같은 결과를 얻었다. 1. 혈병 투여후 폐동맥압은 상승하였고 심박출량은 감소하였으며 페혈관 저항은 증가하였다. 동맥혈 산소분압과 혼합 정맥혈의 산소 분압이 감소하였고 사강호흡이 증가하였고 생리적 단락이 증가하였으나 전신혈압은 변동이 없었다. 모든 측정치는 수용체 길항제 투여군과 대조군간에 차이를 보이지 않았다. 2. ET-1 수용체 길항제 투여후 전신혈압, 동맥 및 혼합정맥혈산소 분압, 동정맥 단락, 및 사강호흡의 정도는 두군간에 차이를 보이지 않았으나, 폐동맥압, 심박출량, 폐혈관 저항은 길항제 투여 30분후부터 수용체 길항제 투여군과 대조군간에 차이를 보이기 시작하여 210분후까지 지속되었다. 3. ET-1의 농도는 색전전(Baseline)에 비하여 색전후 동맥혈, 혼합정맥혈, 및 그 비(동맥혈/혼합정맥혈)가 증가를 보였고, 수용체 길항제 투여후 투여군에서는 대조군에 비해 ET-1의 농도 증가가 의미 있게 높았다. 4. 면역조직화학염색상에서 폐색전증이 유발된 개의 폐혈관 및 폐조직에서 색전을 투여하지 않은 정상 개의 조직에 비해 ET-1의 발현이 증가되었다. 5. Northern blot 상에서 폐색전이 일어난 폐조직의 preproET-1 mRNA 발현은 색전이 일어나지 않은 개의 폐조직에 비하여 증가되었다.

• 조형예술학연구
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• 제3권
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• pp.33-61
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• 2001

Dans les arts modernes, nous ressentons souvent un $probl\`{e}me$ $disloqu\'{e}par$ rapport aux humains. Ceci ne viendrait-il pas $peut-\^{e}tre$ do notre $pens\'{e}e$ dans l' $\'{e}change$ culturelle entre le monde et nous qui s' appuie trop une $temporalit\'{e}$ et logique? Cette $the\`{s}e$ approche ce $probl\`{e}me$ $\`{a}$ travers one perception anthropologique do monde, en $\'{e}tudiant$ les arts tridimensionnels avec ses $\'{e}schelles$ qui deviennes plus on plus agrandis. Maurice Merleau-Ponty, dans son livre 'la $ph\'{e}nom\'{e}nologie$ de la perception', bien $r\'{e}sumait$ une $intersubjectivit\'{e}$ entre l' espace et nous. Selon lui, l' homme prend conscience do la forme des objets avec son environnement parce quil est un corps on interaction avec eux. Donc nous $r\'{e}f\'{e}rons$ ce livre pour notre set. Et on essayera ici d' $\'{e}tudier$ le travail do Constantin Brancusi, de Alberto Giacometti, do Richard Serra et do quelques d' autres travaux d' artistes L' oeuvre do Brancusi 'la Colonne sans fin', la taille plus de 29 m, produit one impression sur le spectateur relativement $\grave{a}$ la forme continue et $r\'{e}p\'{e}t\'{e}e$ $\`{a}$ linfini de $mani\'{e}re$ unifome. La pratique de Giacometti qui tenait compte do son envergure et de la longueur do son corps ainsi que do distance et de la mesure do sos bras, Il $d\'{e}formait$ aussi les silhouettes et transformait les objects en les $\'{e}tirant$ dans la perspective. Rosalind Krauss parler $\`{a}$ loeuvre do Serra, dans son livre 'l' originalit de lavant-garde et sutres mythes modernistes' (pp. 319-333), le spectateur est toujours on mouvement on liaison entre l' horizon do corps et celui do monde. Cette $transitivit\'{e}$ abstraite $r\'{e}ciproque$ entre le regardeur et le $regard\'{e}$, qui est comme le sujet de nombreuses oeuvres do Serra. Cependant le Maximalisme est $\`{a}$ l' origine Minimalisme qui s' $\'{e}tend$ dans ses efforts $th\'{e}oriques$ jusqu' au l' espace architecturale. Ces sculptures do grandes dimensions so situent autour de $b\^{a}timent$ ou dans lespace environnementale, comme ils sent l' architecture et le paysage. On suppose ici, leurs concepts de l' espace $\'{e}largit$ $\`{a}$ celui d' architecture. La sculpture et l' architecture $r\'{e}ciproque$ l' espace tridimensionnel entre eux, mais selon l' argument do Herbert Read pour la distinction de ces deux arts originaux sont, deux saisies de l' espace, ici englobant, $l\`{a}$ $englob\'{e}$. On $\'{e}tudie$ dans co set de concept de l' espace et de l' $\'{e}chelle$ d' objet par rapport au corps humain.