• 대한소아치과학회지
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• 제27권2호
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• pp.274-282
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• 2000

소아의 유구치 수복에 흔히 사용하는 stainless steel crown은 주성분으로 $70\sim90%$의 니켈과 $5\sim15%$의 크롬을 함유하고 있다. 이 중 니켈 자체가 일으킬 수 있는 allergy반응이나 발암성등의 부작용이 성인에서는 활발하게 연구되고 있으며, 특히 니켈이 포함된 합금을 이용한 보철물 주변에 병원성이 있는 니켈내성 Enterococci가 존재한다는 보고가 있어 성인과는 구강환경이 다른 소아에서도 stainless steel crown 주변에 니켈내성균주가 존재하는지를 확인하고자 이 실험을 시행하였다. 유구치에 stainless steel crown(Anatom primary crown, Sankin)을 6개월 이상 장착한 환자 15명과 유구치 협면에 치아우식증이 없는 환자 15명의 치은열구액에서 채취한 시료를 BHI 한천배지, 니켈배지 및 Bile-esculin azide(BEA) 한천 배지에 도말하였다. BEA한천배지에서 자란 enterococci를 니켈내성정도를 확인하기위해 3, 5, 10, 30, 50mM 니켈배지에 접종한후 성장상태를 관찰하였다. 실험군에서는 BHI 한천배지에서 507,350개의 균주가 분리되었으며, 이 중 니켈내성세균(3mM)은 53,864 균주였다. 대조군에서는 BHI 한천배지에서 414,590 균주가, 니켈내성세균(3mM)은 37,523 균주가 분리되었다. BEA한천배지에서는 실험군의 경우 95개가 분리되었으며, 대조군에서는 20개의 균주만이 분리되었다. BHI 한천배지에서 분리된 총 균주 수를 100으로 놓았을 때 3mM 니켈배지에서 분리된 균주는 실험군에서는 10.62%, 대조군에서는 9.05%를 차지하여 두 군간에 뚜렷한 차이는 없었으며, 3mM 니켈배지에서 자란 총 균주 수와 BEA 한천배지에서 배양된 enterococci를 3mM 니켈배지로 옮겨 배양했을 때와 비교하면, 실험군에서 0.13%, 대조군에서 0.03%로 모두 1%이하의 분포를 차지하였다.

• Journal of Photoscience
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• 제3권2호
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• pp.77-83
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• 1996

Photosensitization via the singlet oxygen ($^1O_2$) mechanism by the binuclear iron-sulfur center, denoted as [2Fe-2S], was investigated, using a highly purified ferredoxin (Fd) preparation from spinach leaves. Since the apoprotein of Fd contains a good number of amino acid residues that are readily reactive with $^1O_2$ and thus interfere with the detection of $^1O_2$ generated from [2Fe-2S], we attempted to deprive the $^1O_2$-sensitive residues of their $^1O_2$-scavenging capacity as much as possible by treating Fd with rose bengal plus 550 nm monochromatic light and thereby photooxidatively degrading these residues. The photochemically modified Fd was found to keep the structural integrity of its Fe-S group virtually unaffected by the treatment. By employing chemical trap method for measurement and examining the kinetic effects of azide and deuterium oxide on the reactions of $^1O_2$ with various trap compounds, we were able to demonstrate that [2Fe-2S] indeed acts as a photosensitizer via $^1O_2$. Further, the minimum quantum yield of $^1O_2$ production by [2Fe-2S] was estimated to be 0.0047.

• 통합자연과학논문집
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• 제7권4호
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• pp.266-272
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• 2014

Oxocane high explosives substituted to explosive group such as azide (-CH2N3), nitrate (-CH2ONO2), and hydrazine (-CH2N2H3) are investigated theoretically the acid catalyzed reaction using the semiempirical MINDO/3, MNDO and AM1 methods to use as the guidelines of high explosives. The nucleophilicity and basicity of oxocane high explosives can be explained by the value of negative charge on oxygen atom of oxocane and the reactivity in propagation step can be represented by the value of positive charge on carbon atom and low electrophile LUMO energy. It was known that carbenium ion was favorable due to the stable energy (11.745~25.461 Kcal/mol) between oxonium ion and carbenium ion in the process of cyclic oxonium ion of oxocane high explosives being converted to open carbenium ion in oxocane high explosives. The value of concentration of cyclic oxonium ion and open carbenium ion in equilibrium status was found to be a major determinant of mechanism, it was expected to react faster in the prepolymer propagation step in SN1 mechanism than in that of SN2.

• Bulletin of the Korean Chemical Society
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• 제26권12호
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• pp.1946-1952
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• 2005

New group 15 organometallic compounds, M$(phenanthrenyl)_3$ (M = P (1), Sb (2), Bi (3)) have been prepared from the reactions of 9-phenanthrenyllithium with $MCl_3$. A reaction of 9-(diphenylphosphino)phenanthrene with 2,6-diisopropylphenyl azide led to the formation of (phenanthrenyl)${(Ph)}_2P$=N-(2,6-$^iPr_2C_6H_3$) (4). The crystal structures of 2 and 4 have been determined by single-crystal X-ray diffractions, both of which crystallize with two independent molecules in the asymmetric unit. Compound 2 shows a trigonal pyramidal geometry around the Sb atom with three phenanthrenyl groups being located in a screw-like fashion with an approximately $C_3$ symmetry. A significant amount of CH- -$\pi$ interaction exists between two independent molecules of 4. The phosphorus center possesses a distorted tetrahedral environment with P-N bond lengths of 1.557(3)$\AA$ (P(1) N) and 1.532(3)$\AA$ (P(2)-N), respectively, which are short enough to support a double bond character. One of the most intriguing structural features of 4 is an unusually diminished bond angle of C-N-P, attributable to the hydrogen bonding of N(1)-H(5A) [ca. 2.49$\AA$ between two adjacent molecules in crystal packing. The compounds 1-3 show purple emission both in solution and as films at room temperature with emission maxima ($\lambda_{max}$) at 349, 366, and 386 nm, respectively, attributable to the ligand centered $\pi$ $\rightarrow$ $\pi^\ast$ transition in phenanthrene contributed by the lone pair electrons of the Gp 15 elements. Yet the nature of luminescence observed with 4 differs in that it originates from $\pi$ (diisopropylbenzene)-$\pi^\ast$ (phenanthrene) transitions with the $\rho\pi$contribution from the nitrogen atom. The emission maximum of 4 is red-shifted ranging 350-450 nm due to the internal charge transfer from the phenanthrenyl ring to the N-arylamine group as deduced from the ab initio calculations.

• 분석과학
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• 제18권5호
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• pp.391-395
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• 2005

$[Cd(N_3)_2(2-ethylimidazole)_2]$ 착물을 합성하고 단결정 X-선 회절법으로 구조를 규명하였다. 이 착물은 단사정계, 공간군 Cc, a=16.200(3), b=12.926(3), $c=7.007(1){\AA}$, ${\beta}=102.29(3)^{\circ}$, $V=1433.7(5){\AA}^3$, Z=4로 결정화되었으며, 1874 개의 독립적인 회절반점에 대한 최종 신뢰도 인자 $R_1$ 및 ${\omega}R_2$ 값은 각각 0.0239 및 0.0604 이었다. Cd(II) 금속 원자는 4개의 azido 리간드와 2개의 2-ethylimidazole 리간드의 질소 원자가 배위되어 약간 찌그러진 팔면체 구조를 나타낸다. c 축 방향으로 배열되어 있는 Cd(II) 금속 원자 사이를 azido 리간드가 end-on (${\mu}-1$,1) 형태로 bridge 하고 2-ethylimidazole 리간드가 시스 형태로 결합하여 이 착물은 1차원의 zigzag 사슬 구조를 형성한다.

• 자연과학논문집
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• 제7권
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• pp.47-51
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• 1995

입체 이성질체를 합성하는 방법으로 최근에 알려진 입체선택성 촉매를 이용한 유기반응을 연구 하기 위하여 비천연 아미노산인 인돌린-2- 카르본산으로 부터카르본산그룹의 환원,2차아민기의 보호화,메실화,아지도치환,환원에 의한 아민기로의 전환, 술폰화, 보호기제거등의 총 5단계의 합성과정을 거쳐 목적하는 술폰아미드를 합성하였다. 각 생성물은 관 크로마토그래피에 의하여 분리 정제후 핵자기공명스펙트럼($^1H,^13C $ NMR) 적외선 스펙트럼 등에 의하여 구조를 확인 하였다.

• 대한본초학회지
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• 제25권2호
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• pp.137-144
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• 2010

Objectives : We investigated genetic toxicity of HMCO5 using the Micronucleus Test in bone marrow cells of mice and Bacterial Reverse Mutation Assay in plate incorporation method according to OECD Guidelines and KFDA Guidelines. Methods : 1. Micronucleus test: The male rats were divided into 5 groups, respectively; G(1), treated with distilled water: G(2), treated with 1250mg/kg HMC05: G(3), treated with 2500mg/kg HMC05, G(4), treated with 5,000mg/kg HMC05; G(5), treated with Cyclophosphamide $H_2O$. Sterilized distilled water and HMC05 were administered for two consecutive days. Cyclophosphamide $H_2O$ was administered once on the day of 2nd administration. 2. Bacterial Reverse Mutation Aassay: Experimental groups were divided into two groups: with S-9mix(+S) or without S-9mix(-S). Each group treated with sterilized distilled water only, HMCO5(62, 185, 556, 1,667, $5,000{\mu}g$/plate) and, positive vehicles(Sodium azide, 2-Aminoanthracene, 4-Nitroquinoline N-oxide, ICR 191), respectively. Results : HMC05 did not show any changes in the number of micronucleated polychromatic erythrocytes(MNPCE) among 200 polychromatic erythrocytes compare to negative control. However, there were significant (p<0.01) increase with CPA in MNPCE. In Bacterial Reverse Mutation Aassay, no significant increases in the number of revertant colonies compared to (삭제) negative control were detected in all concentrations of HMC05. Conclusions : These results indicate that HMC05 did not show any genotoxicity against in Micronucleus test and Bacterial Reverse Mutation Aassay.

• Bulletin of the Korean Chemical Society
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• 제33권7호
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• pp.2213-2218
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• 2012

Efficient synthetic routes were developed to prepare a sizable amount (4-15 grams) of the chiral epoxides 4-6 as versatile intermediates for the synthesis of aspartyl protease inhibitors of therapeutic interest such as HIV protease and ${\beta}$-secretase. Oxidative cleavage of the C(2)-C(3) double bond of L-ascorbic acid followed by functional group manipulation led to the preparation of the epoxide 10, which was opened with an azide to yield a common aziridine intermediate 12. Through opening of the aziridine ring of 12 with either a carbon or a sulfur nucleophile, chiral epoxide precursors 4-6 could be prepared for various HIV protease inhibitors. Except for the final low melting epoxides 5 and 6, all intermediates were obtained as crystalline solids, thus the synthetic pathway can be easily applied to a large-scale synthesis of the chiral epoxides.

• The Plant Pathology Journal
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• 제21권4호
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• pp.301-309
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• 2005

Trichoderma species/isolates exhibited varied degree of agglutination on sclerotial (Sc) and hyphal (Hy) surface of Macrophomina phaseolina. The agglutination efficiencies on Sc and Hy ranged from $11\;to\;57\%$. Isolates of T. harzianum (Th) and T. viride (Tv) showed greater agglutination on Sc ($23-57\%$) and Hy ($16-47\%$). Different enzymes (trypsin, pepsin, proteinase k, a-chymotrypsin, lyticase and glucosidase) and inhibitors (tunicamycin, cycloheximide, brefeldin A, sodium azide, dithiothreitol and SDS) reduced the agglutination potential of conidia of Th-23/98 and Tv-25/98; however, the extent of response varied greatly in different treatments. Different fractions of Th-23/98 and Tv-25/98 exhibited haemagglutinating reaction with human blood group A, B, AB and O. Haemagglutinating activity was inhibited by different sugars and glycoproteins tested. Crude haemagglutinating protein from outer cell wall protein fraction of Th-23/98 and Tv-25/98 were eluted on Sephadex G-100 column. Initially Th-23/98 and Tv-25/98 exhibited two peaks showing no agglutination activity; however, lectin activity was detected in the third peak. Similar to crude lectin, the purified lectin also exhibited haemagglutinating activity with different erythrocyte source. SDS-PAGE analysis of partially purified lectin revealed single band with an estimated molecular mass of 55 and 52 kDa in Th-23/98 and Tv-25/98, respectively. Trypsin, chymotrypsin and b-1,3-glucanase totally inhibited lectin activity. Similarly, various pH also affected the haemagglutinating activity of Th-23/98 and Tv-25/98. From the present observations, it can be concluded that the recognition/attachment of mycoparasite (T. harzianum and T. viride) to the host surface (M. phaseolina) may be most likely due to lectin-carbohydrate interaction.

• 대한화학회지
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• 제5권1호
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• pp.33-37
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• 1961

We have shown that carboxy-peptidase destroys the biological activity of angiotensin octa-and deca-peptides. Since Proline occurs as the seventh amino acid from the amino end of the chain and since carboxypeptidase does not cleave proline from a peptid chain, it is evident that the heptapeptid H.asp-arg-val-tyr-ileu-his-pro.OH is formed by this hydrolysis. This peptide must then be biologically inactive. In order to determine whether the phenyl group of the C-terminal amino acid was the necessary requirement for biological activity of the octapeptide, $ala^8$ angiotensin octapeptide(amino acids of peptides numbered from amino end) was synthesized. For this synthesis the four dipeptides were prepared: carbobenzoxy-L-prolyl-L-alanine-P-nitrobenzyl-ester, m.p. $134-135^{\circ}C,$ carbobenzoxy-L-isoleucyl-imidazole benzyl-L-histidine methyl ester, m.p. $114-116^{\circ}C,$ carbobenzoxy-L-valyl-L-tyrosine hydrazide and carbobenzoxy B-benzyl-L-aspartyl-nitro-L-arginine. The first three dipeptides were obtained as crystalline compounds. Imidazole-benzyl-L-histidine was used in the hope that it would block the histidine imidazole against side reactions in steps subsequent to the formation of the C-terminal tetrapeptide. Also, it was through that the imidazole benzylated peptides would be easier to crystallize. This, however, was not the case. The tetrapeptide, carbobenzoxy-L-isoleucyl-L-im, benzyl-histidyl, L-prolyl-L-alanine-nitrobenzyl ester was not obtained in a crystalline form. Neither could the mono-or dihydrobromide of the tetrapeptide free base be induced to crystallize. Carbobenzoxy-L-valyl-L-tyrosine azide was condensed with the tetrapeptide free base to yield the protected hexapeptide; carbobenzoxy-L-valyl-L-tyrosyl-L-isoleucyl-L-im, benzyl, histidyl-L-Prolyl-L-alanine-nitrobenzyl ester. Upon removal of the carbobenzoxy group with hydrogen bromide in acetic acid an amorphous free base hexapeptide ester was obtained. This compound gave the correct C, H, N analysis and contained the six amino acids in the correct ratio. The octapeptide was obtained by condensing this hexapeptide with carbobenzoxy-B-benzyl-L-aspartyl-nitro, L-arginine using the mixed anhydride method of condensation. This amorphous product was proven to be homogenous by chromatography in two solvent systems and upon hydrolysis yielded the eight amino acids in correct ratio. The five protecting groups were removed from the octapeptide by hydrogenolysis over palladium black catalyst. Biological assay of the free peptide indicated that it possessed less than 0.1 per cent of both pressor and oxytocic activity of the phenylalanine8 angiotensin. This suggests that the phenyl group is a point of attachment between angiotensin and its biological receptor site.