• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1994년도 제2회 추계심포지움
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• pp.69-80
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• 1994

Although ureases play important roles in microbial nitrogen metabolism and in the pathogenesis of several human diseases, little is known of the mechanism of metallocenter biosynthesis in this Ni-Containing enzyme. Klebsiella aerogenes urease apo-protein was purified from cells grown in the absence of Ni. The purified apo-enzyme showed the same native molecular weight, charge, and subunit stoichiometry as the holo-enzyme. Chemical modification studies were consistent with histidinyl ligation of Ni. Apo-enzyme could not be activated by simple addition of Ni ions suggesting a requirement for a cellular factor. Deletion analysis showed that four accessory genes (ureD, ureE, ureF, and ureG) are necessary for the functional incorporation of the urease metallocenter. Whereas the $\Delta$ureD, $\Delta$ureF, and $\Delta$ureG mutants are inactive and their ureases lack Ni, the $\Delta$ureE mutants retain partial activity and their ureases possess corresponding lower levels of Ni. UreE and UreG peptides were identified by SDS-polyacrylamide gel comparisons of mutant and wild type cells and by N-terminal sequencing. UreD and UreF peptides, which are synthesized at ve교 low levels, were identified by using in vitro transcription/translation methods. Cotransformation of E. coli cells with the complementing plasmids confirmed that ureD and ureF gene products act in trans. UreE was purified and characterized. immunogold electron microscopic studies were used to localize UreE to the cytoplasm. Equilibrium dialysis studies of purified UreE with $^{63}$ NiC1$_2$ showed that it binds ～6 Ni in a specific manner with a $K_{d}$ of 9.6 $\pm$1.3 $\mu$M. Results from spectroscopic studies demonstrated that Ni ions are ligated by 5 histidinyl residues and a sixth N or O atom, consistent with participation of the polyhistidine tail at the carboxyl termini of the dimeric UreE in Ni binding. With these results and other known features of the urease-related gene products, a model for urease metallocenter biosynthesis is proposed in which UreE binds Ni and acts as a Ni donor to the urease apo-protein while UreG binds ATP and couples its Hydrolysis to the Ni incorporation process.ouples its Hydrolysis to the Ni incorporation process.s.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제33권3호
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• pp.247-255
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• 2007

The bone morphogenic protein(BMP) can promote migration and growth of mesenchymal cells and initiate process for bone and cartilage formation. Cartilage-derived morphogenic protein(CDMP)-1 and -2 belong to the bone morphogenetic protein family in the transforming growth factor(TGF)-${\beta}$ superfamily. Although pleomorphic adenoma of the salivary glands is an epithelial tumor, it frequently shows ectopic cartilaginous formation with biomolecular studies. The mechanism of pathogenesis in cartilaginous formation is still controversy. We examined the expression and localization of CDMP-1 and -2, in comparison with the localization of cartilaginous matrix proteins, in human normal salivary glands and 20 cases of pleomorphic adenoma using immunohistochemical methods. The results were followed. 1. CMP-1 was immunolocalized in the striated ducts and the intercalated ducts, but not expressed in excretory duct, CDMP-2 was not expressed in the normal salivary glands. 2. CMP-1 was immunolocalized in the ductal cell and cuboidal neoplastic myoepithelial cells around the chondroid areas of the pleomorphic adenomas, whereas these molecules were not localized in the spindle-shaped neoplastic myoepithelial cells of the myxoid element in these tumors. CDMP-2 was expressed neither in normal salivary glands nor in any elements of the pleomorphic adenomas. 3. In transmission electron microscopic view, the tumor cells are composed of modifed myoepithelial cells between hyaline and myxoid stroma. 4. In Immuno-blot analysis, strong overexpression of CDMP-1 was frequently seen in pleomorphic adenomas, but the level of CDMP-2 was expressed minimally in pleomorphic adenoma. From the these results, it should be suggested that undifferentiated neoplastic myoepithelial cells around the chondroid areas expressed CDMP-1 and suggested that this molecule may play a role in the differentiation of neoplastic myoepithelial cells in pleomorphic adenoma, but not CDMP-2.

• Preventive Nutrition and Food Science
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• 제4권1호
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• pp.6-13
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• 1999

The quality of the buckwheat bread made with previously heated ($55^{\circ}C$) and cooled buckwheat flour 0dough with the addition of ascorbic acid(AA) or/and sodium stearoyl lactylate(SSL) was evaluated . With heat treatemtn , handling property of dough and grain of the bread crumb were markedly improved and stickiness of the dough decreased . The optimum resting time to produce the best loaf volume and grain was found to be 3hr for both unheated and heated doughs. Heat treated dough showed higher dough expansion rate during fermentation than unheated dough, even though heated dough had lower loaf volume, probably because of an improper oven spring. Increase in shortening of dough formula from 3% to 5% improved loaf volume without improvement of handling property. With the addition of 100 ppm AA or/and 0.5% SSL, loaf volume and crumb grain were improved for both unheated and heated doughs.Microscopic analysis of a mixed dough by scanning electron microscope (SEM) showed that heated dough had a continuous network whereas unheated dough was discontinuous. The addition of AA and SSL gave the dough a more continuous network whereas unheated dough was discontinuous . The addition of AA and SSL gave the dough a more continuous structure with strengthened strands or interactions between the starch granule and protein. Therefore, it appears that the presence of continuity in heated buckwheat breadwheat bread dough is related to the improved loaf volume and crumb grain without dough stickness.

• Journal of Pharmaceutical Investigation
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• 제17권3호
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• pp.111-126
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• 1987

Methyl methacrylate-butyl methacrylate copolymer (MMBM)-dibutyl phthalate (DBP) films were investigated as a potential topical drug delivery system for the controlled release of nitrofurazone. The kinetic analysis of release data indicated that drug release followed a diffusion-controlled granular matrix model, where the quantity released per unit area is proportional to the square root of time. DBP of several hydrophobic plasticizers selected was found to give the highest release of nitrofurazone. However, hydrophilic plasticizers such as propylene glycol and polyethylene glycol 400 had no controlled release properties and acceptable film formation. The effects of changes in film composition, drug concentration, film thickness, pH of release medium, and temperature on the in vitro release of nitrofurazone were analyzed both theoretically and experimentally. The release rate constant (k') was found to be proportional to DBP content, pH, and the temperature of release medium, but independent of film thickness, and drug concentration in a range of 0.1-0.4% by weight. The linear relationship was found to exist between the log k' and DBP content. The release of nitrofurazone from MMBM-DBP (8:2) films was found to be an energy-linked process. Two energy terms were calculated ; the activation energy for matrix diffusion was 13.45 kcal/mole, and the heat of drug crystal solvation was 27.26-29.34 kcal/mole. Observation of scanning electron micrographs and microscopic photographs showed that the incorporation of DBP in films increased markedly the particle size of nitrofurazone dispersed in the film matrix, comparing with the fine dispersion of nitrofurazone in pure MMBM film alone.

• Applied Microscopy
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• 제31권2호
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• pp.117-128
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• 2001

DMF는 특별히 PVA에 대해 수소결합 등의 강한 상호작용을 하는 용매가 아니다. 오히려 UCST계로서 온도가 낮아질수록 상분리나 phase demixing을 일으킨다. PVA/DMF의 겔화는 x-ray 회절이나 열분석을 통해 crystallization-induced gelation으로 밝혀졌다. 그리고 겔화 온도가 낮을수록 결정화는 빠르게 진행되었다. 소량의 PEG는 PVA/DMF 겔 형성을 도왔으며 urea는 겔 형성을 방해하였다. 전자현미경은 이 겔화 과정을 잘 보여 주었다. 갓 만들어진 젤은 표면에 깊은 주름이 있으며 아직 상분리가 본격적으로 시작되기 전의 상태로서 아주 미세한 DMF가 차지하는 공간인 구멍들이 사진에 포착되지 않는다. Aging시간이 길어지면서 상분리가 시작되면 표면의 분화구가 나타나기 시작하며, 이 분화구는 원래 용매상이 차지하고 있던 공간으로서 phase demixing에 의해 PVA chain들은 분화구 주변으로 분리된다. 상분리과정에서 PVA chain들은 서로 당겨져서 표면적이 줄어듬과 동시에 분화구 크기도 커진다. Aging에 따른 x-ray결과와 열적 성질은 이 모든 과정을 뒷받침한다.

• Journal of Pharmaceutical Investigation
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• 제25권3호
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• pp.193-204
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• 1995

In order to examine the effect of extrahepatic cholestasis induced by common bile duct ligation on the hepatic function, the pharmacokinetics of antipyrine and d-propranolol were investigated in rats. In addition, in an attempt to observe the degree of direct hepatic injury, light and electron microscopic observations and conventional pathologic test using serum were performed. Five days after common bile duct ligation, antipyrine(15 mg/kg) and d-propranolol(3 mg/kg) were intravenously administrated to the rats, respectively. The total clearances of antipyrine and d-propranolol were significantly(p<0.05) decreased. Because hepatic clearance of antipyrine poorly extracted by the liver and that of d-propranolol highly extracted by the liver are respectively dependent on the hepatic intrinsic clearance and the hepatic blood flow, it may be concluded that extrahepatic cholestasis following five days after common bile duct ligation decreased the hepatic intrinsic clearance and the hepatic blood flow. SGPT, SGOT, cholesterol, bilirubin(total bilirubin, direct bilirubin) and alkaline phosphatase were significantly increased(p<0.05). The proliferation of bile ducts was prominent, and degeneration and necrosis of hepatocytes were observed by light microscope. Also, ultrastructurally, bile canaliculi were containing the amorphous materials and losing microvilli, and SER and RER in hepatocytes were dilated and vacuolated.

• Journal of Ginseng Research
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• 제16권3호
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• pp.222-227
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• 1992

Unlike carbohydrats and fats, alcohol is essentially foreign to the body and it is known that the body get rid of it by oxidizing alcohol maily in the liver. Acetaldehyde is produced during ethanol metabolism and is known to be oxidized mainly by aldehyde dehydrogenase (ALDH). ALDH activity was found mainly in the mitochondrial fraction but a significant ALDH activity was also present in microsomal and cytosol fraction. Wistar rats (150~200 g, male) were given freely with 12% ethanol (Control) and/or 12% ethanol containing 0.1% ginseng saponins (Test) instead of water for 6 days and the liver was analyzed. ALDH activities of both control and test group were lower than that of normal group but test AkDH was less inhibited than control. ADH activies of both control and test were slightly higher than that of normal group but our previous data showed that it became gradually steady after prolonged ethanol feeding. MEOS activities of both control and test group were much higher than that of normal group. MEOS enzymes are inducible but the activity of test group was greatly higher than that of control. Ethanol containing [1-i4C] ethanol (5 $\mu$Ci) was injected to the above three groups and 30 min later, the distribution of radioactivity of hepatic lipids was investigated. Radioactivities of hepatic lipids of both control and test group were higher than that of normal group, however, that of test group was much lower than that of control. Analysis of individual lipids showed that phospholipid biosynthesis was significantly impaired and fatty acid and triglycerides biosynthesis were greatly stimulated. However, it was realized that the saponin prevented phospholipid biosynthesis depression and the increase of triglyceride biosynthesis considerably. It seemed that the saponin might stimulate ADH, ALDH and MEOS and the acetaldehyde formed would be removed faster. The excess hydrogen can be shunt more quickly into lipid biosynthesis. Electron microscopic observation showed that the hepatic cell of control group was si gnificantly damaged. Mitochondria were swollen and rough endoplasmic reticulum were dilated, however, hepatocytes of test group were not damaged.

• 한국환경과학회지
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• 제6권3호
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• pp.249-258
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• 1997

Mercury- and cadmium-resistant bacteria were Isolated from an Industrial complex wastewater of Taejon area. All of them were motile, gram negative rods. In the results of physicochemical test and VITEK card test. HM1 was Identified with Achetobacter cd- coaceucus, CM3 was Identified 65 Commonas acidovorns, HM2, HM3, CMI , and CM4 were Pseudomonas sp., but HM4 and CM2 were unidenteed. They were tested for subceptlbility to 14 heavy metals. Mercury-resistant bacteria(HM1, HM2, HM3, and HM4) were sensitive to low concentration(100~400ppm) of $Cd^{2+}$, $Co^{2+}$. $Zn^{2+}$, and Ni2+, while cadmium-resistant bacteria(CM1, CM2, CM3, and CM4) showed resistance up to the high concentration(600~ 1, 200ppm) of these metal loons. As a result of resistance spectrum test of mercury-resistant bacteria, HM1 was broad-spectrum strain, HM2. HM3, and HM4 were narrow-spectrum stratas. Transmission electron microscopic examination of cell wall of HM1 culture grown with and without 100ppm of $HgCl_2$ showed remarkably merphological abnormalities. In the result of atomic absorption spectrometric analysis of cadmium-resistant bacteria grown at 200ppm of $CdCl_2$ for 6h, all of them accumulated cadrnium(14ppm~57ppm) In cell. In cadinium-resistant bacteria, CM1, CM2, and CM4 were spared from the Inhibitory effect of $Cd^{2+}$ by the addition of $Mn^{2+}$, CM4 were also spared from the Inhibitory effect of $Cd^{2+}$ by the addition of $Mn^{2+}$ as well as $Zn^{2+}$.

• Journal of Electrochemical Science and Technology
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• 제2권4호
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• pp.187-192
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• 2011

Photoelectrochemical performances of ZnO electrodes are enhanced by coupling with cobalt-based catalyst (CoPi) in phosphate electrolyte (pH 7). For this study, hexagonal pillar-shaped ZnO nanorods are grown on ZnO electrodes through a chemical bath deposition, onto which CoPi is deposited with different photodeposition times (10-30 min). A scanning electron microscopic study indicates that CoPi deposition does not induce any change of ZnO morphology and an energy-dispersive X-ray spectroscopic analysis shows that inorganic phosphate ions (Pi) exist on ZnO surface. Bare ZnO electrodes generate the current of ca. $0.36mA/cm^2$ at a bias potential of 0.5 V vs. SCE, whereas ZnO/CoPi (deposited for 10 min) has ca. 50%-enhanced current ($0.54mW/cm^2$) under irradiation of AM 1.5G-light ($400mW/cm^2$). The excess loading of CoPi on ZnO results in decrease of photocurrents as compared to bare ZnO likely due to limited electrolyte access to ZnO and/or CoPi-mediated recombination of photogenerated charge carriers. The primary role of CoPi is speculated to trap the photogenerated holes and thereby oxidize water into molecular oxygen via an intervalency cycle among Co(II), Co(III), and Co(IV).

• 대한화학회지
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• 제21권1호
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• pp.53-59
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• 1977

알루민산나트륨과 알루민산칼륨 용액에 $CO_2$가스 吹入法에 의해 $NaAlCO_3(OH)_2\;(Dawsonite)와\;KAlCO_3(OH)_2$를 合成하였다. 이 反應은 80 ∼ $90^{\circ}C$에서 $Na_2O/Al_2O_3,\;K_2O/Al_2O_3$의 몰比가 各 各 6∼8, 8∼10인 알루민산알칼리 용액중에 $CO_2$가스를 吹?하여 達成되었다. 알루민산알칼리 용액중에 $HCO_3^-$이 多量 存在하며 알루미나가 平衡固相으로서 Boehmite로 存在할 때 高純度의 Dawsonate와 $KAlCO_3(OH)_2$가 生成된다는 것을 알았다. 이런 條件下에서 合成된 Dawsonite와 $KAlCO_3(OH)_2$의 示性式은 赤外線吸收스펙트럼 分析結果 各各 $NaAlO(OH)HCO_3와\;KAlO(OH)HCO_3$로 나타내는 것이 妥當하다고 생각된다. 또 電子顯微鏡觀察로부터 Dawsonite는 纖維狀結晶, $KAlCO_3(OH)_2$는 針狀結晶으로 되어 있다는 것을 알았다.