• Title/Summary/Keyword: stable pH

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Purification and Characterization of Degradative Enzyme of Dental Plaque from Streptomyces sp. Y9343 (Streptomyces sp. Y9343이 生産하는 齒面細菌膜 分解酵素의 精製와 特性)

  • Kim, Seong-Joo;Han, Hong-Keun;Yoon, Jeong-Weon
    • Microbiology and Biotechnology Letters
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    • v.24 no.1
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    • pp.9-18
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    • 1996
  • Streptococcus mutans has been implicated as primary causative agents of dental caries by insoluble glucan (IG) in human and experimental animals. An attempt was made to search for the ${\alpha}$-1,3 glucanase that degrades IG produced by S. mutans. ${\alpha}$-1,3 glucanase was detected in the culture supernatant of microorganisms, which are isolated from soils on agar medium containing IG as a sole carbon source. This Streptomyces sp. hydrolysed IG produced by immobilized S. mutans and was named as Y9373. This enzyme required ${\alpha}$-1,3 glucan (IG) as an inducer. The optimum conditions for enzyme production were studied. The enzyme was purified by 30~70% $(NH_4)_2SO_4$ precipitation, anion exchange chroma tography on DEAE-cellulose and gel filtration on Sepadex G-75. The purified enzyme has a specific activity of 7840.0 U/mg protein giving 32.1-fold purification and final yield of 0.53%. The molecular weight was estimated to be about 22.5 kDa by SDS-PAGE. The optimum pH and temperature for enzyme reaction were 6.5 and 37$^{\circ}C$, respectively and the enzyme was relatively stable at the temperature below 60$^{\circ}C$. The activity of purified enzyme was enhanced by adding $Co^{2+},\;Mn^{2+}\;and\;Mg^{2+}$ into the medium, whereas inhibited by adding $Hg^{2+},\;Zn^{2+}$ and SDS. The $K_m\;and\;V_{max}$ value of ${\alpha}$-1,3 glucanase for IG were estimated to be 2.50 mM and 0.0431 mM/min, respectively. The thin layer chromatographic analysis of hydrolysates from IG with ${\alpha}$-1,3 glucanase showed that glucose was the main product of reaction. This enzyme activity was about 14 times higher than marketing dextranase as preventive agent against artificial dental caries by S. mutans in TH medium including 5% sucrose after 30 minutes.

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Aminopropyl Functionalized Silica Nanoparticle Dispersed Nafion Composite Membranes for Vanadium Redox Flow Batteries (아미노프로필 관능기를 갖는 실리카 나노 입자가 분산된 나피온 복합막을 이용한 바나듐 레독스 흐름 전지)

  • Lee, Doohee;Yu, Duk Man;Yoon, Sang Jun;Kim, Sangwon;So, Soonyong;Hong, Young Taik
    • Membrane Journal
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    • v.30 no.5
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    • pp.307-318
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    • 2020
  • Conventional perfluorinated sulfonic acid membrane, Nafion is widely used for vanadium redox flow battery (VRFB). It is desired to prevent vanadium ion permeation through a membrane to retain the capacity, and to keep the cell efficiency of a VRFB. Highly proton conductive and chemically stable Nafion membranes, however, suffer from high vanadium permeation, which induce the reduction in charge and discharge capacity by side reactions of vanadium ions. In this study, to resolve the issue, silica nanoparticles, which are functionalized with 3-aminopropyl group (fS) are introduced to enhance the long-term performance of a VRFB by lowering vanadium permeation. It is expected that amine groups on silica nanoparticles are converted to positive ammonium ion, which could deteriorate positively charged vanadium ions' crossover by Gibbs-Donnan effect. There is reduction in proton conductivity may due to acid-base complexation between fS and Nafion side chains, but ion selectivity of proton to vanadium ion is enhanced by introducing fS to Nafion membranes. With the composite membranes of Nafion and fS, VRFBs maintain their discharge capacity up to 80% at a high current density of 150 mA/㎠ during 200 cycles.

Classification and Characterization of Bacteriophages of Lectobacillus casei (Lactobacillus casei Bacperiophage의 분류 및 특성에 관한 연구)

  • 김영창;박민철;강국희;윤영호;이광웅
    • Korean Journal of Microbiology
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    • v.17 no.4
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    • pp.165-178
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    • 1979
  • Phages of Lactobaciilus casei (PLC) isolated from plant drainage were classified and characterized. The results are as follows : 1. On the basis of host range pattern, phages could be divided into 2 groups (PLC-B and PLC-C). PLC-B group phages could be further divided into 5 sub-groups $(B_1, \;B_2, \;B_3, \;B_4, \;and\;B_5)$. Although PLC-C group phages had the same host range, they could be also divided into 2 sub-groups $(C_1\;and\;C_2)$ by morphlogical type. 2. It was $B_3$ group phages that represented a major proportion (44.4%) of phages tested. However, $B_1$ group phages were shown to have the widest host range. 3. Electron micrographs revealed that the phages fell into three different morphological types. $(B_1, \;B_2, \;and\;B_3)$ group phages hd a hexagonal head (52nm in diameter) and a sheathless noncontractile (245 nm in length). $B_4\;and\;C_2$ group phages had a hexagonal head (56 nm) and a short flexible tail (169nm) having no sheath. $B_5\;and\;C_1$ group phages were shown to have a hexagonal head (81 nm) and a contractile tail (140 nm) having a sheath, a base plate and tail fibers. 4. The inactivation of the phages by antisera indicated that serological relationships correlated completely with morphological types. 5. $B_1, \;C_1\;and\;C_2$ group phages produced a large (1, 2 mm in diameter) plaque with a clear ring. The morphology of plaques of $B_3\;and\;B_5$ group phages was the same as those produced by the above, but the average plaque sizes for $B_3\;and\;B_5$ were 0.8 mm abd 0.5 mm, respectively. $B_2\;and\;B_4$ group phages produced a small (0.5 mm) turbid plaque with an irregular edge. 6. The latent period and the average burst size of $B_1\;and\;B_3$ group phages were 90 min and 100, respectively. These phages reuqired calcium ions for their miltiplication. 7. $B_3$ group phages could not be absrobed to R-variant $KC_1$. 8. The order of resistance of phages to heat was $B_2\;>\;B_1, B_4\;and\;B_5\;>\;B_3\;and\;C_2, \;B_5$ group phages were more stable than $B_3$ in various pH values. $C_2$ group phages were more sensitive to UV irradiation than $B_1\;and\;B_3$ group phages. 9. Strains YIT9018 and IAM 1043 were induced by mitomycin C treatment. Phage particles detected in the lysates had a hexagonal head (38 and 49 nm, respectively), but no tail. Any sensitive indicator strain could not be isolated in spite of repaeated trials.

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In vivo comparison of Lu-177-labeled phosphonate compounds as potential agents for bone pain palliation in rodents

  • Chang, Young Soo;Lee, Yun-Sang;Kim, Young Ju;Jeong, Jae Min
    • Journal of Radiopharmaceuticals and Molecular Probes
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    • v.1 no.1
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    • pp.53-61
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    • 2015
  • Lutetium-177 ($T_{1/2}=6.71day$) is an adequate radionuclide for therapy, which has both beta emission ($E_{max}=497keV$) for therapeutic effect and gamma emission (113 and 208 keV) for imaging. $^{177}Lu$ labeled ethylenediamine-N,N,N',N'-tetrakis (methylene phosphonic acid) (EDTMP) and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraaminomethylenephosphonate (DOTMP) have been proposed as radiopharmaceuticals for bone pain palliation. In this study, we compared radiochemistry and biodistribution of $^{177}Lu$-EDTMP and $^{177}Lu$-DOTMP. EDTMP and DOTMP were synthesized, and 1 mg of each was labeled with $^{177}Lu$ at pH 7~8 with high efficiency (>98%). For comparative biodistribution studies, $^{177}Lu$-EDTMP or $^{177}Lu$-DOTMP were injected into ICR-mice through tail vein, and then biodistribution data were obtained as percentages of injected dose per gram of tissue (% ID/g). Urine excretions of both agents in mice were checked for 7 days. Rat images were also obtained after injection of $^{177}Lu$-EDTMP or $^{177}Lu$-DOTMP. $^{177}Lu$-DOTMP (100% at 1 min) showed faster labeling than $^{177}Lu$-EDTMP (100% at 30 min). Both of them were stable at least for 21 days at room temperature. High bone uptakes were found for both $^{177}Lu$-EDTMP and $^{177}Lu$-DOTMP: 38.0 and 34.1% ID/g at 3 hr, respectively; and 33.2 and 18.8% ID/g at 7 day, respectively. Rapid excretions to urine were found for both agents ($^{177}Lu$-EDTMP: 56%, $^{177}Lu$-DOTMP: 63% at 1 day). Other organs showed very low uptakes. Rat images of both $^{177}Lu$-EDTMP and $^{177}Lu$-DOTMP showed high bone uptakes and low soft tissue uptakes. In conclusion, both $^{177}Lu$-EDTMP and $^{177}Lu$-DOTMP showed high potential as bone pain palliation agents. $^{177}Lu$-EDTMP showed higher bone uptake and slower bone clearance in mice than those of $^{177}Lu$-DOTMP.

Habitat Characteristics and Distribution of Cymbidium kanran Native to Jejudo, Korea (제주한란의 자생환경 특성 및 분포에 관한 연구)

  • Lee, Jong Suk
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.7 no.1
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    • pp.40-49
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    • 2004
  • This work carried out to define the characteristic of Cymbidium kanran habitat at Mt. Halla in Jejudo, Korea from the ecological point of view including geological and topographical features, air and soil temperature, relative humidity, fluctuations of light intensity, habitat vegetation, distribution altitude, area limit, and etc. And another goal of this study consider the conservation counterplan of the cymbidium habitat. Natural distribution areas of the cymbidium were observed more abundantly on the well drained south and east-facing slopes. Soil acidity was ranged from pH 4.1 to 5.3, and electric conductivity was ranged from 176.4 to 299.9 us/cm (average 215.3 us/cm). Base-saturation percentage of the habitat soil was below 50%, bulk density 0.42g/$cm^2$, particle density 2.05g/$cm^2$, humus content 26%, total nitrogen 0.82%, available phosphate 4.2 mg/kg, exchangeable potassium 0.63 Cmol/kg, calcium 0.44 Cmol/kg and magnesium 0.67 Cmol/kg. Annual mean air temperature was $15.4^{\circ}C$, however, air temperature was ranged $11.7{\sim}18.2^{\circ}C$ in spring, $21.2{\sim}23.8^{\circ}C$ in summer, $12.8{\sim}22.0^{\circ}C$ in fall and $5.5{\sim}7.8^{\circ}C$ in winter season. Annual mean soil temperature at depth of 10cm was $13.2^{\circ}C$ And minimum value was recorded $4.7^{\circ}C$ on January, and maximum value $22.5^{\circ}C$ on August. Relative humidity was ranged 90.8~94.7% in summer, 80.8~91.5% in fall and 77.6~84.2% in winter season. Minimum value was 56.5% on December, and maximum value was 100% on July and August. Light intensities were ranged from 400 to 1,800 lux at the greater part of Cymbidium kanran sites in Jejudo. Summer regarded as an lower light intensities was recorded to be range of 500~600 lux; however, autumn and winter were shown higher light regimes ranged from 3,500 to 3,800 lux. Therefore, one must be suprised that the cymbidium grow at the light condition of 6 lux (minimum) or 10,000 lux (maximum). Tree species keeping higher frequency rate and density were Eurya japonica, Camellia japonica, Castanopsis cuspidata, Carpinus laxiflora and Pinus densiflora. Number of trees growing in a 5${\times}$5m quardrat was 35 as an average, and proportion of evergreen versus deciduous was 5:1. Distribution altitude of the orchid habitat was ranged from 120m (low) to 840m (high) from sea level on the south facing slope of Mt. Halla, and was ranged eastern borderline of Gujwaup, Bukjejugun to western boundaries of Jungmundong, Seogwipo city. For the stable conservation of Cymbidium kanran habitat, sunlight regimes must be increased more by means of cutting trees or twigs in the site.

A Study for the Biologic Changes and Viability of Adipose tissue in Cryopreserved Fat Graft (냉동보관 후 이식한 지방조직의 생물학적 변화와 생존에 관한 연구)

  • Han, Jae-Jeong;Kwon, Yong-Seok;Lee, Jang-Ho;Heo, Jung;Lee, Keun-Cheol;Kim, Myung-Hoon;Kim, Seok-Kwun
    • Archives of Plastic Surgery
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    • v.36 no.2
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    • pp.127-134
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    • 2009
  • Purpose: Adipose tissue injection as a free graft for the correction of soft - tissue deficiency or depression deformity is a widespread procedure in plastic surgery. This study is to analyze the changes and viability of cryopreserved adipose tissue and to find out efficient long - term storage period. Methods: After centrifugation of aspirated abdominal tissues, $10m{\ell}$ of packed Adipose tissue were freezed at $-20^{\circ}C$. For 2, 4, 6, 8 months, each frozen samples were taken and injected into scalp of SCID mice. After 15 weeks, injected Adipose tissue were sampled and analyzed at 2 months interval. We compared and analyzed each group about the weight of the injected fat, histologic impressions, activity of mitochondria, size of a fat cell and rate of survival. Results: Significant weight changes were observed in cryopreservation for 2 months(p<0.05). Histologic changes were observed, independent of the freezing period with H - E stain. Among cryopreservations for 2, 4, 6 months, no significant change were observed. The reduction of mitochondrial enzymatic activity was observed independent of time interval but activity of mitochondrial dehydrogenase was reduced less than 50% in MTT assay. Conclusion: Freezing in $-20^{\circ}C$ for 6 months has no adverse effect to Adipose tissue, but fragile adipocytes, damaged cell membrane during harvesting procedure, were disrupted within 1 - 2 month and the maximum volume reduction were followed less than 2 months. These results demonstrate that tissue preparation cells without membrane damage have the greatest viability level and cryopreservation less than 2 months has great volume effect and cryopreservation for 6 months has stable volume effect.

Spheroplast Formation, Regeneration and Fusion of Flavimonas oryzihabitans KU21 (Flavimonas oryzihabitans KU21의 원형질체 생성, 재생 및 융합)

  • 이수연;임영복;박용근;이영록
    • Korean Journal of Microbiology
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    • v.31 no.4
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    • pp.318-325
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    • 1993
  • The optima] conditions for the formation, the regeneration. and the spheroplast fusion of Flavimonas aryz/habitans spheroplasts were investigated. Cells were transformed to spherop]asts effectively by treatment of 0.5% volume (v/v) of 0.] M EDTA and ]00 flg/ml lysozyme at $37^{\circ}C$ for 30 min without shaking. Magnesium chloride and calcium chloride were effective on the stabilization of spheroplasts. and 20 mM calcium chloride in the rich regeneration medium improve the yield of regenerants as much as 3.5-fo]d. Addition of 0.8% bovine serium albumine (BSA) in dilution buffer for spheroplast formation improved the stabilization of spheroplasts over extended periods (4-6 hr) at room temperature. and thus increased the yield of recombinants to 4.5-fold. The spheroplast formation frequency and regeneration frequency of F aryzihabitans strain was 90.10% and 3.800/." respectively. The first regenerated cell of F. aryzihabitans spheroplasts were appeared 6 hours after plating. By I I hours after plating, 80% of spheroplasts were regenerated on thc rich regeneration medium containing 0.5 M sucrose. The intraspeci11c spheroplast fusion of F urvz/habitans was carried out and the properties of obtained fusants were investigated. Formation of fusion products was effective when the Flav/munas spheroplast mixture was treated with 40%(w/v) PEG6000 and 20 mM CaCl, for 10 min at room temperature. and thc formation of frequency of recombinants were $2.0{\times}10^{-5}~3.6{\times}10^{-5}$. All tested recombinant clones were very stable on further propagation.

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Silver nanowires and nanodendrites synthesized by plasma discharge in solution for the catalytic oxygen reduction in alkaline media

  • Kim, Hoe-Geun;Song, Myeon-Gyu;Kim, Dong-U;Lee, Sang-Yul
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2018.06a
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    • pp.62-62
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    • 2018
  • Pt is still considered as one of the most active electrocatalysts for ORR in alkaline fuel cells. However, the high cost and scarcity of Pt hamper the widespread commercialization of fuel cells. As a strong candidate for the replacement of Pt catalyst, silver (Ag) has been extensively studied due to its high activity, abundance, and low cost. Ag is more stable than Pt in the pH range of 8~14 as the equilibrium potential of Ag/Ag+ being ${\approx}200mV$ higher than that of Pt/PtO. However, Ag is the overall catalytic activity of Ag for oxygen reduction reaction(ORR) is still not comparable to Pt catalyst since the surface Ag atoms are approximately 10 times less active than Pt atoms. Therefore, further enhancement in the ORR activity of Ag catalysts is necessary to be competitive with current cutting-edge Pt-based catalysts. We demonstrate the architectural design of Ag catalysts, synthesized using plasma discharge in liquid phase, for enhanced ORR kinetics in alkaline media. An attractive feature of this work is that the plasma status controlled via electric-field could form the Ag nanowires or dendrites without any chemical agents. The plasma reactor was made of a Teflon vessel with an inner diameter of 80 mm and a height of 80 mm, where a pair of tungsten(W) electrodes with a diameter of 2 mm was placed horizontally. The stock solutions were made by dissolving the 5-mM AgNO3 in DI water. For the synthesis of Agnanowires, the electricfield of 3.6kVcm-1 in a 200-ml AgNO3 aqueous solution was applied across the electrodes using a bipolar pulsed power supply(Kurita, Seisakusyo Co. Ltd). The repetition rate and pulse width were fixed at 30kHz and 2.0 us, respectively. The plasma discharge was carried out for a fixed reaction time of 60 min. In case of Ag nanodendrites, the electric field of 32kVcm-1 in a 200-ml AgNO3 aqueous solution was applied and other conditions were identical to the plasma discharge in water in terms of electrode configuration, repetition rate and discharge time. Using SEM and STEM, morphology of Ag nanowires and dendrites were investigated. With 3.6 kV/cm, Ag nanowire was obtained, while Ag dendrite was constructed with 32 kV/cm. The average diameter and legth of Ag nanowireses were 50 nm and 3.5 um, and thoes values of Ag dendrites were 40 nm and 3.0 um. As a results of XPS analysis, the surface defects in the Ag nanowires facilitated O2 incorporation into the surface region via the interaction between the oxygen and the electron cloud of the adjacent Ag atoms. The catalytic activity of Ag for oxygen reduction reaction(ORR) showed that the catalytic ORR activity of Ag nanowires are much better than Ag nanodendrites, and electron transfer number of Ag nanowires is similar to that of Pt (${\approx}4$).

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Enhancement of Antimicrobial Activity of Nano-Encapsulated Horseradish Aqueous Extracts Against Food-Borne Pathogens (고추냉이 수용성 추출물의 나노 입자화를 통한 식중독 미생물에 대한 항균 활성 증진)

  • Seo, Yong-Chang;Choi, Woon-Yong;Kim, Ji-Seon;Zou, Yun-Yun;Lee, Choon-Geun;Ahn, Ju-Hee;Shin, Il-Shik;Lee, Hyeon-Yong
    • Korean Journal of Medicinal Crop Science
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    • v.18 no.6
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    • pp.389-397
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    • 2010
  • This work was to improve antimicrobial activities of horseradish by encapsulated with edible biopolymers such as lecithin and gelatin since it has been difficult to directly use horseradish extracts into foods and food containers due to its strong and undesirable flavors. It was shown that most of the nanoparticles containing the extracts were well formed in round shape with below 400 nm diameter as well as fairly stable and less odd flavors in various pH ranges by measuring zeta potentials. The encapsulation efficiencies of nanoparticles were estimated as 66.6% and 53.4% for lecithin and gelatin, respectively. Minimal Inhibitory Concentration (MIC) of both nanoparticles against G(+), Listeria monocytogenes and G(-), Salmonella typhimurium were also measured as 79 ppm based on AIT concentrations in the extracts, whose activities were about 65% higher than the case of adding crude extract. It was also found that the nanoparticles efficiently penetrated into the cell membrane and started to destruct the cells after 6 hours cultivation under Transmision Electron Microscopy observation. These results prove that the nano-encapsulation of the horseradish extracts can be employed to directly treat into the foods and food containers for antimicrobial purposes with the aids of aerosolization system, by using small amounts of the extracts and having less flavors due to masking effects of nanoparticles.

Validated HPLC Method for the Pharmacokinetic Study of Atenolol and Chlorthalidone Combination Therapy in Korean Subjects

  • Kang, Hyun-Ah;Kim, Hwan-Ho;Kim, Se-Mi;Yoon, Hwa;Cho, Hea-Young;Oh, Seaung-Youl;Choi, Hoo-Kyun;Lee, Yong-Bok
    • Journal of Pharmaceutical Investigation
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    • v.36 no.5
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    • pp.331-338
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    • 2006
  • A rapid, selective and sensitive reverse-phase HPLC methods for the determination of atenolol and chlorthalidone in human serum and whole blood were validated, and applied to the pharmacokinetic study of atenolol and chlorthalidone combination therapy. Atenolol and an internal standard, pindolol, were extracted from human serum by liquid-liquid extraction, and analyzed on a $\mu$-Bondapak C18 $10-{\mu}$ column in a mobile phase of methanol-0.01 M potassium dihydrogenphosphate(30:70, v/v, adjusted to pH 3.5) and fluorescence detection(emission: 300 nm, excitation: 224 nm). Chlorthalidone and an internal standard, probenecid, were extracted form human whole blood by liquid-liquid extraction, and analyzed on a Luna C18 $5-{\mu}$ column in a mobile phase of acetonitrile containing 77% 0.01 M sodium acetate and UV detection at 214 nm. These analysis were performed at three different laboratories using the same quality control(QC) samples. The chromatograms showed good resolution, sensitivity, and no interference by human serum and whole blood, respectively. The methods showed linear responses over a concentration range of 10-1,000 ng/mL for atenolol and 0.05-20 ${\mu}g/mL$ for chlorthalidone, with correlation coefficients of greater than 0.999 at all the three laboratories. Intra- and inter-day assay precision and accuracy fulfilled international requirements. Stability studies(freeze-thaw, short-, long-term, extracted sample and stock solution) showed that atenolol and chlorthalidone were stable. The lower limit of quantitation of atenolol and chlorthalidone were 10 ng/mL and 0.05 ${\mu}g/mL$, respectively, which was sensitive enough for pharmacokinetic studies. These methods were applied to the pharmacokinetic study of atenolol and chlorthalidone in human volunteers following a single oral administration of Hyundai $Tenoretic^{\circledR}$ tablet(atenolol 50 mg and chlorthalidone 12.5 mg) at three different laboratories.