• YAKHAK HOEJI
• /
• v.40 no.5
• /
• pp.522-531
• /
• 1996

5-fluorouracil(5-FU) derivatives synthesized with four N-acyloxycarbonyl group such as 1-(N-t-butyloxycarbonyl)glycyloxymethyl-5-FU(BGFU), 1-(N-t-butyloxycarbonyl)leucyloxymethy l-5-FU(BLFU), 1-(N-t-carbobenzyloxymethyl)glycyoxymethyl-5-FU(CGFU) and 1-(N-t-carbobenzyloxymethyl)leucyloxymethyl-5-FU(CLFU) were entrapped into liposomes with different lipid compositions. The entrapment efficiency and release rate of drugs from each liposomes were evaluated. The particle size of liposomes, cytotoxicity and stability of drug-entrapped in liposomes were evaluated. The entrapment efficiency in 5-FU derivatives liposomes was dependent on the lipophilicity of N-acyloxymethyl derivatives. The drug entrapment efficiency also increased on the content of lipid increased up to 200mcmol of lipid per milliliter of liposomal solution. However, inclusion of additives such as cholesterol, dicetylphosphate and stearylamine decreased the entrapment efficiency. The mean particle size and size distribution were varied with lipid compositions and lipophilicity of prodrugs. The release rates of drugs from liposomes were not affected by additives, but those of BGFU and CGFU entrapped in liposomes with cholesterol decreased. Cytotoxicity of BLFU and CLFU entrapped in liposomes decreased by 3~5 fold compared with those of free two prodrugs. Liposome-entrapped 5-FU prodrugs were more stable either at pH 7.4 or in human plasma. Especially, 5-FU prodrugs entrapped in liposome with dipalmitoylphosphatidylcholine(DMPC) was the most stable in human plasma. Compared with free BLFU, BLFU entrapped in DMPC liposome showed a superior antitumor activity at all doses used. In contrast, CLFU entapped in liposomes were more toxic than free prodrug.

• Animal cells and systems
• /
• v.9 no.3
• /
• pp.139-144
• /
• 2005

The attractant (orange light) or repellent (white light) signal is transmitted from SRI (Sensory Rhodopsin I) via protein-protein interaction with its transducer Htrl (Halobacterial Transducer for Sensory Rhodopsin I) which in turn controls a cytoplasmic phospho-transfer pathway that modulates flagella motor switching in Halobacterium salinarum. Some mutations in both SRI and Htrl showed an unusual mutant phenotype called inverted signaling, in which the cell produces a repellent response to normally attractant light. Twelve mutations at the Glutamate 56 (E56) position in the second transmembrane helix of Htrl were introduced by site-specific random mutagenesis. Almost all E56 mutants showed orange-light inverted responses in pH and temperature-dependent manners except E56D and E56Y. Except for these two mutants, all mutants accelerated the $S_{373}$ decay compared to wild-type at $18^{\circ}C$. This supported that there is an interaction between SRI and the second transmembrane of Htrl. Also a structural model of Htrl based on the Tar crystal structure and the secondary structure prediction program proposed the E56 residue to be in the middle of the proton channel. The most important observation is that the E56 mutant provides the evidence that this residue is very sensitive for signal relay, which can be explained by the open and closed conformations of the channel (A and R conformations) in SRI, as was postulated by the unified conformational shuttling model for transport and signaling.

• YAKHAK HOEJI
• /
• v.22 no.3
• /
• pp.163-174
• /
• 1978

Plantaginis seed has been applied in Chinese medicine a as well as in folk remedy. It was advocated that Plantaginis S Semeη exerts good therapeutic effects as anti-inflammatory, antitussive, obstipant and diuretic agent in some cases of alimentary, respiratory a and renal disorders. This study was carried out in order to r re-evaluate the pharmacological action, especially the hypotensive a action of Plantaginis Semen and to elucidate the mechanism of its a action, making use of Plantaginis Semen methanol extract (PME), because its basic pharmacological action, i. e., hypotensive action is n not clear. 1) PME, when administered into intravenous route, elicited the h hypotensive response dependent on the dose of PME given to the rabbit anesthetized with urethane. 2) This hypotensive response of P PME was inhibited by atropine and potentiated by physostigmine, but not influ$\varepsilon$need by vagotomization. 3) Depressor effect of PME was blocked by chlorisondamine, phentolamine, and bethanicline, while not altered by cyproheptadine, diphenhydramine and propran¬olol. 4) The secondary pressor response after blocking the depressor e effect of PME by chlorisondamine was produced, but this pressor response was deminished by atropine. 5) PME augmented the pressor e effect of norepinephrine and angiotensin, on the other hand, reduced b blood pressure elevated by carotid occlusion reflex. 6) These observa¬t tions suggest that PME may induce the hypotensive response via dual mechanisms of parasympathomimetic and sympatholytic action, that the positions of this action are cholinergic peripheral site and sympathetic ganglia respectively, and that PME may possess the pressor activity caused by stimulation of "atropine-sensitive site" which seems to existsin the sympathetic ganglia.

• Journal of Microbiology and Biotechnology
• /
• v.17 no.5
• /
• pp.822-829
• /
• 2007

A gene coding for phosphoketolase, a key enzyme of carbohydrate catabolism in heterofermentative lactic acid bacteria(LAB), was cloned from a Lactobacillus paraplantarum C7 and expressed in Escherichia coli. The gene is 2,502 bp long and codes for a 788-amino-acids polypeptide with a molecular mass of 88.7 kDa. A Shine-Dalgarno sequence(aaggag) and an inverted-repeat terminator sequence are located upstream and downstream of the phosphoketolase gene, respectively. The gene exhibits an identity of >52% with phosphoketolases of other LAB. The phosphoketolase of Lb. paraplantarum C7(LBPK) contains several highly conserved phosphoketolase signature regions and typical thiamine pyrophosphate(TPP) binding sites, as reported for other TPP-dependent enzymes. The phosphoketolase gene was fused to a glutathione S-transferase(GST::LBPK) gene for purification. The GST::LBPK fusion protein was detected in the soluble fraction of a recombinant Escherichia coli BL21. The GST::LBPK fusion protein was purified with a yield of 4.32mg/400ml by GSTrap HP affinity column chromatography and analyzed by N-terminal sequencing. LBPK was obtained by factor Xa treatment of fusion protein and the final yield was 3.78mg/400ml. LBPK was examined for its N-terminal sequence and phosphoketolase activity. The $K_M\;and\;V_{max}$ values for fructose-6-phosphate were $5.08{\pm}0.057mM(mean{\pm}SD)$ and $499.21{\pm}4.33{\mu}mol/min/mg$, respectively, and the optimum temperature and pH for the production of acetyl phosphate were $45^{\circ}C$ and 7.0, respectively.

• Journal of Microbiology and Biotechnology
• /
• v.26 no.8
• /
• pp.1428-1438
• /
• 2016

In the present work, Arthrobacter sp. 25, a lead-tolerant bacterium, was assayed to remove lead(II) from aqueous solution. The biosorption process was optimized by response surface methodology (RSM) based on the Box-Behnken design. The relationships between dependent and independent variables were quantitatively determined by second-order polynomial equation and 3D response surface plots. The biosorption mechanism was explored by characterization of the biosorbent before and after biosorption using atomic force microscopy (AFM), scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The results showed that the maximum adsorption capacity of 9.6 mg/g was obtained at the initial lead ion concentration of 108.79 mg/l, pH value of 5.75, and biosorbent dosage of 9.9 g/l (fresh weight), which was close to the theoretically expected value of 9.88 mg/g. Arthrobacter sp. 25 is an ellipsoidal-shaped bacterium covered with extracellular polymeric substances. The biosorption mechanism involved physical adsorption and microprecipitation as well as ion exchange, and functional groups such as phosphoryl, hydroxyl, amino, amide, carbonyl, and phosphate groups played vital roles in adsorption. The results indicate that Arthrobacter sp. 25 may be potentially used as a biosorbent for low-concentration lead(II) removal from wastewater.

• Progress in Superconductivity
• /
• v.14 no.1
• /
• pp.39-44
• /
• 2012

The fabrications condition and superconducting properties of top-seeded melt growth (TSMG) processed $GdBa_2Cu_3O_{7-y}$ (Gd123) bulk superconductors were studied. Processing parameters (a maximum temperature ($T_{max}$), a temperature for crystal growth ($T_G$) and a cooling rate ($R_G$) through a peritectic temperature ($T_P$) for the fabrication of single grain Gd123 superconductors were optimized. The magnetic levitation forces, trapped magnetic fields, superconducting transition temperature ($T_c$) and critical current density ($J_c$) of the Gd123 bulks superconductors were estimated. Single grain Gd123 bulk superconductors were successfully fabricated at the optimized processing condition. The $T_c$ of a TSMG processed Gd123 sample was 92.5 K and the $J_c$ at 77 K and 0 T was approximately $50kA/cm^2$. The trapped magnetic field contour and magnetic levitation forces were dependent on the top surface morphology of TSMG processed Gd123 samples. The single grain Gd123 samples, field-cooled at 77 K using a Nd-B-Fe permanent magnet with 5.27 kG and 30 mm dia., showed the trapped magnetic field contour of a single grain with a maximum of 4 kG at the sample center. The maximum magnetic levitation forces of the single grain Gd123 sample, field-cooled or zero field-cooled, were 40 N and 107 N, respectively.

• Journal of Korean Society of Water and Wastewater
• /
• v.24 no.1
• /
• pp.51-62
• /
• 2010

The high concentration of N in the wastewater from livestock farming generally renders the efficiency of the wastewater treatment. Therefore, removal of N in livestock wastewater is crucial for successful treatment. The current study was conducted to investigate the optimum conditions for partial nitrification under anaerobic condition following nitritation in TPAD-BNR(two-phase anaerobic digestion-biological nitrogen removal) operating system. Sequential operating test to stimulate partial nitrification in reactor showed that partial nitrification occurred at a ratio of 1.24 in $NO_2{^-}$-N:$NH_4{^+}$-N. With this result, a wide range of factors affecting stable nitritation were examined through regression analysis. In the livestock wastewater treatment procedure, the hydraulic retention time (HRT) and pH range for optimum nitrite accumulation in the reactor were 1-1.5 days and 7-8, respectively. It was appeared that accumulation of $NO_2{^-}$-N in the reactor is due to inhibition of the $NO_2{^-}$-N oxidizer by free ammonia (FA) while the effect of free nitrous acid was minimal. Nitrification was not influenced by DO concentration at a range of 2.0-3.0 mg/L and the difference in the growth rate between $NH_4{^+}$-N oxidizer and $NO_2{^-}$-N oxidizer was dependent on the temperature in the reactor.

• Korean Journal of Microbiology
• /
• v.9 no.1
• /
• pp.39-45
• /
• 1971

During the sporulation stage in Saccharomyces cerevisiae J170, the incorporation of D$^{14}$ C-glucose into starved cells of sporulation stage as well as the vegetative one is appeared higher at pH 6.0. Glucose transport system, in both the vegetative and sporulation stage, is associated with "energy dependent" as the result of repression by such a respiratory inhibitor as 2,4-dinitrophenol. The Km value of glucose uptake in vegetative stage and sporulation stage was 2.1 mM and 2.5 mM respectively, indicating that the glucose is considerably reuqired for vegetative growth. Competition and countertranspoer of glucose by frutose and galactose are more distinct in vegetative stage, comparing with sporulation stage. The main sugar components of yeast cells consists of ribose, mannose, and .apha., .betha.-glucose. Amounts of mannose is lower in the aporulation stage than that in the vegetative stage.ive stage.

• The Korean Journal of Food And Nutrition
• /
• v.30 no.5
• /
• pp.860-866
• /
• 2017

This study was conducted to assess effects of addition of walnuts on soy sauce quality. The pH was significantly increased by adding more than 4 percent of walnuts. As the addition of walnuts increased, Hunter's color values and brown color increased. Total solid of soy sauce did not change significantly with the addition of walnuts. Crude fat content increased by two times in the 2 percent added walnuts group compared to the control group, but it was not dependent on the addition of walnuts. DPPH radical scavenging activity was significantly increased with the addition of walnuts. The addition of walnuts decrease saturated fatty acids and increased unsaturated fatty acids. Composition ratio of linoleic acid was highest in the control group and all the additions. These results revealed that soy sauce made with walnuts have a positive effect on functionality and preference.

• The Korean Journal of Food And Nutrition
• /
• v.30 no.4
• /
• pp.673-680
• /
• 2017

Fludarabine, a chain terminating anti-cancer drug, is a purine analogue that causes DNA strand breaks in normal cells. In this study, we determined if A. melanocarpa and Korean red ginseng extract mixture reduce cytotoxicity of fludarabine. Treatment of HaCaT cells with $10{\mu}M$ of fludarabine for 24 hours decreased cell viability and increased DNA strand breaks. Treatment of A. melanocarpa and Korean red ginseng extract mixture for 24 hours increased cell viability as compared with single extract treatment. The protective effect of these extracts on cell activity increased in a concentration-dependent manner. DNA strand breaks induced by fludarabine decreased as concentration of extract mixture increased. p-H2AX level, a marker of DNA strand breakage, decreased depending on the concentration of extract mixture. The effect of mixed extract of A. melanocarpa and Korean red ginseng on DNA damage is due to the anti-oxidative effect of A. melanocarpa and signal transmission through glucocorticoid receptor upon binding of saponin of Korean red ginseng.