• The Korean Journal of Physiology and Pharmacology
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• v.10 no.1
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• pp.19-24
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• 2006

The intermediate conductance $Ca^{2+}-activated$ $K^+$ channels (SK4, IKCa1) are present in lymphocytes, and their membrane expression is upregulated by various immunological stimuli. In this study, the activity of SK4 was compared between Bal-17 and WEHI-231 cell lines which represent mature and immature stages of murine B lymphocytes, respectively. The whole-cell patch clamp with high-$Ca^{2+}$ ($0.8{\mu}M$) KCl pipette solution revealed a voltage-independent $K^+$ current that was blocked by clotrimazole (1 mM), an SK4 blocker. The expression of mRNAs for SK4 was confirmed in both Bal-17 and WEHI-231 cells. The density of clotrimazole-sensitive SK4 current was significantly larger in Bal-17 than WEHI-231 cells ($-11.4{\pm}3.1$ Vs. $-5.7{\pm}1.15$ pA/pF). Also, the chronic stimulation of B cell receptors (BCR) by BCR-ligation (anti-IgM Ab, $3{\mu}g$/ml, 8∼12 h) significantly upregulated the amplitude of clotrimazolesensitive current from $-11.4{\pm}3.1$ to $-53.1{\pm}8.6$ pA/pF in Bal-17 cells. In WEHI-231 cells, the effect of BCR-ligation was significantly small ($-5.7{\pm}1.15$ to $-9.0{\pm}1.00$ pA/pF). The differential expression and regulation by BCR-ligation might reflect functional changes in the maturation of B lymphocytes.

• Korean journal of food and cookery science
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• v.27 no.3
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• pp.29-37
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• 2011

Protease activity of fig (Ficus carica L.), cultivated in Korea was estimated. In particular, the proteolytic effect on myofibrilar protein was studied. A crude protease extract of fig was prepared in two ways; fig was homogenized in buffer followed by centrifugation, and the supernatant was precipitated by saturated ammonium sulfate followed by dialysis. The former method resulted in 41.15 mM/g fig protease activity, whereas the latter method resulted in 17.65 mM/g fig protease activity. The crude fig protease extract showed high specificity for casein as a substrate followed by egg white, bovine serum albumin, myofibrilar protein, collagen, and elastin. The extract had stable proteolytic activity in a pH range of 6.5~9.0 (optimal at pH 7-8) but lost activity, at pH 2-3. Proteolytic activity for myofibrilar protein was sensitive to pH. The proteolytic activity of the fig extract was steady up to $60^{\circ}C$ but declined at higher temperature. It also began to lose stability in salt concentrations >0.7 M NaCl. Fig has been used as a meat tenderizer for cooking, and these results support the tenderizing effectiveness of fig, particularly for Korean style meat marinating.

• Bulletin of the Korean Chemical Society
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• v.23 no.4
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• pp.549-554
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• 2002

Thermosensitive poly(organophosphazenes) bearing methoxy-poly(ethylene glycol) (MPEG) and alkylamines as substituents have been synthesized and characterized by elemental analysis, NMR spectroscopy, GPC, and DSC. All the polymers exhibited crystallinity, which was probably induced by the MPEG side chain of the polymers. All the polymers exhibited the lower critical solution temperature (LCSTs) in the range of 28 to $94^{\circ}C$ depending on several factors such as mole ratio of the substituents, kinds of PEG and alkylamines. The higher content of MPEG and shorter chain length of alkylamines of the polymers afforded the higher LCST. The LCSTs of the polymers exhibited almost concentration-independent behavior in the range of 3-30 wt % of the polymers in aqueous solutions. The polymers showed the higher LCSTs in the acidic solutions than in the neutral and basic solutions. The ionic strength of the polymer solution affected the LCST, which decreased with increased NaCl concentration. The polymer bearing almost equimolar substitutuents with the -N-P-N- unit has shown the LCST more sensitive to NaCl and pH than that with the -N-P-O- unit. The polymers were found to degrade in acidic solution but be very stable in alkali solution as well as in the buffer solution of pH 7.4.

• The Korean Journal of Physiology and Pharmacology
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• v.17 no.5
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• pp.463-468
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• 2013

Acute hypoxia induces contraction of pulmonary artery (PA) to protect ventilation/perfusion mismatch in lungs. As for the cellular mechanism of hypoxic pulmonary vasoconstriction (HPV), hypoxic inhibition of voltage-gated $K^+$ channel (Kv) in PA smooth muscle cell (PASMC) has been suggested. In addition, our recent study showed that thromboxane $A_2$ ($TXA_2$) and hypoxia-activated nonselective cation channel ($I_{NSC}$) is also essential for HPV. However, it is not well understood whether HPV is maintained in the animals exposed to ambient hypoxia for two days (2d-H). Specifically, the associated electrophysiological changes in PASMCs have not been studied. Here we investigate the effects of 2d-H on HPV in isolated ventilated/perfused lungs (V/P lungs) from rats. HPV was almost abolished without structural remodeling of PA in 2d-H rats, and the lost HPV was not recovered by Kv inhibitor, 4-aminopyridine. Patch clamp study showed that the hypoxic inhibition of Kv current in PASMC was similar between 2d-H and control. In contrast, hypoxia and $TXA_2$-activated $I_{NSC}$ was not observed in PASMCs of 2d-H. From above results, it is suggested that the decreased $I_{NSC}$ might be the primary functional cause of HPV disappearance in the relatively early period (2 d) of hypoxia.

• The Plant Pathology Journal
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• v.37 no.1
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• pp.79-85
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• 2021

Chemical and biological agents were evaluated to inhibit Colletotrichum fructicola, Phytophthora cactorum, and Lasiodiplodia theobromae causing strawberry diseases. Mycelial growths of C. fructicola were gradually arrested by increasing concentrations of fungicides pyraclostrobin and iminoctadine tris (albesilate). P. cactorum and L. theobromae were more sensitive to pyraclostrobin compared to C. fructicola, but iminoctadine tris (albesilate) was not or less effective to limit P. cactorum or L. theobromae, respectively. Bacillus siamensis H30-3 was antagonistic against the three pathogens by diffusible as well as volatile molecules, and evidently reduced aerial mycelial formation of P. cactorum. B. siamensis H30-3 growth was declined by at least 0.025 mg/ml of pyraclostrobin. The two fungicides additively inhibited mycelial growths of C. fructicola, but not of P. cactorum and L. theobromae. B. siamensis H30-3 volatiles led to less growth of C. fructicola than one reduced by the fungicides. Taken together, in vitro antimicrobial activities of the two fungicides together with or without B. siamensis H30-3 volatiles may be cautiously incorporated into integrated management of strawberry diseases dependent on causal pathogens.

• Korean Journal of Food Science and Technology
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• v.37 no.6
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• pp.951-956
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• 2005

Selection of oxygen-tolerant strains and elucidation of their oxygen tolerance mechanism were crucial for effective use of bifidobacteria. Oxygen-tolerant bifidobacteria were able to significantly remove environmental oxygen (oxygen removal activity) as compared to oxygen-sensitive strains. Most oxygen removal activity was inhibited by heat treatment and exposure to extreme pH (2.0) of bifidobacterial cell. NADH oxidase was major enzyme related to oxygen removal activity. Oxygen-tolerant bifidobacteria possessed high NADH peroxidase activity level to detoxify $H_2O_2$ formed from reaction of NADH oxidase. Addition of oxygen to anaerobic culture broth significantly increased activities of HADH oxidase and NADH peroxidase within 1hr and rapid increment of oxygen concentration was prevented. Results showed NADH oxidase and NADH peroxidase of oxygen-tolerant bifidobacteria played important roles in elimination of oxygen and oxygen metabolite $(H_2O_2)$.

• Journal of Microbiology and Biotechnology
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• v.27 no.4
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• pp.739-746
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• 2017

As alternatives to antibiotics in livestocks, probiotics have been used, although most of them in the form of liquid or semisolid formulations, which show low cell viability after oral administration. Therefore, suitable dry dosage forms should be developed for livestocks to protect probiotics against the low pH in the stomach such that the products have higher probiotics survivability. Here, in order to develop a dry dosage forms of probiotics for poultry, we used hydroxypropyl methylcellulose phthalate 55 (HPMCP 55) as a tablet-forming matrix to develop probiotics in a tablet form for poultry. Here, we made three different kinds of probiotics-loaded tablet under different compression forces and investigated their characteristics based on their survivability, morphology, disintegration time, and kinetics in simulated gastrointestinal fluid. The results indicated that the probiotics formulated in the tablets displayed higher survival rates in acidic gastric conditions than probiotics in solution. Rapid release of the probiotics from the tablets occurred in simulated intestinal fluid because of fast swelling of the tablets in neutral pH. As a matrix of tablet, HPMCP 55 provided good viability of probiotics after 6 months under refrigeration. Moreover, after oral administration of probiotics-loaded tablets to chicken, more viable probiotics were observed, than with solution type, through several digestive areas of chicken by the tablets.

• Journal of Pharmaceutical Investigation
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• v.35 no.6
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• pp.437-443
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• 2005

A rapid, selective and sensitive reversed-phase HPLC method for the determination of a major metabolite of terfenadine, fexofenadine, in human serum was developed, validated, and applied to the pharmacokinetic study of terfenadine. Fexofenadine and internal standard, haloperidol were extracted from human serum by liquid-liquid extraction with acetonitrile and analyzed on a $Symmetry^{TM}$ C8 column with the mobile phase of 1% triethylamine phosphate (pH 3.7)-acetonitrile (67:33, v/v, adjusted to pH 5.6 with triethylamine). Detection wavelength of 230 nm for excitation, 280 nm for emission and flow rate of 1.0 mL/min were fixed for the study. The assay robustness for the changes of mobile phase pH, organic solvent content, and flow rate was confirmed by $3^{3}$ factorial design using a fixed fexofenadine concentration (50 ng/mL) with respect to its peak area and retention time. In addition, the ruggedness of this method was investigated at three different laboratories using same quality control (QC) samples. This method showed linear response over the concentration range of 10-500 ng/mL with correlation coefficients greater than 0.999. The lower limit of quantification using 0.5 mL of serum was 10 ng/mL, which was sensitive enough for the pharmacokinetic studies of terfenadine. The overall accuracy of the quality control samples ranged from 95.70 to 114.58% for fexofenadine with overall precision (% C.V.) being 3.53-14.39%. The relative mean recovery of fexofenadine for human serum was 90.17%. Stability studies (freeze-thaw, short-term, extracted serum sample and stock solution) showed that fexofenadine was stable during storage, or during the assay procedure in human serum. However, the storage at $-70^{\circ}C$ for 4 weeks showed that fexofenadine was not stable. The peak area and retention time of fexofenadine were not significantly affected by the changes of mobile phase pH, organic solvent content, and flow rate under the conditions studied. This method showed good ruggedness (within 15% C.V.) and was successfully used for the analysis of fexofenadine in human serum samples for the pharmacokinetic studies of orally administered Tafedine tablet (60 mg as terfenadine) at three different laboratories, demonstrating the suitability of the method.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.21 no.2
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• pp.71-79
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• 1988

For the purpose of producing low salt fermented anchovy by accelerated method with a strong proteolytic bacteria, in this study, a strong proteolytic bacterium was isolated from low salt fermented anchovy and its bacteriological characteristics and properties of protease were experimented. The results obtained were as fellows : three proteolytic bacteria, Aeromonas anaerogenes Barillus subtilis and Staphylococcus saprophyticus were isolated from low salt fermented anchovy($4\%\;of\;salt,\;4\%\;of\;KCl,\;0.5\%\;of\;lactic\;acid,\;6\%$of sorbitol and $4\%$ of alcohol extract of red pepper) after 40 days fermentation. Among these strains, which grow best at $30^{\circ}C$, pH 7.0, B. subtilis was found the best proteolytic strain and benefit for industrial use as shown $0.95\;hr^{-1}$ of specific growth rate, $89{\mu}g-Tyr/hr.ml$ of maximum activity after 12 hrs culture in TPY broth. The protease produced by by B. subtilis showed maximum activity at $35^{\circ}C$, pH 7.0, and molecular weight was estimated to be 23,000 by Sephadex G-100 filtration, and it was supposed to be a kind of metal chelator sensitive neutral protease from the results of strong sensitivity against EDTA, o-phenanthroline and metal ions such as $Cu^{2+},\;Ni^{2+},\;Fe^{2+}.Km$ value of that by method of Lineweaver-Burk was determinded to be $0.73\%$ for casein as a substrate.

• IMMUNE NETWORK
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• v.2 no.1
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• pp.41-48
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• 2002

Background: Viral antigens presented on the cell surface in association with MHC class I molecules are recognized by CD8+ T cells. MHC restricted peptides are important in eliciting cellular immune responses. As peptide antigens have a weak immunigenicity, pH-sensitive liposomes were used for peptide delivery to induce effective cytotoxic T lymphocyte (CTL) responses. In the previous study, as the HBx peptides could induce specific CTLs in vitro, we tested whether the HLA-A2/$K^b$ transgenic mice that were immunized by HBx-derived peptides could be protected from a viral challenge. Methods: HBx-peptides encapsulated by pH-sensitive liposomes were prepared. $A2K^b$ transgenic mice were immunized i.m. on days one and seven with the indicated concentrations of liposome-encapsulated peptides. Three weeks later, mice were infected with $1{\times}10^7pfu$/head of recombinant vaccinia virus (rVV)-HBx via i.p. administration. The ovaries were extracted from the mice, and the presence of rVV-HBx in the ovaries was analyzed using human TK-143B cells. IFN-${\gamma}$ secretion by these cells was directly assessed using a peptide-pulsed target cell stimulation assay with either peptide-pulsed antigen presenting cells (APCs), concanavalin A ($2{\mu}g/ml$), or a vehicle. To generate peptide-specific CTLs, splenocytes obtained from the immunized mice were stimulated with $20{\mu}g/ml$ of each peptide and restimulated with peptide-pulsed APC four times. The cytotoxic activity of the CTLs was assessed by standard $^{51}Cr$-release assay and intracellular IFN-${\gamma}$ assay. Results: Immunization of these peptides as a mixture in pH-sensitive liposomes to transgenic mice induced a good protective effect from a viral challenge by inducing the peptide-specific CD8+ T cells. Mice immunized with $50{\mu}g/head$ were much better protected against viral challenge compared to those immunized with $5{\mu}g$/head, whereas the mice immunized with empty liposomes were not protected at all. After in vitro CTL culture by peptide stimulation, however, specific cytotoxicity was much higher in the CTLs from mice immunized with $5{\mu}g/head$ than $50{\mu}g/head$ group. Increase of the number of cells that intracellular IFN-${\gamma}$ secreting cell among CD8+ T cells showed similar result. Conclusion: Mice immunized with XEPs within pH-sensitive liposome were protected against viral challenge. The protective effect depended on the amount of antigen used during immunization. XEP-3-specific CTLs could be induced by peptide stimulation in vitro from splenocytes obtained from immunized mice. The cytotoxic effect of CTLs was measured by $^{51}Cr$-release assay and the percentage of accumulated intracellular IFN-${\gamma}$ secreting cells after in vitro restimulation was measured by flow cytometric analysis. The result of $^{51}Cr$-release cytotoxicity test was well correlated with that of the flow cytometric analysis. Viral protection was effective in immunized group of $50{\mu}g/head$, while in the in vitro restimulation, it showed more spectific response in $5{\mu}g$/head group.