• The Korean Journal of Pharmacology
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• v.32 no.3
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• pp.373-380
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• 1996

Recently we reported that GS 386, 1-(4'-methoxybenzyl)-6,7-dimethoxy-3,4-dihydroisoquinoline, inhibited amplitude of the $Ca^{2+}$ current by reducing the probability of $Ca^{2+}$ channel opening without changing channel kinetics in isolated rabbit atrial myocyte. In the present study, further investigation of the mechanism of action of GS 386 was performed using isolated rat trachealis. GS 386 concentration-dependently relaxed rat trachealis contracted by carbachol $(0.3{\mu}M)$ and high $K^+$(65.4 mM) with $IC_{50}$ 5.24 and 5.67 ${\mu}M$, respectively. Verapamil inhibited more effectively the high $K^+-contracted$ tissues than those with carbachol in the rat trachealis muscle. In $Ca^{2+}-free$ media, $Ca^{2+}-induced$ contraction was inhibited by GS 386. Furthermore, high concentration of GS 386 $(100{\mu}M)$ but not verapamil, attenuated a phasic contraction induced not only by carbachol but also caffeine, indicating that GS386 can enter into the cytoplasm where it may exert secondary actions on internal sites of the muscle, such as sarcoplasmic reticulum. Moreover, GS 386 showed verapamil-resistant component of relaxation and increased cAMP levels in rat trachal smooth muscle. These results suggest that the mechanism of action of GS 386 attributes to not only $Ca^{2+}$ antagonistic action but also weak phosphodiesterase inhibitory action.

• The Korean Journal of Pharmacology
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• v.30 no.1
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• pp.101-109
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• 1994

Pharmacological characterization of GS 283, a tetrahydroisoquinoline derivative has been elucidated using rat thoracic aorta, guinea pig tenea coli and rabbit mesentery artery in vitro. GS 283 showed calcium antagonistic action in vascular smooth muscle, since high $K^+-induced$ contraction was concentration dependently inhibited. GS 283 also inhibited the contraction induced by ${\alpha}_1$ receptor activation. Vasodilating action of GS 283 was not modified by the propranolol, indicating that GS 283 has no ${\beta}$ receptor stimulatory action. Simultaneous measurement of intracellular calcium change and muscle tension indicated that the inhibitory effect of GS 283 was accompanied by the increase in tissue fluorescence. This increment was not due to fura 2 fluorescence but to endogenous pyridine nucleotide, suggesting that GS 283 has an effect to inhibit mitochondrial function. GS 283 had an inhibitory action on cyclic AMP and GMP-dependent phosphodiesterases from rat brain with Ki values of 2.5 and 6.7 mM. From these findings we concluded that GS 283 has multiple action such as the inhibition of cyclic nucleotide-dependent phosphodiesterases, blocking of calcium channel as well as inhibition of mitochondrial function which are responsible for vasodilatation.

• Journal of Food Hygiene and Safety
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• v.19 no.3
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• pp.151-160
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• 2004

Enterococcus faecium MJ5-14 isolated from Meju produced a bacteriocin, which was antagonistic towards Listeria monocytogenes. Bacteriocin activity reached a maximum (640 BU/mL) after incubation for 12 hr, the early stationary phase, then dropped after the late stationary phase. Bacterocin of E. faecium MJ5-14 was extremely active against a wide range of Listeria species, including L. monocytogenes with sensitives up to about 640 BU/mL. In case of mixed culture with 105 CFU/mL L. monocytogenes and 105 CFU/mL E. faecium MJ5-14, the inhibitory effect against L. monocytogenes at $37^{\circ}C$ was higher than at $25^{\circ}C$. The mode of action was identified as bactericidal, because the addition of 100 BU/mL this bacteriocin to cell suspensions of L. monocytogenes KCTC 3569, led to a marked decrease in the number of viable cells. Further, when held in contact with bacteriocin of E. faecium MJ15-14 for 12 hr, L. monocytogenes KCTC 3569 displayed the disruption of the cells and an important efflux of the intracellular material.

• The Korean Journal of Physiology and Pharmacology
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• v.16 no.1
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• pp.37-42
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• 2012

The aim of the present study was to elucidate the direct effects of melatonin on bladder activity and to determine the mechanisms responsible for the detrusor activity of melatonin in the isolated rat bladder. We evaluated the effects of melatonin on the contractions induced by phenylephrine (PE), acetylcholine (ACh), bethanechol (BCh), KCl, and electrical field stimulation (EFS) in 20 detrusor smooth muscle samples from Sprague-Dawley rats. To determine the mechanisms underlying the inhibitory responses to melatonin, melatonin-pretreated muscle strips were exposed to a calcium channel antagonist (verapamil), three potassium channel blockers [tetraethyl ammonium (TEA), 4-aminopyridine (4-AP), and glibenclamide], a direct voltage-dependent calcium channel opener (Bay K 8644), and a specific calcium/calmodulin-dependent kinase II (CaMKII) inhibitor (KN-93). Melatonin pretreatment ($10^{-8}{\sim}10^{-6}M$) decreased the contractile responses induced by PE ($10^{-9}{\sim}10^{-4}M$) and Ach ($10^{-9}{\sim}10^{-4}M$) in a dose-dependent manner. Melatonin ($10^{-7}M$) also blocked contraction induced by high KCl ($[KCl]_{ECF}$; 35 mM, 70 mM, 105 mM, and 140 mM) and EFS. Melatonin ($10^{-7}M$) potentiated the relaxation response of the strips by verapamil, but other potassium channel blockers did not change melatonin activity. Melatonin pretreatment significantly decreased contractile responses induced by Bay K 8644 ($10^{-11}{\sim}10^{-7}M$). KN-93 enhanced melatonin-induced relaxation. The present results suggest that melatonin can inhibit bladder smooth muscle contraction through a voltage-dependent, calcium-antagonistic mechanism and through the inhibition of the calmodulin/CaMKII system.

• Journal of Microbiology and Biotechnology
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• v.30 no.7
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• pp.1027-1036
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• 2020

Stipa purpurea is a unique and dominant herbaceous plant species in the alpine steppe and meadows on the Qinghai-Tibet Plateau (QTP). In this work, we analyzed the composition and diversity of the culturable endophytic fungi in S. purpurea according to morphological and molecular identification. Then, we investigated the bioactivities of these fungi against plant pathogenic fungi and 1-aminocyclopropane-1-carboxylate deaminase (ACCD) deaminase activities. A total of 323 fungal isolates were first isolated from S. purpurea, and 33 fungal taxa were identified by internal transcribed spacer primers and grouped into Ascomycota. The diversity of endophytic fungi in S. purpurea was significantly higher in roots as compared to leaves. In addition, more than 40% of the endophytic fungi carried the gene encoding for the ACCD gene. The antibiosis assay demonstrated that 29, 35, 28, 37 and 34 isolates (43.9, 53.1, 42.4, 56.1, and 51.5%) were antagonistic to five plant pathogenic fungi, respectively. Our study provided the first assessment of the diversity of culture-depending endophytic fungi of S. purpurea, demonstrated the potential application of ACCD activity and antifungal activities with potential benefits to the host plant, and contributed to high biomass production and adaptation of S. purpurea to an adverse environment.

• The Korean Journal of Pesticide Science
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• v.10 no.1
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• pp.56-65
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• 2006

An antagonistic bacterial isolate, that inhibits the growth of plant pathogens, was selected and identified from 5,000 isolates screened from the rhizosphere of various crop plants. An isolate Bacillus sp. N32, tested against Colletotrichum gloeosporioides causing anthracnose disease in hot pepper, produced both a heat resistant antifungal protein and a heat sensitive antifungal protein. The heat resistant protein was partially purified by Ammonium sulfate fractionation and gel filtration chromatography. The bioautography showed that the proteins possessed high antifungal activity. The biosynthetic gene cluster responsible for the heat resistant antifungal protein was cloned from cosmid library using DNA probe obtained from PCR product with the primers targeting the conserved nucleotide sequence of the synthetic genes reported earlier, Most of the clones obtained showed higher homology to fengycin antibiotic synthetic gene family reported earlier. On the other hand, the heat sensitive protein was isolated from SDS-PAGE and electroblotting to determine the N-terminal amino acid sequences. The heat sensitive antifungal protein gene was cloned from the ${\lambda}-ZAP$ libraries using a DNA probe based on the N-terminal amino acid sequences of the heat sensitive protein. We are contemplating to clone and sequence the whole gene cluster encoding the heat sensitive protein for further analysis.

• Microbiology and Biotechnology Letters
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• v.34 no.4
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• pp.311-317
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• 2006

Using PCR amplification, we cloned a cellulase gene (ce/H) from the Bacillus subtilis AH18 which has plant growth-promoting activity and antagonistic ability against pepper blight caused by Phytophthora capsici. The 1.6 kb PCR fragment contained the full sequence of the cellulase gene and the 1,582 bp gene deduced a 508 amino acid sequence. Similarity search in protein database revealed that the cellulase of B. subtilis AH18 was more than 98% homologous in the amino acid sequence to those of several major Bacillus spp. The ce/H was expressed in E. coli under an IPTG inducible lac promoter on the vector, had apparent molecular weight of about 55 kDa upon CMC-SDS-PAGE analysis. Partially purified cellulase had not only cellulolytic activity toward carboxymethyl-cellulose (CMC) but also insoluble cellulose, such as Avicel and filter paper (Whatman No. 1). In addition, the cellulase could degrade a fungal cell wall of Phytophthora capsici. The optimum pH and temperature of the ce/H coded cellulase were determined to be pH 5.0 and $50^{\circ}C$. The enzyme activity was activated by $AgNO_3$ or $CoCl_2$. However its activity was Inhibited by $HgC1_2$. The enzyme activity was activated by hydroxy urea or sodium azide and inhibited by CDTA or EDTA. The results indicate that the cellulase gene, ce/H is an antifungal mechanism of B. subtilis AH18 against phytophthora blight disease in red-pepper.

• Microbiology and Biotechnology Letters
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• v.36 no.2
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• pp.106-114
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• 2008

One bacterium, which showed strong antagonistic activity against H. pylori KCCM 41756, was isolated from kimchi. The strain NO1 was designated as Lactobacillus plantarum NO1 based on Gram staining, biochemical properties, and 16S rRNA gene sequencing. The culture medium $(2{\sim}4{\mu}g/ml)$ of Lb. plantarum NO1 reduced $(40{\sim}60%)$ the urease activity of H. pylori KCCM 41756. Lb. plantarum NO1 inhibited the binding of H. pylori to human gastric cancer cell line, AGS cells, by more than 33%. Lb. plantarum NO1 exhibited high viability (maintained initial viable cell count of $10^9CFU/ml$) in 0.05 M sodium phosphate buffer (pH 3.0) for 2 h, in artificial gastricjuice for 2 h and in 0.3%, 0.5% oxgall for 24 h. Hemolysis phenomena did not observed when Lb. plantarum NO1 was incubated in the blood agar media. We concluded that Lb. plantarum NO1 can be a good candidate as a probiotic, harboring anti-H. pylori activity.

• The Korean Journal of Physiology and Pharmacology
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• v.4 no.3
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• pp.185-195
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• 2000

Vascular diseases are significant complications of diabetes mellitus (DM), and the endothelial cells may play a pivotal role in the development of vascular disease in DM. Endothelin-1 (ET-1) released from endothelium is a potent vasoconstrictor peptide and circulating level of ET-1 is increased in a variety of disease states. The purpose of this study was to determine the changes of responsiveness to ET-1 in DM, and we experimented on the changes in the ET-1-induced contraction, levels of nitrite and lipid peroxidation, and ET-1 immunoreactivity in aorta from streptozotocin-induced DM rats. DM was induced by single injection of streptozotocin (55 mg/kg, i.p.). The immunoreactive ET-1 levels in endothelial layer of thoracic aorta were much higher in DM rats than control rats. Nitrite in tissue homogenate was decreased and plasma nitrite was increased in DM rats. Malondialdehyde (MDA) was significantly increased in DM rats and cGMP was not significantly different between control and DM rats. ET-1 produced concentration- dependent contractile responses that are significantly attenuated in DM rats compared to controls. In the presence of selective $ET_A$ receptor antagonist BQ610, the maximum contraction was decreased and the concentration ratios for BQ610 yielded $pA_2$ values of 7.3 (slope, 0.65) in control rats, whereas BQ610 had no antagonistic effect on ET-1-induced contraction in DM rats. However, pretreatment with BQ788, an $ET_B$ receptor antagonist, maximum response was decreased and the dose-response curves for ET-1 were shifted to the right in both groups and $pA_2$ values were 7.9 and 7.7 (slope, 1.05 in control and DM rats), respectively. IRL 1620 and sarafotoxin S6c, $ET_B$ agonists, induced relaxation in control rats but not in DM rats. These results indicate that endothelial cell dysfunction and enhanced immunoreactivity of ET-1 have been found in DM rat and ET-1-induced contraction was attenuated in DM rat. These attenuated responses might be at least in part caused by the alteration of $ET_A$ receptor properties (e.g. desensitization), and partly related with an alteration in intracellular mechanism for contraction to ET-1.

• Journal of Labour Economics
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• v.27 no.1
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• pp.27-53
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• 2004

This paper analyzes the two cases of labor disputes (Hyundai Motor in 1998 and Power Generation Companies in 2002) in the period of restructuring, by applying the behavioral theory of labor negotiations as a comparative framework. The paper compares th backgrounds of the labor disputes, core issues, bargaining processes, and evolutionary patterns and consequences of the labor disputes at the two cases. The common features, found in the two dispute cases, are strong mistrust and exclusive bargaining attitude between labor unions and management, little feasibility of contract zone in bargaining proposals by the two parties, heteronomous dispute resolution by the intervention of the government, and the lack of learning effect gained from the experience of labor disputes. This comparative case study identifies that the confrontational labor-management relations at the firm level is re-produced by a regressive process of the following circulation: labor-management distrust $\rightarrow$ interest conflict in bargaining demand $\rightarrow$ exclusive bargaining attitude $\rightarrow$ the experience of antagonistic dispute $\rightarrow$ deepened distrust. In conclusion, four parties-labor unions, management, the government, and public press - are required to make much effort to replace the vicious circle of labor-management confrontation by a virtueous cycle of labor-management cooperation.