• Biomolecules & Therapeutics
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• v.12 no.3
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• pp.165-174
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• 2004

The aim of the present study was to investigate the effect of FCCP (carbonyl cyanide p-trifluoromethoxyphenyIhydrazone), which is a potent mitochondrial uncoupler, on secretion of catecholamines (CA) from the perfused model of the rat adrenal gland and to establish the mechanism of its action. The perfusion of FCCP (3 ${\times}$ $10^{-5}$ M) into an adrenal vein of for 90 min resulted in great increases in CA secretions. Tachyphylaxis to CA-releasing effect of FCCP was not observed by repeated perfusion of it. The CA-releasing effects of FCCP were depressed by pre-treatment with pirenzepine, chlorisondamine, nicardipine, TMB-8, and the perfusion of EGTA plus $Ca^{2+}$-free medium. In the presence of FCCP (3 ${\times}$ $10^{-5}$ M), the CA secretory responses induced by Ach (5.32 ${\times}$ $10^{-3}$ M), and DMPP ($10^{-4}$ M) were significantly enhanced. Furthermore, the perfusion of CCCP (3 ${\times}$ $10^{-5}$ M), a similar mitochondrial uncoupler, into an adrenal vein for 90 min also caused an increased response in CA secretion. Taken together these experimental results indicate that FCCP causes the CA secretion the perfused rat adrenal medulla in a calcium-dependent fashion. It is suggested that this facilitatory effects of FCCP may be mediated by cholinergic receptor stimulation, which is relevant to both stimulation of the $Ca^{2+}$ influx and $Ca^{2+}$ release from cytoplasmic $Ca^{2+}$ stores.

• Biomolecules & Therapeutics
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• v.15 no.3
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• pp.137-144
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• 2007

Although lovastatin, a competitive inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A (HMGCoA) reductase, has been shown to have anti-cancer actions, the effect on human hepatoma cells was not investigated. Moreover, the exact mechanism of this action is not fully understood. In this study we investigated the mechanism by which lovastatin induces apoptosis using HepG2 human hepatoblastoma cells. Lovastatin induced apoptotic cell death in a dose-dependent manner in the cells, assessed by the flow cytometric analysis. Treatment with mevalonic acid, a precursor of cholesterol, did not significantly suppress the lovastatin-induced apoptosis. Lovastatin induced a rapid and sustained increase in intracellular $Ca^{2+}$ concentration. Treatment with EGTA, an extracellular $Ca^{2+}$ chelator did not significantly alter the lovastatin-induced intracellular $Ca^{2+}$ increase and apoptosis, whereas intracellular $Ca^{2+}$ reduction with BAPTA/AM and intracellular $Ca^{2+}$ release blockers (dantrolene and TMB-8) completely blocked these actions of lovastatin. In addition, the lovastatin-induced apoptosis was significantly reduced by a calpain inhibitor, a broad spectrum caspase inhibitor z-VAD-fmk and inhibitors specific for caspase-9 and caspase-3 (z-LEHD-fmk and z-DEVD-fmk, respectively), but not by an inhibitor specific for caspase-8 (z-IETD-fmk). Collectively, these results suggest that lovastatin induced apoptosis of HepG2 hepatoma cells through intracellular $Ca^{2+}$ release and calpain activation, leading to triggering mitochondrial apoptotic pathway. These results further suggest that lovastatin may be valuable for the therapeutic management of human hepatoma.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.4
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• pp.443-454
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• 1998

The present study was attempted to investigate the effect of vasoactive intestinal polypeptide (VIP) on secretion of catecholamines (CA) and to establish whether there is the existence of a noncholinergic mechanism in adrenomedullary CA secretion from the isolated perfused rat adrenal gland. The perfusion into an adrenal vein of VIP $(3{\times}10^{-6}\;M)$ for 5 min or the injection of acetylcholine (ACh, $5.32{\times}10^{-3}\;M$) resulted in great increases in CA secretion. Tachyphylaxis to releasing effect of CA evoked by VIP was not observed by the repeated perfusion. The net increase in adrenal CA secretion evoked by VIP still remained unaffected in the presence of atropine or chlorisondamine. However, the CA release in response to ACh was greatly inhibited by the pretreatment with atropine or chlorisondamine. The releasing effects of CA evoked by either VIP or ACh were depressed by pretreatment with nicardipine, TMB-8, and the perfusion of $Ca^{2+}$-free medium. Moreover, VIP- as well as ACh-evoked CA secretory responses were markedly inhibited under the presence of $(Lys^1,\;Pro^{2.5},\;Arg^{3.4},\;Tyr^6)-VIP$ or naloxone. CA secretory responses induced by ACh and high $K^+\;(5.6{\times}10^{-2}\;M)$ were potentiated by infusion of VIP $(3{\times}10^{-6}M\;for\;5\;min)$. Taken together, these experimental results indicate that VIP causes CA release in a fashion of calcium ion -dependence, suggesting strongly that there exists a noncholinergic mechanism that may be involved in the regulation of adrenomedullary CA secretion through VIP receptors in the rat adrenal gland, and that VIP may be the noncholinergic excitatory secretagogue present in the chromaffin cells.

• Korean Journal of Materials Research
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• v.28 no.5
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• pp.301-307
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• 2018

A boron-doped diamond(BDD) electrode is attractive for many electrochemical applications due to its distinctive properties: an extremely wide potential window in aqueous and non-aqueous electrolytes, a very low and stable background current and a high resistance to surface fouling. An Ar gas mixture of $H_2$, $CH_4$ and trimethylboron (TMB, 0.1 % $C_3H_9B$ in $H_2$) is used in a hot filament chemical vapor deposition(HFCVD) reactor. The effect of argon addition on quality, structure and electrochemical property is investigated by scanning electron microscope(SEM), X-ray diffraction(XRD) and cyclic voltammetry(CV). In this study, BDD electrodes are manufactured using different $Ar/CH_4$ ratios ($Ar/CH_4$ = 0, 1, 2 and 4). The results of this study show that the diamond grain size decreases with increasing $Ar/CH_4$ ratios. On the other hand, the samples with an $Ar/CH_4$ ratio above 5 fail to produce a BDD electrode. In addition, the BDD electrodes manufactured by introducing different $Ar/CH_4$ ratios result in the most inclined to (111) preferential growth when the $Ar/CH_4$ ratio is 2. It is also noted that the electrochemical properties of the BDD electrode improve with the process of adding argon.

• Journal of Microbiology and Biotechnology
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• v.22 no.3
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• pp.311-315
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• 2012

A novel ${\beta}$-proteobacterium, designated BXN5-$27^T$, was isolated from soil of a ginseng field of Baekdu Mountain in China, and was characterized using a polyphasic approach. The strain was Gram-staining-negative, aerobic, motile, non-spore-forming, and rod shaped. Strain BXN5-$27^T$ exhibited ${\beta}$-glucosidase activity that was responsible for its ability to transform ginsenoside $Rb_1$ (one of the dominant active components of ginseng) to compound Rd. Phylogenetic analysis based on 16S rRNA gene sequences showed that this strain belonged to the family Comamonadaceae; it was most closely related to Ramlibacter henchirensis $TMB834^T$ and Ramlibacter tataouinensis$TTB310^T$ (96.4% and 96.3% similarity, respectively). The G+C content of the genomic DNA was 68.1%. The major menaquinone was Q-8. The major fatty acids were $C_{16:0}$, summed feature 4 (comprising $C_{16:1}$ ${\omega}7c$ and/or iso-$C_{15:0}$ 2OH), and $C_{17:0}$ cyclo. Genomic and chemotaxonomic data supported the affiliation of strain BXN5-$27^T$ to the genus Ramlibacter. However, physiological and biochemical tests differentiated it phenotypically from the other established species of Ramlibacter. Therefore, the isolate represents a novel species, for which the name Ramlibacter ginsenosidimutans sp. nov. is proposed, with the type strain being BXN5-$27^T$ (=DSM $23480^T$ = LMG $24525^T$ = KCTC $22276^T$).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.4
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• pp.376-382
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• 2018

We investigated the effect of replacing tuna byproduct meal (TBM) and rice bran (RB) with fish meal (FM) and macroalgae (MA) in extruded pellets (EP) supplied as a diet to juvenile Abalone Haliotis duscus in aquaculture. In total, 80,000 juvenile abalone were distributed among eight indoor raceways and supplied with one of four experimental diets. The control diet consisted of FM, fermented soybean meal, corn gluten meal and shrimp meal as protein sources, with wheat flour and dextrin as carbohydrate sources; the control diet also contained MA. In the FM50 diet, TBM was replaced with 50% FM. In the MA 50 diet, RB was replaced with 50% MA. The final diet, FM50+MA50, included TMB and RB in place of 50% FM and 50% MA. Abalone were fed to satiation with little food leftover for 16 weeks. Weight gain and specific growth rate of abalone fed the control diet were greater than those of abalone fed the FM50 and MA50 diets, but not different from those of abalone fed FM50+MA50 diet. The proximate composition of abalone soft body did not vary according to experimental diets. Based on these results, it appears that the traditional commercial diet for juvenile abalone, comprising FM and MA, could be replaced with one containing 50% TBM and 50% RB without any retardation of growth.

• YAKHAK HOEJI
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• v.57 no.1
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• pp.24-31
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• 2013

Although statins, inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, have been shown to increase melanin synthesis, the exact mechanism of this action is not fully understood. In this study we investigated the possible involvement of intracellular $Ca^{2+}$ signal in the mechanism of stimulation of melanin synthesis induced by lovastatin in B16 cells. Lovastatin stimulated the production of melanin in a dose-dependent manner in the cells. Treatment with mevalonate, FPP and GGPP, precursors of cholesterol, did not significantly suppress the lovastatin-induced melanin production, suggesting that inhibition of cholesterol synthesis may not be involved in the mechanism of the action of lovastatin. In addition, lovastatin did not significantly alter the cAMP concentration and the stimulated production of melanin by lovastatin was not significantly changed by treatment with H89, a potent inhibitor of protein kinase A, which demonstrates that cAMP pathway may not be involved. However, lovastatin increased intracellular $Ca^{2+}$ concentration in a dose-related fashion. Treatment with EGTA, an extracellular $Ca^{2+}$ chelator did not significantly alter the lovastatin-induced intracellular $Ca^{2+}$ increase and melanin synthesis, whereas intracellular $Ca^{2+}$ reduction with BAPTA/AM and intracellular $Ca^{2+}$ release blockers (dantrolene and TMB-8) completely blunted these actions of lovastatin. Taken together, these results suggest that the intracellular $Ca^{2+}$ release may play an important role in the lovastatin-induced stimulation of melanin synthesis in B16 cells. These results further suggest that lovastatin may be useful for the treatment of hypopigmentation disorders, such as vitiligo.

• Journal of Microbiology and Biotechnology
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• v.31 no.5
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• pp.705-709
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• 2021

Porphyromonas gingivalis (P. gingivalis) is a major bacterial pathogen that causes periodontitis, a chronic inflammatory disease of tissues around the teeth. Periodontitis is known to be related to other diseases, such as oral cancer, Alzheimer's disease, and rheumatism. Thus, a precise and sensitive test to detect P. gingivalis is necessary for the early diagnosis of periodontitis. The objective of this study was to optimize a rapid visual detection system for P. gingivalis. First, we performed a visual membrane immunoassay using 3,3',5,5'-tetramethylbenzidine (TMB; blue) and coating and detection antibodies that could bind to the host laboratory strain, ATCC 33277. Antibodies against the P. gingivalis surface adhesion molecules RgpB (arginine proteinase) and Kgp (lysine proteinase) were determined to be the most specific coating and detection antibodies, respectively. Using these two selected antibodies, the streptavidin-horseradish peroxidase (HRP) reaction was performed using a nitrocellulose membrane and visualized with a detection range of 10³-10⁵ bacterial cells/ml following incubation for 15 min. These selected conditions were applied to test other oral bacteria, and the results showed that P. gingivalis could be detected without cross-reactivity to other bacteria, including Streptococcus mutans and Escherichia fergusonii. Furthermore, three clinical strains of P. gingivalis, KCOM 2880, KCOM 2803, and KCOM 3190, were also recognized using this optimized enzyme immunoassay (EIA) system. To conclude, we established optimized conditions for P. gingivalis detection with specificity, accuracy, and sensitivity. These results could be utilized to manufacture economical and rapid detection kits for P. gingivalis.

• Geomechanics and Engineering
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• v.29 no.3
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• pp.311-320
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• 2022

TBM concrete segment requires a higher level of material properties compared to general concrete structures due to difficulties in maintenance and uncertainty in ground conditions. In this regard, recently, as one of the methods to achieve enhancement effect on concrete strength, many researchers have been focusing on adding CNTs to concrete mixture. However, even CNTs do not compensate the weakness that concrete exhibits brittle behavior after cracking. Separately, over the past few decades, a number of studies have been conducted on fiber reinforced concrete which exhibits ductile behavior due to fibers bridging cracks. However, only limited studies have been conducted to employ the advantages of the both materials together. In this study, an experimental program has been conducted to investigate the effect of CNTs on the workability and the compressive behavior of PVA-ECC which exhibits ductile tensile behavior with well-distributed cracks even without a conventional rebar. In addition to the compression test, SEM analysis has been also conducted for detailed investigation in the microstructure. The variable was the CNTs mix ratio, which were set to 0.00, 0.25, and 0.50 wt.% to the binding materials. It was observed though the test results that as the CNTs mix ratio increased, the workability considerably decreased with the reduced slump and slump flow. From the compression test results, it was also investigated that the compressive behavior was improved since the compressive strength, the strain corresponding to the compressive strength, and the modulus of elasticity increased with an increase of CNTs mix ratio. The contents of this paper will be useful for relevant research areas such as fiber reinforced concrete with CNTs which might be applied for high performance TMB concrete segments.

• Korean Journal of Clinical Laboratory Science
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• v.49 no.3
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• pp.220-226
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• 2017

Dopamine (DA) and serotonin (5-Hydroxytryptamine, 5-HT) are neurotransmitters and hormones that exist in small amounts but have important role in the body. Serum and 24-hour urine are used as specimens, and are usually examined by HPLC-MS. In this study, we tried to detect DA and 5-HT by competitive ELISA using antigen-antibody (Ab) reaction. After immobilizing $5{\mu}g/mL$ BSA conjugate on a 96-well surface, hormone and primary Ab, which are respectively diluted to different concentrations, were treated. Then, HRP-conjugated secondary Ab and TMB were added to measure absorbance. The regression equation and $R^2$ value were calculated based on absorbance, and sensitivity of Ab to hormone as well as the correlation between hormone concentration and absorbance were determined. In DA ELISA, $R^2$, the correlation between the concentration of hormone and absorbance, was the highest by 0.91 when anti-dopamine Ab was diluted 6,000 times and 7,000 times. In 5-HT ELISA, $R^2$ was bigger than 0.90 in every concentration except 3,000 times and 6,000 times. Both DA and 5-HT were not effectively detected at low concentrations (less than $1.0{\times}10^{-7}M$); and because reference value of serum DA is lower than this, HPLC-MS was required to detect serum DA. However, competitive ELISA may be effective in detecting 24-hour urine DA, serum, and 24-hour 5-HT. Further studies are needed to detect hormones more accurately at lower concentrations.