• Journal of Plant Biology
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• v.38 no.1
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• pp.87-93
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• 1995

For understanding physiological nature of phototaxis in Synechocystis sp. PCC 6803 PTX(S. 6803 PTX), we examined the effects of some metabolic inhibitors and cation ionophore on the phototactic movement. In the presence of DCMU, which blocks the photosynthetic electron transport just after photosystem II acceptor, there was no inhibitory effect on the phototaxis up to $100\;\mu\textrm{M}$. Instead, the respiratory electron chain inhibitor such as sodium azide dramatically impaired the phototaxis in S. 6803 PTX. These observations indicate that the phototaxis is linked not to photo-phosphorylation, but to respiratory phosphorylation. When the cells were treated with un couplers such as CCCP or DNP, which dissipate the electrochemical gradient of proton($\Delta\mu_{H}+$) across the cytoplasmic membrane, these chemicals did not affect phototaxis. In contrast, when cells were treated with DCCD or NBD which deprive cells of A TP but leave $\Delta\mu_{H}+$ intact across the membrane, the phototactic movement was severly reduced. These results imply that ATP production, not proton motive force, is involved in the phototactic movement in this organism as a driving motive force. The application of specific calcium ionophore A23187 strongly impaired positive phototaxis. Calcium fluxes should be engaged in the sensory trans-duction of phototactic orientation. Finally, when ethionine was supplimented to culture media, the photomovement of this organism was inhibited. This implies that methylation/demethylation mechanism controls the process of phototaxis in S. 6803 PTX like chemotaxis in E. coli and Salmonella typhimurium.murium.

• Journal of Pharmacopuncture
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• v.16 no.1
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• pp.43-49
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• 2013

Objective: Pyungwi-san (PWS) plays a role in a number of physiologic and pharmacologic functions in many organs. Interstitial cells of Cajal (ICCs) are pacemaker cells that generate slow waves in the gastrointestinal (GI) tract. We aimed to investigate the beneficial effects of PWS in mouse small-intestinal ICCs. Methods: Enzymatic digestion was used to dissociate ICCs from the small intestine of a mouse. The whole-cell patch-clamp configuration was used to record membrane potentials from the cultured ICCs. Results: ICCs generated pacemaker potentials in the GI tract. PWS produced membrane depolarization in the current clamp mode. Pretreatment with a $Ca^{2+}$-free solution and a thapsigargin, a $Ca^{2+}$-ATPase, inhibitor in the endoplasmic reticulum, eliminated the generation of pacemaker potentials. However, only when the thapsigargin was applied in a bath solution, the membrane depolarization was not produced by PWS. Furthermore, the membrane depolarizations due to PWS were inhibited not by U-73122, an active phospholipase C inhibitor, but by chelerythrine and calphostin C, protein kinase C inhibitors. Conclusions: These results suggest that PWS might affect GI motility by modulating the pacemaker activity in the ICCs.

• Korean Journal of Pharmacognosy
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• v.35 no.3 s.138
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• pp.250-254
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• 2004

Helicobacter pylori (H. pyroli) infection it associated with type B gastritis, peptic uler disease, and gastric cancer. The vacuolation of cells induced by H. pylori is thought to be essential for the initiation and maintenance of gastric infection. The roles of H. pylori cytotoxin, urease, and ammonia in the vacuolation of HeLa cells were determined. H. pylori toxin induced vacuolation of HeLa cells. Korean and Japanese radishes significantly prevented the vacuolation of HeLa cells induced by H. pylori toxin. The urease activity in vacuolated cells was also decreased with Korean and Japanese radishes. H. Pylori toxin-induced vacuolation was inhibited by vacuolar type ATPase inhibitors (bafilomycin and N-ethylmaleimide). However, further investigation is required to determine the mechanisms of radish for the inhibition of vacuole formation of eukaryotic cells in response to the H. pylori toxin.

• Molecules and Cells
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• v.27 no.3
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• pp.307-312
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• 2009

The interstitial cells of Cajal (ICC) are pacemaking cells required for gastrointestinal motility. The possibility of whether DA-9701, a novel prokinetic agent formulated with Pharbitis Semen and Corydalis Tuber, modulates pacemaker activities in the ICC was tested using the whole cell patch clamp technique. DA-9701 produced membrane depolarization and increased tonic inward pacemaker currents in the voltage-clamp mode. The application of flufenamic acid, a non-selective cation channel blocker, but not niflumic acid, abolished the generation of pacemaker currents induced by DA-9701. Pretreatment with a $Ca^{2+}$-free solution and thapsigargin, a $Ca^{2+}$-ATPase inhibitor in the endoplasmic reticulum, abolished the generation of pacemaker currents. In addition, the tonic inward currents were inhibited by U-73122, an active phospholipase C inhibitor, but not by $GDP-{\beta}-S$, which permanently binds G-binding proteins. Furthermore, the protein kinase C inhibitors, chelerythrine and calphostin C, did not block the DA-9701-induced pacemaker currents. These results suggest that DA-9701 might affect gastrointestinal motility by the modulation of pacemaker activity in the ICC, and the activation is associated with the non-selective cationic channels via external $Ca^{2+}$ influx, phospholipase C activation, and $Ca^{2+}$ release from internal storage in a G protein-independent and protein kinase C-independent manner.

• The Korean Journal of Physiology and Pharmacology
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• v.12 no.1
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• pp.25-30
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• 2008

Although many studies show that thromboxane $A_2\;(TXA_2)$ has the action of gastrointestinal (GI) motility using GI muscle cells and tissue, there are no reports on the effects of $TXA_2$ on interstitial cells of Cajal (ICC) that function as pacemaker cells in GI tract. So, we studied the modulation of pacemaker activities by $TXA_2$ in ICC with whole cell patch-clamp technique. Externally applied $TXA_2\;(5{\mu}M)$ produced membrane depolarization in current-clamp mode and increased tonic inward pacemaker currents in voltage-clamp mode. The tonic inward currents by $TXA_2$ were inhibited by intracellular application of GDP-${\beta}$-S. The pretreatment of ICC with $Ca^{2+}$ free solution and thapsigargin, a $Ca^{2+}$-ATPase inhibitor in endoplasmic reticulum, abolished the generation of pacemaker currents and suppressed the $TXA_2$-induced tonic inward currents. However, chelerythrine or calphostin C, protein kinase C inhibitors, did not block the $TXA_2$-induced effects on pacemaker currents. These results suggest that $TXA_2$ can regulate intestinal motility through the modulation of ICC pacemaker activities. This modulation of pacemaker activities by $TXA_2$ may occur by the activation of G protein and PKC independent pathway via extra and intracellular $Ca^{2+}$ modulation.

• Journal of Digestive Cancer Research
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• v.4 no.1
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• pp.1-9
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• 2016

The abundance of multi-drug resistance ATPase binding cassette and deranged self-renewal pathways shown in cancer stem cells (CSCs) played a crucial role in tumorigenesis, tumor resistance, tumor recurrence, and tumor metastasis. Therefore, elucidation of CSCs biology can improve diagnosis, enable targeted treatment, and guide the follow up of GI cancer patients. In order to achieve chemoquiescence, seizing cancer through complete ablation of CSCs, CSCs are rational targets for the design of interventions that will enhance responsiveness to traditional therapeutic strategies and contribute in the prevention of local recurrence as well as metastasis. However, current cancer treatment strategies fail to either detect or differentiate the CSCs from their non-tumorigenic progenies mostly due to the absence of specific biomarkers and potent agents to kill CSCs. Recent advances in knowledge of CSCs enable to produce several candidates to ablate CSCs in gastrointestinal (GI) cancers, especially cancers originated from inflammation-driven mutagenesis such as Barrett's esophagus (BE), Helicobacter pylori-associated gastric cancer, and colitis-associated cancer (CAC). Our research teams elucidated through revisiting old drugs that proton pump inhibitor (PPI) and potassium competitive acid blocker (p-CAB) beyond authentic acid suppression, chloroquine for autophage inhibition, sonic hedgehog (SHH) inhibitors, and Wnt/β-catenin/NOTCH inhibitor can ablate CSCs specifically and efficiently. Furthermore, nanoformulations of these molecules could provide an additional advantage for more selective targeting of the pathways existing in CSCs just like current molecular targeted therapeutics and sustained action, while normal stem cells intact. In this review article, the novel approach specifically to ablate CSCs existing in GI cancers will be introduced with the introduction of explored mode of action.

• Journal of Plant Biology
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• v.35 no.2
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• pp.107-116
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• 1992

The roles of RNA- and protein-synthesis and $H^{+}$ excretion in 1AA ($10\;\mu\textrm{M}$)-induced elongation were investigated using abraded hypocotyl segments of sunflower (Helianthus annuus L.). The response of elongation initiated about 13 min after IAA treatment. Removal of cuticle, acting as diffusion barrier for inhibitors, by mechanical abrasion of hypocotyl segments enhanced the effect of inhibitors markedly, but the degree of abrasion for the saturated effect of inhibition was different among inhibitors. The elongation induced by 1M was completely inhibited when cycloheximide ($10\;\mu\textrm{M}$) was applied to abraded hypocotyl segments as shortly as 4 min before the onset of the growth response (= 10 min after administration of IAA). Cordycepin ($200\;\mu\textrm{M}$) prevented completely 1AA-induced elongation when applied as shortly as 19 min before the onset of the growth response (=5 min before administration of 1AA). Vanadate (1 mM) inhibited both lAA-induced elongation and medium acidification via lAA-induced $H^{+}$ excretion to apoplast. Cycloheximide and cordycepin also prevented lAA-induced $H^{+}$ excretion strongly. However, inhibition by cycloheximide of lAA-induced elongation was not alleviated by acidifying the cell wall to pH 4.5. The results indicate that, a few minutes before the initiation of growih, protein synthesis is demanded for the initiation of 1AA-induced elongation and the $H^{+}$ excretion to cell wall, and that the H+ excretion, even though it may be necessary for elongation, does not seem to bring about acid growth simply through acidifying cell wall.l wall.

• Korean Journal of Pharmacognosy
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• v.47 no.2
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• pp.122-127
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• 2016

Methicillin-Resistant Staphylococcus aureus(MRSA) is a multidrug-resistant(MDR) strain. (+)-Usnic acid(UA) is uniquely found in lichens, and is especially abundant in genera such as Usnea and Cladonia. UA has antimicrobial activity against human and plant pathogens. Therefore, UA may be a good antibacterial drug candidate for clinical development. In search of a natural products capable of inhibiting this multidrug-resistant bacteria, we have investigated the antimicrobial activity of UA against 17 different strains of the bacterium. In this study, the effects of a combination of UA and permeable agents against MRSA were investigated. For the measurement of cell wall permeability, UA with concentration of Ethylenediaminetetraacetic acid(EDTA) was used. In the other hand, Sodium azide($NaN_3$) was used as inhibitors of ATPase. Against the 17 strains, the minimum inhibitory concentrations(MICs) of UA were in the range of $7.81-31.25{\mu}g/ml$. EDTA or $NaN_3$ cooperation against MRSA showed synergistic activity on cell wall. UA and in combination with EDTA and $NaN_3$ could lead to the development of new combination antibiotics against MRSA infection.

• Parasites, Hosts and Diseases
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• v.27 no.3
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• pp.161-170
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• 1989

The proteases of Toxoplasma gcndii were purified partially and characterisrd for some biochemical properties including various chromatographic patterns, major catalytic classes, and conditions to promote the activity of these enzymes. When Toxoplasma extract was incubated with 3H-casein at various pH, peak hydrolysis of casein was observed at pH 6.0 and at pH 8.5. Proteasfs working at pH 6.0 and at pH 8.5 were purified partially by conventional methods of chromatographies of DE52 anion rxchange, Sephadex G-200 gel permeation, and hydroxylapatite chromatography. Partially purified enzymes were tested by site-specific inhibitors and promotorf. The protease working at pH 6.0 was inactivated by iodoacetamide with LDso of 10-5 M and promoted by dithiothreitol, while the protease working at pH 8.5 was inhibited by phenylmethylsulfonyl fluoride with LD50 of 10-5 M and was Promoted by ATP (excess ATP beyond 2 mM inhibited the activity reversely). The protease of pH 8.5 had the activity of ATPase which might exert the energy to its action. Therefore the former was referred to as a cysteinyl acid protease and the latter, ATP-dependent neutral serine protease.