• Animal cells and systems
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• v.15 no.2
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• pp.123-130
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• 2011

Transient receptor potential melastatin 7 (TRPM7) channels are novel $Ca^{2+}$-permeable non-selective cation channels that are ubiquitously expressed. Activation of TRPM7 channels has been shown to be involved in the survival of gastric cancer cells. Here we show evidence suggesting that TRPM7 channels play an important role in $Zn^{2+}$- mediated cellular injury. Using a combination of electrophysiology, pharmacological analysis, small interfering RNA (siRNA) methods and cell death assays, we showed that activation of TRPM7 channels augmented $Zn^{2+}$-induced apoptosis of AGS cells, the most common human gastric adenocarcinoma cell line. The $Zn^{2+}$-mediated cytotoxicity was inhibited by the non-specific TRPM7 blockers $Gd^{3+}$ or 2 aminoethoxydiphenyl borate (2-APB) and TRPM7 specific siRNA. In addition, we showed that overexpression of TRPM7 channels in HEK293 cells increased $Zn^{2+}$- induced cell injury. Thus, TRPM7 channels may represent a novel target for physiological disorders where $Zn^{2+}$ toxicity plays an important role.

• Biomedical Science Letters
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• v.13 no.4
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• pp.333-339
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• 2007

Recently, much attention has been paid to human retinoblastoma since it provide a good model system for studying mechanisms underlying cell growth, differentiation, proliferation, and apoptosis, and for developing cancer therapy. However, until now it is unclear whether purinergic receptors are involved in the calcium mobilization in the retinoblastoma cells. In this regard, we measured possible purinergic signaling in WERI-Rb-1 cells using $Ca^{2+}$ imaging technique and RT-PCR method. ATP-induced $[Ca^{2+}]_i$ transients was maintained to about $90.7{\pm}1.0%$ of the control (n=48) even in the absence of extracellular calcium. The ATP-induced intracellular calcium response was only attained to $10.4{\pm}1.8%$ (n=55) of peak amplitude of the control after preincubation of 1 ${\mu}MU-73122$, a PLC inhibitor, but it was not affected by 1 ${\mu}MU-73343$, a inactive form of U-73122. And also ATP-induced $[Ca^{2+}]_i$ rise was almost attenuated by 20 ${\mu}M$ 2-APB, a putative $IP_3$ receptor inhibitor. Two subtypes of $IP_3$ receptor $(IP_{3-1}R,\;IP_{3-2}R)$ were identified by a RT-PCR method. These findings suggest that purinergic stimuli can cause calcium mobilization via $PLC-IP_3$ pathway after the activation of P2Y receptors in the retinoblastoma cells, which may play important roles in cell proliferation, differentiation, growth, and cell death.

• Korean Journal of Materials Research
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• v.26 no.1
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• pp.13-16
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• 2016

Morphology and formation processes of lamellar grain boundaries in titanium rich binary TiAl intermetallics were studied. TiAl alloys containing aluminum content of 44 to 48 at.% were induction-heated to 1723 K followed by helium-gas-quenching at various temperatures. For the Ti-44%Al, few lamellae were observed in samples quenched from higher than 1473 K. Although small peaks of beta phase were detected using X-ray diffraction, only the ordered hexagonal phase (${\alpha}_2$) with clear APB contrast was observed in TEM observation. For the Ti-48 at.%Al alloy, almost no lamellar structure, and straight grain boundaries were observed in samples quenched from higher than 1623 K. The formation of lamellae along grain boundaries was observed in the sample quenched from 1573 K. The fully lamellar microstructures with serrated boundaries were observed in samples quenched from lower than 1473 K. It was found that the formation of ${\gamma}$ platelets took place at higher temperatures in Ti-48 at.%Al than in Ti-44 at.%Al. Although the size of the serration is different, serrated lamellar grain boundaries could be obtained for all alloy compositions employed. The serration appeared to be due to the grain boundary migration induced by precipitation and growth of ${\gamma}$. Differences in transformation characteristics with aluminum content are discussed.

• Journal of Physiology & Pathology in Korean Medicine
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• v.24 no.4
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• pp.592-597
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• 2010

Cinnamomi Ramulus is one of the medicinal plants that have been used to improve various diseases caused by insufficient blood circulation. This study was performed for the investigation of vasodilation efficacy ethanol extract of Cinnamomi Ramulus (CR). CR exhibited vascular relaxation against phenylephrine (PE, $10^{-6}M$)-, KCl- and NaF-induced contraction in rat thoracic aorta. In addition, its relaxation was endothelium-independent. Treatment of potassium channel blockers such as gilbenclamide (Gli, $10^{-5}M$), tetraethylammonium (TEA, 1 mM) and 4-aminopyridine (4-AP, 0.2 mM) did not effect on the relaxation of CR. The relaxant effects were also not inhibited by pre-treatment of rat aorta with L-NAME ($10^{-4}M$), methylene blue ($10^{-5}M$), indomethacin ($10^{-5}M$), and atropine ($10^{-6}M$). However, nifedipine ($10^{-5}M$), L-type $Ca^{2+}$ channel blocker, in part attenuated the relaxation of CR ($0.2\;mg/m{\ell}$), but SK&F96365 ($3{\times}10^{-5}M$), receptor activated $Ca^{2+}$ channel blocker and 2-APB ($10^{-4}M$), store operated $Ca^{2+}$ channel blocker did not affact dilation of CR. These findings suggest that the endothelium-independent relaxation effect of CR is partly related with inhibition of $Ca^{2+}$ influx via voltage dependent $Ca^{2+}$ channel.

• International Journal of Oral Biology
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• v.40 no.1
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• pp.11-17
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• 2015

The gingival epithelium of the oral cavity is constantly exposed to exogenous stimuli such as bacterial toxins, allergens, and thermal changes. These exogenous stimuli are resisted by innate host defense in gingival epithelial cells. However, it is unclear exactly how the exogenous stimuli affect detrimentally on the human gingival epithelial cells. Here, we investigated whether the allergen, such as house dust mite (HDM) extract, is linked to $Ca^{2+}$ signaling and proinflammatory cytokine expression in primary cultured human gingival epithelial cells. HDM extract induced an increase in intracellular $Ca^{2+}$ concentration ($[Ca^{2+}]_i$) in a dose-dependent manner. Extracellular $Ca^{2+}$ depletion did not affected on the HDM extract-induced increase in $[Ca^{2+}]_i$. The HDM extract-induced increase in $[Ca^{2+}]_i$ was abolished by the treatment with U73122 and 2-APB, which are inhibitors of phospholipase C (PLC) and inositol 1,4,5-trisphosphate ($IP_3$) receptor. Moreover, HDM extract induced the mRNA expression of pro-inflammatory cytokine, interleukin (IL)-8. These results suggest that HDM extract triggers $PLC/IP_3$-dependent $Ca^{2+}$ signaling and IL-8 mRNA expression in primary cultured human gingival epithelial cells.

• The Korean Journal of Physiology and Pharmacology
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• v.16 no.1
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• pp.31-36
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• 2012

The receptor activator of NF-${\kappa}B$ ligand (RANKL) signal is an activator of tumor necrosis factor receptor-associated factor 6 (TRAF6), which leads to the activation of NF-${\kappa}B$ and other signal transduction pathways essential for osteoclastogenesis, such as $Ca^{2+}$ signaling. However, the intracellular levels of inositol 1,4,5-trisphosphate ($IP_3$) and $IP_3$-mediated cellular function of RANKL during osteoclastogenesis are not known. In the present study, we determined the levels of $IP_3$ and evaluated $IP_3$-mediated osteoclast differentiation and osteoclast activity by RANKL treatment of mouse leukemic macrophage cells (RAW 264.7) and mouse bone marrow-derived monocyte/macrophage precursor cells (BMMs). During osteoclastogenesis, the expression levels of $Ca^{2+}$ signaling proteins such as $IP_3$ receptors ($IP_3Rs$), plasma membrane $Ca^{2+}$ ATPase, and sarco/endoplasmic reticulum $Ca^{2+}$ ATPase type2 did not change by RANKL treatment for up to 6 days in both cell types. At 24 h after RANKL treatment, a higher steady-state level of $IP_3$ was observed in RAW264.7 cells transfected with green fluorescent protein (GFP)-tagged pleckstrin homology (PH) domains of phospholipase C (PLC) ${\delta}$, a probe specifically detecting intracellular $IP_3$ levels. In BMMs, the inhibition of PLC with U73122 [a specific inhibitor of phospholipase C (PLC)[ and of $IP_3Rs$ with 2-aminoethoxydiphenyl borate (2APB; a non-specific inhibitor of $IP_3Rs$) inhibited the generation of RANKL-induced multinucleated cells and decreased the bone-resorption rate in dentin slice, respectively. These results suggest that intracellular $IP_3$ levels and the $IP_3$-mediated signaling pathway play an important role in RANKL-induced osteoclastogenesis.

• Herbal Formula Science
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• v.27 no.4
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• pp.237-244
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• 2019

Objectives : The purpose of this study was to investigate the effects of Carthami flos on pacemaker potentials of small intestinal and colonic Interstitial Cells of Cajal (ICC). Methods : To dissociate the ICC, we used enzymatic digestions from the small intestine and colon in mice. In the ICC, the electrophysiological whole-cell patch-clamp configuration was used to record pacemaker potentials in the cultured ICC. Results : 1. The ICC generated pacemaker potentials in the murine small intestine and colon. 2. Pretreatment with a Ca²⁺ free solution and thapsigargin, a Ca²⁺-ATPase inhibitor in the endoplasmic reticulum, stopped the pacemaker potentials. In the case of Ca²⁺-free solutions, Carthami flos did not induce membrane depolarizations in the murine small intestine and colon. However, when thapsigargin in a bath solution was applied, Carthami flos induced membrane depolarizations only in the murine colon. 3. Pretreatment with 2-APB (transient receptor potential melastatin (TRPM) channel inhibitor) abolished the pacemaker potentials and suppressed Carthami flos-induced effects in the murine small intestine and colon. 4. However, pretreatment with T16Ainh-AO1 (Ca²⁺ activated Cl- channel; anoctamin 1 (ANO1) inhibitor) did not affect the pacemaker potentials and induced Carthami flos-induced effects only in the murine small intestine. Conclusions : These results suggest that Carthami flos can modulate the pacemaker activity of ICC and the mechanisms underlying pacemaking in ICC might be different in the small intestine and the colon.

• Fire Science and Engineering
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• v.32 no.3
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• pp.19-26
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• 2018

Experiments on the combustion characteristics of untreated wood specimens and also treated ones with boric acid and ammonium pentaborate were carried out using a cone calorimeter according to ISO 5660-1 standard. As a result, comparing to untreated specimen, the fire performance index (FPI) of the specimens treated with boron compounds increased by 1.2 to 2.1 times and the fire growth index (FGI) increased by 1.6 to 8.4%. Also, total smoke release rate (TSR) was 9.0 to 28.3% lower than that of the untreated specimen. It is understood that the test specimens treated with the boron compound produces a carbonized layer with a flame retarding effect. The highest CO concentration, 0.01112%, for the untreated specimen was observed at 418 s, but the specimens treated with boron compound decreased 13.2 to 37.5% compared to untreated specimen. Therefore, wood treated with boron compounds is expected to have lower fire hazards and risks.

• International Journal of Oral Biology
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• v.34 no.4
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• pp.215-222
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• 2009

Medial vestibular nucleus (MVN) neurons are involved in the reflex control of the head and eyes, and in the recovery of vestibular function after the formation of peripheral vestibular lesions. In our present study, whole cell patch clamp recordings were carried out on MVN neurons in brainstem slices from neonatal rats to investigate the actions of a group I metabotropic glutamate receptor (mGluR) agonist upon synaptic transmission and ionic currents. Application of the mGluR I agonist (S)-3,5- dihydroxyphenylglycine (DHPG) increased the frequency of miniature inhibitory postsynaptic currents (mIPSCs) but had no effect upon amplitude distributions. To then identify which of mGluR subtypes is responsible for the actions of DHPG in the MVN, we employed two novel subtype selective antagonists. (S)-(+)-$\alpha$-amino-a-methylbenzeneacetic acid (LY367385) is a potent competitive antagonist that is selective for mGluR1, whereas 2-methyl-6-(phenylethynyl)-pyridine (MPEP) is a potent noncompetitive antagonist of mGluR5. Both LY367385 and MPEP antagonized the DHPG-induced increase of mIPSCs, with the former being more potent. DHPG was also found to induce an inward current, which can be enhanced under depolarized conditions. This DHPG-induced current was reduced by both LY367385 and MPEP. The DHPG-induced inward current was also suppressed by the PLC blocker U-73122, the $IP_3$ receptor antagonist 2-APB, and following the depletion of the intracellular $Ca^{2+}$ pool by thapsigargin. These data suggest that the DHPG-induced inward current may be mainly regulated by the intracellular $Ca^{2+}$ store via the PLC-$IP_3$ pathway. In conclusion, mGluR I, via pre- and postsynaptic actions, may modulate the excitability of the MVN neurons.

• International Journal of Oral Biology
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• v.33 no.3
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• pp.117-123
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• 2008

Reactive oxygen species (ROS) are toxic agents that may be involved in various neurodegenerative diseases. Recent studies indicate that ROS can act as modulators of neuronal activity, and are critically involved in persistent pain primarily through spinal mechanisms. In the present study, whole cell patch clamp recordings were carried out to investigate the effects of tert-buthyl hydroperoxide (t-BuOOH), an ROS, on neuronal excitability and the mechanisms underlying changes of membrane excitability. In current clamp condition, application of t-BuOOH caused a reversible membrane depolarization and firing activity in substantia gelatinosa (SG) neurons. When slices were pretreated with phenyl-N-tert-buthylnitrone (PBN) and ascorbate, ROS scavengers, t-BuOOH failed to induce membrane depolarization. However, isoascorbate did not prevent t-BuOOH-induced depolarization, suggesting that the site of ROS action is intracellular. The t-BuOOH-induced depolarization was not blocked by pretreatment with dithiothreitol (DTT), a sulfhydryl-reducing agent. The membrane-impermeant thiol oxidant 5,5-dithiobis 2-nitrobenzoic acid (DTNB) failed to induce membrane depolarization, suggesting that the changes of neuronal excitability by t-BuOOH are not caused by the modification of extrathiol group. The t-BuOOH-induced depolarization was suppressed by the phospholipase C (PLC) blocker U-73122 and inositol triphosphate ($IP_3$) receptor antagonist 2-aminoethoxydiphenylbolate (APB), and after depletion of intracellular $Ca^{2+}$ pool by thapsigargin. These data suggest that ROS generated by peripheral nerve injury can induce central sensitization in spinal cord, and t-BuOOH-induced depolarization may be regulated by intracellular $Ca^{2+}$ store mainly via $PLC-IP_3$ pathway.