• The Korean Journal of Physiology and Pharmacology
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• v.16 no.1
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• pp.25-30
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• 2012

Under some pathological conditions as bile flow obstruction or liver diseases with the enterohepatic circulation being disrupted, regurgitation of bile acids into the systemic circulation occurs and the plasma level of bile acids increases. Bile acids in circulation may affect the nervous system. We examined this possibility by studying the effects of bile acids on gating of neuronal (N)-type $Ca^{2+}$ channel that is essential for neurotransmitter release at synapses of the peripheral and central nervous system. N-type $Ca^{2+}$ channel currents were recorded from bullfrog sympathetic neuron under a cell-attached mode using 100 mM $Ba^{2+}$ as a charge carrier. Cholic acid (CA, $10^{-6}M$) that is relatively hydrophilic thus less cytotoxic was included in the pipette solution. CA suppressed the open probability of N-type $Ca^{2+}$ channel, which appeared to be due to an increase in (no activity) sweeps. For example, the proportion of sweep in the presence of CA was ~40% at +40 mV as compared with ~8% in the control recorded without CA. Other single channel properties including slope conductance, single channel current amplitude, open and shut times were not significantly affected by CA being present. The results suggest that CA could modulate N-type $Ca^{2+}$ channel gating at a concentration as low as $10^{-6}M$. Bile acids have been shown to activate nonselective cation conductance and depolarize the cell membrane. Under pathological conditions with increased circulating bile acids, CA suppression of N-type $Ca^{2+}$ channel function may be beneficial against overexcitation of the synapses.

• The Korean Journal of Physiology and Pharmacology
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• v.24 no.3
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• pp.277-286
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• 2020

Polycystic kidney disease 2-like-1 (PKD2L1), also known as polycystin-L or TRPP3, is a non-selective cation channel that regulates intracellular calcium concentration. Calmodulin (CaM) is a calcium binding protein, consisting of N-lobe and C-lobe with two calcium binding EF-hands in each lobe. In previous study, we confirmed that CaM is associated with desensitization of PKD2L1 and that CaM N-lobe and PKD2L1 EF-hand specifically are involved. However, the CaM-binding domain (CaMBD) and its inhibitory mechanism of PKD2L1 have not been identified. In order to identify CaM-binding anchor residue of PKD2L1, single mutants of putative CaMBD and EF-hand deletion mutants were generated. The current changes of the mutants were recorded with whole-cell patch clamp. The calmidazolium (CMZ), a calmodulin inhibitor, was used under different concentrations of intracellular. Among the mutants that showed similar or higher basal currents with that of the PKD2L1 wild type, L593A showed little change in current induced by CMZ. Co-expression of L593A with CaM attenuated the inhibitory effect of PKD2L1 by CaM. In the previous study it was inferred that CaM C-lobe inhibits channels by binding to PKD2L1 at 16 nM calcium concentration and CaM N-lobe at 100 nM. Based on the results at 16 nM calcium concentration condition, this study suggests that CaM C-lobe binds to Leu-593, which can be a CaM C-lobe anchor residue, to regulate channel activity. Taken together, our results provide a model for the regulation of PKD2L1 channel activity by CaM.

• Asian Journal of Turfgrass Science
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• v.9 no.4
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• pp.343-350
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• 1995

Samples from the L, F, H and $A_1$ horizons of the Phragmites longivalvis grassland were collected in a delta of the Nakdong River and the removal rates of N, P, K, Ca and Na were investigated. The results obtained in this study can be abstracted as follows; The removal fractions of N, P, K, Ca and Na of the litter were 0.56, 1.22, 1.95, 0.65 and 0.53, respectively. The half times of N, P, K, Ca and Na required for the remove or accumulation of the litter on the grassland floor were 1.23, 0.57, 0.36, 1.06 and 1.32 years, respectively. The increasing order of the turnover parameters of the elements was Na, N, Ca, P and K.

• The Korean Journal of Pharmacology
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• v.32 no.1
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• pp.39-49
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• 1996

In the present study, we observed change in intracellular $Ca^{2+}$$([Ca^{2+}]_i)$ as measured with the fluorescent $Ca^{2+}-indicator$ fura-2 in association with force development of the rat basilar arteries during activation by$K^+$ depolarizing solution and U46619, a thromboxane analogue, in the absence and the presence of calcitonin-gent related peptide (CGRP). CGRP (30 and 100 nM) caused a concentration-dependent inhibition of U46619-induced contraction with decrease in $[Ca^{2+}]_i$, whereas it did not exert any effect on the $K^+$ (90 mM)-induced contraction and increase in $[Ca^{2+}]_i$, Further, $[Ca^{2+}]_i-force$ relationships were determined by plotting the ratio of $F_{340}/F_{380}$ $([Ca^{2+}]_i)$ as a function of the force induced by U46619, and the results were compared with those obtained in the presence of CGRP. The curves obtained in the presence of CGRP (30 and 100 nM) were significantly moved to downward without right shift of the curves suggesting that CGRP inhibited the U46619-induced contraction only by mediation of reduction in $[Ca^{2+}]_i$ with out any change in the sensitivity of contractile apparatus to $Ca^{2+}$. The CGRP-induced attenuation of $[Ca^{2+}]_i$ and force development was significantly inhibited under pretreatment with CGRP $(8{\sim}37)$ fragment (100 nM), a CGRP1 receptor antagonist. Both the reduced contraction and reduction in $[Ca^{2+}]_i$ caused by CGRP were fully reversed by pretreatment with charybdotoxin (100 nM) and iberiotoxin (100 nM), large conductance $Ca^{2+}-activated$ $K^+$ channel blockers, but not by apamin (300 nM), a small conductance $Ca^{2+}-activated$ $K^+$ channel blocker, and glibenclamide ( 1 ${\mu}M$), an ATP-sensitive $K^+$ channel blocker. In conclusion, it is suggested that the CGRP1 receptor, upon activation by CGRP, are coupled to opening of $Ca^{2+}-activated$ $K^+$ channel and cause to decrease in $[Ca^{2+}]_i$, thereby leading to vasodilation of the rat basilar artery. However, it is not defined that the mechanism underlying vasodilation whether the $K^+$ channel blockers, charybdotoxin and iberiotoxin directly block the CGRP receptors and that CGRP-evoked relaxation is dependent on the cyclic AMP or $K^+$ channel opening or both actions.

• Journal of the Korean Ceramic Society
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• v.27 no.6
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• pp.799-807
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• 1990

In this study, effects of oxide additives on mechanical properties and microstructure of A1N and A1N polytype ceramics were investigated. Fine A1N powder was synthesized by nitriding alumiuim hydroxide prepared from Al-isopropoxide, at 1350$^{\circ}C$ for 10h in N2 atmosphere. By adding 3w/o Y2O3, 0.56w/o CaO, and 10w/o SiO2 to AlN powder, AlN and AlN polytype ceramics were prepared by hot-pressing under the pressure of 30 MPa at 1800$^{\circ}C$ for 1h. AlN ceramics with no additives formed considerable amount of AlON phase, while AlN ceramics doped with Y2O3 or CaO decreased AlON phase and formed Y-Al or Ca-Al oxide compound. AlN＋10w/o SiO2(＋3w/o Y2O3) composition produced AlON and AlN polytype compound having 21R as a major phase. Room temperature flexural strength of AlN ceramics with no additive was 246MPa, and room temperature flexural strength and critical temperature difference by thermal shock(ΔTc) of AlN ceramics dooped with Y2O3 or CaO were 532MPa/340$^{\circ}C$ and 423MPa/300$^{\circ}C$, respectively. Y2O3 and CaO used as sintering agent played roles of densification and oxygen removal of AlN ceramics, and affected grain growth/grain morphologies of AlN ceramics.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.6
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• pp.1115-1121
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• 2007

[ $Bi_2Sr_2Ca{_{n-1}}Cu_nO_x$ ](n=0,1,2) thin fans have been fabricated by co-deposition at an ultra-low growth rate using ion beam sputtering(IBS) method. Bi 2212 phase appeared in the temperature range of 750 and $795^{\circ}C$ and single phase of Bi 2201 existed in the lower region than $785^{\circ}C$. Whereas, $PO_3$ dependance on structural formation was scarcely observed regardless of the pressure variation. And high quality of c-axis oriented Bi 2212 thin film with $T_c$(onset) of about 90 K and $T_c$(zero) of about 45 K is obtained. Only a small amount of CuO in some films was observed as impurity, and no impurity phase such as $CaCuO_2$ was observed in all of the obtained films.

• Journal of environmental and Sanitary engineering
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• v.5 no.1
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• pp.28-33
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• 1990

The turnover rates of nitrogen(N), phosphorus(P), calcium(Ca), potassium(K), and sodium(Na) during the decomposition of litter were studied in the Pinus koraiensis forest in Choon Chun and in the Pinus rigida forest in Mt. Gwanak, Seoul. The turnover rates of N, P, K, Ca, and Na were 0.064, 0.068, 0.040, 0.417, and 0.058 for the P. korai ensis litter and 0.049, 0.049, 0.023, 0.346, and 0.058 for the P. rigida litter respectively. The loss of elements follows the order Ca>P>N>Na>K in the P. koraiensis litter and the order Ca>Na>N=P>K in the P. rigida litter. Generally the turnover rates of cations were greater than those of anions.

• BMB Reports
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• v.28 no.5
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• pp.392-397
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• 1995

The effect of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) on the intracellular $Ca^{2+}$ level was studied in NIH3T3 fibroblast cells. A reduction of the intracellular $Ca^{2+}$ level was observed after exposure to 300 ${\mu}m$ MNNG. However, the intracellular level of $IP_3$, a well-known regulator of $Ca^{2+}$ release from internal storage, was not changed by MNNG treatment. Instead, a reduction of the intracellular NAD level was observed. NAD as well as $IP_3$ stimulated intracellular $Ca^{2+}$ release from permeabilized cells. The treatment of 3-aminobenzamide, which inhibited the MNNG-induced reduction of the NAD level, also prevented the MNNG-induced decrease of the $Ca^{2+}$ level. Our data suggest that MNNG reduces the intracellular $Ca^{2+}$ level by NAD depletion in NIH3T3 cells.

• Journal of Chest Surgery
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• v.53 no.5
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• pp.270-276
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• 2020

Background: We investigated the impact of previous catheter ablation (CA) on the midterm outcomes of totally thoracoscopic ablation in patients with lone atrial fibrillation (AF). Methods: Between February 2012 and July 2018, 332 patients underwent totally thoracoscopic ablation for the treatment of AF (persistent AF; n=264, 80%). The patients were stratified into CA (n=47, 14%) and non-CA (nCA; n=285, 86%) groups according to their CA history. Results: All the baseline clinical characteristics and risk factors were similar between the groups except for age, percentage of male patients, prevalence of paroxysmal AF, prior percutaneous coronary intervention, and left atrial volume index (LAVI). No significant intergroup differences were observed in the incidence of early and late complications. At late follow-up, normal sinus rhythm was observed in 92% (43 of 47) of the patients in the CA group and 85% (242 of 285) of the patients in the nCA group (p=0.268). The rate of freedom from AF recurrence at 5 years was 55.3%±11.0% in the CA group, which was similar to that in the nCA group (55.7%±5.1%, p=0.690). In Cox regression analysis, preoperative brain natriuretic peptide levels and LAVI were associated with AF recurrence, but CA history was not significant. Conclusion: Totally thoracoscopic ablation was safe and effective in treating AF irrespective of CA history. A history of CA did not appear to affect the procedural complexity.

• Journal of the Korean Chemical Society
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• v.37 no.1
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• pp.36-42
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• 1993

In the presence of $Ca^{2+}$ ion, the charge transfer (CT) interaction of nonionic surfactants, $nonylphenol-(ethylene oxide)_n\;[NP-(EO)_n; n = 11, 40, 100]$ with iodine in aqueous solution were investigated by UV-visible spectrophotometer. The characteristics of spectra depended on the concentration of $Ca^{2+}$ ion and the number of EO unit. Above CMC, the intensity of the CT band by the addition of $Ca^{2+}$ ion for the $NP-(EO)_{11}$ and $NP-(EO)_{40}$ increased and then decreased, while for the $NP-(EO)_{100}$ continuously increased. The increase in the intensity of CT band were attributed to the compactness of micelle in the presence of $Ca^{2+}$ ion. These phenomena may be explained by the fact that the linear ethylene oxide (EO) chain, to be free configuration in aqueous solution, could form a pseudo-crown ether structures capable of forming complexes with $Ca^{2+}$ ion.