• Molecules and Cells
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• v.44 no.10
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• pp.758-769
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• 2021

Calcium homeostasis modulator 1 (CALHM1) is a membrane protein with four transmembrane helices that form an octameric ion channel with voltage-dependent activation. There are four conserved cysteine (Cys) residues in the extracellular domain that form two intramolecular disulfide bonds. We investigated the roles of C42-C127 and C44-C161 in human CALHM1 channel biogenesis and the ionic current (I_CALHM1). Replacing Cys with Ser or Ala abolished the membrane trafficking as well as I_CALHM1. Immunoblotting analysis revealed dithiothreitol-sensitive multimeric CALHM1, which was markedly reduced in C44S and C161S, but preserved in C42S and C127S. The mixed expression of C42S and wild-type did not show a dominant-negative effect. While the heteromeric assembly of CALHM1 and CALHM3 formed active ion channels, the co-expression of C42S and CALHM3 did not produce functional channels. Despite the critical structural role of the extracellular cysteine residues, a treatment with the membrane-impermeable reducing agent tris(2-carboxyethyl) phosphine (TCEP, 2 mM) did not affect I_CALHM1 for up to 30 min. Interestingly, incubation with TCEP (2 mM) for 2-6 h reduced both I_CALHM1 and the surface expression of CALHM1 in a time-dependent manner. We propose that the intramolecular disulfide bonds are essential for folding, oligomerization, trafficking and maintenance of CALHM1 in the plasma membrane, but dispensable for the voltage-dependent activation once expressed on the plasma membrane.

• Restorative Dentistry and Endodontics
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• v.30 no.5
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• pp.372-384
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• 2005

The purpose of this study was to monitor the secretion of matrix metalloproteinase (MMP) and tissue inhibitor of metalloproteinase (TIMP) by human periodontal ligament (PDL) fibroblasts stimulated with Prevotella nigrescens lipopolysaccharide (LPS), and to examine the effect of calcium hydroxide treatment on P. nigrescens LPS. LPS was extracted and purified from anaerobically cultured P. nigrescens. PDL fibroblasts were stimulated by the LPS (0, 0.1, 1, 10 ${\mu}g/ml$) or LPS (10 ${\mu}g/ml$) pretreated with 12.5 mg/ml of $Ca(OH)_2$ for 3 days, for various periods of time (12, 24, 48 h). Immunoprecipitation were performed for protein level analysis of MMP-1 MMP-2 and TIMP-1. Total RNA was isolated and real-time quantitative polymerase chain reaction (PCR) was performed for quantification of MMP-1 mRNA. According to this study, the results were as follows: 1. The p개duction of MMP-1 by stimulation with P. nigrescens LPS increased in time-dependent manner, and showed maximum value at 48 h in both protein and mRNA level. But there was no dose-dependent increas. 2. MMP-2 production time-dependently increased when stimulated with 1 and 10 ${\mu}g/ml$LPS, but there was no dose-dependent increase. 3. TIMP-1 p개duction increased to 24 h, but decreased at 48 h. It increased when stimulated with 0.1 and 1${\mu}g/ml$, but suppressed at 10 ${\mu}g/ml$ .4. P. nigrescens LPS pretreated with $Ca(OH)_2$ markedly downregulated MMP-1 gene expression.

• The Journal of the Acoustical Society of Korea
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• v.35 no.4
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• pp.295-302
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• 2016

Underwater acoustic communication channel is often defined as a multipath fading channel since the multipath arrivals from various paths interfere with each other and cause frequency dependent constructive or destructive interference in received signals. Therefore signal-to-noise ratio (SNR) of received signal fluctuates as a function of frequency. In addition, sea surface fluctuation induces frequency dependent time variant signal fading due to coherent component variation of surface bounce path. The frequency shift keying (FSK) system is known to be less sensitive and more robust under these interference and fading, and M-ary frequency shift keying (MFSK) system is adopted to increase a data rate. In this study, a bit error rate (BER) of 4 channels 4FSK system are examined in shallow sea multipath channel. Experimental results show that RS code reduces efficiently the BER of 4FSK system since frequency dependent time-varying fading is characterized to give burst errors. The BER of a different data rate or different source-to-receiver range depends on not only the channel coherent bandwidth but also frequency dependent multipath fading.

• Structural Engineering and Mechanics
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• v.77 no.2
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• pp.197-215
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• 2021

Under a severe environment of multiple hazards such as earthquakes and winds, the life-cycle performance of engineering structures may inevitably be deteriorated due to the fatigue effect caused by long-term exposure to wind loads, which would further increase the structural vulnerability to earthquakes. This paper presents a framework for evaluating the lifetime structural seismic performance under the effect of wind-induced fatigue considering different sources of uncertainties. The seismic behavior of a high-rise steel-concrete composite frame with buckling-restrained braces (FBRB) during its service life is systematically investigated using the proposed approach. Recorded field data for the wind hazard of Fuzhou, Fujian Province of China from Jan. 1, 1980 to Mar. 31, 2019 is collected, based on which the distribution of wind velocity is constructed by the Gumbel model after comparisons. The OpenSees platform is employed to establish the numerical model of the FBRB and conduct subsequent numerical computations. Allowed for the uncertainties caused by the wind generation and structural modeling, the final annual fatigue damage takes the average of 50 groups of simulations. The lifetime structural performance assessments, including static pushover analyses, nonlinear dynamic time history analyses and fragility analyses, are conducted on the time-dependent finite element (FE) models which are modified in lines with the material deterioration models. The results indicate that the structural performance tends to degrade over time under the effect of fatigue, while the influencing degree of fatigue varies with the duration time of fatigue process and seismic intensity. The impact of wind-induced fatigue on structural responses and fragilities are explicitly quantified and discussed in details.

• Journal of the Institute of Convergence Signal Processing
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• v.16 no.2
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• pp.40-43
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• 2015

In this paper, the effects of the leading and the following sounds with single frequency on sound localization are investigated. The sounds with different levels and ISIs(Inter Stimuli Intervals) were used. The width of test sound is 2ms, and those of the leading and the following sounds are 10ms. 1 kHz of the test sound is utilized. The arrival time difference in the subject's ears is set to be 0.5ms. The four kinds of level differences used for one ISI are 0, -10, -15, and -20dB interval. The leading sound is found to have more effect on sound localization than the following sound is. The effect of the leading sound is also found to be dependent on the value of ISI. When the value of the ISI is small, different effects affecting the sound localization are observed.

• The Korean Journal of Physiology and Pharmacology
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• v.7 no.1
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• pp.15-23
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• 2003

Cellular redox state is known to be perturbed during ischemia and that $Ca^{2+}$ and $K^2$ channels have been shown to have functional thiol groups. In this study, the properties of thiol redox modulation of the ATP-sensitive $K^2$ ($K_{ATP}$) channel were examined in rabbit ventricular myocytes. Rabbit ventricular myocytes were isolated using a Langendorff column for coronary perfusion and collagenase. Single-channel currents were measured in excised membrane patch configuration of patch-clamp technique. The thiol oxidizing agent 5,5'-dithio-bis-(2-nitro-benzoic acid) (DTNB) inhibited the channel activity, and the inhibitory effect of DTNB was reversed by dithiothreitol (disulfide reducing agent; DTT). DTT itself did not have any effect on the channel activity. However, in the patches excised from the metabolically compromised cells, DTT increased the channel activity. DTT had no effect on the inhibitory action by ATP, showing that thiol oxidation was not involved in the blocking mechanism of ATP. There were no statistical difference in the single channel conductance for the oxidized and reduced states of the channel. Analysis of the open and closed time distributions showed that DTNB had no effect on open and closed time distributions shorter than 4 ms. On the other hand, DTNB decreased the life time of bursts and increased the interburst interval. N-ethylmaleimide (NEM), a substance that reacts with thiol groups of cystein residues in proteins, induced irreversible closure of the channel. The thiol oxidizing agents (DTNB, NEM) inhibited of the $K_{ATP}$ channel only, when added to the cytoplasmic side. The results suggested that metabolism-induced changes in the thiol redox can also modulate $K_{ATP}$ channel activity and that a modulatory site of thiol redox may be located on the cytoplasmic side of the $K_{ATP}$ channel in rabbit ventricular myocytes.

• Journal of the Korean Geotechnical Society
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• v.15 no.2
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• pp.95-104
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• 1999

The bearing capacity of piles driven in soils showing set-up tendency increases with time. Though WEAP is an excellent tool for evaluating the driveability of driven pile, it has some limitations to predict reliable bearing capacity of pile after driving. It is because the existing WEAP method cannot take into account time-dependent soil properties after driving. The set-up effect should be accounted for to obtain a reliable bearing capacity by the WEAP. Unfortunately, there are no sufficient methods to take the set-up effect into consideration in wave equation analysis. This paper suggests an alternative to consider time effect in wave equation analysis through statistical analysis of dynamic load test data both at the end of driving and in the beginning of restrike. It is shown that the suggested parameters(quake and damping) would be more reliable than the existing one for the wave equation analysis of driven piles.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.10a
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• pp.196-203
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• 2000

In this study, the evaluation method of diffusion characteristics of Suspended Soli&SS) and the generation limit(source and thick) are investigated, which is significantly affecting on marine examined by construction works such as dredging and reclamation. Dispersion characteristics of SS is examined by hydraulic tests and numerical works in consideration with the Pusan Port. Hydraulic model test was performed in 2-D wave flume to find the limit wave conditon of re-suspension of solid as well as the time dependent characteristics of settlement The results obtainded in the study are as follows; 1) The quantituative evaluation af SS is the basic parameter of marine environmental impact assessment in related with the port development The SS increases as the water content of sea bed solid increases and the density decreases. 2) The sea bed solid in Sinsundai area, Pusan Port has the water content range of 83~157% 3) The ratio of suspension velocity against settlement velocity is about 0.25 and SS concentration converges as the wave heigh. 4) The SS increases 2 time when time step increases 3 time(10 sec to 30 sec) in numerical simulation It means that the effect of the time step should be checked in detail to stable. The diffusion The diffusion coefficient are Affiected senstively in the dispersion process while sea ved friction coefficinet have not strong relation in the simulated area

• Food Science and Biotechnology
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• v.14 no.6
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• pp.808-812
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• 2005

The effects of high pressure processing, pressure level (50, 100, 150, and 200 MPa) and pressurized time (0, 5, 10, 15, 30, 45, and 60 min) on the physico-chemical properties of pork M. longissimus dorsi were evaluated. The pH value was affected by both pressure level and pressurized time, especially at 200 MPa (P<0.05). In color measurement, $L^*$ and $a^*$-values were increased by both pressure level and pressurized time, but $b^*$-value did not differ significantly (P>0.05). Water holding capacity (WHC) was significantly decreased (P<0.05) depending on pressure level and pressurized time, while cooking loss was gradually increased. Warner-Bratzler shear force did not differ significantly (P>0.05) among the treatments. These results indicate that high pressure processing below 200 MPa for 1 hr had no effect on the quality of cooked meat, although some alterations were observed before cooking.

• Journal of Magnetics
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• v.21 no.1
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• pp.141-147
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• 2016

Staphylococcus aureus cultures exposed to rotating magnetic field (RMF) were studied in order to analyse the possible induced changes in staphylococcal enterotoxin genes (se) expression. Liquid cultures of S. aureus strains carrying different se were exposed to the RMF of magnetic frequency 50 Hz and magnetic induction 34 mT for 10 h at $37^{\circ}C$. Three time points of bacterial growth cycle were considered for RNA extractions. Gene expression analyses were evaluated using real-time quantitative PCR method. The present study confirmed, that the RMF can stimulate the growth rate of S. aureus cultures in comparison to the unexposed controls, while the stimulation is not strain dependent. The studies have also shown, that the RMF, depending on the exposure time but regardless the bacterial strain, can influence on the expression of various se. In general, except for sea, as a result of bacterial exposure to the RMF through subsequent growth phases, the expression of se decreased, reaching the values below results recorded for unexposed controls. In the case of sea expression remained at a lower level as compared to the control, regardless the time of exposition.