• Progress in Superconductivity
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• v.1 no.1
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• pp.1-8
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• 1999

The magnetization and/or resistivity of high $T_c$ superconductors ($YBa_2Cu_3O_{7-\delta}$(YBCO) single crystal, $Bi_2Sr_2CaCu_2O_8$ (Bi-2212) single crystal, $Tl_2Ba_2CaCu_2O_8$ (Tl-2212) film, $HgBa_2Ca_2Cu_3O_8$ (Hg-1223) film) have been measured as a function of magnetic field H and temperature T. The extracted fluctuation part of the magnetization and conductivity exhibits a critical behavior consistent with the three-dimensional XY model. The dynamic critical exponent z does not sensitively vary with a type of the superconductors. The value of z ranges from 1.5 to $1.8{\pm}0.1$. However, the static critical exponent ${\nu}$ is the most largely increased in Tl-2212 that has a weaker interlayer coupling strength than YBCO; the value of ${\nu}$ is 0.669, 0.909, 1.19, and 1.338 for YBCO, Bi-2212, Hg-1223, and Tl-2212 respectively. The results indicate that the weak interlayer coupling along the c-axis of high $T_c$ superconductors near $T_c$ does not influence the dynamic critical exponent z (the same value of superfluid $^4He$), but significantly increases the static critical exponent ${\nu}$.

• Journal of Microbiology and Biotechnology
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• v.15 no.3
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• pp.665-671
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• 2005

Initiation and activation of sperm motility are prerequisite processes for the contact and fusion of male and female gametes at fertilization. The phenomena are under the regulation of cAMP and $Ca^{2+}$ in vertebrates and invertebrates. Mammalian sperm requires $Ca^{2+}$ and cAMP for the activation of sperm motility. Cell signaling for the initiation and activation of sperm motility in the ascidians and salmonid fishes has drawn much attention. In the ascidians, the sperm-activating and attracting factors from unfertilized egg require extracellular $Ca^{2+}$ for activating sperm motility and eliciting chemotactic behavior toward the egg. On the other hand, the cAMP-dependent phosphorylation of protein is essential for the initiation of sperm motility in salmonid fishes. A decrease of the environmental $K^+$ concentration surrounding the spawned sperm causes $K^+$ efflux and $Ca^{2+}$ influx through the specific $K^+$ channel and dihydropyridine-sensitive L-/T-type $Ca^{2+}$ channel, respectively, thereby leading to the membrane hyperpolarization. The membrane hyperpolarization induces synthesis of cAMP, which triggers further cell signaling processes, such as cAMP-dependent protein phosphorylation, to initiate sperm motility in salmonid fishes. This article reviews the studies on the physiological mechanisms of sperm motility and its cell signaling in aquatic species.

• The Korean Journal of Physiology and Pharmacology
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• v.24 no.6
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• pp.529-543
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• 2020

In contrast to ventricular myocytes, the structural and functional importance of atrial transverse tubules (T-tubules) is not fully understood. Therefore, we investigated the ultrastructure of T-tubules of living rat atrial myocytes in comparison with ventricular myocytes. Nanoscale cell surface imaging by scanning ion conductance microscopy (SICM) was accompanied by confocal imaging of intracellular T-tubule network, and the effect of removal of T-tubules on atrial excitation-contraction coupling (EC-coupling) was observed. By SICM imaging, we classified atrial cell surface into 4 subtypes. About 38% of atrial myocytes had smooth cell surface with no clear T-tubule openings and intracellular T-tubules (smooth-type). In 33% of cells, we found a novel membrane nanostructure running in the direction of cell length and named it 'longitudinal fissures' (LFs-type). Interestingly, T-tubule openings were often found inside the LFs. About 17% of atrial cells resembled ventricular myocytes, but they had smaller T-tubule openings and a lower Z-groove ratio than the ventricle (ventricular-type). The remaining 12% of cells showed a mixed structure of each subtype (mixed-type). The LFs-, ventricular-, and mixed-type had an appreciable amount of reticular form of intracellular T-tubules. Formamide-induced detubulation effectively removed atrial T-tubules, which was confirmed by both confocal images and decreased cell capacitance. However, the LFs remained intact after detubulation. Detubulation reduced action potential duration and L-type Ca²⁺ channel (LTCC) density, and prolonged relaxation time of the myocytes. Taken together, we observed heterogeneity of rat atrial T-tubules and membranous ultrastructure, and the alteration of atrial EC-coupling by disruption of T-tubules.

• Journal of Life Science
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• v.28 no.8
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• pp.892-899
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• 2018

Portulaca oleracea L. is an edible plant widely consumed in daily diet throughout Europe, Asia and America. In this study, protective effects of P. oleracea L. extracts against oxidative stress and matrix metalloproteinase (MMP) activity induced by ultraviolet B (UVB) radiation were investigated using HaCaT immortal human keratinocytes. In this context, the mRNA and protein productions of MMPs (MMP-1, -2, and -9) and type I procollagen, which are major markers of photoaging induced by UVB radiation in HaCaT keratinocytes, were evaluated. Furthermore, UVB-induced reactive oxygen species (ROS) generation and mRNA and protein expression levels of superoxide dismutase-1 (SOD-1), oxygenase-1 (OH-1), and nuclear factor-erythroid 2-related factor-2 (Nrf-2), all of which are associated with the antioxidant balance, were investigated. As shown by the results, UVB radiation induced ROS formation and led to increased production of MMPs and decreased collagen production in human keratinocytes, which resulted in skin photoaging or photodamage. The treatment with P. oleracea L. extracts downregulated MMP (MMP-1, -2, and -9) production and upregulated type I procollagen expression in UVB-induced HaCaT cells. Furthermore, treatment with the extracts decreased UVB-induced ROS generation and increased the expression of antioxidant enzymes, such as SOD-1 and OH-1, through the Nrf-2 pathway. Taken together, these results suggest that P. oleracea L. extracts could be a potential cosmeceutical agent for the prevention of skin photoaging or photodamage.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.139.1-139.1
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• 2012

Wilson and Bappu (1957) found a significant relationship (WBR) between the absolute magnitude ($M_v$) and the width of the Ca II K emission line (W) for late type stars. In this study, we revisit the WBR to claim that WBR can be an excellent indicator of stellar surface gravity. We analyze 95 high-resolution spectra of G, K and M type stars obtained with UVES and BOES. WBR found in this work is $M_v$=34.22-18.34logW. In addition, stellar atmospheric parameters ($T_{eff}$, logg, [Fe/H], ${\xi}_{tur}$) are determined with the MOOG code and the Kurucz ATLAS9 model grids for G and K type stars. For M type stars, the method of Belle et al. (1999) is used to derive effective temperature which shows good agreement with other methods. Using the derived $T_{eff}$ and the measured logW,we find the relationship between logg and [logW, logT]; ${\log}g-_{fit}=-25.051-5.527{\log}W+10.254{\log}T_{eff}$. This relation can be applied to estimate the surface gravity of M type stars, which is difficult to be determined by other methods.

• Journal of Physiology & Pathology in Korean Medicine
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• v.21 no.4
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• pp.1017-1024
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• 2007

Thymus and activation-regulated chemokine (TARC/CCL-17), produced by keratinocytes, is a CC chemokine known to selectively Th2 type T cells via $CCR4^+$ and is implicated in the development of atopic dermatitis (AD). TARC/CCL17 expression was induced by cytokines such as tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$) and interferon-${\gamma}$ (IFN-${\gamma}$). We recently found that the wogonin, a flavone isolated from Scutellaria baicalensis, suppressed TARC expression via heme oxygenase 1 (HO1) in human keratinocytes induced with mite antigen. However, little is known about the inhibitory mechanism of wogonin on TARC/CCL-17 expression stimulated with cytokines. To investigate the inhibitory mechanism, I determined the inhibitory effects of wogonin on the activation of nuclear factor-${\kappa}B$ (NF-${\kappa}B$) and $I{\kappa}B{\alpha}$ phosphorylation, and also examined the activation of p38 MAP kainase in HaCaT keratinocytes stimulated with TNF-${\alpha}$ and IFN-${\gamma}$. Wogonin inhibited NF-${\kappa}B$-DNA complex, NF-${\kappa}B$ binding activity, and the phosphorylation of $I{\kappa}B{\alpha}$ in a dose dependent manner. Wogonin also inhibited the translocation of NF-${\kappa}B$ from cytosol to nucleus. Moreover, the phosphorylation of of p38 MAP kinase in the TNF-${\alpha}$ and IFN-${\gamma}$-stimulated HaCaT keratinocytes were suppressed by wogonin in a dose dependent manner. These results suggest that wogonin may inhibit cytokine-induced NF-${\kappa}B$ activation by $I{\kappa}B{\alpha}$ degradation via suppression of p38 MAP kinase signaling pathway in keratinocytes and modulation of wogonin signaling pathway may be beneficial for the treatment of AD.

• The Journal of Korean Medicine
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• v.44 no.2
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• pp.119-131
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• 2023

Objectives: Betula Platyphylla(BP) has been used as a analgesic, anti-microbial, anti-oxidant drug in Eastern Asia. However, it is still unknown whether BP ethanol extract could exhibit the inhibitory activities against ultraviolet B(UVB)-induced skin injury on human keratinocytes, HaCaT cells. This study was aimed to investigate the protective activity of BP ethanol extract on UVB-irradiated skin injury in HaCaT cells. Methods: The skin injury model of HaCaT cells was established under UVB stimulation. HaCaT keratinocyte cells were pre-treated with BP ethanol extract for 1 h, and then stimulated with UVB. Then, the cells were harvested to measure the cell viability, production of reactive oxygen species(ROS), pro-inflammatory cytokines such as interleukin(IL) 1-beta, IL-6, and tumor necrosis factor(TNF)-𝛼, hyaluronidase, type 1 collagen, matrix metalloproteinase(MMP)s. In addition, we examined the mitogen activated protein kinases(MAPKs) and inhibitory kappa B alpha(I𝜅;-B𝛼) as inhibitory mechanisms of BP ethanol extract. Results: The treatment of BP ethanol extract inhibited the UVBinduced cell death and ROS production in HaCaT cells. BP ethanol extract treatment inhibited the UVB-induced increase of IL-1beta, IL-6, and TNF-𝛼. BP ethanol extract treatment inhibited the increase of hyaluronidase, MMP and decrease of collagen. BP ethanol extract treatment inhibited the activation of MAPKs and the degradation of I𝜅-B𝛼. Conclusions: Our result suggest that treatment of BP ethanol extract could inhibit the UVB-induced skin injury via deactivation of MAPKs and nuclear factor kappa B(NF-𝜅B) in HaCaT cells. This study could suggest that BP ethanol extract could be a beneficial agent to prevent skin damage or inflammation.

• Journal of Magnetics
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• v.16 no.4
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• pp.457-460
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• 2011

In this paper, magnetic property and magnetocaloric effect (MCE) in perovskite manganites of the type $La_{(0.75-X)}Ce_XCa_{0.25}MnO_3$ (x = 0.0, 0.2, 0.3 and 0.5) synthesized by using the standard solid state reaction method have been reported. From the magnetic measurements as a function of temperature and applied magnetic field, we have observed that the Curie temperature ($T_C$) of the prepared samples strongly dependent on Ce content and was found to be 255, 213 and 150 K for x = 0.0, 0.2 and 0.3, respectively. A large magnetocaloric effect in vicinity of $T_C$ has been observed with a maximum magnetic entropy change (${\mid}{\Delta}S_M{\mid}_{max}$) of 3.31 and 6.40 J/kgK at 1.5 and 4 T, respectively, for $La_{0.55}Ce_{0.2}Ca_{0.25}MnO_3$. In addition, relative cooling power (RCP) of the sample under the magnetic field variation of 1.5 T reaches 59 J/kg. These results suggest that $La_{0.55}Ce_{0.2}Ca_{0.25}MnO_3$ compound could be a suitable candidate as working substance in magnetic refrigeration at 213 K.

• Biomolecules & Therapeutics
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• v.16 no.4
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• pp.394-402
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• 2008

Atopic dermatitis (AD) is an inflammatory skin disease commonly characterized by infiltration of inflammatory cells into skin lesions. Keratinocytes produce many chemokines that are involved in the pathogenesis of skin disorders. In particular, macrophage-derived chemokine (MDC/CCL22) and thymus and activationregulated chemokine (TARC/CCL17) are Th2-type cytokines. Serum MDC and TARC levels are increased in AD patients. In this study, we investigated the anti-inflammatory effect and mechanism of action of the active fraction from Prunus yedoensis bark. We evaluated their inhibitory effects on the AD-like inflammatory markers (MDC and TARC) and JAK-STAT pathway (STAT1) in HaCaT keratinocytes. The EtOAc fraction of the crude extract (80% EtOH) and the E5 sub-fraction potently inhibited the induction of MDC and TARC mRNA and protein at 50 ${\mu}g$/mL in HaCaT cells. In addition, the E5 sub-fraction inhibited the phosphorylation of STAT1 protein associated with IFN-$\gamma$ signaling transduction in a dose-dependent manner. Thus, P. yedoensis may have antiatopic activity by suppressing the inflammatory chemokines (MDC and TARC).

• Food Science and Preservation
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• v.5 no.2
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• pp.105-110
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• 1998

To find out suitable storage and marketing condition, northern type 'seosan' garlic was stored for 3 months at controlled atmosphere(CA), modified atmosphere(MA), low(0~1$^{\circ}C$) and room temperature(20$\pm$5$^{\circ}C$), and then marketed at low(2~3$^{\circ}C$) and room temperature (20$\pm$5$^{\circ}C$)after storage. The physiological properties of garlic were investigated among treatments. The garlic respiration increased after 2 months at room temperature storage, which seem to be dormancy break time. During storage of garlic by CA, MA condition, sprouting and weight loss were prevented effectively by suppress of respiration, and hardness was maintained higher then those of the others. Decay rate occurred 8.1% at room temperature storage, 2% at MA storage but didn't occurred at CA and low temperature storages. When marketed at room and low temperature after storage, increment of respiration and sprouting were delayed, and changes of weight and hardness were low in garlics stored at CA and MA. Decay rate occurred high in garlics stored at MA and room temperature.