• The Korean Journal of Physiology and Pharmacology
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• v.18 no.4
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• pp.341-346
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• 2014

Lubiprostone is a chloride ($Cl^-$) channel activator derived from prostaglandin $E_1$ and used for managing constipation. In addition, lubiprostone affects the activity of gastrointestinal smooth muscles. Interstitial cells of Cajal (ICCs) are pacemaker cells that generate slow-wave activity in smooth muscles. We studied the effects of lubiprostone on the pacemaker potentials of colonic ICCs. We used the whole-cell patch-clamp technique to determine the pacemaker activity in cultured colonic ICCs obtained from mice. Lubiprostone hyperpolarized the membrane and inhibited the generation of pacemaker potentials. Prostanoid $EP_1$, $EP_2$, $EP_3$, and $EP_4$ antagonists (SC-19220, PF-04418948, 6-methoxypyridine-2-boronc acid N-phenyldiethanolamine ester, and GW627368, respectively) did not block the response to lubiprostone. L-NG-nitroarginine methyl ester (L-NAME, an inhibitor of nitric oxide synthase) and 1H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ, an inhibitor of guanylate cyclase) did not block the response to lubiprostone. In addition, tetraethylammonium (TEA, a voltage-dependent potassium [$K^+$] channel blocker) and apamin (a calcium [$Ca^{2+}$]-dependent $K^+$ channel blocker) did not block the response to lubiprostone. However, glibenclamide (an ATP-sensitive $K^+$ channel blocker) blocked the response to lubiprostone. Similar to lubiprostone, pinacidil (an opener of ATP-sensitive $K^+$ channel) hyperpolarized the membrane and inhibited the generation of pacemaker potentials, and these effects were inhibited by glibenclamide. These results suggest that lubiprostone can modulate the pacemaker potentials of colonic ICCs via activation of ATP-sensitive $K^+$ channel through a prostanoid EP receptor-independent mechanism.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 1996.12a
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• pp.70-70
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• 1996

The cytotoxicological effect of Bt 1-endotoxin, well-known as a bioinsecticide, was investigated on ion channel of insect cell lines. This study attempted to evaluted the specificity by simple experiment to measure the cell swelling using lepidopteran cell lines in isotonic solution containing only one cation. Cell swelling was stimulated in KCI-sucrose isotonic solution as well as TC-100 media containg in solubilized crystal 5-endotoxin. It suggested that the cell swelling by Bt toxin have a relation to K+ channel. The cell swelling may be due to the stimulation K+ influx and simultaneously the penetration of H2O induced by Bt toxin, because the stimulation of swelling was observed with the solubilized toxin in KCI-sucrose isotonic solution, but not in sucrose isotonic solution. Moreover the specific K+ channel blocker, such as 4-arnjnopyrimidine(4-AP) and ouabain, showed the significant effect on the cell swelling induced by Bt toxin. The increasement of the cell swelling induced by 4-AP suggested to be caused by the block of K+ efflux through K+ leak channels. The inhibition of cell swelling by ouabain, which is the well-known inhibitor of Na+, K+-ATPase, suggested to be due to decreasement of K+ influx following diminishment of Na+, K+-ATPase activities.

• Animal cells and systems
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• v.1 no.2
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• pp.329-335
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• 1997

The final pattern of the skeletal muscle of a vertebrate depends on the position-specific behavior of the muscle precursor cells during early developmental process and the abdominal muscle is made of cells which migrate a relatively long distance from their original tissue, myotome of dorsal mesoderm. We report the spatia-temporal migration pattern of abdominal muscle in Xenopus laevis by in situ hybridization and immunohistological studies. Shortly after hatching tadpole stage (stage 31/32), a group of myotomal cells detaches from the lower tip of the second somite and migrates ventrally to the lower position of abdomen. At stage 34/35, a second cell group migrates away from the third somite. Total 7 myotomal cell groups migrate ventrally one by one from the second to eighth myotome along their own pathways through the cell free space located between epidermis and subepidermal layer of the abdomen. During migration, the sizes of the cell groups (abdominal muscle anlagens) are increased to several tens fold. Around stage 40 all the abdominal muscle anlagens reaches their final positions and are interconnected side by side rostrocaudally. They are also connected to other types of muscles, forming a large multisegmented abdominal muscle. Heat shock study suggests that the disruption of segmentation of somites does not block the detachment of abdominal muscle anlagen, though the treatment gave stage- and dosagedependent effects on the migration speed.

• Bulletin of the Korean Chemical Society
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• v.27 no.2
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• pp.281-285
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• 2006

Microbial fuel cells (MFC) stacked with bipolar plates have been constructed and their performance was tested. In this design, single fuel cell unit was connected in series by bipolar plates where an anode and a cathode were made in one graphite block. Two types of bipolar plate stacked MFCs were constructed. Both utilized the same glucose oxidation reaction catalyzed by Gram negative bacteria, Proteus vulgaris as a biocatalyst in an anodic compartment, but two different cathodic reactions were employed: One with ferricyanide reduction and the other with oxygen reduction reactions. In both cases, the total voltage was the mathematical sum of individual fuel cells and no degradation in performance was found. Electricity from these MFCs was stored in a supercapacitor to drive external loads such as a motor and electric bulb.

• Journal of Life Science
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• v.16 no.1
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• pp.12-16
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• 2006

Genetic alternation of Brca1 predispose of breast and ovarian cancer. Brca1 plays critical role in cell cycle regulation following DNA damage. Previous studies revealed that Brca1 plays an important role in S phase and G2/M checkpoint regulation. However, whether Brca1 involves in spindle checkpoint is unclear. In this study, the role of Brca1 in cell cycle response following nocodazole, which is a reagent that depolymerizes microtubules and activates the spindle checkpoint, has been examined using wild type $p53^{-/-}\;and\;p53^{-/-}Brca1^{-/-}$ mouse embryonic fibroblasts (MEFs). While wild type and Brca1-proficient MEFs showed an acute mitotic arrest, Brca1-deficient MEFs failed to arrest at mitotic phase in response to nocodazole treatment. In double-thymidine block and nocodazole treatment experiment, a portion of $p53^{-/-}\;Brca1^{-/-}$ MEFs were clearly by-passed nocodazole induced mitotic arrest. Consistent with this, in morphologic analysis, $p53^{-/-}\;Brca1^{-/-}$ MEFs showed growing cell morphology after nocodazole treatment. Taken together, these results suggest that Brca1 protein is an important component for normal induction of spindlecheckpoint and impairment of Brca1 function could induce dysregulation of mitotic cell cycle that ultimately results in genomic instability.

• YAKHAK HOEJI
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• v.51 no.6
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• pp.482-489
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• 2007

Kaempferitrin, isolated from Kenaf (Hibiscus cannabinus), was examined to evaluate its modulatory effects on antigen-presenting cell functions of macrophages/monocytes such as phagocytosis of foreign materials, up-regulation of costimulatory molecules (CD40, CD80 and CD86), adhesion molecule activation, and antigen processing and presentation. Kaempferitrin strongly blocked up-regulation of CD40, CD80 and CD86, but not pattern recognition receptor (PRR) (e.g., TLR2). It also suppressed functional activation of CD29 (${\beta}1$-integrins), as assessed by cell-cell adhesion assay, required for T cell-antigen-presenting cell (APC) interaction. Furthermore, this compound did not block a simple activation of CD29, as assessed by cell-fibronectin adhesion assay. However, the compound did not diminish phagocytic uptake, an initial step for antigen processing, and ROS generation in RAW264.7 cells. In particular, to understand molecular mechanism of kaempferitrin-mediated inhibition, the regulatory role of LPS-induced signaling events was examined using immunoblotting analysis. Interestingly, this compound dose dependently suppressed the phosphorylation of $I{\kappa}B{\alpha}$, Src, Akt and Syk, demonstrating that it can negatively modulate the activation of these signaling enzymes. Therefore, our data suggested that kaempferitrin may be involved in regulating APC function-relevant immune responses of macrophages and monocytes by regulating intracellular signaling.

• The Journal of the Acoustical Society of Korea
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• v.18 no.3E
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• pp.44-48
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• 1999

The CMOS four-quadrant analog multiplier for low-voltage low-power applications are presented in this thesis. The circuit approach is based on the characteristic of the LV (Low-Voltage) composite transistor which is one of the useful analog building block. SPICE simulations are carried out to examine the performances of the designed multiplier. Simulation results are obtained by 0.6㎛ CMOS parameters with 2V power supply. The basic configuration of the multiplier is the CMOS Gilbert cell with two LV composite transistors. The linear input range of the multiplier is over ±0.4V with a linearity error of less than 1.3%. The measured -3dB bandwidth is 288MHz and the power dissipation is 255 ㎼.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.175-177
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• 2006

Here we report an enhanced flexoelectric switching in a self-assembled system of smectic liquid crystal and some specific dopant. The assembled unit block seemed to have electric dipole and as a result induces large flexoelectric polarization due to its asymmetric shape and shows fast switching to the electric field. The unit blocks are oriented in a helical fashion in the cell with large gap (${\sim}5{\mu}m$) and shows selective reflection property. In the thin cell (${\sim}2{\mu}m$), the unit blocks are aligned homeotropically on the bare ITO substrate with no surface treatment and shows fast decaying time.

• The Korean Journal of Cytopathology
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• v.4 no.2
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• pp.133-139
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• 1993

A case of presacral chordoma in a 55-year-old male diagnosed by aspiration biopsy cytology Is reported. Cytologically, three cell types were recognized in a mucoid background. large, mononucleated or binucleated physaliphorous cells with vacuolated bubbly cytoplasm; small, uniform and rounded non-vacuolated cells; and cells with microvacuolated and plump cytoplasm. The diagnosis of chordoma was possible because typical radiological and cytomorphological features were supported by the results of special staining and immunohistochemical staining with the cell block specimen obtained from the fine needle aspiration.

• KSBB Journal
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• v.5 no.3
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• pp.195-200
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• 1990

The growth behavior of recombinant Escherichia coli cells having plasmid pIF-III-B, which carries human alpha-interferon gene under the control of lpp promoter, lac promoter and lac operator, was studied by using of various E. coli host strains. Expression of the alpha-IFN gene is controllable by using inducer IPTG because the plasmid also contains lacI gene which produces lac regressors. The repressors block the transcription of alpha-IFN gene. There were considerable differences in cell growth according to the host strains used. Cell growth was inhibited not only by plasmid pIF-III-B itself but also by the induction of alph-a-IFN gene expression. Growth inhibition caused by the plasmid itself was more serious than that caused by the induction of alpha-IFN gene expression.