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Gsa 유전자의 돌연변이가 쥐의 소마토스타틴 수용체 유전자의 발현에 미치는 효과
양인명,박승준,장호강,이군자,오승준,김성운,김진우,김영설,최영길 대한내분비학회 1999 Endocrinology and metabolism Vol.14 No.4
Background: The growth hormone (GH)-secreting pituitary adenoma with mutation of Gsa gene (gsp oncogene) is known to show a higher response to somatostatin. The mechanism for the higher response is unclear. We previously demonstrated that transcription of the rat somatostatin receptor (SSTR) gene was increased by cAMP. Therefore, we investigated whether the mutation of Gsa gene can increase SSTR gene expression. Methods: The mutant Gsa expressing plasmid of which arginine of codon 201was replaced with histidine was transfected transiently and permanently into GH3 cells. cAMP and rat GH were measured by radioimmunoassay. mRNA expression of the rat SSTR2 was determined by a semiquantitative RT-PCR. Results: The intracellular cAMP production was increased by 1.8 folds in the transiently transfected cells and by 1.5 folds in permanently transfected cells compared to those in the cells transfected with the vehicle plasmid, plasmid expressing the wild type or the plasmid expressing the silent mutant of codon 226. The transcriptional activation by cAMP response element of somatostatin.gene was also increased by 2 folds 24 hours after transient transfection and by 3.5 folds in the permanently transfected cells. The transcriptional activation was not enhanced by forskolin in the transiently transfected cells, whereas it was more remarkably inhibited by somatostatin compared to that in the other transfected cells. The expression of SSTR2 was increased by 1.8 folds 24 hours after transfection in the transiently transfected cells and by 3 folds in the permanently transfected cells, and it was not enhanced by forskolin and isobutylmethylxanthine. The secretion of GH from the transiently transfected cells was not significantly higher than that from the wild type-expressing cells, but it was higher in the permanently transfected cells. The suppression of GH by somatostatin was more prominent in the permanently transfected cells compared to the other transfected cells. Conclusion: This study suggests that a higher expression of SSTR induced by the mutant Gsa may be a mechanism by which gsp-positive adenomas showed a higher response to somatostatin (J Kor Soc Endocrinol 14:657-666, 1999).
Engineering performance of barristors by varying the thickness of WS<sub>2</sub>
Choi, D.H.,Lee, J.H.,Kim, H.C.,Lee, H.B.,Jeoung, N.B.,Park, D.H.,Kim, H.,Jhang, S.H.,Lee, S.W.,Chung, H.J. Elsevier 2017 Current Applied Physics Vol.17 No.1
<P>We have investigated the performances of barristors with a graphene-tungsten disulfide (WS2) junction by varying the thickness of WS2 and gate oxide. On-current density (J(ON)) and on-and off-current ratio (J(ON)/J(OFF)) increases, and sub-threshold swing (V-SS) decreases with the WS2 thickness. Also, barristors with thicker WS2 required less workfunction shift, to switch the barristors. Therefore, unlike the traditional devices, VSS of barristor with gate dielectric 300 nm was smaller than that of 90 nm, when the former is fabricated with thicker WS2 than the latter. Since materials properties of 2-dimensional semiconductors generally vary with their thickness, the thickness of 2D semiconductors could become a key parameter to engineer the performance of barristors with graphene and the 2D semiconductors. (C) 2016 Elsevier B. V. All rights reserved.</P>
Progress of physics studies in the Hanbit mirror device
kwang-il You,A. C. England,B. H. Park,D. C. Seo,D. K. Lee,H. G. Jhang,H. K. Na,J. Chung,J. G. Bak,J. H. Lee,J. H. Yeom,J. S. Hong,K. K. Choh,M. K. Park,S. G. Lee,S. H. Seo,S. J. Yoo,S. S. Kim,S. W. Yo 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.III
The Hanbit is a complex mirror device that has a slot and a double half-turn antennas in the central cell to launch high power ion cyclotron resonance frequency range waves for plasma production, heating, and stabilization. However, there is no other device, such as a neutral beam injector, to heat the plasma ions. Hanbit also has three low-power supplies to launch electron cyclotron resonance frequency range waves for heating electrons. Under these circumstances, the main physics study in the Hanbit device has been devoted to RF-wave and plasma interaction studies, including MHD stabilization by using only the RF waves. In this paper, we briefly report the main results of the RF-heating research, MHD stability studies and discharge analysis during the past few years, as well as the future plans.
Progress in the Study of RF Heating and Stabilization on HANBIT Mirror Device
Kwon, M.,Bak, J. G.,Choh, K.,Choi, J. H.,Choi, J. W.,England, A. C.,Hong, J. S.,Jhang, H. G.,Kim, J. Y.,Kim, S. S.,Ko, W. H.,Lee, D. K.,Lee, J. H.,Lee, S. G.,Lee, H. G.,Lho, T.,Na, H. K.,Park, B. H.,P Informa UK (TaylorFrancis) 2005 Fusion science and technology Vol.47 No.1
Stabilization of Interchange Modes in Mirror Plasmas by a Nonlinear rf-Plasma Wave Coupling Process
Jhang, Hogun,Lee, S. G.,Kim, S. S.,Park, B. H.,Bak, J. G. American Physical Society 2005 Physical review letters Vol.95 No.3
<P>Experimental and theoretical studies are made of the consequences of a nonlinear coupling process between pump rf waves and interchange modes in mirror plasmas. It is demonstrated that the interchange-stable operation window exists depending on the applied rf power and gamma=omega(0)/Omega(i), where omega(0) (Omega(i)) is the angular frequency of the applied rf wave (ion cyclotron frequency). Results are shown that the nonlinear wave coupling process gives rise to the operation window near the resonance (gamma approximately equal to 1), which is elucidated by theoretical analyses combined with full rf wave simulations.</P>
Impact of zonal flows on edge pedestal collapse
Jhang, Hogun,Kaang, Helen H.,Kim, S.S.,Rhee, T.,Singh, R.,Hahm, T.S. International Atomic Energy Agency 2017 Nuclear fusion Vol.57 No.2
<P>We perform a computational study of the role of zonal flows in edge pedestal collapse on the basis of a nonlinear three-field reduced magnetohydrodynamic (MHD) model. A dramatic change of dynamics takes place when ideal ballooning modes are completely stabilized. Analyses show that a new instability is developed due to a strong excitation of zonal vorticity, resulting in a series of secondary crashes. The presence of subsidiary bursts after a main crash increases the effective crash time and energy loss. These simulation results resemble the behavior of compound edge localized modes (ELMs). Analyses in this paper indicate that a complete understanding of ELM crash dynamics requires the self-consistent inclusion of nonlinear zonal flows-MHD interaction and transport physics.</P>
Jhang, K.A.,Lee, E.O.,Kim, H.S.,Chong, Y.H. Elsevier Science Pub. Co 2014 NEUROBIOLOGY OF AGING Vol.35 No.11
Pathophysiological evidence correlating locus ceruleus neuron loss with increased Alzheimer's disease pathology suggests that norepinephrine (NE) is neuroprotective. Here, we evaluated the effects of NE on amyloid-β (Aβ)1-42-induced neurotoxicity and determined how NE exerts its actions in human SK-N-SH neurons. NE protected SK-N-SH cells against Aβ1-42-induced neurotoxicity only after a 4-hour treatment. The ability of NE to reduce Aβ1-42-induced neurotoxicity was independent of the adrenoceptor signaling pathway. Notably, NE downregulated Aβ1-42-mediated increases in intracellular reactive oxygen species (ROS) production. However, NE did not affect Aβ1-42-induced activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) redox signaling pathway, known to be involved in oxidative stress. Among the antioxidants tested, N-acetyl cysteine and glutathione, which are not only ROS scavengers but also thiol-reducing agents, mimicked the protective effects of NE. Consistently, Kelch-like ECH-associating protein 1 inhibitors, which activated the Nrf2 pathway, failed to decrease Aβ1-42-induced ROS generation and elicited no protection against Aβ1-42. Taken together, these findings suggest that NE could exert neuroprotective function against Aβ1-42 via redox cycling and reduction of intracellular oxidative stress regardless of downstream activation of the Nrf2 pathway.