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Rapid Decrease of Phospholipase C Activity in NIH3T3 Cells by UV - irradiation
Joe, Cheol O,Giltsu Tchoi,Lee, Tae Hoo 한국유전학회 1989 Genes & Genomics Vol.11 No.4
Intracellular level of inositol phosphates was examined in UV-damaged NIH3T3 cells. The levels of three classes of inositol phosphates, inositol monophosphate, inositol bisphosphate and inositol triphosphate were dramatically dropped in the fibroblasts which were irradiated with 10J/M² of UV radiation and postincubated for 3 mins. Sudden drop of phospholipase C activity was observed in UV-damaged fibroblasts. Decreased inositol phosphate metabolism and phospholipase C activity by UV-irradiation were dose-dependent, When UV-damaged NIH3T3 cells were posttreated with phorbol 12-myristate 13-acetate (PMA), protein kinase C activator, unscheduled DNA synthesis was markedly inhibited, and maximal level of inhibition was observed with 50 nM PMA. However no inhibition of replicative DNA synthesis was observed. These results suggest that inactivation of protein kinase C is the early event of DNA repair synthesis induced by UV DNA damage.
Joe, Cheol O,Kang, Ke Won,Koo, Soo Kyung 한국유전학회 1993 Genes & Genomics Vol.15 No.2
Phosphoproteins were analyzed in human pre-erythrocyte leukemia cells transitting G_0 to S phase of the cell cycle. The protein of 110kDa of molecular weight was heavily phosphorylated in cells subjected to growth arrest at G_0 phase. An altered protein phosphorylation pattern was observed upon growth stimulation by refeeding serum to the cells. The newly phosphorylated proteins of 100 and 120kDa were detected during the transition period from G_0 to S phase entry. Upon the growth stimulation, the intracellular levels of Ca^(2+) and IP₃ second messenger molecules were suddenly elevated suggesting that signal cascades transmitted through the messenger molecules regulate the phosphorylation of specific proteins which are crucial for the maintenance of cell cycling.
Isolation and Characterization of Epidermal Mucus from hirudo nipponia
Joe, Cheol O,Kang, Ke Won,Lee, Ju Yun 생화학분자생물학회 1981 BMB Reports Vol.29 No.3
The epidermal organ of the leech contains a complex glycoprotein molecule of mucus. The mucus excreted from annelids plays significant role in protection against desiccation and parasites. Mucus from the Korean native leech, H. nipponia, was investigated for biochemical characteristics for possible development of biomaterials of cosmetic and pharmaceutical agents. The leech skin mucus was heavily glycosylated mucin-like protein with a high molecular weight comprised 80% carbohydrate and 20% protein. Threonine, serine, and glycine were the major components of the isolated protein and these accounted for 50% of total amino acids. The carbohydrate portion contained glucosamine, galactosamine, galactose, glucose, mannose and sialic acid in oligosaccharide form linked with threonine and serine residues of the glycoprotein.
Joe, Cheol O 한국유전학회 1986 Genes & Genomics Vol.8 No.4
Cellular levels of DNA polymerase alpha and beta enzyme activities have been analyzed in (±)r-7, t-8-dihydroxy-t-9, 10-epoxy-7, 8, 9, 10-tetrahydrobenzo (a)-pyrene (BPDE) treated mouse sarcoma cells. Two subsequent waves of DNA polymerases were observed during unscheduled DNA synthesis initiated by BPDE. The first wave occurs within 3 hrs after removal of carcinogen from the media with the increase in DNA polymerase alpha activity, and the second one was the increase of DNA polymerase beta which were observed in the cells allowed to repair the DNA damage for 9 hrs. The time courses of repair synthesis following treatment of mouse sarcoma cells with 400 ng/㎖ of BPDE as measured by ³H-thymidine incorporation for 1 hr shows biphasic curve, which may coincide with the faster gap filling capacity of DNA polymerase alpha than DNA polymerase beta. Data presented here suggest that both activities of polymerase alpha and beta are required to resynthesize the excised DNA damage, and that DNA polymerase alpha is the major enzyme involved in the resynthesis of DNA damage after endonuclease nicking step while DNA polymerase beta fill the rest of the gap thereafter.
Kim, Cheol-Ju,Ko, Seuk-Beum,Lee, Jong-Myung,Jeon, Il-Cheol,Lee, Dong J.,Shin, Kook-Joe Korean Chemical Society 1988 Bulletin of the Korean Chemical Society Vol.9 No.6
The explicit form of time correlation function between fluctuating concentrations is obtained for the model of metabolic system with negative feedback near a stable(or marginally stable) steady state.
The Critical Phenomena of a Model for the Metabolic Control System with Positive Feedback
Kim, Cheol-Ju,Lee, Dong- J.,Shin, Kook-Joe,Lee, Jong-Myung,Ko, Seuk-Beum,Jeon, Il-Cheol Korean Chemical Society 1989 Bulletin of the Korean Chemical Society Vol.10 No.5
The static and dynamic phenomena of a model for the metabolic control system with positive feedback are discussed with the static and dynamic renormalization group theory. Then, the explicit results for the static and dynamic exponents are obtained up to the second order of ${\varepsilon}$-expansion, ${\varepsilon}$ being 4-d, where d is the space dimensionality of the system.
Eui-Cheol Nho,In-Dong Kim,Cheol-Je Joe,Tae-Won Chun,Heung-Geun Kim 전력전자학회 2001 ICPE(ISPE)논문집 Vol.2001 No.10
This paper describes an improved short-circuit protection method with a boost type rectifier using a multilevel ac/dc power converter The output dc power of the proposed converter can be disconnected from the load within several hundred microseconds at the instant of short-circuit fault Once the fault has been cleared the dc power is reapplied to the load The rising time of the dc load voltage is as small as several hundred microseconds, and there is no overshoot of the dc voltage because the dc output capacitors hold undischarged state The converter, which employs the proposed method, has the characteristics of a simplified structure, reduced cost, weight, and volume compared with a conventional power supply, which has frequent output short-circuits. Experimental results are presented to verify the usefulness of the proposed converter.<br/>