• Journal of Life Science
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• v.11 no.4
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• pp.362-370
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• 2001

Regulation of cell proliferation is a complex process involving the regulated expression and /or modification of discrete gene products. which control transition between different stages of the cycle. The purpose of this short review is to provide an overview of somatic cell cycle events and their controls. Cycline have appeared as major positive regulators in this network, because their association to the cyclin-dependent kinases(Cdks) allows the subsequent activation on the Cdk/cyclin complexes and their catalatic activity. In mammalian cells, early to mid G1 progression and late G1 progression leading to S phase entry are directed by D-type cyclins-Cdk4, 6 and cyclin E-Cdk 2 both of which can phosphorylate the retinoblastoma protein (pRB). pRB is a transcriptional repressor which, in its unphosphorylated state, binds to members of the E2F transcription factor family and blocks E2F-dependent transcription of genes controlling the G1 to S phase transition an subsequent DNA synthesis. Cyclin A is produced in late G1 and expressed during S and G2 phae, and expression of B-type cyclins is typically maximal during the G2 to M phase transition and it controls the passage through M phase. They primarily associate with the activate Cdk2, and Cdc2, respectively. On the other hand, the Cdk inhibitors negatively control the activity of C아/cyclin complex by coordinating internal and/or external signals and impending proliferation at several key checkpoints. These current and further findings will provide novel approaches to understanding and treating major diseases.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.83-86
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• 1996

In this paper we study the problem of augmenting a physical network to improve the topology for new survivable network architectures. We are given a graph G=(V,E,F), where V is a set of nodes that represents transmission systems which be interconnected by physical links, and E is a collection of edges that represent the possible pairs of nodes between which a direct transmission link can be placed. F, a subset of E is defined as a set of the existing direct links, and E/F is defined as a set of edges for the possible new connection. The cost of establishing network $N_{H}$=(V,H,F) is defined by the sum of the costs of the individual links contained in new link set H. We call that $N_{H}$=(V,H,F) is feasible if certain connectivity constrints can be satisfied in $N_{H}$=(V,H,F). The computational goal for the suggested model is to find a minimum cost network among the feasible solutions. For a k edge (node) connected component S .subeq. F, we charactrize some optimality conditions with respect to S. By this characterization we can find part of the network that formed by only F-edges. We do not need to augment E/F edges for these components in an optimal solution. Hence we shrink the related component into a node. We study some good primal heuristics by considering construction and exchange ideas. For the construction heuristics, we use some greedy methods and relaxation methods. For the improvement heuristics we generalize known exchange heuristics such as two-optimal cycle, three-optimal cycle, pretzel, quezel and one-optimal heuristics. Some computational experiments show that our heuristic is more efficient than some well known heuristics.stics.

• International Journal of Oral Biology
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• v.35 no.2
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• pp.51-60
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• 2010

Few studies have evaluated the apoptosis-inducing efficacy of NaF on cancer cells in vitro but there has been no previous investigation of the apoptotic effects of NaF on human oral squamous cell carcinoma cells. In this study, we have investigated the mechanisms underlying the apoptotic response to NaF treatment in the YD9 human squamous cell carcinoma cell line. The viability of YD9 cells and their growth inhibition were assessed by MTT and clonogenic assays, respectively. Hoechst staining, DNA electrophoresis and TUNEL staining were conducted to detect apoptosis. YD9 cells were treated with NaF, and western blotting, immunocytochemistry, confocal microscopy, FACScan flow cytometry, and MMP and proteasome activity assays were performed sequentially. The NaF treatment resulted in a time- and dose-dependent decrease in YD9 cell viability, a dose-dependent inhibition of cell growth, and the induction of apoptotic cell death. The apoptotic response of these cells was manifested by nuclear condensation, DNA fragmentation, the reduction of MMP and proteasome activity, a decreased DNA content, the release of cytochrome c into the cytosol, the translocation of AIF and DFF40 (CAD) into the nucleus, a significant shift of the Bax/Bcl-2 ratio, and the activation of caspase-9, caspase-3, PARP, Lamin A/C and DFF45 (ICAD). Furthermore, NaF treatment resulted in the downregulation of G1 cell cyclerelated proteins, and upregulation of p53 and the Cdk inhibitor $p27^{KIP1}$. Taken collectively, our present findings demonstrate that NaF strongly inhibits YD9 cell proliferation by modulating the expression of G1 cell cycle-related proteins and inducing apoptosis via mitochondrial and caspase pathways.

• Journal of Environmental Health Sciences
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• v.29 no.2
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• pp.16-22
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• 2003

BBP (Butyl benzyl phthalate), a widely used plasticizer. can enter the food and environment as consequence of its manufacture, use, and disposal. BBP was found to be developmental and teratogenic or endocrine disrupting chemical in rats. The effects of BBP were investigated in female rats (P) and second generation (F1) via lactations. Sprague-Dawley were given BBP by oral administration at 0, 5, 10, 100, 1000 mg/kg on day 0 to 21 of lactation period. The results were as follows : At maternal findings, there were some significant changes (p<0.05) in relative organ weight, especially liver and uterus weight by BBP administration. In estrous cycle, high treated group was inclined to be proestrus or estrus compared to control group. BBP indues estrous cycle earlier than the control group. At fetal findings, there were some significant changes in relative liver and spleen weight, especially 100, 1000 mg/kg administered groups. The relative weight of ventral prostate was decreased, so it was represent to dose-response tendency. Parent rats (P) were detected monobenzyl phthalate (MBeP) 3.21~5.81 $\mu\textrm{g}$/ml in 100, 1000 mg/kg dose groups. MBeP of male and female fetuses (F1) were detected at the level of 1.21~2.63 $\mu\textrm{g}$/ml of serum. Male serum concentration oi MBeP was higher than the females'. Estrogen receptor $\alpha$ expression by BBP and bisphenol A in uterus and testis of F1 were studied. The ER$\alpha$ expression were increased in F1 male testis and female uterus. F1 male showed distint ER$\alpha$ expression, especially in the combined exposrue. Synergistic ER$\alpha$ expression was found by combined treatment group of BBP and bisphenol A. From the above results, it could be concluded that the effects of dams and F1 by BBP administration during lactation period were estrogenic, and BBP can transfer to F1 via lactation, and make estrogenic at F1 reproductive organs.

• Journal of Microbiology and Biotechnology
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• v.12 no.3
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• pp.470-475
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• 2002

In the course of screening for a novel cell cycle inhibitor, a potent Cdk 1 inhibitor, HY558, was found from the culture broth of Penicillium minioluteum F558 isolated from a soil sample. The molecular ion of HY558 was identified at m/z 329 (MH+) with a molecular formula of $C_20H_44ON_2$. HY558 exhibited selective antiproliferative effects on various human cancer cell lines. Its $IC_50$ values were estimated to be 0.29 mM on HepG2, 0.30 mM on HeLa, 0.30 mM on HL6O, 0.33 mM on HT-29, and 0.25 mM on AGS cells. Interestingly, Hy558 demonstrated no antiproliferative effect with normal lymphocytes used as the control, and a low level of inhibition on the proliferation of A549 cancer cells. A flow cytometric analysis of HepG2 cells revealed an appreciable arrest of cells at the G1 and G2/M phases of the cell cycle following treatment with Hy558. furthermore, DNA fragmentation due to apoptosis was observed in HeLa cells treated with 0.46 mM of HY558.

• Communications of the Korean Mathematical Society
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• v.24 no.1
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• pp.127-144
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• 2009

Let f be a diffeomorphism of a compact $C^{\infty}$ manifold, and let p be a hyperbolic periodic point of f. In this paper we introduce the notion of $C^1$-stable inverse shadowing for a closed f-invariant set, and prove that (i) the chain recurrent set $\cal{R}(f)$ of f has $C^1$-stable inverse shadowing property if and only if f satisfies both Axiom A and no-cycle condition, (ii) $C^1$-generically, the chain component $C_f(p)$ of f associated to p is hyperbolic if and only if $C_f(p)$ has the $C^1$-stable inverse shadowing property.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.395-399
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• 2009

Advanced afterburner used in the most modernized gas turbine has new designing paradigm to cope with reinforced power density. The most distinct change is the designing trend to integrate fuel injectors and flame holder in order to manage higher temperature of inlet air. F414 and F110-GE-132 engine adopted this methodology and installed a variable nozzle utilizing CMC(Ceramic Matric Composite) material and active cooling of nozzle flap with ejector nozzle in order to enhance the life cycle of engine components and an economical aspect. These technological trends can be utilized for an advanced ramjet engine and combined cycle engine like TBCC.

• Journal of Photoscience
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• v.9 no.3
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• pp.65-70
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• 2002

In the rice leaves treated with methyl viologen (MV), the photochemical efficiency of PSII (or $F_{v/}$F $m_{m}$) was significantly decreased, and significant portion of the photoinactivation process was reversible during the dark-recovery. The dark-reactivation process was relatively slow, reaching its plateau after 2-2.5 h of dark incubation. The damaged portion of functional PSII was 13％, based on the value of I/ $F_{o}$- I/ $F_{m}$ after this dark-recovery period. The reversible photoinactivation process of PSII function in the MV-treated leaves consisted of a xanthophyll cycle-dependent development of NPQ and a xanthophyll cycle-independent process. The latter process was reversible in the presence of nigericin. As well as the increase in the values of Chl fluorescence parameters, the epoxidation process during the dark-recovery after the MV-induced photooxidation was very slow. These results suggest that the photooxidative effect of MV is partly protected by the down-regulation of PSII before inducing physical damages in core proteins of PSII.I.I.I.I.

• Journal of radiological science and technology
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• v.38 no.1
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• pp.31-38
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• 2015

$^{18}F-FDG$ PET/CT has been known a useful modality to diagnose high-glucose-using cells such as cancer cells by glucose metabolism of FDG. Mainly, FDG takes on cancer and inflammatory cells; however, there have been FDG uptakes on normal tissues by individual physiological characteristics, occasionally. Especially, in fertile females, unusual FDG uptake of breast changes as the menstrual cycle, and disturb diagnosis. Therefore, the study aimed to evaluate the change of breast FDG uptake in menstrual cycle on $^{18}F-FDG$ PET/CT. 160 females ($34{\pm}3.5$ years old) who do not undergo a gynecologic anamnesis and have regular menstrual cycle over the previous 6 months were examined. They were divided 4 groups (each 40 patients) as flow phase, proliferative phase, ovulatory phase and secretory phase using Pregnancy Calculator 0.14. and history taking. Discovery Ste (GE Healthcare, Milwaukee, Mi, USA) was used a s PET/CT. We analyzed SUVs on accumulated region on breast, and 3 nuclear medicine specialists did the Blind test. SUVs on the Breast were flow phase ($1.64{\pm}0.25$), proliferative phase ($0.93{\pm}0.28$), ovulatory phase ($1.66{\pm}0.26$) and secretory phase ($1.77{\pm}0.28$). It showed high uptake value in secretory, flow phase and ovulatory phase (p<0.05). In gross analysis, the accumulation of breast was divided into 3 grades as comparing with lung and liver. The breast's uptake was equal to lung (Grade I); between lung and liver (Grade II); equal to or greater than liver (Grade III). The results showed high uptake value in secretory, flow phase and ovulatory phase (p<0.05). In fertile females, FDG uptake of breast changed as menstrual cycle, and it available to diagnose breast disease. Therefore, we consider reducing false-negative finding of breast disease, by doing examination on appropriate period through history taking about individual menstrual cycle.

• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.1
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• pp.39-44
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• 2011

Purpose: $^{18}F$-FDG PET/CT has been known a useful modality to diagnose high-glucose-using cells such as cancer cells by glucose metabolism of FDG. Mainly, FDG takes on cancer and inflammatory cells; However, There have been FDG uptakes on normal tissues by individual physiological characteristics, occasionally. Especially, in fertile females, unusual FDG uptake of breast changes as the menstrual cycle, and disturb diagnosis. Therefore, the study aimed to evaluate the change of breast FDG uptake in menstrual cycle on $^{18}F$-FDG PET/CT. Materials and Methods: 160 females ($34{\pm}3.5$ years old) who do not undergo a gynecologic anamnesis and have regular menstrual cycle over the previous 6 months were examined, from March 2009 to February 2010. They were divided 4 groups (each 40 patients) as flow phase, proliferative phase, ovulatory phase and secretory phase using Pregnancy Calculator 0.14. and history taking. Discovery Ste (GE Healthcare, Milwaukee, Mi, USA) was used as PET/CT. We analyzed SUVs on accumulated region on breast, and 3 nuclear medicine specialists did the Blind test. Results: SUVs on the Breast were flow phase ($1.64{\pm}0.25$), proliferative phase ($0.93{\pm}0.28$), ovulatory phase ($1.66{\pm}0.26$) and secretory phase ($1.77{\pm}0.28$). It showed high uptake value in secretory, flow phase and ovulatory phase (p<0.05). In gross analysis, the accumulation of breast was divided into 3 grades as comparing with lung and liver. The breast's uptake was equal to lung (Grade I); between lung and liver (Grade II); equal to or greater than liver (Grade III). The results showed high uptake value in secretory, flow phase and ovulatory phase (p<0.05). Conclusion: In fertile females, FDG uptake of breast changed as menstrual cycle, and it available to diagnose breast disease. Therefore, we consider reducing false-negative finding of breast disease, by doing examination on appropriate period through history taking about individual menstrual cycle.