• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.6
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• pp.72-80
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• 1996

This paper presetns the development of a SSPA operating at KU-band(14~14.5 GHz) in order of replace TWTA used in the terrestria transponder of a satellite communication. The driving stage of SSPA uses internally matched 2W, 4W, 8W FET and the power stage is coupled with two internally matched 8W FET by branch-line cominer. The SSPA is fabricated with oth the RF circuit and the bias circuitry operating temperature compensation, regulation and sequence on aluminum housing. The SSPA testing resutls implemented in this way show 24.8$\pm$1dB small-signal gain, 41dBm P1dB power, a typical two tone C/IM3, -33dBc with single carrier backed off 6dB from p1dB, and gain stability over temeprature (-30~50)$\pm$1dB.

• Journal of Marine Bioscience and Biotechnology
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• v.1 no.4
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• pp.243-251
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• 2006

Dideoxypetrosynol A, a polyacetylene from the marine sponge Petrosia sp., is known to exhibit significant selective cytotoxic activity against a small panel of human tumor cell lines, however, the mechanisms of which are poorly understood. In the present study, it was investigated the further possible mechanisms by which dideoxytetrosynol A exerts its anti-proliferative action in cultured human leukemia cell line U937. We observed that the proliferation-inhibitory effect of dideoxypetrosynol A was due to the induction of G1 arrest of the cell cycle and apoptosis, which effects were associated with up-regulation of cyclin D1 and down-regulation of cyclin E without any change in cyclin-dependent-kinases (Cdks) expression. Dideoxypetrosynol A markedly induced the levels of Cdk inhibitor p16/INK4a expression. Furthermore, down-regulation of phosphorylation of retinoblastoma protein (pRB) by this compound was associated with enhanced binding of pRB and the transcription factor E2F-1. The increase in apoptosis was associated with a dose-dependent up-regulation in pro-apoptotic Bax expression and activation of caspase-3 and caspase-9. Dideoxytetrosynol A decreased the levels of cyclooxygenase (COX)-2 mRNA and protein expression without significant changes in the levels of COX-1, which was correlated with a decrease in prostaglandin E2 (PGE2) synthesis. Furthermore, dideoxytetrosynol A treatment markedly inhibited the activity of telomerase, and the expression of human telomerase reverse transcriptase (hTERT), a main determinant of the telomerase enzymatic activity, was progressively down-regulated by dideoxytetrosynol A treatment in a dose-dependent fashion. Taken together, these findings provide important new insights into the possible molecular mechanisms of the anti-cancer activity of dideoxytetrosynol A.

• Journal of Life Science
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• v.19 no.7
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• pp.871-877
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• 2009

We investigated the effects of sodium butyrate, a histone deacetylase inhibitor, on the cell cycle progression in human monocytic leukemia U937 cells. Exposure of U937 cells to sodium butyrate resulted in growth inhibition, G1 arrest of the cell cycle and induction of apoptosis in a dose-dependent manner as measured by MTT assay and flow cytometry analysis. The increase in G1 arrest was associated with the down-regulation in cyclin D1, E, A, cyclin-dependent kinase (Cdk) 4 and 6 expression, and up-regulation of Cdk inhibitors such as p21 and p27. Sodium butyrate treatment also inhibited the phosphorylation of retinoblastoma protein (pRB) and p130, however, the levels of transcription factors E2F-1 and E2F-4 were not markedly modulated. Furthermore, the down-regulation of phosphorylation of pRB and p130 by this compound was associated with enhanced binding of pRB and E2F-1, as well as p130 and E2F-4, respectively. Overall, the present results demonstrate a combined mechanism involving the inhibition of pRBjp130 phosphorylation and induction of Cdk inhibitors as targets for sodium butyrate that may explain some of its anti-cancer effects in U937 cells.

• Food Science and Industry
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• v.55 no.3
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• pp.276-283
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• 2022

Vitamin D is a fat-soluble vitamin helps to retain calcium and phosphorus but also has shown to affect immune regulation and homeostasis. In humans, vitamin D3 and vitamin D2 and their metabolite has intensively studied in both innate and adaptive immune system that they are important to regulate overwhelmed inflammation. The vitamin D receptor is a nuclear hormone receptor which regulate various downstream target gene expressions as a transcription factor related to metabolism, immune regulation, etc. Vitamin D deficiency is a high-risk factor for inflammatory diseases like autoimmune disease and allergy. In addition, reduced vitamin D seem to correlate with susceptibility to the virus infection such as HIV and COVID-19. In this review, we will summarize up-to-date vitamin D's role in various immune cells, immune regulatory functions during autoimmune, allergic, and infectious diseases. We will also discuss about vitamin D supplement effects in human trial studies for COVID-19.

• BMB Reports
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• v.49 no.2
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• pp.81-92
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• 2016

Insulin/insulin-like growth factor (IGF)-1 signaling (IIS) pathway regulates aging in many organisms, ranging from simple invertebrates to mammals, including humans. Many seminal discoveries regarding the roles of IIS in aging and longevity have been made by using the roundworm Caenorhabditis elegans and the fruit fly Drosophila melanogaster. In this review, we describe the mechanisms by which various IIS components regulate aging in C. elegans and D. melanogaster. We also cover systemic and tissue-specific effects of the IIS components on the regulation of lifespan. We further discuss IIS-mediated physiological processes other than aging and their effects on human disease models focusing on C. elegans studies. As both C. elegans and D. melanogaster have been essential for key findings regarding the effects of IIS on organismal aging in general, these invertebrate models will continue to serve as workhorses to help our understanding of mammalian aging.

• Journal of Power Electronics
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• v.14 no.2
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• pp.282-291
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• 2014

This paper presents a detailed theoretical analysis and performance assessment of the capacitor voltage balancing strategies for staircase modulated modular multilevel converters (MMC) in terms of the algorithm structures, voltage balancing effect, and switching frequency. A constant-frequency redundancy selection (CFRS) method with minimal switching loss is proposed and the function realization of specific modules of the algorithm is given. This method is simple and efficient in both switching frequency and regulation capacity. Laboratory results show very good agreement with the theoretical analysis and numerical simulations.

• Proceedings of the Korean Society of Toxicology Conference
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• 2002.11b
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• pp.135-135
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• 2002

Cyclooxygenase-2 (COX-2) is an inducible enzyme expressed in response to a variety of cytokines and other proinflammatory stimuli. It has been known that aberrant up-regulation of COX-2 is associated with resistance to apoptosis.(omitted)

• Journal of Periodontal and Implant Science
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• v.33 no.3
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• pp.415-437
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• 2003

Ginseng Radix(GR) had been used widely from oriental medicine and the effects of it have been investigated by many researchers. The purpose of present study was to investigate the effects of GR on the cell cycle progression and its molecular mechanism in human fetal osteoblast. The results were as follows. Increased cell proliferation was observed in cells exposed to 100 ng/ml, 10 ng/ml of GR-1 at 12 hours and 24 hours, 1 ${\mu}g$/ml of GR-1 at 48 hours, and 100 ${\mu}g$/ml, 10 ${\mu}g$/ml of GK-2 at 12 hours, all treatment groups of GR-2 at 24 hours(p<0.05). S phase and G1 phase was increased in the group of treated with 100 ng/ml of GR-1, with 10 ${\mu}g$/ml and 1 ${\mu}g$/ml of GR-2, with 100 ${\mu}g$/ ml and 10 ${\mu}g$/ml of GR-3 in the cell cycle analysis. The cell cycle regulation protein levels of Cyclin D1, Cyclin E, CDK 2. CDK 4 and CDK 6 were increased in the group of treated with 1 ${\mu}g$/ml and 100 ng/ml of GR-1, with 10 ${\mu}g$/ml and 1 ${\mu}g$/ml of GR-2, with 100 ${\mu}g$/ ml and 10 ${\mu}g$/ml of GR-3. On the other hand, p21 was decreased in the treatment group with 1 ${\mu}g$/ml and 100 ng/ml of GR-1, with 10 ${\mu}g$/ml and 1 ${\mu}g$/ml of GR-2, 10 ${\mu}g$/ml of GR-3, and p53 and p16 was decreased in the treatment group with 100 ng/ml of GR-1, 100 ${\mu}g$/ml and GR-3 and pRb was decreased in the all treatment groups except 1 ${\mu}g$/ml of GR-1. These results suggested that GR increases the cell proliferation and the cell cycle progression in human fetal osteoblast, which is linked to increased cell cycle regulation protein levels of Cyclin D1 , Cyclin E, CDK 2, CDK 4, CDK 6 and decreased cell cycle regulation protein levels of p21, pRb.

• Development and Reproduction
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• v.19 no.1
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• pp.11-17
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• 2015

This study investigated possible involvement of photoperiodic regulation in reproductive endocrine system of female olive flounder. To investigate the influence on brain-pituitary axis in endocrine system by regulating photoperiod, compared expression level of Kisspeptin and sbGnRH mRNA in brain and FSH-${\beta}$, LH-${\beta}$ and GH mRNA in pituitary before and after spawning. Photoperiod was treated natural photoperiod and long photoperiod (15L:9D) conditions from Aug. 2013 to Jun. 2014. Continuous long photoperiod treatment from Aug. (post-spawning phase) was inhibited gonadal development of female olive flounder. In natural photoperiod group, the Kiss2 expression level a significant declined in Mar. (spawning period). And also, FSH-${\beta}$, LH-${\beta}$ and GH mRNA expression levels were increasing at this period. However, in long photoperiod group, hypothalamic Kiss2, FSH-${\beta}$, LH-${\beta}$ and GH mRNA expression levels did not show any significant fluctuation. These results suggest that expression of hypothalamic Kiss2, GtH and GH in the pituitary would change in response to photoperiod and their possible involvement of photoperiodic regulation in reproductive endocrine system of the BPG axis.

• Restorative Dentistry and Endodontics
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• v.21 no.1
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• pp.366-374
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• 1996

The purpose of this study was to investigate whether D-myo-inositol-l,2,6-trisphosphate (PP56) can effectively antagonize vasoconstriction caused by neuropeptide Y in the dental pulp, and to understand involvement of neuropeptide Y in the regulation of microcirculation in the dental pulp with the aim of elucidating neurogenic inflammation. Experiments were performed on 7 cats anesthetised with sodium pentobarbital, and neuropeptide Y and a neuropeptide Y antagonist PP56 were injected close intra-arterially into the dental pulp. The probe of laser Doppler flowmeter was placed on the buccal surface of ipsilateral canine teeth to the drug administration and pulpal blood flow was measured. Intra-arterial injection of neuropeptide Y (1.3-$2.0\;{\mu}g$/kg) resulted in pulpal blood flow decrease of $37.73{\pm}5.73%$(mean${\pm}$SEM) (n=9). Intra-arterial injection of PP56(0.3 mg/kg) alone changed pulpal blood flow little by 1.03 % reduction. The effect of neuropeptide Y in the presence of PP56 resulted in significantly less decreases in pulpal blood flow ranging from $27.17{\pm}5.37$ to $16.63{\pm}3.48%$ from control as compared with neuropeptide Y alone(n = 13). In effect, PP56 attenuated pulpal blood flow caused by neuropeptide Y. Results of the present study have provided evidences that a non-peptide PP56 is capable of antagonizing vasoconstriction caused by neuropeptide Y in the feline dental pulp. In addition, they show functional evidences that neuropeptide Y plays an active role in modulating the microcirculation of the dental pulp.