• 전자공학회논문지A
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• 제33A권6호
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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.

• 한국해양바이오학회지
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• 제1권4호
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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.

• 생명과학회지
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• 제19권7호
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• pp.871-877
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• 2009

대표적인 histone deacetylase inhibitor 저해제의 일종일 sodium butyrate에 의한 인체백혈병 U937세포의 증식 억제에 관한 기전 연구를 세포주기 조절 측면에서 조사하였다. MTT assay 및 flow cytometry 분석을 통하여 sodium butyrate의 처리 농도 증가에 따른 U937 세포의 증식억제는 세포주기 G1 arrest 및 apoptosis 유발에 의한 것임을 확인하였다. RT-PCR및 Western blotting 결과에서 sodium butrate에 의한 G1 arrest는 세포주기 G1기에서 S기로의 진입에 중요한 역할을 하는 cyclin D1, E, A, cyclin-dependent kinase (Cdk) 4 및 Cdk6발현의 저해와 p21 및 p27과 같은 Cdk inhibitor의 발현 증가와 연관성이 있었다. Sodium butyrate는 또한 retinoblastoma protein (pRB)및 p130 단백질의 인산화를 저해시켰으나, S기 진행에 중요한 전사조절인자인 E2F-1 및 E2F-4의 의 발현에는 큰 영향이 없었다. 그러나 sodium butyrate에 의한 pRB 및 p130단백질의 인산화 저해는 pRB와 E2F-1및 p130과 E2F-4와의 결합력을 증사시켰다. 본 연구의 결과는 U937세포의 증식억제에 pRB/p130 인산화 억제 및 Cdk inhibitors의 발현 증가가 중요한 역할을 하고있음을 보여주는 것으로, sodium butyrate의 항암기전 이해에 중요한 자료가 될 것이다.

• 식품과학과 산업
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• 제55권3호
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• pp.276-283
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• 2022

비타민D3는 칼슘 대사를 조절하며 뼈의 건강을 담당하는 중요한 호르몬이지만 다양한 면역세포에 작용하여 면역반응을 조절할 수 있다는 것이 알려지면서 자가면역질환, 알레르기질환, 감염 등 여러 질병과의 상관관계에 대한 관심이 증가되었다. 비타민D3의 활성 형태인 1,25(OH)2D3는 면역세포에 의해 전환될 수 있으며 핵-호르몬 수용체인 VDR과 결합하여 세포 내 다양한 유전자 발현을 조절함으로써, 세포의 형질과 기능을 바꿀 수 있다. 특히, 최근 다양한 연구를 통해 과도한 면역 반응을 조절하는 Treg 세포의 분화를 증가시키고 그 기능을 향상시키는 기전을 통해 염증성 사이토카인을 감소시키며, 외부 병원균을 제거할 수 있는 AMP의 생산을 유도함으로써 자가면역질환, 알레르기, 감염성 질환 등 다양한 질환에 긍정적 역할을 할 수 있음이 확인되었다. 특히, 최근 COVID-19 에 의한 글로벌 팬데믹을 경험하면서, 중증 질환 및 사망에 이르는 환자들과 비타민D의 상관관계 연구, 다양한 나라들에서 시행된 비타민D 치료의 임상결과들을 통해, 비타민D 보충 기반의 면역조절의 전략이 유리할 수 있음을 알 수 있었다. 전세계 현대인들의 비타민D 결핍은 최근 50년 간 지속적으로 증가하고 있으며, 자외선 노출로 합성할 수 있는 비타민D의 양이 충분하지 않은 부분을 식품 또는 보충제의 형태로 섭취하는 것이 여러 자가면역질환과 알레르기, 감염성 질병을 예방하는데 도움이 될 것이다.

• BMB Reports
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• 제49권2호
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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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• 제14권2호
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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.

• 한국독성학회:학술대회논문집
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• 한국독성학회 2002년도 Molecular and Cellular Response to Toxic Substances
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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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• 제33권3호
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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.

• 한국발생생물학회지:발생과생식
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• 제19권1호
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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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• 제21권1호
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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.