• Natural Product Sciences
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• 제9권3호
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• pp.161-166
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• 2003

In the course of our studies for new anticancer medicinal plants, we evaluated the effects of an alcohol-water (1:1, V/V) extract of Dendrostellera lesserii (Thymelaeaceae) leaves on the growth rates of breast tumors of rats. The breast tumors were induced in a group of rats by Dimethylbenz[a]anthracene (DMBA) injection. Our data showed that daily oral feeding of the crude extract to the rats, for 20 consecutive weeks, significantly repressed the growth rates of the breast tumors. In addition, the probable effect of D. lessertii crude extract or one of its purified active components on metastasis was evaluated using wehi-164 cells. Treatment of the cells with a single nontoxic dose of the purified active component for 48 hours inhibited the adhesion of the cells to the immobilized fibronectin molecules by almost 80% compared to the untreated control cells.

• Journal of the Optical Society of Korea
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• 제13권1호
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• pp.86-91
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• 2009

The electrons injected into a laser wakefield undergo betatron oscillation and give rise to the emission of intense X-ray radiation. To investigate the generation conditions of the X-rays, the relativistic motion of an electron injected in an off-axis position has been simulated with wakefield profiles which are pre-calculated with a two-dimensional particle-in-cell code. The wakefield with a plasma density of $1.78{\times}10^{18}\;cm^{-3}$ is generated by the laser with an intensity of $1.37{\times}10^{18}\;W/cm^2$ and a pulse width of 30 fs. From the calculation of the single particle motion, the characteristics of the betatron radiation are investigated in the time domain. As the transverse injection position increases, the power and the duration time of the radiation increase, but the width of each pulse decreases.

• Natural Product Sciences
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• 제15권4호
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• pp.222-228
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• 2009

Lupus is characterized by immunoregulatory abnormalities between T- and B-cells leading to autoantibody production and multiorgan injuries. We investigated whether bamboo culm extract (BC) ameliorates aberrant activation of T cells and B cells and attenuate production of IL-6 in pristane-induced lupus mice. Lupus was induced by i.p. a single injection of 0.5 ml of pristane in female BALB/c mice, which, later about 4 months, were used as a lupus model. The pristane-induced lupus mice and healthy mice were injected i.p. with BC 5 ${\mu}l$/kg or PBS once a day for 3 weeks. These results demonstrated that BC significantly decreased levels of serum and BAL IL-6 and production of IL-6 by macrophages with/without LPS, and downregulated expression of NKT cell and CD86+ CD45R/B220+, but not CD80+CD45R/B220+ and CD69+CD4+ in the splenocytes in pristaneinduced lupus mice. Moreover, BC greatly increased Con A-stimulated production of IL-6, IL-10 and IFN-${\gamma}$ by splenocytes obtained from pristane-induced lupus mice. Therefore, our findings suggest that BC may ameliorate lupus pathogenesis in pristane-induced lupus mice via downregulation of aberrant activation of NKT cells and B cells and inhibition of production of IL-6.

• Animal cells and systems
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• 제13권4호
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• pp.357-362
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• 2009

Hesperidin, the most abundant polyphenolic compound found in citrus fruits, has been known to possess neuroprotective, sedative, and anticonvulsive effects on the nervous system. In a recent electrophysiological study, it was reported that hesperidin induced biphasic change in population spike amplitude in hippocampal CA1 neurons in response to both single spike stimuli and theta-burst stimulation depending on its concentration. However, the precise mechanism by which hesperidin acts on neuronal functions has not been fully elucidated. Here, using whole-cell patch-clamp recording, we revealed that hesperidin did not affect excitatory synaptic activities such as basal synaptic transmission and theta-burst LTP. Moreover, in a current injection experiment, spike number, resting membrane potential and action potential threshold also remained unchanged. Taken together, these results indicate that the effects of hesperidin on the neuronal functions such as spiking activity might not be attributable to either modification of excitatory synaptic transmissions or changes in membrane excitability in hippocampal CA1 neuron.

• Archives of Pharmacal Research
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• 제29권8호
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• pp.651-656
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• 2006

This study examined the chemopreventive effect of saponins that were isolated from the roots of Platycodon grandiflorum A. DC (Campanulaceae), Changkil saponins (CKS), against the tobacco-specific carcinogen, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), -on lung tumorigenesis in A/J mice. The mice were treated with a single NNK dose (100 mg/kg b.w., i.p.). CKS (0.5, 1, 4 mg/kg body wt.) was administered orally daily for 3 days/week beginning 1 day after the NNK treatment and was maintained throughout the experiment. The administration of CKS suppressed the NNK-induced increase in the level of proliferating cell nuclear antigen, which are a marker of cell proliferation, in the lungs of the mice 4 weeks after the NNK injection. Twenty-five weeks after the NNK treatment, the mice were sacrificed and the number of surface lung tumors was measured. CKS significantly reduced the number of lung tumors induced by NNK in a dose dependent manner. These results suggest that CKS suppresses the development of lung tumors and has a chemopreventive effect against NNK-induced mouse lung tumorigenesis.

• 전력전자학회논문지
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• 제13권4호
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• pp.311-318
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• 2008

본 논문은 소프트 스위칭 기법을 적용한 싱크로너스 양방향 DC-DC 컨버터를 제안한다. 제안된 컨버터는 싱크로너스 벅 컨버터를 병렬구성을 하여 인터리브드 기법을 통해 도통 손실을 줄이고, 하나의 공진인덕터를 사용한 ZVT-Cell을 적용함으로써 스위칭 손실을 최소화 하였다. 전 부하 범위에서 CCM(Continuous Conduction Mode) 으로 동작하고 ZVS가 성립되도록 하였으며, 전류주입 기법을 통해 넓은 출력전압 범위에서도 ZVS 조건을 만족하였다. 또한, 기존 싱크로너스 벅 컨버터의 데드타임(dead time)동안 발생하는 역병렬 다이오드의 도통손실 및 dv/dt, di/dt 발생을 저감하는 효과를 얻을 수 있다. 제안된 컨버터의 유효성은 실험을 통해서 검증하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.240-240
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• 2010

A multiple alloy metal nano-dots memory using FN tunneling was investigated in order to confirm its structural possibility for future flash memory. In this work, a multiple FePt nano-dots device with a high work function (~5.2 eV) and extremely high dot density (${\sim}\;1.2{\times}10^{13}/cm^2$) was fabricated. Its structural effect for multiple layers was evaluated and compared to one with a single layer in terms of the cell characteristics and reliability. We confirm that MOS capacitor structures with 2-4 multiple FePt nano-dot layers provide a larger threshold voltage window and better retention characteristics. Furthermore, it was also revealed that several process parameters for block oxide and inter-tunnel oxide between the nano-dot layers are very important to improve the efficiency of electron injection into multiple nano-dots. From these results, it is expected that a multiple FePt nano-dots memory using Fowler-Nordheim (FN)-tunneling could be a candidate structure for future flash memory.

• 대한방사성의약품학회지
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• 제7권2호
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• pp.93-98
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• 2021

meta-iodobenzylguanidine is one of the norepinephrine analogs and reuptakes together with norepinephrine with norepinephrine transporter. The radioiodinated ligand, ¹²³I-meta-iodobenzylguanidine, is the most widely used for single photon emission computed tomography imaging to diagnose functional abnormalities and tumors of the sympathetic nervous system. In this study, we performed cellular uptake studies of ¹²³I-meta-iodobenzylguanidine in positive- and negative-norepinephrine transporter cells in vitro to verify the uptake activity for norepinephrine transporter. After ¹²³I-meta-iodobenzylguanidine was injected via a tail vein into normal mice, Single photon emission computed tomography/computed tomography images were acquired at 1 h, 4 h, and 24 h post-injection, and quantified the distribution in each organ including the adrenal medulla as a norepinephrine transporter expressing organ. In vitro cell study showed that ¹²³I-meta-iodobenzylguanidine specifically uptaked via norepinephrine transporter, and significant uptake of ¹²³I-meta-iodobenzylguanidine in the adrenal medulla in vivo single photon emission computed tomography images. These results demonstrated that single photon emission computed tomography imaging with ¹²³I-meta-iodobenzylguanidine were able to quantify the biodistribution in vivo in the adrenal medulla in normal mice.

• Childhood Kidney Diseases
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• 제22권1호
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• pp.1-6
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• 2018

Rituximab (RTX) is a chimeric monoclonal antibody that inhibits CD20-mediated B-cell proliferation and differentiation. Several studies have examined its use in intractable nephrotic syndrome (NS) with some positive results. However, those studies examined such effects for a short-term period of 1 year, and some patients continued to relapse after a lapse in RTX treatment. Our use of RTX as a maintenance therapy (RTX injection when the CD19 cell count exceeded $100-200/{\mu}L$ before relapse) showed some noticeable efficacy. We used RTX in 19 patients with steroid-dependent NS (SDNS). In 12 patients treated with RTX maintenance therapy, only one relapse occurred. The mean treatment period was $23.4{\pm}12.7months$, and the mean number of RTX administrations was $3.9{\pm}1.6$. The relapse rates were decreased (from 2.68/year to 0.04/year), and the drug-free period also increased (from 22.5 days/year to 357.1 days/year) during maintenance therapy. The other seven patients were treated with one cycle of RTX or additional cycles in case of relapse (non-maintenance therapy). Relapse rates were significantly decreased after RTX treatment (from 1.76/year to 0.96/year, P=0.017). The relapse-free period was $15.55{\pm}7.38$ (range, 5.3-30.7) months. No severe side effects of RTX were found except for a hypersensitivity reaction such as fever and chills during its infusion. In conclusion, RTX is considered an effective and safe option to reduce the relapse rate by a single- or maintenance-interval therapy in SDNS.

• Molecules and Cells
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• 제40권6호
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• pp.386-392
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• 2017

Periodontal ligament stem cells (PDLSCs) are multipotent stem cells derived from periodontium and have mesenchymal stem cell (MSC)-like characteristics. Recently, the perivascular region was recognized as the developmental origin of MSCs, which suggests the in vivo angiogenic potential of PDLSCs. In this study, we investigated whether PDLSCs could be a potential source of perivascular cells, which could contribute to in vivo angiogenesis. PDLSCs exhibited typical MSC-like characteristics such as the expression pattern of surface markers (CD29, CD44, CD73, and CD105) and differentiation potentials (osteogenic and adipogenic differentiation). Moreover, PDLSCs expressed perivascular cell markers such as NG2, ${\alpha}-smooth$ muscle actin, platelet-derived growth factor receptor ${\beta}$, and CD146. We conducted an in vivo Matrigel plug assay to confirm the in vivo angiogenic potential of PDLSCs. We could not observe significant vessel-like structures with PDLSCs alone or human umbilical vein endothelial cells (HUVECs) alone at day 7 after injection. However, when PDLSCs and HUVECs were co-injected, there were vessel-like structures containing red blood cells in the lumens, which suggested that anastomosis occurred between newly formed vessels and host circulatory system. To block the $SDF-1{\alpha}$ and CXCR4 axis between PDLSCs and HUVECs, AMD3100, a CXCR4 antagonist, was added into the Matrigel plug. After day 3 and day 7 after injection, there were no significant vessel-like structures. In conclusion, we demonstrated the perivascular characteristics of PDLSCs and their contribution to in vivo angiogenesis, which might imply potential application of PDLSCs into the neovascularization of tissue engineering and vascular diseases.