• 한국수소및신에너지학회논문집
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• 제34권6호
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• pp.673-681
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• 2023

Hydrocarbon-based polymer membranes to replace perfluorinated polymer membranes are being continuously researched. However, hydrocarbon-based membranes have a problem in that they are less durable than fluorine-based membranes. In this study, we sought to compare the annealing effect to improve the durability of sulfonated poly(ether ether ketone) (SPEEK). After membranes formation, thermogravimetric analysis and tensile strength were measured to compare changes in membranes properties due to annealing. After manufacturing the membrane and electrode assembly (MEA), the initial performance and chemical durability was compared with unit cell operation. During the 24-hour annealing process, the strength increased due to the increase in-S-O-S-crosslinking, and the sulfonic acid group decreased, leading to a decrease in I-V performance. By annealing, the hydrogen permeability was reduced to less than 1/10 of that of the nafion membrane, and as a result, open circuit voltage (OCV) and durability was improved. The SPEEK membranes annealed for 24 hours showed higher durability than the nafion 211 membranes of the same thickness.

• Biomolecules & Therapeutics
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• 제32권1호
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• pp.162-169
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• 2024

Particulate matter (PM) constitutes a hazardous blend of organic and inorganic particles that poses health risks. Inhalation of fine airborne PM with a diameter of ≤ 2.5 ㎛ (PM_2.5) can lead to significant lung impairments. (+)-afzelechin (AZC), a natural compound sourced from Bergenia ligulata, boasts a range of attributes, including antioxidant, antimicrobial, anticancer, and cardiovascular effects. However, knowledge about the therapeutic potential of AZC for patients with PM_2.5-induced lung injuries remains limited. Thus, in this study, we investigated the protective attributes of AZC against lung damage caused by PM_2.5 exposure. AZC was administered to the mice 30 min after intratracheal instillation of PM_2.5. Various parameters, such as changes in lung tissue wet/dry (W/D) weight ratio, total protein/total cell ratio, lymphocyte counts, levels of inflammatory cytokines in bronchoalveolar lavage fluid (BALF), vascular permeability, and histology, were evaluated in mice exposed to PM_2.5. Data demonstrated that AZC mitigated lung damage, reduced W/D weight ratio, and curbed hyperpermeability induced by PM_2.5 exposure. Furthermore, AZC effectively lowered plasma levels of inflammatory cytokines produced by PM_2.5 exposure. It reduced the total protein concentration in BALF and successfully alleviated PM_2.5-induced lymphocytosis. Additionally, AZC substantially diminished the expression levels of Toll-like receptors 4 (TLR4), MyD88, and autophagy-related proteins LC3 II and Beclin 1. In contrast, it elevated the protein phosphorylation of the mammalian target of rapamycin (mTOR). Consequently, the anti-inflammatory attribute of AZC positions it as a promising therapeutic agent for mitigating PM_2.5-induced lung injuries by modulating the TLR4-MyD88 and mTOR-autophagy pathways.

• The Korean Journal of Physiology
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• 제18권1호
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• pp.19-35
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• 1984

Since the first report of Drury and $Szent-Gy{\ddot{o}}rgyi$ in 1929, the inhibitory influences of adenosine on the heart have repeatedly been described by many investigators. These studies have shown that adenosine and adenine nucleotides have overall depressant effects, similar to those of acetylcholine. Heart beats become slow and weak. It is also well known that adenosine is a potent endogenous coronary vasodilator. Many investigations on the working mechanisms of adenosine have been focused mainly on the effects of the coronary blood flow. However, the cellular mechanisms underlying the inhibitory action of adenosine on sinus node are not well understood yet. Thus, this study was undertaken to examine the behavior of rabbit SA node under influence of adenosine. In these series of experiments three kinds of preparations were used: whole atrial pair, left atrial strip, and isolated SA node preparations. The electrical activity of SA node was recorded with conventional glass microelectrodes 30 to 50 $M{\Omega}$. The preparations were superfused with bicarbonate-buffered Tyrode solution of pH 7.35 and aerated with a gas mixture of $3%\;CO_2-97%\;O_2$ at $35^{\circ}C$. In whole atrial pair, adenosine suppressed sinoatrial rhythm in a dose-dependent manner. Effect of adenosine on atrial rate appeared at the concentration of $10^{-5}M$ and was enhanced in parallel with the increase in adenosine concentration. Inhibitory action of adenosine on pacemaker activity was more prominent in the preparation pretreated with norepinephrine, which can steepen the slope of pacemaker potential by increasing permeability of $Ca^{+2}$. Calcium ions in perfusate slowly produced a marked change in sinoatrial rhythm. Elevation of the calcium concentration from 0.3 to 8 mM increased the atrial rate from 132 to 174 beats/min, but over 10 mM $Ca^{+2}$ decreased. The inhibitory effect of adenosine on sinoatrial rhythm developed very rapidly. Atrial rate was recovered promptly from the adenosine-induced suppression by the addition of norepinephrine, but extra $Ca^{+2}$ was less suitable to restore the suppression of atrial rate. Adenosine suppressed also atrial contractility in the same dosage range that restricted pacemaker activity, even in the reserpinized preparation. In isolated SA node preparation, spontaneous firing rate of SA node at $35^{\circ}C$(mean{\pm}SEM, n=16) was $154{\pm}3.3\;beats/min. The parameters of action potentials were: maximum diastolic potential(MDP), $-73{\pm}1.7\;mV: overshoot(OS), $9{\pm}1.4\;mV: slope of pacemaker potential(SPP), $94{\pm}3.0\;mV/sec. Adenosine suppressed the firing rate of SA node in a dose-dependent manner. This inhibitory effect appeared at the concentration of $10^{-6}M$ and was in parallel with the increase in adenosine concentration. Changes in action potential by adenosine were dose-dependent increase of MDP and decrease of SPP until $10^{-4}M$. Above this concentration, however, the amplitude of action potential decreased markedly due to the simultaneous decrease of both MDP and OS. All these effects of adenosine were not affected by pretreatment of atropine and propranolol. Lowering extra $Ca^{2+}$ irom 2 mM to 0.3 mM resulted in a marked decrease of OS and SPP, but almost no change of MDP. However, increase of perfusate $Ca^{2+}$ from 2 mM to 6 or 8 mM produced a prominent decrease of MDP and a slight increase of OS and SPP. Dipyridamole(DPM), which is known to block the adenosine transport across the cell membrane, definately potentiated the action of adenosine. The results of this experiment suggest that adenosine suppressed pacemaker activity and atrial contractility simultaneously and directly, by decreasing $Ca^{2+}-permeability$ of nodal and atrial cell membranes.

• 한국응용과학기술학회지
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• 제41권1호
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• pp.9-18
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• 2024

토복령은 우수한 항균, 항산화, 항염증 효능을 가진 소재로 알려져 있다. 이러한 토복령(Smilax china)의 추출물의 기능성을 화장품에 적용하기 위한 기초연구로써 토복령에서 발견되는 플라보노이드인 quercetin, catechin, naringenin의 농도별 경피 투과 특성을 조사할 필요성이 있다. Marzulli의 정의에 적용한 결과 케르세틴의 Kp 값은 0.1 mg/mL에서 "빠름"으로 분류되었고, 0.2 및 0.4 mg/mL에서 "보통"으로 분류되었다. 특히, 농도가 증가함에 따라 투과 속도가 감소하는 경향이 있었다. 나린제닌의 경우 Flux 값은 각각 0.1, 0.2 및 0.4 mg/mL 농도에서 0.69, 1.07 및 1.42 ㎍/hr/cm²이었으며, 해당 Kp 값은 각각 6.95, 5.34 및 3.56이었다. 나린제닌의 Kp 값은 모든 농도에서 "보통" 범주에 속하며, 케르세틴과 관찰된 것과 같이 농도가 높아짐에 따라 투과 속도가 감소하였다. 카테킨의 경우 Flux 값은 각각 0.1, 0.2 및 0.4 mg/mL 농도에서 0.75, 1.09 및 1.66 ㎍/hr/cm²이었으며, 해당 Kp 값은 각각 7.55, 5.46 및 4.16이었다. 카테킨의 Kp 값은 모든 농도에서 일관되게 "보통"으로 분류되었다. 여드름 저해능 및 항염증 효능이 우수한 토복령 추출물의 유효성분인 quercetin, catechin, naringenin의 경피 투과 특성이 보통 이상으로 나타나 기능성 화장품에 사용할 수 있는 우수한 천연물 소재인 것을 확인할 수 있었다.

• Journal of Korean Neurosurgical Society
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• 제30권6호
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• pp.683-687
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• 2001

Objective : Angiogenesis, the proliferation of capillary endothelial cells, is a vital component in the development, progression, and metastasis of many human tumors. Vascular endothelial growth factor(VEGF) is an endothelial cell-specific mitogen and induces angiogenesis and vascular permeability. The features of glioblastoma, distinct from low grade astrocytomas, are the presence of necroses and vascular endothelial proliferation. In this study, we investigated VEGF expression in the different grades of astrocytomas and determined whether VEGF expression correlates with development of glioblastoma and progression of astrocytomas. Patients and Methods : Forty seven patients with astrocytic tumors(24 males and 23 females), aged 3 to 65 years, were evaluated. Immunohistochemical staining was carried out using labelled streptavidin biotin method and primary antibody was a antirabbit polyclonal Ab against N-terminus region of VEGF165(Oncogene research product, MA, USA). Immunoreactivity(IR) was classified into no IR(absent or a trace of stain), moderate IR and intense IR by level of staining amount and intensity. Results : Six pilocytic astrocytomas showed 3 no IR and 3 moderate IR, 10 astrocytomas showed 2 no IR, 6 moderate IR and 2 intense IR, 12 anaplastic astrocytomas showed I no IR, 7 moderate IR and 4 intense IR and 19 glioblastomas showed 1 no IR, 11 moderate IR and 7 intense IR. Immunoreactivity was significantly different between low and high grade of tumors but there was no significant difference between anaplastic astrocytomas and glioblastomas. Gemistocytic tumor cells represented the predominent VEGF-immunoreactive cell types, as compared with compactly-arranged small tumor cells. In glioblastomas VEGF IR was observed in both perinecrotic and vital tumor areas. Conclusion : VEGF seems to be a important angiogenic factor in anaplastic astrocytomas and glioblastomas and VEGF expression may contribute to neovascularization of human astrocytomas.

• 한국지반환경공학회 논문집
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• 제9권6호
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• pp.31-41
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• 2008

본 연구에서는 해성점토로 기 매립된 준설토 지반의 압밀특성 및 평가방법에 대한 연구를 실시하였다. 자중압밀 진행 중인 고함수비의 준설매립지반은 불교란 시료의 채취가 사실상 불가능하므로 압밀특성 파악에 어려움이 있다. 이를 위해 실무에서 압밀거동 분석을 위해 적용하는 압밀정수를 교란된 시료로 이용하여 실내실험으로 평가하는 방법에 대하여 연구를 진행하였다. 실험은 기본물성실험과 표준압밀실험, 일정변형률압밀실험과 60, 100, 150mm 직경의 Rowe-cell압밀실험을 수행하였으며, 함수비 조건을 변화하면서 40g의 중력수준에서 원심모형실험을 수행하였다. 실내 압밀실험시 현장의 응력조건에 해당하는 강제압밀로 시료를 조성하여 보다 합리적인 압밀특성을 파악할 수 있었다. 원심모형실험결과로 획득한 시간-침하관계를 침하예측기법으로 분석하여 최종침하량을 분석하였다. 분석결과, Asaoka방법을 적용한 해석결과가 원심모형실험에 의한 자중압밀결과의 경향을 잘 나타내었으며, 이를 통하여 최종침하량을 추정하였다. 또한, 실내압밀실험과 자중압밀실험결과에 대한 역해석을 통하여 유한변형률 압밀이론의 간극비-유효응력-투수계수 구성관계식을 산정하였다. 구성관계와 다양한 압밀실험을 통하여 획득한 결과를 비교 분석하여 연구대상 지역의 압축지수, 팽창지수, 체적변화계수, 연직 및 수평압밀계수 등의 압밀정수를 제안하였다.

• 대한기계학회논문집B
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• 제36권10호
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• pp.979-988
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• 2012

연료전지 GDL 내의 물질전달에 관한 연구를 위하여 실제 GDL 을 고해상도 3 차원 스캐닝 장비를 활용하여 GDL의 다공 구조를 실측하였다. 측정된 Data의 노이즈를 제거하고 GDL의 Carbon-fiber 구조를 전산해석이 가능한 모델로 자동적으로 형성하는 알고리즘을 개발하였으며, 이 모델을 활용하여 스택 체결 시 압축에 의한 GDL 구조 변형을 예측하고, Carbon-fiber의 정렬 방향에 따른 변형 특성을 파악하였다. 또한, CFD 기법 중 하나인 VOF 모델과 Pore-network 모델을 이용하여 GDL 내부의 물거동 및 반응기체의 물질거동을 예측하였다. 마지막으로 상사실험을 통하여 해석 결과에 대한 검증을 실시하였다. 이를 통하여 실제 체결에 의하여 압축 변형된 GDL 내에서의 물질거동을 좀 더 정확히 예측할 수 있는 방법을 마련하고, GDL 체결 방향 및 최적 MPL 두께 선정 등의 실제 설계에 활용할 수 있었다.

• 생명과학회지
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• 제17권9호통권89호
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• pp.1298-1302
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• 2007

${\beta}-lapachone$은 남미지역에서 자생하는 Tabebuia avellanedae라는 나무의 수피에서 동정된 quinone계 물질로서 다양한 인체암세포에서 항암효과가 있는 것으로 알려져있다. 본 연구에서는 ${\beta}-lapachone$의 암 전이 억제에 대한 연구의 일환으로 HepG2 및 Hep3B 인체 간암 세포의 전이관련 유전자의 발현에 미치는 ${\beta}-lapachone$의 영향을 조사하였다. MTT assay 및 세포형태변화 관찰 결과에서 ${\beta}-lapachone$ 처리에 따라 HepG2와 Hep3B 세포들은 ${\beta}-lapachone$ 농도 의존적으로 세포의 증식이 억제되었으며 그 형태적 변형도 동반하였다. ${\beta}-lapachone$처리에 의한 암 전이 지표가 되는 IGF-lR, Tjs (ZO-1, claudin-3,-4) 및 Tj 조절인자(${\beta}-catenin$)의 발현을 RT-PCR과 Western blot analysis를 통하여 확인한 결과 ${\beta}-lapachone$ 처리가 IGF-1R의 발현 억제와 Tj 유전자 발현의 증가를 유도함으로써 ${\beta}-lapachone$이 Tj를 강화하여 암세포의 전이 억제작용을 하는 것으로 관찰 되었다. 이상의 결과는 인체 간암세포에서 ${\beta}-lapachone$의 항전이 작용의 이해에 중요한 기초 자료가 될 것으로 생각한다.

• Tuberculosis and Respiratory Diseases
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• 제78권3호
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• pp.218-226
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• 2015

Background: Eph receptors and ephrin ligands have several functions including angiogenesis, cell migration, axon guidance, fluid homeostasis, oncogenesis, inflammation and injury repair. The EphA2 receptor potentially mediates the regulation of vascular permeability and inflammation in response to lung injury. Methods: Mice were divided into 3 experimental groups to study the role of EphA2 signaling in the lipopolysaccharide (LPS)-induced lung injury model i.e., IgG+phosphate-buffered saline (PBS) group (IgG instillation before PBS exposure), IgG+LPS group (IgG instillation before LPS exposure) and EphA2 monoclonal antibody (mAb)+LPS group (EphA2 mAb pretreatment before LPS exposure). Results: EphA2 and ephrinA1 were upregulated in LPS-induced lung injury. The lung injury score of the EphA2 mAb+LPS group was lower than that of the IgG+LPS group ($4.30{\pm}2.93$ vs. $11.45{\pm}1.20$, respectively; p=0.004). Cell counts (EphA2 mAb+LPS: $11.33{\times}10^4{\pm}8.84{\times}10^4$ vs. IgG+LPS: $208.0{\times}10^4{\pm}122.6{\times}10^4$; p=0.018) and total protein concentrations (EphA2 mAb+LPS: $0.52{\pm}0.41mg/mL$ vs. IgG+LPS: $1.38{\pm}1.08mg/mL$; p=0.192) were decreased in EphA2 mAb+LPS group, as compared to the IgG+LPS group. In addition, EphA2 antagonism reduced the expression of phospho-p85, phosphoinositide 3-kinase $110{\gamma}$, phospho-Akt, nuclear factor ${\kappa}B$, and proinflammatory cytokines. Conclusion: This results of the study indicated a role for EphA2-ephrinA1 signaling in the pathogenesis of LPS-induced lung injury. Furthermore, EphA2 antagonism inhibits the phosphoinositide 3-kinase-Akt pathway and attenuates inflammation.

• 대한한방내과학회지
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• 제25권3호
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• pp.461-472
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• 2004

Objectives : For the screening of neuroprotective effects of medicinal herbs, the complex system of animal models suffer some disadvantages in controlling critical parameters such as blood pressure and body temperature. Additionally, application of drugs to the appropriate brain area sometimes is difficult, due to poor permeability though the blood brain barrier, and so potential protective effects might be masked. Methods : Organotypic hippocampal slice culture (OHSC) method has the advantages of being relatively easy to prepare and of maintaining the general structure, including tissue integrity and the connections between cells. Drugs can easily be applied and neuronal damage can easily be quantified by using tissues and culture media. This study demonstrates neuroprotective effects of Puerariae radix (葛根, PR), Salviae miltiorrhizae radix (丹蔘, SR), Rhei rhizoma (大黃, RR), and Bupleuri radix (柴胡, BR). These were screenedand compared to MK-801, antagonist of NMDA receptors, by using OHSC of 1 week-old Sprague-Dawley rats. Oxygen/glucose deprivation (OGD) were conducted in an anaerobic chamber $(85%\;N_2,\;10%\;CO_2\;and\;5%\;H_2)$ in a deoxygenated glucose-free medium for 60 minutes. Water extracts of each herbs were treated to culture media with $5\;{\mu}g/ml$ for 48 hours. Results : Neuronal cell death in the cultures was monitored by densitometric measurements of the cellular uptake of propidium iodide (PI). PI fluorescence images were obtained at 48 hours after the OGD and medicinal herb treatment. Also TUNEL-positive cells in the CAI and DG regions and LDH concentrations in culture media were measured at 48 hours after the OGD. According to measured data, MK-801, PR, SR and BR demonstrated significant neuroprotective effect against excessive neuronal cell death and apoptosis induced by the OGD insult. Especially, PR revealed similar neuroprotective effect to MK-801 and RR demonstrated weak neuroprotective effect. Conclusions : These results suggest that OHSC can be a suitable method for screening of neuroprotective effects of medicinal herbs. (This work was supported by the research program of Dongguk University and Grant 01-PJ9-PG1-01CO03-0003 from Ministry of Health & Welfare.)