• Environmental Analysis Health and Toxicology
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• 제20권1호
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• pp.75-85
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• 2005

This study was aimed to know the effect of cadmium chloride (CdCl₂) on glucose transport in L6 myotube and its action mechanism. CdCl₂ increased the 2-deoxy- (l-3H)-D-glucose (2-DOG) uptake 1.9 and 2.4 fold at 10 and 25 μM respectively. To investigate the stimulating-mechanism of glucose transport induced by CdCl₂, the wortmannin and PD98059 were used as PI3K (phosphatidylinositol 3-kinase) inhibitor and MAPK inhibitor respectively, which did not affect 2-DOG uptake. This fact suggests that CdCl₂ induced 2-DOG uptake may not be concerned to the insulin signalling pathway. Whereas nifedipine, a calcium channel blocker, and trifluoperazine, a calmodulin inhibitor, were found to inhibit the 2-DOG uptake stimulted by CdCl₂. In addition, we also measured the ROS (reactive oxygen species) production and GSH level in L6 myotube to investigate the correlation between the glucose uptake and ROS. CdCl₂(25 μM) increased ROS generation approximately 1.5 fold and changed the cellular GSH level, but GSSG/GSH ratio remained unchanged. CdCl₂ stimulated 2-DOG uptake and ROS generation were inhibited by N-acetylcystein. And BSO pretreatment, a potent inhibitor of γ-GCS, resulted in the dramatic decrease of 2-DOG uptake and also the increase of the sensitivity to cadmium cytotoxicity. The obtained results suggest that CdCl₂-stimulated glucose uptake might be based on the activation of HMP shunt as an antioxidant defense mechanism of the cells.

• Journal of Pharmaceutical Investigation
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• 제28권1호
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• pp.25-33
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• 1998

Intestinal absorption of ${\beta}-lactam$ antibiotics and angiotensin converting enzyme(ACE) inhibitors has been shown to use the carrier-mediated transport system. In vitro experiments have established that the efficacy of uptake by enterocytes depends on an inwardly directed proton gradient. It was suggested that benazepril was mediated by tripeptide transport system and that amoxicillin was transported by dipeptide transport carrier. The aim of this study is to assess the influence of amoxicillin on the intestinal absorption of benazepril using in vitro diffusion chamber and in situ single pass perfusion technique in the rat in order to elucidate whether the above transport systems are competitive or not. We obtained the gastrointestinal pemeability coefficient of amoxicillin, benazepril and both of them using in vitro diffusion chamber. And also the gastrointestinal absorption clearance of amoxicillin, benazepril and both of them using in situ single-pass perfusion method at steady state were calculated. Amoxicillin and benazepril were analyzed by HPLC. The results by the use of diffusion chamber in vitro indicated that the apparent intestinal permeability coefficient of benazepril was significantly(p<0.01) decreased by amoxicillin(45.2%) and vice versa significantly(p<0.01) decreased(89.1%). The results by the in situ gastrointestinal single-pass perfusion method indicated that the intestinal absorption clearance of benazepril was significantly(p<0.05) decreased by amoxicillin (40.2%) and vice versa significantly(p<0.05) decreased(54.8%). These results might suggest that they share the same peptide carrier pathway for oral absorption.

• Toxicological Research
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• 제13권1_2호
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• pp.49-54
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• 1997

PCBs are classified as B2 (Probable human carcinogen) based on the induction of hepatocellular carcinomas in rats and mice from IRIS (Integrated Risk Information System). About 20 years ago, PCBs were phased out for electrical use in Korea, but PCBs were continuously used in the other field. Lately, there has been increasing concern on possible effects of contaminated soil to the other environment and human health. The purpose of this study is to determine PCBs level in soil at some site and to assess the human exposure doses according to exposure routes for people living within sites which expected to be exposed to PCBs. Pollution level of PCBs on the site was monitored using gas liquid chromatography. To assess the transport of PCBs in soil to plant and to air, various transfer factors(diffusion coefficient, bioconcentration factor etc.) were considered in simple calculations. To calculate the residential exposure doses by routes, some equations were considered using assumption value, which define inhalation, ingestion (soil, plant) and derreal uptake pathway. Computated results will be used as risk assessment information for human health evaluation on contaminated soil.

• Journal of Radiation Protection and Research
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• 제29권1호
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• pp.41-48
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• 2004

A safety assessment code, called SAGE (Safety Assessment Groundwater Evaluation), has been developed to describe post-closure radionuclide releases and potential radiological doses for low- and intermediate-level radioactive waste (LILW) disposal in an engineered vault facility in Korea. The conceptual model implemented in the code is focused on the release of radionuclide from a gradually degrading engineered barrier system to an underlying unsaturated zone, thence to a saturated groundwater zone. The radionuclide transport equations are solved by spatially discretizing the disposal system into a series of compartments. Mass transfer between compartments is by diffusion/dispersion and advection. In all compartments, radionuclides ate decayed either as a single-member chain or as multi-member chains. The biosphere is represented as a set of steady-state, radionuclide-specific pathway dose conversion factors that are multiplied by the appropriate release rate from the far field for each pathway. The code has the capability to treat input parameters either deterministically or probabilistically. Parameter input is achieved through a user-friendly Graphical User Interface. An application is presented, which is compared against safety assessment results from the other computer codes, to benchmark the reliability of system-level conceptual modeling of the code.

• 대한한의학방제학회지
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• 제28권1호
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• pp.81-90
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• 2020

Objectives : This study was conducted to investigate the effects of major constituents of Epimedium koreanum Nakai (Icariin, epimedium A, epimedium B, and epimedium C) on melanin synthesis. Methods : We measured melanin contents, tyrosinase activity, and expression of Rab27a in B16F10 cells cultured with Epimedium koreanum Nakai ethanol extract (EKN) and their major constituents. After treatment with H89 and dibutyryl cAMP, which inhibit or promote the activation of PKA, we observed changes in melanin synthesis and tyrosinase activity stimulated by EKN. Results : Among them, EKN and icariin enhanced tyrosinase activity and melanin contents. We confirmed that EKN augmented melanin synthesis via cAMP/PKA pathway. Icariin-induced tyrosinase activity and melanin content were attenuated by PKA inhibitor H89, while melanogenic effect of icariin was further augmented by cAMP analog, dbc AMP. However, icariin did not affect the expression of small GTPase Rab27a involved in melanosome transport. Conclusions : These results suggest that icariin promotes melanogenesis through cAMP/PKA pathway but does not affect small GTPase Rab27a.

• The Korean Journal of Physiology and Pharmacology
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• 제4권6호
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• pp.487-496
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• 2000

Insulin stimulates glucose transport in muscle and fat cells by promoting the translocation of glucose transporter (GLUT4) to the cell surface. Phosphatidylinositide 3-kinase (PI3-kinase) has been implicated in this process. However, the involvement of protein kinase B (PKB)/Akt and $PKC-{\zeta}$, those are known as the downstream target of PI3-kinase in regulation of GLUT4 translocation, is not known yet. An interesting possibility is that these protein kinases phosphorylate GLUT4 directly in this process. In the present study, $PKB-{\alpha}$ and $PKC-{\zeta}$ were added exogenously to GLUT4-containing vesicles purified from low density microsome (LDM) of the rat adipocytes by immunoadsorption and immunoprecipitation for direct phosphorylation of GLUT4. Interestingly GLUT4 was phosphorylated by $PKC-{\zeta}$ and its phosphorylation was increased in insulin stimulated state but GLUT4 was not phosphorylated by $PKB-{\alpha}.$ However, the GST-fusion proteins, GLUT4 C-terminal cytoplasmic domain (GLUT4C) and the entire major GLUT4 cytoplasmic domain corresponding to N-terminus, central loop and C-terminus in tandem (GLUT4NLC) were phosphorylated by both $PKB-{\alpha}$ and $PKC-{\zeta}.$ The immunoblots of $PKC-{\zeta}$ and $PKB-{\alpha}$ antibodies with GLUT4-containing vesicles preparation showed that $PKC-{\zeta}$ was co-localized with the vesicles but not $PKB-{\alpha}.$ From the above results, it is clear that $PKC-{\zeta}$ interacts with GLUT4-containing vesicles and it phosphorylates GLUT4 protein directly but $PKB-{\alpha}$ does not interact with GLUT4, suggesting that insulin-elicited signals that pass through PI3-kinase subsequently diverge into two independent pathways, an Akt pathway and a $PKC-{\zeta}$ pathway, and that later pathway contributes, at least in part, insulin stimulation of GLUT4 translocation in adipocytes via a direct GLUT4 phosphorylation.

• 한국가금학회지
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• 제37권3호
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• pp.275-282
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• 2010

닭의 대사 생리에 대한 연구는 산업적 가치 및 생물학, 의학적으로도 매우 중요하다. 닭의 유전체 염기서열 분석 결과는 2004년에 처음 발표되었고, 이러한 유전체 정보를 바탕으로 유전형과 표현형의 상관관계를 분석하는 연구가 필요하다. 따라서 본 연구는 닭 유전체 정보를 바탕으로 대사 경로를 재확립하고, 닭 특이 대사 경로 유전체 데이터베이스를 구축하였다. 이를 위해 Perl 언어를 기반으로 개발된 자동 파이프라인(pipeline)을 이용하여 여러 생물정보 데이터베이스에 산재해 있는 닭 유전체에 관한 정보를 통합한 닭 특이 통합 데이터베이스를 구축하였다. 또한, 구축된 닭 특이 통합 데이터베이스를기반으로PathoLogic 알고리즘을구현한Pathway Tools 소프트웨어를 이용하여 닭 특이 대사 경로를 재확립하였다. 결과적으로, 닭 유전체 Gallus_gallus-2.1에서 2,709개의 효소, 71개의 운반체(transporter)와 1,698개의 효소 반응, 8개의 운반 반응(transport reaction)이 도출되었다. 이를 통해 총 212개의 대사 경로가 재확립되었고, 1,360개의 화합물(compound)이 닭 특이 대사 데이터베이스에 포함되었다. 다른 종(사람, 생쥐, 소)과의 비교 분석을 통해 중요한 대사 경로가 닭 유전체에 보존되어 있음을 보였다. 또한, 닭 유전체의 assembly와 annotation의 질을 높이는 노력과 닭 및 조류에서 유전자 기능 및 대사 경로에 대한 연구가 필요한 것으로 나타났다. 결론적으로, 본 연구에서 재확립된 닭의 대사 경로 및 데이터베이스는 닭 및 조류의 대사 연구뿐만 아니라 포유동물 및 미생물과의 비교 생물학적 접근을 통한 의학 및 생물학적 연구에 활용될 것으로 기대된다.

• 생명과학회지
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• 제24권2호
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• pp.196-208
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• 2014

식물의 생활사 동안 물부족 스트레스는 식물의 생장과 발달에 해로운 영향을 끼치는 대표적인 스트레스이다. 유용 작물의 생산성을 증가시키기 위하여, 물부족 스트레스를 극복하는 일은 식물학 연구 분야에서 가장 중요한 이슈로 대두되어 왔다. 식물의 호르몬 중에서 앱시스산은 물부족 스트레스에 대해 식물이 저항성을 나타내는데 가장 중요한 호르몬으로서 역할을 수행하며, 씨앗의 발아, 기공의 개폐, 유묘의 성장과 같은 다양한 발달 과정에도 관여하고 있다. 그러므로, 앱시스산에 의해 매개되는 식물의 신호전달 기작을 명확히 이해하는 것은 물부족 스트레스에 대한 내성을 갖는 유용 식물을 생산해내기 위해 가장 효과적인 방법이 될 것이다. 한편, 인산화, 유비퀴틴화와 같은 번역 후 변형 과정은 식물이 다양한 환경적 스트레스 하에서 신속하게 적응을 하기 위해 가장 효율적인 기작으로 인식되어 왔는데, 이는 전사수준에서의 조절과 달리 이미 존재하는 신호전달 물질의 활성과 안정성을 직접적으로 빠르게 조절할 수 있기 때문이다. 본 총설에서는 앱시스산의 신호전달 과정과 관련된 최근 연구 동향을 업데이트하고자 하며, 특히 이러한 신호전달 과정을 앱시스산 수송, 인식, 신호전달 및 번역 후 변형 과정에 초점을 맞추어 알아보고자 한다. 또한 그러한 조절 기작이 농업분야에서 유용 작물을 생산하는데 어떻게 적용될 수 있는지에 대한 향후 전망에 대해서도 기술하고자 한다.

• BMB Reports
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• 제45권8호
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• pp.427-432
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• 2012

Primary cilia, single hair-like appendage on the surface of the most mammalian cells, were once considered to be vestigial cellular organelles for a past century because of their tiny structure and unknown function. Although they lack ancestral motility function of cilia or flagella, they share common ground with multiciliated motile cilia and flagella on internal structure such as microtubule based nine outer doublets nucleated from the base of mother centrioles called basal body. Making cilia, ciliogenesis, in cells depends on the cell cycle stage due to reuse of centrioles for cell division forming mitotic spindle pole (M phase) and assembling cilia from basal body (starting G1 phase and maintaining most of interphase). Ciliary assembly required two conflicting processes such as assembly and disassembly and balance between these two processes determines the length of cilia. Both process required highly conserved transport system to supply needed substance to grow tip of cilia and bring ciliary turnover product back to the base of cilia using motor protein, kinesin and dynein, and transport protein complex, IFT particles. Disruption of ciliary structure or function causes multiple human disorder called ciliopathies affecting disease of diverse ciliated tissues ranging from eye, kidney, respiratory tract and brain. Recent explosion of research on the primary cilia and their involvement on animal development and disease attracts scientific interest on how extensively the function of cilia related to specific cell physiology and signaling pathway. In this review, I introduce general features of primary cilia and recent progress in understanding of the ciliary length control and signaling pathways transduced through primary cilia in vertebrates.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.239.1-239.1
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• 2011

Dye sensitized solar cells (DSC) are promising devices for inexpensive, nontoxic, transparent, and large-scale solar energy conversion. Generally thick $TiO_2$ nanoporous films act as efficient photoanodes with their large surface area for absorbing light. However, electron transport through nanoparticle networks causes the slowdown and the loss of electron transport because of a number of interparticle boundaries inside the conduction path. We have studied DSCs with precisely dimension-controlled $TiO_2$ nanotubes array as photoanode. $TiO_2$ nanotubes array is prepared by template-directed fabrication method with atomic layer deposition. Well-ordered nanotubes array provides not only large surface area for light absorbing but also direct pathway for electrons with minimalized grain boundaries. Large enlongated anatase grains in the nanotubes could enhance the conductivity of electrons, but also suppress the recombination with holes through defect sites during diffusion into the electrode. To study the effect of grain boundaries, we fabricated two kinds of nanotubes which have different grain sizes by controlling deposition conditions. And we studied electron conduction through two kinds of nanotubes with different grain structures. The solar cell performance was studied as a function of thickness and grain structures. And overall solar-to-electric energy conversion efficiencies of up to 7% were obtained.