Two zinc-aminoclays' in-vitro cytotoxicity assessment in HeLa cells and in-vivo embryotoxicity assay in zebrafish

Chun, H.S.,Park, D.,Eun Lim, S.,Jeong, K.H.,Park, J.S.,Park, H.J.,Kang, S.,Kang, K.S.,Park, H.G.,An, H.R.,Huh, Y.S.,Lee, Y.C. Academic Press 2017 Ecotoxicology and environmental safety Vol.137 No.-

<P>Two zinc-aminoclays [ZnACs] with functionalized primary amines [(-CH2)(3)NH2] were prepared by a simple solgel reaction using cationic metal precursors of ZnCl2 and Zn(NO3)(2) with 3-aminopropyl triethoxysilane [APTES] under ambient conditions. Due to the facile interaction of heavy metals with primary amine sites and Zn-related intrinsic antimicrobial activity, toxicity assays of ZnACs nanoparticles (NPs) prior to their environmental and human-health applications are essential. However, such reports remain rare. Thus, in the present study, a cell viability assay of in-vitro HeLa cells comparing ZnCl2, Zn(NO3)(2) salts, and ZnO (similar to 50 mn average diameter) NPs was performed. Interestingly, compared with the ZnCl2, and Zn(NO3)(2) salts, and ZnO NPs (18.73/18.12/ 51.49 mu g/mL and 18.12/15.19/46.10 mu g/mL of IC50 values for 24 and 48 h), the two ZnACs NPs exhibited the highest toxicity (1050 values of 21.18/18.36 mu g/mL and 18.37/17.09 mu g/mL for 24 and 48 h, respectively), whose concentrations were calculated on Zn elemental composition. This might be due to the enhanced bioavailability and uptake into cells of ZnAC NPs themselves and their positively charged hydrophilicity by reactive oxygen species (ROS) generation, particularly as ZnACs exist in cationic NP's form, not in released Zn2+ ionic form (i.e., dissolved nanometal). However, in an in-vivo embryotoxicity assay in zebrafish, ZnACs and ZnO NPs showed toxic effects at 50-100 mu g/mL (corresponding to 37.88-75.76 of Zn wt% mu g/mL). The hatching rate (%) of zebrafish was lowest for the ZnO NPs, particularly where ZnAC-[(NO3)(2)] is slightly more toxic than ZnAC-[Cl-2]. These results are all very pertinent to the issue of ZnACs' potential applications in the environmental and biomedical fields.</P>

Induction of Hairy Roots and Characterization of Peroxidase Expression as a Potential Root Growth Marker in Sesame

Chun, J. -A.,Lee, J. -W.,Yi, Y. -B.,Park, G. -Y.,Chung, C. -H. Taylor Francis 2009 PREPARATIVE BIOCHEMISTRY AND BIOTECHNOLOGY Vol.39 No.4

<P> Using hypocotyl and cotyledon of sesame seedlings, hairy root cultures were established and cDNA coding for a peroxidase was cloned from the roots. The frequency of sesame hairy root formation was higher in hypocotyl (33.4%) than cotyledon (9.3%). Applicable levels of kanamycin and hygromycin as a selectable marker were 100 µg/mL and 30 µg/mL, respectively. The peroxidase cDNA showed relatively high sequence identity with and similarity to plant class III peroxidase family. The cDNA encoded polypeptide was identified with the presence of three sequence features: 1) the putative 4 disulfide bridges, 2) an ER-targeted signal sequence in the N-terminus, and 3) two triplets, NXS for glycosylation. A real-time RT-PCR exhibited an abrupt increase in the peroxidase transcription activity after 4-week cultures of the sesame hairy roots and its highest level in 6-week cultured hairy roots. In contrast, the growth pattern of sesame hairy roots showed a typical sigmoidal curve. The active hairy root growth began after 2-week culture and their stationary growth phase occurred after 5-week culture. These results suggested that the peroxidase expression patterns at its transcription level could be used a potential indicator signaling a message that there will be no longer active growth in hairy root cultures. The sesame peroxidase gene was differentially expressed in different tissues.</P>

Numerical modeling and experimental study of the influence of GDL properties on performance in a PEMFC

Chun, J.H.,Park, K.T.,Jo, D.H.,Kim, S.G.,Kim, S.H. Pergamon Press ; Elsevier Science Ltd 2011 International journal of hydrogen energy Vol.36 No.2

This work is to study the effect of properties of gas diffusion layer (GDL) on performance in a polymer electrolyte membrane fuel cell (PEMFC) by both numerical simulation and experiments. The 1-dimension numerical simulation using the mixture-phase model is developed to calculate polarization curve. We are able to estimate optimum GDL properties for cell performance from numerical simulation results. Various GDLs which have different properties are prepared to verify accuracy of the simulation results. The contact angle and gas permeability of GDLs are controlled by polytetrafluoroethylene (PTFE) content in micro-porous layers (MPLs). MPL slurry is prepared by homogeneous blending of carbon powder, PTFE suspension, isopropyl alcohol and glycerol. Then the slurry is coated on gas diffusion mediums (GDMs) surface with controlled thickness by blade coating method. Non-woven carbon papers which have different thicknesses of 200 μm and 380 μm are used as GDMs. The prepared GDLs are measured by surface morphology, contact angle, gas permeability and through-plane electrical resistance. Moreover, the GDLs are tested in a 25 cm<SUP>2</SUP> single cell at 70 <SUP>o</SUP>C in humidified H<SUB>2</SUB>/air condition. The contact angle of GDL increases with increasing PTFE content in MPL. However, the gas permeability and through-plane electrical conductivity decrease with increasing PTFE content and thickness of GDM. These changes in properties of GDL greatly influence the cell performance. As a result, the best performance is obtained by GDL consists of 200 μm thick non-woven carbon paper as GDM and MPL contained 20 wt.% PTFE content.

Evaluation of a commercial orthopaedic metal artefact reduction tool in radiation therapy of patients with head and neck cancer.

Kwon, H,Kim, K S,Chun, Y M,Wu, H-G,Carlson, J N K,Park, J M,Kim, J-I British Institute of Radiology 2015 The British journal of radiology Vol.88 No.1052

<P>To assess the image quality and dosimetric effects of the Philips orthopaedic metal artefact reduction (OMAR) (Philips Healthcare System, Cleveland, OH) function for reducing metal artefacts on CT images of head and neck (H&N) patients.</P>

자동차 항법용 자이로 센서 시스템의 특성분석 및 Hybrid항법 알고리즘 개발

김상겸(S.G.Kim),최정훈(J.H.Choi),김정하(J.H.Kim),전진홍(J.H.Chun),양승규(S.G.Yang) 한국자동차공학회 1997 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1997 No.6_1

Generally. G.P.S ( Global Positioning System ) is using for the car navigation system but it has some restrictions such as the discontinuity of earth satellites and SA ( Selective Availability ). Recently, the hybrid navigation system combining with G.P.S and Dead-Reckoning are much attractive for improving the accuracy of a vehicle positioning. G.P.S called satellite navigation system, can measure its position by using satellites. Dead-Reckoning is the self-contained navigation system, using wheel sensor for the vehicle velocity and gyro sensor for the vehicle angular velocity. Some algorithm could be generated for finding the vehicle position and orientation. In this paper, a Hybrid algorithm is developed and analyzed the characteristic of a Piezoelectric Vibrating Gyroscope & GPS.<br/>

Microstructural Characteristics of the Fuel Cladding Tubes Irradiated in Kori Unit 1

Kim H.G.,Baek J.H.,Lee M.H.,Chun Y.B.,Jeong Y.H. Korean Nuclear Society 2003 Nuclear Engineering and Technology Vol.35 No.5

In order to evaluate the microstructural characteristics of irradiated fuel claddings (Zircaloy-4), two irradiated specimens having different burnups (18 GWD/MTU and 42 GWD/MTU) were prepared from the G23-M4 fuel rods, which were loaded in Kori Unit 1 for 4 fuel cycles. The oxide thickness, hydride morphology and hardness change were characterized by an optical microscope and a micro-hardness tester after preparing the irradiated specimens in the PIE (Post Irradiation Examination) facilities. The dislocation loops and the amorphous transformation of precipitates induced by the neutron irradiation in the nuclear plant were also examined by a TEM. As the burnup increased from 18 GWD/MTU to 42 GWD/MTU, the oxide thickness increased from $6.0{\mu}m\;to\;25.3{\mu}m$ and the contents of hydrogen pick-up in the Zr matrix also greatly increased. In the comparison of the hardness of the unirradiated fuel cladding, the amount of hardness increase was nearly $9.3\%\;and\;24.2\%$ for the irradiated samples of 18 and 42 GWD/MTU, respectively. Both <a>-type dislocation loops and <c>-type dislocation components were observed simultaneously in the irradiated specimens and the densities of the dislocation was increased by increasing the burnup. The precipitates in both the irradiated specimens were amorphously transformed by the neutron irradiation and the trend of the amorphous transformation of the precipitates was enhanced at a higher burnup.

칡소의 염색체 양상과 핵형 분석

손시환,고영두,김두환,박구부,이정규,이철영,신철교,정희식,곽석준,박명구,천민성,백철승 한국축산학회 2000 한국축산학회지 Vol.42 No.1

The Korean Native Stripped Cattle known as Chickso have distinctive black hair belts all over the body to varying extents on a Hanwoo(Korean Cattle)-like yellowish brown background. These Battle are remaining only in a limited area of this country and are known to yield a flavorful meat somewhat distinct from that of Hanwoo, but their genetic lineage has not been identified. We have carried out karyotyping of these cattle firm the lymphocyte culture. Blood samples were collected from 20 of male and female cattle that had been bred at Poongjeon Farm located in Kosong, Kyongnam, and were subjected to chromosomal morphology and G- and C-banding analysis. Chickso, like Hanwoo, had 58 autosomes and X and Y sex chromosomes which were morphologically very similar to those of the latter. All the 58 autosomes revealed almost a zero value of centromeric index, suggesting that they are acrocentric; sex chromosomes X and Y were submetacentric and metacentric, respectively. Following G-banding, the light bands appeared near the centromeric site in all the autosomes whereas the specific dark bands were consistently visible in each homologous chromosome. Overall, the G-banding pattern was nearly identical between the Chickso and Hanwoo. C-bands representing the heterochromatin were present at or near the centromere in all the autosomes, whereas in sex chromosomes, they were found distributed on variable sites. The proportion of constitutive heterochromatin ranged 20∼30%. These patterns were not significantly different between the two subspecies. All of these cytogenetic results suggest that the distinctive traits of Chickso did not arise from a cytogenetic variation from Hanwoo, i. e. the former is simply a subpopulation of the latter. As such, we propose that selection and propagation of the Chickso based on economic traits may be advantageous to the domestic beef industry.

Roles of 14-3-3η in mitotic progression and its potential use as a therapeutic target for cancers

Lee, C G,Park, G-Y,Han, Y K,Lee, J H,Chun, S H,Park, H-Y,Lim, K-H,Kim, E-G,Choi, Y-J,Yang, K,Lee, C-W Macmillan Publishers Limited 2013 Oncogene Vol.32 No.12

14-3-3 proteins are involved in several cellular processes, including the G1/S and G2/M cell cycle transitions. However, their roles during mitosis are not well understood. Here, we showed that depletion of 14-3-3η, a 14-3-3 protein isoform, enhanced mitotic cell death, resulting in sensitization to microtubule inhibitors and inhibition of aneuploidy formation. The enhanced mitotic cell death by depletion of 14-3-3η appeared to be both caspase-dependent and independent. Furthermore, enhanced mitotic cell death and a reduction in aneuploidy following 14-3-3η depletion were independent of the mitotic checkpoint, which is thought to be the primary signaling event in the regulation of the cell death induced by microtubule inhibitors. When 14-3-3η depletion was combined with microtubule inhibitors in HCT116 and U87MG cells, it sensitized both cancer cell lines to microtubule inhibitors. These results collectively suggest that 14-3-3η may be required for mitotic progression and may be considered as a novel anti-cancer strategy in combination with microtubule inhibitors.

Activation of nuclear PTEN by inhibition of Notch signaling induces G2/M cell cycle arrest in gastric cancer

Kim, S-J,Lee, H-W,Baek, J-H,Cho, Y-H,Kang, H G,Jeong, J S,Song, J,Park, H-S,Chun, K-H Macmillan Publishers Limited 2016 Oncogene Vol.35 No.2

<P>Mutation in PTEN has not yet been detected, but its function as a tumor suppressor is inactivated in many cancers. In this study we determined that, activated Notch signaling disables PTEN by phosphorylation and thereby contributes to gastric tumorigenesis. Notch inhibition by small interfering RNA or.-secretase inhibitor (GSI) induced mitotic arrest and apoptosis in gastric cancer cells. Notch inhibition induced dephosphorylation in the C-terminal domain of PTEN, which led to PTEN nuclear localization. Overexpression of activated Notch1-induced phosphorylation of PTEN and reversed GSI-induced mitotic arrest. Dephosphorylated nuclear PTEN caused prometaphase arrest by interaction with the cyclin B1-CDK1 complex, resulting in their accumulation in the nucleus and subsequent apoptosis. We found a correlation between high expression levels of Notch1 and low survival rates and, similarly, between reduced nuclear PTEN expression and increasing the TNM classification of malignant tumours stages in malignant tissues from gastric cancer patients. The growth of Notch1-depleted gastric tumors was significantly retarded in xenografted mice, and in addition, PTEN deletion restored growth similar to control tumors. We also demonstrated that combination treatment with GSI and chemotherapeutic agents significantly reduced the orthotopically transplanted gastric tumors in mice without noticeable toxicity. Overall, our findings suggest that inhibition of Notch signaling can be employed as a PTEN activator, making it a potential target for gastric cancer therapy.</P>

Synthesis and characterization of crosslinked sulfonated poly(arylene ether sulfone) membranes for high temperature PEMFC applications

Park, K.T.,Chun, J.H.,Kim, S.G.,Chun, B.H.,Kim, S.H. Pergamon Press ; Elsevier Science Ltd 2011 International journal of hydrogen energy Vol.36 No.2

Sulfonated poly(arylene ether sulfone) copolymers containing carboxyl groups are prepared by an aromatic substitution polymerization reaction using phenolphthalin, 3,3'-disulfonated-4,4'-dichlorodiphenyl sulfone, 4,4'-dichlorodiphenyl sulfone and 4,4'-bisphenol A as polymer electrolyte membranes for the development of high temperature polymer electrolyte membrane fuel cells. Thin, ductile films are fabricated by the solution casting method, which resulted in membranes with a thickness of approximately 50μm. Hydroquinone is used to crosslink the prepared copolymer in the presence of the catalyst, sodium hypophosphite. The synthesized copolymers and membranes are characterized by <SUP>1</SUP>H NMR, FT-IR, TGA, ion exchange capacity, water uptake and proton conductivity measurements. The water uptake and proton conductivity of the membranes are decreased with increasing the degree of crosslinking which is determined by phenolphthalin content in the copolymer (0-15mol%). The prepared membranes are tested in a 9cm<SUP>2</SUP> commercial single cell at 80<SUP>o</SUP>C and 120<SUP>o</SUP>C in humidified H<SUB>2</SUB>/air under different relative humidity conditions. The uncrosslinked membrane is found to perform better than the crosslinked membranes at 80<SUP>o</SUP>C; however, the crosslinked membranes perform better at 120<SUP>o</SUP>C. The crosslinked membrane containing 10mol% of phenolphthalin (CPS-PP10) shows the best performance of 600mAcm<SUP>-2</SUP> at 0.6V and better performance than the commercial Nafion<SUP>(</SUP>R) 112 (540mAcm<SUP>-2</SUP> at 0.6V) at 120<SUP>o</SUP>C and 30 % RH.