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Lee, H. G,P. Y. Lee,Y. K. Lee,S. J. Kim,H. K. Chung,M. K. Seo,J. K. Park,K. S. Min,W. K. Chang 한국동물생명공학회(구 한국동물번식학회) 2003 Reproductive & developmental biology Vol.27 No.4
The effects of additions/deletions in glycosylated residues of recombinant human EPO (rhEPO) produced in CHO-K1 on their secretion were examined. hEPO cDNA was amplified from human liver mRNA and cloned into the pCR2.1 TOPO. Using overlapping-extension site-directed mutagenesis method, glycosylation sites at 24th, 38th, 83rd, and 126th were respectively or accumulatively removed by substituting its asparagine (or serine) with glutamine. To add novel glycosylation sites, 69 and 105th leucine was mutated to asparagine. Mutant and wild type rhEPO constructs were cloned into the pcDNA3 expression vector with CMV promoter and transfected into CHO cell line, CHO-K1, to produce mutant rhEPO mutant rhEPO proteins. Enzyme-linked immunosorbant assay (ELISA) and Western analysis with monoclonal anti-EPO antibody were performed using supernatants of the cultures showing transient and stable expressions respectively. Addition of novel glycosylation reduced rhEPO secretion dramatically while deletion mutants had little effect except some double deletion mutants (△24/83 and △38/83) and triple mutant (△24/38/83). This fact suggests that not single but combination of changes in glycosyl groups affect secretion of rhEPO in cell culture, possibly via changes in their conformations.
Global DNA Methylation of Porcine Embryos during Preimplantation Development
Yeo S. E,Y. K. Kang,D. B. Koo,J. S. Han,K. Yu,C. H. Kim,H. Park,W. K. Chang,K. K. Lee 한국동물생명공학회(구 한국동물번식학회) 2003 Reproductive & developmental biology Vol.27 No.4
DNA methylation at CpG sites, which is a epigenetic modification, is associated with gene expression without change of DNA sequences. During early mouse embryogenesis, dynamic changes of DNA methylation occur. In this study, DNA methylation patterns of porcine embryos produced in vivo and in vitro were examined at various developmental stages by the immunocytochemical staining method. Interestingly, active demethylation was not observed on the paternal pronucleus of porcine zygotes. However, differences were detected in the passive demethylation process between in vivo and in vitro embryos. There was no change in the DNA methylation state until the blastocyst stage of in vivo embryos, whereas partial demethylation was observed in several blastomeres from a 4 cell stage to a morula stage of in vitro embryos. The whole genome of inner cell mass (ICM) and trophectoderm (TE) cells in porcine blastocysts were evenly methylated without de novo methylation. Our findings demonstrate that genome-wide demethylation does not occur in pig embryos during preimplantation development unlike murine and bovine embryos. It indicates that the machinery regulating epigenetic reprogramming may be different between species.
Sphingomonas aestuarii sp. nov., isolated from tidal flat sediment
Roh, S. W.,Kim, K.-H.,Nam, Y.-D.,Chang, H.-W.,Kim, M.-S.,Oh, H.-M.,Bae, J.-W. Microbiology Society 2009 International journal of systematic and evolutiona Vol.59 No.6
<P>A novel bacterium (strain K4(T)) belonging to the genus Sphingomonas was isolated from tidal flat sediment in Korea. Its morphology, physiology, biochemical features and 16S rRNA gene sequence were characterized. Colonies of this strain are yellow in colour and the cells are rod-shaped, exhibiting negative Gram staining. The strain grows at 0-5 % (w/v) NaCl and 20-35 degrees C, with optimal growth occurring at 0 % (w/v) NaCl and 30 degrees C. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain K4(T) is associated with the genus Sphingomonas. Within the phylogenetic tree, this novel strain shares a branching point with Sphingomonas asaccharolytica Y-345(T), with which it shares 97.3 % 16S rRNA gene sequence similarity. The polyamine pattern predominantly contains the Sphingomonas-specific triamine sym-homospermidine. Combined analysis of 16S rRNA gene sequences, DNA-DNA relatedness, physiological and biochemical test results identified genotypic and phenotypic differences between strain K4(T) and other Sphingomonas species. On the basis of these differentiating features, it is concluded that strain K4(T) (=KCTC 22050(T)=DSM 19475(T)) represents a novel species of the genus Sphingomonas, for which the name Sphingomonas aestuarii sp. nov. is proposed.</P>
1987년 한국에서 발생한 렙토스피라병의 혈청역학적 조사
이증훈,박영수,이우곤,김석용,정선식,우준희,박성광,박경희,송영욱,김선영,기정일,최두혁,강성귀,김주완,최강원,김우열,최명식,최인학,장우현,윤성열 대한감염학회 1988 감염 Vol.20 No.3
Human leptospirosis was an unfamiliar disease in Korea until 1984 that outbreak of leptospirosis occurred among farmers and soldiers after field works for harvesting rice. During that time, Lee and Jo confirmed the first Korean cases of leptospirosis by serological test, isolation of causative agent and autopy findings. Afterward several outbreaks occurred also during autumn especially after flood in every years and some characterisitcs of leptospirosis in Korea such as clinical manifestations, serotypes and seroepidemiological features has been revealed by many investigators. Because of the major mode of transmission between rodents and human is by direct contact with leptospiral urine of rodents or contaminated soil by the urine, leptospirosis in Korea has been primarily a disease of person in occupations heavily exposed to contaminated soil or infected urine such as farmer, army and etc. Therefore it seems that leptospirosis is one of the main communicable diseases to be controlled urgently in Korea, for an agricultural people account for almost half of total Korean people. For clarifying the seroepidemiological patterns of human leptospirosis in Korea by sex, month region and main reacting serovars of L. interrogans among acute febrile disease occurred in 1987, 1,773 patient's sers with acute febrile episodes were tested by microagglutination test using 19 representative strains of leptospiral serogroup as antigen. All of those sera were collected from 10 collaborative clinics located in Kyunggi, Kangwon, Chungbuk, Chungnam, Chonbuk, Chonnam province and Seoul. The results wee summerized as follows. 1) Among 1,773 sera of patients with acute febrile episodes, 219 (12.4%) were seropositive to L. interrogans, 487(27.5%) to R. tsutsugamushi, 241(13.6%) to R.typhi and 160(90.0%) to Hantaan virus. 2) Among seropositives to L.interrogans, the male outnumbered the female, 65% and 35%. 3) For age distribution, 26.9% of seropositives to L.interrogans were fifties, 19.6% were forties, 9.1% were sixties, 5.9% were thirties and 4.1% were twenties. 4) Eighty three percent of seropositives had occurred between September and October in 1987 with a peak in September. 5) Main leptospiral serovars reactive to patient's sera were Icterohaemorrhagiae(54.3%), Canicola(31.0%), CH-48(13.2%), Tarassovi(0.9%)and Cynopteri(0.5%). 6) For regional distribution, 65.8% of seropositives to L.interrogans were residents from Chonbuk, 12.3% were Chonnam, 7.3% were Chungnam, 5.5% were Kyunggi and 1.4% were Kangwon.
Shiu, S. H.,Kohri, H.,Chang, W. C.,Ahn, D. S.,Ahn, J. K.,Chen, J. Y.,Daté,, S.,Ejiri, H.,Fujimura, H.,Fujiwara, M.,Fukui, S.,Gohn, W.,Hicks, K.,Hotta, T.,Hwang, S. H.,Imai, K.,Ishikawa, T.,Joo, American Physical Society 2018 Physical Review C Vol.97 No.1
<P>We report the measurement of the gamma p -> K+Lambda and gamma p -> K+Sigma(0) reactions at SPring-8. The differential cross sections and photon-beam asymmetries are measured at forward K+ production angles using linearly polarized tagged-photon beams in the range of E-gamma = 1.5-3.0 GeV. With increasing photon energy, the cross sections for both gamma p -> K+Lambda and gamma p -> K+Sigma(0) reactions decrease slowly. Distinct narrow structures in the production cross section have not been found at E gamma = 1.5-3.0 GeV. The forward peaking in the angular distributions of cross sections, a characteristic feature of t-channel exchange, is observed for the production of Lambda in the whole observed energy range. A lack of similar feature for Sigma(0) production reflects a less dominant role of t-channel contribution in this channel. The photon-beam asymmetries remain positive for both reactions, suggesting the dominance of K* exchange in the t channel. These asymmetries increase gradually with the photon energy, and have a maximum value of +0.6 for both reactions. Comparison with theoretical predictions based on the Regge trajectory in the t channel and the contributions of nucleon resonances indicates the major role of t-channel contributions as well as non-negligible effects of nucleon resonances in accounting for the reaction mechanism of hyperon photoproduction in this photon energy regime.</P>
Chang, H . K .,Kim, S . G .,Cheong, B .,Kim, W . M .,Chung, M .,Lee, T . S .,Lee, J . K . 대한금속재료학회(대한금속학회) 1998 METALS AND MATERIALS International Vol.4 No.6
Constant-pressure molecular dynamics simulations are carried out to study the liquid-amorphous-crystalline transition behavior in a model system composed of 500 Leonard-Jones particles under three-dimensional periodic boundary conditions. The critical quenching rate (CQR) for amorphization, i.e., the minimum rate above which no crystallization occurs on quenching, is found to be about 5.52 × 10^(12) K/s for a one-component, unary system. For lower quenching rates, the amorphous phase transforms to a crystalline phase with 0.30.5 of the melting point as the transition temperature. A binary system with a misfit in atomic size shows a smaller CQR, while a system with a higher bond strength for solute atoms requires a greater CQR. A crystallizakion behavior of an amorphous phase on repeating is also studied. Its crystallization temperature depends on the history: the higher the quenching rate for amorphization, the higher the crystallization temperature.
Aerospatiale A-airfoil 주위 천이-난류 유동의 대와류모사기법 적용에서의 격자영향 연구
최지원(J.W. Choi),장경식(K.S. Chang),이상욱(S.W. Lee),김건홍(G.H. Kim) 한국전산유체공학회 2019 한국전산유체공학회지 Vol.24 No.2
In this study, the grid effect based on WALE LES model is analyzed using the open source OpenFOAM. The numerical analysis is performed on the flow around the Aerospatiale A-airfoil of high Reynolds number, Rec=2.1×10<SUP>6</SUP>. Four grid systems with different grid resolutions in the streamwise and spanwise directions are considered to be compared with reference data. Mean velocity profiles and pressure distributions are presented according to the different grid systems and time averaged drag and lift coefficients are compared. Reynolds stress profiles also are presented. As the grid resolution increases, the prediction of transitional flow features and the fluctuations in turbulent flow are better. However, it is confirmed that higher gird resolution is required for better quantitative agreement with experimental data.