Regulation of Expression of the Bacillus caldolyticus Pyrimidine Biosynthetic Operon by pyrR Gene, an Autogenous Regulator

Ghim, Sa-Youl Korean Society of Life Science 2001 Journal of Life Science Vol.11 No.2

The pyrR gene of the pyrimidine biosynthesis (pyr) operon of the thermophile Bacillus caldolyticus, encoding a uracil phosphoribosyltransferase (UPRTase), turned to rely as a pyr operon regulator. It has been proposed that PyrR mediates transcriptional termination-antitermination at three intercistronic regions of the par operon (S.-Y Ghim and J. Neuhard, J. Bacteriol.,176, 3698-3707, 1994). In this research, a plasmid carrying the pyrR region of B. caldolyticus could restore a pyrimidine regulation in a pyrR mutant of B. subtilis. Expression of pyrR was found to increase 6-7 fold during pyrimidine starvation. Additionally, a highly conserved nucleotide sequence which may constitute the binding site for a PyrR protein (PyrR-binding loop) in transcript was staggested. Alternative antiterminator and terminator structures involving three conserved motifs in front of the pyrR, pyrP and pyrB genes, respectively, are proposed to account for the observed regulation pattern.

A Commentary on Air Pollution Monitoring Programs in Korea

Ghim, Young-Sung,Kim, Jin-Young,Shim, Shang-Gyoo,Moon, Kill-Choo Korean Society for Atmospheric Environment 2002 한국대기환경학회지 Vol.18 No.E1

Air quality issues in Korea rapidly changed at the beginning of the 1990s from primary to secondary pollutants starting in Seoul, the capital of Korea. The present frame of national air pollution monitoring networks was established between the end of the 1980s and the beginning of the 1990s. Background monitoring was initiated in the middle of the 1990s in response to increasing public concern about the long-range transport of air pollutants. Apart from the national monitoring, both routine and intensive measurements of fine particles have been made for research purposes since the middle of the 1990s at several background sites. However, air pollution monitoring in urban areas for other purposes was relatively scarce as national monitoring has been concentrated in these areas. Although ozone pollution has become a significant issue in major metropolitan areas every summer, only a little information on ozone precursors is available. During the past few years, the number of national monitoring stations has greatly increased. The government has a plan to gradually expand monitoring items as well as stations. It is anticipated that highly detailed information on both photochemical reactants and products will be available within the next several years. More emphasis will be placed on toxic substances based on risk assessment in monitoring for both research and policy making.

INHIBITION OF HUMAN NEUTROPHIL ELASTASE BY DIFFERENT CLASSES OF ANTIBIOTICS

Ghim, Sa-Youl,Kang, Kooil 고신대학교 의학부 1988 高神大學校 醫學部 論文集 Vol.4 No.1

사람의 혈액에 있는 호중구 엘라스테이즈에 관한 연구의 진척은, 약물로 사용가능한 생체내 혹은 인공합성의 저해제 개발을 동반해 오고 있다. 정제된 호중구 엘라스테이즈에 12종의 항생제를 처리하였더니 20mM 미만의 lC_(50)을 보인 것은 oxytetracycline, cefamandole, gentamicin, amikacin, cloxacillin, methicillin, chloramphenicol 등이었고, 10mM 농도에서 50% 이상의 저해율을 나타낸 것은 methicillin, cefamandole, oxytetracycline 등이었다. 그 결과는 세포벽 합성이나 단백질 합성을 저해하는 일반적 항생제의 약리학적 기전과는 다른 차원에서 항생제가 숙주의 조직을 보호할 수 있는 가능성을 보여준 모델이 존재한다는 것을 in vitro 실험에서 확인할 수 있었다.

Dry Deposition of Reactive Nitrogen and Sulfur Compounds in the Greater Seoul Area

Ghim, Young Sung,Kim, Jin Young 한국화학공학회 2002 Korean Journal of Chemical Engineering Vol.19 No.1

While deposition is a removal process of pollutants from the atmosphere, it is an intake process of such pollutants into the ground. It is suggested that surface waters in the Greater Seoul Area, used as a source of drinking water, have been affected by severe air pollution. In this work, the dry deposition of reactive nitrogen and sulfur species was estimated for three typical days in each season for the year of 1997. The CIT (California Institute of Technology) photochemical model incorporated with a gaseous oxidation reaction of SO_2 was used. The study revealed that reactive nitrogen deposition was the largest in summer and sulfur deposition was the largest in winter. Most of the reactive nitrogen was deposited in the form of HNO_3 and NO_2, but HNO_3 deposition is highly dependent on the season according to the extent of photochemical production. On the other hand, the contribution of sulfate to the total deposition of sulfur was minimal partly because of low deposition velocity and of the neglect of possible inflow from the boundaries. Approximately 53% of the reactive nitrogen and 30% of the sulfur emitted in the study area was deposited in the ground in the dry form on an annual basis.

Experimental evaluation of the in-tube condensation heat transfer of pure n-pentane/R245fa and their non-azeotropic mixture as an ORC working fluid

Ghim, G.,Lee, J. Pergamon ; Elsevier Science Ltd 2016 Applied thermal engineering Vol.106 No.-

The existence of temperature gliding in non-azeotropic mixture working fluids provides a promising opportunity for greatly improved resource utilization in organic Rankine cycle (ORC) systems for geothermal applications. The condensation heat transfer degradation associated with working fluid mixtures is an unavoidable penalty that may reduce the utilization and system benefits by necessitating larger heat exchangers. The objective of the current study is an experimental investigation of condensation heat transfer for R245fa, n-pentane, and a composition of their mixture. Quasi-local condensation heat transfer coefficients are measured in a straight horizontal smooth tube with flow conditions at mass flux G=100 and 150kg(m<SUP>2</SUP>s)<SUP>-1</SUP>, local equilibrium quality x=0.05-0.80, and reduced pressures P<SUB>r</SUB>=0.05-0.15. The reduced condensation heat transfer coefficients from the test are compared with the predictions from already established mixture correction methods in the literature. Pure components R245fa and n-pentane condensation heat transfer data are well predicted by Shah (1979) correlations for all test conditions. However, their non-azeotropic mixture condensation heat transfer data require additional correction parameter to account for the heat transfer degradation. This correction parameter is correlated by the temperature gliding gradient of mixture fluids. Test data with mixture working fluids from current study are reasonably well predicted by the corrected in-tube correlation.

Hepatic cell encapsulation using a decellularized liver scaffold

Ghim, J. H.,Hussein, K. H.,Park, K. M.,Woo, H. M. Springer Science + Business Media 2015 Biomedical Engineering Letters (BMEL) Vol.5 No.1

Endothelial Deletion of Phospholipase D2 Reduces Hypoxic Response and Pathological Angiogenesis

Ghim, Jaewang,Moon, Jin-Sook,Lee, Chang Sup,Lee, Junyeop,Song, Parkyong,Lee, Areum,Jang, Jin-Hyeok,Kim, Dayea,Yoon, Jong Hyuk,Koh, Young Jun,Chelakkot, Chaithanya,Kang, Byung Jun,Kim, Jung-Min,Kim, Ky American Heart Association, Inc. 2014 Arteriosclerosis, thrombosis, and vascular biology Vol.34 No.8

<P><B>Objective—</B></P><P>Aberrant regulation of the proliferation, survival, and migration of endothelial cells (ECs) is closely related to the abnormal angiogenesis that occurs in hypoxia-induced pathological situations, such as cancer and vascular retinopathy. Hypoxic conditions and the subsequent upregulation of hypoxia-inducible factor-1α and target genes are important for the angiogenic functions of ECs. Phospholipase D2 (PLD2) is a crucial signaling mediator that stimulates the production of the second messenger phosphatidic acid. PLD2 is involved in various cellular functions; however, its specific roles in ECs under hypoxia and in vivo angiogenesis remain unclear. In the present study, we investigated the potential roles of PLD2 in ECs under hypoxia and in hypoxia-induced pathological angiogenesis in vivo.</P><P><B>Approach and Results—</B></P><P><I>Pld2</I> knockout ECs exhibited decreased hypoxia-induced cellular responses in survival, migration, and thus vessel sprouting. Analysis of hypoxia-induced gene expression revealed that PLD2 deficiency disrupted the upregulation of hypoxia-inducible factor-1α target genes, including <I>VEGF</I>, <I>PFKFB3</I>, <I>HMOX-1</I>, and <I>NTRK2</I>. Consistent with this, PLD2 contributed to hypoxia-induced hypoxia-inducible factor-1α expression at the translational level. The roles of PLD2 in hypoxia-induced in vivo pathological angiogenesis were assessed using oxygen-induced retinopathy and tumor implantation models in endothelial-specific <I>Pld2</I> knockout mice. <I>Pld2</I> endothelial-specific knockout retinae showed decreased neovascular tuft formation, despite a larger avascular region. Tumor growth and tumor blood vessel formation were also reduced in <I>Pld2</I> endothelial-specific knockout mice.</P><P><B>Conclusions—</B></P><P>Our findings demonstrate a novel role for endothelial PLD2 in the survival and migration of ECs under hypoxia via the expression of hypoxia-inducible factor-1α and in pathological retinal angiogenesis and tumor angiogenesis in vivo.</P>

3D surface mapping of freeform optics using wavelength scanning lateral shearing interferometry.

Ghim, Young-Sik,Rhee, Hyug-Gyo,Davies, Angela,Yang, Ho-Soon,Lee, Yun-Woo Optical Society of America 2014 Optics express Vol.22 No.5

<P>Freeform optics have emerged as promising components in diverse applications due to the potential for superior optical performance. There are many research fields in the area ranging from fabrication to measurement, with metrology being one of the most challenging tasks. In this paper, we describe a new variant of lateral shearing interferometer with a tunable laser source that enables 3D surface profile measurements of freeform optics with high speed, high vertical resolution, large departure, and large field-of-view. We have verified the proposed technique by comparing our measurement result with that of an existing technique and measuring a representative freeform optic.</P>

Spectrally resolved white-light interferometry for 3D inspection of a thin-film layer structure

Ghim, Young-Sik,Kim, Seung-Woo The Optical Society 2009 Applied Optics Vol.48 No.4

<P>We describe an improved scheme of spectrally resolved white-light interferometry, which provides 3D visual inspection of a thin-film layer structure with nanometer level resolutions. Compared to the authors' previous method [Appl. Phys. Lett.91, 091903 (2007)APPLAB0003-695110.1063/1.2776015], 3D tomographic information of thin films can be obtained by decoupling the film thickness and top surface profile, which is embodied by inducing spectral carrier frequency to the reference arm and applying a low-pass filter to the interferogram instead of two troublesome measurement steps of activating and deactivating a mechanical shutter. We test and verify our proposed method by measuring a patterned thin-film layer structure as well as standard specimens of thin films with various thicknesses.</P>

INHIBITION OF HUMAN NEUTROPHIL ELASTASE BY KIFFERENT CLASSES OF ANTIBIOTICS

Ghim, Sa Youl,Kang, Koo Il 高神大學 醫學部 1988 高神大學醫學部 論文集 Vol.4 No.1