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Lee, Hoe-Suk,Park, Jisu,Yoo, Young Je,Yeon, Young Joo Elsevier 2019 Enzyme and microbial technology Vol.125 No.-
<P><B>Abstract</B></P> <P>2-Hydroxy acid dehydrogenases (2-HADHs) have been implicated in the synthesis of 2-hydroxy acids from 2-oxo acids that are used in wide areas of industry. <SMALL>D</SMALL>-lactate dehydrogenases (<SMALL>D</SMALL>-LDHs), a subfamily of 2-HADH, have been utilized to this purpose, yet they exhibited relatively low catalytic activity to the 2-oxo acids with large functional groups at C<SUB>3</SUB>. In this report, four putative 2-HADHs from <I>Oenococcus oeni</I>, <I>Weissella confusa</I>, <I>Weissella koreensis</I> and <I>Pediococcus claussenii</I> were examined for activity on phenylpyruvate (PPA), a substrate to 3-phenyllactic acid (PLA) with a C<SUB>3</SUB> phenyl group. The 2-HADH from <I>P. claussenii</I> was found to have the highest <I>k</I> <SUB>cat</SUB>/<I>K</I> <SUB>m</SUB> on PPA with 1,348.03 s<SUP>−1</SUP> mM<SUP>−1</SUP> among the four enzymes with higher substrate preference for PPA than pyruvate. Sequential, structural and mutational analysis of the enzyme revealed that it belonged to the <SMALL>D</SMALL>-LDH family, and phenylalanine at the position 51 was the key residue for the PPA binding to the active site <I>via</I> hydrophobic interaction, whereas in the 2-HADHs from <I>O. oeni</I> and <I>W. confusa</I> the hydrophilic tyrosine undermined the interaction. Because phenyllactate is a potential precursor for pharmaceutical compounds, antibiotics and biopolymers, the enzyme could increase the efficiency of bio-production of valuable chemicals. This study suggests a structural basis for the high substrate preference of the 2-HADH, and further engineering possibilities to synthesize versatile 2-hydroxy acids.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A novel <SMALL>D</SMALL>-LDH with high substrate preference for phenylpyruvate (PPA) was discovered. </LI> <LI> The catalytic efficiency of <SMALL>D</SMALL>-LDH from <I>P. claussenii</I> with PPA was 1,348 (s<SUP>−1</SUP> mM<SUP>−1</SUP>). </LI> <LI> Biochemical, phylogenetic and structural analysis for the enzymes were investigated. </LI> <LI> Phenyl ring of PPA interacts hydrophobically with phenylalanine in the active site. </LI> <LI> Structural analysis provides new engineering possibilities for <SMALL>D</SMALL>-LDHs. </LI> </UL> </P>
A dose monitoring system for dental radiography
Lee, Chena,Lee, Sam-Sun,Kim, Jo-Eun,Symkhampha, Khanthaly,Lee, Woo-Jin,Huh, Kyung-Hoe,Yi, Won-Jin,Heo, Min-Suk,Choi, Soon-Chul,Yeom, Heon-Young Korean Academy of Oral and Maxillofacial Radiology 2016 Imaging Science in Dentistry Vol.46 No.2
Purpose: The current study investigates the feasibility of a platform for a nationwide dose monitoring system for dental radiography. The essential elements for an unerring system are also assessed. Materials and Methods: An intraoral radiographic machine with 14 X-ray generators and five sensors, 45 panoramic radiographic machines, and 23 cone-beam computed tomography (CBCT) models used in Korean dental clinics were surveyed to investigate the type of dose report. A main server for storing the dose data from each radiographic machine was prepared. The dose report transfer pathways from the radiographic machine to the main sever were constructed. An effective dose calculation method was created based on the machine specifications and the exposure parameters of three intraoral radiographic machines, five panoramic radiographic machines, and four CBCTs. A viewing system was developed for both dentists and patients to view the calculated effective dose. Each procedure and the main server were integrated into one system. Results: The dose data from each type of radiographic machine was successfully transferred to the main server and converted into an effective dose. The effective dose stored in the main server is automatically connected to a viewing program for dentist and patient access. Conclusion: A patient radiation dose monitoring system is feasible for dental clinics. Future research in cooperation with clinicians, industry, and radiologists is needed to ensure format convertibility for an efficient dose monitoring system to monitor unexpected radiation dose.
Lee, Jeong-Ha,Eom, Sung-Hwan,Lee, Eun-Hye,Jung, Yeoun-Joong,Kim, Hyo-Jung,Jo, Mi-Ra,Son, Kwang-Tae,Lee, Hee-Jung,Kim, Ji Hoe,Lee, Myung-Suk,Kim, Young-Mog The Korean Society of Phycology 2014 ALGAE Vol.29 No.1
To develop effective and safe acne vulgaris therapies with a continuing demand for new solutions, we investigated unique efficacy of an antibacterial agent from marine brown alga Eisenia bicyclis in treating acne vulgaris. The methanolic extract of E. bicyclis exhibited potential antibacterial activity against acne-related bacteria. The ethyl acetate fraction showed the strongest antibacterial activity against the bacteria among solvent fractions. Six compounds (1-6), previously isolated from the ethyl acetate fraction of E. bicyclis, were evaluated for antibacterial activity against acne-related bacteria. Among them, compound 2 (fucofuroeckol-A [FF]) exhibited the highest antibacterial activity against acne-related bacteria with a minimum inhibitory concentration (MIC) ranging from 32 to $128{\mu}g\;mL^{-1}$. Furthermore, FF clearly reversed the high-level erythromycin and lincomycin resistance of Propionibacterium acnes. The MIC values of erythromycin against P. acnes were dramatically reduced from 2,048 to $1.0{\mu}g\;mL^{-1}$ in combination with MIC of FF ($64{\mu}g\;mL^{-1}$). The fractional inhibitory concentration indices of erythromycin and lincomycin were measured from 0.500 to 0.751 in combination with 32 or $64{\mu}g\;mL^{-1}$ of FF against all tested P. acnes strains, suggesting that FF-erythromycin and FF-lincomycin combinations exert a weak synergistic effect against P. acnes. The results of this study suggest that the compounds derived from E. bicyclis can be a potential source of natural antibacterial agents and a pharmaceutical component against acnerelated bacteria.
Lee Kyung-Hee,Lee Sun-Bok,An Chang-Hyeon,Heo Min-Suk,Yi Won-Jin,Huh Kyung-Hoe,Park Moo-Soon,Lee Sam-Sun,Choi Soon-Chul Korean Academy of Oral and Maxillofacial Radiology 2004 Imaging Science in Dentistry Vol.34 No.4
Purpose: The purpose of this study is to examine the effects of X-ray beam angulation on the fractal dimension of trabecular bone structure of human dry mandible using the tile counting method. Materials and Methods: We divided 5 human dry mandibles into an angle and a molar groups depending on the regions and deciding the region of interest (ROI). When contrasted with the ROI, the inferior cortex was appointed to be low and the lines perpendicular to the buccal cortex were appointed to be the standard angle. Direct digital intraoral radiographs were obtained from 9 different projection angles. We analyzed statistically the fractal dimension using the tile counting method. Results: There was a statistically significant difference in the fractal dimension of the regions and the mandibles, but there was no statistically significant difference in the fractal dimension according to the X-ray beam angulation. Conclusion : There is no statistically significant effect of the angle of the projection on the fractal dimension of trabecular bone structure of a human dry mandible according to the tile counting method.