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유강현,권오필,김동욱 대한화학회 2023 Bulletin of the Korean Chemical Society Vol.44 No.6
Methyl orange (MO) and its protonated derivatives were investigated at thedensity functional theory (DFT) level using CAM-B3LYP functional and 6-311+G(d,p) basis sets; their absorption spectra in aqueous solution were simu-lated, their relative stabilities in both the gas phase and the polar solutionswere calculated, and the activation energy barrier for thecis-to-transisomeriza-tion in both phases were computed. Except the protonation at the aminogroup, all the protonated isomers show a bathochromic shift of the mostintense absorption peak. In the gas phase, the sulfonate unit turns out to bethe most favorable proton acceptor. In the polar solutions, however, azogroups are more effective to accept the proton. The protonation at the azo Natom next to the phenyl-sulfonate group significantly reduces the energy bar-rier for thecis-to-transconversion in the aqueous solution, which suggests aswift conversion in the ground state.
Two-pore Domain Potassium Channels in Astrocytes
유강현,박재용 한국뇌신경과학회 2016 Experimental Neurobiology Vol.25 No.5
Two-pore domain potassium (K2P) channels have a distinct structure and channel properties, and are involved in a background K+ current. The 15 members of the K2P channels are identified and classified into six subfamilies on the basis of their sequence similarities. The activity of the channels is dynamically regulated by various physical, chemical, and biological effectors. The channels are expressed in a wide variety of tissues in mammals in an isoform specific manner, and play various roles in many physiological and pathophysiological conditions. To function as channels, the K2P channels form dimers, and some isoforms form heterodimers that provide diversity in channel properties. In the brain, TWIK1, TREK1, TREK2, TRAAK, TASK1, and TASK3 are predominantly expressed in various regions, including the cerebral cortex, dentate gyrus, CA1-CA3, and granular layer of the cerebellum. TWIK1, TREK1, and TASK1 are highly expressed in astrocytes, where they play specific cellular roles. Astrocytes keep leak K+ conductance, called the passive conductance, which mainly involves TWIK1-TREK1 heterodimeric channel. TWIK1 and TREK1 also mediate glutamate release from astrocytes in an exocytosis-independent manner. The expression of TREK1 and TREK2 in astrocytes increases under ischemic conditions, that enhance neuroprotection from ischemia. Accumulated evidence has indicated that astrocytes, together with neurons, are involved in brain function, with the K2P channels playing critical role in these astrocytes.
미국 및 유럽 의료기기 품목분류 체계 분석을 통한 국내 의료기기 품목분류 개선 연구
유강현,손지민,권경민,김유림,이희성,장원석 대한의용생체공학회 2023 의공학회지 Vol.44 No.1
The purpose of this study is to derive medical devices with different management systems through com- parison of domestic and overseas medical device product classification systems and to propose management con- version measures for the products. The definitions of medical devices were compared and the scope of medical devices defined by each country was confirmed through surveys of the Medical Device Act, Federal Food, Drug & Cosmetics Act (FD&C) in the U.S., and Medical Device Regulations (MDR) in Europe. Using the Ministry of Food and Drug Safety’s regulations on medical device products and grades, 21 CFR part 860-892 and product code clas- sification files in U.S., and EMDN in Europe as basic data to compare medical device products and derive medical devices with different management systems. As a result of comparing the definition and product classification sys- tems of medical devices in Korea, the U.S. and Europe, medical device accessories, prosthetic limbs and aids among assistive devices for persons with disabilities, drugs, quasi-drugs and industrial products that are not managed by medical devices in Korea are managed as medical devices in the U.S. and Europe. This study aims to improve public health by securing systematic product safety management and essential performance under med- ical device regulations. Management within a single medical device system will increase the efficiency of licensing work of domestic medical device manufacturers and related organizations. It is also expected to help advance the system according to the international harmony of the item classification system and enhance smooth import and export competitiveness.
주요국의 의료기기 품목 분류체계 조사분석을 통한 국내 의료기기 품목 신설 및 세분화 연구
손지민,유강현,김유림,권경민,이희성,장원석 대한의용생체공학회 2023 의공학회지 Vol.44 No.1
With the international change in the medical device market owing to the development of innovative med- ical engineering and the use of various raw materials, a systematic and rational medical device classification system is needed to safely manage newly developed medical devices. This study aims to improve the domestic medical device classification system by proposing product establishment and segmentation. It is based on medical device products from the United States and Europe that are only available in foreign systems and are more subdivided than domestic products. This study analyzes and compares the domestic and foreign medical device classification systems by examining laws, guidelines, and analysis reports in Korea, the United States, and Europe. In accordance with prod- uct establishment and segmentation criteria, products subject to improvement are presented. This study contributes to safely managing medical devices that do not fit with the current classification system and to solving the confusion caused by the lack of international harmony in product classification systems.