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Identification of hyperacute ischemic stroke with a more homogenous nature
Yi, Kyung,Lee, Hong,Lee, Sang-Rae,Lee, Youngjeon,Lee, Seung,Lee, Chulhyun,Cha, Sang-Hoon De Gruyter Open Sp. z o.o. 2014 Translational neuroscience Vol.5 No.2
<B>Abstract</B><P>Previous reports revealed that middle cerebral artery occlusion (MCAO) models in rats were very diverse in nature, and experimental stroke of a more homogenous nature had not been previously documented. This paper aims to present our novel observations of experimental stroke in rats with similar MRI characteristics after MCAO. Immediately after MCAO, 19 rats were placed into a 4.7 T MRI scanner, and diffusion weighted imaging (DWI) of axial and coronal planes was repeated every 10 minutes up to post-occlusion 115 minutes. Apparent diffusion coefficient (ADC) values of the ischemic lesions were calculated and compared to those of the unaffected contra-lateral hemispheres. Successful MCAO was defined when the whole left MCA territory showed ADC abnormality on DWI. Percentage of hemispheric lesion volume (% HLV), relative ADC value (rADC), and relative DWI signal intensity (rDWI) were serially evaluated for quantitative analysis of ADC-derived lesion characteristics. Successful MCA territorial infarction was induced in nine rats (9/19, 47.4%). In quantitative analysis of ADC-derived lesion characteristics, lesion volumes of seven rats (group 1) were very similar, but larger than those of the other two rats (group 2): % HLV of initial MRI = 45.4 ± 2.5 / 19.1 ± 6.6. rADCs and rDWIs of group 1 showed similar patterns of temporal change, which was different from those of group 2. Using prospective diffusion MRI after MCAO in rats, we identified territorial hyperacute ischemic lesions with similar MRI characteristics. This observation would contribute to the establishment of more homogenous rodent models for ischemic stroke translational research.</P>
Synthesis of highly magnetic graphite-encapsulated FeCo nanoparticles using a hydrothermal process
Lee, Seung Jae,Cho, Jee-Hyun,Lee, Chulhyun,Cho, Janggeun,Kim, Yong-Rok,Park, Joung Kyu IOP Pub 2011 Nanotechnology Vol.22 No.37
<P>The graphite encapsulation of metal alloy magnetic nanoparticles has attracted attention for biological applications because of the high magnetization of the encapsulated particles. However, most of the synthetic methods have limitations in terms of scalability and economics because of the demanding synthetic conditions and low yields. Here, we show that well controlled graphite-encapsulated FeCo core–shell nanoparticles can be synthesized by a hydrothermal method, simply by mixing Fe/Co with sucrose as a carbon source. Various Fe/Co metal ratios were used to determine the compositional dependence of the saturation magnetization and relaxivity coefficient. Transmission electron microscopy indicated that the particle sizes were 7 nm. In order to test the capability of graphite-encapsulated FeCo nanoparticles as magnetic resonance imaging (MRI) contrast agents, these nanoparticles were solubilized in water by the nonspecific physical adsorption of sodium dodecylbenzene sulfonate. </P>
시설 채소 토경 관비재배를 위한 관비 처방 프로그램 개발
이예진 ( Yejin Lee ),이찬욱 ( Chanwook Lee ),이슬비 ( Seulbi Lee ),현병근 ( Bynggeun Hyun ),송요성 ( Yosung Song ),김양민 ( Yangmin X. Kim ),류철현 ( Chulhyun Yoo ) 한국환경농학회 2021 한국환경농학회 학술대회집 Vol.2021 No.-
국내 시설재배지 토경재배 면적은 약 89%이며, 대부분의 농가에서 물과 비료를 같이 공급하는 관수 시설을 보유하고 있다. 시설재배의 특성상 연중 내내 재배를 하고, 작물 재배 중 지속적으로 비료를 공급하기 때문에 시설재배지 토양의 염류집적 문제를 피하기 어려운 상황이다. 주로 농가의 경험에 의존하여 비료성분 함량이 높은 수입산 관주용 비료를 많이 사용하기 때문에 과다한 비료를 사용할 우려가 있고, 경영비 또한 상승할 수 있다. 본 연구에서는 시설 토경 관비재배지에서 작물 생육시기에 따라 필요한 물과 비료량을 설정하고, 1주 단위로 물과 비료를 처방하는 시스템을 개발하였다. 대상작물은 애호박, 수박, 멜론, 가지, 풋고추, 딸기, 단고추, 토마토, 오이, 참외, 배추, 열무, 상추 총 13작물이며, 주산단지 선도농가 관비 사용량 조사 및 농가 실증시험을 통해 관비 표준량을 설정하였다. 작물별 관비 처방량은 흙토람(http://soil.rda.go.kr)에서 제공하고 있으며, 흙토람에서 작물별 재배시기, 기준 수량, 관수 방법, 비료 종류를 선택하면 관비(물+비료) 처방서를 발급할 수 있다. 관비 처방량과 농가의 물, 비료 사용량을 비교 했을 때, 물은 약 33%, 질소 비료는 약 41% 절감 가능한 것으로 나타났으며, 작물 수확 후 질산태질소 함량은 농가 관행에 비해 관비 처방서를 적용했을 때 감소한 것을 확인할 수 있었다. 따라서 관비처방서 활용을 통해 물과 비료의 이용효율을 높이고, 환경 영향도 최소화 할 수 있을 것으로 기대된다.
Kim, Sang‐,Young,Lee, Hyunseung,Kim, Hyun‐,Ju,Bang, Eunjung,Lee, Sung‐,Ho,Lee, Do‐,Wan,Woo, Dong‐,Cheol,Choi, Chi‐,Bong,Hong, Kwan Soo,Lee, Chulhyun,Choe, Bo‐ John Wiley Sons, Ltd 2011 NMR in biomedicine Vol.24 No.10
<P>Subanesthetic doses of ketamine, a noncompetitive <I>N</I>‐methyl‐<SMALL>D</SMALL>‐aspartate (NMDA) receptor antagonist, impair prefrontal cortex (PFC) function in the rat and produce symptoms in humans similar to those observed in patients with schizophrenia. In the present study, <I>in vivo</I> <SUP>1</SUP>H‐MRS and <I>ex vivo</I> <SUP>1</SUP>H high‐resolution magic angle spinning (HR‐MAS) spectroscopy was used to examine the brain metabolism of rats treated with subanesthetic doses of ketamine (30 mg/kg) for 6 days. A single voxel localization sequence (PRESS, TR/TE = 4000/20 ms and NEX = 512) was used to acquire the spectra in a 30‐µl voxel positioned in the cerebral cortex (including mainly PFC) of the rats (ketamine group: <I>n</I> = 12; saline group: <I>n</I> = 12) anesthetized with isoflurane. After the <I>in vivo</I> <SUP>1</SUP>H‐MRS acquisition, the animals were sacrificed and the cerebral cortex tissues were extracted (ketamine group: <I>n</I> = 7; saline group: <I>n</I> = 7) for <I>ex vivo</I> <SUP>1</SUP>H HR‐MAS spectroscopy (CPMG sequence, 2.0‐s presaturation delay, 2.0‐s acquisition time, 128 transients and 4‐ms inter‐pulse delay) using a 500‐MHz NMR spectrometer. All proton metabolites were quantified using the LCModel. For the <I>in vivo</I> spectra, there was a significant increase in glutamate concentration in the cerebral cortex of the ketamine group compared with the controls (<I>p</I> < 0.05). For the <I>ex vivo</I> HR‐MAS spectra, there was a significant increase in the glutamate/total creatine ratio, and a decrease in the glutamine/total creatine and glutamine/glutamate ratios in the cerebral cortex tissue of the ketamine group compared with the controls. The results of the present study demonstrated that administration of subanesthetic doses of ketamine in the rat may exert at least part of their effect in the cerebral cortex by activation of glutamatergic neurotransmission. Copyright © 2011 John Wiley & Sons, Ltd.</P>
Choi, Chi-Hoon,Yi, Kyung Sik,Lee, Sang-Rae,Lee, Youngjeon,Jeon, Chang-Yeop,Hwang, Jinwoo,Lee, Chulhyun,Choi, Sung Sik,Lee, Hong Jun,Cha, Sang-Hoon SAGE Publications 2018 Journal of cerebral blood flow and metabolism Vol.38 No.8
<P> To assess hyperacute focal cerebral ischemia in rats on 3.0-Tesla diffusion-weighted imaging (DWI), we developed a novel voxel-wise lesion segmentation technique that overcomes intra- and inter-subject variation in apparent diffusion coefficient (ADC) distribution. Our novel technique involves the following: (1) intensity normalization including determination of the optimal type of region of interest (ROI) and its intra- and inter-subject validation, (2) verification of focal cerebral ischemic lesions at 1 h with gross and high-magnification light microscopy of hematoxylin-eosin (H&E) pathology, (3) voxel-wise segmentation on ADC with various thresholds, and (4) calculation of dice indices (DIs) to compare focal cerebral ischemic lesions at 1 h defined by ADC and matching H&E pathology. The best coefficient of variation was the mode of the left hemisphere after normalization using whole left hemispheric ROI, which showed lower intra- (2.54 ± 0.72%) and inter-subject (2.67 ± 0.70%) values than the original. Focal ischemic lesion at 1 h after middle cerebral artery occlusion (MCAO) was confirmed on both gross and microscopic H&E pathology. The 83 relative threshold of normalized ADC showed the highest mean DI (DI = 0.820 ± 0.075). We could evaluate hyperacute ischemic lesions at 1 h more reliably on 3-Tesla DWI in rat brains. </P>