동형 모더나이트 상에서 일산화탄소 산화반응에 대한 속도론

정명수,이창용,최고열,하백현 漢陽大學校 環境科學硏究所 1989 環境科學論文集 Vol.10 No.-

모더나이트에 동을 이온교환 및 담지시킨 후 환원·산화 처리를 하여 동의 상태를 변화시킨 촉매에 대해 일산화탄소 산화반응의 속도론적인 고찰을 행하였다. 이온교환 촉매나 담지촉매 모두 동의 상태와는 관계없이 일산화탄소에 관한 반응차수는 1차이고 산소에 관한 반응차수는 0차였다. 이온교환 촉매의 경우는 수소로 환원시켜 동이 금속상태로 존재할때와 이를 재산화시켜 산화동 상태로 존재할때는 활성화에너지가 각각 16.4 및 20.3으로 비교적 큰 값을 나타냈으나 동의 담지촉매의 경우는 동이 금속일 때나 산화물 상태 모두 12∼13kcal/mole로 비슷한 값을 나타냈으며 이온교환 촉매보다 상당히 감소함을 알 수 있었다. 이와 같은 결과는 이온교환 촉매의 경우는 동이 제올라이트내부에 대부분 존재하는 반면, 담지촉매의 경우는 제올라이트 결정 표면에 존재하기 때문에 활성을 증가시키는 것으로 생각된다. Kinetics of oxidation of carbon monoxide over copper mordenite was carried out at the temperature range between 373K-443K in the micro-catalytic reactor. The experimental results indicated that the reaction order, with respect to carbon monoxide and oxygen was first and zero order respectively, regardless of the valence states such as copper metal, copper ion and copper oxide on the mordenite. The activation energy for metal-copper mordenite which is obtained by the ion-exchange revealed 20kcal/mol. But if this was reoxidized under the oxygen it decreased to 16.6kcal/mol. The activation energy of metal-copper mordenite which was obtained by impregnation and its reoxidized one under the oxygen were 12.2kcal/mol and 13.3kcal/mol respectively.

Weighing similarity against functionality to evaluate dung beetle species candidates for taxon substitution using an individual-based model

Jung-Wook Kho,Jung-Wook Kho,Joo-Young Kim,Do-Hun Gook,Hyunjoong Kim,Soowan Kim,Doo-Hyung Lee 한국응용곤충학회 2023 한국응용곤충학회 학술대회논문집 Vol.2023 No.04

Oral Medicine in Korea, Can We Become a Global Leader?

Kho, Hong-Seop Korean Academy of Orofacial Pain and Oral Medicine 2015 Journal of Oral Medicine and Pain Vol.40 No.1

Cryopreservation of Pointhead Flounder (Cleisthenes pinetorum herzensteini) Sperm

Kho, Kang Hee,Kang, Kyoung Ho 한국어류학회 2003 韓國魚類學會誌 Vol.15 No.4

용가지마 정자(Cleisthenes pinetorum herzensteini)를 액체질소를 이용하여 동결 보존하였고, 동결에 따른 정자의 운동성, 생존율 그리고 미세구조의 변화를 조사하였다. 정자의 운동성은 30% 인공해수(ASW)에서 운동성이 억제되었고, 100% 인공해수의 첨가에 의해 운동성이 개시되었다. 동해방지제로는 DMSO와 glycreol를 30% ASW에 최종농도가 5~20% 되도록 첨가하여 사용하였다. 그 결과 10% glycerol을 동해방지제로 하였을 때 정자의 운동성 및 생존율이 가장 높게 나타났으며 동결속도는 분당 20℃씨 - 80℃까지 내렸을 때 가장 보존효과가 높게 나타났다. 동결보존한 정자의 원형질막이 핵에서 분리되는 현상이 관찰되었다. In the present study, attempts were made to cryopreserve sperm of the pointhead flounder (Cleisthenespinetorum herzensteini) in liquid nitrogen to evaluate effects of various cryoprotectants and freezing rates on the motility and survival rate, and to identify the ultrastructural changes of sperm after cryopreservation. Sperm motility was significantly inhibited in 30% artificial seawater (ASW), but was restored entirely after 100% ASW was added again. Two cryoprotectants, dimethyl sulfoxide (DMSO) and glycerol, were added to 30% ASW to formulate the extenders at concentrations between 5% and 20% by volume for freezing. The highest post-thawed sperm motility and survival rate were obtained with 10% glycerol. Afterward, the effect of different freezing rates was examined using 10% glycerol as a cryoprotectant, and the rate of 20℃/min to -80℃ showed the best result. Ultrastructural changes of the detachment of plasma membranes were observed after cryopreservation.

The Reclamation of Body in Beloved

Kho, Younghee(고영희) 새한영어영문학회 2016 새한영어영문학 Vol.58 No.4

This paper explores the ways in which reclaiming body is central for former African American slaves to achieve their freedom from the haunting past of slavery in Toni Morrison’s Beloved. The subject of motherhood under slavery Morrison chose, in which mother-child relationship deteriorates into the possessive one of slavery, helps us see how serious and ongoing the problem of slavery is. When slave catchers find Sethe and her children, she attempts to kill all of them as if their bodies were owned by her, a consequence of her unconscious internalization of the slave owner’s logic. Morrison reveals the problem of such internalization through Beloved’s claim of her mother’s body. When she returns in the form of a young woman, Sethe becomes almost enslaved by Beloved and her insatiable demands. Their relationship soon degenerates into violence, testifying that they have not yet escaped out of their slaved past, a past thriving and waiting to overwhelm African American lives like “jungle” at any time. The real escape from the past comes when they acknowledge the necessary separation of their bodies. Only with such acknowledgement, Sethe is able to overcome the trauma of the past experiences and to recover from the fragmented body parts to the whole self.

MALDI-TOF MS Approach to Identify the E6AP-interacting factors in HeLa cervical cancer cells

Yoon DoYoung,Kho ChangWon,Lee Kyungae,Chung Yeongu,Park SungGoo,Park ByoungChul,Myung PyungKeun,Park SuenNie,Choe YongKyung 대한약학회 2002 大韓藥學會 總會 및 學術大會 Vol.2002 No.1

Administration of placenta-derived mesenchymal stem cells counteracts a delayed anergic state following a transient induction of endogenous neurogenesis activity after global cerebral ischemia

Kho, A Ra,Kim, Ok Joon,Jeong, Jeong Hyun,Yu, Ji Min,Kim, Hye Sun,Choi, Bo Young,Suh, Sang Won,Chung, Tae Nyoung Elsevier 2018 Brain Research Vol.1689 No.-

<P><B>Abstract</B></P> <P><B>Background</B></P> <P>Global cerebral ischemia (GCI) is a major obstacle for cardiac arrest survival. Recent studies have suggested the possibility of mesenchymal stem cell (MSC) as a novel therapeutic option for GCI, but these results were limited to the neuroprotective effects of MSCs. Therefore, we aimed to investigate specific characteristics of neurogenesis after transient GCI, and to assess the effect of MSC on these characteristics.</P> <P><B>Methods</B></P> <P>Adult male Sprague–Dawley rats were subjected to 7 min of transient GCI and randomized into 7 groups: baseline, MSC, and control administered groups, to be analyzed at 2, 3, and 4 weeks after GCI, respectively. The same interventions were repeated for sham operated animals. Rats were euthanized at the designated time after GCI.</P> <P><B>Results</B></P> <P>A comparison of GCI and sham groups without MSC treatment, showed that the counts of bromodeoxyuridine (BrdU)- and doublecortin (DCX)-positive cells were significantly increased in the GCI group at 1 week after insult, but the trend was reversed at 3 weeks after insult. The counts of BrdU-, Ki67- and DCX-positive cells and the intensity of zinc translocator 3 (ZnT3) were all significantly higher in the MSC-treated group than those in the control group at 3 weeks after GCI. The count of NeuN-positive cells in the hippocampus was significantly increased in the MSC group at 4 weeks after GCI.</P> <P><B>Conclusions</B></P> <P>GCI induces transient neurogenesis, followed by an anergic state. MSC may counteract this anergy of neurogenesis and result in an increase in intact neurons in later stages.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Neurogenesis increased after global cerebral ischemia but decreased soon. </LI> <LI> MSC administration counteracted the decrease of neurogenesis activity. </LI> <LI> Counteraction of MSC to anergy of neurogenesis resulted in more intact neurons. </LI> <LI> Effect of MSC on neurogenesis activity is consistent with ZnT3 expression. </LI> </UL> </P>

<i>Gastrodia elata</i> Ameliorates High-Fructose Diet-Induced Lipid Metabolism and Endothelial Dysfunction

Kho, Min Chul,Lee, Yun Jung,Cha, Jeong Dan,Choi, Kyung Min,Kang, Dae Gill,Lee, Ho Sub Hindawi Publishing Corporation 2014 Evidence-based Complementary and Alternative Medic Vol.2014 No.-

<P>Overconsumption of fructose results in dyslipidemia, hypertension, and impaired glucose tolerance, which have documented correlation with metabolic syndrome. <I>Gastrodia elata</I>, a widely used traditional herbal medicine, was reported with anti-inflammatory and antidiabetes activities. Thus, this study examined whether ethanol extract of <I>Gastrodia elata</I> Blume (EGB) attenuate lipid metabolism and endothelial dysfunction in a high-fructose (HF) diet animal model. Rats were fed the 65% HF diet with/without EGB 100 mg/kg/day for 8 weeks. Treatment with EGB significantly suppressed the increments of epididymal fat weight, blood pressure, plasma triglyceride, total cholesterol levels, and oral glucose tolerance, respectively. In addition, EGB markedly prevented increase of adipocyte size and hepatic accumulation of triglycerides. EGB ameliorated endothelial dysfunction by downregulation of endothelin-1 (ET-1) and adhesion molecules in the aorta. Moreover, EGB significantly recovered the impairment of vasorelaxation to acetylcholine and levels of endothelial nitric oxide synthase (eNOS) expression and induced markedly upregulation of phosphorylation AMP-activated protein kinase (AMPK)<I><I>α</I></I> in the liver, muscle, and fat. These results indicate that EGB ameliorates dyslipidemia, hypertension, and insulin resistance as well as impaired vascular endothelial function in HF diet rats. Taken together, EGB may be a beneficial therapeutic approach for metabolic syndrome.</P>

Effects of Protocatechuic Acid (PCA) on Global Cerebral Ischemia-Induced Hippocampal Neuronal Death

Kho, A Ra,Choi, Bo Young,Lee, Song Hee,Hong, Dae Ki,Lee, Sang Hwon,Jeong, Jeong Hyun,Park, Kyoung-Ha,Song, Hong Ki,Choi, Hui Chul,Suh, Sang Won MDPI 2018 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.19 No.5

<P>Global cerebral ischemia (GCI) is one of the main causes of hippocampal neuronal death. Ischemic damage can be rescued by early blood reperfusion. However, under some circumstances reperfusion itself can trigger a cell death process that is initiated by the reintroduction of blood, followed by the production of superoxide, a blood–brain barrier (BBB) disruption and microglial activation. Protocatechuic acid (PCA) is a major metabolite of the antioxidant polyphenols, which have been discovered in green tea. PCA has been shown to have antioxidant effects on healthy cells and anti-proliferative effects on tumor cells. To test whether PCA can prevent ischemia-induced hippocampal neuronal death, rats were injected with PCA (30 mg/kg/day) per oral (p.o) for one week after global ischemia. To evaluate degenerating neurons, oxidative stress, microglial activation and BBB disruption, we performed Fluoro-Jade B (FJB), 4-hydroxynonenal (4HNE), CD11b, GFAP and IgG staining. In the present study, we found that PCA significantly decreased degenerating neuronal cell death, oxidative stress, microglial activation, astrocyte activation and BBB disruption compared with the vehicle-treated group after ischemia. In addition, an ischemia-induced reduction in glutathione (GSH) concentration in hippocampal neurons was recovered by PCA administration. Therefore, the administration of PCA may be further investigated as a promising tool for decreasing hippocampal neuronal death after global cerebral ischemia.</P>

Isolation and Characterization of $\beta$-Hydroxybutyrate Dehydrogenase- deficient Mutant of Rhodobacter sphaeroides 2.4.1

Kho, Dohng-Hyo,Lee, Jeong-Kug The Korean Society for Microbiology and Biotechnol 1997 Journal of microbiology and biotechnology Vol.7 No.5

A transposon Tn5 mutant of Rhodobacter sphaeroides 2.4.1 was isolated for its impaired ability of growth on minimal medium containing ${\beta}$-hydroxybutyric acid as a sole carbon source. The mutant, R. sphaeroides S7 showed approximately 6-fold decrease in ${\beta}$-hydroxybutyrate dehydrogenase activity compared with that of wild type. In R. sphaeroides S7 the Tn5 was located in DNA region corresponding to a 4.2-kb EcoRI DNA fragment of R. sphaeroides 2.4.1 chromosome.