Effect of Mn and C on Age Hardening of Fe–Mn–Al–C Lightweight Steels

Sung‑Won Park,Jun Young Park,Kyong Mox Cho,Jae Hoon Jang,Seong‑Jun Park,Joonoh Moon,Tae‑Ho Lee,Jong‑Ho Shin 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.3

The effects of Mn and C content on the age hardening of Fe–Mn–Al–C lightweight steels, which have austenitic or duplex(austenite and ferrite) microstructures, were investigated. An increase in Mn content induced a delay of the age hardeningthat is caused by the formation of intra-granular κ-carbides. In order to interpret the effect of Mn content, first-principlescalculations were conducted using the supercells of Fe24Al8C8,Fe24Al8C7,Fe24(Al7Mn)C8, and Fe24(Al7Mn)C7. The calculationsshowed that an increase in Mn content could be the source of the delay of the intra-granular κ-carbide formation bysuppressing C atom’ occupation of the vacancy at the body-centered site of L12. An increase in C content accelerated theformation of intra-granular κ-carbides, which induced the intense age hardening, and coarse inter-granular κ-carbides, whichresulted in significant decrease in impact absorbed energy due to inter-granular fracture.

Skin entrance dose for digital and film radiography in Korean dental schools

Cho, Eun-Sang,Choi, Kun-Ho,Kim, Min-Gyu,Lim, Hoi-Jeong,Yoon, Suk-Ja,,Kang, Byung-Cheol 대한구강악안면방사선학회 2005 Imaging Science in Dentistry Vol.35 No.4

Purpose : This study was aimed to compare skin entrance dose of digital radiography with that of film radiography and to show the dose reduction achievement with digital systems at 11 dental schools in Korea. Materials and Methods : Forty six intraoral radiographic systems in 11 dental schools were included in this study. Digital sensors were used in 33 systems and film was used in 13 systems. Researchers and the volunteer visited 11 dental schools in Korea. Researchers asked the radiologic technician (s) at each school to set the exposure parameters and aiming the x-ray tube for the periapical view of the mandibular molar of the volunteer. The skin entrance doses were measured at the same exposure parameters and distance by the technician for each system with a dosimeter (Multi-O-Meter : Unfors instruments, Billdal, Sweden). Results : The median dose was 491.2 μGy for digital radiography and 1,205.0 μGy for film radiography. The skin entrance dose digital radiography was significantly lower than that of film radiography (p<0.05). Conclusion : Fifty-nine percent skin entrance dose reduction with digital periapical radiography was achieved over the film radiography in Korean dental schools.

제주 성상 S/S MTr #1 행원 풍력단지 전압해석

김상준(Sang-Jun Kim),조민호(Min-Ho Cho),윤기갑(Gi-Gab Yoon),장상옥(Sang-Ok Jang),안정식(Jeong-Shik Ahn) 대한전기학회 2003 대한전기학회 학술대회 논문집 Vol.2003 No.11

Antioxidant and hepatoprotective effects of Korean ginseng extract GS-KG9 in a D-galactosamine-induced liver damage animal model

Yun Ho Jo,Hwan Lee,Myeong Hwan Oh,Gyeong Hee Lee,You Jin Lee,Ji Sun Lee,Min Jung Kim,Won Yong Kim,Jin Seong Kim,Dae Seok Yoo,Sang Won Cho,Seon Woo Cha,Mi Kyung Pyo 한국영양학회 2020 Nutrition Research and Practice Vol.14 No.4

BACKGROUND/OBJECTIVES: This study was designed to investigate the improvement effect of white ginseng extract (GS-KG9) on D-galactosamine (Ga1N)-induced oxidative stress and liver injury. SUBJECTS/METHODS: Sixty Sprague-Dawley rats were divided into 6 groups. Rats were orally administrated with GS-KG9 (300, 500, or 700 mg/kg) or silymarin (25 mg/kg) for 2 weeks. The rats of the GS-KG9- and silymarin-treated groups and a control group were then intraperitoneally injected Ga1N at a concentration of 650 mg/kg for 4 days. To investigate the protective effect of GS-KG9 against GalN-induced liver injury, blood liver function indicators, anti-oxidative stress indicators, and histopathological features were analyzed. RESULTS: Serum biochemical analysis indicated that GS-KG9 ameliorated the elevation of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), and lactate dehydrogenase (LDH) in GalN-treated rats. The hepatoprotective effects of GS-KG9 involved enhancing components of the hepatic antioxidant defense system, including glutathione, glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase (CAT). In addition, GS-KG9 treatment inhibited reactive oxygen species (ROS) production induced by GalN treatment in hepatocytes and significantly increased the expression levels of nuclear factor erythroid-2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) proteins, which are antioxidant proteins. In particular, by histological analyses bases on hematoxylin and eosin, Masson"s trichrome, α-smooth muscle actin, and transforming growth factor-β1 staining, we determined that the administration of 500 mg/kg GS-KG9 inhibited hepatic inflammation and fibrosis due to the excessive accumulation of collagen. CONCLUSIONS: These findings demonstrate that GS-KG9 improves GalN-induced liver inflammation, necrosis, and fibrosis by attenuating oxidative stress. Therefore, GS-KG9 may be considered a useful candidate in the development of a natural preventive agent against liver injury.

Synergistic Renoprotective Effect of Melatonin and Zileuton by Inhibition of Ferroptosis via the AKT/mTOR/NRF2 Signaling in Kidney Injury and Fibrosis

Jung Kyung Hee,Kim Sang Eun,Go Han Gyeol,Lee Yun Ji,Park Min Seok,Ko Soyeon,Han Beom Seok,Yoon Young-Chan,Cho Ye Jin,Lee Pureunchowon,Lee Sang-Ho,Kim Kipyo,Hong Soon-Sun 한국응용약물학회 2023 Biomolecules & Therapeutics(구 응용약물학회지) Vol.31 No.6

According to recent evidence, ferroptosis is a major cell death mechanism in the pathogenesis of kidney injury and fibrosis. Despite the renoprotective effects of classical ferroptosis inhibitors, therapeutic approaches targeting kidney ferroptosis remain limited. In this study, we assessed the renoprotective effects of melatonin and zileuton as a novel therapeutic strategy against ferroptosis-mediated kidney injury and fibrosis. First, we identified RSL3-induced ferroptosis in renal tubular epithelial HK-2 and HKC-8 cells. Lipid peroxidation and cell death induced by RSL3 were synergistically mitigated by the combination of melatonin and zileuton. Combination treatment significantly downregulated the expression of ferroptosis-associated proteins, 4-HNE and HO-1, and upregulated the expression of GPX4. The expression levels of p-AKT and p-mTOR also increased, in addition to that of NRF2 in renal tubular epithelial cells. When melatonin (20 mg/kg) and zileuton (20 mg/kg) were administered to a unilateral ureteral obstruction (UUO) mouse model, the combination significantly reduced tubular injury and fibrosis by decreasing the expression of profibrotic markers, such as α-SMA and fibronectin. More importantly, the combination ameliorated the increase in 4-HNE levels and decreased GPX4 expression in UUO mice. Overall, the combination of melatonin and zileuton was found to effectively ameliorate ferroptosis-related kidney injury by upregulating the AKT/mTOR/ NRF2 signaling pathway, suggesting a promising therapeutic strategy for protection against ferroptosis-mediated kidney injury and fibrosis.

종 분포 모형을 이용한 구상나무림의 지속 및 쇠퇴에 관한 연구 - 전라남도 광양시 백운산을 중심으로 -

조선희 ( Seon Hee Cho ),박종영 ( Jong Young Park ),박정호 ( Jeong Ho Park ),이양근 ( Yang Geun Lee ),문이만 ( Lee Man Mun ),강상호 ( Sang Ho Kang ),김광현 ( Gwang Hyun Kim ),윤종국 ( Jong Guk Yun ) 한국산림과학회 2015 한국산림과학회지 Vol.104 No.3

The present study investigated the habitats of Korean fir trees (Abies koreana E. H. Wilson) on Mt. Baekwun (Baekwun-san), determined the current distribution, quantified the contribution of biological and nonbiological environmental factors affecting the distribution, derived actual and potential habitats, presented a plan for the establishment of protected areas, applied RCP 8.5 climate change scenario to analyze the effects of climate change on the future distribution of Korean fir trees, and predicted future potential habitats. According to the results of the study, 3,325 Korean fir trees (DBH >= 2.5 cm) inhabited Mt. Baekwun, and their distribution area was approximately 150 ha. Populations of Korean fir trees were confirmed to exist at an altitude of 900 m above sea level and were distributed up to 1,200 m. Based on potential distribution, areas appropriate for habitation by Korean fir trees were analyzed to be 450 ha, three times the current distribution area, with a focus on Sang Peak (Sang-bong), Eokbul Peak (Eokbul-bong), Ddari Peak (Ddari-bong), and Dosol Peak (Dosol-bong). The forest stands near Sang Peak, the main peak, were evaluated as those with the most appropriate potential for the habitation of Korean fir trees, and populations of the trees tended to prefer the northern slope rather than the southern slope. When climate change scenario RCP 8.5 was applied and future potential distribution was analyzed, the habitats were expected to decrease in area to 20 ha by 2050, with a focus on Sang Peak, and areas appropriate for habitation were predicted not to exist by 2080. Judging from such results, as global warming accelerates, the habitats of Korean fir trees are clearly expected to move from lowlands to highlands.

Adenovirus-mediated heme oxygenase-1 gene transfer to neonatal porcine islet-like cluster cells: the effects on gene expression and protection from cell stress

염혜정,Han Ro,Sol Ji Park,Ju Ho Hong,Bumrae Cho,김화정,Sung Joo Kim,황종익,이병천,안규리,양재석 한국바이오칩학회 2012 BioChip Journal Vol.6 No.1

Porcine islet xenotransplantation is a promising strategy for the treatment of diabetes that overcomes donor shortages. However, islet xenografts are susceptible to oxidative stress and apoptosis. Heme oxygenase-1 (HO-1) has been shown to protect cells from oxidative stress, apoptosis and inflammation. Here, we investigated whether introduction of human HO-1 (hHO-1) into neonatal porcine islet-like cell clusters (NPCCs) can induce beneficial transcriptional changes in NPCCs against cellular stress. NPCCs were transduced with either adenovirus-HO-1 (Ad-HO-1) or control adenovirus-GFP (Ad-GFP). After treatment with hydrogen peroxide (H2O2) for 24 hours, nitrite oxide (NO) production assays were performed to detect oxidative stress. Microarray analysis was performed using a pig oligonucleotide 44 K gene chip. We profiled transcriptional changes to apoptosis, oxidant and inflammatory genes, and real-time PCR analysis was also performed to confirm the microarray results. Survival of NPCCs after treatment with H2O2 was significantly higher in the Ad-HO-1 group (p⁄0.001), and NO production also decreased in the Ad-HO-1 group (p⁄0.01). The microarray results showed that the expression of pro-apoptosis genes such as CASP3, CASP7, CASP10, CIDE-B and CIDE-C was significantly decreased in the Ad-HO-1 virus group (CASP10; p⁄0.05, CASP3, CIDE-C; p⁄0.01, CASP7, CIDE-B; p⁄0.001). We also found that the expression of oxidative stresses genes including COX1, COX2, CYB5A, SDHD and NOS2 was decreased, and that the anti-oxidant genes Gpx1 and SOD2 were increased in the Ad-HO-1 group (NOS2; p⁄0.05, COXI, COX2, CYB5A, SDHD, SOD2, GPX1; p⁄0.001). However, inflammatory gene expression was not significantly changed. Realtime PCR analysis confirmed the results of the microarray analysis. These results shed light on the underlying mechanisms of the protective effects of hHO-1 on porcine islets from cellular stresses and suggest that hHO-1 could be a promising target gene for the production of transgenic pigs that confer improved islet xenograft survival.

H₂O₂로 산화적 스트레스가 유도된 각질 형성 세포에서 흑삼 추출물의 항노화 효과

안소희(So Hee Ahn),이계원(Gye Won Lee),권득상(Deuk Sang Kwon),신현중(Hyun Joong Shin),조영호(Young Ho Cho) 한국식품영양과학회 2021 한국식품영양과학회지 Vol.50 No.10

본 연구에서는 95°C에서 6번 증숙하여 제조한 흑삼 추출물의 항산화 활성과 피부세포에서 산화적 스트레스로부터 보호 효과를 확인하고, 항산화 효소 발현, 주름개선 및 보습관련 단백질 발현에 미치는 영향을 측정하였다. 흑삼 추출물(BGE-A6)의 항산화 활성을 평가하기 위하여 DPPH, ABTS, superoxide anion 라디칼 소거 활성 및 환원력을 측정하였다. 그 결과 증숙 후 흑삼 추출물이 증숙 전에 비하여 DPPH 라디칼 소거 활성은 4배, ABTS 라디칼 소거 활성은 5배 정도 항산화 활성이 증가하는 것으로 나타났다. 피부 각질 형성 세포에서 산화적 스트레스로부터 BGE-A6의 세포보호 효과를 측정하기 위하여 BGE-A6를 1시간 전처리하고 0.5 mM H₂O₂를 6시간 동안 처리하여 분석한 결과, H₂O₂ 처리로 증가된 ROS 생성이 BGE-A6를 100 μg/mL 농도로 처리한 경우 약 40% 정도 감소되는 것으로 나타났다. 또한, BGE-A6의 ROS 소거 효과를 규명하기 위하여 세포 내 존재하는 항산화 효소의 발현량을 western blot으로 평가한 결과 H₂O₂에 의해 유도된 산화 스트레스로부터 감소된 항산화 효소(HO-1, CAT, SOD)의 발현을 농도 의존적으로 회복시켰다. 또한, BGE-A6의 주름 개선 효과를 확인하기 위하여 콜라겐 발현 및 MMP-1 발현 억제 정도를 ELISA와 western blot으로 측정한 결과 0.5 mM H₂O₂를 처리하였을 때 감소된 콜라겐 생성량이 BGE-A6를 100 μg/mL 농도로 처리할 경우 H₂O₂ 처리에 의해 감소된 콜라겐 생성량을 약 20% 정도 회복시키는 것으로 확인되었다(P<0.05). 0.5 mM H₂O₂를 처리하였을 때 증가된 MMP-1의 생성이 BGE-A6 처리 시 농도 의존적으로 억제되는 것으로 나타났다. BGE-A6의 피부보습 관련 단백질 발현에 미치는 영향을 western blot으로 측정한 결과 HAS2와 AQP3 발현량 및 EGFR의 인산화를 처리 시 농도 의존적으로 증가시키는 것으로 나타났다. 결론적으로 피부세포에 H₂O₂를 처리하여 산화적 스트레스를 유도하였을 때 BGE-A6는 항산화 효소의 발현을 통해 세포보호 효과를 나타내고, AQP3, HAS2 및 콜라겐 단백질의 발현은 증가시키고 MMP-1의 발현을 감소시켜 피부보습 및 피부장벽 기능을 유지하는 것으로 사료된다. 또한, AQP3의 증가는 피부조직 및 피부세포막에 발현되는 EGF 수용체의 인산화를 증가시킴으로써 피부 건조에 대한 보호 효과도 있는 것으로 판단된다. 따라서 흑삼 추출물은 항산화 효과, 피부보습 및 장벽기능 유지를 통한 항노화 화장품 소재로 활용이 가능할 것으로 기대된다. In this study, black ginseng extract steamed six times at 95°C (BGE-A6) was evaluated for its antioxidant, anti-wrinkle, and skin moisturizing effects in human keratinocytes. When steamed six times at 95°C, the content of total ginsenosides including minor ginsenosides (Rg3, Rh4, Rk1, and Rg5) was the highest at 14.97 mg/g. The antioxidant properties of BGE-A6 were measured by using different in vitro antioxidant assays such as 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid, ABTS), and superoxide anion radical scavenging activity. The antioxidant activity of BGE-A6 was increased in a dose-dependent manner. A 2′,7′-dichlorofluorescin diacetate (DCFDA) assay and a western blot assay were performed to verify the reactive oxygen species (ROS) scavenging activity of BGE-A6 in H₂O₂-induced human keratinocytes. Pretreatment with 100 μg/mL of BGE-A6 inhibited intracellular ROS production by about 40%. Also, the expression of heme oxygenase-1 (HO-1), catalase (CAT), and superoxide dismutase-1 (SOD-1), very well-known as antioxidant enzymes, was increased by BGE-A6 in a dose-dependent manner. BGE-A6 was shown to significantly inhibit the expression of matrix metalloproteinase-1 and increase the production of type I collagen, thus confirming its anti-wrinkle activity (P<0.05). Furthermore, BGE-A6 significantly increased the phosphorylation of the epidermal growth factor receptors (EGFR) and the expression of moisturizing proteins, such as hyaluronic acid synthase 2 (HAS2) and aquaporin 3 (AQP3), indicating that it is effective in enhancing skin hydration. The results of this study suggest that BGE-A6 has potential for use as an effective compound in anti-aging cosmetics to address wrinkle formation and skin hydration.

Implication of necrosis-linked p53 aggregation in acquired apoptotic resistance to 5-FU in MCF-7 multicellular tumour spheroids

Lee, Su Yeon,Jeong, Eui-Kyong,Jeon, Hyun Min,Kim, Cho Hee,Kang, Ho Sung Spandidos Publications 2010 Oncology reports Vol.24 No.1

<P>Three-dimensional (3D) multicellular tumour spheroids (MTS) have been used as an in vitro model of solid tumours for drug resistance studies because they mimic the growth characteristics of in vivo tumours more closely than in vitro two-dimensional (2D) culture of cancer cell lines. As observed in solid tumours, MTS exhibits a proliferation gradient with outer regions consisting of proliferating cells that surround inner quiescent cells. The innermost cells in core regions undergo cell death mostly by necrosis to form necrotic core due to insufficient supply of oxygen and nutrient such as glucose with increasing size of spheroids. Tumour necrosis is thought to indicate a poor prognosis and to contribute to acquisition of chemoresistance in solid tumours; however, the mechanism underlying necrosis-mediated chemoresistance remains unclear. In this study, we examined the chemoresistance to 5-Fluorouracil (5-FU) using MCF-7 breast cancer MTS. 5-FU (400 microM) induced apoptosis in MCF-7 cell monolayer as determined by HO/PI staining, PARP cleavage, p53 induction, Bax induction, and Bcl-2 down-regulation. When MCF-7 breast tumour spheroids were cultured on agarose for 8 days, they reached approximately 700 microm in diameter, with a necrotic core. We found that 5-FU-induced apoptosis is markedly reduced in spheroids that were cultured for 9 days and had necrotic core, compared with MCF-7 monolayer cells and spheroids that were cultured for 6 days and had no necrotic core, indicating that the formation of necrotic core may be linked to acquisition of chemoresistance to 5-FU. We also found that a specific set of cellular proteins including p53 was aggregated into a RIPA-insoluble form during MTS culture. Furthermore, most of p53 induced by 5-FU was aggregated in MTS with necrotic core. Our results suggest that necrosis-linked p53 aggregation may contribute to acquired apoptotic resistance to 5-FU in MTS model system.</P>

소아에서 간질발작의 임상양상과 뇌파검사의 관계

이승현(Seung Hyeon Lee),손동우(Dong Woo Son),은병욱(Byung Wook Eun),심소연(So Yeon Sim),최덕영(Deok Young Choi),선용한(Yong Han Sun),조강호(Kang Ho Cho0, 류 일(Eell Ryoo),전인상(In Sang Jeon0, 차 한(Hann Tchah) 대한소아신경학회 2009 대한소아신경학회지 Vol.17 No.2

목적:발작의 분류는 발작의 원인, 예후를 추정하거나 항경련제를 선택하는 데 있어 매우 중요하며 뇌파검사는 발작의 종류를 구분하고 적절한 치료를 하기 위해 시행하는 중요한 검사이다. 저자들은 소아에서 임상적 발작이 확실한 경우 간질발작의 임상양상과 뇌파검사 간의 일치 정도를 알아보고자 한다. 방법:2000년 1월 1일부터 2008년 9월 30일까지 1회 이상의 간질발작을 주소로 가천의대 길병원 소아청소년과에 방문한 환자 중 본원에서 처음으로 뇌파검사를 시행한 환자를 대상으로 하였다. 발작의 임상양상은 목격자와 본인의 설명을 기록한 의무기록지를 기준으로 하여 부분발작과 전신발작으로 분류하였고 뇌파검사는 발작간간질양방전을 기준으로 정상과 비정상으로 분류하였으며 각성과 수면상태 모두에서 시행하였다. 결과:총 461명의 환자의 뇌파검사 시의 평균 연령은 6.7세였고 남자는 247명, 여자는 214명이었다. 전체 환자에서 발작의 임상양상은 부분발작이 310명, 전신발작이 187명이었다. 각성뇌파검사에서 비정상은 158명으로 부분발작파가 118명, 전신발작파가 59명, 두 가지 발작파가 한 환자에서 나온 경우가 19명이었고, 수면뇌파검사에서는 비정상이 239명으로 부분발작파가 196명, 전신발작파가 77명, 두 가지 발작파가 한 환자에서 나온 경우가 34명이었으며 전체 환자에서는 비정상이 273명으로 부분발작파가 216명, 전신발작파가 97명, 두 가지 발작파가 한 환자에서 나온 경우가 40명이었다. 간질증후군은 전체 환자 중 90명에서 관찰되었다. 146명(41.5%)의 부분발작과 44명(23.4%)의 전신발작 및 79명(87.8 %)의 간질증후군이 뇌파소견과 일치하였다. 결론:영유아 및 소아에 있어 발작을 진단할 때에는 발작양상 분 아니라 정확한 뇌파소견을 세심하게 고려하여야 한다. Purpose:Electroencephalography(EEG) is an essential method carried out for classifying seizures and taking appropriate treatment. The aim of this study is to investigate the concordance between clinical findings of epileptic seizures and EEG in children. Methods:We enrolled 461 patients from those who visited Gil hospital from January 1, 2000 to September 30, 2008 with the chief complaint of epileptic seizure more than once and checked their first EEG at the same hospital. The clinical findings of seizure were based on the charts and interictal waking and sleep EEGs were done. Results:The mean age of the patients was 6.7 years old. 497 epileptic seizures occurred and its clinical finding included 310 of partial seizures and 187 of generalized seizures. In 315 waking EEG 158 were abnormal including 118 of partial seizures, 59 of generalized seizures and 19 of both seizures, in 431 sleep EEG 239 were abnormal including 196 of partial seizures, 77 of generalized seizures and 34 of both seizures, and in waking and/or sleep EEG 273 were abnormal including 216 of partial seizures, 97 of generalized seizures and 40 of both seizures. Epileptic syndromes were observed in 90 patients. 146(41.5%) of partial seizures, 44(23.4%) of generalized seizures, and 79(87.8%) of epileptic syndromes accorded with EEG. Conclusion:When diagnosing seizures in children, we must consider not only clinical findings but also accurate EEG findings.