Yonsei University

About: Yonsei University is a education organization based out in Seoul, South Korea. It is known for research contribution in the topics: Population & Cancer. The organization has 50162 authors who have published 106172 publications receiving 2279044 citations. The organization is also known as: Yonsei.

Two distinct mechanisms are involved in 6-hydroxydopamine- and MPP+- induced dopaminergic neuronal cell death: Role of caspases, ROS, and JNK

Abstract: In this study, we examined the possibility that MPTP and 6-hydroxydopamine (6-OHDA) act on distinct cell death pathways in a murine dopaminergic neuronal cell line, MN9D. First, we found that cells treated with 6-OHDA accompanied ultrastructural changes typical of apoptosis, whereas MPP+ treatment induced necrotic manifestations. Proteolytic cleavage of poly(ADP-ribose)polymerase by caspase was induced by 6-OHDA, whereas it remained uncleaved up to 32 h after MPP+ treatment and subsequently disappeared. Accordingly, 6-OHDA- but not MPP+-induced cell death was significantly attenuated in the presence of a broad-spectrum caspase inhibitor, N-benzyloxy-carbonyl-Val-Ala-Asp-fluomethylketone (Z-VAD-fmk). As measured by fluorometric probes, the level of reactive oxygen species (ROS) significantly increased after 6-OHDA treatment. In contrast, the level of dihydroethidium-sensitive ROS following MPP+ treatment remained unchanged while a slight increase in dichlorofluorescin-sentive ROS was temporarily observed. As demonstrated by immunoblot analysis, the level of superoxide dismutase was down-regulated following 6-OHDA treatment, whereas it remained unchanged after MPP+ treatment. Cotreatment of cells with antioxidants such as N-acetylcysteine or Mn(III)tetrakis(4-benzoic acid)porphyrin chloride (MnTBAP, cell-permeable superoxide dismutase mimetic) rescued 6-OHDA- but not MPP+-induced cell death, whereas inclusion of catalase or NG-nitro-l-arginine had no effect in both cases. In addition, 6-OHDA induced ROS-mediated c-Jun N-terminal kinase (JNK) activation that was attenuated in the presence of N-acetylcysteine or MnTBAP but not catalase or Z-VAD-fmk. In contrast, MPP+ has little effect on JNK activity, indicating that ROS and/or ROS-induced cell death signaling pathway seems to play an essential role in 6-OHDA–mediated apoptosis but not in MPP+-induced necrosis in a mesencephalon-derived, dopaminergic neuronal cell line. J. Neurosci. Res. 57:86–94, 1999. © 1999 Wiley-Liss, Inc.

Fighting COVID-19 with Agility, Transparency, and Participation: Wicked Policy Problems and New Governance Challenges.

Abstract: Governments are being put to the test as they struggle with the fast and wide spread of COVID-19. This article discusses the compelling challenges posed by the COVID-19 pandemic by examining how this wicked problem has been managed by the South Korean government with agile-adaptive, transparent actions to mitigate the surge of COVID-19. Unlike many Western countries, South Korea has been able to contain the spread of COVID-19 without a harsh forced lockdown of the epicenter of the virus. This essay argues that an agile-adaptive approach, a policy of transparency in communicating risk, and citizens' voluntary cooperation are critical factors. It also suggests that the South Korean government learned costly lessons from the MERS failure of 2015. This essay suggests ways that Western countries can manage future wicked problems such as COVID-19 without paying too much cost and maintaining quality of life in open and free societies.