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Lee, Joo-Yong,Kapur, Meghan,Li, Ming,Choi, Moon-Chang,Choi, Sujin,Kim, Hak-June,Kim, Inhye,Lee, Eunji,Taylor, J. Paul,Yao, Tso-Pang The Company of Biologists Ltd. 2014 Journal of cell science Vol.127 No.22
<P>Fasting and glucose shortage activate a metabolic switch that shifts more energy production to mitochondria. This metabolic adaptation ensures energy supply, but also elevates the risk of mitochondrial oxidative damage. Here, we present evidence that metabolically challenged mitochondria undergo active fusion to suppress oxidative stress. In response to glucose starvation, mitofusin 1 (MFN1) becomes associated with the protein deacetylase HDAC6. This interaction leads to MFN1 deacetylation and activation, promoting mitochondrial fusion. Deficiency in HDAC6 or MFN1 prevents mitochondrial fusion induced by glucose deprivation. Unexpectedly, failure to undergo fusion does not acutely affect mitochondrial adaptive energy production; instead, it causes excessive production of mitochondrial reactive oxygen species and oxidative damage, a defect suppressed by an acetylation-resistant MFN1 mutant. In mice subjected to fasting, skeletal muscle mitochondria undergo dramatic fusion. Remarkably, fasting-induced mitochondrial fusion is abrogated in HDAC6-knockout mice, resulting in extensive mitochondrial degeneration. These findings show that adaptive mitochondrial fusion protects metabolically challenged mitochondria.</P>
A Mn(iv)-peroxo complex in the reactions with proton donors
Lee, Chien-Ming,Sankaralingam, Muniyandi,Chuo, Chi-He,Tseng, Tzu-Hsien,Chen, Peter P.-Y.,Chiang, Ming-Hsi,Li, Xiao-Xi,Lee, Yong-Min,Nam, Wonwoo The Royal Society of Chemistry 2019 Dalton Transactions Vol.48 No.16
<P>Protons play an important role in promoting O-O or M-O bond cleavage of metal-peroxo complexes. Treatment of side-on O2-bound [PPN][Mn<SUP>IV</SUP>(<SUP>TMS</SUP>PS3)(O2)] (1, PPN = bis(triphenylphosphine)iminium and <SUP>TMS</SUP>PS3H3 = 2,2′,2′′-trimercapto-3,3′,3′′-tris(trimethylsilyl)triphenylphosphine) with perchloric acid (HClO4) in the presence of PR3 (R = phenyl or <I>p</I>-tolyl) results in the formation of neutral five-coordinate Mn<SUP>III</SUP>(OPR3)(<SUP>TMS</SUP>PS3) complexes (R = phenyl, 2a; <I>p</I>-tolyl, 2b), which are confirmed by X-ray crystallography. Isotope labelling experiments demonstrate that the oxygen atom in the phosphine oxide product derives from the peroxo ligand of 1. Reactions of 1 with weak proton donors, such as phenylthiol, phenol, substituted phenol and methanol, are also investigated to explore the reactivity of the Mn<SUP>IV</SUP>-peroxo complex, leading to the isolation of a series of five-coordinate [Mn<SUP>III</SUP>(L)(<SUP>TMS</SUP>PS3)]<SUP>−</SUP> complexes (L = phenylthiolate, phenolate or methoxide). Mechanistic aspects of the reactions of the Mn<SUP>IV</SUP>-peroxo complex with proton donors are discussed as well.</P>
Yong-Ming Lee,Disney R. Henry L.,Raja M. Zuha 한국응용곤충학회 2021 Journal of Asia-Pacific Entomology Vol.24 No.3
Megaselia spiracularis Schmitz (Diptera: Phoridae) is a scuttle fly species of forensic importance and has been recorded colonizing human corpses in Malaysia, Korea and China. The necrophagous activity of M. spiracularis larvae on human corpses can be referred to estimate minimum postmortem interval (PMI min ) in death investi gation. However, developmental data of M. spiracularis derived from ambient fluctuating temperature is scarce and taxonomic descriptions to larval instars for species identification are still lacking. This research was con ducted to address these limitations by studying the development of M. spiracularis at fluctuating ambient tem peratures. From each sampling occasion, larval body lengths were obtained and samples were mounted on slides to determine larval instars based on taxonomic characteristics of the cephalopharyngeal skeleton, anterior spi racles and posterior spiracles. At fluctuating temperatures of 25–37 ◦ C and relative humidity of 47–93%, developmental duration of egg stage was 7–9.5 h; first instar larva, 9.5–17 h; second instar, 6–12 h, feeding third instar, 18–36 h; post-feeding third instar, 6–12 h; and pupa, 168–204 h. Accumulated degree hours for each developmental stage based on fluctuating ambient temperatures were also determined. The size of M. spiracularis larvae varied from 0.64–0.78 mm after eclosion to 5.20–5.95 mm before entering post feeding phase. The first, second and third instar larva could be distinguished mainly by the morphology of cephalopharyngeal skeletons, anterior spiracles and posterior spiracles. Developmental durations of M. spiracularis larvae and the larval instars can be used as references to estimate PMI min as this species is likely to be featured in future forensic cases.
이용운(Yong-Woon Lee),예인수(In-Soo Ye),이명일(Ming-Ri Li),홍재현(Jae-Hyeon Hong),오정근(Jeong-Geun Oh),이웅진(Ung-Jin Lee),류창국(Chang-Kook Ryu) 한국연소학회 2010 KOSCOSYMPOSIUM논문집 Vol.- No.40
Wood pellet is a densified fuel with homogeneous physical properties suitable for use in various scales of domestic and industrial furnaces. A wood pellet stove is a small-scale furnace for domestic heat production, which can replace the conventional oil or gas boilers. Since the fuel properties of wood pellet is very different from oil or gas, the design of a wood pellet stove requires profound understanding on the solid fuel combustion as well as gas flow mixing/reactions. Due to the size limit of the furnace height (~1m) for domestic installation, poor design of furnace, air supply and heat exchanger may lead to excessive emission of CO or low energy efficiencies. This study evaluated the design of an existing wood pellet stove with 30,000 ㎉/hr capacity using experimental and computational techniques in order to optimize the furnace design. The results show that it is critical to minimize the unused furnace volume and to enhance the gaseous mixing for reduced CO emission.
Prodisc Artificial Disc Replacement
Wen-Ming Chen,Hui-Sung Lee,Kwon-Yong Lee,Chun-Kun Park,Sung-Jae Lee 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
The artificial disc replacement (ADR) technique for the lumbar spine, with the “joint motion preservation” concept, aims to replicate the natural disc dynamics and load transfer through the lumbar motion segments. However, ADR designs vary greatly in their approaches to restore the normal disc function. In this study, Prodisc II, a most-widely used ADR type in Korea, was chosen. A validated three-dimensional intact osteoligamentous L2-L4 FE model was modified to simulate the ADR by Prodisc II, via anterior approach at L3-L4 level. The models were loaded with a combination of compressive preload 400N and 10Nm flexion/extension moments. The lumbar range of motion and facet loads, contact area (CAREA) and total contact forces (TCF) across the implant articulation surfaces was evaluated. We found that the flexion motions across surgical level L3-L4 and its adjacent level L2-L3 remain unchanged. In extension, at surgical level, the Prodisc model had a 91.4% increase and L2-L3 a decrease of 6.8%. The facet loads through L3-L4 increased by 33.2% in flexion and 36.3% in extension. CAREA/TCF was 41.47㎜2/723N for flexion and 11.68㎜2/324.6N for extension. The major CAREA was located posteriorly in extension and more evenly distributed in flexion. The lumbar segment mobility in flexion was retained after Prodisc replacement, but extension motion at the surgical level became more flexible and more stresses was imposed to the facet joint. The CAREA/TCF can be used as an indicator for the prediction of the wearing properties of the Prodisc in clinical service.
Chen Wen-Ming,Ahn Yoon-Ho(안윤호),Lee Hui-Sung(이희성),Moon Soo-Jung(문수정),Lee Kwon-Yong(이권용),Lee Sung-Jae(이성재) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11
The endplate that lies between the vertebral body and intervertebral disc is a structure of significant physiological importance. However, mechanically the end-plate appears to be a “weak link” and its fracture pattern presents an age-related phenomenon. In current study, the effects of simulated degenerative changes in the lumbar disc and vertebral body on the endplate were examined using finite element (FE) analysis. For this purpose, an intact lumbar functional spinal unit (FSU) of L3-4 FE model was constructed and another three degenerative models were made by modifying the intact one. A mildly degenerated disc was simulated by removing the hydrostatic capacities of the nucleus and making the disc stiffer than a normal one. The severe degenerated disc, made by “nuclotomy”, was assumed to be void of nucleus. The possible alterations in bone quality due to osteoporosis were simulated by adjusting the corresponding material properties of bony structures. Under axial compression of 2000N, compared to the intact case, the model with “stiffer” disc showed an 82.4% decrease in tensile stress in posterior region, a 22.5% increase in compression in the mid region of the endplate respectively; while compressive stress generated anteriorly. The “nucleotomy” case showed reversed stress states in all regions of the endplate correspondingly. As to the “osteoporosis” model, there were 32% and 50.6% increases in the tensile stress in posterior and anterior regions of the endplate respectively. Based on these results, the failure patterns could be predicted. We concluded that the stress and strain distributions in endplate under axial loading were highly dominated by its adjacent structures. Both the degenerated disc and osteoporosis may have a pronounced impact on the structural failure of the endplate, and the possible fracture patterns predicted by FE model might be used as references for the clinical assessment of the failure mechanism of the endplate.