On‐Nanowire Band‐Graded Si:Ge Photodetectors

Kim, Cheol&#x2010,Joo,Lee, Hyun&#x2010,Seung,Cho, Yong&#x2010,Jun,Yang, Jee&#x2010,Eun,Lee, Ru Ri,Lee, Ja Kyung,Jo, Moon&#x2010,Ho WILEY‐VCH Verlag 2011 Advanced Materials Vol.23 No.8

<P><B>An on‐nanowire (on‐NW) band‐graded photodetector that pertains to the on‐nanowire composition gradation from pure Si to pure Ge</B>, Si<SUB>1–<I>x</I></SUB>Ge<SUB><I>x</I></SUB> (0 ≤ <I>x</I> ≤ 1), is reported. The spectral onset of interband photocarrier generation and photocurrent amplitude are on‐NW de‐multiflexed over the continuously varying energy band gap and surface trap state density in an individually addressable manner. </P>

Zinc‐triggered induction of tissue plasminogen activator by brain‐derived neurotrophic factor and metalloproteinases

Hwang, Ih&#x2010,Yeon,Sun, Eun&#x2010,Sun,An, Ji Hak,Im, Hana,Lee, Sun&#x2010,Ho,Lee, Joo&#x2010,Yong,Han, Pyung&#x2010,Lim,Koh, Jae&#x2010,Young,Kim, Yang‐,Hee Blackwell Publishing Ltd 2011 Journal of Neurochemistry Vol.118 No.5

<P> <I>J. Neurochem.</I> (2011) <B>118</B>, 855–863.</P><P><B>Abstract</B></P><P>Tissue plasminogen activator (tPA) is necessary for hippocampal long‐term potentiation. Synaptically released zinc also contributes to long‐term potentiation, especially in the hippocampal CA3 region. Using cortical cultures, we examined whether zinc increased the concentration and/or activity of tPA. Two hours after a 10‐min exposure to 300 μM zinc, expression of tPA and its substrate, plasminogen, were significantly increased, as was the proteolytic activity of tPA. In contrast, increasing extracellular or intracellular calcium levels did not affect the expression or secretion of tPA. Changing zinc influx or chelating intracellular zinc also failed to alter tPA/plasminogen induction by zinc, indicating that zinc acts extracellularly. Zinc‐mediated extracellular activation of matrix metalloproteinase (MMP) underlies the up‐regulation of brain‐derived neurotrophic factor (BDNF) and tropomyosin receptor kinase (Trk) signaling. Consistent with these findings, co‐treatment with a neutralizing antibody against BDNF or specific inhibitors of MMPs or Trk largely reversed tPA/plasminogen induction by zinc. Treatment of cortical cultures with <I>p</I>‐aminophenylmercuric acetate, an MMP activator, MMP‐2, or BDNF alone induced tPA/plasminogen expression. BDNF mRNA and protein expression was also increased by zinc and mediated by MMPs. Thus, an extracellular zinc‐dependent, MMP‐ and BDNF‐mediated synaptic mechanism may regulate the levels and activity of tPA.</P>

3′‐Sialyllactose protects against osteoarthritic development by facilitating cartilage homeostasis

Jeon, Jimin,Kang, Li&#x2010,Jung,Lee, Kwang Min,Cho, Chanmi,Song, Eun Kyung,Kim, Wook,Park, Tae Joo,Yang, Siyoung John Wiley and Sons Inc. 2018 JOURNAL OF CELLULAR AND MOLECULAR MEDICINE Vol.22 No.1

<P><B>Abstract</B></P><P>3′‐Sialyllactose has specific physiological functions in a variety of tissues; however, its effects on osteoarthritic development remain unknown. Here, we demonstrated the function of 3′‐sialyllactose on osteoarthritic cartilage destruction. <I>In vitro</I> and <I>ex vivo</I>, biochemical and histological analysis demonstrated that 3′‐sialyllactose was sufficient to restore the synthesis of Col2a1 and accumulation of sulphated proteoglycan, a critical factor for cartilage regeneration in osteoarthritic development, and blocked the expression of Mmp3, Mmp13 and Cox2 induced by IL‐1β, IL‐6, IL‐17 and TNF‐α, which mediates cartilage degradation. Further, reporter gene assays revealed that the activity of Sox9 as a transcription factor for Col2a1 expression was accelerated by 3′‐sialyllactose, whereas the direct binding of NF‐κB to the <I>Mmp3</I>,<I> Mmp13</I> and <I>Cox2</I> promoters was reduced by 3′‐sialyllactose in IL‐1β‐treated chondrocytes. Additionally, IL‐1β induction of Erk phosphorylation and IκB degradation, representing a critical signal pathway for osteoarthritic development, was totally blocked by 3′‐sialyllactose in a dose‐dependent manner. <I>In vivo</I>, 3′‐sialyllactose protected against osteoarthritic cartilage destruction in an osteoarthritis mouse model induced by destabilization of the medial meniscus, as demonstrated by histopathological analysis. Our results strongly suggest that 3′‐sialyllactose may ameliorate osteoarthritic cartilage destruction by cartilage regeneration <I>via</I> promoting Col2a1 production and may inhibit cartilage degradation and inflammation by suppressing Mmp3, Mmp13 and Cox2 expression. The effects of 3′‐sialyllactose could be attributed in part to its regulation of Sox9 or NF‐κB and inhibition of Erk phosphorylation and IκB degradation. Taken together, these effects indicate that 3′‐sialyllactose merits consideration as a natural therapeutic agent for protecting against osteoarthritis.</P>

Proprotein convertase inhibition promotes ciliated cell differentiation – a potential mechanism for the inhibition of Notch1 signalling by decanoyl‐RVKR‐chloromethylketone

Lee, Sang&#x2010,Nam,Choi, In&#x2010,Suk,Kim, Hyun Jun,Yang, Eun Jin,Min, Hyun Jin,Yoon, Joo&#x2010,Heon John Wiley and Sons Inc. 2017 JOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MED Vol.11 No.9

<P><B>Abstract</B></P><P>Chronic repetitive rounds of injury and repair in the airway lead to airway remodelling, including ciliated cell loss and mucous cell hyperplasia. Airway remodelling is mediated by many growth and differentiation factors including Notch1, which are proteolytically processed by proprotein convertases (PCs). The present study evaluated a novel approach for controlling basal cell‐type determination based on the inhibition of PCs. It was found that decanoyl‐RVKR‐chloromethylketone (CMK), a PC inhibitor, promotes ciliated cell differentiation and has no effect on the ciliary beat frequency in air–liquid interface (ALI) cultures of human nasal epithelial cells (HNECs). Comparative microarray analysis revealed that CMK considerably increases ciliogenesis‐related gene expression. Use of cell‐permeable and cell‐impermeable PC inhibitors suggests that intracellular PCs regulate basal cell‐type determination in ALI culture. Furthermore, CMK effect on ciliated cell differentiation was reversed by a Notch inhibitor <I>N</I>‐[<I>N</I>‐(3,5‐difluorophenacetyl)‐l‐alanyl]‐S‐phenylglycine <I>t</I>‐butyl ester (DAPT). CMK inhibited the processing of Notch1, a key regulator of basal cell differentiation toward secretory cell lineages in the airway epithelium, and down‐regulated the expression of Notch1 target genes together with furin, a PC. Specific lentiviral shRNA‐mediated knockdown of <I>furin</I> resulted in reduced Notch1 processing and increased numbers of ciliated cells in HNECs. Moreover, CMK inhibited Notch1 processing and promoted regeneration and ciliogenesis of the mouse nasal respiratory epithelium after ZnSO<SUB>4</SUB> injury. These observations suggest that PC inhibition promotes airway ciliated cell differentiation, possibly through suppression of furin‐mediated Notch1 processing. © 2016 The Authors Journal of Tissue Engineering and Regenerative Medicine Published by John Wiley & Sons Ltd</P>

Overexpression of <i>OsTF1L,</i> a rice HD‐Zip transcription factor, promotes lignin biosynthesis and stomatal closure that improves drought tolerance

Bang, Seung Woon,Lee, Dong&#x2010,Keun,Jung, Harin,Chung, Pil Joong,Kim, Youn Shic,Choi, Yang Do,Suh, Joo&#x2010,Won,Kim, Ju&#x2010,Kon BLACKWELL 2019 PLANT BIOTECHNOLOGY JOURNAL Vol.17 No.1

<P><B>Summary</B></P><P>Drought stress seriously impacts on plant development and productivity. Improvement of drought tolerance without yield penalty is a great challenge in crop biotechnology. Here, we report that the rice (<I>Oryza sativa</I>) homeodomain‐leucine zipper transcription factor gene, <I>OsTF1L</I> (<I>Oryza sativa transcription factor 1‐like</I>), is a key regulator of drought tolerance mechanisms. Overexpression of the <I>OsTF1L</I> in rice significantly increased drought tolerance at the vegetative stages of growth and promoted both effective photosynthesis and a reduction in the water loss rate under drought conditions. Importantly, the <I>OsTF1L</I> overexpressing plants showed a higher drought tolerance at the reproductive stage of growth with a higher grain yield than nontransgenic controls under field‐drought conditions. Genomewide analysis of <I>OsTF1L</I> overexpression plants revealed up‐regulation of drought‐inducible, stomatal movement and lignin biosynthetic genes. Overexpression of <I>OsTF1L</I> promoted accumulation of lignin in shoots, whereas the RNAi lines showed opposite patterns of lignin accumulation. <I>OsTF1L</I> is mainly expressed in outer cell layers including the epidermis, and the vasculature of the shoots, which coincides with areas of lignification. In addition, <I>OsTF1L</I> overexpression enhances stomatal closure under drought conditions resulted in drought tolerance. More importantly, OsTF1L directly bound to the promoters of lignin biosynthesis and drought‐related genes involving <I>poxN/PRX38</I>,<I> Nodulin protein</I>,<I>DHHC4</I>,<I>CASPL5B1</I> and <I>AAA‐type ATPase</I>. Collectively, our results provide a new insight into the role of <I>OsTF1L</I> in enhancing drought tolerance through lignin biosynthesis and stomatal closure in rice.</P>

KR‐31378 ameliorates atherosclerosis by blocking monocyte recruitment in hypercholestrolemic mice

Kim, Jiyun,Nam, Ki&#x2010,Hoan,Kim, Sun&#x2010,Ok,Choi, Jae&#x2010,Hoon,Kim, Hyoung&#x2010,Chin,Yang, Sung&#x2010,Don,Kang, Joo&#x2010,Hyoung,Ryu, Young&#x2010,Han,Taeg Oh, Goo,Yoo, Sung&#x2010,Eun Federation of American Society for Experimental Bi 2004 The FASEB Journal Vol.18 No.6

<P>The recruitment of monocytes into the artery wall is a crucial early step in atherogenesis. A novel compound, KR-31378, has been shown to be a neuroprotective agent for ischemia-reperfusion damage in rat brain via its potent antioxidant and antiapoptotic actions. Here, we report the effects of this compound on atherogenesis and possible mechanisms of action. In Ldlr knockout mice fed with a high-fat, high-cholesterol diet, treatment with KR-31378 significantly inhibited fatty streak formation and macrophage accumulation. To address the possibility that KR-31378 may influence the initial stages of atherogenesis, we examined its effect on the adhesion and migration of monocytes to endothelial cells stimulated with tumor necrosis factor-alpha. KR-31378 decreased the adhesion in a dose-dependent manner. The observed decreases in cell adhesion and migration correlated with KR-31378-mediated down-regulation of vascular cell adhesion molecule-1 (VCAM-1) and interleukin (IL)-8. Nuclear factor-kappaB (NF-kappaB) is known to regulate the expression of adhesive and chemotactic molecules including VCAM-1 and IL-8. Indeed, transient transfection experiments, electrophoretic mobility shift assay, and IkappaB degradation assay showed that KR-31378 decreased NF-kappaB activation. These results indicate that KR-31378 potently reduces fatty streak formation by inhibiting NF-kappaB-dependent cellular adhesion and chemotactic molecule expression, which are crucial to monocyte infiltration into the arterial wall during the early stages of atherogenesis.</P>

STAT3 is a potential modulator of HIF‐1‐mediated VEGF expression in human renal carcinoma cells

Jung, Joo Eun,Lee, Hyun&#x2010,Gyu,Cho, Ik&#x2010,Hyun,Chung, Doo Hyun,Yoon, Sun&#x2010,Hee,Yang, Young Mok,Lee, Jung Weon,Choi, Seongwon,Park, Jong&#x2010,Wan,Ye, Sang&#x2010,Kyu,Chung, Myung&#x2010 Federation of American Society for Experimental Bi 2005 The FASEB Journal Vol.19 No.10

<P>Aberrantly enhanced vascular endothelial growth factor (VEGF) gene expression is associated with increased tumor growth and metastatic spread of solid malignancies, including human renal carcinomas. Persistent activation of STAT3 is linked to tumor-associated angiogenesis, but underlying mechanisms remain unclear. Therefore, we examined whether STAT3 modulates the stability and activity of hypoxia-inducible factor-1alpha (HIF-1alpha), and in turn enhances VEGF expression. We found that STAT3 was activated in ischemic rat kidneys and hypoxic human renal carcinoma cells. We also found that hypoxia-induced activation of STAT3 transactivated the VEGF promoter and increased the expression of VEGF transcripts. Consistent with these findings, STAT3 inhibition attenuated the hypoxic induction of VEGF. Interestingly, activated STAT3 increased HIF-1alpha protein levels due to the HIF-1alpha stability by blocking HIF-1alpha degradation and accelerated its de novo synthesis. The novel interaction of STAT3 with HIF-1alpha was identified in hypoxic renal carcinoma cells. Furthermore, hypoxia recruited STAT3, HIF-1alpha, and p300 to the VEGF promoter and induced histone H3 acetylation. Therefore, these findings provide compelling evidence that a causal relationship exists between STAT3 activation and HIF-1-dependent angiogenesis and suggest that therapeutic modalities designed to disrupt STAT3 signaling hold considerable promise for the blocking tumor growth and enhancing apoptosis of cancer cells and tissues.</P>

Spatially Resolved Photodetection in Leaky Ferroelectric BiFeO₃

Lee, Won&#x2010,Mo,Sung, Ji Ho,Chu, Kanghyun,Moya, Xavier,Lee, Donghun,Kim, Cheol&#x2010,Joo,Mathur, Neil D.,Cheong, S.&#x2010,W.,Yang, C.&#x2010,H.,Jo, Moon&#x2010,Ho WILEY‐VCH Verlag 2012 Advanced Materials Vol.24 No.10

<P><B>Potential gradients due to the spontaneous polarization of BiFeO<SUB>3</SUB></B> yield asymmetric and nonlinear photocarrier dynamics. Photocurrent direction is determined by local ferroelectric domain orientation, whereas magnitude is spectrally centered around charged domain walls that are associated with oxygen vacancy migration. Photodetection can be electrically controlled by manipulating ferroelectric domain configurations.</P>

Photoconductivity of C₆₀ as an Origin of Bias‐Dependent Photocurrent in Organic Photovoltaics

Jeong, Won&#x2010,Ik,Lee, Yang Eun,Shim, Hyun&#x2010,Sub,Kim, Tae&#x2010,Min,Kim, Sei&#x2010,Yong,Kim, Jang&#x2010,Joo WILEY‐VCH Verlag 2012 Advanced functional materials Vol.22 No.14

<P><B>Abstract</B></P><P>The bulk‐ionized photoconductivity of C<SUB>60</SUB> is reported as an origin of the bias‐dependent linear change of the photocurrent in copper phthalocyanine (CuPc)/C<SUB>60</SUB> planar heterojunction solar cells, based on the observation of the variation of the bias‐dependent photocurrent on excitation wavelengths and the thickness‐dependent photocurrent of the C<SUB>60</SUB> layer. A theoretical model, which is a combination of the Braun‐Onsager model for the dissociation of excitons at the donor/acceptor interface and the Onsager model for the bulk ionization of excitons in the C<SUB>60</SUB> layer, describes the bias‐dependent photocurrent in the devices very well. The bulk‐ionized photoconductivity of C<SUB>60</SUB> must generally contribute to the photocurrent in organic photovoltaics, since fullerene and fullerene derivatives are widely used in these devices.</P>

Formation of a Continuous Solid‐Solution Particle and its Application to Rechargeable Lithium Batteries

Noh, Hyung&#x2010,Joo,Myung, Seung&#x2010,Taek,Jung, Hun&#x2010,Gi,Yashiro, Hitoshi,Amine, Khalil,Sun, Yang‐,Kook WILEY‐VCH Verlag 2013 Advanced functional materials Vol.23 No.8

<P><B>Abstract</B></P><P>High‐energy electrode materials are under worldwide development for rechargeable lithium batteries to be used in electric vehicles and other energy storage applications. High capacity and energy density are readily achievable using Ni‐rich Li[Ni<SUB>1‐<I>x</I></SUB>M<SUB><I>x</I></SUB>]O<SUB>2</SUB> (<I>x</I> = 0.1–0.2, M = Ni, Co, Mn, and Al) cathodes. Unfortunately, their structural instability is associated with severe capacity fading on cycling, which hinders practical applications. Here, a method is presented for producing a continuous compositional change between Li[Ni<SUB>0.8</SUB>Co<SUB>0.2</SUB>]O<SUB>2</SUB> (center) and Li[Ni<SUB>0.8</SUB>Co<SUB>0.01</SUB>Mn<SUB>0.19</SUB>]O<SUB>2</SUB> (surface) in a spherical particle, resulting in an average composition of Li[Ni<SUB>0.8</SUB>Co<SUB>0.06</SUB>Mn<SUB>0.14</SUB>]O<SUB>2</SUB>. The chemical composition in the particle is gradually altered by decreasing the Co concentration while adding Mn content. The Ni content remains fixed. Coin cells with the solid‐solution cathode deliver a specific capacity over 210 mAh g<SUP>−1</SUP> in the voltage range of 2.7–4.3 V vs. Li/Li<SUP>+</SUP> with capacity retention of 85% over 100 cycles at 25 and 55 °C. The main exothermic temperature upon heating appears at around 250 °C with relatively low heat generation (810 J g<SUP>−1</SUP>). The presence of the tetravalent Mn at the particle surface is mainly responsible for the high capacity upon cycling and excellent thermal properties.</P>