Mitochondrial Ca²⁺ Uptake Relieves Palmitate-Induced Cytosolic Ca²⁺ Overload in MIN6 Cells

Ly, Luong Dai,Ly, Dat Da,Nguyen, Nhung Thi,Kim, Ji-Hee,Yoo, Heesuk,Chung, Jongkyeong,Lee, Myung-Shik,Cha, Seung-Kuy,Park, Kyu-Sang Korean Society for Molecular and Cellular Biology 2020 Molecules and cells Vol.43 No.1

Saturated fatty acids contribute to β-cell dysfunction in the onset of type 2 diabetes mellitus. Cellular responses to lipotoxicity include oxidative stress, endoplasmic reticulum (ER) stress, and blockage of autophagy. Palmitate induces ER Ca²⁺ depletion followed by notable store-operated Ca²⁺ entry. Subsequent elevation of cytosolic Ca²⁺ can activate undesirable signaling pathways culminating in cell death. Mitochondrial Ca²⁺ uniporter (MCU) is the major route for Ca²⁺ uptake into the matrix and couples metabolism with insulin secretion. However, it has been unclear whether mitochondrial Ca²⁺ uptake plays a protective role or contributes to lipotoxicity. Here, we observed palmitate upregulated MCU protein expression in a mouse clonal β-cell, MIN6, under normal glucose, but not high glucose medium. Palmitate elevated baseline cytosolic Ca²⁺ concentration ([Ca²⁺]_i) and reduced depolarization-triggered Ca²⁺ influx likely due to the inactivation of voltage-gated Ca²⁺ channels (VGCCs). Targeted reduction of MCU expression using RNA interference abolished mitochondrial superoxide production but exacerbated palmitate-induced [Ca²⁺]_i overload. Consequently, MCU knockdown aggravated blockage of autophagic degradation. In contrast, co-treatment with verapamil, a VGCC inhibitor, prevented palmitate-induced basal [Ca²⁺]_i elevation and defective [Ca²⁺]_i transients. Extracellular Ca²⁺ chelation as well as VGCC inhibitors effectively rescued autophagy defects and cytotoxicity. These observations suggest enhanced mitochondrial Ca²⁺ uptake via MCU upregulation is a mechanism by which pancreatic β-cells are able to alleviate cytosolic Ca²⁺ overload and its detrimental consequences.

Geological and mineralization characteristics of the Kestanelik epithermal Au-Ag deposit in the Tethyan Metallogenic Belt, NW Turkey

Nilay Gülyüz,Erhan Gülyüz,Zoe K. Shipton,İlkay Kuşcu,Richard A. Lord 한국지질과학협의회 2020 Geosciences Journal Vol.24 No.4

Kestanelik epithermal gold deposit is situated in the Biga Peninsula, which hosts numerous metallic deposits belonging to the Tethyan Metallogenic Belt. In the Biga peninsula the Tethyan Metallogenic Belt is represented by a Neo-Tethyan suture zone. Discovered deposits along the belt are commonly associated with Cenozoic magmatism ranging between 52 and 18 Ma in age, formed due syn- to post-collisional tectonics. In this study, we focus on the deposit-scale geological and mineralization characteristics of Kestanelik in order to determine the formation and evolution of the deposit within the tectono-magmatic history of the Biga Peninsula. We (1) mapped the geology of the deposit area (2) conducted paleostress analyses, (3) observed and examined the macroscopic and petrographical textural, mineralogical and alteration characteristics of the mineralization and (4) interpreted geophysical resistivity survey and geochemical assay data. The stratigraphic age of the Kestanelik deposit, bracketed by cross cutting relations and supported by the geophysical data, is middle Lutetian–early Priabonian which also implies that the deposit has a genetic link with the Cenozoic post-collisional calc-alkaline magmatism. A NE-SW oriented compressional regime determined from the paleostress analyses is consistent with the kinematics of the vein system and is attributed to the collision and further convergence after the closure of the northern branch of the Neo-Tethys Ocean. The fracture system provided structural pathways for the transport of the hydrothermal fluids. The common presence of pseudo-bladed quartz and hydrothermal breccias, and the low total sulphide and base metal contents in the mineralized veins indicate that the Kestanelik is a low sulphidation epithermal-type gold deposit. Boiling, mixing (hypogene oxidation) and supergene enrichment are the likely gold deposition and enrichment processes respectively.

Raman spectroscopy of pH-induced release of zidovudine from lactobionic acid-conjugated PEGylated gold colloids

Ly, Nguyễ,n Hoà,ng,Nguyen, Thanh Danh,Joo, Sang-Woo Elsevier 2018 Colloids and Surfaces B Vol.171 No.-

<P><B>Abstract</B></P> <P>Zidovudine (AZT) adsorbed on colloidal gold nanoparticles (AuNPs) undergoes pH-induced conformational changes according to spectral changes in surface-enhanced Raman scattering (SERS). In acidic pH values conditions, AZT assumes the C<SUB>(2ʹ)</SUB>-endo conformer, which binds more weakly to AuNPs than under neutral and alkaline conditions. In this study, density functional theory (DFT) calculations were performed; these calculations also supported the conformation-dependent binding energies. A lactobionic acid-conjugated PEGylated (LA-PEG-SH; molecular weight: 3400) unit was attached to AuNPs to target the asialoglycoprotein receptors overexpressed in hepatocarcinoma cells of Huh7 and SNU-354. The loading efficiency values were measured to be ∼44–49% and ∼66–68% at pH values of 7 and 10, respectively. At an acidic pH of 4.5, they were estimated to be only ∼35–38%. pH-dependent spectral changes were observed for the asymmetric stretching modes of the azide (NNN) bands at 2183 cm<SUP>−1</SUP> (in acidic pH) and at 2129 cm<SUP>−1</SUP> (in basic pH). Cell viability analysis indicated that the LA-PEG-capped, AZT-coated AuNPs specifically inhibited the growth of the targeted hepatocarcinoma cells with better cancer cell killing efficiency than was observed with the LA-PEG-capped AuNPs without AZT.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Zidovudine bound to colloidal gold nanoparticles undergoes pH-induced conformational changes. </LI> <LI> At acidic pH values, zidovudine assumes the C<SUB>(2ʹ)</SUB>-endo conformer, which binds weakly to gold. </LI> <LI> Cytotoxicity analysis indicated that the complex could inhibit the growth of the targeted hepatocarcinoma cells. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Conformational change-induced drug release of zidovudine from gold nanoparticles in acidic pH conditions was studied by Raman spectroscopy and density functional theory.</P> <P>[DISPLAY OMISSION]</P>

Human-Urine Diabetes Assay and In Vivo Rat Bladder Assay Using a Fluorine-Doped Carbon Nanotube Catheter Sensor

Ly, Suw Young,Lee, Jin Hui Springer-Verlag 2009 Annals of biomedical engineering Vol.37 No.10

IDENTIFYING CURRENT ISSUES OF BIM-BASED COLLABORATION BETWEEN DESIGNERS AND CONTRACTORS UNDER A DBB CONTRACT

Ly, Dang-Huy(이당휘),Hwang, Sang-Jun(황상준),Cho, Jae-Youn(조재윤),Ahn, Yong-han(안용한) 대한건축학회 2021 대한건축학회 학술발표대회 논문집 Vol.41 No.1

Radioactive uranium measurement in vivo using a handheld interfaced analyzer.

Ly, Suw Young,Lee, Jin-Hui,Jung, Dong Ho Pergamon 2010 Environmental toxicology and chemistry Vol.29 No.5

<P>A trace uranium (U) detection method was developed with a handheld voltammetric analyzer that was the size of a mobile phone, with working sensors made of simple graphite pencil electrode (PE). The optimum stripping voltammetric conditions were sought, and the following results were obtained: 0.0 to 0.08 ng/L working ranges and a statistically relative standard deviation of 1.78% (RSD; n=15) at a 10.0 microg/L U spike. The experiment accumulation time used was only 150 s. Under this condition, the diagnostic detection limit approached 0.007 ng/L. The method was applied to soil of a natural rock in a radioactive mineralogy site. Earthworms that resided at this site were assayed. The method was found to be applicable in biological diagnosis or in real-time in vivo survey.</P>

Trace Uranium Assay Using Infrared Photo Diode Electrodes

Ly, S. Y.,Choa, S. H.,Shin, M. H.,Kim, S. R.,Yoo, H. S.,Shin, H. J.,Jung, Y. S.,Choi, J. B. Taylor Francis 2010 Analytical letters Vol.43 No.9

Analysis of Lead Ions in a Waste Solution Using Infrared Photo-Diode Electrode

Ly, Suw-Young,Lee, Hyun-Kuy,Kwak, Kyu-Ju,Ko, Jun-Seok,Lee, Jeong-Jae,Cho, Jin-Hee,Kim, Ki-Hong,Kim, Min-Seok,Lee, So-Jung Korean Society of ToxicologyKorea Environmental Mu 2008 Toxicological Research Vol.25 No.4

To detect lead ions using electrochemical voltammetric analysis, Infrared Photo-Diode Electrode(IPDE) was applied via cyclic and square wave stripping voltammetry. Lead ions were deposited at 0.5 V(versus Ag/AgCl) accumulation potential. Instrumental measurements systems were made based on a simple and compact detection system. The stripping voltammetric and cyclic voltammetric optimal parameters were searched. The results yielded a cyclic range of $40{\sim}240mgl^{-1}$ Pb(II) and a square wave stripping working range of $0.5{\sim}5.00mgl^{-1}$ Pb(II). The relative standard deviation at 2 and 4 $mgl^{-1}$ Pb(II) was 0.04% and 0.02%(n=15), respectively, using the stripping voltammetric conditions. The detection limit was found to be 0.05 $mgl^{-1}$ with a 40 sec preconcentration time. Analytical interference ions were also evaluated. The proposed method was applied to determine lead ions in various samples.

Fast pyrolysis of Saccharina japonica alga in a fixed-bed reactor for bio-oil production

Ly, H.V.,Kim, S.S.,Choi, J.H.,Woo, H.C.,Kim, J. Pergamon ; Elsevier Science Ltd 2016 Energy conversion and management Vol.122 No.-

Macro-algae are recognized as a potential feedstock for renewable energy and fuel production. Saccharina japonica is a kind of macro-algae that has been extensively cultivated in Korea. Through pyrolysis, S. japonica can be converted into bio-oil, gas, and char. In this study, we investigated the fast pyrolysis of S. japonica in a fixed-bed reactor at different temperatures from 350 to 550<SUP>o</SUP>C with sweeping-gas flow rates of 100, 300, and 500ml/min. As the pyrolysis temperature was increased from 350<SUP>o</SUP>C to 500<SUP>o</SUP>C, the bio-oil yields decreased while the gas yields increased. The highest liquid yield (40.91wt%) was obtained at a pyrolysis temperature of 350<SUP>o</SUP>C with a sweeping-gas velocity of 300ml/min. The major compositions in the bio-oil were di-anhydromannitol (34.45%), iso-sorbide (19.84%), and 2-methyl furyl ketone (8.43%). The gas products (including CO, CO<SUB>2</SUB>, H<SUB>2</SUB>, and hydrocarbon gases from C<SUB>1</SUB> to C<SUB>4</SUB>), were analyzed by gas chromatography with an FID and a TCD. The bio-chars contained a high carbonaceous content can be used as a pollution-free solid fuel or for the production of activated carbon and other chemicals.

Spectroscopic measurements of interactions between hydrophobic 1-pyrenebutyric acid and silver colloidal nanoparticles

Ly, Nguyen Hoang,Nguyen, Thanh Danh,Bui, Thanh Lam,Lee, Sangyeop,Choo, Jaebum,Joo, Sang-Woo Elsevier 2017 Colloids and surfaces. A, Physicochemical and engi Vol.518 No.-

<P><B>Abstract</B></P> <P>We compared the adsorption and desorption of 1-pyrenecarboxylic acid (PyC), 1-pyreneacetic acid (PyA), and 1-pyrenebutyric acid (PyB) on silver nanoparticles (AgNPs) via interfacial spectroscopic tools to study the role of the aliphatic units between pyrene and carboxylic group. The negative surface charges of AgNPs at ca. −51mV shifted up to −11mV, after adsorbing hydrophobic pyrene compounds. The three pyrene acid compounds appeared to adsorb onto AgNPs via their carboxylate units by referring to the observation of the broad <I>ν</I>(COO<SUP>−</SUP>) bands at 1380–1410cm<SUP>−1</SUP> in the Raman spectra. X-ray photoelectron spectroscopy (XPS) also supported the CO species in the C<SUB>1s</SUB> region. AgNPs were found to efficiently quench the fluorescence of the three pyrene acid adsorbates. The highest Stern–Volmer constant of PyA may be due to the largest overlap integral with the surface Plasmon absorption band of AgNPs. The butyric unit was expected to lead a stronger binding on Ag, as suggested by density functional theory (DFT) calculations. The adsorbed pyrene acid compounds appeared to be released from AgNPs by thiol-containing glutathione (GSH). PyB with the butyric group exhibited larger quenched fluorescence intensities and smaller released amounts than PyC and PyA in aqueous solutions and A549 cancer cells. Our study will be helpful in designing pyrene-based fluorescence sensors in cellular imaging.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Hydrophobic pyrene acids were chemically interacted with Ag nanoparticles. </LI> <LI> 1-Pyrene acids were found to adsorb on silver via the COO<SUP>−</SUP> bonds. </LI> <LI> Fluorescence quenching behaviors of pyrene acids were compared on Ag. </LI> <LI> Glutathione-triggered desorption of pyrene acids were observed in cancer cells. </LI> <LI> 1-Pyrenebutyrate showed stronger binding than 1-pyrenecarboxlyate on Ag. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>