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.

Atomistic study of the alloying behavior of crystalline SnSe1-xSx

Ly, T.,Duvjir, G.,Min, T.,Byun, J.,Kim, T.,Saad, M.,Hai, N.,Cho, S.,Lee, J.,Kim, J. Royal Society of Chemistry 2017 Physical chemistry chemical physics Vol.19 No.32

Influencing Factors of Purchase Intention on Social Commerce in Cambodia : The Moderating Roles of Experience

Ly, Pichponreay,Cho, Wan-Sup,Kwon, Sun-Dong Korea Data Strategy Society 2017 Journal of information technology applications & m Vol.24 No.1

Cambodia retail industry starts to entry SNS market. The online market of Cambodia is very unique. Facebook users of Cambodia are purchasing products, without electronic payment and delivery system. Therefore, this study focused on the immature online environment, proved the influencing factors of purchase intention on SNS. And also this study proved that the influencing factors on purchase intention are different, depending on whether or not a purchase experience exists. As results of analyzing with full data, price reduction, convenience, and customer service had significant impacts on purchase intention. The experienced group has significant effects of price reduction and customer service on purchase intention, while the inexperienced group has significant effects of convenience and customer service on purchase intention. This study provides marketing and strategic implications for companies seeking to enter the online market of Cambodia.

Superior Dielectric Screening in Two-Dimensional MoS₂ Spirals

Ly, Thuc Hue,Kim, Hyun,Thi, Quoc Huy,Lau, Shu Ping,Zhao, Jiong American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.43

<P>Metals have the best dielectric screening capability among all materials; however, it is usually difficult to fabricate continuous and uniform ultrathin (few-atomic-layer thickness) metal films. Conversely, high-quality atomic-thick semiconductor or semimetal materials (so called two-dimensional materials) such as graphene or MoS2 can be readily obtained and robust in ambient conditions; however, their dielectric screening capabilities are greatly reduced by their reduced dimensionality. Particularly, in the vertical direction, the dielectric screening of two-dimensional materials is insufficient; thus, the performances of devices by two-dimensional materials were easily affected by the coulomb-scattering or other kind of sources. Herein, we propose that with a screw dislocation connecting the van der Waals layers in two-dimensional MoS2 spiral structures, excellent dielectric screening in the vertical direction can be achieved. Our Kelvin force microscopy directly demonstrates that the external impurity charges can be perfectly screened by a theoretically minimum number of layers (two layers) in the MoS2 spirals. This spiral structure-assisted screening approach paves new way to the design of high-performance ultrathin electrical and optical devices.</P>

Diagnostic ex vivo assay of glucose in live cell using voltammetry

Ly, Suw Young,Leea, Chang Hyun The Korean Society of Applied Science and Technolo 2018 한국응용과학기술학회지 Vol.35 No.4

The hand held voltammetry systems searched diabetic assay using glucose sensor of fluorine nafion doped carbon nanotube electrode (FCNE). An inexpensive graphite carbon pencil was used as an Ag/AgCl reference and Pt counter electrode. Upon combining and using three electrode systems, optimum square wave (SW) stripping results were attained to 1.0-9.0 ug/L with 8 points. Statistic RSD precision was of 6.02 % with n=15 in 0.1 mg/L glucose. After a total of 200 second accumulation times, analytical detection limit of 0.8 ug/L was obtained. This developed technique was applied to urine samples from diabetic patients urine for fluid analysis, it was determined that the sensor can be used with a diagnostics in the ex vivo of live cells and non treated biological fluid.

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.

Catalytic pyrolysis of tulip tree (<i>Liriodendron</i>) in bubbling fluidized-bed reactor for upgrading bio-oil using dolomite catalyst

Ly, Hoang Vu,Lim, Dong-Hyeon,Sim, Jae Wook,Kim, Seung-Soo,Kim, Jinsoo Elsevier 2018 ENERGY Vol.162 No.-

<P><B>Abstract</B></P> <P>Fractional catalytic pyrolysis is an updated pyrolysis method, in which the biomass can be converted into higher quality bio-oil by upgrading the pyrolysis vapor in fluidized bed. In this study, the fast pyrolysis of tulip tree (<I>Liriodendron</I>) was performed in a bubbling fluidized-bed reactor under various reaction conditions (pyrolysis temperature, flow rate of fluidizing medium, and biomass particle size) to investigate the effects of these parameters on product yield and bio-oil quality. The system used silica sand and dolomite as the fluidizing bed material, and nitrogen as the fluidizing medium. When the pyrolysis temperature increased from 400 °C to 550 °C, the bio-oil yield was between 40.07 wt% and 49.03 wt% compared to those of 28.38 and 44.83 wt% using dolomite catalyst. Deoxygenation of bio-oil mostly produced water, and produced lower amounts of CO and CO<SUB>2</SUB>, but higher amounts of H<SUB>2</SUB> and hydrocarbons gas. The catalytic process obtaineda high ratio of H<SUB>2</SUB>/CO in the gas product.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Pyrolysis of tulip tree in fluidized bed reactor under different conditions. </LI> <LI> Catalytic pyrolysis using dolomite catalyst for upgrading bio-oil's quality. </LI> <LI> Dolomite rejected oxygen from pyrolysis vapor, mostly through dehydration. </LI> <LI> The catalytic process produced high H<SUB>2</SUB>/CO ratio in the gas product. </LI> </UL> </P>

Real-time Voltammetric Assay of Cadmium Ions in Plant Tissue and Fish Brain Core

Ly, Suw-Young Korean Chemical Society 2006 Bulletin of the Korean Chemical Society Vol.27 No.10

Optimum analytical conditions for cyclic voltammetry (CV) and square wave (SW) stripping voltammetry were determined using mercury-mixed carbon nanotube paste electrode (PE). The results approached the microgram working ranges of SW: 10.0-80.0 $ugL^{-1}$ and CV: 100-700 $ugL^{-1}$ Cd (II); working conditions of 300-Hz frequency, 100 mV amplitude, 1.6 V accumulation potential, 400 sec accumulation time, and 40 mV increment potential. First, analysis was performed through direct assay of cadmium ions deep into the fishs brain core and plant tissue in real time with a preconcentration time of 400 sec. The relative standard deviation of 10.0 $mgL^{-1}$ Cd (II) observed was 0.064 (n = 12) at optimum conditions. The low detection limit (S/N) was set at 0.6 $ugL^{-1}$ ($5.33{\times}10^{-9}$ M). The methods can be used in direct analysis in vivo or in real-time monitoring of plant tissue.

Direct Assay of Riboflavin in Cow's Milk Using Graphite Pencil Electrode

Ly, Suw Young 서울産業大學校 2005 논문집 Vol.54 No.4

Direct detecting method of riboflavin (vitamin B2.VB2) in cow's milk was developed using stripping voltammetry analysis with graphite pencil electrode (GPE). The results show a sensitive oxidation peak current of VB₂ on the GPE. Commonly used working electrodes were compared and better results were obtained with GPE than with the common electrodes. Analytical working concentration ranged within 10-100.0 and 50.0-350 mgL^(-1)VB₂, with pre-concentration time of 160 sec. The relative standard deviation of 50, 150, and 200 mgL^(-1) observed were 0.069, 0.084, and 0.081% (n = 15), respectively, using optimum conditions. The detection limit (S/N) was pegged at 0.20 ugL^(-1). Results show that the method developed can be used to assay untreated natural milk solution, as well as other materials requiring Vitamin B₂ analysis.