Identification and quantification of seven volatile n-nitrosamines in cosmetics using gas chromatography/chemical ionization-mass spectrometry coupled with head space-solid phase microextraction

Choi, N.R.,Kim, Y.P.,Ji, W.H.,Hwang, G.S.,Ahn, Y.G. Pergamon Press ; Elsevier Science Ltd 2016 Talanta Vol.148 No.-

<P>An analytical method was developed for the identification and quantification of seven volatile n-nitrosamines (n-nitrosodimethylamine [NDMA], n-nitrosoethylmethylamine [NMEA], n-nitrosodiethylamine [NDEA], n-nitrosodipropylamine [NDPA], n-nitrosodibutylamine [NDBA], n-nitrosopiperidine [NPIP], and n-nitrosopyrrolidine [NPYRD]) in water insoluble cream type cosmetics. It was found that the head space-solid phase microextraction (HS-SPME) was suitable for extraction, clean up, and pre-concentration of n-nitrosamines in the cream type samples so its optimal conditions were investigated. Identification and quantification of n-nitrosamines using single quadrupole gas chromatography/mass spectrometry (GC/MS) in chemical ionization (CI) mode were carried out with accurate mass measurements. Their accurate masses of protonated molecular ions were obtained within 10 mDa of the theoretical masses when sufficiently high signal was acquired from the unique calibration method using mass and isotope accuracy. For the method validation of quantification, spiking experiments were carried out to determine the linearity, recovery, and method detection limit (MDL) using three deuterated internal standards. The average recovery was 79% within 20% relative standard deviation (RSD) at the concentration of 50 ng/g. MDLs ranged from 0.46 ng/g to 36.54 ng/g, which was satisfactory for the directive limit of 50 ng/g proposed by the European Commission (EC). As a result, it was concluded that the method could be provided for the accurate mass screening, confirmation, and quantification of n-nitrosamines when applied to cosmetic inspection. (C) 2015 Elsevier B.V. All rights reserved.</P>

N₂/ CH₄가스비에 따른 Hydrogenated Amorphous Carbon Nitride 박막의 특성

장홍규(H. K. Jang),김근식(G. S. Kim),황보상우(S. W. Whangbo),이연승(Y. S. Lee),황정남(C. N. Whang),유영조(Y. Z. Yoo),김효근(H. G. Kim) 한국진공학회(ASCT) 1998 Applied Science and Convergence Technology Vol.7 No.3

DC saddle-field-plasma-enhanced chemical-vapor deposition(PECVD) 장치를 이용하여 상온에서 p-type Si (100) 기판위에 hydrogenated amorphous carbon nitride [a-C:H(N)]박막을 증착하였다. 원료가스인 CH₄과 N₂의 전체압력은 90 mTorr로 고정하고 N₂/CH₄비를 0에서 4까지 변화하면서 제작한 a-C:H(N) 박막의 미세 구조의 변화를 연구하였다. 진공조의 도달 진공도는 1×10^(-6) Torr이고, 본 실험시 CH₄+N₂가스의 유량은 5 sc㎝으로 고정하고 배기량을 조절하여 진공조의 가스 압력을 90 mTorr로 고정하였으며 기판에 200 V의 직류 bias 전압을 인가하였다. α-step과 X-ray photoelectron spectroscopy(XPS)를 이용한 분석결과 N₂/CH₄비가 0에서 0.5로 증가함에 따라 박막 두께는 4840 Å에서 2600 Å으로 급격히 감소하였으며, 박막내의 탄소에 대한 질소함유량(N/C비)는 N₂/CH₄비가 4일때 최대 0.25로 증가하는 것을 확인하였다. 또한 XPS 스펙트럼의 fitting 결과 N₂/CH₄비가 증가할수록 CN결합이 증가하였다. Fourier Transformation Infrared (FT-IR) 분석결과 N₂/CH₄비가 증가함에 따라 박막내의 C-H 결합은 감소하고, N-H, C≡N 결합은 증가하였다. Optical bandgap 측정 결 과 N₂/CH₄비가 0에서 4로 증가함에 따라 a-C:H(N)박막의 bandgap 에너지는 2.53 eV에서 2.3 eV로 감소하는 것을 확인하였다. Hydrogenated amorphous carbon nitride[a-C:H(N)] films were deposited on p-type Si(100) at room temperature with substrate bias voltage of 200 V by DC saddle-field plasma-enhanced chemical vapor deposition. Effects of the ratio of N₂to CH₄(N₂/CH₄), in the range of 0 and 4 on such properties as optical properties, microstucture, relative fraction of nitrogen and carbon, etc. of the films have been investigated. The thickness of the a-C:H(N) film was abruptly decreased with the addition of nitrogen, but at N₂/CH₄> 0.5, the thickness of the film gradually decreased with the increase of the N₂/CH₄. The ratio of N to C(N/C) of the films was saturated at 0.25 with the increase of N₂/CH₄. N-H, C≡N bonds of the films increased but C-H bond decreased with the increase of N₂/CH₄. Optical band gap energy of the film decreased from 2.53 eV deposited with pure methane to 2.3 eV at the ratio of N₂/CH₄=4.

Gα₁₂ gep oncogene deregulation of p53-responsive microRNAs promotes epithelial–mesenchymal transition of hepatocellular carcinoma

Yang, Y M,Lee, W H,Lee, C G,An, J,Kim, E-S,Kim, S H,Lee, S-K,Lee, C H,Dhanasekaran, D N,Moon, A,Hwang, S,Lee, S J,Park, J-W,Kim, K M,Kim, S G Macmillan Publishers Limited 2015 Oncogene Vol.34 No.22

Hepatocellular carcinoma (HCC) has a poor prognosis owing to aggressive phenotype. Gα<SUB>12</SUB> gep oncogene product couples to G-protein-coupled receptors, whose ligand levels are frequently increased in tumor microenvironments. Here, we report Gα<SUB>12</SUB> overexpression in human HCC and the resultant induction of zinc-finger E-box-binding homeobox 1 (ZEB1) as mediated by microRNA deregulation. Gα<SUB>12</SUB> expression was higher in HCC than surrounding non-tumorous tissue. Transfection of Huh7 cell with an activated mutant of Gα<SUB>12</SUB> (Gα<SUB>12</SUB>QL) deregulated microRNA (miRNA or miR)-200b/a/429, -194-2/192 and -194-1/215 clusters in the miRNome. cDNA microarray analyses disclosed the targets affected by Gα<SUB>12</SUB> gene knockout. An integrative network of miRNAs and mRNA changes enabled us to predict ZEB1 as a key molecule governed by Gα<SUB>12</SUB>. Decreases of miR-200a/b, -192 and -215 by Gα<SUB>12</SUB> caused ZEB1 induction. The ability of Gα<SUB>12</SUB> to decrease p53 levels, as a result of activating protein-1 (AP-1)/c-Jun-mediated mouse double minute 2 homolog induction, contributed to transcriptional deregulation of the miRNAs. Gα<SUB>12</SUB>QL induced ZEB1 and other epithelial–mesenchymal transition markers with fibroblastoid phenotype change. Consistently, transfection with miR-200b, -192 or -215 mimic prevented the ability of Gα<SUB>12</SUB>QL to increase tumor cell migration/invasion. In xenograft studies, sustained knockdown of Gα<SUB>12</SUB> decreased the overall growth rate and average volume of tumors derived from SK-Hep1 cell (mesenchymal-typed). In HCC patients, miR-192, -215 and/or -200a were deregulated with microvascular invasion or growth advantage. In the HCC samples with higher Gα<SUB>12</SUB> level, a correlation existed in the comparison of relative changes of Gα<SUB>12</SUB> and ZEB1. In conclusion, Gα<SUB>12</SUB> overexpressed in HCC causes ZEB1 induction by deregulating p53-responsive miRNAs, which may facilitate epithelial–mesenchymal transition and growth of liver tumor. These findings highlight the significance of Gα<SUB>12</SUB> upregulation in liver tumor progression, implicating Gα<SUB>12</SUB> as an attractive therapeutic target.

Effect of annealing of graphene layer on electrical transport and degradation of Au/graphene/n-type silicon Schottky diodes

Kim, D.J.,Kim, G.S.,Park, N.W.,Lee, W.Y.,Sim, Y.,Kim, K.S.,Seong, M.J.,Koh, J.H.,Hong, C.H.,Lee, S.K. Elsevier Sequoia 2014 JOURNAL OF ALLOYS AND COMPOUNDS Vol.612 No.-

We have investigated the effect of annealing of graphene sheets on the electrical properties of Au/graphene/n-type silicon Schottky diode. Large scale graphene sheets were grown by chemical vapor deposition and then annealed at 300, 400, and 500<SUP>o</SUP>C; one sheet was left un-annealed as the control. The diodes were fabricated by transferring the graphene sheets directly onto n-type Si substrates and the current-voltage (I-V) and capacitance-voltage (C-V) characteristics were evaluated. The average values of the Schottky barrier height (SBH) and ideality factor (η) for the as-fabricated Au/graphene/n-type silicon Schottky diode from I-V measurements were determined to be ~0.8+/-0.01eV and ~1.79+/-0.05, respectively, whereas the SBH from C-V measurements was ~0.89+/-0.01eV. The electrical transport characteristics measured at room temperature indicated that annealing of graphene sheet prior to the transfer of the graphene onto the n-Si substrates significantly reduces the electric degradation of the Schottky diodes, even though no distinct differences in other electric properties, including ideality factors and SBHs, before or after annealing of the graphene sheets were observed. Thus, by simply annealing the graphene sheets at 500<SUP>o</SUP>C, we found that the Au/graphene/n-type silicon Schottky diode showed an approximately 3.3-fold lower series resistance as compared with the un-annealed Schottky diode under air exposure of up to 7days. These annealed diodes showed significantly reduced electrical degradation by removing the potentially trapped H<SUB>2</SUB>O and/or O<SUB>2</SUB> at the interface between the graphene layer and the n-Si substrate.

Adsorption of sodium dodecyl sulfate on cleaning of an N-polar GaN surface in an alkaline solution

Kim, M.S.,Paluvai, N.R.,Kim, H.T.,Park, J.G. Elsevier 2017 Materials science & engineering. B, Advanced funct Vol.222 No.-

<P>The present study investigated the removal of contaminated particles from a polished N-polar GaN surface using an alkaline cleaning solution along with sodium dodecyl sulfate (SDS) surfactant. The zeta potential, etch rate, and particle removal efficiency (PRE) of N-polar GaN surfaces were reported. A lower etch rate and smoother N-polar GaN surface were obtained when the surface is treated with a diluted NH4OH solution. However, the etch rate and PRE of the N-polar GaN surface increased as a function of the pH of the NH4OH solution. The PRE of the N-polar GaN surface reached to 96% at pH 10 with a high surface roughness of 0.5 nm. SDS was added to the ammonia solutions to control the surface roughness. The N-polar GaN surface reached 100% PRE and surface roughness shown less than 0.4 nm when cleaned in a diluted NH4OH solution with 5 mM SDS surfactant in a megasonic bath. (C) 2017 Elsevier B.V. All rights reserved.</P>

Cytogenetic heterogeneity and their serial dynamic changes during acquisition of cytogenetic aberrations in cultured mesenchymal stem cells

Kim, J.A.,Im, K.O.,Park, S.N.,Kwon, J.S.,Kim, S.Y.,Oh, K.,Lee, D.S.,Kim, M.K.,Kim, S.W.,Jang, M.,Lee, G.,Oh, Y.M.,Lee, S.D.,Lee, D.S. Elsevier Science Publishers 2015 Mutation research Vol.777 No.-

To minimize the risk of tumorigenesis in mesenchymal stem cells (MSCs), G-banding analysis is widely used to detect chromosomal aberrations in MSCs. However, a critical limitation of G-banding is that it only reflects the status of metaphase cells, which can represent as few as 0.01% of tested cells. During routine cytogenetic testing in MSCs, we often detect chromosomal aberrations in minor cell populations. Therefore, we aimed to investigate whether such a minority of cells can expand over time or if they ultimately disappear during MSC passaging. We passaged MSCs serially while monitoring quantitative changes for each aberrant clone among heterogeneous MSCs. To investigate the cytogenetic status of interphase cells, which represent the main population, we also performed interphase FISH analysis, in combination with G-banding and telomere length determination. In human adipose tissue-derived MSCs, 4 types of chromosomal aberrations were found during culturing, and in umbilical cord MSCs, 2 types of chromosomal aberrations were observed. Sequential dynamic changes among heterogeneous aberrant clones during passaging were similar to the dynamic changes observed in cancer stem cells during disease progression. Throughout all passages, the quantitative G-banding results were inconsistent with those of the interphase FISH analysis. Interphase FISH revealed hidden aberrations in stem cell populations with normal karyotypes by G-banding analysis. We found that telomere length gradually decreased during passaging until the point at which cytogenetic aberrations appeared. The present study demonstrates that rare aberrant clones at earlier passages can become predominant clones during later passages. Considering the risk of tumorigenesis due to aberrant MSCs, we believe that our results will help to establish proper safety guidelines for MSC use. In particular, we believe it is critical to test for chromosomal aberrations using both G-banding and FISH to ensure the safety of human stem cells that are manufactured in vitro for clinical applications.

Pulse Shape Discrimination of Nuclear Recoil and Electron Recoil Events With a NaI(Tl) Crystal for Dark Matter Search

Kim, K. W.,Adhikari, G.,Adhikari, P.,Choi, S.,Ha, C.,Hahn, I. S.,Jeon, E. J.,Joo, H. W.,Kang, W. G.,Kim, H. J.,Kim, N. Y.,Kim, S. K.,Kim, Y. D.,Kim, Y. H.,Lee, H. S.,Lee, M. H.,Leonard, D. S.,Oh, S. Y IEEE 2016 IEEE transactions on nuclear science Vol.63 No.2

<P>In order to investigate discrimination between nuclear recoil and electron recoil events for the KIMS-NaI dark matter search experiment, we measured the pulse shapes produced by neutrons and gamma rays in a NaI(Tl) crystal. Relatively good pulse shape discrimination (PSD) power due to high light output of recently developed crystals makes it possible to test whether the annual modulation signal observed by the DAMA/LIBRA experiment is caused by nuclear recoil events. We applied the PSD to underground data taken with a 9.15 kg low-background and high-light-output NaI(Tl) crystal for 134 days. Good agreement between underground data and electron recoil events was observed.</P>

Direct analysis of site-specific N-glycopeptides of serological proteins in dried blood spot samples

Choi, N. Y.,Hwang, H.,Ji, E. S.,Park, G. W.,Lee, J. Y.,Lee, H. K.,Kim, J. Y.,Yoo, J. S. Springer Science + Business Media 2017 Analytical and Bioanalytical Chemistry Vol.409 No.21

<P>Dried blood spot (DBS) samples have a number of advantages, especially with respect to ease of collection, transportation, and storage and to reduce biohazard risk. N-glycosylation is a major post-translational modification of proteins in human blood that is related to a variety of biological functions, including metastasis, cell-cell interactions, inflammation, and immunization. Here, we directly analyzed tryptic N-glycopeptides from glycoproteins in DBS samples using liquid chromatography-tandem mass spectrometry (LC-MS/MS) without centrifugation of blood samples, depletion of major proteins, desalting of tryptic peptides, and enrichment of N-glycopeptides. Using this simple method, we identified a total of 41 site-specific N-glycopeptides from 16 glycoproteins in the DBS samples, from immunoglobulin gamma 1 (IgG-1, 10 mg/mL) down to complement component C7 (50 mu g/mL). Of these, 32 N-glycopeptides from 14 glycoproteins were consistently quantified over 180 days stored at room temperature. The major abundant glycoproteins in the DBS samples were IgG-1 and IgG-2, which contain nine asialo-fucosylated complex types of 16 different N-glycopeptide isoforms. Sialo-non-fucosylated complex types were primarily detected in the other glycoproteins such as alpha-1-acid glycoprotein 1, 2, alpha-1-antitypsin, alpha-2-macroglobulin, haptoglobin, hemopexin, Ig alpha 1, 2 chain C region, kininogen-1, prothrombin, and serotransferrin. We first report the characterization of site-specific N-glycoproteins in DBS samples by LC-MS/MS with minimal sample preparation.</P>

Identification and characterization of a carboxypeptidase N1 from red lip mullet (<i>Liza haematocheila</i>); revealing its immune relevance

Perera, N.C.N.,Godahewa, G.I.,Jung, Sumi,Kim, Myoung-Jin,Nam, Bo-Hye,Lee, Jehee ACADEMIC PRESS LTD 2019 FISH AND SHELLFISH IMMUNOLOGY Vol.84 No.-

<P><B>Abstract</B></P> <P>Complement system orchestrates the innate and adaptive immunity <I>via</I> the activation, recruitment, and regulation of immune molecules to destroy pathogens. However, regulation of the complement is essential to avoid injuries to the autologous tissues. The present study unveils the characteristic features of an important complement component, anaphylatoxin inactivator from red lip mullet at its molecular and functional level. Mullet carboxypeptidase N1 (MuCPN1) cDNA sequence possessed an open reading frame of 1347 bp, which encoded a protein of 449 amino acids with a predicted molecular weight of 51 kDa. <I>In silico</I> analysis discovered two domains of PM14-Zn carboxypeptidase and a C-terminal domain of M14 N/E carboxypeptidase, two zinc-binding signature motifs, and an N-glycosylation site in the MuCPN1 sequence. Homology analysis revealed that most of the residues in the sequence are conserved among the other selected homologs. Phylogeny analysis showed that MuCPN1 closely cladded with the <I>Maylandia zebra</I> CPN1 and clustered together with the teleostean counterparts. A challenge experiment showed modulated expression of MuCPN1 upon polyinosinic:polycytidylic acid and <I>Lactococcus garviae</I> in head kidney, spleen, gill, and liver tissues. The highest upregulation of MuCPN1 was observed 24 h post infection against poly I:C in each tissue. Moreover, the highest relative expressions upon <I>L. garviae</I> challenge were observed at 24 h post infection in head kidney tissue and 48 h post infection in spleen, gill, and liver tissues. MuCPN1 transfected cells triggered a 2.2-fold increase of nitric oxide (NO) production upon LPS stimulation compared to the un-transfected controls suggesting that MuCPN1 is an active protease which releases arginine from complement C3a, C4a, and C5a. These results have driven certain way towards enhancing the understanding of immune role of MuCPN1 in the complement defense mechanism of red lip mullet.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Carboxypeptidase N1 complement component was identified from the red lip mullet. </LI> <LI> Ubiquitous expression of MuCPN1 was observed in healthy mullet tissues. </LI> <LI> Modulated transcriptions of MuCPN1 revealed the importance in the immune responses. </LI> <LI> MuCPN1 was enhanced the nitric oxide production at an inflammatory condition. </LI> </UL> </P>

Stepwise selective reaction of two N-cyanoethyl groups attached to C-racemic tetraaza macrocyclic nickel(II) and copper(II) complexes in aqueous solutions

Kang, S.G.,Kim, N.,Jeong, J.H. Elsevier Sequoia [etc.] 2011 Inorganica chimica acta Vol.366 No.1

Stepwise hydrolysis of two N-(CH<SUB>2</SUB>)<SUB>2</SUB>CN groups attached to [Ni(C-racemic-L<SUP>2</SUP>)(OAc)]<SUP>+</SUP> and [Cu(C-racemic-L<SUP>2</SUP>)]<SUP>2+</SUP> (L<SUP>2</SUP>=1,8-bis(N-cyanoethyl)-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) has been investigated. The reaction of [Ni(C-meso-L<SUP>2</SUP>)]<SUP>2+</SUP> has also been examined. Interestingly, [Ni(C-racemic-L<SUP>2</SUP>)(OAc)]<SUP>+</SUP> is readily hydrolyzed to [Ni(C-racemic-L<SUP>3</SUP>)]<SUP>2+</SUP> bearing one N-(CH<SUB>2</SUB>)<SUB>2</SUB>CONH<SUB>2</SUB> and one N-(CH<SUB>2</SUB>)<SUB>2</SUB>CN pendant arms at pH @?6, whereas [Cu(C-racemic-L<SUP>2</SUP>)]<SUP>2+</SUP> and [Ni(C-meso-L<SUP>2</SUP>)]<SUP>2+</SUP> are quite inert against hydrolysis under similar acidic conditions. Although [Cu(C-racemic-L<SUP>2</SUP>)]<SUP>2+</SUP> is hydrolyzed to [Cu(C-racemic-L<SUP>3</SUP>)]<SUP>2+</SUP> at pH 9, [Ni(C-meso-L<SUP>2</SUP>)]<SUP>2+</SUP> readily undergoes C-N bond cleavage to yield [Ni(C-meso-L<SUP>1</SUP>)]<SUP>2+</SUP> (L<SUP>1</SUP>=5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) in basic aqueous solutions. The hetero-functionalized complex [Ni(C-racemic-L<SUP>3</SUP>)]<SUP>2+</SUP> undergoes hydrolysis and C-N bond cleavage at pH 9 and 13, respectively; both [Ni(C-racemic-L<SUP>4</SUP>)]<SUP>2+</SUP> bearing two N-(CH<SUB>2</SUB>)<SUB>2</SUB>CONH<SUB>2</SUB> pendant arms and [Ni(C-racemic-L<SUP>5</SUP>)]<SUP>2+</SUP> bearing one N-(CH<SUB>2</SUB>)<SUB>2</SUB>CONH<SUB>2</SUB> group can be prepared selectively by controlling pH of the solution. However, [Cu(C-racemic-L<SUP>3</SUP>)]<SUP>2+</SUP> readily undergoes C-N bond cleavage to produce [Cu(C-racemic-L<SUP>5</SUP>)]<SUP>2+</SUP> even at pH 9. Crystal structure of [Ni(C-racemic-L<SUP>3</SUP>)]<SUP>2+</SUP> shows that the complex has severely distorted trigonal bipyramidal coordination geometry. Electronic absorption spectra of [Cu(C-racemic-L<SUP>3</SUP>)]<SUP>2+</SUP>, [Ni(C-racemic-L<SUP>5</SUP>)]<SUP>2+</SUP>, and [Cu(C-racemic-L<SUP>5</SUP>)]<SUP>2+</SUP> indicate that they also have trigonal bipyramidal coordination geometry.