Sequence- and site-specific photodissociation at 266 nm of protonated synthetic polypeptides containing a tryptophanyl residue

Oh, Joo Yeon,Moon, Jeong Hee,Kim, Myung Soo John Wiley Sons, Ltd. 2004 Rapid communications in mass spectrometry Vol.18 No.22

<P>Photodissociation at 266 nm of protonated synthetic polypeptides containing a tryptophanyl residue was investigated using a homebuilt tandem time-of-flight mass spectrometer equipped with a matrix-assisted laser desorption/ionization source. Efficient photodissociation of the protonated peptides was demonstrated. Most of the intense peaks in the laser-induced tandem mass spectra were sequence ions. Furthermore, sequence ions due to cleavages at all the peptide bonds were observed; this is a feature of the technique that is particularly useful for peptide sequencing. Fragmentations at both ends of the tryptophanyl residue were especially prevalent, which can be useful for location of the tryptophanyl chromophore in a peptide. Copyright © 2004 John Wiley & Sons, Ltd.</P>

Identification of a naturally-occurring 8-[α-D-glucopyranosyl-(1→6)-β-D-glucopyranosyl]daidzein from cultivated kudzu root

Nguyen, Van Dao,Min, Byoung-Cheol,Kyung, Myung-Ok,Park, Jong-Tae,Lee, Byong Hoon,Choi, Chung-Hyo,Seo, Nam-Seok,Kim, Yong-Ro,Ahn, Dong Uk,Lee, Sung-Joon,Park, Cheon-Seok,Kim, Jung-Wan,Park, Kwan-Hwa John Wiley Sons, Ltd. 2009 Phytochemical analysis Vol.20 No.6

<P>Introduction – Kudzu root (Radix puerariae) is a rich source of isoflavones that are effective in preventing osteoporosis, heart disease and symptoms associated with menopause. The major isoflavonoids in kudzu root extracts were reported as puerarin, daidzin and daidzein. Recently, an unknown isoflavonoid (compound 1) was detected from one-year-old kudzu root cultivated in Vietnam.</P><P>Objective – To identify a novel compound 1 in kudzu root extract and determine the structure of the compound by ESI<SUP>+</SUP> TOF MS-MS, <SUP>1</SUP>H-, <SUP>13</SUP>C-NMR and enzymatic hydrolysis.</P><P>Methodology – Samples were prepared by extraction of one-year-old kudzu root with 50% ethanol and the isoflavonoids were purified using recycling preparative HPLC. Unknown compound 1 was detected using UV-light at 254 nm in TLC and HPLC analyses. The molecular weight of 1 was determined using a TOF mass spectrometer equipped with an electrospray ion source. The structure of 1 was determined from the <SUP>13</SUP>C and <SUP>1</SUP>H NMR spectra recorded at 100.40 and 400.0 MHz, respectively.</P><P>Results – ESI<SUP>+</SUP> TOF MS-MS analysis shows that 1 is a puerarin diglycoside. The interglycosidic linkage of diglycoside determined by <SUP>1</SUP>H-, <SUP>13</SUP>C-NMR, and enzymatic hydrolysis suggests that 1 has a glucosyl residue linked to puerarin by an α-1,6-glycosidic bond. This compound is the first naturally-occurring 8-[α-D-glucopyranosyl-(1→6)-β-D-glucopyranosyl]daidzein in kudzu root. The concentration of glucosyl-α-1,6-puerarin in kudzu root was 2.3 mg/g as determined by HPLC.</P><P>Conclusion – The results indicate that puerarin diglycoside is one of the major isoflavonoids in kudzu root and has a significant impact on the preparation of highly water-soluble glycosylated puerarin. Copyright © 2009 John Wiley & Sons, Ltd.</P>

Preparative isolation of six major saponins from Platycodi Radix by high-speed counter-current chromatography

Ha, Young Wan,Kim, Yeong Shik John Wiley Sons, Ltd. 2009 Phytochemical analysis Vol.20 No.3

<B>Introduction</B><P>Platycosides, the primary constituents of Platycodi Radix, are known to have numerous and varied biological activities, exerting anti-inflammation, anti-allergy, anti-tumour, anti-obesity and anti-hyperlipidemia effects. However, effective methods for isolating and purifying platycosides from Platycodi Radix are not currently available.</P><B>Objective</B><P>To develop an efficient method for the preparative separation of six platycosides from Platycodi Radix by high-speed counter-current chromatography (HSCCC) coupled with an evaporative light scattering detection (ELSD) system.</P><B>Methodology</B><P>Preparative separation was performed by water extraction using reversed-phase C<SUB>18</SUB> column chromatography on an HSCCC-ELSD system. A two-phase solvent system comprised hexane–n-butanol–water (1:40:20, v/v) and (1:10:5, v/v) was employed. Two other key parameters, revolution speed of the separation column and flow-rate of the mobile phase, were also investigated for optimum HSCCC performance. Each peak fraction obtained from separation of the platycosides was collected according to the ELSD elution profile and determined by HPLC.</P><B>Results</B><P>Using the described method, six platycosides, all with purities of over 94%, could be isolated from 300 mg of the platycoside-enriched fraction. Their structures were characterized by electrospray ionisation mass spectrometry (ESI-MS), <SUP>1</SUP>H-NMR and <SUP>13</SUP>C-NMR.</P><B>Conclusion</B><P>Six of the main bioactive platycosides in Platycodi Radix could be isolated and purified systematically by HSCCC. Copyright © 2009 John Wiley & Sons, Ltd.</P>

A hybrid interface method for three-dimensional multiphase flows based on front tracking and level set techniques

Shin, Seungwon,Juric, Damir John Wiley Sons, Ltd. 2009 International journal for numerical methods in flu Vol.60 No.7

<P>Successful interface methods for multiphase flows need to be designed to operate well in the opposite extremes of strongly surface tension-dominant flows on the one hand and strongly deforming flows on the other. To this end, recent advances in direct numerical simulation of multiphase flows have involved the hybridization of popular methods. One hybrid approach developed by the authors is the level contour reconstruction method (LCRM), which combines the characteristics of both the front tracking and the level set method. It was designed specifically for general 3D multiphase flow problems where very dynamic and deformable interfaces interact and where accuracy, reliability, and simplicity are essential features. In this paper, we carry the hybridization of the LCRM with the level set technique to a further level in that the explicit calculation of a distance function is introduced and plays a crucial role in the interface reconstruction procedure as well as in the calculation of the surface tension force. An accurate method of computing the distance function directly from the tracked interface is presented whereby a vector distance function is found, i.e. the minimum distance to the interface as well as the corresponding minimum distance point location on the interface itself. This information allows us to calculate a compact curvature field for the computation of the surface tension force, which decreases the level of parasitic currents to a negligible level. Various benchmark test cases to demonstrate the accuracy of the new schemes compared with other existing methods are provided. Copyright © 2008 John Wiley & Sons, Ltd.</P>

A discontinuous Galerkin method for elliptic interface problems with application to electroporation

Guyomarc'h, Gré,gory,Lee, Chang-Ock,Jeon, Kiwan John Wiley Sons, Ltd. 2009 Communications in numerical methods in engineering Vol.25 No.10

<P>We solve elliptic interface problems using a discontinuous Galerkin (DG) method, for which discontinuities in the solution and in its normal derivatives are prescribed on an interface inside the domain. Standard ways to solve interface problems with finite element methods consist in enforcing the prescribed discontinuity of the solution in the finite element space. Here, we show that the DG method provides a natural framework to enforce both discontinuities weakly in the DG formulation, provided the triangulation of the domain is fitted to the interface. The resulting discretization leads to a symmetric system that can be efficiently solved with standard algorithms. The method is shown to be optimally convergent in the L<SUP>2</SUP>-norm. We apply our method to the numerical study of electroporation, a widely used medical technique with applications to gene therapy and cancer treatment. Mathematical models of electroporation involve elliptic problems with dynamic interface conditions. We discretize such problems into a sequence of elliptic interface problems that can be solved by our method. We obtain numerical results that agree with known exact solutions. Copyright © 2008 John Wiley & Sons, Ltd.</P>

Dexamethasone-conjugated polyethylenimine as an efficient gene carrier with an anti-apoptotic effect to cardiomyocytes

Kim, Hyunjung,Kim, Hyun Ah,Bae, Yun Mi,Choi, Joon Sig,Lee, Minhyung John Wiley Sons, Ltd. 2009 The journal of gene medicine Vol.11 No.6

<B>Background</B><P>Dexamethasone is a potent glucocorticoid with anti-inflammatory effects. Dexamethasone can protect ischemic cardiomyocytes from apoptosis. To apply the anti-apoptotic effect of dexamethasone to ischemic disease gene therapy, dexamethasone-conjugated polyethylenimine (PEI-Dexa) was synthesized and evaluated as an anti-apoptotic gene carrier.</P><B>Methods</B><P>PEI-Dexa was synthesized with low molecular weight polyethylenimine (PEI2K, 2 kDa). The transfection efficiency and cytotoxicity of PEI-Dexa were evaluated by luciferase assay and the MTT assay. To evaluate the anti-apoptotic effect, PEI-Dexa/DNA complex was transfected into cells and the cells were treated with H<SUB>2</SUB>O<SUB>2</SUB>. Cell viability and apoptosis level were measured by the MTT assay and caspase-3 assay, respectively.</P><B>Results</B><P>A transfection assay into H9C2 rat cardiomyocytes showed that PEI-Dexa had the highest transfection efficiency at an 8 : 1 weight ratio (PEI-Dexa/DNA). At this ratio, PEI-Dexa had higher transfection efficiency than high molecular polyethylenimine (PEI25K, 25 kDa) and PEI2K. In addition, the cytotoxicity of PEI-Dexa was lower than that of PEI25K. To evaluate the anti-apoptotic effect, PEI-Dexa/pSV-Luc or PEI2K/pSV-Luc was transfected into H9C2 cells and the cells were treated with H<SUB>2</SUB>O<SUB>2</SUB>. PEI-Dexa was found to reduce caspase-3 activity and increase cell viability compared to PEI2K. Heme oxygenase-1 (HO-1) can protect ischemic cardiomyocytes from apoptosis. Therefore, pSV-HO-1 was cloned and transfected into H9C2 cells using PEI-Dexa. The cells transfected with PEI-Dexa/pSV-HO-1 complex had lower caspase-3 activity and higher viability than the cells transfected with PEI-Dexa/pSV-Luc complex after the H<SUB>2</SUB>O<SUB>2</SUB> treatment.</P><B>Conclusions</B><P>PEI-Dexa is an efficient gene carrier with an anti-apoptotic effect and may be useful for anti-apoptotic gene therapy in combination with pSV-HO-1. Copyright © 2009 John Wiley & Sons, Ltd.</P>

Mass spectrometric analysis of the glycosphingolipid-derived glycans from miniature pig endothelial cells and islets: identification of NeuGc epitope in pig islets

Kim, Yun-Gon,Harvey, David J.,Yang, Yung-Hun,Park, Chung-Gyu,Kim, Byung-Gee John Wiley Sons, Ltd. 2009 Journal of mass spectrometry Vol.44 No.10

<P>Glycosphingolipid (GSL) is a major component of the plasma membrane in eukaryotic cells that is involved directly in a variety of immunological events via cell-to-cell or cell-to-protein interactions. In this study, qualitative and quantitative analyses of GSL-derived glycans on endothelial cells and islets from a miniature pig were performed and their glycosylation patterns were compared. A total of 60 and 47 sialylated and neutral GSL-derived glycans from the endothelial cells and islets, respectively, were characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and collision-induced fragmentation using positive-ion electrospray ionization (ESI) ion-trap tandem mass spectrometry (MS/MS). In accordance with previous immunohistochemistry studies, the α-Gal-terminated GSL was not detected but NeuGc-terminated GSLs were newly detected from miniature pig islets. In addition, the neutral GSL-derived glycans were relatively quantified by derivatization with carboxymethyl trimethylammonium hydrazide (so called Girard's T reagent) and MALDI-TOF MS. The structural information of the GSL-derived glycans from pig endothelial cells and islets suggests that special attention should be paid to all types of glycoconjugates expressed on pig tissues or cells for successful clinical xenotransplantation. Copyright © 2009 John Wiley & Sons, Ltd.</P>

Client ahead-of-time compiler for embedded Java platforms

Hong, Sunghyun,Kim, Jin-Chul,Moon, Soo-Mook,Shin, Jin Woo,Lee, Jaemok,Oh, Hyeong-Seok,Choi, Hyung-Kyu John Wiley Sons, Ltd. 2009 SOFTWARE-PRACTICE & EXPERIENCE Vol.39 No.3

<P>Many embedded Java platforms execute two types of Java classes: those installed statically on the client device and those downloaded dynamically from service providers at run time. For achieving higher performance, the static Java classes can be compiled into machine code by ahead-of-time compiler (AOTC) in the server, and the translated machine code can be installed on the client device. Unfortunately, AOTC cannot be applicable to the dynamically downloaded classes. This paper proposes client-AOTC (c-AOTC), which performs AOTC on the client device using the just-in-time compiler (JITC) module installed on the device, obviating the JITC overhead and complementing the server-AOTC. The machine code of a method translated by JITC is cached on a persistent memory of the device, and when the method is invoked again in a later run of the program, the machine code is loaded and executed directly without any translation overhead. A major issue in c-AOTC is relocation because some of the address constants embedded in the cached machine code are not correct when the machine code is loaded and used in a different run; those addresses should be corrected before they are used. Constant pool resolution and inlining complicate the relocation problem, and we propose our solutions. The persistent memory overhead for saving the relocation information is also an issue, and we propose a technique to encode the relocation information and compress the machine code efficiently. We developed a c-AOTC on Sun's CDC VM reference implementation, and our evaluation results indicate that c-AOTC can improve the performance significantly, as much as an average of 12% for EEMBC and 4% for SpecJVM98, with a persistent memory overhead of 1% on average. Copyright © 2008 John Wiley & Sons, Ltd.</P>

Performance analysis of APSK modulation for DVB-S2 transmission over nonlinear channels

Sung, Wonjin,Kang, Seokheon,Kim, Pansoo,Chang, Dae-Ig,Shin, Dong-Joon John Wiley Sons, Ltd. 2009 International journal of satellite communications Vol.27 No.6

<P>For increased bandwidth efficiency and receiver performance, standards for satellite broadcasting systems are evolving by utilizing efficient transmission techniques. The second-generation digital video broadcasting for satellites (DVB-S2) adopts the amplitude phase shift keying (APSK) modulation for enhanced performance over nonlinear channels. In this paper, we derive error rate bounds for APSK modulated symbols and generalize the bounds to the case of distorted constellation, which occurs when the maximum transmission amplitude is saturated by the soft-limiter type channel. The derived bound is shown to significantly improve the previously known result, to accurately predict both the symbol error rate and bit error rate in the entire signal-to-noise ratio (SNR) region of interest. Using the derived formula, the optimal input power level for the soft-limiter channel is determined, and the corresponding minimal error rates for 16- and 32-APSK are quantified. The result is also interpreted in terms of optimal input back-off (IBO) for nonlinear power amplifiers by evaluating the performance degradation as a function of IBO. Copyright © 2009 John Wiley & Sons, Ltd.</P>

Kinetics and mechanism of the aminolysis of dimethyl and methyl phenyl phosphinic chlorides with anilines

Dey, Nilay Kumar,Hoque, Md. Ehtesham Ul,Kim, Chan Kyung,Lee, Bon-Su,Lee, Hai Whang John Wiley Sons, Ltd. 2009 Journal of physical organic chemistry Vol.22 No.5

<P>The reactions of dimethyl phosphinic chloride (1) and methyl phenyl phosphinic chloride (2) with X-anilines have been studied kinetically in acetonitrile at 15.0 and 55.0 °C, respectively. The deuterium kinetic isotope effects (KIEs) involving deuterated aniline nucleophiles (XC<SUB>6</SUB>H<SUB>4</SUB>ND<SUB>2</SUB>) are also reported for the same reactions. The obtained KIEs for 1 are secondary inverse (k<SUB>H</SUB>/k<SUB>D</SUB> = 0.703–0.899 < 1), while those for 2 are primary normal (k<SUB>H</SUB>/k<SUB>D</SUB> = 1.62–2.10 > 1). A concerted mechanism involving predominantly backside nucleophilic attack is proposed for the anilinolysis of 1. A concerted mechanism involving predominantly frontside attack via a hydrogen-bonded four-center-type transition state is proposed for the anilinolysis of 2. The degree of steric hindrance is the major factor that determines both the reactivity of the phosphinates and the direction of the nucleophilic attack on the phosphinates. Copyright © 2008 John Wiley & Sons, Ltd.</P> <B>Graphic Abstract</B> <P>Phosphoryl transfer reactions are known to proceed via two main types of mechanisms: a stepwise mechanism involving a trigonal bipyramidal pentacoordinate (TBP-5C) intermediate and a concerted mechanism via a single TBP-5C transition state (TS). When the nucleophile attacks the reaction center from the side opposite the leaving group (backside attack), the configuration is inversed. However, when the nucleophile attacks from the leaving group side (frontside attack), the configuration is retained. <img src='wiley_img/08943230-2009-22-5-POC1478-gra001.gif' alt='wiley_img/08943230-2009-22-5-POC1478-gra001'> </P>