Genetic analyzer-dependent DNA methylation detection and its application to existing age prediction models

DNA methylation is the most promising biomarker for estimating human age. There are various methods used for analyzing DNA methylation. Among those, the SNaPshot assay-based method provides a semi-quantitative measurement of DNA methylation using capillary electrophoresis on genetic analyzers. However, DNA methylation measures produced using different types of genetic analyzers have never been compared, although differences in methylation values can directly affect age estimates. To evaluate the differences between the results generated by different genetic analyzers, we analyzed the same blood, saliva, and control methylated DNA using three genetic analyzers—the Applied Biosystems 3130, 3500, and SeqStudio—and compared the methylation values at five CpG sites: ELOVL2, FHL2, KLF14, MIR29B2C, and TRIM59. The methylation value at each of the five CpG sites decreased in the order 3130, 3500, and SeqStudio. The differences in the results produced by the different genetic analyzers resulted in significant errors when applying the 3500 and SeqStudio data to a previous age estimation model constructed using the 3130 Genetic Analyzer data. Therefore, DNA methylation measurements from 3500 and SeqStudio were corrected using the regression functions obtained by plotting the DNA methylation data of one instrument versus the other to facilitate the application of DNA methylation data from one instrument to the age prediction model based on other instruments. The age prediction accuracy obtained by applying corrected 3500 and SeqStudio data to the existing age estimation model was as high as observed in the 3130 data.     

Flame‐retardant and mechanical properties of phenolic foams toughened with polyethylene glycol phosphates

Three kinds of polyethylene glycol phosphates (PEGPs) toughening agents were synthesized by esterification of phosphorus pentoxide (P₂O₅) with polyethylene glycol and characterized by Fourier transform infrared spectra and ³¹P nuclear magnetic resonance. A series of lightweight phenolic foams toughened with different loadings of PEGPs were prepared. Optical microscopy results show that the addition of PEGPs with small molecular weight PEG improves the structural homogeneity of phenolic foams obviously. The flame retardancy of toughened phenolic foams was evaluated by using UL 94, limiting oxygen index, and cone calorimeter. The results indicate that the incorporation of PEGPs not only increases the toughness of phenolic foams but also improves their flame retardancy. Moreover, the thermal stability of PEGPs and the toughened foams was investigated by thermogravimetric analysis. Copyright © 2013 John Wiley & Sons, Ltd.     

A UFLC‐MS/MS method with a switching ionization mode for simultaneous quantitation of polygalaxanthone III,four ginsenosides and tumulosic acid in rat plasma: application to a comparative pharmacokinetic study in normal and Alzheimer's disease rats

A fast, sensitive and reliable ultra fast liquid chromatography‐tandem mass spectrometry (UFLC‐MS/MS) method has been developed and validated for simultaneous quantitation of polygalaxanthone III (POL), ginsenoside Rb1 (GRb1), ginsenoside Rd (GRd), ginsenoside Re (GRe), ginsenoside Rg1 (GRg1) and tumulosic acid (TUM) in rat plasma after oral administration of Kai‐Xin‐San, which plays an important role for the treatment of Alzheimer's disease (AD). The plasma samples were extracted by liquid–liquid extraction using ethyl acetate–isopropanol (1:1, v/v) with salidrdoside as internal standard (IS). Good chromatographic separation was achieved using gradient elution with the mobile phase consisting of methanol and 0.01% acetic acid in water. The tandem mass spectrometric detection was performed in multiple reaction monitoring mode on 4000Q UFLC‐MS/MS system with turbo ion spray source in a negative and positive switching ionization mode. The lower limits of quantification were 0.2–1.5 ng/ml for all the analytes. Both intra‐day and inter‐day precision and accuracy of analytes were well within acceptance criteria (±15%). The mean absolute extraction recoveries of analytes and IS from rat plasma were all more than 60.0%. The validated method has been successfully applied to comparing pharmacokinetic profiles of analytes in normal and AD rat plasma. The results indicated that no significant differences in pharmacokinetic parameters of GRe, GRg1 and TUM were observed between the two groups, while the absorption of POL and GRd in AD group were significantly higher than those in normal group; moreover, the GRb1 absorbed more rapidly in model group. The different characters of pharmacokinetics might be caused by pharmacological effects of the analytes. Copyright © 2013 John Wiley & Sons, Ltd.     

Thermogravimetry study of the pyrolytic characteristics and kinetics of macro-algae Macrocystis pyrifera residue

Macrocystis pyrifera is one important marine macro-algae, while its residues produced by industrial alginate extraction is a hot potato. To figure out whether its residue is suitable for pyrolysis for biofuel, the pyrolytic characteristics and kinetics of macro-algae M. pyrifera residue was investigated using thermogravimetric method from 50 to 800 °C in an inert argon atmosphere at different heating rates of 5, 10, 20, and 30 °C min^?1. The activation energy and pre-exponential factor was calculated by Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, and Popescu methods, and the kinetic mechanism was deduced by Popescu method. The results showed that the primary devolatilization stage of M. pyrifera residue can be described by Jander function $ \left(\left[ {1 - \left( {1 - \alpha } \right)^{1/3} } \right]^{2}\right) $ . The average activation energy of M. pyrifera residue was 222.4 kJ mol^?1. The results suggested that the experimental results and kinetic parameters provided useful information for the design of pyrolytic processing system using M. pyrifera residue as feedstock.     

复合酶酶解假酸浆黄酮苷抗氧化性研究

本文研究了复合酶酶解前后假酸浆提取物的抗氧化活性能力,并采用薄层色谱法(TLC)对酶解产物中总黄酮进行了分离,利用高效液相色谱-质谱联用技术对其鉴定分析。通过对DPPH自由基、羟自由基及超氧阴离子自由基清除能力实验,酶解液抗氧化性能显著高于假酸浆提取液;酶解液的薄层及HPLC-MS法初步鉴定出假酸浆中含有桑色素、二氢槲皮素和儿茶素三种黄酮。     

Optimization of mobile phase for the determination of Esomeprazole and related compounds and investigation of stress degradation by LC–MS

In this study, the objective was to investigate the degradation behavior of Esomeprazole under different recommended stress conditions according to International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use [1] by HPLC. Our research showed that the effect of mobile phase species on separation was significant for the determination of Esomeprazole and its related compounds. Successful separation of the drug from its related impurities and degradation products formed under different stress conditions was achieved using ammonium acetate buffer/ACN by a gradient elution. Compared with phosphate buffer/ACN, ammonium acetate buffer/ACN under same pH and gradient showed a great improvement in resolution due to the change of elution order. The drug was subjected to stress conditions including acidic, alkaline, oxidative, photolytic, and thermal conditions. Extensive degradation occurred in acidic and oxidative conditions, while mild degradation was observed in alkaline and photolytic conditions. Besides, it turned out the drug was extremely stable under thermal condition. The stability‐indicating LC–UV method was validated with respect to linearity, precision, accuracy, specificity, and robustness. The LC–MS method was also adopted for the characterization of degradation products. Based on the m/z values and fragmentation patterns, the degradation pathway of the drug has been proposed.     

Surface and Catalytic Properties of K/V Catalysts Coating on Porous Al2O3 Substrate

The morphology of different ratio K/V catalysts supported on porous α‐alumina substrate was investigated by atomic force microscopy (AFM). Changes in the particle size distribution, pore size distribution were analyzed respectively using AFM software. In addition, their catalytic activities and compositions for carbon oxidation were studied by x‐ray diffraction (XRD), differential scanning calorimetry (DSC), and temperature‐programmed reactions (TPR). As a result, with the increase of K concentration, the mean particle size gradually increased and the mean pore size decreased. According to the catalytic activity studies, the catalytic activity of the KVO₃ and K₃V₅O₁₄ phases are more effective than KCl.     

A pre-enrichment procedure using diethyldithiocarbamate-modified TiO2 nanoparticles for the analysis of biological and natural water samples by ICP-AES

In this article, a new method that utilizes a diethyldithiocarbamate-modified nanometre TiO₂ (TiO₂–DDTC) as solid-phase extractant has been developed for simultaneous preconcentration of trace Cu(II), Pb(II), Zn(II), and Cd(II) prior to measurement by inductively coupled plasma atomic emission spectrometry (ICP-AES). The separation/preconcentration conditions of analytes, which include the effects of pH, sample flow rate and volume, elution conditions, and interfering ions on the recovery of the analytes, were investigated. At pH 5, the adsorption capacity of modified nanometre TiO₂–DDTC was found to be 6.2, 19, 4.7, and 6.0?mg/g for Cu(II), Pb(II), Zn(II), and Cd(II), respectively. According to the definition of IUPAC, the detection limits (3σ) of this method for Cu(II), Pb(II), Zn(II), and Cd(II) were 0.41, 1.7, 0.39, and 0.52?ng/mL, respectively. The proposed method achieved satisfied results when applied to the determinations of trace Cu(II), Pb(II), Zn(II), and Cd(II) in biological and natural water samples.     

A Silyliumylidene Cation Stabilized by an Amidinate Ligand and 4‐Dimethylaminopyridine

The synthesis and reactivity of a silyliumylidene cation stabilized by an amidinate ligand and 4‐dimethylaminopyridine (DMAP) are described. The reaction of the amidinate silicon(I) dimer [ L Si:]₂ ( 1 ; L =PhC(NtBu)₂) with one equivalent of N‐trimethylsilyl‐4‐dimethylaminopyridinium triflate [4‐NMe₂C₅H₄NSiMe₃]OTf and two equivalents of DMAP in THF afforded [ L Si(DMAP)]OTf ( 2 ). The ambiphilic character of 2 is demonstrated from its reactivity. Treatment of 2 with 1 in THF afforded the disilylenylsilylium triflate [ L′ ₂( L )Si]OTf ( 3 ; L′ = L Si:) with the displacement of DMAP. The reaction of 2 with [K{HB(iBu)₃}] and elemental sulfur in THF afforded the silylsilylene [ L SiSi(H){(NtBu)₂C(H)Ph}] ( 4 ) and the base‐stabilized silanethionium triflate [ L Si(S)DMAP]OTf ( 5 ), respectively. Compounds 2 , 3 , and 5 have been characterized by X‐ray crystallography.