Medical Library

A new rapid micro-method for the molecular-chemical characterization of rhizodeposits by field-ionization mass spectrometry.

Time-consuming investigation of rhizodeposit composition by leaching, freeze-drying of leachate, and pyrolysis-field ionization mass spectrometry (Py-FIMS) of solid samples was replaced by direct Py-FIMS of a 5 microL liquid rhizodeposit sample which was evaporated overnight in the quartz tube of a mass spectrometer inlet system. Application of this new rapid technique to a set of 14 liquid rhizodeposit samples from maize (Zea mays L.), leached twice with a time lag of 80 min, unequivocally showed the effect of soil texture on the chemical composition of the rhizodeposits. Irrespective of leaching time, a partial least-squares analysis separated the Py-FI mass spectra of the maize rhizodeposits leached from a soil from those leached from a soil + quartz sand-mixture (prepared by addition of 50% w/w quartz sand to the original soil). The signals which had the strongest discrimination power and were significantly enriched in leachates from the soil + quartz sand were assigned to sugars, peptides and polyamines. Mass signals of putrescine and cadaverine, a priori not expected in the rhizodeposits, were indicators of modified root environment and rhizosphere processes in the soil + quartz sand. In conclusion, the new rapid mass spectrometric profiling method is suitable for rhizosphere research because it requires very small sample volumes, is fast and highly sensitive to detect and quantify a wide range of a priori expected and unexpected organic substances. Copyright (c) 2008 John Wiley & Sons, Ltd.

Leinweber P, Eckhardt KU, Fischer H, Kuzyakov Y.

Institute for Land Use, University of Rostock, Justus‐von‐Liebig‐Weg 6, 18051 Rostock, Germany.

Investigation of volatile biomarkers in liver cancer blood using solid-phase microextraction and gas chromatography/mass spectrometry.

Solid-phase microextraction (SPME) followed by gas chromatography/mass spectrometry (GC/MS) was used for the detection of liver cancer volatile biomarkers. Headspace SPME conditions (fiber coating, extraction temperature and extraction time) and desorption conditions were optimized and applied to the determination of volatiles in human blood. Between the liver cancer group (n = 19) and the normal group (n = 18), positive rates of 19 volatile compounds among the total of 47 detected were found to be different with statistical significance (p < 0.05, chi-squared test). We suggested hexanal, 1-octen-3-ol and octane, of the 19 compounds, as biomarkers of liver cancer with clinical diagnostic value. The sensitivity and specificity of 94.7% and 100% for hexanal, 84.2% and 100% for 1-octen-3-ol, and 89.5% and 100% for octane were obtained, respectively, after the cutoff values had been properly established. These results show that SPME-GC/MS is a simple, rapid and sensitive method for the investigation of volatile disease markers in human blood. Copyright (c) 2008 John Wiley & Sons, Ltd.

Xue R, Dong L, Zhang S, Deng C, Liu T, Wang J, Shen X.

Zhongshan Hospital, Shanghai Medical College, Fudan University, Shanghai 200032, China.

PeakSelect: preprocessing tandem mass spectra for better peptide identification.

We present a new preprocessing method, PeakSelect, to improve the accuracy and efficiency of Tandem Mass-Spec peptide (protein) identification. The fundamental difference between noise and fragment ions in spectra is that ions have isotopes but noise does not. We propose a new and important concept of an Isotope Pattern Vector (IPV) which characterizes the isotope cluster of fragment ions. Then the noise and real peaks can be distinguished by the quantitative IPV values. PeakSelect first uses a new method of the Gaussian Mixture Model and Expectation-Maximization (EM) algorithm to find the base intensity level (baseline) in a spectrum. Then PeakSelect selects features based on the IPV and baseline, and constructs a decision tree to automatically classify the peaks into different categories such as noise, single ion peaks, and overlapping peaks. Experiments show that PeakSelect can help to reduce the Mascot searching time and increase the reliability of peptide identifications. In particular, PeakSelect performs well on complex spectra with a large number of peaks from large peptides, and supports more sequence identification than other well-known systems. Copyright (c) 2008 John Wiley & Sons, Ltd.

Zhang J, He S, Ling CX, Cao X, Zeng R, Gao W.

Institute of Computing Technology, Chinese Academy of Sciences, Beijing 100080, China.

Pharmacokinetics of dihydroartemisinin in Artekin tablets for single and repeated dosing in Chinese healthy volunteers.

Aim. To study the pharmacokinetics of dihydroartemisinin (DHA) in Artekin (compound dihydroartemisinin) tablets in Chinese healthy volunteers. Methods. Eighteen healthy volunteers (9 males, 9 females) received Artekin tablets for oral administration. The plasma samples of DHA were analysed by liquid-liquid extraction and determined by HPLC/ESI/MS. Results. The plasma DHA concentration-time curves of single dose and repeated doses of DHA were fitted to a two-compartment open model. The mean pharmacokinetic parameters of DHA in a single dose were: t(1/2(beta))=1.245 +/- 0.495 h, C(max)=243.6 +/- 56.15 microg/l, AUC(0 –> infinity)=450 +/- 69 h x microg/l, V(d)=5.75 +/- 2.2 l/kg and Cl=3.245 +/- 0.38 l/h/kg, while in repeated doses they were: t(1/2(beta))=1.085 +/- 0.298 h, AUC(0 –> infinity)=444.35 +/- 80.43 h x ng/ml, V(d)=4.62 +/- 1.128 ml/kg, Cl=3.0125 +/- 0.875 ml/h/kg, respectively. Conclusion. The study showed that DHA in Artekin was rapidly absorbed, distributed and eliminated in the healthy subjects. The pharmacokinetic properties of DHA in Artekin were not affected by gender in a single dose. While in repeated doses accumulation of DHA did not appear after repeated doses. Copyright (c) 2008 John Wiley & Sons, Ltd.

Hong X, Liu CH, Huang XT, Huang TL, Ye SM, Ou WP, Wang NS, Mi SQ.

Institute of Clinical Pharmacology, Guangzhou University of Chinese Medicine, Jichang Road 12, Guangzhou 510405, Guangdong Province, P. R. China.

Preview: Chem. Eur. J. 11/2008.

Homoleptic Copper(I) Arylthiolates as a New Class of p-Type Charge Carriers: Structures and Charge Mobility Studies.

Polymeric homoleptic copper(I) arylthiolates [Cu(p-SC(6)H(4)-X)](infinity) (X=CH(3) (1), H (2), CH(3)O (3), tBu (4), CF(3) (5), NO(2) (6), and COOH (7)) have been prepared as insoluble crystalline solids in good yields (75-95 %). Structure determinations by powder X-ray diffraction analysis have revealed that 1-3 and 6 form polymers of infinite chain length, with the copper atoms bridged by arylthiolate ligands. Weak intra-chain pipi stacking interactions are present in 1-3, as evidenced by the distances (3.210 A in 1, 3.016 A in 2, 3.401 A in 3) between the mean planes of neighboring phenyl rings. In the structure of 6, the intra-chain pipi interactions (d=3.711 A) are insignificant and the chain polymers are associated through weak, non-covalent C–HO hydrogen-bonding interactions (d=2.586 A). Samples of 1-7 in their polycrystalline forms proved to be thermally stable at 200-300 degrees C; their respective decomposition temperatures are around 100 degrees C higher than that of the aliphatic analogue [Cu(SCH(3))](infinity). Data from in situ variable-temperature X-ray diffractometry measurements indicated that the structures of both 1 and 7 are thermally more robust than that of [Cu(SCH(3))](infinity). TEM analysis revealed that the solid samples of 1-5 and [Cu(SCH(3))](infinity) contained homogeneously dispersed crystalline nanorods with widths of 20-250 nm, whereas smaller plate-like nanocrystals were found for 6 and 7. SAED data showed that the chain polymers of 1-3 and [Cu(SCH(3))](infinity) similarly extend along the long axes of their nanorods. The nanorods of 1-5 and [Cu(SCH(3))](infinity) have been found to exhibit p-type field-effect transistor behavior, with charge mobility (mu) values of 10(-2)-10(-5) cm(2) V(-1) s(-1). Polycrystalline solid samples of 6 and 7 each showed a low charge mobility (<10(-6) cm(2) V(-1) s(-1)). The charge mobility values of field-effect transistors made from crystalline nanorods of 1-3 and [Cu(SCH(3))](infinity) could be correlated with their unique chain-like copper-sulfur networks, with the para-substituent of the arylthiolate ligand influencing the charge-transport properties.

Che CM, Li CH, Chui SS, Roy VA, Low KH.

Coordination Chemistry Institute and the State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, P.R. China.

Spotlights on our sister journals: Chem. Eur. J. 10/2008.

Dielectrophoretic Trapping of DNA Origami.

Kuzyk A, Yurke B, Toppari JJ, Linko V, Törmä P.

Nanoscience Center, Department of Physics, University of Jyväskylä, P.O. Box 35, FIN-40014 (Finland).

Surface Functionalized Carbogenic Quantum Dots.

Bourlinos AB, Stassinopoulos A, Anglos D, Zboril R, Karakassides M, Giannelis EP.

Institute of Materials Science, NCSR “Demokritos” Ag. Paraskevi Attikis, Athens 15310 (Greece).

Sequence-Addressable DNA Logic.

Voelcker NH, Guckian KM, Saghatelian A, Ghadiri MR.

Departments of Chemistry and Molecular Biology and The Skaggs Institute for Chemical Biology The Scripps Research Institute 10550 North Torrey Pines Road La Jolla, CA 92037 (USA).