bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simultaneous quantification of oxysophocarpine and its active metabolite sophocarpine in rat plasma by liquid chromatography/mass spectrometry for a pharmacokinetic study
Authors: Wang Su‐Jun , Yang Min , Li Xiao‐Tian , Wang Guang‐Ji 
Published: April 2007

AbstractA sensitive, rapid and specific method for the simultaneous quantification of oxysophocarpine (OSC) and its active metabolite sophocarpine (SC) in rat plasma was developed and validated, using a liquid–liquid extraction procedure followed by liquid chromatography/electrospray ionization mass spectrometric (LC/ESI‐MS) analysis. The separation was performed on a Zorbax Extend‐C18 column (2.1 mm i.d. × 50 mm, 5 µm) with a C18 guard column using methanol–water containing 5 mm ammonium acetate (15:85, v/v) as mobile phase. Analysis was performed in selected ion monitoring (SIM) mode with an electrospray ionization (ESI) interface. [M + H]+ at m/z 263 for OSC, [M + H]+ at m/z 247 for SC and [M + H]+ at m/z 249 for matrine (internal standard) were selected as detecting ions, respectively. The method was linear in the concentration ranges 10–1000 ng/mL for OSC and 5–500 ng/mL for SC. The intra‐ and inter‐day precisions (coefficient of variation) were within 7% for both analytes. Their accuracy (relative error) ranged from −6.4 to 1.5%. The limits of detection for OSC and SC were 3 and 1.5 ng/mL, respectively. The limits of quantitation for OSC and SC were 10 and 5 ng/mL, respectively. Recoveries of both analytes were greater than 85% at the low, medium and high concentrations. Both analytes were stable during all sample storage, preparation and analytic procedures. The method was successfully applied to a pharmacokinetic study after an oral administration of OSC to rats with a dose of 15 mg/kg. Copyright © 2007 John Wiley & Sons, Ltd.
Simultaneous qualitation and quantification of four phytoecdysones in Radix Achyranthis Bidentatae by high‐performance liquid chromatography with diode array detection
Authors: Li Juan , Li Hui‐Jun , Li Ping , Qi Hui 
Published: April 2007

AbstractA high‐performance liquid chromatographic method with diode array detection was developed and validated to simultaneously identify and quantify four phytoecdysones,i.e., polypodine B (1), ecdysterone (2), 25‐R inokosterone (3) and 25‐S inokosterone (4), in Radix Achyranthis Bidentatae. The analysis was performed using a C18 column with 6% tetrahydrofuran aqueous and acetonitrile isocratic elution, and the detection was carried out by DAD at 242 nm. The identities of the analytes were determined by comparing the retention time and UV spectrum with those of reference compounds. The validation of the method included linearity, sensitivity, recovery and stability. All calibration curves of the four phytoecdysones showed good linear regression (r2 ≥ 0.9993). The limit of detection (S/N = 3) and limit of quantification (S/N = 10) were less than 7.5 and 12.3 ng, respectively. The method provided desirable repeatability with overall intra‐ and inter‐day variations of less than 4.67%. The obtained recoveries varied between 95.1 and 104.4% while the relative standard deviations were below 4.85% (n = 3). The analysis results indicated that the contents of the investigated phytoecdysones in Radix Achyranthis Bidentatae from different locations were highly variant, and the genuine crude drug indigenous to Henan province did not possess the highest concentration of phytoecdysones. Copyright © 2007 John Wiley & Sons, Ltd.
Validated LC‐MS/MS method for quantification of gabapentin in human plasma: application to pharmacokinetic and bioequivalence studies in Korean volunteers
Authors: Park Jin‐Hee , Jhee Ok‐Hwa , Park Song‐Hee , Lee Jung‐Sik , Lee Min‐Ho , Shaw Leslie M. , Kim Kwang‐Hyun , Lee Jong‐Ho , Kim Yong‐Seok , Kang Ju‐Seop 
Published: April 2007

AbstractA sensitive validated liquid chromatography–tandem mass spectrometric method (LC‐MS/MS) for gabapentin (GB) in human plasma has been developed and applied to pharmacokinetic (PK) and bioequivalence (BE) studies in human. In a randomized crossover design with a 1‐week period, each subject received a 300 mg GB capsule. The procedure involves a simple protein precipitation with acetonitrile and separated by LC with a Gemini C18 column using acetonitrile–10 mm ammonium acetate (20:80, v/v, pH 3.2) as mobile phase. The GB and internal standard [(S)‐(+)‐α‐aminocyclohexanepropionic acid hydrate] were analyzed using an LC‐API 2000 MS/MS in multiple reaction monitoring mode. The ionization was optimized using ESI(+) and selectivity was achieved using MS/MS analysis, m/z 172.0 → 154.0 and m/z 172.0 → 126.0 for GB and IS, respectively. The assay exhibited good linearity over a working range of 20–5000 ng/mL for GB in human plasma with a lower limit of quantitation of 20 ng/mL. No endogenous compounds were found to interfere with the analysis. The accuracy and precision were shown for concentrations over the standard ranges. This method was successfully applied for the PK and BE studies by analysis of blood samples taken up to 36 h after an oral dose of 300 mg of GB in 24 healthy volunteers. Copyright © 2007 John Wiley & Sons, Ltd.
Determination and pharmacokinetics of manidipine in human plasma by HPLC/ESIMS
Authors: Jing Jing , Ren Weichao , Chen Xijing , He Hui , Zhou Wei , Zhu Xuping , Sun Ya , Wang Guangji 
Published: April 2007

AbstractA sensitive HPLC/ESIMS method was established for the determination of manidipine in human plasma and pharmacokinetics study. After basified plasma with ammonia, manidipine and the internal standard (IS) (felodipine) were extracted with n‐hexane and separated on a Hypersil ODS2 column with a mobile phase of methanol–5 mm ammonium acetate solution containing 0.1% acetic acid (85:15, v/v). MS determination was performed by electrospray ionization in the selected ion monitoring mode. Manidipine was monitored at m/z 611.4 and IS at m/z 384. The assay had a calibration range from 0.2 to 20 ng/mL and a lower limit of quantification of 0.1 ng/mL. The method has been successfully applied to the pharmacokinetic study in healthy volunteers. Copyright © 2007 John Wiley & Sons, Ltd.
Liquid chromatography–tandem mass spectrometric method for determination of the anti‐inflammatory compound vicenin‐2 in the leaves of L. ericoides Mart.
Authors: Moraes Solange Leite de , Tomaz José Carlos , Lopes Norberto Peporine 
Published: April 2007

AbstractThis paper reports a rapid and sensitive method for determination of the anti‐inflammatory compound vicenin‐2 in L. ericoides Mart. using liquid chromatography–tandem mass spectrometry. Separation of the compound of interest was performed on a VP‐ODS18 (150 × 2 mm, Shimadzu, Japan) column and a pre‐column packed with GPV‐ODS C18 (5 × 2 mm, Sigma‐Aldrich, USA) with acetonitrile–water (15:85) mobile phase containing 2% acetic acid using isocratic flow at 0.5 mL/min for 2 min. Multiple‐reaction monitoring of vicenin‐2 was performed using electrospray positive ionization. The linear calibration curves were generated using a concentration range of 5–2500 ng/mL with correlation coefficients >0.99. The values of limit of detection and limit of quantitation were found to be 1 and 5 ng/mL, respectively. The method developed based on LC‐ESIMS/MS is advantageous because it permits the rapid and selective detection of vicenin‐2. Furthermore, the method can be easily applied to the routine analysis of vicenin‐2 in plant extracts using a minimal amount of sample. Copyright © 2007 John Wiley & Sons, Ltd.
Human exhaled air analytics: biomarkers of diseases
Authors: Buszewski Bogusław , Kęsy Martyna , Ligor Tomasz , Amann Anton 
Published: April 2007

AbstractOver the last few years, breath analysis for the routine monitoring of metabolic disorders has attracted a considerable amount of scientific interest, especially since breath sampling is a non‐invasive technique, totally painless and agreeable to patients. The investigation of human breath samples with various analytical methods has shown a correlation between the concentration patterns of volatile organic compounds (VOCs) and the occurrence of certain diseases. It has been demonstrated that modern analytical instruments allow the determination of many compounds found in human breath both in normal and anomalous concentrations. The composition of exhaled breath in patients with, for example, lung cancer, inflammatory lung disease, hepatic or renal dysfunction and diabetes contains valuable information. Furthermore, the detection and quantification of oxidative stress, and its monitoring during surgery based on composition of exhaled breath, have made considerable progress. This paper gives an overview of the analytical techniques used for sample collection, preconcentration and analysis of human breath composition. The diagnostic potential of different disease‐marking substances in human breath for a selection of diseases and the clinical applications of breath analysis are discussed. Copyright © 2007 John Wiley & Sons, Ltd.
QSBMR—Quantitative structure biomagnification relationships: physicochemical and structural descriptors important for the biomagnification of organochlorines and brominated flame retardants
Authors: Lundstedt‐Enkel Katrin , Lek Per M. , Lundstedt Torbjörn , Örberg Jan 
Published: April 2007

AbstractThe aim of this project is to establish models to predict the biomagnification of contaminants present in Baltic Sea biota. In this paper a quantitative model that we term QSBMR—Quantitative Structure Biomagnification Relationships is presented. This model describes the relationship between the biomagnification factors (BMFs) for several organochlorines (OCs) and brominated flame retardants (BFRs), for example, polychlorinated biphenyls (PCBs), polybrominated diphenylethers (PBDEs) and hexabromocyclododecane (HBCD), and their descriptors, for example, physico‐chemical properties and structural descriptors.The concentrations of contaminants in herring (Clupea harengus) muscle and guillemot (Uria aalge) egg from the Baltic Sea were used. The BMFs were calculated with the randomly sampled ratios (RSR) method that denotes the BMFs with a measure of the variation. In order to describe the physico‐chemical properties and chemical structures, approximately 100 descriptors for the contaminants were generated: (a), by using the software (TSAR); (b) finding log Kow values from the literature, and (c) creating binary fingerprint variables that described the position of the chlorine and bromine for the respective PCB and PBDE molecules. Partial least squares (PLS) regression was used to model the relationship between the contaminants' BMF and the descriptors and the resulting QSBMR revealed that more than 20 descriptors in combination were important for the biomagnification of OCs and BFRs between herring and guillemot.The model including all contaminants (R2X = 0.73, R2Y = 0.87 and Q2 = 0.63, three components) explained approximately as much of the variation as the model with the PCBs alone (R2X = 0.83, R2Y = 0.87 and Q2 = 0.58, two components). The model with the BFRs alone (R2X = 0.68, R2Y = 0.88 and Q2 = 0.41, two components) had a slightly lower Q2 than the model including all contaminants.For validation, a training set of seven contaminants was selected by multivariate design (MVD) and a model was established. This model was then used to predict the BMFs of the test set (seven contaminants not included in the model). The resulting R2 for the regression Observed BMF versus Predicted BMF was high (0.65). The good models showed that descriptors important for the biomagnification of OCs and BFRs had been used. These types of models will be useful for in silico predictions of the biomagnification of new, not yet investigated, compounds as an aid in risk assessments. Copyright © 2007 John Wiley & Sons, Ltd.
A “Green Route” to Propene through Selective Hydrogen Oxidation
Authors: Blank Jan Hendrik , Beckers Jurriaan , Collignon Paul F. , Clerc Frédéric , Rothenberg Gadi 
Published: April 2007

AbstractThe pros and cons of oxidative dehydrogenation of propane are outlined and a new catalytic system based on metal‐doped cerianite catalysts is introduced. These novel materials catalyze the selective combustion of hydrogen from a mixture of hydrogen, propane, and propene at 550 °C. This gives three key advantages: energy is supplied directly where needed, product separation is made easier, and the dehydrogenation equilibrium is shifted to the desired products. A set of eighteen doped cerianites was synthesized in parallel, characterized, and screened for activity, selectivity, and stability in a cyclic redox system. The best results were obtained with Ce0.89Cr0.02Fe0.09O2, Ce0.98Sn0.02O2, and Ce0.96Cu0.02Zn0.02O2, which gave 98 %, 91 %, and 98 % selectivity, respectively. Ce0.89Cr0.02Fe0.09O2 also shows excellent stability in over 120 cycles (66 h on stream at 550 °C). Importantly, these doped cerias are monophasic crystalline materials. The dopants are incorporated as solid solutions throughout the fluorite lattice. This means that these catalysts are very stable (they do not sinter during reduction) as opposed to traditional supported metal oxides. The results show that both activity and selectivity towards hydrogen combustion can be tuned (increased or decreased) by selecting the appropriate dopant. Furthermore, the trends in selectivity differ from those measured on supported oxides of the same elements, which indicates that these novel materials indeed contain unique active sites. The factors governing selectivity towards hydrogen oxidation and the nature of the active site are discussed.
Effects of Chain Length and N‐Methylation on a Cation–π Interaction in a β‐Hairpin Peptide
Authors: Hughes Robert M. , Benshoff Matthew L. , Waters Marcey L. 
Published: April 2007

AbstractThe effects of N‐methylation and chain length on a cation–π interaction have been investigated within the context of a β‐hairpin peptide. Significant enhancement of the interaction and structural stabilization of the hairpin have been observed upon Lys methylation. Thermodynamic analysis indicates an increased entropic driving force for folding upon methylation of Lys residues. Comparison of lysine to analogues ornithine (Orn) and diaminobutyric acid (Dab) indicates that lysine provides the strongest cation–π interaction and also provides the most stable β‐hairpin due to a combination of side chain–side chain interactions and β‐sheet propensities. These studies have significance for the recognition of methylated lysine in histone proteins.
Ligand Reprogramming in Dinuclear Helicate Complexes: A Consequence of Allosteric or Electrostatic Effects?
Authors: Jeffery John C. , Rice Craig R. , Harding Lindsay P. , Baylies Christian J. , Riis‐Johannessen Thomas 
Published: April 2007

AbstractThe ditopic ligand 6,6′‐bis(4‐methylthiazol‐2‐yl)‐3,3′‐([18]crown‐6)‐2,2′‐bipyridine (L1) contains both a potentially tetradentate pyridyl‐thiazole (py‐tz) N‐donor chain and an additional “external” crown ether binding site which spans the central 2,2′‐bipyridine unit. In polar solvents (MeCN, MeNO2) this ligand forms complexes with ZnII, CdII, HgII and CuI ions via coordination of the N donors to the metal ion. Reaction with both HgII and CuI ions results in the self‐assembly of dinuclear double‐stranded helicate complexes. The ligands are partitioned by rotation about the central pypy bond, such that each can coordinate to both metals as a bis‐bidentate donor ligand. With ZnII ions a single‐stranded mononuclear species is formed in which one ligand coordinates the metal ion in a planar tetradentate fashion. Reaction with CdII ions gives rise to an equilibrium between both the dinuclear double‐stranded helicate and the mononuclear species. These complexes can further coordinate s‐block metal cations via the remote crown ether O‐donor domains; a consequence of which are some remarkable changes in the binding modes of the N‐donor domains. Reaction of the HgII‐ or CdII‐containing helicate with either Ba2+ or Sr2+ ions effectively reprogrammes the ligand to form only the single‐stranded heterobinuclear complexes [MM′(L1)]4+ (M=HgII, CdII; M′=Ba2+, Sr2+), where the transition and s‐block cations reside in the N‐ and O‐donor sites, respectively. In contrast, the same ions have only a minor structural impact on the ZnII species, which already exists as a single‐stranded mononuclear complex. Similar reactions with the CdII system result in a shift in equilibrium towards the single‐stranded species, the extent of which depends on the size and charge of the s‐block cation in question. Reaction of the dicopper(I) double‐stranded helicate with Ba2+ shows that the dinuclear structure still remains intact but the pitch length is significantly increased.
Equivalent circuits for two‐state quantum systems
Authors: Civalleri Pier Paolo , Gilli Marco , Bonnin Michele 
Published: April 2007

AbstractThe development of nanocircuits designed to ultimately interact with classical electromagnetic environments demands a description of their performance in circuit terms, i.e. in terms of voltages and currents for incident, reflected and transmitted waves. A class of quantum systems which are particularly promising for applications (e.g. in spintronics) and at the same time easy to analyse and to understand physically are the two‐state systems. Here, we present equivalent circuits for a generic two‐state quantum system imbedded in a one‐port or two‐port structure guiding a linearly polarized electromagnetic wave. For the sake of concreteness we explicitly refer to a system of spin ½ particles whose magnetic moments are aligned with the axis of the guiding structure by a strong constant magnetic field; but the formalism can be easily extended to particles endowed with electric dipole moments or any other system with two degrees of freedom. Copyright © 2007 John Wiley & Sons, Ltd.
Detection of molecular particles in live cells via machine learning
Authors: Jiang Shan , Zhou Xiaobo , Kirchhausen Tom , Wong Stephen T. C. 
Published: April 2007

AbstractClathrin‐coated pits play an important role in removing proteins and lipids from the plasma membrane and transporting them to the endosomal compartment. It is, however, still unclear whether there exist “hot spots” for the formation of Clathrin‐coated pits or the pits and arrays formed randomly on the plasma membrane. To answer this question, first of all, many hundreds of individual pits need to be detected accurately and separated in live‐cell microscope movies to capture and monitor how pits and vesicles were formed. Because of the noisy background and the low contrast of the live‐cell movies, the existing image analysis methods, such as single threshold, edge detection, and morphological operation, cannot be used. Thus, this paper proposes a machine learning method, which is based on Haar features, to detect the particle's position. Results show that this method can successfully detect most of particles in the image. In order to get the accurate boundaries of these particles, several post‐processing methods are applied and signal‐to‐noise ratio analysis is also performed to rule out the weak spots. © 2007 International Society for Analytical Cytology.
Synthesis and Catalytic Activity of η1‐Allyl and η3‐Allyl, Ethyl, and Hydrido Complexes of Ruthenium–Pentamethyl[60]fullerene
Authors: Matsuo Yutaka , Uematsu Takashi , Nakamura Eiichi 
Published: April 2007

Abstractη1‐Allyl and η3‐allyl, ethyl, and hydrido ruthenium complexes of pentamethyl[60]fullerene, Ru(η5‐C60Me5)R(CO)2(R = η1‐allyl, Et, H) and Ru(η5‐C60Me5)(η3‐allyl)(CO) were synthesized by the reaction of a chlorido complex Ru(η5‐C60Me5)Cl(CO)2 with an allyl and an ethyl Grignard reagent or lithium aluminum hydride. Conversion of the η1‐allyl complex to the corresponding η3‐allyl complex and the catalytic performance of the hydrido and the chlorido complexes in the isomerization reaction of 1‐decene to internal decenes are described. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
A Diferrous Single‐Molecule Magnet
Authors: Boudalis Athanassios K. , Sanakis Yiannis , Clemente‐Juan Juan Modesto , Mari Alain , Tuchagues Jean‐Pierre 
Published: April 2007

AbstractThe diferrous complex [Fe2(acpypentO)(NCO)3] (1),(acpypentO– = the anion of 1,5‐bis[2‐pyridyl(1‐ethylimino)]pentane‐3‐ol) was studied by spectroscopic (dual‐mode X‐band EPR and 57Fe‐Mössbauer) and magnetic (AC magnetic susceptibility) techniques. Complex 1 (A. K. Boudalis et al., Inorg. Chem. 2004, 43, 1574) was previously shown to exhibit an intramolecular ferromagnetic coupling with important single‐ion anisotropies with marked differences in the single‐ion electronic parameters of the two iron sites. In this contribution, additional studies are carried out to probe its dynamic magnetic properties. Mössbauer spectra recorded at liquid helium temperatures indicate slow paramagnetic relaxation and a ground state of the system characterized by a non‐Kramers doublet with an Ising‐type anisotropy, a condition which favours single‐molecule magnet (SMM) behaviour. A frequency‐dependent out‐of‐phase signal observed below 3 K in AC susceptibility measurements is in line with such a picture. The out‐of‐phase signal, however, is relatively weak in comparison with the in‐phase signal. Dual mode X‐band EPR spectroscopy revealed characteristic signals, the analysis of which suggests inhomogeneities in the system. For some molecules, the splitting Δ0 of the non‐Kramers ground doublet is vanishingly small, which gives rise to out‐of‐phase signals in AC susceptibility measurements and magnetically split Mössbauer spectra in the absence of external magnetic fields. Other molecules, however, are characterized by a nonnegligible Δ0, which gives rise to the dual mode X‐band EPR signals. For these molecules the magnetic relaxation is fast. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Utilization of palm oil and palm products in shortenings and margarines
Authors: Nor Aini Idris , Miskandar Mat Sahri 
Published: April 2007

AbstractMarket trends have shown that manufacturers are switching from hydrogenated fats to trans acid‐free alternatives for food product formulations or preparation. Palm oil and palm products have become important raw materials in the production of solid‐fat formulations such as shortenings and margarines in view of the current trends. Palm oil is very suitable as a major component in margarines and shortenings because it is naturally semi‐solid and it can be further modified by fractionation, interesterification, hydrogenation and blending. It is high in palmitic acid (44%) and crystallizes in the β' form which is desirable in margarines and shortenings. It contains 10% essential fatty acids (linoleic acid). The roles and the applications of palm oil and palm products in various types of shortenings and margarines are discussed.
Use of palm oil for frying in comparison with other high‐stability oils
Authors: Matthäus Bertrand 
Published: April 2007

AbstractToday, palm oil and its products, mainly palm olein, belong to the most important oils used for the preparation of fried food. The reason is that the oil is relatively cheap, it is available in huge amounts, it has a high oxidative stability and results in high‐quality and tasty foods. Thus, the oil meets the demands of the consumer and the producer of fried food. The suitability of palm oil and its products for frying was widely demonstrated in many investigations, and the paper shows some examples for the comparison of palm oil with other commonly used oils. Nevertheless palm oil and its products have a decisive drawback in comparison to conventional vegetable oils like rapeseed or soybean oil, resulting from the high content of saturated fatty acids, which are unfavourable in view of health aspects. Therefore, the search for healthier oils is going on and, in the meantime, several genetically or conventionally modified vegetable oils have appeared on the market. The paper demonstrates that palm oil and its products have a similar frying performance compared to the new so‐called “high‐oleic” oils.