EarlyView Articles

Orientationally invariant metrics of apparent compartment eccentricity from double pulsed field gradient diffusion experiments

Published: Aug 23, 2013

Author(s): Sune Nørhøj Jespersen, Henrik Lundell, Casper Kaae Sønderby, Tim B. Dyrby

Journal: NMR in Biomedicine

Pulsed field gradient diffusion sequences (PFG) with multiple diffusion encoding blocks have been indicated to offer new microstructural tissue information, such as the ability to detect nonspherical compartment shapes in macroscopically isotropic samples, i.e. samples with negligible directional signal dependence on diffusion gradients in standard diffusion experiments. However, current acquisition schemes are not rotationally invariant...

Sub‐micron imaging of sub‐surface nanocrystalline structure in silicon

Published: Aug 23, 2013

Author(s): Shen Xu, Xiaoduan Tang, Yanan Yue, Xinwei Wang

Journal: Journal of Raman Spectroscopy

This work reports on a surprising and abnormal increase of the Raman intensity when the probing area is moved to the edge of a mechanically cleaved Si wafer. Our detailed surface structure study based on atomic force microscope and scanning electron microscope rules out any effect from surface morphology. Systematic study of the Raman system focusing effect with a range of µm finds no focusing effect involved in our observed phenomenon....

The resonance and pre‐resonance Raman scattering in the low energy 1 ¹ B _2u and 1 ¹ B _3u states of 1,4,5,8‐naphthalenetetracarboxy dianhydride in terms of DFT methods. The aggregation of NTCDA molecules in t

Published: Aug 23, 2013

Author(s): M. Makowski, P. Zazakowny, M. T. Pawlikowski

Journal: Journal of Raman Spectroscopy

Abstract The absorption, pre‐resonance, and resonance Raman spectra of 1,4,5,8‐naphthalenetetracarboxy dianhydride (NTCDA) molecule are examined in terms of time‐dependent density functional theory at TD‐B3LYP/aug‐cc‐pVDZ and TD‐SVWN/aug‐cc‐pVDZ levels. The Franck–Condon analysis performed for two 11Ag → 11B2u and 11Ag → 11B3u overlapping transitions leads to an excellent agreement between the theoretical predictions and experimental data...

Temperature‐induced conformational transition of bovine serum albumin in neutral aqueous solution by reversed‐phase liquid chromatography

Published: Aug 23, 2013

Author(s): Liujiao Bian, Dan Wu, Wei Hu

Journal: Biomedical Chromatography

ABSTRACT The temperature‐induced conformational transition of bovine serum albumin (BSA) in neutral aqueous solution was studied using intrinsic fluorescence emission spectrum, reversed‐phase liquid chromatography and sodium dodecyl sulfate–polyacrylamide gel electrophoresis, and the conformation transition thermodynamic parameters were determined in the temperature range 12–50 °C. The results showed that, in the temperature range...

A study of bremsstrahlung spectra and absorbed dose of beta in teeth enamel and dentin

Published: Aug 19, 2013

Author(s): H. C. Manjunatha

Journal: X-Ray Spectrometry

The beta‐induced bremsstrahlung spectra produced by 113 pure beta nuclides in teeth enamel and dentin are computed. The computed spectral distributions are presented. The spectral shapes are primarily responsible for variations in the shapes of depth‐dose distributions. They are intended to provide a quick and convenient reference for spectral shapes and to give an indication of the wide variation in these shapes. The computed...

Interrelation of ³¹ P‐MRS metabolism measurements in resting and exercised quadriceps muscle of overweight‐to‐obese sedentary individuals

Published: Aug 16, 2013

Author(s): Ladislav Valkovič, Barbara Ukropcová, Marek Chmelík, Miroslav Baláž, Wolfgang Bogner, Albrecht Ingo Schmid, Ivan Frollo, Erika Zemková, Iwar Klimeš, Jozef Ukropec, Siegfried Trattnig, Martin Krššák

Journal: NMR in Biomedicine

Phosphorus magnetic resonance spectroscopy (31P‐MRS) enables the non‐invasive evaluation of muscle metabolism. Resting Pi‐to‐ATP flux can be assessed through magnetization transfer (MT) techniques, and maximal oxidative flux (Qmax) can be calculated by monitoring of phosphocreatine (PCr) recovery after exercise. In this study, the muscle metabolism parameters of 13 overweight‐to‐obese sedentary individuals were measured with both MT and dynamic PCr...

Hyperpolarized singlet lifetimes of pyruvate in human blood and in the mouse

Published: Aug 15, 2013

Author(s): Irene Marco‐Rius, Michael C. D. Tayler, Mikko I. Kettunen, Timothy J. Larkin, Kerstin N. Timm, Eva M. Serrao, Tiago B. Rodrigues, Giuseppe Pileio, Jan Henrik Ardenkjaer‐Larsen, Malcolm H. Levitt, Kevin M. Brindle

Journal: NMR in Biomedicine

Hyperpolarized NMR is a promising technique for non‐invasive imaging of tissue metabolism in vivo. However, the pathways that can be studied are limited by the fast T1 decay of the nuclear spin order. In metabolites containing pairs of coupled nuclear spins‐1/2, the spin order may be maintained by exploiting the non‐magnetic singlet (spin‐0) state of the pair. This may allow preservation of the hyperpolarization in vivo during transport to tissues of interest,...

Case reports in forensic toxicology

Published: Aug 15, 2013

Author(s): Frank Musshoff

Journal: Drug Testing and Analysis

Monitoring the endogenous steroid profile disruption in urine and blood upon nandrolone administration: An efficient and innovative strategy to screen for nandrolone abuse in entire male horses

Published: Aug 15, 2013

Author(s): Z. Kaabia, G. Dervilly‐Pinel, M.A. Popot, L. Bailly‐Chouriberry, P. Plou, Y. Bonnaire, B. Le Bizec

Journal: Drug Testing and Analysis

Nandrolone (17β‐hydroxy‐4‐estren‐3‐one) is amongst the most misused endogenous steroid hormones in entire male horses. The detection of such a substance is challenging with regard to its endogenous presence. The current international threshold level for nandrolone misuse is based on the urinary concentration ratio of 5α‐estrane‐3β,17α‐diol (EAD) to 5(10)‐estrene‐3β,17α‐diol (EED). This ratio, however, can be influenced by a number of...

Drug laws and the 'derivative' problem

Published: Aug 15, 2013

Author(s): Leslie A. King, István Ujváry, Simon D. Brandt

Journal: Drug Testing and Analysis

The concept of a ‘derivative’ is used widely in chemistry, where its precise meaning depends on the circumstances. However, numerous examples of derivative also occur in domestic drugs legislation, some of which stem from the 1961 United Nations Single Convention on Narcotic Drugs. There is a commonly held view that only ‘first‐order’ derivatives should be considered: substances that can be created from a parent structure in a single...

Sensitive Raman spectroscopy of lipids based on drop deposition using DCDR and SERS

Published: Aug 15, 2013

Author(s): Petra Šimáková, Eva Kočišová, Marek Procházka

Journal: Journal of Raman Spectroscopy

Raman spectroscopy is widely used for study of lipids and membrane models. A severe limitation of this technique lies in the low Raman cross section requiring high sample concentrations. We report sensitive detection of synthetic 1,2‐dimyristoyl‐3‐trimethylammonium‐propane (DMTAP) lipid employing two Raman techniques with improved sensitivity: drop coating deposition Raman (DCDR) and surface‐enhanced Raman scattering (SERS)...

A high‐throughput inhibition screening of major human cytochrome P450 enzymes using an in vitro cocktail and liquid chromatography–tandem mass spectrometry

Published: Aug 15, 2013

Author(s): Chong‐Zhen Qin, Xian Ren, Zhi‐Rong Tan, Yao Chen, Ji‐Ye Yin, Jing Yu, Jian Qu, Hong‐Hao Zhou, Zhao‐Qian Liu

Journal: Biomedical Chromatography

ABSTRACT A sensitive and high‐throughput inhibition screening liquid chromatography–mass spectrometry (LC‐MS/MS) method was developed and validated for the simultaneous quantification of five probe metabolites (7‐hydroxycoumarin, CYP2A6; 4‐hydroxytolbutamide, CYP2C9; 4′‐hydroxymephenytoin, CYP2C19; α‐hydroxymetoprolol, CYP2D6; and 1‐hydroxymidazolam, CYP3A4) for in vitro cytochrome P450 activity determination in human liver microsome and...

Chiral chromatographic resolution of antiepileptic drugs and their metabolites: a challenge from the optimization to the application

Published: Aug 15, 2013

Author(s): Ana Fortuna, Gilberto Alves, Amílcar Falcão

Journal: Biomedical Chromatography

ABSTRACT A large number of the antiepileptic drugs (AEDs) presently available for clinical practice are chiral compounds while others, although achiral, may originate pharmacologically active chiral metabolites in vivo. The well‐known implications of chirality in pharmacokinetics and pharmacodynamics demand the investigation of pharmacological properties for a racemic mixture and each enantiomer. To achieve these objectives, appropriate chiral...

Application of TLC, HPLC and GC methods to the study of amino acid and peptide enantiomers: a review

Published: Aug 15, 2013

Author(s): Małgorzata Dołowy, Alina Pyka

Journal: Biomedical Chromatography

ABSTRACT Amino acids are very important organic compounds in nature. The biological activity of amino acids depends mainly on their stereoisomeric configuration (d‐ or l‐). Thus, the stereochemical analysis of amino acids and peptides is an important aspect of their characterization. Owing to the increasing role of amino acid configuration in biomedical and pharmaceutical studies, numerous analytical methods have been described in...

The effect of mobile phase composition in the enantioseparation of pharmaceutically relevant compounds with polysaccharide‐based stationary phases

Published: Aug 15, 2013

Author(s): Roccaldo Sardella, Federica Ianni, Antonella Lisanti, Maura Marinozzi, Stefania Scorzoni, Benedetto Natalini

Journal: Biomedical Chromatography

ABSTRACT Mobile phase variables have a deep influence on the chromatographic behavior with polysaccharide‐based chiral stationary phases. Basic additives are generally used to minimize peak broadening arising from unwanted interactions between polar solutes and underivatized silanols. However, basic additives can improve enantioselectivity through disruption of hydrogen bonds and modification of the polymer morphology. Acidic...

Docking and pharmacophore‐based alignment comparative molecular field analysis three‐dimensional quantitative structure–activity relationship analysis of dihydrofolate reductase inhibitors by linear and nonlinear calibration methods

Published: Aug 15, 2013

Author(s): Jahan B. Ghasemi, Nastaran Meftahi, Somayeh Pirhadi, Hossein Tavakoli

Journal: Journal of Chemometrics

Comparative molecular field analysis (CoMFA) studies have been carried out on 2,4‐diamino‐5‐(2_‐arylpropargyl)pyrimidine derivatives such as dihydrofolate reductase (DHFR) anticancer inhibitors. Because of the interoperable results of CoMFA models, they are noteworthy tools in rational drug designs. However, the huge amount of fields generated by this method contributes to its poor predictive ability. In this study, we applied a CoMFA...

Simultaneous determination of pharmaceutical components in dietary supplements for weight loss by capillary electrophoresis tandem mass spectrometry

Published: Aug 14, 2013

Author(s): Shigeki Akamatsu, Takao Mitsuhashi

Journal: Drug Testing and Analysis

A simple capillary electrophoresis tandem mass spectrometry method was developed for the simultaneous determination of 20 pharmaceutical components such as cathartics and appetite suppressants in dietary supplements for weight loss. This method allowed multidrug target screening and confirmation in differing radically in chemical structure. The separation was achieved on an uncoated fused‐silica capillary using 20 mM ammonium formate in...

Simultaneous ESI‐APCI(+) ionization and fragmentation pathways for nine benzodiazepines and zolpidem using single quadrupole LC‐MS

Published: Aug 14, 2013

Author(s): Toma Galaon, Catalina Vacaresteanu, Dan‐Florin Anghel, Victor David

Journal: Drug Testing and Analysis

Nine important 1,4‐benzodiazepines and zolpidem were characterized by liquid chromatography‐mass spectrometry using a multimode ionization source able to generate ions using both electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI), and a single quadrupole mass analyzer. An optimum chromatographic separation was applied for all target compounds in less than 8 minutes using a Zorbax Eclipse Plus column (100 x...

Quantitative MRI and ultrastructural examination of the cuprizone mouse model of demyelination

Published: Aug 13, 2013

Author(s): Jonathan D. Thiessen, Yanbo Zhang, Handi Zhang, Lingyan Wang, Richard Buist, Marc R. Del Bigio, Jiming Kong, Xin‐Min Li, Melanie Martin

Journal: NMR in Biomedicine

The cuprizone mouse model of demyelination was used to investigate the influence that white matter changes have on different magnetic resonance imaging results. In vivo T2‐weighted and magnetization transfer images (MTIs) were acquired weekly in control (n = 5) and cuprizone‐fed (n = 5) mice, with significant increases in signal intensity in T2‐weighted images (p < 0.001) and lower magnetization transfer ratio (p < 0.001) in the corpus callosum of the...

Comparison between self‐report of cannabis use and toxicological detection of THC/THCCOOH in blood and THC in oral fluid in drivers in a roadside survey

Published: Aug 13, 2013

Author(s): Trudy Van Linden, Peter Silverans, Alain G. Verstraete

Journal: Drug Testing and Analysis

Abstract The objective of this study was to compare the number of drivers who self‐reported cannabis use by questionnaires to the results of toxicological analysis. During roadside surveys, 2957 respondents driving a personal car or van completed a questionnaire to report their use of drugs and medicines during the previous two weeks and to indicate the time of their last intake. Cannabis was analyzed in oral...