Enhanced matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometric analysis of bacteriophage major capsid proteins with β‐mercaptoethanol pretreatment

Bacteriophage (phage) proteins have been analyzed previously with matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS). However, analysis of phage major capsid proteins (MCPs) has been limited by the ability to reproducibly generate ions from MCP monomers. While the acidic conditions of MALDI‐TOF MS sample preparation have been shown to aid in disassembly of some phage capsids, many require further treatment to successfully liberate MCP monomers. The findings presented here suggest that β‐mercaptoethanol reduction of the disulfide bonds linking phage MCPs prior to mass spectrometric analysis results in significantly increased MALDI‐TOF MS sensitivity and reproducibility of Yersinia pestis‐specific phage protein profiles. Copyright © 2009 John Wiley & Sons, Ltd.     

Universal Central Extensions in Semi-Abelian Categories

Basing ourselves on Janelidze and Kelly’s general notion of central extension, we study universal central extensions in the context of semi-abelian categories. We consider a new fundamental condition on composition of central extensions and give examples of categories which do, or do not, satisfy this condition.     

Amycomycins C and D,new angucyclines from Kitasatospora sp.

Two new angucycline compounds containing O-glycosylated 6-deoxy-α-l-talose were isolated from Kitasatospora sp. The compounds were elucidated based on spectroscopic methods including UV, HR-ESIMS, and NMR. A feeding experiment using alizarin led to the conversion of alizarin to a monoglycosylated product with high efficiency, which allows isolation of the sugar after hydrolysis and determination of the absolute configuration of the sugar.     

Stereospecific analytical method development and preliminary in vivo pharmacokinetic characterization of pinostrobin in the rat

The complete pharmacokinetic disposition of the chiral flavonoid (±) pinostrobin remains unknown without the development of an analytical method of detection and quantitation of its individual enantiomers. Resolution of the enantiomers of pinostrobin was achieved using as simple high‐performance liquid chromatographic method. A Chiralpak® AD‐RH column was employed to perform baseline separation with UV detection at 287 nm. The standard curves were linear ranging from 0.5 to 100 µg/mL for each enantiomer. The limit of quantification was 0.5 µg/mL. Precision and accuracy of the assay was < 15% (RSD) and was with a bias <15% for all points on the calibration curve. The assay was applied successfully to stereoselective serum disposition of pinostrobin enantiomers in rats. Both enantiomers had a serum half‐life of ~7 h. They also shared similar values of volume of distribution (V_d S‐pinostrobin, 8.2 L/kg; V_d R‐pinostrobin, 8.9 L/kg), total clearance (S‐pinostrobin CL_total, 0.959 L//h/kg; R‐pinostrobin CL_total, 1.055 L//h/kg), and area under the curve (S‐pinostrobin AUC_inf, 23.16 µg h/mL; R‐pinostrobin AUC_inf, 21.296 µg h/mL). The large volume of distribution suggests extensive distribution of pinostrobin into tissues. Copyright © 2012 John Wiley & Sons, Ltd.     

Implementation of a Sequential Injection Pre-Treatment Method for Simultaneous Radium and Strontium Determination

A semi-automatic procedure for the simultaneous determination of Ra and Sr in two steps has been developed. In the first step, separation and pre-concentration of both analytes is performed by using a sequential injection procedure. In the second step, the activities of ²²⁶Ra and ⁹⁰Sr, alpha and beta emitters, respectively, are determined using a low background proportional counter at the corresponding plateau potentials. ²²⁶Ra concentration is obtained by a single measurement of the precipitate. ⁹⁰Sr activity is determined by means of its daughter ⁹⁰Y carrying out two different measurements along the first day after the separation process; the solution of the Bateman radioactivity decay equations allows to obtain the initial ⁹⁰Sr-⁹⁰Y activities. The activities analysed in the present work have been ranged between 0-14 Bq/L for ²²⁶Ra and 0-175 Bq/L for ⁹⁰Sr.     

Identification and enantioselective gas chromatographic mass-spectrometric separation of O-desmethylnaproxen,the main metabolite of the drug naproxen,as a new environmental contaminant

O-Desmethylnaproxen (2-(6-hydroxynaphthalen-2-yl)propanoic acid) was identified in 10 different water samples from Germany and Pakistan. In the Pakistan samples it was found in all samples, surface water and effluents, exhibiting estimated concentrations between 0.04 and 1.36 μg/L. In Germany it was only encountered in the STP-effluent with an average concentration of 0.23 μg/L. Furthermore, enantioselective GC analyses revealed differences in the enantiomeric ratios found in Germany and Pakistan. To the best of our knowledge this is the first report on the identification of O-desmethylnaproxen, the main metabolite of the drug naproxen, in environmental samples.     

Sol-Gel assembly of CdSe nanoparticles to form porous aerogel networks

A detailed study of CdSe aerogels prepared by oxidative aggregation of primary nanoparticles (prepared at room temperature and high temperature conditions, >250 degrees C), followed by CO2 supercritical drying, is described. The resultant materials are mesoporous, with an interconnected network of colloidal nanoparticles, and exhibit BET surface areas up to 224 m2/g and BJH average pore diameters in the range of 16-32 nm. Powder X-ray diffraction studies indicate that these materials retain the crystal structure of the primary nanoparticles, with a slight increase in primary particle size upon gelation and aerogel formation. Optical band gap measurements and photoluminescence studies show that the as-prepared aerogels retain the quantum-confined optical properties of the nanoparticle building blocks despite being connected into a 3-D network. The specific optical characteristics of the aerogel can be further modified by surface ligand exchange at the wet-gel stage, without destroying the gel network.