Methodology for and the determination of the major constituents and metabolites of the Amazonian botanical medicine ayahuasca in human urine

Ayahuasca, also known as caapi or yage among various South American groups, holds a highly esteemed and millennia-old position in these cultures' medical and religious pharmacopeia. There is now an increasing interest in the potential for modern medical applications of ayahuasca, as well as concerns regarding its increasing potential for abuse. Toxicological and clinical research to address these issues will require information regarding its metabolism and clearance. Thus, a rapid, sensitive and specific method for characterization and quantitation of the major constituents and of the metabolites of ayahuasca in urine is needed. The present research provides a protocol for conducting such analyses. The characteristics of the method, conducted by sample dilution and using HPLC-electrospray ionization (ESI)-selected reaction monitoring (SRM)-tandem mass spectrometry, are presented. The application of the analytical protocol to urine samples collected from three individuals that were administered ayahuasca has also been demonstrated. The data show that the major metabolite of the hallucinogenic component of ayahuasca, N,N-dimethyltryptamine (DMT), is the corresponding N-oxide, the first time this metabolite has been described in in vivo studies in humans. Further, very little DMT was detected in urine, despite the inhibition of monoamine oxidase afforded by the presence of the harmala alkaloids in ayahuasca. The major harmala alkaloid excreted was tetrahydroharmine. Other excretion products and metabolites were also identified and quantified. The method described would be suitable for use in further toxicological and clinical research on ayahuasca.     

Versatile grafting approaches to star-shaped POSS-containing hybrid polymers using RAFT polymerization and click chemistry

An alkyne-bearing polyhedral oligomeric silsesquioxane (POSS) core was used to prepare POSS-containing polymer hybrids using 'grafting to' or 'grafting from' strategies in combination with reversible chain transfer and click chemistry.     

Simultaneous quantitation of testosterone and estradiol in human cell line (H295R) by liquid chromatography/positive atmospheric pressure photoionization tandem mass spectrometry

The possible interaction of environmental contaminants with the endocrine system has been an environmental concern since the early 1990s. To examine these interactions test guidelines have been introduced by regulatory agencies to screen for possible endocrine active compounds. One of these guidelines is the EPA's OPPTS 890.1550 [Steroidogenesis (Human Cell Line‐H295R)]. This guideline requires the quantification of two major biomarkers (testosterone and estradiol) in various biological test systems. Traditional quantitation methodologies such as Radioimmunoassay (RIA) and Enzyme‐linked Immunosorbent Assay (ELISA) have been used to quantify low levels of steroids. However, those methodologies have drawbacks such as the radioactive safety, antibody availability, separate assay for each biomarker, and lack of selectivity. In the current study, a rapid and sensitive liquid chromatography/positive atmospheric pressure photoionization tandem mass spectrometry method (LC/APPI‐MS/MS) has been developed and validated for the simultaneous quantitation of testosterone and estradiol in the H295R cell line. Briefly, the media from cultured cells was extracted with dichloromethane (CH₂Cl₂) containing internal standards of both testosterone‐d₃ and estradiol‐¹³C₃; then, the extracted organic layer was concentrated down to dryness. The final residue was derivatized with dansyl chloride solution, and directly analyzed by LC/APPI‐MS/MS. The calibration curves, with concentration ranging from 10 to 2500 pg/mL, were linear with coefficient >0.99. The lower limits of quantitation for both testosterone and estradiol were 10 pg/mL. This method was successfully validated to support requirements of the current EPA Steroidogenesis guideline. This type of method may also provide value for rapid and precise measurements of these two hormones in other in vitro or in vivo test systems. Copyright © 2011 John Wiley & Sons, Ltd.     

Microstructural characterization of next generation nuclear graphites

This article reports the microstructural characteristics of various petroleum and pitch based nuclear graphites (IG-110, NBG-18, and PCEA) that are of interest to the next generation nuclear plant program. Bright-field transmission electron microscopy imaging was used to identify and understand the different features constituting the microstructure of nuclear graphite such as the filler particles, microcracks, binder phase, rosette-shaped quinoline insoluble (QI) particles, chaotic structures, and turbostratic graphite phase. The dimensions of microcracks were found to vary from a few nanometers to tens of microns. Furthermore, the microcracks were found to be filled with amorphous carbon of unknown origin. The pitch coke based graphite (NBG-18) was found to contain higher concentration of binder phase constituting QI particles as well as chaotic structures. The turbostratic graphite, present in all of the grades, was identified through their elliptical diffraction patterns. The difference in the microstructure has been analyzed in view of their processing conditions.     

Dual-targeting conjugates designed to improve the efficacy of radiolabeled peptides

Radiolabeled regulatory peptides are useful tools in nuclear medicine for the diagnosis (imaging) and therapy of cancer. The specificity of the peptides towards GPC receptors, which are overexpressed by cancer cells, and their favorable pharmacokinetic profile make them ideal vectors to transport conjugated radionuclides to tumors and metastases. However, after internalization of the radiopeptide into cancer cells and tumors, a rapid washout of a substantial fraction of the delivered radioactivity is often observed. This phenomenon may represent a limitation of radiopeptides for clinical applications. Here, we report the synthesis, radiolabeling, stability, and in vitro evaluation of a novel, dual-targeting peptide radioconjugate designed to enhance the cellular retention of radioactivity. The described trifunctional conjugate is comprised of a Tc-99m SPECT reporter probe, a cell membrane receptor-specific peptide, and a second targeting entity directed towards mitochondria. While the specificity of the first generation of dual-targeting conjugates towards its extracellular target was demonstrated, intracellular targeting could not be confirmed probably due to non-specific binding or hindered passage through the membrane of the organelle. The work presented describes a novel approach with potential to improve the efficacy of radiopharmaceuticals by enhancing the intracellular retention of radioactivity.     

Synthesis and characterization of homochiral cholesteryl 1-alkenesulfinate esters

A number of ,β-unsaturated sulfinyl chlorides 1 has been separately prepared and treated with (−)-cholesterol under various conditions some of which incorporated chiral amines quinine or quinidine. Some (R_S) vinylic sulfinates could be isolated in enantiopure form following one or two recrystallizations of the resulting diastereomeric mixtures of (−)-cholesteryl 1-alkenesulfinates 2. Access to diastereomerically enriched (S_S) vinylic sulfinates (66–75% de) was achieved in three instances. Absolute stereochemical assignments were made with the assistance of the chiral solvating agent (R)-2,2,2-trifluoro-1-(9-anthryl)ethanol.     

Coherent artifact in modern pulse measurements

We simulate multishot intensity-and-phase measurements of unstable trains of complex ultrashort pulses using second-harmonic-generation (SHG) frequency-resolved optical gating (FROG) and spectral-phase interferometry for direct electric-field reconstruction (SPIDER). Both techniques fail to see the pulse structure. But FROG yields the correct average pulse duration and suggests the instability by exhibiting significant disagreement between measured and retrieved traces. SPIDER retrieves the correct average spectral phase but significantly underestimates the average pulse duration. In short, SPIDER measures only the coherent artifact. An analytical calculation confirms this last fact.     

Determination of moisture content of single-wall carbon nanotubes

Several techniques were evaluated for the establishment of reliable water/moisture content of single-wall carbon nanotubes. Karl Fischer titration (KF) provides a direct measure of the water content and was used for benchmarking against results obtained by conventional oven drying, desiccation over anhydrous magnesium perchlorate as well as by thermogravimetry and prompt gamma-ray activation analysis. Agreement amongst results was satisfactory with the exception of thermogravimetry, although care must be taken with oven drying as it is possible to register mass gain after an initial moisture loss if prolonged drying time or elevated temperatures (120 °C) are used. Thermogravimetric data were precise but a bias was evident that could be accounted for by considering the non-selective loss of mass as volatile carbonaceous components. Simple drying over anhydrous magnesium perchlorate for a minimum period of 8-10 days is recommended if KF is not available for this measurement.     

Direct analysis of psychoactive tryptamine and harmala alkaloids in the Amazonian botanical medicine ayahuasca by liquid chromatography–electrospray ionization-tandem mass spectrometry

A direct injection/liquid chromatography–electrospray ionization-tandem mass spectrometry procedure has been developed for the simultaneous quantitation of 11 compounds potentially found in the increasingly popular Amazonian botanical medicine and religious sacrament ayahuasca. The method utilizes a deuterated internal standard for quantitation and affords rapid detection of the alkaloids by a simple dilution assay, requiring no extraction procedures. Further, the method demonstrates a high degree of specificity for the compounds in question, as well as low limits of detection and quantitation despite using samples for analysis that had been diluted up to 200:1. This approach also appears to eliminate potential matrix effects. Method bias for each compound, examined over a range of concentrations, was also determined as was inter- and intra-assay variation. Its application to the analysis of three different ayahuasca preparations is also described. This method should prove useful in the study of ayahuasca in clinical and ethnobotanical research as well as in forensic examinations of ayahuasca preparations.     

A second order self-consistent IMEX method for radiation hydrodynamics

We present a second order self-consistent implicit/explicit (methods that use the combination of implicit and explicit discretizations are often referred to as IMEX (implicit/explicit) methods ,  and ) time integration technique for solving radiation hydrodynamics problems. The operators of the radiation hydrodynamics are splitted as such that the hydrodynamics equations are solved explicitly making use of the capability of well-understood explicit schemes. On the other hand, the radiation diffusion part is solved implicitly. The idea of the self-consistent IMEX method is to hybridize the implicit and explicit time discretizations in a nonlinearly consistent way to achieve second order time convergent calculations. In our self-consistent IMEX method, we solve the hydrodynamics equations inside the implicit block as part of the nonlinear function evaluation making use of the Jacobian-free Newton Krylov (JFNK) method ,  and . This is done to avoid order reductions in time convergence due to the operator splitting. We present results from several test calculations in order to validate the numerical order of our scheme. For each test, we have established second order time convergence.