Search

We present a methodology for solution reproducibility for the Energy Exascale Earth System Model during its ongoing software infrastructure development to prepare for exascale computers. The nonlinear chaotic nature of climate system simulations precludes traditional model verification approaches since machine precision differences—resulting from code refactoring, changes in software environment, and so on—grow exponentially to a different weather state. Here, we leverage the nature of climate as a statistical description of the atmosphere in order to establish model reproducibility. We evaluate the degree to which two-sample equality of distribution tests can confidently detect the change in climate from minor tuning parameter changes on model output variables in order to establish the level of difference that indicates a new climate. To apply this (baselined test), we target a section of the model’s development cycle wherein no intentional science changes have been applied to its source code. We compare an ensemble of short simulations that were conducted using a verified model configuration against a new ensemble with the same configuration but with the latest software infrastructure (Common Infrastructure for Modeling the Earth, CIME5.0), compiler versions, and software libraries. We also compare these against ensemble simulations conducted using the original version of the software infrastructure (CIME4.0) of the earlier model configuration, but with the latest compilers and software libraries, to test the impact of new compilers and libraries in isolation from additional software infrastructure. The two-sample equality of distribution tests indicates that these ensembles indeed represent the same climate.

Synthetic Aperture Radar (SAR), with its capability of imaging day or night, ability to penetrate dense cloud cover, and suitability for interferometry, is a robust dataset for event/change monitoring. SAR data can be used to inform decision makers dealing with natural and anthropogenic hazards such as floods, earthquakes, deforestation and glacier movement. However, SAR data has only recently become freely available with global coverage, and requires complex processing with specialized software to generate analysis-ready datasets. Furthermore, processing SAR is often resource-intensive, in terms of computing power and memory, and the sheer volume of data available for processing can be overwhelming. For example, ESA's Sentinel-1 has produced ~10PB of data since launch in 2014. Even subsetting the data to a small scientific area of interest can result in many thousands of scenes, which must be processed into an analysis-ready format.The Alaska Satellite Facility (ASF) Hybrid Pluggable Processing Pipeline (HyP3), which is now out of beta and available to the public, provides custom, on-demand processing of Sentinel-1 SAR data at no cost to users. HyP3 is integrated directly into Vertex, ASF's primary data discovery tool, so users can easily select an area of interest on the Earth, find available SAR products, and click a button to send them (individually, or as a batch) to HyP3 for Radiometric Terrain Correction (RTC), Interferometric SAR (InSAR), or Change Detection processing. Processing leverages AWS cloud computing and is done in parallel for rapid product generation. Each process provides options to customize the processing and final output products, and provides metadata-rich, analysis-ready final products to users.In addition to the Vertex user interface, HyP3 provides a RESTful API and a python software developers kit (SDK) to allow programmatic access and the ability to build HyP3 into user workflows. HyP3 is open source and designed to allow users to develop new processing plugins or stand up their own custom processing pipeline.We will present an overview of using HyP3, both inside Vertex and programmatically, and the available output products. We will demonstrate using HyP3 to investigate the consequences of natural hazards and very briefly discuss the technologies and software design principles used in the development of HyP3 and how users could contribute new plugins, or stand up their own custom processing pipeline.

To address the pressing need to better understand the behavior and complex interaction of ice sheets within the global Earth system, significant development of continental-scale, dynamical ice sheet models is underway. Concurrent to the development of the Community Ice Sheet Model (CISM), the corresponding verification and validation (V&V) process is being coordinated through a new, robust, Python-based extensible software package, the Land Ice Verification and Validation toolkit (LIVVkit). Incorporated into the typical ice sheet model development cycle, it provides robust and automated numerical verification, software verification, performance validation, and physical validation analyses on a variety of platforms, from personal laptops to the largest supercomputers. LIVVkit operates on sets of regression test and reference data sets, and provides comparisons for a suite of community prioritized tests, including configuration and parameter variations, bit-for-bit evaluation, and plots of model variables to indicate where differences occur. LIVVkit also provides an easily extensible framework to incorporate and analyze results of new intercomparison projects, new observation data, and new computing platforms. LIVVkit is designed for quick adaptation to additional ice sheet models via abstraction of model specific code, functions, and configurations into an ice sheet model description bundle outside the main LIVVkit structure. Ultimately, through shareable and accessible analysis output, LIVVkit is intended to help developers build confidence in their models and enhance the credibility of ice sheet models overall.

Effective utilization of novel hybrid architectures of pre-exascale and exascale machines requires transformations to global climate modeling systems that may not reproduce the original model solution bit-for-bit. Round-off level differences grow rapidly in these non-linear and chaotic systems. This makes it difficult to isolate bugs/errors from innocuous growth expected from round-off level differences. Here, we apply two modern multivariate two sample equality of distribution tests to evaluate statistical reproducibility of global climate model simulations using standard monthly output of short (~ 1-year) simulation ensembles of a control model and a modified model of US Department of Energy's Energy Exascale Earth System Model (E3SM). Both the tests are able to identify changes induced by modifications to some model tuning parameters. We also conduct formal power analyses of the tests by applying them on designed suites of short simulation ensembles each with an increasingly different climate from the control ensemble. The results are compared against those from another such test. These power analyses provide a framework to quantify the degree of differences that can be detected confidently by the tests for a given ensemble size (sample size). This will allow model developers using the tests to make an informed decision when accepting/rejecting an unintentional non-bit-for-bit change to the model solution.

Post-print RATIONALE: Drug overdose deaths due to fentanyls and other novel psychoactive substances (NPS) are on the rise. The higher potencies of fentanyl analogs compared with morphine require new technologies to identify and quantitate NPS. METHODS: Paper spray tandem mass spectrometry and high-resolution mass spectrometry were used to identify and measure fentanyl analogs as well as common drugs of abuse in urine samples from substance use disorder clinics. Ten-microliter urine samples were deposited directly on paper spray cartridges previously loaded with internal standards, dried, and analyzed with no other sample treatment. Quantitative results were obtained using tandem mass spectrometry (MS/MS). Individual drugs were identified using high resolution accurate mass spectrometry (HRAM), and confirmed by data dependent MS/MS. RESULTS: Calibration curves in urine were linear over a range of 0.5 - 50 ng/mL with R2 of 0.99 or better for eight representative fentanyl analogs. Cartridges preloaded with internal standards demonstrated satisfactory quantitative results compared with LC/MS. Direct identification and confirmation of fentanyl analogs and other common drugs of abuse in urine using high resolution accurate mass and MS/MS fragmentation were demonstrated at low picogram levels. CONCLUSIONS: Paper spray mass spectrometry can reliably identify and quantitate fentanyl analogs and other drugs of abuse in urine. Using paper spray cartridges as collection devices reduces exposure and transportation risks associated with biological fluids. Cartridges pre-loaded with labeled internal standards can be effective for targeted screening of fentanyl analogs and other drugs of abuse. Chris Gill would like to acknowledge the Natural Sciences and Engineering Research Council of Canada (NSERC) for funding under the Discovery Grants program (RGPIN-2016-05380), Vancouver Island University for their ongoing support of my research program, and an anonymous Vancouver Island University Foundation donor who funded the necessary travel to facilitate this timely collaboration. Post-print version This is the peer reviewed version of the following article: Kennedy, J.H., Palaty, J., Gill, C.G., & Wiseman, J.M. (2018). Rapid analysis of fentanyls and other novel psychoactive substances (NPS) in substance use disorder patient urine using paper spray mass spectrometry. Rapid Communications in Mass Spectrometry, 32(15), 1280-1286. DOI: 10.1002/rcm.8164, which has been published in final form at http://dx.doi.org/10.1002/rcm.8164. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. https://viurrspace.ca/bitstream/handle/10613/12782/Gill.RCM2018.pdf?sequence=4

Earlier large-scale Greenland ice sheet sea-level projections (e.g. those run during the ice2sea and SeaRISE initiatives) have shown that ice sheet initial conditions have a large effect on the projections and give rise to important uncertainties. The goal of this initMIP-Greenland intercomparison exercise is to compare, evaluate, and improve the initialisation techniques used in the ice sheet modelling community and to estimate the associated uncertainties in modelled mass changes. initMIP-Greenland is the first in a series of ice sheet model intercomparison activities within ISMIP6 (the Ice Sheet Model Intercomparison Project for CMIP6), which is the primary activity within the Coupled Model Intercomparison Project Phase 6 (CMIP6) focusing on the ice sheets. Two experiments for the large-scale Greenland ice sheet have been designed to allow intercomparison between participating models of (1) the initial present-day state of the ice sheet and (2) the response in two idealised forward experiments. The forward experiments serve to evaluate the initialisation in terms of model drift (forward run without additional forcing) and in response to a large perturbation (prescribed surface mass balance anomaly); they should not be interpreted as sea-level projections. We present and discuss results that highlight the diversity of data sets, boundary conditions, and initialisation techniques used in the community to generate initial states of the Greenland ice sheet. We find good agreement across the ensemble for the dynamic response to surface mass balance changes in areas where the simulated ice sheets overlap but differences arising from the initial size of the ice sheet. The model drift in the control experiment is reduced for models that participated in earlier intercomparison exercises.

The observable microstructures in ice are the result of many dynamic and competing processes. These processes are influenced by climate variables in the firn. Layers deposited in different climate regimes may show variations in fabric which can persist deep into the ice sheet; fabric may `remember' these past climate regimes. We model the evolution of fabric variations below the firn-ice transition and show that the addition of shear to compressive-stress regimes preserves the modeled fabric variations longer than compression-only regimes because shear drives a positive feedback between crystal rotation and deformation. Even without shear, the modeled ice retains memory of the fabric variation for $\approx 200 \unit{ka}$ in typical polar ice-sheet conditions. Our model shows that temperature affects how long the fabric variation is preserved, but only affects the strain-integrated fabric evolution profile when comparing results straddling the thermal-activation-energy threshold ($\approx -10 \degr \unit{C}$). Even at high temperatures, migration recrystallization doesn't eliminate the modeled fabric's memory under most conditions. High levels of nearest-neighbor interactions will, however, eliminate the modeled fabric's memory more quickly than low levels of nearest-neighbor interactions. Ultimately, our model predicts that fabrics will retain memory of past climatic variations when subject to a wide variety of conditions more » found in polar ice sheets. « less

RATIONALE Trace levels of bis(2,4-di-tert-butylphenyl)phosphate (BdtbPP) leaching from single-use bioreactors (SUBs) were recently found to be highly detrimental to mammalian cell growth. The traditional approach to detect the leachable requires time-consuming solvent extraction of SUBs. To assist the qualification of SUBs and/or their manufacturing raw materials in biopharmaceutical development and manufacturing, it is essential to develop a rapid and sensitive analytical approach for detecting this leachable and related compounds, which is described in this study. METHODS Native films from several commercially available SUBs were directly examined by desorption electrospray ionization (DESI) time-of-flight mass spectrometry (TOFMS) without sample preparation. As a comparison, the same SUBs were also analyzed by high-performance liquid chromatography (HPLC)/ultraviolet (UV) following the solvent extraction. RESULTS With a suitable spray solvent selected in this study, DESI-TOFMS enabled rapid and sensitive detection of leachable compounds directly from SUBs. Accurate mass measurement from TOFMS allowed ready identification of BdtbPP, its parent analog compound, and other polymer components in the SUBs from their protonated surrogates. The relative abundances of BdtbPP in different SUBs measured by DESI-TOFMS exhibited good correlation with those from the traditional extraction-based approach with HPLC/UV. CONCLUSIONS A rapid and sensitive approach was developed for direct detection of BdtbPP and other leachables from SUBs using DESI-TOFMS. The results are in high accordance with those from conventional approaches, which indicates the usefulness of the proposed method as a qualification tool for SUBs in biopharmaceutical development and also its great potential in the analysis of extractables/leachables in a wide variety of materials, process components, devices and containers used in the pharmaceutical industry. Copyright © 2014 John Wiley & Sons, Ltd.

Direct analysis of silica C(18)-coated solid-phase microextraction (SPME) fibers using desorption electrospray ionization mass spectrometry (DESI-MS) for the purpose of analyzing drugs from raw urine is presented. The method combines a simple, inexpensive, and solvent-less sample preparation technique with the specificity and speed of DESI-MS and MS/MS. Extraction of seven drugs from raw urine is performed using specially designed SPME fibers coated uniformly with silica-C(18) stationary phase. Each SPME device is inserted into unprocessed urine under gentle agitation and, then, removed, rinsed, and analyzed directly by DESI-MS (MS/MS). Rapid screening over a wide mass range is afforded by coupling the method with a time of flight (TOF) mass spectrometer while quantitative analysis is performed using selected reaction monitoring (SRM) using a triple quadrupole mass spectrometer. The performance of the SPME DESI-MS/MS method was evaluated by preparing calibration standards and quality control (QC) samples of the seven drug compounds from urine over a range from 20 to 1000 ng/mL, with the exception of meprobamate which was prepared from 200 to 10000 ng/mL. The calibration curves constructed for each analyte had an R(2)0.99. The range of precision (%CV) and accuracy values (% bias) for low QC samples was 1-11% and 3-38%, respectively. Precision and accuracy values for high QC samples range from 0.9 to 8% and -31 to -8%. Results from urine specimens of actual exposure to drugs screened using the SPME DESI-MS/MS method showed good agreement with the conventional immunoassays and GC/MS analysis. Liquid desorption of the SPME fiber followed by LC/MS/MS also showed good agreement with the SPME DESI-MS/MS method.

The present work describes the methodology and investigates the performance of desorption electrospray ionization (DESI) combined with a triple quadrupole mass spectrometer for the quantitation of small drug molecules in human plasma. Amoxepine, atenolol, carbamazepine, clozapine, prazosin, propranolol and verapamil were selected as target analytes while terfenadine was selected as the internal standard common to each of the analytes. Protein precipitation of human plasma using acetonitrile was utilized for all samples. Limits of detection were determined for all analytes in plasma and shown to be in the range 0.2-40 ng/mL. Quantitative analysis of amoxepine, prazosin and verapamil was performed over the range 20-7400 ng/mL and shown to be linear in all cases with R(2) >0.99. In most cases, the precision (relative standard deviation) and accuracy (relative error) of each method were less than or equal to 20%, respectively. The performance of the combined techniques made it possible to analyze each sample in 15 s illustrating DESI tandem mass spectrometry (MS/MS) as powerful tool for the quantitation of analytes in deproteinized human plasma.

This study demonstrates the increased versatility of the Chiralcel OJ-H stationary phase when using various alcohol/acetonitrile mobile phases. This chiral stationary phase has traditionally been employed in the normal phase mode and more recently with neat alcohols as eluents. Selected isomeric human mineralocorticoid receptor (hMR) antagonist pharmaceutical candidates and synthetic intermediates were separated using the Chiralcel OJ-H HPLC column with novel polar cosolvent eluent systems. The capacity factors, resolution, and selectivity of the chiral separations were assessed while varying the alcohol/acetonitrile composition and alcohol identity. The mixed polar eluents provide separations that are nearly always superior to both the traditional hexane-rich and single-alcohol "polar organic" eluents for the compounds tested in this article.

As part of a program aimed at the design of conformationally constrained analogs of glutamic acid, (+)-2-aminobicyclo[3.1.0]hexane-2,6-carboxylic acid (1), identified as a highly potent, selective, group II metabotropic glutamate receptor agonist has been synthesized and studied clinically. Heterocyclic analogs of 1 were subsequently synthesized in which the C-2 methylene has been replaced by an oxygen atom (2) or a sulfur atom (3). C-14 labeled isotopomers of 1, 2 and 3 have been synthesized to facilitate pre-clinical ADME studies. A tritium labeled isotopomer of 1 was also synthesized for use in in vitro experiments. A stable labeled isotopomer of rac-1 was prepared for use as an internal standard for bioanalytical assays. The key step in each of these syntheses was the reaction of chiral ketone 4, 5 or 6 with K14CN/(NH4)2CO3 using the Bucherer–Berg protocol. In the preparation of the stable labeled isotopomer, rac-4-[13C2] was prepared in two steps from ethyl bromoacetate-[UL-13C2]; subsequent reaction of rac-4-[13C2] with K13CN/15NH4Cl/Na2CO3, followed by hydrolysis of the hydantoin yielded rac-1-[13C3,15N]. Copyright © 2005 John Wiley & Sons, Ltd.

Cryptophycin 52 is a synthetic derivative of Cryptophycin 1, a potent antimicrotubule agent isolated from cyanobacteria. In an effort to increase the potency and water solubility of the molecule, a structure-activity relationship study (SAR) was initiated around the phenyl ring of fragment A. These Cryptophycin 52 analogues were accessed using a Wittig olefination reaction between various triphenylphosphonium salts and a key intermediate aldehyde prepared from Cryptophycin 53. Substitution on the phenyl ring of fragment A was well tolerated, and several of these analogues were equally or more potent than Cryptophycin 52 when evaluated in vitro in the CCRF-CEM leukemia cell line and in vivo against a murine pancreatic adenocarcinoma.

Chiral preparative chromatography is a technology increasingly used in the pharmaceutical industry to deliver enantiomerically pure drug candidates. A strategy for rapid screening of conditions on polysaccharide chiral stationary phases (CSPs) has been developed with an emphasis on preparative applications. Sample solubility is a major limiting factor in preparative chromatography. Most reported analytical chiral separations on polysaccharide CSPs are with eluent systems consisting of mainly hexane and small amounts of alcohol as a modifier. The intelligent chiral resolution system (ICRS) was developed to emphasize polar solvents as the first choice for eluent systems. Examples of this approach, and details on the screening procedure are presented. Using the system, chiral preparative procedures can be developed for most compounds in approximately 3 hours.

Dried blood spot (DBS) analysis using mass spectrometry is an invaluable technique for examining blood markers of inborn metabolic diseases in clinical laboratories. Implementation of DBS sampling and analysis in pharmaceutical development have more recently gained traction due to the advantages of convenience in sample procurement and logistics, as well as the innate advantages associated with the collection of lower blood volumes. While there are several realized advantages of DBS, the bioanalytical laboratory is disadvantaged and burdened with additional preparative steps prior to analysis. Therefore, improvements in the laboratory workflow for DBS analysis are necessary. Here, we describe direct blood spot analysis using desorption electrospray ionization (DESI) mass spectrometry for quantitative determination of drugs in whole blood.

Trace levels of bis(2,4-di-tert-butylphenyl)phosphate (BdtbPP) leaching from single-use bioreactors (SUBs) were recently found to be highly detrimental to mammalian cell growth. The traditional approach to detect the leachable requires time-consuming solvent extraction of SUBs. To assist the qualification of SUBs and/or their manufacturing raw materials in biopharmaceutical development and manufacturing, it is essential to develop a rapid and sensitive analytical approach for detecting this leachable and related compounds, which is described in this study.Native films from several commercially available SUBs were directly examined by desorption electrospray ionization (DESI) time-of-flight mass spectrometry (TOFMS) without sample preparation. As a comparison, the same SUBs were also analyzed by high-performance liquid chromatography (HPLC)/ultraviolet (UV) following the solvent extraction.With a suitable spray solvent selected in this study, DESI-TOFMS enabled rapid and sensitive detection of leachable compounds directly from SUBs. Accurate mass measurement from TOFMS allowed ready identification of BdtbPP, its parent analog compound, and other polymer components in the SUBs from their protonated surrogates. The relative abundances of BdtbPP in different SUBs measured by DESI-TOFMS exhibited good correlation with those from the traditional extraction-based approach with HPLC/UV.A rapid and sensitive approach was developed for direct detection of BdtbPP and other leachables from SUBs using DESI-TOFMS. The results are in high accordance with those from conventional approaches, which indicates the usefulness of the proposed method as a qualification tool for SUBs in biopharmaceutical development and also its great potential in the analysis of extractables/leachables in a wide variety of materials, process components, devices and containers used in the pharmaceutical industry.

Dried blood spot (DBS) analysis using mass spectrometry is an invaluable technique for examining blood markers of inborn metabolic diseases in clinical laboratories. Implementation of DBS sampling and analysis in pharmaceutical development have more recently gained traction due to the advantages of convenience in sample procurement and logistics, as well as the innate advantages associated with the collection of lower blood volumes. While there are several realized advantages of DBS, the bioanalytical laboratory is disadvantaged and burdened with additional preparative steps prior to analysis. Therefore, improvements in the laboratory workflow for DBS analysis are necessary. Here, we describe direct blood spot analysis using desorption electrospray ionization (DESI) mass spectrometry for quantitative determination of drugs in whole blood.

Chromatographic separations of new growth hormone secretagogue compounds were developed to support structure–activity relationship (SAR) studies in conjunction with lead optimization. These new compounds differed from Merck’s MK-677 by having two chiral centers and thus diastereomeric mixtures were generated. Separation of initial compounds in the SAR was achieved on a Kromasil C18 column using an ammonium acetate buffer and acetonitrile. However, additional candidates were not separable on C18 columns and a chiral Kromasil CHI-DMB column was used to resolve the diastereomeric compounds. The Kromasil CHI-DMB packing was also used in a preparative chromatographic system to resolve multigram quantities of secretagogue candidates for testing. Chiral separations of different intermediates were also developed in support of evolution of an asymmetric synthetic route. This report summarizes development of the preparative chromatographic system used to purify diastereomeric mixtures and chiral separations of intermediates in the synthesis.

A general synthetic approach to novel cryptophycin analogues 6 is described. N-Hydroxysuccinimide active ester 15, a key common intermediate, was converted to beta-epoxide 6 in three steps, via initial coupling with unprotected amino acid 9, followed by deprotection/macrolactamization of acyclic precursor 16, and final oxidation of styrene 7 to install the C7-C8 beta-epoxide. Cryptophycin styrenes 7 and beta-epoxides 6, bearing diverse side chains in fragment "B", were evaluated for cytotoxic activity. beta-Epoxides 6, in general, were significantly more potent than the corresponding alpha-epoxides 17 and styrenes 7. A benzyl side chain was required for potent activity, with beta-epoxide 6u, possessing a 3-Cl,4-(dimethylamino)benzyl moiety, as the most potent cytotoxic agent prepared, with an IC(50) = 54 pM, only 2-fold less than that of Cryptophycin-52 (3).

A novel, potent series of indole analogs were recently developed as MR antagonists, culminating in 14. This compound represents the first MR antagonist in this class of molecules, exhibiting picomolar binding affinity and in vivo blood pressure lowering at pharmaceutically relevant doses.

In this paper we describe the synthesis of a series of alpha-substituted analogues of the potent and selective group II metabotropic glutamate receptor (mGluR) agonist (1S,1'S,2'S)-carboxycyclopropylglycine (2, L-CCG 1). Incorporation of a substitutent on the amino acid carbon converted the agonist 2 into an antagonist. All of the compounds were prepared and tested as a series of four isomers, i.e., two racemic diastereomers. On the basis of the improvement in affinity realized for the alpha-phenylethyl analogue 3, in this paper we explored the effects of substitution on the aromatic ring as a strategy to increase the affinity to these compounds for group II mGluRs. Affinity for group II mGluRs was measured using [3H]glutamic acid (Glu) binding in rat forebrain membranes. Antagonist activity was confirmed for these compounds by measuring their ability to antagonize (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid-induced inhibition of forskolin stimulated cyclic-AMP in RGT cells transfected with human mGluR2 and mGluR3. Meta substitution on the aromatic ring of 3 with a variety of substituents, both electron donating (e.g., methyl, hydroxy, amino, methoxy, phenyl, phenoxy) and electron withdrawing (e.g., fluorine, chlorine, bromine, carboxy, trifluoromethyl) gave from 1.5- to 4.5-fold increases in affinity. Substitution with p-fluorine, as in 97 (IC50 = 0.022 +/- 0.002), was the exception. Here, a greater increase in affinity was realized than for either the ortho- or meta-substituted analogues; 97 was the most potent compound resulting from monosubstitution of the aromatic. At best, only modest increases in affinity were realized for certain compounds bearing either two chlorines or two fluorines, and two methoxy groups gave no improvement in affinity (all examined in a variety of substitution patterns). Three amino acids, 4, 5, and 104, were resolved into their four constituent isomers, and affinity and functional activity for group II mGluRs was found to reside solely in the S,S,S-isomers of each, consistent with 1. With an IC50 = 2.9 +/- 0.6 nM, the resolved xanthylmethyl compound 168 was the most potent compound from this SAR. Amino acid 168 demonstrated high plasma levels following intraperitoneal (i.p.) administration and readily penetrated into the brain. This compound, however, had only limited (approximately 5%) oral bioavailability. Systemic administration of 168 protected mice from limbic seizures produced by the mGluR agonist 3,5-dihydroxyphenylglycine, with an ED50 = 31 mg/kg (i.p., 60 min preinjection). Thus, 168 represents a valuable tool to study the role of group II mGluRs in disease.

Synthetic studies on LY228729 (3) afforded two innovative approaches for the construction of this class of partial ergoline 5HT1a receptor agonists. The first synthesis is based upon a diastereoselective epoxidation of racemic olefin 5, followed by ring opening and covalent resolution to furnish the key amino alcohol 8. Aziridination of amino alcohol 8, with subsequent tandem hydrogenolysis of the benzylic aziridine and auxiliary bonds, provided access to the optically active primary amine 13. A novel catalytic carboxamidation reaction installed the requisite side chain. Alternatively, the chiral pool was drawn upon for the single stereogenic center by virtue of l-tryptophan, albeit by a more circuitous route than expected. l-Tryptophan was differentially protected and reduced to the indoline diastereomers 26a,b which were separated by fractional crystallization. The two indoline diastereoisomers were independently cyclized by a Friedel−Crafts protocol, which under thermodynamic control afforded enantiome...

A practical, total synthesis of seco-(+)-oxaduocarmycin 3a, an analogue of the highly cytotoxic natural product, duocarmycin SA (1), is described. The 13-step synthesis features a novel and efficient intramolecular aryl radical cyclization onto a vinyl chloride as a direct entry to the (chloromethyl)indoline alkylating subunit 14. Subsequent resolution, utilizing a preparative Chiralpak AD column, provided enantiomerically pure alkylating subunits 14a and 14b which were elaborated to seco-(+) and ent-(−)-oxaduocarmycins, 3a and 3b, respectively. The natural enantiomer 3a was active at pM concentrations and exhibited 7−50-fold higher potentcy than its enantiomer 3b in in vitro cytotoxicity assays.

We have developed a high-yielding one-pot synthesis of pergolide (10) from dihydrolysergol (1), which was isolated as pergolide mesylate (6, Permax), a semisynthetic ergot alkaloid marketed for the adjunctive treatment of Parkinson's disease. The process involved the formation of quaternized amine intermediates, followed by a highly selective demethylation and thioether formation via thiomethoxide ion. A novel tandem chromatography procedure was used to remove closely related byproducts, which included an unexpected and unusual thiomethyl ether homologue of pergolide.

Pergolide is a synthetic ergot alkaloid approved for the treatment of Parkinson's disease. Process-related impurities from the synthesis are difficult to remove chemically without significant yield loss. An alternative purification procedure was necessary. Pergolide is soluble in nonaqueous solvents such as chloroform, methylene chloride, and dimethylformamide. Solubility is improved when the halocarbon is mixed with an alcohol such as methanol. These characteristics are desirable for silica gel chromatography. This paper describes the evaluation of solubility as a function of halocarbon and the development of a silica gel system to separate the process-related impurities from pergolide. The criteria for choosing a commercially available silica gel and results from purification using axial compression column technology are also discussed.

The evolution of preferred crystal-orientation fabrics is strongly sensitive to the initial fabric and texture. A perturbation in climate can induce variations in fabric and texture in the firn. Feedbacks between fabric evolution and ice deformation can enhance these variations through time and depth in an ice sheet. We model the evolution of fabric under vertical uniaxial-compression and pureshear regimes typical of ice divides. Using an analytic anisotropic flow law applied to an aggregate of distinct ice crystals, the model evolves the fabric and includes parameterizations of crystal growth, polygonization and migration recrystallization. Stress and temperature history drive the fabric evolution. Using this model, we explore the evolution of a subtle variation in near-surface fabric using both constant applied stress and a stress–temperature history based on data from Taylor Dome, East Antarctica. Our model suggests that a subtle variation in fabric caused by climate perturbations will be preserved through time and depth in an ice sheet. The stress history and polygonization rate primarily control the magnitude of the preserved climate signal. These results offer the possibility of extracting information about past climate directly from ice fabrics. Fil: Kennedy, Joseph H.. University Of Alaska; Estados Unidos Fil: Pettit, Erin C.. University Of Alaska; Estados Unidos Fil: Di Prinzio, Carlos Leonardo. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina

Polysaccharide chiral stationary phases (CSPs) Chiralcel OD, OJ, Chiralpak AD, AS, and a chemically derived Whelk-O 1 were evaluated for separation of different types of racemic compounds. When possible, small differences in a structure such as conversion of ketone to alcohol were compared to investigate differences in chiral separation capabilities of a given CSP. Comparison of separations on the Whelk-O 1 and polysaccharide CSPs are presented. Correlations between aromatic bulk of a molecule and chiral recognition as well as functional groups on molecules which enhance chiral recognition are discussed.

[1] In an ice sheet, a preferred crystal orientation fabric affects deformation rates because ice crystals are strongly anisotropic: shear along the basal plane is significantly easier than shear perpendicular to the basal plane. The effect of fabric can be as important as temperature in defining deformation rates. Fabric is typically measured using analysis of thin sections under the microscope with co-polarized light. Due to the time-consuming and destructive nature of these measurements, however, it is difficult to capture the spatial variation in fabric necessary for evincing ice sheet flow patterns. Because an ice crystal is similarly elastically anisotropic, the speed of elastic waves through ice can be used as a proxy for quantify anisotropy. We use borehole sonic logging measurements and thin section data from Dome C, East Antarctica to define the relations between apparent fabric and borehole measured elastic speeds (compressionalVP and vertically polarized shear VSV). These relations, valid for single maximum fabrics, allow in-situ, depth-continuous fabric estimates of unimodal fabric strength from borehole sonic logging. We describe the single maximum fabric usinga1: the largest eigenvalue of the second-order orientation tensor. For ice at −16°C anda1in the 0.7-1 range the relations areVP = 248 a13.7 + 3755 m s−1 and VSV = −210a17.3 + 1968 m s−1.

A practical, total synthesis of seco-(+)-oxaduocarmycin 3a, an analogue of the highly cytotoxic natural product, duocarmycin SA (1), is described. The 13-step synthesis features a novel and efficient intramolecular aryl radical cyclization onto a vinyl chloride as a direct entry to the (chloromethyl)indoline alkylating subunit 14. Subsequent resolution, utilizing a preparative Chiralpak AD column, provided enantiomerically pure alkylating subunits 14a and 14b which were elaborated to seco-(+) and ent-(−)-oxaduocarmycins, 3a and 3b, respectively. The natural enantiomer 3a was active at pM concentrations and exhibited 7−50-fold higher potentcy than its enantiomer 3b in in vitro cytotoxicity assays.

Salvia divinorum is widely cultivated in the US, Mexico, Central and South America and Europe and is consumed for its ability to produce hallucinogenic effects similar to those of other scheduled hallucinogenic drugs, such as LSD. Salvinorin A (SA), a kappa opiod receptor agonist and psychoactive constituent, is found primarily in the leaves and to a lesser extent in the stems of the plant. Herein, the analysis of intact S. divinorum leaves for SA and of acetone extracts separated using thin layer chromatography (TLC) is demonstrated using desorption electrospray ionization (DESI) mass spectrometry. The detection of SA using DESI in the positive ion mode is characterized by several ions associated with the compound – [MRH] R ,[ MRNH4] R ,[ MRNa] R ,[ 2MRNH4] R , and [2MRNa] R . Confirmation of the identity of these ions is provided through exact mass measurements using a time-of-flight (ToF) mass spectrometer. The presence of SA in the leaves was confirmed by multi-stage tandem mass spectrometry (MS n )o f the [MRH] R ion using a linear ion trap mass spectrometer. Direct analysis of the leaves revealed several species of salvinorin in addition to SA as confirmed by MS n , including salvinorin B, C, D/E, and divinatorin B. Further, the results from DESI imaging of a TLC separation of a commercial leaf extract and an acetone extract of S. divinorum leaves were in concordance with the TLC/DESI-MS results of an authentic salvinorin A standard. The present study provides an example of both the direct analysis of intact plant materials for screening illicit substances and the coupling of TLC and DESI-MS as a simple method for the examination of natural products. Copyright # 2010 John Wiley & Sons, Ltd.

A novel approach to the quantitative determination of xenobiotics in whole blood samples without sample preparation or chromatography is described. This method is based on direct analysis of microlitre volumes of blood which are spotted onto specialized paper cards and dried, with the resulting dried blood spots (DBS) analyzed directly via desorption electrospray ionization (DESI) mass spectrometry (MS). Using sitamaquine, terfenadine, and prazosin as model compounds with verapamil as a common internal standard, this methodology demonstrated detection of each compound down to 10 ng mL(-1) from DBS where standard calibration curves show linearity from 10-10,000 ng mL(-1) with r(2)0.99. Three (3) different untreated types of filter papers (Whatman 903 and 31ETF as well as Ahlstrom 237) and two (2) treated types of filter paper (Whatman FTA and FTA Elute) were examined and the effect of each surface on the recovery of each analyte was evaluated. The results show that the untreated papers provide the best substrates for DBS analysis by DESI. A more in depth study of the quantitation of sitamaquine on 31ETF paper stock provided bias and error measurements of less than 20%. The promising results shown in this study may have important implications in the areas of therapeutic drug monitoring (TDM), clinical and forensic toxicology, and pharmacology.

Methodology for determination of the enantiomeric purity of sixteen 2,3-epoxy-1-propanols (glycidols) is delineated. Conversion of these epoxy alcohols and 1-naphthyl isocyanate (NIC) into the 1-naphthyl carbamates is catalyzed by dibutyltin diacetate. Enantiomers of these carbamates are resolved on a Chiralcel® OD column. Advantages of this method include mildness of reaction conditions, nonreliance on diastereomeric derivatization, and appendage of a UV-absorbing chromophore to the analyte.

Cryptophycin 52 (LY355703) is a potent antiproliferative analogue of the marine natural product cryptophycin 1. It has been shown to have a broad range of antitumor activity against human tumor xenografts and murine tumors including tumors resistant to Taxol and Adriamycin. Its mechanism of action involves arresting cells in the G2-M phase of the cell cycle by binding to microtubules and suppressing their dynamics. This 16-membered depsipeptide can be divided into four major subunits or fragments (A-D). We reported previously on our synthetic efforts around fragment A and discovered that this region of the molecule was amenable to a structure-activity relationship study that resulted in highly active antiproliferative agents when evaluated in the CEM leukemia cell line. The synthetic analogues were designed to help improve the efficacy and aqueous solubility of the parent compound; therefore, many in this series contained ionizable functional groups such as an amino group, a hydroxy group, or a carboxylic acid. Although several of these analogues showed improvements in potency over cryptophycin 52 in drug-sensitive tumor xenograft models, many lost their activity against Adriamycin-resistant tumor lines. It was discovered on additional in vitro evaluation that these analogues became good substrates of the multidrug resistance transporter P-glycoprotein.

Lactams are key components of many peptidomimetic structures. Five- and six-membered lactam peptidomimetics with hydrogen or amino acid side chains at the alpha-position can be constructed from peptide precursors during a solid-phase synthesis. There is no significant racemization of remote stereocenters during synthesis.