bluuebunny/crossref_metadata_2025 huggingface dataset:
A tandem reflectron time‐of‐flight mass spectrometer for the investigation of laser photofragmentation of molecular ions
Authors: Jia W. J. , Ledingham K. W. D. , Scott C. T. J. , Kosmidis C. , Singhal R. P.
Published: May 2005

A tandem reflectron time‐of‐flight mass spectrometer has been constructed for the investigation of laser photofragmentation of selected molecular ions. Ions are generated by an ablation laser and attracted by ion optics into the field‐free flight region of a reflectron time‐of‐flight mass spectrometer. Laser photofragmentation of selected molecular ions takes place at the turn‐around point of ions in the reflectron. Fragmentation mass calibration, parent ion selection, ion collection effects, reflectron field effects and the mass resolution of this tandem reflectron time‐of‐flight mass spectrometer are described. Furthermore it is shown that laser parameters may be used to control the fragmentation pattern.
Pyrolysis/gas chromatography/mass spectrometry of lignocellulose
Authors: Galletti Guido C. , Bocchini Paola
Published: May 2005

The use of pyrolysis/gas chromatography/mass spectrometry (PY/GC/MS) to determine the molecular composition of lignocellulose is reviewed and the technique illustrated with applications on some novel systems. Constituents and structural arrangement of lignocellulosic polymers in plant cell wall are briefly described. The basic principles of pyrolysis and the main advantages and disadvantages of PY/GC/MS are discussed. PY/GC/MS analyses of (a) paper industry effluents, (b) agricultural by‐products subjected to biological processes of delignification and (c) recycled paper are presented as examples of the amount of information that PY/GC/MS can provide on lignin classification and monitoring of delignification treatments as well as on the fingerprinting of lignocellulosic materials. The ion trap detector mass spectra of 56 pyrolysis products of lignocellulose, including compounds of phenolic, furanic and pyranic nature, are shown.
Enhancement of methylation analysis of complex carbohydrates using pyridine as reagent in chemical ionization mass spectrometry
Authors: Pätoprstý V. , Kováčik V. , Karácsonyi S.
Published: May 2005

Under the conditions of chemical ionization (CI) mass spectrometry, protonated pyridine [PyrH]+ and partially methylated alditol acetates (PMAAs) form very stable adducts. The CI mass spectra exhibit, exclusively, peaks due to quasimolecular [M + PyrH]+ adduct ions. The methylation analysis of complex carbohydrates can be enhanced by using the pyridine CI mass spectra to complement electron impact mass spectra and gas chromatography data. As a result, the sensitivity as well as the accuracy of quantitative analysis of PMMA components is increased.
Modified ionspray interface for supercritical fluid chromatography/mass spectrometry: Interface design and initial results
Authors: Pinkston J. David , Baker Timothy R.
Published: May 2005

A pneumatically assisted electrospray liquid chromatography/mass spectrometry interface has been modified for use with open‐tubular supercritical fluid chromatography (SFC). The modified interface houses the SFC flow restrictor within the spray device. A sheath‐flow liquid of methanol or methanol/water containing ammonium acetate flows coaxially to the restrictor. The addition of the sheath‐flow liquid results in the ionization of analytes known to be in a neutral charge state during the chromatographic separation. The sheath‐flow liquid also allows for the independent operation of the chromatograph and the mass spectrometer. Both could be operated under optimum conditions. The operation of the interface was optimized using a solution of poly(dimethylsiloxane) in CO2 introduced by continuous infusion. We also report the application of the modified instrument to samples containing amines and propoxylated alcohols.
Quantification of polyphosphoinositides using selected ion monitoring electrospray mass spectrometry
Authors: Michelsen Peter , Jergil Bengt , Odham Göran
Published: May 2005

Polyphosphoinositides (PIP) and (PIP2) show prominent negative singly and doubly charged deprotonated molecules in electrospray mass spectrometry. These ions can be used for quantification of PIP and PIP2 in the low picomole range, without prior chromatographic separation, using selected ion monitoring and consecutive measurements of the signals from the deprotonated singly charged molecules. The dose response curves for both compounds are linear. In a complex matrix consisting of polar lipids (Folch extract) PIP and PIP2 monitored at m/z 965.4 and 1045.5 (stearoyl and arachidonoyl) were determined in the low picomole range, at a flow rate of 100 μL/min. Collision‐induced decomposition of PIP and PIP2 using a mixture of xenon and argon at 25 eV afforded identical high mass ions formed by loss of a molecule of water from PIP and a phosphate group and a molecule of water from PIP2. The results indicate that polyphosphoinositides, and biologically relevant changes in their concentrations, can be quantified directly in cells and cellular membranes by selected‐ion monitoring with electrospray mass spectrometry.
Application of the fast‐evaporation sample preparation method for improving quantification of angiotensin II by matrix‐assisted laser desorption/ionization
Authors: Nicola Anthony J. , Gusev Arkady I. , Proctor Andrew , Jackson Edwin K. , Hercules David M.
Published: May 2005

The fast‐evaporation method of sample preparation has been applied for quantitative analysis using matrix‐assisted laser desorption/ionization (MALDI) mass spectrometry. An instrumental protocol focusing on improvement of shot‐to‐shot repeatability and compensation for signal degradation has been developed for quantification of angiotensin II using the fast‐evaporation technique and an internal standard. The fast‐evaporation method was compared to the standard method of sample preparation (using a multicomponent matrix) in the quantitative analysis of angiotensin II, and found to be superior in several respects. Improvement in sample homogeneity using the fast‐evaporation method enhanced both point‐to‐point repeatibility and sample‐to‐sample reproducibility. The relative standard deviations of the analyte/internal standard ratios (point RSD) were decreased by a factor of three compared to those obtained using the multicomponent matrix method. The average point RSD was found to be ca. 5% for the fast‐evaporation technique. Two internal standards were evaluated for quantification of angiotensin II. The better one, 1‐SAR‐8‐Ile angiotensin II, yielded a relative standard deviation of the standard curve slope of ca. 2.2% over two orders of magnitude of concentration (45 nM to 3000 nM), an improvement by a factor of two over the standard preparation method. Renal microdialysate samples, spiked with angiotensin II and the internal standard 1‐SAR‐8‐Ile angiotensin II, were also analyzed using the fast‐evaporation technique. The detection limit was calculated to be in the high attomole range (675amol). Furthermore, the accuracy for a single determination of angiotensin II concentration in these samples was found to be 13.9% with a relative error of 8.19%.
The role of ion–neutral reorientation in the unimolecular reactivity of e‐ionized amines. The influence of the size of the fragments
Authors: Longevialle Pierre
Published: May 2005

During the unimolecular decomposition of an ion IN→I(ion) + N(neutral), the fragments may mutually reorient before decomposition, when the energy has reached the reorientation critical energy. After I‐N reorientation, I and N have only a very low probability of recombining into the original IN structure, but can only decompose (or occasionally follow a different reaction pathway, if thermochemically allowed). As a consequence, decompositions of metastable ions are irreversibly decided as soon as their corresponding I‐N reorientation threshold has been reached. It is shown, from the mass‐analysed ion kinetic energy of several series of homologous primary amines, that the competition between α‐cleavages (and the occasionally accompanying losses of alkanes) is governed by the relative I‐N reorientation–(rather than decomposition)–critical energies.

When the neutral has no permanent dipole, the I‐N reorientation critical energy depends on the sizes of the fragments, especially that of the fragment ion. An interpretation is proposed related to the McAdoo and Hudson hypothesis.27
High temperature mass spectrometric study of the B2O3Al2O3 system at 1248–1850 K
Authors: Stolyarova V. L. , Shilov A. L. , Ivanov G. G. , Shultz M. M. , Seetharaman S.
Published: May 2005

The high‐temperature mass spectrometric Knudsen effusion method has been used to study the vaporization processes and thermodynamic properties of the B2O3Al2O3 system in the temperature range 1248–1850 K. Data on the B2O3 partial vapour pressures and the B2O3 activities in the system under consideration were obtained. The enthalpies of formation of Al4B2O9 and Al18B4O33 have been evaluated from the values of the enthalpies of B2O3 sublimation from boron oxide and from these compounds. Comparison is made between the available phase diagram of the B2O3Al2O3 system and the results obtained in the present study, using the complete isothermal vaporization method.
Pyrolysis gas chromatography/mass spectrometry used to simultaneously determine essential oil and phenolic compounds in the monks' pepper vitex agnus‐castus L
Authors: Galletti Guido C. , Russo Maria Teresa , Bocchini Paola
Published: May 2005

Pyrolysis/gas chromatography/mass spectrometry (PY/GC/MS) was used as a microtechnique for the simultaneous analysis of various classes of compounds in leaves and berries of Vitex agnus‐castus L. (Verbenaceae) plants growing wild in Calabria. Terpene and sesquiterpene hydrocarbons from the essential‐oil fraction, simple phenolics, tentatively ascribed to moieties of flavonoids and glucosides, and free and esterified fatty acids were determined. Aliquots in the milligram range of plant material were assayed as such with no extraction or use of different analytical techniques for the different chemical classes under investigation. White the terpene and sesquiterpene yields remained practically constant over the entire range of pyrolysis temperatures examined, i.e. 200–900 °C, phenolics appeared at a pyrolysis temperature of 300 °C and reached a maximum at 700–900 °C. Pyrolysis in the presence of tetramethylammonium hydroxide was carried out in order to perform the so‐called thermally assisted hydrolysis methylation/gas chromatography/mass spectrometry (THM/GC/MS) and analyse more polar compounds, such as fatty acids, as their methylated derivatives.
Determination of artefact peaks in mass‐analysed ion kinetic energy spectra using a new linked scan for ebe geometry magnetic sector instruments
Authors: Mouget Yves , Bertrand Michel J.
Published: May 2005

The possible presence of artefact peaks in mass‐analyzed ion kinetic energy (MIKE) spectra has been recognized when such scans are performed using a two‐sector instrument of reverse (BE) configuration. Since the presence of an artefact peak can be misleading when interpreting a spectrum, a new scan is proposed which allows these artefacts to be identified. This scan involves linking and scanning the two electrostatic sectors of an E1BE2 geometry instrument, while maintaining the magnet at the mass selected for the MIKE scan. This selected mass‐analyzed ion kinetic energy (SMIKE) scan at E1=E2 results in a spectrum containing only artefact peaks that can be present in the corresponding MIKE spectrum.
Revisit of MALDI for small proteins
Authors: Zhu Y. F. , Lee K. L. , Tang K. , Allman S. L. , Taranenko N. I. , Chen C. H.
Published: May 2005

Matrix‐assisted laser desorption/ionization (MALDI) was used for several small proteins (such as insulin) and for peptides. It was found that the detection efficiencies of MALDI for the insulin B chain and the insulin A chain are drastically different. Similar phenomena were also observed for various types of peptides. The positive‐ion signal of MALDI in detecting proteins or peptides was found to be greatly enhanced by the presence of a basic amino acid in their chains. The experimental results indicate that this enhancement may arise from proton transfer in solution by an acid‐base reaction between the protein/peptide and matrix molecule. This pre‐protonated mechanism provides a low energy barrier for the ionization of peptides in a MALDI process, and greatly reduces the energy threshold of MALDI. Matrix effects on the ionization mechanism are discussed.
Liquid secondary‐ion mass spectrometry of peptides containing multiple tyrosine‐O‐sulfates
Authors: Yagami Takeshi , Kitagawa Kouki , Futaki Shiroh
Published: May 2005

The behavior of peptides containing multiple tyrosine‐O‐sulfates in liquid secondary‐ion mass spectrometry (LSIMS) has been investigated. In the positive‐ion spectra of the peptides containing two tyrosine‐O‐sulfates, Cionin and CCK‐associated C‐terminal nonapeptide (CAP‐9), the completely desulfated [M+H−2SO3]+ ions formed the base peaks, accompanying the significantly less‐intense [M+H]+ and [M+H−SO3]+ ions. In the negative‐ion spectra of these peptides, the [M−H]− and [M−H−SO3]− ions gave prominent peaks with significantly weaker [M−H−2SO3]− ions. In the case of a peptide containing three tyrosine‐O‐sulfates, [Tyr(SO3H)1]CAP‐9, the completely desulfated [M+H−3SO3]+ ion again formed the base peak in the positive‐ion spectrum. On the other hand, the sulfated tyrosine‐containing [M+H]+, [M+H−SO3]+, and [M+H−2SO3]+ ions were of negligible abundance compared to the spectra of peptides containing two tyrosine‐O‐sulfates. We observed an intriguing ‘ladder fragmentation pattern’ in the negative‐ion spectrum of this triply‐sulfated peptide. The ladder consisted of the [M−H]−, [M−H−SO3]−, and [M−H−2SO3]− ions, but without the completely desulfated [M−H−3SO3]− ion. These characteristic fragmentation patterns of sulfated tyrosine‐containing peptides were considered to bear a close correlation with the inherent acid‐lability of a tyrosine‐O‐sulfate in solution. A possible mechanism has been proposed to explain the fragmentation patterns in the gaseous phase, in which a proton plays a decisive role.
Collisionally‐activated dissociation spectra of linear peptides in matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry
Authors: Kosaka T. , Ishikawa T. , Kinoshita T.
Published: May 2005

Collisionally‐activated dissociation (CAD) studies of linear peptides were performed using matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. Four different gases, viz. helium, nitrogen, argon and xenon, were introduced into a gas cell, installed close to the ion source of TOF mass spectrometer, to obtain high‐energy CAD information. The CAD spectral patterns for the linear peptides obtained using the four gases were almost the same as each other. The fragments characteristically obtained in conventional high‐energy CAD using tandem mass spectrometry were observed also in these spectra. A difference between CAD spectra and post‐source decay product‐ion spectra has been demonstrated.
Determination of the pesticides diflubenzuron and clofentezine in plums, strawberries and blackcurrant‐based fruit drinks by high performance liquid chromatographic/atmospheric pressure chemical ionization‐mass spectrometry
Authors: Barnes Karen A. , Fussell Richard J. , Startin James R. , Thorpe Stephen A. , Reynolds Stewart L.
Published: May 2005

A high performance liquid chromatographic/atmospheric pressure chemical ionization‐mass spectrometric (HPLC/APCI‐MS) method has been developed for the determination of the pesticides diflubenzuron (1‐(4‐chlorophenyl)‐3‐(2,6‐difluorobenzoyl)urea) and clofentezine (3,6‐bis(2‐chlorophenyl)‐1,2,4,5‐tetrazine) in plums, strawberries and blackcurrant‐based fruit drinks. Samples were homogenized with acetone, extracted into dichloromethane + cyclohexane and cleaned‐up by high performance gel permeation chromatography. HPLC was performed on an ODS column with methanol + water at 1 mL/min. Detection was by negative‐ion selected‐ion monitoring APCI‐MS. Comparison of response with solvent and matrix‐matched standards showed some ehancement of response for the latter, and these standards were consequently used for quantification. The calibration was linear over the range 0.05–0.50 ng/μL in all three matrices. The mean overall recovery of diflubenzuron and clofentezine from spiked extracts (0.086 mg/kg) in all three matrices was 76% and 70% respectively with relative standard deviations of 15% and 12% respectively (n = 12). The limit of detection was both compound and commodity dependent and ranged from 0.01–0.05 ng/μL, equivalent to 0.003–0.014 mg/kg in the crop.
Identification of urinary and biliary conjugated metabolites of the neuromuscular blocker 51w89 by liquid chromatography/mass spectrometry
Authors: Dear Gordon J. , Jones Anne E. , Pleasance Stephen , Harrelson Jane C. , Johnson Thomas E.
Published: May 2005

Cisatracurium, (1R, 1′R, 2R, 2′R)‐2,2‐[1,5‐pentanediylbis‐[oxy(3‐oxo‐3,1‐propanediyl)]]bis[1‐[(3,4‐dimethoxy‐phenyl)‐methyl]‐1,2,3,4‐tetrahydro‐6,7‐dimethoxy‐2‐methylisoquinolinium] dibenzenesulphonate (51W89), is an intermediate‐acting neuromuscular blocking agent. 51W89 is one of ten isomers contained in Tracrium® (atracurium besylate) and represents' approximately 15 percent of the atracurium mixture. Clinical studies have indicated that 51W89 is more potent and is significantly weaker as a histamine releaser than atracurium. In vitro studies in human plasma have shown that, like atracurium, 51W89 spontaneously degrades at physiological pH by Hoffmann elimination to form laudanosine and the quaternary monoacrylate. Subsequent ester hydrolysis of the monoacrylate generates the monoquaternary alcohol. In rat plasma, 51W89 is also metabolized by non‐specific carboxylesterases to the monoquaternary alcohol and the monoquaternary acid, the former being rapidly hydrolysed further to the more stable acid. It has been reported that laudanosine can be further metabolized via N‐demethylation to yield tetrahydropapaverine. The rate‐limiting step in the degradation of 51W89 in human plasma is Hofmann elimination, whilst in rat plasma, the action of non‐specific carboxylesterases is rate limiting. As part of the development of 51W89, the disposition of 14C‐51W89 following a single intravenous bolus dose was studied in various animal species and humans. In the present work, we describe the identification of 51W89 metabolites in urine and bite from these studies by high performance liquid chromatography/mass spectrometry using pneumatically‐assisted electrospray ionization coupled to an on‐line radioactivity monitor. This methodology enabled rapid and sensitive screening of biological samples with minimal sample preparation. Structural confirmation of metabolites was obtained by tandem mass spectrometry. In addition to the expected metabolites, a number of urinary and biliary O‐glucuronic acid conjugate of monodesmethyl laudanosine and monodesmethyl tetrahdropapaverine were identified, which cochromatographed with an early eluting ‘unknown’ in the radioprofile. A sulphate conjugate of monodesmethyl laudanosine was also identified in cat bile. The characterization of these metabolites was assisted by the incorporation of on‐line radioactivity monitoring during mass spectroscopic analysis, which provided an invaluable means to distinguish drug‐related and endogenous material.
Charge‐remote fragmentation of ecdysteroids conjugated with phosphoric acid
Authors: Ikeda Midori , Fujita Tsuyoshi , Naoki Hideo , Naya Yoko , Mamiya Yoshitaka , Kamba Mari , Sonobe Haruyuki
Published: May 2005

Successful application of tandem mass spectrometry on a series of the ecdysteroid phosphates (eddysteroids conjugated with phosphoric acid) led to general information for their characterization. The 22‐phosphates and the 2‐(or 3‐)phosphates can be definitely distinguished by their charge‐remote fragmentation patterns. In the case of the 22‐phosphates, information about the side‐chain moiety is readily obtained. In the case of the 2‐(or 3‐)phosphates, information about the ring as well as the side‐chain is readily available. Neither the positional isomers (2‐ and 3‐phosphates) in the A‐ring nor the configurational isomers (α and β) can be distinguished.
Molecular mass measurement of polymerase chain reaction products amplified from human blood dna by electrospray ionization mass spectrometry
Authors: Naito Yasuhiro , Ishikawa Keiichiro , Koga Yoshinori , Tsuneyoshi Toshihiro , Terunuma Hideya , Arakawa Ryuichi
Published: May 2005

We report here on the first analysis of polymerase chain reaction (PCR) products amplified from a small amount of human blood DNA by electrospray ionization mass spectrometry (ESI‐MS). Adenomatous polyposis coli (APC) gene fragment of about 50 base pairs (bp) with a relative molecular mass (Mr) of approximately 15 000 u was amplified from human blood DNA by PCR. The accurate molecular mass of the PCR products was determined with an accuracy of ∼0.005% by ESI‐MS. The amount of DNA used was only 100 ng (∼ 50 zmol; the theoretically required amount of blood is therefore less than 1 μL for PCR). The ESI‐MS measurement of the PCR products proved to be a new accurate, sensitive and fast tool for gene diagnosis.
Capillary zone electrophoresis/electrospray ionization mass spectrométry for the characterization of drugs of forensic interest
Authors: Curcuruto Ornella , Zaramella Alessio , Hamdan Mahmoud , Turrina Stefania , Tagliaro Franco
Published: May 2005

Solutions containing between six and thirteen drug substances of forensic interest have been examined by capillary zone electrophoresis/electrospray mass spectrometry (CZE/ES‐MS). The effects of citrate buffer concentration and its content of organic modifiers on the migration time, resolution and migration order of the various components were assessed. Performing CZE/ES‐MS in full‐scan mode at elevated cone (skimmer) voltage allowed differentiation between nalorphine and thebaine which have isomeric structures.
Effects of solvent composition on molecular ion response in electrospray mass spectrometry: Investigation of the ionization processes
Authors: Zhou Shaolian , Hamburger Matthias
Published: May 2005

Electrospray ionization of four structurally diverse natural products, actinomycin D, digitoxin, reserpine and quercetin was investigated. Specific attention was paid to the molecular ions formed under typical reversed‐phase high‐performance liquid chromatography (RP‐HPLC) conditions. The response characteristics of [M + H]+, [M + NH4]+ and [M + Na]+ Ions, observed upon addition of formic acid, ammonium formate and sodium acetate were studied. It was found that the highest response for these molecular ions was obtained with proton, ammonium and sodium ion concentrations of approximately 10−3 ∼ 10−4 M. This critical concentration appears to be correlated with the equilibrium between the thermodynamically controlled molecular ions in solution and electrospray produced gas‐phase ions. Gas‐phase ion reactions in the ion transfer region were investigated for digitoxin, and the mechanism of gas‐phase ion formation is briefly discussed.
Direct database searching with MALDI‐PSD spectra of peptides
Authors: Griffin Patrick R. , Maccoss Michael J. , Blevins Richard A. , Aaronson Jeffrey S. , Eng Jimmy K. , Yates Iii John R. ,
Published: May 2005

The analysis of matrix‐assisted laser desorption ionization post‐source decay (MALDI‐PSD) mass spectra of peptides by using the cross‐correlation method for database searching is illustrated. MALDI‐PSD mass spectra are shown to contain sufficient fragmentation information to uniquely identify the correct amino acid sequence from large protein databases (∼160000 entries). A search employing the MALDI‐PSD mass spectrum of a phosphorylated peptide that correctly identifies the amino acid sequence and the site of phosphorylation is also illustrated.
Comparison of fragmentation modes for the structural determination of complex oligosaccharides ionized by matrix‐assisted laser desorption/ionization mass spectrometry
Authors: Harvey David J. , Naven T. J. P. , Küster B. , Bateman Robert H. , Green Martin R. , Critchley Glen
Published: May 2005

Fragment ions from underivatized N‐linked oligosaccharides ionized by matrix‐assisted laser desorption/ionization mass spectrometry were obtained by spontaneous fragmentation on a magnetic sector mass spectrometer, by post‐source decay (PSD) on a reflectron time‐of‐flight (TOF) instrument and by collision‐induced dissociation on a magnetic sector instrument fitted with an orthogonal‐TOF analyser. Spontaneous fragmentation on the magnetic sector instrument produced ions mainly by glycosidic cleavage together with two abundant ions formed by cross‐ring cleavage of the reducing‐terminal residue. The PSD spectra were similar, the majority of ions being formed by glycosidic cleavage. Internal fragment ions were abundant. High‐energy collision‐induced dissociation spectra, recorded with the orthogonal‐TOF analyser, differed considerably from the other types of spectra, particularly in the appearance of major fragment ions produced by cross‐ring cleavages of most of the constituent monosaccharide residues. These ions allowed much sequence and branching information to be obtained from the oligosaccharide.
Cooling time and pressure effects on competitive thermalization/activation processes by resonance excitation on ITMS
Authors: Liere P. , Bouchonnet S. , March R. E. , Tabet J. C.
Published: May 2005

The classical n‐butylbenzene model is used to estimate the qualitative variation of the precursor ion internal energy by the resonant excitation method in an ion‐trap mass spectrometer. The kinetic energy thermalization process is confirmed by insertion of a cooling time (⩽10ms under our conditions). An initial internal energy relaxation process due to collisions between the molecular ion and neutral species of n‐butylbenzene is proposed. The larger amount of internal energy deposited in ions as the helium pressure is increased can be explained in terms of the number of collisions between the molecular ion and helium atoms, the competition between ion dissociation and ion ejection, the rate constant of dissociation and the secular axial frequency resolution of the isolated ions. Increased analyte pressure does not accelerate the ion relaxation process, probably due to the space charge effects. In summary, variation of helium pressure and cooling time permit optimization of ion internal energy deposition leading to enhanced sensitivity in MS/MS experiments.
Functional properties of models for direction selectivity in the retina
Authors: Grzywacz Norberto M. , Koch Christof
Published: May 2005

Poggio and Reichardt (Kybernetik, 13:223–227, 1973) showed that if the average response of a visual system to a moving stimulus is directionally selective, then this sensitivity must be mediated by a nonlinear operation. In particular, it has been proposed that at the behavioral level, motion‐sensitive biological systems are implemented by quadratic nonlinearities (Hassenstein and Reichardt: Z. Naturforsch., 11b:513–524, 1956; van Santen and Sperling: J. Opt. Soc. Am. [A] 1:451–473, 1984; Adelson and Bergen: J. Opt. Soc. Am. [A], 2:284–299, 1985). This paper analyzes theoretically two nonlinear neural mechanisms that possibly underlie retinal direction selectivity and explores the conditions under which they behave as a quadratic nonlinearity. The first mechanism is shunting inhibition (Torre and Poggio: Proc. R. Soc. Lond. [Biol.], 202:409–416, 1978), and the second consists of the linear combination of the outputs of a depolarizing and a hyperpolarizing synapse, followed by a threshold operation. It was found that although sometimes possible, it is in practice hard to approximate the Shunting Inhibition and the Threshold models for direction selectivity by quadratic systems. For instance, the level of the threshold on the Threshold model must be close to the steady‐state level of the cell's combined synaptic input. Furthermore, for both the Shunting and the Threshold models, the approximation by a quadratic system is only possible for a small range of low contrast stimuli and for situations where the rectifications due to the ON–OFF mechanisms, and to the ganglion cells' action potentials, can be linearized. The main question that this paper leaves open is, how do we account for the apparent quadratic properties of motion perception given that the same properties seem so fragile at the single cell level? Finally, as a result of this study, some system analysis experiments were proposed that can distinguish between different instances of the models.
Co‐localization of N‐acetyl‐aspartyl‐glutamate in central cholinergic, noradrenergic, and serotonergic neurons
Authors: Forloni Gianluigi , Grzanna Reinhard , Blakely Randy D. , Coyle Joseph T.
Published: May 2005

An immunohistochemical technique for simultaneously visualizing two different antigens has been used to investigate the presence of the acidic dipeptide, N‐acetyl‐aspartyl‐glutamate (NAAG), in cholinergic, noradrenergic‐adrenergic, and serotonergic neurons within CNS. The brain slices were processed sequentially with purified antisera against NAAG and then monoclonal antibody against choline acetyltransferase (ChAT), a marker for cholinergic neurons, or antiserum against dopamine‐β‐hydroxylase (DBH), a marker of noradrenergic‐adrenergic neurons, or antiserum against serotonin (5HT). Both antigens were revealed by the peroxidase reaction but with different chromogens, which are easily distinguishable.

An intense double staining of NAAG‐like immunoreactivity (NAAG‐LI) and ChAT was observed in the motoneurons of the spinal cord as well as in the several motor components of cranial nerve nuclei including facial, ambiguus, and trigeminal nuclei. A partial colocalization of NAAG‐LI and ChAT was evident in the perikarya of the basal forebrain cholinergic system, whereas cholinergic neurons of the medial septum exhibited only sporadic staining for NAAG‐LI. A complete coexistence of NAAG‐LI and DBH was observed in the locus coeruleus. Most of the other noradrenergic and adrenergic cell groups of the medulla region exhibited substantial co‐localization with the exception of the A2 cell group, which was virtually devoid of NAAG‐LI.

In the dorsal raphe, only a low percentage of serotonergic neurons stained for NAAG‐LI. The co‐existence of NAAG‐LI and serotonin was more evident in the neurons of the median raphe, although the majority of cells failed to show double staining. In the raphe pallidus and raphe magnus, the co‐existence with NAAG‐LI remained partial but involved a large percentage of serotonergic neurons. These results suggest a more widespread neuronal function of NAAG in addition to its proposed role as putative neurotransmitter in a subgroup of glutamatergic neurons.
Modification of 5‐HT neuron properties by sustained administration of the 5‐HT1A agonist gepirone: Electrophysiological studies in the rat brain
Authors: Blier Pierre , De Montigny Claude
Published: May 2005

The sustained administration of the 5‐HT1A agonist gepirone (15 mg/kg/day, s.c.) in the rat produced an initial decrease of the firing activity of dorsal raphe 5‐HT neurons which was followed by a progressive recovery to normal after 14 days of treatment. At this point in time, the effect of intravenous lysergic acid diethylamide (LSD) on the firing activity of 5‐HT neurons was markedly reduced, whereas those of 8‐hydroxy‐2‐N, N‐propylamino‐tetralin (8‐OH‐DPAT) and of gepirone were unchanged; however, the responsiveness of 5‐HT neurons to direct microintophoretic application of 5‐HT, LSD, 8‐OH‐DPAT, and gepirone, but not of GABA, was reduced. The responsiveness of postsynaptic dorsal hippocampus pyramidal neurons to 5‐HT, 8‐OH‐DPAT, and gepirone was not altered by the 14‐day gepirone treatment. The effectiveness of the electrical stimulation of the ascending 5‐HT pathway in reducing pyramidal neuron firing activity was not significantly modified in rats treated with gepirone for 14 days. Furthermore, this treatment did not alter the function of the terminal 5‐HT autoreceptor. It is concluded that the progressive restoration of the firing activity of 5‐HT neurons, due to a desensitization of the somatodendritic 5‐HT autoreceptor, combined with the direct activation of normosensitive postsynaptic 5‐HT1A receptor by gepirone, should result in an augmented tonic activation of postsynaptic 5‐HT1A receptors. The progressive appearance of this phenomenon would be consistent with the time course of the clinical anxiolytic, and possibly antidepressant, effects of gepirone.
PCP‐induced alterations in cerebral glucose utilization in rat brain: Blockade by metaphit, a PCP‐receptor‐acylating agent
Authors: Tamminga C. A. , Tanimoto K. , Kuo S. , Chase T. N. , Contreras P. C. , Rice K. C. , Jackson A. E. , O'Donohue T. L.
Published: May 2005

The effects of phencyclidine (PCP) on regional cerebral glucose utilization was determined by using quantitative autoradiography with [14C]‐2‐deoxyglucose. PCP increased brain metabolism in selected areas of cortex, particularly limbic, and in the basal ganglia and thalamus, whereas the drug decreased metabolism in areas related to audition. These results are consistent with the known physiology of central PCP neurons and may help to suggest brain areas involved in PCP‐mediated actions. Moreover, based on the behavioral similarities between PCP psychosis and an acute schizophrenic episode, these data may be relevant to the understanding of schizophrenia. The PCP‐receptoracylating agent, metaphit, blocked most of these PCP actions. In addition, metaphit by itself was found to diminish glucose utilization rather uniformly throughout brain. These results indicate an antagonist effect of metaphit on the PCP system and suggest a widespread action of metaphit, putatively at a PCP‐related site, possibly in connection with the N‐methyl‐D‐aspartate (NMDA) receptor.
Stolen Cloaks in Aristophanes' Ecclesiazusae
Authors: Compton-Engle Gwendolyn
Published: May 2005

I argue that the cloaks that the women steal from their husbands in Aristophanes' Ecclesiazusae have thematic resonances that extend well beyond their use as part of the women's transvestite disguise. The filching of the cloaks is portrayed as lvpodusia ("mugging") by Blepyrus at lines 535–38. Once he makes this association, the cloaks come to signify not only gender reversal but also the oikos-polis dialectic and socioeconomic issues that are at the play's core. Praxagora capitalizes on these associations as she presents her agenda to Blepyrus. The stolen cloaks thus link the cross-dressing and economic aspects of the play.
Inside Out: In Defense of Form
Authors: Lowrie Michele
Published: May 2005

Three case studies show a consistent preoccupation with a similar formal problem within different areas of inquiry. The problem is the relation of inside to outside. The areas are genre criticism, speech act theory, and sovereignty theory. Genre, an external feature of a text, is a topic discussed within Latin poetry. Poets can assert their poetry's power in the world only through poetry. The sovereign, who is subject to the law, also lies outside it in his ability to suspend it. In each case, the power to determine reality and the power to represent it are in competition. The personal voice in this paper responds to Lowell Edmunds' questions about methodology.
Trying Not To Cheat: Responses to Inconsistencies in Roman Epic
Authors: O'Hara James J.
Published: May 2005

This paper discusses some of the arguments and methods of a forthcoming study of inconsistencies in Roman epic. After description of the shape of that book, the paper moves through some passages and problems in Catullus 64, Lucretius' De rerum natura, Vergil's Aeneid, Ovid's Metamorphoses, and Lucan's Pharsalia. My central claim is that not all inconsistencies need to be explained or amended away, or faulted, and that some need to be interpreted. Some types of "cheating," or of avoiding reading and interpreting the words in the text in the order in which they appear, are discussed.
A Spanish Converso's Quest for Justice: The Life and Dream Fiction of Antonio Enriquez Gomez
Authors: Warshawsky Matthew
Published: May 2005

Antonio Enr�quez G�mez was a seventeenth-century Spanish converso (convert), or New Christian, author whose peripatetic life and multiple identities well represent the perilous and sad reality of Spaniards of Jewish descent compelled to live as Christians. This article will present historical background of the converso experience in Spain as a means of contextualizing the subsequent description of Enr�quez G�mez's life during the 1600s both in and out of Spain. Analysis of three narratives written in the form of dreams while the author was living as an exile in France will argue that his criticism of invented inquisitions and those individuals who work for them is not an apology for Judaism. Rather, the author's resistance to fictionalized inquisitions is a call to reform certain practices of the Spanish Inquisition, so that Old Christians (those without Jewish or Muslim lineage) and converts alike can live in a society less judgmental of ancestry and more apt to judge people based on the virtue of their actions.
Sorption of trivalent plutonium onto UO2and the effect of the solid phase on the Pu oxidation state
Authors: Olsson Mattias , Glänneskog Henrik , Jakobsson Anna-Maria , Nilsson Hans , Albinsson Yngve
Published: May 2005

A problem with plutonium in sorption studies is its tendency to occur in a mix of oxidation states. This work was a study of the sorption of plutonium on the solid phase UO2— in a perchlorate medium as a function of pH — where plutonium is kept in its trivalent oxidation state. Experiments also showed that uranium(IV) oxide can reduce Pu(IV) to Pu(III) in an acidic solution and maintain it in that state. It was observed at the same time that the chemically inert solid phases TiO2and ThO2possibly increase the rate of disproportionation of Pu(IV) at a pH of about 0.5. In accordance with previous studies MnO2was found to have an oxidizing effect, converting Pu(IV) into Pu(VI).

A comparison is made between the sorption of Th(IV), Pu(III) and Co(II) on UO2and TiO2, and Pu(VI) on TiO2.
Recovery of minor actinides from HLLW using the DIAMEX process
Authors: Serrano-Purroy Daniel , Baron P. , Christiansen Birgit , Malmbeck R. , Sorel C. , Glatz J.-P.
Published: May 2005

In this work a hot demonstration of the DIAMEX process using the new reference molecule DMDOHEMA (N,N′-DiMethyl-N,N′-DiOctylHexylEthoxyMalonAmide) and genuine high-level PUREX raffinate as feed is reported. The continuous counter-current experiment was carried out in a 16-stage centrifugal extractor battery, installed in a hot cell. In order to produce a representative High Level Liquid Waste (HLLW) a PUREX process was applied on dissolved fuel using the same equipment. It was demonstrated that 5 extraction stages were sufficient to achieve feed decontamination factors above 2200 and 320 for Am and Cm, respectively. Co-extraction of molybdenum and zirconium, as well as of palladium, were efficiently prevented using oxalic acid and HEDTA scrubbing, respectively. However, technetium, yttrium, and to some extent ruthenium, were co-extracted. The back-extraction proved to be very efficient, yielding in 4 stages more than 99.9% recovery of Am and Cm. The extraction profiles were modeled with computer code simulations and the results compared with data obtained from an experiment using the former reference molecule DMDBTDMA (DiMethylDiButylTetraDecylMalonAmide).
Management of Resistant Hypertension—An Update
Authors: Giacona John M. , Kositanurit Weerapat , Vongpatanasin Wanpen
Published: February 2024

This JAMA Internal Medicine Clinical Insights review provides an update on the current recommendations for resistant hypertension management.
Health Equity in the Veterans Health Administration From Veterans’ Perspectives by Race and Sex
Authors: Lee Natalie S. , Keddem Shimrit , Sorrentino Anneliese E. , Jenkins Kevin Ahmaad , Long Judith A.
Published: February 2024

Importance

Advancing equitable patient-centered care in the Veterans Health Administration (VHA) requires understanding the differential experiences of unique patient groups.

Objective

To inform a comprehensive strategy for improving VHA health equity through the comparative qualitative analysis of care experiences at the VHA among veterans of Black and White race and male and female sex.

Design, Setting, and Participants

This qualitative study used a technique termed freelisting, an anthropologic technique eliciting responses in list form, at an urban academic VHA medical center from August 2, 2021, to February 9, 2022. Participants included veterans with chronic hypertension. The length of individual lists, item order in those lists, and item frequency across lists were used to calculate a salience score for each item, allowing comparison of salient words and topics within and across different groups. Participants were asked about current perceptions of VHA care, challenges in the past year, virtual care, suggestions for change, and experiences of racism. Data were analyzed from February 10 through September 30, 2022.

Main Outcomes and Measures

The Smith salience index, which measures the frequency and rank of each word or phrase, was calculated for each group.

Results

Responses from 49 veterans (12 Black men, 12 Black women, 12 White men, and 13 White women) were compared by race (24 Black and 25 White) and sex (24 men and 25 women). The mean (SD) age was 64.5 (9.2) years. Some positive items were salient across race and sex, including “good medical care” and telehealth as a “comfortable/great option,” as were some negative items, including “long waits/delays in getting care,” “transportation/traffic challenges,” and “anxiety/stress/fear.” Reporting “no impact” of racism on experiences of VHA health care was salient across race and sex; however, reports of race-related unprofessional treatment and active avoidance of race-related conflict differed by race (present among Black and not White participants). Experiences of interpersonal interactions also diverged. “Impersonal/cursory” telehealth experiences and the need for “more personal/attentive” care were salient among women and Black participants, but not men or White participants, who associated VHA care with courtesy and respect.

Conclusions and Relevance

In this qualitative freelist study of veteran experiences, divergent experiences of interpersonal care by race and sex provided insights for improving equitable, patient-centered VHA care. Future research and interventions could focus on identifying differences across broader categories both within and beyond race and sex and bolstering efforts to improve respect and personalized care to diverse veteran populations.
Sublingual Edaravone Dexborneol for the Treatment of Acute Ischemic Stroke
Authors: Fu Yu , Wang Anxin , Tang Renhong , Li Shuya , Tian Xue , Xia Xue , Ren Jinsheng , Yang Shibao , Chen Rong , Zhu Shunwei , Feng Xiaofei , Yao Jinliang , Wei Yan , Dong Xueshuang , Ling Yun , Yi Fei , Deng Qian , Guo Cunju , Sui Yi , Han Shugen , Wen Guoqiang , Li Chuanling , Dong Aiqin , Sun Xin , Wang Zhimin , Shi Xueying , Liu Bo , Fan Dongsheng
Published: February 2024

Importance

Sublingual edaravone dexborneol, which can rapidly diffuse and be absorbed through the oral mucosa after sublingual exposure, is a multitarget brain cytoprotection composed of antioxidant and anti-inflammatory ingredients edaravone and dexborneol.

Objective

To investigate the efficacy and safety of sublingual edaravone dexborneol on 90-day functional outcome in patients with acute ischemic stroke (AIS).

Design, Setting, and Participants

This was a double-blind, placebo-controlled, multicenter, parallel-group, phase 3 randomized clinical trial conducted from June 28, 2021, to August 10, 2022, with 90-day follow-up. Participants were recruited from 33 centers in China. Patients randomly assigned to treatment groups were aged 18 to 80 years and had a National Institutes of Health Stroke Scale score between 6 and 20, a total motor deficit score of the upper and lower limbs of 2 or greater, a clinically diagnosed AIS symptom within 48 hours, and a modified Rankin Scale (mRS) score of 1 or less before stroke. Patients who did not meet the eligibility criteria or declined to participate were excluded.

Intervention

Patients were assigned, in a 1:1 ratio, to receive sublingual edaravone dexborneol (edaravone, 30 mg; dexborneol, 6 mg) or placebo (edaravone, 0 mg; dexborneol, 60 μg) twice daily for 14 days and were followed up until 90 days.

Main Outcomes and Measures

The primary efficacy outcome was the proportion of patients with mRS score of 1 or less on day 90 after randomization.

Results

Of 956 patients, 42 were excluded. A total of 914 patients (median [IQR] age, 64.0 [56.0-70.0] years; 608 male [66.5%]) were randomly allocated to the edaravone dexborneol group (450 [49.2%]) or placebo group (464 [50.8%]). The edaravone dexborneol group showed a significantly higher proportion of patients experiencing good functional outcomes on day 90 after randomization compared with the placebo group (290 [64.4%] vs 254 [54.7%]; risk difference, 9.70%; 95% CI, 3.37%-16.03%; odds ratio, 1.50; 95% CI, 1.15-1.95, P = .003). The rate of adverse events was similar between the 2 groups (89.8% [405 of 450] vs 90.1% [418 of 464]).

Conclusion and Relevance

Among patients with AIS within 48 hours, sublingual edaravone dexborneol could improve the proportion of those achieving a favorable functional outcome at 90 days compared with placebo.

Trial Registration

ClinicalTrials.gov Identifier: NCT04950920
High‐Throughput Ammonia Production from Nitrate Using Liquid Metal Synthesized Bismuth Nano‐Catalyst
Authors: Nazari Sahar , Sun Jing , Baharfar Mahroo , Poulin Philippe , Kalantar‐Zadeh Kourosh , Jalili Ali (Rouhollah) , Esrafilzadeh Dorna
Published: February 2024

The implementation of renewable energy sources to electrify ammonia (NH3) production is identified as a critical approach for achieving successful decarburization in the pursuit of a more sustainable future. A liquid metal‐based method is presented for synthesizing bismuth (Bi) nano‐electrocatalysts, enabling efficient and sustainable ammonia production via nitrate electroreduction. Bi‐metal precipitated from a gallium liquid metal alloy yields solution‐processable Bi and oxide with controllable nanostructures such as nanosheets, nanotubes, and nanoparticles. Combining Bi nano‐electrocatalysts and graphene liquid crystals creates self‐assembling layered electrocatalytic systems. Integrating 3D printing technology allows for precise control over the geometry, microporosity, and number of deposited layers of the electrocatalytic scaffold electrode, resulting in improved mass transport properties, durability, and the prevention of catalyst detachment. Consequently, the ammonia production rate reaches 400 nmol s−1 cm−2, with a Faradaic efficiency of over 90% and current densities exceeding 350 mA cm−2. These numbers indicate the excellent scalability potential of the proposed electrocatalytic system.