bluuebunny/crossref_metadata_2025 huggingface dataset:
Conformational spaces of the gastrointestinal antisecretory chiral drug omeprazole: Stereochemistry and tautomerism
Authors: Caner Hava , Cheeseman James R. , Agranat Israel
Published: October 2005

A study of the conformational spaces of the chiral proton pump inhibitor (PPI) drug omeprazole by semiempirical, ab‐initio, and DFT methods is described. In addition to the chiral center at the sulfinyl sulfur atom, the chiral axis at the pyridine ring (due to the hindered rotation of the 4‐methoxy substituents) was considered. The results were analyzed in terms of the 5‐methoxy and 6‐methoxy tautomers and the two pairs of enantiomers (R,P)/(S,M) and (R,M)/(S,P). Five torsion angles were systematically explored: the backbone rotations defined by D1 (N3–C2–S10–O11), D2 (C2–S10–C12–C13), and D3 (S10–C12–C13–N14) and two methoxy rotations defined by D4 (C6–C5–O8–C9) and D5 (C16–C17–O19–C20). Significant energy differences were revealed between the 5‐ and 6‐methoxy tautomers, the extended and folded conformations, and the (S,M) and (S,P) diastereomers. The “extended M” conformation of the 6‐methoxy tautomer of (S)‐omeprazole was found to be the most stable conformer. © 2005 Wiley‐Liss, Inc. Chirality
In Situ 1H NMR Study on the Trioctylphosphine Oxide Capping of Colloidal InP Nanocrystals
Authors: Hens Zeger , Moreels Iwan , Martins Jose C.
Published: October 2005

We used trioctylphosphine oxide (TOPO) capped colloidal InP nanocrystals (Q‐InP|TOPO) to explore the potential of solution 1H NMR spectroscopy in studying in situ the capping and capping exchange of sterically stabilized colloidal nanocrystals. The spectrum of Q‐InP|TOPO shows resonances of free TOPO, superimposed on broadened spectral features. The latter were assigned to TOPO adsorbed at Q‐InP by means of pulsed field gradient diffusion NMR and 1H‐13C HSQC spectroscopy. The diffusion coefficient of Q‐InP|TOPO nanocrystals was inferred from the decay of the adsorbed TOPO NMR signal. The corresponding hydrodynamic diameter correlates well with the diameter of Q‐InP. By using the resolved methyl resonance of adsorbed TOPO, the packing density of TOPO at the InP surface can be estimated. Spectral hole burning was used to demonstrate explicitly that the adsorbed TOPO resonances are heterogeneously broadened. Exchange of the TOPO capping by pyridine was demonstrated by the disappearance of the resonances for adsorbed TOPO and the appearance of pyridine resonances in the 1H NMR spectrum. These results show that solution NMR spectroscopy should be considered a powerful technique for the in situ study of the capping of sterically stabilized colloidal nanocrystals.
Importin α mRNAs have distinct expression profiles during spermatogenesis
Authors: Hogarth Cathryn A. , Calanni Sophina , Jans David A. , Loveland Kate L.
Published: October 2005

Importin proteins control access to the cell nucleus by mediating the nuclear transport of specific cargoes. We hypothesized that developmental regulation of gene expression may be partially effected by changes in the nuclear transport machinery complement, manifested as regulated expression of importin α family genes. We first clarified the identity of the five known mouse importin α genes relative to those for human and then determined their expression throughout postnatal rodent testis using PCR and in situ hybridization. Distinct expression patterns were observed for each. At 10 dpp, all importin α mRNAs were detected in spermatogonia. In the adult mouse testis,importinsα1andα3were detected in spermatogonia and early pachytene spermatocytes.Importin α4mRNA was identified in pachytene spermatocytes,α6mRNA in round spermatids, andα2mRNA in both of these. The distinct importin α expression patterns are consistent with their having specific roles and transport cargoes during spermatogenesis. Developmental Dynamics 235:253–262, 2006. © 2005 Wiley‐Liss, Inc.
Circadian clock and cell cycle gene expression in mouse mammary epithelial cells and in the developing mouse mammary gland
Authors: Metz Richard P. , Qu Xiaoyu , Laffin Brian , Earnest David , Porter Weston W.
Published: October 2005

Mouse mammary epithelial cells (HC‐11) and mammary tissues were analyzed for developmental changes in circadian clock, cellular proliferation, and differentiation marker genes. Expression of the clock genes Per1 and Bmal1 were elevated in differentiated HC‐11 cells, whereas Per2 mRNA levels were higher in undifferentiated cells. This differentiation‐dependent profile of clock gene expression was consistent with that observed in mouse mammary glands, as Per1 and Bmal1 mRNA levels were elevated in late pregnant and lactating mammary tissues, whereas Per2 expression was higher in proliferating virgin and early pregnant glands. In both HC‐11 cells and mammary glands, elevated Per2 expression was positively correlated with c‐Myc and Cyclin D1 mRNA levels, whereas Per1 and Bmal1 expression changed in conjunction with β‐casein mRNA levels. Interestingly, developmental stage had differential effects on rhythms of clock gene expression in the mammary gland. These data suggest that circadian clock genes may play a role in mouse mammary gland development and differentiation. Developmental Dynamics 235:263–271, 2006. © 2005 Wiley‐Liss, Inc.
A 3′ cis‐regulatory region controls wingless expression in the Drosophila eye and leg primordia
Authors: Pereira P.S. , Pinho S. , Johnson K. , Couso J.P. , Casares F.
Published: October 2005

The precise regulation of wingless (wg) expression in the Drosophila eye disc is key to control the anteroposterior and dorsoventral patterning of this disc. Here, we identify an eye disc‐specific wg cis‐regulatory element that functions as a regulatory rheostat. Pannier (Pnr), a transcription factor previously proposed to act as an upstream activator of wg, is sufficient to activate the eye disc enhancer but required for wg expression only in the peripodial epithelium of the disc. We propose that this regulation of wg by Pnr appeared associated to the development of the peripodial epithelium in higher dipterans and was added to an existing mechanism regulating the deployment of wingless in the dorsal region of the eye primordium. In addition, our analysis identifies a separate ventral disc enhancer that lies adjacent to the eye‐specific one, and thus altogether, they define a 1‐kb genomic region where disc‐specific enhancers of the wg gene are located. Developmental Dynamics 235:225–234, 2006. © 2005 Wiley‐Liss, Inc.
Copolymer effects on microglia and T cells in the central nervous system of humanized mice
Authors: Illes Zsolt , Stern Joel N. H. , Keskin Derin B. , Reddy Jayagopala , Brosnan Celia F. , Waldner Hanspeter , Santambrogio Laura , Kuchroo Vijay K. , Strominger Jack L.
Published: October 2005

The random amino acid copolymers FYAK and VWAK ameliorate EAE in a humanized mouse model expressing both a human transgenic myelin basic protein (MBP)85–99‐specific T cell receptor and HLA‐DR2. Here we show that microglia isolated from the central nervous system (CNS) of humanized mice with EAE induced by MBP85–99 and treated with these copolymers had reduced expression of HLA‐DR, and thus reduced capacity to present MBP85–99 and activate transgenic T cells. In vitro microglia up‐regulated empty HLA‐DR2 upon activation with GM‐CSF with or without LPS or IFN‐γ, but not with IL‐4 or IL‐10. Correspondingly, gene chip arrays showed that the CNS of untreated and YFAK‐treated mice differentially expressed pro‐ and anti‐inflammatory molecules during MBP85–99‐induced EAE. Interestingly, microglia expressed the full‐length γβ and αβ subunits of the tetrameric adaptor protein complexes AP‐1 and AP‐2 respectively, but after treatment with GM‐CSF these complexes were cleaved, as had been found in immature dendritic cells derived from bone marrow. Strikingly, in vivo the perivascular lymphocyte infiltration seen in untreated mice immunized with MBP85–99 was composed of equal numbers of hVβ2+ MPB85–99‐specific transgenic and hVβ2– endogenous T cells, while the much smaller infiltration seen after treatment with YFAK was composed predominantly of hVβ2– endogenous T cells.
Genetic control of thymic development of CD4+CD25+FoxP3+ regulatory T lymphocytes
Authors: Romagnoli Paola , Tellier Julie , van Meerwijk Joost P. M.
Published: October 2005

Among the several mechanisms known to be involved in the establishment and maintenance of immunological tolerance, the activity of CD4+CD25+ regulatory T lymphocytes has recently incited most interest because of its critical role in inhibition of autoimmunity and anti‐tumor immunity. Surprisingly, very little is known about potential genetic modulation of intrathymic regulatory T lymphocyte development. We show that distinct proportions of CD4+CD25+FoxP3+ regulatory T cells are found in thymi of common laboratory mouse strains. We demonstrate that distinct levels of phenotypically identical regulatory T cells develop with similar kinetics in the mice studied. Our experimental data on congenic mouse strains indicate that differences are not caused by the distinct MHC haplotypes of the inbred mouse strains. Moreover, the responsible loci act in a thymocyte‐intrinsic manner, confirming the latter conclusion. We have not found any correlation between thymic and peripheral levels of regulatory T cells, consistent with known homeostatic expansion and/or retraction of the peripheral regulatory T cell pool. Our data indicate that polymorphic genes modulate differentiation of regulatory T cells. Identification of responsible genes may reveal novel clinical targets and still elusive regulatory T cell‐specific markers. Importantly, these genes may also modulate susceptibility to autoimmune disease.
Assessment of the Reusability of Pd Complexes Supported on Fluorous Silica Gel as Catalysts for Suzuki Couplings
Authors: Tzschucke Carl Christoph , Andrushko Vasyl , Bannwarth Willi
Published: October 2005

A thorough investigation of different perfluoro‐tagged Pd complexes supported on fluorous silica gel (FSG) as catalysts for Suzuki reactions is presented. The rates of reaction upon recycling of the supported complexes were measured in order to determine the reusability of the catalysts. Perfluoro‐tagged and untagged complexes adsorbed on FSG and unmodified silica gel were also compared. While with dimethoxyethane (DME) as a solvent the catalytic activity decreased upon reuse, significant activity was retained with recycled catalysts for reactions in water. With catalyst loadings of 0.001 mol‐%, TONs as high as 526000 were obtained. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Solution‐Phase Synthesis of Phosphorothioate Oligonucleotides Using a Solid‐Supported Acyl Chloride with H‐Phosphonate Chemistry
Authors: Adamo Ilaria , Dueymes Cécile , Schönberger Andreas , Navarro Aude‐Emmanuelle , Meyer Albert , Lange Meinolf , Imbach Jean‐Louis , Link Fritz , Morvan François , Vasseur Jean‐Jacques
Published: October 2005

The synthesis of oligonucleotides from dimers to a hexamer by a H‐phosphonate approach in solution using solid‐supported acyl chloride is reported herein. This strategy avoids the use of chromatography. The work‐ups have been simplified and involve filtration, aqueous extraction and precipitation. The synthesis was scaled up to 1 mmol for the dimers and 340 μmol for the hexamer. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Electrochemical Response of Cobalt(II) in the Presence of Ammonia
Authors: Ji Xiaobo , Buzzeo Marisa C. , Banks Craig E. , Compton Richard G.
Published: October 2005

The electrochemical oxidation of cobalt(II) at gold, boron‐doped diamond, basal and edge plane pyrolytic graphite, and highly oriented pyrolytic graphite electrodes in aqueous solutions containing NH3 has been studied using cyclic voltammetry, with subsequent chemical and electrochemical processes explained in detail. Furthermore, the electro‐reduction of [Co(NH3)6]3+ in the presence of different electrolytes has also been studied to obtain a better understanding of the oxidation pathway of the Co(II)‐ammine complexes. In aqueous solution the mechanism can be described by the following scheme:
Sometimes more equal than others: how health inequalities depend on the choice of welfare indicator
Authors: Lindelow Magnus
Published: October 2005

In recent years, a large body of empirical work has focused on measuring and explaining socio‐economic inequalities in health outcomes and health service use. In any effort to address these questions, analysts must confront the issue of how to measure socioeconomic status. In developing countries, socioeconomic status has typically been measured by per capita consumption or an asset index. Currently, there is only limited information on how the choice of welfare indicators affect the analysis of health inequalities and the incidence of public spending. The purpose of this paper is to illustrate the potential sensitivity of the analysis of health related inequalities to how socioeconomic status is measured. Using data from Mozambique, the paper focuses on five key health service indicators, and tests whether measured inequality (concentration index) in health service utilization differs depending on the choice of welfare indicator. The paper shows that, at least in some contexts, the choice of welfare indicator can have a large and significant impact on measured inequality in utilization of health services. In consequence, we can reach very different conclusions about the ‘same’ issue depending on how we define socioeconomic status. The paper also provides some tentative conclusions about why and in what contexts health inequalities can be sensitive to the choice of living standards measure. The results call for more clarity and care in the analysis of health related inequalities, and for explicit recognition of the potential sensitivity of findings to the choice of welfare measure. The results also point at the need for more careful research on how different dimensions of SES are related, and on the pathways by which the respective different dimensions impact on health related variables. Copyright © 2005 John Wiley & Sons, Ltd.
Responses of excitatory hippocampal synapses to natural stimulus patterns reveal a decrease in short‐term facilitation and increase in short‐term depression during postnatal development
Authors: deKay James G.T. , Chang Tony C. , Mills Nadia , Speed Haley E. , Dobrunz Lynn E.
Published: October 2005

Schaffer collateral excitatory synapses onto CA1 pyramidal cells are subject to significant modulation by short‐term plasticity. This presynaptic, history‐dependent modulation of neurotransmitter release causes synaptic transmission to be sensitive to the frequency of the input. As a result, temporally irregular input patterns, such as those observed in vivo, produce synaptic responses over a very wide dynamic range that reflect a balance of short‐term facilitation and short‐term depression. The neonatal period is an important developmental period in the hippocampus, when functional representations of an animal's environment are being established through exploratory behavior. The strength of excitatory synapses and their modulation by short‐term plasticity are critical to this process. One form of short‐term plasticity, paired‐pulse facilitation, has been shown to decrease as juvenile rats mature into young adults. However, little is known about the neonatal modulation of other forms of short‐term plasticity, including the responses to temporally complex stimuli. We examined developmental modulation of the short‐term dynamics of Schaffer collateral excitatory synapses onto CA1 pyramidal cells in acute hippocampal slices, using both constant frequency stimuli and natural stimulus patterns that were taken from in vivo recording of spike patterns of hippocampal cells. In response to constant frequency stimulation, synapses in slices from young adult rats (P28–P35) showed less short‐term depression than did those in slices from juveniles (P12–P18). However, when the natural stimulus pattern (containing a wide mix of frequencies) was used, synapses from young adults instead showed more short‐term depression and less short‐term facilitation than did juveniles. Comparing the natural stimulus pattern responses with constant frequency stimulation of a similar frequency, we found that the average responses were similar in young adults (both showed modest depression). However, in juveniles, the natural pattern produced robust facilitation while constant frequency stimulation caused a large short‐term depression. Our results reveal that there are developmental changes both in individual forms of short‐term plasticity and in the relative balance between short‐term facilitation and short‐term depression that will alter the signal transfer characteristics of these synapses. © 2005 Wiley‐Liss, Inc.
Estimating amount and spatial distribution of groundwater recharge in the Iullemmeden basin (Niger) based on 3H, 3He and CFC‐11 measurements
Authors: Rueedi J. , Brennwald M. S. , Purtschert R. , Beyerle U. , Hofer M. , Kipfer R.
Published: October 2005

A new approach is presented to estimate the amounts and spatial distribution of groundwater recharge based on the groundwater dating tracers 3H, 3He and CFC‐11. The method was applied in a groundwater project in southwest Niger (Africa). The model developed to simulate observed tracer concentrations is composed of a model to account for the water transported through the unsaturated zone followed by a dispersion box model to determine the age distribution of the sampled groundwater volume. For the unsaturated zone transport, a one‐dimensional approach was used considering tracer transport in the water and the gas phase. The calculated tracer concentrations at the groundwater table are then used as input functions for the subsequent dispersion box model. Using a dispersion box model it is possible to outline regions where recharge preferably occurs. To account for the high variance of soil properties in space, a Monte Carlo simulation was performed.

The results show estimated recharge rates of 50–300 mm year−1 (±50%). The large error bars are mainly due to high uncertainties of the soil parameters. Therefore, a better estimation of the average soil moisture would lead to more accurate results. The resulting spatial distribution of dispersion parameters indicates that recharge mainly occurs in the ancient riverbeds where surface runoff from the laterite plateaux is gathered and leads to spatially limited high recharge events. Where the soil is not permeable enough, these events lead to the observed temporary or permanent lakes. This new conceptual view of major recharge mechanisms contradicts the former picture of recharge occurring in this region, but it coincides better with other independent measurements, such as the stable isotope ratios of water. Copyright © 2005 John Wiley & Sons, Ltd.
Tritium balance modelling in a macroscale catchment
Authors: Koeniger P. , Wittmann S. , Leibundgut Ch. , Krause W. J.
Published: October 2005

Tritium concentrations measured in precipitation and discharge are combined with hydrological and meteorological information on a monthly basis over a period of 50 years in order to study tritium balances and hydrological interactions in macroscale catchments. Three subcatchments of the Weser River in Germany (Werra 5410 km2, Fulda 6890 km2 and Weser‐1 15 320 km2) were used to test a tritium balance model, to study residence times, groundwater storage behaviour and tritium load of different water balance components. A comparison of measured and modelled tritium concentrations in discharge showed considerable fits with model efficiencies close to 0·7. The estimated residence times for an estimated fast and slow groundwater component are between 5 to 8 years and 7 to 28 years respectively. The results indicate a tritium load of 12 to 14% of the precipitation input over the whole time period moving through groundwater reservoirs and 13 to 16% transported through direct discharge. Copyright © 2005 John Wiley & Sons, Ltd.
Tracing long‐term vadose zone processes at the Nevada Test Site, USA
Authors: Hunt James R. , Tompson Andrew F. B.
Published: October 2005

The nuclear weapons testing programme of the USA has released radionuclides to the subsurface at the Nevada Test Site. One of these tests has been used to study the hydrological transport of radionuclides for over 25 years in groundwater and the deep unsaturated zone. Ten years after the weapon's test, a 16 year groundwater pumping experiment was initiated to study the mobility of radionuclides from that test in an alluvial aquifer. The continuously pumped groundwater was released into an unlined ditch where some of the water infiltrated into the 200 m deep vadose zone. The pumped groundwater had well‐characterized tritium activities that were utilized to trace water migration in the shallow and deep vadose zones. Within the near‐surface vadose zone, tritium levels in the soil water are modelled by a simple one‐dimensional, analytical wetting front model. In the case of the near‐surface soils at the Cambric Ditch experimental site, water flow and salt accumulation appear to be dominated by rooted vegetation, a mechanism not included within the wetting front model. Simulation results from a two‐dimensional vadose groundwater flow model illustrate the dominance of vertical flow in the vadose zone and the recharge of the aquifer with the pumped groundwater. The long‐time series of hydrological data provides opportunities to understand contaminant transport processes better in the vadose zone with an appropriate level of modelling. Copyright © 2005 John Wiley & Sons, Ltd.
Assessment of peat compressibility: is there an easy way?
Authors: Price Jonathan S. , Cagampan Jason , Kellner Erik
Published: October 2005

Peat compression can significantly alter the hydraulic parameters that govern flow and storage of water. Physical properties of peat (bulk density, state of decomposition (von Post number, vP) and fibre content) were assessed to determine whether they can be used as indicators of peat compressibility. Bulk density and vP were related to each other (positively), and within a given core were related (negatively) to compressibility. Peat from different locations exhibited different compressibility characteristics for a given value of bulk density or vP. Fibre content was unrelated to bulk density, vP, or to peat compressibility. It was concluded that more commonly and relatively easily measured soil parameters are not good indicators of soil compressibility. Copyright © 2005 John Wiley & Sons, Ltd.
Recognition of tandem sialic acid residues by CD38: A theoretical study
Authors: Ueno‐Noto Kaori , Hara‐Yokoyama Miki , Takano Keiko
Published: October 2005

The electronic structures of gangliosides are described using semiempirical and ab inito molecular orbital theories as well as the density functional theory to clarify the causative factors of the differences in inhibitory effects and to elucidate the recognition mechanisms of the enzyme. Our results suggest that CD38 is likely to recognize the two phosphate groups in NAD and the two carboxyl groups in tandem sialic acid residues of gangliosides. The recognition mechanisms of the substrate are proposed based on the good correlation found between the orbital energy of the highest occupied molecular orbital of the gangliosides and the degree of the inhibitory effect. © 2005 Wiley Periodicals, Inc. J Comput Chem 27: 53–60, 2006
Accurate relativistic adapted Gaussian basis sets for hydrogen through xenon without variational prolapse and to be used with both uniform sphere and Gaussian nucleus models
Authors: Haiduke Roberto L.A. , da Silva Albérico B.F.
Published: October 2005

Accurate relativistic adapted Gaussian basis sets (RAGBSs) from H (Z = 1) through Xe (Z = 54) without variational prolapse have been developed by employing a polynomial version of the Generator Coordinate Dirac‐Fock (p‐GCDF) method. Two nuclear models have been used in this work: (1) the finite nucleus of uniform proton‐charge distribution, and (2) the finite nucleus with a Gaussian proton–charge distribution. The largest errors observed are only 1.5 mHartree (silver and cadmium) and the RAGBS sizes are much smaller than previous accurate relativistic Gaussian basis sets that were shown to be free of variational prolapse. © 2005 Wiley Periodicals, Inc. J Comput Chem 27: 61–71, 2006
Mitochondrial activity regulates myoblast differentiation by control of c‐Myc expression
Authors: Seyer Pascal , Grandemange Stéphanie , Busson Muriel , Carazo Angel , Gamaléri Frédéric , Pessemesse Laurence , Casas François , Cabello Gérard , Wrutniak‐Cabello Chantal
Published: October 2005

We have previously shown that mitochondrial activity is an important regulator of myoblast differentiation, partly through processes targeting myogenin expression. Here, we investigated the possible involvement of c‐myc in these processes. Inhibition of mitochondrial activity by chloramphenicol abrogated the decrease in c‐myc mRNA and protein levels occurring at the onset of terminal differentiation. Conversely, stimulation of mitochondrial activity by overexpression of the T3 mitochondrial receptor (p43) down‐regulated c‐myc expression. In addition, c‐myc overexpression mimicked the influence of mitochondrial activity inhibition on myoblast differentiation. Moreover, like chloramphenicol, c‐myc overexpression strongly inhibited the myogenic influence of p43 overexpression. These data suggest that c‐Myc is an important target of mitochondrial activity involved in the myogenic influence of the organelle. Lastly, we found that chloramphenicol influence is negatively related to the frequency of post‐mitotic myoblasts in the culture at the onset of treatment, and cell cycle analyses demonstrated that the frequency of myoblasts in G0–G1 phase at cell confluence is increased by p43 overexpression and decreased by chloramphenicol or c‐myc overexpression. These results suggest that irreversible myoblast withdrawal from the cell cycle is a target of mitochondrial activity by control of c‐Myc expression. J. Cell. Physiol. 207: 75–86, 2006. © 2005 Wiley‐Liss, Inc.
Arterial spin labeling: Validity testing and comparison studies
Authors: Ewing James R. , Cao Yue , Knight Robert A. , Fenstermacher Joseph D.
Published: October 2005

Arterial spin labeling (ASL) is a potential means of obtaining quantitative images of cerebral blood flow (CBF). However, few validation studies of ASL have been performed in animal models using gold‐standard CBF methods. Other methods that use radiolabeled water as a tracer underestimate CBF in high flow states, but this effect has not been evident in ASL studies. In this study the accuracy of ASL measurements of CBF were modeled and experimentally validated, with particular attention paid to high flow rates. The ASL signal as modeled included the contributions from intravascular labeled spins. The modeling demonstrated linearity of the ASL signal with respect to baseline flow, and linearity of ASL signal changes with respect to changes in flow, including high‐flow conditions. Validation studies using quantitative autoradiography (QAR) to image flow in a rat model of unilateral cerebral ischemia showed that ASL systematically overestimated CBF by 34%. A similar overestimation was also predicted by modeling. These results indicate that ASL signals are linear with respect to flow (even high flow), but ASL‐CBF measurements are systematically overestimated. J. Magn. Reson. Imaging 2005. © 2005 Wiley‐Liss, Inc.
Partial volume effects on arterial input functions: Shape and amplitude distortions and their correction
Authors: van Osch Matthias J.P. , van der Grond Jeroen , Bakker Chris J.G.
Published: October 2005

For quantification of perfusion values from a bolus‐tracking MRI experiment, the measurement of an arterial input function (AIF) is necessary. Gradient‐echo (GE) sequences are commonly used for this type of experiment because they offer a high signal‐to‐noise ratio (SNR) and the potential to quantify the concentration of contrast agent. Measurements of calibration curves for Gd‐DTPA in human blood have shown a quadratic relation between the ΔR2* and the concentration of contrast agent, and a linear relationship between phase changes and the concentration of contrast agent. However, for in vivo studies the spatial resolution is usually limited, which leads to partial volume effects. Partial volume effects result in a complex sum of signal arising from the tissue outside the vessel and a contrast agent concentration‐dependent blood signal. Ignoring the presence of partial volume effects can lead to an overestimation or underestimation of the contrast agent concentration, depending on the experimental conditions. Correction for partial volume effects is feasible in arteries that are parallel to the main magnetic field by estimation and subtraction of the static signal of the surrounding tissue. Patient studies showed a large variation due to the AIF measurements, but it has also been shown that this influence can be minimized by correction for partial volume effects. J. Magn. Reson. Imaging 2005. © 2005 Wiley‐Liss, Inc.
Quantifying CBF with pulsed ASL: Technical and pulse sequence factors
Authors: Wong Eric C.
Published: October 2005

We summarize here current methods for the quantification of CBF using pulsed arterial spin labeling (ASL) methods. Several technical issues related to CBF quantitation are described briefly, including transit delay, signal from larger arteries, radio frequency (RF) slice profiles, magnetization transfer, tagging efficiency, and tagging geometry. Many pulsed tagging schemes have been devised, which differ in the type of tag or control pulses, and which have various advantages and disadvantages for quantitation. Several other modifications are also available that can be implemented as modules in an ASL pulse sequence, such as varying the wash‐in time to estimate the transit delay. Velocity‐selective ASL (VS‐ASL) uses a new type of pulse labeling in which inflowing arterial spins are tagged based on their velocity rather than their spatial location. In principle, this technique may allow ASL measurement of cerebral blood flow (CBF) that is insensitive to transit delays. J. Magn. Reson. Imaging 2005. © 2005 Wiley‐Liss, Inc.
Microwave Accelerated Polymerization of 2‐Phenyl‐2‐oxazoline: Microwave or Temperature Effects?
Authors: Hoogenboom Richard , Leenen Mark A. M. , Wiesbrock Frank , Schubert Ulrich S.
Published: October 2005

Summary: Investigations regarding the cationic ring‐opening polymerization of 2‐phenyl‐2‐oxazoline under microwave irradiation and conventional heating are reported. This study was inspired by contradictory reports of the (non‐)existence of non‐thermal microwave effects that might accelerate the cationic ring‐opening of 2‐oxazolines. The polymerization of 2‐phenyl‐2‐oxazoline was investigated under pressure in acetonitrile and under reflux (or at the boiling point of butyronitrile in a closed vessel) in butyronitrile utilizing a single‐mode microwave reactor and automated synthesis robots with conventional heating.

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Novel Semiconducting Polymer Particles by Supercritical Fluid Process
Authors: Lim Kwon Taek , Subban Ganapathy Hullathy , Hwang Ha Soo , Kim Jung Taek , Ju Chang Sik , Johnston Keith P.
Published: October 2005

Summary: A simple method to prepare surfactant‐free and solvent‐free semiconducting polymer particles by using an environmentally benign supercritical carbon dioxide (scCO2) process is reported. The process of the rapid expansion of supercritical solutions (RESS) is used to produce spherical particles of poly[2‐(3‐thienyl)acetyl 3,3,4,4,5,5,6,6,7,7,8,8,8‐tridecafluorooctanoate] (PSFTE), 50–500 nm in size, from 0.1–0.5 wt.‐% PSFTE solutions in CO2 at pre‐expansion temperatures of 40 °C and pre‐expansion pressures of 276 bar.

An FESEM image of PSFTE particles produced by the RESS process with CO2.

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An FESEM image of PSFTE particles produced by the RESS process with CO2.
On the Use of the Nanoindentation Unloading Curve to Measure the Young's Modulus of Polymers on a Nanometer Scale
Authors: Tranchida Davide , Piccarolo Stefano
Published: October 2005

Summary: The nanoindentation test is a fundamental tool to assess the link between morphology and mechanical properties. The preliminary results of a more exhaustive study about the applicability to polymers of the most used procedure to determine elastic modulus by indentation are reported in this short communication. A departure of the experimental conditions from the theoretical assumptions and results that give rise to the Oliver and Pharr analysis is shown to occur under a wide range of experimental conditions, with applied loads and penetration depths covering several orders of magnitude and using different indenter geometries. Unloading curves with exponents significantly larger than 2 are observed in disagreement with the contact mechanics approach used by Oliver and Pharr.

An AFM image obtained in non contact mode of an indentation induced by a sharp AFM tip with a maximum applied load of ca 1.2 µN on amorphous PET.

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An AFM image obtained in non contact mode of an indentation induced by a sharp AFM tip with a maximum applied load of ca 1.2 µN on amorphous PET.
Polymerization of Enantiomerically Pure exo‐N‐(Norborn‐2‐ene‐5‐carboxyl)‐L‐phenylalanine Ethyl Ester and endo,endo‐N,N‐(Norborn‐5‐ene‐2,3‐dicarbimido)‐L‐valine Ethyl Ester Using Novel Ruthenium 1,3‐Dimesityl‐3,4,5,6‐tetrahydropyrimidin‐2‐ylidenes
Authors: Wang Dongren , Yang Liangru , Decker Ulrich , Findeisen Matthias , Buchmeiser Michael R.
Published: October 2005

Summary: The polymerization of two chiral, enantiomerically pure monomers, i.e., exo‐N‐(norborn‐2‐ene‐5‐carboxyl)‐L‐phenylalanine ethyl ester (1) and endo,endo‐N,N‐(norborn‐5‐ene‐2,3‐dicarbimido)‐L‐valine ethyl ester (2) using the ruthenium‐based, 1,3‐dimesityl‐3,4,5,6‐tetrahydropyrimidin‐2‐ylidene (Mes2‐THP)‐derived initiators RuCl2(Mes2‐THP)(CH‐2‐(2‐PrO‐)‐5‐NO2C6H3) (3) and RuCl2(Mes2‐THP)(CHC6H5)(pyridine) (4), is described. Polymerization of 1 mediated by either 3 or 4 proceeded in a living manner with good control over molecular weight. The polymerization of 2 mediated by either 3 or 4 yielded a polymer with an exclusive all‐trans structure.

Structure of the RuCl2(Mes2‐THP)(CHC6H5)(pyridine) (4) catalyst synthesized here.

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Structure of the RuCl2(Mes2‐THP)(CHC6H5)(pyridine) (4) catalyst synthesized here.
Compulsive eating and weight gain related to dopamine agonist use
Authors: Nirenberg Melissa J. , Waters Cheryl
Published: October 2005

Dopamine agonists have been implicated in causing compulsive behaviors in patients with Parkinson's disease (PD). These have included gambling, hypersexuality, hobbyism, and other repetitive, purposeless behaviors (“punding”). In this report, we describe 7 patients in whom compulsive eating developed in the context of pramipexole use. All of the affected patients had significant, undesired weight gain; 4 had other comorbid compulsive behaviors. In the 5 patients who lowered the dose of pramipexole or discontinued dopamine agonist treatment, the behavior remitted and no further weight gain occurred. Physicians should be aware that compulsive eating resulting in significant weight gain may occur in PD as a side‐effect of dopamine agonist medications such as pramipexole. Given the known risks of the associated weight gain and obesity, further investigation is warranted. © 2005 Movement Disorder Society
Determination of the hyperfine coupling constant and zero‐field splitting in the ESR spectrum of Mn2+ in calcite
Authors: Garribba Eugenio , Micera Giovanni
Published: October 2005

The hyperfine coupling constant (A in units of energy or A′ in units of magnetic field) and zero‐field splitting (D in units of energy or D′ in units of magnetic field) in the ESR spectrum of Mn2+ in calcite were determined. The spreading of the non‐central allowed transitions |3/2, m〉 → |5/2, m〉, |1/2, m〉 → |3/2, m〉, |−3/2, m〉 → |−1/2, m〉 and |−5/2, m〉 → |−3/2, m〉 was analysed and the experimental transitions were attributed. Particular relevance was given to the difference between the two types of resonances, shoulder or divergence, and to their origin (M, m). The analysis explains the presence of a weak shoulder between each of the five central doublets |−1/2, m〉 → |1/2, m〉. Six independent methods for calculating the hyperfine coupling constant and five methods for calculating the zero‐field splitting, based on the analysis of the allowed and forbidden transitions, were provided. The values of the hyperfine coupling constant range from −93.9 to −94.6 G and those of the zero‐field splitting range from −79.5 to −80.5 G. A critical evaluation of the advantages and drawbacks of the 11 methods is included: the best value for A′ is −94.30 G and that for D′ is −79.95 G. Copyright © 2005 John Wiley & Sons, Ltd.
Eremophilane esters of Robinsonecio gerberifolius and their rearranged products. Study of the coupling constants 2JH, H, 3JH, H and 4JH, H
Authors: Arciniegas Amira , Pérez‐Castorena Ana‐L. , Cuevas Gabriel , del Río‐Portilla Federico , de Vivar Alfonso Romo
Published: October 2005

In the course of the basic hydrolysis of four eremophilane esters isolated from Robinsonecio gerberifolius, some rearrangements, eliminations, and additions occurred. Five compounds were obtained, three of them not previously described. Additionally, a new sesquiterpene was produced by autooxidation of compound 1. The 1H and 13C NMR spectra of these compounds were completely assigned by utilization of HMQC, HMBC, COSY, DEPT, and NOESY techniques. The long‐range coupling constants of the peroxide 10 are reported, and all its coupling constants 2JH, H, 3JH, H, and 4JH, H are calculated at the B3LYP/6‐31G(d,p) level of theory. Their magnitude is explained in terms of electronic delocalization and the additivity of stereoelectronic effects. Copyright © 2005 John Wiley & Sons, Ltd.
Complete assignment of 1H and 13C NMR data of dihydroxyflavone derivatives
Authors: Moon Byoung‐Ho , Lee Youngshim , Ahn Joong‐Hoon , Lim Yoongho
Published: October 2005

Six flavone derivatives were studied. Previously reported NMR data of three of these derivatives were corrected and the NMR data for the other three derivatives not studied previously were completely assigned on the basis of the basic 1D and 2D NMR experiments and molecular modeling. Copyright © 2005 John Wiley & Sons, Ltd.
Different types of hydrogen bonds in 2‐substituted pyrroles and 1‐vinyl pyrroles as monitored by 1H, 13C and 15N NMR spectroscopy and ab initio calculations
Authors: Afonin Andrei V. , Ushakov Igor A. , Sobenina Lyubov' N. , Stepanova Zinaida V. , Petrova Ol'ga V. , Trofimov Boris A.
Published: October 2005

According to the 1H, 13C and 15N NMR spectroscopic data and ab initio calculations, the strong NH···O intramolecular hydrogen bond in the Z‐isomers of 2‐(2‐acylethenyl)pyrroles causes the decrease in the absolute size of the 1J(N,H) coupling constant by 2 Hz in CDCl3 and by 4.5 Hz in DMSO‐d6, the deshielding of the proton and nitrogen by 5–6 and 15 ppm, respectively, and the lengthening of the NH link by 0.025 Å. The NH···N intramolecular hydrogen bond in the 2(2′‐pyridyl)pyrrole leads to the increase of the 1J(N,H) coupling constant by 3 Hz, the deshielding of the proton by 1.5 ppm and the lengthening of the NH link by 0.004 Å. The CH···N intramolecular hydrogen bond in the 1‐vinyl‐2‐(2′‐pyridyl)‐pyrrole results in the increase of the 1J(C,H) coupling constant by 5 Hz, the deshielding of the proton by 1 ppm and the shortening of the CH link by 0.003 Å. Different behavior of the coupling constants and length of the covalent links under the hydrogen bond influence originate from the different nature of the hydrogen bonding (predominantly covalent or electrostatic), which depends in turn on the geometry of the hydrogen bridge. The Fermi‐contact mechanism only is responsible for the increase of the coupling constant in the case of the predominantly electrostatic hydrogen bonding, whereas both Fermi‐contact and paramagnetic spin‐orbital mechanisms bring about the decrease of coupling constant in the case of the predominantly covalent hydrogen bonding Copyright © 2005 John Wiley & Sons, Ltd.
1H and 19F PGSE diffusion and HOESY NMR studies on cationic palladium (II) 1,3‐diphenylallyl complexes in THF solution
Authors: Fernández Ignacio , Pregosin Paul S.
Published: October 2005

THF solutions of the cationic chiral 1,3‐diphenylallyl bidentate phosphine complexes [Pd(η3‐PhCHCHCHPh)(Duphos)](CF3SO3), Duphos = 1,2‐Bis‐((2R,5R)‐2,5‐dimethylphospholano)benzene), 2, and [Pd(η3‐PhCHCHCHPh)(P,S)]BF4, 4, P,S = [8‐((o‐(diphenylphosphino)benzyl) thiomethyl]—(7,7′‐dimethyl)‐exo‐norborneol, have been studied via pulsed gradient spin‐echo (PGSE) diffusion, 1H, 19F HOESY and a variety of other multi‐dimensional NMR methods. On the basis of the 1H, 19F HOESY data, the anions show a preference for a specific structural position with respect to the η3‐PhCHCHCHPh allyl ligand, i.e. the anion does not move evenly around the periphery of the cation. THF is shown to promote significant ion pairing, although neither 2 nor 4 shows 100% ion pairing. Copyright © 2005 John Wiley & Sons, Ltd.
Transcription of ribosomal RNA genes is initiated in the third cell cycle of bovine embryos
Authors: Jakobsen Anne S. , Avery Birthe , Dieleman Steph J. , Knijn Hiemke M. , Vos Peter L.A.M. , Thomsen Preben D.
Published: October 2005

Transcription from the embryos own ribosomal genes is initiated in most species at the same time as the maternal‐embryonic transition. Recently data have indicated that a minor activation may take place during the third embryonic cell cycle in the bovine, one cell cycle before the major activation of the embryonic genome. In the present study, ribosomal RNA (rRNA) transcription was investigated by visualization of the rRNA by fluorescent in situ hybridization, and subsequent visualization of the argyrophilic nucleolar proteins by silver staining. A total of 145 in vivo developed and 200 in vitro produced bovine embryos were investigated to allow comparison of transcription initiation. Signs of active transcription of rRNA were observed in the third cell cycle in 29% of the in vitro produced embryos (n = 35) and in 58% of the in vivo developed embryos (n = 11). Signs of active transcription of rRNA were not apparent in the early phase of the fourth cell cycle but restarted later on. All embryos in the fifth or later cell cycles were all transcribing rRNA. The signs of rRNA synthesis during the third and fourth embryonic cell cycle could be blocked by actinomycin D, which is a strong inhibitor of RNA polymerase I. In conclusion, rRNA transcription is initiated during the third cell cycle at a low level in both in vivo developed and in vitro produced bovine embryos. Transcription seems to be interrupted during the G1 phase of the fourth cell cycle, but reinitiates in the late half of the cycle and persists during subsequent cell cycles. Mol. Reprod. Dev. © 2005 Wiley‐Liss, Inc.
Expression of aquaporins in the efferent ductules, sperm counts, and sperm motility in estrogen receptor‐α deficient mice fed lab chow versus casein
Authors: Ruz Ricardo , Gregory Mary , Smith Charles E. , Cyr Daniel G. , Lubahn Dennis B. , Hess Rex A. , Hermo Louis
Published: October 2005

Estrogens play an important role in the male reproductive tract, and this is especially so for the efferent ductules, where α‐estrogen receptors (ERα) have been localized. Mice deficient in ERα (αERKO mice) are infertile, and the effect appears to be due in part to retention of water at the level of the efferent ductules. In the present study, we examined the consequences of ERα deletion on the distribution of certain aquaporins (AQPs), water protein channels, in the efferent ductules and on sperm numbers and motility. In addition, the effects of feeding mice a regular lab chow diet, which contains phytoestrogens, known to affect male reproductive tract functions, and a casein diet, which lacks phytoestrogens, were also assessed. Light microscope immunolocalizations of AQP‐1 and AQP‐9 revealed dramatic reduction and patchier staining in αERKO mice with distal areas of the efferent ductules being more affected than proximal areas. No other changes in immunolocalizations were noted as a consequence of diet. Computer‐assisted sperm analyses demonstrated a 62% reduction in cauda epididymal sperm/ml in αERKO mice fed lab chow, whereas 87% fewer sperm/ml were observed in αERKO mice fed casein, suggesting an enhanced role for sperm production and concentration in a diet containing phytoestrogens. All sperm motility parameters were altered to some degree in αERKO mice fed lab chow. Alterations in sperm motility parameters were also detected, but were less dramatic in αERKO mice fed casein. These data suggest that the decrease in AQP expression in the efferent ductules of αERKO mice contributes in part to water retention in this tissue, eventually leading to backflow of water into the testis, with subsequent decreases in sperm concentration and motility. The data also suggest that phytoestrogens, which are present in regular lab chow, can influence the male reproductive tract with and without the presence of ERα, promoting efferent ductule and epididymal functions when ERα is expressed, but inhibiting these same functions when ERα is missing. Taken together the data underscore the importance of estrogens and ERα in maintaining sperm maturation and preventing male infertility. Mol. Reprod. Dev. © 2005 Wiley‐Liss, Inc.
Image reconstruction in SNR units: A general method for SNR measurement†
Authors: Kellman Peter , McVeigh Elliot R.
Published: October 2005

The method for phased array image reconstruction of uniform noise images may be used in conjunction with proper image scaling as a means of reconstructing images directly in SNR units. This facilitates accurate and precise SNR measurement on a per pixel basis. This method is applicable to root‐sum‐of‐squares magnitude combining, B1‐weighted combining, and parallel imaging such as SENSE. A procedure for image reconstruction and scaling is presented, and the method for SNR measurement is validated with phantom data. Alternative methods that rely on noise only regions are not appropriate for parallel imaging where the noise level is highly variable across the field‐of‐view. The purpose of this article is to provide a nuts and bolts procedure for calculating scale factors used for reconstructing images directly in SNR units. The procedure includes scaling for noise equivalent bandwidth of digital receivers, FFTs and associated window functions (raw data filters), and array combining. Magn Reson Med, 2005. Published 2005 Wiley‐Liss, Inc.