bluuebunny/crossref_metadata_2025 huggingface dataset:
Lateral preferences in children with intellectual deficiency of idiopathic origin
Authors: Leconte Pascale , Fagard Jacqueline
Published: August 2006

The goal of this study was to evaluate lateral preferences in a population of children with intellectual deficiency of idiopathic origin, compared with those of typically developing (TD) children. Two groups of children with mild or moderate intellectual deficiency were observed. Handedness (using a 10‐item test and Bishop's card‐reaching task), eyedness and footedness were studied. The younger group consisted of sixteen 10‐ to 11‐year olds; the older group comprised fourteen 12‐ to 14‐year olds. A control group of fifteen TD children was matched for age with the younger group of intellectually deficient (ID) children. The results show that the occurrence of left‐handedness is not higher in children with ID of unknown origin than in age‐matched TD children. However, we observed a marginally reduced tendency toward right‐handedness in ID than in TD children: more mixed‐handers among ID than TD children; test‐retest consistency of hand preference significantly lower in the 10‐ to 11‐year‐old ID children than in the age‐matched TD children; greater tendency of ID children to use their nonpreferred left hand when the card was presented to the left, as compared with TD children. Left‐eyedness and crossed hand‐eye preference were also more frequent in ID than in age‐matched TD children. No age‐related difference in laterality was found in ID children. These results partially support other studies indicating that less rightward asymmetry is associated with intellectual deficiency in children. © 2006 Wiley Periodicals, Inc. Dev Psychobiol 48: 492–500, 2006.
Product Diversity in the Reaction of [(norbornadiene){CpP(iPr)2}Rh] with Alkyl Iodides
Authors: Ortega Esteban , Kleigrewe Nina , Kehr Gerald , Erker Gerhard , Fröhlich Roland
Published: August 2006

The reagents [(CpPR2)Li] [R = iPr (2b), cyclohexyl (2c)] react with [(nbd)RhCl] (nbd = norbornadiene) dimer [(1a)2] to yield the respective mononuclear complexes [(nbd)Rh(CpPR2)] (3b,c). Subsequent treatment of 3b with a large excess of MeI led to the formation of the stable organometallic phosphonium salt [(nbd)Rh{CpP(iPr)2Me}]I (4b). The analogous reaction of 3b with the slightly more bulky EtI or nPrI resulted in the formation of the dinuclear [μ‐CpP(iPr)2]‐bridged dirhodium complex [(nbd)Rh{CpP(iPr)2}Rh(nbd)I] (5b) and the corresponding ylides C5H4P(iPr)2R1 [R1 = Et (6b), nPr (6c)]. The rhodium complexes 3b, 4a and 5b were characterised by X‐ray crystal‐structure analyses. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Benzannulated Cyclooctanol Derivatives by Samarium Diiodide Induced Intramolecular Carbonyl–Alkene Coupling – Scope, Limitations, Stereoselectivity
Authors: Reißig Hans‐Ulrich , Khan Faiz Ahmed , Czerwonka Regina , Dinesh Chimmanamada U. , Shaikh Aarif L. , Zimmer Reinhold
Published: August 2006

A series of γ‐oxo esters 27–34 was prepared from methyl 2‐silyloxycyclopropanecarboxylates 1–9 as key building blocks in a flexible modular synthesis. Their samarium diiodide promoted cyclization to benzannulated cyclooctanol derivatives was systematically investigated. Samarium ketyl compounds derived from aldehydes 27 and 28 mainly provided tricyclic γ‐lactones 38 and 39 as a result of a cis‐selective ring‐closure process, whilst the related ketones 29–31 underwent trans‐selective reductive cyclization to furnish the expected benzannulated cyclooctanol derivatives 43–45 in moderate to excellent yields. With cyclohexanones 33 and 34 an interesting stereochemical matched/mismatched situation was observed. Whereas diastereomers 33a and 34a smoothly afforded tricyclic products 47 and 48 in good yields, compound 33b with apparently mismatched configuration did not undergo the samarium diiodide promoted ring‐closure process. An explanation for this intriguing behaviour is presented, together with an explanation for the cis/trans selectivity. Tricyclic γ‐lactone 38 could be smoothly deprotonated at one bridgehead and the generated lithium enolate was trapped with suitable alkyl halides. Remarkably, a clean α‐hydroxylation of 38 and 39 by direct employment of molecular oxygen was possible, providing high yields of the corresponding tertiary alcohols 54 and 55. These results demonstrate that the cyclization products prepared can easily be converted into higher functionalized benzannulated cyclooctane derivatives.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Photochemical Electron‐Transfer Generation of Arylthiirane Radical Cations with Tetranitromethane and Chloranil — Some Novel Observations
Authors: Puiatti Marcelo , Argüello Juan E. , Peñéñory Alicia B.
Published: August 2006

The radical cations from 2,2,3,3‐tetraphenylthiirane (1a), 2,2‐bis(4‐methoxyphenyl)‐3,3‐diphenylthiirane (1b), and trans‐2,3‐diphenylthiirane (1c) have been generated by photoinduced electron transfer (PET) reactions with tetranitromethane [C(NO2)4] and chloranil (CA). A charge‐transfer complexe (CTC) absorption is observed by UV/Vis spectroscopy between thiiranes (1) and C(NO2)4. On the other hand, quenching studies with azulene suggest that the ET reaction occurs between thiiranes and the triplet CA (3CA). The photochemical reaction of the CTC between thiiranes 1 and C(NO2)4 yields mainly the corresponding alkenes from the fragmentation of the radical‐cation intermediate 1·+, together with the products derived from nitration on the phenyl rings. However, oxygen transfer to afford the sulfoxides is not found. A marked solvent effect is observed in this reaction, with cage coupling favored in CH2Cl2 (nitration derivatives as primary products) and non‐cage coupling observed in CH3CN (the alkene as the primary product). The PET reactions between 1a–b and CA, in the presence of CH3OH (or another possible oxygen‐centered nucleophile), give the ketone derivatives through ring opening, followed by oxidative cleavage. Conversely, under the same experimental conditions, the thiirane 1c affords only trans‐stilbene 2c. This different behavior is ascribed to a different spin density in the corresponding singly occupied molecular orbital (SOMO) of the radical cation. For 1c+·, the spin density is concentrated at the sulfur atom, whereas for 1a·+ and 1b·+, the charge is distributed onto the aromatic rings. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
RhCl(PPh3)3/DPPF: A Useful and Efficient Catalyst for Cross‐Coupling Reactions of Activated Alkenyl Tosylates with Arylboronic Acids
Authors: Wu Jie , Zhang Liang , Gao Ke
Published: August 2006

A useful and effective rhodium catalyst system – [RhCl(PPh3)3/DPPF] – for the Suzuki–Miyaura cross‐coupling of activated alkenyl tosylates is described. The results not only represent the first examples of the rhodium‐catalyzed Suzuki–Miyaura coupling of activated alkenyl tosylates with arylboronic acids under mild conditions, but also provide an efficient route for the synthesis of some natural product‐like compounds, such as furan‐2(5H)‐one, coumarin, pyrone, and quinolin‐2(1H)‐one derivatives.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Asymmetric Synthesis of Arylpropionic Acids and Aryloxy Acids by Using Lactamides as Chiral Auxiliaries
Authors: Ammazzalorso Alessandra , Amoroso Rosa , Bettoni Giancarlo , De Filippis Barbara , Fantacuzzi Marialuigia , Giampietro Letizia , Maccallini Cristina , Tricca Maria L.
Published: August 2006

Two different dynamic kinetic resolution methods have been applied for the asymmetric synthesis of pharmaceutical arylpropionic acids and aryloxy acids by using amides of (S)‐lactic acid as chiral auxiliaries. For arylpropionic acids the esterification mediated by dicyclohexylcarbodiimide (DCC) and 4‐(dimethylamino)pyridine (DMAP) proceeds with good asymmetric induction, while for aryloxyacetic acids the key‐step is a diastereoselective substitution reaction in the presence of triethylamine and n‐hexylammonium iodide as additives. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Ammoxidation of straw‐pulp alkaline lignin by hydrogen peroxide
Authors: Qi‐Pei Jiang , Xiao‐Yong Zhang , Hai‐Tao Mo , Zuo‐Hu Li
Published: August 2006

A novel method that used hydrogen peroxide as an oxidizer to ammoxidize straw‐pulp alkaline lignin was studied. The purpose of this research was to find a more efficient way to utilize technical lignin, which is a major pollutant in China. The ammoxidation process was employed to nitrogen‐modify straw‐pulp lignin using ammonia liquor and hydrogen peroxide. At the desirable conditions, such as 120°C, 90 min reaction time, 20% hydrogen peroxide charge, and 20% ammonia charge, the nitrogen content of the ammoxidized product reached 11.62% and the ammonia nitrogen was 4.12%. The study showed that hydrogen peroxide could completely substitute for oxygen as an oxidizer for ammoxidizing alkaline lignin. Straw‐pulp alkaline lignin can be effectively converted into slow‐release fertilizer. © 2006 American Institute of Chemical Engineers Environ Prog, 2006
Performance of Alternative Oxide Anodes for the Electrochemical Oxidation of Hydrogen and Methane in Solid Oxide Fuel Cells
Authors: Tu H. , Apfel H. , Stimming U.
Published: August 2006

The electrode performances of the alternative oxides: La0.05Ca0.95Cr0.05Ti0.95O3‐δ‐8YSZ and Ce0.8TM0.2O2‐δ(TM=Mn, Co) for the direct electrochemical oxidation of methane are investigated to assess their potential as anode materials for efficient methane conversion in a SOFC. The electrochemical oxidation of hydrogen was also studied, for comparison. The oxides are characterised electrochemically with impedance spectroscopy in the frequency range from 10 mHz to 1MHz, using a three‐electrode geometry. They are compared to a standard Ni/8YSZ anode for the electrochemical oxidation of hydrogen. It is found that La0.05Ca0.95Cr0.05Ti0.95O3‐δ‐8YSZ demonstrates a poor electrochemical activity in both hydrogen and methane. However, the electrochemical activity of Ce0.8Mn0.2O2‐δ is promising, but the electronic conductivity needs to be increased, e.g., by adding a conducting oxide, before it can be used as an anode material in a SOFC.
Methanol Oxidation on Carbon Supported Pt and Ru – Modified Pt Nanoparticles: a Comparison with Single Crystal and Polycrystalline Electrodes
Authors: Lanova B. , Wang H. , Baltruschat H.
Published: August 2006

The rate of methanol adsorption and oxidation on carbon supported Pt nanoparticles and polycrystalline Pt has been studied by differential electrochemical mass spectrometry (DEMS) under continuous flow. At room temperature, the maximum adsorption rate at polycrystalline Pt is about 0.06 monolayer per second, whereas at Pt nanoparticles it is 0.04 monolayer per second. On polycrystalline Pt it amounts to 56% of a full CO monolayer, obtained by adsorbing CO from a CO saturated electrolyte. On the nanoparticles only 28% of a full CO monolayer can be obtained. The oxidation rate of the adsorbate is of zero order at polycrystalline Pt, whereas at nanoparticles it is of first order with respect to the coverage. Oxidation of methanol starts below the onset of CO2 formation. At polycrystalline Pt and Pt(111), the rate of CO2 formation is determined by the oxidation rate of the adsorbate. At Pt(332) and the nanoparticle electrodes, the rate of CO2 formation from bulk methanol is higher than that from methanol adsorbate, due to the heterogenity of these electrodes.

Similarly to Ru modified Pt single crystal electrodes, Ru modified polycrystalline Pt and Pt nanoparticles offer different adsorption sites for CO, which can be selectively populated.
Internal Reforming of Methane at Ni/YSZ and Ni/CGO SOFC Cermet Anodes
Authors: Timmermann H. , Fouquet D. , Weber A. , Ivers‐Tiffée E. , Hennings U. , Reimert R.
Published: August 2006

The internal reforming of methane on Ni/CGO and Ni/YSZ anodes was investigated with single cells operated at steam to carbon ratios from 0 to 3 and at temperatures of 800 °C and 950 °C. The incorporation of gas extraction ports allowed the measurement of the local gas composition in the anode gas compartment by gas chromatography. The methane conversion is presented as a function of feed gas composition, temperature, gas flow velocity, and electrical load. The impact of the anode material on the reforming reaction and on cell performance is shown. Methane conversion along the Ni/CGO anode was calculated with a one‐dimensional model; the required kinetic parameters were obtained by data fitting.
Binary Mixtures of Carbon Supported Pt and Ru Catalysts for PEM Fuel Cells
Authors: Mazurek M. , Benker N. , Roth C. , Fuess H.
Published: August 2006

Commercially available carbon‐supported pure Pt and pure Ru catalysts were heat treated in order to modify their individual particle sizes, mixed in a mortar and tested for their suitability as anode catalysts in polymer electrolyte fuel cells (PEMFCs). The procedure chosen for mixing monometallic catalysts should bring more flexibility to the preparation of catalysts, which could thus be easily adjusted to the working conditions. The catalyst mixtures were structurally characterized using a combination of X‐ray diffraction (XRD) and transmission electron microscopy (TEM), and indicated an increase in particle size with heat treatment temperature, while the size distribution remained sufficiently narrow. The particle size effect on the resulting activity of the catalyst mixtures was investigated by current‐voltage measurements (U/i curves) in single cell fuel cells. A mixture of the as‐received platinum and ruthenium gave the best results, which was almost comparable to a commercial Pt‐Ru alloy catalyst purchased from E‐TEK inc. Only a minor decrease in cell performance was seen during long term operation. Following operation, the X‐ray diffraction patterns show reflections of the Pt fcc phase, but not the hcp Ru phase. This may be explained by leaching of the pure ruthenium catalysts and re‐decoration on Pt nanoparticles, or by formation of an amorphous Ru oxide or, less likely, Pt‐Ru alloy during operation. However, these structural changes do not seem to significantly affect the cell performance.
Temperature Dependence of the Oxygen Reduction Kinetics on RuxSey/C Catalysts
Authors: Leveratto D. , Racz A. , Savinova E. R. , Stimming U.
Published: August 2006

The temperature dependence of the oxygen reduction kinetics on carbon‐supported RuxSey catalysts is studied using a rotating disc electrode in 0.5 M H2SO4 in the temperature interval from 25 °C to 65 °C. When the absolute value of the overpotential is below ca. 0.65 V, the reaction is limited by a one‐electron charge transfer step, where the transfer coefficient is independent of the temperature and equal to 0.44. The apparent activation enthalpy at zero overpotential is 0.49 eV and the pre‐exponential factor is independent of the temperature.
In situ fluorescence imaging of glutamate‐evoked mitochondrial Na+ responses in astrocytes
Authors: Bernardinelli Yann , Azarias Guillaume , Chatton Jean‐Yves
Published: August 2006

Astrocytes can experience large intracellular Na+ changes following the activation of the Na+‐coupled glutamate transport. The present study investigated whether cytosolic Na+ changes are transmitted to mitochondria, which could therefore influence their function and contribute to the overall intracellular Na+ regulation. Mitochondrial Na+ (Na) changes were monitored using the Na+‐sensitive fluorescent probe CoroNa Red (CR) in intact primary cortical astrocytes, as opposed to the classical isolated mitochondria preparation. The mitochondrial localization and Na+ sensitivity of the dye were first verified and indicated that it can be safely used as a selective Na indicator. We found by simultaneously monitoring cytosolic and mitochondrial Na+ using sodium‐binding benzofuran isophthalate and CR, respectively, that glutamate‐evoked cytosolic Na+ elevations are transmitted to mitochondria. The resting Na concentration was estimated at 19.0 ± 0.8 mM, reaching 30.1 ± 1.2 mM during 200 μM glutamate application. Blockers of conductances potentially mediating Na+ entry (calcium uniporter, monovalent cation conductances, K+ATP channels) were not able to prevent the Na response to glutamate. However, Ca2+ and its exchange with Na+ appear to play an important role in mediating mitochondrial Na+ entry as chelating intracellular Ca2+ with BAPTA or inhibiting Na+/Ca2+ exchanger with CGP‐37157 diminished the Na response. Moreover, intracellular Ca2+ increase achieved by photoactivation of caged Ca2+ also induced a Na elevation. Inhibition of mitochondrial Na/H antiporter using ethylisopropyl‐amiloride caused a steady increase in Na without increasing cytosolic Na+, indicating that Na+ extrusion from mitochondria is mediated by these exchangers. Thus, mitochondria in intact astrocytes are equipped to efficiently sense cellular Na+ signals and to dynamically regulate their Na+ content. © 2006 Wiley‐Liss, Inc.
Invariant mantling of growth cones by Schwann cell precursors characterize growing peripheral nerve fronts
Authors: Wanner Ina B. , Mahoney James , Jessen Kristján R. , Wood Patrick M. , Bates Margaret , Bunge Mary Bartlett
Published: August 2006

Little is known about the cytoarchitecture of growth fronts in developing mammalian nerves. We report here the first quantitative, ultrastructural analysis of growth cones (GCs) and their immediate cellular and tissue environment at tips of growing nerves that are nearing their targets in fore limbs of E14 rat embryos. Schwann cell precursor (SCP) marker, p75 neurotrophin receptor, and growth cone marker, SCG10, were used to identify nerve fronts, respectively. Using confocal 3D reconstructions and immunoelectron microscopy, we found that growth cone and Schwann cell precursor migrate together at the nerve front, where growth cone contact adjacent growth cone and Schwann cell precursor with similar frequency. Schwann cell precursor are extensively connected by adherens junctions and form elaborate scaffolds that enmantle growth cone at nerve fronts, so that 80% of the nerve front surface is covered by Schwann cell precursor. Although they interdigitate in complex ways among growth cone, the total contact area between growth cone and glial membranes is remarkably constant among the 100 growth fronts analyzed. In contrast to this consistency, other growth cone contacts varied markedly from front to front such that the frequencies of GC–GC contacts are increasing proportional to their decreasing contacts with mesenchymal tissue. Thus, at the nerve front, it is the Schwann cell precursor that are most exposed to extracellular environment while forming a surprisingly invariant substrate for advancing growth cone. This study shows for the first time that Schwann cell precursor are close and consistent cellular companions of growth cone in their approach to their final targets in the developing limb and suggests a previously unappreciated role for Schwann cell precursor in growth cone advance through the limb mesenchyme. © 2006 Wiley‐Liss, Inc.
GFAP‐expressing cells in the postnatal subventricular zone display a unique glial phenotype intermediate between radial glia and astrocytes
Authors: Liu Xiuxin , Bolteus Anna J. , Balkin Daniel M. , Henschel Oliver , Bordey Angélique
Published: August 2006

Neural stem cells in the adult subventricular zone (SVZ) derive from radial glia and express the astroglial marker glial fibrillary acidic protein (GFAP). Thus, they have been termed astrocytes. However, it remains unknown whether these GFAP‐expressing cells express the functional features common to astrocytes. Using immunostaining and patch clamp recordings in acute slices from transgenic mice expressing green fluorescent protein (GFP) driven by the promoter of human GFAP, we show that GFAP‐expressing cells in the postnatal SVZ display typical glial properties shared by astrocytes and prenatal radial glia such as lack of action potentials, hyperpolarized resting potentials, gap junction coupling, connexin 43 expression, hemichannels, a passive current profile, and functional glutamate transporters. GFAP‐expressing cells express both GLAST and GLT‐1 glutamate transporters but lack AMPA‐type glutamate receptors as reported for dye‐coupled astrocytes. However, they lack 100 μM Ba2+‐sensitive inwardly rectifying K+(KIR) currents expressed by astrocytes, but display delayed rectifying K+currents and 1 mM Ba2+‐sensitive K+currents. These currents contribute to K+transport at rest and maintain hyperpolarized resting potentials. GFAP‐expressing cells stained positive for both KIR2.1 and KIR4.1 channels, two major KIRchannels in astrocytes. Ependymal cells, which also derive from radial glia and express GFAP, display typical glial properties and KIRcurrents consistent with their postmitotic nature. Our results suggest that GFAP‐expressing cells in concert with ependymal cells can perform typical astrocytic functions such as K+and glutamate buffering in the postnatal SVZ but display a unique set of functional characteristics intermediate between astrocytes and radial glia. © 2006 Wiley‐Liss, Inc.
Behavior of in vitro cultured ameboid microglial cells migrating on Müller cell end‐feet in the quail embryo retina
Authors: Tassi Mohamed , Calvente Ruth , Marín‐Teva José L. , Cuadros Miguel A. , Santos Ana M. , Carrasco Maria‐Carmen , Sánchez‐López Ana M. , Navascués Julio
Published: August 2006

Ameboid microglial cells migrate tangentially on the vitreal part of quail embryo retinas by crawling on Müller cell end‐feet (MCEF) to which they adhere. These microglial cells can be cultured immediately after dissection of the eye and isolation of sheets containing the inner limiting membrane (ILM) covered by a carpet of MCEF (ILM/MCEF sheets), to which the cells remain adhered. Morphological changes of microglial cells cultured on ILM/MCEF sheets for 4 days were characterized in this study. During the first minutes in vitro, lamellipodia‐bearing bipolar microglial cells became rounded in shape. From 1 to 24 h in vitro (hiv), microglial cells swept and phagocytosed the MCEF on which they were initially adhered, becoming directly adhered on the ILM. MCEF sweep was dependent on active cell motility, as shown by inhibition of sweep after cytochalasin D treatment. From 24 hiv on, after MCEF phagocytosis, microglial cells became more flattened, increasing the surface area of their adhesion to substrate, and expressed the β1 subunit of integrins on their membrane. Morphological evidence suggested that microglial cells migrated for short distances on ILM/MCEF sheets, leaving tracks produced by their strong adhesion to the substrate. The simplicity of the isolation method, the immediate availability of cultured microglial cells, and the presence of multiple functional processes (phagocytosis, migration, upregulation of surface molecules, etc.) make cultures of microglial cells on ILM/MCEF sheets a valuable model system for in vitro experimental investigation of microglial cell functions. © 2006 Wiley‐Liss, Inc.
Functional changes in astroglial cells in epilepsy
Authors: Binder Devin K. , Steinhäuser Christian
Published: August 2006

Epilepsy comprises a group of disorders characterized by the periodic occurrence of seizures, and pathologic specimens from patients with temporal lobe epilepsy demonstrate marked reactive gliosis. Since recent studies have implicated glial cells in novel physiological roles in the CNS, such as modulation of synaptic transmission, it is plausible that glial cells may have a functional role in the hyperexcitability characteristic of epilepsy. Indeed, alterations in distinct astrocyte membrane channels, receptors and transporters have all been associated with the epileptic state. This review integrates the current evidence regarding astroglial dysfunction in epilepsy and the potential underlying mechanisms of hyperexcitability. Functional understanding of the cellular and molecular alterations of astroglia‐dependent hyperexcitability will help to clarify the physiological role of astrocytes in neural function as well as lead to the identification of novel therapeutic targets. © 2006 Wiley‐Liss, Inc.
Enhanced Connexin 43 immunoreactivity in penumbral areas in the human brain following ischemia
Authors: Nakase Taizen , Yoshida Yasuji , Nagata Ken
Published: August 2006

Astrocytes support neurons not only physically but also chemically by secreting neurotrophic factors and energy substrates. Moreover, astrocytes establish a glial network and communicate through gap junctions in the brain. Connexin 43 (Cx43) is one of major component proteins in astrocytic gap junctions. Heterozygote Cx43 KO mice and astrocyte specific Cx43 KO mice exhibited amplified brain damage after ischemic insults, suggesting a neuroprotective role for astrocytic gap junctions. However, some reports mentioned unfavorable effects of gap junctions in neuronal support. Therefore, the role of astrocytic gap junctions under ischemic condition remains controversial. Since these studies have been performed using animal models, we investigated the Cx43 expression in human brain after stroke. Brain slice sections were prepared from pathological samples in our hospital. Embolic stroke brains sectioned because of the stroke were considered as acute ischemic models. Multiple infarction brains sectioned because of pneumonia or cancer were considered as chronic models. We observed the levels of Cx43 in both lesioned and intact areas, and compared them with acute and chronic models. As the results, astrocytes were strongly activated in penumbral lesions both of acute and chronic ischemic models. The Cx43 immunoreactivity was significantly amplified in the penumbra of chronic model compared to that of the acute model. Neurons were well preserved in chronic model compared to acute model. These findings suggested that the brain may generate neuronal protection by increasing the levels of Cx43 and amplifying the astrocytic gap junctional intercellular communication under hypoxic condition. © 2006 Wiley‐Liss, Inc.
Decomposition of health inequality by determinants and dimensions
Authors: Lauridsen JØrgen , Christiansen Terkel , Gundgaard Jens , Häkkinen Unto , Sintonen Harri
Published: August 2006

The study integrates two methodologies so that income‐related inequality in general health can be decomposed into contributions from socio‐demographic characteristics to each of the dimensions defining general health. It is found that these relative contributions vary substantially across dimensions. For policy purposes such information is valuable as it indicates at which population groups and at which aspects of health efforts to reduce inequalities in health should be targeted. Copyright © 2006 John Wiley & Sons, Ltd.
The effects of expanding patient choice of provider on waiting times: evidence from a policy experiment
Authors: Dawson Diane , Gravelle Hugh , Jacobs Rowena , Martin Stephen , Smith Peter C.
Published: August 2006

Long waiting times for inpatient treatment in the UK National Health Service have been a source of popular and political concern, and therefore a target for policy initiatives. In the London Patient Choice Project, patients at risk of breaching inpatient waiting time targets were offered the choice of an alternative hospital with a guaranteed shorter wait. This paper develops a simple theoretical model of the effect of greater patient choice on waiting times. It then uses a difference in difference econometric methodology to estimate the impact of the London choice project on ophthalmology waiting times. In line with the model predictions, the project led to shorter average waiting times in the London region and a convergence in waiting times amongst London hospitals. Copyright © 2006 John Wiley & Sons, Ltd.
Fast rate coding in hippocampal CA3 cell ensembles
Authors: Leutgeb Stefan , Leutgeb Jill K. , Moser Edvard I. , Moser May‐Britt
Published: August 2006

Environments with overlapping features are represented by distinct patterns of activity in the hippocampus, enabling information to be stored and retrieved with minimal interference. This orthogonalization of correlated inputs is thought to take place within the hippocampus itself. However, the orthogonalization process has been shown to take days to develop in CA1. This prolonged time course is in striking contrast to the fast encoding of behavioral memory by the hippocampus. To explore this apparent paradox, we asked whether orthogonalization depended on the type of remapping exhibited by the hippocampal network. We have previously distinguished two types of remapping, global remapping, which results in the activation of different assemblies of place fields, and rate remapping, which encodes differences between cue constellations by substantial changes in firing rate without a change in the place code. Global remapping has previously been shown to be expressed immediately at novel locations. Here we asked if rate remapping follows a slower time course. Ensemble activity was recorded simultaneously from CA3 and CA1 in rats exposed to two similar, novel environments. It was found that rate changes in response to novel sensory cue configurations can form immediately, just as during global remapping, in particular in CA3. The fast encoding of both spatial and nonspatial information in CA3 is consistent with a role for the autoassociative CA3 circuitry in the acquisition and expression of episodic memories. © 2006 Wiley‐Liss, Inc.
Dissociating the past from the present in the activity of place cells
Authors: de Hoz Livia , Wood Emma R.
Published: August 2006

It has been proposed that declarative memories can be dependent on both an episodic and a semantic memory system. While the semantic system deals with factual information devoid of reference to its acquisition, the episodic system, characterized by mental time travel, deals with the unique past experience in which an event took place. Episodic memory is characteristically hippocampus‐dependent. Place cells are recorded from the hippocampus of rodents and their firing reflects many of the key characteristics of episodic memory. For example, they encode information about “what” happens “where,” as well as temporal information. However, when these features are expressed during an animal's behavior, the neuronal activity could merely be categorizing the present situation and could therefore reflect semantic memory rather than episodic memory. We propose that mental time travel is the key feature of episodic memory and that it should take a form, in the awake animal, similar to the replay of behavioral patterns of activity that has been observed in hippocampus during sleep. Using tasks designed to evoke episodic memory, one should be able to see memory reactivation of behaviorally relevant sequences of activity in the awake animal while recording from hippocampus and other cortical structures. © 2006 Wiley‐Liss, Inc.
Water quality andCryptosporidiumdistribution in an upland water supply catchment, Cumbria, UK
Authors: Sturdee A. , Foster I. , Bodley‐Tickell A. T. , Archer A.
Published: August 2006

Four micro‐catchment (MC) areas were identified to represent the main terrain types of a remote, sparsely populated upland valley catchment of 18 km2in Cumbria, UK. These were improved land with good grazing (IB), steeply sloping land with rough grazing (SG), wet moorland with sparse grazing (WM) and enclosed woodland that excluded livestock and deer (EW). Each MC contained the origin of a small stream that flowed into Swindale Beck, the river draining the valley. The water quality during the 14‐month study, as judged by chemical and physical parameters, was excellent, but it could not be regarded as pristine because of the frequent presence ofCryptosporidiumoocysts arising from livestock and wild mammal faeces. Oocysts (0·2–5·6 l−1) detected by genus‐specific immunofluorescent antibody were found in 32% of 188 water samples tested: ranking order EW 44%, IB 34%, Beck 30%, SG and WM 26%. Similarly, oocysts were identified in 9·5% of 1730 faecal samples. Small wild mammals (28%), calves (15·7%) and lambs (8·1%) were the dominant sources, whereas adult livestock (1·8%) and large wild mammals (4·8%) were less important. Autumn showed the highest occurrence of oocysts for both water and faecal samples. No hydrological controls were found to have a significant impact on the occurrence or concentration of oocysts in the main river or in the MCs, suggesting that their presence is controlled by seasonal changes in pathogen prevalence in the animal reservoir. Copyright © 2006 John Wiley & Sons, Ltd.
Hydrological importance of an unusual hazard in a mountainous basin: flood and landslide
Authors: Haritashya Umesh K. , Singh Pratap , Kumar Naresh , Singh Yatveer
Published: August 2006

The Bhagirathi River, a proglacial melt water stream of the Gangotri Glacier, is the principal source of the Ganges river system. The upper part of the basin lies in the high altitude region of the Garhwal Himalayas and is extensively covered by glaciers. We provide hydro‐meteorological insight into a severe storm that produced unusual high rains in June 2000 in the uppermost part of the Bhagirathi River. This storm was concentrated upstream of Gangotri town and triggered landslides/rockslides at several locations between the glacier snout and Gangotri town. One of the major rockslides blocked the Bhagirathi River at Bhujbas, about 3 km downstream of the Gangotri Glacier snout, creating an artificial lake at this location. High stream flow in the river, generated by rapid runoff response from mountain slopes along with melt runoff from the glacier, quickly increased the level of water stored in the artificial lake. Daily rainfall in this region rarely exceeds 10 mm, while total rainfall during this 6‐day storm was 131·5 mm. This unusual rain event occurred during the tourist season in June, consequently trapping a large number of tourists and vendors in this area. Sudden release of stored water generated floods that created havoc downstream of the artificially created lake. This paper presents the hydrological and meteorological information related to such an unusual and devastating event observed in the high altitude region of the Himalayas. Copyright © 2006 John Wiley & Sons, Ltd.
In vivobiostability of shore 55D polyether polyurethanes with and without fluoropolymer surface modifying endgroups
Authors: Ward Robert , Anderson James , McVenes Rick , Stokes Ken
Published: August 2006

Polyether polyurethanes are subject to autooxidation and environmental stress cracking (ESC) because of interactions with lysosomal oxygen‐free radicals. Oxidation can also be catalyzed by and caused by direct (redox) reaction with transition metal ions (metal ion oxidation, MIO). The source of the ions is corrosion of metallic parts within an implanted device. A previous study on a Shore 80A polyether polyurethane modified with fluoropolymer surface modifying end groups demonstrated improved biostability over unmodified controls. We predicted that this could be extrapolated to the inherently more biostable Shore 55D version (E55DF). While it is difficult to demonstrate significant biodegradation in the harder polymers within a reasonable time frame, we did see excellent biologic autooxidation and ESC resistance for both E55DF and its unmodified Shore 55D (P55D) control. E55DF was slightly, but significantly more resistant to MIO than P55D. This was particularly evident in molecular weight distributions with P55D exhibiting a large decrease in number average molecular weight compared to no change for E55DF. Both were markedly superior to the softer Shore 80A control. It does appear that one can extrapolate acceleratedin vivobiostability results with the softer polymers to their harder analogues. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
In vivo biostability of polyether polyurethanes with fluoropolymer surface modifying endgroups: Resistance to biologic oxidation and stress cracking
Authors: Ward Bob , Anderson James , McVenes Rick , Stokes Ken
Published: August 2006

A series of Shore 80A polyether polyurethanes were synthesized with from 0 to 6% fluoropolymer surface modifying endgroups (SME) to provide the bulk properties of the polyurethane with the surface properties of the fluoropolymer. It was theorized that the fluoropolymer would migrate to the surface, forming a monolayer barrier to the oxidants and crack‐driving agents released by macrophages and foreign body giant cells in vivo. In a 12‐week biostability screening test, samples strained to 400% elongation appeared to be highly stable. In a longer‐term study, the fluoropolymer SME significantly delayed, but did not completely prevent the onset of microcracking and the development of environmental stress cracking in strained samples. Even so, the 4 and 6% SME polymers explanted at 2 years performed significantly better than the control. FTIR analysis did not correlate with SME concentration, but increased hydrogen‐bonding index and loss of aliphatic ether (autoxidation) did correlate with the visual appearance and density of microcracks. Significant molecular weight reductions were seen for the SME‐free control, but were small (within instrumental error) for the polymers with SME. The use of fluoropolymer as a SME does appear to be warranted as a means to improve polyether polyurethane biostability. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Osteoprecursor cell response to strontium‐containing hydroxyapatite ceramics
Authors: Xue Weichang , Moore Jessica L. , Hosick Howard L. , Bose Susmita , Bandyopadhyay Amit , Lu W.W. , Cheung Kenneth M.C. , Luk Keith D.K.
Published: August 2006

The objective of this study was to investigate the in vitro bioactivity of strontium‐containing hydroxyapatite (Sr‐HA), and its effect on cellular attachment, proliferation, and differentiation. The effect of Sr‐HA has been compared with that of hydroxyapatite (HA), which is widely used in orthopedics and dentistry. Sr‐HA ceramic containing 10 mol % was prepared. The bioactivity of Sr‐HA was evaluated in vitro by immersion in simulated body fluid (SBF). After immersion in SBF, Sr‐HA exhibited greater ability to induce apatite precipitation on its surface than did HA. The possible effects on cell behavior of Sr‐HA were examined by culturing osteoprecursor cells (OPC1) on materials surfaces. Cell shape and cell‐material interactions were analyzed by scanning electron microscope (SEM) and the MTT assay was used to determine cell proliferation on samples. When compared with HA, Sr‐HA promoted better OPC1 cell attachment and proliferation, and showed no deleterious effects on extracellular matrix formation and mineralization. Confocal scanning microscopy was used to assess the expression of specific osteoblast proteins: alkaline phosphatase (ALP) and osteopontin (OPN). The results obtained indicate that the presence of Sr stimulates OPC1 cell differentiation, and enhances ALP and OPN expression. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
In vitro differentiation of hepatic progenitor cells from mouse embryonic stem cells induced by sodium butyrate
Authors: Zhou Qing‐Jun , Xiang Li‐Xin , Shao Jian‐Zhong , Hu Ruo‐Zhen , Lu Yong‐Liang , Yao Hang , Dai Li‐Cheng
Published: August 2006

Recently it was shown that embryonic stem (ES) cells could differentiate into hepatocytes both in vitro and in vivo, however, prospective hepatic progenitor cells have not yet been isolated and characterized from ES cells. Here we presented a novel 4‐step procedure for the differentiation of mouse ES cells into hepatic progenitor cells and then hepatocytes. The differentiated hepatocytes were identified by morphological, biochemical, and functional analyses. The hepatic progenitor cells were isolated from the cultures after the withdrawal of sodium butyrate, which was characterized by scant cytoplasm, ovoid nuclei, the ability of rapid proliferation, expression of a series of hepatic progenitor cell markers, and the potential of differentiation into hepatocytes and bile duct‐like cells under the proper conditions that favor hepatocyte and bile epithelial differentiation. The differentiation of hepatocytes from hepatic progenitor cells was characterized by a number of hepatic cell markers including albumin secretion, upregulated transcription of glucose‐6‐phophatase and tyrosine aminotransferase, and functional phenotypes such as glycogen storage. The results from our experiments demonstrated that ES cells could differentiate into a novel bipotential hepatic progenitor cell and mature into hepatocytes with typical morphological, phenotypic and functional characteristics, which provides an useful model for the studies of key events during early liver development and a potential source of transplantable cells for cell‐replacement therapies. J. Cell. Biochem. 100: 29–42, 2007. © 2006 Wiley‐Liss, Inc.
Chondrocyte apoptosis is not essential for cartilage calcification: Evidence from an in vitro avian model
Authors: Pourmand Eric P. , Binderman Itzhak , Doty Stephen B. , Kudryashov Valery , Boskey Adele L.
Published: August 2006

The calcification of cartilage is an essential step in the process of normal bone growth through endochondral ossification. Chondrocyte apoptosis is generally observed prior to the transition of calcified cartilage to bone. There are, however, contradictory reports in the literature as to whether chondrocyte apoptosis is a precursor to cartilage calcification, a co‐event, or occurs after calcification. The purpose of this study was to test the hypothesis that chondrocyte apoptosis is not a requirement for initial calcification using a cell culture system that mimics endochondral ossification. Mesenchymal stem cells harvested from Stages 21–23 chick limb buds were plated as micro‐mass cultures in the presence of 4 mM inorganic phosphate (mineralizing conditions). The cultures were treated with either an apoptosis inhibitor or stimulator and compared to un‐treated controls before the start of calcification on day 7. Inhibition of apoptosis with the caspase inhibitor Z‐Val‐Ala‐Asp (O‐Me)‐fluoromethylketone (Z‐VAD‐fmk) caused no decreases in calcification as indicated by radioactive calcium uptake or Fourier transform infrared (FT‐IR) analysis of mineral properties. When apoptosis was inhibited, the cultures showed more robust histological features (including more intense staining for proteoglycans, and more intact cells within the nodules as well as along the periphery of the cells as compared to untreated controls), more proliferation as noted by bromo‐deoxyuridine (BrdU) labeling, decreases in terminal deoxynucleotidyl transferase (Tdt)‐mediated dUTP nick‐end labeling (TUNEL) staining, and fewer apoptotic bodies in electron microscopy. Stimulation of apoptosis with 40–120 nM staurosporine prior to the onset of calcification resulted in inhibition of calcium accretion, with the extent of total calcium uptake significantly decreased, the amount of matrix deposition impaired, and the formation of abnormal mineral crystals. These results indicate that chondrocyte apoptosis is not a pre‐requisite for calcification in this culture system. J. Cell. Biochem. 100: 43–57, 2007. © 2006 Wiley‐Liss, Inc.
Insulin‐like growth factors induce apoptosis as well as proliferation in LIM 1215 colon cancer cells
Authors: Fu Ping , Thompson Julian A. , Leeding Kerri S. , Bach Leon A.
Published: August 2006

The insulin‐like growth factor (IGF) system plays an important role in cell proliferation and survival. However, more recently, a small number of studies have shown that IGFs induce apoptosis in some cells. Our initial studies showed this occurred in LIM 1215 colon cancer cells but not RD rhabdomyosarcoma cells. IGFs induced both proliferation and apoptosis in LIM 1215 cells, and the induction of apoptosis was dose‐dependent. [R54, R55]IGF‐II, which binds to the IGF‐I receptor with normal affinity but does not bind to the IGF‐II receptor, induced apoptosis to the same extent as IGF‐II, whereas [L27]IGF‐II, which binds to the IGF‐I receptor with 1000‐fold reduced affinity, had no effect on apoptosis. These results suggest that the IGF‐I receptor is involved in induction of apoptosis. Western blot analyses demonstrated that Akt and Erk1/2 were constitutively activated in RD cells. In contrast, phosphorylation of Akt and Erk1/2 were transient and basal expression of Akt protein was lower in LIM 1215 cells. Analysis of apoptosis‐related proteins showed that IGFs decreased pro‐caspase‐3 levels and increased expression of pro‐apoptotic Bad in LIM 1215 cells. IGFs co‐activate proliferative and apoptotic pathways in LIM 1215 cells, which may contribute to increased cell turnover. Since high turnover correlates with poor prognosis in colorectal cancer, this study provides further evidence for the role of the IGF system in its progression. J. Cell. Biochem. 100: 58–68, 2007. © 2006 Wiley‐Liss, Inc.
Nuclear localization of liver X receptor α and β is differentially regulated
Authors: Prüfer Kirsten , Boudreaux Jeanne
Published: August 2006

Activity of nuclear receptors is regulated by their nuclear localization. Liver X receptors (LXR) α and β are nuclear receptors that regulate transcription of genes for cholesterol metabolism, cholesterol transport, and lipogenesis. While LXR α and β are very similar in structure and exhibit similar ligand binding properties, their physiological roles are quite different. Since the LXRs fall into a class of receptors that move between the nucleus and cytoplasm, experiments were conducted to determine whether LXR α and LXR β show differences in their nuclear localization pattern. To determine the location of each receptor, cell lines stably expressing yellow fluorescent protein (YFP) chimeras with either LXR α or LXR β were examined. Retention in the nucleus of the chimeric proteins in the presence or absence of ligands was assessed using fluorescence microscopy coupled with digitonin permeabilization assays. Surprisingly, differences were found between LXR α and LXR β. Whereas unliganded LXR α was retained in the nucleus, unliganded LXR β was partially exported. Mutations were then introduced into putative nuclear localization sequences (NLS) to determine which sequences are important for nuclear localization and function. Mutation in one such sequence abolished nuclear localization of LXR α, whereas the analogous change in LXR β had a much less dramatic effect. Mutations in analogous putative NLS also differentially affected transcriptional activation by LXR α and LXR β. These data demonstrate for the first time that nuclear retention and localization as well as function of LXR α and LXR β are differentially regulated. J. Cell. Biochem. 100: 69–85, 2007. © 2006 Wiley‐Liss, Inc.