bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetic and Thermodynamic Studies of the Disproportionation of Hydrogen Peroxide by Dimanganese(ii,ii) and ‐(ii,iii) Complexes of a Bridging Phenolate Ligand
Authors: Dubois Lionel , Xiang Dao‐Feng , Tan Xiang‐Shi , Latour Jean‐Marc
Published: April 2005

The dimanganese(ii,ii) complexes [Mn2(L)(OAc)2(CH3OH)]‐(ClO4) (1a) and [Mn2(L)(OBz)2(H2O)](ClO4) (1b) as well as the dimanganese(ii,iii) complex [Mn2(L)(OAc)2(CH3OH)]‐(ClO4)2 (2a), where HL is the asymmetric phenol ligand2‐[bis(2‐pyridylmethyl)aminomethyl]‐6‐{[(benzyl)(2‐pyridyl‐methyl)amino]methyl}‐4‐methylphenol, react with hydrogen peroxide in acetonitrile solution. The initial reaction rates and their temperature and acid/base dependencies were investigated by monitoring the dioxygen evolution. These studies revealed a first‐order dependence on both the catalyst and H2O2 and a strong influence of the carboxylate. Electrospray ionisation mass spectrometry as well as EPR and UV/Vis spectroscopy were used to monitor the reaction catalysed by 2a. The same bis(μ‐oxo)dimanganese(III,IV) and (μ‐oxo)dimanganese(ii,iii) active species as found for 1a were detected in the catalytic medium. The EPR spectra recorded during the catalase‐like reaction revealed the accumulation of the magnetically uncoupled dimanganese(ii,iii) precursor of the active bis(μ‐oxo)dimanganese(III,IV) species which dominates the spectra in the case of 1a. This difference can be attributed to the different pH conditions generated by the reaction and reflects differences in the initiation phases for the two catalysts. Overall, the kinetic and thermodynamic studies of H2O2 disproportionation by these dimanganese complexes are fully consistent with the mechanism deduced from our previous extensive spectroscopic studies. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
CuI and CuII Complexes Containing Nitrite and Tridentate Aromatic Amine Ligand as Models for the Substrate‐Binding Type‐2 Cu Site of Nitrite Reductase
Authors: Yokoyama Hiroshi , Yamaguchi Kazuya , Sugimoto Manabu , Suzuki Shinnichiro
Published: April 2005

CuI and CuII complexes containing a tridentate aromatic amine compound [bis(6‐methyl‐2‐pyridylmethyl)amine, Me2bpa] in the absence and presence of nitrite have been prepared as models for the active site of dissimilatory copper‐containing nitrite reductase (CuNIR). [CuII(Me2bpa)(H2O)(ClO4)]ClO4 (1), [CuII(Me2bpa)(NO2)(ClO4)] (2), [CuI(Me2‐bpa)(CH3CN)]PF6 (3) and [CuI(Me2bpa)(NO2)]2·[(Ph3P)2‐NPF6] (4) were prepared. The X‐ray crystal structural analyses of 1, 2, and 4 reveal that the geometries of the Cu centers are distorted square pyramidal, distorted octahedral, and tetrahedral, respectively. The coordination modes of the nitrite ligands in 2 and 4 depend on the oxidation state of the copper ion: nitrite is coordinated to CuII and CuI through two oxygen atoms (O,O'‐coordination mode) and one nitrogen atom (N‐coordination mode), respectively. A comparison of the absorption spectra of 1 and 2 in acetone solution indicates that the 387‐nm absorption band (ϵ = 780 M–1 cm–1) of 2 is a charge‐transfer transition. The broad absorption band at around 320 nm (ϵ ≈ 5000 M–1 cm–1) of 4 in dichloromethane is also due to a charge‐transfer transition. Functional modeling of CuNIR has been accomplished by treating solutions of 4 with acid; the nitrite‐binding CuI complex quantitatively gives the one‐electron reduction product,NO. The nitrite reduction of 4 in dichloromethane obeys a second‐order rate law, suggesting that the rate‐determining step would be protonation of the nitrite ligand of 4. Electronic structure calculations of the CuI and CuII complexes containing Me2bpa and nitrite by the density functional theory method demonstrate that the net charge of nitrite in CuI(Me2bpa)(nitro) is larger than that in CuI(Me2bpa)(nitrito). The mechanism of the nitrite reduction is discussed in comparison with the enzyme reaction mechanism of CuNIR. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Two New Diphenoxo‐Bridged Discrete Dinuclear CuIIGdIII Compounds with Cyclic Diimino Moieties: Syntheses, Structures, and Magnetic Properties
Authors: Koner Rajesh , Lee Gene‐Hsiang , Wang Yu , Wei Ho‐Hsiang , Mohanta Sasankasekhar
Published: April 2005

Two Schiff base compartmental ligands, H2L1 and H2L2, derived from the condensation of 3‐ethoxysalicylaldehyde with 1,2‐diaminocyclohexane and orthophenylenediamine, respectively, have been utilized to isolate two diphenoxo‐bridged discrete dinuclear CuIIGdIII complexes, [CuII(H2O)L1GdIII(NO3)3] (3) and [CuIIL2GdIII(NO3)3] (4). This is the first report on the 3d‐4f compounds derived from compartmental Schiff base ligands with cyclic diamines. The compounds 3 and 4 crystallize in the triclinic P and orthorhombic Pna2(1) space groups, respectively, with the following unit cell parameters – 3: a = 8.8713(2) Å, b = 12.8399(3) Å, c = 14.0067(3) Å, α = 80.6649(5)°, β = 77.4059(5)°, γ = 76.8879(5)°, and Z = 2; 4: a = 9.2210(1) Å, b = 16.5407(2) Å, c = 19.9248(4) Å, and Z = 4. Structural analysis reveals that both are discrete dinuclear complexes. In 3, one water molecule is coordinated to the copper(II) ion to result in a square‐pyramidal coordination geometry, while the geometry of the coppe(II) center in 4 is square planar. In both complexes, the gadolinium(III) center has an O10 coordination environment. In contrast to expectation, although the N2O2 cavity affords a better planar environment for the copper(II) center in 4, the bridging moiety in complex 3 is more planar than that in 4 or in most of the previously reported examples (the dihedral angle between two CuO2Gd planes: 2.1° for 3 and 7.1° for 4). Variable‐temperature and variable‐field magnetic measurements reveal that the metal centers in both the complexes are ferromagnetically coupled (J values: 6.3 cm–1 for 3 and 5.4 cm–1 for 4; H = –2JSCu·SGd). Interestingly, complex 3 exhibits strongest ferromagnetic interaction among the related compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Synthesis of Palladium(II) and Platinum(II) Complexes with Crown Ether Phosphane Ligands: Stille Coupling of Aryl Iodides in Water
Authors: Fresneda Jorge , de Jesús Ernesto , Gómez‐Sal Pilar , López Mardomingo Carmen
Published: April 2005

The crown ether phosphanes PAr*Ph2(1) and PAr*2R [Ar* = 3,4‐(18‐crown‐6)‐phenyl; R = Me (2); R = Ph (3)], prepared from PCl2R and Ar*Li, have been studied. The syntheses and characterization of their oxides (4–6), and their BH3(7–9), PdCl2(10–12), and PtCl2(13–15) complexes are reported. The molecular structure of the borane complex PAr*2Ph·BH3(9) has been determined by X‐ray structural analysis. Spectroscopic data suggest that phosphanes1–3have similar electronic properties and steric requirements to the corresponding phenylphosphane ligands PPh2Me and PPh3. Crown ether methylphosphane2and its complexes are remarkably water soluble, but1and3are only slightly soluble. Palladium(II) complexes14and15have been tested as catalysts in the Stille coupling of phenyltrichlorostannanes and aryl iodides in water. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Dinuclear Copper(II) Complexes of Two Homologous Pyrazine‐Based Bis(terdentate) Diamide Ligands
Authors: Klingele (née Hausmann) Julia , Moubaraki Boujemaa , Murray Keith S. , Boas John F. , Brooker Sally
Published: April 2005

The 1:1 reactions of the new bis(terdentate) diamide ligandN,N'‐bis(2‐pyridylmethyl)pyrazine‐2,5‐dicarboxamide(H2L1) and its higher homologue N,N'‐bis[2‐(2‐pyridyl)ethyl]pyrazine‐2,5‐dicarboxamide (H2L2) with Cu(BF4)2·4 H2O in the absence of added base have consistently afforded dicopper(II) complexes of the doubly deprotonated ligands (L1)2– and (L2)2–. The complex [CuII2(L2)(H2O)2(MeCN)2](BF4)2 (2a) has been structurally characterised. Subsequently, reactions employing a correct stoichiometric 2:1 metal‐to‐ligand ratio in MeCN have afforded bulk samples of the dinuclear complexes. The compounds [CuII2(L1)(MeCN)2(H2O)2](BF4)2·H2O (1a·H2O) and [CuII2(L2)(H2O)4(BF4)2]·2 H2O (2b·2 H2O) have been structurally characterised. While complex 1a·H2O of the lower ligand homologue exhibits very weak antiferromagnetic spin coupling (J = –0.24 cm–1), complex 2b of the higher ligand homologue exhibits very weak ferromagnetic spin coupling (J = +0.67 cm–1). EPR studies have been carried out on polycrystalline powders and frozen DMF solutions of 1a·H2O and 2b·2 H2O. The EPR spectra of the polycrystalline powders indicate the presence of dipolar broadening and weak intermolecular exchange, while those of the frozen DMF solutions are characteristic of dipolar‐coupled CuII pairs within the dinuclear molecules, with no evidence of intra‐ or intermolecular exchange. The spectral simulations confirm that the binuclear structure and the Cu···Cu distances are retained in frozen solution. Dinuclear SiF62– containing compounds, [CuII2(L1)(H2O)4](SiF6) (1b) and {[CuII2(L1)(H2O)2(μ‐SiF6)]·4 H2O}∞ (1c·4 H2O), were obtained serendipitously, in nearly quantitative yield, by the 2:1 reaction of Cu(BF4)2·4 H2O with H2L1 in H2O. The unexpected SiF62– anions were generated in the course of the reaction by partial hydrolysis of the BF4– anions employed, thus forming traces of HF which reacted with the glassware. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
One‐Dimensional Chains Formed by First‐Row Transition Metal(II) Nitrates and Pyrimidine – Influence of Water Coordination on Structural Reliability
Authors: Barnett Sarah A. , Champness Neil R. , Wilson Claire
Published: April 2005

An isostructural family of one‐dimensional coordination polymers, [M(NO3)2(pym)(H2O)2]∞ [M = Mn (1), Co (2), Ni (3), Zn (4); pym = pyrimidine], has been prepared and their phase purity assessed. It is shown that in contrast to otherM(NO3)2–pyrimidine coordination polymers, 1–4 show a surprising preference for the structure reported herein rather the wide variety of other possible product architectures. It is also shown that a related complex [Ni(NO3)2(pym)(MeCN)2]∞ (5), in which water ligands observed in 1–4 are replaced by MeCN molecules, can also be prepared. However, 5 is highly hygroscopic and readily converts to 3 in the presence of atmospheric water. The implication of the uniformity of structure is discussed in relation to the serendipitous coordination of water molecules to the metal centres. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Use of spatial factors in the analysis of heavy metals in sediments in a Brazilian coastal region
Authors: Bailey T. C. , Barcellos C. , Krzanowski W. J.
Published: April 2005

Environmental phenomena often generate complex data which are not only multivariate, but where spatial structure and dependency may also be important. One potential area of interest is that of identifying combinations of variables which exhibit distinctive spatial structure in a set of multivariate and geographically indexed observations, e.g. long, as opposed to short, range spatial contiguity. Such components may serve not only to characterize the main determinants in the geographical distribution of a set of environmental measurements, but may also provide useful insight into the physical or environmental processes underlying and governing that distribution. This article suggests one form of multivariate technique which may be useful in such a context. We demonstrate the method in relation to data comprising measures of various heavy metals in sediments in a Brazilian coastal region. Copyright © 2005 John Wiley & Sons, Ltd.
Mapping sea bird densities over the North Sea: spatially aggregated estimates and temporal changes
Authors: Pebesma Edzer J. , Duin Richard N. M. , Burrough Peter A.
Published: April 2005

In the Dutch sector of the North Sea, sea bird densities are recorded bi‐monthly by using airborne strip‐transect monitoring. From these data we try to estimate: (i) high‐resolution spatial patterns of sea bird densities; (ii) low‐resolution spatial‐average bird densities for large areas; and (iii) temporal changes in (i) and (ii), using data on Fulmaris glacialis as an example. For spatial estimation, we combined Poisson regression for modelling the trend as a function of water depth and distance to coast with kriging interpolation of the residual variability, assuming spatial (co)variances to be proportional to the trend value. Spatial averages were estimated by block kriging. For estimating temporal differences we used residual cokriging for two consecutive years, and show how this can be extended to analyse trends over multiple years. Approximate standard errors are obtained for all estimates. A comparison with a residual simple kriging approach reveals that ignoring temporal cross‐correlations leads to a severe loss of statistical accuracy when assessing the significance of temporal changes.This article shows results for Fulmaris glacialis monitored during August/September in 1998 and 1999. Copyright © 2005 John Wiley & Sons, Ltd.
An improved formula obtained by simulated annealing for the computation of maximum SINR for DS‐CDMA receiver with exponentially weighted despreading function
Authors: Ciftlikli Cebrail , Kalinli Adem , Develi Ibrahim
Published: April 2005

It is well known that direct sequence‐code division multiple access (DS‐CDMA) receiver using exponentially weighted despreading function outperforms significantly receiver using rectangular despreading function. The maximum value of the signal‐to‐interference‐plus‐noise ratio (SINR) for this type of receiver is an important indicator to evaluate the bit error rate (BER) performance of the system. In this paper, we propose an improved formula obtained by using simulated annealing (SA) algorithm to calculate the maximum value of the SINR. It is shown that the results computed by the proposed formula are more accurate than the results obtained by the simplified formula available in the literature. Copyright © 2005 AEIT.
Assessment by M‐FISH of karyotypic complexity and cytogenetic evolution in bladder cancer in vitro
Authors: Williams Sarah V. , Adams Jacqui , Coulter Jane , Summersgill Brenda M. , Shipley Janet , Knowles Margaret A.
Published: April 2005

We carried out multiplex fluorescence in situ hybridization (M‐FISH) and follow‐up FISH studies on a large series of transitional cell carcinoma (TCC) cell lines and 2 normal urothelium–derived cell lines, several of which have not had karyotypes reported previously. M‐FISH analysis, with appropriate follow‐up, complements conventional cytogenetic analysis and array CGH studies, allowing a more accurate definition of karyotype. The detailed karyotypic data obtained will assist in choosing suitable cell lines for functional studies and identifies common losses, gains, breakpoints and potential fusion gene sites in TCC. We have shown changes in cell lines RT112 and DSH1 following prolonged culture, and differences in karyotype, between RT112 cultures obtained from different sources. We propose a model for the evolutionary changes leading to these differences. A comparison with the literature found other examples of differences in cell‐line karyotypes between different sources. Nevertheless, several karyotypic changes were preserved between different sources of the same cell line and were also seen in more than one cell line. These may be the most important changes and include −8p, +20, 4q−, 10p−, 16p− and breaks in 8p21. We carried out a more detailed follow‐up of some regions, which showed involvement of 8p breaks and losses in 15 of 16 TCC cell lines but in neither of the normal urothelium–derived cell lines. Some changes represented distal loss, whereas others were small deletions. Further study of this region is warranted. Supplementary material for this article can be found on the Genes, Chromosomes and Cancer website at http://www.interscience.wiley.com/jpages/1045‐2257/suppmat/index.html. © 2005 Wiley‐Liss, Inc.
Acute myeloid leukemia with a complex aberrant karyotype is a distinct biological entity characterized by genomic imbalances and a specific gene expression profile
Authors: Schoch Claudia , Kern Wolfgang , Kohlmann Alexander , Hiddemann Wolfgang , Schnittger Susanne , Haferlach Torsten
Published: April 2005

Acute myeloid leukemia (AML) with a complex aberrant karyotype is a distinct biological entity. It is characterized by: (1) a sharp increase in incidence above age 50; (2) a characteristic pattern of chromosomal gain and, especially, loss, that is, of 5q14q33, 7q32q35, and 17p13, translating into reduced expression of genes in these regions; (3) a unique gene expression pattern including up‐regulation of genes involved in DNA repair; (4) a high incidence of TP53 deletions and/or mutations; and (5) an overall unfavorable prognosis. Further unraveling the biology of AML with a complex aberrant karyotype by gene expression profiling may provide deeper insights into the pathogenesis of as well as the reasons for chemoresistance in this AML subtype. These data may be the basis for developing targeted therapeutic strategies to increase the cure rate in patients with AML and a complex aberrant karyotype. © 2005 Wiley‐Liss, Inc.
Failure and function of intracellular pH regulation in acute hypoxic‐ischemic injury of astrocytes
Authors: Chesler Mitchell
Published: April 2005

Astrocytes can die rapidly following ischemic and traumatic injury to the CNS. Brain acid–base status has featured prominently in theories of acute astrocyte injury. Failure of astrocyte pH regulation can lead to cell loss under conditions of severe acidosis. By contrast, the function of astrocyte pH regulatory mechanisms appears to be necessary for acute cell death following the simulation of transient ischemia and reperfusion. Severe lactic acidosis, and the failure of astrocytes to regulate intracellular pH (pHi) have been emphasized in brain ischemia under hyperglycemic conditions. Direct measurements of astrocyte pHi after cardiac arrest demonstrated a mean pHi of 5.3 in hyperglycemic rats. In addition, both in vivo and in vitro studies of astrocytes have shown similar pH levels to be cytotoxic. Whereas astrocytes exposed to hypoxia alone may require 12–24 h to die, acidosis has been found to exacerbate and speed hypoxic loss of these cells. Recently, astrocyte cultures were exposed to hypoxic, acidic media in which the large ionic perturbations characteristic of brain ischemia were simulated. Upon return to normal saline (“reperfusion”), the majority of cells died. This injury was dependent on external Ca2+ and was prevented by inhibition of reversed Na+‐Ca2+ exchange, blockade of Na+‐H+ exchange, or by low pH of the reperfusion saline. These data suggested that cytotoxic elevation of [Ca2+]i occurred during reperfusion due to a sequence of activated Na+‐H+ exchange, cytosolic Na+ loading, and resultant reversal of Na+‐Ca2+ exchange. The significance of this reperfusion model to ischemic astrocyte injury in vivo is discussed. © 2005 Wiley‐Liss, Inc.
Potassium homeostasis in the ischemic brain
Authors: Leis Jerome A. , Bekar Lane K. , Walz Wolfgang
Published: April 2005

Extracellular [K+] can range within 2.5–3.5 mM under normal conditions to 50–80 mM under ischemic and spreading depression events. Sustained exposure to elevated [K+]o has been shown to cause significant neuronal death even under conditions of abundant glucose supply. Astrocytes are well equipped to buffer this initial insult of elevated [K] through extensive gap junctional coupling, Na+/K+ pump activity (with associated glycogen and glycolytic potential), and endfoot siphoning capability. Their abundant energy availability and alkalinizing mechanisms help sustain Na+/K+ ATPase activity under ischemic conditions. Furthermore, passive K+ uptake mechanisms and water flux mediated through aquaporin‐4 channels in endfoot processes are important energy‐independent mechanisms. Unfortunately, as the length of ischemic episode is prolonged, these mechanisms increase to a point where they begin to have repercussions on other important cellular functions. Alkalinizing mechanisms induce an elevation of [Na+]i, increasing the energy demand of Na+/K+ ATPase and leading to eventual detrimental reversal of the Na+/glutamate− cotransporter and excitotoxic damage. Prolonged ischemia also results in cell swelling and activates volume regulatory processes that release excessive excitatory amino acids, further exacerbating excitotoxic injury. In the days following ischemic injury, reactive astrocytes demonstrate increased cell size and process thickness, leading to improved spatial buffering capacity in regions outside the lesion core where there is better neuronal survival. There is a substantial heterogeneity among reactive astrocytes, with some close to the lesion showing decreased buffering capacity. However, it appears that both Na+/K+ ATPase activity (along with energy production processes) as well as passive K+ uptake mechanisms are upregulated in gliotic tissue outside the lesion to enhance the above‐mentioned homeostatic mechanisms. © 2005 Wiley‐Liss, Inc.
Fibrin‐modifying serine proteases thrombin, tPA, and plasmin in ischemic stroke: A review
Authors: Sheehan John J. , Tsirka Stella E.
Published: April 2005

Ischemic stroke is a sudden loss of circulation to a portion of the brain that results in a loss of neurologic function. Many ischemic strokes are embolic. They result from a thrombus traveling into the central circulation and occluding a blood vessel. Treatment of ischemic stroke with recombinant tissue plasminogen activator (tPA) can improve patient outcomes. However, tPA must be used during a specific time window after the stroke onset to be effective and it risks converting an ischemic stroke into a hemorrhagic one. We explore the basic effects of fibrin‐modifying proteases on neurons, astrocytes, and microglia during ischemia. tPA, thrombin, and plasmin can initiate microglial activation and change both neuronal and astrocytic survival. As a result of these functions and of their role in blood homeostasis, all three of these proteases have profound effects on neurons and glial cells in the brain and are capable of altering the development and severity of ischemic stroke. © 2005 Wiley‐Liss, Inc.
Astrocytic contributions to bioenergetics of cerebral ischemia
Authors: Dienel Gerald A. , Hertz Leif
Published: April 2005

Astrocytes are multifunctional cells that interact with neurons and other astrocytes in signaling and metabolic functions, and their resistance to pathophysiological conditions can help restrict loss of tissue after an ischemic event provided adequate nutrients are supplied to support their requirements. Astrocytes have substantial oxidative capacity and mechanisms to upregulate glycolytic capability when respiration is impaired. An astrocytic enzyme that synthesizes a powerful activator of glycolysis is not present in neurons, endowing astrocytes with the ability to sustain ATP production under restrictive conditions. The monocarboxylic acid transporter (MCT) isoforms predominating in astrocytes are optimized to facilitate very large increases in lactate flux as lactate concentration increases within (1–3 mM) and above (>3 mM) the normal range. In sharp contrast, the major neuronal MCT serves as a barrier to increased transmembrane transport as lactate rises above 1 mM, restricting both entry and efflux. Lactate can serve as fuel during recovery from ischemia but direct evidence that lactate is oxidized by neurons (vs. astrocytes) to maintain synaptic function is lacking. Astrocytes have critical roles in regulation of ionic homeostasis and control of extracellular glutamate levels, and spreading depression associated with ischemia places high demands on energy supplies in astrocytes and contributes to metabolic exhaustion and demise. Disruption of Ca2+homeostasis, generation of oxygen free radicals and nitric oxide, and mitochondrial depolarization contribute to astrocyte death during and after a metabolic insult. Novel pharmaceutical agents targeted to astrocytes and hyperoxic therapy that restores penumbral oxygen level during energy failure might improve postischemic outcome. © 2005 Wiley‐Liss, Inc.
Ischemia‐induced programmed cell death in astrocytes
Authors: Giffard Rona G. , Swanson Raymond A.
Published: April 2005

Astrocytes are essential for neuronal survival and function, neurogenesis, and neural repair. Although astrocytes are more resistant than neurons to most stress conditions in vitro, certain astrocyte subtypes, such as the glial fibrillary acidic protein (GFAP)‐negative protoplasmic astrocytes that predominate in gray matter structures, may be equally or more sensitive than neurons to ischemia in vivo. Programmed cell death differs from passive, necrotic death in that cell constituents actively participate in cell demise. Like neurons, astrocytes undergo programmed cell death during normal development. Cell culture studies have shown that astrocytes can be induced to undergo apoptosis and other forms of programmed cell death by many factors relevant to ischemia, including acidosis, oxidative stress, substrate deprivation, and cytokines. Animal models of cerebral ischemia have confirmed nuclear condensation and upregulation of Bax and caspases in a subset of astrocytes exposed to ischemia, especially in immature brain. A causal role for these events in astrocyte death is supported by improved astrocyte survival after inhibition of caspase‐dependent cell death pathways. Astrocyte survival is also improved by blocking the poly(ADP‐ribose)‐1 cell death pathway. Markers of programmed cell death are generally less evident and less widespread in astrocytes than in neighboring neurons. However, most studies to date have relied only on markers of classical apoptosis. In addition, these studies have relied almost exclusively on GFAP to identify astrocytes. Since most protoplasmic astrocytes are poorly immunoreactive for GFAP, the extent of ischemia‐induced programmed cell death in this cell type remains uncertain. © 2005 Wiley‐Liss, Inc.
Astrocytic swelling in cerebral ischemia as a possible cause of injury and target for therapy
Authors: Kimelberg Harold K.
Published: April 2005

In this viewpoint article, I summarize data showing that the astrocytic swelling that occurs early after the acute CNS pathologies ischemia and traumatic brain injury is damaging. We have proposed that one reason may be the release of excitatory amino acids (EAA) via volume‐activated anion channels (VRACs) that are activated by such swelling. This release could be a target for therapy, which could involve blocking the astrocytic swelling or the release mechanisms. The transport mechanisms likely causing the early astrocytic swelling are therefore summarized. In terms of targeting the release mechanisms, we have found a potent inhibitor of VRACs, tamoxifen, to be strongly neuroprotective in focal ischemia with a therapeutic window of 3 h after initiation of the ischemia. The question, however, of whether neuroprotection by tamoxifen can be solely attributed to VRAC inhibition in astrocytes has yet to be resolved. ©2005 Wiley‐Liss, Inc.
CD163‐positive perivascular macrophages in the human CNS express molecules for antigen recognition and presentation
Authors: Fabriek Babs O. , Van Haastert Elise S. , Galea Ian , Polfliet Machteld M.J. , Döpp Ed D. , Van Den Heuvel Michel M. , Van Den Berg Timo K. , De Groot Corline J.A. , Van Der Valk Paul , Dijkstra Christine D.
Published: April 2005

Perivascular macrophages (PVM) constitute a subpopulation of resident macrophages in the central nervous system (CNS) that by virtue of their strategic location at the blood‐brain barrier potentially lend themselves to a variety of important functions in both health and disease. Functional evidence suggests that PVM play a supportive role during experimental autoimmune encephalomyelitis in rodents. However, the function of PVM in the human CNS remains poorly characterized. We first set out to investigate the validity of the antibody EDhu1, which recognizes human CD163, to specifically identify human PVM. Second, we wanted to gain insight into the function of PVM in antigen recognition and presentation and therefore we studied the expression of DC‐SIGN, mannose receptor, MHC class II, and several costimulatory molecules by PVM in the normal and inflamed human CNS (multiple sclerosis (MS) brain lesions). Conventional immunohistochemistry and double‐labeled immunofluorescence techniques were used. We show that CD163 specifically reveals PVM in the normal human CNS. In MS lesions, CD163 staining reveals expression on foamy macrophages and microglia, besides an upregulation of the amount of PVM stained. In contrast, mannose receptor expression is restricted to PVM in both normal and inflamed brain tissue. Furthermore, we show that a subpopulation of PVM in the human brain express several molecules involved in antigen recognition, presentation, and costimulation. Therefore PVM, which occupy a strategic location at the BBB, are equipped to recognize antigen and present it to T cells, supporting a role in the regulation of perivascular inflammation in the human CNS. © 2005 Wiley‐Liss, Inc.
Meta‐analysis of functional imaging data using replicator dynamics
Authors: Neumann Jane , Lohmann Gabriele , Derrfuss Jan , von Cramon D. Yves
Published: April 2005

Despite the rapidly growing number of meta‐analyses in functional neuroimaging, the field lacks formal mathematical tools for the quantitative and qualitative evaluation of meta‐analytic data. We propose to use replicator dynamics in the meta‐analysis of functional imaging data to address an important aspect of neuroimaging research, the search for functional networks of cortical areas that underlie a specific cognitive task. The replicator process requires as input only a list of activation locations, and it results in a network of locations that jointly show significant activation in most studies included in the meta‐analysis. These locations are likely to play a critical role in solving the investigated cognitive task. Our method was applied to a meta‐analysis of the Stroop interference task using data provided by the publicly accessible database BrainMap DBJ. Hum Brain Mapp 25:165–173, 2005. © 2005 Wiley‐Liss, Inc.
Beyond hypofrontality: A quantitative meta‐analysis of functional neuroimaging studies of working memory in schizophrenia
Authors: Glahn David C. , Ragland J. Daniel , Abramoff Adir , Barrett Jennifer , Laird Angela R. , Bearden Carrie E. , Velligan Dawn I.
Published: April 2005

Although there is considerable evidence that patients with schizophrenia fail to activate the dorsolateral prefrontal cortex (DLPFC) to the degree seen in normal comparison subjects when performing working memory or executive tasks, hypofrontality may be coupled with relatively increased activity in other brain regions. However, most imaging studies of working memory in schizophrenia have focused on DLPFC activity. The goal of this work is to review functional neuroimaging studies that contrasted patients with schizophrenia and healthy comparison subjects during a prototypical working memory task, the n‐back paradigm, to highlight areas of hyper‐ and hypoactivation in schizophrenia. We utilize a quantitative meta‐analysis method to review 12 imaging studies where patients with schizophrenia were contrasted with healthy comparison subjects while performing the n‐back paradigm. Although we find clear support for hypofrontality, we also document consistently increased activation in anterior cingulate and left frontal pole regions in patients with schizophrenia compared to that in controls. These data suggest that whereas reduced DLPFC activation is reported consistently in patients with schizophrenia relative to healthy subjects, abnormal activation patterns are not restricted to this region, raising questions as to whether the pathophysiological dysfunction in schizophrenia is specific to the DLPFC and about the relationship between impaired performance and aberrant activation patterns. The complex pattern of hyper‐ and hypoactivation consistently found across studies implies that rather than focusing on DLPFC dysregulation, researchers should consider the entire network of regions involved in a given task when making inferences about the biological mechanisms of schizophrenia. Hum Brain Mapp 25:60–69, 2005. © 2005 Wiley‐Liss, Inc.
A review of pervaporation for product recovery from biomass fermentation processes
Authors: Vane Leland M
Published: April 2005

Although several separation technologies are technically capable of removing volatile products from fermentation broths, distillation remains the dominant technology. This is especially true for the recovery of biofuels such as ethanol. In this paper, the status of an emerging membrane‐based technology, called pervaporation, for this application is reviewed. Several issues and research priorities which will impact the ability of pervaporation to be competitive for biofuel recovery from fermentation systems are identified and discussed. They include: increased energy efficiency; reduction of capital cost for pervaporation systems; longer term trials with actual fermentation broths; optimized integration of pervaporation with fermentor; synergy of performing both alcohol recovery and solvent dehydration by pervaporation with dephlegmation fractional condensation technology; and updated economic analyses of pervaporation at various biofuel production scales. Pervaporation is currently viable for biofuel recovery in a number of situations, but more widespread application will be possible when progress has been made on these issues. Published in 2005 for SCI by John Wiley & Sons, Ltd.
Involvement of Ca2+/calmodulin‐dependent protein kinase II in the modulation of indolamines in diabetic and hyperglycemic rats
Authors: Ramakrishnan R. , Prabhakaran K. , Jayakumar A.R. , Gunasekaran P. , Sheeladevi R. , Suthanthirarajan N.
Published: April 2005

Hyperglycemia and acidosis are the key factors in diabetic complications. It has been shown that acute or chronic diabetes alters serotonin levels in brain. However, the mechanism of hyperglycemia‐ or acidosis‐induced changes in serotonin levels remains poorly understood. Because Ca2+‐dependent protein kinases play a major role in the regulation of serotonin synthesis and release, we investigated the effect of diabetes, hyperglycemia, and acidosis on the level of indolamines [5‐hydroxytryptamine (5‐HT) and/or 5‐hydroxyindoleacetic acid (5‐HIAA)] and Ca(2+)/calmodulin‐dependent protein kinase II (CaMKII) enzyme activity or protein expression in different brain regions. Alloxan‐induced (45 mg/kg bw) diabetic rats (30 days) showed increased level of 5‐HT in striatum (ST; 183%), midbrain (MB; 199%), pons medulla (PM; 151%), cerebellum (CB; 214%), and cerebral cortex (CCX; 162%) compared with control (P < 0.05), and these changes were reversed after insulin administration. Rats treated with glucose (500 mg/kg bw) for 30 days showed a 146%, 183%, 208%, and 177% (P < 0.05) increase in 5‐HT levels in ST, PM, CB, and CCX, respectively. 5‐HIAA level increased in hippocampus (HC; 172%) and in MB (145%; P < 0.05). In addition, rats treated with sodium acetoacetate (NaAcAc) for 30 days (60 mg/kg bw) showed significant increases (P < 0.05) of 5‐HT level in ST (152%) and MB (174%). However, the levels of 5‐HIAA increased only in MB (151%, P < 0.05). Rats treated with NH4Cl, which induced acidosis (150 mg/kg bw), showed an increased level of 5‐HT only in HC (165%, P < 0.05). The increased activity and protein expression of CaMKII in ST, MB, PM, CB, and CCX under diabetic conditions were correlated with the levels of indolamines changes during diabetic, hyperglycemic, or acidotic conditions. These results suggest that CaMKII may be involved in the regulation of indolamines in diabetic animals. © 2005 Wiley‐Liss, Inc.
Cover Picture: Macromol. Chem. Phys. 8/2005
Authors: Amado Elkin , Kressler Jörg
Published: April 2005

Cover: α,ω‐Perfluoroalkyl‐functionalized poly(ethylene oxide) water‐soluble polymers self‐assemble spontaneously in water through their hydrophobic end groups into micelles and other supramolecular aggregates, as demonstrated by dynamic light scattering. The cleavage of the ester bond occurs rapidly in water due to the higher electrophilicity of the perfluorinated moieties in contrast to the non‐fluorinated analogues. Further details can be found in the Full Paper by E. Amado and J. Kressler* on page 850.
Low‐Density Polyethylene (LDPE) Surface With a Wettability Gradient by Tuning its Microstructures
Authors: Lu Xiaoying , Zhang Jilin , Zhang Changchun , Han Yanchun
Published: April 2005

Summary: We describe an interesting approach to the fabrication of wettability gradients from hydrophobicity to superhydrophobicity in low‐density polyethylene (LDPE) films by first forming high porosity surfaces and placing the specimens onto linear temperature gradients. While the polymer chosen for the study is non‐polar, its microporous layer provides sufficient superhydrophobicity. Lateral gradient heating of the layer results in partial melting of the polymer and correspondingly decreases porosity thus decreasing hydrophobicity.

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Hairy PEO‐Silica Nanoparticles through Surface‐Initiated Polymerization of Ethylene Oxide
Authors: Joubert Mathieu , Delaite Christelle , Bourgeat‐Lami Elodie , Dumas Philippe
Published: April 2005

Summary: The grafting of poly(ethylene oxide) (PEO) onto silica nanoparticles was performed in situ by the ring‐opening polymerization of the oxirane monomer initiated from the mineral surface using aluminium isopropoxide as an initiator/heterogeneous catalyst. Alcohol groups were first introduced onto silica by reacting the surfacic silanols with prehydrolyzed 3‐glycidoxypropyl trimethoxysilane. The alcohol‐grafted silica played the role of a coinitiator/chain‐transfer agent in the polymerization reaction and enabled the formation of irreversibly bonded polymer chains. Silica nanoparticles containing up to 40 wt.‐% of a hairy layer of grafted PEO chains were successfully produced by this technique.

The grafting of poly(ethylene oxide) (PEO) onto silica nanoparticles by in‐situ ring‐opening polymerization of the oxirane monomer.

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The grafting of poly(ethylene oxide) (PEO) onto silica nanoparticles by in‐situ ring‐opening polymerization of the oxirane monomer.
Polypeptide‐Shelled Poly(propylene imine) Dendrimers and Their Complexing Properties towards Copper(II) Ions
Authors: Appelhans Dietmar , Komber Hartmut , Kirchner Ralf , Seidel Jürgen , Huang Chih‐Feng , Voigt Dieter , Kuckling Dirk , Chang Feng‐Chih , Voit Brigitte
Published: April 2005

Summary: Polypeptide‐shelled poly(propylene imine) dendrimers were realized by ring‐opening polymerization of α‐amino acid N‐carboxyanhydrides, initiated by dendrimers as core molecules. Polypeptides with 2nd generation core were used as model compounds to investigate interior complexes between metal ion and surface‐modified dendrimers. Micro‐calorimetric measurements outlined the formation of approximate 1:1 complexes between CuII and polypeptide‐shelled dendrimers and the influence of polypeptide chain compositions on differential molar heats of complexation.

Composition of one of the polypeptides synthesized.

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Composition of one of the polypeptides synthesized.
Determination of the Vapor Density of Triacetone Triperoxide (TATP) Using a Gas Chromatography Headspace Technique
Authors: Oxley Jimmie C. , Smith James L. , Shinde Kajal , Moran Jesse
Published: April 2005

Using a GC headspace measurement technique, the vapor pressure of TATP was determined over the temperature range 12 to 60 °C. As a check on the experimental method, TNT vapor pressure was likewise computed. Values for TNT are in excellent agreement with previous published ones. For TATP the vapor pressure was found to be ~ 7 Pa at ambient conditions. This value translates to a factor of 104 more molecules of TATP in air than TNT at room temperature. The dependence of TATP vapor pressure on temperature can be described by the equation log10P(Pa)=19.791−5708/T(K). Its heat of sublimation has been calculated as 109 kJ/mol.
Comprehensive evaluation of chip interleaving effect on turbo‐coded DS‐SS in a Rayleigh fading channel with antenna diversity reception
Authors: Garg Deepshikha , Adachi Fumiyuki
Published: April 2005

In this paper, we present a comprehensive performance evaluation of chip interleaving effect on turbo coded direct sequence spread spectrum (DS‐SS) system in a frequency non‐selective Rayleigh fading channel with antenna diversity reception. At the transmitter, chip interleaver scrambles the SF (spreading factor) chips associated with a data symbol and transforms the transmission channel into a highly time‐selective or highly memoryless channel at the chip level. The use of chip interleaving is equivalent to using SF‐antenna diversity reception with correlated fading among the branches and with reduced average received signal power per antenna by a factor of SF. We theoretically analyze how chip interleaving alters the received signal statistics. Then, the effect of the various parameters, viz. interleaver size, interleaving depth, information sequence length, spreading factor and the fading maximum Doppler frequency, are also evaluated. It is found that the bit error rate (BER) performance improves with increasing spreading factor and increasing frame length. Chip interleaving is found to be effective in the presence of receive antenna diversity as well. Copyright © 2005 John Wiley & Sons, Ltd.
Reoperation for hyperparathyroidism
Authors: Edis Anthony J. , Beahrs Oliver H. , Sheedy Patrick F.
Published: April 2005

Reoperation for persistent or recurrent hyperparathyroidism is more hazardous than is primary cervical exploration and is also much less likely to result in cure of the disease. Only 21 of 34 reoperations (62%) were successful during the period 1970 through 1972 at the Mayo Clinic, compared with success in 312 of 327 primary operations (95%). In 9 patients who had their initial exploration at this institution, the most common cause of failure at the first operation was inadequate treatment of multiglandular disease; in 25 patients who were first operated on elsewhere, missed adenomas were far more common.

Parathyroid arteriography and selective venous sampling with parathyroid hormone assays should improve the results of reoperation by providing preoperative localization of hyperfunctioning parathyroid glands in difficult cases. These procedures, however, are expensive and technically difficult, and they are not always successful. They are also associated with a definite morbidity, which must be weighed against any anticipated benefits. The systematic evaluation and treatment of patients facing reoperation for hyperparathyroidism should be undertaken in special centers accustomed to dealing with these difficult problems.
Bile duct and liver pathology in biliary atresia
Authors: Haas Joel E.
Published: April 2005

Progression to cirrhosis despite restoration of bile flow by successful portoenterostomy suggests that factors other than obstruction alone are operative in biliary atresia. This paper describes pathologic changes at all levels of the hepatobiliary secretory apparatus from hepatocyte to common duct, exhibited in liver biopsies, resected portions of liver adjacent to the porta hepatis, and extrahepatic duct remnants from 17 patients operated upon for relief of biliary atresia. In both intra‐ and extrahepatic bile ducts, there were epithelial changes interpreted as occurring in a sequence of vacuolar degeneration, necrosis, inflammatory infiltration, and proliferative epithelial repair that precede obliterative fibrosis. From their distribution, it is inferred that these cytopathologic changes may not be simply due to distal obstruction. These ductal epithelial changes are similar to those that occur in livers of some patients with severe viral hepatitis. The association of these changes with giant cell transformation in all cases suggests that they reflect a common etiology for ductal and hepatocellular damage in the neonatal hepatitis‐biliary atresia spectrum. The persistence of these changes in liver biopsies following portoenterostomy suggests that they may be of pathogenetic significance in the progressive liver disease seen in most patients with biliary atresia.
Surgical treatment of pneumopericardium in the neonate
Authors: Emery Robert W. , Landes Ronald G. , Lindsay William G. , Thompson Theodore , Nicoloff Demetre M.
Published: April 2005

Pneumopericardium occurred in 28 neonates with respiratory distress syndrome at the University of Minnesota Hospitals and St. Paul Children's Hospital from July 1, 1972 through June 30, 1976. All patients developed this complication while on mechanical ventilatory support with positive end‐expiratory pressure (2–12 cm water). In 23 patients, pneumopericardium resulted in clinical pericardial tamponade that necessitated cardiac resuscitation. The clinical presentation of pericardial tamponade consisted of muffled, distant heart sounds, hypotension, bradycardia, and hypoxia with cyanosis. The diagnosis was confirmed by chest x‐ray. Pneumothorax, pneumomediastinum, and/or pneumoperitoneum were associated with the appearance of pneumopericardium in 93% of the cases. Treatment consisted of: (a) needle pericardial aspiration in 7 patients, of which 5 survived; (b) pericardial tube placement with application of suction in 10 patients, of which 8 survived; (c) no treatment in 16 patients, of which 5 survived. Overall, 13 patients (46%) survived pneumopericardium and 15 patients (54%) died. Complications of treatment developed in 5 patients; 3 developed pneumothorax and 2 developed myocardial lacerations from percutaneous placement of a plastic drainage catheter. Of 5 asymptomatic patients, 2 (40%) died as a result of pneumopericardium. Based on our experience, it is recommended that pneumopericardium be evacuated whenever it is diagnosed. Initially, needle aspiration of the pericardial sac should be performed to manage the acute episode and stabilize the patient, and then a chest catheter of No. 10 Fr. caliber should be placed under direct vision into the pericardial sac and maintained on suction until positive end‐expiratory pressure ventilation has been discontinued.
Regulation of gastrointestinal mucosal growth
Authors: Johnson Leonard R.
Published: April 2005

This article reviews the possible mechanisms initiated by the ingestion and presence of food in the digestive tract that might regulate the growth of gastrointestinal mucosa. Emphasis is placed on direct local nutrition, pancreatic and biliary secretions, and gastrointestinal hormones. The strong and weak points of each of these are discussed in regard to its ability to account for experimental data. Areas of controversy are emphasized and, in some cases, attempts at reconciliation are made. Many of the data in this field of research are descriptive; future studies should focus on the actual mechanisms of regulation.